Effects of duration of exposure, co-supplementation with iron and Nippostrongylus brasiliensis infection on accumulation of trichloroacetic acid-insoluble copper in rats given molybdate in drinking water.

Thiolation can convert molybdate (MoO4) into a series of thiomolybdates (MoSxO4-x) in the rumen, terminating in tetrathiomolybdate (MoS4), a potent antagonist of copper absorption and, if absorbed, donor of reactive sulphide in tissues. Systemic exposure to MoS4 increases trichloroacetic acid-insoluble copper (TCAI Cu) concentrations in the plasma of ruminants and induction of TCAI Cu in rats given MoO4 in drinking water would support the hypothesis that rats, like ruminants, can thiolate MoO4. Data on TCAI Cu are presented from two experiments involving MoO4 supplementation that had broader objectives. In experiment 1, plasma Cu concentrations (P Cu) tripled in female rats infected with Nippostrongylus brasiliensis after only 5 days exposure to drinking water containing 70 mg Mo L-1, due largely to an increase in TCAI Cu; activities of erythrocyte superoxide dismutase and plasma caeruloplasmin oxidase (CpOA) were unaffected. Exposure for 45-51 days did not raise P Cu further but TCA-soluble (TCAS) Cu concentrations increased temporarily 5 days post infection (dpi) and weakened the linear relationship between CpOA and TCAS Cu. In experiment 2, infected rats were given less MoO4 (10 mg Mo L-1), with or without iron (Fe, 300 mg L-1), for 67 days and killed 7 or 9 dpi. P Cu was again tripled by MoO4 but co-supplementation with Fe reduced TCAI Cu from 65 ± 8.9 to 36 ± 3.8 µmol L-l. Alone, Fe and MoO4 each reduced TCAS Cu in females and males when values were higher (7 and 9 dpi, respectively). Thiolation probably occurred in the large intestine but was inhibited by precipitation of sulphide as ferrous sulphide. Fe alone may have inhibited caeruloplasmin synthesis during the acute phase response to infection, which impacts thiomolybdate metabolism.

A Strategy for the Study of IL-9-Producing Lymphoid Cells in the Nippostrongylus brasiliensis Infection Model.

IL-9 is a pleiotropic cytokine associated with various processes, including antitumor immunity, induction of allergic pathologies, and the immune response against helminth infections, where it plays an important role in the expulsion of the parasite. In a murine model of Nippostrongylus brasiliensis infection, IL-9 is produced mainly by CD4+ T lymphocytes and innate lymphoid cells found in the lung, small intestine, and draining lymph nodes. Given the technical difficulties involved in the intracellular staining of IL-9, as well as the complexity of isolating hematopoietic cells from the small intestine upon infection, there is a pressing need for a comprehensive but straightforward protocol to analyze the expression of IL-9 in different lymphoid and non-lymphoid tissues in this model. The protocol described here outlines the kinetics of IL-9 produced by CD4+ T cells and innate lymphoid cells in the lung and small intestine, the main organs targeted by N. brasiliensis, as well as in the mediastinal and mesenteric lymph nodes, throughout the infection. In addition, it details the number of larvae needed for infection, depending on the cell type and organ of interest. This protocol aims to assist in the standardization of assays to save time and resources by offering the opportunity to focus on the specific cells, organs, and disease stages of interest in the N. brasiliensis infection model.

IL-4 and helminth infection downregulate MINCLE-dependent macrophage response to mycobacteria and Th17 adjuvanticity.

