ILC Subsets Research Articles

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

IntroductionAscaris 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.MethodsNon-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.ResultsNo 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.DiscussionAscaris infection is associated with increased expression of ILC2 activation markers and TPSAB1, which may contribute to the type-2 response.

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.

Bimin Kang ameliorates the minimal persistent inflammation in allergic rhinitis by reducing BCL11B expression and regulating ILC2 plasticity

Ethnopharmacological relevanceMinimal persistent inflammation (MPI) is a major contributor to the recurrence of allergic rhinitis (AR). The traditional Chinese herbal medicine known as Bimin Kang Mixture (BMK) have been used in clinics for decades to treat AR, which can relieve AR symptoms, reduce inflammatory response and improve immune function. However, its mechanism in controlling MPI is still unclear. Aim of the studyThis study aims to assess the therapeutic effect of BMK on MPI, and elaborate the mechanism involved in BMK intervention in BCL11B regulation of type 2 innate lymphoid cell (ILC2) plasticity in the treatment of MPI. Material and methodsThe effect of BMK (9.1 ml/kg) and Loratadine (15.15 mg/kg) on MPI was evaluated based on symptoms, pathological staining, and ELISA assays. RT-qPCR and flow cytometry were also employed to assess the expression of BCL11B, IL-12/IL-12Rβ2, and IL-18/IL-18Rα signaling pathways associated with ILC2 plasticity in the airway tissues of MPI mice following BMK intervention. ResultsBMK restored the airway epithelial barrier, and markedly reduced inflammatory cells (eosinophils, neutrophils) infiltration (P < 0.01) and goblet cells hyperplasia (P < 0.05). BCL11B expression positively correlated with the ILC2 proportion in the lungs and nasal mucosa of AR and MPI mice (P < 0.01). BMK downregulated BCL11B expression (P < 0.05) and reduced the proportion of ILC2, ILC3 and ILC3-like ILC2 subsets (P < 0.05). Moreover, BMK promoted the conversion of ILC2 into an ILC1-like phenotype through IL-12/IL-12Rβ2 and IL-18/IL-18Rα signaling pathways in MPI mice. ConclusionBy downregulating BCL11B expression, BMK regulates ILC2 plasticity and decreases the proportion of ILC2, ILC3, and ILC3-like ILC2 subsets, promoting the conversion of ILC2 to ILC1, thus restoring balance of ILC subsets in airway tissues and control MPI.

Aberrant characteristics of peripheral blood innate lymphoid cells in COPD, independent of smoking history.

Distinguishing asthma and COPD can pose challenges in clinical practice. Increased group 1 innate lymphoid cells (ILC1s) have been found in the lungs and peripheral blood of COPD patients, while asthma is associated with elevated levels of ILC2s. However, it is unclear whether the inflammatory characteristics of ILC1s and ILC2s differ between COPD and asthma. This study aims to compare peripheral blood ILC subsets and their expression of inflammatory markers in COPD patients, asthma patients and controls. The study utilised multi-colour flow cytometry to analyse peripheral blood ILC populations in clinically stable COPD patients (n=38), asthma patients (n=37), and smoking (n=19) and non-smoking (n=16) controls. Proportions of peripheral blood inflammatory CD4+ ILC1s were significantly higher in COPD patients than in asthma. Proportions of CD4- ILC1s were increased in COPD patients compared to asthma patients and smoking controls. Frequencies of CD117- ILC2s were significantly reduced in COPD patients compared with asthma patients. In contrast, the fraction of inflammatory CD45RO+ cells within the CD117- ILC2 population was significantly increased. Principal component analyses showed that combined features of the circulating ILC compartment separated COPD patients from asthma patients and both control groups. Our in-depth characterisation of ILC1 and ILC2 populations in peripheral blood revealed significant differences in their phenotypes between COPD and asthma patients and smoking or non-smoking controls. These findings suggest a role for both ILC subsets in COPD disease pathology, independent of smoking history, and may have implications for patient stratification and therapy development.

Regulatory ILC2-Role of IL-10 Producing ILC2 in Asthma.

