BACKGROUND AND OBJECTIVES: Complement alternative pathway (cAP) activation has recently been recognized as a key pathogenic event in ANCA-associated vasculitis (AAV). cAP dysregulation is also a major determinant of thrombotic microangiopathies (TMA), which can in turn complicate AAV. We explored the prognostic significance of cAP activation and of histologic evidence of TMA in a cohort of patients with renal AAV. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We studied 46 patients with AAV diagnosed between January 1990 and December 2011 at the Nephrology Unit of Parma University Hospital; 30 of them had undergone renal biopsy. We analyzed serum levels of C3 (sC3) and C4 (sC4) and, for 19 patients who had frozen plasma, plasma Bb and C5b-9 levels. We also reviewed all kidney biopsy specimens, specifically searching for histologic signs of TMA, and performed immunofluorescence or immunohistochemistry for C3d, C4d, Bb and C5b-9. RESULTS: sC3 was below the lower limit of normal in 35% of the patients, whereas C4 was low in only 2%. Patients with low sC3 tended to be older (P=0.04) and to have lower eGFR at diagnosis (P=0.06). The median follow-up was 78 months (interquartile range, 18-135 months); 18 patients reached ESRD (10 of 14 and 8 of 26 in the low and normal sC3 groups, respectively). Death-censored renal survival was lower in the low sC3 group than in the normal sC3 group (log-rank test, P=0.01). Eight of the 30 patients who had undergone biopsy (27%) had histologic signs of TMA; these signs were more frequent in patients with low sC3 (5 of 10 versus 3 of 20; P=0.04). Notably, patients with histologic signs of TMA had a dramatically worse death-censored renal survival than patients without TMA (log-rank test, P=0.01), with ESRD occurring in 8 of 8 patients with TMA versus 8 of 22 patients without TMA. CONCLUSIONS: Low sC3 levels and histologic signs of TMA are associated with a poor renal prognosis in patients with AAV.
BACKGROUND AND OBJECTIVES: Complement alternative pathway (cAP) activation has recently been recognized as a key pathogenic event in ANCA-associated vasculitis (AAV). cAP dysregulation is also a major determinant of thrombotic microangiopathies (TMA), which can in turn complicate AAV. We explored the prognostic significance of cAP activation and of histologic evidence of TMA in a cohort of patients with renal AAV. DESIGN, SETTING, PARTICIPANTS, & MEASUREMENTS: We studied 46 patients with AAV diagnosed between January 1990 and December 2011 at the Nephrology Unit of Parma University Hospital; 30 of them had undergone renal biopsy. We analyzed serum levels of C3 (sC3) and C4 (sC4) and, for 19 patients who had frozen plasma, plasma Bb and C5b-9 levels. We also reviewed all kidney biopsy specimens, specifically searching for histologic signs of TMA, and performed immunofluorescence or immunohistochemistry for C3d, C4d, Bb and C5b-9. RESULTS: sC3 was below the lower limit of normal in 35% of the patients, whereas C4 was low in only 2%. Patients with low sC3 tended to be older (P=0.04) and to have lower eGFR at diagnosis (P=0.06). The median follow-up was 78 months (interquartile range, 18-135 months); 18 patients reached ESRD (10 of 14 and 8 of 26 in the low and normal sC3 groups, respectively). Death-censored renal survival was lower in the low sC3 group than in the normal sC3 group (log-rank test, P=0.01). Eight of the 30 patients who had undergone biopsy (27%) had histologic signs of TMA; these signs were more frequent in patients with low sC3 (5 of 10 versus 3 of 20; P=0.04). Notably, patients with histologic signs of TMA had a dramatically worse death-censored renal survival than patients without TMA (log-rank test, P=0.01), with ESRD occurring in 8 of 8 patients with TMA versus 8 of 22 patients without TMA. CONCLUSIONS: Low sC3 levels and histologic signs of TMA are associated with a poor renal prognosis in patients with AAV.
Authors: Andrew S Levey; Josef Coresh; Tom Greene; Jane Marsh; Lesley A Stevens; John W Kusek; Frederick Van Lente Journal: Clin Chem Date: 2007-03-01 Impact factor: 8.327
Authors: Hong Xiao; Daniel J Dairaghi; Jay P Powers; Linda S Ertl; Trageen Baumgart; Yu Wang; Lisa C Seitz; Mark E T Penfold; Lin Gan; Peiqi Hu; Bao Lu; Norma P Gerard; Craig Gerard; Thomas J Schall; Juan C Jaen; Ronald J Falk; J Charles Jennette Journal: J Am Soc Nephrol Date: 2013-10-31 Impact factor: 10.121
Authors: D Huugen; A van Esch; H Xiao; C J Peutz-Kootstra; W A Buurman; J W Cohen Tervaert; J C Jennette; P Heeringa Journal: Kidney Int Date: 2007-02-14 Impact factor: 10.612
Authors: Danielle Cohen; Marije Koopmans; Idske C L Kremer Hovinga; Stefan P Berger; Marian Roos van Groningen; Gerda M Steup-Beekman; Emile de Heer; Jan Anthonie Bruijn; Ingeborg M Bajema Journal: Arthritis Rheum Date: 2008-08