In this study we also provide novel preliminary evidence that PU.1 and Nrf2 cooperatively bind DNA in a zinc-dependent fashion, as reflected by supershift assays presented in this study. Although this evidence is not conclusive that the GM-CSF and ARE signaling pathways are coordinately regulated, such a possibility is certainly intriguing and suggests that zinc bioavailability is crucial to regulate both of these related defense systems within the lung (and perhaps, in other tissues) during significant inflammatory and/or oxidative stresses. This would seem reasonable from a teleological perspective for immune and anti-oxidant defense to be coordinately regulated in the alveolar space, where microbial invasion and oxidative stress are constant threats. These findings are interesting but raise many more questions and highlight some of the limitations of this particular study. First, we were not able to directly test the effects of PU.1 and Nrf2 signaling in vivo in our Klebsiella pneumonia model. Therefore, we can only speculate that restoration of PU.1 and Nrf2 signaling through zinc supplementation is mechanistic in improving bacterial clearance. Additionally, we did not detect any zinc-dependent interactions
