Project description:Gene expression of Treg cells that have lost Foxp3 expression and acquired Il4 expression following adoptive transfer into T-cell deficient mice (HpTR-IL-4gfp+), cmpared to conventional Treg cells isolated from H. polygyrus-infected wild-type mice (HpTR) and Th2 cells generated from naïve T cells following adoptive transfer into H. polygyrus-infected T-cell deficient mice (nT-IL-4gfp+). Immunity to intestinal helminth infections requires the rapid activation of T helper 2 (Th2) cells. However, simultaneous expansion of regulatory CD4+Foxp3+ T (Treg) cells impedes protective responses, resulting in chronic infections. The ratio between regulatory and effector T cells can therefore determine the outcome of infection. The re-differentiation of Treg into T helper (Th) cells has been identified in hyper-inflammatory diseases. In this study, we asked whether ex-Treg Th2 cells develop and contribute to type 2 immunity. Using multi-gene reporter and fate-reporter systems we demonstrate that a significant proportion of Th2 cells derive from Foxp3+ cells following Heligmosomoides polygyrus infection and airway allergy. Ex-Foxp3 Th2 cells exhibit characteristic Th2 effector functions and provide immunity to H. polygyrus. Through selective deletion of Il4ra on Foxp3+ cells, we further demonstrate IL-4 is required for the development of ex-Foxp3 Th2 cells. Collectively, our findings indicate that converting Treg cells into Th2 cells could concomitantly enhance Th2 cells and limit Treg-mediated suppression.
Project description:The cytokines GM-CSF and IL-5 are thought to possess largely divergent functions despite a shared dependence on the common beta (βC) chain to initiate signaling. Although IL-5 is part of the core type 2 cytokine signature and is required for protection against some helminths, it is dispensable for immunity to others, such as Heligmosomoides polygyrus bakeri (H. polygyrus). Whether this is due to compensatory mechanisms is unclear. The transcription factor Bhlhe40 has been shown to control GM-CSF production and is proposed to be a novel regulator of T helper type 2 cells. We have found that Bhlhe40 is required in T cells for a protective memory response to secondary H. polygyrus infection. H. polygyrus rechallenge elicited dramatic Bhlhe40-dependent changes in gene and cytokine expression by lamina propria CD4+ T cells and in vitro-polarized TH2 cells, including induction of GM-CSF and maximal production of type 2 cytokines including IL-5. βC chain-deficient, but not GM-CSF-deficient, mice rechallenged with H. polygyrus had severely impaired protective immunity. Our results demonstrate that Bhlhe40 is an essential regulator of TH2 cell immunity during helminth infection and reveal unexpected redundancy of βC chain-dependent cytokines.
Project description:Four microRNAs(miRNAs) highly abundantly secreted by the parasitic nematode Heligmosomoides polygyrus were synthesized (miRVana, Ambion) and transfected repeatedly into differentiating Th2 cells in vitro, individually or in combination. The effects of the different transfection regimens were assessed by RNA sequencing (Illumina).
Project description:Intestinal parasitic nematodes, affecting a quarter of the world’s population, typically elicit prominent effector Th2-driven host immune responses. However, a more detailed understanding of nematode-induced memory Th2 responses remains scarce. We investigated the activation of peritoneal memory Th2 cells and the mechanisms driving early recall responses to the enteric nematode Heligmosomoides polygyrus in mice. We show memory Th2 cells with distinct transcriptional profiles to persist systemically in lymphoid and non-lymphoid tissues following cure of infection. Moreover, peritoneal memory Th2 cells display strong cytokine production, upregulate costimulatory marker Ox40 (CD134) and IL-5 production in a parasite-specific manner as early as 3 days following challenge infection. This effect is paralleled by an influx of Ox40L+ dendritic cells (DC) and eosinophils, both appearing exclusively in the peritoneum of reinfected mice. Finally, we show that peritoneal mesothelial cells (PeM) significantly downregulate their expression of VCAM-1 and ICAM-1 in response to a secondary infection, pointing towards an involvement in immune cell efflux. Thus, our data indicate a pivotal role of the peritoneum for memory Th2 responses and a role for PeM cells in immune cell recruitment, activation and efflux during recall responses to a strictly intestinal pathogen.
Project description:The intestinal helminth parasite Heligmosomoides polygyrus initiates infection in mice by penetrating the duodenal mucosa, where it develops while surrounded by a multicellular granulomatous infiltrate before emerging into the intestinal lumen. We examined early H. polygyrus infection to assess the epithelial response to disruption of the mucosal barrier. Unexpectedly, intestinal stem cell markers, including Lgr5 and Olfm4, were completely lost in crypts overlying larvae-associated granulomas. We sought to identify the mechanism by which the H. polygyrus granuloma represses the activity of intestinal stem cells.
Project description:Gene expression profile of dendritic cells (DC) of mesenteric lymph node (mLN) and lamina propria of small intestine (SI-LP) of control mice and mice lacking RelB expression in DCs at steady state, four days and 14 days after infection with Heligmosomoides polygyrus bakeri (Hpb) Dendritic cells (DCs) are crucial for initiating protective immune responses and have also been implicated in the generation and regulation of Foxp3+ regulatory T cells (Tregs). Specific DC subsets or DC-intrinsic pathways regulate immunity against pathogens but also tolerance to harmless antigens derived from food or microbiota at barrier sites, but underlying mechanisms in the intestinal tract remain poorly defined. Here, we provide evidence that the alternative NF-B family member RelB controls a defined transcriptional program in migratory DC subsets of mesenteric lymph nodes and the small intestinal lamina propria. Functionally, ablation of RelB in dendritic cells result in increased Foxp3+ Treg cell numbers but decreased RORt peripheral Treg cell numbers maintained even under inflammatory conditions. Single-cell RNA-sequencing revealed a complete RelB dependency for the differentiation of cryptopatches and isolated lymphoid follicles-associated DCs (CIA-DCs) in the lamina propria of the small intestine. In addition, we show a RelB-dependent signature of migratory DCs in mesenteric lymph nodes favoring DC-Treg cell interaction by affecting the expression of chemokines (Ccl22, Ccl17), migration behavior (Cd63), co-stimulatory molecule (Cd80, Cd40, Cd200, Tnfsf4), and tolerance-related integrin (Itgb5, Itgb8) expression. Functionally, increased Treg cell numbers in DC-specific RelB knockout animals did not show any risk of increased reactions in a model of food allergy but instead prevented protective Th2 immune responses in the intestines after infection with Heligmosomoides polygyrus bakeri despite their slight steady-state type 2 immune bias. This protection was dependent on elevated Treg cell frequencies during primary infection as a result of bystander immune tolerance. Thus, RelB expression in conventional DCs acts as a rheostat to establish a tolerogenic set point that is maintained even during infection and strong type 2 immune conditions and thereby is a key regulator of intestinal homeostasis.
Project description:Mouse bone marrow derived macrophages were stimulated with L3 larvae of the helminth Heligmosomoides polygyrus (Hp) (500 L3 /1 mio cells) in the presence or absence of immune serum (1:50 v:v) from challenge-Hp-infected mice.