Functional evaluation of complement factor I variants by immunoassays and SDS-PAGE

Copyright © 2023 Gerogianni, Baas, Sjöström, van de Kar, Pullen, van de Peppel, Nilsson and van den Heuvel..

Factor I (FI) is an essential regulator of the complement system. Together with co-factors, FI degrades C3b, which inhibits further complement activation. Genetic mutations in FI are associated with pathological conditions like age-related macular degeneration and atypical hemolytic uremic syndome. Here, we evaluated eight recombinant FI genetic variants found in patients. We assessed FI's co-factor activity in the presence of two co-factors; Factor H and soluble CR1. Different analytical assays were employed; SDS-PAGE to evaluate the degradation of C3b, ELISA to measure the generation of fluid phase iC3b and the degradation of surface-bound C3b using a novel Luminex bead-based assay. We demonstrate that mutations in the FIMAC and SP domains of FI led to significantly reduced protease activity, whereas the two analyzed mutations in the LDLRA2 domain did not result in any profound changes in FI's function. The different assays employed displayed a strong positive correlation, but differences in the activity of the genetic variants Ile55Phe and Gly261Asp could only be observed by combining different methods and co-factors for evaluating FI activity. In conclusion, our results provide a new perspective regarding available diagnostic tools for assessing the impact of mutations in FI.

Medienart:

E-Artikel

Erscheinungsjahr:

2023

Erschienen:

2023

Enthalten in:

Zur Gesamtaufnahme - volume:14

Enthalten in:

Frontiers in immunology - 14(2023) vom: 06., Seite 1279612

Sprache:

Englisch

Beteiligte Personen:

Gerogianni, Alexandra [VerfasserIn]
Baas, Laura M [VerfasserIn]
Sjöström, Dick J [VerfasserIn]
van de Kar, Nicole C A J [VerfasserIn]
Pullen, Marit [VerfasserIn]
van de Peppel, Siem J [VerfasserIn]
Nilsson, Per H [VerfasserIn]
van den Heuvel, Lambertus P [VerfasserIn]

Links:

Volltext

Themen:

80295-43-8
Co-factor activity
Complement C3b
Complement Factor I
Complement receptor I
Complement regulation
EC 3.4.21.45
Factor H
Factor I
Functional assay
Journal Article
Research Support, Non-U.S. Gov't

Anmerkungen:

Date Completed 14.11.2023

Date Revised 22.11.2023

published: Electronic-eCollection

Citation Status MEDLINE

doi:

10.3389/fimmu.2023.1279612

funding:

Förderinstitution / Projekttitel:

PPN (Katalog-ID):

NLM364462361