Immunomodulatory Microparticles Epigenetically Modulate T Cells and Systemically Ameliorate Autoimmune Arthritis

Area of Science:

• Immunology
• Rheumatology
• Drug Delivery Systems

Background:

• Conventional disease-modifying antirheumatic drugs (DMARDs) show limited efficacy in a significant portion of patients with autoimmune inflammatory arthritides.
• There is a need for novel therapeutic strategies that can effectively manage autoimmune arthritis while minimizing systemic side effects.

Purpose of the Study:

• To investigate the potential of sustained, joint-localized release of all-trans retinoic acid (ATRA) using biodegradable microparticles as a disease-modifying treatment for autoimmune arthritis.
• To elucidate the immunoregulatory mechanisms underlying ATRA's therapeutic effects in the context of arthritis.

Main Methods:

• Development and intra-articular (IA) injection of poly-(lactic-co-glycolic) acid (PLGA)-based biodegradable microparticles encapsulating ATRA (PLGA-ATRA MP) in mouse models of autoimmune arthritis.
• Assessment of T cell differentiation, regulatory T cell (Treg) populations, joint inflammation, and structural damage (proteoglycan loss, bone erosions).
• Evaluation of systemic immune effects and disease modification in both injected and uninjected joints.

Main Results:

• IA PLGA-ATRA MP administration led to sustained joint-localized ATRA release, enhancing anti-inflammatory regulatory T cells (Tregs).
• This approach effectively reduced joint inflammation, proteoglycan loss, and bone erosions in SKG and collagen-induced arthritis mouse models.
• Therapeutic effects were observed in both injected and uninjected joints, mimicking the effects of IA Treg injection, without causing generalized immune suppression.

Conclusions:

• Sustained intra-articular delivery of ATRA via PLGA microparticles represents a promising immunoregulatory strategy for autoimmune arthritis.
• This localized approach modulates immune responses to protect joints and control systemic disease, offering a potential alternative to conventional DMARDs.
• PLGA-ATRA MP demonstrate potential for development as a targeted disease-modifying agent for autoimmune arthritis.