Effect of endotoxin on expression of TNF receptors and transport of TNF-alpha at the blood-brain barrier of the rat

Potential of Natural Phenolic Compounds against Doxorubicin-Induced Chemobrain: Biological and Molecular Mechanisms Involved

Chemotherapy-induced cognitive impairment or "chemobrain" is a prevalent long-term complication of chemotherapy and one of the more devastating. Most of the studies performed so far to identify the cognitive dysfunctions induced by antineoplastic chemotherapies have been focused on treatment with anthracyclines, frequently administered to breast cancer patients, a population that, after treatment, shows a high possibility of long survival and, consequently, of chemobrain development. In the last few years, different possible strategies have been explored to prevent or reduce chemobrain induced by the anthracycline doxorubicin (DOX), known to promote oxidative stress and inflammation, which have been strongly implicated in the development of this brain dysfunction. Here, we have critically analyzed the results of the preclinical studies from the last few years that have evaluated the potential of phenolic compounds (PheCs), a large class of natural products able to exert powerful antioxidant and anti-inflammatory activities, in inhibiting DOX-induced chemobrain. Several PheCs belonging to different classes have been shown to be able to revert DOX-induced brain morphological damages and deficits associated with learning, memory, and exploratory behavior. We have analyzed the biological and molecular mechanisms implicated and suggested possible future perspectives in this research area.

The Relevance of Animal Models of Social Isolation and Social Motivation for Understanding Schizophrenia: Review and Future Directions

BACKGROUND AND HYPOTHESES

Social dysfunction in schizophrenia includes symptoms of withdrawal and deficits in social skills, social cognition, and social motivation. Based on the course of illness, with social withdrawal occurring prior to psychosis onset, it is likely that the severity of social withdrawal/isolation contributes to schizophrenia neuropathology.

STUDY DESIGN

We review the current literature on social isolation in rodent models and provide a conceptual framework for its relationship to social withdrawal and neural circuit dysfunction in schizophrenia. We next review preclinical tasks of social behavior used in schizophrenia-relevant models and discuss strengths and limitations of existing approaches. Lastly, we consider new effort-based tasks of social motivation and their potential for translational studies in schizophrenia.

STUDY RESULTS

Social isolation rearing in rats produces profound differences in behavior, pharmacologic sensitivity, and neurochemistry compared to socially reared rats. Rodent models relevant to schizophrenia exhibit deficits in social behavior as measured by social interaction and social preference tests. Newer tasks of effort-based social motivation are being developed in rodents to better model social motivation deficits in neuropsychiatric disorders.

CONCLUSIONS

While experimenter-imposed social isolation provides a viable experimental model for understanding some biological mechanisms linking social dysfunction to clinical and neural pathology in schizophrenia, it bypasses critical antecedents to social isolation in schizophrenia, notably deficits in social reward and social motivation. Recent efforts at modeling social motivation using effort-based tasks in rodents have the potential to quantify these antecedents, identify models (eg, developmental, genetic) that produce deficits, and advance pharmacological treatments for social motivation.

Chemotherapy-Mediated Neuronal Aberration

Chemotherapy is a life-sustaining therapeutic option for cancer patients. Despite the advancement of several modern therapies, such as immunotherapy, gene therapy, etc., chemotherapy remains the first-line therapy for most cancer patients. Along with its anti-cancerous effect, chemotherapy exhibits several detrimental consequences that restrict its efficacy and long-term utilization. Moreover, it effectively hampers the quality of life of cancer patients. Cancer patients receiving chemotherapeutic drugs suffer from neurological dysfunction, referred to as chemobrain, that includes cognitive and memory dysfunction and deficits in learning, reasoning, and concentration ability. Chemotherapy exhibits neurotoxicity by damaging the DNA in neurons by interfering with the DNA repair system and antioxidant machinery. In addition, chemotherapy also provokes inflammation by inducing the release of various pro-inflammatory cytokines, including NF-kB, IL-1β, IL-6, and TNF-α. The chemotherapy-mediated inflammation contributes to chemobrain in cancer patients. These inflammatory cytokines modulate several growth signaling pathways and reactive oxygen species homeostasis leading to systemic inflammation in the body. This review is an effort to summarize the available information which discusses the role of chemotherapy-induced inflammation in chemobrain and how it impacts different aspects of therapeutic outcome and the overall quality of life of the patient. Further, this article also discusses the potential of herbal-based remedies to overcome chemotherapy-mediated neuronal toxicity as well as to improve the quality of life of cancer patients.

Vitamin D3 exerts immunomodulatory and memory improving properties in rats with lipopolysaccharide-induced inflammation

INTRODUCTION

Vitamin D is a fat-soluble secosteroid, its primary function being regulation of calcium-phosphate homeostasis and maintenance of bone integrity and mineralization. Recently, pleotropic effects of this vitamin have been recognized, including an immunomodulatory role and involvement in normal brain development and functioning.

A microengineered Brain-Chip to model neuroinflammation in humans

Species differences in brain and blood-brain barrier (BBB) biology hamper the translation of findings from animal models to humans, impeding the development of therapeutics for brain diseases. Here, we present a human organotypic microphysiological system (MPS) that includes endothelial-like cells, pericytes, glia, and cortical neurons and maintains BBB permeability at in vivo relevant levels. This human Brain-Chip engineered to recapitulate critical aspects of the complex interactions that mediate neuroinflammation and demonstrates significant improvements in clinical mimicry compared to previously reported similar MPS. In comparison to Transwell culture, the transcriptomic profiling of the Brain-Chip displayed significantly advanced similarity to the human adult cortex and enrichment in key neurobiological pathways. Exposure to TNF-α recreated the anticipated inflammatory environment shown by glia activation, increased release of proinflammatory cytokines, and compromised barrier permeability. We report the development of a robust brain MPS for mechanistic understanding of cell-cell interactions and BBB function during neuroinflammation.

Succinum extracts inhibit microglial-derived neuroinflammation and depressive-like behaviors

Microglia are emerging as important targets for the treatment of neuropsychiatric disorders. The phagocytic microglial phenotype and the resulting neuroinflammation lead to synaptic loss and neuronal cell death. To explore potential candidates that inhibit microglial hyperactivation, we first investigated ten candidate extracts of traditional Chinese medicine (TCM) using lipopolysaccharide (LPS)-stimulated BV2 microglial cells. Among the candidates, Pinus spp. succinum extract (PSE) was superior; thus, we further investigated its pharmacological activity and underlying mechanisms both in vitro and in vivo. Pretreatment with PSE (10, 20, and 40 μg/ml) attenuated the increases in inflammatory factors (nitric oxide and tumor necrosis factor-α), translocation of nuclear factor-kappa B (NF-κB), and phenotypic transformations (phagocytic and migratory) in a dose-dependent manner. These inhibitory effects of PSE on microglia were supported by its regulatory effects on the CX3C chemokine receptor 1 (CX3CR1)/nuclear factor erythroid-2-related factor 2 (Nrf2) pathway. In particular, intragastric administration of PSE (100 mg/kg) considerably improved sickness, anxiety, and depressive-like behaviors in mice subjected to chronic restraint stress (CRS). Our results suggest that PSE has strong antineuroinflammatory and antidepressant properties, and the underlying mechanisms may involve not only the regulation of NF-κB translocation but also the normalization of the CX3CR1/Nrf2 pathway.

The Impact of Systemic Inflammation on Alzheimer's Disease Pathology

Alzheimer’s disease (AD) is a devastating age-related neurodegenerative disorder with an alarming increasing prevalence. Except for the recently FDA-approved Aducanumab of which the therapeutic effect is not yet conclusively proven, only symptomatic medication that is effective for some AD patients is available. In order to be able to design more rational and effective treatments, our understanding of the mechanisms behind the pathogenesis and progression of AD urgently needs to be improved. Over the last years, it became increasingly clear that peripheral inflammation is one of the detrimental factors that can contribute to the disease. Here, we discuss the current understanding of how systemic and intestinal (referred to as the gut-brain axis) inflammatory processes may affect brain pathology, with a specific focus on AD. Moreover, we give a comprehensive overview of the different preclinical as well as clinical studies that link peripheral Inflammation to AD initiation and progression. Altogether, this review broadens our understanding of the mechanisms behind AD pathology and may help in the rational design of further research aiming to identify novel therapeutic targets.

