VEGF Regulation of Angiogenic Factors via Inflammatory Signaling in Myeloproliferative Neoplasms.

BACKGROUND: Chronic inflammation has been recognized in neoplastic disorders, including myeloproliferative neoplasm (MPN), as an important regulator of angiogenesis. AIMS: We investigated the influence of vascular endothelial growth factor (VEGF) and pro-inflammatory interleukin-6 (IL-6) on the expression of angiogenic factors, as well as inflammation-related signaling in mononuclear cells (MNC) of patients with MPN and JAK2V617F positive human erythroleukemic (HEL) cells. RESULTS: We found that IL-6 did not change the expression of angiogenic factors in the MNC of patients with MPN and HEL cells. However, IL-6 and the JAK1/2 inhibitor Ruxolitinib significantly increased angiogenic factors-endothelial nitric oxide synthase (eNOS), VEGF, and hypoxia-inducible factor-1 alpha (HIF-1α)-in patients with polycythemia vera (PV). Furthermore, VEGF significantly increased the expression of HIF-1α and eNOS genes, the latter inversely regulated by PI3K and mTOR signaling in the MNC of primary myelofibrosis (PMF). VEGF and inhibitors of inflammatory JAK1/2, PI3K, and mTOR signaling reduced the eNOS protein expression in HEL cells. VEGF also decreased the expression of eNOS and HIF-1α proteins in the MNC of PMF. In contrast, VEGF increased eNOS and HIF-1α protein expression in the MNC of patients with PV, which was mediated by the inflammatory signaling. VEGF increased the level of IL-6 immunopositive MNC of MPN. In summary, VEGF conversely regulated gene and protein expression of angiogenic factors in the MNC of PMF, while VEGF increased angiogenic factor expression in PV mediated by the inflammation-related signaling. CONCLUSION: The angiogenic VEGF induction of IL-6 supports chronic inflammation that, through positive feedback, further promotes angiogenesis with concomitant JAK1/2 inhibition.

IL6 inhibition of inflammatory S100A8/9 proteins is NF-κB mediated in essential thrombocythemia.

This study has been performed to determine the mechanism of activation of the myeloid related S100A proteins by inflammatory cytokines in myeloproliferative neoplasm (MPN). Besides microarray analysis of MPN-derived CD34+ cells, we analysed the pro-inflammatory IL6 and anti-inflammatory IL10 dependence of NF-κB, PI3K-AKT, and JAK-STAT signalling during induction of S100A proteins in mononuclear cells of MPN, by immunoblotting and flow cytometry. We observed the reduced gene expression linked to NF-κB and inflammation signalling in MPN-derived CD34+ cells. Both IL6 and IL10 reduced S100A8 and 100A9 protein levels mediated via NF-κB and PI3K signalling, respectively, in mononuclear cells of essential thrombocythemia (ET). We also determined the increased percentage of S100A8 and S100A9 positive granulocytes in ET and primary myelofibrosis, upgraded by the JAK2V617F mutant allele burden. S100A8/9 heterodimer induced JAK1/2-dependent mitotic arrest of the ET-derived granulocytes. SIGNIFICANCE OF THE STUDY: We demonstrated that inflammation reduced the myeloid related S100A8/9 proteins by negative feedback mechanism in ET. S100A8/9 can be a diagnostic marker of inflammation in MPN, supported by the concomitant NF-κB and JAK1/2 signalling inhibition in regulation of myeloproliferation and therapy of MPN.

IL-6 stimulation of DNA replication is JAK1/2 mediated in cross-talk with hyperactivated ERK1/2 signaling.

Myeloproliferative neoplasms (MPNs) are developing resistance to therapy by JAK1/2 inhibitor ruxolitinib. To explore the mechanism of ruxolitinib's limited effect, we examined the JAK1/2 mediated induction of proliferation related ERK1/2 and AKT signaling by proinflammatory interleukin-6 (IL-6) in MPN granulocytes and JAK2V617F mutated human erythroleukemia (HEL) cells. We found that JAK1/2 or JAK2 inhibition prevented the IL-6 activation of STAT3 and AKT pathways in polycythemia vera and HEL cells. Further, we showed that these inhibitors also blocked the IL-6 activation of the AKT pathway in primary myelofibrosis (PMF). Only JAK1/2 inhibitor ruxolitinib largely activated ERK1/2 signaling in essential thrombocythemia and PMF (up to 4.6 fold), with a more prominent activation in JAK2V617F positive granulocytes. Regarding a cell cycle, we found that IL-6 reduction of HEL cells percentage in G2M phase was reversed by ruxolitinib (2.6 fold). Moreover, ruxolitinib potentiated apoptosis of PMF granulocytes (1.6 fold). Regarding DNA replication, we found that ruxolitinib prevented the IL-6 augmentation of MPN granulocytes frequency in the S phase of the cell cycle (up to 2.9 fold). The inflammatory stimulation induces a cross-talk between the proliferation linked pathways, where JAK1/2 inhibition is compensated by the activation of the ERK1/2 pathway during IL-6 stimulation of DNA replication.