The myeloid C-type lectin receptor (CLR) MINCLE senses the mycobacterial cell wall component trehalose-6,6'-dimycolate (TDM). Recently, we found that IL-4 downregulates MINCLE expression in macrophages. IL-4 is a hallmark cytokine in helminth infections, which appear to increase the risk for mycobacterial infection and active tuberculosis. Here, we investigated functional consequences of IL-4 and helminth infection on MINCLE-driven macrophage activation and Th1/Th17 adjuvanticity. IL-4 inhibited MINCLE and cytokine induction after macrophage infection with Mycobacterium bovis bacille Calmette-Guerin (BCG). Infection of mice with BCG upregulated MINCLE on myeloid cells, which was inhibited by IL-4 plasmid injection and by infection with the nematode Nippostrongylus brasiliensis in monocytes. To determine the impact of helminth infection on MINCLE-dependent immune responses, we vaccinated mice with a recombinant protein together with the MINCLE ligand trehalose-6,6-dibehenate (TDB) as adjuvant. Concurrent infection with N. brasiliensis or with Schistosoma mansoni promoted T cell-derived IL-4 production and suppressed Th1/Th17 differentiation in the spleen. In contrast, helminth infection did not reduce Th1/Th17 induction by TDB in draining peripheral lymph nodes, where IL-4 levels were unaltered. Upon use of the TLR4-dependent adjuvant G3D6A, N. brasiliensis infection impaired selectively the induction of splenic antigen-specific Th1 but not of Th17 cells. Inhibition of MINCLE-dependent Th1/Th17 responses in mice infected with N. brasiliensis was dependent on IL-4/IL-13. Thus, helminth infection attenuated the Th17 response to MINCLE-dependent immunization in an organ- and adjuvant-specific manner via the Th2 cytokines IL-4/IL-13. Taken together, our results demonstrate downregulation of MINCLE expression on monocytes and macrophages by IL-4 as a possible mechanism of thwarted Th17 vaccination responses by underlying helminth infection.

Administration of Hookworm Excretory/Secretory Proteins Improves Glucose Tolerance in a Mouse Model of Type 2 Diabetes.

Diabetes is recognised as the world's fastest growing chronic condition globally. Helminth infections have been shown to be associated with a lower prevalence of type 2 diabetes (T2D), in part due to their ability to induce a type 2 immune response. Therefore, to understand the molecular mechanisms that underlie the development of T2D-induced insulin resistance, we treated mice fed on normal or diabetes-promoting diets with excretory/secretory products (ES) from the gastrointestinal helminth Nippostrongylus brasiliensis. We demonstrated that treatment with crude ES products from adult worms (AES) or infective third-stage larvae (L3ES) from N. brasiliensis improved glucose tolerance and attenuated body weight gain in mice fed on a high glycaemic index diet. N. brasiliensis ES administration to mice was associated with a type 2 immune response measured by increased eosinophils and IL-5 in peripheral tissues but not IL-4, and with a decrease in the level of IL-6 in adipose tissue and corresponding increase in IL-6 levels in the liver. Moreover, treatment with AES or L3ES was associated with significant changes in the community composition of the gut microbiota at the phylum and order levels. These data highlight a role for N. brasiliensis ES in modulating the immune response associated with T2D, and suggest that N. brasiliensis ES contain molecules with therapeutic potential for treating metabolic syndrome and T2D.

Expelliarmus helminthus! Harry Helminth and the Goblet of Alarmins.

Epithelial cells (tuft and goblet cells) interact with immune cells on the "inside" while secreting effector molecules into the topological "outside." In this issue of Immunity, Zhao et al. investigate an interleukin-33 (IL-33) secretion mechanism in goblet cells dependent on O-GlcNAcylation and gasdermin pores facilitating worm expulsion.

Helminth resistance is mediated by differential activation of recruited monocyte-derived alveolar macrophages and arginine depletion.

