InVivoMAb anti-mouse/human CD11b

Catalog #BE0007
Product Citations:
21
Clone:
M1/70
Reactivities:
Mouse, Human

$164.00 - $4,280.00

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Product Details

The M1/70 monoclonal antibody reacts with mouse and human CD11b, a 170 kDa membrane glycoprotein also known as integrin alpha M (ITGAM). CD11b belongs to the integrin alpha family and is primarily expressed on granulocytes and monocytes/macrophages but also expressed on dendritic cells, NK cells, and subsets of T and B cells. CD11b and CD18 combine to form Mac-1. Mac-1 functions as a complement receptor as well as a receptor for fibrinogen, factor X, and ICAM1.

Specifications

Isotype Rat IgG2b, κ
Recommended Isotype Control(s) InVivoMAb rat IgG2b isotype control, anti-keyhole limpet hemocyanin
Recommended Dilution Buffer InVivoPure pH 7.0 Dilution Buffer
Conjugation This product is unconjugated. Conjugation is available via our Antibody Conjugation Services.
Immunogen B10 mouse spleen cells enriched for T cells
Reported Applications in vivo CD11b neutralization
ILC2 cell purification
Flow cytometry
Formulation PBS, pH 7.0
Contains no stabilizers or preservatives
Endotoxin <2EU/mg (<0.002EU/μg)
Determined by LAL gel clotting assay
Purity >95%
Determined by SDS-PAGE
Sterility 0.2 µm filtration
Production Purified from cell culture supernatant in an animal-free facility
Purification Protein G
RRID AB_1107582
Molecular Weight 150 kDa
Storage The antibody solution should be stored at the stock concentration at 4°C. Do not freeze.
Flow Cytometry
Becker, A. M., et al. (2015). "ADAM17 limits the expression of CSF1R on murine hematopoietic progenitors" Exp Hematol 43(1): 44-52 e41-43. PubMed

All-lymphoid progenitors (ALPs) yield few myeloid cells in vivo, but readily generate such cells in vitro. The basis for this difference remains unknown. We hypothesized that ALPs limit responsiveness to in vivo concentrations of myeloid-promoting cytokines by reducing expression of the corresponding receptors, potentially through posttranscriptional mechanisms. Consistent with such a mechanism, ALPs express higher levels of CSF1R transcripts than their upstream precursors, yet show limited cell-surface protein expression of colony-stimulating factor 1 receptor (CSF1R). All-lymphoid progenitors and other hematopoietic progenitors deficient in A disintegrin and metalloproteinase domain 17 (ADAM17), display elevated cell surface CSF1R expression. ADAM17(-/-) ALPs, however, fail to yield myeloid cells upon transplantation into irradiated recipients. Moreover, ADAM17(-/-) ALPs yield fewer macrophages in vitro than control ALPs at high concentrations of macrophage colony stimulating factor. Mice with hematopoietic-specific deletion of ADAM17 have normal numbers of myeloid and lymphoid progenitors and mature cells in vivo. These data demonstrate that ADAM17 limits CSF1R protein expression on hematopoietic progenitors, but that compensatory mechanisms prevent elevated CSF1R levels from altering lymphoid progenitor potential.

ILC2 cell purification
Liu, B., et al. (2015). "Collaborative interactions between type 2 innate lymphoid cells and antigen-specific CD4+ Th2 cells exacerbate murine allergic airway diseases with prominent eosinophilia" J Immunol 194(8): 3583-3593. PubMed

Type-2 innate lymphoid cells (ILC2s) and the acquired CD4(+) Th2 and Th17 cells contribute to the pathogenesis of experimental asthma; however, their roles in Ag-driven exacerbation of chronic murine allergic airway diseases remain elusive. In this study, we report that repeated intranasal rechallenges with only OVA Ag were sufficient to trigger airway hyperresponsiveness, prominent eosinophilic inflammation, and significantly increased serum OVA-specific IgG1 and IgE in rested mice that previously developed murine allergic airway diseases. The recall response to repeated OVA inoculation preferentially triggered a further increase of lung OVA-specific CD4(+) Th2 cells, whereas CD4(+) Th17 and ILC2 cell numbers remained constant. Furthermore, the acquired CD4(+) Th17 cells in Stat6(-/-)/IL-17-GFP mice, or innate ILC2s in CD4(+) T cell-ablated mice, failed to mount an allergic recall response to OVA Ag. After repeated OVA rechallenge or CD4(+) T cell ablation, the increase or loss of CD4(+) Th2 cells resulted in an enhanced or reduced IL-13 production by lung ILC2s in response to IL-25 and IL-33 stimulation, respectively. In return, ILC2s enhanced Ag-mediated proliferation of cocultured CD4(+) Th2 cells and their cytokine production, and promoted eosinophilic airway inflammation and goblet cell hyperplasia driven by adoptively transferred Ag-specific CD4(+) Th2 cells. Thus, these results suggest that an allergic recall response to recurring Ag exposures preferentially triggers an increase of Ag-specific CD4(+) Th2 cells, which facilitates the collaborative interactions between acquired CD4(+) Th2 cells and innate ILC2s to drive the exacerbation of a murine allergic airway diseases with an eosinophilic phenotype.

