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1.
Nat Rev Drug Discov ; 21(1): 60-78, 2022 01.
Article in English | MEDLINE | ID: covidwho-2008294

ABSTRACT

Integrins are cell adhesion and signalling proteins crucial to a wide range of biological functions. Effective marketed treatments have successfully targeted integrins αIIbß3, α4ß7/α4ß1 and αLß2 for cardiovascular diseases, inflammatory bowel disease/multiple sclerosis and dry eye disease, respectively. Yet, clinical development of others, notably within the RGD-binding subfamily of αv integrins, including αvß3, have faced significant challenges in the fields of cancer, ophthalmology and osteoporosis. New inhibitors of the related integrins αvß6 and αvß1 have recently come to the fore and are being investigated clinically for the treatment of fibrotic diseases, including idiopathic pulmonary fibrosis and nonalcoholic steatohepatitis. The design of integrin drugs may now be at a turning point, with opportunities to learn from previous clinical trials, to explore new modalities and to incorporate new findings in pharmacological and structural biology. This Review intertwines research from biological, clinical and medicinal chemistry disciplines to discuss historical and current RGD-binding integrin drug discovery, with an emphasis on small-molecule inhibitors of the αv integrins.


Subject(s)
Integrins/antagonists & inhibitors , Integrins/metabolism , Small Molecule Libraries/pharmacology , Small Molecule Libraries/therapeutic use , Animals , Drug Discovery/methods , Humans , Protein Binding/drug effects
2.
Molecules ; 27(15)2022 Aug 04.
Article in English | MEDLINE | ID: covidwho-1994117

ABSTRACT

Targeting cells specifically based on receptor expression levels remains an area of active research to date. Selective binding of receptors cannot be achieved by increasing the individual binding strength, as this does not account for differing distributions of receptor density across healthy and diseased cells. Engaging receptors above a threshold concentration would be desirable in devising selective diagnostics. Integrins are prime target candidates as they are readily available on the cell surface and have been reported to be overexpressed in diseases. Insights into their spatial organization would therefore be advantageous to design selective targeting agents. Here, we investigated the effect of activation method on integrin α5ß1 clustering by immunofluorescence and modeled the global neighbor distances with input from an immuno-staining assay and image processing of microscopy images. This data was used to engineer spatially-controlled DNA-scaffolded bivalent ligands, which we used to compare trends in spatial-selective binding observed across HUVEC, CHO and HeLa in resting versus activated conditions in confocal microscopy images. For HUVEC and CHO, the data demonstrated an improved selectivity and localisation of binding for smaller spacings ~7 nm and ~24 nm, in good agreement with the model. A deviation from the mode predictions for HeLa was observed, indicative of a clustered, instead of homogeneous, integrin organization. Our findings demonstrate how low-technology imaging methods can guide the design of spatially controlled ligands to selectively differentiate between cell type and integrin activation state.


Subject(s)
Integrin alpha5beta1 , Nanoparticles , DNA , Integrin alpha5beta1/metabolism , Integrins/metabolism , Ligands
4.
Cells ; 11(10)2022 05 19.
Article in English | MEDLINE | ID: covidwho-1862726

ABSTRACT

Most cells express several integrins. The integrins are able to respond to various cellular functions and needs by modifying their own activation state, but in addition by their ability to regulate each other by activation or inhibition. This crosstalk or transdominant regulation is strictly controlled. The mechanisms resulting in integrin crosstalk are incompletely understood, but they often involve intracellular signalling routes also used by other cell surface receptors. Several studies show that the integrin cytoplasmic tails bind to a number of cytoskeletal and adaptor molecules in a regulated manner. Recent work has shown that phosphorylations of integrins and key intracellular molecules are of pivotal importance in integrin-cytoplasmic interactions, and these in turn affect integrin activity and crosstalk. The integrin ß-chains play a central role in regulating crosstalk. In addition to Integrin-integrin crosstalk, crosstalk may also occur between integrins and related receptors, including other adhesion receptors, growth factor and SARS-CoV-2 receptors.


