A novel microglial subset plays a key role in myelinogenesis in developing brain

Microglia are resident macrophages of the central nervous system that contribute to homeostasis and neuroinflammation. Although known to play an important role in brain development, their exact function has not been fully described. Here, we show that in contrast to healthy adult and inflammation-activated cells, neonatal microglia show a unique myelinogenic and neurogenic phenotype. A CD11c(+) microglial subset that predominates in primary myelinating areas of the developing brain expresses genes for neuronal and glial survival, migration, and differentiation. These cells are the major source of insulin-like growth factor 1, and its selective depletion from CD11c(+) microglia leads to impairment of primary myelination. CD11c-targeted toxin regimens induced a selective transcriptional response in neonates, distinct from adult microglia. CD11c(+) microglia are also found in clusters of repopulating microglia after experimental ablation and in neuroinflammation in adult mice, but despite some similarities, they do not recapitulate neonatal microglial characteristics. We therefore identify a unique phenotype of neonatal microglia that deliver signals necessary for myelination and neurogenesis

Intrahippocampal clodronate administration alters the brain inflammatory response to systemic LPS in mice

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Spatial heterogeneity of high-resolution Chalk groundwater geochemistry – Underground quarry at Saint Martin-le-Noeud, France

International audienceChalk groundwater is an important aquifer resource in France because it accounts for a production of 12 million m3 y-1 with a large proportion reserved for drinking water. Processes occurring in the unsaturated zone (UZ) and the overlying superficial formations have a high impact on Chalk groundwater geochemistry and require better understanding. The study site is a former underground Chalk quarry located near Beauvais (France) that extends over 1200 m in length, at a depth ranging from 20 to 30 m. The water table intersects the cavity creating 15 underground "lake" that give access to the Chalk groundwater. Lakes geochemistry has been studied: water samples were collected in July 2013 and major ion concentrations were analyzed. UZ and clay-with-flints thickness above each lake were estimated qualitatively using an electromagnetic sensor (EM31) and Underground GPS. The results unexpectedly showed that groundwater quality varied widely in spatial terms for both allochthonous and autochthonous ions (e.g., HCO3- ranged from 2.03 to 4.43 meq L-1, NO3- ranged from 0.21 to 1.33 meq L-1). Principal component analysis indicated the impact of agricultural land use on water quality, with the intake of NO3- as well as SO42-, Cl- and Ca2+. Chalk groundwater geochemistry is compared with the nature and structure of the UZ. We highlight correlations (1) between thick clay-with-flints layers and the ions Mg2+ and K+, and (2) between UZ thickness and Na+. In conclusion, this paper identifies various ion sources (agriculture, clay-with-flints and Chalk) and demonstrates different processes in the UZ: dissolution, ionic exchange and solute storage

Maternal dietary omega-3 deficiency worsens the deleterious effects of prenatal inflammation on the gut-brain axis in the offspring across lifetime

International audienceMaternal immune activation (MIA) and poor maternal nutritional habits are risk factors for the occurrence of neurodevelopmental disorders (NDD). Human studies show the deleterious impact of prenatal inflammation and low n-3 polyunsaturated fatty acid (PUFA) intake on neurodevelopment with long-lasting consequences on behavior. However, the mechanisms linking maternal nutritional status to MIA are still unclear, despite their relevance to the etiology of NDD. We demonstrate here that low maternal n-3 PUFA intake worsens MIA-induced early gut dysfunction, including modification of gut microbiota composition and higher local inflammatory reactivity. These deficits correlate with alterations of microglia-neuron crosstalk pathways and have long-lasting effects, both at transcriptional and behavioral levels. This work highlights the perinatal period as a critical time window, especially regarding the role of the gut-brain axis in neurodevelopment, elucidating the link between MIA, poor nutritional habits, and ND

Maternal dietary omega-3 deficiency worsens the deleterious effects of prenatal inflammation on the gut-brain axis in the offspring across lifetime

Maternal immune activation (MIA) and poor maternal nutritional habits are risk factors for the occurrence of neurodevelopmental disorders (NDD). Human studies show the deleterious impact of prenatal inflammation and low n-3 polyunsaturated fatty acid (PUFA) intake on neurodevelopment with long-lasting consequences on behavior. However, the mechanisms linking maternal nutritional status to MIA are still unclear, despite their relevance to the etiology of NDD. We demonstrate here that low maternal n-3 PUFA intake worsens MIA-induced early gut dysfunction, including modification of gut microbiota composition and higher local inflammatory reactivity. These deficits correlate with alterations of microglia-neuron crosstalk pathways and have long-lasting effects, both at transcriptional and behavioral levels. This work highlights the perinatal period as a critical time window, especially regarding the role of the gut-brain axis in neurodevelopment, elucidating the link between MIA, poor nutritional habits, and NDD