Background: Alcoholic liver disease (ALD) pathogenesis is closely linked to gut microbiota dysbiosis and gut-liver axis imbalance. Interleukin-22 (IL-22) is a crucial cytokine for intestinal barrier integrity, and the polymeric immunoglobulin receptor (pIgR) plays key roles in mucosal immunity. This study aimed to investigate whether IL-22-engineered Lactobacillus ameliorates ALD by regulating the pIgR pathway.

Methods: An IL-22-engineered Lactobacillus reuteri strain was constructed using electroporation with pMG36e-Cat-IL-22 plasmid. ALD was induced in C57BL/6 mice and pIgR gene knockout mice using the Lieber-DeCarli alcohol diet for 6 weeks. Mice were divided into: normal control, ALD model, empty-vector L. reuteri (LR), and IL-22-engineered L. reuteri (LR-IL-22) groups (n=6/group). Liver function (ALT, AST), serum LPS, intestinal barrier integrity (tight junction proteins, histology), gut microbiota (16S rRNA sequencing), short-chain fatty acids (SCFAs, GC-MS), and hepatic macrophage polarization (flow cytometry) were assessed.

Results: LR-IL-22 intervention significantly reduced serum ALT, AST, and LPS levels in ALD mice compared to the model group (P<0.05). It restored intestinal tight junction protein expression (ZO-1, Occludin, Claudin-1), increased the villus height-to-crypt depth ratio, and ameliorated gut dysbiosis by increasing Bacteroidetes and beneficial genera (Bifidobacterium, Muribaculaceae) while reducing Firmicutes. Fecal SCFAs (propionic, butyric, acetic, valeric, isobutyric acids) were significantly elevated following LR-IL-22 treatment (P<0.05). LR-IL-22 also reduced the hepatic M1/M2 macrophage ratio and decreased pro-inflammatory cytokines  while increasing IL-10. In pIgR⁻/⁻ mice, ALD liver injury was exacerbated, and the therapeutic effects of LR-IL-22 were significantly attenuated, including failure to restore barrier function, correct dysbiosis, or normalize SCFA levels and macrophage polarization.

Conclusions: IL-22-engineered Lactobacillus ameliorates ALD by improving gut microbiota dysbiosis, enhancing intestinal barrier function, and reducing hepatic inflammation. These effects are mediated, at least in part, through the pIgR pathway. This engineered probiotic represents a promising therapeutic strategy for ALD.

An IL-22-engineered Lactobacillus reuteri strain was constructed using electroporation with pMG36e-Cat-IL-22 plasmid. ALD was induced in C57BL/6 mice and pIgR gene knockout mice using the Lieber-DeCarli alcohol diet for 6 weeks. Mice were divided into: normal control, ALD model, empty-vector L. reuteri (LR), and IL-22-engineered L. reuteri (LR-IL-22) groups (n=6/group). Liver function (ALT, AST), serum LPS, intestinal barrier integrity (tight junction proteins, histology), gut microbiota (16S rRNA sequencing), short-chain fatty acids (SCFAs, GC-MS), and hepatic macrophage polarization (flow cytometry) were assessed.

LR-IL-22 intervention significantly reduced serum ALT, AST, and LPS levels in ALD mice compared to the model group (P<0.05). It restored intestinal tight junction protein expression (ZO-1, Occludin, Claudin-1), increased the villus height-to-crypt depth ratio, and ameliorated gut dysbiosis by increasing Bacteroidetes and beneficial genera (Bifidobacterium, Muribaculaceae) while reducing Firmicutes. Fecal SCFAs (propionic, butyric, acetic, valeric, isobutyric acids) were significantly elevated following LR-IL-22 treatment (P<0.05). LR-IL-22 also reduced the hepatic M1/M2 macrophage ratio and decreased pro-inflammatory cytokines  while increasing IL-10. In pIgR⁻/⁻ mice, ALD liver injury was exacerbated, and the therapeutic effects of LR-IL-22 were significantly attenuated, including failure to restore barrier function, correct dysbiosis, or normalize SCFA levels and macrophage polarization.

IL-22-engineered Lactobacillus ameliorates ALD by improving gut microbiota dysbiosis, enhancing intestinal barrier function, and reducing hepatic inflammation. These effects are mediated, at least in part, through the pIgR pathway. This engineered probiotic represents a promising therapeutic strategy for ALD.