Internalization and membrane activity of the antimicrobial peptide CGA-N12.

Antimicrobial peptides (AMPs) are conventional antibiotic alternatives due to their broad-spectrum antimicrobial activities and special mechanisms of action against pathogens. The antifungal peptide CGA-N12 was originally derived from human chromogranin A (CGA) and consists of the 65th to 76th amino acids of the CGA N-terminal region. In the present study, we found that CGA-N12 had fungicidal activity and exhibited time-dependent inhibition activity against Candida tropicalis. CGA-N12 entered the cells to exert its antagonist activity. The internalization of CGA-N12 was energy-dependent and accompanied by actin cytoskeleton-, clathrin-, sulfate proteoglycan-, endosome-, and lipid-depleting agent-mediated endocytosis. Moreover, the CGA-N12 internalization pathway was related to the peptide concentration. The effects of CGA-N12 on the cell membrane were investigated. CGA-N12 at a low concentration less than 4 × MIC100 did not destroy the cell membrane. While with increasing concentration, the damage to the cell membrane caused by CGA-N12 became more serious. At concentrations greater than 4 × MIC100, CGA-N12 destroyed the cell membrane integrity. Therefore, the membrane activity of CGA-N12 is concentration dependant.

Ultrasound-Activatable In Situ Vaccine for Enhanced Antigen Self- and Cross-Presentation to Overcome Cancer Immunotherapy Resistance.

Insufficient antigen self-presentation of tumor cells and ineffective antigen cross-presentation by dendritic cells (DCs) contribute to diminished immune recognition and activation, which cause resistance to immunotherapies. Herein, we present an ultrasound-activatable in situ vaccine by utilizing a hybrid nanovesicle composed of a thylakoid (TK)/platelet (PLT) membrane and a liposome encapsulating DNA methyltransferase inhibitor zebularine (Zeb) and sonosensitizer hematoporphyrin monomethyl ether (HMME). Upon local exposure to ultrasound, reactive oxygen species (ROS) are generated and induce the sequential release of the payloads. Zeb can efficiently inhibit tumor DNA hypermethylation, promoting major histocompatibility complex class I (MHC-I) molecules-mediated antigen self-presentation to improve immune recognition. Meanwhile, the catalase on the TK membrane can decompose the tumoral overexpressed H2O2 into O2, which boosts the generation of ROS and the destruction of tumor cells, resulting in the in situ antigen release and cross-presentation of tumor antigens by DCs. This in situ vaccine simultaneously promotes antigen self-presentation and cross-presentation, resulting in heightened antitumor immunity to overcome resistance.

A Dual-Mechanism Based Nutrient Partitioning Nanoregulator for Enhanced Immunotherapy against Anti-PD-1 Resistant Tumors.

Competitive consumption of nutrients between rapidly proliferating cancer cells and T cells results in an immunosuppressive tumor microenvironment (TME) and nutrient deprivation of T cells, which can cause low response rate and resistance to immunotherapies. In this study, we proposed a dual-mechanism based nutrient partitioning nanoregulator (designated as DMNPN), which can simultaneously regulate the immunosuppressive TME and enhance T cell nutrient availability. DMNPN consists of a charge-reversal biodegradable mesoporous silica, encapsulating glycolysis inhibitor lonidamine, and small interfering RNA against glutaminase. Through inhibiting glycolysis to decrease the lactic acid production and downregulating glutaminase expression to reduce the uptake of glutamine by tumor cells, DMNPN enables effective remodeling of metabolism and nutrient partitioning, which alleviates the immunosuppressive TME and boosts nutrient availability for T cells with enhanced antitumor immunity. Such a nutrient partitioning nanoregulator can effectively inhibit the growth of anti-programmed death receptor 1 (anti-PD-1) resistant tumors and prevent tumor metastasis and recurrence. Overall, this dual-mechanism based nutrient reallocation strategy provides a promising approach for cancer therapy.