Huanglian Jiedu plaster (HJP) is a kind of Chinese patent medicine that contains four medicinal plants. It has been clinically proven to be beneficial for the treatment of tumor-associated radiation dermatitis. However, the underlying mechanism of HJP on radiation dermatitis remains unclear.

This study aims to investigate the therapeutic effect of HJP on X-ray-induced radiation dermatitis, and how HJP improves the inflammatory response and skin damage of radiation dermatitis.

In this study, We selected a case of esophageal cancer as a clinical demonstration of the efficacy of radiation dermatitis. The patient received a total radiation dose of 7000cGY, and treatment by HJP for 14 days.RD mouse models were established through continuous irradiation with X-ray (800cGY) on the right hind limb of mice for 5 days, and the treatment group mice was applied HJP to the irradiated skin for 15 days from modeling. An inflammatory cellular model was induced through irradiation with X-ray (100cGY) in JB6 cells and a co-culture system of JB6 cell and macrophage was established to examine the effect and mechanism of HJP on the inflammatory interaction of these two cells. The activation of HMGB1-TLR4-NF-κB signaling pathway, and the levels of epidermal injury related factors and inflammatory cytokins were subsequently detected.

The results showed that HJP can significantly alleviate X-ray-induced skin injury, inhibiting skin inflammation and reducing the expression of inflammatory cytokins (IL-1β, IL-6, TNF-α) and epidermal damage related factors (Integrin β1, CXCL9 and Cytokeratin17), as well as significantly down-regulated the protein level of HMGB1 (a key DAMPs factor) in vivo and in vitro. Cell co-culture experiments demonstrated that HMGB1 released from X-ray-induced JB6 cells can promote inflammatory response of macrophage, which then feedback aggravate epithelial cell damage, notably, HJP can significantly improve radiation skin lesion by inhibiting HMGB1-mediated inflammatory interaction between epithelial cells and macrophages.

In summary, these findings indicated the role of HJP in the treatment of RD by inhibiting the inflammatory interaction between macrophage and JB6 cells mediated by HMGB1, which may provide a reliable therapeutic method for RD. Furthermore, HMGB1 may be an effective target for HJP to inhibit inflammation and ameliorate skin damage in RD.