CD200 and membrane protein interactions in the control of myeloid cells

Bioinformatic analysis of the role of immune checkpoint genes and immune infiltration in the pathogenesis and development of premature ovarian insufficiency

PURPOSE

With advances in immunology, increasing evidence suggests that immunity is involved in premature ovarian insufficiency (POI) pathogenesis. This study investigated the roles of immune checkpoint genes and immune cell infiltration in POI pathogenesis and development.

METHODS

The GSE39501 dataset and immune checkpoint genes were obtained from the Gene Expression Omnibus database and related literature. The two datasets were intersected to obtain immune checkpoint-related differentially expressed genes (ICRDEGs), which were analyzed using Gene Ontology and Kyoto Encyclopedia of Gene and Genomes enrichment analysis, weighted correlation network analysis, protein-protein interaction and related microRNAs, transcription factors, and RNA binding proteins. The immune cell infiltration of ICRDEGs was explored, and receiver operating characteristic curves were used to validate the diagnostic value of ICRDEGs in POI.

RESULTS

We performed ICRDEG functional enrichment analysis and found that these genes were closely related to immune processes, such as T cell activation. Specifically, they are enriched in various biological processes and pathways, such as cell adhesion molecule and T cell receptor signaling pathways. Weighted correlation network analysis identified seven hub genes: Cd200, Cd274, Cd28, neurociliary protein-1, Cd276, Cd40lg, and Cd47. Furthermore, we identified 112 microRNAs, 17 RNA-binding proteins, and 101 transcription factors. Finally, immune infiltration analysis showed a clear positive correlation between hub genes and multiple immune cell types.

CONCLUSION

Bioinformatic analysis identified seven potential ICRDEGs associated with POI, among which the immune checkpoint molecules CD200 and neurociliary protein-1 may be involved in the pathogenesis of POI.

Molecular incompatibility between pig CD200 and human CD200 receptor in in vitro xenogeneic immune responses

Overexpression of human CD200 (hCD200) in porcine endothelial cells (PECs) has been reported to suppress xenogeneic immune responses of human macrophages against porcine endothelial cells. The current study aimed to address whether the above-mentioned beneficial effect of hCD200 is mediated by overcoming the molecular incompatibility between porcine CD200 (pCD200) and hCD200 receptor or simply by increasing the expression levels of CD200 without any molecular incompatibility across the two species. We overexpressed hCD200 or pCD200 using lentiviral vectors with V5 marker in porcine endothelial cells and compared their suppressive activity against U937-derived human macrophage-like cells (hMCs) and primary macrophages. In xenogeneic coculture of porcine endothelial cells and human macrophage-like cells or macrophages, hCD200-porcine endothelial cells suppressed phagocytosis and cytotoxicity of human macrophages to a greater extent than pCD200-porcine endothelial cells. Secretion of tumor necrosis factor-α, interleukin-1β, and monocyte chemoattractant protein-1 from human macrophages and expression of M1 phenotypes (inducible nitric oxide synthase, dectin-1, and CD86) were also suppressed by hCD200 to a greater extent than pCD200. Furthermore, in signal transduction downstream of CD200 receptor, hCD200 induced Dok2 phosphorylation and suppressed IκB phosphorylation to a greater extent than pCD200. The above data supported the possibility of a significant molecular incompatibility between pCD200 and human CD200 receptor, suggesting that the beneficial effects of hCD200 overexpression in porcine endothelial cells could be mediated by overcoming the molecular incompatibility across the species barrier rather than by simple overexpression effects of CD200.

Microglia heterogeneity in health and disease

Microglia, the resident immune cells of the central nervous system (CNS), have received significant attention due to their critical roles in maintaining brain homeostasis and mediating cerebral immune responses. Understanding the origin of microglia has been a subject of great interest, and emerging evidence suggests that microglia consist of multiple subpopulations with unique molecular and functional characteristics. These subpopulations of microglia may exhibit specialized roles in response to different environmental cues as in disease conditions. The newfound understanding of microglial heterogeneity has significant implications for elucidating their roles in both physiological and pathological conditions. In the context of disease, microglia have been studied rigorously as they play a very important role in neuroinflammation. Dysregulated microglial activation and function contribute to chronic inflammation. Further exploration of microglial heterogeneity and their interactions with other cell types in the CNS will undoubtedly pave the way to novel therapeutic strategies targeting microglia-mediated pathologies. In this review, we discuss the latest advances in the field of microglia research, focusing specifically on the origin and subpopulations of microglia, the populations of microglia types in the brains of patients with neurodegenerative diseases, and how microglia are regulated in the healthy CNS.

Improving cancer immunotherapy by preventing cancer stem cell and immune cell linking in the tumor microenvironment

Cancer stem cells are the key link between malignant tumor progression and drug resistance. This cell population has special properties that are different from those of conventional tumor cells, and the role of cancer stem cell-related exosomes in progression of tumor malignancy is becoming increasingly clear. Cancer stem cell-derived exosomes carry a variety of functional molecules involved in regulation of the microenvironment, especially with regard to immune cells, but how these exosomes exert their functions and the specific mechanisms need to be further clarified. Here, we summarize the role of cancer stem cell exosomes in regulating immune cells in detail, aiming to provide new insights for subsequent targeted drug development and clinical strategy formulation.

The role of efferocytosis and transplant rejection: Strategies in promoting transplantation tolerance using apoptotic cell therapy and/or synthetic particles

Recently, efforts have been made to recognize the precise reason(s) for transplant failure and the process of rejection utilizing the molecular signature. Most transplant recipients do not appreciate the unknown length of survival of allogeneic grafts with the existing standard of care. Two noteworthy immunological pathways occur during allogeneic transplant rejection. A nonspecific innate immune response predominates in the early stages of the immune reaction, and allogeneic antigens initiate a donor-specific adaptive reaction. Though the adaptive response is the major cause of allograft rejection, earlier pro-inflammatory responses that are part of the innate immune response are also regarded as significant in graft loss. The onset of the innate and adaptive immune response causes chronic and acute transplant rejection. Currently employed immunosuppressive medications have shown little or no influence on chronic rejection and, as a result, on overall long-term transplant survival. Furthermore, long-term pharmaceutical immunosuppression is associated with side effects, toxicity, and an increased risk of developing diseases, both infectious and metabolic. As a result, there is a need for the development of innovative donor-specific immunosuppressive medications to regulate the allorecognition pathways that induce graft loss and to reduce the side effects of immunosuppression. Efferocytosis is an immunomodulatory mechanism with fast and efficient clearance of apoptotic cells (ACs). As such, AC therapy strategies have been suggested to limit transplant-related sequelae. Efferocytosis-based medicines/treatments can also decrease the use of immunosuppressive drugs and have no detrimental side effects. Thus, this review aims to investigate the impact of efferocytosis on transplant rejection/tolerance and identify approaches using AC clearance to increase transplant viability.

The kinetics of inhibitory immune checkpoints during and post-COVID-19: the knowns and unknowns

The immune system is tightly regulated to prevent immune reactions to self-antigens and to avoid excessive immune responses during and after challenges from non-self-antigens. Inhibitory immune checkpoints (IICPs), as the major regulators of immune system responses, are extremely important for maintaining the homeostasis of cells and tissues. However, the high and sustained co-expression of IICPs in chronic infections, under persistent antigenic stimulations, results in reduced immune cell functioning and more severe and prolonged disease complications. Furthermore, IICPs-mediated interactions can be hijacked by pathogens in order to evade immune induction or effector mechanisms. Therefore, IICPs can be potential targets for the prognosis and treatment of chronic infectious diseases. This is especially the case with regards to the most challenging infectious disease of recent times, coronavirus disease-2019 (COVID-19), whose long-term complications can persist long after recovery. This article reviews the current knowledge about the kinetics and functioning of the IICPs during and post-COVID-19.

Novel targets for immune-checkpoint inhibition in cancer

Immune-checkpoint inhibitors have revolutionized cancer therapy, yet many patients either do not derive any benefit from treatment or develop a resistance to checkpoint inhibitors. Intrinsic resistance can result from neoantigen depletion, defective antigen presentation, PD-L1 downregulation, immune-checkpoint ligand upregulation, immunosuppression, and tumor cell phenotypic changes. On the other hand, extrinsic resistance involves acquired upregulation of inhibitory immune-checkpoints, leading to T-cell exhaustion. Current data suggest that PD-1, CTLA-4, and LAG-3 upregulation limits the efficacy of single-agent immune-checkpoint inhibitors. Ongoing clinical trials are investigating novel immune-checkpoint targets to avoid or overcome resistance. This review provides an in-depth analysis of the evolving landscape of potentially targetable immune-checkpoints in cancer. We highlight their biology, emphasizing the current understanding of resistance mechanisms and focusing on promising strategies that are under investigation. We also summarize current results and ongoing clinical trials in this crucial field that could once again revolutionize outcomes for cancer patients.