Oxidative and nitrosative stress in myeloproliferative neoplasms: the impact on the AKT / mTOR signaling pathway.

PURPOSE: A common feature of malignancies is increased reactive oxygen species (ROS) and reactive nitrogen species (RNS). We analyzed the influence of oxidative and nitrosative stress on the activation of AKT/mTOR signaling pathway in myeloproliferative neoplasms (MPN). METHODS: Oxidative stress-induced gene expression in circulatory CD34+ cells of MPN patients was studied by microarray analysis. Biomarkers of oxidative and nitrosative stress were determined using spectrophotometry in plasma and erythrocyte lysate. The levels of nitrotyrosine, inducible NO synthase (iNOS) and AKT/mTOR/p70S6K phosphorylation were determined by immunocytochemistry and immunoblotting in granulocytes of MPN patients. RESULTS: Antioxidants superoxide dismutase 2 (SOD2) and glutathione peroxidase 1 (GPx1) gene expression were increased in circulatory CD34+ cells, while SOD1 and GPx enzymes were reduced in the erythrocytes of MPN. Plasma malonyl-dialdehyde and protein carbonyl levels were elevated in MPN. The total antioxidant capacity in plasma and erythrocyte catalase (CT) activities was the most prominent in primary myelofibrosis (PMF) with JAK2V617F heterozygosity. The total nitrite/nitrate (NOx) level was augmented in the plasma of PMF patients (p<0.001), while nitrotyrosine and iNOS were generally increased in the granulocytes of MPN patients. Activation of AKT/mTOR signaling was the most significant in PMF (p<0.01), but demonstrated JAK2V617F dependence and consequent p70S6K phosphorylation in the granulocytes of essential thrombocytemia (ET) and polycythemia vera (PV) patients. Hydrogen peroxide stimulated mTOR pathway, iNOS and nitrotyrosine quantities, the last one prevented by the antioxidant n-acetyl-cysteine (NAC) in the granulocytes of MPN. CONCLUSION: Our study showed increased levels of oxidative and nitrosative stress parameters in MPN with JAK2V617F dependence. The ROS enhanced the constitutive activation of AKT/mTOR signaling and nitrosative parameters in MPN.

Angiogenic factors are increased in circulating granulocytes and CD34+ cells of myeloproliferative neoplasms.

It has been shown that angiogenesis and inflammation play an important role in development of most hematological malignancies including the myeloproliferative neoplasm (MPN). The aim of this study was to investigate and correlate the levels of key angiogenic molecules such as hypoxia-inducible factor-1α (HIF-1α), vascular endothelial growth factor (VEGF) and endothelial nitric oxide synthase (eNOS) in peripheral blood and bone marrow cells of MPN patients, along with JAK2V617F mutation allele burden and effects of therapy. HIF-1α and VEGF gene expression were decreased, while eNOS mRNA levels were increased in granulocytes of MPN patients. Furthermore, positively correlated and increased VEGF and eNOS protein levels were in negative correlation with HIF-1α levels in granulocytes of MPN patients. According to immunoblotting, the generally augmented angiogenic factors demonstrated JAK2V617F allele burden dependence only in granulocytes of PMF. The angiogenic factors were largely reduced after hydroxyurea therapy in granulocytes of MPN patients. Levels of eNOS protein expression were stimulated by Calreticulin mutations in granulocytes of essential thrombocythemia. Immunocytochemical analyses of CD34+ cells showed a more pronounced enhancement of angiogenic factors than in granulocytes. Increased gene expression linked to the proinflammatory TGFß and MAPK signaling pathways were detected in CD34+ cells of MPN patients. In conclusion, the angiogenesis is increased in several cell types of MPN patients supported by the transcriptional activation of inflammation-related target genes, and is not limited to bone marrow stroma cells. It also appears that some of the benefit of hydroxyurea therapy of the MPN is mediated by effects on angiogenic factors. © 2016 Wiley Periodicals, Inc.

