The role of thymic stromal lymphopoietin in allergic inflammation and chronic obstructive pulmonary disease

Association between Serum Levels of Interleukin-25/Thymic Stromal Lymphopoietin and the Risk of Exacerbation of Chronic Obstructive Pulmonary Disease

Th2 inflammation is associated with various characteristics of patients with chronic obstructive pulmonary disease (COPD). In this study, we analyzed the COPD exacerbation risk associated with serum levels of interleukin (IL)-25/thymic stromal lymphopoietin (TSLP) and eosinophils. We studied the KOCOSS cohort, a multicenter COPD cohort created by 54 medical centers in South Korea. We extracted data collected between April 2012 and August 2020. We measured serum levels of TSLP and IL-25 in those who agreed to provide blood, and assessed exacerbation risk according to each. In all, 562 patients were enrolled. The IL-25-high group had a lower St. George's Respiratory Questionnaire score than others, and the TSLP-high group had a poorer exercise capacity than the TSLP-low group. There were no significant differences in the forced expiratory volume in 1 s (FEV1), the levels of Th2 inflammatory biomarkers, or the exacerbation histories between the two groups. The 3-year decline in FEV1 was not significantly affected by IL-25 or TSLP levels. In terms of 1-year exacerbation risk, individuals in the IL-25-high group were at lower risk for moderate-to-severe exacerbation than others. A high TSLP level was associated with a lower risk of severe exacerbation but only in the eosinophil-low group. Serum levels of IL-25 are negatively correlated with moderate-to-severe exacerbation risk in this cohort. A negative correlation between severe exacerbation risk and TSLP level was apparent only in the eosinophil-low group.

TSLP, IL-33, and IL-25: Not just for allergy and helminth infection

The release of cytokines from epithelial and stromal cells is critical for the initiation and maintenance of tissue immunity. Three such cytokines, thymic stromal lymphopoietin, IL-33, and IL-25, are important regulators of type 2 immune responses triggered by parasitic worms and allergens. In particular, these cytokines activate group 2 innate lymphoid cells, TH2 cells, and myeloid cells, which drive hallmarks of type 2 immunity. However, emerging data indicate that these tissue-associated cytokines are not only involved in canonical type 2 responses but are also important in the context of viral infections, cancer, and even homeostasis. Here, we provide a brief review of the roles of thymic stromal lymphopoietin, IL-33, and IL-25 in diverse immune contexts, while highlighting their relative contributions in tissue-specific responses. We also emphasize a biologically motivated framework for thinking about the integration of multiple immune signals, including the 3 featured in this review.

Short isoform thymic stromal lymphopoietin reduces inflammation and aerobic glycolysis of asthmatic airway epithelium by antagonizing long isoform thymic stromal lymphopoietin

Background

Up-regulation of aerobic glycolysis has been reported as a characterization of asthma and facilitates airway inflammation. We has been previously reported that short isoform thymic stromal lymphopoietin (sTSLP) could reduce inflammation in asthmatic airway epithelial cells. Here we wanted to investigate whether the inhibition of sTSLP on asthma is related to aerobic glycolysis.

Methods

Asthmatic model was established in challenging Male BALB/c mice and 16-HBE (human bronchial epithelial) cell line with house dust mite (HDM). Indicators of glycolysis were assessed to measure whether involve in sTSLP regulating airway epithelial cells inflammation in asthmatic model in vivo and in vitro.

Results

sTSLP decreased inflammation of asthmatic airway and aerobic glycolysis in mice. HDM or long isoform thymic stromal lymphopoietin (lTSLP) promoted HIF-1α expression and aerobic glycolysis by miR-223 to target and inhibit VHL (von Hippel-Lindau) expression 16-HBE. Inhibition of aerobic glycolysis restrained HDM- and lTSLP-induced inflammatory cytokines production. sTSLP along had almost no potential to alter aerobic glycolysis of 16-HBE. But sTSLP decreased LDHA (lactate dehydrogenase A) and LD (Lactic acid) levels in BALF, and HIF-1α and LDHA protein levels in airway epithelial cells of asthma mice model. lTSLP and sTSLP both induced formation of TSLPR and IL-7R receptor complex, and lTSLP obviously facilitated phosphorylation of JAK1, JAK2 and STAT5, while sTSLP induced a little phosphorylation of JAK1 and STAT5.

