Photo-induced crosslinked and anti-PD-L1 peptide incorporated liposomes to promote PD-L1 multivalent binding for effective immune checkpoint blockade therapy

Immune checkpoint blockade(ICB)therapy targeting PD-L1 via monoclonal antibody(m Ab)has shown extensive clinical benefits in the diverse types of advanced malignancies.However,most patients are completely refractory to ICB therapy owing to the PD-L1 recycling mechanism.Herein,we propose photo-induced crosslinked and anti-PD-L1 peptide incorporated liposomes(immune checkpoint blockade liposomes;ICB-LPs)to promote PD-L1 multivalent binding for inducing lysosomal degradation of PD-L1 in tumor cells.The ICB-LPs are prepared by formulation of DC_(8,9)PC with photo-polymerized diacetylenic moiety,1,2-dipalmitoylphosphatidylcholine(DPPC)and anti-PD-L1peptide(D-form NYSKPTDRQYHF)-conjugated DSPE-PEG_(2k)(anti-PD-L1-DSPE-PEG_(2k))in a molar ratio of 45:45:10,followed by cross-linking of liposomal bilayer upon UV irradiation.The 10 mol% antiPD-L1-DSPE-PEG_(2k)incorporated ICB-LPs have a nano-sized lipid bilayer structure with an average diameter of 137.7±1.04 nm,showing a high stability in serum condition.Importantly,the ICB-LPs efficiently promote the multivalent binding with PD-L1 on the tumor cell membrane,which are endocytosed with aim to deliver PD-L1 to the lysosomes,wherein the durable PD-L1 degradation is observed for72 h,in contrast to anti PD-L1 m Abs showing the rapid PD-L1 recycling within 9 h.The in vitro coculture experiments with CD8^(+)T cells show that ICB-LPs effectively enhance the T cell-mediated antitumor immune responses against tumor cells by blocking the PD-L1/PD-1 axis.When ICB-LPs are intravenously injected into colon tumor-bearing mice,they efficiently accumulate within the targeted tumor tissues via both passive and active tumor targeting,inducing a potent T cell-mediated antitumor immune response by effective and durable PD-L1 degradation.Collectively,this study demonstrates the superior antitumor efficacy of crosslinked and anti-PD-L1 peptide incorporated liposome formulation that promotes PD-L1 multivalent binding for trafficking of PD-L1 toward the lysosomes instead of the recycling endosomes.

Spastin is required for human immunodeficiency virus-1 efficient replication through cooperation with the endosomal sorting complex required for transport(ESCRT)protein

Human immunodeficiency virus-1(HIV-1)encodes simply 15 proteins and thus depends on multiple host cellular factors for virus reproduction.Spastin,a microtubule severing protein,is an identified HIV-1 dependency factor,but the mechanism regulating HIV-1 is unclear.Here,the study showed that knockdown of spastin inhibited the production of the intracellular HIV-1 Gag protein and new virions through enhancing Gag lysosomal degradation.Further investigation showed that increased sodium tolerance 1(IST1),the subunit of endosomal sorting complex required for transport(ESCRT),could interact with the MIT domain of spastin to regulate the intracellular Gag production.In summary,spastin is required for HIV-1 replication,while spastin-IST1 interaction facilitates virus production by regulating HIV-1 Gag intracellular trafficking and degradation.Spastin may serve as new target for HIV-1 prophylactic and therapy.