Faculdade de Ciencias e Tecnologia

Background: Remote ischemic conditioning (RIC) is a procedure applied in a limb for triggering endogenous protective pathways in distant organs, namely brain or heart. The underlying mechanisms of RIC are still not fully understood, and it is hypothesized they are mediated either by humoral factors, immune cells and/or the autonomic nervous system. Herein, heart rate variability (HRV) was used to evaluate the electrophysiological processes occurring in the heart during RIC and, in turn to assess the role of autonomic nervous system. Methods: Healthy subjects were submitted to RIC protocol and electrocardiography (ECG) was used to evaluate HRV, by assessing the variability of time intervals between two consecutive heart beats. This is a pilot study based on the analysis of 18 ECG from healthy subjects submitted to RIC. HRV was characterized in three domains (time, frequency and non-linear features) that can be correlated with the autonomic nervous system function.

One sentence summary: For the first time in yeast model, it was demonstrated that low concentrations of carbon monoxide prevent oxidative stress-induced cell death in an autophagy-dependent manner. Editor: Cristina Mazzoni † Cí audia Figueiredo-Pereira and Regina Menezes contributed equally to this work. ‡ Helena L. A. Vieira, http://orcid.org/0000 ABSTRACT Autophagy is an autodigestive process, promoting cytoprotection by the elimination of dysfunctional organelles, misfolded proteins and toxic aggregates. Carbon monoxide (CO) is an endogenous gasotransmitter that under low concentrations prevents cell death and inflammation. For the first time, the role of autophagy in CO-mediated cytoprotection against oxidative stress was evaluated in the model yeast Saccharomyces cerevisiae. The boron-based CO-releasing molecule, CORM-A1, was used to deliver CO. CORM-A1 partially prevented oxidative stress-induced cell death in yeast. Likewise, CORM-A1 activated autophagy under basal physiological conditions, which were assessed by autophagic flux and the expression of mCherry-Atg8 or GFP-Atg8. Inhibition of autophagy by knocking out key autophagic genes in yeast (ATG8 or ATG11) blocked CORM-A1 cytoprotective effect, indicating the critical role of autophagy in CO-induced cytoprotection. The CO-mediated cytoprotection via autophagy induction observed in yeast was validated in primary cultures of astrocytes, a well-characterized model for CO's cytoprotective functions. As in yeast, CORM-A1 prevented oxidative stress-induced cell death in an autophagy-dependent manner in astrocytes. Overall, our data support the cytoprotective action of CO against oxidative stress. CO promotes cytoprotection in yeast via autophagy, opening new possibilities for the study of molecular mechanisms of CO's biological functions using this powerful eukaryotic model.

Berries contain bioactive polyphenols, whose capacity to prevent cardiovascular diseases has been established recently in animal models as well in human clinical trials. However, cellular processes and molecular targets of berries polyphenols remain to be identified. The capacity of a polyphenol-enriched diet (i.e., blueberries, blackberries, raspberries, strawberry tree fruits and Portuguese crowberries berries mixture) to promote animal survival and protect cardiovascular function from salt-induced hypertension was evaluated in a chronic salt-sensitive Dahl rat model. The daily consumption of berries improved survival of Dahl/ salt-sensitive rats submitted to high-salt diet and normalized their body weight, renal function and blood pressure. In addition, a prophylactic effect was observed at the level of cardiac hypertrophy and dysfunction, tissue cohesion and cardiomyocyte hypertrophy. Berries also protected the aorta from fibrosis and modulated the expression of aquaporin-1, a channel involved in endothelial water and nitric oxide permeability. Left ventricle proteomics analysis led to the identification of berries and salt metabolites targets, including cystein and glycin-rich protein 3 (CSRP3), a protein involved in myocyte cytoarchitecture. In neonatal rat ventricular cardiomyocytes, CSRP3 was validated as a target of a berries-derived polyphenol metabolite, 4-methylcatechol sulfate, at micromolar concentrations, mimicking physiological conditions of human plasma circulation. Accordingly, siRNA silencing of CSRP3 and 4-methylcatechol sulfate pretreatment reversed cardiomyocyte hypertrophy and CSRP3 overexpression induced by phenylephrine. Our systemic study clearly supports the modulation of CSRP3 by a polyphenol-rich berries diet as an efficient cardioprotective strategy in hypertension-induced heart failure.

