Chlorella vulgaris Modulates Gut Microbiota and Induces Regulatory T Cells to Alleviate Colitis in Mice

Abstract

<i>Chlorella vulgaris</i> (<i>C. vulgaris</i>) is unicellular green algae consumed worldwide as a functional food. The immune stimulatory function of <i>C. vulgaris</i> is known; however, no study has elucidated its immune regulatory potential and associated microbiome modulation. In the current study, we aimed to validate the immune regulatory role of <i>C. vulgaris</i> mediated through two mechanisms. Initially, we assessed its ability to promote the expansion of the regulatory T cell (Treg) population. Subsequently, we investigated its impact on gut microbiota composition and associated metabolites. The supplementation of <i>C. vulgaris</i> altered the gut microbiota composition, accompanied by increased short-chain fatty acid (SCFAs) production in mice at homeostasis. We later used <i>C. vulgaris</i> in the treatment of a DSS-induced colitis model. <i>C. vulgaris</i> intervention alleviated the pathological symptom of colitis in mice, with a corresponding increase in Treg levels. As <i>C. vulgaris</i> is a safe and widely used food supplement, it can be a feasible strategy to instigate cross-talk between the host immune system and the intestinal flora for the effective management of inflammatory bowel disease (IBD).