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Purpose: Hyperuricemia (HUA) and hypertriglyceridemia (HTG) were very common in chronic kidney disease (CKD) and associated with accelerated progression of CKD. This was a retrospective, cross-sectional study which aimed to explore the relationship between serum uric acid levels or triglyceride levels and tubular atrophy/interstitial fibrosis (proven by renal biopsy)., Methods: The present study enrolled 229 CKD individuals who included 127 biopsy-proven primary IgA nephrology (IgAN) patients and 102 biopsy-proven primary membranous nephropathy (MN) patients. The baseline characteristics at the time of the kidney biopsy were collected. According to the serum uric acid (UA) or triglyceride (TG) whether it exceeds the normal reference range, patients were divided into non-HUA (n = 127), HUA (n = 102), non-HTG (n = 119), and HTG group (n = 110). Based on the extent of tubular atrophy/interstitial fibrosis, patients were divided into no/mild injury (T0, n = 127), moderate injury (T1, n = 102). Multivariable logistic regression for factors predicting moderate tubular atrophy/interstitial fibrosis was performed., Results: There were 127 IgAN and 102 MN cases among 229 patients in the present study. The prevalence of HUA was 44.5% (n = 102), 40.9% (n = 52), and 49.0% (n = 50) in all patients, IgAN patients and MN patients, respectively (P = 1.49). The prevalence of HTG was 48.0% (n = 110), 29.9% (n = 38), and 70.6% (n = 72) (P < 0.001), respectively, as well. Multivariate logistic regression analysis showed that HUA and HTG were independent risk factors for moderate tubular atrophy/interstitial fibrosis (HUA OR = 2.335, 95% CI = 1.147-4.755, P = 0.019; HTG OR = 2.646, 95% CI = 1.289-5.432, P = 0.008). The area under curve (AUC) of model 1 (HUA + eGFR + HTG + age + serum globulin + 24 h urinary protein, AUC = 0.876) was larger than the other two models; however, there was no significant difference among these models (all P > 0.05)., Conclusions: Hyperuricemia and hypertriglyceridemia, which were prevalent in CKD patients, were the independent risk factors for moderate tubular atrophy/interstitial fibrosis. HUA together with HTG could improve the value of diagnosis for moderate tubular atrophy/interstitial fibrosis to some extent., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

Purpose: Diabetic nephropathy (DN) is one of the most serious complications of diabetes that leads to decline of renal function. Although numerous studies have revealed that microRNAs (miRNAs) play essential roles in the progression of DN, whether miR-365 is involved remains elusive., Methods: The successful construction of DN model was confirmed by ELSIA, hematoxylin-eosin (HE) and Masson staining assay. The expression of miR-365 was detected through RT-qPCR. The levels of BDNF, p-TrkB, α-smooth muscle actin (SMA), collagen IV (Col.IV), transforming growth factor-β1 (TGF-β1), tumor necrosis factor α (TNF-α), and interleukin-6 (IL-6) were evaluated by western blot, IF or ELISA assays. Luciferase reporter assay was used to detect the interaction between miR-365 and BDNF., Results: The DN mice model was induced by streptozotocin (STZ). Then miR-365 expression was found to upregulate in tissues of DN rat. Furthermore, elevated expression of miR-365 was found in high glucose (HG)-treated HK-2 cells. Silencing of miR-365 suppressed the accumulation of ECM components and secretion of inflammatory cytokines in HK-2 cells. In addition, it was demonstrated that miR-365 could target BDNF. The protein levels of BDNF and p-TrkB were negatively regulated by miR-365 in HK-2 cells. Moreover, inhibition of miR-365 suppressed the levels of SMA, Col.IV, TGF-β1, TNF-α, and IL-6, indicating the renal fibrosis was inhibited by miR-365 knockdown., Conclusion: MiR-365 could regulate BDNF-TrkB signal axis in STZ induced DN fibrosis and renal function. The results of the current study might provide a promising biomarker for the treatment of DN in the future., (© 2021. The Author(s), under exclusive licence to Springer Nature B.V.)

Patients with chronic kidney disease (CKD) have a high cardiovascular mortality. CKD and heart failure (HF) coexist in up to 50% of patients, and both associate with inflammation. We aimed to define the cardiac phenotype of a novel swine model of CKD and test the hypothesis that inflammation of renal origin propels the development of precursors of HF in CKD. CKD was induced in 14 pigs, which were followed for 14 wk. Renal (multidetector computed tomography) and cardiac (echocardiography) hemodynamics were quantified before and 8 wk after single intrarenal administration of placebo or a biopolymer-fused peptide inhibitor of NF-κB that blocks NF-κB activity and decreases inflammatory activity (SynB1-ELP-p50i). Blood was collected to quantify cytokines (TNF-α, monocyte chemoattractant protein-1, and interleukins), markers of inflammation (C-reactive protein), and biomarkers of HF (atrial and brain natriuretic peptides). Pigs were then euthanized, and kidneys and hearts were studied ex vivo. Normal pigs were used as time-matched controls. Renal dysfunction in CKD was accompanied by cardiac hypertrophy and fibrosis, diastolic dysfunction, increased renal and cardiac expression of TNF-α, monocyte chemoattractant protein-1, and interleukins, canonical and noncanonical mediators of NF-κB signaling, circulating inflammatory factors, and biomarkers of HF. Notably, most of these changes were improved after intrarenal SynB1-SynB1-ELP-p50i, although cardiac inflammatory signaling remained unaltered. The translational traits of this model support its use as a platform to test novel technologies to protect the kidney and heart in CKD. A targeted inhibition of renal NF-κB signaling improves renal and cardiac function, suggesting an inflammatory renal-cardio axis underlying early HF pathophysiology in CKD. NEW & NOTEWORTHY Chronic kidney disease (CKD) is a progressive disorder with high cardiovascular morbidity and mortality. This work supports the role of inflammatory cytokines of renal origin in renal-cardio pathophysiology in CKD and that the heart may be a target. Furthermore, it supports the feasibility of a new strategy in a translational fashion, using targeted inhibition of renal NF-κB signaling to offset the development of cardiac injury in CKD.

Renal fibrosis is common especially in the elderly population. Recently, we found that vitamin D deficiency caused prostatic hyperplasia. This study aimed to investigate whether vitamin D deficiency promotes renal fibrosis and functional impairment. All mice except controls were fed with vitamin D-deficient (VDD) diets, beginning from their early life. The absolute and relative kidney weights on postnatal week 20 were decreased in VDD diet-fed male pups but not in female pups. A mild pathological damage was observed in VDD diet-fed male pups but not in females. Further analysis showed that VDD-induced pathological damage was aggravated, accompanied by renal dysfunction in 40-week-old male pups. An obvious collagen deposition was observed in VDD diet-fed 40-week-old male pups. Moreover, renal α-smooth muscle actin (α-SMA), a marker of epithelial-mesenchymal transition (EMT), and Tgf-β mRNA were up-regulated. The in vitro experiment showed that 1,25-dihydroxyvitamin D3 alleviated transforming growth factor-β1 (TGF-β1)-mediated down-regulation of E-cadherin and inhibited TGF-β1-evoked up-regulation of N-cadherin, vimentin and α-SMA in renal epithelial HK-2 cells. Moreover, 1,25-dihydroxyvitamin D3 suppressed TGF-β1-evoked Smad2/3 phosphorylation in HK-2 cells. These results provide experimental evidence that long-term vitamin D deficiency promotes renal fibrosis and functional impairment, at least partially, through aggravating TGF-β/Smad2/3-mediated EMT in middle-aged male mice.

Introduction: Increasing evidence has demonstrated that loss of peritubular capillaries plays a critical role in renal interstitial fibrosis. Leucine-rich α2-glycoprotein-1 (LRG1) has been observed promoting angiogenesis in the ocular disease mouse model and myocardial infarction model. We aimed to explore the role of LRG1 in renal interstitial fibrosis., Methods: We analyzed the expression of LRG1 in the plasma and kidney of CKD patients by ELISA and immunohistochemistry. Relationships between the expression of LRG1 in plasma and kidney and renal fibrosis and inflammation were analyzed. Tube formation assay was used to detect the angiogenesis in the human umbilical vein endothelial cell lines (HUVECs). And real-time PCR was used to detect the mRNA expression of LRG1, inflammatory factors, renal tubular injury indicators, pro-fibrotic cytokines, and CD31. We examined the effects of genetic ablation of LRG1 on renal fibrosis induced by unilateral ureteral obstruction (UUO) mice model at day 7., Results: We demonstrated that the expression of LRG1 in renal tissues and plasma samples was upregulated in CKD patients. And the expression of LRG1 was elevated in human renal tubular epithelial cell line (HK-2) cells in response to the stimulation of TNF-α in vitro, and in kidney after UUO in vivo. The deficiency of the LRG1 gene aggravated renal fibrosis, inflammatory cells infiltration, and capillary rarefaction after UUO. In vitro, LRG1 promoted the tube formation of HUVEC cells. LRG1 inhibits fibronectin secretion induced by TGF-β1 in HK-2 and overexpression of LRG1 in HK-2 cells decreased fibronectin secretion., Conclusion: LRG1 may prevent renal fibrosis by inhibiting the secretion of inflammatory and pro-fibrotic cytokines and promoting angiogenesis., (© 2021 S. Karger AG, Basel.)

Tissue kallikrein has protective function against various types of injury. In this study, we investigated whether exogenous pancreatic kininogenase (PK) conferred renoprotection in a rat model of unilateral ureteral obstruction (UUO) and H 2 O 2 -treated HK-2 cells in vitro. SD rats were subjected to UUO surgery, then PK (7.2 U/g per day, ip) was administered for 7 or 14 days. After the treatment, rats were euthanized; the obstructed kidneys were harvested for further examination. We found that PK administration significantly attenuated interstitial inflammation and fibrosis, and downregulated the expression of proinflammatory (MCP-1, TLR-2, and OPN) and profibrotic (TGF-β1 and CTGF) cytokines in obstructed kidney. UUO-induced oxidative stress, closely associated with excessive apoptotic cell death and autophagy via PI3K/AKT/FoxO1a signaling, which were abolished by PK administration. We further showed that PK administration increased the expression of bradykinin receptors 1 and 2 (B1R and B2R) mRNA and the production of NO and cAMP in kidney tissues. Coadministration with either B1R antagonist (des-Arg9-[Leu8]-bradykinin) or B2R antagonist (icatibant) abrogated the renoprotective effects of PK, and reduced the levels of NO and cAMP in obstructed kidney. In H 2 O 2 -treated HK-2 cells, addition of PK (6 pg/mL) significantly decreased ROS production, regulated the expression of oxidant and antioxidant enzymes, suppressed the expression of TGF-β1 and MCP-1, and inhibited cell apoptosis. Our data demonstrate that PK treatment protects against the progression of renal fibrosis in obstructed kidneys.

