Investigation of the Mechanism of Cold Hyperalgesia in KOA Mice Relieved by Shangke Lengtongtie Based on HMGB1/CXCL12/CXCR4 Signaling Axis

OBJECTIVE To explore the intervention mechanism of Shangke Lengtongtie on cold hyperalgesia in KOA mice based on the HMGB1/CXCL12/CXCR4 signaling axis.

METHODS Monosodium iodoacetate (MIA) was used for the intra-articular injection into the knee joint to establish mice model of knee osteoarthritis (KOA). Peripheral blood monocytes were extracted from mice, cultured, and then reinfused into the tail vein of the mice. Subsequently, in vivo animal imaging was used to observe the recruitment sites of these monocytes. The cold hyperalgesia threshold was measured at various time points in each group of mice. Hematoxylin and eosin (HE) staining was used to evaluate the level of synovial pathological changes. ELISA was employed to detect the expression of inflammatory factors IL-1β, TNF-α, and pain mediators CGRP and Substance P in mouse serum. Western blot and qPCR methods were used to detect the protein and gene expression of cold hyperalgesia-related indicators such as TRPA1, TRPM8, HMGB1, CXCL12, CXCR4, Collagen Ⅰ, and Netrin-1 in synovial tissue, as well as DCC in dorsal root ganglia (DRG) tissue.

RESULTS In vivo imaging showed that after the monocytes were reinfused into KOA mice, they were recruited to the knee joint area, with the HMGB1 group exhibiting a greater recruitment of circulating monocytes at the knee joint. Additionally, compared to the control group, the KOA group and HMGB1 group showed inflammatory pathological changes in the synovium, increased expression of serum inflammatory factors and pain mediators, reduced cold hyperalgesia threshold, and upregulated protein and gene expression of cold hyperalgesia-related indicators in synovial and DRG tissues. The changes were more significant in the HMGB1 group compared to the KOA group (P < 0.05). After treatment with Shangke Lengtongtie or GL intervention, synovial inflammation was alleviated, serum inflammatory factors and pain mediators decreased, cold hyperalgesia threshold increased, and the upregulation of cold hyperalgesia-related indicator protein and gene expression levels was significantly reversed (P < 0.05).

CONCLUSION Shangke Lengtongtie exerts a beneficial effect on the mitigation of synovitis and cold hyperalgesia in KOA mice, a therapeutic mechanism that possibly mediated through the inhibition of the HMGB1/CXCL12/CXCR4 signaling axis.