Impact of hydroxytyrosol on stroke: tracking therapy response on neuroinflammation and cerebrovascular parameters using PET-MR imaging and on functional outcomes

• Published in: Theranostics 2021-01, Vol.11 (9), p.4030-4049
• Main Authors: Barca, Cristina, Wiesmann, Maximilian, Calahorra, Jesús, Wachsmuth, Lydia, Döring, Christian, Foray, Claudia, Heiradi, Ali, Hermann, Sven, Peinado, Maria Ángeles, Siles, Eva, Faber, Cornelius, Schäfers, Michael, Kiliaan, Amanda J, Jacobs, Andreas H, Zinnhardt, Bastian
• Format: Article
• Language: English
• Subjects: Antioxidants; Carotid arteries; Experiments; Fentanyl; Free radicals; Inflammation; Ischemia; Laboratory animals; Nitric oxide; Oxidative stress; Research Paper; Stroke; Tumor necrosis factor-TNF; Veins & arteries
• ISSN: 1838-7640; 1838-7640
• DOI: 10.7150/thno.48110

Immune cells have been implicated in influencing stroke outcomes depending on their temporal dynamics, number, and spatial distribution after ischemia. Depending on their activation status, immune cells can have detrimental and beneficial properties on tissue outcome after stroke, highlighting the need to modulate inflammation towards beneficial and restorative immune responses. Novel dietary therapies may promote modulation of pro- and anti-inflammatory immune cell functions. Among the dietary interventions inspired by the Mediterranean diet, hydroxytyrosol (HT), the main phenolic component of the extra virgin olive oil (EVOO), has been suggested to have antioxidant and anti-inflammatory properties . However, immunomodulatory effects of HT have not yet been studied after stroke. The aim of this project is therefore to monitor the therapeutic effect of a HT-enriched diet in an experimental stroke model using non-invasive multimodal imaging, behavioural phenotyping and cross-correlation with parameters. A total of N = 22 male C57BL/6 mice were fed with either a standard chow (n = 11) or a HT enriched diet (n = 11) for 35 days, following a 30 min transient middle cerebral artery occlusion (tMCAo). T -weighted (lesion) and perfusion (cerebral blood flow)-/diffusion (cellular density)-weighted MR images were acquired at days 1, 3, 7, 14, 21 and 30 post ischemia. [ F]DPA-714 (TSPO, neuroinflammation marker) PET-CT scans were acquired at days 7, 14, 21 and 30 post ischemia. Infarct volume (mm ), cerebral blood flow (mL/100g/min), apparent diffusion coefficient (10 ·mm /s) and percentage of injected tracer dose (%ID/mL) were assessed. Behavioural tests (grip test, rotarod, open field, pole test) were performed prior and after ischemia to access therapy effects on sensorimotor functions. analyses (IHC, IF, WB) were performed to quantify TSPO expression, immune cells including microglia/macrophages (Iba-1, F4/80), astrocytes (GFAP) and peripheral markers in serum such as thiobarbituric acid reactive substances (TBARS) and nitric oxide (NO) 35 days post ischemia. Additionally, gene expression of pro- and anti-inflammatory markers were assessed by rt-qPCR, including , , , and . No treatment effect was observed on temporal [ F]DPA-714 uptake within the ischemic and contralateral region (two-way RM ANOVA, = 0.71). Quantification of the percentage of TSPO area by immunoreactivity indicated a slight 2-fold increase in TSPO expression within the infarct region in HT-fed m