Prostaglandin E2-Induced AKT Activation Regulates the Life Span of Short-Lived Plasma Cells by Attenuating IRE1α Hyperactivation.

The mechanism regulating the life span of short-lived plasma cells (SLPCs) remains poorly understood. Here we demonstrated that the EP4-mediated activation of AKT by PGE2 was required for the proper control of inositol-requiring transmembrane kinase endoribonuclease-1α (IRE1α) hyperactivation and hence the endoplasmic reticulum (ER) homeostasis in IgM-producing SLPCs. Disruption of the PGE2-EP4-AKT signaling pathway resulted in IRE1α-induced activation of JNK, leading to accelerated death of SLPCs. Consequently, Ptger4-deficient mice (C57BL/6) exhibited a markedly impaired IgM response to T-independent Ags and increased susceptibility to Streptococcus pneumoniae infection. This study reveals a highly selective impact of the PGE2-EP4 signal on the humoral immunity and provides a link between ER stress response and the life span of SLPCs.

Cutting Edge: l-Arginine Transfer from Antigen-Presenting Cells Sustains CD4+ T Cell Viability and Proliferation.

Metabolomics analyses suggest changes in amino acid abundance, particularly l-arginine (L-ARG), occur in patients with tuberculosis. Immune cells require L-ARG to fuel effector functions following infection. We have previously described an L-ARG synthesis pathway in immune cells; however, its role in APCs has yet to be uncovered. Using a coculture system with mycobacterial-specific CD4+ T cells, we show APC L-ARG synthesis supported T cell viability and proliferation, and activated T cells contained APC-derived L-ARG. We hypothesize that APCs supply L-ARG to support T cell activation under nutrient-limiting conditions. This work expands the current model of APC-T cell interactions and provides insight into the effects of nutrient availability in immune cells.

SARS-CoV-2 spike protein inhibits growth of prostate cancer: a potential role of the COVID-19 vaccine killing two birds with one stone.

To investigate the effects of isolated SARS-CoV-2 spike protein on prostate cancer cell survival. The effects of SARS-CoV-2 spike protein on LNCaP prostate cancer cell survival were assessed using clonogenic cell survival assay, quick cell proliferation assay, and caspase-3 activity kits. RT-PCR and immunohistochemistry were performed to investigate underlying molecular mechanisms. SARS-CoV-2 spike protein was found to inhibit prostate cancer cell proliferation as well as promote apoptosis. Further investigation revealed that anti-proliferative effects were associated with downregulation of the pro-proliferative molecule cyclin-dependent kinase 4 (CDK4). The increased rate of apoptosis was associated with the upregulation of pro-apoptotic molecule Fas ligand (FasL). SARS-CoV-2 spike protein inhibits the growth of LNCaP prostate cancer cells in vitro by a two-pronged approach of downregulating the expression of CDK4 and upregulating FasL. The introduction of SARS-CoV-2 spike protein into the body via COVID-19 vaccination may have the potential to inhibit prostate cancer in patients. This potential beneficial association between COVID-19 vaccines and prostate cancer inhibition will require more extensive studies before any conclusions can be drawn about any in vivo effects in a human model.

Sialic acid blockade in dendritic cells enhances CD8+ T cell responses by facilitating high-avidity interactions.

Sialic acids are negatively charged carbohydrates that cap the glycans of glycoproteins and glycolipids. Sialic acids are involved in various biological processes including cell-cell adhesion and immune recognition. In dendritic cells (DCs), the major antigen-presenting cells of the immune system, sialic acids emerge as important regulators of maturation and interaction with other lymphocytes including T cells. Many aspects of how sialic acids regulate DC functions are not well understood and tools and model systems to address these are limited. Here, we have established cultures of murine bone marrow-derived DCs (BMDCs) that lack sialic acid expression using a sialic acid-blocking mimetic Ac53FaxNeu5Ac. Ac53FaxNeu5Ac treatment potentiated BMDC activation via toll-like receptor (TLR) stimulation without affecting differentiation and viability. Sialic acid blockade further increased the capacity of BMDCs to induce antigen-specific CD8+ T cell proliferation. Transcriptome-wide gene expression analysis revealed that sialic acid mimetic treatment of BMDCs induces differential expression of genes involved in T cell activation, cell-adhesion, and cell-cell interactions. Subsequent cell clustering assays and single cell avidity measurements demonstrated that BMDCs with reduced sialylation form higher avidity interactions with CD8+ T cells. This increased avidity was detectable in the absence of antigens, but was especially pronounced in antigen-dependent interactions. Together, our data show that sialic acid blockade in BMDCs ameliorates maturation and enhances both cognate T cell receptor-MHC-dependent and independent T cell interactions that allow for more robust CD8+ T cell responses.

