(WHS-K2.03) The Role of Periostin and Hyaluronan Crosstalk in the Regulation of Wound Fibrosis
Thursday, May 16, 2024
9:15 AM – 10:15 AM East Coast USA Time
Postnatal dermal injury triggers inflammatory and fibrogenic reactions involving feedback signals between ECM mediators that contribute to either wound regeneration or fibrosis. We identified a role for high molecular weight hyaluronan (HMW-HA) in promoting wound regeneration. Upon injury, HA and periostin (POSTN), a matricellular protein, are upregulated. However, HMW-HA expression is not sustained and quickly tapers down in postnatal wounds, while POSTN is sustained. We hypothesize that HA and POSTN crosstalk regulate ECM balance and wound fibrosis. In vitro, murine dermal fibroblasts (mdF) from C57BL/6J mice were stimulated with TGFβ for 24h to promote fibrogenic milieu. HA and POSTN crosstalk was analyzed using gain- and loss-of-function of HA and POSTN signaling. The effect of siRNA knockdown of POSTN on HA synthesis and HA degradation enzymes was assessed. In vivo, 6mm full-thickness stented wounds in C57BL/6J (8wk;n=3) mice were studied with +/- lentiviral overexpression of HMW-HA, and the effect on HA and POSTN expression at d7 and d28 were examined along with changes in collagen and ECM architecture. Human dermal fibroblasts (hdF) from patients with low(LS) and high scar(HS) phenotypes clinically stratified with VSS <3 vs. >6 were tested. p values by ANOVA. TGFβ treatment upregulated both HA-synthase (HAS2) that synthesizes HMW-HA and POSTN gene expression in mdF. To determine if POSTN regulates HAS2 in this model, we knockdown POSTN using siRNA, which significantly reduced the expression of HAS2 (p <.05). Further, mdF treated with 50ng/ml POSTN for 48h showed significantly higher mRNA levels of HAS1 and 2 than controls. To further assess the impact of HAS2 on a reciprocal feedback mechanism that regulates POSTN, HAS2-specific siRNA knockdown was done, which caused a significant increase in POSTN mRNA and protein. In vivo, POSTN was upregulated upon wounding. HMW-HA induction further increased POSTN at d7 post-wounding, but reduced its expression compared to PBS wounds at d28 of the remodeling stage which coincided with reduced collagen and improved ECM architecture in HMW-HA induced wounds at d28. This suggests that sustained HMW-HA production could counter POSTN expression. It is cogent that when HAS2 is low, POSTN expression is upregulated, but when HAS2 expression increases, POSTN is inhibited. Treatment of patient skin fibroblasts LS-hdF vs. HS-hdF with POSTN resulted in differential regulation of HAS2 expression, indicating that each subject responded to POSTN differently, which may contribute to the heterogeneity observed in human wound healing. Our data suggest a mutual HAS2/POSTN interdependence. While injury-induced POSTN is necessary for HAS2 signal induction, the HAS2/HMW-HA then suppresses POSTN to promote wound regeneration. Understanding these basic mechanisms will facilitate improved wound healing and lead to regenerative tissue repair.