The Effect Of Neutrophil Respiratory Burst On Mucoid Pseudomonas Aeruginosa Biofilm And Alginate Production

Objective:To explore the effect of neutrophil respiratory burst on the mucoid Pseudomonas aeruginosa biofilm?P.a BF?and alginate production in vivo.Methods:Rat model of mucoid P.a BF infection was established through endotracheal intubation and these rats were randomly divided into2 groups:BF-PMA group?promoted neutrophil respiritory burst group?and BF-control group?control group?,then sacrified on the third day.Tubes were drawn out to investigate the BF structure with scanning electron microscopy and detect the content of bacterial count.The contents of alginate was detected through sulphuric acid-oxybenzene method and the mRNA expression of important genes involved in synthesis of alginate such as algD,algB,algU and algR were detected by RT-PCR.Meanwhile histopathological changes of lung tissues were investigated by HE straining and the levels of IFN-?and IL-10 in serum were determined by enzyme-linked immunosorbent assay?ELISA?.Results:The bacterial count in the BF-PMA group(2.35±0.53×10⁵CFU.tube^-1)was significantly higher than that of the BF-control group(0.70±0.28×10⁵ CFU.tube^-1,P<0.05).And the BF structure of the BF-PMA group was more complex and thicker compared to that of the BF-control group.Alginate production in the BF-PMA group(104.47±47.84 mg.g^-1)was significantly higher than that of the control group(29.32±10.21 mg.g^-1,P<0.05),and the BF of the BF-PMA group also exhibited higher expression of alg genes than BF of the BF-control group did?P<0.05?.Pathological changes of lung tissues in the BF-PMA group were more serious than those in the BF-control group.The level of IFN-?in the BF-PMA group?134.98pg.ml-1?was higher than that of the BF-control group?124.20 pg.ml-1,P<0.05?,and the ratio of IFN-?to IL-10 was also higher in the BF-PMA group?2.08±0.19?than that of the BF-control group?1.85±0.09,P<0.05?.Conclusion:Promoted neutrophil respiratory burst might make the elimination of mucoid P.a BF more difficult by enhancing alginate production through upregulating alg genes expression,accompanied by more severe pathological damages in lung and inflammatory responses.