| 1. |
- Benrick, Anna, 1979, et al.
(författare)
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A non-conservative polymorphism in the IL-6 signal transducer (IL6ST)/gp130 is associated with myocardial infarction in a hypertensive population.
- 2008
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Ingår i: Regulatory peptides. - : Elsevier BV. - 0167-0115. ; 146:1-3, s. 189-96
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Tidskriftsartikel (refereegranskat)abstract
- Inflammation is a key component in the development of atherosclerosis, and myocardial infarction (MI); therefore we investigated the association between an interleukin-6 signal transducer (IL6ST)/gp130 polymorphism, gp130 function and risk of MI. Structural modeling suggested that a non-conservative single nucleotide polymorphism in the gp130, Gly148Arg, can change the stability and functional properties of the molecule. In vitro studies were done with BAF/3 cells lacking endogenous gp130. Cells stably transfected with the gp130 148Arg variant proliferated less and showed slightly lower STAT-3 phosphorylation in response to gp130 stimulation as compared to cells transfected with gp130 148Gly. In a prospectively followed hypertensive cohort we identified 167 patients who suffered a MI during the study and compared them to matched controls (mean age 57 years, 73% males, n=482). Carriers of the 148Arg variant (f(Arg)=0.12) of the gp130 receptor had decreased odds ratio for MI in univariate analysis (0.56, 95% CI 0.34-0.91, p=0.02). In conclusion, a genetically determined structural variant of the IL-6 receptor subunit gp130 is, independently of other known risk factors, associated with decreased risk of MI. The variant is also associated with decreased IL-6 responsiveness and could lead to a configuration change in the gp130 receptor.
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| 2. |
- Benrick, Anna, 1979
(författare)
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Cytokines in Metabolic Functions
- 2008
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- During infections, circulating cytokines are largely produced by immune cells. In healthy obese individuals, large parts of these circulating cytokines are produced in adipose tissue, for instance by macrophages that have accumulated there. The aim of this thesis was to investigate the role of cytokines, in particular interleukin-6 (IL-6), IL-1? and leukemia inhibitory factor (LIF), in the regulation of metabolism and body fat mass. Furthermore, we also wanted to examine the role of the IL-6 signal transducer (IL6ST)/gp130 receptor signalling. We have previously shown that IL-6 depleted (IL-6 -/-) mice develop late-onset obesity and we have now found a similar effect on IL-1 depletion. We have used IL-1 receptor type I depleted (IL-1RI -/-) mice to study the role of endogenous IL-1 on obesity, as measured by DEXA. The obesity in IL-1RI -/- was accompanied by decreased insulin and leptin sensitivity. Spontaneous locomotor activity and fat utilization, as measured in metabolic cages, were decreased in pre-obese IL-1RI -/- animals. At the hypothalamic level, deficiency of endogenous IL-1 activity in knockout mice was associated with enhanced expression of the obesity promoting peptides NPY and MCH, and decreased expression of the obesity suppressing peptide orexin. In IL-6 -/- mice, the expression of corticotrophin releasing hormone, a known stimulator of energy expenditure and the sympathetic nerve system, was decreased, as shown by RT-PCR. Moreover, endogenous IL-6 and IL-1? seemed to affect each others? expression in the hypothalamus. Therefore, IL-6 and IL-1 may interact in the CNS, presumably in the hypothalamus, to suppress fat mass, possibly by increasing energy expenditure and maybe especially fat burning. LIF is a member of the IL-6 receptor family, which shares the IL6ST/gp130, and has been reported to decrease obesity. We found that systemic LIF treatment could reduce white and brown fat depots in ovariectomized mice, suggesting that LIF can reduce obesity independently of estrogen signalling. Obesity and inflammation are key components in the development of atherosclerosis and myocardial infarction. We identified an association between an IL6ST/gp130 polymorphism in amino acid 148 (Gly/Arg) and risk of myocardial infarction in a hypertensive population. In vitro studies showed decreased proliferation and lower STAT-3 phosphorylation in cells transfected with gp130 148Arg compared to gp130 148Gly. Structural modelling suggested changes in the stability and functional properties of the gp130 148Arg molecule. The present results suggest that the cytokines IL-6, IL-1 and LIF are involved in the regulation of body fat mass and energy expenditure. The effects of IL-6 and IL-1 may be exerted at the CNS level and involve altered expression of hypothalamic peptides regulating fat mass and energy expenditure. This can constitute a possible mechanism contributing to the mature-onset obesity in IL-6 -/- and IL-1RI -/- mice. LIF may suppress obesity via estrogen independent effects in the periphery. In human subjects, the 148th amino acid arginine of the gp130 receptor is associated with decreased risk of myocardial infarction, possibly due to an impaired responsiveness to cytokines in the IL-6 receptor family.
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| 3. |
- Benrick, Anna, 1979, et al.
(författare)
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Interleukin-6 gene knockout influences energy balance regulating peptides in the hypothalamic paraventricular and supraoptic nuclei.
