Celastrol-loaded bovine serum albumin nanoparticles target inflamed neutrophils for improved rheumatoid arthritis therapy.

Inflammatory neutrophils (INEs), motivated by cytokines, continue to migrate into the inflamed joints, driving the development of RA. Hence, inducing apoptosis of INEs to reduce recruitment at inflamed joints is an effective strategy for the treatment of RA. However, simply apoptotic INEs may trigger the release of neutrophil extracellular traps (NETs) and accelerate the inflammatory process. To overcome these drawbacks, an RGD-modified bovine serum albumin (BSA) nanoparticles (CBR NPs) was fabricated to selectively target INEs in situ for intracellular delivery of CLT. Studies have demonstrated that CBR NPs can selectively target circulating INEs and induce INEs apoptosis. Meanwhile, CBR NPs inhibited the activation of NETs via NF-κB pathway and the release of Cit-H3 thereby blocking the release process of NETs. In collagen-induced arthritis (CIA) mouse model, CBR NPs suppressed the inflammatory response, and reduced the toxic effects of CLT. In summary, this study shed light on an innovative approach to treat RA by inducing apoptosis of circulating INEs and inhibiting NETs. STATEMENT OF SIGNIFICANCE: RGD-modified bovine serum albumin (BSA) nanoparticles for delivering celastrol, abbreviated as CBR NPs, were constructed to inhibit the infiltration of circulating inflammatory neutrophils (INEs) into inflamed joints while inhibiting the release of NETs to alleviate tissue damage. CBR NPs were prepared for the first time to induce apoptosis of INEs; CBR NPs could inhibit the release of NETs while inducing apoptosis of INEs in vivo and vitro cellular experiments; CBR NPs had favorable anti-inflammatory effects and low toxicity side-effects in collagen-induced arthritis (CIA) mouse models. The application of nanotechnology to induce apoptosis of INEs while inhibiting the release of NETs was a promising approach for the treatment of RA.