Multiple sclerosis (MS) is a chronic neuroinflammatory disease of the central nervous system (CNS) affecting nearly three million humans worldwide. In MS, cells of an auto-reactive immune system ...invade the brain and cause neuroinflammation. Neuroinflammation triggers a complex, multi-faceted harmful process not only in the white matter but also in the grey matter of the brain. In the grey matter, neuroinflammation causes synapse dysfunctions. Synapse dysfunctions in MS occur early and independent from white matter demyelination and are likely correlates of cognitive and mental symptoms in MS. Disturbed synapse/glia interactions and elevated neuroinflammatory signals play a central role. Glutamatergic excitotoxic synapse damage emerges as a major mechanism. We review synapse/glia communication under normal conditions and summarize how this communication becomes malfunctional during neuroinflammation in MS. We discuss mechanisms of how disturbed glia/synapse communication can lead to synapse dysfunctions, signaling dysbalance, and neurodegeneration in MS.
•Amyloid aggregates at pH 2 and pH 3.5 differed in their building blocks.•All aggregate building blocks changed towards smaller peptides after >48 h incubation.•Apparent dityrosine oxidation reached ...a maximum after 5 h incubation.•Protein carbonyls were not significantly increased during the first 5 h of fibril preparation.•The amyloid aggregates were deteriorated after 72 h incubation.
Although the connection between protein oxidation, amyloid aggregation and diseases such as Alzheimer’s is well known there is no information on such effects during preparation of beta-lactoglobulin fibrils. Different morphologies of amyloid aggregates of beta-lactoglobulin were prepared by incubation at pH 2 or pH 3.5 for up to 72 h. After 5 h, amyloid aggregates at pH 2 formed typical fibrils, which consisted of peptides. At pH 3.5, the amyloid aggregates were worm-like and consisted of intact protein. After 72 h, the building blocks at both pH values changed towards smaller peptides. The apparent tyrosine oxidation reached a maximum after 5 h at both pH values, whereas N-formylkynurenine and carbonyls increased continuously during 72 h. In case amyloid structures are used as edible material, the health related effects caused by protein oxidation needs to be considered.
We generated a novel Cre mouse strain for cell-specific deletion of floxed genes in ribbon synapse-forming retinal neurons. Previous studies have shown that the RIBEYE promotor targets the expression ...of recombinant proteins such as fluorescently tagged RIBEYE to photoreceptors and retinal bipolar cells and generates fluorescent synaptic ribbons in situ in these neurons. Here, we used the same promotor to generate a novel transgenic mouse strain in which the RIBEYE promotor controls the expression of a Cre-ER(T2) recombinase (RIBEYE-Cre). To visualize Cre expression, the RIBEYE-Cre animals were crossed with ROSA26 tau-GFP (R26-τGFP) reporter mice. In the resulting RIBEYE-Cre/R26 τGFP animals, Cre-mediated removal of a transcriptional STOP cassette results in the expression of green fluorescent tau protein (tau-GFP) that binds to cellular microtubules. We detected robust tau-GFP expression in retinal bipolar cells. Surprisingly, we did not find fluorescent tau-GFP expression in mouse photoreceptors. The lack of tau-GFP reporter protein in these cells could be based on the previously reported absence of tau protein in mouse photoreceptors which could lead to the degradation of the recombinant tau protein. Consistent with this, we detected Cre and tau-GFP mRNA in mouse photoreceptor slices by RT-PCR. The transgenic RIBEYE-Cre mouse strain provides a new tool to study the deletion of floxed genes in ribbon synapse-forming neurons of the retina and will also allow for analyzing gene deletions that are lethal if globally deleted in neurons.
Yield losses caused by fungal pathogens represent a major threat to global food production. One of the most devastating fungal wheat pathogens is Zymoseptoria tritici. Despite the importance of this ...fungus, the underlying mechanisms of plant-pathogen interactions are poorly understood. Here we present a conceptual framework based on coinfection assays, comparative metabolomics, and microbiome profiling to study the interaction of Z. tritici in susceptible and resistant wheat. We demonstrate that Z. tritici suppresses the production of immune-related metabolites in a susceptible cultivar. Remarkably, this fungus-induced immune suppression spreads within the leaf and even to other leaves, a phenomenon that we term "systemic induced susceptibility". Using a comparative metabolomics approach, we identify defense-related biosynthetic pathways that are suppressed and induced in susceptible and resistant cultivars, respectively. We show that these fungus-induced changes correlate with changes in the wheat leaf microbiome. Our findings suggest that immune suppression by this hemibiotrophic pathogen impacts specialized plant metabolism, alters its associated microbial communities, and renders wheat vulnerable to further infections.