Parkinson's Disease and the Metal-Microbiome-Gut-Brain Axis: A Systems Toxicology Approach

Parkinson's Disease (PD) is a neurodegenerative disease, leading to motor and non-motor complications. Autonomic alterations, including gastrointestinal symptoms, precede motor defects and act as early warning signs. Chronic exposure to dietary, environmental heavy metals impacts the gastrointestinal system and host-associated microbiome, eventually affecting the central nervous system. The correlation between dysbiosis and PD suggests a functional and bidirectional communication between the gut and the brain. The bioaccumulation of metals promotes stress mechanisms by increasing reactive oxygen species, likely altering the bidirectional gut-brain link. To better understand the differing molecular mechanisms underlying PD, integrative modeling approaches are necessary to connect multifactorial perturbations in this heterogeneous disorder. By exploring the effects of gut microbiota modulation on dietary heavy metal exposure in relation to PD onset, the modification of the host-associated microbiome to mitigate neurological stress may be a future treatment option against neurodegeneration through bioremediation. The progressive movement towards a systems toxicology framework for precision medicine can uncover molecular mechanisms underlying PD onset such as metal regulation and microbial community interactions by developing predictive models to better understand PD etiology to identify options for novel treatments and beyond. Several methodologies recently addressed the complexity of this interaction from different perspectives; however, to date, a comprehensive review of these approaches is still lacking. Therefore, our main aim through this manuscript is to fill this gap in the scientific literature by reviewing recently published papers to address the surrounding questions regarding the underlying molecular mechanisms between metals, microbiota, and the gut-brain-axis, as well as the regulation of this system to prevent neurodegeneration.

Minocycline attenuation of rat corpus callosum abnormality mediated by low-dose lipopolysaccharide-induced microglia activation

Background

Microglia are resident innate immune cells in the brain, and activation of these myeloid cells results in secretion of a variety of pro-inflammatory molecules, leading to the development of neurodegenerative disorders. Lipopolysaccharide (LPS) is a widely used experimental stimulant in microglia activation. We have previously shown that LPS produced microglia activation and evoked detectable functional abnormalities in rat corpus callosum (CC) in vitro. Here, we further validated the effects of low-dose LPS-induced microglia activation and resultant white matter abnormality in the CC in an animal model and examined its attenuation by an anti-inflammatory agent minocycline.

Methods

Twenty-four SD rats were divided randomly into three groups and intra-peritoneally injected daily with saline, LPS, and LPS + minocycline, respectively. All animals were subject to MRI tests 6 days post-injection. The animals were then sacrificed to harvest the CC tissues for electrophysiology, western blotting, and immunocytochemistry. One-way ANOVA with Tukey’s post-test of all pair of columns was employed statistical analyses.

Results

Systemic administration of LPS produced microglial activation in the CC as illustrated by Iba-1 immunofluorescent staining. We observed that a large number of Iba-1-positive microglial cells were hyper-ramified with hypertrophic somata or even amoeba like in the LPS-treated animals, and such changes were significantly reduced by co-administration of minocycline. Electrophysiological recordings of axonal compound action potential (CAP) in the brain slices contained the CC revealed an impairment on the CC functionality as detected by a reduction in CAP magnitude. Such an impairment was supported by a reduction of fast axonal transportation evidenced by β-amyloid precursor protein accumulation. These alterations were attenuated by minocycline, demonstrating minocycline reduction of microglia-mediated interruption of white matter integrity and function in the CC.

Conclusions

Systemic administration of LPS produced microglia activation in the CC and resultant functional abnormalities that were attenuated by an anti-inflammatory agent minocycline.

Anti-Inflammatory Therapies for Treatment of Inflammation-Related Preterm Brain Injury

Despite the prevalence of preterm brain injury, there are no established neuroprotective strategies to prevent or alleviate mild-to-moderate inflammation-related brain injury. Perinatal infection and inflammation have been shown to trigger acute neuroinflammation, including proinflammatory cytokine release and gliosis, which are associated with acute and chronic disturbances in brain cell survival and maturation. These findings suggest the hypothesis that the inhibition of peripheral immune responses following infection or nonspecific inflammation may be a therapeutic strategy to reduce the associated brain injury and neurobehavioral deficits. This review provides an overview of the neonatal immunity, neuroinflammation, and mechanisms of inflammation-related brain injury in preterm infants and explores the safety and efficacy of anti-inflammatory agents as potentially neurotherapeutics.

Oxidative Stress-Related Mechanisms in Schizophrenia Pathogenesis and New Treatment Perspectives

Schizophrenia is recognized to be a highly heterogeneous disease at various levels, from genetics to clinical manifestations and treatment sensitivity. This heterogeneity is also reflected in the variety of oxidative stress-related mechanisms contributing to the phenotypic realization and manifestation of schizophrenia. At the molecular level, these mechanisms are supposed to include genetic causes that increase the susceptibility of individuals to oxidative stress and lead to gene expression dysregulation caused by abnormal regulation of redox-sensitive transcriptional factors, noncoding RNAs, and epigenetic mechanisms favored by environmental insults. These changes form the basis of the prooxidant state and lead to altered redox signaling related to glutathione deficiency and impaired expression and function of redox-sensitive transcriptional factors (Nrf2, NF-κB, FoxO, etc.). At the cellular level, these changes lead to mitochondrial dysfunction and metabolic abnormalities that contribute to aberrant neuronal development, abnormal myelination, neurotransmitter anomalies, and dysfunction of parvalbumin-positive interneurons. Immune dysfunction also contributes to redox imbalance. At the whole-organism level, all these mechanisms ultimately contribute to the manifestation and development of schizophrenia. In this review, we consider oxidative stress-related mechanisms and new treatment perspectives associated with the correction of redox imbalance in schizophrenia. We suggest that not only antioxidants but also redox-regulated transcription factor-targeting drugs (including Nrf2 and FoxO activators or NF-κB inhibitors) have great promise in schizophrenia. But it is necessary to develop the stratification criteria of schizophrenia patients based on oxidative stress-related markers for the administration of redox-correcting treatment.

Cytokine Imbalance in Schizophrenia. From Research to Clinic: Potential Implications for Treatment

Cytokines are one of the most important components of the immune system. They orchestrate the brain's response to infectious and other exogenous insults and are crucial mediators of the cross-talk between the nervous and immune systems. Epidemiological studies have demonstrated that severe infections and autoimmune disorders, in addition to genetic predisposition, are risk factors for schizophrenia. Furthermore, maternal infection during pregnancy appears to increase the risk of schizophrenia, and proinflammatory cytokines may be negatively involved in the neurodevelopmental process. A cytokine imbalance has been described in the blood and cerebrospinal fluid of schizophrenia patients, particularly in the T helper type 1 [Th1] and type 2 [Th2] cytokines, albeit the results of such studies appear to be contradictory. Chronic stress, likewise, appears to contribute to a lasting proinflammatory state and likely also promotes the disorder. The aim of this mini-review is to investigate the roles of different cytokines in the pathophysiology of schizophrenia and define how cytokines may represent key molecular targets to regulate for the prevention and treatment of schizophrenia. How current antipsychotic drugs impact cytokine networks is also evaluated. In this context, we propose to change the focus of schizophrenia from a traditionally defined brain disorder, to one that is substantially impacted by the periphery and immune system.

