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Figure 2 | Particle and Fibre Toxicology

Figure 2

From: Cationic nanoparticles directly bind angiotensin-converting enzyme 2 and induce acute lung injury in mice

Figure 2

Down-regulated ACE2 expression in mice challenged with cationic PAMAM dendrimers. (A) Levels of AngII in the plasma of the vehicle- (control) and nanoparticle-treated (15 μg/g) mice at 3 hrs after administration. AngII levels were determined using radioimmunoassays. n = 4–5 mice per group. *p < 0.05 or **p < 0.01 for the comparison of the G4, G5-, and G6-treated groups with the vehicle (control) group (two-tailed t-test). (B) The ACE2 mRNA relative expression level of the vehicle- (control) and nanoparticle-treated (15 μg/g) mice at 3 hrs after administration. Data were normalized to the expression of β-actin reference gene. (two-tailed t-test). (C) Western blots of total lung samples obtained 3 hrs after the instillation of nanoparticles (15 μg/g). The blots are representative of three different mice for each treatment. Quantitative analyses of the ACE and ACE2 protein levels are illustrated. The levels are shown as the mean ACE- and ACE2-to-β-actin ratios ± SEM. n = 3 mice per treatment. **p < 0.01 for the comparison of the G5-, and G6-treated groups with the vehicle group (two-tailed t-test). (D) Binding of G5 and G5.5 nanoparticles to recombinant human ACE2 at different concentrations was measured by surface plasmon resonance (SPR). The detailed dynamic binding constant and equilibrium dissociation constant are shown in Table S2. (E) G5 and G5.5 nanoparticles at different concentrations were incubated with recombinant ACE2 and AngII. The levels of AngII in the enzymatic activity measurement system were determined by radioimmunoassay. n = 3 tests per group. (two-tailed t-tests). Data are shown as the mean values ± SEM. *p < 0.05 or **p < 0.01; N.S. means not significant.

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