α7 nicotinic acetylcholine receptor signaling modulates the inflammatory phenotype of fetal brain microglia: first evidence of interference by iron homeostasis.

Neuroinflammation in utero may result in life-long neurological disabilities. Microglia play a pivotal role, but the mechanisms are poorly understood. No early postnatal treatment strategies exist to enhance neuroprotective potential of microglia. We hypothesized that agonism on α7 nicotinic acetylcholine receptor (α7nAChR) in fetal microglia will augment their neuroprotective transcriptome profile, while the antagonistic stimulation of α7nAChR will achieve the opposite. Using an in vivo - in vitro model of developmental programming of neuroinflammation induced by lipopolysaccharide (LPS), we validated this hypothesis in primary fetal sheep microglia cultures re-exposed to LPS in presence of a selective α7nAChR agonist or antagonist. Our RNAseq and protein level findings show that a pro-inflammatory microglial phenotype acquired in vitro by LPS stimulation is reversed with α7nAChR agonistic stimulation. Conversely, antagonistic α7nAChR stimulation potentiates the pro-inflammatory microglial phenotype. Surprisingly, under conditions of LPS double-hit an interference of a postulated α7nAChR - ferroportin signaling pathway may impede this mechanism. These results suggest a therapeutic potential of α7nAChR agonists in early re-programming of microglia in neonates exposed to in utero inflammation via an endogenous cerebral cholinergic anti-inflammatory pathway. Future studies will assess the role of interactions between inflammation-triggered microglial iron sequestering and α7nAChR signaling in neurodevelopment.

[Nutrition and mental diseases : Focus depressive disorders]. / Ernährung und psychische Erkrankungen : Schwerpunkt depressive Störungen.

Dietary interventions are currently being discussed as additional treatment options for mental disorders. The pathological mechanisms are not yet fully understood. It is hypothesized that certain nutrients and dietary pattern influence immune and inflammatory processes, the microbiome, the leptin-melanocortinergic axis and hypothalamic-pituitary axis, as well as neurotransmitters of the cholinergic, noradrenergic, dopaminergic and serotonergic signaling cascades and neurotrophins. Observational studies have shown that traditional dietary patterns, such as the Mediterranean diet have a protective effect on mental health. Supplementation with long-chain polyunsaturated omega-3 fatty acids showed small to medium but significant effect sizes in meta-analyses from depression trials. The evidence with respect to the antidepressive effect of vitamin D supplementation is currently inconclusive.

RNAseq profiling of primary microglia and astrocyte cultures in near-term ovine fetus: A glial in vivo-in vitro multi-hit paradigm in large mammalian brain.

BACKGROUND: The chronically instrumented fetal sheep is a widely used animal model to study fetal brain development in health and disease, but no methods exist yet to interrogate dedicated brain cell populations to identify their molecular and genomic phenotype. For example, the molecular mechanisms whereby microglia or astrocytes contribute to inflammation in the brain remain incompletely understood. NEW METHOD: Here we present a protocol to derive primary pure microglial or astrocyte cultures from near-term fetal sheep brain, after the animals have been chronically instrumented and studied in vivo. Next, we present the implementation of whole transcriptome sequencing (RNAseq) pipeline to deeper elucidate the phenotype of such primary sheep brain glial cultures. RESULTS: We validate the new primary cultures method for cell purity and test the function of the glial cells on protein (IL-1ß) and transcriptome (RNAseq) levels in response to a lipopolysaccharide (LPS) challenge in vitro. COMPARISON WITH EXISTING METHODS: This method represents the first implementation of pure microglial or astrocytes cultures in fetal sheep brain. CONCLUSIONS: The presented approach opens new possibilities for testing not only supernatant protein levels in response to an in vitro challenge, but also to evaluate changes in the transcriptome of glial cells derived from a large mammalian brain bearing high resemblance to the human brain. Moreover, the presented approach lends itself to modeling the complex multi-hit paradigms of antenatal and perinatal cerebral insults in vivo and in vitro.

Evidence for three genetic loci involved in both anorexia nervosa risk and variation of body mass index.

