IL-1β regulates a novel myeloid-derived suppressor cell subset that impairs NK cell development and function

Deciphering mechanisms of immune escape to inform immunotherapeutic strategies in multiple myeloma

Multiple myeloma is an incurable cancer characterized by the uncontrolled growth of malignant plasma cells nurtured within a permissive bone marrow microenvironment. While patients mount numerous adaptive immune responses directed against their disease, emerging data demonstrate that tumor intrinsic and extrinsic mechanisms allow myeloma cells to subvert host immunosurveillance and resist current therapeutic strategies. Myeloma downregulates antigens recognized by cellular immunity and modulates the bone marrow microenvironment to promote uncontrolled tumor proliferation, apoptotic resistance, and further hamper anti-tumor immunity. Additional resistance often develops after an initial clinical response to small molecules, immune-targeting antibodies, immune checkpoint blockade or cellular immunotherapy. Profound quantitative and qualitative dysfunction of numerous immune effector cell types that confer anti-myeloma immunity further supports myelomagenesis, disease progression and the emergence of drug resistance. Identification of tumor intrinsic and extrinsic resistance mechanisms may direct the design of rationally-designed drug combinations that prevent or overcome drug resistance to improve patient survival. Here, we summarize various mechanisms of immune escape as a means to inform novel strategies that may restore and improve host anti-myeloma immunity.

New Discovery of Myeloid-Derived Suppressor Cell's Tale on Viral Infection and COVID-19

Myeloid-derived suppressor cells (MDSCs) are generated under biological stress such as cancer, inflammatory tissue damage, and viral infection. In recent years, with occurrence of global infectious diseases, new discovery on MDSCs functions has been significantly expanded during viral infection and COVID-19. For a successful viral infection, pathogens viruses develop immune evasion strategies to avoid immune recognition. Numerous viruses induce the differentiation and expansion of MDSCs in order to suppress host immune responses including natural killer cells, antigen presenting cells, and T-cells. Moreover, MDSCs play an important role in regulation of immunopathogenesis by balancing viral infection and tissue damage. In this review article, we describe the overview of immunomodulation and genetic regulation of MDSCs during viral infection in the animal model and human studies. In addition, we include up-to-date review of role of MDSCs in SARS-CoV-2 infection and COVID-19. Finally, we discuss potential therapeutics targeting MDSCs.

Systemic Immune Modulation Alters Local Bone Regeneration in a Delayed Treatment Composite Model of Non-Union Extremity Trauma

Bone non-unions resulting from severe traumatic injuries pose significant clinical challenges, and the biological factors that drive progression towards and healing from these injuries are still not well understood. Recently, a dysregulated systemic immune response following musculoskeletal trauma has been identified as a contributing factor for poor outcomes and complications such as infections. In particular, myeloid-derived suppressor cells (MDSCs), immunosuppressive myeloid-lineage cells that expand in response to traumatic injury, have been highlighted as a potential therapeutic target to restore systemic immune homeostasis and ultimately improve functional bone regeneration. Previously, we have developed a novel immunomodulatory therapeutic strategy to deplete MDSCs using Janus gold nanoparticles that mimic the structure and function of antibodies. Here, in a preclinical delayed treatment composite injury model of bone and muscle trauma, we investigate the effects of these nanoparticles on circulating MDSCs, systemic immune profiles, and functional bone regeneration. Unexpectedly, treatment with the nanoparticles resulted in depletion of the high side scatter subset of MDSCs and an increase in the low side scatter subset of MDSCs, resulting in an overall increase in total MDSCs. This overall increase correlated with a decrease in bone volume (P = 0.057) at 6 weeks post-treatment and a significant decrease in mechanical strength at 12 weeks post-treatment compared to untreated rats. Furthermore, MDSCs correlated negatively with endpoint bone healing at multiple timepoints. Single cell RNA sequencing of circulating immune cells revealed differing gene expression of the SNAb target molecule S100A8/A9 in MDSC sub-populations, highlighting a potential need for more targeted approaches to MDSC immunomodulatory treatment following trauma. These results provide further insights on the role of systemic immune dysregulation for severe trauma outcomes in the case of non-unions and composite injuries and suggest the need for additional studies on targeted immunomodulatory interventions to enhance healing.

The dual role of neutrophils in cancer

For the past decade, the role and importance of neutrophils in cancer is being increasingly appreciated. Research has focused on the ability of cancer-related neutrophils to either support tumor growth or interfere with it, showing diverse mechanisms through which the effects of neutrophils take place. In contrast to the historic view of neutrophils as terminally differentiated cells, mounting evidence has demonstrated that neutrophils are a plastic and diverse population of cells. These dynamic and plastic abilities allow them to perform varied and sometimes opposite functions simultaneously. In this review, we summarize and detail clinical and experimental evidence for, and underlying mechanisms of, the dual impact of neutrophils' functions, both supporting and inhibiting cancer development. We first discuss the effects of various basic functions of neutrophils, namely direct cytotoxicity, secretion of reactive oxygen species (ROS), nitric oxide (NO) and proteases, NETosis, autophagy and modulation of other immune cells, on tumor growth and metastatic progression. We then describe the clinical evidence for pro- vs anti-tumor functions of neutrophils in human cancer. We believe and show that the "net" impact of neutrophils in cancer is the sum of a complex balance between contradicting effects which occur simultaneously.

Pancreatic Cancer and Cellular Senescence: Tumor Microenvironment under the Spotlight

Pancreatic ductal adenocarcinoma (PDAC) has one of the most dismal prognoses of all cancers due to its late manifestation and resistance to current therapies. Accumulating evidence has suggested that the malignant behavior of this cancer is mainly influenced by the associated strongly immunosuppressive, desmoplastic microenvironment and by the relatively low mutational burden. PDAC develops and progresses through a multi-step process. Early in tumorigenesis, cancer cells must evade the effects of cellular senescence, which slows proliferation and promotes the immune-mediated elimination of pre-malignant cells. The role of senescence as a tumor suppressor has been well-established; however, recent evidence has revealed novel pro-tumorigenic paracrine functions of senescent cells towards their microenvironment. Understanding the interactions between tumors and their microenvironment is a growing research field, with evidence having been provided that non-tumoral cells composing the tumor microenvironment (TME) influence tumor proliferation, metabolism, cell death, and therapeutic resistance. Simultaneously, cancer cells shape a tumor-supportive and immunosuppressive environment, influencing both non-tumoral neighboring and distant cells. The overall intention of this review is to provide an overview of the interplay that occurs between senescent and non-senescent cell types and to describe how such interplay may have an impact on PDAC progression. Specifically, the effects and the molecular changes occurring in non-cancerous cells during senescence, and how these may contribute to a tumor-permissive microenvironment, will be discussed. Finally, senescence targeting strategies will be briefly introduced, highlighting their potential in the treatment of PDAC.

An Immune-Related Long Noncoding RNA Signature as a Prognostic Biomarker for Human Endometrial Cancer

Background

Endometrial cancer is among the most common malignant tumors threatening the health of women. Recently, immunity and long noncoding RNA (lncRNA) have been widely examined in oncology and shown to play important roles in oncology. Here, we searched for immune-related lncRNAs as prognostic biomarkers to predict the outcome of patients with endometrial cancer.

Methods

RNA sequencing data for 575 endometrial cancer samples and immune-related genes were downloaded from The Cancer Genome Atlas (TCGA) database and gene set enrichment analysis (GSEA) gene sets, respectively. Immune-related lncRNAs showing a coexpression relationship with immune-related genes were obtained, and Cox regression analysis was performed to construct the prognostic model. Survival, independent prognostic, and clinical correlation analyses were performed to evaluate the prognostic model. Immune infiltration of endometrial cancer samples was also evaluated. Functional annotation of 12 immune-related lncRNAs was performed using GSEA software. Prognostic nomogram and survival analysis for independent prognostic risk factors were performed to evaluate the prognostic model and calculate the survival time based on the prognostic model.

Results

Twelve immune-related lncRNAs (ELN-AS1, AC103563.7, PCAT19, AF131215.5, LINC01871, AC084117.1, NRAV, SCARNA9, AL049539.1, POC1B-AS1, AC108134.4, and AC019080.5) were obtained, and a prognostic model was constructed. The survival rate in the high-risk group was significantly lower than that in the low-risk group. Patient age, pathological grade, the International Federation of Gynecology and Obstetrics (FIGO) stage, and risk status were the risk factors. The 12 immune-related lncRNAs correlated with patient age, pathological grade, and FIGO stage. Principal component analysis and functional annotation showed that the high-risk and low-risk groups separated better, and the immune status of the high-risk and low-risk groups differed. Nomogram and receiver operating characteristic (ROC) curves effectively predicted the prognosis of endometrial cancer. Additionally, age, pathological grade, FIGO stage, and risk status were all related to patient survival.

Conclusion

We identified 12 immune-related lncRNAs affecting the prognosis of endometrial cancer, which may be useful as therapeutic targets and molecular biomarkers.

