Derangement of immune responses by myeloid suppressor cells

Protein Tyrosine Phosphatase CD45 As an Immunity Regulator and a Potential Effector of CAR-T therapy

The leukocyte common antigen CD45 is a receptor tyrosine phosphatase and one of the most prevalent antigens found on the surface of blood cells. CD45 plays a crucial role in the initial stages of signal transmission from receptors of various immune cell types. Immunodeficiency, autoimmune disorders, and oncological diseases are frequently caused by gene expression disorders and imbalances in CD45 isoforms. Despite extensive research into the structure and functions of CD45, the molecular mechanisms behind its role in transmitting signals from T-cell receptors and chimeric antigen receptors remain not fully understood. It is of utmost importance to comprehend the structural features of CD45 and its function in regulating immune system cell activation to study oncological diseases and the impact of CD45 on lymphocytes and T cells modified by chimeric antigen receptors.

TIMM8A is associated with dysfunction of immune cell in BRCA and UCEC for predicting anti-PD-L1 therapy efficacy

Background

TIMM8A is a protein-coding gene located on the X chromosome. There is evidence that TIMM8A plays an important role in mitochondrial morphology and fission. Studies have shown that mitophagy and fission could affect the function of immune cells. However, there is currently no research on this gene’s role in cancer occurrence and progression.

Methods

TIMM8A expression was analyzed via the Tumor Immune Estimation Resource (TIMER) site and UALCAN database. We evaluated the influence of TIMM8A on clinical prognosis using Kaplan-Meier plotter, the PrognoScan database, and Human Protein Atlas (HPA). The correlations between TIMM8A and cancer immune infiltrates were investigated via TIMER. Tumor Immune Dysfunction and Exclusion (TIDE) was used to evaluate the potential of tumor immune evasion. Functions of TIMM8A mutations and 50 genes significantly associated with TIMM8A mutations in breast cancer (BRCA) and uterine corpus endometrial cancer (UCEC) were analyzed by GO and KEGG in LinkedOmics database.

Results

We investigated the role of TIMM8A in multiple cancers and found that it was significantly associated with poor prognosis in BRCA and UCEC. After analyzing the effect of TIMM8A on immune infiltration, we found Th2 CD4+ T cells might be a common pathway by which TIMM8A contributed to poor prognosis in BRCA and UCEC. Our results suggested that myeloid-derived suppressor cells (MDSC) and tumor-associated M2 macrophages (TAM M2) might be important factors in immune evasion through T cell rejection in both cancers, and considered TIMM8A as a biomarker to predict the efficacy of this therapy in BRCA and UCEC. The results of TIMM8A enrichment analysis showed us that abnormally expressed TIMM8A might affect the mitochondrial protein in BRCA and UCEC.

Conclusions

Contributed to illustrating the value of TIMM8A as a prognostic biomarker, our findings suggested that TIMM8A was correlated with prognosis and immune infiltration, including CD8+ T cells, Th2 CD4+ T cells, and macrophages in BRCA and UCEC. In addition, TIMM8A might affect immune infiltration and prognosis in BRCA and UCEC by affecting mitophagy. We believed it could also be a biomarker to predict the efficacy of anti-PD-L1 therapy and proposed to improve the efficacy by eliminating MDSC and TAM M2.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12957-022-02736-6.

The antitumor activity of hPRDX5 against pancreatic cancer and the possible mechanisms

Recombinant human peroxiredoxin-5 (hPRDX5), isolated from anti-cancer bioactive peptide (ACBPs), shows a homology of 89% with goat peroxiredoxin-5 (gPRDX5) and is reported to display anti-tumor activity in vivo. Herein, we explored the effect of hPRDX5 and the responsible mechanism in treating pancreatic cancer. Tumor-bearing mice were randomly divided into normal PBS group and treatment group (n=5; 10 mg/kg hPRDX5). Flow cytometry was employed to examine lymphocytes, myeloid-derived suppressor cell subsets, and the function proteins of natural killer (NK) cells in peripheral blood, spleen, and tumor tissues of mice. Western blot was used to measure the protein expressions of the key nodes in TLR4-MAPK-NF-κB signaling pathway. The rate of tumor suppression was 57.6% at a 10 mg/kg dose in orthotopic transplanted tumor mice. Moreover, the population of CD3+CD4+T cells, NK cells, and CD3+CD8+T cells was significantly increased in the tumor tissue of the hPRDX5 group, while the proportion of granulocytic-myeloid-derived suppressor cells decreased slightly. In addition, after treatment with hPRDX5, the percentage of NK cells in blood increased more than 4-fold. Our findings indicated that hPRDX5 effectively suppressed pancreatic cancer possibly via the TLR4-MAPK-NF-κB signaling cascade; hence hPRDX5 could be a prospective immunotherapy candidate for treating pancreatic cancer.

DAT and TH expression marks human Parkinson's disease in peripheral immune cells

Parkinson's disease (PD) is marked by a loss of dopamine neurons, decreased dopamine transporter (DAT) and tyrosine hydroxylase (TH) expression. However, this validation approach cannot be used for diagnostic, drug effectiveness or investigational purposes in human patients because midbrain tissue is accessible postmortem. PD pathology affects both the central nervous and peripheral immune systems. Therefore, we immunophenotyped blood samples of PD patients for the presence of myeloid derived suppressor cells (MDSCs) and discovered that DAT+/TH+ monocytic MDSCs, but not granulocytic MDSCs are increased, suggesting a targeted immune response to PD. Because in peripheral immune cells DAT activity underlies an immune suppressive mechanism, we investigated whether expression levels of DAT and TH in the peripheral immune cells marks PD. We found drug naïve PD patients exhibit differential DAT+/TH+ expression in peripheral blood mononuclear cells (PBMCs) compared to aged/sex matched healthy subjects. While total PBMCs are not different between the groups, the percentage of DAT+/TH+ PBMCs was significantly higher in drug naïve PD patients compared to healthy controls irrespective of age, gender, disease duration, disease severity or treatment type. Importantly, treatment for PD negatively modulates DAT+/TH+ expressing PBMCs. Neither total nor the percentage of DAT+/TH+ PBMCs were altered in the Alzheimer's disease cohort. The mechanistic underpinning of this discovery in human PD was revealed when these findings were recapitulated in animal models of PD. The reverse translational experimental strategy revealed that alterations in dopaminergic markers in peripheral immune cells are due to the disease associated changes in the CNS. Our study demonstrates that the dopaminergic machinery on peripheral immune cells displays an association with human PD, with exciting implications in facilitating diagnosis and investigation of human PD pathophysiology.

