Nephritis In Agricultural Communities Research Articles

Systematic Review of Kidney Injury Biomarkers for the Evaluation of CKD of Uncertain Etiology

IntroductionChronic kidney disease of uncertain etiology (CKDu) is an incompletely defined phenotype of CKD affecting young individuals mostly in agricultural communities in Central America and South Asia. CKDu is a diagnosis of exclusion made in individuals from endemic regions. MethodsWe conducted a systematic review of the primary literature on urinary and plasma kidney injury biomarkers measured in the setting of CKDu (through February 2023). Literature was identified via a Web of Science search and hand search of the references of previously identified literature. Search terms included “CKDu,” “Mesoamerican Nephropathy,” “CKD of unknown etiology,” “Chronic Interstitial Nephritis in Agricultural Communities,” “biomarker,” “urin*,” and/or “plasma.” ResultsA total of 25 papers were included. The two most frequently measured biomarkers were urinary kidney injury molecule-1 and urinary neutrophil gelatinase-associated lipocalin. There was substantial variability in study design, laboratory assay methods, and statistical methodology which prohibited meta-analysis. ConclusionBiomarkers that identify tubulointerstitial disease early and accurately may substantially accelerate progress in the study of CKDu and facilitate public health approaches that eventually lead to its prevention and elimination. To date, the literature is limited by relatively small sample sizes and methodological limitations which should be addressed in future studies.

Chronic Interstitial Nephritis in Agricultural Communities

Chronic Interstitial Nephritis in Agricultural Communities

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.

Chronic Interstitial Nephritis in Agricultural Communities: Observational and Mechanistic Evidence Supporting the Role of Nephrotoxic Agrochemicals.

Chronic interstitial nephritis in agricultural communities (CINAC) is an epidemic of kidney disease affecting specific tropical and subtropical regions worldwide and is characterized by progressive CKD in the absence of traditional risk factors, such as hypertension and diabetes. CINAC prevalence is higher among young, male agricultural workers, but it also affects women, children, and nonagricultural workers in affected areas. Biopsies from patients with CINAC across regions commonly demonstrate tubular injury with lysosomal aggregates, tubulointerstitial inflammation, and fibrosis and variable glomerular changes. Each endemic area holds environmental risk factors and patient/genetic milieus, resulting in uncertainty about the cause(s) of the disease. Currently, there is no specific treatment available for CINAC. We highlight survey findings of Houston-based migrant workers with CINAC and draw similarities between kidney injury phenotype of patients with CINAC and mice treated chronically with paraquat, an herbicide used worldwide. We propose potential pathways and mechanisms for kidney injury in patients with CINAC, which may offer clues for potential therapies.

Chronic Tubulointerstitial Nephropathy of Agricultural Communities

Chronic interstitial nephritis in agricultural communities is an emerging public health concern affecting numerous agricultural communities in tropical countries, including regions in India, with a significant impact on the health and well-being of affected individuals. The affected individuals suffer from various psychosocial, nutritional, and metabolic challenges due to organ failure, which affects their quality of life. The etiology remains poorly understood, and various risk factors, which include various environmental and occupational hazards, have been implicated in its development. The recent discovery of lysosomal proximal tubulopathy has reignited interest in its pathogenesis. Along with the representative feature of chronic interstitial nephritis, changes suggestive of tubular injury have also been reported. It is suggested to use the term “chronic tubulointerstitial nephropathy of agricultural community” instead of chronic interstitial nephritis of the agricultural communities. Chronic tubulointerstitial nephropathy in agricultural communities is a slowly progressive disease that initially does not cause any symptoms in patients and most patients have a delayed onset of symptoms. Several diagnostic criteria have been introduced over the past years and one introduced by the Ministry of Health of Sri Lanka is widely used. The management of this chronic illness is no different from other causes of chronic interstitial nephritis and our focus should be on implementing various preventive strategies to reduce its incidence in agricultural communities and protect the health and well-being of agricultural workers. By disseminating knowledge about chronic tubulointerstitial nephropathy in agricultural communities, we can contribute to the development of evidence-based interventions to reduce the burden of the disease on affected communities. Moreover, we would like to sensitize physicians to this entity to increase awareness and identify potential endemic areas in various agricultural communities.

