Search Results (55)

Cancer immunotherapy faces significant challenges in treating “cold” tumors, which respond poorly to current strategies. Breast cancer is a major cause of cancer-related mortality in women and is a representative immunosuppressive cold tumor. The luminal A subtype of breast cancer exhibits an immune-cold phenotype, with MCF-7 cells used as a representative cell model. Here, we identified (3β,5α,8α)-5,8-epidioxyergost-6-en-3β-ol (EEO), isolated from Gymnopilus orientispectabilis, as an inducer of immunogenic cell death (ICD) hallmarks in MCF-7 cells, including cell surface exposure of calreticulin (CRT) and the extracellular release of damage-associated molecular patterns (DAMPs), such as ATP and High Mobility Group Box 1 (HMGB1). These ICD-associated events subsequently promoted CRT-dependent dendritic cell (DC) activation in a co-culture system with bone marrow-derived DCs and MCF-7 cells. Furthermore, surface-exposed CRT enhanced the phagocytosis of EEO-treated MCF-7 cells by DCs, and this phagocytic activity promoted DC maturation, as indicated by increased cell surface levels of the maturation markers major histocompatibility complex class II (MHC II) and cluster of differentiation 86 (CD86). Moreover, CRT knockdown in MCF-7 cells reduced surface CRT exposure following EEO treatment, thereby suppressing DC-mediated phagocytosis and subsequent DC maturation. Taken together, these findings suggest that EEO is a promising candidate for enhancing the antitumor efficacy of existing breast cancer immunotherapies through ICD-mediated DC maturation and converting immunologically cold tumors into hot tumors. Full article

The search for new therapeutic principles is essential for treating relapsed/refractory (r/r) acute myeloid leukemia (AML). Novel principles include genome-agnostic differentiation induction, controlling AML-triggering inflammation, potentiating the immune response and ‘normalizing’ AML metabolism. This review summarizes data from a phase I study (10 patients, pts) and three case reports reporting 7 pts on the treatment of r/r AML by reprogramming AML hallmarks using APA, low-dose azacitidine, pioglitazone (PPARα/γ agonist) and all-trans retinoic acid. APA reprograms the r/r AML phenotype in patients with clinically and molecularly/genetically unfavorable risk profiles (17 pts, 16 refractory, one relapsed) in a genome-agnostic manner, restoring the plasticity of AML hallmarks, thereby improving immune surveillance, attenuating inflammation-triggered promotion of AML and distant microbial inflammation (healing of fungal pneumonia during induction of complete remission (CR) with APA), while normalizing leukemia metabolism (restoring phagocytosis and ROS production in leukemic neutrophils). APA induces CR in 10 pts (59%), with only modest hematotoxicity following CR induction. This allows treatment to be carried out in an outpatient setting, including for elderly and comorbid patients. Triple transcriptional modulation, facilitated by epigenetic modelling with azacitidine, targets reprogramming of non-oncogene addiction networks in AML, re-establishing functionally active, closely interrelated myeloid hallmarks and AML cell death genome-agnostically. Full article

Macrophages are key innate immune cells in the host defense against pathogens. Ionizing radiation can impair macrophage functions such as phagocytosis and activate them, potentially exacerbating tissue injury. Macrophage extracellular traps (METs) are formed upon stimulation of macrophages with PAMPs or DAMPs. We hypothesized that macrophages exposed to ionizing radiation can release extracellular traps. Peritoneal macrophages were collected from C57BL/6 mice and subjected to 5 Gy radiation. We performed assays to detect METs, including the immunofluorescence of citrullination of histone H3 and cell-free DNA measurement in cell culture medium as well as cell death. The exposure of ionizing radiation killed a significant number of mouse peritoneal macrophages through pyroptosis, which was mediated by Gasdermin D (GSDMD). The onset of pyroptosis eventually caused METs by suicidal METosis via pyroptosis and vital METosis occurring in the cells surviving after exposure to radiation. We found that exposure of peritoneal macrophages to 5 Gy radiation significantly increased METosis, as revealed by increased levels of citrullinated histone H3 and an increased surface area of extracellular DNA surrounding the cells. We discovered that peptidyl arginine deiminase (PAD) 2 and 4 are required for peritoneal macrophages to generate extracellular traps in response to radiation exposure. Our data demonstrate that the ionizing radiation induces METs via the activation of GSDMD, and we confirmed the requirement of PADs for METosis after exposure to the ionizing radiation. Targeting METs may direct a new therapeutic strategy for mitigating radiation-induced tissue injury. Full article