Glia-Driven Neuroinflammation and Systemic Inflammation in Alzheimer's Disease

The neuroinflammatory hypothesis of Alzheimer's disease (AD) was proposed more than 30 years ago. The involvement of the two main types of glial cells microglia and astrocytes, in neuroinflammation, was suggested early on. In this review, we highlight that the exact contributions of reactive glia to AD pathogenesis remain difficult to define, likely due to the heterogeneity of glia populations and alterations in their activation states through the stages of AD progression. In the case of microglia, it is becoming apparent that both beneficially and adversely activated cell populations can be identified at various stages of AD, which could be selectively targeted to either limit their damaging actions or enhance beneficial functions. In the case of astrocytes, less information is available about potential subpopulations of reactive cells; it also remains elusive whether astrocytes contribute to the neuropathology of AD by mainly gaining neurotoxic functions or losing their ability to support neurons due to astrocyte damage. We identify L-type calcium channel blocker, nimodipine, as a candidate drug for AD, which potentially targets both astrocytes and microglia. It has already shown consistent beneficial effects in basic experimental and clinical studies. We also highlight the recent evidence linking peripheral inflammation and neuroinflammation. Several chronic systemic inflammatory diseases, such as obesity, type 2 diabetes mellitus, and periodontitis, can cause immune priming or adverse activation of glia, thus exacerbating neuroinflammation and increasing risk or facilitating the progression of AD. Therefore, reducing peripheral inflammation is a potentially effective strategy for lowering AD prevalence.

Transport of Extracellular Vesicles across the Blood-Brain Barrier: Brain Pharmacokinetics and Effects of Inflammation

Extracellular vesicles can cross the blood–brain barrier (BBB), but little is known about passage. Here, we used multiple-time regression analysis to examine the ability of 10 exosome populations derived from mouse, human, cancerous, and non-cancerous cell lines to cross the BBB. All crossed the BBB, but rates varied over 10-fold. Lipopolysaccharide (LPS), an activator of the innate immune system, enhanced uptake independently of BBB disruption for six exosomes and decreased uptake for one. Wheatgerm agglutinin (WGA) modulated transport of five exosome populations, suggesting passage by adsorptive transcytosis. Mannose 6-phosphate inhibited uptake of J774A.1, demonstrating that its BBB transporter is the mannose 6-phosphate receptor. Uptake rates, patterns, and effects of LPS or WGA were not predicted by exosome source (mouse vs. human) or cancer status of the cell lines. The cell surface proteins CD46, AVβ6, AVβ3, and ICAM-1 were variably expressed but not predictive of transport rate nor responses to LPS or WGA. A brain-to-blood efflux mechanism variably affected CNS retention and explains how CNS-derived exosomes enter blood. In summary, all exosomes tested here readily crossed the BBB, but at varying rates and by a variety of vesicular-mediated mechanisms involving specific transporters, adsorptive transcytosis, and a brain-to-blood efflux system.

Doxorubicin and cisplatin induced cognitive impairment: The possible mechanisms and interventions

Chemotherapy has significantly increased the number of cancer survivors. However, chemotherapy itself carries various adverse effects that limit the efficacy of treatment and quality of life of the cancer patients. Most patients who have received chemotherapy report some cognitive deficit characterized by dysfunction in memory, learning, concentration, and reasoning. The phenomenon of cognitive decline developed from chemotherapy treatment is referred to as chemotherapy-induced cognitive impairment (CICI) or chemobrain. The two most common cancers occurring worldwide are lung and breast cancer. The predominant chemotherapeutic drugs used to treat lung and breast cancer are doxorubicin and cisplatin. There is evidence to suggest that both drugs potentially induce chemobrain. The evidence around the proposed pathogenesis of chemobrain caused by these two drugs is inconsistent. Understanding the underlying mechanisms involved in the development of chemobrain would aid in the prevention or treatment of the adverse effects of chemotherapy on brain. This review will summarize and discuss controversial findings and possible mechanisms involved in the development of chemobrain and the interventions which could limit it from in vitro, in vivo, and clinical studies.

Lipid-Binding Proteins in Brain Health and Disease

A proper lipid management is paramount for a healthy brain. Lipid homeostasis alterations are known to be causative or risk factors for many neurodegenerative diseases, or key elements in the recovery from nervous system injuries of different etiology. In addition to lipid biogenesis and catabolism, non-enzymatic lipid-binding proteins play an important role in brain function and maintenance through aging. Among these types of lipoproteins, apolipoprotein E has received much attention due to the relationship of particular alleles of its gene with the risk and progression of Alzheimer's disease. However, other lipid-binding proteins whose role in lipid homeostasis and control are less known need to be brought to the attention of both researchers and clinicians. The aim of this review is to cover the knowledge of lipid-managing proteins in the brain, with particular attention to new candidates to be relevant for brain function and health.

Gut Inflammation in Association With Pathogenesis of Parkinson's Disease

Parkinson’s disease (PD) is a neurodegenerative disease that is generally thought to be caused by multiple factors, including environmental and genetic factors. Emerging evidence suggests that intestinal disturbances, such as constipation, are common non-motor symptoms of PD. Gut inflammation may be closely associated with pathogenesis in PD. This review aims to discuss the cross-talk between gut inflammation and PD pathology initiation and progression. Firstly, we will highlight the studies demonstrating how gut inflammation is related to PD. Secondly, we will analyze how gut inflammation spreads from the gastro-intestine to the brain. Here, we will mainly discuss the neural pathway of pathologic α-syn and the systemic inflammatory routes. Thereafter, we will address how alterations in the brain subsequently lead to dopaminergic neuron degeneration, in which oxidative stress, glutamate excitotoxicity, T cell driven inflammation and cyclooxygenase-2 (COX-2) are involved. We conclude a model of PD triggered by gut inflammation, which provides a new angle to understand the mechanisms of the disease.

Immune mechanisms of stress susceptibility and resilience: Lessons from animal models

Stress has an impact on the brain and the body. A growing literature demonstrates that feedback between the peripheral immune system and the brain contributes to individual differences in the behavioral response to stress. Here we examine preclinical literature to demonstrate a holistic vision of risk and resilience to stress. We identify a variety of cellular, cytokine and molecular mechanisms in adult animals that act in concert to produce a stress susceptible individual response. We discuss how cross talk between immune cells in the brain and in the periphery act together to increase permeability across the blood brain barrier or block it, resulting in susceptible or stress resilient phenotype. These preclinical studies have importance for understanding how individual differences in the immune response to stress may be contributing to mood related disorders such as depression, anxiety and posttraumatic stress disorders.

Omi/HtrA2 Protease Associated Cell Apoptosis Participates in Blood-Brain Barrier Dysfunction

Background: Omi/HtrA2 is a proapoptotic mitochondrial serine protease involved in caspase-dependent cell apoptosis, translocating from mitochondria to the cytosol after an apoptotic insult. Our previous study indicated pre-treatment with UCF-101, a specific inhibitor of Omi/HtrA2, could significantly reduce neuronal apoptosis and attenuate sepsis-induced cognitive dysfunction. Various hypotheses involving blood-brain-barrier (BBB) disruption have been proposed to account for sepsis-associated encephalopathy (SAE). Here, we attempted to explore whether interference of Omi/HtrA2 by RNA interference or UCF-101 pre-treatment can improve sepsis-induced disruption of BBB using human cerebral microvascular endothelial cell line (hCMEC/D3) in vitro and if so, to explore mechanisms involved Omi/HtrA2 protease mediates BBB disruption in SAE.

Methods: hCMEC/D3 cell monolayers were intervened by different concentrations of LPS (0–50 μg/mL) over experimental period. Pharmacological or gene interventions (by silencing RNA of Omi/HtrA2) were used to study molecular mechanisms involved in sepsis-associated Omi/HtrA2 translocation, cell apoptosis and BBB dysfunction. BBB function was assessed by trans-endothelial electrical resistance (TEER) and permeability to labeled dextrans (FITC-4kDa). Tight junction (TJ) integrity was assessed by immunofluorescence, western blotting and transmission electron microscopic (TEM) analyses. Apoptosis was determined using flow cytometry and TUNEL assay. Mitochondrial membrane potential (MMP) and oxidative stress were also investigated.

