Skin Germs and Immune System Help Each Other

Everyone has a diverse population of microbes living on their skin, known as the skin microbiome. Prior research done by University of Pennsylvania researchers highlighted the diversity of bacteria living on the skin with DNA-based sequence analysis of the bacterial genomes. Now, the group has been able to include the immune system and how it influences the bacterial populations and vice versa. The complement system is a branch of our immune system that interacts with the skin microbiome. It functions as a molecular alarm and can lead attacks on microbial assaults by marking cells for elimination. In their most recent study, researchers adjusted levels of the C5aR protein, a key receptor in the inflammatory function of the complement system. By inhibiting C5aR in mice and comparing this group to an untreated group, the team discovered that the microbial diversity changed in the treated animals, throwing off the balance of “good” and “bad” microbes. They also observed that genes associated with immune surveillance in the complement system were downregulated in the treated animals, showing a strong link and communication between microbiome diversity and the immune system. This symbiotic relationship seems to help maintain healthy skin. A disruption or imbalance in the system might be the cause of diseases such as eczema or psoriasis. More research in this area could lead to findings making it possible to monitor and adjust complement activity in patients to treat disease.