Melatonin ameliorates glyphosate- and hard water-induced renal tubular epithelial cell senescence via PINK1-Parkin-dependent mitophagy

The combination of glyphosate (Gly) and hard water (Hwt) is a suspected risk factor for chronic interstitial nephritis in agricultural communities (CINAC). Accumulated mitochondrial damage and proximal tubular epithelial (PTE) cell senescence have been implicated in CINAC pathogenesis. Melatonin (Mel) has potential mitochondrial function and renoprotective properties, but its role and mechanism in CINAC are unknown. Here, we detected PTE cell senescence and PTEN-induced putative protein kinase 1 (PINK1)-parkin RBR E3 ubiquitin protein ligase (Parkin)-dependent mitophagy in mice orally administered with different doses of Gly combined with Hwt (Gly: 100 mg/kg·bw and 0.7 mg/L; Hwt: 2,500 mg/L CaCO3 and 250 mg/L Ca2+) for different durations (12 and 36 w) using histological examination, transmission electron microscopy (TEM), immunofluorescence (IF) analysis, and immunohistochemistry (IHC), immunoblotting, ELISA and biochemical assays with kits. The same assays were performed after combination treatment with Mdivi-1 (an inhibitor of mitophagy, i.p. 10 mg/kg·bw, twice a week for 12 w) or Mel (i.p. 10 mg/kg·bw, once a day for 12 w) under high-level exposure. Gly combined with Hwt (Gly-Hwt) significantly increased P16-P21-dependent PTE cell senescence, mitochondrial fission and oxidative stress, and activated PINK1-Parkin-mediated mitophagy, accompanied by defective autophagic flux at high doses but unaltered autophagic flux at low doses. Improved senescence occurred after Mdivi-1 administration, suggesting that mitophagy is involved in cellular senescence. Mel significantly decreased senescence induced by Gly-Hwt. Furthermore, PINK1-Parkin-dependent mitophagy and autophagic flux were markedly enhanced, and mitochondrial function was improved, as evidenced by reductions in mitochondrial fission and subsequent oxidative damage. Thus, Gly and Hwt synergistically promote PTE cell senescence through PINK1-Parkin-mediated mitophagy, and Mel exerts renoprotective effects by modulating mitophagy, suggesting therapeutic applications in ageing-related CINAC.

Does snake envenoming cause chronic kidney disease? A cohort study in rural Sri Lanka

Background There is limited information on the risk of chronic kidney disease (CKD) following snakebite and its relationship with chronic interstitial nephritis in agricultural communities (CINAC). We aimed to investigate CKD in patients with a confirmed snakebite in rural Sri Lanka. Methods Patients prospectively recruited to the Anuradhapura snakebite cohort with authenticated bites were followed up. Two groups of patients were followed up: 199 patients in group I with a snakebite (August 2013–October 2014), reviewed after 4 years, and 168 patients in group II with a snakebite (May 2017–August 2018), reviewed after one year, with serum creatinine (estimated glomerular filtration rate [eGFR]) and urinary albumin to creatinine ratio (ACR). Results There were 12/199 (6%) in group I and 9/168 (5%) in group II with AKI following snakebite; 3/12 in group I and 2/9 in group II had haemodialysis. On review after 1 and 4 years, no patient had CKD and all had an eGFR ≥60 mL/min/1.73m2. Of 234 patients with a creatinine measured on discharge, 17/140 in group I and 11/94 in group II had a low eGFR (<60mL/min/1.73m2). In group I, 14/17 had a normal eGFR after four years, including 11/12 who had AKI following snakebite, and the 3/17 with a low eGFR on review had CKD or co-morbidities for CKD. In group II, 10/11 had a normal eGFR after one year, including all nine patients with AKI following snakebite, and the one patient with a low eGFR on review had CKD. Fifty patients (25%) in group I and 43 (26%) in group II had a high urinary ACR on review, all but two in each group had microalbuminuria. Multivariate logistic regression showed in group I that only comorbidities for CKD were associated with high urinary ACR, and in group II comorbidities for CKD, snakebite associated AKI and snake type were associated with high urinary ACR. All nine patients from both groups with a low eGFR (CKD stages 3–5) had CKD prior to the snakebite or treatment for hypertension or diabetes. Conclusion There was no significant association between snakebite-associated AKI and CKD in patients followed up from a snakebite cohort post-bite. Microalbuminuria was common in these patients but likely associated with hypertension, diabetes mellitus and CINAC in this rural farming population.

