Nutraceutical agents with anti-inflammatory properties prevent dietary saturated-fat induced disturbances in blood-brain barrier function in wild-type mice

Preventive effects of a nutraceutical mixture of berberine, citrus and apple extracts on metabolic disturbances in Zucker fatty rats

BACKGROUND

The prevention of obesity represents a major health and socio-economic challenge. Nutraceuticals are regularly highlighted for their beneficial effects in preventing the metabolic disturbances associated with obesity. However, few studies have described the combined action of nutraceutical mixtures combining polyphenols with alkaloids.

OBJECTIVE

The aim of this study was to evaluate the effects of long-term dietary supplementation with a mixture of Berberine, Citrus and Apple extracts (BCA) in the primary prevention of obesity and its metabolic and vascular complications in the obese Zucker rat, a spontaneous model of genetic obesity and insulin resistance.

METHODS

Sixteen 8-week-old obese Zucker male rats were randomly divided into two groups: all rats received oral gavage daily either with water, untreated obese (U-ObZ) or BCA (BCA-ObZ) mixture for thirteen weeks. Morphological and metabolic parameters were measured along the study. Cumulative concentration-response curves to insulin, acetylcholine and phenylephrine were determined on isolated thoracic aorta. Colon permeability measurements were performed using the Ussing chamber technique. Fecal samples collected at the beginning and the end of the protocol were used as a template for amplification of the V3-V4 region of the 16S rDNA genes.

RESULTS

BCA supplementation reduced weight gain (p<0.05) and food intake (p<0.05) in the BCA-ObZ group rats compared to the U-ObZ group rats. It also improved glucose tolerance (p<0.001) and decreased fasting insulin and Homeostasis model assessment index (p<0.05). Through ex vivo experiments, the BCA mixture enhanced significantly aortic insulin relaxation (p<0.01), reduced α1-adrenoceptor-mediated vasoconstriction (p<0.01), and decreased distal colon permeability. Moreover, short-chain fatty acid producers such as Bacteroides, Blautia, and Akkermansia were found to be increased by the BCA mixture supplementation.

CONCLUSION

The results showed that a 13-week-supplementation with BCA mixture prevented weight gain and improved glucose metabolism in obese Zucker rats. We also demonstrated that BCA supplementation improved vascular function, colonic barrier permeability and gut microbiota profile.

Obesity-induced blood-brain barrier dysfunction: phenotypes and mechanisms

Obesity, a burgeoning global health issue, is increasingly recognized for its detrimental effects on the central nervous system, particularly concerning the integrity of the blood-brain barrier (BBB). This manuscript delves into the intricate relationship between obesity and BBB dysfunction, elucidating the underlying phenotypes and molecular mechanisms. We commence with an overview of the BBB's critical role in maintaining cerebral homeostasis and the pathological alterations induced by obesity. By employing a comprehensive literature review, we examine the structural and functional modifications of the BBB in the context of obesity, including increased permeability, altered transport mechanisms, and inflammatory responses. The manuscript highlights how obesity-induced systemic inflammation and metabolic dysregulation contribute to BBB disruption, thereby predisposing individuals to various neurological disorders. We further explore the potential pathways, such as oxidative stress and endothelial cell dysfunction, that mediate these changes. Our discussion culminates in the summary of current findings and the identification of knowledge gaps, paving the way for future research directions. This review underscores the significance of understanding BBB dysfunction in obesity, not only for its implications in neurodegenerative diseases but also for developing targeted therapeutic strategies to mitigate these effects.

Electroacupuncture stimulation ameliorates cognitive impairment induced by long-term high-fat diet by regulating microglial BDNF

Long-term high-fat diet (HFD) in adolescents leads to impaired hippocampal function and increases the risk of cognitive impairment. Studies have shown that HFD activates hippocampal microglia and induces hippocampal inflammation, which is an important factor for cognitive impairment. Electroacupuncture stimulation (ES), a nerve stimulation therapy, is anti-inflammatory. This study explored its therapeutic potential and mechanism of action in obesity-related cognitive impairment. 4-week-old C57 mice were given either normal or HFD for 22 weeks. At 19 weeks, some of the HFD mice were treated with ES and nigericin sodium salt. The cognitive behavior was assessed through Morris water maze test at 23 weeks. Western blotting was used to detect the expression levels of pro-inflammatory molecules IL-1β and IL-1R, synaptic plasticity related proteins synaptophysin and Postsynaptic Density-95 (PSD-95), and apoptotic molecules (Caspase-3 and Bcl-2), in the hippocampus. The number, morphology, and status of microglia, along with the brain-derived neurotrophic factor（BDNF） content, were analyzed using immunofluorescence. ES treatment improved cognitive deficits in HFD model mice, and decreased the expressions of microglial activation marker, CD68, and microglial BDNF. Inhibition of proinflammatory cytokine, IL-1β, and IL-1R promoted PSD-95 and synaptophysin expressions. Peripheral NLRP3 inflammasome agonist injections exacerbated the cognitive deficits in HFD mice and promoted the expressions of IL-1β and IL-1R in the hippocampus. The microglia showed obvious morphological damage and apoptosis. Collectively, our findings suggest that ES inhibits inflammation, regulates microglial BDNF, and causes remodeling of hippocampal function in mice to counteract obesity-like induced cognitive impairment. Overexcitation of peripheral inflammasome complexes induces hippocampal microglia apoptosis, which hinders the effects of ES.

Niacin modulates depressive-like behavior in experimental colitis through GPR109A-dependent mechanisms

AIMS

Depression is one of the common neurological comorbidities in patients with inflammatory bowel disease (IBD). The current study aimed to investigate the potential impact of niacin on colitis-induced depressive-like behavior in rats.

MATERIALS AND METHODS

Animals were given 5 % dextran sulfate sodium (DSS) in drinking water for one week to induce colitis. Niacin (80 mg/kg), with or without mepenzolate bromide (GPR109A blocker), was administered once per day throughout the experimental period. Rats were tested for behavioral changes using open field and forced swimming tests.

KEY FINDINGS

Niacin significantly ameliorated DSS-induced behavioral deficits and alleviated macroscopic and microscopic colonic inflammatory changes. It also augmented the hippocampal levels of ZO-1, occludin, and claudin-5 proteins, indicating the ability of niacin to restore the blood-brain barrier (BBB) integrity. Moreover, niacin decreased hippocampal IL-1ꞵ and NF-ĸB contents but increased GSH, Sirt-1, Nrf-2, HO-1 concentrations. All these beneficial effects were partially abolished by the co-administration of mepenzolate bromide.

SIGNIFICANCE

The neuroprotective effect of niacin against DSS-induced depressive-like behavior was partially mediated through GPR109A-mediated mechanisms. Such mechanisms are also involved in modulating neuronal oxidative stress and inflammation via Sirt-1/Nrf-2/HO-1 signaling pathways.

