Having direct access to brain vasculature, astrocytes can take up available blood nutrients and metabolize them to fulfil their own energy needs and deliver metabolic intermediates to local synapses^1,2. These glial cells should be, therefore, metabolically adaptable to swap different substrates. However, in vitro and in vivo studies consistently show that astrocytes are primarily glycolytic^3–7, suggesting glucose is their main metabolic precursor. Notably, transcriptomic data^8,9 and in vitro¹⁰ studies reveal that mouse astrocytes are capable of mitochondrially oxidizing fatty acids and that they can detoxify excess neuronal-derived fatty acids in disease models^11,12. Still, the factual metabolic advantage of fatty acid use by astrocytes and its physiological impact on higher-order cerebral functions remain unknown. Here, we show that knockout of carnitine-palmitoyl transferase-1A (CPT1A)—a key enzyme of mitochondrial fatty acid oxidation—in adult mouse astrocytes causes cognitive impairment. Mechanistically, decreased fatty acid oxidation rewired astrocytic pyruvate metabolism to facilitate electron flux through a super-assembled mitochondrial respiratory chain, resulting in attenuation of reactive oxygen species formation. Thus, astrocytes naturally metabolize fatty acids to preserve the mitochondrial respiratory chain in an energetically inefficient disassembled conformation that secures signalling reactive oxygen species and sustains cognitive performance.

As ischemic stroke is associated with an excessive release of glutamate into the neuronal extracellular space, a decrease in blood glutamate levels could provide a mechanism to remove it from the brain tissue, by increasing the brain-blood gradient. In this regard, the ability of glutamate oxaloacetate transaminase (GOT) to metabolize glutamate in blood could represent a potential neuroprotective tool for ischemic stroke. This study aimed to determine the neuroprotective effects of GOT in an animal model of cerebral ischemia by means of a middle cerebral arterial occlusion (MCAO) following the Stroke Therapy Academic Industry Roundtable (STAIR) group guidelines. In this animal model, oxaloacetate-mediated GOT activation inhibited the increase of blood and cerebral glutamate after MCAO. This effect is reflected in a reduction of infarct size, smaller edema volume, and lower sensorimotor deficits with respect to controls. Magnetic resonance spectroscopy confirmed that the increase of glutamate levels in the brain parenchyma after MCAO is inhibited after oxaloacetate-mediated GOT activation. These findings show the capacity of the GOT to remove glutamate from the brain by means of blood glutamate degradation, and suggest the applicability of this enzyme as an efficient and novel neuroprotective tool against ischemic stroke.

Background and Purpose— Iron plays a detrimental role after experimental intracerebral hemorrhage (ICH). This study investigates whether high-serum ferritin levels are associated with poor outcome in patients with ICH. Methods— We studied 92 consecutive patients with primary hemispheric ICH within the first 12 hours from onset of symptoms (median, 3.3 hours). National Institute of Health Stroke Scale score, ICH, and peripheral edema volumes were measured at admission, 72 hours, and 7 days. Serum levels of ferritin and biomarkers of the inflammatory response were determined. The adjusted effect of ferritin on the full range of Rankin scale was analyzed by a general linear model. Results— Fifty-one patients (55.4%) had poor outcome (Rankin score >2). Older age, higher stroke severity, larger hematoma volume, intraventricular extension, mass effect, and higher IL-6 and ferritin levels at baseline (270.6 [SD 81.4] vs 74.6 [SD 43.4] ng/mL; P <0.001) were associated with poor outcome. The higher the ferritin quartile, the worse the Rankin score. For every ferritin quartile, the Rankin score increased by a mean of 1.4 points (95% CI, 1.04–1.69) after adjusting for prognostic variables. Ferritin levels remained stable for 72 hours and did not correlate with acute phase reactants. Conclusions— High-serum ferritin levels at admission are independently associated with poor outcome in patients with ICH. These findings may suggest a neurotoxic effect of increased body iron stores in patients with hemorrhagic stroke.