We previously found that polydatin could attenuate renal oxidative stress in diabetic mice and improve renal fibrosis. Recent evidence shows that NADPH oxidase 4 (Nox4)-derived reactive oxygen species (ROS) contribute to inflammatory and fibrotic processes in diabetic kidneys. In this study we investigated whether polydatin attenuated renal fibrosis by regulating Nox4 in vitro and in vivo. In high glucose-treated rat glomerular mesangial cells, polydatin significantly decreased the protein levels of Nox4 by promoting its K48-linked polyubiquitination, thus inhibited the production of ROS, and eventually decreasing the expression of fibronectin (FN) and intercellular adhesion molecule-1 (ICAM-1), the main factors that exacerbate diabetic renal fibrosis. Overexpression of Nox4 abolished the inhibitory effects of polydatin on FN and ICAM-1 expression. In addition, the expression of Connexin32 (Cx32) was significantly decreased, which was restored by polydatin treatment. Cx32 interacted with Nox4 and reduced its protein levels. Knockdown of Cx32 abolished the inhibitory effects of polydatin on the expression of FN and ICAM-1. In the kidneys of streptozocin-induced diabetic mice, administration of polydatin (100 mg·kg -1 ·d -1 , ig, 6 days a week for 12 weeks) increased Cx32 expression and reduced Nox4 expression, decreased renal oxidative stress levels and the expression of fibrotic factors, eventually attenuating renal injury and fibrosis. In conclusion, polydatin promotes K48-linked polyubiquitination and degradation of Nox4 by restoring Cx32 expression, thereby decreasing renal oxidative stress levels and ultimately ameliorating the pathological progress of diabetic renal fibrosis. Thus, polydatin reduces renal oxidative stress levels and attenuates diabetic renal fibrosis through regulating the Cx32-Nox4 signaling pathway.

Survival time of kidney transplant patients is primarily threatened by chronic allograft dysfunction (CAD), whose typical feature is interstitial fibrosis and tubular atrophy (IF/TA). CAD could be caused by ischemia-reperfusion injury (IRI) during renal transplantation. MiR-378 is correlated with multiple kidney diseases and implicated in CAD. To clarify the underlying mechanism of miR-378 on renal allograft, we utilize renal unilateral IRI mice and H/R NRK52E cells. To evaluate the acute tubular damage, we determined the apoptotic rate by TUNEL assay and examined mice kidney sections of H&E staining 1 day after IRI. To assess the chronic renal interstitial inflammation and fibrosis, we detected the infiltration rates of CD45R + leukocytes and Ly6b + neutrophils by immunohistochemistry, examined mice kidney sections of picrosirius staining and measured the mRNA level of Col1a1 14 days after IRI. To investigate the H/R injury of NRK52E cells, MTT assay was performed to detect cell viability, TUNEL assay was performed to determine apoptotic rate and luciferase reporter assay was carried out to demonstrate the potential target of miR-378. Moreover, we determined the levels of miR-378 of renal allograft biopsies in healthy patients and patients diagnosed with IF/TA. We found agomir-378 treatment significantly reduced the apoptotic rate and tubular damage scores assessed by H&E staining 1 day after IRI. Agomir-378 treatment also decreased infiltration rates of both CD45R + leukocytes and Ly6b + neutrophils and fibrosis examined by picrosirius staining and by the mRNA level of Col1a1 14 days after IRI. Experiments in vitro revealed that miR-378 increased cell viability and decreased apoptotic rate of NRK52E cells subjected to H/R. Additionally, luciferase reporter assay confirmed that caspase 3 was targeted by miR-378 directly. Furthermore, we found the levels of miR-378 were significantly lower in renal allografts of patients with IF/TA than those of healthy controls. Taken together, we have found that miR-378 has potential protective effects on renal allografts to prevent IRI during kidney transplantation and following IF/TA of renal allografts.

Purpose: Chronic kidney disease (CKD) has become a global public health problem and accompanied by renal fibrosis. MiR-194, a tumor suppressor gene, has been previously reported to be associated with the pathogenesis of tissue fibrosis. However, the role of miR-194 in the pathogenesis of renal fibrosis remains unknown., Methods: A renal fibrosis model was constructed by unilateral ureteral obstruction (UUO) in male C57BL/6 mice. HE and MASSON stainings were used for histological analysis. The expression level of miR-194 was detected by RT-qPCR. The protein expression was detected by western blotting. The levels of inflammatory cytokines were detected by ELISA. The relationship between miR-194 and Runx1 was further verified by dual luciferase reporter assay., Results: The results showed that miR-194 level was downregulated in kidney tissue of UUO mice, accompanied by significantly pathological damage and renal fibrosis. MiR-194 mimics significantly reduced pathological damage and alleviated renal fibrosis that caused by UOO, and inhibited the expression levels of α-SMA and collagen I. In addition, miR-194 mimics also reduced the expression level of serum inflammatory factors. Moreover, in vitro analysis indicated that Runx1 was a downstream target gene of miR-194. Furthermore, mechanism analysis indicated that miR-194 reduced mouse renal fibrosis by inhibiting the Runx1/AKT pathway in vivo and in vitro., Conclusion: The present findings suggested that miR-194 targets Runx1/Akt pathway to reduce renal fibrosis in UOO-induced mice. This study provides a novel strategy for the prevention and treatment of renal fibrosis.

Renal fibrosis is the most common pathological manifestation of chronic kidney disease (CKD), and with numerous influencing factors, its pathogenesis is complex. Epithelial-mesenchymal transition (EMT) is known to promote the progression of renal fibrosis via alterations in the secreted proteome. Moreover, blocking or even reversing EMT can effectively reduce the degree of fibrosis. As such, targeting the key molecules responsible for promoting EMT may be an effective strategy for inhibiting renal fibrosis. Research in recent years has demonstrated that hypoxia-inducible factor 1α (HIF-1α) acts to promote renal fibrosis through regulation of EMT. However, the relationship between HIF-1α and EMT remains incompletely understood. In the present review, the underlying mechanism of the interaction between HIF-1α and EMT is explored to provide novel insight into the pathogenesis of renal fibrosis and new ideas for early targeted intervention.

Maternal endotoxemia has been shown to increase renal collagen deposition in the offspring. Renal fibrosis is a hallmark of progressive chronic kidney disease. It was investigated whether maternal reactive oxygen species (ROS) leads to renal fibrosis or exacerbates unilateral ureteral obstruction (UUO)-induced renal fibrosis in the offspring of dams treated with lipopolysaccharide (LPS). Furthermore, it was studied the role of matrix metalloproteinases (MMPs) in these changes. Adults Wistar rats were obtained from dams submitted to LPS administration through the third part of gestation. To evaluate the role of maternal ROS, part of the dams received α-tocopherol simultaneously with LPS. Part of the offspring in each group was submitted to UUO at adulthood when sub-groups were treated with NADPH oxidase inhibitor, apocynin. Maternal LPS administration increased proteinuria, systolic arterial pressure and renal collagen deposition in adult offspring. LPS offspring rats also presented higher MMP-2 activity in parallel to a decreased renal cortical TIMP-2 content. These changes were correlated to increased amounts of TGF-β1 and NOX2. Maternal α-tocopherol treatment prevented collagen deposition and reduced arterial pressure in adult offspring. α-Tocopherol also inhibited maternal endotoxemia-induced changes in TGF-β1/NOX2/MMP-2 signaling. UUO led to increased collagen deposition in the contralateral kidneys of LPS offspring, which was correlated to increased NADPH oxidase activity and prevented by NADPH oxidase inhibition. In summary, maternal endotoxemia led to alterations in the TGF-β1/NOX2/MMP-2 signaling pathway in renal tissue concomitant with collagen deposition, therefore contributing to hypertension in adult offspring., Competing Interests: Declaration of competing interest None., (Copyright © 2020 Elsevier Inc. All rights reserved.)

Purpose: To evaluate elasticity and perfusion change associated with fibrosis in a rabbit model of unilateral ureter obstruction using shear wave elastography (SWE) and contrast-enhanced ultrasonography (CEUS)., Methods: Complete unilateral ureter obstruction by ligation was performed in the left kidney of 15 rabbits. Renal elasticity on SWE and perfusion change on CEUS at the renal cortex were measured before and after the operation. Histopathological renal fibrosis was quantified by the stained area ratio with Masson trichrome and Picrosirius red using ImageJ analysis. Renal elasticity and perfusion values were compared by the Mann-Whitney U test and Proc Mixed as a function of time. Spearman's correlation was used to analyze differences between imaging values and fibrosis., Results: The duration of imaging follow-up was up to 49 days, with interval imaging performed 1-3 times. Renal elasticity values were higher in obstructed kidneys compared to contralateral kidneys (31.0 kPa vs 16.4 kPa, p < 0.001) and increased according to postoperative time (0.46 kPa/day). With respect to renal fibrosis, SWE values were positively correlated with Masson trichrome (ρ = 0.651, p < 0.001) and Picrosirius red (ρ = 0.514, p = 0.007). Among CEUS parameters, mean transit time was negatively correlated with renal fibrosis by Masson trichrome (ρ = - 0.639, p = 0.001) and Picrosirius red (ρ = - 0.625, p = 0.001). Rise time and time to peak were positively correlated with renal fibrosis., Conclusion: Obstructive uropathy resulted in changes to both renal elasticity and perfusion. Renal fibrosis was moderately associated with increased renal cortical stiffness and both delayed and decreased cortical perfusion., Key Points: • Obstructive uropathy causes changes in elasticity and perfusion in a rabbit model. • Renal fibrosis from obstructive uropathy increases renal cortical stiffness, and both delay and decrease cortical perfusion.

