Fibrinolysis/Proteolysis Balance in Stable Angina Pectoris in Relation to Angiographic Findings

Matrix metalloproteinases in coronary artery disease

Matrix metalloproteinases (MMP) are a family of zinc-containing endoproteinases that degrade extracellular matrix (ECM) components. MMP have important roles in the development, physiology and pathology of cardiovascular system. Metalloproteases also play key roles in adverse cardiovascular remodeling, atherosclerotic plaque formation and plaque instability, vascular smooth muscle cell (SMC) migration and restenosis that lead to coronary artery disease (CAD), and progressive heart failure. The study of MMP in developing animal model cardiovascular systems has been helpful in deciphering numerous pathologic conditions in humans. Increased peripheral blood MMP-2 and MMP-9 in acute coronary syndrome (ACS) may be useful as noninvasive tests for detection of plaque vulnerability. MMP function can be modulated by certain pharmacological drugs that can be exploited for treatment of ACS. CAD is a polygenic disease and hundreds of genes contribute toward its predisposition. A large number of sequence variations in MMP genes have been identified. Case-control association studies have highlighted their potential association with CAD and its clinical manifestations. Although results thus far are inconsistent, meta-analysis has demonstrated that MMP-3 Glu45Lys and MMP-9 1562C/T gene polymorphisms were associated with CAD risk.

Metaloproteasas, remodelado vascular y syndromes aterotrombóticos

Defects in the synthesis and breakdown of the extracellular matrix (ECM) are now seen as key processes in the development of atherosclerosis and its thrombotic complications. Correlations have been observed between circulating levels of ECM biomarkers and the clinical manifestations of and risk factors for atherosclerosis. Several matrix metalloproteinases (MMPs), endopeptidases that can degrade the ECM, such as MMP-9 and MMP-10, play important roles in the pathophysiology of atherothrombosis and contribute to the expansion of abdominal aortic aneurysms. Moreover, they may also be useful biomarkers of atherosclerotic risk and serve as predictors of coronary and cerebrovascular disease recurrence. Although at present the effect of tissue inhibitors of MMPs (TIMPs) on cardiovascular disease prognosis is still uncertain, the ECM could be a promising therapeutic target in atherothrombotic disease, and several MMP inhibitors are currently undergoing clinical trials.

Anti-inflammatory therapy of dry eye

As tear secretion and tear clearance decrease in the dry eye, an inflammatory response is initiated on the ocular surface that appears to involve both soluble and cellular mediators. Although the traditional approach to treating dry eye is to hydrate and lubricate the ocular surface with artificial tears, symptoms and/or sight-threatening corneal disease may persist in some patients on such aqueous enhancement therapies. In these patients, treatment with anti-inflammatory agents, such as cyclosporin A, corticosteroids, tetracyclines, or autologous serum, may be considered. Results of studies investigating the use of these agents are discussed. During treatment, patients should be conscientiously monitored for adverse effects.

Plasminogen and plasmin activity in patients with coronary artery disease

OBJECTIVE

While coronary artery disease (CAD) is associated with disturbances of the plasma fibrinolytic system, the nature of these disturbances is not fully defined. Fibrinolysis is regulated by plasmin, whose production is mediated by plasminogen activator conversion of plasminogen (Plg) to plasmin. The cascade is modulated by feedback loops that include Plg activator inhibitor 1 (PAI-1). Molecular interactions with Plg kringle domains play an important role in regulating plasmin production and its modulation of fibrinolysis. We hypothesized that interactions of tissue plasminogen activator (tPA) with Plg kringle domains regulates plasmin levels in patients with stable CAD.

METHODS

Plasma was collected from patients (n = 33) with an angiographically significant CAD and controls (n = 18) with angiographically established normal or minimally diseased arteries. Plasmin activity, tPA activity, and plasma levels of Plg, PAI-1, uPA, and tPA were determined.

RESULTS

CAD patients had 1.7-fold greater plasmin activity (P = 0.02) that correlated with 1.5-fold higher tPA activity when compared to controls. Epitope mapping of Plg domains showed Plg differences in epitope exposure between the two groups. Plasma from CAD patients had 50% less (P < 0.001) detectable kringle 4 and 48% less (P = 0.007) detectable kringles 1-3.

