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Intracerebral vector delivery in nonhuman primates has been a major challenge. We report successful blood-brain barrier opening and focal delivery of adeno-associated virus serotype 9 vectors into brain regions involved in Parkinson’s disease using low-intensity focus ultrasound in adult macaque monkeys. Openings were well tolerated with generally no associated abnormal magnetic resonance imaging signals. Neuronal green fluorescent protein expression was observed specifically in regions with confirmed blood-brain barrier opening. Similar blood-brain barrier openings were safely demonstrated in three patients with Parkinson’s disease. In these patients and in one monkey, blood-brain barrier opening was followed by 18F-Choline uptake in the putamen and midbrain regions based on positron emission tomography. This indicates focal and cellular binding of molecules that otherwise would not enter the brain parenchyma. The less-invasive nature of this methodology could facilitate focal viral vector delivery for gene therapy and might allow early and repeated interventions to treat neurodegenerative disorders., 血液脳関門開放術による遺伝子治療法の開発 --身体を傷つけない脳疾患の治療を目指して--. 京都大学プレスリリース. 2023-04-20.

A key pathological event occurring in Parkinson's disease (PD) is the transneuronal spreading of alpha-synuclein (α-syn). Other hallmarks of PD include neurodegeneration, glial activation, and immune cell infiltration in susceptible brain regions. Although preclinical models can mimic most of the key characteristics of PD, it is crucial to know the biological bases of individual differences between them when choosing one over another, to ensure proper interpretation of the results and to positively influence the outcome of the experiments.This review provides an overview of current preclinical models actively used to study the interplay between α-syn pathology, neuroinflammation and immune response in PD but also to explore new potential preclinical models or emerging therapeutic strategies intended to fulfill the unmet medical needs in this disease. Lastly, this review also considers the current state of the ongoing clinical trials of new drugs designed to target these processes and delay the initiation or progression of the disease.Anti-inflammatory and immunomodulatory agents have been demonstrated to be very promising candidates for reducing disease progression; however, more efforts are needed to reduce the enormous gap between these and dopaminergic drugs, which have dominated the therapeutic market for the last sixty years.

Since December 2019, the world has been shaken by the spread of a highly pathogen virus, causing severe acute respiratory syndrome (SARS-Cov2), which emerged in Wuhan, China. SARS-Cov2 is known to cause acute pneumonia: the cardinal feature of coronavirus disease 2019 (COVID-19). Clinical features of the disease include respiratory distress, loss of spontaneous breathing, and sometimes neurologic signs such as headache and nausea and anosmia, leading to suppose a possible involvement of the nervous system as a potential target of SARS-CoV2. The chapter will shed light on the recent clinical and experimental data sustaining the involvement of the nervous system in the pathophysiology of COVID-19, based on several case reports and experimental data reporting the possible transmission of SARS-CoV2 throughout the peripheral nerves to the brain cardiorespiratory centers. Thus, understanding the role of the nervous system in the course of clinical symptoms of COVID-19 is important in determining the appropriate therapeutic approach to combat the disease.

Severe acute respiratory syndrome coronavirus 2 (SARS-CoV-2) preferentially infects cells in the respiratory tract, but several studies have also demonstrated low levels of SARS-CoV-2 copies in the liver. The hypothesis that patients with COVID-19 may develop liver dysfunction is supported by findings showing abnormal liver test results in such patients, but the exact mechanisms by which SARS-CoV-2 induces liver damage remain unclear. Liver injury in COVID-19 patients has probably a multifactorial etiology including the rapid onset of a systemic pro-inflammatory state due to viral infection, the use of potentially hepatotoxic drugs, pneumonia-associated hypoxia, and the eventual direct injury of the liver by SARS-CoV-2. This chapter will discuss the potential pathophysiological mechanisms for SARS-CoV-2 hepatic tropism and an overview about the main biochemical and histopathological findings observed in liver from COVID-19 patients. Finally, the effects that this infection can produce in patients with chronic liver disease will be also discussed.

