151
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Chen CA, Carolan PC, Annes JP. In vivo screening for secreted proteins that modulate glucose handling identifies interleukin-6 family members as potent hypoglycemic agents. PLoS One 2012; 7:e44600. [PMID: 22962620 PMCID: PMC3433445 DOI: 10.1371/journal.pone.0044600] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/18/2012] [Accepted: 08/09/2012] [Indexed: 11/18/2022] Open
Abstract
Diabetes is a disease of abnormal glucose homeostasis characterized by chronic hyperglycemia and a broad array of consequent organ damage. Because normal glucose homeostasis is maintained by a complex interaction between behavior (feeding and physical activity) and metabolic activity that is modulated by inter-organ signaling through secreted factors, disease modeling in vitro is necessarily limited. In contrast, in vivo studies allow complex metabolic phenotypes to be studied but present a barrier to high throughput studies. Here we present the development of a novel in vivo screening platform that addresses this primary limitation of in vivo experimentation. Our platform leverages the large secretory capacity of the liver and the hepatocyte transfection technique of hydrodynamic tail vein injection to achieve supraphysiologic blood levels of secreted proteins. To date, the utility of hydrodynamic transfection has been limited by the deleterious impact of the variable transfection efficiency inherent to this technique. We overcome this constraint by co-transfection of a secreted luciferase cDNA whose product can be easily monitored in the blood of a living animal and used as a surrogate marker for transfection efficiency and gene expression levels. To demonstrate the utility of our strategy, we screened 248 secreted proteins for the ability to enhance glucose tolerance. Surprisingly, interleukin-6 and several of its family members but not other well-recognized insulin sensitizing agents were identified as potent hypoglycemic factors. We propose this experimental system as a powerful and flexible in vivo screening platform for identifying genes that modulate complex behavioral and metabolic phenotypes.
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Affiliation(s)
- Chen Amy Chen
- Department of Stem Cell and Regenerative Biology, Harvard University, Cambridge, Massachusetts, United States of America
| | - Peter C. Carolan
- Department of Medicine, Massachusetts General Hospital, Boston, Massachusetts, United States of America
| | - Justin P. Annes
- Department of Medicine, Stanford University Medical School, Stanford, California, United States of America
- * E-mail:
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152
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Xu E, Charbonneau A, Rolland Y, Bellmann K, Pao L, Siminovitch KA, Neel BG, Beauchemin N, Marette A. Hepatocyte-specific Ptpn6 deletion protects from obesity-linked hepatic insulin resistance. Diabetes 2012; 61:1949-58. [PMID: 22698917 PMCID: PMC3402325 DOI: 10.2337/db11-1502] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/20/2022]
Abstract
The protein-tyrosine phosphatase Shp1 negatively regulates insulin action on glucose homeostasis in liver and muscle, but its potential role in obesity-linked insulin resistance has not been examined. To investigate the role of Shp1 in hepatic insulin resistance, we generated hepatocyte-specific Shp1 knockout mice (Ptpn6(H-KO)), which were subjected to extensive metabolic monitoring throughout an 8-week standard chow diet (SD) or high-fat diet (HFD) feeding. We report for the first time that Shp1 expression is upregulated in metabolic tissues of HFD-fed obese mice. When compared with their Shp1-expressing Ptpn6(f/f) littermates, Ptpn6(H-KO) mice exhibited significantly lowered fasting glycemia and heightened hepatic insulin sensitivity. After HFD feeding, Ptpn6(H-KO) mice developed comparable levels of obesity as Ptpn6(f/f) mice, but they were remarkably protected from liver insulin resistance, as revealed by euglycemic clamps and hepatic insulin signaling determinations. Although Ptpn6(H-KO) mice still acquired diet-induced peripheral insulin resistance, they were less hyperinsulinemic during a glucose tolerance test because of reduced insulin secretion. Ptpn6(H-KO) mice also exhibited increased insulin clearance in line with enhanced CC1 tyrosine phosphorylation in liver. These results show that hepatocyte Shp1 plays a critical role in the development of hepatic insulin resistance and represents a novel therapeutic target for obesity-linked diabetes.
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Affiliation(s)
- Elaine Xu
- Department of Medicine, Faculty of Medicine, Cardiology Axis of the Institut Universitaire de Cardiologie et de Pneumologie de Québec (Hôpital Laval), Québec, Québec, Canada
- Department of Metabolism, Vascular and Renal Health Axis, Laval University Hospital Research Center, Québec, Québec, Canada
| | - Alexandre Charbonneau
- Department of Medicine, Faculty of Medicine, Cardiology Axis of the Institut Universitaire de Cardiologie et de Pneumologie de Québec (Hôpital Laval), Québec, Québec, Canada
- Department of Metabolism, Vascular and Renal Health Axis, Laval University Hospital Research Center, Québec, Québec, Canada
| | - Yannève Rolland
- Department of Medicine, Faculty of Medicine, Cardiology Axis of the Institut Universitaire de Cardiologie et de Pneumologie de Québec (Hôpital Laval), Québec, Québec, Canada
- Department of Metabolism, Vascular and Renal Health Axis, Laval University Hospital Research Center, Québec, Québec, Canada
| | - Kerstin Bellmann
- Department of Medicine, Faculty of Medicine, Cardiology Axis of the Institut Universitaire de Cardiologie et de Pneumologie de Québec (Hôpital Laval), Québec, Québec, Canada
- Department of Metabolism, Vascular and Renal Health Axis, Laval University Hospital Research Center, Québec, Québec, Canada
| | - Lily Pao
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, Princess Margaret Hospital and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Katherine A. Siminovitch
- Department of Medicine, University of Toronto, Mount Sinai Hospital Samuel Lunenfeld Research Institute, Toronto, Ontario, Canada
| | - Benjamin G. Neel
- Campbell Family Cancer Research Institute, Ontario Cancer Institute, Princess Margaret Hospital and Department of Medical Biophysics, University of Toronto, Toronto, Ontario, Canada
| | - Nicole Beauchemin
- Goodman Cancer Research Centre, McGill University, Montréal, Québec, Canada
- Departments of Biochemistry, Medicine, and Oncology, McGill University, Montréal, Québec, Canada
| | - André Marette
- Department of Medicine, Faculty of Medicine, Cardiology Axis of the Institut Universitaire de Cardiologie et de Pneumologie de Québec (Hôpital Laval), Québec, Québec, Canada
- Department of Metabolism, Vascular and Renal Health Axis, Laval University Hospital Research Center, Québec, Québec, Canada
- Corresponding author: André Marette,
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153
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Harcourt BE, Forbes JM, Matthews VB. Obesity-induced renal impairment is exacerbated in interleukin-6-knockout mice. Nephrology (Carlton) 2012; 17:257-62. [PMID: 22128916 DOI: 10.1111/j.1440-1797.2011.01547.x] [Citation(s) in RCA: 7] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/04/2023]
Abstract
AIM Interleukin-6 (IL-6) is secreted from adipose tissue and thought to contribute to obesity-related disorders. The aim of this study was to assess if IL-6-knockout (IL-6-/-) mice would develop obesity-induced renal impairment. METHODS Wild-type (WT) and IL-6-/- mice were high-fat fed (HFF) for 16 weeks to induce obesity. At the end of the study, renal function was measured via albumin/creatinine ratio and serum creatinine levels, using enzyme-linked immunosorbent assay (ELISA) and high-performance liquid chromatography (HPLC). Glomerulosclerotic index (GSI) was scored in periodic acid Schiff-stained sections and collagen IV accumulation was assessed by immunohistochemistry. Renal cortical tumour growth factor beta (TGF-β(1) ) activity and monocyte chemotactic protein-1 (MCP-1) levels were measured via ELISA. RESULTS Renal IL-6 concentrations were increased with obesity. Although both WT HFF and IL-6-/- HFF mice exhibited renal impairment as measured by increased serum creatinine and urinary albumin/creatinine ratios, this was exacerbated in IL-6-/- mice. Obese mice had renal activation of cortical TGF-β(1) , which was also higher in IL-6-/- mice. Collagen IV staining was not affected by obesity. GSI was increased with obesity in both WT and IL-6-/- mice. CONCLUSION Obese IL-6-/- mice demonstrated renal functional and structural abnormalities above that seen in obese WT mice. We suggest that absence or low IL-6 levels may be an important accelerating factor implicated in the development and progression of obesity-induced renal disease.
