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␣-Hemoglobin-stabilizing protein (AHSP) is an erythroid protein that binds and stabilizes ␣-hemoglobin during normal erythropoiesis and in pathological states of ␣-hemoglobin excess. AHSP has been proposed as a candidate gene in some Heinz body hemolytic anemias and as a modifier gene in the ␤-thalassemia syndromes. To gain additional insight into the molecular mechanisms controlling the erythroid-specific expression of the AHSP gene and provide the necessary tools for further genetic studies of these disorders, we have initiated identification and characterization of the regulatory elements controlling the human AHSP gene. We mapped the 5-end of the AHSP erythroid cDNA and cloned the 5-flanking genomic DNA containing the putative AHSP gene promoter. In vitro studies using transfection of promoter/reporter plasmids in human tissue culture cell lines, DNase I footprinting analyses and gel mobility shift assays, identified an AHSP gene erythroid promoter with functionally important binding sites for GATA-1-and Oct-1-related proteins. In transgenic mice, a reporter gene directed by a minimal human AHSP promoter was expressed in bone marrow, spleen, and reticulocytes, but not in nonerythroid tissues. In vivo studies using chromatin immunoprecipitation assays demonstrated hyperacetylation of the promoter region and occupancy by GATA-1. The AHSP promoter is an excellent candidate region for mutations associated with decreased AHSP gene expression.␣-Hemoglobin-stabilizing protein (AHSP, 2 also known as erythroid differentiation-related factor, EDRF, and erythroid-associated factor, ERAF) is a recently identified erythroid protein that binds free ␣-hemoglobin and stabilizes it in solution and in cells (1-3). Interaction with AHSP inhibits reactive oxygen species production from ␣-hemoglobin and prevents the precipitation of highly unstable, cytotoxic free ␣-globin chains, which aggregate in erythroid precursors, damaging the membrane and triggering cell death (5). Thus AHSP is critical during normal erythropoiesis, where ␣-globin chain synthesis normally exceeds ␤-globin chain synthesis, and to a greater extent during pathologic states of globin chain imbalance.Because of its role in stabilizing ␣-globin, it has been suggested that AHSP may be a modifier gene in the ␤-thalassemia syndromes (1, 6). Decreased or defective AHSP would be expected to worsen the phenotype of ␤-thalassemia because of the cytotoxic effects of excessive free ␣-hemoglobin. In a murine model, AHSP deficiency leads to well-compensated hemolysis with Heinz body formation, reticulocytosis, and increased apoptosis of erythroid precursors (5). When AHSP-deficient mice were bred to ␤-thalassemia mice, loss of AHSP increased the severity of the thalassemia (5). These studies also suggested that AHSP might play a role in unexplained Heinz body hemolytic anemia in humans.Identification and characterization of the regulatory elements that control AHSP gene expression have important implications for normal erythropoiesis and the pathogenesis of hemolytic dis...

Comprehensive preclinical studies of Myelodysplastic Syndromes (MDS) have been elusive due to limited ability of MDS stem cells to engraft current immunodeficient murine hosts. Here we report a MDS patient-derived xenotransplantation model in cytokine-humanized immunodeficient “MISTRG” mice that provides efficient and faithful disease representation across all MDS subtypes. MISTRG MDS patient-derived xenografts (PDX) reproduce patients’ dysplastic morphology with multi-lineage representation, including erythro- and megakaryopoiesis. MISTRG MDS-PDX replicate the original sample’s genetic complexity and can be propagated via serial transplantation. MISTRG MDS-PDX demonstrate the cytotoxic and differentiation potential of targeted therapeutics providing superior readouts of drug mechanism of action and therapeutic efficacy. Physiologic humanization of the hematopoietic stem cell niche proves critical to MDS stem cell propagation and function in vivo. The MISTRG MDS-PDX model opens novel avenues of research and long-awaited opportunities in MDS research.

