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Early-stage detection of chronic kidney diseases (CKD) is important to treatment that may slow and occasionally halt CKD progression. CKD of diverse etiologies share similar histologic patterns of glomerulosclerosis, tubular atrophy, and interstitial fibrosis. Macro-vascular disease and micro-vascular disease promote tissue ischemia, contributing to injury. Tissue ischemia promotes hypoxia, and this in turn activates the hypoxia-inducible transcription factors (HIFs). HIF-1α and HIF-2α, share a dimer partner, HIF-1β, with the aryl hydrocarbon receptor (AHR) and are each activated in CKD and associated with kidney cellular nicotinamide adenine dinucleotide (NAD) depletion. The Preiss-Handler, salvage, and de novo pathways regulate NAD biosynthesis and gap-junctions regulate NAD cellular retention. In the Preiss-Handler pathway, niacin forms NAD. Niacin also exhibits crosstalk with HIF and AHR cell signals in the regulation of insulin sensitivity, which is a complication in CKD. Dysregulated enzyme activity in the NAD de novo pathway increases the levels of circulating tryptophan metabolites that activate AHR, resulting in poly-ADP ribose polymerase activation, thrombosis, endothelial dysfunction, and immunosuppression. Therapeutically, metabolites from the NAD salvage pathway increase NAD production and subsequent sirtuin deacetylase activity, resulting in reduced activation of retinoic acid-inducible gene I, p53, NF-κB and SMAD2 but increased activation of FOXO1, PGC-1α, and DNA methyltransferase-1. These post-translational responses may also be initiated through non-coding RNAs (ncRNAs), which are additionally altered in CKD. Nanoparticles traverse biological systems and can penetrate almost all tissues as disease biomarkers and drug delivery carriers. Targeted delivery of non-coding RNAs or NAD metabolites with nanoparticles may enable the development of more effective diagnostics and therapies to treat CKD. [ABSTRACT FROM AUTHOR]

Genetic coding variants in APOL1, which encodes apolipoprotein L1 (APOL1), were identified in 2010 and are relatively common among individuals of sub-Saharan African ancestry. Approximately 13% of African Americans carry two APOL1 risk alleles. These variants, termed G1 and G2, are a frequent cause of kidney disease - termed APOL1 nephropathy - that typically manifests as focal segmental glomerulosclerosis and the clinical syndrome of hypertension and arterionephrosclerosis. Cell culture studies suggest that APOL1 variants cause cell dysfunction through several processes, including alterations in cation channel activity, inflammasome activation, increased endoplasmic reticulum stress, activation of protein kinase R, mitochondrial dysfunction and disruption of APOL1 ubiquitinylation. Risk of APOL1 nephropathy is mostly confined to individuals with two APOL1 risk variants. However, only a minority of individuals with two APOL1 risk alleles develop kidney disease, suggesting the need for a 'second hit'. The best recognized factor responsible for this 'second hit' is a chronic viral infection, particularly HIV-1, resulting in interferon-mediated activation of the APOL1 promoter, although most individuals with APOL1 nephropathy do not have an obvious cofactor. Current therapies for APOL1 nephropathies are not adequate to halt progression of chronic kidney disease, and new targeted molecular therapies are in clinical trials. [ABSTRACT FROM AUTHOR]

Access to essential medical care can be compromised by social disruptions (such as riots and labour strikes), armed conflict and natural disasters, including extreme weather events. A successful response to such events requires forward planning, preparation and rehearsal with involvement of health-care systems, professionals, patients and their support networks. Following execution of the response, after-action evaluation is required to improve future responses. [ABSTRACT FROM AUTHOR]

The article explores the spectrum of kidney diseases associated with human immunodeficiency virus (HIV) infection. Topics include the evaluation of renal syndrome in patients with HIV, HIV-associated nephropathy which arise from complex interactions among the virus, host genotype, and host response, and HIV-associated immune-mediated kidney disease. Therapeutic approaches for the treatment of diverse renal manifestations of HIV infection are explored.

The role of urokinase-type plasminogen activator receptor (uPAR) in kidney physiology and pathology has attracted considerable attention. The protein uPAR has dual functions: as a key regulator of plasmin generation and a component of the innate immune system. In the current issue, Wei and colleagues describe a transgenic mouse expressing Plaur RNA in glomerular podocytes. The mice manifested podocyte injury, including c-Src phosphorylation, proteinuria, and focal segmental glomerulosclerosis (FSGS). Plaur-transgenic mice on a β3 integrin–deficient background were protected from podocyte injury. Renal biopsies from subjects with FSGS, but not those with other glomerular diseases, manifested increased c-Src phosphorylation in podocytes. These findings suggest a novel injury mechanism in FSGS, with possible implications for new treatment strategies. [ABSTRACT FROM AUTHOR]

The article discusses the chronic kidney diseases in the cohort of 598 middle-aged human immunodeficiency virus-infected (HIV+) individuals. It states that the principal renal findings in the HIV+ cohort as compared to the uninfected were increased rates of tubular dysfunction, albuminuria which is defined as urine albumin and reduced estimated glomerular filtration rate.

APOL1 nephropathy occurs in a minority of genetically at-risk individuals, suggesting that other factors, such as other genes or environmental factors, contribute. Divers and colleagues report that among individuals with two APOL1 risk alleles, those with JC viruria are less likely to manifest kidney disease compared with those lacking JC viruria. These data might suggest that JC virus infection confers protection against glomerular injury, perhaps by altering cell function or generating immunity against a related polyomavirus. [ABSTRACT FROM AUTHOR]

APOL1 nephropathy occurs in a minority of genetically at-risk individuals, suggesting that other factors, such as other genes or environmental factors, contribute. Divers and colleagues report that among individuals with two APOL1 risk alleles, those with JC viruria are less likely to manifest kidney disease compared with those lacking JC viruria. These data might suggest that JC virus infection confers protection against glomerular injury, perhaps by altering cell function or generating immunity against a related polyomavirus. [ABSTRACT FROM AUTHOR]

