Imbalance of tissue-type plasminogen activator (t-PA) and its specific inhibitor (PAI-1) in patients with rheumatoid arthritis associated with disease activity
The relationship between plasma fibrinogen, D-dimer (DD), t-PA and PAI-1 and their correlation with disease activity (DA) were studied in 45 patients with rheumatoid arthritis (RA) (group B) to further understand the implication of fibrinolysis in the pathophysiology of RA. The control group constituted 24 healthy subjects (group A). A Stoke index (SI) of DA was assigned to each patient. Patients were divided into two groups: C, minimal-mild DA (SI 1–7); D, moderate-severe DA (SI 8–17). Fibrinogen was elevated in RA correlating positively with SI and CRP. Hypercoagulability counteracted by reactive fibrinolysis was inferred from a 10-fold increase of DD in group B as compared to group A. The relatively lower levels of DD in group D compared to group C and their negative correlation with SI (rs=−0.45, −0.49, p=0.0006) indicate the tendency of fibrinolysis to decrease with the increase of DA. Significant elevation of t-PA and PAI-1 were found in group B compared to group A. While t-PA progressively decreased with the increase of DA (rs=−0.45, p=0.0019), a positive relation of PAI-1 to DA was observed (rs=0.42, p=0.0042). A 2-fold increase of PAI-1/t-PA molar ratio in group D compared to groups A and C as well as its positive correlation with SI (rs=0.63, p=0.0001) indicate the displacement of balance between t-PA and PAI-1 in favour of the inhibitor with the increase of DA in RA. The involvement of inflammatory mediators in PAI-1/t-PA imbalance was proposed from the relation of fibrinolytic abnormalities with the activity of systemic inflammatory process.