Subject(s)
COVID-19 , Integrins , Cell Adhesion , Cytoplasm/metabolism , Humans , Integrins/metabolism , SARS-CoV-2
5.
Adv Healthc Mater ; 11(14): e2200283, 2022 07.
Article in English | MEDLINE | ID: covidwho-1843840

ABSTRACT

The eye is susceptible to viral infections, causing severe ocular symptoms or even respiratory diseases. Methods capable of protecting the eye from external viral invasion in a long-term and highly effective way are urgently needed but have been proved to be extremely challenging. Here, a strategy of forming a long-acting protective ocular surface is described by instilling adhesive dual-antiviral nanoparticles. Taking pseudotyped severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) as a model virus, antiviral agent-loaded nanoparticles are coated with a "double-lock" hybrid cell membrane abundant with integrin-ß1 and angiotensin converting enzyme II (ACE2). After instillation, the presence of integrin-ß1 endows coated nanoparticles with steady adhesion via specific binding to Arg-Gly-Asp sequence on the fibronectin of ocular epithelium, achieving durable retention on the ocular surface. In addition to loaded inhibitors, the exposure of ACE2 can trap SARS-CoV-2 and subsequently neutralize the associated spike protein, playing a dual antiviral effect of the resulting nanoparticles. Adhesive dual-antiviral nanoparticles enabled by coating with a "double-lock" hybrid cell membrane could be a versatile platform for topical long-acting protection against viral infection of the eye.


Subject(s)
Antiviral Agents , COVID-19 , Eye Diseases , Eye , Nanoparticles , Adhesives/pharmacology , Angiotensin-Converting Enzyme 2 , Antiviral Agents/pharmacology , COVID-19/drug therapy , Eye/drug effects , Eye/virology , Eye Diseases/prevention & control , Eye Diseases/virology , Humans , Integrins , SARS-CoV-2
6.
J Biol Chem ; 298(3): 101710, 2022 03.
Article in English | MEDLINE | ID: covidwho-1670670

ABSTRACT

Coronavirus disease 2019 (COVID-19) is a highly contagious disease caused by severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2). It is broadly accepted that SARS-CoV-2 utilizes its spike protein to recognize the extracellular domain of angiotensin-converting enzyme 2 (ACE2) to enter cells for viral infection. However, other mechanisms of SARS-CoV-2 cell entry may occur. We show quantitatively that the SARS-CoV-2 spike protein also binds to the extracellular domain of broadly expressed integrin α5ß1 with an affinity comparable to that of SARS-CoV-2 binding to ACE2. More importantly, we provide direct evidence that such binding promotes the internalization of SARS-CoV-2 into non-ACE2 cells in a manner critically dependent upon the activation of the integrin. Our data demonstrate an alternative pathway for the cell entry of SARS-CoV-2, suggesting that upon initial ACE2-mediated invasion of the virus in the respiratory system, which is known to trigger an immune response and secretion of cytokines to activate integrin, the integrin-mediated cell invasion of SARS-CoV-2 into the respiratory system and other organs becomes effective, thereby promoting further infection and progression of COVID-19.


Subject(s)
COVID-19 , SARS-CoV-2 , Spike Glycoprotein, Coronavirus , Virus Internalization , Angiotensin-Converting Enzyme 2/genetics , Angiotensin-Converting Enzyme 2/metabolism , COVID-19/metabolism , COVID-19/virology , Humans , Integrins/metabolism , Protein Binding , SARS-CoV-2/metabolism , SARS-CoV-2/physiology , Spike Glycoprotein, Coronavirus/metabolism
8.
Front Cell Infect Microbiol ; 11: 765300, 2021.
Article in English | MEDLINE | ID: covidwho-1555151

ABSTRACT

The RGD motif in the Severe Acute Syndrome Coronavirus 2 (SARS-CoV-2) spike protein has been predicted to bind RGD-recognizing integrins. Recent studies have shown that the spike protein does, indeed, interact with αVß3 and α5ß1 integrins, both of which bind to RGD-containing ligands. However, computational studies have suggested that binding between the spike RGD motif and integrins is not favourable, even when unfolding occurs after conformational changes induced by binding to the canonical host entry receptor, angiotensin-converting enzyme 2 (ACE2). Furthermore, non-RGD-binding integrins, such as αx, have been suggested to interact with the SARS-CoV-2 spike protein. Other viral pathogens, such as rotaviruses, have been recorded to bind integrins in an RGD-independent manner to initiate host cell entry. Thus, in order to consider the potential for the SARS-CoV-2 spike protein to bind integrins independent of the RGD sequence, we investigate several factors related to the involvement of integrins in SARS-CoV-2 infection. First, we review changes in integrin expression during SARS-CoV-2 infection to identify which integrins might be of interest. Then, all known non-RGD integrin-binding motifs are collected and mapped to the spike protein receptor-binding domain and analyzed for their 3D availability. Several integrin-binding motifs are shown to exhibit high sequence similarity with solvent accessible regions of the spike receptor-binding domain. Comparisons of these motifs with other betacoronavirus spike proteins, such as SARS-CoV and RaTG13, reveal that some have recently evolved while others are more conserved throughout phylogenetically similar betacoronaviruses. Interestingly, all of the potential integrin-binding motifs, including the RGD sequence, are conserved in one of the known pangolin coronavirus strains. Of note, the most recently recorded mutations in the spike protein receptor-binding domain were found outside of the putative integrin-binding sequences, although several mutations formed inside and close to one motif, in particular, may potentially enhance binding. These data suggest that the SARS-CoV-2 spike protein may interact with integrins independent of the RGD sequence and may help further explain how SARS-CoV-2 and other viruses can evolve to bind to integrins.