Conclusion

We identified a novel mechanism that lTSLP could promote inflammatory cytokines production by miR-223/VHL/HIF-1α pathway to upregulate aerobic glycolysis in airway epithelial cells in asthma. This pathway is suppressed by sTSLP through occupying binding site of lTSLP in TSLPR and IL-7R receptor complex.

Involvement of Neuro-Immune Interactions in Pruritus With Special Focus on Receptor Expressions

Pruritus is a common, but very challenging symptom with a wide diversity of underlying causes like dermatological, systemic, neurological and psychiatric diseases. In dermatology, pruritus is the most frequent symptom both in its acute and chronic form (over 6 weeks in duration). Treatment of chronic pruritus often remains challenging. Affected patients who suffer from moderate to severe pruritus have a significantly reduced quality of life. The underlying physiology of pruritus is very complex, involving a diverse network of components in the skin including resident cells such as keratinocytes and sensory neurons as well as transiently infiltrating cells such as certain immune cells. Previous research has established that there is a significant crosstalk among the stratum corneum, nerve fibers and various immune cells, such as keratinocytes, T cells, basophils, eosinophils and mast cells. In this regard, interactions between receptors on cutaneous and spinal neurons or on different immune cells play an important role in the processing of signals which are important for the transmission of pruritus. In this review, we discuss the role of various receptors involved in pruritus and inflammation, such as TRPV1 and TRPA1, IL-31RA and OSMR, TSLPR, PAR-2, NK1R, H1R and H4R, MRGPRs as well as TrkA, with a focus on interaction between nerve fibers and different immune cells. Emerging evidence shows that neuro-immune interactions play a pivotal role in mediating pruritus-associated inflammatory skin diseases such as atopic dermatitis, psoriasis or chronic spontaneous urticaria. Targeting these bidirectional neuro-immune interactions and the involved pruritus-specific receptors is likely to contribute to novel insights into the underlying pathogenesis and targeted treatment options of pruritus.

Inhibition of NADPH Oxidase-Derived Reactive Oxygen Species Decreases Expression of Inflammatory Cytokines in A549 Cells

Various experimental models strongly support the hypothesis that airway inflammation can be caused by oxidative stress. Inflammatory airway diseases like asthma and COPD are characterized by higher levels of ROS and inflammatory cytokines. One of the sources of ROS is NADPH oxidase. Therefore, the aim of the study was to investigate influence of NADPH oxidase inhibition on the expression of IL-6, IL-8, TNF, TSLP, CD59, and PPAR-γ in vitro. A549 cells were incubated with apocynin in three concentrations (0.5 mg/ml, 1 mg/ml, and 3 mg/ml). Cells were trypsinized and RNA isolated after 1 h, 2 h, and 4 h of apocynin incubation at each concentration. Afterwards, reverse transcription was performed to evaluate mRNA expression using real-time PCR. The time-response and dose-response study showed that apocynin significantly influenced the relative expression of chosen genes (IL-6, IL-8, TNF, PPAR-γ, TSLP, and CD59). Apocynin decreased the mRNA expression of TNF-α at all concentrations used, and of IL-6 at concentrations of 1 and 3 mg/ml (p < 0.05). TSLP mRNA expression was also reduced by apocynin after 1 h and 2 h, and CD59 mRNA after 1 h, but only at the highest concentration. The expression of PPAR-γ was reduced after apocynin in the highest concentrations only (p < 0.05). The results might suggest that proinflammatory agents’ expression levels are strongly connected to the presence of oxidative stress generated by NADPH oxidase and this might be at least partially eliminated by anti-oxidative action. Apocynin, as an effective inhibitor of NADPH oxidase, seems to be useful in potential anti-oxidative and anti-inflammatory therapy.

Effects of cannabis oil extract on immune response gene expression in human small airway epithelial cells (HSAEpC): implications for chronic obstructive pulmonary disease (COPD)

BACKGROUND

Chronic obstructive pulmonary disease (COPD) is commonly associated with both a pro-inflammatory and a T-helper 1 (Th1) immune response. It was hypothesized that cannabis oil extract can alleviate COPD symptoms by eliciting an anti-inflammatory Th2 immune response. Accordingly, the effects of cannabis oil extract on the expression of 84 Th2 and related immune response genes in human small airways epithelial cells (HSAEpC) were investigated.

