Lactiplantibacillus plantarum YY-112 ameliorates mouse immunosuppression by enhancing B/T-cell activation and maintaining Th1/Th2 homeostasis

In recent years, the development of immunosuppression has become common, and probiotics are a vital immunomodulatory strategy. This study evaluated the alleviating effect of Lactiplantibacillus plantarum (L. plantarum) YY-112 on cyclophosphamide-induced immune imbalance and resolved the possible mechanism of action. L. plantarum YY-112 at 10⁹ CFU/mL lowered loss of body weight and alleviated splenic injury, intestinal injury, and inflammation, according to the hematoxylin and eosin staining. Biochemical results showed that 10⁹ CFU/mL L. plantarum YY-112 increased interleukin-10 and immunoglobulin M levels and decreased interferon-γ levels. Additionally, the immunoregulatory effect at the molecular levels of L. plantarum YY-112 was analyzed by transcriptome sequencing. L. plantarum YY-112 significantly upregulated Cr2 and downregulated C5aR1 to regulate the complement system; downregulated S100a8, S100a9, and Mmp9 to inhibit neutrophil aggregation; upregulated Cd19, Cd72, Cd3e, Cd28, Cd80, Cd8a, and histocompatibility-2-related genes to regulate B- and T-cell activation; and upregulated Xiap, Malt1, Ikbkb, Mapk11, Mef2c, Mapk12, Ras, and Myc to activate immune signaling pathways. Furthermore, L. plantarum YY-112 improved intestinal microbial structure and reduced enrichment of Lachnospiraceae_NK4A136_group, norank_f_Lachnospiraceae, Desulfovibrio, Colidextribacter, and Helicobacter. In conclusion, these findings offer valuable insights into the potential mechanisms through which L. plantarum YY-112 regulates immune imbalance.