Background and Objectives: SARS-CoV-2 produces potentially pathogenic molecules, such as single-stranded RNA and spike proteins, which can potentially activate microglial cells. In this study, we aimed to investigate whether SARS-CoV-2 spike protein S1 and mRNA vaccines can cause neurotoxicity directly or through microglial involvement. Materials and Methods: Primary cerebellar granule cell cultures isolated from Wistar rats and organotypic hippocampal slice cultures from transgenic C57BL/6J mice were used in the experiments. Imaging and quantitative analysis of cell viability, proliferation, and phagocytic activity were performed using light and fluorescence microscopy. Results: The exogenous SARS-CoV-2 S1 protein at 50 µg/mL concentration induced neuronal cell death in neuronal–glial co-cultures and stimulated microglial proliferation during the first 3 days of exposure without an effect on inflammatory cytokine secretion. Single application of Tozinameran/Riltozinameran and Original/Omicron BA. 4–5 vaccines did not affect neuronal viability and total neuronal number in cell co-cultures after 7 days of exposure. In contrast, three repeated treatments with mRNA vaccines at 6 ng/mL caused microglial proliferation without affecting microglial phagocytosis and TNF-α release. In organotypic brain slice cultures, only Tozinameran/Riltozinameran stimulated microglial cell proliferation in female brain slices, while male brain slices remained unaffected by both vaccines, indicating sex-dependent effects. Conclusions: The findings suggest that mRNA vaccines do not exert neurotoxic effects in primary neuronal–glial co-cultures, but induce microglial proliferation, particularly in female brains in the absence of inflammatory cytokine release. SARS-CoV-2 S1 protein at high concentrations directly induces neuronal death. Full article

Background: Cannabidiol (CBD) is a major non-psychoactive phytocannabinoid that exerts multiple biological effects in the body. It has been shown to exert anti-cancer effects in a variety of cancer cells, including acute lymphoblastic leukemia of pre-T cell origin (T-ALL), a highly aggressive hematological malignancy. However, the mechanisms underlying CBD’s anti-cancer effects are not fully understood. Furthermore, cancer cells abundantly express surface CD47, which is a negative regulator of phagocytosis and linked with cell survival/death. Little is known about CBD effects on the expression of CD47 in T-ALL cells. The objectives of this study were to address these issues. Methods: Studies were conducted in vitro using Jurkat cells and human peripheral blood mononuclear cells in different culture conditions, CBD concentrations, and in the presence or absence of different reagents. Results: CBD downregulates CD47 expression and induces apoptosis in Jurkat cells. Similar biological effects of CBD were also observed in primary human CD4⁺ T cells, albeit at reduced levels. The CBD’s effects on CD47 expression and apoptosis were not rescued by a cannabinoid receptor (CBR)-2 agonist, a CBR-2 antagonist, or an anion channel blocker. However, these effects on CD47 expression and apoptosis were significantly rescued by a Voltage-Dependent Anion Channel (VDAC)-1 oligomerization inhibitor. Conclusions: Overall, we conclude that CBD downregulates CD47 expression and induces apoptosis involving VDAC-1 oligomerization. Furthermore, they also suggest that CBD’s pro-apoptotic effects on primary human T cells should also be monitored if it is used as an anti-cancer adjuvant or neo-adjuvant therapeutic in cancer patients. Full article

