Kidney Week

Abstract: FR-PO831

Hydralazine-Associated Anti-neutrophilic Cytoplasmic Antibody (ANCA)-Associated Vasculitis: A Model of Drug-Associated Autoimmunity

Session Information

• Glomerular Diseases: Inflammation and Immunology
  October 25, 2024 | Location: Exhibit Hall, Convention Center
  Abstract Time: 10:00 AM - 12:00 PM

Category: Glomerular Diseases

• 1401 Glomerular Diseases: Mechanisms, including Podocyte Biology

Authors

• Xi, Gang, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Gang Xi, PhD

• Lardinois, Olivier, Mass Spectrometry Research and Support Group, National Institute of Environmental Health Sciences, NIH, Research Triangle Park, North Carolina, United States

Olivier Lardinois, PhD

• Hu, Peiqi, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Peiqi Hu, MD

• McInnis, Elizabeth A., The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Elizabeth A. McInnis

• Poulton, John S., The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

John S. Poulton, PhD

• Free, Meghan E., The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Meghan E. Free, PhD

• Chen, Dhruti P., The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Dhruti P. Chen, MD

• Zeitler, Evan, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Evan Zeitler, MD, FASN

• Wu, Eve, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Eve Wu, MD

• Derebail, Vimal K., The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Vimal K. Derebail, MD, MPH, FASN

• Jennette, J. Charles, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

J. Charles Jennette, MD

• Falk, Ronald, The University of North Carolina at Chapel Hill Kidney Center, Chapel Hill, North Carolina, United States

Ronald Falk, MD, FASN

Background

Drug-associated autoimmunity is a recognized phenomenon, but underlying mechanisms are not completely elucidated. We previously demonstrated that hydralazine adduct formation on myeloperoxidase (MPO) resulted in production of anti-hydrazone MPO antibodies, which contributed to development of hydralazine associated ANCA vasculitis. Here, we examine additional disease-associated drugs in vitro and further explored the in vivo effects of modified MPO using mouse models.

Methods

Aminoguanidine (AG)- or propylthiouracil (PTU)-modified myoglobin (Mb) were analyzed with reverse phase HPLC and electrospray mass spectrometry. Levamisole- or AG-modified MPO were used to investigate the mechanism by which drugs could modify MPO. Unmodified and modified mouse recombinant MPO (rmMPO) were injected into wild type C57BL/6 mouse or MPO null mice. Mouse T cells were isolated for ELISpot assays 4 weeks after immunization. Splenocytes from immunized mice were isolated and injected into Rag2 ^-/- mice to study the pathogenic activity of modified MPO. After 2 weeks, mice were sacrificed. Serum IgG and IgM were measured with ELISA and kidneys were collected for histology.

Results

Mass spectrometry data showed that, like hydralazine, the amine group of AG bound to a carbonyl group of Mb. PTU bound to Mb via sulfenic/sulfinic/sulfonic derivatives to generate a PTU adduct. AG was able to competitively block hydrazone adduct formation on MPO. Levamisole, like PTU, bound to MPO with sulfenic derivatives and was unable to prevent hydrazone formation on MPO. ELISpot data revealed that hydralazine-modified rmMPO only stimulated IL-17a production while unmodified rmMPO stimulated both IFNγ and IL-17a production. Anti-rmMPO or anti-hydralazine modified MPO IgG were detected, but IgM was undetectable in both settings. Splenocytes from MPO^-/- mice immunized with hydralazine modified rmMPO caused glomerulonephritis when injected into Rag2^-/- mice.

Conclusion

Our current study suggest that different drugs may bind to MPO via different mechanisms but can still induce ANCA by similarly forming an adduct on MPO. Animal models clearly demonstrate hydralazine-modified MPO stimulates T-cell activation and pathogenic IgG that induces ANCA glomerulonephritis in mice.

Funding

• NIDDK Support