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Current Oncology (Toronto, Ont.) Jun 2024Neuroblastoma is a pediatric cancer with significant clinical heterogeneity. Despite extensive efforts, it is still difficult to cure children with high-risk... (Review)
Review
Neuroblastoma is a pediatric cancer with significant clinical heterogeneity. Despite extensive efforts, it is still difficult to cure children with high-risk neuroblastoma. Immunotherapy is a promising approach to treat children with this devastating disease. We have previously reported that macrophages are important effector cells in high-risk neuroblastoma. In this perspective article, we discuss the potential function of the macrophage inhibitory receptor SIRPA in the homeostasis of tumor-associated macrophages in high-risk neuroblastoma. The ligand of SIRPA is CD47, known as a "don't eat me" signal, which is highly expressed on cancer cells compared to normal cells. CD47 is expressed on both tumor and stroma cells, whereas SIRPA expression is restricted to macrophages in high-risk neuroblastoma tissues. Notably, high expression is associated with better disease outcome. According to the current paradigm, the interaction between CD47 on tumor cells and SIRPA on macrophages leads to the inhibition of tumor phagocytosis. However, data from recent clinical trials have called into question the use of anti-CD47 antibodies for the treatment of adult and pediatric cancers. The restricted expression of SIRPA on macrophages in many tissues argues for targeting SIRPA on macrophages rather than CD47 in CD47/SIRPA blockade therapy. Based on the data available to date, we propose that disruption of the CD47-SIRPA interaction by anti-CD47 antibody would shift the macrophage polarization status from M1 to M2, which is inferred from the 1998 study by Timms et al. In contrast, the anti-SIRPA F(ab') lacking Fc binds to SIRPA on the macrophage, mimics the CD47-SIRPA interaction, and thus maintains M1 polarization. Anti-SIRPA F(ab') also prevents the binding of CD47 to SIRPA, thereby blocking the "don't eat me" signal. The addition of tumor-opsonizing and macrophage-activating antibodies is expected to enhance active tumor phagocytosis.
Topics: CD47 Antigen; Humans; Neuroblastoma; Receptors, Immunologic; Antigens, Differentiation; Macrophages
PubMed: 38920727
DOI: 10.3390/curroncol31060243 -
Journal of Leukocyte Biology Jun 2024Macrophages are essential immune cells for host defense against bacterial pathogens after radiation injury. However, the role of macrophage phagocytosis in infection...
Macrophages are essential immune cells for host defense against bacterial pathogens after radiation injury. However, the role of macrophage phagocytosis in infection following radiation injury remains poorly examined. Extracellular cold-inducible RNA-binding protein (eCIRP) is a damage-associated molecular pattern that dysregulates host immune system responses such as phagocytosis. We hypothesized that radiation-induced eCIRP release impairs macrophage phagocytosis of bacteria. Adult healthy mice were exposed to 6.5-Gy total body irradiation (TBI). Primary peritoneal macrophages isolated from adult healthy mice were exposed to 6.5-Gy radiation. eCIRP-neutralizing monoclonal antibody (mAb) was added to the cell culture prior to irradiation. Bacterial phagocytosis by peritoneal macrophages was assessed using pHrodo Green-labeled E. coli 7 days after irradiation ex vivo and in vitro. Bacterial phagocytosis was also assessed after treatment with recombinant murine CIRP (rmCIRP). Rac1 and ARP2 protein expression in cell lysates and eCIRP levels in the peritoneal lavage were assessed by Western blotting. Bacterial phagocytosis by peritoneal macrophages was significantly decreased after irradiation compared to controls ex vivo and in vitro. Rac1 and ARP2 expression in the peritoneal macrophages were downregulated after TBI. TBI significantly increased eCIRP levels in the peritoneal cavity. rmCIRP significantly decreased bacterial phagocytosis in a dose-dependent manner. eCIRP mAb restored bacterial phagocytosis by peritoneal macrophages after irradiation. Ionizing radiation exposure impairs bacterial phagocytosis by macrophages after irradiation. Neutralization of eCIRP restores the phagocytic ability of macrophages after irradiation. Our findings elucidate a novel mechanism of immune dysfunction and provide a potential new therapeutic approach for limiting infection after radiation injury.
PubMed: 38920274
DOI: 10.1093/jleuko/qiae132 -
Frontiers in Immunology 2024Therapeutic antibodies have become a major strategy to treat oncologic diseases. For chronic lymphocytic leukemia, antibodies against CD20 are used to target and elicit...
