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Iwasaki Y, Suganami T, Hachiya R, Shirakawa I, Kim-Saijo M, Tanaka M, Hamaguchi M, Takai-Igarashi T, Nakai M, Miyamoto Y, Ogawa Y. Activating transcription factor 4 links metabolic stress to interleukin-6 expression in macrophages. Diabetes 2014; 63:152-61. [PMID: 23990363 DOI: 10.2337/db13-0757] [Citation(s) in RCA: 83] [Impact Index Per Article: 8.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/13/2022]
Abstract
Chronic inflammation is a molecular element of the metabolic syndrome and type 2 diabetes. Saturated fatty acids (SFAs) are considered to be an important proinflammatory factor. However, it is still incompletely understood how SFAs induce proinflammatory cytokine expression. Hereby we report that activating transcription factor (ATF) 4, a transcription factor that is induced downstream of metabolic stresses including endoplasmic reticulum (ER) stress, plays critical roles in SFA-induced interleukin-6 (Il6) expression. DNA microarray analysis using primary macrophages revealed that the ATF4 pathway is activated by SFAs. Haploinsufficiency and short hairpin RNA-based knockdown of ATF4 in macrophages markedly inhibited SFA- and metabolic stress-induced Il6 expression. Conversely, pharmacological activation of the ATF4 pathway and overexpression of ATF4 resulted in enhanced Il6 expression. Moreover, ATF4 acts in synergy with the Toll-like receptor-4 signaling pathway, which is known to be activated by SFAs. At a molecular level, we found that ATF4 exerts its proinflammatory effects through at least two different mechanisms: ATF4 is involved in SFA-induced nuclear factor-κB activation; and ATF4 directly activates the Il6 promoter. These findings provide evidence suggesting that ATF4 links metabolic stress and Il6 expression in macrophages.
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Affiliation(s)
- Yorihiro Iwasaki
- Department of Molecular Endocrinology and Metabolism, Graduate School of Medical and Dental Sciences, Tokyo Medical and Dental University, Tokyo, Japan
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Ichioka M, Suganami T, Tsuda N, Shirakawa I, Hirata Y, Satoh-Asahara N, Shimoda Y, Tanaka M, Kim-Saijo M, Miyamoto Y, Kamei Y, Sata M, Ogawa Y. Increased expression of macrophage-inducible C-type lectin in adipose tissue of obese mice and humans. Diabetes 2011; 60:819-26. [PMID: 21282371 PMCID: PMC3046842 DOI: 10.2337/db10-0864] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/22/2022]
Abstract
OBJECTIVE We have provided evidence that saturated fatty acids, which are released from adipocytes via macrophage-induced adipocyte lipolysis, serve as a naturally occurring ligand for the Toll-like receptor (TLR) 4 complex in macrophages, thereby aggravating obesity-induced adipose tissue inflammation. The aim of this study was to identify the molecule(s) activated in adipose tissue macrophages in obesity. RESEARCH DESIGN AND METHODS We performed a cDNA microarray analysis of coculture of 3T3-L1 adipocytes and RAW264 macrophages. Cultured adipocytes and macrophages and the adipose tissue of obese mice and humans were used to examine mRNA and protein expression. RESULTS We found that macrophage-inducible C-type lectin (Mincle; also called Clec4e and Clecsf9), a type II transmembrane C-type lectin, is induced selectively in macrophages during the interaction between adipocytes and macrophages. Treatment with palmitate, a major saturated fatty acid released from 3T3-L1 adipocytes, induced Mincle mRNA expression in macrophages at least partly through the TLR4/nuclear factor (NF)-κB pathway. Mincle mRNA expression was increased in parallel with macrophage markers in the adipose tissue of obese mice and humans. The obesity-induced increase in Mincle mRNA expression was markedly attenuated in C3H/HeJ mice with defective TLR4 signaling relative to control C3H/HeN mice. Notably, Mincle mRNA was expressed in bone-marrow cell (BMC)-derived proinflammatory M1 macrophages rather than in BMC-derived anti-inflammatory M2 macrophages in vitro. CONCLUSIONS Our data suggest that Mincle is induced in adipose tissue macrophages in obesity at least partly through the saturated fatty acid/TLR4/NF-κB pathway, thereby suggesting its pathophysiologic role in obesity-induced adipose tissue inflammation.
