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The combination of machine learning (ML) and electronic health records (EHR) data may be able to improve outcomes of hospitalized COVID-19 patients through improved risk stratification and patient outcome prediction. However, in resource constrained environments the clinical utility of such data-driven predictive tools may be limited by the cost or unavailability of certain laboratory tests. We leveraged EHR data to develop an ML-based tool for predicting adverse outcomes that optimizes clinical utility under a given cost structure. We further gained insights into the decision-making process of the ML models through an explainable AI tool. This cohort study was performed using deidentified EHR data from COVID-19 patients from ProMedica Health System in northwest Ohio and southeastern Michigan. We tested the performance of various ML approaches for predicting either increasing ventilatory support or mortality. We performed post hoc analysis to obtain optimal feature sets under various budget constraints. We demonstrate that it is possible to achieve a significant reduction in cost at the expense of a small reduction in predictive performance. For example, when predicting ventilation, it is possible to achieve a 43% reduction in cost with only a 3% reduction in performance. Similarly, when predicting mortality, it is possible to achieve a 50% reduction in cost with only a 1% reduction in performance. This study presents a quick, accurate, and cost-effective method to evaluate risk of deterioration for patients with SARS-CoV-2 infection at the time of clinical evaluation.

The global pandemic of the SARS-CoV-2 coronavirus has significantly strained hospital resources worldwide. Improved understanding of the COVID-19 disease trajectory for patients requiring hospitalization would allow for the development of more targeted preventative, diagnostic and therapeutic strategies. A covariate-dependent, continuous-time hidden Markov model with four states (moderate-illness, severe-illness, discharged, and deceased) was used to model the dynamic progression of COVID-19 during the course of hospitalization. All model parameters were estimated using the electronic health records of 1,362 patients from ProMedica Health System admitted between March 20, 2020 and December 29, 2020 with a positive nasopharyngeal PCR test for SARS-CoV-2. Demographic characteristics, co-morbidities, vital signs and laboratory test results were retrospectively evaluated to predict clinical progression and outcomes. Several patient-level covariates were associated with differential impacts on the risk of progression. Specifically, while being male, being black or having a medical co-morbidity were all associated with an increased risk of progressing from the moderate to severe disease state, these factors resulted in a decreased risk of transitioning from the severe to the deceased disease state. Body mass index (BMI) alone was not found to be associated with an increased risk of disease progression, while higher age was associated with an increased risk in progressing from moderate to severe and from severe to deceased states. Regardless of the differential risk profiles, all covariates considered other than BMI and asthma were associated with an overall increased risk of transitioning to the deceased state. Recent studies have not included analyses of the temporal progression of COVID-19, making the current study a unique modeling-based approach to understand the dynamics of COVID-19 in hospitalized patients. Such dynamic risk stratification models have the potential not only to improve clinical outcomes in COVID-19, but also a myriad of other acute and chronic diseases that, to date, have largely been assessed only by static modeling techniques.

We were the first to previously report that microcystin-LR (MC-LR) has limited effects within the colons of healthy mice but has toxic effects within colons of mice with pre-existing inflammatory bowel disease. In the current investigation, we aimed to elucidate the mechanism by which MC-LR exacerbates colitis and to identify effective therapeutic targets. Through our current investigation, we report that there is a significantly greater recruitment of macrophages into colonic tissue with pre-existing colitis in the presence of MC-LR than in the absence of MC-LR. This is seen quantitatively through IHC staining and the enumeration of F4/80-positive macrophages and through gene expression analysis for Cd68, Cd11b, and Cd163. Exposure of isolated macrophages to MC-LR was found to directly upregulate macrophage activation markers Tnf and Il1b. Through a high-throughput, unbiased kinase activity profiling strategy, MC-LR-induced phosphorylation events were compared with potential inhibitors, and doramapimod was found to effectively prevent MC-LR-induced inflammatory responses in macrophages.

The rapid increase in use of electronic-cigarettes (e-cigarettes), especially among youth, raises the urgency for regulating bodies to make informed decisions, guidance, and policy on these products. This study evaluated cardiac function in an experimental model following exposure to e-cigarettes. We subjected C57BL/6 mice to e-cigarette vaping for 2-weeks, and cardiac function was assessed using echocardiography. Cardiac tissues were collected at the end of e-cigarette exposure for pathological analysis. The experimental data showed that e-cigarette vaping (3 h/day for 14 days) had no significant effect on cardiac contractility as measured by ejection fraction. However, it significantly increased angiogenesis in mouse heart tissue. We found that e-cigarette exposure increased the endothelial cell marker CD31 and CD34 to approximately 2 fold (p

Vascular calcification (VC) is one of the major causes of cardiovascular morbidity and mortality in patients with chronic kidney disease (CKD). VC is a complex process expressing similarity to bone metabolism in onset and progression. VC in CKD is promoted by various factors not limited to hyperphosphatemia, Ca/Pi imbalance, uremic toxins, chronic inflammation, oxidative stress, and activation of multiple signaling pathways in different cell types, including vascular smooth muscle cells (VSMCs), macrophages, and endothelial cells. In the current review, we provide an in-depth analysis of the various kinds of VC, the clinical significance and available therapies, significant contributions from multiple cell types, and the associated cellular and molecular mechanisms for the VC process in the setting of CKD. Thus, we seek to highlight the key factors and cell types driving the pathology of VC in CKD in order to assist in the identification of preventative, diagnostic, and therapeutic strategies for patients burdened with this disease.

Objective: Cardiotonic steroids (CTS) are known ligands of the Na+/K+-ATPase (NKA) and chronic elevations in volume expanded conditions such as hypertension and chronic kidney disease (CKD) can mediate a pro-inflammatory and pro-fibrotic phenotype. Paraoxonase1 (PON1) is a lactonase enzyme that circulates bound to HDL and possesses antioxidant, anti-inflammatory and anti-atherogenic properties. PON1 can hydrolyze CTS to inactive open-ring forms making them incapable of stimulating NKA and initiating pro-inflammatory signaling cascades. Diminished PON1 activity results in detrimental clinical outcomes in the context of CKD but whether reduced PON1 activity is mechanistically linked to adverse cardiovascular events in CKD remains unknown. We hypothesized that PON-1 can attenuate progression of cardiac inflammation in CKD via modulating the pathogenic pathways induced by CTS signaling using a well characterized Dahl salt-sensitive rat model of hypertensive renal disease and elevated CTS. Methods: Dahl salt-sensitive wild type ( SS-WT ), PON1 knockout ( SS-PON1KO ), and PON1 knockout rats treated with 3E9 anti-CTS antibody (3E9 mAb,50μg/kg i.p. every week for a total of 4 injections) were fed a high salt (8%) diet for five weeks to induce hypertensive renal disease and elevate CTS levels. H&E staining was performed on hearts to analyze immune cell infiltration. Real-time PCR (RT-PCR) analysis was performed for markers of inflammation (IL6, IL1β, and CCL2), hypertrophy (Myh7, NPPA, and Slc8a), and fibrosis (Timp1). Results: RT-PCR analysis revealed significantly increased (≥1.5 fold) expression of cardiac inflammatory (pSS-PON1 KO compared to SS-WT rats after high salt feeding. Treatment of SS-PON1 KO rats with 3E9 mAb significantly decreased (≥ 2.5 fold) expression of Timp1, IL6, Ccl2, IL1β, NPPA, Myh7 and Slc8a (all pSS-PON1KO rats treated with 3E9 mAb compared to SS-PON-1 KO rats (3.5±0.5 VS1.813±0.4094,p Conclusion: Our findings suggest that PON-1 via its counter-regulatory mechanism of the CTS signaling axis exhibits a cardioprotective role in chronic kidney disease.

