TNF and Alzheimer disease: There were (i) direct correlations between polymorphonuclear cells in the bronchoalveolar fluid and cerebral soluble amyloid-β1–40 (p = 0.0033), and several Alzheimer’s disease-relevant neuroinflammatory biomarkers including cerebral TNF-α and IL-6; (iii) significant decreases in blood-brain barrier permeability in mechanically ventilated Alzheimer’s disease mice and a trend towards increased blood-brain barrier permeability in mechanically ventilated wild-type mice.