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.

The Therapeutic Effect of Curcumin in Quinolinic Acid-Induced Neurotoxicity in Rats is Associated with BDNF, ERK1/2, Nrf2, and Antioxidant Enzymes.

In the present study we investigated the participation of brain-derived neurotropic factor (BDNF) on the activation of the mitogen activated protein kinase (MAPK) protein extracellular signal-regulated kinase-1/2 (ERK1/2) as a mechanism of curcumin (CUR) to provide an antioxidant defense system mediated by the nuclear factor erythroid 2-related factor 2 (Nrf2) in the neurotoxic model induced by quinolinic acid (QUIN). Wistar rats received CUR (400 mg/kg, intragastrically) for 6 days after intrastriatal injection with QUIN (240 nmol). CUR improved the motor deficit and morphological alterations induced by QUIN and restored BDNF, ERK1/2, and Nrf2 levels. CUR treatment avoided the decrease in the protein levels of glutathione peroxidase (GPx), glutathione reductase (GR), γ-glutamylcysteine ligase (γ-GCL), and glutathione (GSH) levels. Only, the QUIN-induced decrease in the GR activity was prevented by CUR treatment. Finally, QUIN increased superoxide dismutase 2 (SOD2) and catalase (CAT) levels, and the γGCL and CAT activities; however, this increase was major in the QUIN+CUR group for γ-GCL, CAT, and SOD activities. These data suggest that the therapeutic effect of CUR could involve BDNF action on the activation of ERK1/2 to induce increased levels of protein and enzyme activity of antioxidant proteins regulated by Nrf2 and GSH levels.

Sustained Activation of JNK Induced by Quinolinic Acid Alters the BDNF/TrkB Axis in the Rat Striatum.

Oxidative stress secondary to excitotoxicity is a common factor in the physiopathology of a variety of neurological disorders. In response to oxidative stress, several signaling pathways, such as MAPK, are activated or inactivated. Mitogen-activated protein kinase (MAPK) family activation must be finely regulated in time and intensity, as this pathway may either preserve cell survival or promote cell death. In the present study, the activation of MAPK in the excitotoxic injury induced by quinolinic acid (QUIN) was examined in vivo, at short and long times. We used different doses (30, 60, 120 and 240 nmol) of QUIN injected intrastriatally in the right rat striatum and the effect of this treatment on motor deficits, cellular damage, MAPK activation and BDNF/TrkB axis, were evaluated at 2 h and 7 days post-lesion. Higher doses of QUIN (120 and 240 nmol) induced rat motor deficits and caused morphological changes in neurons around the lesion core. QUIN decreased the activation of ERK1/2 in a dose-dependent manner at 7 days post-injection, and induced a sustained increase of c-Jun NH2-terminal kinase (JNK) activation from 2 h to 7 days post-injury. JNK activation was dependent on the QUIN-induced NMDAr activation (only 120 nmol). No significant difference in p38 activation with QUIN was observed. QUIN (120 and 240 nmol) decreased BDNF/TrkB levels at 7 days post-injury. JNK inhibition (by an intracerebroventricular injection of SP600125) prevented the QUIN-induced reduction in BDNF and TrkB at 7 day post-injury, suggesting a role for the QUIN-induced JNK activation on the observed decrease in BDNF levels.

Correction to: Chronic Administration of S-Allylcysteine Activates Nrf2 Factor and Enhances the Activity of Antioxidant Enzymes in the Striatum, Frontal Cortex and Hippocampus.

The original version of this article unfortunately contained a mistake.

Chronic Administration of S-Allylcysteine Activates Nrf2 Factor and Enhances the Activity of Antioxidant Enzymes in the Striatum, Frontal Cortex and Hippocampus.

Oxidative stress plays an important role in neurodegenerative diseases and aging. The cellular defense mechanisms to deal with oxidative damage involve the activation of transcription factor related to NF-E2 (Nrf2), which enhances the transcription of antioxidant and phase II enzyme genes. S-allylcysteine (SAC) is an antioxidant with neuroprotective properties, and the main organosulfur compound in aged garlic extract. The ability of SAC to activate the Nrf2 factor has been previously reported in hepatic cells; however this effect has not been studied in normal brain. In order to determine if the chronic administration of SAC is able to activate Nrf2 factor and enhance antioxidant defense in the brain, male Wistar rats were administered with SAC (25, 50, 100 and 200 mg/kg-body weight each 24 h, i.g.) for 90 days. The activation of Nrf2, the levels of p65 and 8-hydroxy-2-deoxyguanosine (8-OHdG) as well as the activities of the enzymes glutathione peroxidase (GPx), glutathione reductase (GR), catalase (CAT), superoxide dismutase (SOD), and glutathione S-transferase (GST) were evaluated in the hippocampus, striatum and frontal cortex. Results showed that SAC activated Nrf2 factor in the hippocampus (25-200 mg/kg) and striatum (100 mg/kg) and significantly decreased p65 levels in the frontal cortex (25-200 mg/kg). On the other hand, SAC increased GPx, GR, CAT and SOD activities mainly in the hippocampus and striatum, but it did not change GST activity. Finally, no changes were observed in 8-OHdG levels mediated by SAC in any brain region, but the hippocampus showed a major level of 8-OHdG compared with the striatum and frontal cortex. All these results suggest that in the hippocampus, the observed increase in the activity of antioxidant enzymes could be associated with the ability of SAC to activate Nrf2 factor; however, a different mechanism could be involved in the striatum and frontal cortex, since no changes were found in Nrf2 activation and p65 levels.