Background: Paraoxonase 3 (Pon3), is one of the three isoforms of the paraoxonase gene family. While Pon1 and Pon2 are widely studied, there is a paucity of knowledge regarding Pon3. Pon3 is synthesized in the liver and can circulate bound to high-density lipoproteins. There is significant expression in the kidney also. Pon3 has the ability to metabolize eicosanoids, which can act as signaling molecules and have known roles in the pathophysiology of some renal diseases. Decreased Pon activity is associated with elevated levels of eicosanoid metabolites and adverse clinical outcomes. We tested the hypothesis that targeted disruption of Pon3 results in elevated levels of pro-inflammatory eicosanoids and progression of renal injury. Methods/ Results: Ten week old male Dahl salt-sensitive (SS rats) and Pon3 mutant rats (SS Pon3 KO) were maintained on 8% high salt diet for eight weeks, to initiate salt-sensitive hypertensive renal disease. Previously we observed that SS Pon3 KO rats on eight weeks high salt diet demonstrated significantly increased phenotypic renal injury and mortality. In the current study, we noted that SS Pon3 KO had significantly decreased (pPon3 KO and SS wild type rats at the end of eight weeks of high salt diet. We found that hydroxyl fatty acids 5-HEPE and 5-HETE (5-lipoxygenase dependent arachidonic acid metabolites) were significantly (pPon3 KO compared to SS wild type rats. In addition to being mediators of inflammation, these metabolites are associated with renal cell injury and death. Furthermore, prostaglandin 6-keto-PGF 1α , which has known links to renal inflammation, was significantly (pPon3 KO compared to SS wild type rats. Conclusion: These findings suggest that targeted deletion of Pon3 increases pro-inflammatory eicosanoids (5-HETE and 5-HEPE) and prostaglandins (6-keto-PGF 1α ), as well as increases renal damage independent of blood pressure.

Viral entry mechanisms for severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) are an important aspect of virulence. Proposed mechanisms involve host cell membrane-bound angiotensin-converting enzyme 2 (ACE2) and type II transmembrane serine proteases (TTSPs), such as transmembrane serine protease isoform 2 (TMPRSS2). The distribution of expression of these genes across cell types representing multiple organ systems in healthy individuals has been recently demonstrated. However, comorbidities such as diabetes and cardiovascular disease are highly prevalent in patients with Coronavirus Disease 2019 (COVID-19) and associated with worse outcomes. Whether these conditions contribute directly to SARS-CoV-2 virulence remain unclear. Here we show that the expression levels of ACE2, TMPRSS2 and other viral entry-related genes are modulated in target organs of select disease states. In tissues such as heart, which normally express ACE2 but minimal TMPRSS2, we found that TMPRSS2 as well as other TTSPs are elevated in individuals with comorbidities vs healthy individuals. Additionally, we found increased expression of viral entry-related genes in the settings of hypertension, cancer or smoking across target organ systems. Our results demonstrate that common comorbidities may contribute directly to SARS-CoV-2 virulence and suggest new therapeutic targets to improve outcomes in vulnerable patient populations.

Background Renal artery stenosis is a common cause of renal ischemia, contributing to the development of chronic kidney disease. To investigate the role of local CD 40 expression in renal artery stenosis, Goldblatt 2‐kidney 1‐clip surgery was performed on hypertensive Dahl salt‐sensitive rats (S rats) and genetically modified S rats in which CD 40 function is abolished ( Cd40 mutant ). Methods and Results Four weeks following the 2‐kidney 1‐clip procedure, Cd40 mutant rats demonstrated significantly reduced blood pressure and renal fibrosis in the ischemic kidneys compared with S rat controls. Similarly, disruption of Cd40 resulted in reduced 24‐hour urinary protein excretion in Cd40 mutant rats versus S rat controls (46.2±1.9 versus 118.4±5.3 mg/24 h; P Cd40 mutant rats versus S rat controls ( P Cd40 mutant rats demonstrated a significant decrease in gene expression of the profibrotic mediator, plasminogen activator inhibitor‐1 ( P P P P PCR assay. Reciprocal renal transplantation documented that CD 40 exclusively expressed in the kidney contributes to ischemia‐induced renal fibrosis. Furthermore, human CD 40‐knockout proximal tubule epithelial cells suggested that suppression of CD 40 signaling significantly inhibited expression of proinflammatory and ‐fibrotic genes. Conclusions Taken together, our data suggest that activation of CD 40 induces a significant proinflammatory and ‐fibrotic response and represents an attractive therapeutic target for treatment of ischemic renal disease.

Background Recent studies have highlighted a critical role for a group of natriuretic hormones, cardiotonic steroid ( CTS ), in mediating renal inflammation and fibrosis associated with volume expanded settings, such as chronic kidney disease. Immune cell adhesion is a critical step in the inflammatory response; however, little is currently understood about the potential regulatory role of CTS signaling in this setting. Herein, we tested the hypothesis that CTS signaling through Na + /K + ‐ ATP ase α‐1 ( NKA α‐1) enhances immune cell recruitment and adhesion to renal epithelium that ultimately advance renal inflammation. Methods and Results We demonstrate that knockdown of the α‐1 isoform of Na/K‐ ATP ase causes a reduction in CTS ‐induced macrophage infiltration in renal tissue as well reduces the accumulation of immune cells in the peritoneal cavity in vivo. Next, using functional adhesion assay, we demonstrate that CTS‐ induced increases in the adhesion of macrophages to renal epithelial cells were significantly diminished after reduction of NKA α‐1 in either macrophages or renal epithelial cells as well after inhibition of NKA α‐1‐Src signaling cascade with a specific peptide inhibitor, pNaK tide in vitro. Finally, CTS‐ induced expression of adhesion markers in both endothelial and immune cells was significantly inhibited in an NKA α‐1‐Src signaling dependent manner in vitro. Conclusions These findings suggest that CTS potentiates immune cell migration and adhesion to renal epithelium through an NKA α‐1–dependent mechanism; our new findings suggest that pharmacological inhibition of this feed‐forward loop may be useful in the treatment of renal inflammation associated with renal disease.