Bcl-2 Is Necessary to Counteract Bim and Promote Survival of TCRαß+CD8αα+ Intraepithelial Lymphocyte Precursors in the Thymus.

The precursors of TCRαß+CD8αα+ intraepithelial lymphocytes (IEL) arise in the thymus through a complex process of agonist selection. We and others have shown that the proapoptotic protein, Bim, is critical to limit the number of thymic IEL precursors (IELp), as loss of Bim at the CD4+CD8+ double-positive stage of development drastically increases IELp. The factors determining this cell death versus survival decision remain largely unknown. In this study, we used CD4CreBcl2f/f mice to define the role of the antiapoptotic protein Bcl-2 and CD4CreBcl2f/fBimf/f mice to determine the role of Bcl-2 in opposing Bim to promote survival of IELp. First, in wild-type mice, we defined distinct subpopulations within PD-1+CD122+ IELp, based on their expression of Runx3 and α4ß7. Coexpression of α4ß7 and Runx3 marked IELp that were most dependent upon Bcl-2 for survival. Importantly, the additional loss of Bim restored Runx3+α4ß7+ IELp, showing that Bcl-2 antagonizes Bim to enable IELp survival. Further, the loss of thymic IELp in CD4CreBcl2f/f mice also led to a dramatic loss of IEL in the gut, and the additional loss of Bim restored gut IEL. The loss of gut IEL was due to both reduced seeding by IELp from the thymus as well as a requirement for Bcl-2 for peripheral IEL survival. Together, these findings highlight subset-specific and temporal roles for Bcl-2 in driving the survival of TCRαß+CD8αα+ IEL and thymic IELp.

Integrated stress response restricts macrophage necroptosis.

The integrated stress response (ISR) regulates cellular homeostasis and cell survival following exposure to stressors. Cell death processes such as apoptosis and pyroptosis are known to be modulated by stress responses, but the role of the ISR in necroptosis is poorly understood. Necroptosis is an inflammatory, lytic form of cell death driven by the RIPK3-MLKL signaling axis. Here, we show that macrophages that have induced the ISR are protected from subsequent necroptosis. Consistent with a reduction in necroptosis, phosphorylation of RIPK1, RIPK3, and MLKL is reduced in macrophages pre-treated with ISR-inducing agents that are challenged with necroptosis-inducing triggers. The stress granule component DDX3X, which is involved in ISR-mediated regulation of pyroptosis, is not required for protecting ISR-treated cells from necroptosis. Disruption of stress granule assembly or knockdown of Perk restored necroptosis in pre-stressed cells. Together, these findings identify a critical role for the ISR in limiting necroptosis in macrophages.

Interleukin-7 Biology and Its Effects on Immune Cells: Mediator of Generation, Differentiation, Survival, and Homeostasis.

Interleukin-7 (IL-7), a molecule known for its growth-promoting effects on progenitors of B cells, remains one of the most extensively studied cytokines. It plays a vital role in health maintenance and disease prevention, and the congenital deficiency of IL-7 signaling leads to profound immunodeficiency. IL-7 contributes to host defense by regulating the development and homeostasis of immune cells, including T lymphocytes, B lymphocytes, and natural killer (NK) cells. Clinical trials of recombinant IL-7 have demonstrated safety and potent immune reconstitution effects. In this article, we discuss IL-7 and its functions in immune cell development, drawing on a substantial body of knowledge regarding the biology of IL-7. We aim to answer some remaining questions about IL-7, providing insights essential for designing new strategies of immune intervention.

