Fibrinogen Structural Changes and Their Potential Role in Endometriosis-Related Thrombosis

Abstract

Endometriosis (EM), a chronic inflammatory condition predominantly affecting women of reproductive age, has been linked to an elevated risk of thrombosis, though its underlying molecular mechanisms remain incompletely understood. In this case-control study, involving 71 EM patients and 71 matched controls, we explored the structural and functional changes in fibrinogen and their potential role in thrombosis. Key oxidative stress markers, such as reactive oxygen species (ROS) levels in blood lymphocytes, monocytes, and granulocytes, along with plasma lipid peroxidation markers and total antioxidant capacity, were measured. Fibrinogen structure was examined using circular dichroism spectroscopy and intrinsic fluorescence, while functional properties were evaluated by analyzing thrombin-mediated polymerization and plasmin-induced lysis. Compared to controls, EM patients exhibited elevated ROS production and systemic oxidative stress, leading to notable fibrinogen oxidation and structural alterations. These changes were associated with impaired fibrin polymerization and enhanced resistance to plasmin-induced lysis, which are indicative of a pro-thrombotic state. These findings suggest that oxidative stress-driven fibrinogen modifications may contribute to the heightened thrombotic risk in women with EM, highlighting a potential therapeutic target to mitigate cardiovascular complications.

Keywords: endometriosis; fibrinogen; oxidative stress; thrombosis.

Figure 1

Intracellular leukocyte ROS production by FACS analysis. (A) Representative gating strategy for identifying leukocyte subpopulations based on forward scatter (FSC-A) and side scatter (SSC-A) properties. Regions were defined to distinguish lymphocytes, monocytes, and granulocytes. (B–D) Histogram overlays showing ROS levels (measured as relative fluorescence units, RFUs) in lymphocytes (B), monocytes (C), and granulocytes (D) from endometriosis (EM) patients (red) and controls (green). (E–G) Quantification of ROS levels in lymphocytes (E), monocytes (F), and granulocytes (G) from controls and EM patients, expressed as relative fluorescence units (RFUs).

Figure 2

Plasma oxidative stress markers in EM patients. MDA (A), total antioxidant capacity (B) and nitrate/nitrite levels (C) in EM patients and controls.

Figure 3

Fibrinogen structural changes and oxidation in EM patients and controls. Representative fibrinogen circular dichroism spectra (fibrinogen secondary structure, (A)), intrinsic fibrinogen fluorescence (fibrinogen tertiary structure, (B)) and fibrinogen dityrosine content (fibrinogen oxidation, (C)) in EM patients and controls.

Figure 4

Fibrinogen functional modifications in EM patients compared to controls. Fibrinogen polymerization into fibrin in EM patients and controls is shown in Panel (A). Lag phase, maximum slope (Vmax), and maximum absorbance (Max abs) of fibrinogen polymerization curves in EM patients and controls are shown in the panels (B–D). The observed modifications are related to a different fibrinogen structure in EM fibrinogen compared to controls.

Figure 5

EM patients show fibrin resistance to plasmin-induced lysis. Representative gel showing fibrin degradation at 0 h, 3 h, and 6 h of plasmin digestion, with fibrinogen purified from EM patients and controls (A). Fibrin β chain degradation rates (B) in EM patients and controls.