Anandamide inhibits Theiler's virus induced VCAM-1 in brain endothelial cells and reduces leukocyte transmigration in a model of blood brain barrier by activation of CB(1) receptors

Alterations of the blood-brain barrier during aging

The blood-brain barrier (BBB) is a complex and dynamic interface that regulates the exchange of molecules and cells between the blood and the central nervous system. It undergoes structural and functional changes during aging, which may compromise its integrity and contribute to the pathogenesis of neurodegenerative diseases. In recent years, advances in microscopy and high-throughput bioinformatics have allowed a more in-depth investigation of the aging mechanisms of BBB. This review summarizes age-related alterations of the BBB structure and function from six perspectives: endothelial cells, astrocytes, pericytes, basement membrane, microglia and perivascular macrophages, and fibroblasts, ranging from the molecular level to the human multi-system level. These basic components are essential for the proper functioning of the BBB. Recent imaging methods of BBB were also reviewed. Elucidation of age-associated BBB changes may offer insights into BBB homeostasis and may provide effective therapeutic strategies to protect it during aging.

Selected cannabis cultivars modulate glial activation: in vitro and in vivo studies

INTRODUCTION

Multiple sclerosis (MS) is a chronic autoimmune disease of the central nervous system characterized by neuroinflammation, demyelination and axonal loss. Cannabis, an immunomodulating agent, is known for its ability to treat MS effectively. However, due to variations in the profile of secondary metabolites, especially cannabinoids, among cannabis cultivars, the effectiveness of cannabis treatment can vary, with significant variability in the effects on different biological parameters. For screening available cultivars, cellular in vitro as well as pre-clinical in vivo assays, are required to evaluate the effectiveness of the wide range of chemical variability that exists in cannabis cultivars. This study evaluated comparatively three chemically diverse cannabis cultivars, CN2, CN4 and CN6, containing different ratios of phytocannabinoids, for their neuroinflammatory activity in MS model.

MATERIALS AND METHODS

In vitro experiments were performed with lipopolysaccharide (LPS)-activated BV-2 microglia and primary glial cells to evaluate the effect of different cannabis cultivars on nitric oxide (NO) and inflammatory cytokines, as well as inducible nitric oxide synthase (iNOS) protein expression. An in vivo experiment using the experimental autoimmune encephalomyelitis (EAE) MS model was conducted using Myelin oligodendrocyte glycoprotein (MOG) as the activating peptide. The cannabis extracts of the cultivars CN2, CN4, CN6 or vehicle, were intraperitoneally injected with clinical scores given based on observed symptoms over the course of study. At the end of the experiment, the mice were sacrificed, and splenocyte cytokine secretion was measured using ELISA. Lumbar sections from the spinal cord of treated MS mice were evaluated for microglia, astrocytes and CD4+ cells.

RESULTS

Extracts of the CN2 cultivar contained tetrahydrocannabinolic acid (THCA) and tetrahydrocannabinol (THC) without cannabidiol (CBD), and a number of monoterpenes. CN4 contained cannabidiolic acid (CBDA) and tetrahydrocannabidiolic acid (THCA), with significant amounts of THC: CBD in a 1:1 ratio, as well as sesquiterpenes and some monoterpenes; and CN6 contained primarily CBDA and THCA, as well as THC and CBD in a 2:1 ratio, with some sesquiterpenes and no monoterpenes. All extracts were not cytotoxic in glial cells up to 50 µg/ml. Dose dependent inhibition of LPS-induced BV2 as well as primary microglial NO secretion confirmed the anti-inflammatory and anti-oxidative activity of the three cannabis cultivars. CN2 but not CN4 reduced both astrocytosis and microglial activation in lumbar sections of EAE mice. In contrast, CN4 but not CN2 significantly decreased the secretion of TNFα and Interferon γ (IFNγ) in primary splenocytes extracted from EAE mice.

CONCLUSIONS

While both cannabis cultivars, CN2 and CN4, significantly reduced the severity of the clinical signs throughout the course of the study, they modulated different inflammatory mediators and pathways, probably due to differences in their phytocannabinoid composition. This demonstrates the differential potential of cannabis cultivars differing in chemotype to regulate neuroinflammation and their potential to treat MS.

The Therapeutic Potential of the Endocannabinoid System in Age-Related Diseases

The endocannabinoid system (ECS) dynamically regulates many aspects of mammalian physiology. ECS has gained substantial interest since growing evidence suggests that it also plays a major role in several pathophysiological conditions due to its ability to modulate various underlying mechanisms. Furthermore, cannabinoids, as components of the cannabinoid system (CS), have proven beneficial effects such as anti-inflammatory, immunomodulatory, neuromodulatory, antioxidative, and cardioprotective effects. In this comprehensive review, we aimed to describe the complex interaction between CS and most common age-related diseases such as neuro-degenerative, oncological, skeletal, and cardiovascular disorders, together with the potential of various cannabinoids to ameliorate the progression of these disorders. Since chronic inflammation is postulated as the pillar of all the above-mentioned medical conditions, we also discuss in this paper the potential of CS to ameliorate aging-associated immune system dysregulation.

Diversified Effects of COVID-19 as a Consequence of the Differential Metabolism of Phospholipids and Lipid Peroxidation Evaluated in the Plasma of Survivors and Deceased Patients upon Admission to the Hospital

As a result of SARS-CoV-2 infection, inflammation develops, which promotes oxidative stress, leading to modification of phospholipid metabolism. Therefore, the aim of this study is to compare the effects of COVID-19 on the levels of phospholipid and free polyunsaturated fatty acids (PUFAs) and their metabolites produced in response to reactions with reactive oxygen species (ROS) and enzymes (cyclooxygenases-(COXs) and lipoxygenase-(LOX)) in the plasma of patients who either recovered or passed away within a week of hospitalization. In the plasma of COVID-19 patients, especially of the survivors, the actions of ROS and phospholipase A2 (PLA2) cause a decrease in phospholipid fatty acids level and an increase in free fatty acids (especially arachidonic acid) despite increased COXs and LOX activity. This is accompanied by an increased level in lipid peroxidation products (malondialdehyde and 8-isoprostaglandin F2α) and lipid mediators generated by enzymes. There is also an increase in eicosanoids, both pro-inflammatory as follows: thromboxane B2 and prostaglandin E2, and anti-inflammatory as follows: 15-deoxy-Δ-12,14-prostaglandin J2 and 12-hydroxyeicosatetraenoic acid, as well as endocannabinoids (anandamide-(AEA) and 2-arachidonylglycerol-(2-AG)) observed in the plasma of patients who recovered. Moreover, the expression of tumor necrosis factor α and interleukins (IL-6 and IL-10) is increased in patients who recovered. However, in the group of patients who died, elevated levels of N-oleoylethanolamine and N-palmitoylethanolamine are found. Since lipid mediators may have different functions depending on the onset of pathophysiological processes, a stronger pro-inflammatory response in patients who have recovered may be the result of the defensive response to SARS-CoV-2 in survivors associated with specific changes in the phospholipid metabolism, which could also be considered a prognostic factor.

