help button home button Endocrine Society JCEM
HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Journal of Clinical Endocrinology & Metabolism , doi:10.1210/jc.2005-2848
This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Pietiläinen, K. H.
Right arrow Articles by Yki-Järvinen, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Pietiläinen, K. H.
Right arrow Articles by Yki-Järvinen, H.
Related Collections
Right arrow Metabolism
Right arrow Obesity
The Journal of Clinical Endocrinology & Metabolism Vol. 91, No. 7 2776-2781
Copyright © 2006 by The Endocrine Society

Acquired Obesity Increases CD68 and Tumor Necrosis Factor-{alpha} and Decreases Adiponectin Gene Expression in Adipose Tissue: A Study in Monozygotic Twins

Kirsi H. Pietiläinen1, Katja Kannisto1, Elena Korsheninnikova, Aila Rissanen, Jaakko Kaprio, Ewa Ehrenborg, Anders Hamsten and Hannele Yki-Järvinen

Obesity Research Unit (K.H.P., A.R.), Department of Psychiatry, and Department of Medicine (K.H.P., H.Y.-J.), Division of Diabetes, Helsinki University Central Hospital, FIN-00290 Helsinki, Finland; The Finnish Twin Cohort Study (K.H.P., J.K.), Department of Public Health, University of Helsinki, 00014 Helsinki, Finland; Department of Medicine (K.K., E.E., A.H., H.Y.-J.), Atherosclerosis Research Unit, King Gustaf V Research Institute, Karolinska Institute, SE-171 77 Stockholm, Sweden; Minerva Foundation for Medical Research (E.K., H.Y.-J.), 00290 Helsinki, Finland; and Department of Mental Health and Alcohol Research (J.K.), National Public Health Institute, 00300 Helsinki, Finland

Address all correspondence and requests for reprints to: Kirsi Pietiläinen, M.D., Ph.D., M.Sc., Obesity Research Unit, Biomedicum Helsinki, C428a, P.O. Box 700, FIN-00029 HUS, Finland. E-mail: kirsi.pietilainen{at}helsinki.fi.


   Abstract
Top
 Abstract
Introduction
 Patients and Methods
 Results
 Discussion
 References
 
Context: Both acquired and genetic factors regulate adipose tissue function.

Objective: We determined whether adipose tissue mRNA expression is regulated by obesity, independently of genetic effects, by studying monozygotic (MZ) twins.

Design: Seventeen healthy pairs of MZ twins aged 24–27 yr (body mass index 20.0–33.9 kg/m2, intrapair differences in body weight 0.1–24.7 kg), were identified from the population-based FinnTwin16 cohort. Body fat percent was determined by dual-energy x-ray absorptiometry, sc and intraabdominal fat by magnetic resonance imaging, liver fat by proton spectroscopy, and insulin sensitivity by using the euglycemic insulin clamp technique. Adipocyte cell size and expression of 10 genes (real-time PCR) were determined in sc adipose tissue biopsies. Serum levels of some of the genes were measured using ELISA.

Results: Within MZ twin pairs, acquired obesity was significantly related to increased adipocyte size and increased adipose tissue mRNA expressions of leptin, TNF{alpha} and the macrophage marker CD68, and decreased mRNA expressions of adiponectin and peroxisome proliferator-activated receptor-{gamma}. Intrapair differences in liver fat correlated directly with those in leptin and CD68 expression. CD68 expression and serum TNF{alpha} concentrations were correlated with insulin resistance.

Conclusions: Acquired obesity independent of genetic influences is able to increase expression of macrophage and inflammatory markers and decrease adiponectin expression in adipose tissue.


   Introduction
Top
 Abstract
 Introduction
Patients and Methods
 Results
 Discussion
 References
 
OBESITY IS CLOSELY associated with several metabolic disturbances and with a low-grade inflammation, which may predispose obese individuals to atherosclerosis (1). Adipose tissue releases a number of proinflammatory molecules, several of which seem to predominantly originate from macrophages in the stromal vascular fraction of adipose tissue (2). These include TNF{alpha}, IL-6, and IL-8. Proinflammatory molecules have direct effects on adipose tissue metabolism, and their secretion is increased in obesity (2). TNF{alpha} from macrophages induces adipocyte apoptosis, impairs insulin signaling, and induces insulin resistance locally in adipocytes (3). Adipose tissue also expresses and secretes antiinflammatory and insulin-sensitizing molecules (2). Leptin is an adipocyte-derived peptide hormone with central and peripheral effects on energy balance (4). Its production and secretion from adipose tissue are positively correlated with increased adipocyte size and number (5). In contrast, obesity is negatively correlated with production of adiponectin, which decreases hepatic lipid accumulation (6). In adipocytes, adiponectin suppresses nuclear factor-{kappa}ß responses by repressing induction of IL-6 and TNF{alpha} expression and up-regulating peroxisome proliferator-activated receptor (PPAR)-{gamma} mRNA expression (7).

