Myeloid-derived Suppressor Cells Research Articles

Immune landscape of hepatocellular carcinoma: From dysregulation of the immune responses to the potential immunotherapies.

Hepatocellular carcinoma (HCC) presents a considerable global health burden due to its late diagnosis and high morbidity. The liver's specific anatomical and physiological features expose it to various antigens, requiring precise immune regulation. To the best of our knowledge, this is the first time that a comprehensive overview of the interactions between the immune system and gut microbiota in the development of HCC, as well as the relevant therapeutic approaches are discussed. Dysregulation of immune compartments within the liver microenvironment drives HCC pathogenesis, characterized by elevated regulatory cells such as regulatory T cells (Tregs), myeloid-derived suppressor cells, and M2 macrophages as well as suppressive molecules, alongside reduced number of effector cells like T cells, natural killer cells, and M1 macrophages. Dysbiosis of gut microbiota also contributes to HCC by disrupting intestinal barrier integrity and triggering overactivated immune responses. Immunotherapy approaches, particularly immune checkpoint inhibitors, have exhibited promise in HCC management, yet adoptive cell therapy and cancer vaccination research are in the early steps with relatively less favorable outcomes. Further understanding of immune dysregulation, gut microbiota involvement, and therapeutic combination strategies are essential for advancing precision immunotherapy in HCC.

PMN-MDSC: A Culprit Behind Immunosenescence and Increased Susceptibility to Clostridioides difficile Infection During Aging

Susceptibility to pathogens in the elderly is heightened with age, largely because of immunosenescence. As an immune regulatory organ, bone marrow creates immune cells that move to other organs and tissues through the blood. Despite the significance of this process of this organ, there is limited research on changes in immune cell generation in the bone marrow and their effects on immunosenescence. In this study, the compositions of immune cells in bone marrow from young (three months) and old (24+ months) mice were compared by means of mass cytometry, with further validation obtained through the reanalysis of single-cell RNA sequencing data and cell sorting via flow cytometry. The effects of differential immune cells on immunosenescence in old mice were evaluated using the Clostridioides difficile (C. difficile) infection model. Our results showed that aged mice presented with a reduction in bone trabeculae structure, which was accompanied by a notable increase in polymorphonuclear (PMN)-myeloid-derived suppressor cell (MDSC) abundance. Through bulk-seq and reverse transcription quantitative polymerase chain reaction (RT-qPCR) analysis, we identified differential genes associated with the immune response—specifically, the Th17 cell differentiation pathway. Furthermore, the increase in exported PMN-MDSCs to the large intestine resulted in increased gut permeability and inflammatory damage to the colon following C. difficile infection. After clearing the PMN-MDSCs in old mice using the anti-Gr-1 antibody, the symptoms induced by C. difficile were significantly relieved, as evidenced by an inhibited IL-17 pathway in the colon and reduced gut permeability. In conclusion, aging increases the number of PMN-MDSCs in both the generated bone marrow and the outputted intestine, which contributes to susceptibility to C. difficile infection. This study provides a novel target for anti-aging therapy for immunosenescence, which is beneficial for improving immune function in elders.

The Complex Tumor Microenvironment in Ovarian Cancer: Therapeutic Challenges and Opportunities.

The tumor microenvironment (TME) in ovarian cancer (OC) has much greater complexity than previously understood. In response to aggressive pro-angiogenic stimulus, blood vessels form rapidly and are dysfunctional, resulting in poor perfusion, tissue hypoxia, and leakiness, which leads to increased interstitial fluid pressure (IFP). Decreased perfusion and high IFP significantly inhibit the uptake of therapies into the tumor. Within the TME, there are numerous inhibitor cells, such as myeloid-derived suppressor cells (MDSCs), tumor association macrophages (TAMs), regulatory T cells (Tregs), and cancer-associated fibroblasts (CAFs) that secrete high numbers of immunosuppressive cytokines. This immunosuppressive environment is thought to contribute to the lack of success of immunotherapies such as immune checkpoint inhibitor (ICI) treatment. This review discusses the components of the TME in OC, how these characteristics impede therapeutic efficacy, and some strategies to alleviate this inhibition.