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Affiliation(s)
- Brooke E Harcourt
- Glycation and Diabetes Complications, Monash University, Melbourne, Victoria, Australia.
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154
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Terra R, Silva SAGD, Pinto VS, Dutra PML. Efeito do exercício no sistema imune: resposta, adaptação e sinalização celular. REV BRAS MED ESPORTE 2012. [DOI: 10.1590/s1517-86922012000300015] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/22/2022] Open
Abstract
INTRODUÇÃO: Durante o último século, o homem tornou-se menos ativo fisicamente, adotando hábitos cada vez mais sedentários. Isto promoveu aumento na incidência de doenças crônicas tais como doenças cardiovasculares, diabetes do tipo 2 e síndrome metabólica. A prática de atividade física pode influenciar o estado de higidez alterando estados metabólicos e também o sistema imunológico. OBJETIVO: Revisar na literatura estudos que abordem os efeitos promovidos pelo exercício físico no desenvolvimento da resposta imunológica e suas possíveis vias de transdução de sinais. MÉTODOS: Foram consultadas as bases de dados SciELO e PubMed. RESULTADOS: A literatura disponível mostra que durante a prática de exercício, várias subpopulações de leucócitos são alteradas de acordo com a intensidade e duração da atividade desempenhada. Exercícios de intensidade moderada estimulam uma resposta pró-inflamatória, enquanto aqueles de alta intensidade tendem a promover respostas anti-inflamatórias visando diminuir os danos na musculatura esquelética. Tais alterações são vistas em células apresentadoras de antígeno (como macrófagos e células dendríticas), neutrófilos, células natural killers (NK) e em moléculas de superfície como os receptores do tipo Toll (TLR) e do complexo principal de histocompatibilidade de classe II (MHC II), além das modificações promovidas em todo o repertório de citocinas. CONCLUSÃO: O estado atual do conhecimento permite considerar que as alterações no sistema imune são dependentes dos parâmetros inerentes ao exercício e que para que todas estas alterações ocorram, algumas cascatas de sinalização celular são acionadas, dando origem a um complexo processo de fosforilação/desfosforilação que culmina em ativação de fatores de transcrição, tradução de RNAm, síntese proteica e proliferação celular.
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155
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Garbers C, Hermanns HM, Schaper F, Müller-Newen G, Grötzinger J, Rose-John S, Scheller J. Plasticity and cross-talk of interleukin 6-type cytokines. Cytokine Growth Factor Rev 2012; 23:85-97. [PMID: 22595692 DOI: 10.1016/j.cytogfr.2012.04.001] [Citation(s) in RCA: 279] [Impact Index Per Article: 23.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/02/2012] [Accepted: 04/06/2012] [Indexed: 02/07/2023]
Abstract
Interleukin (IL)-6-type cytokines are critically involved in health and disease. The duration and strength of IL-6-type cytokine-mediated signaling is tightly regulated to avoid overshooting activities. Here, molecular mechanisms of inter-familiar cytokine cross-talk are reviewed which regulate dynamics and strength of IL-6 signal transduction. Both plasticity and cytokine cross-talk are significantly involved in pro- and anti-inflammatory/regenerative properties of IL-6-type cytokines. Furthermore, we focus on IL-6-type cytokine/cytokine receptor plasticity and cross-talk exemplified by the recently identified composite cytokines IL-30/IL-6R and IL-35, the first inter-familiar IL-6/IL-12 family member. The complete understanding of the intra- and extracellular cytokine networks will aid to develop novel tailor-made therapeutic strategies with reduced side effects.
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Affiliation(s)
- Christoph Garbers
- Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine University, Düsseldorf, Germany
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156
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Abstract
Lipid sensing and insulin signaling in the brain independently triggers a negative feedback system to lower glucose production and food intake. Here, we discuss the underlying molecular and neuronal mechanisms of lipid sensing and insulin signaling in the hypothalamus and how these mechanisms are affected in response to high-fat feeding. We propose that high-fat feeding concurrently disrupts hypothalamic insulin-signaling and lipid-sensing mechanisms and that experiments aimed to restore both insulin action and lipid sensing in the brain could effectively lower glucose production and food intake to restore metabolic homeostasis in type 2 diabetes and obesity.
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Affiliation(s)
- Jessica T Y Yue
- Toronto General Research Institute, University Health Network, Toronto, Canada
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157
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Kim YD, Kim YH, Cho YM, Kim DK, Ahn SW, Lee JM, Chanda D, Shong M, Lee CH, Choi HS. Metformin ameliorates IL-6-induced hepatic insulin resistance via induction of orphan nuclear receptor small heterodimer partner (SHP) in mouse models. Diabetologia 2012; 55:1482-94. [PMID: 22349108 DOI: 10.1007/s00125-012-2494-4] [Citation(s) in RCA: 51] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/23/2011] [Accepted: 01/09/2012] [Indexed: 01/14/2023]
Abstract
AIMS/HYPOTHESIS IL-6 is a proinflammatory cytokine associated with the pathogenesis of hepatic diseases. Metformin is an anti-diabetic drug used for the treatment of type 2 diabetes, and orphan nuclear receptor small heterodimer partner (SHP, also known as NR0B2), a transcriptional co-repressor, plays an important role in maintaining metabolic homeostasis. Here, we demonstrate that metformin-mediated activation of AMP-activated protein kinase (AMPK) increases SHP protein production and regulates IL-6-induced hepatic insulin resistance. METHODS We investigated metformin-mediated SHP production improved insulin resistance through the regulation of an IL-6-dependent pathway (involving signal transducer and activator of transcription 3 [STAT3] and suppressor of cytokine signalling 3 [SOCS3]) in both Shp knockdown and Shp null mice. RESULTS IL-6-induced STAT3 transactivation and SOCS3 production were significantly repressed by metformin, adenoviral constitutively active AMPK (Ad-CA-AMPK), and adenoviral SHP (Ad-SHP), but not in Shp knockdown, or with the adenoviral dominant negative form of AMPK (Ad-DN-AMPK). Chromatin immunoprecipitation (ChIP), co-immunoprecipitation (Co-IP) and protein localisation studies showed that SHP inhibits DNA binding of STAT3 on the Socs3 gene promoter via interaction and colocalisation within the nucleus. Upregulation of inflammatory genes and downregulation of hepatic insulin signalling by acute IL-6 treatment were observed in wild-type mice but not in Shp null mice. Finally, chronic IL-6 exposure caused hepatic insulin resistance, leading to impaired insulin tolerance and elevated gluconeogenesis, and these phenomena were aggravated in Shp null mice. CONCLUSIONS/INTERPRETATION Our results demonstrate that SHP upregulation by metformin may prevent hepatic disorders by regulating the IL-6-dependent pathway, and that this pathway can help to ameliorate the pathogenesis of cytokine-mediated metabolic dysfunction.
