Global dimensions of chronic kidney disease of unknown etiology (CKDu): a modern era environmental and/or occupational nephropathy?

Kidney Care in Times of Crises: A Review

The global burden of kidney disease is increasing, paralleled by a rising number of natural and man-made crises. During these tumultuous times, accessing vital healthcare resources becomes challenging, posing significant risks to individuals, particularly those with kidney disease. This review delves into the impact of crises on kidney disease, with a particular focus on acute kidney injury (AKI), kidney failure (KF), and kidney transplant (KT). Patients experiencing crush injuries leading to AKI may encounter delayed diagnosis due to the chaotic nature of disasters and limited availability of resources. In chronic crises, such as conflicts, patients with KF are particularly affected, and deviations from dialysis standards are unfortunately common, impacting morbidity and mortality rates. Additionally, crises also disrupt access to kidney transplants, potentially compromising transplant outcomes. This review underscores the critical importance of preparedness measures and proactive management for kidney disease in crisis settings. Collaborative efforts among government bodies, rescue teams, healthcare providers, humanitarian agencies, and nongovernmental organizations are imperative to ensure equitable and reasonable care for kidney disease patients during times of crises, with the aim of saving lives and improving outcomes.

Chronic kidney disease of unknown aetiology in Africa: A review of the literature

During the last two decades, an epidemic of a severe form of chronic kidney disease (CKD) unrelated to traditional risk factors (diabetes and hypertension) has been recognized in low- to middle-income countries. CKD of unknown aetiology (CKDu) mainly affects young working-age adults, and has become as an important and devastating public health issue. CKDu is a multifactorial disease with associated genetic and environmental risk factors. This review summarizes the current epidemiological evidence on the burden of CKDu and its probable environmental risk factors contributing to CKD in Africa. PubMed/Medline and the African Journals Online databases were searched to identify relevant population-based studies published in the last two decades. In the general population, the burden of CKD attributable to CKDu varied from 19.4% to 79%. Epidemiologic studies have established that environmental factors, including genetics, infectious agents, rural residence, low socioeconomic status, malnutrition, agricultural practise and exposure to agrochemicals, heavy metals, use of traditional herbs, and contaminated water sources or food contribute to the burden of CKD in the region. There is a great need for epidemiological studies exploring the true burden of CKDu and unique geographical distribution, and the role of environmental factors in the development of CKD/CKDu.

Characteristics and clinical outcomes of patients with kidney failure of unknown aetiology from ANZDATA registry

INTRODUCTION

Kidney failure of unknown aetiology (uESKD) is also heavily location dependent varying between 27% in Egypt to 54% in Aguacalientes, Mexico. There is limited information about the characteristics of people with uESKD in Australia and New Zealand, as well as their clinical outcomes on kidney replacement therapy.

METHODS

Data on people commencing kidney replacement therapy 1989-2021 were received from the Australia and New Zealand Dialysis and Transplant (ANZDATA) registry. Primary exposure was cause of kidney failure-uESKD or non-uESKD (known-ESKD). Primary outcome was mortality. Secondary outcome was kidney transplantation. Dialysis and transplant cohorts were analysed separately. Cox Proportional Hazards Regression models were used to evaluate correlations between cause of kidney failure and mortality risk. Subgroup analyses were completed to compare mortality risk in people with uESKD to those with diabetic nephropathy, autosomal dominant polycystic kidney disease (ADPKD), glomerular disease and other kidney diseases.

RESULTS

This study included 60,448 people on dialysis and 20,859 transplant recipients. 1-year, 3-year and 5-year mortality rates in people with uESKD on dialysis were 31.6%, 58.7% and 77.2%, respectively. 1-year, 3-year and 5-year mortality rates in transplant recipients with uESKD were 2.8%, 13.8% and 24.0%, respectively. People with uESKD on dialysis had a higher mortality risk compared to those without uESKD on univariable and multivariable analyses (adjusted hazard ratio [AHR] 1.10, 95% CI 1.06-1.16, p<0.001). Transplant recipients with uESKD have a higher mortality risk compared to those without uESKD on univariable and multivariable analyses (AHR 1.17, 95% CI 1.01-1.35, p<0.05). People with uESKD had similar likelihood of kidney transplantation compared to people with known-ESKD.

CONCLUSION

People with uESKD on kidney replacement therapy have higher mortality risk compared to people with other kidney diseases. Further studies are required to identify contributing factors to these findings.

Chronic dehydration induces injury pathways in rats, but does not mimic histopathology of chronic interstitial nephritis in agricultural communities

CINAC-patients present renal proximal tubular cell lysosomal lesions which are also observed in patients experiencing calcineurin inhibitor (CNI) nephrotoxicity, suggesting that CINAC is a toxin-induced nephropathy. An alternative hypothesis advocates chronic dehydration as a major etiological factor for CINAC. Here, we evaluated histological and molecular changes in dehydrated versus toxin exposed rats. Wistar rats were divided in 3 groups. Group 1 (n = 6) had free access to drinking water (control group). Group 2 (n = 8) was water deprived for 10 h per 24 h, 5 days/week and placed in an incubator (37 °C) for 30 min/h during water deprivation. Group 3 (n = 8) underwent daily oral gavage with cyclosporine (40 mg/kg body weight). After 28 days, renal function, histopathology and proteomic signatures were analysed. Cyclosporine-treated rats developed focal regions of atrophic proximal tubules with associated tubulo-interstitial fibrosis. PASM staining revealed enlarged argyrophilic granules in affected proximal tubules, identified as lysosomes by immunofluorescent staining. Electron microscopy confirmed the enlarged and dysmorphic phenotype of the lysosomes. Overall, these kidney lesions resemble those that have been previously documented in farmers with CINAC. Dehydration resulted in none of the above histopathological features. Proteomic analysis revealed that dehydration and cyclosporine both induce injury pathways, yet of a clear distinct nature with a signature of toxicity only for the cyclosporine group. In conclusion, both cyclosporine and dehydration are injurious to the kidney. However, dehydration alone does not result in kidney histopathology as observed in CINAC patients, whereas cyclosporine administration does. The histopathological analogy between CINAC and calcineurin inhibitor nephrotoxicity in rats and humans supports the involvement of an as-yet-unidentified environmental toxin in CINAC etiology.

Probiotics mitigate kidney damage after exposure to Sri Lanka's local groundwater from chronic kidney disease with uncertain etiology (CKDu) prevalent area in zebrafish

Groundwater in Sri Lanka, contaminated with environmental toxins, is suspected to potentially induce chronic kidney disease of uncertain etiology (CKDu) in humans. This study aims to elucidate the potential mitigating effects of probiotics on kidney damage induced by exposure to this local groundwater (LW) in zebrafish. We used zebrafish as a model organism and exposed them to local groundwater to evaluate the risk of CKDu. Probiotics were then added at a concentration of 108 colony-forming units per milliliter (CFU/mL). Our findings revealed that exposure to local groundwater resulted in abnormalities, such as tail deletion and spinal curvature in zebrafish larvae. However, the addition of probiotics mitigated these effects, improving the hatching rate, heart rate, length, weight, deformity rate, survival rate, and abnormal behavior of zebrafish. It also positively influenced the differential expression levels of kidney development and immunity-related genes (dync2h1, foxj1, pkd2, gata3, slc20a1, il1β, and lyso). Furthermore, exposure to LW decreased both the diversity and abundance of microbiota in zebrafish larvae. However, treatment with probiotics, such as L. plantarum and L. rhamnosus partially restored the disrupted gut microbiota and significantly impacted the cellular process pathways of the microbial community, as determined by KEGG (Kyoto Encyclopedia of Genes and Genomes) analysis. In conclusion, this study highlights the risks associated with Sri Lanka's local groundwater from a CKDu prevalent area and confirms the beneficial effects of different probiotics. These findings may provide new insights into bacterial function in host kidney health.