Aims Chronic hyperammonaemia and inflammation synergistically induce neurological impairment, including motor incoordination, in hepatic encephalopathy. Hyperammonaemic rats show neuroinflammation in the cerebellum which enhances GABAergic neurotransmission leading to motor incoordination. We aimed to identify underlying mechanisms. The aims were (1) to assess if S1PR2 is involved in microglial and astrocytic activation in the cerebellum of hyperammonaemic rats; (2) to identify pathways by which enhanced S1PR2 activation induces neuroinflammation and alters neurotransmission; (3) to assess if blocking S1PR2 reduces neuroinflammation and restores motor coordination in hyperammonaemic rats. Methods We performed ex vivo studies in cerebellar slices from control or hyperammonaemic rats to identify pathways by which neuroinflammation enhances GABAergic neurotransmission in hyperammonaemia. Neuroinflammation and neurotransmission were assessed by immunochemistry/immunofluorescence and western blot. S1PR2 was blocked by intracerebral treatment with JTE-013 using osmotic mini-pumps. Motor coordination was assessed by beam walking. Results Chronic hyperammonaemia enhances S1PR2 activation in the cerebellum by increasing its membrane expression. This increases CCL2, especially in Purkinje neurons. CCL2 activates CCR2 in microglia, leading to microglial activation, increased P2X4 membrane expression and BDNF in microglia. BDNF enhances TrkB activation in neurons, increasing KCC2 membrane expression. This enhances GABAergic neurotransmission, leading to motor incoordination in hyperammonaemic rats. Blocking S1PR2 in hyperammonaemic rats by intracerebral administration of JTE-013 normalises the S1PR2-CCL2-CCR2-BDNF-TrkB-KCC2 pathway, reduces glial activation and restores motor coordination in hyperammonaemic rats. Conclusions Enhanced S1PR2-CCL2-BDNF-TrkB pathway activation mediates neuroinflammation and incoordination in hyperammonaemia. The data raise a promising therapy for patients with hepatic encephalopathy using compounds targeting this pathway.

In patients with liver cirrhosis, minimal hepatic encephalopathy (MHE) is triggered by a shift in peripheral inflammation, promoting lymphocyte infiltration into the brain. Rifaximin improves neurological function in MHE by normalizing peripheral inflammation. Patients who died with steatohepatitis showed T-lymphocyte infiltration and neuroinflammation in the cerebellum, suggesting that MHE may already occur in these patients. The aims of this work were to assess, in a rat model of mild liver damage similar to steatohepatitis, whether: (1) the rats show impaired motor coordination in the early phases of liver damage, (2) this is associated with changes in the immune system and infiltration of immune cells into the brain, and (3) rifaximin improves motor incoordination, associated with improved peripheral inflammation, reduced infiltration of immune cells and neuroinflammation in the cerebellum, and restoration of the alterations in neurotransmission. Liver damage was induced by carbon tetrachloride (CCl4) injection over four weeks. Peripheral inflammation, immune cell infiltration, neuroinflammation, and neurotransmission in the cerebellum and motor coordination were assessed. Mild liver damage induces neuroinflammation and altered neurotransmission in the cerebellum and motor incoordination. These alterations are associated with increased TNFa, CCL20, and CX3CL1 in plasma and cerebellum, IL-17 and IL-15 in plasma, and CCL2 in cerebellum. This promotes T-lymphocyte and macrophage infiltration in the cerebellum. Early treatment with rifaximin prevents the shift in peripheral inflammation, immune cell infiltration, neuroinflammation, and motor incoordination. This report provides new clues regarding the mechanisms of the beneficial effects of rifaximin, suggesting that early rifaximin treatment could prevent neurological impairment in patients with steatohepatitis.

Cognitive and motor impairment in minimal hepatic encephalopathy (MHE) are mediated by neuroinflammation, which is induced by hyperammonemia and peripheral inflammation. GABAergic neurotransmission in the cerebellum is altered in rats with chronic hyperammonemia. The mechanisms by which hyperammonemia induces neuroinflammation remain unknown. We hypothesized that GABAA receptors can modulate cerebellar neuroinflammation. The GABAA antagonist bicuculline was administrated daily (i.p.) for four weeks in control and hyperammonemic rats. Its effects on peripheral inflammation and on neuroinflammation as well as glutamate and GABA neurotransmission in the cerebellum were assessed. In hyperammonemic rats, bicuculline decreases IL-6 and TNFα and increases IL-10 in the plasma, reduces astrocyte activation, induces the microglia M2 phenotype, and reduces IL-1β and TNFα in the cerebellum. However, in control rats, bicuculline increases IL-6 and decreases IL-10 plasma levels and induces microglial activation. Bicuculline restores the membrane expression of some glutamate and GABA transporters restoring the extracellular levels of GABA in hyperammonemic rats. Blocking GABAA receptors improves peripheral inflammation and cerebellar neuroinflammation, restoring neurotransmission in hyperammonemic rats, whereas it induces inflammation and neuroinflammation in controls. This suggests a complex interaction between GABAergic and immune systems. The modulation of GABAA receptors could be a suitable target for improving neuroinflammation in MHE.

