Circulating microparticles, protein C, free protein S and endothelial vascular markers in children with sickle cell anaemia

Abstract

IntroductionCirculating microparticles (MP) have been described in sickle cell anaemia (SCA); however, their interaction with endothelial markers remains unclear. We investigated the relationship between MP, protein C (PC), free protein S (PS), nitric oxide (NO), endothelin-1 (ET-1) and adrenomedullin (ADM) in a large cohort of paediatric patients.MethodA total of 111 children of African ethnicity with SCA: 51 in steady state; 15 in crises; 30 on hydroxyurea (HU) therapy; 15 on transfusion; 17 controls (HbAA) of similar age/ethnicity. MP were analysed by flow cytometry using: Annexin V (AV), CD61, CD42a, CD62P, CD235a, CD14, CD142 (tissue factor), CD201 (endothelial PC receptor), CD62E, CD36 (TSP-1), CD47 (TSP-1 receptor), CD31 (PECAM), CD144 (VE-cadherin). Protein C, free PS, NO, pro-ADM and C-terminal ET-1 were also measured.ResultsTotal MP AV was lower in crisis (1.26×106 ml−1; 0.56–2.44×106) and steady state (1.35×106 ml−1; 0.71–3.0×106) compared to transfusion (4.33×106 ml−1; 1.6–9.2×106, p<0.01). Protein C levels were significantly lower in crisis (median 0.52 IU ml−1; interquartile range 0.43–0.62) compared with all other groups: HbAA (0.72 IU ml−1; 0.66–0.82, p<0.001); HU (0.67 IU ml−1; 0.58–0.77, p<0.001); steady state (0.63 IU ml−1; 0.54–0.70, p<0.05) and transfusion (0.60 IU ml−1; 0.54–0.70, p<0.05). In addition, levels were significantly reduced in steady state (0.63 IU ml−1; 0.54–0.70) compared with HbAA (0.72 IU ml−1; 0.66–0.80, p<0.01). PS levels were significantly higher in HbAA (0.85 IU ml−1; 0.72–0.97) compared with crisis (0.49 IU ml−1; 0.42–0.64, p<0.001), HU (0.65 IU ml−1; 0.56–0.74, p<0.01) and transfusion (0.59 IU ml−1; 0.47–0.71, p<0.01). There was also a significant difference in crisis patients compared with steady state (0.49 IU ml−1; 0.42–0.64 vs. 0.68 IU ml−1; 0.58–0.79, p<0.05). There was high correlation (R>0.9, p<0.05) between total numbers of AV-positive MP (MP AV) and platelet MP expressing non-activation platelet markers. There was a lower correlation between MP AV and MP CD62P (R=0.73, p<0.05) (platelet activation marker), and also a lower correlation between percentage of MP expressing CD201 (%MP CD201) and %MP CD14 (R=0.627, p<0.001). %MP CD201 was higher in crisis (11.6%) compared with HbAA (3.2%, p<0.05); %MP CD144 was higher in crisis (7.6%) compared with transfusion (2.1%, p<0.05); %CD14 (0.77%) was higher in crisis compared with transfusion (0.0%, p<0.05) and steady state (0.0%, p<0.01); MP CD14 was detectable in a higher number of samples (92%) in crisis compared with the rest (40%); %MP CD235a was higher in crisis (17.9%) compared with transfusion (8.9%), HU (8.7%) and steady state (9.9%, p<0.05); %CD62E did not differ significantly across the groups and CD142 was undetectable. Pro-ADM levels were raised in chest crisis: 0.38 nmol L−1 (0.31–0.49) versus steady state: 0.27 nmol L−1 (0.25–0.32; p<0.01) and control: 0.28 nmol L−1 (0.27–0.31; p<0.01). CT-proET-1 levels were reduced in patients on HU therapy: 43.6 pmol L−1 (12.6–49.6) versus control: 55.1 pmol L−1 (45.2–63....

Oxidative stress and phosphatidylserine exposure in red cells from patients with sickle cell anaemia

“…From these observations, it is unlikely that the observed reduction in PS measurements in the presence of oxidants was due to an overall loss of PS through oxidant‐induced shedding into the extracellular media, excluding red cells as a possible source of PS‐containing microvesicles in response to oxidant challenge (Piccin et al , 2007; Piccin et al , 2015a) although they may participate in Ca 2+ ‐induced PS loss.…”

“…PS may be lost as microvesicles, which have been proposed as a biomarker for SCA severity (Piccin et al , 2015a). Total thrombin formation in permeabilised red cells (using hypotonic lysis) were similar in controls and after oxidant challenge, however, which makes it unlikely that large reductions in labelled PS on the outer bilayer (up to 65%) could result from PS shedding.…”

“…Furthermore, PS may be expelled as microvesicles. The involvement of these particles in the pathogenesis of SCA and other conditions has been widely postulated (Piccin et al , 2007, 2015a, 2017; Nebor et al , 2014). …”

Severe non-exertional rhabdomyolysis from weight loss supplement in sickle cell trait: A perfect storm?

“…Systemic micro-particles, proteins C and S, endothelin-1 (ET-1), thrombin-antithrombin (TAT) complexes, prothrombin fragment 1.2 (F1.2), absolute blood monocyte levels and adrenomedullin (ADM) have been described as markers of hypercoagulable states in sickle cell disease. [20][21][22] The intensity of anticoagulation using these markers as measures is significantly lesser in hemoglobin AS relative to SS. [22] Interestingly, rhabdomyolysis with concomitant renal failure has reportedly been associated with venous thromboembolism.…”

The Clinical Utility of Circulating Microparticles’ Measurement in Heart Failure Patients

“…Indeed, erythrocytes actively shed phospholipid-bound MPs [54]. MPs originating from erythrocytes are naturally produced in vivo during normal aging processes or they have associated with a variety of pathophysiological conditions including hematology diseases (hemolysis, sickle cell disease and thalassemia), chronic kidney disease (IgA nephropathy), uremia, stroke, acute infections, sepsis, trauma, thrombosis/embolia, allograft dysfunction [55][56][57][58][59][60]. Therefore, erythrocytes-derived MPs may secrete ex vivo during cold storage of RBCs [61].…”