Enhanced Therapeutic Effect of RGD-Modified Polymeric Micelles Loaded With Low-Dose Methotrexate and Nimesulide on Rheumatoid Arthritis.

Angiogenesis plays an essential role in the progression of rheumatoid arthritis (RA). RGD peptide shows high affinity and selectivity for integrin αβ which is one of the most extensively examined target of angiogenesis. Nimesulide could improve the anti-rheumatic profile of methotrexate. But the clinical application was limited due to water-insolubility of both methotrexate and nimesulide and lacking targeting ability. Therefore, this study aimed to design a targeted drug delivery system of micelles mediated by RGD plus the passive targeting of micelles to solve the application problems of methotrexate and nimesulide (M/N), and thus enhance their combined therapeutic effect on RA. RGD was conjugated with NHS-PEG-PLA to form RGD-PEG-PLA for the preparation of RGD-modified drug-loaded micelles (R-M/N-PMs). The size and zeta potential of micelles were measured by dynamic light scattering. Morphology was detected by transmission electron microscopy. The inhibition effect of R-M/N-PMs on angiogenesis was assessed by the chick chorioallantoic membrane assay. The real-time fluorescence imaging analysis was conducted to examine the distribution of the fluorescence-labeled R-M/N-PMs. Rats arthritis model induced by Freund's adjuvant was used to evaluate the anti-inflammatory efficacy of R-M/N-PMs. The study indicated successful development of R-M/N-PMs. R-M/N-PMs could markedly suppress the angiogenesis of chick embryos. The fluorescence-labeled R-M/N-PMs mainly accumulated in arthritic joints. RGD enhanced the targeting ability of micelles and thus promoted retention of micelles in arthritic joints. Moreover, R-M/N-PMs significantly alleviated the joint swelling while reducing bone erosion and serum levels of inflammatory cytokines. It helped to recover the bone microstructure of arthritic rats. Our results confirmed that the targeted delivery of the combination of a low dose of methotrexate and nimesulide mediated by RGD-modified polymeric micelles could enhance the therapeutic effect on rheumatoid arthritis. These findings provide a promising potential for the clinical therapy of rheumatoid arthritis.