Gluconic acid alleviates hypertrophic scar formation through binding PLOD1, reducing p-AKT signaling and activating autophagy

Background

Hypertrophic scarring represents a major clinical challenge worldwide, with current treatment strategies showing limited effectiveness. Gluconic acid (GLA), a naturally occurring glucose metabolite found in fruits, honey, kombucha tea, and wine, may provide new approach for scar treatment.

Purpose

This study aimed to investigate the anti-scarring properties of GLA and underlying molecular mechanisms.

Study design

A comprehensive experimental study combined in vitro hypertrophic scar fibroblasts and in vivo rabbit ear scar model assays.

Methods

Hypertrophic scar fibroblasts were treated with GLA. Cell counting kit-8 (CCK-8) and flow cytometry were used to evaluate cell viability and apoptosis. The collagen and ACTA2 (actin alpha 2, smooth muscle) expressions were analyzed by qPCR and western blot. A rabbit ear scar model was applied to assess GLA’s effects on scar formation and collagen deposition. Transcriptome sequencing, pull-down assays, western blotting and rescue experiments using AKT agonist SC79 were employed to identify GLA-regulated pathways. Molecular docking, pull-down, cellular thermal shift assays and co-localization studies were used to assess GLA’s interaction with PLOD1 (procollagen-lysine, 2-oxoglutarate 5-dioxygenase 1). E64d, MG132 and QX77 were added to analyze GLA’s function mechanisms on PLOD1 protein expression. Autophagy activation was evaluated through autophagic flux assay, transmission electron microscopy and autophagy related protein expression analysis. Mitochondrial membrane potential was detected by JC-1 staining.

Results

GLA suppresses collagen and ACTA2 expressions and exerted a mild inhibitory effect on cell proliferation or apoptosis in hypertrophic scar fibroblasts. And it diminishes scar formation and collagen content in the rabbit ear scar model. AKT (protein kinase B) and phosphorylated AKT (p-AKT) levels were significantly reduced after GLA treatment. Rescue experiments confirmed that GLA’s effects are mediated through the AKT pathway. Moreover, GLA interacts with PLOD1, resulting in its autophagy-lysosomal degradation. Additionally, GLA treatment activated autophagy, reduced mTOR protein expressions, and had no significant effect on mitochondrial membrane depolarization, further contributing to its anti-scarring effects.

Conclusion

Our findings demonstrate that GLA attenuates hypertrophic scarring through multi-modal mechanisms involving PLOD1 targeting, AKT/mTOR pathway inhibition, and autophagy activation. This study provides both mechanistic insights and therapeutic potential for GLA in scar treatment.