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Antibody-secreting macrophages generated using CpG-free plasmid eliminate tumor cells through antibody-dependent cellular phagocytosis.

ABSTRACT: The non-viral delivery of genes into macrophages, known as hard-to-transfect cells, is a challenge. In this study, the microporation of a CpG-free and small plasmid (pCGfd-GFP) showed high transfection efficiency, sustainable transgene expression, and good cell viability in the transfections of Raw 264.7 and primary bone marrow-derived macrophages. The non-viral method using the pCGfd vector encoding anti-EGFR single-chain Fv fused with Fc (scFv-Fc) generated the macrophages secreting anti-EGFR scFv-Fc. These macrophages effectively phagocytized tumor cells expressing EGFR through the antibody-dependent mechanism, as was proved by experiments using EGFR-knockout tumor cells. Finally, peri-tumoral injections of anti-EGFR scFv-Fc-secreting macrophages were shown to inhibit tumor growth in the xenograft mouse model. [BMB Reports 2020; 53(8): 442-447].

SUBMITTER: Cha EB

PROVIDER: S-EPMC7473480 | biostudies-literature | 2020 Aug

REPOSITORIES: biostudies-literature

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Antibody-secreting macrophages generated using CpG-free plasmid eliminate tumor cells through antibody-dependent cellular phagocytosis.

Cha Eun Bi EB Shin Keun Koo KK Seo Jinho J Oh Doo-Byoung DB

BMB reports 20200801 8

The non-viral delivery of genes into macrophages, known as hard-to-transfect cells, is a challenge. In this study, the microporation of a CpG-free and small plasmid (pCGfd-GFP) showed high transfection efficiency, sustainable transgene expression, and good cell viability in the transfections of Raw 264.7 and primary bone marrow-derived macrophages. The non-viral method using the pCGfd vector encoding anti-EGFR single-chain Fv fused with Fc (scFv-Fc) generated the macrophages secreting anti-EGFR ...[more]

PMID: 32438971

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Antibody-Dependent Cellular Phagocytosis by Macrophages is a Novel Mechanism of Action of Elotuzumab.

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| S-EPMC6030488 | biostudies-literature

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| S-EPMC3904600 | biostudies-literature

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| S-EPMC4058906 | biostudies-other

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CD47 blockade augmentation of trastuzumab antitumor efficacy dependent on antibody-dependent cellular phagocytosis.

Project description:The HER2-specific monoclonal antibody (mAb), trastuzumab, has been the mainstay of therapy for HER2+ breast cancer (BC) for approximately 20 years. However, its therapeutic mechanism of action (MOA) remains unclear, with antitumor responses to trastuzumab remaining heterogeneous and metastatic HER2+ BC remaining incurable. Consequently, understanding its MOA could enable rational strategies to enhance its efficacy. Using both murine and human versions of trastuzumab, we found its antitumor activity dependent on Fcγ receptor stimulation of tumor-associated macrophages (TAMs) and antibody-dependent cellular phagocytosis (ADCP), but not cellular cytotoxicity (ADCC). Trastuzumab also stimulated TAM activation and expansion, but did not require adaptive immunity, natural killer cells, and/or neutrophils. Moreover, inhibition of the innate immune ADCP checkpoint, CD47, significantly enhanced trastuzumab-mediated ADCP and TAM expansion and activation, resulting in the emergence of a unique hyperphagocytic macrophage population, improved antitumor responses, and prolonged survival. In addition, we found that tumor-associated CD47 expression was inversely associated with survival in HER2+ BC patients and that human HER2+ BC xenografts treated with trastuzumab plus CD47 inhibition underwent complete tumor regression. Collectively, our study identifies trastuzumab-mediated ADCP as an important antitumor MOA that may be clinically enabled by CD47 blockade to augment therapeutic efficacy.

| S-EPMC6975273 | biostudies-literature

FcγRII-binding Centyrins mediate agonism and antibody-dependent cellular phagocytosis when fused to an anti-OX40 antibody.