Administration of α-lipoic acid and silymarin attenuates aggression by modulating endocrine, oxidative stress and inflammatory pathways in mice

Aggression, a highly prevalent behavior among all the psychological disorders having strong association with psychiatric imbalance, neuroendocrine changes and neurological disturbances (including oxidative stress & neuroinflammation) require both pharmacological and non-pharmacological treatments. Focusing the preclinical neuroendocrine determinants of aggression, this interventional study was designed to elucidate the curative effect of antioxidants on aggression in male mice. Adult albino male mice (n = 140) randomly divided into two main treatment groups for α-lipoic acid (ALA) and silymarin with 5 subgroups (n = 10) for each curative study, namely control, disease (aggression-induced), standard (diazepam, 2.5 mg/kg), low dose (100 mg/kg) and high dose (200 mg/kg) treatment groups of selected antioxidants. Resident-intruder paradigm and levodopa (L-dopa 375 mg/kg, p.o.) induced models were used for aggression. Effect of antioxidant treatment (i.e., 21 days bid) on aggression was assessed by evaluating the changes in aggressive behavior, oxidative stress biomarkers superoxide dismutase, catalase, glutathione, nitrite and malondialdehyde (SOD, CAT, GSH, nitrite & MDA), neurotransmitters (dopamine, nor-adrenaline and serotonin), pro-inflammatory cytokines tumor necrosis factor-α and interleukin- 6 (TNF-α & IL-6) along with serum testosterone examination. This study showed potential ameliorative effect on aggressive behavior with both low (100 mg/kg) and high (200 mg/kg) doses of antioxidants (ALA & silymarin). Resident-intruder or L-dopa induced aggression in male mice was more significantly tuned with ALA treatment than silymarin via down regulating both oxidative stress and inflammatory biomarkers. ALA also exhibited notable effects in managing aggression-induced disturbances on plasma testosterone levels. In conclusion, ALA is more effective than silymarin in attenuating aggression in mice.

The Lipid Invasion Model: Growing Evidence for This New Explanation of Alzheimer's Disease

The Lipid Invasion Model (LIM) is a new hypothesis for Alzheimer's disease (AD) which argues that AD is a result of external lipid invasion to the brain, following damage to the blood-brain barrier (BBB). The LIM provides a comprehensive explanation of the observed neuropathologies associated with the disease, including the lipid irregularities first described by Alois Alzheimer himself, and accounts for the wide range of risk factors now identified with AD, all of which are also associated with damage to the BBB. This article summarizes the main arguments of the LIM, and new evidence and arguments in support of it. The LIM incorporates and extends the amyloid hypothesis, the current main explanation of the disease, but argues that the greatest cause of late-onset AD is not amyloid-β (Aβ) but bad cholesterol and free fatty acids, let into the brain by a damaged BBB. It suggests that the focus on Aβ is the reason why we have made so little progress in treating the disease in the last 30 years. As well as offering new perspectives for further research into the diagnosis, prevention, and treatment of AD, based on protecting and repairing the BBB, the LIM provides potential new insights into other neurodegenerative diseases such as Parkinson's disease and amyotrophic lateral sclerosis/motor neuron disease.

Lipidomic changes of cerebral cortex in aldehyde dehydrogenase-2 knock-in heterozygote mice after chronic alcohol exposure

Introduction

Alcohol is the main legal drug in the world, and excessive consumption of alcohol seriously damages the morphological structure and function of various organs. The insufficiency of an essential enzyme in ethanol metabolism, aldehyde dehydrogenase-2 (ALDH2), will aggravate the alcohol-induced brain injury. The effect of ALDH2 after chronic alcohol exposure on global lipid profiling of the brain remains unclear.

Methods

In this study, ALDH2*2 knock-in mice were fed the Lieber-DeCarli liquid diet containing ethanol for 8 weeks. Blood alcohol and acetaldehyde levels were examined, and the mice were tested through novel object recognition and the Y-maze test to evaluate cognitive impairment toward the end of the study. The lipidome profiling of cerebral cortex samples was investigated using a lipidomics method based on ultra-high performance liquid tandem chromatography quadrupole time of flight mass spectrometry (UHPLC-QTOFMS).

Results and Discussion

Compared with similarly treated wild-type (WT) mice, ALDH2*2 mice exhibited poor cognitive performance, though the result did not achieve statistical significance. The lipidomics results indicated that 74 differential lipid species were selected in WT mice, of which 57 species were up-regulated, and 17 were down-regulated. Moreover, 99 differential lipids were identified in ALDH2*2 mice, of which 73 were up-regulated, and 26 were down-regulated. For ALDH2*2 mice, the number of changed significantly glycerophospholipids (GPs) subtypes was lower than that of WT mice. Interestingly, compared with WT mice, a lower proportion of polyunsaturated fatty acids (PUFAs) was found in ALDH2*2 mice. Collectively, the results provide clear evidence for a lipidomic signature of marked changes in the cerebral cortex of ALDH2*2 mice after chronic alcohol exposure.

Highlights

• The cerebral cortex of heterozygous ALDH2*2 mice showed more significant changes in lipidome profiles after chronic alcohol exposure than wild-type mice.• Most lipids were significantly up-regulated in both groups of mice, whereas the increase in TAG was restricted to WT mice.• For ALDH2*2 mice, GPs substances changed significantly, and SHexCer and SM subclasses in sphingolipids also deserved attention.

Niacin mitigates blood-brain barrier tight junctional proteins dysregulation and cerebral inflammation in ketamine rat model of psychosis: Role of GPR109A receptor

Dysregulated inflammatory responses and blood-brain barrier (BBB) dysfunction are recognized as central factors in the development of psychiatric disorders. The present study was designed to evaluate the effect of niacin on BBB integrity in ketamine-induced model of psychosis. Meanwhile, mepenzolate bromide (MPN), a GPR109A receptor blocker, was used to investigate the role of this receptor on the observed niacin's effect. Male Wistar rats received ketamine (30 mg/kg/day, i.p) for 5 consecutive days and then niacin (40 mg/kg/day, p.o), with or without MPN (5 mg/kg/day, i.p), was given for the subsequent 15 days. Three days before the end of experiment, rats were behaviorally tested using open field, novel object recognition, social interaction, and forced swimming tests. Niacin significantly ameliorated ketamine-induced behavioral deficits, amended gamma aminobutyric acid and glutamate concentration, decreased tumor necrosis factor-α and matrix metallopeptidase 9 levels, and increased netrin-1 contents in the hippocampus of rats. Niacin also augmented the hippocampal expression of ZO-1, occludin, and claudin-5 proteins, indicating the ability of niacin to restore the BBB integrity. Moreover, the histopathologic changes in hippocampal neurons were alleviated. Since all the beneficial effects of niacin in the present investigation were partially abolished by the co-administration of MPN; GPR109A receptor was proven to partially mediate the observed antipsychotic effects of niacin. These data revealed that GPR109A-mediated signaling pathways might represent potential targets for therapeutic interventions to prevent or slow the progression of psychosis.

The neurovascular unit and systemic biology in stroke - implications for translation and treatment

Ischaemic stroke is a leading cause of disability and death for which no acute treatments exist beyond recanalization. The development of novel therapies has been repeatedly hindered by translational failures that have changed the way we think about tissue damage after stroke. What was initially a neuron-centric view has been replaced with the concept of the neurovascular unit (NVU), which encompasses neuronal, glial and vascular compartments, and the biphasic nature of neural-glial-vascular signalling. However, it is now clear that the brain is not the private niche it was traditionally thought to be and that the NVU interacts bidirectionally with systemic biology, such as systemic metabolism, the peripheral immune system and the gut microbiota. Furthermore, these interactions are profoundly modified by internal and external factors, such as ageing, temperature and day-night cycles. In this Review, we propose an extension of the concept of the NVU to include its dynamic interactions with systemic biology. We anticipate that this integrated view will lead to the identification of novel mechanisms of stroke pathophysiology, potentially explain previous translational failures, and improve stroke care by identifying new biomarkers of and treatment targets in stroke.