Melatonin ameliorates renal dysfunction in glyphosate- and hard water-treated mice

Chronic interstitial nephritis in agricultural communities (CINAC) is a severe and widespread disease that has been associated with environmental and occupational exposure to glyphosate and hard water. However, the potential underlying mechanisms remain incompletely understood. Melatonin is reported to exert protective effects on the kidney, but whether melatonin can attenuate renal tubular injury in mice exposed to glyphosate combined with hard water is unclear. Here, mice were treated with high doses and environmentally relevant doses of glyphosate (100 mg/kg·bw and 0.7 mg/L, respectively) and/or hard water (2500 mg/L CaCO3 and 250 mg/L Ca2+, respectively) via their drinking water for 12 weeks. We found that high-dose glyphosate or hard water treatment significantly increased the levels of biomarkers of renal damage, including β2-microglobulin, neutrophil gelatinase-associated lipid carrier protein, and/or albumin, in the urine; these increased biomarker levels were correlated with obvious morphological changes, and all of these changes were also observed in animals exposed to environmentally relevant doses of glyphosate and/or high Ca2+ water. Melatonin (10 mg/kg·bw, intraperitoneal injection, daily for 12 weeks) administered concomitantly with high doses of glyphosate and hard water inhibited the glyphosate- and hard water-induced increases in the levels of kidney injury biomarkers and changes in morphology; this result was intriguing. Additionally, glyphosate combined with hard water at both high and environmentally relevant doses significantly upregulated the expression of the endoplasmic reticulum (ER) stress marker proteins Bip, ATF6, and PERK as well as the pyroptosis-related proteins (NLRP3 and caspase 1 signaling proteins) in renal tissues. Similarly, melatonin significantly attenuated the increased ER stress and pyroptosis induced by high doses of glyphosate and hard water. In summary, we conclude that exposure to glyphosate and hard water at both high doses and environmentally relevant doses causes renal dysfunction in mice, and this dysfunction can be attenuated by melatonin, possibly through the inhibition of ER stress and pyroptosis. Our results support the notion that melatonin may have therapeutic potential for the treatment of chronic kidney diseases.

Dysmorphic Lysosomes, Pathognomonic of Chronic Interstitial Nephritis in Agricultural Communities (CINAC)

Dysmorphic Lysosomes, Pathognomonic of Chronic Interstitial Nephritis in Agricultural Communities (CINAC)

Involvement of mitochondrial fission in renal tubular pyroptosis in mice exposed to high and environmental levels of glyphosate combined with hard water

