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Presentation Details
| Neutrophil-dependent interferonopathy promotes joint damage in hemophilia. Tomasz Kaminski1, Nicholas Swendrowski1, Margaret V.Ragni2, Lynn Malec1, 3, Prithu Sundd1, 4. 1Thrombosis and Hemostasis Program, Versiti Blood Research Institute, Milwaukee, WI, USA.2Department of Medicine, Division of Hematology, University of Pittsburgh, Pittsburgh, WI, USA.3Departments of Medicine and Pediatrics, Division of Hematology/Oncology, Medical College of Wisconsin, Milwaukee, WI, USA.4Department of Medicine (Hematology and Oncology), Medical College of Wisconsin, Milwaukee, WI, USA |
Abstract
Background Hemophilia-A is an X-linked congenital bleeding disorder, which is caused by the deficiency of coagulation FVIII. Recurrent joint bleeding (hemarthrosis) is the most frequent clinical manifestation of severe hemophilia A (FVIII<1%), which may progress to hemophilic arthropathy (HA), a debilitating condition marked by inflammation of the synovium, neo-angiogenesis and infiltration by neutrophils, eventually leading to joint-bone remodeling and permanent joint-damage. Recent evidence suggests that joint bleeding promotes the release of erythrocyte-derived damage-associated molecular pattern molecules (DAMPs) such as heme and hemoglobin that trigger sterile inflammation in the joints. However, the early events leading to the development of HA remain unclear. Objectives To identify early inflammatory events contributing to the development of HA. Methods Knee joints in FVIII-total knockout (F8TKO) or littermate WT male mice were injured using the model of single puncture-induced hemarthrosis. Scoring of the bleeding severity and histology of joints were conducted to assess the joint injury in mice. Imaging-flow-cytometry and ELISA assays were used to evaluate the number of circulating neutrophil extracellular traps (NETs) in the blood samples of patients diagnosed with/without HA and mice with/without knee injury. Neutrophils from HA patients, F8TKO mice and matched controls were isolated, activation of inflammatory caspases such caspase-1/4/5 (Human) and caspase-1/11 (Mouse)-dependent signaling was assessed in neutrophils using qRT-PCR (gene expression) and western blotting (protein levels and cleavage). ELISA was used to assess type-I interferon (IFN-α) production in neutrophils and how it promotes NETs generation. Results Unlike the control mice that completely recovered, F8TKO mice manifested unresolved joint injury and severe bleeding at 5-days post knee injury. Circulating fragments of NETs (cNETs) and NETs markers (neutrophil elastase and citrullinated histones H3) were significantly elevated in the plasma of hemophilia patients diagnosed with HA and injured F8TKO mice but not in plasma of control humans, injured WT mice or uninjured F8TKO mice. Type-I interferon signaling (IFN-I) is known to promote the expression of major inflammatory genes associated with NETs generation. Indeed, the levels of interferon-α were significantly elevated in neutrophils of injured F8TKO mice than injured WT mice. Next, western blotting analysis revealed the presence of cleaved (active) forms of Caspase-5 and Caspase-11 in neutrophils isolated from HA patients and F8TKO mice, respectively, but not in matched injured or uninjured controls. Principal genes (mRNA levels) associated with type-I IFN signaling and downstream caspase-5 or -11/gasdermin-D (GSDMD) mediated NETs generation were also significantly elevated in neutrophils of HA patients and injured F8TKO mice compared to matched injured or uninjured controls. Conclusions These findings are the first to suggest that IFN-I signaling leading to activation of caspase-5/11-dependent GSDMD activation in neutrophils promotes generation of NETs that contribute to the pathogenesis of early stages of HA. These findings also suggest that a local joint injury contributes to systemic inflammation (elevated circulating NETs) in severe hemophilia-A. Therefore, targeting IFN-I-caspase-5/11-NETs signaling can be a potential therapy to prevent progressive joint damage and associated systemic inflammation in hemophilia-A.
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No part of this publication may be reproduced, distributed, or transmitted in any form or by any means, including photocopying, recording, or other electronic or mechanical methods, without the prior written permission of the author.