Microflora has Ten Times the Number of Human Cell Count

Our view of human biology and human diseases has been modified by the ongoing acquisition of knowledge about the human microbiome. Although we have always been vaguely aware that the human body is host for many microorganisms indeed, only new For_Mikrobiom_General Skinscientific technologies, like the DNA sequence analysis, could finally reveal in detail the vast and complex communities of microorganisms which are resident in and on the human body.

It has been calculated that a human adult houses about 10 to the power of 12 bacteria on the skin, 10 to the power of 10 in the mouth, and 10 to the power of 14 in the gastrointestinal tract. With a number of approximately 10 to the power of 14 cells, the human microflora outnumbers our own body cells by a factor of ten. It is representing thousands of bacterial, viral, and fungal species, which are all required for both a normal human development and a lifelong health.

(Graph: Matthias Reiger)

(Graph: Matthias Reiger)

Human-Environment Interaction as an Important Health Factor

On the one hand, early life interactions between the developing immune system and microbes shape the outcome of our immune reactions in later life, resulting in a predisposition for or protection from allergic and autoimmune diseases.

On the other hand, bacterial homeostasis on our bodies´ surfaces is constantly maintained throughout adult life, whereas an imbalance of the microbial flora can lead to a partial pathogen overgrowth.

S. Aureus Influences the Course of Atopic Dermatitis

Several lines of evidence point out to a microbial involvement in the pathogenesis of atopic dermatitis (AD), a chronic relapsing disorder affecting equally children and adults with worldwide prevalence rates of 1-20 %. AD incidents have increased markedly over the past three decades, presumably by the influence of environmental components.

The profiling of patients´ bacterial microbiota via 16S rRNA gene sequencing indeed confirmed increases in Staphylococcus aureus relative abundance during AD flares together with a decrease in bacterial diversity.

Which Cutaneous Dysfunctions are Worth Considering?

One aim of the microbiome research area at the Institute of Environmental Medicine, under the guidance of Professor Claudia Traidl-Hoffmann, is to develop better descriptions of changes in the microbiota of affected skin sites during flares.

This aim is realized in a large cohort study of CK-CARE at the moment. First results provide new and deeper insights in the course of flares and help clarifying whether or in what way clinically different subtypes of AD vary in their respective microbiome.

In this cohort study, the main focus lies on the natural course of an allergic disease to create a better understanding of the pathology of atopic eczema. The differences and similarities between the patients´ examination results will serve as a first basis for further studies.

The chief aim must be to elucidate the role of barrier dysfunctions and to identify whether S. aureus colonization is the cause or the result (or even both) of changes in the host´s skin microbiome. Because it is known that a reduction of a S. aureus prevalence leads to a reduction of flares, we are currently researching new ways to restore the individually normal and diverse microflora.

(Graph: Matthias Reiger)

(Graph: Matthias Reiger)

Bacteria and Skin Cells are Interacting

Another important aim of our microbiome team is to study the interaction between the human skin immune system and the microorganisms living within this environment.

Skin commensal bacteria modulate skin immune cell functions and induce protective For _Mikro_Symbiosis in Skinimmunity to pathogens. On the one hand, detecting those bacteria which are also recognized by the skin immune system helps to differentiate the diversity of beneficial and pathogenic bacteria. On the other hand, the conduction of in-vitro experiments, with the target to determine the functions of single bacteria or a set of them on human skin cells, leads to a fuller understanding of the respective interaction mechanisms.Changes in the microbiome during the immune system restauration of HIV-patients are likely promising for future examinations of the interrelatedness between microbiome and human cells.

Our special focus is on the gut and the skin microbiome because there probably exists a connection between the gut microbiota and skin health, potentially through stimulation and/or education of immune cell populations.

The Aim is the Reduction of the AD-risk

There is evidence that the gastrointestinal microbiota plays a major role in the interaction between microbiota in general and the immune system. Low diversity in the gut microbiota during early infancy has been associated with a follow-up development of atopic eczema later in life. Therefore, we involve neonates and children in our studies in order to find ways of preventing them from AD.

Existing Cooperations

  • Tom Clavel, PhD, Juniorgroup leader
  • Peter Bauer, Professor