Chronic interstitial nephritis in agricultural communities (CINAC) has reached epidemic proportions. The combination of glyphosate and hard water has been postulated to play a potent aetiological role in CINAC. Therefore, dynamin-related protein 1 (Drp1)-mediated aberrant mitochondrial fission and subsequent activation of the nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (Nlrp3)/caspase1 pathway may be involved in the pathogenesis of nephropathy. In the present study, mice were sub-chronically exposed to high doses and environmental levels of glyphosate (100 mg/kg body weight (mg/kg·bw) glyphosate in Roundup and 0.7 mg/L pure glyphosate, respectively) and hard water (2500 mg/L CaCO3 and 250 mg/L Ca2+, respectively) in drinking water. Moreover, Mdivi-1 (Md-1, 10 mg/kg·bw) was intraperitoneally injected to inhibit Drp1 on the basis of the high-dose experiment. Histopathological examination, biochemical analysis, ELISA, western blotting and fluorescent staining were used to analyse renal structure, renal tubular pyroptosis and mitochondrial fission/fusion alterations. The results showed dramatic proximal tubular injury, particularly in the combined groups. Moreover, significant increases in the protein expression levels of calmodulin (CaM), calmodulin-dependent protein kinase II (CaMKII), Drp1/p-Drp1-Ser616 and the Txnip/Nlrp3/caspase1 signalling pathway, and alterations in oxidative stress were observed in the combined groups, and these effects were attenuated by the Drp1 inhibitor Md-1. Intriguingly, there may be a synergistic effect of glyphosate and hard water on renal injury. Taken together, these results suggest that the combination of glyphosate and hard water, even at environmental exposure levels, enhances pyroptosis and ongoing tubulointerstitial inflammation through excessive Drp1-mediated mitochondrial fission.

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.

Is an Environmental Nephrotoxin the Primary Cause of CKDu (Mesoamerican Nephropathy)? PRO.

Chronic interstitial nephritis in agricultural communities (CINAC), also named CKD of unknown origin (CKDu) or Mesoamerican nephropathy (MeN), is defined as a form of CKD affecting young men and—less often—women. Its etiology is unrelated to diabetes, GN, hypertension, or other known causes of CKD. Patients with CINAC live and work mainly in poor agricultural communities, often in hot tropical regions, and are exposed to potentially toxic agrochemicals through work by ingestion of contaminated food and water, and/or by inhalation (1,2). The epidemic dimension of CINAC was first observed in the 1990s in Sri Lanka and Central America and has since been found to be an important cause of CKD-related deaths in an increasing number of countries (3,4). Patients with CINAC have bilateral, small, irregularly contoured kidneys with mutual size discrepancy of <1.5 cm on ultrasound, as observed in advanced cases of analgesic nephropathy and aristolochic nephropathy (5,6). Almost all patients with CINAC exhibit a proximal tubular lesion: tubular cell atrophy, basement membrane thickening, deficient proximal tubular cell (PTC) regeneration, loss of function, distal tubular proliferation/hypertrophy, and variable extents of interstitial fibrosis and cellular infiltration. Overt glomerular injury is rare in the early stages, whereas secondary glomerulosclerosis develops in later CKD stages. By electron microscopy, PTCs demonstrate enlarged dysmorphic lysosomes (≥1.2 µ m) containing homogenous nonmembrane-bound, electron-dense, rounded/irregular “aggregates” dispersed throughout the light-to-medium, uniform, electron-dense lysosomal matrix (7) (Figure 1). These features are also observed in a number of toxin-induced nephropathies. Figure 1. Overview of the constellation of proximal tubular lesions observed in patients with chronic interstitial nephritis in agricultural communities/CKD of unknown origin. (A) Proximal tubular cells containing many enlarged argyrophilic granules, demonstrated to be lysosomes (arrowheads) (7) (Periodic acid–Schiff methenamine [PASM] staining). (B) Affected proximal tubule demonstrating enlarged lysosomes, flattened atrophic epithelial cells with …

Is an Environmental Nephrotoxin the Primary Cause of CKDu (Mesoamerican Nephropathy)? Commentary.