Microglia Transcriptional Profiling in Major Depressive Disorder Shows Inhibition of Cortical Gray Matter Microglia

BACKGROUND

Microglia have been implicated in the pathophysiology of major depressive disorder (MDD), but information on biological mechanisms is limited. Therefore, we investigated the gene expression profile of microglial cells in relation to neuronal regulators of microglia activity in well-characterized MDD and control autopsy brains.

METHODS

Pure, intact microglia were isolated at brain autopsy from occipital cortex gray matter (GM) and corpus callosum white matter of 13 donors with MDD and 10 age-matched control donors for RNA sequencing. Top differentially expressed genes were validated using immunohistochemistry staining. Because gene expression changes were only detected in GM microglia, neuronal regulators of microglia were investigated in cortical tissue and synaptosomes from the cortex by reverse transcriptase-quantitative polymerase chain reaction and Western blot.

RESULTS

Transcriptome analysis revealed 92 genes differentially expressed in microglia isolated from GM, but none in microglia from white matter in donors with MDD, compared with control donors. Of these, 81 genes were less abundantly expressed in GM in MDD, including CD163, MKI67, SPP1, CD14, FCGR1A/C, and C1QA/B/C. Accordingly, pathways related to effector mechanisms, such as the complement system and phagocytosis, were differentially regulated in GM microglia in MDD. Immunohistochemistry staining revealed significantly lower expression of CD163 protein in MDD. Whole tissue analysis showed an increase in CD200 (p = .0009) and CD47 (p = .068) messenger RNA, and CD47 protein was significantly elevated (p = .0396) in synaptic fractions of MDD cases.

CONCLUSIONS

Transcriptional profiling indicates an immune-suppressed microglial phenotype in MDD that is possibly caused by neuronal regulation.

Emerging Immune Checkpoint Molecules on Cancer Cells: CD24 and CD200

Cancer immunotherapy strategies are based on the utilization of immune checkpoint inhibitors to instigate an antitumor immune response. The efficacy of immune checkpoint blockade, directed at adaptive immune checkpoints, has been demonstrated in select cancer types. However, only a limited subset of patients has exhibited definitive outcomes characterized by a sustained response after discontinuation of therapy. Recent investigations have highlighted the significance of immune checkpoint molecules that are overexpressed in cancer cells and inhibit myeloid lineage immune cells within a tumor microenvironment. These checkpoints are identified as potential targets for anticancer immune responses. Notably, the immune checkpoint molecules CD24 and CD200 have garnered attention owing to their involvement in tumor immune evasion. CD24 and CD200 are overexpressed across diverse cancer types and serve as signaling checkpoints by engaging their respective receptors, Siglec-10 and CD200 receptor, which are expressed on tumor-associated myeloid cells. In this review, we summarized and discussed the latest advancements and insights into CD24 and CD200 as emergent immune checkpoint moieties, further delving into their therapeutic potentials for cancer treatment.

Immune checkpoints represent a promising breakthrough in targeted therapy and prognosis of myelodysplastic syndrome

Myelodysplastic syndrome (MDS) is a hematological malignancy of undetermined etiology, possibly linked to chromosomal structural alterations, genetic mutations, presentation and carcinogenicity of variant antigens on cell surface, and the generation of pro-inflammatory microenvironment in the bone marrow. Current drugs are unable to cure this disease, and therefore, decreasing the survival and proliferation of malignant cells to delay disease progression and extend the survival time of patients becomes the primary approach to management. In recent years, the immune system has received increasing attention for its potential role in the occurrence and development of MDS, leading to the emergence of immunoregulation as a viable treatment option. The current review provides a brief overview of pathogenesis of MDS and current treatment principles. In the meantime, the significance of immune proteins in treatment and prognosis of MDS is also discussed.

Targeting phagocytosis to enhance antitumor immunity

Many patients with metastatic or treatment-resistant cancer have experienced improved outcomes after immunotherapy that targets adaptive immune checkpoints. However, innate immune checkpoints, which can hinder the detection and clearance of malignant cells, are also crucial in tumor-mediated immune escape and may also serve as targets in cancer immunotherapy. In this review, we discuss the current understanding of immune evasion by cancer cells via disruption of phagocytic clearance, and the potential effects of blocking phagocytosis checkpoints on the activation of antitumor immune responses. We propose that a more effective combination immunotherapy strategy could be to exploit tumor-intrinsic processes that inhibit key innate immune surveillance processes, such as phagocytosis, and incorporate both innate and adaptive immune responses for treating patients with cancer.

Moderate intrinsic phenotypic alterations in C9orf72 ALS/FTD iPSC-microglia despite the presence of C9orf72 pathological features

While motor and cortical neurons are affected in C9orf72 amyotrophic lateral sclerosis and frontotemporal dementia (ALS/FTD), it remains largely unknown if and how non-neuronal cells induce or exacerbate neuronal damage. We differentiated C9orf72 ALS/FTD patient-derived induced pluripotent stem cells into microglia (iPSC-MG) and examined their intrinsic phenotypes. Similar to iPSC motor neurons, C9orf72 ALS/FTD iPSC-MG mono-cultures form G4C2 repeat RNA foci, exhibit reduced C9orf72 protein levels, and generate dipeptide repeat proteins. Healthy control and C9orf72 ALS/FTD iPSC-MG equally express microglial specific genes and perform microglial functions, including inflammatory cytokine release and phagocytosis of extracellular cargos, such as synthetic amyloid beta peptides and healthy human brain synaptoneurosomes. RNA sequencing analysis revealed select transcriptional changes of genes associated with neuroinflammation or neurodegeneration in diseased microglia yet no significant differentially expressed microglial-enriched genes. Moderate molecular and functional differences were observed in C9orf72 iPSC-MG mono-cultures despite the presence of C9orf72 pathological features suggesting that a diseased microenvironment may be required to induce phenotypic changes in microglial cells and the associated neuronal dysfunction seen in C9orf72 ALS/FTD neurodegeneration.

GAS6 From CD200+ Adipose-Derived Stem Cells Mitigates Colonic Inflammation in a Macrophage-Dependent Manner

BACKGROUND AND AIMS

Stem cell therapy is a promising cell-based treatment modality for inflammatory bowel diseases [IBD], but its application is limited by the nature of cell heterogeneity.

METHODS

Single-cell RNA-sequencing was performed on the adipose-derived stem cells [ADSCs]. The in vitro immunomodulatory effect of ADSCs was evaluated by co-culturing with human CD4+ T cells or macrophages. The in vivo therapeutic value of ADSCs was assessed using a murine colitis model induced by dextran sulphate sodium [DSS] or 2,4,6-trinitrobenzene sulphonic acid [TNBS].

RESULTS

CD200+ ADSCs were identified as a novel subpopulation of ADSCs, based on gene ontology analysis of immunoregulatory functions. The immunoregulatory functions of these cells were further confirmed by co-culturing with CD4+ T cells or macrophages. Administration of CD200+ ADSCs effectively reduced intestinal inflammation in IBD mice models. Furthermore, we found CD200+ ADSCs-derived GAS6 exerted protective effects on experimental colitis by promoting macrophage M2 polarization via the Mer/PI3K/Akt/GSK3β signalling pathway.

CONCLUSIONS

This study uncovered the heterogeneity in ADSCs, in which CD200+ ADSCs presents as an alternative to conventional treatment of IBD.

The immunoregulatory protein CD200 as a potentially lucrative yet elusive target for cancer therapy

CD200 is an immunoregulatory cell surface ligand with proven pro-tumorigenic credentials via its ability to suppress CD200 receptor (CD200R)-expressing anti-tumor immune function. This definitive role for the CD200-CD200R axis in regulating an immunosuppressive tumor microenvironment has garnered increasing interest in CD200 as a candidate target for immune checkpoint inhibition therapy. However, while the CD200 blocking antibody samalizumab is still in the early stages of clinical testing, alternative mechanisms for the pro-tumorigenic role of CD200 have recently emerged that extend beyond direct suppression of anti-tumor T cell responses and, as such, may not be susceptible to CD200 antibody blockade. Herein, we will summarize the current understanding of CD200 expression and function in the tumor microenvironment as well as alternative strategies for potential neutralization of multiple CD200 mechanisms in human cancers.

