Oral famotidine reduces the plasma level of soluble P-selectin in children with sickle cell disease

Plasma histamine levels are increased in patients with sickle cell disease (SCD), potentially promoting endothelial P-selectin expression and vaso-occlusion via histamine type 2 (H2) receptors. We conducted a prospective, non-comparative, single-centre study to determine whether famotidine, a H2 receptor antagonist, reduces P-selectin expression in SCD children. The median plasma P-selectin level was significantly reduced after 29 days of oral famotidine (53.2 ng/mL [IQR: 46.7-63.4] vs. 69.9 ng/mL [IQR: 53.6-84.2], median difference -10.2 ng/mL [IQR: -21.8 to -2.7], p = 0.005) in 28 patients. No effect was observed on other adhesion molecules, inflammation or haemolysis markers, except decreased reticulocyte count. No adverse events deemed related to famotidine were observed. Randomized controlled trials are now needed to assess the efficacy of famotidine in preventing vaso-occlusion in SCD.

Dramatic efficacy of cannabidiol on refractory chronic pain in an adolescent with sickle cell disease

Here, we report a dramatic efficacy of cannabidiol in an adolescent with SCD suffering from chronic pain refractory to other analgesics, with complete regression of chronic pain and rapid plasma histamine level normalization after treatment.

A deep dive into future therapies for microcytic anemias and clinical considerations

INTRODUCTION

Microcytic anemias (MA) have frequent or rare etiologies. New discoveries in understanding and treatment of microcytic anemias need to be reviewed.

AREAS COVERED

Microcytic anemias with a focus on most frequent causes and on monogenic diseases that are relevant for understanding biocellular mechanisms of MA. All treatments excepting gene therapy, with a focus on recent advances. Pubmed search with references selected by expert opinion.

EXPERT OPINION

As the genetic and cellular background of dyserythropoiesis will continue to be clarified, collaboration with bioengineering of treatments acting specifically at the protein domain level will continue to provide new therapies in haematology as well as oncology and neurology.

Mast cell-mediated inflammation relies on insulin-regulated aminopeptidase controlling cytokine export from the Golgi

BACKGROUND

On activation, mast cells rapidly release preformed inflammatory mediators from large cytoplasmic granules via regulated exocytosis. This acute degranulation is followed by a late activation phase involving synthesis and secretion of cytokines, growth factors, and other inflammatory molecules via the constitutive pathway that remains ill defined.

OBJECTIVE

We investigated the role for an insulin-responsive vesicle-like endosomal compartment, marked by insulin-regulated aminopeptidase (IRAP), in the secretion of TNF-α and IL-6 in mast cells and macrophages.

METHODS

Murine knockout (KO) mouse models (IRAP-KO and kit-W^sh/sh) were used to study inflammatory disease models and to measure and mechanistically investigate cytokine secretion and degranulation in bone marrow-derived mast cells in vitro.

RESULTS

IRAP-KO mice are protected from TNF-α-dependent kidney injury and inflammatory arthritis. In the absence of IRAP, TNF-α and IL-6 but not IL-10 fail to be efficiently secreted. Moreover, chemical targeting of IRAP endosomes reduced proinflammatory cytokine secretion. Mechanistically, impaired TNF-α export from the Golgi and reduced colocalization of vesicle-associated membrane protein (VAMP) 3-positive TNF-α transport vesicles with syntaxin 4 (aka Stx4) was observed in IRAP-KO mast cells, while VAMP8-dependent exocytosis of secretory granules was facilitated.

CONCLUSION

IRAP plays a novel role in mast cell-mediated inflammation through the regulation of exocytic trafficking of cytokines.

Long-Term Effects of Allogeneic Hematopoietic Stem Cell Transplantation on Systemic Inflammation in Sickle Cell Disease Patients

Allogeneic hematopoietic stem cell transplantation (allo-HSCT) is the only currently available curative treatment for sickle cell disease (SCD). However, the effects of HSCT on SCD pathophysiology are poorly elucidated. Here, we assessed red blood cell (RBC) adhesiveness, intensity of hemolysis, vascular tone markers and systemic inflammation, in SCD patients treated with allogeneic HSCT. Thirty-two SCD patients were evaluated before and on long-term follow-up after HSCT. Overall survival was 94% with no severe (grade III-IV) graft-vs-host disease and a 22% rejection rate (graft failure). Hematological parameters, reticulocyte counts, and levels of lactate dehydrogenase (LDH), endothelin-1 and VCAM-1 normalized in SCD patients post-HSCT. Expression of adhesion molecules on reticulocytes and RBC was lower in patients with sustained engraftment. Levels of IL-18, IL-15 and LDH were higher in patients that developed graft failure. Increased levels of plasma pro-inflammatory cytokines, mainly TNF-α, were found in SCD patients long-term after transplantation. SCD patients with sustained engraftment after allo-HSCT showed decreased reticulocyte counts and adhesiveness, diminished hemolysis, and lower levels of vascular tonus markers. Nevertheless, systemic inflammation persists for at least five years after transplantation, indicating that allo-HSCT does not equally affect all aspects of SCD pathophysiology.

