ILC2 Cells Research Articles

Amphiregulin Derived from Multiple Sources Is Important for Barrier Function of the Intestine Following Hematopoietic Stem Cell Transplantation

Conditioning therapy prior to allogeneic hematopoietic stem cell transplantation (allo-SCT) causes damage to the intestinal epithelia, leading to the loss of barrier function. Amphiregulin (AREG), a member of the epidermal growth factor (EGF) family. The EGF family plays an important role in the proliferation and differentiation of the intestinal epithelia1. We have previously shown that co-transplantation of activated type 2 innate lymphoid cells (ILC2) reduced mortality in murine acute GvHD, improved intestinal barrier function following allo-SCT and that ILC2 production of AREG was critical for intestinal repair and restoration of intestinal barrier2. Here we show that isolated intestinal stem cell crypts (ISC) grow and expand significantly when co-cultured with activated ILC2s compared to untreated. We see similar growth in cultures containing media that was conditioned with ILC2 cells for 48 hours prior to use in the organoid cultures. However, both ILC2 culture conditions as well as cultures containing EGF itself. In other experiments ISC co-cultures containing media conditioned with AREG deficient ILC2, IL-13 deficient ILC2 and AREG / IL-13 deficient ILC2 there is significant reduction of organoid growth. These findings further support the role of ILC2 cells during intestinal repair following allo-SCT. ILC2 cells are not the only source of AREG along the GI tract. Intestinal subepithelial myofibroblasts (ISEMF) have been shown to produce AREG in response to radiation treatment in mice.1 To investigate the role of AREG derived from ISEMFs we used a conditional knockout Myh11Cre+/Aregfl/fl strain3 in a B10.BR in to B6 model of acute GvHD. While Myh11Cre+/Aregfl/fl recipients of bone marrow alone all survived long term, Myh11Cre+/Aregfl/fl recipients that also received T cells had significantly increased mortality compared to WT B6 following allo-SCT with a median survival of 10 days and 21 days respectively. Myh11Cre+/Aregfl/fl BM+T recipients also had significantly higher clinical scores than WT B6 controls. Even though Myh11Cre+/Aregfl/fl recipients of BM only did survive long term they did have significantly increased clinical scores in the first 15 days when compared to WT B6. These findings indicate that ISEMF derived AREG is extremely important for early tissue repair following conditioning therapy and allo-SCT. In summary, ILC2s represent a cell population that produce AREG and are required for recovery of GI tract homeostasis following allo-SCT. ISEMFs are also an important source of AREG following transplantation. Additional investigation is needed to fully understand the role of AREG in intestinal health and recovery following allo-SCT.

Absence of ILC2 Recovery Post-Transplant Is Mediated By Epigenetic Conversion of ILC2 to Pro-Inflammatory ILC1-like Cells