Subject(s)
COVID-19 , Spike Glycoprotein, Coronavirus , Cell Line , Humans , Integrins , Membrane Glycoproteins , Oligopeptides , Peptidyl-Dipeptidase A , SARS-CoV-2 , Spike Glycoprotein, Coronavirus/genetics , Viral Envelope Proteins
9.
Trends Biochem Sci ; 47(3): 265-278, 2022 03.
Article in English | MEDLINE | ID: covidwho-1550091

ABSTRACT

Cell adhesion is essential for the formation of organs, cellular migration, and interaction with target cells and the extracellular matrix. Integrins are large protein α/ß-chain heterodimers and form a major family of cell adhesion molecules. Recent research has dramatically increased our knowledge of how integrin phosphorylations regulate integrin activity. Phosphorylations determine the signaling complexes formed on the cytoplasmic tails, regulating downstream signaling. α-Chain phosphorylation is necessary for inducing ß-chain phosphorylation in LFA-1, and the crosstalk from one integrin to another activating or inactivating its function is in part mediated by phosphorylation of ß-chains. The severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) virus receptor angiotensin-converting enzyme 2 (ACE2) and possible integrin coreceptors may crosstalk and induce a phosphorylation switch and autophagy.


Subject(s)
COVID-19 , Integrins , Cell Adhesion , Humans , Integrins/metabolism , Phosphorylation , SARS-CoV-2
10.
Front Immunol ; 12: 689866, 2021.
Article in English | MEDLINE | ID: covidwho-1503883

ABSTRACT

Rapid recruitment of neutrophils to an inflamed site is one of the hallmarks of an effective host defense mechanism. The main pathway through which this happens is by the innate immune response. Neutrophils, which play an important part in innate immune defense, migrate into lungs through the modulation actions of chemokines to execute a variety of pro-inflammatory functions. Despite the importance of chemokines in host immunity, little has been discussed on their roles in host immunity. A holistic understanding of neutrophil recruitment, pattern recognition pathways, the roles of chemokines and the pathophysiological roles of neutrophils in host immunity may allow for new approaches in the treatment of infectious and inflammatory disease of the lung. Herein, this review aims at highlighting some of the developments in lung neutrophil-immunity by focusing on the functions and roles of CXC/CC chemokines and pattern recognition receptors in neutrophil immunity during pulmonary inflammations. The pathophysiological roles of neutrophils in COVID-19 and thromboembolism have also been summarized. We finally summarized various neutrophil biomarkers that can be utilized as prognostic molecules in pulmonary inflammations and discussed various neutrophil-targeted therapies for neutrophil-driven pulmonary inflammatory diseases.


Subject(s)
Immunity, Innate/immunology , Neutrophils/immunology , Pneumonia/immunology , Biomarkers/blood , COVID-19/immunology , Cell Degranulation/immunology , Chemokines/immunology , Clinical Trials as Topic , Extracellular Traps/immunology , Humans , Integrins/immunology , Lung/immunology , Lung/pathology , Neutrophils/drug effects , Pneumonia/diagnosis , Pneumonia/drug therapy , Receptors, Pattern Recognition/immunology , Respiratory Burst/immunology , SARS-CoV-2 , Thromboembolism/immunology
11.
Sci Rep ; 11(1): 20398, 2021 10 14.
Article in English | MEDLINE | ID: covidwho-1469993

