Overexpression of thymic stromal lymphopoietin in allergic rhinitis

Basophils in pruritic skin diseases

Basophils are rare cells in the peripheral blood which have the capability to infiltrate into the skin. Invasion of basophils has been detected in pruritic skin diseases, including atopic dermatitis, bullous pemphigoid, chronic spontaneous urticaria and contact dermatitis. In the skin, basophils are important players of the inflammatory immune response, as they release Th2 cytokines, including interleukin (IL)-4 and IL-13, subsequently inducing the early activation of T-cells. Further, basophils release a multitude of mediators, such as histamine and IL-31, which both play an important role in the initiation of the pruritic response via activation of sensory nerves. Chronic pruritus significantly affects the quality of life and the working capability of patients, though its mechanisms are not fully elucidated yet. Since basophils and neurons share many receptors and channels, bidirectional interaction mechanisms, which drive the sensation of itch, are highlighted in this review.

Long non-coding RNA MALAT1 promotes Th2 differentiation by regulating microRNA-135b-5p/GATA-3 axis in children with allergic rhinitis

Allergic rhinitis (AR) threatens patient survival. CD4⁺ T cells play key roles in AR progression. Long non-coding RNAs (lncRNAs) are key regulators of cell differentiation. Therefore, we investigated the molecular mechanism of the lncRNA metastasis-associated lung adenocarcinoma transcript 1 (MALAT1) in AR. Expression levels of MALAT1, microRNA (miR)-135b-5p, interleukin-4 (IL-4), and GATA-binding protein 3 (GATA-3) in the nasal mucosa of AR patients were quantified. CD4⁺ T cells were isolated from the peripheral blood of healthy volunteers and treated with ovalbumin (OVA) and Th2 inducers. After MALAT1 and miR-135b-5p levels changed in CD4⁺ T cells, the proportion of IL-4-expressing cells and the levels of IL-4 and GATA-3 in OVA-induced CD4⁺ T cells were determined. Binding relationships among MALAT1, miR-135b-5p, and GATA-3 were predicted and verified. Rescue experiments were performed to confirm the role of the MALAT1/miR-135b-5p/GATA-3 axis in Th2 differentiation of CD4⁺ T cells. MALAT1, IL-4, and GATA-3 expression was upregulated, whereas miR-135b-5p expression was downregulated, in patients with AR. MALAT1 knockdown or miR-135b-5p overexpression in CD4⁺ T cells notably decreased the proportion of IL-4-expressing cells and downregulated GATA-3 and IL-4 expression in OVA-induced CD4⁺ T cells. MALAT1 and GATA-3 exhibited competitive binding toward miR-135b-5p. MALAT1 facilitated CD4⁺ T cell Th2 differentiation via the miR-135b-5p/GATA-3 axis. MALAT1 facilitated AR development by facilitating CD4⁺ T cell Th2 differentiation via the miR-135b-5p/GATA-3 axis. This study may provide guidance for clinical treatment of AR.

The Role of Airway Epithelial Cell Alarmins in Asthma

The airway epithelium is the first line of defense for the lungs, detecting inhaled environmental threats through pattern recognition receptors expressed transmembrane or intracellularly. Activation of pattern recognition receptors triggers the release of alarmin cytokines IL-25, IL-33, and TSLP. These alarmins are important mediators of inflammation, with receptors widely expressed in structural cells as well as innate and adaptive immune cells. Many of the key effector cells in the allergic cascade also produce alarmins, thereby contributing to the airways disease by driving downstream type 2 inflammatory processes. Randomized controlled clinical trials have demonstrated benefit when blockade of TSLP and IL-33 were added to standard of care medications, suggesting these are important new targets for treatment of asthma. With genome-wide association studies demonstrating associations between single-nucleotide polymorphisms of the TSLP and IL-33 gene and risk of asthma, it will be important to understand which subsets of asthma patients will benefit most from anti-alarmin therapy.

Thymic stromal lymphopoietin, skin barrier dysfunction, and the atopic march

OBJECTIVE

Atopic dermatitis often precedes the development of other atopic diseases, and the atopic march describes this temporal relationship in the natural history of these diseases. Although the pathophysiological mechanisms that underlie this relationship are poorly understood, epidemiologic and genetic data have suggested that the skin might be an important route of sensitization to allergens.

DATA SOURCES

Review of recent studies on the role of skin barrier defects in systemic allergen sensitization.

STUDY SELECTIONS

Recent publications on the relationship between skin barrier defects and expression of epithelial cell-derived cytokines.

RESULTS

Animal models have begun to elucidate on how skin barrier defects can lead to systemic allergen sensitization. Emerging data now suggest that epithelial cell-derived cytokines, such as thymic stromal lymphopoietin, drive the progression from atopic dermatitis to asthma and food allergy. Skin barrier defects can lead to induction of epithelial cell-derived cytokines, which in turn leads to the initiation and maintenance of allergic inflammation and the atopic march.

CONCLUSION

Development of new biologic drug targeting type 2 cytokines provides novel therapeutic interventions for atopic dermatitis.

The role of thymic stromal lymphopoietin in the development of chronic otitis media with effusion

PURPOSE

To investigate the effect of thymic stromal lymphopoietin on the development of chronic otitis media with effusion MATERIALS AND METHODS: This study was conducted on 40 patients who had adenoidectomy operation. The objects were divided into two groups. Group 1; adenoidectomy with chronic serous otitis media, group 2; adenoidectomy without chronic serous otitis media. Serum and tissue thymic stromal lymphopoietin levels were measured by ELISA. Serum and tissue TLSP levels, mast cell count, adenoid size were compared between the groups.

RESULTS

Twenty-four (60%) of patients were female and 16 (40%) were male. Twenty patients (55%) had adenoid hypertrophy with chronic serous otitis media, and 18 (45%) had adenoid hypertrophy without chronic serous otitis media. The mean age of the patients was 6.21 ± 2.31 years. The mean mast cell count was significantly higher in group 1 compared with group 2 (p = 0.017). The mean tissue thymic stromal lymphopoietin measurement was also significantly higher in group 1 than group 2 (p = 0.023). However, there was no significant difference in regards to serum levels between the groups (p = 0.480).

CONCLUSION

The number of mast cells as well as thymic stromal lymphopoietin levels in the adenoids of children was significantly high in the chronic serous otitis media patients. The release of thymic stromal lymphopoietin from the adenoid tissue plays a role in initiating and maintaining a local inflammatory reaction in the eustachian tube that may lead eventually to middle ear effusion in non-atopic patients.

