Connective tissue Collagen VII protects the skin from harmful bacteria

New study provides insights into the innate immune defense of the skin

Researchers at Freiburg University Hospital are finding a possible approach to the treatment of butterfly disease. The key role in this approach is the connective tissue protein collagen VII. So far, the protein was only as an anchor of stability of the skin, but the research group showed in a recent study that collagen VII also plays a central role in the innate immune system. That the connective tissue protein also occurs in the spleen and the lymphatic organs and has important functions there, was previously unknown.

In particular, patients with dystrophic epidermolysis bullosa (EB), better known as butterfly disease, could benefit from the current study results. Collagen VII is absent in EB patients, which can lead to tearing of the skin and blistering at the least stress. The scientists were able to prove in mice that the protein occurs not only on the skin, but also in the spleen. From there, Collagen VII controls the intensity with which immune cells attack bacteria. The results of the study have been published in the journal Proceedings of the National Academy of Sciences (PNAS) and may lead to a better understanding and new therapies for the butterfly disease.

New study establishes a link between the connective tissue protein Kollagen VII and the immune system of the skin. (Image: Ольга Тернавская / fotolia.com)

A completely new player in the control of the immune system

"It is now clear that connective tissue molecules such as collagen VII are active components of the innate immune system," says Dr. Alexander Nyström, research group leader of the study in a press release. This brings a completely new player in the control of the immune system on the plan. Without the connective tissue protein, the skin becomes more bacterially colonized and infections can occur. This was also confirmed in the blood test of 30 patients affected by the butterfly disease. Previously, doctors and scientists believed that the many wounds and mechanical sensitivity of the skin of butterfly patients were responsible for the increased bacterial colonization.

The protein cochlin enhances the innate immune response

Comparisons of mice that failed to form collagen VII with healthy animals showed that collagen VII occurs in the spleen, where it binds and releases the protein cochlin. Cochlin in turn enhances the innate immune response. In animals that could not form collagen VII, the level of cochlin in the blood was also significantly lowered. The blood test in 30 human patients gave the same results. An artificial supply of collagen VII into the spleen of the animals led to a normalization of the cochlin value. As a result, the bacterial colonization of the skin was reduced. Even a cochlear diet improved the immune response.

The bacterial balance of the skin is not well understood

According to the University Hospital Freiburg, the skin is also colonized by numerous bacteria in healthy people. These are important for our health and take over protective functions. Incorrect bacterial colonies can also cause diseases such as skin infections. At worst, bacteria on the skin can even help support skin cancer development. How the balance of "good" and "bad" bacteria is maintained on the skin, so far not well understood. (Fp)