Short-term consumption of alcohol (vodka) mixed with energy drink (AMED) attenuated alcohol-induced cerebral capillary disturbances and neuroinflammation in adult wild-type mice

Background: The ingestion of combinatory Alcohol Mixed with Energy Drink (AMED) beverages continues to increase markedly, particularly among young adults. Some studies suggest detrimental health effects related to the combination of alcohol with energy drink formulations; however, the consumption of AMED has not been investigated in context of the cerebral microvasculature or neuroinflammation. We hypothesized that cerebral capillary integrity and glial cells are particularly vulnerable to the combination of AMED.Methods:12-week old wild-type C57BL/6J mice were orally gavaged with either vehicle (water), alcohol (vodka), an energy drink (Mother^TM), or a combination AMED, daily for five days. Thereafter, mice were sacrificed, blood alcohol concentrations were analysed and cryosections of brain specimens were subjected to confocal immunofluorescent analysis for measures of cerebral capillary integrity via immunoglobulin G (IgG), and markers of neuroinflammation, ionized-calcium-binding-adaptor-molecule 1 (Iba1) and Glial-Fibrillary-Acidic-Protein (GFAP). Proinflammatory cytokines, IL-2, IL-17A, IFN-ϒ, and anti-inflammatory cytokines, IL-4, IL-6 and IL-10, were also measured in serum.Results: Consistent with previous studies, cerebral capillary dysfunction and astroglial cell activation were markedly greater in the alcohol-only group (AO); however, the AO-induced effects were profoundly attenuated with the AMED combination. Mice maintained on AO and AMED interventions exhibited a moderate increase in microglial recruitment. There were no significant changes in pro-inflammatory nor anti-inflammatory cytokines in ED or AMED treated mice.Conclusion: This study suggests that paradoxically the acute detrimental effects of alcohol on cerebral capillary integrity and astrogliosis are counteracted with the co-provision of an ED, rich in caffeine and taurine and containing B-group vitamins.

Synthesis of human amyloid restricted to liver results in an Alzheimer disease-like neurodegenerative phenotype

Several lines of study suggest that peripheral metabolism of amyloid beta (Aß) is associated with risk for Alzheimer disease (AD). In blood, greater than 90% of Aß is complexed as an apolipoprotein, raising the possibility of a lipoprotein-mediated axis for AD risk. In this study, we report that genetic modification of C57BL/6J mice engineered to synthesise human Aß only in liver (hepatocyte-specific human amyloid (HSHA) strain) has marked neurodegeneration concomitant with capillary dysfunction, parenchymal extravasation of lipoprotein-Aß, and neurovascular inflammation. Moreover, the HSHA mice showed impaired performance in the passive avoidance test, suggesting impairment in hippocampal-dependent learning. Transmission electron microscopy shows marked neurovascular disruption in HSHA mice. This study provides causal evidence of a lipoprotein-Aß /capillary axis for onset and progression of a neurodegenerative process.

It has been suggested that peripheral metabolism of amyloid-beta is associated with risk for Alzheimer’s disease. This study reveals that the expression of human amyloid exclusively in the liver induces Alzheimer’s disease-like pathologies in mice, potentially indicating a completely novel pathway of Alzheimer’s disease aetiology and therapies.

Cognitive Deficits in Type-1 Diabetes: Aspects of Glucose, Cerebrovascular and Amyloid Involvement

The evidence shows that individuals with type-1 diabetes mellitus (T1DM) are at greater risk of accelerated cognitive impairment and dementia. Although, to date the mechanisms are largely unknown. An emerging body of literature indicates that dysfunction of cerebral neurovascular network and plasma dyshomeostasis of soluble amyloid-β in association with impaired lipid metabolism are central to the onset and progression of cognitive deficits and dementia. However, the latter has not been extensively considered in T1DM. Therefore, in this review, we summarised the literature concerning altered lipid metabolism and cerebrovascular function in T1DM as an implication for potential pathways leading to cognitive decline and dementia.

The Consumption of Energy Drinks Induces Blood-Brain Barrier Dysfunction in Wild-Type Mice

Energy drinks containing significant quantities of caffeine and sugar are increasingly consumed, particularly by adolescents and young adults. Chronic ingestion of energy drinks may potentially regulate vascular risk factors. This study investigated the effects of chronic ingestion of energy drinks on blood-brain barrier (BBB) integrity and neuroinflammation. Male C57BL/6J mice were maintained on water (control), Mother^TM (ED), sugar-free Mother^TM (sfED), or Coca Cola^TM soft drink (SD) for 13 weeks. The BBB integrity and neuroinflammation were analyzed with semi-quantitative immunofluorescent microscopy. Blood pressure, plasma inflammatory cytokine levels and blood glucose were also considered. Following 13 weeks of intervention, mice treated with ED, sfED, and SD showed significant disruption of BBB. However, marked neuroinflammation was observed only in sfED group mice. The consumption of ED and sfED significantly altered the blood pressure and plasma concentrations of inflammatory cytokines, TNF-a, IL-4, IL-6, and IL-10, and both increased plasma glucose. Correlation analyses showed significant associations between BBB dysfunction and hypotension, hyperglycaemia and cytokine dyshomeostasis. The intake of energy drink, particularly the sugar free formulation, may compromise the integrity of BBB and induce neuroinflammation via hypotension, hyperglycaemia and inflammatory pathways.

Blood-brain barrier disruption and ventricular enlargement are the earliest neuropathological changes in rats with repeated sub-concussive impacts over 2 weeks

Repeated sub-concussive impact (e.g. soccer ball heading), a significantly lighter form of mild traumatic brain injury, is increasingly suggested to cumulatively alter brain structure and compromise neurobehavioural function in the long-term. However, the underlying mechanisms whereby repeated long-term sub-concussion induces cerebral structural and neurobehavioural changes are currently unknown. Here, we utilised an established rat model to investigate the effects of repeated sub-concussion on size of lateral ventricles, cerebrovascular blood-brain barrier (BBB) integrity, neuroinflammation, oxidative stress, and biochemical distribution. Following repeated sub-concussion 3 days per week for 2 weeks, the rats showed significantly enlarged lateral ventricles compared with the rats receiving sham-only procedure. The sub-concussive rats also presented significant BBB dysfunction in the cerebral cortex and hippocampal formation, whilst neuromotor function assessed by beamwalk and rotarod tests were comparable to the sham rats. Immunofluorescent and spectroscopic microscopy analyses revealed no significant changes in neuroinflammation, oxidative stress, lipid distribution or protein aggregation, within the hippocampus and cortex. These data collectively indicate that repeated sub-concussion for 2 weeks induce significant ventriculomegaly and BBB disruption, preceding neuromotor deficits.

