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Role of the gut bacterium Akkermansia muciniphila in obesity
Balský, Šimon ; Hrdý, Jiří (advisor) ; Podzimek, Štěpán (referee)
Current scientific knowledge point to a key role of the gut microbiota (GM) in the pathogenesis of various obesity-related diseases. Akkermansia muciniphila (AM), a commensal intestinal bacterium present in the human digestive tract, has become the subject of many research projects. Studies using experimental animal models have shown that AM has significant functional capabilities, including reducing obesity, glucose intolerance, insulin resistance, hepatic steatosis and improved intestinal permeability. It can be assumed that similar effects will also be observed in humans, as already suggested by the first published studies. AM is currently identified as a next generation probiotic due to its ability to positively influence host health. The inclusion of GM modulation in the overall obesity treatment plan, particularly through AM, may significantly increase weight loss efficacy and improve metabolic parameters. This approach may include probiotic/postbiotic, dietary and pharmacological interventions, thereby promoting healthier GM composition and microbiome function in general. This bachelor thesis aims to provide a comprehensive review and analysis of research studies focused on AM in humans in order to gain a deeper understanding of its impact and functions. Based on the analysis of 10...
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Effects of microplastics on earthworm gut microbiome, their immunity system and metabolome
Flohrová, Tereza ; Cajthaml, Tomáš (advisor) ; Lišková, Petra (referee)
Microplastics are widespread pollutants found in aquatic, atmospheric, and soil environments. They are released directly into the soil, for example, from mulch films and textiles. Microplastics accumulate in the soil and can have a negative impact on soil microfauna and macrofauna. Earthworms, acting as ecosystem engineers, and soil and gut bacteria play a significant role in biogeochemical cycles of biogenic elements. Disruption of earthworm function, their gut bacteria, or soil bacteria could have an impact on the entire ecosystem. In the context of this thesis, earthworms of the species Apporectodea sp. were exposed to microplastics from polypropylene black nonwoven textile at concentrations of 1 g/kg soil and 0.0265 g/kg soil for 14, 28, and 56 days. DNA was sequenced to identify bacteria from the earthworm gut, gut contents, and rearing soil. Additionally, untargeted analysis of metabolites from the earthworm body and extraction of immune cells from earthworms using three different methods were conducted. No significant changes caused by the presence of microplastics were found in the representation of bacteria from the gut, gut contents, and soil, but statistically significant changes in the metabolome were detected. A sufficient number of immune cells could not be isolated from the...
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The effect of the gut microbiota in eating disorders
Hlaváčková, Helena ; Roubalová, Radka (advisor) ; Černý, Viktor (referee)
The essential effect of microbiota on human health has been well known for a long time. Commensal microorganisms colonize virtually the entire surface of the human body, but the greatest amount of them can be found in the gut. The gut microbiota plays a crucial role in the digestion of certain food components, synthesis of various substances, or the immune system responses. In the last decade, attention has also been drawn to the mechanisms by which gut microorganisms can influence the human behaviour. One group of diseases, where this phenomenon is being explored, are eating disorders. This is a group of psychiatric disorders characterized by unhealthy eating behaviors. The aim of this thesis is to summarize current knowledge about the mechanisms by which gut microorganisms can interfere with host signaling and regulatory pathways and how these changes relate to the development and course of eating disorders. And from the opposite view, how the patients' behaviour impacts the composition and functioning of the gut microbiota.
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The role of Rorγt+ antigen presenting cells in peripheral tolerance to microbiota
Arutsev, Savva ; Dobeš, Jan (advisor) ; Somova, Veronika (referee)
The intestinal immune system needs mechanisms that provide a balance between suppression and tolerance to microbiota, regulating beneficial and inhibiting pathogenic ones. One such mechanism is based on microbiota-specific Rorγt+ T regulatory cells (Tregs), which can regulate immunity upon recognition of a specific antigen. Rorγt+ antigen-presenting cells (APCs) have been hypothesized to promote microbiota-specific Tregs development, but the specific mechanism was poorly understood until recently. In my bachelor thesis I provide an introduction to Tregs biology, compare and review in detail studies indicating a possible role of lymphoid tissue inducers like group 3 innate lymphoid cells, Janus cells and newly discovered Thetis cells in the generation of Rorγt+ Tregs as well as a possible molecular mechanism based on the integrins Itgav and Itgb8.
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Probiotics and prebiotics in the diet of the population. Effect on disease frequency.