Non-alcoholic fatty liver disease (NAFLD) is a growing global health concern. With a propensity to progress towards non-alcoholic steatohepatitis (NASH), cirrhosis, and hepatocellular carcinoma, NAFLD is an important link amongst a multitude of comorbidities including obesity, diabetes, and cardiovascular and kidney disease. As several in vivo models of hyperglycemia and NAFLD are employed to investigate the pathophysiology of this disease process, we aimed to characterize an in vitro model of hyperglycemia that was amenable to address molecular mechanisms and therapeutic targets at the cellular level. Utilizing hyperglycemic cell culturing conditions, we induced steatosis within a human hepatocyte cell line (HepG2 cells), as confirmed by electron microscopy. The deposition and accumulation of lipids within hyperglycemic HepG2 cells is significantly greater than in normoglycemic cells, as visualized and quantified by Nile red staining. Alanine aminotransferase (ALT) and alkaline phosphatase (ALP), diagnostic biomarkers for liver damage and disease, were found to be upregulated in hyperglycemic HepG2 cells as compared with normoglycemic cells. Suppression of CEACAM1, GLUT2, and PON1, and elevation of CD36, PCK1, and G6PK were also found to be characteristic in hyperglycemic HepG2 cells compared with normoglycemic cells, suggesting insulin resistance and NAFLD. These in vitro findings mirror the characteristic genetic and phenotypic profile seen in Leprdb/J mice, a well-established in vivo model of NAFLD. In conclusion, we characterize an in vitro model displaying several key genetic and phenotypic characteristics in common with NAFLD that may assist future studies in addressing the molecular mechanisms and therapeutic targets to combat this disease.

Background Recent studies have highlighted a critical role for CD40 in the pathogenesis of renal injury and fibrosis. However, little is currently understood about the regulation of CD40 in this setting. Methods We use novel Na/K-ATPase cell lines and inhibitors in order to demonstrate the regulatory function of Na/K-ATPase with regards to CD40 expression and function. We utilize 5/6 partial nephrectomy as well as direct infusion of a Na/K-ATPase ligand to demonstrate this mechanism exists in vivo. Results We demonstrate that knockdown of the α1 isoform of Na/K-ATPase causes a reduction in CD40 while rescue of the α1 but not the α2 isoform restores CD40 expression in renal epithelial cells. Second, because the major functional difference between α1 and α2 is the ability of α1 to form a functional signaling complex with Src, we examined whether the Na/K-ATPase/Src complex is important for CD40 expression. We show that a gain-of-Src binding α2 mutant restores CD40 expression while loss-of-Src binding α1 reduces CD40 expression. Furthermore, loss of a functional Na/K-ATPase/Src complex also disrupts CD40 signaling. Importantly, we show that use of a specific Na/K-ATPase/Src complex antagonist, pNaKtide, can attenuate cardiotonic steroid (CTS)-induced induction of CD40 expression in vitro. Conclusions Because the Na/K-ATPase/Src complex is also a key player in the pathogenesis of renal injury and fibrosis, our new findings suggest that Na/K-ATPase and CD40 may comprise a pro-fibrotic feed-forward loop in the kidney and that pharmacological inhibition of this loop may be useful in the treatment of renal fibrosis.

Background Early rapid declines of kidney function may occur in patients with atherosclerotic renal artery stenosis with institution of medical therapy. The causes and consequences are not well understood. Methods and Results Patients enrolled in the medical therapy–only arm of the CORAL (Cardiovascular Outcomes With Renal Artery Lesions) study were assessed for a rapid decline (RD) in estimated glomerular filtration rate (eGFR), defined as a ≥30% decrease from baseline to either 3 months, 6 months, or both. In the medical therapy–only cohort, eGFR was available in 359 subjects at all time points, the subjects were followed for a median of 4.72 years, and 66 of 359 (18%) subjects experienced an early RD. Baseline log cystatin C (odds ratio, 1.78 [1.11–2.85]; P=0.02), age (odds ratio, 1.04 [1.00–1.07]; P, See Editorial Beige

The burden of cardiovascular disease and death in chronic kidney disease (CKD) outpaces that of the other diseases and is not adequately described by traditional risk factors alone. Diminished activity of paraoxonase (PON)-1 is associated with increased oxidant stress, a common feature underlying the pathogenesis of CKD. We aimed to assess the prognostic value of circulating PON-1 protein and PON lactonase activity on adverse clinical outcomes across various stages and etiologies of CKD. Circulating PON-1 protein levels and PON lactonase activity were measured simultaneously in patients with CKD as well as a cohort of apparently healthy non-CKD subjects. Both circulating PON-1 protein levels and PON lactonase activity were significantly lower in CKD patients compared to the non-CKD subjects. Similarly, across all stages of CKD, circulating PON-1 protein and PON lactonase activity were significantly lower in patients with CKD compared to the non-CKD controls. Circulating PON lactonase activity, but not protein levels, predicted future adverse clinical outcomes, even after adjustment for traditional risk factors. The combination of lower circulating protein levels and higher activity within the CKD subjects were associated with the best survival outcomes. These findings demonstrate that diminished circulating PON lactonase activity, but not protein levels, predicts higher risk of future adverse clinical outcomes in patients with CKD.

The cluster of differentiation 40 (CD40) is activated by the CD40 ligand (CD40L) in a variety of diverse cells types and regulates important processes associated with kidney disease. The CD40/CD40L signaling cascade has been comprehensively studied for its roles in immune functions, whereas the signaling axis involved in local kidney injury has only drawn attention in recent years. Clinical studies have revealed that circulating levels of soluble CD40L (sCD40L) are associated with renal function in the setting of kidney disease. Levels of the circulating CD40 receptor (sCD40), sCD40L, and local CD40 expression are tightly related to renal injury in different types of kidney disease. Additionally, various kidney cell types have been identified as non-professional antigen-presenting cells (APCs) that express CD40 on the cell membrane, which contributes to the interactions between immune cells and local kidney cells during the development of kidney injury. Although the potential for adverse CD40 signaling in kidney cells has been reported in several studies, a summary of those studies focusing on the role of CD40 signaling in the development of kidney disease is lacking. In this review, we describe the outcomes of recent studies and summarize the potential therapeutic methods for kidney disease which target CD40.

Microcystin-leucine arginine (MC-LR) is a potent liver toxin produced by freshwater cyanobacteria, also known as blue-green algae. While harmful algal blooms are increasing in frequency and severity worldwide, there is still no established method for the diagnosis and assessment of MC-LR induced liver damage. The guidelines for MC-LR safe exposure limits have been previously established based on healthy animal studies, however we have previously demonstrated that pre-existing non-alcoholic fatty liver disease (NAFLD) increases susceptiblity to the hepatotoxic effects of MC-LR. In this study, we sought to investigate the suitability of clinically used biomarkers of liver injury, specifically alanine aminotransferase (ALT) and alkaline phosphatase (ALP), as potential diagnostic tools for liver damage induced by chronic low dose administration of MC-LR in the setting of pre-existing NAFLD. In our Leprdb/J mouse model of NAFLD, we found that while MC-LR induced significant histopathologic damage in the setting of NAFLD, gene expression of ALT and ALP failed to increase with MC-LR exposure. Serum ALT and ALP also failed to increase with MC-LR exposure, except for a moderate increase in ALP with the highest dose of MC-LR used (100 μg/kg). In HepG2 human liver epithelial cells, we observed that increasing MC-LR exposure levels do not lead to an increase in ALT or ALP gene expression, intracellular enzyme activity, or extracellular activity, despite a significant increase in MC-LR induced cytotoxicity. These findings demonstrate that ALT and ALP may be unsuitable as diagnostic biomarkers for MC-LR induced liver damage.