Background: Kidney is one of the main target organs in Fabry disease, a lysosomal X-linked genetic disorder. Renal involvement is characterized by proteinuria and progressive chronic kidney disease leading to end-stage renal disease. Pathogenic mechanisms in the progression of renal damage in Fabry disease are not thoroughly known yet. The lysosomal Gb3 deposition is the first step of complex pathological pathways resulting in renal sclerosis/fibrosis. Our hypothesis is that Fabry disease associated cellular alterations in tubular cells induce the production of TGF-β1, which mediate transdifferentiation of renal cells into myofibroblasts resulting in fibrosis of renal tissue., Objectives: The aim of this work is to study the mechanisms leading to fibrosis in kidney from human Fabry patients., Methods: Fifteen renal biopsies from naïve Fabry patients were included. Histological and immunohistochemical analysis was carried out., Results: Positive staining for TGF-β1 was found in tubular epithelial cells in biopsies from Fabry patients. Apoptosis was determined by active caspase 3 staining in tubular and mesangial glomerular cells. Due to TGF-β1 is the main profibrotic cytokine and induces accumulation of myofibroblasts, we performed a study for its marker α-smooth muscle actin (α-SMA). This study revealed expression of α-SMA on pericytes surrounding peritubular capillaries, smooth muscle cells of blood vessels, mesangial cells and periglomerular zone. TGF-β1 is produced mainly by tubular cells in Fabry kidney biopsies probably inducing cellular trans-differentiation of renal cells into myofibroblasts. A positive staining for a marker of myofibroblasts was present, affirming the presence of those profibrotic cells., Conclusions: These results show for the first time that TGF-β1 is expressed in human renal tissue from Fabry patients, and that this profibrotic cytokine is mainly produced by proximal tubular cells. In addition both, peritubular interstitium and glomeruli, presented cells positive for myofibroblasts markers., (Copyright © 2019 Elsevier Inc. All rights reserved.)

Background: Glomerulosclerosis and tubulointerstitial fibrosis are hallmarks of chronic kidney injury leading to end-stage renal disease. Inflammatory mechanisms contribute to glomerular and interstitial scarring, including chemokine-mediated recruitment of leucocytes. In particular, accumulation of C-C chemokine receptor type 2 (CCR2)-expressing macrophages promotes renal injury and fibrotic remodelling in diseases like glomerulonephritis and diabetic nephropathy. The functional role of CCR2 in the initiation and progression of primary glomerulosclerosis induced by podocyte injury remains to be characterized., Methods: We analysed glomerular expression of CCR2 and its chemokine ligand C-C motif chemokine ligand 2 (CCL2) in human focal segmental glomerulosclerosis (FSGS). Additionally, CCL2 expression was determined in stimulated murine glomeruli and glomerular cells in vitro. To explore pro-inflammatory and profibrotic functions of CCR2 we induced adriamycin nephropathy, a murine model of FSGS, in BALB/c wild-type and Ccr2-deficient mice., Results: Glomerular expression of CCR2 and CCL2 significantly increased in human FSGS. In adriamycin-induced FSGS, progressive glomerular scarring and reduced glomerular nephrin expression was paralleled by induced glomerular expression of CCL2. Adriamycin exposure stimulated secretion of CCL2 and tumour necrosis factor-α (TNF) in isolated glomeruli and mesangial cells and CCL2 in parietal epithelial cells. In addition, TNF induced CCL2 expression in all glomerular cell populations, most prominently in podocytes. In vivo, Ccr2-deficient mice with adriamycin nephropathy showed reduced injury, macrophage and fibrocyte infiltration and inflammation in glomeruli and the tubulointerstitium. Importantly, glomerulosclerosis and tubulointerstitial fibrosis were significantly ameliorated., Conclusions: Our data indicate that CCR2 is an important mediator of glomerular injury and progression of FSGS. CCR2- targeting therapies may represent a novel approach for its treatment., (© The Author(s) 2018. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)

Background: Clinical trials have shown that empagliflozin (Empa), a sodium-glucose cotransporter 2 (SGLT2) inhibitor, promotes nephroprotective effects in diabetic patients. The mechanisms underlying nephroprotection are not completely known and it is not known whether the renal beneficial action is present even in non-diabetic kidney disease. The aim of this study was to evaluate the effect of Empa administration on the development of renal fibrosis in an experimental model of angiotensin II (Ang II)-dependent hypertension., Methods: Sprague Dawley rats (n = 31) were divided into 4 experimental groups. Ang II (200 ng/kg/min, osmotic minipumps, s.c., n = 9) or Ang II + Empa (10 mg/kg/day, per os, n = 10) were administered for 2 weeks. Control rats were treated with placebo (physiological saline, n = 6), and another group was treated with placebo plus Empa (n = 6) for the same period. Blood pressure (plethysmographic method) was measured at the beginning and at the end of the experimental protocol. After 2 weeks, the rats were euthanized and the kidneys were excised for histomorphometric evaluation of glomerular and tubulo-interstitial fibrosis and for the immunohistochemical evaluation of inflammatory infiltrates (monocytes/macrophages) and types I and IV collagen expression., Results: The administration of Ang II resulted in an increase in blood pressure (p < 0.01), glomerular (p < 0.05) and tubulo-interstitial (p < 0.01) fibrosis, renal inflammatory infiltrates (p < 0.01) and type I (p < 0.01) and type IV collagen expression (p < 0.05) compared to the control group. Treatment with Empa did not significantly modify the increase in blood pressure due to Ang II, but prevented the development of renal glomerular and tubulo-interstitial fibrosis, and the increase in inflammatory infiltrates and types I and IV collagen expression in Ang II-treated rats (p < 0.01)., Conclusions: These data demonstrate that the treatment with Empa prevents the development of renal fibrosis in Ang II-dependent hypertension. In Ang II-dependent hypertension, the anti-fibrotic effect due to SGLT2 inhibition is caused by the reduction of inflammatory infiltrates and it is independent on the modulation of blood pressure increase., (© 2020 S. Karger AG, Basel.)

Background: Polarized macrophage populations can orchestrate both inflammation of the kidney and tissue repair during CKD. Proinflammatory M1 macrophages initiate kidney injury, but mechanisms through which persistent M1-dependent kidney damage culminates in fibrosis require elucidation. Krüppel-like factor 4 (KLF4), a zinc-finger transcription factor that suppresses inflammatory signals, is an essential regulator of macrophage polarization in adipose tissues, but the effect of myeloid KLF4 on CKD progression is unknown., Methods: We used conditional mutant mice lacking KLF4 or TNF α (KLF4's downstream effector) selectively in myeloid cells to investigate macrophage KLF4's role in modulating CKD progression in two models of CKD that feature robust macrophage accumulation, nephrotoxic serum nephritis, and unilateral ureteral obstruction., Results: In these murine CKD models, KLF4 deficiency in macrophages infiltrating the kidney augmented their M1 polarization and exacerbated glomerular matrix deposition and tubular epithelial damage. During the induced injury in these models, macrophage-specific KLF4 deletion also exacerbated kidney fibrosis, with increased levels of collagen 1 and α -smooth muscle actin in the injured kidney. CD11b + Ly6C hi myeloid cells isolated from injured kidneys expressed higher levels of TNF α mRNA versus wild-type controls. In turn, mice bearing macrophage-specific deletion of TNF α exhibited decreased glomerular and tubular damage and attenuated kidney fibrosis in the models. Moreover, treatment with the TNF receptor-1 inhibitor R-7050 during nephrotoxic serum nephritis reduced damage, fibrosis, and necroptosis in wild-type mice and mice with KLF4-deficient macrophages, and abrogated the differences between the two groups in these parameters., Conclusions: These data indicate that macrophage KLF4 ameliorates CKD by mitigating TNF-dependent injury and fibrosis., (Copyright © 2019 by the American Society of Nephrology.)

Background: After bilateral kidney ischemia/reperfusion injury (IRI), monocytes infiltrate the kidney and differentiate into proinflammatory macrophages in response to the initial kidney damage, and then transition to a form that promotes kidney repair. In the setting of unilateral IRI (U-IRI), however, we have previously shown that macrophages persist beyond the time of repair and may promote fibrosis., Methods: Macrophage homing/survival signals were determined at 14 days after injury in mice subjected to U-IRI and in vitro using coculture of macrophages and tubular cells. Mice genetically engineered to lack Ccr2 and wild-type mice were treated ±CCR2 antagonist RS102895 and subjected to U-IRI to quantify macrophage accumulation, kidney fibrosis, and inflammation 14 and 30 days after the injury., Results: Failure to resolve tubular injury after U-IRI results in sustained expression of granulocyte-macrophage colony-stimulating factor by renal tubular cells, which directly stimulates expression of monocyte chemoattractant protein-1 ( Mcp-1 ) by macrophages. Analysis of CD45 + immune cells isolated from wild-type kidneys 14 days after U-IRI reveals high-level expression of the MCP-1 receptor Ccr2 . In mice lacking Ccr2 and wild-type mice treated with RS102895, the numbers of macrophages, dendritic cells, and T cell decreased following U-IRI, as did the expression of profibrotic growth factors and proimflammatory cytokines. This results in a reduction in extracellular matrix and kidney injury markers., Conclusions: GM-CSF-induced MCP-1/CCR2 signaling plays an important role in the cross-talk between injured tubular cells and infiltrating immune cells and myofibroblasts, and promotes sustained inflammation and tubular injury with progressive interstitial fibrosis in the late stages of U-IRI., (Copyright © 2019 by the American Society of Nephrology.)

