Visceral leishmaniasis-associated nephropathy in hospitalised Brazilian patients: new insights based on kidney injury biomarkers

Serum and urinary monocyte chemoattractant protein-1 as markers of inflammation and renal damage in dogs with naturally occurring leishmaniosis

BACKGROUND

Renal disease in canine leishmaniosis is of great importance owing to increased risk of mortality. In human visceral leishmaniosis, monocyte chemoattractant protein-1 (MCP-1) has been used as a marker of renal damage and inflammation. The purpose of this study was first to determine the serum MCP-1 and urinary MCP-1-to-creatinine ratio (uMCP-1/Cr) in healthy dogs and dogs with leishmaniosis at diagnosis, and second to determine whether these markers can differentiate disease severity at diagnosis.

METHODS

In total, 19 healthy seronegative dogs and 38 dogs with leishmaniosis were included in the study. Dogs with leishmaniosis were classified as LeishVet clinical staging and as International Renal Interest Society (IRIS) staging. Serum and urinary MCP-1 concentrations were measured with an enzyme-linked immunosorbent assay. A receiver operating characteristic (ROC) curve determined disease severity at diagnosis between two LeishVet groups (Stage II versus stage III and IV).

RESULTS

Dogs in Leishvet stages IIb, III, and IV had a median serum MCP-1 and uMCP-1/Cr concentration higher than healthy dogs (P < 0.0001). No statistical differences were found in serum MCP-1 and uMCP-1/Cr between dogs in LeishVet stage IIa and healthy dogs. The dogs in LeishVet stage IV had significantly higher serum MCP-1 and uMCP-1/Cr compared with the dogs in LeishVet stage IIa (P < 0.0001). Serum MCP-1 and uMCP-1 were significantly higher in dogs in IRIS stage I and II + III + IV compared with healthy dogs. Dogs stage II + III + IV of IRIS had a significantly higher serum MCP-1 compared with dogs in IRIS stage I (P < 0.0001). The area under the ROC curve for serum MCP-1 was 0.78 [95% confidence interval (CI) 0.64-0.93] and for uMCP-1/Cr it was 0.86 (95% CI, 0.74-0.99). The optimal cutoff value for serum MCP-1 and uMCP-1/Cr was 336.85 pg/ml (sensitivity of 79% and specificity of 68%) and 6.89 × 10-7 (sensitivity of 84% and specificity of 79%), respectively.

CONCLUSIONS

Serum MCP-1 and uMCP-1/Cr are increased in dogs with leishmaniosis compared with healthy dogs, suggesting the presence of inflammation and renal injury. Serum MCP-1 and uMCP-1/Cr were more elevated in the advanced stages of the disease compared with the moderate stages and, therefore, can be markers of the severity of the disease process.

A link between circulating immune complexes and acute kidney injury in human visceral leishmaniasis

Visceral leishmaniasis (VL) is an infectious disease caused by Leishmania infantum. Clinically, VL evolves with systemic impairment, immunosuppression and hyperactivation with hypergammaglobulinemia. Although renal involvement has been recognized, a dearth of understanding about the underlying mechanisms driving acute kidney injury (AKI) in VL remains. We aimed to evaluate the involvement of immunoglobulins (Igs) and immune complexes (CIC) in the occurrence of AKI in VL patients. Fourteen VL patients were evaluated between early treatment and 12 months post-treatment (mpt). Anti-Leishmania Igs, CIC, cystatin C, C3a and C5a were assessed and correlated with AKI markers. Interestingly, high levels of CIC were observed in VL patients up to 6 mpt. Concomitantly, twelve patients met the criteria for AKI, while high levels of cystatin C were observed up to 6 mpt. Plasmatic cystatin C was positively correlated with CIC and Igs. Moreover, C5a was correlated with cystatin C, CIC and Igs. We did not identify any correlation between amphotericin B use and kidney function markers in VL patients, although this association needs to be further explored in subsequent studies. Our data reinforce the presence of an important renal function impairment during VL, suggesting the involvement of Igs, CIC, and C5a in this clinical condition.