INTRODUCTION
Therapeutic antibodies have become a major strategy to treat oncologic diseases. For chronic lymphocytic leukemia, antibodies against CD20 are used to target and elicit cytotoxic responses against malignant B cells. However, efficacy is often compromised due to a suppressive microenvironment that interferes with cellular immune responses. To overcome this suppression, agonists of pattern recognition receptors have been studied which promote direct cytotoxicity or elicit anti-tumoral immune responses. NOD2 is an intracellular pattern recognition receptor that participates in the detection of peptidoglycan, a key component of bacterial cell walls. This detection then mediates the activation of multiple signaling pathways in myeloid cells. Although several NOD2 agonists are being used worldwide, the potential benefit of these agents in the context of antibody therapy has not been explored.
METHODS
Primary cells from healthy-donor volunteers (PBMCs, monocytes) or CLL patients (monocytes) were treated with versus without the NOD2 agonist L18-MDP, then antibody-mediated responses were assessed. In vivo, the Eµ-TCL1 mouse model of CLL was used to test the effects of L18-MDP treatment alone and in combination with anti-CD20 antibody.
RESULTS
Treatment of peripheral blood mononuclear cells with L18-MDP led to activation of monocytes from both healthy donors and CLL patients. In addition, there was an upregulation of activating FcγR in monocytes and a subsequent increase in antibody-mediated phagocytosis. This effect required the NF-κB and p38 signaling pathways. Treatment with L18-MDP plus anti-CD20 antibody in the Eµ-TCL model of CLL led to a significant reduction of CLL load, as well as to phenotypic changes in splenic monocytes and macrophages.
CONCLUSIONS
Taken together, these results suggest that NOD2 agonists help overturn the suppression of myeloid cells, and may improve the efficacy of antibody therapy for CLL.
Topics: Nod2 Signaling Adaptor Protein; Animals; Humans; Receptors, IgG; Mice; Macrophages; Leukemia, Lymphocytic, Chronic, B-Cell; Acetylmuramyl-Alanyl-Isoglutamine; Female; Mice, Inbred C57BL; Signal Transduction; Phagocytosis; Rituximab
PubMed: 38919608
DOI: 10.3389/fimmu.2024.1409333 -
Journal of Neuroinflammation Jun 2024The SARS-CoV-2 virus activates maternal and placental immune responses. Such activation in the setting of other infections during pregnancy is known to impact fetal...
BACKGROUND
The SARS-CoV-2 virus activates maternal and placental immune responses. Such activation in the setting of other infections during pregnancy is known to impact fetal brain development. The effects of maternal immune activation on neurodevelopment are mediated at least in part by fetal brain microglia. However, microglia are inaccessible for direct analysis, and there are no validated non-invasive surrogate models to evaluate in utero microglial priming and function. We have previously demonstrated shared transcriptional programs between microglia and Hofbauer cells (HBCs, or fetal placental macrophages) in mouse models.
METHODS AND RESULTS
We assessed the impact of maternal SARS-CoV-2 on HBCs isolated from 24 term placentas (N = 10 SARS-CoV-2 positive cases, 14 negative controls). Using single-cell RNA-sequencing, we demonstrated that HBC subpopulations exhibit distinct cellular programs, with specific subpopulations differentially impacted by SARS-CoV-2. Assessment of differentially expressed genes implied impaired phagocytosis, a key function of both HBCs and microglia, in some subclusters. Leveraging previously validated models of microglial synaptic pruning, we showed that HBCs isolated from placentas of SARS-CoV-2 positive pregnancies can be transdifferentiated into microglia-like cells (HBC-iMGs), with impaired synaptic pruning behavior compared to HBC models from negative controls.
CONCLUSION
These findings suggest that HBCs isolated at birth can be used to create personalized cellular models of offspring microglial programming.
Topics: Female; Pregnancy; Microglia; Humans; Placenta; COVID-19; Macrophages; Pregnancy Complications, Infectious; SARS-CoV-2; Fetus; Adult; Brain; Mice; Animals
PubMed: 38918792
DOI: 10.1186/s12974-024-03157-w -
Nature Cell Biology Jun 2024Ferroptosis is a distinct form of necrotic cell death caused by overwhelming lipid peroxidation, and emerging evidence indicates a major contribution to organ damage in...
Ferroptosis is a distinct form of necrotic cell death caused by overwhelming lipid peroxidation, and emerging evidence indicates a major contribution to organ damage in multiple pathologies. However, ferroptosis has not yet been visualized in vivo due to a lack of specific probes, which has severely limited the study of how the immune system interacts with ferroptotic cells and how this process contributes to inflammation. Consequently, whether ferroptosis has a physiological role has remained a key outstanding question. Here we identify a distinct, ferroptotic-like, necrotic cell death occurring in vivo during wounding of the Drosophila embryo using live imaging. We further demonstrate that macrophages rapidly engage these necrotic cells within the embryo but struggle to engulf them, leading to prolonged, frustrated phagocytosis and frequent corpse disintegration. Conversely, suppression of the ferroptotic programme during wounding delays macrophage recruitment to the injury site, pointing to conflicting roles for ferroptosis during inflammation in vivo.
