Effect of Aspergillus fumigatus on the expression of tumor necrosis factor-α and activation of intracellular signaling molecule p38 mitogen-activated protein kinase by a human acute monocytic leukemia cell line THP-1 / 中华皮肤科杂志

ABSTRACT

Objective To evaluate the effect of Aspergillus fumigatus on the expression of tumor necrosis factor-α (TNF-oα) and activation of intracellular signaling molecule p38 mitogen-activated protein kinase (p38MAPK) in a human acute monocytic leukemia cell line THP-1.Methods Cultured THP-1 cells (2 x 105/ml) were divided into 4 groups to be treated with Aspergillus fumigatus suspensions at concentrations of 106 and 107 colony-forming units (CFU)/ml (106-and 107-CFU/ml Aspergillusfumigatus groups),100 mg/L β-glucan (a positive stimulus,β-glucan group),culture medium (blank control group) respectively for 1,3 and 6 hours.Real-time fluorescence-based quantitative PCR (qPCR) was conducted to determine the mRNA expression of TNF-α in the THP-1 cells in the above groups.Some other THP-1 cells were treated with 107 CFU/ml Aspergillusfumigatus suspensions (107-CFU/ml Aspergillusfumigatus group),β-glucan (β-glucan group) and culture medium (blank control group) separately for 24 hours,and enzymelinked immunosorbent assay (ELISA) was performed to detect the level of TNF-α in the culture supernatant of THP-1 cells.Western blot analysis was conducted to detect the levels of p38MAPK and phosphorylated p38MAPK in THP-1 cells after 15-,30-and 60-minute treatment with 107 CFU/ml Aspergillusfumigatus suspensions.After 2-hour incubation with the p38MAPK inhibitor SB203580 (20 μmol/L),some THP-1 cells were additionally treated with 107 CFU/ml Aspergillus fumigatus suspensions,β-glucan and culture medium separately for 6 hours,and those without SB203580 treatment served as the control group.Then,qPCR was performed to measure the mRNA expression of TNF-α in the THP-1 cells in the above groups.Results The mRNA expression of TNF-α significantly differed among the 106-and 107-CFU/ml Aspergillus fumigatus groups,β-glucan group and blank control group (F =110.983,P ＜ 0.001),and significantly increased over time (F =701.680,P ＜ 0.001).After 24-hour treatment with 107 CFU/ml Aspergillus fumigatus suspensions,the TNF-α level(6 236.30 ± 437.12 ng/L)significantly increased compared with the blank control group (132.10 ± 0.61 ng/L,P ＜ 0.01).Thirty minutes after the treatment with 107 CFU/ml Aspergillusfumigatus suspensions,the phosphorylated p38MAPK level significantly increased,but started to decrease at 60 minutes.The mRNA expression of TNF-α was significantly lower in the SB203580-treated Aspergillusfumigatus groups (3.83 ± 0.62) than in the SB203580-untreated Aspergillus fumigatus groups (187.23 ± 21.62).Conclusion After the treatment with Aspergillus fumigatus,human THP-1 cells can activate the signal molecule p38MAPK and secrete TNF-α,suggesting that monocytes may participate in the innate immune response to Aspergillusfumigatus infection.