From Infection to Death: An Overview of the Pathogenesis of Visceral Leishmaniasis

Kala-azar, also known as visceral leishmaniasis (VL), is a disease caused by Leishmania infantum and L. donovani. Patients experience symptoms such as fever, weight loss, paleness, and enlarged liver and spleen. The disease also affects immunosuppressed individuals and has an overall mortality rate of up to 10%. This overview explores the literature on the pathogenesis of preclinical and clinical stages, including studies in vitro and in animal models, as well as complications and death. Asymptomatic infection can result in long-lasting immunity. VL develops in a minority of infected individuals when parasites overcome host defenses and multiply in tissues such as the spleen, liver, and bone marrow. Hepatosplenomegaly occurs due to hyperplasia, resulting from parasite proliferation. A systemic inflammation mediated by cytokines develops, triggering acute phase reactants from the liver. These cytokines can reach the brain, causing fever, cachexia and vomiting. Similar to sepsis, disseminated intravascular coagulation (DIC) occurs due to tissue factor overexpression. Anemia, hypergammaglobulinemia, and edema result from the acute phase response. A regulatory response and lymphocyte depletion increase the risk of bacterial superinfections, which, combined with DIC, are thought to cause death. Our understanding of VL's pathogenesis is limited, and further research is needed to elucidate the preclinical events and clinical manifestations in humans.

Subclinical signs of podocyte injury associated with Circulating Anodic Antigen (CAA) in Schistosoma mansoni-infected patients in Brazil

BACKGROUND

The long-term effects of schistosomiasis on the glomerulus may contribute to the development of chronic kidney disease. This study aimed to investigate baseline Schistosoma mansoni-Circulating Anodic Antigen (CAA) levels and their association with kidney biomarkers related to podocyte injury and inflammation in long-term follow-up after praziquantel (PZQ) treatment.

METHODS

Schistosoma infection was diagnosed by detecting CAA in urine using a quantitative assay based on lateral flow using luminescent up-converting phosphor reporter particles. A cutoff threshold of 0.1 pg/mL CAA was used to diagnose Schistosoma infection (baseline) in a low-prevalence area in Ceará, Northeast, Brazil. Two groups were included: CAA-positive and CAA-negative individuals, both of which received a single dose of PZQ at baseline. Urinary samples from 55 individuals were evaluated before (baseline) and at 1, 2, and 3 years after PZQ treatment. At all time points, kidney biomarkers were quantified in urine and adjusted for urinary creatinine levels.

RESULTS

CAA-positive patients had increased baseline albuminuria and proteinuria and showed greater associations between kidney biomarkers. CAA levels correlated only with Vascular Endothelial Growth Factor (VEGF) (podocyte injury) levels. Increasing trends were observed for malondialdehyde (oxidative stress), monocyte chemoattractant protein-1 (inflammation marker), and VEGF. In the follow-up analysis, no relevant differences were observed in kidney biomarkers between the groups and different periods.

CONCLUSIONS

S. mansoni-infected individuals presented subclinical signs of glomerular damage that may reflect podocyte injury. However, no causal effect on long-term renal function was observed after PZQ treatment.

Kidney injury biomarkers and parasitic loads of Schistosoma mansoni in a highly endemic area in northeastern Brazil

Schistosomiasis affects approximately 240 million people worldwide. In Brazil, it is estimated that 1.5 million people are infected with Schistosoma mansoni and up to 15% of diagnosed individuals develop kidney damage. Renal involvement in schistosomiasis mansoni is characterized by glomerular lesions, with a high incidence, especially in chronically infected patients living in areas of high endemicity. Renal damage occurs slowly and is often asymptomatic, with a long-term manifestation of chronic kidney disease, with progressive loss of kidney functions, and early detection of subclinical kidney disease is of great importance. The aim of this study was to investigate kidney damage in patients infected with S. mansoni through urinary biomarkers of kidney injury and their association with the different parasite loads found. The patients were divided into two groups based on the diagnosis of infection by S. mansoni by the Kato-Katz and IgG-ELISA-SEA method: group of individuals infected by S. mansoni, Kato-Katz positive (PG); and group of individuals not infected by S. mansoni, Kato-Katz-negative (NG). Urinary creatinine and albuminuria were determined by immunoturbidimetry and proteinuria by the colorimetric method. The urinary biomarkers of podocyte injury (VEGF and Nephrin) and glomerular inflammation (MCP-1) were quantified by immunoassay and expressed by the urinary creatinine ratio. Urinary VEGF showed significantly higher levels in PG compared to NG (p = 0.004), increasing at all intensities of infection including low parasite load (p = 0.020). Our results show increased signs of podocyte damage in patients with schistosomiasis mansoni regardless of the parasite load, evidenced by increased urinary VEGF levels. However, further studies are needed since data related to schistosomiasis glomerulopathy and its association with new urinary biomarkers of kidney injury are scarce in the literature.