Solvent-induced fibrillar aggregates of beta-lactoglobulin occur only in a certain balance between hydrophobic forces and electrostatic interactions. We hypothesize, that different hydrophobic ...solvent molecules as well as rising temperatures influence this equilibrium and thus the optimum to produce amyloid aggregates.
Dimethyl sulfoxide (DMSO), methanol and ethanol all resulted in polydisperse solutions with worm-like and spherical-aggregates, albeit to different degrees: the volume fraction required for aggregation was DMSO (50%) > methanol (40%) > ethanol (30%) which does not reflect their hydrophobicity. Further solvent addition decreased the fibrillar aggregation again. Increasing the temperature by 10–20 K decreased the solvent concentration needed to induce amyloid-like aggregates.
A targeted production of solvent-based amyloid-like aggregates is therefore not only dependent on the hydrophobicity of the solvents, but also on their direct interaction with the protein (denaturation).
•Amyloid-like aggregation occurs only at specific temperature-solvent combinations.•Elevated temperature increases the onset of solvent induced amyloid-like aggregation.•Intramolecular beta-sheet formation kinetics is slower than helix formation.•Worm-like aggregates occur together with spherical aggregates within 1–2 h.•The conditions could be used for a rapid production of functional fibrillar structures.
Multiple sclerosis (MS) is an inflammatory disease of the central nervous system that finally leads to demyelination. Demyelinating optic neuritis is a frequent symptom in MS. Recent studies also ...revealed synapse dysfunctions in MS patients and MS mouse models. We previously reported alterations of photoreceptor ribbon synapses in the experimental auto-immune encephalomyelitis (EAE) mouse model of MS. In the present study, we found that the previously observed decreased imunosignals of photoreceptor ribbons in early EAE resulted from a decrease in synaptic ribbon size, whereas the number/density of ribbons in photoreceptor synapses remained unchanged. Smaller photoreceptor ribbons are associated with fewer docked and ribbon-associated vesicles. At a functional level, depolarization-evoked exocytosis as monitored by optical recording was diminished even as early as on day 7 after EAE induction. Moreover compensatory, post-depolarization endocytosis was decreased. Decreased post-depolarization endocytosis in early EAE correlated with diminished synaptic enrichment of dynamin3. In contrast, basal endocytosis in photoreceptor synapses of resting non-depolarized retinal slices was increased in early EAE. Increased basal endocytosis correlated with increased de-phosphorylation of dynamin1. Thus, multiple endocytic pathways in photoreceptor synapse are differentially affected in early EAE and likely contribute to the observed synapse pathology in early EAE.
Recent rodent microbiome experiments suggest that besides Akkermansia, Parasutterella sp. are important in type 2 diabetes and obesity development. In the present translational human study, we aimed ...to characterize Parasutterella in our European cross-sectional FoCus cohort (n = 1,544) followed by validation of the major results in an independent Canadian cohort (n = 438). In addition, we examined Parasutterella abundance in response to a weight loss intervention (n = 55). Parasutterella was positively associated with BMI and type 2 diabetes independently of the reduced microbiome α/β diversity and low-grade inflammation commonly found in obesity. Nutritional analysis revealed a positive association with the dietary intake of carbohydrates but not with fat or protein consumption. Out of 126 serum metabolites differentially detectable by untargeted HPLC-based MS-metabolomics, L-cysteine showed the strongest reduction in subjects with high Parasutterella abundance. This is of interest, since Parasutterella is a known high L-cysteine consumer and L-cysteine is known to improve blood glucose levels in rodents. Furthermore, metabolic network enrichment analysis identified an association of high Parasutterella abundance with the activation of the human fatty acid biosynthesis pathway suggesting a mechanism for body weight gain. This is supported by a significant reduction of the Parasutterella abundance during our weight loss intervention. Together, these data indicate a role for Parasutterella in human type 2 diabetes and obesity, whereby the link to L-cysteine might be relevant in type 2 diabetes development and the link to the fatty acid biosynthesis pathway for body weight gain in response to a carbohydrate-rich diet in obesity development.
