Schistosoma mansoni: anodic polysaccharide antigen in glomerular immune deposits of mice with unisexual infections

Schistosomal glomerulopathy and changes in the distribution of histological patterns of glomerular diseases in Bahia, Brazil

Distinct patterns of glomerular lesions, including membranoproliferative glomerulonephritis and focal segmental glomerulosclerosis, are associated with infection by Schistosoma mansoni or Schistosoma japonicum. Evidence suggests that immune complex deposition is the main mechanism underlying the different forms of schistosomal glomerulonephritis and that immune complex deposition may be intensified by portal hypertension. The relationship between focal segmental glomerulosclerosis and schistosomiasis remains poorly understood. A clinicopathologic classification of schistosomal glomerulopathies was proposed in 1992 by the African Association of Nephrology. In Brazil, mass treatment with oral medications has led to a decrease in the occurrence of schistosomal glomerulopathy. In a survey of renal biopsies performed in Salvador, Brazil, from 2003-2009, only 24 (4%) patients were identified as positive for S. mansoni infection. Among these patients, only one had the hepatosplenic form of the disease. Focal segmental glomerulosclerosis was found in seven patients and membranoproliferative glomerulonephritis was found in four patients. Although retrospective studies on the prevalence of renal diseases based on kidney biopsies may be influenced by many patient selection biases, a change in the distribution of glomerulopathies associated with nephrotic syndrome was observed along with a decline in the occurrence of severe forms of schistosomiasis.

Immunopathology of Schistosoma mansoni infection

Schistosomiasis mansoni is a chronic helminthic disease that affects about 100 million people in the tropics. The worms have a life span of 5 to 10 years, and they live in the mesenteric veins of the host. Lightly infected individuals are asymptomatic or manifest mild intestinal symptoms. Heavily infected individuals often develop severe morbidity with hepatosplenomegaly, sometimes with a fatal outcome. Morbidity is attributed to the strong humoral and T-cell-mediated host immune responses developed to a variety of parasite antigens and expressed as tissue inflammations. The immunopathology includes dermatitis, immune complex-mediated kidney disease, and, chiefly, T-cell-mediated granuloma formation and fibrosis around disseminated parasite eggs. This review describes the mechanisms of induction and expression of immunopathology in infected persons and experimental animals. Immunoregulatory mechanisms that modulate the enhanced immune responses and may ameliorate excessive morbidity are discussed.

Schistosoma mansoni: impaired clearance of model immune complexes consisting of circulating anodic antigen and monoclonal IgG1 in infected mice

The clearance of schistosome-specific model immune complexes (IC) consisting of circulating anodic antigen (CAA), a gut-associated excretory-secretory antigen, and radiolabeled monoclonal antibody (IgG1) was investigated in mice with a light and heavy Schistosoma mansoni infection and in noninfected control animals. The size analysis of the in vitro prepared and injected IC, as determined by density gradient centrifugation, revealed a wide peak at 11S. In infected animals the injected IC were cleared at a significantly lower rate than in control mice. This was attributed to a decreased uptake of IC by the liver in infected mice. In heavily infected mice, 30 min after injection of 11S IC, 8S, 11S, and greater than 11S IC were present in the serum, whereas only small 8S IC were detected in the serum of lightly infected animals and noninfected controls. Immune complexes were also present in the serum of heavily infected mice 30 min after injection of antibody and were detectable as 11S and greater than 11S IC. The importance of this study is twofold. First, these results show that schistosome-specific monoclonal antibodies can be used in the production of model immune complexes applicable in clearance studies. Second, our findings might be of importance when the possible pathogenicity of circulating IC in schistosomiasis is considered.

Ultrastructural localization of the circulating anodic antigen and the circulating cathodic antigen in the liver of mice infected with Schistosoma mansoni: a sequential study

The present study describes the ultrastructural localization of two important circulating schistosome antigens--the circulating anodic antigen (CAA) and the circulating cathodic antigen (CCA)--in livers of mice at various time intervals after infection with Schistosoma mansoni. For the demonstration of these antigens at the electron microscope level use was made of a direct, double immunogold labeling procedure, in which CAA-specific monoclonal antibodies, labeled with 5-nm gold particles, and CCA-specific monoclonal antibodies, labeled with 15-nm gold particles, were used. Both antigens were localized in granules and in inclusion bodies of Kupffer cells and granuloma macrophages and it was found that in these compartments the degree of 5- and 15-nm gold labeling increased with the duration of the infection. Sometimes gold particles were also encountered on the cell surface and in endocytotic vesicles of these cells, in endothelial cells, and in the space of Disse. From these data it was concluded that in the liver CAA and CCA were primarily accumulated in granules and inclusion bodies of Kupffer cells and granuloma macrophages. It is discussed whether at these locations both antigens are degraded by lysosomal enzymes and whether these antigens are complexed with antibodies.

