Institut für Ernährungsmedizin

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Oral intake of the microalgae Nannochloropsis oceanica, Chlorella vulgaris, or Phaeodactylum tricornutum improves metabolic conditions in hypercaloric-fed mice
(2024) Kopp, Lena; Seethaler, Benjamin; Neumann, Ulrike; Bischoff, Stephan C.
Diet-induced metabolic load is associated with excess body weight and liver steatosis. Here, selected microalgae, known to contain bioactive nutrients, were studied for beneficial metabolic effects in a mouse model of liver steatosis. Adult mice (8 per group) were fed either a Western-style diet (WSD) or a control diet +/ 15 % of the microalgae Chlorella vulgaris (CV), Nannochloropsis oceanica (NO), or Phaeodactylum tricornutum (PT) for 12 weeks. We evaluated liver fat content and liver damage, as well as fecal microbiota and lipopolysaccharide (LPS) translocation. NO supplementation to a WSD reduced the grade of liver steatosis (from 17 % to 4.7 %, p < 0.002), the liver damage score (p < 0.001), and LPS translocation (p < 0.001). PT had similar effects on liver damage score (p < 0.001) and LPS translocation (p < 0.001). CV supplementation reduced LPS translocation (p < 0.001). In conclusion, dietary supplementation of microalgae may be a novel sustainable approach to combat metabolic loads.
No difference in tolerance between wheat and spelt bread in patients with suspected non-celiac wheat sensitivity
(2022) Zimmermann, Julia; Longin, Friedrich H.; Schweinlin, Anna; Basrai, Maryam; Bischoff, Stephan C.
Individuals with suspected non-celiac wheat sensitivity (NCWS) often report better tolerance of spelt (Triticum aestivum ssp. spelta) compared to wheat (Triticum aestivum ssp. aestivum) bakery products. This experience has neither been validated nor explained on a molecular level. Therefore, we performed blinded wheat and spelt bread challenge in this patient group. Twenty-four adults with a history of NCWS but suspected spelt tolerance were challenged in a single-blinded crossover design over six weeks with six different study breads each at 300 g per day for 4 days followed by a washout phase of 3 days. Study breads comprised spelt and wheat breads made either after a traditional (T) or a current (C) recipe, resulting in four bread types plus a gluten-free bread with 1.5% added oligosaccharides (+FODMAP) and a gluten-free bread with 5% added wheat gluten (+Gluten). The main outcome parameter was the Irritable Bowel Syndrome—Severity Scoring System, which was higher than self-estimated by the participants after spelt bread consumption (p = 0.002 for T; p = 0.028 for C) and lower for wheat bread (p = 0.052 for T; p = 0.007 for C), resulting in no difference between wheat and spelt bread tolerance. The +FODMAP bread was better tolerated than both T breads (p = 0.003 for spelt; p = 0.068 for wheat) and equally well tolerated as both C breads and +Gluten breads after normalization to the washout scores. Neither signs of inflammation nor markers for intestinal barrier integrity were influenced. Our data do not confirm, on an objective basis, the differences in expected symptoms resulting from wheat and spelt products, suggesting a strong nocebo effect for wheat and a placebo effect for spelt.
Serotonin receptor 5-HT2A regulates TrkB receptor function in heteroreceptor complexes
(2022) Ilchibaeva, Tatiana; Tsybko, Anton; Zeug, Andre; Müller, Franziska E.; Guseva, Daria; Bischoff, Stephan; Ponimaskin, Evgeni; Naumenko, Vladimir
Serotonin receptor 5-HT2A and tropomyosin receptor kinase B (TrkB) strongly contribute to neuroplasticity regulation and are implicated in numerous neuronal disorders. Here, we demonstrate a physical interaction between 5-HT2A and TrkB in vitro and in vivo using co-immunoprecipitation and biophysical and biochemical approaches. Heterodimerization decreased TrkB autophosphorylation, preventing its activation with agonist 7,8-DHF, even with low 5-HT2A receptor expression. A blockade of 5-HT2A receptor with the preferential antagonist ketanserin prevented the receptor-mediated downregulation of TrkB phosphorylation without restoring the TrkB response to its agonist 7,8-DHF in vitro. In adult mice, intraperitoneal ketanserin injection increased basal TrkB phosphorylation in the frontal cortex and hippocampus, which is in accordance with our findings demonstrating the prevalence of 5-HT2A–TrkB heteroreceptor complexes in these brain regions. An expression analysis revealed strong developmental regulation of 5-HT2A and TrkB expressions in the cortex, hippocampus, and especially the striatum, demonstrating that the balance between TrkB and 5-HT2A may shift in certain brain regions during postnatal development. Our data reveal the functional role of 5-HT2A–TrkB receptor heterodimerization and suggest that the regulated expression of 5-HT2A and TrkB is a molecular mechanism for the brain-region-specific modulation of TrkB functions during development and under pathophysiological conditions.