Background: Renal fibrosis is a key pathological feature and final common pathway leading to end-stage kidney failure in many chronic kidney diseases. Myofibroblast is the master player in renal fibrosis. However, myofibroblasts are heterogeneous. Recent studies show that bone marrow-derived macrophages transform into myofibroblasts by transforming growth factor (TGF)-β-induced macrophage-myofibroblast transition (MMT) in renal fibrosis., Methods: TGF-β signaling was redirected by inhibition of β-catenin/T-cell factor (TCF) to increase β-catenin/Foxo in bone marrow-derived macrophages. A kidney fibrosis model of unilateral ureteral obstruction was performed in EGFP bone marrow chimera mouse. MMT was examined by flow cytometry analysis of GFP+F4/80+α-SMA+ cells from unilateral ureteral obstruction (UUO) kidney, and by immunofluorescent staining of bone marrow-derived macrophages in vitro. Inflammatory and anti-inflammatory cytokines were analysis by enzyme-linked immunosorbent assay., Results: Inhibition of β-catenin/TCF by ICG-001 combined with TGF-β1 treatment increased β-catenin/Foxo1, reduced the MMT and inflammatory cytokine production by bone marrow-derived macrophages, and thereby, reduced kidney fibrosis in the UUO model., Conclusions: Our results demonstrate that diversion of β-catenin from TCF to Foxo1-mediated transcription not only inhibits the β-catenin/TCF-mediated fibrotic effect of TGF-β, but also enhances its anti-inflammatory action, allowing therapeutic use of TGF-β to reduce both inflammation and fibrosis at least partially by changing the fate of bone marrow-derived macrophages., (© The Author(s) 2018. Published by Oxford University Press on behalf of ERA-EDTA. All rights reserved.)

Introduction: Renal fibrosis is the end point of a process that begins at transplant, with ischemia reperfusion and early inflammation, and progresses over time with immunological and non-immunological phenomena. Early identification of morphological markers and intervention could improve graft function and survival., Objective: to evaluate the correlation between intensity and specificity of pre-transplant anti-HLA antibodies and kidney allograft pathology in order to identify early risk factors or markers of allograft dysfunction., Methods: A retrospective cohort of kidney transplant recipients with pre-transplant anti-HLA antibodies who underwent graft biopsy within the first two years post-transplant was divided into two groups according to the specificity of anti-HLA antibodies: nonspecific (non-DSA, n = 29) and specific (DSA+, n = 16). Kidney graft pathology, renal function, and proteinuria were analyzed., Results: general characteristics were similar in both groups, except for the higher dose of thymoglobulin in DSA+ group (p < 0.05). The non-DSA group had higher scores for glomerulosclerosis, interstitial inflammation (i) and interstitial fibrosis (ci) (p < 0.05) and higher incidence of cell-mediated acute rejection. No statistical difference in incidence of antibody-mediated rejection, renal function, and proteinuria was observed during follow up., Discussion and Conclusions: the difference in inflammation scores and interstitial fibrosis may be associated to the higher incidence of acute cell-mediated rejection and polyomavirus nephropathy in the Non-DSA group. We also should take into account the protective effect of higher doses of thymoglobulin, reducing ischemia reperfusion injury in the DSA+ group. The short follow-up might have been insufficient to detect long-term changes in allograft tissue, renal function, and proteinuria.

Diabetic Nephropathy (DN) is a chronic complication of diabetes and the primary cause of end stage renal disease. Differential diagnosis for DN requires invasive histological investigation, thus there is need for non-invasive biomarkers to discriminate among different histological lesions in diabetic patients. With the aim to identify a pattern of differentially expressed miRNAs in kidney biopsies of DN patients, we assayed miRNA expression in kidney biopsies from DN patients, diabetic patients with membranous nephropathy and patients with normal histology. Nine miRNAs were differentially expressed among the three groups, and 2 miRNAs (miR-27b-3p and miR-1228-3p) showed interaction with an ubiquitin-conjugating E2 enzyme variant (UBE2v1). UBE2v1 mediates the formation of lysine 63-linked ubiquitin chains, a mechanism we previously showed as involved in DN kidney fibrosis. Both miRNAs were validated as down-regulated in biopsies and urines of DN patients, possibly affected by DNA methylation. Interestingly, the urinary levels of both miRNAs could also discriminate among different degrees of renal fibrosis. Finally, we showed that the combined urinary expression of both miRNAs was also able to discriminate DN patients from other glomerulonephritides in diabetic patients. In conclusion we identified two miRNAs potentially useful as candidate biomarkers of tubular-interstitial fibrosis in diabetic patients with DN.

IL-9 is a pleiotropic cytokine, recently recognized as belonging to Th9 cells that are involved in various pathologies. We aimed to evaluate the role of IL-9 in the course of hepatic and renal fibrosis. Female C57BL/6 mice were treated subcutaneously with IL-9 10 ng/mouse and 20 ng/mouse for 40 days, alternating every 5 days each application, the negative control of which was treated with PBS and positive control with CCL 4 . IL-9 demonstrated fibrogenic activity, leading to increased collagen I and III deposition in both liver and kidney, as well as triggering lobular hepatitis. In addition, IL-9 induced an inflammatory response with recruitment of lymphocytes, neutrophils, and macrophages to both organs. The inflammation was present in the region of the portal and parenchymal zone in the liver and in the cortical and medullary zone in the kidney. IL-9 deregulated liver and kidney antioxidant activities. Our results showed that IL-9 was able to promote hepatorenal dysfunction. Moreover, IL-9 poses as a promising target for therapeutic interventions.

Introduction: IgA nephropathy (IgAN) is the commonest global cause of glomerulonephritis. Extent of fibrosis, tubular atrophy and glomerulosclerosis predict renal function decline. Extent of renal fibrosis is assessed with renal biopsy which is invasive and prone to sampling error. We assessed the utility of non-contrast native T1 mapping of the kidney in patients with IgAN for assessment of renal fibrosis., Methods: Renal native T1 mapping was undertaken in 20 patients with IgAN and 10 healthy subjects. Ten IgAN patients had a second scan to assess test-retest reproducibility of the technique. Native T1 times were compared to markers of disease severity including degree of fibrosis, eGFR, rate of eGFR decline and proteinuria., Results: All patients tolerated the MRI scan and analysable quality T1 maps were acquired in at least one kidney in all subjects. Cortical T1 times were significantly longer in patients with IgAN than healthy subjects (1540 ms ± 110 ms versus 1446 ± 88 ms, p = 0.038). There was excellent test-retest reproducibility of the technique, with Coefficient-of-variability of axial and coronal T1 mapping analysis being 2.9 and 3.7% respectively. T1 correlated with eGFR and proteinuria (r = - 0.444, p = 0.016; r = 0.533, p = 0.003 respectively). Patients with an eGFR decline > 2 ml/min/year had increased T1 times compared to those with a decline < 2 ml/min/year (1615 ± 135 ms versus 1516 ± 87 ms, p = 0.068), and T1 time was also higher in patients with a histological 'T'-score of > 0, compared to those with a 'T'-score of 0 (1575 ± 106 ms versus 1496 ± 105 ms, p = 0.131), though not to significance., Conclusions: Cortical native T1 time is significantly increased in patients with IgAN compared to healthy subjects and correlates with markers of renal disease. Reproducibility of renal T1 mapping is excellent. This study highlights the potential utility of native T1 mapping in IgAN and other progressive nephropathies, and larger prospective studies are warranted.

Background: The pathology change of renal tubulointerstitial fibrosis is a critical feature of chronic kidney disease (CKD), regardless of the primary insults. The infiltration of inflammatory cells and the consecutive secretion of profibrotic factors are frequently and conspicuously observed during the development of renal fibrosis. Icariin, an active polyphenol of the Epimedium genus, has been found to alleviate the symptoms of chronic diseases like diabetes, neurodegeneration, and heart and renal diseases. The effect and mechanism of icariin on the prevention of CKD-associated renal fibrosis still needed clarification., Purpose: The aims of this study were to investigate whether icariin treatment improves the development of CKD-associated renal fibrosis and its possible mechanism., Methods: An experimental unilateral ureteral obstruction (UUO)-induced chronic renal fibrosis mouse model was used. Mice were orally administered with icariin (20 mg/kg/day) for 3 consecutive days before and 14 consecutive days after UUO surgery., Results: The pathological changes, collagen deposition, and protein expressions of profibrotic factors (transforming growth factor-β and connective tissue growth factor) and fibrotic markers (α-smooth muscle actin and fibronectin), which were significantly elevated in the kidneys of UUO mice, could be significantly reversed by icariin treatment. Icariin treatment also significantly inhibited the increased Smad2/3 and decreased E-cadherin protein expressions in the kidneys of UUO mice. Icariin treatment prominently mitigated the protein expression of proinflammatory factors like nuclear factor-κB, cyclooxygenase-2, interleukin 1-β and prooxidative enzyme (NADPH oxidase-4), and it increased the protein expression of antioxidative enzymes (superoxide dismutase and catalase)., Conclusion: Icariin treatment protects against CKD-associated renal fibrosis via its antifibrotic and anti-inflammatory properties. Icariin may serve as a therapeutic agent in the prevention of CKD-associated renal fibrosis., (Copyright © 2019 Elsevier GmbH. All rights reserved.)

Background/aims: Renal dysfunction or renal failure is a common complication in left ventricular assist device (LVAD) recipients and is associated with reduced survival. To date, serum creatinine and glomerular filtration rate (GFR) are used for the evaluation of kidney function. However, serum creatinine and GFR have limitations. The objective of our study is to assess the levels of kidney biomarkers in LVAD recipients compared to heart failure patients and healthy controls and to examine their association with conventional clinical biomarkers., Methods: The biomarkers neutrophil gelatinase-associated lipocalin (NGAL), kidney injury molecule-1 (KIM-1), plasminogen activator inhibitor-1 (PAI-1), and adiponectin were assessed in 51 participants: 19 heart failure patients, 16 LVAD recipients, and 16 healthy controls. Linear regressions were performed to assess whether demographic and clinical variables predict the levels of biomarkers that are associated with acute kidney injury and the risk of chronic kidney disease., Results: The levels of NGAL and adiponectin were higher in LVAD recipients and patients with heart failure as compared with healthy controls. The levels of PAI-1 and KIM-1 were not elevated in LVAD recipients. The results of linear regression analysis indicated that when controlling for the effect of CRP and BNP, 40.1% of the variance in NGAL levels can be explained by GFR (R2 = 0.401, F = 5.56, p = 0.005), while CRP can explain 35.3% of the variance in adiponectin levels (R2 = 0.353, F = 4.55, p = 0.01), when controlling for the effect of BNP and GFR., Conclusions: The levels of NGAL and adiponectin were augmented in LVAD recipients, suggesting that renal functions were not restored with circulatory support. Larger studies should assess the predictability of these biomarkers of renal dysfunction in LVAD recipients., (© 2019 S. Karger AG, Basel.)

