Spatiotemporally targeted nanocapsules combined with mild photothermal therapy regulate the synovial microenvironment in rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic autoimmune disease characterized by persistent synovial inflammation and progressive joint destruction. Its pathogenesis involves aberrant activation and aggressive proliferation of fibroblast-like synoviocytes (FLS), excessive macrophage infiltration, and disrupted M1/M2 macrophage polarization within the synovial microenvironment (SME). However, current therapies remain inadequate for precise SME modulation, often leading to limited efficacy and poor prognosis. To address this challenge, we developed a multifunctional nanocapsule, termed RP/HP@Mn/L, which is composed of a low molecular weight heparin (LMWH)-modified, Mn²⁺-doped hollow mesoporous polydopamine (HP) nanocarrier co-loaded with rapamycin (Rap) and paeoniflorin (Pae). This nanocapsule's dual-ligand strategy targets P-selectin on inflamed endothelial cells and integrin αM on inflammatory macrophages, enabling precise spatiotemporal accumulation at the pathological site. This nanocapsule enables spatiotemporally specific targeting of both inflammatory endothelial cells and inflammatory macrophages, thereby enhancing precise drug delivery to pathological sites. Mechanistic investigations revealed that RP/HP@Mn/L, in combination with mild photothermal therapy (PTT) mediated by HP, effectively suppressed FLS proliferation and invasion. Concurrently, it promoted the polarization of macrophages from the pro-inflammatory M1 to the anti-inflammatory M2 phenotype. These synergistic effects facilitated the remodeling of the SME, thereby alleviating synovitis and enhancing bone repair in RA. In conclusion, this study proposes a spatiotemporally targeted combinatorial nanotherapeutic strategy that integrates multimodal mechanisms for SME modulation. This approach represents a promising therapeutic platform for improving outcomes in RA and other autoimmune disorders.