Diets and Cellular-Derived Microparticles: Weighing a Plausible Link With Cerebral Small Vessel Disease

Cerebral small vessel disease (CSVD) represents a spectrum of pathological processes of various etiologies affecting the brain microcirculation that can trigger neuroinflammation and the subsequent neurodegenerative cascade. Prevalent with aging, CSVD is a recognized risk factor for stroke, vascular dementia, Alzheimer disease, and Parkinson disease. Despite being the most common neurodegenerative condition with cerebrocardiovascular axis, understanding about it remains poor. Interestingly, modifiable risk factors such as unhealthy diet including high intake of processed food, high-fat foods, and animal by-products are known to influence the non-neural peripheral events, such as in the gastrointestinal tract and cardiovascular stress through cellular inflammation and oxidation. One key outcome from such events, among others, includes the cellular activations that lead to elevated levels of endogenous cellular-derived circulating microparticles (MPs). MPs can be produced from various cellular origins including leukocytes, platelets, endothelial cells, microbiota, and microglia. MPs could act as microthrombogenic procoagulant that served as a plausible culprit for the vulnerable end-artery microcirculation in the brain as the end-organ leading to CSVD manifestations. However, little attention has been paid on the potential role of MPs in the onset and progression of CSVD spectrum. Corroboratively, the formation of MPs is known to be influenced by diet-induced cellular stress. Thus, this review aims to appraise the body of evidence on the dietary-related impacts on circulating MPs from non-neural peripheral origins that could serve as a plausible microthrombosis in CSVD manifestation as a precursor of neurodegeneration. Here, we elaborate on the pathomechanical features of MPs in health and disease states; relevance of dietary patterns on MP release; preclinical studies pertaining to diet-based MPs contribution to disease; MP level as putative surrogates for early disease biomarkers; and lastly, the potential of MPs manipulation with diet-based approach as a novel preventive measure for CSVD in an aging society worldwide.

Interplay of Good Bacteria and Central Nervous System: Cognitive Aspects and Mechanistic Considerations

The human gastrointestinal tract hosts trillions of microorganisms that is called “gut microbiota.” The gut microbiota is involved in a wide variety of physiological features and functions of the body. Thus, it is not surprising that any damage to the gut microbiota is associated with disorders in different body systems. Probiotics, defined as living microorganisms with health benefits for the host, can support or restore the composition of the gut microbiota. Numerous investigations have proved a relationship between the gut microbiota with normal brain function as well as many brain diseases, in which cognitive dysfunction is a common clinical problem. On the other hand, increasing evidence suggests that the existence of a healthy gut microbiota is crucial for normal cognitive processing. In this regard, interplay of the gut microbiota and cognition has been under focus of recent researches. In the present paper, I review findings of the studies considering beneficial effects of either gut microbiota or probiotic bacteria on the brain cognitive function in the healthy and disease statuses.

B Vitamins and Their Role in Immune Regulation and Cancer

B group vitamins represent essential micronutrients for myriad metabolic and regulatory processes required for human health, serving as cofactors used by hundreds of enzymes that carry out essential functions such as energy metabolism, DNA and protein synthesis and other critical functions. B vitamins and their corresponding vitamers are universally essential for all cellular life forms, from bacteria to humans. Humans are unable to synthesize most B vitamins and are therefore dependent on their diet for these essential micronutrients. More recently, another source of B vitamins has been identified which is derived from portions of the 10¹³ bacterial cells inhabiting the gastrointestinal tract. Here we review the expanding literature examining the relationship between B vitamins and the immune system and diverse cancers. Evidence of B vitamin’s role in immune cell regulation has accumulated in recent years and may help to clarify the disparate findings of numerous studies attempting to link B vitamins to cancer development. Much work remains to be carried out to fully clarify these relationships as the complexity of B vitamins’ essential functions complicates an unequivocal assessment of their beneficial or detrimental effects in inflammation and cancers.

A Paradoxical Vasodilatory Nutraceutical Intervention for Prevention and Attenuation of Migraine-A Hypothetical Review

Studies suggest that migraine pain has a vascular component. The prevailing dogma is that peripheral vasoconstriction activates baroreceptors in central, large arteries. Dilatation of central vessels stimulates nociceptors and induces cortical spreading depression. Studies investigating nitric oxide (NO) donors support the indicated hypothesis that pain is amplified when acutely administered. In this review, we provide an alternate hypothesis which, if substantiated, may provide therapeutic opportunities for attenuating migraine frequency and severity. We suggest that in migraines, heightened sympathetic tone results in progressive central microvascular constriction. Suboptimal parenchymal blood flow, we suggest, activates nociceptors and triggers headache pain onset. Administration of NO donors could paradoxically promote constriction of the microvasculature as a consequence of larger upstream central artery vasodilatation. Inhibitors of NO production are reported to alleviate migraine pain. We describe how constriction of larger upstream arteries, induced by NO synthesis inhibitors, may result in a compensatory dilatory response of the microvasculature. The restoration of central capillary blood flow may be the primary mechanism for pain relief. Attenuating the propensity for central capillary constriction and promoting a more dilatory phenotype may reduce frequency and severity of migraines. Here, we propose consideration of two dietary nutraceuticals for reducing migraine risk: L-arginine and aged garlic extracts.

Lipoic Acid and Fish Oil Combination Potentiates Neuroinflammation and Oxidative Stress Regulation and Prevents Cognitive Decline of Rats After Sepsis

Sepsis causes organ dysfunction due to an infection, and it may impact the central nervous system. Neuroinflammation and oxidative stress are related to brain dysfunction after sepsis. Both processes affect microglia activation, neurotrophin production, and long-term cognition. Fish oil (FO) is an anti-inflammatory compound, and lipoic acid (LA) is a universal antioxidant substance. They exert neuroprotective roles when administered alone. We aimed at determining the effect of FO+LA combination on microglia activation and brain dysfunction after sepsis. Microglia cells from neonatal pups were co-treated with lipopolysaccharide (LPS) and FO or LA, alone or combined, for 24 h. Cytokine levels were measured. Wistar rats were subjected to sepsis by cecal ligation and perforation (CLP) and treated orally with FO, LA, or FO+LA. At 24 h after surgery, the hippocampus, prefrontal cortex, and total cortex were obtained and assayed for levels of cytokines, myeloperoxidase (MPO) activity, protein carbonyls, superoxide dismutase (SOD), and catalase (CAT) activity. At 10 days after surgery, brain-derived neurotrophic factor (BDNF) levels were determined and behavioral tests were performed. The combination diminished in vitro levels of pro-inflammatory cytokines. The combination reduced TNF-α in the cortex, IL-1β in the prefrontal cortex, as well as MPO activity, and decreased protein carbonyls formation in all structures. The combination enhanced catalase activity in the prefrontal cortex and hippocampus, elevated BDNF levels in all structures, and prevented behavioral impairment. In summary, the combination was effective in preventing cognitive damage by reducing neuroinflammation and oxidative stress and increasing BDNF levels.

