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Saccon E, Mikaeloff F, Figueras Ivern P, Végvári Á, Sönnerborg A, Neogi U, van Domselaar R. Cytotoxic Lymphocytes Target HIV-1 Gag Through Granzyme M-Mediated Cleavage. Front Immunol 2021; 12:669347. [PMID: 33953729 PMCID: PMC8089382 DOI: 10.3389/fimmu.2021.669347] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/18/2021] [Accepted: 03/31/2021] [Indexed: 11/13/2022] Open
Abstract
Untreated HIV-1 infection leads to a slow decrease in CD4+ T cell lymphocytes over time resulting in increased susceptibility to opportunistic infections (acquired immunodeficiency syndrome, AIDS) and ultimately death of the infected individual. Initially, the host's immune response controls the infection, but cannot eliminate the HIV-1 from the host. Cytotoxic lymphocytes are the key effector cells in this response and can mediate crucial antiviral responses through the release of a set of proteases called granzymes towards HIV-1-infected cells. However, little is known about the immunological molecular mechanisms by which granzymes could control HIV-1. Since we noted that HIV-1 subtype C (HIV-1C) Gag with the tetrapeptide insertion PYKE contains a putative granzyme M (GrM) cleavage site (KEPL) that overlaps with the PYKE insertion, we analyzed the proteolytic activity of GrM towards Gag. Immunoblot analysis showed that GrM could cleave Gag proteins from HIV-1B and variants from HIV-1C of which the Gag-PYKE variant was cleaved with extremely high efficiency. The main cleavage site was directly after the insertion after leucine residue 483. GrM-mediated cleavage of Gag was also observed in co-cultures using cytotoxic lymphocytes as effector cells and this cleavage could be inhibited by a GrM inhibitor peptide. Altogether, our data indicate towards a noncytotoxic immunological mechanism by which GrM-positive cytotoxic lymphocytes target the HIV-1 Gag protein within infected cells to potentially control HIV-1 infection. This mechanism could be exploited in new therapeutic strategies to treat HIV-1-infected patients to improve immunological control of the infection.
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Affiliation(s)
- Elisa Saccon
- Division of Clinical Microbiology, ANA Futura Laboratory, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Flora Mikaeloff
- Division of Clinical Microbiology, ANA Futura Laboratory, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden
| | - Pol Figueras Ivern
- Division of Infectious Diseases, ANA Futura Laboratory, Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden
| | - Ákos Végvári
- Division of Chemistry I, Department of Medical Biochemistry and Biophysics, Karolinska Institutet, Stockholm, Sweden
| | - Anders Sönnerborg
- Division of Clinical Microbiology, ANA Futura Laboratory, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.,Division of Infectious Diseases, ANA Futura Laboratory, Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden.,Molecular Microbiology and Immunology, University of Missouri, Columbia, MO, United States
| | - Ujjwal Neogi
- Division of Clinical Microbiology, ANA Futura Laboratory, Department of Laboratory Medicine, Karolinska Institutet, Stockholm, Sweden.,Molecular Microbiology and Immunology, University of Missouri, Columbia, MO, United States
| | - Robert van Domselaar
- Division of Infectious Diseases, ANA Futura Laboratory, Department of Medicine Huddinge, Karolinska Institutet, Stockholm, Sweden
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