Cancer Immunoediting: Elimination, Equilibrium, and Immune Escape in Solid Tumors

Emphasizing the dynamic processes between cancer and host immune system, the initially discovered concept of cancer immunosurveillance has been replaced by the current concept of cancer immunoediting consisting of three phases: elimination, equilibrium, and escape. Solid tumors composed of both cancer and host stromal cells are an example how the three phases of cancer immunoediting functionally evolve and how tumor shaped by the host immune system gets finally resistant phenotype. The elimination, equilibrium, and escape have been described in this chapter in details, including the role of immune surveillance, cancer dormancy, disruption of the antigen-presenting machinery, tumor-infiltrating immune cells, resistance to apoptosis, as well as the function of tumor stroma, microvesicles, exosomes, and inflammation.

Glioblastoma as an age-related neurological disorder in adults

Background

Advanced age is a major risk factor for the development of many diseases including those affecting the central nervous system. Wild-type isocitrate dehydrogenase glioblastoma (IDH^wt GBM) is the most common primary malignant brain cancer and accounts for ≥90% of all adult GBM diagnoses. Patients with IDH^wt GBM have a median age of diagnosis at 68–70 years of age, and increasing age is associated with an increasingly worse prognosis for patients with this type of GBM.

Methods

The Surveillance, Epidemiology, and End Results, The Cancer Genome Atlas, and the Chinese Glioma Genome Atlas databases were analyzed for mortality indices. Meta-analysis of 80 clinical trials was evaluated for log hazard ratio for aging to tumor survivorship.

Results

Despite significant advances in the understanding of intratumoral genetic alterations, molecular characteristics of tumor microenvironments, and relationships between tumor molecular characteristics and the use of targeted therapeutics, life expectancy for older adults with GBM has yet to improve.

Conclusions

Based upon the results of our analysis, we propose that age-dependent factors that are yet to be fully elucidated, contribute to IDH^wt GBM patient outcomes.

The Preliminary Study for Postoperative Radiotherapy Survival Associated with RUNX3 and TLR9 Expression in Lung Cancer

Background

Many studies have reported that the inflammatory immune response related to TLR9 signaling activation participates in tumor development and affects the treatment outcome. RUNX3 functions as a tumor suppressor by regulating DNA methylation. RUNX3 protein plays an important role in TGF-β signaling pathway that is involved in tumor growth inhibition and apoptosis. At present, radiotherapy is still an important treatment in lung cancer, which induces immune response and affects the therapeutic outcome. The role of TLR9 signaling activation and RUNX3 in this process is not clear.

Methods

In this study, we investigated the expression of TLR9 in tumor and RUNX3 in surrounding tissues by immunohistochemical methods and analyzed the relationship on postoperative survival in lung cancer.

Results

We found that the high expression of TLR9 was the risk factor in postoperative survival of lung cancer with no difference in lifetime. The high expression of RUNX3 in lung cancer with TLR9 signaling activation was in favor of progression-free survival and overall survival in postoperative radiotherapy. It suggested that RUNX3 played an important role in lung cancer radiotherapy. In order to determine the effect of RUNX3 in lung cancer radiation with TLR9 signaling activation, we introduced 5-Aza-2ʹ-deoxycytidine (5-Aza-CdR) and exposed lung cancer A459 cells repeatedly. The high expression of RUNX3 especially RUNX3-B in cells treated with 5-Aza-CdR was observed. We examined that 5-Aza-CdR induced more cell blocking in G2/M phase in combining irradiation.

Conclusion

The result implied that it was feasible to improve radiosensitivity of lung cancer with TLR9 signaling activation by increasing RUNX3 expression, and 5-Aza-CdR was an option in this process.

Comments on the ambiguity of selected surface markers, signaling pathways and omics profiles hampering the identification of myeloid-derived suppressor cells

Myeloid-derived suppressor cells (MDSC) are important immune-regulatory cells but their identification remains difficult. Here, we provide a critical view on selected surface markers, transcriptional and translational pathways commonly used to identify MDSC by specific, their developmental origin and new possibilities by transcriptional or proteomic profiling. Discrimination of MDSC from their non-suppressive counterparts is a prerequisite for the development of successful therapies. Understanding the switch mechanisms that direct granulocytic and monocytic development into a pro-inflammatory or anti-inflammatory direction will be crucial for therapeutic strategies. Manipulation of these myeloid checkpoints are exploited by tumors and pathogens, such as M. tuberculosis (Mtb), HIV or SARS-CoV-2, that induce MDSC for immune evasion. Thus, specific markers for MDSC identification may reveal also novel molecular candidates for therapeutic intervention at the level of MDSC.

Biomineralized Biohybrid Algae for Tumor Hypoxia Modulation and Cascade Radio-Photodynamic Therapy

Biomineralization of biomaterials has shown extraordinary potential in cancer treatment, but the exploration of their in vivo applications is still insufficient. Here, we report a biohybrid microalgae system using a biomineralization approach to improve their biocompatibility, while keeping their living activities for radiation and photodynamic synergistic therapy in breast cancer. The biohybrid algae (Algae@SiO₂) synthesized by a one-step biomimetic silicification method could significantly enhance their cytotoxicity and tolerance, improving the living activity in the tumor area. The innate chlorophyll and unique optical property make Algae@SiO₂ possess dual imaging ability, namely, photoacoustic imaging and fluorescence imaging. Algae@SiO₂ accumulated in tumor sites could generate oxygen in situ by external light-mediated photosynthesis, relieve tumor hypoxia, and then enhance the efficiency of radiation therapy. As a natural photosensitizer, the released chlorophyll from Algae@SiO₂ could provide reactive oxygen species to kill the cancer cells for the cascaded photodynamic therapy. The significant suppression of tumor growth in the mice bearing 4T1 tumor successfully demonstrates the promising anti-tumor effect of the Algae@SiO₂-mediated synergistic therapy. Our results show that biohybrid algae, integrated with PAI/FI dual imaging, radiosensitization, and cascaded photothermal therapy, is a promising multifunctional efficient biosystem for cancer treatment.

Combination therapy with liposomal doxorubicin and liposomal vaccine containing E75, an HER-2/neu-derived peptide, reduces myeloid-derived suppressor cells and improved tumor therapy

Myeloid-derived suppressor cells (MDSCs) are immunosuppressive cells causing resistance to immunotherapies in cancer tumors. In the current study, various immunogenic and therapeutic features of the combination therapies with non-liposomal Doxorubicin (Dox) and the E75 immunogenic peptide (Pep), derived from the human epidermal receptor-2 (HER-2), are investigated in parallel with their liposomal formulations (Lip-Dox (Doxil®) and Lip-Pep). Therefore, triple injection doses of Lip-Pep were preceded with Dox and Lip-Dox injections in TUBO/breast tumor-bearing BALB/c mice. Chemotherapy with either Dox or Lip-Dox reduced the frequency of MDSCs, the level of reactive oxygen species (ROS), and MDSCs-associated genes of Arg1, iNOS, S100A8, S100A9. Whereas Lip-Pep + Dox and Lip-Pep + Lip-Dox treatments synergistically potentiated the immunized splenocytes to produce INF-γ and enhanced the frequency of the anti-tumor CD8⁺ and CD4⁺ T cells as opposed to both chemotherapy and immunotherapy regimens. Chemo-immunotherapy increased the number of tumor-infiltrating lymphocytes (TILs) and reduced the level of CD25⁺ FoxP3⁺ T regulatory cells. Taken together, chemo-immunotherapy was the optimum treatment for the limitation of tumor progression as they targeted more cancer-related immune players.