Chronic Consumption of Bovine Dairy Milk Attenuates Dietary Saturated Fatty Acid-Induced Blood-Brain Barrier Dysfunction

Ingestion of Western-diets enriched in long chain saturated fatty acids (LCSFA) are associated with increased risk of blood-brain barrier (BBB) dysfunction and neurovascular inflammation. Potential mechanisms include vascular insult as a consequence of metabolic aberrations, or changes in capillary permeability resulting in brain parenchymal extravasation of pro-inflammatory molecules. Bovine dairy milk (BDM) is potentially a significant source of dietary LCSFA, however, BDM contains an array of bioactive molecules purported to have vascular anti-inflammatory properties. This study investigated the effects of full cream (4% total fat) and delipidated (skim) BDM on BBB integrity and neuroinflammation in wild-type mice. Mice consuming substantial amounts of full cream or skim BDM with LCSFA-enriched chow were dyslipidemic compared to control mice provided with standard chow and water. However, there was no evidence of BBB dysfunction or neuroinflammation indicated by parenchymal abundance of immunoglobulin G and microglial recruitment, respectively. Positive control mice maintained on an LCSFA-enriched diet derived from cocoa-butter and water, had marked BBB dysfunction, however, co-provision of both full cream and skim milk solutions effectively attenuated LCSFA-induced BBB dysfunction. In mice provided with low-fat chow and full cream BDM drinking solutions, there were substantial favorable changes in the concentration of plasma anti-inflammatory cytokines. This study suggests that consumption of BDM may confer potent vascular benefits through the neuroprotective properties exuded by the milk-fat globule membrane moiety of BDM.

Deletion of equilibrative nucleoside transporter-2 protects against lipopolysaccharide-induced neuroinflammation and blood-brain barrier dysfunction in mice

Neuroinflammation is a common pathological feature of many brain diseases and is a key mediator of blood-brain barrier (BBB) breakdown and neuropathogenesis. Adenosine is an endogenous immunomodulator, whose brain extracellular level is tightly controlled by equilibrative nucleoside transporters-1 (ENT1) and ENT2. This study was aimed to investigate the role of ENTs in the modulation of neuroinflammation and BBB function. The results showed that mRNA level of Ent2 was significantly more abundant than that of Ent1 in the brain (hippocampus, cerebral cortex, striatum, midbrain, and cerebellum) of wild-type (WT) mice. Ent2^-/- mice displayed higher extracellular adenosine level in the hippocampus than their littermate controls. Repeated lipopolysaccharide (LPS) treatment induced microglia activation, astrogliosis and upregulation of proinflammatory cytokines, along with aberrant BBB phenotypes (including reduced tight junction protein expression, pericyte loss, and immunoglobulin G extravasation) and neuronal apoptosis in the hippocampus of WT mice. Notably, Ent2^-/- mice displayed significant resistance to LPS-induced neuroinflammation, BBB breakdown, and neurotoxicity. These findings suggest that Ent2 is critical for the modulation of brain adenosine tone and deletion of Ent2 confers protection against LPS-induced neuroinflammation and neurovascular-associated injury.

Bioactive components from garlic on brain resiliency against neuroinflammation and neurodegeneration

Garlic (Allium sativum) has been widely used for culinary and medicinal purposes. Aged garlic extract (AGE) and sulfur-containing compounds, including S-allylcysteine (SAC) are well documented botanical active components of garlic. AGE is prepared by the prolonged extraction of fresh garlic with aqueous ethanol and is considered a nutritional supplement with potential to promote human health. SAC is a water-soluble organosulfur compound and the most abundant component of AGE. Studies have demonstrated that both AGE and SAC can exert neuroprotective effects against neuroinflammation and neurodegeneration. Another bioactive component in AGE is N-α-(1-deoxy-D-fructos-1-yl)-L-arginine (FruArg) although less is known about the metabolic activity of this compound. The main aim of this review was to provide an undated overview of the neuroprotective perspectives of these active garlic components (AGE, SAC and FruArg). Of interest, our studies and those of others indicate that both AGE and FruArg are involved in the regulation of gene transcription and protein expression. AGE has been shown to reverse 67% of the transcriptome alteration induced by endotoxins-lipopolysaccharide (LPS), and FruArg has been shown to account for the protective effects by reversing 55% of genes altered in a cell-based neuroinflammation paradigm stimulated by LPS in murine BV-2 microglial cells. AGE and FruArg can alleviate neuroinflammatory responses through a variety of signaling pathways, such as Toll-like receptor and interleukin (IL)-6 signaling, as well as by upregulating the nuclear factor erythroid 2-related factor 2 (Nrf2)-mediated oxidative stress pathways known to promote microglial resiliency against neuroinflammation and neurodegeneration. The capability of FruArg to pass through the blood-brain barrier further supports its potential as a therapeutic compound. In summary, these experimental results provide new insight into the understanding of the neuroprotective effects of garlic components in promoting brain resiliency for health benefits.

Oleanolic Acid Exerts a Neuroprotective Effect Against Microglial Cell Activation by Modulating Cytokine Release and Antioxidant Defense Systems

Microglia respond to adverse stimuli in order to restore brain homeostasis and, upon activation, they release a number of inflammatory mediators. Chronic microglial overactivation is related to neuroinflammation in Alzheimer's disease. In this work, we show that oleanolic acid (OA), a natural triterpene present in food and medicinal plants, attenuates the activation of BV2 microglial cells induced by lipopolysaccharide (LPS). Cell pretreatment with OA inhibited the release of IL-1β, IL-6, TNF-α, and NO, which was associated with the downregulation of the expression of genes encoding for these cytokines and inducible nitric oxide synthase (iNOS), and the reinforcement of the endogenous antioxidant cell defense. These findings advocate considering OA as a novel neuroprotective agent to inhibit oxidative stress and inflammatory response in activated microglia associated with Alzheimer's disease.

Lipoic Acid and Other Antioxidants as Therapies for Multiple Sclerosis

Oxidative stress (OS), when oxidative forces outweigh endogenous and nutritional antioxidant defenses, contributes to the pathophysiology of multiple sclerosis (MS). Evidence of OS is found during acute relapses, in active inflammatory lesions, and in chronic, longstanding plaques. OS results in both ongoing inflammation and neurodegeneration. Antioxidant therapies are a rational strategy for people with MS with all phenotypes and disease durations. PURPOSE OF REVIEW: To understand the function of OS in health and disease, to examine the contributions of OS to MS pathophysiology, and to review current evidence for the effects of selected antioxidant therapies in people with MS (PwMS) with a focus on lipoic acid (LA). RECENT FINDINGS: Studies of antioxidant interventions in both animal and in vivo models result in reductions in serum markers of OS and increases in levels and activity of antioxidant enzymes. Antioxidant trials in PwMS, while generally underpowered, detect short-term improvements in markers of OS and antioxidant defenses, and to a lesser extent, in clinical symptoms (fatigue, depression). The best evidence to date is a 2-year trial of LA in secondary progressive MS which demonstrated a significant reduction of whole-brain atrophy and trend toward improvement in walking speed. Antioxidant therapy is a promising approach to treat MS across the spectrum and duration of disease. Rigorous and well-powered trials are needed to determine their therapeutic benefits.

High-fat diet-induced lipidome perturbations in the cortex, hippocampus, hypothalamus, and olfactory bulb of mice

Given their important role in neuronal function, there has been an increasing focus on altered lipid levels in brain disorders. The effect of a high-fat (HF) diet on the lipid profiles of the cortex, hippocampus, hypothalamus, and olfactory bulb of the mouse brain was investigated using nanoflow ultrahigh pressure liquid chromatography-electrospray ionization-tandem mass spectrometry in the current study. For 8 weeks, two groups of 5-week-old mice were fed either an HF or normal diet (6 mice from each group analyzed as the F and N groups, respectively). The remaining mice in both groups then received a 4-week normal diet. Each group was then subdivided into two groups for another 4-week HF or normal diet. Quantitative analysis of 270 of the 359 lipids identified from brain tissue revealed that an HF diet significantly affected the brain lipidome in all brain regions that were analyzed. The HF diet significantly increased diacylglycerols, which play a role in insulin resistance in all regions that were analyzed. Although the HF diet increased most lipid species, the majority of phosphatidylserine species were decreased, while lysophosphatidylserine species, with the same acyl chain, were substantially increased. This result can be attributed to increased oxidative stress due to the HF diet. Further, weight-cycling (yo-yo effect) was found more critical for the perturbation of brain lipid profiles than weight gain without a preliminary experience of an HF diet. The present study reveals systematic alterations in brain lipid levels upon HF diet analyzed either by lipid class and molecular levels.

