The blood-brain barrier and immune function and dysfunction

Contribution of Oxidative Stress and Inflammation to the Neurogenic Hypertension Induced by Intermittent Hypoxia

Chronic intermittent hypoxia (CIH), the hallmark of obstructive sleep apnea, is the main risk factor to develop systemic hypertension. Oxidative stress, inflammation, and sympathetic overflow have been proposed as possible mechanisms underlying the CIH-induced hypertension. CIH potentiates the carotid body (CB) chemosensory discharge leading to sympathetic overflow, autonomic dysfunction, and hypertension. Oxidative stress and pro-inflammatory molecules are involved in neurogenic models of hypertension, acting on brainstem and hypothalamic nuclei related to the cardiorespiratory control, such as the nucleus of the solitary tract, which is the primary site for the afferent inputs from the CB. Oxidative stress and pro-inflammatory molecules contribute to the activation of the CB chemoreflex pathway in CIH-induced hypertension. In this brief review, we will discuss new evidence for a critical role of oxidative stress and neuro-inflammation in development of the CIH-induced hypertension through activation of the CB chemoreflex pathway.

Biological Mechanisms of Cancer-Induced Depression

Patients with cancer are more likely to develop depression than the general population, which negatively impacts their quality of life and prognosis. In order to identify effective antidepressants catered toward cancer patients, the biology of depression in the context of cancer must be well-understood. Many theories have emerged postulating the mechanisms underlying the development of depressive disorder. Here, we review the role inflammation, a hyperactive hypothalamic-pituitary-adrenal (HPA) axis, and glutamate excitotoxicity may play in cancer-induced depression. Hopefully, novel therapeutics targeting these dysregulated pathways may be potent in ameliorating depressive symptoms in the cancer population.

Evaluation of the neutrophil/lymphocyte ratio, platelet/lymphocyte ratio, and mean platelet volume as inflammatory markers in children with attention-deficit hyperactivity disorder

AIM

The neutrophil/lymphocyte ratio (NLR), platelet/lymphocyte ratio (PLR), monocyte/lymphocyte ratio (MLR), and mean platelet volume (MPV) have recently been used as indicators of a systemic inflammatory response. The aim of this study was to investigate the relations of the NLR, PLR, MLR, and MPV with attention-deficit hyperactivity disorder (ADHD).

METHODS

The study group consisting of 82 children diagnosed with ADHD was compared with a healthy control (HC) group of 70 age-, sex-, and body-mass-index-matched subjects. The NLR, PLR, MLR, and MPV were measured according to the complete blood count.

RESULTS

The NLR, PLR, MLR, MPV, and neutrophil count of the ADHD group were significantly higher than those of the HC group. The lymphocyte counts of the patients were significantly lower than those of the HC group.

CONCLUSION

Inflammation might play a role in the etiopathogenesis of ADHD. The NLR, PLR, MLR, and MPV may be potential inflammation markers for ADHD in children.

Thrombin Inhibition Reduces the Expression of Brain Inflammation Markers upon Systemic LPS Treatment

Systemic inflammation and brain pathologies are known to be linked. In the periphery, the inflammation and coagulation systems are simultaneously activated upon diseases and infections. Whether this well-established interrelation also counts for neuroinflammation and coagulation factor expression in the brain is still an open question. Our aim was to study whether the interrelationship between coagulation and inflammation factors may occur in the brain in the setting of systemic inflammation. The results indicate that systemic injections of lipopolysaccharide (LPS) upregulate the expression of both inflammatory and coagulation factors in the brain. The activity of the central coagulation factor thrombin was tested by a fluorescent method and found to be significantly elevated in the hippocampus following systemic LPS injection (0.5 ± 0.15 mU/mg versus 0.2 ± 0.03 mU/mg in the control). A panel of coagulation factors and effectors (such as thrombin, FX, PAR1, EPCR, and PC) was tested in the hippocampus, isolated microglia, and N9 microglia cell by Western blot and real-time PCR and found to be modulated by LPS. One central finding is a significant increase in FX expression level following LPS induction both in vivo in the hippocampus and in vitro in N9 microglia cell line (5.5 ± 0.6- and 2.3 ± 0.1-fold of increase, resp.). Surprisingly, inhibition of thrombin activity (by a specific inhibitor NAPAP) immediately after LPS injection results in a reduction of both the inflammatory (TNFα, CXL9, and CCL1; p < 0.006) and coagulation responses (FX and PAR1; p < 0.004) in the brain. We believe that these results may have a profound clinical impact as they might indicate that reducing coagulation activity in the setting of neurological diseases involving neuroinflammation may improve disease outcome and survival.

Microbiome-Gut-Brain Axis and Toll-Like Receptors in Parkinson's Disease

Parkinson’s disease (PD) is a progressively debilitating neurodegenerative disease characterized by α-synucleinopathy, which involves all districts of the brain-gut axis, including the central, autonomic and enteric nervous systems. The highly bidirectional communication between the brain and the gut is markedly influenced by the microbiome through integrated immunological, neuroendocrine and neurological processes. The gut microbiota and its relevant metabolites interact with the host via a series of biochemical and functional inputs, thereby affecting host homeostasis and health. Indeed, a dysregulated microbiota-gut-brain axis in PD might lie at the basis of gastrointestinal dysfunctions which predominantly emerge many years prior to the diagnosis, corroborating the theory that the pathological process is spread from the gut to the brain. Toll-like receptors (TLRs) play a crucial role in innate immunity by recognizing conserved motifs primarily found in microorganisms and a dysregulation in their signaling may be implicated in α-synucleinopathy, such as PD. An overstimulation of the innate immune system due to gut dysbiosis and/or small intestinal bacterial overgrowth, together with higher intestinal barrier permeability, may provoke local and systemic inflammation as well as enteric neuroglial activation, ultimately triggering the development of alpha-synuclein pathology. In this review, we provide the current knowledge regarding the relationship between the microbiota-gut⁻brain axis and TLRs in PD. A better understanding of the dialogue sustained by the microbiota-gut-brain axis and innate immunity via TLR signaling should bring interesting insights in the pathophysiology of PD and provide novel dietary and/or therapeutic measures aimed at shaping the gut microbiota composition, improving the intestinal epithelial barrier function and balancing the innate immune response in PD patients, in order to influence the early phases of the following neurodegenerative cascade.

Early food allergy and respiratory allergy symptoms and attention-deficit/hyperactivity disorder in Chinese children: A cross-sectional study

BACKGROUND

The relationship between food allergy and respiratory allergy and attention-deficit/hyperactivity disorder (ADHD) in children is rarely investigated. The objective of this study was to determine whether early food allergy and respiratory allergy symptoms are associated with the prevalence of ADHD in Chinese school-age children.

METHODS

This cross-sectional study was conducted in school-age children using cluster-stratified methods from 9 cities across China between November and December 2005. A family and social environmental questionnaire including the diagnosis history of ADHD and allergic diseases (food allergy, allergic rhinitis, and bronchial asthma), as well as general information, was completed by parents.

