The gut microbiota is essential for Trichinella spiralis-evoked suppression of colitis

Inflammatory bowel disease (IBD) increases the risk of colorectal cancer, and it has the potential to diminish the quality of life. Clinical and experimental evidence demonstrate protective aspects of parasitic helminth infection against IBD. However, studies on the inhibition of inflammation by helminth infection have overlooked a key determinant of health: the gut microbiota. Infection with helminths induces alterations in the host microbiota composition. However, the potential influence and mechanism of helminth infections induced changes in the gut microbiota on the development of IBD has not yet been elucidated. In this study, we analyzed the intersection of helminth Trichinella spiralis and gut bacteria in the regulation of colitis and related mechanisms. T. spiralis infected mice were treated with antibiotics or cohused with wild type mice, then challenged with DSS-colitis and disease severity, immune responses and goblet cells assessed. Gut bacteria composition was assessed by 16 s rRNA sequencing and SCFAs were measured. Results showed that protection against disease by infection with T. spiralis was abrogated by antibiotic treatment, and cohousing with T. spiralis- infected mice suppressed DSS-colitis in wild type mice. Bacterial community profiling revealed an increase in the abundance of the bacterial genus Muribaculum and unclassified_Muribaculaceae in mice with T. spiralis infection or mice cohoused with T. spiralis- infected mice. Metabolomic analysis demonstrated increased propionic acid in feces from T. spiralis- infected mice. Data also showed that the gut microbiome modulated by T. spiralis exhibited enhanced goblet cell differentiation and elevated IL-10 levels in mice. Taken together, these findings identify the gut microbiome as a critical component of the anti-colitic effect of T. spiralis and gives beneficial insights into the processes by which helminth alleviates colitis. Author SummaryInflammatory bowel disease (IBD) encompasses Crohns Disease and Ulcerative Colitis. It affects both children and adults. Reports have highlighted the potential use of helminths or their byproducts as a possible treatment for IBD. Accumulating evidence also suggests that the gut microbiota is a key factor in modulating IBD. In this study, we revealed the protective effect of a prior infection with T. spiralis on DSS-induced colitis in mice. Specifically, T. spiralis infection reshaped the gut microbiome of mice, resulting in an increased abundance of SCFA-producing bacteria Muribaculum and unclassified_Muribaculaceae and thereby producing a larger amount of propionic acid. Furthermore, the gut microbiome modulated by T. spiralis exhibited enhanced goblet cell differentiation and elevated IL-10 levels, ultimately ameliorating experimental colitis. These findings suggest that the modulation of host microbiota during T. spiralis infection plays a crucial role in the suppression of colitis, and any intention-to-treat with helminth therapy should be based on the patients immunological and microbiological response to the helminth.