Deskriptive Untersuchungen zur Erythropoese bei schwerer Malaria-Anämie

Die Malaria ist die Infektion mit der weltweit höchsten Morbidität und Mortalität und also die wichtigste parasitäre Erkrankung des Menschen. Malaria ist eine Protozoen-Infektion, die Erythrozyten befällt und durch die weibliche Anopheles-Mücke übertragen wird. Die mit der Malaria assoziierten Todesfälle sind fast ausnahmslos auf Infektionen mit Plasmodium falciparum zurückzuführen, das die sogenannte Malaria tropica auslöst. Eine der wichtigsten Komplikationen der Malaria tropica ist die schwere Malaria-Anämie, besonders bei Kindern im Alter bis sechs Jahre. Die Anämie ist aufgrund fehlender Transfusionsinfrastruktur oft nur schlecht behandelbar. In dieser Arbeit wurde bei 91 Kindern im Alter bis sechs Jahre die Erythropoese bei Malaria-Anämie untersucht. Auf der Ebene der Erythropoese lässt sich allerdings die Schwere der Anämie nicht allein erklären, sondern auch Erythrophagozytose und Hämolyse spielen eine wesentliche Rolle bei der Pathogenese der schweren Malaria-Anämie

Paeonol Oxime Inhibits bFGF-Induced Angiogenesis and Reduces VEGF Levels in Fibrosarcoma Cells

Background: We previously reported the anti-angiogenic activity of paeonol isolated from Moutan Cortex. In the present study, we investigated the negative effect of paeonol oxime (PO, a paeonol derivative) on basic fibroblast growth factor (bFGF)-mediated angiogenesis in human umbilical vein endothelial cells (HUVECs) (including tumor angiogenesis) and pro-survival activity in HT-1080 fibrosarcoma cell line. Methodology/Principal Findings: We showed that PO (IC50  = 17.3 µg/ml) significantly inhibited bFGF-induced cell proliferation, which was achieved with higher concentrations of paeonol (IC50 over 200 µg). The treatment with PO blocked bFGF-stimulated migration and in vitro capillary differentiation (tube formation) in a dose-dependent manner. Furthermore, PO was able to disrupt neovascularization in vivo. Interestingly, PO (25 µg/ml) decreased the cell viability of HT-1080 fibrosarcoma cells but not that of HUVECs. The treatment with PO at 12.5 µg/ml reduced the levels of phosphorylated AKT and VEGF expression (intracellular and extracelluar) in HT-1080 cells. Consistently, immunefluorescence imaging analysis revealed that PO treatment attenuated AKT phosphorylation in HT-1080 cells. Conclusions/Significance: Taken together, these results suggest that PO inhibits bFGF-induced angiogenesis in HUVECs and decreased the levels of PI3K, phospho-AKT and VEGF in HT-1080 cells

Hemolysis Is Associated with Low Reticulocyte Production Index and Predicts Blood Transfusion in Severe Malarial Anemia

Background: Falciparum Malaria, an infectious disease caused by the apicomplexan parasite Plasmodium falciparum, is among the leading causes of death and morbidity attributable to infectious diseases worldwide. In Gabon, Central Africa, one out of four inpatients have severe malarial anemia (SMA), a life-threatening complication if left untreated. Emerging drug resistant parasites might aggravate the situation. This case control study investigates biomarkers of enhanced hemolysis in hospitalized children with either SMA or mild malaria (MM). Methods and Findings: Ninety-one children were included, thereof 39 SMA patients. Strict inclusion criteria were chosen to exclude other causes of anemia. At diagnosis, erythrophagocytosis (a direct marker for extravascular hemolysis, EVH) was enhanced in SMA compared to MM patients (5.0 arbitrary units (AU) (interquartile range (IR): 2.2–9.6) vs. 2.1 AU (IR: 1.3–3.9), p<0.01). Furthermore, indirect markers for EVH, (i.e. serum neopterin levels, spleen size enlargement and monocyte pigment) were significantly increased in SMA patients. Markers for erythrocyte ageing, such as CD35 (complement receptor 1), CD55 (decay acceleration factor) and phosphatidylserine exposure (annexin-V-binding) were investigated by flow cytometry. In SMA patients, levels of CD35 and CD55 on the red blood cell surface were decreased and erythrocyte removal markers were increased when compared to MM or reconvalescent patients. Additionally, intravascular hemolysis (IVH) was quantified using several indirect markers (LDH, alpha-HBDH, haptoglobin and hemopexin), which all showed elevated IVH in SMA. The presence of both IVH and EVH predicted the need for blood transfusion during antimalarial treatment (odds ratio 61.5, 95% confidence interval (CI): 8.9–427). Interestingly, this subpopulation is characterized by a significantly lowered reticulocyte production index (RPI, p<0.05). Conclusions: Our results show the multifactorial pathophysiology of SMA, whereby EVH and IVH play a particularly important role. We propose a model where removal of infected and non-infected erythrocytes of all ages (including reticulocytes) by EVH and IVH is a main mechanism of SMA. Further studies are underway to investigate the mechanism and extent of reticulocyte removal to identify possible interventions to reduce the risk of SMA development

