The effect of Lactococcus lactis D4 on the expression of Ki-67 and liver fibrosis in a rat model of obstructive jaundice.

Backgrounds/aims: Obstructive jaundice, resulting from bile duct obstruction, is associated with increased morbidity and mortality due to impaired bile flow, dysbiosis of the gut microbiota, enhanced bacterial translocation, and hepatocellular injury. Persistent biliary obstruction can further progress to hepatic fibrosis and ultimately cirrhosis. Probiotics might help modulate microbiota and reduce liver injury. This study investigates the effect of Lactococcus lactis D4 on Ki-67 expression and liver fibrosis in rats with obstructive jaundice.

Methods: Fifteen male Wistar rats (10-16 weeks old) were divided into three groups: sham (laparotomy only), BDL (bile duct ligation without treatment), and BDL-LLD4 (BDL followed by L. lactis D4). After 7 days, liver wedge biopsies were taken for Ki-67 immunohistochemical staining and assessment of fibrosis using the METAVIR score.

Results: The highest mean Ki-67 expression was observed in the BDL-LLD4 group (14.20 ± 3.35), significantly higher than in the sham (7.60 ± 2.61; p < 0.05) and BDL groups (3.40 ± 1.34; p < 0.01). The Metavir fibrosis score was lower in the BDL-LLD4 group, but not significantly, suggesting reduced liver damage.

Conclusions: Administration of L. lactis D4 in an obstructive jaundice model resulted in a significant upregulation of Ki-67 expression and attenuation of liver fibrosis compared to the BDL group. These results suggest that L. lactis D4 exhibits hepatoprotective effects by promoting liver regeneration and suppressing fibrogenesis, thereby supporting its potential as an adjunctive probiotic therapy for liver disease and preventing postoperative liver failure.