Background Collapsing glomerulopathy may occur in an idiopathic (primary) form and in association with a wide spectrum of infectious and inflammatory conditions and medications. The association of collapsing glomerulopathy with human immunodeficiency virus (HIV)-1 infection is well established; less certain is the association with other viral infections. Methods We searched PubMed for articles in all languages that addressed glomerulopathies associated with parvovirus B19, cytomegalovirus (CMV), Epstein-Barr virus (EBV), hepatitis C virus (HCV) and simian virus 40 (SV40). Results Case reports and small-case series link infection with these common viruses and glomerular injury. The evidence for a pathogenic role is generally stronger for glomerulonephritis than for collapsing glomerulopathy. Conclusions The evidence linking collapsing glomerulopathy with CMV is relatively strong but not yet conclusive, while the evidence for a pathogenic role for EBV and parvovirus B19 is weaker. [ABSTRACT FROM PUBLISHER]

Background: Retinoic acid is the bioactive derivative of vitamin A, which plays an indispensible role in kidney development by activating retinoic acid receptors. Although the location, concentration and roles of endogenous retinoic acid in postnatal kidneys are poorly defined, there is accumulating evidence linking post-natal vitamin A deficiency to impaired renal concentrating and acidifying capacity associated with increased susceptibility to urolithiasis, renal inflammation and scarring. The aim of this study is to examine the presence and the detailed localization of endogenous retinoic acid activity in neonatal, young and adult mouse kidneys, to establish a fundamental ground for further research into potential target genes, as well as physiological and pathophysiological roles of endogenous retinoic acid in the post-natal kidneys. Methodology/Principal Findings: RARE-hsp68-lacZ transgenic mice were employed as a reporter for endogenous retinoic acid activity that was determined by X-gal assay and immunostaining of the reporter gene product, β-galactosidase. Double immunostaining was performed for β-galactosidase and markers of kidney tubules to localize retinoic acid activity. Distinct pattern of retinoic acid activity was observed in kidneys, which is higher in neonatal and 1- to 3-week-old mice than that in 5- and 8-week-old mice. The activity was present specifically in the principal cells and the intercalated cells of the collecting duct system in all age groups, but was absent from the glomeruli, proximal tubules, thin limbs of Henle's loop and distal tubules. Conclusions/Significance: Endogenous retinoic acid activity exists in principal cells and intercalated cells of the mouse collecting duct system after birth and persists into adulthood. This observation provides novel insights into potential roles for endogenous retinoic acid beyond nephrogenesis and warrants further studies to investigate target genes and functions of endogenous retinoic acid in the kidney after birth, particularly in the collecting duct system. [ABSTRACT FROM AUTHOR]

Genetic variation in MYH9, encoding non-muscle heavy chain IIA, has been recognized for over a decade as the cause of an autosomal dominant syndrome characterized by macrothrombocytopenia, neutrophil inclusions, and glomerular pathology. More recently, genetic variation in the MYH9 region on chromosome 22 has been associated with chronic kidney disease in African-descent individuals. A better understanding of the disease mechanisms responsible for glomerular injury in autosomal dominant MYH9 syndromes will lead to fuller appreciation of the role of this gene in glomerular biology. [ABSTRACT FROM AUTHOR]

The podocytopathies, including minimal-change nephropathy, focal segmental glomerulosclerosis, collapsing glomerulopathy, and diffuse mesangial sclerosis, involve diverse types of injury to podocytes. These injuries can have genetic causes, or can be caused by viral infection, mechanical stress, medication or-probably-immunologic injury. Several lines of evidence-including the immunosuppressive effects of standard therapies-suggest a role for immunologic injury in some cases, but the precise pathologic mechanisms are far from clear. Despite this uncertainty, newly available biologic therapies that target immune cells and cytokines have been used to treat a number of patients with different podocytopathies. Of these therapies, the greatest experience has been gained with rituximab. The data on all such therapies remain too fragmentary to provide firm conclusions, but further clinical research with such agents might help to define pathogenetic pathways and could potentially contribute to new therapies. [ABSTRACT FROM AUTHOR]

The increased burden of chronic kidney and end-stage kidney diseases (ESKD) in populations of African ancestry has been largely unexplained. To identify genetic variants predisposing to idiopathic and HIV-1–associated focal segmental glomerulosclerosis (FSGS), we carried out an admixture-mapping linkage-disequilibrium genome scan on 190 African American individuals with FSGS and 222 controls. We identified a chromosome 22 region with a genome-wide logarithm of the odds (lod) score of 9.2 and a peak lod of 12.4 centered on MYH9, a functional candidate gene expressed in kidney podocytes. Multiple MYH9 SNPs and haplotypes were recessively associated with FSGS, most strongly a haplotype spanning exons 14 through 23 (OR = 5.0, 95% CI = 3.5–7.1; P = 4 × 10−23, n = 852). This association extended to hypertensive ESKD (OR = 2.2, 95% CI = 1.5–3.4; n = 433), but not type 2 diabetic ESKD (n = 476). Genetic variation at the MYH9 locus substantially explains the increased burden of FSGS and hypertensive ESKD among African Americans. [ABSTRACT FROM AUTHOR]

Parvovirus B19 is a common human pathogen, causing erythema infectiosum in children, hydrops fetalis in pregnant women, and transient aplastic crisis in patients with chronic hemolytic anemia. Immunosuppressed patients can fail to mount an effective immune response to B19, resulting in prolonged or persistent viremia. Renal transplant recipients can develop symptomatic B19 infections as a result of primary infection acquired via the usual respiratory route or via the transplanted organ, or because of reactivation of latent or persistent viral infection. The most common manifestations of B19 infection in immunosuppressed patients are pure red cell aplasia and other cytopenias. Thus, this diagnosis should be considered in transplant recipients with unexplained anemia and reticulocytopenia or pancytopenia. Collapsing glomerulopathy and thrombotic microangiopathy have been reported in association with B19 infection in renal transplant recipients, but a causal relationship has not been definitively established. Prompt diagnosis of B19 infection in the renal transplant recipient requires a high index of suspicion and careful selection of diagnostic tests, which include serologies and polymerase chain reaction. Most patients benefit from intravenous immunoglobulin therapy and/or alteration or reduction of immunosuppressive therapy. Conservative therapy might be sufficient in some cases. [ABSTRACT FROM AUTHOR]