RESULTS

The prevalence of both allergic rhinitis (20.4%) and asthma (11.6%) in the food allergy group was significantly higher than in the non-food allergy group (9.0% and 2.8%, respectively; both P < .001). The multivariable analysis showed that single food allergy (OR = 1.53, 95% CI: 1.13-2.05, P = .005), food allergy complicated with allergic rhinitis or asthma (OR = 3.36, 95% CI: 2.19-5.14, P < .001), and food allergy complicated with allergic rhinitis and asthma simultaneously (OR = 4.08, 95% CI: 2.05-8.11, P < .001) were independently associated with the increased risk of ADHD.

CONCLUSIONS

Early food allergy is associated with ADHD in school-age children. Early food allergy and respiratory allergy symptoms independently and synergistically contributed to higher risk of ADHD. Monitoring food allergy in early life could help in the early prediction and intervention for the consequent allergy march and ADHD in children.

Acute intermittent hypoxia and rehabilitative training following cervical spinal injury alters neuronal hypoxia- and plasticity-associated protein expression

One of the most promising approaches to improve recovery after spinal cord injury (SCI) is the augmentation of spontaneously occurring plasticity in uninjured neural pathways. Acute intermittent hypoxia (AIH, brief exposures to reduced O₂ levels alternating with normal O₂ levels) initiates plasticity in respiratory systems and has been shown to improve recovery in respiratory and non-respiratory spinal systems after SCI in experimental animals and humans. Although the mechanism by which AIH elicits its effects after SCI are not well understood, AIH is known to alter protein expression in spinal neurons in uninjured animals. Here, we examine hypoxia- and plasticity-related protein expression using immunofluorescence in spinal neurons in SCI rats that were treated with AIH combined with motor training, a protocol which has been demonstrated to improve recovery of forelimb function in this lesion model. Specifically, we assessed protein expression in spinal neurons from animals with incomplete cervical SCI which were exposed to AIH treatment + motor training either for 1 or 7 days. AIH treatment consisted of 10 episodes of AIH: (5 min 11% O₂: 5 min 21% O₂) for 7 days beginning at 4 weeks post-SCI. Both 1 or 7 days of AIH treatment + motor training resulted in significantly increased expression of the transcription factor hypoxia-inducible factor-1α (HIF-1α) relative to normoxia-treated controls, in neurons both proximal (cervical) and remote (lumbar) to the SCI. All other markers examined were significantly elevated in the 7 day AIH + motor training group only, at both cervical and lumbar levels. These markers included vascular endothelial growth factor (VEGF), brain-derived neurotrophic factor (BDNF), and phosphorylated and nonphosphorylated forms of the BDNF receptor tropomyosin-related kinase B (TrkB). In summary, AIH induces plasticity at the cellular level after SCI by altering the expression of major plasticity- and hypoxia-related proteins at spinal regions proximal and remote to the SCI. These changes occur under the same AIH protocol which resulted in recovery of limb function in this animal model. Thus AIH, which induces plasticity in spinal circuitry, could also be an effective therapy to restore motor function after nervous system injury.

White matter pathways as both a target and mediator of health behaviors

Health behaviors arise from the dynamics of highly interconnected networks in the brain and variability in these networks drives individual differences in behavior. In this review, we show how many factors that predict the physical health of the body also correlate with variability of the myelinated fascicles, called white matter, that connect brain regions together. The general pattern present in the literature is that as predictors of physical health decline, there is often a coincident reduction in the integrity of major white matter pathways. We also highlight a plausible mechanism, inflammatory pathways, whereby health-related activation of the immune system can impact the myelin sheath, a protective tissue that facilitates long range communication in the brain. The growing body of evidence supports the hypothesis that degrading health in the periphery may disrupt the communication efficiency of the macroscopic neural circuits that mediate complex behaviors, which can in turn contribute to poorer physical health.

Susceptibility of Primary Human Choroid Plexus Epithelial Cells and Meningeal Cells to Infection by JC Virus

JC polyomavirus (JCPyV) establishes a lifelong persistence in roughly half the human population worldwide. The cells and tissues that harbor persistent virus in vivo are not known, but renal tubules and other urogenital epithelial cells are likely candidates as virus is shed in the urine of healthy individuals. In an immunosuppressed host, JCPyV can become reactivated and cause progressive multifocal leukoencephalopathy (PML), a fatal demyelinating disease of the central nervous system. Recent observations indicate that JCPyV may productively interact with cells in the choroid plexus and leptomeninges. To further study JCPyV infection in these cells, primary human choroid plexus epithelial cells and meningeal cells were challenged with virus, and their susceptibility to infection was compared to the human glial cell line, SVG-A. We found that JCPyV productively infects both choroid plexus epithelial cells and meningeal cells in vitro Competition with the soluble receptor fragment LSTc reduced virus infection in these cells. Treatment of cells with neuraminidase also inhibited both viral infection and binding. Treatment with the serotonin receptor antagonist, ritanserin, reduced infection in SVG-A and meningeal cells. We also compared the ability of wild-type and sialic acid-binding mutant pseudoviruses to transduce these cells. Wild-type pseudovirus readily transduced all three cell types, but pseudoviruses harboring mutations in the sialic acid-binding pocket of the virus failed to transduce the cells. These data establish a novel role for choroid plexus and meninges in harboring virus that likely contributes not only to meningoencephalopathies but also to PML.IMPORTANCE JCPyV infects greater than half the human population worldwide and causes central nervous system disease in patients with weakened immune systems. Several recent reports have found JCPyV in the choroid plexus and leptomeninges of patients with encephalitis. Due to their role in forming the blood-cerebrospinal fluid barrier, the choroid plexus and leptomeninges are also poised to play roles in virus invasion of brain parenchyma, where infection of macroglial cells leads to the development of progressive multifocal leukoencephalopathy, a severely debilitating and often fatal infection. In this paper we show for the first time that primary choroid plexus epithelial cells and meningeal cells are infected by JCPyV, lending support to the association of JCPyV with meningoencephalopathies. These data also suggest that JCPyV could use these cells as reservoirs for the subsequent invasion of brain parenchyma.

Lipopolysaccharide Associates with Amyloid Plaques, Neurons and Oligodendrocytes in Alzheimer's Disease Brain: A Review

This review proposes that lipopolysaccharide (LPS, found in the wall of all Gram-negative bacteria) could play a role in causing sporadic Alzheimer’s disease (AD). This is based in part upon recent studies showing that: Gram-negative E. coli bacteria can form extracellular amyloid; bacterial-encoded 16S rRNA is present in all human brains with over 70% being Gram-negative bacteria; ultrastructural analyses have shown microbes in erythrocytes of AD patients; blood LPS levels in AD patients are 3-fold the levels in control; LPS combined with focal cerebral ischemia and hypoxia produced amyloid-like plaques and myelin injury in adult rat cortex. Moreover, Gram-negative bacterial LPS was found in aging control and AD brains, though LPS levels were much higher in AD brains. In addition, LPS co-localized with amyloid plaques, peri-vascular amyloid, neurons, and oligodendrocytes in AD brains. Based upon the postulate LPS caused oligodendrocyte injury, degraded Myelin Basic Protein (dMBP) levels were found to be much higher in AD compared to control brains. Immunofluorescence showed that the dMBP co-localized with β amyloid (Aβ) and LPS in amyloid plaques in AD brain, and dMBP and other myelin molecules were found in the walls of vesicles in periventricular White Matter (WM). These data led to the hypothesis that LPS acts on leukocyte and microglial TLR4-CD14/TLR2 receptors to produce NFkB mediated increases of cytokines which increase Aβ levels, damage oligodendrocytes and produce myelin injury found in AD brain. Since Aβ_1–42 is also an agonist for TLR4 receptors, this could produce a vicious cycle that accounts for the relentless progression of AD. Thus, LPS, the TLR4 receptor complex, and Gram-negative bacteria might be treatment or prevention targets for sporadic AD.