EZH2 Inhibition Compromises α4-1BB-Mediated Antitumor Efficacy by Reducing the Survival and Effector Programming of CD8+ T Cells.

Enhancer of Zeste Homolog 2 (EZH2) inhibitors (EZH2i) are approved to treat certain cancer types. Previous studies have suggested the potential to combine EZH2i with immune checkpoint blockade targeting coinhibitory receptors like PD-(L)1 and CTLA-4, but whether it can also enhance the activity of agents targeting costimulatory receptors is not known. Here, we explore the combination between EZH2i and an agonist antibody targeting the T cell costimulatory receptor 4-1BB (α4-1BB). Our data show that EZH2i compromise the efficacy of α4-1BB in both CT26 colon carcinoma and in an in vivo protein immunization model. We link this to reduced effector survival and increased BIM expression in CD8+ T cells upon EZH2i treatment. These data support the requirement of EZH2 function in 4-1BB-mediated CD8+ T cell expansion and effector programming and emphasize the consideration that must be given when combining such antitumoral therapies.

Human Adenovirus Serotype 3 Infection Modulates the Biogenesis and Composition of Lung Cell-Derived Extracellular Vesicles.

Adenovirus (Ad) is a major causal agent of acute respiratory infections. However, they are a powerful delivery system for gene therapy and vaccines. Some Ad serotypes antagonize the immune system leading to meningitis, conjunctivitis, gastroenteritis, and/or acute hemorrhagic cystitis. Studies have shown that the release of small, membrane-derived extracellular vesicles (EVs) may offer a mechanism by which viruses can enter cells via receptor-independent entry and how they influence disease pathogenesis and/or host protection considering their existence in almost all bodily fluids. We proposed that Ad3 could alter EV biogenesis, composition, and trafficking and may stimulate various immune responses in vitro. In the present study, we evaluated the impact of in vitro infection with Ad3 vector on EV biogenesis and composition in the human adenocarcinoma lung epithelial cell line A549. Cells were infected in an exosome-free media at different multiplicity of infections (MOIs) and time points. The cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl tetrazolium bromide (MTT) and fluorometric calcein-AM. EVs were isolated via ultracentrifugation. Isolated EV proteins were quantified and evaluated via nanoparticle tracking, transmission electron microscopy, sodium dodecyl sulfate-polyacrylamide gel electrophoresis, and immunoblotting assays. The cell viability significantly decreased with an increase in MOI and incubation time. A significant increase in particle mean sizes, concentrations, and total EV protein content was detected at higher MOIs when compared to uninfected cells (control group). A549 cell-derived EVs revealed the presence of TSG101, tetraspanins CD9 and CD63, and heat shock proteins 70 and 100 with significantly elevated levels of Rab5, 7, and 35 at higher MOIs (300, 750, and 1500) when compared to the controls. Our findings suggested Ad3 could modulate EV biogenesis, composition, and trafficking which could impact infection pathogenesis and disease progression. This study might suggest EVs could be diagnostic and therapeutic advancement to Ad infections and other related viral infections. However, further investigation is warranted to explore the underlying mechanism(s).

FUCA2 Is a Prognostic Biomarker and Correlated With an Immunosuppressive Microenvironment in Pan-Cancer.