Gut microbiota patterns predicting long-term weight loss success in individuals with obesity undergoing nonsurgical therapy
(2022) Bischoff, Stephan C.; Nguyen, Nguyen K.; Seethaler, Benjamin; Beisner, Julia; Kügler, Philipp; Stefan, Thorsten
The long-term success of nonsurgical weight reduction programs is variable; thus, predictors of outcome are of major interest. We hypothesized that the intestinal microbiota known to be linked with diet and obesity contain such predictive elements. Methods: Metagenome analysis by shotgun sequencing of stool DNA was performed in a cohort of 15 adults with obesity (mean body mass index 43.1 kg/m2) who underwent a one-year multidisciplinary weight loss program and another year of follow-up. Eight individuals were persistently successful (mean relative weight loss 18.2%), and seven individuals were not successful (0.2%). The relationship between relative abundancies of bacterial genera/species and changes in relative weight loss or body mass index was studied using three different statistical modeling methods. Results: When combining the predictor variables selected by the applied statistical modeling, we identified seven bacterial genera and eight bacterial species as candidates for predicting success of weight loss. By classification of relative weight-loss predictions for each patient using 2–5 term models, 13 or 14 out of 15 individuals were predicted correctly. Conclusions: Our data strongly suggest that gut microbiota patterns allow individual prediction of long-term weight loss success. Prediction accuracy seems to be high but needs confirmation by larger prospective trials.
Vitamin A- and D-deficient diets disrupt intestinal antimicrobial peptide defense involving Wnt and STAT5 signaling pathways in mice
(2023) Filipe Rosa, Louisa; Petersen, Patricia P.; Görtz, Lisa F.; Stolzer, Iris; Kaden-Volynets, Valentina; Günther, Claudia; Bischoff, Stephan C.
Vitamin A and D deficiencies are associated with immune modulatory effects and intestinal barrier impairment. However, the underlying mechanisms remain unclear. C57BL/6J mice were fed either a diet lacking in vitamin A (VAd), vitamin D (VDd) or a control diet (CD) for 12 weeks. Gut barrier function, antimicrobial peptide (AMP) defense and regulatory pathways were assessed. VAd mice compared to CD mice showed a reduced villus length in the ileum (p < 0.01) and decreased crypt depth in the colon (p < 0.05). In both VAd- and VDd-fed mice, ileal α-defensin 5 (p < 0.05/p < 0.0001 for VAd/VDd) and lysozyme protein levels (p < 0.001/p < 0.0001) were decreased. Moreover, mRNA expression of lysozyme (p < 0.05/p < 0.05) and total cryptdins (p < 0.001/p < 0.01) were reduced compared to controls. Furthermore, matrix metalloproteinase-7 (Mmp7) mRNA (p < 0.0001/p < 0.001) as well as components of the Wnt signaling pathway were decreased. VAd- and VDd-fed mice, compared to control mice, exhibited increased expression of pro-inflammatory markers and β-defensins in the colon. Organoid cell culture confirmed that vitamins A and D regulate AMP expression, likely through the Jak/STAT5 signaling pathway. In conclusion, our data show that vitamin A and D regulate intestinal antimicrobial peptide defense through Wnt and STAT5 signaling pathways.
Editorial: Updates on RIG-I-like receptor-mediated innate immune responses
(2023) Kishore, Uday; Kufer, Thomas A.
Inflammation and nutrition: friend or foe?
(2023) Stumpf, Franziska; Keller, Bettina; Gressies, Carla; Schuetz, Philipp
The importance of the interplay between inflammation and nutrition has generated much interest in recent times. Inflammation has been identified as a key driver for disease-related malnutrition, leading to anorexia, reduced food intake, muscle catabolism, and insulin resistance, which are stimulating a catabolic state. Interesting recent data suggest that inflammation also modulates the response to nutritional treatment. Studies have demonstrated that patients with high inflammation show no response to nutritional interventions, while patients with lower levels of inflammation do. This may explain the contradictory results of nutritional trials to date. Several studies of heterogeneous patient populations, or in the critically ill or advanced cancer patients, have not found significant benefits on clinical outcome. Vice versa, several dietary patterns and nutrients with pro- or anti-inflammatory properties have been identified, demonstrating that nutrition influences inflammation. Within this review, we summarize and discuss recent advances in both the role of inflammation in malnutrition and the effect of nutrition on inflammation.
How does dietary intake relate to dispositional optimism and health-related quality of life in germline BRCA1/2 mutation carriers?
