CXCL8 and escherichia coli infection: Strikingly, the accumulation of interleukin-8, a proinflammatory cytokine involved in innate immunity, is impaired by high c-di-GMP levels upon Salmonella enterica serovar Typhimurium infection of HAT-29 cells (67) and is flagellin triggered in intestinal epithelial cells upon enteroaggregative Escherichia coli infection (68).