Plasticity of innate lymphoid cell subsets

AhR ligands from LGG metabolites promote piglet intestinal ILC3 activation and IL-22 secretion to inhibit PEDV infection

In maintaining organismal homeostasis, gut immunity plays a crucial role. The coordination between the microbiota and the immune system through bidirectional interactions regulates the impact of microorganisms on the host. Our research focused on understanding the relationships between substantial changes in jejunal intestinal flora and metabolites and intestinal immunity during porcine epidemic diarrhea virus (PEDV) infection in piglets. We discovered that Lactobacillus rhamnosus GG (LGG) could effectively prevent PEDV infection in piglets. Further investigation revealed that LGG metabolites interact with type 3 innate lymphoid cells (ILC3s) in the jejunum of piglets through the aryl hydrocarbon receptor (AhR). This interaction promotes the activation of ILC3s and the production of interleukin-22 (IL-22). Subsequently, IL-22 facilitates the proliferation of IPEC-J2 cells and activates the STAT3 signaling pathway, thereby preventing PEDV infection. Moreover, the AhR receptor influences various cell types within organoids, including intestinal stem cells (ISCs), Paneth cells, and enterocytes, to promote their growth and development, suggesting that AhR has a broad impact on intestinal health. In conclusion, our study demonstrated the ability of LGG to modulate intestinal immunity and effectively prevent PEDV infection in piglets. These findings highlight the potential application of LGG as a preventive measure against viral infections in livestock.IMPORTANCEWe observed high expression of the AhR receptor on pig and human ILC3s, although its expression was negligible in mouse ILC3s. ILC3s are closely related to the gut microbiota, particularly the secretion of IL-22 stimulated by microbial signals, which plays a crucial regulatory role in intestinal immunity. In our study, we found that metabolites produced by beneficial gut bacteria interact with ILC3s through AhR, thereby maintaining intestinal immune homeostasis in pigs. Moreover, LGG feeding can enhance the activation of ILC3s and promote IL-22 secretion in the intestines of piglets, ultimately preventing PEDV infection.

RIPK3 and caspase-8 interpret cytokine signals to regulate ILC3 survival in the gut

Group 3 innate lymphoid cells (ILC3s) are abundant in the developing or healthy intestine to critically support tissue homeostasis in response to microbial colonization. However, intestinal ILC3s are reduced during chronic infections, colorectal cancer, or inflammatory bowel disease (IBD), and the mechanisms driving these alterations remain poorly understood. Here we employed RNA sequencing of ILC3s from IBD patients and observed a significant upregulation of RIPK3, the central regulator of necroptosis, during intestinal inflammation. This was modeled in mice where we found that intestinal ILC3s express RIPK3, with conventional (c)ILC3s exhibiting high RIPK3 and low levels of pro-survival genes relative to lymphoid tissue inducer (LTi)-like ILC3s. ILC3-specific RIPK3 is promoted by gut microbiota, further upregulated following enteric infection, and dependent upon IL-23R and STAT3 signaling. However, lineage-specific deletion of RIPK3 revealed a redundant role in ILC3 survival, due to a blockade of RIPK3-mediated necroptosis by caspase 8, which was also activated in response to enteric infection. In contrast, lineage-specific deletion of caspase 8 resulted in loss of cILC3s from the healthy intestine and all ILC3 subsets during enteric infection, which increased pathogen burdens and gut inflammation. This function of caspase 8 required catalytic activity induced by TNF or TL1A and was dispensable if RIPK3 was simultaneously deleted. Caspase 8 activation and cell death were associated with increased Fas on ILC3s, and the Fas-FasL pathway was upregulated by cILC3s during enteric infection, which could restrain the abundance of intestinal ILC3s. Collectively, these data reveal that interpretation of key cytokine signals controls ILC3 survival following microbial challenge, and that an imbalance of these pathways, such as in IBD or across ILC3 subsets, provokes depletion of tissue-protective ILC3s from the inflamed intestine.

Development in the Study of Natural Killer Cells for Malignant Peritoneal Mesothelioma Treatment

Malignant peritoneal mesothelioma (MPeM) is a rare primary malignant tumor originating from peritoneal mesothelial cells. Insufficient specificity of the symptoms and their frequent reappearance following surgery make it challenging to diagnose, creating a need for more efficient treatment options. Natural killer cells (NK cells) are part of the innate immune system and are classified as lymphoid cells. Under the regulation of activating and inhibiting receptors, NK cells secrete various cytokines to exert cytotoxic effects and participate in antiforeign body, antiviral, and antitumor activities. This review provides a comprehensive summary of the specific alterations observed in NK cells following MPeM treatment, including changes in cell number, subpopulation distribution, active receptors, and cytotoxicity. In addition, we summarize the impact of various therapeutic interventions, such as chemotherapy, immunotherapy, and targeted therapy, on NK cell function post-MPeM treatment.

Diversity of group 1 innate lymphoid cells in human tissues

Group 1 innate lymphoid cells (ILC1s) are cytotoxic and interferon gamma-producing lymphocytes lacking antigen-specific receptors, which include ILC1s and natural killer (NK) cells. In mice, ILC1s differ from NK cells, as they develop independently of the NK-specifying transcription factor EOMES, while requiring the repressor ZFP683 (ZNF683 in humans) for tissue residency. Here we identify highly variable ILC1 subtypes across tissues through investigation of human ILC1 diversity by single-cell RNA sequencing and flow cytometry. The intestinal epithelium contained abundant mature EOMES- ILC1s expressing PRDM1 rather than ZNF683, alongside a few immature TCF7+PRDM1- ILC1s. Other tissues harbored NK cells expressing ZNF683 and EOMES transcripts; however, EOMES protein content was variable. These ZNF683+ NK cells are tissue-imprinted NK cells phenotypically resembling ILC1s. The tissue ILC1-NK spectrum also encompassed conventional NK cells and NK cells distinguished by PTGDS expression. These findings establish a foundation for evaluating phenotypic and functional changes within the NK-ILC1 spectrum in diseases.

CD146, a therapeutic target involved in cell plasticity

Since its identification as a marker for advanced melanoma in the 1980s, CD146 has been found to have multiple functions in both physiological and pathological processes, including embryonic development, tissue repair and regeneration, tumor progression, fibrosis disease, and inflammations. Subsequent research has revealed that CD146 is involved in various signaling pathways as a receptor or co-receptor in these processes. This correlation between CD146 and multiple diseases has sparked interest in its potential applications in diagnosis, prognosis, and targeted therapy. To better comprehend the versatile roles of CD146, we have summarized its research history and synthesized findings from numerous reports, proposing that cell plasticity serves as the underlying mechanism through which CD146 contributes to development, regeneration, and various diseases. Targeting CD146 would consequently halt cell state shifting during the onset and progression of these related diseases. Therefore, the development of therapy targeting CD146 holds significant practical value.

