CXCL8 and infection: RNA-seq of HIOs infected with S. Typhimurium for 3 hours showed differential regulation of several genes involved in cytokine signaling, extracellular matrix reorganization and innate immune responses.26 Gene expression studies showed that proinflammatory cytokines such as IL-23, IL-1β, IL-8, CXCL2 and TNFα were upregulated upon infection with S. Typhimurium.