Environmental risk factors for reduced kidney function due to undetermined cause in India: an environmental epidemiologic analysis

BACKGROUND

An epidemic of chronic kidney disease is occurring in rural communities in low-income and middle-income countries that do not share common kidney disease risk factors such as diabetes and hypertension. This chronic kidney disease of unknown etiology occurs primarily in agricultural communities in Central America and South Asia. Consequently, environmental risk factors including heat stress, heavy metals exposure, and low altitude have been hypothesized as risk factors. We conducted an environmental epidemiological analysis investigating these exposures in India which reports the disease.

METHODS

We used a random sample population in rural and urban sites in Northern and Southern India in 2010, 2011, and 2014 (n = 11,119). We investigated associations of the heat index, altitude, and vicinity to cropland with estimated glomerular filtration rate (eGFR) using satellite-derived data assigned to residential coordinates. We modeled these exposures with eGFR using logistic regression to estimate the risk of low eGFR, and linear mixed models (LMMs) to analyze site-specific eGFR-environment associations.

RESULTS

Being over 55 years of age, male, and living in proximity to cropland was associated with increased risk of low eGFR [odds ratio (OR) (95% confidence interval (CI) = 2.24 (1.43, 3.56), 2.32 (1.39, 3.88), and 1.47 (1.16, 2.36)], respectively. In LMMs, vicinity to cropland was associated with low eGFR [-0.80 (-0.44, -0.14)]. No associations were observed with temperature or altitude.

CONCLUSIONS

Older age, being male, and living in proximity to cropland were negatively associated with eGFR. These analyses are important in identifying subcommunities at higher risk and can help direct future environmental investigations.

Impact of Sofosbuvir-Based Regimens for the Treatment of Hepatitis C After Liver Transplant on Renal Function: Results of a Canadian National Retrospective Study

OBJECTIVES

We assessed the impact of sofosbuvir-based regimens on renal function in liver transplant recipients with recurrent hepatitis C virus and the role of renal function on the efficacy and safety of these regimens.

MATERIALS AND METHODS

In an expanded pan-Canadian cohort, 180 liver transplant recipients were treated with sofosbuvir-based regimens for hepatitis C virus recurrence from January 2014 to May 2015. Mean age was 58 ± 6.85 years, and 50% had F3/4 fibrosis. Patients were stratified into 4 groups based on baseline estimated glomerular filtration rate (calculated by the Modification of Diet in Renal Disease formula): < 30, 30 to 45, 46 to 60, and > 60 mL/min/173 m2. The primary outcome was posttreatment changes in renal function from baseline. Secondary outcomes included sustained virologic response at 12 weeks posttreatment and anemia-related and serious adverse events.

RESULTS

Posttreatment renal function was improved in most patients (58%). Renal function declined in 22% of patients, which was more marked in those with estimated glomerular filtration rate < 30 mL/min/173 m2, advanced cirrhosis (P = .05), and aggressive hepatitis C virus/fibrosing cholestatic hepatitis (P < .05). High rates (80%-88%) of sustained virologic response at 12 weeks posttreatment were seen across all renal function strata. Cirrhotic patients with glomerular filtration rates < 30 mL/min/173 m2 had sustained virologic response rates at 12 weeks posttreatment comparable to the overall patient group. Rates of anemia-related adverse events and transfusion requirements increased across decreasing estimated glomerular filtration rate groups, with notably more occurrences with ribavirin-based regimens.

CONCLUSIONS

Sofosbuvir-based regimens improved overall renal function in liver transplant recipients, with sustained virologic response, suggesting an association of subclinical hepatitis C virus-related renal disease. Sustained virologic response rates at 12 weeks posttreatment (80%-88%) were comparable regardless of baseline renal function but lower in cirrhosis.

Cost-effectiveness analysis of elbasvir-grazoprevir regimen for treating hepatitis C virus genotype 1 infection in stage 4-5 chronic kidney disease patients in France

Objective

To assess the cost-effectiveness of the elbasvir/grazoprevir (EBR/GZR) regimen in patients with genotype 1 chronic hepatitis C virus (HCV) infection with severe and end-stage renal disease compared to no treatment.

Design

This study uses a health economic model to estimate the cost-effectiveness of treating previously untreated and treatment experienced chronic hepatitis C patients who have severe and end stage renal disease with the elbasvir-grazoprevir regimen versus no treatment in the French context. The lifetime homogeneous markovian model comprises of forty combined health states including hepatitis C virus and chronic kidney disease. The model parameters were from a multicentre randomized controlled trial, ANRS CO22 HEPATHER French cohort and literature. 1000 Monte Carlo simulations of patient health states for each treatment strategy are used for probabilistic sensitivity analysis and 95% confidence intervals calculations. The results were expressed in cost per quality-adjusted life year (QALY) gained.

Patients

The mean age of patients in the HEPATHER French cohort was 59.6 years and 56% of them were men. 22.3% of patients had a F0 fibrosis stage (no fibrosis), 24.1% a F1 stage (portal fibrosis without septa), 7.1% a F2 stage (portal fibrosis with few septa), 21.4% a F3 stage (numerous septa without fibrosis) and 25% a F4 fibrosis stage (compensated cirrhosis). Among these HCV genotype 1 patients, 30% had severe renal impairment stage 4, 33% had a severe renal insufficiency stage 5 and 37% had terminal severe renal impairment stage 5 treated by dialysis.

