TNF and infection: Our in vitro [22,44] and in vivo [15] studies observed that increased defensin expression in Salmonella-infected IECs and mice with Salmonella colitis using active vitamin D protected the host against infection, while downregulating proinflammatory responses (IL-6, IL-8, TNF-α, and IL-1β) protected the host from the detrimental effects of overwhelming inflammation, via vitamin D receptor (VDR).