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Although tight junctions between human brain microvascular endothelial cells in the blood–brain barrier prevent molecules or cells in the bloodstream from entering the brain, in Alzheimer’s disease, peripheral blood monocytes can “open” these tight junctions and trigger subsequent transendothelial migration. However, the mechanism underlying this migration is unclear. Here, we found that the CSF2RB, but not CSF2RA, subunit of the granulocyte-macrophage colony-stimulating factor receptor was overexpressed on monocytes from Alzheimer’s disease patients. CSF2RB contributes to granulocyte-macrophage colony-stimulating factor-induced transendothelial monocyte migration. Granulocyte-macrophage colony-stimulating factor triggers human brain microvascular endothelial cells monolayer tight junction disassembly by downregulating ZO-1 expression via transcription modulation and claudin-5 expression via the ubiquitination pathway. Interestingly, intracerebral granulocyte-macrophage colony-stimulating factor blockade abolished the increased monocyte infiltration in the brains of APP/PS1 Alzheimer’s disease model mice. Our results suggest that in Alzheimer’s disease patients, high granulocyte-macrophage colony-stimulating factor levels in the brain parenchyma and cerebrospinal fluid induced blood–brain barrier opening, facilitating the infiltration of CSF2RB-expressing peripheral monocytes across blood–brain barrier and into the brain. CSF2RB might be useful as an Alzheimer’s disease biomarker. Thus, our findings will help to understand the mechanism of monocyte infiltration in Alzheimer’s disease pathogenesis.

The photosynthetic performance of variegated leaves can be very important in the cultivation and management of variegated plants. Actinidia kolomikta (Rupr. & Maxim.) Maxim. leaves have striking color variation. To clarify the variegated leaf type and photosynthetic cost, we measured leaf structure and ultrastructure, spectral properties, chlorophyll fluorescence and net photosynthetic rate (Pn). The study was conducted in Jilin during spring, summer, and fall in 2013. Leaf anatomy and ultrastructure were observed with light and electron microscopy. Leaf reflectance and pigment content were measured with a Unispec spectrometer and high performance liquid chromatography. Photosynthetic characterization was performed with a photosynthesis system and plant efficiency analyzer. In the palisade tissue of variegated areas, intercellular spaces were found, and cells contained fewer and abnormally developed chloroplasts. Normal chloroplasts were distributed mostly in spongy tissue. The reflectance of the adaxial surface was higher in variegated leaves than in green leaves. The Pn of variegated leaves was 80 to 94% of green leaves, the maximum photosystem II efficiency of the adaxial and abaxial surfaces in variegated leaves was similar to green leaves, and the quantum use efficiency of the abaxial surface was higher than the adaxial surface in variegated leaves. These results show that the photosynthetic performance of variegated leaves was retained well. Thus, variegated leaves are not a limiting factor for cultivation and application in A. kolomikta, and do not need to be removed as parasitic leaves during cultivation and management.