Role of ERK Pathway in the Pathogenesis of Atopic Dermatitis and Its Potential as a Therapeutic Target.

Atopic dermatitis (AD) is an eczematous skin disorder characterized by type 2 inflammation, barrier disruption, and intense itch. In addition to type 2 cytokines, many other cytokines, such as interferon gamma (IFN-γ), interleukin 17 (IL-17), and interleukin 22 (IL-22), play roles in the pathogenesis of AD. It has been reported that the extracellular signal-regulated kinase (ERK) is downstream of such cytokines. However, the involvement of the ERK pathway in the pathogenesis of AD has not yet been investigated. We examined the expression of p-ERK in mouse and human AD skin. We also investigated the effects of the topical application of an ERK inhibitor on the dermatitis score, transepidermal water loss (TEWL), histological change, and expression of filaggrin, using an AD-like NC/Nga murine model. The effects of an ERK inhibitor on filaggrin expression in normal human epidermal keratinocytes (NHEKs) and on chemokine production from bone marrow-derived dendritic cells (BMDCs) were also evaluated. p-ERK was highly expressed in mouse and human AD skin. Topical application of an ERK inhibitor alleviated the clinical symptoms, histological changes, TEWL, and decrease in expression of filaggrin in the AD-like NC/Nga murine model. The ERK inhibitor also restored the IL-4 induced reduction in the expression of filaggrin in NHEK, and inhibited chemokine production from BMDC induced by IL-4. These results indicate that the ERK pathway is involved in the pathogenesis of AD, and suggest that the ERK pathway has potential as a therapeutic target for AD in the future.

Two Cases of Angiosarcoma with Persistent Unilateral Eyelid Swelling.

Angiosarcoma is a widely known neoplasm with one of the poorest prognoses; however, such cases are rarely observed by the ophthalmologists in clinical practice. The tumor commonly develops on the face and scalp and may cause eyelid swelling. We present 2 such cases. Case 1 was an 82-year-old woman who presented with indulated swelling of the right eyelid that extended to the upper forehead. Biopsy revealed a poorly circumscribed tumor infiltrated throughout the dermis and fat tissue, exhibiting both angiomatous and solid patterns. Immunohistochemistry showed CD31(-) and D2-40/podoplanin(+), suggesting angiosarcoma. The patient had multiple lung metastases and died 14 months later. Case 2 was a 77-year-old man who presented with swelling of the left eyelid, and erythema on the left temporal skin developed ulcerated nodules. Biopsy showed proliferated tumor cells in a sheet form, extensively throughout the dermis. Angiosarcoma was preferred based on immunohistochemistry: CD31(+), CD34(+), and D2-40(-). The patient was treated with electron beam therapy and chemotherapy and died after 13 months. It would be difficult for an ophthalmologist to suspect such a rare neoplasm only from swelling of the eyelids. However, angiosarcoma should be considered if the swelling spreads steadily from a head rash with a nodule or ulcer nearby.