Epithelial-derived Cytokines Research Articles

TL1A is an epithelial alarmin that cooperates with IL-33 for initiation of allergic airway inflammation.

Epithelium-derived cytokines or alarmins, such as interleukin-33 (IL-33) and thymic stromal lymphopoietin (TSLP), are major players in type 2 immunity and asthma. Here, we demonstrate that TNF-like ligand 1A (TL1A) is an epithelial alarmin, constitutively expressed in alveolar epithelium at steady state in both mice and humans, which cooperates with IL-33 for early induction of IL-9high ILC2s during the initiation of allergic airway inflammation. Upon synergistic activation by IL-33 and TL1A, lung ILC2s acquire a transient IL-9highGATA3low "ILC9" phenotype and produce prodigious amounts of IL-9. A combination of large-scale proteomic analyses, lung intravital microscopy, and adoptive transfer of ILC9 cells revealed that high IL-9 expression distinguishes a multicytokine-producing state-of-activated ILC2s with an increased capacity to initiate IL-5-dependent allergic airway inflammation. Similar to IL-33 and TSLP, TL1A is expressed in airway basal cells in healthy and asthmatic human lungs. Together, these results indicate that TL1A is an epithelium-derived cytokine and an important cofactor of IL-33 in the airways.

Multifactorial Causes and Consequences of TLSP Production, Function, and Release in the Asthmatic Airway

Disruption of the airway epithelium triggers a defensive immune response that begins with the production and release of alarmin cytokines. These epithelial-derived alarmin cytokines, including thymic stromal lymphopoietin (TSLP), are produced in response to aeroallergens, viruses, and toxic inhalants. An alarmin response disproportionate to the inhaled trigger can exacerbate airway diseases such as asthma. Allergens inhaled into previously sensitized airways are known to drive a T2 inflammatory response through the polarization of T cells by dendritic cells mediated by TSLP. Harmful compounds found within air pollution, microbes, and viruses are also triggers causing airway epithelial cell release of TSLP in asthmatic airways. The release of TSLP leads to the development of inflammation which, when unchecked, can result in asthma exacerbations. Genetic and inheritable factors can contribute to the variable expression of TSLP and the risk and severity of asthma. This paper will review the various triggers and consequences of TSLP release in asthmatic airways.

Endoplasmic reticulum stress enhances the expression of TLR3-induced TSLP by airway epithelium.

Thymic stromal lymphopoietin (TSLP) is an epithelial-derived pleiotropic cytokine that regulates T-helper 2 (Th2) immune responses in the lung and plays a major role in severe uncontrolled asthma. Emerging evidence suggests a role for endoplasmic reticulum (ER) stress in the pathogenesis of asthma. In this study, we determined if ER stress and the unfolded protein response (UPR) signalling are involved in TSLP induction in the airway epithelium. For this, we treated human bronchial epithelial basal cells and differentiated primary bronchial epithelial cells with ER stress inducers and the TSLP mRNA and protein expression was determined. A series of siRNA gene knockdown experiments were conducted to determine the ER stress-induced TSLP signalling pathways. cDNA collected from asthmatic bronchial biopsies was used to determine the gene correlation between ER stress and TSLP. Our results show that ER stress signalling induces TSLP mRNA expression via the PERK-CHOP signalling pathway. AP-1 transcription factor is important in regulating this ER stress-induced TSLP mRNA induction, though ER stress alone cannot induce TSLP protein production. However, ER stress significantly enhances TLR3-induced TSLP protein secretion in the airway epithelium. TSLP and ER stress (PERK) mRNA expression positively correlates in bronchial biopsies from participants with asthma, particularly in neutrophilic asthma. In conclusion, these results suggest that ER stress primes TSLP which is then enhanced further upon TLR3 activation, which may induce severe asthma exacerbations. Targeting ER stress using pharmacological interventions may provide novel therapeutics for severe uncontrolled asthma.