Cordyceps militaris polysaccharide converts immunosuppressive macrophages into M1-like phenotype and activates T lymphocytes by inhibiting the PD-L1/PD-1 axis between TAMs and T lymphocytes

Tumour-associated macrophages (TAMs) inhibit the killing effect of T lymphocytes on tumour cells through the immunocheckpoint programmed death ligand-1 (PD-L1)/programmed death-1 (PD-1) axis. TAMs-targeted therapy is a promising approach that could be used to reverse the immunosuppressive tumour microenvironment. Here, we further report CMPB90-1, a novel natural polysaccharide from Cordyceps militaris, could function as an anti-tumour modulator that resets TAMs from a tumour-promoting M2 phenotype to a tumour-killing M1 phenotype. This process involves reversing the functional inhibition of T lymphocytes by inhibiting the PD-L1/PD-1 axis between TAMs and T lymphocytes. Mechanistically, the membrane receptor of CMPB90-1 binding to M2 macrophages was identified by tandem mass spectrometry. CMPB90-1 converts immunosuppressive TAMs via binding to toll-like receptor 2 (TLR2), which causes the release of Ca²⁺ and the activation of p38, Akt and NF-κB, or ERK. This process then leads to the polarization of TAMs from M2 phenotype to the M1 phenotype. In vivo experiment shows that CMPB90-1 is able to polarize TAMs into the M1 phenotype and has anti-tumour effects with improved safety. Additionally, the anti-tumour effects of CMPB90-1 in vivo depend on the phenotypic conversion of TAMs. The results demonstrated that CMPB90-1 could be developed as a potential immune-oncology treatment reagent.

Chemokines and their Receptors: Multifaceted Roles in Cancer Progression and Potential Value as Cancer Prognostic Markers

Chemokines are chemotactic cytokines that mediate immune cell chemotaxis and lymphoid tissue development. Recent advances have indicated that chemokines and their cognate receptors play critical roles in cancer-related inflammation and cancer progression. On the basis of these findings, the chemokine system has become a new potential drug target for cancer immunotherapy. In this review, we summarize the essential roles of the complex network of chemokines and their receptors in cancer progression. Furthermore, we discuss the potential value of the chemokine system as a cancer prognostic marker. The chemokine system regulates the infiltration of immune cells into the tumor microenvironment, which induces both pro- and anti-immunity and promotes or suppresses tumor growth and proliferation, angiogenesis, and metastasis. Increasing evidence indicates the promising prognostic value of the chemokine system in cancer patients. While CCL2, CXCL10, and CX3CL1/CX3CR1 can serve as favorable or unfavorable prognostic factors depending on the cancer types, CCL14 and XCL1 possess good prognostic value. Other chemokines such as CXCL1, CXCL8, and CXCL12 are poor prognostic markers. Despite vast advances in our understanding of the complex nature of the chemokine system in tumor biology, knowledge about the multifaceted roles of the chemokine system in different types of cancers is still limited. Further studies are necessary to decipher distinct roles within the chemokine system in terms of cancer progression and to validate their potential value in cancer prognosis.

Knockdown of serine/threonine-protein kinase 24 promotes tumorigenesis and myeloid-derived suppressor cell expansion in an orthotopic immunocompetent gastric cancer animal model

A higher incidence of gastric cancer has been found in East Asia compared to the incidence in other regions. Gastric cancer patients have a poor prognosis due to distant metastasis and advanced cancer stages. Tumor escape pathways include the expansion of the immunosuppressive myeloid-derived suppressor cells (MDSCs) in the tumor microenvironment. We have successfully established an orthotopic immunocompetent gastric cancer model in C57BL/6 mice. The cell line is named M12 and was deposited at the Bioresource Collection and Research Center of Taiwan on Sep. 13, 2016 (Patent No. I604054). The orthotopic animal model of gastric cancer has similar biological characteristics as human gastric cancer. Serine/threonine-protein kinase 24 (STK24) is a member of the germinal center kinase (GCK)-III family. GCKs participate in cancer and immunological disorders. The effects of STK24 in gastric cancer are less well understood. CRISPR (clustered regularly interspaced short palindromic repeats)/Cas9 technology was used to induce a STK24 genetic knockout at the genomic DNA level in tumor cells. The knockdown of the STK24 gene increased the tumor growth in an orthotopic model of gastric cancer. The STK24 gene silencing in tumors induced the expansion of CD11b⁺Ly6C⁺ cells and F4/80⁺ macrophages in vivo. To our knowledge, we have developed the first orthotopic transplantable model of gastric cancer in syngeneic inbred mice. Our results further indicate that STK24 is important for immune regulation during the tumorigenesis of gastric cancer.

Chemokines and their receptors promoting the recruitment of myeloid-derived suppressor cells into the tumor

Myeloid-derived suppressor cells (MDSCs) expand in tumor-bearing host. They suppress anti-tumor immune response and promote tumor growth. Chemokines play a vital role in recruiting MDSCs into tumor tissue. They can also induce the generation of MDSCs in the bone marrow, maintain their suppressive activity, and promote their proliferation and differentiation. Here, we review CCL2/CCL12-CCR2, CCL3/4/5-CCR5, CCL15-CCR1, CX3CL1/CCL26-CX3CR1, CXCL5/2/1-CXCR2, CXCL8-CXCR1/2, CCL21-CCR7, CXCL13-CXCR5 signaling pathways, their role in MDSCs recruitment to tumor tissue, and their correlation with tumor development, metastasis and prognosis. Targeting chemokines and their receptors may serve as a promising strategy in immunotherapy, especially combined with other strategies such as chemotherapy, cyclin-dependent kinase or immune checkpoints inhibitors.

Bioprofiling TS/A Murine Mammary Cancer for a Functional Precision Experimental Model

The TS/A cell line was established in 1983 from a spontaneous mammary tumor arisen in an inbred BALB/c female mouse. Its features (heterogeneity, low immunogenicity and metastatic ability) rendered the TS/A cell line suitable as a preclinical model for studies on tumor-host interactions and for gene therapy approaches. The integrated biological profile of TS/A resulting from the review of the literature could be a path towards the description of a precision experimental model of mammary cancer.

Frequency and Implications of myeloid-derived suppressor cells and lymphocyte subsets in Egyptian patients with hepatitis C virus-related hepatocellular carcinoma

BACKGROUND AND AIM

Myeloid-derived suppressor cells (MDSCs) play a pivotal role in tumor immunity and induction of immune tolerance to a variety of antitumor effectors, including T lymphocytes. Herein, we tried to evaluate the frequency and clinical significance of MDSCs and different lymphocyte subsets in hepatitis C virus (HCV)-related hepatocellular carcinoma (HCC).