Background: The expression of Fucosidase, alpha-L-2 (FUCA2) varies across tumors. However, its role in various tumor types and relationship with the tumor immune microenvironment (TIME) is poorly defined. Methods: We analyzed profiles of FUCA2 expression using datasets from The Cancer Genome Atlas (TCGA) and Genotype-Tissue Expression (GTEx) databases. Next, gene alteration, clinical characteristics and prognostic values of FUCA2 were elucidated based on TCGA pan-cancer data. This was followed by gene set enrichment analysis by R software. Relationships between FUCA2 expression and immune infiltration and immune-related genes were also evaluated. Moreover, the association of immune cell infiltration with FUCA2 expression was evaluated across three different sources of immune cell infiltration data, namely the TIMER online, ImmuCellAI databases, as well as a published study. In addition, MTT assays was also conducted to validate the oncogene role of FUCA2 in lung cancer cells. Results: FUCA2 was upregulated in most tumors, and this was significantly associated with poor survival rates. Gene set enrichment analysis uncovered that FUCA2 correlated with immune pathways in different tumor types. FUCA2 expression was positively related to tumor associated macrophages (TAMs), especially M2-like TAMs. Moreover, FUCA2 level showed a positive relationship with most immunosuppression genes, including programmed death-ligand 1 (PD-L1), transforming growth factor beta 1 (TGFB1), and interleukin-10 (IL10) in most cancer types. FUCA2 knockdown inhibited the cell viability in lung cancer cells. Conclusions: Our study reveals that FUCA2 is a potential oncogene and is indicative biomarker of a worse prognosis in pan-cancer. High FUCA2 expression may contribute to increased infiltration of TAMs and associates with an immunosuppressive microenvironment, providing a potential target for tumor therapy.

Macrophages and cancer stem cells: a malevolent alliance.

Myeloid cells infiltrating tumors are gaining ever growing attention in the last years because their pro-tumor and immunosuppressive functions are relevant for disease progression and therapeutic responses. The functional ambiguity of tumor-associated macrophages (TAMs), mostly promoting tumor evolution, is a challenging hurdle. This is even more evident in the case of cancer stem cells (CSCs); as active participants in the specialized environment of the cancer stem cell niche, TAMs initiate a reciprocal conversation with CSCs. TAMs contribute to protect CSCs from the hostile environment (exogenous insults, toxic compounds, attacks from the immune cells), and produce several biologically active mediators that modulate crucial developmental pathways that sustain cancer cell stemness. In this review, we have focused our attention on the interaction between TAMs and CSCs; we describe how TAMs impact on CSC biology and, in turn, how CSCs exploit the tissue trophic activity of macrophages to survive and progress. Since CSCs are responsible for therapy resistance and tumor recurrence, they are important therapeutic targets. In view of the recent success in oncology obtained by stimulating the immune system, we discuss some macrophage-targeted therapeutic strategies that may also affect the CSCs and interrupt their malevolent alliance.

What are the immunopharmacological effects of furazolidone? A systematic review.

Furazolidone (FZD) is a widely used drug in human and veterinary medicine, and has antibacterial and antiprotozoal action. Although it is widely used as a therapy in various pathological conditions, studies on the efficacy of FZD associated with immune responses are still limited. In this review, we seek to describe which immunopharmacological responses are caused by the administration of FZD. The study followed the recommendations of the Preferred Reporting Items for Systematic Reviews and Meta-Analysis (PRISMA). A systematic review of clinical trials and in vitro and in vivo experimental studies was carried out, which resulted in 943 papers, of which 35 were considered eligible and, of these 35, 4 were selected for analysis. The studies listed indicated that administration of FZD can modulate pro- or anti-inflammatory pathways, with a probable increase in the expression of reactive oxygen species and a modulation of apoptotic pathways.

Interleukin-17 and Th17 Lymphocytes Directly Impair Motoneuron Survival of Wildtype and FUS-ALS Mutant Human iPSCs.

