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/β-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.

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

Antignano, Zaph, and collaborators show that the lysine methyltransferase G9a plays a critical role in determining the developmental programs of group 2 and 3 innate lymphoid cells.

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.

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-β1. 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-β1 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 (iT_reg) cell- and T_H17 cell-polarizing conditions in vitro. Further, Cyp26b1 expression was differentially regulated in iT_reg and T_H17 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.

Epigenetic licensing of Th17 and Treg cell differentiation (P1197)

Naïve CD4+ T helper (Th) cells acquire a range of fates depending on the cytokine milieu and anatomical location. For example, IL-17 producing Th17 and Foxp3+ regulatory (Treg) cells are dependent upon TGFβ1 and are critical for intestinal homeostasis. G9a is a histone lysine methyltransferase with di-methyl activity towards histone H3 lysine 9. H3K9me2 is a highly conserved histone modification and is commonly linked to transcriptional repression. In this study we examine the role of G9a in the control of Th17 and Treg cell differentiation. Using chromatin immunoprecipitation (ChIP) we found that there is a concomitant loss H3K9me2 and increase in H3K9Ac (an activating histone modification) at lineage specific genes of WT Th17 and Treg cells compared to naive. Meanwhile, naïve G9a-/- T cells have low levels H3K9me2 that results in enhanced sensitivity to TGFβ1 and an increase in the differentiation of both Th17 and Treg cells in vitro. Using the T cell transfer colitis model, we found that transfer of G9a-deficient T cells fails to cause the weight loss and colonic inflammation typical of the model. Furthermore, T effector-cell production of IFNγ was significantly reduced and IL-17 was enhanced when G9a-/- T cells were transferred. In addition, compared to WT controls, a higher proportion of G9a-deficient T cells express Foxp3. We conclude that G9a-dependent H3K9me2 is a homeostatic epigenetic checkpoint that controls the magnitude of Th17 and Treg cell responses.

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 α4β7 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 β1,6-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.

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.

Assessing the role of CD103 in immunity to an intestinal helminth parasite

Background

In the intestine, the integrin CD103 is expressed on a subset of T regulatory (T_reg) cells and a population of dendritic cells (DCs) that produce retinoic acid and promote immune homeostasis. However, the role of CD103 during intestinal helminth infection has not been tested.

Methodology/Principal Findings

We demonstrate that CD103 is dispensable for the development of protective immunity to the helminth parasite Trichuris muris. While we observed an increase in the frequency of CD103⁺ DCs in the lamina propria (LP) following acute high-dose infection with Trichuris, lack of CD103 had no effect on the frequency of CD11c⁺ DCs in the LP or mesenteric lymph nodes (mLN). CD103-deficient (CD103^−/−) mice develop a slightly increased and earlier T cell response but resolve infection with similar kinetics to control mice. Similarly, low-dose chronic infection of CD103^−/− mice with Trichuris resulted in no significant difference in immunity or parasite burden. Absence of CD103 also had no effect on the frequency of CD4⁺CD25⁺Foxp3⁺ T_reg cells in the mLN or LP.

Conclusions/Significance

These results suggest that CD103 is dispensable for intestinal immunity during helminth infection. Furthermore, lack of CD103 had no effect on DC or T_reg recruitment or retention within the large intestine.

Activating and inhibitory functions for the histone lysine methyltransferase G9a in T helper cell differentiation and function

Accumulating evidence suggests that the regulation of gene expression by histone lysine methylation is crucial for several biological processes. The histone lysine methyltransferase G9a is responsible for the majority of dimethylation of histone H3 at lysine 9 (H3K9me2) and is required for the efficient repression of developmentally regulated genes during embryonic stem cell differentiation. However, whether G9a plays a similar role in adult cells is still unclear. We identify a critical role for G9a in CD4⁺ T helper (Th) cell differentiation and function. G9a-deficient Th cells are specifically impaired in their induction of Th2 lineage-specific cytokines IL-4, IL-5, and IL-13 and fail to protect against infection with the intestinal helminth Trichuris muris. Furthermore, G9a-deficient Th cells are characterised by the increased expression of IL-17A, which is associated with a loss of H3K9me2 at the Il17a locus. Collectively, our results establish unpredicted and complex roles for G9a in regulating gene expression during lineage commitment in adult CD4⁺ T cells.

Dendritic cell-expressed CD103 is required for inhibition of mucosal Th2 cell responses (90.3)

Dysregulated mucosal CD4 Th2 cell responses are a feature of several inflammatory diseases including asthma, allergies and some forms of inflammatory bowel disease. The integrin CD103 is expressed primarily on a subset of dendritic cells (DCs) that promote regulatory T cell development and intestinal immune homeostasis. However, the role of CD103 in Th2-dependent immunity has not been tested. Using the helminth parasite Trichuris muris, we identify a critical role for CD103 in specifically limiting Th2 responses in vivo. We find that following infection with Trichuris, CD103-deficient (CD103-/-) mice develop an enhanced Th2 response that is associated with decreased levels of IL-10. While in vitro CD4 T cell differentiation was unaffected by CD103 deficiency, bone marrow-derived CD103-/- DCs induce heightened T cell proliferation and increased IL-13 production under Th2 promoting conditions. The inhibitory role of CD103 appears to be specific for Th2 responses, as CD103-/- mice are protected from disease development in a model of chemically-induced colitis. Taken together, these results suggest that CD103 expression on DCs is critically required to specifically regulate Th2 immune responses in vivo.