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Affiliation(s)
- Y D Kim
- National Creative Research Initiatives Center for Nuclear Receptor Signals, Hormone Research Center, School of Biological Sciences and Technology, Chonnam National University, Gwangju 500-757, Republic of Korea
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158
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Benrick A, Wallenius V, Asterholm IW. Interleukin-6 mediates exercise-induced increase in insulin sensitivity in mice. Exp Physiol 2012; 97:1224-35. [PMID: 22523382 DOI: 10.1113/expphysiol.2012.065508] [Citation(s) in RCA: 35] [Impact Index Per Article: 2.9] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/19/2022]
Abstract
Interleukin-6 (IL-6) is released from working skeletal muscle during exercise. We investigated the acute and the long-term beneficial effects of IL-6 on exercise-induced glucose uptake in skeletal muscle and insulin sensitivity. The acute effect on exercise-induced glucose uptake was measured in IL-6-deficient (IL-6(-/-)) mice and wild-type control animals using a tracer technique. There was no difference in serum disappearance of (3)[H]2-deoxyglucose after a single bout of exercise between IL-6(-/-) and wild-type mice (13565 ± 426 versus 14343 ± 1309 d.p.m. min ml(-1), P = 0.5). The glucose uptake rate in the extensor digitorum longus muscle was, however, lower in IL-6(-/-) compared with wild-type mice (398 ± 44 versus 657 ± 41 nmol g(-1) min(-1), P < 0.01). In a long-term study, we monitored insulin sensitivity, serum retinol-binding protein-4 (RBP-4) levels, running activity, food intake, body weight and body composition in IL-6(-/-) and wild-type mice on a high-fat diet (HFD), with or without access to running wheels. In sedentary IL-6(-/-) and wild-type mice, the HFD decreased insulin sensitivity (glucose area under the concentration-time curve increased about 20% during an insulin tolerance test, P < 0.05 for both genotypes versus baseline) and led to a 30% increase in serum RBP-4 levels (P < 0.01 for both genotypes versus baseline). Wild-type mice with access to running wheels were protected against these effects of the HFD and maintained their baseline insulin sensitivity and serum RBP-4 levels. In contrast, IL-6(-/-) mice did not benefit from running to the same extent as wild-type animals. The IL-6(-/-) mice with access to running wheels had a similar decrease in insulin sensitivity to their sedentary littermates (glucose area under the concentration-time curve during an insulin tolerance test in runners versus sedentary IL-6(-/-) HFD mice, 312 ± 14 versus 340 ± 22 mmol min l(-1), P = 0.4) and displayed a 14% increase in serum RBP-4 compared with baseline levels (P < 0.01). Our results indicate that endogenous IL-6 contributes to the exercise-induced increase in insulin sensitivity, but plays only a minor role for glucose uptake into skeletal muscle during exercise.
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Affiliation(s)
- Anna Benrick
- Institute of Neuroscience and Physiology/ Endocrinology, The Sahlgrenska Academy at the University of Gothenburg, Medicinaregatan 11, SE-405 30 Gothenburg, Sweden
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159
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Abstract
During the past decade, skeletal muscle has been identified as a secretory organ. Accordingly, we have suggested that cytokines and other peptides that are produced, expressed and released by muscle fibres and exert either autocrine, paracrine or endocrine effects should be classified as myokines. The finding that the muscle secretome consists of several hundred secreted peptides provides a conceptual basis and a whole new paradigm for understanding how muscles communicate with other organs, such as adipose tissue, liver, pancreas, bones and brain. However, some myokines exert their effects within the muscle itself. Thus, myostatin, LIF, IL-6 and IL-7 are involved in muscle hypertrophy and myogenesis, whereas BDNF and IL-6 are involved in AMPK-mediated fat oxidation. IL-6 also appears to have systemic effects on the liver, adipose tissue and the immune system, and mediates crosstalk between intestinal L cells and pancreatic islets. Other myokines include the osteogenic factors IGF-1 and FGF-2; FSTL-1, which improves the endothelial function of the vascular system; and the PGC-1α-dependent myokine irisin, which drives brown-fat-like development. Studies in the past few years suggest the existence of yet unidentified factors, secreted from muscle cells, which may influence cancer cell growth and pancreas function. Many proteins produced by skeletal muscle are dependent upon contraction; therefore, physical inactivity probably leads to an altered myokine response, which could provide a potential mechanism for the association between sedentary behaviour and many chronic diseases.
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Affiliation(s)
- Bente K Pedersen
- The Centre of Inflammation and Metabolism, Department of Infectious Diseases and CMRC, Rigshospitalet, Section 7641, Faculty of Health Sciences, University of Copenhagen, Blegdamsvej 9, DK-2100, Copenhagen, Denmark.
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160
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Ling J, Chaba T, Zhu LF, Jacobs RL, Vance DE. Hepatic ratio of phosphatidylcholine to phosphatidylethanolamine predicts survival after partial hepatectomy in mice. Hepatology 2012; 55:1094-102. [PMID: 22095799 DOI: 10.1002/hep.24782] [Citation(s) in RCA: 72] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 08/26/2011] [Accepted: 10/11/2011] [Indexed: 01/12/2023]
Abstract
UNLABELLED A major predictor of failed liver resection and transplantation is nonalcoholic fatty liver disease (NAFLD). NAFLD is linked to a wide spectrum of diseases including obesity and diabetes that are increasingly prevalent in Western populations. Thus, it is important to develop therapies aimed at improving posthepatectomy outcomes in patients with NAFLD, as well as to improve the evaluation of patients slated for hepatic surgery. Decreased hepatic phosphatidylcholine (PC) content and decreased ratio of hepatic PC to phosphatidylethanolamine (PE) have previously been linked to NAFLD. To determine if decreased hepatic PC/PE could predict survival after hepatectomy, we used mouse models lacking key enzymes in PC biosynthesis, namely, phosphatidylethanolamine N-methyltransferase and hepatic-specific CTP:phosphocholine cytidylyltransferase α. These mice were fed a high-fat diet to induce NAFLD. We then performed a 70% partial hepatectomy and monitored postoperative survival. We identified hepatic PC/PE to be inversely correlated with the development of steatosis and inflammation in the progression of NAFLD. Decreased hepatic PC/PE before surgery was also strongly associated with decreased rates of survival after partial hepatectomy. Choline supplementation to the diet increased hepatic PC/PE in Pemt(-/-) mice with NAFLD, decreased inflammation, and increased the survival rate after partial hepatectomy. CONCLUSION Decreased hepatic PC/PE is a predictor of NAFLD and survival following partial hepatectomy. Choline supplementation may serve as a potential therapy to prevent the progression of NAFLD and to improve postoperative outcome after liver surgery.
