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

Kidney involvement in leptospirosis: a systematic review and meta-analysis

INTRODUCTION

From a public health perspective, it is essential to understand the burden of kidney involvement in leptospirosis. We aimed to assess the frequency of acute kidney injury (AKI) and chronic kidney disease (CKD) in patients with leptospirosis.

METHODOLOGY

This systematic review and meta-analysis included all articles up to 14.08.2024 from three databases (PubMed, Scopus, Web of Science) using search terms related to leptospirosis and kidney involvement. After de-duplication, two independent reviewers independently checked the articles in two phases (title-abstract and full-text), and a third reviewer adjudicated any conflicts. Patient demographics, diagnostic procedures, and details of kidney involvement were extracted from the included studies. Risk of bias analysis was done using the Joanna Briggs Institute critical appraisal tool. A random effects model estimated the pooled rates for AKI, oliguria, and the need for dialysis.

RESULTS

Of the 5913 retrieved articles, 48 met the eligibility criteria. The pooled incidence of AKI, reduced urine output, and dialysis requirement was 49.2% (95%CI: 38.2-60.2%, I2 of 99.4%), 31.5% (95%CI: 24.2-38.7%, I2-96.1%) and 14.4% (95%CI: 10.3-18.4%, I2-97%) respectively. The pooled mean serum creatinine and urea levels at admission were 3.6 mg/dl (95% CI: 2.9-4.2, I2-99.1%) and 131.8 mg/dl (95% CI: 98.7-164.9, I2-98.6%), respectively. In four studies, the incidence of new-onset CKD after leptospirosis infection varied from 13 to 62%.

CONCLUSION

AKI reduced urine output and the requirement for dialysis are frequent complications in patients with leptospirosis. Increased resources for their management in endemic areas are essential to mitigate the burden.

Role of Toll-like receptor 2 during infection of Leptospira spp: A systematic review

The involvement of Toll-like receptor 2 (TLR2) in leptospirosis is poorly understood. Our systematic review examined its role across in-vitro, in-vivo, ex-vivo, and human studies. Original articles published in English up to January 2024, exploring the role of TLR2 during leptospirosis, were selected from databases including PubMed, Web of Science, Scopus, Trip, and Google Scholar. Cochrane guidelines and Preferred Reporting Items for Systematic Reviews and Meta-Analyses were followed by this systematic review. The National Institute of Health Quality Assessment tool, Systematic Review Centre for Laboratory Animal Experimentation risk of bias tool, and Office of Health Assessment and Translation extended tool were used to assess the risk of bias of the studies. Out of 2458 studies retrieved, 35 were selected for the systematic review. These comprised 3 human, 17 in-vitro, 5 in-vivo, 3 ex-vivo, and 7 studies with combined experimental models. We assessed the direct TLR2 expression and indirect TLR2 involvement via the secretion/mRNA expression of immune effectors during leptospirosis. Notably, we observed the secretion/mRNA expression of several cytokines (IL6, IL8, IL-1β, TNFα, IFNγ, IL10, CCL2/MCP-1, CCL10, COX2, CXCL1/KC, CXCL2/MIP2) and immune effectors (hBD2, iNOS, Fibronectin, Oxygen, and Nitrogen reactive species) as key aspects of host TLR2 responses during leptospirosis. Even though increased TLR2 expression in in-vivo and in-vitro studies was evident, human studies reported mixed results showing that the postulated effect of TLR2 response based on other studies may not be valid for human leptospirosis. Besides the role of TLR2 in response to leptospirosis, the involvement of TLR4 and TLR5 was identified in in-vitro and in-vivo studies. TLR2 expression is inconclusive during human leptospirosis and further studies are needed to examine the immune effector regulation, through TLR2 for mitigating the harmful effects and promoting effective immune responses.