Dectin-1 Controls TSLP-Induced Th2 Response by Regulating STAT3, STAT6, and p50-RelB Activities in Dendritic Cells

The epithelium-associated cytokine thymic stromal lymphopoietin (TSLP) can induce OX40L and CCL17 expression by myeloid dendritic cells (mDCs), which contributes to aberrant Th2-type immune responses. Herein, we report that such TSLP-induced Th2-type immune response can be effectively controlled by Dectin-1, a C-type lectin receptor expressed by mDCs. Dectin-1 stimulation induced STAT3 activation and decreased the transcriptional activity of p50-RelB, both of which resulted in reduced OX40L expression on TSLP-activated mDCs. Dectin-1 stimulation also suppressed TSLP-induced STAT6 activation, resulting in decreased expression of the Th2 chemoattractant CCL17. We further demonstrated that Dectin-1 activation was capable of suppressing ragweed allergen (Amb a 1)-specific Th2-type T cell response in allergy patients ex vivo and house dust mite allergen (Der p 1)-specific IgE response in non-human primates in vivo. Collectively, this study provides a molecular explanation of Dectin-1-mediated suppression of Th2-type inflammatory responses and suggests Dectin-1 as a target for controlling Th2-type inflammation.

Associations among phthalate exposure, DNA methylation of TSLP, and childhood allergy

BACKGROUND

Dysregulation of thymic stromal lymphopoietin (TSLP) expressions is linked to asthma and allergic disease. Exposure to phthalate esters, a widely used plasticizer, is associated with respiratory and allergic morbidity. Dibutyl phthalate (DBP) causes TSLP upregulation in the skin. In addition, phthalate exposure is associated with changes in environmentally induced DNA methylation, which might cause phenotypic heterogeneity. This study examined the DNA methylation of the TSLP gene to determine the potential mechanism between phthalate exposure and allergic diseases.

RESULTS

Among all evaluated, only benzyl butyl phthalate (BBzP) in the settled dusts were negatively correlated with the methylation levels of TSLP and positively associated with children's respiratory symptoms. The results revealed that every unit increase in BBzP concentration in the settled dust was associated with a 1.75% decrease in the methylation level on upstream 775 bp from the transcription start site (TSS) of TSLP (β =  - 1.75, p = 0.015) after adjustment for child's sex, age, BMI, parents' smoking status, allergic history, and education levels, PM_2.5, formaldehyde, temperature; and relative humidity. Moreover, every percentage increase in the methylation level was associated with a 20% decrease in the risk of morning respiratory symptoms in the children (OR 0.80, 95% CI 0.65-0.99).

CONCLUSIONS

Exposure to BBzP in settled dust might increase children's respiratory symptoms in the morning through decreasing TSLP methylation. Therefore, the exposure to BBzP should be reduced especially for the children already having allergic diseases.

Combined Treatment With H1 and H4 Receptor Antagonists Improves Th2 Inflammatory Responses in the Nasal Mucosa of Allergic Rhinitis Rats

BACKGROUND

Histamine H1 receptor (H1R) antagonists are the first-line drugs for the treatment of allergic rhinitis (AR) at present. Emerging evidence supports an important role of histamine H4 receptor (H4R) in allergic diseases. However, information regarding the effects of combined treatment with H1 and H4 receptor antagonists in AR is limited.

OBJECTIVES

We aimed to assess the effects of combined treatment with H1R and H4R antagonists on Th2 inflammatory responses in the nasal mucosa of AR rats.

METHODS

Sprague Dawley rats were sensitized with ovalbumin and treated with H1R antagonist desloratadine or/and H4R antagonist JNJ7777120. Western blotting was used to assay the phenotypic markers of mature dendritic cells in the nasal mucosa, including major histocompatibility complex class II (MHC-II) and co-stimulatory molecules CD80, CD86 and OX40 ligand (OX40L). Th2 inflammatory cytokines including interleukin-4, 5 and 13 in nasal lavage fluids were determined by using enzyme-linked immunoassay.

RESULTS

The treatment with desloratadine alone down-regulated the CD86 expression, and decreased the production of Th2 cytokines, but had no impact on the expression of MHC-II, CD80 and OX40L. The administration of NJ7777120 alone reduced the levels of CD86, OX40L and Th2 cytokines, whereas MHC-II and CD80 expression was unaffected. The combination of desloratadine and JNJ7777120 showed more significant synergistic therapeutic effects than monotherapy.

CONCLUSION

H4R antagonist acted synergistically with H1R antagonist to reduce Th2 inflammatory responses by down-regulating CD86 and OX40L expression in the nasal mucosa of AR rats. The combination with H1R and H4R antagonists might be a new strategy for AR treatment.

Interleukin-17A up-regulates thymic stromal lymphopoietin production by nasal fibroblasts from patients with allergic rhinitis

PURPOSE

Emerging evidence has shown that interleukin (IL)-17A is implicated in the pathogenesis of allergic rhinitis (AR). Thymic stromal lymphopoietin (TSLP) orchestrates the immune response toward a Th2 phenotype. Although increased TSLP is found in AR, the contribution of IL-17A in TSLP production by nasal fibroblasts is not well understood. We aimed to investigate the effect and mechanism of IL-17A on TSLP production by human nasal fibroblasts (HNFs) from AR patients.

METHODS

HNFs from AR patients were cultured and stimulated with IL-17A in the absence or presence of a Janus kinase (JAK) 2 or JAK1/3 inhibitor. Western blotting was used to assay phosphorylated signal transducer and activator of transcription 3 (p-STAT3) and nuclear factor-kappa B (NF-κB) p65 in HNFs. The TSLP expression in the cells and culture supernatants was evaluated by real-time polymerase chain reaction and enzyme-linked immunoassay.

RESULTS

Stimulation with IL-17A induced STAT3 phosphorylation, which was inhibited by the pretreatment with JAK2 inhibitor AZD1480 or JAK1/3 inhibitor tofacitinib. IL-17A promoted the nuclear translocation of NF-κBp65 protein, leading to increased TSLP production, while the pre-incubation with AZD1480 prior to IL-17A attenuated these effects. However, the pre-incubation with tofacitinib before IL-17A stimulation had no impact on the expression of NF-κBp65 and TSLP.

CONCLUSIONS

IL-17A up-regulated TSLP production by HNFs through JAK2/NF-κB pathway. Although IL-17A induced STAT3 activation through JAK1/2/3, IL-17A-mediated TSLP expression was not dependent on STAT3 signaling. These observations would provide mechanistic insight into therapeutic strategies to improve the immune and inflammation associated with Th17A in the management of AR.

Synergistic relationship between TSLP and IL-33/ST2 signaling pathways in allergic rhinitis and the effects of hypoxia

BACKGROUND

The World Health Organization (WHO) has noted that allergic diseases are a major health problem of the 21st century. Allergic rhinitis (AR) is a type I allergic disease characterized by nasal mucosa and immune system abnormalities. AR is mediated by various inflammatory cells and is mainly characterized by altered secretion of cytokines. Thymic stromal lymphopoietin (TSLP) and the interleukin-33/stimulation-expressed gene 2 (IL-33/ST2) signaling pathway are cytokines that play pivotal roles in many inflammatory responses and allergic reactions. There have been reports of interactions between the 2 pathways in many diseases. Hypoxia is a common pathologic manifestation of AR. The aim of this study was to explore the relationship and expressions and biologic functions of TSLP and IL-33/ST2 in AR, and also to determine the effects of hypoxia on these cytokines.