Effects of Microvesicles Derived from NK Cells Stimulated with IL-1β on the Phenotype and Functional Activity of Endothelial Cells

Microvesicles (MVs) are plasma extracellular vesicles ranging from 100 (150) to 1000 nm in diameter. These are generally produced by different cells through their vital activity and are a source of various protein and non-protein molecules. It is assumed that MVs can mediate intercellular communication and modulate cell functions. The interaction between natural killer cells (NK cells) and endothelial cells underlies multiple pathological conditions. The ability of MVs derived from NK cells to influence the functional state of endothelial cells in inflammatory conditions has yet to be studied well. In this regard, we aimed to study the effects of MVs derived from NK cells of the NK-92 cell line stimulated with IL-1β on the phenotype, caspase activity, proliferation and migration of endothelial cells of the EA.hy926 cell line. Endothelial cells were cultured with MVs derived from cells of the NK-92 cell line after their stimulation with IL-1β. Using flow cytometry, we evaluated changes in the expression of endothelial cell surface molecules and endothelial cell death. We evaluated the effect of MVs derived from stimulated NK cells on the proliferative and migratory activity of endothelial cells, as well as the activation of caspase-3 and caspase-9 therein. It was established that the incubation of endothelial cells with MVs derived from cells of the NK-92 cell line stimulated with IL-1β and with MVs derived from unstimulated NK cells, leads to the decrease in the proliferative activity of endothelial cells, appearance of the pan leukocyte marker CD45 on them, caspase-3 activation and partial endothelial cell death, and reduced CD105 expression. However, compared with MVs derived from unstimulated NK cells, a more pronounced effect of MVs derived from cells of the NK-92 cell line stimulated with IL-1β was found in relation to the decrease in the endothelial cell migratory activity and the intensity of the CD54 molecule expression on them. The functional activity of MVs is therefore mediated by the conditions they are produced under, as well as their internal contents.

The role of myeloid-derived suppressor cells in lung cancer and targeted immunotherapies

INTRODUCTION

Lung cancer is the deadliest cancer in both sexes combined globally due to significant delays in diagnosis and poor survival. Despite advances in the treatment of lung cancer, the overall outcomes remain poor and traditional chemotherapy fails to provide long-term benefits for many patients. Therefore, new treatment strategies are needed to increase overall survival. Myeloid-derived suppressor cells (MDSCs) are immunosuppressive cells taking part in lung cancer, as has been described in other types of tumors. MDSCs immunosuppressive activity is mediated by arginases (ARG-1 and ARG-2), nitric oxide (NO), reactive oxygen species (ROS), peroxynitrite, PD-1/PD-L1 axis, and different cytokines. MDSCs can be a target for lung cancer immunotherapy by inducing their differentiation into mature myeloid cells, elimination, attenuation of their function, and inhibition of their accumulation.

AREAS COVERED

In this review, the immunosuppressive function of MDSCs, their role in lung cancer, and strategies to target them, which could result in increased efficacy of immunotherapy in patients with lung cancer, are discussed.

EXPERT OPINION

Identification of important mechanisms and upstream pathways involved in MDSCs functions paves the way for further preclinical and clinical lung cancer research, which could lead to the development of novel therapeutic approaches.

Interleukin-1beta triggers the expansion of circulating granulocytic myeloid-derived suppressor cell subset dependent on Erk1/2 activation

Chronic inflammation contributes to cancer development and progression. Although interleukin-1beta (IL-1β) has been observed to be associated with an general immune suppression of T cell response and the immunosuppression strongly correlates with accumulation of myeloid-derived suppressor cells (MDSCs), the relationship and mechanism between MDSCs expansion and IL-1β expression remain ambiguous. Here, we showed that the concentration of IL-1β was highly correlated with G-MDSC subset, rather than mo-MDSC subset. Recombinant IL-1β increased the percentage of G-MDSCs in the blood of tumor-bearing mice, and IL-1Ra attenuated the accumulation of G-MDSCs in the tumor-bearing mice. In addition, the IL-1β-overexpressing B16F10 cells induced higher level of G-MDSCs compared with wild-type B16F10 cells. Moreover, we found that the accumulation of G-MDSCs induced by IL-1β was dependent on the activation of extracellular signal-regulated kinases 1 and 2 (Erk1/2). Collectively, these findings show a novel role of IL-1β in G-MDSCs accumulation by activating Erk1/2, which suggests that IL-1β elimination or Erk1/2 signaling blockade could decrease G-MDSCs generation and thereby improve host immunosurveillance.

Bulk and Single-Cell Profiling of Breast Tumors Identifies TREM-1 as a Dominant Immune Suppressive Marker Associated With Poor Outcomes

Background

Triggering receptor expressed on myeloid cells (TREM)-1 is a key mediator of innate immunity previously associated with the severity of inflammatory disorders, and more recently, the inferior survival of lung and liver cancer patients. Here, we investigated the prognostic impact and immunological correlates of TREM1 expression in breast tumors.

Methods

Breast tumor microarray and RNAseq expression profiles (n=4,364 tumors) were analyzed for associations between gene expression, tumor immune subtypes, distant metastasis-free survival (DMFS) and clinical response to neoadjuvant chemotherapy (NAC). Single-cell (sc)RNAseq was performed using the 10X Genomics platform. Statistical associations were assessed by logistic regression, Cox regression, Kaplan-Meier analysis, Spearman correlation, Student’s t-test and Chi-square test.

Results

In pre-treatment biopsies, TREM1 and known TREM-1 inducible cytokines (IL1B, IL8) were discovered by a statistical ranking procedure as top genes for which high expression was associated with reduced response to NAC, but only in the context of immunologically “hot” tumors otherwise associated with a high NAC response rate. In surgical specimens, TREM1 expression varied among tumor molecular subtypes, with highest expression in the more aggressive subtypes (Basal-like, HER2-E). High TREM1 significantly and reproducibly associated with inferior distant metastasis-free survival (DMFS), independent of conventional prognostic markers. Notably, the association between high TREM1 and inferior DMFS was most prominent in the subset of immunogenic tumors that exhibited the immunologically hot phenotype and otherwise associated with superior DMFS. Further observations from bulk and single-cell RNAseq analyses indicated that TREM1 expression was significantly enriched in polymorphonuclear myeloid-derived suppressor cells (PMN-MDSCs) and M2-like macrophages, and correlated with downstream transcriptional targets of TREM-1 (IL8, IL-1B, IL6, MCP-1, SPP1, IL1RN, INHBA) which have been previously associated with pro-tumorigenic and immunosuppressive functions.

Conclusions

Together, these findings indicate that increased TREM1 expression is prognostic of inferior breast cancer outcomes and may contribute to myeloid-mediated breast cancer progression and immune suppression.

NK Cells in the Tumor Microenvironment as New Potential Players Mediating Chemotherapy Effects in Metastatic Melanoma

Until the last decade, chemotherapy was the standard treatment for metastatic cutaneous melanoma, even with poor results. The introduction of immune checkpoints inhibitors (ICIs) radically changed the outcome, increasing 5-year survival from 5% to 60%. However, there is still a large portion of unresponsive patients that would need further therapies. NK cells are skin-resident innate cytotoxic lymphocytes that recognize and kill virus-infected as well as cancer cells thanks to a balance between inhibitory and activating signals delivered by surface molecules expressed by the target. Since NK cells are equipped with cytotoxic machinery but lack of antigen restriction and needing to be primed, they are nowadays gaining attention as an alternative to T cells to be exploited in immunotherapy. However, their usage suffers of the same limitations reported for T cells, that is the loss of immunogenicity by target cells and the difficulty to penetrate and be activated in the suppressive tumor microenvironment (TME). Several evidence showed that chemotherapy used in metastatic melanoma therapy possess immunomodulatory properties that may restore NK cells functions within TME. Here, we will discuss the capability of such chemotherapeutics to: i) up-regulate melanoma cells susceptibility to NK cell-mediated killing, ii) promote NK cells infiltration within TME, iii) target other immune cell subsets that affect NK cells activities. Alongside traditional systemic melanoma chemotherapy, a new pharmacological strategy based on nanocarriers loaded with chemotherapeutics is developing. The use of nanotechnologies represents a very promising approach to improve drug tolerability and effectiveness thanks to the targeted delivery of the therapeutic molecules. Here, we will also discuss the recent developments in using nanocarriers to deliver anti-cancer drugs within the melanoma microenvironment in order to improve chemotherapeutics effects. Overall, we highlight the possibility to use standard chemotherapeutics, possibly delivered by nanosystems, to enhance NK cells anti-tumor cytotoxicity. Combined with immunotherapies targeting NK cells, this may represent a valuable alternative approach to treat those patients that do not respond to current ICIs.

Role of myeloid-derived suppressor cells in viral respiratory infections; Hints for discovering therapeutic targets for COVID-19

The expansion of myeloid-derived suppressor cells (MDSCs), known as heterogeneous population of immature myeloid cells, is enhanced during several pathological conditions such as inflammatory or viral respiratory infections. It seems that the way MDSCs behave in infection depends on the type and the virulence mechanisms of the invader pathogen, the disease stage, and the infection-related pathology. Increasing evidence showing that in correlation with the severity of the disease, MDSCs are accumulated in COVID-19 patients, in particular in those at severe stages of the disease or ICU patients, contributing to pathogenesis of SARS-CoV2 infection. Based on the involved subsets, MDSCs delay the clearance of the virus through inhibiting T-cell proliferation and responses by employing various mechanisms such as inducing the secretion of anti-inflammatory cytokines, inducible nitric oxide synthase (iNOS)-mediated hampering of IFN-γ production, or forcing arginine shortage. While the immunosuppressive characteristic of MDSCs may help to preserve the tissue homeostasis and prevent hyperinflammation at early stages of the infection, hampering of efficient immune responses proved to exert significant pathogenic effects on severe forms of COVID-19, suggesting the targeting of MDSCs as a potential intervention to reactivate T-cell immunity and thereby prevent the infection from developing into severe stages of the disease. This review tried to compile evidence on the roles of different subsets of MDSCs during viral respiratory infections, which is far from being totally understood, and introduce the promising potential of MDSCs for developing novel diagnostic and therapeutic approaches, especially against COVID-19 disease.

