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Published on: January 31, 2018
Studies of microparticles in patients with the antiphospholipid syndrome (APS)
A Vikerfors1, F Mobarrez, K Bremme
1Karolinska Institutet, Department of Medicine Solna, Unit of Rheumatology, Karolinska University Hospital, Stockholm, Sweden. anna.vikerfors@karolinska.se
Objectives:
To study circulating platelet, monocyte and endothelial microparticles (PMPs, MMPs and EMPs) in patients with antiphospholipid syndrome (APS) in comparison with healthy controls.
Material And Method:
Fifty-two patients with APS and 52 healthy controls were investigated. MPs were measured on a flow cytometer (Beckman Gallios) and defined as particles sized < 1.0 µm, negative to phalloidin, positive to lactadherin and positive to either CD42a (PMPs), CD144 (EMPs) or CD14 (MMPs). Exposure of CD142 (TF) was measured on CD144 positive MPs.
Results:
Total number of MPs (i.e. lactadherin positive particles) was higher in APS patients versus controls (p < 0.001). An increased number of EMPs (p < 0.001), increased TF-positive EMPs (p < 0.001) and increased MMPs (p < 0.001) were also observed. PMP numbers did not differ between the groups. None of the MP types differed in numbers between obstetric and thrombotic APS patients.
Conclusion:
We observed a high number of EMPs expressing TF in APS patients. The numbers of MMPs and total EMPs were also higher as compared with healthy controls but in contrast to previous reports, the number of PMPs did not differ between groups.
Insights
Antiphospholipid syndrome (APS) patients show elevated levels of endothelial microparticles (EMPs) and monocyte microparticles (MMPs), with a significant increase in EMPs expressing tissue factor (TF). Platelet microparticle levels did not differ between APS patients and controls.
Area of Science:
- Immunology
- Hematology
- Cardiovascular Research
Background:
- Antiphospholipid syndrome (APS) is an autoimmune disorder associated with an increased risk of thrombosis and pregnancy complications.
- Microparticles (MPs) are small vesicles released from cell membranes, implicated in various pathological processes.
- Circulating MPs, including platelet microparticles (PMPs), monocyte microparticles (MMPs), and endothelial microparticles (EMPs), may serve as biomarkers in APS.
Purpose of the Study:
- To compare circulating PMPs, MMPs, and EMPs in patients with APS versus healthy controls.
- To investigate the expression of tissue factor (TF) on EMPs in APS patients.
- To determine if MP levels differ between obstetric and thrombotic APS subtypes.
Main Methods:
- Fifty-two APS patients and 52 healthy controls were enrolled.
- Microparticles were quantified using flow cytometry.
- MPs were identified as lactadherin-positive particles < 1.0 µm, with specific markers for PMPs (CD42a), EMPs (CD144), and MMPs (CD14). TF exposure (CD142) was measured on EMPs.
Main Results:
- Total MPs and EMPs were significantly higher in APS patients compared to controls (p < 0.001).
- TF-positive EMPs and MMPs were also significantly increased in APS patients (p < 0.001).
- PMP numbers did not differ between APS patients and controls, nor between APS subtypes.
Conclusions:
- APS patients exhibit elevated levels of EMPs and MMPs, with a notable increase in TF-expressing EMPs.
- The absence of difference in PMP levels contrasts with some previous findings.
- These microparticle profiles may offer insights into the pathophysiology of APS.
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