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Affiliation(s)
- Ji Ling
- Group on the Molecular and Cell Biology of Lipids, Department of Biochemistry, University of Alberta, Edmonton, AB, Canada
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161
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Wunderlich CM, Delić D, Behnke K, Meryk A, Ströhle P, Chaurasia B, Al-Quraishy S, Wunderlich F, Brüning JC, Wunderlich FT. Cutting edge: Inhibition of IL-6 trans-signaling protects from malaria-induced lethality in mice. THE JOURNAL OF IMMUNOLOGY 2012; 188:4141-4. [PMID: 22467660 DOI: 10.4049/jimmunol.1102137] [Citation(s) in RCA: 33] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Circulating IL-6 levels correlate with the severity of blood-stage malaria in humans and mouse models, but the impact of IL-6 classic signaling through membrane IL-6Rα, as well as IL-6 trans-signaling through soluble IL-6Rα, on the outcome of malaria has remained unknown. In this study, we created IL-6Rα-deficient mice that exhibit a 50% survival of otherwise lethal blood-stage malaria of the genus Plasmodium chabaudi. Inducing IL-6 trans-signaling by injection of mouse recombinant soluble IL-6Rα in IL-6Rα-deficient mice restores the lethal outcome to malaria infection. In contrast, inhibition of IL-6 trans-signaling via injection of recombinant sGP130Fc protein in control mice results in a 40% survival rate. Our data demonstrate that IL-6 trans-signaling, rather than classic IL-6 signaling, contributes to malaria-induced lethality in mice, preceded by an increased inflammatory response. Therefore, inhibition of IL-6 trans-signaling may serve as a novel promising therapeutic basis to combat malaria.
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Affiliation(s)
- Claudia M Wunderlich
- Center of Molecular Medicine Cologne, Excellence Cluster on Cellular Stress Responses in Aging-Associated Diseases, Institute for Genetics Cologne, Max Planck Institute for Neurological Research Cologne, D-50931 Cologne, Germany
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162
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Tarantino G, Finelli C, Colao A, Capone D, Tarantino M, Grimaldi E, Chianese D, Gioia S, Pasanisi F, Contaldo F, Scopacasa F, Savastano S. Are hepatic steatosis and carotid intima media thickness associated in obese patients with normal or slightly elevated gamma-glutamyl-transferase? J Transl Med 2012; 10:50. [PMID: 22424154 PMCID: PMC3342159 DOI: 10.1186/1479-5876-10-50] [Citation(s) in RCA: 39] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2011] [Accepted: 03/16/2012] [Indexed: 02/06/2023] Open
Abstract
BACKGROUND Hepatic steatosis (HS) has been associated with obesity and metabolic syndrome (MS), conditions carrying a high risk of coronary artery disease. We aimed to determine whether HS was an independent factor of atherogenic risk beyond its association with MS and its components. METHODS We assessed the circulating levels of the heat shock protein-70 (HSP-70), a chaperone involved in inflammation, endoplasmic reticulum stress and apoptosis at liver and endothelial level and the gamma-glutamyl transferase activity (γ-GT) correlating them to carotid intima-media thickness (IMT), along with lipid profile, HOMA, C-reactive protein, fibrinogen, ferritin, adiposity type as well as spleen volume in 52 obese pts with grade 1, 128 with grade 2, and 20 with grade 3 of HS evaluated by sonography. RESULTS Patients with different grade of HS demonstrated overlapping HSP-70 levels; similarly performed obese subjects regarding IMT. Using multiple regression analysis, IMT was predicted by age, visceral adiposity and by HOMA (β = 0.50, p < 0.0001, β = 0.30, p = 0.01 and β = 0.18, p = 0.048 respectively, while the severity of HS was predicted by visceral and subcutaneous adiposity and HOMA (β = 0.50, p < 0.0001 and β = 0.27, p = 0.001 and β = 0.18, p = 0.024, respectively). CONCLUSION In our series of patients with normal or mild elevation of γ-GT, the severity of HS does not entail higher IMT, which may be linked to MS stigmata.
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Affiliation(s)
- Giovanni Tarantino
- Department of Clinical and Experimental Medicine, Federico II University Medical School of Naples, Naples, Italy
| | - Carmine Finelli
- Fondazione Stella Maris Mediterraneo, Centro di Riferimento Regionale dei Disturbi e Comportamenti Alimentari e del Peso, "G. Gioia", Chiaromonte, (PZ), Italy
| | - Annamaria Colao
- Department of Molecular and Clinical Endocrinology and Oncology, Endocrinology Section, Federico II University Medical School of Naples, Naples, Italy
| | - Domenico Capone
- Department of Neurosciences, Unit of Clinical Pharmacology, Federico II University Medical School of Naples, Naples, Italy
| | - Marianna Tarantino
- Department of Biomorphological and Functional Sciences, Federico II University Medical School of Naples, Naples, Italy
| | - Ernesto Grimaldi
- Department of Biochemistry and Medical Biotechnology, Federico II University Medical School of Naples, Naples, Italy
| | - Donato Chianese
- Department of Biochemistry and Medical Biotechnology, Federico II University Medical School of Naples, Naples, Italy
| | - Saverio Gioia
- Fondazione Stella Maris Mediterraneo, Centro di Riferimento Regionale dei Disturbi e Comportamenti Alimentari e del Peso, "G. Gioia", Chiaromonte, (PZ), Italy
| | - Fabrizio Pasanisi
- Department of Clinical and Experimental Medicine, Federico II University Medical School of Naples, Naples, Italy
| | - Franco Contaldo
- Department of Clinical and Experimental Medicine, Federico II University Medical School of Naples, Naples, Italy
| | - Francesco Scopacasa
- Department of Biochemistry and Medical Biotechnology, Federico II University Medical School of Naples, Naples, Italy
| | - Silvia Savastano
- Department of Molecular and Clinical Endocrinology and Oncology, Endocrinology Section, Federico II University Medical School of Naples, Naples, Italy
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Yekollu SK, Thomas R, O’Sullivan B. Targeting curcusomes to inflammatory dendritic cells inhibits NF-κB and improves insulin resistance in obese mice. Diabetes 2011; 60:2928-38. [PMID: 21885868 PMCID: PMC3198103 DOI: 10.2337/db11-0275] [Citation(s) in RCA: 66] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 01/01/2023]
Abstract
OBJECTIVE To determine whether and by what mechanism systemic delivery of curcumin-containing liposomes improves insulin resistance in the leptin deficient (ob/ob) mouse model of insulin resistance. RESEARCH DESIGN AND METHODS Insulin resistant ob/ob mice with steatosis were injected intraperitoneally with liposome nanoparticles, entrapping the nuclear factor-κB (NF-κB) inhibitor curcumin (curcusomes), and uptake in liver and adipose tissue was determined by flow cytometry. The effects of curcusomes on macrophage NF-κB activation and cytokine production were assessed. Transfer experiments determined the role of hepatic tumor necrosis factor (TNF)/inducible nitric oxide synthase-producing dendritic cells (Tip-DCs) and adipose tissue macrophages (ATMs) in inflammation-induced insulin resistance, determined by homeostatic assessment of insulin resistance. RESULTS Phagocytic myeloid cells infiltrating the liver in ob/ob mice had the phenotypic characteristics of Tip-DCs that arise from monocyte precursors in the liver and spleen after infection. Targeting Tip-DCs and ATMs with curcusomes in ob/ob mice reduced NF-κB/RelA DNA binding activity, reduced TNF, and enhanced interleukin-4 production. Curcusomes improved peripheral insulin resistance. CONCLUSIONS Both hepatic Tip-DCs and ATMs contribute to insulin resistance in ob/ob mice. Curcusome nanoparticles inhibit proinflammatory pathways in hepatic Tip-DCs and ATMs and reverse insulin resistance. Targeting inflammatory DCs is a novel approach for type 2 diabetes treatment.