Bone marrow microvessel density and plasma angiogenic factors in myeloproliferative neoplasms: clinicopathological and molecular correlations.

Increased angiogenesis in BCR-ABL1 negative myeloproliferative neoplasms (MPNs) has been recognized, but its connection with clinical and molecular markers needs to be defined. The aims of study were to (1) assess bone marrow (BM) angiogenesis measured by microvessel density (MVD) using CD34 and CD105 antibodies; (2) analyze correlation of MVD with plasma angiogenic factors including vascular endothelial growth factor, basic fibroblast growth factor, and interleukin-8; (3) examine the association of MVD with clinicopathological and molecular markers. We examined 90 de novo MPN patients (30 polycythemia vera (PV), primary myelofibrosis (PMF), essential thrombocythemia (ET)) and 10 age-matched controls. MVD was analyzed by immunohistochemistry "hot spot" method, angiogenic factors by immunoassay and JAK2V617F, and CALR mutations by DNA sequencing and allelic PCR. MVD was significantly increased in MPNs compared to controls (PMF > PV > ET). Correlation between MVD and plasma angiogenic factors was found in MPNs. MVD was significantly increased in patients with JAK2V617F mutation and correlated with JAK2 mutant allele burden (CD34-MVD: ρ = 0.491, p < 0.001; CD105-MVD: ρ = 0.276, p = 0.02) but not with CALR mutation. MVD correlated with leukocyte count, serum lactate dehydrogenase, hepatomegaly, and splenomegaly. BM fibrosis was significantly associated with CD34-MVD, CD105-MVD, interleukin-8, and JAK2 mutant allele burden. JAK2 homozygote status had positive predictive value (100%) for BM fibrosis. Patients with prefibrotic PMF had significantly higher MVD than patients with ET, and we could recommend MVD to be additional histopathological marker to distinguish these two entities. This study also highlights the strong correlation of MVD with plasma angiogenic factors, JAK2 mutant allele burden, and BM fibrosis in MPNs.

Tuberous sclerosis complex protein 1 expression is affected by VHL Gene alterations and HIF-1α production in sporadic clear-cell renal cell carcinoma.

Alterations in von Hippel-Lindau gene (VHL) do not determine deregulation of hypoxia-inducible factors (HIFs) in clear-cell renal carcinoma (ccRCC). Their effects on tuberous sclerosis proteins (TSC1/2) and heat shock protein 90 (Hsp90) expressions in sporadic ccRCC are unknown. Therefore, we analyze the impact of VHL alterations and HIF-α production on the expression of TSC proteins and Hsp90 in these tumors. Alterations in VHL gene region exhibited 37/47 (78.7%) tumors. Monoallelic inactivation (intragenic mutation or LOH) was found in 10 (21.3%) and biallelic inactivation (intragenic mutation plus LOH) in 27 (57.4%) ccRCCs. Tumorous expression of HIF-α mRNAs, HIF-α, Hsp90 and TSC2 were VHL independent; TSC2 was underexpressed in all tumors by immunostaining (P<0.001). Immunoblotting revealed that TSC1 production was lower in tumors with monoallelic VHL inactivation than in control (P=0.01) and tissues with biallelic VHL inactivation (P=0.019), while tumors lacking HIF-1α (16/47) concurrently overexpressed HIF-2α and underexpressed TSC1 in comparison to controls (P=0.01 for both) and HIF-1α positive tumors (P=0.015 and P=0.050). Significant portion of variability (56.4%) in tumor diameter was explained by oscillations in nuclear grade, and TSC1 and HIF-2α expression in VHL altered tumors. In conclusion, while TSC2 is broadly downregulated in sporadic ccRCC, TSC1 expression is reduced in two subsets of these tumors, those with monoallelic VHL gene inactivation and those with concurrent low HIF-1α and high HIF-2α expression. Hence, the involvement of nuclear grade, TSC1 and HIF-2α in the progression of VHL altered tumors, implies the interplay between pVHL and TSC1.

Proinflammatory Cytokine IL-6 and JAK-STAT Signaling Pathway in Myeloproliferative Neoplasms.