Elucidating environmental factors and their combined effects on CKDu in Sri Lanka using zebrafish

Chronic kidney disease with uncertain etiology (CKDu) in Sri Lanka has attracted much attention as a global health issue. However, how environmental factors in local drinking water induce kidney damage in organisms is still elusive. We investigated multiple environmental factors including water hardness and fluoride (HF), heavy metals (HM), microcystin-LR (MC-LR), and their combined exposure (HFMM) to elucidate their toxic effects on CKDu risk in zebrafish. Acute exposure affected renal development and inhibited the fluorescence of Na, K-ATPase alpha1A4:GFP zebrafish kidney. Chronic exposure influenced the body weight of both genders of adult fish and induced kidney damage by histopathological analyses. Furthermore, the exposure significantly disturbed differential expression genes (DEGs), diversity and richness of gut microbiota, and critical metabolites related to renal functions. The transcriptomic analysis revealed that kidney-related DEGs were linked with renal cell carcinoma, proximal tubule bicarbonate reclamation, calcium signaling pathway, and HIF-1 signaling pathway. The significantly disrupted intestinal microbiota was closely related to the environmental factors and H&E score, which demonstrated the mechanisms of kidney risks. Notably, the Spearman correlation analysis indicated that the changed bacteria such as Pseudomonas, Paracoccus, and ZOR0006, etc were significantly connected to the DEGs and metabolites. Therefore, the assessment of multiple environmental factors provided new insights on "bio-markers" as potential therapies of the target signaling pathways, metabolites, and gut bacteria to monitor or protect residents from CKDu.

Environmental melamine exposure and adverse kidney outcomes in patients with type 2 diabetes mellitus

The impact of melamine exposure on kidney outcomes in type 2 diabetes mellitus (T2D) patients remains unclear. In this prospective cohort study, 561 T2D patients during October 2016 and June 2020 were enrolled and followed until December 2021. Baseline one-spot urinary corrected melamine levels were measured by LC-MS/MS. Average daily intake (ADI) of melamine represented environmental melamine exposure in daily life, and was estimated using urinary corrected melamine level by creatinine excretion (CE)-based model. Primary kidney outcomes were defined as doubling of serum creatinine levels or end stage kidney disease (ESKD), and secondary kidney outcomes included rapid decline in kidney function as estimated glomerular filtration rate (eGFR) decline >5 ml/min/1.73 m²/year. Baseline median urinary corrected melamine levels and estimated DI of melamine were 0.8 μg/mmol and 0.3 μg/kg/day in 561 T2D patients. During 3.7 years of follow-up, urinary corrected melamine level was positively correlated with reaching composite outcomes of either doubling of serum creation levels or ESKD and rapid decline in kidney function. Those with the highest quartile of urinary corrected melamine had 2.96-fold risk of composite outcomes of either doubling of serum creation levels or ESKD and 2.47-fold risk of eGFR decline >5 ml/min/1.73 m²/year. Estimated ADI of melamine also had significant correlation with adverse kidney outcomes. Furthermore, the positive relationship between melamine exposure and rapid decline in kidney function was only found in T2D patients with male, baseline eGFR ≥60 ml/min/1.73 m² or glycated hemoglobin ≤7%. In conclusion, melamine exposure is significantly associated with adverse kidney outcomes in T2D patients, especially in those with male, well sugar control or good baseline kidney function.

Early Ultrastructural Changes in Biopsies From Patients With Symptomatic CKD of Uncertain Etiology

Introduction

Although the investigation of chronic kidney disease of uncertain etiology (CKDu) has identified many possible influencing factors in recent years, the exact pathomechanism of this disease remains unclear.

Methods

In this study, we collected 13 renal biopsies from patients with symptomatic CKDu (Sym-CKDu) from Sri Lanka with well-documented clinical and socioeconomic factors. We performed light microscopy and electron microscopic evaluation for ultrastructural analysis, which was compared with 100 biopsies from German patients with 20 different kidney diseases.

Results

Of the 13 Sri Lankan patients, 12 were men (92.3%), frequently employed in agriculture (50%), and experienced symptoms such as feeling feverish (83.3%), dysuria (83.3%), and arthralgia (66.6%). Light microscopic evaluation using activity and chronicity score revealed that cases represented early stages of CKDu except for 2 biopsies, which showed additional signs of diabetes. Most glomeruli showed only mild changes, such as podocyte foot process effacement on electron microscopy. We found a spectrum of early tubulointerstitial changes including partial loss of brush border in proximal tubules, detachment of tubular cells, enlarged vacuoles, and mitochondrial swelling associated with loss of cristae and dysmorphic lysosomes with electron-dense aggregates. None of these changes occurred exclusively in Sym-CKDu; however, they were significantly more frequent in these cases than in the control cohort.

Conclusion

In conclusion, our findings confirm the predominant and early alterations of tubular structure in CKDu that can occur without significant glomerular changes. The ultrastructural changes do not provide concrete evidence of the cause of CKDu but were significantly more frequent in Sym-CKDu than in the controls.

Factors Associated with Chronic Kidney Disease of Unknown Etiology (CKDu): A Systematic Review

(1) Background: Despite ample research, the factors, specific causes, and pathways associated with chronic kidney disease of unknown etiology (CKDu) remain elusive. Therefore, we performed a systematic review to explore the potential etiologies for the development of CKDu globally. (2) Methods: A systematic literature review was conducted using databases CINAHL, Cochrane Library, Embase, Google Scholar, MEDLINE, and PsycINFO on the specific causes and pathophysiology related to CKDu from inception until April 2021. Study selection, data extraction of included articles, and quality appraisal were assessed. The narrative approach was used to summarize and comprehend the findings. (3) Results: Our study included 25 studies, considering 38,351 participants. Twelve studies were case-control, ten were cross-sectional, and three were cohort designs. All articles were from low-and middle-income countries (LMICs). The findings suggest 12 factors are associated with CKDu. Most studies (n = 8) identified farming and water sources as the factors related to CKDu, with heavy metal toxicity coming in second (n = 7). (4) Conclusion: The systematic review reported various factors associated with CKDu, from which most studies reported farming, water sources, and heavy metal poisoning. Considering the findings, the study recommends future strategies and public health initiatives to prevent the epidemiological/environmental factors contributing to CKDu.

Slight Changes in the Gut Microbiome in Early-stage Chronic Kidney Disease of Unknown Etiology

Gut dysbiosis and changes in short-chain fatty acids (SCFAs) occur in end-stage chronic kidney disease (CKD); however, the degree of these changes in the gut microbiome and serum SCFA profiles in the early stages of CKD,‍ ‍particularly in‍ ‍CKD‍ ‍of unknown etiology (CKDu), is unclear. We herein investigated the gut microbiome and SCFA profiles of early-stage CKD patients (CKD stages 1-3) in a community in Khon Kaen Province, Thailand. Seventy-two parasite-free participants were distributed among a healthy control group (HC, n=18) and three patient groups (an underlying disease group [UD, n=18], early-stage CKD with underlying disease [CKD-UD, n=18], and early-stage CKD of unknown etiology, [CKDu, n=18]). Fecal DNA was individually extracted and pooled for groups of six individuals (three pools in each group) to examine the composition of the gut microbiome using next-generation sequencing. A SCFA ana-lysis was performed on serum samples from each individual using gas chromatography-mass spectrometry. The results revealed that microbial abundance differed between the healthy group and all patient groups (UD, CKD-UD, and CKDu). [Eubacterium]_coprostanoligenes_group was more abundant in the CKDu group than in the HC and CKD-UD groups. Furthermore, serum concentrations of acetate, a major SCFA component, were significantly lower in all patient groups than in the HC group. The present results indicate that minor changes in the gut microbiome and a significant decrease in serum acetate concentrations occur in early-stage CKDu, which may be important for the development of prevention strategies for CKD patients.

