ILC2 Cells Research Articles

Microbiota-derived proteins synergize with IL-23 to drive IL22 production in model type 3 innate lymphoid cells.

Microbiota-induced production of IL-22 by type 3 innate lymphoid cells (ILC3) plays an important role in maintaining intestinal health. Such IL-22 production is driven, in part, by IL-23 produced by gut myeloid cells that have sensed select microbial-derived mediators. The extent to which ILC3 can directly respond to microbial metabolites via IL-22 production is less clear, in part due to the difficulty of isolating and maintaining sufficient numbers of viable ILC3 ex vivo. Hence, we, herein, examined the response of the ILC3 cell line, MNK-3, to microbial metabolites in vitro. We observed that fecal supernatants (FS), by themselves, elicited modest levels of IL-22 and synergized with IL-23 to drive robust IL-22 production assayed by qRT-PCR and ELISA. The IL-22 synergistic activity of FS was not mimicked by an array of candidate microbial metabolites but could be attributed to bacterial proteins. Examining how MNK3 cells exposed to IL-23, FS, both, or neither via RNA-seq and immunoblotting indicated that FS activated MNK-3 cells in a distinct pattern from IL-23: FS activates p-38 MAPK while IL-23 activates STAT3 signaling pathways. Collectively, these studies indicate ILC3 sensing of microbiota proteins promotes IL-22 production suggesting the possibility of manipulating microbiota to increase IL-22 without risk of IL-23-mediated chronic inflammatory diseases.

Tissue-resident NK cells do their own glandscaping

In this issue of JEM, Sparano et al. (https://doi.org/10.1084/jem.20240930) present compelling evidence that salivary gland trNK cells originate from cNK cells and are developmentally distinct from ILC1 cells. Mechanistically, they demonstrate that continuous autocrine TGF-β signaling drives salivary gland tissue residency and works in synergy with IL-15 to enhance Hobit-dependent cytotoxicity.

Artemisitene ameliorates carbon tetrachloride-induced liver fibrosis by inhibiting NLRP3 inflammasome activation and modulating immune responses.

Artemisitene (ATT), an artemisinin (ART) analog retaining the endoperoxide moiety and incorporating an additional α, β-unsaturated carbonyl structure, exhibits enhanced biological activities. However, its therapeutic effects on liver fibrosis remain unclear. In this study, we demonstrated that ATT significantly alleviated liver inflammation and fibrosis induced by carbon tetrachloride (CCL4) in mice. ATT treatment markedly reduced the count of neutrophils in the liver, as well as macrophages in both the liver and spleen. Additionally, the frequencies of Th2 and Th17 cells were significantly lowered, while Th1 cells frequency and the Th1/Th2 index were notably increased. The frequency of ILC2 cells, correlated with ST2 and IL-33 expression levels, was also significantly lowered. Consistently, ATT inhibited NLRP3 inflammasome activation, which was positively associated with AST and ALT levels, and with the count of Neutrophils, macrophages, and ILC2 cells, but negatively correlated with Th1frequeny. Furthermore, liver fibrosis severity showed a significant positive correlation with neutrophil and Th17 cell counts in the liver, and a negative correlation with Th1 cell count and the Th1/Th2 index. Therefore, ATT alleviated CCL4-induced mice liver fibrosis through NLRP3 inflammasome inhibition and immunomodulation.

Berberine ameliorates dextran sulfate sodium -induced colitis through tuft cells and bitter taste signalling

BackgroundInflammatory bowel disease (IBD), a persistent gastrointestinal disease, is featured with impaired gut immunity. Previous studies have demonstrated that tuft cells can regulate the intestinal type 2 immune response by activating downstream ILC2 and Th2 cells and repair gut barrier upon invasion of parasitic helminths, bacteria, protozoans, and enteritis through different chemo-sensing receptors, such as bitter taste receptors. Berberine is a widely used in the treatment of diarrhea in clinic, however the mechanism underlying this effect is not clear. In this study, we aim to explore the relationship between berberine and tuft cells in dextran sulfate sodium (DSS) -induced colitis.ResultsOur data showed that berberine significantly ameliorated DSS-induced colitis and regulating type 2 innate immune lymphocytes (ILC2) and Th2 immune cells via tuft cells in the gut. Furthermore, the effect of berberine on colitis was partially abolished by U73122, a bitter taste receptor inhibitor, suggesting that bitter taste signalling pathway played an important role in the effect of berberine on relieving colitis.ConclusionsBerberine ameliorates dextran sulfate sodium -induced colitis through tuft cells and bitter taste signalling. Our study reveals the unique pharmacological mechanisms of berberine in the context of colitis, laying the foundation for further clinical applications of this compound.