ABSTRACT

SARS-CoV-2 infection depends on binding its spike (S) protein to angiotensin-converting enzyme 2 (ACE2). The S protein expresses an RGD motif, suggesting that integrins may be co-receptors. Here, we UV-inactivated SARS-CoV-2 and fluorescently labeled the envelope membrane with octadecyl rhodamine B (R18) to explore the role of integrin activation in mediating cell entry and productive infection. We used flow cytometry and confocal microscopy to show that SARS-CoV-2R18 particles engage basal-state integrins. Furthermore, we demonstrate that Mn2+, which induces integrin extension, enhances cell entry of SARS-CoV-2R18. We also show that one class of integrin antagonist, which binds to the αI MIDAS site and stabilizes the inactive, closed conformation, selectively inhibits the engagement of SARS-CoV-2R18 with basal state integrins, but is ineffective against Mn2+-activated integrins. RGD-integrin antagonists inhibited SARS-CoV-2R18 binding regardless of integrin activation status. Integrins transmit signals bidirectionally: 'inside-out' signaling primes the ligand-binding function of integrins via a talin-dependent mechanism, and 'outside-in' signaling occurs downstream of integrin binding to macromolecular ligands. Outside-in signaling is mediated by Gα13. Using cell-permeable peptide inhibitors of talin and Gα13 binding to the cytoplasmic tail of an integrin's ß subunit, we demonstrate that talin-mediated signaling is essential for productive infection.


Subject(s)
COVID-19/metabolism , Integrins/metabolism , SARS-CoV-2/physiology , Virus Internalization , Animals , Chlorocebus aethiops , Host-Pathogen Interactions , Humans , Signal Transduction , Vero Cells
12.
Blood ; 139(14): 2130-2144, 2022 04 07.
Article in English | MEDLINE | ID: covidwho-1457448

ABSTRACT

Modulation of neutrophil recruitment and function is crucial for targeting inflammatory cells to sites of infection to combat invading pathogens while, at the same time, limiting host tissue injury or autoimmunity. The underlying mechanisms regulating recruitment of neutrophils, 1 of the most abundant inflammatory cells, have gained increasing interest over the years. The previously described classical recruitment cascade of leukocytes has been extended to include capturing, rolling, adhesion, crawling, and transmigration, as well as a reverse-transmigration step that is crucial for balancing immune defense and control of remote organ endothelial leakage. Current developments in the field emphasize the importance of cellular interplay, tissue environmental cues, circadian rhythmicity, detection of neutrophil phenotypes, differential chemokine sensing, and contribution of distinct signaling components to receptor activation and integrin conformations. The use of therapeutics modulating neutrophil activation responses, as well as mutations causing dysfunctional neutrophil receptors and impaired signaling cascades, have been defined in translational animal models. Human correlates of such mutations result in increased susceptibility to infections or organ damage. This review focuses on current advances in the understanding of the regulation of neutrophil recruitment and functionality and translational implications of current discoveries in the field with a focus on acute inflammation and sepsis.


Subject(s)
Neutrophil Activation , Neutrophils , Animals , Humans , Inflammation , Integrins , Neutrophil Infiltration
13.
FEBS Lett ; 595(17): 2257-2270, 2021 09.
Article in English | MEDLINE | ID: covidwho-1439663

ABSTRACT

HIV preferentially infects α4 ß7 + CD4 T cells, forming latent reservoirs that contribute to HIV persistence during antiretroviral therapy. However, the properties of α4 ß7 + CD4 T cells in blood and mucosal compartments remain understudied. Employing two distinct models of HIV infection, HIV-infected humans and simian-human immunodeficiency virus (SHIV)-infected rhesus macaques, we show that α4 ß7 + CD4 T cells in blood are enriched for genes regulating cell cycle progression and cellular metabolism. Unlike their circulating counterparts, rectal α4 ß7 + CD4 T cells exhibited a core tissue-residency gene expression program. These features were conserved across primate species, indicating that the environment influences memory T-cell transcriptional networks. Our findings provide an important molecular foundation for understanding the role of α4 ß7 in HIV infection.


Subject(s)
CD4-Positive T-Lymphocytes/metabolism , CD4-Positive T-Lymphocytes/virology , HIV Infections/blood , Integrins/metabolism , Adult , Animals , COVID-19/blood , COVID-19/virology , Cell Cycle , Cell Proliferation , Gastric Mucosa/cytology , Gastric Mucosa/virology , Gene Expression Regulation , Humans , Immunization , Macaca mulatta , Male , Simian Acquired Immunodeficiency Syndrome/blood , Simian Acquired Immunodeficiency Syndrome/virology
14.
Int J Mol Sci ; 22(9)2021 Apr 27.
Article in English | MEDLINE | ID: covidwho-1390655