Although recent studies have shown increased macrophage accumulation and increased expression of proinflammatory molecules in adipose tissue (2) as well as decreased expression of insulin-sensitizing molecules (6), it is unknown whether these changes are genetically determined or an acquired consequence of obesity. Monozygotic (MZ) twin pairs discordant for obesity offer a unique opportunity to study effects of acquired obesity independently of confounding genetic influences. In the present study, we searched for such MZ twins to determine whether acquired obesity increases the adipose tissue expression of the macrophage marker CD68 and other genes thought to be involved in the development of insulin resistance. To this end, we measured expression of genes in adipose tissue and for some genes, their circulating levels in serum. Intrapair differences in gene expression were related to those in whole-body insulin sensitivity and liver fat content. Our results suggest that acquired obesity increases adipose tissue macrophage infiltration and that this phenomenon is related to development of insulin resistance.


   Patients and Methods
Top
 Abstract
 Introduction
 Patients and Methods
Results
 Discussion
 References
 
The study participants were recruited from the FinnTwin16 cohort (8, 9, 10, 11), a population-based, longitudinal study of five consecutive birth cohorts (1975–1979) of twins, their siblings, and their parents, identified through the national population registry of Finland. Twin pairs included in the current study were recruited based on their responses to questions on weight and height at age 23–27 yr. After screening all MZ twin pairs (n = 658), we identified 14 pairs with a reported body mass index (BMI) difference of at least 4 kg/m2, such that one co-twin was nonobese (BMI ~25 kg/m2), whereas the other was obese (BMI ~30 kg/m2). Nine of these pairs (five male and four female pairs) participated in the current study. In addition to these discordant pairs, we studied eight concordant MZ pairs with a reported BMI difference of less than 2 kg/m2 (two male and two female overweight pairs, two male and two female normal-weight pairs). The measured BMI differences ranged from 3.8 to 10.1 kg/m2 in the discordant and from 0.4 to 2.3 kg/m2 in the concordant pairs. Discordant pairs were the same age (25.4 ± 1.1 yr) as the concordant pairs (26.0 ± 1.0 yr). The subjects were healthy and normotensive and did not use concomitant medications except contraceptives. Their weight had been stable for at least 3 months before the study. Females were scheduled to attend during the follicular phase of their menstrual cycle. Monozygosity was confirmed by genotyping of 10 informative genetic markers (12). The subjects provided written informed consent. The protocol was designed and performed according to the principles of the Helsinki Declaration and was approved by the Ethical Committee of the Helsinki University Central Hospital.

Study design

All subjects were studied after an overnight fast starting at 0800 h. A blood sample was taken for measurement of serum insulin, adiponectin, leptin, TNF{alpha}, and IL-6 concentrations. A needle aspiration biopsy of sc abdominal fat at the level of the umbilicus was taken under local anesthesia (13). The fat sample was immediately frozen and stored in liquid nitrogen until analysis. Part of the biopsy was immediately treated with collagenase for isolation of fat cells for 30 min at 37 C. From this sample, the diameter of 200 adipocytes was determined using a light microscope. Total RNA and cDNA were prepared from frozen fat tissue (on average 100 mg). Whole-body insulin sensitivity was measured using the euglycemic hyperinsulinemic clamp technique (9). Body composition was measured by dual-energy x-ray absorptiometry (Lunar Prodigy, Madison, WI, software version 2.15) (14), sc and intraabdominal fat by magnetic resonance imaging of 16 transaxial scans reaching from 8 cm above to 8 cm below the fourth and fifth lumbar interspace (9) and liver fat content by proton spectroscopy (9, 15).

Total RNA and cDNA preparation

Frozen fat tissue (~100 mg) was homogenized in 2 ml of RNA STAT-60 (Tel-Test, Friendswood, TX) and total RNA isolated according to the manufacturer’s instructions. After DNase treatment (RNase-free DNase set; QIAGEN, Hilden, Germany), RNA was purified using the RNeasy minikit (QIAGEN). RNA concentrations were measured using the RiboGreen fluorescent nucleic acid stain (RNA quantification kit; Molecular Probes, Eugene, OR). The quality of RNA was checked by agarose gel electrophoresis. The yield of total RNA was 2.2 ± 0.9 µg per 100 mg adipose tissue wet weight. A total of 0.1 µg of RNA was transcribed into cDNA by use of Moloney murine leukemia virus reverse transcriptase (Life Technologies, Paisley, UK) and oligo(dT)12–18 primer.

Quantification of adiponectin, PPAR{gamma}, lipoprotein lipase (LPL), and ß-actin gene expression

Quantification of the mRNAs was performed by real-time PCR using LightCycler Technology (Roche Diagnostics GmbH, Mannheim, Germany). Two microliters of 1:10 diluted cDNA were brought to a final volume of 20 µl, which contained 3 mM MgCl2, 2 µl LightCycler-Fast Start DNA SYBR Green I mix (Roche Diagnostics), and 0.5 µM of primers. After initial activation of the DNA polymerase at 95 C for 10 min, the amplification conditions were as follows: 40 cycles consisting of denaturation at 95 C for 15 sec; annealing for 5 sec at 58 C (adiponectin), 56 C (PPAR{gamma}), 58 C (LPL), and 57 C (ß-actin); and extension at 72 C. The extension times (seconds) were calculated from the amplicon size (base pairs/25). Fluorescent data were acquired at the end of each extension phase. After amplification, a melting curve analysis from 65 to 95 C with a heating rate of 0.1 C/sec with a continuous fluorescence acquisition was made. Adiponectin, PPAR{gamma}, LPL, and ß-actin primers and the PCR protocol have been previously published (16, 17, 18). To account for differences in RNA loading, adiponectin, PPAR{gamma}, and LPL were expressed relative to ß-actin. The mRNA concentration of human ß-actin correlated with neither BMI (r = 0.23, P = 0.17) nor percent body fat (r = 0.09, P = 0.46). ß-Actin expression was similar in the leaner and heavier co-twins in the discordant (0.7 ± 0.3 and 0.9 ± 0.6, P = 0.21) and concordant pairs (1.1 ± 0.7 and 0.9 ± 0.3, P = 0.48).

