The Brain–Skin Axis in Psoriasis—Psychological, Psychiatric, Hormonal, and Dermatological Aspects

Abstract

Psoriasis is a chronic inflammatory skin disease with systemic manifestation, in which psychological factors play an important role. The etiology of psoriasis is complex and multifactorial, including genetic background and environmental factors such as emotional or physical stress. Psychological stress may also play a role in exacerbation of psoriasis, by dysregulation of the hypothalamic–pituitary–adrenal (HPA) axis, sympathetic–adrenal–medullary axis, peripheral nervous system, and immune system. Skin cells also express various neuropeptides and hormones in response to stress, including the fully functional analog of the HPA axis. The deterioration of psoriatic lesions is accompanied by increased production of inflammatory mediators, which could contribute to the imbalance of neurotransmitters and the development of symptoms of depression and anxiety. Therefore, deregulation of the crosstalk between endocrine, paracrine, and autocrine stress signaling pathways contributes to clinical manifestations of psoriasis, which requires multidisciplinary approaches.

Mast cells as important regulators in the development of psoriasis

“…Psoriasis is regulated by the brain–skin axis. The HPA axis is involved in the development of psoriasis by the release of CRH, ACTH, and glucocorticoids, and these regulate the skin response to stress and the topical immune response ( 100 ). MCs express CRHR1 in proximity of psoriatic plaques, and elevated CRH in psoriasis induces the degranulation of MCs.…”

Roles of Infection in Psoriasis

“…Therefore, more research is needed in the future to focus on the direct relationship between infectious factors and psoriasis. In the treatment of psoriasis, nanotechnology enhances the efficiency of local drug delivery and limits the systemic use of immunosuppressive drugs by improving drug penetration [4,29]. If nanotechnology can be used to deliver infection-controlling drugs, it could be a viable and efficient way to treat psoriasis in the future.…”

“…Several studies have shown that pro-inflammatory cytokines in psoriasis, such as IL-6, IL-17, and TNF-α, are associated with psychiatric disorders [27,28]. Second, the microbiota-gut-brain axis can be the potential bridge between infection or microbiota dysbiosis and psychiatric or psychological problems [29]. Patients with depression and anxiety exhibit disturbances in the gut microbiota [30,31].…”

Chronic skin ultraviolet irradiation induces transcriptomic changes associated with microglial dysfunction in the hippocampus

“…Bidirectional communication between the skin and brain regulates local and global homeostasis in the body [ 1 ]. The skin is the first barrier located at the interface with the external environment, and it senses, collects, and responds to environmental stimuli (such as oxidative stress, ultraviolet (UV) and infrared radiation, and pollution) [ 2 ]. Skin converts these external stresses into cellular signals.…”