C105-05 Targeting Brd4 Attenuates Acute Lung Injury by Regulating Panoptosis in Alveolar Macrophages

Abstract Background Acute respiratory distress syndrome (ARDS) is a life-threatening respiratory disorder characterized by severe inflammation and diffuse acute lung injury (ALI). PANoptosis, a recently identified form of programmed cell death integrating pyroptosis, apoptosis, and necroptosis, has been implicated in the inflammatory responses driving cytokine storm and lung injury. Bromodomain-containing protein 4 (BRD4), a key member of the bromodomain and extra-terminal (BET) family, functions in diverse pathophysiological processes. This study aimed to elucidate the role of BRD4 in macrophage PANoptosis during ARDS/ALI. Methods Bone marrow-derived macrophages (BMDMs) from wild-type (WT) and myeloid-specific BRD4 conditional knockout (BRD4-CKO) mice were stimulated with TNF-α and IFN-γ. RNA sequencing was performed to analyze differentially expressed gene between WT and BRD4-deficient macrophages. An LPS-induced ALI model was established by intratracheal instillation in WT and BRD4-CKO mice to evaluate the effects of BRD4 deletion on lung injury and macrophage PANoptosis. The selective BRD4 inhibitor JQ1 was used to assess the therapeutic potential of pharmacologic inhibition in vivo. Results RNA-seq analysis revealed that BRD4 plays a critical role in TNF-α/IFN-γ-induced macrophage PANoptosis. BRD4 deletion significantly suppressed cytokine-induced PANoptotic signaling. Molecular docking and co-immunoprecipitation demonstrated a strong interaction between BRD4 and interferon regulatory factor-1 (IRF1), forming a transcriptional complex that promotes ZBP1 expression and ZBP1-mediated PANoptosis. In vivo, both BRD4-CKO and JQ1-treated mice exhibited markedly attenuated LPS-induced lung injury, reduced cytokine levels, and downregulated ZBP1 expression and PANoptosis in alveolar macrophages compared with controls. Conclusions BRD4 acts as a key transcriptional regulator linking cytokine storm and lung injury by recruiting IRF1 to activate ZBP1-mediated PANoptosis in alveolar macrophages. Genetic or pharmacologic inhibition of BRD4 alleviates LPS-induced ALI, highlighting BRD4 as a promising therapeutic target for ARDS. This abstract is funded by: National Key Research and Development Program of China (2022YFC2504401)