Human β-Defensin-2 Expression by Keratinocytes is Induced by Co-Culture with Trycophyton rubrum Through Toll-Like Receptors 2 and 4

Abstract

To determine a role of human β-Defensin-2 (HBD-2) in defense against cutaneous dermatophyte infection, we investigated the induction of HBD-2 mRNA expression by a nontumorigenic human keratinocyte-derived cell line, HaCaT cells, after co-culture with microconidia collected from the colonies of Trichophyton rubrum. Co-culture of T. rubrum or Candida albicans with HaCaT cells significantly induced HBD-2 mRNA expression. Furthermore, treatment with anti-TLR2 or TLR4 antibodies inhibited T. rubrum-induced HBD-2 upregulation, while it did not affect C. albicans-induced HBD-2 upregulation. Pretreatment of T. rubrum with Concanavalin A, which blocks mannosyl and glucosyl residues, inhibited HBD-2 expression by HaCaT cells, suggesting that mannosylated and glycosylated residues are important for HBD-2 induction. Collectively, these results suggest that T. rubrum induces HBD-2 expression through TLR2 and/or TLR4 pathway in keratinocytes and that HBD-2 may play a defense role in cutaneous dermatophyte infection.