Stage-specific GATA3 induction promotes ILC2 development after lineage commitment

Group 2 innate lymphoid cells (ILC2s) are a subset of innate lymphocytes that produce type 2 cytokines, including IL-4, IL-5, and IL-13. GATA3 is a critical transcription factor for ILC2 development at multiple stages. However, when and how GATA3 is induced to the levels required for ILC2 development remains unclear. Herein, we identify ILC2-specific GATA3-related tandem super-enhancers (G3SE) that induce high GATA3 in ILC2-committed precursors. G3SE-deficient mice exhibit ILC2 deficiency in the bone marrow, lung, liver, and small intestine with minimal impact on other ILC lineages or Th2 cells. Single-cell RNA-sequencing and subsequent flow cytometry analysis show that GATA3 induction mechanism, which is required for entering the ILC2 stage, is lost in IL-17RB+PD-1- late ILC2-committed precursor stage in G3SE-deficient mice. Cnot6l, part of the CCR4-NOT deadenylase complex, is a possible GATA3 target during ILC2 development. Our findings implicate a stage-specific regulatory mechanism for GATA3 expression during ILC2 development.

Group2 innate lymphoid cells ameliorate renal fibrosis and dysfunction associated with adenine-induced CKD

Renal fibrosis is a common pathway of chronic kidney disease (CKD) progression involving primary kidney injury and kidney diseases. Group 2 innate lymphoid cells (ILC2s) mediate type 2 immune responses irrespective of antigen presentation and play a reno-protective role in kidney injury and disease. In the present study, we observed a decrease in kidney-resident ILC2s in CKD and found that enrichment of ILC2s in the kidney ameliorates renal fibrosis. In CKD kidney, ILC2s preferentially produced IL-13 over IL-5 in response to IL-33 stimulation, regardless of ST2L expression. Moreover, GATA3 expression was decreased in ILC2s, and T-bet+ ILC1s and RORγt+ ILC3s were increased in CKD kidney. Adoptive transfer of kidney ILC2s into adenine-induced CKD model mouse improved renal function and fibrosis. Renal fibroblasts cultured with IL33-activated kidney ILC2s suppressed myofibroblast trans-differentiation through Acta2 and Fn-1 regulation. These results suggest that kidney ILC2s prevent CKD progression via improvement of renal fibrosis. Our findings also suggest that ILC2s may contribute to the development of new therapeutic agents and strategies for tissue fibroses.

Non-allergic eosinophilic inflammation and airway hyperresponsiveness induced by diesel engine exhaust through activating ILCs

RATIONALE

Diesel engine exhaust (DEE) is associated with the development and exacerbation of asthma. Studies have shown that DEE can aggravate allergen-induced eosinophilic inflammation in lung. However, it remains not clear that whether DEE alone could initiate non-allergic eosinophilic inflammation and airway hyperresponsiveness (AHR) through innate lymphoid cells (ILCs) pathway.

OBJECTIVE

This study aims to investigate the airway inflammation and hyperresponsiveness and its relationship with ILC after DEE exposure.

METHOD

Non-sensitized BALB/c mice were exposed in the chamber of diesel exhaust or filtered air for 2, 4, and 6 weeks (4 h/day, 6 days/week). Anti-CD4 mAb or anti-Thy1.2 mAb was administered by intraperitoneal injection to inhibit CD4+T or ILCs respectively. AHR、airway inflammation and ILCs were assessed.

RESULT

DEE exposure induced significantly elevated level of neutrophils, eosinophils, collagen content at 4, 6 weeks. Importantly, the airway AHR was only significant in the 4weeks-DEE exposure group. No difference of the functional proportions of Th2 cells was found between exposure group and control group. The proportions of IL-5+ILC2, IL-17+ILC significantly increased in 2, 4weeks-DEE exposure group. After depletion of CD4+T cells, both the proportion of IL-5+ILC2 and IL-17A ILCs was higher in the 4weeks-DEE exposure group which induced AHR, neutrophilic and eosinophilic inflammation accompanied by the IL-5, IL-17A levels.

CONCLUSION

Diesel engine exhaust alone can imitate asthmatic characteristics in mice model. Lung-resident ILCs are one of the major effectors cells responsible for a mixed Th2/Th17 response and AHR.

Intestinal CXCR6+ ILC3s migrate to the kidney and exacerbate renal fibrosis via IL-23 receptor signaling enhanced by PD-1 expression

Group 3 innate lymphoid cells (ILC3s) regulate inflammation and tissue repair at mucosal sites, but whether these functions pertain to other tissues-like the kidneys-remains unclear. Here, we observed that renal fibrosis in humans was associated with increased ILC3s in the kidneys and blood. In mice, we showed that CXCR6+ ILC3s rapidly migrated from the intestinal mucosa and accumulated in the kidney via CXCL16 released from the injured tubules. Within the fibrotic kidney, ILC3s increased the expression of programmed cell death-1 (PD-1) and subsequent IL-17A production to directly activate myofibroblasts and fibrotic niche formation. ILC3 expression of PD-1 inhibited IL-23R endocytosis and consequently amplified the JAK2/STAT3/RORγt/IL-17A pathway that was essential for the pro-fibrogenic effect of ILC3s. Thus, we reveal a hitherto unrecognized migration pathway of ILC3s from the intestine to the kidney and the PD-1-dependent function of ILC3s in promoting renal fibrosis.

Epigenetic regulation of innate lymphoid cells

Innate lymphoid cells (ILCs) lack antigen-specific receptors and are considered the innate arm of the immune system, phenotypically and functionally mirroring CD4+ helper T cells. ILCs are categorized into groups 1, 2, and 3 based on transcription factors and cytokine expression. ILCs predominantly reside in mucosal tissues and play important roles in regional immune responses. The development and function of ILC subsets are controlled by both transcriptional and epigenetic mechanisms, which have been extensively studied in recent years. Epigenetic regulation refers to inheritable changes in gene expression that occur without affecting DNA sequences. This mainly includes chromatin status, histone modifications, and DNA methylation. In this review, we summarize recent discoveries on epigenetic mechanisms regulating ILC development and function, and how these regulations affect disease progression under pathological conditions. Although the ablation of specific epigenetic regulators can cause global changes in corresponding epigenetic modifications to the chromatin, only partial genes with altered epigenetic modifications change their mRNA expression, resulting in specific outcomes in cell differentiation and function. Therefore, elucidating epigenetic mechanisms underlying the regulation of ILCs will provide potential targets for the diagnosis and treatment of inflammatory diseases.

Group 3 innate lymphoid cells in intestinal health and disease

The gastrointestinal tract is an immunologically rich organ, containing complex cell networks and dense lymphoid structures that safeguard this large absorptive barrier from pathogens, contribute to tissue physiology and support mucosal healing. Simultaneously, the immune system must remain tolerant to innocuous dietary antigens and trillions of normally beneficial microorganisms colonizing the intestine. Indeed, a dysfunctional immune response in the intestine underlies the pathogenesis of numerous local and systemic diseases, including inflammatory bowel disease, food allergy, chronic enteric infections or cancers. Here, we discuss group 3 innate lymphoid cells (ILC3s), which have emerged as orchestrators of tissue physiology, immunity, inflammation, tolerance and malignancy in the gastrointestinal tract. ILC3s are abundant in the developing and healthy intestine but their numbers or function are altered during chronic disease and cancer. The latest studies provide new insights into the mechanisms by which ILC3s fundamentally shape intestinal homeostasis or disease pathophysiology, and often this functional dichotomy depends on context and complex interactions with other cell types or microorganisms. Finally, we consider how this knowledge could be harnessed to improve current treatments or provoke new opportunities for therapeutic intervention to promote gut health.