The recent JAK1/2 inhibitor trial in myeloproliferative neoplasms (MPNs) showed that reducing inflammation can be more beneficial than targeting gene mutants. We evaluated the proinflammatory IL-6 cytokine and JAK-STAT signaling pathway related genes in circulating CD34(+) cells of MPNs. Regarding laboratory data, leukocytosis has been observed in polycythemia vera (PV) and JAK2V617F mutation positive versus negative primary myelofibrosis (PMF) patients. Moreover, thrombocytosis was reduced by JAK2V617F allele burden in essential thrombocythemia (ET) and PMF. 261 significantly changed genes have been detected in PV, 82 in ET, and 94 genes in PMF. The following JAK-STAT signaling pathway related genes had augmented expression in CD34(+) cells of MPNs: CCND3 and IL23A regardless of JAK2V617F allele burden; CSF3R, IL6ST, and STAT1/2 in ET and PV with JAK2V617F mutation; and AKT2, IFNGR2, PIM1, PTPN11, and STAT3 only in PV. STAT5A gene expression was generally reduced in MPNs. IL-6 cytokine levels were increased in plasma, as well as IL-6 protein levels in bone marrow stroma of MPNs, dependent on JAK2V617F mutation presence in ET and PMF patients. Therefore, the JAK2V617F mutant allele burden participated in inflammation biomarkers induction and related signaling pathways activation in MPNs.

The different effects of resveratrol and naringenin on isolated human umbilical vein: the role of ATP-sensitive K⁺ channels.

The blood flow from the placenta to the fetus depends on human umbilical vein (HUV) vascular tone. ATP-sensitive K(+) (K(ATP)) channels link the metabolic state of the cell to membrane potential, and their activation in the HUV represents protection against hypoxia. The aims of our study were to assess the effects of resveratrol and naringenin on the HUV and to define the roles of K(ATP) channels in their effects. Serotonin or 100 mM K(+) were used for precontraction of the HUV without endothelium. The cumulative concentration-response curves were obtained by adding increasing concentrations of resveratrol or naringenin. Glibenclamide was used, in order to test the role of K(ATP) channels in its effect. Resveratrol induced more potent vasodilatation of serotonin- and 100 mM K(+)-precontracted HUV than naringenin. Glibenclamide induced significant shift to the right of the concentration-response curves of resveratrol and P1075 (a specific opener of K(ATP) channels). Western blotting showed that HUV expressed protein Kir6.1. Thus, resveratrol and naringenin produce dilatation of HUV. It seems that K(ATP) channels are involved in the relaxation of HUV induced by resveratrol, while naringenin seems to interact with other ion channels. The K(+) channel-independent mechanism(s) of these polyphenols could not be excluded.

Transcriptional profiling of erythroid progenitors from G-CSF mobilized and nonmobilized peripheral blood.

PURPOSE: The purpose of this study was to examine the gene expression profile of granulocyte colony stimulating factor (G-CSF)-mobilized peripheral blood (mPB)-derived progenitors, used in transplantation. METHODS: We correlated gene expression patterns of highly enriched steady-state peripheral blood (PB)- and mPB-derived CD71+ cells by microarray and ingenuity pathway analyses, to identify the transcriptional program during in vitro erythroid differentiation. RESULTS: The gene expression was more than doubled in mPB-derived (4180 genes) compared to PB-derived erythroid progenitors (1667 genes) while PB-and mPB-derived erythroid progenitors shared 1534 common genes. Comparative analysis of transcript levels showed differential expression of 54 genes between cultured erythroid progenitors of PB and mPB origin, where we identified common 13 downregulated and 30 upregulated genes. The most significant genes in mPB-derived erythroid progenitors were P4HB, DDIA3, ARPC2 and ATP5G3. Regarding G-CSF stimulation the G-CSF receptor CSF2RB (1.1-fold) was linked via STAT3 to erythroid-specific ALAS2 (2.9-fold) and GATA2 (1.3-fold) factors, all upregulated in mPB-derived erythroid progenitors, coupled to common upregulated NUDC gene involved in the proliferation of erythroid cells. CONCLUSION: This report provides an extensive transcriptional profile of cultured erythroid progenitors and leads to a better understanding of diversity among the progenitor sources.

Effect of wine polyphenol resveratrol on the contractions elicited electrically or by norepinephrine in the rat portal vein.

