Accumulation of platelets in the liver may be an important contributory factor to liver injury in chronic hepatitis B virus infection

Background: Besides hemostatic properties, platelets have the features of inflammatory cells. Platelets have been shown to be contributed to the pathogenesis of acute liver damage of self-limited viral hepatitis and hepatitis B virus (HBV)-associated liver cancer in mouse models. However, the association between the platelets and chronic HBV infection remains largely unknown. We aimed to clarify whether an accumulation of platelets in the liver contributes to liver injury and fibrosis in chronic HBV infection. Methods: Sixty-five patients with chronic HBV infection who underwent liver biopsy were included. Twenty-three healthy liver tissue samples were obtained from donors whose livers were used for transplantation. The platelets in the liver tissues were identified by immunohistochemistry. According to the modified histology activity index described by Scheuer, the degree of hepatic inflammation and fibrosis of patients with chronic HBV infection was graded. Results: Patients with chronic HBV infection had a significantly more extensive CD61+ platelets in the liver tissues compared to healthy controls (69.08 +/- 6.21 vs. 16.68 +/- 2.05/HPF, P<0.001). Chronic HBV infected patients with higher inflammatory grading scores had more CD61+ platelets in their livers compared to those with lower scores (P<0.05). However, no association between liver platelets and fibrotic staging scores was found in the patients (r=0.069, P=0.586). The platelets in the liver tissues of patients with chronic HBV infection were also positively correlated with alanine transaminase (r=0.291, P=0.021), aspartate aminotransferase (r=0.328, P=0.009) and total bilirubin (r=0.236, P=0.036) levels. Conclusions: The accumulation of platelets in the liver may be involved in liver injury of patients with chronic HBV infection.