(2023) Esser, Anne; Neirich, Leonie; Grill, Sabine; Bischoff, Stephan C.; Halle, Martin; Siniatchkin, Michael; Yahiaoui-Doktor, Maryam; Kiechle, Marion; Lammert, Jacqueline
Background: The Mediterranean diet (MD) is an anti-inflammatory diet linked to improved health-related quality of life (HRQoL). Germline (g)BRCA1/2 mutation carriers have an increased risk of developing breast cancer and are often exposed to severe cancer treatments, thus the improvement of HRQoL is important. Little is known about the associations between dietary intake and HRQoL in this population. Methods: We included 312 gBRCA1/2 mutation carriers from an ongoing prospective randomized controlled lifestyle intervention trial. Baseline data from the EPIC food frequency questionnaire was used to calculate the dietary inflammatory index (DII), and adherence to MD was captured by the 14-item PREDIMED questionnaire. HRQoL was measured by the EORTC QLQ-C30 and LOT-R questionnaires. The presence of metabolic syndrome (MetS) was determined using anthropometric measurements, blood samples and vital parameters. Linear and logistic regression models were performed to assess the possible impact of diet and metabolic syndrome on HRQoL. Results: Women with a prior history of cancer (59.6%) reported lower DIIs than women without it (p = 0.011). A greater adherence to MD was associated with lower DII scores (p < 0.001) and reduced odds for metabolic syndrome (MetS) (p = 0.024). Women with a more optimistic outlook on life reported greater adherence to MD (p < 0.001), whereas a more pessimistic outlook on life increased the odds for MetS (OR = 1.15; p = 0.023). Conclusions: This is the first study in gBRCA1/2 mutation carriers that has linked MD, DII, and MetS to HRQoL. The long-term clinical implications of these findings are yet to be determined.
NLRC5-CIITA fusion protein as an effective inducer of MHC-I expression and antitumor immunity
(2023) Santharam, Madanraj Appiya; Shukla, Akhil; Levesque, Dominique; Kufer, Thomas A.; Boisvert, François-Michel; Ramanathan, Sheela; Ilangumaran, Subburaj
Aggressive tumors evade cytotoxic T lymphocytes by suppressing MHC class-I (MHC-I) expression that also compromises tumor responsiveness to immunotherapy. MHC-I defects strongly correlate to defective expression of NLRC5, the transcriptional activator of MHC-I and antigen processing genes. In poorly immunogenic B16 melanoma cells, restoring NLRC5 expression induces MHC-I and elicits antitumor immunity, raising the possibility of using NLRC5 for tumor immunotherapy. As the clinical application of NLRC5 is constrained by its large size, we examined whether a smaller NLRC5-CIITA fusion protein, dubbed NLRC5-superactivator (NLRC5-SA) as it retains the ability to induce MHC-I, could be used for tumor growth control. We show that stable NLRC5-SA expression in mouse and human cancer cells upregulates MHC-I expression. B16 melanoma and EL4 lymphoma tumors expressing NLRC5-SA are controlled as efficiently as those expressing full-length NLRC5 (NLRC5-FL). Comparison of MHC-I-associated peptides (MAPs) eluted from EL4 cells expressing NLRC5-FL or NLRC5-SA and analyzed by mass spectrometry revealed that both NLRC5 constructs expanded the MAP repertoire, which showed considerable overlap but also included a substantial proportion of distinct peptides. Thus, we propose that NLRC5-SA, with its ability to increase tumor immunogenicity and promote tumor growth control, could overcome the limitations of NLRC5-FL for translational immunotherapy applications.
NOD-like receptors - emerging links to obesity and associated morbidities
(2023) Bauer, Sarah; Hezinger, Lucy; Rexhepi, Fjolla; Ramanathan, Sheela; Kufer, Thomas A.
Obesity and its associated metabolic morbidities have been and still are on the rise, posing a major challenge to health care systems worldwide. It has become evident over the last decades that a low-grade inflammatory response, primarily proceeding from the adipose tissue (AT), essentially contributes to adiposity-associated comorbidities, most prominently insulin resistance (IR), atherosclerosis and liver diseases. In mouse models, the release of pro-inflammatory cytokines such as TNF-alpha (TNF-α) and interleukin (IL)-1β and the imprinting of immune cells to a pro-inflammatory phenotype in AT play an important role. However, the underlying genetic and molecular determinants are not yet understood in detail. Recent evidence demonstrates that nucleotide-binding and oligomerization domain (NOD)-like receptor (NLR) family proteins, a group of cytosolic pattern recognition receptors (PRR), contribute to the development and control of obesity and obesity-associated inflammatory responses. In this article, we review the current state of research on the role of NLR proteins in obesity and discuss the possible mechanisms leading to and the outcomes of NLR activation in the obesity-associated morbidities IR, type 2 diabetes mellitus (T2DM), atherosclerosis and non-alcoholic fatty liver disease (NAFLD) and discuss emerging ideas about possibilities for NLR-based therapeutic interventions of metabolic diseases.