The environmental nephrotoxin component as the etiology for CKD of unknown cause (CKDu) has been elegantly discussed in a debate by De Broe (pro) (1) and Wesseling (con) (2) in this issue of Kidney360 . The etiology of CKDu has been a topic of enormous controversy, and it seems that this same controversy has characterized this disease. Although it is currently unclear whether there is a unified underlying cause, these conditions have been collectively termed CKDu, but various names have emerged. They include the following: CKD of nontraditional cause, Mesoamerican nephropathy, chronic interstitial nephritis in agricultural communities, and kidney disease of unknown cause in agricultural laborers. I will refer to CKDu in my piece as it is a preferred and neutral term. It is evident that simple things, such as naming the disease or establishing a definition for CKDu, have generated enormous difficulties that create obstacles to the detection and optimal treatment. I would argue, however, that we do have consensus in some CKDu areas. First, we agree that those affected by CKDu do not have traditional risk factors or underlying conditions that lead to CKD, such as older age, diabetes mellitus, hypertension, GN, or structural kidney disease. …

P0141KIDNEY BIOPSY INDICATIONS AND OUTCOMES: SEVEN YEARS EXPERIENCE OF A SINGLE CENTRE IN SRI LANKA

Abstract Background and Aims Histopathological analysis of renal biopsy is the cornerstone of diagnosis in renal disease and guides treatment and prognosis. The prevalence of various renal diseases varies according to the geographical area, socioeconomic condition, race, age, demography and indication of renal biopsy. Method A retrospective study of all native and transplant kidney biopsies performed at the renal unit of Sri Jayewardenepura General Hospital, Sri Lanka, between 1st October 2012 and 30th September 2019. Samples were processed for light microscopy in all cases, with immunofluorescence in most cases. Results 771 biopsies were analyzed. Majority of biopsies 514 (67%) were male patients. Most biopsies (n= 345, 45%) were in 40 – 59yr age group, followed by 267 (35%) 20–39yr, 117 (15%) 60–69yr, 12 (1%) &amp;gt;70yrs, 30 (4%) 12–19yr age groups. Maximum age was 84 years. In 35 cases, tissue were inadequate. 547 (71%) were native biopsies and 224 (29%) were graft biopsies. Among transplants, majority was for an indication (n=146, 66%) followed by time-zeroes (n=59, 26%) and protocols (n=19, 9%). Rising creatinine (81%) was the strongest reason for transplant biopsies, next proteinuria (10%) and delayed graft function (7%). Time zeroes: majority were normal, few ATN, 1 chronic tubulointerstitial nephritis, and 1 hypertensive glomerulosclerosis. Grafts revealed, acute antibody-mediated rejection 41 (18%) with acute cell-mediated rejection 27 (12%), (total rejections n=68, 30%) followed by normal histology 48 (21%), acute tubular necrosis 43 (19%), chronic allograft nephropathy 23 (10%), BKV nephropathy 5 (2%), and 18% other etiologies: CNI-toxicity (n=4), hypertensive glomerulosclerosis (n=3), diabetic nephropathy (n=2), thrombotic microangiopathy (n=2), FSGS (n=2), MPGN (n=1), vasculitis (n=2), PTLD (n=1), cast nephropathy (n=1), and granulomatous interstitial nephritis (n=1). The most common indication for native biopsy was nephrotic syndrome 209 (38%), followed by non-proteinuric CKD 105 (19%), unexplained renal failure 77 (14%), sub-nephrotic proteinuria 102 (18%), nephritic syndrome 54 (9%). Primary glomerulonephritis (GN) was the commonest 291 (53%). Commonest lesion amidst primary GN was IgA nephropathy 90 (16%), followed by FSGS 63 (12%), CGN 27 (4%), minimal change 36 (6%), MPGN 32 (5%), membranous 6 (1%), DPGN 22 (4%), mesangiocapillary GN 3 (0.5%) and post-streptococcal GN 11 (2%). In the secondary forms of GN, SLE was the commonest 39 (7%), next diabetic nephropathy 29 (5%), amyloidosis 2 (0.3%). Chronic tubulointerstitial nephritis 92 (16%) was the second common, with 42 (7%) CINAC – chronic interstitial nephritis in agricultural communities. Other etiologies: acute tubulointerstitial nephritis 14 (2.5%), hypertensive glomerulosclerosis 12 (2%), thrombotic microangiopathy 6 (1%), ischemic nephropathy 9 (1%), end stage disease 6 (1%), inconclusive 13 (2%). 5 cast nephropathy due to multiple myeloma, 1 monoclonal deposition disease due to lambda chain deposition, 1 sarcoidosis, 1 cholesterol embolism. Conclusion Female: male ratio 1:2 with commonest age group being 40 – 59yrs. Strongest indication for transplant biopsy was rising creatinine. Acute rejection was the most frequent finding in grafts, with normal histology being the next, probably due to high number of time zeroes and protocols performed in our centre. Biopsy proven BKV nephropathy was 2% (n=5). Nephrotic range proteinuria was the commonest native biopsy indication, with non-proteinuric CKD being the second. Primary GN was the commonest finding with IgA nephropathy scoring the highest. This does not coincide with global data, which shows FSGS to be the leading cause. The second common histology was FSGS, and primary CTIN was third. The prevalence of biopsy-proven GN varies due to a wide array of factors and different studies have shown different leading patterns.

