Lyndsay Kluge
Pronouns: she/her
Research Mentor(s): Yu Zuo
Co-Presenter:
Research Mentor School/College/Department: Internal Medicine / Medicine
Presentation Date: April 20
Presentation Type: Poster
Session: Session 6 – 4:40pm – 5:30 pm
Room: League Ballroom
Authors: Yu Zuo, Sherwin Navaz, Alex Tsodikov, Katarina Kmetova, Lyndsay Kluge, …, Jason Knight
Presenter: 92
Abstract
Background/Purpose: The release of neutrophil extracellular traps (NETs) by hyperactive neutrophils plays a role in the thromboinflammatory phenotype of APS. Previous work has demonstrated that some patients with APS have autoantibodies targeting NETs, which impair NET clearance and potentially activate complement. Here, we aimed to elucidate the presence, clinical associations, and antigen specificities of anti-NET antibodies in a large, ethnically diverse cohort of antiphospholipid antibody (aPL)-positive patients who did not have lupus. My role in this project is to elucidate the relationship between anti-NET antibodies and complement activation. Patients and Methods: Levels of anti-NET IgG/IgM were determined in sera of 308 patients with primary APS and 81 patients who were aPL positive but without “criteria†APS manifestations or another systemic autoimmune disease diagnosis. All patients were recruited as part of the APS ACTION consortium. A positive cut-off for anti-NET level was established at the 99th percentile optical density of healthy-control samples. Multivariate logistic regression with best variable model selection was used to determine clinical associations. For a subset of patients (n=214), we profiled autoantibodies with a microarray platform that included 120 potential autoantigens (66 associated with NETs based on literature mining). In order to elucidate the relationship between anti-NET antibodies and complements, we are currently performing enzyme-linked immunosorbent assays (ELISA’s) to quantify the levels of C3 and C4, which will then be visualized by immunofluorescence microscopy. Results: We found elevated levels of anti-NET IgG or IgM in 45% of aPL-positive patients, whether they met criteria for primary APS or not. There was a strong relationship between anti-NET IgG and anti-NET IgM (r=0.52, p<0.0001). High anti-NET antibody levels correlated with a circulating marker of NETs, myeloperoxidase (MPO)-DNA complexes (IgG r=0.12, p=0.02; IgM r=0.16, p=0.001). Anti-NET activity also demonstrated a positive correlation with levels of traditional aPL (anti-beta-2 glycoprotein I IgG: r=0.21, p<0.0001) and anticardiolipin IgG: r=0.19, p=0.0001). When considering clinical manifestations among aPL-positive patients, positive anti-NET IgG was strongly associated with brain white matter changes after adjusting for demographic variables and criteria aPL profiles (OR=11, 95% CI 1.9 to 62), but not with other aPL-related manifestations. By immunofluorescence microscopy, we determined that high anti-NET sera more efficiently deposited complement C3d on NETs. In pursuit of the antigen specificity of anti-NET antibodies, 214 samples were analyzed by autoantibody microarray. Anti-NET IgG positivity significantly associated with the following antigens: citrullinated-histone H1 and H4, MPO-DNA complexes, nucleosomes, centromere protein A (a histone H3 variant), heparan sulfate proteoglycan, laminin, and collagen VI. Meanwhile, anti-NET IgM positivity associated with the following: single-stranded DNA, double-stranded DNA, and proliferating cell nuclear antigen. Complement data is still being generated. Conclusion: In summary, these data reveal high levels of anti-NET antibodies in 45% of aPL-positive patients wherein they potentially activate the complement cascade and contribute to white matter changes. While anti-NET IgM may especially target DNA in NETs, anti-NET IgG appears more likely to target protein antigens. Presentation link
Biomedical Sciences, Natural/Life Sciences