Food addiction (FA) is characterized by behavioral and neurochemical changes linked to loss of food intake control. Gut microbiota may influence appetite and food intake via endocrine and neural routes. The gut microbiota is known to impact homeostatic energy mechanisms, but its role in regulating the reward system is less certain. We show that the administration of Bacteroides uniformis CECT 7771 (B. uniformis) in a rat FA model impacts on the brain reward response, ameliorating binge eating and decreasing anxiety-like behavior. These effects are mediated, at least in part, by changes in the levels of dopamine, serotonin, and noradrenaline in the nucleus accumbens and in the expression of dopamine D1 and D2 receptors in the prefrontal cortex and intestine. B. uniformis reverses the fasting-induced microbiota changes and increases the abundance of species linked to healthy metabolotypes. Our data indicate that microbiota-based interventions might help to control compulsive overeating by modulating the reward response., Open Access funding provided thanks to the CRUE-CSIC agreement with Springer Nature. This work was supported by grants AGL2014-52101-P and AGL2017-88801-P from the Ministry of Science, Innovation and Universities (MCIU, Spain) and by grant PROMETEO/2019/015 from “Conselleria de Educación, Investigación, Cultura y Deporte” (Generalitat Valenciana, Spain). The contracts of ABP are also supported by grant AGL2017-88801-P. The pre-doctoral contract (FPI) of ILA and the technician contract (PTA) of IC from MCIU (Spain) are also fully acknowledged.

Substantial epidemiological studies have established a link between environmental factors and prevalence of neurodegenerative diseases. Increasingly, some studies report a direct cause-and-effect relation between environmental agents such as heavy metals and pesticides, and some neurodegenerative disorders including multiple sclerosis (MS) and Huntington's disease (HD). Interestingly, high blood level of heavy metals and pesticides has been shown in patients with MS and HD. Those agents could be involved directly or indirectly in the pathogenesis of MS and HD. The underlying mechanisms may imply an immune breaking of self-tolerance or neurodegeneration onset of several neurotransmission systems. The chapter will discuss the role of different metals and pesticides in the onset and progress of MS and HD with an overview of the possible underlying pathomechanisms.

Alcoholic steatohepatitis (ASH) and nonalcoholic steatohepatitis (NASH) affect 29 million people in the European Union. Patients with ASH and NASH may exhibit cognitive impairment, reducing their quality of life. Steatohepatitis induces cerebral alterations. It is not known if histological analysis could allow distinguishing ASH, NASH, and/or cirrhosis neuropathology and other entities. The aim of this work was to analyze a set of histopathological features characterizing the brain lesions due to ASH, NASH, and cirrhosis. We performed a histological study using hematoxylin and eosin staining and immunohistochemical techniques in cerebellum of 31 subjects who died with healthy liver (n = 6), NASH (n = 14), ASH (n = 3), nonalcoholic cirrhosis (n = 4), and alcoholic cirrhosis (n = 4). We analyzed in cerebellum, as an early marker for brain injury: 1) vascular damage; 2) cerebellar atrophy and neurodegeneration in Purkinje layer; and 3) microglia and astrocytes activation in white matter and molecular layer. Patients with steatohepatitis have increased number of microtrombi in cerebellar parenchyma, neuronal loss in Purkinje layer and microglial and astrocyte activation in white matter and molecular layer. These alterations are stronger in patients with ASH than in those with NASH. These results provide a set of histopathological features in brain that may allow differentiation of steatohepatitis from other conditions.

There is increasing evidence that extracellular cGMP modulates glutamatergic neurotransmission and some forms of learning. However, the underlying mechanisms remain unknown. We proposed the hypotheses that extracellular cGMP may regulate membrane expression of AMPA receptors. To do this extracellular cGMP should act on a membrane protein and activate signal transduction pathways modulating phosphorylation of the GluA1 and/or GluA2 subunits. It has been shown that extracellular cGMP modulates glycine receptors. The aims of this work were to assess: 1) whether extracellular cGMP modulates membrane expression of GluA1 and GluA2 subunits of AMPA receptors in cerebellum in vivo; 2) whether this is mediated by glycine receptors; 3) the role of GluA1 and GluA2 phosphorylation and 4) identify steps of the intracellular pathways involved. We show that extracellular cGMP modulates membrane expression of GluA1 and GluA2 in cerebellum in vivo and unveil the mechanisms involved. Extracellular cGMP reduced glycine receptor activation, modulating cAMP, protein kinases and phosphatases, and GluA1 and GluA2 phosphorylation, resulting in increased GluA1 and reduced GluA2 membrane expression. Extracellular cGMP therefore modulates membrane expression of AMPA receptors and glutamatergic neurotransmission. The steps identified may be therapeutic targets to improve neurotransmission and neurological function in pathological situations with abnormal glutamatergic neurotransmission.

