Estudo das populações de linfócitos T, NK e NKT na lâmina própria no pico da inflamação da mucosite intestinal induzida por 5-fluorouracil em camundongos C57BL6/J

Abstract

Cancer is a disease that originates through genomic alterations that occur by defects in the systematic process of cell injury and repair. 5-fluorouracil (5-FU) is one of the most used anti-neoplastic drugs in the cancer treatment, exerting multiple effects on abnormal cell growth. 5-FU treatment affects rapidly proliferating tissues, causing mucositis, anorexia, nausea, vomiting and diarrhea. Natural Killer (NK) cells of the innate immunity, T cells of the acquired immunity, and Natural Killer T cells (NKT), which can play immunomodulatory activities, are present mainly in the intestinal mucosa. The aim of this study was to identify and characterize the populations of NK, T lymphocytes, and NKT cells in the lamina propria of C57BL6J mice challenged by 5-FU-induced intestinal mucositis. We have used male mice weighing 19 to 25g, challenged by intraperitoneal injection of 5FU (n=6) or saline (n=6) (150mg/kg, single dose) and euthanized after 72h. The small intestine segments were harvested for histological processing and morphometric analyses and for the myeloperoxidase activity assay. The extraction of the lamina propria lymphocytes from the overall small intestine was also conducted for flow cytometry analyses. Blood was drawn from the retroorbital plexus for leucocyte counting. Mice were weighed daily prior to 5-FU administration until the day of euthanasia. The 5-FU challenge (150 mg/kg, single dose, i.p.) led to weight loss, reduction of leucocyte counts at the time of villi and reason villus/crypt and increased crypt depth in all small intestinal segments. The flow cytometry data have shown that 5-FU-treated group had a reduction in the frequency of NK cells (CD16+) and CD3+ CD4+ cells. In the same group, an increased frequency of NKT cells (CD16+) and CD3+ CD8+ cells was found. Altogether our findings suggest that 5-FU-induced intestinal mucositis affects the frequency of different T and NK cells populations in the lamina propria. More in-depth studies are warranted to unfold the mechanisms that led to these changes, taking into account the immunoinflammatory effects of 5-FU.