RESUMEN
Patients chronically infected with Trypanosoma cruzi develop chronic Chagas' heart disease (cChHD). Their Ab response is suspected to be involved in the cardiac pathogenesis. Reactivity of serum Abs from these patients has been extensively studied but little is known about the diversity of the in vivo IgG repertoire. We analyzed 125 variable H chain (VH) genes and compared it to repertoires from healthy individuals, and patients with autoimmune processes and other infections. VH were from plasma cells isolated from heart tissue of three cChHD patients and from a Fab combinatorial library derived from bone marrow of another cChHD patient. The role of the parasite in shaping the Ab repertoire was assessed analyzing VH genes before and after panning against T. cruzi Ag. Among recovered VH genes, a significantly increased representation of VH4 was observed. Plasma cells at the site of cardiac infiltration showed an increased VH1 usage. CDR3 lengths were similar to the ones found in the healthy repertoire and significantly shorter than in other infections. VH derived from anti-T. cruzi Fab and plasma cells showed a higher proportion of hypermutated genes, 46.9% and 43.75%, respectively, vs 30.9% of the cChHD patient repertoire, pointing to the role of parasite Ags in the shaping of the humoral response in Chagas' disease. No histological evidence of germinal center-like structures was observed in heart tissue. In accordance, VH analysis of heart plasmocytes revealed no evidence of clonal B cell expansion, suggesting that they migrated into heart tissue from secondary lymphoid organs.
Asunto(s)
Anticuerpos Antiprotozoarios/genética , Cardiomiopatía Chagásica/inmunología , Reordenamiento Génico de Linfocito B/genética , Cadenas Pesadas de Inmunoglobulina/biosíntesis , Cadenas Pesadas de Inmunoglobulina/genética , Región Variable de Inmunoglobulina/biosíntesis , Región Variable de Inmunoglobulina/genética , Adulto , Secuencia de Aminoácidos , Anticuerpos Antiprotozoarios/biosíntesis , Antígenos de Protozoos/inmunología , Linfocitos B/inmunología , Linfocitos B/parasitología , Linfocitos B/patología , Cardiomiopatía Chagásica/parasitología , Cardiomiopatía Chagásica/patología , Enfermedad Crónica , Regiones Determinantes de Complementariedad/biosíntesis , Regiones Determinantes de Complementariedad/genética , Femenino , Humanos , Masculino , Persona de Mediana Edad , Datos de Secuencia Molecular , Hipermutación Somática de Inmunoglobulina/genética , Trypanosoma cruzi/inmunologíaRESUMEN
It is still unclear to what extent myocarditis-associated, chronic Chagas' heart disease is due to persisting Trypanosoma cruzi. In the present study, we have analyzed tissue samples from the hearts of three patients with this disease. In situ hybridization provided little evidence for the presence of intact T. cruzi even at sites of strong inflammation. Nevertheless, micromanipulation techniques detected remnants of both T. cruzi kinetoplast DNA and nuclear DNA. Trypanosoma cruzi DNA was also detected in single macrophages dissected directly from frozen heart tissue sections. Thus, this analysis demonstrates that T. cruzi kinetoplast DNA and nuclear DNA are widely dispersed in the heart tissue, although in low amounts. Since we rarely detected intact T. cruzi parasites during the chronic phase of Chagas' heart disease, we can exclude heart tissue as a major parasite reservoir.