Veza između debljine i bakterija

undergraduate thesis

• Title (english): Obesity related to bacteria
• Author: Martina Šerić
• Mentor: Ivana Ivančić Baće (mentor)
• Granter: University of Zagreb; Faculty of Science; (Department of Biology); Zagreb
• Defense date and country: 2012, Croatia
• Scientific / art field, discipline and subdiscipline: NATURAL SCIENCES; Biology

Abstract

Metabolički sindrom je niz povezanih poremećaja koji dovode do razvoja dijabetesa i kardiovaskularnih bolesti. Usko je povezan s pretilošću, smanjenom fizičkom aktivnošću i inzulinskom rezistencijom. U zadnje vrijeme smatra se da crijevne bakterije pridonose razvoju pretilosti i ostalim aspektima metaboličkog sindroma. U debelom crijevu čovjeka nalazi se mnoštvo različitih bakterija koje sudjeluju u sintezi esencijalnih aminokiselina i vitamina, te razgrađuju različite polisaharide koji su nama neprobavljivi. Među ljudima postoje razlike u sastavu crijevnih bakterija. Prema dominantnim rodovima izdvojena su 3 enterotipa: Bacteroides, Prevotella i Ruminococcus. Istraživanja provedena na miševima i ljudima pokazala su da se crijevne bakterijske zajednice pretilih i mršavih pojedinaca razlikuju u zastupljenosti bakterijskih koljena Firmicutes i Bacteroidetes. Kod pretilih pojedinaca smanjena je raznolikost vrsta crijevnih bakterija. U njih dominira koljeno Firmicutes, ali sa smanjenjem tjelesne mase povećava se zastupljenost koljena Bacteroidetes. Genotip domaćina utječe na sastav crijevnih bakterija, a njihova efikasnost u ekstrahiranju energije iz hrane utječe na predispoziciju za razvoj pretilosti. Drugačiji pristup problemu naglašava ulogu interakcije urođenog imunološkog sustava sa crijevnim bakterijama u razvoju pretilosti. Gubitak TLR5 receptora koji se nalazi na stanicama urođene imunosti i prepoznaje bakterijski flagelin, u miševa uzrokuje promjene u sastavu crijevnih bakterija. To dovodi do stanja blage upale (povećava se količina proupalnih citokina u masnom tkivu) i smanjuje osjetljivost inzulinskih receptora. Rezultat je prekomjerni apetit što potiče pojavu ostalih simptoma metaboličkog sindroma. Pretilost je izravna posljedica prekomjernog unosa energije u odnosu na potrošnju. Međutim, istraživanja ukazuju da interakcija između domaćina i njegovih crijevnih bakterija ipak može utjecati na razvoj metaboličkog sindroma.

Abstract (english)

Metabolic syndrome is a group of related disorders that lead to the development of diabetes and cardiovascular disease. It is related to obesity, physical inactivity and insulin resistance. Lately, it is considered that gut bacteria contribute to development of obesity and other aspects of metabolic syndrome. There are numerous bacteria in human distal gut that synthesize essential amino acids and vitamins, and contribute to degradation of otherwise indigestible polysaccharides. Composition of gut bacteria differs between humans. They are divided into three enterotypes named after the dominant genus: Bacteroides, Prevotella and Ruminococcus. Studies on mice and humans have shown that there are differences in abundance of Firmicutes and Bacteroidetes between gut bacteria of obese and lean individuals. Obese individuals have less diverse gut bacterial species. They have more Firmicutes, but as they lose weight, abundance of Bacteroidetes increases. Host genotype affects gut bacterial composition, and their efficiency of extracting energy from food contributes to development of obesity. A different approach emphasizes the role of interaction between innate immune system and gut bacteria in development of obesity. Loss of TLR5, a receptor found on innate imunnity cells that recognizes bacterial flagellin, causes change of gut bacterial composition in mice. That leads to low-grade inflammation (the amount of proinflammatory cytokines in adipose tissue increases) and insulin receptor desensitization. That results in hyperphagia, which contributes to development of other metabolic syndrome symptoms. Obesity is directly caused by surplus of energy consumption over expenditure. However, studies show that interaction between host and his gut bacteria can affect the development of metabolic syndrome.

• Keywords: pretilost; bakterije
• Keywords (english): obesity; bacteria
• Language: croatian
• URN:NBN: urn:nbn:hr:217:182644
• Study programme: Title: Molecular Biology; Study programme type: university; Study level: undergraduate; Academic / professional title: sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije (sveučilišni/a prvostupnik/prvostupnica (baccalaureus/baccalaurea) molekularne biologije)
• Type of resource: Text
• File origin: Born digital
• Access conditions: Open access
• Created on: 2018-04-18 12:53:12