Endocannabinoid system in the neuroendocrine response to LPS-induced immune challenge

The endocannabinoid system plays a key role in the intersection of the nervous, endocrine, and immune system, regulating not only their functions but also how they interplay with each other. Endogenous ligands, named endocannabinoids, are produced “on demand” to finely regulate the synthesis and secretion of hormones and neurotransmitters, as well as to regulate the production of cytokines and other proinflammatory mediators.

It is well known that immune challenges, such as exposure to lipopolysaccharide (LPS), the main component of the Gram-negative bacteria cell wall, disrupts not only the hypothalamic-pituitary-adrenal axis but also affects other endocrine systems such as the hypothalamic-pituitary-gonadal axis and the release of oxytocin from the neurohypophysis. Here we explore which actors and molecular mechanisms are involved in these processes.

URB597 and Andrographolide Improve Brain Microvascular Endothelial Cell Permeability and Apoptosis by Reducing Oxidative Stress and Inflammation Associated with Activation of Nrf2 Signaling in Oxygen-Glucose Deprivation

Ischemic stroke, a cerebrovascular disease worldwide, triggers a cascade of pathophysiological events, including blood-brain barrier (BBB) breakdown. Brain microvascular endothelial cells (BMECs) play a vital role in maintaining BBB function. The injury of BMECs may worsen neurovascular dysfunction and patients' prognosis. Therefore, uncover the principal molecular mechanisms involved in BBB disruption in stroke becomes pressing. The endocannabinoid system (ECS) has been implicated in increasingly physiological functions, both in neurometabolism and cerebrovascular regulation. Modulating its activities by the fatty acid amide hydrolase (FAAH) shows anti-inflammatory characteristics. Andrographolide (AG), one Chinese herbal ingredient, has also attracted attention for its role in immunomodulatory and as a therapeutic target in BBB disorders. Recently, the FAAH inhibitor URB597 and AG have important regulatory effects on neuronal and vascular cells in ischemia. However, the effects of URB597 and AG on BMEC permeability and apoptosis in oxygen-glucose deprivation (OGD) and the underlying mechanisms remain unclear. To address these issues, cultured BMECs (bEnd.3 cells) were exposed to OGD. The cell viability, permeability, tube formation, and apoptosis were assessed following treatment with URB597, AG, and cotreatment. Mitochondrial membrane potential (MMP), reactive oxygen species (ROS), superoxide dismutase (SOD), catalase (CAT), malondialdehyde (MDA), proinflammatory factors, tight junction (TJ) proteins, and oxidative stress-mediated Nrf2 signaling were also investigated. Results revealed that OGD broke the endothelial barrier, cell viability, MMP, and tube formation, which was reversed by URB597 and AG. OGD-induced enhancement of ROS, MDA, and apoptosis was reduced after drug interventions. URB597 and AG exhibited antioxidant/anti-inflammatory and mitochondrial protective effects by activating Nrf2 signaling. These findings indicated that URB597 and AG protect BMECs against OGD-induced endothelial permeability impairment and apoptosis by reducing mitochondrial oxidative stress and inflammation associated with activation of Nrf2 signaling. URB597 and AG showing the vascular protection may have therapeutic potential for the BBB damage in ischemic cerebrovascular diseases.

Comparative study of CNR1 and CNR2 cannabinoid receptors expression levels in COVID-19 patients with and without diabetes mellitus: Recommendations for future research targets

BACKGROUND AND AIMS

The COVID-19 pandemic has prompted researchers to look for effective therapeutic targets. The effect of endocannabinoid system against infectious diseases is investigated for several years. In this study, we evaluated the expression level of CNR1 and CNR2 genes in patients with COVID-19 with and without diabetes to provide new insights regarding these receptors and their potential effect in COVID-19 disease.

METHODS

In this study, peripheral blood monocytes cells (PBMCs) were isolated from eight different groups including COVID-19 patients, diabetic patients, and healthy individuals. RNA were extracted to evaluate the expression level of CNR1 and CNR2 genes using real-time PCR. The correlation between the expression levels of these genes in different groups were assessed.

RESULTS

A total of 80 samples were divided into 8 groups, with each group consisting of ten samples. When comparing severe and moderate COVID-19 groups to healthy control group, the expression levels of the CNR1 and CNR2 genes were significantly higher in the severe and moderate COVID-19 groups. There were no significant differences between the mild COVID-19 group and the healthy control group. It was found that the expression levels of these genes in patients with diabetes who were infected with SARS-COV-2 did not differ across COVID-19 groups with varying severity, but they were significantly higher when compared to healthy controls.

CONCLUSION

Our study suggests the possible role of endocannabinoid system during SARS-COV-2 pathogenicity as the expression of CNR1 and CNR2 were elevated during the disease.

On the Biomedical Properties of Endocannabinoid Degradation and Reuptake Inhibitors: Pre-clinical and Clinical Evidence

The endocannabinoid system (ECS) is composed of endogenous cannabinoids; components involved in their synthesis, transport, and degradation; and an expansive variety of cannabinoid receptors. Hypofunction or deregulation of the ECS is related to pathological conditions. Consequently, endogenous enhancement of endocannabinoid levels and/or regulation of their metabolism represent promising therapeutic approaches. Several major strategies have been suggested for the modulation of the ECS: (1) blocking endocannabinoids degradation, (2) inhibition of endocannabinoid cellular uptake, and (3) pharmacological modulation of cannabinoid receptors as potential therapeutic targets. Here, we focused in this review on degradation/reuptake inhibitors over cannabinoid receptor modulators in order to provide an updated synopsis of contemporary evidence advancing mechanisms of endocannabinoids as pharmacological tools with therapeutic properties for the treatment of several disorders. For this purpose, we revisited the available literature and reported the latest advances regarding the biomedical properties of fatty acid amide hydrolase and monoacylglycerol lipase inhibitors in pre-clinical and clinical studies. We also highlighted anandamide and 2-arachidonoylglycerol reuptake inhibitors with promising results in pre-clinical studies using in vitro and animal models as an outlook for future research in clinical trials.

The Endocannabinoid System: A Potential Target for the Treatment of Various Diseases

The Endocannabinoid System (ECS) is primarily responsible for maintaining homeostasis, a balance in internal environment (temperature, mood, and immune system) and energy input and output in living, biological systems. In addition to regulating physiological processes, the ECS directly influences anxiety, feeding behaviour/appetite, emotional behaviour, depression, nervous functions, neurogenesis, neuroprotection, reward, cognition, learning, memory, pain sensation, fertility, pregnancy, and pre-and post-natal development. The ECS is also involved in several pathophysiological diseases such as cancer, cardiovascular diseases, and neurodegenerative diseases. In recent years, genetic and pharmacological manipulation of the ECS has gained significant interest in medicine, research, and drug discovery and development. The distribution of the components of the ECS system throughout the body, and the physiological/pathophysiological role of the ECS-signalling pathways in many diseases, all offer promising opportunities for the development of novel cannabinergic, cannabimimetic, and cannabinoid-based therapeutic drugs that genetically or pharmacologically modulate the ECS via inhibition of metabolic pathways and/or agonism or antagonism of the receptors of the ECS. This modulation results in the differential expression/activity of the components of the ECS that may be beneficial in the treatment of a number of diseases. This manuscript in-depth review will investigate the potential of the ECS in the treatment of various diseases, and to put forth the suggestion that many of these secondary metabolites of Cannabis sativa L. (hereafter referred to as "C. sativa L." or "medical cannabis"), may also have potential as lead compounds in the development of cannabinoid-based pharmaceuticals for a variety of diseases.