Over the past two decades, a growing body of evidence observations have shown group two innate lymphoid cells (ILC2) to be critical drivers of Type 2 (T2) inflammatory responses associated with allergic inflammatory conditions such as asthma. ILC2 releases copious amounts of pro-inflammatory T2 cytokines-interleukin (IL)-4, IL-5, IL-9, and IL-13. This review provides a comprehensive overview of the newly discovered regulatory subtype of ILC2 described in murine and human mucosal tissue and blood. These KLRG1+ILC2 have the capacity to produce the anti-inflammatory cytokine IL-10. Papers compiled in this review were based on queries of PubMed and Google Scholar for articles published from 2000 to 2023 using keywords "IL-10" and "ILC2". Studies with topical relevance to IL-10 production by ILC2 were included. ILC2 responds to microenvironmental cues, including retinoic acid (RA), IL-2, IL-4, IL-10, and IL-33, as well as neuropeptide mediators such as neuromedin-U (NMU), prompting a shift towards IL-10 and away from T2 cytokine production. In contrast, TGF-β attenuates IL-10 production by ILC2. Immune regulation provided by IL-10+ILC2s holds potential significance for the management of T2 inflammatory conditions. The observation of context-specific cues that alter the phenotype of ILC warrants examining characteristics of ILC subsets to determine the extent of plasticity or whether the current classification of ILCs requires refinement.

Paneth cells regulates innate lymphoid cells and B1 cells throughout the body

Abstract Paneth cells are a subset of small intestinal epithelial cells specialized to maintain gastrointestinal homeostasis through production of antimicrobial products and cytokines. The fact that dysbiosis has been associated with several noninfectious pathologies, has solidified the notion that Paneth cells contribute to the general health. However, little is known about Paneth cells beyond their role as regulator of the gut microbiota. Using mice lacking Paneth cells (Sox9 ΔIECmice), we now report that Paneth cells also regulate the composition of immune cell subsets in Gut-Associated Lymphoid Tissues (GALT) and but also in sites distant from the gut. Thus, loss of Paneth cells significantly decreased the number of ILC3s and increased the number of ILC2s in the intestinal lamina propria. Paneth cell deficiency also affected Peyer’s patches. In this regard, Paneth cell deficient mice displayed an increased numbers of Peyer’s patches which were of larger size than Peyer’s patches in control wild-type mice. Furthermore, Peyer’s patches of Paneth cell deficient mice contained increase numbers of IgA +CD19 +B cells and B1a (CD19 +CD5 +) cells. Interestingly, when compared to control wild-type mice, the numbers of B1a cells were found to be also increased in mesenteric lymph nodes of Paneth cell deficient mice, but also at sites distant from the gut including the lungs, and bone marrow. Also, in the lungs there was an increase in ILC2s. Taken together, these findings indicate that Paneth cells play a key role as regulators of innate immune responses throughout the body via regulation of ILC subsets and B1 cells. NIH Grants

IL-1β promotes IL-17A production of ILC3s to aggravate neutrophilic airway inflammation in mice.