Assessing long-term neuroinflammatory responses to encephalopathy using MRI approaches in a rat endotoxemia model

Sepsis-associated encephalopathy (SAE) induces neuroinflammation, which is associated with cognitive impairment (CI). CI is also correlated with aging. We used contrast-enhanced magnetic resonance imaging (MRI), perfusion MRI, and MR spectroscopy to assess long-term alterations in BBB permeability, microvascularity, and metabolism, respectively, in a rat lipopolysaccharide-induced SAE model. Free radical-targeted molecular MRI was used to detect brain radical levels at 24 h and 1 week post-LPS injection. CE-MRI showed increased Gd-DTPA uptake in LPS rat brains at 24 h in cerebral cortex, hippocampus, thalamus, and perirhinal cortex regions. Increased MRI signal intensities were observed in LPS rat brains in cerebral cortex, perirhinal cortex, and hippocampus regions 1 week post-LPS. Long-term BBB dysfunction was detected in the cerebral cortex at 6 weeks post-LPS. Increased relative cerebral blood flow (rCBF) in cortex and thalamus regions at 24 h, decreased cortical and hippocampal rCBF at 6 weeks, decreased cortical rCBF at 3 and 12 weeks, and increased thalamus rCBF at 6 weeks post-LPS, were detected. MRS indicated that LPS-exposed rat brains had decreased: NAA/Cho metabolite ratios at 1, 3, 6, and 12 weeks; Cr/Cho at 1, 3, and 12 weeks; and Myo-Ins/Cho at 1, 3, and 6 weeks post-LPS. Free radical imaging detected increased radical levels in LPS rat brains at 24 h and 1 week post-LPS. LPS-exposed rats were compared to saline-treated controls. We clearly demonstrated BBB dysfunction, impaired vascularity, and decreased brain metabolites, as measures of long-term neuroinflammatory indicators, as well as increased free radicals in a LPS-induced rat SAE model.

Neuroimmune Biomarkers in Mental Illness

Exploration of neuroimmune mechanisms is vital to the understanding of the pathogenesis and pathophysiology of mental disorders. Inflammatory and immune mechanisms are increasingly understood to underpin a number of neuropsychiatric disorders, with an ever-expanding evidence base drawn from basic science to large-scale epidemiological data. Unravelling of these mechanisms should lead to biomarker discovery and potential new avenues for therapeutics that modulate immunological mechanisms. Identification of neuroimmune biomarkers is vital to improving diagnosis, stratification and treatment of mental disorders. There is an urgent clinical need for new therapeutic approaches with poor treatment response and treatment resistance a major problem for many psychiatric disorders including depression and schizophrenia. Neurodegenerative psychiatric disorders such as Alzheimer's also have clear neuroimmune underpinnings and manifest an urgent clinical need for improvements in diagnosis and research towards transformative disease-modifying treatments. This chapter provides some background on the role of the neuroimmune system in mental illness, exploring the role for biomarkers, in addition to reviewing the current state of knowledge in this exciting field. We also reflect on the inherent challenges and methodological pitfalls faced by research in this field, including the complexity of conceptualising multidimensional mental disorders and the dynamic shifting sands of the immune system.

A noradrenergic lesion aggravates the effects of systemic inflammation on the hippocampus of aged rats

Neuroinflammation is potentiated by early degeneration of the locus coeruleus noradrenergic pathway (LC-NE) commonly seen in aging-related neurodegenerative diseases such as Alzheimer’s disease and Parkinson’s disease. In animal models, lipopolysaccharide (LPS) induces strong peripheral immune responses that can cause cognitive changes secondary to neuroinflammation. The influence of the peripheral immune response on cognition might be exacerbated by LC-NE degeneration, but this has not been well characterized previously. In this study, we investigated how systemic inflammation affects neuroinflammation and cognition in aged rats that have had either normal or damaged LC-NE transmitter systems. Rats were first exposed to the selective noradrenergic (NE) neurotoxin N-(2-chloroethyl)-N-ethyl-2-bromobenzylamine (DSP4) to induce degeneration of central NE pathways. Two weeks later, the rats received a low dose of LPS. This resulted in 3 treatment groups (Control, LPS-, and DSP4+LPS-treated rats) studied at 4 hours (short-term subgroup) and 7 days (long-term subgroup) following the LPS injection. DSP4+LPS-treated rats exhibited increased serum levels of several pro-inflammatory cytokines, increased astroglial and microglial activation in the hippocampus, and poorer performance in the novel object recognition task (NORT) compared to controls and LPS-treated rats. Additionally, serum and brain tissue levels of brain-derived neurotrophic factor (BDNF) were modulated over time in the DSP4+LPS group compared to the other two groups. Specifically, DSP4+LPS-treated rats in the short-term subgroup had lower hippocampal BDNF levels (~25%) than controls and LPS-treated rats, which negatively correlated with hippocampal astrogliosis and positively correlated with hippocampal IL-1β levels. Serum and hippocampal BDNF levels in the DSP4+LPS-treated rats in the long-term subgroup returned to levels similar to the control group. These results show that systemic inflammation in LC-NE-lesioned aged rats promotes an exacerbated systemic and central inflammatory response compared to LC-NE-intact rats and alters BDNF levels, indicating the important role of this neurotransmitter system in response to neuroinflammation.

