Strangely, the IL-33 mRNA levels in the hippocampus of 5xFAD mice, an animal model of AD, were significantly lower than the levels for wild-type control mice, but otherwise, the IL-33 protein levels in the hippocampus of 5xFAD mice were significantly higher than the levels for wild-type control mice [25]. This evidence concerns the gene IL33 and Alzheimer disease.