The recent advances in understanding the pathophysiology of focal segmental glomerulosclerosis (FSGS) and molecular function of glomerular filtration barrier come directly from genetic linkage and positional cloning studies. The exact role and function of the newly discovered genes and proteins are being investigated by in vitro and in vivo mechanistic studies. Those genes and proteins interactions seem to change susceptibility to kidney disease progression. Better understanding of their exact role in the development of FSGS may influence future therapies and outcomes in this complex disease. [ABSTRACT FROM AUTHOR]

Fabry disease, the second most prevalent lysosomal storage disorder after Gaucher disease, is caused by mutations of the gene encoding the lysosomal hydrolase, α-galactosidase A. The enzymatic defect is inherited in an X-linked recessive fashion and leads to systemic glycosphingolipid deposition, resulting in profound dysfunction of neurological, renal, cardiac, and cerebrovascular systems. Although symptoms typically appear in childhood in hemizygous males and some heterozygous females, the diagnosis is often delayed or unrecognized, owing to variable presentations and low incidence. The initial phase begins in childhood or adolescence and is characterized by neuropathic pain, angiokeratomas, and ocular deposits. The later phase is distinguished by progressive cardiac, cerebral, and renal involvement, leading to multi-organ dysfunction and death. Recently published clinical trials have demonstrated the efficacy of enzyme replacement therapy in decreasing neuropathic pain and substrate deposition in target organs. Pediatricians have a key role to play in making the diagnosis, so that therapy can be initiated before irreversible tissue injury develops. Further research is required to determine optimal dosing protocols for treatment and to establish whether therapy can retard the progression of organ dysfunction, or even prevent these complications altogether. [ABSTRACT FROM AUTHOR]

HIV-associated nephropathy in African Americans. Human immunodeficiency virus-1 (HIV-1) infection is associated with several glomerular syndromes, the most prevalent of which is HIV-associated focal segmental glomerulosclerosis (FSGS). At present, HIV-associated FSGS may account for up to 30% of patients in the United States entering end-stage renal disease (ESRD) as a consequence of FSGS. The mechanisms responsible for HIV-associated FSGS are not well defined, but evidence has been presented in favor of direct infection of renal parenchymal cells and toxicity of HIV-1 accessory proteins. HIV-associated FSGS has a striking predilection for patients of African descent. This likely has a genetic basis, although the gene or genes responsible have not yet been identified. One approach is to examine candidate genes for polymorphisms that are associated with disease. Another approach uses a genome-wide scan, relying upon linkage disequilibrium between DNA markers and the disease gene, to identify the causal gene or genes. African Americans are an admixed population, with genetic contributions from African, European, and Native American populations. In admixed populations, linkage disequilibrium between disease genes and marker genes can be exploited to identify disease genes, using an approach termed mapping by admixture linkage disequilibrium (MALD). [ABSTRACT FROM AUTHOR]

The objective of the present study was to characterize the genitourinary syndromes that accompany indinavir-associated pyuria. Of 23 indinavir-treated patients with persistent pyuria, 4 had isolated interstitial nephritis, 10 had both interstitial nephritis and urothelial inflammation, 7 had isolated urothelial inflammation, and 2 had pyuria with nonspecific urinary tract inflammation. A total of 21 patients had multinucleated histiocytes identified by cytologic testing of urine specimens. Urine abnormalities resolved in all 20 patients who stopped receiving indinavir therapy. Pyuria continued in the 3 patients who continued receiving indinavir. Six patients had elevated serum creatinine levels, which returned to baseline levels when indinavir was discontinued. In conclusion, indinavir-associated pyuria was frequently associated with evidence of interstitial nephritis and/or urothelial inflammation, multinucleated histiocytes were commonly present in urine specimens, and cessation of indinavir therapy was associated with prompt resolution of urine abnormalities. [ABSTRACT FROM AUTHOR]

Reports on a study to evaluate the safety and efficacy of intravenous alpha-galactosidase A (alpha-gal A), a lysosomal enzyme, for Fabry disease. Causes of Fabry disease, a metabolic disorder which has no specific treatment; Methods; Results, including reduced severity of neuropathic pain in patients receiving alpha-gal A; Conclusions on the safety and efficacy of alpha-gal A.

Glomerulosclerosis and viral gene expression in HIV-transgenic mice: Role of nef. Background. Human immunodeficiency virus (HIV)-associated nephropathy is characterized by focal segmental glomerulosclerosis and microcystic tubular dilation. We have previously described a mouse transgenic for a Δgag-pol HIV-1 genome, which develops glomerulosclerosis, cutaneous papillomas, and cataracts. Methods. We developed mice transgenic for a Δgag-pol-nef HIV genome in order to investigate the role of the nef gene in these phenotypes. Results. One transgenic line, X5, expressed HIV mRNA in kidney and consistently manifested focal segmental glomerulosclerosis and tubular dilation by six weeks of age. Northern analysis indicated that renal transgene expression was higher in the Δgag-pol-nef mice compared with the Δgag-pol mice. In situ hybridization and immunostaining demonstrated HIV RNA and protein expression within the glomerular epithelial cells and tubular epithelial cells. These cell types showed histologic evidence of toxicity, including vacuolation and detachment from basement membrane, and exhibited increased rates of apoptosis. These data suggest that the renal disease seen in the Δgag-pol-nef transgenic mouse may be caused by the expression of HIV genes within renal epithelial cells, that this expression may induce cellular toxicity, including apoptosis, and that nef is not required for the induction of renal disease. We have previously described mice bearing the nef gene, which do not manifest renal disease. In further experiments, Δgag-pol-nef mice were bred with nef mice; these dual-transgenic mice developed renal disease that generally resembled that seen in Δgag-pol-nef mice, but with somewhat more severe glomerulosclerosis and less severe tubulointerstitial injury. Results. The results of these transgenic studies suggest that the role of nef is complex and may act both to reduce transgene expression and to potentiate... [ABSTRACT FROM AUTHOR]

Characterizes a source of superoxide anions in the kidney referred to as a renal NAD(P)H oxidase or renox. RNA hybridization's revelation that renox is highly expressed at the site of erythropoietin production in the renal cortex; Northern blot analysis and in situ hybridization; Cell culture and cell transfection.