Activated microglia and increased brain IL-1β play a main role in cognitive impairment in much pathology. We studied the role of IL-1β in neuroinflammation-induced impairment of the following different types of learning and memory: novel object recognition (NOR), novel object location (NOL), spatial learning, reference memory (RM), and working memory (WM). All these processes are impaired in hyperammonemic rats. We assessed which of these types of learning and memory are restored by blocking the IL-1 receptor in vivo in hyperammonemic rats and the possible mechanisms involved. Blocking the IL-1 receptor reversed microglial activation in the hippocampus, perirhinal cortex, and prefrontal cortex but not in the postrhinal cortex. This was associated with the restoration of NOR and WM but not of tasks involving a spatial component (NOL and RM). This suggests that IL-1β would be involved in neuroinflammation-induced nonspatial memory impairment, whereas spatial memory impairment would be IL-1β-independent and would be mediated by other proinflammatory factors.-Taoro-Gonzalez, L., Cabrera-Pastor, A., Sancho-Alonso, M., Arenas, Y. M., Meseguer-Estornell, F., Balzano, T., ElMlili, N., Felipo, V. Differential role of interleukin-1β in neuroinflammation-induced impairment of spatial and nonspatial memory in hyperammonemic rats.

Patients with hepatic encephalopathy (HE) show working memory and visuo-spatial orientation deficits. Hyperammonemia is a main contributor to cognitive impairment in HE. Hyperammonemic rats show impaired spatial learning and learning ability in the Y maze. Intracerebral administration of extracellular cGMP restores learning in the Y-maze. The underlying mechanisms remain unknown. It also remains unknown whether extracellular cGMP improves neuroinflammation or restores spatial learning in hyperammonemic rats and if it affects differently reference and working memory. The aims of this work were: Spatial working and reference memory were assessed using the radial and Morris water mazes and neuroinflammation by immunohistochemistry and Western blot. Membrane expression of NMDA and AMPA receptor subunits was analyzed using the BS3 crosslinker. Extracellular cGMP was administered intracerebrally using osmotic minipumps. Chronic hyperammonemia induces neuroinflammation in hippocampus, with astrocytes activation and increased IL-1β, which are associated with increased NMDA receptors membrane expression and impaired working memory. This process is not affected by extracellular cGMP. Hyperammonemia also activates microglia and increases TNF-α, alters membrane expression of AMPA receptor subunits (increased GluA1 and reduced GluA2) and impairs reference memory. All these changes are reversed by extracellular cGMP. These results show that extracellular cGMP modulates spatial reference memory but not working memory. This would be mediated by modulation of TNF-α levels and of membrane expression of GluA1 and GluA2 subunits of AMPA receptors.

The liver is the main detoxifier organ of the body. When normal liver function is compromised, other systems in the body can be affected, including the brain. Hepatocerebral disorder is the term used to describe some neuropsychiatric conditions that result from liver failure and characterized by the accumulation of these toxic metals in brain. Examples of such disorders are Wilson's disease (WD), an autosomal recessive disorder that is characterized by the deposition of copper in liver and brain tissues and acquired (non-Wilsonian) hepatocerebral degeneration (AHCD), a complication that occurs most frequently in patients with hepatic coma or that suffered multiple episodes of severe HE. AHCD is characterized by accumulation in brain of manganese. This chapter will focus on the crucial importance of relationship between liver and brain functioning and on the effects produced when this relationship is compromised. Specifically, the chapter will discuss on the physiopathology of WD and AHCD and on the role that toxic metals play on neurological symptoms in such disorders.