IL-33 Provides Neuroprotection through Suppressing Apoptotic, Autophagic and NF-κB-Mediated Inflammatory Pathways in a Rat Model of Recurrent Neonatal Seizure

Interleukin-33 (IL-33) is a novel identified chromatin-associated cytokine of IL-1 family cytokines. It signals through a heterodimer comprised of ST2L and IL-1RAcp, and plays a crucial role in many diseases. However, very little is known about the role and underlying intricate mechanisms of IL-33 in recurrent neonatal seizure (RNS). To determine whether IL-33 plays an important regulatory role, we established a neonatal seizure model in this study. Rats were subjected to recurrent seizures induced by inhaling volatile flurothyl. Recombinant IL-33 or PBS were also administered by intraperitoneally (IP) before surgery, respectively. Here, our current results indicated that RNS contributed to a significant reduction in IL-33 and its specific receptor (ST2L) expressions in cortex. While, in hippocampus, RNS induced an increase in IL-33 and ST2L evidently, compared with Sham group. After injection with IL-33, however, a remarkable increase in total IL-33 was detected both in brain cortex and hippocampus. In addition, IL-33 was mainly co-localized in the nuclear of GFAP⁺ astrocytes and the cytoplasm of the Iba-1⁺ microglia and IL-33⁺/NeuN⁺ merged cells. In parallel, ST2L was expressed mainly in the membrane of GFAP⁺ astrocytes, Iba-1⁺ microglia and NeuN⁺ neurons, respectively. Furthermore, administration of IL-33 improved RNS-induced behavioral deficits, promoted bodyweight gain, and ameliorated spatial learning and memory ability. Moreover, IL-33 pretreatment blocked the activation of NF-κB, resisted inflammatory cytokines IL-1β and TNF-α increase, as well as suppressed apoptosis and autophagy activation after RNS. Collectively, IL-33 provides potential neuroprotection through suppressing apoptosis, autophagy and at least in part by NF-κB-mediated inflammatory pathways after RNS.

Novel biomarkers of metabolic dysfunction is autism spectrum disorder: potential for biological diagnostic markers

Autism spectrum disorder (ASD) is a neurodevelopmental disorder that is behaviorally defined by social and communication impairments and restricted interests and repetitive behaviors. There is currently no biomarkers that can help in the diagnosis. Several studies suggest that mitochondrial dysfunction is commonly involved in ASD pathophysiology, but standard mitochondrial biomarkers are thought to be very variable. In the present study we examine a wide variety of plasma biomarkers of mitochondrial metabolism and the related abnormalities of oxidative stress and apoptosis in 41 ASD patients assessed for ASD severity using the Childhood Autism Rating Scales and 41 non-related age and sex matched healthy controls. Our findings confirm previous studies indicating abnormal mitochondrial and related biomarkers in children with ASD including pyruvate, creatine kinase, Complex 1, Glutathione S-Transferase, glutathione and Caspase 7. As a novel finding, we report that lactate dehydrogenase is abnormal in children with ASD. We also identified that only the most severe children demonstrated abnormalities in Complex 1 activity and Glutathione S-Transferase. Additionally, we find that several biomarkers could be candidates for differentiating children with ASD and typically developing children, including Caspase 7, gluthatione and Glutathione S-Transferase by themselves and lactate dehydrogenase and Complex I when added to other biomarkers in combination. Caspase 7 was the most discriminating biomarker between ASD patients and healthy controls suggesting its potential use as diagnostic marker for the early recognition of ASD pathophysiology. This study confirms that several mitochondrial biomarkers are abnormal in children with ASD and suggest that certain mitochondrial biomarkers can differentiate between ASD and typically developing children, making them possibly useful as a tool to diagnosis ASD and identify ASD subgroups.

Microbes Tickling Your Tummy: the Importance of the Gut-Brain Axis in Parkinson's Disease

Purpose of Review

Patients suffering from Parkinson's disease (PD) are known to experience gastrointestinal dysfunction that might precede the onset of motor symptoms by several years. Evidence suggests an important role of the gut-brain axis in PD pathogenesis. These interactions might be essentially influenced by the gut microbiota. Here, we review recent findings supporting that changes in the gut microbiota composition might be a trigger for inflammation contributing to neurodegeneration in PD.

Recent Findings

Recent research revealed that PD patients exhibit a pro-inflammatory microbiota profile in their intestinal tract that might increase gut permeability, allowing leakage of bacterial products and inflammatory mediators from the intestines. Evidence in literature indicates that alpha-synuclein deposition might start in the enteric nervous system by pro-inflammatory immune activity and then propagates to the CNS. Alternatively, the peripheral inflammatory response could impact the brain through systemic mechanisms.

Summary

A better understanding of the gut-brain interactions and the role of the intestinal microbiota in the regulation of immune responses might bring new insights in PD pathological progression and might lead to novel diagnostics and therapeutic approaches.

Glial and neuroinflammatory targets for treating substance use disorders

BACKGROUND

The plenary session at the 2016 Behavior, Biology and Chemistry: Translational Research in Addiction Conference focused on glia as potential players in the development, persistence and treatment of substance use disorders. Glia partake in various functions that are important for healthy brain activity. Drugs of abuse alter glial cell activity producing several perturbations in brain function that are thought to contribute to behavioral changes associated with substance use disorders. Consequently, drug-induced changes in glia-driven processes in the brain represent potential targets for pharmacotherapeutics treating substance use disorders.

METHODS

Four speakers presented preclinical and clinical research illustrating the effects that glial modulators have on abuse-related behavioral effects of psychostimulants and opioids. This review highlights some of these findings and expands its focus to include other research focused on drug-induced glia abnormalities and glia-focused treatment approaches in substance use disorders.

RESULTS

Preclinical findings show that drugs of abuse induce neuroinflammatory signals and disrupt glutamate homeostasis through their interaction with microglia and astrocytes. Preclinical and clinical studies testing the effects of glial modulators show general effectiveness in reducing behaviors associated with substance use disorders.

CONCLUSIONS

The contribution of drug-induced glial activity continues to emerge as an intriguing target for substance use disorder treatments. Clinical investigations of glial modulators have yielded promising results on substance use measures and indicate that they are generally safe and well-tolerated. However, results have not been entirely positive and more questions remain for continued exploration in the development and testing of glial-directed treatments for substance use disorders.

Bipolar Disorder and Immune Dysfunction: Epidemiological Findings, Proposed Pathophysiology and Clinical Implications

Bipolar disorder (BD) is strongly associated with immune dysfunction. Replicated epidemiological studies have demonstrated that BD has high rates of inflammatory medical comorbidities, including autoimmune disorders, chronic infections, cardiovascular disease and metabolic disorders. Cytokine studies have demonstrated that BD is associated with chronic low-grade inflammation with further increases in pro-inflammatory cytokine levels during mood episodes. Several mechanisms have been identified to explain the bidirectional relationship between BD and immune dysfunction. Key mechanisms include cytokine-induced monoamine changes, increased oxidative stress, pathological microglial over-activation, hypothalamic-pituitary-adrenal (HPA) axis over-activation, alterations of the microbiome-gut-brain axis and sleep-related immune changes. The inflammatory-mood pathway presents several potential novel targets in the treatment of BD. Several proof-of-concept clinical trials have shown a positive effect of anti-inflammatory agents in the treatment of BD; however, further research is needed to determine the clinical utility of these treatments. Immune dysfunction is likely to only play a role in a subset of BD patients and as such, future clinical trials should also strive to identify which specific group(s) of BD patients may benefit from anti-inflammatory treatments.