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Clementi AH, Gaudy AM, Zimmers TA, Koniaris LG, Mooney RA. Deletion of interleukin-6 improves pyruvate tolerance without altering hepatic insulin signaling in the leptin receptor-deficient mouse. Metabolism 2011; 60:1610-9. [PMID: 21632071 PMCID: PMC3166542 DOI: 10.1016/j.metabol.2011.04.004] [Citation(s) in RCA: 8] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 11/04/2010] [Revised: 04/07/2011] [Accepted: 04/16/2011] [Indexed: 02/06/2023]
Abstract
Obesity is associated with increased circulating interleukin-6 (IL-6), which may contribute to hepatic insulin resistance by impairing insulin receptor signaling. This study was designed to assess the impact of the systemic absence of IL-6 on the development of insulin resistance and glucose intolerance in an obese mouse model. Systemic insulin, glucose, and pyruvate tolerance tests were performed in IL-6 knockout (IL6KO) mice that had been crossed with a genetically obese (leptin receptor-deficient mouse model [Lep(db)]) mouse model. Real-time reverse transcriptase polymerase chain reaction and Western blot analysis assessed cellular and molecular markers of insulin signaling, inflammation, and metabolism. Absence of IL-6 did not improve systemic glucose or insulin tolerance, but Lep(db) × IL6KO mice displayed a smaller blood glucose increase following a pyruvate challenge. These results suggest that loss of IL-6 in the context of obesity may locally reduce hepatic glucose production from a gluconeogenic precursor. Hepatic insulin-dependent insulin receptor autophosphorylation, Akt activation, and FoxO1 phosphorylation were similar between Lep(db) × IL6KO mice and Lep(db) controls. Basal gene expression of the gluconeogenic enzyme phosphoenolpyruvate carboxykinase was reduced in male Lep(db) × IL6KO mice relative to Lep(db) controls; but gene expression of another regulatory enzyme, glucose-6-phosphatase, remained unaltered. Absence of IL-6 reduced gene expression of serum amyloid A and RelA in female Lep(db) mice, but did not alter hepatic triglyceride accumulation or lipogenic gene expression. Overall, our results suggest that IL-6 may be detrimental in obesity by contributing to elevated hepatic glucose output.
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Affiliation(s)
- Alicia H. Clementi
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY
| | - Allison M. Gaudy
- Department of Pharmacology and Physiology, University of Rochester Medical Center
| | - Teresa A. Zimmers
- Department of Cell Biology and Anatomy, University of Miami Miller School of Medicine, Miami FL
- Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida
| | - Leonidas G. Koniaris
- Department of Cell Biology and Anatomy, University of Miami Miller School of Medicine, Miami FL
- Department of Surgery, University of Miami Miller School of Medicine, Miami, Florida
| | - Robert A. Mooney
- Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, Rochester, NY
- Corresponding author: Department of Pathology and Laboratory Medicine, University of Rochester Medical Center, 601 Elmwood Ave., Rochester, NY 14642, , Tel: 585-275-7811 Fax: 585-756-4468
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165
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Pini M, Rhodes DH, Fantuzzi G. Hematological and acute-phase responses to diet-induced obesity in IL-6 KO mice. Cytokine 2011; 56:708-16. [PMID: 21996012 DOI: 10.1016/j.cyto.2011.09.015] [Citation(s) in RCA: 28] [Impact Index Per Article: 2.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/25/2011] [Revised: 09/06/2011] [Accepted: 09/19/2011] [Indexed: 02/08/2023]
Abstract
Obesity is associated with chronic inflammation and elevated levels of IL-6. The role of IL-6 in induction of acute-phase proteins and modulation of hematological responses has been demonstrated in models of inflammation and aging, but not in obesity. We hypothesized that IL-6 is necessary to regulate the acute-phase response and hematological changes associated with diet-induced obesity (DIO) in mice. Feeding a 60%kcal/fat diet for 13 weeks to C57BL6 WT male mice induced a significant increase in IL-6 expression in visceral adipose tissue (VAT), but not liver, compared to mice fed chow diet. Significantly elevated IL-6 levels were present in the peritoneal lavage fluid, but not plasma, of DIO compared to lean mice. A comparable degree of obesity, hepatomegaly, hyperleptinemia, VAT inflammation and insulin resistance was observed in DIO WT and IL-6 KO mice compared to WT and KO mice fed chow diet. Significant leukocytosis was observed in DIO WT but not DIO KO mice compared to lean groups. A significant reduction in platelet counts, without alterations in platelet size, percentage of circulating reticulated platelets and number of bone marrow megakaryocytes, was present in DIO KO mice compared to each other group. Hepatic expression of thrombopoietin was comparable in each group, with DIO WT and KO mice having reduced VAT expression compared to lean mice. Lean KO mice had significantly elevated plasma levels of thrombopoietin compared to each other group, whereas liver-associated thrombopoietin levels were comparable in each group. Deficiency of IL-6 resulted in blunted hepatic induction of the acute-phase protein serum amyloid A-1, whereas expression of hepcidin-1 and -2, LPS-binding protein, ceruloplasmin, plasminogen activator inhibitor-1 and thrombospondin-1 was IL-6-independent. In conclusion, in the absence of overt metabolic alterations, IL-6 modulates leukocytosis, thrombopoiesis and induction of SAA-1, but not other acute-phase proteins in obese mice.
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Affiliation(s)
- Maria Pini
- Department of Kinesiology and Nutrition, University of Illinois at Chicago, Chicago, IL 60612, United States
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166
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Wong N, Fam BC, Cempako GR, Steinberg GR, Walder K, Kay TW, Proietto J, Andrikopoulos S. Deficiency in interferon-gamma results in reduced body weight and better glucose tolerance in mice. Endocrinology 2011; 152:3690-9. [PMID: 21791564 DOI: 10.1210/en.2011-0288] [Citation(s) in RCA: 55] [Impact Index Per Article: 4.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/19/2022]
Abstract
Obesity is a chronic low-grade inflammatory disease caused by increased energy intake and reduced energy expenditure. Studies using animal models with deletion of inflammatory cytokines have produced conflicting results with some showing increased weight gain and others showing no effect or even reduced body weights. Clearly, more work is necessary to understand the role of cytokines on body weight control. The aim of this study was to determine the effect of interferon-γ deletion (IFNγ(-/-)) on body weight regulation and glucose metabolism. Male IFNγ(-/-) and wild-type C57BL/6 mice were fed a low-fat chow diet, and body weight, food intake, and energy expenditure were monitored over 20 wk. At the end of the study, ip glucose tolerance test, insulin tolerance test, basal glucose turnover, and hyperinsulinemic/euglycemic clamps were performed. Expression levels of arcuate nucleus neuropeptide Y, Agouti-related peptide, and proopiomelanocortin mRNA as well as circulating leptin levels were also determined. IFNγ(-/-) mice had improved glucose tolerance with reduced rate of glucose appearance and increased insulin sensitivity due to greater suppression of endogenous glucose output, which was associated with decreased hepatic glucose-6-phosphatase activity. In addition, we also observed reduced body weight associated with decreased food intake and increased physical activity. Neuropeptide Y and Agouti-related peptide mRNA expression was reduced, whereas proopiomelanocortin mRNA expression was increased, as were plasma leptin levels. Global deletion of IFNγ in mice resulted in reduced body weight associated with negative energy balance, improved glucose tolerance, and hepatic insulin sensitivity. Our findings demonstrate that IFNγ plays a critical role in the regulation of body weight and glucose metabolism.
