IL6 and Alzheimer disease: Positive staining for TNF-α (Fig 8; black arrows) was observed in the alveolar epithelium of both WT and AD mice at 12 h after LPS challenge but not before LPS challenge (0 h), and positive staining for IL-6 was observed in the alveolar epithelium at 12 h after LPS challenge; weaker (although still positive) staining was also observed in the alveolar epithelium before LPS challenge (Fig 8).