Cryptococcus neoformans (C. neoformans) has emerged as a global pathogen of concern. While much is known about its pathobiology, its management is complicated by strains displaying non-fluconazole susceptibility. This contribution assessed the repurposing of artemisinin (ART) as an anti-Cryptococcus antifungal. An in vitro susceptibility assay was performed to assess the drug response of cells. To establish the ART mode of action, assays examining mitochondrial health were set up. The phagocytosis efficiency of a murine macrophage cell line towards ART-treated and non-treated cells was determined. To complement this, the immunomodulatory effects of ART were further characterised in Galleria mellonella (G. mellonella) by assessing haemocytes’ phagocytosis and expression of immune genes, i.e., insect metalloproteinase inhibitor (IMPI) and hemolin, essential for the insect antimicrobial response. In the end, the survival rate of infected larvae was calculated. We established that ART was antifungal, with cell death triggered by the uncoupling of the cytochrome c (cyt c) from the mitochondria, leading to activation of caspase-3-dependent-like apoptosis. Moreover, treatment induced ultrastructural changes with treated cells appearing more deformed than non-treated cells (p < 0.05). Treatment also increased the susceptibility of cells towards both macrophage and haemocyte phagocytosis compared to non-treated cells (p < 0.05). Importantly, treatment seemed to weaken the cells, decreasing their virulence potential based on analysis of the expression of the immune gene markers, which translated into treatment rescuing 75% of the larvae infected with 0.1 ART-treated cells. These preliminary findings support the repurposing of ART as an anti-Cryptococcus antifungal. Full article

Air pollution, particularly exposure to fine particulate matter (PM_2.5), poses a substantial risk to human health. Diesel exhaust particles (DEPs), a major constituent of PM_2.5, contain chemically reactive components that promote inflammation, oxidative stress, and immune dysfunction. Although the acute toxicity of PM_2.5 and DEPs has been extensively studied, their effects under “sub-toxic” conditions—defined here as exposures that do not cause measurable cytotoxicity based on LDH release but still impair cellular function—remain poorly understood. This study investigated the impact of low-toxicity exposure to DEPs and PM_2.5 on dendritic cell (DC) function using the human plasmacytoid DC-like cell line PMDC05. Cells exposed to DEPs or PM_2.5 exhibited minimal cytotoxicity but accumulated intracellular particles, resulting in impaired endocytosis, phagocytosis, and interferon gene expression upon TLR7 stimulation. These functional impairments were not observed following TLR4 stimulation, suggesting a selective disruption of endolysosomal signalling. The findings demonstrate that DEPs and PM_2.5 can impair innate immune responses without inducing cell death, likely through lysosomal overload and altered intracellular trafficking. This study identifies a non-cytotoxic pathway through which particulate air pollution may compromise antiviral immunity, thereby increasing susceptibility to infection in polluted environments. Strategies aimed at preserving lysosomal integrity and dendritic cell function may help mitigate the immunotoxic effects of airborne particles. Full article

Alpha-1 antitrypsin deficiency (AATD) represents a paradigmatic genetic disorder with well-characterized hepatic manifestations but relatively underexplored pulmonary implications. While liver involvement has been extensively reviewed, the underlying mechanisms of lung disease progression remain poorly understood, particularly regarding immunological pathways and inflammatory processes. The pathophysiology involves defective alpha-1 antitrypsin (AAT) production, including AAT variants that induce neutrophil elastase activity, causing progressive alveolar destruction and sustained inflammation, leading to emphysema, as one of the main components of chronic obstructive pulmonary disease (COPD). AATD and smoking represent major risk factors for COPD, the third leading cause of death worldwide at present. In AATD patients, neutrophils, which constitute the majority of circulating leukocytes, become dysregulated. Under normal conditions, cells perform essential functions, including phagocytosis and neutrophil extracellular trap formation (NETosis); in AATD, however, they accumulate excessively in alveolar spaces due to impaired elastase control. The accumulation of Z-AAT polymers within epithelial cells creates a pathological cycle, acting as chemoattractants that sustain pro-inflammatory responses and contribute to chronic obstructive pulmonary disease development. In addition, monocytes, representing a smaller fraction of leukocytes, migrate to inflammatory sites and differentiate into macrophages while secreting AAT with anti-inflammatory properties. However, in PiZZ patients, this protective mechanism fails, as polymer accumulation within cells reduces both AAT secretion and the number of protective human leukocyte antigen(HLA)-DR-monocyte subsets. In particular, macrophages demonstrate remarkable plasticity, switching between pro-inflammatory M1 (classically activated macrophages) and tissue-repairing M2 (alternatively activated macrophages) phenotypes based on environmental cues. In AATD, this adaptive capability becomes compromised due to intracellular polymer accumulation, leading to impaired phagocytic function and dysregulated cytokine production and ultimately perpetuating chronic inflammation and progressive tissue damage. Recent advances in induced pluripotent stem cell (iPSC) technology have facilitated alveolar epithelial cell (AEC) generation, in addition to the correction of AATD mutations through gene editing systems. Despite the limitations of AAT correction, iPSC-derived organoid models harboring AATD mutations can deliver important insights into disease pathophysiology, while gene editing approaches help demonstrate causality between specific mutations and observed phenotypes. Therefore, in this review, we investigated recent studies that can serve as tools for gene editing and drug development based on recently developed iPSC-related technologies to understand the pathogenesis of AATD. Full article

