Bikunin, a Serine Protease Inhibitor, Is Present on the Cell Boundary of Epidermis

The study demonstrated that bikunin, a serine protease inhibitor, was expressed in human epidermis, particularly in keratinocytes, hair follicles, and eccrine sweat glands. It was found on the cell boundaries of basal and spinous cell layers, but not in granular-horny layers, and was absent in apocrine sweat glands. The presence of bikunin was confirmed through mRNA analysis in HaCaT cells and human epidermal keratinocytes. The findings suggested that bikunin might play a role in regulating keratinocyte mitosis or inflammation and could contribute to skin and hair physiology by potentially regulating desmosomal dissociation during keratinocyte cell division.