| Budget Amount *help |
¥13,500,000 (Direct Cost: ¥13,500,000)
Fiscal Year 2006: ¥2,600,000 (Direct Cost: ¥2,600,000)
Fiscal Year 2005: ¥3,800,000 (Direct Cost: ¥3,800,000)
Fiscal Year 2004: ¥7,100,000 (Direct Cost: ¥7,100,000)
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| Research Abstract |
We studied the quorum sensing (QS) system and the related homoserine lactones (HSLs) observing Peudomonas aeruginosa invasion using the epithelial cell monolayer penetration assay model. Compared to the PAO1 wild-type, the QS mutants, ΔlasI and ΔrhlI, were compromised in its capacity to invade. The decreased invasiveness of Δ rhlI was restored by adding 100 μM exogenous C_4-HSL. However, the decreased invasiveness of an efflux mutant, ΔmexAB-oprM, was not restored in the presence of exogenous HSLs. The QS system partially plays a role in P. aeruginosa invasion ; however, C_4-HSL and 3-O-C_<12>-HSL are not the essential determinants for invasiveness for P. aeruginosa. The invasiveness of PAO1 WT was reduced in the presence of the efflux inhibitors (EPIs), MC-207,110 or D13-9001. In the presence of 1 μg/ml of EPIs, the invasiveness of PAO1 WT was slightly suppressed (not significant, P=0.69). On the other hand, in the presence of 10-100 μg/ml of EPIs, the invasiveness of PAO1 WT was significantly reduced in the concentration-dependent manner (P<0.01). The findings support that invasion determinant(s) are predominantly exported by P. aeruginosa via MexAB-OprM, and that the EPIs are useful to reduce not only antimicrobial resistance but also the invasiveness of P. aeruginosa.
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