Results: LPS affects hCMEC/D3 TJ permeability in a concentration- and time-dependent manner. LPS intervention resulted in a significant disruption of BBB, as manifested by decreased TEER (by ~26%) and a parallel increased paracellular permeability to FITC- (4kDa) dextrans through hCMEC/D3 monolayers. The inhibition of Omi/HtrA2 by UCF-101 or Omi/HtrA2 shRNA reduced LPS-induced brain endothelial cell apoptosis, and resulted in significant improvement on LPS-induced BBB disruption as well as decreased occludin, claudin-5 and ZO-1 expressions. Omi/HtrA2 manipulated endothelial cell apoptosis by shifting into cytosol and inducing X-linked inhibitor of apoptosis protein (XIAP) degradation. UCF-101 administration or Omi/HtrA2 shRNA intervention did attenuate the degradation of XIAP, Poly ADP-ribose polymerase (PARP) cleavage, and caspase-3 cleavage. However, only UCF-101 partly prevented the mobilization of Omi/HtrA2 from the mitochondria to the cytosol after LPS intervention. That abrogation of Omi/HtrA2 by UCF-101 or Omi/HtrA2 shRNA resulted in a significant improvement on LPS-induced decrease of MMP. Oxidative stress was significantly increased in the LPS treated group compared to the control or NC-shRNA group. However, abrogation of Omi/HtrA2 by UCF-101 or Omi/HtrA2 shRNA did not significantly improve oxidative injury.

Conclusions: Our study indicated an important role of Omi/HtrA2 in manipulating LPS-induced cell apoptosis and BBB integrity by translocating from mitochondria into cytosol in brain endothelial cells. Omi/HtrA2 induced mitochondrial pathway apoptosis, which involves inhibition of an important antiapoptotic protein XIAP and influence on MMP. Therapeutic methods that inhibit Omi/HtrA2 function may provide a novel therapeutic measure to septic encephalopathy.

Leaky brain in neurological and psychiatric disorders: Drivers and consequences

BACKGROUND

The blood-brain barrier acts as a highly regulated interface; its dysfunction may exacerbate, and perhaps initiate, neurological and neuropsychiatric disorders.

METHODS

In this narrative review, focussing on redox, inflammatory and mitochondrial pathways and their effects on the blood-brain barrier, a model is proposed detailing mechanisms which might explain how increases in blood-brain barrier permeability occur and can be maintained with increasing inflammatory and oxidative and nitrosative stress being the initial drivers.

RESULTS

Peripheral inflammation, which is causatively implicated in the pathogenesis of major psychiatric disorders, is associated with elevated peripheral pro-inflammatory cytokines, which in turn cause increased blood-brain barrier permeability. Reactive oxygen species, such as superoxide radicals and hydrogen peroxide, and reactive nitrogen species, such as nitric oxide and peroxynitrite, play essential roles in normal brain capillary endothelial cell functioning; however, chronically elevated oxidative and nitrosative stress can lead to mitochondrial dysfunction and damage to the blood-brain barrier. Activated microglia, redox control of which is mediated by nitric oxide synthases and nicotinamide adenine dinucleotide phosphate (NADPH) oxidases, secrete neurotoxic molecules such as reactive oxygen species, nitric oxide, prostaglandin, cyclooxygenase-2, quinolinic acid, several chemokines (including monocyte chemoattractant protein-1 [MCP-1], C-X-C motif chemokine ligand 1 [CXCL-1] and macrophage inflammatory protein 1α [MIP-1α]) and the pro-inflammatory cytokines interleukin-6, tumour necrosis factor-α and interleukin-1β, which can exert a detrimental effect on blood-brain barrier integrity and function. Similarly, reactive astrocytes produce neurotoxic molecules such as prostaglandin E2 and pro-inflammatory cytokines, which can cause a 'leaky brain'.

CONCLUSION

Chronic inflammatory and oxidative and nitrosative stress is associated with the development of a 'leaky gut'. The following evidence-based approaches, which address the leaky gut and blood-brain barrier dysfunction, are suggested as potential therapeutic interventions for neurological and neuropsychiatric disorders: melatonin, statins, probiotics containing Bifidobacteria and Lactobacilli, N-acetylcysteine, and prebiotics containing fructo-oligosaccharides and galacto-oligosaccharides.

Effects of Cyclophosphamide and/or Doxorubicin in a Murine Model of Postchemotherapy Cognitive Impairment

Postchemotherapy cognitive impairment, or PCCI, is a common complaint, particularly among breast cancer patients. However, the exact nature of PCCI appears complex. To model the human condition, ovariectomized C57BL/6J mice were treated intravenous weekly for 4 weeks with saline, 2 mg/kg doxorubicin (DOX), 50 mg/kg cyclophosphamide (CYP), or DOX + CYP. For the subsequent 10 weeks, mice were assessed on several behavioral tests, including those measuring spatial learning and memory. After sacrifice, hippocampal spine density and morphology in the dentate gyrus, CA1, and CA3 regions were measured. Additionally, hippocampal levels of total glutathione, glutathione disulfide, MnSOD, CuZnSOD, and cytokines were measured. Body weight decreased in all groups during treatment, but recovered post-treatment. Most behaviors were unaffected by drug treatment: Open field activity, motor coordination, grip strength, water maze and Barnes maze performance, buried food test performance, and novel object and object location recognition tests. There were some significant effects of CYP and DOX + CYP treatment during the initial test of home cage behavior, but these did not persist into the second and third test times. Density of stubby spines, but not mushroom or thin spines, in the dentate gyrus was significantly decreased in the DOX, CYP, and DOX + CYP treatment groups. There were no significant effects in the CA1 or CA3 regions. CuZnSOD levels were significantly increased in DOX + CYP-treated mice; other hippocampal antioxidant levels were unaffected. Most cytokines showed no treatment-related effects, but IL-1β, IL-6, and IL-12 were slightly reduced in mice treated with DOX + CYP. Although the animal model, route of exposure, and DOX and CYP doses used here were reflective of human exposure, there were only sporadic effects due to chemotherapeutic treatment.

Protective effects of curcumin against doxorubicin-induced toxicity and resistance: A review

Doxorubicin (DOX)-induced toxicity and resistance are major obstacles in chemotherapeutic approaches. Despite effective in the treatment of numerous malignancies, some clinicians have voiced concern that DOX has the potential to cause debilitating consequences in organ tissues, especially the heart. The mechanisms of toxicity and resistance are respectively related to induction of reactive oxygen species (ROS) and up-regulation of ATP-binding cassette (ABC) transporter. Curcumin (CUR) with several biological and pharmacological properties is expected to restore DOX-mediated impairments to tissues. This review is intended to address the current knowledge on DOX adverse effects and CUR protective actions in the heart, kidneys, liver, brain, and reproductive organs. Coadministration of CUR and DOX is capable of ameliorating DOX toxicity pertained to antioxidant, apoptosis, autophagy, and mitochondrial permeability.

The blood-brain barrier in systemic inflammation

The blood-brain barrier (BBB) plays a key role in maintaining the specialized microenvironment of the central nervous system (CNS), and enabling communication with the systemic compartment. BBB changes occur in several CNS pathologies. Here, we review disruptive and non-disruptive BBB changes in systemic infections and other forms of systemic inflammation, and how these changes may affect CNS function in health and disease. We first describe the structure and function of the BBB, and outline the techniques used to study the BBB in vitro, and in animal and human settings. We then summarise the evidence from a range of models linking BBB changes with systemic inflammation, and the underlying mechanisms. The clinical relevance of these BBB changes during systemic inflammation are discussed in the context of clinically-apparent syndromes such as sickness behaviour, delirium, and septic encephalopathy, as well as neurological conditions such as Alzheimer's disease and multiple sclerosis. We review emerging evidence for two novel concepts: (1) a heightened sensitivity of the diseased, versus healthy, BBB to systemic inflammation, and (2) the contribution of BBB changes induced by systemic inflammation to progression of the primary disease process.