Dysregulation of the renin-angiotensin system leads to systemic hypertension and maladaptive fibrosis in various organs. We showed recently that myocardial fibrosis and the loss of cardiac function in mice with transverse aortic constriction (TAC) could be averted by treatment with the caveolin-1 scaffolding domain (CSD) peptide. Here, we used angiotensin II (AngII) infusion (2.1 mg/kg/day for 2 wk) in mice as a second model to confirm and extend our observations on the beneficial effects of CSD on heart and kidney disease. AngII caused cardiac hypertrophy (increased heart weight to body weight ratio (HW/BW) and cardiomyocyte cross-sectional area); fibrosis in heart and kidney (increased levels of collagen I and heat shock protein-47 (HSP47)); and vascular leakage (increased levels of IgG in heart and kidney). Echocardiograms of AngII-infused mice showed increased left ventricular posterior wall thickness (pWTh) and isovolumic relaxation time (IVRT), and decreased ejection fraction (EF), stroke volume (SV), and cardiac output (CO). CSD treatment (i.p. injections, 50 μg/mouse/day) of AngII-infused mice significantly suppressed all of these pathological changes in fibrosis, hypertrophy, vascular leakage, and ventricular function. AngII infusion increased β1 and β3 integrin levels and activated Pyk2 in both heart and kidney. These changes were also suppressed by CSD. Finally, bone marrow cell (BMC) isolated from AngII-infused mice showed hyper-migration toward SDF1. When AngII-infused mice were treated with CSD, BMC migration was reduced to the basal level observed in cells from control mice. Importantly, CSD did not affect the AngII-induced increase in blood pressure (BP), indicating that the beneficial effects of CSD were not mediated via normalization of BP. These results strongly indicate that CSD suppresses AngII-induced pathological changes in mice, suggesting that CSD can be developed as a treatment for patients with hypertension and pressure overload-induced heart failure., Competing Interests: This study was funded in part by a Sponsored Research Agreement from Lung Therapeutics, Inc., to Dr. Stanley Hoffman. Lung Therapeutics has also licensed a use patent (no. 8,058,227) issued to the Medical University of South Carolina for the caveolin-1 scaffolding domain peptide as a treatment for fibrotic diseases on which Drs. Hoffman and Tourkina are named coinventors. Lung Therapeutics played no role in the study design; collection, analysis, and interpretation of data; writing of the paper; and/or decision to submit for publication. Our partial funding by Lung Therapeutics does not affect our adherence to all the PLOS ONE policies on sharing data and materials, as detailed online in the guide for authors.

TGF-β signals through a receptor complex composed of 2 type I and 2 type II (TGF-βRII) subunits. We investigated the role of macrophage TGF-β signaling in fibrosis after AKI in mice with selective monocyte/macrophage TGF-βRII deletion (macrophage TGF-βRII-/- mice). Four weeks after injury, renal TGF-β1 expression and fibrosis were higher in WT mice than macrophage TGF-βRII-/- mice, which had decreased renal macrophages. The in vitro chemotactic response to f-Met-Leu-Phe was comparable between bone marrow-derived monocytes (BMMs) from WT and macrophage TGF-βRII-/- mice, but TGF-βRII-/- BMMs did not respond to TGF-β. We then implanted Matrigel plugs suffused with either f-Met-Leu-Phe or TGF-β1 into WT or macrophage TGF-βRII-/- mice. After 6 days, f-Met-Leu-Phe induced similar macrophage infiltration into the Matrigel plugs of WT and macrophage TGF-βRII-/- mice, but TGF-β induced infiltration only in WT mice. We further determined the number of labeled WT or TGF-βRII-/- BMMs infiltrating into WT kidneys 20 days after ischemic injury. There were more labeled WT BMMs than TGF-βRII-/- BMMs. Therefore, macrophage TGF-βRII deletion protects against the development of tubulointerstitial fibrosis following severe ischemic renal injury. Chemoattraction of macrophages to the injured kidney through a TGF-β/TGF-βRII axis is a heretofore undescribed mechanism by which TGF-β can mediate renal fibrosis during progressive renal injury.

IL-22, a member of the IL-10 cytokine family, accelerates tubule regeneration upon acute kidney injury, hence we speculated on a protective role also in chronic kidney disease. We quantified intrarenal IL-22 expression after unilateral ureteral (UUO) in wild-type mice and performed UUO in IL-22 knock-out animals. Obstruction phenotypic differences between IL22 +/+ and IL22 -/- mice were assessed by histology, immunohistochemistry, immunofluorescence as well as western blotting and reverse-transcriptase quantitative PCR ex vivo. Additionally, we performed in vitro experiments using both murine and human tubular cells to characterize IL-22 effects in epithelial healing. We found increasing IL-22 positivity in infiltrating immune cells over time upon UUO in wild-type mice. UUO in IL22 -/- mice caused more tubular cell injury as defined by TUNEL positive cells and loss of tetragonolobus lectin staining. Instead, tubular dilation, loss of CD31+ perivascular capillaries, and interstitial fibrosis were independent of the Il22 genotype as assessed by standard histology, immunostaining, and mRNA expression profiling. In vitro experiments showed that recombinant human IL-22 significantly enhanced human tubular epithelial cell proliferation and wound closure upon mechanical injury, and electric cell-substrate impedance sensing studies revealed that recombinant IL-22 sustained tubular epithelial barrier function upon injury. In contrast, IL-22 had no such direct effects on human fibroblasts. Together, in progressive kidney remodeling upon UUO, infiltrating immune cells secrete IL-22, which augments tubular epithelial integrity and epithelial barrier function, but does not affect vascular rarefaction or fibrogenesis. We conclude that IL-22 could represent a molecular target to specifically modulate tubular atrophy., (© 2018 The Authors. Physiological Reports published by Wiley Periodicals, Inc. on behalf of The Physiological Society and the American Physiological Society.)

Objectives: The most important treatment strategy for obstructive nephropathy is to protect renal tissue from the deleterious effects of fibrosis. Therefore, we sought to investigate the renoprotective effects of darbepoetin alfa on unilateral ureteral obstructions., Methods: We used 12 female and 12 male 3-monthold Wistar rats weighing between 250 and 350 g. The rats were divided equally into sham, darbepoetin and control groups. With the exception of the sham group, left unilateral obstructions were applied to all of the rats. The darbepoetin group received perioperative darbepoetin alfa at a dose of 10 mg/kg. The rats were sacrificed on postoperative day 7, and 3-cc blood samples and bilateral renal specimens were collected from each rat., Results: Renal ectasia was observed significantly less frequently in the darbepoetin group than the obstruction group (p<0.001). Additionally, the uptake rates of cortical TNF and medullary SMA in the darbepoetin group were comparable to those in the sham group but lower than those in the ureteral obstruction group (p<0.001 and p<0.008, respectively). When biomarkers of renal injury, including cystatin-C, malondialdehyde, and B2 microglobulin, were evaluated in combination, B2 microglobulin was found at higher levels in the ureteral obstruction group (p<0.004)., Conclusion: As we know pelvicalyceal ectasia reflects intrapelvic pressure into renal tubular system via renal reflux. Therefore pelvicalyceal ectasia can be used as an indicator of renal tubular pressure. Although as a limitation of our study, renal tubular pressure was not quantitatively evaluated, parallelism between levels of renal ectasia detected in the rats of the sham, and DPO groups can predict that this drug (darbepoetin-a) can decrease renal tubular pressure in acute ureteral obstruction. Moreover, B2 microglobulin levels in the sham, and DPO groups differed from those of ureteral obstruction group, which suggested that DPO does not impair renal perfusion in addition to its decreasing effects on renal tubular pressure. We think that in countries with higher incidence rates of stone disease similar to our country, DPO may be used among medical treatment alternatives, which aim to preserve renal reserve.

In damaged kidneys, increased extracellular matrix (ECM) and tissue stiffness stimulate kidney fibrosis through incompletely characterized molecular mechanisms. The transcriptional coactivators yes-associated protein (Yap) and transcriptional coactivator with PDZ-binding motif (Taz) function as mechanosensors in cancer cells and have been implicated in the regulation of myofibroblasts in the kidney. We hypothesized that the development of kidney fibrosis depends on Yap-induced activation and proliferation of kidney fibroblasts. In mice, Yap expression increased in renal fibroblasts after unilateral ureteral obstruction (UUO), in association with worsening of interstitial fibrosis. In cultured fibroblasts, inhibition of Yap/Taz signaling blocked TGF- β 1-induced fibroblast-to-myofibroblast transformation and ECM production, whereas constitutive activation of Yap promoted fibroblast transformation and ECM production even in the absence of TGF- β 1. Moreover, in the absence of TGF- β 1, fibroblasts seeded on a stiffened ECM transformed into myofibroblasts in a process dependent on the activation of Yap. In mice with UUO, the Yap inhibitor verteporfin reduced interstitial fibrosis. Furthermore, Gli1 + cell-specific knockout of Yap/Taz in mice suppressed UUO-induced ECM deposition, myofibroblast accumulation, and interstitial fibrosis. In a UUO-release model, induction of Gli1 + cell-specific Yap/Taz knockout partially reversed the development of interstitial fibrosis. Thus, in the kidney, Yap is a tissue mechanosensor that can be activated by ECM and transforms fibroblasts into myofibroblasts; the interaction of Yap/Taz and ECM forms a feed-forward loop resulting in kidney fibrosis. Identifying mechanisms that interrupt this profibrotic cycle could lead to the development of anti-fibrosis therapy., (Copyright © 2017 by the American Society of Nephrology.)