Benzo[a]pyrene immunogenetics and immune archetype reprogramming of lung

Overexposure to carcinogenic precursor, benzo[a]pyrene [BaP], modulates the lung immune microenvironment. The present review seeks to elucidate novel pathways behind the tumor effect of BaP in the lungs, emphasizing immunomodulatory mediators and immune cells. In this review, BaP reprograms lung immune microenvironment through modulating transforming growth factor-beta (TGF-β), programmed cell death 1 (PD-1), cytotoxic T lymphocyte antigen-4 (CTLA-4), Interleukin 12 (IL-12), indoleamine 2,3 dioxygenase (IDO), forkhead box protein P3 (FOXP3) and interferon-gamma (IFN-γ) levels. Moreover, BaP modulated lung immune cellular architecture such as dendritic cells, T cells, Tregs, macrophages, neutrophils, and myeloid-derived suppressor cells (MDSCs). All mentioned changes in immune architecture and mediators lead to the induction of lung cancer.

Myeloid-Derived Suppressor Cells: A Propitious Road to Clinic

Myeloid-derived suppressor cells (MDSC) are important regulators of immune responses in cancer. They represent a relatively stable form of pathologic activation of neutrophils and monocytes and are characterized by distinct transcriptional, biochemical, functional, and phenotypical features. The close association of MDSCs with clinical outcomes in cancer suggests that these cells can be an attractive target for therapeutic intervention. However, the complex nature of MDSC biology represents a substantial challenge for the development of selective therapies. Here, we discuss the mechanisms regulating MDSC development and fate and recent research advances that have demonstrated opportunities for therapeutic regulation of these cells. SIGNIFICANCE: MDSCs are attractive therapeutic targets because of their close association with negative clinical outcomes in cancer and established biology as potent immunosuppressive cells. However, the complex nature of MDSC biology presents a substantial challenge for therapeutic targeting. In this review, we discuss those challenges and possible solutions.

Neutrophil-suppressive activity over T-cell proliferation and fungal clearance in a murine model of Fonsecaea pedrosoi infection

Neutrophils are essential to control several fungal infections. These cells are commonly known for their pro-inflammatory activities. However, some studies have demonstrated the anti-inflammatory properties of neutrophils during certain infectious diseases, culminating in the inhibition of T cell proliferation. Chromoblastomycosis (CBM) is a deep and progressive mycosis that affects thousands of people worldwide. Although neutrophil infiltrates are observed in the lesion histopathology, the fungus can overtake the immune system response and destroy the host-infected tissue. The present study demonstrated that neutropenic animals had an increase in the IL-6 production in the spleen and liver, followed by a lower fungal burden in these organs up to 14 days of infection. Neutropenic animals also showed a lower F. pedrosoi-specific antibody production 14-days post infection and higher T-cell proliferation in the in vitro experiments after stimulation with F. pedrosoi-purified proteins. Taken together, our results suggest that the presence of regulatory neutrophils in the mouse model of F. pedrosoi infection could act favoring the spread of the fungus and the chronicity of the infection. These findings shed light on the CBM treatment, which might target neutrophil polarization as a new therapy approach to treat CBM lesions.

Tumor NLRP3-Derived IL-1β Drives the IL-6/STAT3 Axis Resulting in Sustained MDSC-Mediated Immunosuppression

Tumors evade the immune system by inducing inflammation. In melanoma, tumor-derived IL-1β drives inflammation and the expansion of highly immunosuppressive myeloid-derived suppressor cells (MDSCs). Similar in many tumors, melanoma is also linked to the downstream IL-6/STAT3 axis. In this study, we observed that both recombinant and tumor-derived IL-1β specifically induce pSTAT3(Y705), creating a tumor-autoinflammatory loop, which amplifies IL-6 signaling in the human melanoma cell line 1205Lu. To disrupt IL-1β/IL-6/STAT3 axis, we suppressed IL-1β-mediated inflammation by inhibiting the NOD-like receptor protein 3 (NLRP3) using OLT1177, a safe-in-humans specific NLRP3 oral inhibitor. In vivo, using B16F10 melanoma, OLT1177 effectively reduced tumor progression (p< 0.01); in primary tumors, OLT1177 decreased pSTAT3(Y705) by 82% (p<0.01) and II6 expression by 53% (p<0.05). Disruption of tumor-derived NLRP3, either pharmacologically or genetically, reduced STAT3 signaling in bone marrow cells. In PMN-MDSCs isolated from tumor-bearing mice treated with OLT1177, we observed significant reductions in immunosuppressive genes such as Pdcd1l1, Arg1, Il10 and Tgfb1. In conclusion, the data presented here show that the inhibition of NLRP3 reduces IL-1β induction of pSTAT3(Y705) preventing expression of immunosuppressive genes as well as activity in PMN-MDSCs.

Tumor Secretome to Adoptive Cellular Immunotherapy: Reduce Me Before I Make You My Partner

Adoptive cellular immunotherapy using chimeric antigen receptor (CAR)-modified T cells and Natural Killer (NK) cells are common immune cell sources administered to treat cancer patients. In detail, whereas CAR-T cells induce outstanding responses in a subset of hematological malignancies, responses are much more deficient in solid tumors. Moreover, NK cells have not shown remarkable results up to date. In general, immune cells present high plasticity to change their activity and phenotype depending on the stimuli they receive from molecules secreted in the tumor microenvironment (TME). Consequently, immune cells will also secrete molecules that will shape the activities of other neighboring immune and tumor cells. Specifically, NK cells can polarize to activities as diverse as angiogenic ones instead of their killer activity. In addition, tumor cell phagocytosis by macrophages, which is required to remove dying tumor cells after the attack of NK cells or CAR-T cells, can be avoided in the TME. In addition, chemotherapy or radiotherapy treatments can induce senescence in tumor cells modifying their secretome to a known as “senescence-associated secretory phenotype” (SASP) that will also impact the immune response. Whereas the SASP initially attracts immune cells to eliminate senescent tumor cells, at high numbers of senescent cells, the SASP becomes detrimental, impacting negatively in the immune response. Last, CAR-T cells are an attractive option to overcome these events. Here, we review how molecules secreted in the TME by either tumor cells or even by immune cells impact the anti-tumor activity of surrounding immune cells.

Advances of Tumorigenesis, Diagnosis at Early Stage, and Cellular Immunotherapy in Gastrointestinal Malignancies

Globally, in 2018, 4.8 million new patients have a diagnosis of gastrointestinal (GI) cancers, while 3.4 million people died of such disorders. GI malignancies are tightly relevant to 26% of the world-wide cancer incidence and occupies 35% of all cancer-associated deaths. In this article, we principally investigated molecular and cellular mechanisms of tumorigenesis in five major GI cancers occurring at esophagus, stomach, liver, pancreas, and colorectal region that illustrate high morbidity in Eastern and Western countries. Moreover, through this investigation, we not only emphasize importance of the tumor microenvironment in development and treatment of malignant tumors but also identify significance of M2PK, miRNAs, ctDNAs, circRNAs, and CTCs in early detection of GI cancers, as well as systematically evaluate contribution of personalized precision medicine including cellular immunotherapy, new antigen and vaccine therapy, and oncolytic virotherapy in treatment of GI cancers.

Targeting tumor-derived NLRP3 reduces melanoma progression by limiting MDSCs expansion

The nucleotide-binding domain, leucine-rich containing family, pyrin domain-containing-3 (NLRP3) inflammasome, an intracellular complex that regulates maturation and release of interleukin (IL)-1β, is active in biopsies of metastatic melanoma. Here, we demonstrate that NLRP3 activation in melanoma cells drives tumor progression in mice. Subsequent to NLRP3 activation in melanoma cells, IL-1β induces melanoma-associated inflammation, resulting in immunosuppression. Oral administration of a single NLRP3 inhibitor (OLT1177) reduces melanoma growth and melanoma-associated myeloid-derived suppressor cell expansion. Inhibition of the NLRP3 signaling in combination with anti–PD-1 revealed augmented efficacy compared to monotherapy. These data propose that NLRP3 is a therapeutic target for human melanoma.

