Human erythroid differentiation requires VDAC1-mediated mitochondrial clearance

Erythroblast maturation in mammals is dependent on organelle clearance throughout terminal erythropoiesis. We studied the role of the outer mitochondrial membrane protein voltage-dependent anion channel-1 (VDAC1) in human terminal erythropoiesis. We show that short hairpin (shRNA)-mediated downregulation of VDAC1 accelerates erythroblast maturation. Thereafter, erythroblasts are blocked at the orthochromatic stage, exhibiting a significant decreased level of enucleation, concomitant with an increased cell death. We demonstrate that mitochondria clearance starts at the transition from basophilic to polychromatic erythroblast, and that VDAC1 downregulation induces the mitochondrial retention. In damaged mitochondria from non-erythroid cells, VDAC1 was identified as a target for Parkin-mediated ubiquitination to recruit the phagophore. Here, we showed that VDAC1 is involved in phagophore’s membrane recruitment regulating selective mitophagy of still functional mitochondria from human erythroblasts. These findings demonstrate for the first time a crucial role for VDAC1 in human erythroblast terminal differentiation, regulating mitochondria clearance.Fil: Moras, Martina. Universite de Paris; Francia. Institut National de Transfusion Sanguine; Francia. Laboratoire d’Excellence GR-Ex; FranciaFil: Hattab, Claude. Universite de Paris; Francia. Institut National de Transfusion Sanguine; Francia. Laboratoire d’Excellence GR-Ex; FranciaFil: Gonzalez Menendez, Pedro. Laboratoire d’Excellence GR-Ex; Francia. Université Montpellier II; Francia. Centre National de la Recherche Scientifique; FranciaFil: Fader Kaiser, Claudio Marcelo. Consejo Nacional de Investigaciones Científicas y Técnicas. Centro Científico Tecnológico Conicet - Mendoza. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos. Universidad Nacional de Cuyo. Facultad de Ciencias Médicas. Instituto de Histología y Embriología de Mendoza Dr. Mario H. Burgos; Argentina. Universidad Nacional de Cuyo. Facultad de Odontologia; ArgentinaFil: Dussiot, Michael. Universite de Paris; Francia. Laboratoire d’Excellence GR-Ex; FranciaFil: Larghero, Jerome. Hôpital Saint-Louis. Unité de Thérapie cellulaire; FranciaFil: Le Van Kim, Caroline. Universite de Paris; Francia. Institut National de Transfusion Sanguine; Francia. Laboratoire d’Excellence GR-Ex; FranciaFil: Kinet, Sandrina. Laboratoire d’Excellence GR-Ex; Francia. Université Montpellier II; Francia. Centre National de la Recherche Scientifique; FranciaFil: Taylor, Naomi. Laboratoire d’Excellence GR-Ex; Francia. Centre National de la Recherche Scientifique; Francia. Université Montpellier II; Francia. Center for Cancer Research; Estados UnidosFil: Lefevre, Sophie D.. Universite de Paris; Francia. Institut National de Transfusion Sanguine; Francia. Laboratoire d’Excellence GR-Ex; FranciaFil: Ostuni, Mariano. Universite de Paris; Francia. Institut National de Transfusion Sanguine; Francia. Laboratoire d’Excellence GR-Ex; Franci

Macrophage Plasticity in Experimental Atherosclerosis

As in human disease, macrophages (MØ) are central players in the development and progression of experimental atherosclerosis. In this study we have evaluated the phenotype of MØ associated with progression of atherosclerosis in the apolipoprotein E (ApoE) knockout (KO) mouse model

Ineffective Erythropoiesis in β

In humans, β-thalassemia dyserythropoiesis is characterized by expansion of early erythroid precursors and erythroid progenitors and then ineffective erythropoiesis. This ineffective erythropoiesis is defined as a suboptimal production of mature erythrocytes originating from a proliferating pool of immature erythroblasts. It is characterized by (1) accelerated erythroid differentiation, (2) maturation blockade at the polychromatophilic stage, and (3) death of erythroid precursors. Despite extensive knowledge of molecular defects causing β-thalassemia, less is known about the mechanisms responsible for ineffective erythropoiesis. In this paper, we will focus on the underlying mechanisms leading to premature death of thalassemic erythroid precursors in the bone marrow

