RESUMO
We have investigated the difference in gene expression of six proteins secreted by adipocytes in paired biopsies from visceral and abdominal subcutaneous adipose tissue in nine individuals with various degrees of obesity. The mRNAs levels of leptin, TNFalpha, angiotensinogen, acylation stimulating protein (ASP), cholesterol ester transfer protein (CETP) and phospholipid transfer protein (PLTP) were quantified by RT-competitive PCR. ASP and angiotensinogen mRNA levels were higher in the visceral fat, whereas the mRNA levels of leptin and CETP were higher in the subcutaneous depot. TNFalpha mRNA expression was similar in the two sites. For angiotensinogen, the difference was more pronounced in the subjects with body mass index (BMI) lower than 30 kg/m(2) whereas for ASP, CETP and leptin, the difference was observed regardless the BMI of the subjects. PLTP mRNA levels in subcutaneous, but not in the visceral, adipose tissue were positively related to the BMI of the subjects. These results strongly suggest that visceral and subcutaneous adipocytes may have different properties in the production of bioactive molecules.
Assuntos
Adipócitos/metabolismo , Complemento C3a/análogos & derivados , Derme , Glicoproteínas , Omento , Proteínas de Transferência de Fosfolipídeos , Proteínas/genética , RNA Mensageiro/biossíntese , Adulto , Idoso , Angiotensinogênio/biossíntese , Angiotensinogênio/genética , Proteínas Sanguíneas/biossíntese , Proteínas Sanguíneas/genética , Índice de Massa Corporal , Proteínas de Transporte/biossíntese , Proteínas de Transporte/genética , Proteínas de Transferência de Ésteres de Colesterol , Feminino , Humanos , Leptina/biossíntese , Leptina/genética , Masculino , Proteínas de Membrana/biossíntese , Proteínas de Membrana/genética , Pessoa de Meia-Idade , Biossíntese de Proteínas , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Fator de Necrose Tumoral alfa/biossíntese , Fator de Necrose Tumoral alfa/genéticaRESUMO
One of the key features of atherosclerosis formation and progression is 'dedifferentiation' of contractile arterial smooth muscle cells (SMC) in synthetic cells. In primary cultures and subcultures before 10 and after 200 passages, SMC exhibit contractile-like, synthetic and transformed phenotypes, respectively, providing a good model for studying dedifferentiation process in vitro: the rationale for comparing these phenotypes of SMC in vivo rests in similar changes in cytoenzymatic and cytoskeletal features. In vivo, dedifferentiated SMC are transformed into foam cells by accumulating lipids. Thus, the aim of this study was to determine whether cholesterol metabolism undergoes changes in dedifferentiated cells and the three cultured phenotypes were compared in regard to their cholesterol efflux mechanisms. Phenotypic changes were shown to be associated with decrease in intracellular cholesterol apoprotein mediated efflux and translocation but also with decrease in high affinity binding sites for native HDL. Thus, the dedifferentiation process triggers a need for increased supply of cholesterol for membrane synthesis and efflux down-regulation mechanisms are aimed at maximizing cholesterol availability to the cell. Plasma membrane cholesterol efflux, which seems to be apoprotein-independent, decrease slightly with cell dedifferentiation suggesting either modifications in the dedifferentiated cell membranes physical properties. Taken together, these different results showed that dedifferentiation of arterial SMC is associated with decrease in the different steps of the efflux process, which could constitute one of the early events in their foam cell transformation.
Assuntos
Colesterol/metabolismo , Lipoproteínas HDL/metabolismo , Músculo Liso Vascular/metabolismo , Animais , Aorta , Arteriosclerose/metabolismo , Sítios de Ligação , Membrana Celular/metabolismo , Membranas Intracelulares/metabolismo , Lipoproteínas HDL/isolamento & purificação , Lipoproteínas LDL/isolamento & purificação , Lipoproteínas LDL/metabolismo , Fenótipo , Ratos , TrítioRESUMO
We studied the effect of an oral fat load on plasma acylation stimulating protein (ASP) concentrations in 9 lean healthy (age 59+/-2 years, body mass index [BMI] 23.2+/-0.4 kg/m(2); both mean+/-SEM), 9 obese nondiabetic (58+/-2 years, BMI 29.4+/-0.5 kg/m(2)), and 12 type 2 diabetic (60+/-2 years, BMI 29.6+/-1.0 kg/m(2)) men. Because ASP is a cleavage product of complement protein C3 (C3adesArg) and its secretion is regulated by insulin, we also examined the subcutaneous adipose tissue expression of C3 mRNA before and after a 240-minute euglycemic hyperinsulinemic clamp in a subgroup of these men. Plasma ASP concentration and adipose tissue C3 mRNA expression were higher in the obese groups than in the lean men. Plasma ASP concentration did not change significantly after the fat load. Fasting plasma ASP concentration and C3 mRNA expression were correlated negatively with insulin sensitivity and positively with the magnitude of postprandial lipemia in nondiabetic but not in type 2 diabetic men. The expression of C3 mRNA was not regulated by insulin. These data suggest that ASP is associated with whole-body glucose and lipid metabolism in nondiabetic individuals, whereas metabolic disturbances in diabetes may overcome the regulatory role of ASP in lipid and glucose metabolism.
