m6A mRNA methylation-directed myeloid cell activation controls progression of NAFLD and obesity

BackgroundTherapeutically targeting tumor myeloid cells has emerged as a novel and complementary strategy to existing cancer immunotherapy approaches. The interaction of tumor expressed CD47 with SIRP alpha (signal regulatory protein-alphaa, SIRPA) on macrophages, dendritic cells and neutrophils inhibits key immune effector mechanisms. Targeting SIRPa-CD47 represents a novel approach to enhance anti-tumor immunity by augmenting or reactivating critical tumor clearance mechanisms.H5F9, an antibody against CD47, has shown promising therapeutic activities in patients with MSD, AML and NHL. However, agents targeting CD47 present hematological toxicities and present a huge antigen sink leading to not achieving an optimum therapeutic window. Our approach is to target SIRP alpha, the receptor of CD47 and focus therapeutic targeting to relevant mechanisms related to phagocytosis and myeloid cell activation and at the same time avoid undesired effects of blocking CD47. SIRP gamma, a very close relative of SIRP alpha is expressed on T cells and also binds to CD47. It has been shown that blockade of SIRP gamma-CD47 interaction inhibits T cell proliferation and blocks trans-endothelial T cell migration. Hence, our aim is to generate SIRP alpha selective antibodies that do not cross-react with SIRP gamma and have minimal impact on T cell functions.MethodsUsing Apexigen’s APXiMAB™ proprietary antibody discovery platform, we have generated two novel anti-SIRP alpha antibodies (APX701 & APX702) with differentiated properties as compared to other approaches targeting the CD47/SIRP alpha axis. We have used ELISA, FACS based cell binding and blocking assays, and functional assays including in vitro phagocytosis and antibody-dependent cell phagocytosis (ADCP) in combination with tumor-opsonizing antibody to select APX701 & APX702.ResultsOur novel preclinical-stage APX701 & APX702 antibodies have demonstrated the following attributes: high binding affinity to human SIRP alpha (APX701 Kd = 0.95nM, APX702 Kd = 0.88nM), no binding to SIRP gamma, efficient blockade of SIRP alpha binding to CD47(APX701 IC50 = 1.04nM, APX702 IC50 = 0.80nM), potent macrophage mediated phagocytosis, enhancement of ADCP mediated by tumor-opsonizing antibody and favorable developability CMC profiles. In comparison with the benchmark antibody OSE-172, APX701 & APX702 showed potent phagocytosis activity and ADCP enhancement in all donors tested while OSE-172 induced phagocytosis in only 50% of the donors. This may result from the fact that APX701 and APX702 bind to all major SIRP alpha variants (V1, V2 & V8; covering ~92% population) while OSE 172 only binds to SIRPalpha V1 (~50% population).ConclusionsAPX701 and APX702 demonstrate differentiated anti-SIRPalpha activities by enhancing myeloid cell-mediated anti-tumor immunity and reactivating critical tumor clearance mechanisms within the tumor microenvironment.

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Adjuvant pretreatment with alum protects neonatal mice in sepsis through myeloid cell activation

Clinical & Experimental Immunology ◽

10.1111/cei.13072 ◽

2017 ◽

Vol 191 (3) ◽

pp. 268-278 ◽

Cited By ~ 3

Author(s):

J. C. Rincon ◽

A. L. Cuenca ◽

S. L. Raymond ◽

B. Mathias ◽

D. C. Nacionales ◽

...

Keyword(s):

Cell Activation ◽

Myeloid Cell ◽

Neonatal Mice

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Triggering receptor expressed on myeloid cells-2 expression in the brain is required for maximal phagocytic activity and improved neurological outcomes following experimental stroke

Journal of Cerebral Blood Flow & Metabolism ◽

10.1177/0271678x18817282 ◽

2018 ◽

Vol 39 (10) ◽

pp. 1906-1918 ◽

Cited By ~ 14

Author(s):

Kota Kurisu ◽

Zhen Zheng ◽

Jong Youl Kim ◽

Jian Shi ◽

Atsushi Kanoke ◽

...

