HDAC9 and acute respiratory distress syndrome: Classes of epigenetic modulators such as HDAC inhibitors, PAD4 inhibitors, DNA methyltransferase (DNMT) inhibitors, and protease-activated receptor-1 (PAR1) antagonists have been effective in preclinical models of ARDS, ALI, COVID-19, and related inflammatory conditions; additionally, some therapeutic agents are already in clinical use for other diseases; these therapeutic agents and their targets are outlined in Table 1 [45].