Interleukin-1β (IL-1β)–mediated inflammation suppresses antitumor immunity, leading to the generation of a tumor-permissive environment, tumor growth, and progression. Here, we demonstrate that nucleotide-binding domain, leucine-rich containing family, pyrin domain-containing-3 (NLRP3) inflammasome activation in melanoma is linked to IL-1β production, inflammation, and immunosuppression. Analysis of cancer genome datasets (TCGA and GTEx) revealed greater NLRP3 and IL-1β expression in cutaneous melanoma samples (n = 469) compared to normal skin (n = 324), with a highly significant correlation between NLRP3 and IL-1β (P < 0.0001). We show the formation of the NLRP3 inflammasome in biopsies of metastatic melanoma using fluorescent resonance energy transfer analysis for NLRP3 and apoptosis-associated speck-like protein containing a CARD. In vivo, tumor-associated NLRP3/IL-1 signaling induced expansion of myeloid-derived suppressor cells (MDSCs), leading to reduced natural killer and CD8⁺ T cell activity concomitant with an increased presence of regulatory T (Treg) cells in the primary tumors. Either genetic or pharmacological inhibition of tumor-derived NLRP3 by dapansutrile (OLT1177) was sufficient to reduce MDSCs expansion and to enhance antitumor immunity, resulting in reduced tumor growth. Additionally, we observed that the combination of NLRP3 inhibition and anti–PD-1 treatment significantly increased the antitumor efficacy of the monotherapy by limiting MDSC-mediated T cell suppression and tumor progression. These data show that NLRP3 activation in melanoma cells is a protumor mechanism, which induces MDSCs expansion and immune evasion. We conclude that inhibition of NLRP3 can augment the efficacy of anti–PD-1 therapy.

Receptor Tyrosine Kinase Inhibitor Sunitinib as Novel Immunotherapy to Inhibit Myeloid-Derived Suppressor Cells for Treatment of Endometriosis

Endometriosis is a common, benign, and hormone-dependent gynaecological disorder that displays altered immunoinflammatory profiles. Myeloid-derived suppressor cells (MDSCs) suppressed immunosurveillance in endometriosis in human and mouse model. Receptor tyrosine kinase inhibitor Sunitinib can induce MDSC apoptosis and suppress the progression of cancer. However, the effects of Sunitinib on MDSCs in endometriosis and the underlying mechanism are not clear. In this study, we employed an animal study of the endometriosis model in mice for treatment of Sunitinib. After syngeneic endometrium transplantation and treatment, endometriotic lesion volume, weight, and histology were compared. Peritoneal fluid, peripheral blood, and bone marrow MDSC subsets and their molecular signaling were monitored by flow cytometry. Peritoneal cytokines were assayed by ELISA. The gene expression profiles of isolated CD11b+Ly6G+Ly6C^lo cells were studied by RNA sequencing. We found that Sunitinib significantly decreased the endometriotic lesion size and weight after 1 and 3 weeks, and decreased p-STAT3 activation in MDSCs after 1 week of treatment. In the first week, Sunitinib specifically increased the G-MDSC population in peritoneal fluid but the isolated CD11b+Ly6G+Ly6C^lo MDSCs after Sunitinib treatment were presented as mature polynuclear MDSCs, while the control group had immature mononuclear MDSCs. Importantly, we found Sunitinib differentially suppressed gene expressions of immunosuppressive function and differentiation in peritoneal G-MDSCs. Apelin signaling pathway associated genes and inflammation related genes were upregulated, and amino acid metabolism regulator genes were downregulated in bone marrow G-MDSCs. For endometriotic lesions, the PPARG gene governing glucose metabolism and fatty acid storage, which is important for the development of endometriosis was upregulated. In conclusion, Sunitinib inhibited endometriotic lesions, by promoting peritoneal fluid MDSCs maturation and inhibiting the immunosuppressive function. These findings suggest that Sunitinib changed the immune microenvironment and inhibited the development of endometriosis, which has potential therapeutic effects as novel immunotherapy to promote MDSCs maturation, differentiation, and metabolism for the treatment of endometriosis.

Neutrophils in the era of immune checkpoint blockade

The immune checkpoint blockade-based immunotherapies are revolutionizing cancer management. Tumor-associated neutrophils (TANs) were recently highlighted to have a pivotal role in modulating the tumor microenvironment and the antitumor immune response. However, these cells were largely ignored during the development of therapies based on programmed cell death receptor or ligand-1 and cytotoxic T lymphocyte antigen-4 immune checkpoint inhibitors (ICIs). Latest evidences of neutrophil functional diversity in tumor raised many questions and suggest that targeting these cells can offer new treatment opportunities in the context of ICI development. Here, we summarized key information on TAN origin, function, and plasticity that should be considered when developing ICIs and provide a detailed review of the ongoing clinical trials that combine ICIs and a second compound that might affect or be affected by TANs. This review article synthetizes important notions from the literature demonstrating that: (1) Cancer development associates with a profound alteration of neutrophil biogenesis and function that can predict and interfere with the response to ICIs, (2) Neutrophil infiltration in tumor is associated with key features of resistance to ICIs, and (3) TANs play an important role in resistance to antiangiogenic drugs reducing their clinical benefit when used in combination with ICIs. Finally, exploring the clinical/translational aspects of neutrophil impact on the response to ICIs offers the opportunity to propose new translational research avenues to better understand TAN biology and treat patients.

Targeting Myeloid-Derived Suppressor Cells for Premetastatic Niche Disruption After Tumor Resection

Surgical resection is a common therapeutic option for primary solid tumors. However, high cancer recurrence and metastatic rates after resection are the main cause of cancer related mortalities. This implies the existence of a "fertile soil" following surgery that facilitates colonization by circulating cancer cells. Myeloid-derived suppressor cells (MDSCs) are essential for premetastatic niche formation, and may persist in distant organs for up to 2 weeks after surgery. These postsurgical persistent lung MDSCs exhibit stronger immunosuppression compared with presurgical MDSCs, suggesting that surgery enhances MDSC function. Surgical stress and trauma trigger the secretion of systemic inflammatory cytokines, which enhance MDSC mobilization and proliferation. Additionally, damage associated molecular patterns (DAMPs) directly activate MDSCs through pattern recognition receptor-mediated signals. Surgery also increases vascular permeability, induces an increase in lysyl oxidase and extracellular matrix remodeling in lungs, that enhances MDSC mobilization. Postsurgical therapies that inhibit the induction of premetastatic niches by MDSCs promote the long-term survival of patients. Cyclooxygenase-2 inhibitors and β-blockade, or their combination, may minimize the impact of surgical stress on MDSCs. Anti-DAMPs and associated inflammatory signaling inhibitors also are potential therapies. Existing therapies under tumor-bearing conditions, such as MDSCs depletion with low-dose chemotherapy or tyrosine kinase inhibitors, MDSCs differentiation using all-trans retinoic acid, and STAT3 inhibition merit clinical evaluation during the perioperative period. In addition, combining low-dose epigenetic drugs with chemokine receptors, reversing immunosuppression through the Enhanced Recovery After Surgery protocol, repairing vascular leakage, or inhibiting extracellular matrix remodeling also may enhance the long-term survival of curative resection patients.

Myeloid derived suppressor cells and the release of micro-metastases from dormancy

Metastasis is the primary cause of cancer mortality and an improved understanding of its pathology is critical to the development of novel therapeutic approaches. Mechanism-based therapeutic strategies require insight into the timing of tumor cell dissemination, seeding of distant organs, formation of occult lesions and critically, their release from dormancy. Due to imaging limitations, primary tumors can only be detected when they reach a relatively large size (e.g. > 1 cm³), which, based on our understanding of tumor evolution, occurs approximately 10 years and about 30 doubling times following tumor initiation. Genomic profiling of paired primary tumors and metastases has suggested that tumor seeding at secondary sites occurs early during tumor progression and frequently, years prior to clinical diagnosis. Following seeding, tumor cells may enter into and remain in a dormant state, and if they survive and are released from dormancy, they can proliferate into an overt lesion. The timeline of tumor initiation and metastatic dormancy is regulated by tumor interactions with its microenvironment, angiogenesis, and tumor-specific cytotoxic T-lymphocyte (CTL) responses. Therefore, a better understanding of the cellular interactions responsible for immune evasion and/or tumor cell release from dormancy would facilitate the development of therapeutics targeted against this critical part of tumor progression. The immunosuppressive mechanisms mediated by myeloid-derived suppressor cells (MDSCs) contribute to tumor progression and, we posit, promote tumor cell escape from CTL-associated dormancy. Thus, while clinical and translational research has demonstrated a role for MDSCs in facilitating tumor progression and metastasis through tumor escape from adoptive and innate immune responses (T-, natural killer and B-cell responses), few studies have considered the role of MDSCs in tumor release from dormancy. In this review, we discuss MDSC expansion, driven by tumor burden associated growth factor secretion and their role in tumor cell escape from dormancy, resulting in manifest metastases. Thus, the therapeutic strategies to inhibit MDSC expansion and function may provide an approach to delay metastatic relapse and prolong the survival of patients with advanced malignancies.

Natural Killer Cell Interactions With Myeloid Derived Suppressor Cells in the Tumor Microenvironment and Implications for Cancer Immunotherapy

The tumor microenvironment (TME) is a complex and heterogeneous environment composed of cancer cells, tumor stroma, a mixture of tissue-resident and infiltrating immune cells, secreted factors, and extracellular matrix proteins. Natural killer (NK) cells play a vital role in fighting tumors, but chronic stimulation and immunosuppression in the TME lead to NK cell exhaustion and limited antitumor functions. Myeloid-derived suppressor cells (MDSCs) are a heterogeneous group of myeloid cells with potent immunosuppressive activity that gradually accumulate in tumor tissues. MDSCs interact with innate and adaptive immune cells and play a crucial role in negatively regulating the immune response to tumors. This review discusses MDSC-mediated NK cell regulation within the TME, focusing on critical cellular and molecular interactions. We review current strategies that target MDSC-mediated immunosuppression to enhance NK cell cytotoxic antitumor activity. We also speculate on how NK cell-based antitumor immunotherapy could be improved.