Hemoglobin Levels Among Male Agricultural Workers: Analyses From the Demographic and Health Surveys to Investigate a Marker for Chronic Kidney Disease of Uncertain Etiology

OBJECTIVE

Estimate agricultural work's effect on hemoglobin (Hgb) level in men. A negative effect may indicate presence of chronic kidney disease of uncertain etiology.

METHODS

We use Demographic and Health Surveys data from seven African and Asian countries and use matching to control for seven confounders.

RESULTS

On average, Hgb levels were 0.09 g/dL lower among agricultural workers compared with matched controls. Significant effects were observed in Ethiopia, India, Lesotho, and Senegal, with effects from 0.07 to 0.30 g/dL lower Hgb level among agricultural workers. The findings were robust to multiple control groups and a modest amount of unmeasured confounding.

CONCLUSIONS

Men engaged in agricultural work in four of the seven countries studied have modestly lower Hgb levels. Our data support integrating kidney function assessments within Demographic and Health Surveys and other population-based surveys.

'A disease of disparity': chronic kidney disease of unknown aetiology in endemic immigrant communities

Chronic kidney disease (CKD) of unknown aetiology is a form of tubulointerstitial CKD in the absence of traditional and known predisposing risk factors. Since the early 2000s, there is an emerging trend in marginalised agricultural communities among workers exposed to occupational and environmental hazards. CKD of unknown aetiology has received significant attention in recent years and is becoming increasingly relevant to the Australian medical community with the growing migrant population, which this case‐based communication illustrates.

Could Consumption of Trace Element-Contaminated Rice Be a Risk Factor for Acute Interstitial Nephritis with Uncertain Etiology in the Dry Zone of Sri Lanka?

Ingestion of toxic trace elements in the human body has been considered one of the major reasons for renal dysfunction. Chronic kidney disease with uncertain etiological factors (CKDu) is a recently described clinical entity in which the disease is found in geographically isolated pockets in the dry zone of Sri Lanka. In CKDu regions, an increasing number of cases are reported with acute interstitial nephritis without any known reason (AINu). However, recent exposure to certain risk behaviors or nephrotoxins, or both, is suspected for the AINu. Consumption of foods that are contaminated with trace elements is one of the main pathways of human exposure to environmental toxins. The current study was carried out to assess the possibility of trace element-contaminated rice consumption on the etiopathogenesis of AINu. Samples of rice consumed by 32 clinically diagnosed AINu cases were collected and analyzed for possible nephrotoxic trace elements. Out of 32 patients, 26 were histologically confirmed with tubulointerstitial disease. The results revealed that the mean values of Cd, As, and Pb were 0.18, 0.055, and 0.135 mg/kg, with ranges of 0.020-1.06, 0.012-0.222, and 0.003-0.744 mg/kg (on dry weight basis), respectively. This study indicated that the investigated toxic trace element levels of rice consumed by AINu were reasonably below the recommended levels of the Codex Alimentarius Commission of FAO and WHO. Hence, it is less likely that rice consumption is to be a risk factor for the etiology of AINu.

A review of molecular mechanisms linked to potential renal injury agents in tropical rural farming communities

The chronic kidney disease of unknown etiology (CKDu) is a global health concern primarily impacting tropical farming communities. Although the precise etiology is debated, CKDu is associated with environmental exposures including heat stress and chemical contaminants such as fluoride, heavy metals, and herbicide glyphosate. However, a comprehensive synthesis is lacking on molecular networks underpinning renal damage induced by these factors. Addressing this gap, here we present key molecular events associated with heat and chemical exposures. We identified that caspase activation and lipid peroxidation are common endpoints of glyphosate exposure, while vasopressin and polyol pathways are associated with heat stress and dehydration. Heavy metal exposure is shown to induce lipid peroxidation and endoplasmic reticulum stress from ROS activated MAPK, NFĸB, and caspase. Collectively, we identify that environmental exposure induced increased cellular oxidative stress as a common mechanism mediating renal cell inflammation, apoptosis, and necrosis, likely contributing to CKDu initiation and progression.

Potentials of ketogenic diet against chronic kidney diseases: pharmacological insights and therapeutic prospects

BACKGROUND

Chronic kidney disease (CKD) is a worldwide public health concern. Nutritional interventions become a primary concern in managing various diseases, including CKD. Ketogenic diets (KD) are a popular diet and an increasingly used diet for weight loss.

MAIN BODY

With the increasing cases of CKD, KD has been proposed as a treatment by many scientists. Several studies have shown that KD can slow down the progression rate of renal abnormalities. Also, this diet is regarded as a safe route for managing CKD. CKD is generally associated with increased inflammation, oxidative stress, fibrosis, autophagy dysfunction, and mitochondrial dysfunction, while all of these can be attenuated by KD. The protective effect of KD is mainly mediated through inhibition of ROS, NF-κB, and p62 signaling.

CONCLUSIONS

It is suggested that KD could be considered a new strategy for managing and treating CKD more carefully. This review explores the potential of KD on CKD and the mechanism involved in KD-mediated kidney protection.

Chronic kidney disease of unknown etiology in India: a comparative study with Mesoamerican and Sri Lankan nephropathy

Chronic kidney disease of unknown etiology [CKDu] is a condition characterized by decline in kidney function and is not associated with diabetic nephropathy or hypertensive nephropathy. In this review, we have done a detailed literature analysis on CKDu in India, and then had a comparison with that of Mesoamerica and Sri Lanka. In India, CKDu became the second most common type of CKD after diabetic nephropathy. Silica was seen in the groundwater of both India and Sri Lanka, whereas in Mesoamerica silica exposure through particulate matter was seen among CKDu communities. DDE is a common agrochemical seen in both India and Sri Lanka. The risk factors vary from region to region and it is important to categorize CKDu population based on the risk factors to avoid misinterpretation of the condition as non-CKDu category and to evade further complications. More studies have to be conducted to reveal the detailed pathophysiological mechanisms and its relation with irrational exploitation of environmental resources.

Sex and gender differences in chronic kidney disease and access to care around the globe

The difference between sex, the biological construct, and gender, the social construct, may be most evident in settings of vulnerability. Globally, chronic kidney disease is more prevalent among women, but the prevalence of end-stage kidney failure, and especially receipt of kidney replacement therapy, is higher in men. These differences likely reflect a combination of physiological and social/structural risk factors that independently modulate kidney disease and/or its progression. The distribution of the most common risk factors such as hypertension and obesity differ between men and women and may impact disease risk differentially. Social and structural gender-related inequities remain stark across the globe. More women live in poverty, receive less education, and are more dependent on others for health care decision making, but men may have a higher risk of injury, occupational exposures, and less access to screening, prevention, and primary care. In this article, we explore how social determinants of health affect kidney disease risk and access to care differentially across genders, and differently across the globe. We also describe specific challenges experienced by boys and girls with kidney disease, how culture and geography may impact kidney care in places where resources are particularly limited such as sub-Saharan Africa, and give examples of social and structural circumstances that place young men and women at high risk of kidney disease in Mexico and Central America, illustrated by case vignettes. The coronavirus disease-2019 pandemic has raised awareness of pervasive gender-based inequities within all societies. This applies to kidney disease and is not new. The nephrology community must add its voice to the calls for action, for a more just society overall, and for the recognition of the roles of sex and gender as modulators of kidney disease risk and access to care.