Plasma extracellular vesicles regulate the Functions of Th2 and ILC2 cells via miRNA-150-5p in patients with allergic rhinitis

Allergic rhinitis (AR), a chronic airway inflammation, has witnessed a rising prevalence in recent decades. Recent research indicates that various EVs are released into plasma in allergic airway inflammation, correlating with impaired airway function and severe inflammation. However, the contribution of plasma EVs to AR pathogenesis remains incompletely understood. We isolated plasma EVs using differential ultracentrifugation or size exclusion chromatography (SEC) and obtained differential microRNA (miRNA) expression profiles through miRNA sequencing. Peripheral blood mononuclear cells (PBMCs) were exposed to plasma EVs and miRNA mimics and inhibitors to assess the effect of plasma EVs and the underlying mechanisms. We found that EVs from HC and AR patients exhibited comparable characteristics in terms of concentration, structure, and EV marker expression. AR-EVs significantly enhanced Th2 cell levels and promoted ILC2 differentiation and IL-13+ ILC2 levels compared to HC-EVs. Both HC-EVs and AR-EVs were efficiently internalized by CD4+ T cells and ILCs. miRNA sequencing of AR-EVs revealed unique miRNA signatures implicated in diverse biological processes, among which miR-150-5p, miR-144-3p, miR-10a-5p, and miR-10b-5p were identified as pivotal contributors to AR-EVs’ effects on CD4+ T cells and ILC2s. MiR-150-5p exhibited the most pronounced impact on cell differentiation and was confirmed to be upregulated in AR-EVs by PCR. In total, our study demonstrated that plasma EVs from patients with AR exhibited a pronounced capacity to significantly enhance the differentiation of Th2 cells and ILC2, which was correlated with an elevated expression of miR-150-5p within AR-EVs. These findings contribute to the advancement of our comprehension of EVs in the pathogenesis of AR and hold the potential to unveil novel therapeutic targets for the treatment of AR.

IL-33 protects from recurrent C. difficile infection by restoration of humoral immunity.

Clostridioides difficile infection (CDI) recurs in one of five patients. Monoclonal antibodies targeting the virulence factor TcdB reduce disease recurrence, suggesting that an inadequate anti-TcdB response to CDI leads to recurrence. In patients with CDI, we discovered that IL-33 measured at diagnosis predicts future recurrence, leading us to test the role of IL-33 signaling in the induction of humoral immunity during CDI. Using a mouse recurrence model, IL-33 was demonstrated to be integral for anti-TcdB antibody production. IL-33 acted via ST2+ ILC2 cells, facilitating germinal center T follicular helper (GC-Tfh) cell generation of antibodies. IL-33 protection from reinfection was antibody-dependent, as μMT KO mice and mice treated with anti-CD20 mAb were not protected. These findings demonstrate the critical role of IL-33 in generating humoral immunity to prevent recurrent CDI.

Elevated circulating group-2 innate lymphoid cells expressing activation markers and correlated tryptase AB1 levels in active ascariasis.

Ascaris lumbricoides infection is one of the most common soil-transmitted helminthiasis and IgE response to this helminth may increase the risk of asthma, bronchial hyperreactivity and atopy. There is not enough evidence showing the role of group-2 innate lymphoid cells (ILC2) in the pathogenesis of helminth infections in humans. Here, we aimed to investigate and characterize the influence of Ascaris lumbricoides infection on circulating ILCs in endemically exposed subjects. Non-infected (NI; n=16) and Ascaris-infected (AI; n=16) subjects from an endemic area were included. Two consecutive stool samples from each subject were examined by Kato-Katz to define parasite infection. Antibodies to the ABA-1 antigen of Ascaris and Ascaris extract were measured by ELISA. ILC subsets and their activation markers (CD25, CD69, thymic stromal lymphopoietin receptor (TSLPR) were evaluated in its PBMC by flow cytometry. Proximity extension assay (PEA) was performed to explore plasma proteins associated to infection. No significant differences in the relative or absolute frequencies of total ILCs, ILC1, ILC2 and ILC3 cells were observed regarding the infection status. However, within AI group, IgE-sensitized subjects to ABA-1 had higher frequencies and counts of ILC2 (p<0.05). Frequencies of CD25+, CD69+ and TSLPR+ ILC2 were higher in AI compared to the NI (p<0.01). Additionally, egg burden was positively correlated with CD69+ ILC2 frequencies (r=0.67; p=0.005). Tryptase alpha/beta 1 (TPSAB1), GP6 and several plasma proteins associated with cell growth and granulocyte chemotaxis were highly expressed in the AI group (p<0.05). Interestingly, TPSAB1 levels were positively correlated with ILC2 expressing activation markers frequencies, egg burden and IgE levels against Ascaris. Ascaris infection is associated with increased expression of ILC2 activation markers and TPSAB1, which may contribute to the type-2 response.

