Immunohistochemical Evaluation of Role of Serotonin in Pathogenesis of Psoriasis.

introductionPsoriasis is a common skin disorder characterized by erythaematosquamous papules and plaques. It is known to be associated with stressful and depressive disorders. Serotonin is a neurotransmitter that plays a role in the pathogenesis of inflammatory skin disorders.

aimTo evaluate the role of serotonin in pathogenesis of psoriasis. MATERIALS AND

methodsUsing standard immunohistochemical techniques, 24 biopsies from patients with chronic plaque psoriasis were examined together with 12 biopsies from age and gender-matched healthy subjects as a control group.

resultsBoth the percentage of positive cells (p=0.018) and H-score values (p=0.015) of serotonin expression were significantly higher in psoriasis compared to normal skin. H score of serotonin expression was significantly higher in cases with totally absent Granular Cell Layer (GCL) as opposed to those with thin/focally absent GCL (p=0.011), and in cases with moderate/strong epidermal inflammation compared to cases with mild inflammation (p=0.035). No significant correlation was detected between H score of cases and age, disease duration or Psoriasis Area and Severity Index (PASI) score.

conclusionSerotonin might play a role in development of psoriasis through its role as a growth factor promoting keratinocyte proliferation, and as mediator of inflammation and stimulant of T cell activation. It recruits T cells to sites of cutaneous inflammation and potentiate macrophage accessory function for T cell activation. Its expression is not related to the disease severity. Future large-scaled research on population of different ethnicities including other disease variants is needed. The use of serotonin receptor antagonists and serotonin reuptake inhibitors may be evaluated on wide-based studies to put the current observation into action.