Epithelial-immune cell crosstalk for intestinal barrier homeostasis

The intestinal barrier is mainly formed by a monolayer of epithelial cells, which forms a physical barrier to protect the gut tissues from external insults and provides a microenvironment for commensal bacteria to colonize while ensuring immune tolerance. Moreover, various immune cells are known to significantly contribute to intestinal barrier function by either directly interacting with epithelial cells or by producing immune mediators. Fulfilling this function of the gut barrier for mucosal homeostasis requires not only the intrinsic regulation of intestinal epithelial cells (IECs) but also constant communication with immune cells and gut microbes. The reciprocal interactions between IECs and immune cells modulate mucosal barrier integrity. Dysregulation of barrier function could lead to dysbiosis, inflammation, and tumorigenesis. In this overview, we provide an update on the characteristics and functions of IECs, and how they integrate their functions with tissue immune cells and gut microbiota to establish gut homeostasis.

NRP1 downregulation correlates with enhanced ILC2 responses during IL-33 challenge

Group 2 innate lymphoid cells (ILC2s) play critical roles in driving the pathogenesis of allergic airway inflammation. The mechanisms underlying the regulation of ILC2s remain to be fully understood. Here, we identified neuropilin-1 (NRP1) as a surface marker of ILC2s in response to IL-33 stimulation. NRP1 was abundantly expressed in ILC2s from lung under steady state, which was significantly reduced upon IL-33 stimulation. ILC2s with high expression of NRP1 (NRP1high) displayed lower response to IL-33, as compared with NRP1low ILC2s. Transcriptional profiling and flow cytometric analysis showed that downregulation of AKT-mTOR signalling participated in the diminished functionality of NRP1high ILC2s. These observations revealed a potential role of NRP1 in ILC2s responses under allergic inflammatory condition.

Implications of innate lymphoid cells in oral diseases

Innate lymphoid cells (ILCs), as newly discovered antigen-independent innate immune cells, respond promptly to stimuli by secreting effector cytokines to exert effector functions similar to those of T cells. ILCs predominantly reside at mucosal sites and play critical roles in defending against infections, maintaining mucosal homeostasis, regulating inflammatory and immune responses, and participating in tumorigenesis. Recently, there has been a growing interest in the role of ILCs in oral diseases. This review outlines the classifications and the major characteristics of ILCs, and then comprehensively expatiates the research on ILCs in oral cancer, primary Sjogren's syndrome, periodontal diseases, oral lichen planus, oral candidiasis, Behcet's disease, and pemphigus vulgaris, aiming at summarising the implications of ILCs in oral diseases and providing new ideas for further research.

Group 1 ILCs: Heterogeneity, plasticity, and transcriptional regulation

Group 1 innate lymphoid cells (ILCs), comprising ILC1s and natural killer cells (NK cells), belong to a large family of developmentally related innate lymphoid cells that lack rearranged antigen-specific receptors. NK cells and ILC1s both require the transcription factor T-bet for lineage commitment but additionally rely on Eomes and Hobit, respectively, for their development and effector maturation programs. Both ILC1s and NK cells are essential for rapid responses against infections and mediate cancer immunity through production of effector cytokines and cytotoxicity mediators. ILC1s are enriched in tissues and hence generally considered tissue resident cells whereas NK cells are often considered circulatory. Despite being deemed different cell types, ILC1s and NK cells share many common features both phenotypically and functionally. Recent studies employing single cell RNA sequencing (scRNA-seq) technology have exposed previously unappreciated heterogeneity in group 1 ILCs and further broaden our understanding of these cells. Findings from these studies imply that ILC1s in different tissues and organs share a common signature but exhibit some unique characteristics, possibly stemming from tissue imprinting. Also, data from recent fate mapping studies employing Hobit, RORγt, and polychromic reporter mice have greatly advanced our understanding of the developmental and effector maturation programs of these cells. In this review, we aim to outline the fundamental traits of mouse group 1 ILCs and explore recent discoveries related to their developmental programs, phenotypic heterogeneity, plasticity, and transcriptional regulation.

Group 3 innate lymphoid cells: A trained Gutkeeper

Group 3 innate lymphoid cells (ILC3s) are tissue-resident immune lymphocytes that critically regulate intestinal homeostasis, organogenesis, and immunity. ILC3s possess the capacity to "sense" the inflammatory environment within tissues, especially in the context of pathogen challenges that imprints durable non-antigen-specific changes in ILC3 function. As such, ILC3s become a new actor in the emerging field of trained innate immunity. Here, we summarize recent discoveries regarding ILC3 responses to bacterial challenges and the role these encounters play in triggering trained innate immunity. We further discuss how signaling events throughout ILC3 ontogeny potentially control the development and function of trained ILC3s. Finally, we highlight the open questions surrounding ILC3 "training" the answers to which may reveal new insights into innate immunity. Understanding the fundamental concepts behind trained innate immunity could potentially lead to the development of new strategies for improving immunity-based modulation therapies for inflammation, infectious diseases, and cancer.

Sex differences orchestrated by androgens at single-cell resolution

Sex differences in mammalian complex traits are prevalent and are intimately associated with androgens1-7. However, a molecular and cellular profile of sex differences and their modulation by androgens is still lacking. Here we constructed a high-dimensional single-cell transcriptomic atlas comprising over 2.3 million cells from 17 tissues in Mus musculus and explored the effects of sex and androgens on the molecular programs and cellular populations. In particular, we found that sex-biased immune gene expression and immune cell populations, such as group 2 innate lymphoid cells, were modulated by androgens. Integration with the UK Biobank dataset revealed potential cellular targets and risk gene enrichment in antigen presentation for sex-biased diseases. This study lays the groundwork for understanding the sex differences orchestrated by androgens and provides important evidence for targeting the androgen pathway as a broad therapeutic strategy for sex-biased diseases.

A Membrane Lipid Signature Unravels the Dynamic Landscape of Group 1 ILCs

In an era where the established lines between cell identities are blurred by intra-lineage plasticity, distinguishing between stable and transitional states becomes imperative. This challenge is particularly pronounced within the Group 1 ILC lineage, where the similarity and plasticity between NK cells and ILC1s obscure their classification and the assignment of their unique contributions to immune regulation. This study exploits the unique property of Asialo-GM1 (AsGM1)-a membrane lipid associated with cytotoxic attributes absent in ILC1s-as a definitive criterion to distinguish between these cells. By prioritizing cytotoxic potential as the cardinal differentiator, our strategic use of the AsGM1 signature achieved precise delineation of NK cells and ILC1s across tissues, validated by RNA-seq analysis. This capability extends beyond steady-state classifications, adeptly capturing the binary classification of NK cells and ILC1s during acute liver injury. By leveraging two established models of NK-to-ILC1 plasticity driven by TGFβ and Toxoplasma gondii , we demonstrate the stability of the AsGM1 signature, which sharply contrasts with the loss of Eomes. This signature identified a spectrum of known and novel NK cell derivatives-ILC1-like entities that bridge traditional binary classifications in aging and infection. The early detection of the AsGM1 signature at the immature NK (iNK) stage, preceding Eomes, and its stability, unaffected by transcriptional reprogramming that typically alters Eomes, position AsGM1 as a unique, site-agnostic marker for fate mapping NK-to-ILC1 plasticity. This provides a powerful tool to explore the expanding heterogeneity within the Group 1 ILC landscape, effectively transcending the ambiguity inherent to the NK-to-ILC1 continuum.

