Dectin-1, a C-type lectin receptor, participates in the killing of Candida albicans by human neutrophils: an experimental study / 中华皮肤科杂志

ABSTRACT

Objective To investigate whether human neutrophils kill Candida albicans through recognition of insoluble β-glucan in cell walls of C.albicans (CalG) by dectin-1,a C-type lectin receptor.Methods Neutrophils were obtained from peripheral blood of healthy human subjects and cultured in vitro.Real-time PCR was carried out to quantify the mRNA expressions of dectin-1 and Toll-like receptor 2 (TLR2) in neutrophils challenged with CaIG of 100 mg/L for 1,6,and 24 hours.A Fluoro hydrogen peroxide (H2O2) detection kit was used to determine H2O2 levels in some neutrophils exposed to CaIG (100 mg/L) for 15 minutes,2 hours,6 hours,as well as in some neutrophils preincubated with laminarin (a dectin-1 inhibitor) of 100 mg/L and 50 mg/L for 30 minutes followed by challenge with CaIG of 100 mg/L for 2 hours.Colony forming units (CFUs) were counted after the incubation of C.albicans with neutrophils pretreated with laminarin of 100 mg/L and 50 mg/L for 30 minutes.Results The relative mRNA expression level of dectin-1 was 2.8195 + 0.1669,5.4859 + 0.7244 and 3.6041 + 0.5372 in neutrophils challenged with CaIG for 1,6 and 24 hours,respectively,significantly higher than that in unchallenged neutrophils at these corresponding time points (all P ＜ 0.01).The level of H2O2 was (64.55 + 15.67),(290.34 + 30.56),and (208.54 ± 26.88) μ mol/L respectively in neutrophils treated with CaIG for 15 minutes,2 hours,and 6 hours respectively,compared to (22.05 ± 3.99) μmol/L in untreated neutrophils (all P ＜ 0.01).The pretreatment with laminarin of 100 and 50 mg/L attenuated the release of H2O2 in CaIG-treated neutrophils by 73％ ((80.45 + 22.41) μ mol/L,P＜ 0.01) and 45％ ((130.42 + 44.55) μmol/L,P＜ 0.01),respectively,compared with neutrophils treated with CaIG only.The fungicidal activity of neutrophils against C.albicans was also significantly inhibited by pretreatment with laminarin of 50 and 100 mg/L (both P＜ 0.01).Conclusions Dectin-1 may be involved in the secretion of H2O2 as well as killing of C.albicans by human neutrophils,which may provide a preliminary evidence for adoptive transfer of neutrophils as an approach to the treatment of systemic C.albicans infection.