XPO1 regulates erythroid differentiation and is a new target for the treatment of β-thalassemia

β-thalassemia major (β-TM) is an inherited hemoglobinopathy caused by a quantitative defect in the synthesis of β-globin chains of hemoglobin, leading to the accumulation of free a-globin chains that aggregate and cause ineffective erythropoiesis. We have previously demonstrated that terminal erythroid maturation requires a transient activation of caspase-3 and that the chaperone Heat Shock Protein 70 (HSP70) accumulates in the nucleus to protect GATA-1 transcription factor from caspase-3 cleavage. This nuclear accumulation of HSP70 is inhibited in human β-TM erythroblasts due to HSP70 sequestration in the cytoplasm by free a-globin chains, resulting in maturation arrest and apoptosis. Likewise, terminal maturation can be restored by transduction of a nuclear-targeted HSP70 mutant. Here we demonstrate that in normal erythroid progenitors, HSP70 localization is regulated by the exportin-1 (XPO1), and that treatment of β-thalassemic erythroblasts with an XPO1 inhibitor increased the amount of nuclear HSP70, rescued GATA-1 expression and improved terminal differentiation, thus representing a new therapeutic option to ameliorate ineffective erythropoiesis of β-TM.

Innate immune cells, major protagonists of sickle cell disease pathophysiology

Sickle cell disease (SCD), considered the most common monogenic disease worldwide, is a severe hemoglobin disorder. Although the genetic and molecular bases have long been characterized, the pathophysiology remains incompletely elucidated and therapeutic options are limited. It has been increasingly suggested that innate immune cells, including monocytes, neutrophils, invariant natural killer T cells, platelets and mast cells, have a role in promoting inflammation, adhesion and pain in SCD. Here we provide a thorough review of the involvement of these novel, major protagonists in SCD pathophysiology, highlighting recent evidence for innovative therapeutic perspectives.

Vitamin D Receptor Controls Cell Stemness in Acute Myeloid Leukemia and in Normal Bone Marrow

Vitamin D (VD) is a known differentiating agent, but the role of VD receptor (VDR) is still incompletely described in acute myeloid leukemia (AML), whose treatment is based mostly on antimitotic chemotherapy. Here, we present an unexpected role of VDR in normal hematopoiesis and in leukemogenesis. Limited VDR expression is associated with impaired myeloid progenitor differentiation and is a new prognostic factor in AML. In mice, the lack of Vdr results in increased numbers of hematopoietic and leukemia stem cells and quiescent hematopoietic stem cells. In addition, malignant transformation of Vdr-/- cells results in myeloid differentiation block and increases self-renewal. Vdr promoter is methylated in AML as in CD34+ cells, and demethylating agents induce VDR expression. Association of VDR agonists with hypomethylating agents promotes leukemia stem cell exhaustion and decreases tumor burden in AML mouse models. Thus, Vdr functions as a regulator of stem cell homeostasis and leukemic propagation.

Innate-like T cells in children with sickle cell disease

Background

The implication of lymphocytes in sickle cell disease pathogenesis is supported by a number of recent reports. These studies provided evidence for the activation of invariant natural killer T (iNKT) cells in adult patients, but did not investigate the involvement of other innate-like T cell subsets so far.

Methods

Here we present a monocentric prospective observational study evaluating the number and functional properties of both circulating conventional and innate-like T cells, namely iNKT, Mucosal-Associated Invariant T (MAIT) and gammadelta (γδ) T cells in a cohort of 39 children with sickle cell disease.

