Trichoscopy as a Monitoring Tool for Activity and Remission in Pemphigus Vulgaris: A Clinical Study Supported by Immunological Evaluation.

Overview

Pemphigus vulgaris (PV) is a potential life-threatening autoimmune bullous disorder presenting with multiple erosions and flaccid blisters that can involve both mucous membrane and skin. The microscopic findings include intraepithelial blisters caused by acantholysis of keratinocytes as the consequence of autoantibody formation. The antibodies are mainly IgG autoantibodies mostly directed against desmoglein 1 and 3 (Dsg 1, 3), which are adhesion molecules expressed on the surface of keratinocytes.

Scalp is a unique location for pemphigus because of the abundance of desmogleins localized in hair follicles. The frequency of scalp involvement in the course of pemphigus is estimated at 16-60% . According to literature data, the scalp is the first location in 9-15% of patients with pemphigus. Several cases of alopecia in the course of pemphigus have been described. The significance of the distribution of desmogleins in hair follicles for scalp involvement and a potential use of direct immunofluorescence of plucked hairs are discussed in the literature. The significance of scalp involvement for the course of pemphigus remains controversial. Trichoscopy is a non-invasive method for diagnosing hair and scalp disorders. Trichoscopy is widely used to differentiate causes of scalp lesions and scarring and non-scarring alopecia. To date there are few studies on the value of trichoscopy in pemphigus. The pathogenesis and pathophysiology of PV depend on various factors like cellular immunity, genetic factors, ethnicity, diet and environment. According to previous studies, Dsg autoantibodies with IgG1 and IgG4 subtypes are mostly detected in the active form of the pemphigus diseases. Accordingly, the significant role of autoreactive B cells in the pathogenesis of PV could be explained by producing these types of autoantibodies. Recently attention has been directed toward the role of T cells in the pathogenesis of PV. Similar to other autoimmune diseases, the underlying etiology of PV depends on the interaction between T cells and B cells resulting in antibody secretion. Autoreactive CD4+ T cells are essential for the pathogenesis of several ab-mediated autoimmune diseases by providing help to autoreactive B cells resulting in the production of antigen specific auto-ab. Alterations in several T cell subsets like CD4+CD25+ Treg and Th17 cells, have been described and are suggested to play a role in the pathogenesis of pemphigus. A few studies have investigated the significant role of T cell subgroups, namely regulatory T cells (Treg), T helper17 (Th17), and T follicular helper cells (Tfh) in PV and some studies were carried out on both human and mouse models to meticulously reveal the function of T cell phenotypes including CD8+T cells, γδ T cells, and resident memory T cells in the pathogenesis of PV, which may explain the wide range of clinical presentations and severity of PV in patients.