Figure 1. Tsr chemoreceptor mediates E. coli adherence to human lung epithelial cells.

BEAS-2B and A549 cells were cultured on glass cover slips until fully confluent. Indicated strains of E. coli were added to the monolayer of the epithelial cells at same multiplicity of infection (MOI = 5) and co-cultured in absence or presence of recombinant human IL-8 (rhIL-8, 1 μg/ml). After 6 h incubation, the wells were thoroughly washed to remove the free bacteria. The BEAS-2B cells and the bacteria adhered onto or internalized into the cells were illustrated by immunofluorescence staining of E-cadherin in red and E. coli LPS in green (Scale bar 10 μm). (a) The numbers of bacteria adhered on BEAS-2B cells (b) and on A549 cells (c) were counted from 6 fields (400 x) in each condition, and are shown as mean ± SE. The adherence and internalization of E. coli was further confirmed by detection of LPS in the cell lysates using Western Blot. RP437: the native strain of E. coli; UU2599: Tsr knockout strain; UU2373: Tsr expression only strain. *p < 0.05 vs. Vehicle for the same strain, respectively; ^†p < 0.05 vs. RP437 and UU2373 in the rhIL-8 treated-conditions, respectively.