Surface antigen detected by a Schistosoma mansoni monoclonal antibody in worm extracts and kidney deposits of infected mice and hamsters

Four monoclonal antibodies (MAbs) derived from a Schistosoma mansoni-infected mouse reacted against the tegument or the cell layer of the digestive tract of the adult worm. They also showed similar patterns of immunofluorescence staining when schistosomula were used as antigens. Two of the MAbs (4A10 and 4D3) recognized immune complexes deposited in the kidneys of infected mice and hamsters as detected by indirect and direct immunofluorescence reactions. When adsorbed to polystyrene beads, both MAbs allowed the quantitative detection of antigen by an enzyme immunoassay. 125I-labeled 4A10 binding to live schistosomula and corresponding inhibition assay ruled out the possibility that this binding could be through its Fc fragment. The same MAb detected an antigen migrating as an 80-kilodalton protein by Western blot analysis of soluble worm antigen preparation after sodium dodecyl sulfate-polyacrylamide gel electrophoresis. Use of MAb 4A10 may help to elucidate mechanisms of renal pathology and also be of value in the development of immunodiagnostic assays.

Unisexual murine schistosomiasis: portal hepatitis in subacute infections

Liver changes induced by unisexual male infection with S. mansoni were studied in mice during 2-20 weeks post-infection, in order to distinguish changes related to released worm substances from changes related to schistosome egg deposition. In subacute unisexual infection the venous wall appears as the target for inflammation which remains focal for a long time and affects limited segments of the main portal veins. Schistosomal pigment deposited in the lobule does not induce inflammatory or fibrogenic reactions.

Immunofluorescent localization of Schistosoma mansoni circulating cathodic antigen in tissues of infected mice using monoclonal antibody

In the present study the kinetics of the uptake and deposition of the major circulating cathodic antigen (CCA) of Schistosoma mansoni in liver, spleen, and kidney of S. mansoni infected Swiss mice was investigated in relation to the duration of infection and infection dose (50, 100, 200 cercariae). The presence of antigen was studied with a direct immunofluorescence reaction on frozen sections of the mouse organs, using a fluorescein isothiocyanate (FITC)-labelled mouse IgM monoclonal antibody recognizing a repeating epitope of CCA. CCA was demonstrable from 2 weeks post infection (p.i.) onwards in Kupffer cells in the liver, from 3-4 weeks p.i. onwards in macrophages in the marginal zones in the spleen and from 8 weeks p.i. onwards in kidney glomeruli. The immunofluorescence reactions on CCA in kidney glomeruli, however, remained relatively weak.

Presence of Schistosoma mansoni antigens in liver, spleen and kidney of infected mice: a sequential study

In the present study the kinetics of the uptake and deposition of Schistosoma mansoni antigens in liver, spleen and kidney of S. mansoni infected Swiss mice have been investigated in relation to duration of infection and infection dose (50, 100, 200 cercariae). The presence of antigen was studied with a direct immunofluorescence reaction on frozen sections of the organs, using a number of fluorescein isothiocyanate (FITC)-labeled antisera produced against various antigen preparations isolated from different life-cycle stages of the parasite. The presence of antigen was demonstrable with two of the antisera, directed against the circulating anodic antigen (CAA) and against total soluble egg antigen (SEA). CAA was demonstrable from 1 week post infection (p.i.) onwards in Kupffer cells in the liver, from 2-3 weeks p.i. onwards in macrophages in the marginal zones in the spleen and from 3 weeks onwards in kidney glomeruli. Immunofluorescence reactions on CAA in kidney glomeruli, however, were only weak positive until 12 weeks p.i., whereafter strong positive reactions were found. SEA was demonstrable from 5 weeks p.i. onwards in Kupffer cells in the liver and from 4 weeks p.i. onwards in macrophages of the spleen. In contrast to CAA, SEA was not detectable in kidney glomeruli.