IL-17A-producing group 3 innate lymphoid cells (ILC3s) have been found to participate in the development of various phenotypes of asthma, however, little is known about how ILC3s mediate neutrophilic airway inflammation. Elevated IL-1β has been reported in neutrophilic asthma (NA) and IL-1β receptor is highly expressed on lung ILC3s. Therefore, we hypothesize that IL-1β aggravates neutrophilic airway inflammation via provoking IL-17A-producing ILC3s. We sought to determine the pathological roles of the IL-1β-ILC3-IL-17A axis in neutrophilic airway inflammation. Lung ILC subsets were measured in eosinophilic asthma (ovalbumin [OVA]/Alum) and NA (OVA/lipopolysaccharides [LPS]) murine models. Rag2-/- (lacking adaptive immunity), RORc-/- (lacking transcription factor RORγt), Rag2-/- RORc-/- (lacking adaptive immunity and ILC3s), and ILCs depletion mice were used to verify the roles of ILC3s in neutrophilic airway inflammation by measurement of CXCL-1, IL-17A, IL-22 and neutrophil counts in bronchoalveolar lavage fluid (BALF), detection of Muc5ac in lung tissues, and quantification of IL-17A-producing ILC3s after treatment of anti-IL-17A or recombinant IL-1β (rIL-1β) and its monoclonal antibody. NLRP3, Caspase 1 and their induction of IL-1β were detected in lung tissues of OVA/LPS-induced mice. The OVA/LPS model was characterized by an enrichment of airway neutrophilia, lung RORγt+ ILC3s and Th17 cytokines (IL-17A and IL-22) and neutrophilic chemokine C-X-C motif (chemokine) ligand 1 (CXCL-1), compared to the phenotypic features of airway eosinophilia, GATA3+ ILC2s and type-2 cytokines in OVA/Alum model. The concentration of CXCL-1 and neutrophil counts in BALF were decreased by anti-IL-17A. RORγt deficiency led to a decrease in IL-17A and CXCL-1 levels and neutrophil counts in BALF. ILC depletion in Rag2-/- mice ameliorated OVA/LPS-induced IL-17A, IL-22, CXCL-1 and airway neutrophil counts. IL-17A-producing ILCs and BALF neutrophil counts were significantly lower in Rag2-/- RORc-/- mice than those in Rag2-/- mice. IL-1β was highly expressed in BALF and bronchial epithelial cells (BECs) in OVA/LPS model, and administration of rIL-1β substantially aggravated airway inflammation and promoted upregulation of RORγt+ and IL-17A-producing lung ILC3s, which were reversed by anti-IL-1β. NLRP3 and Caspase 1 expressions were enhanced by OVA/LPS, and their inhibitors abolished the OVA/LPS-induced IL-1β in BECs. ILC3s play a pathogenic role in the pathogenesis of NA, which is triggered by IL-1β via promoting IL-17A production of lung ILC3s.

Controversial role of ILC3s in intestinal diseases: A novelty perspective on immunotherapy.

ILC3s have been identified as crucial immune regulators that play a role in maintaining host homeostasis and modulating the antitumor response. Emerging evidence supports the idea that LTi cells play an important role in initiating lymphoid tissue development, while other ILC3s can promote host defense and orchestrate adaptive immunity, mainly through the secretion of specific cytokines and crosstalk with other immune cells or tissues. Additionally, dysregulation of ILC3-mediated overexpression of cytokines, changes in subset abundance, and conversion toward other ILC subsets are closely linked with the occurrence of tumors and inflammatory diseases. Regulation of ILC3 cytokines, ILC conversion and LTi-induced TLSs may be a novel strategy for treating tumors and intestinal or extraintestinal inflammatory diseases. Herein, we discuss the development of ILCs, the biology of ILC3s, ILC plasticity, the correlation of ILC3s and adaptive immunity, crosstalk with the intestinal microenvironment, controversial roles of ILC3s in intestinal diseases and potential applications for treatment.

Immune subset-committed proliferating cells populate the human foetal intestine throughout the second trimester of gestation

The intestine represents the largest immune compartment in the human body, yet its development and organisation during human foetal development is largely unknown. Here we show the immune subset composition of this organ during development, by longitudinal spectral flow cytometry analysis of human foetal intestinal samples between 14 and 22 weeks of gestation. At 14 weeks, the foetal intestine is mainly populated by myeloid cells and three distinct CD3–CD7+ ILC, followed by rapid appearance of adaptive CD4+, CD8+ T and B cell subsets. Imaging mass cytometry identifies lymphoid follicles from week 16 onwards in a villus-like structure covered by epithelium and confirms the presence of Ki-67+ cells in situ within all CD3–CD7+ ILC, T, B and myeloid cell subsets. Foetal intestinal lymphoid subsets are capable of spontaneous proliferation in vitro. IL-7 mRNA is detected within both the lamina propria and the epithelium and IL-7 enhances proliferation of several subsets in vitro. Overall, these observations demonstrate the presence of immune subset-committed cells capable of local proliferation in the developing human foetal intestine, likely contributing to the development and growth of organized immune structures throughout most of the 2nd trimester, which might influence microbial colonization upon birth.