Cell-penetrating interactomic inhibition of nuclear factor-kappa B in a mouse model of postoperative cognitive dysfunction

Some patients experience impaired cognitive functioning after surgery, a phenomenon referred to as postoperative cognitive dysfunction (POCD). Signs of POCD are closely associated with the development of systemic or hippocampal inflammation. However, the precise pathophysiological mechanisms of prevention/treatment options for POCD still remain unclear. After injury, the transcriptional factor nuclear factor-kappa B (NF-κB) is thought to regulate or stimulate inflammation amplification. Therefore, we designed a cell-penetrating fusion protein called nt-p65-TMD, which inhibits NF-κB p65 activation by translocating into the nucleus. In the present study, we discovered that nt-p65-TMD exerted effects on surgery-induced cognitive impairment in mice. Specifically, nt-p65-TMD exhibited strong immunoregulatory properties that were able to reduce surgery-induced elevations in cerebrovascular integrity impairment, subsequent peripheral immune-cell recruitment, and inflammation amplification, which ultimately lead to cognitive decline. The nt-p65-TMD has the unique ability to regulate and reduce systemic inflammation and inflammation amplification, suggesting a new strategy for preventing development of cognitive decline that occurs in POCD.

Optimization of IL13Rα2-Targeted Chimeric Antigen Receptor T Cells for Improved Anti-tumor Efficacy against Glioblastoma

T cell immunotherapy is emerging as a powerful strategy to treat cancer and may improve outcomes for patients with glioblastoma (GBM). We have developed a chimeric antigen receptor (CAR) T cell immunotherapy targeting IL-13 receptor α2 (IL13Rα2) for the treatment of GBM. Here, we describe the optimization of IL13Rα2-targeted CAR T cells, including the design of a 4-1BB (CD137) co-stimulatory CAR (IL13BBζ) and a manufacturing platform using enriched central memory T cells. Utilizing orthotopic human GBM models with patient-derived tumor sphere lines in NSG mice, we found that IL13BBζ-CAR T cells improved anti-tumor activity and T cell persistence as compared to first-generation IL13ζ-CAR CD8⁺ T cells that had shown evidence for bioactivity in patients. Investigating the impact of corticosteroids, given their frequent use in the clinical management of GBM, we demonstrate that low-dose dexamethasone does not diminish CAR T cell anti-tumor activity in vivo. Furthermore, we found that local intracranial delivery of CAR T cells elicits superior anti-tumor efficacy as compared to intravenous administration, with intraventricular infusions exhibiting possible benefit over intracranial tumor infusions in a multifocal disease model. Overall, these findings help define parameters for the clinical translation of CAR T cell therapy for the treatment of brain tumors.

Plasma and cerebrospinal fluid interleukin-1β during lipopolysaccharide-induced systemic inflammation in ewes implanted or not with slow-release melatonin

Background

Interleukin-1β (IL-1β) is important mediator of inflammatory-induced suppression of reproductive axis at the hypothalamic level. At the beginning of inflammation, the main source of cytokines in the cerebrospinal fluid (CSF) is peripheral circulation, while over time, cytokines produced in the brain are more important. Melatonin has been shown to decrease pro-inflammatory cytokines concentration in the brain. In ewes, melatonin is used to advance the onset of a breading season. Little is known about CSF concentration of IL-1β in ewes and its correlation with plasma during inflammation as well as melatonin action on the concentration of IL-1β in blood plasma and the CSF, and brain barriers permeability in early stage of lipopolysaccharide (LPS)-induced inflammation.

Methods

Systemic inflammation was induced through LPS administration in melatonin- and sham-implanted ewes. Blood and CSF samples were collected before and after LPS administration and IL-1β and albumin concentration were measured. To assess the functions of brain barriers albumin quotient (QAlb) was used. Expression of IL-1β (Il1B) and its receptor type I (Il1r1) and type II (Il1r2) and matrix metalloproteinase (Mmp) 3 and 9 was evaluated in the choroid plexus (CP).

Results

Before LPS administration, IL-1β was on the level of 62.0 ± 29.7 pg/mL and 66.4 ± 32.1 pg/mL in plasma and 26.2 ± 5.4 pg/mL and 21.3 ± 8.7 pg/mL in the CSF in sham- and melatonin-implanted group, respectively. Following LPS it increased to 159.3 ± 53.1 pg/mL and 197.8 ± 42.8 pg/mL in plasma and 129.8 ± 54.2 pg/mL and 139.6 ± 51.5 pg/mL in the CSF. No correlations was found between plasma and CSF IL-1β concentration after LPS in both groups. The QAlb calculated before LPS and 6 h after was similar in all groups. Melatonin did not affected mRNA expression of Il1B, Il1r1 and Il1r2 in the CP. The mRNA expression of Mmp3 and Mmp9 was not detected.

Conclusions

The lack of correlation between plasma and CSF IL-1β concentration indicates that at the beginning of inflammation the local synthesis of IL-1β in the CP is an important source of IL-1β in the CSF. Melatonin from slow-release implants does not affect IL-1β concentration in plasma and CSF in early stage of systemic inflammation.

Childhood maltreatment severity is associated with elevated C-reactive protein and body mass index in adults with schizophrenia and bipolar diagnoses

BACKGROUND

Several studies have described an association between childhood maltreatment and inflammatory markers in the psychotic disorders (schizophrenia [SZ] and bipolar disorder [BD]). Previous studies have been relatively small (<50 participants), and the severity of abuse and the putative influence of body mass index (BMI) have not been properly investigated.

METHODS

The combined effects of childhood abuse severity and clinical diagnosis on inflammatory markers were investigated in a large sample (n=483) of patients with a disorder on the psychosis spectrum and in healthy controls (HCs). Plasma levels of inflammatory markers (high-sensitivity C-reactive protein [hs-CRP], soluble tumor necrosis factor receptor type 1 [TNFR-R1], glycoprotein 130 [gp130]) were analyzed, and BMI and data on childhood trauma events, on the basis of the Childhood Trauma Questionnaire (CTQ), were obtained from all participants.

RESULTS

Patients had increased levels of hs-CRP (P<0.001, Cohens d=0.4), lower levels of gp130 (P<0.001, Cohens d=0.5), higher BMI (P<0.001, Cohens d=0.5) and reported more childhood maltreatment experiences (P<0.001, Cohens d=1.2) than the HC group. The severity of childhood abuse (up to three types of abuse: sexual abuse, physical abuse, and emotional abuse) was associated with elevated BMI (f=8.46, P<0.001, Cohen's d=0.5) and hs-CRP (f=5.47, P=0.001, Cohen's d=0.3). Combined effects of patient status and severity of childhood abuse were found for elevated hs-CRP (f=4.76, P<0.001, Cohen's d=0.4). Differences among the groups disappeared when BMI was added to the model.

DISCUSSION

Trauma-altered immune activation via elevated hs-CRP in patients with SZ and BD may be mediated by higher BMI; however, the direction of this association needs further clarification.