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Affiliation(s)
- Nicole Wong
- University of Melbourne, Department of Medicine (Austin Health and Northern Health), Heidelberg Repatriation Hospital, 300 Waterdale Road, Heidelberg Heights, Victoria 3081, Australia.
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167
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Miller AM, Wang H, Bertola A, Park O, Horiguchi N, Ki SH, Yin S, Lafdil F, Gao B. Inflammation-associated interleukin-6/signal transducer and activator of transcription 3 activation ameliorates alcoholic and nonalcoholic fatty liver diseases in interleukin-10-deficient mice. Hepatology 2011; 54:846-56. [PMID: 21725996 PMCID: PMC3197882 DOI: 10.1002/hep.24517] [Citation(s) in RCA: 135] [Impact Index Per Article: 10.4] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 12/11/2022]
Abstract
UNLABELLED Alcoholic and nonalcoholic steatohepatitis are characterized by fatty liver plus inflammation. It is generally believed that steatosis promotes inflammation, whereas inflammation in turn aggregates steatosis. Thus, we hypothesized the deletion of interleukin (IL)-10, a key anti-inflammatory cytokine, exacerbates liver inflammation, steatosis, and hepatocellular damage in alcoholic and nonalcoholic fatty liver disease models that were achieved via feeding mice with a liquid diet containing 5% ethanol for 4 weeks or a high-fat diet (HFD) for 12 weeks, respectively. IL-10 knockout (IL-10(-/-)) mice and several other strains of genetically modified mice were generated and used. Compared with wild-type mice, IL-10(-/-) mice had greater liver inflammatory response with higher levels of IL-6 and hepatic signal transducer and activator of transcription 3 (STAT3) activation, but less steatosis and hepatocellular damage after alcohol or HFD feeding. An additional deletion of IL-6 or hepatic STAT3 restored steatosis and hepatocellular damage but further enhanced liver inflammatory response in IL-10(-/-) mice. In addition, the hepatic expression of sterol regulatory element-binding protein 1 and key downstream lipogenic proteins and enzymes in fatty acid synthesis were down-regulated in IL-10(-/-) mice. Conversely, IL-10(-/-) mice displayed enhanced levels of phosphorylated adenosine monophosphate-activated protein kinase and its downstream targets including phosphorylated acetyl-coenzyme A carboxylase and carnitine palmitoyltransferase 1 in the liver. Such dysregulations were corrected in IL-10(-/-) IL-6(-/-) or IL-10(-/-) STAT3(Hep-/-) double knockout mice. CONCLUSION IL-10(-/-) mice are prone to liver inflammatory response but are resistant to steatosis and hepatocellular damage induced by ethanol or HFD feeding. Resistance to steatosis in these mice is attributable to elevation of inflammation-associated hepatic IL-6/STAT3 activation that subsequently down-regulates lipogenic genes but up-regulates fatty acid oxidation-associated genes in the liver.
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Affiliation(s)
- Andrew M. Miller
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Hua Wang
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Adeline Bertola
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Ogyi Park
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
| | - Norio Horiguchi
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
- Department of Medicine and Molecular Science, Gunma University Graduate School of Medicine, Gunma 371-8511, Japan
| | - Sung Hwan Ki
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
- Laboratory of Toxicology, College of Pharmacy, Chosun University, Gwangju 501-759, South Korea
| | - Shi Yin
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
- Institute of Clinical Pharmacology, Anhui Medical University, Hefei, Anhui 230032, China
| | - Fouad Lafdil
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
- INSERM, U955, Créteil, F-94000 France
- Université Paris-Est, Faculté de Médecine, UMR-S955, Créteil, F-94000 France
| | - Bin Gao
- Laboratory of Liver Diseases, National Institute on Alcohol Abuse and Alcoholism, National Institutes of Health, Bethesda, MD 20892, USA
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168
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Jones SA, Scheller J, Rose-John S. Therapeutic strategies for the clinical blockade of IL-6/gp130 signaling. J Clin Invest 2011; 121:3375-83. [PMID: 21881215 PMCID: PMC3163962 DOI: 10.1172/jci57158] [Citation(s) in RCA: 541] [Impact Index Per Article: 41.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
The successful treatment of certain autoimmune conditions with the humanized anti-IL-6 receptor (IL-6R) antibody tocilizumab has emphasized the clinical importance of cytokines that signal through the β-receptor subunit glycoprotein 130 (gp130). In this Review, we explore how gp130 signaling controls disease progression and examine why IL-6 has a special role among these cytokines as an inflammatory regulator. Attention will be given to the role of the soluble IL-6R, and we will provide a perspective into the clinical blockade of IL-6 activity in autoimmunity, inflammation, and cancer.
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Affiliation(s)
- Simon A. Jones
- Department of Infection, Immunity and Biochemistry, The School of Medicine, Cardiff University, Cardiff, United Kingdom.
Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany.
Institute of Biochemistry, Christian-Albrechts-University, Kiel, Germany
| | - Jürgen Scheller
- Department of Infection, Immunity and Biochemistry, The School of Medicine, Cardiff University, Cardiff, United Kingdom.
Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany.
Institute of Biochemistry, Christian-Albrechts-University, Kiel, Germany
| | - Stefan Rose-John
- Department of Infection, Immunity and Biochemistry, The School of Medicine, Cardiff University, Cardiff, United Kingdom.
Institute of Biochemistry and Molecular Biology II, Medical Faculty, Heinrich-Heine-University, Düsseldorf, Germany.
Institute of Biochemistry, Christian-Albrechts-University, Kiel, Germany
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169
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Affiliation(s)
- Norbert Stefan
- Department of Internal Medicine IV, Division of Endocrinology, Diabetology, Vascular Medicine, Nephrology and Clinical Chemistry, University of Tübingen, Tübingen, Germany.
