Keratinocytes play a role in the immunity to Herpes simplex virus type 2 infection

Herpes simplex virus type 2 (HSV-2) infection is the most common cause of genital ulcerative disease in the developed world. Keratinocytes are the primary cells involved in clinical lesions caused by HSV-2. In our study, we intensively examined cytokine expression in the HSV-2-infected keratinocytes. We observed upregulation of a series of cytokines including early-induced antiviral cytokines as interferons α, β (IFN-α, β), tumor necrosis factor α (TNF-α), colony stimulating factors (CSFs) as G-CSF, GM-CSF, interleukin 3 (IL-3), growth factors (EGF, KGF, and IGF-β1), defensins, selectins, leukocyte function-associated antigens (LFAs,) and toll-like receptors (TLR-2, 3, 4, and 9). More importantly, we found that HSV-2-infected keratinocytes stimulated the proliferation of lymphocytes in co-cultivation system. These data suggest that keratinocytes participate in the immune response to HSV-2 infection in two ways. They secrete inflammatory cytokines to resist the HSV-2 infection directly and recruit the immune cells to eliminate the primary infection indirectly and enhance the adaptive immunity to prevent subsequent infections.