Uncovering latent infections in kidneys: A novel molecular approach for differential Leptospira detection

Leptospirosis, a re-emerging zoonotic disease caused by Leptospira spp., poses significant global health and veterinary challenges. Long-term colonization of renal tubules by Leptospira in asymptomatic hosts highlights the need for sensitive detection methods. This study evaluates the chronic or latent Leptospira infections in kidneys using a novel molecular approach to examine individual immune responses differences. Digital PCR strategies employing newly developed primer-probe sets targeting the flagellar fliG gene were used to assess the presence of trace Leptospira in infected murine kidneys and urine samples from laboratory-confirmed leptospirosis patients. RNA-based digital PCR detected leptospires in 58 % (targeting lipl32) and 83 % (targeting fliG) of infected kidneys, demonstrating that the digital PCR strategy targeting the fliG gene offers superior sensitivity. Notably, the newly developed fliG-targeting assay detected as low as 20 fg of Leptospira DNA, offering ten-fold greater sensitivity than traditional qPCR for trace detection. This allows for differential detection of Leptospira species and facilitates monitoring of extremely low bacterial loads with greater sensitivity than conventional methods. We also observed regenerating renal tubules with mitosis and elevated cytokine expression in kidneys with transcriptionally active Leptospira during chronic infection. This approach aids in identifying latent infections and offers insights into individual variations. Our research provides a powerful molecular tool for epidemiological studies and public health surveillance, contributing valuable insights into the prevalence and transmission dynamics of this pervasive zoonotic disease.

Oliguria as a diagnostic marker of severe leptospirosis: a study from the Transcarpathian region of Ukraine

Leptospirosis is an emerging illness presenting a broad range of clinical manifestations, ranging from asymptomatic or mild cases to severe and fatal outcomes. Early detection is crucial for effective treatment; however, similar clinical presentations in various febrile illnesses or co-infections, along with challenges in laboratory diagnostics, can lead to misdiagnosis and severe consequences. Identifying clinical predictors for severe forms of the disease is essential in mitigating complications and reducing mortality. Consequently, we conducted a retrospective case-control study to identify clinical markers indicative of severe disease in leptospirosis patients from the Transcarpathian region. The study focused on patients admitted with clinically suspected leptospirosis, involving a total of 51 diagnosed cases, with 13 resulting in severe outcomes and death. Categorical variables were analyzed using χ2, revealing a mean patient age of 50 years, predominantly male (n = 36, 70.5%). Oliguria emerged as a significant independent factor associated with mortality (odds ratio [OR], 13.5; 95% confidence interval [CI], 2.56-71.12; p = 0.001). Additionally, our analysis uncovered a noteworthy increase in leptospirosis notification rates in Transcarpathian compared to Ukraine, with 150 cases out of the total 433 in Ukraine. The highest notification rates were observed in Mukachevo District and Perechyn District. These findings highlight the importance of early recognition of key clinical markers, such as oliguria, which are critical for predicting severe outcomes in leptospirosis patients. The higher notification rates in Transcarpathian regions also underscore the need for enhanced surveillance, targeted public health interventions, and timely treatment to reduce mortality in endemic areas.

Leptospirosis: A dual threat - predisposing risk for renal transplant and trigger for renal transplant dysfunction

Leptospirosis (LTPS) is a bacterial infection that affects humans, often with mild or no symptoms. It is estimated that approximately 10 % of patients with LTPS may experience multi-organ dysfunction, including renal abnormalities. In regions where LTPS is widespread, a considerable number of instances involving acute kidney injury (AKI) and chronic kidney disease (CKD) of unknown etiology (CKDu) have been reported. Additionally, studies have shown a correlation between kidney graft dysfunction in patients with stable kidney transplants after LTPS. These findings indicate that exposure to LTPS may increase the likelihood of kidney transplantation due to the onset of both acute and chronic kidney injuries. Simultaneously, it poses a potential risk to the stability of kidney grafts. Unfortunately, there is limited scientific literature addressing this issue, making it difficult to determine the negative impact that LTPS may have, such as its role as a risk factor for the need of kidney transplantation or as a threat to individuals who have undergone kidney transplants. This study aims to shed light on the immune mechanisms triggered during LTPS infection and their importance in both kidney damage and allograft dysfunction.