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170
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Frisdal E, Lesnik P, Olivier M, Robillard P, Chapman MJ, Huby T, Guerin M, Le Goff W. Interleukin-6 protects human macrophages from cellular cholesterol accumulation and attenuates the proinflammatory response. J Biol Chem 2011; 286:30926-30936. [PMID: 21757719 DOI: 10.1074/jbc.m111.264325] [Citation(s) in RCA: 81] [Impact Index Per Article: 6.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2022] Open
Abstract
Cholesterol-laden monocyte-derived macrophages are phagocytic cells characteristic of early and advanced atherosclerotic lesions. Interleukin-6 (IL-6) is a macrophage secretory product that is abundantly expressed in atherosclerotic plaques but whose precise role in atherogenesis is unclear. The capacity of macrophages to clear apoptotic cells, through the efferocytosis mechanism, as well as to reduce cellular cholesterol accumulation contributes to prevent plaque progression and instability. By virtue of its capacity to promote cellular cholesterol efflux from phagocyte-macrophages, ABCA1 was reported to reduce atherosclerosis. We demonstrated that lipid loading in human macrophages was accompanied by a strong increase of IL-6 secretion. Interestingly, IL-6 markedly induced ABCA1 expression and enhanced ABCA1-mediated cholesterol efflux from human macrophages to apoAI. Stimulation of ABCA1-mediated cholesterol efflux by IL-6 was, however, abolished by selective inhibition of the Jak-2/Stat3 signaling pathway. In addition, we observed that the expression of molecules described to promote efferocytosis, i.e. c-mer proto-oncogene-tyrosine kinase, thrombospondin-1, and transglutaminase 2, was significantly induced in human macrophages upon treatment with IL-6. Consistent with these findings, IL-6 enhanced the capacity of human macrophages to phagocytose apoptotic cells; moreover, we observed that IL-6 stimulates the ABCA1-mediated efflux of cholesterol derived from the ingestion of free cholesterol-loaded apoptotic macrophages. Finally, the treatment of human macrophages with IL-6 led to the establishment of an anti-inflammatory cytokine profile, characterized by an increased secretion of IL-4 and IL-10 together with a decrease of that of IL-1β. Taken together, our results indicate that IL-6 favors the elimination of excess cholesterol in human macrophages and phagocytes by stimulation of ABCA1-mediated cellular free cholesterol efflux and attenuates the macrophage proinflammatory phenotype. Thus, high amounts of IL-6 secreted by lipid laden human macrophages may constitute a protective response from macrophages to prevent accumulation of cytotoxic-free cholesterol. Such a cellular recycling of free cholesterol may contribute to reduce both foam cell formation and the accumulation of apoptotic bodies as well as intraplaque inflammation in atherosclerotic lesions.
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Affiliation(s)
- Eric Frisdal
- INSERM, UMR_S939, Dyslipidemia, Inflammation, and Atherosclerosis in Metabolic Diseases, and the ICAN Institute of CardioMetabolism and Nutrition F-75013 and the Université Pierre et Marie Curie Paris 06, UMR_S939, F-75005, Paris, France
| | - Philippe Lesnik
- INSERM, UMR_S939, Dyslipidemia, Inflammation, and Atherosclerosis in Metabolic Diseases, and the ICAN Institute of CardioMetabolism and Nutrition F-75013 and the Université Pierre et Marie Curie Paris 06, UMR_S939, F-75005, Paris, France
| | - Maryline Olivier
- INSERM, UMR_S939, Dyslipidemia, Inflammation, and Atherosclerosis in Metabolic Diseases, and the ICAN Institute of CardioMetabolism and Nutrition F-75013 and the Université Pierre et Marie Curie Paris 06, UMR_S939, F-75005, Paris, France
| | - Paul Robillard
- INSERM, UMR_S939, Dyslipidemia, Inflammation, and Atherosclerosis in Metabolic Diseases, and the ICAN Institute of CardioMetabolism and Nutrition F-75013 and the Université Pierre et Marie Curie Paris 06, UMR_S939, F-75005, Paris, France
| | - M John Chapman
- INSERM, UMR_S939, Dyslipidemia, Inflammation, and Atherosclerosis in Metabolic Diseases, and the ICAN Institute of CardioMetabolism and Nutrition F-75013 and the Université Pierre et Marie Curie Paris 06, UMR_S939, F-75005, Paris, France
| | - Thierry Huby
- INSERM, UMR_S939, Dyslipidemia, Inflammation, and Atherosclerosis in Metabolic Diseases, and the ICAN Institute of CardioMetabolism and Nutrition F-75013 and the Université Pierre et Marie Curie Paris 06, UMR_S939, F-75005, Paris, France
| | - Maryse Guerin
- INSERM, UMR_S939, Dyslipidemia, Inflammation, and Atherosclerosis in Metabolic Diseases, and the ICAN Institute of CardioMetabolism and Nutrition F-75013 and the Université Pierre et Marie Curie Paris 06, UMR_S939, F-75005, Paris, France
| | - Wilfried Le Goff
- INSERM, UMR_S939, Dyslipidemia, Inflammation, and Atherosclerosis in Metabolic Diseases, and the ICAN Institute of CardioMetabolism and Nutrition F-75013 and the Université Pierre et Marie Curie Paris 06, UMR_S939, F-75005, Paris, France.
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171
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Abstract
Obesity is a highly prevalent health problem in Western countries that leads to many important diseases such as type 2 diabetes and metabolic syndrome being now considered an inflammatory chronic disease. Adipocytes are no longer considered passive cells storing fat since they are major producers of inflammatory cytokines during obesity. Adipocytes and macrophages share many biological properties including the synthesis of similar molecules regulating inflammation. Fatty acid levels are elevated in obesity and induce inflammatory pathways by yet a mostly unknown mechanism, leading to the development of insulin and leptin resistance. Recent studies suggest that these effects could be mediated through the activation of toll-like receptors (TLR). TLR signalling pathways might contribute to the development of obesity-associated insulin resistance, thus representing a connection between innate immunity and metabolism. Here, we summarize the recent evidence for the important role that TLRs play in adipose tissue, obesity and insulin resistance.
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Affiliation(s)
- Manuel Fresno
- Centro de Biología Molecular Severo Ochoa, Consejo Superior de Investigaciones Cientificas, Universidad Autónoma de Madrid, Cantoblanco, 28049 Madrid, Spain.
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172
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Chaudhry A, Samstein RM, Treuting P, Liang Y, Pils MC, Heinrich JM, Jack RS, Wunderlich FT, Brüning JC, Müller W, Rudensky AY. Interleukin-10 signaling in regulatory T cells is required for suppression of Th17 cell-mediated inflammation. Immunity 2011; 34:566-78. [PMID: 21511185 DOI: 10.1016/j.immuni.2011.03.018] [Citation(s) in RCA: 687] [Impact Index Per Article: 52.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/08/2010] [Revised: 02/26/2011] [Accepted: 03/16/2011] [Indexed: 12/11/2022]
Abstract
Effector CD4+ T cell subsets, whose differentiation is facilitated by distinct cytokine cues, amplify the corresponding type of inflammatory response. Regulatory T (Treg) cells integrate environmental cues to suppress particular types of inflammation. In this regard, STAT3, a transcription factor essential for T helper 17 (Th17) cell differentiation, is necessary for Treg cell-mediated control of Th17 cell responses. Here, we showed that anti-inflammatory interleukin-10 (IL-10), and not proinflammatory IL-6 and IL-23 cytokine signaling, endowed Treg cells with the ability to suppress pathogenic Th17 cell responses. Ablation of the IL-10 receptor in Treg cells resulted in selective dysregulation of Th17 cell responses and colitis similar to that observed in mice harboring STAT3-deficient Treg cells. Thus, Treg cells limit Th17 cell inflammation by serving as principal amplifiers of negative regulatory circuits operating in immune effector cells.