Keyword(s):

Cell Activation ◽

Infarct Volume ◽

Myeloid Cells ◽

Myeloid Cell ◽

Cerebrovascular Diseases ◽

Stroke Recovery ◽

Experimental Stroke ◽

Neurological Outcomes ◽

Intact Brain ◽

The Brain

Triggering receptor expressed on myeloid cells-2 (TREM2) is an innate immune receptor that promotes phagocytosis by myeloid cells such as microglia and macrophages. We previously showed that TREM2 deficiency worsened outcomes from experimental stroke and impeded phagocytosis. However, myeloid cells participating in stroke pathology include both brain resident microglia and circulating macrophages. We now clarify whether TREM2 on brain microglia or circulating macrophages contribute to its beneficial role in ischemic stroke by generating bone marrow (BM) chimeric mice. BM chimera mice from TREM2 knockout (KO) or wild type (Wt) mice were used as donor and recipient mice. Mice were subjected to experimental stroke, and neurological function and infarct volume were assessed. Mice with intact TREM2 in brain microglia showed better neurological recovery and reduced infarct volumes, compared with mice lacking microglial TREM2. Myeloid cell activation and numbers of phagocytes were decreased in mice lacking brain TREM2, compared with mice with intact brain TREM2. These results suggest that TREM2 expression is important for post-stroke recovery, and that TREM2 expression on brain resident microglia is more essential to this recovery, than that of circulating macrophages. These findings might suggest a new therapeutic target for cerebrovascular diseases.

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Murine myeloid cell MCPIP1 suppresses autoimmunity by regulating B-cell expansion and differentiation

Disease Models & Mechanisms ◽

10.1242/dmm.047589 ◽

2021 ◽

Vol 14 (3) ◽

pp. dmm047589

Author(s):

Ewelina Dobosz ◽

Georg Lorenz ◽

Andrea Ribeiro ◽

Vivian Würf ◽

Marta Wadowska ◽

...

Keyword(s):

Autoimmune Disease ◽

Immune Responses ◽

Cell Activation ◽

Plasma Cells ◽

Myeloid Cell ◽

Skin Inflammation ◽

Adaptive Immune ◽

Systemic Autoimmunity ◽

Key Factor ◽

Old Mice

ABSTRACTMyeloid-derived cells, in particular macrophages, are increasingly recognized as critical regulators of the balance of immunity and tolerance. However, whether they initiate autoimmune disease or perpetuate disease progression in terms of epiphenomena remains undefined.Here, we show that depletion of MCPIP1 in macrophages and granulocytes (Mcpip1fl/fl-LysMcre+ C57BL/6 mice) is sufficient to trigger severe autoimmune disease. This was evidenced by the expansion of B cells and plasma cells and spontaneous production of autoantibodies, including anti-dsDNA, anti-Smith and anti-histone antibodies. Consequently, we document evidence of severe skin inflammation, pneumonitis and histopathologic evidence of glomerular IgG deposits alongside mesangioproliferative nephritis in 6-month-old mice. These phenomena are related to systemic autoinflammation, which secondarily induces a set of cytokines such as Baff, Il5, Il9 and Cd40L, affecting adaptive immune responses. Therefore, abnormal macrophage activation is a key factor involved in the loss of immune tolerance.Overall, we demonstrate that deficiency of MCPIP1 solely in myeloid cells triggers systemic lupus-like autoimmunity and that the control of myeloid cell activation is a crucial checkpoint in the development of systemic autoimmunity.

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IMMU-04. UNVEILING THE TUMOR-METABOLOME-IMMUNITY AXIS OF GLIOMA

Neuro-Oncology ◽

10.1093/neuonc/noab196.364 ◽

2021 ◽

Vol 23 (Supplement_6) ◽

pp. vi92-vi92

Author(s):

Mirco Friedrich ◽

Lukas Bunse ◽

Roman Sankowski ◽

Wolfgang Wick ◽

Marco Prinz ◽

...

Keyword(s):

T Cell ◽

Single Cell ◽

T Cell Activation ◽

Cell Activation ◽

Immune Cell ◽

Myeloid Cell ◽

Tumor Evolution ◽

Large Neutral Amino Acid ◽

Immune Microenvironment ◽

Idh Mutations

Abstract The glioma microenvironment orchestrates tumor evolution, progression, and resistance to therapy. In high-grade gliomas, microglia and monocyte-derived macrophages constitute up to 70% of the tumor mass. However, the dynamics and phenotypes of intratumoral myeloid cells during tumor progression are poorly understood. Here we define myeloid cellular states in gliomas by longitudinal single-cell profiling and demonstrate their strict control by the tumor genotype. We report the unexpected and clinically highly relevant finding that human as well as murine gliomas with Isocitrate Dehydrogenase (IDH)1-R132H, a key oncogenic driver mutation of glioma, subdue their innate immune microenvironment by prompting a multifaceted reprogramming of myeloid and T cell metabolism. We employed integrated single-cell transcriptomic, time-of-flight mass cytometry and proteomic analyses of human healthy cortex control and glioma samples to identify myeloid cell subsets with distinct fates in IDH-mutated glioma that diverge from canonical trajectories of antigen-presenting cells as a result of a monocyte-to-macrophage differentiation block. Moving beyond single time point assessments, we now longitudinally describe differential immune cell infiltration and phenotype dynamics during glioma progression that are orchestrated by a fluctuating network of resident microglial cells and educated recruited immune cells. IDH mutations in glioma induce a tolerogenic alignment of their immune microenvironment through increased tryptophan uptake via large neutral amino acid transporter (LAT1)-CD98 and subsequent activation of the aryl hydrocarbon receptor (AHR) in educated blood-borne macrophages. In experimental tumor models, this immunosuppressive phenotype was reverted by LAT1-CD98 and AHR inhibitors. Taken together with direct effects on T cell activation, our findings not only link this oncogenic metabolic pathway to distinct immunosuppressive pathways but also provide the rationale and novel molecular targets for the development of immunotherapeutic concepts addressing the disease-defining microenvironmental effects of IDH mutations.

