Cytokine elevation in the mouse small intestine at the early stage ofinfection with the gastrointestinal parasite Heligmosomoidespolygyrus

摘要

To eliminate pathogens, the initiation of an appropriate immune response is critical.When the gastrointestinal nematode, Heligmosomoides polygyrus (Hp),invades the small intestine, a type-2 cytokine response is initiated; however, thisresponse is not sufficient to clear the infection, and chronic infection can ensue. Inthis study, the host defense against Hp was investigated in mice with a focus on the roleof CD4+ T cells. To this end, tissues from the small intestine and mesenteric lymph node(MLN) were collected every day from just after infection until Day 5 because many previousstudies have described the later stages of infection from Day 8 to Day 12, during which Hpreturns to the lumen and Th2 cytokine expression reaches its peak. In this study, wefocused on investigating the initiation of the type-2 immune response. Our resultsindicated that the larvae encysted by Day 3. Increased type-2 cytokine gene expressionstarted in the small intestine before Day 2 and increased again on Day 5. Interferon (IFN)γ increased significantly on the second day. Flow cytometry and gene expression analysisof MLN cells revealed that CD4+ T cells were not activated until Day 4. These resultssuggested that innate immune cells in submucosa are activated immediately after infection,but CD4+ T cells accumulate in the cyst zone later. In addition, IFNγ may have animportant role in converting type-2 cytokine-producing cells from innate cells to CD4+ Tcells.