Histone acetylation alteration by KAT6A inhibitor WM-1119 suppresses IgE-mediated mast cell activation and allergic inflammation via reduction in AP-1 signaling

Activation of immunoglobulin E (IgE)-associated mast cells (MCs) triggers the onset of pro-inflammatory signals associated with type I allergic diseases. Although histone acetylation changes have been associated with inflammatory diseases, the impact of lysine-acetyltransferase (KAT) inhibitors on IgE-mediated MCs function is unclear. Potential anti-allergic effects of the KAT6A inhibitor WM-1119 on IgE-mediated MCs activation and allergic inflammation were examined in this study. WM-1119 was observed to reduce IgE-mediated degranulation in rat basophilic leukemia-2H3 cells (RBLs) and murine bone marrow-derived mast cells (BMMCs), as demonstrated by reduced the release of β-hexosaminidase (β-hex)   or histamine   (HA) and decreased inflammatory cytokines. Additionally, WM-1119 attenuated allergic responses in IgE-induced passive cutaneous anaphylaxis (PCA) and active systemic anaphylaxis (ASA) mice. No WM-1119 effects on histamine-induced hypothermia in mice were observed. Mechanically, WM-1119 reduced levels of histone H3 lysine 14 acetylation (H3K14ac) and H3K27ac, while also reducing IgE-induced MAPK or NF-κB activity. Moreover, WM-1119 reduced activator protein-1 (AP-1) activity in a manner involving inhibition of c-Fos transcription and translation together with decreased AP-1 binding of its downstream promoters. KAT6A knockdown in MCs also reduced AP-1 activity by inhibiting c-Fos expression. H3K14ac enrichment in the Fos promoter was observed, indicating that H3K14ac may regulate c-Fos expression. In conclusion, KAT6A inhibition or knockdown was shown to reduce IgE-mediated MCs activation and allergic inflammation through a mechanism involving changes in c-Fos expression and downstream AP-1 activity consequent to down-regulation of histone acetylation. KAT6A inhibition may represent a new treatment strategy for suppressing MCs in treating allergic diseases.