MSC Exosomes and Rutin-Chitosan-Pectin Nanoparticles Synergize to Ameliorate Adjuvant Arthritis via Th1/Th2 Modulation, MMP Suppression, Nrf2 Upregulation, and Antioxidant Boost.

Background: Due to toxicity, high costs, and potential side effects of standard treatments of rheumatoid arthritis (RA) including nonsteroidal anti-inflammatory drugs (NSAIDs), corticosteroids, and disease-modifying antirheumatic drugs (DMARDs), natural products and advanced drug delivery systems, such as nanoparticles and mesenchymal stem cell (MSC)-derived exosomes (EXO), have garnered interest due to their ability to target inflammation and oxidative damage, with enhanced precision and reduced side effects, offering a promising approach for RA management. Methods: EXO were isolated from the conditioned medium of bone marrow-derived MSCs (BM-MSCs). Rutin (RT)-loaded chitosan (Cs)/pectin nanoparticles were prepared using a modified ionic gelation technique to enhance stability and bioavailability. Sixty male Wistar rats were utilized in the in vivo experiment and randomly assigned to six groups, each comprising 10 animals. These groups were (1) normal control, (2) complete Freund's adjuvant (CFA)-induced arthritic control, (3) CFA-induced arthritis treated with free RT (20 mg/kg), (4) CFA-induced arthritis treated with EXO (100 µg protein per rat, intravenous injection, once weekly), (5) CFA-induced arthritis treated with RT-Cs-pectin nanocomposite (RT-CPN) (20 mg/kg), and (6) CFA-induced arthritis treated with a combination of RT-CPN and EXO. Treatments were administered for 28 days, after which the rats were euthanized for further analysis. For molecular evaluations, blood was collected for serum isolation, and the right ankle joint was carefully dissected. Results: Treatment with RT, EXO, RT-CPN, and especially, EXO + RT-CPN combination significantly reduced serum levels of anticitrullinated protein antibodies (ACPAs), interleukin-1β (IL-1β), interleukin-6 (IL-6), and the marker of oxidative stress malondialdehyde (MDA). These treatments also decreased inducible nitric oxide synthase (iNOS) mRNA expression, a key regulator of oxidative and inflammatory processes. Conversely, antioxidant defenses improved, as indicated by increased serum glutathione (GSH), interleukin-10 (IL-10), and interleukin-13 (IL-13) levels, along with upregulation of antioxidant enzymes such glutathione peroxidase (GPx), glutathione S-transferase (GST), glutathione reductase (GR), and superoxide dismutase (SOD). Joint degradation was notably reduced by suppressing the protein levels of MMP-1, MMP-3, MMP-9, and MMP-13, while nuclear factor erythroid 2-related factor 2 (Nrf2) expression, a critical regulator of cellular protection, was elevated. Along with improvements in functional and molecular markers, the right hind leg's swelling and redness decreased, and the histological alterations including pannus development, inflammatory cell infiltrations, synovial membrane hyperplasia, and degradation of articular cartilage were substantially suppressed after treatments. Conclusions: The combination of EXO + RT-CPN demonstrated the strongest antiarthritic effects, reducing inflammation, oxidative stress, and joint degradation while boosting the body's antioxidant defenses. These findings highlight a promising, safer therapeutic strategy for RA management.