Dual RNA Seq of Salmonella-positive and Salmonella-negative small intestinal epithelial cells using the neonatal infection model
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ABSTRACT: The intestinal epithelium is the first line of defence against invasive enteric pathogens. Removal of infected cells by exfoliation prevents mucosal translocation and systemic infection in the adult host, but is less commonly observed in the neonatal small intestine. Instead, here we describe non-professional efferocytosis of Salmonella-infected enterocytes by neighbouring intestinal epithelial cells in the neonatal intestine. Intestinal epithelial stem cell organoid co-cultures of neonatal and adult cell monolayers with damaged enterocytes replicated this observation, confirmed the age-dependent ability of intestinal epithelial cells for efferocytosis and identified the critical involvement of the 'eat-me' signals and adaptors phosphatidylserine and C1q as well as the 'eat-me' receptors integrin-v (CD51) and CD36 in cellular uptake. Consistent with this, massive epithelial cell membrane protrusions and CD36 accumulation at the contact site with apoptotic cells were observed in the infected neonatal host in vivo. Efferocytosis of infected small intestinal enterocytes by neighbouring epithelial cells may represent a previously unrecognised mechanism of neonatal antimicrobial host defense to maintain barrier integrity.
Project description:The translocation of macromolecules across the mammalian intestinal epithelial barrier is enhanced in early life before ceasing at what has been termed gut closure. However, the translocated macromolecules, the mechanism of translocation, and the functional consequences for the neonatal liver, which is still a hematopoietic organ at this age in mice, have not been defined. Microbiota profiling identified a transiently increased abundance of small intestinal lipopolysaccharide (LPS)-producing g-Proteobacteria early after birth. Orally administered LPS was translocated across the mucosal barrier during this early postnatal window, resulting in increased hepatic cytokine expression. LPS translocation was independent of disabled homolog 2 (Dab2)-mediated endocytosis by fetal-like enterocytes, but was mediated by the fatty acid translocase CD36, which showed transient overexpression early after birth. Postnatal LPS exposure altered hepatic haematopoiesis, innate immune reactivity and the bacterial clearance capacity of the neonatal liver. Taken together, our results identify and characterise a postnatal time window of hepatic tissue stimulation by gut-derived LPS as a novel immune priming event in early life.
Project description:The apical aspects of absorptive epithelial cells form a highly organized brush border membrane (BBM), shaped by densely packed microvilli that are coated with a glycocalyx. Here, we present evidence showing that the glycocalyx forms an epithelial barrier that prevents exogenous molecules from gaining access to the BBM. We used a multiomics approach to investigate function and regulation of membrane mucins exposed on the enterocytic BBM during postnatal development of the small intestine. Muc17 was identified as a major membrane mucinin the glycocalyx that was specifically upregulated by IL-22 as part of an epithelial defense repertoire during suckling-weaning transition. High levels of IL-22 at the time of weaning primed progenitor enterocyte to express Muc17 as they migrate out of intestinal crypts to replace neonatal enterocytes. Our findings propose a role for membrane mucin Muc17 in epithelial barrier function in the small intestine.
Project description:Digested dietary fats are taken up, processed and transported by enterocytes to supply the body with lipids. Most absorbed lipids are assembled into pre-chylomicrons in the endoplasmic reticulum (ER) of enterocytes, which are then transported to the Golgi for maturation and subsequent secretion to the circulation. The role of mitochondria in regulating intestinal lipid transport remains unknown. Here we show that mitochondrial dysfunction in enterocytes inhibits chylomicron production and the transport of dietary lipids to peripheral organs. Mice with intestinal epithelial cell (IEC)-specific ablation of the mitochondrial-specific aspartyl - tRNA synthetase DARS2, as well as of the respiratory chain subunit SDHA or the assembly factor COX10 failed to thrive and showed massive accumulation of lipids within large lipid droplets (LDs) in enterocytes of the proximal small intestine (SI). Feeding a fat-free diet inhibited the formation of LDs in DARS2-deficient enterocytes, showing that accumulating lipids derive mostly from digested fat. Furthermore, metabolic tracing studies revealed impaired transport of dietary lipids to peripheral organs in mice lacking DARS2 in IECs. Moreover, DARS2-deficient enterocytes showed a distinct lack of mature chylomicrons concomitant with a disorganisation of the Golgi apparatus, suggesting that impaired ER to Golgi trafficking underlies impaired chylomicron production and secretion. Taken together, these results revealed a vital role of mitochondria in regulating dietary lipid transport in enterocytes, which is relevant for understanding the intestinal and nutritional defects observed in patients with mitochondrial defects.
