i(3)so3-galactosylceramide and Chagas-Disease

American Trypanosomiasis or Chagas disease (ChD), a major problem that is still endemic in large areas of Latin America, is caused by

Topics: Animals; Chagas Disease; Glycoconjugates; Glycoproteins; Humans; Mice; Oligosaccharides; Protozoan Proteins; Sulfates; Sulfoglycosphingolipids; Trypanosoma cruzi

Increasing evidence suggests that in Chagas' disease chronic-phase pathology is autoimmune in nature. There are at least two nonexclusive explanations for the generation of autoimmunity in Chagas disease: a) infection with the parasite perturbs immunoregulation, leading to loss of tolerance for self-antigens; b) immune recognition of T. cruzi antigens is crossreactive with selected mammalian antigens, leading to autoimmunity (molecular mimicry). Through this latter mechanism, T. cruzi antigens that share epitopes with mammalian nervous tissue may drive autoreactive B- or T-cell clones to expand and cause autoimmune lesions in chronic chagasic patients. Several different antigens sharing this characteristic have been studied, as for example the 160-kDa flagellum-associated surface protein (Fl-160), which has a nervous tissue crossreactive epitope composed by twelve amino acids. Additionally, it has been demonstrated that a trypomastigote stage-specific 85kDa surface glycoprotein (Gp85) has terminal galactosyl(alpha 1-3)galactose terminal residues, which are reactive with chronic chagasic sera. Common glycolipid antigens have also been reported, as for example galactocerebroside, sulfogalactocerebroside and sulfoglucuronylcerebroside, all of them specifically present at high concentrations in mammalian nervous system and in T. cruzi trypomastigotes. Chronic chagasic patients produce elevated levels of antibodies against these three glycolipid antigens. They also do against terminal galactosyl(alpha 1-3)galactose residues present on several acid and neutral glycolipids common either to nervous system or parasite. These antibodies are powerful lytic for circulating T. cruzi trypomastigotes. Another common strongly immunogenic residues are galactosyl(alpha 1-2)galactose, galactosyl(alpha 1-6)galactose and galactofuranosyl(beta 1-3)mannose residues present on several glycoinositolphospholipids (GIPL), against which chronic chagasic patients have elevated levels of specific antibodies. In brief, very specific host-parasite relationships existing only in Chagas' disease may explain the particular peripheral nervous tissue damage seen in acute or chronic stages of this disease. This specificity could depend either on invasion of autonomic ganglia by T. cruzi trypomastigotes and modification of nervous cell surface structures by some of the several mechanisms of acquired molecular mimicry.

Topics: Amino Acid Sequence; Animals; Antibodies, Protozoan; Antigens, Protozoan; Autoantibodies; Autoantigens; Autoimmune Diseases; Carbohydrate Sequence; Chagas Disease; Chronic Disease; Cross Reactions; Galactose; Galactosylceramides; Glucose; Glycosylphosphatidylinositols; Molecular Sequence Data; Nerve Tissue Proteins; Protozoan Proteins; Sulfoglycosphingolipids; Trypanosoma cruzi

Sulphoglycosphingolipids, present on the surface of diverse cells, participate in the regulation of various cellular events. However, little is known about the structure and the role of sulphoglycosphingolipids in trypanosomatids. Herein, sulphated dihexosylceramide structures - composed mainly of sphingosine as the long chain base acylated with stearic acid - have been determined for the first time in Trypanosoma cruzi epimastigotes by UV-MALDI-TOF-MS analysis. Interestingly, inhibition ELISA assays using cruzipain as antigen and polyclonal rabbit antibodies specific for cruzipain, the major cysteine proteinase of T. cruzi, or for its C-terminal domain, have demonstrated (i) that sulphate epitopes are shared between cruzipain and sulphatides of T. cruzi, (ii) that cross-reactivity maps to the C-terminal domain and (iii) the existence of other antigenic determinants in the glycolipidic structures. These features provide evidence that sulphate groups are antigenic in sulphate-containing parasite glycoconjugates. Furthermore, IgG2 antibody levels inversely correlate with disease severity in chronic Chagas disease patients, suggesting that IgG2 antibodies specific for sulphated epitopes might be associated with protective immunity and might be considered as potential surrogates of the course of chronic Chagas disease.