Kidney complications of parasitic diseases

Parasitic agents have been known to cause human disease since ancient times and are endemic in tropical and subtropical regions. Complications of parasitic diseases, including kidney involvement, are associated with worse outcomes. Chagas disease, filariasis, leishmaniasis, malaria and schistosomiasis are important parasitic diseases that can damage the kidney. These diseases affect millions of people worldwide, primarily in Africa, Asia and Latin America, and kidney involvement is associated with increased mortality. The most common kidney complications of parasitic diseases are acute kidney injury, glomerulonephritis and tubular dysfunction. The mechanisms that underlie parasitic disease-associated kidney injury include direct parasite damage; immunological phenomena, including immune complex deposition and inflammation; and systemic manifestations such as haemolysis, haemorrhage and rhabdomyolysis. In addition, use of nephrotoxic drugs to treat parasitic infections is associated with acute kidney injury. Early diagnosis of kidney involvement and adequate management is crucial to prevent progression of kidney disease and optimize patient recovery.

Real Time PCR-based diagnosis of human visceral leishmaniasis using urine samples

Diagnosis of visceral leishmaniasis (VL) through the detection of its causative agents namely Leishmania donovani and L. infantum is traditionally based on immunochromatographic tests, microscopy of bone marrow, spleen aspirates, liver or lymph node and differential diagnosis. While the first process has low specificity, the later one carries the risk of fatal hemorrhage. Over the last decade, multiple Polymerase Chain Reaction (PCR) based diagnosis has been developed using blood and urine sample with a varying degree of sensitivity and specificity, an issue worth improving for precision diagnosis. Earlier, we reported a PCR-based diagnosis of L. donovani in peripheral blood using a novel set of PCR primers with absolute specificity. Using the same set of primers and PCR conditions, here we describe diagnosis of L. donovani from urine, for a non-invasive, rapid and safe diagnosis. Diagnosis of VL was carried out using urine samples collected from clinically diagnosed VL patients (n = 23) of Bangladesh in Real Time PCR. Test results were validated by comparing blood samples from the same set of patients. Sensitivity and specificity of this diagnosis was analyzed using retrospective bone marrow samples, collected earlier from confirmed VL patients (n = 19). The method showed 100% sensitivity in detecting L. donovani in urine and corresponding blood and retrospective bone marrow samples, as well as 100% specificity in control groups. A Real Time PCR-based molecular detection system using urine sample is hereafter presented what could be a, non-invasive approach for VL detection with precision and perfection.

Kidney injury molecule-1 and urinary gamma-glutamyl transferase as biomarkers of acute kidney injury in cats

OBJECTIVES

To evaluate the concentration of kidney injury molecule-1 and activity of urinary gamma-glutamyl transferase in cats with urethral obstruction and healthy cats.

MATERIALS AND METHODS

Blood and urine samples were collected from a group of 15 healthy cats (control group) and a group of 20 cats with urethral obstruction at presentation, and 24 hours and 7 days after unblocking the obstruction. The serum creatinine, urinary creatinine and urinary gamma-glutamyl transferase were measured by spectrophotometry and kidney injury molecule-1 by the sandwich enzyme-linked immunosorbent assay.