Macrophages are known to mediate anti-helminth responses, but it remains uncertain which subsets are involved or how macrophages actually kill helminths. Here, we show rapid monocyte recruitment to the lung after infection with the nematode parasite Nippostrongylus brasiliensis. In this inflamed tissue microenvironment, these monocytes differentiate into an alveolar macrophage (AM)-like phenotype, expressing both SiglecF and CD11c, surround invading parasitic larvae, and preferentially kill parasites in vitro. Monocyte-derived AMs (Mo-AMs) express type 2-associated markers and show a distinct remodeling of the chromatin landscape relative to tissue-derived AMs (TD-AMs). In particular, they express high amounts of arginase-1 (Arg1), which we demonstrate mediates helminth killing through L-arginine depletion. These studies indicate that recruited monocytes are selectively programmed in the pulmonary environment to express AM markers and an anti-helminth phenotype.

Intestinal epithelial tuft cell induction is negated by a murine helminth and its secreted products.

Helminth parasites are adept manipulators of the immune system, using multiple strategies to evade the host type 2 response. In the intestinal niche, the epithelium is crucial for initiating type 2 immunity via tuft cells, which together with goblet cells expand dramatically in response to the type 2 cytokines IL-4 and IL-13. However, it is not known whether helminths modulate these epithelial cell populations. In vitro, using small intestinal organoids, we found that excretory/secretory products (HpES) from Heligmosomoides polygyrus blocked the effects of IL-4/13, inhibiting tuft and goblet cell gene expression and expansion, and inducing spheroid growth characteristic of fetal epithelium and homeostatic repair. Similar outcomes were seen in organoids exposed to parasite larvae. In vivo, H. polygyrus infection inhibited tuft cell responses to heterologous Nippostrongylus brasiliensis infection or succinate, and HpES also reduced succinate-stimulated tuft cell expansion. Our results demonstrate that helminth parasites reshape their intestinal environment in a novel strategy for undermining the host protective response.

Loss of protein tyrosine phosphatase non-receptor type 2 reduces IL-4-driven alternative macrophage activation.

Macrophages are a heterogeneous population of innate immune cells that are often divided into two major subsets: classically activated, typically pro-inflammatory (M1) macrophages that mediate host defense, and alternatively activated, tolerance-inducing (M2) macrophages that exert homeostatic and tissue-regenerative functions. Disturbed macrophage function/differentiation results either in inadequate, excessive immune activation or in a failure to induce efficient protective immune responses against pathogens. Loss-of-function variants in protein tyrosine phosphatase non-receptor type 2 (PTPN2) are associated with chronic inflammatory disorders, but the effect of macrophage-intrinsic PTPN2 loss is still poorly understood. Here we report that PTPN2-deficient macrophages fail to acquire an alternatively activated/M2 phenotype. This was the consequence of reduced IL-6 receptor expression and a failure to induce IL-4 receptor in response to IL-6, resulting in an inability to respond to the key M2-inducing cytokine IL-4. Ultimately, failure to adequately respond to IL-6 and IL-4 resulted in increased levels of M1 macrophage marker expression in vitro and exacerbated lung inflammation upon infection with Nippostrongylus brasiliensis in vivo. These results demonstrate that PTPN2 loss interferes with the ability of macrophages to adequately respond to inflammatory stimuli and might explain the increased susceptibility of PTPN2 loss-of-function carriers to developing inflammatory diseases.

SREBP1-induced fatty acid synthesis depletes macrophages antioxidant defences to promote their alternative activation.

Macrophages exhibit a spectrum of activation states ranging from classical to alternative activation1. Alternatively, activated macrophages are involved in diverse pathophysiological processes such as confining tissue parasites2, improving insulin sensitivity3 or promoting an immune-tolerant microenvironment that facilitates tumour growth and metastasis4. Recently, the metabolic regulation of macrophage function has come into focus as both the classical and alternative activation programmes require specific regulated metabolic reprogramming5. While most of the studies regarding immunometabolism have focussed on the catabolic pathways activated to provide energy, little is known about the anabolic pathways mediating macrophage alternative activation. In this study, we show that the anabolic transcription factor sterol regulatory element binding protein 1 (SREBP1) is activated in response to the canonical T helper 2 cell cytokine interleukin-4 to trigger the de novo lipogenesis (DNL) programme, as a necessary step for macrophage alternative activation. Mechanistically, DNL consumes NADPH, partitioning it away from cellular antioxidant defences and raising reactive oxygen species levels. Reactive oxygen species serves as a second messenger, signalling sufficient DNL, and promoting macrophage alternative activation. The pathophysiological relevance of this mechanism is validated by showing that SREBP1/DNL is essential for macrophage alternative activation in vivo in a helminth infection model.

