Circadian disruption alters gut barrier integrity via a ß-catenin-MMP-related pathway.

We evaluated the mechanistic link between circadian rhythms and gut barrier permeability. Mice were subjected to either constant 24-h light (LL) or 12-h light/dark cycles (LD). Mice housed in LL experienced a significant increase in gut barrier permeability that was associated with dysregulated ß-catenin expression and altered expression of tight junction (TJ) proteins. Silencing of ß-catenin resulted in disruption of barrier function in SW480 cells, with ß-catenin appearing to be an upstream regulator of the core circadian components, such as Bmal1, Clock, and Per1/2. In addition, ß-catenin silencing downregulated ZO-1 and occludin TJ proteins with only limited or no changes at their mRNA levels, suggesting post transcriptional regulation. Indeed, silencing of ß-catenin significantly upregulated expression of matrix metallopeptidase (MMP)-2 and MMP-9, and blocking MMP-2/9 activity attenuated epithelial disruption induced by ß-catenin silencing. These results indicate the regulatory role of circadian disruption on gut barrier integrity and the associations between TJ proteins and circadian rhythms, while demonstrating the regulatory role of ß-catenin in this process.

The Flavonoid Rich Black Currant (Ribes nigrum) Ethanolic Gemmotherapy Extract Elicits Neuroprotective Effect by Preventing Microglial Body Swelling in Hippocampus and Reduces Serum TNF-α Level: Pilot Study.

Many plant-derived flavonoids are known for their anti-neuroinflammatory and anti-neurodegenerative effects. The fruits and leaves of the black currant (BC, Ribes nigrum) contain these phytochemicals with therapeutic benefits. The current study presents a report on a standardized BC gemmotherapy extract (BC-GTE) that is prepared from fresh buds. It provides details about the phytoconstituent profile specific to the extract as well as the associated antioxidant and anti-neuroinflammatory properties. The reported BC-GTE was found to contain approximately 133 phytonutrients, making it unique in its composition. Furthermore, this is the first report to quantify the presence of significant flavonoids such as luteolin, quercetin, apigenin, and kaempferol. Drosophila melanogaster-based tests revealed no cytotoxic but nutritive effects. We also demonstrated that adult male Wistar rats, pretreated with the analyzed BC-GTE and assessed after lipopolysaccharide (LPS) injection, did not show any apparent increase in body size in the microglial cells located in the hippocampal CA1 region, while in control experiments, the activation of microglia was evident. Moreover, no elevated levels of serum-specific TNF-α were observed under the LPS-induced neuroinflammatory condition. The analyzed BC-GTE's specific flavonoid content, along with the experimental data based on an LPS-induced inflammatory model, suggest that it possesses anti-neuroinflammatory/neuroprotective properties. This indicates that the studied BC-GTE has the potential to be used as a GTE-based complementary therapeutic approach.

Expression of SARS-CoV-2-related receptors in cells of the neurovascular unit: implications for HIV-1 infection.

BACKGROUND: Neurological complications are common in patients affected by COVID-19 due to the ability of SARS-CoV-2 to infect brains. While the mechanisms of this process are not fully understood, it has been proposed that SARS-CoV-2 can infect the cells of the neurovascular unit (NVU), which form the blood-brain barrier (BBB). The aim of the current study was to analyze the expression pattern of the main SARS-CoV-2 receptors in naïve and HIV-1-infected cells of the NVU in order to elucidate a possible pathway of the virus entry into the brain and a potential modulatory impact of HIV-1 in this process. METHODS: The gene and protein expression profile of ACE2, TMPRSS2, ADAM17, BSG, DPP4, AGTR2, ANPEP, cathepsin B, and cathepsin L was assessed by qPCR, immunoblotting, and immunostaining, respectively. In addition, we investigated if brain endothelial cells can be affected by the exposure to the S1 subunit of the S protein, the domain responsible for the direct binding of SARS-CoV-2 to the ACE2 receptors. RESULTS: The receptors involved in SARS-CoV-2 infection are co-expressed in the cells of the NVU, especially in astrocytes and microglial cells. These receptors are functionally active as exposure of endothelial cells to the SARS CoV-2 S1 protein subunit altered the expression pattern of tight junction proteins, such as claudin-5 and ZO-1. Additionally, HIV-1 infection upregulated ACE2 and TMPRSS2 expression in brain astrocytes and microglia cells. CONCLUSIONS: These findings provide key insight into SARS-CoV-2 recognition by cells of the NVU and may help to develop possible treatment of CNS complications of COVID-19.

