Neurotrophins act as neuroendocrine regulators of skin homeostasis in health and disease

Neurotrophins regulate cutaneous innervation, act as growth and motility factors on structural skin cells such as keratinocytes and fibroblasts, modulate cutaneous immune function and even serve as stress mediators in skin biology. The multilayered neurotrophin interaction with skin biology through high affinity specific tyrosinekinase receptors and the Janus-faced p75 receptor, which depending on ligand and co-receptor expression can serve as a low-affinity pan-neurotrophin receptor or a high affinity proneurotrophin receptor, guaranties this neuroendocrine peptide family a central position in the control of skin homeostasis in health and disease. It is a challenging task for future research efforts to integrate our knowledge on differential neurotrophin expression patterns and signaling pathways into complex concepts of neuroendocrine tissue remodeling and pathogenetic processes. In addition, we need to improve our understanding of the role of neurotrophin processing enzymes, associated co-receptors and intracellular adaptor molecules in specific cutaneous cell populations to design precise interaction tools for research and treatment. Such tools will allow us to utilize this ancient growth factor family in the management of neurotrophin responsive pathogenetic pathways and cutaneous diseases such as neurogenic inflammation, peripheral nerve degeneration, wound healing, atopic dermatitis or psoriasis.