Capsular Polysaccharide of <i>Lactiplantibacillus plantarum</i> DPUL F232 Alleviates Whey Protein Allergy by Regulating Immunity, Gut Microbiota, and Production of SCFAs

Probiotics have been proven to relieve cow milk allergy (CMA), but their key bacterial components are still unclear. Capsular polysaccharide (CPS) is an important component of the cell wall of lactic acid bacteria, which has the potential for immunomodulation and allergy relief. In this study, we isolated the CPS of <i>Lactiplantibacillus plantarum</i> DPUL F232 and analyzed its alleviating effect on whey protein allergy. The results showed that <i>Lpb. plantarum</i> DPUL F232 CPS could significantly reduce IgE, histamine, and mast cell protease, regulate cellular immunity, and was accompanied by changes in immune and inflammatory signaling pathways. In addition, CPS significantly regulated the gut microbiota, and the total short-chain fatty acids (SCFAs) were increased by 1.5 times. In summary, <i>Lpb. plantarum</i> DPUL F232 CPS can regulate whey protein allergy by multiple pathways. The present study provides a research basis for the potential antiallergic activity of CPS and its application in functional foods.