Altered tissue expression pattern of cell adhesion molecules, ICAM-1, E-selectin and VCAM-1, in bullous pemphigoid during methotrexate therapy

Little is known about how eosinophils accumulate in bullous pemphigoid (BP) and why these cells rapidly disappear during immunosuppressive therapy. Eosinophils can produce cytokines such as IL-4, IL-5, IL-6, IL-10 and IL13, which can induce endothelial cells to express cellular adhesion molecules (CAMs) such as E-selectin, vascular cell adhesion molecule-1 (VCAM-1) and intercellular adhesion molecule-1 (ICAM-1) necessary for the recruitment of eosinophils from the bloodstream to the skin. The present aim was to investigate the cellular expression of these three CAMs in serial biopsies before and during oral low-dose methotrexate therapy. Seventy-four biopsy specimens, 37 from active lesions and 37 from normal skin, were taken at different intervals from eight patients with bullous pemphigoid and stained immunohistochemically with specific monoclonal antibodies for these three CAMs. The expression and distribution of CAMs in the biopsies was evaluated and scored with light-microscopic examination. The basal keratinocytes in active lesions expressed ICAM-1. A strong VCAM-1 expression of endothelial cells and pericytes was correlated to a perivascular inflammatory cell infiltrate that also showed intense immunoreactivity to ICAM-1. Endothelial cell/pericytes also expressed E-selectin strongly in the BP patients before therapy. The expression of CAMs faded during therapy and, to the best of our knowledge, this has not been previously reported. Thus we suggest that the rapid reduction of tissue eosinophils may reflect the altered pattern of cell adhesion molecules during immunosuppressive therapy, which could explain the prompt clinical improvement seen in BP patients treated with methotrexate.