The adhesion and migration of microglia to β-amyloid (Aβ) is decreased with aging and inhibited by Nogo/NgR pathway

Abstract Background Alzheimer’s disease is characterized by progressive accumulation of β-amyloid (Aβ)-containing amyloid plaques, and microglia play a critical role in internalization and degradation of Aβ. Our previous research confirmed that Nogo-66 binding to Nogo receptors (NgR) expressed on microglia inhibits cell adhesion and migration in vitro. Methods The adhesion and migration of microglia isolated from WT and APP/PS1 mice from different ages were measured by adhesion assays and transwells. After NEP1-40 (a competitive antagonist of Nogo/NgR pathway) was intracerebroventricularly administered via mini-osmotic pumps for 2 months in APP/PS1 transgenic mice, microglial recruitment toward Aβ deposits and CD36 expression were determined. Results In this paper, we found that aging led to a reduction of microglia adhesion and migration to fAβ1–42 in WT and APP/PS1 mice. The adhesion and migration of microglia to fAβ1–42 were downregulated by the Nogo, which was mediated by NgR, and the increased inhibitory effects of the Nogo could be observed in aged mice. Moreover, Rho GTPases contributed to the effects of the Nogo on adhesion and migration of microglia to fAβ1–42 by regulating cytoskeleton arrangement. Furthermore, blocking the Nogo/NgR pathway enhanced recruitment of microglia toward Aβ deposits and expression of CD36 in APP/PS1 mice. Conclusion Taken together, Nogo/NgR pathway could take part in Aβ pathology in AD by modulating microglial adhesion and migration to Aβ and the Nogo/NgR pathway might be an important target for treating AD

Additional file 1 of Early application of metagenomics next-generation sequencing may significantly reduce unnecessary consumption of antibiotics in patients with fever of unknown origin

Supplementary Material

Additional file 2: Figure S2. of The blockage of the Nogo/NgR signal pathway in microglia alleviates the formation of Aβ plaques and tau phosphorylation in APP/PS1 transgenic mice

The levels of secreted Aβ40 and Aβ42 in BV-2 microglia-conditioned medium. Before added to the protein-coated wells, BV-2 microglia was transfected with Ctrl siRNA or NgR siRNA to suppress the expression of NgR. The cells were then exposed to PBS or Nogo-P4 for 6 h. And then, the conditioned medium was collected and centrifuged to discard cell debris. The release of Aβ40 (Figure A) and Aβ42 (Figure B) in the conditioned medium was determined using ELISA. Values were reported as mean ± SD. n = 3. (PDF 95 kb

Additional file 1: Figure S1. of The blockage of the Nogo/NgR signal pathway in microglia alleviates the formation of Aβ plaques and tau phosphorylation in APP/PS1 transgenic mice

The efficiency of the knockdown with NgR siRNA and the cellular ability of BV-2 microglial cells. (A and B) The expression of NgR on BV-2 microglia was determined by western blot after transfected with NgR siRNA or control siRNA. (C) After BV-2 microglia treatment with NgR siRNA or control siRNA, the survival rate of microglia was determined by MTT assay. Values were reported as mean ± SD, as a percentage of values determined in PBS group (control, 100 %). *p < 0.05; **p < 0.01; ***p < 0.001, when compared with PBS, n = 3. (PDF 11 kb

Additional file 2: of The adhesion and migration of microglia to β-amyloid (Aβ) is decreased with aging and inhibited by Nogo/NgR pathway

Figure S2. The locally proliferated microglia. (A) The locally proliferated microglia were quantified using IF staining of Ki67. (B) The ratio of Ki67+ cells/total cells (in %). Values were reported as mean ± SD. (PDF 458 kb

Additional file 1: of The adhesion and migration of microglia to β-amyloid (Aβ) is decreased with aging and inhibited by Nogo/NgR pathway

Figure S1. Congo Red dye binding assay of fAβ1–42. The aggregation of fAβ1–42 was validated by the Congo Red dye binding assay. (A) The relative Cb of fAβ1–42. (B) Photomicrographs of fAβ1–42. *p < 0.05; **p < 0.01, when compared with 0 μM fAβ1–42, n = 3. (PDF 120 kb

Additional file 4: of The adhesion and migration of microglia to β-amyloid (Aβ) is decreased with aging and inhibited by Nogo/NgR pathway

Figure S4. The recruit of 12F4+ Aβ to microglia in APP/PS1 mice. Mice brain sections were processed for anti-12F4 and anti-Iba1 immunofluorescence as indicated. Bar = 50 μM. B: Ten randomly chosen plaque areas in the cortex and hippocampus were evaluated for Iba1/12F4+ Aβ colocalization per animal. Values were reported as the mean ± SD, as a percentage of values determined in vehicle group (control, 100%). ***p < 0.01, when compared with the vehicle group, n = 3–6. (PDF 71 kb