Cancel cancer: The immunotherapeutic potential of CD200/CD200R blockade

Immune checkpoint molecules function to inhibit and regulate immune response pathways to prevent hyperactive immune activity from damaging healthy tissues. In cancer patients, targeting these key molecules may serve as a valuable therapeutic mechanism to bolster immune function and restore the body's natural defenses against tumors. CD200, an immune checkpoint molecule, is a surface glycoprotein that is widely but not ubiquitously expressed throughout the body. By interacting with its inhibitory receptor CD200R, CD200 suppresses immune cell activity within the tumor microenvironment, creating conditions that foster tumor growth. Targeting the CD200/CD200R pathway, either through the use of monoclonal antibodies or peptide inhibitors, has shown to be effective in boosting anti-tumor immune activity. This review will explore CD200 and the protein's expression and role within the tumor microenvironment, blood endothelial cells, and lymph nodes. This paper will also discuss the advantages and challenges of current strategies used to target CD200 and briefly summarize relevant preclinical/clinical studies investigating the immunotherapeutic efficacy of CD200/CD200R blockade.

Immunological Parameters in Patients Suffering from Atopic Dermatitis and Either Treated or Non-Treated with Dupilumab

OBJECTIVE

The aim of the study is to analyze the absolute count of leukocytes, neutrophils, monocytes, eosinophils, T cells, natural killer cells, B cells and to evaluate the expression of functionally important CD23 and CD200 molecules on B cells in patients suffering from atopic dermatitis (AD), (with and without dupilumab therapy).

MATERIALS AND METHODS

We examined 45 patients suffering from AD - 32 patients without dupilumab treatment (10 men, 22 women, average age 35.0 years), 13 patients with dupilumab treatment (7 men, 6 women, average age 43.4 years) and 30 healthy control (10 men, 20 women, average age 44.7 years). Immunophenotype was examined by flow cytometry (Navios Flow Cytometer - Beckman Coulter). The blood count was examined with a Sysmex XN 3000, Sysmex SP10, microscope DI60 for digital morphology evaluating cell division and microscope Olympus BX40. We compared the absolute count of leukocytes and their subsets, T cells (CD4, CD8), natural killers cells, absolute and relative count of B lymphocytes and expression of surface molecules CD23 and CD200 on B cells in AD patients and in control group. Non-parametric Kruskal-Wallis one-factor analysis of variance with post-hoc (follow-up multiple comparison) and Dunn's test with Bonferroni modification of significance level were used for statistical analysis.

RESULTS

We confirmed the significantly higher number of neutrophils, monocytes and eosinophils and higher expression of CD23 and CD200 on B cells in peripheral blood of AD patients (either with or without dupilumab) therapy. We demonstrated the lower number of CD8+ T cells.

CONCLUSION

We demonstrated the difference in the count of white blood cells populations in patients suffering from AD compared with healthy control. There were a differences in the expression of immunoregulatory molecules CD23 and CD200 on B cells in AD patients (either with or without dupilumab therapy) in comparison to healthy controls.

Circulating CD200 is increased in the secretory phase of women with endometriosis as is endometrial mRNA, and endometrial stromal cell CD200R1 is increased in spite of reduced mRNA

PROBLEM

Estrogen-dependent extrauterine implantation and growth of menstrual endometrial tissue affects roughly 10% of reproductive age women and depends on suppression of local innate immune defenses to prevent ectopic tissue rejection. Immunohistochemistry has shown the immune check-point inhibitor CD200 which can suppress rejection is expressed in eutopic endometrium and in ectopic deposits. Soluble CD200 accumulated in venules draining eutopic and ectopic endometrium of endometriosis cases in the secretory phase but not proliferative phase of the menstrual cycle, and should be increased in the circulation.

METHOD OF STUDY

Sera from endometriosis and non-endometriosis controls were tested by ELISA for CD200. Endometrial CD200, CD200R1 and CD200R2 mRNA in eutopic was quantified by RT-PCR and localized by in situ hybridization. CD200R1 protein was quantified by immunohistochemistry.

RESULTS

Secretory phase serum CD200 was elevated in women with endometriosis compared to controls. Serum CD200 correlated with matched endometrial CD200 mRNA levels. Expression of mRNA for CD200R1 which signals immune suppression was decreased whereas mRNA for the CD200R2 activating receptor was increased. In situ staining of CD200R1 and CD200R2 mRNA showed both receptors were expressed and the fraction of CD200R that is CD200R1 was reduced in secretory and menstrual phase endometriosis endometrium consistent with the RT-PCR result. By contrast, CD200R1 protein and CD200R1 fraction of total CD200R protein were increased in endometriosis.

CONCLUSIONS

Failure to suppress circulating CD200 levels in the secretory phase had an 87% specificity and 90% sensitivity for endometriosis. CD200 and increased CD200R1 expression may facilitate development of ectopic deposits by suppressing rejection mechanisms.

Single-cell RNA-sequence analysis of human bone marrow reveals new targets for isolation of skeletal stem cells using spherical nucleic acids

There is a wealth of data indicating human bone marrow contains skeletal stem cells (SSC) with the capacity for osteogenic, chondrogenic and adipogenic differentiation. However, current methods to isolate SSCs are restricted by the lack of a defined marker, limiting understanding of SSC fate, immunophenotype, function and clinical application. The current study applied single-cell RNA-sequencing to profile human adult bone marrow populations from 11 donors and identified novel targets for SSC enrichment. Spherical nucleic acids were used to detect these mRNA targets in SSCs. This methodology was able to rapidly isolate potential SSCs found at a frequency of <1 in 1,000,000 in human bone marrow, with the capacity for tri-lineage differentiation in vitro and ectopic bone formation in vivo. The current studies detail the development of a platform to advance SSC enrichment from human bone marrow, offering an invaluable resource for further SSC characterisation, with significant therapeutic impact therein.

Specificity of CD200/CD200R pathway in LPS-induced lung inflammation

Introduction

At lung mucosal surfaces, immune cells must initiate inflammatory response against pathogen without inducing tissue damage. Loss of this equilibrium can lead to acute respiratory distress syndrome (ARDS), a severe lung inflammatory disease characterized by excessive inflammation and dysregulation of anti-inflammatory pathways.

Methods

To investigate the role of anti-inflammatory pathway CD200/CD200R in lung inflammatory response, we administered LPS intratracheally in CD200 KO and wild type (WT) rats. Inflammation was evaluated using bronchoalveolar lavage (BAL) cellularity. Lung injury was measured by total protein level in BAL fluid, and levels of proinflammatory cytokines (TNF, IL-6) and chemokines (CXCL2, CCL2) were determined in BAL supernatants. In a second series of experiments, recombinant CD200Fc was administered to KO rats to restore the anti-inflammatory response.

Results

At baseline, CD200 KO rats did not show sign of inflammation, however KO rats had lower number of alveolar macrophages. In addition, LPS administration induced greater pulmonary edema in CD200 KO rats. This was accompanied with a higher recruitment of neutrophils as well as levels of TNF, IL-6, CXCL2, and CCL2 in BAL compared to WT rats. CD200Fc administration in KO rats reduced neutrophil accumulation and TNF and CXCL2 levels in BAL. Interestingly, the increased inflammatory response of CD200 KO rats could be attributed to greater activation potential of alveolar macrophages with higher levels of ERK and P-ERK MAPK.

Conclusion

This study shows that lung inflammatory response is exacerbated in absence of CD200 in an experimental model of ARDS in rats. In addition, CD200/CD200R pathway shows selective regulation of acute lung inflammation and cannot completely abrogate the complex LPS-induced inflammatory response. However, addition of CD200 agonist in a multi-target therapy strategy could have beneficial impacts.

Mechanism investigation and experiment validation of capsaicin on uterine corpus endometrial carcinoma

Background: Using bioinformatics analysis and experimental operations, we intend to analyze the potential mechanism of action of capsaicin target gene GATA1 in the treatment of uterine corpus endometrial carcinoma (UCEC) and develop a prognostic model for the disease to validate this model.

Methods: By obtaining capsaicin and UCEC-related DR-DEGs, the prognosis-related gene GATA1 was screened. The survival analysis was conducted via establishing high and low expression groups of GATA1. Whether the GATA1 could be an independent prognostic factor for UCEC, it was also validated. The therapeutic mechanism of capsaicin-related genes in UCEC was further investigated using enrichment analysis and immune methods as well as in combination with single-cell sequencing data. Finally, it was validated by cell experiments.

Results: GATA1, a high-risk gene associated with prognosis, was obtained by screening. Kaplan-Meier analysis showed that the survival of the high expression group was lower than that of low expression group. ROC curves showed that the prediction effect of the model was good and stable (1-year area under curve (AUC): 0.601; 2-years AUC: 0.575; 3-years AUC: 0.610). Independent prognosis analysis showed that the GATA1 can serve as an independent prognostic factor for UCEC. Enrichment analysis showed that “neuroactive Ligand - receptor interaction and TYPE I DIABETES MELLITUS” had a significant enrichment effect. Single-cell sequencing showed that the GATA1 was significantly expressed in mast cells. Cell experiments showed that the capsaicin significantly reduced the UCEC cell activity and migration ability, as well as inhibited the expression of GATA1.