Cherepanova, Ekaterina ; Starnovská, Tamara (advisor) ; Horová, Eva (referee)
Over the past decade, scientific research has focused on the intricate relationship between the human microbiome and the immune system. A particular emphasis in the last three years has been on investigating the impact of the microbiome on the susceptibility and severity of COVID- 19 infections. There is substantial evidence suggesting that the consumption of fermented foods, ranging from fermented vegetables and kefir to yogurt and kimchi, has a beneficial effect on the composition of the intestinal microbiome and, consequently, on the function of the immune system. This study, part of a bachelor's thesis, explores the complex association between regular consumption of fermented foods and the frequency of infectious diseases. Through the analysis of data obtained from a questionnaire, it was found that individuals who regularly incorporated fermented products into their diet exhibited a lower frequency of infectious diseases over the past two years. These results indicate that the consumption of probiotics and prebiotics may positively influence the immune system, reducing the risk of disease. Regarding the examination of the relationship between the consumption of probiotics from food sources and the frequency of COVID-19 infections, a contrasting observation emerged. Those who were fully...
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Host-microbe interactions and its consequences for intestinal inflammation and carcinogenesis
Kejzlarová, Leona ; Kverka, Miloslav (advisor) ; Smrž, Daniel (referee)
A number of physiological and pathological processes, including the transition from chronic inflammation to cancer, are affected by commensal microbes. However, abundance of microbes and ability to produce active metabolites in the intestine depend on environmental factors, particularly diet. Microbes can influence this process in two ways, by producing genotoxic substances that directly damage the epithelium or by stimulating the inflammatory response. The aim of my thesis was to study the interaction among gut microbiota, diet and the immune system with the subsequent influence on the development of colorectal cancer (CRC) in an experimental mouse model. Animals were fed synthetic diets containing either normal amounts of animal protein (17%; KD) or elevated amounts of animal protein (51%; HPD) throughout the experiments. Two weeks after the diets were introduced, intestinal tumors were induced by administering azoxymethane (AOM) and inducing acute inflammation with 2% sodium dextran sulfate one week after AOM injection. At the end of the experiment I evaluated the number of tumors in the colon and the status of the immune response in the intestine, mesenteric lymph nodes and spleen. To study the effect of macrophages, a similar experiment was performed in animals with depleted macrophages using...
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Preparation of food supplement containing probiotic bacteria and components with anti-inflammatory effect
Horňáková, Nikola ; Němcová, Andrea (referee) ; Skoumalová, Petra (advisor)
The presented thesis discusses the issues of chronic inflammatory diseases of the digestive system and suggests the possibility of the alternative natural remedies improving the health conditions or prolonging the remission phase of IBD. The main goal is to design a probiotic supplement enriched by natural anti-inflammatory agents. Phytochemicals, concretely phenolic compounds, flavonoids, and carotenoids suppress harmful inflammatory processes by direct targeting the function of the immune cells or by inhibiting damaging oxidative stress in general. Therefore, there were several plants potentially rich for these biologically active substances selected. Concretely, blueberry (Vaccinium myrtillus), lingonberry (Vaccinium vitis-idaea), turmeric (Curcuma longa), peppermint (Mentha piperita), chamomile (Matricaria recutita), cinnamon (Cinnamomum zeylanicum), ginger (Zingiber officinale) and flax (Linum usitatissimum). The suitable parts of these plants were extracted by using a total of three different solvents – water, ethanol, and hexane for obtaining lipidic extracts. The concentration of total polyphenols, total flavonoids, total carotenoids, and the ascertainment of specific polyphenols was determined in the prepared extracts. These characteristics were enhanced by the measurement of antioxidant activity of the aqueous and ethanolic extracts. The interaction of individual samples with probiotic cultures (Bifidobacterium breve, Lactobacillus acidophilus) and the ability of extracts to influence the viability of probiotics in the model digestion process has been examined. The most interesting samples (aqueous extracts of blueberries, mint, chamomile, and cinnamon) were selected for further experiments. The possible cytotoxicity towards human intestinal epithelial cells was tested in vitro by the MTT tests utilizing the CaCo-2 cell line. Extracts showing the highest levels of beneficial phytochemicals and antioxidant activity, supporting the growth of probiotic cultures, and showing minimal cytotoxic effects on human intestinal cells were then co-encapsulated with probiotics into alginate particles of a diameter of 1 mm. Water extracts of mint, chamomile, and cinnamon have been chosen. The encapsulation efficiency of successfully entrapped probiotics and phenolic compounds was determined in prepared particles. Furthermore, the particles were studied during the process of model digestion, when the release of the desired substances in the various parts of the digestive system was observed and assessed whether the components would reach the crucial point of action – the colon. For the use of the proposed probiotic mixture as a dietary supplement, a recommended dose of 1 g has been determined. Lastly, possible adjustments such as lyophilization or sheathing by an extra protective polymerous layer, e.g. chitosan, were suggested to prolong the shelf life of the particles and volatile substances stability.
