APP and Alzheimer disease: We then conducted a flow cytometric analysis of brain cells after Aβ staining with methoxy-X04, in which depletion of intestinal bacteria remarkedly decreased both percentage of Aβ-positive CD11b+ brain cells and the mean fluorescence intensity (mFI) of CD11b+ cell population in APP-transgenic mice (Figure 7, d – f; t test, p < 0.05), apparently indicating that microglial internalization of Aβ did not contribute to cerebral Aβ clearance in gut bacteria-depleted AD mice.