Abstract
Inflammatory response in Chagas disease is related to parasite and host factors. However, immune system regulation has not been fully elucidated. Thus, this study is aimed at evaluating IL-4 influence on acute phase of Trypanosoma cruzi experimental infection through dosage of cytokine levels in cardiac homogenate of infected Balb/c WT and Balb/c IL-4−/− as well as its histopathological repercussions. For such purpose, mice were divided into two groups: an infected group with 100 forms of the Colombian strain and an uninfected group. After 21 days of infection, animals were euthanized and the blood, spleen, and heart were collected. The spleen was used to culture splenic cells in 48 h. Subsequently, cytokines TNF-α, IL-12p70, IL-10, IFN-γ, and IL-17 were measured in the blood, culture supernatant, and heart apex by ELISA. The base of the heart was used for histopathological analysis. From these analysis, infected Balb/c IL-4−/− mice showed milder inflammatory infiltrate compared to Balb/c WT, but without changes in nest density and collagen deposition. IL-4 absence culminated in lower cardiac tissue IFN-γ production, although it did not affect TNF-α expression in situ. It also decreased TNF-α systemic production and increased IL-10, both systemically and in situ. In addition, IL-4 absence did not influence IL-17 expression. Splenocytes of IL-4-deficient mice produced higher amounts of IFN-γ, TNF-α, and IL-17 and lower amounts of IL-10. Thus, IL-4 absence in acute phase of experimental infection with T. cruzi Colombian strain reduces myocarditis due to lower IFN-γ production and greater IL-10 production in situ and this pattern is not influenced by splenocyte general repertoire.
Highlights
Chagas disease, known as American trypanosomiasis, is a chronic systemic infectious disease caused by the protozoanTrypanosoma cruzi (T. cruzi), an important public health problem in American continent
We demonstrate that in early stages of acute phase, IL-4−/− knockout animals presented milder myocarditis with lower IFN-γ production and higher in situ IL-10 production, despite Th1 cells increase in splenocyte general repertoire
Inflammatory cardiac infiltrate in Balb/c WT and Balb/c IL-4−/− mice infected with Colombian strain in acute phase of experimental Chagas disease was analyzed
Summary
Known as American trypanosomiasis, is a chronic systemic infectious disease caused by the protozoanTrypanosoma cruzi (T. cruzi), an important public health problem in American continent. Known as American trypanosomiasis, is a chronic systemic infectious disease caused by the protozoan. According to the World Health Organization (WHO), the disease affects around 7.5 million people worldwide, the majority in Latin America [1, 2]. Murine experimental model reproduces human Chagas’ disease infections, and genetic background has influences both, triggering a series of reactions that evolve from an acute symptomatic phase to chronic phase [3]. Balb/c strain mice are known to be susceptible to T. cruzi infection, present a high parasitemia and the vast majority succumb early to acute infection [4]. Prominent myocardial lesions with intense inflammatory process, evolution in parasitemia with peak between 21 and 25 days of postinfection, distinct myotropism with involvement of the skeletal musculature resulting in extensive lesions in the skeletal muscle fibers, electrocardiographic alterations, and resistance to chemotherapeutics such as benznidazole and nifurtimox are characteristics of this strain. Prominent myocardial lesions with intense inflammatory process, evolution in parasitemia with peak between 21 and 25 days of postinfection, distinct myotropism with involvement of the skeletal musculature resulting in extensive lesions in the skeletal muscle fibers, electrocardiographic alterations, and resistance to chemotherapeutics such as benznidazole and nifurtimox are characteristics of this strain. [6, 7]
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