Background & Aims Chronic hyperammonemia induces neuroinflammation which mediates cognitive impairment. How hyperammonemia induces neuroinflammation remains unclear. We aimed to assess whether: chronic hyperammonemia induces peripheral inflammation, and whether this then contributes to neuroinflammation, altered neurotransmission and impaired spatial learning — before assessing whether this neuroinflammation and impairment is reversible following hyperammonemia elimination or treatment of peripheral inflammation with anti-TNF-α. Methods Chronic hyperammonemia was induced by feeding rats an ammonia-containing diet. Peripheral inflammation was analyzed by measuring PGE2, TNF-α, IL-6 and IL-10. We tested whether chronic anti-TNF-α treatment improves peripheral inflammation, neuroinflammation, membrane expression of glutamate receptors in the hippocampus and spatial learning. Results Hyperammonemic rats show a rapid and reversible induction of peripheral inflammation, with increased pro-inflammatory PGE2, TNF-α and IL-6, followed at around 10 days by reduced anti-inflammatory IL-10. Peripheral anti-TNF-α treatment prevents peripheral inflammation induction and the increase in IL-1b and TNF-α and microglia activation in hippocampus of the rats, which remain hyperammonemic. This is associated with prevention of the altered membrane expression of glutamate receptors and of the impairment of spatial memory assessed in the radial and Morris water mazes. Conclusions This report unveils a new mechanism by which chronic hyperammonemia induces neurological alterations: induction of peripheral inflammation. This suggests that reducing peripheral inflammation by safe procedures would improve cognitive function in patients with minimal hepatic encephalopathy. Lay summary This article unveils a new mechanism by which chronic hyperammonemia induces cognitive impairment in rats: chronic hyperammonemia per se induces peripheral inflammation, which mediates many of its effects on the brain, including induction of neuroinflammation, which alters neurotransmission, leading to cognitive impairment. It is also shown that reducing peripheral inflammation by treating rats with anti-TNF-α, which does not cross the blood-brain barrier, prevents hyperammonemia-induced neuroinflammation, alterations in neurotransmission and cognitive impairment.

Hyperammonemia is a main contributor to cognitive impairment and motor in-coordination in patients with hepatic encephalopathy. Hyperammonemia-induced neuroinflammation mediates the neurological alterations in hepatic encephalopathy. Intracerebral administration of extracellular cGMP restores some but not all types of cognitive impairment. Motor in-coordination, is mainly due to increased GABAergic tone in cerebellum. We hypothesized that extracellular cGMP would restore motor coordination in hyperammonemic rats by normalizing GABAergic tone in cerebellum and that this would be mediated by reduction of neuroinflammation. The aims of this work were to assess whether chronic intracerebral administration of cGMP to hyperammonemic rats: 1) restores motor coordination: 2) reduces neuroinflammation in cerebellum: 3) reduces extracellular GABA levels and GABAergic tone in cerebellum: and also 4) to provide some advance in the understanding on the molecular mechanisms involved. The results reported show that rats with chronic hyperammonemia show neuroinflammation in cerebellum, including microglia and astrocytes activation and increased levels of IL-1b and TNFa and increased membrane expression of the TNFa receptor. This is associated with increased glutaminase expression and extracellular glutamate, increased amount of the GABA transporter GAT-3 in activated astrocytes, increased extracellular GABA in cerebellum and motor in-coordination. Chronic intracerebral administration of extracellular cGMP to rats with chronic hyperammonemia reduces neuroinflammation, including microglia and astrocytes activation and membrane expression of the TNFa receptor. This is associated with reduced nuclear NF-kappa B, glutaminase expression and extracellular glutamate, reduced amount of the GABA transporter GAT-3 in activated astrocytes and reduced extracellular GABA in cerebellum and restoration of motor coordination. The data support that extracellular cGMP restores motor coordination in hyperammdnemic rats by reducing microglia activation and neuroinflammation, leading to normalization of extracellular glutamate and GABA levels in cerebellum and of motor coordination. (C) 2018 Elsevier Inc. All rights reserved.

The A beta protofibril selective antibody mAb158 prevents accumulation of A beta in astrocytes and rescues neurons from A beta induced apoptosis

Peripheral inflammation contributes to minimal hepatic encephalopathy in chronic liver diseases, which could be mediated by neuroinflammation. Neuroinflammation in cerebellum of patients with chronic liver diseases has not been studied in detail. Our aim was to analyze in cerebellum of patients with different grades of liver disease, from mild steatohepatitis to cirrhosis and hepatic encephalopathy: (a) neuronal density in Purkinje and granular layers; (b) microglial activation; (c) astrocyte activation; (d) peripheral lymphocytes infiltration; (e) subtypes of lymphocytes infiltrated. Steatohepatitis was classified as SH1, SH2 and SH3. Patients with SH1 show Th17 and Tfh lymphocytes infiltration in the meninges, microglia activation in the molecular layer and loss of 16 ± 4% of Purkinje and 19 ± 2% of granular neurons. White matter remains unaffected. With the progression of liver disease to worse stages (SH2, SH3, cirrhosis) activation of microglia and astrocytes extends to white matter, Bergman glia is damaged in the molecular layer and there is a further loss of Purkinje neurons. The results reported show that neuroinflammation in cerebellum occurs at early stages of liver disease, even before reaching cirrhosis. Neuroinflammation occurs earlier in the molecular layer than in white matter, and is associated with infiltration of peripheral Th17 and Tfh lymphocytes.