New Drug for Management of Severe Uncontrolled Asthma: Tezepelumab

Abstract: Tezepelumab is a first-in-class human IgG2λ monoclonal antibody used to treat severe, uncontrolled asthma. Tezepelumab acts by hindering the action of thymic stromal lymphopoietin (TSLP), an epithelial-derived cytokine that triggers an immunological response by binding to TSLP and thereby preventing its binding with the TSLP receptor complex. TSLP has a critical role in Th2 immunity and plays an important role in the pathogenesis of asthma because it stimulates the production of Th2-associated inflammatory mediators, such as interleukin-4, interleukin-5, interleukin-9, and interleukin-13. It is the first biologic with no phenotypic or biomarker restrictions that has been approved for use in severe asthma. Tezepelumab is indicated in severe, uncontrolled asthma patients due to its safety, tolerability, and efficacy. Adults with severe, uncontrolled asthma experienced considerably lower annualised asthma exacerbation rates (AAERs) when administered with tezepelumab compared to a placebo. These preliminary results indicated that the TSLP-induced release of T2 inflammatory mediators may be reduced, and the sustained inhibition was maintained over a 52-week treatment period. In this review, we have summarised various phase III clinical trials and the mechanism of action of tezepelumab in severe, uncontrolled asthma.

TNF Superfamily and ILC2 Activation in Asthma.

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.

The effect of combining an inhaled corticosteroid and a long-acting muscarinic antagonist on human airway epithelial cells in vitro

BackgroundAirway epithelial cells (AECs) are a major component of local airway immune responses. Direct effects of type 2 cytokines on AECs are implicated in type 2 asthma, which is driven by epithelial-derived cytokines and leads to airway obstruction. However, evidence suggests that restoring epithelial health may attenuate asthmatic features.MethodsWe investigated the effects of passive sensitisation on IL-5, NF-κB, HDAC-2, ACh, and ChAT in human bronchial epithelial cells (HBEpCs) and the effects of fluticasone furoate (FF) and umeclidinium (UME) alone and in combination on these responses.ResultsIL-5 and NF-κB levels were increased, and that of HDAC-2 reduced in sensitised HEBpCs. Pretreatment with FF reversed the effects of passive sensitisation by concentration-dependent reduction of IL-5, resulting in decreased NF-κB levels and restored HDAC-2 activity. Addition of UME enhanced these effects. Sensitized HEBpCs also exhibited higher ACh and ChAT levels. Pretreatment with UME significantly reduced ACh levels, and addition of FF caused a further small reduction.ConclusionThis study confirmed that passive sensitisation of AECs results in an inflammatory response with increased levels of IL-5 and NF-κB, reduced levels of HDAC-2, and higher levels of ACh and ChAT compared to normal cells. Combining FF and UME was found to be more effective in reducing IL-5, NF-κB, and ACh and restoring HDAC-2 compared to the individual components. This finding supports adding a LAMA to established ICS/LABA treatment in asthma and suggests the possibility of using an ICS/LAMA combination when needed.

Epithelial overexpression of IL-33 induces eosinophilic esophagitis dependent on IL-13

