Leptospirosis: A Potential Culprit for Chronic Kidney Disease of Uncertain Etiology.

PURPOSE: Chronic kidney disease of uncertain etiology (CKDu) is an environmental nephropathy in which the etiological factors are yet uncertain. Leptospirosis, a spirochetal infection that is common among agricultural communities, has been identified as a potential etiology for CKDu beyond environmental nephropathy. Although CKDu is a chronic kidney disease, in endemic regions, an increasing number of cases are reported with features suggestive of acute interstitial nephritis without any known reason (AINu), with or without background CKD. The study hypothesizes that exposure to pathogenic leptospires is one of the causative factors for the occurrence of AINu. METHOD: This study was carried out using 59 clinically diagnosed AINu patients, 72 healthy controls from CKDu endemic region (endemic controls [ECs]), and 71 healthy controls from CKDu non-endemic region (non-endemic controls [NECs]). RESULTS: The seroprevalence of 18.6, 6.9, and 7.0% was observed in the AIN (or AINu), EC, and NEC groups, respectively, from the rapid IgM test. Among 19 serovars tested, the highest seroprevalence was observed at 72.9, 38.9, and 21.1% in the AIN (AINu), EC, and NEC groups, respectively, by microscopic agglutination test (MAT), particularly for serovar Leptospira santarosai serovar Shermani. This emphasizes the presence of infection in AINu patients, and this also suggests that Leptospira exposure might play an important role in AINu. CONCLUSION: These data suggest that exposure to Leptospira infection could be one of the possible causative factors for the occurrence of AINu, which may lead to CKDu in Sri Lanka.

Murine Renal Transcriptome Profiles Upon Leptospiral Infection: Implications for Chronic Kidney Diseases.

Background: Leptospirosis caused by pathogenic Leptospira spp leads to kidney damage that may progress to chronic kidney disease. However, how leptospiral infections induced renal damage is unclear. Methods: We apply microarray and next-generation sequencing technologies to investigate the first murine transcriptome-wide, leptospires-mediated changes in renal gene expression to identify biological pathways associated with kidney damage. Results: Leptospiral genes were detected in renal transcriptomes of mice infected with Leptospira interrogans at day 28 postinfection, suggesting colonization of leptospires within the kidney with propensity of chronicity. Comparative differential gene expression and pathway analysis were investigated in renal transcriptomes of mice infected with pathogens and nonpathogens. Pathways analysis showed that Toll-like receptor signaling, complements activation, T-helper 1 type immune response, and T cell-mediated immunity/chemotaxis/proliferation were strongly associated with progressive tubulointerstitial damage caused by pathogenic leptospiral infection. In addition, 26 genes related with complement system, immune function, and cell-cell interactions were found to be significantly up-regulated in the L interrogans-infected renal transcriptome. Conclusions: Our results provided comprehensive knowledge regarding the host transcriptional response to leptospiral infection in murine kidneys, particularly the involvement of cell-to-cell interaction in the immune response. It would provide valuable resources to explore functional studies of chronic renal damage caused by leptospiral infection.

Overlooked Risk for Chronic Kidney Disease after Leptospiral Infection: A Population-Based Survey and Epidemiological Cohort Evidence.

BACKGROUND: Leptospirosis is the most widespread zoonosis. Chronic human infection and asymptomatic colonization have been reported. However, renal involvement in those with leptospira chronic exposure remains undetermined. METHODS AND FINDINGS: In 2007, a multistage sampling survey for chronic kidney disease (CKD) was conducted in a southern county of Taiwan, an area with a high prevalence of dialysis. Additionally, an independent cohort of 88 participants from a leptospira-endemic town was followed for two years after a flooding in 2009. Risks of CKD, stages of CKD, associated risk factors as well as kidney injury markers were compared among adults with anti-leptospira antibody as defined by titers of microscopic agglutination test (MAT). Of 3045 survey participants, the individuals with previous leptospira exposure disclosed a lower level of eGFR (98.3 ± 0.4 vs 100.8 ± 0.6 ml/min per 1.73 m2, P < 0.001) and a higher percentage of CKD, particularly at stage 3a-5 (14.4% vs 8.5%), than those without leptospira exposure. Multivariable linear regression analyses indicated the association of leptospiral infection and lower eGFR (95% CI -4.15 to -1.93, P < 0.001). In a leptospiral endemic town, subjects with a MAT titer ≥ 400 showed a decreased eGFR and higher urinary kidney injury molecule-1 creatinine ratio (KIM1/Cr) level as compared with those having lower titers of MAT (P < 0.05). Furthermore, two participants with persistently high MAT titers had positive urine leptospira DNA and deteriorating renal function. CONCLUSIONS AND SIGNIFICANCE: Our data are the first to show that chronic human exposure of leptospirosis is associated significantly with prevalence and severity of CKD and may lead to deterioration of renal function. This study also shed light on the search of underlying factors in areas experiencing CKD of unknown aetiology (CKDu) such as Mesoamerican Nephropathy.