Cafeteria diet and probiotic therapy: cross talk among memory, neuroplasticity, serotonin receptors and gut microbiota in the rat

The western diet is known to have detrimental effects on cognition and the gut microbiota, but few studies have investigated how these may be related. Here, we examined whether a probiotic could prevent diet-induced memory deficits. Rats were pre-exposed to vehicle, low or high doses of VSL#3 for 2 weeks before half were switched from chow to a cafeteria diet (Caf) for 25 days; VSL#3 treatment continued until death. High-dose VSL#3 prevented the diet-induced memory deficits on the hippocampal-dependent place task, but the probiotic caused deficits on the perirhinal-dependent object task, irrespective of diet or dose. No differences were observed in anxiety-like behaviour on the elevated plus maze. Gut microbial diversity was dramatically decreased by Caf diet and here, VSL#3 was able to increase the abundance of some taxa contained in the probiotic such as Streptococcus and Lactobacillus and also other taxa including Butyrivibrio, which were decreased by the Caf diet. This affected the predicted profile of microbial metabolic pathways related to antioxidant and bile biosynthesis, and fat and carbohydrate metabolism. In the hippocampus, the Caf diet increased the expression of many genes related to neuroplasticity and serotonin receptor (5HT) 1A, which was normalised in Caf-High rats. Distance-based linear modelling showed that these genes were the best predictors of place memory, and related to microbiota principal component (PC) 1. Neuroplasticity genes in the perirhinal cortex were also affected and related to PC1 but object memory performance was correlated with perirhinal 5HT2C expression and microbiota PC3. These results show that probiotics can be beneficial in situations of gut dysbiosis where memory deficits are evident but may be detrimental in healthy subjects.

Diet, Gut Microbiota, and Vitamins D + A in Multiple Sclerosis

Central to the understanding of the relationships between diet, gut microbiota, and vitamins D and A in multiple sclerosis is low-grade inflammation, which is involved in all chronic inflammatory diseases and is influenced by each of the above effectors. We show that food components have either proinflammatory or anti-inflammatory effects and influence both the human metabolism (the "metabolome") and the composition of gut microbiota. Hypercaloric, high-animal-fat Western diets favor anabolism and change gut microbiota composition towards dysbiosis. Subsequent intestinal inflammation leads to leakage of the gut barrier, disruption of the blood-brain barrier, and neuroinflammation. Conversely, a vegetarian diet, rich in fiber, is coherent with gut eubiosis and a healthy condition. Vitamin D levels, mainly insufficient in a persistent low-grade inflammatory status, can be restored to optimal values only by administration of high amounts of cholecalciferol. At its optimal values (>30 ng/ml), vitamin D requires vitamin A for the binding to the vitamin D receptor and exert its anti-inflammatory action. Both vitamins must be supplied to the subjects lacking vitamin D. We conclude that nutrients, including the nondigestible dietary fibers, have a leading role in tackling the low-grade inflammation associated with chronic inflammatory diseases. Their action is mediated by gut microbiota and any microbial change induced by diet modifies host-microbe interactions in a consequent way, to improve the disease or worsen it.

Blood-Brain Barrier Dysfunction Precedes Cognitive Decline and Neurodegeneration in Diabetic Insulin Resistant Mouse Model: An Implication for Causal Link

Diabetic insulin resistance and pro-diabetic diet are reported to increase dementia risk through unknown mechanisms. Emerging evidence suggests that the integrity of blood-brain barrier (BBB) is central to the onset and progression of neurodegeneration and cognitive impairment. Therefore, the current study investigated the effect of pro-diabetic diets on cognitive dysfunction in association to BBB integrity and its putative mechanisms. In C57BL/6J mice chronically ingested with a diet enriched in fat and fructose (HFF), Morris Water Maze (MWM) test indicated no significant cognitive decline after 4 weeks of HFF feeding compared to low-fat (LF) fed control. However, at this stage, BBB dysfunction accompanied by heightened neuroinflammation in cortex and hippocampal regions was already evident. After 24 weeks, HFF fed mice showed significantly deteriorated cognitive function concomitant with substantial neurodegeneration, which both showed significant associations with increased BBB permeability. In addition, the data indicated that the loss of BBB tight junctions was significantly associated with heightened inflammation and leukocyte infiltration. The data collectively suggest that in mice maintained on pro-diabetic diet, the dysfunctional BBB associated to inflammation and leukocyte recruitment precedes the neurodegeneration and cognitive decline, possibly indicating causal association.

Genetic, Transcriptome, Proteomic, and Epidemiological Evidence for Blood-Brain Barrier Disruption and Polymicrobial Brain Invasion as Determinant Factors in Alzheimer's Disease

Diverse pathogens are detected in Alzheimer's disease (AD) brains. A bioinformatics survey showed that AD genome-wide association study (GWAS) genes (localized in bone marrow, immune locations and microglia) relate to multiple host/pathogen interactomes (Candida albicans, Cryptococcus neoformans, Bornavirus, Borrelia burgdorferri, cytomegalovirus, Ebola virus, HSV-1, HERV-W, HIV-1, Epstein-Barr, hepatitis C, influenza, Chlamydia pneumoniae, Porphyrymonas gingivalis, Helicobacter pylori, Toxoplasma gondii, Trypanosoma cruzi). These interactomes also relate to the AD hippocampal transcriptome and to plaque or tangle proteins. Upregulated AD hippocampal genes match those upregulated by multiple bacteria, viruses, fungi, or protozoa in immunocompetent cells. AD genes are enriched in GWAS datasets reflecting pathogen diversity, suggesting selection for pathogen resistance, as supported by the old age of AD patients, implying resistance to earlier infections. APOE4 is concentrated in regions of high parasitic burden and protects against childhood tropical infections and hepatitis C. Immune/inflammatory gain of function applies to APOE4, CR1, and TREM2 variants. AD genes are also expressed in the blood-brain barrier (BBB), which is disrupted by AD risk factors (age, alcohol, aluminum, concussion, cerebral hypoperfusion, diabetes, homocysteine, hypercholesterolemia, hypertension, obesity, pesticides, pollution, physical inactivity, sleep disruption, smoking) and by pathogens, directly or via olfactory routes to basal-forebrain BBB control centers. The BBB benefits from statins, NSAIDs, estrogen, melatonin, memantine, and the Mediterranean diet. Polymicrobial involvement is supported by upregulation of bacterial, viral, and fungal sensors/defenders in the AD brain, blood, or cerebrospinal fluid. AD serum amyloid-β autoantibodies may attenuate its antimicrobial effects favoring microbial survival and cerebral invasion leading to activation of neurodestructive immune/inflammatory processes, which may also be augmented by age-related immunosenescence. AD may thus respond to antibiotic, antifungal, or antiviral therapy.

