Effect of HM-22 on immunoregulation and intestinal microbiota in α-lactalbumin-induced allergic mice.

Milk protein is one of the eight major allergens, and α-lactalbumin (α-LA) is one of the major allergens of bovine milk protein. Our previous studies found that HM-22 ( HM-22) showed a good gastrointestinal survival rate and intestinal colonization. To investigate the effect of HM-22 on intestinal inflammation and intestinal microbiota in α-LA-induced allergic mice, in this study, HM-22 at low and high doses was intragastrically administered to α-LA-induced allergic mice for 5 weeks. The results showed that HM-22 significantly relieved the weight loss and organ index of α-LA-induced allergic mice ( < 0.05). HM-22 increased the levels of interleukin-10 (IL-10), interferon-γ (IFN-γ) and transforming growth factor-β (TGF-β) in the serum of α-LA-induced allergic mice and decreased the levels of total immunoglobulin E (IgE) and the proinflammatory factor interleukin-4 (IL-4) ( < 0.05). The crypt structure of the colon tissues of α-LA-induced allergic mice changed, goblet cells decreased, and the phenomenon of a large number of inflammatory corpuscles that appeared was improved and alleviated with the intervention of HM-22 by hematoxylin-eosin (HE) staining. Western blot analysis showed that HM-22 significantly increased the expression of occludin and claudin-1 in the colon of α-LA-induced allergic mice and decreased the expression of the inflammatory proteins p65 and IκBα ( < 0.05). The intestinal microbiota of mice in each group was determined by 16S rRNA amplicon sequencing, and the results showed that intervention with HM-22 improved the intestinal microbes of α-LA-induced allergic mice. Spearman's correlation analysis revealed the correlation between intestinal microbiota changes and the α-LA-induced allergy-related index. This study provides a theoretical basis for probiotics to prevent allergies by changing the intestinal microbiota.