The maintenance of normal body weight is disrupted in patients with anorexia nervosa (AN) for prolonged periods of time. Prior to the onset of AN, premorbid body mass index (BMI) spans the entire range from underweight to obese. After recovery, patients have reduced rates of overweight and obesity. As such, loci involved in body weight regulation may also be relevant for AN and vice versa. Our primary analysis comprised a cross-trait analysis of the 1000 single-nucleotide polymorphisms (SNPs) with the lowest P-values in a genome-wide association meta-analysis (GWAMA) of AN (GCAN) for evidence of association in the largest published GWAMA for BMI (GIANT). Subsequently we performed sex-stratified analyses for these 1000 SNPs. Functional ex vivo studies on four genes ensued. Lastly, a look-up of GWAMA-derived BMI-related loci was performed in the AN GWAMA. We detected significant associations (P-values <5 × 10-5, Bonferroni-corrected P<0.05) for nine SNP alleles at three independent loci. Interestingly, all AN susceptibility alleles were consistently associated with increased BMI. None of the genes (chr. 10: CTBP2, chr. 19: CCNE1, chr. 2: CARF and NBEAL1; the latter is a region with high linkage disequilibrium) nearest to these SNPs has previously been associated with AN or obesity. Sex-stratified analyses revealed that the strongest BMI signal originated predominantly from females (chr. 10 rs1561589; Poverall: 2.47 × 10-06/Pfemales: 3.45 × 10-07/Pmales: 0.043). Functional ex vivo studies in mice revealed reduced hypothalamic expression of Ctbp2 and Nbeal1 after fasting. Hypothalamic expression of Ctbp2 was increased in diet-induced obese (DIO) mice as compared with age-matched lean controls. We observed no evidence for associations for the look-up of BMI-related loci in the AN GWAMA. A cross-trait analysis of AN and BMI loci revealed variants at three chromosomal loci with potential joint impact. The chromosome 10 locus is particularly promising given that the association with obesity was primarily driven by females. In addition, the detected altered hypothalamic expression patterns of Ctbp2 and Nbeal1 as a result of fasting and DIO implicate these genes in weight regulation.

Are bidirectional associations of obesity and depression already apparent in childhood and adolescence as based on high-quality studies? A systematic review.

Our aim was to evaluate bidirectional associations of obesity and depression in cross-sectional and longitudinal studies with initial assessments in childhood or adolescence. The clarification of these relationships may support the development of innovative interventions, e.g. based on nutrition and mental health. A systematic literature search was conducted in MEDLINE. Main inclusion criteria were (i) assessment of subjects <18 years at baseline, (ii) use of validated psychometric instruments and (iii) elicitation of objectively measured anthropometric data at least at one time point. Twenty-four studies met our inclusion criteria. Out of 19, 14 cross-sectional studies confirmed a significant association of obesity and depression. Three out of eight longitudinal studies reported associations between obesity and subsequent depression in female children and adolescents only, and three out of nine studies obtained evidence in favour of the other direction with two studies revealing significant results only for female and one only for male children and adolescents. Evidence is mixed, and secure conclusions are hampered by the methodological variance of the included studies. Relationships are seemingly more readily detectable in female children adolescents and in the cross-sectional compared with the longitudinal analyses. Possibly, the joint development of obesity and depression in predisposed subjects accounts for the latter discrepancy.

Puma, but not noxa is essential for oligodendroglial cell death.

The mechanisms involved in oligodendroglial cell death in human demyelinating diseases are only partly understood. Here, we demonstrate that the BH3 only protein Puma, but not Noxa, is essential for oligodendroglial cell death in toxic demyelination induced by the copper chelator cuprizone. Primary oligodendrocytes derived from Noxa- or Puma-deficient mice showed comparable differentiation to wild-type cells, but Puma-deficient oligodendrocytes were less susceptible to spontaneous, staurosporine, or nitric oxide-induced cell death. Furthermore, Puma was expressed in oligodendrocytes in multiple sclerosis (MS) lesions and Puma mRNA levels were upregulated in primary human oligodendrocytes upon cell death induction by staurosporine. Our data demonstrate that Puma is pivotal for oligodendroglial cell death induced by different cell death stimuli and might play a role in oligodendroglial cell death in MS.