METHODS

Four groups were enrolled; chronic HCV (CHC; n = 40), HCV-related liver cirrhosis (n = 40), HCV-related HCC (HCV-HCC; n = 75), and healthy control group (n = 20). The percentage of peripheral lymphocytes subsets and total MDSCs with their main two subsets; monocytic (M-MDSCs) and granulocytic (G-MDSCs) was evaluated by flow cytometry.

RESULTS

The frequency of total MSDCs and M-MDSCs was significantly elevated in HCV-HCC especially patients with advanced stage HCC compared with those with early-stage HCC. The frequency of total MSDCs and M-MDSCs was positively correlated with ALT, AFP, and HCV viral load and negatively correlated with CD8⁺ T-cell frequency. CD4 ⁺ T cells were significantly decreased in HCV-HCC patients. The frequency of CD4 ⁺ T cells and CD8 ⁺ T cells was negatively correlated with AFP and AST, but not with albumin or HCV viral load.

CONCLUSION

Taken together, our data suggest that MDSCs, M-MDSCs, and lymphocyte subsets are associated with the development and progression of HCV-related HCC.

Targeting Metalloenzymes for Therapeutic Intervention

Metalloenzymes are central to a wide range of essential biological activities, including nucleic acid modification, protein degradation, and many others. The role of metalloenzymes in these processes also makes them central for the progression of many diseases and, as such, makes metalloenzymes attractive targets for therapeutic intervention. Increasing awareness of the role metalloenzymes play in disease and their importance as a class of targets has amplified interest in the development of new strategies to develop inhibitors and ultimately useful drugs. In this Review, we provide a broad overview of several drug discovery efforts focused on metalloenzymes and attempt to map out the current landscape of high-value metalloenzyme targets.

Selenopheno[2,3-f]coumarins: novel scaffolds with antimetastatic activity against melanoma and breast cancer

The general aim of the current research is to find novel non-toxic small molecules with antimetastatic activity.

Chemokine (C-X-C motif) ligand 1 and CXCL2 produced by tumor promote the generation of monocytic myeloid-derived suppressor cells

Accumulation of myeloid‐derived suppressor cells (MDSC) in tumor‐bearing hosts is a hallmark of tumor‐associated inflammation, which is thought to be a barrier to immunosurveillance. Multiple factors secreted by tumor cells and tumor stromal cells are reported to be involved in promoting the expansion of MDSC. Herein, we showed that s.c. inoculation of tumor cells and i.v. injection of tumor‐conditioned medium increased the number of MDSC. Subsequent investigation elucidated that chemokine (C‐X‐C motif) ligand 1 (CXCL1) and CXCL2, which were originally characterized as the chemokines of neutrophils, specifically promoted the expansion of monocytic MDSC (mo‐MDSC), a subtype of MDSC, in the presence of granulocyte‐macrophage colony‐stimulating factor. Depletion of CXCL1 or CXCL2 in B16F10 cells or in B16F10‐bearing mice noticeably decreased the generation of mo‐MDSC in bone marrow. Moreover, we found that, in addition to the tumor cells, tumor‐infiltrated CD11b⁺ myeloid cells also expressed CXCL1 and CXCL2. Furthermore, CXCL1‐ and CXCL2‐induced increase of mo‐MDSC was not correlated with chemotaxis, proliferation or apoptosis of mo‐MDSC. These findings show a novel role of CXCL1 and CXCL2 in promoting mo‐MDSC generation by favoring the differentiation of bone marrow cells in tumor‐bearing conditions, which suggests that inhibition of CXCL1 and CXCL2 could decrease mo‐MDSC generation and improve host immunosurveillance.

Cannabidiol Attenuates Experimental Autoimmune Encephalomyelitis Model of Multiple Sclerosis Through Induction of Myeloid-Derived Suppressor Cells

Multiple sclerosis (MS) is a chronic debilitating autoimmune disease without a cure. While the use of marijuana cannabinoids for MS has recently been approved in some countries, the precise mechanism of action leading to attenuate neuroinflammation is not clear. We used experimental autoimmune encephalomyelitis (EAE), a murine model of MS, to explore the anti-inflammatory properties of cannabidiol (CBD), a non-psychoactive cannabinoid. Treatment with CBD caused attenuation of EAE disease paradigms as indicated by a significant reduction in clinical scores of paralysis, decreased T cell infiltration in the central nervous system, and reduced levels of IL-17 and IFNγ. Interestingly, CBD treatment led to a profound increase in myeloid-derived suppressor cells (MDSCs) in EAE mice when compared to the vehicle-treated EAE controls. These MDSCs caused robust inhibition of MOG-induced proliferation of T cells in vitro. Moreover, adoptive transfer of CBD-induced MDSCs ameliorated EAE while MDSC depletion reversed the beneficial effects of CBD treatment, thereby conclusively demonstrating that MDSCs played a crucial role in CBD-mediated attenuation of EAE. Together, these studies demonstrate for the first time that CBD treatment may ameliorate EAE through induction of immunosuppressive MDSCs.

Oncolytic viruses as engineering platforms for combination immunotherapy

To effectively build on the recent successes of immune checkpoint blockade, adoptive T cell therapy and cancer vaccines, it is critical to rationally design combination strategies that will increase and extend efficacy to a larger proportion of patients. For example, the combination of anti-cytotoxic T lymphocyte-associated antigen 4 (CTLA4) and anti-programmed cell death protein 1 (PD1) immune checkpoint inhibitors essentially doubles the response rate in certain patients with metastatic melanoma. However, given the heterogeneity of cancer, it seems likely that even more complex combinations of immunomodulatory agents may be required to obtain consistent, durable therapeutic responses against a broad spectrum of cancers. This carries serious implications in terms of toxicities for patients, feasibility for care providers and costs for health-care systems. A compelling solution is offered by oncolytic viruses (OVs), which can be engineered to selectively replicate within and destroy tumour tissue while simultaneously augmenting antitumour immunity. In this Opinion article, we argue that the future of immunotherapy will include OVs that function as multiplexed immune-modulating platforms expressing factors such as immune checkpoint inhibitors, tumour antigens, cytokines and T cell engagers. We illustrate this concept by following the trials and tribulations of tumour-reactive T cells from their initial priming through to the execution of cytotoxic effector function in the tumour bed. We highlight the myriad opportunities for OVs to help overcome critical barriers in the T cell journey, leading to new synergistic mechanisms in the battle against cancer.

