Effects of heat stress on cytokine expression in broiler chicken infected with Salmonella Enteritidis

Abstract

This project request is intended to justify an exchange scholarship program of FAPESP. Indeed, it is part of the set goals for our doctoral project (Proc. FAPESP no 2009/52487-5). In this doctoral project, we seek to expand knowledge of Neuroimmunomodulation area in a poultry production context. In recent years, the influence of stress on the neuroimmune functions has been extensively studied on laboratory animals and humans research. Little attention has been given to the effects of stress on farm animals. In our previous work, we observed that heat stress (31 and 36 ° C) for 10h/dia for 6 days reduced weight gain and feed intake, it increased corticosterone serum levels and it decreased peritoneal macrophages activity in broilers. We also note the presence of enteritis characterized by increased presence of lymphocytes and plasmocytes within the lamina propria of the jejunum of heat stressed broiler chickens. We believe that the heat stress has produced alterations in the neuroimmune activity of the broiler chickens, consequently changing the HPA axis activityThese changes have influenced the production performance and the immunity, resulting in the onset of inflammatory bowel disease. In this sense, we develop a PhD project to evaluate the effects of heat stress (31 ± 1 ° C) on integrity and immunity of the intestinal mucosa, analyzing the relationship with a possible migration of Salmonella enteritidis to lymphoid tissues and liver. We emphasize that the current doctoral results showed that heat stress was able to decrease avian performance and increase corticosterone levels. Moreover, when we perform an experimental bacterial challenge, we also observed that stress impair performance parameters, increased migration of Salmonella enteritidis to spleen and decreased plasmatic IgA levels in broiler chickens. Although, we showed that heat stress induced enteritis in the small intestine of broilers and, decreased the plasmatic levels of IFN-³. Therefore, we proposes to study in The University of Guelph (Canada) the effects of heat stress on the expression of IL-1, IL-6, IL-10 and INF- ³, using real time PCR technique, in the spleen and cecal tonsils of broiler chickens infected with Salmonella enteritidis. (AU)