Assessing the Impact of Persistent HIV Infection on Innate Lymphoid Cells Using InVitro Models.

Pathogens that persist in their host induce immune dysfunctions even in the absence of detectable replication. To better understand the phenotypic and functional changes that persistent infections induce in sentinel innate immune cells, we developed human PBMC-based HIV models of persistent infection. Autologous nonactivated PBMCs were cocultured with chronically infected, acutely infected, or uninfected cells and were then analyzed by unsupervised high-dimensional flow cytometry. Using this approach, we identified prevalent patterns of innate immune dysfunctions associated with persistent HIV infections that at least in part mirror immune dysfunctions observed in patients. In one or more models of chronic infection, bystander CD16+ NK cells expressing markers of activation, such as CD94, CD45RO, CD62L, CD69, CD25, and immune checkpoints PD1, Tim3, TIGIT, NKG2A and Lag3, were significantly reduced. Conversely, helper ILC subsets expressing PDL1/PDL2 were significantly enriched in chronic infection compared with either uninfected or acute infection, suggesting that chronic HIV-1 infection was associated with an inhibitory environment for bystander ILC and NK subsets. The cell-based models of persistent infection that we describe here provide versatile tools to explore the molecular mechanisms of these immune dysfunctions and unveil the contribution of innate immunity in sustaining pathogen persistence.

PLZF restricts intestinal ILC3 function in gut defense.

Group 3 innate lymphoid cells (ILC3s) play important roles in maintaining intestinal homeostasis by protecting the host from pathogen infections and tissue inflammation. The transcription factor PLZF (promyelocytic leukemia zinc finger), encoded by zinc finger BTB domain containing 16 (Zbtb16), is highly and transiently expressed in ILC precursors (ILCPs). However, the role of PLZF in regulating ILC3 development and function remains unknown. Here, we show that PLZF was specifically expressed in mature intestinal ILC3s compared with other ILC subsets. PLZF was dispensable for ILC3 development. However, PLZF deficiency in ILC3s resulted in increased innate interleukin-22 (IL-22) secretion and protection against gut infection and inflammation. Mechanistically, PLZF negatively regulated IL-22 expression by ILC3s in a cell-intrinsic manner by binding to the IL-22 promoter region for transcriptional repression. Together, our data suggest that PLZF restricts intestinal ILC3 function to regulate gut immune homeostasis.

Ornithine decarboxylase supports ILC3 responses in infectious and autoimmune colitis through positive regulation of IL-22 transcription

Group 3 innate lymphoid cells (ILC3s) are RORγT+ lymphocytes that are predominately enriched in mucosal tissues and produce IL-22 and IL-17A. They are the innate counterparts of Th17 cells. While Th17 lymphocytes utilize unique metabolic pathways in their differentiation program, it is unknown whether ILC3s make similar metabolic adaptations. We employed single-cell RNA sequencing and metabolomic profiling of intestinal ILC subsets to identify an enrichment of polyamine biosynthesis in ILC3s, converging on the rate-limiting enzyme ornithine decarboxylase (ODC1). In vitro and invivo studies demonstrated that exogenous supplementation with the polyamine putrescine or its biosynthetic substrate, ornithine, enhanced ILC3 production of IL-22. Conditional deletion of ODC1 in ILC3s impaired mouse antibacterial defense against Citrobacter rodentium infection, which was associated with a decrease in anti-microbial peptide production by the intestinal epithelium. Furthermore, in a model of anti-CD40 colitis, deficiency of ODC1 in ILC3s markedly reduced the production of IL-22 and severity of inflammatory colitis. We conclude that ILC3-intrinsic polyamine biosynthesis facilitates efficient defense against enteric pathogens as well as exacerbates autoimmune colitis, thus representing an attractive target to modulate ILC3 function in intestinal disease.

