Search Results (44)

Group 2 innate lymphoid cells (ILC2s) are tissue-resident immune cells that play a central role in type 2 immunity. Beyond cytokine signaling, they integrate inputs from lipids, nutrients, neuroendocrine mediators, and local metabolic cues, establishing cellular metabolism as a key regulator of their function. Immunometabolism provides a framework to understand how ILC2s adapt to diverse tissue environments such as the lung, adipose tissue, gut, skin, and brain, each defined by distinct nutrient availability, oxygen tension, and inflammatory conditions. Unlike many immune cells that primarily rely on glycolysis, ILC2s dynamically balance glycolysis, fatty acid oxidation (FAO), and oxidative phosphorylation (OXPHOS) depending on activation state and tissue context. Lipids not only serve as energy substrates but also regulate membrane organization, lipid raft–dependent signaling, and the generation of bioactive mediators, including eicosanoids, oxysterols, and sphingolipids. Emerging evidence linking cholesterol biosynthesis, steroid metabolism, and sphingolipid signaling to ILC2 function underscores the importance of lipid-dependent immune regulation. Dysregulation of these pathways contributes to chronic inflammatory diseases such as asthma, metabolic disorders, and fibrosis. Targeting metabolic pathways and checkpoints may therefore offer new strategies to modulate ILC2-driven pathology. This review summarizes current insights into metabolic programs governing ILC2 activation, survival, and plasticity and highlights emerging therapeutic opportunities. Full article

Helminths infect a quarter of the human population and are controlled in the frame of a canonical type-2 immune response. Interleukin-9 is a cytokine with pleiotropic functions during type-2 immunity that can be produced by many different cells. Accumulating evidence suggest that IL-9 is of particular relevance in controlling intestinal helminth infections. Using mice infected with the parasitic nematode Strongyloides ratti, we showed previously that ejection from the intestine depends on IL-9 and IL-9-mediated activation of mucosal mast cells. Here we use IL-9 reporter mice to identify the relevant cellular sources of IL-9 in vivo. We report that predominantly CD4⁺ T cells and group 2 innate lymphoid cells (ILC2s) produced IL-9 in S. ratti-infected or IL-33-treated mice. Interestingly, the IL-33-mediated induction of IL-9 and subsequent mast cell degranulation was modulated by concurrent S. ratti infection. While the IL-33-mediated expansion of IL-9-producing ILC2s was supressed by S. ratti infection, IL-9-producing CD4⁺ T cells were proportionally increased. Finally, we show that S. ratti-derived E/S products interfered with IL-9 production by BM-derived ILC2 in vitro. In conclusion, we have identified that ILC2 and CD4⁺ T cells produce IL-9 during S. ratti infection, and that ILC2 responses are suppressed by S. ratti products. Full article

The concept of united airway disease (UAD) highlights the bidirectional relationship between inflammatory disorders of the upper airways—such as allergic rhinitis and chronic rhinosinusitis with or without nasal polyps (CRSwNP/CRSsNP)—and lower airway diseases, most notably asthma. This paradigm is supported by epidemiological, embryological, and immunological evidence demonstrating that airway inflammation represents a single, interconnected process rather than isolated compartmental pathology. Central to many UAD phenotypes is type 2 (T2) inflammation, driven by cytokines including IL-4, IL-5, and IL-13, and mediated by effector cells such as eosinophils and group 2 innate lymphoid cells (ILC2s). Epithelial barrier dysfunction often serves as the initiating trigger for this shared inflammatory cascade by production of TSLP, IL-25 and IL-33. Optimal diagnosis and management of UAD require an integrated, multidisciplinary framework. Clinical evaluation remains essential for patient characterization but must be complemented by pheno-endotypic assessment using imaging (CT), allergy testing, biomarker profiling (FeNO, blood eosinophils, IgE), and pulmonary function testing (spirometry, impulse oscillometry). Therapeutic strategies are layered, targeting both symptom control and inflammation across airway compartments. Standard approaches include intranasal and inhaled corticosteroids as well as saline irrigations, while severe T2-high disease increasingly benefits from biologic therapies (anti-IL-5/IL-5R, anti-IL-4R, anti-TSLP), which reduce dependence on systemic corticosteroids and surgical interventions such as endoscopic sinus surgery (ESS). Emerging precision-medicine models, particularly the “treatable traits” approach, further underscore the need to view the airway as a unified system. Collectively, these insights reinforce the clinical imperative of addressing upper and lower airway disease as a continuum, ensuring that inflammation in one district is neither overlooked nor treated in isolation. Full article

