Kallikrein-Related Peptidase 8-Dependent Skin Wound Healing Is Associated with Upregulation of Kallikrein-Related Peptidase 6 and PAR2

Kallikrein-related peptidase 8 (KLK8) is believed to be involved in the maintenance of skin homeostasis and pathogenesis of inflammatory skin diseases. Although previous studies have shown that KLK8 is expressed around incisional wounds, the exact role of KLK8 in wound healing remains obscure. In the present study, we compared wound healing in wild-type (WT) and Klk8 gene-disrupted (kallikrein-related peptidase 8 knockout, Klk8(-/-)) mouse skin. Wound healing in Klk8(-/-) mice was hampered with defective keratinocyte proliferation, differentiation, and migration in the early stages of wound healing. Compared with the prominent induction of Klk6 and protease-activated receptor 2 (PAR2) messenger RNA, and protein in WT mice after wounding, a much lower increase was observed in Klk8(-/-) skin. After skin wounding in WT mice, increased Klk6 was detected from the upper stratum spinosum to the stratum corneum. Moreover, in WT mice, Klk6 protein was processed. PAR2 was diffusely expressed in the cytoplasm of the stratum spinosum at day 7 post wounding in WT mice. These results suggest that Klk8 is involved in the proliferation and migration of keratinocytes through the upregulation and activation of Klk6 in the early stages of wound healing, and possibly in keratinocyte differentiation associated with the upregulation and activation of PAR2 in the late stages of wound healing.