HIC1 links retinoic acid signalling to group 3 innate lymphoid cell-dependent regulation of intestinal immunity and homeostasis.

The intestinal immune system must be able to respond to a wide variety of infectious organisms while maintaining tolerance to non-pathogenic microbes and food antigens. The Vitamin A metabolite all-trans-retinoic acid (atRA) has been implicated in the regulation of this balance, partially by regulating innate lymphoid cell (ILC) responses in the intestine. However, the molecular mechanisms of atRA-dependent intestinal immunity and homeostasis remain elusive. Here we define a role for the transcriptional repressor Hypermethylated in cancer 1 (HIC1, ZBTB29) in the regulation of ILC responses in the intestine. Intestinal ILCs express HIC1 in a vitamin A-dependent manner. In the absence of HIC1, group 3 ILCs (ILC3s) that produce IL-22 are lost, resulting in increased susceptibility to infection with the bacterial pathogen Citrobacter rodentium. Thus, atRA-dependent expression of HIC1 in ILC3s regulates intestinal homeostasis and protective immunity.

Early-life antibiotic treatment enhances the pathogenicity of CD4+ T cells during intestinal inflammation.

The incidence of inflammatory bowel diseases (IBDs) has steadily increased in recent decades-a phenomenon that cannot be explained by genetic mutations alone. Other factors, including the composition of the intestinal microbiome, are potentially important contributors to the increased occurrence of this group of diseases. Previous reports have shown a correlation between early-life antibiotic (Abx) treatment and an increased incidence of IBD. In this report, we investigated the effects of early-life Abx treatments on the pathogenicity of CD4+ T cells using an experimental T cell transfer model of IBD. Our results show that CD4+ T cells isolated from adult mice that had been treated with Abx during gestation and in early life induced a faster onset of IBD in Rag1-deficient mice compared with CD4+ T cells of untreated mice. Ex vivo functional analyses of IBD-inducing CD4+ T cells did not show significant differences in their immunologic potential ex vivo, despite their in vivo phenotype. However, genome-wide gene-expression analysis revealed that these cells displayed dysregulated expression of genes associated with cell-cycle regulation, metabolism, and cellular stress. Analysis of Abx-treated CD4+ T cell donors showed systemically elevated levels of the stress hormone corticosterone throughout life compared with untreated donors. The cohousing of Abx-treated mice with untreated mice decreased serum corticosterone, and a consequent transfer of the cells from cohoused mice into Rag1-deficient mice restored the onset and severity of disease to that of untreated animals. Thus, our results suggest that early-life Abx treatment results in a stress response with high levels of corticosterone that influences CD4+ T cell function.

Intestinal Epithelial Cell-Intrinsic Deletion of Setd7 Identifies Role for Developmental Pathways in Immunity to Helminth Infection.

The intestine is a common site for a variety of pathogenic infections. Helminth infections continue to be major causes of disease worldwide, and are a significant burden on health care systems. Lysine methyltransferases are part of a family of novel attractive targets for drug discovery. SETD7 is a member of the Suppressor of variegation 3-9-Enhancer of zeste-Trithorax (SET) domain-containing family of lysine methyltransferases, and has been shown to methylate and alter the function of a wide variety of proteins in vitro. A few of these putative methylation targets have been shown to be important in resistance against pathogens. We therefore sought to study the role of SETD7 during parasitic infections. We find that Setd7-/- mice display increased resistance to infection with the helminth Trichuris muris but not Heligmosomoides polygyrus bakeri. Resistance to T. muris relies on an appropriate type 2 immune response that in turn prompts intestinal epithelial cells (IECs) to alter differentiation and proliferation kinetics. Here we show that SETD7 does not affect immune cell responses during infection. Instead, we found that IEC-specific deletion of Setd7 renders mice resistant to T. muris by controlling IEC turnover, an important aspect of anti-helminth immune responses. We further show that SETD7 controls IEC turnover by modulating developmental signaling pathways such as Hippo/YAP and Wnt/ß-Catenin. We show that the Hippo pathway specifically is relevant during T. muris infection as verteporfin (a YAP inhibitor) treated mice became susceptible to T. muris. We conclude that SETD7 plays an important role in IEC biology during infection.