Conclusion: This study suggests that the capsaicin has potential value and application prospect in the treatment of UCEC. It provides new genetic markers for the prognosis of UCEC patients.

Mathematical Modeling and Analysis of CD200-CD200R in Cancer Treatment

CD200 is a cell membrane protein that binds to its receptor, CD200 receptor (CD200R). The CD200 positive tumor cells inhibit the cellular functions of M1 and M2 macrophages and dendritic cells (DCs) through the CD200-CD200R complex, resulting in downregulation of Interleukin-10 and Interleukin-12 productions and affecting the activation of cytotoxic T lymphocytes. In this work, we provide two ordinary differential equation models, one complete model and one simplified model, to investigate how the binding affinities of CD200R and the populations of M1 and M2 macrophages affect the functions of the CD200-CD200R complex in tumor growth. Our simulations demonstrate that (i) the impact of the CD200-CD200R complex on tumor promotion or inhibition highly depends on the binding affinity of the CD200R on M2 macrophages and DCs to the CD200 on tumor cells, and (ii) a stronger binding affinity of the CD200R on M1 macrophages or DCs to the CD200 on tumor cells induces a higher tumor cell density in the CD200 positive tumor. Thus, the CD200 blockade would be an efficient treatment method in this case. Moreover, the simplified model shows that the binding affinity of CD200R on macrophages is the major factor to determine the treatment efficacy of CD200 blockade when the binding affinities of CD200R on M1 and M2 macrophages are significantly different to each other. On the other hand, both the binding affinity of CD200R and the population of macrophages are the major factors to determine the treatment efficacy of CD200 blockade when the binding affinities of CD200R on M1 and M2 macrophages are close to each other. We also analyze the simplified model to investigate the dynamics of the positive and trivial equilibria of the CD200 positive tumor case and the CD200 deficient tumor case. The bifurcation diagrams show that when M1 macrophages dominate the population, the tumor cell density of the CD200 positive tumor is higher than the one of CD200 deficient tumor. Moreover, the dynamics of tumor cell density change from tumor elimination to tumor persistence to oscillation, as the maximal proliferation rate of tumor cells increases.

Bovine Peripheral Blood Derived Lymphocyte Proteome and Secretome Show Divergent Reaction of Bovine Immune Phenotypes after Stimulation with Pokeweed Mitogen

We recently identified a deviant bovine immune phenotype characterized by hyperproliferation of lymphocytes after polyclonal stimulation. This phenotype was first discovered in dams that responded to PregSure BVD vaccination by producing pathological antibodies, triggering the fatal disease “bovine neonatal pancytopenia” in calves. The aim of the study was to gain deeper insights into molecular processes occurring in lymphocytes of immune phenotypes and the effect on their secretome after immune stimulation. Two discovery proteomic experiments were performed with unstimulated and Pokeweed Mitogen (PWM) stimulated lymphocytes, using label-free LC-MS/MS. In lymphocytes, 2447 proteins were quantified, and 1204 proteins were quantified in the secretome. Quantitative proteome analysis of immune deviant and control samples after PWM stimulation revealed clear differences. The increase in abundance of IL17A, IL17F, IL8, CCL5, LRRC59, and CLIC4 was higher in controls through mitogenic stimulation. In contrast, the abundance of IFNγ, IL2, IL2RA, CD83, and CD200 increased significantly more in immune deviant lymphocytes. Additional pathway enrichment analysis of differentially secreted proteins also yielded fundamental differences between the immune phenotypes. Our study provides a comprehensive dataset, which gives novel insights into proteome changes of lymphocytes from different bovine immune phenotypes. These differences point to the development of diverse immune responses of bovine immune phenotypes after immune stimulation.

Neuronal Glial Crosstalk: Specific and Shared Mechanisms in Alzheimer’s Disease

The human brain maintains billions of neurons functional across the lifespan of the individual. The glial, supportive cells of the brain are indispensable to neuron elasticity. They undergo various states (active, reactive, macrophage, primed, resting) and carefully impose either quick repair or the cleaning of injured neurons to avoid damage extension. Identifying the failure of these interactions involving the relation of the input of glial cells to the inception and/or progression of chronic neurodegenerative diseases (ND) is crucial in identifying therapeutic options, given the well-built neuro-immune module of these diseases. In the present review, we scrutinize different interactions and important factors including direct cell–cell contact, intervention by the CD200 system, various receptors present on their surfaces, CXC3RI and TREM2, and chemokines and cytokines with special reference to Alzheimer’s disease (AD). The present review of the available literature will elucidate the contribution of microglia and astrocytes to the pathophysiology of AD, thus evidencing glial cells as obligatory transducers of pathology and superlative targets for interference.

CD200R Combined Neutrophil-Lymphocyte Ratio Predict 90-Day Mortality in HBV-Related Acute-On-Chronic Liver Failure

Background: Survival of acute-on-chronic liver failure (ACLF) cannot be properly predicted based on clinical characteristics.

Aims: This study aimed to develop a predictive model to evaluating the prognosis for hepatitis B virus-related ACLF (HBV-ACLF) based on specific laboratory and immune indicators.

Methods: Baseline laboratory results were obtained and immune indicators were detected by flow cytometry. A predictive model, which estimates the prognosis at 90-day follow-up, was developed using data from a prospective study on 45 patients hospitalized of HBV-ACLF from June 2016 to April 2018 at the Beijing Ditan Hospital, Capital Medical University. The prognostic values of the predictive factors were determined by the area under the receiver operating characteristic (AUROC) curves.

Results: Six factors exhibited statistical differences between the survival and non-survival groups: proportions of CD4⁺T_N, CD4⁺T_EM, CD8⁺T_N, CD8⁺T_EM, CD200R⁺CD4⁺T cells and neutrophil-lymphocyte ratio (NLR). CD200R combined with the NLR had an AUROC of 0.916, which was significantly higher than the AUROC values of CD200R⁺CD4⁺T cells (0.868), NLR (0.761), model for end-stage liver disease (MELD) (0.840), MELD-Na (0.870), Child-Turcotte-Pugh (CTP) (0.580), or chronic liver failure-consortium ACLF (CLIF-C ACLF) score(0.840). At the cut-off point of−3.87, matching the maximum Youden index determined by ROC analysis, the positive predictive and negative predictive values for the mortality were 0.86 and 0.97, respectively.

Conclusions: The 90-day prediction model based on baseline levels of CD200R⁺CD4⁺T cells and NLR offers potential predictive value for the mortality of HBV-ACLF.

SIRPγ-CD47 Interaction Positively Regulates the Activation of Human T Cells in Situation of Chronic Stimulation

A numerous number of positive and negative signals via various molecules modulate T-cell activation. Within the various transmembrane proteins, SIRPγ is of interest since it is not expressed in rodents. SIRPγ interaction with CD47 is reevaluated in this study. Indeed, we show that the anti-SIRPγ mAb clone LSB2.20 previously used by others has not been appropriately characterized. We reveal that the anti-SIRPα clone KWAR23 is a Pan anti-SIRP mAb which efficiently blocks SIRPα and SIRPγ interactions with CD47. We show that SIRPγ expression on T cells varies with their differentiation and while being expressed on Tregs, is not implicated in their suppressive functions. SIRPγ spatial reorganization at the immune synapse is independent of its interaction with CD47. In vitro SIRPα-γ/CD47 blockade with KWAR23 impairs IFN-γ secretion by chronically activated T cells. In vivo in a xeno-GvHD model in NSG mice, the SIRPγ/CD47 blockade with the KWAR23 significantly delays the onset of the xeno-GvHD and deeply impairs human chimerism. In conclusion, we have shown that T-cell interaction with CD47 is of importance notably in chronic stimulation.

Immunohistochemical Expression of CD200 in Renal Cell Carcinoma

Background and Objectives:

Renal cell carcinoma (RCC) is the most common malignant renal neoplasm in adults. CD200 is a transmembrane protein and is a promising target for cancer immunotherapy. The aim of this study is to assess the CD200 expression in RCC.

Materials and Methods:

Eighty paraffin-embedded radical nephrectomy specimens, diagnosed with RCC were evaluated immunohistochemically for CD200 expression.

Results:

Out of eighty cases studied, CD200 was expressed in n = 73 cases (91.25%) with high intensity in 27 cases (33.75%), moderate intensity in 22 cases (27.5%), and mild intensity in 24 cases (30%). No staining was observed in the adjacent apparently normal renal tissue in all examined sections. No significant relationship was found between CD200 expression and the gender, tumor size, tumor side, histologic type, nuclear grade, T stage, and tumor necrosis.

Conclusion:

CD200 expression in most of the studied cases of RCC may refer to the potential therapeutic of anti-CD200 antibody for this cancer.