Inflammatory Bowel Disease (IBD) is one of the most common gastrointestinal (GI) disorders around the world, and includes diagnoses such as Crohn&rsquo, s disease and ulcerative colitis. The etiology of IBD is influenced by genetic and environmental factors. One environmental perturbagen that is not well studied within the intestines is microcystin-leucine arginine (MC-LR), which is a toxin produced by cyanobacteria in freshwater environments around the world. We recently reported that MC-LR has limited effects within the intestines of healthy mice, yet interestingly has significant toxicity within the intestines of mice with pre-existing colitis induced by dextran sulfate sodium (DSS). MC-LR was found to prolong DSS-induced weight loss, prolong DSS-induced bloody stools, exacerbate DSS-induced colonic shortening, exacerbate DSS-induced colonic ulceration, and exacerbate DSS-induced inflammatory cytokine upregulation. In addition, we previously reported a significant increase in expression of the pro-inflammatory receptor CD40 in the colons of these mice, along with downstream products of CD40 activation, including plasminogen activator inhibitor-1 (PAI-1) and monocyte chemoattractant protein-1 (MCP-1). In the current study, we demonstrate that knocking out CD40 attenuates the effects of MC-LR in mice with pre-existing colitis by decreasing the severity of weight loss, allowing a full recovery in bloody stools, preventing the exacerbation of colonic shortening, preventing the exacerbation of colonic ulceration, and preventing the upregulation of the pro-inflammatory and pro-fibrotic cytokines IL-1&beta, MCP-1, and PAI-1. We also demonstrate the promising efficacy of a CD40 receptor blocking peptide to ameliorate the effects of MC-LR exposure in a proof-of-concept study. Our findings suggest for the first time that MC-LR acts through a CD40-dependent mechanism to exacerbate colitis.

IL-21 is the most recently discovered common gamma-chain cytokine that promotes persistent T-cell responses in chronic infections, autoimmunity and cancer. However, the therapeutic potential of inhibiting the IL-21-BATF signaling axis, particularly in transplant rejection, remains unclear. We used heart transplant models to examine the effects of IL-21 blockade in prevention of chronic cardiac allograft vasculopathy (CAV) using genetic knock-out and therapeutic approaches. Both wild-type C57BL/6 and IL-21-/- strains acutely rejected Balb/c skin grafts and once immunized with this skin graft, rejected Balb/c heart allografts in an accelerated fashion. However, when transplanted with heart grafts from the class-II major histocompatibility complex mutant, B6bm12 mice; wild-type recipients developed CAV, while IL-21-/- recipients were protected, even at day 100 post-transplant. Similarly, BATF-/- recipients, lacking the transcription factor BATF responsible for IL-21 production, did not develop CAV in B6-bm12 heart allografts. Strikingly, in a transient treatment protocol, the development of CAV in wild-type recipients of B6-bm12 hearts allografts was blocked by the administration of IL-21 receptor fusion protein (R-Fc). Thus, we demonstrate that CAV is regulated at least in part by IL-21 signaling and its blockade by genetic approaches or therapy with IL-21R-Fc prevents CAV in mice.

Similar to ischemic preconditioning, high-intensity exercise has been shown to decrease infarct size following myocardial infarction. In this article, we review the literature on beneficial effects of exercise, exercise requirements for cardioprotection, common methods utilized in laboratories to study this phenomenon, and discuss possible mechanisms for exercise-mediated cardioprotection.

Soluble CD40 ligand (sCD40L) has been implicated in the development of renal injury. The CD40 receptor exists in a soluble form, sCD40R, and has been shown to function as a competitive antagonist against CD40 activation. We analyzed whether plasma levels of sCD40L and sCD40R predict changes in renal function in an all-cause chronic kidney disease (CKD) cohort. Stratification of subjects based on sCD40L and sCD40R individually, as well as in combination, demonstrated that sCD40L was directly associated with declines in estimated glomerular filtration rate (eGFR). sCD40R was negatively associated with declines in eGFR. Baseline characteristics following stratification, including systolic blood pressure, history of diabetes mellitus or peripheral vascular disease, primary renal disease classification, and angiotensin converting enzyme inhibitor or angiotensin receptor blocker usage were not significantly different. High sCD40L and low sCD40R were both found to be independent predictors of a decline in eGFR at 1-year follow-up (−7.57%, p = 0.014; −6.39%, p = 0.044). Our data suggest that circulating levels of sCD40L and sCD40R are associated with changes in renal function in patients with CKD. The CD40 decoy receptor, sCD40R, may serve as a potential therapeutic target to attenuate renal function decline.

Microcystins are potent hepatotoxins that have become a global health concern in recent years. Their actions in at-risk populations with pre-existing liver disease is unknown. We tested the hypothesis that the No Observed Adverse Effect Level (NOAEL) of Microcystin-LR (MC-LR) established in healthy mice would cause exacerbation of hepatic injury in a murine model (Leprdb/J) of Non-alcoholic Fatty Liver Disease (NAFLD). Ten-week-old male Leprdb/J mice were gavaged with 50 &mu, g/kg, 100 &mu, g/kg MC-LR or vehicle every 48 h for 4 weeks (n = 15&ndash, 17 mice/group). Early mortality was observed in both the 50 &mu, g/kg (1/17, 6%), and 100 &mu, g/kg (3/17, 18%) MC-LR exposed mice. MC-LR exposure resulted in significant increases in circulating alkaline phosphatase levels, and histopathological markers of hepatic injury as well as significant upregulation of genes associated with hepatotoxicity, necrosis, nongenotoxic hepatocarcinogenicity and oxidative stress response. In addition, we observed exposure dependent changes in protein phosphorylation sites in pathways involved in inflammation, immune function, and response to oxidative stress. These results demonstrate that exposure to MC-LR at levels that are below the NOAEL established in healthy animals results in significant exacerbation of hepatic injury that is accompanied by genetic and phosphoproteomic dysregulation in key signaling pathways in the livers of NAFLD mice.

Activation of the CD40 receptor on the proximal tubular epithelium of the kidney results in fibrosis and inflammation in experimental models of kidney injury. Soluble CD40 ligand is released by activated platelets. The role of CD40-soluble CD40 ligand in patients with ischemic renal disease is unknown. Plasma levels of CD40 and soluble CD40 ligand were measured by enzyme-linked immunosorbent assay in a single center cohort of 60 patients with renal artery stenosis recruited from Salford Royal Hospital, Manchester, United Kingdom. A natural log transformation of CD40 and soluble CD40 ligand was performed to normalize the data. Estimated glomerular filtration rate was used as the primary indicator of renal function. By univariate analysis, low baseline levels of circulating CD40 ( R 2 =0.06; P R 2 =0.08; P =0.022) were associated with loss of kidney function at 1-year follow-up, whereas soluble CD40 ligand was not ( R 2 =0.02; P =ns). In a multiple linear regression model, CD40 ( P P R 2 =0.17; P P =0.06). The CD40/soluble CD40 ligand signaling cascade may be a novel mechanism contributing to the development and progression of renal injury in patients with atherosclerotic renal artery stenosis.

