Severity of murine arthritis induced by Freund's complete adjuvant is reduced by prior infection with the tapeworm parasite Hymenolepis diminuta

Abstract

Infection with helminth parasites can prevent or reduce the severity of colitis and airway inflammation in murine models of human inflammatory bowel disease and asthma. We postulated that infection with H. diminuta, which is spontaneously expelled from mice, would ameliorate the inflammation evoked by direct injection of Freund's complete adjuvant (FCA) into the knee joint, as a model of inflammatory joint disease. Male mice were orally gavaged with 5 viable H. diminuta cysticercoids in 100μl PBS and 8 days later received FCA (50 μl) into the right knee joint. Controls: a) PBS gavage + PBS knee injection, b) H. diminuta gavage + PBS injection, c) PBS gavage + FCA injection. Knee diameter was measured over a 7 day period and on sacrifice, blood samples were collected, spleen cells stimulated for cytokine production, knee joints extracted for myeloperoxidase (MPO) activity and RT‐PCR performed for cytokine mRNA expression. Mice infected with H. diminuta were significantly protected from FCA‐induced arthritis as shown by reduced knee swelling, fewer circulating neutrophils, lower MPO levels in the joint and reduced splenocyte TNFα production. Thus, our results show that prior infection with the helminth parasite, H. diminuta, significantly protects mice from the arthritic effects of FCA. Funded by CIHR.