Iron overload across the spectrum of non-transfusion-dependent thalassaemias: role of erythropoiesis, splenectomy and transfusions

Non-transfusion-dependent thalassaemias (NTDT) encompass a spectrum of anaemias rarely requiring blood transfusions. Increased iron absorption, driven by hepcidin suppression secondary to erythron expansion, initially causes intrahepatic iron overload. We examined iron metabolism biomarkers in 166 NTDT patients with β thalassaemia intermedia (n = 95), haemoglobin (Hb) E/β thalassaemia (n = 49) and Hb H syndromes (n = 22). Liver iron concentration (LIC), serum ferritin (SF), transferrin saturation (TfSat) and non-transferrin-bound iron (NTBI) were elevated and correlated across diagnostic subgroups. NTBI correlated with soluble transferrin receptor (sTfR), labile plasma iron (LPI) and nucleated red blood cells (NRBCs), with elevations generally confined to previously transfused patients. Splenectomised patients had higher NTBI, TfSat, NRBCs and SF relative to LIC, than non-splenectomised patients. LPI elevations were confined to patients with saturated transferrin. Erythron expansion biomarkers (sTfR, growth differentiation factor-15, NRBCs) correlated with each other and with iron overload biomarkers, particularly in Hb H patients. Plasma hepcidin was similar across subgroups, increased with >20 prior transfusions, and correlated inversely with TfSat, NTBI, LPI and NRBCs. Hepcidin/SF ratios were low, consistent with hepcidin suppression relative to iron overload. Increased NTBI and, by implication, risk of extra-hepatic iron distribution are more likely in previously transfused, splenectomised and iron-overloaded NTDT patients with TfSat >70%

Physiological Induction of Regulatory Qa-1-Restricted CD8+ T Cells Triggered by Endogenous CD4+ T Cell Responses

T cell-dependent autoimmune diseases are characterized by the expansion of T cell clones that recognize immunodominant epitopes on the target antigen. As a consequence, for a given autoimmune disorder, pathogenic T cell clones express T cell receptors with a limited number of variable regions that define antigenic specificity. Qa-1, a MHC class I-like molecule, presents peptides from the variable region of TCRs to Qa-1-restricted CD8+ T cells. The induction of Vß-specific CD8+ T cells has been harnessed in an immunotherapeutic strategy known as the “T cell vaccination” (TCV) that comprises the injection of activated and attenuated CD4+ T cell clones so as to induce protective CD8+ T cells. We hypothesized that Qa-1-restricted CD8+ regulatory T cells could also constitute a physiologic regulatory arm of lymphocyte responses upon expansion of endogenous CD4+ T cells, in the absence of deliberate exogenous T cell vaccination. We immunized mice with two types of antigenic challenges in order to sequentially expand antigen-specific endogenous CD4+ T cells with distinct antigenic specificities but characterized by a common Vß chain in their TCR. The first immunization was performed with a non-self antigen while the second challenge was performed with a myelin-derived peptide known to drive experimental autoimmune encephalomyelitis (EAE), a mouse model of multiple sclerosis. We show that regulatory Vß-specific Qa-1-restricted CD8+ T cells induced during the first endogenous CD4+ T cell responses are able to control the expansion of subsequently mobilized pathogenic autoreactive CD4+ T cells. In conclusion, apart from the immunotherapeutic TCV, Qa-1-restricted specialized CD8+ regulatory T cells can also be induced during endogenous CD4+ T cell responses. At variance with other regulatory T cell subsets, the action of these Qa-1-restricted T cells seems to be restricted to the immediate re-activation of CD4+ T cells

Modulation of Macrophage Activation State Protects Tissue from Necrosis during Critical Limb Ischemia in Thrombospondin-1-Deficient Mice

