M2-like Polarization Research Articles

Local Spinal Cord Injury Treatment Using a Dental Pulp Stem Cell Encapsulated H2S Releasing Multifunctional Injectable Hydrogel.

Spinal cord injury (SCI) commonly induces nerve damage and nerve cell degeneration. In this work, a novel dental pulp stem cells (DPSCs) encapsulated thermoresponsive injectable hydrogel with sustained hydrogen sulfide (H2S) delivery is demonstrated for SCI repair. For controlled and sustained H2S gas therapy, a clinically tested H2S donor (JK) loaded octysilane functionalized mesoporous silica nanoparticles (OMSNs) are incorporated into the thermosensitive hydrogel made from Pluronic F127 (PF-127). The JK-loaded functionalized MSNs (OMSF@JK) promote preferential M2-like polarization of macrophages and neuronal differentiation of DPSCs in vitro. OMSF@JK incorporated PF-127 injectable hydrogel (PF-OMSF@JK) has a soft consistency similar to that of the human spinal cord and thus, shows a high cytocompatibility with DPSCs. The cross-sectional micromorphology of the hydrogel shows a continuous porous structure. Last, the PF-OMSF@JK composite hydrogel considerably improves the in vivo SCI regeneration in Sprague-Dawley rats through a reduction in inflammation and neuronal differentiation of the incorporated stem cells as confirmed using western blotting and immunohistochemistry. The highly encouraging in vivo results prove that this novel design on hydrogel is a promising therapy for SCI regeneration with the potential for clinical translation.

The inhibition effect of caffeic acid on NOX/ROS-dependent macrophages M1-like polarization contributes to relieve the LPS-induced mice mastitis

The mammary gland is an adipose tissue containing not only adipocytes but also epithelial, endothelial, and immune cells. Epithelial cells and macrophages, as the integral components of the immune system, are on the front line of defense against infection. Our preliminary work proved that caffeic acid (CA) can effectively inhibit the inflammatory cascade of bovine mammary epithelial cells (BMEC) induced by lipopolysaccharide (LPS) and maintain cellular integrity and viability. Here, we investigated the therapeutic effect of CA on LPS-induced mice mastitis and explored its regulatory mechanism on macrophage inflammatory response induced by LPS in vitro. Firstly, the mice mastitis model was established by intramammary injection with 10 μg LPS, after which different CA doses (5, 10, 15 mg/kg) were administered. Then, the pathological section, myeloperoxidase (MPO) activity, proinflammatory factors and chemokines releasement, and redox state of mammary tissues were assessed, confirming CA's effectiveness on mice mastitis. In vitro, we validated the therapeutic relevance of CA in relieving LPS-induced RAW264.7 inflammatory and oxidative stress responses. Moreover, we further provided evidence that CA significantly reduced LPS-induced reactive oxygen species (ROS) generation via NADPH oxidase (NOX), which improved the imbalance relationship between nuclear factor kappa-B (NF-κB) and NF-E2 p45-related factor 2 (Nrf2) and led to a marked weakening of M1 polarization. The NOX-ROS signal inhibited by CA weakened the oxidative burst and neutrophil chemotaxis of macrophages, thus alleviating the immune cascade in mammary gland tissue and reducing the LPS-induced inflammatory damage. Collectively, CA would be a potential candidate or antibacterial synergist for curbing mastitis.

Noncytotoxic Carbon Nanotubes Bioconjugated with Fucosyltransferase 4-Derived Peptides Modulate Macrophage Polarization In Vitro