Chronic Trichuris muris infection alters hematopoiesis and causes IFN-γ-expressing T-cell accumulation in the mouse bone marrow.

Proinflammatory cytokines produced during immune responses to infectious stimuli are well-characterized to have secondary effects on the function of hematopoietic progenitor cells in the BM. However, these effects on the BM are poorly characterized during chronic infection with intestinal helminth parasites. In this study, we use the Trichuris muris model of infection and show that Th1 cell-associated, but not acute Th2 cell-associated, responses to chronic T. muris infection cause a major, transient expansion of CD48- CD150- multipotent progenitor cells in the BM that is dependent on the presence of adaptive immune cells and IFN-γ signaling. Chronic T. muris infection also broadly stimulated proliferation of BM progenitor cells including CD48- CD150+ hematopoietic stem cells. This shift in progenitor activity during chronic T. muris infection correlated with a functional increase in myeloid colony formation in vitro as well as neutrophilia in the BM and peripheral blood. In parallel, we observed an accumulation of CD4+ , CD8+ , and CD4- CD8- (double negative) T cells that expressed IFN-γ, displaying activated and central memory-type phenotypes in the bone marrow during chronic infection. Thus, these results demonstrate that Th1 cell-driven responses in the intestine during chronic helminth infection potently influence upstream hematopoietic processes in the BM via IFN-γ.

G9a regulates group 2 innate lymphoid cell development by repressing the group 3 innate lymphoid cell program.

Innate lymphoid cells (ILCs) are emerging as important regulators of homeostatic and disease-associated immune processes. Despite recent advances in defining the molecular pathways that control development and function of ILCs, the epigenetic mechanisms that regulate ILC biology are unknown. Here, we identify a role for the lysine methyltransferase G9a in regulating ILC2 development and function. Mice with a hematopoietic cell-specific deletion of G9a (Vav.G9a(-/-) mice) have a severe reduction in ILC2s in peripheral sites, associated with impaired development of immature ILC2s in the bone marrow. Accordingly, Vav.G9a(-/-) mice are resistant to the development of allergic lung inflammation. G9a-dependent dimethylation of histone 3 lysine 9 (H3K9me2) is a repressive histone mark that is associated with gene silencing. Genome-wide expression analysis demonstrated that the absence of G9a led to increased expression of ILC3-associated genes in developing ILC2 populations. Further, we found high levels of G9a-dependent H3K9me2 at ILC3-specific genetic loci, demonstrating that G9a-mediated repression of ILC3-associated genes is critical for the optimal development of ILC2s. Together, these results provide the first identification of an epigenetic regulatory mechanism in ILC development and function.

SETD7 Controls Intestinal Regeneration and Tumorigenesis by Regulating Wnt/ß-Catenin and Hippo/YAP Signaling.

Intestinal tumorigenesis is a result of mutations in signaling pathways that control cellular proliferation, differentiation, and survival. Mutations in the Wnt/ß-catenin pathway are associated with the majority of intestinal cancers, while dysregulation of the Hippo/Yes-Associated Protein (YAP) pathway is an emerging regulator of intestinal tumorigenesis. In addition, these closely related pathways play a central role during intestinal regeneration. We have previously shown that methylation of the Hippo transducer YAP by the lysine methyltransferase SETD7 controls its subcellular localization and function. We now show that SETD7 is required for Wnt-driven intestinal tumorigenesis and regeneration. Mechanistically, SETD7 is part of a complex containing YAP, AXIN1, and ß-catenin, and SETD7-dependent methylation of YAP facilitates Wnt-induced nuclear accumulation of ß-catenin. Collectively, these results define a methyltransferase-dependent regulatory mechanism that links the Wnt/ß-catenin and Hippo/YAP pathways during intestinal regeneration and tumorigenesis.

Dendritic-cell expression of Ship1 regulates Th2 immunity to helminth infection in mice.