Quantification of leptin, CD68, IL-6, TNF{alpha}, glucose transporter protein 4 (GLUT4), PPAR{delta}, PPAR-{gamma} coactivator 1 (PGC-1), and TATAbox-binding protein (TBP) gene expression

Quantification of the mRNAs was performed by Taqman real-time quantitative PCR using an ABI PRISM 7000 sequence detection system instrument and software (PE Applied Biosystems, Foster City, CA). CD68, IL-6, TNF{alpha}, and TBP were measured using predeveloped TaqMan assay reagents (PE Applied Biosystems). Primers and probes for leptin, GLUT4, PPAR{delta}, PGC-1, and the PCR protocol have been previously published (17, 18, 19). Differences in loading of RNA were adjusted for by expressing results relative to TBP. Expression levels were quantified (arbitrary units) by generating a six-point serial standard curve (20). TBP correlated with neither BMI (r = –0.18, P = 0.40) nor percent body fat (r = –0.23, P = 0.17). TBP expression was similar in the leaner and heavier co-twins in the discordant (4.1 ± 1.4·10–4 and 5.2 ± 2.7·10–4, P = 0.09) and concordant pairs (5.4 ± 1.9·10–4 and 5.7 ± 1.5·10–4, P = 0.89). Adiponectin, PPAR{gamma}, and LPL mRNA expressions were measured at the Helsinki University Central Hospital (Finland) and other genes at the Karolinska Institute (Stockholm, Sweden). This is why two different quantitative PCR methods, each with its own housekeeping gene, were used.

Serum adiponectin concentration and other measurements

Serum adiponectin concentration was measured using a commercial ELISA (human adiponectin ELISA kit, B-Bridge International, San Jose, CA). Serum leptin, TNF{alpha}, and IL-6 concentrations were measured using enzyme-linked immunoassays (Quantikine R&D Systems, Minneapolis, MN). Serum-free insulin concentration was determined with RIA (Phadeseph insulin RIA, Pharmacia & Upjohn Diagnostics, Uppsala, Sweden) after precipitation with polyethylene glycol (21).

Statistical analyses

Study of MZ twins is advantageous for examining relationships that are independent of genetic influences. Because MZ twins are genetically identical, any difference between the co-twins must be attributable to acquired factors (22). In this study, we tested the effects of acquired obesity on gene expression in adipose tissue. First, we compared, by paired Wilcoxon’s signed ranks test, whether the mRNA expression or other physical and biochemical characteristics differed between the leaner and heavier (as defined by BMI) co-twins in weight-discordant and -concordant pairs. Second, to assess whether the magnitude of intrapair differences in the physical and biochemical characteristics was related to differences in adipose tissue mRNA expression or serum adipokine concentrations, we calculated Spearman correlation coefficients between intrapair differences of selected variables. All pairs were included in these analyses. Male and female pairs were combined because by definition MZ co-twins are matched for gender (and age). Also, all intrapair differences in physical and biochemical characteristics were similar when comparing male and female pairs.

In individual twins, we assessed whether the expression of CD68, a macrophage-specific gene, was correlated with the expression of other genes supposed to be markers of stromal vascular or adipocyte compartments. For individual twins, the observations and their error terms may be correlated between co-twins. Therefore, when Pearson correlation coefficients and multiple regression ß-coefficients between specific genes were calculated, they were corrected for clustered sampling within twin pairs (23). All analyses were conducted with the Stata software (release 8.0; Stata Corp., College Station, TX). Data are shown as mean ± SD unless indicated otherwise. Median (minimum-maximum) were shown for skewed data, i.e. liver fat, serum TNF{alpha}, and serum IL-6. P < 0.05 was considered statistically significant.


   Results
Top
 Abstract
 Introduction
 Patients and Methods
 Results
Discussion
 References
 
Comparisons between the leaner and heavier co-twins

Physical and biochemical characteristics of the twins are shown in Table 1Go. In the discordant MZ twin pairs, the heavier co-twins had more sc, intraabdominal fat, and liver fat and larger adipocytes than the leaner co-twins, whereas there was no difference in these measures in the weight-concordant pairs.


View this table:
[in this window]
[in a new window]
  		TABLE 1. Physical and biochemical characteristics of the 17 MZ twin pairs

 
The heavier co-twins of the discordant pairs had lower whole-body insulin sensitivity (M-value) and higher fasting serum insulin concentrations than the leaner co-twins. Fasting serum adiponectin concentrations were lower and serum leptin and IL-6 concentrations higher in the heavier co-twins. None of these variables differed between the concordant co-twins (Table 1Go).