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Affiliation(s)
- Ashutosh Chaudhry
- Howard Hughes Medical Institute and Immunology Program, Memorial Sloan-Kettering Cancer Center, New York, NY 10065, USA
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173
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The pro- and anti-inflammatory properties of the cytokine interleukin-6. BIOCHIMICA ET BIOPHYSICA ACTA-MOLECULAR CELL RESEARCH 2011; 1813:878-88. [PMID: 21296109 DOI: 10.1016/j.bbamcr.2011.01.034] [Citation(s) in RCA: 2184] [Impact Index Per Article: 168.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Subscribe] [Scholar Register] [Received: 12/10/2010] [Revised: 01/23/2011] [Accepted: 01/27/2011] [Indexed: 02/06/2023]
Abstract
Interleukin-6 is a cytokine not only involved in inflammation and infection responses but also in the regulation of metabolic, regenerative, and neural processes. In classic signaling, interleukin-6 stimulates target cells via a membrane bound interleukin-6 receptor, which upon ligand binding associates with the signaling receptor protein gp130. Gp130 dimerizes, leading to the activation of Janus kinases and subsequent phosphorylation of tyrosine residues within the cytoplasmic portion of gp130. This leads to the engagement of phosphatase Src homology domains containing tyrosin phosphatase-2 (SHP-2) and activation of the ras/raf/Mitogen-activated protein (MAP) kinase (MAPK) pathway. In addition, signal transducer and activator of transcription factors are recruited, which are phosphorylated, and consequently dimerize whereupon they translocate into the nucleus and activate target genes. Interestingly, only few cells express membrane bound interleukin-6 receptor whereas all cells display gp130 on the cell surface. While cells, which only express gp130, are not responsive to interleukin-6 alone, they can respond to a complex of interleukin-6 bound to a naturally occurring soluble form of the interleukin-6 receptor. Therefore, the generation of soluble form of the interleukin-6 receptor dramatically enlarges the spectrum of interleukin-6 target cells. This process has been named trans-signaling. Here, we review the involvement of both signaling modes in the biology of interleukin-6. It turns out that regenerative or anti-inflammatory activities of interleukin-6 are mediated by classic signaling whereas pro-inflammatory responses of interleukin-6 are rather mediated by trans-signaling. This is important since therapeutic blockade of interleukin-6 by the neutralizing anti-interleukin-6 receptor monoclonal antibody tocilizumab has recently been approved for the treatment of inflammatory diseases. This article is part of a Special Issue entitled: 11th European Symposium on Calcium.
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174
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Abstract
Components of the immune system are altered in obesity and type 2 diabetes (T2D), with the most apparent changes occurring in adipose tissue, the liver, pancreatic islets, the vasculature and circulating leukocytes. These immunological changes include altered levels of specific cytokines and chemokines, changes in the number and activation state of various leukocyte populations and increased apoptosis and tissue fibrosis. Together, these changes suggest that inflammation participates in the pathogenesis of T2D. Preliminary results from clinical trials with salicylates and interleukin-1 antagonists support this notion and have opened the door for immunomodulatory strategies for the treatment of T2D that simultaneously lower blood glucose levels and potentially reduce the severity and prevalence of the associated complications of this disease.
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175
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Baker RG, Hayden MS, Ghosh S. NF-κB, inflammation, and metabolic disease. Cell Metab 2011; 13:11-22. [PMID: 21195345 PMCID: PMC3040418 DOI: 10.1016/j.cmet.2010.12.008] [Citation(s) in RCA: 1424] [Impact Index Per Article: 109.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 07/12/2010] [Revised: 09/29/2010] [Accepted: 11/04/2010] [Indexed: 02/06/2023]
Abstract
Metabolic disorders including obesity, type 2 diabetes, and atherosclerosis have been viewed historically as lipid storage disorders brought about by overnutrition. It is now widely appreciated that chronic low-grade inflammation plays a key role in the initiation, propagation, and development of metabolic diseases. Consistent with its central role in coordinating inflammatory responses, numerous recent studies have implicated the transcription factor NF-κB in the development of such diseases, thereby further establishing inflammation as a critical factor in their etiology and offering hope for the development of new therapeutic approaches for their treatment.
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Affiliation(s)
- Rebecca G. Baker
- Department of Microbiology & Immunology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Matthew S. Hayden
- Department of Microbiology & Immunology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
| | - Sankar Ghosh
- Department of Microbiology & Immunology, College of Physicians and Surgeons, Columbia University, New York, NY 10032
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176
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Könner AC, Brüning JC. Toll-like receptors: linking inflammation to metabolism. Trends Endocrinol Metab 2011; 22:16-23. [PMID: 20888253 DOI: 10.1016/j.tem.2010.08.007] [Citation(s) in RCA: 245] [Impact Index Per Article: 18.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Received: 06/15/2010] [Revised: 08/25/2010] [Accepted: 08/25/2010] [Indexed: 02/06/2023]
Abstract
Obesity has been characterized as a state of chronic inflammation. Inflammatory signaling not only causes peripheral insulin resistance, but also promotes neuronal insulin and leptin resistance, which further propagates a positive energy balance. Upon development of obesity, numerous conditions, including increased circulating cytokine concentrations and cell autonomous dysregulation of homeostatic signaling pathways, such as the endoplasmic reticulum stress response, promote activation of stress kinases, to cause peripheral insulin as well as central insulin and leptin resistance. Recently, activation of toll-like receptor (TLR) signaling has been recognized as an alternative activator of obesity-induced inflammation. In this paper, we review recent progress in defining the molecular basis of obesity-associated TLR activation and its role in the development of metabolic syndrome.
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Affiliation(s)
- A Christine Könner
- Department of Mouse Genetics and Metabolism, Institute for Genetics, Cologne Excellence Cluster on Cellular Stress Responses in Aging Associated Diseases (CECAD), Center of Molecular Medicine Cologne (CMMC), University of Cologne and Max Planck Institute for the Biology of Ageing, D-50674 Cologne, Germany
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177
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Tamura Y, Watanabe K, Kantani T, Hayashi J, Ishida N, Kaneki M. Upregulation of circulating IL-15 by treadmill running in healthy individuals: is IL-15 an endocrine mediator of the beneficial effects of endurance exercise? Endocr J 2011; 58:211-5. [PMID: 21307608 DOI: 10.1507/endocrj.k10e-400] [Citation(s) in RCA: 94] [Impact Index Per Article: 7.2] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 11/23/2022] Open
Abstract
The beneficial effects of endurance exercise include insulin-sensitization and reduction of fat mass. Limited knowledge is available about the mechanisms by which endurance exercise exerts the salutary effects. Myokines, cytokines secreted by skeletal muscle, have been recognized as a potential mediator. Recently, a role of skeletal muscle-derived interleukin-15 (IL-15) in improvement of fat-lean body mass composition and insulin sensitivity has been proposed. Yet, previous studies have reported that endurance training does not increase production or secretion of IL-15 in skeletal muscle. Here, we show that in opposition to previous findings, 30-min treadmill running at 70% of age-predicted maximum heart rate resulted in a significant increase in circulating IL-15 level in untrained healthy young men. These findings suggest that IL-15 might play a role in the systemic anti-obesogenic and insulin-sensitizing effects of endurance exercise, not only as a paracrine and autocrine but also as an endocrine factor.
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Affiliation(s)
- Yoshiaki Tamura
- Department of Anesthesia, Critical Care, and Pain Medicine, Massachusetts General Hospital, Shriners Hospitals for Children, Harvard Medical School, Charlestown, MA 02129, USA
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