Gut commensal bacterium Bacteroides vulgatus exacerbates helminth-induced cardiac fibrosis through succinate accumulation.

Trichinella spiralis (Ts) is known to cause cardiac fibrosis, which is a critical precursor to various heart diseases, and its progression is influenced by metabolic changes. However, the metabolic mechanisms remain unclear. Here, we observed that Ts-infected mice exhibited cardiac fibrosis along with elevated succinate levels in the heart using metabolomic analysis. Administration of succinate exacerbated fibrosis during Ts infection, while deficiency in succinate receptor 1 (Sucnr1) alleviated the condition, highlighting the role of the succinate-Sucnr1 axis in fibrosis development. Furthermore, metagenomics sequencing showed that Ts-infected mice had a higher abundance ratio of succinate-producing bacteria to succinate-consuming bacteria in the intestines. Notably, the succinate-producer Bacteroides vulgatus was enriched in Ts group. Oral supplementation with B. vulgatus aggravated Ts-induced cardiac fibrosis. In summary, our findings underscore the succinate-Sucnr1 axis as a critical pathway in helminth-induced cardiac fibrosis and highlight the potential of targeting this axis for therapeutic interventions. This study presents novel insights into the gut-heart axis, revealing innovative strategies for managing cardiovascular complications associated with helminth infections.