Multi-pronged research on endemic chronic kidney disease of unknown etiology in Sri Lanka: a systematic review

Increasing prevalence of endemic chronic kidney disease of unknown etiology (CKDu) in Sri Lanka is a major health problem since the 1990s. Despite numerous studies on CKDu, research groups have been unable to develop a comprehensive approach to mitigate the disorder, and thereby to identify research gaps. We conducted a systematic literature review of 119 publications on CKDu in Sri Lanka from Pubmed, Google Scholar, and Scopus, published until end September 2020. A higher CKDu prevalence in the working population of the North Central Province was reported with recent studies indicating patients from non-endemic regions as well. A majority were etiological studies that recorded conflicting and inconclusive evidence on CKDu etiology. Studies on clinico-pathological, diagnostic, biochemical, and molecular biological aspects of CKDu, studies analyzing CKDu symptom burden, anthropological, and behavioral impacts of CKDu, were reviewed as well. A dearth of research exists on nutritional, demographical, immunological, and microbial aspects of CKDu. The overview of the reviewed literature indicated the absence of a comprehensive plan of action to mitigate this situation. Hence, we propose the "One Health" approach with a systems dynamics model as a potential way forward to alleviate the CKDu epidemic in Sri Lanka. This enables the representation of multiple causative agents (and interactions thereof) among environmental, animal, and human systems, in concert with the "exposome" that provides the totality of exposure the individual has undergone since birth.

Increased labor losses and decreased adaptation potential in a warmer world

Working in hot and potentially humid conditions creates health and well-being risks that will increase as the planet warms. It has been proposed that workers could adapt to increasing temperatures by moving labor from midday to cooler hours. Here, we use reanalysis data to show that in the current climate approximately 30% of global heavy labor losses in the workday could be recovered by moving labor from the hottest hours of the day. However, we show that this particular workshift adaptation potential is lost at a rate of about 2% per degree of global warming as early morning heat exposure rises to unsafe levels for continuous work, with worker productivity losses accelerating under higher warming levels. These findings emphasize the importance of finding alternative adaptation mechanisms to keep workers safe, as well as the importance of limiting global warming.

Outdoor workers may need to adapt to warming by moving labor from midday to cooler hours. Here the authors find this adaptation strategy loses efficacy under additional climate change due to increased heat exposure in the coolest hours of the day.

Seasonal Variations in Groundwater Quality and Hydrogeochemistry in the Endemic Areas of Chronic Kidney Disease of Unknown Etiology (CKDu) in Sri Lanka

Groundwater quality and geochemical processes were investigated in the endemic areas of chronic kidney disease of unknown etiology (CKDu) in Sri Lanka. Representative groundwater samples (n = 60) were collected from 30 dug wells located in the Anuradhapura district, over the dry and wet seasons. The samples were analyzed for pH, electrical conductivity (EC), total dissolved solids (TDS), alkalinity, major cations and major anions. Calcium-magnesium-bicarbonate ion combinations are predominant in this groundwater, and the simultaneous occurrence of high hardness (382–394 mg/L as CaCO3), alkalinity (364–379 mg/L as CaCO3) and ionicity is a salient characteristic. Alkalinity, TDS, hardness, and magnesium exceeded the safe limits for drinking in over half of the samples, regardless of the season. The major ion chemistry (Ca2+, Mg2+, Na+ and HCO3−) is primarily governed by the weathering of carbonate and silicate minerals, ion exchange, and evaporation which is accelerated by the semi-arid climate. Fluoride and chloride inputs are regulated by dissolution of fluoride-bearing minerals and anthropogenic causes, respectively. Saturation indices suggested supersaturation of carbonates and silicates, and undersaturation of evaporites and fluorite. Persistent high ionicity, and hardness of groundwater that is seldom impacted by seasonal variations might be playing a vital role in the genesis of CKDu.

Chronic Kidney Disease of Unknown Etiology in India: What Do We Know and Where We Need to Go

Chronic kidney disease (CKD) not associated with known risk factors has been reported from parts of India and is presumed to be similar to CKD of unknown etiology (CKDu) that has been described from Central America. The reports from India have been fragmented without clear description of the disease phenotype or its determinants. This paper summarizes the current state of knowledge around CKDu in India based on a review of literature, multi-stakeholder consultation, and a survey of Indian nephrologists. We also contacted individual research groups to solicit data. Our findings suggest that that CKDu is reported from most regions in India; however, it is interpreted differently from the phenotype described from Central America and Sri Lanka. The differences include lack of a clear demographic or occupation group, older age of affected participants, and presence of mild hypertension and low-grade proteinuria. Well-designed prospective field studies with appropriate diagnostic workup are needed to establish the disease burden and identify etiologies, along with socioeconomic and health consequences, the intersection with the environment, and the public health response. Community-based research should phenotype the entire CKD population rather than be restricted to cases with presumed CKDu based on predefined criteria. Guidelines are needed for clinical evaluation, referral, management, and harmonization of clinical documentation and health records. More data are needed to support the existence of a unique CKDu phenotype in India.

Risk factors for endemic chronic kidney disease of unknown etiology in Sri Lanka: Retrospect of water security in the dry zone

The prevalence of chronic kidney disease of unknown etiology (CKDu) is receiving considerable attention due to the serious threat to human health throughout the world. However, the roles of geo-socio-environmental factors in the prevalence of the CKDu endemic areas are still unknown. Sri Lanka is one of the countries most seriously affected by CKDu, where 10 out of 25 districts have been identified as the areas with the high prevalence of CKDu (10-20%). This review summarizes the geographical distribution of CKDu and its probable geochemical, behavioral, sociological, and environmental risk factors based on research related to hydrogeochemical influences on CKDu in Sri Lanka. More than 98% of CKDu patients have consumed groundwater as their primary water source in daily life, indicating the interactions of geogenic contaminants (such as F^-, total dissolved solids, Hofmeister ions) in groundwater is responsible for the disease. Apart from the hydrogeochemical factors, mycotoxins, cyanotoxins, use of some herbal medicines, dehydration, and exposure to agrochemicals were alleged as risk factors. Sociological factors, including poverty, living habits and anthropogenic activities, may also provoke the emergence of CKDu. Therefore, the interaction of geo-socio environmental risk factors should be sociologically and scientifically considered to prevent the prevalence of CKDu. Future in-depth studies are required to reveal the individual role of each of the postulated etiological factors, possibly using machine learning and advanced statistics.

Aguascalientes: one of the hottest chronic kidney disease (CKD) hotspots in Mexico and a CKD of unknown aetiology mystery to be solved

In a recent issue of Clinical Kidney Journal (CKJ), Gutierrez-Peña et al. reported a high incidence and prevalence of advanced chronic kidney disease (CKD) in Aguascalientes, Mexico. This contradicts Global Burden of Disease estimates, which should be updated. A key component of this high burden of CKD relates to young people ages 20-40 years in whom the cause of CKD was unknown [CKD of unknown aetiology (CKDu)]. The incidence of kidney replacement therapy in this age group in Aguascalientes is among the highest in the world, second only to Taiwan. However, high-altitude Aguascalientes, with a year-round average temperature of 19°C, does not fit the geography of other CKDu hotspots. Furthermore, kidney biopsies in young people showed a high prevalence of focal segmental glomerulosclerosis. Potential causes of CKDu in Aguascalientes include the genetic background (no evidence, although podocytopathy genes should be explored) and environmental factors. The highest prevalence of CKD was found in Calvillo, known for guava farming. Thus guava itself, known to contain bioactive, potentially nephrotoxic molecules and pesticides, should be explored. Additionally, there are reports of water sources in Aguascalientes contaminated with heavy metals and/or pesticides. These include fluoride (increased levels found in Calvillo drinking water) as well as naturally occurring arsenic, among others. Fluoride may accumulate in bone and cause kidney disease years later, and maternal exposure to excess fluoride may cause kidney disease in offspring. We propose a research agenda to clarify the cause of CKDu in Aguascalientes that should involve international funders. The need for urgent action to identify and stem the cause of the high incidence of CKD extends to other CKD hotspots in Mexico, including Tierra Blanca in Veracruz and Poncitlan in Jalisco.

