Defining the complement biomarker profile of C3 glomerulopathy

TY - JOUR

T1 - Defining the complement biomarker profile of C3 glomerulopathy

AU - Zhang, Yuzhou

AU - Nester, Carla M

AU - Martin, Bertha

AU - Skjoedt, Mikkel-Ole

AU - Meyer, Nicole C

AU - Shao, Dingwu

AU - Borsa, Nicolò

AU - Palarasah, Yaseelan

AU - Smith, Richard J H

N1 - Copyright © 2014 by the American Society of Nephrology.

PY - 2014

Y1 - 2014

N2 - Background and objectives C3 glomerulopathy (C3G) applies to a group of renal diseases defined by a specific renal biopsy finding: a dominant pattern of C3 fragment deposition on immunofluorescence. The primary pathogenic mechanism involves abnormal control of the alternative complement pathway, although a full description of the disease spectrum remains to be determined. This study sought to validate and define the association of complement dysregulation with C3G and to determine whether specific complement pathway abnormalities could inform disease definition. Design, setting, participants, & measurements This study included 34 patients with C3G (17 with C3 glomerulonephritis [C3GN] and 17 with dense deposit disease [DDD]) diagnosed between 2008 and 2013 selected from the C3G Registry. Control samples (n=100) were recruited from regional blood drives. Nineteen complement biomarkers were assayed on all samples. Results were compared between C3G disease categories and with normal controls. Results Assessment of the alternative complement pathway showed that compared with controls, patients with C3G had lower levels of serum C3 (P,0.001 for both DDD and C3GN) and factor B (P,0.001 for both DDD and C3GN) as well as higher levels of complement breakdown products including C3d (P,0.001 for both DDD and C3GN) and Bb (P,0.001 for both DDD and C3GN).A comparison of terminal complement pathway proteins showed that although C5 levels were significantly suppressed (P,0.001 for both DDD and C3GN) its breakdown product C5a was significantly higher only in patients with C3GN (P,0.05). Of the other terminal pathway components (C6–C9), the only significant difference was in C7 levels between patients with C3GN and controls (P,0.01). Soluble C5b-9 was elevated in both diseases but only the difference between patients with C3GN and controls reached statistical significance (P,0.001). Levels of C3 nephritic factor activity were qualitatively higher in patients with DDD compared with patients with C3GN. Conclusions Complement biomarkers are significantly abnormal in patients with C3G compared with controls. These data substantiate the link between complement dysregulation and C3G and identify C3G inter disease differences.

AB - Background and objectives C3 glomerulopathy (C3G) applies to a group of renal diseases defined by a specific renal biopsy finding: a dominant pattern of C3 fragment deposition on immunofluorescence. The primary pathogenic mechanism involves abnormal control of the alternative complement pathway, although a full description of the disease spectrum remains to be determined. This study sought to validate and define the association of complement dysregulation with C3G and to determine whether specific complement pathway abnormalities could inform disease definition. Design, setting, participants, & measurements This study included 34 patients with C3G (17 with C3 glomerulonephritis [C3GN] and 17 with dense deposit disease [DDD]) diagnosed between 2008 and 2013 selected from the C3G Registry. Control samples (n=100) were recruited from regional blood drives. Nineteen complement biomarkers were assayed on all samples. Results were compared between C3G disease categories and with normal controls. Results Assessment of the alternative complement pathway showed that compared with controls, patients with C3G had lower levels of serum C3 (P,0.001 for both DDD and C3GN) and factor B (P,0.001 for both DDD and C3GN) as well as higher levels of complement breakdown products including C3d (P,0.001 for both DDD and C3GN) and Bb (P,0.001 for both DDD and C3GN).A comparison of terminal complement pathway proteins showed that although C5 levels were significantly suppressed (P,0.001 for both DDD and C3GN) its breakdown product C5a was significantly higher only in patients with C3GN (P,0.05). Of the other terminal pathway components (C6–C9), the only significant difference was in C7 levels between patients with C3GN and controls (P,0.01). Soluble C5b-9 was elevated in both diseases but only the difference between patients with C3GN and controls reached statistical significance (P,0.001). Levels of C3 nephritic factor activity were qualitatively higher in patients with DDD compared with patients with C3GN. Conclusions Complement biomarkers are significantly abnormal in patients with C3G compared with controls. These data substantiate the link between complement dysregulation and C3G and identify C3G inter disease differences.

KW - Adolescent

KW - Adult

KW - Biomarkers

KW - Case-Control Studies

KW - Child

KW - Complement C3

KW - Complement C3 Nephritic Factor

KW - Complement C3d

KW - Complement C5

KW - Complement C5a

KW - Complement C7

KW - Complement Factor B

KW - Female

KW - Glomerulonephritis, Membranoproliferative

KW - Humans

KW - Male

KW - Middle Aged

KW - Young Adult

KW - Journal Article

KW - Research Support, Non-U.S. Gov't

U2 - 10.2215/cjn.01820214

DO - 10.2215/cjn.01820214

M3 - Journal article

C2 - 25341722

SN - 1555-9041

VL - 9

SP - 1876

EP - 1882

JO - Clinical Journal of American Society of Nephrology.

JF - Clinical Journal of American Society of Nephrology.

IS - 11

ER -