Endocannabinoid Receptors in the CNS: Potential Drug Targets for the Prevention and Treatment of Neurologic and Psychiatric Disorders

The endocannabinoid system participates in the regulation of CNS homeostasis and functions, including neurotransmission, cell signaling, inflammation and oxidative stress, as well as neuronal and glial cell proliferation, differentiation, migration and survival. Endocannabinoids are produced by multiple cell types within the CNS and their main receptors, CB₁ and CB₂, are expressed in both neurons and glia. Signaling through these receptors is implicated in the modulation of neuronal and glial alterations in neuroinflammatory, neurodegenerative and psychiatric conditions, including Alzheimer’s, Parkinson’s and Huntington’s disease, multiple sclerosis, amyotrophic lateral sclerosis, stroke, epilepsy, anxiety and depression. The therapeutic potential of endocannabinoid receptors in neurological disease has been hindered by unwelcome side effects of current drugs used to target them; however, due to their extensive expression within the CNS and their involvement in physiological and pathological process in nervous tissue, they are attractive targets for drug development. The present review highlights the potential applications of the endocannabinoid system for the prevention and treatment of neurologic and psychiatric disorders.

The lipid biology of sepsis

Sepsis, defined as the dysregulated immune response to an infection leading to organ dysfunction, is one of the leading causes of mortality around the globe. Despite the significant progress in delineating the underlying mechanisms of sepsis pathogenesis, there are currently no effective treatments or specific diagnostic biomarkers in the clinical setting. The perturbation of cell signaling mechanisms, inadequate inflammation resolution, and energy imbalance, all of which are altered during sepsis, are also known to lead to defective lipid metabolism. The use of lipids as biomarkers with high specificity and sensitivity may aid in early diagnosis and guide clinical decision making. In addition, identifying the link between specific lipid signatures and their role in sepsis pathology may lead to novel therapeutics. In this review, we discuss the recent evidence on dysregulated lipid metabolism both in experimental and human sepsis focused on bioactive lipids, fatty acids, and cholesterol as well as the enzymes regulating their levels during sepsis. We highlight not only their potential roles in sepsis pathogenesis but also the possibility of using these respective lipid compounds as diagnostic and prognostic biomarkers of sepsis.

Neuroprotective and Immunomodulatory Action of the Endocannabinoid System under Neuroinflammation

Endocannabinoids (eCBs) are lipid-based retrograde messengers with a relatively short half-life that are produced endogenously and, upon binding to the primary cannabinoid receptors CB_1/2, mediate multiple mechanisms of intercellular communication within the body. Endocannabinoid signaling is implicated in brain development, memory formation, learning, mood, anxiety, depression, feeding behavior, analgesia, and drug addiction. It is now recognized that the endocannabinoid system mediates not only neuronal communications but also governs the crosstalk between neurons, glia, and immune cells, and thus represents an important player within the neuroimmune interface. Generation of primary endocannabinoids is accompanied by the production of their congeners, the N-acylethanolamines (NAEs), which together with N-acylneurotransmitters, lipoamino acids and primary fatty acid amides comprise expanded endocannabinoid/endovanilloid signaling systems. Most of these compounds do not bind CB_1/2, but signal via several other pathways involving the transient receptor potential cation channel subfamily V member 1 (TRPV1), peroxisome proliferator-activated receptor (PPAR)-α and non-cannabinoid G-protein coupled receptors (GPRs) to mediate anti-inflammatory, immunomodulatory and neuroprotective activities. In vivo generation of the cannabinoid compounds is triggered by physiological and pathological stimuli and, specifically in the brain, mediates fine regulation of synaptic strength, neuroprotection, and resolution of neuroinflammation. Here, we review the role of the endocannabinoid system in intrinsic neuroprotective mechanisms and its therapeutic potential for the treatment of neuroinflammation and associated synaptopathy.

Mechanistic insights into the protective effect of paracetamol against rotenone-induced Parkinson's disease in rats: Possible role of endocannabinoid system modulation

Parkinson's disease (PD) is a disabling progressive neurodegenerative disease. So far, PD's treatment remains symptomatic with no curative effects. Aside from its blatant analgesic and antipyretic efficacy, recent studies highlighted the endowed neuroprotective potentials of paracetamol (PCM). To this end: the present study investigated: (1) Possible protective role of PCM against rotenone-induced PD-like neurotoxicity in rats, and (2) the mechanisms underlying its neuroprotective actions including cannabinoid receptors' modulation. A dose-response study was conducted using three doses of PCM (25, 50, and 100 mg/kg/day, i.p.) and their effects on body weight changes, spontaneous locomotor activity, rotarod test, tyrosine hydroxylase (TH) and α-synuclein expression, and striatal dopamine (DA) content were evaluated. Results revealed that PCM (100 mg/kg/day, i.p.) halted PD motor impairment, prevented rotenone-induced weight loss, restored normal histological tissue structure, reversed rotenone-induced reduction in TH expression and striatal DA content, and markedly decreased midbrain and striatal α-synuclein expression in rotenone-treated rats. Accordingly, PCM (100 mg/kg/day, i.p.) was selected for further mechanistic investigations, where it ameliorated rotenone-induced oxidative stress, neuro-inflammation, apoptosis, and disturbed cannabinoid receptors' expression. In conclusion, our findings imply a multi-target neuroprotective effect of PCM in PD which could be attributed to its antioxidant, anti-inflammatory and anti-apoptotic activities, in addition to cannabinoid receptors' modulation.

Cannabinoids and COVID-19

Since the endocannabinoid system is involved in immune function, the effect of cannabinoid intake on infectious conditions is questioned for several years and is of particular interest in the COVID 19 pandemia. Some data suggest that the immunomodulatory effect of cannabinoids may affect the course and severity of SARS-CoV-2 infection. Given the large number of cannabinoids consumers in the community, this commentary presents the current knowledge on the potential impact of cannabinoids and endocannabinoids on bacterial and viral infection courses namely SARS-CoV-2 disease. Practical recommendations, which can be drawn from the literature, are given.