Regulation of the innate immune cells during pregnancy: An immune checkpoint perspective

The foetus can be regarded as a half‐allograft implanted into the maternal body. In a successful pregnancy, the mother does not reject the foetus because of the immune tolerance mechanism at the maternal‐foetal interface. The innate immune cells are a large part of the decidual leukocytes contributing significantly to a successful pregnancy. Although the contributions have been recognized, their role in human pregnancy has not been completely elucidated. Additionally, the accumulated evidence demonstrates that the immune checkpoint molecules expressed on the immune cells are co‐inhibitory receptors regulating their activation and biological function. Therefore, it is critical to understand the immune microenvironment and explore the function of the innate immune cells during pregnancy. This review summarizes the classic immune checkpoints such as PD‐1, CTLA‐4 and some novel molecules recently identified, including TIM‐3, CD200, TIGIT and the Siglecs family on the decidual and peripheral innate immune cells during pregnancy. Furthermore, it emphasizes the role of the immune checkpoint molecules in pregnancy‐associated complications and reproductive immunotherapy.

CD200 expression in hematopoietic neoplasms: Beyond a marker for diagnosis of B-cell neoplasms

CD200 (OX-2) is expressed in myeloid cells, B cells, subsets of T cells and on other normal and neoplastic non-hematopoietic cells. It interacts with CD200R and has a suppressive effect on T cells immune mediated response. We aimed to review CD200 expression and its role in the immune evasion of non-B cell hematopoietic neoplasms. In acute myeloid leukemia, CD200 seems to be related to the worst outcome, even in diseases of good prognosis, possibly due to an immunosuppressive effect. In plasma cell myeloma studies, while some have associated CD200 expression with worst prognosis possibly due to its suppressive effect on monocyte and T cell-mediated immune response, in others CD200 appeared to be a marker of a better outcome, or even showed no impact in event-free survival (EFS). Few studies have evaluated CD200 expression in T cell neoplasms; however, it appears to be a good immunophenotypic marker for angioimmunoblastic T cell lymphoma. In conclusion, CD200 appears to be involved in the immune evasion of malignant cells, which could affect the survival of these patients.

Overexpression of CD200 is a Stem Cell-Specific Mechanism of Immune Evasion in AML

BACKGROUND

Acute myeloid leukemia (AML) stem cells (LSCs) are capable of surviving current standard chemotherapy and are the likely source of deadly, relapsed disease. While stem cell transplant serves as proof-of-principle that AML LSCs can be eliminated by the immune system, the translation of existing immunotherapies to AML has been met with limited success. Consequently, understanding and exploiting the unique immune-evasive mechanisms of AML LSCs is critical.

METHODS

Analysis of stem cell datasets and primary patient samples revealed CD200 as a putative stem cell-specific immune checkpoint overexpressed in AML LSCs. Isogenic cell line models of CD200 expression were employed to characterize the interaction of CD200⁺ AML with various immune cell subsets both in vitro and in peripheral blood mononuclear cell (PBMC)-humanized mouse models. CyTOF and RNA-sequencing were performed on humanized mice to identify novel mechanisms of CD200-mediated immunosuppression. To clinically translate these findings, we developed a fully humanized CD200 antibody (IgG1) that removed the immunosuppressive signal by blocking interaction with the CD200 receptor while also inducing a potent Fc-mediated response. Therapeutic efficacy of the CD200 antibody was evaluated using both humanized mice and patient-derived xenograft models.

RESULTS

Our results demonstrate that CD200 is selectively overexpressed in AML LSCs and is broadly immunosuppressive by impairing cytokine secretion in both innate and adaptive immune cell subsets. In a PBMC-humanized mouse model, CD200⁺ leukemia progressed rapidly, escaping elimination by T cells, compared with CD200^- AML. T cells from mice with CD200⁺ AML were characterized by an abundance of metabolically quiescent CD8⁺ central and effector memory cells. Mechanistically, CD200 expression on AML cells significantly impaired OXPHOS metabolic activity in T cells from healthy donors. Importantly, CD200 antibody therapy could eliminate disease in the presence of graft-versus-leukemia in immune competent mice and could significantly improve the efficacy of low-intensity azacitidine/venetoclax chemotherapy in immunodeficient hosts.

CONCLUSIONS

Overexpression of CD200 is a stem cell-specific marker that contributes to immunosuppression in AML by impairing effector cell metabolism and function. CD200 antibody therapy is capable of simultaneously reducing CD200-mediated suppression while also engaging macrophage activity. This study lays the groundwork for CD200-targeted therapeutic strategies to eliminate LSCs and prevent AML relapse.

The CD200-CD200R axis promotes squamous cell carcinoma metastasis via regulation of cathepsin K

The CD200-CD200R immunoregulatory signaling axis plays an etiological role in the survival and spread of numerous cancers primarily through suppression of anti-tumor immune surveillance. Our previous work outlined a pro-metastatic role for the CD200-CD200R axis in cutaneous squamous cell carcinoma (cSCC) that is independent of direct T cell suppression but modulates the function of infiltrating myeloid cells. To identify effectors of the CD200-CD200R axis important for cSCC metastasis, we conducted RNA-Seq profiling of infiltrating CD11B+Cd200R+ cells isolated from CD200+ versus CD200-null cSCCs and identified the cysteine protease cathepsin K (Ctsk) to be highly upregulated in CD200+ cSCCs. CD11B+Cd200R+ cells expressed phenotypic markers associated with myeloid-derived suppressor cell-like cells and tumor-associated macrophages and were the primary source of Ctsk expression in cSCC. A Cd200R+ myeloid cell-cSCC co-culture system showed that induction of Ctsk was dependent on engagement of the CD200-CD200R axis, indicating that Ctsk is a target gene of this pathway in the cSCC tumor microenvironment. Inhibition of Ctsk, but not matrix metalloproteinases (MMP), significantly blocked cSCC cell migration in vitro. Finally, targeted CD200 disruption in tumor cells and Ctsk pharmacological inhibition significantly reduced cSCC metastasis in vivo. Collectively, these findings support the conclusion that CD200 stimulates cSCC invasion and metastasis via induction of Ctsk in CD200R+ infiltrating myeloid cells.

The Phagocytic Code Regulating Phagocytosis of Mammalian Cells

Mammalian phagocytes can phagocytose (i.e. eat) other mammalian cells in the body if they display certain signals, and this phagocytosis plays fundamental roles in development, cell turnover, tissue homeostasis and disease prevention. To phagocytose the correct cells, phagocytes must discriminate which cells to eat using a 'phagocytic code' - a set of over 50 known phagocytic signals determining whether a cell is eaten or not - comprising find-me signals, eat-me signals, don't-eat-me signals and opsonins. Most opsonins require binding to eat-me signals - for example, the opsonins galectin-3, calreticulin and C1q bind asialoglycan eat-me signals on target cells - to induce phagocytosis. Some proteins act as 'self-opsonins', while others are 'negative opsonins' or 'phagocyte suppressants', inhibiting phagocytosis. We review known phagocytic signals here, both established and novel, and how they integrate to regulate phagocytosis of several mammalian targets - including excess cells in development, senescent and aged cells, infected cells, cancer cells, dead or dying cells, cell debris and neuronal synapses. Understanding the phagocytic code, and how it goes wrong, may enable novel therapies for multiple pathologies with too much or too little phagocytosis, such as: infectious disease, cancer, neurodegeneration, psychiatric disease, cardiovascular disease, ageing and auto-immune disease.

CD200 expression marks leukemia stem cells in human AML

The leukemia stem cell (LSC) populations of acute myeloid leukemia (AML) exhibit phenotypic, genetic, and functional heterogeneity that contribute to therapy failure and relapse. Progress toward understanding the mechanistic basis for therapy resistance in LSCs has been hampered by difficulties in isolating cell fractions that enrich for the entire heterogeneous population of LSCs within individual AML samples. We previously reported that CD200 gene expression is upregulated in LSC-containing AML fractions. Here, we show that CD200 is present on a greater proportion of CD45dim blasts compared with more differentiated CD45high cells in AML patient samples. In 75% (49 of 65) of AML cases we examined, CD200 was expressed on ≥10% of CD45dim blasts; of these, CD200 identified LSCs within the blast population in 9 of 10 (90%) samples tested in xenotransplantation assays. CD200+ LSCs could be isolated from CD200+ normal HSCs with the use of additional markers. Notably, CD200 expression captured both CD34- and CD34+ LSCs within individual AML samples. Analysis of highly purified CD200+ LSC-containing fractions from NPM1-mutated AMLs, which are commonly CD34-, exhibited an enrichment of primitive gene expression signatures compared with unfractionated cells. Overall, our findings support CD200 as a novel LSC marker that is able to capture the entire LSC compartment from AML patient samples, including those with NPM1 mutation.

