Acne vulgaris: role of the immune system.

Acne vulgaris is a worldwide condition that has a complex pathophysiology. The knowledge of this pathology is clear in its four classic principles based on the pilosebaceous unit; there exists hyperkeratinization of its duct, increase of sebum production, anaerobic bacterias, and inflammatory response. However, new findings have explained the relationship that occurs inside the acne lesion. The immune system has a key role since it is stimulated by the other participants involved, such as phylotypes of Propionibacterium acnes (P. acnes), antimicrobial peptides (AMPs), sebaceous glands (SGs), matrix metalloproteinases (MMPs), and other immune system pathways.