Assuntos
Tecido Adiposo/metabolismo , Proteínas Sanguíneas/metabolismo , Complemento C3/genética , Complemento C3a/análogos & derivados , Diabetes Mellitus Tipo 2/metabolismo , Complemento C3/biossíntese , Diabetes Mellitus/genética , Diabetes Mellitus/metabolismo , Diabetes Mellitus Tipo 2/genética , Jejum , Gorduras/administração & dosagem , Humanos , Hiperlipidemias/etiologia , Hiperlipidemias/metabolismo , Resistência à Insulina , Masculino , Pessoa de Meia-Idade , Obesidade , Período Pós-Prandial , RNA Mensageiro/biossíntese , Triglicerídeos/sangueRESUMO
To determine the effect of hyperthyroidism on hepatic lipogenesis and cholesterol synthesis we measured these metabolic pathways (deuterated water method) in euthyroid and hyperthyroid subjects investigated in the postabsorptive state. Hyperthyroid patients had increased concentrations of glucose (P < 0.05), insulin (P < 0.05), nonesterified fatty acids (P < 0.01), and triglycerides (P < 0.05) and decreased levels of plasma cholesterol (P < 0.01). The contribution of hepatic lipogenesis to plasma triglycerides was largely increased in hyperthyroid subjects (23.0 +/- 1.8% vs. 7.5 +/- 0.2%; P < 0.001), whereas the fractional synthetic rate of cholesterol was moderately higher (5.0 +/- 0.8% vs. 3.3 +/- 0.2%; P < 0.05). mRNA levels of beta-hydroxy-beta-methyl glutaryl-coenzyme A reductase, measured in circulating mononuclear cells, were increased (P < 0.05), whereas those of low density lipoprotein (LDL) receptor and LDL receptor-related protein were unchanged. Sterol responsive element binding protein-1c mRNAs were undetectable in mononuclear cells from both groups of subjects. The large stimulation of hepatic lipogenesis in hyperthyroid patients is probably explained by both a direct action of thyroid hormones and the increase in insulin. It could contribute to their moderate rise in triglycerides levels. The decreased plasma cholesterol level is observed despite an enhanced synthetic rate and is thus related to an increased clearance rate. The lack of increased expression of LDL receptor and LDL receptor-related protein suggests that other receptors are implicated.
Assuntos
Colesterol/biossíntese , Hipertireoidismo/metabolismo , Lipídeos/biossíntese , Fígado/metabolismo , Fatores de Transcrição , Adulto , Proteínas Estimuladoras de Ligação a CCAAT/biossíntese , Proteínas de Ligação a DNA/biossíntese , Feminino , Doença de Graves/metabolismo , Hepatócitos/enzimologia , Hepatócitos/metabolismo , Humanos , Hidroximetilglutaril-CoA Redutases/biossíntese , Hidroximetilglutaril-CoA Redutases/metabolismo , Masculino , Monócitos/efeitos dos fármacos , Monócitos/metabolismo , RNA Mensageiro/biossíntese , Receptores de LDL/biossíntese , Receptores de LDL/metabolismo , Reação em Cadeia da Polimerase Via Transcriptase Reversa , Proteína de Ligação a Elemento Regulador de Esterol 1RESUMO
During the atherogenic process in vivo, arterial smooth muscle cells (SMC) undergo changes in their phenotype. In the present study, rat SMC from primary cultures and from subcultures before 10 and after 200 passages, showing contractile-like, synthetic and transformed phenotypes, respectively, were compared in regard to their lipid content and biosynthesis. The rationale for comparing these phenotypes rests in the similar changes in phenotype of SMC that occur in the formation and progression of atherosclerotic lesions. Phenotype changes were shown to be associated with changes in the phospholipid content of SMC. Phospholipid levels increased, but not as significantly as did cholesterol levels when passing from contractile to synthetic and transformed cells (1.23 +/- 0.18, 2.28 +/- 0.26 and 3.25 +/- 0.23 micrograms/10(6) cells, respectively). Cholesterol normalized in respect to cell protein was increased to the same extent. Lipid synthesis as judged by [14C]acetate incorporation was increased 3- to 12-fold in the synthetic and transformed cells, respectively, compared to contractile cells. After thin-layer chromatography, radioactivity was shown to be markedly increased in most of the lipid fractions, but label in the cholesterol fraction of synthetic and transformed cells was increased by 7- and 21-fold, respectively. Thus, SMC in vitro were shown to drastically increase cholesterol biosynthesis associated with phenotype changes. Such changes are known to occur in vivo and might represent a critical step in the deposition of excess cholesterol within foam cells.