Differential Effects of High-Protein Diets Derived from Soy and Casein on Blood-Brain Barrier Integrity in Wild-type Mice

A number of studies report that a diet high in protein influences cognitive performance, but the results are inconsistent. Studies demonstrated that protein from different food sources has differential effects on cognition. It is increasingly recognized that the integrity of cerebrovascular blood–brain barrier (BBB) is pivotal for central nervous system function. However, to date, no studies have reported the effects of high-protein diets on BBB integrity. Therefore, in this study, the effects of diets enriched in casein or soy protein on BBB permeability were investigated. Immunomicroscopy analyses of cerebral parenchymal immunoglobulin G extravasation indicated significant BBB disruption in the cortex of young adult mice maintained on high-casein diet for 12 weeks, while no signs of BBB dysfunction were observed in mice fed with control or high-soy protein diet. Moreover, cortical expression of glial fibrillary acidic protein (GFAP) was significantly greater in mice fed the high-casein diet compared to control mice, indicating heightened astrocyte activation, whereas mice maintained on a soy-enriched diet showed no increase of GFAP abundance. Plasma concentrations of homocysteine were markedly greater in mice maintained on a high-casein diet in comparison to control mice. Collectively, these findings suggest that a diet enriched in casein but not soy protein may induce astrocyte activation through exaggerated BBB permeability by increased plasma homocysteine. The outcomes indicate the differential effects of protein sources on BBB and neuroinflammation, which may provide an important implication for dietary guidelines for protein supplementation.

Antihypertensive agents do not prevent blood-brain barrier dysfunction and cognitive deficits in dietary-induced obese mice

BACKGROUND

While vascular risk factors including Western-styled diet and obesity are reported to induce cognitive decline and increase dementia risk, recent reports consistently suggest that compromised integrity of cerebrovascular blood-brain barrier (BBB) may have an important role in neurodegeneration and cognitive deficits. A number of studies report that elevated blood pressure increases the permeability of BBB.

METHODS

In this study, we investigated the effects of antihypertensive agents, candesartan or ursodeoxycholic acid (UDCA), on BBB dysfunction and cognitive decline in wild-type mice maintained on high fat and fructose (HFF) diet for 24 weeks.

RESULTS

In HFF-fed mice, significantly increased body weight with elevated blood pressure, plasma insulin and glucose compared with mice fed with low-fat control chow was observed. Concomitantly, significant disruption of BBB and cognitive decline were evident in the HFF-fed obese mice. Hypertension was completely prevented by the coprovision of candesartan or UDCA in mice maintained on HFF diet, while only candesartan significantly reduced the body weight compared with HFF-fed mice. Nevertheless, BBB dysfunction and cognitive decline remained unaffected by candesartan or UDCA.

CONCLUSIONS

These data conclusively indicate that modulation of blood pressure and/or body weight may not be directly associated with BBB dysfunction and cognitive deficits in Western diet-induced obese mice, and hence antihypertensive agents may not be effective in preventing BBB disruption and cognitive decline. The findings may provide important mechanistical insights to obesity-associated cognitive decline and its therapy.

Antioxidants and Dementia Risk: Consideration through a Cerebrovascular Perspective

A number of natural and chemical compounds that exert anti-oxidative properties are demonstrated to be beneficial for brain and cognitive function, and some are reported to reduce the risk of dementia. However, the detailed mechanisms by which those anti-oxidative compounds show positive effects on cognition and dementia are still unclear. An emerging body of evidence suggests that the integrity of the cerebrovascular blood-brain barrier (BBB) is centrally involved in the onset and progression of cognitive impairment and dementia. While recent studies revealed that some anti-oxidative agents appear to be protective against the disruption of BBB integrity and structure, few studies considered the neuroprotective effects of antioxidants in the context of cerebrovascular integrity. Therefore, in this review, we examine the mechanistic insights of antioxidants as a pleiotropic agent for cognitive impairment and dementia through a cerebrovascular axis by primarily focusing on the current available data from physiological studies. Conclusively, there is a compelling body of evidence that suggest antioxidants may prevent cognitive decline and dementia by protecting the integrity and function of BBB and, indeed, further studies are needed to directly examine these effects in addition to underlying molecular mechanisms.

The effect of short-term exposure to energy-matched diets enriched in fat or sugar on memory, gut microbiota and markers of brain inflammation and plasticity

Short-term exposure to high-energy diets impairs memory but there is little data on the relative contributions of fat and sugar to these deficits or the mechanisms responsible. Here, we investigated how these different macronutrients affect memory, neuroinflammation and neuroplasticity markers and the gut microbiota. Rats were fed matched purified diets for 2weeks; Control, Sugar, Saturated Fatty Acid (SFA) or Polyunsaturated Fatty Acid (PUFA), which varied only in the percentage of energy available from sugar and the amount and type of fat. Rats consuming SFA and Sugar were impaired on hippocampal-dependent place recognition memory compared to Controls and PUFA rats, despite all rats consuming similar amounts of energy. All rats performed comparably on the object recognition task. Hippocampal and hypothalamic inflammatory markers were not substantially affected by the diets and there was no change in the neuroplasticity marker, brain-derived neurotrophic factor. Each of the diets significantly altered the microbial composition in distinct ways. Specifically, the relative abundance of 89 taxa differed significantly between groups with the majority of these changes accounted for by the Clostridiales order and within that, Lachnospiraceae and Ruminococcaceae. These taxa showed a range of macronutrient specific correlations with place memory. In addition, Distance based Linear Models found relationships between memory, inflammation-related hippocampal genes and the gut microbiota. In conclusion, our study shows that the macronutrient profile of the diet is crucial for diet-induced memory deficits and suggests a possible link between diet, the gut microbiota and hippocampal inflammatory genes.

Resolution of non-psychogenic epileptic-like seizures utilizing a vasodilatory and anti-inflammatory dietary intervention

A young female subject with ineffective pharmacological regulation of chronic vasoconstrictive-induced epilectic-like seizures was effectively treated with a dietary regimen targeted to promote vasodilatation and attenuate vascular inflammation. The intervention consisted of complete cessation of caffeinated beverages, supplementation with L-arginine to promote vasodilatation, consumption of foods rich in phytoestrogens, minimization of foods enriched with saturated fatty acids, supplementation with vitamin D concomitant with increased ingestion of dairy milk and supplementation with aged garlic extract.

Pharmacological modulation of dietary lipid-induced cerebral capillary dysfunction: Considerations for reducing risk for Alzheimer's disease

An increasing body of evidence suggests that cerebrovascular dysfunction and microvessel disease precede the evolution of hallmark pathological features that characterise Alzheimer's disease (AD), consistent with a causal association for onset or progression. Recent studies, principally in genetically unmanipulated animal models, suggest that chronic ingestion of diets enriched in saturated fats and cholesterol may compromise blood-brain barrier (BBB) integrity resulting in inappropriate blood-to-brain extravasation of plasma proteins, including lipid macromolecules that may be enriched in amyloid-β (Aβ). Brain parenchymal retention of blood proteins and lipoprotein bound Aβ is associated with heightened neurovascular inflammation, altered redox homeostasis and nitric oxide (NO) metabolism. Therefore, it is a reasonable proposition that lipid-lowering agents may positively modulate BBB integrity and by extension attenuate risk or progression of AD. In addition to their robust lipid lowering properties, reported beneficial effects of lipid-lowering agents were attributed to their pleiotropic properties via modulation of inflammation, oxidative stress, NO and Aβ metabolism. The review is a contemporary consideration of a complex body of literature intended to synthesise focussed consideration of mechanisms central to regulation of BBB function and integrity. Emphasis is given to dietary fat driven significant epidemiological evidence consistent with heightened risk amongst populations consuming greater amounts of saturated fats and cholesterol. In addition, potential neurovascular benefits associated with the use of hypolipidemic statins, probucol and fenofibrate are also presented in the context of lipid-lowering and pleiotropic properties.