Compared with the leaner co-twins, the heavier co-twins of the discordant pairs had higher adipose tissue mRNA expressions of leptin, CD68, and TNF{alpha} and lower expressions of adiponectin and PPAR{gamma} (Fig. 1Go). Expressions of LPL, IL-6, PPAR{delta}, PGC-1, and GLUT4 were similar (data not shown). Adipose tissue mRNA expression patterns were similar between the concordant co-twins (Fig. 1Go).


Figure 1
View larger version (23K):
[in this window]
[in a new window]
  		FIG. 1. Subcutaneous abdominal adipose tissue expression of adiponectin, PPAR{gamma}, leptin, CD68, and TNF{alpha} in the leaner and heavier MZ co-twins of nine pairs discordant for obesity (intrapair differences in BMI 3.8–10.1 kg/m2) (black bars) and eight weight-concordant pairs (intrapair differences in BMI 0.4–2.3 kg/m2) (white bars). The results are shown in arbitrary units after normalizing for housekeeping gene expression. Data are shown as mean ± SE. *, P ≤ 0.05, paired Wilcoxon’s signed ranks test.

 
Intrapair differences in obesity, adipose tissue mRNA expression, and insulin sensitivity

The intrapair difference in abdominal sc fat mass was directly related to that in leptin (r = 0.66, P = 0.004), CD68 (r = 0.70, P = 0.002), and TNF{alpha} (r = 0.48, P = 0.049) and inversely to adiponectin expression (r = –0.48, P = 0.049). Intrapair differences in liver fat correlated with those in leptin (r = 0.60, P = 0.011) and CD68 expression (r = 0.63, P = 0.009; Fig. 2Go), whereas no genes were significantly related to differences in intraabdominal fat (e.g. leptin r = 0.43, P = 0.082 and CD68 r = 0.34, P = 0.20). Increased adipocyte cell size, a direct correlate of sc fat mass (r = 0.85, P < 0.0001), was related to increased CD68 (r = 0.64, P = 0.008; Fig. 2Go) and TNF{alpha} expression (r = 0.60, P = 0.011) within pairs.


Figure 2
View larger version (12K):
[in this window]
[in a new window]
  		FIG. 2. The relationships (Spearman correlation) between intrapair differences ({Delta}) in sc abdominal adipose tissue expression of CD68 and {Delta}adipocyte size (A), {Delta}liver fat (B), and {Delta}M-value (C) in 17 MZ twin pairs ({Delta}BMI 0.4–10.1 kg/m2).

 
The intrapair differences in sc and intraabdominal fat mass correlated with those in the M-value (r = –0.60, P = 0.011 and r = –0.55, P = 0.02, respectively) as well as with those in serum insulin concentrations (r = 0.59, P = 0.012 and r = 0.69, P = 0.002, respectively). Liver fat correlated with serum insulin only (r = 0.49, P = 0.048). Increased expression of CD68 was associated with a low M-value (r = –0.60, P = 0.013; Fig. 2Go) and high serum insulin concentration (r = 0.51, P = 0.044) within pairs. High insulin resistance as judged by serum insulin was also related to lower expression of PPAR{gamma} (r = –0.49, P = 0.046).

Intrapair differences in obesity, adipokine serum concentrations, and insulin sensitivity

Of serum adipokines, leptin was most significantly correlated with intrapair differences in sc (r = 0.86, P = 0.0001) and intraabdominal fat (r = 0.56, P = 0.020). Intrapair differences in liver fat did not correlate with adipokines in serum (r = –0.22, r = 0.18, r = 0.31, and r = 0.08 for adiponectin, TNF{alpha}, leptin, and IL-6, respectively). Differences in adipocyte cell size were significantly related to those in serum leptin (r = 0.71, P = 0.001) and serum IL-6 concentrations (r = 0.57, P = 0.017). High insulin concentrations were related to low serum adiponectin (r = –0.52, P = 0.033) and high serum TNF{alpha} concentrations (r = 0.56, P = 0.020) within pairs. Intrapair differences in M-value and serum adipokines did not correlate significantly (data not shown).

Relationships between adipose tissue mRNA expressions

In individual twins, we analyzed whether the expression of CD68, a macrophage-specific marker, was related to the expression of other genes. CD68 expression correlated positively with expressions of TNF{alpha} (r = 0.52, P = 0.001) and leptin (r = 0.41, P = 0.017) and inversely with adiponectin (r = –0.52, P = 0.001), PPAR{gamma} (r = –0.42, P = 0.008), and LPL (r = –0.35, P = 0.024). In stepwise multiple regression analysis including all the above genes, expressions of TNF{alpha} (beta = 0.4 ± 0.2, P = 0.048) and adiponectin (beta = –0.4 ± 0.2, P = 0.043) remained significantly correlated with CD68 expression, with an R2 of 38%, P = 0.0006.


