Digoxin Induces Human Astrocyte Reaction In Vitro.

Astrocyte reaction is a complex cellular process involving astrocytes in response to various types of CNS injury and a marker of neurotoxicity. It has been abundantly studied in rodents but relatively poorly in human cells due to limited access to the brain. Astrocytes play important roles in cerebral energy metabolism and are also key players in neuroinflammation. Astroglial metabolic and inflammatory changes have been reported with age, leading to the hypothesis that mitochondrial metabolism and inflammatory responses are interconnected. However, the relationship between energy metabolism and astrocyte reactivity in the context of neurotoxicity is not known. We hypothesized that changes in energy metabolism of astrocytes will be coupled to their activation by xenobiotics. Astrocyte reaction and associated energy metabolic changes were assessed by immunostaining, gene expression, proteomics, metabolomics, and extracellular flux analyses after 24 h of exposure of human ReN-derived astrocytes to digoxin (1-10 µM) or TNFα (30 ng/ml) used as a positive control. Strong astrocytic reaction was observed, accompanied by increased glycolysis at low concentrations of digoxin (0.1 and 0.5 µM) and after TNFα exposure, suggesting that increased glycolysis may be a common feature of reactive astrocytes, independent of the triggering molecule. In conclusion, whether astrocyte activation is triggered by cytokines or a xenobiotic, it is strongly tied to energy metabolism in human ReN-derived astrocytes. Increased glycolysis might be considered as an endpoint to detect astrocyte activation by potentially neurotoxic compounds in vitro. Finally, ReN-derived astrocytes may help to decipher mechanisms of neurotoxicity in ascertaining the ability of chemicals to directly target astrocytes.

Oxidative Stress and Extracellular Matrix Remodeling Are Signature Pathways of Extracellular Vesicles Released upon Morphine Exposure on Human Brain Microvascular Endothelial Cells.

Morphine, a commonly used antinociceptive drug in hospitals, is known to cross the blood-brain barrier (BBB) by first passing through brain endothelial cells. Despite its pain-relieving effect, morphine also has detrimental effects, such as the potential induction of redox imbalance in the brain. However, there is still insufficient evidence of these effects on the brain, particularly on the brain endothelial cells and the extracellular vesicles that they naturally release. Indeed, extracellular vesicles (EVs) are nanosized bioparticles produced by almost all cell types and are currently thought to reflect the physiological state of their parent cells. These vesicles have emerged as a promising source of biomarkers by indicating the functional or dysfunctional state of their parent cells and, thus, allowing a better understanding of the biological processes involved in an adverse state. However, there is very little information on the morphine effect on human brain microvascular endothelial cells (HBMECs), and even less on their released EVs. Therefore, the current study aimed at unraveling the detrimental mechanisms of morphine exposure (at 1, 10, 25, 50 and 100 µM) for 24 h on human brain microvascular endothelial cells as well as on their associated EVs. Isolation of EVs was carried out using an affinity-based method. Several orthogonal techniques (NTA, western blotting and proteomics analysis) were used to validate the EVs enrichment, quality and concentration. Data-independent mass spectrometry (DIA-MS)-based proteomics was applied in order to analyze the proteome modulations induced by morphine on HBMECs and EVs. We were able to quantify almost 5500 proteins in HBMECs and 1500 proteins in EVs, of which 256 and 148, respectively, were found to be differentially expressed in at least one condition. Pathway enrichment analysis revealed that the "cell adhesion and extracellular matrix remodeling" process and the "HIF1 pathway", a pathway related to oxidative stress responses, were significantly modulated upon morphine exposure in HBMECs and EVs. Altogether, the combination of proteomics and bioinformatics findings highlighted shared pathways between HBMECs exposed to morphine and their released EVs. These results put forward molecular signatures of morphine-induced toxicity in HBMECs that were also carried by EVs. Therefore, EVs could potentially be regarded as a useful tool to investigate brain endothelial cells dysfunction, and to a different extent, the BBB dysfunction in patient circulation using these "signature pathways".

Neurovascular Unit-Derived Extracellular Vesicles: From Their Physiopathological Roles to Their Clinical Applications in Acute Brain Injuries.

