Odziv imunskega sistema na izbrane seve bakterije Escherichia coli in vpliv na cirkadiano uro

Žužek, Zala (author), Starčič Erjavec, Marjanca (mentor), Kovač, Urša (comentor)

Osrednja cirkadiana ura, locirana v možganih, sinhronizira periferne cirkadiane ure v organih, tkivih in celicah ter z vplivom na mnogo metabolnih, fizioloških in vedenjskih procesov organizmu pomaga ohranjati homeostazo. Pri vzpostavljanju homeostaze gostitelja ima pomembno vlogo tudi črevesna mikrobiota. Dobro poznan je vpliv mikrobiote na imunski sistem, nedavne raziskave pa disbiozo povezujejo tudi z motnjami cirkadiane ure gostitelja. V magistrski nalogi smo se osredotočili na pomembnega predstavnika mikrobiote, bakterijo Escherichia coli (E. coli), in preiskovali njen vpliv na evkariontsko cirkadiano uro in imunski sistem v vzpostavljeni stabilni kokulturi s človeško jetrno celično linijo HepG2. Za poskuse smo iz zbirke sevov E. coli, pridobljenih iz vzorcev blata zdravih posameznikov, izbrali dva predstavnika te bakterijske vrste, sev BJ23 s številnimi, in sev BJ17 z le nekaj zapisi za z virulenco povezane dejavnike. Po 4 urni inkubaciji seva BJ v kokulturi s celično linijo HepG2 smo izpostavljene celice HepG2 vzorčili 72 ur in analizirali količino relativne mRNA cirkadianih ter imunskih genov z metodo qPCR. Ugotovili smo, da bakterijski sev BJ23 po 72-ih urah močneje vpliva na gene cirkadiane ure celic HepG2, medtem ko pri aktivaciji genov imunskega sistema zaradi nizkega izražanja mRNA testiranih imunskih genov med sevoma ni bilo opaznih razlik. Naša raziskava je tako pripomogla k boljšemu razumevanju vpliva bakterije E. coli na cirkadiano uro gostitelja.

• Language: Slovenian
• Keywords: cirkadiana ura, cirkadiani ritem, cirkadiani geni, črevesna mikrobiota, Escherichia coli, virulentni dejavniki, imunski sistem, citokini
• Work type: Master's thesis/paper
• Typology: 2.09 - Master's Thesis
• Organization: BF - Biotechnical Faculty
• Publisher: [Z. Žužek]
• Year: 2020
• PID: 20.500.12556/RUL-118082
• UDC: 577.21:616-097
• COBISS.SI-ID: 25660931
• Publication date in RUL: 19.08.2020

ŽUŽEK, Zala, 2020, Odziv imunskega sistema na izbrane seve bakterije Escherichia coli in vpliv na cirkadiano uro [online]. Master’s thesis. Z. Žužek. [Accessed 29 June 2025]. Retrieved from: https://repozitorij.uni-lj.si/IzpisGradiva.php?lang=eng&id=118082

Secondary language

• Language: English
• Title: Response of immune system to selected Escherichia coli strains and impact on the circadian clock

Abstract

Central circadian clock, located in the brain, synchronizes peripheral clocks found in almost every cell of the body and with its effect on metabolism, physiology and behavior of the organism maintains homeostasis. An important factor, when it comes to establishing homeostasis in the host, is also the intestinal microbiota. It is well known that microbiota and host immune system are tightly connected, the latest research showed that dysbiosis results in altered circadian clock. In our study we focused on the bacteria Escherichia coli (E. coli) as an important representative of microbiota and investigated its effect on the host circadian rhythms and immune system in the established stable coculture with human liver cells HepG2. For the assays two different E. coli strains from the collection of fecal E. coli strains from healthy individuals were selected: the strain BJ23 with many and strain BJ17 with only a few genes encoding virulence associated factors. After a 4 hour incubation of the BJ strain with the HepG2 cell line, the exposed HepG2 cells were sampled for 72 hours and the relative quantity of mRNA of the circadian and immune genes was analyzed with qPCR. We found that after 72 hours the bacterial strain BJ23 had a greater impact on the circadian clock genes of HepG2 cells, while there was no difference in activation of immune system genes between both employed strains. Our research therefore contributed to a better understanding of the E. coli impact on the host’s circadian clock.

• Keywords: circadian clock, circadian rhythms, circadian genes, intestinal microbiota, Escherichia coli, virulence factors, immune response, cytokines