Assuntos
Lipídeos/biossíntese , Músculo Liso Vascular/metabolismo , Animais , Aorta Torácica/citologia , Aorta Torácica/metabolismo , Células Cultivadas , Colesterol/metabolismo , Músculo Liso Vascular/citologia , Fenótipo , Fosfolipídeos/metabolismo , RatosRESUMO
The aim of our work was to determine whether fatty acid modifications in smooth muscle cell phospholipids affect cholesterol efflux and desorption. [3H]Cholesterol was used to label cholesterol pools in the whole cell or selectively in the plasma membrane. Cells were incubated for 12 h in order to increase oleate, linoleate, arachidonate, eicosapentaenoic acid (EPA) or docosahexaenoic acid (DHA) in phospholipids. Cholesterol efflux was monitored using native or tetranitromethane modified high-density lipoprotein3 (HDL3). When all cholesterol pools were labeled, the efflux from cells treated with different fatty acids were not different. Plasma membrane cholesterol efflux remained unchanged after oleate, linoleate or arachidonate treatments, but was markedly increased after EPA and DHA enrichment, both with native HDL3 and with tetranitromethane-high-density lipoprotein. These results suggest that the positive effects of n-3 fatty acid consumption on the atherosclerotic process could be linked in part to an increase in plasma membrane cholesterol efflux from vascular smooth muscle cells.
Assuntos
Colesterol/metabolismo , Ácidos Graxos Ômega-3/análise , Lipídeos de Membrana/fisiologia , Músculo Liso Vascular/fisiologia , Fosfolipídeos/química , Animais , Células Cultivadas , Ácidos Graxos não Esterificados/farmacologia , Músculo Liso Vascular/efeitos dos fármacos , RatosRESUMO
The phenotypic modulation and the enhanced proliferation of smooth muscle cells (SMC) as well as their foam transformation are major processes in arterial pathophysiology and during atherogenesis. Arterial SMC play a crucial role, in response to several stimuli: the SMC "activation" is an essential condition leading to the adult atherosclerotic plaque formation. Owing to the difficulty to study the SMC regulation in vivo, most of the literature in this field refers to in vitro models. Modulated SMC in culture, changing from a contractile to a synthetic state, share similar features with atherosclerotic plaques cells. The phenotypic modulation of SMC is expressed by morphological, biochemical, metabolic and functional modifications. The regulation of cholesterol movements might influence the foam transformation process of arterial SMC.
Assuntos
Colesterol/metabolismo , Músculo Liso Vascular/citologia , Animais , Células Cultivadas , Músculo Liso Vascular/metabolismo , Fenótipo , RatosRESUMO
The aim of this study was to elucidate signal transduction pathways following high-density lipoprotein 3 (HDL3) fixation to HDL high-affinity binding sites and leading to translocation of newly synthesized cholesterol to the plasma membrane pool for efflux. First, membrane phosphatidylcholine (PC) breakdown and 1,2-diacylglycerol (DAG) production were investigated following HDL3 or tetranitromethane (TNM)-HDL incubation with smooth muscle cells in culture. Second, newly synthesized cholesterol was labeled using [3H] mevalonolactone. Phospholipase C (PLC) and protein kinase C (PKC) were stimulated using carbachol and phorbol 12-myristate 13-acetate. Translocation and efflux of newly synthesized cholesterol were monitored using the cholesterol oxidase method and TNM-HDL as cholesterol acceptor. Results showed that: (1) native HDL3 but not modified HDL was able to stimulate PC breakdown and DAG formation; and (2) PLC and PKC stimulation using specific agents induce cholesterol translocation from intracellular to plasma membrane pool. Taken together, these two sets of results suggest that native HDL3 could induce cholesterol translocation by a PLC/PKC process in smooth muscle cells.
