Biology and therapeutic potential of human innate lymphoid cells

Spatial mapping of innate lymphoid cells in human lymphoid tissues and lymphoma at single-cell resolution

Innate lymphoid cells (ILC) distribution and compartmentalization in human lymphoid tissues are incompletely described. Through combined multiplex immunofluorescence, multispectral imaging, and advanced computer vision methods, we provide a map of ILCs at the whole-slide single-cell resolution level, and study their proximity to T helper (Th) cells. The results show that ILC2 predominates in thymic medulla; by contrast, immature Th cells prevail in the cortex. Unexpectedly, we find that Th2-like and Th17-like phenotypes appear before complete T cell receptor gene rearrangements in these immature thymocytes. In the periphery, ILC2 are more abundant in lymph nodes and tonsils, penetrating lymphoid follicles. NK cells are uncommon in lymphoid tissues but abundant in the spleen, whereas ILC1 and ILC3 predominate in the ileum and appendix. Under pathogenic conditions, a deep perturbation of both ILC and Th populations is seen in follicular lymphoma compared with non-neoplastic conditions. Lastly, all ILCs are preferentially in close proximity to their Th counterparts. In summary, our histopathology tool help present a spatial mapping of human ILCs and Th cells, in normal and neoplastic lymphoid tissues.

The impact of a single HIIT intervention on the mobilization of NK cells and ILCs in adolescents and young adults (AYA) undergoing cancer treatment: an interventional controlled trial

OBJECTIVE

The study investigated the response of immune cells, particularly natural killer (NK) cells and innate lymphoid cells (ILCs), to acute exercise in adolescents and young adults (AYAs) undergoing cancer treatment, to lower their treatment burden and evaluate the value of exercise in this vulnerable cohort.

METHODS

An AYA cancer patient group (PG) (n = 20, 25 ± 7 years old) and an age-matched healthy control group (HG) (n = 20, 27 ± 5 years old) completed a twenty-minute high intensity interval training (HIIT) on a bicycle ergometer. Blood was taken at three timepoints during the intervention. Once immediately before (T0), once immediately after the intervention (T1), and after one-hour of recovery (T2). NK cells, ILCs, respectively their subpopulations, were determined by flow cytometry.

RESULTS

Total NK cells (PG: p = 0.023; HG: p = 0.004), CD56dimNK cells (PG: p = 0.035; HG: p = 0.004), total ILCs (PG: p < 0.001; HG: p < 0.001), ILC1-like (PG: p = 0.001; HG: p = 0.004), ILC2 (PG: p = 0.006; HG: p = 0.003) and innate lymphoid cell precursors (ILCPs) (PG: p = 0.009; HG: p = 0.002) increased significantly from T0 to T1. CD56brightNK cells (HG: p = 0.011) increased significantly only in the HG. From T1 to T2 total NK cells (PG: p < 0.001; HG: p < 0.001), CD56dimNK cells (PG: p < 0.001; HG: p < 0.001), CD56brightNK cells (PG: p < 0.001; HG: p < 0.001), ILC2 (PG: p = 0.035; HG: p = 0.007) and ILCPs (PG: p = 0.006; HG: p = 0.003) decreased significantly. ILC1-like maintained their elevated cell count plateau during the recovery phase. No significant differences were found for NKp44+ILC3 and for inter-group comparisons regarding the percentage changes of cell counts from T0 to T1 or T1 to T2. Younger age and higher heart rates (in percentage of age-predicted maximal heart rate) during the intervention were associated with an increased mobilization of immune cells, especially in NK cells and their subpopulations.

CONCLUSION

We were able to show, that HIIT enhances the mobilization of NK cells and ILCs to the same extend in AYA cancer patients than in healthy controls. Our pilot study revealed, that exercise is likely to play an important role in the defense against pathogens and neoplastic cells and that AYA cancer patients might benefits from regular exercise programs during anti-cancer treatment.

TRIAL REGISTRATION

The study was registered on 13.11.2022, registration number NCT05656651, in the international register of clinical trials https://www.

CLINICALTRIALS

gov/ .

Short-term oral zinc supplementation enhances Natural Killer cell functionality and decreases circulating Innate Lymphoid Cell counts and frequencies in healthy young adults

BACKGROUND

Zinc is an essential trace element with high importance for immune function. Previous research has shown that vegetarians and vegans are at increased risk of zinc deficiency, due to low zinc bioavailability in plant-based food. However, its effects on immune parameters in healthy adults following these diets remain largely unexplored. Therefore, this study investigated the effects of dietary patterns, serum zinc levels, and short-term oral zinc supplementation on Natural Killer (NK) cells, circulating Innate Lymphoid Cells (cILCs), and NK cell functionality in omnivores, vegetarians, and vegans.