Tumor-related stress regulates functional plasticity of MDSCs

Myeloid-derived suppressor cells (MDSCs) impair protective anti-tumor immunity and remain major obstacles that stymie the effectiveness of promising cancer therapies. Diverse tumor-derived stressors galvanize the differentiation, intra-tumoral expansion, and immunomodulatory function of MDSCs. These tumor-associated 'axes of stress' underwrite the immunosuppressive programming of MDSCs in cancer and contribute to the phenotypic/functional heterogeneity that characterize tumor-MDSCs. This review discusses various tumor-associated axes of stress that direct MDSC development, accumulation, and immunosuppressive function, as well as current strategies aimed at overcoming the detrimental impact of MDSCs in cancer. To better understand the constellation of signals directing MDSC biology, we herein summarize the pivotal roles, signaling mediators, and effects of reactive oxygen/nitrogen species-related stress, chronic inflammatory stress, hypoxia-linked stress, endoplasmic reticulum stress, metabolic stress, and therapy-associated stress on MDSCs. Although therapeutic targeting of these processes remains mostly pre-clinical, intercepting signaling through the axes of stress could overcome MDSC-related immune suppression in tumor-bearing hosts.

Osteoclasts in Tumor Biology: Metastasis and Epithelial-Mesenchymal-Myeloid Transition

Osteoclast is a specialized cell that originates from monocytic lineage, communicates closely with osteoblasts under physiological conditions, participates in bone modeling and re-modeling, contributes to calcium homeostasis and osteoimmunity. In pathological conditions, it is involved in many tumors such as giant cell bone tumor (osteoclastoma), aneurysmal bone cyst, osteosarcoma, and metastatic cancers, and it usually causes local spread and progression of the tumor, working against the host. Since osteoclasts play an active role in primary bone tumors and bone metastases, the use of anti-osteoclastic agents significantly reduces the mortality and morbidity rates of patients by preventing the progression and local spread of tumors. Osteoclasts also accompany undifferentiated carcinomas of many organs, especially pancreas, thyroid, bladder and ovary. Undifferentiated carcinomas rich in osteoclasts have osteoclastoma-like histology. In these organs, osteoclastoma-like histology may accompany epithelial carcinomas, and de novo, benign and borderline tumors. Mature and immature myeloid cells, including osteoclasts, play an active role in the tumor progression in primary and metastatic tumor microenvironment, in epithelial-mesenchymal transition (EMT), mesenchymal-epithelial-transition (MET), and cancer stem cell formation. Additionally, they are the most suitable candidates for cancer cells in cell fusion due to their evolutionary fusion capabilities. Myeloid features and markers (CD163, CD33, CD68 etc.) can be seen in metastatic cancer cells. Consequently, they provide metastatic cancer cells with motility, margination, transmigration, chemotaxis, phagocytosis, angiogenesis, matrix degradation, and resistance to chemotherapy. For these reasons, we think that the concept of Epithelial-Mesencyhmal-Myeloid-Transition (EMMT) will be more accurate than EMT for cancer cells with myeloid properties.

Increased Serum Levels of Soluble TNF-α Receptor Is Associated With ICU Mortality in COVID-19 Patients

Background

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) that causes coronavirus disease 2019 (COVID-19) has infected over 112M patients and resulted in almost 2.5M deaths worldwide. The major clinical feature of severe COVID-19 patients requiring ventilation is acute respiratory distress syndrome (ARDS) possibly associated with a cytokine storm.

Objectives

To elucidate serum levels of TNF-α and soluble TNF-Receptor 1 (sTNFR1) in patients with severe and mild COVID-19 disease as determinants of disease severity.

Methods

We determined serum TNF-α and sTNFR1 concentrations in 46 patients with laboratory-confirmed COVID-19 (17 patients with severe disease within the intensive care unit [ICU] and 29 non-severe, non-ICU patients) and 15 healthy controls upon admission using ELISA. Subjects were recruited between March-May 2020 at the Masih Daneshvari Hospital Tehran, Iran.

Results

Serum levels of sTNFRI were significantly higher in ICU patients (P<0.0001) and non-ICU patients (P=0.0342) compared with healthy subjects. Serum sTNFR1 were significantly higher in ICU patients than in non-ICU patients (P<0.0001). Serum TNF-α levels were greater in ICU and non-ICU patients than in the healthy subjects group (p<0.0001). The sTNFRI concentration in ICU (r=0.79, p=0.0002) and non-ICU (r=0.42, p=0.02) patients positively correlated with age although serum sTNFRI levels in ICU patients were significantly higher than in older healthy subjects. The sTNFRI concentration in ICU patients negatively correlated with ESR.

Conclusions

The study demonstrates higher sTNFRI in ICU patients with severe COVID-19 disease and this be a biomarker of disease severity and mortality. Future studies should examine whether lower levels of systemic sTNFR1 at admission may indicate a better disease outcome.

Therapeutic Approaches Targeting the Natural Killer-Myeloid Cell Axis in the Tumor Microenvironment

Immunotherapy has transformed cancer treatment by promoting durable clinical responses in a proportion of patients; however, treatment still fails in many patients. Innate immune cells play a key role in the response to immunotherapy. Crosstalk between innate and adaptive immune systems drives T-cell activation but also limits immunotherapy response, as myeloid cells are commonly associated with resistance. Hence, innate cells have both negative and positive effects within the tumor microenvironment (TME), and despite investment in early clinical trials targeting innate cells, they have seen limited success. Suppressive myeloid cells facilitate metastasis and immunotherapy resistance through TME remodeling and inhibition of adaptive immune cells. Natural killer (NK) cells, in contrast, secrete inflammatory cytokines and directly kill transformed cells, playing a key immunosurveillance role in early tumor development. Myeloid and NK cells show reciprocal crosstalk, influencing myeloid cell functional status or antigen presentation and NK effector function, respectively. Crosstalk between myeloid cells and the NK immune network in the TME is especially important in the context of therapeutic intervention. Here we discuss how myeloid and NK cell interactions shape anti-tumor responses by influencing an immunosuppressive TME and how this may influence outcomes of treatment strategies involving drugs that target myeloid and NK cells.

Combined Effects of Myeloid Cells in the Neuroblastoma Tumor Microenvironment

Despite multimodal treatment, survival chances for high-risk neuroblastoma patients remain poor. Immunotherapeutic approaches focusing on the activation and/or modification of host immunity for eliminating tumor cells, such as chimeric antigen receptor (CAR) T cells, are currently in development, however clinical trials have failed to reproduce the preclinical results. The tumor microenvironment is emerging as a major contributor to immune suppression and tumor evasion in solid cancers and thus has to be overcome for therapies relying on a functional immune response. Among the cellular components of the neuroblastoma tumor microenvironment, suppressive myeloid cells have been described as key players in inhibition of antitumor immune responses and have been shown to positively correlate with more aggressive disease, resistance to treatments, and overall poor prognosis. This review article summarizes how neuroblastoma-driven inflammation induces suppressive myeloid cells in the tumor microenvironment and how they in turn sustain the tumor niche through suppressor functions, such as nutrient depletion and generation of oxidative stress. Numerous preclinical studies have suggested a range of drug and cellular therapy approaches to overcome myeloid-derived suppression in neuroblastoma that warrant evaluation in future clinical studies.

Myeloid-Derived Suppressor Cells: Facilitators of Cancer and Obesity-Induced Cancer

Immature myeloid cells at varied stages of differentiation, known as myeloid-derived suppressor cells (MDSC), are present in virtually all cancer patients. MDSC are profoundly immune-suppressive cells that impair adaptive and innate antitumor immunity and promote tumor progression through nonimmune mechanisms. Their widespread presence combined with their multitude of protumor activities makes MDSC a major obstacle to cancer immunotherapies. MDSC are derived from progenitor cells in the bone marrow and traffic through the blood to infiltrate solid tumors. Their accumulation and suppressive potency are driven by multiple tumor- and host-secreted proinflammatory factors and adrenergic signals that act via diverse but sometimes overlapping transcriptional pathways. MDSC also accumulate in response to the chronic inflammation and lipid deposition characteristic of obesity and contribute to the more rapid progression of cancers in obese individuals. This article summarizes the key aspects of tumor-induced MDSC with a focus on recent progress in the MDSC field.