Results

Relative to age-matched healthy controls, we found that patients had a higher frequency of IL-13- and IL-17-producing CD4⁺ T cells, as well as higher MAIT cell counts with an increased frequency of IL-17-producing MAIT cells. Patients also presented increased Vδ2 γδ T cell counts, especially during vaso-occlusive crisis, and a lower frequency of IFNγ-producing Vδ2 γδ T cells, except during crisis. iNKT cell counts and the frequency of IFNγ-producing iNKT cells were unchanged compared to controls. Our study revealed positive correlations between 1) the frequency of IFNγ-producing CD4⁺, CD8⁺ and Vδ2 γδ T cells and the number of hospitalizations for vaso-occlusive crisis in the previous year; 2) the frequency of IFNγ-producing iNKT cells and patients’ age and 3) the frequency of IL-17-producing Vδ2 γδ T cells and hemoglobin S level.

Conclusion

These results strongly suggest a role of innate-like T cells in sickle cell disease pathophysiology, especially that of IL-17-producing MAIT and γδ T cells.

Lessons to Learn From Low-Dose Cyclosporin-A: A New Approach for Unexpected Clinical Applications

Cyclosporin-A has been known and used for a long time, since its "fast track" approval in the early 80's. This molecule has rapidly demonstrated unexpected immunosuppressive properties, transforming the history of organ transplantation. Cyclosporin's key effect relies on modulation on T-lymphocyte activity, which explains its role in the prevention of graft rejection. However, whether cyclosporin-A exerts other effects on immune system remains to be determined. Until recently, cyclosporin-A was mainly used at a high-dose, but given the drug toxicity and despite the fear of losing its immunosuppressive effects, there is nowadays a tendency to decrease its dose. The literature has been reporting data revealing a paradoxical effect of low dosage of cyclosporin-A. These low-doses appear to have immunomodulatory properties, with different effects from high-doses on CD8+ T lymphocyte activation, auto-immune diseases, graft-vs.-host disease and cancer. The aim of this review is to discuss the role of cyclosporin-A, not only as a consecrated immunosuppressive agent, but also as an immunomodulatory drug when administrated at low-dose. The use of low-dose cyclosporin-A may become a new therapeutic strategy, particularly to treat cancer.

High mTORC1 activity drives glycolysis addiction and sensitivity to G6PD inhibition in acute myeloid leukemia cells

Alterations in metabolic activities are cancer hallmarks that offer a wide range of new therapeutic opportunities. Here we decipher the interplay between mTORC1 activity and glucose metabolism in acute myeloid leukemia (AML). We show that mTORC1 signaling that is constantly overactivated in AML cells promotes glycolysis and leads to glucose addiction. The level of mTORC1 activity determines the sensitivity of AML cells to glycolysis inhibition as switch-off mTORC1 activity leads to glucose-independent cell survival that is sustained by an increase in mitochondrial oxidative phosphorylation. Metabolic analysis identified the pentose phosphate pathway (PPP) as an important pro-survival pathway for glucose metabolism in AML cells with high mTORC1 activity and provided a clear rational for targeting glucose-6-phosphate dehydrogenase (G6PD) in AML. Indeed, our analysis of the cancer genome atlas AML database pinpointed G6PD as a new biomarker in AML, as its overexpression correlated with an adverse prognosis in this cohort. Targeting the PPP using the G6PD inhibitor 6-aminonicotinamide induces in vitro and in vivo cytotoxicity against AML cells and synergistically sensitizes leukemic cells to chemotherapy. Our results demonstrate that high mTORC1 activity creates a specific vulnerability to G6PD inhibition that may work as a new AML therapy.

Abstract 4868: Tyrosine kinase-dependent modulation of tumor infiltrating immune cells in melanoma

Melanoma causes the greatest morbidity and mortality of all skin cancers and often harbors amplifications or activating mutations in KIT, a type III transmembrane receptor tyrosine kinase (RTK) involved in cancer cell growth, migration, invasion and metastasis. At present, no treatment that provide either sufficient response rates or a significant prolongation of overall survival are available for melanoma. In the last decade, several inhibitors of RTK (RTKi) have been developed for the treatment of cancer, however, a number of short-comings was observed. Therefore, novel TK inhibitors with improved selectivity were developed for the treatment of diseases associated with KIT activation. Masitinib (AB1010), a RTKi capable of blocking selectively KIT, is one such new drug. Using B16 melanoma subcutaneous graft on C57Bl6 mice, we demonstrate that Masitinib is able to limit tumor growth in vivo and increase mice survival. This anti-tumoral effect was not observed for other RTKi targeting KIT. Suprisingly, Masitinib has no effect on melanoma proliferation in vitro, suggesting instead that modulation on tumor environment takes place. Indeed, mast cells that accumulate in the tumors secrete several biologically active factors involved in the modulation of tumor growth. In vivo, Masitinib treatment completely abrogates mast cell maturation and migration resulting in decreased tumor invasion and down-regulation of several angiogenic factors. Using a mouse line deficient for mast cells (Wsh/Wsh), we confirmed that Masitinib effect is in part dependent of its inhibition on mast cell migration and maturation. Indeed, additional effect occurs on macrophage polarization leaning from “tolerogenic” toward “anti-tumoral” phenotype. Furthermore, in vivo macrophage depletion favored tumor promotion and reverses Masitinib effect on tumor growth. The results provided by this study suggest that Masitinib may be a useful therapy on melanoma by its dual role on tumor environment. It can block mast cell maturation and infiltration in the tumor site, avoiding the angiogenic effects of mast cells. It can revert tumor tolerent macrophage status leading to an increased inflammatory activity within the tumor microenvironment.

