The role of toll-like receptors in the pathophysiology of acne

Acne vulgaris is a common cutaneous disorder of the pilosebaceous follicle, affecting more than 45 million people in the United States alone. The pathogenesis of acne is multifactorial, involving abnormal hyperkeratinization, increased sebum production, hormones, cutaneous microbes, and immunological mechanisms. Many of the immunological processes that contribute to the formation of acne lesions take place at the very site of disease, the skin. Skin is an important component of the innate immune system, providing both physical barriers and rapid cellular responses by keratinocytes, Langerhans cells, and other infiltrating inflammatory cells. In this review, we discuss the ability of the innate immune system to use Toll-like receptors (TLRs) to recognize microbial patterns and initiate immune responses in cutaneous disorders. Because TLRs are vital players in infectious and inflammatory diseases, they are potential therapeutic targets. Indeed, the ability of TLRs to combat disease already has been harnessed through the development of drugs that act as TLR agonists. A better understanding of TLRs will allow for the development of new therapeutic options for cutaneous inflammatory diseases such as acne.