Astragaloside IV Modulates the Immune Response in Rheumatoid Arthritis and is Associated with Inhibition of the...

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by progressive joint destruction and systemic inflammation, with limited long-term efficacy and clinically important adverse effects of current treatments. Astragaloside IV (ASIV), the core active saponin component isolated from Astragalus membranaceus, has shown anti-inflammatory, immunomodulatory, and joint-protective potential in multiple inflammatory disease models, while its underlying mechanism in RA remains to be fully elucidated.

This study aimed to investigate whether ASIV alleviates RA by modulating the NAV2-Wnt/β-catenin signaling pathway.

A collagen-induced arthritis (CIA) model was established in female Wistar rats. The animals were randomly divided into four groups (n=6 per group initially, final n=3 per group based on modeling success criteria): healthy controls (NOR group), CIA model (CIA group), methotrexate-treated (MTX group, positive control, 0.9 mg/kg/week), and ASIV-treated (ASIV group, 50 mg/kg/day). Following a 4-week intervention period initiated on day 14 post-primary immunization, we evaluated arthritis severity (arthritis scores, vs volume), bone microstructure (micro-CT), histopathological features (H&E, Safranin O, Masson, TRAP staining), and serum levels of inflammatory cytokines (TNF-α, IL-1β, IL-6, IL-17A, IL-10, IL-13, detected by enzyme-linked immunosorbent assay (ELISA)) via abdominal aorta blood collection. Messenger RNA and protein expression levels of NAV2, Wnt3a, and β-catenin in the spleen and joint tissues were quantified using quantitative real-time polymerase chain reaction (qRT-PCR), Western blot, and immunohistochemistry (IHC). All data were analyzed using GraphPad Prism 8.3.0. Normality and homogeneity of variances were verified before analysis; one-way ANOVA followed by Tukey's post-hoc test was applied for multiple group comparisons, and independent t-test for pairwise comparisons. Statistical significance was set at P < 0.05.

Compared with the NOR group, rats in the CIA model group exhibited significant joint swelling, elevated arthritis scores, severe bone microstructure destruction, and disordered serum cytokine profiles, with increased pro-inflammatory factors (TNF-α, IL-1β, IL-6, IL-17A) and decreased anti-inflammatory factors (IL-10, IL-13) (P < 0.01). Meanwhile, the NAV2-Wnt/β-catenin signaling cascade was markedly activated at both mRNA and protein levels in the spleen and joint tissues of CIA rats (P < 0.001). Compared with the CIA group, ASIV treatment significantly alleviated arthritis severity, reduced joint swelling and bone erosion, normalized cytokine levels, and ameliorated histopathological damage (P < 0.01). The overall therapeutic efficacy of ASIV was comparable to that of the positive control MTX, with no statistically significant differences in most endpoints. Notably, ASIV significantly downregulated the mRNA and protein expression of NAV2, Wnt3a and β-catenin in both spleen and joint tissues (P < 0.01, P < 0.001), which was consistent with its ameliorative effects on inflammatory and structural injuries.

ASIV attenuated CIA-associated inflammatory and structural changes and was associated with reduced NAV2-Wnt/β-catenin pathway activation. These findings position the NAV2-Wnt/β-catenin cascade as a promising therapeutic target for ASIV in RA treatment, and support further development of ASIV as a potential natural-derived agent for RA management.