Although allogeneic hematopoietic stem cell transplantation (alloHSCT) is the preferred treatment for a variety of hematologic malignancies, its use is limited by the development of acute graft-versus-host disease (aGvHD). Type II innate lymphoid cells (ILC2s) are immune cells that play an important role in maintaining homeostasis in mucosal tissues. Previous work has shown that ILC2 cells fail to reconstitute after chemotherapy or stem cell transplantation, though the mechanism for this finding is unclear. Our group has demonstrated that ILC2s in the GI tract are depleted by chemotherapy or radiation prior to alloHSCT, and that the infusion of donor ILC2s improves the clinical score and survival of recipient mice after transplant. Importantly, ILC2s are also lost in human alloHSCT patients following conditioning therapy. Recent clinical evidence indicates that the presence of ILC2s expressing activation and tissue homing markers are associated with decreased susceptibility to therapy-induced mucositis and aGVHD. Thus, delineation of the mechanisms involved in their turnover and reconstitution could have a significant impact on transplant outcomes. Since the existing dogma is that most ILCs are tissue resident, with only a small circulating pool that can be replenished from the bone marrow, we became interested in understanding why these cells fail to recover and repopulate their niche in the GI tract after alloHSCT. Given that current studies investigating ILC biology across multiple mucosal compartments in both mice and human demonstrate significant ILC plasticity, we evaluated the hypothesis that the loss of ILC2 cells post-transplant induced epigenetic changes that convert ILC2 cells to either ILC1 or ILC3-like cells. To address this hypothesis, we used ChIP-, ATAC-, and RNA-sequencing to assess the chromatin landscape and regulation of ILC2 cells expanded ex vivo, as well as those recovered from the GI tract after HSCT in an allo-mismatched murine model. Strikingly, single-cell, multiomic analysis of donor-derived ILC2s after transplantation revealed a previously unreported population of Tbet-expressing, IFN-γ-secreting ILC1-like cells that differentiate from ILC2s in the small intestine lamina propria (exILC2s). To recapitulate this transdifferentiation, we modeled skewing of ILC2s in vitro with IL-12, IL-1β, and IL-18 and observed a reduction in Type 2 lineage-defining regulatory factors (LDRFs) and the acquisition of proinflammatory Type 1 LDRFs consistent with the phenotype and function of IFN-γ-secreting exILC2s. To determine how these regulatory changes occur, we examined transcription factors with motifs present in regions of open chromatin that were differentially expressed in our transcriptome data between 'true ILC2s' and ILC1-like exILC2 cells recovered from the small intestine. Excitingly, this approach confirms the role of Tbx21 as an "on-off" switch for ILC fate in this model and reveals the early immediate response gene Nr4a2 as an additional key driver of the emergent ILC1-like exILC2s after alloHSCT. To test whether these in vitro generated exILC2s contribute to aGVHD-mediated mortality, we infused transdifferentiated donor WT or exILC2s and measured the clinical score and survival of recipient mice after alloHSCT in a mismatched murine model. Unlike their unmanipulated WT ILC2 counterparts, our in vitro-derived exILC2s failed to ameliorate gut aGvHD and instead accelerated morbidity and mortality. These data demonstrate, for the first time, that ILC2s fail to repopulate their protective niche after alloHSCT due to epigenetic reprogramming and pathological transdifferentiation. These findings provide novel insights into the contribution of ILC plasticity to mucosal dysregulation and aGvHD pathogenesis after alloHSCT, and may inform new approaches for modulating innate lymphocytes in human disease.

Promoting Effect of L-Fucose on the Regeneration of Intestinal Stem Cells through AHR/IL-22 Pathway of Intestinal Lamina Propria Monocytes.

The recovery of the intestinal epithelial barrier is the goal for curing various intestinal injurious diseases, especially IBD. However, there are limited therapeutics for restoring intestinal epithelial barrier function in IBD. The stemness of intestinal stem cells (ISCs) can differentiate into various mature intestinal epithelial cells, thus playing a key role in the rapid regeneration of the intestinal epithelium. IL-22 secreted by CD4+ T cells and ILC3 cells was reported to maintain the stemness of ISCs. Our previous study found that L-fucose significantly ameliorated DSS-induced colonic inflammation and intestinal epithelial injury. In this study, we discovered enhanced ISC regeneration and increased intestinal IL-22 secretion and its related transcription factor AHR in colitis mice after L-fucose treatment. Further studies showed that L-fucose promoted IL-22 release from CD4+ T cells and intestinal lamina propria monocytes (LPMCs) via activation of nuclear AHR. The coculture system of LPMCs and intestinal organoids demonstrated that L-fucose stimulated the proliferation of ISCs through an indirect manner of IL-22 from LPMCs via the IL-22R-p-STAT3 pathway, and restored TNF-α-induced organoid damage via IL-22-IL-22R signaling. These results revealed that L-fucose helped to heal the epithelial barrier by accelerating ISC proliferation, probably through the AHR/IL-22 pathway of LPMCs, which provides a novel therapy for IBD in the clinic.

Antagonism of m3 Alleviates Type 2 Inflammation in Allergic Rhinitis Mice.