Group 2 innate lymphocytes protect the balance between autophagy and apoptosis in cardiomyocytes during sepsis-induced cardiac injury

Group 2 innate lymphocytes (ILC2) have an important role in orchestrating sepsis-induced immune response. However, the impact of LC2 on sepsis-induced cardiac injury is still not fully understood. This study investigated the mechanisms governing ILC2 activation within the cardiac tissue after sepsis. In vivo experiments using wild-type and IL-33 deficient mice indicated that the presence of interleukin (IL)-33, which participates in expanding and activating ILC2 cells, was correlated with higher ILC2 levels (246 ± 34 vs. 66 ± 18, p < 0.01), reduced cardiac dysfunction, and lower markers of cardiac injury. Conversely, IL-33 deficiency led to exacerbated cardiac damage. Additionally, heart ILC2 significantly increased the expression and secretion of IL-5 (2.18 ± 0.34 ng/ml vs. 1.18 ± 0.24 ng/ml, p < 0.05) and IL-13 (10.55 ± 1.13 ng/ml vs. 7.59 ± 1.13 ng/ml, p < 0.05) following sepsis, with this response being mediated by IL-33. Moreover, IL-5 deficient mice exhibited increased cardiac dysfunction and myocardial apoptosis post-sepsis (20.7 ± 4.28% vs. 29.61 ± 4.28%, p < 0.05). Furthermore, in vitro experiments involving co-cultures of ILC2 with mice cardiomyocytes after lipopolysaccharide (LPS) administration suggested that IL-5 derived from ILC2 protects cardiomyocytes from autophagy and apoptosis. These findings imply that IL-33, released in response to sepsis, induces ILC2 activation and IL-5 secretion, orchestrating the equilibrium between autophagy and apoptosis in cardiomyocytes and offering potential therapeutic avenues for mitigating sepsis-induced cardiac injury.

House dust mite allergen directly activates ILC2 cells via the TLR4 signaling pathway in allergic airway diseases

BackgroundUnlike T cells and B cells, the activation process of group 2 innate lymphoid cells (ILC2s) is mainly driven by epithelial cell derived cytokines rather than specific antigen recognition. Whether antigens have a direct role in activating ILC2s remains poorly understood. MethodsFollowing stimulation, type 2 cytokine secretions and cell death were assessed in house dust mite (HDM)-stimulated ILC2s. To investigate the underlying mechanisms, RNA-sequencing (RNA-seq) was performed on HDM-stimulated ILC2s. The validation experiments were done through in vitro stimulation assays and an HDM-induced asthmatic murine model, using specific inhibitors targeting receptor and relevant proteins of signaling pathways. ResultsHDM stimulation increased the secretion of IL-5 and IL-13 cytokines from ILC2s, inhibited apoptosis of ILC2, and promoted the proliferation of ILC2s. As confirmed by RNA-seq, HDM stimulation upregulated genes in ILC2s, including those responsible for type 2 cytokines, ILC2s-specific transcriptional factors, and related receptors. Both toll-like receptor (TLR) 1 and TLR4 were constitutively expressed on ILC2s, however, only TLR4 was predominantly upregulated upon HDM stimulation. TAK242, a specific TLR4 inhibitor, significantly blocked the effect of HDM on ILC2s, in terms of type 2 cytokine secretions and cell death. Using specific inhibitors in pathways, we confirmed that HDM promoted ILC2s activation via TLR4-ERK, p38, and NF-κB signaling pathways. ConclusionsAllergen HDM directly activates ILC2s through TLR4 mediated-ERK/p38/NF-κB signaling pathway. These findings provide new insights into how antigens propagate type 2 immune response via ILC2s, contributing to chronic inflammations in allergic airway diseases.

