TLR4 and infection: Similarly, infection of human biliary epithelial cells (cholangiocytes) with C. parvum induced recruitment of TLR2 and TLR4 to the attachment site of infected epithelial cells [89] and infection of the human epithelial cell line HCT-8 with C. parvum has also been shown to induce the expression of the pro-inflammatory cytokine IL-18 [90].