Endogenous Protection from Ischemic Brain Injury by Preconditioned Monocytes

Exposure to low-dose lipopolysaccharide (LPS) before cerebral ischemia is neuroprotective in stroke models, a phenomenon termed preconditioning (PC). Although it is well established that LPS-PC induces central and peripheral immune responses, the cellular mechanisms modulating ischemic injury remain unclear. Here, we investigated the role of immune cells in the brain protection afforded by PC and tested whether monocytes may be reprogrammed by ex vivo LPS exposure, thus modulating inflammatory injury after cerebral ischemia in male mice. We found that systemic injection of low-dose LPS induces a Ly6C^hi monocyte response that protects the brain after transient middle cerebral artery occlusion (MCAO) in mice. Remarkably, adoptive transfer of monocytes isolated from preconditioned mice into naive mice 7 h after transient MCAO reduced brain injury. Gene expression and functional studies showed that IL-10, inducible nitric oxide synthase, and CCR2 in monocytes are essential for neuroprotection. This protective activity was elicited even if mouse or human monocytes were exposed ex vivo to LPS and then injected into male mice after stroke. Cell-tracking studies showed that protective monocytes are mobilized from the spleen and reach the brain and meninges, where they suppress postischemic inflammation and neutrophil influx into the brain parenchyma. Our findings unveil a previously unrecognized subpopulation of splenic monocytes capable of protecting the brain with an extended therapeutic window and provide the rationale for cell therapies based on the delivery of autologous or allogeneic protective monocytes in patients after ischemic stroke.SIGNIFICANCE STATEMENT Inflammation is a key component of the pathophysiology of the brain in stroke, a leading cause of death and disability with limited therapeutic options. Here, we investigate endogenous mechanisms of protection against cerebral ischemia. Using lipopolysaccharide (LPS) preconditioning (PC) as an approach to induce ischemic tolerance in mice, we found generation of neuroprotective monocytes within the spleen, from which they traffic to the brain and meninges, suppressing postischemic inflammation. Importantly, systemic LPS-PC can be mimicked by adoptive transfer of in vitro-preconditioned mouse or human monocytes at translational relevant time points after stroke. This model of neuroprotection may facilitate clinical efforts to increase the efficacy of BM mononuclear cell treatments in acute neurological diseases such as cerebral ischemia.

Blockade of CCL2 enhances immunotherapeutic effect of anti-PD1 in lung cancer

Myeloid derived suppressor cells (MDSC) play a pivotal role in tumor immune evasion and MDSC levels increased in patients with cancer. Studies confirmed the associations between MDSC and various cytokines in the peripheral blood. However, little is known about the association between parenchymal MDSC subsets and cytokines, or the mechanism drawing MDSC into tumor parenchyma. This study was to analyze the correlation between MDSC subsets and CCL2 level in lung cancer model. G-MDSC and M-MDSC from the blood and parenchyma were analyzed by flow cytometry and western blot in the lung tumor model. CCL2 was detected by ELISA assay, real-time PCR, western blot and flow cytometry. Furthermore, the therapeutic effects of combination treatment combining CCL2 antagonist and anti-PD1 antibody were assessed. Results showed that MDSC subsets had a positive correlation with CCL2, suggesting CCL2 may attract MDSC into the parenchyma. Gene and protein expression of CCL2, as well as the CCL2 surface expression significantly increased in blood and tumor of tumor-bearing mice. Anti-CCL2 treatment decreased G-MDSC and M-MDSC in the periphery and tumor through inhibiting the protein expression of arginase 1 and iNOS. In addition, combination therapy enhanced CD4⁺ and CD8⁺ T cell infiltration, as well as the production of interferon gamma (IFNγ), and increased the survival time of tumor-bearing mice. Our study provided potential new target to enhance the efficacy of immunotherapy in patients with lung cancer, in addition to elucidate a possible association between MDSC subsets and the cytokine drawing MDSC migration into the tumor tissue.

Blockade of CCR5-mediated myeloid derived suppressor cell accumulation enhances anti-PD1 efficacy in gastric cancer

PURPOSE

Myeloid derived suppressor cells (MDSC) play an important role in tumor immune evasion and its level significantly increased in patients with gastric cancer. Studies confirmed the associations between MDSC and various cytokines in the peripheral blood. However, little is known about the mechanism drawing MDSC into tumor parenchyma. This study was to analyze the correlation between MDSC subsets and CCR5 level in gastric cancer.

MATERIALS AND METHODS

G-MDSC and M-MDSC from the peripheral blood and tumor parenchyma were analyzed by flow cytometry. CCR5 ligand CCL5 was detected by ELISA. CCR5 was detected by real-time PCR, western blot and flow cytometry. Furthermore, the therapeutic effects of CCR5 blockade was assessed by the tumor model.

RESULTS

CCR5 ligand, gene and protein expression of CCR5, and surface expression of CCR5 significantly increased in blood and tumor of tumor-bearing mice, suggesting MDSC may be attracted into the parenchyma by CCL5/CCR5. Anti-CCR5 treatment decreased G-MDSC and M-MDSC in the periphery and tumor. In addition, combination treatment enhanced CD4+ and CD8+ T cell infiltration and decreased the tumor burden of tumor-bearing mice.

CONCLUSIONS

This study elucidated a possible association between MDSC subsets and CCR5, in addition to provide a new potential target to enhance the efficacy of immunotherapy in patients with gastric cancer.

Myeloid-derived suppressor cells in ovarian cancer: friend or foe?

Although previous decades contributed to major progress in targeted therapy of many malignancies, the treatment of gynaecological cancers remains a challenging task. In the evidence of rising cancer mortality, the search for new methods of treatment is a dire need. Exploring the mechanisms of interaction between tumour cells and host immune response may allow the introduction of new, effective therapies – not as toxic and far more efficient than conventional methods of cancer treatment. Epithelial ovarian cancer (EOC) is typically diagnosed at advanced stages. Its incidence and mortality rate is high. Powerful diagnostic tools for this kind of cancer are still under investigation. Multiple mechanisms existing in the ovarian tumour network create a specific immunosuppressive microenvironment, in which accumulation of myeloid-derived suppressor cells (MDSCs) may be a critical component for diagnosis and treatment. This review attempts to verify current knowledge on the role of MDSCs in EOC.

Recruited monocytic myeloid-derived suppressor cells promote the arrest of tumor cells in the premetastatic niche through an IL-1β-mediated increase in E-selectin expression

The tumor premetastatic niche initiated by primary tumors is constructed by multiple molecular factors and cellular components and provides permissive condition that allows circulating tumor cells to successfully metastasize. Myeloid-derived suppressor cells (MDSCs), a population of immature cells in pathological conditions, play a critical role in the formation of the premetastatic niche. However, few researches are focused on the function of monocytic MDSCs (mo-MDSCs), a subtype of MDSCs, in the construction of the niche. Here, we show that the number of mo-MDSCs is significantly increased in the premetastatic lungs of tumor-bearing mice, thus promoting tumor cell arrest and metastasis. Before the arrival of tumor cells, the lung-recruited mo-MDSCs produced IL-1β, thereby increasing E-selectin expression and promoting tumor cell arrest on endothelial cells. Depletion of mo-MDSCs in the premetastatic lungs decreased IL-1β production, resulting in reduced E-selectin expression. In addition, compared with alveolar macrophages and interstitial macrophages, mo-MDSCs were the major source of IL-1β expression in the premetastatic lungs. Cytokine array analyses and transwell experiments revealed that CCL12 recruits mo-MDSCs to premetastatic lungs. CCL12 knockdown in tumor-bearing mice significantly decreased mo-MDSC infiltration into the premetastatic lungs, leading to reduced E-selectin expression. Overall, the permissive conditions produced by the infiltrated mo-MDSCs correlated with increased tumor cell arrest and metastasis. These results reveal a novel role of mo-MDSCs in constructing the premetastatic niche. Thus, inhibition of mo-MDSCs infiltration may change the premetastatic niche to normal condition and attenuate tumor metastasis.