   Discussion
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Discussion
References
 
In the present study, we studied a rare sample of young adult MZ twins discordant for obesity and showed that in the obese co-twins, adipose tissue mRNA expression profile differed from that in the nonobese co-twins. Adiponectin and PPAR{gamma} mRNA expressions were significantly lower, whereas leptin, CD68, and TNF{alpha} expressions were significantly higher in the obese than the nonobese co-twins. The magnitude of intrapair differences in whole-body and sc fat was directly related to differences in leptin, CD68, and TNF{alpha} and inversely to differences in adiponectin expression. Intrapair differences in liver fat were directly related to leptin and CD68 and intrapair differences in adipocyte cell size to CD68 and TNF{alpha} expressions. These data suggest that acquired obesity independent of genetic influences is able to increase expression of macrophage and inflammatory markers and decrease adiponectin expression in adipose tissue.

Adipocyte differentiation may be impaired in obesity, leading to hypertrophy and increased insulin resistance (24). We found that in analyses controlling for genetic influences within pairs, adipocyte size was positively correlated with measures of body fat and negatively with insulin sensitivity. We also found PPAR{gamma} mRNA expression in sc adipose tissue to be decreased in the obese co-twins. Because PPAR{gamma} is needed for adipocyte differentiation, low PPAR{gamma} is consistent with impaired adipocyte differentiation (25). PPAR{gamma} is expressed as two isoforms, PPAR{gamma}1 and PPAR{gamma}2, which differ by 30 amino acids at the NH2 terminus. A limitation in the present study was that we measured PPAR{gamma} rather than PPAR{gamma}1 and PPAR{gamma}2 expressions separately. However, PPAR{gamma}2 expression is more than 20-fold higher than that of PPAR{gamma}1 in adipose tissue (26). The lower PPAR{gamma} expression observed in the present study in the obese co-twins was therefore likely to reflect PPAR{gamma}2 mRNA expression. Consistent with previous findings (27), both adipocyte size and body fat were positively correlated with plasma leptin levels in the current study. The present study extends these findings by demonstrating that these relationships are independent of genetic influences.

The number of macrophages and expression of macrophage markers are increased in obesity (2) and can be reduced by weight loss (28). Weisberg et al. (29) found in immunohistochemical studies in mice that the percentage of cells in different adipose tissue depots expressing the macrophage marker F4/80 (F4/80+) was significantly and positively correlated with both adipocyte size and body mass. Similar relationships were found in human sc adipose tissue stained for the macrophage surface marker CD68 (29). In this study we used CD68 as a macrophage marker. CD68 mRNA expression in isolated adipocytes has been found to be only 2% (30) or less than 10% (31) of that in stromal vascular cells, indicating that CD68 is mainly expressed by macrophages and not by adipocytes. Our results confirm previous data showing that obese human adipose tissue overexpresses CD68 and extend them by showing that this alteration can be caused by acquired obesity.

The signal triggering macrophage infiltration into adipose tissue in obesity is still unclear. One explanation could be increased expression and secretion of chemoattractants including the monocyte chemoattractant protein-1 from hypertrophic adipocytes. The expression of monocyte chemoattractant protein-1 in isolated human adipocytes is substantially increased in obesity (30) and by TNF{alpha} (32). We found intrapair differences in CD68 mRNA expression, together with TNF{alpha} expression and plasma IL-6, to correlate positively with differences in adipocyte cell size. In the study by Weisberg et al. (29), adipose tissue macrophages were responsible for almost all adipose tissue TNF{alpha} expression. In the present study, TNF{alpha} expression was positively and that of adiponectin negatively associated with CD68 expression. These data are consistent with the idea that TNF{alpha} from macrophages acts as a paracrine signal locally in adipose tissue to down-regulate adiponectin expression (33). Serum TNF{alpha} concentration was not increased by obesity in the present study, consistent with catheterization studies in humans showing no release of TNF{alpha} from adipose tissue into the systemic circulation (34).

Liver fat content is positively correlated with fasting insulin concentrations (35) and inversely with direct measures of hepatic insulin sensitivity (36) and with serum adiponectin concentrations (35, 37). The close correlation between adipose tissue CD68 expression and liver fat in the current study supports this notion but does not exclude other possibilities. For example, macrophages in the liver (i.e. Kupfer cells) could also, via production of TNF{alpha}, contribute to insulin resistance and fat accumulation in this organ (38). In addition, liver fat may be regulated by other adiponectin-independent factors such as dietary fat content (39).

In conclusion, acquired obesity, in otherwise apparently healthy, young individuals, is characterized by increased expression of the macrophage marker CD68 in sc adipose tissue. CD68 expression parallels low adiponectin expression and correlates positively with insulin resistance and liver fat content. These data on MZ twins imply that acquired obesity contributes to the development of insulin resistance and its consequences.


   Acknowledgments
 
The authors thank Erjastiina Heikkinen, Katja Tuominen, Mia Urjansson, and Pentti Pölönen for their expertise and all volunteers.