International audienceBACKGROUND: Macrophages, key regulators of healing/regeneration processes, strongly infiltrate ischemic tissues from patients suffering from critical limb ischemia (CLI). However pro-inflammatory markers correlate with disease progression and risk of amputation, suggesting that modulating macrophage activation state might be beneficial. We previously reported that thrombospondin-1 (TSP-1) is highly expressed in ischemic tissues during CLI in humans. TSP-1 is a matricellular protein that displays well-known angiostatic properties in cancer, and regulates inflammation in vivo and macrophages properties in vitro. We therefore sought to investigate its function in a mouse model of CLI. METHODS AND FINDINGS: Using a genetic model of tsp-1(-/-) mice subjected to femoral artery excision, we report that tsp-1(-/-) mice were clinically and histologically protected from necrosis compared to controls. Tissue protection was associated with increased postischemic angiogenesis and muscle regeneration. We next showed that macrophages present in ischemic tissues exhibited distinct phenotypes in tsp-1(-/-) and wt mice. A strong reduction of necrotic myofibers phagocytosis was observed in tsp-1(-/-) mice. We next demonstrated that phagocytosis of muscle cell debris is a potent pro-inflammatory signal for macrophages in vitro. Consistently with these findings, macrophages that infiltrated ischemic tissues exhibited a reduced postischemic pro-inflammatory activation state in tsp-1(-/-) mice, characterized by a reduced Ly-6C expression and a less pro-inflammatory cytokine expression profile. Finally, we showed that monocyte depletion reversed clinical and histological protection from necrosis observed in tsp-1(-/-) mice, thereby demonstrating that macrophages mediated tissue protection in these mice. CONCLUSION: This study defines targeting postischemic macrophage activation state as a new potential therapeutic approach to protect tissues from necrosis and promote tissue repair during CLI. Furthermore, our data suggest that phagocytosis plays a crucial role in promoting a deleterious intra-tissular pro-inflammatory macrophage activation state during critical injuries. Finally, our results describe TSP-1 as a new relevant physiological target during critical leg ischemia

Peritoneal Sclerosis in a Patient on Long-term Continuous Ambulatory Peritoneal Dialysis (CAPD). : An Autopsy Case.

若年性ネフロン癆による慢性腎不全でCAPD (continuous ambulatory peritoneal dialysis)導入し, 6年6ヵ月後に死亡した20歳男性の1剖検例を報告した。CAPD導入数カ月後, 腹膜炎による除水能低下を起こしたが, 約5ヵ月後に回復した。CAPD導入1年5ヵ月以降重症な腹膜炎罹患により除水能低下状態が遷延したが, 次第に回復した。しかし, 体液貯留傾向のため, 3年2ヵ月後より高張透析液を使用し除水量の増加を得たが, 3年9ヵ月後に不可逆的な除水能低下状態となった。一方, クレアチニンの透析排液/血漿濃度比(D/P)から見た溶質除去能は, その約半年後まで保たれており, 血清クレアチニン値の上昇は軽度であった。剖検にて腹膜の線維性肥厚と高度の内腔狭窄を伴う動静脈硬化を認め, 腹膜硬化症と診断した。本例の腹膜硬化症は, 頻回の腹膜炎と高張透析液の使用が主な原因と考えられた。腹膜機能を長期に維持するためには, 腹膜炎の予防と高張透析液の使用を最小限にすることが重要と考えられた。A 20-year-old man, treated with continuous ambulatory peritoneal dialysis (CAPD) for 6.5 years because of-end-stage renal disease due to juvenile nephronophthysis, died of ultrafiltration failure, and the morphological examination of peritoneum was carried out at autopsy. Nine episodes of peritonitis developed, and ultrafiltration transiently decreased after each episodes. At 2 years after the start of CAPD, severe peritonitis occurred, and then his body weight and blood pressure gradually increased. At 4 years after the beginning of CAPD, when hyperosmotic dialysate was frequently used, ultrafiltration was irreversively deteriorated. On the other hand, creatinine dialysate/plasma ratio remained within normal limits for about several months, and the increase in the level of serum creatinine was very little. The peritoneum obtained at autopsy revealed marked fibrous thickening as well as the conspicuous luminal narrowing of arteries and veins due to intimal thickening. The development of peritoneal sclerosis seemed to be related with the frequency and severity of peritonitis and the use of hyperosmotic dialysate