Is There a Role for Immunostimulant Bacterial Lysates in the Management of Respiratory Tract Infection?

Bacterial Lysates are immunostimulants clinically prescribed for the prevention of respiratory tract infections (RTIs). It has been shown that Bacterial Lysates upregulate the immune system, acting both on innate and adaptive reactions. In fact, there are demonstrations of their efficacy in restoring the integrity and immune function of epithelial barriers, activating ILC3 and dendritic cells with an enhanced Th1 response, and producing serum IgG and serum and salivary IgA specific to the administered bacterial antigens. The activated immune system also protects against other bacteria and viruses due to a trained immunity effect. Most studies show that the number of RTIs and their severity decrease in Bacterial Lysates-pretreated patients, without relevant side effects. The Bacterial Lysates treatment, in addition to reducing the number of RTIs, also prevents the deterioration of the underlying disease (i.e., COPD) induced by repeated infections. Despite these positive data, the most recent meta-analyses evidence the weakness of the studies performed, which are of low quality and have an inadequate number of patients, some of which were non-randomized while others were without a control group or were performed contemporarily in different clinical conditions or with different ages. The high heterogeneity of the studies does not allow us to state Bacterial Lysates' effectiveness in preventing RTIs with sufficient certainty. To completely define their indications, double-blind, placebo-controlled, multicenter, randomized clinical trials should be performed for each product and for each indication. The study population should be adequate for each indication. For this purpose, an adequate run-in phase will be necessary.

Fresh bamboo juice regulates the diversity of intestinal microflora in mice by promoting the function of ILC2 cells to mediate intestinal protection

Background and aimUlcerative colitis (UC) is a growing global health concern, with current treatments facing challenges like drug dependence and side effects. Fresh bamboo juice (FBJ), known for its antimicrobial and potential immune-modulating properties, has shown promise as a natural therapeutic agent. The present study aimed to explore the protective effects of FBJ against colitis and further analyze the changes of gut microbiota composition, metabolite profiles, and underlying immune mechanisms. Materials and MethodsA colitis model in mice was established using DSS to investigate the effectiveness of FBJ. Intestinal tissue and fecal samples were also collected for 16S rRNA gene sequencing and liquid chromatography-mass spectrometry (LC-MS) analysis. Additionally, immunofluorescence and flow cytometry were employed to detect the proliferation and function of group 2 innate lymphoid cells (ILC2). Enzyme-linked immunosorbent assay (ELISA) was used to measure the cytokines secreted by immune cells. ResultsFBJ demonstrated significant therapeutic effects against DSS-induced colitis in mice. At the genus level, the abundance of Bacteroides, Akkermansia and unassigned bacteria in the bamboo juice group increased compared with the DSS group. In contrast, the abundance of Alloprevotella, Lactobacillus, Lachnospiraceae_NK4A136_group and Ruminococcaceae_UCG-014 significantly decreased. FBJ partially restored the balance of gut microbiota, as evidenced by the increased levels of beneficial bacteria. Metabolome analysis revealed significant alterations in fecal metabolites, including 3-Hydroxypyridine, Pyridoxine, SM(d18:1/16:0), and DL-Methionine sulfoxide were remarkably altered. Dysregulation of pathways such as Vitamin B6 metabolism, sphingolipid metabolism, and tyrosine metabolism was observed, which may contribute to protection against colitis. Flow cytometry and immunofluorescence showed a significant reduction in the proportion of ILC2 cells following FBJ treatment in the DSS group (1.82 % v.s. 3.18 %, P < 0.05). ELISA showed that the FBJ group had lower levels of IL-5, IL-6, IL-10, IL-13, IL-33, TNF-α, IFN-γ in intestinal tissue. ConclusionsOur findings demonstrate that FBJ exerts a protective effect against colitis, primarily by modulating the intestinal flora and metabolite profiles in mice with colitis. Furthermore, the observed alterations in bacterial flora and metabolites likely affect ILC2 function and cytokine production, thereby mediating the protective effects against colitis through modulation of the immune system.