An emerging role for microglia in stress‐effects on memory

Stressful experiences evoke, among others, a rapid increase in brain (nor)epinephrine (NE) levels and a slower increase in glucocorticoid hormones (GCs) in the brain. Microglia are key regulators of neuronal function and contain receptors for NE and GCs. These brain cells may therefore potentially be involved in modulating stress effects on neuronal function and learning and memory. In this review, we discuss that stress induces (1) an increase in microglial numbers as well as (2) a shift toward a pro‐inflammatory profile. These microglia have (3) impaired crosstalk with neurons and (4) disrupted glutamate signaling. Moreover, microglial immune responses after stress (5) alter the kynurenine pathway through metabolites that impair glutamatergic transmission. All these effects could be involved in the impairments in memory and in synaptic plasticity caused by (prolonged) stress, implicating microglia as a potential novel target in stress‐related memory impairments.

Use of an anti-CD200-blocking antibody improves immune responses to AML in vitro and in vivo

Treatment of relapsed/resistant acute myeloid leukaemia (AML) remains a significant area of unmet patient need, the outlook for most patients remaining extremely poor. A promising approach is to augment the anti-tumour immune response in these patients; most cancers do not activate immune effector cells because they express immunosuppressive ligands. We have previously shown that CD200 (an immunosuppressive ligand) is overexpressed in AML and confers an inferior overall survival compared to CD200low/neg patients. Here we show that a fully human anti-CD200 antibody (TTI-CD200) can block the interaction of CD200 with its receptor and restore AML immune responses in vitro and in vivo.

Identification and Validation of a Tumor Microenvironment-Related Gene Signature for Prognostic Prediction in Advanced-Stage Non-Small-Cell Lung Cancer

The development of immunotherapy has greatly changed the advanced-stage non-small-cell lung cancer (NSCLC) treatment landscape. The complexity and heterogeneity of tumor microenvironment (TME) lead to discrepant immunotherapy effects among patients at the same pathologic stages. This study is aimed at exploring potential biomarkers of immunotherapy and accurately predicting the prognosis for advanced NSCLC patients. RNA-seq data and clinical information on stage III/IV NSCLC were obtained from The Cancer Genome Atlas (TCGA) and Gene Expression Omnibus (GEO). In TCGA-NSCLC with stage III/IV (n = 192), immune scores and stromal scores were calculated by using the ESTIMATE algorithms. Univariate, LASSO, and multivariate Cox regression analyses were performed to screen prognostic TME-related genes (TMERGs) and constructed a gene signature risk score model. It was validated in external dataset including GSE41271 (n = 91) and GSE81089 (n = 36). Additionally, a nomogram incorporating TMERG signature risk score and clinical characteristics was established. Further, we accessed the proportion of 22 types of tumor-infiltrating immune cells (TIIC) from the CIBERSORT website and analyzed the difference between two risk groups. OS of patients with high immune/stromal scores were higher (log-rank P = 0.044/log-rank P = 0.048). Multivariate Cox regression identified six prognostic TMERGs, including CD200, CHI3L2, CNTN1, CTSL, FYB1, and SLC52A1. We developed a six-gene risk score model, which was validated as an independent prognostic factor for OS (HR: 3.32, 95% CI: 2.16-5.09). Time-ROC curves showed useful discrimination for TCGA-NSCLC cohort (1-, 2-, and 3-year AUCs were 0.718, 0.761, and 0.750). The predictive robustness was validated in the external dataset. The C-index and 1-, 2-, and 3-year AUCs of nomogram were the largest, which demonstrated the nomogram had the greatest predictive accuracy and effectiveness and could be used for clinical guidance. Besides, the increased infiltration of T cells regulatory (Tregs) and macrophages M2 in the high-risk group suggested that chronic inflammation may reduce survival probability in patients with advanced NSCLC. We conducted a comprehensive analysis of the tumor microenvironment and identified the TMERG signature, which could predict prognosis accurately and provide a reference for the personalized immunotherapy for advanced NSCLC patients.

Distinct immune regulatory receptor profiles linked to altered monocyte subsets in sarcoidosis

Background

In sarcoidosis, blood monocytes, circulating precursors of granuloma macrophages, display enhanced inflammatory cytokine production, reduced expression of the regulatory (inhibitory) receptor CD200R, and altered subsets defined by CD14 and CD16. Regulatory receptors serve to dampen monocyte and macrophage inflammatory responses. We investigated the relationship between monocyte subsets and regulatory receptor expression in sarcoidosis.

Methods

Multiparameter flow cytometry was used to perform detailed analyses of cell surface regulatory molecules on freshly isolated blood immune cells from patients with chronic pulmonary sarcoidosis and age-matched healthy controls.

Results

25 patients with chronic pulmonary sarcoidosis (median duration of disease 22 months) who were not taking oral corticosteroids or other immunomodulators were recruited. Nonclassical monocytes were expanded in sarcoidosis and exhibited significantly lower expression of regulatory receptors CD200R, signal regulatory protein-α and CD47 than classical or intermediate monocytes. In sarcoidosis, all three monocyte subsets had significantly reduced CD200R and CD47 expression compared with healthy controls. A dichotomous distribution of CD200R was seen on classical and intermediate monocytes in the sarcoidosis population, with 14 out of 25 (56%) sarcoidosis patients having a CD200R^low phenotype and 11 out of 25 (44%) having a CD200R^high phenotype. These distinct sarcoidosis monocyte phenotypes remained consistent over time.

Conclusions

Nonclassical monocytes, which are expanded in sarcoidosis, express very low levels of regulatory receptors. Two distinct and persistent phenotypes of CD200R expression in classical and intermediate monocytes could be evaluated as sarcoidosis biomarkers.

Nonclassical monocytes, which are expanded in sarcoidosis, express very low levels of regulatory receptors. Two distinct and persistent phenotypes of CD200R expression in classical and intermediate monocytes could be evaluated as sarcoidosis biomarkers.https://bit.ly/2W0idAX

Immune evasion by cancer stem cells

Tumor immunity represents a new avenue for cancer therapy. Immune checkpoint inhibitors have successfully improved outcomes in several tumor types. In addition, currently, immune cell-based therapy is also attracting significant attention. However, the clinical efficacy of these treatments requires further improvement. The mechanisms through which cancer cells escape the immune response must be identified and clarified. Cancer stem cells (CSCs) play a central role in multiple aspects of malignant tumors. CSCs can initiate tumors in partially immunocompromised mice, whereas non-CSCs fail to form tumors, suggesting that tumor initiation is a definitive function of CSCs. However, the fact that non-CSCs also initiate tumors in more highly immunocompromised mice suggests that the immune evasion property may be a more fundamental feature of CSCs rather than a tumor-initiating property. In this review, we summarize studies that have elucidated how CSCs evade tumor immunity and create an immunosuppressive milieu with a focus on CSC-specific characteristics and functions. These profound mechanisms provide important clues for the development of novel tumor immunotherapies.

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Cancer stem cells (CSCs) play a central role in multiple aspects of malignant tumors.

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Immune evasion is a fundamental feature of CSCs.

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Immune evasion mechanisms must be precisely clarified to improve tumor immunotherapy.

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CSCs are promising targets for tumor immunotherapy.

Quantitative Assessment of CD200 and CD200R Expression in Lung Cancer

CD200/CD200R is an immune checkpoint with broad expression patterns and a potential target for immune therapy. In this study, we assess both CD200 and CD200R expression in solid tumors, with a focus on lung cancer, and evaluate their association with clinicopathologic characteristics, mutation status, outcome, and programmed death-ligand 1 (PD-L1) expression. We used multiplexed quantitative immunofluorescence (QIF) to measure the expression of CD200 and CD200R in a total of 455 patients from three lung cancer cohorts. Using carefully validated antibodies, we performed target measurement with tyramide-based QIF panels and analyzed the data using the PM2000 microscope and AQUA software. CD200 tumor positivity was found in 29.7% of non-small cell lung cancer (NSCLC) patients and 33.3% of lung large cell neuroendocrine carcinoma (LCNEC) patients. CD200 demonstrated notable intratumoral heterogeneity. CD200R was expressed in immune cells in 25% of NSCLC and 41.3% of LCNEC patients. While CD200R is predominantly expressed in immune cells, rare tumor cell staining was seen in a highly heterogeneous pattern. CD200R expression in the stromal compartment was significantly higher in patients with squamous differentiation (p < 0.0001). Neither CD200 nor CD200R were associated with other clinicopathologic characteristics or mutation status. Both biomarkers were not prognostic for disease-free or overall survival in NSCLC. CD200 showed moderate correlation with PD-L1. CD200/CD200R pathway is frequently expressed in lung cancer patients. Differential expression patterns of CD200 and CD200R with PD-L1 suggest a potential role for targeting this pathway alone in patients with NSCLC.

