Cationic micelle delivery of a multi-epitope vaccine candidate derived from tumor-associated antigens, causing regression in established CT26 colorectal tumors in mice

Among all the cancers, colorectal cancer (CRC) has the third mortality rank in both genders. Cancer vaccines have shown promising results in boosting patients' immune systems to fight cancer. Using the IEDB database, we predicted mouse MHC-I (H2-Ld) binding epitopes from four tumor-associated antigens (APC, KRAS, TP53, and PIK3CA) and designed a multi-epitope vaccine. We expressed the candidate vaccine and encapsulated it into the cationic micelle with polyethyleneimine conjugated to oleic acid as its building blocks. We studied tumor inhibition effect, cytokine production, and lymphocyte proliferation in the mouse CRC model after vaccination. Our finding illustrated significant tumor growth inhibition in mouse models treated with the candidate nanovaccine. Besides the significant release of IFN-γ and IL-4 by immunized mouse spleen T-lymphocytes, T-cell proliferation assay results confirmed effective immune response after the vaccination. These results demonstrate the potential therapeutic effects of nanovaccines and could be a possible approach to CRC immunotherapy.

Selective Antimicrobial Activities and Action Mechanism of Micelles Self-Assembled by Cationic Oligomeric Surfactants

This work reports that cationic micelles formed by cationic trimeric, tetrameric, and hexameric surfactants bearing amide moieties in spacers can efficiently kill Gram-negative E. coli with a very low minimum inhibitory concentration (1.70-0.93 μM), and do not cause obvious toxicity to mammalian cells at the concentrations used. With the increase of the oligomerization degree, the antibacterial activity of the oligomeric surfactants increases, i.e., hexameric surfactant > tetrameric surfactant > trimeric surfactant. Isothermal titration microcalorimetry, scanning electron microscopy, and zeta potential results reveal that the cationic micelles interact with the cell membrane of E. coli through two processes. First, the integrity of outer membrane of E. coli is disrupted by the electrostatic interaction of the cationic ammonium groups of the surfactants with anionic groups of E. coli, resulting in loss of the barrier function of the outer membrane. The inner membrane then is disintegrated by the hydrophobic interaction of the surfactant hydrocarbon chains with the hydrophobic domains of the inner membrane, leading to the cytoplast leakage. The formation of micelles of these cationic oligomeric surfactants at very low concentration enables more efficient interaction with bacterial cell membrane, which endows the oligomeric surfactants with high antibacterial activity.