Heat-killed probiotic regulates the body's regulatory immunity to attenuate subsequent experimental autoimmune arthritis.
Immunol Lett. 2019 Oct 20. Epub 2019 Oct 20. PMID: 31644891
Administration of inactivated probiotics has been proved to enhance host immunity. Herein, we aim to explore their potential in modulating systemic autoimmune disorders. The bovine type II collagen (CII)-induced arthritis (CIA) and CII antibody-induced arthritis (CAIA) mice model was used in this study. Heat-killed Lactobacillus reuteri (h-L. reuteri) was administered before or after the induction of CIA. The results indicated that the severity of CIA was alleviated and the prevalence of CIA was decreased in the mice pre-treated with h-L. reuteri. Using enzyme-linked immunosorbent assays, we found that decreased serum CII-specific IgG antibody IL-6 and CXCL1 but the increased level of IL-10 was found in h-L. reuteri-treated cohort. Moreover, h-L. reuteri treatment decreased the severity and incidence of arthritis in the CAIA model which is associated with a early decrease of IL-6. Systematic supplement of exogenous IL-6 reversed h-L. reuteri-induced CIA suppression. For regulatory immune responses, the frequency of Tregs and CD4+IL-10+ cells was increased in the draining lymph of joint of h-L. reuteri-treated mice after second immunization. Parallelly, we found that if CIA was induced, CD103+ dendritic cells in mesenteric lymph nodes andα4β7+ Tregs in the spleen were increased in h-L. reuteri-treated mice, suggesting h-L. reuteri might affect the peripheral migration of Tregs to modulating CIA. Finally, the mice with progressive CIA were treated with h-L. reuteri after the second immunization. No alleviation of CIA severity, as well as an increase of splenic α4β7+ Tregs, was observed in these mice. This study indicates that pre-administration of h-L. reuteri can alleviate the CIA in mice and may serve as a promising strategy for autoimmune disease prevention.