Targeting tryptophan metabolism reveals Clematichinenoside AR alleviates triptolide-induced hepatotoxicity.

Liver toxicity induced by Triptolide (TP) has limited its clinical application on rheumatoid arthritis (RA). Saponins have been proved as an efficacious remedy to mitigate hepatotoxicity. However, the mechanism of reducing hepatotoxicity by saponins intervention remains incompletely characterized. Tryptophan (Trp) metabolites activate transcriptional regulators to mediate host detoxification responses. Our study aimed to investigate whether Clematichinenoside AR (C-AR) could attenuate TP-induced liver damage by regulating Trp metabolism. We used targeted metabolomics to quantify Trp metabolites in the serum and liver samples of collagen-induced arthritis rats treated by TP. Multiple comparison analyses helped the evaluation of promising biomarkers. The pronounced changed levels of Trp, indole acetic acid, and indole-3-carboxaldehyde in the serum and indole acetic acid, indole, and tryptamine in the liver are relevant to TP-induced liver injury. Intervention with C-AR could relieve TP-induced hepatotoxicity evidenced by ameliorative serum parameters and hepatic histology. In addition, C-AR regulated the levels of these indoles biomarker candidates to normal. Therapeutic modulation with natural compounds might be a useful clinical strategy to ameliorate toxicity induced by TP. Deciphering Trp metabolism will facilitate a better understanding of the pathogenesis of diseases and drug responding.

Succinate induces synovial angiogenesis in rheumatoid arthritis through metabolic remodeling and HIF-1α/VEGF axis.

BACKGROUND AND PURPOSE: In response to hypoxic succinate accumulates in arthritis synovium, however, the implication is little known. This study aims to investigate whether succinate could act as a metabolic signal linking metabolic alternation with angiogenesis in arthritis synovium. EXPERIMENTAL APPROACH: The interaction between elevated succinate and VEGF production was examined in endothelial cells. Succinate production, HIF-1α induction and angiogenesis in the hypoxic synovium of collagen-induced arthritis rats were also investigated. KEY RESULTS: Intracellular succinate promoted VEGF production and induced angiogenic response dependent on HIF-1α induction in endothelial cells. Luciferase reporter assay showed that succinate increased VEGF expression through gene promoter activation dependent on HIF-1α induction. Intracellular succinate released into intercellular space, where extracellular succinate activated succinate receptor G-protein-coupled receptor 91 (GPR91) and induced VEGF production, further exacerbating angiogenesis. In addition, TGF-ß1 treatment increased succinate production due to the reversal of succinate dehydrogenase (SDH) activation, and consistently, SDH inhibitor dimethyl malonate reduced angiogenesis in the arthritis synovium. CONCLUSION AND IMPLICATIONS: More than an intermediate, succinate functioned as a signaling molecule to link metabolic reprograming with angiogenesis. Intracellular succinate induced angiogenesis through HIF-1α induction, while extracellular succinate acted on GPR91 activation, working together to disturb energy metabolism and exacerbate inflammation and angiogenesis in arthritis synovium. Our work suggested that suppression of SDH could prevent succinate accumulation and inhibit angiogenesis via blocking HIF-1α/VEGF axis. This finding not only provides a novel insight into angiogenesis, but also reveals a potential therapeutical strategy to attenuate revascularization in arthritis.

Comparison of three officinal species of Callicarpa based on a biochemome profiling strategy with UHPLC-IT-MS and chemometrics analysis.

Traditional Chinese medicine (TCM) materials with closely related species are frequently fungible in clinical use. Therefore, holistic comparison of the composition in bioactive compounds is essential to evaluate whether they are equivalent in efficacy. Taking three officinal species of Callicarpa as a case, we proposed and validated a standardized strategy for the discrimination of closely related TCM materials, which focused on the extraction, profiling and multivariate statistical analysis of their biochemome. Firstly, serial liquid-liquid extractions were utilized to prepare different batches of Callicarpa biochemome, and the preparation yields were utilized for the normalization of sampling quantity prior to UHPLC-IT-MS analysis. Secondly, 34 compounds, including 19 phenylethanoid glycosides, 10 flavonoids and 5 terpenoids, were identified based on an untargeted UHPLC-IT-MS method. Thirdly, method validation of linearity, precision and stability showed that the UHPLC-IT-MS system was qualified (R2>0.995, RSD<15%) for subsequent biochemome profiling. After PCA and PLS-DA analysis, 30 marker compounds were screened and demonstrated to be of good predictability using genetic algorithm optimized support vector machines. Finally, a heatmap visualization was employed for clarifying the distribution of marker compounds, which could be helpful to determine whether the three Callicarpa species are, in fact, equivalent substitutes. This study provides a standardized biochemome profiling strategy for systemic comparison analysis of closely related TCM materials, which shows promising perspectives in tracking the supply chain of pharmaceutical suppliers.