Important developments in nanoparticle-based therapies have occurred in recent years. Carbon nanotubes (CNTs) are among the most valuable nanoparticles because of their physicochemical properties and functionalization possibilities; therefore, they are proposed as peptide carriers for immunotherapy. Immunotherapy has been explored as a promising treatment for ovarian cancer (OvCa), and it has been reported that macrophage polarization to M1 and M2 phenotypes plays a pivotal role in OvCa initiation, progression, and metastasis, providing therapeutic targets for macrophage-targeted treatment. In this work, we explored the initial stages of designing CNT-based immunotherapy for OvCa using fucosyltransferase-4-derived T-cell epitopes conjugated with CNTs (f-CNTs). Their cytotoxicity and biological interactions were analyzed in macrophages (J774A.1) and human ovarian cancer cells (SKOV-3). Here, f-CNTs did not show cytotoxicity at concentrations < 6 μg/mL; additionally, they induced morphological changes and activation in macrophages; time-dependent uptake in lysosomes; production of M1-like cytokines; upregulation of CD80, CD86, and major histocompatibility complex II (MHC II); and downregulation of arginase-1 (ARG-1). In conclusion, f-CNTs exhibited biocompatibility in both cell lines and displayed M1-like polarization in macrophages, and we propose their exploration as a peptide carrier system for macrophage activation and polarization in ovarian cancer immunotherapy.

CD133-containing microvesicles promote cancer progression by inducing M2-like tumor-associated macrophage polarization in the tumor microenvironment of colorectal cancer.

Tumor-associated macrophages (TAMs) are among the most abundant cell types in the tumor microenvironment (TME). The immunosuppressive TME formed by TAMs is an essential prerequisite for cancer progression. Tumor-derived microvesicles (MVs), a subtype of extracellular vesicle shed directly from the plasma membrane, are important regulators of intercellular communication and TME modulation during tumorigenesis. However, the exact mechanism by which tumor-derived MVs induce the generation of the immunosuppressive TME and polarization of TAMs remains unclear. Here, we investigated the role of CD133-containing MVs derived from colorectal cancer (CRC) cells in macrophage polarization and cancer progression. CD133-containing MVs from CRC cells were incorporated into macrophages, and M0 macrophages were morphologically transformed into M2-like TAMs. CD133-containing MVs were found to increase the mRNA expression of M2 macrophage markers. Additionally, cytokine array analysis revealed that M2-like TAMs induced by CD133-containing MVs increased the secretion of interleukin 6, which activated the STAT3 pathway in CRC cells. Furthermore, the conditioned medium of M2-like TAMs promoted cell motility, epithelial-mesenchymal transition, and cell proliferation. However, MVs from CD133-knockdown cells had little effect on TAM polarization and CRC progression. These results demonstrate that CD133-containing MVs induce M2-like TAM polarization and contribute to cancer progression by mediating crosstalk between tumor cells and TAMs in the TME of CRC.

Medrysone promotes corneal injury repair by promoting M2-like polarization of macrophages

BackgroundAccumulated evidence suggests that M2-like polarized macrophages plays an important role in reducing inflammation, promoting and accelerating wound healing process and tissue repair. Thus, M2-like TAMs (Tumour-associated macrophages) was an appealing target for therapy intervention.MethodFlow cytometry and RT-PCR assay were used to detect the polarization of macrophages induced by Medrysone, and the rat corneal mechanical injury model was established to evaluate the efficacy of Medrysone in cornel repair.ResultsHere we found that Medrysone enhanced IL-4 induced M2 polarization of macrophages, as illustrated by increased expression of CD206, up-regulation of M2 marker mRNAs. Medrysone promoted VEGF and CCL2 secretion in IL-4 induced M2-like polarization. IL-4 triggered STAT6 activation was further enhanced by Medrysone and silencing of STAT6 partially abrogated the stimulatory effect of Medrysone. Medrysone improved migration-promoting feature of M2-like macrophages, as indicated by increased migration of endothelial cells. Further, Medrysone promoted corneal injury repair by inducing M2 polarization of macrophages in vivo.ConclusionOur study suggest that Medrysone promotes corneal injury repair by inducing the M2 polarization of macrophages, providing a theoretical basis for the application of Medrysone in the treatment of corneal injury.

Second-Generation M1-Like CAR Macrophages Exhibit Antitumor Activity

Abstract Second-generation CAR macrophages exhibit sustained M1-like polarization and antitumor activity.

Kv1.3 Blockade Alleviates White Matter Injury through Reshaping M1/M2 Phenotypes via the NF-κB Signaling Pathway after Intracerebral Hemorrhage.