The normal response to kidney injury includes a robust inflammatory infiltrate of PMNs and macrophages. We previously showed that the small secreted protein breast regression protein-39 (BRP-39), also known as chitinase 3-like 1 (CHI3L1) and encoded by the Chi3l1 gene, is expressed at high levels by macrophages during the early stages of kidney repair and promotes tubular cell survival via IL-13 receptor α 2 (IL13R α 2)-mediated signaling. Here, we investigated the role of BRP-39 in profibrotic responses after AKI. In wild-type mice, failure to resolve tubular injury after unilateral ischemia-reperfusion injury (U-IRI) led to sustained low-level Chi3l1 mRNA expression by renal cells and promoted macrophage persistence and severe interstitial fibrosis. Analysis of macrophages isolated from wild-type kidneys 14 days after U-IRI revealed high-level expression of the profibrotic BRP-39 receptor Ptgdr2 / Crth2 and expression of the profibrotic markers Lgals3 , Pdgfb , Egf , and Tgfb In comparison, injured kidneys from mice lacking BRP-39 had significantly fewer macrophages, reduced expression of profibrotic growth factors, and decreased accumulation of extracellular matrix. BRP-39 depletion did not affect myofibroblast accumulation but did attenuate myofibroblast expression of Col1a1 , Col3a1 , and Fn1 Together, these results identify BRP-39 as an important activator of macrophage-myofibroblast crosstalk and profibrotic signaling in the setting of maladaptive kidney repair., (Copyright © 2017 by the American Society of Nephrology.)

Kidney fibrosis is the histologic manifestation of CKD. Sustained activation of developmental pathways, such as Notch, in tubule epithelial cells has been shown to have a key role in fibrosis development. The molecular mechanism of Notch-induced fibrosis, however, remains poorly understood. Here, we show that, that expression of peroxisomal proliferation g-coactivator (PGC-1 α ) and fatty acid oxidation-related genes are lower in mice expressing active Notch1 in tubular epithelial cells (Pax8-rtTA/ ICN1 ) compared to littermate controls. Chromatin immunoprecipitation assays revealed that the Notch target gene Hes1 directly binds to the regulatory region of PGC-1 α Compared with Pax8-rtTA/ICN1 transgenic animals, Pax8-rtTA/ICN1/Ppargc1a transgenic mice showed improvement of renal structural alterations (on histology) and molecular defect (expression of profibrotic genes). Overexpression of PGC-1 α restored mitochondrial content and reversed the fatty acid oxidation defect induced by Notch overexpression in vitro in tubule cells. Furthermore, compared with Pax8-rtTA/ICN1 mice, Pax8-rtTA/ICN1/Ppargc1a mice exhibited improvement in renal fatty acid oxidation gene expression and apoptosis. Our results show that metabolic dysregulation has a key role in kidney fibrosis induced by sustained activation of the Notch developmental pathway and can be ameliorated by PGC-1 α ., (Copyright © 2017 by the American Society of Nephrology.)

The (pro)renin receptor (PRR) is a transmembrane protein with multiple functions. However, its regulation and role in the pathogenesis of CKD remain poorly defined. Here, we report that PRR is a downstream target and an essential component of Wnt/ β -catenin signaling. In mouse models, induction of CKD by ischemia-reperfusion injury (IRI), adriamycin, or angiotensin II infusion upregulated PRR expression in kidney tubular epithelium. Immunohistochemical staining of kidney biopsy specimens also revealed induction of renal PRR in human CKD. Overexpression of either Wnt1 or β -catenin induced PRR mRNA and protein expression in vitro Notably, forced expression of PRR potentiated Wnt1-mediated β -catenin activation and augmented the expression of downstream targets such as fibronectin, plasminogen activator inhibitor 1, and α -smooth muscle actin ( α -SMA). Conversely, knockdown of PRR by siRNA abolished β -catenin activation. PRR potentiation of Wnt/ β -catenin signaling did not require renin, but required vacuolar H + ATPase activity. In the mouse model of IRI, transfection with PRR or Wnt1 expression vectors promoted β -catenin activation, aggravated kidney dysfunction, and worsened renal inflammation and fibrotic lesions. Coexpression of PRR and Wnt1 had a synergistic effect. In contrast, knockdown of PRR expression ameliorated kidney injury and fibrosis after IRI. These results indicate that PRR is both a downstream target and a crucial element in Wnt signal transmission. We conclude that PRR can promote kidney injury and fibrosis by amplifying Wnt/ β -catenin signaling., (Copyright © 2017 by the American Society of Nephrology.)

Cell-cell communication via Wnt ligands is necessary in regulating embryonic development and has been implicated in CKD. Because Wnt ligands are ubiquitously expressed, the exact cellular source of the Wnts involved in CKD remains undefined. To address this issue, we generated two conditional knockout mouse lines in which Wntless (Wls), a dedicated cargo receptor that is obligatory for Wnt secretion, was selectively ablated in tubular epithelial cells or interstitial fibroblasts. Blockade of Wnt secretion by genetic deletion of Wls in renal tubules markedly inhibited myofibroblast activation and reduced renal fibrosis after unilateral ureteral obstruction. This effect associated with decreased activation of β -catenin and downstream gene expression and preserved tubular epithelial integrity. In contrast, fibroblast-specific deletion of Wls exhibited little effect on the severity of renal fibrosis after obstructive or ischemia-reperfusion injury. In vitro , incubation of normal rat kidney fibroblasts with tubule-derived Wnts promoted fibroblast proliferation and activation. Furthermore, compared with kidney specimens from patients without CKD, biopsy specimens from patients with CKD also displayed increased expression of multiple Wnt proteins, predominantly in renal tubular epithelium. These results illustrate that tubule-derived Wnts have an essential role in promoting fibroblast activation and kidney fibrosis via epithelial-mesenchymal communication., (Copyright © 2017 by the American Society of Nephrology.)

IL-36 cytokines are proinflammatory and have an important role in innate and adaptive immunity, but the role of IL-36 signaling in renal tubulointerstitial lesions (TILs), a major prognostic feature of renal inflammation and fibrosis, remains undetermined. In this study, increased IL-36 α expression detected in renal biopsy specimens and urine samples from patients with renal TILs correlated with renal function impairment. We confirmed the increased expression of IL-36 α in the renal tubular epithelial cells of a mouse model of unilateral ureteral obstruction (UUO) and related cell models using mechanically induced pressure, oxidative stress, or high mobility group box 1. In contrast, the kidneys of IL-36 receptor (IL-36R) knockout mice exhibit attenuated TILs after UUO. Compared with UUO-treated wild-type mice, UUO-treated IL-36 knockout mice exhibited markedly reduced NLRP3 inflammasome activation and macrophage/T cell infiltration in the kidney and T cell activation in the renal draining lymph nodes. In vitro , recombinant IL-36 α facilitated NLRP3 inflammasome activation in renal tubular epithelial cells, macrophages, and dendritic cells and enhanced dendritic cell-induced T cell proliferation and Th17 differentiation. Furthermore, deficiency of IL-23, which was diminished in IL-36R knockout UUO mice, also reduced renal TIL formation in UUO mice. In wild-type mice, administration of an IL-36R antagonist after UUO reproduced the results obtained in UUO-treated IL-36R knockout mice. We propose that IL-36 signaling contributes to the pathogenesis of renal TILs through the activation of the NLRP3 inflammasome and IL-23/IL-17 axis., (Copyright © 2017 by the American Society of Nephrology.)

Interstitial fibrosis is an important contributor to graft loss in chronic renal allograft injury. Inflammatory macrophages are associated with fibrosis in renal allografts, but how these cells contribute to this damaging response is not clearly understood. Here, we investigated the role of macrophage-to-myofibroblast transition in interstitial fibrosis in human and experimental chronic renal allograft injury. In biopsy specimens from patients with active chronic allograft rejection, we identified cells undergoing macrophage-to-myofibroblast transition by the coexpression of macrophage (CD68) and myofibroblast ( α -smooth muscle actin [ α -SMA]) markers. CD68 + / α -SMA + cells accounted for approximately 50% of the myofibroblast population, and the number of these cells correlated with allograft function and the severity of interstitial fibrosis. Similarly, in C57BL/6J mice with a BALB/c renal allograft, cells coexpressing macrophage markers (CD68 or F4/80) and α -SMA composed a significant population in the interstitium of allografts undergoing chronic rejection. Fate-mapping in Lyz2-Cre/Rosa26-Tomato mice showed that approximately half of α -SMA + myofibroblasts in renal allografts originated from recipient bone marrow-derived macrophages. Knockout of Smad3 protected against interstitial fibrosis in renal allografts and substantially reduced the number of macrophage-to-myofibroblast transition cells. Furthermore, the majority of macrophage-to-myofibroblast transition cells in human and experimental renal allograft rejection coexpressed the M2-type macrophage marker CD206, and this expression was considerably reduced in Smad3 -knockout recipients. In conclusion, our studies indicate that macrophage-to-myofibroblast transition contributes to interstitial fibrosis in chronic renal allograft injury. Moreover, the transition of bone marrow-derived M2-type macrophages to myofibroblasts in the renal allograft is regulated via a Smad3-dependent mechanism., (Copyright © 2017 by the American Society of Nephrology.)

Activated fibroblasts are deemed the main executors of organ fibrosis. However, regulation of the pathologic functions of these cells in vivo is poorly understood. PDGF receptor β (PDGFR β ) is highly expressed in activated pericytes, a main source of fibroblasts. Studies using a PDGFR β promoter-driven Cre system to delete α v integrins in activated fibroblasts identified these integrins as core regulators of fibroblast activity across solid organs, including the kidneys. Here, we used the same PDGFR β -Cre line to isolate and study renal fibroblasts ex vivo We found that renal fibroblasts express three α v integrins, namely α v β 1, α v β 3, and α v β 5. Blockade of α v β 1 prevented direct binding of fibroblasts to the latency-associated peptide of TGF- β 1 and prevented activation of the latent TGF- β complex. Continuous administration of a recently described potent small molecule inhibitor of α v β 1, compound 8, starting the day of unilateral ureteral obstruction operation, inhibited collagen deposition in the kidneys of mice 14 days later. Compound 8 also effectively attenuated renal failure, as measured by BUN levels in mice fed an adenine diet known to cause renal injury followed by fibrosis. Inhibition of α v β 1 integrin could thus hold promise as a therapeutic intervention in CKD characterized by renal fibrosis., (Copyright © 2017 by the American Society of Nephrology.)