Immunoregulatory effect of mast cells influenced by microbes in neurodegenerative diseases

When related to central nervous system (CNS) health and disease, brain mast cells (MCs) can be a source of either beneficial or deleterious signals acting on neural cells. We review the current state of knowledge about molecular interactions between MCs and glia in neurodegenerative diseases such as Multiple Sclerosis, Alzheimer's disease, Amyotrophic Lateral Sclerosis, Parkinson's disease, Epilepsy. We also discuss the influence on MC actions evoked by the host microbiota, which has a profound effect on the host immune system, inducing important consequences in neurodegenerative disorders. Gut dysbiosis, reduced intestinal motility and increased intestinal permeability, that allow bacterial products to circulate and pass through the blood-brain barrier, are associated with neurodegenerative disease. There are differences between the microbiota of neurologic patients and healthy controls. Distinguishing between cause and effect is a challenging task, and the molecular mechanisms whereby remote gut microbiota can alter the brain have not been fully elucidated. Nevertheless, modulation of the microbiota and MC activation have been shown to promote neuroprotection. We review this new information contributing to a greater understanding of MC-microbiota-neural cells interactions modulating the brain, behavior and neurodegenerative processes.

Regulation of Microglia and Macrophage Polarization via Apoptosis Signal-Regulating Kinase 1 Silencing after Ischemic/Hypoxic Injury

Inflammation is implicated in ischemic stroke and is involved in abnormal homeostasis. Activation of the immune system leads to breakdown of the blood-brain barrier and, thereby, infiltration of immune cells into the brain. Upon cerebral ischemia, infiltrated macrophages and microglia (resident CNS immune cell) are activated, change their phenotype to M1 or M2 based on the microenvironment, migrate toward damaged tissue, and are involved in repair or damage. Those of M1 phenotype release pro-inflammatory mediators, which are associated with tissue damage, while those of M2 phenotype release anti-inflammatory mediators, which are related to tissue recovery. Moreover, late inflammation continually stimulates immune cell infiltration and leads to brain infarction. Therefore, regulation of M1/M2 phenotypes under persistent inflammatory conditions after cerebral ischemia is important for brain repair. Herein, we focus on apoptosis signal-regulating kinase 1 (ASK1), which is involved in apoptotic cell death, brain infarction, and production of inflammatory mediators after cerebral ischemia. We hypothesized that ASK1 is involved in the polarization of M1/M2 phenotype and the function of microglia and macrophage during the late stage of ischemia/hypoxia. We investigated the effects of ASK1 in mice subjected to middle cerebral artery occlusion and on BV2 microglia and RAW264.7 macrophage cell lines subjected to oxygen-glucose deprivation. Our results showed that ASK1 silencing effectively reduced Iba-1 or CD11b-positive cells in ischemic areas, suppressed pro-inflammatory cytokines, and increased anti-inflammatory mediator levels at 7 days after cerebral ischemia. In cultured microglia and macrophages, ASK1 inhibition, induced by NQDI-1 drug, decreased the expression and release of M1-associated factors and increased those of M2-associated factors after hypoxia/reperfusion (H/R). At the gene level, ASK1 inhibition suppressed M1-associated genes and augmented M2-associated genes. In gap closure assay, ASK1 inhibition reduced the migration rate of microglia and macrophages after H/R. Taken together, our results provide new information that suggests ASK1 controls the polarization of M1/M2 and the function of microglia and macrophage under sustained-inflammatory conditions. Regulation of persistent inflammation via M1/M2 polarization by ASK1 is a novel strategy for repair after ischemic stroke.

Attention deficit hyperactivity disorder may be a highly inflammation and immune-associated disease (Review)

Attention deficit hyperactivity disorder (ADHD) is a common behavioral disorder. Previous research has indicated that genetic factors, family education, environment and dietary habits are associated with ADHD. It has been determined that in China many children with ADHD also have allergic rhinitis or asthma. These children are more susceptible to the common cold or upper respiratory infections compared with normal healthy children. Additionally, the common cold or an upper respiratory infection may lead to disease recurrence or worsen the symptoms in these children. Previous studies have determined that ADHD may have a close association with allergic disease. Based on the clinically observed phenomenon and previous studies, it was hypothesized that ADHD is a high inflammation and immune‑associated disease. Therefore, the authors designed clinical and animal experiments to test this hypothesis in the future. Immune system disorders may be a novel part of the etiology of ADHD. The current report may have implications for future clinical practice.

Co-infection with HIV associated with reduced vulnerability to symptoms of depression during antiviral treatment for hepatitis C

In this prospective study, we examined new-onset major depressive disorder (MDD) and the differential expression of depressive symptoms in a sample of 132 HCV mono-infected and 40 HIV/HCV co-infected patients initiating pegylated interferon-based treatment, including protease inhibitor therapy. The semi-structured clinical interview (SCID-I) was used to assess MDD. Severity of depressive symptoms was assessed using the Hamilton Depression Rating Scale. Of the total sample, 60 patients (34.9%) developed SCID-I defined MDD during antiviral treatment. The proportion of HCV mono- and HIV/HCV patients developing MDD during treatment was not significantly different (37.9% vs. 25%; p=0.185). In both groups, there was a significant increase in HAMD total score from baseline to week 4, and a significant decrease between week 24 and 6 months post-treatment cessation. The greatest increase was observed in the symptoms of the neurovegetative syndrome. HCV mono-infected patients reported higher scores than co-infected patients, particularly impaired activity and somatic symptoms, but the differences were only significant at week 12. The finding that co-infected patients appear less vulnerable to the development of depressive symptoms during HCV treatment than HCV mono-infected patients warrants further exploration, including a thorough analysis of the biological and psychosocial factors associated with this emergence.

The increased concentration of macrophage migration inhibitory factor in serum and cerebrospinal fluid of patients with tick-borne encephalitis

Background

Host factors determining the clinical presentation of tick-borne encephalitis (TBE) are not fully elucidated. The peripheral inflammatory response to TBE virus is hypothesized to facilitate its entry into central nervous system by disrupting the blood-brain barrier with the involvement of a signaling route including Toll-like receptor 3 (TLR3) and pro-inflammatory cytokines macrophage migration inhibitory factor (MIF), tumor necrosis factor-α (TNFα), and interleukin-1 beta (IL-1β).

Methods

Concentrations of MIF, TNFα, and IL-1β were measured with commercial ELISA in serum and cerebrospinal fluid (CSF) from 36 hospitalized TBE patients, 7 patients with non-TBE meningitis, and 6 controls. The CSF albumin quotient (AQ) was used as a marker of blood-brain barrier permeability. Single nucleotide polymorphisms rs3775291, rs5743305 (associated with TLR3 expression), and rs755622 (associated with MIF expression) were assessed in blood samples from 108 TBE patients and 72 non-TBE controls. The data were analyzed with non-parametric tests, and p < 0.05 was considered significant.

Results

The median serum and CSF concentrations of MIF and IL-1β were significantly increased in TBE group compared to controls. MIF concentration in serum tended to correlate with AQ in TBE, but not in non-TBE meningitis. The serum concentration of TNFα was increased in TBE patients bearing a high-expression TLR3 rs5743305 TT genotype, which also associated with the increased risk of TBE. The low-expression rs3775291 TLR3 genotype TT associated with a prolonged increase of CSF protein concentration. The high-expression MIF rs755622 genotype CC tended to correlate with an increased risk of TBE, and within TBE group, it was associated with a mild presentation.

