PI3 kinase Inhibition Reduces Uptake of Haemophilus Influenzae by Airway Epithelial Cells

<b>Rationale:</b> The commonest cause of hospitalizations is exacerbations of COPD, with ~50% attributed to bacterial infection. Epithelial cells are able to internalise bacteria, which remain viable after antibiotic treatment and can recolonize following airway damage by oxidants or viruses. This is possibly via a phosphoinositide-3- kinase-dependent mechanism. To explore this, BEAS-2B bronchial epithelial cells were treated with a PI3K inhibitor and uptake of <i>Haemophilus influenzae</i> compared with effects of naturally occurring stilbenes resveratrol and isorhapontigenin, which also inhibit this pathway. <b>Methods:</b> BEAS-2B cells were pre-treated for 1h with resveratrol, isorhapontigenin (30μM), or the PI3K inhibitor LY29400 (10μM), prior to 48h exposure to fluorescently-labelled heat-killed <i>H. influenzae</i> (n=4). Extra-cellular fluorescence was quenched by Trypan blue and internal fluorescence measured fluorometrically. Cell viability was measured by MTT assay. <b>Results:</b> BEAS-2B cells ingested <i>H. influenzae</i> in a time-dependent manner (Fig. 1), with significant inhibition by all three compounds at 24 and 48h. There was no significant effect on cell viability at these time points. <b>Conclusion:</b> PI3K inhibition disrupts the ability of cells to engulf <i>H. influenzae</i> with similar effects seen with resveratrol and isorhapontigenin. Reducing bacterial uptake using natural products may be a useful novel therapy to reduce repeat exacerbations.