METHODS

The rat nasal mucosal epithelium was obtained from Wistar rats. Cells were cultured in groups under hypoxia and normoxia conditions. Identification of rat nasal epithelial cell (RNEpC) and protein expressions was done by immunohistochemistry and immunofluorescence methods. Cell proliferation and migration were examined using the cell counting kit-8 (CCK-8) and Transwell kit. Detection of apoptosis was tested using a fluorescence apoptosis kit. Enzyme-linked immunoassay (ELISA) and Western blot analysis ELISA were used to measure cell secretion and protein expressions. For these experiments, TSLP was knocked down by lentivirus transfection and IL-33 blocked with its antagonist.

RESULTS

TSLP, IL-33, and ST2 expressions were significantly higher in nasal mucosa epithelial cells from AR rats than in those from control rats. Hypoxia further promoted their expression. Increased TSLP and IL-33/ST2 promoted cell proliferation, inhibited cell apoptosis, and enhanced cell migration. In addition, the downregulation of TSLP expression effectively attenuated expression of the IL-33/ST2 axis and, through use of IL-33 antagonists, could also reduce TSLP expression, a synergistic effect more obvious under hypoxia.

CONCLUSION

Our data indicate that TSLP and IL-33/ST2 signaling pathways interact with each other in the pathogenesis and pathologic development of AR. TSLP inhibition is a key factor in AR treatment. Inhibiting hypoxia-induced pathologic processes could represent a therapeutic effect by inhibiting IL-33/ST2 expression via downregulating TSLP.

Group 2 Innate Lymphoid Cells in Airway Diseases

Group 2 innate lymphoid cells (ILC2s) are increasingly recognized as a key controller of type 2 inflammation, and are well known to be highly elevated in human airway type 2 inflammatory diseases including allergic rhinitis, chronic rhinosinusitis with nasal polyps, and asthma. ILC2-mediated production of type 2 cytokines initiates and amplifies airway inflammation via activation of eosinophils, B cells, mast cells, macrophages, fibroblasts, and epithelial cells in these diseases. ILC2s require at least three major signals to fully activate and robustly produce type 2 cytokines. IL-1 family cytokines (IL-1β, IL-18, IL-33), IL-25, and TNF superfamilies (TNF, TL1A, GITR-L, RANK-L) activate the NF-κB and AP-1 pathways that initiate production of IL-5 and IL-13. Lipid mediators (LTC4, LTD4, PGD2) and neuropeptide NMU promote production of IL-4 through the NFAT pathway. IL-2 and IL-7 family cytokines (IL-2, IL-7, IL-9, TSLP) activate the STAT5 pathway that induces survival of ILC2s and enhances cytokine production. The activation of STAT5 is necessary to potently induce cytokine- and lipid mediator-mediated production of type 2 cytokines. Inhibitory pathways for ILC2s have also become clearer. Type I and II interferons and IL-27 inhibit ILC2 functions through the activation of STAT1. Suppression mediated via β2-adrenergic receptor agonists, PGE2, and PGI2 occurs through cAMP and PKA. Glucocorticoid, testosterone, IL-10, and TGF-β are also able to inhibit ILC2-mediated production of type 2 cytokines. Blockage of ILC2 activators, activation of inhibitory pathways of ILC2s, and suppression of ILC2-mediated pathways including type 2 cytokines (IL-5, IL-13, IL-4Ra) may become therapeutic strategies for airway type 2 inflammatory diseases.

Role of innate lymphoid cells in allergic diseases

Background: Over the past decade, there has been increasing interest and research into understanding the type 2 immune responses by the epithelium-derived cytokines interleukin (IL) 33, IL-25, and thymic stromal lymphopoietin. Innate lymphoid cells (ILC) are a unique family of effector immune cells that functionally resemble T cells but lack clonal distributed antigen receptors. Group 2 ILCs, ILC2s, are known for their capability to secrete proallergic cytokines, including IL-5 and IL-13. ILC2s are enriched at mucosal barriers in lung, gut, and skin, and their activation has been associated with a variety of allergic disorders. Objective: To study the role of ILC2 in different allergic disorders, including allergic rhinitis, asthma, atopic dermatitis, and food allergies. Methods: A MEDLINE search was performed for articles that reported on ILC2 in allergic disorders, including allergic rhinitis, asthma, atopic dermatitis, and food allergies. Results: A review of the literature revealed an important role of ILC2 in various allergic disorders. Conclusion: Identification of ILC2s in patients with allergic rhinitis, asthma, and atopic dermatitis indicates that these cells may represent a new therapeutic target. In this review, we discussed the current understanding of ILC2 biology and its function and regulation in various allergic diseases.

Basophils from allergic rhinitis patients show allergen-specific upregulation of thymic stromal lymphopoietin receptor

BACKGROUND

An allergic rhinitis (AR) diagnosis is based on typical nasal symptoms and allergen sensitization testing. However, it is sometimes difficult to distinguish AR from non-AR, and it is especially difficult to identify the causal allergen for immunotherapy of patients with AR.

OBJECTIVE

To identify differences among patients with AR, subjects with asymptomatic sensitization (AS), and subjects without sensitization (NS) that could facilitate the diagnosis of AR.

METHODS

We used RNA sequencing to examine differential gene expression in unstimulated and allergen-stimulated peripheral basophils from participants with NS, AS, and AR. We selected genes that were upregulated after allergen stimulation and showed differences in expression in patients with AR compared with subjects with AS and NS. Basophil surface expression of 1 gene product was examined by flow cytometry. The usefulness of gene expression in the diagnosis of AR was examined with receiver operating characteristic curves.

RESULTS

Expression of cytokine receptor-like factor 2 and its product, thymic stromal lymphopoietin receptor (TSLPR), was significantly increased in basophils of patients with AR after allergen stimulation. A significantly larger percentage of TSLPR-positive cells was observed after allergen-specific stimulation of basophils from patients with AR compared with subjects with AS. Basophil TSLPR expression was as good as or better than CD203c expression in discriminating between patients with AR and subjects with AS, as judged by receiver operating characteristic curves.

CONCLUSION

Our data suggest that TSLPR expression on basophils was specifically upregulated by allergen stimulation and might be useful for the identification of the causative allergen in patients with AR.

Airway innate lymphoid cells in the induction and regulation of allergy

The recent discovery of innate lymphoid cells has revolutionized our understanding of the pathogenesis of immune diseases including allergy and asthma. Innate lymphoid cells (ILCs) are a heterogeneous collection of lymphocytes that lack antigen-specificity (non-T, non-B cells) and potently produce characteristic cytokines of T cell subsets (Th1, Th2, Th17). ILCs are divided into group 1 (ILC1s), group 2 (ILC2s), or group 3 (ILC3s). Similar to Th2 cells, ILC2s produce IL-4, IL-5, and IL-13, among others, and are present in increased numbers in samples from patients with many allergic disorders including asthma and chronic rhinosinusitis (CRS). Animal models have identified that ILC2s contribute to eosinophilic tissue infiltration, airway hyperresponsiveness, mucus production, as well as coordinate adaptive immune responses. Finally, recent studies support regulation of ILC2s by neuro-immune mechanisms as well as demonstrate a significant degree of plasticity between ILC subsets that may impact the immune responses in asthma and allergic airway diseases. Here, we review the current literature on ILC2s in human asthma and allergic airway diseases, as well as highlight some recent mechanistic insights into ILC2 function from in vitro studies and in vivo animal models.