Histone deacetylase inhibitors deplete myeloid-derived suppressor cells induced by 4T1 mammary tumors in vivo and in vitro

Myeloid-derived suppressor cells (MDSC) have been identified as a population of immature myeloid cells that suppress anti-tumor immunity. MDSC are increased in tumor-bearing hosts; thus, depletion of MDSC may enhance anti-tumor immunity. Histone deacetylase inhibitors (HDACi) are chemical agents that are primarily used against hematologic malignancies. The ability of these agents to modulate anticancer immunity has recently been extensively studied. However, the effect of HDACi on MDSC has remained largely unexplored. In the present study, we provide the first demonstration that HDACi treatment decreases MDSC accumulation in the spleen, blood and tumor bed but increases the proportion of T cells (particularly the frequency of IFN-γ- or perforin-producing CD8+ T cells) in BALB/C mice with 4T1 mammary tumors. In addition, HDACi exposure of bone marrow (BM) cells significantly eliminated the MDSC population induced by GM-CSF or the tumor burden in vitro, which was further demonstrated as functionally important to relieve the inhibitory effect of MDSC-enriched BM cells on T cell proliferation. Mechanistically, HDACi increased the apoptosis of Gr-1+ cells (almost MDSC) compared with that of Gr-1- cells, which was abrogated by the ROS scavenger N-acetylcysteine, suggesting that the HDACi-induced increase in MDSC apoptosis due to increased intracellular ROS might partially account for the observed depletion of MDSC. These findings suggest that the elimination of MDSC using an HDACi may contribute to the overall anti-tumor properties of these agents, highlighting a novel property of HDACi as potent MDSC-targeting agents, which may be used to enhance the efficacy of immunotherapeutic regimens.

The role of the immune system in neurofibromatosis type 1-associated nervous system tumors

With the recent development of new anticancer therapies targeting the immune system, it is important to understand which immune cell types and cytokines play critical roles in suppressing or promoting tumorigenesis. The role of mast cells in promoting neurofibroma growth in neurofibromatosis type 1 (NF1) patients was hypothesized decades ago. More recent experiments in mouse models have demonstrated the causal role of mast cells in neurofibroma development and of microglia in optic pathway glioma development. We review here what is known about the role of NF1 mutation in immune cell function and the role of immune cells in promoting tumorigenesis in NF1. We also review the therapies targeting immune cell pathways and their promise in NF1 tumors.

Immature myeloid-derived suppressor cells: A bridge between inflammation and cancer (Review)

Chronic inflammation is considered to be one of the hallmarks of tumor initiation and progression. Changes occurring in the microenvironment of progressing tumors resemble the process of chronic inflammation, which begins with ischemia followed by interstitial and cellular edema, appearance of immune cells, growth of blood vessels and tissue repair, and development of inflammatory infiltrates. Moreover, long‑term production and accumulation of inflammatory factors lead to local and systemic immunosuppression associated with cancer progression. Of the several mechanisms described to explain this anergy, the accumulation of myeloid cells in the tumor, spleen, and peripheral blood of cancer patients has gained considerable interest. A population of suppressive CD11b+Gr-1+ cells has in fact been designated as myeloid-derived suppressor cells (MDSCs). MDSCs are a unique category of the myeloid lineage, and they induce the prevention of the development of cytotoxic T lymphocytes (CTLs) in vitro, and the induction of antigen-specific CD8+ T-cell tolerance in vivo. Therapeutic approaches directed toward the manipulation of the MDSC population and their function may improve chemoimmune-enhancing therapy for advanced malignancies.

Cooperative therapeutic anti-tumor effect of IL-15 agonist ALT-803 and co-targeting soluble NKG2D ligand sMIC

Shedding of the human NKG2D ligand MIC (MHC class I-chain-related molecule) from tumor cell surfaces correlates with progression of many epithelial cancers. Shedding-derived soluble MIC (sMIC) enables tumor immune escape through multiple immune suppressive mechanisms, such as disturbing natural killer (NK) cell homeostatic maintenance, impairing NKG2D expression on NK cells and effector T cells, and facilitating the expansion of arginase I+ myeloid suppressor cells. Our recent study has demonstrated that sMIC is an effective cancer therapeutic target. Whether targeting tumor-derived sMIC would enhance current active immunotherapy is not known. Here, we determined the in vivo therapeutic effect of an antibody co-targeting sMIC with the immunostimulatory IL-15 superagonist complex, ALT-803, using genetically engineered transplantable syngeneic sMIC+ tumor models. We demonstrate that combined therapy of a nonblocking antibody neutralizing sMIC and ALT-803 improved the survival of animals bearing sMIC+ tumors in comparison to monotherapy. We further demonstrate that the enhanced therapeutic effect with combined therapy is through concurrent augmentation of NK and CD8 T cell anti-tumor responses. In particular, expression of activation-induced surface molecules and increased functional potential by cytokine secretion are improved greatly by the administration of combined therapy. Depletion of NK cells abolished the cooperative therapeutic effect. Our findings suggest that administration of the sMIC-neutralizing antibody can enhance the anti-tumor effects of ALT-803. With ALT-803 currently in clinical trials to treat progressive solid tumors, the majority of which are sMIC+, our findings provide a rationale for co-targeting sMIC to enhance the therapeutic efficacy of ALT-803 or other IL-15 agonists.

Myeloid-Derived Suppressor Cell Subset Accumulation in Renal Cell Carcinoma Parenchyma Is Associated with Intratumoral Expression of IL1β, IL8, CXCL5, and Mip-1α