Tumor suppressor p53 regulates intestinal type 2 immunity.

The role of p53 in tumor suppression has been extensively studied and well-established. However, the role of p53 in parasitic infections and the intestinal type 2 immunity is unclear. Here, we report that p53 is crucial for intestinal type 2 immunity in response to the infection of parasites, such as Tritrichomonas muris and Nippostrongylus brasiliensis. Mechanistically, p53 plays a critical role in the activation of the tuft cell-IL-25-type 2 innate lymphoid cell circuit, partly via transcriptional regulation of Lrmp in tuft cells. Lrmp modulates Ca2+ influx and IL-25 release, which are critical triggers of type 2 innate lymphoid cell response. Our results thus reveal a previously unrecognized function of p53 in regulating intestinal type 2 immunity to protect against parasitic infections, highlighting the role of p53 as a guardian of immune integrity.

Mapping Rora expression in resting and activated CD4+ T cells.

The transcription factor Rora has been shown to be important for the development of ILC2 and the regulation of ILC3, macrophages and Treg cells. Here we investigate the role of Rora across CD4+ T cells in general, but with an emphasis on Th2 cells, both in vitro as well as in the context of several in vivo type 2 infection models. We dissect the function of Rora using overexpression and a CD4-conditional Rora-knockout mouse, as well as a RORA-reporter mouse. We establish the importance of Rora in CD4+ T cells for controlling lung inflammation induced by Nippostrongylus brasiliensis infection, and have measured the effect on downstream genes using RNA-seq. Using a systematic stimulation screen of CD4+ T cells, coupled with RNA-seq, we identify upstream regulators of Rora, most importantly IL-33 and CCL7. Our data suggest that Rora is a negative regulator of the immune system, possibly through several downstream pathways, and is under control of the local microenvironment.

The deubiquitinase CYLD controls protective immunity against helminth infection by regulation of Treg cell plasticity.

BACKGROUND: Type 2 immunity can be modulated by regulatory T (Treg) cell activity. It has been suggested that the deubiquitinase cylindromatosis (CYLD) plays a role in the development or function of Treg cells, implying that it could be important for normal protective immunity, where type 2 responses are prevalent. OBJECTIVE: We sought to investigate the role of CYLD in Treg cell function and TH2 cell immune responses under steady-state conditions and during helminth infection. METHODS: Foxp3-restricted CYLD conditional knockout (KO) mice were examined in mouse models of allergen-induced airway inflammation and Nippostrongylus brasiliensis infection. We performed multiplex magnetic bead assays, flow cytometry, and quantitative PCR to understand how a lack of CYLD affected cytokine production, homing, and suppression in Treg cells. Target genes regulated by CYLD were identified and validated by microarray analysis, coimmunoprecipitation, short hairpin RNA knockdown, and transfection assays. RESULTS: Treg cell-specific CYLD KO mice showed severe spontaneous pulmonary inflammation with increased migration of Treg cells into the lung. CYLD-deficient Treg cells furthermore produced high levels of IL-4 and failed to suppress allergen-induced lung inflammation. Supporting this, the conditional KO mice displayed enhanced protection against N brasiliensis infection by contributing to type 2 immunity. Treg cell conversion into IL-4-producing cells was due to augmented mitogen-activated protein kinase and nuclear factor κB signaling. Moreover, Scinderin, a member of the actin-binding gelsolin family, was highly upregulated in CYLD-deficient Treg cells, and controlled IL-4 production through forming complexes with mitogen-activated protein kinase kinase/extracellular receptor kinase. Correspondingly, both excessive IL-4 production in vivo and the protective role of CYLD-deficient Treg cells against N brasiliensis were reversed by Scinderin ablation. CONCLUSIONS: Our findings indicate that CYLD controls type 2 immune responses by regulating Treg cell conversion into TH2 cell-like effector cells, which potentiates parasite resistance.