   Footnotes
 
This work was supported by the National Institute of Alcohol Abuse and Alcoholism (AA08315 and AA12502), Academy of Finland (44069 and 201461), European Union Fifth Framework Program (QLRT-1999-00916, QLG2-CT-2002-01254), Helsinki University Central Hospital grants, the Swedish Heart-Lung Foundation, the Swedish Medical Research Council (8691 and 12659), the Swedish Diabetes Foundation, Liv och Hälsa, the Karolinska Institute, the Stockholm County Council, and Biovitrum. K.H.P. was supported by the following foundations: Yrjö Jahnsson, Jalmari & Rauha Ahokas, Juho Vainio, Finnish Cultural, Finnish Medical Foundation, and Research Foundation of the Orion Corp. E.K. was supported by the Center for International Mobility and Minerva Foundation.

First Published Online April 11, 2006

1 K.H.P. and K.K. contributed equally to this work. Back

Abbreviations: BMI, Body mass index; GLUT4, glucose transporter protein 4; LPL, lipoprotein lipase; MZ, monozygotic; PGC, PPAR-{gamma} coactivator; PPAR, peroxisome proliferator-activated receptor; TBP, TATAbox-binding protein.

Received December 30, 2005.

Accepted April 4, 2006.


   References
Top
 Abstract
 Introduction
 Patients and Methods
 Results
 Discussion
 References
 

