Prothrombin fragments in cardiovascular disease

Marine omega-3 fatty acid supplementation in non-alcoholic fatty liver disease: Plasma proteomics in the randomized WELCOME* trial

BACKGROUND & AIMS

Non-alcoholic fatty liver disease (NAFLD) is a liver condition characterised by liver fat accumulation and often considered to be the liver manifestation of metabolic syndrome. The aim of this study was to examine in patients with NAFLD the system-wide effects of treatment with docosahexaenoic acid + eicosapentaenoic acid (DHA + EPA) versus placebo on the plasma proteome.

METHODS

Plasma from patients that participated in a 15-18 months randomised, double-blind placebo-controlled trial testing the effects of 4 g DHA + EPA daily was analysed using depletion-free quantitative proteomics.

RESULTS

Bioinformatics interpretation of the proteomic analysis showed that DHA + EPA treatment affected pathways involving blood coagulation, immune/inflammatory response and cholesterol metabolism (p < 0.05). Two key proteins of cardiovascular risk, prothrombin and apolipoprotein B-100, were shown to decrease as a result of DHA + EPA supplementation [Prothrombin: Males DHA + EPA Mean iTRAQ log₂ratio (SD) = -0.13 (0.20) p = 0.05, Females DHA + EPA Mean iTRAQ log₂ratio (SD) = -0.48 (0.35) p = 0.03; Apo B-100: Males DHA + EPA Mean iTRAQ log₂ratio (SD) = -0.24 (0.16) p = 0.01, Females DHA + EPA Mean iTRAQ log₂ratio (SD) = -0.15 (0.05) p = 0.02].

CONCLUSIONS

Plasma proteomics applied in a randomised, placebo-controlled trial showed that high dose DHA + EPA treatment in patients with NAFLD affects multiple pathways involved in chronic non-communicable diseases.

The causes of thrombocytopenia after transcatheter aortic valve implantation

INTRODUCTION

Even though thrombocytopenia following transcatheter aortic valve implantation (TAVI) has been described, further investigation of this phenomenon is needed.

AIMS

To determine which factors may explain the fall in platelet count that occurs after implantation of a TAVI device, including markers of platelet and blood coagulation activation.

MATERIAL AND METHODS

32 patients without previous indications for dual antiplatelet therapy (mean age 78.5±7.9 years, 62% females) with severe aortic valve stenosis (mean gradient 54.6±16.9mmHg) who qualified for TAVI procedure (Edwards Sapien XT) were prospectively analyzed. Platelet counts were analyzed before the surgery, on the day of the procedure and for the three following postoperative days (POD 1 to 3). To assess platelet activation P-selectin (PS, serum) and platelet factor 4 (PF-4, CTAD plasma) were measured, whereas for the evaluation of coagulation activation prothrombin fragments 1+2 (F1+2, plasma) were assessed before the procedure, on POD-1 and POD-3 (ELISA).

RESULTS

During the postoperative period a significant platelet count drop, the most evident on POD-2, was observed followed by a platelet count raise. The platelet count drop correlated directly with the amount of iodinated contrast agent (r=0.42, p=0.016) and inversely with baseline mean platelet volume (r=-0.37, p=0.046). Neither clinical nor perioperative parameters, except contrast medium, influenced platelet count decrease. No significant differences regarding the concentration of the evaluated markers in patients with and without thrombocytopenia were found. PF-4 and F1+2 significantly changed during the study (p<0.05). Greater acute PF-4 decrease correlated with greater acute platelet count drop (r=0.48, p=0.043), and during the study slower PF-4 increase correlated with higher platelet count increase on POD-3 (r=-0.505, p=0.032). Lower baseline PS correlated with lower baseline platelet count and higher platelet count increase on POD-3 (r=0.45, p=0.04 and =-0.55, p=0.02, respectively). No significant correlations between F1+2 concentrations and platelet count changes have been found.

CONCLUSIONS

Platelet reduction shortly after TAVI procedure is related to the amount of contrast agent applied during the procedure. Platelet activation and blood coagulation along with impaired baseline platelet renewal might be the mechanisms of thrombocytopenia following TAVI procedure.

Activation of NLRP3 inflammasome complex potentiates venous thrombosis in response to hypoxia

Venous thromboembolism (VTE), caused by altered hemostasis, remains the third most common cause of mortality among all cardiovascular conditions. In addition to established genetic and acquired risk factors, low-oxygen environments also predispose otherwise healthy individuals to VTE. Although disease etiology appears to entail perturbation of hemostasis pathways, the key molecular determinants during immediate early response remain elusive. Using an established model of venous thrombosis, we here show that systemic hypoxia accelerates thromboembolic events, functionally stimulated by the activation of nucleotide binding domain, leucine-rich-containing family, pyrin domain containing 3 (NLRP3) inflammasome complex and increased IL-1β secretion. Interestingly, we also show that the expression of NLRP3 is mediated by hypoxia-inducible factor 1-alpha (HIF-1α) during these conditions. The pharmacological inhibition of caspase-1, in vivo knockdown of NLRP3, or HIF-1α other than IL-1β-neutralizing antibodies attenuated inflammasome activation and curtailed thrombosis under hypoxic conditions. We extend the significance of these preclinical findings by studying modulation of this pathway in patients with altitude-induced venous thrombosis. Our results demonstrate distinctive, increased expression of NLRP3, caspase-1, and IL-1β in individuals with clinically established venous thrombosis. We therefore propose that an early proinflammatory state in the venous milieu, orchestrated by the HIF-induced NLRP3 inflammasome complex, is a key determinant of acute thrombotic events during hypoxic conditions.