White matter injury (WMI) in basal ganglia usually induces long-term disability post intracerebral hemorrhage (ICH). Kv1.3 is an ion channel expressed in microglia and induces neuroinflammation after ICH. Here, we investigated the functions and roles of Kv1.3 activation-induced inflammatory response in WMI and the Kv1.3 blockade effect on microglia polarization after ICH. Mice ICH model was constructed by autologous blood injection. The expression of Kv1.3 was measured using immunoblot, real-time quantitative polymerase chain reaction (RT-qPCR), and immunostaining assays. Then, the effect of administration of 5-(4-Phenoxybutoxy) psoralen (PAP-1), a selectively pharmacological Kv1.3 blocker, was investigated using open field test (OFT) and basso mouse score (BMS). RT-qPCR, immunoblot, and enzyme-linked immunosorbent assay (ELISA) were taken to elucidate the expression of pro-inflammatory or anti-inflammatory factors around hematoma. PAP-1's function in regulating microglia polarization was investigated using immunoblot, RT-qPCR, and immunostaining assays. The downstream PAP-1 signaling pathway was determined by RT-qPCR and immunoblot. Kv1.3 expression was increased in microglia around the hematoma significantly after ICH. PAP-1 markedly improved neurological outcomes and the WMI by reducing pro-inflammatory cytokine accumulation and upregulating anti-inflammatory factors. Mechanistically, PAP-1 reduces NF-κB p65 and p50 activation, thus facilitating microglia polarization into M2-like microglia, which exerts this beneficial effect. PAP-1 reduced pro-inflammatory cytokines accumulation and increased anti-inflammatory factors by facilitating M2-like microglia polarization via the NF-κB signaling pathway. Thus, the current study shows that the Kv1.3 blockade is capable of ameliorating WMI by facilitating M2-like phenotype microglia polarization after ICH.

Biofunctional Inorganic Layered Double Hydroxide Nanohybrid Enhances Immunotherapeutic Effect on Atopic Dermatitis Treatment.

Atopic dermatitis (AD) is a widespread, recurrent, and chronic inflammatory skin condition that imposes a major burden on patients. Conventional treatments, such as corticosteroids, are associated with various side effects, underscoring the need for innovative therapeutic approaches. In this study, the possibility of using indole-3-acetic acid-loaded layered double hydroxides (IAA-LDHs) is evaluated as a novel treatment for AD. IAA is an auxin-class plant hormone with antioxidant and anti-inflammatory effects. Following the synthesis of IAA-LDH nanohybrids, their ability to induce M2-like macrophage polarization in macrophages obtained from mouse bone marrow is assessed. The antioxidant activity of IAA-LDH is quantified by assessing the decrease in intracellular reactive oxygen species levels. The anti-inflammatory and anti-atopic characteristics of IAA-LDH are evaluated in a mouse model of AD by examining the cutaneous tissues, immunological organs, and cells. The findings suggest that IAA-LDH has great therapeutic potential as a candidate for AD treatment based on its in vitro and in vivo modulation of AD immunology, enhancement of macrophage polarization, and antioxidant activity. This inorganic drug delivery technology represents a promising new avenue for the development of safe and effective AD treatments.

Hypoxic tumour-derived exosomal miR-1225-5p regulates M2 macrophage polarisation via toll-like receptor 2 to promote ovarian cancer progress

Tumor-secreted exosomes are critical for the functional regulation of tumor-associated macrophages (TAMs). This study aimed to explore how exosomes secreted by ovarian carcinoma cells regulate the phenotype and function of macrophages. Hypoxic treatment of A2780 cells was postulated to mimic the tumor microenvironment, and exosomes were co-cultured with TAMs. miR-1225-5p was enriched in hypoxic exosomes and contributed to M2 macrophage polarizationby modulating Toll-like receptor 2 expression (TLR2). Furthermore, hypoxia-treated macrophages promote ovarian cancer cell viability, migration, and invasion via the wnt/β-catenin pathway. This study clarified that exosomal miR-1225-5p promotes macrophage M2-like polarization by targeting TLR2 to promote ovarian cancer, which may via the wnt/β-catenin pathway.