Background Experimental uremic cardiomyopathy causes cardiac fibrosis and is causally related to the increased circulating levels of the cardiotonic steroid, marinobufagenin ( MBG ), which signals through Na/K‐ ATP ase. Rapamycin is an inhibitor of the serine/threonine kinase mammalian target of rapamycin (mTOR) implicated in the progression of many different forms of renal disease. Given that Na/K‐ ATP ase signaling is known to stimulate the mTOR system, we speculated that the ameliorative effects of rapamycin might influence this pathway. Methods and Results Biosynthesis of MBG by cultured human JEG ‐3 cells is initiated by CYP 27A1, which is also a target for rapamycin. It was demonstrated that 1 μmol/L of rapamycin inhibited production of MBG in human JEG ‐2 cells. Male Sprague‐Dawley rats were subjected to either partial nephrectomy ( PN x), infusion of MBG , and/or infusion of rapamycin through osmotic minipumps. PN x animals showed marked increase in plasma MBG levels (1025±60 vs 377±53 pmol/L; P P MBG levels were significantly decreased in PN x‐rapamycin animals compared to PN x (373±46 vs 1025±60 pmol/L; P Conclusions Rapamycin treatment in combination with MBG infusion significantly attenuated cardiac fibrosis. Our results suggest that rapamycin may have a dual effect on cardiac fibrosis through (1) mTOR inhibition and (2) inhibiting MBG‐ mediated profibrotic signaling and provide support for beneficial effect of a novel therapy for uremic cardiomyopathy.

Background We have demonstrated that cardiotonic steroids, such as ouabain, signaling through the Na/K‐ ATP ase, regulate sodium reabsorption in the renal proximal tubule. By direct carbonylation modification of the Pro222 residue in the actuator (A) domain of pig Na/K‐ ATP ase α1 subunit, reactive oxygen species are required for ouabain‐stimulated Na/K‐ ATP ase/c‐Src signaling and subsequent regulation of active transepithelial 22 Na + transport. In the present study we sought to determine the functional role of Pro222 carbonylation in Na/K‐ ATP ase signaling and sodium handling. Methods and Results Stable pig α1 knockdown LLC ‐ PK 1‐originated PY ‐17 cells were rescued by expressing wild‐type rat α1 and rat α1 with a single mutation of Pro224 (corresponding to pig Pro222) to Ala. This mutation does not affect ouabain‐induced inhibition of Na/K‐ ATP ase activity, but abolishes the effects of ouabain on Na/K‐ ATP ase/c‐Src signaling, protein carbonylation, Na/K‐ ATP ase endocytosis, and active transepithelial 22 Na + transport. Conclusions Direct carbonylation modification of Pro224 in the rat α1 subunit determines ouabain‐mediated Na/K‐ ATP ase signal transduction and subsequent regulation of renal proximal tubule sodium transport.

Essential hypertension is a complex polygenic trait. To understand the genetics of Blood pressure (BP) control, loci are mapped using populations derived by crossing several rat strains with the genetically hypertensive rat model, the Dahl SS rat (SS) and validated as BP quantitative trait loci (QTL). Genes located within the mapped BP QTLs are candidates as inherited loci controlling BP, but require further proof. One such mapped locus is on rat chromosome 9, wherein the proof for one of the candidate genes Regulated Endocrine Specific Protein-18 ( Resp18 ), as a BP QTL, is currently inadequate. To ascertain the status of Resp18 as a BP QTL, a custom targeted gene disruption model of Resp18 was developed on the SS background. As a result of this ZFN mediated disruption, a 7 bp deletion occurred within exon 3 of the Resp18 locus, resulting in a truncated protein with 111aa compared to the full length protein consisting of 175aa. Under a high salt dietary regimen, both systolic and diastolic BP of Resp18 mutant rats were significantly increased compared to SS rats (151±3 vs.170±6mmHg; 116±2vs.129±4mmHg n=10-12, p Resp18 mutant rats demonstrated higher proteinuria compared to SS rats (221±14vs.268±14mg of protein/kg body weight/24hr; n=14-25, p Resp18 mutant rat mesenteric arteries demonstrated significantly reduced relaxation as compared to SS rats (n=4, p Resp18 mutant rats compared to SS rats (51±7.3vs.27±2.7meq/L/24hr; 10±0.3 vs. 14±1.4mg/dl/24hr,n=5-8, p Resp18 mutant rat kidneys showed increased fibrosis compared to SS rats. The median survival of Resp18 mutant rats was 259 days, which was significantly lower than the median survival of 309 days for the SS (n=8-16, p Resp18 is a gene associated with the development of hypertension, renal disease and increased mortality in the SS rats. Resp18 is a molecule involved in the secretory pathway and thereby, future studies will be conducted to examine the mechanistic links between Resp18 , its function in the secretory pathway and BP regulation.

Cardiotonic steroids (CTS) are implicated in pathophysiology of uremic cardiomyopathy. In the present study, we tested whether a monoclonal antibody (mAb) against the bufadienolide CTS, marinobufagenin (MBG), alleviates cardiac hypertrophy and fibrosis in partially nephrectomized (PNx) rats.In PNx rats, we compared the effects of 3E9 anti-MBG mAb and of Digibind, an affinity-purified digoxin antibody, on blood pressure and cardiac hypertrophy and fibrosis following 4 weeks after the surgery.In PNx rats, a fourfold elevation in plasma MBG levels was associated with hypertension, increased cardiac levels of carbonylated protein, cardiac hypertrophy, a reduction in cardiac expression of a nuclear transcription factor which is a negative regulator of collagen synthesis, Friend leukemia integration-1 (Fli-1), and an increase in the levels of collagen-1. A single intraperitoneal administration of 3E9 mAb to PNx rats reduced blood pressure by 59 mm Hg for 7 days and produced a significant reduction in cardiac weight and cardiac levels of oxidative stress, an increase in the expression of Fli-1, and a reduction in cardiac fibrosis. The effects of Digibind were similar to those of 3E9 mAb, but were less pronounced.In experimental chronic renal failure, elevated levels of MBG contribute to hypertension and induce cardiac fibrosis via suppression of Fli-1, representing a potential target for therapy.

Introduction: Cd40 has been implicated in renal injury following activation by its ligand (sCD40L), which is released from activated platelets. Previously we have shown that patients with renal ischemia have elevated levels of sCD40L and circulating levels of CD40 predict changes in renal function. We created a novel Cd40 mutant on the background of the genetically hypertensive Dahl S rat (S rat), which is prone to the development of renal disease, in order to determine the role of Cd40 in ischemic renal disease. Hypothesis: Cd40 induces renal fibrosis in renal ischemia. Methods: A novel Cd40 mutant, with targeted disruption of Cd40, was created in the S rat using the zinc-finger nuclease method. Male Cd40 mutant rats weighing between 250-300 g were used (n=8). Eight S rats were used as age-matched controls. Western blot analysis, trichrome staining, and immunohistochemistry were performed on kidney tissue derived from Cd40 mutants and S rats four weeks following two-kidney one clip (2K1C) surgery. Renal function was determined by urinary protein excretion (UPE), and creatinine measurements. Results: The Cd40 mutants when compared to S rats exhibited significantly lower systolic blood pressure four weeks following 2K1C surgery (130 ± 6 vs. 155 ± 4 mmHg, p Conclusions: Mutation of the Cd40 gene decreases renal fibrosis and improves renal function following renal ischemia. Our results indicate that Cd40 contributes to ischemic renal fibrosis and provides a mechanistic rationale for the development of renal dysfunction in ischemic renal disease.