PubMed: 38918597
DOI: 10.1038/s41556-024-01450-7 -
The Journal of Clinical Investigation Jun 2024Neutrophil infiltration occurs in a variety of liver diseases, but it is unclear how neutrophils and hepatocytes interact. Neutrophils generally use granule proteases to...
Neutrophil infiltration occurs in a variety of liver diseases, but it is unclear how neutrophils and hepatocytes interact. Neutrophils generally use granule proteases to digest phagocytosed bacteria and foreign substances or neutralize them in neutrophil extracellular traps. In certain pathological states, granule proteases play a destructive role against the host as well. More recently, non-destructive actions of neutrophil granule proteins have been reported, such as modulation of tissue remodeling and metabolism. Here we report a completely different mechanism by which neutrophils act non-destructively, by inserting granules directly into hepatocytes. Specifically, elastase-containing granules were transferred to hepatocytes where elastase selectively degraded intracellular calcium channels to reduce cell proliferation without cytotoxicity. In response, hepatocytes increased expression of serpin E2 and A3, which inhibited elastase activity. Elastase insertion was seen in patient specimens of alcohol-associated hepatitis, and the relationship between elastase-mediated ITPR2 degradation and reduced cell proliferation was confirmed in mouse models. Moreover, neutrophils from patients with alcohol-associated hepatitis were more prone to degranulation and more potent in reducing calcium channel expression than neutrophils from healthy subjects. This non-destructive and reversible action on hepatocytes defines a previously unrecognized role for neutrophils in the transient regulation of epithelial calcium signaling mechanisms.
PubMed: 38916955
DOI: 10.1172/JCI171691 -
Microbiology Spectrum Jun 2024Tuberculosis (TB) is a leading cause of death among infectious diseases worldwide due to latent TB infection, which is the critical step for the successful pathogenic...
UNLABELLED
Tuberculosis (TB) is a leading cause of death among infectious diseases worldwide due to latent TB infection, which is the critical step for the successful pathogenic cycle. In this stage resides inside the host in a dormant and antibiotic-tolerant state. Latent TB infection can also lead to multisystemic diseases because invades virtually all organs, including ocular tissues. Ocular tuberculosis (OTB) occurs when the dormant bacilli within the ocular tissues reactivate, originally seeded by hematogenous spread from pulmonary TB. Histological evidence suggests that retinal pigment epithelium (RPE) cells play a central role in immune privilege and in protection from antibiotic effects, making them an anatomical niche for invading . RPE cells exhibit high tolerance to environmental redox stresses, allowing phagocytosed bacilli to maintain viability in a dormant state. However, the microbiological and metabolic mechanisms determining the interaction between the RPE intracellular environment and phagocytosed are largely unknown. Here, liquid chromatography-mass spectrometry metabolomics were used to illuminate the metabolic state within RPE cells reprogrammed to harbor dormant bacilli and enhance antibiotic tolerance. Timely and accurate diagnosis as well as efficient chemotherapies are crucial in preventing the poor visual outcomes of OTB patients. Unfortunately, the efficacy of current methods is highly limited. Thus, the results will lead to propose a novel therapeutic option to synthetically kill the dormant inside the RPE cells by modulating the phenotypic state of and laying the foundation for a new, innovative regimen for treating OTB.
IMPORTANCE
Understanding the metabolic environment within the retinal pigment epithelium (RPE) cells altered by infection with and mycobacterial dormancy is crucial to identify new therapeutic methods to cure ocular tuberculosis. The present study showed that RPE cellular metabolism is altered to foster intracellular to enter into the dormant and drug-tolerant state, thereby blunting the efficacy of anti-tuberculosis chemotherapy. RPE cells serve as an anatomical niche as the cells protect invading bacilli from antibiotic treatment. LC-MS metabolomics of RPE cells after co-treatment with HO and infection showed that the intracellular environment within RPE cells is enriched with a greater level of oxidative stress. The antibiotic tolerance of intracellular within RPE cells can be restored by a metabolic manipulation strategy such as co-treatment of antibiotic with the most downstream glycolysis metabolite, phosphoenolpyruvate.
PubMed: 38916325
DOI: 10.1128/spectrum.00788-24 -
BioRxiv : the Preprint Server For... Jun 2024Immune cells elicit a continuum of transcriptional and functional states after spinal cord injury (SCI). In mammals, inefficient debris clearance and chronic...