Rifaximin ameliorates influenza A virus infection-induced lung barrier damage by regulating gut microbiota

Prior research has indicated that the gut-lung-axis can be influenced by the intestinal microbiota, thereby impacting lung immunity. Rifaximin is a broad-spectrum antibacterial drug that can maintain the homeostasis of intestinal microflora. In this study, we established an influenza A virus (IAV)-infected mice model with or without rifaximin supplementation to investigate whether rifaximin could ameliorate lung injury induced by IAV and explore the molecular mechanism involved. Our results showed that IAV caused significant weight loss and disrupted the structure of the lung and intestine. The analysis results of 16S rRNA and metabolomics indicated a notable reduction in the levels of probiotics Lachnoclostridium, Ruminococcaceae_UCG-013, and tryptophan metabolites in the fecal samples of mice infected with IAV. In contrast, supplementation with 50 mg/kg rifaximin reversed these changes, including promoting the repair of the lung barrier and increasing the abundance of Muribaculum, Papillibacter and tryptophan-related metabolites content in the feces. Additionally, rifaximin treatment increased ILC3 cell numbers, IL-22 level, and the expression of RORγ and STAT-3 protein in the lung. Furthermore, our findings demonstrated that the administration of rifaximin can mitigate damage to the intestinal barrier while enhancing the expression of AHR, IDO-1, and tight junction proteins in the small intestine. Overall, our results provided that rifaximin alleviated the imbalance in gut microbiota homeostasis induced by IAV infection and promoted the production of tryptophan-related metabolites. Tryptophan functions as a signal to facilitate the activation and movement of ILC3 cells from the intestine to the lung through the AHR/STAT3/IL-22 pathway, thereby aiding in the restoration of the barrier.Key points• Rifaximin ameliorated IAV infection-caused lung barrier injury and induced ILC3 cell activation.• Rifaximin alleviated IAV-induced gut dysbiosis and recovered tryptophan metabolism.• Tryptophan mediates rifaximin-induced ILC3 cell activation via the AHR/STAT3/IL-22 pathway.

GPX4 restricts ferroptosis of NKp46+ILC3s to control intestinal inflammation

Group 3 innate lymphoid cells (ILC3s) are essential for both pathogen defense and tissue homeostasis in the intestine. Dysfunction of ILC3s could lead to increased susceptibility to intestinal inflammation. However, the precise mechanisms governing the maintenance of intestinal ILC3s are yet to be fully elucidated. Here, we demonstrated that ferroptosis is vital for regulating the survival of intestinal ILC3. Ferroptosis-related genes, including GPX4, a key regulator of ferroptosis, were found to be upregulated in intestinal mucosal ILC3s from ulcerative colitis patients. Deletion of GPX4 resulted in a decrease in NKp46+ILC3 cell numbers, impaired production of IL-22 and IL-17A, and exacerbated intestinal inflammation in a T cell-independent manner. Our mechanistic studies revealed that GPX4-mediated ferroptosis in NKp46+ILC3 cells was regulated by the LCN2-p38-ATF4-xCT signaling pathway. Mice lacking LCN2 in ILC3s or administration of a p38 pathway inhibitor exhibited similar phenotypes of ILC3 and colitis to those observed in GPX4 conditional knock-out mice. These observations provide novel insights into therapeutic strategies for intestinal inflammation by modulating ILC3 ferroptosis.

Recipient tissue microenvironment determines developmental path of intestinal innate lymphoid progenitors

Innate lymphoid cells (ILCs) are critical in maintaining tissue homeostasis, and during infection and inflammation. Here we identify, by using combinatorial reporter mice, a rare ILC progenitor (ILCP) population, resident to the small intestinal lamina propria (siLP) in adult mice. Transfer of siLP-ILCP into recipients generates group 1 ILCs (including ILC1 and NK cells), ILC2s and ILC3s within the intestinal microenvironment, but almost exclusively group 1 ILCs in the liver, lung and spleen. Single cell gene expression analysis and high dimensional spectral cytometry analysis of the siLP-ILCPs and ILC progeny indicate that the phenotype of the group 1 ILC progeny is also influenced by the tissue microenvironment. Thus, a local pool of siLP-ILCP can contribute to pan-ILC generation in the intestinal microenvironment but has more restricted potential in other tissues, with a greater propensity than bone marrow-derived ILCPs to favour ILC1 and ILC3 production. Therefore, ILCP potential is influenced by both tissue of origin and the microenvironment during development. This may provide additional flexibility during the tuning of immune reactions.

