The Human Micro Biome

“ Temporal shift in the skin microbiome associated with disease flares and treatment in children with atopic dermatitis”

By Kong et al.

The human microbiome is composed of microbes, as well as their genes and genomes that live on the human body. Scientists are learning just how important these microbes are to our health and well-being. There are billions of microbes that reside on the human skin, probably more than 10 billion microbial cells on each of us (Agnew). The skin microbiota plays an important role in the human immune functions and helping to defend its host against invading bacterial pathogens (Agnew).  Skin microorganisms perform a wide variety of functions that help out their host. Among these functions are overall immune system screening, tissue repair, wound healing, and inflammation control. Recent increase in allergic and (chronic) inflammatory diseases is a result of our modern western lifestyle, and that this is also associated with changes in the human microbiome (Zeeuwen et al). It has shown that people with atopic individual, compared with healthy individual have lower skin microbiota diversity, which correlate with lower environmental biodiversity in the surrounding (Zeeuwen et al).  

Atopic dermatitis is a chronic skin disease that affects a large portion of the world’s population. “Atopic dermatitis disorder is characterized by abnormalities in both skin barrier structures (e.g. filaggrin gene loss-of function mutations), a robust Th2-response to environmental antigens, possible deficiencies in innate immunity and a well-documented alternation of the skin microbiome” (Salava et al, 2014). Many of these abnormalities may occur as the consequence of epidermal dysfunction. It is comprised of three condition including asthma, allergies, and eczema. The characteristic of this disease includes skin rashes and itching. The skin becomes extremely itchy and inflamed, causing redness, swelling, cracking, weeping, crusting and scaling (Mary, 2012). Atopic dermatitis can occur at any time, but it mostly affects infects and young children. An important element of atopic dermatitis is the irritated sensation, because in response to this feeling, one starts to rub and scratch which makes the inflammation of the skin worse.

Skin microbiota is relevant to Atopic Dermatitis due to its relationship with disease progression. The study used a direct 16S rRNA gene sequencing method to determine that there is a topographic and temporal shift in the main bacterial species and bacterial diversity in the skin during the baseline, flare, and post-flare phases of Atopic Dermatitis. This means that the worsening of the disease severity is correlated with lower skin bacterial diversity as well as increased levels of Staphylococcus proportion. Staphylococcus Aureus popularly known as “staph” cause the immune system cells in the skin to react in a way that produce eczema like rashes. The release of the molecule, called delta toxin, by staph caused immune related mast cells in the skin to release tiny granules that cause inflammation (Kong et al, 2012). Therefore, in order to treat Atopic dermatitis, intermittent and active Atopic Dermatitis you have to increase the diversity of skin bacteria and decrease Staphylococcus proportions

The study also determined that most human bodies have stereotypical body distributions of Atopic Dermatitis; meaning that certain parts of the body favor specific bacteria growth as well as specific communities of microbes. Therefore, certain communities of microbes are important in the initiation and perpetuation of certain skin diseases. Thus, by globally examining bacterial communities, we are able to enhance beneficial microbes and microbial diversity in order to promote health and decrease Atopic Dermatitis flares. Increase in the proportion of Staphylococcus and reduction in microbial diversity precede worsening of AD severity. While it is clear that many of the dominant organisms (including Staphylococcus species) form a large part of the skin microbiome, very little is still understood of rare or transient organisms in atopic dermatitis. And, it is still unclear what factors are driving the changes in skin microbiome during flares of the disease (Salava et al. 2014).