Trichuris muris Infection: A Model of Type 2 Immunity and Inflammation in the Gut

Trichuris muris infection is an intestinal model of Th2 immunity where resistant mice generate a protective Th2 response and susceptible mice generate a pathological Th1 response.

Trichuris muris is a natural pathogen of mice and is biologically and antigenically similar to species of Trichuris that infect humans and livestock¹. Infective eggs are given by oral gavage, hatch in the distal small intestine, invade the intestinal epithelial cells (IECs) that line the crypts of the cecum and proximal colon and upon maturation the worms release eggs into the environment¹. This model is a powerful tool to examine factors that control CD4⁺ T helper (Th) cell activation as well as changes in the intestinal epithelium. The immune response that occurs in resistant inbred strains, such as C57BL/6 and BALB/c, is characterized by Th2 polarized cytokines (IL-4, IL-5 and IL-13) and expulsion of worms while Th1-associated cytokines (IL-12, IL-18, IFN-γ) promote chronic infections in genetically susceptible AKR/J mice^2-6. Th2 cytokines promote physiological changes in the intestinal microenvironment including rapid turnover of IECs, goblet cell differentiation, recruitment and changes in epithelial permeability and smooth muscle contraction, all of which have been implicated in worm expulsion^7-15. Here we detail a protocol for propagating Trichuris muris eggs which can be used in subsequent experiments. We also provide a sample experimental harvest with suggestions for post-infection analysis. Overall, this protocol will provide researchers with the basic tools to perform a Trichuris muris mouse infection model which can be used to address questions pertaining to Th proclivity in the gastrointestinal tract as well as immune effector functions of IECs.

1. Propagating Trichuris muris eggs

1. To generate new batches of Trichuris muris eggs, infect 20-30 immunodeficient mice (eg. NOD.Cg-Prkdc^scidIl2rg^tm1Wjl/SzJ (NSG) or 129S6/SvEvTac-Rag2^tm1Fwa (RAG2^-/-)) or genetically susceptible mice (eg. AKR/J) that are 6-8 weeks old with approximately 300 Trichuris muris eggs by oral gavage.
2. After 32–35 days sacrifice the mice by CO₂ asphyxiation.
3. Expose the ventral .......

This protocol details a standard high dose acute Trichuris muris infection which can be modified as required by the investigator. For example, mice can be sacrificed and tissues harvested on different days. To determine that the mice have successfully established full worm burden they can be sacrificed on day 14, at which point all mice should carry a burden of approximately 200 worms. Mice can also be infected for 32 days where any worm detected will have reached maturity and would remain with host for the d.......

This work was supported by the Canadian Institutes of Health Research (MSH-95368, MOP-89773 and MOP-106623 to C.Z.) and the Canada Foundation for Innovation. S.C.M. is the recipient of a CIHR/Canadian Association of Gastroenterology postdoctoral fellowship. C.Z. is a CIHR New Investigator.