Blocking pathogenic Leptospira invasion with aptamer molecules targeting outer membrane LipL32 protein

This study aimed to develop aptamers targeting LipL32, a most abundant lipoprotein in pathogenic Leptospira, to hinder bacterial invasion. The objectives were to identify high-affinity aptamers through SELEX and evaluate their specificity and inhibitory effects. SELEX was employed to generate LipL32 aptamers (L32APs) over 15 rounds of selection. L32APs' binding affinity and specificity for pathogenic Leptospira were assessed. Their ability to inhibit LipL32-ECM interaction and Leptospira invasion was investigated. Animal studies were conducted to evaluate the impact of L32AP treatment on survival rates, Leptospira colonization, and kidney damage. Three L32APs with strong binding affinity were identified. They selectively detected pathogenic Leptospira, sparing non-pathogenic strains. L32APs inhibited LipL32-ECM interaction and Leptospira invasion. In animal studies, L32AP administration significantly improved survival rates, reduced Leptospira colonies, and mitigated kidney damage compared to infection alone. This pioneering research developed functional aptamers targeting pathogenic Leptospira. The identified L32APs exhibited high affinity, pathogen selectivity, and inhibition of invasion and ECM interaction. L32AP treatment showed promising results, enhancing survival rates and reducing Leptospira colonization and kidney damage. These findings demonstrate the potential of aptamers to impede pathogenic Leptospira invasion and aid in recovery from Leptospira-induced kidney injury (190 words).

Differential expression of six cytokines in Rattus rattus exposed to leptospirosis: A comprehensive transcriptomic analysis

BACKGROUND

Rattus rattus are the main carriers of various zoonotic diseases including leptospirosis. Regrettably, information underlying the cytokine response of wild R. rattus upon leptospirosis infection is lacking. This study aims to understand the immune response presented by specifically the kidney and liver of R. rattus during leptospirosis infection.

METHODOLOGY

High-throughput RNA-Sequencing technology was employed to discover the transcriptome alterations in the kidney and liver of R. rattus during natural infection. Both kidney and liver tissues from the healthy and infected rats were sequenced using the BGISEQ-500 sequencing platform. The GO and KEGG databases were utilized to functionally annotate the differentially expressed transcripts of the selected cytokines; TNF-α, IL-1β, IL-6, IL-10, MIP-1α, and IFN-γ.

RESULTS

A higher number of upregulated genes were signified in the kidney as compared to the liver during infection. Among the six selected cytokines, Interleukin-6 was found to be expressed during the early stage in the liver of R. rattus, while all the other six genes were upregulated during the late stage of leptospirosis in the kidney of R. rattus. The GO of the annotated genes was classified under inflammatory response and cellular response to lipopolysaccharide, while the KEGG pathway indicated cytokine-cytokine receptor interaction and the Toll-like receptor (TLR) signalling pathway. The upshots of this study correlated the different phases of cytokine response in different organs of R. rattus during leptospirosis infection.

CONCLUSION

Overall, these studies formulate a conceptual framework based on host and pathogen relationships of leptospirosis transmission patterns and the discovery of biomarkers in tracking the early stages of leptospires colonization.

Neglected and Emerging Infections of The Kidney

Individuals, societies, and the environment are affected by neglected and emerging diseases. These diseases result in a variety of severe outcomes, including permanent disabilities, chronic diseases such as chronic kidney disease, and even mortality. Consequences include high health care expenditures, loss of means of support, social stigma, and social exclusion. The burden of these diseases is exacerbated in low- and middle-income countries owing to poverty, inadequate fundamental infrastructure, and the absence of health and social protection systems. The World Health Organization is committed to promoting the following public health strategies to prevent and control neglected tropical diseases: preventive chemotherapy; intensive case management; vector control; provision of safe drinkable water, sanitation, and hygiene; and veterinary public health. In addition, it promotes a One Health strategy, which is a collaborative, multisectoral, and interdisciplinary approach to achieving the greatest health outcomes by recognizing the interdependence of human beings, animals, plants, and their shared environment. This article provides knowledge and strategies for the prevention and treatment of neglected and emerging diseases, with a particular concentration on kidney diseases, as part of a comprehensive approach to One Health.

