Recently, it was demonstrated that organic dust extract-induced airway hyperresponsiveness, neutrophil influx and cytokine/chemokine production were nearly absent in MyD88 knockout mice, suggesting that acute organic dust-induced airway inflammatory response is highly dependent on MyD88 signaling, and is dictated by important contributions from upstream TLRs (32). This evidence concerns the gene MYD88 and airway hyperresponsiveness.