Type 2 immune cells play a pivotal role in allergic rhinitis (AR). Increasing evidence shows that inhibition of cholinergic nerve activity decreases the severity of airway diseases including asthma and AR. However, the role of the cholinergic receptor muscarinic 3 (m3) in type 2 inflammation in AR is unknown. We aimed to investigate the effect of m3 on the type 2 immune response, including both T helper 2 (Th2)-mediated and type 2 innate lymphocyte (ILC2)-mediated inflammation, in AR. Peripheral blood mononuclear cells (PBMCs) from human were cultured in vitro. Treatment with the m3 antagonist 1,1-dimethyl-4-diphenylacetoxypiperidinium iodide (4-DAMP) was used. The percentages of Th2 and ILC2 cells in PBMCs were evaluated by flow cytometry. AR mouse models were established by house dust mite (HDM) sensitization, and treated with tiotropium intranasally. The expression of Th2 cytokines, ILC2 cytokines and related factors in the nasal mucosa was assessed by immunohistochemistry and quantitative real-time polymerase chain reaction. Serum HDM-specific immunoglobulin E (sIgE) level was detected by enzyme-linked immunosorbent assay. Both Th2 and ILC2 percentages in PBMCs were decreased after 4-DAMP treatment. Similarly, the levels of Th2 cytokines (interleukin 4 [IL-4] and IL-13) and ILC2 cytokines and related factors (IL-25, IL-33, GATA3 and RORα) were significantly decreased in the nasal mucosa of AR mice after tiotropium treatment. Furthermore, tiotropium treatment decreased the nasal symptom score, the serum sIgE level and eosinophil infiltration in AR mice. In addition, tiotropium decreased phospholipase Cγ1 (PLCγ1), PLCγ2, nuclear factor of activated T cell 1 (NFATc1), and NFATc2 mRNA levels in AR mice. Antagonism of m3 alleviated type 2 inflammation in the nasal mucosa of AR mice.

Gegen Qinlian decoction activates AhR/IL-22 to repair intestinal barrier by modulating gut microbiota-related tryptophan metabolism in ulcerative colitis mice

Ethnopharmacological relevanceGegen Qinlian decoction (GQD) is a traditional Chinese medicine derived from Treatise on febrile diseases and is clinically used for the treatment of acute ulcerative colitis (UC). However, the potential mechanism of GQD treatment for UC remains elusive. Aim of studyIn this study, we aimed to explore the involvement of gut microbiota-related tryptophan metabolism in mediating protective effects of GQD against intestinal barrier damage. Materials and methodsMice with colitis were treated with 3% dextran sulfate sodium (DSS) for 6 days. The therapeutic effects of GQD in UC mice were examined based on body weight, disease activity index (DAI), organ index, length and pathological changes in the colon. The distribution of fluorescein isothiocyanate dextran (FITC-dextran) in the intestinal tract was observed using small animal imaging, while concentration of FITC-dextran in serum was detected using a fluorescein microplate analyser. Bacterial infiltration in colon tissues was observed by fluorescence in situ hybridisation (FISH), and the bacterial load in mesenteric lymph nodes (MLNs) was further examined through bacterial culture. Subsequently, colonic goblet cells were detected using Alcian blue staining. The tight junctions of the colonic epithelium were observed using transmission electron microscopy, and the expression of tight junction proteins was detected by immunofluorescence (IF) and western blot. In addition, flow cytometry was used to analyse the proportion of interleukin-22-positive (IL-22+) ILC3 cells in lamina propria lymphocytes, and the content of IL-22 in colon homogenates was determined using an ELISA kit. In addition, targeted tryptophan metabolomics was used to detect the concentration of indole derivatives produced by tryptophan metabolism in faeces, and 16S rDNA was used to investigate the composition and abundance of gut microbiota-related tryptophan metabolism. ResultsAdministration of GQD significantly alleviated the pathological symptoms, including weight loss, increased DAI score, changes in organ index, colon shortening, and colon pathological injury in UC mice. In addition, GQD reduced the diffusion of FITC-dextran in the intestinal tract, the content of FITC-dextran in serum, and bacterial infiltration in MLNs and colon tissues. Additionally, GQD significantly increased the number of colonic goblet cells, repaired the structure of epithelial tight junctions and increased the expression of tight junction proteins. Furthermore, GQD significantly increased the proportion of IL-22+ ILC3 in the lamina propria, the expression of CYP1A1 protein in colon tissue, and the level of IL-22 in colon homogenates. However, the above protective effects of GQD were inhibited by co-administration of GQD and aryl hydrocarbon receptor (AhR) antagonist. Additionally, GQD restored the content of indole derivatives generated by tryptophan metabolism, regulated the diversity of the gut microbiota, and significantly increased the abundance of genes related to tryptophan metabolism. ConclusionOur results confirmed that GQD repaired the damaged intestinal barrier in UC mice by regulating gut microbiota-related tryptophan metabolism and restoring the generation of indole derivatives to activate AhR-mediated IL-22 production.