The TMEM16 (Anoctamin) family comprises a group of transmembrane proteins involved in diverse physiological processes, including ion transport and phospholipid scrambling. TMEM16F (Anoctamin 6), a phospholipid scramblase and nonselective ion channel, plays a central role in membrane remodeling, blood coagulation, immune responses, and cell death pathways through its ability to externalize phosphatidylserine in response to elevated intracellular calcium levels. Consequently, modulating TMEM16F activity has emerged as a promising strategy for the development of new therapeutic applications. Despite the functional importance of TMEM16F, TMEM16F modulators have received little study. In a previous study, we generated TMEM16F-specific affibodies by biopanning a phage display library for affibodies that bind to brain-specific TMEM16F (hTMEM16F) variant 1. In this study, we selected six other affibodies from among the 38 previously sequenced affibody candidates and characterized them. After purification, we confirmed that two of these affibodies bound to human TMEM16F with high affinity. To provide functional insights into how these affibodies modulate TMEM16F activity, we tested whether they could exert functional effects at the cellular level. Finally, we show that TMEM16F affibody attenuated the neuronal cell death induced by glutamate and microglial phagocytosis, suggesting that these affibodies might have potential therapeutic and diagnostic applications. Full article

Legg–Calvé–Perthes disease is a juvenile ischemic osteonecrosis (ON) of the femoral head. A disruption of blood supply to the femoral head produces extensive cell death and necrotic debris. Macrophages are innate immune cells recruited to the necrotic bone to orchestrate the repair process. However, the role macrophages play in the ON repair process is still not elucidated. The purpose of this study was to determine the effect of artificial necrotic bone fluid (NBF) on porcine peripheral blood mononuclear cell (PBMC)-derived macrophages. Monocytes were positively selected by CD14 MicroBeads from pig PBMCs. After maturation, cells were treated with no stimulant (Con), LPS + IFNγ (M1), IL4 + IL13 (M2), or NBF. All culture supernatants and cells were harvested for ELISA, Western blot, FACS, RT-qPCR and bulk RNAseq. The Western blot and ELISA showed that only the M1 condition elevated the protein level of pro-inflammatory cytokines. The FACS results indicated that percentage of CD8086+ (M1 marker) cells was significantly lower in the M2 vs. other conditions, whereas the relative median fluorescence intensity of CD8086 was significantly higher in the M1 vs. other conditions. The NBF did not show any significant change compared to the Con. mRNA analysis showed significantly increased IL1β and IL8 expression in the M1 vs. Con scenario. TNFα expression was significantly decreased in the M2 vs. Con scenario. Interestingly, the NBF did not induce pro-inflammatory gene expression. For bulk RNAseq, the Gene Set Enrichment Analyses of the M1-stimulated cells revealed the enrichment of pro-inflammatory gene sets. For the M2, most of the enriched categories were related to the down-regulation of inflammation. For the NBF, the most enriched categories were related to the down-regulation of protein translation and mitochondrial metabolism. We further confirmed the suppressive effects of NBF on macrophage functions using Seahorse Cell Mito Stress Tests, ¹³C-glucose metabolic flux analysis, mitochondrial ROS detection via MitoSOX^TM staining, and phagocytosis assay. Taken together, these results revealed that the artificial NBF down-regulates the overall cellular activity and energy metabolism of macrophages. Full article