Expression and Regulation of Thymic Stromal Lymphopoietin and Thymic Stromal Lymphopoietin Receptor Heterocomplex in the Innate-Adaptive Immunity of Pediatric Asthma

Asthma is a chronic inflammatory disease affecting the airway, and it is characterized by a wheezing breathing sound, variable airflow obstruction and the presence of inflammatory cells in the submucosa of the bronchi. Viral infection, pollutants and sensitivity to aeroallergens damage the epithelium from childhood, which causes asthma. The pathogenesis of asthma includes pathways of innate stimulation by environmental microbes and irritant pathogens. Damaged epithelial cells produce thymic stromal lymphopoietin (TSLP) and stimulate myeloid dendritic cell maturation through the thymic stromal lymphopoietin receptor (TSLPR) heterocomplex. TSLP-activated myeloid dendritic cells promote naive CD4⁺ T cells to differentiate into T helper type 2 (Th2) phenotype CD4⁺ T cells. Re-exposure to allergens or environmental stimuli causes an adaptive immune response. TSLP-activated dendritic cells expressing the OX40 ligand (OX40L; CD252) trigger naive CD4⁺ T cells to differentiate into inflammatory Th2 effector cells secreting the cytokines interleukin-4, 5, 9, and 13 (IL-4, IL-5, IL-9 and IL-13), and the dendritic cells (DCs) promote the proliferation of allergen-specific Th2 memory cells. Allergen presentation by Th2 cells through its interaction with their receptors in the presence of major histocompatibility complex (MHC) class II on B cells and through costimulation involving CD40 and CD40L interactions results in immunoglobulin class switching from IgM to IgE. DCs and other blood cell subsets express the TSLPR heterocomplex. The regulatory mechanism of the TSLPR heterocomplex on these different cell subsets remains unclear. The TSLPR heterocomplex is composed of the IL-7Rα chain and TSLPR chain. Moreover, two isoforms of TSLP, short isoform TSLP (sfTSLP) and long isoform TSLP (lfTSLP), have roles in atopic and allergic development. Identifying and clarifying the regulation of TSLPR and IL-7Rα in pediatric asthma are still difficult, because the type of blood cell and the expression for each blood cell in different stages of atopic diseases are poorly understood. We believe that further integrated assessments of the regulation mechanism of the TSLP–TSLPR heterocomplex axis in vitro and in vivo can provide a faster and earlier diagnosis of pediatric asthma and promote the development of more effective preventive strategies at the onset of allergies.

Cysteine ameliorates allergic inflammatory reactions by suppressing thymic stromal lymphopoietin production in activated human mast cells

Thymic stromal lymphopoietin (TSLP) derived by mast cells is recognized as a critical factor in many allergic inflammatory disorders. Cysteine is a well-known amino acid which exhibits anti-inflammatory activities. However, the effect and mechanism of cysteine on TSLP production have not been investigated. Thus, we hypothesized that cysteine may regulate TSLP production from mast cells. To test this hypothesis, the anti-inflammatory effects and signaling pathways of cysteine were investigated in phorbol 12-myristate 13-acetate 4 and calcium ionophore A23187 (PMACI)-stimulated human mast cell line HMC-1. Cysteine dramatically attenuated the levels of TSLP of both mRNA and protein without cytotoxicity. Moreover, cysteine suppressed caspase-1 activation and nuclear factor-κB translocation. The phosphorylation of p38 and c-Jun N-terminal kinase was downregulated in all cases in PMACI-stimulated HMC-1 cells treated with cysteine. In addition, cysteine decreased PMACI-induced proinflammatory cytokines in terms of both protein and mRNA levels. In conclusion, cysteine regulates TSLP production by blocking caspase-1, nuclear factor-κB, p38, and c-Jun N-terminal kinase-dependent pathways in activated HMC-1 cells, suggesting its potential as a regulator of allergic inflammatory diseases.

Treatment of allergic rhinitis with CpG oligodeoxynucleotides alleviates the lower airway outcomes of combined allergic rhinitis and asthma syndrome via a mechanism that possibly involves in TSLP

PURPOSE

Thymic stromal lymphopoietin (TSLP) is a critical regulator of immune responses associated with Th2 cytokine-mediated inflammation. Intranasal administration of oligodeoxynucleotides with CpG motifs (CpG-ODNs) might improve lower airway outcomes of combined allergic rhinitis and asthma syndrome (CARAS), but the inherent mechanisms of CpG-ODNs are not well defined. This study investigated whether CpG-ODNs treated to upper airway could reduce lower airway TSLP expression as well as whether this reduction could contribute to the alleviation of lower allergic inflammation and airway hyper-reactivity (AHR) in CARAS mice.

MATERIALS AND METHODS

Ovalbumin (OVA)-sensitized BALB/c mice were intranasal OVA exposure three times a week for 3 weeks. CpG-ODNs or an anti-TSLP mAb was administered to a subset of these mice 1 hour after intranasal OVA challenge, followed by 5 days of OVA aerosol challenge. The resulting immunological variables, nasal symptoms, and nasal mucosa and lung tissues pathology were evaluated. TSLP production in the lung tissues and bronchoalveolar lavage fluid (BALF) were determined by RT-PCR, western blotting or enzyme-linked immunosorbent assay.

RESULTS

The CARAS mice exhibited overexpression of TSLP in the lung tissues and BALF, and also demonstrated significant increases in BALF and splenocyte Th2-associated cytokine production, serum OVA-specific IgE, nose and lung pathologies, and AHR. Intranasal administration of CpG-ODNs restored TSLP in the lower airway, and it significantly reduced the following parameters: Th2-type cytokine production levels; the percentage of eosinophils in the BALF; IL-4 and IL-5 concentrations in the supernatants of cultured splenic lymphocytes; serum OVA-specific IgE; peribronchial inflammation score in the lungs; and nose pathology and nasal symptoms. Similar results were obtained when the CARAS mice were treated with an anti-TSLP mAb to block intranasal TSLP activity.

CONCLUSIONS

Treatment with intranasal CpG-ODNs improves lower airway immunological variable outcomes in the CARAS model via a mechanism that possibly involves in suppressing pulmonary TSLP-triggered allergic inflammation.