Background. Previous reports demonstrated that digitalis-like cardiotonic steroids (CTS) contribute to the pathogenesis of end-stage renal disease. The goal of the present study was to define the nature of CTS in patients with chronic kidney disease (CKD) and in partially nephrectomized (PNx) rats. Methods. In patients with CKD and in healthy controls, we determined plasma levels of marinobufagenin (MBG) and endogenous ouabain (EO) and erythrocyte Na/K-ATPase activity in the absence and in the presence of 3E9 anti-MBG monoclonal antibody (mAb) and Digibind. Levels of MBG and EO were also determined in sham-operated Sprague–Dawley rats and in rats following 4 weeks of PNx. Results. In 25 patients with CKD plasma, MBG but not EO was increased (0.86 ± 0.07 versus 0.28 ± 0.02 nmol/L, P < 0.01) and erythrocyte Na/K-ATPase was inhibited (1.24 ± 0.10 versus 2.80 ± 0.09 μmol Pi/mL/h, P < 0.01) as compared to that in 19 healthy subjects. Ex vivo, 3E9 mAb restored Na/K-ATPase in erythrocytes from patients with CKD but did not affect Na/K-ATPase from control subjects. Following chromatographic fractionation of uremic versus normal plasma, a competitive immunoassay based on anti-MBG mAb detected a 3-fold increase in the level of endogenous material having retention time similar to that seen with MBG. A similar pattern of CTS changes was observed in uremic rats. As compared to sham-operated animals, PNx rats exhibited 3-fold elevated levels of MBG but not that of EO. Conclusions. In chronic renal failure, elevated levels of a bufadienolide CTS, MBG, contribute to Na/K-ATPase inhibition and may represent a potential target for therapy.

In 1972 Neal Bricker presented the “trade-off” hypothesis in which he detailed the role of physiological adaptation processes in mediating some of the pathophysiology associated with declines in renal function. In the late 1990’s Xie and Askari published seminal studies indicating that the Na+/K+-ATPase (NKA) was not only an ion pump, but also a signal transducer that interacts with several signaling partners. Since this discovery, numerous studies from multiple laboratories have shown that the NKA is a central player in mediating some of these long-term “trade-offs” of the physiological adaptation processes which Bricker originally proposed in the 1970’s. In fact, NKA ligands such as cardiotonic steroids (CTS), have been shown to signal through NKA, and consequently been implicated in mediating both adaptive and maladaptive responses to volume overload such as fibrosis and oxidative stress. In this review we will emphasize the role the NKA plays in this “trade-off” with respect to CTS signaling and its implication in inflammation and fibrosis in target organs including the heart, kidney, and vasculature. As inflammation and fibrosis exhibit key roles in the pathogenesis of a number of clinical disorders such as chronic kidney disease, heart failure, atherosclerosis, obesity, preeclampsia, and aging, this review will also highlight the role of newly discovered NKA signaling partners in mediating some of these conditions.

Objective: The objective of this study was to identify the predictors of distal embolization (DE) during protected renal artery angioplasty and stenting. Background: DE may contribute to worsening renal function after renal artery stenting. The factors associated with DE, rates of platelet-rich emboli, and treatments that may prevent DE during renal stenting have not been evaluated. Methods: The current study evaluated patients randomized to receive an embolic protection device (EPD) in the RESIST trial. Forty-two patients were identified for inclusion in this study. These patients were further randomized to abcizimab (N = 22) or placebo (N = 20). Modification in Diet in Renal Disease glomerular filtration rate (GFR) was used as the primary measure of renal function. Creatinine was measured by a modified Jaffe reaction using the IDMS-traceable assay. The primary endpoint was capture of platelet rich emboli in the angioguard basket. Results: DE occurred in 15/42 (35%) of the patients and platelet rich DE in 10 (24%) of the patients who received an EPD. Of the angiographic characteristics only lesion length was significantly higher in patients with DE (16 ± 7 mm vs. 10 ± 5 mm, P = 0.04). Preprocedural abciximab reduced DE from 42 to 8% (P = 0.02). The rate of platelet rich emboli was 50% with neither abciximab nor a thienopyridine, 36% with thienopyridine only, 15% abciximab only, and 0% in patients who received both a thienopyridine and abciximab. Only Abciximab use was associated with improved renal function at 1-month, thienopyridine was not. Angiographic characteristics including percent stenosis, minimal luminal diameter (MLD), reference diameter, change in MLD, contrast volume, and procedure time were not predictors of DE during renal stenting. Conclusion: Capture of DE and specifically platelet DE are common during protected renal stenting using a filter-type EPD. Abciximab use, and potentially combined thienopyridine and abciximab use, decreased the rate of platelet rich DE; however, only abciximab improved renal function at 1-month. © 2010 Wiley-Liss, Inc.

Background— Preservation of renal function is an important objective of renal artery stent procedures. Although atheroembolization can cause renal dysfunction during renal stent procedures, whether adjunctive use of embolic protection devices or glycoprotein IIb/IIIa inhibitors improves renal function is unknown. Methods and Results— One hundred patients undergoing renal artery stenting at 7 centers were randomly assigned to an open-label embolic protection device, Angioguard, or double-blind use of a platelet glycoprotein IIb/IIIa inhibitor, abciximab, in a 2×2 factorial design. The main effects of treatments and their interaction were assessed on percentage change in Modification in Diet in Renal Disease–derived glomerular filtration rate from baseline to 1 month using centrally analyzed creatinine. Filter devices were analyzed for the presence of platelet-rich thrombus. With stenting alone, stenting and embolic protection, and stenting with abciximab alone, glomerular filtration rate declined ( P P P P =0.08). An interaction was observed between abciximab and embolic protection ( P P Conclusions— Renal artery stenting alone, stenting with embolic protection, and stenting with abciximab were associated with a decline in glomerular filtration rate. An unanticipated interaction between Angioguard and abciximab was seen, with combination therapy better than no treatment or either treatment alone.