Metabolic consequences of inflammatory disruption of the blood-brain barrier in an organ-on-chip model of the human neurovascular unit

Background

Understanding blood-brain barrier responses to inflammatory stimulation (such as lipopolysaccharide mimicking a systemic infection or a cytokine cocktail that could be the result of local or systemic inflammation) is essential to understanding the effect of inflammatory stimulation on the brain. It is through the filter of the blood-brain barrier that the brain responds to outside influences, and the blood-brain barrier is a critical point of failure in neuroinflammation. It is important to note that this interaction is not a static response, but one that evolves over time. While current models have provided invaluable information regarding the interaction between cytokine stimulation, the blood-brain barrier, and the brain, these approaches—whether in vivo or in vitro—have often been only snapshots of this complex web of interactions.

Methods

We utilize new advances in microfluidics, organs-on-chips, and metabolomics to examine the complex relationship of inflammation and its effects on blood-brain barrier function ex vivo and the metabolic consequences of these responses and repair mechanisms. In this study, we pair a novel dual-chamber, organ-on-chip microfluidic device, the NeuroVascular Unit, with small-volume cytokine detection and mass spectrometry analysis to investigate how the blood-brain barrier responds to two different but overlapping drivers of neuroinflammation, lipopolysaccharide and a cytokine cocktail of IL-1β, TNF-α, and MCP1,2.

Results

In this study, we show that (1) during initial exposure to lipopolysaccharide, the blood-brain barrier is compromised as expected, with increased diffusion and reduced presence of tight junctions, but that over time, the barrier is capable of at least partial recovery; (2) a cytokine cocktail also contributes to a loss of barrier function; (3) from this time-dependent cytokine activation, metabolic signature profiles can be obtained for both the brain and vascular sides of the blood-brain barrier model; and (4) collectively, we can use metabolite analysis to identify critical pathways in inflammatory response.

Conclusions

Taken together, these findings present new data that allow us to study the initial effects of inflammatory stimulation on blood-brain barrier disruption, cytokine activation, and metabolic pathway changes that drive the response and recovery of the barrier during continued inflammatory exposure.

Electronic supplementary material

The online version of this article (doi:10.1186/s12974-016-0760-y) contains supplementary material, which is available to authorized users.

Clearing the fog: a review of the effects of dietary omega-3 fatty acids and added sugars on chemotherapy-induced cognitive deficits

Cancer treatments such as chemotherapy have been an important part of extending survival in women diagnosed with breast cancer. However, chemotherapy can cause potentially toxic side effects in the brain that impair memory, verbal fluency, and processing speed in up to 30% of women treated. Women report that post-chemotherapy cognitive deficits negatively impact quality of life and may last up to ten years after treatment. Mechanisms underlying these cognitive impairments are not fully understood, but emerging evidence suggests that chemotherapy induces structural changes in the brain, produces neuroinflammation, and reduces adult hippocampal neurogenesis. Dietary approaches that modify inflammation and neurogenesis are promising strategies for reducing chemotherapy-induced cognitive deficits in breast cancer survivors. In this review, we describe the cognitive and neuronal side effects associated with commonly used chemotherapy treatments for breast cancer, and we focus on the often opposing actions of omega-3 fatty acids and added sugars on cognitive function, neuroinflammation, and adult hippocampal neurogenesis. Omega-3 fatty acids administered concurrently with doxorubicin chemotherapy have been shown to prevent depressive-like behaviors and reduce neuroinflammation, oxidative stress, and neural apoptosis in rodent models. In contrast, diets high in added sugars may interact with n-3 FAs to diminish their anti-inflammatory activity or act independently to increase neuroinflammation, reduce adult hippocampal neurogenesis, and promote cognitive deficits. We propose that a diet rich in long-chain, marine-derived omega-3 fatty acids and low in added sugars may be an ideal pattern for preventing or alleviating neuroinflammation and oxidative stress, thereby protecting neurons from the toxic effects of chemotherapy. Research testing this hypothesis could lead to the identification of modifiable dietary choices to reduce the long-term impact of chemotherapy on the cognitive functions that are important to quality of life in breast cancer survivors.

Inflammation and Elevation of Interleukin-12p40 in Patients with Schizophrenia

Schizophrenia is a serious mental illness with chronic symptoms and significant impairment in psychosocial functioning, which suggests that it likely has neurodegenerative characteristics. Inflammatory markers such as pro-inflammatory cytokines are well-known etiological contributors for psychiatric disorders, including schizophrenia. Although, the role of inflammation in schizophrenia is becoming evident, the number of studies in this area is relatively scarce, especially in Lebanon, and increased procedural thoroughness is needed. Cytokines play a key role in the activation of the immune system and strongly influence neurotransmission. Previous investigation of plasma levels showed dysregulation of interleukin (IL)-12. However, genotypical variations of this interleukin have not been investigated for patients with schizophrenia yet. Thus, in this paper, we aimed to compute and assess IL-12p40 levels in the sera of individuals with schizophrenia from different provinces in Lebanon and compare it to controls. Healthy subjects comprised 60 individuals with a male/female (M/F) ratio of 31/29, whereas patients with schizophrenia consisted of 63 subjects with an M/F ratio of 30/33. The mean age for healthy controls was 30 years, whereas that for patients with schizophrenia was 35 years. A standardized enzyme-linked immunosorbent assay (ELISA) technique was used to measure the concentration of IL-12p40 in all collected sera (n = 123). The mean IL-12p40 levels in patients with schizophrenia were significantly higher than in healthy controls (p = 0.002). Healthy females had a significantly higher concentration of IL-12p40 than healthy males (p = 0.009). Female patients with schizophrenia had significantly higher concentrations of IL-12p40 than their male counterparts (p < 0.001), healthy females (p = 0.018), and healthy males (p < 0.001), respectively. Male patients with schizophrenia had significantly higher concentrations of IL-12p40 than healthy males (p = 0.023). The study's results suggest that IL-12p40 has a putative role as a potential marker in schizophrenia and that its elevation may participate in its pathogenesis. IL-12p40 may be included in a panel to be evaluated in the sera of patients with schizophrenia and an appreciation of its independent function is important for improving our understanding of both protective and pathogenic immune responses. Future research should aim to assess this interleukin and understand its role in other mental illnesses that share a similar etiology to schizophrenia.

Tumor necrosis factor-alpha - potential target for neuroprotector dimebon

Dimebon (Dimebolin) is an antihistamine drug which has been used in Russia since 1983. Recently Dimebolin has attracted renewed interest after being shown to have positive effects on persons suffering from Alzheimer's disease. Animal studies have shown that dimebon acts through multiple mechanisms, both blocking the action of neurotoxic beta-amyloid peptides and inhibiting L-type calcium channels, modulating the action of AMPA and NMDA glutamate receptors. Our experiments with cell culture L929 and mice have shown that dimebon may exert its neuroprotective effect by blocking cytotoxic signals induced by proinflammatory cytokines such as TNF-a which are believed to play a central role in Alzheimer's disease. Dimebon (10 mg/ml) protected mouse fibroblasts L929 against the toxic action of TNF-a. Our study included 65 male mice. TNF-a (10 mg per mouse), dimebon (0,2 mg/kg) and their combination were injected intraperitonealy. Changes in the level of molecular species of sphingomyelin and galactosyl ceramide in hippocampus, cerebellum and cerebral cortex within 30 min, 2 h, 4 h, and 24 h after injection were detected by chromato-mass-spectrometry. Maximal changes in sphingomyelin and galactosyl ceramides contents of different molecular species after single TNF-a administration were found in the hippocampus, and were less expressed in the cerebral cortex and cerebellum after 24 h. Dimebon itself did not induce changes in the sphingolipid spectrum in brain sections, but protected them against disorders induced by TNF-a in the brain. Modern strategies in the search of new therapeutic approaches are based on the multitarget properties of new drugs. According to our results TNF-a may serve as a new target for dimebon.

