Macrophage migration inhibitory factor-2 of Wuchereria bancrofti suppressed the DSS-induced colitis in a mouse model by promoting alternative activation of peritoneal macrophages and increasing the number of Treg cells in the colon

Abstract

Abstract In this study, we cloned the homologue of macrophage migration inhibitory factor (MIF) secreted by the human filarial parasite Wuchereria bancrofti (rWbaMIF-2) and evaluated its potential in ameliorating inflammation in a dextran sulfate sodium salt (DSS)-induced colitis model. DSS administration resulted in substantial loss of body weight along with bloody diarrhea, severe inflammation in the colon and reduced length of the colon in just under 7 days. Treatment with rWbaMIF-2 reversed the clinical symptoms in DSS administered mice, characterized by no blood in the stools, minimal inflammation on the colon wall and the mice maintained normal colon length. rWbaMIF-2 treatment downregulated TNF-α, IL-6, IFN-γ, IL-1β, IL-17A, and NOS2 genes in the colon tissue and upregulated the percentage of IL-10 producing Treg and B1 cells in the colon and peritoneal cavity. Thus, one of the mechanisms by which rWbaMIF-2 induce its anti-inflammatory effect appeared to be by promoting the infiltration of IL-10 producing Treg cells into the colon. Further analysis showed alternative activation of F4/80+ large peritoneal macrophages (LPMs) with increased expression of arginase (p≤0.05) and reduced expression of iNOS, MPO activity, TNF-α, IL-6 and TLR4 in LPMs following rWbaMIF-2 treatment. Thus, for the first time, we demonstrate here that rWbaMIF-2 treatment can activate LMP macrophages alternatively and promote infiltration of Treg cells into the colon to suppress inflammation in a colitis model. These studies also demonstrate the potential of developing rWbaMIF-2 as a small molecule therapeutic agent for colitis and other inflammatory conditions. Studies funded by NIH RO1 AI116441.