ABSTRACT

The identification of thrombospondin-1 as an angiogenesis inhibitor in 1990 prompted interest in its role in cancer biology and potential as a therapeutic target. Decreased thrombospondin-1 mRNA and protein expression are associated with progression in several cancers, while expression by nonmalignant cells in the tumor microenvironment and circulating levels in cancer patients can be elevated. THBS1 is not a tumor suppressor gene, but the regulation of its expression in malignant cells by oncogenes and tumor suppressor genes mediates some of their effects on carcinogenesis, tumor progression, and metastasis. In addition to regulating angiogenesis and perfusion of the tumor vasculature, thrombospondin-1 limits antitumor immunity by CD47-dependent regulation of innate and adaptive immune cells. Conversely, thrombospondin-1 is a component of particles released by immune cells that mediate tumor cell killing. Thrombospondin-1 differentially regulates the sensitivity of malignant and nonmalignant cells to genotoxic stress caused by radiotherapy and chemotherapy. The diverse activities of thrombospondin-1 to regulate autophagy, senescence, stem cell maintenance, extracellular vesicle function, and metabolic responses to ischemic and genotoxic stress are mediated by several cell surface receptors and by regulating the functions of several secreted proteins. This review highlights progress in understanding thrombospondin-1 functions in cancer and the challenges that remain in harnessing its therapeutic potential.


Subject(s)
Neoplasms , Thrombospondin 1/physiology , Tumor Microenvironment/physiology , Animals , Cell Adhesion , Cell Movement , Humans , Integrins/metabolism , Mice , Neoplasms/blood supply , Neoplasms/immunology , Neoplasms/pathology , Neovascularization, Pathologic/metabolism , Neovascularization, Physiologic/genetics , T-Lymphocytes/immunology , Thrombospondin 1/genetics , Thrombospondin 1/metabolism
16.
J Nucl Med ; 61(12): 1717-1719, 2020 12.
Article in English | MEDLINE | ID: covidwho-1369627

ABSTRACT

The true impact and long-term damage to organs such as the lungs after severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) infection remain to be determined. Noninvasive molecularly targeted imaging may play a critical role in aiding visualization and understanding of the systemic damage. We have identified αvß6 as a molecular target; an epithelium-specific cell surface receptor that is low or undetectable in healthy adult epithelium but upregulated in select injured tissues, including fibrotic lung. Herein we report the first human PET/CT images using the integrin αvß6-binding peptide (18F-αvß6-BP) in a patient 2 mo after the acute phase of infection. Minimal uptake of 18F-αvß6-BP was noted in normal lung parenchyma, with uptake being elevated in areas corresponding to opacities on CT. This case suggests that 18F-αvß6-BP PET/CT is a promising noninvasive approach to identify the presence and potentially monitor the persistence and progression of lung damage.


Subject(s)
Antigens, Neoplasm/metabolism , COVID-19/diagnostic imaging , COVID-19/metabolism , Integrins/metabolism , Lung/diagnostic imaging , Positron Emission Tomography Computed Tomography , Aged , Humans , Male
17.
Life Sci ; 284: 119881, 2021 Nov 01.
Article in English | MEDLINE | ID: covidwho-1347741

ABSTRACT

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) is an infectious disease that has spread worldwide. Current treatments are limited in both availability and efficacy, such that improving our understanding of the factors that facilitate infection is urgently needed to more effectively treat infected individuals and to curb the pandemic. We and others have previously demonstrated the significance of interactions between the SARS-CoV-2 spike protein, integrin α5ß1, and human ACE2 to facilitate viral entry into host cells in vitro. We previously found that inhibition of integrin α5ß1 by the clinically validated small peptide ATN-161 inhibits these spike protein interactions and cell infection in vitro. In continuation with our previous findings, here we have further evaluated the therapeutic potential of ATN-161 on SARS-CoV-2 infection in k18-hACE2 transgenic (SARS-CoV-2 susceptible) mice in vivo. We discovered that treatment with single or repeated intravenous doses of ATN-161 (1 mg/kg) within 48 h after intranasal inoculation with SARS-CoV-2 lead to a reduction of lung viral load, viral immunofluorescence, and improved lung histology in a majority of mice 72 h post-infection. Furthermore, ATN-161 reduced SARS-CoV-2-induced increased expression of lung integrin α5 and αv (an α5-related integrin that has also been implicated in SARS-CoV-2 interactions) as well as the C-X-C motif chemokine ligand 10 (Cxcl10), further supporting the potential involvement of these integrins, and the anti-inflammatory potential of ATN-161, respectively, in SARS-CoV-2 infection. To the best of our knowledge, this is the first study demonstrating the potential therapeutic efficacy of targeting integrin α5ß1 in SARS-CoV-2 infection in vivo and supports the development of ATN-161 as a novel SARS-CoV-2 therapy.


