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Abstract: 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD) and polychlorinated biphenyls (PCBs) are persistent organic pollutants found as complex mixtures in the environment throughout the world. Therefore, humans are ubiquitously and simultaneously exposed to TCDD and PCBs. TCDD and PCBs alone have been linked to atherosclerosis. However, the effects of interactions or synergism between TCDD and PCBs on atherogenesis are unknown. We investigated the possible enhanced atherogenesis by co-exposure to TCDD and PCBs and the potential mechanism(s) involved in this enhancement. Male ApoE−/− mice were exposed to TCDD (15μg/kg) and Aroclor1254 (55mg/kg, a representative mixture of PCBs) alone or in combination by intraperitoneal injection four times over six weeks of duration. Our results showed that mice exposed to TCDD alone, but not Aroclor1254 alone, developed atherosclerotic lesions. Moreover, we found that atherosclerotic disease was exacerbated to the greatest extent in mice co-exposed to TCDD and Aroclor1254. The enhanced lesions correlated with several pro-atherogenic changes, including a marked increase in the accumulation of the platelet-derived chemokine PF4, and the expression of the proinflammatory cytokine MCP-1 and the critical immunity gene-RIG-I. Our data demonstrated that co-exposure to TCDD and Aroclor1254 markedly enhanced atherogenesis in ApoE−/− mice. Significantly, our observations suggest that combined exposure to TCDD and PCBs may be a greater cardiovascular health risk than previously anticipated from individual studies. [Copyright &y& Elsevier]

Abstract: A large body of evidence now demonstrates that angiostatic therapy represents a promising way to fight cancer. This research recently resulted in the approval of the first angiostatic agent for clinical treatment of cancer. Progress has been achieved in decrypting the cellular signaling in endothelial cells induced by angiostatic agents. These agents predominantly interfere with the molecular pathways involved in migration, proliferation and endothelial cell survival. In the current review, these pathways are discussed. A thorough understanding of the mechanism of action of angiostatic agents is required to develop efficient anti-tumor therapies. [Copyright &y& Elsevier]

Abstract: The transcription factor RUNX1 plays a crucial role in hematopoiesis. RUNX1 regulates both differentiation and proliferation of hematopoietic cells. Several reports have shown that RUNX1 participates in megakaryopoiesis, which is a process that leads to formation of platelets. However, to date, the mechanisms by which this occurs have not been fully elucidated. In the present study, we investigated whether siRNA-mediated depletion of RUNX1 affected megakaryopoiesis of UT-7/GM cells. The depletion of RUNX1 in UT-7/GM cells resulted in up-regulation of the expression of megakaryocytic markers and polyploidization, while cell proliferation was down-regulated. Furthermore, the overexpression of RUNX1 decreased the activity of megakaryocytic gene promoters. These results suggest that RUNX1 down-regulates terminal differentiation of megakaryocytes and promotes proliferation of megakaryocytic progenitors. [Copyright &y& Elsevier]

We have previously demonstrated that homeodomain proteins, MEIS1 and PBXs, transactivate the PF4 gene through the novel regulatory element termed TME. This study focuses on Pbx regulating protein 1 (PREP1), a MEIS1 homolog protein, for its transcriptional activity in the PF4 promoter. PREP1 binds to the TME in HEL cells. PREP1 was expressed in human megakaryocytes that differentiated from CD34+ cells. EMSA shows that either PREP1 by itself or PREP1/PBX complexes bind to the two TGACAG motifs in the TME and activate the PF4 promoter. Furthermore, PREP1 and PREP1/PBX complexes synergistically activate the PF4 promoter with GATA-1 and ETS-1. These data demonstrate that PREP1 is also an important transcription factor that regulates PF4 gene expression such as MEIS1. Additionally, these data imply functional similarities and differences between PREP1 and MEIS1 in the regulation of PF4 gene expression. [Copyright &y& Elsevier]

As the novel SARS-CoV-2 continues to infect numerous individuals worldwide, one of the leading approaches in dealing with the global health crisis is vaccination against the COVID-19. Due to recent reports, vaccination with ChAdOx1 nCov-19 (developed by Oxford and AstraZeneca) may result in a vaccine-induced catastrophic thrombotic thrombocytopenia disorder. Thus, as of March 16 of 2021, vaccination programs in 18 countries had been suspended until further examination, including Sweden, Germany and France. This disorder presents as extensive thrombosis in atypical sites, primarily in the cerebral venous, alongside thrombocytopenia and the production of autoantibody against platelet-factor 4 (PF4). PF4 autoantibody has the ability to binds the human FcRγIIA receptor of platelets and contribute to their aggregation. This rare adverse effect extremely resembles the clinical presentation of the classical immune-mediated HIT disorder, which occurs following exposure to heparin. Surprisingly, none of these patients had been pre-exposed to heparin before disease onset, leading to the hypothesis that a viral antigen from the vaccine had triggered the response. Importantly, COVID-19 had been associated with numerous autoimmune manifestations, including the production of pathogenic autoantibodies, new onset of autoimmune diseases and disorders. As the ChAdOx1 nCov-19 vaccination leads to the synthesis of specific SARS-CoV-2-proteins, they may trigger a production of PF4 autoantibody though molecular mimicry phenomena, while vaccination compounds lead to a rigorous bystander activation of immune cells. If existing, removing such homological sequences from the vaccine may eliminate this phenomenon. In contrast, it needs to be emphasized that the ChAdOx1 nCoV-19 vaccine was found to be safe and efficacious against symptomatic COVID-19 in randomized controlled trials, which included 23,848 participants from the UK, Brazil and South Africa. • Rare cases of ChAdOx1 nCov-19 vaccine-induced catastrophic thrombotic thrombocytopenia disorder had been documented. • The disorder presents as extensive thrombosis in atypical sites, alongside thrombocytopenia with PF4 autoantibody. • Molecular mimicry between human and components of SARS-CoV-2 might trigger the production of PF4 autoantibody. [ABSTRACT FROM AUTHOR]

Due to the variable overlap of multiple symptoms, accurate early diagnosis of NK/T-cell lymphoma-associated hemophagocytic syndrome (NK/T-LAHS) is difficult, making the prognosis extremely poor. Hemophagocytic syndrome (HPS) is now diagnosed primarily based on the hemophagocytic lymphohistiocytosis (HLH)-2004 diagnostic criteria, and platelet count is one of the baseline evaluations. However, in our study, the data showed that decreased platelets were not only a clinical feature of HPS but also the key cells that regulate inflammation by releasing α-granules containing upregulated platelet factor 4 (PF4) and downregulated platelet-derived growth factors (PDGFs). Furthermore, we found that angiopoietin-4 (ANG-4), which has significant differential expression, has been less reported, that may affect hematopoiesis and proinflammatory responses and can be used as diagnostic biomarkers together with PF4 and PDGFs. [ABSTRACT FROM AUTHOR]