ABSTRACT
Human cytomegalovirus (CMV) causes a wide array of disease to diverse populations of immune-compromised individuals. Thus, a more comprehensive understanding of how CMV enters numerous host cell types is necessary to further delineate the complex nature of CMV pathogenesis and to develop targeted therapeutics. To that end, we establish a vaccination strategy utilizing membrane vesicles derived from epithelial cells to generate a library of monoclonal antibodies (mAbs) targeting cell surface proteins in their native conformation. A high-throughput inhibition assay is employed to screen these antibodies for their ability to limit infection, and mAbs targeting CD46 are identified. In addition, a significant reduction of viral proliferation in CD46-KO epithelial cells confirms a role for CD46 function in viral dissemination. Further, we demonstrate a CD46-dependent entry pathway of virus infection in trophoblasts, but not in fibroblasts, highlighting the complexity of CMV entry and identifying CD46 as an entry factor in congenital infection.
Subject(s)
Cytomegalovirus Infections/immunology , Cytomegalovirus/immunology , Host-Pathogen Interactions/immunology , Membrane Cofactor Protein/immunology , Virus Internalization , Antibodies, Monoclonal/administration & dosage , Antibodies, Monoclonal/immunology , Antibodies, Neutralizing/administration & dosage , Antibodies, Neutralizing/immunology , Antibodies, Viral/administration & dosage , Antibodies, Viral/immunology , Cell Line , Cytomegalovirus Infections/prevention & control , Cytomegalovirus Infections/virology , Epithelial Cells/immunology , Epithelial Cells/virology , Fibroblasts/immunology , Fibroblasts/virology , Gene Knockout Techniques , Humans , Membrane Cofactor Protein/genetics , RNA, Small Interfering/metabolism , Trophoblasts/immunology , Trophoblasts/virology , Viral Vaccines/administration & dosage , Viral Vaccines/immunologyABSTRACT
Tumor-associated myeloid cells maintain immunosuppressive microenvironments within tumors. Identification of myeloid-specific receptors to modulate tumor-associated macrophage and myeloid-derived suppressor cell (MDSC) functions remains challenging. The leukocyte immunoglobulin-like receptor B (LILRB) family members are negative regulators of myeloid cell activation. We investigated how LILRB targeting could modulate tumor-associated myeloid cell function. LILRB2 antagonism inhibited receptor-mediated activation of SHP1/2 and enhanced proinflammatory responses. LILRB2 antagonism also inhibited AKT and STAT6 activation in the presence of M-CSF and IL-4. Transcriptome analysis revealed that LILRB2 antagonism altered genes involved in cell cytoskeleton remodeling, lipid/cholesterol metabolism, and endosomal sorting pathways, as well as changed differentiation gene networks associated with inflammatory myeloid cells as opposed to their alternatively activated phenotype. LILRB2 blockade effectively suppressed granulocytic MDSC and Treg infiltration and significantly promoted in vivo antitumor effects of T cell immune checkpoint inhibitors. Furthermore, LILRB2 blockade polarized tumor-infiltrating myeloid cells from non-small cell lung carcinoma tumor tissues toward an inflammatory phenotype. Our studies suggest that LILRB2 can potentially act as a myeloid immune checkpoint by reprogramming tumor-associated myeloid cells and provoking antitumor immunity.