Subject(s)
Angiotensin-Converting Enzyme 2/metabolism , COVID-19/drug therapy , COVID-19/prevention & control , Oligopeptides/therapeutic use , SARS-CoV-2/physiology , Alanine Transaminase/metabolism , Animals , Aspartate Aminotransferases/metabolism , COVID-19/virology , Genome, Viral , Humans , Integrins/metabolism , Liver/enzymology , Liver/pathology , Lung/pathology , Lung/virology , Male , Mice, Inbred C57BL , Mice, Transgenic , Oligopeptides/pharmacology , SARS-CoV-2/genetics , Staining and Labeling , Viral Load/genetics
18.
J Infect ; 83(4): 496-522, 2021 10.
Article in English | MEDLINE | ID: covidwho-1313249
19.
Cells ; 10(7)2021 Jul 06.
Article in English | MEDLINE | ID: covidwho-1295777

ABSTRACT

Integrins belong to a group of cell adhesion molecules (CAMs) which is a large group of membrane-bound proteins. They are responsible for cell attachment to the extracellular matrix (ECM) and signal transduction from the ECM to the cells. Integrins take part in many other biological activities, such as extravasation, cell-to-cell adhesion, migration, cytokine activation and release, and act as receptors for some viruses, including severe acute respiratory syndrome-related coronavirus 2 (SARS-CoV-2). They play a pivotal role in cell proliferation, migration, apoptosis, tissue repair and are involved in the processes that are crucial to infection, inflammation and angiogenesis. Integrins have an important part in normal development and tissue homeostasis, and also in the development of pathological processes in the eye. This review presents the available evidence from human and animal research into integrin structure, classification, function and their role in inflammation, infection and angiogenesis in ocular diseases. Integrin receptors and ligands are clinically interesting and may be promising as new therapeutic targets in the treatment of some eye disorders.


Subject(s)
Eye Diseases/metabolism , Inflammation/metabolism , Integrins/metabolism , Neovascularization, Pathologic/metabolism , Animals , COVID-19/metabolism , COVID-19/pathology , Cell Adhesion , Extracellular Matrix/metabolism , Extracellular Matrix/pathology , Eye Diseases/pathology , Humans , Inflammation/pathology , Integrins/analysis , Neovascularization, Pathologic/pathology , SARS-CoV-2/metabolism
20.
PLoS Pathog ; 17(6): e1009662, 2021 06.
Article in English | MEDLINE | ID: covidwho-1259253

ABSTRACT

Signal-regulatory protein alpha (SIRPA) is a well-known inhibitor of phagocytosis when it complexes with CD47 expressed on target cells. Here we show that SIRPA decreased in vitro infection by a number of pathogenic viruses, including New World and Old World arenaviruses, Zika virus, vesicular stomatitis virus and pseudoviruses bearing the Machupo virus, Ebola virus and SARS-CoV-2 glycoproteins, but not HSV-1, MLV or mNoV. Moreover, mice with targeted mutation of the Sirpa gene that renders it non-functional were more susceptible to infection with the New World arenaviruses Junín virus vaccine strain Candid 1 and Tacaribe virus, but not MLV or mNoV. All SIRPA-inhibited viruses have in common the requirement for trafficking to a low pH endosomal compartment. This was clearly demonstrated with SARS-CoV-2 pseudovirus, which was only inhibited by SIRPA in cells in which it required trafficking to the endosome. Similar to its role in phagocytosis inhibition, SIRPA decreased virus internalization but not binding to cell surface receptors. We also found that increasing SIRPA levels via treatment with IL-4 led to even greater anti-viral activity. These data suggest that enhancing SIRPA's activity could be a target for anti-viral therapies.


Subject(s)
Endocytosis , RNA Viruses/immunology , Receptors, Immunologic/physiology , Virus Internalization , Animals , Antiviral Agents/pharmacology , Cell Line , Cell Membrane/virology , Chlorocebus aethiops , Drug Delivery Systems , Integrins/immunology , Interleukin-4/pharmacology , Mice , Mice, Knockout , Protein Domains , Receptors, Immunologic/genetics , Vero Cells
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