Interaction Between MDSC and NK Cells in Solid and Hematological Malignancies: Impact on HSCT

Myeloid derived suppressor cells (MDSC) are heterogeneous populations that through the release of soluble factors and/or by cell-to-cell interactions suppress both innate and adaptive immune effector cells. In pathological conditions, characterized by the presence of inflammation, a partial block in the differentiation potential of myeloid precursors causes an accumulation of these immunosuppressive cell subsets both in peripheral blood and in tissues. On the contrary, NK cells represent a major player of innate immunity able to counteract tumor growth. The anti-tumor activity of NK cells is primarily related to their cytolytic potential and to the secretion of soluble factors or cytokines that may act on tumors either directly or indirectly upon the recruitment of other cell types. NK cells have been shown to play a fundamental role in haploidentical hemopoietic stem cell transplantation (HSCT), for the therapy of high-risk leukemias. A deeper analysis of MDSC functional effects demonstrated that these cells are capable, through several mechanisms, to reduce the potent GvL activity exerted by NK cells. It is conceivable that, in this transplantation setting, the MDSC-removal or -inactivation may represent a promising strategy to restore the anti-leukemia effect mediated by NK cells. Thus, a better knowledge of the cellular interactions occurring in the tumor microenvironment could promote the development of novel therapeutic strategies for the treatment of solid and hematological malignances.

Recent Advancements in the Mechanisms Underlying Resistance to PD-1/PD-L1 Blockade Immunotherapy

Simple Summary

Immune checkpoint blockade targeting PD-1/PD-L1 has a promising therapeutic efficacy in different tumors, but a significant percentage of patients cannot benefit from this therapy due to primary and acquired resistance during treatment. This review summarizes the recent findings of PD-L1 role in resistance to therapies through the PD-1/PD-L1 pathway and other correlating signaling pathways. A special focus will be given to the key mechanisms underlying resistance to the PD-1/PD-L1 blockade in cancer immunotherapy. Furthermore, we also discuss the promising combination of therapeutic strategies for patients resistant to the PD-1/PD-L1 blockade in order to enhance the efficacy of immune checkpoint inhibitors.

Abstract

Release of immunoreactive negative regulatory factors such as immune checkpoint limits antitumor responses. PD-L1 as a significant immunosuppressive factor has been involved in resistance to therapies such as chemotherapy and target therapy in various cancers. Via interacting with PD-1, PD-L1 can regulate other factors or lead to immune evasion of cancer cells. Besides, immune checkpoint blockade targeting PD-1/PD-L1 has promising therapeutic efficacy in the different tumors, but a significant percentage of patients cannot benefit from this therapy due to primary and acquired resistance during treatment. In this review, we described the utility of PD-L1 expression levels for predicting poor prognosis in some tumors and present evidence for a role of PD-L1 in resistance to therapies through PD-1/PD-L1 pathway and other correlating signaling pathways. Afterwards, we elaborate the key mechanisms underlying resistance to PD-1/PD-L1 blockade in cancer immunotherapy. Furthermore, promising combination of therapeutic strategies for patients resistant to PD-1/PD-L1 blockade therapy or other therapies associated with PD-L1 expression was also summarized.

Cytokines Orchestrating the Natural Killer-Myeloid Cell Crosstalk in the Tumor Microenvironment: Implications for Natural Killer Cell-Based Cancer Immunotherapy

Natural killer (NK) cells are endowed with germline-encoded receptors that enable them to detect and kill malignant cells without prior priming. Over the years, overwhelming evidence has identified an essential role for NK cells in tumor immune surveillance. More recently, clinical trials have also highlighted their potential in therapeutic settings. Yet, data show that NK cells can be dysregulated within the tumor microenvironment (TME), rendering them ineffective in eradicating the cancer cells. This has been attributed to immune suppressive factors, including the tumor cells per se, stromal cells, regulatory T cells, and soluble factors such as reactive oxygen species and cytokines. However, the TME also hosts myeloid cells such as dendritic cells, macrophages, neutrophils, and myeloid-derived suppressor cells that influence NK cell function. Although the NK-myeloid cell crosstalk can promote anti-tumor responses, myeloid cells in the TME often dysregulate NK cells via direct cell-to-cell interactions down-regulating key NK cell receptors, depletion of nutrients and growth factors required for NK cell growth, and secretion of metabolites, chemokines and cytokines that ultimately alter NK cell trafficking, survival, and cytotoxicity. Here, we review the complex functions of myeloid-derived cytokines in both supporting and suppressing NK cells in the TME and how NK cell-derived cytokines can influence myeloid subsets. We discuss challenges related to these interactions in unleashing the full potential of endogenous and adoptively infused NK cells. Finally, we present strategies aiming at improving NK cell-based cancer immunotherapies via pathways that are involved in the NK-myeloid cell crosstalk in the TME.

Therapeutic Strategies for Targeting IL-1 in Cancer

Since its discovery, interleukin-1 has been extensively studied in a wide range of medical fields. Besides carrying out vital physiological functions, it has been implicated with a pivotal role in the progression and spreading of different cancer entities. During the last years, several clinical trials have been conducted, shedding light on the role of IL-1 blocking agents for the treatment of cancer. Additionally, recent developments in the field of immuno-oncology have implicated IL-1-induced signaling cascades as a major driver of severe chimeric antigen receptor T cell-associated toxicities such as cytokine release syndrome and immune effector cell-associated neurotoxicity. In this review, we summarize current clinical trials investigating the role of IL-1 blockade in cancer treatment and elaborate the proposed mechanism of these innovative treatment approaches. Additionally, we highlight cutting-edge developments utilizing IL-1 blocking agents to enhance the safety and efficacy of adoptive T cell therapy.

Effects of in IL-1B/IL-1RN variants on the susceptibility to head and neck cancer in a chinese Han population

Background

The study aimed to evaluate the relationship of IL-1B/IL-1RN polymorphisms to the predisposition of head and neck cancer (HNC) in a Chinese Han population.

Methods

Nine single-nucleotide polymorphisms (SNPs) in IL-1B/IL-1RN were genotyped based on Agena MassARRAY platform. Logistic regression models were used to analyze the genetic association between these SNPs and HNC risk by calculating odds ratios (ORs) and 95% confidence intervals (CI). Haplotype analysis were performed using Haploview program and logistic regression model.

Results

The genetic association between rs1143643 in IL-1B and the higher risk of HNC was found (OR = 1.23, 95% CI 1.04–1.46) in the overall. IL-1RN rs17042888 was related to a reduced risk of HNC in the subjects aged > 46 years (OR = 0.70, 95% CI: 0.50–0.98) and in females (OR = 0.71, 95% CI 0.52–0.98), while rs1143643 increased the predisposition of HNC among females (OR = 1.76, 95% CI 1.13–2.74). Furthermore, rs1143643 had an increased susceptibility to thyroid carcinoma (OR = 1.61, 95% CI 1.10–2.34). Moreover, compared with stage I–II, the frequency of IL-1RN rs452204-AG genotype was lower in patients with stage III–IV.

Conclusions

IL-1B (rs1143643) and IL-1RN (rs17042888 and rs452204) polymorphisms might be related to the individual susceptibility of HNC in the Chinese Han population. These results might help to improve the understanding of IL-1B and IL-1RN genes in the occurrence of HNC.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12935-021-01750-0.

The Functional Crosstalk between Myeloid-Derived Suppressor Cells and Regulatory T Cells within the Immunosuppressive Tumor Microenvironment

Simple Summary

Immunotherapy improved the therapeutic landscape for patients with advanced cancer diseases. However, many patients do not benefit from immunotherapy. The bidirectional crosstalk between myeloid-derived suppressor cells (MDSC) and regulatory T cells (Treg) contributes to immune evasion, limiting the success of immunotherapy by checkpoint inhibitors. This review aims to outline the current knowledge of the role and the immunosuppressive properties of MDSC and Treg within the tumor microenvironment (TME). Furthermore, we will discuss the importance of the functional crosstalk between MDSC and Treg for immunosuppression, issuing particularly the role of cell adhesion molecules. Lastly, we will depict the impact of this interaction for cancer research and discuss several strategies aimed to target these pathways for tumor therapy.

Abstract

Immune checkpoint inhibitors (ICI) have led to profound and durable tumor regression in some patients with metastatic cancer diseases. However, many patients still do not derive benefit from immunotherapy. Here, the accumulation of immunosuppressive cell populations within the tumor microenvironment (TME), such as myeloid-derived suppressor cells (MDSC), tumor-associated macrophages (TAM), and regulatory T cells (Treg), contributes to the development of immune resistance. MDSC and Treg expand systematically in tumor patients and inhibit T cell activation and T effector cell function. Numerous studies have shown that the immunosuppressive mechanisms exerted by those inhibitory cell populations comprise soluble immunomodulatory mediators and receptor interactions. The latter are also required for the crosstalk of MDSC and Treg, raising questions about the relevance of cell–cell contacts for the establishment of their inhibitory properties. This review aims to outline the current knowledge on the crosstalk between these two cell populations, issuing particularly the potential role of cell adhesion molecules. In this regard, we further discuss the relevance of β2 integrins, which are essential for the differentiation and function of leukocytes as well as for MDSC–Treg interaction. Lastly, we aim to describe the impact of such bidirectional crosstalk for basic and applied cancer research and discuss how the targeting of these pathways might pave the way for future approaches in immunotherapy.