CD200:CD200R Interactions and Their Importance in Immunoregulation

The molecule CD200, described many years ago as a naturally occurring immunomodulatory agent, capable of regulating inflammation and transplant rejection, has attracted additional interest over the past years with the realization that it may also serve as an important marker for progressive malignancy. A large body of evidence also supports the hypothesis that this molecule can contribute to immunoregulation of, among other diseases, infection, autoimmune disease and allergy. New data have also come to light to characterize the receptors for CD200 (CD200R) and their potential mechanism(s) of action at the biochemical level, as well as the description of a novel natural antagonist of CD200, lacking the NH₂-terminal region of the full-length molecule. Significant controversies exist concerning the relative importance of CD200 as a ligand for all reported CD200Rs. Nevertheless, some progress has been made in the identification of the structural constraints determining the interaction between CD200 and CD200R, and this information has in turn proved of use in developing novel small molecule agonists/antagonists of the interaction. The review below highlights many of these newer findings, and attempts to place them in the broad context of our understanding of the role of CD200-CD200R interactions in a variety of human diseases.

Endocannabinoid Signaling for GABAergic-Microglia (Mis)Communication in the Brain Aging

The aging brain seems to be characterized by neuronal loss leading to cognitive decline and progressively worsening symptoms related to neurodegeneration. Also, pro-inflammatory states, if prolonged, may increase neuronal vulnerability via excessive activation of microglia and their pro-inflammatory by-products, which is seen as individuals increase in age. Consequently, microglial activity is tightly regulated by neuron-microglia communications. The endocannabinoid system (ECS) is emerging as a regulator of microglia and the neuronal-microglia communication system. Recently, it has been demonstrated that cannabinoid 1 (CB1) receptor signaling on GABAergic interneurons plays a crucial role in regulating microglial activity. Interestingly, if endocannabinoid signaling on GABAergic neurons are disturbed, the phenotypes mimic central nervous system insult models by activating microglia and leading to accelerated brain aging. Investigating the endocannabinoid receptors, ligands, and genetic deletions yields the potential to understand the communication system and mechanism by which the ECS regulates glial cells and aspects of aging. While there remains much to discover with the ECS, the information gathered and identified already could lead to the development of cell-specific therapeutic interventions that help in reducing the effects of age-related pro-inflammatory states and neurodegeneration.

CD200 Change Is Involved in Neuronal Death in Gerbil Hippocampal CA1 Field Following Transient Forebrain Ischemia and Postischemic Treatment with Risperidone Displays Neuroprotection without CD200 Change

It has been reported that CD200 (Cluster of Differentiation 200), expressed in neurons, regulates microglial activation in the central nervous system, and a decrease in CD200 expression causes an increase in microglial activation and neuronal loss. The aim of this study was to investigate time-dependent changes in CD200 expression in the hippocampus proper (CA1, 2, and 3 fields) after transient forebrain ischemia for 5 min in gerbils. In this study, 5-min ischemia evoked neuronal death (loss) of pyramidal neurons in the CA1 field, but not in the CA2/3 fields, at 5 days postischemia. In the sham group, CD200 expression was found in pyramidal neurons of the CA1 field, and the immunoreactivity in the group with ischemia was decreased at 6 h postischemia, dramatically increased at 12 h postischemia, decreased (to level found at 6 h postischemia) at 1 and 2 days postischemia, and significantly increased again at 5 days postischemia. At 5 days postischemia, CD200 immunoreactivity was strongly expressed in microglia and GABAergic neurons. However, in the CA3 field, the change in CD200 immunoreactivity in pyramidal neurons was markedly weaker than that in the CA1 field, showing there was no expression of CD 200 in microglia and GABAergic neurons. In addition, treatment of 10 mg/kg risperidone (an atypical antipsychotic drug) after the ischemia hardly changed CD200 immunoreactivity in the CA1 field, showing that CA1 pyramidal neurons were protected from the ischemic injury. These results indicate that the transient ischemia-induced change in CD200 expression may be associated with specific and selective neuronal death in the hippocampal CA1 field following transient forebrain ischemia.

Clinical significance of CD200 expression in newly diagnosed multiple myeloma patients and dynamic changing during treatment

The aim of our study was to determine the impact of CD200 expression in newly diagnosed myltiple myeloma (MM) patients. CD200⁺ patients had significantly shorter median overall survival time (OS) than CD200^- patients (41.0 months vs. not reached, p = .009). The ratio of CD4⁺ to CD8⁺ T cells was lower in CD200⁺ patients and this reduction was significantly related to the increase of CD8⁺ T cells (p = .021). Moreover, we analyzed dynamic changes of CD200 expression in 47 CD200⁺ patients during treatment. Thirty-eight (80.9%) patients switched to CD200^- during treatment. Those patients had a favorable survival compared with the others (median OS, 65.0 vs. 32.0 months, p < .001; median PFS, 29.0 vs. 11.5 months, p = .027). We concluded that CD200 expression is an independent marker for MM prognostic estimation during treatment.

Association of CD200 expression in paternal lymphocytes with female Th1/Th2 balance and pregnancy establishment at immunotherapy of recurrent spontaneous abortion

PROBLEM

We hypothesized that expression of transmembrane glycoprotein CD200 on paternal lymphocytes used for pre-gestational lymphocyte immunotherapy (LIT) of recurrent spontaneous abortion (RSA) can suppress the pro-inflammatory Th1-type immunity required for successful implantation. To reveal the association between CD200 expression, female immune background after LIT, and pregnancy establishment, we have performed this work.

METHOD OF STUDY

Pre-gestational alloimmunizations were given to 37 women using paternal peripheral blood leukocytes, combined with additional alloimmunizations in case of pregnancy. Lymphocyte phenotypes were determined by flow cytometry. Cytokines produced by mitogen-stimulated female peripheral blood cells were estimated by FlowCytomix™ technology.

RESULTS

We have shown that 78.4% (29/37) of women became pregnant within 12 menstrual cycles after pre-gestational LIT. Pregnancy establishment depends on the intensity of CD200 expression, which is significantly higher on the CD200⁺ lymphocytes administered to women who later did not achieve pregnancy (P < .05). The expression of CD200 negatively correlates with the ratios of Th1/Th2 cytokines produced by female peripheral blood cells (P < .05) and positively correlates with the frequency of female circulating regulatory T cells after LIT (P < .05). The ROC analysis showed that the intensity of CD200 expression and the Th1/Th2 ratios are the significant predictors of pregnancy establishment after pre-gestational LIT (P < .05 and P < .01, respectively).

CONCLUSION

Elevated CD200 expression on allogeneic lymphocytes most likely suppresses the pro-inflammatory Th1-type immunity needed for successful embryo implantation. Therefore, a personalized approach of LIT should be applied to avoid negative effects of such immunomodulation on pregnancy establishment.

Integrative Analysis of Cell Crosstalk within Follicular Lymphoma Cell Niche: Towards a Definition of the FL Supportive Synapse

Simple Summary

Follicular lymphoma, the most frequent indolent non-Hodgkin’s B cell lymphoma, arises from a germinal center B cell proliferation supported by a multidirectional crosstalk with the tumor microenvironment, in particular with follicular helper T cells and mesenchymal stromal cells. Here, we explored this complex network, starting from a comparative analysis of the molecular signatures of B cells, T cells, and stromal cells obtained from normal versus lymphoma tissues, and focusing on deregulated genes reflecting the crosstalk between these three cell subsets organizing the lymphoma cell niche. This helps us to point out new lymphoma-specific pathways, related to transcriptomic and functional specific features of T and stromal cells, and contributing to tumor B cell support directly or through the recruitment and/or activation of other pro-tumoral cell components. In the future, targeting these cell interactions with specific drugs in the FL niche could represent an attractive option for novel therapeutic strategies.

Abstract

Follicular lymphoma (FL), the most frequent indolent non-Hodgkin’s B cell lymphoma, is considered as a prototypical centrocyte-derived lymphoma, dependent on a specific microenvironment mimicking the normal germinal center (GC). In agreement, several FL genetic alterations affect the crosstalk between malignant B cells and surrounding cells, including stromal cells and follicular helper T cells (Tfh). In our study, we sought to deconvolute this complex FL supportive synapse by comparing the transcriptomic profiles of GC B cells, Tfh, and stromal cells, isolated from normal versus FL tissues, in order to identify tumor-specific pathways. In particular, we highlighted a high expression of IL-6 and IL-7 in FL B cells that could favor the activation of FL Tfh overexpressing IFNG, able in turn to stimulate FL B cells without triggering MHC (major histocompatibility) class II expression. Moreover, the glycoprotein clusterin was found up-regulated in FL stromal cells and could promote FL B cell adhesion. Finally, besides its expression on Tfh, CD200 was found overexpressed on tumor B cells and could contribute to the induction of the immunosuppressive enzyme indoleamine-2,3 dioxygenase by CD200R-expressing dendritic cells. Altogether our findings led us to outline the contribution of major signals provided by the FL microenvironment and their interactions with malignant FL B cells.