METHODS

A total of 54 study participants, including 21 omnivores, 18 vegetarians, and 15 vegans were enrolled in our study. NK cell and cILC counts and frequencies were analyzed by flow cytometry and NK cell cytotoxicity assay was performed and compared between the three dietary cohorts as well as between zinc adequate (ZA) and zinc deficient (ZD) individuals. Based on serum zinc concentrations and/or Food Frequency Questionnaire (FFQ) scores, study participants classified as ZD were supplemented with 10 mg zinc daily for 14 days. After this period, the same experiments were performed.

RESULTS

Our results show that neither dietary patterns nor baseline zinc levels significantly affect cILC or NK cell counts, frequencies, or NK cell cytotoxicity. However, short-term oral zinc supplementation significantly reduced cILC counts and frequencies, while enhancing NK cell functionality. Here, NK cell cytotoxicity is significantly positively correlated, whereas cILC counts are negatively correlated with serum zinc concentrations. Remarkably, 72% of all study participants, including 48% of omnivores, were classified as ZD.

CONCLUSIONS

Since proper NK cell functionality is required for early defense against infected or malignant cells, and cILCs act as progenitors to replenish tissue resident ILCs, which are crucial for tissue homeostasis and barrier integrity, our results suggest that routine zinc supplementation might be a simple yet effective strategy to enhance immune defense and potentially prevent diseases across different dietary groups.

TRIAL REGISTRATION

The study was approved and registered by the Institutional Ethics Committee of the Medical Faculty of RWTH Aachen University on the 19th of July 2023 (study numbers: EK 23-148 and EK 23-234, CTC number: 23-163).

Physiopathological Roles of White Adiposity and Gut Functions in Neuroinflammation

White adipose tissue (WAT) and the gut are involved in the development of neuroinflammation when an organism detects any kind of injury, thereby triggering metainflammation. In fact, the autonomous nervous system innervates both tissues, although the complex role played by the integrated sympathetic, parasympathetic, and enteric nervous system functions have not been fully elucidated. Our aims were to investigate the participation of inflamed WAT and the gut in neuroinflammation. Firstly, we conducted an analysis into how inflamed peripheral WAT plays a key role in the triggering of metainflammation. Indeed, this included the impact of the development of local insulin resistance and its metabolic consequences, a serious hypothalamic dysfunction that promotes neurodegeneration. Then, we analyzed the gut-brain axis dysfunction involved in neuroinflammation by examining cell interactions, soluble factors, the sensing of microbes, and the role of dysbiosis-related mechanisms (intestinal microbiota and mucosal barriers) affecting brain functions. Finally, we targeted the physiological crosstalk between cells of the brain-WAT-gut axis that restores normal tissue homeostasis after injury. We concluded the following: because any injury can result not only in overall insulin resistance and dysbiosis, which in turn can impact upon the brain, but that a high-risk of the development of neuroinflammation-induced neurodegenerative disorder can also be triggered. Thus, it is imperative to avoid early metainflammation by applying appropriate preventive (e.g., lifestyle and diet) or pharmacological treatments to cope with allostasis and thus promote health homeostasis.

Exogenous IL-33 promotes tumor immunity via macroscopic regulation of ILC2s

Interleukin-33 (IL-33) is a pleiotropic molecule that plays various roles in the body. However, how exogenous IL-33 changes the tumor immune microenvironment remains unclear. Our study revealed that exogenous IL-33 exerts anti-tumor effects and effectively suppresses the progression of subcutaneous melanoma. scRNA-seq analysis revealed that exogenous IL-33 reduced neutrophils accumulation, thereby improving the inhibitory immune environment. Flow cytometry analysis revealed that exogenous IL-33 significantly increased the proportion of eosinophils and group 2 innate lymphoid cells (ILC2s). In addition, we identified genes encoding major histocompatibility complex (MHC) class II molecules in this group of ILC2s, suggesting that ILC2s may play a role in antigen presentation. In Il7rCreArg1flox/flox mice, the decrease of ILC2s led to a reduction in the proportion of eosinophils. Furthermore, we found that exogenous IL-33 effectively promoted the differentiation of ILC2s and their accumulation in tumors, thereby enhancing the anti-tumor immune response. These findings may pave the way for developing new cancer immunotherapies that use IL-33 as an activator to enhance anti-tumor immune responses.

Circulating innate lymphoid cells (cILCs): Unconventional lymphocytes with hidden talents

Innate lymphoid cells (ILCs) are a group of lymphocytes that are devoid of antigen-specific receptors and are mainly found in tissues. The subtypes ILC1, 2, and 3 mirror T-cell functionality in terms of cytokine production and expression of key transcription factors. Although the majority of ILCs are found in tissue (tILCs), they have also been described within the circulation (cILCs). As a result of their better accessibility and putative prognostic value, human cILCs are getting more and more attention in clinical research. However, cILCs are in many aspects functionally distinct from their tILC counterparts. In fact, from the 3 ILC subsets found within the circulation, only for cILC2s could a clear functional correspondence to their tissue counterparts be established. Indeed, cILC2s are emerging as a major driver of allergic reactions with a particular role in asthma. In contrast, recent studies revealed that cILC1s and cILC3s are predominantly in an immature state and constitute progenitors for natural killer cells and ILCs, respectively. We provide an overview about the phenotype and function of the different cILC subtypes compared to tILCs in health and disease, including transcriptomic signatures, frequency dynamics, and potential clinical value. Furthermore, we will highlight the dynamics of the NKp44+ ILC3 subset, which emerges as prognostic marker in peripheral blood for inflammatory bowel disease and leukemia.