Exercise combined with a probiotics treatment alters the microbiome, but moderately affects signalling pathways in the liver of male APP/PS1 transgenic mice.

It has been demonstrated that physical exercise and probiotic supplementation delay the progress of Alzheimer's Disease (AD) in male APP/PS1TG mice. However, it has also been suggested that both exercise and AD have systemic effects. We have studied the effects of exercise training and probiotic treatment on microbiome and biochemical signalling proteins in the liver. The results suggest that liver is under oxidative stress, since SOD2 levels of APP/PS1 mice were decreased when compared to a wild type of mice. Exercise training prevented this decrease. We did not find significant changes in COX4, SIRT3, PGC-1a or GLUT4 levels, while the changes in pAMPK/AMPK, pmTOR/mTOR, pS6/S6 and NRF2 levels were randomly modulated. The data suggest that exercise and probiotics-induced changes in microbiome do not strongly affect mitochondrial density or protein synthesis-related AMPK/mTOR/S6 pathways in the liver of these animals.

Circadian control of polycyclic aromatic hydrocarbon-induced dysregulation of endothelial tight junctions and mitochondrial bioenergetics.

The study evaluates the impact of environmental toxicants, such as polycyclic aromatic hydrocarbons (PAHs), on circadian regulations and functions of brain endothelial cells, which form the main structural element of the blood-brain barrier (BBB). PAH are lipophilic and highly toxic environmental pollutants that accumulate in human and animal tissues. Environmental factors related to climate change, such as an increase in frequency and intensity of wildfires or enhanced strength of hurricanes or tropical cyclones, may lead to redistribution of these toxicants and enhanced human exposure. These natural disasters are also associated with disruption of circadian rhythms in affected populations, linking increased exposure to environmental toxicants to alterations of circadian rhythm pathways. Several vital physiological processes are coordinated by circadian rhythms, and disruption of the circadian clock can contribute to the development of several diseases. The blood-brain barrier (BBB) is crucial for protecting the brain from blood-borne harmful substances, and its integrity is influenced by circadian rhythms. Exposure of brain endothelial cells to a human and environmentally-relevant PAH mixture resulted in dose-dependent alterations of expression of critical circadian modulators, such as Clock, Bmal1, Cry1/2, and Per1/2. Moreover, silencing of the circadian Clock gene potentiated the impact of PAHs on the expression of the main tight junction genes and proteins (namely, claudin-5, occludin, JAM-2, and ZO-2), as well as mitochondrial bioenergetics. Findings from this study contribute to a better understanding of pathological influence of PAH-induced health effects, especially those related to circadian rhythm disruption.

MITOCHONDRIAL ANTIVIRAL PATHWAYS CONTROL ANTI-HIV RESPONSES AND ISCHEMIC STROKE OUTCOMES VIA THE RIG-1 SIGNALING AND INNATE IMMUNITY MECHANISMS.

Occludin (ocln) is one of the main regulatory cells of the blood-brain barrier (BBB). Ocln silencing resulted in alterations of the gene expression signatures of a variety of genes of the innate immunity system, including IFN-stimulated genes (ISGs) and the antiviral retinoic acid-inducible gene-1 (RIG-1) signaling pathway, which functions as a regulator of the cytoplasmic sensors upstream of the mitochondrial antiviral signaling protein (MAVS). Indeed, we observed dysfunctional mitochondrial bioenergetics, dynamics, and autophagy in our system. Alterations of mitochondrial bioenergetics and innate immune protection translated into worsened ischemic stroke outcomes in EcoHIV-infected ocln deficient mice. Overall, these results allow for a better understanding of the molecular mechanisms of viral infection in the brain and describe a previously unrecognized role of ocln as a key factor in the control of innate immune responses and mitochondrial dynamics, which affect cerebral vascular diseases such as ischemic stroke.

Exposure to polychlorinated biphenyls selectively dysregulates endothelial circadian clock and endothelial toxicity.