Meloxicam treatment disrupts the regional structure of innate inflammation sites by targeting the pro-inflammatory effects of prostanoids.

Non-steroidal anti-inflammatory drugs (NSAIDs) are the most widely prescribed drugs in the world due to their analgesic, antipyretic and anti-inflammatory effects. However, NSAIDs inhibit prostanoid synthesis, interfering with their pro-inflammatory and anti-inflammatory functions and potentially prolonging acute inflammation. We used high-content immunohistochemistry to define the impact of meloxicam treatment on spatially separated pro-inflammatory and anti-inflammatory processes during innate inflammation in mice induced by zymosan. This allowed us to determine the effect of meloxicam treatment on the organization of pro-inflammatory and anti-inflammatory microenvironments, thereby identifying relevant changes in immune cell localization, recruitment and activation. Meloxicam treatment reduced zymosan-induced thermal hypersensitivity at early time points but delayed its resolution. High-content immunohistochemistry revealed that the pro-inflammatory area was smaller after treatment, diminishing neutrophil recruitment, M1-like macrophage polarization, and especially phagocytosis by neutrophils and macrophages. The polarization of macrophages towards the M2-like anti-inflammatory phenotype was unaffected, and the number of anti-inflammatory eosinophils actually increased. High-content immunohistochemistry was able to identify relevant meloxicam-mediated effects on inflammatory processes based on alterations in the regional structure of inflammation sites. Meloxicam delayed the clearance of pathogens by inhibiting pro-inflammatory processes, causing prolonged inflammation. Our data suggest that the prescription of NSAIDs as a treatment during an acute pathogen-driven inflammation should be reconsidered in patients with compromised immune systems.

SEPTIN2 suppresses an IFN-γ-independent, proinflammatory macrophage activation pathway

Interferon-gamma (IFN-γ) signaling is necessary for the proinflammatory activation of macrophages but IFN-γ-independent pathways, for which the initiating stimuli and downstream mechanisms are lesser known, also contribute. Here we identify, by high-content screening, SEPTIN2 (SEPT2) as a negative regulation of IFN-γ-independent macrophage autoactivation. Mechanistically, endoplasmic reticulum (ER) stress induces the expression of SEPT2, which balances the competition between acetylation and ubiquitination of heat shock protein 5 at position Lysine 327, thereby alleviating ER stress and constraining M1-like polarization and proinflammatory cytokine release. Disruption of this negative feedback regulation leads to the accumulation of unfolded proteins, resulting in accelerated M1-like polarization, excessive inflammation and tissue damage. Our study thus uncovers an IFN-γ-independent macrophage proinflammatory autoactivation pathway and suggests that SEPT2 may play a role in the prevention or resolution of inflammation during infection.

Oxoaporphine Pr(III) complex inhibits hepatocellular carcinoma progression and metastasis by disrupting tumor cell–macrophage crosstalk

Tumor cells and macrophages communicate through the secretion of various cytokines to jointly promote the malignant development of cancers. We synthesized and characterized an oxoaporphine Pr(III) complex (PrL3(NO3)3) and found that it inhibits hepatocellular carcinoma (HCC) progression and metastasis by disrupting HCC cell–macrophage crosstalk. PrL3(NO3)3 treatment upregulated CD86, TNF-α, and IL-1β and downregulated CD163, CD206, CCL2, and VEGFA in macrophages. Our mRNA-Seq results demonstrated that PrL3(NO3)3 inhibited macrophage M2-like polarization by inhibiting the AMPK pathway and activating the NF-κB pathway by upregulating RelA/p65 Ser536 phosphorylation. This kind of macrophage polarization significantly inhibited HCC cell proliferation, migration, and invasion. In addition, PrL3(NO3)3 inhibited the migration, invasion, and chemotaxis of HCC cells by downregulating the expression of EMT-related markers and CCL2. hTFtarget database analysis revealed that PrL3(NO3)3 inhibited NF-κB nuclear translocation by upregulating RelA/p65 Ser536 phosphorylation in HCC cells, thereby downregulating the expression of Snail and CCL2. HCC tissue microarray analysis revealed that downregulation of RelA/p65 Ser536 phosphorylation is a driving event in HCC malignant progression. In conclusion, PrL3(NO3)3 effectively inhibits HCC cell–macrophage crosstalk by upregulating RelA/p65 Ser536 phosphorylation. This is the first report of a lanthanide complex exerting regulatory effects on both tumors and tumor-associated macrophages, providing a new strategy for the development of effective antitumor drugs.

