TY - JOUR T1 - HDAC inhibitors decrease TLR7/9-mediated human plasmacytoid dendritic cell activation by interfering with IRF-7 and NF-κB signaling JF - bioRxiv DO - 10.1101/2020.05.09.085456 SP - 2020.05.09.085456 AU - Dante B. Descalzi-Montoya AU - Jihong Dai AU - Sukhwinder Singh AU - Patricia Fitzgerald-Bocarsly Y1 - 2020/01/01 UR - http://biorxiv.org/content/early/2020/05/09/2020.05.09.085456.abstract N2 - Histone deacetylase inhibitors (HDACi) are epigenome modulating molecules that target histone and non-histone proteins and have been successfully used to target many types of cancer and immunological disorders. While HDACi’s effects on nuclear histone deacetylases are well characterized, their effect on non-nuclear, cytoplasmic molecules requires further investigation. In the current study we characterized the effects of class I/II HDACi, specifically, TSA, MS-275, and SAHA, on plasmacytoid dendritic cell (pDC) biology upon viral activation via the TLR7/9 pathway. TSA, MS-275, and SAHA, down-modulated the induction of IFN-α and TNF-α upon Influenza A virus (IAV; TLR7 signaling) and Herpes Simplex 1 (HSV-1; TLR9 signaling) stimulation in primary pDC. The HDACi inhibitory effect was more prominent for IAV-mediated responses than for HSV-1. While IFN-α induction was not associated with inhibition of IRF-7 upregulation in the presence of TSA or MS-275, IRF-7 upregulation was affected by SAHA, but only for IAV. Furthermore, TSA, but not MS-275, inhibited TLR7/9-induced expression of maturation markers, CD40, and CD86, but not CD40. In addition, HDACi treatment increased virally-induced shedding of CD62L. Mechanistically, TSA, MS-275, SAHA significantly decreased early IRF-7 and NF-κB nuclear translocation, which was preceded by a decline in phosphorylation of IRF-7 at Ser477/479 and NF-κB p-p65, except for MS-275. In summary, we propose that broad HDACi, but not class I HDACi, treatment can negatively impact early TLR7/9-mediated signaling, namely, the disruption of IRF-7 and NF-κB activation and translocation that lead to deleterious effects on pDC function.Competing Interest StatementThe authors have declared no competing interest. ER -