Carbon monoxide (CO) is an endogenous gasotransmitter that limits inflammation and prevents apoptosis in several tissues, including the brain. Low concentrations of CO are cytoprotective in astrocytes, neurons, and microglia, but the underlying molecular mechanisms remain poorly understood. This work aims at identification of alterations in gene expression conferred by CO in primary cultures of cortical astrocytes, for further disclosure of the molecular mechanism of action of the gasotransmitter. Astrocytes were treated with the CO-releasing molecule CORM-A1 for 40 min, and transcriptional changes were analyzed using RNASeq. A total of 162 genes were differentially expressed in response to CO treatment, and 7 of these genes were selected for further analysis: FosB, Scand1, Rgs10, Actg1, Panx1, Pcbdh21, and Rn18s. The alterations in their expression were further validated using qRT-PCR. An increase in FosB protein expression was also observed after 40 min of CORM-A1 treatment, as determined by a western blot. CO-induced FosB expression and cytoprotection were both abrogated in the presence of the P2X7 receptor antagonist A-438079. Furthermore, CORM-A1 increased phosphorylation of calcium/ calmodulin-dependent protein kinase II (CaMKII), which is a downstream event of P2X7R activation. The functional importance of FosB in CO-induced survival was assessed by knocking down its expression with FosB siRNA. Astrocytes were challenged to death with oxidative stress and cell viability was assessed 24 h later. Downregulation of FosB did not prevent the effects of CO in the inhibition of astrocytic cell death. Nevertheless, the transcriptomic changes observed upon treatment of astrocytes with CO open new opportunities for further studies on CO cytoprotective pathways.

Over the last decades, the silent-killer carbon monoxide (CO) has been shown to also be an endogenous cytoprotective molecule able to inhibit cell death and modulate mitochondrial metabolism. Neuronal metabolism is mostly oxidative and neurons also use glucose for maintaining their anti-oxidant status by generation of reduced glutathione (GSH) via the pentose-phosphate pathway (PPP). It is established that neuronal differentiation depends on reactive oxygen species (ROS) generation and signalling, however there is a lack of information about modulation of the PPP during adult neurogenesis. Thus, the main goal of this study was to unravel the role of CO on cell metabolism during neuronal differentiation, particularly by targeting PPP flux and GSH levels as anti-oxidant system. A human neuroblastoma SH-S5Y5 cell line was used, which differentiates into post-mitotic neurons by treatment with retinoic acid (RA), supplemented or not with CO-releasing molecule-A1 (CORM-A1). SH-SY5Y cell differentiation supplemented with CORM-A1 prompted an increase in neuronal yield production. It did, however, not alter glycolytic metabolism, but increased the PPP. In fact, CORM-A1 treatment stimulated (i) mRNA expression of 6-phosphogluco-nate dehydrogenase (PGDH) and transketolase (TKT), which are enzymes for oxidative and non-oxidative phases of the PPP, respectively and (ii) protein expression and activity of glucose 6-phosphate dehydrogenase (G6PD) the rate-limiting enzyme of the PPP. Likewise, whenever G6PD was knocked-down CO-induced improvement on neuronal differentiation was reverted, while pharmacological inhibition of GSH synthesis did not change CO's effect on the improvement of neuronal differentiation. Both results indicate the key role of PPP in CO-modulation of neuronal differentiation. Furthermore, at the end of SH-SY5Y neuronal differentiation process, CORM-A1 supplementation increased the ratio of reduced and oxidized glutathione (GSH/GSSG) without alteration of GSH metabolism. These data corroborate with PPP stimulation. In conclusion, CO improves neuronal differentiation of SH-S5Y5 cells by stimulating the PPP and modulating the GSH system.

Polyphenols are natural compounds present in fruits and vegetables that can exert beneficial effects on human health and notably, on the cardiovascular system. Some of these compounds showed significant protective activities toward atherosclerosis, hypertension, myocardial infarction, anthracyclin-induced cardiomyopathy, angiogenesis as well as heart failure. Polyphenols can act through systemic effects as well as through modulation of signaling pathways such as redox signaling, inflammation, autophagy and cell death in the heart and vessels. These effects can be mediated by changes in expression level and by post-translational modifications of proteins (e.g. Stat1, CaMKII, Sirtuins, BCL-2 family members, PDEs, TRF2, eNOS and SOD). This non-comprehensive short review aims to summarize recent knowledge on the main pharmacological effects and mechanisms of cardioprotection of pure polyphenols, using different approaches such as cell culture, animal models and human studies. Copyright© Bentham Science Publishers; For any queries, please email at epub@benthamscience.org. Format: Abstract 1,2 1,2 3 4 5 4 3