Connective tissue growth factor (CTGF), a matrix-associated protein with four distinct cytokine binding domains, has roles in vasculogenesis, wound healing responses, and fibrogenesis and is upregulated in fibroblasts and myofibroblasts in disease. Here, we investigated the role of CTGF in fibrogenic cells. In mice, tissue-specific inducible overexpression of CTGF by kidney pericytes and fibroblasts had no bearing on nephrogenesis or kidney homeostasis but exacerbated inflammation and fibrosis after ureteral obstruction. These effects required the WNT receptor LDL receptor-related protein 6 (LRP6). Additionally, pericytes isolated from these mice became hypermigratory and hyperproliferative on overexpression of CTGF. CTGF is cleaved in vivo into distinct domains. Treatment with recombinant domain 1, 1+2 (N terminus), or 4 (C terminus) independently activated myofibroblast differentiation and wound healing responses in cultured pericytes, but domain 4 showed the broadest profibrotic activity. Domain 4 exhibited low-affinity binding to LRP6 in in vitro binding assays, and inhibition of LRP6 or critical signaling cascades downstream of LRP6, including JNK and WNT/ β -catenin, inhibited the biologic activity of domain 4. Administration of blocking antibodies specifically against CTGF domain 4 or recombinant Dickkopf-related protein-1, an endogenous inhibitor of LRP6, effectively inhibited inflammation and fibrosis associated with ureteral obstruction in vivo Therefore, domain 4 of CTGF and the WNT signaling pathway are important new targets in fibrosis., (Copyright © 2017 by the American Society of Nephrology.)

Salt-sensitive hypertension (SSHT) leads to kidney interstitial fibrosis. However, the potential mechanisms leading to renal fibrosis have not been well investigated. In present study, Dahl salt-sensitive (DS) rats were divided into three groups: normal salt diet (DSN), high salt diet (DSH) and high salt diet treated with hydrochlorothiazide (HCTZ) (DSH + HCTZ). A significant increase in systolic blood pressure (SBP) was observed 3 weeks after initiating the high salt diet, and marked histological alterations were observed in DSH rats. DSH rats showed obvious podocyte injury, peritubular capillary (PTC) loss, macrophage infiltration, and changes in apoptosis and cell proliferation. Moreover, Wnt/β-catenin signaling was significantly activated in DSH rats. However, HCTZ administration attenuated these changes with decreased SBP. In addition, increased renal and urinary Wnt4 expression was detected with time in DSH rats and was closely correlated with histopathological alterations. Furthermore, these alterations were also confirmed by clinical study. In conclusion, the present study provides novel insight into the mechanisms related to PTC loss, macrophage infiltration and Wnt/β-catenin signaling in SSHT-induced renal injury and fibrosis. Therefore, multi-target therapeutic strategies may be the most effective in preventing these pathological processes. Moreover, urinary Wnt4 may be a noninvasive biomarker for monitoring renal injury after hypertension.

Maladaptive repair after AKI may lead to progressive fibrosis and decline in kidney function. Sphingosine 1-phosphate has an important role in kidney injury and pleiotropic effects in fibrosis. We investigated the involvement of sphingosine kinase 1 and 2 (SphK1 and SphK2), which phosphorylate sphingosine to produce sphingosine 1-phosphate, in kidney fibrosis induced by folic acid (FA) or unilateral ischemia-reperfusion injury. Analysis of Masson trichrome staining and fibrotic marker protein and mRNA expression 14 days after AKI revealed that wild-type (WT) and Sphk1 -/- mice exhibited more kidney fibrosis than Sphk2 -/- mice. Furthermore, kidneys of FA-treated WT and Sphk1 -/- mice had greater immune cell infiltration and expression of fibrotic and inflammatory markers than kidneys of FA-treated Sphk2 -/- mice. In contrast, kidneys of Sphk2 -/- mice exhibited greater expression of Ifng and IFN- γ -responsive genes ( Cxcl9 and Cxcl10 ) than kidneys of WT or Sphk1 -/- mice did at this time point. Splenic T cells from untreated Sphk2 -/- mice were hyperproliferative and produced more IFN- γ than did those of WT or Sphk1 -/- mice. IFN- γ blocking antibody administered to Sphk2 -/- mice or deletion of Ifng ( Sphk2 -/- Ifng -/- mice) blocked the protective effect of SphK2 deficiency in fibrosis. Moreover, adoptive transfer of Sphk2 -/- (but not Sphk2 -/- Ifng -/- ) CD4 T cells into WT mice blocked FA-induced fibrosis. Finally, a selective SphK2 inhibitor blocked FA-induced kidney fibrosis in WT mice. These studies demonstrate that SphK2 inhibition may serve as a novel therapeutic approach for attenuating kidney fibrosis., (Copyright © 2017 by the American Society of Nephrology.)

Kidney fibrosis initiates at certain focal sites in which the fibrogenic niche provides a specialized microenvironment that facilitates fibroblast activation and proliferation. However, the molecular identity of these fibrogenic niches is poorly characterized. Here, we determined whether tenascin-C (TNC), an extracellular matrix glycoprotein, is a component of the fibrogenic niche in kidney fibrosis. In vivo , TNC expression increased rapidly in kidneys subjected to unilateral ureteral obstruction or ischemia/reperfusion injury and predominantly localized at the foci rich in fibroblasts in renal interstitium. In vitro , TNC selectively promoted renal interstitial fibroblast proliferation, bromodeoxyuridine incorporation, and the expression of proliferation-related genes. The mitogenic activity of TNC required the integrin/focal adhesion kinase/mitogen-activated protein kinase signaling cascade. Using decellularized extracellular matrix scaffolds, we found that TNC-enriched scaffolds facilitated fibroblast proliferation, whereas TNC-deprived scaffolds inhibited proliferation. Matrix scaffold prepared from fibrotic kidney also promoted greater ex vivo fibroblast proliferation than did scaffolds prepared from healthy kidney. Conversely, small interfering RNA-mediated knockdown of TNC in vivo repressed injury-induced fibroblast expansion and renal fibrosis. These studies identify TNC as a major constituent of the fibrogenic niche that promotes fibroblast proliferation, and illustrate a pivotal role for the TNC-enriched microenvironment in kidney fibrogenesis., (Copyright © 2017 by the American Society of Nephrology.)

Development of CKD secondary to chronic heart failure (CHF), known as cardiorenal syndrome type 2 (CRS2), clinically associates with organ failure and reduced survival. Heart and kidney damage in CRS2 results predominantly from chronic stimulation of G protein-coupled receptors (GPCRs), including adrenergic and endothelin (ET) receptors, after elevated neurohormonal signaling of the sympathetic nervous system and the downstream ET system, respectively. Although we and others have shown that chronic GPCR stimulation and the consequent upregulated interaction between the G-protein βγ-subunit (Gβγ), GPCR-kinase 2, and β-arrestin are central to various cardiovascular diseases, the role of such alterations in kidney diseases remains largely unknown. We investigated the possible salutary effect of renal GPCR-Gβγ inhibition in CKD developed in a clinically relevant murine model of nonischemic hypertrophic CHF, transverse aortic constriction (TAC). By 12 weeks after TAC, mice developed CKD secondary to CHF associated with elevated renal GPCR-Gβγ signaling and ET system expression. Notably, systemic pharmacologic Gβγ inhibition by gallein, which we previously showed alleviates CHF in this model, attenuated these pathologic renal changes. To investigate a direct effect of gallein on the kidney, we used a bilateral ischemia-reperfusion AKI mouse model, in which gallein attenuated renal dysfunction, tissue damage, fibrosis, inflammation, and ET system activation. Furthermore, in vitro studies showed a key role for ET receptor-Gβγ signaling in pathologic fibroblast activation. Overall, our data support a direct role for GPCR-Gβγ in AKI and suggest GPCR-Gβγ inhibition as a novel therapeutic approach for treating CRS2 and AKI., (Copyright © 2016 by the American Society of Nephrology.)

Background/aims: Renal tubulointerstitial fibrosis (TIF) is the common pathway of progressive chronic kidney disease. Inflammation has been widely accepted as the major driving force of TIF. Cystathionine β-synthase (CBS) is the first and rate-limiting enzyme in the transsulfuration pathway. CBS is considered to play protective role in liver and pulmonary fibrosis, but its role in TIF remains unknown. The purpose of this study was to investigate the potential role and mechanism of CBS in renal inflammation and TIF., Methods: Renal function, tubulointerstitium damage index score, extracellular matrix (ECM) deposition, and the expressions of collagen I, collagen III, fibronectin, CD3, CD68, IL-1β, TNF-α were measured in sham operation and unilateral ureteral obstruction (UUO) rats. Proteomics and gene array analysis were performed to screen differentially expressed molecules in the development of renal inflammation and TIF in UUO rats. The expression of CBS was detected in patients with obstructive nephropathy and UUO rats. We confirmed the expression of CBS using western blot and real-time PCR in HK-2 cells. Overexpression plasmid and siRNA were transfected specifically to study the possible function of CBS in HK-2 cells., Results: Abundant expression of CBS, localized in renal tubular epithelial cells, was revealed in human and rat renal tissue, which correlated negatively with the progression of fibrotic disease. Expression of CBS was dramatically decreased in the obstructed kidney from UUO rats as compared with the sham group (SHM). In addition, knocking down CBS exacerbated extracellular matrix (ECM) deposition, whereas CBS overexpression attenuated TGF-β1-induced ECM deposition in vitro. Inflammatory and chemotactic factors were also increased in CBS knockdown HK-2 cells stimulated by IL-1β., Conclusions: These findings establish CBS as a novel inhibitor in renal fibrosis and as a new therapeutic target in patients with chronic kidney disease., (© 2017 The Author(s). Published by S. Karger AG, Basel.)

