Effects of MRSA and FTY720 S-phosphonate on H3K9 acetylation in human lung endothelial cells

Methicillin-resistant Staph. Aureus (MRSA) is a common cause of severe pneumonia and sepsis that can lead to Acute Respiratory Distress Syndrome (ARDS). MRSA causes lung endothelial cell (EC) dysfunction, a critical step in the pathogenesis and progression of lung injury. Our previous studies have demonstrated that FTY720 S-phosphonate (Tysiponate, Tys), an analog of sphingosine-1-phosphate, ameliorates MRSA-induced lung EC activation and barrier disruption (PMID: 35015568). To advance our mechanistic understanding of MRSA and Tys effects on lung EC, we investigated associated epigenetic changes. Specifically, we studied histone lysine acetylation, which is a central epigenetic alteration that has been linked to gene transcription and functional regulation of endothelial responses to inflammatory stimuli. We therefore determined the effects of MRSA exposure in the presence or absence of Tys on lung EC acetylation at the 9th lysine residue of the histone H3 protein (H3K9ac), which is an important chromatin modification associated with active promoters and gene activation. ChIP-seq analysis was employed to perform an unbiased genome-wide profiling of H3K9ac epigenetic patterns in human lung EC. This analysis identified multiple genes that are differentially targeted by acetylation when EC are exposed to MRSA±Tys. Chromatin immunoprecipitation sequencing (Chip-Seq) for histone modification H3K9 acetylation in human pulmonary artery endothelial cells treated with heat-killed methicillin resistant Staph Aureus (HK-MRSA), Tysiponate (FTY720 S-phosphonate; S1P analogue),or HK-MRSA +Tys for 30 min. Cells treated only with vehicle were used as control.