Stat3 activation-triggered transcriptional networks govern the early stage of HBV-induced hepatic inflammation

The chronic carrier state of the hepatitis B virus (HBV) often leads to the development of liver inflammation as carriers age. However, the exact mechanisms that trigger this hepatic inflammation remain poorly defined. We analyzed the sequential processes during the onset of liver inflammation based on time-course transcriptome and transcriptional regulatory networks in an HBV transgenic (HBV-Tg) mice model and chronic HBV-infected (CHB) patients (data from GSE83148). The key transcriptional factor (TF) responsible for hepatic inflammation occurrence was identified and then validated both in HBV-Tg mice and liver specimens from young CHB patients. By time-course analysis, an early stage of hepatic inflammation was demonstrated in 3-month-old HBV-Tg mice: a marked upregulation of genes related to inflammation (Saa1/2, S100a8/9/11, or Il1β), innate immunity (Tlr2, Tlr7, or Tlr8), and cells chemotaxis (Ccr2, Cxcl1, Cxcl13, or Cxcl14). Within CHB samples, a unique early stage of inflammation activation was discriminated from immune tolerance and immune activation groups based on distinct gene expression patterns. Enhanced activation of TF Stat3 was strongly associated with increased inflammatory gene expression in this early stage of inflammation. Expression of phosphorylated Stat3 was higher in liver specimens from young CHB patients with relatively higher alanine aminotransferase levels. Specific inhibition of Stat3 activation significantly attenuated the degree of liver inflammation, the expression of inflammation-related genes, and the inflammatory monocytes and macrophages in 3-month-old HBV-Tg mice. Stat3 activation is essential for hepatic inflammation occurrence and is a novel indicator of early-stage immune activation in chronic HBV carriers. Until now, it remains a mystery that chronic hepatitis B virus (HBV)-infected patients in the "immune tolerance phase" will transition to the "immune activation phase" as they age. In this study, we reveal that Stat3 activation-triggered hepatic transcriptional alterations are distinctive characteristics of the early stage of immune/inflammation activation in chronic HBV infection. For the first time, we discover a mechanism that might trigger the transition from immune tolerance to immune activation in chronic HBV carriers.