Conclusions

The results point to the signaling route involving TLR3, MIF, and TNFα being active in TBE virus infection and contributing to the risk of an overt neuroinvasive disease. The same factors may play a protective role intrathecally contributing to the milder course of neuroinfection. This suggests that the individual variability of the risk and clinical presentation of TBE might be traced to the variable peripheral and intrathecal expression of the mediators of the inflammatory response, which in turn associates with the host genetic background.

Sepsis-Associated Encephalopathy: The Blood-Brain Barrier and the Sphingolipid Rheostat

Sepsis is not only a significant cause of mortality worldwide but has particularly devastating effects on the central nervous system of survivors. It is therefore crucial to understand the molecular structure, physiology, and events involved in the pathogenesis of sepsis-associated encephalopathy, so that potential therapeutic advances can be achieved. A key determinant to the development of this type of encephalopathy is morphological and functional modification of the blood–brain barrier (BBB), whose function is to protect the CNS from pathogens and toxic threats. Key mediators of pathologic sequelae of sepsis in the brain include cytokines, including TNF-α, and sphingolipids, which are biologically active components of cellular membranes that possess diverse functions. Emerging data demonstrated an essential role for sphingolipids in the pulmonary vascular endothelium. This raises the question of whether endothelial stability in other organs systems such as the CNS may also be mediated by sphingolipids and their receptors. In this review, we will model the structure and vulnerability of the BBB and hypothesize mechanisms for therapeutic stabilization and repair following a confrontation with sepsis-induced inflammation.

Are the Gut Bacteria Telling Us to Eat or Not to Eat? Reviewing the Role of Gut Microbiota in the Etiology, Disease Progression and Treatment of Eating Disorders

Traditionally recognized as mental illnesses, eating disorders are increasingly appreciated to be biologically-driven. There is a growing body of literature that implicates a role of the gut microbiota in the etiology and progression of these conditions. Gut bacteria may act on the gut–brain axis to alter appetite control and brain function as part of the genesis of eating disorders. As the illnesses progress, extreme feeding patterns and psychological stress potentially feed back to the gut ecosystem that can further compromise physiological, cognitive, and social functioning. Given the established causality between dysbiosis and metabolic diseases, an altered gut microbial profile is likely to play a role in the co-morbidities of eating disorders with altered immune function, short-chain fatty acid production, and the gut barrier being the key mechanistic links. Understanding the role of the gut ecosystem in the pathophysiology of eating disorders will provide critical insights into improving current treatments and developing novel microbiome-based interventions that will benefit patients with eating disorders.

CECOG educational illustrations: the blood-brain barrier and its relevance for targeted cancer therapies and immuno-oncology

Click here to view the Educational slides.

The blood–brain barrier (BBB) protects the central nervous system (CNS) from potentially harmful substances and molecules by limiting their influx from the blood stream into the brain parenchyma. Understanding the structure and functioning of the BBB is of major importance for the development of effective medical treatments for primary and secondary brain tumours. Therefore, we provide here a concise and illustrated educational description of the anatomy and physiology of the BBB and current concepts on its role for targeted cancer therapies and immuno-oncology.

An immunocompetent mouse model of human glioblastoma

Orthotopic xenotransplantation studies represent the final stage in preclinical cancer research and could facilitate the implementation of precision medicine. To date, these xenografts have been tested in immunodeficient animals, but complete elimination of the adaptive immunity is a significant drawback. We present a method of efficient human glioblastoma (GBM) cell engraftment in adult mice with intact immune systems, mediated by a transient blockade of T-cell co-stimulation. Compared to transplants grown in immunodeficient hosts, the resulting tumors more accurately resemble the clinical pathophysiology of patient GBMs, which are characterized by blood-brain-barrier leakage and strong neo-vascularization. We expect our method to have great utility for studying human tumor cell biology, particularly in the field of cancer immunotherapy and in studies on microenvironmental interactions. Given the straightforward approach, the method may also be applicable to other tumor types and additional model organisms.

Toll-like receptor signaling and stages of addiction

BACKGROUND

Athina Markou and her colleagues discovered persistent changes in adult behavior following adolescent exposure to ethanol or nicotine consistent with increased risk for developing addiction. Building on Dr. Markou's important work and that of others in the field, researchers at the Bowles Center for Alcohol Studies have found that persistent changes in behavior following adolescent stress or alcohol exposure may be linked to induction of immune signaling in brain.

AIM

This study aims to illuminate the critical interrelationship of the innate immune system (e.g., toll-like receptors [TLRs], high-mobility group box 1 [HMGB1]) in the neurobiology of addiction.

METHOD

This study reviews the relevant research regarding the relationship between the innate immune system and addiction.

CONCLUSION

Emerging evidence indicates that TLRs in brain, particularly those on microglia, respond to endogenous innate immune agonists such as HMGB1 and microRNAs (miRNAs). Multiple TLRs, HMGB1, and miRNAs are induced in the brain by stress, alcohol, and other drugs of abuse and are increased in the postmortem human alcoholic brain. Enhanced TLR-innate immune signaling in brain leads to epigenetic modifications, alterations in synaptic plasticity, and loss of neuronal cell populations, which contribute to cognitive and emotive dysfunctions. Addiction involves progressive stages of drug binges and intoxication, withdrawal-negative affect, and ultimately compulsive drug use and abuse. Toll-like receptor signaling within cortical-limbic circuits is modified by alcohol and stress in a manner consistent with promoting progression through the stages of addiction.

Memory and multitasking performance during acute allergic inflammation in seasonal allergic rhinitis

BACKGROUND

In previous research, patients with seasonal allergic rhinitis (SAR) showed poorer school and work performance during periods of acute allergic inflammation, supporting the idea of an impact of SAR on cognitive functions. However, the specific cognitive domains particularly vulnerable to inflammatory processes are unclear.

OBJECTIVE

In this study, the influence of SAR on memory and multitasking performance, as two potentially vulnerable cognitive domains essential in everyday life functioning, was investigated in patients with SAR.

METHODS

Non-medicated patients with SAR (n = 41) and healthy non-allergic controls (n = 42) performed a dual-task paradigm and a verbal learning and memory test during and out of symptomatic allergy periods (pollen vs. non-pollen season). Disease-related factors (e.g. symptom severity, duration of symptoms, duration of disease) and allergy-related quality of life were evaluated as potential influences of cognitive performance.

RESULTS

During the symptomatic allergy period, patients showed (1) poorer performance in word list-based learning (P = 0.028) and (2) a general slowing in processing speed (P < 0.001) and a shift in processing strategy (P < 0.001) in multitasking. Yet, typical parameters indicating specific multitasking costs were not affected. A significant negative association was found between learning performance and duration of disease (r = -0.451, P = 0.004), whereas symptom severity (r = 0.326; P = 0.037) and quality of life (r = 0.379; P = 0.015) were positively associated with multitasking strategy.

CONCLUSIONS

Our findings suggest that SAR has a differentiated and complex impact on cognitive functions, which should be considered in the management of SAR symptoms. They also call attention to the importance of selecting sensitive measures and carefully interpreting cognitive outcomes.

