Immunoglobulin-A and the pathogenesis of schistosomal glomerulopathy

Diagnosis and management of complicated urogenital schistosomiasis: a systematic review of the literature

BACKGROUND

Currently, there are no standardized guidelines for the diagnosis or management of the complications of urogenital schistosomiasis (UGS). This systematic review of the literature aims to investigate the state of the art in reference to diagnostic approaches and the clinical management of this condition.

METHODS

A systematic review of literature published between January 1990 and January 2021 was conducted in the MEDLINE database, scoping for articles regarding diagnostic means or therapeutic options for the complications of UGS, namely obstructive uropathy, bladder cancer, abortion, ectopic pregnancy, infertility, kidney failure, urolithiasis and the need for invasive procedures. Relevant data were then extracted from the articles deemed eligible according to the inclusion criteria.

MAIN RESULTS

In total, 3052 articles were identified by the research query, of which 167 articles fulfilling inclusion criteria after title/abstract screening and full-text evaluation were included, 35% on both diagnostic and therapeutic aspects, and 51% on diagnosis and 14% on therapy. Ultrasound was the most frequently tool employed for the diagnosis of UGS complications showing a good performance. Concerning the management of hydronephrosis, the majority of available evidences came from community-based studies where universal treatment with praziquantel was used leading to decrease of prevalence of obstructive uropathy. Concerning studies on surgical procedures, laser endoureterotomy followed by stenting was mostly employed in adult patients leading to a crude cure rate of 60% (43 of 71 patients). In the case of severe hydronephrosis, surgery consisting of ureteral re-implantation showed excellent results with a crude cure rate of 98% (157 cured patients of 160 treated). Concerning bladder cancer, data on 93 patients with a clear diagnosis of UGS-related bladder were available reporting a variable and sometime combined approach based on disease stage. Available data on diagnosis and management of abortion, ectopic pregnancy, infertility, kidney failure, urolithiasis and the need for invasive procedures due to UGS are also presented.

CONCLUSIONS

The review produced a complete picture of the diagnostic and therapeutic options currently available for complicated UGS. These results can be useful both for guiding clinicians towards correct management and for tracing the direction of future research.

Aquaporin-2 and NKCC2 expression pattern in patients with hepatosplenic schistosomiasis

OBJECTIVE

Schistosoma mansoni infection is considered a public health problem. Glomerular involvement in schistosomiasis is a well-documented complication, especially in hepatosplenic schistosomiasis (HSS). However, renal tubular function is poorly understood. The aim of this study was to investigate, through urinary exosomes, tubular transporters functionally in HSS patients.

METHODS

Cross-sectional study of 20 HSS patients who had isolated exosomes from urine samples. Protease inhibitor was added in the urine samples who were immediately frozen at -80 °C for further exosomes isolation. After urine had thawed, urinary exosomes were obtained using extensive vortexing, centrifugation and ultracentrifugation steps of urine. Urinary transporters expression from exosomes was evaluated by western blot, including NHE3, AQP2 and NKCC2. Charge amounts for gel electrophoresis were adjusted by urinary creatinine concentration of each patient to avoid urinary concentration bias. All protein expression of HSS patients was relative to healthy controls.

RESULTS

The expression of aquaporin-2 (AQP2) was lower in HSS patients than in controls (46.8 ± 40.7 vs. 100 ± 70.2%, P = 0.03) and the expression of the NKCC2 co-transporter was higher (191.7 ± 248.6 vs. 100 ± 43.6%, P = 0.02).

CONCLUSIONS

The decrease of AQP2 and the increase of NKCC2 expression in HSS patients seem to be involved with the inability of urinary concentration in these patients. These data show renal tubular abnormalities in HSS patients without manifest clinical disease.