In mouse models of infection with the gastrointestinal parasite Trichuris muris, appropriate dendritic-cell (DC) Ag sampling, migration, and presentation to T cells are necessary to mount a protective Th2-polarized adaptive immune response, which is needed to clear infection. SH2-containing inositol 5'-phosphatase 1 (SHIP-1) has been shown to be an important regulator of DC function in vitro through the negative regulation of the phosphoinositide 3-kinase (PI3K) pathway, but its role in vivo is relatively unexplored. In the current work, mice with a specific deletion of SHIP-1 in DCs (Ship1(ΔDC) ) were infected with the parasite T. muris. Ship1(ΔDC) mice were susceptible to infection due to ineffective priming of Th2-polarized responses. This is likely due to an increased production of interleukin (IL) 12p40 by SHIP-1-deficient DCs, as in vivo antibody blockade of IL-12p40 was able to facilitate the clearing of infection in Ship1(ΔDC) mice. Our results describe a critical role for SHIP-1 in regulating the ability of DCs to efficiently prime Th2-type responses.

Low-Dose Intestinal Trichuris muris Infection Alters the Lung Immune Microenvironment and Can Suppress Allergic Airway Inflammation.

Immunological cross talk between mucosal tissues such as the intestine and the lung is poorly defined during homeostasis and disease. Here, we show that a low-dose infection with the intestinally restricted helminth parasite Trichuris muris results in the production of Th1 cell-dependent gamma interferon (IFN-γ) and myeloid cell-derived interleukin-10 (IL-10) in the lung without causing overt airway pathology. This cross-mucosal immune response in the lung inhibits the development of papain-induced allergic airway inflammation, an innate cell-mediated type 2 airway inflammatory disease. Thus, we identify convergent and nonredundant roles of adaptive and innate immunity in mediating cross-mucosal suppression of type 2 airway inflammation during low-dose helminth-induced intestinal inflammation. These results provide further insight in identifying novel intersecting immune pathways elicited by gut-to-lung mucosal cross talk.

The orphan nuclear receptor ROR alpha and group 3 innate lymphoid cells drive fibrosis in a mouse model of Crohn's disease.

Fibrosis is the result of dysregulated tissue regeneration and is characterized by excessive accumulation of matrix proteins that become detrimental to tissue function. In Crohn's disease, this manifests itself as recurrent gastrointestinal strictures for which there is no effective therapy beyond surgical intervention. Using a model of infection-induced chronic gut inflammation, we show that Rora-deficient mice are protected from fibrosis; infected intestinal tissues display diminished pathology, attenuated collagen deposition and reduced fibroblast accumulation. Although Rora is best known for its role in ILC2 development, we find that Salmonella-induced fibrosis is independent of eosinophils, STAT6 signaling and Th2 cytokine production arguing that this process is largely ILC2-independent. Instead, we observe reduced levels of ILC3- and T cell-derived IL-17A and IL-22 in infected gut tissues. Furthermore, using Rorasg/sg /Rag1-/- bone marrow chimeric mice, we show that restoring ILC function is sufficient to re-establish IL-17A and IL-22 production and a profibrotic phenotype. Our results show that RORα-dependent ILC3 functions are pivotal in mediating gut fibrosis and they offer an avenue for therapeutic intervention in Crohn's-like diseases.

The orphan nuclear receptor RORα and group 3 innate lymphoid cells drive fibrosis in a mouse model of Crohn's disease.

Fibrosis is the result of dysregulated tissue regeneration and is characterized by excessive accumulation of matrix proteins that become detrimental to tissue function. In Crohn's disease, this manifests itself as recurrent gastrointestinal strictures for which there is no effective therapy beyond surgical intervention. Using a model of infection-induced chronic gut inflammation, we show that Rora-deficient mice are protected from fibrosis; infected intestinal tissues display diminished pathology, attenuated collagen deposition, and reduced fibroblast accumulation. Although Rora is best known for its role in group 2 innate lymphoid cell (ILC2) development, we find that Salmonella-induced fibrosis is independent of eosinophils, signal transducer and activator of transcription 6 signaling, and T helper 2 cytokine production, arguing that this process is largely ILC2-independent. Instead, we observe reduced levels of ILC3- and T cell-derived interleukin-17A (IL-17A) and IL-22 in infected gut tissues. Furthermore, using Rorasg/sg /Rag1-/- bone marrow chimeric mice, we show that restoring ILC function is sufficient to reestablish IL-17A and IL-22 production and a profibrotic phenotype. Our results show that RORα (retinoic acid receptor-related orphan receptor α)-dependent ILC3 functions are pivotal in mediating gut fibrosis, and they offer an avenue for therapeutic intervention in Crohn's-like diseases.

