Publikationsdatenbank

Identification and characterisation of Campylobacter jejuni novel virulence factors and mucin-associated regulatory factors relevant to the infection process (2021)

Art

Hochschulschrift

Autor

Xi, De (WE 8)

Quelle

Berlin: Mensch & Buch Verlag, 2021 — XII, 85 Seiten

Sprache

Englisch

Verweise

URL (Volltext): https://refubium.fu-berlin.de/handle/fub188/32785

Kontakt

Institut für Lebensmittelsicherheit und -hygiene

Königsweg 69
14163 Berlin
+49 30 838 62551 / 52790
lebensmittelhygiene@vetmed.fu-berlin.de / fleischhygiene@vetmed.fu-berlin.de

Abstract / Zusammenfassung

C. jejuni is an important zoonotic pathogen causing enterocolitis in humans worldwide. Multiple factors including motility, adhesion, invasion, intracellular survival and subversion of host cell responses together constitute the virulence machinery of C. jejuni. Among them, adhesion and invasion are thought to be the essential features for pathogenesis of C. jejuni. To establish an infection, C. jejuni have to bypass the physical and immunological barriers of the gastrointestinal tract. The mucus layer of the gastrointestinal tract epithelium serves as the first line of host defence. However, C. jejuni have evolved several traits to subvert or avoid this barrier and directly access the intestinal epithelium. Therefore, the interaction of C. jejuni and mucus is recognised as a critical process in the colonisation of mucosal surfaces. Herein, the specific binding between bacteria and host via “glycan-glycan talk” constitutes a prominent mechanism for bacteria to mediate adhesion and invasion of host cells. During infection, mucin regulation and posttranscriptional modification are mediated by multitude of factors, in which the regulatory miRNA networks play a prominent role. To identify further virulence associated genes, 24 transposon insertion mutants were screened for the ability to enter cultured epithelial cells HT-29/B6 using the established invasion assay. Two mutants with altered capability to invade human intestinal epithelial cells have been selected and used for further phenotypical characterisation. Moreover, the well-established in vivo murine infection model and in vitro human cells infection model were used to study host mucin responses to C. jejuni infection as well as to identify the potential regulatory network concerted by miRNAs in this context. The results indicated that genes regulated by Cj1507c have an impact on efficient adhesion, invasion and intracellular survival of C. jejuni in HT-29/B6 cells. Genes regulated by Cj1492c lead to restricted attachment and hence internalisation of C. jejuni. Also, signal sensing by Cj1492c impacts the intracellular survival capacities. Moreover, C. jejuni infection cause dysregulation of mucin MUC2 and its mediator TFF3 as well as the mucin-associated miRNAs at transcriptional level. C. jejuni infection also induced altered gene expression of the glycosyltransferases ST3GAL1 and ST3GAL2 involved in mucin type O-glycan biosynthesis. These mucin-associated factors were found to interact in a coordinated manner concerted by a miRNA-dependent regulatory network during C. jejuni infection. Additional RNAi and luciferase reporter assay provide evidence that the regulatory relationship of miR-615-3p and ST3GAL2 was involved in the host cellular response to C. jejuni infection.