Is Ki-67, keratin 16, involucrin, and filaggrin immunostaining sufficient to diagnose inflammatory linear verrucous epidermal nevus? A report of eight cases and a comparison with psoriasis vulgaris

Adult-onset inflammatory linear verrucous epidermal nevus: Immunohistochemical studies and review of the literature

Adult-onset inflammatory linear verrucous epidermal nevus (ILVEN) is an uncommon cutaneous disease compared to childhood-onset ILVEN. The typical histopathologic features are alternating parakeratosis and orthokeratosis with an absent granular layer underneath parakeratosis, in contrast to a thickened granular layer below the foci of orthokeratosis in psoriasiform epidermal hyperplasia. Herein, we present a 49-year-old woman with typical clinical and histopathologic characteristics of adult-onset ILVEN, including linear arrangement of thick scaly papules and plaques localized on the medial side of her right leg, ankle, and foot. Immunohistochemical studies included involucrin, Ki-67, and keratin-10. Compared to the staining pattern in psoriasis, the expression of involucrin in this case was of lower intensity and localized to upper epidermal layers with relatively less extensive staining beneath regions of parakeratosis as compared to orthokeratosis; Ki-67 showed lower basal layer proliferative activity; and keratin-10 showed a greater intensity of staining within suprabasal epidermis.

Esculetin Ameliorates Psoriasis-Like Skin Disease in Mice by Inducing CD4+Foxp3+ Regulatory T Cells

Psoriasis is an autoimmune and inflammatory skin disease affecting around 2-3% of the world's population. Patients with psoriasis need extensive treatments with global immunosuppressive agents that may cause severe side effects. Esculetin, a type of coumarins, is an active ingredient extracted mainly from the bark of Fraxinus rhynchophylla, which has been used to treat inflammatory and autoimmune diseases in China. However, the antipsoriatic effects of esculetin have not been reported. In this study, we aimed to investigate the effects of esculetin on psoriatic skin inflammation in a mouse model and explored the potential molecular mechanisms underlying its action. We found that esculetin ameliorated the skin lesion and reduced PASI scores as well as weight loss in imiquimod-induced psoriasis-like mice, accompanied with weakened proliferation and differentiation of keratinocytes and T cell infiltration in esculetin-treated psoriatic mice. In addition, esculetin reduced the frequency of CD8⁺CD44^highCD62L^low effector T cells in psoriatic mice. In contrast, it increased the frequency of CD4⁺Foxp3⁺ Tregs in both lymph nodes and spleens of the psoriatic mice while promoting the differentiation of CD4⁺CD25^- T cells into CD4⁺Foxp3⁺ Tregs in vitro. Interestingly, depleting CD4⁺Foxp3⁺ Tregs largely reversed esculetin-mediated reduction in PASI scores, indicating that esculetin attenuates murine psoriasis mainly by inducing CD4⁺Foxp3⁺ Tregs. Furthermore, the mRNA levels of proinflammatory cytokines in the psoriatic mouse skin, including IL-6, IL-17A, IL-22, IL-23, TNF-α, and IFN-γ, were dramatically decreased by the treatment with esculetin. Finally, we found that esculetin inhibited the phosphorylation of IKKα and P65 in the psoriatic skin, suggesting that it inhibits the activation of NF-κB signaling. Thus, we have demonstrated that esculetin attenuates psoriasis-like skin lesion in mice and may be a potential therapeutic candidate for the treatment of psoriasis in clinic.