Smoking and Endothelial Dysfunction

Cigarette smoking is one of the most important health concerns worldwide. Even though the rate of smoking is declining in developed countries, it is still experiencing growth in developing regions. Many studies have examined the relationship between smoking, as an established risk factor, and cardiovascular diseases. We provide an updated review of the underlying mechanisms of smokinginduced cardiovascular diseases, with a focus on the relationship between smoking and oxidative stress, particularly from the perspective of endothelial cell dysfunction. We review smoking-induced oxidative stress as a trigger for a generalized vascular inflammation associated with cytokine release, adhesion of inflammatory cells and, ultimately, disruption of endothelial integrity as a protective barrier layer. We also briefly discuss the harms related to the vaping of electronic cigarettes, which many erroneously consider as a safe alternative to smoking. We conclude that even though e-cigarette could be a helpful device during the transition period of cigarette quitting, it is by no means a safe substitute.

Increased CD200 expression in post-transplant lymphoproliferative disorders correlates with an increased frequency of FoxP3(+) regulatory T cells

CD200 is a membrane protein with immunosuppressive function and is expressed in many hematopoietic neoplasms, including acute myeloid leukemia (AML), plasma cell myeloma (PCM), and B-cell lymphoproliferative disorders, but is mostly negative in diffuse large cell lymphoma (DLBCL). CD200 has been shown to be a poor prognostic marker in AML and PCM; in AML, its immunomodulatory effect was linked to its ability to induce FoxP3(+) regulatory T cells (Tregs). Post-transplant lymphoproliferative disorders (PTLDs) arise in the setting of immune dysregulation, and tumor-infiltrating T cells, including Tregs, have been shown to correlate with outcome in these disorders. Because there is no literature data and CD200 is a potentially useful diagnostic and prognostic marker, we studied the expression of CD200 in a series of 38 PTLDs by immunohistochemistry (ICH), and found that 23.7% PTLDs were CD200(+) and showed strong membrane and cytoplasmic positivity in the neoplastic cells. All CD200(+) monomorphic PTLDs were DLBCLs and the median FoxP3(+) Treg count/hpf was higher in CD200(+) than in CD200(-) PTLDs: 22.6 vs. 0.30 (p < 0.001). These results indicated that almost a quarter of PTLDs in our series are CD200(+) by IHC, and CD200 expression correlates with the frequency of immunosuppressive Tregs. This is novel data and supports a pathophysiologic link between CD200 activity and Tregs. In our series, the 5-year overall survival was shorter in CD200(+) PTLDs, compared to CD200(-) patients, although this difference did not reach statistical significance. In addition, we find a higher proportion of CD200(+) monomorphic PTLD-DLBCLs (31.0%), as compared to de novo DLBCLs (7-8%, as found here and in other studies). This may indicate differential expression of CD200 in B-cell lymphomas arising in the setting of immune dysregulation, and raises the possibility of anti-CD200 immunotherapy for these cases.

Host Transcriptional Response to Persistent Infection with a Live-Attenuated Porcine Reproductive and Respiratory Syndrome Virus Strain

Both virulent and live-attenuated porcine reproductive and respiratory syndrome virus (PRRSV) strains can establish persistent infection in lymphoid tissues of pigs. To investigate the mechanisms of PRRSV persistence, we performed a transcriptional analysis of inguinal lymphoid tissue collected from pigs experimentally infected with an attenuated PRRSV strain at 46 days post infection. A total of 6404 differentially expressed genes (DEGs) were detected of which 3960 DEGs were upregulated and 2444 DEGs were downregulated. Specifically, genes involved in innate immune responses and chemokines and receptors associated with T-cell homing to lymphoid tissues were down regulated. As a result, homing of virus-specific T-cells to lymphoid tissues seems to be ineffective, evidenced by the lower frequencies of virus-specific T-cell in lymphoid tissue than in peripheral blood. Genes associated with T-cell exhaustion were upregulated. Likewise, genes involved in the anti-apoptotic pathway were upregulated. Collectively, the data suggested that the live-attenuated PRRSV strain establishes a pro-survival microenvironment in lymphoid tissue by suppressing innate immune responses, T-cell homing, and preventing cell apoptosis.

Shifting equilibriums in Alzheimer's disease: the complex roles of microglia in neuroinflammation, neuronal survival and neurogenesis

Alzheimer's disease is the leading cause of dementia. Its increased prevalence in developed countries, due to the sharp rise in ageing populations, presents one of the costliest challenges to modern medicine. In order to find disease-modifying therapies to confront this challenge, a more complete understanding of the pathogenesis of Alzheimer's disease is necessary. Recent studies have revealed increasing evidence for the roles played by microglia, the resident innate immune system cells of the brain. Reflecting the well-established roles of microglia in reacting to pathogens and inflammatory stimuli, there is now a growing literature describing both protective and detrimental effects for individual cytokines and chemokines produced by microglia in Alzheimer's disease. A smaller but increasing number of studies have also addressed the divergent roles played by microglial neurotrophic and neurogenic factors, and how their perturbation may play a key role in the pathogenesis of Alzheimer's disease. Here we review recent findings on the roles played by microglia in neuroinflammation, neuronal survival and neurogenesis in Alzheimer's disease. In each case, landmark studies have provided evidence for the divergent ways in which microglia can either promote neuronal function and survival, or perturb neuronal function, leading to cell death. In many cases, the secreted molecules of microglia can lead to divergent effects depending on the magnitude and context of microglial activation. This suggests that microglial functions must be maintained in a fine equilibrium, in order to support healthy neuronal function, and that the cellular microenvironment in the Alzheimer's disease brain disrupts this fine balance, leading to neurodegeneration. Thus, an understanding of microglial homeostasis, both in health and across the trajectory of the disease state, will improve our understanding of the pathogenic mechanisms underlying Alzheimer's disease, and will hopefully lead to the development of microglial-based therapeutic strategies to restore equilibrium in the Alzheimer's disease brain.

CD200 is overexpressed in neuroblastoma and regulates tumor immune microenvironment

Patients with pediatric cancers such as neuroblastoma (NB) are often unresponsive to checkpoint blockade immunotherapy. One major factor in pediatric tumor resistance to immunotherapy is considered to be the low mutation rate of pediatric tumors. Another factor may be the overexpression of additional inhibitory pathways. While analyzing the RNA-sequencing database TARGET, we found that human NB tumors overexpress immune checkpoint molecule CD200. To determine its significance and impact on tumor immune microenvironment, we analyzed 49 cases of previously untreated, surgically removed NB tumors using immunohistochemistry and multi-color flow cytometry (FACS). We found that CD200 is overexpressed in more than 90% of NB tumors. In the tumor microenvironment of NB, CD200 is mainly overexpressed in CD45^- NB tumor cells, while its cognate receptor (CD200R) is mainly expressed in HLA-DR⁺CD14⁺ myeloid cells and CD11c⁺ dendritic cells. Low-level expression of CD200R is also observed in tumor-infiltrating CD4⁺ and CD8⁺ T cells. In NB tumors with higher CD200 expression (CD200^high), we observed lower numbers of HLA-DR⁺CD14⁺ myeloid cells and less tumor-infiltrating CD4⁺ and CD8⁺ T cells. Moreover, we found that CD4⁺ and CD8⁺ T cells produced less IFN-γ and/or TNF-α in CD200^high NB tumors. Thus, CD200-CD200R pathway appears to downregulate anti-tumor immunity in the tumor microenvironment of NB tumors, and blockade of this pathway may be beneficial for NB patients.

Diminution of Phagocytosed Micro/Nanoparticles by Tethering with Immunoregulatory CD200 Protein

CD200 is known as an anti-inflammatory transmembrane glycoprotein in the immunoglobulin superfamily. CD200 interacts with its receptor CD200R which is highly expressed on myeloid cells such as macrophages and neutrophils. CD200-CD200R interaction has known to reduce macrophage activation and chronic inflammation. To harness the immunomodulatory property of CD200 for surface modification, CD200-streptavidin fusion protein was expressed from bacteria transformed with pET20b plasmid encoded with CD200 extracellular domain and core streptavidin. The purified CD200-SA protein was bound to biotin-coated fluorescent polystyrene particles of various sizes ranging from 0.15 to 2 µm. THP-1 macrophages were cultivated with CD200-modified micro/nanoparticles in comparison with controls. Our results showed that both nano- and micro-sized particles decorated with CD200 decreased phagocytosis activities of THP-1 macrophages. Such diminution of phagocytosis was examined to be associated with downregulation of Toll-like receptor 4 (TLR4) expression on the surface of macrophages. Moreover, THP-1 macrophages treated with CD200-coated particles decreased the secretion of tumor necrosis factor-α (TNF-α).