Tumor-derived microparticles promoted M2-like macrophages polarization to stimulate osteosarcoma progression

Microparticles (MPs) are a heterogeneous subpopulation of extracellular vesicles that originate from the plasma membranes of cells. There is increasing evidence that tumor-derived MPs (T-MPs) play a significant role in tumor progression and immune response in cancer. In our study, we found an increased secretion of MPs in osteosarcoma tissues obtained from metastatic patients. These T-MPs promoted polarization of M2-like macrophages and stimulated the migration and chemoresistance of osteosarcoma cells. Mechanistically, T-MPs promoted macrophage polarization to an M2-like phenotype through TBK1-STAT6 signaling. Consequently, these M2-like macrophages mediated osteosarcoma cell migration via CCL18/STAT3 signaling. Blockade of STAT3 signaling pathway improved the outcome of chemotherapy in LM8-bearing osteosarcoma mice model. Thus, our study reveals how tumor cells regulate macrophage polarization by releasing MPs and provides new insights into clinical osteosarcoma therapy.

CNSC-06. REDIRECTING IMMUNOSUPPRESSIVE GLIOMA MICROENVIRONMENT THROUGH PHARMACOLOGICAL INTERVENTION TARGETING NEURONAL ACTIVITY

Abstract Recent single-cell RNA-sequencing analyses have revealed a strong association between glioma-neuronal circuit remodeling and regional immunosuppression. Subsequent preclinical investigations using syngeneic tumor models demonstrated that genetic disruption of circuit assembly genes, including Thrombospondin-1 (TSP-1/Thbs1) in GBM cells suppressed synaptogenesis, excitatory neurotransmitter ligand and receptor density in addition to neuronal activities while simultaneously restoring inflammatory responses, indicating glioma-neuron-immune cross talk. However, the underlying mechanisms and directions of causality remain unclear. Here we test the hypothesis that tumor-derived synaptogenic factors directly reprogram the tumor immune microenvironment (“model 1”). Alternatively, tumor intrinsic neuronal activity may indirectly regulate adaptive immunity (“model 2”). In this study, we performed in-vitro bone-marrow-derived macrophage (BMDM) reprogramming assays evaluating various stimulation conditions and in-vivo experiments evaluating the effect of neuronal activity-oriented therapy on the tumor-associated macrophages (TAMs). Our in-vitro assays demonstrated that, secreted factors from mouse neonatal cortical neurons (not tumor-derived synaptogenic factors) induced an anti-inflammatory, M2-like phenotype of BMDMs, corroborating the proposed model 2. This M2-inducing effect was inhibited when the neuronal activities were suppressed pharmacologically, using perampanel (PER), a noncompetitive inhibitor of neuronal AMPA-type glutamate receptors. Direct treatment of BMDMs with PER did not affect the polarization patterns, further supporting the M2-inducing effect of glutamatergic excitatory neuronal signals. In in-vivo syngeneic orthotopic tumor models, treatment with PER significantly prolonged survival compared to the non-treated group (27.5 [PER] vs. 23 days [control], p = 0.01). Flow cytometric analysis of brain-infiltrating leukocytes showed that TAMs isolated from PER-treated mice exhibited a more proinflammatory M1-like polarization compared to the control group (median M1/M2 ratio, 1.2 [PER] vs. 0.7 [control], p = 0.004), which explained the improved prognosis. Collectively, these findings unveil novel immunosuppression mechanisms induced by glioma-neuronal circuit remodeling and the resulting excitatory neuronal signals, and potential therapeutic vulnerabilities that could be targeted in combination with cancer immunotherapy.