  1. Lyon CJ, Law RE, Hsueh WA 2003 Minireview: adiposity, inflammation, and atherogenesis. Endocrinology 144:2195–2200[Abstract/Free Full Text]
  2. Bouloumie A, Curat CA, Sengenes C, Lolmede K, Miranville A, Busse R 2005 Role of macrophage tissue infiltration in metabolic diseases. Curr Opin Clin Nutr Metab Care 8:347–354[Medline]
  3. Sethi JK, Hotamisligil GS 1999 The role of TNF{alpha} in adipocyte metabolism. Semin Cell Dev Biol 10:19–29[CrossRef][Medline]
  4. Hukshorn CJ, Saris WH 2004 Leptin and energy expenditure. Curr Opin Clin Nutr Metab Care 7:629–633[CrossRef][Medline]
  5. Couillard C, Mauriege P, Imbeault P, Prud’homme D, Nadeau A, Tremblay A, Bouchard C, Despres JP 2000 Hyperleptinemia is more closely associated with adipose cell hypertrophy than with adipose tissue hyperplasia. Int J Obes Relat Metab Disord 24:782–788[CrossRef][Medline]
  6. Yamauchi T, Kamon J, Waki H, Terauchi Y, Kubota N, Hara K, Mori Y, Ide T, Murakami K, Tsuboyama-Kasaoka N, Ezaki O, Akanuma Y, Gavrilova O, Vinson C, Reitman ML, Kagechika H, Shudo K, Yoda M, Nakano Y, Tobe K, Nagai R, Kimura S, Tomita M, Froguel P, Kadowaki T 2001 The fat-derived hormone adiponectin reverses insulin resistance associated with both lipoatrophy and obesity. Nat Med 7:941–946[CrossRef][Medline]
  7. Ajuwon KM, Spurlock ME 2005 Adiponectin inhibits LPS-induced NF-{kappa}B activation and IL-6 production and increases PPAR{gamma}2 expression in adipocytes. Am J Physiol Regul Integr Comp Physiol 288:R1220–R1225
  8. Kaprio J, Pulkkinen L, Rose RJ 2002 Genetic and environmental factors in health-related behaviors: studies on Finnish twins and twin families. Twin Res 5:366–371[CrossRef][Medline]
  9. Pietiläinen KH, Rissanen A, Kaprio J, Mäkimattila S, Häkkinen AM, Westerbacka J, Sutinen J, Vehkavaara S, Yki-Järvinen H 2005 Acquired obesity is associated with increased liver fat, intra-abdominal fat, and insulin resistance in young adult monozygotic twins. Am J Physiol Endocrinol Metab 288:E768–E774
  10. Gertow K, Pietiläinen KH, Yki-Järvinen H, Kaprio J, Rissanen A, Eriksson P, Hamsten A, Fisher RM 2004 Expression of fatty-acid-handling proteins in human adipose tissue in relation to obesity and insulin resistance. Diabetologia 47:1118–1125[Medline]
  11. Kannisto K, Pietiläinen KH, Ehrenborg E, Rissanen A, Kaprio J, Hamsten A, Yki-Järvinen H 2004 Overexpression of 11ß-hydroxysteroid dehydrogenase-1 in adipose tissue is associated with acquired obesity and features of insulin resistance: studies in young adult monozygotic twins. J Clin Endocrinol Metab 89:4414–4421[Abstract/Free Full Text]
  12. Pietiläinen KH, Rissanen A, Laamanen M, Lindholm AK, Markkula H, Yki-Järvinen H, Kaprio J 2004 Growth patterns in young adult monozygotic twin pairs discordant and concordant for obesity. Twin Res 7:421–429[CrossRef][Medline]
  13. Yki-Järvinen H, Nikkilä EA, Kubo K, Foley JE 1986 Assay of glucose transport in human fat cells obtained by needle biopsy. Diabetologia 29:287–290[CrossRef][Medline]
  14. Mazess RB, Barden HS, Bisek JP, Hanson J 1990 Dual-energy x-ray absorptiometry for total-body and regional bone-mineral and soft-tissue composition. Am J Clin Nutr 51:1106–1112[Abstract/Free Full Text]
  15. Ryysy L, Häkkinen AM, Goto T, Vehkavaara S, Westerbacka J, Halavaara J, Yki-Järvinen H 2000 Hepatic fat content and insulin action on free fatty acids and glucose metabolism rather than insulin absorption are associated with insulin requirements during insulin therapy in type 2 diabetic patients. Diabetes 49:749–758[Abstract]
  16. Sutinen J, Korsheninnikova E, Funahashi T, Matsuzawa Y, Nyman T, Yki-Järvinen H 2003 Circulating concentration of adiponectin and its expression in subcutaneous adipose tissue in patients with highly active antiretroviral therapy-associated lipodystrophy. J Clin Endocrinol Metab 88:1907–1910[Abstract]
  17. Kannisto K, Sutinen J, Korsheninnikova E, Fisher RM, Ehrenborg E, Gertow K, Virkamäki A, Nyman T, Vidal H, Hamsten A, Yki-Järvinen H 2003 Expression of adipogenic transcription factors, peroxisome proliferator-activated receptor {gamma} coactivator 1, IL-6 and CD45 in subcutaneous adipose tissue in lipodystrophy associated with highly active antiretroviral therapy. AIDS 17:1753–1762[CrossRef][Medline]
  18. Sutinen J, Kannisto K, Korsheninnikova E, Fisher RM, Ehrenborg E, Nyman T, Virkamäki A, Funahashi T, Matsuzawa Y, Vidal H, Hamsten A, Yki-Järvinen H 2004 Effects of rosiglitazone on gene expression in subcutaneous adipose tissue in highly active antiretroviral therapy-associated lipodystrophy. Am J Physiol Endocrinol Metab 286:E941–E949
  19. Yki-Järvinen H, Sutinen J, Silveira A, Korsheninnikova E, Fisher RM, Kannisto K, Ehrenborg E, Eriksson P, Hamsten A 2003 Regulation of plasma PAI-1 concentrations in HAART-associated lipodystrophy during rosiglitazone therapy. Arterioscler Thromb Vasc Biol 23:688–694[Abstract/Free Full Text]
  20. Way JM, Harrington WW, Brown KK, Gottschalk WK, Sundseth SS, Mansfield TA, Ramachandran RK, Willson TM, Kliewer SA 2001 Comprehensive messenger ribonucleic acid profiling reveals that peroxisome proliferator-activated receptor {gamma} activation has coordinate effects on gene expression in multiple insulin-sensitive tissues. Endocrinology 142:1269–1277[Abstract/Free Full Text]
  21. Desbuquois B, Aurbach GD 1971 Use of polyethylene glycol to separate free and antibody-bound peptide hormones in radioimmunoassays. J Clin Endocrinol Metab 33:732–738[Abstract/Free Full Text]
  22. Martin N, Boomsma D, Machin G 1997 A twin-pronged attack on complex traits. Nat Genet 17:387–392[CrossRef][Medline]
  23. Williams RL 2000 A note on robust variance estimation for cluster-correlated data. Biometrics 56:645–646[CrossRef][Medline]
  24. Yang X, Jansson PA, Nagaev I, Jack MM, Carvalho E, Sunnerhagen KS, Cam MC, Cushman SW, Smith U 2004 Evidence of impaired adipogenesis in insulin resistance. Biochem Biophys Res Commun 317:1045–1051[CrossRef][Medline]
  25. De Souza CJ, Eckhardt M, Gagen K, Dong M, Chen W, Laurent D, Burkey BF 2001 Effects of pioglitazone on adipose tissue remodeling within the setting of obesity and insulin resistance. Diabetes 50:1863–1871[Abstract/Free Full Text]
  26. Giusti V, Verdumo C, Suter M, Gaillard RC, Burckhardt P, Pralong F 2003 Expression of peroxisome proliferator-activated receptor-{gamma}1 and peroxisome proliferator-activated receptor-{gamma}2 in visceral and subcutaneous adipose tissue of obese women. Diabetes 52:1673–1676[Abstract/Free Full Text]
  27. Ribiere C, Plut C 2005 Nutritional regulation of leptin signaling. Curr Hypertens Rep 7:11–16[CrossRef][Medline]
  28. Clement K, Viguerie N, Poitou C, Carette C, Pelloux V, Curat CA, Sicard A, Rome S, Benis A, Zucker JD, Vidal H, Laville M, Barsh GS, Basdevant A, Stich V, Cancello R, Langin D 2004 Weight loss regulates inflammation-related genes in white adipose tissue of obese subjects. FASEB J 18:1657–1669[Abstract/Free Full Text]
  29. Weisberg SP, McCann D, Desai M, Rosenbaum M, Leibel RL, Ferrante Jr AW 2003 Obesity is associated with macrophage accumulation in adipose tissue. J Clin Invest 112:1796–1808[CrossRef][Medline]
  30. Christiansen T, Richelsen B, Bruun JM 2005 Monocyte chemoattractant protein-1 is produced in isolated adipocytes, associated with adiposity and reduced after weight loss in morbid obese subjects. Int J Obes Relat Metab Disord 29:146–150[CrossRef][Medline]
  31. Di Gregorio GB, Yao-Borengasser A, Rasouli N, Varma V, Lu T, Miles LM, Ranganathan G, Peterson CA, McGehee RE, Kern PA 2005 Expression of CD68 and macrophage chemoattractant protein-1 genes in human adipose and muscle tissues: association with cytokine expression, insulin resistance, and reduction by pioglitazone. Diabetes 54:2305–2313[Abstract/Free Full Text]
  32. Wang B, Jenkins JR, Trayhurn P 2005 Expression and secretion of inflammation-related adipokines by human adipocytes differentiated in culture: integrated response to TNF{alpha}. Am J Physiol Endocrinol Metab 288:E731–E740
  33. Bruun JM, Lihn AS, Verdich C, Pedersen SB, Toubro S, Astrup A, Richelsen B 2003 Regulation of adiponectin by adipose tissue-derived cytokines: in vivo and in vitro investigations in humans. Am J Physiol Endocrinol Metab 285:E527–E533
  34. Mohamed-Ali V, Goodrick S, Rawesh A, Katz DR, Miles JM, Yudkin JS, Klein S, Coppack SW 1997 Subcutaneous adipose tissue releases interleukin-6, but not tumor necrosis factor-{alpha}, in vivo. J Clin Endocrinol Metab 82:4196–4200[Abstract/Free Full Text]
  35. Westerbacka J, Corner A, Tiikkainen M, Tamminen M, Vehkavaara S, Häkkinen AM, Fredriksson J, Yki-Järvinen H 2004 Women and men have similar amounts of liver and intra-abdominal fat, despite more subcutaneous fat in women: implications for sex differences in markers of cardiovascular risk. Diabetologia 47:1360–1369[Medline]
  36. Yki-Järvinen H, Westerbacka J 2005 The fatty liver and insulin resistance. Curr Mol Med 5:287–295[CrossRef][Medline]
  37. Bugianesi E, Pagotto U, Manini R, Vanni E, Gastaldelli A, De Iasio R, Gentilcore E, Natale S, Cassader M, Rizzetto M, Pasquali R, Marchesini G 2005 Plasma adiponectin in nonalcoholic fatty liver is related to hepatic insulin resistance and hepatic fat content, not to liver disease severity. J Clin Endocrinol Metab 90:3498–3504[Abstract/Free Full Text]
  38. Cai D, Yuan M, Frantz DF, Melendez PA, Hansen L, Lee J, Shoelson SE 2005 Local and systemic insulin resistance resulting from hepatic activation of IKK-ß and NF-{kappa}B. Nat Med 11:183–190[CrossRef][Medline]
  39. Westerbacka J, Lammi K, Häkkinen AM, Rissanen A, Salminen I, Aro A, Yki-Järvinen H 2005 Dietary fat content modifies liver fat in overweight nondiabetic subjects. J Clin Endocrinol Metab 90:2804–2809[Abstract/Free Full Text]



