Virulence genes and cytokine profile in systemic murine Campylobacter coli infection

Campylobacter coli are one of the most common bacteria in bacterial gastroenteritis and acute enterocolitis in humans. However, relatively little is known regarding the mechanisms of pathogenesis and host response to C. coli infections. To investigate the influence of genetic changes, we first used PCR to demonstrate the presence of the known virulence genes cadF, virB11, cdtB, cdtC and ceuE in the clinical isolate C. coli 26536, which was isolated from the liver of infected BALB/c mice. Sequence analyses of the cadF, virB11, cdtB and ceuE genes in C. coli 26536 confirmed the stability in these virulence genes during their transmission through the host. We further investigated C. coli infection for the bacterial clearance from the liver and spleen of infected mice, and for their immune response. C. coli persisted well in both organs, with better survival in the liver. We also determined the levels of several pro-inflammatory cytokines (i.e., interleukin [IL]-6, IL-12, interferon-γ, tumor necrosis factor-α) and the anti-inflammatory cytokine IL-10 in plasma and in liver homogenates from the infected mice, using enzyme-linked immunosorbent assays. The lowest levels among these cytokines were for tumor necrosis factor-α in the plasma and IL-6 in the liver on days 1, 3 and 8 post-infection. The most pronounced production was for IL-10, in both plasma (days 1 and 8 post-infection) and liver (day 8 post-infection), which suggests that it has a role in healing of the organ inflammation. Our findings showed dynamic relationships between pro- and anti-inflammatory cytokines and thus contribute toward clarification of the healing processes involved in the resolution of C. coli infections.