Stimulation of plasminogen activator and inhibitor in the lymphatic endothelium

Coagulation in Lymphatic System

The lymphatic system maintains homeostasis of the internal environment between the cells in tissues and the blood circulation. The coagulation state of lymph is determined by conditions of coagulation factors and lymphatic vessels. Internal obliteration, external compression or abnormally increased lymphatic pressure may predispose to localized lymphatic coagulation. In physiological conditions, an imbalance of antithrombin and thrombokinase reduces lymphatic thrombosis. However, the release of factor X by lymphatic endothelium injury may trigger coagulation casacade, causing blockage of lymphatic vessels and lymphedema. Heterogeneity of lymphatic vessels in various tissues may lead to distinct levels and patterns of coagulation in specific lymphatic vessels. The quantitative and qualitative measurement of clotting characteristic reveals longer time for clotting to occur in the lymph than in the blood. Cancer, infections, amyloidosis and lymph node dissection may trigger thrombosis in the lymphatic vessels. In contrast to venous or arterial thrombosis, lymphatic thrombosis has rarely been reported, and its actual prevalence is likely underestimated. In this review, we summarize the mechanisms of coagulation in lymphatic system, and discuss the lymphatic thrombosis-related diseases.

Sealing of the mediastinum with a local hemostyptic agent reduces chest tube duration after complete mediastinal lymph node dissection for stage I and II non-small cell lung carcinoma

BACKGROUND

We assessed the impact of coverage of the mediastinum with a local hemostyptic agent as well as the impact of perioperative thromboembolic prophylaxis on cumulative chest drain volume and on the duration of chest tubes after surgical resection with complete mediastinal lymph node dissection for stage I or II non-small cell lung cancer.

METHODS

In a prospective, randomized two-by-two factorial design, 80 patients with clinical stage I or II non-small cell lung cancer were allocated to one of two surgical therapy arms (TachoComb or conventional surgical hemostasis) and one of two anticoagulation arms (enoxaparin 4,000 IU or dalteparin 5,000 IU). Primary end point was cumulative chest drain volume; secondary end point was duration of chest tubes. Additionally clinical data were obtained.

RESULTS

Comparison of the surgical arms revealed significantly lower cumulative chest drain volumes and thereby an earlier chest tube removal in the TachoComb group (p = 0.045). With regard to thromboembolic prophylaxis, a significantly earlier chest tube removal was found for patients treated with dalteparin (p = 0.039). Analysis of the interaction of surgical and anticoagulation treatment revealed the combined use of TachoComb and dalteparin was superior to other combinations (cumulative chest drain volumes 498 +/- 67 mL versus 1,000 +/- 88 mL, 924 +/- 87 mL, and 895 +/- 118 mL; p = 0.008; mean duration of chest tubes 1.78 +/- 0.15 days versus 2.96 +/- 0.21 days, 2.93 +/- 0.17 days, and 3.06 +/- 0.27 days; p = 0.019).

CONCLUSIONS

The combined use of a local hemostyptic agent and dalteparin seems superior as compared with other regimens of hemostasis and thromboembolic prophylaxis in patients undergoing surgical resection and complete mediastinal lymph node dissection for stage I and II non-small cell lung cancer with regard to cumulative chest drain volume as well as duration of chest tubes.

The effect of TGF-beta2 on human trabecular meshwork extracellular proteolytic system

Our study aimed to investigate whether transforming growth factor-beta2 (TGF-beta2), increased in the aqueous humor of eyes with primary open angle glaucoma (POAG), can affect factors responsible for the activity of matrix metalloproteinases (MMPs) in human trabecular cell cultures. With this goal in mind cultures of human trabecular meshwork (hTM) cells derived from 8 donors were treated with TGF-beta2 for 24, 36 and 48 hr. Influence of TGF-beta2 on expression of MMP-2, MMP-9, membrane type 1-MMP (MT1-MMP) and plasminogen activator inhibitor-1 (PAI-1) was examined using RT-PCR, Northern Blot, Western Blot and zymography. The influence of TGF-beta2 treatment on PAI-1 expression was also investigated using immunohistochemistry. It appeared that treatment with TGF-beta2 significantly increased expression of the proform of MMP-2, whereas the active form was not detectable. MMP-9 and MT1-MMP expression were not influenced by TGF-beta2 treatment. There was, however, a significant increase in PAI-1 expression. To investigate whether transformation of the proform of MMP-2 to the active form was inhibited by PAI-1, the influence of treatment with TGF-beta2 and a PAI-1 neutralizing antibody on MMP-2 was investigated using zymogram method. With this treatment protocol the active form of MMP-2 was clearly visible, indicating that TGF-beta2 enhancement of the PAI-1-expression decreases MMP activity. Inhibition of MMP activity through elevated levels of TGF-beta2 might contribute to the increase in ECM in the trabecular meshwork of glaucomatous eyes.

Proteomic technologies to study diseases of the lymphatic vascular system

Now that the human genome has been mapped, a new challenge has emerged: deciphering the various products of individual genes. Consequently, new proteomic technologies are being developed to monitor and identify protein function and interactions responsible for the total activities of the cell. The application of these new proteomic technologies to study cellular activities, will lead to a faster sample throughput and increased sensitivity for the detection of individual proteins, thus providing major opportunities for the discovery of new biomarkers for the early detection of protein alterations associated with the progression of the disease state.

Role of the matrix metalloproteinase and plasminogen activator-plasmin systems in angiogenesis

Extracellular proteolysis is an absolute requirement for new blood vessel formation (angiogenesis). This review examines the role of the matrix metalloproteinase (MMP) and plasminogen activator (PA)-plasmin systems during angiogenesis. Specifically, a role for gelatinases (MMP-2, MMP-9), membrane-type 1 MMP (MMP-14), the urokinase-type PA receptor, and PA inhibitor 1 has been clearly defined in a number of model systems. The MMP and PA-plasmin systems have also been implicated in experimental vascular tumor formation, and their role during this process will be examined. Antiproteolysis, particularly in the context of angiogenesis, has become a key target in therapeutic strategies aimed at inhibiting tumor growth and other diseases associated with neovascularization.