Interactions between Campylobacter jejuni and the host

by Szymanski, Christine Mary

Campylobactersare a common cause of diarrbea worldwide. Cmpyfobacter jejmi accounts for approximately 95% of Campybbacter infections. In addition to causing diarrhea, C. jejuni bas also ben reported to cause extra-intestinal complications such as Guillain-Barré syndrome (GBS), reactive arthritis, Reiter' s syndrome, meningitis, abortions, c holecy stitis, bacterernia and urinary tract infections. Although C. jejuni is recognized as an important pathogen, very IittIe is known about how the organism causes disease. In this study 1 investigated severai mechanisms by which C. jejuni may cause disease. 1found that the swllnming behavior of C. jemi in a viscous environment may be an important factor in the interaction of these organisms with host epithelial cells. The pH, which affects C. jejuni motility, may also infiuence the tropism of these organisms. Motility plays several key roles in C. jejuni pathogenesis, including increasing the efficiency of C. jejuni attachment to host epithelial cells. Oligosaccharide sequences probably play a subordinate role in C. jejuni attachent to eukaryotic cells. However, C. jejuni binds to lipids and may interact with üpids in host ceil membranes or in the intestinal mucosa. However, lipids only partially inhibiteci C.jejuni binding to Chinese hamster ovary cells suggesting that multiple interactions occur between the bactena and host cells. C. jejwii membrane proteins of 14 and 55 kDa bound to phosphatidylethanolamine. Experiments also demonstrated lipid hydrolysing activity: both phospholipase C and lipase activities in C. jejmi membrane preparations and acyl hydrolase and phospholipase C activities in C. jejmi ceil extracts (cytoplasm andlor periplasm). Another C. jejuni 14 kDa protein demonstrated 62.8% sequence homology to the lipase chaperone proteins of Pseudomonas species. Antibodies against two known Pseudomonus lipase chaperones cross-reacted with the C.jejuni 14 kDa protein. C.jejuni possesses at least two 14 D a proteins one of which binds phosphatidyiethanoIarnine resulting in tipid hydro lysis or transport, and the other which may function as a lipase chaperone. AU GBS patient sera exarnined contained antibodies to a C. jejuni L4 kDa protein. Also. the fatty acid binding protein, myelin P2,may share some homology with a C.jejuni 14 kDa protein. Further studies are necessary to determine whether C.jejuni expresses a fatty acid binding protein analog and whether the C-jejuni 14 kDa protein plays a de in the induction of GBS. C. jejuni invades Cam-2 ceils through a mimfi1ament and microtubuledependent mechanism. Funher studies are necessary in order to determine if calcium signalhg is involved in pathogenesis.