HDAC6 inhibitor accelerates wound healing by inhibiting tubulin mediated IL-1β secretion in diabetic mice.

Delayed wound healing in diabetes is characterized by sustained activation of inflammasome and increased expression of IL-1β in macrophages. Identification and validation of novel pathways to regulate IL-1β expression will provide therapeutic targets for diabetic wounds. Here we report sustained over-expression of histone deacetylase 6 (HDAC6) in wounds of diabetic mice and its role in delayed wound healing. Topical application of HDAC6 inhibitor; Tubastatin A (TSA) gel promoted the wound healing in diabetic mice. TSA hydrogel reduced the infiltration of neutrophils, T-cells and macrophages in the early phase of wound healing. TSA treatment promoted the wound healing by inducing collagen deposition, angiogenesis (CD31) and fibrotic factors (TGF-β1) in the late phase of healing. Protein analysis of the diabetic wounds treated with TSA showed increased acetylated α-tubulin and decreased levels of mature IL-1β with no significant effect on the expression of pro-IL-1β, pro-caspase-1 and active caspase-1. In in vitro assays, macrophages exhibited upregulation of HDAC6, IL-1β and downregulation of IL-10 upon stimulation with high glucose and LPS. TSA inhibited the IL-1β secretion and promoted IL-10 in stimulated macrophages with high glucose and LPS. Further investigations showed that TSA inhibits IL-1β release by inhibiting tubulin dependent lysosomal exocytosis without affecting its transcription and maturation. Nocodazole (known acetylation inhibitor) pre-treatment inhibited TSA effect on IL-1β secretion in high glucose stimulated macrophages. Overall, our findings indicate that sustained HDAC6 expression in diabetic wounds contributes to impaired healing responses and HDAC6 may represent a new therapeutic target for diabetic wounds.
Competing Interests: Declaration of competing interest With the submission of this manuscript we would like to undertake that the above mentioned manuscript has not been published elsewhere, accepted for publication elsewhere or under editorial review for publication elsewhere; and that my Institute's BITS-Pilani, Hyderabad campus and co-authors are fully aware of this submission. The authors declare no conflicts of interest.
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