Distinct subsets of innate lymphoid cells in nasal polyp

BackgroundGroup 2 innate lymphoid cells (ILC2s) contribute to the pathogenesis of eosinophilic chronic rhinosinusitis with nasal polyps (CRSwNPs). However, the role of other subsets of ILCs and the differentiation of ILCs in CRSwNPs is not well understood. This study aimed to characterize the ILC subsets and evaluate the differentiation of ILCs from ILC precursors (ILCPs) in NP tissue. MethodsILC subsets and ILCPs were evaluated by flow cytometry in fresh sinonasal mucosa from patients with CRSwNPs and control subjects. Subsets were compared based on clinical variables and immunological features of the patients. Sorted ILCPs (Lin−CD127+CD117+CD45RA+IL1R1+) were cultured with cytokines. ResultsThe frequency of ILC1s and IFN-γ-producing ILC1s increased in non-eosinophilic NPs, whereas that of ILC2s and IL-5-producing ILC2s increased in eosinophilic NPs, particularly in patients with comorbid asthma. The frequency of ILC1s and IFN-γ-producing ILC1s, and frequency of ILC2s and IL-5-producing ILC2s positively correlated with that of neutrophils and eosinophils, respectively. The proportion of IFN-γ-producing ILC1s positively correlated with clinical severity and levels of IFN-γ and IL-8. The proportion of IL-5-producing ILC2s positively correlated with levels of IL-5, CCL24, and total IgE. ILCPs were identified in NP tissue and differentiated into IFN-γ-producing or IL-5-producing ILCs in response to increased IL-12 and IL-18 or IL-25 and IL-33 in non-eosinophilic NPs and eosinophilic NPs, respectively. ConclusionsILC1s and ILC2s may be associated with neutrophilic and eosinophilic inflammation in CRSwNPs, respectively. In addition, ILCPs located in the sinus mucosa could differentiate into IFN-γ- or IL-5-producing cells in response to local cytokine stimuli.

Gene signatures for intestinal and peripheral innate lymphoid cells in pigs reveal tissue-specific imprinting and similarities to human cells via single-cell RNA sequencing

Abstract Intestinal innate lymphoid cells (iILCs) impact intestinal health outcomes, but study of iILCs in humans is limited. Human peripheral ILCs (pILCs) are easily obtained but may vary substantially from iILCs, thus requiring comparison of iILCs and pILCs to determine applicability of pILCs as surrogates to study iILC function. Pigs have anatomic, physiological, nutritional, and immune similarities to humans that are lacking in rodent models, making pigs a relevant biomedical model; however, ILCs are poorly defined in pigs. Single-cell RNA sequencing was performed to compare porcine iILCs to pILCs and determine potential similarities of porcine to human ILCs. Porcine pILCs matched porcine natural killer (NK) cell descriptions, while iILCs were annotated as group 1 and group 3 ILCs. Gene modules obtained independent of cell annotations were distilled to core signatures of genes most highly specific to pILCs, pan-iILCs, group 1 iILCs, and group 3 iILCs. The pILC signature included conventional NK cell genes, while the group 3 iILC signature included genes associated with type 3 immunity. Pan-iILC and group 1 iILC signatures included genes associated with tissue residency, cell activation, and metabolism, indicating tissue-specific, activation-associated imprinting. Gene profiles were used to develop in situ iILC detection methods, establishing group 1 iILCs were intraepithelial, while group 3 iILCs resided in lamina propria/gut-associated lymphoid tissue. Findings indicated iILCs were ILC subsets distinct from pILCs, thus opposing pILCs as surrogates to study iILC dynamics. Moreover, gene profiles and in situ locations of iILCs drew close parallels to human iILCs functions, supporting pigs as a biomedical model for iILC research. Research was supported by appropriated funds from USDA-ARS CRIS 5030-31320-004-00D, an appointment to the Agricultural Research Service (ARS) Research Participation Program administered by the Oak Ridge Institute for Science and Education (ORISE) through an interagency agreement between the U.S. Department of Energy (DOE) and the U.S. Department of Agriculture (USDA). ORISE is managed by ORAU under DOE contract number DE-SC0014664. All opinions expressed in this paper are the authors’ and do not necessarily reflect the policies and views of USDA, ARS, DOE, or ORAU/ORISE. This research used resources provided by the SCINet project of the USDA ARS project number 0500-00093-001-00-D.