Benefits of fiber-enriched foods on satiety and parameters of human well-being in adults with and without cardiometabolic risk
(2023) Ehret, Janine; Brandl, Beate; Schweikert, Karsten; Rennekamp, Rachel; Ströbele-Benschop, Nanette; Skurk, Thomas; Hauner, Hans
Consumption of fiber-rich foods is linked to beneficial effects on chronic diseases and gut health, while implications towards improving satiety and parameters of well-being remain unclear. A randomized placebo-controlled intervention study was conducted to compare the effects of fiber-enriched foods to their non-enriched counterparts in adults over a 12-week period on selected clinical parameters—satiety, quality of life, body sensation, and life satisfaction—subjective health status, and importance of diet for well-being. Quality of life (QOL) differed significantly between intervention and control groups at baseline, throughout, and at the end of the study. No effects on satiety, satisfaction with life, or the importance of diet for well-being could be shown between groups. With higher fiber intake, body sensation ratings increased. A higher BMI was significantly associated with lower-body sensation, subjective health status and quality of life. Fiber-enriched foods do not seem to affect feeling of satiety or parameters of well-being. Larger samples and additional methods are necessary to fully explore the effect of increased fiber intake on patient-related outcomes in more detail.
Serotonin reuptake transporter deficiency promotes liver steatosis and impairs intestinal barrier function in obese mice fed a Western‐style diet
(2023) Rosa, Louisa Filipe; Haasis, Eva; Knauss, Annkathrin; Guseva, Daria; Bischoff, Stephan C.
Background: Intestinal barrier dysfunctions have been associated with liver steatosis and metabolic diseases. Besides nutritional factors, like a Western-style diet (WSD), serotonin has been linked with leaky gut. Therefore, we aimed to evaluate the role of serotonin in the pathogenesis of intestinal barrier dysfunctions and liver steatosis in mice fed high-fat and high-sugar diets. Methods: 6–8 weeks old male serotonin reuptake transporter knockout mice (SERT−/−) and wild-type controls (SERT+/+) were fed either a WSD or a control diet (CD) ad libitum with or without fructose 30% (F) added to the drinking water for 12 weeks. Markers of liver steatosis and intestinal barrier function were assessed. Key Results: SERT−/− mice showed increased weight gain compared with SERT+/+ mice when fed a WSD ± F for 12 weeks (p < 0.05), whereby SERT−/− mice exhibited reduced energy (−21%) intake. Furthermore, SERT knockout resulted in a more pronounced liver steatosis (p < 0.05), enhanced levels of endotoxin in portal vein plasma (p < 0.05), and increased liver expression of Tnf and Myd88 (p < 0.05), when mice were fed a WSD ± F. Finally, SERT−/− mice, when compared with SERT+/+ mice, had a decreased mRNA expression of Muc2 (p < 0.01), Ocln (p < 0.05), Cldn5 (p = 0.054) and 7 (p < 0.01), Defa5 (p < 0.05) and other antimicrobial peptides in the ileum. On the protein level, ZO-1 (p < 0.01) and DEFA5 protein (p < 0.0001) were decreased. Conclusion and Inferences: Our data demonstrate that SERT knockout causes weight gain, liver steatosis, and leaky gut, especially in mice fed a WSD. Therefore, SERT induction could be a novel therapeutic approach to improve metabolic diseases associated with intestinal barrier dysfunction.