Air pollution, particularly from vehicular emissions, has emerged as a critical environmental health concern, contributing to a global estimated 7 million premature deaths annually. Diesel exhaust, a major component of urban air pollution, contains fine particulate matter and gases that evade respiratory filtration, penetrating deep into the lungs and triggering oxidative stress, inflammation, and immune dysregulation. Epidemiological and in vitro studies have linked diesel exhaust exposure to respiratory diseases such as asthma, chronic obstructive pulmonary disease, pulmonary fibrosis, and lung cancer, with immunological mechanisms playing a central role. Diesel exhaust particles induce oxidative stress, impair macrophage phagocytosis, and skew T-cell polarization toward pro-inflammatory Th2 and Th17 responses, exacerbating chronic inflammation and tissue damage. Despite these insights, significant gaps remain in understanding the precise immunomodulatory pathways and long-term systemic effects of diesel exhaust exposure. While animal models and in vitro studies provide valuable data, they often fail to capture the complexity of human exposure and immune responses. Further research is needed to elucidate the mechanisms underlying diesel exhaust-induced immune dysregulation, particularly in vulnerable populations with pre-existing respiratory conditions. This review focuses on summarizing the current knowledge and identifying gaps that are essential for developing targeted interventions and policies to mitigate the adverse health impacts of diesel exhaust and improve respiratory health outcomes globally. Full article

The structural and functional integrity of the retinal pigment epithelium (RPE) plays a key role in the normal functioning of the visual system. RPE cells are characterized by an efficient system of photoreceptor outer segment phagocytosis, high metabolic activity, and risk of oxidative damage. RPE dysfunction is a common pathological feature in various retinal diseases. Dysregulation of RPE cell proteostasis and redox homeostasis is accompanied by increased reactive oxygen species generation during the impairment of phagocytosis, lysosomal and mitochondrial failure, and an accumulation of waste lipidic and protein aggregates. They are the inducers of RPE dysfunction and can trigger specific pathways of cell death. Autophagy serves as important mechanism in the endogenous defense system, controlling RPE homeostasis and survival under normal conditions and cellular responses under stress conditions through the degradation of intracellular components. Impairment of the autophagy process itself can result in cell death. In this review, we summarize the classical types of oxidative stress-induced autophagy in the RPE with an emphasis on autophagy mediated by molecular chaperones. Heat shock proteins, which represent hubs connecting the life supporting pathways of RPE cells, play a special role in these mechanisms. Regulation of oxidative stress-counteracting autophagy is an essential strategy for protecting the RPE against pathological damage when preventing retinal degenerative disease progression. Full article

Neutrophils, the most abundant circulating white blood cells, are essential for the initial immune response to infection and injury. Emerging research reveals a dualistic function of neutrophils in cancer, where they can promote or inhibit tumor progression. This dichotomy is influenced by the tumor microenvironment, with neutrophils capable of remodeling the extracellular matrix, promoting angiogenesis, or alternatively inducing cancer cell death and enhancing immune responses. An intriguing yet poorly understood aspect of neutrophil–cancer interactions is the phenomenon of neutrophil engulfment by cancer cells, which has been observed across various cancers. This process, potentially mediated by LC3-associated phagocytosis (LAP), raises questions about whether it serves as a mechanism for immune evasion or contributes to tumor cell death through pathways like ferroptosis. This review examines current knowledge on neutrophil development, their roles in cancer, and the mechanisms of LAP in neutrophil engulfment by tumor cells. We discuss how manipulating LAP impacts cancer progression and may represent a therapeutic strategy. We also explore neutrophils’ potential as delivery vehicles for cancer therapeutic agents. Understanding the complex functions of tumor-associated neutrophils (TANs) and the molecular mechanisms underlying LAP in cancer may open new avenues for effective therapeutic interventions and mitigate potential risks. Full article