Chronic rejection of mouse kidney allografts. Background. Chronic renal allograft rejection is the leading cause of late graft failure. However, its pathogenesis has not been defined. Methods. To explore the pathogenesis of chronic rejection, we studied a mouse model of kidney transplantation and examined the effects of altering the expression of donor major histocompatibility complex (MHC) antigens on the development of chronic rejection. Results. We found that long-surviving mouse kidney allografts develop pathological abnormalities that resemble chronic rejection in humans. Furthermore, the absence of MHC class I or class II antigens did not prevent the loss of graft function nor alter the pathological characteristics of chronic rejection. Expression of transforming growth factor-β (TGF-β), a pleiotropic cytokine suggested to play a role in chronic rejection, was markedly enhanced in control allografts compared with isografts. However, TGF-β up-regulation was significantly blunted in MHC-deficient grafts. Nonetheless, these differences in TGF-β expression did not affect the character of chronic rejection, including intrarenal accumulation of collagens. Conclusions. Reduced expression of either class I or II direct allorecognition pathways is insufficient to prevent the development of chronic rejection, despite a reduction in the levels of TGF-β expressed in the allograft. This suggests that the severity of chronic rejection is independent of the level of MHC disparity between donor and recipient and the level of TGF-β expression within the allograft. [ABSTRACT FROM AUTHOR]

Investigates the temporal and spatial distribution of osteogenic protein 1 (OP-1/bone morphogenetic protein 7) RNA during early embryonic kidney development and the role of OP-1 in metanephric differentiation in vitro. Failure to undergo mesenchymal condensation and epithelialization; Development pattern similar to that observed in the spinal cord.

Looks at the areas of application of transgenic animals in renal development and pathogenesis research. Includes role of various oncogenes, homeobox genes and growth factors in renal development; Pathogenesis of cystic renal diseases; Contribution of systemic and local expression of the renin-angiotensin system to blood pressure control.

Discusses the composition of urinary crystals and the frequency of asympomatic crystalluria as it relates to urinary tract symptoms in patients receiving indinavir. Background information on indinavir; Benefits of using this device; Study carried out in the using indinvir; Results from study; Methodology used in the study; Provision of statistical information.

The article focuses on the role of chronic kidney disease (CKD) biomarkers in predicting the mortality of HIV patients. It presents the study conducted by A. I Choi among HIV-infected participants who underwent a multivariable analysis using the inflammatory markers C-reactive protein (CRP) and fibrinogen. The author discusses the role of serum creatinine and cystatin C levels in calculating the estimated glomerular filtration rate (eGFR) and in predicting the 5-year mortality of HIV patients.

Poly-(ADP-ribose) polymerases (PARPs) are a protein family that make ADP-ribose modifications on target genes and proteins. PARP family members contribute to the pathogenesis of chronic inflammatory diseases, including atherosclerosis, in which monocytes/macrophages play important roles. PARP inhibition is protective against atherosclerosis. However, the mechanisms by which PARP inhibition exerts this beneficial effect are not well understood. Here we show that in THP-1 monocytes, inhibition of PARP by olaparib attenuated oxidized low-density lipoprotein (oxLDL)-induced protein expressions of nucleotide-binding oligomerization domain, leucine-rich repeat and pyrin domain-containing-3 (NLRP3) inflammasome components: NLRP3, apoptosis-associated speck-like protein containing a caspase activation and recruitment domain (ASC), and caspase-1. Consistent with this effect, olaparib decreased oxLDL-enhanced interleukin (IL)-1β and IL-18 protein expression. Olaparib also decreased the oxLDL-mediated increase in mitochondrial reactive oxygen species. Similar to the effects of the NLRP3 inhibitor, MCC950, olaparib attenuated oxLDL-induced adhesion of monocytes to cultured human umbilical vein endothelial cells and reduced foam cell formation. Furthermore, olaparib attenuated the oxLDL-mediated activation of nuclear factor (NF)-κB through the oxLDL-mediated increase in IκBα phosphorylation and assembly of NF-κB subunits, demonstrated by co-immunoprecipitation of IκBα with RelA/p50 and RelB/p52 subunits. Moreover, PARP inhibition decreased oxLDL-mediated protein expression of a NF-κB target gene, VCAM1, encoding vascular cell adhesion molecule-1. This finding indicates an important role for NF-κB activity in PARP-mediated activation of the NLRP3 inflammasome. Thus, PARP inhibition by olaparib attenuates NF-κB and NLRP3 inflammasome activities, lessening monocyte cell adhesion and macrophage foam cell formation. These inhibitory effects of olaparib on NLRP3 activity potentially protect against atherosclerosis. [ABSTRACT FROM AUTHOR]

While progressive podocytopenia is a characteristic feature of chronic glomerular disease, the visceral epithelial niche can be replenished from the parietal epithelium. Two new reports demonstrate this process in genetically engineered mice, using fate mapping, and in human renal biopsies manifesting segmental glomerulosclerosis in diverse settings, using cellular and extracellular matrix markers. [ABSTRACT FROM AUTHOR]

The year 2012 brought a continued harvest of new findings of relevance to glomerular biology and disease. Progress in glomerular disease has continued, although our understanding of disease processes continues to extend much further than our ability to intervene effectively. [ABSTRACT FROM AUTHOR]

The author discusses studies related to glomerular biology and disease that were released in 2012. He describes one study that investigated levels of anti-PLA2R antibodies in patients with idiopathic membranous nephropathy and nephrotic-range proteinuria. He mentions another study that tested novel treatment approaches in type 2 diabetic nephropathy. He believes that a gap still exists between people's understanding of disease mechanisms and their ability to devise effective therapy.

