Intracellular Magnetic Hyperthermia Enables Concurrent Down-Regulation of CD47 and SIRPα To Potentiate Antitumor Immunity.

Harnessing the potential of tumor-associated macrophages (TAMs) to engulf tumor cells offers promising avenues for cancer therapy. Targeting phagocytosis checkpoints, particularly the CD47-signal regulatory protein α (SIRPα) axis, is crucial for modulating TAM activity. However, single checkpoint inhibition has shown a limited efficacy. In this study, we demonstrate that ferrimagnetic vortex-domain iron oxide (FVIO) nanoring-mediated magnetic hyperthermia effectively suppresses the expression of CD47 protein on Hepa1-6 tumor cells and SIRPα receptor on macrophages, which disrupts CD47-SIRPα interaction. FVIO-mediated magnetic hyperthermia also induces immunogenic cell death and polarizes TAMs toward M1 phenotype. These changes collectively bolster the phagocytic ability of macrophages to eliminate tumor cells. Furthermore, FVIO-mediated magnetic hyperthermia concurrently escalates cytotoxic T lymphocyte levels and diminishes regulatory T cell levels. Our findings reveal that magnetic hyperthermia offers a novel approach for dual down-regulation of CD47 and SIRPα, reshaping the tumor microenvironment to stimulate immune responses, culminating in significant antitumor activity.

A polyoxyethylene sorbitan oleate modified hollow gold nanoparticle system to escape macrophage phagocytosis designed for triple combination lung cancer therapy via LDL-R mediated endocytosis.

Presently, a combination of chemotherapy, radiotherapy, thermotherapy, and other treatments has become a hot topic of research for the treatment of cancer, especially lung cancer. In this study, novel hollow gold nanoparticles (HGNPs) were used as drug carriers, and in order to improve the targeting ability of HGNPs to a lung tumor site, polyoxyethylene sorbitol oleate (PSO) was chosen here as a target ligand since it can be specifically recognized by the low-density lipoprotein (LDL) receptor which is usually over expressed on A549 lung cancer cells. In this way, a PSO-modified doxorubicin-loaded HGNP drug delivery system (PSO-HGNPs-DOX) was constructed and its physicochemical properties, photothermal conversion ability, and drug release of PSO-HGNPs-DOX was investigated. Further, the effects of triple combination therapy, the intracellular uptake, and the ability to escape macrophage phagocytosis of PSO-HGNPs-DOX were also studied using A549 cells in vitro. In addition, an in vivo mouse model was also used to study the targeting of PSO-HGNPs-DOX to lung cancer. PSO-HGNPs-DOX demonstrated a good triple therapeutic effect for lung cancer (A549 cell viability was only 10% at 500 µM) by LDL receptor mediated endocytosis and was able to escape macrophage phagocytosis to enhance its accumulation at the target site. Therefore, PSO-HGNPs-DOX is a novel, safe, promising, and targeted drug carrier designed for triple combination lung cancer therapy which should be further studied for such applications.

Micronized, Heat-Treated Lactobacillus plantarum LM1004 Alleviates Cyclophosphamide-Induced Immune Suppression.

The present study investigated the immunomodulatory activity and associated mechanisms of heat-treated Lactobacillus plantarum LM1004 (HT-LM1004) in a cyclophosphamide (CTX)-induced mouse model of immunosuppression. HT-LM1004 induced phagocytic activity and nitric oxide production in RAW264.7 macrophages and stimulated the release of tumor necrosis factor (TNF)-α, interferon (IFN)-γ, interleukin (IL)-2, and IL-12p70. In mice with CTX-induced immunosuppression, oral HT-LM1004 administration restored thymus and spleen indices, including spleen weight. Consistent with the in vitro results, HT-LM1004 increased TNF-α, IFN-γ, IL-2, and IL-12p70 levels in mice after 14 days of treatment and enhanced the natural killer (NK) cell activity of splenocytes from mice with CTX-induced immunosuppression against YAC-1 lymphoma cells. The method of HT-LM1004 generation influenced this activity: L. plantarum LM1004 grown in a membrane bioreactor, which reduced the size of the cells to <1.0 µm through physical stress (micronization), promoted NK cell cytotoxicity to a greater extent than LM1004 subjected to heat treatment alone. These findings indicate that HT-LM1004 without or with micronization can reverse CTX-induced immunosuppression without adverse side effects by potentiating NK cell function.

Casticin Promotes Immune Responses, Enhances Macrophage and NK Cell Activities, and Increases Survival Rates of Leukemia BALB/c Mice.

Casticin, derived from Fructus Viticis, has anticancer properties in many human cancer cells, however, there is no report to show that casticin promotes immune responses and affects the survival rate of leukemia mice in vivo. The aim of this study is to evaluate the effects of casticin on immune responses and the survival rate of WEHI-3 cells generated in leukemia mice in vivo. Animals were divided into six groups: normal control mice, leukemia control mice, mice treated with ATRA (all-trans retinoic acid), and casticin (0.1, 0.2, and 0.4 mg/kg) treated mice. All animals were treated for 14 days and then measured for body weights, total survival rate, cell markers, the weights of liver and spleen, phagocytosis of spleen cells, NK cell activities and cell proliferation. Results show that casticin did not affect animal appearances, however, it increased body weights and decreased the weights of liver at 0.2 mg/kg and 0.4 mg/kg treatment. Casticin also decreased spleen weight at 0.2 mg/kg and 0.4 mg/kg treatment, increased CD3 at 0.1, 0.2 and 0.4 mg/kg doses and increased CD19 at 0.2 mg/kg treatment but decreased CD11b and Mac-3 at 0.1, 0.2 and 0.4 mg/kg treatment. Casticin (0.1, 0.2 and 0.4 mg/kg) increased macrophage phagocytosis from PBMC (peripheral blood mononuclear cell) and peritoneal cavity. Furthermore, casticin increased NK cells' cytotoxic activity and promoted T cell proliferation at 0.1-0.4 mg/kg treatment with or without concanavalin A (Con A) stimulation, but only increased B cell proliferation at 0.1 mg/kg treatment. Based on these observations, casticin could be used as promoted immune responses in leukemia mice in vivo.

Photo-enhancement of macrophage phagocytic activity via Rac1-mediated signaling pathway: Implications for bacterial infection.

Phagocytosis and the subsequent destruction of invading pathogens by macrophages are indispensable steps in host immune responses to microbial infections. Low-power laser irradiation (LPLI) has been found to exert photobiological effects on immune responses, but the signaling mechanisms underlying this photobiomodulation of phagocytosis remains largely unknown. Here, we demonstrated for the first time that LPLI enhanced the phagocytic activity of macrophages by stimulating the activation of Rac1. The overexpression of constitutively activated Rac1 clearly enhanced LPLI-induced phagocytosis, whereas the overexpression of dominant negative Rac1 exerted the opposite effect. The phosphorylation of cofilin was involved in the effects of LPLI on phagocytosis, which was regulated by the membrane translocation and activation of Rac1. Furthermore, the photoactivation of Rac1 was dependent on the Src/PI3K/Vav1 pathway. The inhibition of the Src/PI3K pathway significantly suppressed LPLI-induced actin polymerization and phagocytosis enhancement. Additionally, LPLI-treated mice exhibited increased survival and a decreased organ bacterial load when challenged with Listeria monocytogenes, indicating that LPLI enhanced macrophage phagocytosis in vivo. These findings highlight the important roles of the Src/PI3K/Vav1/Rac1/cofilin pathway in regulating macrophage phagocytosis and provide a potential strategy for treating phagocytic deficiency via LPLI.