Osteonecrosis (ON) of the femoral head (ONFH) is a devastating bone disease affecting over 20 million people worldwide. ONFH is caused by a disruption of the blood supply, leading to necrotic cell death and increased inflammation. Macrophages are the key cells mediating the inflammatory responses in ON. It is unclear what the dynamic phenotypes of macrophages are and what mechanisms may affect macrophage polarization and, therefore, the healing process. In our preliminary study, we found that there is an invasion of macrophages into the repair tissue during ON healing. Interestingly, in both ONFH patients and a mouse ON model, fat was co-labeled within macrophages using immunofluorescence staining, indicating the phagocytosis of fat by macrophages. To study the effects of fat phagocytosis on the macrophage phenotype, we set up an in vitro macrophage and fat co-culture system. We found that fat phagocytosis significantly decreased M1 marker expression, such as IL1β and iNOS, in macrophages, whereas the expression of the M2 marker Arg1 was significantly increased with fat phagocytosis. To investigate whether the polarization change is indeed mediated by phagocytosis, we treated the cells with Latrunculin A (LA, which inhibits actin polymerization and phagocytosis). LA supplementation significantly reversed the polarization marker gene changes induced by fat phagocytosis. To provide an unbiased transcriptional gene analysis, we submitted the RNA for bulk RNA sequencing. Differential gene expression (DGE) analysis revealed that the top upregulated genes were related to anti-inflammatory responses, while proinflammatory genes were significantly downregulated. Additionally, using pathway enrichment and network analyses (Metascape), we confirmed that gene-enriched categories related to proinflammatory responses were significantly downregulated in macrophages with fat phagocytosis. Finally, we validated the similar macrophage phenotype changes in vivo. To summarize, we discovered that fat phagocytosis occurs in both ONFH patients and an ON mouse model, which inhibits proinflammatory responses with increased anabolic gene expression in macrophages. This fat-phagocytosis-induced macrophage phenotype is consistent with the in vivo changes shown in the ON mouse model. Our study reveals a novel phagocytosis-mediated macrophage polarization mechanism in ON, which fills in our knowledge gaps of macrophage functions and provides new concepts in macrophage immunomodulation as a promising treatment for ON. Full article

Mycobacterium tuberculosis (Mtb) is the causative agent of tuberculosis (TB), a prevalent infectious disease affecting populations worldwide. A classic trait of TB pathology is the formation of granulomas, which wall off the pathogen, via the innate and adaptive immune systems. Some key players involved include tumor necrosis factor-alpha (TNF-α), foamy macrophages, type I interferons (IFNs), and reactive oxygen species, which may also show overlap with cell death pathways. Additionally, host cell death is a primary method for combating and controlling Mtb within the body, a process which is influenced by both host and bacterial factors. These cell death modalities have distinct molecular mechanisms and pathways. Programmed cell death (PCD), encompassing apoptosis and autophagy, typically confers a protective response against Mtb by containing the bacteria within dead macrophages, facilitating their phagocytosis by uninfected or neighboring cells, whereas necrotic cell death benefits the pathogen, leading to the release of bacteria extracellularly. Apoptosis is triggered via intrinsic and extrinsic caspase-dependent pathways as well as caspase-independent pathways. Necrosis is induced via various pathways, including necroptosis, pyroptosis, and ferroptosis. Given the pivotal role of host cell death pathways in host defense against Mtb, therapeutic agents targeting cell death signaling have been investigated for TB treatment. This review provides an overview of the diverse mechanisms underlying Mtb-induced host cell death, examining their implications for host immunity. Furthermore, it discusses the potential of targeting host cell death pathways as therapeutic and preventive strategies against Mtb infection. Full article