We investigated the effects of resveratrol on rat portal vein (RPV) contractility without endothelium. Contractions were produced by electrical field stimulation of perivascular nerves (EFS), norepinephrine (NE), adenosine 5'-triphosphate (ATP), high K(+) solution and by calcium chloride (CaCl2 ) in Ca(2+) -free and high K(+) , Ca(2+) -free solution. The EFS-evoked contractions were more sensitive to resveratrol and to NS1619-selective openers of big calcium-sensitive (BKCa ) channels, than NE-evoked contractions. Effects of resveratrol on the ATP-evoked contractions were weak. Blockers of BKCa channels partly inhibited the effect of resveratrol only in EFS-contracted preparations. Western blotting showed that RPV expressed KCa 1.1 protein. Inhibitors of ATP- and voltage-sensitive K(+) channels did not modify the effects of resveratrol. None of the antagonists of K(+) channels affected the resveratrol inhibition of NE-evoked contractions and effect of high concentrations of resveratrol on the EFS-evoked contractions. Resveratrol more potently inhibited CaCl2 than potassium chloride contractions of RPV. Thus, BKCa channels partly mediate the inhibitory effect of resveratrol on the neurogenic contractions of RPV. The smooth muscle Ca(2+) channels and/or Ca(2+) mobilizing through cells might be involved in the effects of resveratrol on the contractility of RPV. Our results are important for better understanding the impact of resveratrol on the portal circulation.

Sex Differences and Cytokine Profiles among Patients Hospitalized for COVID-19 and during Their Recovery: The Predominance of Adhesion Molecules in Females and Oxidative Stress in Males.

The severity and mortality of coronavirus disease 2019 (COVID-19) are greater in males than in females, though the infection rate is the same in the two sexes. We investigated sex hormone differences associated with the hyperinflammatory immune response to SARS-CoV-2 on the basis of patients' cytokine profiles and vaccination statuses. Clinical and laboratory data of 117 patients with COVID-19 were collected to examine sex differences associated with oxidative stress markers, neutrophil extracellular traps (NETs), and plasma cytokine levels up to 5 months from hospital admission. The testosterone and free testosterone levels were low in male patients with COVID-19 and returned to normal values after recovery from the disease. The dihydrotestosterone (DHT) levels were transiently reduced, while the sex hormone-binding globulin levels were decreased in post-COVID-19 male patients. The levels of the inflammatory cytokines interleukin-6 (IL-6) and IL-10 appeared generally increased at diagnosis and decreased in post-COVID-19 patients. In females, the concentration of tumor necrosis factor-alpha was increased by four times at diagnosis. The levels of the coagulation markers intercellular adhesion molecule-1 (ICAM-1) and E-selectin were consistently upregulated in post-COVID-19 female patients, in contrast to those of vascular cell adhesion molecule-1 (VCAM-1), P-selectin, and chemokine IL-8. DHT increased the levels of reactive oxygen species in the neutrophils of male patients, while estradiol decreased them in females. Markers for NET, such as circulating DNA and myeloperoxidase, were significantly more abundant in the patients' plasma. Sex hormones have a potential protective role during SARS-CoV-2 infection, which is weakened by impaired testosterone synthesis in men.

JAK-STAT and AKT pathway-coupled genes in erythroid progenitor cells through ontogeny.

BACKGROUND: It has been reported that the phosphatidylinositol 3-kinase (PI3K)-AKT signaling pathway regulates erythropoietin (EPO)-induced survival, proliferation, and maturation of early erythroid progenitors. Erythroid cell proliferation and survival have also been related to activation of the JAK-STAT pathway. The goal of this study was to observe the function of EPO activation of JAK-STAT and PI3K/AKT pathways in the development of erythroid progenitors from hematopoietic CD34+ progenitor cells, as well as to distinguish early EPO target genes in human erythroid progenitors during ontogeny. METHODS: Hematopoietic CD34+ progenitor cells, isolated from fetal and adult hematopoietic tissues, were differentiated into erythroid progenitor cells. We have used microarray analysis to examine JAK-STAT and PI3K/AKT related genes, as well as broad gene expression modulation in these human erythroid progenitor cells. RESULTS: In microarray studies, a total of 1755 genes were expressed in fetal liver, 3844 in cord blood, 1770 in adult bone marrow, and 1325 genes in peripheral blood-derived erythroid progenitor cells. The erythroid progenitor cells shared 1011 common genes. Using the Ingenuity Pathways Analysis software, we evaluated the network pathways of genes linked to hematological system development, cellular growth and proliferation. The KITLG, EPO, GATA1, PIM1 and STAT3 genes represent the major connection points in the hematological system development linked genes. Some JAK-STAT signaling pathway-linked genes were steadily upregulated throughout ontogeny (PIM1, SOCS2, MYC, PTPN11), while others were downregulated (PTPN6, PIAS, SPRED2). In addition, some JAK-STAT pathway related genes are differentially expressed only in some stages of ontogeny (STATs, GRB2, CREBB). Beside the continuously upregulated (AKT1, PPP2CA, CHUK, NFKB1) and downregulated (FOXO1, PDPK1, PIK3CG) genes in the PI3K-AKT signaling pathway, we also observed intermittently regulated gene expression (NFKBIA, YWHAH). CONCLUSIONS: This broad overview of gene expression in erythropoiesis revealed transcription factors differentially expressed in some stages of ontogenesis. Finally, our results show that EPO-mediated proliferation and survival of erythroid progenitors occurs mainly through modulation of JAK-STAT pathway associated STATs, GRB2 and PIK3 genes, as well as AKT pathway-coupled NFKBIA and YWHAH genes.

