The Chinese herbal formula Zhibai Dihuang Granule treat Yin-deficiency-heat syndrome rats by regulating the immune responses

Ethnopharmacological relevance: Zhibai Dihuang Granule (ZDG), a traditional Chinese medicine (TCM) made from eight Chinese herbs, has been classically used to treat Yin-deficiency-heat (YDH) syndrome. ZDG is well known with the therapeutic efficacy of nourishing Yin and decreasing internal heat in clinic, but the mechanism of ZDG's therapeutic effect is still not clear. Materials and methods: High doses of triiodothyronine (T3) were given intraperitoneally to induce Hyperthyroid YDH syndrome in SD rats. The animals were then treated with ZDG for one week. The iTRAQ-coupled with two-dimensional liquid chromatography-tandem mass spectrometry (2D LC-MS/MS) technique was used to screen the differentially expressed serum proteins between ZDG treated rats and YDH syndrome rats. The differentially expressed proteins were analyzed by bioinformatics method and were verified by enzyme-linked immunosorbent assay (ELISA). Results: A total of 55 differentially expressed proteins were identified, including 23 up-regulated proteins (> 1.25 fold, p < 0.05) and 32 down-regulated proteins (< 0.80 fold, p < 0.05). Among the differentially expressed proteins, 26 proteins returned to normal after ZDG treatment. Bioinformatics analysis showed that these proteins were mainly involved in immune response, including regulation of immune system process, complement activation, and humoral immune response mediated by circulating immunoglobulin. ELISA revealed significantly increased levels of Zinc-alpha-2-glycoprotein (Azgpl), L-selectin, C-reactive protein (Crp), Plasminogen (Pig), Kininogen 1 (Kngl), and significantly decreased levels of Mannose binding lectin 2 (Mb12) and Complement Clqb chain (Clqb) in ZDG treated rats compared with YDH syndrome rats. Bioinformatics analyses indicated that Azgpl participated in antigen processing and presentation, Crp, Clqb, and Mb12 were involved in complement activation, while L-selectin, Plg, and Kngl were involved in regulating the inflammatory response. Conclusions: Our study provides experimental evidence to understand the therapeutic mechanism of ZDG in YDH syndrome. The results suggested that ZDG may regulate the complement activation and inflammatory response, and promote the ability to recognize antigens to alleviate YDH syndrome.