Heligmosmoides polygyrus fourth stages induce protection against DSS‐induced colitis and change opioid expression in the intestine

Primary exposure of mice to the nematode Heligmosomoides polygyrus infection reduces inflammation in an experimental model of colitis. The aim of the present investigation was to evaluate whether the reduced inflammation provoked by H. polygyrus L4 larvae in BALB/c mice treated with dextran sulphate sodium is associated with changed expression of opioids in the small intestine and colon. Colitis was induced by 5% Dextran sulphate sodium (DSS) oral administration for 3 days before oral infection with 200 infective larvae (L3) H. polygyrus until the end of the experiment, 6 days post‐infection. Clinical disease symptoms were monitored daily. The expressions of proopiomelanocortin POMC1, MOR1 (Oprm1) – opioid receptor and β‐endorphin were determined by RT‐PCR, Western blot and immunoassay, respectively, in the colon and small intestine of mice. RT‐PCR analysis of colon tissues showed up‐regulation of the expression of POMC and MOR1 opioid‐dependent genes in mice with DSS‐induced colitis. H. polygyrus L4 larvae inhibited DSS‐induced colitis symptoms that were correlated with increased IL‐1β, TNF‐α, IL‐6, myeloperoxidase (MPO) concentration, macrophages infiltration and MOR1, POMC and β‐endorphin increased expression in the small intestine and inhibition of those in the colon.