High blood pressure is a common cause of chronic kidney disease. Because CD40, a member of the tumor necrosis factor receptor family, has been linked to the progression of kidney disease in ischemic nephropathy, we studied the role of Cd40 in the development of hypertensive renal disease. The Cd40 gene was mutated in the Dahl S genetically hypertensive rat with renal disease by targeted-gene disruption using zinc-finger nuclease technology. These rats were then given low (0.3%) and high (2%) salt diets and compared. The resultant Cd40 mutants had significantly reduced levels of both urinary protein excretion (41.8 ± 3.1 mg/24 h vs. 103.7 ± 4.3 mg/24 h) and plasma creatinine (0.36 ± 0.05 mg/dl vs. 1.15 ± 0.19 mg/dl), with significantly higher creatinine clearance compared with the control S rats (3.04 ± 0.48 ml/min vs. 0.93 ± 0.15 ml/min), indicating renoprotection was conferred by mutation of the Cd40 locus. Furthermore, the Cd40 mutants had a significant attenuation in renal fibrosis, which persisted on the high salt diet. However, there was no difference in systolic blood pressure between the control and Cd40 mutant rats. Thus, these data serve as the first evidence for a direct link between Cd40 and hypertensive nephropathy. Hence, renal fibrosis is one of the underlying mechanisms by which Cd40 plays a crucial role in the development of hypertensive renal disease.

For people enrolled in Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL), we sought to examine whether variation exists in the baseline medical therapy of different geographic regions and if any variations in prescribing patterns were associated with physician specialty. Patients were grouped by location within the United States (US) and outside the US (OUS), which includes Canada, South America, Europe, South Africa, New Zealand, and Australia. When comparing US to OUS, participants in the US took fewer anti-hypertensive medications (1.9 ± 1.5 vs. 2.4 ± 1.4; P < .001) and were less likely to be treated with an angiotensin-converting enzyme inhibitor or angiotensin II receptor blocker (46% vs. 62%; P < .001), calcium channel antagonist (37% vs. 58%; P < .001), and statin (64% vs. 75%; P < .05). In CORAL, the identification of variations in baseline medical therapy suggests that substantial opportunities exist to improve the medical management of patients with atherosclerotic renal-artery stenosis.

Cigarette smoking causes cardiovascular disease and is associated with poor kidney function in individuals with diabetes mellitus and primary kidney diseases. However, the association of smoking on patients with atherosclerotic renal artery stenosis has not been studied. The current study utilized data from the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL, NCT00081731) clinical trial to evaluate the effects of smoking on the risk of cardio-renal events and kidney function in this population. Baseline data showed that smokers (n = 277 out of 931) were significantly younger at enrollment than non-smokers (63.3±9.1 years vs 72.4±7.8 years; p

The diagnosis of renal artery stenosis (RAS) has become increasingly common in part due to greater awareness of ischemic renal disease and increased use of diagnostic techniques. Over 90 % of RAS cases are caused by atherosclerotic renovascular disease (ARVD). Patients with ARVD are at high risk for fatal and nonfatal cardiovascular and renal events. The mortality rate in patients with ARVD is high, especially with other cardiovascular or renal comorbidities. Recent clinical studies have provided substantial evidence concerning medical therapy and endovascular interventional therapeutic approaches for ARVD. Despite previous randomized clinical trials, the optimal therapy for ARVD remained uncertain until the results of the Cardiovascular Outcomes in Renal Atherosclerotic Lesions (CORAL) trial were released recently. CORAL demonstrated that optimal medical therapy was equally effective to endovascular therapy in the treatment of ARVD. Clinicians can now practice with more evidence-based medicine to treat ARVD and potentially decrease mortality in patients with ARVD using optimal medical therapy.

People with atherosclerotic renal artery stenosis may benefit from renin-angiotensin inhibitors, angiotensin-converting enzyme inhibitors, and angiotensin-receptor blockers, but little is known about the factors associated with their use.The Cardiovascular Outcomes in Renal Atherosclerotic Lesions study (ClinicalTrials.gov identified: NCT00081731) is a prospective, international, multicenter clinical trial that randomly assigned participants with atherosclerotic renal artery stenosis who received optimal medical therapy to stenting versus no stenting from May 2005 through January 2010. At baseline, medication information was available from 853 of 931 randomly assigned participants. Kidney function was measured by serum creatinine-based eGFR at a core laboratory.Before randomization, renin-angiotensin inhibitors were used in 419 (49%) of the 853 participants. Renin-angiotensin inhibitor use was lower in those with CKD (eGFR60 ml/min per 1.73 m(2)) (58% versus 68%; P=0.004) and higher in individuals with diabetes (41% versus 27%; P0.001). Presence of bilateral renal artery stenosis or congestive heart failure was not associated with renin-angiotensin inhibitor use. Although therapy with renin-angiotensin inhibitors varied by study site, differences in rates of use were not related to the characteristics of the site participants. Participants receiving a renin-angiotensin inhibitor had lower systolic BP (mean ± SD, 148 ± 23 versus 152 ± 23 mmHg; P=0.003) and more often had BP at goal (30% versus 22%; P=0.01).Kidney function and diabetes were associated with renin-angiotensin inhibitor use. However, these or other clinical characteristics did not explain variability among study sites. Patients with renal artery stenosis who received renin-angiotensin inhibitor treatment had lower BP and were more likely to be at treatment goal.

Gender difference has been suggested as a risk factor for developing cardiovascular and renal diseases in humans and experimental animals. As a major sex hormone, progesterone was reported to compete with cardiotonic steroid binding to Na/K-ATPase. Our previous publication demonstrated that cardiotonic steroids (e.g., marinobufagenin) play an important role in the development of experimental uremic cardiomyopathy. We also observed that the putative mineralocorticoid antagonists, spironolactone and its major metabolite canrenone, antagonize binding of cardiotonic steroids to Na/K-ATPase in a competitive manner and also ameliorate experimental uremic cardiomyopathy induced by partial nephrectomy. In the following studies, we noted that progesterone displayed competitive inhibition of cardiotonic steroid binding to Na/K-ATPase and partially inhibited collagen synthesis induced by marinobufagenin in cultured cardiac fibroblasts. Therefore, we sought to examine whether female rats displayed less uremic cardiomyopathy than male rats when subjected to partial nephrectomy. Although partial nephrectomy caused the induction of smaller increases in blood pressure of female rats, they appeared to be similarly susceptible to cardiac remodeling induced by partial nephrectomy in terms of hypertrophy and fibrosis as age-matched male rats. The possible explanations for our findings are therefore discussed.

Elevated levels of endogenous cardiotonic steroids (CTS) have been reported in a variety of clinical conditions associated with plasma volume expansion, such as congestive heart failure (CHF), chronic renal failure, hypertension (HTN), renal ischemia, and preeclampsia.1 We have shown that the cardiotonic steroid marinobufagenin (MBG), signaling through the Na/K-ATPase pathway, causes many of the adverse pathologic effects of experimental renal disease induced by removal of five-sixths of the kidney (5/6 nephrectomy; PNx) in the rat.2,3 Furthermore, our group has demonstrated that pharmacologic administration of MBG causes cardiac hypertrophy and fibrosis in rats, whereas active immunization against MBG attenuated this in PNx animals.2,3 Additionally, treatment of cardiac fibroblasts with MBG at concentrations similar to those reported in experimental and clinical renal failure has been shown to stimulate collagen production.3 This increase in collagen production appears to depend on the Na/K-ATPase-Src-EGFR-ROS signaling cascade.1,3 We have also demonstrated that MBG induces renal fibrosis by stimulating the transcription factor Snail, leading to epithelial-to-mesenchymal transition (EMT) in the tubular epithelia.4 The transcription factor Friend leukemia integration-1 (Fli-1) has been shown to be a negative regulator of collagen synthesis.5,6 Protein kinase C-δ (PKC-δ) phosphorylates Fli-1 and promotes collagen synthesis.7 Our studies indicate that MBG signaling through the Na/K-ATPase-Src-EGFR-ROS cascade initiated PKC-δ translocation to the nucleus, leading to Fli-1 phosphorylation and collagen production.8 Our laboratory recently reported that treatment with a monoclonal antibody (mAb) directed against MBG (3E9 mAb) in PNx animals drastically decreased their blood pressure, significantly reduced cardiac levels of oxidant stress, increased the expression of Fli-1, and significantly reduced cardiac fibrosis.9 The goals of the current study were to determine whether immunization against MBG through the administration of 3E9 mAb would reduce the development of renal fibrosis, and improve renal function in experimental renal failure.

