PB0779 - NETs and terminal complement pathway as potential biomarkers for complement overactivation assessment in ANCA-associated vasculitis

Monday, June 26, 2023

18:30 – 19:30 ET

Room: Exhibition

Presenting Author(s)

MP

Marta Palomo

PhD
Hematology External Quality Assessment Laboratory, Biomedical Diagnostic Center, Hospital Clinic of Barcelona, Barcelona, Spain.
Barcelona, Catalonia, Spain

Co-Author(s)

EG

Elena Guillen

Doctor
Nephrology Unit, Hospital Clinic, Barcelona, Spain.
Barcelona, Catalonia, Spain
AR

Alex Ramos

Predoctoral Student
Josep Carreras Leukaemia Research Institute (Campus Clinic). Barcelona
Barcelona, Catalonia, Spain
Julia Martinez-Sanchez, PhD

PhD student
Hemostasis and Erythropathology Laboratory, Hematopathology, Department of Pathology, Hospital Clínic de Barcelona, Universitat de Barcelona, Barcelona, Spain.
Barcelona, Catalonia, Spain
Ana Belén Moreno-Castaño, MD

Medical Doctor
Hemostasis and Erythropathology Laboratory, Hematopathology, Department of Pathology, Centre de Diagnòstic Biomèdic (CDB), Hospital Clínic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
Barcelona, Catalonia, Spain
GE

Gines Escolar

MD PhD Senior Consultant
Hemostasis and Erythropathology Laboratory, Hematopathology, Department of Pathology, Centre de Diagnòstic Biomèdic (CDB), Hospital Clínic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
Barcelona, Catalonia, Spain
EC

Enric Carreras

Medical Doctor
Josep Carreras Leukaemia Research Institute, Hospital Clínic de Barcelona, Universitat de Barcelona, Barcelona, Spain.
Barcelona, Catalonia, Spain
MD

Maribel Diaz-Ricart

PhD Senior Consultant
Hemostasis and Erythropathology Laboratory, Hematopathology, Department of Pathology, Centre de Diagnòstic Biomèdic (CDB), Hospital Clínic de Barcelona, Institut d'Investigacions Biomèdiques August Pi i Sunyer (IDIBAPS), Universitat de Barcelona, Barcelona, Spain.
Barcelona, Catalonia, Spain
MB

Miquel Blasco

Doctor
Nephrology Unit, Hospital Clinic, Barcelona, Spain.
Barcelona, Catalonia, Spain
MP

Marc Pino

Laboratory Technician
Hemostasis and Erythropatology Laboratory, Pathology Department, CDB
Barcelona, Catalonia, Spain

Background: Recent studies demonstrated an involvement of the alternative complement pathway (aCP) in the pathogenesis of ANCA-associated vasculitis (AAV) where neutrophil extracellular traps (NETs) could be a key element between ANCA-induced neutrophil activation and aCP.

Aims: To study NETs role in complement dysregulation in AAV.

Methods: Blood samples were collected at diagnosis (AAV-t1) and at remission (AAV-t2) (n=13). Controls consisted of age and sex-matched individuals (n=10). TCP were analized by complement membrane attack complex (C5b-9) deposition on cultured endothelial cells (HMEC-1), by immunofluorescence, after exposing them to activated plasma. Results from were expressed as fold increase (mean±SEM) vs. those obtained with the pool of healthy subjects. Plasma levels of tCP and aCP soluble factors, such as sC5b-9 and sFBb (respectively), were also measured (mean±SEM). Circulating NETs were indirectly measured by quantifying circulant dsDNA plasmatic concentration (mean±SEM).

Results: AAV-t1 plasma increase C5b-9 deposition versus control (5.3±1.3 vs 1.2±0.2, p< 0.05). AAV-t2 samples induced less C5b-9 deposition than at AAV-t1 (0.9±0.2; p< 0.05), with values like controls. Levels of both sC5b-9 and sFBb were significantly increased in AAV-t1 vs. AAV-t2 (1882±418 ng/mL and 3.2±0.4 µg/mL vs 852±104 ng/mL and 1.9±0.2 µg/mL, respectively; p< 0.05). At AAV-t2, levels were similar to controls (708±42 ng/mL for sC5b-9, and 2.4±0.2 µg/mL for sFBb). Circulating NETs were also increased in AAV-t1 (22.2±3.5 µg/mL) compared to both AAV-t2 and controls (13.6±1.1 µg/mL and 13.7±0.3 µg/mL, respectively; p< 0.05). Moreover, NETs in AAV-t1 presented a significant correlation with sFBb levels, both in AAV-t1 (r=0,709; p< 0.05) and in AAV-t2 (r=0,585; p< 0.05).

Conclusion(s): There is a correlation between NETs, AAV activity and sFBb, which supports the role of NETs and cAP in AAV pathogenesis. Moreover, differences in C5b-9 deposition between the two stages of the disease suggest that tCP may be dysregulated in AAV.