Chronic liver disease (e.g. cirrhosis) affects brain function. There is a high incidence of mild cognitive impairment and psychomotor slowing in patients with cirrhosis. This condition, known as minimal hepatic encephalopathy (MHE) affects more than 2 million people in the European Union and has serious health, social and economic consequences. There are no effective treatments for MHE. Rat models of MHE reproduce cognitive and motor alterations seen in patients, showing reduced performance in different types of cognitive tests, including learning a conditional discrimination task in a Y maze. Reduced ability to learn the Y maze task is due to reduced function of the glutamate -nitric oxide (NO)cGMP pathway in cerebellum, assessed in vivo by microclialysis. This results in reduced formation of cGMP in response to activation of NMDA receptors and impairment of learning ability. Both hyperammonemia and neuroinflammation contribute to impair this pathway. The effect is mediated by enhanced tonic activation of NMDA and GABAa receptors and of MAP-kinase p38. Based on these mechanistic studies new therapeutic strategies acting on specific targets in the brain have been designed and tested, which have successfully restored the function of the glutamate-NO-cGMP pathway in vivo and learning ability in rats with MHE. This can be achieved by therapeutic treatments using: a) phosphodiesterase 5 inhibitors (sildenafil, zaprinast), that increase cGMP levels by reducing its degradation b) extracellular cGMP c) antagonists of type A GABA receptors (bicuculline) d) neurosteroids that modulate GABAergic tone (pregnenolone sulfate) e) inhibitors of cyclooxygenase (ibuprofen) which reduce neuroinflammation f) inhibitors of MAP- kinase p38 (5[3239063), that reduce microglial activation and neuroinflammation Translation of some of these treatments to clinical practice would improve cognitive function, quality of life and life span of patients with cirrhosis and MHE and reduce health systems costs. Focal points: Benchside The mechanisms underlying cognitive and motor alterations in minimal hepatic encephalopathy (MHE) are beginning to be clarified in animal models. A number of therapeutic targets have been identified to improve cognitive and motor Function in MHE. Also, serum level of 3-nitrotyrosine is the first peripheral biomarker identified for diagnosis of MHE in cirrhotic patients, with high diagnostic accuracy, high sensitivity and specificity. Bedside In the European Union more than 2 million patients with liver cirrhosis show MHE with mild cognitive impairment. MHE is an important, until now underestimated, health, social and economic problem. Early diagnosis and treatment of MHE will significantly improve quality of life and life span of the patients and reduce costs of hospitalization and treatment Industry There are no specific treatments for the neurological alterations in MHE. A number of therapeutic targets have been identified in animal models to improve cognitive and motor function in MHE. This is a new market waiting for development of appropriate therapeutic treatments which would improve quality of life and survival of patients. Development of a kit for diagnosis of MHE in clinical practice is pending. Governments - regulatory agencies Early diagnosis and treatment of MHE will significantly improve quality of life and life span of the patients and reduce costs of hospitalization and treatment. Screening of the presence of MHE in patients with liver diseases will reduce costs. (C) 2014 European Society for Translational Medicine. Published by Elsevier Ltd. All rights reserved.

Several million patients with liver cirrhosis suffer minimal hepatic encephalopathy (MHE), with mild cognitive and coordination impairments that reduce their quality of life and life span. Hyperammonaemia and peripheral inflammation act synergistically to induce these neurological alterations. We propose that MHE appearance is because of the changes in peripheral immune system, which are transmitted to brain, leading to neuroinflammation that alters neurotransmission leading to cognitive and motor alterations. We summarize studies showing that MHE in cirrhotic patients is associated with alterations in the immune system and that patients died with HE show neuroinflammation in cerebellum, with microglial and astrocytic activation and Purkinje cell loss. We also summarize studies in animal models of MHE on the role of peripheral inflammation in neuroinflammation induction, how neuroinflammation alters neurotransmission and how this leads to cognitive and motor alterations. These studies identify therapeutic targets and treatments that improve cognitive and motor function. Rats with MHE show neuroinflammation in hippocampus and altered NMDA and AMPA receptor membrane expression, which impairs spatial learning and memory. Neuroinflammation in cerebellum is associated with altered GABA transporters and extracellular GABA, which impair motor coordination and learning in a Y maze. These alterations are reversed by treatments that reduce peripheral inflammation (anti-TNFα, ibuprofen), neuroinflammation (sulphoraphane, p38 inhibitors), GABAergic tone (bicuculline, pregnenolone sulphate) or increase extracellular cGMP (sildenafil or cGMP). The mechanisms identified would also occur in other chronic diseases associated with inflammation, aging and some mental and neurodegenerative diseases. Treatments that improve MHE may also be beneficial to treat these pathologies.