BackgroundEosinophilic esophagitis (EoE) is an increasingly common inflammatory condition of the esophagus; however, the underlying immunologic mechanisms remain poorly understood. The epithelium-derived cytokine IL-33 is associated with type 2 immune responses and elevated in esophageal biopsies from EoE subjects. ObjectiveWe hypothesized that overexpression of IL-33 by the esophageal epithelium would promote the immunopathology of EoE. MethodsWe evaluated the functional consequences of esophageal epithelial overexpression of a secreted and active form of IL-33 (saIL-33) in a novel transgenic mouse, EoE33. EoE33 mice were analyzed for clinical and immunologic phenotypes. Esophageal contractility was assessed. Epithelial cytokine responses were analyzed in three-dimensional organoids. EoE33 phenotypes were further characterized in ST2-/-, eosinophil-deficient, and IL-13-/- mice. Finally, EoE33 mice were treated with dexamethasone. ResultsEoE33 mice displayed ST2-dependent, EoE-like pathology and failed to thrive. Esophageal tissue remodeling and inflammation included basal zone hyperplasia, eosinophilia, mast cells, and Th2 cells. Marked increases in levels of type 2 cytokines, including IL-13, and molecules associated with immune responses and tissue remodeling were observed. Esophageal organoids suggested reactive epithelial changes. Genetic deletion of IL-13 in EoE33 mice abrogated pathological changes in vivo. EoE33 mice were steroid responsive. ConclusionIL-33 overexpression by the esophageal epithelium generated immunopathology and clinical phenotypes resembling human EoE. IL-33 may play a pivotal role in the etiology of EoE by activating the IL-13 pathway. EoE33 mice are a robust experimental platform for mechanistic investigation and translational discovery.

Discovery and Characterization of a Bicyclic Peptide (Bicycle) Binder to Thymic Stromal Lymphopoietin.

Thymic stromal lymphopoietin (TSLP) is an epithelial-derived pro-inflammatory cytokine involved in the development of asthma and other atopic diseases. We used Bicycle Therapeutics' proprietary phage display platform to identify bicyclic peptides (Bicycles) with high affinity for TSLP, a target that is difficult to drug with conventional small molecules due to the extended protein-protein interactions it forms with both receptors. The hit series was shown to bind to TSLP in a hotspot, that is also used by IL-7Rα. Guided by the first X-ray crystal structure of a small peptide binding to TSLP and the identification of key metabolites, we were able to improve the proteolytic stability of this series in lung S9 fractions without sacrificing binding affinity. This resulted in the potent Bicycle 46 with nanomolar affinity to TSLP (KD = 13 nM), low plasma clearance of 6.4 mL/min/kg, and an effective half-life of 46 min after intravenous dosing to rats.

High TSLP responses in the human infant airways are associated with pre-activated airway epithelial IFN antiviral immunity.

Thymic stromal lymphopoietin (TSLP) is a primarily epithelial-derived cytokine that drives type 2 allergic immune responses. Early life viral respiratory infections elicit high TSLP production, which leads to the development of type 2 inflammation and airway hyperreactivity. The goal of this study was to examine in vivo and in vitro the human airway epithelial responses leading to high TSLP production during viral respiratory infections in early infancy. A total of 129 infants (<1-24 m, median age 10 m) with severe viral respiratory infections were enrolled for in vivo (n = 113), and in vitro studies (n = 16). Infants were classified as 'high TSLP' or 'low TSLP' for values above or below the 50th percentile. High versus low TSLP groups were compared in terms of type I-III IFN responses and production of chemokines promoting antiviral (CXCL10), neutrophilic (CXCL1, CXCL5, CXCL8), and type 2 responses (CCL11, CCL17, CCL22). Human infant airway epithelial cell (AEC) cultures were used to define the transcriptomic (RNAseq) profile leading to high versus low TSLP responses in vitro in the absence (baseline) or presence (stimulated) of a viral mimic (poly I:C). Infants in the high TSLP group had greater in vivo type III IFN airway production (median type III IFN in high TSLP 183.2 pg/mL vs. 63.4 pg/mL in low TSLP group, p = 0.007) and increased in vitro type I-III IFN AEC responses after stimulation with a viral mimic (poly I:C). At baseline, our RNAseq data showed that infants in the high TSLP group had significant upregulation of IFN signature genes (e.g., IFIT2, IFI6, MX1) and pro-inflammatory chemokine genes before stimulation. Infants in the high TSLP group also showed a baseline AEC pro-inflammatory state characterized by increased production of all the chemokines assayed (e.g., CXCL10, CXCL8). High TSLP responses in the human infant airways are associated with pre-activated airway epithelial IFN antiviral immunity and increased baseline AEC production of pro-inflammatory chemokines. These findings present a new paradigm underlying the production of TSLP in the human infant airway epithelium following early life viral exposure and shed light on the long-term impact of viral respiratory illnesses during early infancy and beyond childhood.