in vivo CD11b neutralization
Yokota, N., et al. (2014). "Contributions of thrombin targets to tissue factor-dependent metastasis in hyperthrombotic mice" J Thromb Haemost 12(1): 71-81. PubMed

BACKGROUND: Tumor cell tissue factor (TF)-initiated coagulation supports hematogenous metastasis by fibrin formation, platelet activation and monocyte/macrophage recruitment. Recent studies identified host anticoagulant mechanisms as a major impediment to successful hematogenous tumor cell metastasis. OBJECTIVE: Here we address mechanisms that contribute to enhanced metastasis in hyperthrombotic mice with functional thrombomodulin deficiency (TM(Pro) mice). METHODS: Pharmacological and genetic approaches were combined to characterize relevant thrombin targets in a mouse model of experimental hematogenous metastasis. RESULTS: TF-dependent, but contact pathway-independent, syngeneic breast cancer metastasis was associated with marked platelet hyperreactivity and formation of leukocyte-platelet aggregates in immune-competent TM(Pro) mice. Blockade of CD11b or genetic deletion of platelet glycoprotein Ibalpha excluded contributions of these receptors to enhanced platelet-dependent metastasis in hyperthrombotic mice. Mice with very low levels of the endothelial protein C receptor (EPCR) did not phenocopy the enhanced metastasis seen in TM(Pro) mice. Genetic deletion of the thrombin receptor PAR1 or endothelial thrombin signaling targets alone did not diminish enhanced metastasis in TM(Pro) mice. Combined deficiency of PAR1 on tumor cells and the host reduced metastasis in TM(Pro) mice. CONCLUSIONS: Metastasis in the hyperthrombotic TM(Pro) mouse model is mediated by platelet hyperreactivity and contributions of PAR1 signaling on tumor and host cells.

in vivo CD11b neutralization
Li, W., et al. (2012). "Intravital 2-photon imaging of leukocyte trafficking in beating heart" J Clin Invest 122(7): 2499-2508. PubMed

Two-photon intravital microscopy has substantially broadened our understanding of tissue- and organ-specific differences in the regulation of inflammatory responses. However, little is known about the dynamic regulation of leukocyte recruitment into inflamed heart tissue, largely due to technical difficulties inherent in imaging moving tissue. Here, we report a method for imaging beating murine hearts using intravital 2-photon microscopy. Using this method, we visualized neutrophil trafficking at baseline and during inflammation. Ischemia reperfusion injury induced by transplantation or transient coronary artery ligation led to recruitment of neutrophils to the heart, their extravasation from coronary veins, and infiltration of the myocardium where they formed large clusters. Grafting hearts containing mutant ICAM-1, a ligand important for neutrophil recruitment, reduced the crawling velocities of neutrophils within vessels, and markedly inhibited their extravasation. Similar impairment was seen with the inhibition of Mac-1, a receptor for ICAM-1. Blockade of LFA-1, another ICAM-1 receptor, prevented neutrophil adherence to endothelium and extravasation in heart grafts. As inflammatory responses in the heart are of great relevance to public health, this imaging approach holds promise for studying cardiac-specific mechanisms of leukocyte recruitment and identifying novel therapeutic targets for treating heart disease.

in vivo CD11b neutralization
Ahn, G. O., et al. (2010). "Inhibition of Mac-1 (CD11b/CD18) enhances tumor response to radiation by reducing myeloid cell recruitment" Proc Natl Acad Sci U S A 107(18): 8363-8368. PubMed

Despite recent advances in radiotherapy, loco-regional failures are still the leading cause of death in many cancer patients. We have previously reported that bone marrow-derived CD11b(+) myeloid cells are recruited to tumors grown in irradiated tissues, thereby restoring the vasculature and tumor growth. In this study, we examined whether neutralizing CD11b monoclonal antibodies could inhibit the recruitment of myeloid cells into irradiated tumors and inhibit their regrowth. We observed a significant enhancement of antitumor response to radiation in squamous cell carcinoma xenografts in mice when CD11b antibodies are administered systemically. Histological examination of tumors revealed that CD11b antibodies reduced infiltration of myeloid cells expressing S100A8 and matrix metalloproteinase-9. CD11b antibodies further inhibited bone marrow-derived cell adhesion and transmigration to C166 endothelial cell monolayers and chemotactic stimuli, respectively, to levels comparable to those from CD11b knockout or CD18 hypomorphic mice. Given the clinical availability of humanized CD18 antibodies, we tested two murine tumor models in CD18 hypomorphic or CD11b knockout mice and found that tumors were more sensitive to irradiation when grown in CD18 hypomorphic mice but not in CD11b knockout mice. When CD18 hypomorphism was partially rescued by reconstitution with the wild-type bone marrow, the resistance of the tumors to irradiation was restored. Our study thus supports the rationale of using clinically available Mac-1 (CD11b/CD18) antibodies as an adjuvant therapy to radiotherapy.

    • In Vivo
    • ,
    • Mus musculus (House mouse)
    • ,
    • Cancer Research
    • ,
    • Immunology and Microbiology
    BCL2 Inhibition Reveals a Dendritic Cell-Specific Immune Checkpoint That Controls Tumor Immunosurveillance.

    In Cancer Discovery on 1 November 2023 by Zhao, L., Liu, P., et al.

