Endomyocardial fibrosis pathogenesis: Immunological profile and proteomics analysis of cardiac tissue

INTRODUCTION: Endomyocardial fibrosis (EMF) is a typical disease in tropical countries, characterized by the fibrous deposition in the endomyocardium, with severe clinical manifestations. EMF pathogenesis is still unclear, but one of the major hypothesis suggests that EMF could be a consequence of a chronic inflammatory process with possible involvement of a Th2 immune responses after helminthiasis, mediated by eosinophils, which could contribute to pathogenesis in the early stages of the disease. In this study, we evaluated the inflammatory response profile and the protein expression profile of the affected endomyocardium, to understand the mechanisms involved in this pathogenesis. METHODS: Plasma and serum samples were collected from the 27 patients diagnosed with advanced stage EMFand from healthy controls, to mensured plasma levels of 6 cytokines belonging to the Th1/Th2 cytokine profiles, ultrasensitive C Reactive Protein (CRP), total and allergen-specific serum IgE against prevalent and helminthic allergens. Proteomic analysis of tissue samples obtained from 4 EMF patients submitted to surgical resection of affected endomyocardial tissue allowed the identification of proteins by mass spectrometry, after separation by 1D and 2D electroforesis. In silico analysis of functional pathways and networks connecting the proteins identified in the EMF cardiac tissue was also performed. Blood peripheral eosinophilia, clinical and echocardiography data were evaluated retrospectively. RESULTS: All EMF patients displayed detectable plasma levels of at least one of the cytokines tested. We found that TNF-?, IL-6, IL-4 and IL-10 were each detected in at least 74% of tested sera, and plasma levels of IL10, IL6 and TNF-? were significantly higher than controls. Plasma levels of such cytokines positively correlated with each other. Only 33% of the patients presented any episode of blood eosinophilia along time, and 11% of these patients presented hypereosinophilia. Total IgE levels were similar to those from healthy subjects. Proteomic analysis allowed the identification of 140 distinct proteins from the resected endomiocardium of the EMF patients, 18 of which belonging to the extracellular matrix. In silico analysis indicated IL-6 and TNF-? as two of the major gene expression inducers of the identified proteins in our analysis, and the Acute Phase Response was identified as the major canonical pathway involved with the identified set of proteins. Similarly, CRP levels were significantly increased in the EMF patients. CONCLUSIONS: Increased levels of an inflammatory/anti-inflammatory circulating cytokines (Th1/Th2), along with increased CRP levels, suggested the presence of a mixed inflammatory profile in EMF advanced stage. The number of EMF patients with blood eosinophilia does not support the active participation of eosinophils in pathogenesis of advanced EMF. However, it is not possible to exclude the participation in the pathogenesis early stages. Our data support the hypothesis that the increased levels of inflammatory cytokines modulate protein expression -including proteins of the acute phase response - in the endomyocardial tissue of EMF patients (AU)