These effects are not observed only on melanoma, but also on other types of cancer, suggesting the cellular mechanisms triggered by Masitinib occur in various tumoral process. For instance, a phase III clinical trial with Masitinib as GIST treatment is currently ongoing.

Citation Format: Joël Babdor, Aurélie Fricot, Michaël Dussiot, Lucile Hebert, Patrice Dubreuil, Ivan Cruz Moura, Thiago Trovati Maciel, Olivier Hermine. Tyrosine kinase-dependent modulation of tumor infiltrating immune cells in melanoma. [abstract]. In: Proceedings of the 107th Annual Meeting of the American Association for Cancer Research; 2016 Apr 16-20; New Orleans, LA. Philadelphia (PA): AACR; Cancer Res 2016;76(14 Suppl):Abstract nr 4868.

HSP70 sequestration by free α-globin promotes ineffective erythropoiesis in β-thalassaemia

β-Thalassaemia major (β-TM) is an inherited haemoglobinopathy caused by a quantitative defect in the synthesis of β-globin chains of haemoglobin, leading to the accumulation of free α-globin chains that form toxic aggregates. Despite extensive knowledge of the molecular defects causing β-TM, little is known of the mechanisms responsible for the ineffective erythropoiesis observed in the condition, which is characterized by accelerated erythroid differentiation, maturation arrest and apoptosis at the polychromatophilic stage. We have previously demonstrated that normal human erythroid maturation requires a transient activation of caspase-3 at the later stages of maturation. Although erythroid transcription factor GATA-1, the master transcriptional factor of erythropoiesis, is a caspase-3 target, it is not cleaved during erythroid differentiation. We have shown that, in human erythroblasts, the chaperone heat shock protein70 (HSP70) is constitutively expressed and, at later stages of maturation, translocates into the nucleus and protects GATA-1 from caspase-3 cleavage. The primary role of this ubiquitous chaperone is to participate in the refolding of proteins denatured by cytoplasmic stress, thus preventing their aggregation. Here we show in vitro that during the maturation of human β-TM erythroblasts, HSP70 interacts directly with free α-globin chains. As a consequence, HSP70 is sequestrated in the cytoplasm and GATA-1 is no longer protected, resulting in end-stage maturation arrest and apoptosis. Transduction of a nuclear-targeted HSP70 mutant or a caspase-3-uncleavable GATA-1 mutant restores terminal maturation of β-TM erythroblasts, which may provide a rationale for new targeted therapies of β-TM.

Polymeric IgA1 controls erythroblast proliferation and accelerates erythropoiesis recovery in anemia

Anemia because of insufficient production of and/or response to erythropoietin (Epo) is a major complication of chronic kidney disease and cancer. The mechanisms modulating the sensitivity of erythroblasts to Epo remain poorly understood. We show that, when cultured with Epo at suboptimal concentrations, the growth and clonogenic potential of erythroblasts was rescued by transferrin receptor 1 (TfR1)-bound polymeric IgA1 (pIgA1). Under homeostatic conditions, erythroblast numbers were increased in mice expressing human IgA1 compared to control mice. Hypoxic stress of these mice led to increased amounts of pIgA1 and erythroblast expansion. Expression of human IgA1 or treatment of wild-type mice with the TfR1 ligands pIgA1 or iron-loaded transferrin (Fe-Tf) accelerated recovery from acute anemia. TfR1 engagement by either pIgA1 or Fe-Tf increased cell sensitivity to Epo by inducing activation of mitogen-activated protein kinase (MAPK) and phosphatidylinositol 3-kinase (PI3K) signaling pathways. These cellular responses were mediated through the TfR1-internalization motif, YXXΦ. Our results show that pIgA1 and TfR1 are positive regulators of erythropoiesis in both physiological and pathological situations. Targeting this pathway may provide alternate approaches to the treatment of ineffective erythropoiesis and anemia.