Glomerular Detection of Schistosomal Antigen by Immunoelectron Microscopy in Human Mansonian Schistosomiasis

Schistosomal antigens (S. mansoni) were detected in glomeruli of nine patients with nephropathy and nephrotic syndrome by immunoelectron microscopy. The criteria for patients' selection were presence of intestinal schistosomiasis and absence of any surgical or other medical diseases, particularly lupus erythematosus, syphilis, and hepatitis B and C, which could explain the renal disease. When examined by light microscopy, kidney biopsies showed type I membranoproliferative glomerulonephritis in four patients, focal segmental glomerulosclerosis in two, and mesangioproliferative glomerulonephritis, membranous glomerulonephritis, and minimal change disease in one each of the remaining three patients. Immunofluorescence showed mainly immunoglobulin G (IgG), IgM, and different complement components (C3, Clq) deposits, particularly in the mesangial area, in eight patients. All patients had gold-labeled schistosomal antigen deposits in their glomeruli, chiefly in mesangial cells and matrix, along the glomerular membrane, and occasionally in the cytoplasm of epithelial cells. Although membranous glomerulonephritis has been rarely described in association with schistosomiasis and minimal change disease may be occasionally caused by an infectious disease like syphilis, the absence of definite experimental models and epidemiologic data suggests that coincidental pathologies without causal relationship with schistosomiasis cannot be ruled out to explain these findings.

Renal function in hepatosplenic schistosomiasis--an assessment of renal tubular disorders

Background

Renal involvement in Schistosoma mansoni infection is not well studied. The aim of this study is to investigate the occurrence of renal abnormalities in patients with hepatosplenic schistosomiasis (HSS), especially renal tubular disorders.

Methods

This is a cross-sectional study with 20 consecutive patients with HSS followed in a medical center in Maceió, Alagoas, Brazil. Urinary acidification and concentration tests were performed using calcium chloride (CaCl₂) after a 12-h period of water and food deprivation. The biomarker monocyte chemoattractant protein 1 (MCP-1) was quantified in urine. Fractional excretion of sodium (FE_Na+), transtubular potassium gradient (TTKG) and solute-free water reabsorption (TcH₂O) were calculated. The HSS group was compared to a group of 17 healthy volunteers.

Results

Patients' mean age and gender were similar to controls. Urinary acidification deficit was found in 45% of HSS patients. Urinary osmolality was significantly lower in HSS patients (588±112 vs. 764±165 mOsm/kg, p = 0,001) after a 12-h period of water deprivation. TcH₂O was lower in HSS patients (0.72±0.5 vs. 1.1±0.3, p = 0.04). Urinary concentration deficit was found in 85% of HSS patients. The values of MCP-1 were higher in HSS group than in control group (122±134 vs. 40±28 pg/mg-Cr, p = 0.01) and positively correlated with the values of microalbuminuria and proteinuria.

Conclusions

HSS is associated with important kidney dysfunction. The main abnormalities found were urinary concentrating ability and incomplete distal acidification defect, demonstrating the occurrence of tubular dysfunction. There was also an increase in urinary MCP-1, which appears to be a more sensitive marker of renal damage than urinary albumin excretion rate.

Parasitic kidney disease: milestones in the evolution of our knowledge

Of the 342 parasites that infect humans, 20 are associated with kidney disease, yet of these, only schistosomes, plasmodia, filariae, and leishmanias are held responsible for significant clinical or epidemiologic impact. Reviewing the evolution of human knowledge for these parasites discloses a lot of similarities regarding their discovery, patterns of kidney injury, and pathogenic mechanisms. From a historical perspective, our relevant information may be classified into 4 phases: (1) disease documentation in ancient and medieval scripts as far back as 2000-3000 bce; (2) discovery of the parasites, their life cycles, and clinical correlates by European clinicians working in African and Asian colonies during the second half of the 19th century; (3) discovery and characterization of the renal manifestations of monoparasitic infections during the second half of the 20th century; and (4) recognition of the confounding effects of coinfection with bacteria, viruses, or other parasites. The spectrum of respective kidney diseases extends all the way from acute kidney injury to glomerulonephritis, amyloidosis, urologic disorders, and malignancy. Discovery of the common immunopathogenetic host response to parasitic infections has provided a knowledge core that explains the similarities, diversities, and interactions with regard to kidney injury.

