Presentation Summary

Written by Jasna Trbojevic-Stankovic
Reviewed by Marc De Broe and Benjamin Vervaet

Chronic interstitial nephritis in agricultural communities (CINAC)
In 1995 an outbreak of acute kidney injury manifesting with chronic nephritis and resulting in chronic kidney disease (CKD) has been noticed in Central America, Sri Lanka and other tropical countries. The condition has been named chronic interstitial nephritis in agricultural communities (CINAC), since it predominantly appeared in farming communities. The established minimal set of clinical diagnostic criteria for CINAC included: residence in agricultural communities in tropical climate, predominance of young males, and absence of diabetes, hypertension, glomerulopathies or other known causes of CKD (1).

A quarter of the century later, etiology of CINAC is still obscure. The condition appears to be multifactorial, with various hypotheses being proposed. Several factors have been suggested as possible triggers, including heat stress, episodes of repeated dehydration, and exposures to toxic agrochemicals through work, ingestion of contaminated food and water, or by inhalation of toxic substances in the agricultural communities. Evidence supports occupational and environmental toxins as the primary trigger (1). However, diagnosis is still based on exclusion criteria.

Renal biopsy study of CINAC patients
Renal biopsies and patohysiological analysis are of crucial importance in patients presenting with clinical symptoms suggestive of CINAC. Analysis of collections of kidney biopsies from patients with clinical manifestation of CINAC from El Salvador, France, India and Sri Lanka returned compelling results, as presented on Figure 1. The most remarkable feature observed with light microscopy in virtually all examined samples was a remarkable accumulation of large granules in proximal tubular cells, with some granules demonstrating clear dysmorphia and containing dispersed intragranular aggregates (2).

Figure 1. Jones-stained sections revealed prominent accumulation of intracellular granules (identified as lysosomes) with different phenotypic appearances. Prominent enlarged granules, some with irregular/dysmorphic shapes and heterogenous content. B and D respresent the squares in A and C, respectively. Image Images from Sri Lankan CINAC patients. Image C and D reproduced from supplemental figure S2 of Vervaet et al., who published as an open access article under the CC BY- NC-ND license (

The immunofluorescence microscopy analysis revealed autofluorescence of the observed granules. Furthermore, when stained with Jones silver staining, the granules, predominantly present in the proximal tubular cells from segment S1 to S3, showed notable argyrophilia. Other observed features on proximal tubular cells included conserved height, but noticeable atrophy, apical blebbing, thickening of the basement membrane, interstitial expansion, fibrosis and defective proliferation. All these alterations suggested a remarkable deterioration of regenerative capacity (2).

Further investigation addressed the origin of the CINAC granules. They exhibited positive staining for Cathepsin B and lysosome-associated membrane protein 1 (LAMP-1). Electron microscopy analysis demonstrated dysmorphic intracellular granules containing dispersed electron dense aggregates in the proximal tubular epithelial cells (Figure 2). The observations were comparable with light microscopy, but there was still insufficient data to confirm these were lysosomes. The final confirmation came from a specific technique, called the Transmission Electron Microscopy Energy-Dispersive X-ray spectroscopy (TEM-EDX), which was applied on the Jones stained tissue section, verifying that observed granules in fact originated from lysosomes.

The connection between lesions in CINAC patients and patients treated with calcineurin-inhibitors
Analysis of biopsy samples from patients with suspected CINAC from different parts of the world showed remarkable similarity, suggesting an epidemic of very large proportion (Figure 2).

Figure 2. CINAC patients across the world have the same histopathological appearance. Panels A, C, E, G are Jones stainined sections; panels B, D, F, H are electronmicroscopic images. Images A-H reproduced from figure 11 of Vervaet et al., who published as an open access article under the CC BY- NC-ND license (

Furthermore, when samples from patients with CINAC, non- CINAC nephropathies and normal controls were compared, a striking similarity was observed between the lesions in CINAC patients and transplant patients on calcineurin inhibitors (CIN) therapy (6-9). This led to a conclusion that possible toxic cause of CINAC promotes the same alterations of tissue morphology as CIN (5-8). The CIN-related tissue alterations, including the appearance of dysmorphic lysosomes, eventually progress over time, probably due to the acquired phenotype associated with exposure to nephrotoxic drugs that inhibit calcineurin (10-13).

The search for the connection between the CINAC and CIN-related lesions returned several possible reciprocities. Certain pesticides, such as synthetic pyrethroids and chlorinated hydrocarbon insecticides, exhibit direct inhibition on calcineurin (14). Moreover, they activate reactive oxygen species (ROS), which also impede calcineurin effects (15-17). Furthermore, several agrochemicals, such as paraquat, roundup and several others, are able to induce ROS (18-21). These mechanisms might represent the possible link between agrochemicals and CIN.


1. Jayasumana C, Orantes C, Herrera R, et al. Chronic interstitial nephritis in agricultural communities: a worldwide epidemic with social, occupational and environmental determinants. Nephrol Dial Transplant. 2017;32(2):234-241. doi:10.1093/ndt/gfw346

2. Vervaet B, Nast C, Jayasumana C, Schreurs G, Roels F, Herath C, Kojc N, Samaee V, Rodrigo S, Gowrishankar S, Mousson C, Dassanayake R, Orantes C, Vuiblet V, Rigothier C, D’Haese P, De Broe M. Chronic interstitial nephritis in agricultural communities is a toxin-induced proximal tubular nephropathy. Kidney Int. 2020 Feb;97(2):350-369.