Activation of melatonin receptor (MT1/2) promotes P-gp transporter in methamphetamine-induced toxicity on primary rat brain microvascular endothelial cells

Melatonin has been known as a neuroprotective agent for the central nervous system (CNS) and the blood-brain barrier (BBB), which is the primary structure that comes into contact with several neurotoxins including methamphetamine (METH). Previous studies have reported that the activation of melatonin receptors (MT1/2) by melatonin could protect against METH-induced toxicity in brain endothelial cells via several mechanisms. However, its effects on the P-glycoprotein (P-gp) transporter, the active efflux pump involved in cell homeostasis, are still unclear. Thus, this study investigated the role of melatonin and its receptors on the METH-impaired P-gp transporter in primary rat brain microvascular endothelial cells (BMVECs). The results showed that METH impaired the function of the P-gp transporter, significantly decreasing the efflux of Rho123 and P-gp expression, which caused a significant increase in the intracellular accumulation of Rho123, and these responses were reversed by the interaction of melatonin with its receptors. Blockade of the P-gp transporter by verapamil caused oxidative stress, apoptosis, and cell integrity impairment after METH treatment, and these effects could be reversed by melatonin. Our results, together with previous findings, suggest that the interaction of melatonin with its receptors protects against the effects of the METH-impaired P-gp transporter and that the protective role in METH-induced toxicity was at least partially mediated by the regulation of the P-gp transporter. Thus, melatonin and its receptors (MT1/2) are essential for protecting against BBB impairment caused by METH.

'Multimorbidity' as the manifestation of network disturbances

We argue that 'multimorbidity' is the manifestation of interconnected physiological network processes within an individual in his or her socio-cultural environment. Networks include genomic, metabolomic, proteomic, neuroendocrine, immune and mitochondrial bioenergetic elements, as well as social, environmental and health care networks. Stress systems and other physiological mechanisms create feedback loops that integrate and regulate internal networks within the individual. Minor (e.g. daily hassles) and major (e.g. trauma) stressful life experiences perturb internal and social networks resulting in physiological instability with changes ranging from improved resilience to unhealthy adaptation and 'clinical disease'. Understanding 'multimorbidity' as a complex adaptive systems response to biobehavioural and socio-environmental networks is essential. Thus, designing integrative care delivery approaches that more adequately address the underlying disease processes as the manifestation of a state of physiological dysregulation is essential. This framework can shape care delivery approaches to meet the individual's care needs in the context of his or her underlying illness experience. It recognizes 'multimorbidity' and its symptoms as the end product of complex physiological processes, namely, stress activation and mitochondrial energetics, and suggests new opportunities for treatment and prevention. The future of 'multimorbidity' management might become much more discerning by combining the balancing of physiological dysregulation with targeted personalized biotechnology interventions such as small molecule therapeutics targeting specific cellular components of the stress response, with community-embedded interventions that involve addressing psycho-socio-cultural impediments that would aim to strengthen personal/social resilience and enhance social capital.

Inflammation Effects on Motivation and Motor Activity: Role of Dopamine

Motivational and motor deficits are common in patients with depression and other psychiatric disorders, and are related to symptoms of anhedonia and motor retardation. These deficits in motivation and motor function are associated with alterations in corticostriatal neurocircuitry, which may reflect abnormalities in mesolimbic and mesostriatal dopamine (DA). One pathophysiologic pathway that may drive changes in DAergic corticostriatal circuitry is inflammation. Biomarkers of inflammation such as inflammatory cytokines and acute-phase proteins are reliably elevated in a significant proportion of psychiatric patients. A variety of inflammatory stimuli have been found to preferentially target basal ganglia function to lead to impaired motivation and motor activity. Findings have included inflammation-associated reductions in ventral striatal neural responses to reward anticipation, decreased DA and DA metabolites in cerebrospinal fluid, and decreased availability, and release of striatal DA, all of which correlated with symptoms of reduced motivation and/or motor retardation. Importantly, inflammation-associated symptoms are often difficult to treat, and evidence suggests that inflammation may decrease DA synthesis and availability, thus circumventing the efficacy of standard pharmacotherapies. This review will highlight the impact of administration of inflammatory stimuli on the brain in relation to motivation and motor function. Recent data demonstrating similar relationships between increased inflammation and altered DAergic corticostriatal circuitry and behavior in patients with major depressive disorder will also be presented. Finally, we will discuss the mechanisms by which inflammation affects DA neurotransmission and relevance to novel therapeutic strategies to treat reduced motivation and motor symptoms in patients with high inflammation.

Astrocyte-derived interleukin-15 exacerbates ischemic brain injury via propagation of cellular immunity

Astrocytes are believed to bridge interactions between infiltrating lymphocytes and neurons during brain ischemia, but the mechanisms for this action are poorly understood. Here we found that interleukin-15 (IL-15) is dramatically up-regulated in astrocytes of postmortem brain tissues from patients with ischemic stroke and in a mouse model of transient focal brain ischemia. We generated a glial fibrillary acidic protein (GFAP) promoter-controlled IL-15-expressing transgenic mouse (GFAP-IL-15^tg) line and found enlarged brain infarcts, exacerbated neurodeficits after the induction of brain ischemia. In addition, knockdown of IL-15 in astrocytes attenuated ischemic brain injury. Interestingly, the accumulation of CD8⁺ T and natural killer (NK) cells was augmented in these GFAP-IL-15^tg mice after brain ischemia. Of note, depletion of CD8⁺ T or NK cells attenuated ischemic brain injury in GFAP-IL-15^tg mice. Furthermore, knockdown of the IL-15 receptor α or blockade of cell-to-cell contact diminished the activation and effector function of CD8⁺ T and NK cells in GFAP-IL-15^tg mice, suggesting that astrocytic IL-15 is delivered in trans to target cells. Collectively, these findings indicate that astrocytic IL-15 could aggravate postischemic brain damage via propagation of CD8⁺ T and NK cell-mediated immunity.

Balancing the immune response in the brain: IL-10 and its regulation

Background

The inflammatory response is critical to fight insults, such as pathogen invasion or tissue damage, but if not resolved often becomes detrimental to the host. A growing body of evidence places non-resolved inflammation at the core of various pathologies, from cancer to neurodegenerative diseases. It is therefore not surprising that the immune system has evolved several regulatory mechanisms to achieve maximum protection in the absence of pathology.

Main body

The production of the anti-inflammatory cytokine interleukin (IL)-10 is one of the most important mechanisms evolved by many immune cells to counteract damage driven by excessive inflammation. Innate immune cells of the central nervous system, notably microglia, are no exception and produce IL-10 downstream of pattern recognition receptors activation. However, whereas the molecular mechanisms regulating IL-10 expression by innate and acquired immune cells of the periphery have been extensively addressed, our knowledge on the modulation of IL-10 expression by central nervous cells is much scattered. This review addresses the current understanding on the molecular mechanisms regulating IL-10 expression by innate immune cells of the brain and the implications of IL-10 modulation in neurodegenerative disorders.

Conclusion

The regulation of IL-10 production by central nervous cells remains a challenging field. Answering the many remaining outstanding questions will contribute to the design of targeted approaches aiming at controlling deleterious inflammation in the brain.