Cellular context of IL-33 expression dictates impact on anti-helminth immunity.

Interleukin-33 (IL-33) is a pleiotropic cytokine that can promote type 2 inflammation but also drives immunoregulation through Foxp3+Treg expansion. How IL-33 is exported from cells to serve this dual role in immunosuppression and inflammation remains unclear. Here, we demonstrate that the biological consequences of IL-33 activity are dictated by its cellular source. Whereas IL-33 derived from epithelial cells stimulates group 2 innate lymphoid cell (ILC2)-driven type 2 immunity and parasite clearance, we report that IL-33 derived from myeloid antigen-presenting cells (APCs) suppresses host-protective inflammatory responses. Conditional deletion of IL-33 in CD11c-expressing cells resulted in lowered numbers of intestinal Foxp3+Treg cells that express the transcription factor GATA3 and the IL-33 receptor ST2, causing elevated IL-5 and IL-13 production and accelerated anti-helminth immunity. We demonstrate that cell-intrinsic IL-33 promoted mouse dendritic cells (DCs) to express the pore-forming protein perforin-2, which may function as a conduit on the plasma membrane facilitating IL-33 export. Lack of perforin-2 in DCs blocked the proliferative expansion of the ST2+Foxp3+Treg subset. We propose that perforin-2 can provide a plasma membrane conduit in DCs that promotes the export of IL-33, contributing to mucosal immunoregulation under steady-state and infectious conditions.

[Polarization of human acute monocytic leukemia THP-1 cells-derived macprophages induced by Nippostrongylus brasiliensis proteins in vitro].

OBJECTIVE: To investigate the polarization of human acute monocytic leukemia THP-1 cells-derived macrophages induced by Nippostrongylus brasiliensis proteins in vitro, so as to provide insights into the elucidation of the mechanisms underlying host immune responses to hookworm infections. METHODS: The in-vitro culture of N. brasiliensis was established and maintained in the laboratory, and the third- (L3) and fifth-stage larvae (L5) were collected under a sterile condition for preparation of L3 and L5 proteins. The in-vitro culture of THP-1 cells was established, stimulated with 500 ng/mL PMA to yield M0 macrophages that were adherent to the plate wall. The LPS + IFN-γ group, IL-4 + IL-13 group, L3 protein group and L5 protein group were given stimulation with 500 ng/mL LPS plus 100 ng/mL IFN-γ, IL-4 and IL-13 (both 100 ng/mL), L3 protein (5 mg/mL) and L5 protein (5 mg/mL), respectively, while the negative control group was given no stimulation. The cell morphology was observed using microscopy, the mRNA expression of M1/M2 macrophages-specific genes was quantified using a quantitative real-time PCR (qPCR) assay, and the surface markers of M1/M2 macrophages were detected using flow cytometry, while the levels of cytokines secreted by M1/M2 macrophages were measured using enzyme-linked immunosorbent assay (ELISA) following stimulations, so as to examine the polarization of THP-1-derived macrophages induced by N. brasiliensis proteins in vitro. RESULTS: Following stimulation with PMA, THP-1 cells appeared wall-adherent M0 macrophages, and polarized to typical M1 macrophages following stimulation with LPS + IFN-γ, and typical M2 macrophages following stimulation with IL-4 + IL-13, IL-3 protein or L5 protein. There was a significant difference in the proportion of M1 macrophages among the negative control group, the LPS + IFN-γ group, the IL-4 + IL-13 group, the L3 protein group and the L5 protein group (χ2 = 3 721.00, P < 0.001), with the highest proportion detected in the LPS + IFN-γ group, and there was also a significant difference in the proportion of M2 macrophages among groups (χ2 = 105.43, P < 0.001). There were significant differences among groups in terms of the mRNA expression of CCL2 (F = 191.95, P < 0.001), TNF-α (F = 129.95, P < 0.001), IL-12b (F = 82.89, P < 0.001), PPARγ (F = 11.30, P < 0.001), IL-10 (F = 9.51, P < 0.001) and Mrc1 genes (F = 12.35, P < 0.001). In addition, there were significant differences in the proportion of positive CD86 and CD206 expression among groups (χ2 = 24 004.33 and 832.50, P < 0.001). Higher IL-1ß and TNF-α levels were measured in the LPS + IFN-γ group than in the IL-4 + IL-13 group, the L3 protein group and the L5 protein group (P < 0.001), and greater TGF-ß1 and IL-10 levels were seen in the IL-4 + IL-13 group, the L3 protein group and the L5 protein group than in the negative control group and the LPS + IFN-γ group (P < 0.05). CONCLUSIONS: Both L3 and L5 proteins of N. brasiliensis may induce the polarization of THP-1-derived macrophages to M2 type in vitro.

