Study of leptin and adiponectin as disease markers in subjects with obstructive sleep apnea.

BACKGROUND: Published studies showed conflicting results of the associations between adiponectin and leptin levels and obstructive sleep apnoea (OSA). In obese patients, plasma leptin is elevated and adiponectin is decreased, and we postulate that these adipokines could be potential markers of clinical and metabolic perturbations in patients with OSA. METHODS: 147 patients with suspected OSA had polysomnography to determine the Respiratory Disturbance Index (RDI). We measured fasting plasma glucose (FPG), fasting serum insulin, plasma leptin, adiponectin, and full lipid profile. Patients were classified on the basis of the RDI, degree of adiposity, and insulin resistance (IR) (homeostasis model assessment of insulin resistance (HOMAIR)). RESULTS: 28.6% of subjects had normal polysomnography, 34.8% had mild OSA, 19.6% had moderate OSA, and 17% had severe OSA. Obesity was more prevalent in subjects with moderate-severe OSA (47%). Adiponectin decreased significantly (P = 0.041) with increasing severity of OSA. Though BMI was significantly higher in subjects with severe OSA, paradoxically, leptin was lowest in those subjects independent of gender dimorphism. CONCLUSIONS: Adiponectin is an independent marker of disease severity in patients with OSA. The paradoxical decrease in circulating leptin, which suggests impaired secretion, deserves further studies as a potential marker of severe OSA.

Associations of adipokines & insulin resistance with sex steroids in patients with breast cancer.

BACKGROUND & OBJECTIVES: Several studies have suggested an important, but conflicting and controversial role for adipose tissue mass in breast cancer risk. Factors such as insulin-like growth factors, sex steroids, adipokines and obesity-related inflammatory markers have been postulated as potential effectors of the mechanisms by which obesity and associated metabolic disorders influence breast cancer risk. In this study we evaluated the associations between obesity indices, insulin resistance, circulating adipokines, sex steroids and breast cancer. METHODS: Fasting adiponectin, leptin, insulin resistance (homeostasis model assessment, HOMA-IR), testosterone, estradiol, sex hormone binding globulin (SHBG), LH and FSH were determined in 144 newly-diagnosed histologically confirmed breast cancer patients and 77 controls. Univariate and multivariate regression analyses were used to find the associations of these variables with each other, indices of obesity and with breast cancer. RESULTS: BMI, waist circumference, HOMA-IR and leptin were significantly (P<0.001) higher in patients than in controls. Adiponectin level was also significantly (P<0.05) higher in patients compared to controls. Adiponectin and leptin showed significant correlations with insulin and HOMA-IR but only adiponectin was significantly correlated with estradiol and SHBG. Logistic regression analyses showed that factors associated with breast cancer were BMI [OR (95% CI) =2.8 (1.4-5.5), P=0.004]; high levels of adiponectin [5.1 (2.2-11.5), P<0.001); hyperinsulinaemia [1.1 (1.0-1.1), P=0.01], leptin [3.1 (1.7-5.7), P<0.0001], estradiol [2.5 (1.3-4.7), P=0.005] and testosterone [1.3 (1.03-1.7), P=0.03]. INTERPRETATION & CONCLUSIONS: Our findings confirm that adipokines, insulin resistance and sex steroids are associated with breast cancer. The paradoxical association of increased adiponectin with breast cancer is a novel finding that deserves further investigation.

Putative roles of circulating resistin in patients with asthma, COPD and cigarette smokers.

AIMS: To investigate the hypothesis that circulating resistin reflects the degree of pulmonary inflammation, this study explores putative roles of resistin in patients with acute and stable inflammatory obstructive airway diseases and cigarette smokers. METHODS: We determined complements C3, C4, fasting resistin, insulin, glucose and lipid profile; calculated insulin resistance (homeostasis model assessment (HOMA-IR) in patients with acute asthma exacerbation (n=34); stable asthma (n=26) and stable chronic obstructive pulmonary disease (COPD; n=26), cigarette smokers (n=81), and healthy control subjects (n=42). We determined the associations between these variables and pulmonary function tests. RESULTS: Patients with COPD, acute and stable asthma had significantly higher resistin and insulin than control subjects. Resistin, insulin, HOMA-IR, FEV1% and FEV1/FVC were significantly (p< 0.05) different between patients with acute asthma compared with stable asthma and COPD; smokers had similar levels of resistin, C3 and C4 as patients with asthma and COPD. In smokers, patients with asthma or COPD, resistin showed significant inverse correlations with FEV1%; FEV1/FVC% and positive significant correlations with BMI and HOMA-IR. Logistic regression showed that resistin is associated (p< 0.05) with inflammatory obstructive airways disease - odds ratio (OR)=1.22 and smoking OR=1.18. CONCLUSION: Resistin may be a disease activity marker and may contribute to insulin resistance in smokers, asthma and COPD.