RESULTS

On presentation, cats with obstruction had serum creatinine concentration and urinary gamma-glutamyl transferase index higher than healthy cats (mean difference 544 μmol/L, 95% confidence intervals 222 to 865 μmol/L, and 0.0022 U/μmol-uCre, 0.00043 to 0.0039 U/μmol-uCre, respectively), urine creatinine concentration lower (mean difference 25,624 µmol/L, 17,329 to 33,919 µmol/L), and no significant difference in the kidney injury molecule-1/urinary creatinine ratio (mean difference 13 pg/μmol-uCre, -33 to 59 pg/μmol-uCre). In the group of cats with urinary obstruction, over time serum creatinine decreased, urine creatinine increased, urinary gamma-glutamyl transferase index did not change significantly, and kidney injury molecule-1/urinary creatinine ratio increased.

CLINICAL SIGNIFICANCE

Cats with post-renal obstruction and potential intrinsic renal damage had higher urinary gamma-glutamyl transferase index than healthy cats at the time of presentation and showed increase in kidney injury molecule-1/urinary creatinine ratio over time.

Potential Biomarkers in Diagnosis of Renal Acanthamoebiasis

Recent studies indicate that Acanthamoeba spp. may play a significant role in kidney dysfunction. The aim of the study was to examine the levels of kidney injury molecule 1 (KIM-1), neutrophil gelatinase-associated lipocalin (NGAL), and monocyte chemotactic protein 1 (MCP-1), as well as an activity of matrix metalloproteinases 2 and 9 (MMP-2 and MMP-9, respectively) in the kidneys of immunocompetent and immunosuppressed mice infected with Acanthamoeba spp. The levels of KIM-1, NGAL, and MCP-1 were analyzed by enzyme-linked immunosorbent assay (ELISA), and the activity of MMPs was determined by gelatin zymography. The elevated KIM-1 level was found in the kidneys of immunocompetent mice at the beginning of Acanthamoeba spp. infection. In the immunosuppressed mice, the KIM-1 level was statistically different. The statistically decreased NGAL level was found in the kidneys of immunocompetent mice compared to the uninfected mice. In the immunocompromised mice, we found statistically significant differences in MCP-1 levels between the uninfected and infected groups. There was an increase in the expression of both MMP-2 and MMP-9 in the kidneys of immunocompetent and immunosuppressed mice infected with Acanthamoeba spp. compared to the uninfected mice. The results indicate that KIM-1, NGAL, MCP-1, MMP-2, MMP-9, and MMP-9/NGAL might be promising biomarkers of renal acanthamoebiasis.

Pathomechanisms in the Kidneys in Selected Protozoan Parasitic Infections

Leishmaniasis, malaria, toxoplasmosis, and acanthamoebiasis are protozoan parasitic infections. They remain important contributors to the development of kidney disease, which is associated with increased patients' morbidity and mortality. Kidney injury mechanisms are not fully understood in protozoan parasitic diseases, bringing major difficulties to specific therapeutic interventions. The aim of this review is to present the biochemical and molecular mechanisms in kidneys infected with Leishmania spp., Plasmodium spp., Toxoplasma gondii, and Acanthamoeba spp. We present available mechanisms of an immune response, oxidative stress, apoptosis process, hypoxia, biomarkers of renal injury in the serum or urine, and the histopathological changes of kidneys infected with the selected parasites. Pathomechanisms of Leishmania spp. and Plasmodium spp. infections have been deeply investigated, while Toxoplasma gondii and Acanthamoeba spp. infections in the kidneys are not well known yet. Deeper knowledge of kidney involvement in leishmaniasis and malaria by presenting their mechanisms provides insight into how to create novel and effective treatments. Additionally, the presented work shows gaps in the pathophysiology of renal toxoplasmosis and acanthamoebiasis, which need further research.

Continuous hypergammaglobulinemia and proteinuria after the recovery of the visceral Leishmaniasis: a case report

BACKGROUND

Kidney involvement of visceral Leishmaniasis is previously reported, but knowledge is limited. Hypergammaglobulinemia is common in visceral leishmaniasis patients. Whether hypergammaglobulinemia after leishmaniasis depletion can cause kidney injury is not well reported yet.