METHODS

HSAEpC from a single donor were treated with three dilutions of a standardized cannabis oil extract (1:400, 1:800 and 1:1600) along with a solvent control (0.25% [2.5 ul/ml] ethanol) for 24 h. There were four replicates per treatment dilution, and six for the control. RNA isolated from cells were employed in pathway-focused quantitative polymerase chain reaction (qPCR) microarray assays.

RESULTS

The extract induced significant (P < 0.05) changes in expression of 37 tested genes. Six genes (CSF2, IL1RL1, IL4, IL13RA2, IL17A and PPARG) were up-regulated at all three dilutions. Another two (CCL22 and TSLP) were up-regulated while six (CLCA1, CMA1, EPX, LTB4R, MAF and PMCH) were down-regulated at the 1:400 and 1:800 dilutions. The relationship of differentially-expressed genes of interest to biologic pathways was explored using the Database for Annotation, Visualization and Integrated Discovery (DAVID).

CONCLUSIONS

This exploratory investigation indicates that cannabis oil extract may affect expression of specific airway epithelial cell genes that could modulate pro-inflammatory or Th1 processes in COPD. These results provide a basis for further investigations and have prompted in vivo studies of the effects of cannabis oil extract on pulmonary function.

TRIAL REGISTRATION

NONE (all in vitro experiments).

The Role and Immunobiology of Eosinophils in the Respiratory System: a Comprehensive Review

The eosinophil is a fully delineated granulocyte that disseminates throughout the bloodstream to end-organs after complete maturation in the bone marrow. While the presence of eosinophils is not uncommon even in healthy individuals, these granulocytes play a central role in inflammation and allergic processes. Normally appearing in smaller numbers, higher levels of eosinophils in the peripheral blood or certain tissues typically signal a pathologic process. Eosinophils confer a beneficial effect on the host by enhancing immunity against molds and viruses. However, tissue-specific elevation of eosinophils, particularly in the respiratory system, can cause a variety of short-term symptoms and may lead to long-term sequelae. Eosinophils often play a role in more commonly encountered disease processes, such as asthma and allergic responses in the upper respiratory tract. They are also integral in the pathology of less common diseases including eosinophilic pneumonia, allergic bronchopulmonary aspergillosis, hypersensitivity pneumonitis, and drug reaction with eosinophilia and systemic symptoms. They can be seen in neoplastic disorders or occupational exposures as well. The involvement of eosinophils in pulmonary disease processes can affect the method of diagnosis and the selection of treatment modalities. By analyzing the complex interaction between the eosinophil and its environment, which includes signaling molecules and tissues, different therapies have been discovered and created in order to target disease processes at a cellular level. Innovative treatments such as mepolizumab and benralizumab will be discussed. The purpose of this article is to further explore the topic of eosinophilic presence, activity, and pathology in the respiratory tract, as well as discuss current and future treatment options through a detailed literature review.

Thymic Stromal Lymphopoietin Neutralization Inhibits the Immune Adjuvant Effect of Di-(2-Ethylhexyl) Phthalate in Balb/c Mouse Asthma Model

Di-(2-ethylhexyl) phthalate (DEHP), a commonly used plasticizer, has an adjuvant effect in combination with ovalbumin (OVA). The adjuvant effect of DEHP has already been verified in our previous studies. In this study, to further investigate whether thymic stromal lymphopoietin (TSLP) was involved in the DEHP-adjuvant effect, DEHP was administered through a daily gavage exposure route. Mice were sensitized with ovalbumin (OVA) to trigger allergic responses, and an anti-TSLP monoclonal antibody was used to neutralize the effect of TSLP. Biomarkers including cytokines in bronchoalveolar lavage fluid (BALF), serum total IgE and TSLP content in the lung were detected. In addition, airway hyperreactivity and lung sections were examined. Collectively, these data indicated a salient Th2 response which was characterized by the upregulation of Th2-type cytokines, such as interleukin 4 (IL-4), IL-5 and IL-13. Moreover, the eosinophil number in BALF and the eosinophil cationic protein (ECP) in the lung were seen to have increased significantly. However, neutralization of TSLP with an anti-TSLP mAb reversed the adjuvant effect of DEHP on airway inflammation, structural alterations in the airway wall and increased airway hyperresponsiveness (AHR) to methacholine induced by the OVA allergen, suggesting that TSLP was an effective target site for suppressing the adjuvant effect of DEHP co-exposure.