Editorial. Comments on the role of bone morphogenic protein-7 (BMP-7) in normal renal development. Expression of BMP-7 by uteric bud and nephrogenic mesenchyme and the collecting tubules; Promotion of nephrogenesis by isolated metanephric mesenchyme; Enumeration of the other functions of BMP-7.

Editorial. Discusses the identification of bone matrix protein receptors for normal kidney development. Expansion of mesenchymal cell population; Differentiation of putative epithelial stem cell; Promotion of bone mineral homeostasis.

Transforming growth factor (TGF)-β1 contributes to podocyte injury in various glomerular diseases, including diabetic kidney disease, probably at least in part by attenuating the expression of Wilms' tumor 1 (WT1). However, the precise mechanisms remain to be defined. We performed miRNA microarray analysis in a human podocyte cell line cultured with TGF-β1 to examine the roles of miRNAs in podocyte damage. The microarray analysis identified miR-143-3p as the miRNA with the greatest increase following exposure to TGF-β1. Quantitative RT-PCR confirmed a significant increase in the miR-143-3p/145-5p cluster in TGF-β1-supplemented cultured podocytes and demonstrated upregulation of miR-143-3p in the glomeruli of mice with type 2 diabetes. Ectopic expression of miR-143-3p and miR-145-5p suppressed WT1 expression in cultured podocytes. Furthermore, inhibition of Smad or mammalian target of rapamycin signaling each partially reversed the TGF-β1-induced increase in miR-143-3p/145-5p and decrease in WT1. In conclusion, TGF-β1 induces expression of miR-143-3p/145-5p in part through Smad and mammalian target of rapamycin pathways, and miR-143-3p/145-5p reduces expression of WT1 in cultured human podocytes. miR-143-3p/145-5p may contribute to TGF-β1-induced podocyte injury. [ABSTRACT FROM AUTHOR]

Editorial. Comments on the ability of hepatocyte growth factor (HGF) to stimulate mitogenesis of hepatocytes. Effects of HGF on cell morphology; Role of HGF in branching morphogenesis in development; Implication of HGF in renal tubular epithelial proliferation in vivo.

Nonalcoholic steatohepatitis (NASH) is the most common chronic liver disease in the US, partly due to the increasing incidence of metabolic syndrome, obesity, and type 2 diabetes. The roles of bile acids and their receptors, such as the nuclear receptor farnesoid X receptor (FXR) and the G protein-coupled receptor TGR5, on the development of NASH are not fully clear. C57BL/6J male mice fed a Western diet (WD) develop characteristics of NASH, allowing determination of the effects of FXR and TGR5 agonists on this disease. Here we show that the FXR-TGR5 dual agonist INT-767 prevents progression of WD-induced hepatic steatosis, inflammation, and fibrosis, as determined by histological and biochemical assays and novel label-free microscopy imaging techniques, including third harmonic generation, second harmonic generation, and fluorescence lifetime imaging microscopy. Furthermore, we show INT-767 decreases liver fatty acid synthesis and fatty acid and cholesterol uptake, as well as liver inflammation. INT-767 markedly changed bile acid composition in the liver and intestine, leading to notable decreases in the hydrophobicity index of bile acids, known to limit cholesterol and lipid absorption. In addition, INT-767 upregulated expression of liver p-AMPK, SIRT1, PGC-1α, and SIRT3, which are master regulators of mitochondrial function. Finally, we found INT-767 treatment reduced WD-induced dysbiosis of gut microbiota. Interestingly, the effects of INT-767 in attenuating NASH were absent in FXR-null mice, but still present in TGR5-null mice. Our findings support treatment and prevention protocols with the dual FXR-TGR5 agonist INT-767 arrest progression of WD-induced NASH in mice mediated by FXRdependent, TGR5-independent mechanisms. [ABSTRACT FROM AUTHOR]

The article describes the case of a 30-year-old man who experienced neuropathic pain that affected his hands and feet. Angiokeratomas were found in the groin and on the back. Based on the examination, there was tortuous retinal arterioles. The detection of reduced galactosidase A activity in peripheral leukocytes confirmed the diagnosis of Fabry's disease. Carbamezapine was given for the neuropathic pain. The patient's symptoms have improved, but his renal function has continued to deteriorate, with a serum creatinine concentration of 2.2 mg per deciliter.

HIV-associated nephropathy in African Americans. Human immunodeficiency virus-1 (HIV-1) infection is associated with several glomerular syndromes, the most prevalent of which is HIV-associated focal segmental glomerulosclerosis (FSGS). At present, HIV-associated FSGS may account for up to 30% of patients in the United States entering end-stage renal disease (ESRD) as a consequence of FSGS. The mechanisms responsible for HIV-associated FSGS are not well defined, but evidence has been presented in favor of direct infection of renal parenchymal cells and toxicity of HIV-1 accessory proteins. HIV-associated FSGS has a striking predilection for patients of African descent. This likely has a genetic basis, although the gene or genes responsible have not yet been identified. One approach is to examine candidate genes for polymorphisms that are associated with disease. Another approach uses a genome-wide scan, relying upon linkage disequilibrium between DNA markers and the disease gene, to identify the causal gene or genes. African Americans are an admixed population, with genetic contributions from African, European, and Native American populations. In admixed populations, linkage disequilibrium between disease genes and marker genes can be exploited to identify disease genes, using an approach termed mapping by admixture linkage disequilibrium (MALD). [ABSTRACT FROM AUTHOR]