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.

Inhalant Cannabidiol Inhibits Glioblastoma Progression Through Regulation of Tumor Microenvironment

Introduction: Glioblastoma (GBM) is the most common invasive brain tumor composed of diverse cell types with poor prognosis. The highly complex tumor microenvironment (TME) and its interaction with tumor cells play important roles in the development, progression, and durability of GBM. Angiogenic and immune factors are two major components of TME of GBM; their interplay is a major determinant of tumor vascularization, immune profile, as well as immune unresponsiveness of GBM. Given the ineffectiveness of current standard therapies (surgery, radiotherapy, and concomitant chemotherapy) in managing patients with GBM, it is necessary to develop new ways of treating these lethal brain tumors. Targeting TME, altering tumor ecosystem may be a viable therapeutic strategy with beneficial effects for patients in their fight against GBM. Materials and Methods: Given the potential therapeutic effects of cannabidiol (CBD) in a wide spectrum of diseases, including malignancies, we tested, for the first time, whether inhalant CBD can inhibit GBM tumor growth using a well-established orthotopic murine model. Optical imaging, histology, immunohistochemistry, and flow cytometry were employed to describe the outcomes such as tumor progression, cancer cell signaling pathways, and the TME. Results: Our findings showed that inhalation of CBD was able to not only limit the tumor growth but also to alter the dynamics of TME by repressing P-selectin, apelin, and interleukin (IL)-8, as well as blocking a key immune checkpoint-indoleamine 2,3-dioxygenase (IDO). In addition, CBD enhanced the cluster of differentiation (CD) 103 expression, indicating improved antigen presentation, promoted CD8 immune responses, and reduced innate Lymphoid Cells within the tumor. Conclusion: Overall, our novel findings support the possible therapeutic role of inhaled CBD as an effective, relatively safe, and easy to administer treatment adjunct for GBM with significant impacts on the cellular and molecular signaling of TME, warranting further research.

Modulation of innate lymphoid cells by enteric bacterial pathogens

Innate lymphoid cells (ILCs) are key regulators of tissue homeostasis, inflammation, and immunity to infections. ILCs rapidly respond to environmental cues such as cytokines, microbiota and invading pathogens which regulate their function and phenotype. Even though ILCs are rare cells, they are enriched at barrier surfaces such as the gastrointestinal (GI) tract, and they are often critical to the host's immune response to eliminate pathogens. On the other side of host-pathogen interactions, pathogenic bacteria also have the means to modulate these immune responses. Manipulation or evasion of the immune cells is often to the pathogen's benefit and/or to the detriment of competing microbiota. In some instances, specific bacterial virulence factors or toxins have been implicated in how the pathogen modulates immunity. In this review, we discuss the recent progress made towards understanding the role of non-cytotoxic ILCs during enteric bacterial infections, how these pathogens can modulate the immune response, and the implications these have on developing new therapies to combat infection.

Efficient In Vitro Generation of IL-22-Secreting ILC3 From CD34+ Hematopoietic Progenitors in a Human Mesenchymal Stem Cell Niche

Innate lymphoid cells (ILCs) and in particular ILC3s have been described to be vital for mucosal barrier functions and homeostasis within the gastrointestinal (GI) tract. Importantly, IL-22-secreting ILC3 have been implicated in the control of inflammatory bowel disease (IBD) and were shown to reduce the incidence of graft-versus-host disease (GvHD) as well as the risk of transplant rejection. Unfortunately, IL-22-secreting ILC3 are primarily located in mucosal tissues and are not found within the circulation, making access to them in humans challenging. On this account, there is a growing desire for clinically applicable protocols for in vitro generation of effector ILC3. Here, we present an approach for faithful generation of functionally competent human ILC3s from cord blood-derived CD34+ hematopoietic progenitors on layers of human mesenchymal stem cells (MSCs) generated in good manufacturing practice (GMP) quality. The in vitro-generated ILC3s phenotypically, functionally, and transcriptionally resemble bona fide tissue ILC3 with high expression of the transcription factors (TF) RorγT, AHR, and ID2, as well as the surface receptors CD117, CD56, and NKp44. Importantly, the majority of ILC3 belonged to the desired effector subtype with high IL-22 and low IL-17 production. The protocol thus combines the advantages of avoiding xenogeneic components, which were necessary in previous protocols, with a high propensity for generation of IL-22-producing ILC3. The present approach is suitable for the generation of large amounts of ILC3 in an all-human system, which could facilitate development of clinical strategies for ILC3-based therapy in inflammatory diseases and cancer.