Preclinical study and parallel phase II trial evaluating antisense STAT3 oligonucleotide and checkpoint blockade for advanced pancreatic, non-small cell lung cancer and mismatch repair-deficient colorectal cancer

ObjectiveTo evaluate signal transducer and activator of transcription 3 (STAT3) inhibition we conducted a co-clinical trial testing danvatirsen, a STAT3 antisense oligonucleotide (ASO) and checkpoint inhibition in conjunction with preclinical...

Establishment of an animal model of immune-related adverse events induced by immune checkpoint inhibitors.

Immunotherapy, specifically immune checkpoint inhibitors (ICIs), has revolutionized cancer treatment. However, it can also cause immune-related adverse events (irAEs). This study aimed to develop a clinically practical animal model of irAEs using BALB/c mice. Subcutaneous tumors of mouse breast cancer 4T1 cells were generated in inbred BALB/c mice. The mice were treated with programmed death-1 (PD-1) and cytotoxic t-lymphocyte antigen 4 (CTLA-4) inhibitors once every 3 days for five consecutive administration cycles. Changes in tumor volume and body weight were recorded. Lung computed tomography (CT) scans were conducted. The liver, lungs, heart, and colon tissues of the mice were stained with hematoxylin-eosin (H&E) staining to observe inflammatory infiltration and were scored. Serum samples were collected, and enzyme-linked immunosorbent assay (ELISA) was used to detect the levels of ferritin, glutamic-pyruvic transaminase (ALT), tumor necrosis factor-α (TNF-α), interferon-gamma (IFN-γ), and interleukin-6 (IL-6). Mouse liver and lung cell suspensions were prepared, and changes in macrophages, T cells, myeloid-derived suppressor cells (MDSCs), and regulatory (Treg) cells were detected by flow cytometry. Mice treated with PD-1 and CTLA-4 inhibitors showed significant reductions in tumor volume and body weight. The tissue inflammatory scores in the experimental group were significantly higher than those in the control group. Lung CT scans of mice in the experimental group showed obvious inflammatory spots. Serum levels of ferritin, IL-6, TNF-α, IFN-γ, and ALT were significantly elevated in the experimental group. Flow cytometry analysis revealed a substantial increase in CD3+T cells, Treg cells, and macrophages in the liver and lung tissues of mice in the experimental group compared with the control group, and the change trend of MDSCs was opposite. The irAE-related animal model was successfully established in BALB/c mice using a combination of PD-1 and CTLA-4 inhibitors through multiple administrations with clinical translational value and practical. This model offers valuable insights into irAE mechanisms for further investigation.

Increase in GPIHBP1 expression in advanced stage colorectal cancer indicates poor immune surveillance.

Glycosylphosphatidylinositol (GPI)-anchored high-density lipoprotein-binding protein 1 (GPIHBP1) plays a crucial role in fatty acid metabolism, which is involved in the progression of colorectal cancer (CRC). The aim of this study was to determine the expressional variations of GPIHBP1 in CRC at different stages and to verify whether this protein affects the shaping of the immune microenvironment of cancer cells. Variations of GPIHBP1 messenger RNA (mRNA) levels were first analysed using The Cancer Genome Atlas (TCGA) database. Protein levels of GPIHBP1 in cancer nest cells, stromal cells or surrounding normal tissues from 68 patients with CRC were checked by immunohistochemistry. Infiltration of immune cells such as macrophages, myeloid-derived suppressor cells (MDSCs), CD8+ and CD56+ cells was parallelly stained in the same tissues. Ectopic GPIHBP1 expressed colonic tumour cells were transplanted into the back of mice. Tumour growth and immune cell infiltrations were also observed. Compared with those in healthy tissues, GPIHBP1 mRNA and protein levels decreased in the patients with CRC at Dukes A-B stage but gradually increased in the patients at Dukes C-D stage. GPIHBP1 in foci or stroma was positively correlated with recruited macrophages or MDSCs and negatively correlated with recruited CD8+, CD56+ or granzyme+ cells. The mice injected with GPIHBP1 overexpression cells bore large tumours. Histological analysis confirmed the infiltration of many macrophages and MDSCs but less CD8+ T or CD56+ cells. The increased expression of GPIHBP1 is involved in the progression of CRC. High GPIHBP1 level of advanced CRC indicates efficient immune evasion in tumour microenvironment.

