Session Information
Session Type: Abstract Session
Session Time: 8:00AM-9:00AM
Background/Purpose: Lyn kinase is a member of the Src family of tyrosine kinases that regulates innate and adaptive immune responses. Lyn C-terminal tail tyrosine residue, p.Y508, inactivates wildtype Lyn kinase upon phosphorylation. We describe 3 unrelated patients with de novo LYN mutations affecting p.Y508, whose disease sheds light on the pathogenesis of neutrophilic small vessel vasculitis.
Methods: All patients (Pts) were enrolled into an IRB-approved natural history protocol (NCT02974595). The effects of the LYN mutations were investigated in Pts’ and healthy control (HC) blood cells and serum, in transfection and immunological studies and in induced pluripotent stem cells (iPS cells)-derived endothelial cells (iECs).
Results: The three Pts presented with perinatal purpuric rash and systemic inflammation, hepatosplenomegaly, periorbital erythema, abdominal and testicular pain. Pts 1 and 3 had early onset liver fibrosis. Transiently elevated autoantibodies (ANA, anti-Sm, anti-SSA) were present in Pt 1. All patients had a skin biopsy showing neutrophilic small vessel vasculitis. The 3 Pts were found to have de novo mutations in LYN: p.Y508* in Pt 1, p.Y508F in Pt 2 and p.Q507* in Pt 3 and responded partially (Pts 1 and 3) or fully (Pt 2) to the TNF inhibitor etanercept. Combination therapy with the Src kinase inhibitor, dasatinib, led to resolution of liver fibrosis in Pt 1. Transfection of wildtype and mutant Lyn into HEK293FT cells showed constitutive phosphorylation of the activating tyrosine, p.Y397, and absent phosphorylation of the inhibitory tyrosine, p.Y508. Skin biopsies showed a dense neutrophilic infiltrate with small vessel wall destruction and neutrophil extracellular traps (NETs) formation; ICAM-1 was upregulated and focally colocalized with the EC marker CD31. All Pts showed elevated pro-inflammatory cytokines, and/or markers of neutrophil (L-selectin) and EC activation (ICAM-1, E-selectin) in serum. Monocyte-derived macrophages released increased levels of TNF-a, IL-6, CXCL10 and sICAM-1 upon LPS stimulation. Neutrophils from Pt 1 showed signs of constitutive activation, including high surface expression of b2-integrins. Expression of ICAM-1 in areas of adherent neutrophils were increased in Pt 1 iEC/HC neutrophil co-cultures compared to isogenic and HC iEC. Neutrophil adhesion and ICAM-1 clusters were blocked with dasatinib and less with the TNF inhibitor. Transendothelial migration of HC neutrophils through Pt 1 iECs was increased compared to isogenic or HC iECs and reduced by treatment with dasatinib or TNF inhibitor.
Conclusion: We describe a novel autoinflammatory disease which we called Lyn associated vasculopathy and liver fibrosis (LAVLI). De novo activating LYN mutations link Lyn kinase to regulating dermal vascular permeability, restricting inflammatory signals in immune cells, and promoting hepatic fibrosis. Functional data support a stepwise approach to treatment of reserving dasatinib for patients with liver fibrosis and insufficient responses to TNF inhibition. This study identifies Lyn kinase as potential treatment target in neutrophilic small vessel vasculitis and early liver fibrosis.
This study was supported in part by the IRP of NIAID, NIH.
To cite this abstract in AMA style:
Almeida de Jesus A, Chen G, Yang D, Brdicka T, Ruth N, Bennin D, Cebecauerova D, Malcova H, Freeman H, Martin N, Svojgr K, Passo M, Bhuyan F, Alehashemi S, Rastegar A, Uss K, Kardova L, Duric I, Omoyinmi E, Peldova P, Lee C, Kleiner D, Hadigan C, Hewitt S, Pittaluga S, Carmona-Rivera C, Calvo K, Shah N, Balascakova M, Fink D, Kotalova R, Parackova Z, Peterkova L, Kuzilkova D, Campr V, Sramkova L, Brooks S, Meffre E, Harper R, Kuehn H, Kaplan M, Brogan P, Rosenzweig S, Deng Z, Huttenlocher A, Moir S, Kuhns D, Boehm M, Skvarova Kramarzova K, Goldbach-Mansky R. Gain-of-Function Mutations in Lyn Kinase Cause a Novel Autoinflammatory Disease with Small Vessel Vasculitis and Liver Fibrosis [abstract]. Arthritis Rheumatol. 2022; 74 (suppl 9). https://acrabstracts.org/abstract/gain-of-function-mutations-in-lyn-kinase-cause-a-novel-autoinflammatory-disease-with-small-vessel-vasculitis-and-liver-fibrosis/. Accessed .« Back to ACR Convergence 2022
ACR Meeting Abstracts - https://acrabstracts.org/abstract/gain-of-function-mutations-in-lyn-kinase-cause-a-novel-autoinflammatory-disease-with-small-vessel-vasculitis-and-liver-fibrosis/