Detection of Citrullinated Fibrin in Plasma Clots of Rheumatoid Arthritis Patients and Its Relation to Altered Structural Clot Properties, Disease-Related Inflammation and Prothrombotic Tendency

Abstract

AimsThe risk of cardiovascular events in patients with Rheumatoid Arthritis (RA) is disproportionately heightened as a result of systemic inflammation. The relative effect of autoimmune-associated citrullination on the structure and thrombotic potential of fibrin(ogen) remains unknown. We therefore compared indices of vascular function, inflammation, coagulation and fibrin clot composition in RA patients with healthy controls and evaluated parameter association with disease presence.MethodsBlood samples were collected from 30 RA patients and 30 age- and gender-matched healthy volunteers. Levels of serum amyloid A (SAA), c-reactive protein (CRP), soluble intercellular adhesion molecule 1 (sICAM-1) and soluble vascular cell adhesion molecule 1 (sVCAM-1) was measured using a sandwich immunoassay. Whole blood coagulation was assessed using Thromboelastography (TEG®). Fibrin clot networks and fiber structure was investigated using Scanning Electron Microscopy. The detection and quantification of citrullination in formed fibrin clots was performed using a fluorescently labeled Citrulline monoclonal antibody with Fluorescence Wide Field Microscopy.ResultsConcentrations of SAA, CRP and ICAM-1 were significantly elevated in RA patients compared to controls. TEG parameters relating to coagulation initiation, rate of fibrin cross-linking, and time to reach maximum thrombus generation were attenuated in RA patients. Microscopic analysis revealed denser networks of thicker fibrin fibers in RA patients compared to controls and multiple citrullinated regions within fibrin clot structures in RA patients were present.ConclusionOur findings provide novel evidence for the citrullination of fibrin within vasculature is more prominent in RA plasma compared to control plasma and plasma is more accessible than synovial fluid. Citrullinated fibrinogen could play a role as a determinant of thrombotic risk in RA patients.

A central role for amyloid fibrin microclots in long COVID/PASC: origins and therapeutic implications

“…While the list of the many other molecules that can plausibly effect this anomalous amyloid-type clotting is unclear, such clots may also be observed in the blood of individuals with inflammatory diseases such as Alzheimer's [37,50,59-61], Parkinson's [37,48], type 2 diabetes [37,38,[62][63][64], and rheumatoid arthritis [65][66][67][68]. Similar phenomena have also been observed in the pregnancy disorder pre-eclampsia [69], where there is also strong evidence for a microbial component [70,71].…”

“…Note that clots of fibrinaloid that have already formed are effectively inert and invisible to such methods. Here the method of choice is known as Thromboelastography (TEG) [48,52,56,58,59,65,66,108,109,[161][162][163][164][165] (or a related version known as ROTEM [166][167][168][169][170][171][172][173]). Figure 8 shows stylized traces of TEG, as typically found in health and disease.…”

Pathogenic implications, incidence, and outcomes of COVID-19 in autoimmune inflammatory joint diseases and autoinflammatory disorders

“…In fact, during these diseases, the pro-inflammatory milieu may induce a hyper-coagulation by an upregulation of procoagulant factors and a simultaneous downregulation of anticoagulant and fibrinolytic systems, thus leading to this clinical phenotype [79]. This risk is also associated with traditional CVD risk factors, such as an older age and diabetes, but also with the burden of the pro-inflammatory process over time and specific disease features [80,81]. Taking together these observations, an accurate evaluation of the hyper-coagulation burden in the patients with RMDs affected by SARS-CoV2 infection is needed, since possibly associated with a worse prognosis.…”

Fibrin deposition associates with cartilage degeneration in arthritis

“…It is also unclear whether fibrin fibers, which are thicker in RA patients than in healthy controls, are, e.g., less susceptible for fibrinolysis and thus more chondrotoxic. 46 …”

“…Finally, fibrin(ogen) citrullination has been demonstrated in RA and links the formation of autoantibodies to coagulation activation in RA. 46 , 54 Citrullinated fibrin(ogen) potentially can interact with amyloid-b protein and modify its coagulation properties. 55 …”