Der p 23 induces a high-frequency sensitization in allergic individuals. However, its allergenic activity and clinical impact are scarce. We aimed to evaluate the ability of rDer p 23 to induce allergic inflammation in a mouse model and to test IgE reactivity in humans. Female Balb/c mice were sensitized and challenged with rDer p 23 and Dermatophagoides pteronyssinus extract. Specific antibodies were determined by ELISA, inflammatory cell infiltration and goblet cells hyperplasia were evaluated by lung histology, and bronchial hyperreactivity (BHR) was assessed by the FinePoint RC System^TM and whole-body plethysmography (WBP). IgE reactivity was evaluated by ELISA, the basophils activation test (BAT) and the skin pick test (SPT) in humans. rDer p 23, produced in Escherichia coli, adopts a random coil structure, predominantly exists in a monomeric state, and exhibits high stability. rDer p 23-treated mice showed a significant increase in lung resistance and bronchial hyperreactivity, as well as in eosinophils, neutrophils, and T cell count in bronchoalveolar lavage fluid (BALF). Cytokine and antibodies profiles were biased to a Type-2 response. No significant difference was observed in group 2 Innate Lymphoid Cells (ILC-2s) in lung and regulatory T cells (Treg) in the spleen. In asthmatic individuals sensitized to D. pteronyssinus, serum IgE reactivity to rDer p 23 was 67.5%. BAT and SPT results were significantly higher in allergic patients. Our findings support the pro-allergenic role of rDer p 23 in the development of the pathological features of asthma. Full article

Mouse models serve as a means of examining immune changes when genes of interest are knocked out (KO). One group of immune gene-producing cells that have been identified is type 2 innate lymphoid cells (Ilc2). These cells are involved in the production of Th2 equivalent immune responses and signal cytokine production during the resolution of Nippostrongylus brasiliensis parasite infection in mice lungs. However, many questions about Ilc2 activity in the gut remain. To study this, retinoic acid receptor (RAR)-related orphan receptor alpha (RORα)-deficient mice were infected with adult N. brasiliensis and arranged into four treatment groups. Ten days post-infection (dpi), mouse ileum tissue was extracted for RNA-Seq. The RORα-deficient mice showed little change in gene expression at 10 dpi (N = 51) when compared to the WT mice at 10 dpi (N = 915), displaying dysregulation within the mouse gut. Based on the results, the gene expression in the gut of Ilc2-deficient mice denoted that the inability to craft Ilc2 cells left the mice unable to mount classical helminth immune responses involving humoral, mast cell, and antibody Th2-driven reactions. Overall, the results showed the importance of Ilc2 in the gut during N. brasiliensis infections and the effect that the lack of these cells had on immunity. Full article

(1) Background: The IL-36 cytokines have been identified as key contributors to pustular psoriasis, and their inhibitor is already in clinical use. However, few studies have explored them in atopic dermatitis. (2) Methods: The role of IL-36α was investigated in various atopic dermatitis models using wild-type, keratin 14-specific IL-33 transgenic, IL-18 transgenic, caspase-1 transgenic, and caspase-1 transgenic mice with IL-17AF deletion, reflecting diverse aspects of human skin inflammation. IL-36α was administered subcutaneously in five doses on alternate days across the five strains to examine cellular infiltration patterns and cytokine expression levels. (3) Results: The skin phenotype was exacerbated, accompanied by worsening edema and skin thickness in all mouse groups upon IL-36α administration. An increase in infiltrating cells was observed among innate immune cells, while lymphocyte counts, including T cells and innate lymphoid cells, did not rise. Additionally, anti-inflammatory cytokines were induced simultaneously with inflammatory cytokines and downstream cytokines of IL-36α as well. Infiltrating lymphocytes in the skin displayed a distinct Type 2 cytokine-dominant profile for innate lymphoid cells and a Type 3 cytokine-dominant profile for T helper cells and γδ T cells, contrasting with the Type 1-dominant cell profile in draining lymph nodes. Type 1, Type 2, and Type 3 cytokine dominance patterns were not affected by the administration of IL-36α. (4) Conclusions: IL-36α triggers inflammatory responses in atopic dermatitis by activating innate immunity. The infiltrating lymphocytes in the skin have different cytokine production profiles between innate lymphoid cells and T cells, as well as different patterns of cytokine production in their draining lymph nodes. Full article