IL-1 Receptor Contributes to the Maintenance of the Intestinal Barrier via IL-22 during Obesity and Metabolic Syndrome in Experimental Model.

Intestinal permeability and bacterial translocation are increased in obesity and metabolic syndrome (MS). ILC3 cells contribute to the integrity of intestinal epithelium by producing IL-22 via IL-1β and IL-23. This study investigates the role of IL-1R1 in inducing ILC3 cells and conferring protection during obesity and MS. For this purpose, C57BL/6 wild-type (WT) and IL-1R1-deficient mice were fed a standard diet (SD) or high-fat diet (HFD) for 16 weeks. Weight and blood glucose levels were monitored, and adipose tissue and blood samples were collected to evaluate obesity and metabolic parameters. The small intestine was collected to assess immunological and junction protein parameters through flow cytometry and RT-PCR, respectively. The intestinal permeability was analyzed using the FITC-dextran assay. The composition of the gut microbiota was also analyzed by qPCR. We found that IL-1R1 deficiency exacerbates MS in HFD-fed mice, increasing body fat and promoting glucose intolerance. A worsening of MS in IL-1R1-deficient mice was associated with a reduction in the ILC3 population in the small intestine. In addition, we found decreased IL-22 expression, increased intestinal permeability and bacterial translocation to the visceral adipose tissue of these mice compared to WT mice. Thus, the IL-1R1 receptor plays a critical role in controlling intestinal homeostasis and obesity-induced MS, possibly through the differentiation or activation of IL-22-secreting ILC3s.

Dynamic regulation of innate lymphoid cell development during ontogeny

The helper-like ILC contains various functional subsets, such as ILC1, ILC2, ILC3 and LTi cells, mediating the immune responses against viruses, parasites, and extracellular bacteria, respectively. Among them, LTi cells are also crucial for the formation of peripheral lymphoid tissues, such as lymph nodes. Our research, along with others’, indicates a high proportion of LTi cells in the fetal ILC pool, which significantly decreases after birth. Conversely, the proportion of non-LTi ILCs increases postnatally, corresponding to the need for LTi cells to mediate lymphoid tissue formation during fetal stages and other ILC subsets to combat diverse pathogen infections postnatally. However, the regulatory mechanism for this transition remains unclear. In this study, we observed a preference for fetal ILC progenitors to differentiate into LTi cells, while postnatal bone marrow ILC progenitors preferentially differentiate into non-LTi ILCs. Particularly, this differentiation shift occurs within the first week after birth in mice. Further analysis revealed that adult ILC progenitors exhibit stronger activation of the Notch signaling pathway compared to fetal counterparts, accompanied by elevated Gata3 expression and decreased Rorc expression, leading to a transition from fetal LTi cell-dominant states to adult non-LTi ILC-dominant states. This study suggests that the body can regulate ILC development by modulating the activation level of the Notch signaling pathway, thereby acquiring different ILC subsets to accommodate the varying demands within the body at different developmental stages.

Context-dependent role of group 3 innate lymphoid cells in mucosal protection.

How group 3 innate lymphoid cells (ILC3s) regulate mucosal protection in the presence of T cells remains poorly understood. Here, we examined ILC3 function in intestinal immunity using ILC3-deficient mice that maintain endogenous T cells, T helper 17 (TH17) cells, and secondary lymphoid organs. ILC3s were dispensable for generation of TH17 and TH22 cell responses to commensal and pathogenic bacteria, and absence of ILC3s did not affect IL-22 production by CD4 T cells before or during infection. However, despite the presence of IL-22-producing T cells, ILC3s and ILC3-derived IL-22 were required for maintaining homeostatic functions of the intestinal epithelium. T cell-sufficient, ILC3-deficient mice were capable of pathogen clearance and survived infection with a low dose of Citrobacter rodentium. However, ILC3s promoted pathogen tolerance at early time points of infection by activating tissue-protective immune pathways. Consequently, ILC3s were indispensable for survival after high-dose infection. Our results demonstrate a context-dependent role for ILC3s in immune-sufficient animals and provide a blueprint for uncoupling of ILC3 and TH17 cell functions.

