title: Alkaline ceramidase 3 deficiency aggravates colitis and colitis-associated tumorigenesis in mice by hyperactivating the innate immune system.
abstract: Increasing studies suggest that ceramides differing in acyl chain length and/or degree of unsaturation have distinct roles in mediating biological responses. However, still much remains unclear about regulation and role of distinct ceramide species in the immune response. Here, we demonstrate that alkaline ceramidase 3 (Acer3) mediates the immune response by regulating the levels of C18:1-ceramide in cells of the innate immune system and that Acer3 deficiency aggravates colitis in a murine model by augmenting the expression of pro-inflammatory cytokines in myeloid and colonic epithelial cells (CECs). According to the NCBI Gene Expression Omnibus (GEO) database, ACER3 is downregulated in immune cells in response to lipopolysaccharides (LPS), a potent inducer of the innate immune response. Consistent with these data, we demonstrated that LPS downregulated both Acer3 mRNA levels and its enzymatic activity while elevating C(18:1)-ceramide, a substrate of Acer3, in murine immune cells or CECs. Knocking out Acer3 enhanced the elevation of C(18:1)-ceramide and the expression of pro-inflammatory cytokines in immune cells and CECs in response to LPS challenge. Similar to Acer3 knockout, treatment with C(18:1)-ceramide, but not C18:0-ceramide, potentiated LPS-induced expression of pro-inflammatory cytokines in immune cells. In the mouse model of dextran sulfate sodium-induced colitis, Acer3 deficiency augmented colitis-associated elevation of colonic C(18:1)-ceramide and pro-inflammatory cytokines. Acer3 deficiency aggravated diarrhea, rectal bleeding, weight loss and mortality. Pathological analyses revealed that Acer3 deficiency augmented colonic shortening, immune cell infiltration, colonic epithelial damage and systemic inflammation. Acer3 deficiency also aggravated colonic dysplasia in a mouse model of colitis-associated colorectal cancer. Taken together, these results suggest that Acer3 has an important anti-inflammatory role by suppressing cellular or tissue C(18:1)-ceramide, a potent pro-inflammatory bioactive lipid and that dysregulation of ACER3 and C(18:1)-ceramide may contribute to the pathogenesis of inflammatory diseases including cancer.
authors.affiliation: Department of Medicine, State University of New York at Stony Brook University, Stony Brook, NY, USA.|Stony Brook Cancer Center, Stony Brook, NY, USA.|Department of Hepatobiliary Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China.
authors.forename: K
authors.initials: K
authors.lastname: Wang
authors.affiliation: Department of Medicine, State University of New York at Stony Brook University, Stony Brook, NY, USA.|Stony Brook Cancer Center, Stony Brook, NY, USA.
authors.forename: R
authors.initials: R
authors.lastname: Xu
authors.affiliation: Department of Medicine, State University of New York at Stony Brook University, Stony Brook, NY, USA.|Stony Brook Cancer Center, Stony Brook, NY, USA.|Northport Veterans Affairs Medical Center, Northport, NY, USA.
authors.forename: A J
authors.initials: AJ
authors.lastname: Snider
authors.affiliation: Department of Medicine, State University of New York at Stony Brook University, Stony Brook, NY, USA.
authors.forename: J
authors.initials: J
authors.lastname: Schrandt
authors.affiliation: Department of Medicine, State University of New York at Stony Brook University, Stony Brook, NY, USA.|Stony Brook Cancer Center, Stony Brook, NY, USA.
authors.forename: Y
authors.initials: Y
authors.lastname: Li
authors.affiliation: Department of Medicine, State University of New York at Stony Brook University, Stony Brook, NY, USA.
authors.forename: A B
authors.initials: AB
authors.lastname: Bialkowska
authors.affiliation: Department of Gastroenterology, Nanfang Hospital, Southern Medical University, Guangzhou, China.
authors.forename: M
authors.initials: M
authors.lastname: Li
authors.affiliation: Department of Hepatobiliary Surgery, Nanfang Hospital, Southern Medical University, Guangzhou, China.
authors.forename: J
authors.initials: J
authors.lastname: Zhou
authors.affiliation: Department of Medicine, State University of New York at Stony Brook University, Stony Brook, NY, USA.|Stony Brook Cancer Center, Stony Brook, NY, USA.
authors.forename: Y A
authors.initials: YA
authors.lastname: Hannun
authors.affiliation: Department of Medicine, State University of New York at Stony Brook University, Stony Brook, NY, USA.|Stony Brook Cancer Center, Stony Brook, NY, USA.|Northport Veterans Affairs Medical Center, Northport, NY, USA.
authors.forename: L M
authors.initials: LM
authors.lastname: Obeid
authors.affiliation: Department of Medicine, State University of New York at Stony Brook University, Stony Brook, NY, USA.
authors.forename: V W
authors.initials: VW
authors.lastname: Yang
authors.affiliation: Department of Medicine, State University of New York at Stony Brook University, Stony Brook, NY, USA.|Stony Brook Cancer Center, Stony Brook, NY, USA.
authors.forename: C
authors.initials: C
authors.lastname: Mao
mesh_terms: D055574:Alkaline Ceramidase / Q000172:deficiency / Q000235:genetics*; D000818:Animals; D002471:Cell Transformation, Neoplastic; D002518:Ceramides / Q000032:analysis / Q000378:metabolism; D003092:Colitis / Q000209:etiology* / Q000378:metabolism / Q000473:pathology; D003106:Colon / Q000378:metabolism / Q000473:pathology; D016207:Cytokines / Q000378:metabolism; D016264:Dextran Sulfate / Q000633:toxicity; D004195:Disease Models, Animal; D005260:Female; D007113:Immunity, Innate / Q000187:drug effects*; D007963:Leukocytes, Mononuclear / Q000166:cytology / Q000276:immunology / Q000378:metabolism; D008070:Lipopolysaccharides / Q000633:toxicity*; D008297:Male; D051379:Mice; D008810:Mice, Inbred C57BL; D018345:Mice, Knockout; D013379:Substrate Specificity; D015854:Up-Regulation / Q000187:drug effects
chemical_list: D002518:Ceramides; D016207:Cytokines; D008070:Lipopolysaccharides; D016264:Dextran Sulfate; D055574:Alkaline Ceramidase