Extracellular vesicles (EVs) form a heterogeneous group of membrane-enclosed structures secreted by all cell types. EVs export encapsulated materials composed of proteins, lipids, and nucleic acids, making them a key mediator in cell-cell communication. In the context of the neurovascular unit (NVU), a tightly interacting multicellular brain complex, EVs play a role in intercellular communication and in maintaining NVU functionality. In addition, NVU-derived EVs can also impact peripheral tissues by crossing the blood-brain barrier (BBB) to reach the blood stream. As such, EVs have been shown to be involved in the physiopathology of numerous neurological diseases. The presence of NVU-released EVs in the systemic circulation offers an opportunity to discover new diagnostic and prognostic markers for those diseases. This review outlines the most recent studies reporting the role of NVU-derived EVs in physiological and pathological mechanisms of the NVU, focusing on neuroinflammation and neurodegenerative diseases. Then, the clinical application of EVs-containing molecules as biomarkers in acute brain injuries, such as stroke and traumatic brain injuries (TBI), is discussed.

Morphine-induced modulation of Nrf2-antioxidant response element signaling pathway in primary human brain microvascular endothelial cells.

Morphine is one of the most potent opioid analgesic used for pain treatment. Morphine action in the central nervous system requires crossing the blood-brain barrier. Due to the controversial relationship between morphine and oxidative stress, the potential pro- or antioxidant effects of morphine in the blood-brain barrier is important to be understood, as oxidative stress could cause its disruption and predispose to neurodegenerative diseases. However, investigation is scarce in human brain endothelial cells. Therefore, the present study evaluated the impact of morphine exposure at three different concentrations (1, 10 and 100 µM) for 24 h and 48 h on primary human brain microvascular endothelial cells. A quantitative data-independent acquisition mass spectrometry strategy was used to analyze proteome modulations. Almost 3000 proteins were quantified of which 217 were reported to be significantly regulated in at least one condition versus untreated control. Pathway enrichment analysis unveiled dysregulation of the Nrf2 pathway involved in oxidative stress response. Seahorse assay underlined mitochondria dysfunctions, which were supported by significant expression modulations of relevant mitochondrial proteins. In conclusion, our study revealed the dysregulation of the Nrf2 pathway and mitochondria dysfunctions after morphine exposure, highlighting a potential redox imbalance in human brain endothelial cells.

Ubiquinone Metabolism and Transcription HIF-1 Targets Pathway Are Toxicity Signature Pathways Present in Extracellular Vesicles of Paraquat-Exposed Human Brain Microvascular Endothelial Cells.

Over the last decade, the knowledge in extracellular vesicles (EVs) biogenesis and modulation has increasingly grown. As their content reflects the physiological state of their donor cells, these "intercellular messengers" progressively became a potential source of biomarker reflecting the host cell state. However, little is known about EVs released from the human brain microvascular endothelial cells (HBMECs). The current study aimed to isolate and characterize EVs from HBMECs and to analyze their EVs proteome modulation after paraquat (PQ) stimulation, a widely used herbicide known for its neurotoxic effect. Size distribution, concentration and presence of well-known EV markers were assessed. Identification and quantification of PQ-exposed EV proteins was conducted by data-independent acquisition mass spectrometry (DIA-MS). Signature pathways of PQ-treated EVs were analyzed by gene ontology terms and pathway enrichment. Results highlighted that EVs exposed to PQ have modulated pathways, namely the ubiquinone metabolism and the transcription HIF-1 targets. These pathways may be potential molecular signatures of the PQ-induced toxicity carried by EVs that are reflecting their cell of origin by transporting with them irreversible functional changes.

Nitrification of anaerobic digester effluent for nitrogen management at swine farms.