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Affiliation(s)
- Masayuki Ichioka
- Department of Molecular Medicine and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
| | - Takayoshi Suganami
- Department of Molecular Medicine and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
- Corresponding author: Yoshihiro Ogawa, , or Takayoshi Suganami,
| | - Naoto Tsuda
- Department of Molecular Medicine and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
| | - Ibuki Shirakawa
- Department of Molecular Medicine and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yoichiro Hirata
- Department of Cardiovascular Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
| | - Noriko Satoh-Asahara
- Division of Diabetic Research, Clinical Research Institute, Kyoto Medical Center, Kyoto, Japan
| | - Yuri Shimoda
- Department of Molecular Medicine and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
| | - Miyako Tanaka
- Department of Molecular Medicine and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
| | - Misa Kim-Saijo
- Department of Molecular Medicine and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
| | - Yoshihiro Miyamoto
- Department of Medicine, Division of Atherosclerosis and Diabetes, National Cardiovascular Center Hospital, Osaka, Japan
| | - Yasutomi Kamei
- Department of Molecular Medicine and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
| | - Masataka Sata
- Department of Cardiovascular Medicine, Institute of Health Biosciences, The University of Tokushima Graduate School, Tokushima, Japan
| | - Yoshihiro Ogawa
- Department of Molecular Medicine and Metabolism, Tokyo Medical and Dental University, Tokyo, Japan
- Global Center of Excellence Program, International Research Center for Molecular Science in Tooth and Bone Diseases, Medical Research Institute, Tokyo Medical and Dental University, Tokyo, Japan
- Corresponding author: Yoshihiro Ogawa, , or Takayoshi Suganami,
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Kim-Saijo M, Akamizu T, Ikuta K, Iida Y, Ohmori K, Matsubara K, Matsuda Y, Suzuki M, Matsuda F, Nakao K. Generation of a transgenic animal model of hyperthyroid Graves' disease. Eur J Immunol 2003; 33:2531-8. [PMID: 12938229 DOI: 10.1002/eji.200324255] [Citation(s) in RCA: 24] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Abstract
Graves' disease (GD) is an organ-specific autoimmune disease characterized by hyperthyroidism. Agonistic anti-thyrotropin receptor antibodies (thyroid-stimulating antibodies, TSAb), which mimic the thyrotropin (TSH) action, are thought to cause GD. The precise immunological mechanism of TSAb production, however, remains elusive. Previous immunization approaches using TSH receptor led to transient hyperthyroidism, but did not seem sufficient for comprehensive understanding of the development of autoimmune responses. To create GD-related autoimmunity in mice, we here generated TSAb-transgenic mice in which a patient-derived TSAb is expressed in B cells. Expression of the human TSAb in mice resulted in various manifestations of hyperthyroidism including increased free thyroxine levels with concomitantly decreased TSH levels, increased thyroid uptake of technetium pertechnetate, hyperthermia and thyroid hyperplasia. We found a correlation between the serum levels of human TSAb immunoglobulin and free thyroxine. In addition, conventional B cells expressing the TSAb were partially deleted in the periphery while B1 cells expressing the TSAb persisted and accumulated in the peritoneal cavity, a finding consistent with previous demonstrations that the maintenance of B1 cells plays an important role in the development of autoimmune diseases. Thus, our transgenic mouse may provide a novel and useful animal model for elucidating the pathogenesis and pathophysiology of GD.
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Affiliation(s)
- Misa Kim-Saijo
- Department of Medicine and Clinical Science, Graduate School of Medicine, Kyoto University, Kyoto, Japan
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