CASE PRESENTATION

We reported a patient who recovered from visceral Leishmaniasis but showed persistent hypergammaglobulinemia and elevated urinary protein. Kidney biopsy showed glomerular hypertrophy with mild segmental mesangial proliferation without tubulointerstitial involvement in light microscopy. No immune complex deposit was found in the mesangial area by neither immunofluorescent staining nor electronic microscope. Increased lysosomes were observed in proximal tubules by electronic microscope. Valsartan was administered to decrease urinary protein, and no immune-suppressive therapy was added. The urinary protein and serum IgG level gradually dropped, and serum creatinine level remained stable during three- month follow up.

CONCLUSIONS

Hypergammaglobulinemia is unlikely to cause renal structural or functional damage in the short term. Angiotensin blockade significantly reduced urine protein, with a minor effect on IgG elimination.

Kidney biomarkers in tropical infections: an update

Neglected tropical diseases affect over 1 billion people, and cause 170,000 deaths each year. They result in disability, stigma and disfigurement, and also push families into poverty. Tropical infections can involve the kidney, presenting as a wide variety of ways, varying from transient urinary abnormalities to severe acute kidney injury (AKI). It is important to assess renal function in patients with tropical infections for earlier detection of AKI, appropriate treatment and prevention of Chronic Kidney Disease (CKD) outcome in some of them. There was an exponential increase in research on new kidney biomarkers that were earlier and specific for renal damage but few in the scope of tropical infections. In this review, we focus on kidney biomarkers that are being studied in some of the most prevalent tropical infections such as visceral leishmaniasis, leptospirosis, malaria, schistosomiasis and leprosy. Further studies are needed to evaluate the usefulness of renal biomarkers in the early diagnosis of renal diseases associated with tropical infections.

Novel kidney injury biomarkers in tropical infections: a review of the literature

Tropical diseases are mainly found in the tropical regions of Asia, Africa and Latin America. They are a major Public Health problem in these regions, most of them are considered neglected diseases and remain as important contributors to the development of AKI (Acute Kidney Injury), which is associated with increased patients' morbidity and mortality. In most countries, kidney disease associated to tropical diseases is attended at health services with poor infrastructure and inadequate preventive measures. The long-term impacts of these infections on kidney tissue may be a main cause of future kidney disease in these patients. Therefore, the investigation of novel kidney injury biomarkers in these tropical diseases is of utmost importance to explain the mechanisms of kidney injury, to improve their diagnosis and prognosis, as well as the assessment to health systems by these patients. Since 2011, our group has been studying renal biomarkers in visceral and cutaneous leishmaniasis, schistosomiasis, leptospirosis and leprosy. This study has increased the knowledge on the pathophysiology of kidney disease in the presence of these infections and has contributed to the early diagnosis of kidney injury, pointing to glomerular, endothelial and inflammatory involvement as the main causes of the mechanisms leading to nephropathy and clinical complications. Future perspectives comprise establishing long-term cohort groups to assess the development of kidney disease and the patients' survival, as well as the use of new biomarkers such as urinary exosomes to detect risk groups and to understand the progression of kidney injuries.

Urine as a promising sample for Leishmania DNA extraction in the diagnosis of visceral leishmaniasis - a review

Visceral leishmaniasis is a serious and debilitating infection with high fatality rate in tropical and subtropical countries. As clinical symptoms of visceral leishmaniasis are not so specific, confirmatory diagnostic methods with high sensitivity and specificity are needed. Noninvasive methods have been developed using urine as a clinical sample for visceral leishmaniasis diagnosis. In fact, there is a clear correlation between kidney impairment and Leishmania DNA in urine. However, it has been proved that Leishmania nucleic acid may also be isolated from patients without any sign of renal involvement. Even though urine has become a promissing biological sample, it is still not widely used due to several issues, such as (i) incomprehension of the whole renal pathophysiology process in visceral leishmaniasis, (ii) presence of many amplification inhibitors in urine, and (iii) lack of an efficient urinary DNA extraction method. In this article, we performed a literature review to bring a new perspective for Leishmania DNA isolation in urine.