Women and other risk factors for chronic kidney disease of unknown etiology in Thailand: National Health Examination V Survey

There are limited data on chronic kidney disease of unknown etiology (CKDu) from Southeast Asia. Initially described in working age men, a common approach to detect CKDu that includes all adults has recently been proposed. We determined the prevalence, and risk factors for CKDu using data from a cross-sectional, nationally representative survey of the adult population of Thailand. We used a proxy for CKDu as age < 70 with impaired kidney function (eGFR < 60) in the absence of diabetes and hypertension (CKDu1) and heavy proteinuria (CKDu2). Prevalence estimates were probability-weighted for the Thai population. The associations between risk factors and CKDu or elderly subjects with eGFR < 60 without traditional causes were assessed by multivariable logistic regression. Of 17,329 subjects, the prevalence were: eGFR < 60, 5.3%; CKDu1 0.78%; CKDu2, 0.75%. CKDu differed by 4.3-folds between regions. Women, farmers/laborers, older age, gout, painkillers, rural area, and stones were independent risk factors for CKDu. Women, age, rural, gout, painkillers were significant risk factors for both CKDu and elderly subjects. These data collected using standardized methodology showed that the prevalence of CKDu in Thailand was low overall, although some regions had higher risk. Unlike other countries, Thai women had a two-fold higher risk of CKDu.

Proteomic profile of mesothelial exosomes isolated from peritoneal dialysis effluent of children with focal segmental glomerulosclerosis

Peritoneal dialysis (PD) is the worldwide recognized preferred dialysis treatment for children affected by end-stage kidney disease (ESKD). However, due to the unphysiological composition of PD fluids, the peritoneal membrane (PM) of these patients may undergo structural and functional alterations, which may cause fibrosis. Several factors may accelerate this process and primary kidney disease may have a causative role. In particular, patients affected by steroid resistant primary focal segmental glomerulosclerosis, a rare glomerular disease leading to nephrotic syndrome and ESKD, seem more prone to develop peritoneal fibrosis. The mechanism causing this predisposition is still unrecognized. To better define this condition, we carried out, for the first time, a new comprehensive comparative proteomic mass spectrometry analysis of mesothelial exosomes from peritoneal dialysis effluent (PDE) of 6 pediatric patients with focal segmental glomerular sclerosis (FSGS) versus 6 patients affected by other primary renal diseases (No FSGS). Our omic study demonstrated that, despite the high overlap in the protein milieu between the two study groups, machine learning allowed to identify a core list of 40 proteins, with ANXA13 as most promising potential biomarker, to distinguish, in our patient population, peritoneal dialysis effluent exosomes of FSGS from No FSGS patients (with 100% accuracy). Additionally, the Weight Gene Co-expression Network Analysis algorithm identified 17 proteins, with PTP4A1 as the most statistically significant biomarker associated to PD vintage and decreased PM function. Altogether, our data suggest that mesothelial cells of FSGS patients are more prone to activate a pro-fibrotic machinery. The role of the proposed biomarkers in the PM pathology deserves further investigation. Our results need further investigations in a larger population to corroborate these findings and investigate a possible increased risk of PM loss of function or development of encapsulating peritoneal sclerosis in FSGS patients, thus to eventually carry out changes in PD treatment and management or implement new solutions.

Environment and chronic kidney disease in farmers

The prevalence of chronic kidney disease (CKD) has been on the rise worldwide. Epidemiological studies performed primarily in Central America and South Asia have reported high prevalence of CKD among young and middle-aged men working in agricultural communities. The clinical features do not appear linked to any classical CKD risk factors, such as hypertension, diabetes, or chronic nephritis. The disease develops and progresses as interstitial nephritis, without showing noticeable symptoms or high levels of proteinuria. Pathologically, the disease essentially represents chronic interstitial nephritis and is termed chronic interstitial nephritis in agricultural communities (CINAC). The potential causes of CINAC include: (1) heat stress-related factors associated with increased ambient temperatures resulting from global warming; and (2) factors connected with exposure to agrochemicals and/or pesticides. Global warming and environmental pollution will undoubtedly pose a significant health risk to farmers, and heat stress during farm work could easily result in the development and progression of CKD. Japanese agricultural regions evidently will not be spared from global environmental changes. For future epidemiological studies, researchers should establish a more comprehensive analytical method that can incorporate additional risk-factor variables, such as occupational history (including agricultural work) and ambient temperature.

Natural and Anthropogenic Controls of Groundwater Quality in Sri Lanka: Implications for Chronic Kidney Disease of Unknown Etiology (CKDu)

Poor groundwater quality in household wells is hypothesized as being a potential contributor to chronic kidney disease of unknown etiology (CKDu) in Sri Lanka. However, the influencing factors of groundwater quality in Sri Lanka are rarely investigated at a national scale. Here, the spatial characteristics of groundwater geochemistry in Sri Lanka were described. The relationships of groundwater quality parameters with environmental factors, including lithology, land use, and climatic conditions, were further examined to identify the natural and anthropogenic controlling factors of groundwater quality in Sri Lanka. The results showed that groundwater geochemistry in Sri Lanka exhibited significant spatial heterogeneity. The high concentrations of NO3− were found in the districts that have a higher percentage of agricultural lands, especially in the regions in the coastal zone. Higher hardness and fluoride in groundwater were mainly observed in the dry zone. The concentrations of trace elements such as Cd, Pb, Cu, and Cr of all the samples were lower than the World Health Organization guideline values, while some the samples had higher As and Al concentrations above the guideline values. Principal component analysis identified four components that explained 73.2% of the total data variance, and the first component with high loadings of NO3−, hardness, As, and Cr suggested the effects of agricultural activities, while other components were primarily attributed to natural sources and processes. Further analyses found that water hardness, fluoride and As concentration had positive correlations with precipitation and negative correlations with air temperature. The concentration of NO3− and water hardness were positively correlated with agricultural lands, while As concentration was positively correlated with unconsolidated sediments. The environmental factors can account for 58% of the spatial variation in the overall groundwater geochemistry indicated by the results of redundancy analysis. The groundwater quality data in this study cannot identify whether groundwater quality is related to the occurrence of CKDu. However, these findings identify the coupled controls of lithology, land use, and climate on groundwater quality in Sri Lanka. Future research should be effectively designed to clarify the synergistic effect of different chemical constituents on CKDu.

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.