How the Immune System Responds to Allergy Immunotherapy.

IgE-mediated diseases represent a highly diversified and multifactorial group of disorders that can deeply impact the patients' quality of life. Currently, allergy immunotherapy (AIT) still remains the gold standard for the management of such pathologies. In this review, we comprehensively examine and discuss how AIT can affect both the innate and the adaptive immune responses at different cell levels and propose timing-scheduled alterations induced by AIT by hypothesizing five sequential phases: after the desensitization of effector non-lymphoid cells and a transient increase of IgE (phase 1), high doses of allergen given by AIT stimulate the shift from type 2/type 3 towards type 1 response (phase 2), which is progressively potentiated by the increase of IFN-γ that promotes the chronic activation of APCs, progressively leading to the hyperexpression of Notch1L (Delta4) and the secretion of IL-12 and IL-27, which are essential to activate IL-10 gene in Th1 and ILC1 cells. As consequence, an expansion of circulating memory Th1/Tr1 cells and ILC-reg characterizes the third phase addressed to antagonize/balance the excess of type 1 response (phase 3). The progressive increase of IL-10 triggers a number of regulatory circuits sustained by innate and adaptive immune cells and favoring T-cell tolerance (phase 4), which may also be maintained for a long period after AIT interruption (phase 5). Different administration approaches of AIT have shown a similar tailoring of the immune responses and can be monitored by timely, optimized biomarkers. The clinical failure of this treatment can occur, and many genetic/epigenetic polymorphisms/mutations involving several immunological mechanisms, such as the plasticity of immune responses and the induction/maintenance of regulatory circuits, have been described. The knowledge of how AIT can shape the immune system and its responses is a key tool to develop novel AIT strategies including the engineering of allergen or their epitopes. We now have the potential to understand the precise causes of AIT failure and to establish the best biomarkers of AIT efficacy in each phase of the treatment.

OMIP-086: Full spectrum flow cytometry for high-dimensional immunophenotyping of mouse innate lymphoid cells.

This 25-parameter, 22-color full spectrum flow cytometry panel was designed and optimized for the comprehensive enumeration and functional characterization of innate lymphoid cell (ILC) subsets in mouse tissues. The panel presented here allows the discrimination of ILC progenitors (ILCP), ILC1, ILC2, NCR+ ILC3, NCR- ILC3, CCR6+ lymphoid tissue-inducer (LTi)-like ILC3 and mature natural killer (NK) cell populations. Further characterization of ILC and NK cell functional profiles in response to stimulation is provided by the inclusion of subset-specific cytokine markers, and proliferation markers. Development and optimization of this panel was performed on freshly isolated cells from adult BALB/c lungs and small intestine lamina propria, and ex vivo stimulation with phorbol 12-myrisate 13-acetate, ionomycin, and pro-ILC activating cytokines.

Disturbed natural killer cell homeostasis in the salivary gland enhances autoimmune pathology via IFN-γ in a mouse model of primary Sjögren’s syndrome

Innate lymphoid cells (ILCs), including natural killer (NK) cells, ILC1, ILC2, lymphoid tissue-inducer (LTi) cells, and ILC3 cell, play a key role in various immune responses. Primary Sjögren's syndrome (pSS) is an autoimmune disease characterized by chronic inflammation of exocrine glands, such as the lacrimal and salivary glands (SGs). The role of NK cells among ILCs in the pathogenesis of pSS is still unclear. In this study, the characteristics and subsets of NK cells in the salivary gland (SG) tissue were analyzed using a murine model of pSS. Multiple phenotypes and cytotoxic signature of the SG NK cells in control and pSS model mice were evaluated by flow cytometric analysis. Intracellular expression of interferon-γ (IFN-γ) among T cells and NK cells from the SG tissues was compared by in vitro experiments. In addition, pathological analysis was performed using anti-asialo-GM1 (ASGM1) antibody (Ab)-injected pSS model mice. The number of conventional NK (cNK) cells in the SG of pSS model mice significantly increased compared with that in control mice at 6 weeks of age. The production level of IFN-γ was significantly higher in SG NK cells than in SG T cells. The depletion of NK cells by ASGM1 Ab altered the ratio of tissue resident NK (rNK) cells to cNK cells, which inhibited the injury to SG cells with the recovery of saliva secretion in pSS model mice. The results indicate that SG cNK cells may enhance the autoreactive response in the target organ by upregulating of IFN-γ, whereas SG rNK cells protect target cells against T cell cytotoxicity. Therefore, the activation process and multiple functions of NK cells in the target organ could be helpful to develop potential markers for determining autoimmune disease activity and target molecules for incurable immune disorders.

