HBV infection suppresses the expression of inflammatory macrophage miR­210.

It has been previously reported that hepatitis B e­antigen (HBeAg) induces microRNA (miR)­155 expression and promotes liver injury by increasing inflammatory cytokine production in macrophages. Moreover, it was previously demonstrated that miR­210 alleviates lipopolysaccharide­stimulated proinflammatory cytokine production in macrophages. In addition, accumulating evidence suggests that miR­210 is able to suppress hepatitis B virus (HBV) replication in HepG2.2.15 cells. However, it remains unclear whether miR­210, similar to miR­155, affects the progress of hepatitis B by regulating macrophage function. Reverse transcription­quantitative polymerase chain reaction analysis was used to detect miR­210 levels in serum and cells. HBV­associated antigens stimulated different types of macrophages and facilitated the observation of the effects of these antigens on miR­210 expression in macrophages. Co­culture of peripheral blood monocytes from healthy controls and the serum of patients with chronic hepatitis B (CHB) was conducted to evaluate the effect of HBV­associated elements in the serum on the expression of the macrophage miR­210 in vivo. It was observed that miR­210 expression levels were decreased in the peripheral blood monocytes (PBMs) and serum of patients with CHB and negatively associated with serum alanine aminotransferase and aspartate aminotransferase, but not other clinical parameters including hepatitis B surface antigen (HBsAg), HBeAg, anti­HBe antibody (HBeAb) and hepatitis B core antibody (HBcAb) and HBV­DNA. Notably, it was demonstrated that miR­210 expression was not affected by treatment with HBV­associated antigens in different types of macrophages. Notably, the serum of patients with CHB was able to markedly downregulate the miR­210 expression of PBMs in healthy controls. These findings suggested that, unlike the induction of miR­155 by HBeAg, there may be certain other elements, apart from HBV­associated antigens, regulating miR­210 levels in the serum and PBMs of patients with CHB that affect macrophage activation.

The E3 ubiquitin ligase MuRF2 attenuates LPS-induced macrophage activation by inhibiting production of inflammatory cytokines and migration.

Muscle RING-finger (MuRF) proteins are E3 ubiquitin ligases that are expressed in striated muscle. MuRF2 is an important member of this family, but whether it is expressed in tissues other than striated muscle has not been thoroughly elucidated to date. In this study, we determined that MuRF2 is also expressed in other vital organs, including liver, lung, brain, spleen and kidney. Moreover, we show that the level of MuRF2 expression is significantly decreased in hepatic mononuclear cells of mice with lipopolysaccharide (LPS)/d-galactosamine-induced hepatitis and negatively correlated with the serum levels of alanine aminotransferase and aspartate aminotransferase in these mice. Furthermore, the expression of MuRF2 was down-regulated in RAW264.7 cells activated with LPS but not in cells treated with polyinosinic-polycytidylic acid (Poly(I:C)) or with lipidosome plus Poly(I:C). We also found that MuRF2 was able to translocate from the cytoplasm to the nucleus in RAW264.7 cells activated with LPS but not in cells treated with Poly(I:C). In addition, we demonstrated that interleukin 6 and tumour necrosis factor α production and macrophage migration were inhibited after MuRF2 was overexpressed in RAW264.7 cells. We further verified that nuclear factor-κB p65 subunit level was greatly reduced in RAW264.7 macrophage nuclei by gain of function. Taken together, these findings indicate that MuRF2 may rescue LPS-induced macrophage activation by suppressing the production of proinflammatory cytokines and cell migration. We also identify a novel function of MuRF2 in non-muscle tissues and cells.

HBeAg induces the expression of macrophage miR-155 to accelerate liver injury via promoting production of inflammatory cytokines.

Activation of Kupffer cells (KCs) induced that inflammatory cytokine production plays a central role in the pathogenesis of HBV infection. The previous studies from our and other laboratory demonstrated miRNAs can regulate TLR-inducing inflammatory responses to macrophage. However, the involvement of miRNAs in HBV-associated antigen-induced macrophage activation is still not thoroughly understood. Here, we evaluated the effects and mechanisms of miR-155 in HBV-associated antigen-induced macrophage activation. First, co-culture assay of HepG2 or HepG2.2.15 cells and RAW264.7 macrophages showed that HepG2.2.15 cells could significantly promote macrophages to produce inflammatory cytokines. Furthermore, we, respectively, stimulated RAW264.7 macrophages, mouse primary peritoneal macrophages, or healthy human peripheral blood monocytes with HBV-associated antigens, including HBcAg, HBeAg, and HBsAg, and found that only HBeAg could steadily enhance the production of inflammatory cytokines in these cells. Subsequently, miRNAs sequencing presented the up- or down-regulated expression of multiple miRNAs in HBeAg-stimulated RAW264.7 cells. In addition, we verified the expression of miR-155 and its precursors BIC gene with q-PCR in the system of co-culture or HBeAg-stimulated macrophages. Meanwhile, the increased miR-155 expression was positively correlation with serum ALT, AST, and HBeAg levels in AHB patients. Although MAPK, PI3K, and NF-κB signal pathways were all activated during HBeAg treatment, only PI3K and NF-κB pathways were involved in miR-155 expression induced by HBeAg stimulation. Consistently, miR-155 over-expression inhibited production of inflammatory cytokines, which could be reversed by knocking down miR-155. Moreover, we demonstrated that miR-155 regulated HBeAg-induced cytokine production by targeting BCL-6, SHIP-1, and SOCS-1. In conclusion, our data revealed that HBeAg augments the expression of miR-155 in macrophages via PI3K and NF-κB signal pathway and the increased miR-155 promotes HBeAg-induced inflammatory cytokine production by inhibiting the expression of BCL-6, SHIP-1, and SOCS-1.