CONCLUSIONS

Based on detectable differences in Plg, we conclude that in patients with stable CAD, Plg complexed with tPA exists in a conformation that enables increased tPA activity and Plg conversion to plasmin.

Antiinflammatory therapy for dry eye

PURPOSE

To present evidence establishing the relationship between inflammation and dry eye and supporting the use of antiinflammatory therapy for dry eye.

DESIGN

Analysis of literature.

METHODS

Research studies that evaluated inflammation in dry eye pathogenesis and clinical trials of antiinflammatory therapies for dry eye were reviewed.

RESULTS

There is increasing evidence that decreased tear secretion, decreased tear turnover, and desiccation promote inflammation on the ocular surface. An increase in soluble mediators (cytokines and proteases) in the tear fluid, adhesion molecule expression by the conjunctival epithelium, and T-cell infiltration of the conjunctiva have been observed in dry eye patients. This inflammation appears to have a role in the pathogenesis of the ocular surface epithelial disease, termed keratoconjunctivitis sicca (KCS), that develops in dry eye. Clinical improvement of KCS has been observed after therapy with antiinflammatory agents including corticosteroids, cyclosporin and doxycycline. Cyclosporin A emulsion was approved by the Food and Drug Administration as therapy for dry eye. Randomized placebo-controlled FDA clinical trials showed that cyclosporine A was superior to vehicle in stimulating aqueous tear production, decreasing corneal punctuate fluorescein staining, reducing symptoms of blurred vision, and decreasing artificial tear use in patients with KCS. No ocular or systemic toxicity was observed from this medication.

CONCLUSIONS

Ocular surface and lacrimal gland inflammation has been identified in dry eye that plays a role in the pathogenesis of KCS. Antiinflammatory therapy has efficacy for treating KCS. Cyclosporin A is the first FDA approved therapy for this indication. It improved signs and symptoms of KCS, and it is safe for long-term use.

Is thrombogenesis in atrial fibrillation related to matrix metalloproteinase-1 and its inhibitor, TIMP-1?

BACKGROUND AND PURPOSE

Decreased matrix metalloproteinase-1 (MMP-1) and increased levels of its inhibitor, tissue inhibitor of matrix metalloproteinase-1 (TIMP-1), reflect impaired matrix degradation with an increase in fibrosis. A prothrombotic state has been described in atrial fibrillation (AF), increasing the risk of stroke and thromboembolism. Because structural abnormalities and remodeling of atria have been observed in AF, we hypothesized that the prothrombotic state in AF may be related to abnormal indexes of matrix degradation.

METHODS

We studied 48 consecutive patients (30 men; age, 70.5+/-9.0 years) with chronic nonrheumatic AF who were not on anticoagulation. Plasma levels of MMP-1, TIMP-1, and prothrombin fragment 1+2 (F1+2, an index of thrombogenesis) were measured by enzyme-linked immunosorbent assay. M-mode, 2-dimensional, and Doppler echocardiographic studies were performed in all patients. Research indexes were compared with data from 32 control subjects in sinus rhythm who were of similar age and sex.

RESULTS

Patients with AF had lower levels of MMP-1 (P=0.011) but increased levels of TIMP-1 (P=0.033) and F1+2 (P<0.001) and a higher ratio of TIMP-1 to MMP-1 (P=0.009) compared with control subjects. After adjustment for sex, age, hypertension, and diabetes, TIMP-1 levels and the ratio of TIMP-1 to MMP-1 correlated with F1+2 levels (r=0.24, P=0.038; and r=0.26, P=0.023, respectively). In multivariate analysis, there was no independent relationship between MMP-1, TIMP-1, or ratio of TIMP-1 to MMP-1 and the presence of AF.

CONCLUSIONS

Patients with AF have evidence of impaired matrix degradation, but this was not independently associated with the presence of AF on multivariate analysis. However, an independent relationship was found between the MMP/TIMP system and prothrombotic state (assessed by F1+2 levels).