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Interspecific and intraspecific variation in gastrointestinal microbiota composition of parrots and its association with incidence of selected disorders
Černá, Kateřina ; Vinkler, Michal (advisor) ; Rychlík, Ivan (referee)
Captive parrots are susceptible to various digestive, metabolic, and behavioural disorders. Recent research in other vertebrates has suggested that these disorders can be linked to the gut microbiota, directly or through the microbiota-gut-brain axis. Although many commercial probiotic products intended for the use in parrots advertise beneficial effects on digestion and mental well- being, these statements are not sufficiently supported with publicly available scientific evidence, but probably rather based on the extrapolation of the knowledge of microbiota-gut-brain interactions in poultry, mice, and humans. However, there are substantial differences in the gastrointestinal tract morphology and gut microbiota composition between parrots and these model vertebrates. This thesis aimed to describe the interspecific and intraspecific variation in the gut microbiota composition of parrots and to link the variation in microbial communities to the incidence of eight selected behavioural and physiological disorders. The gut microbiota composition of 491 individuals from 85 parrot species was analysed using 16S rRNA metabarcoding. The host species, type of feed, and housing environment were identified as the main factors influencing the diversity and composition of the gut microbiota of parrots. A...
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Ecological aspects affecting microbiota in the digestive tracts of birds
Schmiedová, Lucie ; Kreisinger, Jakub (advisor) ; Mrázek, Jakub (referee) ; Gvoždíková Javůrková, Veronika (referee)
The results indicate that songbird GM is dominated by the bacterial phyla Proteobacteria, Firmicutes, Actinobacteria, Tenericutes, Bacteroidetes and Chlamydia, a community that differs from that of mammals. A t the interspecies l evel, GM composition is mainly influenced by phylogeny and less so by sampling site. While ecological factors , and especially diet , are important GM predictors in mammals, the effect of ecological factors , including diet , have a much smaller effect on inte r - and intraspecific variability in songbird GM composition . Our data from barn swallows ( Hirundo rustica ) suggest an effect of social GM transmission among adults forming social pair s, as well as trans - generational transmission from a social mother to her own nestlings. At the same time, we observed differ ing GM in adults and nestlings, with no dramatic change in GM with nestling age, a process previously recognised in mammals. Part of the GM detected appears to remain stable over time , and is therefore su itable for further detailed study. To conclude, our studies demonstrate that s ongbird GM differs from that of mammals and that the factors influencing GM composition appear to differ from those in mammals , thereby highlighting the importance of study ing mu ltiple vertebrate groups (not just mammals ) when...
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The role of nutrition in the prevention of osteoporosis: calcium, proteins and gut microbiota
Holánová, Karolína ; Zikán, Vít (advisor) ; Vágnerová, Tereza (referee)
Introduction: Osteoporosis is defined as a systemic metabolic disease of skeleton. It is characterized by reduced amounts of bone mass and degradation of bone tissue microarchitecture with increased chances of fractures occurring. Women after menopause are affected by lack of estrogen and therefore have increased risk of osteoporosis. Goal: The goal of the diploma thesis is to evaluate the nutritional state of women after menopause with osteoporosis (With OP) and without osteoporosis (Without OP) focusing on calcium, proteins and nutrients which are affecting gut microbiota (prebiotics and probiotics). Methods: Nutritional state was evaluated based on three-day diet analysis and questionnaire about dietary preferences. Amounts of particular nutrients in respondents diets were obtained by using web page www.kaloricketabulky.cz. Bone material densities were measured by dual energy X-ray absorptiometry (DXA). Results: Nutritional breakdown of diets did not show any statistically significant differences in most of the cases. The only exception was protein and fiber intake, where the group without OP reported higher intake. Both sets of respondents reported higher intake of calories, fats and proteins then recommended. On the other hand, low intake of carbs, fiber, calcium and probiotics was discovered...
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