ABSTRACT
BACKGROUND: The pathophysiology of Graves' disease (GD) involves imbalances between follicular helper T (Tfh) and follicular regulatory T (Tfr) cells, as well as oxidative stress (OS). Prunella vulgaris L. (Xia Ku Cao, XKC) and its primary bioactive compound, luteolin, are recognized for their potential in treating GD. Yet, the mechanism accounting for the immune-modulatory and antioxidant effects of XKC remains elusive. PURPOSE: This study aims to evaluate the pharmacological effects and elucidate the underlying mechanism of XKC and luteolin in a GD mouse model induced by recombinant adenovirus of TSH receptor A subunit (Ad-hTSHR-289). METHODS: High-Performance Liquid Chromatography-Quadrupole Time-of-Flight Mass Spectrometry (HPLC-QTOF MS) was used to detect the constituents of XKC. The GD model was established through inducing female BALB/c mice with three intramuscular injections of Ad-TSHR-289. Thyroid function, autoantibody and OS parameters were measured by ELISA. Changes of Tfh cells and Tfr cells were detected by flow cytometry. RT-qPCR, Western Blotting, immunohistochemistry were used to explore the related molecular mechanisms. RESULTS: A total of 37 chemical components from XKC were identified by HPLC-QTOF MS, represented by flavonoids, steroids, terpenoids, and luteolin. XKC and luteolin reduced T4, TRAb levels and facilitated the recovery from thyroid damage in GD mice. Meanwhile, XKC and luteolin effectively alleviated OS by decreasing the levels of MDA, NOX2, 4-HNE, 8-OHdG, while increasing GSH level. Flow cytometry showed that XKC and luteolin restored the abnormal proportions of Tfh/Tfr and Tfh/Treg, and the mRNA levels of IL-21, Bcl-6 and Foxp3 in GD mice. In addition, XKC and luteolin inhibited PI3K, Akt, p-PI3K and p-Akt, but activated Nrf2 and HO-1. CONCLUSION: XKC and luteolin could inhibit the development of GD in vivo by rebalancing Tfh/Tfr cells and alleviating OS. This therapeutic mechanism may involve the Nrf2/HO-1 and PI3K/Akt signaling pathways. Luteolin is the main efficacy material basis of XKC in countering GD. For the first time, we revealed the mechanism of XKC and luteolin in the treatment of GD from the perspective of autoimmune and OS.
ABSTRACT
ETHNOPHARMACOLOGICAL RELEVANCE: For numerous years, the Xiehuo Xiaoying decoction (XHXY), a traditional Chinese medicine formula, has demonstrated substantial promise in treating Graves' disease (GD) in clinical settings, showcasing significant potential. However, the therapeutic mechanism and efficacy material basis of XHXY remains obscure. AIM OF THE STUDY: This work aims to investigate the underlying mechanisms and to study the efficacy material basis of XHXY in anti-GD effect using a combination of TMT quantitative proteomics and molecular docking method. MATERIALS AND METHODS: GD model was initiated by administering Ad-TSH289. Subsequently, the mice underwent a four-week regimen that included oral gavage of XHXY at doses of 17 g/kg·d and 34 g/kg·d, along with intraperitoneal injections of Gentiopicroside (GPS). Utilizing the principles of pharmacological chemistry in traditional Chinese medicine, we employed high-performance liquid chromatography quadrupole time-of-flight mass spectrometry (HPLC-QTOF/MS) to discern prescribed prototype composition of XHXY in serum samples from mouse. TMT proteomics research provided evidence of XHXY's putative targets and important pathways in vivo. The binding activity of probable action targets and prototype composition was detected by molecular docking. Finally, Immunohistochemistry (IHC) and TUNEL staining were used to verify the mechanism of XHXY and GPS in anti-GD. RESULTS: XHXY and GPS alleviated GD by ameliorating the pathological changes and reducing thyroxine and TRAb levels. In mouse serum, a total of 31 prototypical XHXY ingredients were detected, and the majority of these components were from monarch and minister medicine. Proteomics study results indicated that the XHXY may mainly regulate targets including FAS-associated death domain protein (FADD), Apolipoprotein C-III, etc. and main pathways are Apoptosis, Cholesterol metabolism, TNF signalling pathway, etc. Strong binding activity of the prototypical active ingredient and GPS towards FADD, Caspase 8, and Caspase 3 was demonstrated by molecular docking. XHXY and its primary component, GPS, elevated the expression of FADD, Caspase 8, and Caspase 3, and enhance apoptosis in thyroid cells, as lastly validated by TUNEL and IHC staining. CONCLUSIONS: XHXY exhibits a favorable therapeutic effect in treating GD by promoting apoptosis in thyroid cells through the upregulation of FADD, Caspase 8, and Caspase 3 expression. And GPS is the main efficacy material basis for its therapeutic effect in anti-GD.