Correlation between circulating innate lymphoid cell precursors and thymic function

SummaryThe thymus has a high capacity to support the differentiation of ILCs, especially when E protein transcription factors are ablated. Whether it contributes to the homeostasis of ILC pools in tissues is not clear. Single-cell RNA sequencing analysis shows a substantial amount of ILC precursors in wild type but not athymic nude blood. The precursors express CD3 intracellularly (ic) but not on the surface. The abundance of Lin−CD127+CD62L+icCD3ε+ precursors varies with age, peaking at 2–3 months. These cells can differentiate into various ILC subsets on OP9-DL1 stroma in vitro. In the lung, small intestine, and epidermis, icCD3ε+ cells differentiate into diverse ILC subsets in different tissue environments in steady state. Helminth infection promotes their differentiation toward functional ILC2s. Thus, the thymus appears to play a role in replenishing ILC pools in different peripheral tissues. Because thymic activity is age-dependent, this finding may help explain age-related differences in immune responses.

Evaluation of Innate Lymphoid Cells and Dendritic Cells Following Viral Vector Vaccination.

Recently, we have shown that fate of a vaccine is determined by the cytokine milieu in the innate immune compartment at the early stage of vaccination. Specifically, 24h post-delivery, level of innate lymphoid cell type 2 (ILC2)-derived IL-13/IL-13Rα2 are the master regulators of DC andalso different ILC subsets responsible for modulating the downstream immune outcomes. Here, we provide step-by-step details how to assess different ILC and DC subsets in lung and muscle following intranasal and intramuscular viral vector vaccination, respectively, using multi-color flow cytometry and confocal microscopy.

Innate lymphoid cells exhibited IL-17-expressing phenotype in active tuberculosis disease

BackgroundInnate lymphoid cells (ILCs), as an important group of innate immunity, could respond rapidly to Mycobacterium tuberculosis (Mtb) infection. In this research, we studied the phenotypic changes of circulatory ILCs in active tuberculosis (TB) disease.MethodsWe recruited 40 patients with active Mtb infection (TB group) and 41 healthy subjects (NC group), and collected their clinical information and peripheral blood. Circulating ILCs, ILC subsets, dendritic cells (DCs), macrophages, and the production of cytokines in ILCs were tested by flow cytometry (FCM). Enzyme-linked immunosorbent assay (ELISA) was used to detect plasma IL-23.ResultsCompared with healthy control, total ILCs (0.73% vs. 0.42%, P = 0.0019), ILC1 (0.55% vs. 0.31%, P = 0.0024) and CD117+ ILC2 (0.02% vs. 0.01%, P = 0.0267) were upregulated in TB group. The total IL-17+ lymphocytes were elevated (3.83% vs. 1.76%, P = 0.0006) while the IL-22+ lymphocytes remained unchanged. Within ILC subsets, ILC3, CD117+ ILC2 and ILC1 in TB group all expressed increased IL-17 (15.15% vs. 4.55%, 19.01% vs. 4.57%, 8.79% vs. 3.87%, P < 0.0001) but similar IL-22 comparing with healthy control. TB group had more plasma IL-23 than NC group (7.551 vs. 5.564 pg/mL, P = 0.0557). Plasma IL-23 in TB group was positively correlated to IL-17+ ILC3 (r = 0.4435, P = 0.0141), IL-17+CD117+ ILC2 (r = 0.5385, P = 0.0021) and IL-17+ ILC1(r = 0.3719, P = 0.0430). TB group also had elevated DCs (9.35% vs. 6.49%, P < 0.0001) while macrophages remained unchanged. Within TB group, higher proportion of IL-17+ ILCs was related to severer inflammatory status and poorer clinical condition.ConclusionsIn active TB disease, circulatory ILCs were upregulated and exhibited IL-17-expressing phenotype. This may expand the understanding of immune reaction to Mtb infection.

Cytomegalovirus Infection Impairs the Mobilization of Tissue-Resident Innate Lymphoid Cells into the Peripheral Blood Compartment in Response to Acute Exercise.