AimsPatients with liver disease may develop hepatic encephalopathy (HE), with cognitive impairment and motor in-coordination. Rats with HE due to portacaval shunts (PCS) show motor in-coordination. We hypothesized that in PCS rats: (i) Motor in-coordination would be due to enhanced GABAergic tone in cerebellum; (ii) increased GABAergic tone would be due to neuroinflammation; (iii) increasing cGMP would reduce neuroinflammation and GABAergic tone and restore motor coordination. To assess these hypotheses, we assessed if (i) treatment with sildenafil reduces neuroinflammation; (ii) reduced neuroinflammation is associated with reduced GABAergic tone and restored motor coordination. MethodsRats were treated with sildenafil to increase cGMP. Microglia and astrocytes activation were analyzed by immunohistochemistry, extracellular GABA by microdialysis, and motor coordination in the beam walking. ResultsPCS rats show neuroinflammation in cerebellum, with microglia and astrocytes activation, increased IL-1b and TNF-a and reduced YM-1 and IL-4. Membrane expression of the GABA transporter GAT1 is reduced, while GAT3 is increased. Extracellular GABA and motor in-coordination are increased. Sildenafil treatment eliminates neuroinflammation, microglia and astrocytes activation; changes in membrane expression of GABA transporters; and restores motor coordination. ConclusionsThis study supports an interplay between cGMP-neuroinflammation and GABAergic neurotransmission in impairing motor coordination in PCS rats.

Inflammation contributes to cognitive impairment in patients with hepatic encephalopathy (HE). However, the process by which peripheral inflammation results in cognitive impairment remains unclear. In animal models, neuroinflammation and altered neurotransmission mediate cognitive impairment. Taking into account these data, we hypothesized that in rats with HE: (1) peripheral inflammation is a main contributor to neuroinflammation; (2) neuroinflammation in hippocampus impairs spatial learning by altering AMPA and/or NMDA receptors membrane expression; (3) reducing peripheral inflammation with infliximab (anti-TNF-a) would improve spatial learning; (4) this would be associated with reduced neuroinflammation and normalization of the membrane expression of glutamate receptors. The aims of this work were to assess these hypotheses. We analyzed in rats with portacaval shunt (PCS) and control rats, treated or not with infliximab: (a) peripheral inflammation by measuring prostaglandin E2, IL10, IL-17, and IL-6; (b) neuroinflammation in hippocampus by analyzing microglial activation and the content of TNF-a and IL-1b; (c) AMPA and NMDA receptors membrane expression in hippocampus; and (d) spatial learning in the Radial and Morris water mazes. We assessed the effects of treatment with infliximab on peripheral inflammation, on neuroinflammation and AMPA and NMDA receptors membrane expression in hippocampus and on spatial learning and memory. PCS rats show increased serum prostaglandin E2, IL-17, and IL-6 and reduced IL-10 levels, indicating increased peripheral inflammation. PCS rats also show microglial activation and increased nuclear NF-kB and expression of TNF-a and IL-1b in hippocampus. This was associated with altered AMPA and NMDA receptors membrane expression in hippocampus and impaired spatial learning and memory in the radial and Morris water maze. Treatment with infliximab reduces peripheral inflammation in PCS rats, normalizing prostaglandin E2, IL-17, IL-6, and IL-10 levels in serum. Infliximab also prevents neuroinflammation, reduces microglial activation, translocates NF-kB into nucleoli and normalizes TNF-a and IL-1b content in hippocampus. This was associated with normalization of AMPA receptors membrane expression in hippocampus and of spatial learning and memory. The results suggest that peripheral inflammation contributes to spatial learning impairment in PCS rats. Treatment with anti-TNF-a could be a new therapeutic approach to improve cognitive function in patients with HE.