Tuft-Cell-Derived Leukotrienes Drive Rapid Anti-helminth Immunity in the Small Intestine but Are Dispensable for Anti-protist Immunity.

Helminths, allergens, and certain protists induce type 2 immune responses, but the underlying mechanisms of immune activation remain poorly understood. In the small intestine, chemosensing by epithelial tuft cells results in the activation of group 2 innate lymphoid cells (ILC2s), which subsequently drive increased tuft cell frequency. This feedforward circuit is essential for intestinal remodeling and helminth clearance. ILC2 activation requires tuft-cell-derived interleukin-25 (IL-25), but whether additional signals regulate the circuit is unclear. Here, we show that tuft cells secrete cysteinyl leukotrienes (cysLTs) to rapidly activate type 2 immunity following chemosensing of helminth infection. CysLTs cooperate with IL-25 to activate ILC2s, and tuft-cell-specific ablation of leukotriene synthesis attenuates type 2 immunity and delays helminth clearance. Conversely, cysLTs are dispensable for the tuft cell response induced by intestinal protists. Our findings identify an additional tuft cell effector function and suggest context-specific regulation of tuft-ILC2 circuits within the small intestine.

House dust mite drives proinflammatory eicosanoid reprogramming and macrophage effector functions.

BACKGROUND: Eicosanoid lipid mediators play key roles in type 2 immune responses, for example in allergy and asthma. Macrophages represent major producers of eicosanoids and they are key effector cells of type 2 immunity. We aimed to comprehensively track eicosanoid profiles during type 2 immune responses to house dust mite (HDM) or helminth infection and to identify mechanisms and functions of eicosanoid reprogramming in human macrophages. METHODS: We established an LC-MS/MS workflow for the quantification of 52 oxylipins to analyze mediator profiles in human monocyte-derived macrophages (MDM) stimulated with HDM and during allergic airway inflammation (AAI) or nematode infection in mice. Expression of eicosanoid enzymes was studied by qPCR and western blot and cytokine production was assessed by multiplex assays. RESULTS: Short (24 h) exposure of alveolar-like MDM (aMDM) to HDM suppressed 5-LOX expression and product formation, while triggering prostanoid (thromboxane and prostaglandin D2 and E2 ) production. This eicosanoid reprogramming was p38-dependent, but dectin-2-independent. HDM also induced proinflammatory cytokine production, but reduced granulocyte recruitment by aMDM. In contrast, high levels of cysteinyl leukotrienes (cysLTs) and 12-/15-LOX metabolites were produced in the airways during AAI or nematode infection in mice. CONCLUSION: Our findings show that a short exposure to allergens as well as ongoing type 2 immune responses are characterized by a fundamental reprogramming of the lipid mediator metabolism with macrophages representing particularly plastic responder cells. Targeting mediator reprogramming in airway macrophages may represent a viable approach to prevent pathogenic lipid mediator profiles in allergy or asthma.

