Maternally acquired genotoxic Escherichia coli alters offspring’s intestinal homeostasis

The neonatal gut is rapidly colonized by a newly dominant group of commensal Escherichia coli strains among which a large proportion produces a genotoxin called colibactin. In order to analyze the short- and long-term effects resulting from such evolution, we developed a rat model mimicking the natural transmission of E. coli from mothers to neonates. Genotoxic and non-genotoxic E. coli strains were equally transmitted to the offspring and stably colonized the gut across generations. DNA damage was only detected in neonates colonized with genotoxic E. coli strains. Signs of genotoxic stress such as anaphase bridges, higher occurrence of crypt fission and accelerated renewal of the mature epithelium were detected at adulthood. In addition, we observed alterations of secretory cell populations and gut epithelial barrier. Our findings illustrate how critical is the genotype of E. coli strains acquired at birth for gut homeostasis at adulthood.     

Targeting the histone demethylase LSD1 prevents cardiomyopathy in a mouse model of laminopathy

LMNA mutations in patients are responsible for a dilated cardiomyopathy. Molecular mechanisms underlying the origin and development of the pathology are unknown. Herein, using mouse pluripotent embryonic stem cells (ESCs) and a mouse model both harboring the p.H222P Lmna mutation, we found early defects in cardiac differentiation of mutated ESCs and dilatation of mutated embryonic hearts at E13.5, pointing to a developmental origin of the disease. Using mouse ESCs, we demonstrated that cardiac differentiation of Lmna^H222P/+ was impaired at the mesodermal stage. Expression of Mesp1, a mesodermal cardiogenic gene involved in epithelial-to-mesenchymal transition of epiblast cells, as well as Snai1 and Twist expression, was decreased in Lmna^H222P/+ cells compared with WT cells in the course of differentiation. In turn, cardiomyocyte differentiation was impaired. ChIP assay of H3K4me1 in differentiating cells revealed a specific decrease of this histone mark on regulatory regions of Mesp1 and Twist in Lmna^H222P/+ cells. Downregulation or inhibition of LSD1 that specifically demethylated H3K4me1 rescued the epigenetic landscape of mesodermal Lmna^H222P/+ cells and in turn contraction of cardiomyocytes. Inhibition of LSD1 in pregnant mice or neonatal mice prevented cardiomyopathy in E13.5 Lmna^H222P/H222P offspring and adults, respectively. Thus, LSD1 appeared to be a therapeutic target to prevent or cure dilated cardiomyopathy associated with a laminopathy.     

Décrochage du sens moral au sein des forces armées en milieu opérationnel : une approche constructive

Despite the international ratification of Geneva Conventions, which define rules to protect people in situations of war, violence beyond the law of armed conflict is not uncommon. Fairly regularly, the subject makes the headlines. A notable example is the recent publication of confidential informations by Wikileaks. What is at stake is the coherence of UN mandates to western armies. This coherence contributes to the preservation of mental balance of military forces.     

Ventricular allorhythmia during infarct-related ventricular tachycardia

Ventricular allorhythmia is an electrocardiogram feature leading to a pattern of "regularly irregular" arrhythmia mainly reported during non-life-threatening organized atrial tachycardia. We report the infrequent case of a patient presenting with ventricular allorhythmia during infarct-related ventricular tachycardia. The potential mechanisms of this tachycardia are discussed.     

Ly6Chigh Monocytes Protect against Kidney Damage during Sepsis via a CX3CR1-Dependent Adhesion Mechanism

Monocytes have a crucial role in both proinflammatory and anti-inflammatory phenomena occurring during sepsis. Monocyte recruitment and activation are orchestrated by the chemokine receptors CX3CR1 and CCR2 and their cognate ligands. However, little is known about the roles of these cells and chemokines during the acute phase of inflammation in sepsis. Using intravital microscopy in a murine model of polymicrobial sepsis, we showed that inflammatory Ly6C^high monocytes infiltrated kidneys, exhibited altered motility, and adhered strongly to the renal vascular wall in a chemokine receptor CX3CR1-dependent manner. Adoptive transfer of Cx3cr1-proficient monocyte-enriched bone marrow cells into septic Cx3cr1-depleted mice prevented kidney damage and promoted mouse survival. Modulation of CX3CR1 activation in septic mice controlled monocyte adhesion, regulated proinflammatory and anti-inflammatory cytokine expression, and was associated with the extent of kidney lesions such that the number of lesions decreased when CX3CR1 activity increased. Consistent with these results, the pro-adhesive I249 CX3CR1 allele in humans was associated with a lower incidence of AKI in patients with sepsis. These data show that inflammatory monocytes have a protective effect during sepsis via a CX3CR1-dependent adhesion mechanism. This receptor might be a new therapeutic target for kidney injury during sepsis.