Participação de citocinas pró-inflamatórias e quimiocinas no recrutamento e ativação celular no granuloma hépatico e possíveis associações destes mediadores imunológicos com a morbidade da esquistossomose em área endêmica e em modelo murino

Abstract

The formation and modulation of hepatic granuloma in response to retention of Schistosoma mansoni eggs retained in the tissues is an inflammtory immune-mediated process of fundamental importance for the evolution of morbidity. In this study we evaluate the involvement of pro-inflammatory chemokines and cytokines in human schistosomiasis and morbidity in the cells recruitment and activation in hepatic granuloma in experimentally infected mice. Plasma samples 97 patients infected with S. mansoni, with diagnosis by stool examination by Kato-Katz method and the morbidity determined by clinical and sonographic evaluations. The concentration of the soluble TNF-α receptor (sTNF-R1), MIF and chemokines CCL3, CCL24 and CCL7 were determined by ELISA. Multivariate linear regression models were used to analyze the relationship between the concentration of quiomicinas and cytokines and co-morbidity variables investigated. Data showed that the study population had low parasite burden, with a median of 36 eggs per gram of feces, which was not different between genders, age or in patients who reported previous anthelmintic treatment. MIF levels, CCL3, CCL7 and CCL24 in plasma were not associated with parasite load, but the levels of sTNF-R1 were positively associated with the parasite load. Higher plasma concentrations of MIF and sTNF-R1 and chemokines CCL3 and CCL24 were positively associated with liver fibrosis parameters, such as increasing the thickness of the portal vein and gallbladder. Plasma levels quantified CCL7 showed no relationship to morbidity parameters. The data indicate that elevated levels of proinflammatory cytokines and type-2 chemokine response may indicate the severity of chronic human schistosomiasis. To better understand the recruitment and activation of cells for hepatic granulomas mice genetically deficient in the production of CCL3 and CCR5 receptor and nondeficient were infected subcutaneously (25 cercariae/animal) and comparatively evaluated for parasitic burden, morbidity parameters and the composition and activity of hepatic granuloma isolated cells. There wasn´t differences in the number of worms recovered from the circulation, the number of eggs deposited in the liver and eliminated in the feces of the animals of the different experimental groups. Despite the similar parasite burden, the animals deficient in CCR5 receptor had severe schistosomiasis, an increase of liver and spleen, increased collagen deposition in the granuloma and increased production of serum transaminases, while mice deficient in CCL3 have milder disease in relation to wildlife. In these mice, granulomas was reduced cellularity and reduced production of cytokines and chemokines from different profiles. In the liver granulomas isolated from CCR5-/- mice chronically infected was found higher concentration of pro-inflammatory cytokines and Th2 profile in CCL3-/- animals, and this increase is associated with increased recovery CD4 lymphocytes activated and lower recovery of Treg lymphocytes . Furthermore, the absence of CCR5 influences the M2 macrophage activation leading to a decrease in ARG1 activity and TGF-β production. These results suggest the involvement of chemokines and pro-inflammatory cytokines in the development of severe forms of schistosomiasis.