Objectives: To determine whether any correlation exists between disease activity and AMPK levels in rheumatoid arthritis (RA) patients and investigate the effects of AMPK activator treatment on RA fibroblast-like synoviocytes (RA-FLS).Methods: Serum AMPK-α1, p-AMPK-α1, TNF-α and IL-17 levels between osteoarthritis (OA) and RA patients having different disease activities were compared by ELISA. Differentially expressed genes (DEGs) between RA and OA synovium from NCBI GEO Profiles (accession numbers: GSE1202112, GSE55235, GSE5545713) were identified and the genes intersecting in all the three datasets were selected for enrichment analysis. Immunohistochemical staining was done with synovium obtained from OA and RA patients for p-AMPK-α1. AMPK gene expression in synovium was semi-quantified by RT-qPCR. RNA sequencing of FLS was performed and DEGs were selected for KEGG enrichment analysis. AMPK activator, metformin, treated RA-FLS were tested for proliferation and migration by MTT and scratch test, respectively. Expression of IL-6, AMPK-α1, PKA-α, RAPTOR, mTOR, HAPLN1, RUNX1 and RUNX2 genes were determined by qPCR. Phosphorylated AMPK-α1 and HAPLN1 levels were determined by an automated electrophoresis-western blot analysis method.Results: In RA sera, a positive correlation between p-AMPK-α1 levels and DAS28 (r = 0.270, 95%CI: 0.142-0.492, p < 0.0001) as well as CRP levels (r = 0.259, 95%CI: 0.009-0.478, p < 0.05) was found. Similarly, a positive correlation was observed between AMPK-α1 and TNF-α levels (r = 0.460, 95% CI: 0.241-0.640, p = 0.0002). DEGs between OA and RA synovium from NCBI GEO profiles and our RNA sequencing data suggested activation of metabolic pathways specific to RA-FLS. AMPK-α1 was highly expressed in the synovium of RA but not OA patients. Metformin at higher concentrations inhibited RA-FLS proliferation in a dose dependant manner, however, at lower concentrations it has an opposite effect. On the other hand, AMPK inhibitor, dorsmophin, promoted the proliferation of RA-FLS significantly. Interestingly, both metformin and dorsmophin substantially inhibited the migration of RA-FLS. In FLS, relative expression level of IL-6 mRNA was significantly decreased after metformin treatment, while the expression of AMPK-α1, PKA-α and HAPLN1 genes were significantly increased. Western blot analysis confirmed increased expression of p-AMPK-α1 and HAPLN1 genes in the metformin treated FLS.Conclusions: Inflammatory stress in RA synovium leads to an increase in AMPK levels, possibly as a protective mechanism. AMPK activator but not metformin per se could be a potential therapeutic for RA by promoting HAPLN1 secretion to protect the joints.

Rheumatoid arthritis (RA) is a common autoimmune disease, and the inflammatory response during its development can lead to joint cartilage and bone damage up to disability. Dexamethasone (DEX) can effectively...

Background Elderly rheumatoid arthritis (ERA) population faces multiple treatment dilemma. Here we aim to investigate if Gancao Nourishing-Yin decoction (GCNY) added to methotrexate (MTX) exhibit better effects in an ERA mice model. Methods ERA mice model was established by adding D-galactose (Dgal) to collagen-induced arthritis (CIA) mice. The model was then assigned into control group (CIA + Dgal), MTX treatment group (MTX), GCNY treatment group (GCNY), and integrative treatment group (MTX + GCNY). Pathological scoring was performed to evaluate the severity between the groups. Proteomic analysis was applied to investigate the secretory phenotype of the ERA mouse model and the underlying mechanism of GCNY, MTX and their combination. Representative cytokines related to proteomic results were further validated by ELISAs. Results CIA + Dgal mice showed more aggressive joints damage than the CIA mice. Besides changes in the inflammatory pathway such as Pi3k-Akt signaling pathway in both model, differential expressed proteins (DEPs) indicated metabolism-related pathways were more obvious in CIA + Dgal mice. Low-dose MTX failed to show pathological improvement in CIA + Dgal mice, while GCNY improved joints damage significantly. Besides down-regulated inflammation-related targets, GCNY-regulated DEPs (such as Apoc1 ~ 3, Grk2 and Creb3l3) were broadly enriched in metabolism-related pathways. MTX + GCNY showed the best therapeutic effect, and the DEPs enriched in a variety of inflammatory,metabolism and osteoclast differentiation signaling pathway. Notably, MTX + GCNY treatment up-regulated Dhfr, Cbr1, Shmt1 involved in folic acid biosynthesis and anti-folate resistance pathways indicated a coincidence synergic action. ELISAs confirmed CPR and Akt that elevated in CIA + Dgal mice were significantly ameliorated by treatments, and adding on GCNY elevated folic acid levels and its regulator Dhfr. Conclusion Aging aggravated joints damage in CIA, which probably due to metabolic changes rather than more severe inflammation. GCNY showed significant effects in the ERA mice model especially when integrated with MTX to obtain a synergic action.