The Innate Immune System is the first defense system to protect against invading organisms, hence it’s very powerful presence in the epidermis. The skin is a host to normal microflora which is a colonization of bacteria that works with the innate immune system. Having a healthy microflora that works with the immune system protects the skin from invading pathogens that can cause harm to not only the skin, but the body itself. The second part of this defense system are the cells of the skin.
The keratinocytes and sebocytes also play a role in recognising invading pathohens by using pattern recognition receptors (PRC) such as toll-like receptors. Once this stimulation occurs, an amazing activation of chemical reactions takes place where the production of pro-inflammatory cytokines and anti-microbicidal peptides are released into extra cellular space. This communication between the keratinocyte cells, sebocytes and immune cells is crucial in defending the skin against harmful bacteria that causes skin infections.
The activation of pattern recognition receptors by keratinocyte cells and sebocytes is directly involved in the induction of antimicrobial peptides.
So what are Antimicrobial Peptides?
Antimicrobial Peptides are crucial in maintaining the immunity of the skin by protecting against pathogens as well as maintaining healthy skin barrier homeostasis. Antimicrobial peptides are a very diverse group of cationic polypeptides that release a large spectrum of cytotoxic actions that destroy bacteria, viruses and fungi.
During the inflammatory stages, the keratinocyte cells are the main cellular sources of antimicrobial peptides and their levels are equivalent with the susceptibility of skin infections.
Acne & Antimicrobial Peptides
Antimicrobial peptides are found to be at very high levels in both acne and rosacea patients/clients. These high levels of AMPs leads to the realisation that they are important mediators in acne skin infections. Both keratinocyte cells and sebocytes release large quantities of AMPs in response to bacterial proteins such as P.acnes.
These groups of molecule peptides attract other classes of inflammatory cells such as T-cells, monocytes and macrophages which when recruited increase the level of antimicrobial peptides hence increasing inflammation.
Growing evidence supports the role of antimicrobial peptides and their receptors in the development of acne. It is important that we as clinicians have a good understanding of how the skin`s innate immune system functions so that we can effectively treat acne skin and inflammation.