Objective:To investigate the impacts of 1,25-dihydroxyvitamin D 3 (VD) and Lactobacillus plantarum (LP) on intestinal flora in animals with metabolic dysfunction-associated fatty liver disease (MAFLD) and their possible mechanisms. Methods:A methionine- choline-deficient (MCD) diet-induced rat model of MAFLD was created. Forty 10-week-old male Sprague-Dawley rats were randomized into methionine-choline-sufficient (MCS) group, MCD group, VD group, LP group, and VD-LP group, with 8 rats in each group. The intervention groups (VD group, LP group, and VD-LP group) were gastrically fed with VD peanut oil solution (6 ng/100 g daily), Lactobacillus plantarum solution (2×10 9CFU/100 g daily), and a combination of these two solutions, respectively. MCS group, MCD group, and LP group were given the same volume of peanut oil on a daily basis. Fecal samples from rats were collected at week 4 and analyzed using 16S rRNA gene sequencing for fecal flora structure. Portal vein blood samples were collected to detect liver biochemistry and lipopolysaccharide (LPS) levels. Pathological changes in liver and terminal ileum tissues were observed using hematoxylin and eosin (H&E) staining. Results:Compared with the MCS group, the MCD group exhibited massive steatosis and lipid infiltration in liver tissues, markedly thinned ileum mucosa, severely damaged villi structure, excessive necrotic and shedding of epithelial cells, and infiltration of inflammatory cells. Compared with the histopathological changes in the MCD group, the steatosis and lipid infiltration of liver tissue, the damage to the ileal mucosa structure and epithelial cells, and the infiltration of inflammatory cells were alleviated in the VD group, LP group, and VD-LP group. Compared with MCS group, the MCD group had significantly higher serum alanine aminotransferase (ALT) (158.50±14.03 U/L vs. 20.38±7.39 U/L), aspartate aminotransferase (AST) (43.88±11.36 U/L vs. 25.75±5.90 U/L), total bile acid (TBA) (140.60±11.77 μmol/L vs. 19.96±4.31 μmol/L), and LPS (16.57±1.19 pg/ml vs. 7.43±0.95 pg/ml) (All P<0.001),which confirmed the successful establishment of rat models of MAFLD. Serum ALT, AST, TBA, and LPS levels in all the three intervention groups were significantly lower than those in MCD group, and the most significant reductions in ALT (51.38±9.05 U/L vs. 158.50±14.03 U/L), AST (55.88±12.19 U/L vs. 143.88±11.36 U/L), TBA (21.00±8.17 μmol/L vs. 140.60±11.77 μmol/L), and LPS (9.72±0.71 pg/ml vs. 16.57±1.19 pg/ml) were seen in the VD-LP group. The microbiota in the MCD group predominantly featured Muribaculaceae, while the MCS group and other intervention groups primarily harbored Lactobacillus. Firmicutes and Lactobacillus were significantly decreased in the MCD group ,while Bacteroidete, Proteobacteria, Verrucomicrobiota, Prevotellaceae UCG-003, Escherichia coli, Bacteroides, and Enterococcus increased significantly. The opposite was true for each intervention group. There were significant differences in Lactobacillus between MCD group and the other four groups. Conclusion:VD and LP can remarkably improve lipid deposition in MAFLD by regulating intestinal flora.

Objective:To investigate the impacts of 1,25-dihydroxyvitamin D 3 (VD) and Lactobacillus plantarum (LP) on intestinal flora in animals with metabolic dysfunction-associated fatty liver disease (MAFLD) and their possible mechanisms. Methods:A methionine- choline-deficient (MCD) diet-induced rat model of MAFLD was created. Forty 10-week-old male Sprague-Dawley rats were randomized into methionine-choline-sufficient (MCS) group, MCD group, VD group, LP group, and VD-LP group, with 8 rats in each group. The intervention groups (VD group, LP group, and VD-LP group) were gastrically fed with VD peanut oil solution (6 ng/100 g daily), Lactobacillus plantarum solution (2×10 9CFU/100 g daily), and a combination of these two solutions, respectively. MCS group, MCD group, and LP group were given the same volume of peanut oil on a daily basis. Fecal samples from rats were collected at week 4 and analyzed using 16S rRNA gene sequencing for fecal flora structure. Portal vein blood samples were collected to detect liver biochemistry and lipopolysaccharide (LPS) levels. Pathological changes in liver and terminal ileum tissues were observed using hematoxylin and eosin (H&E) staining. Results:Compared with the MCS group, the MCD group exhibited massive steatosis and lipid infiltration in liver tissues, markedly thinned ileum mucosa, severely damaged villi structure, excessive necrotic and shedding of epithelial cells, and infiltration of inflammatory cells. Compared with the histopathological changes in the MCD group, the steatosis and lipid infiltration of liver tissue, the damage to the ileal mucosa structure and epithelial cells, and the infiltration of inflammatory cells were alleviated in the VD group, LP group, and VD-LP group. Compared with MCS group, the MCD group had significantly higher serum alanine aminotransferase (ALT) (158.50±14.03 U/L vs. 20.38±7.39 U/L), aspartate aminotransferase (AST) (43.88±11.36 U/L vs. 25.75±5.90 U/L), total bile acid (TBA) (140.60±11.77 μmol/L vs. 19.96±4.31 μmol/L), and LPS (16.57±1.19 pg/ml vs. 7.43±0.95 pg/ml) (All P<0.001),which confirmed the successful establishment of rat models of MAFLD. Serum ALT, AST, TBA, and LPS levels in all the three intervention groups were significantly lower than those in MCD group, and the most significant reductions in ALT (51.38±9.05 U/L vs. 158.50±14.03 U/L), AST (55.88±12.19 U/L vs. 143.88±11.36 U/L), TBA (21.00±8.17 μmol/L vs. 140.60±11.77 μmol/L), and LPS (9.72±0.71 pg/ml vs. 16.57±1.19 pg/ml) were seen in the VD-LP group. The microbiota in the MCD group predominantly featured Muribaculaceae, while the MCS group and other intervention groups primarily harbored Lactobacillus. Firmicutes and Lactobacillus were significantly decreased in the MCD group ,while Bacteroidete, Proteobacteria, Verrucomicrobiota, Prevotellaceae UCG-003, Escherichia coli, Bacteroides, and Enterococcus increased significantly. The opposite was true for each intervention group. There were significant differences in Lactobacillus between MCD group and the other four groups. Conclusion:VD and LP can remarkably improve lipid deposition in MAFLD by regulating intestinal flora.