Intestinal helminth infection promotes IL-5- and CD4+ T cell-dependent immunity in the lung against migrating parasites.

The ability of helminths to manipulate the immune system of their hosts to ensure their own survival is often credited with affecting responses to other pathogens. We undertook co-infection experiments in mice to determine how infection with the intestinal helminth Heligmosomoides polygyrus affected the parasitological, immunological and physiological outcomes of a primary infection with a distinct species of helminth; the lung migratory parasite Nippostrongylus brasiliensis. We found that migrating N. brasiliensis larvae were killed in the lungs of H. polygyrus-infected mice by a process involving IL-33-activated CD4+ T cells that released IL-5 and recruited activated eosinophils. The lung pathology normally associated with N. brasiliensis larval migration was also reduced. Importantly, lung immunity remained intact in mice cleared of prior H. polygyrus infection and also occurred during infection with another entirely enteric helminth, Trichuris muris. This study identifies a cross-mucosal immune mechanism by which intestinal helminths may protect their hosts against co-infection by a different parasite at a distal site, via circulation of activated CD4+ T cells that can be triggered to release effector cytokines and mount inflammatory responses by tissue damage-associated alarmins, such as IL-33.

Selective expression of constitutively activated STAT6 in intestinal epithelial cells promotes differentiation of secretory cells and protection against helminths.

Intestinal epithelial cells (IECs) constitute an important barrier between host and pathogen. Immune mechanisms that provide protection against gastrointestinal helminths often require IL-4Rα-induced activation of STAT6-regulated genes in IECs. However, it is not known whether STAT6 activation in IECs enhances protective immunity against helminths. Furthermore, the regulation of proliferation and differentiation processes of the intestinal epithelium by IEC-intrinsic STAT6 signaling remains unclear. To address these questions, we generated mice with specific expression of a constitutively active version of STAT6 in IECs. These VillinCre_STAT6vt mice show accumulation of secretory IECs, increased proliferation of IECs and lengthening of the small intestine. They rapidly expelled Nippostrongylus brasiliensis worms even in the absence of T cells. Furthermore, primary infection with Heligmosomoides polygyrus resulted in larval trapping in the submucosa and the fecundity of adult worms was severely impaired. Our results reveal an important IEC-intrinsic role of STAT6-regulated genes for intestinal homeostasis and protective immunity against helminths.

Macrophages promote epithelial proliferation following infectious and non-infectious lung injury through a Trefoil factor 2-dependent mechanism.

Coordinated efforts between macrophages and epithelia are considered essential for wound healing, but the macrophage-derived molecules responsible for repair are poorly defined. This work demonstrates that lung macrophages rely upon Trefoil factor 2 to promote epithelial proliferation following damage caused by sterile wounding, Nippostrongylus brasiliensis or Bleomycin sulfate. Unexpectedly, the presence of T, B, or ILC populations was not essential for macrophage-driven repair. Instead, conditional deletion of TFF2 in myeloid-restricted CD11cCre TFF2 flox mice exacerbated lung pathology and reduced the proliferative expansion of CD45- EpCAM+ pro-SPC+ alveolar type 2 cells. TFF2 deficient macrophages had reduced expression of the Wnt genes Wnt4 and Wnt16 and reconstitution of hookworm-infected CD11cCre TFF2flox mice with rWnt4 and rWnt16 restored the proliferative defect in lung epithelia post-injury. These data reveal a previously unrecognized mechanism wherein lung myeloid phagocytes utilize a TFF2/Wnt axis as a mechanism that drives epithelial proliferation following lung injury.