ILC2s: Unraveling the innate immune orchestrators in allergic inflammation

The prevalence rate of allergic diseases including asthma, atopic rhinitis (AR) and atopic dermatitis (AD) has been significantly increasing in recent decades due to environmental changes and social developments. With the study of innate lymphoid cells, the crucial role played by type 2 innate lymphoid cells (ILC2s) have been progressively unveiled in allergic diseases. ILC2s, which are a subset of innate lymphocytes initiate allergic responses. They respond swiftly during the onset of allergic reactions and produce type 2 cytokines, working in conjunction with T helper type 2 (Th2) cells to induce and sustain type 2 immune responses. The role of ILC2s represents an intriguing frontier in immunology; however, the intricate immune mechanisms of ILC2s in allergic responses remain relatively poorly understood. To gain a comphrehensive understanding of the research progress of ILC2, we summarize recent advances in ILC2s biology in pathologic allergic inflammation to inspire novel approaches for managing allergic diseases.

Intestinal Mucosal Immune Barrier: A Powerful Firewall Against Severe Acute Pancreatitis-Associated Acute Lung Injury via the Gut-Lung Axis

The pathogenesis of severe acute pancreatitis-associated acute lung injury (SAP-ALI), which is the leading cause of mortality among hospitalized patients in the intensive care unit, remains incompletely elucidated. The intestinal mucosal immune barrier is a crucial component of the intestinal epithelial barrier, and its aberrant activation contributes to the induction of sustained pro-inflammatory immune responses, paradoxical intercellular communication, and bacterial translocation. In this review, we firstly provide a comprehensive overview of the composition of the intestinal mucosal immune barrier and its pivotal roles in the pathogenesis of SAP-ALI. Secondly, the mechanisms of its crosstalk with gut microbiota, which is called gut-lung axis, and its effect on SAP-ALI were summarized. Finally, a number of drugs that could enhance the intestinal mucosal immune barrier and exhibit potential anti-SAP-ALI activities were presented, including probiotics, glutamine, enteral nutrition, and traditional Chinese medicine (TCM). The aim is to offer a theoretical framework based on the perspective of the intestinal mucosal immune barrier to protect against SAP-ALI.

COPD with elevated sputum group 2 innate lymphoid cells is characterized by severe disease

Rationale

Pulmonary innate immune cells play a central role in the initiation and perpetuation of chronic obstructive pulmonary disease (COPD), however the precise mechanisms that orchestrate the development and severity of COPD are poorly understood.

Objectives

We hypothesized that the recently described family of innate lymphoid cells (ILCs) play an important role in COPD.

Methods

Subjects with COPD and healthy controls were clinically evaluated, and their sputum samples were assessed by flow cytometry. A mouse model of spontaneous COPD [genetically deficient in surfactant protein-D (SP-D -/- )] and ozone (O 3 ) exposure were used to examine the mechanism by which lack of functional SP-D may skew ILC2s to produce IL-17A in combination with IL-5 and IL-13, leading to a mixed inflammatory profile and more severe disease.

Measurements and Main Results

COPD was characterized by poor spirometry, sputum inflammation, and the emergence of sputum GATA3 + ILCs (ILC2s), but not T-bet + ILCs (ILC1s) nor RORγt + ILCs (ILC3s). COPD subjects with elevated sputum ILC2s (the ILC2 high group) had worse spirometry and sputum neutrophilia and eosinophilia than healthy and ILC2 low subjects. This was associated with the presence of dual-positive IL-5 + IL-17A + and IL-13 + IL-17A + ILCs and nonfunctional SP-D in the sputum in ILC2 high subjects. SP-D -/- mice showed spontaneous airway neutrophilia. Lack of SP-D in the mouse lung licensed ILC2s to produce IL-17A, which was dose-dependently inhibited by recombinant SP-D. SP-D -/- mice showed enhanced susceptibility to O 3 -induced airway neutrophilia, which was associated with the emergence of inflammatory IL-13 + IL-17A + ILCs.

Conclusions

We report that the presence of sputum ILC2s predicts the severity of COPD, and unravel a novel pathway of IL-17A plasticity in lung ILC2s, prevented by the immunomodulatory protein SP-D.

Improvement of hepatic innate immunity in chemically-injured livers to develop hepatocarcinoma by a serine type-protease inhibitors enriched extract from Chenopodium quinoa

Food ingredients have critical effects on the maturation and development of the immune system, which innate - lymphoid (ILCs) and myeloid - cells play key roles as important regulators of energy storage and hepatic fat accumulation. Therefore, the objective of this study is to define potential links between a dietary immunonutritional induction of the selective functional differentiation of monocytes-derived macrophages, ILCs and lipid homeostasis in hepatocarcinoma (HCC)-developing mice. Hepatic chemically injured (diethylnitrosamine/thiacetamide) Rag2-/- and Rag2-/-Il2-/- mice were administered with serine-type protease inhibitors (SETIs) obtained from Chenopodium quinoa. Early HCC-driven immunometabolic imbalances (infiltrated macrophages, glucose homeostasis, hepatic lipid profile, ILCs expansion, inflammatory conditions, microbiota) in animals put under a high-fat diet for 2 weeks were assessed. It was also approached the potential of SETIs to cause functional adaptations of the bioenergetics of human macrophage-like cells (hMLCs) in vitro conditioning their capacity to accumulate fat. It is showed that Rag2-/-Il2-/- mice, lacking ILCs, are resistant to the SETIs-induced hepatic macrophages (CD68+F4/80+) activation. Feeding SETIs to Rag2-/- mice, carrying ILCs, promoted the expansion towards ILC3s (CD117+Nkp46+CD56+) and reduced that of ILC2s (CD117+KLRG1+) into livers. In vitro studies demonstrate that hMLCs, challenged to SETIs, develop a similar phenotype of that found in mice and bioenergetic adaptations leading to increased lipolysis. It is concluded that SETIs promote liver macrophage activation and ILCs adaptations to ameliorate HCC-driven immunometabolic imbalances.

People are an organic unity: Gut-lung axis and pneumonia

People are an organic unity. Every organ of our body doesn't exist alone. They are a part of our body and have important connections with other tissues or organs. The gut-lung axis is a typical example. Here, we reviewed the current research progress of the gut-lung axis. The main cross-talk between the intestine and lungs was sorted out, i.e. the specific interaction content contained in the gut-lung axis. We determine a relatively clear concept for the gut-lung axis, that is, the gut-lung axis is a cross-talk that the gut and lungs interact with each other through microorganisms and the immune system to achieve bidirectional regulation. The gut and lungs communicate with each other mainly through the immune system and symbiotic microbes, and these two pathways influence each other. The portal vein system and mesenteric lymphatics are the primary communication channels between the intestine and lungs. We also summarized the effects of pneumonia, including Coronavirus disease 2019 (COVID-19) and Community-Acquired Pneumonia (CAP), on intestinal microbes and immune function through the gut-lung axis, and discussed the mechanism of this effect. Finally, we explored the value of intestinal microbes and the gut-lung axis in the treatment of pneumonia through the effect of intestinal microbes on pneumonia.