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Membrane-associated and secreted forms of the Rhesus macaque rhadinovirus-encoded CD200 homologue and cellular CD200 demonstrate differential effects on Rhesus Macaque CD200 Receptor signaling and regulation of myeloid cell activation

Journal of Virology ◽

10.1128/jvi.01654-20 ◽

2020 ◽

pp. JVI.01654-20

Author(s):

Ryan D. Estep ◽

Aparna N. Govindan ◽

Kristin Fitzpatrick ◽

Tiffany C. Blair ◽

S.A. Rahim Rezaee ◽

...

Keyword(s):

Immune Responses ◽

Rhesus Macaque ◽

Cell Activation ◽

Myeloid Cell ◽

Functional Protein ◽

Dna Viruses ◽

Cd200 Receptor ◽

First Time

The CD200-CD200R pathway is involved in inhibition of immune responses, and the importance of this pathway to infectious disease is highlighted by the fact that viral CD200 (vCD200) molecules have been found to be encoded by several DNA viruses, including the human gammaherpesvirus Kaposi’s sarcoma-associated herpesvirus (KSHV), and the closely related rhesus macaque rhadinovirus (RRV). KSHV vCD200 is the most extensively studied vCD200 molecule, however, the only herpesvirus vCD200 molecule to be examined in vivo is that encoded by RRV. Our prior studies have demonstrated that RRV vCD200 is a functional CD200 homologue that is capable of affecting immune responses in vivo, and further, that RRV can express a secreted form of vCD200 (vCD200-Sec) during infection. Despite this information, RRV vCD200 has not been examined specifically for effects on RM CD200R signaling, and the functionality of vCD200-Sec has not been examined in any context. Thus, we developed an in vitro model system in which B cells expressing vCD200 were utilized to assess the effects of this molecule on the regulation of myeloid cells expressing RM CD200R, mimicking interactions that are predicted to occur in vivo. Our findings suggest that RRV vCD200 can bind and induce functional signals through RM CD200R, while vCD200-Sec represents a non-functional protein incapable of affecting CD200R signaling. We also provide the first demonstration of the function of RM CD200, which appears to possess more robust signaling capabilities than RRV vCD200, and also show that KSHV vCD200 does not efficiently induce signaling via RM CD200R.IMPORTANCE Viral CD200 homologues are encoded by KSHV and the closely related RRV. Though RRV vCD200 has been examined, questions still exist in regard to the ability of this molecule to induce signaling via rhesus macaque CD200R, as well as the potential function of a secreted form of vCD200. Further, all previous in vitro studies of RRV vCD200 have utilized an Fc fusion protein to examine functionality, which does not replicate the structural properties of the membrane-associated form of vCD200 that is naturally produced during RRV infection. In this study, we demonstrate for the first time that membrane-expressed RRV vCD200 is capable of inducing signal transduction via RM CD200R, while the secreted form of vCD200 appears to be non-functional. Further, we also demonstrate that RM CD200 induces signaling via RM CD200R, and is more robust than RRV vCD200, while KSHV vCD200 does not appear to induce efficient signaling via RM CD200R.

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Effects of L-arginine infusion during ischemia on gut blood perfusion, oxygen tension, and circulating myeloid cell activation in a murine gut ischemia/reperfusion model

Journal of Parenteral and Enteral Nutrition ◽

10.1177/0148607104028004224 ◽

2004 ◽

Vol 28 (4) ◽

pp. 224-230 ◽

Cited By ~ 24

Author(s):

K Fukatsu ◽

C Ueno ◽

Y Maeshima ◽

E Hara ◽

H Nagayoshi ◽

...

Keyword(s):

Oxygen Tension ◽

Cell Activation ◽

Ischemia Reperfusion ◽

Myeloid Cell ◽

Blood Perfusion ◽

Arginine Infusion

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B-cells are abnormal in psychosocial stress and regulate meningeal myeloid cell activation

Brain Behavior and Immunity ◽

10.1016/j.bbi.2021.08.002 ◽

2021 ◽

Author(s):

Mary-Ellen Lynall ◽

Stacey L. Kigar ◽

Michael L. Lehmann ◽

Allison E. DePuyt ◽

Zewen Kelvin Tuong ◽

...