Disrupted cell cycle control in cultured endometrial cells from patients with endometriosis harboring the progesterone receptor polymorphism PROGINS

Presently, little is understood about how endometriosis is established or maintained, or how genetic factors can predispose women to the disease. Because of the crucial role that the progesterone receptor polymorphism PROGINS plays in predisposing women to the development of endometriosis, we hypothesized that this variant may influence critical steps during endometrial cell metabolism that are involved in the pathogenesis of endometriosis. Eutopic endometria were collected from three sources: women with endometriosis who had a single PROGINS allele (from the progesterone receptor gene); women with endometriosis who had the wild-type progesterone receptor allele; and women without endometriosis who had the wild-type allele. Cells prepared from the eutopic endometria of these women were stimulated with both estradiol and progesterone, and then examined for cell proliferation, viability, and apoptosis. The cells from women with endometriosis that carried the PROGINS allele demonstrated increased proliferation, greater viability, and decreased apoptosis following progesterone treatment. In general, these parameters were very different as compared with those of women with endometriosis but without the PROGINS allele and women in the control group. This result indicates there is a reduced level of progesterone responsiveness in women who carry the PROGINS polymorphism. Because progesterone responsiveness is known to be an important characteristic of women with endometriosis, these data support the contention that the PROGINS polymorphism enhances the endometriosis phenotype.

The bone morphogenetic protein antagonist gremlin promotes vascular smooth muscle cell apoptosis

BACKGROUND

Previous studies from our laboratory demonstrated that gremlin significantly increases vascular smooth muscle cell (VSMC) proliferation and migration. The present study investigates gremlin expression in the initial stages of rat carotid balloon injury and its effects on VSMC apoptosis.

METHODS

Gremlin mRNA expression was evaluated in rat carotids and cultured VSMCs by quantitative PCR. Apoptosis was analyzed in A7r5 cells and rabbit primary VSMCs following gremlin gene overexpression or silencing by chromatin morphology and caspase-3 activity.

RESULTS

Vascular injury promoted a significant decrease in gremlin mRNA levels. In addition, platelet-derived growth factor, angiotensin II and transforming growth factor (TGF)-beta1 promoted coordinated regulation of gremlin and bone morphogenetic protein (BMP)-4 expression in opposite directions according to the confluence status of VSMC culture. In A7r5 cells, gremlin overexpression was able to increase apoptosis, as demonstrated by chromatin morphology and caspase-3 activity, while BMP administration promoted opposite effects. Finally, in agreement with our results, gremlin gene silencing effectively suppressed apoptosis in A7r5 cells and rabbit VSMCs.

CONCLUSION

Gremlin is regulated by growth factors and vascular injury and is involved in modulation of VSMC apoptosis. Modifications of gremlin expression during vascular injury may contribute to the apoptosis resistance of VSMCs.

Escherichia coli lipopolysaccharide inhibits renin activity in human mesangial cells

Hyperactivation of systemic renin-angiotensin system (RAS) during sepsis is well documented. However, the behavior of intrarenal RAS in the context of endotoxemia is yet to be defined. The present study evaluates the direct effect of Escherichia coli lipopolysaccharide (LPS) on immortalized human mesangial cell (HMC) RAS. Quiescent HMC were incubated with vehicle or LPS (1-100 microg/ml), and levels of angiotensin I and II (Ang I and II) and their metabolites were analyzed by high-performance liquid chromatography. In addition, angiotensin-converting enzyme (ACE) and renin activity were also investigated. Cell lysate and extracellular medium levels of Ang II were rapidly reduced (1 h) in a time- and concentration-dependent manner, reaching a significant -9 fold-change (P<0.001) after 3 h of LPS incubation. Similar results were obtained for Ang I levels (-3 fold-change, P<0.001). We ruled out Ang I and II degradation, as levels of their metabolic fragments were also significantly decreased by LPS. ACE activity was slightly increased following LPS incubation. On the other hand, renin activity was significantly inhibited, as Ang I concentration elevation following exogenous angiotensinogen administration was blunted by LPS (-60% vs vehicle, P<0.001). Renin and angiotensinogen protein levels were not affected by LPS according to Western blot analysis. Taken together, these data demonstrate for the first time that LPS significantly downregulates HMC RAS through inhibition of renin or renin-like activity. These findings are potentially related to the development of and/or recovery from acute renal failure in the context of sepsis.