From RCT to mechanistic study: ATRA reverses myofibroblast activation by reprogramming glucose metabolism via HIC1 and PCK1/2 to attenuate hypertrophic scar formation

Background Abnormal glucose metabolism often contributes to myofibroblast activation and the pathogenesis of skin fibrotic diseases. All-trans retinoic acid (ATRA), the active component of tretinoin cream, can regulate glucose metabolism and activate myofibroblasts. Importantly, investigating the potential of ATRA to inhibit myofibroblast activation by modulating glucose metabolism could reveal the translational significance of ATRA in attenuating hypertrophic scar (HS) formation. Methods We first conducted a multicenter, double-blind, randomized controlled trial (RCT) to compare the effects of tretinoin cream with those of the first-line medication, silicone gel. In the mechanistic study, the characteristics of glucose metabolic reprogramming and the activation of hypertrophic scar fibroblasts (HSFs) after ATRA treatment were identified through multi-omics profiling, complemented by glucose metabolism assays and functional validations. Besides, genetic overexpression targeting the potential downstream molecules of ATRA, including hypermethylated in cancer 1 (HIC1), phosphoenolpyruvate carboxykinase (PCK)1, and PCK2, was conducted in vitro in HSFs and in vivo in skin fibroblasts of Col1a2-CreER mice. Results Our RCT demonstrated that tretinoin cream is non-inferior to silicone gel in preventing HS formation, with the absolute risk difference of incidence rates [–8.65% 90% two-sided confidence interval (CI) –23.03 to 5.74] and in decreasing scar thickness [(2856.20±211.83) μm vs. (1664.57±273.50) μm], attributing to the reduction in HSF proliferation and the proportion of myofibroblasts. Moreover, tretinoin cream effectively mitigated HS formation in both mice and rabbits without impeding normal wound healing. Mechanistically, HSFs underwent glucose reprogramming, characterized by increased aerobic glycolysis, which facilitated the transition of HSFs to myofibroblasts and their proliferation. However, ATRA upregulated HIC1, PCK1, and PCK2 expression through retinoic acid receptor alpha (RARα) activation, thereby inhibiting the fibrotic phenotypes of HSFs by suppressing aerobic glycolysis and facilitating gluconeogenesis. The fibroblast-specific overexpression of HIC1, PCK1, or PCK2 in Col1a2-CreER mice significantly reduced myofibroblast activation and hypertrophic scarring. Conclusions Our study not only substantiated that topical tretinoin cream could serve as an effective strategy to prevent HSs in clinical settings, but also established ATRA as a regulator of glucose metabolism. Importantly, ATRA/RARα-mediated glucose reprogramming was identified as a potential therapeutic target for attenuating HS formation. Trial registration ChiCTR, ChiCTR2500097242. Registered on 14 Feb, 2025. Available from https://www.chictr.org.cn/bin/project/edit?pid=220146.