Background: Genetic variants in apolipoprotein L1 (APOL1), a protein that protects humans from infection with African trypanosomes, explain a substantial proportion of the excess risk of chronic kidney disease affecting individuals with sub-Saharan ancestry. The mechanisms by which risk variants damage kidney cells remain incompletely understood. In preclinical models, APOL1 expressed in podocytes can lead to significant kidney injury. In humans, studies in kidney transplant suggest that the effects of APOL1 variants are predominantly driven by donor genotype. Less attention has been paid to a possible role for circulating APOL1 in kidney injury. Methods: Using liquid chromatography-tandem mass spectrometry, the concentrations of APOL1 were measured in plasma and urine from participants in the Seattle Kidney Study. Asymmetric flow field-flow fractionation was used to evaluate the size of APOL1-containing lipoprotein particles in plasma. Transgenic mice that express wild-type or risk variant APOL1 from an albumin promoter were treated to cause kidney injury and evaluated for renal disease and pathology. Results: In human participants, urine concentrations of APOL1 were correlated with plasma concentrations and reduced kidney function. Risk variant APOL1 was enriched in larger particles. In mice, circulating risk variant APOL1-G1 promoted kidney damage and reduced podocyte density without renal expression of APOL1. Conclusions: These results suggest that plasma APOL1 is dynamic and contributes to the progression of kidney disease in humans, which may have implications for treatment of APOL1-associated kidney disease and for kidney transplantation. [ABSTRACT FROM AUTHOR]

HIV-associated nephropathy (HIVAN) impairs functions of both glomeruli and tubules. Attention has been previously focused on the HIVAN glomerulopathy. Tubular injury has drawn increased attention because sodium wasting is common in hospitalized HIV/AIDS patients. We used viral protein R (Vpr)-transgenic mice to investigate the mechanisms whereby Vpr contributes to urinary sodium wasting. In phosphoenolpyruvate carboxykinase promoter-driven Vpr-transgenic mice, in situ hybridization showed that Vpr mRNA was expressed in all nephron segments, including the distal convoluted tubule. Vpr-transgenic mice, compared with wild-type littermates, markedly increased urinary sodium excretion, despite similar plasma renin activity and aldosterone levels. Kidneys from Vpr-transgenic mice also markedly reduced protein abundance of the Na+-Cl- cotransporter (NCC), while mineralocorticoid receptor (MR) protein expression level was unchanged. In African green monkey kidney cells, Vpr abrogated the aldosterone-mediated stimulation of MR transcriptional activity. Gene expression of Slc12a3 (NCC) in Vpr-transgenic mice was significantly lower compared with wild-type mice, assessed by both qRT-PCR and RNAScope in situ hybridization analysis. Chromatin immunoprecipitation assays identified multiple MR response elements (MRE), located from 5 kb upstream of the transcription start site and extending to the third exon of the SLC12A3 gene. Mutation of MRE and SP1 sites in the SLC12A3 promoter region abrogated the transcriptional responses to aldosterone and Vpr, indicating that functional MRE and SP1 are required for the SLC12A3 gene suppression in response to Vpr. Thus, Vpr attenuates MR transcriptional activity and inhibits Slc12a3 transcription in the distal convoluted tubule and contributes to salt wasting in Vpr-transgenic mice. [ABSTRACT FROM AUTHOR]

Background: Microalbuminuria is an independent risk factor for cardiovascular and kidney disease and a predictor of end organ damage, both in the general population and in persons with HIV (PWH). Microalbuminuria is also an important risk factor for mortality in PWH treated with antiretroviral therapy (ART). In the ongoing Renal Risk Reduction (R3) study in Nigeria, we identified a high prevalence of microalbuminuria confirmed by two measurements 4-8 weeks apart in ART-experienced, virologically suppressed PWH. Although Stage 1 or 2 hypertension and exposure to potentially nephrotoxic antiretroviral medications were common in R3 participants, other traditional risk factors for albuminuria and kidney disease, including diabetes, APOL1 high-risk genotype, and smoking were rare. Co-infection with endemic pathogens may also be significant contributors to albuminuria, but co-infections were not evaluated in the R3 study population.Methods: In Aim 1, we will cross-sectionally compare the prevalence of albuminuria and established kidney disease risk factors in a cohort of PWH to age- and sex-matched HIV-negative adults presenting for routine care at the Aminu Kano Teaching Hospital in Kano, Nigeria. We will leverage stored specimens from 2500 R3 participants and enroll an additional 500 PLWH recently initiated on ART (≤ 24 months) and 750 age- and sex-matched HIV-negative adults to determine the contribution of HIV, hypertension, and other comorbid medical conditions to prevalent albuminuria. In Aim 2, we will follow a cohort of 1000 HIV-positive, ART-treated and 500 HIV-negative normoalbuminuric adults for 30 months to evaluate the incidence and predictors of albuminuria.Discussion: The findings from this study will support the development of interventions to prevent or address microalbuminuria in PWH to reduce kidney and cardiovascular morbidity and mortality. Such interventions might include more intensive monitoring and treatment of traditional risk factors, the provision of renin-angiotensin aldosterone system or sodium-glucose cotransporter-2 inhibitors, consideration of changes in ART regimen, and screening and treatment for relevant co-infections. [ABSTRACT FROM AUTHOR]

Objective: Current guidelines for gout recommend a treat-to-target approach with serum uric acid (SUA). However, there is little evidence for the dose-dependent effects of urate-lowering therapy (ULT). Herein, we analyzed the reported SUA-lowering effect and SUA target achievement differences for various doses of xanthine oxidase inhibitors. Methods: Approved ULT drugs were selected from the FDA Drug Database. We included prospective randomized controlled trials of ULT drugs from ClinicalTrials.gov, articles published in the journal "Drugs", and Embase, a literature database. A meta-analysis was performed to determine the ability of different ULT drugs and doses to lower and maintain a target SUA < 6 mg/dL. Results: We identified 35 trials including 8172 patients with a baseline SUA of 8.92 mg/dL. The allopurinol, febuxostat, and topiroxostat showed dose-proportional SUA-lowering responses. Compared with allopurinol 300 mg daily, febuxostat 80 mg daily and 120 mg daily more effectively maintained SUA < 6 mg/dL. Conclusion: Allopurinol, febuxostat, and topiroxostat showed dose-proportional ability to lower and achieve a target SUA < 6 mg/dL. Significance and Innovations. We showed dose-dependent SUA lowering effects of allopurinol, febuxostat, and topiroxostat. Febuxostat is effective at ULT compared to allopurinol and could be potentially offered as an alternative agent when patients (1) have CKD, (2) have the human leukocyte antigen HLA-B*5801 allele, and (3) become refractory to allopurinol. Gradual allopurinol dose increase with a lower starting dose is needed in CKD. [ABSTRACT FROM AUTHOR]

