Extracellular vesicles from neural progenitor cells promote functional recovery after stroke in mice with pharmacological inhibition of neurogenesis

Neural progenitor cells (NPCs) of the subventricular zone proliferate in response to ischemic stroke in the adult mouse brain. Newly generated cells have been considered to influence recovery following a stroke. However, the mechanism underlying such protection is a matter of active study since it has been thought that proliferating NPCs mediate their protective effects by secreting soluble factors that promote recovery rather than neuronal replacement in the ischemic penumbra. We tested the hypothesis that this mechanism is mediated by the secretion of multimolecular complexes in extracellular vesicles (EVs). We found that the molecular influence of oxygen and glucose-deprived (OGD) NPCs-derived EVs is very limited in improving overt neurological alterations caused by stroke compared to our recently reported astrocyte-derived EVs. However, when we inhibited the ischemia-triggered proliferation of NPCs with the chronic administration of the DNA synthesis inhibitor Ara-C, the effect of NPC-derived EVs became evident, suggesting that the endogenous protection exerted by the proliferation of NPC is mainly carried out through a mechanism that involves the intercellular communication mediated by EVs. We analyzed the proteomic content of NPC-derived EVs cargo with label-free relative abundance mass spectrometry and identified several molecular mediators of neuronal recovery within these vesicles. Our findings indicate that NPC-derived EVs are protective against the ischemic cascade activated by stroke and, thus, hold significant therapeutic potential.

Experimental Pulmonary Tuberculosis in the Absence of Detectable Brain Infection Induces Neuroinflammation and Behavioural Abnormalities in Male BALB/c Mice

Tuberculosis (TB) is a chronic infectious disease in which prolonged, non-resolutive inflammation of the lung may lead to metabolic and neuroendocrine dysfunction. Previous studies have reported that individuals coursing pulmonary TB experience cognitive or behavioural changes; however, the pathogenic substrate of such manifestations have remained unknown. Here, using a mouse model of progressive pulmonary TB, we report that, even in the absence of brain infection, TB is associated with marked increased synthesis of both inflammatory and anti-inflammatory cytokines in discrete brain areas such as the hypothalamus, the hippocampal formation and cerebellum accompanied by substantial changes in the synthesis of neurotransmitters. Moreover, histopathological findings of neurodegeneration and neuronal death were found as infection progressed with activation of p38, JNK and reduction in the BDNF levels. Finally, we perform behavioural analysis in infected mice throughout the infection, and our data show that the cytokine and neurochemical changes were associated with a marked onset of cognitive impairment as well as depressive- and anxiety-like behaviour. Altogether, our results suggest that besides pulmonary damage, TB is accompanied by an extensive neuroinflammatory and neurodegenerative state which explains some of the behavioural abnormalities found in TB patients.

Sulforaphane reduces the alterations induced by quinolinic acid: modulation of glutathione levels

Glutamate-induced excitotoxicity involves a state of acute oxidative stress, which is a crucial event during neuronal degeneration and is part of the physiopathology of neurodegenerative diseases. In this work, we evaluated the ability of sulforaphane (SULF), a natural dietary isothiocyanate, to induce the activation of transcription factor Nrf2 (a master regulator of redox state in the cell) in a model of striatal degeneration in rats infused with quinolinic acid (QUIN). Male Wistar rats received SULF (5mg/kg, i.p.) 24h and 5min before the intrastriatal infusion of QUIN. SULF increased the reduced glutathione (GSH) levels 4h after QUIN infusion, which was associated with its ability to increase the activity of glutathione reductase (GR), an antioxidant enzyme capable to regenerate GSH levels at 24h. Moreover, SULF treatment increased glutathione peroxidase (GPx) activity, while no changes were observed in γ-glutamyl cysteine ligase (GCL) activity. SULF treatment also prevented QUIN-induced oxidative stress (measured by oxidized proteins levels), the histological damage and the circling behavior. These results suggest that the protective effect of SULF could be related to its ability to preserve GSH levels and increase GPx and GR activities.