Original Research ARTICLE
S-nitrosylation of α1-antitrypsin triggers macrophages towards inflammatory phenotype and enhances intra-cellular bacteria elimination
- 1Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Israel
- 2Department of Biochemistry, The Ruth and Bruce Rappaport Faculty of Medicine, Technion Israel Institute of Technology, Israel
- 3Division of Pediatrics, Soroka Medical Center, Israel
- 4Department of Microbiology and Immunology, University of British Columbia, Canada
Background. Human α1-antitrypsin (hAAT) is a circulating anti-inflammatory serine-protease inhibitor that rises during acute phase responses. In vivo, hAAT reduces bacterial load, without directly inhibiting bacterial growth. In conditions of excess nitric-oxide (NO), hAAT undergoes S-nitrosylation (S-NO-hAAT) and gains antibacterial capacity. The impact of S-NO-hAAT on immune cells has yet to be explored.
Aim. Study the effects of S-NO-hAAT on immune cells during bacterial infection. Methods. Clinical-grade hAAT was S-nitrosylated and then compared to unmodified hAAT, functionally and structurally. Intracellular bacterial clearance by THP-1 macrophages was assessed using live Salmonella typhi. Murine peritoneal macrophages were examined, and signaling pathways were evaluated. S-NO-hAAT was also investigated after blocking free mambranal cysteine residues on cells.
Results. S-NO-hAAT (27.5 uM) enhances intracellular bacteria elimination by immunocytes (up to 1-log reduction). S-NO-hAAT causes resting macrophages to exhibit a pro-inflammatory and antibacterial phenotype, including release of inflammatory cytokines and induction of iNOS and TLR2. These pro-inflammatory effects are dependent upon cell surface thiols and activation of MAPK pathways.
Conclusions. hAAT duality appears to be context-specific, involving S-nitrosylation in a nitric oxide rich environment. Our results suggest that S-nitrosylation facilitates the antibacterial activity of hAAT by promoting its ability to activate innate immune cells. This pro-inflammatory effect may involve transferring of nitric oxide from S-NO-hAAT to a free cysteine residue on cellular targets.
Keywords: Cell activation, Cytokines, Infection, Inflammation, Nitric oxide - NO, Protease, Acute phase response proteins
Received: 12 Nov 2018;
Accepted: 05 Mar 2019.
Edited by:Juarez Antonio S. Quaresma, Instituto Evandro Chagas, Brazil
Reviewed by:Christian U. Riedel, University of Ulm, Germany
Victor C. Castro-Alves, University of São Paulo, Brazil
Matthew Brook, University of Edinburgh, United Kingdom
Copyright: © 2019 Kaner, Rotem, Schuster, Rider, Greenberg, Av-Gay, Benhar and Lewis. This is an open-access article distributed under the terms of the Creative Commons Attribution License (CC BY). The use, distribution or reproduction in other forums is permitted, provided the original author(s) and the copyright owner(s) are credited and that the original publication in this journal is cited, in accordance with accepted academic practice. No use, distribution or reproduction is permitted which does not comply with these terms.
Dr. Ziv Kaner, Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel, email@example.com
Prof. Eli C. Lewis, Department of Clinical Biochemistry and Pharmacology, Faculty of Health Sciences, Ben-Gurion University of the Negev, Beer Sheva, Israel, firstname.lastname@example.org