Psoriasis is a chronic, systemic, inflammatory disorder which accelerates the life process of skin cells, based on a genetically induced deviant immune response. High-frequency ultrasonography (HF-USG) is a painless, non-invasive imaging technique that can be performed and repeated whenever the need arises. We evaluated lesional and non-lesional skin of psoriatic patients with the use of HF-USG, focusing on the immune-induced inflammation and skin thickness. Previous studies suggested that HF-USG, being a non-invasive technique, is useful as an aid to clinical evaluation of the severity of psoriatic plaques. Our goal was to determine whether the skin of psoriatic patients is influenced by the background or habits of the patients. The study included a total of 27 patients affected by psoriasis vulgaris. The thickness of the epidermis and dermis and the skin echogenicity were documented for the active plaques, as well as for the non-affected skin of all the patients included in the study, using a high-frequency ultrasonographic system. The patient's local background, sex, family history of psoriasis, smoking habits and sun exposure were analyzed. HF-USG of the psoriatic plaques exposes a three-band structure that is easily distinguished from the surrounding unaffected skin, due to a hypoechoic band in the upper dermis. Although not specific for psoriasis, it is a strong marker of inflammation. The obtained results confirm that, indeed, skin thickness is greater in lesional skin compared to non-lesional skin, by a mean of 1,180 µm (±340 µm). We consider that skin HF-USG should be used as a quantitative method in the clinical evaluation of the patients with psoriasis and may help as an objective means of assessing inflammation in lesional skin.

Psoriasis is a chronic, inflammatory disease with a complex pathogenesis that is not yet fully understood. Although it is a multifactorial disease, the genetic factor has a major role in the pathogenesis of psoriasis. Genome wide association studies have identified over 50 genetic loci associated with psoriasis risk. Beside TNF-α or IL-23, the IL-17 family is a newer group that has proven implications in the pathogenesis of psoriasis. The most important members of the family, with pro-inflammatory qualities, are IL-17A and IL-17F. These interleukins are produced by a varied number of cells, but by far the most important are Th17 cells. Of the patients 20-30% present moderate-to-severe psoriasis, therefore, systemic medication (phototherapy, methotrexate, cyclosporine, acitretin or biologic agents) is mandatory. The necessity of an individualized treatment plan, for each patient, is imperative in order to establish the best strategy for non-responders to classical treatment or to other biologic treatments. The discovery of Th17 pathway improved the treatment and prognosis of psoriasis. Anti-psoriatic agents against IL-17 or its receptors are a novel group of biologic agents; these include ixekizumab, secukinumab and brodalumab. Polymorphisms of IL-17 family have been correlated with the severity and response to treatment in psoriasis, and also with the risk of inflammatory, infectious, autoimmune or neoplastic pathologies. The significant difference in the presence or absence of susceptibility loci in different population is due to genetic background and environmental factors that have a major impact on disease predisposition. In this study, we reviewed the importance and influence of the IL-17 polymorphisms as predictors of response to treatment and severity of the disease.

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