PRECLINICAL COMBINATION OF A NOVEL IRE1 RNASE INHIBITOR MKC-8866 AND TYROSINE KINASE INHIBITION ACTS SYNERGISTIC IN ACUTE LYMPHOBLASTIC LEUKEMIA

International audienceno abstrac

Osteopontin is a prognostic factor for survival of acute myeloid leukemia patients

Osteopontin (OPN) is a glycoprotein that is secreted by osteoblasts and hematopoietic cells. OPN suppresses the proliferation of hematopoietic stem cells in vitro and may regulate the hematopoietic stem cell pool. Increased serum OPN concentrations occur in chronic myeloid leukemia, multiple myeloma, and acute myeloid leukemia (AML). In the present study, we analyzed the prognostic impact of OPN in AML by investigating the expression and relevance of OPN in newly diagnosed AML patients from 2 large study groups (the German AML Cooperative Group and the Dutch-Belgian Hematology Oncology Cooperative group). IHC (n = 84), ELISAs of blood/BM sera (n = 41), and microarray data for mRNA levels (n = 261) were performed. Expression of OPN protein was increased in AML patients both in BM blasts (IHC) and in BM serum (ELISA) compared with healthy controls. Patients expressing high levels of OPN within the BM (IHC) experienced shortened overall survival (OS; P = .025). Multivariate analysis identified karyotype, blast clearance (day 16), and the level of OPN expression as independent prognostic factors for OS. This prompted us to analyze microarray data from 261 patients from a third cohort. The analysis confirmed OPN as a prognostic marker. In summary, high OPN mRNA expression indicated decreased event-free survival (P = .0002) and OS (P = .001). The prognostic role of OPN was most prominent in intermediate-risk AML. These data provide evidence that OPN expression is an independent prognostic factor in AML. (Blood. 2012; 119(22): 5215-5220

A tumour suppressor network relying on the polyamine-hypusine axis

Tumour suppressor genes encode a broad class of molecules whose mutational attenuation contributes to malignant progression. In the canonical situation, the tumour suppressor is completely inactivated through a two-hit process involving a point mutation in one allele and chromosomal deletion of the other. Here, to identify tumour suppressor genes in lymphoma, we screen a short hairpin RNA library targeting genes deleted in human lymphomas. We functionally identify those genes whose suppression promotes tumorigenesis in a mouse lymphoma model. Of the nine tumour suppressors we identified, eight correspond to genes occurring in three physically linked 'clusters', suggesting that the common occurrence of large chromosomal deletions in human tumours reflects selective pressure to attenuate multiple genes. Among the new tumour suppressors are adenosylmethionine decarboxylase 1 (AMD1) and eukaryotic translation initiation factor 5A (eIF5A), two genes associated with hypusine, a unique amino acid produced as a product of polyamine metabolism through a highly conserved pathway. Through a secondary screen surveying the impact of all polyamine enzymes on tumorigenesis, we establish the polyamine-hypusine axis as a new tumour suppressor network regulating apoptosis. Unexpectedly, heterozygous deletions encompassing AMD1 and eIF5A often occur together in human lymphomas and co-suppression of both genes promotes lymphomagenesis in mice. Thus, some tumour suppressor functions can be disabled through a two-step process targeting different genes acting in the same pathway

PTEN action in leukaemia dictated by the tissue microenvironment

PTEN encodes a lipid phosphatase that is underexpressed in many cancers owing to deletions, mutations or gene silencing. PTEN dephosphorylates phosphatidylinositol (3,4,5)-triphosphate, thereby opposing the activity of class I phosphatidylinositol 3-kinases that mediate growth- and survival-factor signalling through phosphatidylinositol 3-kinase effectors such as AKT and mTOR. To determine whether continued PTEN inactivation is required to maintain malignancy, here we generate an RNA interference-based transgenic mouse model that allows tetracycline-dependent regulation of PTEN in a time- and tissue-specific manner. Postnatal Pten knockdown in the haematopoietic compartment produced highly disseminated T-cell acute lymphoblastic leukaemia. Notably, reactivation of PTEN mainly reduced T-cell leukaemia dissemination but had little effect on tumour load in haematopoietic organs. Leukaemia infiltration into the intestine was dependent on CCR9 G-protein-coupled receptor signalling, which was amplified by PTEN loss. Our results suggest that in the absence of PTEN, G-protein-coupled receptors may have an unanticipated role in driving tumour growth and invasion in an unsupportive environment. They further reveal that the role of PTEN loss in tumour maintenance is not invariant and can be influenced by the tissue microenvironment, thereby producing a form of intratumoral heterogeneity that is independent of cancer genotype