Epithelial cell alarmin cytokines: Frontline mediators of the asthma inflammatory response.

The exposure of the airway epithelium to external stimuli such as allergens, microbes, and air pollution triggers the release of the alarmin cytokines IL-25, IL-33 and thymic stromal lymphopoietin (TSLP). IL-25, IL-33 and TSLP interact with their ligands, IL-17RA, IL1RL1 and TSLPR respectively, expressed by hematopoietic and non-hematopoietic cells including dendritic cells, ILC2 cells, endothelial cells, and fibroblasts. Alarmins play key roles in driving type 2-high, and to a lesser extent type 2-low responses, in asthma. In addition, studies in which each of these three alarmins were targeted in allergen-challenged mice showed decreased chronicity of type-2 driven disease. Consequently, ascertaining the mechanism of activity of these upstream mediators has implications for understanding the outcome of targeted therapies designed to counteract their activity and alleviate downstream type 2-high and low effector responses. Furthermore, identifying the factors which shift the balance between the elicitation of type 2-high, eosinophilic asthma and type-2 low, neutrophilic-positive/negative asthma by alarmins is essential. In support of these efforts, observations from the NAVIGATOR trial imply that targeting TSLP in patients with tezepelumab results in reduced asthma exacerbations, improved lung function and control of the disease. In this review, we will discuss the mechanisms surrounding the secretion of IL-25, IL-33, and TSLP from the airway epithelium and how this influences the allergic airway cascade. We also review in detail how alarmin-receptor/co-receptor interactions modulate downstream allergic inflammation. Current strategies which target alarmins, their efficacy and inflammatory phenotype will be discussed.

Circulating T Cell Subsets and ILC2s are Altered in Patients With Chronic Rhinosinusitis With Nasal Polyps After Dupilumab Treatment.

Chronic rhinosinusitis with nasal polyps (CRSwNP) is mainly associated with type 2 inflammation and is often unmanageable, regardless of the treatment. Dupilumab, a monoclonal antibody targeting the interleukin (IL)-4 receptor alpha to inhibit IL-4 and IL-13 signaling, has recently been shown to significantly improve the condition of patients with CRSwNP. However, the mechanisms underlying this response to dupilumab are not yet fully understood. We sought to examine whether circulating T cell subset proportions and their functions are altered by dupilumab treatment. We first investigated the proportion of circulating T cell subsets and group 2 innate immune cells (ILC2s) in patients with CRSwNP treated with dupilumab using mass and flow cytometry. We then assessed cytokine gene expression and cytokine production in peripheral blood mononuclear cells (PBMCs) using quantitative reverse transcription polymerase chain reaction (RT-PCR) and enzyme-linked immunosorbent assay (ELISA). The type 2 T helper (Th2) cell proportion significantly decreased after dupilumab treatment, whereas that of type 1 T helper (Th1) cells increased. Moreover, programmed death-1 (PD-1) expression in regulatory T (Treg) cells was significantly reduced. The proportion of ILC2s significantly increased after dupilumab treatment. Unfortunately, neither cytokine gene expression nor cytokine production in PBMCs showed significant changes. Our findings suggest that in CRSwNP patients treated with dupilumab, Th2, Treg, and ILC2 cells, which regulate type 2 inflammation, are modulated in the peripheral circulation. Further analysis of circulating immune cells could provide novel insights into understanding the pathophysiologic mechanisms of dupilumab and the development of tailored therapeutic strategies for patients with CRSwNP.