    PubMed

    We developed a phenotypic screening platform for the functional exploration of dendritic cells (DC). Here, we report a genome-wide CRISPR screen that revealed BCL2 as an endogenous inhibitor of DC function. Knockout of BCL2 enhanced DC antigen presentation and activation as well as the capacity of DCs to control tumors and to synergize with PD-1 blockade. The pharmacologic BCL2 inhibitors venetoclax and navitoclax phenocopied these effects and caused a cDC1-dependent regression of orthotopic lung cancers and fibrosarcomas. Thus, solid tumors failed to respond to BCL2 inhibition in mice constitutively devoid of cDC1, and this was reversed by the infusion of DCs. Moreover, cDC1 depletion reduced the therapeutic efficacy of BCL2 inhibitors alone or in combination with PD-1 blockade and treatment with venetoclax caused cDC1 activation, both in mice and in patients. In conclusion, genetic and pharmacologic BCL2 inhibition unveils a DC-specific immune checkpoint that restrains tumor immunosurveillance. BCL2 inhibition improves the capacity of DCs to stimulate anticancer immunity and restrain cancer growth in an immunocompetent context but not in mice lacking cDC1 or mature T cells. This study indicates that BCL2 blockade can be used to sensitize solid cancers to PD-1/PD-L1-targeting immunotherapy. This article is featured in Selected Articles from This Issue, p. 2293. ©2023 American Association for Cancer Research.

    • Mus musculus (House mouse)
    CCR4 and CCR7 differentially regulate thymocyte localization with distinct outcomes for central tolerance.

    In eLife on 2 June 2023 by Li, Y., Guaman Tipan, P., et al.

    PubMed

    Central tolerance ensures autoreactive T cells are eliminated or diverted to the regulatory T cell lineage, thus preventing autoimmunity. To undergo central tolerance, thymocytes must enter the medulla to test their T-cell receptors (TCRs) for autoreactivity against the diverse self-antigens displayed by antigen-presenting cells (APCs). While CCR7 is known to promote thymocyte medullary entry and negative selection, our previous studies implicate CCR4 in these processes, raising the question of whether CCR4 and CCR7 play distinct or redundant roles in central tolerance. Here, synchronized positive selection assays, two-photon time-lapse microscopy, and quantification of TCR-signaled apoptotic thymocytes, demonstrate that CCR4 and CCR7 promote medullary accumulation and central tolerance of distinct post-positive selection thymocyte subsets in mice. CCR4 is upregulated within hours of positive selection signaling and promotes medullary entry and clonal deletion of immature post-positive selection thymocytes. In contrast, CCR7 is expressed several days later and is required for medullary localization and negative selection of mature thymocytes. In addition, CCR4 and CCR7 differentially enforce self-tolerance, with CCR4 enforcing tolerance to self-antigens presented by activated APCs, which express CCR4 ligands. Our findings show that CCR7 expression is not synonymous with medullary localization and support a revised model of central tolerance in which CCR4 and CCR7 promote early and late stages of negative selection, respectively, via interactions with distinct APC subsets. © 2023, Li, Guaman Tipan et al.

    • Cancer Research
    • ,
    • Immunology and Microbiology
    Cellular Senescence Is Immunogenic and Promotes Antitumor Immunity.

    In Cancer Discovery on 6 February 2023 by Marin, I., Boix, O., et al.

    PubMed

    Cellular senescence is a stress response that activates innate immune cells, but little is known about its interplay with the adaptive immune system. Here, we show that senescent cells combine several features that render them highly efficient in activating dendritic cells (DC) and antigen-specific CD8 T cells. This includes the release of alarmins, activation of IFN signaling, enhanced MHC class I machinery, and presentation of senescence-associated self-peptides that can activate CD8 T cells. In the context of cancer, immunization with senescent cancer cells elicits strong antitumor protection mediated by DCs and CD8 T cells. Interestingly, this protection is superior to immunization with cancer cells undergoing immunogenic cell death. Finally, the induction of senescence in human primary cancer cells also augments their ability to activate autologous antigen-specific tumor-infiltrating CD8 lymphocytes. Our study indicates that senescent cancer cells can be exploited to develop efficient and protective CD8-dependent antitumor immune responses. Our study shows that senescent cells are endowed with a high immunogenic potential-superior to the gold standard of immunogenic cell death. We harness these properties of senescent cells to trigger efficient and protective CD8-dependent antitumor immune responses. See related article by Chen et al., p. 432. This article is highlighted in the In This Issue feature, p. 247. ©2022 The Authors; Published by the American Association for Cancer Research.

    • Cancer Research
    • ,
    • Cell Biology
    S100A9 Derived from Chemoembolization-Induced Hypoxia Governs Mitochondrial Function in Hepatocellular Carcinoma Progression.

    In Advanced Science (Weinheim, Baden-Wurttemberg, Germany) on 1 October 2022 by Zhong, C., Niu, Y., et al.

