title: Ceramide synthase 2 deficiency aggravates AOM-DSS-induced colitis in mice: role of colon barrier integrity.
abstract: Loss of intestinal barrier functions is a hallmark of inflammatory bowel disease like ulcerative colitis. The molecular mechanisms are not well understood, but likely involve dysregulation of membrane composition, fluidity, and permeability, which are all essentially regulated by sphingolipids, including ceramides of different chain length and saturation. Here, we used a loss-of-function model (CerS2+/+and CerS2-/-mice) to investigate the impact of ceramide synthase 2, a key enzyme in the generation of very long-chain ceramides, in the dextran sodium salt (DSS) evoked model of UC. CerS2-/-mice developed more severe disease than CerS2+/+mice in acute DSS and chronic AOM/DSS colitis. Deletion of CerS2 strongly reduced very long-chain ceramides (Cer24:0, 24:1) but concomitantly increased long-chain ceramides and sphinganine in plasma and colon tissue. In naive CerS2-/-mice, the expression of tight junction proteins including ZO-1 was almost completely lost in the colon epithelium, leading to increased membrane permeability. This could also be observed in vitro in CerS2 depleted Caco-2 cells. The increase in membrane permeability in CerS2-/-mice did not manifest with apparent clinical symptoms in naive mice, but with slight inflammatory signs such as an increase in monocytes and IL-10. AOM/DSS and DSS treatment alone led to a further deterioration of membrane integrity and to severe clinical symptoms of the disease. This was associated with stronger upregulation of cytokines in CerS2-/-mice and increased infiltration of the colon wall by immune cells, particularly monocytes, CD4+and Th17+T-cells, and an increase in tumor burden. In conclusion, CerS2 is crucial for the maintenance of colon barrier function and epithelial integrity. CerS2 knockdown, and associated changes in several sphingolipids such as a drop in very long-chain ceramides/(dh)-ceramides, an increase in long-chain ceramides/(dh)-ceramides, and sphinganine in the colon, may weaken endogenous defense against the endogenous microbiome.
authors.affiliation: Institute of Clinical Pharmacology, Faculty of Medicine, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
authors.forename: Stephanie
authors.initials: S
authors.lastname: Oertel
authors.affiliation: Institute of Clinical Pharmacology, Faculty of Medicine, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
authors.forename: Klaus
authors.initials: K
authors.lastname: Scholich
authors.affiliation: Institute of Biochemistry I-Pathobiochemistry, Faculty of Medicine, Goethe-University Frankfurt, Frankfurt am Main, Germany.
authors.forename: Andreas
authors.initials: A
authors.lastname: Weigert
authors.affiliation: Institute of Clinical Pharmacology, Faculty of Medicine, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
authors.forename: Dominique
authors.initials: D
authors.lastname: Thomas
authors.affiliation: Institute of Clinical Pharmacology, Faculty of Medicine, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
authors.forename: Julia
authors.initials: J
authors.lastname: Schmetzer
authors.affiliation: Institute of Clinical Pharmacology, Faculty of Medicine, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
authors.forename: Sandra
authors.initials: S
authors.lastname: Trautmann
authors.affiliation: Institute of Clinical Pharmacology, Faculty of Medicine, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
authors.forename: Marthe-Susanna
authors.initials: MS
authors.lastname: Wegner
authors.affiliation: Institute of General Pharmacology and Toxicology, Faculty of Medicine, Goethe-University Frankfurt, Frankfurt am Main, Germany.
authors.forename: Heinfried H
authors.initials: HH
authors.lastname: Radeke
authors.affiliation: Institute of Biostatistics and Mathematical Modeling Faculty of Medicine, Goethe University Frankfurt, Frankfurt am Main, Germany.
authors.forename: Natalie
authors.initials: N
authors.lastname: Filmann
authors.affiliation: Institute of Biochemistry I-Pathobiochemistry, Faculty of Medicine, Goethe-University Frankfurt, Frankfurt am Main, Germany.
authors.forename: Bernhard
authors.initials: B
authors.lastname: Brüne
authors.affiliation: Institute of Clinical Pharmacology, Faculty of Medicine, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.|Fraunhofer Institute for Molecular Biology and Applied Ecology IME, Project Group Translational Medicine and Pharmacology (TMP), Frankfurt am Main, Germany.
authors.forename: Gerd
authors.initials: G
authors.lastname: Geisslinger
authors.affiliation: Institute of Clinical Pharmacology, Faculty of Medicine, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany.
authors.forename: Irmgard
authors.initials: I
authors.lastname: Tegeder
authors.affiliation: Institute of Clinical Pharmacology, Faculty of Medicine, Goethe-University Frankfurt, Theodor-Stern-Kai 7, 60590, Frankfurt am Main, Germany. groesch@em.uni-frankfurt.de.
authors.forename: Sabine
authors.initials: S
authors.lastname: Grösch
mesh_terms: D000818:Animals; D018938:Caco-2 Cells; D002463:Cell Membrane Permeability; D003092:Colitis / Q000139:chemically induced / Q000235:genetics* / Q000276:immunology / Q000473:pathology*; D003106:Colon / Q000276:immunology / Q000473:pathology*; D003911:Dextrans; D004195:Disease Models, Animal; D017353:Gene Deletion; D006801:Humans; D007111:Immunity, Cellular; D051379:Mice; D008810:Mice, Inbred C57BL; D010539:Permeability; D034622:RNA Interference; D034741:RNA, Small Interfering / Q000235:genetics; D013107:Sphingolipids / Q000032:analysis / Q000276:immunology; D051049:Sphingosine N-Acyltransferase / Q000235:genetics* / Q000276:immunology
chemical_list: D003911:Dextrans; D034741:RNA, Small Interfering; D013107:Sphingolipids; C580723:Cers2 protein, mouse; D051049:Sphingosine N-Acyltransferase
keywords: Colon; Cytokines; FITC dextran; Occludin; Sphingosine