Lineage-specific regulation of allergic airway inflammation by the lipid phosphatase Src homology 2 domain-containing inositol 5-phosphatase (SHIP-1).

BACKGROUND: Inpp5d (Src homology 2 domain-containing inositol-5-phosphatase [Ship1])-deficient mice experience spontaneous airway inflammation and have enhanced sensitivity to allergen-induced airway inflammation. OBJECTIVE: We hypothesized that lineage-specific deletion of Ship1 expression in cells known to be crucial for adaptive TH2 responses would uncover distinct roles that could either positively or negatively regulate susceptibility to allergic airway inflammation (AAI). METHODS: Ship1 expression was deleted in B cells, T cells, or dendritic cells (DCs), and the resulting Ship1(ΔB cell), Ship1(ΔT cell), Ship1(ΔDC), or Ship1(F/F) (wild-type) control mice were evaluated in a model of house dust mite (HDM)-induced AAI. RESULTS: Unlike germline panhematopoietic Ship1 deletion, deletion of Ship1 selectively in either the B-cell, T-cell, or DC lineages did not result in spontaneous airway inflammation. Strikingly, although loss of Ship1 in the B-cell lineage did not affect HDM-induced AAI, loss of Ship1 in either of the T-cell or DC lineages protected mice from AAI by skewing the typical TH2 immune response toward a TH1 response. CONCLUSIONS: Although panhematopoietic deletion of Ship1 leads to spontaneous lung inflammation, selective deletion of Ship1 in T cells or DCs impairs the formation of an adaptive TH2 response and protects animals from HDM-induced AAI.

Regulation of CD4 T-cell differentiation and inflammation by repressive histone methylation.

Repressive epigenetic modifications such as dimethylation and trimethylation histone H3 at lysine 9 (H3K9me2 and H3K9me3) and H3K27me3 have been shown to be critical for embryonic stem (ES) cell differentiation by silencing cell lineage-promiscuous genes. CD4(+) T helper (T(H)) cell differentiation is a powerful model to study the molecular mechanisms associated with cellular lineage choice in adult cells. Naïve T(H) cells have the capacity to differentiate into one of the several phenotypically and functionally distinct and stable lineages. Although some repressive epigenetic mechanisms have a critical role in T(H) cell differentiation in a similar manner to that in ES cells, it is clear that there are disparate functions for certain modifications between ES cells and T(H) cells. Here we review the role of repressive histone modifications in the differentiation and function of T(H) cells in health and disease.

Group 2 innate lymphoid cells facilitate sensitization to local, but not systemic, TH2-inducing allergen exposures.

BACKGROUND: Allergic inflammation involves the sensitization of naive CD4(+) T cells to allergens, resulting in a TH2-skewed inflammatory response. Although antigen presentation by dendritic cells to T cells in the lymph node is crucial for TH2 cell development, the innate signals that initiate adaptive type 2 inflammation and the role of group 2 innate lymphoid cells (ILC2s) are poorly understood. OBJECTIVE: We sought to investigate the influence of ILC2s and the route of priming on the development of an adaptive type 2 immune response to lung allergens. METHODS: Wild-type and ILC2-deficient mice were exposed intranasally or systemically to the TH2-inducing antigens house dust mite or ovalbumin in a model of allergic airway inflammation or the TH17-inducing bacterial antigen Saccharopolyspora rectivirgula in a model of hypersensitivity pneumonitis. The formation of an adaptive immune response was evaluated based on serum antibody titers and production of T cell-derived cytokines (IL-4, IL-5, IL-13 and IL-17A). RESULTS: We find that lung ILC2s play a critical role in priming the adaptive type 2 immune response to inhaled allergens, including the recruitment of eosinophils, TH2 cytokine production and serum IgE levels. Surprisingly, systemic priming with ovalbumin, with or without adjuvants, circumvents the requirement for ILC2s in inducing TH2-driven lung inflammation. ILC2s were also found to be dispensable for the sensitization to TH1- or TH17-inducing antigens. CONCLUSION: These data highlight a critical role for ILC2s in the development of adaptive type 2 responses to local, but not systemic, antigen exposure.