Leptospirosis kidney disease: Evolution from acute to chronic kidney disease

Leptospirosis is a neglected bacterial disease caused by leptospiral infection that carries a substantial mortality risk in severe cases. Research has shown that acute, chronic, and asymptomatic leptospiral infections are closely linked to acute and chronic kidney disease (CKD) and renal fibrosis. Leptospires affect renal function by infiltrating kidney cells via the renal tubules and interstitium and surviving in the kidney by circumventing the immune system. The most well-known pathogenic molecular mechanism of renal tubular damage caused by leptospiral infection is the direct binding of the bacterial outer membrane protein LipL32 to toll-like receptor-2 expressed in renal tubular epithelial cells (TECs) to induce intracellular inflammatory signaling pathways. These pathways include the production of tumor necrosis factor (TNF)-α and nuclear factor kappa activation, resulting in acute and chronic leptospirosis-related kidney injury. Few studies have investigated the relationship between acute and chronic renal diseases and leptospirosis and further evidence is necessary. In this review, we intend to discuss the roles of acute kidney injury (AKI) to/on CKD in leptospirosis. This study reviews the molecular pathways underlying the pathogenesis of leptospirosis kidney disease, which will assist in concentrating on potential future research directions.

Integrated Metabolomic and Transcriptomic Analysis of Acute Kidney Injury Caused by Leptospira Infection

Renal leptospirosis caused by leptospiral infection is characterised by tubulointerstitial nephritis and tubular dysfunction, resulting in acute and chronic kidney injury. Metabolomic and transcriptomic data from a murine model of Leptospira infection were analysed to determine whether metabolomic data from urine were associated with transcriptome changes relevant to kidney injury caused by Leptospira infection. Our findings revealed that 37 metabolites from the urine of L. interrogans-infected mice had significantly different concentrations than L. biflexa-infected and non-infected control mice. Of these, urinary L-carnitine and acetyl-L-carnitine levels were remarkably elevated in L. interrogans-infected mice. Using an integrated pathway analysis, we found that L-carnitine and acetyl-L-carnitine were involved in metabolic pathways such as fatty acid activation, the mitochondrial L-carnitine shuttle pathway, and triacylglycerol biosynthesis that were enriched in the renal tissues of the L. interrogans-infected mice. This study highlights that L-carnitine and acetyl-L-carnitine are implicated in leptospiral infection-induced kidney injury, suggesting their potential as metabolic modulators.

Implication of the IL-10-Expression Signature in the Pathogenicity of Leptospira-Infected Macrophages

Leptospirosis, an emerging infectious disease caused by pathogenic Leptospira spp., occurs in ecoregions with heavy rainfall and has public health implications. Macrophages are the major anti-Leptospira phagocytes that infiltrate the kidneys during renal leptospirosis, which is caused by leptospires residing in the renal tubules. The pathogenicity of Leptospira spp. in immune effector cells such as macrophages is not well understood. To evaluate this pathogenesis, we characterized and compared the transcriptome-wide alterations in macrophages infected with pathogenic and nonpathogenic Leptospira spp. Using transcriptome data and quantitative reverse transcription PCR analysis, at 2 h postinfection, the hypoxia-inducible factor-1α-dependent glycolysis pathway was implicated in pathogenic Leptospira-infected macrophages but not in nonpathogenic leptospiral infections. Immune-related biological processes were mostly activated in pathogenic Leptospira-infected macrophages, and flow cytometry investigations revealed that classically activated macrophages represent the predominant polarization status. At 24 h after infection, biological pathways associated with interleukin-10, IL-10, signaling the induction of macrophage tolerance, as well as higher levels of IL-10 mRNA and protein expression, were observed in nonpathogenic Leptospira-infected macrophages compared to in pathogenic leptospiral infection. Following leptospiral infection of macrophages, strong IL-10-expressing transcriptome signatures were observed following nonpathogenic leptospiral infection. The transcriptional programs generated in Leptospira-infected macrophages revealed an inflammatory milieu following the production of a critical anti-inflammatory cytokine, IL-10, which is implicated in controlling the pathogenicity of activated macrophages. These findings imply that IL-10-mediated anti-inflammatory responses and tolerance in activated macrophages induced by nonpathogenic Leptospira spp. infection reduce inflammation and tissue damage, thus providing a potential therapeutic target for leptospirosis. IMPORTANCE Activation of macrophages by Leptospira spp. infection is thought to be involved in the pathogenesis of leptospirosis. To evaluate the innate macrophage responses to Leptospira spp., specifically pathogenic versus nonpathogenic Leptospira spp., we characterized the entire transcriptome-wide alterations in infected macrophages. We showed that hypoxia-inducible factor-1α and immune-related pathways are activated in pathogenic leptospiral-infected macrophages. We confirmed the significantly high levels of IL-10-expressing signatures and tolerance in activated macrophages caused by nonpathogenic Leptospira infection. Furthermore, nonpathogenic leptospiral infections attenuated macrophage activation responses. These findings suggest a potential therapeutic strategy for the immune microenvironment caused by macrophage activation driven by IL-10 overexpression, which may contribute to regulating inflammation in leptospirosis.