Project description:1-day-old C57BL/6 mice were left untreated (co) or orally infected with 10E2 CFU wildtype (wt) or delta invC SPI1 mutant Salmonella Typhimurium (ATCC14028). Four biological replicates obtained from individual animals were exmained; each group contained animals from at least 2 different litters. On day 4 p.i., animals were sacrificed and intestinal epithelial cells were isolated from total small intestine (protocol according to: Lotz et al., J. Exp. Med. 2006). Total RNA was isolated by TriZol and its purity was examined using a Bioanalyzer. We used microarrays to detail the global gene expression in primary total isolated intestinal epithelial cells. Four biological replicates of isolated intestinal epithelial cells obtained 4 daysp.i. from neonate mice infected at the age of 1 day (each group with animals from at least two litteres). Single color array.
Project description:To investigate NF-kB-driven gene expression in IEC, we performed microarray analysis from enterocytes of mice that express a constitutively active form of IKKb in intestinal epithelial cells Total RNA was prepared from enterocytes obtained from small intestines of IKKb(EE)IEC and WT littermates. Two biological replicates were performed for each experimental condition.
Project description:Park, D, Brune, KA, Mitra, A, Marusina, AI, Maverakis, E, Lebrilla, CB. Characteristic Changes in Cell Surface Glycosylation Accompany Intestinal Epithelial Cell Differentiation: High Mannose Structures Dominate the Cell Surface Glycome of Undifferentiated Enterocytes, Molecular and Cellular Proteomics: submitted.
Project description:This SuperSeries is composed of the following subset Series: GSE41541: Expression data from mouse proximal intestinal epithelial Lgr5(hi) stem cells and differentiated villus cells (enterocytes from Atoh1 conditional knockout) GSE41542: H3K79me2 ChIP-seq in mouse proximal intestinal Lgr5(hi) stem cells and villus cells GSE41710: Global gene expression analysis of Dot1l-deficient and control intestinal villus cells in mouse Refer to individual Series
Project description:Monocytes and macrophages as components of innate immunity are critical for both homeostasis and inflammation. The scavenger receptor CD36, highly expressed in macrophages, promotes immunological responses mediated by recognition of molecular patterns on pathogens or endogenous ligands on apoptotic cells. CD36 mediated lipid uptake also allows metabolic adaptations that influence macrophage phenotype and polarization. CD36 binds diverse lipids including fatty acids and various lipoproteins, which could exert differential effects on macrophage conversion. Previous studies reported opposite outcomes due to CD36-mediated lipid uptake; macrophages converted to either an inflammatory or an alternatively activated phenotype. To determine the role of this receptor in vivo in the presence of physiological lipid sources, we created macrophage-specific CD36 knockout mice. Using zymosan-induced peritonitis to activate immune cells, we show through single cell RNA sequencing analysis that a broad variety of resident and infiltrated immune cells are present in the peritoneum 72h after the initial stimulus. CD36 deficiency did not affect the numbers of cells during the infiltration and resolution phases, but CD36 deficiency altered the macrophage transcriptome. Pathways related to innate immunity, antigen presentation and oxidative phosphorylation were upregulated in macrophages with CD36 deficiency, whereas those related to efferocytosis, adaptive immunity and B cell activation were downregulated. Despite these gene changes, neither immunoglobulin production nor peritoneal efferocytosis was altered by macrophage CD36 deficiency, nor were there changes in the numbers of circulating white blood cells. Thus, CD36 deficiency does not reduce the inflammatory phenotype of induced peritoneal macrophages.
Project description:1-day-old C57BL/6 mice were left untreated (co) or orally infected with 10E2 CFU wildtype (wt) or delta invC SPI1 mutant Salmonella Typhimurium (ATCC14028). Four biological replicates obtained from individual animals were exmained; each group contained animals from at least 2 different litters. On day 4 p.i., animals were sacrificed and intestinal epithelial cells were isolated from total small intestine (protocol according to: Lotz et al., J. Exp. Med. 2006). Total RNA was isolated by TriZol and its purity was examined using a Bioanalyzer. We used microarrays to detail the global gene expression in primary total isolated intestinal epithelial cells.
Project description:Villin-Cre+ Lsd1fl/fl (cKO) mice display an immature intestinal epithelium characterized by an incomplete differentiation of enterocytes and secretory lineages, reduced number of goblet cells and a complete loss of Paneth cells. This experiment aims to elucidate the differences in stool microbial composition derived from WT (Villin-Cre- Lsd1fl/fl) and cKO mice both in adult (2-month-old) and neonatal (14 days postpartum P14) stages. Different timepoints are crucial to understand the role of intestinal maturation in microbiome composition since said maturation is dependent on time-dependent external cues happening at P14-21 (weaning and transition from milk to solid foods).