"Y-type” PEG modified liposomes could eliminate the accelerated blood clearance (ABC) phenomenon and improved tumor therapy

Poly(ethylene glycol) (PEG) is widely applied to decorate nanocarriers due to its "long circulation” characteristics. However, the applications of linear PEG-modified nanocarriers have been hindered by severe adverse effects due to the accelerated blood clearance (ABC) phenomenon. It was universally known that anti-PEG antibodies (APAs) were main culprits in ABC phenomenon which induced the significant change in pharmacokinetics, biological distributions of the second injection and triggered complement activation-related pseudoallergies (CARPA). Recent studies have illustrated that APAs triggered the ABC phenomenon of PEGylated protein drug and even related to the CARPA of COVID-19 vaccine. Therefore, it is urgent to inhibit the generation of APAs and eliminate the ABC phenomenon. Here, "Y-type” PEG was chosen to replace linear PEG due to its weak immunogenicity. "Y-type” PEG-lipid derivatives [DSPE-mPEG2,n (n = 2, 10, and 20 kDa)]-modified doxorubicin liposomes (DOX-PL2,n) and topotecan liposomes (TP-PL2,n) induced lower levels of APAs and could avoid activating complement system. In further research, we found that liposomes decorated with DSPE-mPEG2,n could avoid the ABC phenomenon after duplicate injections. Furthermore, pharmacodynamic tests indicated that DOX-PL2,n and TP-PL2,n improved the curative effect of S180 tumor than DOX-PL2k and TP-PL2k (linear PEGylated liposomes). For the first time, DOX-PL2,n and TP-PL2,n were used for in vivo pharmacokinetic and pharmacodynamic experiments. Liposomes ornamented with "Y-type” PEG may provide new approaches to maintaining long blood circulation time, eliminating the ABC phenomenon of encapsulated active compounds, and also could weaken CARPA and improve tumor therapeutic effect. Our research aims to promote the research and development of "Y-type” PEG-decorated nanocarriers and provide a substantial academic basis for its clinical application.

Minimalist Nanocomplex with Dual Regulation of Endothelial Function and Inflammation for Targeted Therapy of Inflammatory Vascular Diseases.

Vascular disorders, characterized by vascular endothelial dysfunction combined with inflammation, are correlated with numerous fatal diseases, such as coronavirus disease-19 and atherosclerosis. Achieving vascular normalization is an urgent problem that must be solved when treating inflammatory vascular diseases. Inspired by the vascular regulatory versatility of nitric oxide (NO) produced by endothelial nitric oxide synthase (eNOS) catalyzing l-arginine (l-Arg), the eNOS-activating effects of l-Arg, and the powerful anti-inflammatory and eNOS-replenishing effects of budesonide (BUD), we constructed a bi-prodrug minimalist nanoplatform co-loaded with BUD and l-Arg via polysialic acid (PSA) to form BUD-l-Arg@PSA. This promoted vascular normalization by simultaneously regulating vascular endothelial dysfunction and inflammation. Mediated by the special affinity between PSA and E-selectin, which is highly expressed on the surface of activated endothelial cells (ECs), BUD-l-Arg@PSA selectively accumulated in activated ECs, targeted eNOS expression and activation, and promoted NO production. Consequently, the binary synergistic regulation of the NO/eNOS signaling pathway occurred and improved vascular endothelial function. NO-induced nuclear factor-kappa B alpha inhibitor (IκBα) stabilization and BUD-induced nuclear factor-kappa B (NF-κB) response gene site occupancy achieved dual-site blockade of the NF-κB signaling pathway, thereby reducing the inflammatory response and inhibiting the infiltration of inflammation-related immune cells. In a renal ischemia-reperfusion injury mouse model, BUD-l-Arg@PSA reduced acute injury. In an atherosclerosis mouse model, BUD-l-Arg@PSA decreased atherosclerotic plaque burden and improved vasodilation. This represents a revolutionary therapeutic strategy for inflammatory vascular diseases.

Sialic acid-conjugate modified doxorubicin nanoplatform for treating neutrophil-related inflammation.

Neutrophils, the most abundant leukocytes in human peripheral blood, are important effector cells that mediate the inflammatory response. During neutrophil dysfunction, excessive activation and uncontrolled infiltration are the core processes in the progression of inflammation-related diseases, including severe coronavirus disease-19 (COVID-19), sepsis, etc. Herein, we used sialic acid-modified liposomal doxorubicin (DOX-SAL) to selectively target inflammatory neutrophils in the peripheral blood and deliver DOX intracellularly, inducing neutrophil apoptosis, blocking neutrophil migration, and inhibiting the inflammatory response. Strong selectivity resulted from the specific affinity between SA and L-selectin, which is highly expressed on inflammatory neutrophil membranes. In inflammation models of acute lung inflammation/injury (ALI), sepsis, and rheumatoid arthritis (RA), DOX-SAL suppressed the inflammatory response, increased the survival of mice, and delayed disease progression, respectively. Moreover, DOX-SAL restored immune homeostasis in the body, without side effects. We have presented a targeted nanocarrier drug delivery system that can block the recruitment of inflammatory neutrophils, enabling specific inhibition of the core disease process and the potential to treat multiple diseases with a single drug. This represents a revolutionary treatment strategy for inflammatory diseases caused by inappropriate neutrophil activation.