Amyotrophic lateral sclerosis (ALS) is a progressive disease leading to the degeneration of motor neurons (MNs). Neuroinflammation is involved in the pathogenesis of ALS; however, interactions of specific immune cell types and MNs are not well studied. We recently found a shift toward T helper (Th)1/Th17 cell-mediated, pro-inflammatory immune responses in the peripheral immune system of ALS patients, which positively correlated with disease severity and progression. Whether Th17 cells or their central mediator, Interleukin-17 (IL-17), directly affects human motor neuron survival is currently unknown. Here, we evaluated the contribution of Th17 cells and IL-17 on MN degeneration using the co-culture of iPSC-derived MNs of fused in sarcoma (FUS)-ALS patients and isogenic controls with Th17 lymphocytes derived from ALS patients, healthy controls, and multiple sclerosis (MS) patients (positive control). Only Th17 cells from MS patients induced severe MN degeneration in FUS-ALS as well as in wildtype MNs. Their main effector, IL-17A, yielded in a dose-dependent decline of the viability and neurite length of MNs. Surprisingly, IL-17F did not influence MNs. Importantly, neutralizing IL-17A and anti-IL-17 receptor A treatment reverted all effects of IL-17A. Our results offer compelling evidence that Th17 cells and IL-17A do directly contribute to MN degeneration.

Selenium-GPX4 axis protects follicular helper T cells from ferroptosis.

Follicular helper T (TFH) cells are a specialized subset of CD4+ T cells that essentially support germinal center responses where high-affinity and long-lived humoral immunity is generated. The regulation of TFH cell survival remains unclear. Here we report that TFH cells show intensified lipid peroxidation and altered mitochondrial morphology, resembling the features of ferroptosis, a form of programmed cell death that is driven by iron-dependent accumulation of lipid peroxidation. Glutathione peroxidase 4 (GPX4) is the major lipid peroxidation scavenger and is necessary for TFH cell survival. The deletion of GPX4 in T cells selectively abrogated TFH cells and germinal center responses in immunized mice. Selenium supplementation enhanced GPX4 expression in T cells, increased TFH cell numbers and promoted antibody responses in immunized mice and young adults after influenza vaccination. Our findings reveal the central role of the selenium-GPX4-ferroptosis axis in regulating TFH homeostasis, which can be targeted to enhance TFH cell function in infection and following vaccination.

PIR-B Regulates CD4+ IL17a+ T-Cell Survival and Restricts T-Cell-Dependent Intestinal Inflammatory Responses.

BACKGROUND & AIMS: CD4+ T cells are regulated by activating and inhibitory cues, and dysregulation of these proper regulatory inputs predisposes these cells to aberrant inflammation and exacerbation of disease. We investigated the role of the inhibitory receptor paired immunoglobulin-like receptor B (PIR-B) in the regulation of the CD4+ T-cell inflammatory response and exacerbation of the colitic phenotype. METHODS: We used Il10-/- spontaneous and CD4+CD45RBhi T-cell transfer models of colitis with PIR-B-deficient (Pirb-/-) mice. Flow cytometry, Western blot, and RNA sequencing analysis was performed on wild-type and Pirb-/- CD4+ T cells. In silico analyses were performed on RNA sequencing data set of ileal biopsy samples from pediatric CD and non-inflammatory bowel disease patients and sorted human memory CD4+ T cells. RESULTS: We identified PIR-B expression on memory CD4+ interleukin (IL)17a+ cells. We show that PIR-B regulates CD4+ T-helper 17 cell (Th17)-dependent chronic intestinal inflammatory responses and the development of colitis. Mechanistically, we show that the PIR-B- Src-homology region 2 domain-containing phosphatase-1/2 axis tempers mammalian target of rapamycin complex 1 signaling and mammalian target of rapamycin complex 1-dependent caspase-3/7 apoptosis, resulting in CD4+ IL17a+ cell survival. In silico analyses showed enrichment of transcriptional signatures for Th17 cells (RORC, RORA, and IL17A) and tissue resident memory (HOBIT, IL7R, and BLIMP1) networks in PIR-B+ murine CD4+ T cells and human CD4+ T cells that express the human homologue leukocyte immunoglobulin-like receptor subfamily B member 3 (LILRB3). High levels of LILRB3 expression were associated strongly with mucosal injury and a proinflammatory Th17 signature, and this signature was restricted to a treatment-naïve, severe pediatric CD population. CONCLUSIONS: Our findings show an intrinsic role for PIR-B/LILRB3 in the regulation of CD4+ IL17a+ T-cell pathogenic memory responses.

