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

Summary

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.

Abstract

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.

Protocol

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 side of the mouse and wet the abdomen with 70% ethanol.
4. Using forceps grasp the abdominal skin and make a small incision using scissors. Cut the sk....

Discussion

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.......

Materials

List of materials used in this article

Name	Company	Catalog Number	Comments
Animal Feeding Needles (18 x 1½")	Popper & Sons, Inc.	7912
Smooth curved Forceps	Roboz Surgical Instruments Co.	RS-5047
DMEM	GIBCO, by Life Technologies	11965
NOD.Cg-Prkdcscid Il2rgtm1Wjl/SzJ (NSG)	Jackson Laboratory	005557	These are the mice we used, however, any immunodeficient mice or susceptible strain should work.
RNAlater	Qiagen	76104
2 ml tubes	Axygen Scientific	MCT-200-C
15 ml tubes	Falcon BD	352096
6 well plates	Falcon BD	353046
Paraformaldehyde	Electron Microscopy Sciences	15710
α-RELMβ antibody	PeproTech Inc	0694270Rb