Hypoxia induces the production of epithelial-derived cytokines in eosinophilic chronic rhinosinusitis with nasal polyps.

Hypoxia plays a significant role in the pathogenesis of chronic rhinosinusitis (CRS). However, the role and mechanism of hypoxia in the type 2 immune response in eosinophilic chronic rhinosinusitis with nasal polyps (ECRSwNP) remain unclear. The expression of hypoxia-inducible factor-1α (HIF-1α) and epithelial-derived cytokines (EDCs), including interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin (TSLP), was detected in nasal polyps via immunohistochemical analysis. The relationship between HIF-1α and EDCs was also elucidated using Pearson's correlation. Moreover, primary human nasal epithelial cells (HNECs) and a mouse model of ECRSwNP were employed to elucidate the role and mechanism of hypoxia in type 2 immune responses. HIF-1α, IL-25, IL-33, and TSLP expression levels were upregulated in the non-ECRSwNP and ECRSwNP groups compared with the control group, with the ECRSwNP group having the highest HIF-1α and EDC expression levels. Additionally, HIF-1α was positively correlated with IL-25 and IL-33 in the ECRSwNP group. Meanwhile, treatment with a HIF-1α inhibitor, PX-478, inhibited the hypoxia-induced increase in the mRNA and protein expression of EDCs and type 2 cytokines in HNECs. Similarly, in vivo, PX-478 inhibited EDC expression in the sinonasal mucosa of mice with ECRSwNP. Hypoxia induces EDC expression by upregulating HIF-1α levels, thereby promoting type 2 immune responses and the development of ECRSwNP. Hence, targeting HIF-1α may represent an effective therapeutic strategy for ECRSwNP.

Airway Epithelial-Derived Immune Mediators in COVID-19.

The airway epithelium, which lines the conducting airways, is central to the defense of the lungs against inhaled particulate matter and pathogens such as SARS-CoV-2, the virus that causes COVID-19. Recognition of pathogens results in the activation of an innate and intermediate immune response which involves the release of cytokines and chemokines by the airway epithelium. This response can inhibit further viral invasion and influence adaptive immunity. However, severe COVID-19 is characterized by a hyper-inflammatory response which can give rise to clinical presentations including lung injury and lead to acute respiratory distress syndrome, viral pneumonia, coagulopathy, and multi-system organ failure. In response to SARS-CoV-2 infection, the airway epithelium can mount a maladaptive immune response which can delay viral clearance, perpetuate excessive inflammation, and contribute to the pathogenesis of severe COVID-19. In this article, we will review the barrier and immune functions of the airway epithelium, how SARS-CoV-2 can interact with the epithelium, and epithelial-derived cytokines and chemokines and their roles in COVID-19 and as biomarkers. Finally, we will discuss these immune mediators and their potential as therapeutic targets in COVID-19.

The Functional Role of Group 2 Innate Lymphoid Cells in Asthma.

Asthma is a heterogeneous disease characterized by chronic airway inflammation. Group 2 innate lymphoid cells (ILC2) play an important role in the pathogenesis of asthma. ILC2s lack antigen-specific receptors and respond to epithelial-derived cytokines, leading to the induction of airway eosinophilic inflammation in an antigen-independent manner. Additionally, ILC2s might be involved in the mechanism of steroid resistance. Numerous studies in both mice and humans have shown that ILC2s induce airway inflammation through inflammatory signals, including cytokines and other mediators derived from immune or non-immune cells. ILC2s and T helper type 2 (Th2) cells collaborate through direct and indirect interactions to organize type 2 immune responses. Interestingly, the frequencies or numbers of ILC2 are increased in the blood and bronchoalveolar lavage fluid of asthma patients, and the numbers of ILC2s in the blood and sputum of severe asthmatics are significantly larger than those of mild asthmatics. These findings may contribute to the regulation of the immune response in asthma. This review article highlights our current understanding of the functional role of ILC2s in asthma.

