3.1 Genetics of the human host

Recent research has identified that the genetic make-up of the human host can directly influence the microbiome, and vice versa.

As you will see in Video 2 below, human genetic material is composed of extremely long molecules of deoxyribonucleic acid (DNA), located in the nucleus of the cell. Within the DNA molecules are shorter sequences, called genes, which form the ‘recipe’ for the manufacture of proteins, which control many of the essential processes within the human host. However, the proteins that the human host produces can also affect the functioning of the gut microbiome. What’s particularly interesting is that recent evidence has shown that the gut microbiome can actually change which proteins are made by the human host cells. For example, the gut microbiome can affect which proteins are made by the cells of the gut wall, and this has an impact on digestion of food and the immune response to pathogens that enter the gut. Exactly how the microbiome is controlling which proteins are made by the human host cells is still not very well understood, but evidence suggests that this is through epigenetics (Alenghat, 2013). As Video 2 explains, epigenetics is the addition or removal of chemical groups from the DNA molecule, which helps to control which proteins are made in a cell at any given time.

The finding that the microbiome can affect epigenetic regulation of the human DNA is important for health. Epigenetic changes are highly dynamic and known to be important in regulating numerous important processes within the cells. Altered epigenetic regulation of genes is also linked to a number of health conditions, such as cancers, autoimmune disorders, neurodegenerative disorders, stress and mental health disorders. It is also well known that changes in epigenetic control of the DNA can pass down through successive generations within a family, so this may be an important target for improving health of not only the individual but their subsequent offspring.