Longitudinal evaluation of neuroinflammation and oxidative stress in a mouse model of Alzheimer disease using positron emission tomography.

BACKGROUND: Validation of new biomarkers of Alzheimer disease (AD) is crucial for the successful development and implementation of treatment strategies. Additional to traditional AT(N) biomarkers, neuroinflammation biomarkers, such as translocator protein (TSPO) and cystine/glutamine antiporter system (xc-), could be considered when assessing AD progression. Herein, we report the longitudinal investigation of [18F]DPA-714 and [18F]FSPG for their ability to detect TSPO and xc- biomarkers, respectively, in the 5xFAD mouse model for AD. METHODS: Expression of TSPO and xc- system was assessed longitudinally (2-12 months of age) on 5xFAD mice and their respective controls by positron emission tomography (PET) imaging using radioligands [18F]DPA-714 and [18F]FSPG. In parallel, in the same mice, amyloid-ß plaque deposition was assessed with the amyloid PET radiotracer [18F]florbetaben. In vivo findings were correlated to ex vivo immunofluorescence staining of TSPO and xc- in microglia/macrophages and astrocytes on brain slices. Physiological changes of the brain tissue were assessed by magnetic resonance imaging (MRI) in 12-month-old mice. RESULTS: PET studies showed a significant increase in the uptake of [18F]DPA-714 and [18F]FSPG in the cortex, hippocampus, and thalamus in 5xFAD but not in WT mice over time. The results correlate with Aß plaque deposition. Ex vivo staining confirmed higher TSPO overexpression in both, microglia/macrophages and astrocytes, and overexpression of xc- in non-glial cells of 5xFAD mice. Additionally, the results show that Aß plaques were surrounded by microglia/macrophages overexpressing TSPO. MRI studies showed significant tissue shrinkage and microstructural alterations in 5xFAD mice compared to controls. CONCLUSIONS: TSPO and xc- overexpression can be assessed by [18F]DPA-714 and [18F]FSPG, respectively, and correlate with the level of Aß plaque deposition obtained with a PET amyloid tracer. These results position the two tracers as promising imaging tools for the evaluation of disease progression. Longitudinal in vivo study in the 5xFAD mouse model shows that TSPO and oxidative stress assessment through [18F]DPA-714 and [18F]FSPG-PET imaging, respectively, could serve as a potential tool for the evaluation of Alzheimer disease progression.

Alkynyl Gold(I) complexes derived from 3-hydroxyflavones as multi-targeted drugs against colon cancer.

The design of multi-targeted drugs has gained considerable interest in the last decade thanks to their advantages in the treatment of different diseases, including cancer. The simultaneous inhibition of selected targets from cancerous cells to induce their death represents an attractive objective for the medicinal chemist in order to enhance the efficiency of chemotherapy. In the present work, several alkynyl gold(I) phosphane complexes derived from 3-hydroxyflavones active against three human cancer cell lines, colorectal adenocarcinoma Caco-2/TC7, breast adenocarcinoma MCF-7 and hepatocellular carcinoma HepG2, have been synthesized and characterized. Moreover, these compounds display high selective index values towards differentiated Caco-2 cells, which are considered as a model of non-cancerous cells. The antiproliferative effect of the most active complexes [Au(L2b)PPh3] (3b) and [Au(L2c)PTA] (4c) on Caco-2 cells, seems to be mediated by the inhibition of the enzyme cyclooxygenase-1/2 and alteration of the activities of the redox enzymes thioredoxin reductase and glutathione reductase. Both complexes triggered cell death by apoptosis, alterations in cell cycle progression and increased of ROS production. These results provide support for the suggestion that multi-targeting approach involving the interaction with cyclooxygenase-1/2 and the redox enzymes that increases ROS production, enhances cell death in vitro. All these results indicate that complexes [Au(L2b)PPh3] and [Au(L2c)PTA] are promising antiproliferative agents for further anticancer drug development.