Chronic Kidney Disease of Unknown Origin: A Mysterious Epidemic

Amongst the many threats to health in our world, the most challenging ones are the ones with unknown causes. There is a mysterious epidemic of kidney disease called chronic kidney disease of unknown etiology (CKDu) that is occurring in many parts of the world. Unrelated to known risk factors such as diabetes and hypertension, CKDu mostly affects the young and middle-aged, with slight preponderance in males. It mostly occurs in people living in rural areas, especially working in agricultural jobs. Worldwide, the number of people with chronic kidney disease, and those who need dialysis and renal replacement, is increasing every year as compared to other chronic conditions like diabetes and AIDS. It's not just alarming but a great challenge to healthcare systems across the world, especially in resource-poor countries. CKDu has become a silent killer for most patients. The occurrence of end-stage renal disease (ESRD) in CKDu can be catastrophic for individuals, especially in countries with limited medical facilities, causing a significant socio-economic burden. Even within these economically developing nations, people affected by CKDu usually are from the most vulnerable and underserved populations. As a definitive etiology has not been postulated for CKDu to date, this comprehensive review was undertaken to throw light on the poorly understood epidemiologic risk factors and the course of the disease.

Chronic kidney disease of unknown origin is associated with environmental urbanisation in Belfast, UK

Chronic kidney disease (CKD), a collective term for many causes of progressive renal failure, is increasing worldwide due to ageing, obesity and diabetes. However, these factors cannot explain the many environmental clusters of renal disease that are known to occur globally. This study uses data from the UK Renal Registry (UKRR) including CKD of uncertain aetiology (CKDu) to investigate environmental factors in Belfast, UK. Urbanisation has been reported to have an increasing impact on soils. Using an urban soil geochemistry database of elemental concentrations of potentially toxic elements (PTEs), we investigated the association of the standardised incidence rates (SIRs) of both CKD and CKD of uncertain aetiology (CKDu) with environmental factors (PTEs), controlling for social deprivation. A compositional data analysis approach was used through balances (a special class of log contrasts) to identify elemental balances associated with CKDu. A statistically significant relationship was observed between CKD with the social deprivation measures of employment, income and education (significance levels of 0.001, 0.01 and 0.001, respectively), which have been used as a proxy for socio-economic factors such as smoking. Using three alternative regression methods (linear, generalised linear and Tweedie models), the elemental balances of Cr/Ni and As/Mo were found to produce the largest correlation with CKDu. Geogenic and atmospheric pollution deposition, traffic and brake wear emissions have been cited as sources for these PTEs which have been linked to kidney damage. This research, thus, sheds light on the increasing global burden of CKD and, in particular, the environmental and anthropogenic factors that may be linked to CKDu, particularly environmental PTEs linked to urbanisation.

Groundwater as a potential cause of Chronic Kidney Disease of unknown etiology (CKDu) in Sri Lanka: a review

The cause of Chronic Kidney Disease of unknown etiology (CKDu) in the rural dry zone of Sri Lanka remains unidentified, despite vast research efforts that brought about an extensive list of potential risk factors. Among these, the long-term exposure to various nephrotoxic elements through drinking groundwater was widely suspected owing to the unique geographical distribution of the disease. This review focuses on such well-known hypotheses suspecting the relations with fluoride, hardness, major ions, heavy metals, metalloids, organic matter, agrochemical residues, pathogens, and bacterial toxins in the groundwaters of the CKDu-endemic region. It was comprehensively discussed why each of these constituents was considered a risk factor of CKDu, how could they possibly trigger the pathogenesis of the disease, what was the evidence that supported or failed each hypothesis, and whether providing safe drinking water had been effective at mitigating the progression of the disease. Although plenty of circumstantial evidence supported an etiology related to groundwater for CKDu, it was impossible to elucidate the cause-effect relationships between drinking impaired groundwater and the occurrence of the disease. Future research should be effectively designed to clarify the role of groundwater in the onset of CKDu by taking into account the gaps in past research.

A Systematic Review of Renal Pathology in Chronic Kidney Disease of Uncertain Etiology

INTRODUCTION

Despite much research on chronic kidney disease of uncertain etiology (CKDu) in Sri Lanka and the Mesoamerican nephropathy, the etiology and pathogenesis of this disease remains elusive. The pathology has broadly been described as chronic tubulointerstitial nephritis and no specific signature lesions have been identified.

METHODS

A scoping review was conducted through MEDLINE and Google Scholar databases for peer-reviewed publications on biopsy studies related to CKDu - Sri Lanka and Mesoamerican nephropathy to develop a comparative and critical analysis of the renal pathology found in these patients.

RESULTS

Thirteen studies met the selection criteria. Interstitial fibrosis was the predominant lesion in all the studies. Tubulointerstitial and glomerular abnormalities showed a more variable distribution. No characteristic histopathological feature was reported other than a proximal tubular lysosomal inclusion body which was claimed to indicate a toxic etiology. Three main pathogenetic mechanisms were postulated: repeated acute insults leading to scarring, low-grade chronic insults leading to non-inflammatory fibrosis, and tubulointerstitial damage in combination with glomerular injury. The main limitations in the interpretation and comparative analysis of these studies were the heterogeneity in case selection and biopsy reporting.

CONCLUSIONS

Although no characteristic histopathological feature could be found in CKDu-Sri Lanka or Mesoamerican nephropathy, there are noticeable differences between these two groups in the frequency and severity of the glomerular and tubulointerstitial changes which warrant more explorative studies preferably on kidneys in early stages of the disease. Future strategies should ensure that more uniform selection criteria and reporting methods are used.

Correlation of Kidney Size on Computed Tomography with GFR, Creatinine and HbA1C for an Accurate Diagnosis of Patients with Diabetes and/or Chronic Kidney Disease

Diabetes is considered one of the major causes of chronic kidney disease (CKD), affecting renal blood vessels and nerves. Diagnosis of CKD by traditional biochemical serum and blood analyses is insufficient and insensitive, thus requiring the development of a more robust technique. This novel study aims to propose a new method for the accurate diagnosis of CKD, quantification of kidney damage, and its prognosis by physicians by measuring the kidney volume on computed tomography (CT). In total, 251 patients were enrolled in this retrospective study. They were divided into four groups: control, patients having diabetes, patients having CKD, and patients having both diabetes and CKD. Results showed that kidney volume correlated negatively with both GFR and HbA1C on CT images, in addition to decreasing faster in males than females. Moreover, HbA1C was shown to correlate positively with creatinine and negatively with GFR. Finally, GFR was more robust than creatinine when correlated with age. The association between kidney volume with GFR and HbA1c can be used to accurately anticipate kidney volume in established CKD on CT scan, especially in resource-poor settings. Furthermore, HbA1C can serve as a powerful biomarker for studying renal function in diabetic CKD patients as it correlates with creatinine and GFR.

Chronic interstitial nephritis in agricultural communities: a new perspective on etiology, diagnosis and mechanism

Chronic interstitial nephritis in agricultural communities is a devastating kidney disease with a globally increasing prevalence. Its cause is unknown. Two predominant etiologies are hypothesised: recurrent episodes of dehydration and exposure to environmental toxins, such as agrochemicals and metals. In this review, we summarise arguments on: 1) why heat stress/dehydration is an unlikely cause of this disease and 2) why chronic interstitial nephritis in agricultural communities is to be considered a toxin-induced nephropathy. Mechanistically, we provide arguments for a putative role of pesticides on the one hand, and the calcineurin pathway on the other hand, both of which require further investigation. Finally, we summarise several important perspectives for research on chronic interstitial nephritis in agricultural communities.

Extreme Weather and Climate Change: Population Health and Health System Implications

Extreme weather and climate events, such as heat waves, cyclones, and floods, are an expression of climate variability. These events and events influenced by climate change, such as wildfires, continue to cause significant human morbidity and mortality and adversely affect mental health and well-being. Although adverse health impacts from extreme events declined over the past few decades, climate change and more people moving into harm's way could alter this trend. Long-term changes to Earth's energy balance are increasing the frequency and intensity of many extreme events and the probability of compound events, with trends projected to accelerate under certain greenhouse gas emissions scenarios. While most of these events cannot be completely avoided, many of the health risks could be prevented through building climate-resilient health systems with improved risk reduction, preparation, response, and recovery. Conducting vulnerability and adaptation assessments and developing health system adaptation plans can identify priority actions to effectively reduce risks, such as disaster risk management and more resilient infrastructure. The risks are urgent, so action is needed now.