Cannabinoid-Induced Immunomodulation during Viral Infections: A Focus on Mitochondria

This review examines the impact of cannabinoids on viral infections, as well as its effects on the mitochondria of the nervous and immune system. The paper conveys information about the beneficial and negative impacts of cannabinoids on viral infections, especially HIV-1. These include effects on the inflammatory response as well as neuroprotective effects. We also explore non-apoptotic mitochondrial pathways modulated by the activity of cannabinoids, resulting in modifications to cellular functions. As a large part of the literature derives from studies of the nervous system, we first compile the information related to mitochondrial functions in this system, particularly through the CB1 receptor. Finally, we reflect on how this knowledge could complement what has been demonstrated in the immune system, especially in the context of the CB2 receptor and Ca²⁺ uptake. The overall conclusion of the review is that cannabinoids have the potential to affect a broad range of cell types through mitochondrial modulation, be it through receptor-specific action or not, and that this pathway has a potential implication in cases of viral infection.

Cannabinoids, Blood-Brain Barrier, and Brain Disposition

Potential therapeutic actions of the cannabinoids delta-9-tetrahydrocannabinol (THC) and cannabidiol (CBD) are based on their activity as analgesics, anti-emetics, anti-inflammatory agents, anti-seizure compounds. THC and CBD lipophilicity and their neurological actions makes them candidates as new medicinal approaches to treat central nervous system (CNS) diseases. However, they show differences about penetrability and disposition in the brain. The present article is an overview about THC and CBD crossing the blood-brain barrier (BBB) and their brain disposition. Several findings indicate that CBD can modify the deleterious effects on BBB caused by inflammatory cytokines and may play a pivotal role in ameliorating BBB dysfunction consequent to ischemia. Thus supporting the therapeutic potential of CBD for the treatment of ischemic and inflammatory diseases of CNS. Cannabinoids positive effects on cognitive function could be also considered through the aspect of protection of BBB cerebrovascular structure and function, indicating that they may purchase substantial benefits through the protection of BBB integrity. Delivery of these cannabinoids in the brain following different routes of administration (subcutaneous, oral, and pulmonary) is illustrated and commented. Finally, the potential role of cannabinoids in drug-resistance in the clinical management of neurological or psychiatric diseases such as epilepsy and schizophrenia is discussed on the light of their crossing the BBB.

Perspectives on Cannabis-Based Therapy of Multiple Sclerosis: A Mini-Review

The consistency, efficacy, and safety of cannabis-based medicines have been demonstrated in humans, leading to the approval of the first cannabis-based therapy to alleviate spasticity and pain associated with multiple sclerosis (MS). Indeed, the evidence supporting the therapeutic potential of cannabinoids for the management of pathological events related to this disease is ever increasing. Different mechanisms of action have been proposed for cannabis-based treatments in mouse models of demyelination, such as Experimental Autoimmune Encephalomyelitis (EAE) and Theiler’s Murine Encephalomyelitis Virus-Induced Demyelinating Disease (TMEV-IDD). Cells in the immune and nervous system express the machinery to synthesize and degrade endocannabinoids, as well as their CB1 and CB2 receptors, each mediating different intracellular pathways upon activation. Hence, the effects of cannabinoids on cells of the immune system, on the blood-brain barrier (BBB), microglia, astrocytes, oligodendrocytes and neurons, potentially open the way for a plethora of therapeutic actions on different targets that could aid the management of MS. As such, cannabinoids could have an important impact on the outcome of MS in terms of the resolution of inflammation or the potentiation of endogenous repair in the central nervous system (CNS), as witnessed in the EAE, TMEV-IDD and toxic demyelination models, and through other in vitro approaches. In this mini review article, we summarize what is currently known about the peripheral and central effects of cannabinoids in relation to the neuroinflammation coupled to MS. We pay special attention to their effects on remyelination and axon preservation within the CNS, considering the major questions raised in the field and future research directions.

Microglial Phenotypes and Their Relationship to the Cannabinoid System: Therapeutic Implications for Parkinson's Disease

Parkinson’s disease is a neurodegenerative disorder, the motor symptoms of which are associated classically with Lewy body formation and nigrostriatal degeneration. Neuroinflammation has been implicated in the progression of this disease, by which microglia become chronically activated in response to α-synuclein pathology and dying neurons, thereby acquiring dishomeostatic phenotypes that are cytotoxic and can cause further neuronal death. Microglia have a functional endocannabinoid signaling system, expressing the cannabinoid receptors in addition to being capable of synthesizing and degrading endocannabinoids. Alterations in the cannabinoid system—particularly an upregulation in the immunomodulatory CB₂ receptor—have been demonstrated to be related to the microglial activation state and hence the microglial phenotype. This paper will review studies that examine the relationship between the cannabinoid system and microglial activation, and how this association could be manipulated for therapeutic benefit in Parkinson’s disease.

Opioid and Endocannabinoid System in Orofacial Pain

Orofacial pain disorders are frequent in the general population and their pharmacological treatment is difficult and controversial. Therefore, the search for novel, safe and efficient analgesics is an important but still elusive goal for contemporary medicine. In the recent years, the antinociceptive potential of endocannabinoids and opioids has been emphasized. However, concerns for the safety of their use limit their clinical applications. the possibility of modulating the activity of endocannabinoids by regulation of their synthesis and/or degradation offers an innovative approach to the treatment of pain. A rat model of trigeminal pain, utilizing tongue jerks evoked by electrical tooth pulp stimulation during perfusion of the cerebral ventricles with various neurotransmitter solutions can be used in the pharmacological studies of nociception in the orofacial area. The aim of this review is to present the effects of pharmacological activity of opioids and endocannabinoids affecting the transmission of the sensory information from the orofacial area on the example of trigemino-hypoglossal reflex in rats.

The endocannabinoid 2-AG enhances spontaneous remyelination by targeting microglia

Remyelination is an endogenous process by which functional recovery of damaged neurons is achieved by reinstating the myelin sheath around axons. Remyelination has been documented in multiple sclerosis (MS) lesions and experimental models, although it is often incomplete or fails to affect the integrity of the axon, thereby leading to progressive disability. Microglia play a crucial role in the clearance of the myelin debris produced by demyelination and in inflammation-dependent OPC activation, two processes necessary for remyelination to occur. We show here that following corpus callosum demyelination in the TMEV-IDD viral murine model of MS, there is spontaneous and partial remyelination that involves a temporal discordance between OPC mobilization and microglia activation. Pharmacological treatment with the endocannabinoid 2-AG enhances the clearance of myelin debris by microglia and OPC differentiation, resulting in complete remyelination and a thickening of the myelin sheath. These results highlight the importance of targeting microglia during the repair processes in order to enhance remyelination.

The Dose-Response Effect of Lycopene on Cerebral Vessel and Neuron Impairment Induced by Hyperlipidemia

To study the dose-response effect of lycopene on vessel and neuron damage in the brain against hyperlipidemia, rats were fed with hypercholesterolemic feed and treated with lycopene orally by gavage at the dose of 5, 25, 45, 65, 85, and 105, 125 mg/kg/bw^-1/d^-1. At the end of the fourth week, lycopene doses and serum lycopene concentration showed an inverse U-shape curve. Serum lycopene concentration was negatively correlated with the levels of serum TC, TG, LDL-C, as well as the cerebral LDL-C, VEGF, and VCAM-1. Serum lycopene concentration was positively correlated with the expression of Claudin-5 and the number of neurons in hippocampal CA1 and CA3. Lycopene could also reduce the pathologic change of these areas. These results suggested an inverse U-shape relation between dose and serum concentration of lycopene, and intermediate doses were most effective to protect cerebral vessels and neurons from being damaged by hyperlipidemia.