Correlation between leukocyte-platelet aggregates and thrombosis in myeloproliferative neoplasms.

INTRODUCTION: The impact of activated blood and endothelial cells on the thrombosis in myeloproliferative neoplasms (MPN) has not yet been clarified. We prospectively analyzed correlation between circulating leukocyte-platelet aggregates and soluble selectins to thrombosis occurrence in MPN, in the context of standard and cardiovascular risk factors, and different clinical and biological characteristics. METHODS: Flow cytometric analysis of neutrophil-platelet (Neu-Plt) and monocyte-platelet (Mo-Plt) aggregates in peripheral blood, as well as quantification of soluble E-/L-/P-selectins by enzyme immunoassay, was performed on 95 newly diagnosed MPN patients. RESULTS: During the follow-up, thrombosis occurred in 12.6% MPN patients (arterial 9.4%, venous 3.2%), with a mean time of 39 months. The overall incidence rate of main thrombotic events was 4.36 per 100 patient-years. The incidence of arterial hypertension (HTA) was significantly higher in patients with thrombosis, compared to those without thrombosis (P < .05). The level of soluble P-selectin was significantly higher in patients with thrombosis compared to those without thrombosis (346.89 ng/mL vs 286.39 ng/mL, P = .034). The mean level of Neu-Plt (26.7% vs 22.4%) and Mo-Plt (17.8% vs 12.3%) aggregates did not differ significantly between the groups with and without thrombosis. A multivariate COX proportional hazard regression model confirmed an independent predictive significance of Mo-Plt aggregates (HR = 1.561, 95% CI: 1.007-2.420, P = .046), as well as the cumulative effect of Mo-Plt aggregates and HTA (HR = 1.975, 95%CI: 1.215-3.212, P = .006) for thrombosis occurrence. CONCLUSION: Monocyte-platelet aggregates represent an independent risk factor for thrombosis occurrence, further on supported by HTA.

Inhibition of proinflammatory signaling impairs fibrosis of bone marrow mesenchymal stromal cells in myeloproliferative neoplasms.

Although bone marrow-derived mesenchymal stromal cells (BM-MSCs) have been identified as a major cellular source of fibrosis, the exact molecular mechanism and signaling pathways involved have not been identified thus far. Here, we show that BM-MSCs contribute to fibrosis in myeloproliferative neoplasms (MPNs) by differentiating into αSMA-positive myofibroblasts. These cells display a dysregulated extracellular matrix with increased FN1 production and secretion of profibrotic MMP9 compared to healthy donor cells. Fibrogenic TGFß and inflammatory JAK2/STAT3 and NFκB signaling pathway activity is increased in BM-MSCs of MPN patients. Moreover, coculture with mononuclear cells from MPN patients was sufficient to induce fibrosis in healthy BM-MSCs. Inhibition of JAK1/2, SMAD3 or NFκB significantly reduced the fibrotic phenotype of MPN BM-MSCs and was able to prevent the development of fibrosis induced by coculture of healthy BM-MSCs and MPN mononuclear cells with overly active JAK/STAT signaling, underlining their involvement in fibrosis. Combined treatment with JAK1/2 and SMAD3 inhibitors showed synergistic and the most favorable effects on αSMA and FN1 expression in BM-MSCs. These results support the combined inhibition of TGFß and inflammatory signaling to extenuate fibrosis in MPN.