Exploratory studies using human fetal tissue have suggested that intrastriatal transplanta-tion of dopaminergic neurons may become a future treatment for patients with Parkinson's disease. However, the use of human fetal tissue is compromised by ethical, regulatory and practical concerns. Human stem cells constitute an alternative source of cells for transplan-tation in Parkinson's disease, but efficient protocols for controlled dopaminergic differentiation need to be developed. Short-term, low-level carbon monoxide (CO) exposure has been shown to affect signaling in several tissues, resulting in both protection and generation of reactive oxygen species. The present study investigated the effect of CO produced by a novel CO-releasing molecule on dopaminergic differentiation of human neural stem cells. Short-term exposure to 25 ppm CO at days 0 and 4 significantly increased the relative content of β-tubulin III-immunoreactive immature neurons and tyrosine hydroxylase expressing catecholaminergic neurons, as assessed 6 days after differentiation. Also the number of microtubule associated protein 2-positive mature neurons had increased significantly. Moreover , the content of apoptotic cells (Caspase3) was reduced, whereas the expression of a cell proliferation marker (Ki67) was left unchanged. Increased expression of hypoxia induc-ible factor-1α and production of reactive oxygen species (ROS) in cultures exposed to CO may suggest a mechanism involving mitochondrial alterations and generation of ROS. In conclusion, the present procedure using controlled, short-term CO exposure allows efficient dopaminergic differentiation of human neural stem cells at low cost and may as such be PLOS ONE | https://doi.org/10.1371/journal.pone.

Microglia fulfill important immunological functions in the brain by responding to pathological stresses and modulating their activities according to pro-or anti-inflammatory stimuli. Recent evidence indicates that changes in metabolism accompany the switch in microglia activation state, favoring glycolysis over oxidative phosphorylation when cells exhibit a pro-inflammatory phenotype. Carbon monoxide (CO), a byproduct of heme breakdown by heme oxygenase, exerts anti-inflammatory action and affects mitochondrial function in cells and tissues. In the present study, we analyzed the metabolic profile of BV2 and primary mouse microglia exposed to the CO-releasing molecules CORM-401 and CORM-A1 and investigated whether CO affects the metabolic adaptation of cells to the inflammatory stimulus lipopolysaccharide (LPS). Microglia respiration and glycolysis were measured using an Extracellular Flux Analyzer to provide a real-time bioenergetic assessment, and biochemical parameters were evaluated to define the metabolic status of the cells under normal or inflammatory conditions. We show that CO prevents LPS-induced depression of microglia respiration and reduction in ATP levels while altering the early expression of inflammatory markers, suggesting the metabolic changes induced by CO are associated with control of inflammation. CO alone affects microglia respiration depending on the concentration, as low levels increase oxygen consumption while higher amounts inhibit respiration. Increased oxygen consumption was attributed to an uncoupling activity observed in cells, at the molecular level (respiratory complex activities) and during challenge with LPS. Thus, application of CO is a potential countermeasure to reverse the metabolic changes that occur during microglia inflammation and in turn modulate their inflammatory profile.

of the lateral ventricle and striatum of the subventricular zone (SVZ) and on subgranular zone (SGZ) of the dentate gyrus (DG) in the hippocampus, where they can differentiate and persist for long periods of time [2, 3]. Neurons generated in the SVZ migrate to the olfactory bulb and differentiate into interneurons. However, NSC proliferation and neuroblast formation in SVZ decrease in aged animals [4-6]. Furthermore, neurogenesis in the SGZ gives rise to neurons in the granule cell layer (GCL) [7]. In addition to in vivo studies, NSCs have been isolated from the adult brain and cultured in vitro in order to extensively characterize them at different developmental stages [8-10]. NSCs can differentiate into neurons under defined culture conditions and are able to form synapses between each other or with already differentiated and mature neu-rons present in the cell culture [11-14]. Also, NSCs can generate astrocytes and oligodendrocytes [15, 16] depending on culture conditions. At least five steps appear to be involved in the neuro-genesis process: (a) proliferation of stem/progenitor cells, (b) migration of newborn neurons, (c) neuronal differentiation and maturation, (d) integration into neuronal circuits and (e) survival of cells [15]. The integration of newly born neurons into the mature hippocampal network and the physiological implications of adult neurogenesis are far less understood. Anatomical studies have shown that the newly born neurons receive synaptic inputs on their dendritic arbors and send axonal projections toward their normal targets, namely the CA3 pyramidal cells [17]. Elec-trophysiological recordings suggest that CA3 pyramidal cells develop functional properties of mature dentate granule cells [18]. Furthermore, neurogenesis in the adult hip-pocampus has been correlated with learning and memory in some hippocampus-dependent behavioral studies [11, 19, 20]. Abstract Brain is the major consumer of glucose in the human body, whose pattern of consumption changes through lifetime, decreasing during adolescence up to adult-hood. This evidence leads to the hypothesis that, in cerebral developmental stages, glycolysis might be the driving force for the high-energy requirement. Furthermore, several studies claim that neurogenesis process is accompanied by a shift into mitochondrial oxidative metabolism. Herein, we discuss recent work about cell metabolism during neuronal differentiation process, in particular the mitochondrial role in cellular bioenergy dynamics.