Intervention

Fixed-dose combination of direct-acting antiviral agents elbasvir and grazoprevir compared to no-treatment.

Results

EBR/GZR increased the number of life years (6.3 years) compared to no treatment (5.1 years) on a lifetime horizon. The total number of QALYs was higher for the new treatment because of better utility on health conditions (6.2 versus 3.7 QALYs). The incremental cost-utility ratio (ICUR) was of €15,212 per QALY gained for the base case analysis.

Conclusions

This cost-utility model is an innovative approach that simultaneously looks at the disease evolution of chronic hepatitis C and chronic kidney disease. EBR/GZR without interferon and ribavirin, produced the greatest benefit in terms of life expectancy and quality-adjusted life years (QALY) in treatment-naïve or experienced patients with chronic hepatitis C genotype 1 and stage 4–5 chronic kidney disease including dialysis patients. Based on shape of the acceptability curve, EBR/GZR can be considered cost-effective at a willingness to pay of €20,000 /QALY for patients with renal insufficiency with severe and end-stage renal disease compared to no treatment.

Role of mesenchymal stem cells versus angiotensin converting enzyme inhibitor in kidney repair

AIM

The current study sought to clarify the role of bone marrow derived mesenchymal stem cells (BM-MSCs) and adipose tissue derived mesenchymal stem cells (AD-MSCs) in repressing nephropathy in the experimental model. Moreover, the aim of this work was extended to compare between stem cells role and angiotensin converting enzyme inhibitor in kidney repair.

METHODS

Isolation and preparation of MSCs culture, flow cytometry using CD34, CD44 and CD105 cell surface markers, biochemical analyses for determination of serum creatinine, urea, transforming growth factor β (TGF-β), cystatin C (CYS-C) and urinary N-Acetyl-ß-D-Glucosaminidase (UNAG), and histopathological investigation of kidney tissue sections were performed.

RESULTS

The results of the present study revealed that single intravenous infusion of MSCs either derived from bone marrow or adipose tissue was able to enhance renal reparative processes through significantly decreased serum creatinine, urea, TGF-β and CYS-C levels as well as UNAG level and significantly increase glomerular filtration rate. Additionally, the histopathological investigations of kidney tissues showed that MSCs have significant regenerative effects as evidenced by the decrease in focal inflammatory cells infiltration, focal interstitial nephritis and congested glomeruli as well as degenerated tubules.

CONCLUSION

The current data provided distinct evidence about the favourable impact of AD-MSCs and BM-MSCs in attenuation of cyclosporine-induced nephropathy in rats through their ability to promote functional and structural kidney repair via transdifferentiation.

Polydatin promotes Nrf2-ARE anti-oxidative pathway through activating CKIP-1 to resist HG-induced up-regulation of FN and ICAM-1 in GMCs and diabetic mice kidneys

Our previous study indicated that Casein kinase 2 interacting protein-1 (CKIP-1) could promote the activation of the nuclear factor E2-related factor 2 (Nrf2)/ antioxidant response element (ARE) pathway, playing a significant role in inhibiting the fibrosis of diabetic nephropathy (DN). Polydatin (PD) has been shown to possess strong resistance effects on renal fibrosis which is closely related to activating the Nrf2/ARE pathway, too. Whereas, whether PD could resist DN through regulating CKIP-1 and consequently promoting the activation of Nrf2-ARE pathway needs further investigation. Here, we found that PD significantly reversed the down-regulation of CKIP-1 and attenuated fibronectin (FN) and intercellular cell adhesion molecule-1 (ICAM-1) in glomerular mesangial cells (GMCs) exposed to high glucose (HG). Moreover, PD could decrease Keap1 expression and promote the nuclear content, ARE-binding ability, and transcriptional activity of Nrf2. The activation of Nrf2-ARE pathway by PD eventually led to the quenching of hydrogen peroxide (H₂O₂) and superoxide overproduction boosted by HG. Depletion of CKIP-1 blocked the Nrf2-ARE pathway activation and reversed FN and ICAM-1 down-regulation induced by PD in GMCs challenged with HG. PD increased CKIP-1 and Nrf2 levels in the kidney tissues as well as improved the anti-oxidative effect and renal dysfunction of diabetic mice, which eventually reversed the up-regulation of FN and ICAM-1. Experiments above suggested that PD could increase the CKIP-1-Nrf2-ARE pathway activation to prevent the OSS-induced insult in GMCs and diabetic mice which effectively postpone the diabetic renal fibrosis and the up-regulation of CKIP-1 is probably a novel mechanism in this process.

New molecular insights in diabetic nephropathy

Diabetes mellitus represents one of the major causes of functional kidney impairment. The review highlights the most significant steps made over the last decades in understanding the molecular basis of diabetic nephropathy (DN), which may provide reliable biomarkers for early diagnosis and prognosis, along with new molecular targets for personalized medicine. There is an increased interest in developing new therapeutic strategies to slow DN progression for improving patients' quality of life and reducing all-cause morbidity and disease-associated mortality. It is highly important to have a science-based medical attitude when facing diabetic patients with associated comorbidities and risk of rapid evolution toward end-stage renal disease. The data discussed herein were mainly from MEDLINE and PubMed articles published in English from 1990 to 2015 and from up-to-date. The search term was "diabetic nephropathy and oxidative stress".