Osteopontin in antineutrophil cytoplasmic autoantibody-associated vasculitis: relation to disease activity, organ manifestation and immunosuppressive therapy.
BACKGROUND
Osteopontin is a pleiotropic cytokine involved in the recruitment and retention of neutrophils to sites of inflammation, which are the primary targets cells in antineutrophil cytoplasmic autoantibody-associated vasculitis (AAV). Osteopontin may play a role in the pathogenesis of AAV.


METHODS
24 patients with systemic AAV and six patients with limited granulomatous disease were included. 19 patients were followed up at 6 and 12 months after the initiation of immunosuppressive therapy. 21 matched healthy volunteers and 20 body mass index and glomerular filtration rate-matched patients with IgA nephropathy were included as controls. Plasma levels of osteopontin were measured by ELISA. Disease activity was gauged by the Birmingham vasculitis activity score (BVAS) and C-reactive protein (CRP).


RESULTS
Osteopontin levels are elevated compared with controls (healthy p<0.001; IgA p<0.001).Osteopontin levels decrease significantly during follow-up (p=0.02). Osteopontin levels correlate with disease activity (BVAS r=0.93; CRP r=0.73; all p<0.001) as well as erythrocyturia (r=0.7, p<0.001) and proteinuria (r=0.54, p=0.007).


CONCLUSIONS
Active AAV is characterised by increased plasma levels of osteopontin, which decrease dramatically with successful therapy. Osteopontin may mediate the inflammatory process in AAV through the recruitment of neutrophils.
Lorenzen
Johan
J
Hannover Medical School, Department of Internal Medicine, Division of Nephrology, 30625 Hannover, Germany. j.m.lorenzen@gmail.com
Lovric
Svjetlana
S
Krämer
Robert
R
Haller
Hermann
H
Haubitz
Marion
M
D000328:Adult; D000368:Aged; D056648:Anti-Neutrophil Cytoplasmic Antibody-Associated Vasculitis / Q000097:blood* / Q000188:drug therapy; D019268:Antibodies, Antineutrophil Cytoplasmic / Q000097:blood*; D015415:Biomarkers / Q000097:blood; D015992:Body Mass Index; D002097:C-Reactive Protein / Q000378:metabolism; D005260:Female; D005500:Follow-Up Studies; D005919:Glomerular Filtration Rate; D006801:Humans; D007166:Immunosuppressive Agents / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D053495:Osteopontin / Q000097:blood*; D012720:Severity of Illness Index
D019268:Antibodies, Antineutrophil Cytoplasmic; D015415:Biomarkers; D007166:Immunosuppressive Agents; D053495:Osteopontin; D002097:C-Reactive Protein