The influence of knowledge about the environmental impact of foods on consumers' decisions and perceptions
(2024) Bschaden, Andreas; Ströbele-Benschop, Nanette
Food production substantially impacts the environment, with large differences between foods, dishes, and dietary styles. Therefore, consumer behaviour is an important issue in sustainability research. Several theories attempt to explain consumer behaviour, such as the Theory of Planned Behaviour or the transtheoretical model. In both models, attitudes play a central role in explaining behaviour. Attitudes are in part influenced by knowledge, and by information individuals are exposed to. This dissertation project aimed to enhance the understanding of the interplay between consumers’ knowledge and dietary behaviour, with the focus on ecological sustainability. Three studies were conducted, each focusing on diverse aspects. First, the project investigated how aware the participants are about the environmental impact of meat consumption, and how two informative videos could influence that knowledge, as well as participants’ meat consumption. Second, the hedonic perception of a snack that was offered under different sustainability information conditions was explored. Third, the impact of carbon footprint information of dishes on food choices, as well as participants’ perception of that information was examined. The first study assessed participants’ knowledge regarding the environmental benefits of various dietary strategies, such as purchasing regional, seasonal, and organic foods, avoiding plastic packaging and foods imported by airplane, and eating less meat. Additionally, an intervention using three kinds of informative videos was conducted to investigate the impact of the provided information on the participants’ knowledge. Data were collected through a questionnaire before and after the intervention. The second study examined consumers’ hedonic perception of a novel savoury tortilla-chips shaped snack made from by-products of the food industry. The snack was offered to a sample of participants under two varying information conditions to investigate how information about the snack’s ingredients, its sustainability with general information about food losses compared to tasting the snack without such information, influenced the hedonic experience. The third study investigated the influence of displaying the carbon footprint of dishes on dish choices across various gastronomic settings and with visually different presentation methods. In addition to sales figures, customer perceptions of the provided information were also evaluated, gathered through a survey. Results suggest that consumers still underestimate the environmental benefit of eating less meat, both in general and compared to other strategies. While this result applies for all investigated groups, there were significant differences between gender and educational groups. The documentary about the environmental impact of meat consumption led to higher assessments of the environmental benefit of eating less meat a week later, but no effect was observed a year later. No such effect was observed for the educational video about the same topic, nor for the control video. Regarding the perception of a savoury snack under different information conditions, the MANOVA model showed significant effects for study condition on perceived saltiness, for gender on willingness to pay and odour, and for ecological awareness on health perception. An interaction-effect was observed for study condition and gender for perceived taste and saltiness, suggesting that women liked the snack better when sustainability information was provided, and men liked it better with no such information. Investigating the impact of carbon footprint information on food choice, in the participating university canteen, the average carbon footprint of all chosen dishes was 1.5 percent lower when carbon footprint information was provided, while there were no significant effects in company canteens, food trucks, and a restaurant. The feedback from customers in the questionnaire was predominantly positive overall. In line with other research, the results have found a lack of knowledge regarding the environmental impact of food production and consumption, particularly among male participants and individuals with lower educational levels. While the documentary appeared to be effective as an educational tool in the short term, no impact was observed after a year. The presentation of the carbon footprint on menus showed inconsistent results regarding the food choices. Since this is not in line with other research findings, the topic should be further investigated in various gastronomic settings and with various ways of presenting the information. As it seems challenging to translate knowledge into action, beliefs, or attitudes, further research should prioritise that aspect. The project found consumers being open to sustainable nutrition, and desiring more information. Sustainability information about reducing food losses processing by-products did not consistently evoke a better hedonic experience in a snack tasting. However, as other studies reported such effects investigating different products and information, further research is needed to explore the effects for various information, such as climate-friendliness of products. In practice, food producers, retailers and caterers, consumers, and policymakers can adopt various strategies to address the challenge of supporting the food system to become more sustainable.
Study protocol to investigate the efficacy of confocal laser endomicroscopy-based selective single-elimination diet over standard fivefold elimination diet in patients with endomicroscopically proven food intolerance: app-assisted, monocentric, double-blind, randomised and controlled trial in Germany
(2023) Heßler, Nicole; Kordowski, Anna; Sasse, Jill; Ahlemann, Greta; Schulz, Franziska; Schröder, Torsten; Exner, Anna; Jablonski, Lennart; Jappe, Uta; Bischoff, Stephan C.; Grzegorzek, Marcin; König, Inke R; Sina, Christian
Introduction: Imprecise nutritional recommendations due to a lack of diagnostic test accuracy are a frequent problem for individuals with adverse reactions to foods but no precise diagnosis. Consequently, patients follow very broad and strict elimination diets to avoid uncontrolled symptoms such as diarrhoea and abdominal pain. Dietary limitations and the uncertainty of developing gastrointestinal symptoms after the inadvertent ingestion of food have been demonstrated to reduce the quality of life (QoL) of affected individuals and subsequently might increase the risk of malnutrition and intestinal dysbiosis. This trial aims to investigate the effects of a tailored diet based on the confocal laser endoscopy (CLE) examination result to limit the side effects of unspecific and broad elimination diets and to increase the patient’s QoL. Methods and analysis: The study is designed as a prospective, double-blind, monocentric, randomised and controlled trial conducted at the University Hospital of Schleswig-Holstein, Campus Lübeck, Germany. One hundred seventy-two patients with non-IgE-related food allergies and positive CLE results will be randomised to either a tailored diet or a standard fivefold elimination diet. The primary endpoints are the difference between the end and the start of the intervention in health-related QoL and the sum score of the severity of symptoms after 12 weeks. Key secondary endpoints are changes in the severity of symptoms, further QoL measurements, self-assessed state of health and number of days with a pathologically altered stool. Microbiome diversity and metabolome of stool, urine and blood will also be investigated. Safety endpoints are body composition, body mass index and adverse events. Ethics and dissemination: The study protocol was accepted by the ethical committee of the University of Lübeck (AZ: 22-111) on 4 May2022. Results of the study will be published in peer-reviewed journals and presented at scientific meetings. Trial registration number: German Clinical Trials Register (DRKS00029323).