Urinary schistosomiasis: review

In this review, the clinical manifestations of urinary schistosomiasis are displayed from a pathogenetic perspective. According to the prevailing host’s immune response profile, urinary schistosomiasis may be broadly categorized into cell-mediated and immune-complex-mediated disorders. The former, usually due to Schistosoma haematobium infection, are attributed to the formation of granulomata along the entire urinary tract. As they heal with excessive fibrosis, they may lead to strictures, calcifications and urodynamic abnormalities. The main impact is lower urinary, the site of heaviest ovi-position. Secondary bacterial or viral infection is common, any may be incriminated in secondary stone formation of the development of bladder malignancy. Immune-complex mediated lesions are usually associated with hepatosplenic schistosomiasis due to Schistosoma mansoni infection. Circulating complexes composed of schistosomal gut antigens and different classes of immunoglobulins deposit in the kidneys leading to several patterns of glomerular pathology. The latter have been categorized under six classes based on the histological and immunofluorescence profile. These classes have been linked to respective clinical manifestations and depend on the stage of evolution of the host’s immune response, extent of associated hepatic fibrosis and co-infection with salmonella or hepatitis C. Secondary amyloidosis develops in 15% of such patients, representing a critical impairment of macrophage function. Conclusion: The wide clinicopathological spectrum of urinary schistosomiasis mirrors the evolution of the host’s immune response according to chronicity of infection, bacterial or viral co-infection and, in the case of glomerulonephritis, to the extent of hepatic co-morbidity.

Schistosoma hematobium-associated glomerulopathy

Schistosomiasis is the second most devastating tropical parasitic disease worldwide and is responsible for many urological complications. However, glomerular injury is a rare complication mainly described with Schistosoma mansoni. We report a case of membranoproliferative glomerulonephritis (MPGN) associated with Schistosoma hematobium infection in a young Senegalese boy living in a rural area. Clinical presentation was with steroid-resistant with nephrotic syndrome. Renal biopsy showed type 1 MPGN with the presence of S. hematobium eggs surrounded by a gigantocellular granuloma. Despite therapy with antihelminthic and immunosuppressive drugs, evolution was characterized by progression to end-stage renal disease over 1 year. More efforts should be made on the prevention and early detection of schistosomiasis among at-risk populations.

Characterization of antibody responses to the Sj23 antigen of Schistosoma japonicum after infection and immunization

Sj23, a member of the tetraspanin protein family, is a 23-kDa surface-exposed protein of Schistosoma japonicum and expressed in all infective parasite stages, which has been regarded as a potential candidate in vaccine development for schistosomiasis. In this study, we found that, in the BALB/c mouse model, Sj23 elicited rapid humoral responses after parasite infection and the dominant antibodies were of IgG2a subclass. Immunization with Sj23 by priming with recombinant SFV RNA virus particles followed by a boost with recombinant protein also generated strong IgG2a responses which did not provide protection against challenge with cercariae. Our data indicated that one of the functions of Sj23 of S. japonicum is to facilitate parasite immune regulation. Sj23 antigen-based vaccine may require strong adjuvant that can drive IgG1 responses which are more critical in resistance to helminth infection.

Intestinal schistosomiasis caused by both Schistosoma intercalatum and Schistosoma mansoni

A case is presented of intestinal schistosomiasis due to both Schistosoma intercalatum and Schistosoma mansoni in a 30-year-old man from Senegal with discussion of diagnostic approach, species identification and determination of the effect of treatment. The patient was admitted to hospital for investigation of renal failure, arterial hypertension and hypereosinophilia. Repeated stool examinations for ova and parasites were negative. Ultrasonography (US) and computed tomography (CT) of the abdomen showed no abnormalities. US of the urinary tract showed kidneys of borderline size with increased echogenicity. Cystoscopy and histopathological examination of bladder biopsy specimens were normal. Flexible colonoscopy revealed numerous nodular lesions in the rectosigmoid region and a few similar lesions in the transverse colon, the histopathological examination of which showed deposition of Schistosoma ova with granuloma formation. Examination of multiple crush biopsy specimens from the rectosigmoid region revealed numerous granulomas formed around Schistosoma eggs which had a terminal spine and were identified as S. intercalatum (longer than Schistosoma haematobium and with a slightly curved terminal spine) and a very few S. mansoni eggs. Crush biopsies from the lesions in the transverse colon showed only S. mansoni eggs. In conclusion, the examination of multiple crush biopsy specimens is a very sensitive and specific technique for species identification of Schistosoma, especially in mixed infections, and for defining the location and extent of the granulomas evoked by each species.

