Oat protein isolate-Pleurotus ostreatus -glucan conjugate nanoparticles bound to -carotene effectively alleviate immunosuppression by regulating gut microbiota

Individuals with immune disorders cannot establish an adequate defense to pathogens, leading to gut microbiota dysbiosis. beta-Carotene can regulate immune response, but its bioavailability in vivo is very low. Herein, we developed a glycosylated oat protein-based nanoparticle to improve the application of beta-carotene for mitigating cyclophosphamide-induced immunosuppression and gut microbiota imbalance in mice. The results showed that the nanoparticles facilitated a conversion of beta-carotene to retinol or retinyl palmitate into the systemic circulation, leading to an increased bioavailability of beta-carotene. The encapsulated beta-carotene bolstered humoral immunity by elevating immunoglobulin levels, augmenting splenic T lymphocyte subpopulations, and increasing splenic cytokine concentrations in immunosuppressed mice. This effect was accompanied by the alleviation of pathological features observed in the spleen. In addition, the encapsulated beta-carotene restored the abnormal gut microbiota associated with immunosuppression, including Erysipelotrichaceae, Akkermansia, Bifidobacterium and Roseburia. This study suggested that nanoparticles loaded with beta-carotene have great potential for therapeutic intervention in human immune disorders by specifically targeting the gut microbiota.