Background: Peripheral inflammation contributes to the neurological alterations in hepatic encephalopathy (HE). Neuroinflammation and altered GABAergic neurotransmission mediate cognitive and motor alterations in rats with HE. It remains unclear (a) if neuroinflammation and neurological impairment in HE are a consequence of peripheral inflammation and (b) how neuroinflammation impairs GABAergic neurotransmission. The aims were to assess in rats with HE whether reducing peripheral inflammation with anti-TNF-alpha (1) prevents cognitive impairment and motor in-coordination, (2) normalizes neuroinflammation and extracellular GABA in the cerebellum and also (3) advances the understanding of mechanisms linking neuroinflammation and increased extracellular GABA. Methods: Rats with HE due to portacaval shunt (PCS) were treated with infliximab. Astrocytes and microglia activation and TNF-alpha and IL-1 beta were analyzed by immunohistochemistry. Membrane expression of the GABA transporters GAT-3 and GAT-1 was analyzed by cross-linking with BS3. Extracellular GABA was analyzed by microdialysis. Motor coordination was tested using the beam walking and learning ability using the Y maze task. Results: PCS rats show peripheral inflammation, activated astrocytes, and microglia and increased levels of TNF-alpha and IL-1 beta. Membrane expression of GAT-3 and extracellular GABA are increased, leading to impaired motor coordination and learning ability. Infliximab reduces peripheral inflammation, microglia, and astrocyte activation and neuroinflammation and normalizes GABAergic neurotransmission, motor coordination, and learning ability. Conclusions: Neuroinflammation is associated with altered GABAergic neurotransmission and increased GAT-3 membrane expression and extracellular GABA (a); peripheral inflammation is a main contributor to the impairment of motor coordination and of the ability to learn the Y maze task in PCS rats (b); and reducing peripheral inflammation using safe procedures could be a new therapeutic approach to improve cognitive and motor function in patients with HE (c).

The cognitive and motor alterations in hepatic encephalopathy (HE) are the final result of altered neurotransmission and communication between neurons in neuronal networks and circuits. Different neurotransmitter systems cooperate to modulate cognitive and motor function, with a main role for glutamatergic and GABAergic neurotransmission in different brain areas and neuronal circuits. There is an interplay between glutamatergic and GABAergic neurotransmission alterations in cognitive and motor impairment in HE. This interplay may occur: (a) in different brain areas involved in specific neuronal circuits; (b) in the same brain area through cross-modulation of glutamatergic and GABAergic neurotransmission. We will summarize some examples of the (1) interplay between glutamatergic and GABAergic neurotransmission alterations in different areas in the basal ganglia-thalamus-cortex circuit in the motor alterations in minimal hepatic encephalopathy (MHE); (2) interplay between glutamatergic and GABAergic neurotransmission alterations in cerebellum in the impairment of cognitive function in MHE through altered function of the glutamate-nitric oxide-cGMP pathway. We will also comment the therapeutic implications of the above studies and the utility of modulators of glutamate and GABA receptors to restore cognitive and motor function in rats with hyperammonemia and hepatic encephalopathy. (C) 2014 Elsevier Ltd. All rights reserved.

Background: Hyperammonemia induces neuroinflammation and increases GABAergic tone in the cerebellum which contributes to cognitive and motor impairment in hepatic encephalopathy (HE). The link between neuroinflammation and GABAergic tone remains unknown. New treatments reducing neuroinflammation and GABAergic tone could improve neurological impairment. The aims were, in hyperammonemic rats, to assess whether: (a) Enhancing endogenous anti-inflammatory mechanisms by sulforaphane treatment reduces neuroinflammation and restores learning and motor coordination. (b) Reduction of neuroinflammation by sulforaphane normalizes extracellular GABA and glutamate-NO-cGMP pathway and identify underlying mechanisms. (c) Identify steps by which hyperammonemia-induced microglial activation impairs cognitive and motor function and how sulforaphane restores them. Methods: We analyzed in control and hyperammonemic rats, treated or not with sulforaphane, (a) learning in the Y maze; (b) motor coordination in the beam walking; (c) glutamate-NO-cGMP pathway and extracellular GABA by microdialysis; (d) microglial activation, by analyzing by immunohistochemistry or Western blot markers of proinflammatory (M1) (IL-1b, Iba-1) and anti-inflammatory (M2) microglia (Iba1, IL-4, IL-10, Arg1, YM-1); and (e) membrane expression of the GABA transporter GAT-3. Results: Hyperammonemia induces activation of astrocytes and microglia in the cerebellum as assessed by immunohistochemistry. Hyperammonemia-induced neuroinflammation is associated with increased membrane expression of the GABA transporter GAT-3, mainly in activated astrocytes. This is also associated with increased extracellular GABA in the cerebellum and with motor in-coordination and impaired learning ability in the Y maze. Sulforaphane promotes polarization of microglia from the M1 to the M2 phenotype, reducing IL-1b and increasing IL-4, IL-10, Arg1, and YM-1 in the cerebellum. This is associated with astrocytes deactivation and normalization of GAT-3 membrane expression, extracellular GABA, glutamate-nitric oxide-cGMP pathway, and learning and motor coordination. Conclusions: Neuroinflammation increases GABAergic tone in the cerebellum by increasing GAT-3 membrane expression. This impairs motor coordination and learning in the Y maze. Sulforaphane could be a new therapeutic approach to improve cognitive and motor function in hyperammonemia, hepatic encephalopathy, and other pathologies associated with neuroinflammation by promoting microglia differentiation from M1 to M2.