The neuroprotective role of carbon monoxide (CO) has been studied in a cell-autonomous mode. Herein, a new concept is disclosed-CO affects astrocyte-neuron communication in a paracrine manner to promote neuroprotection. Neuronal survival was assessed when co-cultured with astrocytes that had been pre-treated or not with CO. The CO-pre-treated astrocytes reduced neuronal cell death, and the cellular mechanisms were investigated, focusing on purinergic signaling. CO modulates astrocytic metabolism and extracellular ATP content in the co-culture medium. Moreover, several antagonists of P1 adenosine and P2 ATP receptors partially reverted CO-induced neuroprotection through astrocytes. Likewise, knocking down expression of the neuronal P1 adenosine receptor A 2A-R (encoded by Adora2a) reverted the neuroprotective effects of CO-exposed astrocytes. The neuroprotection of CO-treated astrocytes also decreased following prevention of ATP or adenosine release from astrocytic cells and inhibition of extracellular ATP metabolism into adenosine. Finally, the neuronal downstream event involves TrkB (also known as NTRK2) receptors and BDNF. Pharmacological and genetic inhibition of TrkB receptors reverts neuroprotection triggered by CO-treated astrocytes. Furthermore, the neuronal ratio of BDNF to pro-BDNF increased in the presence of CO-treated astrocytes and decreased whenever A 2A-R expression was silenced. In summary, CO prevents neuronal cell death in a paracrine manner by targeting astrocytic metabolism through purinergic signaling.

Purpose Blackberry ingestion has been demonstrated to attenuate brain degenerative processes with the benefits ascribed to the (poly)phenolic components. The aim of this work was to evaluate the neuroprotective potential of two wild blackberry species in a neurodegeneration cell model and compare them with a commercial variety. Methods This work encompasses chemical characterization before and after an in vitro digestion and the assessment of neuroprotection by digested metabolites. Some studies targeting redox/cell death systems were also performed to assess possible neuroprotective molecular mechanisms. Results The three blackberry extracts presented some quantitative differences in polyphenol composition that could be responsible for the different responses in the neurodegeneration cell model. Commercial blackberry extracts were ineffective but both wild blackberries, Rubus brigantinus and Rubus vagabundus, presented neuropro-tective effects. It was verified that a diminishment of intracellular ROS levels, modulation of glutathione levels and activation of caspases occurred during treatment. The last effect suggests a preconditioning effect since caspase activation was not accompanied by diminution in cell death and loss of functionality. Conclusions This is the first time that metabolites obtained from an in vitro digested food matrix, and tested at levels approaching the concentrations found in human plasma, have been described as inducing an adaptative response.