Cancer Cells Resistance Shaping by Tumor Infiltrating Myeloid Cells

Interactions between malignant cells and neighboring stromal and immune cells profoundly shape cancer progression. New forms of therapies targeting these cells have revolutionized the treatment of cancer. However, in order to specifically address each population, it was essential to identify and understand their individual roles in interaction between malignant cells, and the formation of the tumor microenvironment (TME). In this review, we focus on the myeloid cell compartment, a prominent, and heterogeneous group populating TME, which can initially exert an anti-tumoral effect, but with time actively participate in disease progression. Macrophages, dendritic cells, neutrophils, myeloid-derived suppressor cells, mast cells, eosinophils, and basophils act alone or in concert to shape tumor cells resistance through cellular interaction and/or release of soluble factors favoring survival, proliferation, and migration of tumor cells, but also immune-escape and therapy resistance.

Interaction Between MDSC and NK Cells in Solid and Hematological Malignancies: Impact on HSCT

Myeloid derived suppressor cells (MDSC) are heterogeneous populations that through the release of soluble factors and/or by cell-to-cell interactions suppress both innate and adaptive immune effector cells. In pathological conditions, characterized by the presence of inflammation, a partial block in the differentiation potential of myeloid precursors causes an accumulation of these immunosuppressive cell subsets both in peripheral blood and in tissues. On the contrary, NK cells represent a major player of innate immunity able to counteract tumor growth. The anti-tumor activity of NK cells is primarily related to their cytolytic potential and to the secretion of soluble factors or cytokines that may act on tumors either directly or indirectly upon the recruitment of other cell types. NK cells have been shown to play a fundamental role in haploidentical hemopoietic stem cell transplantation (HSCT), for the therapy of high-risk leukemias. A deeper analysis of MDSC functional effects demonstrated that these cells are capable, through several mechanisms, to reduce the potent GvL activity exerted by NK cells. It is conceivable that, in this transplantation setting, the MDSC-removal or -inactivation may represent a promising strategy to restore the anti-leukemia effect mediated by NK cells. Thus, a better knowledge of the cellular interactions occurring in the tumor microenvironment could promote the development of novel therapeutic strategies for the treatment of solid and hematological malignances.

Prognostic Role of Monocytic Myeloid-Derived Suppressor Cells in Advanced Non-Small-Cell Lung Cancer: Relation to Different Hematologic Indices

METHODS

We recruited 40 cases of advanced NSCLC, stages III and IV, aged > 18-<70 years old, and eligible to receive chemotherapy with or without radiotherapy, along with 20 healthy controls of comparable age and sex; after diagnosis and staging of patients, blood samples were collected for flow cytometric detection of Mo-MDSCs.

RESULTS

Significant accumulation of Mo-MDSCs in patients compared to their controls (p < 0.0001). Furthermore, these cells accumulated significantly in stage IV compared to stage III (p = 0.006) and correlated negatively with overall survival (r = -0.471, p = 0.002), lymphocyte to monocyte ratio (r = -0.446, p = 0.004), and mean platelet volume to platelet count ratio (MPV/PC) (r = -0.464, p = 0.003), patients with Mo-MDSCs < 13% had significantly better survival than those with Mo-MDSCs ≥ 13% (p = 0.041).

CONCLUSION

Mo-MDSCs represent one of the key mechanisms in the immunosuppressive tumor microenvironment (TME) to play major roles not only in the carcinogenesis of lung cancer but also in disease progression and prognosis and, in addition, predict the efficacy of immune checkpoint inhibitors; our results provided some support to target Mo-MDSCs and needed to be augmented by further studies.

Extracellular vesicles released by myeloid-derived suppressor cells from pregnant women modulate adaptive immune responses

Immunological pregnancy complications are a main challenge in reproductive medicine. Mechanisms regulating the adaptation of the maternal immune system to pregnancy are incompletely understood and therapeutic options limited. Myeloid derived suppressor cells (MDSC) are immune-modulatory cells expanding during healthy pregnancy and seem to play a crucial role for maternal-fetal tolerance. Recent studies showed that exosomes produced by MDSC have immune-modulatory effects corresponding to their parental cells under different pathological conditions. Here, we investigated immunological effects of exosomes of GR-MDSC during pregnancy. Isolated GR-MDSC exosomes from peripheral blood of pregnant women were tested for functionality in different in vitro assays. We show that GR-MDSC exosomes exhibited profound immune-modulatory effects such as suppression of T-cell proliferation, T helper 2 (Th2)-cell polarization, induction of regulatory T-cells and inhibition of lymphocyte cytotoxicity. Our results confirm that MDSC-derived exosomes functionally correspond to their parental cells and identify them as an interesting therapeutic target for immunological pregnancy complications.

The CCR2/MCP-1 Chemokine Pathway and Lung Adenocarcinoma

Host anti-tumor immunity can be hindered by various mechanisms present within the tumor microenvironment, including the actions of myeloid-derived suppressor cells (MDSCs). We investigated the role of the CCR2/MCP-1 pathway in MDSC-associated tumor progression in murine lung cancer models. Phenotypic profiling revealed maximal expression of CCR2 by tumor-resident MDSCs, and MCP-1 by transplanted TC1 tumor cells, respectively. Use of CCR2-knockout (CCR2-KO) mice showed dependence of tumor growth on CCR2 signaling. Tumors in CCR2-KO mice had fewer CCR2low MDSCs, CD4 T cells and Tregs than WT mice, and increased infiltration by CD8 T cells producing IFN-γ and granzyme-B. Effects were MDSC specific, since WT and CCR2-KO conventional T (Tcon) cells had comparable proliferation and production of inflammatory cytokines, and suppressive functions of WT and CCR2-KO Foxp3+ Treg cells were also similar. We used a thioglycolate-induced peritonitis model to demonstrate a role for CCR2/MCP-1 in trafficking of CCR2+ cells to an inflammatory site, and showed the ability of a CCR2 antagonist to inhibit such trafficking. Use of this CCR2 antagonist promoted anti-tumor immunity and limited tumor growth. In summary, tumor cells are the prime source of MCP-1 that promotes MDSC recruitment, and our genetic and pharmacologic data demonstrate that CCR2 targeting may be an important component of cancer immunotherapy.

Brassica Bioactives Could Ameliorate the Chronic Inflammatory Condition of Endometriosis

Endometriosis is a chronic, inflammatory, hormone-dependent disease characterized by histological lesions produced by the presence of endometrial tissue outside the uterine cavity. Despite the fact that an estimated 176 million women are affected worldwide by this gynecological disorder, risk factors that cause endometriosis have not been properly defined and current treatments are not efficient. Although the interaction between diet and human health has been the focus of many studies, little information about the correlation of foods and their bioactive derivates with endometriosis is available. In this framework, Brassica crops have emerged as potential candidates for ameliorating the chronic inflammatory condition of endometriosis, due to their abundant content of health-promoting compounds such as glucosinolates and their hydrolysis products, isothiocyanates. Several inflammation-related signaling pathways have been included among the known targets of isothiocyanates, but those involving aquaporin water channels have an important role in endometriosis. Therefore, the aim of this review is to highlight the promising effects of the phytochemicals present in Brassica spp. as major candidates for inclusion in a dietary approach aiming to improve the inflammatory condition of women affected with endometriosis. This review points out the potential roles of glucosinolates and isothiocyanates from Brassicas as anti-inflammatory compounds, which might contribute to a reduction in endometriosis symptoms. In view of these promising results, further investigation of the effect of glucosinolates on chronic inflammatory diseases, either as diet coadjuvants or as therapeutic molecules, should be performed. In addition, we highlight the involvement of aquaporins in the maintenance of immune homeostasis. In brief, glucosinolates and the modulation of cellular water by aquaporins could shed light on new approaches to improve the quality of life for women with endometriosis.

Hypothetical roadmap towards endometriosis: prenatal endocrine-disrupting chemical pollutant exposure, anogenital distance, gut-genital microbiota and subclinical infections

BACKGROUND

Endometriosis is a gynaecological hormone-dependent disorder that is defined by histological lesions generated by the growth of endometrial-like tissue out of the uterus cavity, most commonly engrafted within the peritoneal cavity, although these lesions can also be located in distant organs. Endometriosis affects ~10% of women of reproductive age, frequently producing severe and, sometimes, incapacitating symptoms, including chronic pelvic pain, dysmenorrhea and dyspareunia, among others. Furthermore, endometriosis causes infertility in ~30% of affected women. Despite intense research on the mechanisms involved in the initial development and later progression of endometriosis, many questions remain unanswered and its aetiology remains unknown. Recent studies have demonstrated the critical role played by the relationship between the microbiome and mucosal immunology in preventing sexually transmitted diseases (HIV), infertility and several gynaecologic diseases.

OBJECTIVE AND RATIONALE

In this review, we sought to respond to the main research question related to the aetiology of endometriosis. We provide a model pointing out several risk factors that could explain the development of endometriosis. The hypothesis arises from bringing together current findings from large distinct areas, linking high prenatal exposure to environmental endocrine-disrupting chemicals with a short anogenital distance, female genital tract contamination with the faecal microbiota and the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis.

SEARCH METHODS

We performed a search of the scientific literature published until 2019 in the PubMed database. The search strategy included the following keywords in various combinations: endometriosis, anogenital distance, chemical pollutants, endocrine-disrupting chemicals, prenatal exposure to endocrine-disrupting chemicals, the microbiome of the female reproductive tract, microbiota and genital tract, bacterial vaginosis, endometritis, oestrogens and microbiota and microbiota-immune system interactions.