Breath analysis offers tremendous potential for diagnostic approaches, since it allows for easy and non-invasive sample collection. "Breathomics" as one major research field comprehensively analyses ...the metabolomic profile of exhaled breath providing insights into various (patho)physiological processes. Recent research, however, primarily focuses on volatile compounds. This is the first study that evaluates the non-volatile organic compounds (nVOCs) in breath following an untargeted metabolomic approach. Herein, we developed an innovative method utilizing a filter-based device for metabolite extraction. Breath samples of 101 healthy volunteers (female n = 50) were analysed using DI-FT-ICR-MS and biostatistically evaluated. The characterisation of the non-volatile core breathome identified more than 1100 metabolites including various amino acids, organic and fatty acids and conjugates thereof, carbohydrates as well as diverse hydrophilic and lipophilic nVOCs. The data shows gender-specific differences in metabolic patterns with 570 significant metabolites. Male and female metabolomic profiles of breath were distinguished by a random forest approach with an out-of-bag error of 0.0099. Additionally, the study examines how oral contraceptives and various lifestyle factors, like alcohol consumption, affect the non-volatile breathome. In conclusion, the successful application of a filter-based device combined with metabolomics-analyses delineate a non-volatile breathprint laying the foundation for discovering clinical biomarkers in exhaled breath.
Gut microbiota represent a potential novel target for future prediabetes and type 2 diabetes therapies. In that respect, niacin has been shown to beneficially affect the host-microbiome interaction ...in rodent models.
We characterized more than 500 human subjects with different metabolic phenotypes regarding their niacin (nicotinic acid NA and nicotinamide NAM) status and their gut microbiome. In addition, NA and NAM delayed-release microcapsules were engineered and examined in vitro and in vivo in two human intervention studies (bioavailability study and proof-of-concept/safety study).
We found a reduced α-diversity and
abundance in the microbiome of obese human subjects associated with a low dietary niacin intake. We therefore developed delayed-release microcapsules targeting the ileocolonic region to deliver increasing amounts of NA and NAM to the microbiome while preventing systemic resorption to avoid negative side effects (e.g., facial flushing). In vitro studies on these delayed-release microcapsules revealed stable conditions at pH 1.4, 4.5, and 6.8, followed by release of the compounds at pH 7.4, simulating the ileocolonic region. In humans in vivo, gut-targeted delayed-release NA but not NAM produced a significant increase in the abundance of
. In the absence of systemic side effects, these favorable microbiome changes induced by microencapsulated delayed-release NA were associated with an improvement of biomarkers for systemic insulin sensitivity and metabolic inflammation.
Targeted microbiome intervention by delayed-release NA might represent a future therapeutic option for prediabetes and type 2 diabetes.
Podocyte dysfunction, represented by foot process effacement and proteinuria, is often the starting point for progressive kidney disease. Therapies aimed at the cellular level of the disease are ...currently not available. Here we show that induction of urokinase receptor (uPAR) signaling in podocytes leads to foot process effacement and urinary protein loss via a mechanism that includes lipid-dependent activation of alphavbeta3 integrin. Mice lacking uPAR (Plaur-/-) are protected from lipopolysaccharide (LPS)-mediated proteinuria but develop disease after expression of a constitutively active beta3 integrin. Gene transfer studies reveal a prerequisite for uPAR expression in podocytes, but not in endothelial cells, for the development of LPS-mediated proteinuria. Mechanistically, uPAR is required to activate alphavbeta3 integrin in podocytes, promoting cell motility and activation of the small GTPases Cdc42 and Rac1. Blockade of alphavbeta3 integrin reduces podocyte motility in vitro and lowers proteinuria in mice. Our findings show a physiological role for uPAR signaling in the regulation of kidney permeability.
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Dostopno za:
DOBA, IJS, IZUM, KILJ, NUK, PILJ, PNG, SAZU, UILJ, UKNU, UL, UM, UPUK
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