Purpose: Little is known about the association between myeloid-derived suppressor cell (MDSC) subsets and various chemokines in patients with renal cell carcinoma (RCC) or the factors that draw MDSC into tumor parenchyma.Experimental Design: We analyzed polymorphonuclear MDSC (PMN-MDSC), monocytic MDSC (M-MDSC), and immature MDSC (I-MDSC) from the parenchyma and peripheral blood of 48 patients with RCC, isolated at nephrectomy. We analyzed levels of IL1β, IL8, CXCL5, Mip-1α, MCP-1, and Rantes. Furthermore, we performed experiments in a Renca murine model to assess therapeutic synergy between CXCR2 and anti-PD1 and to elucidate the impact of IL1β blockade on MDSC.Results: Parenchymal PMN-MDSC have a positive correlation with IL1β, IL8, CXCL5, and Mip-1α, and I-MDSC correlate with IL8 and CXCL5. Furthermore, peripheral PMN-MDSC correlate with tumor grade. Given that PMN-MDSC express CXCR2 and parenchymal PMN-MDSC correlated with IL8 and CXCL5, we assessed the response of CXCR2 blockade with or without anti-PD1. Combination therapy reduced tumor weight and enhanced CD4⁺ and CD8⁺ T-cell infiltration. In addition, anti-IL1β decreased PMN-MDSC and M-MDSC in the periphery, PMN-MDSC in the tumor, and peripheral CXCL5 and KC. Anti-IL1β also delayed tumor growth.Conclusions: Parenchymal PMN-MDSC have a positive correlation with IL1β, IL8, CXCL5, and Mip-1α, suggesting they may attract PMN-MDSC into the tumor. Peripheral PMN-MDSC correlate with tumor grade, suggesting prognostic significance. Anti-CXCR2 and anti-PD1 synergized to reduce tumor weight and enhanced CD4⁺ and CD8⁺ T-cell infiltration in a Renca murine model, suggesting that CXCR2⁺ PMN-MDSC are important in reducing activity of anti-PD1 antibody. Finally, anti-IL1β decreases MDSC and delayed tumor growth, suggesting a potential target for MDSC inhibition. Clin Cancer Res; 23(9); 2346-55. ©2016 AACR.

Tumor-Produced Interleukin-8 Attracts Human Myeloid-Derived Suppressor Cells and Elicits Extrusion of Neutrophil Extracellular Traps (NETs)

PURPOSE

Myeloid-derived suppressor cells (MDSC) are considered an important T-cell immunosuppressive component in cancer-bearing hosts. The factors that attract these cells to the tumor microenvironment are poorly understood. IL8 (CXCL8) is a potent chemotactic factor for neutrophils and monocytes.

EXPERIMENTAL DESIGN

MDSC were characterized and sorted by multicolor flow cytometry on ficoll-gradient isolated blood leucokytes from healthy volunteers (n = 10) and advanced cancer patients (n = 28). In chemotaxis assays, sorted granulocytic and monocytic MDSC were tested in response to recombinant IL8, IL8 derived from cancer cell lines, and patient sera. Neutrophil extracellular traps (NETs) formation was assessed by confocal microscopy, fluorimetry, and time-lapse fluorescence confocal microscopy on short-term MDSC cultures.

RESULTS

IL8 chemoattracts both granulocytic (GrMDSC) and monocytic (MoMDSC) human MDSC. Monocytic but not granulocytic MDSC exerted a suppressor activity on the proliferation of autologous T cells isolated from the circulation of cancer patients. IL8 did not modify the T-cell suppressor activity of human MDSC. However, IL8 induced the formation of NETs in the GrMDSC subset.

CONCLUSIONS

IL8 derived from tumors contributes to the chemotactic recruitment of MDSC and to their functional control. Clin Cancer Res; 22(15); 3924-36. ©2016 AACR.

Distinct courses of infection with Leishmania (L.) amazonensis are observed in BALB/c, BALB/c nude and C57BL/6 mice

Leishmania (L.) amazonensis [L. (L.) amazonensis] is widely distributed in Brazil and its symptomatic infections usually lead to few localized lesions and sometimes to diffuse cutaneous form, with nodules throughout the body, anergy to parasite antigens and poor therapeutic response. The variability of these manifestations draws attention to the need for studies on the pathophysiology of infection by this species. In this study, we analysed the course and immunological aspects of L. (L.) amazonensis infection in BALB/c and C57BL/6 strains, both susceptible, but displaying different clinical courses, and athymic BALB/c nude, to illustrate the role of T cell dependent responses. We analysed footpad thickness and parasite burden by in vivo imaging. Furthermore, we evaluated the cellular profile and cytokine production in lymph nodes and the inflammatory infiltrates of lesions. Nude mice showed delayed lesion development and less inflammatory cells in lesions, but higher parasite burden than BALB/c and C57BL/6. BALB/c and C57BL/6 mice had similar parasite burdens, lesion sizes and infiltrates until 6 weeks after infection, and after that C57BL/6 mice controlled the infection. Small differences in parasite numbers were observed in C57BL/6 macrophages in vitro, indicating that in vivo milieu accounts for most differences in infection. We believe our results shed light on the role of host immune system in the course of L. (L.) amazonensis infection by comparing three mouse strains that differ in parasitaemia and inflammatory cells.

Tumor Presence Induces Global Immune Changes and Enhances Nanoparticle Clearance

Long-circulating nanoparticles are essential for increasing tumor accumulation to provide therapeutic efficacy. While it is known that tumor presence can alter the immune system, very few studies have explored this impact on nanoparticle circulation. In this report, we demonstrate how the presence of a tumor can change the local and global immune system, which dramatically increases particle clearance. We found that tumor presence significantly increased clearance of PRINT hydrogel nanoparticles from the circulation, resulting in increased accumulation in the liver and spleen, due to an increase in M2-like macrophages. Our findings highlight the need to better understand interactions between immune status and nanoparticle clearance, and suggest that further consideration of immune function is required for success in preclinical and clinical nanoparticle studies.

Expansion and functions of myeloid-derived suppressor cells in the tumor microenvironment

Myeloid derived suppressor cells (MDSCs) are a group of immature myeloid cells accumulated in most cancer patients and mouse tumor models. MDSCs suppress host immune response and concurrently promote tumor angiogenesis, thereby promote tumor growth and progression. In this review, we discuss recent progresses in expansion and activity of tumor MDSCs, and describe new findings about immunosuppressive function of different subtypes of MDSCs in cancer. We also discussed tumor angiogenic activities and pro-tumor invasion/metastatic roles of MDSCs in tumor progression.

Chronic Inflammation-Related HPV: A Driving Force Speeds Oropharyngeal Carcinogenesis

Oropharyngeal squamous cell carcinoma (OPSCC) has been known to be a highly aggressive disease associated with human papilloma virus (HPV) infection. To investigate the relationship between HPV and chronic inflammation in oropharyngeal carcinogenesis, we collected 140 oral mucous fresh specimens including 50 OPSCC patients, 50 cancer in situ, 30 precancerous lesions, and 10 normal oral mucous. Our data demonstrated that there was a significantly higher proportion of severe chronic inflammation in dysplastic epithelia in comparison with that in normal tissues (P<0.001). The positive rate of HPV 16 was parallel with the chronic inflammation degrees from mild to severe inflammation (P<0.05). The positive rate of HPV 16 was progressively improved with the malignant progression of oral mucous (P<0.05). In addition, CD11b+ LIN- HLA-DR-CD33+ MDSCs were a critical cell population that mediates inflammation response and immune suppression in HPV-positive OPSCC. These indicated that persistent chronic inflammation-related HPV infection might drive oropharyngeal carcinogenesis and MDSCs might pay an important role during this process. Thus, a combination of HPV infection and inflammation expression might become a helpful biomedical marker to predict oropharyngeal carcinogenesis.

