Protein S and protein C anticoagulant activity in acute and chronic cardiac ischemic syndromes. Relationship to inflammation, complement activation and in vivo thrombin activity

Advances and Challenges in Targeting TGF-β Isoforms for Therapeutic Intervention of Cancer: A Mechanism-Based Perspective

The TGF-β family is a group of 25 kDa secretory cytokines, in mammals consisting of three dimeric isoforms (TGF-βs 1, 2, and 3), each encoded on a separate gene with unique regulatory elements. Each isoform plays unique, diverse, and pivotal roles in cell growth, survival, immune response, and differentiation. However, many researchers in the TGF-β field often mistakenly assume a uniform functionality among all three isoforms. Although TGF-βs are essential for normal development and many cellular and physiological processes, their dysregulated expression contributes significantly to various diseases. Notably, they drive conditions like fibrosis and tumor metastasis/progression. To counter these pathologies, extensive efforts have been directed towards targeting TGF-βs, resulting in the development of a range of TGF-β inhibitors. Despite some clinical success, these agents have yet to reach their full potential in the treatment of cancers. A significant challenge rests in effectively targeting TGF-βs' pathological functions while preserving their physiological roles. Many existing approaches collectively target all three isoforms, failing to target just the specific deregulated ones. Additionally, most strategies tackle the entire TGF-β signaling pathway instead of focusing on disease-specific components or preferentially targeting tumors. This review gives a unique historical overview of the TGF-β field often missed in other reviews and provides a current landscape of TGF-β research, emphasizing isoform-specific functions and disease implications. The review then delves into ongoing therapeutic strategies in cancer, stressing the need for more tools that target specific isoforms and disease-related pathway components, advocating mechanism-based and refined approaches to enhance the effectiveness of TGF-β-targeted cancer therapies.

Interleukin-6 induction of protein s is regulated through signal transducer and activator of transcription 3

OBJECTIVE

The protein C anticoagulant pathway is an essential process for attenuating thrombin generation by the membrane-bound procoagulant complexes tenase and prothrombinase. In this pathway, protein S (PS) serves as a cofactor for activated protein C. PS circulates in plasma both in a free form and in complex with complement component 4b-binding protein (C4BP). C4BP is a known acute phase reactant, thereby suggesting a relation between PS and the acute phase response. Interleukin (IL)-6 has been shown to increase both PS and C4BP gene expression. Our objective was to study the regulation of PS gene expression by IL-6 in detail.

METHODS AND RESULTS

IL-6 upregulates both PS mRNA and protein levels in liver-derived HepG2 cells. The promoter of the PS gene (PROS1) was cloned upstream from a luciferase reporter gene. After transfection in HepG2 cells, the luciferase activity was shown to be stimulated by the addition of IL-6. IL-6 exerts its effect through Signal Transducer and Activator of Transcription 3 (STAT3) that interacts with the PROS1 promoter at a binding site in between nucleotides 229 to 207 upstream from the translational start.

CONCLUSIONS

IL-6 induces PS expression via STAT3. A possible function for IL-6-induced PS expression in cell survival is discussed.

Echis time, under-carboxylated prothrombin and vitamin K status in intensive care patients

Vitamin K deficiency is a known cause of coagulopathy in hospitalized patients, but the extent of the problem has not been well assessed. This noninterventional, prospective observational study of 35 adults was undertaken in the intensive care unit (ICU) and examined the incidence of and the methods for diagnosing vitamin K deficiency. Measurements of prothrombin time, Echis time and plasma concentrations of under-carboxylated prothrombin (proteins induced in vitamin K absence or antagonism, PIVKA-II), vitamin K1 and ferritin were made during the 48 h after admission to the unit and repeated if coagulopathy developed later. Plasma vitamin K1 was low in 15 admissions (43%), in 11 cases of patients with coagulopathy and in four cases without coagulopathy. PIVKA-II was present in 12 cases (34%), of whom four had low vitamin K1 levels. All of the eight patients with raised PIVKA-II but normal vitamin K concentration were hyperferritinaemic. We conclude that low plasma vitamin K levels, suggestive of low tissue stores, are common in intensive care patients with or without coagulopathy. As 34% of patients had a raised PIVKA-II, this suggests that vitamin K stores may be insufficient to maintain full gamma-carboxylation of prothrombin and emphasize the need to anticipate vitamin K deficiency in the ICU setting by appropriate supplementation.

A review of the technical, diagnostic, and epidemiologic considerations for protein S assays

OBJECTIVES

To review the state of the art relating to protein S deficiency as a risk factor for thrombosis and to make recommendations regarding the use of protein S measurements in the assessment of thrombotic risk in individual patients and families.

DATA SOURCES, EXTRACTION, AND SYNTHESIS

Selection criteria were developed for the inclusion of publications from 1985 to 2001 based on the relevant literature concerned with the systematic review of diagnostic tests. Minimal selection criteria were agreed on and the articles stratified into level 1 if they met these criteria and level 2 if they did not meet these criteria. The included articles were reviewed by the authors and abstracted onto predetermined data collection forms. These forms were then scored and recommendations based on level 1 studies. As described elsewhere, results of discussions at the College of American Pathologists Conference XXXVI on Diagnostic Issues in Thrombophilia were used to revise the manuscript into its final form.

CONCLUSIONS

Consensus was reached on 16 recommendations for the use of protein S assays in the assessment of thrombotic risk in individuals and families. Two themes run through the conclusions. First, protein S assays are the most technically problematic of the assays reviewed at this conference. Second, only 2 papers evaluating the diagnostic use of protein S assays met our level 1 inclusion criteria. These 2 problems point out the need for better standardized assays and rigorous studies of the diagnostic utility of these assays.