- 2009
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Ingår i: Journal of neuroendocrinology. - : Wiley. - 1365-2826 .- 0953-8194. ; 21:7, s. 620-8
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Tidskriftsartikel (refereegranskat)abstract
- Interleukin (IL)-6 is a pro-inflammatory cytokine that also affects metabolic function because IL-6 depleted (IL-6(-/-)) mice develop late-onset obesity. IL-6 appears to act in the central nervous system, presumably in the hypothalamus, to increase energy expenditure that appears to involve stimulation of the sympathetic nervous system. In the present study, we explored possible central mechanisms for the effects exerted by IL-6 on body fat. Therefore, we measured the effects of IL-6 depletion in IL-6(-/-) mice on expression of key hypothalamic peptide genes involved in energy balance by the real time polymerase chain reaction. Additionally, co-localisation between such peptides and IL-6 receptor alpha was investigated by immunohistochemistry. IL-6 deficiency decreased the expression of several peptides found in the paraventricular nucleus (PVN), which is a nucleus that has been attributed an adipostatic function. For example, corticotrophin-releasing hormone (CRH), which is reported to stimulate the sympathetic nervous system, was decreased by 40% in older IL-6(-/-) mice. Oxytocin, which is reported to prevent obesity, was also decreased in older IL-6(-/-) animals, as was arginine vasopressin (AVP). The IL-6 receptor alpha was abundantly expressed in the PVN, but also in the supraoptic nucleus, and was shown to be co-expressed to a high extent with CRH, AVP, oxytocin and thyrotrophin-releasing hormone. These data indicate that depletion of endogenous IL-6, a body fat suppressing cytokine, is associated with the decreased expression of CRH and oxytocin (i.e. energy balance regulating peptides) as well as AVP in the PVN. Because IL-6 receptor alpha is co-expressed with CRH, oxytocin and AVP, IL-6 could stimulate the expression of these peptides directly.
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| 4. |
- Shao, Linus Ruijin, 1964, et al.
(författare)
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Down-Regulation of Cilia-Localized IL-6R{alpha} by 17{beta}-Estradiol in Mouse and Human Fallopian Tubes.
- 2009
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Ingår i: American journal of physiology. Cell physiology. - : American Physiological Society. - 0363-6143 .- 1522-1563. ; 297:1
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Tidskriftsartikel (refereegranskat)abstract
- The action of Interleukin-6 (IL-6) impacts female reproduction. Although IL-6 was recently shown to inhibit cilia activity in human fallopian tubes in vitro, the molecular mechanisms underlying IL-6 signaling to tubal function remain elusive. Here, we investigate the cellular localization, regulation, and possible function of two IL-6 receptors (IL-6Ralpha and gp130) in mouse and human fallopian tubes in vivo. We show that IL-6Ralpha is restricted to the cilia of epithelial cells in both mouse and human fallopian tubes. Exogenous 17beta-estradiol (E2), but not progesterone (P4), causes a time-dependent decrease in IL-6Ralpha expression which is blocked by the estrogen receptor (ER) antagonist ICI 182,780. Exposure of different ER-selective agonists, PTT or DPN, demonstrated an ER subtype-specific regulation of IL-6Ralphaalpha in mouse fallopian tubes. In contrast to IL-6Ralpha, gp130 was detected in tubal epithelial cells in mice but not in humans. In humans, gp130 was found in the muscle cells and was decreased in the periovulatory and luteal phases during the reproductive cycles, indicating a species-specific expression and regulation of gp130 in the fallopian tube. Expression of tubal IL-6Ralpha and gp130 in IL-6 knockout mice was found to be normal; however, E2 treatment increased IL-6Ralpha, but not gp130, in IL-6 knockout mice compared to wild-type mice. Furthermore, expression levels of IL-6Ralpha, but not gp130, decreased in parallel with estrogenic accelerated oocyte-cumulus complex (OCC) transport in mouse fallopian tubes. Our findings unveil a potential role for cilia-specific IL-6Ralpha in the regulation of OCC transport and suggest an estrogen-regulatory pathway of IL-6Ralpha in the fallopian tube. Key words: estrogen, IL-6R, cilia, fallopian tube.
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| 5. |
- Strandberg, Louise, 1981, et al.
(författare)
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Mice chronically fed high-fat diet have increased mortality and disturbed immune response in sepsis.
- 2009
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Ingår i: PloS one. - : Public Library of Science (PLoS). - 1932-6203. ; 4:10
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Tidskriftsartikel (refereegranskat)abstract
- BACKGROUND: Sepsis is a potentially deadly disease that often is caused by gram-positive bacteria, in particular Staphylococcus aureus (S. aureus). As there are few effective therapies for sepsis, increased basic knowledge about factors predisposing is needed. METHODOLOGY/PRINCIPAL FINDINGS: The purpose of this study was to study the effect of Western diet on mortality induced by intravenous S. aureus inoculation and the immune functions before and after bacterial inoculation. Here we show that C57Bl/6 mice on high-fat diet (HFD) for 8 weeks, like genetically obese Ob/Ob mice on low-fat diet (LFD), have increased mortality during S. aureus-induced sepsis compared with LFD-fed C57Bl/6 controls. Bacterial load in the kidneys 5-7 days after inoculation was increased 10-fold in HFD-fed compared with LFD-fed mice. At that time, HFD-fed mice had increased serum levels and fat mRNA expression of the immune suppressing cytokines interleukin-1 receptor antagonist (IL-1Ra) and IL-10 compared with LFD-fed mice. In addition, HFD-fed mice had increased serum levels of the pro-inflammatory IL-1beta. Also, HFD-fed mice with and without infection had increased levels of macrophages in fat. The proportion and function of phagocytosing granulocytes, and the production of reactive oxygen species (ROS) by peritoneal lavage cells were decreased in HFD-fed compared with LFD-fed mice. CONCLUSIONS: Our findings imply that chronic HFD disturb several innate immune functions in mice, and impairs the ability to clear S. aureus and survive sepsis.
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