Progression of Large Lymphoma Is Significantly Impeded with a Combination of Gemcitabine Chemotherapy and Dendritic Cells Intra-Tumor Vaccination

Relapsed, refractory lymphoma remains to be a challenge and lacks efficient treatment. Some tumor cells escape from treatment, become resistant to chemotherapeutic agents, and rapidly regenerate into large tumors. Lymphoma cells induce accumulation of Gr-1⁺CD11b⁺ myeloid derived suppressor cells (MDSCs) in lymphatic organs and their vicinity. MDSCs enable tumor cells to escape from immune cells mediated surveillance and attack. Gemcitabine is a chemotherapeutic agent that eliminates both tumor cells and MDSCs, improving the immune environment favorable for subsequent treatment. We evaluated the effects of low dose gemcitabine combined with intra-tumorally delivered dendritic cells (DCs) for the treatment of A20 large-size lymphoma. We showed that MDSCs increased markedly in lymphoma-bearing mice, and that gemcitabine significantly increased the apoptosis of MDSCs. Treatment of lymphoma with either gemcitabine or intra-tumoral DCs alone could not inhibit tumor growth or rescue lymphoma-bearing mice. Treatment of lymphoma with small dose gemcitabine followed by intra-tumorally injected DCs significantly improved the efficacy of either individual treatment by reducing MDSCs, inducing onsite DCs maturation, eliminating tumor cells, inhibiting tumor growth and relapse, and extending the survival of the lymphoma-bearing mice, partly through the induction of the IFNγ secreting cells and the activation of cytotoxic lymphocytes. We showed that NK cells and CD8⁺ T cells were the major effectors to mediate the inhibition of tumor growth. Thus, the observation that gemcitabine synergizes DCs mediated immunotherapy to improve the efficacy of large size lymphoma treatment provides an experimental basis for the combination of chemotherapy and immunotherapy for the efficient treatment of relapsed or refractory lymphoma.

Immunosuppressive and Prometastatic Functions of Myeloid-Derived Suppressive Cells Rely upon Education from Tumor-Associated B Cells

Myeloid-derived suppressive cells (MDSC) have been reported to promote metastasis, but the loss of cancer-induced B cells/B regulatory cells (tBreg) can block metastasis despite MDSC expansion in cancer. Here, using multiple murine tumor models and human MDSC, we show that MDSC populations that expand in cancer have only partially primed regulatory function and limited prometastatic activity unless they are fully educated by tBregs. Cancer-induced tBregs directly activate the regulatory function of both the monocyte and granulocyte subpopulations of MDSC, relying, in part, on TgfβR1/TgfβR2 signaling. MDSC fully educated in this manner exhibit an increased production of reactive oxygen species and NO and more efficiently suppress CD4(+) and CD8(+) T cells, thereby promoting tumor growth and metastasis. Thus, loss of tBregs or TgfβR deficiency in MDSC is sufficient to disable their suppressive function and to block metastasis. Overall, our data indicate that cancer-induced B cells/B regulatory cells are important regulators of the immunosuppressive and prometastatic functions of MDSC.

Chemical compounds from anthropogenic environment and immune evasion mechanisms: potential interactions

An increasing number of studies suggest an important role of host immunity as a barrier to tumor formation and progression. Complex mechanisms and multiple pathways are involved in evading innate and adaptive immune responses, with a broad spectrum of chemicals displaying the potential to adversely influence immunosurveillance. The evaluation of the cumulative effects of low-dose exposures from the occupational and natural environment, especially if multiple chemicals target the same gene(s) or pathway(s), is a challenge. We reviewed common environmental chemicals and discussed their potential effects on immunosurveillance. Our overarching objective was to review related signaling pathways influencing immune surveillance such as the pathways involving PI3K/Akt, chemokines, TGF-β, FAK, IGF-1, HIF-1α, IL-6, IL-1α, CTLA-4 and PD-1/PDL-1 could individually or collectively impact immunosurveillance. A number of chemicals that are common in the anthropogenic environment such as fungicides (maneb, fluoxastrobin and pyroclostrobin), herbicides (atrazine), insecticides (pyridaben and azamethiphos), the components of personal care products (triclosan and bisphenol A) and diethylhexylphthalate with pathways critical to tumor immunosurveillance. At this time, these chemicals are not recognized as human carcinogens; however, it is known that they these chemicalscan simultaneously persist in the environment and appear to have some potential interfere with the host immune response, therefore potentially contributing to promotion interacting with of immune evasion mechanisms, and promoting subsequent tumor growth and progression.

Phenylhydrazine administration accelerates the development of experimental cerebral malaria

Phenylhydrazine (PHZ) treatment is generally used to enhance parasitemia in infected mice models. Transient reticulocytosis is commonly observed in iron-deficient anemic hosts after treatment with iron supplementation, and is also associated with short-term hemolysis caused by PHZ treatment. In this study, we investigated the relationship between reticulocytosis and cerebral malaria (CM) in a murine model induced by PHZ administration before Plasmodium berghei ANKA (PbA) infection. Mortality and parasitemia were checked daily. Pro-inflammatory cytokines and IL-10 were quantified by ELISA. The expression of CXCL9, CXCL10, CCL5, and CXCR3 mRNAs was determined by real-time PCR. Brain sequestration of CD4(+) and CD8(+) T cells and populations of splenic Th1 CD4(+) T cells, dendritic cells (DCs), CD11b(+) Gr1(+) cells, and regulatory T cells (Tregs) were assessed by FACS. PHZ administration dramatically increased parasitemia from day 3 to day 5 post infection (p.i.) compared with the untreated control infected mice group; also, CM developed at day 5 p.i., compared with day 7 p.i. in untreated control infected mice, as well as significantly decreased blood-brain barrier function (P < 0.001). PHZ administration during PbA infection significantly increased the expression of CXCL9 (P <0.05) and VCAM-1 (P <0.001) in the brain, increased the expression of CXCL10, CCL5 and CXCR3, and significantly increased the recruitment of CD4(+) and CD8(+) T cells (P <0.001 and P <0.01, respectively) as well as CD11b(+) Gr1(+) cells to the brain. In addition, PHZ administration significantly increased the numbers of IL-12-secreting DCs at days 3 and 5 p.i. compared to those of untreated control infected mice (P <0.001 and P <0.01, respectively). Consequently, the activation of CD4(+) T cells, especially the expansion of the Th1 subset (P <0.05), was significantly and dramatically enhanced and was accompanied by marked increases in the production of protein and/or mRNA of the Th1-type pro-inflammatory mediators, IFN-γ and TNF-α (P <0.01 for both for protein; P <0.05 for TNF-α mRNA). Our results suggest that, compared to healthy individuals, people suffering from reticulocytosis may be more susceptible to severe malaria infection in malaria endemic areas. This has implications for the most appropriate selection of treatment, which may also cause reticulocytosis in patients living in such areas.