Shengqing Jiangzhuo decoction regulates the immunosuppressive microenvironment via the STAT3 signaling pathway for the treatment of malignant ascites in HCC

IntroductionMalignant ascites is a common complication of advanced hepatocellular carcinoma (HCC) that seriously affects the quality of life and survival of patients and has poor clinical efficacy. In the early stages, the authors found that the combination of the Shengqing Jiangzhuo decoction (SQJZD)and Endostar can effectively alleviate the clinical symptoms of malignant ascites in patients with HCC and reduce the amount of malignant ascites. The purpose of this study was to investigate the mechanism of action of SQJZD in HCC-related malignant ascites. MethodsA malignant ascites BALB/c mouse model was established by the intraperitoneal inoculation of H22 cells. The mice were randomly divided into model, Endostar, and high-, medium-, and low-dose traditional Chinese medicine (TCM) combined with Endostar groups. Normal mice from the same batch were used as the normal group. The Endostar and TCM + Endostar groups were intraperitoneally injected with Endostar, whereas the model and normal groups were intraperitoneally injected with equal amounts of normal saline. Different doses of SQJZD were administered to each TCM group, and equal amounts of distilled water were administered to the normal, model, and Endostar groups. ResultsThe malignant ascites volume and body weight were higher in the model group than in the normal group. After treatment, the volume and body weight of mice with malignant ascites decreased, especially in the SQJZD combined with Endostar group. Compared with that in the normal group, the number of regulatory T cells (Tregs) in the peripheral blood and spleen of mice in the model group was significantly decreased; the number of regulatory dendritic cells (DCregs), myeloid-derived suppressor cells (MDSCs), and tumor-associated macrophages (TAMs) in the peripheral blood were not significantly changed; and the number of DCregs, MDSCs, and TAMs in the spleen was increased. Compared with those in the model group, the numbers of Tregs, DCregs, MDSCs, and TAMs in the peripheral blood increased in the Endostar or SQJZD combined with Endostar groups, whereas the numbers of Tregs, DCregs, MDSCs, and TAMs in the spleen decreased. Western blotting revealed that the percentage of p-STAT3-positive cells in the liver and spleen of mice increased in the model group, whereas the percentage of p-STAT3-positive cells in the liver and spleen decreased in mice treated with Endostar or SQJZD combined with Endostar. ConclusionsSQJZD combined with Endostar may attenuate immunosuppression and enhance the antitumor immune response by regulating the STAT3 pathway to alleviate malignant ascites in HCC.

Therapeutic and prognostic effect of disulfidptosis-related genes in lung adenocarcinoma

Disulfidptosis, a new form of cell death, may be induced by disulfide stress associated with cystine disulfide buildup, which can promote cell toxicity, leading to cell death. Nevertheless, the role of direct prognosis and the mechanism underlying the regulation of disulfidptosis-related genes (DRGs) in lung adenocarcinoma (LUAD) are still unknown. This study aimed to investigate the role of DRGs in LUAD prognosis and diagnosis through multiomics analysis. First, copy number variations (CNVs) and mutations in the 10 genes were assessed. Considering that five differentially expressed genes (DEGs) were associated with disulfidptosis, a novel DRG score that can be utilized to anticipate LUAD prognosis was developed. Next, the generated receiver operating characteristic (ROC) and survival curves demonstrated that the model had an excellent predictive quality in LUAD in both the training and validation cohorts. Meanwhile, substantial functional disparities between the high DRG group and the low DRG group were observed, and the second gap mitosis (G2M) checkpoint, E2 promoter-binding factor (E2F) targets, and myelocytomatosis (MYC) target activities were consistently higher in the high DRG group than in the low DRG group. Additionally, the T-cell dysfunction score and tumor inflammation signature (Merck18) were negatively correlated with DRGs, whereas myeloid-derived suppressor cells (MDSCs) were positively correlated with DRGs. Moreover, DRGs were negatively linked to most of the immunological checkpoints. Meanwhile, samples of low DRGs benefited more from immune checkpoint blockade (ICB). The correlation analysis between DRGs and clinical characteristics revealed increasing malignancy with increasing DRG scores. Drug sensitization experiment results indicated that sensitivity to cisplatin, vincristine, docetaxel, and gemcitabine was higher in the high DRG group than in the low DRG group. The function of model genes in LUAD was also verified using immunohistochemistry, quantitative reverse transcription-polymerase chain reaction (qRT-PCR), western blotting, 5-ethynyl-2′-deoxyuridine (EDU), and clonogenic formation.

