Metabolomics combined with network pharmacology to study the mechanism of Shentong Zhuyu decoction in the treatment of rheumatoid arthritis

Shentong Zhuyu decoction (STZYD) was first recorded in the classic of "Yilin Gaicuo" written by Wang Qingren, and recognized by the Chinese National Administration of Traditional Chinese Medicine as one of the 100 classic formulas. The formula has been widely used in the treatment of rheumatoid arthritis (RA) with significant clinical effects. However, its mechanism of action is not completely clear.This study aimed to explore the mechanism of STZYD in the treatment of RA by network pharmacology and metabolomics.The effects of STZYD anti-RA were investigated by paw swelling, arthritis score, cytokine level, histopathological and micro-CT analysis in adjuvant-induced arthritis (AIA) rats. The chemical constituents of STZYD and absorbed constituents in AIA rat serum were analyzed by UPLC-Q-Exactive MS/MS. Based on the characterized chemical components, the network pharmacology was used to find potential targets and signaling pathways of STZYD in RA treatment. Meanwhile, the predicted pathway was determined by the Western blot (WB). Subsequently, non-targeted metabolomics of serum was performed to analyze metabolic profiles, potential biomarkers, and metabolic pathways of STZYD in the treatment of RA based on LC-MS technology.STZYD significantly alleviated RA symptoms by improving paw redness and swelling, bone and cartilage damage, synovial hyperplasia, and infiltration of inflammatory cells, and decreased the generation of pro-inflammatory cytokines IL-1β, IL-6, IL-17A and TNF-α in AIA rats. Totally, 59 chemical components of STZYD and 24 serum migrant ingredients were identified. A total of 655 genes of potential bioactive components in STZYD and 1025 related genes of RA were obtained. TNF signaling pathway was considered to one of the main signaling pathways of STZYD anti-RA by KEGG analysis, including a wide range intracellular signaling pathways. NF-κB signaling pathway regulates inflammation and immunity in the TNF signaling pathway. STZYD markedly inhibited the expression of NF-κB signaling pathway. Ten potential biomarkers were found in metabolomics based on LC-MS technology. Alanine, aspartate and glutamate metabolism, arachidonic acid metabolism are the most related pathways of STZYD anti-RA.The study based on serum pharmacochemistry, network pharmacology and metabolomics indicated that STZYD can improve RA through regulating inflammation and immunity related pathways, and provided a new possibility for treatment of RA.