NOD1 cooperates with HAX‐1 to promote cell migration in a RIPK2‐ and NF‐ĸB‐independent manner
(2023) Hezinger, Lucy; Bauer, Sarah; Ellwanger, Kornelia; Piotrowsky, Alban; Biber, Felix; Venturelli, Sascha; Kufer, Thomas A.
The human Nod-like receptor protein NOD1 is a well-described pattern-recognition receptor (PRR) with diverse functions. NOD1 associates with F-actin and its protein levels are upregulated in metastatic cancer cells. A hallmark of cancer cells is their ability to migrate, which involves actin remodelling. Using chemotaxis and wound healing assays, we show that NOD1 expression correlated with the migration rate and chemotactic index in the cervical carcinoma cell line HeLa. The effect of NOD1 in cell migration was independent of the downstream kinase RIPK2 and NF-ĸB activity. Additionally, NOD1 negatively regulated the phosphorylation status of cofilin, which inhibits actin turnover. Co-immunoprecipitation assays identified HCLS1-associated protein X-1 (HAX-1) as a previously unknown interaction partner of NOD1. Silencing of HAX-1 expression reduced the migration behaviour to similar levels as NOD1 knockdown, and simultaneous knockdown of NOD1 and HAX-1 showed no additive effect, suggesting that both proteins act in the same pathway. In conclusion, our data revealed an important role of the PRR NOD1 in regulating cell migration as well as chemotaxis in human cervical cancer cells and identified HAX-1 as a protein that interacts with NOD1 and is involved in this signalling pathway.
The role of NLRC5 in obesity
(2024) Bauer, Sarah Katharina; Kufer, Thomas
Obesity and its associated morbidities are major global health problems. It has become evident in the last decades that the state of obesity is intimately linked with our immune system. Pattern recognition receptors (PRRs), the main sensor molecules of the innate immune system, were shown to play an essential role in the pathology of obesity and its associated morbidities. Among others, members of the nucleotide-binding and oligomerization domain (NOD) -like receptors (NLRs), a family of cytosolic PRRs, were associated with the obesity-accompanying low-grade inflammatory response contributing to obesity-associated morbidities. NLRC5 is a NLR protein functioning as key transcriptional regulator of major histocompatibility complex (MHC) class I genes responsible for antigen presentation. Recent observations now suggest novel roles of NLRC5 in metabolic trades, but so far, no confirmation of these singular observations is available, and the underlying mechanisms remain elusive. The aim of this thesis was to characterize the role of the NLR protein NLRC5 in obesity. To this end, two Nlrc5 deficient mouse lines (Nlrc5 deltaExon4-7 and Nlrc5 deltaExon4) were subjected to high-fat diet (HFD) feeding and phenotypic, morphological, and biochemical analyses were performed. Female Nlrc5 deltaExon4-7 mice presented with higher body and adipose tissue (AT) weight gain and larger adipocytes compared to wildtype (WT) animals. This phenotype, however, could not be recapitulated in the Nlrc5 deltaExon4 mouse line. Microbiome analysis revealed subtle alterations of the faecal microbiome by diet:genotype interactions. To further characterize the effect of NLRC5 deficiency on adipocyte differentiation, the CRISPR/Cas9 gene editing system was used to modify Nlrc5 expression in the 3T3-L1 preadipocyte cell line. Using inducible HeLa cell lines with stable GFP-NLRC5 expression we showed NLRC5 to interact with the master regulator of adipogenesis peroxisome proliferator-activated receptor y (PPARy) and to enhance the expression of PPARy target genes. In addition, a contribution of NLRC5 to PPARy’s anti-inflammatory actions was revealed using NLRC5 deficient THP-1 macrophage-like cells and bone marrow-derived macrophages from Nlrc5 deltaExon4-7 mice. To elucidate the mechanism behind the synergy between NLRC5 and PPARy, reporter gene and chromatin immunoprecipitation (ChIP) assays were performed. Lastly, the expression of multiple NLR family members was correlated with body mass index (BMI) in obese human patients and investigated in the adipose tissue and liver of HFD-fed mice, the latter revealing Nlrp10 to be highly upregulated by HFD feeding. Taken together, this thesis provides a comprehensive characterization of Nlrc5 deficient mice on HFD and reveals a function of NLRC5 as transcriptional co-regulator of PPARy targets and its anti-inflammatory properties. In addition, this work provides first insights into the potential mechanism behind the synergistic transcriptional regulation by NLRC5 and PPARy and extends the knowledge on the regulation of NLR expression by HFD feeding.