Disruptions of sensorimotor gating, cytokines, glycemia, monoamines, and genes in both sexes of rats reared in social isolation can be ameliorated by oral chronic quetiapine administration

The pathogenesis of schizophrenia in patients with metabolic abnormalities remains unclear. Our previous study demonstrated that isolation rearing (IR) induced longitudinal concomitant changes of pro-inflammatory cytokine (pro-CK) levels and metabolic abnormalities with a developmental origin. However, the general consensus, believes that these abnormalities are caused by antipsychotic treatment in schizophrenic patients. The IR paradigm presents with face, construct, and predictive validity for schizophrenia. Therefore, we employed IR rats of both sexes to examine whether chronic quetiapine (QTP, a second-generation antipsychotic medication) treatment induces disruptions of metabolism (body weight, blood pressure, and the glycemic and lipid profiles) or cytokines [interleukin (IL)-1 beta, IL-6, IL-10, interferon-gamma, and tumor necrosis factor (TNF)-alpha], and further, whether it reverses deficits of behaviors [locomotor activity and prepulse inhibition (PPI)] and the expression of monoamines (dopamine and serotonin) and related genes (Htr1a, Htr2a, Htr3a, Drd1a, and Gabbr2). IR induced higher levels of pro-CK, dysglycemia, blood pressure, locomotor activity, and impaired PPI, simultaneously destabilizing cortico-striatal monoamines and relevant genes in both sexes, while QTP demonstrated dose-dependent reversal of these changes, suggesting that QTP might reduce the pro-CKs to regulate these abnormalities. Our data implied that antipsychotics may not be the solitary factor causing metabolic problems in schizophrenia and suggested that inflammatory changes may play a vital role in the developmental pathophysiology of schizophrenia and related metabolic abnormalities.

Sleep fragmentation and sepsis differentially impact blood-brain barrier integrity and transport of tumor necrosis factor-α in aging

The factors by which aging predisposes to critical illness are varied, complex, and not well understood. Sepsis is considered a quintessential disease of old age because the incidence and mortality of severe sepsis increases in old and the oldest old individuals. Aging is associated with dramatic changes in sleep quality and quantity and sleep increasingly becomes fragmented with age. In healthy adults, sleep disruption induces inflammation. Multiple aspects of aging and of sleep dysregulation interact via neuroimmune mechanisms. Tumor necrosis factor-α (TNF), a cytokine involved in sleep regulation and neuroimmune processes, exerts some of its effects on the CNS by crossing the blood-brain barrier (BBB). In this study we examined the impact of sepsis, sleep fragmentation, and aging on BBB disruption and TNF transport into brain. We used the cecal ligation and puncture (CLP) model of sepsis in young and aged mice that were either undisturbed or had their sleep disrupted. There was a dichotomous effect of sepsis and sleep disruption with age: sepsis disrupted the BBB and increased TNF transport in young mice but not in aged mice, whereas sleep fragmentation disrupted the BBB and increased TNF transport in aged mice, but not in young mice. Combining sleep fragmentation and CLP did not produce a greater effect on either of these BBB parameters than did either of these manipulations alone. These results suggest that the mechanisms by which sleep fragmentation and sepsis alter BBB functions are fundamentally different from one another and that a major change in the organism's responses to those insults occurs with aging.

Inhibition of Peripheral TNF-α and Downregulation of Microglial Activation by Alpha-Lipoic Acid and Etanercept Protect Rat Brain Against Ischemic Stroke

Ischemic stroke, caused by obstruction of blood flow to the brain, would initiate microglia activation which contributes to neuronal damage. Therefore, inhibition of microglia-mediated neuroinflammation could be a therapeutic strategy for ischemic stroke. This study was aimed to elucidate the anti-inflammatory effects of alpha-lipoic acid and etanercept given either singly or in combination in rats subjected to middle cerebral artery occlusion. Both α-lipoic acid and etanercept markedly reduced cerebral infarct, blood-brain barrier disruption, and neurological motor deficits with the former drug being more effective with the dosage used. Furthermore, when used in combination, the reduction was more substantial. Remarkably, a greater diminution in the serum levels of tumor necrosis factor-alpha as well as the brain levels of microglial activation (e.g., microgliosis, amoeboid microglia, and microglial overexpression of tumor necrosis factor-α) was observed with the combined drug treatment as compared to the drugs given separately. We conclude that inhibition of peripheral tumor necrosis factor-alpha as well as downregulation of brain microglial activation by alpha-lipoic acid or etanercept protect rat brain against ischemic stroke. Moreover, when both drugs were used in combination, the stroke recovery was promoted more extensively.

Sickness: From the focus on cytokines, prostaglandins, and complement factors to the perspectives of neurons

Systemic inflammation leads to a variety of physiological (e.g. fever) and behavioral (e.g. anorexia, immobility, social withdrawal, depressed mood, disturbed sleep) responses that are collectively known as sickness. While these phenomena have been studied for the past few decades, the neurobiological mechanisms by which sickness occurs remain unclear. In this review, we first revisit how the body senses and responds to infections and injuries by eliciting systemic inflammation. Next, we focus on how peripheral inflammatory molecules such as cytokines, prostaglandins, and activated complement factors communicate with the brain to trigger neuroinflammation and sickness. Since depression also involves inflammation, we further elaborate on the interrelationship between sickness and depression. Finally, we discuss how immune activation can modulate neurons in the brain, and suggest future perspectives to help unravel how changes in neuronal functions relate to sickness responses.

Isolation rearing impaired sensorimotor gating but increased pro-inflammatory cytokines and disrupted metabolic parameters in both sexes of rats

Social isolation rearing (SIR) is an early stress paradigm of deprivation of the social contact since weaning. SIR has been used to investigate the mechanisms behind certain mental illnesses with neurodevelopmental origins, including schizophrenia. In schizophrenia, metabolic dysfunction has become a critical issue with increasing evidence for a possible connection between metabolism and immune systems in which metabolic changes are associated with pro-inflammatory cytokine (pro-CK) levels. The present study employed a rat model of SIR with both sexes to examine behaviors [locomotor activity and prepulse inhibition (PPI)], inflammatory markers [C-reactive protein, interleukin (IL)-1 beta, IL-6, IL-10, tumor necrosis factor (TNF)-alpha and interferon-gamma], and metabolism-related variables (body weight, blood pressure, and the profiles of glycemia and lipid). Our results revealed that around puberty, SIR rats of both sexes exhibited behaviorally a higher locomotor activity and a lower PPI performance. Biochemically, SIR rats had an elevated level of pro-CKs (IL-1 beta, IL-6, TNF-alpha, and interferon-gamma), and metabolic abnormalities (increased insulin resistance, decreased insulin sensitivity, and high blood pressure) in a time-dependent manner. The relationships between pro-CKs and metabolism were sex specific as IL-1 beta and interferon-gamma were correlated to glycemia metabolic indexes in males. The present study demonstrated SIR-induced longitudinal concomitant changes of pro-CKs and metabolic abnormalities, implying a more direct role of these two things in mental dysfunctions with a developmental origin.

TNF and angiotensin type 1 receptors interact in the brain control of blood pressure in heart failure

Accumulating evidence suggests that the brain renin-angiotensin system and proinflammatory cytokines, such as TNF-α, play a key role in the neurohormonal activation in chronic heart failure (HF). In this study we tested the involvement of TNF-α and angiotensin type 1 receptors (AT1Rs) in the central control of the cardiovascular system in HF rats.