The identification of the cellular origins of myofibroblasts has led to the discovery of novel pathways that potentially drive myofibroblast perpetuation in disease. Here, we further investigated the role of innate immune signaling pathways in this process. In mice, renal injury-induced activation of pericytes, which are myofibroblast precursors attached to endothelial cells, led to upregulated expression of TNF receptor superfamily member 12a, also known as fibroblast growth factor-inducible 14 (Fn14), by these cells. In live rat kidney slices, administration of the Fn14 ligand, TNF-related weak inducer of apoptosis (TWEAK), promoted pericyte-dependent vasoconstriction followed by pericyte detachment from capillaries. In vitro, administration of TWEAK activated and differentiated pericytes into cytokine-producing myofibroblasts, and further activated established myofibroblasts in a manner requiring canonical and noncanonical NF-κB signaling pathways. Deficiency of Fn14 protected mouse kidneys from fibrogenesis, inflammation, and associated vascular instability after in vivo injury, and was associated with loss of NF-κB signaling. In a genetic model of spontaneous CKD, therapeutic delivery of anti-TWEAK blocking antibodies attenuated disease progression, preserved organ function, and increased survival. These results identify the TWEAK-Fn14 signaling pathway as an important factor in myofibroblast perpetuation, fibrogenesis, and chronic disease progression., (Copyright © 2016 by the American Society of Nephrology.)

Bromodomain and extra-terminal (BET) protein inhibitors have been shown to effectively inhibit tumorgenesis and ameliorate pulmonary fibrosis by targeting bromodomain proteins that bind acetylated chromatin markers. However, their pharmacological effects in renal fibrosis remain unclear. In this study, we examined the effect of I-BET151, a selective and potent BET inhibitor, on renal fibroblast activation and renal fibrosis. In cultured renal interstitial fibroblasts, exposure of cells to I-BET151, or silencing of bromodoma in-containing protein 4 (Brd4), a key BET protein isoform, significantly reduced their activation as indicated by decreased expression of α-smooth muscle actin, collagen 1 and fibronectin. In a murine model of renal fibrosis induced by unilateral ureteral obstruction (UUO), administration of I-BET151 suppressed the deposition of extracellular matrix proteins, renal fibroblast activation and macrophage infiltration. Mechanistically, I-BET151 treatment abrogated UUO-induced phosphorylation of epidermal growth factor receptor and platelet growth factor receptor-β. It also inhibited the activation of Smad-3, STAT3 and NF-κB pathways, as well as the expression of c-Myc and P53 transcription factors in the kidney. Moreover, BET inhibition resulted in the reduction of renal epithelial cells arrested at the G2/M phase of cell cycle after UUO injury. Finally, injury to the kidney up-regulated Brd4, and I-BET151 treatment abrogated its expression. Brd4 was also highly expressed in human fibrotic kidneys. These data indicate that BET proteins are implicated in the regulation of signaling pathways and transcription factors associated with renal fibrogenesis, and suggest that pharmacological inhibition of BET proteins could be a potential treatment for renal fibrosis.

Like many organs, the kidney stiffens after injury, a process that is increasingly recognized as an important driver of fibrogenesis. Yes-associated protein (YAP) and transcriptional coactivator with PDZ-binding motif (TAZ) are related mechanosensory proteins that bind to Smad transcription factors, the canonical mediators of profibrotic TGF- β responses. Here, we investigated the role of YAP/TAZ in the matrix stiffness dependence of fibroblast responses to TGF- β In contrast to growth on a stiff surface, fibroblast growth on a soft matrix led to YAP/TAZ sequestration in the cytosol and impaired TGF- β -induced Smad2/3 nuclear accumulation and transcriptional activity. YAP knockdown or treatment with verteporfin, a drug that was recently identified as a potent YAP inhibitor, elicited similar changes. Furthermore, verteporfin reduced YAP/TAZ levels and decreased the total cellular levels of Smad2/3 after TGF- β stimulation. Verteporfin treatment of mice subjected to unilateral ureteral obstruction similarly reduced YAP/TAZ levels and nuclear Smad accumulation in the kidney, and attenuated renal fibrosis. Our data suggest that organ stiffening cooperates with TGF- β to induce fibrosis in a YAP/TAZ- and Smad2/3-dependent manner. Interference with this YAP/TAZ and TGF- β /Smad crosstalk likely underlies the antifibrotic activity of verteporfin. Finally, through repurposing of a clinically used drug, we illustrate the therapeutic potential of a novel mechanointerference strategy that blocks TGF- β signaling and renal fibrogenesis., (Copyright © 2016 by the American Society of Nephrology.)

Kidney fibrosis is a common histological manifestation of functional decline in the kidney. Fibrosis is a reactive process that develops in response to excessive epithelial injury and inflammation, leading to myofibroblast activation and an accumulation of extracellular matrix. Here, we describe how three key developmental signalling pathways - Notch, Wnt and Hedgehog (Hh) - are reactivated in response to kidney injury and contribute to the fibrotic response. Although transient activation of these pathways is needed for repair of injured tissue, their sustained activation is thought to promote fibrosis. Excessive Wnt and Notch expression prohibit epithelial differentiation, whereas increased Wnt and Hh expression induce fibroblast proliferation and myofibroblastic transdifferentiation. Notch, Wnt and Hh are fundamentally different signalling pathways, but their choreographed activation seems to be just as important for fibrosis as it is for embryonic kidney development. Decreasing the activity of Notch, Wnt or Hh signalling could potentially provide a new therapeutic strategy to ameliorate the development of fibrosis in chronic kidney disease.

Transforming growth factor-β (TGF-β) is the primary factor that drives fibrosis in most, if not all, forms of chronic kidney disease (CKD). Inhibition of the TGF-β isoform, TGF-β1, or its downstream signalling pathways substantially limits renal fibrosis in a wide range of disease models whereas overexpression of TGF-β1 induces renal fibrosis. TGF-β1 can induce renal fibrosis via activation of both canonical (Smad-based) and non-canonical (non-Smad-based) signalling pathways, which result in activation of myofibroblasts, excessive production of extracellular matrix (ECM) and inhibition of ECM degradation. The role of Smad proteins in the regulation of fibrosis is complex, with competing profibrotic and antifibrotic actions (including in the regulation of mesenchymal transitioning), and with complex interplay between TGF-β/Smads and other signalling pathways. Studies over the past 5 years have identified additional mechanisms that regulate the action of TGF-β1/Smad signalling in fibrosis, including short and long noncoding RNA molecules and epigenetic modifications of DNA and histone proteins. Although direct targeting of TGF-β1 is unlikely to yield a viable antifibrotic therapy due to the involvement of TGF-β1 in other processes, greater understanding of the various pathways by which TGF-β1 controls fibrosis has identified alternative targets for the development of novel therapeutics to halt this most damaging process in CKD.

Background: Renal interstitial fibrosis is characterized by excessive accumulation of extracellular matrix, which leads to end-stage renal failure., Purpose: The aim of this study was to explore the effect of Elsholtzia ciliata (Thunb.) Hylander ethanol extract (ECE) on renal interstitial fibrosis induced by unilateral ureteral obstruction (UUO)., Study Design: After quantitative analysis of ECE using the high performance liquid chromatography-photodiode array (HPLC-PDA) method, an in vitro study was performed to assess the anti-inflammatory and anti-fibrotic effects of ECE, using lipopolysaccharide (LPS) and transforming growth factor-ß (TGF-ß), respectively., Methods: For in vivo study, all male Sprague Dawley (SD) rats (n=10/group), except for those in the control group, underwent UUO. The rats were orally treated with water (control), captopril (positive control, 200 mg/kg), and ECE (300 and 500 mg/kg) for 14 days., Results: In ECE, luteolin and rosmarinic acid were relatively abundant among the other flavonoids and phenolic acids. ECE treatment ameliorated LPS-induced overexpression of nuclear factor-κB, tumor necrosis factor (TNF-α), and interleukin-6 and improved oxidative stress in RAW 264.7 cells. Furthermore, ECE treatment suppressed TGF-ß-induced α-smooth muscle actin and matrix metalloproteinase 9 expression in human renal mesangial cells. In the UUO model, 14 consecutive days of ECE treatment improved UUO-induced renal damage and attenuated histopathological alterations and interstitial fibrosis. Moreover, the renal expression of TNF-α, TGF-ß, and Smad 3 were inhibited by ECE treatment., Conclusion: Taken together, the effects of ECE may be mediated by blocking the activation of TGF-ß and inflammatory cytokines, leading subsequently to degradation of the ECM accumulation pathway. Based on these findings, ECE might serve as an improved treatment strategy for renal fibrotic disease., (Copyright © 2016 Elsevier GmbH. All rights reserved.)

Purpose: Kidney fibrosis is the most common final stage of progressive renal disease. Bone morphogenetic protein-7 (BMP-7) has been shown to be important in both preservation of kidney function and resistance to injury. Recently, it has been realized that uterine sensitization-associated gene-1 (USAG-1) functions as a kidney-specific BMP antagonist. Because of the reported anti-fibrotic effects of artesunate (Art), this study was designed to investigate the effects of Art on renal fibrosis in unilateral ureteral obstruction (UUO) rats and to explore the underlying mechanisms., Methods: Thirty male Sprague-Dawley rats were randomly divided into five groups: Sham group, UUO group, low-dose Art-treated (Art-L), middle-dose Art-treated (Art-M), and high-dose Art-treated (Art-H) groups. The UUO rat model was established by ligating the left ureter. Fourteen days later, interstitial collagen deposition, expression of USAG-1, BMP-7, E-cadherin, α-smooth muscle actin (α-SMA), fibronectin (FN), collagen I, as well as the inflammatory infiltration levels in the kidneys were assessed., Results: Art treatment significantly attenuated the deposition of interstitial collagens in the UUO rats' kidneys and exhibited the ability to improve renal function, followed by the up-regulated expression of BMP-7 and E-cadherin and the down-regulated expression of USAG-1 and α-SMA. In addition, increased macrophages infiltration in the kidneys of the UUO rats were also attenuated by the administration of Art., Conclusions: These results indicate that Art is able to improve the renal function decline and renal fibrosis induced by UUO, which may be associated with the up-regulation of BMP-7 and down-regulation of USAG-1. Accordingly, Art may become a potential preventive or therapeutic agent for chronic kidney diseases.