A Programmed Anti-Inflammatory Nanoscaffold (PAIN) as a 3D Tool to Understand the Brain Injury Response

Immunology is the next frontier of nano/biomaterial science research, with the immune system determining the degree of tissue repair. However, the complexity of the inflammatory response represents a significant challenge that is essential to understand for the development of future therapies. Cell-instructive 3D culture environments are critical to improve our understanding of the link between the behavior and morphology of inflammatory cells and to remodel their response to injury. This study has taken two recent high-profile innovations-functional peptide-based hydrogels, and the inclusion of anti-inflammatory agents via coassembly-to make a programmed anti-inflammatory nanoscaffold (PAIN) with unusual and valuable properties that allows tissue-independent switching of the inflammatory cascade. Here, extraordinary durability of the anti-inflammatory agent allows, for the first time, the development of a 3D culture system that maintains the growth and cytoskeletal reorganization of brain tissue, while also facilitating the trophic behavior of brain cells for 22 d in vitro. Notably, this behavior was confirmed within an active scar site due to the unprecedented resilience to the presence of inflammatory cells and enzymes in the brain. Efficacy of the culture system is demonstrated via novel insights about inflammatory cell behavior, which would be impossible to obtain via in vivo experimentation.

Gut microbiota, cannabinoid system and neuroimmune interactions: New perspectives in multiple sclerosis

The gut microbiota plays a fundamental role on the education and function of the host immune system. Immunological dysregulation is the cause of numerous human disorders such as autoimmune diseases and metabolic disorders frequently associated with inflammatory processes therefore is critical to explore novel mechanisms involved in maintaining the immune system homeostasis. The cannabinoid system and related bioactive lipids participate in multiple central and peripheral physiological processes that affect metabolic, gastrointestinal and neuroimmune regulatory mechanisms displaying a modulatory role and contributing to the maintenance of the organism's homeostasis. In this review, we gather the knowledge on the gut microbiota-endocannabinoids interactions and their impact on autoimmune disorders such as inflammatory bowel disease, rheumatoid arthritis and particularly, multiple sclerosis (MS) as the best example of a CNS autoimmune disorder. Furthermore, we contribute to this field with new data on changes in many elements of the cannabinoid system in a viral model of MS after gut microbiota manipulation by both antibiotics and probiotics. Finally, we highlight new therapeutic opportunities, under an integrative view, targeting the eCBS and the commensal microbiota in the context of neuroinflammation and MS.

Brain endocannabinoid signaling exhibits remarkable complexity

The endocannabinoid (eCB) signaling system is one of the most extensive of the mammalian brain. Despite the involvement of only few specific ligands and receptors, the system encompasses a vast diversity of triggered mechanisms and driven effects. It mediates a wide range of phenomena, including the regulation of transmitter release, neural excitability, synaptic plasticity, impulse spread, long-term neuronal potentiation, neurogenesis, cell death, lineage segregation, cell migration, inflammation, oxidative stress, nociception and the sleep cycle. It is also known to be involved in the processes of learning and memory formation. This extensive scope of action is attained by combining numerous variables. In a properly functioning brain, the correlations of these variables are kept in a strictly controlled balance; however, this balance is disrupted in many pathological conditions. However, while this balance is known to be disrupted by drugs in the case of addicts, the stimuli and mechanisms influencing the neurodegenerating brain remain elusive. This review examines the multiple factors and phenomena affecting the eCB signaling system in the brain. It evaluates techniques of controlling the eCB system to identify the obstacles in their applications and highlights the crucial interdependent variables that may influence biomedical research outcomes.

2-AG limits Theiler's virus induced acute neuroinflammation by modulating microglia and promoting MDSCs

The innate immune response is mediated by primary immune modulators such as cytokines and chemokines that together with immune cells and resident glia orchestrate CNS immunity and inflammation. Growing evidence supports that the endocannabinoid 2-arachidonoylglycerol (2-AG) exerts protective actions in CNS injury models. Here, we used the acute phase of Theiler's virus induced demyelination disease (TMEV-IDD) as a model of acute neuroinflammation to investigate whether 2-AG modifies the brain innate immune responses to TMEV and CNS leukocyte trafficking. 2-AG or the inhibition of its hydrolysis diminished the reactivity and number of microglia at the TMEV injection site reducing their morphological complexity and modulating them towards an anti-inflammatory state via CB2 receptors. Indeed, 2-AG dampened the infiltration of immune cells into the CNS and inhibited their egress from the spleen, resulting in long-term beneficial effects at the chronic phase of the disease. Intriguingly, it is not a generalized action over leukocytes since 2-AG increased the presence and suppressive potency of myeloid derived suppressor cells (MDSCs) in the brain resulting in higher apoptotic CD4⁺ T cells at the injection site. Together, these data suggest a robust modulatory effect in the peripheral and central immunity by 2-AG and highlight the interest of modulating endogenous cannabinoids to regulate CNS inflammatory conditions.

Oxytocin inhibits ox-LDL-induced adhesion of monocytic THP-1 cells to human brain microvascular endothelial cells

The attachment of monocytes to human brain microvascular endothelial cells (HBMVEs) caused by oxidized low-density lipoprotein (ox-LDL) is associated with an early event and the pathological progression of cerebrovascular diseases. Oxytocin (OT) is a human peptide hormone that is traditionally used as a medication to facilitate childbirth. However, little information is available regarding the physiological function of OT in brain endothelial dysfunction. In the present study, our results indicate that the oxytocin receptor (OTR) was expressed in human brain microvascular endothelial cells (HBMVEs) and was upregulated in response to ox-LDL in a concentration-dependent manner. Notably, OT significantly suppressed ox-LDL-induced attachment of THP-1 monocytes to HBMVEs. Furthermore, we found that OT reduced the expression of adhesion molecules, such as VCAM-1 and E-selectin. Interestingly, it was shown that OT could restore ox-LDL-induced reduction of KLF4 in HBMVEs. Importantly, knockdown of KLF4 abolished the inhibitory effects of OT on ox-LDL-induced expressions of VCAM-1 and E-selectin as well as the adhesion of human monocytic THP-1 cells to endothelial HBMVEs. Mechanistically, we found that the stimulatory effects of OT on KLF4 expression are mediated by the MEK5/MEF2A pathway.