In Vivo Tracking of Cell Viability for Adoptive Natural Killer Cell-Based Immunotherapy by Ratiometric NIR-II Fluorescence Imaging.

The therapeutic efficacy of natural killer (NK) cells-based immunotherapy is greatly related with the survival of transplanted NK cells. However, no effective strategy was reported to monitor NK cell viability in adoptive immunotherapy in vivo. Herein, we develop a ratiometric NIR-II fluorescence imaging strategy to quantitively track and visualize the adoptive NK cell viability in vivo in real-time. The nanoprobe consists of lanthanide-based down-conversion nanoparticles (DCNP) coated with IR786s, a reactive oxygen species (ROS) sensitive to NIR dye, which was directly labeled with NK cells. Upon cell death, the excessive ROS generation occurred within NK cells, along with IR786s degradation, turning on NIR-II fluorescent signal at 1550 nm of DCNP under 808-nm excitation, while the fluorescent signal at 1550 nm of DCNP under 980-nm excitation was stable. Such an intracellular ROS-induced ratiometric NIR-II fluorescent signal was validated to correlate well with NK cell viability in vivo. Using this nanoreporter, we further demonstrated that co-treatment with IL-2, IL-15, and IL-21 could improve NK cell viability in vivo, achieving enhanced immunotherapy for orthotopic hepatocellular carcinoma. Overall, this strategy allows for longitudinal and quantitative tracking of NK cell viability in NK cell-based immunotherapy.

Differential sensitivity of inflammatory macrophages and alternatively activated macrophages to ferroptosis.

Acumulation of oxidized membrane lipids ultimately results in ferroptotic cell death, which can be prevented by the selenoenzyme glutathione peroxidase 4 (Gpx4). In vivo conditions promoting ferroptosis and susceptible cell types are still poorly defined. In this study, we analyzed the conditional deletion of Gpx4 in mice specifically in the myeloid cell lineages. Surprisingly, development and maintenance of LysM+ macrophages and neutrophils, as well as CD11c+ monocyte-derived macrophages and dendritic cells were unaffected in the absence of Gpx4. Gpx4-deficient macrophages mounted an unaltered proinflammatory cytokine response including IL-1ß production following stimulation with TLR ligands and activation of several inflammasomes. Accordingly, Gpx4fl/fl LysM-cre mice were protected from bacterial and protozoan infections. Despite having the capacity to differentiate to alternatively activated macrophages (AAM), these cells lacking Gpx4 triggered ferroptosis both in vitro and in vivo following IL-4 overexpression and nematode infection. Exposure to nitric oxide restored viability of Gpx4-deficient AAM, while inhibition of iNOS in proinflammatory macrophages had no effect. These data together suggest that activation cues of tissue macrophages determine sensitivity to lipid peroxidation and ferroptotic cell death.

CD8+ T cell survival in lethal fungal sepsis was ameliorated by T-cell-specific mTOR deletion.

Lethal fungal sepsis causes high morbidity and mortality in intensive care patients. Fungal infections have an immunological basis, and it has been shown in recent studies that decreased CD8+ T-cell count in fungal infections is related to prognosis, while the underlying mechanism is still unclear. Here, a lethal fungal sepsis model induced by candidemia was created and we found a decreased CD8+ T-cell count and exaggerated apoptosis. Simultaneously, expression of light chain (LC)3B in CD8+ T cells increased, along with increased autophagosomes and accumulation of p62 in infected mice. We regulated the activity of the mammalian target of rapamycin (mTOR) pathway using T-cell-specific mTOR/ TSC1 deletion mice. We observed increased number of autophagosomes and expression of LC3B in CD8+T cells after T-cell-specific mTOR knockout, while accumulation of p62 was not ameliorated, and there was no increase in the number of autolysosomes. Apoptosis rate and expression of BIM, a pro-apoptotic gene, decreased in CD8+ T cells in mTOR-deletion mice but increased in TSC1-deletion mice. Our results showed increased CD8+ T-cell death in spleen of lethal fungal sepsis mice, and decreased expression of mTOR ameliorated CD8+ T-cell survival. mTOR may be a possible target to reverse CD8+ T-cell immune dysfunction in lethal fungal sepsis.