TMIC-17. THE ROLE OF ICAM1 IN GLIOBLASTOMA TUMORIGENESIS UNDER HYPOXIC CONDITIONS

Abstract Glioblastoma (GBM) is a deadly brain cancer in adults with limited treatment options. Cell adhesion molecules (CAMs) mediate cell-cell interactions and migration. Intercellular adhesion molecule 1 (ICAM-1) is a CAM expressed by various cell types in solid tumors, including macrophages, tumor and endothelial cells. We previously demonstrated that ICAM-1 expression is linked to shorter overall survival in GBM patients. We observed elevated ICAM-1 levels in hypoxic regions of GBMs. Considering the role of tumor-associated macrophages (TAMs) in GBM tumorigenicity, our objective was to investigate how ICAM-1 expression in TAMs contributes to GBM growth within the hypoxic tumor microenvironment (TME). We employed a comprehensive approach utilizing in vitro and in vivo models, as well as genomic analyses at both bulk and single-cell levels, to elucidate the association between ICAM-1 and TAMs in tumorigenicity. Our findings demonstrated that injecting GBM cells into ICAM-1 knockout mice led to prolonged survival, smaller tumors, reduced macrophage infiltration, and enhanced M1-like polarization of TAMs. Additionally, bone marrow reconstitution experiments confirmed the tumor-promoting role of ICAM-1-expressing TAMs. Cell deconvolution, immunohistochemical, and flow cytometry analyses of mouse tumors supported these findings. Gene set enrichment analysis of differentially expressed genes in xenografted tumors revealed that ICAM-1 presence upregulated key tumorigenic pathways, including epithelial-mesenchymal transition, IL2-STAT5, TNF-α via NFκB, IL6-JAK-STAT3, and RAS/MAPK. In vitro analysis indicated that ICAM-1 promoted macrophage migration and polarization towards M2-like state, which was further augmented by hypoxia-induced ICAM1 expression. Flow cytometry, cytometry by time of flight (cyToF), and single-cell RNA sequencing analysis of human and mouse GBMs revealed elevated ICAM-1 expression in hypoxic TAMs, suggesting the hypoxic microenvironment promotes the tumorigenic functions of TAMs. In conclusion, ICAM1 likely enhances GBM tumorigenesis by promoting TAM migration into the TME. Furthermore, environmental factors such as hypoxia contribute to increased ICAM-1 expression in TAMs, further exacerbating GBM tumorigenicity.

Aortic valve calcification is promoted by clonal hematopoiesis associated with DNMT3A and TET2 gene driver mutations

Abstract Background Clonal hematopoiesis (CH) due to DNMT3A or TET2-driver mutations is associated with coronary heart disease and worse prognosis among patients with aortic valve stenosis (AVS) and inflammation. However, it is unknown what role CH plays in the pathogenesis of AVS. AVS is the most common age-related heart valve disease, with no medical therapy to halt progression. Methods and Results Single-cell RNA-sequencing of immune cells of CAVD patients (n=13) with and without the most prevalent CH-mutations (DNMT3A and TET2), with mean CH-driver gene variant allele frequency was 6.5% for DNMT3A and 17.9% for TET2. Monocytes of patients harboring DNMT3A and TET2 mutations shared 836 upregulated genes, many associated with glycolytic, pro-inflammatory activation (CXCL10, IL38) and paracrine pro-calcific factors (oncostatin M (OSM), S100A9), suggesting that CH might be causally involved in AVS. Indeed, silencing of TET2 or DNMT3A in macrophages promotes M1-like polarization and increases release of pro-calcific mediators, particularly S100A9 and OSM. To assess whether CH-gene silenced macrophages may stimulate mesenchymal cells to secrete calcium, secreted factors from TET2 or DNMT3A-silenced macrophages were applied mesenchymal cells. Indeed, CH-gene silenced secretomes induced osteoblastic differentiation of mesenchymal cells, evidenced by increased Alizarin red calcium staining and elevated levels of ALP and RUNX2. This CH-mediated enhancement in osteoblastic conversion could be ablated by silencing of OSM. Finally, valves from atheroprone Ldlr-/- mice receiving TET2-/- bone marrow transplants demonstrated increased total calcified area (1.49-fold) along with increased numbers of calcification deposits (2.33-fold) as evidenced by von Kossa staining, along with enhanced OSM and S100A9 levels. Conclusion This is the first study to demonstrate that somatic CH-driver mutations in monocytes may accelerate AVS. Moreover, calcification was ablated via silencing of OSM in CH-gene silenced macrophages. These data suggest Oncostatin M may be a therapeutically promising target in halting the progression of AVS in patients harboring CH mutations.