OUTCOMES

On searching the corresponding bibliography, we found frequent associations between environmental endocrine-disrupting chemicals and endometriosis risk. Likewise, recent evidence and hypotheses have suggested the active role of genital subclinical microbial infections in the development and clinical progression of endometriosis. Hence, we can envisage a direct relationship between higher prenatal exposure to oestrogens or estrogenic endocrine-disrupting compounds (phthalates, bisphenols, organochlorine pesticides and others) and a shorter anogenital distance, which could favour frequent postnatal episodes of faecal microbiota contamination of the vulva and vagina, producing cervicovaginal microbiota dysbiosis. This relationship would disrupt local antimicrobial defences, subverting the homeostasis state and inducing a subclinical inflammatory response that could evolve into a sustained immune dysregulation, closing the vicious cycle responsible for the development of endometriosis.

WIDER IMPLICATIONS

Determining the aetiology of endometriosis is a challenging issue. Posing a new hypothesis on this subject provides the initial tool necessary to design future experimental, clinical and epidemiological research that could allow for a better understanding of the origin of this disease. Furthermore, advances in the understanding of its aetiology would allow the identification of new therapeutics and preventive actions.

The role of non-coding genome in the behavior of infiltrated myeloid-derived suppressor cells in tumor microenvironment; a perspective and state-of-the-art in cancer targeted therapy

Cancer is one of the healthcare problems that affect many communities around the world. Many factors contribute to cancer development. Besides, these factors are counted as the main impediment in cancer immunotherapy. Myeloid-derived suppressor cells (MDSCs) are one of these impediments. MDSCs inhibit the immune responses through various mechanisms such as inhibitory cytokine release and nitric oxide metabolite production. Several factors are involved in forming these cells, including tumor secreted cytokine and chemokines, transcription factors, and non-coding RNA. In the meantime, micro-RNAs (miRNAs) and long non-coding RNAs (lncRNAs) are the vital gene regulatory elements that affect gene expression. In this study, we are going to discuss the role of miRNAs and lncRNAs in MDSCs development in a cancer situation. It is hoped that miRNA and lncRNAs targeting may prevent the growth and development of these inhibitory cells in the cancer environment.

Monocytic myeloid-derived suppressor cells reflect tuberculosis severity and are influenced by cyclooxygenase-2 inhibitors

Myeloid‐derived suppressor cells (MDSCs) increase in tuberculosis (TB) and may be targets for host‐directed therapy (HDT). In this study, we use flow cytometry to analyze the effects of cyclooxygenase‐2 inhibitors (COX‐2i) on monocytic (M)‐MDSCs in blood from TB patients attending a clinical trial of COX‐2i. The effects of COX‐2i on M‐MDSCs and mycobacterial uptake were also studied by an in vitro mycobacterial infection model. We found that M‐MDSC frequencies correlated with TB disease severity. Reduced M‐MDSC (P = 0.05) and IDO (P = 0.03) expression was observed in the COX‐2i group. We show that peripheral blood‐derived M‐MDSCs successfully internalized Mycobacterium bovis and that in vitro mycobacterial infection increased COX‐2 (P = 0.002), PD‐L1 (P = 0.01), and Arginase‐1 (P = 0.002) expression in M‐MDSCs. Soluble IL‐1β, IL‐10, and S100A9 were reduced in COX‐2i‐treated M‐MDSCs cultures (P < 0.05). We show novel data that COX‐2i had limited effect in vivo but reduced M‐MDSC cytokine production in vitro. The relevance of COX‐2i in a HDT strategy needs to be further explored.

Myeloid-Derived Suppressor Cells in Pregnancy and the Neonatal Period

During pregnancy, the immune systems of mother and offspring are challenged by their close adjacency to balance tolerance and rejection. After birth the neonate has to continue this balance towards its new environment by tolerating commensals while rejecting pathogens and towards its developing tissues to avoid inflammatory damage while overcoming immunosuppression. Our group was the first to link immunosuppressive features of myeloid derived suppressor cells (MDSC) to materno-fetal tolerance, neonatal susceptibility to infection and inflammation control. Here we summarize recent advances in this dynamic field.

Biallelic variants/mutations of IL1RAP in patients with steroid-sensitive nephrotic syndrome

Nephrotic syndrome (NS) is a renal disease characterized by severe proteinuria and hypoproteinemia. Although several single-gene mutations have been associated with steroid-resistant NS, causative genes for steroid-sensitive NS (SSNS) have not been clarified. While seeking to identify causative genes associated with SSNS by whole-exome sequencing, we found compound heterozygous variants/mutations (c.524T>C; p.I175T and c.662G>A; p.R221H) of the interleukin-1 receptor accessory protein (IL1RAP) gene in two siblings with SSNS. The siblings' parents are healthy, and each parent carries a different heterozygous IL1RAP variant/mutation. Since IL1RAP is a critical subunit of the functional interleukin-1 receptor (IL-1R), we investigated the effect of these variants on IL-1R subunit function. When stimulated with IL-1β, peripheral blood mononuclear cells from the siblings with SSNS produced markedly lower levels of cytokines compared with cells from healthy family members. Moreover, IL-1R with a variant IL1RAP subunit, reconstituted on a hematopoietic cell line, had impaired binding ability and low reactivity to IL-1β. Thus, the amino acid substitutions in IL1RAP found in these NS patients are dysfunctional variants/mutations. Furthermore, in the kidney of Il1rap-/- mice, the number of myeloid-derived suppressor cells, which require IL-1β for their differentiation, was markedly reduced although these mice did not show significantly increased proteinuria in acute nephrotic injury with lipopolysaccharide treatment. Together, these results identify two IL1RAP variants/mutations in humans for the first time and suggest that IL1RAP might be a causative gene for familial NS.

Inflammasome Deletion Promotes Anti-tumor NK Cell Function in an IL-1/IL-18 Independent Way in Murine Invasive Breast Cancer

Inflammasomes are molecular complexes that trigger an inflammatory response upon detection of pathogens or danger signals. Recent studies suggest that they are also involved in cancer progression. However, their roles during tumorigenesis remain poorly understood and controversial. Here, we investigated whether inflammasome activation supports mammary tumor growth. Using mouse models of invasive breast cancer, our results demonstrate that the absence of a functional inflammasome impairs tumor growth. Importantly, tumors implanted into inflammasome-deficient mice recruited significantly less neutrophils and more natural killer (NK) cells, and these latter cells displayed a more active phenotype. Interestingly, NK cell depletion abolished the anti-tumoral effect observed in inflammasome-deficient mice, although inflammasome-regulated cytokine neutralization had no effect. Thus, our work identifies a novel role for the inflammasome in supporting mammary tumor growth by attenuating NK cell recruitment and activity. These results suggest that inflammasome inhibition could be a putative target for treating invasive breast cancers.

Mechanisms of immune suppression by myeloid-derived suppressor cells: the role of interleukin-10 as a key immunoregulatory cytokine

Chronic immune activation and inflammation are unwanted consequences of many pathological conditions, since they could lead to tissue damage and immune exhaustion, both of which can worsen the pathological condition status. In fact, the immune system is naturally equipped with immunoregulatory cells that can limit immune activation and inflammation. However, chronic activation of downregulatory immune responses is also associated with unwanted consequences that, in turn, could lead to disease progression as seen in the case of cancer and chronic infections. Myeloid-derived suppressor cells (MDSCs) are now considered to play a pivotal role in the pathogenesis of different inflammatory pathological conditions, including different types of cancer and chronic infections. As a potent immunosuppressor cell population, MDSCs can inhibit specific and non-specific immune responses via different mechanisms that, in turn, lead to disease persistence. One such mechanism by which MDSCs can activate their immunosuppressive effects is accomplished by secreting copious amounts of immunosuppressant molecules such as interleukin-10 (IL-10). In this article, we will focus on the pathological role of MDSC expansion in chronic inflammatory conditions including cancer, sepsis/infection, autoimmunity, asthma and ageing, as well as some of the mechanisms by which MDSCs/IL-10 contribute to the disease progression in such conditions.

Human splenic polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) are strategically located immune regulatory cells in cancer

In contrast to the mouse, functional assets of polymorphonuclear myeloid-derived suppressor cells (PMN-MDSC) in the human spleen remain to be better elucidated. Here, we report that the spleen in gastric and pancreatic cancer adopts an immune regulatory character, harbors excessive amount of PMN-MDSC, and anatomically enables their interaction with T cells. Compared to the peripheral blood, the spleen from cancer patients contained significantly higher levels of low-density PMN-MDSC, but not early-stage MDSC (e-MDSC) and monocytic-MDSC (M-MDSC). Low-density fraction of polymorphonuclear (PMN) cells was enriched in immature myeloid cells and displayed higher levels of CD10, CD16, and ROS than their blood-derived counterparts. They were also positive for PD-L1, LOX-1, and pSTAT3. The white pulp and periarteriolar lymphoid sheath (PALS) were strategically surrounded by PMN cells that were in contact with T cells. Unlike those from the blood, both low-density and normal-density PMN cells from the human spleen suppressed T cell proliferation and IFN-γ production. Independent of clinical grade, high PMN-MDSC percentages were associated with decreased survival in gastric cancer. In summary, our results outline the immune regulatory role of the spleen in cancer where neutrophils acquire MDSC functions and feasibly interact with T cells.