PhD Scientific Days 2021

TT_II_L: Theoretical and Translational Medicine II. Lectures

Development of Immunoassays for Specific Classical and Lectin Pathway Activation Markers

Text of the abstract

Introduction: Infections and various immune-inflammatory conditions are characterized by complement activation, where antibodies initiate the classical pathway (CP) and repetitive carbohydrate structures (such as on the surface of bacteria or viruses) the lectin pathway (LP). There are several complement activation biomarkers currently on the market, but specific markers for early CP and LP activation are still missing. C1 inhibitor (C1INH), forming covalent bonds with active proteases like C1s (CP) or MASP-1 (LP), is a promising target for the development of such novel immunoassays.
Excessive complement activation was observed in COVID-19 and can lead to lung disease and severe patient outcome. Measurement of C1INH complexes might give an indication of how early complement activation occurs during an infection with the SARS-CoV-2 virus.
Aims: The aim of the project is the development of specific and sensitive immunoassays detecting C1INH complexes, indicating activation of the CP and LP of complement. Furthermore, the newly developed assays are used to investigate complement activation in patients suffering from COVID-19.
Methods: Assay development was performed at Hycult Biotech. After first prototypes were available, the newly developed assays were tested thoroughly using plasma samples from healthy and diseased individuals. Next, as part of a large validation study, these assays were used to investigate C1INH complexes in a large and well-characterized COVID-19 cohort comprising of 815 longitudinal samples from 315 individuals.
Results: Two well performing immunoassays were developed, which show low inter- and intra-assay variation and can measure C1s-C1INH and MASP1-C1INH complex concentrations in EDTA plasma from healthy and diseased individuals reliably. Furthermore, assessment of the C1INH complexes in COVID-19 patients showed that, for both complexes, levels were associated with disease severity (C1s-C1INH: p<0.05; MASP1-C1INH: p<0,0001).
Conclusion: The newly developed assays can be used for further studies investigating the role of C1INH complexes in several diseases or conditions affecting the CP and LP of complement. In addition, first preliminary results showed that changes in C1s-C1INH and MASP1-C1INH complex concentrations are associated with disease severity in COVID-19.
Funding: The project is funded by the EU MSCA project CORVOS 860044.

University and Doctoral School

Semmelweis University, Doctoral School of Theoretical and Translational Medicine