Weight-reducing side effects of the antiepileptic agents topiramate and zonisamide.

Drug-induced weight alteration can be a serious side effect that applies to several therapeutic agents and must be referred to in the respective approved labeling texts. The side effect may become health threatening in case of significant weight change in either direction. Several antiepileptic drugs (AEDs) are associated with weight gain such as gabapentin, pregabalin, valproic acid, and vigabatrin and to some extent carbamazepine. Others are weight neutral such as lamotrigine, levetiracetam, and phenytoin or associated with slight weight loss as, e.g., felbamate. The focus of this chapter is on the two AEDs causing strong weight loss: topiramate and zonisamide. For both drugs, several molecular mechanisms of actions are published. We provide a review of these potential mechanisms, some of which are based on in vivo studies in animal models for obesity, and of clinical studies exploring these two drugs as single entities or in combinations with other agents.

Ibipinabant attenuates ß-cell loss in male Zucker diabetic fatty rats independently of its effects on body weight.

AIM: To test the antidiabetic efficacy of ibipinabant, this new cannabinoid receptor 1 (CB1) antagonist was compared with food-restriction-induced weight loss, rosiglitazone (4 mg/kg) and rimonabant (3 and 10 mg/kg), using parameters of glycaemic control in male Zucker diabetic fatty (ZDF) rats. METHODS: Body weight, food and water intake, fasted and non-fasted glucose and insulin, glucose tolerance and glycosylated haemoglobin (HbA1c) were all assessed over the course of the 9-week study. Pancreatic insulin content and islet area were also evaluated. RESULTS: At the end of the study, vehicle-treated ZDF rats were severely hyperglycaemic and showed signs of ß-cell decline, including dramatic reductions in unfasted insulin levels. Ibipinanbant (10 mg/kg) reduced the following relative to vehicle controls: fasting glucose (-61%), glucose excursion area under the curve (AUC) in an oral glucose tolerance test (OGTT, -44%) and HbA1c (-50%). Furthermore, non-fasting insulin, islet area and islet insulin content were all increased (71, 40 and 76%, respectively) relative to vehicle controls by the end of the study. All of these effects were similar to those of rimonabant and rosiglitazone, where ibipinabant was slightly more effective than rimonabant at the lowest dose and somewhat less effective than rosiglitazone at all doses. These antidiabetic effects appear independent of weight loss because none of the parameters above were consistently improved by the comparable weight loss induced by food restriction. CONCLUSIONS: Ibipinabant may have weight loss-independent antidiabetic effects and may have the potential to attenuate ß-cell loss in a model of progressive ß-cell dysfunction.

Clinical immunology of the sphingosine 1-phosphate receptor modulator fingolimod (FTY720) in multiple sclerosis.

The oral sphingosine 1-phosphate (S1P) receptor (S1PR) modulator fingolimod has been shown to be effective in the treatment of patients with relapsing multiple sclerosis (MS). The drug binds with high affinity to 4 of the 5 G-protein-coupled S1P receptors (S1P(1-5)). After binding, the receptors are internalized, degraded, and thus functionally antagonized by fingolimod. Under physiologic conditions, S1P(1) mediates the egress of lymphocytes from secondary lymphoid organs to the peripheral circulation. Functional antagonism of S1P(1) by fingolimod results in a reduction in peripheral lymphocyte counts by inhibiting egress of lymphocytes, including potentially encephalitogenic T cells and their naïve progenitors that would otherwise be present within the circulation. Despite the fingolimod-mediated reduction of lymphocyte counts, fingolimod-treated patients with MS have been shown to have few infections and related complications and were able to mount antigen-specific immune responses in vaccination studies.

Strategy for anti-aquaporin-4 auto-antibody identification and quantification using a new cell-based assay.