    PubMed

    Transarterial chemoembolization (TACE) is the major treatment for advanced hepatocellular carcinoma (HCC), but it may cause hypoxic environment, leading to rapid progression after treatment. Here, using high-throughput sequencing on different models, S100 calcium binding protein A9 (S100A9) is identified as a key oncogene involved in post-TACE progression. Depletion or pharmacologic inhibition of S100A9 significantly dampens the growth and metastatic ability of HCC. Mechanistically, TACE induces S100A9 via hypoxia-inducible factor 1α (HIF1A)-mediated pathway. S100A9 acts as a scaffold recruiting ubiquitin specific peptidase 10 and phosphoglycerate mutase family member 5 (PGAM5) to form a tripolymer, causing the deubiquitination and stabilization of PGAM5, leading to mitochondrial fission and reactive oxygen species production, thereby promoting the growth and metastasis of HCC. Higher S100A9 level in HCC tissue or in serum predicts a worse outcome for HCC patients. Collectively, this study identifies S100A9 as a key driver for post-TACE HCC progression. Targeting S100A9 may be a promising therapeutic strategy for HCC patients. © 2022 The Authors. Advanced Science published by Wiley-VCH GmbH.

    • IHC
    • ,
    • Immunology and Microbiology
    Pro-inflammatory cytokines and leukocyte integrins associated with chronic neuropathic pain in traumatic and inflammatory neuropathies: Initial observations and hypotheses.

    In Frontiers in Immunology on 20 August 2022 by Dong, C. & Ubogu, E. E.

    PubMed

    Leukocyte infiltration and persistence within peripheral nerves have been implicated in chronic nociception pathogenesis in murine peripheral neuropathy models. Endoneurial cytokine and chemokine expression contribute to leukocyte infiltration and maintenance of a pro-inflammatory state that delays peripheral nerve recovery and promotes chronic pain behaviors in these mice. However, there has been a failure to translate murine model data into safe and effective treatments for chronic neuropathic pain in peripheral neuropathy patients, or develop reliable biomarkers that may help diagnose or determine treatment responses in affected patients. Initial work showed that persistent sciatic nerve CD11b+ CD45+ leukocyte infiltration was associated with disease severity in three mouse models of inflammatory and traumatic peripheral neuropathies, implying a direct contributing role in disease pathogenesis. In support of this, CD11b+ leukocytes were also seen in the sural nerve biopsies of chronic neuropathic pain patients with three different peripheral neuropathies. Systemic CD11b antagonism using a validated function-neutralizing monoclonal antibody effectively treated chronic nociception following unilateral sciatic nerve crush injury (a representative traumatic neuropathy model associated with axonal degeneration and increased blood-nerve barrier permeability) and does not cause drug addiction behaviors in adult mice. These data suggest that CD11b could be an effective molecular target for chronic neuropathic pain treatment in inflammatory and traumatic peripheral neuropathies. Despite known murine peripheral neuropathy model limitations, our initial work suggests that early expression of pro-inflammatory cytokines, such as tissue inhibitor of metalloproteinases-1 may predict subsequent chronic nociception development following unilateral sciatic nerve crush injury. Studies aligning animal model investigation with observational data from well-characterized human peripheral neuropathies, including transcriptomics and proteomics, as well as animal model studies using a human clinical trial design should foster the identification of clinically relevant biomarkers and effective targeted treatments with limited addiction potential for chronic neuropathic pain in peripheral neuropathy patients. Copyright © 2022 Dong and Ubogu.

    • Immu-depl
    • ,
    • Neutralization
    • ,
    • Homo sapiens (Human)
    • ,
    • Cancer Research
    • ,
    • Immunology and Microbiology
    Cancer cell-expressed BTNL2 facilitates tumour immune escape via engagement with IL-17A-producing γδ T cells.

    In Nature Communications on 11 January 2022 by Du, Y., Peng, Q., et al.

    PubMed

    Therapeutic blockade of the immune checkpoint proteins programmed cell death protein 1 (PD-1) and cytotoxic T lymphocyte antigen 4 (CTLA4) has transformed cancer treatment. However, the overall response rate to these treatments is low, suggesting that immune checkpoint activation is not the only mechanism leading to dysfunctional anti-tumour immunity. Here we show that butyrophilin-like protein 2 (BTNL2) is a potent suppressor of the anti-tumour immune response. Antibody-mediated blockade of BTNL2 attenuates tumour progression in multiple in vivo murine tumour models, resulting in prolonged survival of tumour-bearing mice. Mechanistically, BTNL2 interacts with local γδ T cell populations to promote IL-17A production in the tumour microenvironment. Inhibition of BTNL2 reduces the number of tumour-infiltrating IL-17A-producing γδ T cells and myeloid-derived suppressor cells, while facilitating cytotoxic CD8+ T cell accumulation. Furthermore, we find high BTNL2 expression in several human tumour samples from highly prevalent cancer types, which negatively correlates with overall patient survival. Thus, our results suggest that BTNL2 is a negative regulator of anti-tumour immunity and a potential target for cancer immunotherapy. © 2022. The Author(s).

    • Cancer Research
    • ,
    • Immunology and Microbiology
    All-trans retinoic acid overcomes solid tumor radioresistance by inducing inflammatory macrophages.

    In Science Immunology on 15 June 2021 by Rao, E., Hou, Y., et al.