Atopic Dermatitis Studies through In Vitro Models

Atopic dermatitis (AD) is a complex inflammatory skin condition that is not fully understood. Epidermal barrier defects and Th2 immune response dysregulations are thought to play crucial roles in the pathogenesis of the disease. A vicious circle takes place between these alterations, and it can further be complicated by additional genetic and environmental factors. Studies investigating in more depth the etiology of the disease are thus needed in order to develop functional treatments. In recent years, there have been significant advances regarding in vitro models reproducing important features of AD. However, since a lot of models have been developed, finding the appropriate experimental setting can be difficult. Therefore, herein, we review the different types of in vitro models mimicking features of AD. The simplest models are two-dimensional culture systems composed of immune cells or keratinocytes, whereas three-dimensional skin or epidermal equivalents reconstitute more complex stratified tissues exhibiting barrier properties. In those models, hallmarks of AD are obtained, either by challenging tissues with interleukin cocktails overexpressed in AD epidermis or by silencing expression of pivotal genes encoding epidermal barrier proteins. Tissue equivalents cocultured with lymphocytes or containing AD patient cells are also described. Furthermore, each model is placed in its study context with a brief summary of the main results obtained. In conclusion, the described in vitro models are useful tools to better understand AD pathogenesis, but also to screen new compounds in the field of AD, which probably will open the way to new preventive or therapeutic strategies.

The potential protective role of taurine against experimental allergic inflammation

AIMS

Taurine has been widely evaluated as a potential therapeutic agent in chronic inflammatory disorders and various infections. However, the potential role of taurine in regulating allergic inflammatory responses is currently unknown.

MATERIALS AND METHODS

The present study was designed to evaluate the in vitro effects of taurine on the levels of thymic stromal lymphopoietin (TSLP) and other pro-inflammatory cytokines and activation of caspase-1 and nuclear factor (NF)-κB as well as the phosphorylations of c-Jun N-terminal kinase (JNK) and p38 in phorbol 12-myristate 13-acetate and calcium ionophore A23187 (PMACI)-triggered human mast cell line, HMC-1 cells. Furthermore, we assessed the therapeutic effects of taurine on ovalbumin (OVA)-induced allergic rhinitis (AR) animal models.

KEY FINDINGS AND SIGNIFICANCE

Here, the obtained results showed that taurine dose-dependently inhibited the production and mRNA expression of TSLP and pro-inflammatory cytokines in HMC-1 cells exposed to PMACI. Taurine attenuated the phosphorylation of JNK and p38 in activated HMC-1 cells. Moreover, taurine brought a significant inhibition of the activities of NF-κB and caspase-1. In an OVA-induced AR animal model, the increased levels of nose rubbing, histamine, immunoglobulin E, TSLP, and interleukin IL-1β were dramatically reduced by the administration of taurine. In summary, taurine could serve as potential novel remedy of allergic inflammatory disorders.

Thymic Stromal Lymphopoietin: To Cut a Long Story Short

Thymic stromal lymphopoietin (TSLP) was identified more than 20 years ago as a secreted factor of a mouse thymic stromal cell line; later, a human orthologue was also identified. The signaling pathway triggered by TSLP has been extensively studied, and upregulation of the cytokine itself is linked to the pathogenesis of numerous Th2-related diseases, including atopic dermatitis, asthma, allergic responses, as well as certain types of cancers. On the other hand, TSLP mediates several immune homeostatic functions in both the gut and the thymus. Thus, a paradox occurs; why is TSLP homeostatic in certain tissues and a hallmark of exacerbated Th2 responses in the aforementioned pathologies? We and others have recently shown that in humans a novel isoform exists; this is a shorter isoform of TSLP whose expression is constitutive and controlled by a separate promoter. Short TSLP isoform mediates the homeostatic functions, whereas the long isoform is expressed at low/undetectable level at steady state and upregulated during inflammation in several tissues. Here we review the most recent data concerning the differential expression of the 2 isoforms and provide a potential explanation to the paradox. TSLP is regarded as a promising target for treatment of relevant pathologies, with a number of clinical trials already underway. It is important to design new strategies aimed at leaving intact the homeostatic effects of the short isoform while targeting the inflammatory effects of the long isoform.

TSLP receptor is not essential for house dust mite-induced allergic rhinitis in mice

TSLP induces Th2 cytokine production by Th2 cells and various other types of cells, thereby contributing to Th2-type immune responses and development of allergic disorders. We found that house dust mite (HDM) extract induced TSLP production by nasal epithelial cells, suggesting that TSLP may be involved in development of HDM-induced allergic rhinitis (AR). To investigate that possibility in greater detail, wild-type and TSLP receptor-deficient (TSLPR-/-) mice on the C57BL/6J background were repeatedly treated intranasally with HDM extract. The frequency of sneezing, numbers of eosinophils and goblet cells, thickness of submucosal layers, serum levels of total IgE and HDM-specific IgG1, and levels of IL-4, IL-5 and IL-13 in the culture supernatants of HDM-stimulated LN cells were comparable in the two mouse strains. Those findings indicate that, in mice, TSLPR is not crucial for development of HDM-induced AR.

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.

Distinct characteristics of nasal polyps with and without eosinophilia

Introduction

Eosinophilic and noneosinophilic Nasal polyps (NPs) are different subtypes of NPs and require different treatment methods.

Objective

To compare the histologic characteristics, mRNA and protein expression between Nasal Polyps with and without eosinophilia.

Methods

NPs tissues were obtained from eighty-six NPs patients during surgery. Eosinophilic and noneosinophilic NPs were distinguished according to immunochemical results of the specimen. The histological, mRNA and protein expression features were compared between the two groups.

Results

In eosinophilic NPs, we observed a significantly higher GATA-3, IL-5, IL-4, IL-13 mRNA and protein expression. In noneosinophilic NPs, IL-17, IL-23 and RORc mRNA and protein expression were increased. Immunohistochemistry tests showed, more mast cells and less neutrophils in eosinophilic NPs compared with noneosinophilic NPs. Eosinophilic NPs patient presented more severe symptom scores when compared to noneosinophilic NPs.

Conclusion

We demonstrate for the first time that Th2 is the predominant reaction in eosinophilic NPs while Th17 is the predominant reaction in noneosinophilic NPs. Our study may provide new treatment strategy for NPs.

Airway responses towards allergens - from the airway epithelium to T cells

The prevalence of allergic diseases such as allergic rhinitis is increasing, affecting up to 30% of the human population worldwide. Allergic sensitization arises from complex interactions between environmental exposures and genetic susceptibility, resulting in inflammatory T helper 2 (Th2) cell-derived immune responses towards environmental allergens. Emerging evidence now suggests that an epithelial dysfunction, coupled with inherent properties of environmental allergens, can be responsible for the inflammatory responses towards allergens. Several epithelial-derived cytokines, such as thymic stromal lymphopoietin (TSLP), IL-25 and IL-33, influence tissue-resident dendritic cells (DCs) as well as Th2 effector cells. Exposure to environmental allergens does not elicit Th2 inflammatory responses or any clinical symptoms in nonatopic individuals, and recent findings suggest that a nondamaged, healthy epithelium lowers the DCs' ability to induce inflammatory T-cell responses towards allergens. The purpose of this review was to summarize the current knowledge on which signals from the airway epithelium, from first contact with inhaled allergens all the way to the ensuing Th2-cell responses, influence the pathology of allergic diseases.

