Before reading a recent publication (JPGN 2013; 56: 401-07), I was not aware of microparticles; microparticles may play an important role in the development of venous thromboembolism (VTE). Pediatric patients with inflammatory bowel disease (IBD) have a higher relative risk of VTE compared to their peers than individuals >60 years of age, though the absolute risk is low. Much of the pathophysiology underlying the increased VTE risk remain uncertain.
Microparticles have been called “platelet dust” and are microvesicles that are released from the plasma membrane of many cells (leukocytes, red blood cells, endothelial cells, and platelets).
This study examined plasma samples from 33 pediatric patients with Crohn disease (CD), 20 pediatric patients with ulcerative colitis (UC), and 60 healthy controls. Subsequently, microparticles’ procoagulant activity was measured. The CD and UC patients were consecutively enrolled from the outpatient clinic. Only 3 patients in each IBD group was receiving a biologic therapy (infliximab). The disease activity and extent were compared with measures of procoagulant activity.
Several assays were undertaken to assess microparticles and thrombin generation. Key findings:
- Increased procoagulant function of microparticles was identified in all CD patients (active and quiescent) and in UC patients with active disease.
- A positive correlation was found between disease activity scores and procoagulant activity.
The authors note that elevated microparticles “may play a role in inflammation.” Inflammation and coagulation likely influence each other. The authors note that VTE risk is greatest during flares but is still increased in patients in remission compared with controls.
The authors do not discuss the relationship of mucosal healing to microparticles or VTE. However, given that clinical remission is not defined currently based on mucosal healing, it would be of interest to know the status of these microparticles and the risk of VTE with mucosal healing. Perhaps the “quiescent” CD patients have ongoing disease contributing to their increased risk of VTE and increased procoagulation function of microparticles.
Related blog entry:
**According to previous expert consensus guidelines, “routine heparin prophylaxis cannot be justified in children until better evidence is available to suggest that the benefit outweigh the risks” (Turner D, et al. Am J Gastroenterol 2011; 106: 574-88).
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