Mechanisms underlying platelet function defect in a pedigree with familial platelet disorder with a predisposition to acute myelogenous leukemia: potential role for candidate RUNX1 targets.

BACKGROUND: Familial platelet disorder with a predisposition to acute myelogenous leukemia (FPD/AML) is an inherited platelet disorder caused by a germline RUNX1 mutation and characterized by thrombocytopenia, a platelet function defect, and leukemia predisposition. The mechanisms underlying FPD/AML platelet dysfunction remain incompletely clarified. We aimed to determine the contribution of platelet structural abnormalities and defective activation pathways to the platelet phenotype. In addition, by using a candidate gene approach, we sought to identify potential RUNX1-regulated genes involved in these defects. METHODS: Lumiaggregometry, α-granule and dense granule content and release, platelet ultrastructure, αIIb ß3 integrin activation and outside-in signaling were assessed in members of one FPD/AML pedigree. Expression levels of candidate genes were measured and luciferase reporter assays and chromatin immunoprecipitation were performed to study NF-E2 regulation by RUNX1. RESULTS: A severe decrease in platelet aggregation, defective αIIb ß3 integrin activation and combined αδ storage pool deficiency were found. However, whereas the number of dense granules was markedly reduced, α-granule content was heterogeneous. A trend towards decreased platelet spreading was found, and ß3 integrin phosphorylation was impaired, reflecting altered outside-in signaling. A decrease in the level of transcription factor p45 NF-E2 was shown in platelet RNA and lysates, and other deregulated genes included RAB27B and MYL9. RUNX1 was shown to bind to the NF-E2 promoter in primary megakaryocytes, and wild-type RUNX1, but not FPD/AML mutants, was able to activate NF-E2 expression. CONCLUSIONS: The FPD/AML platelet function defect represents a complex trait, and RUNX1 orchestrates platelet function by regulating diverse aspects of this process. This study highlights the RUNX1 target NF-E2 as part of the molecular network by which RUNX1 regulates platelet biogenesis and function.

Monocyte IL-2Ralpha expression is associated with thrombosis and the JAK2V617F mutation in myeloproliferative neoplasms.

The development of bone marrow fibrosis and thrombosis are main causes of morbidity in essential thrombocythemia (ET). Monocyte activation has been associated to the production of fibrosis-related cytokines and pro-thrombotic factors. The aim of this study was to identify new markers of monocyte activation in Phi-negative myeloproliferative neoplasms and to search for their relationship with clinical features. Forty-five patients comprising 30 ET, eight myelofibrosis and seven polycythemia vera were included. We evaluated the alpha subunit of IL-2 receptor (CD25) on monocytes, basal and LPS-induced IL-1beta release from mononuclear cells, and monocyte TGF-beta mRNA content. Patients who had thrombotic events displayed higher monocyte CD25 levels (6.2%) than those without symptoms (1.3%) and controls (2.6%), p=0.0006. JAK2V617F-positive patients had higher monocyte CD25 expression levels (4.7%), than JAK2V617F-negative (2.6%), p=0.0213. Patients with myeloproliferative neoplasms had similar monocyte CD25 expression than controls, both, in basal conditions and after cell adhesion. IL-1beta release and TGF-beta mRNA levels were normal. In conclusion, increased monocyte CD25 expression is associated with history of thrombosis and is also up-regulated in patients harboring JAK2V617F mutation. The finding of increased CD25 levels together with normal IL-1beta and TGF-beta production reveals a selective monocyte activation profile in myeloproliferative neoplasms.

HIV status, trust in health care providers, and distrust in the health care system among Bronx women.

Trust in health care providers and the health care system are essential. This study examined factors associated with trust in providers and distrust in the health care system among minority HIV-positive and -negative women. Interviews were conducted and laboratory tests performed with 102 women from the Women's Interagency HIV Study Bronx site. Interviews collected information about trust in providers, distrust in the system, substance use, mental health symptoms and medications, and sociodemographic characteristics. Many reported distrust of the health care system related to HIV, and most reported trust in their providers. On linear regression analyses, characteristics associated with distrust in the health care system included depressive symptoms (beta=0.48, p<0.05). Characteristics associated with trust in providers included HIV-positive status (beta=0.35, p<0.05), taking mental health medications (beta=0.39, p<0.05), and having a white provider (beta=0.36, p<0.05). Despite distrust in the health care system related to HIV, most reported high trust in their providers, with HIV-positive women trusting their providers more than HIV-negative women. Studies are needed to understand how trust in providers and the health care system is achieved and maintained, and how trust is correlated with HIV-related health outcomes.