This article has been cited by other articles:


Home page
 J EndocrinolHome page
I. J Bujalska, O. M Durrani, J. Abbott, C. U Onyimba, P. Khosla, A. H Moosavi, T. T Q Reuser, P. M Stewart, J. W Tomlinson, E. A Walker, et al.
Characterisation of 11{beta}-hydroxysteroid dehydrogenase 1 in human orbital adipose tissue: a comparison with subcutaneous and omental fat
J. Endocrinol., February 1, 2007; 192(2): 279 - 288.
[Abstract] [Full Text] [PDF]

Home page
 J. Clin. Endocrinol. Metab.Home page
S. Pilz, H. Mangge, B. Wellnitz, U. Seelhorst, B. R. Winkelmann, B. Tiran, B. O. Boehm, and W. Marz
Adiponectin and Mortality in Patients Undergoing Coronary Angiography
J. Clin. Endocrinol. Metab., November 1, 2006; 91(11): 4277 - 4286.
[Abstract] [Full Text] [PDF]

This Article
Right arrow Abstract Freely available
Right arrow Full Text (PDF)
Right arrow Submit a related Letter to the Editor
Right arrow Alert me when this article is cited
Right arrow Alert me when eLetters are posted
Right arrow Alert me if a correction is posted
Right arrow Citation Map
Services
Right arrow Email this article to a friend
Right arrow Similar articles in this journal
Right arrow Similar articles in PubMed
Right arrow Alert me to new issues of the journal
Right arrow Download to citation manager
Right arrow Request Copyright Permission
Citing Articles
Right arrow Citing Articles via HighWire
Right arrow Citing Articles via Google Scholar
Google Scholar
Right arrow Articles by Pietiläinen, K. H.
Right arrow Articles by Yki-Järvinen, H.
Right arrow Search for Related Content
PubMed
Right arrow PubMed Citation
Right arrow Articles by Pietiläinen, K. H.
Right arrow Articles by Yki-Järvinen, H.
Related Collections
Right arrow Metabolism
Right arrow Obesity

HOME HELP FEEDBACK SUBSCRIPTIONS ARCHIVE SEARCH TABLE OF CONTENTS
Endocrinology Endocrine Reviews J. Clin. End. & Metab.
Molecular Endocrinology Recent Prog. Horm. Res. All Endocrine Journals