Regulatory T cells (Tregs), which are characterized by expression of the transcription factor Foxp3, are a dynamic and heterogeneous population of cells that control immune responses and prevent autoimmunity. We recently identified a subset of Tregs in murine skin with properties typical of memory cells and defined this population as memory Tregs (mTregs). Due to the importance of these cells in regulating tissue inflammation in mice, we analyzed this cell population in humans and found that almost all Tregs in normal skin had an activated memory phenotype. Compared with mTregs in peripheral blood, cutaneous mTregs had unique cell surface marker expression and cytokine production. In normal human skin, mTregs preferentially localized to hair follicles and were more abundant in skin with high hair density. Sequence comparison of TCRs from conventional memory T helper cells and mTregs isolated from skin revealed little homology between the two cell populations, suggesting that they recognize different antigens. Under steady-state conditions, mTregs were nonmigratory and relatively unresponsive; however, in inflamed skin from psoriasis patients, mTregs expanded, were highly proliferative, and produced low levels of IL-17. Taken together, these results identify a subset of Tregs that stably resides in human skin and suggest that these cells are qualitatively defective in inflammatory skin disease.

Biologic fatigue may be most frequent in those patients using infliximab. Further studies are needed to identify risk factors associated with biologic fatigue and to develop meaningful antidrug antibody assays.

Alopecia areata is considered to be a T-cell mediated autoimmune disease of the hair follicle. Current immunosuppressive approaches and immunomodulatory treatment with contact sensitizers such as diphenylcyclopropenone and squaric acid dibutylester are dealt with in this review article. The efficacy of the various modes of treatment is evaluated by a review of literature and their mode of action is discussed. In accordance with the mechanism of autoimmune pathogenesis of AA, improved future treatments may be immunosuppressive or immunomodulatory, or they should otherwise protect the hair follicle from the injurious effects of the inflammation. Such possible future therapeutic approaches include the use of liposomes as an improved vehicle, application of immunosuppressive cytokines like TGF-beta and IL-10, inhibition of apoptosis mediated by the Fas-FasL system, inhibition of the lymphocyte homing receptor CD44v10, induction of tolerance as well as principles of gene therapy.

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IntroductionPalmoplantar psoriasis (PP) and palmoplantar pustulosis (PPP) are diseases affecting the hands and/or feet that can cause marked physical discomfort and functional disability. The tumor necrosis factor-alpha antagonists adalimumab, etanercept, and infliximab, the interleukin (IL)-17A inhibitors ixekizumab and secukinumab, and the IL-23 or IL-12/IL-23 inhibitors guselkumab and ustekinumab have been well studied for the treatment of moderate to severe plaque psoriasis. Less is known about the efficacy and safety of these agents for the treatment of PP (hyperkeratotic and pustular forms) and PPP. The aim of this review was to investigate the efficacy of biologic therapy for the treatment of hyperkeratotic PP, pustular PP, and PPP.MethodsA systematic search of the medical electronic databases (Medline, Embase, and Cochrane Library) was conducted to identify studies or case reports which both used biologic therapy for the treatment of hyperkeratotic PP, pustular PP, and PPP and reported treatment outcomes.ResultsThe systematic search identified 579 published articles, of which 44 were included in the analysis. Seven of the articles involved randomized placebo-controlled trials, two were open label trials, and the remaining were cohort studies, case series, or case reports. In the randomized controlled trials on the treatment of hyperkeratotic PP, adalimumab, guselkumab, infliximab, ixekizumab, and secukinumab each demonstrated superiority to placebo at 16, 16, 14, 12, and 12 or 16 weeks, respectively (p < 0.05). For the treatment of pustular PP, ustekinumab 45 mg was not superior to placebo at 12 and 16 weeks, respectively (p > 0.05), although an open label study demonstrated that four of five patients on a therapeutic regimen of ustekinumab 90 mg achieved clinical clearance at 16 weeks. For the treatment of PPP, etanercept and ustekinumab 45 mg were not superior to placebo at 12 and 16 weeks, respectively (p > 0.05). A combined analysis of studies for hyperkeratotic PP demonstrated that 94.7%, 90.0%, 82.5%, 89.1%, and 86.7% of patients experienced an improvement of at least 50% upon treatment with adalimumab, guselkumab, ixekizumab, secukinumab, and ustekinumab, respectively. In a combined analysis of case reports examining PPP, infliximab showed the greatest efficacy at 100.0% clinical improvement of patients from case reports, followed by ustekinumab at 58.8% clinical improvement. Few serious adverse events were reported, but several were reported in patients treated with infliximab or secukinumab.ConclusionBiologic therapy is effective and well-tolerated for the treatment of hyperkeratotic PP, but less data are available on the treatment of pustular PP or PPP. Adalimumab, guselkumab, ixekizumab, secukinumab, and ustekinumab all showed > 80% efficacy for the treatment of hyperkeratotic PP, while infliximab and ustekinumab showed moderate efficacy for the treatment of pustular PP, and infliximab was the most efficacious treatment for PPP.Electronic supplementary materialThe online version of this article...