PLA₂-Triggered Release of Drugs from Self-Assembled Lipid Tubules for Arthritis Treatments

Environment-responsive drug delivery is a promising approach for tailoring the drug release in drug therapy. In this study, we develop lipid tubules by the self-assembly of 1,2-bis(tricosa-10,12-diynoyl)-sn-glycero-3-phosphocholine (DC_8,9PC). These lipid tubules are capable of encapsulating hydrophobic dexamethasone (Dex) and hydrophilic dexamethasone sodium phosphate (DSP) simultaneously. In vitro studies show that the lipid tubules can be internalized by cells with no significant toxicity. We find that phospholipase (PLA₂) is able to slowly digest the lipid tubules and trigger the sustained release of Dex and DSP. After being subcutaneously administrated to the inflammatory sites of arthritic rats, we show that a single dose of drug-loaded lipid tubules can remarkably inhibit the degree of joint swelling at the inflammatory sites and suppress the content of proinflammatory cytokines in inflamed tissues for a long time by this sustained release of both Dex and DSP triggered by the highly expressed PLA₂ at the inflamed sites. Our results highlight the potential of using PLA₂-responsive lipid tubules as on-demand carriers for treating inflammatory diseases.