Die Mikroalge Phaeodactylum tricornutum : Bioverfügbarkeit, Sicherheit und potenzieller gesundheitlicher Nutzen für die humane Ernährung
(2023) Kopp, Lena Janine; Bischoff, Stephan C.
The dissertation by Lena Kopp investigated the suitability of the microalga Phaeodactylum tricornutum (PT) for human nutrition. PT contains essential nutrients such as the long-chain omega-3 fatty acid eicosapentaenoic acid (EPA), which is otherwise found mainly in fish. In addition, PT contains a high content of other nutrients such as proteins, carotenoids (in particular fucoxanthin), vitamins and β-glucans, which have nutritive and therapeutic potential. Clinical and animal studies have shown that the PT biomass ingestion is safe and has potential health effects, such as anti-inflammatory and prebiotic effects. The results suggest that PT can be used as a food for human nutrition with possible health-promoting effects.
Immunomodulatory effects of resveratrol on human intestinal mast cell signaling in vitro and mast cell associated enteritis and colitis in mice
(2023) Bilotta, Sabrina; Lorentz, Axel
By releasing their pre-stored or de novo synthesized mediators, mast cells (MC) are important immunoregulatory cells responsible for a variety of inflammatory reactions. Although known to be major effector cells in immunoglobuline (Ig) E dependent allergic reactions, MC have been widely shown to play a role in various inflammations of the gut. Diseases of the gastrointestinal tract (GIT) are widespread and multicausal. Those affected suffer from the sometimes severe symptoms and may experience restrictions on their daily life. Even if conventional medication is applied routinely, aim of the past and current research is to establish supportive and/or alternative medication that is based on natural substances. These may be on the basis of small natural components like resveratrol, a stilbene mostly found in grapes. Numerous positive properties are attributed to resveratrol. These are anti-inflammatory, anti-cancerogenic, anti-oxidative, as well as neuroprotective effects. The use of substances of natural origin as so-called nutraceuticals can help to increase the acceptance of medication by those affected, but also to reduce and overcome the side effects associated with conventional treatment. Effects of resveratrol were examined on the reactivity of MC isolated from patients’ tissue undergoing bowel resection. The results of this work show that resveratrol exhibited potent inhibitory effects on high affinity IgE receptor mediated activation of MC, strongly inhibiting not only MC degranulation, but also gene expression of the pro-inflammatory cytokines C-X-C motif chemokine ligand (CXCL) 8, C-C motif chemokine ligand (CCL) 2, CCL3, CCL4 and tumor necrosis factor (TNF-) α. Ultimately, the intracellular signaling cascade triggered during MC activation via IgE receptor leads to mediator release. Following IgE receptor mediated activation, phosphorylation of signaling molecules like extracellular signal-regulated kinase (ERK) 1/2 and signal transducer and activator of transcription (STAT) 3, occurs. ERK1/2 was found to be responsible for phosphorylation of mitochondrial STAT3, which contributes significantly to MC degranulation. Treatment with resveratrol was able to inhibit the phosphorylation of STAT3 by more than 50 % and that of ERK1/2 by almost 100 %. Furthermore, the experiments performed succeeded in isolating the mitochondrial fraction from relatively low human intestinal MC (hiMC) numbers. Also, in this fraction we could detect phosphorylation of STAT3 and ERK1/2 after MC activation, which was reduced after treatment with resveratrol. Having shown the strong inhibitory effects in vitro, we set out to examine immunomodulatory effects of resveratrol in vivo. Presence and activity of MC are closely related to intestinal inflammations in consequence of food allergy (FA) and inflammatory bowel disease (IBD). In mice, FA can be studied using the ovalbumin (OVA)-induced allergic enteritis model and colitis can be studied using the IL-10 knockout (-/-) mice, which develop a spontaneous form of chronic colitis. We could show that the oral application of resveratrol inhibited the increase of MC numbers in the colon and duodenum of affected animals in both experimental settings. Less pronounced but still visible effects of resveratrol administration were observed in the colon with regard to epithelial damage, cell infiltration and reduction of goblet cell numbers. In all cases, based on a scoring system, the damage decreased to the level of the corresponding controls receiving no additive and in which no allergic enteritis was induced or nor colitis developed. Overall, allergic enteritis resulted in a weaker symptomatology, and IL-10-/- animals showed a delayed appearance of the typical symptoms. The results of this thesis show a strong inhibitory effect of resveratrol on hiMC. This could be detected for mediator release as well as on gene expression levels and in the phosphorylation of the signaling molecules ERK1/2 and STAT3, which we could also identify in the mitochondria of hiMC. We observed positive influences on MC-associated parameters in the OVA enteritis and IL-10-/- colitis mouse models. With regard to its use as nutraceutical, resveratrol could therefore come more of a focus in the future.