Abstract 15477: Mitochondrial Drp1 Deficiency in Macrophage Limits Revascularization of Ischemic Muscle via Inflammatory Metabolic Reprograming and Macrophage Polarization

Background: In preclinical peripheral artery disease (PAD) models, M2-like anti-inflammatory macrophage polarization, arteriogenesis and angiogenesis are crucial in restoring perfusion recovery and revascularization. Mitochondrial dynamics in macrophage regulates cell metabolism and inflammation. Mitochondrial fission protein, Drp1 GTPase is shown to be involved in pro- or anti-inflammatory macrophage phenotypes in a context-dependent manner. However, role of macrophage Drp1 in reparative neovascularization in experimental PAD model remains unknown. Method and Results: Macrophage-specific Drp1 knockout (MФ-Drp1-KO; LysCre x Drp1 fl/fl) or wild type (WT) mice were used for hindlimb ischemia (HLI), a preclinical PAD model. Drp1 expression was dramatically increased in F4/80 + macrophage in ischemic muscle at day 3 after HLI of WT mice. MФ-Drp1-KO mice showed decreased limb perfusion (78.3%), angiogenesis (53.0 %), arteriogenesis (46.3%), and muscle regeneration (41.9%) after HLI. This was associated with increased pro-inflammatory M1-like MФ (2.2 fold by FACS analysis), p-NFkB and TNFα expression and decreased anti-inflammatory M2-like MФ (2.3 fold by FACS analysis) and p-AMPK in ischemic muscle of MФ-Drp1-KO mice vs. WT mice. In vitro, bone marrow-derived MФ with hypoxia serum starvation (HSS) (in vitro PAD model) induced mitochondrial fission and activated Drp1. Drp1 KO MФ under HSS exhibited increased glycolysis (66.7%, ECAR) via reduced p-AMPK as well as excess mitochondrial (mito)ROS production (2 fold), which in turn increased M1-genes ( Nos2 and Ptgs2 ) and decreased M2-genes ( Arg1 and Retnla ). These responses in Drp1 KO MФ were rescued by AMPK activator AICAR and mitoROS scavenger mitoTEMPO. Finally, conditioned media from HSS-treated Drp1 KO MФ showed increased secretion of pro-inflammatory TNFα and GAPDH and suppressed angiogenic responses of cultured endothelial cells (50%). Conclusion: Drp1 dysfunction in macrophage promotes inflammatory macrophage polarization induced by hyperglycolysis via suppression of anti-inflammatory AMPK as well as excess mitoROS, which limits revascularization in experimental PAD.

Multifunctional Ca2+ nanomodulators regulate type I interferon pathway to remodel tumor microenvironment for cancer immunotherapy