Topics: Adult; Animals; Antiprotozoal Agents; Chagas Disease; Cross Reactions; Cysteine Endopeptidases; Enzyme-Linked Immunosorbent Assay; Female; Glycoconjugates; Humans; Immunoglobulin G; Male; Middle Aged; Protozoan Proteins; Rabbits; Spectrometry, Mass, Matrix-Assisted Laser Desorption-Ionization; Sulfoglycosphingolipids; Trypanosoma cruzi

We demonstrated that administration of interferon gamma (IFN-gamma) to pregnant rats conferred partial resistance in their offspring to further challenge with Trypanosoma cruzi. Because of the effects of IFN-gamma on macrophage activation and immunoglobulin isotype selection, offspring were now studied to ascertain whether this intervention modifies the in vitro replication of T. cruzi and nitric oxide (NO) production by peritoneal macrophages (PE), together with the anti-T. cruzi IgG isotypes. To evaluate the possibility of a detrimental effect of IFN-gamma, serum levels of anti-sulphatide autoantibodies were also investigated. Offspring were born to mothers undergoing one of the following procedures during gestation: treatment with recombinant rat IFN-gamma, 50,000 IU/rat, five times/week for 3 weeks, which was started on the day of mating; infection with 10(6) trypomastigotes of T. cruzi at 7, 14, and 21 days after mating plus IFN-gamma treatment as given to the former group; the same protocol except that physiological saline was injected instead of IFN-gamma; injection of physiological saline only. Offspring were challenged at weaning with a similar dose of T. cruzi, to constitute four groups of infected young, plus an additional group of age-matched uninfected rats born to control mothers. PE were harvested at day 7 postinfection (pi), exposed to parasites and further investigated for the replication of T. cruzi and NO production, whereas ELISA studies for measuring serum anti-T. cruzi IgG subclasses and anti-sulphatide autoantibodies were performed at day 30 pi. The number of intracellular parasites in PE was markedly decreased in young born to IFN-gamma-treated mothers, this not being accompanied by higher nitrite levels in culture supernatants. Offspring delivered by IFN-gamma-treated mothers showed no higher serum concentrations of anti-sulphatide autoantibodies, but exhibited a preferential synthesis of anti-T. cruzi IgG2b antibodies. This rat isotype is known to fix complement and constitutes the rat counterpart of IgG2a mouse immunoglobulins whose synthesis is favoured by IFN-gamma.

Topics: Animals; Antibodies, Protozoan; Chagas Disease; Female; Immunoglobulin G; Interferon-gamma; Macrophages; Nitric Oxide; Pregnancy; Pregnancy Complications, Parasitic; Rats; Recombinant Proteins; Sulfoglycosphingolipids; Trypanosoma cruzi; Weight Gain

Earlier studies in Trypanosoma cruzi-infected rats revealed an increased antibody activity against sulfatide, a specific constituent of both myelin sheaths of peripheral nerves and T. cruzi epimastigotes. To investigate further the characteristics of such anti-sulfatide antibodies, we analyzed their IgG isotypes as well as their ability to bind to homologous neural host structures. Antisulfatide IgG-enriched fractions were obtained from rats acutely infected with T. cruzi. Immunoglobulin isotypes were determined by an enzyme-linked immunosorbent assay (ELISA) method to show that IgG2a and, more significantly, IgG2b were the predominant isotypes of antisulfatide autoantibodies. Further immunofluorescence studies carried out in coronal sections of the rat forebrain revealed, in turn, that antisulfatide antibodies were capable of reacting with homologous neural tissues. Specific binding of these rat autoantibodies to sulfocerebroside on cell surfaces in vivo may in theory play some detrimental role, given the reported ability of rat IgG2b to fix complement or to mediate antibody-dependent cell-mediated cytotoxicity reactions.