Does limb preconditioning reduce pain after total knee arthroplasty? A randomized, double-blind study

BACKGROUND

Total knee arthroplasty (TKA) can be associated with considerable postoperative pain. Ischemic preconditioning of tissue before inducing procedure-related underperfusion may reduce the postoperative inflammatory response, which further may reduce associated pain.

QUESTIONS/PURPOSES

In this prospective, randomized study, we aimed at evaluating the impact of ischemic preconditioning on postoperative pain at rest and during exercise; use of pain medication; levels of systemic prothrombotic and local inflammatory markers; and length of stay and achievement of physical therapy milestones.

METHODS

Sixty patients undergoing unilateral TKA under tourniquet were enrolled with half (N = 30) being randomized to an episode of limb preconditioning before induction of ischemia for surgery (tourniquet inflation). Pain scores, analgesic consumption, markers of inflammation (interleukin-6 [IL-6], tumor necrosis factor [TNF]-α in periarticular drainage), and periarticular circumference were measured at baseline and during 2 days postoperatively. Changes in prothrombotic markers were evaluated.

RESULTS

Patients in the preconditioning group had significantly less pain postoperatively at rest (mean difference = -0.71, 95% confidence interval [CI] = -1.40 to -0.02, p = 0.043) and with exercise (mean difference = -1.38, 95% CI = -2.32 to -0.44, p = 0.004), but showed no differences in analgesic consumption. No differences were seen between the study and the control group in terms of muscle oxygenation and intraarticular levels of IL-6 and TNF-α as well as levels of prothrombotic markers. No differences were found between groups in regard to hospitalization length and time to various physical therapy milestones.

CONCLUSIONS

Ischemic preconditioning reduces postoperative pain after TKA, but the treatment effect size we observed with the preconditioning routine used was modest.

CLINICAL RELEVANCE

Given the ease of this intervention, ischemic preconditioning may be considered as part of a multimodal analgesic strategy. However, more study into the impact of different preconditioning strategies, elucidation of mechanisms, safety profiles, and cost-effectiveness of this maneuver is needed.

Urinary prothrombin fragment 1+2 in patients with venous thrombosis and myocardial infarction

Patients with venous-thromboembolism (VTE) and myocardial infarction (MI) have elevated prothrombin fragment 1+2 (F1+2) levels. In patients with postoperative VTE, urinary F1+2 (uF1+2) was higher than in individuals without VTE. To explore the relationship between plasma and uF1+2 we performed a pilot study in patients with thrombotic events and healthy controls. In 40 patients with VTE or MI, and 25 age- and sex-matched healthy controls, F1+2 and D-dimer levels were measured in urine and plasma within 48 h after diagnosis. In addition, in all subjects renal function was assessed. Plasma and uF1+2 levels were positively correlated. Compared to controls, patients with VTE had higher levels of both plasma F1+2 (271 vs 160 pmol L(-1), p < 0.05) and uF1+2 levels (38 vs 28 pmol L(-1)), the latter, however, was not statistically significant. Patients with acute MI had similar F1+2 levels as controls in both plasma and urine. Differences in urinary F1+2 levels could not be attributed to differences in concentrations of creatinine or albumin in spot urine samples. Overall, D-dimer and F1+2 levels in urine were extremely low in all groups.

Linking inflammation and coagulation: novel drug targets to treat organ ischemia

PURPOSE OF REVIEW

Activation of the coagulation system during ischemia/reperfusion injury is an unavoidable event and even further augmented during cardiovascular surgery. Clotting not only leads to disturbance of blood rheology but also enhances the inflammatory response. We aim to highlight the inflammatory properties of the coagulation system and novel potential therapeutic approaches targeting both features.

RECENT FINDINGS

Heparin, a thrombin inhibitor, is still the drug of choice for preventing coagulation following, for example, cardiovascular surgery. On the contrary, much effort is done to evaluate the utilization of direct thrombin inhibitors to prevent ischemia/reperfusion injury. Furthermore, targeting the inflammatory potential of the coagulation system seems to be very promising. Fibrin(ogen) and its degradation products modulate the inflammatory response, especially by inducing leukocyte migration. Inhibiting these pro-inflammatory effects, for example, by administration of Bβ15-42 was recently shown to be beneficial under various inflammatory conditions.

SUMMARY

Ischemia and reperfusion are common activators of coagulation that is also accompanied by inflammation. Therefore, targeting this well orchestrated system might be of therapeutic benefit, as its mode of action is dual: clotting inhibition and anti-inflammation. This novel therapeutic approach might at least be of benefit in the treatment of systemic inflammatory syndromes following, that is, cardiovascular surgery.