Erythropoietin and hypoxia increase erythropoietin receptor and nitric oxide levels in lung microvascular endothelial cells.

Acute lung exposure to low oxygen results in pulmonary vasoconstriction and redistribution of blood flow. We used human microvascular endothelial cells from lung (HMVEC-L) to study the acute response to oxygen stress. We observed that hypoxia and erythropoietin (EPO) increased erythropoietin receptor (EPOR) gene expression and protein level in HMVEC-L. In addition, EPO dose- and time-dependently stimulated nitric oxide (NO) production. This NO stimulation was evident despite hypoxia induced reduction of endothelial NO synthase (eNOS) gene expression. Western blot of phospho-eNOS (serine1177) and eNOS and was significantly induced by hypoxia but not after EPO treatment. However, iNOS increased at hypoxia and with EPO stimulation compared to normal oxygen tension. In accordance with our previous results of NO induction by EPO at low oxygen tension in human umbilical vein endothelial cells and bone marrow endothelial cells, these results provide further evidence in HMVEC-L for EPO regulation of NO production to modify the effects of hypoxia and cause compensatory vasoconstriction.

The effects of potassium channel opener P1075 on the human saphenous vein and human internal mammary artery.

Because adrenergic contractions can contribute to the development of life-threatening spasm of coronary artery bypass graft, this study was performed to investigate the effect of adenosine 3-phosphate (ATP)-sensitive K channel (KATP) opener P1075 on contractions of isolated human saphenous vein (HSV) and human internal mammary artery (HIMA). Phasic contractions were evoked by electric field stimulation (20 Hz) and noradrenaline. The sustained contractions were evoked by phenylephrine. The presence of pore-forming Kir6.1 and Kir6.2 subunits of the KATP channels in the HIMA and only Kir6.2 in the HSV was confirmed immunomorphologically. P1075 inhibited in the HSV only, the electrical field stimulation contractions more strongly than noradrenaline contractions. In addition, the phenylephrine contractions of HSV were more sensitive to P1075 in comparison to those of HIMA. Glibenclamide, a KATP channel blocker antagonized the vasodilatation produced by P1075 in both grafts differently, because its effect was more prominent on the P1075-induced inhibition of contractions of HSV than of HIMA. We conclude that P1075 has a vasorelaxant effect and inhibited adrenergic contractions of the tested grafts. This effect is graft and vasoconstrictor selective and seems to be mediated by Kir6.1- and/or Kir6.2-containing KATP channels. Thus, P1075 can be considered as a potential drug in the prevention of graft spasm.

ARMC5 Alterations in Patients With Sporadic Neuroendocrine Tumors and Multiple Endocrine Neoplasia Type 1 (MEN1).

CONTEXT: Adrenal lesions are frequent among patients with sporadic neuroendocrine tumors (spNETs) or multiple endocrine neoplasia type 1 (MEN1). Armadillo repeat-containing 5 (ARMC5)-inactivating variants cause adrenal tumors and possibly other neoplasms. OBJECTIVE: The objective of this work is to investigate a large cohort spNETs or MEN1 patients for changes in the ARMC5 gene. PATIENTS AND METHODS: A total of 111 patients, 94 with spNET and 17 with MEN1, were screened for ARMC5 germline alterations. Thirty-six tumors (18 spNETs and 18 MEN1 related) were collected from 20 patients. Blood and tumor DNA samples were genotyped using Sanger sequencing and microsatellite markers for chromosomes. ARMC5 and MEN1 expression were assessed by immunohistochemistry. RESULTS: In 76 of 111 (68.4%) patients, we identified 16 different ARMC5 germline variants, 2 predicted as damaging. There were no differences in the prevalence of ARMC5 variants depending on the presence of MEN1-related adrenal lesions. Loss of heterozygosity (LOH) at chromosome 16p and ARMC5 germline variants were present together in 23 or 34 (67.6%) tumors; in 7 of 23 (30.4%) their presence led to biallelic inactivation of the ARMC5 gene. The latter was more prevalent in MEN1-related tumors than in spNETs (88.9% vs 38.9%; P = .005). LOH at the chromosome 16p (ARMC5) and 11q (MEN1) loci coexisted in 16/18 MEN1-related tumors, which also expressed lower ARMC5 (P = .02) and MEN1 (P = .01) proteins compared to peritumorous tissues. CONCLUSION: Germline ARMC5 variants are common among spNET and MEN1 patients. ARMC5 haploinsufficiency or biallelic inactivation in spNETs and MEN1-related tumors suggests that ARMC5 may have a role in modifying the phenotype of patients with spNETs and/or MEN1 beyond its known role in macronodular adrenocortical hyperplasia.

