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Cluster Analysis Identifies Distinct Pathogenetic Patterns in C3 Glomerulopathies/Immune Complex-Mediated
Paraskevas Iatropoulos1, Erica Daina2, Manuela Curreri1
1IRCCS-Istituto di Ricerche Farmacologiche Mario Negri, Clinical Research Center for Rare Diseases Aldo e Cele Daccò, Ranica Bergamo, Italy.
Journal of the American Society of Nephrology : JASN
|October 15, 2017
Summary
This study reclassifies Membranoproliferative GN (MPGN) into four distinct patterns based on complement activation. Identifying these patterns aids in understanding C3 glomerulopathy (C3G) and immune complex-MPGN (IC-MPGN) etiology and improving patient risk assessment.
Area of Science:
- Nephrology
- Immunology
- Complement System Biology
Background:
- Membranoproliferative GN (MPGN) classification evolved to C3 glomerulopathy (C3G) and immune complex-MPGN (IC-MPGN).
- Alternative pathway complement abnormalities are implicated in both C3G and IC-MPGN.
- Distinct pathophysiologic mechanisms within MPGN subtypes require further elucidation.
Purpose of the Study:
- To identify distinct disease entities within C3G/IC-MPGN based on underlying pathophysiologic mechanisms.
- To stratify patients into clusters reflecting specific complement activation patterns.
- To develop an algorithm for patient classification and potential risk stratification.
Main Methods:
- Unsupervised hierarchical clustering of histologic, genetic, clinical, and serum/plasma complement data.
- Analysis of 173 patients diagnosed with C3G/IC-MPGN.
- Development of a classification algorithm for patient assignment.
Main Results:
- Four distinct patient clusters emerged, representing different pathogenetic patterns of complement activation.
- Clusters 1-3 showed fluid-phase complement activation with low C3 and high alternative pathway abnormalities.
- Cluster 4 demonstrated solid-phase complement activation with normal/mildly altered C3, late onset, and poor renal survival.
- Specific clusters were associated with alternative/terminal pathway activation, classic pathway involvement, or C3 convertase activation and distinct deposit types.
Conclusions:
- The findings support the existence of four distinct pathogenetic patterns within C3G/IC-MPGN.
- Patient stratification based on complement activation mechanisms can clarify disease etiology.
- This classification may improve risk assessment for end-stage renal disease (ESRD) and guide personalized treatment strategies.