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There is common agreement that fibromyalgia (FM) is an extremely heterogeneous entity. Patients differ in their clinical symptoms, endocrine and immune parameters. In this study we evaluated endocrine and immunological features of distinct subsets of FM patients. In contrast to previous attempts to identify subsets of FM patients, based solely on their psychological and cognitive features, herein we propose to separate FM patients by genetic features. Allelic expression of the polymorphic promoter region of the serotonin transporter (5-HTTLPR) was analysed as a relevant genetic factor for FM. Seventy-five patients meeting the American College of Rheumatology criteria and 27 healthy age-matched controls participated in this study. All controls and FM patients were submitted to genotyping of 5-HTTLPR. Twenty-seven FM patients, who were able to discontinue hypnotic, sedative or psychotropic prescription medications for at least 2 weeks, were then subdivided into L (homozygote LL) or S groups (genotypes LS and SS). They were evaluated for salivary cortisol levels, absolute number of leucocyte subpopulations, including natural killer (NK) cells and activated T and B lymphocytes. Both groups presented decreased cortisol levels, more intense in the L group, increased all B lymphocytes subsets and reduced CD4+CD25high T lymphocytes. The L group had increased CD4+CD25low activated T lymphocytes, while the S group displayed elevated CD4+ human leucocyte antigen D-related (HLA-DR)+ activated T lymphocytes and decreased NK cells. We demonstrate that genetic factors may help to identify FM individuals with differentially altered frequencies of immune cells.

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Chagas' disease is one of the few functional gastrointestinal disorders for which a causative agent has been identified. However, some pathological aspects of the chagasic megasyndromes are still incompletely understood. Chagasic megacolon is characterized by an inflammatory process, organ dilatation and neuronal reduction in both plexuses of the enteric nervous system (ENS). Although some studies on the ENS in Chagas' disease have been performed, the process of neuronal destruction and neuronal regeneration still remains unclear. Our hypothesis is that the regeneration process of the ENS may be involved with the mechanisms that prevent or retard organ dilatation and chagasic megacolon development. For that reason, we evaluated the neuronal regeneration with the marker GAP-43 in the colon's neuronal plexuses from chagasic patients with megacolon, and from non-infected individuals. Visual examination and quantitative analysis revealed an increased neuronal regeneration process in the dilated portion from chagasic patients when compared with the non-dilated portion and with non-infected individuals. We believe that this increased regeneration can be interpreted as an accentuated neuronal plasticity that may be a response of the ENS to avoid megacolon propagation to the entire organ and maintain the colon functional innervation.

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Neuronal destruction has been considered the hallmark of pathogenic mechanisms in chagasic megacolon. Characterization of neuropeptides in the enteric nervous system from chagasic patients with megacolon could elucidate some aspects of the development of this syndrome. In the present work we demonstrate the changes in expression of neuropeptides and neurochemical markers present in neuronal plexuses from the colons of chagasic patients with megacolon. Sections of frozen tissue samples were immunohistochemically labeled for anticalretinin, cChaT, substance P, VIP, NOS, and NPY. Immunoreactivity was observed using a confocal microscope. Our results demonstrate that in chagasic patients with megacolon, inhibitory motor neurons (VIP and NOS immunoreactive) are preferentially destroyed by Trypanosoma cruzi and/or the inflammatory process. These results suggest a selective destruction of enteric neurons in the colon of chagasic patients with megacolon, pointing to an important discovery in the mechanism of pathogenesis of Chagas' disease.

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The mechanisms involved in the pathogenesis of chagasic megacolon are not completely characterized. Although autoimmunity may play a role in the pathogenesis of Chagas' disease, recent studies suggest a positive association of tissue parasitism, inflammation, and severity of lesions. The aim of this study was to evaluate the role of inflammatory cells and the occurrence of fibrosis in the colon of chagasic patients with and without megacolon. Samples from 26 patients were randomly selected and paraffin-embedded tissue blocks were sectioned and evaluated by histology and immunohistochemistry to analyse the occurrence and relation among eosinophils, mast cells, macrophages and fibrosis. Section analyses showed that the presence of eosinophils and mast cells in the analysed inflammatory cells has a direct correlation with fibrosis density in the chagasic megacolon. These data suggest that the megacolon's pathogenesis is based on a continuous process of cell damage. Our data propose that eosinophils, mast cells and macrophages may have a direct connection with the occurrence of fibrosis in the colon of chagasic patients. We believe that potential therapeutic agents against these cells could avoid the fibrosis process and contribute to prevent the development of chagasic megacolon.

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Neuronal lesions have been considered the hallmark of chagasic megaesophagus, but the role of Trypanosoma cruzi and the participation of the inflammatory cells in this process are still debated. In the present study we counted neurons in the oesophagus from patients with and without megaesophagus and further examined these samples for the presence of parasite kDNA and cells with cytolytic potential (Natural Killer cells, cytotoxic lymphocytes and macrophages). The presence of parasite kDNA was demonstrated in 100% of cases with megaesophagus and in 60% of patients without megaesophagus. When analysed for the number of neurons, the patients without megaesophagus could be classified into 2 groups, as having normal or a decreased number of neurons. The former group did not show any inflammatory process, but interestingly, all patients without megaesophagus presenting decreased number of neurons also presented both parasite kDNA and inflammatory process in the organ. We further observed that the numbers of cytotoxic cells in the myenteric plexus region inversely correlate with the number of neurons. These data together strongly suggest that chronic lesions in chagasic megaesophagus might be a consequence of immune-mediated mechanisms, that last until the chronic phase of infection, and are dependent on the persistence of parasite in the host's tissue.

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We have previously shown that a low-stringency single-specific primer-polymerase chain reaction (LSSP- PCR) is a highly sensitive and reproducible technique for the genetic profiling of Trypanosoma cruzi parasites directly in tissues from infected animals and humans. By applying LSSP-PCR to the study of the variable region of kinetoplast minicircle from T. cruzi, the intraspecific polymorphism of the kinetoplast-deoxyribonucleic acid (kDNA) sequence can be translated into individual kDNA signatures. In the present article, we report on our success using the LSSP-PCR technique in profiling the T. cruzi parasites present in the hearts of 13 patients with chagasic cardiopathy and in the esophagi of four patients (three of them with chagasic megaesophagus). In two patients, one with the cardiodigestive clinical form of Chagas disease and the other with cardiopathy and an esophageal inflammatory process, we could study both heart and esophagus and we detected distinct kDNA signatures in the two organs. This provides evidence of a differential tissue distribution of genetically diverse T. cruzi populations in chronic Chagas disease, suggesting that the genetic variability of the parasite is one of the determining factors of the clinical form of the disease.

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