Nitric Oxide Scavenging Alleviates Scar Pruritus by Inhibiting S-Nitrosylation of Transient Receptor Potential Channels and Limiting Calcium Influx

Scar pruritus, a common and debilitating symptom in burn patients, significantly impacts quality of life. This study investigates the therapeutic potential of nitric oxide (NO) scavenging in alleviating scar pruritus by targeting the S-nitrosylation (SNO) of transient receptor potential (TRP) channels, which play a crucial role in pruritus sensation and transmission. We hypothesized that NO-induced SNO of TRP channels mediates scar pruritus and explored the effects of NO scavengers on pruritus-related features in scar tissue. We used hypertrophic scar (HS) and normal skin (NS) tissues from patients, HaCaT keratinocyte cell lines for in vitro studies, and a murine model for in vivo studies. NO scavengers, a combination of hemoglobin (HB) and N(omega)-nitro-L-arginine methyl ester (L-NM), were applied to assess their effects on NO, SNO, TRP channels, and pruritogen expression. RNA sequencing and proteomics were conducted to analyze differential gene and protein expression, respectively. NO levels, SNO, and calcium influx were measured using fluorescence probes, immunohistochemistry, and calcium imaging techniques. Scar tissues exhibited higher levels of pruritogens, NO, and SNO compared to normal skin, with increased expression of TRPV1, TRPV3, TRPV4, and TRPA1. NO scavenging reduced scratch behavior in mouse models of scar pruritus, decreased NO and SNO levels, and downregulated the expression of TRP channels. In vitro, NO scavengers inhibited SNO of TRPV1 and limited intracellular calcium influx in HaCaT cells stimulated with substance P (SP). Additionally, NO scavenging reduced the secretion of pruritus mediators such as thymic stromal lymphopoietin (TSLP), nerve growth factor (NGF), and interleukin-31 (IL-31). NO scavenging effectively alleviates scar pruritus by inhibiting the SNO of TRP channels, particularly TRPV1, and consequently limiting the influx of intracellular calcium ions. This study provides a novel therapeutic approach for scar pruritus and highlights the potential of NO scavengers in modulating itch sensation pathways.