TLR4 and RAGE conversely mediate pro-inflammatory S100A8/9-mediated inhibition of proliferation-linked signaling in myeloproliferative neoplasms.

PURPOSE: Previously, the family of S100A proteins has been found to be associated with inflammation and myelopoiesis and to be able to induce or support myeloproliferation during chronic inflammation. Here, we studied the inflammatory myeloid-related proteins S100A4, S100A8, S100A9 and S100A12 in myeloproliferative neoplasms (MPNs) in order to assess the involvement of chronic inflammation in the pathogenesis of MPN. METHODS: We analyzed the S100A4, S100A8, S100A9 and S100A12 mRNA and protein levels in the bone marrow and circulation of 140 patients with MPN and 15 healthy controls using Western blotting, microarray-based mRNA expression profiling and ELISA assays, respectively. In addition we performed functional studies on the proliferation-related AKT and ERK1/2 signaling pathways in MPN-derived granulocytes using Western blotting and proteomic analyses. RESULTS: We found that the S100A mRNA levels were increased in MPN patient-derived circulatory CD34+ cells, and that their protein expression levels were also augmented in their granulocytes and bone marrow stroma cells, depending on the JAK2V617F mutation allele burden. We also found that calreticulin (CALR) mutations were related to reduced S100A8 plasma levels in primary myelofibrosis (PMF). The S100A8 plasma levels were found to be increased in MPN, the S100A9 plasma levels in PMF and essential thrombocythemia (ET), and the S100A12 plasma levels in polycythemia vera (PV). These S100A plasma levels showed a positive correlation with the systemic inflammation marker IL-8, as well as with the numbers of leukocytes and thrombocytes, depending on the JAK2V617F mutation status. Additionally, we found that heterodimeric S100A8/9 can inhibit the AKT pathway in MPN-derived granulocytes mediated by the Toll-like receptor 4 (TLR4), depending on the CALR mutation status. Conversely, we found that blocking of the receptor for advanced glycation end products (RAGE) increased the S100A8/9-mediated inhibition of AKT signaling in the MPN-derived granulocytes. Moreover, we found that heterodimeric S100A8/9 generally induced TLR4-mediated ERK1/2 dephosphorylation proportionally to the JAK2V617F mutation allele burden. TLR4/RAGE blocking prevented the S100A8/9-mediated inhibition of ERK1/2 phosphorylation in PV. CONCLUSIONS: From our data we conclude that the S100A8 and S100A9 granulocyte and plasma levels are increased in MPN patients, along with inflammation markers, depending on their JAK2V617F mutation allele burden. We also found that S100A8/9-mediated inhibition of the proliferation-related AKT and ERK1/2 signaling pathways can be decreased by CALR mutation-dependent TLR4 blocking and increased by RAGE inhibition in MPN.

Hydroxyurea induces fetal hemoglobin by the nitric oxide-dependent activation of soluble guanylyl cyclase.

Hydroxyurea treatment of patients with sickle-cell disease increases fetal hemoglobin (HbF), which reduces hemoglobin S polymerization and clinical complications. Despite its use in the treatment of myeloproliferative diseases for over 30 years, its mechanism of action remains uncertain. Recent studies have demonstrated that hydroxyurea generates the nitric oxide (NO) radical in vivo, and we therefore hypothesized that NO-donor properties might determine the hemoglobin phenotype. We treated both K562 erythroleukemic cells and human erythroid progenitor cells with S-nitrosocysteine (CysNO), an NO donor, and found similar dose- and time-dependent induction of gamma-globin mRNA and HbF protein as we observed with hydroxyurea. Both hydroxyurea and CysNO increased cGMP levels, and the guanylyl cyclase inhibitors ODQ, NS 2028, and LY 83,538 abolished both the hydroxyurea- and CysNO-induced gamma-globin expression. These data provide strong evidence for an NO-derived mechanism for HbF induction by hydroxyurea and suggest possibilities for therapies based on NO-releasing or -potentiating agents.