Topics: Acute Disease; Animals; Antibody Specificity; Autoantibodies; Chagas Disease; Chronic Disease; Corpus Callosum; Female; Immunoglobulin G; Immunoglobulin Isotypes; Male; Prosencephalon; Rats; Rats, Inbred Strains; Sulfoglycosphingolipids

Earlier work indicated that Trypanosoma cruzi infection in pregnant rats decreased the amount of myocardial damage that developed in their chronically infected offspring. Given the suspected role of autoimmune mechanisms in the generation of chronic myocarditis, we evaluated whether this maternal intervention was likely to affect the synthesis of autoantibodies in infected young. Autoantibodies were investigated against molecules exhibiting cross-reactivity with T. cruzi antigens or not, that is cerebroside sulphate (sulphatide) and actin, respectively. Female '1' rats (75 days old) that had been mated with syngeneic sires were separated into two groups, one challenged with living trypomastigotes at 7, 14 and 21 days following mating, and the other one given physiologic saline at the same intervals. At the time of weaning, offspring were injected with 10(6)/T. cruzi to constitute two infected groups: young born to infected mothers (InMoTc) and young delivered by uninfected mothers (CoMoTc). Serum antibodies were investigated by ELISA at 30 and 60 days post-infection, which represents acute and chronic infection, respectively. T. cruzi infection was associated with the production of anti-sulphatide antibodies, but the phenomenon was significantly less evident in InMoTc young and virtually unnoticeable during their chronic infection. Unlike the anti-sulphatide results, levels of anti-actin antibodies showed no differences between CoMoTc and InMoTc rats when compared during acute or chronic infection. The decreased production of anti-sulphatide autoantibodies of InMoTc offspring may be due to a modification of the immune repertoire of offspring because of the contact with parasite antigens during ontogeny.

Topics: Actins; Animals; Antigens, Protozoan; Autoantibodies; Chagas Cardiomyopathy; Chagas Disease; Female; Male; Maternal-Fetal Exchange; Pregnancy; Pregnancy Complications, Parasitic; Rats; Sulfoglycosphingolipids; Trypanosoma cruzi

A natural anti-sulphatide antibody was found to be present in the serum of every normal individual studied. The reactivity of the antibody was assessed by its interaction with galactosylceramide-I3-sulphate. Antigen-antibody binding was strongly blocked by 1 mM heparin, dextran sulphate and chondroitin sulphate A, and by 5 mM chondroitin sulphate B. Antibodies avidly absorb to rabbit erythrocytes, but discretely to rat erythrocytes, suggesting that they are different from galactocerebroside antibodies. Elevated levels of sulphatide antibodies were present in all of 102 chronic Trypanosoma cruzi-infected patients studied, but not in other patients having cutaneous or visceral leishmaniasis, T. rangeli infection or several other protozoal, helminthic or mycotic infections. Interestingly, 100% of 40 dilated cardiomyopathy patients also have elevated levels of sulphatide antibodies. As T. cruzi is rich in galactocerebroside sulphate, it is proposed that in chagasic patients this glycolipid could act as an immunogen, inducing elevated titres of sulphatide antibodies, which could be important in the pathogenesis of cardiac or peripheral nerve symptoms.

Topics: Adolescent; Adult; Aged; Antibody Specificity; Autoantibodies; Cardiomyopathy, Dilated; Chagas Disease; Chronic Disease; Enzyme-Linked Immunosorbent Assay; Erythrocytes; Female; Helminthiasis; Humans; Immunoglobulins; Male; Middle Aged; Mycoses; Protozoan Infections; Sulfoglycosphingolipids