A Pilot Study of Gene Expression Analysis in Peripheral Blood Mononuclear Cells in Response to a Hypocaloric Mediterranean Diet

BACKGROUND: Few studies have examined gene expression in peripheral blood mononuclear cells (PBMCs) after a dietary intervention. OBJECTIVE: Our study is aimed at evaluating in a pilot study the peripheral blood gene expression in obese patients after weight loss secondary to a hypocaloric Mediterranean diet. DESIGN: A sample of 11 obese subjects without metabolic syndrome was enrolled. Biochemical, anthropometric parameters and microarray analysis were performed at baseline and after 6 months of dietary intervention. RESULTS: The mean age was 43.1 ± 6.3 years, and the mean body mass index (BMI) was 38.6 ± 8.1 kg/m(2). All the next improvements were statistically significant: body weight −7.4 ± 1.9 kg, BMI -2.5 ± 0.2 kg, fat mass −5.7 ± 1.2 kg, waist circumference −5.8 ± 1.2 cm, triglycerides −17.4 ± 6.5 mg/dl, C-reactive protein −3.1 ± 1.5 mg/dL, insulin −2.1 ± 1.0 mUI/L, and HOMA-IR −0.7 ± 0.2 units. We identified 634 differentially expressed genes: 262 genes with relative higher expression levels and 372 with lower expression levels. Cluster analysis showed 35 genes in nutritional disease and 17 genes in endocrine system. The most relevant gene was thyroid peroxidase (TPO), and this gene was overexpressed, and the next genes carbonic anhydrase VI (CA6), caveolin protein 1 (CAV1) and solute carrier family type 12 (SLLC12A3), soluble carrier family type 12 (SLLC12A3), beta 3 receptor (ADRB3), and glutamate receptor ionotropic N methyl D aspartate 2 A (GRIN2A) were all underexpressed. CONCLUSION: In PBMC from obese patients after a diet with a Mediterranean pattern, the expression of 634 genes, of the endocrine system and of nutritional disease, is modified.