Hypoxia-inducible factor prolyl hydroxylase inhibitors suppressed thymic stromal lymphopoietin production and allergic responses in a mouse air-pouch-type ovalbumin sensitization model.

Atopic dermatitis (AD) is an allergic skin disease, triggered by excessive type 2 immune reactions. Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine that induces type 2 immune response through dendritic cell activation. Therefore, TSLP inhibitors may serve as novel antiallergic drugs. Hypoxia-inducible factor (HIF) activation in the epithelia contributes to several homeostatic phenomena, such as re-epithelialization. However, the effects of HIF activation on TSLP production and immune activation in the skin remain unclear. In this study, we found that selective HIF prolyl hydroxylase inhibitors (PHD inhibitors), which induce HIF activation, suppressed TSLP production in a mouse ovalbumin (OVA) sensitization model. PHD inhibitors also suppressed the production of tumor necrosis factor-alpha (TNF-α), which is a major inducer of TSLP production, in this mouse model and in a macrophage cell line. Consistent with these findings, PHD inhibitors suppressed OVA-specific IgE levels in the serum and OVA-induced allergic responses. Furthermore, we found a direct suppressive effect on TSLP expression in a human keratinocyte cell line mediated by HIF activation. Taken together, our findings suggest that PHD inhibitors exert antiallergic effects by suppressing TSLP production. Controlling the HIF activation system has therapeutic potential in AD.

Severe Asthmatic Responses: The Impact of TSLP.

Asthma is a chronic inflammatory disease that affects the lower respiratory system and includes several categories of patients with varying features or phenotypes. Patients with severe asthma (SA) represent a group of asthmatics that are poorly responsive to medium-to-high doses of inhaled corticosteroids and additional controllers, thus leading in some cases to life-threatening disease exacerbations. To elaborate on SA heterogeneity, the concept of asthma endotypes has been developed, with the latter being characterized as T2-high or low, depending on the type of inflammation implicated in disease pathogenesis. As SA patients exhibit curtailed responses to standard-of-care treatment, biologic therapies are prescribed as adjunctive treatments. To date, several biologics that target specific downstream effector molecules involved in disease pathophysiology have displayed superior efficacy only in patients with T2-high, eosinophilic inflammation, suggesting that upstream mediators of the inflammatory cascade could constitute an attractive therapeutic approach for difficult-to-treat asthma. One such appealing therapeutic target is thymic stromal lymphopoietin (TSLP), an epithelial-derived cytokine with critical functions in allergic diseases, including asthma. Numerous studies in both humans and mice have provided major insights pertinent to the role of TSLP in the initiation and propagation of asthmatic responses. Undoubtedly, the magnitude of TSLP in asthma pathogenesis is highlighted by the fact that the FDA recently approved tezepelumab (Tezspire), a human monoclonal antibody that targets TSLP, for SA treatment. Nevertheless, further research focusing on the biology and mode of function of TSLP in SA will considerably advance disease management.

BAL Fluid Eosinophilia Associates With Chronic Lung Allograft Dysfunction Risk: A Multicenter Study