N-Stearoylethanolamine protects the brain and improves memory of mice treated with lipopolysaccharide or immunized with the extracellular domain of α7 nicotinic acetylcholine receptor

Neuroinflammation is an important risk factor for neurodegenerative disorders like Alzheimer's disease. Nicotinic acetylcholine receptors of α7 subtype (α7 nAChRs) regulate inflammatory processes in various tissues, including the brain. N-stearoylethanolamine (NSE) is a biologically active cell membrane component with anti-inflammatory and membrane-protective properties. Previously we found that mice injected with bacterial lipopolysaccharide (LPS) or immunized with recombinant extracellular domain (1-208) of α7 nAChR subunit possessed decreased α7 nAChR levels, accumulated pathogenic amyloid-beta peptide Aβ(1-42) in the brain and demonstrated impaired episodic memory compared to non-treated mice. Here we studied the effect of NSE on behavior and brain components of LPS- treated or α7(1-208)-immunized mice. NSE, given per os, non-significantly decreased LPS-stimulated interleukin-6 elevation in the brain, slowed down the α7(1-208)-specific IgG antibody production and prevented the antibody penetration into the brain of mice. NSE prevented the loss of α7 nAChRs and accumulation of α7-bound Aβ(1-42) in the brain and brain mitochondria of LPS-treated or α7(1-208)-immunized mice and supported mitochondria resistance to apoptosis by attenuating Ca²⁺-stimulated cytochrome c release. Finally, NSE significantly improved episodic memory of mice impaired by either LPS treatment or immunization with α7(1-208). The results of our study demonstrate a therapeutic potential of NSE for prevention of cognitive disfunction caused by neuroinflammation or autoimmune reaction that allows suggesting this drug as a candidate for the treatment or prophylaxis of Alzheimer's pathology.

Cannabinoids and GI Disorders: Endogenous and Exogenous

OPINION STATEMENT

Despite the political and social controversy affiliated with it, the medical community must come to the realization that cannabinoids exist as a ubiquitous signaling system in many organ systems. Our understanding of cannabinoids and how they relate not only to homeostasis but also in disease states must be furthered through research, both clinically and in the laboratory. The identification of the cannabinoid receptors in the early 1990s have provided us with the perfect target of translational research. Already, much has been done with cannabinoids and the nervous system. Here, we explore the implications it has for the gastrointestinal tract. Most therapeutics currently on the market presently target only one aspect of the cannabinoid system. Our main purpose here is to highlight areas of research and potential avenues of discovery that the cannabinoid system has yet to reveal.

Chromenopyrazole, a Versatile Cannabinoid Scaffold with in Vivo Activity in a Model of Multiple Sclerosis

A combination of molecular modeling and structure-activity relationship studies has been used to fine-tune CB2 selectivity in the chromenopyrazole ring, a versatile CB1/CB2 cannabinoid scaffold. Thus, a series of 36 new derivatives covering a wide range of structural diversity has been synthesized, and docking studies have been performed for some of them. Biological evaluation of the new compounds includes, among others, cannabinoid binding assays, functional studies, and surface plasmon resonance measurements. The most promising compound [43 (PM226)], a selective and potent CB2 agonist isoxazole derivative, was tested in the acute phase of Theiler's murine encephalomyelitis virus-induced demyelinating disease (TMEV-IDD), a well-established animal model of primary progressive multiple sclerosis. Compound 43 dampened neuroinflammation by reducing microglial activation in the TMEV.

For whom the endocannabinoid tolls: Modulation of innate immune function and implications for psychiatric disorders

Toll-like receptors (TLRs) mediate the innate immune response to pathogens and are critical in the host defence, homeostasis and response to injury. However, uncontrolled and aberrant TLR activation can elicit potent effects on neurotransmission and neurodegenerative cascades and has been proposed to trigger the onset of certain neurodegenerative disorders and elicit detrimental effects on the progression and outcome of established disease. Over the past decade, there has been increasing evidence demonstrating that the endocannabinoid system can elicit potent modulatory effects on inflammatory processes, with clinical and preclinical evidence demonstrating beneficial effects on disease severity and symptoms in several inflammatory conditions. This review examines the evidence supporting a modulatory effect of endocannabinoids on TLR-mediated immune responses both peripherally and centrally, and the implications for psychiatric disorders such as depression and schizophrenia.

Endocannabinoids and the Cardiovascular System in Health and Disease

The endocannabinoid system is widely distributed throughout the cardiovascular system. Endocannabinoids play a minimal role in the regulation of cardiovascular function in normal conditions, but are altered in most cardiovascular disorders. In shock, endocannabinoids released within blood mediate the associated hypotension through CB(1) activation. In hypertension, there is evidence for changes in the expression of CB(1), and CB(1) antagonism reduces blood pressure in obese hypertensive and diabetic patients. The endocannabinoid system is also upregulated in cardiac pathologies. This is likely to be cardioprotective, via CB(2) and CB(1) (lesser extent). In the vasculature, endocannabinoids cause vasorelaxation through activation of multiple target sites, inhibition of calcium channels, activation of potassium channels, NO production and the release of vasoactive substances. Changes in the expression or function of any of these pathways alter the vascular effect of endocannabinoids. Endocannabinoids have positive (CB(2)) and negative effects (CB(1)) on the progression of atherosclerosis. However, any negative effects of CB(1) may not be consequential, as chronic CB(1) antagonism in large scale human trials was not associated with significant reductions in atheroma. In neurovascular disorders such as stroke, endocannabinoids are upregulated and protective, involving activation of CB(1), CB(2), TRPV1 and PPARα. Although most of this evidence is from preclinical studies, it seems likely that cannabinoid-based therapies could be beneficial in a range of cardiovascular disorders.

A review on potential neurotoxicity of titanium dioxide nanoparticles

As the rapid development of nanotechnology in the past three decades, titanium dioxide nanoparticles (TiO2 NPs), for their peculiar physicochemical properties, are widely applied in consumer products, food additives, cosmetics, drug carriers, and so on. However, little is known about their potential exposure and neurotoxic effects. Once NPs are unintentionally exposed to human beings, they could be absorbed, and then accumulated in the brain regions by passing through the blood-brain barrier (BBB) or through the nose-to-brain pathway, potentially leading to dysfunctions of central nerve system (CNS). Besides, NPs may affect the brain development of embryo by crossing the placental barrier. A few in vivo and in vitro researches have demonstrated that the morphology and function of neuronal or glial cells could be impaired by TiO2 NPs which might induce cell necrosis. Cellular components, such as mitochondrial, lysosome, and cytoskeleton, could also be influenced as well. The recognition ability, spatial memory, and learning ability of TiO2 NPs-treated rodents were significantly impaired, which meant that accumulation of TiO2 NPs in the brain could lead to neurodegeneration. However, conclusions obtained from those studies were not consistent with each other as researchers may choose different experimental parameters, including administration ways, dosage, size, and crystal structure of TiO2 NPs. Therefore, in order to fully understand the potential risks of TiO2 NPs to brain health, figure out research areas where further studies are required, and improve its bio-safety for applications in the near future, how TiO2 NPs interact with the brain is investigated in this review by summarizing the current researches on neurotoxicity induced by TiO2 NPs.

Endocannabinoids modulate human blood-brain barrier permeability in vitro

Background and Purpose

Endocannabinoids alter permeability at various epithelial barriers, and cannabinoid receptors and endocannabinoid levels are elevated by stroke, with potential neuroprotective effects. We therefore explored the role of endocannabinoids in modulating blood–brain barrier (BBB) permeability in normal conditions and in an ischaemia/reperfusion model.