Background: Growing evidence attests to the multifaceted roles of group 2 innate lymphoid cells (ILC2s) in cancer immunity. They exhibit either pro- or anticancer activity depending on tumor type but their function in Multiple Myeloma (MM) is still not elucidated. Methods: The bone marrow (BM) and peripheral blood (PB) of patients (pts) with MM or precancerous conditions were collected, and specific properties of ILC2 subsets were assessed by flow cytometry. Results: By dissecting ILC2s according to c-Kit marker, we observed that NKp30 and NKG2D were mainly confined to c-Kit^hi ILC2s, while levels of DNAM-1 was significantly higher in fully mature c-Kit^lo cells. Among the total MM-associated ILC2s (MM-ILC2s), we observed a significant increase in c-the Kit^lo subset, but the expression of DNAM-1 in these cells was significantly reduced, especially in BM. Interestingly, MM-ILC2s from PB expressed granzyme B (GZMB), but its expression was impaired in BM-ILC2s. Accordingly, MM cells were susceptible to killing by MM-ILC2s derived from PB while eluding ILC2 surveillance in BM. Indeed, in MM-ILC2s derived from BM, the downregulation of DNAM-1 is accompanied by the upregulation of TIGIT, which mediate cell death in ILC2s upon recognition of the cognate ligands expressed by MM cells. These ILC2 changes appeared in clinical precursor conditions and eventually accumulated with disease progression. Conclusions: MM-ILC2s can act as cytolytic immune effectors that are fully competent in PB. However, MM cells shift ILC2 fate towards cell death in BM via the upregulation of TIGIT, thereby representing a potential therapeutic target to restore ILC2 antitumor activity. Full article

In patients with aspirin-exacerbated respiratory disease (AERD), there is disparate regulation of prostaglandin E2 (PGE₂) and prostaglandin D₂ (PGD₂). Both prostanoids are synthesised by cyclooxygenase 1 (COX-1) and cyclooxygenase 2 (COX-2). However, while the basal synthesis of PGE₂ tends to decrease, that of PGD₂ increases in patients with AERD. Furthermore, both behave differently in response to the inhibitory action of NSAIDs on COX-1: PGE₂ levels decrease while PGD₂ increases. Increased PGD₂ release correlates with nasal, bronchial, and extra-pulmonary symptoms caused by aspirin in AERD. The proposed hypothesis establishes that the answer to this paradoxical dissociation can be found in the airway epithelium. This is based on the observation that reduced COX-2 mRNA and/or protein expression is associated with reduced PGE₂ synthesis in cultured fibroblast and epithelial cells from AERD compared to patients with asthma who are aspirin-tolerant and healthy subjects. The low production of PGE₂ by the airway epithelium in AERD results in an excessive release of alarmins (TSLP, IL-33), which in turn contributes to activating group 2 innate lymphoid cells (ILC2s) and PGD₂ synthesis by mast cells and eosinophils. Aspirin, by further increasing the diminished PGE₂ regulation capacity in AERD, leads to respiratory reactions associated with the surge in PGD₂ from mast cells and eosinophils. In summary, the downregulation of COX-2 and the subsequent low production of PGE₂ by airway cells account for the apparently paradoxical increased production of PGD₂ by mast cells and eosinophils at the baseline and after aspirin provocation in patients with AERD. A better understanding of the role of the airway epithelium would contribute to elucidating the mechanism of AERD. Full article

Asthma is a chronic respiratory condition predominantly driven by a type 2 immune response. Epithelial-derived alarmins such as thymic stromal lymphopoietin (TSLP), interleukin (IL)-33, and IL-25 orchestrate the activation of downstream Th2 cells and group 2 innate lymphoid cells (ILC2s), along with other immune effector cells. While these alarmins are produced in response to inhaled triggers, such as allergens, respiratory pathogens or particulate matter, disproportionate alarmin production by airway epithelial cells can lead to asthma exacerbations. With alarmins produced upstream of the type 2 inflammatory cascade, understanding the pathways by which these alarmins are regulated and expressed is critical to further explore new therapeutics for the treatment of asthmatic patients. This review emphasizes the critical role of airway epithelium and epithelial-derived alarmins in asthma pathogenesis and highlights the potential of targeting alarmins as a promising therapeutic to improve outcomes for asthma patients. Full article

Chronic exposure to harmful pollutants, chemicals, and pathogens from the environment can lead to pathological changes in the epithelial barrier, which increase the risk of developing an allergy. During allergic inflammation, epithelial cells send proinflammatory signals to group 2 innate lymphoid cell (ILC2s) and eosinophils, which require energy and resources to mediate their activation, cytokine/chemokine secretion, and mobilization of other cells. This review aims to provide an overview of the metabolic regulation in allergic asthma, atopic dermatitis (AD), and allergic rhinitis (AR), highlighting its underlying mechanisms and phenotypes, and the potential metabolic regulatory roles of eosinophils and ILC2s. Eosinophils and ILC2s regulate allergic inflammation through lipid mediators, particularly cysteinyl leukotrienes (CysLTs) and prostaglandins (PGs). Arachidonic acid (AA)-derived metabolites and Sphinosine-1-phosphate (S1P) are significant metabolic markers that indicate immune dysfunction and epithelial barrier dysfunction in allergy. Notably, eosinophils are promoters of allergic symptoms and exhibit greater metabolic plasticity compared to ILC2s, directly involved in promoting allergic symptoms. Our findings suggest that metabolomic analysis provides insights into the complex interactions between immune cells, epithelial cells, and environmental factors. Potential therapeutic targets have been highlighted to further understand the metabolic regulation of eosinophils and ILC2s in allergy. Future research in metabolomics can facilitate the development of novel diagnostics and therapeutics for future application. Full article