The potential role of some phytochemicals in recognition of mitochondrial damage-associated molecular patterns

Mitochondria are the source of damage-associated molecular patterns (DAMPs). DAMPs modulate responses to stress and trauma in animals, influencing the onset of many diseases. Dietary phytochemicals, which target various cellular molecules, are potential modulators of immunological status. In this review the existence of the possible impact of some plant-derived compounds with proven anti-cancer and anti-inflammatory properties (isothiocyanates and curcumin) on DAMPs recognition is highlighted. Special consideration is given to the mtDNA recognizing Toll-like receptor 9 and formyl peptide receptors. In the context of the phytochemicals action, the role of these receptors in epithelial homeostasis is also discussed.

Upregulated thymic stromal lymphopoietin receptor expression in children with asthma

BACKGROUND

Thymic stromal lymphopoietin (TSLP) plays an important role in pathogenesis in patients with asthma. However, the role of thymic stromal lymphopoietin receptor (TSLPR) and correlation with IL-7Rα and clinical severity in asthmatic or nonasthmatic children remain unclear. We investigated TSLPR and IL-7Rα mRΝΑ levels in asthma and nonasthma and assessed TSLPR expression in children who were sensitive to mites.

MATERIALS AND METHODS

We enrolled asthmatic and nonasthmatic children. To minimize the influence of allergy, we also divided participants into following 4 groups: nonallergic and nonasthmatic group (NN) (healthy children), allergic but nonasthmatic group (AN), nonallergic but asthmatic group (NA) and allergic asthmatic group (AA). We drew blood samples to check total IgE, allergen-specific IgE and TSLP and measured the expression of the TSLPR and IL-7Rα genes using reverse-transcription polymerase chain reaction (RT-PCR) and real-time PCR. Asthma symptom score was also recorded.

RESULTS

Thymic stromal lymphopoietin and TSLPR levels were found to be significantly higher in asthmatic than in nonasthmatic children. The levels of TSLP were found to be significantly different between AA and NN groups (P < 0·05). TSLPR expression in NA and AA groups was found to be significantly higher than in NN group (P < 0·05). TSLPR did not differ significantly between NA and AA groups. The TSLPR expression correlated strongly with IL-7Rα and weakly with mite-specific IgE. Clinical asthmatic severity of children was found to exert no influence on TSLPR level.

CONCLUSION

Thymic stromal lymphopoietin receptor might be a significant disease biomarker for asthma. The levels of TSLPR were found to be higher in asthmatic patients than in healthy children, but were found to be not different between allergic and nonallergic asthmatic patients.

Immunobiology of critical pediatric asthma

Asthma is a heterogeneous disease with numerous clinical phenotypes. Severe asthma constitutes about 10 % of all cases of asthma. There is significant geographic and regional variation in the incidence and severity of asthma. Other important factors include gender, ethnicity, living environment, lifestyle, socioeconomic class, and pathophysiology. These factors can often be identified as either genetic or environmental influences on asthma severity. The immune system derangements in severe asthma are poorly understood. Many molecules and cell types have been implicated in severe asthma, including neutrophils, airway epithelial cells, thymic stromal lymphopoietin, and even filaggrin. Recently, vitamin D has been thought to have a role in the severity of asthma. Aspirin exacerbated respiratory disease is an example of a phenotype that includes severe asthma as a feature. This suggests a role of leukotrienes or prostaglandins in the pathogenesis of severe asthma. Both the innate and adaptive immune system may play a role in the development of severe asthma. Besides filaggrin, other factors of the innate immune system, including TLR4 and TLR9 have been implicated in asthma. Airway epithelial cells possess pattern recognition receptors that recognize danger or pathogen-associated molecular patterns, and the result of binding of the ligand is the triggering of a signaling pathway that ultimately can lead to an activation of inflammatory mediators through the action of calcineurin and NF-κB. Components of the adaptive immune system, including TH2 and Th17 cells, have been implicated in the pathogenesis of asthma. The fact that so many molecules and cells may be variably involved in asthma patients, coupled with the presence of redundant pathways that lead to secretion of inflammatory mediators, make the development of effective drugs for the treatment of asthma extremely difficult. A better understanding of the heterogeneity and what drives this diversity on a genetic and epigenetic level will help to develop strategies for novel therapeutic agents or methods.

