Current and Future Therapies for Psoriasis with a Focus on Serotonergic Drugs

Psoriasis is a chronic immune-mediated skin disease, with a pathogenesis resulting from a combination of genetic and environmental factors. The pathogenesis of psoriasis is driven by the interaction between innate and adaptive immune cells and keratinocytes, in a complex process mediated by cytokines and other signaling molecules. This leads to an inflammatory process with increased proliferation of epidermal cells, neo-angiogenesis, and infiltration of white cells in the skin, which cause the characteristic psoriasis plaques. Several studies have suggested that the neurotransmitter serotonin, a key mediator between the skin and the neuroendocrine system, also plays an important role in the pathogenesis of psoriasis. Psoriasis often needs long-term treatment, which can be a burden. Thus, the choice of the treatment is crucial to increase the patients' adherence and quality of life. This review addresses the currently available systemic and topical treatments for psoriasis, used by themselves or combined with phototherapy. It particularly focuses on the importance of advanced drug delivery systems as a way to increase the drug penetration and retention in the skin, while also enhancing its solubility and stability. Finally, we discuss the role of the serotonin system in psoriasis, and summarize what is known about the effects of antidepressants, in particular specific serotonin reuptake inhibitors, on the physical symptoms of this disease.