Sex hormone binding globulins and atherosclerotic risk in systemic lupus

Sex hormone binding globulin (SHBG) is a transport protein in human plasma which regulates the bioavailability of sex hormones, mediates membrane receptor signaling and may affect inflammatory processes, suggesting a regulatory role for this protein in the prevention of atherosclerosis. The current report summarizes literature implicating several members of the SHBG family in the regulation of hormonal and inflammatory processes which may be pertinent to the accelerated atherosclerosis seen in systemic lupus.

Effects of a novel Mac-1 inhibitor, NPC 15669, on hemostatic parameters during preconditioned myocardial infarction

NPC 15669, a member of the leumedins family, inhibits leukocyte adhesion to the endothelium by blockage of upregulation of a member of beta2 integrin family Mac-1 (CD11b/CD18). Inhibition of neutrophil-endothelial interactions may alter the course of myocardial reperfusion injury. However, the effects of NPC 15669 supplementation on the hemostatic profile during ischemia-reperfusion are unknown. The aim of the present study was to define changes in the certain hemostatic factors in the natural course of preconditioned myocardial infarction. Twelve consecutive Yorkshire swine underwent myocardial stunning (8 min. left anterior descending artery occlusion followed by 90 min. of reperfusion) and then preconditioned myocardial infarction (50 min. occlusion followed by 3 hours of reperfusion) experiments. NPC 15669 (10 mg/kg loading dose followed by constant infusion at 6 mg x kg(-1) x h(-1)) was administered in 6 animals; another 6 swine received saline and served as controls. Blood samples were obtained at baseline, twice during occlusion; and three times during reperfusion. The levels of antithrombin-III, Protein C, total Protein S, fibronectin, endothelin-1, as well as the stable metabolites of thromboxane (TxB2) and prostacyclin (6-keto-PGF1a), were determined. NPC 15669 treatment was associated with diminished endothelin-1, TxB2 levels and increased fibronectin, 6-keto-PGF1a, Protein C and total Protein S concentrations in the setting of preconditioned myocardial infarction. There were no changes in the plasma concentrations of antithrombin-III in NPC 15669 group when compared with controls. The increase in Protein C, total Protein S, and 6-keto-PGF1a (favoring antithrombosis), and decrease in endothelin-1 and TxB2 levels (favoring vasodilatation), following NPC 15669 may explain the reduction in infarct size previously reported with this agent.

Mild myocardial stunning affects platelet aggregation and certain hemostatic factors in swine

Myocardial stunning is characterized by transient contractile dysfunction occurring subsequent to an episode of ischemia followed by reperfusion. Platelet activation and hemostatic abnormalities have been described in patients with unstable angina and acute myocardial infarction, however, their role in the pathogenesis of myocardial stunning is unknown. The purpose of this study was to determine if platelet aggregation and certain hemostatic factors change during myocardial stunning following brief coronary arterial occlusion. Nine Yorkshire swine underwent left anterior descending coronary artery occlusion for 8 minutes followed by 90 minutes of reperfusion. Blood samples were obtained at baseline, at 4 and 8 minutes of occlusion, and at 60 and 90 minutes of reperfusion. Platelet aggregability and concentrations of antithrombin III, protein C, protein S, fibronectin, endothelin 1, and the stable metabolites of thromboxane (TxB2) and prostacyclin (6-keto-PGF1a) were measured in systemic circulation. The occlusion phase was associated with a decline of endothelin 1 (-13.6%), and TxB2 (-19.6%), and elevation of antithrombin III (+40.2%) and protein C (+22.9%). Mild myocardial stunning was associated with a significant increase in platelet aggregation (+33.7%), endothelin-1 (+24.7%), 6-keto-PGF1a (+41.5%), TxB2 (+11.9%), and protein C (+42.3%) during the reperfusion phase. There were no changes in plasma fibronectin and total protein S. Thus, mild myocardial stunning following brief coronary artery occlusion is associated with substantial dynamic changes in platelet aggregability and certain hemostatic factors. These results may be relevant to understanding the mechanisms determining myocardial stunning and coronary arterial patency following reperfusion.

Thrombin-antithrombin III complex in acute retinal vein occlusion

PURPOSE

To determine whether quantitative differences in systemic hypercoagulable state could be identified among patients with retinal vein occlusion at various sites of occlusion.

METHODS

The value of thrombin-antithrombin III complex was determined in 57 patients with retinal vein occlusion within 1 month after the subjective onset of retinal vein occlusion and in 15 age-matched normal controls.

RESULTS

Levels of log thrombin-antithrombin III complex were significantly higher in the patients with proximal retinal vein occlusion in which the occlusion site is at the optic disc (mean +/- SD, 0.493 +/- 0.389) than in those with distal retinal vein occlusion in which the occlusion site is away from the optic disc (0.312 +/- 0.150, P = .025) and in the normal controls (0.294 +/- 0.151, P = .020). There was no significant difference between the distal retinal vein occlusion and the normal controls (P = .720). More patients with proximal retinal vein occlusion showed elevated thrombin-antithrombin III complex values more than 3.9 ng/ml than those with distal retinal vein occlusion (8/29 vs 1/28, P = .025). Of nine patients showing an initial value of thrombin-antithrombin III complex of more than 3.9 ng/ml, repeated measurements were obtained in eight patients, who showed reduced value of thrombin-antithrombin III complex in the normal range in several months.

CONCLUSIONS

A systemic hypercoagulable state, which could be demonstrated with the elevation of thrombin-antithrombin III complex value, may contribute more to the development of retinal vein occlusion with thrombus at or near the trunk of the central retinal vein than those with thrombus at branch veins away from the optic disc in the retina.