Assuntos
Lipoproteínas HDL/farmacologia , Músculo Liso Vascular/metabolismo , Fosfatidilcolinas/metabolismo , Proteína Quinase C/metabolismo , Esteróis/metabolismo , Fosfolipases Tipo C/metabolismo , Animais , Aorta Torácica/citologia , Aorta Torácica/efeitos dos fármacos , Aorta Torácica/metabolismo , Carbacol/farmacologia , Membrana Celular/metabolismo , Colesterol/biossíntese , Lipoproteínas HDL3 , Músculo Liso Vascular/citologia , Músculo Liso Vascular/efeitos dos fármacos , Ratos , Transdução de Sinais/efeitos dos fármacos , Estimulação Química , Acetato de Tetradecanoilforbol/farmacologiaRESUMO
OBJECTIVE: Increased plasma levels of plasminogen activator inhibitor-1 (PAI-1) have been suggested to be a part of the insulin resistance syndrome, and recent data suggest that adipose tissue participates in the production of PAI-1. We examined the expression and insulin regulation of subcutaneous adipose tissue PAI-1 mRNA and its relationship to insulin sensitivity. DESIGN: A cross-sectional study involving five lean (60.0+/-3.1 years, BMI 23.5+/-0.5 kg/m(2)) and six obese nondiabetic men (56.0+/-3.1 years, BMI 30.4+/-0.7 kg/m(2)), and six obese Type 2 diabetic men (61.4+/-3.2 years, BMI 31.8+/-1.0 kg/m(2)). MEASUREMENTS: Subcutaneous adipose tissue PAI-1 mRNA and insulin sensitivity were quantified using RT-competitive PCR and euglycemic hyperinsulinemic clamp technique, respectively. RESULTS: Subcutaneous adipose tissue PAI-1 mRNA levels were higher in obese nondiabetic and Type 2 diabetic men than in lean nondiabetic men. PAI-1 mRNA levels decreased in the three groups during a 240-min euglycemic hyperinsulinemic clamp (P<0.05 for all groups), and a similar reduction was observed during a 240-min saline control study indicating that adipose tissue PAI-1 gene expression has diurnal variation and is not acutely controlled by hyperinsulinemia. The basal PAI-1 mRNA levels correlated positively with BMI, and waist-to-hip ratio; and negatively with whole-body glucose disposal rate in nondiabetic men. CONCLUSIONS: Subcutaneous adipose tissue PAI-1 mRNA expression is increased in obese nondiabetic or in Type 2 diabetic men. Subcutaneous adipose tissue PAI-1 mRNA expression is increased in proportion to visceral obesity and to the level of whole-body insulin resistance. Subcutaneous adipose tissue PAI-1 mRNA expression is not acutely regulated by insulin, and it is subject to a diurnal variation.
Assuntos
Tecido Adiposo/metabolismo , Diabetes Mellitus Tipo 2/genética , Diabetes Mellitus/genética , Obesidade/genética , Inibidor 1 de Ativador de Plasminogênio/genética , Glicemia/metabolismo , Estudos Transversais , Diabetes Mellitus/fisiopatologia , Diabetes Mellitus Tipo 2/fisiopatologia , Técnica Clamp de Glucose , Humanos , Hiperinsulinismo , Masculino , Pessoa de Meia-Idade , Obesidade/fisiopatologia , RNA Mensageiro/análise , Valores de Referência , Pele , Transcrição GênicaRESUMO
Non-insulin-dependent diabetes (NIDD) is a situation at elevated risk for atherosclerosis. The plasma concentration of high-density lipoprotein (HDL) is often lowered. This may be accompanied by an abnormal composition and profile of HDL subfractions. These abnormalities might result in part from a defect in the net cholesterol ester transfer (CET) from HDL to apo B-containing lipoproteins. In the present work, we have studied the net CET and HDL conversion in normolipidemic, hypercholesterolemic, and hypertriglyceridemic NIDD, by