Bletilla striata polysaccharide as a dual-hit biologic: Orchestrating pyroptosis inhibition and trained immunity for...

Chronic wounds, particularly diabetic foot ulcers (DFUs), represent a stalled inflammatory state driven by excessive NLRP3-mediated pyroptosis and defective innate immune memory. Bletilla striata polysaccharide (BSP), a neutral glucomannan from the orchid Bletilla striata, has emerged as a promising immunomodulatory candidate. This review critically examines the pharmacological potential of BSP, focusing on its structure-activity relationships (SAR)-specifically how extraction-dependent variations in molecular weight, mannose:glucose ratio, and degree of acetylation dictate receptor recognition. Emerging preclinical evidence suggests a "dual-hit" mechanism: BSP directly inhibits NLRP3 inflammasome assembly and gasdermin D-mediated pyroptosis to salvage tissue, while its degradation fragments induce epigenetic and metabolic reprogramming (trained immunity) in myeloid cells to prevent recurrence. Crucially, we discuss the "double-edged" nature of this immune training, weighing its benefits in antimicrobial defense against the theoretical risks of maladaptive systemic inflammation. We further analyze translational barriers, including the "quality-by-design" approaches needed to overcome batch variability and the regulatory pathway for botanical biologics. This review positions BSP not merely as a dressing, but as a sophisticated modulator of the pyroptosis-trained immunity axis, necessitating rigorous clinical validation to define its therapeutic window.