[Cell membrane-coated nanoparticles in disease therapy].

Nanotechnology has attracted increasing attention in the field of medical applications due to its significant potential for development. However, one major challenge that has emerged with nanoparticles is their tendency to activate the host immune clearance system, which hampers the achievement of desired therapeutic outcomes and may lead to harmful side effects. In recent years, membrane-coated nanoparticles have emerged as a promising solution, demonstrating their effectiveness in evading immune system clearance. These innovative nanoparticles inherit essential biological attributes from natural cell membranes, such as anchoring proteins and antigens. Consequently, membrane-coated nanoparticles exhibit unique capabilities such as immune evasion, prolonged circulation, targeted drug release, and immune modulation, substantially enhancing their versatility and prospects within the realm of biomedical applications. This review provides a comprehensive overview of the current applications of cell membrane-coated nanoparticles in disease therapy, highlighting their immense potential in this rapidly evolving platform. Additionally, the review outlines the promising prospects of this technology in disease therapy.

Systematic evaluation of membrane-camouflaged nanoparticles in neutralizing Clostridium perfringens ε-toxin.

Clostridium perfringens ε-toxin (ETX) is the main toxin leading to enterotoxemia of sheep and goats and is classified as a potential biological weapon. In addition, no effective treatment drug is currently available in clinical practice for this toxin. We developed membrane-camouflaged nanoparticles (MNPs) with different membrane origins to neutralize ETX and protect the host from fatal ETX intoxication. We evaluated the safety and therapeutic efficacy of these MNPs in vitro and in vivo. Compared with membranes from karyocytes, such as Madin-Darby canine kidney (MDCK) cells and mouse neuroblastoma N2a cells (N2a cells), membrane from erythrocytes, which do not induce any immune response, are superior in safety. The protective ability of MNPs was evaluated by intravenous injection and lung delivery. We demonstrate that nebulized inhalation is as safe as intravenous injection and that both modalities can effectively protect mice against ETX. In particular, pulmonary delivery of nanoparticles more effectively treated the challenge of inhaled toxins than intravenously injected nanoparticles. Moreover, MNPs can alter the biological distribution of ETX among different organs in the body, and ETX was captured, neutralized and slowly delivered to the liver and spleen, where nanoparticles with ETX could be phagocytized and metabolized. This demonstrates how MNPs treat toxin infections in vivo. Finally, we injected the MNPs into mice in advance to find out whether MNPs can provide preventive protection, and the results showed that the long-cycle MNPs could provide at least a 3-day protection in mice. These findings demonstrate that MNPs provide safe and effective protection against ETX intoxication, provide new insights into membrane choices and delivery routes of nanoparticles, and new evidence of the ability of nanoparticles to provide preventive protection against infections.

Clostridium perfringens epsilon toxin binds to erythrocyte MAL receptors and triggers phosphatidylserine exposure.

Epsilon toxin (ETX) is a 33-kDa pore-forming toxin produced by type B and D strains of Clostridium perfringens. We previously found that ETX caused haemolysis of human red blood cells, but not of erythrocytes from other species. The cellular and molecular mechanisms of ETX-mediated haemolysis are not well understood. Here, we investigated the effects of ETX on erythrocyte volume and the role of the putative myelin and lymphocyte (MAL) receptors in ETX-mediated haemolysis. We observed that ETX initially decreased erythrocyte size, followed by a gradual increase in volume until lysis. Moreover, ETX triggered phosphatidylserine (PS) exposure and enhanced ceramide abundance in erythrocytes. Cell shrinkage, PS exposure and enhanced ceramide abundance were preceded by increases in intracellular Ca2+ concentration. Interestingly, lentivirus-mediated RNA interference studies in the human erythroleukaemia cell line (HEL) cells confirmed that MAL contributes to ETX-induced cytotoxicity. Additionally, ETX was shown to bind to MAL in vitro. The results of this study recommend that ETX-mediated haemolysis is associated with MAL receptor activation in human erythrocytes. These data imply that interventions affecting local MAL-mediated autocrine and paracrine signalling may prevent ETX-mediated erythrocyte damage.

Immunization with a novel Clostridium perfringens epsilon toxin mutant rETX(Y196E)-C confers strong protection in mice.

Epsilon toxin (ETX) is produced by toxinotypes B and D of Clostridium perfringens. It can induce lethal enterotoxemia in domestic animals, mainly in sheep, goats and cattle, causing serious economic losses to global animal husbandry. In this study, a novel and stable epsilon toxin mutant rETX(Y196E)-C, obtained by substituting the 196th tyrosine (Y196) with glutamic acid (E) and introducing of 23 amino acids long C-terminal peptide, was determined as a promising recombinant vaccine candidate against enterotoxemia. After the third vaccination, the antibody titers against recombinant wild type (rETX) could reach 1:10(5) in each immunized group, and the mice were completely protected from 100 × LD50 (50% lethal dose) of rETX challenge. The mice in 15 µg subcutaneously immunized group fully survived at the dose of 500 × LD50 of rETX challenge and 80% of mice survived at 180 µg (1000 × LD50) of rETX administration. In vitro, immune sera from 15 µg subcutaneously immunized group could completely protect MDCK cells from 16 × CT50 (50% lethal dose of cells) of rETX challenge and protect against 10 × LD50 dose (1.8 µg) of rETX challenge in mice. These data suggest that recombinant protein rETX(Y196E)-C is a potential vaccine candidate for future applied researches.

Development of aequorin-based mast cell nanosensor for rapid identification of botulinum neurotoxin type B.

An aequorin-based mast cell sensor was developed for rapid identification and detection of protein toxins. To monitor mast cell activation and to improve the sensitivity of detection, aequorin was stably expressed in the cells and used as an indicator of calcium flux and the stable cell line was created. The procedures for preparing cells were optimized to improve the quantum yield and sensitivity of detection. The cells sensitized with anti-DNP (dinitrophenyl) IgE were capable of detecting as little as 0.1 ng/mL DNP-BSA in less than 2 min. To demonstrate the utility of this mast cell sensor in detecting protein toxins, an IgE chimeric protein (p21-Fcε) was created. This was achieved by fusing the Fc region of IgE antibody to a 21-amino acid peptide (p21) derived from residues 40-60 of synaptotagmin II (Syt II), the protein receptor of botulinum neurotoxin type B (BoNT/B). In addition, magnetic beads linked with anti-BoNT/B polyclonal antibody were prepared to capture BoNT/B molecules in solution to make targets multivalent and concentrated. The p21-Fcε binds to FcsRI receptors on RBL (Rat basophilic leukemia) cells and can be cross-linked by BoNT/B captured by the magnetic beads. This led to cell activation and Ca2+ flux indicated by an increase of quantum yield. This assay can detect as little as 100 pM (15 ng/mL) BoNT/B in less than 1 hr, which included the initial sample preparation time. This study lays a foundation for detecting other protein toxins using mast cell sensors.