Higher TGF-β with lower CD124 and TSLP, but no difference in PAR-2 expression in bronchial biopsy of bronchial asthma patients in comparison with COPD patients

Chronic obstructive pulmonary disease (COPD) and bronchial asthma (BA) are 2 severe respiratory disorders with different predominated immunopathologies. There are several "novel molecules" from different families that are proposed as part of the etiopathogenesis of COPD and BA. Proteinase-activated receptor 2 (PAR-2), thymic stromal lymphoprotein (TSLP), interleukin-4 and its receptor (CD124), Yin-Yang 1 (YY1), and transforming growth factor beta (TGF-β) have been previously shown to be involved in the pathophysiology of both these diseases. We investigated PAR-2, TSLP, CD124 (interleukin-4R), TGF-β, and YY1 immunohistochemical expression in endobronchial and transbronchial biopsies from 22 BA patients and 20 COPD patients. Immunostaining for the above-mentioned antigens was quantified using a modified semiquantitative scoring system and statistically evaluated. The values of TGF-β in the epithelial cells (P=0.0007) and TGF-β in the submucosa (P=0.0075) were higher in the BA samples, whereas values of CD124 (P=0.0015) and TSLP (P=0.0106) were higher in the COPD samples. No statistically significant differences between the groups were recorded for PAR-2 and YY1. Airway inflammatory reaction diversity in BA and COPD seems to be disease specific; however, there are also shared mechanisms involved in the pathophysiology of both diseases.

Effect of thymic stromal lymphopoietin on MUC5B expression in human airway epithelial cells

Thymic stromal lymphopoietin (TSLP) is an interleukin 7-like cytokine and a potent factor for B- and T-cell growth and differentiation. Recent studies have demonstrated an association of TSLP with allergic and inflammatory airway diseases. However, no study on the effect of TSLP on expression of mucin genes in airway epithelial cells has been reported. Therefore, the effects and brief signaling pathways of TSLP on expression of mucin genes in human airway epithelial cells were investigated in this study. In mucin-producing human NCI-H292 airway epithelial cells and primary cultures of normal nasal epithelial cells, the effect and signaling pathway of TSLP on expression of mucin genes were investigated using reverse transcriptase-polymerase chain reaction (RT-PCR), real-time PCR, enzyme immunoassay, and immunoblot analysis with several specific inhibitors and small interfering RNA (siRNA). In human NCI-H292 airway epithelial cells, TSLP increased MUC5B expression. TSLP significantly activated phosphorylation of ERK1/2 and p38 mitogen-activated protein kinase (MAPK). U0126 (ERK1/2 MAPK inhibitor) and SB203580 (p38 MAPK inhibitor) significantly attenuated TSLP-induced MUC5B mRNA expression. Knockdown of ERK1, ERK2, and p38 MAPK by ERK1, ERK2, and p38 MAPK siRNA significantly blocked TSLP-induced MUC5B mRNA expression. In the primary cultures of normal nasal epithelial cells, TSLP significantly increased MUC5B mRNA expression, which was significantly attenuated after pretreatment with U0126 and SB203580. These results suggest that TSLP induces MUC5B expression via the ERK1/2 and p38 MAPK signaling pathway in human airway epithelial cells.

Innate immunity but not NLRP3 inflammasome activation correlates with severity of stable COPD

Background

In models of COPD, environmental stressors induce innate immune responses, inflammasome activation and inflammation. However, the interaction between these responses and their role in driving pulmonary inflammation in stable COPD is unknown.

Objectives

To investigate the activation of innate immunity and inflammasome pathways in the bronchial mucosa and bronchoalveolar lavage (BAL) of patients with stable COPD of different severity and control healthy smokers and non-smokers.

Methods

Innate immune mediators (interleukin (IL)-6, IL-7, IL-10, IL-27, IL-37, thymic stromal lymphopoietin (TSLP), interferon γ and their receptors, STAT1 and pSTAT1) and inflammasome components (NLRP3, NALP7, caspase 1, IL-1β and its receptors, IL-18, IL-33, ST2) were measured in the bronchial mucosa using immunohistochemistry. IL-6, soluble IL-6R, sgp130, IL-7, IL-27, HMGB1, IL-33, IL-37 and soluble ST2 were measured in BAL using ELISA.

Results

In bronchial biopsies IL-27+ and pSTAT1+ cells are increased in patients with severe COPD compared with control healthy smokers. IL-7+ cells are increased in patients with COPD and control smokers compared with control non-smokers. In severe stable COPD IL-7R+, IL-27R+ and TSLPR+ cells are increased in comparison with both control groups. The NALP3 inflammasome is not activated in patients with stable COPD compared with control subjects. The inflammasome inhibitory molecules NALP7 and IL-37 are increased in patients with COPD compared with control smokers. IL-6 levels are increased in BAL from patients with stable COPD compared with control smokers with normal lung function whereas IL-1β and IL-18 were similar across all groups.