    PubMed

    Radiotherapy (RT) is an important anti-cancer treatment modality that activates innate and adaptive immune responses. When all-trans retinoic acid (RA) was administered with radiation, we observed superior antitumor responses compared to ionizing radiation (IR) alone or RA alone. The superior antitumor effects of combination treatment were accompanied by a dramatic increase of TNF-α- and inducible nitric oxide synthase (iNOS)-producing inflammatory macrophages in local and distal non-irradiated (distal) tumors. Inflammatory macrophages are essential for the therapeutic efficacy of combination treatment by inducing effector T cell infiltration and enhancing the effector T cell to regulatory T cell ratio in local and distal tumors. T cells and T cell-derived IFN-γ are crucial for increasing inflammatory macrophage levels in IR and RA treated tumors. Notably, whereas CD8+ T cells are required for the antitumor response to IR, CD4+ T cells are required for the effectiveness of the IR and RA combination. Combination treatment with RA enhanced the abscopal response when radiation and PD-L1 blockade were used together. The synergistic positive feedback loop of inflammatory macrophages and adaptive immunity is required for the antitumor efficacy of IR plus RA combination treatment. Our findings provide a translational and relatively nontoxic strategy for enhancing the local and systemic antitumor effects of IR.

    • FC/FACS
    • ,
    • Mus musculus (House mouse)
    Sequencing-Based Protein Analysis of Single Extracellular Vesicles.

    In ACS Nano on 23 March 2021 by Ko, J., Wang, Y., et al.

    PubMed

    Circulating extracellular vesicles (EVs)-biological nanomaterials shed from most mammalian cells-have emerged as promising biomarkers, drug delivery vesicles, and treatment modulators. While different types of vesicles are being explored for these applications, it is becoming clear that human EVs are quite heterogeneous even in homogeneous or monoclonal cell populations. Since it is the surface EV protein composition that will largely dictate their biological behavior, high-throughput single EV profiling methods are needed to better define EV subpopulations. Here, we present an antibody-based immunosequencing method that allows multiplexed measurement of protein molecules from individual nanometer-sized EVs. We use droplet microfluidics to compartmentalize and barcode individual EVs. The barcodes/antibody-DNA are then sequenced to determine protein composition. Using this highly sensitive technology, we detected specific proteins at the single EV level. We expect that this technology can be further adapted for multiplexed protein analysis of any nanoparticle.

    • FC/FACS
    • ,
    • Mus musculus (House mouse)
    • ,
    • Immunology and Microbiology
    • ,
    • Neuroscience
    Affinity-Restricted Memory B Cells Dominate Recall Responses to Heterologous Flaviviruses.

    In Immunity on 17 November 2020 by Wong, R., Belk, J. A., et al.

    PubMed

    Memory B cells (MBCs) can respond to heterologous antigens either by molding new specificities through secondary germinal centers (GCs) or by selecting preexisting clones without further affinity maturation. To distinguish these mechanisms in flavivirus infections and immunizations, we studied recall responses to envelope protein domain III (DIII). Conditional deletion of activation-induced cytidine deaminase (AID) between heterologous challenges of West Nile, Japanese encephalitis, Zika, and dengue viruses did not affect recall responses. DIII-specific MBCs were contained mostly within the plasma-cell-biased CD80+ subset, and few GCs arose following heterologous boosters, demonstrating that recall responses are confined by preexisting clonal diversity. Measurement of monoclonal antibody (mAb) binding affinity to DIII proteins, timed AID deletion, single-cell RNA sequencing, and lineage tracing experiments point to selection of relatively low-affinity MBCs as a mechanism to promote diversity. Engineering immunogens to avoid this MBC diversity may facilitate flavivirus-type-specific vaccines with minimized potential for infection enhancement.Copyright © 2020 Elsevier Inc. All rights reserved.

    CD11b is a novel alternate receptor for CD154 during alloimmunity.

    In American Journal of Transplantation : Official Journal of the American Society of Transplantation and the American Society of Transplant Surgeons on 1 August 2020 by Liu, D. & Ford, M. L.

    PubMed

    Antagonism of the CD154/CD40 pathway is a highly effective means of inducing long-term graft survival in preclinical models. Using a fully allogeneic murine transplant model, we found that CD154 blockade was more effective in prolonging graft survival than was CD40 blockade, raising the possibility that CD154 binds a second receptor. To test this, we queried the impact of CD154 antagonism in the absence of CD40. Data indicated that anti-CD154 functioned to reduce graft-infiltrating CD8+ T cells in both WT and CD40-/- hosts. Because it has recently been reported that CD154 can ligate CD11b, we addressed the impact of blocking CD154-CD11b interactions during transplantation. We utilized a specific peptide antagonist that prevents CD154 binding of CD11b but has no effect on CD154-CD40 interactions. CD154:CD11b antagonism significantly increased the efficacy of anti-CD40 in prolonging allograft survival as compared to anti-CD40 plus control peptide. Mechanistically, CD154:CD11b antagonism functioned to reduce the frequency of graft-infiltrating CD8+ T cells and innate immune cells. These data therefore demonstrate that blocking CD154 interactions with both CD40 and CD11b is required for optimal inhibition of alloimmunity and provide an explanation for why CD40 blockers may be less efficacious than anti-CD154 reagents for the inhibition of allograft rejection. © 2020 The American Society of Transplantation and the American Society of Transplant Surgeons.

