Abstract: TH-PO055

Detecting Autoreactive Cells and Pathogenic Epitopes in MPO-ANCA Vasculitis

Session Information

Category: Glomerular

  • 1001 Glomerular: Basic/Experimental Immunology and Inflammation

Authors

  • Stember, Katherine G., University of North Carolina Chapel Hill, Chapel Hill, North Carolina, United States
  • Hess, Jacob, UNC Kidney Center, Chapel Hill, North Carolina, United States
  • Henderson, Candace Dione, UNC Kidney Center, Chapel Hill, North Carolina, United States
  • Mallal, Simon, Vanderbilt University Medical Center, Nashville, Tennessee, United States
  • Jennette, J. Charles, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
  • Falk, Ronald J., University of North Carolina Hospitals, Chapel Hill, North Carolina, United States
  • Ciavatta, Dominic J., University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
  • Free, Meghan E., UNC Kidney Center, Chapel Hill, North Carolina, United States
Background

Anti-neutrophil cytoplasmic autoantibody (ANCA) vasculitis is an autoimmune disease that damages blood vessels throughout the body, and treatment regimens include immunosuppression. Previous studies demonstrated dysregulation of the adaptive immune system and identified two autoantigens: myeloperoxidase (MPO) and proteinase 3 (PR3). GWAS studies found an association between ANCA vasculitis and human leukocyte antigen (HLA). Mouse and human studies identified pathogenic MPO epitopes. Our lab sought to investigate MPO epitopes recognized by autoreactive B and T cells in patients.

Methods

We used an in-house ELISA to test antibody reactivity to a previously identified linear MPO epitope. We HLA sequenced 203 patients to identify disease-associated alleles and used predictive and in vitro binding studies to assess MHC-peptide binding. MHC II tetramers were produced for DPB1*04:01 and DRB4*01:01 containing MPO epitopes and controls. Patient PBMCs were incubated with tetramers, stained with surface markers, and analyzed by flow cytometry day 1 ex vivo.

Results

Our ELISA revealed 53% percent of patients have autoantibodies that bind MPO447-461, most often at disease onset. Patients carrying HLA of interest demonstrate specific CD4+ T cell recognition of tetramers containing MPO epitopes. The majority of tetramer positive cells are CD25intermediate cells, and are positive for CD45RO and CCR7 memory markers. Additionally they secrete IL-17 when stimulated.

Conclusion

Recently, it was shown that MPO409-428 induced tolerance and attenuated disease in a mouse model of anti-MPO GN. Patient CD4+ T cells show significant reactivity to tetramers carrying the human homolog of this epitope. Ideally, we will use this region of MPO to inform the development of new therapies for patients with ANCA vasculitis.

Funding

  • NIDDK Support