Hypertension is associated with cerebrovascular disease, white matter lesion and cognitive deficit, both in experimental models and clinical observations. Furthermore, in non-clinical models it is shown that hippocampus is affected by hypertension and hypoxia. Herein, two distinct hypertension models were used to study neurogenic response in hippocampus. Dahl salt sensitive (DSS) rat model is a genetic based idiopathic model, while chronic intermittent hypoxia (CIH) mimics the hypertension observed in patients with obstructive sleep apnea (OSA). Both models are chronic and trigger hypertension. No macroscopic alterations based on histological analysis were found in hippocampus derived from DSS and CIH exposure rats. Nevertheless, in hippocampus derived from CIH-induced hypertensive rats, there was a decrease on neuronal population (MAP2 and NeuN positive cells) and an increase on astrocytic marker GFAP. Accordingly, a higher increase on Ki67 expressing cells was found in dentate gyrus (DG) region, suggesting an enhancement of cell proliferation, concomitantly with an increase of Nestin staining, which indicates the presence of immature neurons under differentiation. While, in hippocampus of DSS rats with or without high salt diet, there was no remarkable difference indicating potential neuronal loss, astrocytic activation or neurogenesis. Furthermore, in both models hypertension did not alter the levels of expression of the stress response enzyme heme oxygenase-1 in DG. These data indicate that intermittent hypoxia might be the key factor involved in neurogenesis modulation in hippocampus. Furthermore , two hypotheses can be explored: (i) activation of neurogenesis is a response against neuronal loss induced by hypertension and/or hypoxia or (ii) neurogenesis can be directly stimulated by hypoxia as a neuroprotective mechanism.

The process of cell differentiation goes hand-in-hand with metabolic adaptations, which are needed to provide energy and new metabolites. Carbon monoxide (CO) is an endoge-nous cytoprotective molecule able to inhibit cell death and improve mitochondrial metabolism. Neuronal differentiation processes were studied using the NT2 cell line, which is derived from human testicular embryonic teratocarcinoma and differentiates into post-mitotic neurons upon retinoic acid treatment. CO-releasing molecule A1 (CORM-A1) was used do deliver CO into cell culture. CO treatment improved NT2 neuronal differentiation and yield, since there were more neurons and the total cell number increased following the differentiation process. CO supplementation enhanced the mitochondrial population in post-mitotic neurons derived from NT2 cells, as indicated by an increase in mitochondrial DNA. CO treatment during neuronal differentiation increased the extent of the classical metabolic change that occurs during neuronal differentiation, from glycolytic to more oxidative metabolism, by decreasing the ratio of lactate production and glucose consumption. The expression of pyruvate and lactate dehydrogenases was higher, indicating an augmented oxidative metabolism. Moreover, these findings were corroborated by an increased percentage of 13 C incorporation from [U-13 C]glucose into the tricarboxylic acid cycle metabolites malate and citrate, and also glutamate and aspartate in CO-treated cells. Finally, under low levels of oxygen (5%), which enhances glycolytic metabolism, some of the enhancing effects of CO on mitochondria were not observed. In conclusion , our data show that CO improves neuronal and mito-chondrial yield by stimulation of tricarboxylic acid cycle activity, and thus oxidative metabolism of NT2 cells during the process of neuronal differentiation.

Cerebral ischemia and neurodegenerative diseases lead to impairment or death of neurons in the central nervous system. Stem cell based therapies are promising strategies currently under investigation. Carbon monoxide (CO) is an endogenous product of heme degradation by heme oxygenase (HO) activity. Administration of CO at low concentrations produces several beneficial effects in distinct tissues, namely anti-apoptotic and anti-inflammatory. Herein the CO role on modulation of neuronal differentiation was assessed. Three different models with increasing complexity were used: human neuroblastoma SH-S5Y5 cell line, human teratocarcinoma NT2 cell line and organotypic hippocampal slice cultures (OHSC). Cell lines were differentiated into post-mitotic neurons by treatment with retinoic acid (RA) supplemented with CO-releasing molecule A1 (CORM-A1). CORM-A1 positively modulated neuronal differentiation, since it increased final neuronal production and enhanced the expression of specific neuronal genes: Nestin, Tuj1 and MAP2. Furthermore, during neuro-nal differentiation process, there was an increase in proliferative cell number (ki67 mRNA expressing cells) and a decrease in cell death (lower propidium iodide (PI) uptake, limitation of caspase-3 activation and higher Bcl-2 expressing cells). CO supplementation did not increase the expression of RA receptors. In the case of SH-S5Y5 model, small amounts of reactive oxygen species (ROS) generation emerges as important signaling molecules during CO-promoted neuronal differentiation. CO's improvement of neuronal differentiation yield was validated using OHSC as ex vivo model. CORM-A1 treatment of OHSC promoted higher levels of cells expressing the neuronal marker Tuj1. Still, CORM-A1 increased cell proliferation assessed by ki67 expression and also prevented cell death, which was followed by increased Bcl-2 expression, decreased levels of active caspase-3 and PI uptake. Likewise, ROS signaling emerged as key factors in CO's increasing number of differentiated neurons in OHSC. In conclusion, CO's increasing number of differentiated neurons is PLOS ONE |