Fig 2: Schematic representation of the NVU at the level of brain capillary. (A) Endothelial cells (ECs) line the capillary lumen. They are connected via transmembrane tight junction proteins. Intercellular junctions provide tight adhesion and facilitate communication between ECs. The endothelium is separated from other cells by basal lamina (basement membrane). Astrocyte end-feet encase the vessel wall. Resting microglia with ramified phenotype survey the environment. (B) A model of AD-associated BBB dysfunction. Aß deposits in the ECs that lose tight junction proteins and detach. Basal lamina disorganizes, thickens, and splits. Pericytes degenerate. Astroglia degenerate, reduce the levels of GFAP, number of extending processes, and retract their end-feet. Recruited perivascular macrophages and microglia display an activated phenotype. These alterations contribute to the diminishing of Aß clearance, leakage of plasma proteins, and neuroinflammation.

Fig 3: Representative hippocampal bright-field × 40 micrographs from 3×Tg-AD control (A) and L-norvaline treated (B) mice brain (scale bar = 100 µm) with insets showing penetrating microvessels at × 100 magnification (scale bar = 10 µm). Quantification of GFAP+ stain intensity (C), astrocyte cell volume (D), and the number of processes per astrocyte (E), examined with Imaris® and analyzed via Student’s unpaired t-test (n = 18 for control and n = 19 for treated mice), ns: not significant, ** p < 0.01.

Fig 4: Hippocampal FAK overexpression significantly reduces astrogliosis, but not microgliosis. (A,B) Representative 20× brightfield images of hippocampi CA1 regions from control and FAK-OE mice labeled with anti-GFAP for astrocytes. Insets: Representative astrocytes, left: Respective trace drawings of representative astrocytes shown in insets. Scale bar, 50 µm (insets: 5 µm). (C) Quantification of astrocyte cell density in hippocampi of control and FAK-OE mice. *** p < 0.001 by unpaired Student’s t-test. (D) Quantification of astrocyte surface area *** p < 0.001 by unpaired Student’s t-test. (E) Quantification of Sholl interactions between astrocyte processes in 15, 24, and 33 µm radius from cell center. p = N.S., ** p = 0.0092 by an unpaired Student’s t-test. (F,G) Representative 2020× brightfield images of hippocampi CA1 regions from control and FAK-OE mice labeled with anti-Iba1 for microglia. Insets: Representative microglia, left: Respective trace drawings of representative microglia shown in insets. Scale bar, 50 µm (insets: 5 µm). (H) Quantification of microglia cell density in hippocampi of control and FAK-OE mice. p = N.S. by an unpaired Student’s t-test. (I) Quantification of microglia surface area. p = N.S. by an unpaired Student’s t-test. N = 40 fields from three mice in each group.

Fig 5: The GluA4 AMPAR subunit is reduced in adult spinal cord oligodendrocytes from PLPcreER+;GluA4fl/fl compared to PLPcreER-;GluA4fl/fl mice.Mice were tamoxifen-induced at 6 weeks of age and euthanized for immunofluorescence staining at 8 weeks of age. Representative confocal images of PLPcreER-;GluA4fl/fl (WT) versus PLPcreER+;GluA4fl/fl (KO) mouse lumbar spinal cords. (A) Images taken in lateral funiculus white matter. Far-red (pseudocolored magenta) immunofluorescence represents anti-GluA4 (first column). Green immunofluorescence represents the mature oligodendrocyte marker anti-CC1 (second column). Blue fluorescence represents the nuclear marker bisbenzimide (third column). All images are merged in the final column (Merge). (B) Images taken in lateral funiculus white matter. Far-red (pseudocolored magenta) immunofluorescence represents anti-GluA4 (first column). Green immunofluorescence represents the astrocyte marker anti-GFAP (second column). All images are merged in the final column (Merge). (C) Images taken in ventral gray matter. Far-red (pseudocolored magenta) immunofluorescence represents anti-GluA4 (first column). Green immunofluorescence represents the neuronal marker NeuN (second column). Blue fluorescence represents the nuclear marker bisbenzimide (third column). All images are merged in the final column (Merge). Images are representative of n = 4 mice per genotype. Scale bars, 10 µm.