Keyword(s):

B Cells ◽

Psychosocial Stress ◽

Cell Activation ◽

Myeloid Cell

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Coevolution of TH1, TH2, and TH17 Responses during Repeated Pulmonary Exposure toAspergillus fumigatusConidia

Infection and Immunity ◽

10.1128/iai.00508-10 ◽

2010 ◽

Vol 79 (1) ◽

pp. 125-135 ◽

Cited By ~ 59

Author(s):

Benjamin J. Murdock ◽

Andrew B. Shreiner ◽

Roderick A. McDonald ◽

John J. Osterholzer ◽

Eric S. White ◽

...

Keyword(s):

T Cell ◽

T Cell Activation ◽

Cell Activation ◽

Allergic Bronchopulmonary Aspergillosis ◽

Myeloid Cell ◽

Hyphal Growth ◽

Cell Polarization ◽

Repeated Exposure ◽

Invasive Infection ◽

Pulmonary Exposure

ABSTRACTAspergillus fumigatus, a ubiquitous airborne fungus, can cause invasive infection in immunocompromised individuals but also triggers allergic bronchopulmonary aspergillosis in a subset of otherwise healthy individuals repeatedly exposed to the organism. This study addresses a critical gap in our understanding of the immunoregulation in response to repeated exposure toA. fumigatusconidia. C57BL/6 mice were challenged intranasally withA. fumigatusconidia weekly, and leukocyte composition, activation, and cytokine production were examined after two, four, and eight challenges. Approximately 99% ofA. fumigatusconidia were cleared within 24 h after inoculation, and repeated exposure toA. fumigatusconidia did not result in hyphal growth or accumulation of conidia with time. After 2 challenges, there was an early influx of neutrophils and regulatory T (Treg) cells into the lungs but minimal inflammation. Repeated exposure promoted sustained expansion of the draining lymph nodes, while the influx of eosinophils and other myeloid cells into the lungs peaked after four exposures and then decreased despite continuedA. fumigatuschallenges. Goblet cell metaplasia and low-level fibrosis were evident during the response. Repeated exposure toA. fumigatusconidia induced T cell activation in the lungs and the codevelopment by four exposures of TH1, TH2, and TH17 responses in the lungs, which were maintained through eight exposures. Changes in CD4 T cell polarization or Tregnumbers did not account for the reduction in myeloid cell numbers later in the response, suggesting a non-T-cell regulatory pathway involved in dampening inflammation during repeated exposure toA. fumigatusconidia.

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Tissue plasminogen activator worsens experimental autoimmune encephalomyelitis by complementary actions on lymphoid and myeloid cell responses

10.21203/rs.3.rs-34631/v1 ◽

2020 ◽

Author(s):

Pauline Hélie ◽

Celia Camacho Toledano ◽

Antonio J Miralles ◽

Maria Cristina Ortega ◽

Virginia Vila del Sol ◽

...

Keyword(s):

Multiple Sclerosis ◽

Experimental Autoimmune Encephalomyelitis ◽

Plasminogen Activator ◽

Tissue Plasminogen Activator ◽

T Cell Activation ◽

Cell Activation ◽

Myeloid Cell ◽

Autoimmune Encephalomyelitis ◽

Tissue Plasminogen ◽

Experimental Autoimmune

Abstract Background Tissue plasminogen activator (tPA) is a serine protease involved in fibrinolysis. It is released by endothelial cells, but also expressed by neurons and glial cells in the central nervous system (CNS). Interestingly, this enzyme also contributes to pathological processes in the CNS such as neuroinflammation by activating microglia and increasing blood-brain-barrier permeability. Nevertheless, its role in the control of adaptive and innate immune response remains poorly understood. Methods tPA effects on myeloid and lymphoid cell response were studied in vivo in the mouse model of multiple sclerosis experimental autoimmune encephalomyelitis and in vitro in splenocytes. Results tPA−/− animals exhibited less severe experimental autoimmune encephalomyelitis than their wild type counterparts. This was accompanied by a reduction in both lymphoid and myeloid cell populations in the spinal cord parenchyma. In parallel, tPA increased T cell activation and proliferation, as well as cytokine production by a protease-dependent mechanism and via plasmin generation. In addition, tPA raised the expression of MHC-II and the co-stimulatory molecule CD80 and CD86 at the surface of dendritic cells and macrophages by an effect dependent of the proteolytic activity of tPA and of the activation of epidermal growth factor receptor. Conclusions Our study provides new insights into the mechanisms responsible for the harmful functions of tPA in multiple sclerosis and its animal models: tPA promotes the proliferation and activation of both lymphoid and myeloid populations by distinct, though complementary, mechanisms.

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