NMO-IgG is a specific biomarker of neuromyelitis optica (NMO) that targets the aquaporin-4 (AQP4) water channel protein. The current gold standard for NMO-IgG identification is indirect immunofluorescence (IIF). Our aim in this study was to develop a new quantitative cell-based assay (CBA) and to propose a rational strategy for anti-AQP4 Ab identification and quantification. We observed an excellent correlation between the CBA and IIF for NMO-IgG/anti-AQP4 detection. The CBA appeared more sensitive than IIF but on the other hand, IIF allows the simultaneous detection of various auto-Abs, underlining the complementarity between both methods. In conclusion, we propose to use IIF for the screening of patients at diagnosis in order to identify auto-Abs targeting the central nervous system. A highly sensitive, AQP4 specific and quantitative assay such as our CBA could be used thereafter to specifically identify the target of the Ab and to monitor its serum concentration under treatment.

TLR-mediated B cell activation results in ectopic CLIP expression that promotes B cell-dependent inflammation.

Infectious pathogens produce compounds called Toll ligands that activate TLRs on lymphocytes. Acute activation triggered by certain TLRs appears to "jump start" the innate immune response, characterized by the release of inflammatory cytokines and cellular expansion. In some individuals, there is a failure to control acute inflammation, resulting in postinfectious, chronic inflammation. Susceptibility to chronic inflammation is strongly associated with an individual's MHC genes. Recent clinical trials for several autoimmune diseases characterized by chronic inflammation suggest that B lymphocyte depletion therapies dampen chronic immune activation. However, currently, there is no known mechanism that accounts for the correlation among TLR activation, MHC genetics, and a pathological role for B-lymphocytes. Our hypothesis is that TLR-activated B cells (B cells that have been polyclonally activated in the absence of antigen-specific signals) are not controlled properly by T cell-dependent B cell death, thereby causing B cell-dependent chronic inflammation. Here, we show that treatment with Toll ligands results in polyclonal B cell activation accompanied by ectopic expression of CLIP. Furthermore, by adoptively transferring purified CLIP+ B cells in syngeneic animals, we find that CLIP+ B cells induce production of TNF-α by host T cells. Finally, we demonstrate that CLIP-targeted peptide competition results in the death of polyclonally activated CLIP+ B cells.

Glatiramer acetate-reactive T lymphocytes regulate oligodendrocyte progenitor cell number in vitro: role of IGF-2.

Glatiramer acetate (GA) is an immunomodulator approved for therapy of relapsing-remitting multiple sclerosis (RRMS), but recent findings indicate that it may also have additional, neurotrophic effects. Here, we found that supernatants from human GA-reactive T lymphocytes potentiated oligodendrocyte numbers in rodent and human oligodendrocyte progenitor (OPC) cultures. Effects of Th2-polarized lines were stronger than Th1-polarized cells. Microarray and ELISA analyses revealed that neurotrophic factors induced in Th2- and Th1-polarized GA-reactive lines included IGF-2 and BMP-7 respectively, and functional studies confirmed IGF-2 as trophic for OPCs. Our results support the concept that GA therapy may result in supportive effects on oligodendrocytes in RRMS patients.

Phase II study of oral fingolimod (FTY720) in multiple sclerosis: 3-year results.

In a 6-month, placebo-controlled trial, oral fingolimod (FTY720) 1.25 or 5.0 mg, once daily, significantly reduced MRI inflammatory activity and annualized relapse rate compared with placebo in patients with relapsing multiple sclerosis (MS). The objectives were to monitor the 36-month, interim efficacy and safety results of the ongoing extension of this study. In the extension (months 7-36), placebo-treated patients were re-randomized to either dose of fingolimod; fingolimod-treated patients continued at the same dose. During months 15-24, all patients receiving fingolimod 5.0 mg switched to 1.25 mg. Of the 250 patients who entered the extension study, 173 (69%) continued to month 36. Most patients were free from gadolinium-enhanced lesions (88-89%) or new T2 lesions (70-78%) at month 36. Patients receiving continuous fingolimod treatment had sustained low annualized relapse rates of 0.20-0.21, and 68-73% remained relapse-free at month 36. Over 36 months, nasopharyngitis (34%), headache (30%), fatigue (19%) and influenza (18%) were the most commonly reported adverse events. Pulmonary function remained stable and blood pressure was stable after an initial increase (3-5 mmHg) during the first 6 months of fingolimod treatment; serious adverse events included infections and skin cancer. The low MRI and clinical disease activity at 6 months were maintained at 36 months with fingolimod, which was generally well tolerated by most patients. The efficacy and safety of oral fingolimod are being further evaluated in a large phase III MS study programme.

