Acquired and genetic drivers of C3 and C5 convertase dysregulation in C3 glomerulopathy and immunoglobulin-associated MPGN.

Dysregulation of the alternative pathway of complement plays a central role in the pathophysiology of C3 Glomerulopathy (C3G). Various autoimmune and genetic factors targeting the alternative pathway have been associated to both C3G and primary Immunoglobulin-associated Membranoproliferative Glomerulonephritis (Ig-MPGN), suggesting shared pathophysiological mechanisms. This review highlights the wide range of disease drivers identified that mainly target components or protein complexes of the alternative pathway, both in C3G and Ig-MPGN.

Acquired and genetic determinants of disease phenotype and therapeutic strategies in C3 glomerulopathy and immunoglobulin-associated MPGN.

C3 glomerulopathy (C3G), a prototype of complement mediated disease, is characterized by significant heterogeneity, not only in terms of clinical, histological and biological presentation but also of prognosis, and response to existing therapies. Recent advancements in understanding the factors responsible for alternative pathway dysregulation in the disease have highlighted its even more complex nature. Here, we propose a reexamination of the diversity of C3G presentations in light of the drivers of complement activation.

Complement Terminal Pathway Activation and Intrarenal Immune Response in C3 Glomerulopathy.

Key Points: We evidenced terminal pathway activation (C5b-9 deposits) in most of the glomeruli on kidney biopsy of C3 glomerulopathy. The amount of C5b-9 deposits correlated with disease prognosis in C3 glomerulopathy. Increased terminal pathway activation was found predominantly in a subgroup exhibiting an immuno-fibroblastic signature.

Usefulness and analytical performances of complement multiplex assay for measuring complement biomarkers in plasma.

Introduction: The complement system is involved in numerous diseases, through diverse mechanisms and degree of activation. With the emergence of complement targeting therapeutic, simple and accessible tools to evaluate the extent of complement activation are strongly needed.

Methods: We evaluated two multiplex panels, measuring complement activation fragments (C4a, C3a, C5a, Bb, Ba, sC5b9) and intact components or regulators (C1q, C2, C3, C4, C5, FD, FP, FH, FI).