Einfluss der mediterranen Ernährung auf das Fettsäuremuster von Erythrozytenmembranen sowie auf Darmmikrobiota- und Darmbarriere-assoziierte Biomarker : Mechanismen und klinische Anwendungen
(2022) Seethaler, Benjamin; Bischoff, Stephan C.
Dissertation from Benjamin Seethaler: "Effect of the Mediterranean diet on the fatty acid pattern of erythrocyte membranes and on gut microbiota- and gut barrier-associated biomarkers - mechanisms and clinical applications". In summary, the results of the PhD project offer new insights into the biomedical mechanisms of action and health effects of the Mediterranean diet. Of particular importance is the relationship we have shown between dietary fiber from the Mediterranean diet, its fermentation to short-chain fatty acids, and its beneficial influence on impaired intestinal barrier function. In the future, our studies may provide the basis for personalized nutritional therapy to improve impaired gut barrier function in high-risk breast cancer patients. Furthermore, we were able to establish LBP and zonulin as biomarkers to detect gut barrier function and to determine and assess gut barrier disorders. This method validation simplifies or enables the assessment of intestinal barrier function in clinical practice or clinical trials.
Einfluss verschiedener Getreidearten und Herstellungsverfahren auf den Gehalt immunogener Substanzen in Brot sowie in vivo auf die Verträglichkeit an der Maus und im Menschen
(2022) Zimmermann, Julia; Bischoff, Stephan C.
There are three medical conditions that are triggered by consumption of cereals. Celiac disease, wheat allergy and non-celiac wheat sensitivity (NCWS). While the underlying triggers and mechanisms of the first two entities have been extensively studied, there is still uncertainty in this regard for NCWS. Symptoms are nonspecific and diagnostic markers are lacking. Besides bacterial fermentable carbohydrates (FODMAPs), selected cereal proteins such as gluten or α-amylase trypsin inhibitors (ATIs) are in the focus of research as triggers. The aim of the present work was firstly to investigate the influence of the choice of cereal (common wheat, spelt, rye) and the production of bread (degree of milling and choice between yeast and sourdough) on the presence of potentially immunogenic proteins based on proteomic analysis. In a second step, the tolerability of selected breads should be investigated in a transgenic mouse model with intestinal inflammation and in a human study in patients with NCWS and subjective spelt tolerance. This was to narrow down possible triggers of NCWS and to investigate underlying mechanisms. Within the project, protein composition of bread and flour samples was analyzed based on a quantitative proteomics method (nano-UHPLC-ESI-MS based). In addition, a list of known and potentially immunogenic cereal proteins was generated based on Pfam annotation, which was used for the analysis of allergens in flour and bread. This showed that neither the absolute number nor the abundance of these allergenic proteins were dependent on the degree of milling of the flour or the fermentation process of the dough, which means that they are not selectively degraded during bread production. However, such proteins were identified in higher numbers and higher relative amounts in spelt and wheat samples compared to rye samples. Furthermore, different bread types from the proteome analysis were investigated in a mouse model with intestinal inflammation. This did not demonstrate better tolerability of rye bread compared to spelt and wheat bread. Instead, there was a trend for sourdough bread to have less negative effects on intestinal inflammation compared to yeast dough bread. It also turned out that inflammation was increased independently of gluten. No differences were found between wheat and spelt in either the proteomic analysis or the animal studies in this project. However, in a subgroup of NCWS patients, spelt bread is subjectively better tolerated than wheat bread, which could be due to both genetics and the different production of wheat and spelt bread. In order to verify the phenomenon and identify underlying mechanisms, if any, a clinical study was conducted in patients of this subgroup. The aim of the blinded study was to investigate whether spelt bread is actually better tolerated than wheat bread and whether the production process (16h dough or 1h dough + baking agent) has an influence. After each bread (4 days each + 3 days washout), gastrointestinal symptoms were assessed using the Irritable Bowel Syndrome Severity Scoring System (IBS-SSS) questionnaire. Extraintestinal symptoms and various blood and stool parameters were also analyzed. It was found that spelt bread was not better tolerated compared to wheat bread after blinded consumption and that FODMAP-rich bread was not worse tolerated compared to FODMAP-poor bread.

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