[The effect of recombinant panton-valentine leukocidin on the production of cytokines by human alveolar macrophages].
OBJECTIVE
To investigate the effect of recombinant panton-valentine leukocidin (rPVL) on the regulation of human alveolar macrophage CD14 and IL-10 and TNF-alpha.


METHODS
Human alveolar macrophages (AM) were purified and cultured from bronchoalveolar lavage fluid. Each sample was divided into groups according to different concentrations and exposure times of rPVL. Semi-quantitative RT-PCR was used to evaluate the CD14 mRNA levels and Double-antibody-sandwich-ELISA was used to measure the IL-10 and TNF-alpha levels in AM cultures.


RESULTS
CD14 mRNA decreased after rPVL treatment in time-and concentration dependent manners. There were no statistically significant differences in CD14 mRNA among the blank control groups (F = 1.708, P > 0.05). CD14 mRNA in the T6N10 group and the T6N100 group( T = time in hours, N = concentration of rPVL/nmol/L) decreased as compared to the T6N0 group (t = 4.132, 6.818, both P < 0.001), and that in the T24N10 group and the T24N100 group also decreased as compared to the T24N0 group (t = 7.401, 11.415, both P < 0.001), indicating that the expression of CD14 was downregulated by rPVL treatment. There were also statistically significant differences in CD14 mRNA between T6N10 and T24N10 groups, T6N100 and T24N100 groups (t = 4.692, 6.019, both P < 0.001), T6N10 and T6N100 groups, T24N10 and T24N100 groups (t = 2.686, 4.014, P < 0.01 respectively), indicating that the expression of CD14 decreased as the treatment time and the concentration of rPVL increased. The IL-10 concentrations of the T24N10 and T24N100 groups increased as compared to the T24N0 group (t = 4.036, 3.941, both P < 0.01) in time-dependent and concentration-dependent manners with rPVL treatment. The TNF-alpha concentration of the T24N10 group decreased while that of the T24N100 group increased as compared to the T24N0 group (t = 2. 824, 8. 468, both P < 0.01, respectively), indicating that a lower concentration of rPVL inhibited TNF-alpha release while a higher concentration of rPVL induced release of TNF-alpha.


CONCLUSIONS
The results suggest that rPVL could reduce the expression of CD14 and induce disordered release of anti-inflammatory and proinflammatory cytokines by AMs, which may be one of the important mechanisms underlying the high mortality of infection with PVL-positive Staphylococcus aureus.
Wu
Ben-quan
BQ
Department of Respiratory Medicine, The Third Affiliated Hospital, Sun Yat-sen University, Guangzhou 510630, China.
Shi
Yun-feng
YF
Huang
Jing
J
Liu
Hui
H
Zhang
Wen-xian
WX
Zhou
Feng-li
FL
Zhang
Tian-tuo
TT
D001427:Bacterial Toxins / Q000633:toxicity*; D002478:Cells, Cultured; D005098:Exotoxins / Q000633:toxicity*; D006801:Humans; D016753:Interleukin-10 / Q000096:biosynthesis; D007956:Leukocidins / Q000633:toxicity*; D018950:Lipopolysaccharide Receptors / Q000096:biosynthesis; D016676:Macrophages, Alveolar / Q000378:metabolism*; D014409:Tumor Necrosis Factor-alpha / Q000096:biosynthesis
D001427:Bacterial Toxins; D005098:Exotoxins; D007956:Leukocidins; D018950:Lipopolysaccharide Receptors; C078284:Panton-Valentine leukocidin; D014409:Tumor Necrosis Factor-alpha; D016753:Interleukin-10