In the past 15 years, major advances have been made in understanding the role of lipids in podocyte biology. First, susceptibility to focal segmental glomerulosclerosis (FSGS) and glomerular disease is associated with an APOL1 sequence variant, is expressed in podocytes and encodes apolipoprotein LI, an important component of HDL. Second, acid sphingomyelinase-like phosphodiesterase 3b encoded by SMPDL3b has a role in the conversion of sphingomyelin to ceramide and its levels are reduced in renal biopsy samples from patients with recurrent FSGS. Furthermore, decreased SMPDL3b expression is associated with increased susceptibility of podocytes to injury after exposure to sera from these patients. Third, in many individuals with membranous nephropathy, autoantibodies against the phospholipase A2 (PLA2) receptor, which is expressed in podocytes, have been identified. Whether these autoantibodies affect the activity of PLA2, which liberates arachidonic acid from glycerophospholipids and modulates podocyte function, is unknown. Fourth, clinical and experimental evidence support a role for ATP-binding cassette sub-family A member 1-dependent cholesterol efflux, free fatty acids and glycerophospolipids in the pathogenesis of diabetic kidney disease. An improved understanding of lipid biology in podocytes might provide insights to develop therapeutic targets for primary and secondary glomerulopathies. [ABSTRACT FROM AUTHOR]

The renal glomerulus forms a selective filtration barrier that allows the passage of water, ions, and small solutes into the urinary space while restricting the passage of cells and macromolecules. The three layers of the glomerular filtration barrier include the vascular endothelium, glomerular basement membrane (GBM), and podocyte epithelium. Podocytes are capable of internalizing albumin and are hypothesized to clear proteins that traverse the GBM. The present study followed the fate of FITC-labeled albumin to establish the mechanisms of albumin endocytosis and processing by podocytes. Confocal imaging and total internal reflection fluorescence microscopy of immortalized human podocytes showed FITC-albumin endocytosis occurred preferentially across the basal membrane. Inhibition of clathrin-mediated endocytosis and caveolae-mediated endocytosis demonstrated that the majority of FITC-albumin entered podocytes through caveolae. Once internalized, FITC-albumin colocalized with EEA1 and LAMP1, endocytic markers, and with the neonatal Fc receptor, a marker for transcytosis. After preloading podocytes with FITC-albumin, the majority of loaded FITC-albumin was lost over the subsequent 60 min of incubation. A portion of the loss of albumin occurred via lysosomal degradation as pretreatment with leupeptin, a lysosomal protease inhibitor, partially inhibited the loss of FITC-albumin. Consistent with transcytosis of albumin, preloaded podocytes also progressively released FITC-albumin into the extracellular media. These studies confirm the ability of podocytes to endocytose albumin and provide mechanistic insight into cellular mechanisms and fates of albumin handling in podocytes. [ABSTRACT FROM AUTHOR]

Background. Wilms' tumor suppressor gene (WT1) is essential for normal podocyte function, and transforming growth factor (TGF)-beta contributes to focal segmental glomerulosclerosis (FSGS). We aimed to address whether TGF-beta affects WT1 expression in podocytes.Methods. A human podocyte cell line treated with TGF-beta1 and kidneys in Alb/TGF-beta1-transgenic mice were analyzed for WT1 expression.Results. In cultured podocytes, TGF-beta1 reduced WT1 protein expression determined by western blotting beginning at 8 h and decreased WT1 messenger RNA (mRNA) expression measured by quantitative reverse transcription–polymerase chain reaction beginning at 3 h. Knockdown of Smad4 by small hairpin (sh) RNA partially rescued the TGF-beta1-induced reduction of both WT1 protein and mRNA expressions in the cultured podocytes. TGF-beta1 did not alter luciferase activity of the reporter construct for a human WT1 promoter but reduced that for a human WT1 5′ enhancer construct, suggesting that TGF-beta1 may regulate WT1 expression by altering the 5′ enhancer activity. In the transgenic mice, WT1 protein expression in podocytes was decreased at 1 and 3 weeks of age, while glomeruloclerosis developed after 3 weeks.Conclusion. TGF-beta1 reduces WT1 expression in cultured human podocytes and podocytes in mice before overt glomerulosclerosis begins. The effects are at least partially Smad4 dependent. Our findings identify a novel pathway linking TGF-beta1 to podocyte injury and FSGS. The WT1 reduction may be a useful marker for early podocyte injury. [ABSTRACT FROM PUBLISHER]

Studies have shown that certain cells of the glomerular tuft begin to express proteins considered unique to other cell types upon injury. Little is known about the response of parietal epithelial cells (PEC) to injury. To determine whether PECs change their phenotype upon injury to also express proteins traditionally considered podocyte specific, the following four models of glomerular disease were studied: the transforming growth factor (TGF)-β1 transgenic mouse model of global glomerulosclerosis, the adriamycin model of focal segmental glomerulosclerosis (FSGS), the anti-glomerular basement membrane (GBM) model of crescentic glomerulonephritis, and the passive Heymann nephritis model of membranous nephropathy. Double immunostaining was performed with antibodies to podocyte-specific proteins (synaptopodin and Wilms' tumor 1) and antibodies to PEC specific proteins (paired box gene 8 and claudin-1). No double staining was detected in normal mice. In contrast, the results showed a statistical increase in the number of cells attached to Bowman basement membrane that were double-positive for both podocyte/PEC proteins in TGF-β;1 transgenic, anti-GBM, and membranous animals. Double-positive cells for both podocyte and PEC proteins were also statistically increased in the glomerular tuft in TGF-β1 transgenic, anti-GBM, and FSGS mice. These results are consistent with glomerular cells coexpressing podocyte and PEC proteins in experimental glomerular disease, but not under normal circumstances. [ABSTRACT FROM AUTHOR]

