alpha 4 Integrins and sialyl Lewis x modulation in chronic Chagas disease: further evidence of persistent immune activation

The Unsolved Jigsaw Puzzle of the Immune Response in Chagas Disease

Trypanosoma cruzi interacts with the different arms of the innate and adaptive host's immune response in a very complex and flowery manner. The history of host-parasite co-evolution has provided this protozoan with means of resisting, escaping or subverting the mechanisms of immunity and establishing a chronic infection. Despite many decades of research on the subject, the infection remains incurable, and the factors that steer chronic Chagas disease from an asymptomatic state to clinical onset are still unclear. As the relationship between T. cruzi and the host immune system is intricate, so is the amount and diversity of scientific knowledge on the matter. Many of the mechanisms of immunity are fairly well understood, but unveiling the factors that lead each of these to success or failure, within the coordinated response as a whole, requires further research. The intention behind this Review is to compile the available information on the different aspects of the immune response, with an emphasis on those phenomena that have been studied and confirmed in the human host. For ease of comprehension, it has been subdivided in sections that cover the main humoral and cell-mediated components involved therein. However, we also intend to underline that these elements are not independent, but function intimately and concertedly. Here, we summarize years of investigation carried out to unravel the puzzling interplay between the host and the parasite.

Scrutinizing the Biomarkers for the Neglected Chagas Disease: How Remarkable!

Biomarkers or biosignature profiles have become accessible over time in population-based studies for Chagas disease. Thus, the identification of consistent and reliable indicators of the diagnosis and prognosis of patients with heart failure might facilitate the prioritization of therapeutic management to those with the highest chance of contracting this disease. The purpose of this paper is to review the recent state and the upcoming trends in biomarkers for human Chagas disease. As an emerging concept, we propose a classification of biomarkers based on plasmatic-, phenotype-, antigenic-, genetic-, and management-related candidates. The available data revisited here reveal the lessons learned thus far and the existing challenges that still lie ahead to enable biomarkers to be employed consistently in risk evaluation for this disease. There is a strong need for biomarker validation, particularly for biomarkers that are specific to the clinical forms of Chagas disease. The current failure to achieve the eradication of the transmission of this disease has produced determination to solve this validation issue. Finally, it would be strategic to develop a wide variety of biomarkers and to test them in both preclinical and clinical trials.

Chagas disease reactivation in HIV-coinfected patients: histopathological aspects

INTRODUCTION

Chagas disease reactivation has been described in severely immunocompromised patients by various etiologies, including in HIV-coinfected patients.

OBJECTIVE

This study aimed to perform histopathological and immunohistochemical evaluation of the brain, myocardium, esophagus and large bowel of autopsied patients with CHD and/or acquired immunodeficiency syndrome in comparison with control patients.

MATERIAL AND METHODS

Autopsy reports were reviewed from 1998 to 2012 and eight adult subjects were selected and divided into four groups: RE, CH, AI and CO. Sections of brain, myocardium, esophagus and large bowel were collected from each subject and processed for histological and immunohistochemical analysis. The histological sections stained with HE, Giemsa and picrosirius were used to quantify the density of inflammatory cells, the density of mast cells, and the percentage of collagen, respectively. Immunohistochemical analysis of IL17 and CD31 was performed.

RESULTS

The density of mast cells in the myocardium was significantly higher in the CH group than in the other groups. The density of mast cells in the esophagus and in the large bowel was significantly higher when compared to the other groups. The percentage of collagen in the esophagus, myocardium and large bowel was significantly lower in the RE group than in the CO group. The CH group had a higher percentage of collagen in the myocardium and in the large bowel in relation to the other groups. The density of cells immunostained with anti-IL17 was significantly higher in the large bowel and in the myocardium in the CH group than in the CO group. There was higher density of vessels immunostained with anti-CD31 in the myocardium and esophagus of the AI group than in the other groups. There were no significant correlations between the density of mast cells and percentage of collagen in the RE, CO, CH and AI groups.

CONCLUSION

Brain lesions observed in patients with CDR, as well as the higher density of cells immunostained with anti-IL17 at these sites, suggest that this cytokine was increasing local inflammation with subsequent tissue damage due to inflammation. Furthermore, the higher density of mast cells in the esophagus and large bowel of these subjects suggests that these cells might play a major role in esophageal and intestinal inflammation.

Differential expression of adhesion moleculesshaping the T-cell subset prevalence during the early phase of autoimmune and Trypanosoma cruzi-elicited myocarditis

The participation of cell adhesion molecules (CAMs) in the establishment of autoimmune and infectious myocarditis is an important matter of investigation and may have therapeutic implication. Trypanosoma cruzi infection induces a CD8-mediated myocarditis in patients with severe cardiomyopathy and experimental animals. Previously, we have proposed that this predominance of CD8+ T-cells is, at least in part, consequence of the differential expression of CAMs on circulating CD8+ lymphocytes. In the present study we investigated the participation of CAMs in shaping the phenotypic nature of the autoimmune CD4-mediated myosin-induced and the CD8-mediated T. cruzi-elicited myocarditis. We provide evidence that the prevalence of a certain T-cell subset inside the inflamed heart reflects the differential profile of the adhesion molecules VLA-4, LFA-1, and ICAM-1 displayed on a large proportion of this particular T-cell population in peripheral blood during the early phase of inflammation. Further, the expression of VCAM-1, ligand for VLA-4, and ICAM-1, counter-receptor for LFA-1, was up-regulated on vascular endothelium and paralleled the entrance of inflammatory cells into the cardiac tissue. Thus, this up-regulated expression of receptors-counter-receptors that regulate T-cell transmigration through the vascular endothelium may have an important role in the pathogenesis of the early phase of both autoimmune and infectious myocarditis.

Trypanosoma cruzi-elicited CD8+ T cell-mediated myocarditis: chemokine receptors and adhesion molecules as potential therapeutic targets to control chronic inflammation?

In Chagas disease, during the acute phase, the establishment of inflammatory processes is crucial for Trypanosoma cruzi control in target tissues and for the establishment of host/parasite equilibrium. However, in about 30% of the patients, inflammation becomes progressive, resulting in chronic disease, mainly characterized by myocarditis. Although several hypothesis have been raised to explain the pathogenesis of chagasic myocardiopathy, including the persistence of the parasite and/or participation of autoimmune processes, the molecular mechanisms underlying the establishment of the inflammatory process leading to parasitism control but also contributing to the maintenance of T. cruzi-elicited chronic myocarditis remain unsolved. Trying to shed light on these questions, we have for several years been working with murine models for Chagas disease that reproduce the acute self-resolving meningoencephalitis, the encephalitis resulting of reactivation described in immunodeficient individuals, and several aspects of the acute and chronic myocarditis. In the present review, our results are summarized and discussed under the light of the current literature. Furthermore, rational therapeutic intervention strategies based on integrin-mediated adhesion and chemokine receptor-driven recruitment of leukocytes are proposed to control T. cruzi-elicited unbalanced inflammation.