CD144+ endothelial microparticles as a marker of endothelial injury in neonatal ABO blood group incompatibility.

BACKGROUND: ABO antigens are expressed on the surfaces of red blood cells and the vascular endothelium. We studied circulating endothelial microparticles (EMP) in ABO haemolytic disease of the newborn (ABO HDN) as a marker of endothelial activation to test a hypothesis of possible endothelial injury in neonates with ABO HDN, and its relation with the occurrence and severity of haemolysis. MATERIAL AND METHODS: Forty-five neonates with ABO HDN were compared with 20 neonates with Rhesus incompatibility (Rh HDN; haemolytic controls) and 20 healthy neonates with matched mother and infant blood groups (healthy controls). Laboratory investigations were done for markers of haemolysis and von Willebrand factor antigen (vWF Ag). EMP (CD144(+)) levels were measured before and after therapy (exchange transfusion and/or phototherapy). RESULTS: vWF Ag and pre-therapy EMP levels were higher in infants with ABO HDN or Rh HDN than in healthy controls, and were significantly higher in babies with ABO HDN than in those with Rh HDN (p<0.05). In ABO HDN, pre-therapy EMP levels were higher in patients with severe hyperbilirubinaemia than in those with mild and moderate disease or those with Rh HDN (p<0.001). Post-therapy EMP levels were lower than pre-therapy levels in both the ABO HDN and Rh HDN groups; however, the decline in EMP levels was particularly evident after exchange transfusion in ABO neonates with severe hyperbilirubinaemia (p<0.001). Multiple regression analysis revealed that the concentrations of haemoglobin, lactate dehydrogenase and indirect bilirubin were independently correlated with pre-therapy EMP levels in ABO HDN. DISCUSSION: Elevated EMP levels in ABO HDN may reflect an IgG-mediated endothelial injury parallel to the IgG-mediated erythrocyte destruction and could serve as a surrogate marker of vascular dysfunction and disease severity in neonates with this condition.

Flow cytometric assessment of circulating platelet and erythrocytes microparticles in young thalassemia major patients: relation to pulmonary hypertension and aortic wall stiffness.

Heart disease is the leading cause of mortality and morbidity in ß-thalassemia major (ß-TM). Aggregability of abnormal red cells and membrane-derived microparticles (MPs) stemming from activated platelets and erythrocytes are responsible for thrombotic risk. We measured platelet and erythrocyte MPs (PMPs and ErMPs) in 60 young ß-TM patients compared with 40 age- and sex-matched healthy controls and assessed their relation to clinicopathological characteristics and aortic elastic properties. Patients were studied stressing on transfusion history, splenectomy, thrombotic events, chelation therapy, hematological and coagulation profiles, flow cytometric measurement of PMPs (CD41b(+) ) and ErMPs (glycophorin A(+) ) as well as echocardiographic assessment of aortic elastic properties. Aortic stiffness index and pulmonary artery pressure were significantly higher, whereas aortic strain and distensibility were lower in TM patients than controls (P < 0.001). Both PMPs and ErMPs were significantly elevated in TM patients compared with controls, particularly patients with risk of pulmonary hypertension, history of thrombosis, splenectomy or serum ferritin >2500 µg/L (P < 0.001). Compliant patients on chelation therapy had lower MPs levels than non-compliant patients (P < 0.001). PMPs and ErMPs were positively correlated to markers of hemolysis, serum ferritin, D-dimer, vWF Ag, and aortic stiffness, whereas negatively correlated to hemoglobin level and aortic distensibility (P < 0.05). We suggest that increased MPs may be implicated in vascular dysfunction, pulmonary hypertension risk, and aortic wall stiffness observed in thalassemia patients. Their quantification could provide utility for early detection of cardiovascular abnormalities and monitoring the biological efficacy of chelation therapy.

Bone mass and biochemical markers of bone turnover in children and adolescents with chronic immune thrombocytopenia: relation to corticosteroid therapy and vitamin D receptor gene polymorphisms.

Optional drug therapy in refractory chronic immune thrombocytopenia (ITP) includes standard oral, pulsed high-dose steroid therapy, intravenous gamma globulin, anti-D, and immunosuppressive therapy or thrombopoietin receptor agonists. This work aimed to study the bone mass in children and adolescents with chronic ITP in relation to biochemical markers of bone turnover, cumulative steroid therapy, and the possible modulating effect of vitamin D receptor (VDR) gene polymorphisms. Thirty-six children and adolescents with chronic ITP were recruited from the Hematology Clinic, Children's Hospital, Ain Shams University and the Hematology Clinic of the National Research Centre in Egypt and compared with 43 healthy age- and sex-matched controls. The total cumulative dose of steroids was calculated. Bone markers (serum osteocalcin (OC) and propeptide I precollagen (PICP) and urinary deoxypyridinoline (DPD) excretion), analysis of VDR gene distribution, and dual energy X-ray absorptiometry at lumbar and hip regions were performed for patients and controls. Compared to controls, chronic ITP patients had higher body mass index (BMI) and lower height for age standard deviation score (SDS). Chronic ITP patients had lower levels of OC and C-terminal propeptide of type I procollagen (PICP) and higher urinary DPD excretion, and bone mineral density (BMD) was significantly lower for both spine and hip z-score (<0.001). BMD was inversely correlated with urinary DPD excretion, age, BMI, and cumulative steroid dose. There was significant negative correlation between cumulative oral steroid dose and BMD (r = -0.4, P = 0.01 and r = -0.45, p = 0.001 for spine and hip z-scores, respectively), but the correlation was non-significant in relation to cumulative pulsed steroid therapy. FokI polymorphism was significantly related to BMD for both spine and hip z-score (p = 0.015 and p = 0.008, respectively), but there was no relation between BMD and Bsm1 polymorphism. FokI gene polymorphism may be one of the contributing factors in bone loss in patients on chronic steroid therapy. High cumulative doses of corticosteroids increased bone resorption in young chronic ITP patients. Longitudinal studies are needed to confirm the effect of different steroid protocols on bone turnover. Protocols of therapy of chronic ITP should restrict corticosteroid use in growing children and favor alternative less harmful therapies.

Clinicopathological and radiological study of Egyptian ß-thalassemia intermedia and ß-thalassemia major patients: relation to complications and response to therapy.

The clinico epidemiological characteristics, frequency of complications, and response to various therapeutic modalities in 80 Egyptian ß-thalassemia intermedia (ß-TI) patients were compared with 70 ß-thalassemia major (ß-TM) patients. ß-Thalassemia intermedia patients had a higher incidence of left atrium dilatation, right ventricular dilatation and pulmonary hypertension, whereas, ß-TM patients showed a higher incidence of left ventricular (LV) dilatation, restrictive LV filling and impaired LV contractility, with an overall higher incidence of heart disease (p <0.001). Short stature, delayed puberty, osteoporosis, bone fractures, diabetes mellitus and viral hepatitis was frequently observed in ß-TM patients compared with ß-TI patients (p <0.05). Administration of hydroxyurea (HU) alone was associated with significant improvement in hematological parameters and quality of life for ß-TI patients. In conclusion, the risk of complications still burdens the life of Egyptian thalassemia patients and their frequency varies between ß-TI and ß-TM. We provide evidence that calls for the use of HU in ß-TI patients.