Chronic lung allograft dysfunction (CLAD) is the leading cause of death among lung transplant recipients. Eosinophils, effector cells of type 2 immunity, are implicated in the pathobiology of many lung diseases, and prior studies suggest their presence associates with acute rejection or CLAD after lung transplantation. Does histologic allograft injury or respiratory microbiology correlate with the presence of eosinophils in BAL fluid (BALF)? Does early posttransplant BALF eosinophilia associate with future CLAD development, including after adjustment for other known risk factors? We analyzed BALF cell count, microbiology, and biopsy data from a multicenter cohort of 531 lung recipients with 2,592 bronchoscopies over the first posttransplant year. Generalized estimating equation models were used to examine the correlation of allograft histology or BALF microbiology with the presence of BALF eosinophils. Multivariable Cox regression was used to determine the association between≥ 1%BALF eosinophils in the first posttransplant year and definite CLAD. Expression of eosinophil-relevant genes was quantified in CLAD and transplant control tissues. The odds of BALF eosinophils being present was significantly higher at the time of acute rejection and nonrejection lung injury histologies and during pulmonary fungal detection. Early posttransplant≥ 1%BALF eosinophils significantly and independently increased the risk for definite CLAD development (adjusted hazard ratio, 2.04; P= .009). Tissue expression of eotaxins, IL-13-related genes, and the epithelial-derived cytokines IL-33 and thymic stromal lymphoprotein were significantly increased in CLAD. BALF eosinophilia was an independent predictor of future CLAD risk across a multicenter lung recipient cohort. Additionally, type 2 inflammatory signals were induced in established CLAD. These data underscore the need for mechanistic and clinical studies to clarify the role of type 2 pathway-specific interventions in CLAD prevention or treatment.

A novel therapeutic approach for allergic rhinitis by exosome-mimetic nanovesicles derived from mesenchymal stem cells to restore nasal mucosal epithelial barrier

Allergic rhinitis (AR) is one of the most common chronic diseases of the airways worldwide. Nasal epithelial cells (NEpCs) are the first line of defence against invading pathogens in the respiratory tract by providing both physical and immunological barrier. Accumulated evidence points to disruption of the tight junctions between epithelial cells and secretion of cytokines as critical factors necessary for the initiation and development of AR. Mesenchymal stem cells (MSCs) that are derived from the mesoderm during early development, and they secrete various biologically active components showing multiple roles such as immunomodulation, mitigation of inflammation and tissue regeneration. It has been proven that MSC-derived exosomemimetic nanovesicles (MSC-NVs) play similar functional roles to MSCs. We envision that MSC-NVs can restore the nasal mucosal epithelial barrier, improve the immune balance and treat AR by maintaining the integrity of the mucosal epithelial structure and regulating the level of epithelial-derived cytokines.

Anti-epithelial-derived cytokines for severe asthma: Systematic review and meta-analysis

Therapies directed against epithelial-derived cytokines, often referred to as alarmins, have been studied in large randomized trials, and reports suggest possible benefit for non-type 2 as well as type 2 severe asthma. We performed a systematic review of Medline, Embase, Cochrane Central Register of Controlled Trials, Medline In-Process, and Web of Science databases from inception to March 2022. We performed a random-effects pairwise meta-analysis of randomized controlled trials addressing antialarmin therapy in severe asthma. Results use relative risk (RR) values and 95% confidence intervals (CIs). For continuous outcomes, we report mean difference (MD) values and 95% CIs. We define high eosinophils as ≥300 cells/μL and low eosinophils as <300 cells/μL. We used Cochrane-endorsed RoB 2.0 software to assess the risk of bias of trials, and we used the Grades of Recommendation Assessment, Development, and Evaluation (aka GRADE) framework to assess the certainty of the evidence. We identified 12 randomized trials including 2391 patients. Antialarmins probably reduce annualized exacerbation rates in patients with high eosinophils (RR 0.33 [95% CI 0.28 to 0.38]; moderate certainty). Antialarmins may reduce this rate in patients with low eosinophils (RR 0.59 [95% CI 0.38 to 0.90]; low certainty). Antialarmins improve FEV1 in patients with high eosinophils (MD 218.5 mL [95% CI 160.2 to 276.7]; high certainty). Antialarmin therapy probably does not improve FEV1 in patients with low eosinophils (MD 68.8 mL [95% CI 22.4 to 115.2]; moderate certainty). Antialarmins reduce blood eosinophils, total IgE, and fractional excretion of nitric oxide across studied subjects. Antialarmins are effective at improving lung function and probably reduce exacerbations in patients with severe asthma and blood eosinophils ≥300 cells/μL. The effect on patients with lower eosinophils is less certain.

