Elevated serum TNF-alpha level as a link between endothelial dysfunction and insulin resistance in normotensive obese patients.
OBJECTIVE
The aim of the study was to analyse the role of tumour necrosis factor-alpha (TNF-alpha) in insulin resistance and endothelial dysfunction in patients with different types of obesity.


METHODS
Fasting serum TNF-alpha immunoreactive concentration (enzyme-linked immunosorbent assay, ELISA) and bioactivity (L929 cell cytotoxicity assay), endothelin-1 and C-peptide levels (radioimmunoassay, RIA) were measured in 15 patients with android- and 13 patients with gynoid-type obesity and 15 lean healthy controls with normal glucose tolerance and blood pressure.


RESULTS
Significantly (P<0.01) higher TNF-alpha concentration (8.92 +/- 0.44 pg/ml) and bioactivity (3.12 +/- 0.48 U/ml) were found in patients with android obesity as compared to patients with gynoid obesity (7.01 +/- 0.30 pg/ml, 0.97 +/- 0.11 U/ml) and to the lean controls (6.88 +/- 0.26 pg/ml, 0.88 +/- 0.08 U/ml). Serum endothelin-1 (5.38 +/- 0.30 pg/ml) and C-peptide levels (4.82 +/- 0.71 ng/ml) were also significantly higher (P < 0.01) in patients with android-type obesity than in controls (3.89 +/- 0.43 pg/ml, 1.46 +/- 0.25 ng/ml, respectively). In patients with gynoid-type obesity, only the C-peptide levels proved to be significantly higher (2.84 +/- 0.29 ng/ ml). Endothelin-1 levels, although were found to be slightly higher, did not differ statistically from in controls (4.56 +/- 0.31 pg/ml). There were significant positive linear correlations only in patients with android-type obesity between TNF-alpha, body mass index (BMI), serum endothelin-1 and C-peptide levels.


CONCLUSIONS
TNF-alpha may be one of the factors contributing to insulin resistance and vascular dysfunction in patients with android obesity.
Winkler
G
G
Department of Internal Medicine St John's Hospital, Budapest, Hungary.
Lakatos
P
P
Salamon
F
F
Nagy
Z
Z
Speer
G
G
Kovács
M
M
Harmos
G
G
Dworak
O
O
Cseh
K
K
D000328:Adult; D015992:Body Mass Index; D002096:C-Peptide / Q000097:blood; D016022:Case-Control Studies; D019332:Endothelin-1 / Q000097:blood; D004730:Endothelium, Vascular / Q000503:physiopathology*; D004797:Enzyme-Linked Immunosorbent Assay; D006801:Humans; D007333:Insulin Resistance; D016014:Linear Models; D009765:Obesity / Q000097:blood / Q000503:physiopathology*; D014409:Tumor Necrosis Factor-alpha / Q000378:metabolism*
D002096:C-Peptide; D019332:Endothelin-1; D014409:Tumor Necrosis Factor-alpha