Extracellular vesicles originating from melanoma cells promote dysregulation in haematopoiesis as a component of cancer immunoediting.

Haematopoiesis dysregulation with the presence of immature myeloid and erythroid immunosuppressive cells are key characteristics of the immune escape phase of tumour development. Here, the role of in vitro generated B16F10 tumour cell-derived extracellular vesicles (tEVs) as indirect cellular communicators, participating in tumour-induced dysregulation of haematopoiesis, was explored. The isolated tEVs displayed features of small EVs with a size range of 100-200nm, expressed the common EV markers CD63, CD9, and Alix, and had a spherical shape with a lipid bilayer membrane. Proteomic profiling revealed significant levels of angiogenic factors, particularly vascular endothelial growth factor (VEGF), osteopontin, and tissue factor, associated with the tEVs. Systemic administration of these tEVs in syngeneic mice induced splenomegaly and disrupted haematopoiesis, leading to extramedullary haematopoiesis, expansion of splenic immature erythroid progenitors, reduced bone marrow cellularity, medullary expansion of granulocytic myeloid suppressor cells, and the development of anaemia. These effects closely mirrored those observed in tumour-bearing mice and were not seen after heat inactivating the tEVs. In vitro studies demonstrated that tEVs independently induced the expansion of bone marrow granulocytic myeloid suppressor cells and B cells while reducing the frequency of cells in the erythropoietic lineage. These effects of tEVs were significantly abrogated by the blockade of VEGF or heat inactivation. Our findings underscore the important role of tEVs in dysregulating haematopoiesis during the immune escape phase of cancer immunoediting, suggesting their potential as targets for addressing immune evasion and reinstating normal hematopoietic processes.

Impact of obesity‑associated myeloid‑derived suppressor cells on cancer risk and progression (Review).

Obesity is a chronic disease caused by the accumulation of excessive adipose tissue. This disorder is characterized by chronic low‑grade inflammation, which promotes the release of proinflammatory mediators, including cytokines, chemokines and leptin. Simultaneously, chronic inflammation can predispose to cancer development, progression and metastasis. Proinflammatory molecules are involved in the recruitment of specific cell populations in the tumor microenvironment. These cell populations include myeloid‑derived suppressor cells (MDSCs), a heterogeneous, immature myeloid population with immunosuppressive abilities. Obesity‑associated MDSCs have been linked with tumor dissemination, progression and poor clinical outcomes. A comprehensive literature review was conducted to assess the impact of obesity‑associated MDSCs on cancer in both preclinical models and oncological patients with obesity. A secondary objective was to examine the key role that leptin, the most important proinflammatory mediator released by adipocytes, plays in MDSC‑driven immunosuppression Finally, an overview is provided of the different therapeutic approaches available to target MDSCs in the context of obesity‑related cancer.

Myeloid-derived suppressor cells in axial spondyloarthritis patients with different types of therapy

Myeloid-derived suppressor cells in axial spondyloarthritis patients with different types of therapy

Myeloid‑derived suppressor cells as targets of emerging therapies and nanotherapies (Review).