The influence of house dust mite sublingual immunotherapy on the TSLP-OX40L signaling pathway in patients with allergic rhinitis

BACKGROUND

This study aimed to investigate the clinical efficacy of sublingual immunotherapy (SLIT) with house dust mite (HDM) extract and to examine T helper 2 (Th2)-type immune responses mediated by the thymic stromal lymphopoietin (TSLP-OX40L) signaling pathway in patients with moderate to severe allergic rhinitis (AR) after 12-month HDM SLIT.

METHODS

Forty-six cases of HDM-sensitized patients with persistent AR in southern China were enrolled in this study. Clinical efficacy of SLIT was assessed by determining the individual nasal symptom score (INSS) and total nasal symptom score (TNSS) after 12-month HDM SLIT. Moreover, the TSLP-OX40L signaling pathway was investigated through measurements of TSLP by enzyme-labeled immunosorbent assay (ELISA) and OX40L by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and flow cytometry.

RESULTS

After 12 months of HDM SLIT, TNSS and INSS were significantly decreased overall compared with baseline values (p < 0.001). By the end of the 12-month HDM SLIT, TNSS had declined by ∼50% compared with baseline, and the corresponding level of TSLP in nasal lavage decreased significantly (p < 0.05). The level of OX40L messenger RNA (mRNA) in blood was markedly decreased significantly after 12-month HDM SLIT compared with baseline (t = 12.300, p < 0.05). Furthermore, significant decreases in OX40L expression on the surface of peripheral blood mononuclear cells (PBMCs) (t = 13.100, p < 0.05) and OX40L expression on the surface of CD11c+CD86+ cells in PBMCs (t = 9.946, p < 0.05) after 12-month HDM SLIT were observed.

CONCLUSION

HDM SLIT downregulated Th2-type immune responses mediated by the TSLP-OX40L signaling pathway in patients with persistent moderate to severe AR.

Aspergillus fumigatus promotes T helper type 2 responses through thymic stromal lymphopoietin production by human corneal epithelial cells

BACKGROUND

Fungal keratitis is a major cause of blindness. To understand the mechanism of both innate and adaptive immunity in corneal infection is of great significance in the treatment and prevention of fungal keratitis. Our previous study concerned innate immunity. Here, we explored the potential role of thymic stromal lymphopoietin (TSLP) in adaptive immunity of fungal keratitis.

METHODS

Human corneal epithelial cells (HCECs) were stimulated with Aspergillus fumigatus hyphae (10(6) pieces per millilitre) with or without TSLP siRNA, and peripheral blood mononuclear cells (PBMCs) were cultured with or without TSLP. HCECs and PBMCs were co-cultured in a transwell system for various periods. Then we collected PBMCs and detected the proliferation and activation as well as T helper type 2 (Th2) differentiation by flow cytometry and quantitative real-time reverse transcription polymerase chain reaction. IgG and IgA levels in supernatants of PBMCs were measured by means of ELISA.

RESULTS

Thymic stromal lymphopoietin could induce a Th2 response in vitro, and the expression of TSLP was highly increased in HCECs stimulated with A. fumigatus hyphae. A. fumigatus-infected HCECs were capable of promoting human lymphocyte proliferation and activating human CD4(+) T cells, CD8(+) T cells and B cells by up-regulating the expression of activation marker CD69. Importantly, Th2 differentiation of CD4(+) T cells was induced during co-culture with A. fumigatus-infected HCECs in a transwell system. Interestingly, blockade of TSLP using siRNA prevented the proliferation and activation of lymphocytes as well as Th2 differentiation. We also detected an increased IgG level that was associated with TSLP.

CONCLUSION

These findings suggested that HCEC-derived TSLP has a key role in adaptive immune responses of fungal keratitis via skewing Th2 differentiation and promoting humoral immunity.

Protective effects of rutin through regulation of vascular endothelial growth factor in allergic rhinitis

BACKGROUND

Allergic rhinitis (AR) is an allergic inflammatory disease induced by various mediators released by infiltrating inflammatory cells. Vascular endothelial growth factor (VEGF) increases the airway inflammatory response by promoting vascular permeability. Furthermore, it is known that Allium hookeri and one of its constituent compounds, rutin (RU), have anti-inflammatory, antioxidant, and antiplatelet effects.

OBJECTIVE

The aim of this study was to evaluate the regulation of AR by RU and A. hookeri.

METHODS

We assessed the therapeutic effects and the regulatory mechanisms of A. hookeri and RU on phorbol 12-myristate 13-acetate plus A23187 (PMACI) stimulated human mast cell line (HMC) 1 cells, and ovalbumin (OVA) sensitized mouse model of AR.

RESULTS

A. hookeri and RU significantly inhibited the production and messenger RNA (mRNA) expression of VEGF in PMACI-stimulated HMC-1 cells and significantly decreased VEGF levels in our murine AR model. The increased rubs scores and immunoglobulin E and interleukin (IL) 4 levels in OVA-sensitized mice were significantly reduced by the administration of A. hookeri, and RU significantly inhibited the production and mRNA expression and RU. Also, A. hookeri and RU significantly reduced IL-4 and IL-5 production in OVA-stimulated splenocytes. Furthermore, A. hookeri and RU significantly decreased chemokine levels (intercellular adhesion molecule-1, macrophage inflammatory protein-2) in nasal mucosa tissues. In the mouse AR model, A. hookeri and RU significantly prevented eosinophil and mast cell infiltration and reduced inflammatory cytokine levels induced by OVA sensitization. In addition, A. hookeri and RU significantly reduced mast cell-derived caspase-1 activity in OVA-sensitized mice.

CONCLUSION

The present study showed that A. hookeri or RU had an anti-allergic inflammatory effects. Analysis of these results indicated that A. hookeri and RU might protect against AR.

Therapeutic Effect of Histone Deacetylase Inhibitor, Sodium Butyrate, on Allergic Rhinitis In Vivo

Despite the well-documented therapeutic effects of histone deacetylase inhibitor (HDACi) on various diseases, including arthritis and asthma, the therapeutic effect of HDACi on allergic rhinitis remains unmentioned in the literature. This study investigated the therapeutic effect of sodium butyrate (SoB), a form of HDACi, on mice with allergic rhinitis. The results showed that the expression levels of histone deacetylase 1 (HDAC1), histone deacetylase 3 (HDAC3), and thymic stromal lymphopoietin (TSLP) were significantly upregulated in mice with allergic rhinitis, whereas H3 acetylation at lysine 9 (H3AcK9) was decreased. The intranasal application of SoB inhibited the expression levels of TSLP levels and upregulated the expression of H3AcK9 in a mouse model of allergic rhinitis. Furthermore, SoB treatment significantly decreased the increased levels of ovalbumin-specific IgE and improved clinical symptoms and nasal mucosa epithelial morphology in the mouse model of allergic rhinitis. In addition, we further demonstrated that SoB treatment significantly increased the serum levels of IL-2 and IFN-γ and decreased the serum levels of IL-4 and IL-10, correcting the Th1/Th2 imbalance in the mouse model of allergic rhinitis. Taken together, our study suggests that SoB has the potential to treat allergic rhinitis.