Renal artery stenosis (RAS) is an important cause of renal failure; however, the factors associated with loss of kidney function in patients with RAS are poorly described, as are the predictors of an improvement in kidney function after stenting. One hundred patients at seven centers undergoing renal stenting were randomly assigned to an embolic protection device or double-blind use of a platelet glycoprotein IIb/IIIa inhibitor. The glomerular filtration rate (GFR) was measured using the creatinine-derived modified Modification of Diet in Renal Disease (MDRD) equation, cystatin C, and iohexol clearance. In univariate and multivariate models, baseline MDRD and cystatin C GFR were associated with congestive heart failure (CHF) ( p = 0.01), lesion length ( p = 0.01), and percent stenosis (–0.27, p = 0.01). In multivariate models, MDRD-estimated GFR 1 month after stenting was associated with bilateral stenosis ( p < 0.05) and lesion length ( p < 0.05), whereas with cystatin C the multivariate model included angiotensin receptor blocker (ARB) ( p < 0.05) and minimal luminal diameter (MLD) ( p < 0.05). The improvement in GFR from baseline to 1 month, measured as percent change, was related to baseline MDRD ( p = 0.009) and cystatin C ( p = 0.03) GFR. For MDRD GFR combined treatment with abciximab and Angioguard® embolic protection ( p = 0.02) remained significant in multivariate analysis as did CHF, which was also significant with cystatin C ( p = 0.05). In conclusion, CHF and lesion characteristics (MLD, percent stenosis and lesion length) are determinants of renal function in patients with RAS. In contrast, the acute improvement in renal function after revascularization is most strongly influenced by baseline GFR, and to a lesser degree CHF and combined procedural treatment with abciximab and embolic protection but not lesion characteristics. Clinical Trial Registration – URL: http://www.clinicaltrials.gov . Unique identifier: NCT00234585

Soluble CD40 ligand (sCD40L) is a marker of platelet activation; whether platelet activation occurs in the setting of renal artery stenosis and stenting is unknown. Additionally, the effect of embolic protection devices and glycoprotein IIb/IIIa inhibitors on platelet activation during renal artery intervention is unknown.Plasma levels of sCD40L were measured in healthy controls, patients with atherosclerosis without renal stenosis, and patients with renal artery stenosis before, immediately after, and 24 hours after renal artery stenting.Soluble CD40L levels were higher in renal artery stenosis patients than normal controls (347.5 ± 27.0 versus 65.2 ± 1.4 pg/ml, P0.001), but were similar to patients with atherosclerosis without renal artery stenosis. Platelet-rich emboli were captured in 26% (9 of 35) of embolic protection device patients, and in these patients sCD40L was elevated before the procedure. Embolic protection device use was associated with a nonsignificant increase in sCD40L, whereas sCD40L declined with abciximab after the procedure (324.9 ± 42.5 versus 188.7 ± 31.0 pg/ml, P = 0.003) and at 24 hours.Atherosclerotic renal artery stenosis is associated with platelet activation, but this appears to be related to atherosclerosis, not renal artery stenosis specifically. Embolization of platelet-rich thrombi is common in renal artery stenting and is inhibited with abciximab.

Cardiotonic steroids, including marinobufagenin, are a group of new steroid hormones found in plasma and urine of patients with congestive heart failure, myocardial infarction, and chronic renal failure. In animal studies, partial nephrectomy induces marinobufagenin elevation, cardiac hypertrophy, and fibrosis. The objective of this study is to test the effect of renal ischemia on marinobufagenin levels in humans with renal artery stenosis (RAS). To test this, plasma marinobufagenin levels were measured in patients with RAS of the Prospective Randomized Study Comparing Renal Artery Stenting With or Without Distal Protection, non-RAS patient controls who were scheduled for coronary angiography, and normal healthy individuals. Marinobufagenin levels were significantly higher in patients with RAS compared with those of the other 2 groups. Multivariate analysis shows that occurrence of RAS is independently related to marinobufagenin levels. In addition, renal artery revascularization by stenting partially reversed marinobufagenin levels in the patients with RAS (0.77±0.06 nmol/L at baseline; 0.66±0.06 nmol/L at 24 hours; and 0.61±0.05 nmol/L at 1 month). In conclusion, we have found that marinobufagenin levels are increased in patients with RAS, whereas reversal of renal ischemia by stenting treatment reduces marinobufagenin levels. These results suggest that RAS-induced renal ischemia may be a major cause of marinobufagenin release.

Objective: The aim of this study was to evaluate whether complete embolic protection is superior to partial embolic protection for preservation of kidney function during renal artery angioplasty and stenting. Background: Renal artery angioplasty and stenting (RAAS) is a common treatment for atherosclerotic renal artery stenosis. However, RAAS may be complicated by peri-procedural loss of kidney function. Methods: In total, 44 patients were randomized to embolic protection devices (EPD) use; 25 complete and 19 partial embolic protection. These patients were further randomized to receive abciximab (n = 23) or placebo (n = 20). MDRD glomerular filtration rate (GFR), was used as the primary measure of renal function. Creatinine was measured by a modified Jaffe reaction using the IDMS-traceable assay. The primary endpoint was the percent change in estimated glomerular filtration rate (eGFR) 1 month following stent placement. Results: There was no difference in percent change eGFR at 1 month between complete or partial protection (−4 ± 25 vs. +3 ± 30, P = 0.45). Abciximab was associated with a net improvement in eGFR when compared with placebo (+0.5 ± 27 vs. −11 ± 20, P = 0.04). On subgroup analysis, the use of abciximab was associated with significantly improved eGFR in the partial distal embolic protection group (+14 ± 33 vs. −17 ± 13 %, P = 0.018) but not in the complete distal embolic protection group (+2.5 ± 26 vs. −11 ± 24, P = 0.42), however, there was no interaction between completeness of protection and abciximab on eGFR (P = ns). Capture of embolic material was more likely with complete protection when compared with those receiving partial protection (51% vs. 21%, P < 0.05). Conclusion: Complete protection was superior to partial protection for the capture of athermanous debris during renal artery stenting. However, this was not associated with improved renal function. Importantly, Abciximab conferred a benefit for renal function that was independent of the degree of embolic protection. © 2008 Wiley-Liss, Inc.