Conclusions

Increased expression of IL-27, IL-37 and NALP7 in the bronchial mucosa may be involved in progression of stable COPD.

Novel identified receptors on mast cells

Mast cells (MC) are major participants in the allergic reaction. In addition they possess immunomodulatory roles in the innate and adaptive immune reactions. Their functions are modulated through a number of activating and inhibitory receptors expressed on their surface. This review deals with some of the most recently described receptors, their expression patterns, ligand(s), signal transduction mechanisms, possible cross-talk with other receptors and, last but not least, regulatory functions that the MC can perform based on their receptor expression in health or in disease. Where the receptor role on MC is still not clear, evidences from other hematopoietic cells expressing them is provided as a possible insight for their function on MC. Suggested strategies to modulate these receptors’ activity for the purpose of therapeutic intervention are also discussed.

Thymic stromal lymphopoietin exerts antimicrobial activities

Thymic stromal lymphopoietin (TSLP) is an interleukin-7-like cytokine expressed by epithelial cells and reported to be involved in allergic diseases and atopic eczema. The presence of several predicted α-helical regions in TSPL, a structure characterizing many classical antimicrobial peptides (AMPs), prompted us to investigate whether TSLP exerts antimicrobial activities. Recombinant human TSLP exerted antimicrobial activity, particularly against Gram-negative bacteria. Using synthetic overlapping peptide 20-mers of TSLP, it was demonstrated that the antimicrobial effect is primarily mediated by the C-terminal region of the protein. MKK34 (MKKRRKRKVTTNKCLEQVSQLQGLWRRFNRPLLK), a peptide spanning a C-terminal α-helical region in TSLP, showed potent antimicrobial activities, in physiological salt conditions and in the presence of human plasma. Fluorescent studies of peptide-treated bacteria, electron microscopy and liposome leakage models showed that MKK34 exerted membrane-disrupting effects comparable to those of the classical AMP LL-37. Moreover, TSLP was degraded into multiple fragments by staphylococcal V8 proteinase. One major antimicrobial degradation fragment was found to encompass the C-terminal antimicrobial region defined by the MKK34 peptide. We here describe a novel antimicrobial role for TSLP. The antimicrobial activity is primarily mediated by the C-terminal part of the protein. In combination with the previously known cytokine function of TSLP, our result indicates dual functions of the molecule and a previously unknown role in host defense.

Amorphous silica nanoparticles size-dependently aggravate atopic dermatitis-like skin lesions following an intradermal injection

Background

Due to the rising use of nanomaterials (NMs), there is concern that NMs induce undesirable biological effects because of their unique physicochemical properties. Recently, we reported that amorphous silica nanoparticles (nSPs), which are one of the most widely used NMs, can penetrate the skin barrier and induce various biological effects, including an immune-modulating effect. Thus, it should be clarified whether nSPs can be a risk factor for the aggravation of skin immune diseases. Thus, in this study, we investigated the relationship between the size of SPs and adjuvant activity using a model for atopic dermatitis.

Results

We investigated the effects of nSPs on the AD induced by intradermaly injected-mite antigen Dermatophagoides pteronyssinus (Dp) in NC/Nga mice. Ear thickness measurements and histopathological analysis revealed that a combined injection of amorphous silica particles (SPs) and Dp induced aggravation of AD in an SP size-dependent manner compared to that of Dp alone. In particular, aggravation was observed remarkably in nSP-injected groups. Furthermore, these effects were correlated with the excessive induction of total IgE and a stronger systemic Th2 response. We demonstrated that these results are associated with the induction of IL-18 and thymic stromal lymphopoietin (TSLP) in the skin lesions.

Conclusions

A particle size reduction in silica particles enhanced IL-18 and TSLP production, which leads to systemic Th2 response and aggravation of AD-like skin lesions as induced by Dp antigen treatment. We believe that appropriate regulation of nanoparticle physicochemical properties, including sizes, is a critical determinant for the design of safer forms of NMs.