Project description:Immunostimulatory antibodies against the tumor necrosis factor receptors (TNFR) are emerging as promising cancer immunotherapies. The agonism activity of such antibodies depends on crosslinking to Fc gamma RIIB receptor (FcγRIIB) to enable the antibody multimerization that drives TNFR activation. Previously, Fc engineering was used to enhance the binding of such antibodies to Fcγ receptors. Here, we report the identification of Centyrins as alternative scaffold proteins with binding affinities to homologous FcγRIIB and FcγRIIA, but not to other types of Fcγ receptors. One Centyrin, S29, was engineered at distinct positions of an anti-OX40 SF2 antibody to generate bispecific and tetravalent molecules named as mAbtyrins. Regardless of the position of S29 on the SF2 antibody, SF2-S29 mAbtyrins could bind FcγRIIB and FcγRIIA specifically while maintaining binding to OX40 receptors. In a NFκB reporter assay, attachment of S29 Centyrin molecules at the C-termini, but not the N-termini, resulted in SF2 antibodies with increased agonism owing to FcγRIIB crosslinking. The mAbtyrins also showed agonism in T-cell activation assays with immobilized FcγRIIB and FcγRIIA, but this activity was confined to mAbtyrins with S29 specifically at the C-termini of antibody heavy chains. Furthermore, regardless of the position of the molecule, S29 Centyrin could equip an otherwise Fc-silent antibody with antibody-dependent cellular phagocytosis activity without affecting the antibody's intrinsic antibody-dependent cell-meditated cytotoxicity and complement-dependent cytotoxicity. In summary, the appropriate adoption FcγRII-binding Centyrins as functional modules represents a novel strategy to engineer therapeutic antibodies with improved functionalities.

| S-EPMC5916553 | biostudies-literature

Analysis and Fine Specificity of the HCMV-Specific Cell-Free and Cell-Associated Antibody-Dependent Cellular Phagocytosis (ADCP) Responses in Lung Transplant Recipients.

Project description:Human Cytomegalovirus (HCMV) may cause severe infections in transplant recipients. HCMV-replication can be limited by HCMV-specific antibody responses. The impact of the antibody-dependent cellular phagocytosis (ADCP) on inhibition of HCMV-replication in natural infections has not been clarified. Therefore, we investigated the HCMV-specific ADCP response in a study cohort of lung-transplant recipients (LTRs) with different donor (D) and recipient (R) HCMV-serostatus. Follow-up plasma samples from 39 non/low-viremic and 36 highly viremic (>1000 HCMV copies/mL plasma) LTRs were collected for one (R+ LTRs) or two (D+/R- LTRs) years post-transplantation. The HCMV-specific ADCP responses were assessed by focal expansion assays (FEA) and flow-cytometry. In all LTRs, ADCP responses were detected against HCMV-infected cells and cell-free virions. When measured in fibroblasts as well as with cell-free virus, the HCMV-specific ADPC response was higher in LTRs than in HCMV-seropositive healthy controls. In D+/R- LTRs, a significant ADCP response developed over time after the receipt of an HCMV positive lung, and a level of <19 IE+ cells/focus in the FEA on fibroblasts was associated with further protection from high-level viremia. Taken together, a strong HCMV-specific ADCP response is elicited in transplant recipients, which may contribute to protection from high-level viremia in primary HCMV infection.

| S-EPMC8348747 | biostudies-literature

CD47 blockade augmentation of Trastuzumab antitumor efficacy dependent upon antibody-dependent-cellular-phagocytosis

Project description:Analysis of HER2 breast tumor immune infiltrates in mice treated with murine Trastuzumab and CD47 checkpoint blockade therapy

2019-10-29 | GSE139492 | GEO

Diversity, cellular origin and autoreactivity of antibody-secreting cell population expansions in acute systemic lupus erythematosus.

Project description:Acute systemic lupus erythematosus (SLE) courses with surges of antibody-secreting cells (ASCs) whose origin, diversity and contribution to serum autoantibodies remain unknown. Here, deep sequencing, proteomic profiling of autoantibodies and single-cell analysis demonstrated highly diversified ASCs punctuated by clones expressing the variable heavy-chain region VH4-34 that produced dominant serum autoantibodies. A fraction of ASC clones contained autoantibodies without mutation, a finding consistent with differentiation outside the germinal centers. A substantial ASC segment was derived from a distinct subset of newly activated naive cells of considerable clonality that persisted in the circulation for several months. Thus, selection of SLE autoreactivities occurred during polyclonal activation, with prolonged recruitment of recently activated naive B cells. Our findings shed light on the pathogenesis of SLE, help explain the benefit of agents that target B cells and should facilitate the design of future therapies.

| S-EPMC4512288 | biostudies-literature

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