Gender differences in the histopathology of MS?

Multiple sclerosis (MS) lesions are histopathologically characterized by inflammation, demyelination/remyelination, axonal damage and gliosis. Animal experimental and in vitro studies suggest that sex hormones influence the immune system and contribute to the increased likelihood in women of developing MS. However, a variety of studies have also shown that remyelination is more marked in female rodents or that female sex hormones are beneficial for myelin repair. To determine whether gender influences the histopathology of MS lesions, we compared the extent of inflammation, axonal damage and remyelination in MS lesions of female and male MS patients. We observed no differences in the composition of inflammatory infiltrates, axonal damage or cortical pathology. Similar numbers of oligodendroglial progenitor cells and mature oligodendrocytes were present in MS lesions. Remyelination is slightly, but not significantly, more extensive in women than men in early MS lesions. The absence of significant differences in lesion pathology between female and male MS patients might be explained by a lack of a gender influence, but also might be due to the limited number of tissue samples available for histopathological analysis.

Remyelination capacity of the MS brain decreases with disease chronicity.

OBJECTIVE: To analyze and compare the extent of remyelination in lesions from patients with multiple sclerosis (MS) who have a short (early MS lesions) or a long (chronic MS lesions) disease duration and to determine the influence of anatomic localization on the extent of remyelination. In early MS lesions, remyelination has been described as a relatively frequent event, in contrast to chronic MS lesions, where remyelination is absent or limited to the lesion border in the majority of lesions. However, no studies have been published that have quantified and compared the extent of remyelination in early and chronic MS lesions. METHODS: We analyzed the occurrence of remyelination in 52 biopsies from 51 patients (early MS) and in 174 lesions from 36 autopsy cases (chronic MS) by immunohistochemistry for myelin proteins, and correlated our findings with anatomic localization, sex, age, and disease duration. RESULTS: Significantly more lesions were remyelinated in early than in chronic MS (80.7% vs 60%). In chronic MS, subcortical lesions showed more extensive remyelination than periventricular lesions. The majority of cerebellar lesions were completely demyelinated. CONCLUSION: In summary, our data demonstrate that remyelination is a frequent event in early multiple sclerosis lesions. Furthermore, the anatomic localization of a lesion might influence the extent of remyelination.

Oral fingolimod (FTY720) in multiple sclerosis: two-year results of a phase II extension study.

OBJECTIVE: To report the results of a 24-month extension of a phase II trial assessing the efficacy, safety, and tolerability of the once-daily oral sphingosine-1-phosphate receptor modulator, fingolimod (FTY720), in relapsing multiple sclerosis (MS). METHODS: In the randomized, double-blind, placebo-controlled core study, 281 patients received placebo or FTY720, 1.25 or 5.0 mg/day, for 6 months. During the subsequent dose-blinded extension, patients assigned to placebo were re-randomized to either dose of FTY720; those originally assigned to FTY720 continued at the same dose. Patients receiving FTY720 5.0 mg were switched to 1.25 mg during the month 15 to month 24 study visits. RESULTS: Of 281 patients randomized in the core study, 250 (89%) entered the extension phase, and 189 (75.6%) received treatment for 24 months. During the core study, FTY720 significantly reduced gadolinium-enhanced (Gd(+)) lesions and annualized relapse rate (ARR) compared with placebo, with no differences between doses. During the extension phase, patients who switched from placebo to FTY720 showed clear reductions in ARR and lesion counts compared with the placebo phase; ARR and lesion counts remained low in patients who continued FTY720 treatment. After 24 months, 79 to 91% of patients were free from Gd(+) lesions and up to 77% of patients remained relapse free. FTY720 was well tolerated; no new safety concerns emerged during months 7 to 24 compared with the 6-month core study. CONCLUSIONS: Once-daily oral treatment with FTY720, 1.25 or 5.0 mg, for up to 2 years, was well tolerated and was associated with low relapse rates and lesion activity.