Communication between Mast Cells and Group 2 Innate Lymphoid Cells in the Skin

The skin is a dynamic organ with a complex immune network critical for maintaining balance and defending against various pathogens. Different types of cells in the skin, such as mast cells (MCs) and group 2 innate lymphoid cells (ILC2s), contribute to immune regulation and play essential roles in the early immune response to various triggers, including allergens. It is beneficial to dissect cell-to-cell interactions in the skin to elucidate the mechanisms underlying skin immunity. The current manuscript concentrates explicitly on the communication pathways between MCs and ILC2s in the skin, highlighting their ability to regulate immune responses, inflammation, and tissue repair. Furthermore, it discusses how the interactions between MCs and ILC2s play a crucial role in various skin conditions, such as autoimmune diseases, dermatological disorders, and allergic reactions. Understanding the complex interactions between MCs and ILC2s in different skin conditions is crucial to developing targeted treatments for related disorders. The discovery of shared pathways could pave the way for novel therapeutic interventions to restore immunological balance in diseased skin tissues.

Innate lymphoid cells (ILCs) in teleosts against data on ILCs in humans

It is assumed that cells corresponding to innate lymphoid cells (ILCs) in humans, in addition to lymphoid tissue inducer cells (LTi), are also found in teleosts. In this systematic group of organisms, however, they are a poorly understood cell population. In contrast to the data on ILCs in humans, which also remain incomplete despite advanced research, in teleosts, these cells require much more attention. ILCs in teleosts have been presented as cells that may be evolutionary precursors of NK cells or ILCs identified in mammals, including humans. It is a highly heterogeneous group of cells in both humans and fish and their properties, as revealed by studies in humans, are most likely to remain strictly dependent on the location of these cells and the physiological state of the individual from which they originate. They form a bridge between innate and adaptive immunity. The premise of this paper is to review the current knowledge of ILCs in teleosts, taking into account data on similar cells in humans. A review of the knowledge concerning these particular cells, elements of innate immunity mechanisms as equivalent to, or perhaps dominant over, adaptive immunity mechanisms in teleosts, as presented, may inspire the need for further research.

Estriol and commensal microflora strains regulate innate lymphoid cells functional activity in multiple sclerosis

Multiple sclerosis (MS) is an autoimmune neurodegenerative disease in which the immune system attacks myelin basic protein of nerve axons. Recently, there has been growing interest in studying the role of a newly described population of immunity cells - innate lymphoid cells (ILCs) in the pathogenesis of the disease. At the same time, it was found that during pregnancy there is a weakening of Th1-mediated autoimmune pathologies manifestations, including MS. In this work, we studied phenotypic characteristics of ILC in MS patients in comparison with healthy donors after 48 h incubation with pregnancy hormone estriol (E3) and commensal microflora cells. To activate ILC, strains of Ecsherichia coli K12 and Lactobacillus plantarum 8R-A3 were used. ILC phenotype was assessed by flow cytometry using monoclonal antibody staining. It has been established that E3 and bacterial factors are able to regulate the maturation of ILC subtypes and their cytokines in different ways. In general, the studied factors influence the phenotypic changes in ILC cells, leading to the transition from one type to another, both in healthy donors and in MS patients.

In-Depth Proteomic Map of Innate Lymphoid Cells from Healthy Human Skin and Blood

Innate lymphoid cells (ILCs) are essential players in the skin-associated immune system, nevertheless little is known about their proteomes and proteomic diversity. In this study, we describe about 6,600 proteins constitutively expressed by ILC2s and ILC3s from healthy human skin and blood using state-of-the-art proteomics. Although the vast majority of proteins was expressed by both ILC subsets and in both compartments, the skin ILC2s and ILC3s were more distinct than their counterparts in blood. Only skin ILC3s expressed uniquely detected proteins. Our in-depth proteomic dataset allowed us to define the cluster of differentiation marker profiles of the ILC subsets, explore distribution and abundance of proteins known to have immunological functions, as well as identify subset-specific proteins that have not previously been implicated in ILC biology. Taken together, our analyses substantially expand understanding of the protein expression signatures of ILC subsets. Going forward, these proteomic datasets will serve as valuable resources for future studies of ILC biology.

Effects of amber LED on inflammatory and regulatory monocytes and lymphocytes

The primary objective of the present study was to assess the impact of amber LED photobiomodulation (PBM) on human monocytes and lymphocytes that were polarized into proinflammatory and regulatory/reparative phenotypes. Human leukocytes were polarized with LPS or LPS + IL-4 for 2 h and irradiated after 2 and 6 h with amber LED (590 nm). Cell absorbance spectrum and gene and protein expression of IL-1β, IL-6, IL-10, IL-17, TNF-α and IFNγ determined after 24 h. The results showed that irradiation did not significantly alter absorbance of non-polarized monocytes, whereas irradiated polarized monocytes presented reduction in absorbance in 625-850 nm region. Irradiated monocytes polarized with LPS + IL-4 presented reduction in absorbance in 600-725 nm region compared to non-irradiated group. Irradiated non-polarized lymphocytes presented absorbance peaks between 650 and 820 nm not seen in non-irradiated group. No difference was found in absorbance pattern of polarized lymphocytes after irradiation. Irradiation led to reduction in protein synthesis of IL-6 and TNFα in monocytes polarized to proinflammatory phenotype and increase in production of IL-17 in lymphocytes. Irradiation reduced production of IL-10 in monocytes and lymphocytes polarized to immunoregulatory phenotype. In conclusion, amber LED modulates light absorbance and expression of important cytokines in inflammatory/repair processes in monocytes and lymphocytes.

Therapeutic application of human type 2 innate lymphoid cells via induction of granzyme B-mediated tumor cell death

The therapeutic potential for human type 2 innate lymphoid cells (ILC2s) has been underexplored. Although not observed in mouse ILC2s, we found that human ILC2s secrete granzyme B (GZMB) and directly lyse tumor cells by inducing pyroptosis and/or apoptosis, which is governed by a DNAM-1-CD112/CD155 interaction that inactivates the negative regulator FOXO1. Over time, the high surface density expression of CD155 in acute myeloid leukemia cells impairs the expression of DNAM-1 and GZMB, thus allowing for immune evasion. We describe a reliable platform capable of up to 2,000-fold expansion of human ILC2s within 4 weeks, whose molecular and cellular ILC2 profiles were validated by single-cell RNA sequencing. In both leukemia and solid tumor models, exogenously administered expanded human ILC2s show significant antitumor effects in vivo. Collectively, we demonstrate previously unreported properties of human ILC2s and identify this innate immune cell subset as a member of the cytolytic immune effector cell family.

Exploring Immune Cell Diversity in the Lacrimal Glands of Healthy Mice: A Single-Cell RNA-Sequencing Atlas

The lacrimal gland is responsible for maintaining the health of the ocular surface through the production of tears. However, our understanding of the immune system within the lacrimal gland is currently limited. Therefore, in this study, we utilized single-cell RNA sequencing and bioinformatic analysis to identify and analyze immune cells and molecules present in the lacrimal glands of normal mice. A total of 34,891 cells were obtained from the lacrimal glands of mice and classified into 18 distinct cell clusters using Seurat clustering. Within these cell populations, 26 different immune cell subpopulations were identified, including T cells, innate lymphocytes, macrophages, mast cells, dendritic cells, and B cells. Network analysis revealed complex cell-cell interactions between these immune cells, with particularly significant interactions observed among T cells, macrophages, plasma cells, and dendritic cells. Interestingly, T cells were found to be the main source of ligands for the Thy1 signaling pathway, while M2 macrophages were identified as the primary target of this pathway. Moreover, some of these immune cells were validated using immunohistological techniques. Collectively, these findings highlight the abundance and interactions of immune cells and provide valuable insights into the complexity of the lacrimal gland immune system and its relevance to associated diseases.