Cytokine pathways in allergic disease

Cytokines are critical in allergic intercellular communication networks, and they contribute to disease pathology through the recruitment and activation of pro-inflammatory leukocytes and in chronic disease to pro-fibrotic/remodeling events. Th2 cytokines predominate primarily in mild to moderate allergic asthma, although clinical trials with inhibitors of IL-4 and IL-5 have not provided the robust efficacy observed in animal models of allergy. These results not only highlight the complexity of allergic disease, but they also point to the importance of other cytokine networks in driving pathology. The heterogeneous nature of the disease is emphasized by the fact that the Th2/Th1/Th17 cytokine balance can be influenced by the initiating allergic trigger. For example, the house dust mite allergen Der p 2 mimics the activity of MD-2 by presenting lipopolysaccharide to Toll-like receptor-4 for the activation of inflammatory genes including innate-type cytokines. Here we discuss the functions of the novel cytokine players, thymic stromal lymphopoetin (TSLP), IL-33, IL-25, and IL-9 and delineate nonredundant roles for IL-4 and IL-13 in allergic disease. Persistent efforts in the characterization of these and other cytokine networks will be essential for understanding the complex pathogenic mechanisms that underpin allergic disease and for guiding targeted therapeutic interventions.

IL-33 induces Th17-mediated airway inflammation via mast cells in ovalbumin-challenged mice

Allergic asthma is characterized by infiltration of eosinophils, elevated Th2 cytokine levels, airway hyperresponsiveness, and IgE. In addition to eosinophils, mast cells, and basophils, a variety of cytokines are also involved in the development of allergic asthma. The pivotal role of eosinophils in the progression of the disease has been a subject of controversy. To determine the role of eosinophils in the progression of airway inflammation, we sensitized and challenged BALB/c wild-type (WT) mice and eosinophil-deficient ΔdblGATA mice with ovalbumin (OVA) and analyzed different aspects of inflammation. We observed increased eosinophil levels and a Th2-dominant response in OVA-challenged WT mice. In contrast, eosinophil-deficient ΔdblGATA mice displayed an increased proportion of mast cells and a Th17-biased response following OVA inhalation. Notably, the levels of IL-33, an important cytokine responsible for Th2 immune deviation, were not different between WT and eosinophil-deficient mice. We also demonstrated that mast cells induced Th17-differentiation via IL-33/ST2 stimulation in vitro. These results indicate that eosinophils are not essential for the development of allergic asthma and that mast cells can skew the immune reaction predominantly toward Th17 responses via IL-33 stimulation.

Function and mechanisms of TSLP/TSLPR complex in asthma and COPD

Thymic stromal lymphopoietin (TSLP) is a key pro-allergic cytokine that has recently been linked to chronic airway diseases, such as asthma and chronic obstructive pulmonary disease (COPD). High levels of TSLP were detected in bronchial mucosa of asthma and COPD patients suggesting TSLP's biological role beyond a signature 'Th2-favoring' or 'pro-allergic cytokine'. Besides inflammatory cells, airway structural cells produce and are targets of TSLP suggesting a potential autocrine loop that may have a profound effect on local inflammatory response and airway remodelling. This review sums up diverse mechanisms that mediate TSLP/TSLP receptor-signalling network in chronic airway diseases.

A genome-wide meta-analysis of genetic variants associated with allergic rhinitis and grass sensitization and their interaction with birth order

BACKGROUND

Hay fever or seasonal allergic rhinitis (AR) is a chronic disorder associated with IgE sensitization to grass. The underlying genetic variants have not been studied comprehensively. There is overwhelming evidence that those who have older siblings have less AR, although the mechanism for this remains unclear.

OBJECTIVE

We sought to identify common genetic variant associations with prevalent AR and grass sensitization using existing genome-wide association study (GWAS) data and to determine whether genetic variants modify the protective effect of older siblings.

METHOD

Approximately 2.2 million genotyped or imputed single nucleotide polymorphisms were investigated in 4 large European adult cohorts for AR (3,933 self-reported cases vs 8,965 control subjects) and grass sensitization (2,315 cases vs 10,032 control subjects).