Although immune checkpoint blockade (ICB) therapy has been widely used for the treatment of a variety of cancers, its therapeutic efficacy is severely impaired by low tumor immunogenicity and the immunosuppressive microenvironment. Herein, we designed multifunctional immunomodulatory calcium nanoparticles to reshape the immunosuppressive tumor microenvironment. Our multifunctional calcium nanoparticles, CD@CaCO3P, are designed to release calcium ions and doxorubicin (DOX) into the acidic tumor microenvironment, which synergistically increase the tumor cell calcium ion concentration, while the release of combretastatin A4 phosphate (CA4P) further enhances T cell infiltration. Specifically, CD@CaCO3P effectively mediates the immunogenic cell death (ICD) of tumor cells and triggers the activation of nuclear factor kappa-B (NF-κB)/interferon regulatory factor 3 (IRF3), thereby regulating type I interferon (IFN-I) signaling pathways, and ultimately reprogramming the immunosuppressive tumor microenvironment by inducing M1-like macrophage polarization, promoting dendritic cell maturation, and increasing the infiltration of CD8+ T cells. Furthermore, CD@CaCO3P significantly increased tumor susceptibility to α-PD-1 checkpoint blocking immunotherapy and enhanced systemic immunotherapy performance against both primary and metastatic tumors. Our work provides new insights for the use functional calcium nanoparticles that modulate the tumor microenvironment to enhance the efficacy of cancer immunotherapy.

Cucurbitacin I Reverses Tumor-Associated Macrophage Polarization to Affect Cancer Cell Metastasis.

The tumor microenvironment plays a critical role in tumor progression and immune regulation. As one of the most important components of the tumor microenvironment, macrophages have become a new therapeutic target for inhibiting tumor progression. Despite the well-documented anticancer activity of cucurbitacin I, its effect on macrophages remains unclear. In this study, we established a coculture system of macrophages and cancer cells under hypoxic conditions to simulate the tumor-promoting environment mediated by M2-like macrophages. We determined whether cucurbitacin I modulates M2-like polarization in macrophages in vitro and conducted RNA sequencing to identify gene expression changes induced by cucurbitacin I in macrophages. The results indicated a remarkable inhibition of the M2-like polarization phenotype in macrophages following treatment with cucurbitacin I, which was accompanied by the significant downregulation of heme oxygenase-1. Moreover, we found that cucurbitacin I-treated macrophages reduced the migration of cancer cells by inhibiting the M2 polarization in vitro. These findings highlight the potential of cucurbitacin I as a therapeutic agent that targets M2-like macrophages to inhibit cancer cell metastasis. Our study provides novel insights into the intricate interplay among macrophage polarization, cucurbitacin I, and heme oxygenase-1, thereby opening new avenues for cancer treatment.

HBV suppresses macrophage immune responses by impairing the TCA cycle through the induction of CS/PDHC hyperacetylation.

It is now understood that HBV can induce innate and adaptive immune response disorders by affecting immunosuppressive macrophages, resulting in chronic HBV infection. However, the underlying mechanism is not fully understood. Dysregulated protein acetylation can reportedly influence the differentiation and functions of innate immune cells by coordinating metabolic signaling. This study aims to assess whether HBV suppresses macrophage-mediated innate immune responses by affecting protein acetylation and to elucidate the underlying mechanisms of HBV immune escape. We investigated the effect of HBV on the acetylation levels of human THP-1 macrophages and identified potential targets of acetylation that play a role in glucose metabolism. Metabolic and immune phenotypes of macrophages were analyzed using metabolomic and flow cytometry techniques. Western blot, immunoprecipitation, and immunofluorescence were performed to measure the interactions between deacetylase and acetylated targets. Chronic HBV persistent infected mice were established to evaluate the role of activating the tricarboxylic acid (TCA) cycle in macrophages for HBV clearance. Citrate synthase/pyruvate dehydrogenase complex hyperacetylation in macrophages after HBV stimulation inhibited their enzymatic activities and was associated with impaired TCA cycle and M2-like polarization. HBV downregulated Sirtuin 3 (SIRT3) expression in macrophages by means of the toll-like receptor 2 (TLR2)-NF-κB- peroxisome proliferatoractivated receptor γ coactivator 1α (PGC-1α) axis, resulting in citrate synthase/pyruvate dehydrogenase complex hyperacetylation. In vivo administration of the TCA cycle agonist dichloroacetate inhibited macrophage M2-like polarization and effectively reduced the number of serum HBV DNA copies. HBV-induced citrate synthase/pyruvate dehydrogenase complex hyperacetylation negatively modulates the innate immune response by impairing the TCA cycle of macrophages. This mechanism represents a potential therapeutic target for controlling HBV infection.