Type 2 innate lymphoid cells are not involved in mouse bladder tumor development

Therapies for bladder cancer patients are limited by side effects and failures, highlighting the need for novel targets to improve disease management. Given the emerging evidence highlighting the key role of innate lymphoid cell subsets, especially type 2 innate lymphoid cells (ILC2s), in shaping the tumor microenvironment and immune responses, we investigated the contribution of ILC2s in bladder tumor development. Using the orthotopic murine MB49 bladder tumor model, we found a strong enrichment of ILC2s in the bladder under steady-state conditions, comparable to that in the lung. However, as tumors grew, we observed an increase in ILC1s but no changes in ILC2s. Targeting ILC2s by blocking IL-4/IL-13 signaling pathways, IL-5, or IL-33 receptor, or using IL-33-deficient or ILC2-deficient mice, did not affect mice survival following bladder tumor implantation. Overall, these results suggest that ILC2s do not contribute significantly to bladder tumor development, yet further investigations are required to confirm these results in bladder cancer patients.

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

Background

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.

Methods

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.

Results

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.

Conclusion

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.

Single-Cell Transcriptional Analysis of Lamina Propria Lymphocytes in the Jejunum Reveals Innate Lymphoid Cell-like Cells in Pigs

Pigs are the most suitable model to study various therapeutic strategies and drugs for human beings, although knowledge about cell type-specific transcriptomes and heterogeneity is poorly available. Through single-cell RNA sequencing and flow cytometry analysis of the types in the jejunum of pigs, we found that innate lymphoid cells (ILCs) existed in the lamina propria lymphocytes (LPLs) of the jejunum. Then, through flow sorting of live/dead-lineage (Lin)-CD45+ cells and single-cell RNA sequencing, we found that ILCs in the porcine jejunum were mainly ILC3s, with a small number of NK cells, ILC1s, and ILC2s. ILCs coexpressed IL-7Rα, ID2, and other genes and differentially expressed RORC, GATA3, and other genes but did not express the CD3 gene. ILC3s can be divided into four subgroups, and genes such as CXCL8, CXCL2, IL-22, IL-17, and NCR2 are differentially expressed. To further detect and identify ILC3s, we verified the classification of ILCs in the porcine jejunum subgroup and the expression of related hallmark genes at the protein level by flow cytometry. For systematically characterizing ILCs in the porcine intestines, we combined our pig ILC dataset with publicly available human and mice ILC data and identified that the human and pig ILCs shared more common features than did those mouse ILCs in gene signatures and cell states. Our results showed in detail for the first time (to our knowledge) the gene expression of porcine jejunal ILCs, the subtype classification of ILCs, and the markers of various ILCs, which provide a basis for an in-depth exploration of porcine intestinal mucosal immunity.

Single-cell dissection, hdWGCNA and deep learning reveal the role of oxidatively stressed plasma cells in ulcerative colitis

Ulcerative colitis (UC) develops as a result of complex interactions between various cell types in the mucosal microenvironment. In this study, we aim to elucidate the pathogenesis of ulcerative colitis at the single-cell level and unveil its clinical significance. Using single-cell RNA sequencing and high-dimensional weighted gene co-expression network analysis, we identify a subpopulation of plasma cells (PCs) with significantly increased infiltration in UC colonic mucosa, characterized by pronounced oxidative stress. Combining 10 machine learning approaches, we find that the PC oxidative stress genes accurately distinguish diseased mucosa from normal mucosa (independent external testing AUC=0.991, sensitivity=0.986, specificity=0.909). Using MCPcounter and non-negative matrix factorization, we identify the association between PC oxidative stress genes and immune cell infiltration as well as patient heterogeneity. Spatial transcriptome data is used to verify the infiltration of oxidatively stressed PCs in colitis. Finally, we develop a gene-immune convolutional neural network deep learning model to diagnose UC mucosa in different cohorts (independent external testing AUC=0.984, sensitivity=95.9%, specificity=100%). Our work sheds light on the key pathogenic cell subpopulations in UC and is essential for the development of future clinical disease diagnostic tools.

Immune system roles in pathogenesis, prognosis, control, and treatment of Toxoplasma gondii infection

Toxoplasma gondii is the protozoan causative agent of toxoplasmosis in humans and warm-blooded animals. Recent studies have illustrated that the immune system plays a pivotal role in the pathogenesis of toxoplasmosis by triggering immune cytokines like IL-12, TNF-α, and IFN-γ and immune cells like DCs, Th1, and Th17. On the other hand, some immune components can serve as prognosis markers of toxoplasmosis. In healthy people, the disease is often asymptomatic, but immunocompromised people and newborns may suffer severe symptoms and complications. Therefore, the immune prognostic markers may provide tools to measure the disease progress and help patients to avoid further complications. Immunotherapies using monoclonal antibody, cytokines, immune cells, exosomes, novel vaccines, and anti-inflammatory molecules open new horizon for toxoplasmosis treatment. In this review article, we discussed the immunopathogenesis, prognosis, and immunotherapy of Toxoplasma gondii infection.

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.

Dendritic Cell Vaccines Impact the Type 2 Innate Lymphoid Cell Population and Their Cytokine Generation in Mice

Dendritic cell (DC) vaccines can stimulate the immune system to target cancer antigens, making them a promising therapy in immunotherapy. Clinical trials have shown limited effectiveness of DC vaccines, highlighting the need to enhance the immune responses they generate. Innate lymphoid cells (ILCs) are a diverse group of innate leukocytes that produce various cytokines and regulate the immune system. These cells have the potential to improve immunotherapies. There is not much research on how group 2 ILCs (ILC2s) communicate with DC vaccines. Therefore, examining the roles of DC vaccination in immune responses is crucial. Our research analyzed the effects of DC vaccination on the ILC2 populations and their cytokine production. By exploring the relationship between ILC2s and DCs, we aimed to understand how this could affect DC-based immunotherapies. The results showed an increase in the number of ILC2s in the local draining lymph node and spleen of tumor-free mice, as well as in the lungs of mice challenged with tumors in a pulmonary metastasis model. This suggests a complex interplay between DC-based vaccines and ILC2s, which is further influenced by the presence of tumors.

Two-year results of tapered dupilumab for CRSwNP demonstrates enduring efficacy established in the first 6 months

BACKGROUND

Dupilumab is an anti-T2-inflammatory biological registered for chronic rhinosinusitis (CRS) with nasal polyps (CRSwNP), indicated by integrated CRS-care pathways when optimal medico-surgical treatment yields insufficient CRS control. This study aims to evaluate long-term results with focus on established therapeutic efficacy while tapering dupilumab.

METHODS

Real-life, prospective observational cohort study in single tertiary referral center with add-on dupilumab as primary biological treatment in adult (≥18 years) biological-naïve CRSwNP patients per the European Position Paper on Rhinosinusitis and Nasal Polyps (EPOS)2020-indication with a 2-year follow-up. Tapering (increasing interdose interval) applied every 24 weeks, conditional to sufficient treatment response and CRS control.