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.

Peptidoglycan mediates Leptospira outer membrane protein Loa22 to toll-like receptor 2 for inflammatory interaction: a novel innate immune recognition

Leptospirosis is an overlooked zoonotic disease caused by pathogenic Leptospira depended on virulence of Leptospira and the host–pathogen interaction. Kidney is the major organ infected by Leptospira which causes tubulointerstitial nephritis. Leptospira outer membrane contains several virulence factors and an outer membrane protein A (OmpA) like protein (Loa22) is essential for virulence. Pull-down assays suggested that Loa22 was a potential Toll-Like Receptor 2 (TLR2) binding candidates from pathogenic Leptospira. Confocal microscopy was employed to observe the co-localization of TLR2 and Loa22-LPGN (Leptospira peptidoglycan) complexes. Atomic force microscopy (AFM), side-directed mutagenesis, and enzyme-linked immunosorbent assay (ELISA) were performed to investigate the affinity between rLoa22, LPGN, and TLR2. Real time PCR was applied to measure the cytokines expression. Downstream signal transduction components were verified by western blot to evaluate the gene regulations. Mutation of two Loa22 key residues (Asp¹²² and Arg¹⁴³) attenuated the affinities for LPGN. rLoa22-LPGN complexes were observed to co-localize with TLR2 and provoked inflammatory responses including CXCL8/IL8, hCCL2/MCP-1, and hTNF-α. Affinity studies suggested that Loa22-LPGN complexes elevated the affinity to TLR2 as compared to Loa22 protein. Downstream signals from TLR2 including p38, ERK, and JNK were regulated under rLoa22-LPGN complexes treatments. This study identified LPGN mediates interactions between Loa22 and TLR2 and induces downstream signals to trigger inflammatory responses. rLoa22-LPGN-TLR2 complexes reveal a novel binding mechanism for the innate immune system.

Escape of TLR5 Recognition by Leptospira spp.: A Rationale for Atypical Endoflagella

Leptospira (L.) interrogans are invasive bacteria responsible for leptospirosis, a worldwide zoonosis. They possess two periplasmic endoflagellae that allow their motility. L. interrogans are stealth pathogens that escape the innate immune recognition of the NOD-like receptors NOD1/2, and the human Toll-like receptor (TLR)4, which senses peptidoglycan and lipopolysaccharide (LPS), respectively. TLR5 is another receptor of bacterial cell wall components, recognizing flagellin subunits. To study the contribution of TLR5 in the host defense against leptospires, we infected WT and TLR5 deficient mice with pathogenic L. interrogans and tracked the infection by in vivo live imaging of bioluminescent bacteria or by qPCR. We did not identify any protective or inflammatory role of murine TLR5 for controlling pathogenic Leptospira. Likewise, subsequent in vitro experiments showed that infections with different live strains of L. interrogans and L. biflexa did not trigger TLR5 signaling. However, unexpectedly, heat-killed bacteria stimulated human and bovine TLR5, but did not, or barely induced stimulation via murine TLR5. Abolition of TLR5 recognition required extensive boiling time of the bacteria or proteinase K treatment, showing an unusual high stability of the leptospiral flagellins. Interestingly, after using antimicrobial peptides to destabilize live leptospires, we detected TLR5 activity, suggesting that TLR5 could participate in the fight against leptospires in humans or cattle. Using different Leptospira strains with mutations in the flagellin proteins, we further showed that neither FlaA nor Fcp participated in the recognition by TLR5, suggesting a role for the FlaB. FlaB have structural homology to Salmonella FliC, and possess conserved residues important for TLR5 activation, as shown by in silico analyses. Accordingly, we found that leptospires regulate the expression of FlaB mRNA according to the growth phase in vitro, and that infection with L. interrogans in hamsters and in mice downregulated the expression of the FlaB, but not the FlaA subunits. Altogether, in contrast to different bacteria that modify their flagellin sequences to escape TLR5 recognition, our study suggests that the peculiar central localization and stability of the FlaB monomers in the periplasmic endoflagellae, associated with the downregulation of FlaB subunits in hosts, constitute an efficient strategy of leptospires to escape the TLR5 recognition and the induced immune response.