comparison with control subjects. HDL conversion was determined by gradient gel electrophoresis after 23 h incubation in plasma with HDL3 labeled with a nontransferable synthetic marker. The net CET in normolipidemic NIDD was similar to that of controls, while it was approximately doubled in hypercholesterolemic or hypertriglyceridemic NIDD. In all groups, HDL conversion was comparable, with the exception of hypertriglyceridemic NIDD. In the latter group, the labeled HDL2/HDL3 ratio was increased, indicating a more complete conversion that was correlated with the triglyceride/cholesterol ester ratio in HDL. In addition, when lecithin:cholesterol acyl transferase was inhibited, a distinct peak of small HDL particles appeared in the density range of HDL2 in contrast with the other groups where only small HDL3 was formed. Recombination experiments showed that these abnormalities were attributable to the plasma in which labeled HDL3 was incubated rather than to the origin (control or hypertriglyceridemic NIDD) of labeled HDL3. These data suggest that in NIDD, hypertriglyceridemia may result in abnormalities of HDL conversion due to alterations in HDL composition.(ABSTRACT TRUNCATED AT 250 WORDS)
Assuntos
Ésteres do Colesterol/sangue , Diabetes Mellitus Tipo 2/sangue , Diabetes Mellitus Tipo 2/complicações , Hipercolesterolemia/sangue , Hipercolesterolemia/complicações , Hipertrigliceridemia/sangue , Hipertrigliceridemia/complicações , Lipoproteínas HDL/sangue , Arteriosclerose/etiologia , Transporte Biológico Ativo , Estudos de Casos e Controles , Humanos , Lipídeos/sangue , Lipoproteínas HDL2 , Lipoproteínas HDL3 , Masculino , Pessoa de Meia-Idade , Fatores de RiscoRESUMO
AIMS/HYPOTHESIS: Thiazolidinediones are new oral antidiabetic drugs that activate the nuclear receptor PPARgamma. Our aim was to identify potential target genes of PPARgamma in the human adipocyte in order to clarify how thiazolidinediones improve insulin sensitivity. METHODS: The effect of BRL 49653 (Rosiglitazone) on the mRNA expression of insulin receptor, insulin receptor substrate-1, p85alpha, p110alpha and p110beta subunits of phosphatidylinositol 3-kinase, Glut 4 and hormone sensitive lipase was examined in isolated adipocytes. Target mRNA levels were determined by RT-competitive PCR. RESULTS: The BRL 49653 (1 micromol/l) increased the mRNA concentrations of p85alphaPI-3 K (264 +/- 46 vs 161 +/- 31 amol/microg total RNA, p = 0.003) whithout affecting the expression of the other mRNAs of interest. This effect was dose-dependent (K0.5 = 5 nmol/l) and was reproduced by a specific activator of RXR, indicating that it was probably mediated by the PPARgamma/RXR heterodimer. The BRL 49653 also increased the amount of p85alphaPI-3K protein in adipose tissue explants (71 +/- 19%). In addition, BRL 49653 produced a more than twofold increase in insulin stimulation of phosphatidylinositol 3-kinase activity and significantly enhanced the antilipolytic action of insulin. CONCLUSION/INTERPRETATION: This work demonstrates that the gene of p85alphaPI-3K is probably a target of PPARgamma and that thiazolidinediones can improve insulin action in normal human adipocytes. Although the precise mechanism of action of BRL 49653 on PI3-Kinase activity is not completely clear, these findings improve our understanding of the insulin-sensitizing effects of the thiazolidinediones, possible drugs for the treatment of Type II (non-insulin-dependent) diabetes mellitus.