Polychlorinated biphenyls (PCBs) are lipophilic and persistent environmental toxicants, which pose health threats to the exposed population. Among several organs and cell types, vascular tissue and endothelial cells are especially prone to PCB-induced toxicity. Exposure to PCBs can exert detrimental impacts on biological pathways, expression of transcription factors, and tight junction proteins that are integral to the functionality of endothelial cells. Because biological and cellular processes are tightly regulated by circadian rhythms, and disruption of the circadian system may cause several diseases, we evaluated if exposure to PCBs can alter the expression of the major endothelial circadian regulators. In addition, we studied if dysregulation of circadian rhythms by silencing the brain and muscle ARNT-like 1 (Bmal1) gene can contribute to alterations of brain endothelial cells in response to PCB treatment. We demonstrated that diminished expression of Bmal1 enhances PCB-induced dysregulation of tight junction complexes, such as the expression of occludin, JAM-2, ZO-1, and ZO-2 especially at pathologically relevant longer PCB exposure times. Overall, the obtained results imply that dysregulation of the circadian clock is involved in endothelial toxicity of PCBs. The findings provide new insights for toxicological studies focused on the interactions between environmental pollutants and regulation of circadian rhythms.

Occludin: a gatekeeper of brain Infection by HIV-1.

Compromised structure and function of the blood-brain barrier (BBB) is one of the pathological hallmarks of brain infection by HIV-1. BBB damage during HIV-1 infection has been associated with modified expression of tight junction (TJ) proteins, including occludin. Recent evidence indicated occludin as a redox-sensitive, multifunctional protein that can act as both an NADH oxidase and influence cellular metabolism through AMPK kinase. One of the newly identified functions of occludin is its involvement in regulating HIV-1 infection. Studies suggest that occludin expression levels and the rate of HIV-1 infection share a reverse, bidirectional relationship; however, the mechanisms of this relationship are unclear. In this review, we describe the pathways involved in the regulation of HIV-1 infection by occludin. We propose that occludin may serve as a potential therapeutic target to control HIV-1 infection and to improve the lives of people living with HIV-1.

Occludin regulates HIV-1 infection by modulation of the interferon stimulated OAS gene family.

HIV-1-associated blood brain barrier (BBB) alterations and neurocognitive disorders are frequent clinical manifestations in HIV-1 infected patients. The BBB is formed by cells of the neurovascular unit (NVU) and sealed together by tight junction (TJ) proteins, such as occludin (ocln). Pericytes are a key cell type of NVU that can harbor HIV-1 infection via a mechanism that is regulated, at least in part, by ocln. After viral infection, the immune system starts the production of interferons, which induce the expression of the 2'-5'-oligoadenylate synthetase (OAS) family of interferon stimulated genes and activate the endoribonuclease RNaseL that provides antiviral protection by viral RNA degradation. The current study evaluated the involvement of the OAS genes in HIV-1 infection of cells of NVU and the role of ocln in controlling OAS antiviral signaling pathway. We identified that ocln modulates the expression levels of the OAS1, OAS2, OAS3, and OASL genes and proteins and, in turn, that the members of the OAS family can influence HIV replication in human brain pericytes. Mechanistically, this effect was regulated via the STAT signaling. HIV-1 infection of pericytes significantly upregulated expression of all OAS genes at the mRNA level but selectively OAS1, OAS2 and OAS3 at the protein level. Interestingly no changes were found in RNaseL after HIV-1 infection. Overall, these results contribute to a better understanding of the molecular mechanisms implicated in the regulation of HIV-1 infection in human brain pericytes and suggest a novel role for ocln in controlling of this process.

Occludin Regulates HIV-1 Infection by Modulation of the Interferon Stimulated OAS Gene Family.

HIV-1-associated blood brain barrier (BBB) alterations and neurocognitive disorders are frequent clinical manifestations in HIV-1 infected patients. The BBB is formed by cells of the neurovascular unit (NVU) and sealed together by tight junction proteins, such as occludin (ocln). Pericytes are a key cell type of NVU that can harbor HIV-1 infection via a mechanism that is regulated, at least in part, by ocln. After viral infection, the immune system starts the production of interferons, which induce the expression of the 2'-5'-oligoadenylate synthetase (OAS) family of interferon stimulated genes and activate the endoribonuclease RNaseL that provides antiviral protection by viral RNA degradation. The current study evaluated the involvement of the OAS genes in HIV-1 infection of cells of NVU and the role of ocln in controlling OAS antiviral signaling pathway. We identified that ocln modulates the expression levels of the OAS1, OAS2, OAS3, and OASL genes and proteins and, in turn, that the members of the OAS family can influence HIV replication in human brain pericytes. Mechanistically, this effect was regulated via the STAT signaling. HIV-1 infection of pericytes significantly upregulated expression of all OAS genes at the mRNA level but selectively OAS1, OAS2, and OAS3 at the protein level. Interestingly no changes were found in RNaseL after HIV-1 infection. Overall, these results contribute to a better understanding of the molecular mechanisms implicated in the regulation of HIV-1 infection in human brain pericytes and suggest a novel role for ocln in controlling of this process.