Lung epithelial cells: upstream targets in type 2-high asthma.

Over the last years, technological advances in the field of asthma have led to the identification of two disease endotypes, namely type 2-high and type 2-low asthma, characterized by different pathophysiologic mechanisms at a cellular and molecular level. Although specific immune cells are important contributors to each of the recognized asthma endotype, the lung epithelium is now regarded as a crucial player able to orchestrate responses to inhaled environmental triggers such as allergens and microbes. The impact of the epithelium goes beyond its physical barrier. It is nowadays considered as a part of the innate immune system that can actively respond to insults. Activated epithelial cells, by producing a specific set of cytokines, trigger innate and adaptive immune cells to cause pathology. Here, we review how the epithelium contributes to the development of Th2 sensitization to allergens and asthma with a "type 2-high" signature, in both murine models and human studies of this asthma endotype. We also discuss epithelial responses to respiratory viruses, like RV, RSV and SARS-CoV-2, and how these triggers influence not only asthma development but also asthma exacerbation. Finally, we also summarize the results of promising clinical trials using biologicals targeting epithelial-derived cytokines in asthmatic patients. This article is protected by copyright. All rights reserved.

SARS-CoV-2-Induced TSLP Is Associated with Duration of Hospital Stay in COVID-19 Patients.

Thymic stromal lymphopoietin (TSLP) is an epithelium-derived pro-inflammatory cytokine involved in lung inflammatory responses. Previous studies show conflicting observations in blood TSLP in COVID-19, while none report SARS-CoV-2 inducing TSLP expression in bronchial epithelial cells. Our objective in this study was to determine whether TSLP levels increase in COVID-19 patients and if SARS-CoV-2 induces TSLP expression in bronchial epithelial cells. Plasma cytokine levels were measured in patients hospitalized with confirmed COVID-19 and age- and sex-matched healthy controls. Demographic and clinical information from COVID-19 patients was collected. We determined associations between plasma TSLP and clinical parameters using Poisson regression. Cultured human nasal (HNEpC) and bronchial epithelial cells (NHBEs), Caco-2 cells, and patient-derived bronchial epithelial cells (HBECs) obtained from elective bronchoscopy were infected in vitro with SARS-CoV-2, and secretion as well as intracellular expression of TSLP was detected by immunofluorescence. Increased TSLP levels were detected in the plasma of hospitalized COVID-19 patients (603.4 ± 75.4 vs 997.6 ± 241.4 fg/mL, mean ± SEM), the levels of which correlated with duration of stay in hospital (β: 0.11; 95% confidence interval (CI): 0.01-0.21). In cultured NHBE and HBECs but not HNEpCs or Caco-2 cells, TSLP levels were significantly elevated after 24 h post-infection with SARS-CoV-2 (p < 0.001) in a dose-dependent manner. Plasma TSLP in COVID-19 patients significantly correlated with duration of hospitalization, while SARS-CoV-2 induced TSLP secretion from bronchial epithelial cells in vitro. Based on our findings, TSLP may be considered an important therapeutic target for COVID-19 treatment.

The Value of IL-25, IL-33, and TSLP in Nasal Secretions as a Biomarker of Severity of Allergic Rhinitis in Children

Epithelial-derived cytokines such as IL-25, IL-33, and thymic stromal lymphopoietin (TSLP) play critical roles in allergic rhinitis (AR) inflammation. These cytokines are produced as the first line of defense against infection and irritation of the airway epithelium, are mainly involved in type 2 inflammatory responses, and are important regulators linking innate and adaptive immunity. We hypothesized that severity of allergic rhinitis (AR) in children would be associated with increased levels of these cytokines in nasal secretions.