Universite de la Reunion

It is well recognized that type II Diabetes (T2D) and overweight/obesity are established risk factors for stroke, worsening also their consequences. However, the underlying mechanisms by which these disorders aggravate outcomes are not yet clear limiting the therapeutic opportunities. To fill this gap, we characterized, for the first time, the effects of T2D and obesity on the brain repair mechanisms occurring 7 days after stroke, notably glial scarring. In the present study, by performing a 30-minute middle cerebral artery occlusion (MCAO) on db/db (obese diabetics mice) and db/+ (controls) mice, we demonstrated that obese and diabetic mice displayed larger lesions (i.e. increased infarct volume, ischemic core, apoptotic cell number) and worsened neurological outcomes compared to their control littermates. We then investigated the formation of the glial scar in control and db/db mice 7 days post-stroke. Our observations argue in favor of a stronger and more persistent activation of astrocytes and microglia in db/db mice. Furthermore, an increased deposition of extracellular matrix (ECM) was observed in db/db vs control mice (i.e. chondroitin sulfate proteoglycan and collagen type IV). Consequently, we demonstrated for the first time that the db/db status is associated with increased astrocytic and microglial activation 7 days after stroke and resulted in higher deposition of ECM within the damaged area. Interestingly, the injury-induced neurogenesis appeared stronger in db/db as shown by the labeling of migrating neuroblast. This increase appeared correlated to the larger size of lesion. It nevertheless raises the question of the functional integration of the new neurons in db/db mice given the observed dense ECM, known to be repulsive for neuronal migration. Carefully limiting glial scar formation after stroke represents a promising area of research for reducing neuronal loss and limiting disability in diabetic/obese patients.

High-density lipoproteins (HDLs) are known for their cardiovascular protection due to apolipoprotein A-1 (ApoA1), their primary protein. ApoA1 promotes cholesterol reverse transport and exhibits antioxidant and anti-inflammatory properties. Although increasing HDL levels has not consistently reduced cardiovascular mortality in clinical trials, reconstituted HDL (rHDL) nanoparticles containing ApoA1 show potential in treating acute inflammation, such as in ischemic stroke, sepsis, and even COVID-19. ApoA1 is commonly produced in bacteria due to its simplicity and potential therapeutic optimisation. Addition of a histidine tag to recombinant ApoA1 may improve purification, stability and therapeutic efficacy, although its functional impact remains a subject of debate. In this study, ApoA1 with a poly-histidine tag (His-rApoA1) was produced in a clear coli system for simplified purification, followed by an evaluation of the tag's effects on rHDL nanoparticle properties. rHDL and His-rHDL nanoparticles were prepared using the sodium cholate dialysis method, combining recombinant rApoA1 or His-rApoA1 with phosphatidylcholine at a 1:75 M ratio. Nuclear magnetic resonance confirmed that both forms of rApoA1 structurally resembled plasma ApoA1, whether lipid-free or in nanoparticle form. Dynamic light scattering and electron microscopy revealed nanoparticle sizes around 7 nm with native HDL-like morphology. Testing on endothelial cells (EA.hy926) showed rapid uptake of rHDL and His-rHDL while preserving cell viability. Additionally, both nanoparticles reduced interleukin-6 and ICAM-1 expression in cells, demonstrating their anti-inflammatory and protective effects, unaffected by the poly-histidine tag. Intravenous injection in mice shows homogeneous distribution of His-rHDL in the liver, lungs, and spleen, with no cytotoxicity, indicating potential use for treating inflammatory diseases.

The market for olive leaf dietary supplements is expanding rapidly and is valued at $437.15 million today. However, information on the control of these products is sketchy and the origin and variety of olives are rarely stated. The aim of this research was to validate a simple and rapid screening method for oleuropein determination in olive leaf dietary supplements. A matrix blank was prepared by removal of oleuropein from a mixture of dietary supplements and the matrix was then spiked with known concentrations to create a spiked matrix calibration curve in the range 5 - 40% oleuropein. Five replicate extractions and analyses of the matrix standards were carried out over 10 days. Precision was less than 6% RSD and linearity was demonstrated by the Fischer test. Extraction recovery was > 90% and there was a strong linear relationship between authentic and matrix standards. All tested products conformed to the label claim which was strongly correlated with total polyphenols measured by the Folin-Ciocalteau method. Antioxidant activity was measured by the DPPH assay and was found to be strongly correlated with total phenol content and oleuropein concentration.