Brain ischaemia (stroke) triggers an intense inflammatory response predominately mediated by the accumulation of inflammatory cells and mediators in the ischaemic brain. In this context, regulatory T (Treg) cells, a subpopulation of CD4⁺ T cells with immunosuppressive and anti‐inflammatory properties, are activated in the late stages of the disease. To date, the potential therapeutic usefulness of Treg cells has not been tested. In this study, we aimed to investigate whether Treg cells exert protection/repair following stroke. Both the adoptive transfer of Treg cells into ischaemic rats and the stimulation of endogenous T‐cell proliferation using a CD28 superagonist reduced the infarct size at 3–28 days following the ischaemic insult. Moreover, T cell‐treated animals had higher levels of FoxP3 and lower levels of IL‐1β, CD11b+ and CD68+ cells in the infarcted hemisphere when compared with control animals. However, T‐cell treatment did not alter the rate of proliferation of NeuN‐, NCAM‐ or CD31‐positive cells, thereby ruling out neurogenesis and angiogenesis in protection. These results suggest that adoptive transfer of T cells is a promising therapeutic strategy against the neurological consequences of stroke.

The use of theranostics in neurosciences has been rare to date because of the limitations imposed on the free delivery of substances to the brain by the blood-brain barrier. Here we report the development of a theranostic system for the treatment of stroke, a leading cause of death and disability in developed countries. We first performed a series of proteomic, immunoblotting and immunohistological studies to characterize the expression of molecular biomarkers for the so-called peri-infarct tissue, a key region of the brain for stroke treatment. We confirmed that the HSP72 protein is a suitable biomarker for the peri-infarct region, as it is selectively expressed by at-risk tissue for up to 7 days following cerebral ischemia. We also describe the development of anti-HSP72 vectorized stealth immunoliposomes containing imaging probes to make them traceable by conventional imaging techniques (fluorescence and MRI) that were used to encapsulate a therapeutic agent (citicoline) for the treatment of cerebral ischemia. We tested the molecular recognition capabilities of these nano-platforms in vitro together with their diagnostic and therapeutic properties in vivo, in an animal model of cerebral ischemia. Using MRI, we found that 80% of vectorized liposomes were located on the periphery of the ischemic lesion, and animals treated with citicoline encapsulated on these liposomes presented lesion volumes up to 30% smaller than animals treated with free (non-encapsulated) drugs. Our results show the potential of nanotechnology for the development of effective tools for the treatment of neurological diseases.

Background and Purpose—: We aimed to evaluate the impact of brain atrophy on long-term clinical outcome in patients with acute ischemic stroke treated with endovascular therapy, and more specifically, to test whether there are interactions between the degree of atrophy and infarct volume, and between atrophy and age, in determining the risk of futile reperfusion. Methods—: We studied consecutive patients with acute ischemic stroke with proximal anterior circulation intracranial arterial occlusions treated with endovascular therapy achieving successful arterial recanalization. Brain atrophy was evaluated on baseline computed tomography with the global cortical atrophy scale, and Evans index was calculated to assess subcortical atrophy. Infarct volume was assessed on control computed tomography at 24 hours using the formula for irregular volumes (A×B×C/2). Main outcome variable was futile recanalization, defined by functional dependence (modified Rankin Scale score >2) at 3 months. The predefined interactions of atrophy with age and infarct volume were studied in regression models. Results—: From 361 consecutive patients with anterior circulation acute ischemic stroke treated with endovascular therapy, 295 met all inclusion criteria. Futile reperfusion was observed in 144 out of 295 (48.8%) patients. Cortical atrophy affecting parieto-occipital and temporal regions was associated with futile recanalization. Total global cortical atrophy score and Evans index were independently associated with futile recanalization in an adjusted logistic regression. Multivariable adjusted regression models disclosed significant interactions between global cortical atrophy score and infarct volume (odds ratio, 1.003 [95%CI, 1.002–1.004], P <0.001) and between global cortical atrophy score and age (odds ratio, 1.001 [95% CI, 1.001–1.002], P <0.001) in determining the risk of futile reperfusion. Conclusions—: A higher degree of cortical and subcortical brain atrophy is associated with futile endovascular reperfusion in anterior circulation acute ischemic stroke. The impact of brain atrophy on insufficient clinical recovery after endovascular reperfusion appears to be independently amplified by age and by infarct volume.