Estudos de mecanismos imunopatobiológicos da mucosite experimental

Abstract

The pathophysiology of mucositis, a common complication in chemotherapy treatment for cancer, is poorly understood. The aim of this study was to elucidate immunological mechanisms associated with mucositis. We use a model of doxorubicin-induced mucositis i.p. (Doxo, 10 mg / kg and we performed weight curve and immunological, histopathological and intestinal permeability assessments (DTPA-99mTc), at 6 and 24 hours, 3, 5 and 7 days after mucositis induction (ddm). mucositis, BALB/c mice presented, between 1 and 3 ddm, weight loss, increased intestinal permeability, shortening of intestinal villi with decreased crypt depth, and areas of ulceration at histopathology. epithelial cells (apoptosis), stem cells (apoptosis and necrosis) and lymphocytes (apoptosis) with reactive proliferation in all these strains.Three days later we observed an inflammatory infiltrate with strong Th2, ILC2, neutrophil and eosinophil cells. RNA expression for cell damage-associated cytokines such as TSLP and IL25 involved in Th2 and ILC2 cell activation increase 6 hours after mucositis induction and show variations over the days. On the other hand, proinflammatory cytokines of type 2 profile decreased (IL4 and IL9) or increased (IL5) in the first 3 days of injury when compared to the SHAM group (injected with PBS). Tissue regeneration- associated cytokines (IL22) showed increased expression in the first hours followed by inhibition on day 3, movement accompanied by amphiregulin that was also found inhibited on day 3. Like most other parameters, cytokine expression returned to normal within the first few hours. day 7 after mucositis induction. To verify the relevance of the type 2 immune response in mucositis, we induced mucositis in ST2-deficient mice (IL33 receptor, another important cytokine for ILC2 and Th2 differentiation, but which did not show differential expression during mucositis compared to the control group). ). Although these animals present melena, we observed only a small, non-statistically significant delay in the recovery of intestinal architecture at 7 ddm, as well as a non-significant delay in the resolution of intestinal permeability increase and weight evolution similar to the group of wild controls, suggesting a significant role. IL33 in the recovery and intestinal integrity. Eosinophil-deficient mice (ΔdblGATA-1), on the other hand, did not show weight loss when compared to their wild control with mucositis, suggesting an important participation of these cells in the deleterious effects of mucositis. As neutrophils also increased during mucositis, we performed neutrophil depletion (using antibody 1A8) or inhibited their migration (using DF 2162) and observed that there was 9 no change in weight evolution, permeability or histopathology, suggesting secondary involvement of this cell in pathophysiology of mucositis. On the other hand, T and B cell deficient mice (RAG1 KO) have the same mucositis profile as wild type (WT) mice, suggesting that the adaptive immune system plays no important role in this model. In contrast, mice deficient in T, B, NK and ILC cells (NSG KO) showed high susceptibility to the doxorubicin mucositis model, with 100% mortality. When we performed the adoptive transfer of ILC2 to NSG KO mice we observed restoration of survival and clinical parameters like WT mice. Our data suggest that the innate ILC2-mediated immune response promotes recovery of the injured bowel during the mucositis process while eosinophils promote associated pathology.