Immune cells elicit a continuum of transcriptional and functional states after spinal cord injury (SCI). In mammals, inefficient debris clearance and chronic inflammation impede recovery and overshadow pro-regenerative immune functions. We found that, unlike mammals, zebrafish SCI elicits transient immune activation and efficient debris clearance, without causing chronic inflammation. Single-cell transcriptomics and inducible genetic ablation showed zebrafish macrophages are highly phagocytic and required for regeneration. Cross-species comparisons between zebrafish and mammalian macrophages identified ( ) as a macrophage-enriched zebrafish gene. Genetic deletion of zebrafish impairs phagocytosis and regeneration, causes aberrant and chronic immune activation, and can be rescued by transplanting wild-type immune precursors into mutants. Conversely, genetic expression of human accelerates debris clearance and regeneration by reprogramming myeloid precursors into activated phagocytes. This study establishes a central requirement for elevated phagocytic capacity to achieve innate spinal cord repair.
PubMed: 38915507
DOI: 10.1101/2024.06.11.598515 -
BioRxiv : the Preprint Server For... Jun 2024Patients with cutaneous T cell lymphoma (CTCL) experience high morbidity and mortality due to skin infections and sepsis, but the causative immune defect is unclear. We...
Patients with cutaneous T cell lymphoma (CTCL) experience high morbidity and mortality due to skin infections and sepsis, but the causative immune defect is unclear. We previously identified high levels of LAIR2, a decoy protein for the inhibitory receptor LAIR1, in advanced CTCL. Mice do not have a LAIR2 homolog, so we used knock-out (KO) mice to model LAIR2 overexpression. In a model of subcutaneous skin infection, KO mice had significantly larger abscesses and areas of dermonecrosis compared to WT. KO exhibited a pattern of increased inflammatory responses in infection and sterile immune stimulation, including increased production of proinflammatory cytokines and myeloid chemokines, neutrophil ROS, and collagen/ECM remodeling pathways. Notably, KO infected skin had a similar bacterial burden and neutrophils and monocytes had equivalent phagocytosis compared to WT. These findings support a model in which lack of LAIR1 signaling causes an excessive inflammatory response that does not improve infection control. CTCL skin lesions harbored similar patterns of increased expression in cytokine and collagen/ECM remodeling pathways, suggesting that high levels of LAIR2 in CTCL recapitulates KO, causing inflammatory tissue damage and compromising host defense against infection.
PubMed: 38915487
DOI: 10.1101/2024.06.13.598864 -
International Journal of Nanomedicine 2024Ginsenoside Rg3 (Rg3) and Panax notoginseng saponins (PNS) can be used for ischemic stroke treatment, however, the lack of targeting to the ischemic region limits the...
PURPOSE
Ginsenoside Rg3 (Rg3) and Panax notoginseng saponins (PNS) can be used for ischemic stroke treatment, however, the lack of targeting to the ischemic region limits the therapeutic effect. To address this, we leveraged the affinity of macrophage membrane proteins for inflamed brain microvascular endothelial cells to develop a macrophage membrane-cloaked liposome loaded with Rg3 and PNS (MM-Lip-Rg3/PNS), which can precisely target brain lesion region through intranasal administration.
METHODS
MM-Lip-Rg3/PNS was prepared by co-extrusion method and was performed by characterization, stability, surface protein, and morphology. The cellular uptake, immune escape ability, and blood-brain barrier crossing ability of MM-Lip-Rg3/PNS were studied in vitro. The in vivo brain targeting, biodistribution and anti-ischemic efficacy of MM-Lip-Rg3/PNS were evaluated in MACO rats, and we determined the diversity of the nasal brain pathway through the olfactory nerve blockade model in rats. Finally, the pharmacokinetics and brain targeting index of MM-Lip-Rg3/PNS were investigated.
RESULTS
Our results indicated that MM-Lip-Rg3/PNS was spherical with a shell-core structure. MM-Lip-Rg3/PNS can avoid mononuclear phagocytosis, actively bind to inflammatory endothelial cells, and have the ability to cross the blood-brain barrier. Moreover, MM-Lip-Rg3/PNS could specifically target ischemic sites, even microglia, increase the cumulative number of drugs in the brain, improve the inflammatory environment of the brain, and reduce the infarct size. By comparing olfactory nerve-blocking rats with normal rats, it was found that there are direct and indirect pathways for nasal entry into the brain. Pharmacokinetics demonstrated that MM-Lip-Rg3/PNS exhibited stronger brain targeting and prolonged drug half-life.
CONCLUSION
MM-Lip-Rg3/PNS might contribute to the accumulation of Rg3 and PNS in the ischemic brain area to improve treatment efficacy. This biomimetic nano-drug delivery system provides a new and promising strategy for the treatment of ischemic stroke.
Topics: Animals; Liposomes; Administration, Intranasal; Ischemic Stroke; Rats; Male; Ginsenosides; Blood-Brain Barrier; Macrophages; Drug Delivery Systems; Rats, Sprague-Dawley; Tissue Distribution; Brain; Biomimetic Materials; Saponins; Mice
PubMed: 38911498
DOI: 10.2147/IJN.S458656