ABT-263 Reduces Hypertrophic Scars by Targeting Apoptosis of Myofibroblasts.

Futing Shu,Xiaolan Yang,Yongjun Zheng,Shichu Xiao,Yongqiang Xiao,Zhaofan Xia,Chenjian Zhong

doi:10.3389/fphar.2020.615505

Abstract

Background: Inhibiting proliferation and inducing apoptosis of myofibroblasts is becoming one of the promising and effective ways to treat hypertrophic scar. ABT-263, as an orally bioavailable BCL-2 family inhibitor, has showed great antitumor characteristics by targeting tumor cell apoptosis. The objective of this study was to explore whether ABT-263 could target apoptosis of overactivated myofibroblasts in hypertrophic scar. Methods: In vivo, we used ABT-263 to treat scars in a rabbit ear scar model. Photographs and ultrasound examination were taken weekly, and scars were harvested on day 42 for further Masson trichrome staining. In vitro, the expression levels of BCL-2 family members, including prosurvival proteins, activators, and effectors, were detected systematically in hypertrophic scar tissues and adjacent normal skin tissues, as well as in human hypertrophic scar fibroblasts (HSFs) and human normal dermal fibroblasts (HFBs). The roles of ABT-263 in apoptosis and proliferation of HSFs and HFBs were determined by annexin V/PI assay, CCK-8 kit, and cell cycle analysis. Mitochondrial membrane potential was evaluated by JC-1 staining and the expression of type I/III collagen and α-SMA was measured by PCR, western blotting, and immunofluorescence staining. Furthermore, immunoprecipitation was performed to explore the potential mechanism. Results: In vivo, ABT-263 could significantly improve the scar appearance and collagen arrangement, decrease scar elevation index (SEI), and induce cell apoptosis. In vitro, the expression levels of BCL-2, BCL-XL, and BIM were significantly higher in scar tissues and HSFs than those in normal skin tissues and HFBs. ABT-263 selectively induced HSFs apoptosis by releasing BIM from binding with prosurvival proteins. Moreover, ABT-263 inhibited HSFs proliferation and reduced the expression of α-SMA and type I/III collagen in a concentration- and time- dependent manner. Conclusion: HSFs showed increased mitochondrial priming with higher level of proapoptotic activator BIM and were primed to death. ABT-263 showed great therapeutic ability in the treatment of hypertrophic scar by targeting HSFs.

Highlights

Hypertrophic scar affects millions of patients, children and burn victims, resulting in long-term physical dysfunction and psychological stress (Sheridan et al, 2000; Cen et al, 2015)
We explored the therapeutic effects of ABT-263 on hypertrophic scar in vivo and further explored related mechanisms by in vitro experiments, with a focus on the direct effects of ABT-263 on targeting myofibroblasts apoptosis
To evaluate the effect of ABT-263 on cell apoptosis in scar tissue, we performed TUNEL staining on rabbit ear-tissue sections

Summary

Introduction

Hypertrophic scar affects millions of patients, children and burn victims, resulting in long-term physical dysfunction and psychological stress (Sheridan et al, 2000; Cen et al, 2015). There are a variety of treatments for hypertrophic scars, such as resection, corticosteroid injection, compression, and laser treatment. Myofibroblasts are responsible for tissue contraction and excessive extracellular matrix (ECM) secretion during hypertrophic scar formation, leading to stiffness, compression, and loss of joint mobility. Strategies that inhibit myofibroblast proliferation and promote myofibroblast apoptosis are effective ways for treating hypertrophic scar (Shi et al, 2018; Zhou et al, 2018). Inhibiting proliferation and inducing apoptosis of myofibroblasts is becoming one of the promising and effective ways to treat hypertrophic scar. The objective of this study was to explore whether ABT-263 could target apoptosis of overactivated myofibroblasts in hypertrophic scar

Objectives

Methods

Results

Conclusion