RESULTS

Mean scores (s.d.) of all co-primary outcomes improved significantly from baseline ( 228) to the 48 ( 214) and 96-weeks ( 99) timepoints: Nasal Polyp Score (0-8) improved from 5,3 (1,9) to 1,4 (1,8) and 1,3 (1,7); SinoNasal Outcome Test (SNOT)-22 (0-110) improved from 53,6 (19,6) to 20,2 (15,4) and 21,2 (15,6); Sniffin'Sticks-12 identification test (0-12; 0-6 anosmia, 7-10 hyposmia, 11-12 normosmia) improved from 3,7 (2,4) to 7,7 (2,9) and 7,3 (3,04); Asthma Control Test (5-25; >19 indicating well-controlled asthma) improved from 18,5 (4,8) to 21,8 (3,8) and 21,4 (3,9). Tapering was feasible in 79,5% of the patients at the 24-weeks timepoint, and in 93,7% and 95,8% at the 48- and 96-weeks timepoints, respectively. One-way repeated-measures ANOVA demonstrated no significant alterations of individual co-primary outcome mean-scores from 24 weeks onward.

CONCLUSION

This first long-term real-life prospective observational cohort study shows high therapeutic efficacy of dupilumab for severe CRswNP in the first 2 years. Therapeutic efficacy is principally established within 24 weeks and endures while tapering dupilumab conditional to treatment response and CRS control.

Chenopodium quinoa's Ingredients Improve Control of the Hepatic Lipid Disturbances Derived from a High-Fat Diet

This study explored the effects of Chenopodium quinoa's ingredients on the major lipids' hepatic profile and the functional selective differentiation of monocyte-derived macrophages and innate lymphoid cells in mice on a high-fat diet. Six-week-old Rag2-/- and Rag2-/-Il2-/- mice received (12 days) a low-molecular-weight protein fraction (LWPF) or the lipid fraction (qLF) obtained from the cold pressing of C. quinoa's germen. At the end of the experiment, mouse serum and liver tissue were collected. The differences in triglycerides, phospholipids, and the major lipids profile were analyzed. Infiltrated monocyte-derived macrophages and innate lymphoid cells (ILCs) and the expression of liver metabolic stress-related mRNA were measured. In the Rag2-/- mice, feeding them LWPF appeared to improve, to a larger extent, their hepatic capacity to utilize fatty acids in comparison to the qLF by preventing the overwhelming of triglycerides (TGs), despite both reducing the hepatic lipid accumulation. An analysis of the hepatic major lipids profile revealed significant increased variations in the PUFAs and phospholipid composition in the Rag2-/- mice fed with the LWPF or LF. The Rag2-/-Il2-/- mice, lacking innate and adaptive lymphocytes, seemed resistant to mobilizing hepatic TGs and unresponsive to lipid accumulation when fed with the LF. Notably, only the Rag2-/- mice fed with the LWPF showed an increased proportion of hepatic CD68+F4/80+ cells population, with a better controlled expression of the innate immune 'Toll-like' receptor (TLR)-4. These changes were associated with an oriented expansion of pluripotential CD117+ cells towards ILC2s (CD117+KLRG1+). Thus, C. quinoa's ingredients resulted in being advantageous for improving the mechanisms for controlling the hepatic lipotoxicity derived from a high-fat diet, promoting liver macrophage and ILCs expansion to a selective functional differentiation for the control of HFD-driven immune and metabolic disturbances.

Identification and characterization of a hepatic IL-13-producing ILC3-like population potentially involved in liver fibrosis

BACKGROUND AND AIMS

Human innate lymphoid cells (ILCs) are critically involved in the modulation of homeostatic and inflammatory processes in various tissues. However, only little is known about the composition of the intrahepatic ILC pool and its potential role in chronic liver disease. Here, we performed a detailed characterization of intrahepatic ILCs in both healthy and fibrotic livers.

APPROACH AND RESULTS

A total of 50 livers (nonfibrotic = 22, and fibrotic = 29) were analyzed and compared with colon and tonsil tissue (each N = 14) and peripheral blood (N = 32). Human intrahepatic ILCs were characterized ex vivo and on stimulation using flow cytometry and single-cell RNA sequencing. ILC differentiation and plasticity were analyzed by both bulk and clonal expansion experiments. Finally, the effects of ILC-derived cytokines on primary human HSteCs were studied. Unexpectedly, we found that an "unconventional" ILC3-like cell represented the major IL-13-producing liver ILC subset. IL-13 + ILC3-like cells were specifically enriched in the human liver, and increased frequencies of this cell type were found in fibrotic livers. ILC3-derived IL-13 production induced upregulation of proinflammatory genes in HSteCs, indicating a potential role in the regulation of hepatic fibrogenesis. Finally, we identified KLRG1-expressing ILC precursors as the potential progenitor of hepatic IL-13 + ILC3-like cells.

CONCLUSIONS

We identified a formerly undescribed subset of IL-13-producing ILC3-like cells that is enriched in the human liver and may be involved in the modulation of chronic liver disease.

Transcriptional and chromatin profiling of human blood innate lymphoid cell subsets sheds light on HIV-1 pathogenesis

Innate lymphoid cells (ILCs) are a diverse population of cells that include NK cells and contribute to tissue homeostasis and repair, inflammation, and provide protection from infection. The interplay between human blood ILCs, as well as their responses to HIV-1 infection, remains poorly understood. This study used transcriptional and chromatin profiling to explore these questions. Transcriptional profiling and flow cytometry analysis support that there are four main ILC subsets found in human blood. Unlike in mice, human NK cells expressed the tissue repair protein amphiregulin (AREG). AREG production was induced by TCF7/WNT, IL-2, and IL-15, and inhibited by TGFB1, a cytokine increased in people living with HIV-1. In HIV-1 infection, the percentage of AREG+ NK cells correlated positively with the numbers of ILCs and CD4+ T cells but negatively with the concentration of inflammatory cytokine IL-6. NK-cell knockout of the TGFB1-stimulated WNT antagonist RUNX3 increased AREG production. Antiviral gene expression was increased in all ILC subsets from HIV-1 viremic people, and anti-inflammatory gene MYDGF was increased in an NK-cell subset from HIV-1-infected people whose viral load was undetectable in the absence of antiretroviral therapy. The percentage of defective NK cells in people living with HIV-1 correlated inversely with ILC percentage and CD4+ T-cell counts. CD4+ T cells and their production of IL-2 prevented the loss of NK-cell function by activating mTOR. These studies clarify how ILC subsets are interrelated and provide insight into how HIV-1 infection disrupts NK cells, including an uncharacterized homeostatic function in NK cells.

The enrichment of Arg1+ILC2s and ILCregs facilitates the progression of endometriosis: A preliminary study

Innate lymphoid cells (ILCs) are a kind of lymphocytes that reside in the tissue and have an essential function in the immune microenvironment. However, the relationship between endometriosis (EMS) and ILCs is complex and not fully understood. This study examines several groups of ILCs in the peripheral blood (PB), peritoneal fluid (PF) and endometrium of patients with EMS via flow cytometry. The study observed an increase in PB ILCs, particularly ILC2s and ILCregs subsets and Arg1+ILC2s in the EMS patients were highly activated. EMS patients had significantly higher levels of serum interleukin (IL)-10/33/25 compared to controls. We also found an elevation of Arg1+ILC2s in the PF and higher levels of ILC2s and ILCregs in ectopic endometrium compared with eutopic. Importantly, a positive correlation was observed between the enrichment of Arg1+ILC2s and ILCregs in the PB of EMS patients. The findings indicate that the involvement of Arg1+ILC2s and ILCregs fosters potentially endometriosis progression.