Breast cancer (BC) is the leading cause of cancer-related mortality among women worldwide. Immunotherapies are a promising approach in cancer treatment, particularly for aggressive forms of BC with high mortality rates. However, the current eligibility for immunotherapy remains limited to a limited fraction of patients with BC. Myeloid-derived suppressor cells (MDSCs), originating from myeloid cells, are known for their dual role in immunosuppression and tumor promotion, significantly affecting patient outcomes by fostering the formation of premetastatic niches. Consequently, targeting MDSCs has emerged as a promising avenue for further exploration in therapeutic interventions. Leveraging nanotechnology-based drug delivery systems, which excel in accumulating drugs within tumors via passive or active targeting mechanisms, are a promising strategy for the use of MDSCs in the treatment of BC. The present review discusses the immunosuppressive functions of MDSCs, their role in BC, and the diverse strategies for targeting them in cancer therapy. Additionally, the present review discusses future advancements in BC treatments focusing on MDSCs. Furthermore, it elucidates the mechanisms underlying MDSC activation, recruitment and differentiation in BC progression, highlighting the clinical characteristics that render MDSCs suitable candidates for the therapy and targeted nanotherapy of BC.

Targeting MDSC-HTR2B to Improve Immune Checkpoint Inhibitors in Breast to Brain Metastasis.

Myeloid Derived Suppressor Cells (MDSCs) support breast cancer growth via immune suppression and non-immunological mechanisms. Although 15% of patients with breast cancer will develop brain metastasis, there is scant understanding of MDSCs' contribution within the breast-to-brain metastatic microenvironment. Utilizing co-culture models mimicking a tumor-neuron-immune microenvironment and patient tissue arrays, we identified serotonergic receptor, HTR2B, on MDSCs to upregulate pNF-κB and suppress T cell proliferation, resulting in enhanced tumor growth. In vivo murine models of metastatic and intracranial breast tumors treated with FDA-approved, anti-psychotic HTR2B antagonist, clozapine, combined with immunotherapy anti-PD-1 demonstrated a significant increase in survival and increased T cell infiltration. Collectively, these findings reveal a previously unknown role of MDSC-HTR2B in breast-to-brain metastasis, suggesting a novel and immediate therapeutic approach using neurological drugs to treat patients with metastatic breast cancer.

Myelomodulatory treatments augment the therapeutic benefit of oncolytic viroimmunotherapy in murine models of malignant peripheral nerve sheath tumors.

Malignant peripheral nerve sheath tumors (MPNST) pose a significant therapeutic challenge due to high recurrence rates after surgical resection and a largely ineffective response to traditional chemotherapy. An alternative treatment strategy is oncolytic viroimmunotherapy, which can elicit a durable and systemic antitumor immune response and is Food and Drug Administration (FDA)-approved for the treatment of melanoma. Unfortunately, only a subset of patients responds completely, underscoring the need to address barriers hindering viroimmunotherapy effectiveness. Here we investigated the therapeutic utility of targeting key components of the MPNST immunosuppressive microenvironment to enhance viroimmunotherapy's antitumor efficacy in three murine models, one of which showed more immunogenic characteristics than the others. Myelomodulatory therapy with pexidartinib, a small molecule inhibitor of CSF1R tyrosine kinase, and the oncolytic herpes simplex virus T-VEC exhibited the most significant increase in median survival time in the highly immunogenic model. Additionally, targeting myeloid cells with the myelomodulatory therapy trabectedin, a small molecule activator of caspase-8 dependent apoptosis, augmented the survival benefit of T-VEC in a less immunogenic MPNST model. However, tumor regressions or shrinkages were not observed. Depletion experiments confirmed that the enhanced survival benefit relied on a T cell response. Furthermore, flow cytometry analysis following combination viroimmunotherapy revealed decreased M2 macrophages and myeloid-derived suppressor cells and increased tumor-specific gp70+ CD8 T cells within the tumor microenvironment. In summary, our findings provide compelling evidence for the potential to leverage viroimmunotherapy with myeloid cell targeting against MPNST and warrant further investigation.

