Statin use and bleeding risk during vitamin K antagonist treatment for venous thromboembolism: a multicenter retrospective cohort study

Shrinking Weibel-Palade bodies prevents high platelet recruitment in assays using thrombotic thrombocytopenic purpura plasma

BACKGROUND

Thrombotic thrombocytopenic purpura (TTP), caused by a genetic or autoimmune-driven lack of ADAMTS-13 activity, leads to high levels of the ultra-large von Willebrand factor (VWF) multimers produced by endothelial cells, causing excess platelet recruitment into forming thrombi, often with mortal consequences. Treatments include plasma infusion or replacement to restore ADAMTS-13 activity, or prevention of platelet recruitment to VWF.

OBJECTIVES

We tested a different approach, exploiting the unique cell biology of the endothelium. Upon activation, the VWF released by exocytosis of Weibel-Palade bodies (WPBs), transiently anchored to the cell surface, unfurls as strings into flowing plasma, recruiting platelets. Using plasma from patients with TTP increases platelet recruitment to the surface of cultured endothelial cells under flow. WPBs are uniquely plastic, and shortening WPBs dramatically reduces VWF string lengths and the recruitment of platelets. We wished to test whether the TTP plasma-driven increase in platelet recruitment would be countered by reducing formation of the longest WPBs that release longer strings.

METHODS

Endothelial cells grown in flow chambers were treated with fluvastatin, one of 37 drugs shown to shorten WPBs, then activated under flow in the presence of platelets and plasma of either controls or patients with TTP.

RESULT

We found that the dramatic increase in platelet recruitment caused by TTP plasma is entirely countered by treatment with fluvastatin, shortening the WPBs.

CONCLUSIONS

This potential approach of ameliorating the endothelial contribution to thrombotic risk by intervening far upstream of hemostasis might prove a useful adjunct to more conventional and direct therapies.

Vitamin K Intake in Chronic Stroke: Implications for Dietary Recommendations

Previous research has identified a possible association between vitamin K intake and cardiometabolic disease. This could mean that the assessment of vitamin K intake is a meaningful tool when monitoring individuals with preexisting cardiovascular disease. Sixty chronic stroke survivors (men and women, body mass index (BMI) 30.36 ± 6.61 kg/m², age 61.7 ± 7.2 years) completed food records which were analyzed for energy, macronutrient, micronutrient, and food group servings. Participants were divided into two groups: below vitamin K recommendation (BEL, n = 49) and met vitamin K recommendation (MET, n = 11). Energy and macronutrient intake did not differ between groups (all p > 0.127). Vegetable intake was higher in the MET group (p = 0.0001). Vitamin K intake was higher in the MET group (p = 0.0001). Calcium (p = 0.003), vitamin A (p = 0.007), and vitamin E (p = 0.005) intakes were higher in the MET group. There were no differences in sodium, potassium, vitamin D, vitamin C, and iron intakes between groups (all p > 0.212). In this sample of chronic stroke survivors, 82% reported consuming below the Dietary Reference Intake (DRI) for vitamin K. Given that the majority of this study population did not reach the DRI for vitamin K, it is advisable to promote the adequate intake of food rich in vitamin K. Further work is needed to determine the significance of low vitamin K intake in this population.