Abstract:

Objective To investigate the effect of peptidoglycan from Staphylococcus aureus on the release of several chemokines including interleukin 8 （IL-8）, regulated upon activation, normal T cell expressed and secreted （RANTES）, macrophage-derived chemokine （MDC） by normal human epidermal keratinocytes （KCs） and the role of Toll-like receptor 2 （TLR2） in this process. Methods KCs were derived from the foreskin of a healthy boy and propagated. After 2 - 4 passages, KCs were collected and treated with various concentrations （3, 10, 30 and 100 mg/L） of peptidoglycan for 24 hours or with peptidoglycan of 100 mg/L for varying durations （3, 6, 12, 36 hours）. A fraction of KCs were pretreated with functional grade purified anti-TLR2 monoclonal antibody before the treatment with peptidoglycan of 100 mg/L. After additional 12-hour culture following the treatment, enzyme linked immunosorbent assay was used to detect the level of IL-8, RANTES and MDC in culture supernatants of KCs. Results KCs spontaneously released IL-8 and RANTES. Peptidoglycan increased the production of IL-8 but decreased that of RANTES by KCs. The levels of IL-8 were 209.96 ± 10.31 ng/L, 250.28 ± 9.52 ng/L, 285.11 ± 10.28 ng/L, 359.40 ± 6.93 ng/L in KCs treated with peptidoglycan of 3, 10, 30, 100 mg/L, respectively, compared to 135.41 ± 14.37 ng/L in untreated KCs （all P < 0.05）. On the contrary, a significant decrement was seen in the secretion of RANTES by KCs treated with peptidoglycan of 10, 30, 100 mg/L compared with untreated KCs （110.72 ± 8.51 ng/L, 90.50 ± 2.45 ng/L, 49.89 ± 13.74 ng/L vs 149.94 ± 18.71 ng/L, all P < 0.05）. The monoclonal antibody to TLR-2 could markedly suppress the promotion of IL-8 production by peptidoglycan, but had no obvious influence on the inhibition of RANTES production by peptidoglycan. MDC could not be detected in the culture supernatants of KCs with or without peptidoglycan stimulation. Conclusion Peptidoglycan could inhibit RANTES secretion but induce IL-8 production by KCs likely via TLR2.