Targeting Potential of Innate Lymphoid Cells in Melanoma and Other Cancers

Reinvigorating the killing function of tumor-infiltrating immune cells through the targeting of regulatory molecules expressed on lymphocytes has markedly improved the prognosis of cancer patients, particularly in melanoma. While initially thought to solely strengthen adaptive T lymphocyte anti-tumor activity, recent investigations suggest that other immune cell subsets, particularly tissue-resident innate lymphoid cells (ILCs), may benefit from immunotherapy treatment. Here, we describe the recent findings showing immune checkpoint expression on tissue-resident and tumor-infiltrating ILCs and how their effector function is modulated by checkpoint blockade-based therapies in cancer. We discuss the therapeutic potential of ILCs beyond the classical PD-1 and CTLA-4 regulatory molecules, exploring other possibilities to manipulate ILC effector function to further impede tumor growth and quench disease progression.

Systems biology approaches to unravel lymphocyte subsets and function

Single-cell technologies have revealed the extensive heterogeneity and complexity of the immune system. Systems biology approaches in immunology have taken advantage of the high-parameter, high-throughput data and analyzed immune cell types in a 'bottom-up' data-driven method. This approach has discovered previously unrecognized cell types and functions. Especially for human immunology, in which experimental manipulations are challenging, systems approach has become a successful means to investigate physiologically relevant contexts. This review focuses on the recent findings in lymphocyte biology, from their development, differentiation into subsets, and heterogeneity in their functions, enabled by these systems approaches. Furthermore, we review examples of the application of findings from systems approach studies and discuss how now to leave the rich dataset in the curse of high dimensionality.

Natural killer cells and innate lymphoid cells 1 tune anxiety-like behavior and memory in mice via interferon-γ and acetylcholine

The mechanisms of communication between the brain and the immune cells are still largely unclear. Here, we characterize the populations of resident natural killer (NK) cells and innate lymphoid cells (ILC) 1 in the meningeal dura layer of adult mice. We describe that ILC1/NK cell-derived interferon-γ and acetylcholine can contribute to the modulation of brain homeostatic functions, shaping synaptic neuronal transmission and neurotransmitter levels with effects on mice behavior. In detail, the interferon-γ plays a role in the formation of non-spatial memory, tuning the frequency of GABAergic neurotransmission on cortical pyramidal neurons, while the acetylcholine is a mediator involved in the modulation of brain circuitries that regulate anxiety-like behavior. These findings disclose mechanisms of immune-to-brain communication that modulate brain functions under physiological conditions.

Single-cell landscape dissecting the transcription and heterogeneity of innate lymphoid cells in ischemic heart

Background

Until now, few articles have revealed the potential roles of innate lymphoid cells (ILCs) in cardiovascular diseases. However, the infiltration of ILC subsets in ischemic myocardium, the roles of ILC subsets in myocardial infarction (MI) and myocardial ischemia-reperfusion injury (MIRI) and the related cellular and molecular mechanisms have not been described with a sufficient level of detail.

Method

In the current study, 8-week-old male C57BL/6J mice were divided into three groups: MI, MIRI and sham group. Single-cell sequencing technology was used to perform dimensionality reduction clustering of ILC to analyze the ILC subset landscape at a single-cell resolution, and finally flow cytometry was used to confirm the existence of the new ILC subsets in different disease groups.

Results

Five ILC subsets were found, including ILC1, ILC2a, ILC2b, ILCdc and ILCt. It is worth noting that ILCdc, ILC2b and ILCt were identified as new ILC subclusters in the heart. The cellular landscapes of ILCs were revealed and signal pathways were predicted. Furthermore, pseudotime trajectory analysis exhibited different ILC statuses and traced related gene expression in normal and ischemic conditions. In addition, we established a ligand-receptor-transcription factor-target gene regulatory network to disclose cell communications among ILC clusters. Moreover, we further revealed the transcriptional features of the ILCdc and ILC2a subsets. Finally, the existence of ILCdc was confirmed by flow cytometry.

Conclusion

Collectively, by characterizing the spectrums of ILC subclusters, our results provide a new blueprint for understanding ILC subclusters' roles in myocardial ischemia diseases and further potential treatment targets.

The Notch signaling pathway: a potential target for cancer immunotherapy

Dysregulation of the Notch signaling pathway, which is highly conserved across species, can drive aberrant epigenetic modification, transcription, and translation. Defective gene regulation caused by dysregulated Notch signaling often affects networks controlling oncogenesis and tumor progression. Meanwhile, Notch signaling can modulate immune cells involved in anti- or pro-tumor responses and tumor immunogenicity. A comprehensive understanding of these processes can help with designing new drugs that target Notch signaling, thereby enhancing the effects of cancer immunotherapy. Here, we provide an up-to-date and comprehensive overview of how Notch signaling intrinsically regulates immune cells and how alterations in Notch signaling in tumor cells or stromal cells extrinsically regulate immune responses in the tumor microenvironment (TME). We also discuss the potential role of Notch signaling in tumor immunity mediated by gut microbiota. Finally, we propose strategies for targeting Notch signaling in cancer immunotherapy. These include oncolytic virotherapy combined with inhibition of Notch signaling, nanoparticles (NPs) loaded with Notch signaling regulators to specifically target tumor-associated macrophages (TAMs) to repolarize their functions and remodel the TME, combining specific and efficient inhibitors or activators of Notch signaling with immune checkpoint blockers (ICBs) for synergistic anti-tumor therapy, and implementing a customized and effective synNotch circuit system to enhance safety of chimeric antigen receptor (CAR) immune cells. Collectively, this review aims to summarize how Notch signaling intrinsically and extrinsically shapes immune responses to improve immunotherapy.

Innate lymphoid cells and innate-like T cells in cancer - at the crossroads of innate and adaptive immunity

Immunotherapies targeting conventional T cells have revolutionized systemic treatment for many cancers, yet only a subset of patients benefit from these approaches. A better understanding of the complex immune microenvironment of tumours is needed to design the next generation of immunotherapeutics. Innate lymphoid cells (ILCs) and innate-like T cells (ILTCs) are abundant, tissue-resident lymphocytes that have recently been shown to have critical roles in many types of cancers. ILCs and ILTCs rapidly respond to changes in their surrounding environment and act as the first responders to bridge innate and adaptive immunity. This places ILCs and ILTCs as pivotal orchestrators of the final antitumour immune response. In this Review, we outline hallmarks of ILCs and ILTCs and discuss their emerging role in antitumour immunity, as well as the pathophysiological adaptations leading to their pro-tumorigenic function. We explore the pleiotropic, in parts redundant and sometimes opposing, mechanisms that underlie the delicate interplay between the different subsets of ILCs and ILTCs. Finally, we highlight their role in amplifying and complementing conventional T cell functions and summarize immunotherapeutic strategies for targeting ILCs and ILTCs in cancer.