Experimental Approach

Human brain microvascular endothelial cell and astrocyte co-cultures modelled the BBB. Ischaemia was modelled by oxygen-glucose deprivation (OGD) and permeability was measured by transepithelial electrical resistance. Endocannabinoids or endocannabinoid-like compounds were assessed for their ability to modulate baseline permeability or OGD-induced hyperpermeability. Target sites of action were investigated using receptor antagonists and subsequently identified with real-time PCR.

Key Results

Anandamide (10 μM) and oleoylethanolamide (OEA, 10 μM) decreased BBB permeability (i.e. increased resistance). This was mediated by cannabinoid CB₂ receptors, transient receptor potential vanilloid 1 (TRPV1) channels, calcitonin gene-regulated peptide (CGRP) receptor (anandamide only) and PPARα (OEA only). Application of OEA, palmitoylethanolamide (both PPARα mediated) or virodhamine (all 10 μM) decreased the OGD-induced increase in permeability during reperfusion. 2-Arachidonoyl glycerol, noladin ether and oleamide did not affect BBB permeability in normal or OGD conditions. N-arachidonoyl-dopamine increased permeability through a cytotoxic mechanism. PPARα and γ, CB₁ receptors, TRPV1 channels and CGRP receptors were expressed in both cell types, but mRNA for CB₂ receptors was only present in astrocytes.

Conclusion and Implication

The endocannabinoids may play an important modulatory role in normal BBB physiology, and also afford protection to the BBB during ischaemic stroke, through a number of target sites.

Cannabinoid Signaling and Neuroinflammatory Diseases: A Melting pot for the Regulation of Brain Immune Responses

The concept of the central nervous system (CNS) as an immune-privileged site, essentially due to the presence of the blood brain barrier, appears to be overly simplistic. Indeed, within healthy CNS immune activities are permitted and are required for neuronal function and host defense, not only due to the presence of the resident innate immune cells of the brain, but also by virtue of a complex cross-talk of the CNS with peripheral immune cells. Nonetheless, long-standing and persisting neuroinflammatory responses are most often detrimental and characterize several neuroinflammatory diseases, including multiple sclerosis, Alzheimer's disease and amyotrophic lateral sclerosis. A growing body of evidence suggests that Cannabis sativa-derived phytocannabinoids, as well as synthetic cannabinoids, are endowed with significant immunoregulatory and anti-inflammatory properties, both in peripheral tissues and in the CNS, through the activation of cannabinoid receptors. In this review, the immunomodulatory effects of cannabinoid signaling on the most relevant brain immune cells will be discussed. In addition, the impact of cannabinoid regulation on the overall integration of the manifold brain immune responses will also be highlighted, along with the implication of these compounds as potential agents for the management of neuroinflammatory disorders.

Endocannabinoids and the Immune System in Health and Disease

Endocannabinoids are bioactive lipids that have the potential to signal through cannabinoid receptors to modulate the functional activities of a variety of immune cells. Their activation of these seven-transmembranal, G protein-coupled receptors sets in motion a series of signal transductional events that converge at the transcriptional level to regulate cell migration and the production of cytokines and chemokines. There is a large body of data that supports a functional relevance for 2-arachidonoylglycerol (2-AG) as acting through the cannabinoid receptor type 2 (CB2R) to inhibit migratory activities for a diverse array of immune cell types. However, unequivocal data that supports a functional linkage of anandamide (AEA) to a cannabinoid receptor in immune modulation remains to be obtained. Endocannabinoids, as typical bioactive lipids, have a short half-life and appear to act in an autocrine and paracrine fashion. Their immediate effective action on immune function may be at localized sites in the periphery and within the central nervous system. It is speculated that endocannabinoids play an important role in maintaining the overall "fine-tuning" of the immune homeostatic balance within the host.

Anandamide rescues retinal barrier properties in Müller glia through nitric oxide regulation

The blood retinal barrier (BRB) can mitigate deleterious immune response. Dysfunction at the BRB can affect disease progression. Under inflammatory conditions Müller glia produce increased pro-inflammatory factors, like nitric oxide (NO). In this study we describe molecular events at the Müller glia during inflammation which could affect inner BRB properties. Griess assay and 4,5-diaminofluorescein diacetate (DAF-2DA) time-lapse fluorescence were used to measure NO production. Western blot was used to analyze the expression of inducible nitric oxide synthase (iNOS) and mitogen-activated protein kinases (MAPK) components. Lucifer Yellow was used to measure permeability. Griess assay and DAF-2DA time-lapse fluorescence images revealed that lipopolysaccharide (LPS) induced inflammation and increased NO production. In parallel, changes were observed in tight junction proteins, zona occludens 1 (ZO-1), connexin 43 (Cx43), and permeability. This was mediated through activation of iNOS and mitogen-activated protein kinase phosphatase-1 (MKP-1), implicated in immune response. Endocannabinoids can exert a protective and anti-inflammatory effect. Exogenous arachidonoyl ethanolamide (AEA) inhibited NO generation and also abolished LPS-induced increase in permeability. Our work suggests that subtle changes in Müller glia function, which act as part of the BRB, could contribute to retinal health. AEA which can reduce inflammatory cytotoxicity has potential as treatment in several ocular manifestations where the integrity of the BRB is crucial.

West Nile virus-induced cell adhesion molecules on human brain microvascular endothelial cells regulate leukocyte adhesion and modulate permeability of the in vitro blood-brain barrier model

Characterizing the mechanisms by which West Nile virus (WNV) causes blood-brain barrier (BBB) disruption, leukocyte infiltration into the brain and neuroinflammation is important to understand the pathogenesis of WNV encephalitis. Here, we examined the role of endothelial cell adhesion molecules (CAMs) in mediating the adhesion and transendothelial migration of leukocytes across human brain microvascular endothelial cells (HBMVE). Infection with WNV (NY99 strain) significantly induced ICAM-1, VCAM-1, and E-selectin in human endothelial cells and infected mice brain, although the levels of their ligands on leukocytes (VLA-4, LFA-1and MAC-1) did not alter. The permeability of the in vitro BBB model increased dramatically following the transmigration of monocytes and lymphocytes across the models infected with WNV, which was reversed in the presence of a cocktail of blocking antibodies against ICAM-1, VCAM-1, and E-selectin. Further, WNV infection of HBMVE significantly increased leukocyte adhesion to the HBMVE monolayer and transmigration across the infected BBB model. The blockade of these CAMs reduced the adhesion and transmigration of leukocytes across the infected BBB model. Further, comparison of infection with highly neuroinvasive NY99 and non-lethal (Eg101) strain of WNV demonstrated similar level of virus replication and fold-increase of CAMs in HBMVE cells suggesting that the non-neuropathogenic response of Eg101 is not because of its inability to infect HBMVE cells. Collectively, these results suggest that increased expression of specific CAMs is a pathological event associated with WNV infection and may contribute to leukocyte infiltration and BBB disruption in vivo. Our data further implicate that strategies to block CAMs to reduce BBB disruption may limit neuroinflammation and virus-CNS entry via 'Trojan horse' route, and improve WNV disease outcome.

