Targeting macrophage function with botulinum toxin: a novel translational strategy for preventing and treating...

Pathological scars, including hypertrophic scars and keloids, remain a significant clinical challenge due to the limitations of current treatments. Botulinum neurotoxin type A (BTX-A) has emerged as a transformative therapy, but its efficacy has often been narrowly attributed to its canonical function of reducing mechanical tone through muscle paralysis. This review synthesises extensive evidence to propose a more comprehensive, macrophage-centric framework for explaining the potent antifibrotic effects of BTX-A. We propose that the mechanism is rooted in two profoundly synergistic pathways of macrophage function. Established indirect pathways involve BTX-A creating mechanically and neurogenetically quiescent microenvironments. This action prevents pathologic extracellular matrix sclerosis and removes key stimuli that drive macrophage polarization toward a sustained profibrotic M2 phenotype. To complement this, we explored a highly plausible direct pathway by which BTX-A might be internalized by macrophages to enzyme digest SNARE proteins such as SNAP-25 and SNAP-23. This would directly compromise the cellular machinery responsible for the secretion of key profibrotic mediators, particularly TGF-β1. Together, these indirect environmental reprogramming and direct cellular interventions constitute a constitute a multiprilled attack to systematically dismantle the self-perpetuating feedback loop of fibrosis. By positioning macrophages as the central convergence point for these pleiotropic effects, this unified model provides a strong mechanistic basis for the clinical success of BTX-A and a clear pathway for optimizing treatment regimens and developing new combination strategies.