Type I interferon-mediated autoinflammation due to DNase II deficiency

Microbial nucleic acid recognition serves as the major stimulus to an antiviral response, implying a requirement to limit the misrepresentation of self nucleic acids as non-self and the induction of autoinflammation. By systematic screening using a panel of interferon-stimulated genes we identify two siblings and a singleton variably demonstrating severe neonatal anemia, membranoproliferative glomerulonephritis, liver fibrosis, deforming arthropathy and increased anti-DNA antibodies. In both families we identify biallelic mutations in DNASE2, associated with a loss of DNase II endonuclease activity. We record increased interferon alpha protein levels using digital ELISA, enhanced interferon signaling by RNA-Seq analysis and constitutive upregulation of phosphorylated STAT1 and STAT3 in patient lymphocytes and monocytes. A hematological disease transcriptomic signature and increased numbers of erythroblasts are recorded in patient peripheral blood, suggesting that interferon might have a particular effect on hematopoiesis. These data define a type I interferonopathy due to DNase II deficiency in humans

What prospective and nutritional modalities in the framework of a proflexitarian transition of the diet of French adults? Analysis of the nutritional and dietary levers and brakes on the reduction of meat consumption

Alors que la place de la viande et des produits carnés dans une alimentation durable est devenue un sujet de société, c'est un sujet scientifique qui n'a pas été suffisamment exploré rationnellement par une approche d'analyse systémique, et les preuves scientifiques restent fragmentaires. De nombreuses études ont porté sur quelques nutriments importants qui sont apportés par la viande (par exemple, les protéines, le zinc, la vitamine B12), et dont l’insuffisance d’apport peut avoir des conséquences sévères, sans analyser de manière hiérarchique dans quelle mesure ces nutriments sont effectivement critiques, et quels remodelages du régime alimentaire pourraient offrir des solutions à la réduction de la viande tout en conduisant à des régimes plus durables.Nos résultats fournissent des preuves solides quant aux nutriments les plus limitants (fer et zinc biodisponibles, vitamine A) lors de la diminution de la viande. Les régimes alimentaires modélisés comportaient davantage de fruits, de légumes et de céréales complètes et étaient plus sains que les régimes occidentaux de référence. Ces changements alimentaires ont également entraîné une diminution des pressions sur l'environnement liées à l'alimentation. Certains nutriments n’étaient jamais en cause lorsqu'on simule une transition vers des régimes sans viande (comme les protéines et les acides aminés indispensables, et la vitamine B12). En mettant en évidence les problèmes de nutriments et les solutions diététiques lors de la réduction de la viande, notre étude fournit une analyse claire et détaillée de l'importance de la viande dans les régimes alimentaires durables. Nous pensons qu'il s'agit d'une contribution importante à un sujet majeur de la nutrition.While the importance of meat has become a societal topic, it is a scientific subject that has not been sufficiently explored rationally by a systemic analysis approach, and the evidence remains fragmented. Many studies reported on a few important nutrients that are conveyed by meat (e.g. protein, zinc, vitamin B12), and whose inadequate intake can have severe consequences, without analyzing in a hierarchical way to what extent nutrients brought by meat are indeed critical and which remodeling of the diet could offer solutions to the reduction of meat while leading to more sustainable diets.Our results provide strong evidence as to which nutrients are the most limiting (bioavailable iron and zinc, vitamin A) when decreasing meat. Modeled dietary patterns included more fruits, vegetables and whole grain products, and were healthier than typical Western diets. These dietary changes led to a reduction in environmental pressures. Some nutrients were never at issue when simulating a transition toward meat-free diets (such as protein and essential amino acids and vitamin B12). By pointing out the nutrient issues and dietary solutions when reducing meat, our study provides a clear and detailed analysis of the importance of meat in healthy diets. We believe it would make an important contribution to a major topic in nutrition