Context.—Etiologic factors and pathways leading to altered podocyte phenotype are clearly numerous and involve the activity of different cellular function. Objective.—To focus on recent discoveries in podocyte biology and genetics and their relevance to these human glomerular diseases, named podocytopathies. Data Sources.—Genetic mutations in genes encoding for proteins in the nucleus, slit diaphragm, podocyte cytoplasm, and cell membrane are responsible for podocyte phenotype and functional abnormalities. Podocyte injury may also derive from secondary stimuli, such as mechanical stress, infections, or use of certain medications. Podocytes can respond to injury in a limited number of ways, which include (1) effacement, (2) apoptosis, (3) arrest of development, and (4) dedifferentiation. Each of these pathways results in a specific glomerular morphology: minimal change nephropathy, focal segmental glomerulosclerosis, diffuse mesangial sclerosis, and collapsing glomerulopathy. Conclusions.—Based on current knowledge of podocyte biology, we organized etiologic factors and morphologic features in a taxonomy of podocytopathies, which provides a novel approach to the classification of these diseases. Current and experimental therapeutic approaches are also discussed. [ABSTRACT FROM AUTHOR]

Coding variants in apolipoprotein L1 (APOL1), termed G1 and G2, can explain most excess kidney disease risk in African Americans; however, the molecular pathways of APOL1-induced kidney dysfunction remain poorly understood. Here, we report that expression of G2 APOL1 in the podocytes of Nphs1rtTA/TRE-G2APOL1 (G2APOL1) mice leads to early activation of the cytosolic nucleotide sensor, stimulator of interferon genes (STING), and the NLR family pyrin domain–containing 3 (NLRP3) inflammasome. STING and NLRP3 expression was increased in podocytes from patients with high-risk APOL1 genotypes, and expression of APOL1 correlated with caspase-1 and gasdermin D (GSDMD) levels. To demonstrate the role of NLRP3 and STING in APOL1-associated kidney disease, we generated transgenic mice with the G2 APOL1 risk variant and genetic deletion of Nlrp3 (G2APOL1/Nlrp3 KO), Gsdmd (G2APOL1/Gsdmd KO), and STING (G2APOL1/STING KO). Knockout mice displayed marked reduction in albuminuria, azotemia, and kidney fibrosis compared with G2APOL1 mice. To evaluate the therapeutic potential of targeting NLRP3, GSDMD, and STING, we treated mice with MCC950, disulfiram, and C176, potent and selective inhibitors of NLRP3, GSDMD, and STING, respectively. G2APOL1 mice treated with MCC950, disulfiram, and C176 showed lower albuminuria and improved kidney function even when inhibitor treatment was initiated after the development of albuminuria. [ABSTRACT FROM AUTHOR]

HIV infection is associated with several renal syndromes, including acute renal failure. Chronic renal failure directly linked to HIV infection includes thrombotic microangiopathic renal diseases, immune-mediated glomerulonephritides, and HIV-associated nephropathy. A renal biopsy may be necessary for diagnosis. The development of HIV-associated nephropathy has been definitively linked to renal cellular infection, but the disease affects only a minority of patients, typically men of African descent. Therefore, factors determining disease expression in infected patients must now be emphasized. The pathogenic mechanisms involved in HIV-associated renal disease remain obscure. Genetic factors, as well as renal cellular responses, mediated by HIV proteins (including an immune-activated microenvironment) capable of presenting antigen in susceptible hosts probably explain most cases. HIV-associated nephropathy has a characteristic pathologic phenotype, including glomerular, tubular, and interstitial changes, and ultrastructural findings. Infection of the glomerular epithelial cell, or podocyte, and consequent structural and biochemical changes may be pivotal in pathogenesis. The HIV-1 transgenic mouse is an important model for understanding disease pathogenesis, particularly the role of HIV proteins in mediating renal tissue injury. Rigorously controlled randomized trials have not evaluated treatment, but corticosteroids and angiotensin-converting enzyme inhibitors have been used. Highly active antiretroviral therapy seems to have decreased the incidence of end-stage renal disease related to HIV infection and, in case reports, to have improved renal functional and pathologic outcomes of HIV-associated nephropathy. Outcomes in patients undergoing hemodialysis and peritoneal dialysis have improved, and current research focuses on renal transplantation for treatment of HIV-infected patients. [ABSTRACT FROM AUTHOR]

Apolipoprotein L1 (APOL1), an innate immune factor against African trypanosoma brucei, inhibits HIV-1 in vitro. The impact of APOL1 G1-G2 variants on HIV-1-associated opportunistic infections (OIs) is unknown. Here, we report findings from a metaanalysis of four HIV/AIDS prospective cohorts (ALIVE, LSOCA, MACS, and WIHS) including 2066 African American participants. Using a global test combining all four cohorts, carriage of two APOL1 variant alleles is associated with a 50% reduction in odds of OI (combined OR 0.50, 95% CI 0.33-0.76). Subgroup analysis of OI etiological categories (viral, parasitic, fungal and Mycobacterial) suggests the possibility of specific protection from fungal infections (OR 0.54. 95% CI 0.32-0.93; PBonferroni corrected = 0.08). We observe an association of APOL1 variant alleles with host protection against OI in HIV-positive individuals. The study suggests a broader role of APOL1 variant alleles in innate immunity in vivo. An et al. determine the presence of variants of the innate immune factor APOL1 in four cohorts of HIV-positive patients. The study suggests that APOL1 might confer carriers of two variant alleles protection from HIV related opportunistic infections, especially fungal infections. [ABSTRACT FROM AUTHOR]