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

SARS-CoV-2 infection has claimed just over 1.1 million lives in the US since 2020. Globally, the SARS-CoV-2 respiratory infection spread to 771 million people and caused mortality in 6.9 million individuals to date. Much of the early literature showed that SARS-CoV-2 immunity was defective in the early stages of the pandemic, leading to heightened and, sometimes, chronic inflammatory responses in the lungs. This lung-associated ‘cytokine storm’ or ‘cytokine release syndrome’ led to the need for oxygen supplementation, respiratory distress syndrome, and mechanical ventilation in a relatively high number of people. In this study, we evaluated circulating PBMC from non-hospitalized, male and female, COVID-19+ individuals over the course of infection, from the day of diagnosis (day 0) to one-week post diagnosis (day 7), and finally 4 weeks after diagnosis (day 28). In our early studies, we included hospitalized and critically care patient PBMC; however, most of these individuals were lymphopenic, which limited our assessments of their immune integrity. We chose a panel of 30 interferon-stimulated genes (ISG) to evaluate by PCR and completed flow analysis for immune populations present in those PBMC. Lastly, we assessed immune activation by stimulating PBMC with common TLR ligands. We identified changes in innate cells, primarily the innate lymphoid cells (ILC, NK cells) and adaptive immune cells (CD4+ and CD8+ T cells) over this time course of infection. We found that the TLR-7 agonist, Resiquimod, and the TLR-4 ligand, LPS, induced significantly better IFN$\alpha$ and IFN$\gamma$ responses in the later phase (day 28) of SARS-CoV-2 infection in those non-hospitalized COVID-19+ individuals as compared to early infection (day 0 and day 7). We concluded that TLR-7 and TLR-4 agonists may be effective adjuvants in COVID-19 vaccines for mounting immunity that is long-lasting against SARS-CoV-2 infection. Full article

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. Full article

This review explores the ‘gut–lung axis’ in asthma with a focus on commensal fungal organisms. We explore how changes to the intestinal commensal fungal community composition alter lung immune function. We comprehensively review available studies that have profiled the composition of the gut mycobiome in adults and children with asthma, and discuss mechanisms of gut–lung interactions that have been described in animal models of asthma. Studies indicate that intestinal fungal dysbiosis, such as an increased abundance of certain fungi like Candida, can elevate the risk of asthma in children and exacerbate it in adults. This effect is mediated through various pathways: the host immune system’s sensing of dysbiosis via C-type lectin receptors (e.g., Dectin-2), the impact of pro-inflammatory fungal metabolites (e.g., 12,13-diHOME, prostaglandin E2), and the role of lung immune cells (e.g., group 2 innate lymphoid cells [ILC2], M2 macrophages). We also describe strategies for modulating the gut mycobiome as potential therapies for severe asthma. The review concludes by emphasizing the necessity for further research into the role of the gut mycobiome in asthma to deepen our understanding of these complex interactions. Full article

Eosinophilic asthma is the most prevalent and well-defined phenotype of asthma. Despite a majority of patients responding to corticosteroid therapy and T2 biologics, there remains a subset that have recurrent asthma exacerbations, highlighting a need for additional therapies to fully ameliorate airway eosinophilia. Group 2 innate lymphoid cells (ILC2) are considered key players in the pathogenesis of eosinophilic asthma through the production of copious amounts of type 2 cytokines, namely IL-5 and IL-13. ILC2 numbers are increased in the airways of asthmatics and with the greatest numbers of activated ILC2 detected in sputa from severe prednisone-dependent asthma with uncontrolled eosinophilia. Although epithelial-derived cytokines are important mediators of ILC2 activation, emerging evidence suggests that additional pathways stimulate ILC2 function. The tumor necrosis factor super family (TNFSF) and its receptors (TNFRSF) promote ILC2 activity. In this review, we discuss evidence supporting a relationship between ILC2 and TNFSF/TNFRSF axis in eosinophilic asthma and the role of this relationship in severe asthma with airway autoimmune responses. Full article