Phenotypic features of innate lymphoid cells in rheumatoid arthritis

Currently, rheumatoid arthritis (RA) is considered among the most common autoimmune diseases worldwide, being associated with progressing disability, systemic organ and tissue lesions, as well as social and economic losses for the state. Studies of innate lymphoid cells (ILS) seems to be actual and significant when studying development of autoimmune inflammation in RA, in particular, the issues of the cell plasticity. ILC represent tissue resident lymphoid cells that display functional diversity, like as T cells. Moreover, ILC regulate orientation of immune response by means of cytokine production. Small amounts of ILCs are present in the bloodstream, presumably for migration to target organs and tissues. Accordingly, the study of ILC in RA will promote understanding of the RA pathogenesis. It is also possible in the future to develop new therapeutic strategies based on the impact on the immunological balance, as well as reducing the inflammatory process in RA. The aim of this study was to determine the subpopulation composition and phenotypic features of ILCs in RA.
 We have isolated and studied peripheral blood mononuclear cells (PBMC) from 7 patients with RA and 6 healthy donors. The isolated blood MNCs were stained with monoclonal antibodies conjugated to fluorochromes: lineage-specific (CD3/14/16/19/20/56) and anti-FceR1 alpha-FITC, anti-CD294-APC/Cy7, anti-CD127-PerCP/Cy5.5, anti-CD336-PE, anti-CD117-APC. ILCs were defined as Lin-CD127+. The numbers of CD294+ILCs (ILC2) were estimated in the general population, CD117-CD294-ILCs were defined as ILC1, and CD117+CD294-ILCs, as ILC3. The cell phenotype was analyzed with a FACS Canto II flow cytometer (BD Biosciences, USA).
 We determined relative numbers of different ILC subpopulations (ILC1, ILC2, and ILC3) among the total blood MNCs. It was shown, that the number of ILC2 cells in RA patients was statistically significantly reduced compared to healthy donors, whereas no significant differences in percentage of ILC1 and ILC3 were revealed between donors and patients. We also evaluated the amount of c-Kit+ILC2; there were no significant differences in the proportion of these cells between donors and patients.
 ILCs represent a population of cells that contribute to the RA pathogenesis. The role of ILC2 in RA is, presumably, protective. The ILC imbalance may contribute to the development of RA. For a better understanding of the RA pathogenesis, further studies of the subpopulation profile, phenotypic and functional characteristics of ILC are required in this disorder.

Patrolling ILC3 cells monitor intestinal tissue in response to inflammation

Patrolling ILC3 cells monitor intestinal tissue in response to inflammation

Human periodontitis-associated salivary microbiome affects the immune response of diabetic mice

ABSTRACT Background The bidirectional association between periodontitis and diabetes mellitus has been well accepted; however, pathways connecting them remain unclear. Some oral bacteria are able to induce immunologic changes favoring insulin resistance individually. However, it is unclear if and how the systemic immune system responds to a disturbed oral microbial community in diabetic sufferers. Aim This study aimed to investigate the impact of the human periodontitis-associated salivary microbiome on the splenic immune responses of diabetic mice. Methods An in vivo diabetic animal model was established by feeding high fat food. After microbial depletion with quadruple antibiotic treatment, human saliva from healthy and periodontitis volunteers was transplanted into the mouth of these diabetic mice (N = 3), respectively. Results Osteoclasts and expression levels of TNF-α and IL-1β were significantly increased in periodontal tissues of mice receiving periodontitis patients donated microbiome compared to these transplanted with healthy subjects donated microbiome. The proportion of monocyte (an innate immunocyte) decreased in mice receiving periodontitis patients donated microbiome. However, the abundance of an adaptive immunocyte Th17 was up-regulated. The IL17 production of ILC3 cells in human periodontitis-associated salivary microbiome recipient mice was significantly impaired. Conclusions A disturbed oral microbiome imposes a stress on the splenic immune responses of diabetic mice.

Blocking DCIR mitigates colitis and prevents colorectal tumors by enhancing the GM-CSF-STAT5 pathway.

