All the cells in the human body have the same DNA but differ in gene expression, which is called gene regulation. Genes code for proteins that are needed for cellular functions. These proteins include biomarkers of skin aging like matrix metalloproteinases, sirtuins and interleukins. Information about the regulation of these proteins can be used to assess anti-aging properties of ingredients and cosmetic products. The genome consists of all of an organism’s genetic information encoded in DNA or RNA in the cases of viruses.
A microbiome is all the microbes in a defined habitat, their interactions with each other and their interactions with the host. A microbiome has transient and persistent elements. The skin performs many important functions, including the prevention of water loss, regulation of body temperature, protection from environmental insults and immunological functions. The skin’s microbiome contributes to this protective barrier through a variety of mechanisms including the exclusion of transients and pathogens by competing for nutrients and habitat. The skin microbiome also plays a role in many skin conditions including dandruff, acne, dermatitis and axillary odor.
A metagenome is comprised of all the genetic elements of the host and all those of all the microorganisms (microbiome) that live in or on that host.
Using a metagenomic approach, the Human Microbiome Project (HMP) was launched in 2008 by the National Institutes of Health. The HMP aims to define five human microbiomes including that of the skin. Future goals of the project intend to indentify the role of the human microbiome with disease and in maintenance of health. This will certainly bring new insights to cosmetic formulators.