Stress, the neuroendocrine system and mast cells: current understanding of their role in psoriasis

Psychological stress can activate the hypothalamic–pituitary–adrenal axis and sensory nerves in the brain and skin, resulting in the release of neuroendocrine and neural mediators such as, corticotropin-releasing hormone, neuropeptides, neurotrophins and α-melanocyte-stimulating hormone. These factors can activate mast cells to release proinflammatory mediators and some of them, for example, histamine, tryptase and nerve growth factor, can stimulate sensory C-fibers. Since corticotropin-releasing hormone, sensory nerves and mast cell numbers are increased in the psoriatic lesion, a feedforward loop can exist potentiating the inflammation. Studies in rats and mice have shown that mast cells are activated during standardized stress through corticotropin-releasing hormone and sensory nerves. Therefore, the role of stress, the neuroendocrine system and mast cells in psoriasis is discussed in this article.