DNA methylation in obesity and type 2 diabetes.

To elucidate the mechanisms related to the development of type 2 diabetes (T2D) and other degenerative diseases at a molecular level, a better understanding of the changes in the chromatin structure and the corresponding functional changes in molecular pathways is still needed. For example, persons with low birth weight are at a high risk for development of T2D later in life, suggesting that the intrauterine environment contributes to the disease. One of the hypotheses is that epigenetic regulation, including changes in DNA methylation leading to modifications in chromatin structure, are behind metabolic alterations, e.g. leading to the phenomenon termed metabolic memory. Altered DNA methylation has been shown to affect healthy aging and also to promote age-related health problems. There is suggestive evidence that lifestyle changes including weight loss can have an impact on DNA methylation and consequently gene expression. In this review we provide an overview of human studies investigating DNA methylation in obesity and T2D and associated risk factors behind these diseases.

Gene expression of peripheral blood mononuclear cells as a tool in dietary intervention studies: What do we know so far?

Peripheral blood mononuclear cells (PBMCs) generally refer to monocytes and lymphocytes, representing cells of the innate and adaptive immune systems. PBMCs are a promising target tissue in the field of nutrigenomics because they seem to reflect the effects of dietary modifications at the level of gene expression. In this review, we describe and discuss the scientific literature concerning the use of gene expression at the mRNA level measured from PBMCs in dietary interventions studies conducted in humans. A search of literature was undertaken using PubMed (last assessed November 24, 2011) and 20 articles were selected for discussion. Currently, results from these studies showed that PBMCs seem to reflect liver environment and complement adipose tissue findings in transcriptomics. PBMC gene expression after dietary intervention studies can be used for studying the response of certain genes related to fatty acid and cholesterol metabolism, and to explore the response of dietary interventions in relation to inflammation. However, PBMC transcriptomics from dietary intervention studies have not resulted yet in clear confirmation of candidate genes related to disease risk. Use of microarray technology in larger well-designed dietary intervention studies is still needed for exploring PBMC potential in the field of nutrigenomics.