PMID- 36428281 OWN - NLM STAT- MEDLINE DCOM- 20221229 LR - 20230415 IS - 2326-5205 (Electronic) IS - 2326-5191 (Print) IS - 2326-5191 (Linking) VI - 75 IP - 1 DP - 2023 Jan TI - Syk Activation in Circulating and Tissue Innate Immune Cells in Antineutrophil Cytoplasmic Antibody-Associated Vasculitis. PG - 84-97 LID - 10.1002/art.42321 [doi] AB - OBJECTIVE: Syk is a cytoplasmic protein tyrosine kinase that plays a role in signaling via B cell and Fc receptors (FcR). FcR engagement and signaling via Syk is thought to be important in antineutrophil cytoplasm antibody (ANCA) IgG-mediated neutrophil activation. This study was undertaken to investigate the role of Syk in ANCA-induced myeloid cell activation and vasculitis pathogenesis. METHODS: Phosphorylation of Syk in myeloid cells from healthy controls and ANCA-associated vasculitis (AAV) patients was analyzed using flow cytometry. The effect of Syk inhibition on myeloperoxidase (MPO)-ANCA IgG activation of cells was investigated using functional assays (interleukin-8 and reactive oxygen species production) and targeted gene analysis with NanoString. Total and phosphorylated Syk at sites of tissue inflammation in patients with AAV was assessed using immunohistochemistry and RNAscope in situ hybridization. RESULTS: We identified increased phosphorylated Syk at critical activatory tyrosine residues in blood neutrophils and monocytes from patients with active AAV compared to patients with disease in remission or healthy controls. Syk was phosphorylated in vitro following MPO-ANCA IgG stimulation, and Syk inhibition was able to prevent ANCA-mediated cellular responses. Using targeted gene expression analysis, we identified up-regulation of FcR- and Syk-dependent signaling pathways following MPO-ANCA IgG stimulation. Finally, we showed that Syk is expressed and phosphorylated in tissue leukocytes at sites of organ inflammation in AAV. CONCLUSION: These findings indicate that Syk plays a critical role in MPO-ANCA IgG-induced myeloid cell responses and that Syk is activated in circulating immune cells and tissue immune cells in AAV; therefore, Syk inhibition may be a potential therapeutic option. CI - (c) 2022 The Authors. Arthritis & Rheumatology published by Wiley Periodicals LLC on behalf of American College of Rheumatology. FAU - Prendecki, Maria AU - Prendecki M AUID- ORCID: 0000-0001-7048-7457 AD - Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, and Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK. FAU - Gulati, Kavita AU - Gulati K AUID- ORCID: 0000-0002-2651-593X AD - Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, and Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK. FAU - Pisacano, Noelle AU - Pisacano N AD - National Heart and Lung Institute, Imperial College, London, UK. FAU - Pinheiro, Damilola AU - Pinheiro D AD - Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, London, UK. FAU - Bhatt, Tejal AU - Bhatt T AD - Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, London, UK. FAU - Mawhin, Marie-Anne AU - Mawhin MA AD - Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, London, UK. FAU - Toulza, Frederic AU - Toulza F AD - Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, London, UK. FAU - Masuda, Esteban S AU - Masuda ES AD - Rigel Pharmaceuticals, South San Francisco, California. FAU - Cowburn, Andrew AU - Cowburn A AD - National Heart and Lung Institute, Imperial College, London, UK. FAU - Lodge, Katharine M AU - Lodge KM AD - National Heart and Lung Institute, Imperial College, London, UK. FAU - Tam, Frederick W K AU - Tam FWK AD - Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, and Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK. FAU - Roufosse, Candice AU - Roufosse C AD - Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, London, UK. FAU - Pusey, Charles D AU - Pusey CD AD - Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, and Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK. FAU - McAdoo, Stephen P AU - McAdoo SP AUID- ORCID: 0000-0001-8260-8770 AD - Department of Immunology and Inflammation, Centre for Inflammatory Disease, Imperial College London, Hammersmith Campus, and Imperial College Renal and Transplant Centre, Imperial College Healthcare NHS Trust, Hammersmith Hospital, London, UK. LA - eng PT - Journal Article PT - Research Support, Non-U.S. Gov't DEP - 20221125 PL - United States TA - Arthritis Rheumatol JT - Arthritis & rheumatology (Hoboken, N.J.) JID - 101623795 RN - 0 (Antibodies, Antineutrophil Cytoplasmic) RN - 0 (Receptors, Fc) RN - 0 (Immunoglobulin G) RN - EC 1.11.1.7 (Peroxidase) RN - EC 2.7.10.2 (SYK protein, human) RN - EC 2.7.10.2 (Syk Kinase) SB - IM MH - Humans MH - *Antibodies, Antineutrophil Cytoplasmic MH - *Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis MH - Inflammation MH - Receptors, Fc MH - Immunoglobulin G MH - Immunity, Innate MH - Peroxidase MH - Syk Kinase PMC - PMC10099805 EDAT- 2022/11/27 06:00 MHDA- 2022/12/30 06:00 PMCR- 2023/04/13 CRDT- 2022/11/26 00:33 PHST- 2022/06/21 00:00 [revised] PHST- 2021/11/23 00:00 [received] PHST- 2022/07/26 00:00 [accepted] PHST- 2022/11/27 06:00 [pubmed] PHST- 2022/12/30 06:00 [medline] PHST- 2022/11/26 00:33 [entrez] PHST- 2023/04/13 00:00 [pmc-release] AID - ART42321 [pii] AID - 10.1002/art.42321 [doi] PST - ppublish SO - Arthritis Rheumatol. 2023 Jan;75(1):84-97. doi: 10.1002/art.42321. Epub 2022 Nov 25.