Anisakis simplex allergy and nephrotic syndrome

BACKGROUND

Anisakis simplex is a helmintic parasite of fish and shellfish that can induce in humans, after consumption, an immunoallergic response with multiorganic affectation, especially cutaneous (urticaria and angioedema), gastrointestinal and anaphylactic symptoms. Nephrotic syndrome can be produced by helmintic infection, especially schistosomiasis.

OBJECTIVE

To report the unusual case of nephrotic syndrome associated to an allergic response to A. simplex.

METHODS

A 60-year-old woman suffered from nephrotic syndrome three weeks after a generalized urticaria, angioedema and nauseas episode, following a raw anchovy's ingestion. Etiological study of nephrotic syndrome and urticaria/angioedema, cutaneous test, serum total and specific IgE determination, IgE-immunoblotting, and HLA typing were performed for diagnostic evaluation.

RESULTS

Prick-test with A. simplex extract was positive. It was observed a significance increase of total IgE to the three weeks of anchovy's ingestion and then it diminished progressively. Specific IgE to A. simplex was > 100 UI/ml. Immunoblotting to A. simplex, revealed the existence of IgE-binding proteins with molecular mass ranging from 20 kDa to 99 kDa. Class I HLA expressed by the patient was type HLA-B12. Other secondary causes of nephrotic syndrome were carefully ruled out.

CONCLUSIONS

These data suggest, for the first time, the association between allergy to A. simplex and nephrotic syndrome.

Pathology of renal diseases in the tropics

Renal diseases unique to the tropics are those that occur in association with infectious diseases including dengue hemorrhagic fever, typhoid fever, shigellosis, leptospirosis, lepromatous leprosy, malaria, opisthorchiasis, and schistosomiasis. These renal complications can be classified on the basis of their clinical and pathologic characteristics into acute transient reversible glomerulonephritis, chronic progressive irreversible glomerulonephritis, amyloidosis, and acute renal failure (ARF) resulting from acute tubular necrosis, acute tubulointerstitial nephritis, and thrombotic microangiopathy. Certain primary glomerular diseases including immunoglobulin (Ig) M nephropathy and focal segmental and global glomerulosclerosis are prevalent in some tropical countries. Renal complications of venomous snakebites also are common in the tropics. This article discusses and summarizes important works in the literature in respect to the clinical syndromes, pathologic features, and pathogenesis of tropical renal diseases both in humans and experimental animal models.

Nephropathy associated with animal, plant, and chemical toxins in the tropics

Widespread human exposure to a variety of drugs, chemicals, and biologic products and recent awareness of their toxic manifestations has led to the recognition of toxic nephropathy as an important segment of renal disease in the tropical countries. Tropical nephrotoxins are distinctly different from those seen in the rest of the world and are derived from local fauna and flora or plant and chemical sources. The spectrum of exposure varies from country to country and even from community to community, depending on variations in the distribution of local plants and animal species and prevalent social practices. Acute renal failure (ARF), either alone or in association with liver failure, neurologic abnormalities, metabolic acidosis, disseminated intravascular coagulation, or pulmonary infections is the most common form of presentation. Traditional medicines prescribed by witch doctors (traditional healers) constitute a special class of nephrotoxins among several communities in Africa and Asia. The prevalence of nephropathy caused by traditional medicines is directly related to a combination of ignorance, poverty, lack of medical facilities, lax legislation, and widespread belief in indigenous systems of medicine in rural areas. These medicines are a mix of herbs and unknown chemicals administered orally or as enemas. Clustering of cases after exposure to a particular agent suggests the possibility of a toxic insult. Common animal nephrotoxins are venoms of viper snakes, sea snakes, stinging insects, and raw gallbladder and bile of carp and sheep. Botanical nephrotoxins are encountered both in common edible plants (djenkol beans, mushrooms) and medicinal herbs (impila, cat's claw). Mistaken identification of medicinal herbs by untrained workers and even deliberate trials of toxic substitutes derived from plants frequently lead to renal disease, the most commonly reported being the Chinese herbal nephropathy. Nephrotoxicity caused by chemicals can be secondary to accidental occupational exposure in industrial work places (eg, chromic acid), or after suicidal or homicidal use (eg, copper sulphate, ethylene dibromide, ethylene glycol). Late presentation and multiorgan dysfunction are associated with a high mortality. A high index of suspicion, careful history taking, and an awareness of local practices are essential for proper diagnosis and management of toxic nephropathies in the tropics.