Type II innate lymphoid cell plasticity contributes to impaired reconstitution after allogeneic hematopoietic stem cell transplantation

Type II innate lymphoid cells (ILC2s) maintain homeostasis and barrier integrity in mucosal tissues. In both mice and humans, ILC2s poorly reconstitute after allogeneic hematopoietic stem cell transplantation (allo-HSCT). Determining the mechanisms involved in their impaired reconstitution could improve transplant outcomes. By integrating single-cell chromatin and transcriptomic analyses of transplanted ILC2s, we identify a previously unreported population of converted ILC1-like cells in the mouse small intestine post-transplant. Exposure of ILC2s to proinflammatory cytokines resulted in a mixed ILC1-ILC2 phenotype but was able to convert only a small population of ILC2s to ILC1s, which were found post-transplant. Whereas ILC2s protected against acute graft-versus-host disease (aGVHD) mediated mortality, infusion of proinflammatory cytokine-exposed ILC2s accelerated aGvHD. Interestingly, murine ILC2 reconstitution post-HSCT is decreased in the presence of alloreactive T cells. Finally, peripheral blood cells from human patients with aGvHD have an altered ILC2-associated chromatin landscape compared to transplanted controls. These data demonstrate that following transplantation ILC2s convert to a pro-pathogenic population with an ILC1-like chromatin state and provide insights into the contribution of ILC plasticity to the impaired reconstitution of ILC2 cells, which is one of several potential mechanisms for the poor reconstitution of these important cells after allo-HSCT.

Supplemental Psyllium Fiber Increases Antimicrobial Proteins via the Tuft Cell-ILC2 Circuit and Type II Immune Response in the Mouse Small Intestine

Dietary fibers regulate intestinal barrier function; however, the precise mechanisms remain unclear. This study investigated the effects of psyllium fibers on antimicrobial protein expression, focusing on the type II immunity and tuft cell-group 2 innate lymphoid cell (ILC2) circuit in the small intestine of the mouse. Supplemental psyllium fiber upregulated antimicrobial proteins, such as small proline-rich protein 2A (SPRR2A) and resistin-like beta (RELMβ), in mouse small intestine, evidently affecting cecal microbiota composition. The psyllium fibers also increased the RNA and protein expression of molecules related to ILC2 and tuft cells, such as IL-13, IL-25, DCLK1, Gfi-1b, SH2 domain-containing protein 3C, and Spi-B. In addition, ILC2 inhibitor (disulfiram) and bitter taste receptor blocker administration reduced psyllium-induced SPRR2A and RELMβ expression. Collectively, psyllium supplementation upregulates antimicrobial proteins such as SPRR2A and RELMß via the type II immune response and tuft cell-ILC2 circuit in the mouse small intestine.

Circulating subpopulations of non-cytotoxic ILCs in diffuse large B-cell lymphoma

AbstractNon-cytotoxic innate lymphoid cells (ILCs) have been added to the list of immune cells that may contribute to the tumor microenvironment. Elevated levels of total ILCs and their subgroups have been reported in peripheral blood and tissue samples from patients with solid tumors, but their frequency in non-Hodgkin lymphomas, particularly diffuse large B-cell lymphoma (DLBCL), has not been clearly established. This study examined frequency and subset distribution in newly diagnosed DLBCL patients (nodal and extra-nodal) and compared it with blood specimens from healthy donors. The percentage of total ILCs (Lin − CD127+) was assessed by flow cytometry, as well as the four ILC subsets, defined as ILC1 (Lin − CD127 + cKit − CRTH2−), ILC2 (Lin − CD127 + cKit+/- CRTH2+), ILCp NCR- (Lin − CD127 + cKit + CRTH2- NKp46-) and NCR + ILC3 (Lin − CD127 + cKit + NKp46+). In the studied group of patients (n = 54), significantly lower levels of circulating total ILCs, ILC1, and ILCp NCR- were observed compared to the control group (n = 43). Similarly, there was a statistically significant decrease in the median frequency of NKp46 + ILC3 cells in lymphoma patients. Analysis of the ILC2 subpopulation showed no significant differences. The correlation of the distribution of individual subpopulations of ILCs with the stage and location of the tumor was also demonstrated. Our results suggest that circulating ILCs are activated and differentiated and/or differentially recruited to the lymph nodes or tumor microenvironment where they may be involved in antitumor defense. However, our observations require confirmation in functional studies.