    • Cancer Research
    Cyto-Immuno-Therapy for Cancer: A Pathway Elicited by Tumor-Targeted, Cytotoxic Drug-Packaged Bacterially Derived Nanocells.

    In Cancer Cell on 16 March 2020 by Sagnella, S. M., Yang, L., et al.

    PubMed

    Immunotherapy has emerged as a powerful new chapter in the fight against cancer. However, it has yet to reach its full potential due in part to the complexity of the cancer immune response. We demonstrate that tumor-targeting EDV nanocells function as an immunotherapeutic by delivering a cytotoxin in conjunction with activation of the immune system. These nanocells polarize M1 macrophages and activate NK cells concurrently producing a Th1 cytokine response resulting in potent antitumor function. Dendritic cell maturation and antigen presentation follows, which generates tumor-specific CD8+ T cells, conferring prolonged tumor remission. The combination of cytotoxin delivery and activation of innate and adaptive antitumor immune responses results in a potent cyto-immunotherapeutic with potential in clinical oncology. Copyright © 2020 Elsevier Inc. All rights reserved.

    • Immunology and Microbiology
    Transfer of antigen-encoding bone marrow under immune-preserving conditions deletes mature antigen-specific B cells in recipients and inhibits antigen-specific antibody production

    Preprint on BioRxiv : the Preprint Server for Biology on 21 December 2019 by Brooks, J. F., Davies, J. M., et al.

    PubMed

    h4>Summary/h4> Pathological activation and collaboration of T and B cells underlies pathogenic autoantibody responses. Existing treatments for autoimmune disease cause non-specific immunosuppression and induction of antigen-specific tolerance remains an elusive goal. Many immunotherapies aim to manipulate the T-cell component of T-B interplay but few directly target B cells. One possible means to specifically target B cells is the transfer of gene-engineered BM that, once engrafted, gives rise to widespread specific and tolerogenic antigen expression within the hematopoietic system. Gene-engineered bone marrow encoding ubiquitous ovalbumin expression was transferred after low-dose (300cGy) immune-preserving irradiation. B-cell responsiveness was monitored by analyzing ovalbumin-specific antibody production after immunization with ovalbumin/complete Freund’s adjuvant. Ovalbumin-specific B cells and their response to immunization were analyzed using multi-tetramer staining. When antigen-encoding bone marrow was transferred under immune-preserving conditions, cognate antigen-specific B cells were purged from the recipient’s pre-existing B cell repertoire as well as the repertoire that arose after bone marrow transfer. OVA-specific B-cell deletion was apparent within the established host B-cell repertoire as well as that developing after gene-engineered bone marrow transfer. OVA-specific antibody production was substantially inhibited by transfer of OVA-encoding BM and activation of OVA-specific B cells, germinal centre formation and subsequent OVA-specific plasmablast differentiation were all inhibited. Low levels of gene-engineered bone marrow chimerism were sufficient to limit antigen-specific antibody production. These data show that antigen-specific B cells within an established B-cell repertoire are susceptible to de novo tolerance induction and this can be achieved by transfer of gene-engineered bone marrow. This adds further dimensions to the utility of antigen-encoding bone marrow transfer as an immunotherapeutic tool.

    • IHC-IF
    • ,
    • Homo sapiens (Human)
    • ,
    • Cancer Research
    • ,
    • Pathology
    Myeloid-Derived Lymphatic Endothelial Cell Progenitors Significantly Contribute to Lymphatic Metastasis in Clinical Breast Cancer.

    In The American Journal of Pathology on 1 November 2019 by Volk-Draper, L., Patel, R., et al.

    PubMed

    Lymphatic metastasis is a high-impact prognostic factor for mortality of breast cancer (BC) patients, and it directly depends on tumor-associated lymphatic vessels. We previously reported that lipopolysaccharide-induced inflammatory lymphangiogenesis is strongly promoted by myeloid-derived lymphatic endothelial cell progenitors (M-LECPs) derived from the bone marrow (BM). As BC recruits massive numbers of provascular myeloid cells, we hypothesized that M-LECPs, within this recruited population, are specifically programmed to promote tumor lymphatics that increase lymph node metastasis. In support of this hypothesis, high levels of M-LECPs were found in peripheral blood and tumor tissues of BC patients. Moreover, the density of M-LECPs and lymphatic vessels positive for myeloid marker proteins strongly correlated with patient node status. It was also established that tumor M-LECPs coexpress lymphatic-specific, stem/progenitor and M2-type macrophage markers that indicate their BM hematopoietic-myeloid origin and distinguish them from mature lymphatic endothelial cells, tumor-infiltrating lymphoid cells, and tissue-resident macrophages. Using four orthotopic BC models, we show that mouse M-LECPs are similarly recruited to tumors and integrate into preexisting lymphatics. Finally, we demonstrate that adoptive transfer of in vitro differentiated M-LECPs, but not naïve or nondifferentiated BM cells, significantly increased metastatic burden in ipsilateral lymph nodes. These data support a causative role of BC-induced lymphatic progenitors in tumor lymphangiogenesis and suggest molecular targets for their inhibition. Copyright © 2019 American Society for Investigative Pathology. Published by Elsevier Inc. All rights reserved.

    • Mus musculus (House mouse)
    Light-sheet microscopy in the near-infrared II window.