Functions of the CB1 and CB 2 receptors in neuroprotection at the level of the blood-brain barrier

The cannabinoid (CB) receptors are the main targets of the cannabinoids, which include plant cannabinoids, endocannabinoids and synthetic cannabinoids. Over the last few years, accumulated evidence has suggested a role of the CB receptors in neuroprotection. The blood-brain barrier (BBB) is an important brain structure that is essential for neuroprotection. A link between the CB receptors and the BBB is thus likely, but this possible connection has only recently gained attention. Cannabinoids and the BBB share the same mechanisms of neuroprotection and both protect against excitotoxicity (CB1), cell death (CB1), inflammation (CB2) and oxidative stress (possibly CB independent)-all processes that also damage the BBB. Several examples of CB-mediated protection of the BBB have been found, such as inhibition of leukocyte influx and induction of amyloid beta efflux across the BBB. Moreover, the CB receptors were shown to improve BBB integrity, particularly by restoring the tightness of the tight junctions. This review demonstrated that both CB receptors are able to restore the BBB and neuroprotection, but much uncertainty about the underlying signaling cascades still exists and further investigation is needed.

Reduced immune cell infiltration and increased pro-inflammatory mediators in the brain of Type 2 diabetic mouse model infected with West Nile virus

Background

Diabetes is a significant risk factor for developing West Nile virus (WNV)-associated encephalitis (WNVE) in humans, the leading cause of arboviral encephalitis in the United States. Using a diabetic mouse model (db/db), we recently demonstrated that diabetes enhanced WNV replication and the susceptibility of mice to WNVE. Herein, we have examined immunological events in the brain of wild type (WT) and db/db mice after WNV infection. We hypothesized that WNV-induced migration of protective leukocytes into the brain is attenuated in the presence of diabetes, leading to a high viral load in the brain and severe disease in diabetic mice.

Methods

Nine-week old C57BL/6 WT and db/db mice were infected with WNV. Leukocyte infiltration, expression of cell adhesion molecules (CAM), neuroinflammatory responses, activation of astrocytes, and neuronal death were analyzed using immunohistochemistry, qRT-PCR, flow cytometry, and western blot.

Results

We demonstrate that infiltration of CD45⁺ leukocytes and CD8⁺T cells was significantly reduced in the brains of db/db mice, which was correlated with attenuated expression of CAM such as E-selectin and ICAM-1. WNV infection in db/db mice was associated with an enhanced inflammatory response in the brain. mRNA and protein levels of key chemokines such as CXCL10, CXCL1, CCL2, CCL5, CCL3, and G-CSF, and cytokines such as IL-1β, TNF, IL-6, IFNγ, and IL-1α were significantly elevated in the brains of db/db mice compared to WT mice. Elevated levels of cytokines also correlated with increased astrocytes activation and neuronal damage in the brains of db/db mice.

Conclusion

These data suggest that reduced leukocytes recruitment, in part, due to lower levels of CAM results in failure to clear WNV infection from the brain leading to increased production of inflammatory molecules, which mediates increased neuronal death and mortality in db/db mice. This is the first study to elucidate the expression of CAM and their correlation with the migration of leukocytes, specifically cytotoxic CD8⁺ T cells, in increasing disease severity in the diabetic mouse model.

Targeting endothelial CD146 attenuates neuroinflammation by limiting lymphocyte extravasation to the CNS

The ability to selectively block the entry of leukocytes into the central nervous system (CNS) without compromising the immune system is an attractive therapeutic approach for treating multiple sclerosis (MS). Using endothelial CD146-deficienct mice as a MS model, we found that endothelial CD146 plays an active role in the CNS-directed extravasation of encephalitogenic T cells, including CD146⁺ T_H1 and T_H17 lymphocytes. Moreover, treating both active and passive MS models with the anti-CD146 antibody AA98 significantly decreased the infiltrated lymphocytes in the CNS and decreased neuroinflammation. Interestingly, the ability of AA98 to inhibit the migration of CD146⁺ lymphocytes was dependent on targeting endothelial CD146, but not lymphocytic CD146. These results suggest a key molecular target located on the blood-brain barrier endothelium that mediates the extravasation of inflammatory cells into the CNS. In addition, our data suggest that the AA98 is a promising candidate for treating MS and other CNS autoimmune diseases.

Platelet-derived growth factor BB mediates the glioma-induced migration of bone marrow-derived mesenchymal stem cells by promoting the expression of vascular cell adhesion molecule-1 through the PI3K, P38 MAPK and NF-κB pathways

Platelet-derived growth factor BB (PDGFBB) has been shown to activate the migration of bone marrow-derived mesenchymal stem cells (BM-MSCs), and to contribute to mediating the tropism of BM-MSCs towards gliomas. However, the exact mechanism of this migratory behavior remains to be elucidated. The present study investigated the role of vascular cell adhesion molecule-1 (VCAM-1) in the PDGFBB-induced migration of BM-MSCs, the effect of PDGFBB on VCAM-1 expression of BM-MSCs and related signaling pathways involved in this process. Rat BM-MSCs were isolated and cultured by their characteristics of adherence to plastics. The concentrations of PDGFBB in the conditioned medium of C6 and U87 cells were measured using the ELISA method. In vitro migration assays using a VCAM-1 blocking antibody were performed to evaluate the role of VCAM-1 in PDGFBB-induced migration of BM-MSCs. The effect of rat recombinant PDGFBB on VCAM-1 expression of BM-MSCs was studied by RT-PCR and western blotting. LY294002, SB203580, PD98059, SP600125 and BAY11-7082 were used to explore the role of PI3K, p38 MAPK, MEK, JNK and NF-κB in the related intracellular signal transduction of PDGFBB stimulation on VCAM-1 expression of BM-MSCs. The data demonstrated that the neutralization of VCAM-1 inhibited the migration of BM-MSCs induced by PDGFBB. Additionally, PDGFBB stimulation increased VCAM-1 expression of BM-MSCs, which could be inhibited by LY294002, SB203580 and BAY11-7082. It is reasonable to conclude that PDGFBB significantly enhanced the expression of VCAM-1 in BM-MSCs, which facilitated the migration of BM-MSCs towards PDGFBB. PI3K, p38 MAPK and NF-κB were involved in the signal transduction of this process.

Cannabinoid modulation of neuroinflammatory disorders

In recent years, a growing interest has been dedicated to the study of the endocannabinoid system. The isolation of Cannabis sativa main psychotropic compound, Δ(9)-tetrahydrocannabinol (THC), has led to the discovery of an atypical neurotransmission system that modulates the release of other neurotransmitters and participates in many biological processes, including the cascade of inflammatory responses. In this context, cannabinoids have been studied for their possible therapeutic properties in neuroinflammatory diseases. In this review, historic and biochemical aspects of cannabinoids are discussed, as well as their function as modulators of inflammatory processes and therapeutic perspectives for neurodegenerative disorders, particularly, multiple sclerosis.