S100B Inhibitor Pentamidine Attenuates Reactive Gliosis and Reduces Neuronal Loss in a Mouse Model of Alzheimer's Disease - PubMed (original) (raw)

S100B Inhibitor Pentamidine Attenuates Reactive Gliosis and Reduces Neuronal Loss in a Mouse Model of Alzheimer's Disease

Carla Cirillo et al. Biomed Res Int. 2015.

Abstract

Among the different signaling molecules released during reactive gliosis occurring in Alzheimer's disease (AD), the astrocyte-derived S100B protein plays a key role in neuroinflammation, one of the hallmarks of the disease. The use of pharmacological tools targeting S100B may be crucial to embank its effects and some of the pathological features of AD. The antiprotozoal drug pentamidine is a good candidate since it directly blocks S100B activity by inhibiting its interaction with the tumor suppressor p53. We used a mouse model of amyloid beta- (Aβ-) induced AD, which is characterized by reactive gliosis and neuroinflammation in the brain, and we evaluated the effect of pentamidine on the main S100B-mediated events. Pentamidine caused the reduction of glial fibrillary acidic protein, S100B, and RAGE protein expression, which are signs of reactive gliosis, and induced p53 expression in astrocytes. Pentamidine also reduced the expression of proinflammatory mediators and markers, thus reducing neuroinflammation in AD brain. In parallel, we observed a significant neuroprotection exerted by pentamidine on CA1 pyramidal neurons. We demonstrated that pentamidine inhibits Aβ-induced gliosis and neuroinflammation in an animal model of AD, thus playing a role in slowing down the course of the disease.

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Figures

Figure 1

Figure 1

(a) Western blot and (b–f) densitometric analysis (arbitrary units normalized on the expression of the housekeeping protein β_-actin) showing the effect of 7 days of intrahippocampal injection of pentamidine (0.05–5 μ_g/mL/day) on GFAP (b), iNOS (c), p-p38 MAPK (d), COX-2 (e), and RAGE (f) expression in A_β_-injected mice. Results are expressed as mean ± SEM of n = 5 experiments performed in triplicate. ∗∗∗ P < 0.001 versus vehicle-treated mice; °_P < 0.05, °°_P < 0.01 and °°°P < 0.001 versus A_β_-treated mice.

Figure 2

Figure 2

(a) Electrophoretic mobility shift assay (EMSA) and the relative (b) densitometric analysis showing the effect following 7 days of intrahippocampal injection of pentamidine (0.05–5 μ_g/mL/day) on the expression of NF-κ_B in A_β_-injected mice. Results are expressed as mean ± SEM of n = 5 experiments performed in triplicate. ∗∗∗ P < 0.001 versus vehicle-treated mice; °°_P < 0.01 and °°°_P < 0.001 versus A_β_-treated mice.

Figure 3

Figure 3

Effect of pentamidine on release of nitrites (a), MDA (b), PGE2 (c), IL-1_β_ (d), and S100B (e) in hippocampal homogenates of A_β_-injected mice. Results are expressed as mean ± SEM of n = 5 experiments performed in triplicate. ∗∗∗ P < 0.001 versus vehicle-treated mice; °P < 0.05, °°P < 0.01 and °°°P < 0.001 versus A_β_-treated mice.

Figure 4

Figure 4

(a) Immunohistochemistry analysis showing the effect of pentamidine in hippocampal coronal sections after A_β_ injection. The upper panel shows GFAP-positive cells (astrocytes) infiltrating the hippocampi. Note the increased number of GFAP-positive cells in A_β_-treated (2) compared to vehicle-treated mice (1) and the dose-dependent reduction after pentamidine treatment (3-4-5). Scale bar: 200 μ_m. (b) Nissl staining showing the effect of pentamidine on pyramidal neuron loss in the CA1 area after A_β injection. Note the reduced number of neurons stained in A_β_-treated (2) compared to vehicle-treated mice (1) and the dose-dependent reduction of neuronal loss after pentamidine treatment (3-4-5). Scale bar: 200 μ_m. (c) Immunofluorescence analysis showing the effect of pentamidine in hippocampal coronal sections after A_β injection. Note the reduced number of neurons after A_β_ injection (2) compared to vehicle-treated mice (1) and the dose-dependent neuroprotection after pentamidine treatment (3-4-5). Scale bar: 200 μ_m. (d) Relative quantification of GFAP expression, (e) extent of CA1 damage measurement, and (f) number of neurons stained with Fluorojade B (FJB) in the hippocampi. Results are expressed as mean ± SEM of n = 5 experiments performed in triplicate. ∗∗∗ P < 0.001 versus vehicle-treated mice; °°_P < 0.01 and °°°P < 0.001 versus A_β_-treated mice.

Figure 5

Figure 5

Effect of pentamidine (0.05–5 μ_g/mL/day) on GFAP and p53 expression in astrocyte in the hippocampi of A_β_-injected mice. (a) Immunofluorescence analysis of hippocampal coronal sections. Note the increased GFAP expression in hippocampal astrocytes of A_β_-treated (2) compared to vehicle-treated mice (1) and the dose-dependent reduction after pentamidine treatment (3-4-5). Scale bar: 50 μ_m. (b) Relative quantification of p53-positive/GFAP-positive (open bars) and p53-positive/GFAP-positive (filled bars) astrocytes in the CA1 area of the brain. Results are expressed as mean ± SEM of n = 4 experiments performed in triplicate. ∗∗∗ P < 0.001 versus vehicle-treated mice; °_P < 0.05 and °°°_P < 0.001 versus A_β_-treated mice. §§ P < 0.01 versus vehicle-treated mice; ## P < 0.01, ### P < 0.001 versus A_β_-treated mice.

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