Galectins and cutaneous immunity

Galectins are highly expressed in epithelial cells and immune cells. In skin, they can be detected in keratinocytes, melanocytes, dendritic cells, macrophages, and T cells. Galectins are present outside and inside the cells and thus may exhibit different functions through extracellular and intracellular actions. Galectins can be involved in the pathogenesis of inflammatory skin diseases by affecting growth, apoptosis, maturation, activation, and motility of keratinocytes and immune cells. Expression of galectins may change depending on the cellular status, such as proliferation and activation. For example, galectin-3 expression is upregulated in T cells but downregulated in dendritic cells when these cells are activated. Furthermore, their expression may also change under pathological conditions. Understanding the function of each galectin in keratinocytes and different immune cell types may reveal how galectins contribute to the pathogenesis of immune-mediated skin diseases.