MDSCs are important osteoclast precursors primed by B cells in rheumatoid arthritis

AbstractOsteoclast‐mediated bone erosion and deformation represent significant pathological features in rheumatoid arthritis (RA). Myeloid‐derived suppressor cells (MDSCs) and B cells have emerged as key contributors to the progression of RA. Nevertheless, their involvement, especially the interaction in RA osteoclastogenesis remains elusive. In this study, our results revealed a marked expansion of MDSCs in RA patients, and importantly, their abundance was positively correlated with radiographic damage evaluated by the Sharp/van der Heijde score. Notably, MDSCs derived from both RA patients and arthritic mice exhibited a heightened propensity to differentiate into osteoclasts compared with those from healthy individuals. Intriguingly, we observed that B cells from RA patients could augment the osteoclastogenic potential of MDSCs, which was also observed in arthritic mice. The impact of B cells on MDSC‐mediated osteoclastogenesis was found to be most pronounced in switched memory B cells, followed by CD21low B cells and naïve B cells. MDSCs from B‐cell‐deficient mice exhibited diminished capacity to differentiate into osteoclasts, accompanied by distinct gene expression profiles associated with osteoclastogenesis. Taken together, our findings suggested that MDSCs were important osteoclast precursors primed by B cells in RA, serving as novel therapeutic targets for the persistent disease.

The effect of exercise and disease status on mobilization of anti-tumorigenic and pro-tumorigenic immune cells in women with breast cancer.

Mobilization of certain immune cells may improve the ability of the immune system to combat tumor cells, but the effect of acute exercise on mobilizing immune cells has been sparsely investigated in cancer patients. Therefore, we examined how acute exercise influences circulating immune cells in breast cancer patients. Nineteen newly diagnosed breast cancer patients aged 36-68 performed 30 minutes of moderate-intensity exercise with a cycle ergometer. Blood samples were collected at various time points: at rest, at 15 (E15) and 30 minutes (E30) after onset of the exercise, and at 30 and 60 minutes post-exercise. We analyzed several immune cell subsets using flow cytometry. Acute exercise increased the number of total leukocytes, neutrophils, lymphocytes, monocytes, basophils, total T-cells, CD4+ T-cells, T helper (Th) 2-cells, Th 17-cells, CD8+ T-cells, CD4-CD8- T-cells, CD56+ natural killer (NK) cells, and CD14-CD16+ monocytes. Many of the changes were transient. Proportions of NK-cells and CD8+ T-cells increased, while the proportion of myeloid derived suppressor cells (MDSCs) reduced, and proportion of regulatory T-cells remained unchanged by exercise. Several associations were detected between cell mobilizations and disease state. For instance, tumor size correlated negatively with NK cell mobilization at E15, and progesterone receptor positivity correlated negatively with CD8+ T-cell mobilization. The findings show that the proportions of CD8+ T-cells and NK cells increased and the proportion of MDSCs proportion decreased in breast cancer patients after 30-minute exercise, suggesting a change in the profile of circulating immune cells towards more cytotoxic/anti-tumorigenic. The mobilization of some immune cells also appears to be related to the disease state.

Cell of origin alters myeloid-mediated immunosuppression in lung adenocarcinoma.

Solid carcinomas are often highly heterogenous cancers, arising from multiple epithelial cells of origin. Yet, how the cell of origin influences the response of the tumor microenvironment is poorly understood. Lung adenocarcinoma (LUAD) arises in the distal alveolar epithelium which is populated primarily by alveolar epithelial type I (AT1) and type II (AT2) cells. It has been previously reported that Gramd2 + AT1 cells can give rise to a histologically-defined LUAD that is distinct in pathology and transcriptomic identity from that arising from Sftpc + AT2 cells1,2. To determine how cells of origin influence the tumor immune microenvironment (TIME) landscape, we comprehensively characterized transcriptomic, molecular, and cellular states within the TIME of Gramd2 + AT1 and Sftpc + AT2-derived LUAD using KRASG12D oncogenic driver mouse models. Myeloid cells within the Gramd2 + AT1-derived LUAD TIME were increased, specifically, immunoreactive monocytes and tumor associated macrophages (TAMs). In contrast, the Sftpc + AT2 LUAD TIME was enriched for Arginase-1+ myeloid derived suppressor cells (MDSC) and TAMs expressing profiles suggestive of immunosuppressive function. Validation of immune infiltration was performed using flow cytometry, and intercellular interaction analysis between the cells of origin and major myeloid cell populations indicated that cell-type specific markers SFTPD in AT2 cells and CAV1 in AT1 cells mediated unique interactions with myeloid cells of the differential immunosuppressive states within each cell of origin mouse model. Taken together, Gramd2 + AT1-derived LUAD presents with an anti-tumor, immunoreactive TIME, while the TIME of Sftpc + AT2-derived LUAD has hallmarks of immunosuppression. This study suggests that LUAD cell of origin influences the composition and suppression status of the TIME landscape and may hold critical implications for patient response to immunotherapy.