Environmental Health Threats to Latino Migrant Farmworkers

Approximately 75% of farmworkers in the United States are Latino migrants, and about 50% of hired farmworkers do not have authorization to work in the United States. Farmworkers face numerous chemical, physical, and biological threats to their health. The adverse effects of these hazards may be amplified among Latino migrant farmworkers, who are concurrently exposed to various psychosocial stressors. Factors such as documentation status, potential lack of authorization to work in the United States, and language and cultural barriers may also prevent Latino migrants from accessing federal aid, legal assistance, and health programs. These environmental, occupational, and social hazards may further exacerbate existing health disparities among US Latinos. This population is also likely to be disproportionately impacted by emerging threats, including climate change and severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). Latino migrant farmworkers are essential to agriculture in the United States, and actions are needed to protect this vulnerable population.

Transcriptomic signatures of exacerbated progression in leptospirosis subclinical chronic kidney disease with secondary nephrotoxic injury

High-incidence regions of leptospirosis caused by Leptospira spp. coincide with chronic kidney disease. This study investigated whether asymptomatic leptospirosis is an emerging culprit that predisposes to progressive chronic kidney disease when superimposed on secondary nephrotoxic injury. Kidney histology/function and whole transcriptomic profiles were evaluated for Leptospira-infected C57/BL6 mice with adenine-induced kidney injury. The extent of tubulointerstitial kidney lesions and expression of inflammation/fibrosis genes in infected mice with low-dose (0.1%) adenine, particularly in high-dose (0.2%) adenine-fed superimposed on Leptospira-infected mice, were significantly increased compared with mice following infection or adenine diet alone, and the findings are consistent with renal transcriptome analysis. Pathway enrichment findings showed that integrin-β- and fibronectin-encoding genes had distinct expression within the integrin-linked kinase-signaling pathway, which were upregulated in 0.2% adenine-fed Leptospira-infected mice but not in 0.2% adenine-fed mice, indicating that background subclinical Leptospiral infection indeed enhanced subsequent secondary nephrotoxic kidney injury and potential pathogenic molecules associated with secondary nephrotoxic leptospirosis. Comparative analysis of gene expression patterns with unilateral ureteric obstruction-induced mouse renal fibrosis and patients with chronic kidney disease showed that differentially expressed orthologous genes such as hemoglobin-α₂, PDZ-binding kinase, and DNA topoisomerase II-α were identified in infected mice fed with low-dose and high-dose adenine, respectively, revealing differentially expressed signatures identical to those found in the datasets and may serve as markers of aggravated kidney progression. This study indicates that background subclinical leptospirosis, when subjected to various degrees of subsequent secondary nephrotoxic injury, may predispose to exacerbated fibrosis, mimicking the pathophysiological process of progressive chronic kidney disease.NEW & NOTEWORTHY Leptospira-infected mice followed by secondary nephrotoxic injury exacerbated immune/inflammatory responses and renal fibrosis. Comparison with the murine model revealed candidates involved in the progression of renal fibrosis in chronic kidney disease (CKD). Comparative transcriptome study suggests that secondary nephrotoxic injury in Leptospira-infected mice recapitulates the gene expression signatures found in CKD patients. This study indicates that secondary nephrotoxic injury may exacerbate CKD in chronic Leptospira infection implicating in the progression of CKD of unknown etiology.

Pilot study determining the feasibility of implementing the Disadvantaged Populations eGFR Epidemiology Study (DEGREE) protocol, point-of-care field measurements and a new module on risk factors for chronic kidney disease of unknown origin in Hispanic outdoor workers

BACKGROUND

To field test the Disadvantaged Populations eGFR Epidemiology (DEGREE) protocol, outdoor point-of-care (POC) testing for serum creatinine, and a new risk factor module on chronic kidney disease of undetermined origin (CKDu) in U.S. outdoor Hispanic workers.

METHODS

Fifty workers were interviewed in Houston (TX). DEGREE and CKDu questionnaires were completed indoors. Anthropometrics and paired blood samples for POC and laboratory assay were completed outdoors over two periods (November-December 2017, April-May 2018).

RESULTS

Administration of DEGREE and CKDu questionnaires averaged 10 and 5 min, respectively, with all questions easily understood. We observed high correlations between POC and IDMS creatinine (r = 0.919) and BUN (r = 0.974). The POC device would disable testing when outdoor temperatures were above 85 °F or below 65 °F; this was adjustable.

CONCLUSIONS

Implementation of DEGREE and the new CKDu module was straightforward and well understood. The POC device performed well in the field, with some adjustment in methods when temperature readings were out of range.

A pilot case-control study using a one health approach to evaluate behavioral, environmental, and occupational risk factors for chronic kidney disease of unknown etiology in Sri Lanka

BACKGROUND

Chronic kidney disease of unknown etiology (CKDu) was first recognized in Sri Lanka in the early 1990s, and since then it has reached epidemic levels in the North Central Province of the country. The prevalence of CKDu is reportedly highest among communities that engage in chena and paddy farming, which is most often practiced in the dry zone including the North Central and East Central Provinces of Sri Lanka. Previous studies have suggested varied hypotheses for the etiology of CKDu; however, there is not yet a consensus on the primary risk factors, possibly due to disparate study designs, sample populations, and methodologies.

METHODS

The goal of this pilot case-control study was to evaluate the relationships between key demographic, cultural, and occupational variables as risk factors for CKDu, with a primary interest in pesticide exposure both occupationally and through its potential use as an ingredient in brewed kasippu alcohol. An extensive one health focused survey was developed with in cooperation with the Centre for Research, Education, and Training on Kidney Diseases of Sri Lanka.

RESULTS

A total of 56 CKDu cases and 54 control individuals were surveyed using a proctored, self-reported questionnaire. Occupational pesticide exposure and alcohol consumption were not found to be significant risk factors for CKDu. However, a statistically significant association with CKDu was observed with chewing betel (adjusted odds ratio [aOR]: 6.11, 95% confidence interval [CI]: 1.93, 19.35), age (aOR: 1.07, 95% CI: 1.02, 1.13), owning a pet dog (aOR: 3.74, 95% CI: 1.38, 10.11), water treatment (aOR: 3.68, 95% CI: 1.09, 12.43) and pests in the house (aOR: 5.81, 95% CI: 1.56, 21.60).

CONCLUSIONS

The findings of this study suggest future research should focus on practices associated with chewing betel, potential animal interactions including pests in the home and pets, and risk factors associated with water.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1186/s42522-020-00034-3.

Demystifying Chronic Kidney Disease of Unknown Etiology (CKDu): Computational Interaction Analysis of Pesticides and Metabolites with Vital Renal Enzymes

Chronic kidney disease of unknown etiology (CKDu) has been recognized as a global non-communicable health issue. There are many proposed risk factors for CKDu and the exact reason is yet to be discovered. Understanding the inhibition or manipulation of vital renal enzymes by pesticides can play a key role in understanding the link between CKDu and pesticides. Even though it is very important to take metabolites into account when investigating the relationship between CKDu and pesticides, there is a lack of insight regarding the effects of pesticide metabolites towards CKDu. In this study, a computational approach was used to study the effects of pesticide metabolites on CKDu. Further, interactions of selected pesticides and their metabolites with renal enzymes were studied using molecular docking and molecular dynamics simulation studies. It was evident that some pesticides and metabolites have affinity to bind at the active site or at regulatory sites of considered renal enzymes. Another important discovery was the potential of some metabolites to have higher binding interactions with considered renal enzymes compared to the parent pesticides. These findings raise the question of whether pesticide metabolites may be a main risk factor towards CKDu.