Protective effect of TSLP delivered at the gut mucosa level by recombinant lactic acid bacteria in DSS-induced colitis mouse model

BACKGROUND

Thymic stromal lymphopoietin (TSLP) is a cytokine known to mature dendritics cells, lower pro-inflammatory IL-12 secretion, induce differentiation of anti-inflammatory FoxP3+ regulatory T cells (Treg). Moreover, Crohn's disease patients have shown a reduction of intestinal TSLP expression. To understand the role of TSLP in inflammation, we constructed Lactococcus lactis strain producing TSLP (LL-TSLP) and investigated the effect of its administration on dextran sulfate sodium (DSS)-induced colitis model in mice.

RESULTS

LL-TSLP secrete an active molecule which lowers secretion of IL-12 by dendritic cells. Treatment with LL-TSLP, increases the amount of TGF-β secreted by T cells in Mesenteric Lymph Node in healthy mice. In acute DSS-induced colitis, LL-TSLP delayed the Disease Activity Index and lowered histological score and colonic INF-γ production. In a DSS-recovery model, LL-TSLP induced a better protective effect if the strain was administered at the beginning of the colitis. At Day 4 of colitis we observed an induction of Treg by LL-TSLP.

CONCLUSIONS

TSLP showed an anti-inflammatory protective role in DSS-induced colitis. We have demonstrated that a short and early administration of LL-TSLP is more efficient than a long lasting treatment.

Murine allergic rhinitis and nasal Th2 activation are mediated via TSLP- and IL-33-signaling pathways

Thymic stromal lymphopoietin (TSLP) and IL-33 are epithelium-derived proallergic cytokines that contribute to allergic diseases. Although the involvement of TSLP in allergic rhinitis (AR) is suggested, the exact role of TSLP in AR is poorly understood. Furthermore, the relative contribution of TSLP and IL-33 in nasal allergic responses has not been described. In this study, we examined the roles of TSLP and IL-33 in AR by analyzing acute and chronic AR models. Acute AR mice were intraperitoneally immunized with ragweed, then intranasally challenged with ragweed pollen for four consecutive days. Chronic AR mice were nasally administrated ragweed pollen on consecutive days for 3 weeks. In both models, TSLP receptor (TSLPR)-deficient mice showed defective sneezing responses and reduced serum ragweed-specific IgE levels compared with wild-type (WT) mice. Analyses of bone-marrow chimeric mice demonstrated that hematopoietic cells were responsible for defective sneezing in TSLPR-deficient mice. In addition, FcεRI(+)-cell-specific TSLPR-deficient mice showed partial but significant reduction in sneezing responses. Of note, Th2 activation and nasal eosinophilia were comparable between WT and TSLPR-deficient mice. ST2- and IL-33-deficient mice showed defective Th2 activation and nasal eosinophilia to acute, but not chronic, ragweed exposure. TSLPR and ST2 double-deficient mice showed defective Th2 activation and nasal eosinophilia even after chronic ragweed exposure. These results demonstrate that TSLPR signaling is critical for the early phase response of AR by controlling the IgE-mast-cell/basophil pathway. The IL-33/ST2 pathway is central to nasal Th2 activation during acute allergen exposure, but both TSLPR and ST2 contribute to Th2 responses in chronically allergen-exposed mice.

Thymic stromal lymphopoietin (TSLP) secretion from human nasal epithelium is a function of TSLP genotype

Recent candidate gene and genome-wide association studies have identified "protective" associations between the single-nucleotide polymorphism (SNP) rs1837253 in the TSLP gene and risk for allergy, asthma, and airway hyperresponsiveness. The absence of linkage disequilibrium of rs1837253 with other SNPs in the region suggests it is likely a causal polymorphism for these associations, having functional consequences. We hypothesized that rs1837253 genotype would influence TSLP secretion from mucosal surfaces. We therefore evaluated the secretion of TSLP protein from primary nasal epithelial cells (NECs) of atopic and nonatopic individuals and its association with rs1837253 genotype. We found that although atopic sensitization does not affect the secretion of TSLP from NECs, there was decreased TSLP secretion in NECs obtained from heterozygous (CT; 1.8-fold) and homozygous minor allele (TT; 2.5-fold) individuals, as compared with NECs from homozygous major allele individuals (CC; P<0.05), after double-stranded RNA (dsRNA) stimulation (50 μg ml(-1)). Our novel results show that rs1837253 polymorphism may be directly involved in the regulation of TSLP secretion. This may help explain the protective association of this genetic variant with asthma and related traits. Identifying functional consequences of SNPs in genes with previously reported clinical associations is critical in understanding and targeting allergic inflammation.

Proallergic cytokines and group 2 innate lymphoid cells in allergic nasal diseases

Recent advances in our understanding of proallergic cytokines and group 2 innate lymphoid cells (ILC2s) indicate their critical roles in type 2 immunity-mediated disorders. Proallergic cytokines, interleukin (IL)-25, IL-33, and thymic stromal lymphopoietin, are released from epithelial cells in inflamed tissues and drive type 2 inflammation by acting on innate and acquired immune systems. ILC2s are an innate immune population that responds to proallergic cytokines by producing type 2 cytokines. In line with allergic disorders in the lung, skin, and intestine, emerging evidence suggests the involvement of proallergic cytokines and ILC2s in allergic nasal diseases such as chronic rhinosinusitis with polyps (CRSwNP), allergic fungal rhinosinusitis, and allergic rhinitis (AR). In CRSwNP patients, both proallergic cytokine levels and ILC2s frequency are increased in the nasal mucosa. Increased proallergic cytokine levels correlate with poorer disease outcomes in CRSwNP. Levels of nasal proallergic cytokines are also elevated in AR patients. In addition, animal studies demonstrate that cytokines are essential for the development of AR. It is becoming clear that the proallergic cytokine/ILC2s axis participates in allergic diseases by multiple mechanisms dependent upon the inflammatory context. Thus, a thorough understanding of these cytokines and ILC2s including their tissue- and disease-specific roles is essential for targeting the pathways to achieve therapeutic applications.

The importance of TSLP in allergic disease and its role as a potential therapeutic target

Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine similar to IL- 7, whose gene is located on chromosome 5q22.1 and it exerts its biological function through the TSLP-Receptor (TSLP-R). TSLP is expressed primarily by epithelial cells at barrier surfaces such as the skin, gut and lung in response to danger signals. Since it was cloned in 1994, there has been accumulating evidence that TSLP is crucial for the maturation of antigen presenting cells and hematopoietic cells. TSLP genetic variants and its dysregulated expression have been linked to atopic diseases such as atopic dermatitis, asthma, allergic rhinitis and eosinophilic esophagitis.

