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 TMAin 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 78months (interquartile range, 18-135months); 18 patients reached ESRD(10 of 14 and 8 of 26 in the lowand 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 patientswho 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.

Association of serum C3 concentration and histologic signs of thrombotic microangiopathy with outcomes among patients with ANCA-associated renal vasculitis / Manenti, Lucio; Vaglio, Augusto; Gnappi, Elisa; Maggiore, Umberto; Allegri, Landino; Allinovi, Marco; Urban, Maria L.; Delsante, Marco; Galetti, Maricla; Nicastro, Maria; Pilato, Francesco P.; Buzio, Carlo. - In: CLINICAL JOURNAL OF THE AMERICAN SOCIETY OF NEPHROLOGY. - ISSN 1555-9041. - 10:12(2015), pp. 2143-2151. [10.2215/CJN.00120115]

Association of serum C3 concentration and histologic signs of thrombotic microangiopathy with outcomes among patients with ANCA-associated renal vasculitis

MANENTI, Lucio;VAGLIO, Augusto;GNAPPI, Elisa;MAGGIORE, UMBERTO;ALLEGRI, Landino;URBAN, Maria Letizia;DELSANTE, Marco;GALETTI, Maricla;BUZIO, Carlo
2015

Abstract

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 TMAin 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 78months (interquartile range, 18-135months); 18 patients reached ESRD(10 of 14 and 8 of 26 in the lowand 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 patientswho 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.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11381/2828302
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