    In Nature Methods on 1 June 2019 by Wang, F., Wan, H., et al.

    PubMed

    Non-invasive deep-tissue three-dimensional optical imaging of live mammals with high spatiotemporal resolution is challenging owing to light scattering. We developed near-infrared II (1,000-1,700 nm) light-sheet microscopy with excitation and emission of up to approximately 1,320 nm and 1,700 nm, respectively, for optical sectioning at a penetration depth of approximately 750 μm through live tissues without invasive surgery and at a depth of approximately 2 mm in glycerol-cleared brain tissues. Near-infrared II light-sheet microscopy in normal and oblique configurations enabled in vivo imaging of live mice through intact tissue, revealing abnormal blood flow and T-cell motion in tumor microcirculation and mapping out programmed-death ligand 1 and programmed cell death protein 1 in tumors with cellular resolution. Three-dimensional imaging through the intact mouse head resolved vascular channels between the skull and brain cortex, and allowed monitoring of recruitment of macrophages and microglia to the traumatic brain injury site.

    • MACS
    • ,
    • FC/FACS
    • ,
    • Mus musculus (House mouse)
    • ,
    • Immunology and Microbiology
    Live-cell imaging reveals the relative contributions of antigen-presenting cell subsets to thymic central tolerance.

    In Nature Communications on 17 May 2019 by Lancaster, J. N., Thyagarajan, H. M., et al.

    PubMed

    Both medullary thymic epithelial cells (mTEC) and dendritic cells (DC) present tissue-restricted antigens (TRA) to thymocytes to induce central tolerance, but the relative contributions of these antigen-presenting cell (APC) subsets remain unresolved. Here we developed a two-photon microscopy approach to observe thymocytes interacting with intact APCs presenting TRAs. We find that mTECs and DCs cooperate extensively to induce tolerance, with their relative contributions regulated by the cellular form of the TRA and the class of major histocompatibility complex (MHC) on which antigen is presented. Even when TRA expression is restricted to mTECs, DCs still present self-antigens at least as frequently as mTECs. Notably, the DC subset cDC2 efficiently acquires secreted mTEC-derived TRAs for cross-presentation on MHC-I. By directly imaging interactions between thymocytes and APCs, while monitoring intracellular signaling, this study reveals that distinct DC subsets and AIRE+ mTECs contribute substantially to presentation of diverse self-antigens for establishing central tolerance.

    • Genetics
    Regulation of invariant NKT cell development and function by a 0.14 Mbp locus on chromosome 1: a possible role for Fcgr3.

    In Genes and Immunity on 1 April 2019 by DeVault, V. L., Malagic, M., et al.

    PubMed

    Invariant NKT (iNKT) cells are tissue-resident innate-like T cells critical to the host immune response. We previously identified a 6.6 Mbp region on chromosome 1 as a major regulator of iNKT cell number and function in C57BL/6 and 129X1/SvJ mice. Here, we fine-mapped this locus by assessing the iNKT cell response to alpha-galactosylceramide (αGalCer) in a series of B6.129 congenic lines. This analysis revealed the presence of at least two genetic elements that regulate iNKT cell cytokine production in response to αGalCer. While one of these genetic elements mapped to the B6.129c6 interval containing Slam genes, the dominant regulator in this region mapped to the 0.14 Mbp B6.129c3 interval. In addition, we found that numbers of thymic iNKT cells and DP thymocytes were significantly lower in B6.129c3 mice, indicating that this interval also regulates iNKT cell development. Candidate gene analysis revealed a fivefold increase in Fcgr3 expression in B6.129c3 iNKT cells, and we observed increased expression of FcγR3 protein on B6.129c3 iNKT cells, NK cells, and neutrophils. These data identify the B6.129c3 interval as a novel locus regulating the response of iNKT cells to glycosphingolipid, revealing a link between this phenotype and a polymorphism that regulates Fcgr3 expression.

    Myeloid-Derived Suppressor Cells Produce IL-10 to Elicit DNMT3b-Dependent IRF8 Silencing to Promote Colitis-Associated Colon Tumorigenesis.

    In Cell Reports on 11 December 2018 by Ibrahim, M. L., Klement, J. D., et al.

    PubMed

    IL-10 functions as a suppressor of colitis and colitis-associated colon cancer, but it is also a risk locus associated with ulcerative colitis. The mechanism underlying the contrasting roles of IL-10 in inflammation and colon cancer is unknown. We report here that inflammation induces the accumulation of CD11b+Gr1+ myeloid-derived suppressor cells (MDSCs) that express high levels of IL-10 in colon tissue. IL-10 induces the activation of STAT3 that directly binds to the Dnmt1 and Dnmt3b promoters to activate their expression, resulting in DNA hypermethylation at the Irf8 promoter to silence IRF8 expression in colon epithelial cells. Mice with Irf8 deleted in colonic epithelial cells exhibit significantly higher inflammation-induced tumor incidence. Human colorectal carcinomas have significantly higher DNMT1 and DNMT3b and lower IRF8 expression, and they exhibit significantly higher IRF8 promoter DNA methylation than normal colon. Our data identify the MDSC-IL-10-STAT3-DNMT3b-IRF8 pathway as a link between chronic inflammation and colon cancer initiation. Copyright © 2018 The Author(s). Published by Elsevier Inc. All rights reserved.