Psychiatric illness in women: a review of the function of a specialist mother-baby unit

OBJECTIVE

The aim of this paper is to describe a specialist program in a psychiatric mother-baby unit and to review the characteristics (including mothering skills) and outcomes on discharge of 36 women consecutively admitted to the unit over an intensive 6-month observation period. Changes in admissions to the same unit over 10 years were also compared.

METHOD

Consecutive admissions were studied in terms of demographics, ethnicity, diagnosis, psychiatric history, psychiatric information and mother-infant data.

RESULTS

The majority of women admitted suffered from schizophrenia or other psychotic disorders, with the second largest diagnostic criteria being depression. For 20 mothers, this was the first psychiatric admission and most admissions were voluntary. The mean length of stay was 21.7 days, representing a highly significant decrease in stay when compared to the past 10 years in the same unit. Mothering skills were found to be incompetent or only passable in 57% of women. A small improvement occurred by discharge, and the majority of women were not separated from their infants.

CONCLUSIONS

The critical need to support these women and their infants in the long term was highlighted, with recommendations of outpatient and day programs, as well as supported accommodation.

Overcoming obstacles: challenges of caring for an urban pediatric population

There are many challenges to working with pediatric patients at home, and they are complicated when the family lives in the inner city. The VNA of Boston has overcome many of the challenges through its unique Maternal Child Health team--a good model for any pediatric care team.

A peptidergic circuit for reproductive behavior

A projection from the medial amygdaloid nucleus to the hippocampus and septum probably uses vasopressin as a transmitter. The nucleus synthesizes vasopressin and activation of the nucleus has a hippocampal effect that is completely blocked by a vasopressin antagonist. The afferent and efferent projections of this peptidergic nucleus suggest a possible role for the system in sexual behavior. Stimulation of the nucleus inhibits the output of the hippocampus in both genders and reorganizes behavior for a period of 15-20 min. In males, the effect of peptidergic activation is to produce a behavior that resembles the post-ejaculatory interval in coitus. This state is characterized by an EEG that resembles slow-wave sleep and by ultrasonic vocalizations at a characteristic frequency of 22 kHz. Castration in either gender causes depletion of the peptide from the target fields and eliminates the peptidergic signal in the hippocampus after about 15 weeks. The effects of castration in males can be reversed by testosterone replacement. The fluctuation of estrogen levels in rat plasma during the estrus cycle happens too quickly to impact the peptidergic system, and thus there is no significant change in the strength of the peptidergic signal among the proestrus, estrus, metestrus and diestrus stages. This fact permits study of the physiology of the system without concern for stage of estrus but does not permit conclusions regarding its function in females.

Cardiovascular and pharmacokinetic effects of isoxsuprine in the horse

Isoxsuprine (0.6 mg/kg) administered IV to 6 standing horses produced substantial, transient decreases in systemic blood pressure, systemic vascular resistance, and stroke volume. It also produced substantial, transient increases in heart rate, cardiac output, and purposeful movement. Plasma concentrations of isoxsuprine peaked soon after the drug was administered IV and then decreased over a 12-hour period in a biexponential manner, with distribution and elimination half-lives of 14 minutes and 2.67 hours, respectively. Total body clearance and steady-state volume of distribution were calculated to be 53.8 ml/min/kg and 10.5 L/kg, respectively. When a recommended therapeutic dosage regimen (0.6 mg/kg 2 times a day, per os) was used in 4 of these horses, changes were not detected. Isoxsuprine was not detected in plasma after the drug was given orally. We conclude that 0.6 mg of isoxsuprine/kg given orally every 12 hours is not likely to produce cardiovascular changes in the resting horse and that this is probably because plasma concentrations are not high enough to do so.

Hospital costs and return to work after coronary bypass surgery

A study to assess the cost and some of the benefits of coronary bypass surgery was carried out at the Alfred Hospital, Melbourne. The minimum cost to the hospital of a typical coronary bypass graft procedure in 1980 was estimated to be $4700. The benefit of the procedure in terms of symptomatic relief and return to work was assessed by means of questionnaires. In the working-age group (55 years and under) of 591 patients, assessed from two to nine years after surgery, 68% of patients were working. In a group of 100 patients, aged 55 years and under, and interviewed from one to two years after surgery, 56 patients were working before surgery, but only 16 of these at full capacity. After surgery, 78 patients were working; 64 of these at full capacity. The cost of a coronary bypass graft operation is considerable, but this is offset in the majority of patients in the working-age group by a return to gainful employment.