HDAC6 inhibition reprograms endothelial and macrophage responses to protect the lung in endotoxemia

Endotoxemia causes pulmonary barrier disruption, endothelial dysfunction, and myeloid-mediated inflammatory responses leading to sepsis-associated acute lung injury. Histone deacetylase 6 (HDAC6) regulates cytoskeletal dynamics and inflammatory signaling; however, its cell-type-specific effects in inflammatory lung injury remain undetermined. We conducted single-cell RNA sequencing in a mouse endotoxemia model to investigate the effects of HDAC6 inhibition on endothelial and macrophage responses. Key findings were confirmed using histology and bulk RNA sequencing studies. In endothelial cells, lipopolysaccharide induced inflammation and STAT pathway activation. HDAC6 inhibition with CAY10603 suppressed these changes, lowered inflammatory and apoptotic scores, and maintained endothelial cells toward earlier pseudotime states. Concurrently, HDAC6 inhibition via CAY10603 treatment restored angiogenesis-associated gene expression (Acadl, Adrb2, Cd24a, Ecm1, and Ptgs1). In macrophages, CAY10603 treatment suppressed lipopolysaccharide-induced interferon, inflammasome, and IL-6/JAK/STAT3 signatures and downregulated key gene expression (Isg15, Ifit1/2, Lcn2, Txnip, and Irf1), maintaining them in less activated states. These findings correlated with reduced alveolar congestion and leukocyte infiltration and suppressed inflammation signatures. Selective HDAC6 inhibition suppresses endothelial activation and macrophage inflammatory programs while promoting angiogenic transcriptional programs, supporting further evaluation of HDAC6-targeted strategies for sepsis-associated lung injury.