The sialylated lipooligosaccharide outer core in Campylobacter jejuni is an important determinant for epithelial cell invasion.
Campylobacter jejuni is a frequent cause of bacterial gastroenteritis worldwide. Lipooligosaccharide (LOS) has been identified as an important virulence factor that may play a role in microbial adhesion and invasion. Here we specifically address the question of whether LOS sialylation affects the interaction of C. jejuni with human epithelial cells. For this purpose, 14 strains associated with Guillain-Barré syndrome (GBS), 34 enteritis-associated strains, the 81-176 reference strain, and 6 Penner serotype strains were tested for invasion of two epithelial cell lines. C. jejuni strains expressing sialylated LOS (classes A, B, and C) invaded cells significantly more frequently than strains expressing nonsialylated LOS (classes D and E) (P < 0.0001). To further explore this observation, we inactivated the LOS sialyltransferase (Cst-II) via knockout mutagenesis in three GBS-associated C. jejuni strains expressing sialylated LOS (GB2, GB11, and GB19). All knockout strains displayed significantly lower levels of invasion than the respective wild types. Complementation of a Deltacst-II mutant strain restored LOS sialylation and reset the invasiveness to wild-type levels. Finally, formalin-fixed wild-type strains GB2, GB11 and GB19, but not the isogenic Deltacst-II mutants that lack sialic acid, were able to inhibit epithelial invasion by viable GB2, GB11, and GB19 strains. We conclude that sialylation of the LOS outer core contributes significantly to epithelial invasion by C. jejuni and may thus play a role in subsequent postinfectious pathologies.
Louwen
Rogier
R
Department of Medical Microbiology and Infectious Diseases, Erasmus MC, University Medical Center Rotterdam, Rotterdam, The Netherlands. r.louwen@erasmusmc.nl
Heikema
Astrid
A
van Belkum
Alex
A
Ott
Alewijn
A
Gilbert
Michel
M
Ang
Wim
W
Endtz
Hubert P
HP
Bergman
Mathijs P
MP
Nieuwenhuis
Edward E
EE
D001426:Bacterial Proteins / Q000235:genetics; D016123:Campylobacter jejuni / Q000737:chemistry* / Q000235:genetics / Q000472:pathogenicity*; D002240:Carbohydrate Sequence; D002460:Cell Line; D015169:Colony Count, Microbial; D003600:Cytosol / Q000382:microbiology; D004847:Epithelial Cells / Q000382:microbiology*; D017353:Gene Deletion; D005816:Genetic Complementation Test; D006801:Humans; D008070:Lipopolysaccharides / Q000378:metabolism*; D008969:Molecular Sequence Data; D016254:Mutagenesis, Insertional; D012799:Sialyltransferases / Q000235:genetics; D037521:Virulence Factors / Q000378:metabolism*
D001426:Bacterial Proteins; D008070:Lipopolysaccharides; D037521:Virulence Factors; C023023:lipid-linked oligosaccharides; D012799:Sialyltransferases; C043662:alpha-N-acetylneuraminate alpha-2,8-sialyltransferase