Methyltransferase G9A regulates T cell differentiation during murine intestinal inflammation.

Inflammatory bowel disease (IBD) pathogenesis is associated with dysregulated CD4⁺ Th cell responses, with intestinal homeostasis depending on the balance between IL-17-producing Th17 and Foxp3⁺ Tregs. Differentiation of naive T cells into Th17 and Treg subsets is associated with specific gene expression profiles; however, the contribution of epigenetic mechanisms to controlling Th17 and Treg differentiation remains unclear. Using a murine T cell transfer model of colitis, we found that T cell-intrinsic expression of the histone lysine methyltransferase G9A was required for development of pathogenic T cells and intestinal inflammation. G9A-mediated dimethylation of histone H3 lysine 9 (H3K9me2) restricted Th17 and Treg differentiation in vitro and in vivo. H3K9me2 was found at high levels in naive Th cells and was lost following Th cell activation. Loss of G9A in naive T cells was associated with increased chromatin accessibility and heightened sensitivity to TGF-ß1. Pharmacological inhibition of G9A methyltransferase activity in WT T cells promoted Th17 and Treg differentiation. Our data indicate that G9A-dependent H3K9me2 is a homeostatic epigenetic checkpoint that regulates Th17 and Treg responses by limiting chromatin accessibility and TGF-ß1 responsiveness, suggesting G9A as a therapeutic target for treating intestinal inflammation.

The retinoic acid-metabolizing enzyme Cyp26b1 regulates CD4 T cell differentiation and function.

The vitamin A metabolite retinoic acid (RA) has potent immunomodulatory properties that affect T cell differentiation, migration and function. However, the precise role of RA metabolism in T cells remains unclear. Catabolism of RA is mediated by the Cyp26 family of cytochrome P450 oxidases. We examined the role of Cyp26b1, the T cell-specific family member, in CD4(+) T cells. Mice with a conditional knockout of Cyp26b1 in T cells (Cyp26b1 (-/-) mice) displayed normal lymphoid development but showed an increased sensitivity to serum retinoids, which led to increased differentiation under both inducible regulatory T (iTreg) cell- and TH17 cell-polarizing conditions in vitro. Further, Cyp26b1 expression was differentially regulated in iTreg and TH17 cells. Transfer of naïve Cyp26b1 (-/-) CD4(+) T cells into Rag1 (-/-) mice resulted in significantly reduced disease in a model of T cell-dependent colitis. Our results show that T cell-specific expression of Cyp26b1 is required for the development of T cell-mediated colitis and may be applicable to the development of therapeutics that target Cyp26b1 for the treatment of inflammatory bowel disease.

Control of the hippo pathway by Set7-dependent methylation of Yap.

Methylation of nonhistone proteins is emerging as a regulatory mechanism to control protein function. Set7 (Setd7) is a SET-domain-containing lysine methyltransferase that methylates and alters function of a variety of proteins in vitro, but the in vivo relevance has not been established. We found that Set7 is a modifier of the Hippo pathway. Mice that lack Set7 have a larger progenitor compartment in the intestine, coinciding with increased expression of Yes-associated protein (Yap) target genes. Mechanistically, monomethylation of lysine 494 of Yap is critical for cytoplasmic retention. These results identify a methylation-dependent checkpoint in the Hippo pathway.

Requirement for core 2 O-glycans for optimal resistance to helminth infection.

The migration of lymphocytes to the small intestine is controlled by expression of the integrin α4ß7 and the chemokine receptor CCR9. However, the molecules that specifically regulate migration to the large intestine remain unclear. Immunity to infection with the large intestinal helminth parasite Trichuris muris is dependent upon CD4(+) T cells that migrate to the large intestine. We examine the role of specific chemokine receptors, adhesion molecules and glycosyltransferases in the development of protective immunity to Trichuris. Mice deficient in expression of the chemokine receptors CCR2 or CCR6 were resistant to infection with Trichuris. Similarly, loss of CD34, CD43, CD44 or PSGL-1 had no effect on resistance to infection. In contrast, simultaneous deletion of the Core2 ß1,6-N-acetylglucosaminyltransferase (C2GnT) enzymes C2GnT1 and C2Gnt2 resulted in delayed expulsion of worms. These results suggest that C2GnT-dependent modifications may play a role in migration of protective immune cells to the large intestine.