    • Cancer Research
    Myeloid-derived macrophages and secreted HSP90α induce pancreatic ductal adenocarcinoma development.

    In Oncoimmunology on 4 May 2018 by Chen, C. C., Chen, L. L., et al.

    PubMed

    We detected a significant elevation of serum HSP90α levels in pancreatitis patients and even more in pancreatic ductal adenocarcinoma (PDAC) patients. However, there was no significant difference in the serum HSP90α levels between patients with early-stage and late-stage PDAC. To study whether elevation of serum HSP90α levels occurred early during PDAC development, we used LSL-KrasG12D/Pdx1-Cre transgenic mice as a studying model. Elevated serum HSP90α levels were detected before PDAC formation and an extracellular HSP90α (eHSP90α) inhibitor effectively prevented PDAC development. Both serum HSP90α level and pancreatic lesion were suppressed when the mice were administered a CD11b-antagonizing antibody, suggesting that CD11b+-myeloid cells were associated with eHSP90α levels and pancreatic carcinogenesis. Consistently, in CD11b-DTR-EGFP transgenic mouse model with CD11b+-myeloid cells depletion, serum HSP90α levels were suppressed and Panc-02 cell grafts failed to develop tumors. Macrophages and granulocytes are two common tissue-infiltrating CD11b+-myeloid cells. Duplex in situ hybridization assays suggested that macrophages were predominant HSP90α-expressing CD11b+-myeloid cells during PDAC development. Immunohistochemical and immunohistofluorescent staining results revealed that HSP90α-expressing cells included not only macrophages but also pancreatic ductal epithelial (PDE) cells. Cell culture studies also indicated that eHSP90α could be produced by macrophages and macrophage-stimulated PDE cells. Macrophages not only secreted significant amount of HSP90α, but also secreted interleukin-6 and interleukin-8 to induce a JAK2-STAT3 signaling axis in PDE cells, stimulating them to express and secrete HSP90α. eHSP90α further promoted cellular epithelial-mesenchymal transition, migration, and invasion in PDE cells. Besides myeloid cells, eHSP90α can be potentially taken as a target to suppress PDAC pathogenesis.

    • Immunology and Microbiology
    Epidermal Growth Factor Receptor Expression Licenses Type-2 Helper T Cells to Function in a T Cell Receptor-Independent Fashion.

    In Immunity on 17 October 2017 by Minutti, C. M., Drube, S., et al.

    PubMed

    Gastro-intestinal helminth infections trigger the release of interleukin-33 (IL-33), which induces type-2 helper T cells (Th2 cells) at the site of infection to produce IL-13, thereby contributing to host resistance in a T cell receptor (TCR)-independent manner. Here, we show that, as a prerequisite for IL-33-induced IL-13 secretion, Th2 cells required the expression of the epidermal growth factor receptor (EGFR) and of its ligand, amphiregulin, for the formation of a signaling complex between T1/ST2 (the IL-33R) and EGFR. This shared signaling complex allowed IL-33 to induce the EGFR-mediated activation of the MAP-kinase signaling pathway and consequently the expression of IL-13. Lack of EGFR expression on T cells abrogated IL-13 expression in infected tissues and impaired host resistance. EGFR expression on Th2 cells was TCR-signaling dependent, and therefore, our data reveal a mechanism by which antigen presentation controls the innate effector function of Th2 cells at the site of inflammation. Copyright © 2017 The Author(s). Published by Elsevier Inc. All rights reserved.

    • Immunology and Microbiology
    • ,
    • Neuroscience
    • ,
    • Pathology
    Stimulation of TLR4 Attenuates Alzheimer's Disease-Related Symptoms and Pathology in Tau-Transgenic Mice.

    In The Journal of Immunology on 15 October 2016 by Qin, Y., Liu, Y., et al.

    PubMed

    Alzheimer's disease (AD) is characterized by intracellular neurofibrillary tangles. The primary component, hyperphosphorylated Tau (p-Tau), contributes to neuronal death. Recent studies have shown that autophagy efficiently degrades p-Tau, but the mechanisms modulating autophagy and subsequent p-Tau clearance in AD remain unclear. In our study, we first analyzed the relationship between the inflammatory activation and autophagy in brains derived from aged mice and LPS-injected inflammatory mouse models. We found that inflammatory activation was essential for activation of autophagy in the brain, which was neuronal ATG5-dependent. Next, we found that autophagy in cultured neurons was enhanced by LPS treatment of cocultured macrophages. In further experiments designed to provoke chronic mild stimulation of TLR4 without inducing obvious neuroinflammation, we gave repeated LPS injections (i.p., 0.15 mg/kg, weekly for 3 mo) to transgenic mice overexpressing human Tau mutant (P301S) in neurons. We observed significant enhancement of neuronal autophagy, which was associated with a reduction of cerebral p-Tau proteins and improved cognitive function. In summary, these results show that neuroinflammation promotes neuronal autophagy and that chronic mild TLR4 stimulation attenuates AD-related tauopathy, likely by activating neuronal autophagy. Our study displays the beneficial face of neuroinflammation and suggests a possible role in the treatment of AD patients. Copyright © 2016 by The American Association of Immunologists, Inc.

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