Blood-brain barrier dysfunction developed during normal aging is associated with inflammation and loss of tight junctions but not with leukocyte recruitment

Background

Functional loss of blood–brain barrier (BBB) is suggested to be pivotal to pathogenesis and pathology of vascular-based neurodegenerative disorders such as Alzheimer’s disease. We recently reported in wild-type mice maintained on standard diets, progressive deterioration of capillary function with aging concomitant with heightened neuroinflammation. However, the mice used in this study were relatively young (12 months of age) and potential mechanisms for loss of capillary integrity were not investigated per se. The current study therefore extended the previous finding to investigate the effect of aging on BBB integrity in aged mice at 24 months and its potential underlying molecular mechanisms.

Results

Immunomicroscopy analyses confirmed significantly increased capillary permeability with heightened neuroinflammation in naturally aged 24-month old mice compared to young control at 3 months of age. Aged mice showed significant attenuation in the expression of BBB tight junction proteins, occludin-1 and to lesser extent ZO-1 compared to young mice. In addition, TNF-α in cerebral endothelial cells of aged mice was significantly elevated compared to controls and this was associated with heightened peripheral inflammation. The expression of ICAM-1 and VCAM-1 remained unelevated, and no sign of leukocyte recruitment was observed in aged mice.

Conclusion

The BBB breakdown that occurs during ordinary aging is associated with inflammation and disruption of tight junction complex assembly but not through leukocyte trafficking.

Electronic supplementary material

The online version of this article (doi:10.1186/s12979-015-0029-9) contains supplementary material, which is available to authorized users.

Nutritional psychiatry research: an emerging discipline and its intersection with global urbanization, environmental challenges and the evolutionary mismatch

In 21st-century public health, rapid urbanization and mental health disorders are a growing global concern. The relationship between diet, brain function and the risk of mental disorders has been the subject of intense research in recent years. In this review, we examine some of the potential socioeconomic and environmental challenges detracting from the traditional dietary patterns that might otherwise support positive mental health. In the context of urban expansion, climate change, cultural and technological changes and the global industrialization and ultraprocessing of food, findings related to nutrition and mental health are connected to some of the most pressing issues of our time. The research is also of relevance to matters of biophysiological anthropology. We explore some aspects of a potential evolutionary mismatch between our ancestral past (Paleolithic, Neolithic) and the contemporary nutritional environment. Changes related to dietary acid load, advanced glycation end products and microbiota (via dietary choices and cooking practices) may be of relevance to depression, anxiety and other mental disorders. In particular, the results of emerging studies demonstrate the importance of prenatal and early childhood dietary practices within the developmental origins of health and disease concept. There is still much work to be done before these population studies and their mirrored advances in bench research can provide translation to clinical medicine and public health policy. However, the clear message is that in the midst of a looming global epidemic, we ignore nutrition at our peril.

A role for human brain pericytes in neuroinflammation

BACKGROUND

Brain inflammation plays a key role in neurological disease. Although much research has been conducted investigating inflammatory events in animal models, potential differences in human brain versus rodent models makes it imperative that we also study these phenomena in human cells and tissue.

METHODS

Primary human brain cell cultures were generated from biopsy tissue of patients undergoing surgery for drug-resistant epilepsy. Cells were treated with pro-inflammatory compounds IFNγ, TNFα, IL-1β, and LPS, and chemokines IP-10 and MCP-1 were measured by immunocytochemistry, western blot, and qRT-PCR. Microarray analysis was also performed on late passage cultures treated with vehicle or IFNγ and IL-1β.

RESULTS

Early passage human brain cell cultures were a mixture of microglia, astrocytes, fibroblasts and pericytes. Later passage cultures contained proliferating fibroblasts and pericytes only. Under basal culture conditions all cell types showed cytoplasmic NFκB indicating that they were in a non-activated state. Expression of IP-10 and MCP-1 were significantly increased in response to pro-inflammatory stimuli. The two chemokines were expressed in mixed cultures as well as cultures of fibroblasts and pericytes only. The expression of IP-10 and MCP-1 were regulated at the mRNA and protein level, and both were secreted into cell culture media. NFκB nuclear translocation was also detected in response to pro-inflammatory cues (except IFNγ) in all cell types. Microarray analysis of brain pericytes also revealed widespread changes in gene expression in response to the combination of IFNγ and IL-1β treatment including interleukins, chemokines, cellular adhesion molecules and much more.

CONCLUSIONS

Adult human brain cells are sensitive to cytokine challenge. As expected 'classical' brain immune cells, such as microglia and astrocytes, responded to cytokine challenge but of even more interest, brain pericytes also responded to such challenge with a rich repertoire of gene expression. Immune activation of brain pericytes may play an important role in communicating inflammatory signals to and within the brain interior and may also be involved in blood brain barrier (BBB) disruption . Targeting brain pericytes, as well as microglia and astrocytes, may provide novel opportunities for reducing brain inflammation and maintaining BBB function and brain homeostasis in human brain disease.

Long-term probucol therapy continues to suppress markers of neurovascular inflammation in a dietary induced model of cerebral capillary dysfunction

BACKGROUND

Probucol has been shown to prevent cerebral capillary disturbances characterized by blood-to-brain extravasation of plasma derived proteins and neurovascular inflammation in mice maintained on western-styled diets for 12 weeks. However the effect of probucol on capillary integrity in aging models with capillary dysfunction is not known.

METHODS

Wild-type C57BL6 mice were randomized to a low-fat (LF); saturated-fat (SFA); or SFA + Probucol diet for up to12 months of intervention.

RESULTS

Mice fed the LF diet had substantially greater parenchymal abundance of plasma derived IgG and apo B lipoproteins at 12 months, compared to LF mice at 3 months of intervention. Markers of neurovascular inflammation were also greater at 12 months in LF fed mice compared to LF mice at 3 months. The SFA diet exacerbated the aging induced parenchymal abundance of IgG and of apo B lipoproteins and neurovascular inflammation at 12 months. The SFA effects were associated with increased production of intestinal lipoprotein amyloid-β (Aβ). The co-provision of probucol with the SFA completely abolished heightened inflammation at 12 months. Probucol attenuated SFA-induced capillary permeability but had only a modest inhibitory effect on parenchymal retention of apoB lipoproteins. The improvements in markers of inflammation and capillary integrity because of probucol correlated with enterocytic genesis of chylomicron Aβ.

CONCLUSION

In this long-term feeding study, probucol profoundly suppressed dietary SFA induced disturbances in capillary integrity but had a more modest effect on age-associated changes.