Uncovering the etiology of CINAC, a complex and mysterious renal syndrome: the invaluable role of histopathology and electron microscopy

Chronic interstitial nephritis in agricultural communities (CINAC) is a progressive form of tubulointerstitial nephritis affecting agricultural workers in different parts of the world. Its underlying etiology is not known, although a study by Vervaet and coworkers in this issue of Kidney International provides strong evidence that CINAC is a lysosomal tubulopathy induced by toxin exposure. Key to this important discovery is a thorough morphologic analysis of kidney tissue, including ultrastructural as well as histopathologic examination.

Toxins linked to chronic interstitial nephritis in agricultural communities.

Toxins linked to chronic interstitial nephritis in agricultural communities.

Chronic interstitial nephritis in agricultural communities is a toxin-induced proximal tubular nephropathy

Almost 30 years after the detection of chronic interstitial nephritis in agricultural communities (CINAC) its etiology remains unknown. To help define this we examined 34 renal biopsies from Sri Lanka, El Salvador, India and France of patients with chronic kidney disease 2-3 and diagnosed with CINAC by light and electron microscopy. In addition to known histopathology, we identified a unique constellation of proximal tubular cell findings including large dysmorphic lysosomes with a light-medium electron-dense matrix containing dispersed dark electron-dense non-membrane bound "aggregates". These aggregates associated with varying degrees of cellular/tubular atrophy, apparent cell fragment shedding and no-weak proximal tubular cell proliferative capacity. Identical lysosomal lesions, identifiable by electron microscopy, were observed in 9% of renal transplant implantation biopsies, but were more prevalent in six month (50%) and 12 month (67%) protocol biopsies and in indication biopsies (76%) of calcineurin inhibitor treated transplant patients. The phenotype was also found associated with nephrotoxic drugs (lomustine, clomiphene, lithium, cocaine) and in some patients with light chain tubulopathy, all conditions that can be directly or indirectly linked to calcineurin pathway inhibition or modulation. One hundred biopsies of normal kidneys, drug/toxin induced nephropathies, and overt proteinuric patients of different etiologies to some extent could demonstrate the light microscopic proximal tubular cell changes, but rarely the electron microscopic lysosomal features. Rats treated with the calcineurin inhibitor cyclosporine for four weeks developed similar proximal tubular cell lysosomal alterations, which were absent in a dehydration group. Overall, the finding of an identical proximal tubular cell (lysosomal) lesion in CINAC and calcineurin inhibitor nephrotoxicity in different geographic regions suggests a common paradigm where CINAC patients undergo a tubulotoxic mechanism similar to calcineurin inhibitor nephrotoxicity.

Chronic kidney disease of undetermined aetiology: tens of thousands of premature deaths, yet too much remains unknown.

