title: Involvement of de novo ceramide synthesis in pro-inflammatory adipokine secretion and adipocyte-macrophage interaction.
abstract: Interaction between adipocytes and macrophages has been suggested to play a central role in the pathogenesis of obesity. Ceramide, a sphingolipid de novo synthesized from palmitate, is known to stimulate pro-inflammatory cytokine secretion from multiple types of cells. To clarify whether de novo synthesized ceramide contributes to cytokine dysregulation in adipocytes and macrophages, we observed cytokine secretion in mature 3T3-L1 adipocytes (L1) and RAW264.7 macrophages (RAW) cultured alone or co-cultured under the suppression of de novo ceramide synthesis. Palmitate enhanced ceramide accumulation and stimulated the expression and secretion of interleukin-6 (IL-6) and monocyte chemoattractant protein-1 (MCP-1) in L1. The suppression of serine-palmitoyl transferase, a rate-limiting enzyme of de novo ceramide synthesis, by myriocin or siRNA attenuated those palmitate-induced alterations, and a ceramide synthase inhibitor fumonisin B1 showed similar results. In contrast, the inhibitor of sphingosine kinase or a membrane-permeable ceramide analogue augmented the cytokine secretion. Myriocin effects on the palmitate-induced changes were not abrogated by toll-like receptor-4 blockade. Although palmitate stimulated RAW to secrete tumor necrosis factor-α (TNF-α), it did not significantly increase ceramide content, and neither myriocin nor fumonisin B1 attenuated the TNF-α hypersecretion. The co-culture of L1 with RAW markedly augmented IL-6 and MCP-1 levels in media. Myriocin or fumonisin B1 significantly lowered these cytokine levels and suppressed the gene expression of TNF-α and MCP-1 in RAW and of IL-6 and MCP-1 in L1. In conclusion, de novo synthesized ceramide partially mediates the palmitate effects on pro-inflammatory adipokines and is possibly involved in the interaction with macrophages.
authors.affiliation: Department of Metabolic Medicine, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8550, Japan. Electronic address: yhama@med.nagoya-u.ac.jp.
authors.forename: Yoji
authors.initials: Y
authors.lastname: Hamada
authors.affiliation: Department of Metabolic Medicine, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8550, Japan; Department of Physiology I, School of Medicine, Fujita Health University, 1-98 Kutsukake-cho, Toyoake, Aichi 470-1192, Japan.
authors.forename: Hiroshi
authors.initials: H
authors.lastname: Nagasaki
authors.affiliation: Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Atsushi
authors.initials: A
authors.lastname: Fujiya
authors.affiliation: Department of Metabolic Medicine, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Yusuke
authors.initials: Y
authors.lastname: Seino
authors.affiliation: Pharmaceutical Research Laboratories, Sanwa Kagaku Kenkyusho Co, Ltd, 363 Shiosaki, Hokusei-cho, Inabe 511-0406, Japan; Department of Microbiology, Harbin Medical University, Harbin 150086, China.
authors.forename: Qing-Long
authors.initials: QL
authors.lastname: Shang
authors.affiliation: Pharmaceutical Research Laboratories, Sanwa Kagaku Kenkyusho Co, Ltd, 363 Shiosaki, Hokusei-cho, Inabe 511-0406, Japan.
authors.forename: Takeshi
authors.initials: T
authors.lastname: Suzuki
authors.affiliation: Pharmaceutical Research Laboratories, Sanwa Kagaku Kenkyusho Co, Ltd, 363 Shiosaki, Hokusei-cho, Inabe 511-0406, Japan.
authors.forename: Hiroyuki
authors.initials: H
authors.lastname: Hashimoto
authors.affiliation: Department of Endocrinology and Diabetes, Nagoya University Graduate School of Medicine, 65 Tsuruma-cho, Showa-ku, Nagoya 466-8550, Japan.
authors.forename: Yutaka
authors.initials: Y
authors.lastname: Oiso
mesh_terms: D041721:3T3-L1 Cells; D017667:Adipocytes / Q000378:metabolism*; D054392:Adipokines / Q000378:metabolism*; D000818:Animals; D045744:Cell Line, Tumor; D002518:Ceramides / Q000096:biosynthesis*; D018932:Chemokine CCL2 / Q000235:genetics / Q000378:metabolism; D018920:Coculture Techniques; D005229:Fatty Acids, Monounsaturated / Q000494:pharmacology; D037341:Fumonisins / Q000494:pharmacology; D015850:Interleukin-6 / Q000235:genetics / Q000378:metabolism; D008264:Macrophages / Q000378:metabolism*; D051379:Mice; D010168:Palmitates / Q000494:pharmacology; D012333:RNA, Messenger / Q000235:genetics / Q000378:metabolism; D051102:Serine C-Palmitoyltransferase / Q000378:metabolism; D051197:Toll-Like Receptor 4 / Q000235:genetics / Q000378:metabolism; D014409:Tumor Necrosis Factor-alpha / Q000235:genetics / Q000378:metabolism
chemical_list: D054392:Adipokines; C491768:Ccl2 protein, mouse; D002518:Ceramides; D018932:Chemokine CCL2; D005229:Fatty Acids, Monounsaturated; D037341:Fumonisins; D015850:Interleukin-6; D010168:Palmitates; D012333:RNA, Messenger; C493487:Tlr4 protein, mouse; D051197:Toll-Like Receptor 4; D014409:Tumor Necrosis Factor-alpha; C056933:fumonisin B1; D051102:Serine C-Palmitoyltransferase; C001996:thermozymocidin
keywords: Adipocytes; Ceramide; Cytokines; Macrophages; Palmitate; Serine-palmitoyl transferase