METHODS

we carried out the study on male Sprague-Dawley rats subjected to the left coronary artery ligation (HF rats) or to sham surgery (sham-operated rats). The rats were pretreated for four weeks with intracerebroventricular (ICV) infusion of either saline (0.25μl/h) or TNF-α inhibitor etanercept (0.25μg/0.25μl/h). At the end of the pretreatment period, we measured mean arterial blood pressure (MABP) and heart rate (HR) at baseline and during 60min of ICV administration of either saline (5μl/h) or AT1Rs antagonist losartan (10μg/5μl/h). After the experiments, we measured the left ventricle end-diastolic pressure (LVEDP) and the size of myocardial scar.

RESULTS

MABP and HR of sham-operated and HF rats were not affected by pretreatments with etanercept or saline alone. In sham-operated rats the ICV infusion of losartan did not affect MABP either in saline or in etanercept pretreated rats. In contrast, in HF rats the ICV infusion of losartan significantly decreased MABP in rats pretreated with saline, but not in those pretreated with etanercept. LVEDP was significantly elevated in HF rats but not in sham-operated ones. Surface of the infarct scar exceeded 30% of the left ventricle in HF groups, whereas sham-operated rats did not manifest evidence of cardiac scarring.

CONCLUSIONS

our study provides evidence that in rats with post-infarction heart failure the regulation of blood pressure by AT1Rs depends on centrally acting endogenous TNF-α.

Assessment of blood-brain barrier function and the neuroinflammatory response in the rat brain by using cerebral open flow microperfusion (cOFM)

Blood-brain barrier (BBB) impairment in systemic inflammation leads to neuroinflammation. Several factors including cytokines, chemokines and signal transduction molecules are implicated in BBB dysfunction in response to systemic inflammation. Here, we have adopted a novel in vivo technique; namely, cerebral open flow microperfusion (cOFM), to perform time-dependent cytokine analysis (TNF-alpha, IL-6 and IL-10) in the frontal cortex of the rat brain in response to a single peripheral administration of lipopolysaccharide (LPS). In parallel, we monitored BBB function using sodium fluorescein as low molecular weight reporter in the cOFM sample. In response to the systemic LPS administration, we observed a rapid increase of TNF-alpha in the serum and brain, which coincides with the BBB disruption. Brain IL-6 and IL-10 synthesis was delayed by approximately 1 h. Our data demonstrate that cOFM can be used to monitor changes in brain cytokine levels and BBB disruption in a rat sepsis model.

The role of pro-inflammatory cytokines in the neuroinflammation and neurogenesis of schizophrenia

Schizophrenia is a serious mental illness with chronic symptoms and significant impairment in psychosocial functioning. Although novel antipsychotics have been developed, the negative and cognitive symptoms of schizophrenia are still unresponsive to pharmacotherapy. The high level of social impairment and a chronic deteriorating course suggest that schizophrenia likely has neurodegenerative characteristics. Inflammatory markers such as pro-inflammatory cytokines are well-known etiological factors for psychiatric disorders, including schizophrenia. Inflammation in the central nervous system is closely related to neurodegeneration. In addition to pro-inflammatory cytokines, microglia also play an important role in the inflammatory process in the CNS. Uncontrolled activity of pro-inflammatory cytokines and microglia can induce schizophrenia in tandem with genetic vulnerability and glutamatergic neurotransmitters. Several studies have investigated the possible effects of antipsychotics on inflammation and neurogenesis. Additionally, anti-inflammatory adjuvant therapy has been under investigation as a treatment option for schizophrenia. Further studies should consider the confounding effects of systemic factors such as metabolic syndrome and smoking. In addition, the unique mechanisms by which pro-inflammatory cytokines are involved in the etiopathology of schizophrenia should be investigated. In this article, we aimed to review (1) major findings regarding neuroinflammation and pro-inflammatory cytokine alterations in schizophrenia, (2) interactions between neuroinflammation and neurogenesis as possible neural substrates for schizophrenia, and (3) novel pharmacological approaches.

Neuroinflammation and comorbidity of pain and depression

Comorbid depression and chronic pain are highly prevalent in individuals suffering from physical illness. Here, we critically examine the possibility that inflammation is the common mediator of this comorbidity, and we explore the implications of this hypothesis. Inflammation signals the brain to induce sickness responses that include increased pain and negative affect. This is a typical and adaptive response to acute inflammation. However, chronic inflammation induces a transition from these typical sickness behaviors into depression and chronic pain. Several mechanisms can account for the high comorbidity of pain and depression that stem from the precipitating inflammation in physically ill patients. These mechanisms include direct effects of cytokines on the neuronal environment or indirect effects via downregulation of G protein-coupled receptor kinase 2, activation of the tryptophan-degrading enzyme indoleamine 2,3-dioxygenase that generates neurotropic kynurenine metabolites, increased brain extracellular glutamate, and the switch of GABAergic neurotransmission from inhibition to excitation. Despite the existence of many neuroimmune candidate mechanisms for the co-occurrence of depression and chronic pain, little work has been devoted so far to critically assess their mediating role in these comorbid symptoms. Understanding neuroimmune mechanisms that underlie depression and pain comorbidity may yield effective pharmaceutical targets that can treat both conditions simultaneously beyond traditional antidepressants and analgesics.

Spinal nociceptive hyperexcitability induced by experimental disc herniation is associated with enhanced local expression of Csf1 and FasL

Sciatica after disc herniation may be associated with compression of spinal nerves, but also inflammatory substances released from the nucleus pulposus (NP) leaking into the spinal canal. Here, in an animal model mimicking clinical intervertebral disc herniation, we investigate the effect of NP on neuronal activity. In anaesthetized Lewis rats, extracellular single-unit recordings of spinal dorsal horn neurons were performed, and the C-fibre responses were examined. Moreover, quantitative polymerase chain reaction was used to explore the gene expression of proinflammatory cytokines in the NP tissue exposed to the spinal dorsal nerve roots L3-L5. In accordance with earlier studies, we showed a significant increase in the C-fibre response and an upregulation of the gene expression of interleukin 1β and tumour necrosis factor 180 minutes after application of NP onto the nerve roots. Moreover, based on a polymerase chain reaction array of 84 common inflammatory cytokines at the same time point, we demonstrated a highly significant upregulation of colony-stimulating factor 1 also termed macrophage colony-stimulating factor and Fas ligand. The pronounced upregulation of Csf1 and Fas ligand 180 minutes after application of NP onto the nerve roots suggests that macrophage activation and apoptosis may be involved in pain hypersensitivity and other sensory abnormalities after disc herniation.

Cytokine signaling modulates blood-brain barrier function

The blood-brain barrier (BBB) provides a vast interface for cytokines to affect CNS function. The BBB is a target for therapeutic intervention. It is essential, therefore, to understand how cytokines interact with each other at the level of the BBB and how secondary signals modulate CNS functions beyond the BBB. The interactions between cytokines and lipids, however, have not been fully addressed at the level of the BBB. Here, we summarize current understanding of the localization of cytokine receptors and transporters in specific membrane microdomains, particularly lipid rafts, on the luminal (apical) surface of the microvascular endothelial cells composing the BBB. We then illustrate the clinical context of cytokine effects on the BBB by neuroendocrine regulation and amplification of inflammatory signals. Two unusual aspects discussed are signaling crosstalk by different classes of cytokines and genetic regulation of drug efflux transporters. We also introduce a novel area of focus on how cytokines may act through nuclear hormone receptors to modulate efflux transporters and other targets. A specific example discussed is the ATP-binding cassette transporter-1 (ABCA-1) that regulates lipid metabolism. Overall, cytokine signaling at the level of the BBB is a crucial feature of the dynamic regulation that can rapidly change BBB function and affect brain health and disease.