Anaerobic digester effluent collected from a swine farm was nitrified in lab-scale bioreactors mimicking an innovative manure management system to understand factors relevant to a successful start-up. The effects of digester effluent strength, aeration time, nitrifying sludge inoculation, and initial pH control on the startup of the nitrification system were investigated. The results showed that initial NH4+-N concentrations higher than 800 mg L−1 could severely inhibit the onset of nitrification if relying on native bacterial populations. When aeration time was increased from 4 to 12 h d−1, ammonium oxidation occurred earlier, but nitrite oxidation was delayed. However, the delay was not observed when bioaugmentation with nitrifying sludge was conducted. Initial addition of acid for pH control was unsuccessful as initial depletion of alkalinity eventually resulted in self-inhibition of nitrification cause by decreasing pH over time. Overall, these results provide guidance on how to effectively start large-scale innovative animal waste treatment systems.

Relationship between bone resorption, oxidative stress and inflammation in severe COPD exacerbation.

BACKGROUND: The natural course of chronic obstructive pulmonary disease (COPD) is complicated by the development of systemic consequences and co-morbidities. Increasing evidence indicates that COPD and osteoporosis are strongly linked. The common features in COPD pathology, history of smoking, age, inactivity, systemic inflammation, and use of systemic corticosteroids, are important risk factors for osteoporosis. METHODS: Pulmonary function, matrix metalloproteinase, tissue inhibitor of metalloproteinases, oxidative stress parameters, inflammatory markers and bone resorption marker were measured in 85 COPD patients and 47 healthy subjects. In patients, all parameters were assessed at two time points: one day after admission during exacerbation and about 30 days after, in the stable state of disease. RESULTS: In patients, bone resorption marker collagen type I ß-isomerized C-terminal telopeptide (beta CL) was increased during exacerbation: geometric mean 0.521, compared with stable patients 0.408, p<0.01, and control subjects 0.362 ng/ml, p<0.001. During exacerbation high sensitivity C-reactive protein (hsCRP) and neutrophil count were significantly higher in COPD patients compared with the control group, p<0.001. Matrix metalloproteinase-9 (MMP-9) and tissue inhibitor of metalloproteinase-1 (TIMP-1) concentrations were significantly higher in COPD patients, stable state or exacerbation, compared with control subjects, p<0.001. In patients during exacerbation, total oxidative status (TOS) was higher compared with the stable state, p<0.05 and control group, p<0.001. Multiple linear regression for the joint influence of inflammation, hypoxia and oxidative status during exacerbation showed almost 60% influence on the variability of beta CL concentrations. CONCLUSION: Intensification of disease characteristic symptoms such as inflammation, hypoxia, protease/antiprotease imbalance and oxidative stress, during exacerbation episodes in COPD patients may also contribute to increased bone resorption.

Pulmonary function, oxidative stress and inflammatory markers in severe COPD exacerbation.

BACKGROUND: Oxidative stress and inflammation play an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). OBJECTIVE: Pulmonary function, oxidative stress parameters and inflammatory markers were measured in 74 patients with severe COPD exacerbation and 41 healthy subjects. In patients all parameters were assessed at two time points: Firstly, one day after admission and secondly, after 7 10 days when they were clinically stable enough to be discharged. Patients were divided in two groups according the presence of ischemic heart disease (IHD): IHD positive (IHD+) patients and IHD negative (IHD-) patients. METHODS AND RESULTS: During hospitalisation O2•-, malondialdehyde (MDA), advanced oxidation protein products (AOPP) and total oxidant status (TOS) increased and were higher at discharge compared with admission and the control group. Superoxide dismutase (SOD) activity was significantly lower in COPD patients at both time points compared with the control group. Total antioxidant status (TAS) was significantly lower and the prooxidant-antioxidant balance (PAB) was higher at both time points in COPD patients compared with the control group. High sensitive C-reactive protein (hsCRP) and also the neutrophil count were significantly higher at admission compared with discharge. Paraoxonase 1 (PON1) enzymatic activities in COPD patients did not differ compared with the control group. IHD+ COPD patients had significantly lower PON1 activity but higher PAB levels and hsCRP concentrations, compared with IHD COPD patients. CONCLUSION: The oxidant/antioxidant imbalance was significantly pronounced in patients with COPD exacerbation for at least 24 hours following their admission and when they were clinically stable enough to be discharged. Increased oxidative stress, elevated systemic inflammation and decreased antioxidant defence were common in end-stage disease and particularly COPD patients with ischemic heart disease.