Circulating immune cell numbers and phenotypes are impacted by high-intensity acute bouts of exercise and infection history with the latent herpesviruses cytomegalovirus (CMV). In particular, CMV infection history impairs the exercise-induced mobilization of cytotoxic innate lymphoid cells 1 (ILC1) cells, also known as NK cells, in the blood. However, it remains unknown whether exercise and CMV infection modulate the mobilization of traditionally tissue-resident non-cytotoxic ILCs into the peripheral blood compartment. To address this question, 22 healthy individuals with or without CMV (20–35 years—45% CMVpos) completed 30 min of cycling at 70% VO2 max, and detailed phenotypic analysis of circulating ILCs was performed at rest and immediately post-exercise. We show for the first time that a bout of high-intensity exercise is associated with an influx of ILCs that are traditionally regarded as tissue-resident. In addition, this is the first study to highlight that latent CMV infection blunts the exercise-response of total ILCs and progenitor ILCs (ILCPs). These promising data suggest that acute exercise facilitates the circulation of certain ILC subsets, further advocating for the improvements in health seen with exercise by enhancing cellular mobilization and immunosurveillance, while also highlighting the indirect deleterious effects of CMV infection in healthy adults.

Single-cell transcriptomic landscape reveals tumor specific innate lymphoid cells associated with colorectal cancer progression

SummaryInnate lymphoid cells (ILCs) are tissue-resident lymphocytes differing from conventional T lymphocytes in having no antigen-specific receptors. ILCs include natural killer (NK) cells, helper-like ILC1s, ILC2s, and ILC3s, and lymphoid tissue-inducer (LTi) cells. Tumor ILCs are frequently found in various cancers, but their roles in cancer immunity and immunotherapy remain largely unclear. We report here the single-cell characterization of blood and gut helper-like ILC subsets in healthy conditions and in colorectal cancer (CRC). The healthy gut contains ILC1s, ILC3s, and ILC3/NKs, but no ILC2s. Additional tumor-specific ILC1-like and ILC2 subsets were identified in CRC patients. Signaling lymphocytic activation molecule family member 1 (SLAMF1) was found to be selectively expressed on tumor-specific ILCs, and higher levels of SLAMF1+ ILCs were observed in the blood of CRC patients. The SLAMF1-high group of CRC patients had a significantly higher survival rate than the SLAMF1-low group, suggesting that SLAMF1 is an anti-tumor biomarker in CRC.

Transcriptional regulation of type 2 innate lymphoid cells and precursors by interleukin-7 receptor signalling

Abstract Innate lymphoid cells (ILCs) are a rare population of innate immune cells that act as the first line of defense against pathogens. These cells arise from the lymphoid lineage that B and T cells also belong to. Type 2 ILCs (ILC2s) are a subset of ILCs that reside in the lungs, mucosal layers, and skin, and have roles in clearing helminth infections, triggering allergic responses, and promoting lung tissue repair after influenza infections. The functions of ILC2s mirror those of TH2 cells but lack antigen recognition. However, their full development background is still unknown. It is believed that ILC2s develop in the fetal liver and adult bone marrow from common lymphoid progenitors and differentiate into several intermediates including helper ILC precursors. From this, ILC2 progenitors arise and express interleukin-7 (IL-7) receptor with the aid of the transcription factor GATA3. Our lab has found that IL-7 is critical for ILC2 development as mutations to the IL-7 receptor show a reduction in the ILC2 numbers and GATA3 expression. Conversely, overexpression of IL-7 results in the expansion of ILC2s and elevated GATA3 expression. We hypothesize that IL-7 signalling dictates ILC2 development through the transcriptional regulation of lineage determining factors. We aim to identify the transcriptional and epigenetic landscape regulated by IL-7 in ILC2s and their progenitors using single cell RNA sequencing and chromatin immunoprecipitation sequencing. We will also investigate how IL-7 influences airway immune responses generated by ILC2s using flow cytometry and RNA sequencing. This study will increase our understanding of a vital cell population and contribute to the development of therapeutics for allergic asthma and viral infections.