High prevalence of end-stage renal disease of unknown origin in Aguascalientes Mexico: role of the registry of chronic kidney disease and renal biopsy in its approach and future directions

Background

Chronic kidney disease (CKD) is one of the pathologies with the greatest impact on the public health system. Over the last few decades, the relevance of CKD in Mexico has increased, with associated overwhelming costs for care of renal disease. There are no reliable CKD statistics in Mexico.

Methodology

In June 2018, the government of Aguascalientes called on all Health Institutions to create a state registry of treated end-stage renal disease (ESRD). In the same system, a renal biopsy result registry included all the native kidney biopsies obtained in the state of Aguascalientes since 2012. We herein describe the prevalence, incidence and characteristics of the patients included in the CKD and renal biopsy registry in the state of Aguascalientes.

Results

As of April 2020, the state has documented 2827 patients on renal replacement therapy (RRT), 1877 on dialysis and 950 that have been transplanted. The prevalence of patients on dialysis is 1326 per million population (p.m.p.), and if transplanted individuals are included, it is 1997 p.m.p. The incidence of treated ESRD in 2019 was 336 p.m.p. (n = 474) in individuals with an average age of 45.6 years (standard deviation ±18), and in a higher proportion of men (61%). There is a bimodal distribution of the age at which RRT was initiated. The first and the most significant peaks are between the ages of 20 and 40 years and are usually the result of CKD of unknown cause (73%). The second peak is between 50 and 70 years of age, and CKD is usually the result of diabetes mellitus and systemic arterial hypertension (59.6%). Since January 2012, 423 biopsies have been recorded. The patient’s ages were between 20 and 30 years (n = 112), and the most frequent diagnosis was focal segmental glomerulosclerosis (FSGS) (54%).

Conclusions

The prevalence of treated ESRD in the state of Aguascalientes is high. The disease mostly afflicts young people between 20 and 40 years of age, and there is a clear male predominance. In this age group, the main clinical diagnosis is CKD of unknown origin, and the most frequent biopsy diagnosis was FSGS.

A comparative review: Chronic Kidney Disease of unknown etiology (CKDu) research conducted in Latin America versus Asia

INTRODUCTION

The incidence of chronic kidney disease of unknown or uncertain etiology (CKDu) is recognized as a global non-communicable health crisis. The goal of this work is to compare the types of research studies in Latin America and Asia, two regions with increasing CKDu incidence.

METHODS

A comparative literature review was conducted to evaluate the CKDu research design for peer-reviewed articles published from 2015 to 2019. Full texts were reviewed to identify study location, study type, study design, risk factors evaluated, and if applicable, sample type and number.

RESULTS

In Asia and Latin America, 82 and 65 articles were identified in total, respectively, with 55 field studies in Asia versus 34 in Latin America. In Asia, research was focused on drinking water (34), heavy metals (20), and agrochemical product usage (19) as potential risk factors. In Latin America, research focused mostly on heat stress/dehydration (36) and agrochemical product usage (18) as potential CKDu risk factors. Biological samples were collected more frequently than environmental samples, especially in Latin America.

DISCUSSION

Research to pinpoint the risk factors associated with CKDu to date is not standardized and typically limited in geographical scope. The emphasis of CKDu research varies by geographic region, with a greater priority placed on water quality and chemical exposure in Asia, versus dehydration and heat stress in Latin America. Using a harmonized approach to CKDu research would yield improved understanding of the risk factors associated with CKDu and how they compare across affected regions.

The Utility of Novel Renal Biomarkers in Assessment of Chronic Kidney Disease of Unknown Etiology (CKDu): A Review

Chronic Kidney Disease (CKD) is a globally prevalent non-communicable disease with significant mortality and morbidity. It is typically associated with diabetes and hypertension; however, over the last two decades, an emergence of CKD of unknown etiology (CKDu) has claimed thousands of lives in several tropical agricultural communities. CKDu is associated with gradual loss of renal function without initial symptoms until reaching complete kidney failure and eventually death. The most impacted are young adult males of lower socio-economic strata. Since the disease progression can be successfully attenuated through early detection, the development of superior screening and management measures is of utmost importance. In contrast to the conventional biomarkers, novel biomarkers with improved sensitivity and specificity are being discussed as promising tools for early diagnosis of the disease. This review summarizes emerging novel biomarkers used in assessing CKD and discusses the current utility and diagnostic potential of such biomarkers for CKDu screening in clinical settings of different communities impacted by CKDu. Our goal is to provide a framework for practitioners in CKDu impacted regions to consider the use of these novel biomarkers through this synthesis. The increased use of these biomarkers will not only help to validate their diagnostic power further and establish potential prognostic value but may also provide critical insights into sites and mechanisms of renal damage.

Chronic interstitial nephritis in agricultural communities (CINAC) and lysosomal tubulopathy: Is there a place for anti-oxidants?

Chronic Interstitial Nephritis in Agricultural Communities (CINAC) continues to attract controversy in the scientific community. It was previously known as Chronic Kidney Disease of Unknown Etiology (CKDu) and is not associated with the common aetiological factors such as diabetes. There is general acceptance that it is an environmentally induced disorder due to a combination of toxicities: heavy metals from food, fluoride in drinking water, hard water, heat stress and pesticides. The recent findings of a lysosomal inclusion body tubulopathy is of great interest to those attempting to find therapeutic agents to slow or eliminate its renal damage. The paper argues that despite these new findings, oxidative stress could play a key role and proposes that anti-oxidants such as Vitamin C and E be repurposed for treatment.

Association of Hantavirus Infections and Leptospirosis With the Occurrence of Chronic Kidney Disease of Uncertain Etiology in the North Central Province of Sri Lanka: A Prospective Study With Patients and Healthy Persons

Chronic Kidney disease of uncertain etiology (CKDu) has become a significant disease burden, affecting farming community of Sri Lanka and the exact etiology, which could be multifactorial, is not hitherto established. This study is aimed to determine the association of past hantavirus infection and leptospirosis with the occurrence of CKDu. A cohort (n = 179) of known CKDu patients living in high-CKDu prevalent areas of Anuradhapura district of Sri Lanka was compared with a group of 49 healthy, sex-matched younger blood relatives of CKDu patients (control-1) and another 48 healthy, age, and sex-matched individuals living in low-CKDu prevalent area (control-2) of the same district where same life style and climate conditions prevail. Fifty out of 179 (27.9%) CKDu patients, 16/49 (32.7%) of control-1 and 7/48 (14.6%) of control-2 were found positive for IgG antibodies to Puumala, Hantaan or both strains of hantaviruses. Hantaan strain specificity was found to be predominant in all study groups. Hantavirus IgG sero-prevalence of healthy individuals living in low-CKDu prevalent area was significantly lower compared to CKDu patients and healthy younger blood relatives living in high-CKDu prevalent areas (p = 0.03). Past hantavirus infection possesses a significant risk for the occurrence of CKDu (OR = 4.5; 95% CI-3.1-5.4, p = 0.02). In contrast, IgG seroprevalence to hantaviruses was not significantly different in CKDu patients and healthy younger blood relatives living in high-CKDu prevalent areas indicating past hantavirus infection has no association with the occurrence of CKDu or possibly, younger relatives may develop CKDu in subsequent years. Seroprevalence to leptospirosis showed no significant difference between CKDu patients and healthy controls.