Dendritic cell immunoreceptor (DCIR; Clec4a2), a member of the C-type lectin receptor family, plays important roles in homeostasis of the immune and bone systems. However, the intestinal role of this molecule is unclear. Here, we show that dextran sodium sulfate (DSS)-induced colitis and azoxymethane-DSS-induced intestinal tumors are reduced in Clec4a2-/- mice independently of intestinal microbiota. STAT5 phosphorylation and expression of Csf2 and tight junction genes are enhanced, while Il17a and Cxcl2 are suppressed in the Clec4a2-/- mouse colon, which exhibits reduced infiltration of neutrophils and myeloid-derived suppressor cells. Granulocyte-macrophage colony-stimulating factor (GM-CSF) administration ameliorates DSS colitis associated with reduced Il17a and enhanced tight junction gene expression, whereas anti-GM-CSF exacerbates symptoms. Furthermore, anti-NA2, a ligand for DCIR, ameliorates colitis and prevents colorectal tumors. These observations indicate that blocking DCIR signaling ameliorates colitis and suppresses colonic tumors, suggesting DCIR as a possible target for the treatment of these diseases.

Highlights from Recent Cancer Literature

Highlights from Recent Cancer Literature

Current Concepts of Vitiligo Immunopathogenesis.

Vitiligo is an acquired immune-mediated disorder of pigmentation clinically characterized by well-defined depigmented or chalk-white macules and patches on the skin. The prevalence of vitiligo varies by geographical area, affecting 0.5% to 2% of the population. The disease imposes a significant psychological burden due to its major impact on patients’ social and emotional aspects of life. Given its autoimmune background, vitiligo is frequently associated with other autoimmune diseases or immune-mediated diseases. Vitiligo is a multifaceted disorder that involves both genetic predisposition and environmental triggers. In recent years, major predisposing genetic loci for the development of vitiligo have been discovered. The current findings emphasize the critical role of immune cells and their mediators in the immunopathogenesis of vitiligo. Oxidative-stress-mediated activation of innate immunity cells such as dendritic cells, natural killer, and ILC-1 cells is thought to be a key event in the early onset of vitiligo. Innate immunity cells serve as a bridge to adaptive immunity cells including T helper 1 cells, cytotoxic T cells and resident memory T cells. IFN-γ is the primary cytokine mediator that activates the JAK/STAT pathway, causing keratinocytes to produce the key chemokines CXCL9 and CXCL10. Complex interactions between immune and non-immune cells finally result in apoptosis of melanocytes. This paper summarizes current knowledge on the etiological and genetic factors that contribute to vitiligo, with a focus on immunopathogenesis and the key cellular and cytokine players in the disease’s inflammatory pathways.

Cigarette smoke aggravates asthma by inducing memory-like type 3 innate lymphoid cells

Although cigarette smoking is known to exacerbate asthma, only a few clinical asthma studies have been conducted involving smokers. Here we show, by comparing paired sputum and blood samples from smoking and non-smoking patients with asthma, that smoking associates with significantly higher frequencies of pro-inflammatory, natural-cytotoxicity-receptor-non-expressing type 3 innate lymphoid cells (ILC3) in the sputum and memory-like, CD45RO-expressing ILC3s in the blood. These ILC3 frequencies positively correlate with circulating neutrophil counts and M1 alveolar macrophage frequencies, which are known to increase in uncontrolled severe asthma, yet do not correlate with circulating eosinophil frequencies that characterize allergic asthma. In vitro exposure of ILCs to cigarette smoke extract induces expression of the memory marker CD45RO in ILC3s. Cigarette smoke extract also impairs the barrier function of airway epithelial cells and increases their production of IL-1β, which is a known activating factor for ILC3s. Thus, our study suggests that cigarette smoking increases local and circulating frequencies of activated ILC3 cells, plays a role in their activation, thereby aggravating non-allergic inflammation and the severity of asthma.

Type 2 inflammation in asthma and other airway diseases.

