Shiga Toxin and Lipopolysaccharide Induce Platelet-Leukocyte Aggregates and Tissue Factor Release, a Thrombotic Mechanism in Hemolytic Uremic Syndrome

BACKGROUND: Aggregates formed between leukocytes and platelets in the circulation lead to release of tissue factor (TF)-bearing microparticles contributing to a prothrombotic state. As enterohemorrhagic Escherichia coli (EHEC) may cause hemolytic uremic syndrome (HUS), in which microthrombi cause tissue damage, this study investigated whether the interaction between blood cells and EHEC virulence factors Shiga toxin (Stx) and lipopolysaccharide (LPS) led to release of TF. METHODOLOGY/PRINCIPAL FINDINGS: The interaction between Stx or LPS and blood cells induced platelet-leukocyte aggregate formation and tissue factor (TF) release, as detected by flow cytometry in whole blood. O157LPS was more potent than other LPS serotypes. Aggregates formed mainly between monocytes and platelets and less so between neutrophils and platelets. Stimulated blood cells in complex expressed activation markers, and microparticles were released. Microparticles originated mainly from platelets and monocytes and expressed TF. TF-expressing microparticles, and functional TF in plasma, increased when blood cells were simultaneously exposed to the EHEC virulence factors and high shear stress. Stx and LPS in combination had a more pronounced effect on platelet-monocyte aggregate formation, and TF expression on these aggregates, than each virulence factor alone. Whole blood and plasma from HUS patients (n = 4) were analyzed. All patients had an increase in leukocyte-platelet aggregates, mainly between monocytes and platelets, on which TF was expressed during the acute phase of disease. Patients also exhibited an increase in microparticles, mainly originating from platelets and monocytes, bearing surface-bound TF, and functional TF was detected in their plasma. Blood cell aggregates, microparticles, and TF decreased upon recovery. CONCLUSIONS/SIGNIFICANCE: By triggering TF release in the circulation, Stx and LPS can induce a prothrombotic state contributing to the pathogenesis of HUS

Abnormalities on brain MR images during the course of familial haemophagocytic lymphohistocytosis in a child. A case report

PURPOSE: To describe and report the neuroradiological findings and clinical features in a patient with familial haemophagocytic lymphohistocytosis (FHL), a rare hereditary immune dysregulation in early childhood characterised by multisystem involvement, including in approximately 30% of cases also the central nervous system (CNS).MATERIAL AND METHODS: Serial brain MR examinations were carried out in a 4.5-year-old boy with FHL, finally complicated with Epstein-Barr virus (EBV)-driven posttransplantation lymphoma.RESULTS: Multiple brain MR examinations before and after contrast enhancement showed discrete perivascular non-enhancing areas of high signal intensity on T2 images, and later also an enhancing lesion in the right caudate nucleus.CONCLUSION: FHL should be included in the differential diagnosis of patchy white matter abnormalities in young patients. EBV-driven post-transplantation lymphoma, which may present as meningial and/or parenchymal CNS infiltration, is a differential diagnostic problem

Non-endocrine late complications in children after allogeneic haematopoietic SCT

Non-endocrine events represent a heterogeneous group of complications occurring in children who survive long term after haematopoietic SCT. This review highlights the late sequel in a growing child. The preparative regimen itself with high-dose chemotherapy and/or radiotherapy (TBI) or the treatment given before the transplant procedure may cause organ damage with permanent sequel. Immune reconstitution and chronic GvHD have crucial role in occurrence of clinical abnormalities and late severe infections. Autoimmune syndromes may occur after use of novel transplant modalities (cord blood transplantation, reduced intensity conditioning regimen and haploidentical T-cell-depleted SCTs). Exposure to chemo- and/or radiotherapy increases the risk of second malignant neoplasms. Surveillance strategy focusing on each potential complication risk at continuous follow-up will allow vigilant post transplant care. Each paediatrician must be well versed in appropriate monitoring of these complications. Guidelines and recommendations are provided for serious problems occurring at follow-up, which must rapidly be identified so that appropriate intervention can be initiated. To achieve cure at a lowest possible price in terms of suffering and cost expenditures for health care is an extended frontier of paediatric haematopoietic SCT and biggest challenge for a paediatrician

Endocrinological late complications after hematopoietic SCT in children

The main challenge for a pediatric hemato-oncologist today is to obtain a cure for the sick child with the minimum of treatment-related complications. Children on their way to achieving adulthood face many risks after hematopoietic SCT (HSCT). Continuous follow-up includes assessment of organ function, focus on vaccinations and screening for secondary malignancies. Updated treatment protocols are already adjusted according to the knowledge obtained on late effects, and the potential risks for complications are well balanced with expected benefits hopefully resulting in decreased potential risk for organ damage but still maintaining an unchanged or improved survival rate. Recent developments on pre-HSCT regimens, such as the introduction of new anticancer regimens and immunosuppressive agents will hopefully contribute to minimize the frequency and the severity of late complications. Knowledge about increased risk for long-term complications due to cancer therapy and pre-HSCT preparative regimens should encourage each caring physician to stick to follow-up protocols and treatment guidelines not only to improve the survival rate of transplanted children but also to improve their quality of life. To achieve adulthood by maintaining cognitive ability and psychosocial skills is the highest goal for an individual to become a competent member of a society. This review of late endocrine complications after HSCT focuses on growth, pubertal development, thyroid disorders and glucose metabolism in long-term survivors