The NLRP3 inflammasome and gut dysbiosis as a putative link between HIV-1 infection and ischemic stroke.

HIV-associated comorbidities, such as ischemic stroke, are prevalent in people with HIV (PWH). Several studies both in animal models and humans have revealed an association between activation of the inflammasome in HIV-1 infection and stroke. The gut microbiota is an important component in controlling neuroinflammation in the CNS. It has also been proposed to be involved in the pathobiology of HIV-1 infection, and has been associated with an increase in activation of the inflammasome. In this review, we provide an overview of the microbiota-gut-inflammasome-brain axis, focusing on the NLRP3 inflammasome and dysregulation of the microbiome as risk factors that may contribute to the outcome of ischemic stroke and recovery in PWH. We also focus on the potential of targeting the NLRP3 inflammasome as a novel therapeutic approach for PWH who are at risk of developing cerebrovascular diseases.

DNA methylation clock DNAmFitAge shows regular exercise is associated with slower aging and systemic adaptation.

DNAmPhenoAge, DNAmGrimAge, and the newly developed DNAmFitAge are DNA methylation (DNAm)-based biomarkers that reflect the individual aging process. Here, we examine the relationship between physical fitness and DNAm-based biomarkers in adults aged 33-88 with a wide range of physical fitness (including athletes with long-term training history). Higher levels of VO2max (ρ = 0.2, p = 6.4E - 4, r = 0.19, p = 1.2E - 3), Jumpmax (p = 0.11, p = 5.5E - 2, r = 0.13, p = 2.8E - 2), Gripmax (ρ = 0.17, p = 3.5E - 3, r = 0.16, p = 5.6E - 3), and HDL levels (ρ = 0.18, p = 1.95E - 3, r = 0.19, p = 1.1E - 3) are associated with better verbal short-term memory. In addition, verbal short-term memory is associated with decelerated aging assessed with the new DNAm biomarker FitAgeAcceleration (ρ: - 0.18, p = 0.0017). DNAmFitAge can distinguish high-fitness individuals from low/medium-fitness individuals better than existing DNAm biomarkers and estimates a younger biological age in the high-fit males and females (1.5 and 2.0 years younger, respectively). Our research shows that regular physical exercise contributes to observable physiological and methylation differences which are beneficial to the aging process. DNAmFitAge has now emerged as a new biological marker of quality of life.

A Triple Primary Cell Culture Model of the Human Blood-Brain Barrier for Studying Ischemic Stroke In Vitro.

Ischemic stroke is a major cause of death and disability worldwide with limited therapeutic options. The neuropathology of ischemic stroke is characterized by an interruption in blood supply to the brain leading to cell death and cognitive dysfunction. During and after ischemic stroke, blood-brain barrier (BBB) dysfunction facilitates injury progression and contributes to poor patient recovery. Current BBB models primarily include endothelial monocultures and double co-cultures with either astrocytes or pericytes. Such models lack the ability to fully imitate a dynamic brain microenvironment, which is essential for cell-to-cell communication. Additionally, commonly used BBB models often contain immortalized human endothelial cells or animal-derived (rodent, porcine, or bovine) cell cultures that pose translational limitations. This paper describes a novel well-insert-based BBB model containing only primary human cells (brain microvascular endothelial cells, astrocytes, and brain vascular pericytes) enabling the investigation of ischemic brain injury in vitro. The effects of oxygen-glucose deprivation (OGD) on barrier integrity were assessed by passive permeability, transendothelial electrical resistance (TEER) measurements,and direct visualization of hypoxic cells. The presented protocol offers a distinct advantage inmimicking the intercellular environment of the BBB in vivo, serving as a more realistic in vitro BBB model for developing new therapeutic strategies in the setting of ischemic brain injury.

Effects of Long-Term Moderate Intensity Exercise on Cognitive Behaviors and Cholinergic Forebrain in the Aging Rat.