Chronic inflammatory airway diseases, including asthma, chronic rhinosinusitis, eosinophilic COPD and allergic rhinitis are a global health concern. Despite the coexistence of these diseases and their common pathophysiology, they are often managed independently, resulting in poor asthma control, continued symptoms and poor quality of life. Understanding disease pathophysiology is important for best treatment practice, reduced disease burden and improved patient outcomes.The pathophysiology of type 2 inflammation is driven by both the innate immune system triggered by pollutants, viral or fungal infections involving type 2 innate lymphoid cells (ILC2) and the adaptive immune system, triggered by contact with an allergen involving type 2 T-helper (Th2) cells. Both ILC2 and Th2 cells produce the type-2 cytokines (interleukin (IL)-4, IL-5 and IL-13), each with several roles in the inflammation cascade. IL-4 and IL-13 cause B-cell class switching and IgE production, release of pro-inflammatory mediators, barrier disruption and tissue remodelling. In addition, IL-13 causes goblet-cell hyperplasia and mucus production. All three interleukins are involved in trafficking eosinophils to tissues, producing clinical symptoms characteristic of chronic inflammatory airway diseases.Asthma is a heterogenous disease; therefore, identification of biomarkers and early targeted treatment is critical for patients inadequately managed by inhaled corticosteroids and long-acting β-agonists alone. The Global Initiative for Asthma guidelines recommend add-on biological (anti IgE, IL-5/5R, IL-4R) treatments for those not responding to standard of care. Targeted therapies, including omalizumab, mepolizumab, reslizumab, benralizumab, dupilumab and tezepelumab, were developed on current understanding of the pathophysiology of type 2 inflammation. These therapies offer hope for improved management of type 2 inflammatory airway diseases.

Dihydromyricetin Improves High-Fat Diet-Induced Hyperglycemia through ILC3 Activation via a SIRT3-Dependent Mechanism.

Previous studies indicate that dihydromyricetin (DHM) effectively improved glucose homeostasis and alleviated insulin resistance in population-intervened trials, yet the underlying mechanism remains obscure. Wild-type male mice and recombinase activating gene 1(Rag1)-/- mice (lacking adaptive immunity lymphocytes) are fed with control, high-fat diet (HFD), or HFD+DHM diets for 8 weeks. DHM effectively protects HFD feeding mice against hyperglycemia by promoting group 3 innate lymphoid cells (ILC3s) cells proliferation and interleukin 22 (IL-22) production. Furthermore, IL-22 secretion induced by DHM increases the expression levels of the tight junction (TJs) molecules to protect the intestinal barrier integrity, thereby decreasing the level of lipopolysaccharides (LPS), an endotoxin that is involved in the regulation of chronic tissue inflammation and insulin resistance. In addition, silent mating-type information regulation 2 homolog 3 (SIRT3) deficiency results in more serious obesity and intestinal barrier damage following HFD feeding and abolished DHM-mediated increase in IL-22 expression levels of ILC3 cells in SIRT3 knockout (SIRT3KO) mice. DHM reduces metabolic stress and enhances mitochondrial respiratory capacity to promote cell proliferation and IL-22 secretion by activating SIRT3 in ILC3 cells CONCLUSIONS: DHM improves IL-22 production of ILC3 cells and subsequently inhibits intestinal barrier dysfunction to alleviate hyperglycemia partially mediated by SIRT3.

Checkpoint Inhibitors Modulate Plasticity of Innate Lymphoid Cells in Peripheral Blood of Patients With Hepatocellular Carcinoma.

Innate lymphoid cells (ILC) are a heterogeneous and plastic population of cells of the innate immune system. Their role in cancer and specifically in hepatocellular carcinoma is unraveling. The presence of ILCs in peripheral blood of HCC patients has not been explored yet. Their role and function in response to checkpoint inhibitor therapy have also not been explored. Here, we characterized ILCs in PBMC of HCC patients at baseline and after treatment with immune checkpoint inhibitors (ICI) by flow cytometry and single-cell sequencing. Characterization of ILC subsets in PBMCs of HCC patients showed a significant increase in ILC1 and a decrease in ILC3 frequencies. Single-cell RNA-sequencing identified a subgroup of NK-like ILCs which expressed cytotoxicity markers as well as NKp80/KLRF1. This KLRF1high NK-like population showed low abundance in patients with HCC and was enhanced after combined anti-CTLA-4 and anti-PD-1immunotherapy. Trajectory analysis placed this population in between ILC1 and ILC3 cells. The transcriptomic signature of KLRF1high NK-like ILCs was associated with better progression-free survival in large HCC cohorts. This study shows a previously unknown effect of ICI on the composition and plasticity of ILCS in peripheral blood. Thus, ILCs from PBMC can be used to study changes in the innate immune system under immunotherapy.