Epstein-Barr Virus Induced Cytidine Metabolism Roles in Transformed B-Cell Growth and Survival.

Epstein-Barr virus (EBV) is associated with 200,000 cancers annually, including B-cell lymphomas in immunosuppressed hosts. Hypomorphic mutations of the de novo pyrimidine synthesis pathway enzyme cytidine 5' triphosphate synthase 1 (CTPS1) suppress cell-mediated immunity, resulting in fulminant EBV infection and EBV+ central nervous system (CNS) lymphomas. Since CTP is a critical precursor for DNA, RNA, and phospholipid synthesis, this observation raises the question of whether the isozyme CTPS2 or cytidine salvage pathways help meet CTP demand in EBV-infected B cells. Here, we found that EBV upregulated CTPS1 and CTPS2 with distinct kinetics in newly infected B cells. While CRISPR CTPS1 knockout caused DNA damage and proliferation defects in lymphoblastoid cell lines (LCLs), which express the EBV latency III program observed in CNS lymphomas, double CTPS1/2 knockout caused stronger phenotypes. EBNA2, MYC, and noncanonical NF-κB positively regulated CTPS1 expression. CTPS1 depletion impaired EBV lytic DNA synthesis, suggesting that latent EBV may drive pathogenesis with CTPS1 deficiency. Cytidine rescued CTPS1/2 deficiency phenotypes in EBV-transformed LCLs and Burkitt B cells, highlighting CTPS1/2 as a potential therapeutic target for EBV-driven lymphoproliferative disorders. Collectively, our results suggest that CTPS1 and CTPS2 have partially redundant roles in EBV-transformed B cells and provide insights into EBV pathogenesis with CTPS1 deficiency.

An innovative NRF2 nano-modulator induces lung cancer ferroptosis and elicits an immunostimulatory tumor microenvironment.

Simultaneous targeting of both the tumor microenvironment and cancer cells by a single nanomedicine has not been reported to date. Here, we report the dual properties of zero-valent-iron nanoparticle (ZVI-NP) to induce cancer-specific cytotoxicity and anti-cancer immunity. Methods: Cancer-specific cytotoxicity induced by ZVI-NP was determined by MTT assay. Mitochondria functional assay, immunofluorescence staining, Western blot, RT-qPCR, and ChIP-qPCR assays were used to dissect the mechanism underlying ZVI-NP-induced ferroptotic cancer cell death. The therapeutic potential of ZVI-NP was evaluated in immunocompetent mice and humanized mice. Immune cell profiles of allografts and ex vivo cultured immune cells were examined by flow cytometry analysis, RT-qPCR assay, and immunofluorescence. Results: ZVI-NP caused mitochondria dysfunction, intracellular oxidative stress, and lipid peroxidation, leading to ferroptotic death of lung cancer cells. Degradation of NRF2 by GSK3/ß-TrCP through AMPK/mTOR activation was enhanced in such cancer-specific ferroptosis. In addition, ZVI-NP attenuated self-renewal ability of cancer and downregulated angiogenesis-related genes. Importantly, ZVI-NP augmented anti-tumor immunity by shifting pro-tumor M2 macrophages to anti-tumor M1, decreasing the population of regulatory T cells, downregulating PD-1 and CTLA4 in CD8+ T cells to potentiate their cytolytic activity against cancer cells, while attenuating PD-L1 expression in cancer cells in vitro and in tumor-bearing immunocompetent mice. In particular, ZVI-NPs preferentially accumulated in tumor and lung tissues, leading to prominent suppression of tumor growth and metastasis. Conclusions: This dual-functional nanomedicine established an effective strategy to synergistically induce ferroptotic cancer cell death and reprogram the immunosuppressive microenvironment, which highlights the potential of ZVI-NP as an advanced integrated anti-cancer strategy.