3. Wijkström J, Leiva R, Elinder CG, et al. Clinical and pathological characterization of Mesoamerican nephropathy: a new kidney disease in Central America. Am J Kidney Dis. 2013;62(5):908-918. doi:10.1053/j.ajkd.2013.05.019

4. López-Marín L, Chávez Y, García XA, et al. Histopathology of chronic kidney disease of unknown etiology in Salvadoran agricultural communities. MEDICC Rev. 2014;16(2):49-54.

5. De Broe M. Chronic kidney disease of unknown etiology: population-level detection strategies.Presented at the 57th European Reanal Association – European Dialysis Transplantation Association Congress (fully virtual), June 8, 2020. Available on the Virtual Meeting.

6. Liu J. FK506 and cyclosporin, molecular probes for studying intracellular signal transduction [published correction appears in Immunol Today 1993 Aug;14(8):399] [published correction appears in Immunol Today. 2008 Apr;29(4):149]. Immunol Today. 1993;14(6):290-295. doi:10.1016/0167-5699(93)90048-P

7. Sieber M, Baumgrass R. Novel inhibitors of the calcineurin/NFATc hub – alternatives to CsA and FK506?. Cell Commun Signal. 2009;7:25. Published 2009 Oct 27. doi:10.1186/1478-811X-7-25

8. Naesens M, Kuypers DR, Sarwal M. Calcineurin inhibitor nephrotoxicity. Clin J Am Soc Nephrol. 2009;4(2):481-508. doi:10.2215/CJN.04800908

9. Sigal NH, Dumont F, Durette P, et al. Is cyclophilin involved in the immunosuppressive and nephrotoxic mechanism of action of cyclosporin A?. J Exp Med. 1991;173(3):619-628. doi:10.1084/jem.173.3.619

10. Mann DM, Vanaman TC. Modification of calmodulin on Lys-75 by carbamoylating nitrosoureas. J Biol Chem. 1988;263(23):11284-11290.

11. Musgrove EA, Wakeling AE, Sutherland RL. Points of action of estrogen antagonists and a calmodulin antagonist within the MCF-7 human breast cancer cell cycle. Cancer Res. 1989;49(9):2398-2404.

12. Gómez-Sintes R, Lucas JJ. NFAT/Fas signaling mediates the neuronal apoptosis and motor side effects of GSK-3 inhibition in a mouse model of lithium therapy. J Clin Invest. 2010;120(7):2432-2445. doi:10.1172/JCI37873

13. Hu XT, Ford K, White FJ. Repeated cocaine administration decreases calcineurin (PP2B) but enhances DARPP-32 modulation of sodium currents in rat nucleus accumbens neurons. Neuropsychopharmacology. 2005;30(5):916-926. doi:10.1038/sj.npp.1300654

14. Enan E, Matsumura F. Specific inhibition of calcineurin by type II synthetic pyrethroid insecticides. Biochem Pharmacol. 1992;43(8):1777-1784. doi:10.1016/0006-2952(92)90710-z

15. Ghosh MC, Wang X, Li S, Klee C. Regulation of calcineurin by oxidative stress. Methods Enzymol. 2003;366:289-304. doi:10.1016/s0076-6879(03)66022-2

16. Carruthers NJ, Stemmer PM. Methionine oxidation in the calmodulin-binding domain of calcineurin disrupts calmodulin binding and calcineurin activation. Biochemistry. 2008;47(10):3085-3095. doi:10.1021/bi702044x

17. Zhou X, Mester C, Stemmer PM, Reid GE. Oxidation-induced conformational changes in calcineurin determined by covalent labeling and tandem mass spectrometry. Biochemistry. 2014;53(43):6754-6765. doi:10.1021/bi5009744

18. Jabłońska-Trypuć A, Wołejko E, Wydro U, Butarewicz A. The impact of pesticides on oxidative stress level in human organism and their activity as an endocrine disruptor. J Environ Sci Health B. 2017;52(7):483-494. doi:10.1080/03601234.2017.1303322

19. de Liz Oliveira Cavalli VL, Cattani D, Heinz Rieg CE, et al. Roundup disrupts male reproductive functions by triggering calcium-mediated cell death in rat testis and Sertoli cells. Free Radic Biol Med. 2013;65:335-346. doi:10.1016/j.freeradbiomed.2013.06.043

20. Uren Webster TM, Santos EM. Global transcriptomic profiling demonstrates induction of oxidative stress and of compensatory cellular stress responses in brown trout exposed to glyphosate and Roundup. BMC Genomics. 2015;16(1):32. Published 2015 Jan 31. doi:10.1186/s12864-015-1254-5

21. Wang X, Luo F, Zhao H. Paraquat-induced reactive oxygen species inhibit neutrophil apoptosis via a p38 MAPK/NF-κB-IL-6/TNF-α positive-feedback circuit. PLoS One. 2014;9(4):e93837. Published 2014 Apr 8. doi:10.1371/journal.pone.0093837

NEP – E Summary Articles