Apolipoprotein A-I: insights from redox proteomics for its role in neurodegeneration

Proteomics has a wide range of applications, including determination of differences in the proteome in terms of expression and post-translational protein modifications. Redox proteomics allows the identification of specific targets of protein oxidation in a biological sample. Using proteomic techniques, apolipoprotein A-I (ApoA-I) has been found at decreased levels in subjects with a variety of neurodegenerative disorders including in the serum and cerebrospinal fluid (CSF) of Alzheimer disease (AD), Parkinson disease (PD), and Down syndrome (DS) with gout subjects. ApoA-I plays roles in cholesterol transport and regulation of inflammation. Redox proteomics further showed ApoA-I to be highly oxidatively modified and particularly susceptible to modification by 4-hydroxy-2-trans-nonenal (HNE), a lipid peroxidation product. In the current review, we discuss the consequences of oxidation of ApoA-I in terms of neurodegeneration. ROS-associated chemotherapy related ApoA-I oxidation leads to elevation of peripheral levels of tumor necrosis factor-α (TNF-α) that can cross the blood-brain barrier (BBB) causing a signaling cascade that can contribute to neuronal death, likely a contributor to what patients refer to as "chemobrain." Current evidence suggests ApoA-I to be a promising diagnostic marker as well as a potential target for therapeutic strategies in these neurodegenerative disorders.

Cytokines: how important are they in mediating sickness?

Sickness refers to a set of coordinated physiological and behavioral changes in response to systemic inflammation. It is characterized by fever, malaise, social withdrawal, fatigue, and anorexia. While these responses collectively represent a protective mechanism against infection and injury, increasing lines of evidence indicate that over-exaggerated or persistent sickness can damage the brain, and could possibly raise the risk to developing delirium. Therefore, a clear understanding in sickness will be beneficial. It has long been believed that sickness results from increased systemic cytokines occurring during systemic inflammation. However, in recent years more and more conflicting data have suggested that development of sickness following peripheral immune challenge could be independent of cytokines. Hence, it is confusing as to whether cytokines really do act as primary mediators of sickness, or if they are secondary to alternative inducing factor(s). In this review, we will (1) introduce the relationships between systemic inflammation, cytokines, sickness, and delirium, and (2) attempt to interpret the recent controversies.

Cytokine and chemokine responses in serum and brain after single and repeated injections of lipopolysaccharide: multiplex quantification with path analysis

Administration of the proinflammatory molecule lipopolysaccharide (LPS) alters transport rates for many peptides across the blood-brain barrier (BBB). We and others have previously shown that effects of LPS on BBB transport are highly dependent on the injection paradigm used, and timing of the study. Cytokine expression in both brain and serum compartments influences the BBB response to an inflammatory stimulus, and mediates changes in BBB transport. Here, we used multianalyte technology to simultaneously determine the responses of 13 cytokines and chemokines (G-CSF, GM-CSF, IL-1α, IL-1β, IL-6, IL-10, IL-13, IP-10, KC, MCP-1, MIP-1α, RANTES, and TNF-α) in brain and blood to single and repeated injections of LPS and path analysis to determine the major relations among these analytes. Major findings are: (1) in comparison to measurements taken from a time course after a single injection of LPS, the three injection regimen of LPS produced significantly higher levels in brain for G-CSF, IL-1α, IL-6, MCP-1, MIP-1α, and TNF and in serum for G-CSF, IL-6, and GM-CSF and (2) path analysis distinguished direct from indirect correlations between analyte pairs, with MCP-1, IL-6, G-CSF, and KC mediating relations among these cytokines both within and between serum and brain compartments. These results suggest that potentiation of cytokine levels in brain and serum compartments could play important roles in the regulation of BBB transport, and that our novel application of an established statistical method can be used to assess direct correlations within multiplexed datasets.

2-Mercaptoethane sulfonate prevents doxorubicin-induced plasma protein oxidation and TNF-α release: implications for the reactive oxygen species-mediated mechanisms of chemobrain

Doxorubicin (DOX), an anthracycline used to treat a variety of cancers, is known to generate intracellular reactive oxygen species. Moreover, many patients who have undergone chemotherapy complain of cognitive dysfunction often lasting years after cessation of the chemotherapy. Previously, we reported that intraperitoneal administration of DOX led to elevated TNF-α and oxidative stress in the plasma and brain of mice. However, the mechanisms involved in nontargeted tissue damage remain unknown. In this study, we measured plasma oxidative stress and cytokine levels in patients treated with DOX. We observed increased plasma protein carbonylation and elevation of TNF-α 6 h after DOX administration in the context of multiagent chemotherapy regimens. Importantly, patients not treated coincidentally with 2-mercaptoethane sulfonate (MESNA) showed statistically significantly increased plasma protein-bound 4-hydroxynonenal, whereas those who had been coincidentally treated with MESNA as part of their multiagent chemotherapy regimen did not, suggesting that concomitant administration of the antioxidant MESNA with DOX prevents intravascular oxidative stress. We demonstrate in a murine model that MESNA suppressed DOX-induced increased plasma oxidative stress indexed by protein carbonyls and protein-bound HNE, and also suppressed DOX-induced increased peripheral TNF-α levels. A direct interaction between DOX and MESNA was demonstrated by MESNA suppression of DOX-induced DCF fluorescence. Using redox proteomics, we identified apolipoprotein A1 (APOA1) in both patients and mice after DOX administration as having increased specific carbonyl levels. Macrophage stimulation studies showed that oxidized APOA1 increased TNF-α levels and augmented TNF-α release by lipopolysaccharide, effects that were prevented by MESNA. This study is the first to demonstrate that DOX oxidizes plasma APOA1, that oxidized APOA1 enhances macrophage TNF-α release and thus could contribute to potential subsequent TNF-α-mediated toxicity, and that MESNA interacts with DOX to block this mechanism and suggests that MESNA could reduce systemic side effects of DOX.

The role of cerebral vascular NFkappaB in LPS-induced inflammation: differential regulation of efflux transporter and transporting cytokine receptors

BACKGROUND/AIMS

The transcription factor NFkappaB is a major mediator of lipopolysaccharide (LPS) signaling. We determined the role of NFkappaB activation in regulatory changes of the P-glycoprotein (Pgp) drug efflux transporter at the blood-brain barrier (BBB) and proinflammatory cytokine receptors.

METHODS

We treated NFkappaB knockout and wildtype mice with LPS or vehicle, obtained enriched cerebral microvessels, and determined target mRNA by qPCR for MDR1a/b, IL15Ralpha, IL2 Ralpha, IL2Rgamma, LIFR, gp130, and TNFR1/2, and protein expression by western blotting for P-gp, IL15Ralpha, IL2Rgamma, LIFR, and gp130.

RESULTS

The effects of LPS on the transporters and cytokine receptors showed differences between wildtype and NFkappaB knockout mice, and between mRNA and protein changes. NFkappaB not only mediated the LPS-induced increase of MDR1b, IL2Rgamma, and TNFR2 mRNA in the wildtype mice, but it showed opposite effects by elevating IL15Ralpha and TNFR1 mRNA and decreasing IL2Ralpha in the knockout mice. Although basal vinblastine uptake was unchanged in the NFkappaB knockout mice, LPS induced an increase of the uptake (depressed efflux transport) greater than that seen in the wildtype mice, indicating that NFkappaB helps to maintain Pgp efflux transporter function.

CONCLUSION

The results show differential involvement of NFkappaB signaling in response to LPS at the BBB.

Chemo brain (chemo fog) as a potential side effect of doxorubicin administration: role of cytokine-induced, oxidative/nitrosative stress in cognitive dysfunction

Doxorubicin (ADRIAMYCIN, RUBEX) is a chemotherapeutic agent that is commonly administered to breast cancer patients in standard chemotherapy regimens. As true of all such therapeutic cytotoxic agents, it can damage normal, noncancerous cells and might affect biochemical processes in a manner that might lead to, or contribute to, chemotherapy-induced cognitive deficits when administered either alone or in combination with other agents.