Bullous hemorrhagic dermatosis (BHD) is a systemic side-effect of low molecular weight heparin, characterized by multiple intra-epidermal hemorrhages distant from the site of injection. There have been several small case series and literature reviews on BHD, but none have captured a complete set of reported patients. We sought to describe a case of BHD with late diagnosis and completely summarize the existing English and Spanish literature with searches of Pubmed, Scopus, Ovid Embase and Ovid Medline. After narrowing to 33 relevant reports, we describe 90 reported cases worldwide from 2004 to 2017, in addition to a new case from our institution as a means of comparison. We found that BHD was common in elderly men (mean age 72 ± 12; male:female, 1.9:1) and typically occurred within 7 days of administration of anticoagulation (median 7 days ± 6.4) usually with enoxaparin use (66% of cases). Lesions occurred primarily on the extremities only (67.9% of cases). Coagulation testing was most often normal before administration, and the majority of patients had coagulation testing in therapeutic range during treatment. Most practitioners stopped anticoagulation if continued therapeutic intervention was no longer required (57% of cases), or changed therapy to another anticoagulation if continued treatment was required (14.3% of cases). Therapy was continued outright in 23% of patients. The lesions usually resolved within 2 weeks (mean days, 13.0 ± 7.4). There was no difference in time to resolution between patients who continued the culprit anticoagulant or changed to a different anticoagulant, and those who discontinued anticoagulation altogether (13.9 days vs. 12.1, p = 0.49). Four deaths have been reported in this clinical context, two specified as intracranial hemorrhage. These deaths were unrelated to the occurrence of BHD. Continuation of low-molecular weight heparins appeared to be safe in patients with BHD.

Tumor microenvironment (TME) is commonly implicated in regulating the growth of tumors, but whether it can directly alter the genetics of tumors is not known. IntroductionMultiple myeloma (MM) is characterized by the growth of malignant plasma cells in the BM. Genomic instability and chromosome translocations are common and early hallmarks of this tumor. 1 In particular, aneuploidy as well as chromosome translocations that involve the immunoglobulin heavy chain (IgH) locus are commonly observed in MM as well as its precursor monoclonal gammopathy of undetermined significance. However, the mechanisms underlying genomic instability in MM or monoclonal gammopathy of undetermined significance are poorly understood. One candidate is activation-induced cytidine deaminase (AID), which is essential for somatic hypermutation and class switch recombination. 2,3 Mistargeting of AID has been implicated in oncogenic mutations and chromosome translocations in both lymphoid and nonlymphoid tumors. [3][4][5] However, prior studies have failed to detect AID in MM cell lines, implying that other pathways may be involved in mediating genomic instability in this tumor. 6 Several studies have emphasized the importance of tumor microenvironment (TME) in the biology of human MM. 7 Although the role for TME in regulating tumor growth is well established, whether and how it might directly alter the genetics of tumors are not known. Several studies have shown that tumor lesions in MM are highly infiltrated by dendritic cells (DCs). [8][9][10] In prior studies we had observed that the interaction between DCs and MM cells led to aberrant reexpression of BCL6 in MM cells, a gene typically silenced during normal plasma cell differentiation. 11 Therefore, we tested whether this interaction could also induce the expression of AID in tumor cells. Methods Tumor cell lines and patient samplesMM cell lines were purchased from ATCC (U266), or kindly provided by Dr Joshua Epstein (Little Rock, AR; OPM2, ARK, and CAG cells). Other tumor cells used were MCF-7 cells (breast cancer; gift from Dr Lyndsay Harris, Yale Cancer Center). Cells were cultured in RPMI 1640 with 10%-15% FBS. BM and peripheral blood specimens were obtained from patients with myeloma after informed consent was obtained in accordance with the Declaration of Helsinki under a protocol approved by the institutional review board of Yale University. Peripheral blood buffy coats from healthy donors were purchased from the New York Blood Center. Isolation of mononuclear cells, DCs, primary tumor cells, and DC subsetsPeripheral blood or BM mononuclear cells (MNCs) were isolated by density gradient centrifugation (Ficoll-Paque plus; Amersham Biosciences). DCs were generated from purified blood monocytes as described earlier. 11,12 In brief, monocytes isolated with CD14 microbeads (Miltenyi Biotec) were cultured in the presence of GM-CSF (20 ng/mL; Genzyne) and IL-4 (20 ng/mL; R&D Systems). DCs were typically used on day 5 or 6 of culture. For some experiments, DCs were matured by the use of...