RESULTS

Three loci reached genome-wide significance for either phenotype. The HLA variant rs7775228, which cis-regulates HLA-DRB4, was strongly associated with grass sensitization and weakly with AR (P(grass) = 1.6 × 10(-9); P(AR) = 8.0 × 10(-3)). Variants in a locus near chromosome 11 open reading frame 30 (C11orf30) and leucine-rich repeat containing 32 (LRRC32), which was previously associated with atopic dermatitis and eczema, were also strongly associated with both phenotypes (rs2155219; P(grass) = 9.4 × 10(-9); P(AR) = 3.8 × 10(-8)). The third genome-wide significant variant was rs17513503 (P(grass) = 1.2 × 10(-8); PAR = 7.4 × 10(-7)) which was located near transmembrane protein 232 (TMEM232) and solute carrier family 25, member 46 (SLC25A46). Twelve further loci with suggestive associations were also identified. Using a candidate gene approach, where we considered variants within 164 genes previously thought to be important, we found variants in 3 further genes that may be of interest: thymic stromal lymphopoietin (TSLP), Toll-like receptor 6 (TLR6) and nucleotide-binding oligomerization domain containing 1 (NOD1/CARD4). We found no evidence for variants that modified the effect of birth order on either phenotype.

CONCLUSIONS

This relatively large meta-analysis of GWASs identified few loci associated with AR and grass sensitization. No birth order interaction was identified in the current analyses.

The regulation of thymic stromal lymphopoietin in gut immune homeostasis

Thymic stromal lymphopoietin is a novel IL-7-like cytokine that exerts immunomodulatory effects and is constitutively expressed by intestinal epithelial cells in response to commensal bacteria colonization. Thymic stromal lymphopoietin can directly or indirectly promote Th2 and Treg responses, and is believed to inhibit Th1 and Th17 responses and limit the expression of proinflammatory cytokines such as IL-17 and IFN-γ. In response to infection by enteric pathogens, intestinal epithelial cells upregulate thymic stromal lymphopoietin expression in order to generate balance between inflammation and immune clearance. Recently, however, aberrant expression of thymic stromal lymphopoietin has been associated with inflammatory bowel disease. Thus, we sought to examine the relationship between the TLSP-TSLPR pathway and inflammation in hopes of contributing to the search for a novel therapeutic target to treat a variety of inflammatory diseases, including inflammatory bowel disease.

Increased expression and role of thymic stromal lymphopoietin in nasal polyposis

Purpose

Nasal polyposis is a chronic inflammatory disease of the upper airways often associated with asthma and characterized by markedly increased numbers of eosinophils, Th2 type lymphocytes, fibroblasts, goblet cells and mast cells. Previous studies have shown elevated levels of thymic stromal lymphopoietin (TSLP) in atopic diseases like asthma, atopic dermatitis and mainly in animal models of allergic rhinitis (AR). Here, we investigated the expression of TSLP in nasal polyps from atopics and non-atopics in comparison with the nasal mucosa and its potential role in nasal polyposis.

Methods

Messenger RNA expression for TSLP, thymus and activation-regulated chemokine (TARC) and macrophage derived chemokine (MDC) in nasal polyps and nasal mucosa of atopics and non-atopics was analyzed by real time PCR. Immunoreactivity for TSLP in nasal polyps and in the nasal mucosa of patients with AR and non-allergic rhinitis (NAR) was analyzed by immunohistochemistry. Eosinophil counts was analyzed by Wright-Giemsa staining and nasal polyp tissue IgE, by ELISA.

Results

Messenger RNA expression for TSLP,TARC and MDC was markedly higher in nasal polyps as compared to the allergic nasal mucosa. Immunoreactivity for TSLP was detected in epithelial cells, endothelial cells, fibroblasts and inflammatory cells of the nasal mucosa and nasal polyps. The number of TSLP+ cells was significantly greater in the nasal mucosa of AR than NAR patients. The number of TSLP+ cells in nasal polyps from atopics was significantly greater than that of non-atopics and that in the allergic nasal mucosa. The number of TSLP+ cells correlated well with the number of eosinophils and the levels of IgE in nasal polyps.

Conclusions

The high expression of TSLP in nasal polyps and its strong correlation to eosinophils and IgE suggest a potential role for TSLP in the pathogenesis of nasal polyps by regulating the Th2 type and eosinophilic inflammation.

The role of thymic stromal lymphopoietin (TSLP) in allergic disorders

The importance of the epithelium in initiating and controlling immune responses is becoming more appreciated. For example, allergen contact first occurs at mucosal sites exposed to the external environment, such as the skin, airways and gastrointestinal tract. This exposure leads to the production of a variety of cytokines and chemokines that are involved in driving allergic inflammatory responses. One such product is thymic stromal lymphopoietin (TSLP). Recent studies, in both humans and mouse models, have implicated TSLP in the development and progression of atopy and atopic diseases. This review will discuss this work and place TSLP in the inflammatory cascade that leads to allergic disease.