The role of SHIP in the development and activation of mouse mucosal and connective tissue mast cells.

Although SHIP is a well-established suppressor of IgE plus Ag-induced degranulation and cytokine production in bone marrow-derived mast cells (BMMCs), little is known about its role in connective tissue (CTMCs) or mucosal (MMCs) mast cells. In this study, we compared SHIP's role in the development as well as the IgE plus Ag and TLR-induced activation of CTMCs, MMCs, and BMMCs and found that SHIP delays the maturation of all three mast cell subsets and, surprisingly, that it is a positive regulator of IgE-induced BMMC survival. We also found that SHIP represses IgE plus Ag-induced degranulation of all three mast cell subsets and that TLR agonists do not trigger their degranulation, whether SHIP is present or not, nor do they enhance IgE plus Ag-induced degranulation. In terms of cytokine production, we found that in MMCs and BMMCs, which are poor producers of TLR-induced cytokines, SHIP is a potent negative regulator of IgE plus Ag-induced IL-6 and TNF-α production. Surprisingly, however, in splenic or peritoneal derived CTMCs, which are poor producers of IgE plus Ag-induced cytokines, SHIP is a potent positive regulator of TLR-induced cytokine production. Lastly, cell signaling and cytokine production studies with and without LY294002, wortmannin, and PI3Kα inhibitor-2, as well as with PI3K p85α(-/-) BMMCs and CTMCs, are consistent with SHIP positively regulating TLR-induced cytokine production via an adaptor-mediated pathway while negatively regulating IgE plus Ag-induced cytokine production by repressing the PI3K pathway.

SHIP-deficient dendritic cells, unlike wild type dendritic cells, suppress T cell proliferation via a nitric oxide-independent mechanism.

BACKGROUND: Dendritic cells (DCs) not only play a crucial role in activating immune cells but also suppressing them. We recently investigated SHIP's role in murine DCs in terms of immune cell activation and found that TLR agonist-stimulated SHIP-/- GM-CSF-derived DCs (GM-DCs) were far less capable than wild type (WT, SHIP+/+) GM-DCs at activating T cell proliferation. This was most likely because SHIP-/- GM-DCs could not up-regulate MHCII and/or co-stimulatory receptors following TLR stimulation. However, the role of SHIP in DC-induced T cell suppression was not investigated. METHODOLOGY/PRINCIPAL FINDINGS: In this study we examined SHIP's role in DC-induced T cell suppression by co-culturing WT and SHIP-/- murine DCs, derived under different conditions or isolated from spleens, with αCD3+ αCD28 activated WT T cells and determined the relative suppressive abilities of the different DC subsets. We found that, in contrast to SHIP+/+ and -/- splenic or Flt3L-derived DCs, which do not suppress T cell proliferation in vitro, both SHIP+/+ and -/- GM-DCs were capable of potently suppressing T cell proliferation. However, WT GM-DC suppression appeared to be mediated, at least in part, by nitric oxide (NO) production while SHIP-/- GM-DCs expressed high levels of arginase 1 and did not produce NO. Following exhaustive studies to ascertain the mechanism of SHIP-/- DC-mediated suppression, we could conclude that cell-cell contact was required and the mechanism may be related to their relative immaturity, compared to SHIP+/+ GM-DCs. CONCLUSIONS: These findings suggest that although both SHIP+/+ and -/- GM-DCs suppress T cell proliferation, the mechanism(s) employed are different. WT GM-DCs suppress, at least in part, via IFNγ-induced NO production while SHIP-/- GM-DCs do not produce NO and suppression can only be alleviated when contact is prevented.

Trichuris muris infection: a model of type 2 immunity and inflammation in the gut.

Trichuris muris is a natural pathogen of mice and is biologically and antigenically similar to species of Trichuris that infect humans and livestock. 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 environment. 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. 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. 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.