Inhibitory effects of JQ1 on listeria monocytogenes-induced acute liver injury by blocking BRD4/RIPK1 axis

Listeria monocytogenes (LM) is a facultative intracellular bacterium that causes septicemia-associated acute hepatic injury. However, the pathogenesis of this process is still unclear, and there is still a lack of effective therapeutic strategy for the treatment of LM-induced liver injury. In this study, we attempted to explore the effects of necroptosis on bacterial-septicemia-associated hepatic disease and to explore the contribution of JQ1, a selective BRD4 inhibitor, to the suppression of necroptosis and inhibition of LM-triggered hepatic injury. The results indicated that hepatic BRD4 was primarily stimulated by LM both in vitro and in vivo, along with significantly up-regulated expression of receptor-interacting protein kinase (RIPK)-1, RIPK3, and p-mixed lineage kinase-like (MLKL), showing the elevated necroptosis. However, JQ1 treatment and RIPK1 knockout were found to significantly alleviate LM-induced acute liver injury. Histological alterations and cell death in hepatic samples in LM-infected mice were also alleviated by JQ1 administration or RIPK1 deletion. However, JQ1-improved hepatic injury by LM was abrogated by RIPK1 over-expression, suggesting that the protective effects of JQ1 took place mainly in an RIPK1-dependent manner. In addition, LM-evoked inflammatory response in liver tissues were also alleviated by JQ1, which was similar to the findings observed in mice lacking RIPK1. The anti-inflammatory effects of JQ1 were diminished by RIPK1 over-expression in LM-infected mice. Finally, both in vivo and in vitro experiments suggested that JQ1 dramatically improved hepatic mitochondrial dysfunction in LM-injected mice, but this effect was abolished by RIPK1 over-expression. In conclusion, these results indicated that suppressing BRD4 by JQ1 could ameliorate LM-associated liver injury by suppressing necroptosis, inflammation, and mitochondrial dysfunction by inhibiting RIPK1.