Assuntos
Adipócitos/fisiologia , Regulação da Expressão Gênica/fisiologia , Proteínas Musculares , Fosfatidilinositol 3-Quinases/genética , Proteínas Serina-Treonina Quinases , Receptores Citoplasmáticos e Nucleares/fisiologia , Tiazóis/farmacologia , Tiazolidinedionas , Fatores de Transcrição/fisiologia , Transcrição Gênica/fisiologia , Adipócitos/efeitos dos fármacos , Adipócitos/enzimologia , Tecido Adiposo/citologia , Tecido Adiposo/enzimologia , Células Cultivadas , Regulação da Expressão Gênica/efeitos dos fármacos , Transportador de Glucose Tipo 4 , Humanos , Hipoglicemiantes/farmacologia , Proteínas Substratos do Receptor de Insulina , Cinética , Proteínas de Transporte de Monossacarídeos/genética , Fosfatidilinositol 3-Quinases/metabolismo , Fosfoproteínas/genética , Fosforilação , Subunidades Proteicas , Proteínas Proto-Oncogênicas/genética , Proteínas Proto-Oncogênicas/metabolismo , Proteínas Proto-Oncogênicas c-akt , RNA Mensageiro/genética , Receptor de Insulina/genética , Rosiglitazona , Transcrição Gênica/efeitos dos fármacosRESUMO
BACKGROUND: An association with subcutaneous adipose tissue TNFalpha expression and insulin resistance has been suggested in obesity/type-2 diabetes, but this has not been examined directly. In the first part of the study we investigated whether this association is present in 7 lean, 10 obese nondiabetic and 9 type-2 diabetic men. In the second part of the study we examined the relationship between adipose tissue TNFalpha mRNA levels and BMI in 81 nondiabetic subjects spanning a wide range of BMIs. METHODS: Subcutaneous adipose tissue TNFalpha mRNA levels and insulin sensitivity were determined with quantitative RT-competitive PCR and hyperinsulinaemic clamp, respectively. RESULTS: Subcutaneous adipose tissue TNFalpha mRNA levels were similar in 7 lean and 10 obese nondiabetic and 9 type-2 diabetic men (P = 0.68), and did not change in response to 240-min hyperinsulinaemia. TNFalpha mRNA levels and insulin sensitivity were not correlated. Unexpectedly, no correlation between TNFalpha mRNA and BMI was found. The relationship between adipose tissue TNFalpha mRNA and BMI was examined further in 31 male and 50 female nondiabetic subjects. The subcutaneous adipose tissue TNFalpha mRNA level correlated with BMI in all subjects (rS = 0.32, P < 0.01), and in a subgroup analysis in men (rS = 0.55, P < 0.01) but not in women (rS = - 0.08). The correlation in men was dependent on a fourfold higher TNFalpha mRNA level in 5 morbidly obese men while there was no difference in TNFalpha mRNA levels in lean or obese men. CONCLUSIONS: Subcutaneous adipose tissue TNFalpha expression does not correlate with insulin sensitivity in nondiabetic or type-2 diabetic men; is not regulated by acute hyperinsulinaemia; and is increased only in morbidly obese men.
Assuntos
Tecido Adiposo/metabolismo , Diabetes Mellitus Tipo 2/fisiopatologia , Diabetes Mellitus/fisiopatologia , Resistência à Insulina , Obesidade/fisiopatologia , Transcrição Gênica , Fator de Necrose Tumoral alfa/genética , Glicemia/metabolismo , Índice de Massa Corporal , Diabetes Mellitus/genética , Diabetes Mellitus Tipo 2/genética , Feminino , Técnica Clamp de Glucose , Humanos , Resistência à Insulina/genética , Inulina/sangue , Inulina/farmacologia , Masculino , Pessoa de Meia-Idade , Obesidade/genética , RNA Mensageiro/genética , Reação em Cadeia da Polimerase Via Transcriptase Reversa , PeleRESUMO
BACKGROUND: PPAR gamma, leptin and TNF alpha are three major factors that play a key role in influencing adipocyte differentiation and both adipose tissue function and metabolism. However, the regulation of these three genes during a dynamic period of weight loss is unknown. We therefore investigated the concomitant regulation of the mRNA expression of PPAR gamma, leptin and TNF alpha in adipose tissue during a 21-day very low calorie diet (VLCD) in 12 non-diabetic obese women. METHODS: The mRNA levels of PPAR gamma, leptin and TNF alpha were quantified by quantitative RT-competitive PCR in abdominal subcutaneous adipose tissue before and during VLCD (940 kcal/day). RESULTS: VLCD induced weight loss (approximately 6 kg) and improved insulin sensitivity. Simultaneously, VLCD induced the reduction in the adipose tissue mRNA abundances of PPAR gamma (-13%, p < 0.05) and of leptin (-58%, p < 0.005), whereas TNF alpha mRNA levels increased (+78%, p < 0.005). PPAR gamma and leptin mRNA levels were correlated before (r = 0.778, p < 0.01) and after VLCD (r = 0.797, p < 0.01). Serum HDL-cholesterol concentrations were positively associated with PPAR gamma (r = 0.696, p < 0.03) and leptin (r = 0.806, p < 0.01) mRNA levels. CONCLUSIONS: The increase in TNF alpha mRNA levels suggested that a local increased expression of this cytokine in adipose tissue might play a role in the control of the fat mass during weight loss. PPAR gamma and leptin mRNA levels were positively associated both before and after VLCD, suggesting that common regulatory mechanism(s) might control their expression. More strikingly, we found strong positive correlations between circulating HDL-cholesterol and both PPAR gamma and leptin mRNA levels, suggesting the existence of physiological links between circulating lipoprotein metabolism and adipose tissue function.