Targeting polymorphonuclear myeloid-derived suppressor cells in the immunosuppressive tumor microenvironment for cancer immunotherapy.

Tumor-driven immune suppression is a critical mechanism by which cancer cells evade the host immune system, leading to tumor growth and metastasis. The tumor immune microenvironment contains a large population of immune-suppressing myeloid cells, which play a key role in tumor development and drug resistance to existing immunotherapy. Polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) are important components of the immunosuppressive microenvironment. Uncovering the molecular mechanisms of PMN-MDSCs and finding specific targets for PMN-MDSCs to regulate tumor immune microenvironment is the focus and challenge of current immunotherapy. In a recent issue of Nature, Wang and colleagues revealed that CD300ld on PMN-MDSCs is required for tumor-driven immune suppression(1), this provided a new target for cancer immunotherapy, The study identified CD300ld as a novel, highly conserved tumor immunosuppressive receptor. CD300ld is highly expressed specifically on PMN-MDSCs and is a key receptor in regulating the recruitment and immunosuppressant function of PMN-MDSCs. Targeting CD300ld can reshape the tumor immune microenvironment by inhibiting the recruitment and function of PMN-MDSCs, resulting in broad-spectrum anti-tumor effects. CD300ld target shows good safety, conservation, anti-tumor effectiveness, and synergism with the Programmed death-1 target, which is expected to become a new ideal target for tumor immunotherapy.

JAK inhibition enhances checkpoint blockade immunotherapy in patients with Hodgkin lymphoma.

Unleashing antitumor T cell activity by checkpoint inhibitor immunotherapy is effective in cancer patients, but clinical responses are limited. Cytokine signaling through the Janus kinase (JAK)-signal transducer and activator of transcription (STAT) pathway correlates with checkpoint immunotherapy resistance. We report a phase I clinical trial of the JAK inhibitor ruxolitinib with anti-PD-1 antibody nivolumab in Hodgkin lymphoma patients relapsed or refractory following checkpoint inhibitor immunotherapy. The combination yielded a best overall response rate of 53% (10/19). Ruxolitinib significantly reduced neutrophil-to-lymphocyte ratios and percentages of myeloid suppressor cells but increased numbers of cytokine-producing T cells. Ruxolitinib rescued the function of exhausted T cells and enhanced the efficacy of immune checkpoint blockade in preclinical solid tumor and lymphoma models. This synergy was characterized by a switch from suppressive to immunostimulatory myeloid cells, which enhanced T cell division.

Exportin 1 governs the immunosuppressive functions of myeloid-derived suppressor cells in tumors through ERK1/2 nuclear export.

Myeloid-derived suppressor cells (MDSCs) are a main driver of immunosuppression in tumors. Understanding the mechanisms that determine the development and immunosuppressive function of these cells could provide new therapeutic targets to improve antitumor immunity. Here, using preclinical murine models, we discovered that exportin 1 (XPO1) expression is upregulated in tumor MDSCs and that this upregulation is induced by IL-6-induced STAT3 activation during MDSC differentiation. XPO1 blockade transforms MDSCs into T-cell-activating neutrophil-like cells, enhancing the antitumor immune response and restraining tumor growth. Mechanistically, XPO1 inhibition leads to the nuclear entrapment of ERK1/2, resulting in the prevention of ERK1/2 phosphorylation following the IL-6-mediated activation of the MAPK signaling pathway. Similarly, XPO1 blockade in human MDSCs induces the formation of neutrophil-like cells with immunostimulatory functions. Therefore, our findings revealed a critical role for XPO1 in MDSC differentiation and suppressive functions; exploiting these new discoveries revealed new targets for reprogramming immunosuppressive MDSCs to improve cancer therapeutic responses.