IL-33 and Thymic Stromal Lymphopoietin in mast cell functions

Thymic Stromal Lymphopoietin (TSLP) and Interleukin 33 (IL-33) are two cytokines released by cells that are in proximity to our environment, e.g., keratinocytes of the skin and epithelial cells of the airways. Pathogens, allergens, chemicals and other agents induce the release of TSLP and IL-33, which are recognized by mast cells. TSLP and IL-33 affect several mast cell functions, including growth, survival and mediator release. These molecules do not directly induce exocytosis, but cause release of de novo synthesized lipid mediators and cytokines. TSLP and IL-33 are also implicated in inflammatory diseases where mast cells are known to be an important part of the pathogenesis, e.g., asthma and atopic dermatitis. In this chapter we describe and discuss the implications of TSLP and IL-33 on mast cell functions in health and disease.

Inhibition of IL-32 signaling by bamboo salt decreases pro-inflammatory responses in cellular models of allergic rhinitis

Previously, we showed the antiallergic effect of bamboo salt (BS) in allergic rhinitis (AR). We also demonstrated that interleukin (IL)-32 is an important mediator of AR. The aim of this study was to evaluate the effect and specific underlying mechanism of BS, NaCl, and the mineral mixture (components of BS other than NaCl, including zinc, magnesium, and potassium, Mix) on IL-32 signaling using the human monocyte cell line, THP-1. Here, we documented for the first time that BS significantly decreased IL-32-induced thymic stromal lymphopoietin protein and mRNA expression in THP-1 cells. BS treatment significantly inhibited IL-32-induced proinflammatory cytokine production including IL-1β, IL-8, and tumor necrosis factor (TNF)-α by suppressing nuclear factor-κB, p38 mitogen-activated kinase, and caspase-1 pathways. The presence of BS or Mix effectively suppressed IL-32-induced macrophage-like cell differentiation but NaCl exhibited no effect on monocyte-to-macrophage-like cell differentiation. In IL-32-induced macrophages, the production of IL-1β, IL-6, IL-8, and TNF-α, and expression of inducible nitric oxide synthase and cyclooxygenase-2, induced by lipopolysaccharide was dramatically decreased in a dose-dependent manner after BS treatment. BS also significantly decreased IL-32-induced nitric oxide, IL-8, and TNF-α production. Furthermore, BS inhibited granulocyte-macrophage colony-stimulating factor-induced IL-32 and IL-8 protein and mRNA expression in EOL-1 cells. Taken together, BS suppressed inflammatory activity by inhibiting the IL-32 signaling pathway in AR.

Cytokine profiles in allergic rhinitis

Allergic rhinitis, particularly seasonal allergic rhinitis, is considered a classic Th2-mediated disease, with important contributions to pathology by interleukins 4, 5 and 13. As such, allergic rhinitis is an excellent model for studying allergic inflammation, with findings potentially relevant to the mechanism of lower airways inflammation seen in allergic asthma. However, recent evidence has revealed roles for additional non-Th2 cytokines in asthma, including IL-17 family cytokines and epithelial-derived cytokines. Additionally, putative roles for epithelial-derived cytokines and innate lymphoid cells have been described in chronic rhinosinusitis with nasal polyps. Here, evidence for the involvement of different cytokines and cytokine groups in allergic rhinitis is considered.

Thymic stromal lymphopoietin and the pathophysiology of atopic disease

Thymic stromal lymphopoietin (TSLP) is an IL-7-related cytokine expressed predominantly by barrier epithelial cells. TSLP is a potent activator of several cell types, including myeloid-derived dendritic cells, monocytes/macrophages and mast cells. Recent studies have revealed an important role for TSLP in the initiation and progression of allergic inflammatory diseases. In this review, we will discuss the role of TSLP in atopic diseases, as well as its function in immune homeostasis.

The biology of thymic stromal lymphopoietin (TSLP)

Originally shown to promote the growth and activation of B cells, thymic stromal lymphopoietin (TSLP) is now known to have wide-ranging impacts on both hematopoietic and nonhematopoietic cell lineages, including dendritic cells, basophils, eosinophils, mast cells, CD4⁺, CD8⁺ and natural killer T cells, B cells and epithelial cells. While TSLP's role in the promotion of TH2 responses has been extensively studied in the context of lung- and skin-specific allergic disorders, it is becoming increasingly clear that TSLP may impact multiple disease states within multiple organ systems, including the blockade of TH1/TH17 responses and the promotion of cancer and autoimmunity. This chapter will highlight recent advances in the understanding of TSLP signal transduction, as well as the role of TSLP in allergy, autoimmunity and cancer. Importantly, these insights into TSLP's multifaceted roles could potentially allow for novel therapeutic manipulations of these disorders.

Hop water extract inhibits double-stranded RNA-induced thymic stromal lymphopoietin release from human nasal epithelial cells

BACKGROUND

Thymic stromal lymphopoietin (TSLP) acts as a master switch for allergic inflammation and plays a key role in allergic diseases, including allergic rhinitis. Double-stranded RNA (dsRNA) recognized by Toll-like receptor 3 (TLR3) strongly activates TSLP release from human nasal epithelial cells (HNECs). Hop (Humulus lupulus L.) extracts have been shown to have potent pharmacologic effects on inflammation.

METHODS

To investigate whether a hop water extract (HWE) prevents TSLP release from HNECs, human telomerase reverse transcriptase (hTERT)-transfected HNECs, used as a model of normal HNECs, were pretreated with HWE before treatment with the TLR3 ligand Polyinosine-polycytidylic acid (poly[I:C]).

RESULTS

In the hTERT-transfected HNECs, treatment with HWE significantly reduced poly(I:C)-induced production and release of TSLP in a dose-dependent manner, as well as dexamethasone. Treatment with the protein kinase C (PKC) inhibitor GF109203X and NF-κB inhibitor IMD-0354 also reduced poly(I:C)-induced TSLP release from hTERT-transfected HNECs. Treatment with HWE efficiently prevented up-regulation of PKC activity by 12-O-tetradecanoyl phorbol-13-acetate but not NF-κB activity induced by IL-1β in hTERT-transfected HNECs.

CONCLUSION

Our results clearly indicated that HWE inhibited dsRNA-induced production and release of TSLP via a PKC signal pathway in HNECs and it may have potent preventive effects against allergic rhinitis.

Functional heterogeneity in the basophil cell lineage

CD4(+) T-helper type 2 (Th2) cells, characterized by their expression of interleukin (IL)-4, IL-5, IL-9, and IL-13, are required for immunity to helminth parasites and promote the pathological inflammation associated with asthma and allergic diseases. Recent reports from a number of laboratories have indicated that basophils can influence the induction and/or effector stages of Th2 cytokine-mediated inflammation. However, the impact of basophils appears to depend on the anatomical location and nature of the infectious or inflammatory stimulus. This review highlights the factors that regulate basophil development and activation and describes known basophil effector functions. Further, we discuss the recent identification of phenotypic and functional heterogeneity within murine and human basophil populations and discuss how these findings may explain the context-dependent influence of basophils on either the propagation, regulation, or effector phases of Th2 cytokine-associated inflammation.