Physical exercise is now generally considered as a strategy to maintain cognitive abilities and to prevent age-related cognitive decline. In the present study, Wistar rats were subjected to moderate intensity treadmill exercise for 6 months prior to sacrifice at 12-, 24- and 32-month of age. This chronic physical intervention was tested on motility in the Open field (OF). Cognitive functions were measured in the Morris water maze (MWM) for spatial learning and in the Novel object recognition (NOR) tests. Since learning and memory are closely associated with cholinergic forebrain function ChAT fiber density after exercise training was assessed in hippocampus, and motor- and somatosensory cortical areas. Furthermore, quantification of ChAT-positive fiber aberrations as a neuropathological marker was also carried out in these brain areas. Our results show that in OF chronic exercise maintained horizontal locomotor activity in all age groups. Rearing activity, MWM and notably NOR performance were improved only in the 32-months old animals. Regarding cholinergic neuronal innervation, apart from a general age-related decline, exercise increased ChAT fiber density in the hippocampus CA1 area and in the motor cortex notably in the 32-months group. Massive ChAT fiber aberrations in all investigated areas which developed in senescence were clearly attenuated by exercise. The results suggest that moderate intensity chronic exercise in the rat is especially beneficial in advanced age. In conclusion, chronic exercise attenuates the age-related decline in cognitive and motor behaviors as well as age-related cholinergic fiber reduction, reduces malformations of cholinergic forebrain innervation.

Targeted single-cell electroporation loading of Ca2+ indicators in the mature hemicochlea preparation.

Ca2+ is an important intracellular messenger and regulator in both physiological and pathophysiological mechanisms in the hearing organ. Investigation of cellular Ca2+ homeostasis in the mature cochlea is hampered by the special anatomy and high vulnerability of the organ. A quick, straightforward and reliable Ca2+ imaging method with high spatial and temporal resolution in the mature organ of Corti is missing. Cell cultures or isolated cells do not preserve the special microenvironment and intercellular communication, while cochlear explants are excised from only a restricted portion of the organ of Corti and usually from neonatal pre-hearing murines. The hemicochlea, prepared from hearing mice allows tonotopic experimental approach on the radial perspective in the basal, middle and apical turns of the organ. We used the preparation recently for functional imaging in supporting cells of the organ of Corti after bulk loading of the Ca2+ indicator. However, bulk loading takes long time, is variable and non-selective, and causes the accumulation of the indicator in the extracellular space. In this study we show the improved labeling of supporting cells of the organ of Corti by targeted single-cell electroporation in mature mouse hemicochlea. Single-cell electroporation proved to be a reliable way of reducing the duration and variability of loading and allowed subcellular Ca2+ imaging by increasing the signal-to-noise ratio, while cell viability was retained during the experiments. We demonstrated the applicability of the method by measuring the effect of purinergic, TRPA1, TRPV1 and ACh receptor stimulation on intracellular Ca2+ concentration at the cellular and subcellular level. In agreement with previous results, ATP evoked reversible and repeatable Ca2+ transients in Deiters', Hensen's and Claudius' cells. TRPA1 and TRPV1 stimulation by AITC and capsaicin, respectively, failed to induce any Ca2+ response in the supporting cells, except in a single Hensen's cell in which AITC evoked transients with smaller amplitude. AITC also caused the displacement of the tissue. Carbachol, agonist of ACh receptors induced Ca2+ transients in about a third of Deiters' and fifth of Hensen's cells. Here we have presented a fast and cell-specific indicator loading method allowing subcellular functional Ca2+ imaging in supporting cells of the organ of Corti in the mature hemicochlea preparation, thus providing a straightforward tool for deciphering the poorly understood regulation of Ca2+ homeostasis in these cells.

Whole-body pulsed EMF stimulation improves cognitive and psychomotor activity in senescent rats.

During advanced aging passive exercise (PE) is becoming a valuable therapeutic intervention to improve physical and mental performances. In the present study chronic low frequency pulsed electromagnetic field (EMF) exposure was presented to senescent rats in order to clarify the behavioural effects related to cognitive and motility functions. Male Wistar rats of 30-32 months old were treated with EMF for six weeks, 3 times per week, 24 min per sessions prior to the age of 32 months. Stimulation intensities varied from 45 to 1250 µT. Psychomotility was estimated in an open field (OF), attention ability in novel object recognition (NOR), and spatial learning in the Morris water maze (MWM) tests. The results showed that EMF stimulation enhanced novelty-induced motility of vertical type, i.e. frequency of rearing activity was increased. In the cognitive tests EMF exposure increased attention-based discrimination in NOR and facilitated working memory type of spatial learning in the MWM tests. No undesirable type of side effects could be obtained even after the highest dose used. It is concluded that EMF stimulation in senescent age supports cognitive and psychomotor function in rats. The notion that PE may have complementary beneficial action on brain and motor functions in senescent age is strengthened by the present experimental results.