Tens of thousands of working-age adults have been dying from unexplained end-stage renal disease (ESRD) in Central America and South Asia. As the cause of this chronic kidney disease (CKD) remains unknown, the condition(s) (a unified aetiopathology has not been confirmed) has been termed ‘CKD of undetermined aetiology’ (CKDu). ‘CKD of non-traditional aetiology’, ‘chronic interstitial nephritis in agricultural communities’, ‘Mesoamerican nephropathy’, ‘Sri Lankan agricultural nephropathy’ and ‘Uddanam nephropathy’ are also used, but here we use the term CKDu.

Early renal damage among children living in the region of highest burden of chronic kidney disease of unknown etiology (CKDu) in Sri Lanka

BackgroundChronic kidney disease of unknown origin (CKDu) in Sri Lanka is grouped with several other epidemics of similar nature across the world as Chronic Interstitial Nephritis in Agricultural Communities (CINAC). In CKDu endemic countries, the focus has mainly been on adults. We hypothesized that studying distribution and factors associated with elevated urine albumin to creatinine ratio (UACR), an early marker of kidney injury, among children living in a CKDu endemic area may provide important clues about the onset and progression of the disease.MethodsThis cross sectional study was performed in rural primary schools in North Central Province of Sri Lnaka, a CKDu high endemic region. Total of 2880 students aging 5 to 11 years from 67 schools were enrolled for urinalysis in a random spot urine sample. Bedside Schwartz formula was used to measure estimated glomerular filtration rate (eGFR) on all children with UACR > 30 mg/g in Polonnaruwa district and a group of age matched controls. A standard multiple linear regression using log transformed UACR as the dependent variable was performed. Mean eGFR were compared between UACR elevated group and controls using independent sample t test.ResultsMedian UACR was 10.3 mg/g. Sex, ethnicity, history of having a chronic disease and age uniquely contributed to the multiple regression model which only explained 2.8% of the variance in the log of the UACR (p < 0.001). Only 15 (0.5%) had UACR> 300 mg/g while 8.2% (n = 236) had UACR between 30 to 300 mg/g and 89.8% (n = 203) of them did not have a chronic disease (Chi square 2.21, p = 0.091). Mean eGFR was significantly lower in the group with elevated UACR (88.9 mg/dl/1.73 m2, 95% CI for mean 86.4- 91.3) compared to group with normal UACR (93.7 mg/dl/1.73 m2,95% CI 91.1- 96.3) (t 2.7, p 0.007). Three out of the four students with eGFR less than 60 mg/dl/1.73 m2 had moderately elevated UACR.ConclusionThis study provides evidence to suggest that children in CKDu endemic regions are having an early renal damage. This observation needs to be investigated further in order to understand the worldwide epidemic of CKDu.

Toward a Comprehensive Hypothesis of Chronic Interstitial Nephritis in Agricultural Communities.

Over the past 20years, there has been an increase in chronic interstitial nephritis in agricultural communities (CINAC) not associated with traditional risk factors. This disease has become an important public health problem and is observed in several countries in Central America and Asia. CINAC predominantly affects young male farmers between the third and fifth decades of life with women, children, and adolescents less often affected. Clinically, CINAC behaves like a chronic tubulointerstitial nephropathy but with systemic manifestations not attributable to kidney disease. Kidney biopsy reveals chronic tubulointerstitial nephritis with variable glomerulosclerosis and mild chronic vascular damage, with the severity depending on sex, occupation, and CKD stage. The presence of toxicological, occupational, and environmental risk factors within these communities suggests a multifactorial etiology for CINAC. This may include exposure to agrochemicals, a contaminated environment, repeated episodes of dehydration with heat stress, and an underlying genetic predisposition. An understanding of these interacting factors using a multidisciplinary approach with international cooperation and the formulation of a comprehensive hypothesis are essential for the development of public health programs to prevent this devastating epidemic.