title: The role of toll-like receptors in host defenses and their relevance to dermatologic diseases.
abstract: The family of toll-like receptors (TLRs) plays a central role in the cutaneous immune defense system. To date, different TLRs have been found on several major cell populations of the skin, such as keratinocytes, fibroblasts, antigen-presenting cells, and melanocytes. Activation of TLRs leads, via different intracellular signaling pathways, to the production of pro-inflammatory stimuli, and is considered a danger signal that should transform the skin in to the functional state of defense. However, TLRs have also been implicated in tissue homeostasis and renewal. Within the group of TLRs, two types have been identified: surface-expressed TLRs, which are predominantly active against bacterial cell wall compounds; and intracellular receptors, which preferentially recognize virus-associated pattern molecules. In addition, surface-expressed receptors trigger phagocytotic and maturation signals, while the intracellular TLRs lead to the induction of antiviral genes. Our review aims to outline the importance of TLRs in the pathogenesis of numerous skin diseases and the potential of TLR agonists as a treatment option for various skin diseases.
authors.affiliation: Department of Dermatology and Allergy, Charité-Universitätsmedizin Berlin, Berlin, Germany.
authors.forename: Dorothea
authors.initials: D
authors.lastname: Terhorst
authors.forename: Behnam Naderi
authors.initials: BN
authors.lastname: Kalali
authors.forename: Markus
authors.initials: M
authors.lastname: Ollert
authors.forename: Johannes
authors.initials: J
authors.lastname: Ring
authors.forename: Martin
authors.initials: M
authors.lastname: Mempel
mesh_terms: D000152:Acne Vulgaris / Q000276:immunology; D000938:Antigen-Presenting Cells / Q000276:immunology; D001327:Autoimmune Diseases / Q000276:immunology; D015415:Biomarkers / Q000378:metabolism; D001899:Borrelia Infections / Q000276:immunology; D003876:Dermatitis, Atopic / Q000276:immunology; D003879:Dermatologic Agents / Q000627:therapeutic use; D005347:Fibroblasts / Q000276:immunology; D006801:Humans; D015603:Keratinocytes / Q000276:immunology; D007918:Leprosy / Q000276:immunology; D008544:Melanocytes / Q000276:immunology; D011565:Psoriasis / Q000276:immunology; D015398:Signal Transduction / Q000276:immunology; D012867:Skin / Q000276:immunology* / Q000378:metabolism; D012871:Skin Diseases / Q000188:drug therapy / Q000276:immunology* / Q000378:metabolism; D013587:Syphilis / Q000276:immunology; D051193:Toll-Like Receptors / Q000819:agonists / Q000276:immunology*
chemical_list: D015415:Biomarkers; D003879:Dermatologic Agents; D051193:Toll-Like Receptors