Leptospirosis is an invasive infectious and systemic inflammatory disease

Pathogenic Leptospira species are the causative agents of leptospirosis, a world-spreading zoonotic infectious disease. The pathogens possess a powerful invasiveness by invading human body through mucosal/skin barriers, rapid entry into bloodstream to cause septicemia, diffusion from bloodstream into internal organs and tissues to cause aggravation of disease, and discharge from urine through renal tubules to form natural infectious sources. Leptospirosis patients present severe inflammatory symptoms such as high fever, myalgia and lymphadenectasis. Hemorrhage and jaundice are the pathological features of this disease. Previous studies revealed that some outer membrane proteins of Leptospira interrogans, the most important pathogenic Leptospira species, acted as adherence factors to binding to receptor molecules (fibronectin, laminin and collagens) in extracellular matrix of host cells. Collagenase, metallopeptidases and endoflagellum contributed to the invasiveness of L. interrogans. Except for lipopolysaccharide, multiple hemolysins of L. interrogans displayed a powerful ability to induce pro-inflammatory cytokines and hepatocyte apoptosis. vWA and platelet activating factor acetylhydrolase-like proteins from L. interrogans could induce severe pulmonary hemorrhage in mice. L. interrogans utilized cellular endocytic recycling and vesicular transport systems for intracellular migration and transcellular transport. All the research achievements are helpful for further understanding the virulence of pathogenic Leptospira species and pathogenesis of leptospirosis.

Leptospirosis as a risk factor for chronic kidney disease: A systematic review of observational studies

Background

Leptospirosis is a worldwide prevalent zoonosis and chronic kidney disease (CKD) is a leading global disease burden. Because of pathophysiological changes in the kidney, it has been suggested that these conditions may be associated. However, the extent of this interaction has not been synthetized. We aimed to systematically review and critically appraise the evidence on the association between leptospirosis and CKD.

Methodology/Principal findings

Observational studies with a control group were selected. Leptospirosis, confirmed with laboratory methods, and CKD also based on a laboratory assessment, were the exposures and outcomes of interest. The search was conducted in EMBASE, MEDLINE, Global Health, Scopus and Web of Science. Studies selected for qualitative synthesis were assessed for risk of bias following the Newcastle-Ottawa Scale. 5,981 reports were screened, and 2 (n = 3,534) were included for qualitative synthesis. The studies were conducted in Taiwan and Nicaragua; these reported cross-sectional and longitudinal estimates. In the general population, the mean estimated glomerular filtration rate (eGFR) was lower (p<0.001) in people testing positive for antileptospira antibodies (eGFR = 98.3) than in negative controls (eGFR = 100.8). Among sugarcane applicants with high creatinine, those who were seropositive had lower eGFR (mean difference: -10.08). In a prospective analysis, people with high antileptospira antibodies titer at baseline and follow-up, had worse eGFR (p<0.05).

Conclusion

Although the available evidence suggests there may be a positive association between leptospirosis and CKD, whereby leptospirosis could be a risk factor for CKD, it is still premature to draw conclusions. There is an urgent need for research on this association.

Leptospirosis is an infection that can affect the kidneys acutely, though it seems that even after the acute infection there could be risk of a long-term impaired kidney function. The evidence on this matter is sparse and limited, thus the need to comprehensively seek, synthetize and appraise the available scientific literature. In so doing, this work has found preliminary evidence that leptospirosis may be associated with impaired kidney function as per eGFR. This work and findings strongly reveal that more research is needed to quantify and characterize the long-term risk of CKD among those who had had leptospirosis infection. The raising burden of non-communicable diseases paired with a still non-negligible burden of communicable and neglected tropical diseases in low- and middle-income countries, deserve the synergism of these two broad fields for the benefit of patients and population health.