Allergic rhinitis (AR) affects up to 80% of children with asthma and increases asthma severity. Thymic stromal lymphopoietin (TSLP) is a key mediator of allergic inflammation. The role of the TSLP gene (TSLP) in the pathogenesis of AR has not been studied.
To test for associations between variants in TSLP, TSLP-related genes, and AR in children with asthma.
We genotyped 15 single nucleotide polymorphisms (SNPs) in TSLP, OX40L, IL7R, and RXRα in three independent cohorts: 592 asthmatic Costa Rican children and their parents, 422 nuclear families of North American children with asthma, and 239 Swedish children with asthma. We tested for associations between these SNPs and AR. As we previously reported sex-specific effects for TSLP, we performed overall and sex-stratified analyses. We additionally performed secondary analyses for gene-by-gene interactions.
Across the three cohorts, the T allele of TSLP SNP rs1837253 was undertransmitted in boys with AR and asthma as compared to boys with asthma alone. The SNP was associated with reduced odds for AR (odds ratios ranging from 0.56 to 0.63, with corresponding Fisher's combined P value of 1.2 × 10-4). Our findings were significant after accounting for multiple comparisons. SNPs in OX40L, IL7R, and RXRα were not consistently associated with AR in children with asthma. There were nominally significant interactions between gene pairs.
TSLP SNP rs1837253 is associated with reduced odds for AR in boys with asthma. Our findings support a role for TSLP in the pathogenesis of AR in children with asthma.
The genetic etiology of eosinophilic esophagitis (EE) has been largely unexplored until a recent genome-wide association study identified a disease susceptibility locus on 5q22, a region that harbors the thymic stromal lymphopoietin (TSLP) gene. However, it is unclear whether the observed genetic associations with EE are disease-specific or confounded by the high rate of allergy in EE patients. In addition, the genetic contributions of other allergy associated genes to EE risk have not been explored.
We aimed to delineate single nucleotide polymorphisms (SNP)s that associated with EE apart from allergy.
We utilized a custom array containing 738 SNPs in 53 genes implicated in allergic and/or immune responses to genotype 220 allergic or 246 non-allergic controls and a discovery cohort of 170 EE patients. We replicated a statistically significant SNP association in an independent case-control cohort and examined the induction of the candidate gene in primary esophageal epithelial cells.
A single SNP residing in the TSLP gene reached Bonferroni LD adjusted significance and only when EE cases were compared with allergic controls (rs10062929, P = 4.11 × 10−5, odds ratio = 0.35). A non-synonymous polymorphism in the TSLP receptor on Xp22.3 and Yp11.3 was significantly associated with disease only in male EE patients. Primary esophageal epithelial cells expressed TSLP mRNA following Toll-like receptor 3 (TLR3) stimulation.
These data collectively identify TSLP as a candidate gene critically involved in EE susceptibility beyond its role in promoting Th2 responses.
Eosinophilic esophagitis; thymic stromal lymphopoietin; single nucleotide polymorphism; allergy; cytokine receptor-like factor 2; Toll-like receptor 3
Thymic stromal lymphopoietin (TSLP) triggers dendritic cell–mediated T helper (Th) 2 inflammatory responses. A single-nucleotide polymorphism (SNP), rs3806933, in the promoter region of the TSLP gene creates a binding site for the transcription factor activating protein (AP)–1. The variant enhances AP-1 binding to the regulatory element, and increases the promoter–reporter activity of TSLP in response to polyinosinic-polycytidylic acid (poly[I:C]) stimulation in normal human bronchial epithelium (NHBE). We investigated whether polymorphisms including the SNP rs3806933 could affect the susceptibility to and clinical phenotypes of bronchial asthma. We selected three representative (i.e., Tag) SNPs and conducted association studies of the TSLP gene, using two independent populations (639 patients with childhood atopic asthma and 838 control subjects, and 641 patients with adult asthma and 376 control subjects, respectively). We further examined the effects of corticosteroids and a long-acting β2-agonist (salmeterol) on the expression levels of the TSLP gene in response to poly(I:C) in NHBE. We found that the promoter polymorphisms rs3806933 and rs2289276 were significantly associated with disease susceptibility in both childhood atopic and adult asthma. The functional SNP rs3806933 was associated with asthma (meta-analysis, P = 0.000056; odds ratio, 1.29; 95% confidence interval, 1.14–1.47). A genotype of rs2289278 was correlated with pulmonary function. Moreover, the induction of TSLP mRNA and protein expression induced by poly(I:C) in NHBE was synergistically impaired by a corticosteroid and salmeterol. TSLP variants are significantly associated with bronchial asthma and pulmonary function. Thus, TSLP may serve as a therapeutic target molecule for combination therapy.
asthma; TSLP; bronchial epithelial cells; combination therapy; genetic polymorphisms
Rationale: The basis for gender influences on allergen-specific IgEs is unclear.
Objectives: To perform regular and sex-stratified genomewide linkage analyses of IgE to each of three allergens (Ascaris lumbricoides, Blatella germanica [German cockroach]), and Dermatophagoides pteronyssinus [dust mite]) and to conduct an association study of a candidate gene in a linked genomic region.
Methods: Genomewide linkage analyses of allergen-specific IgEs were conducted in 653 members of eight large families of Costa Rican children with asthma. An analysis of the association between single-nucleotide polymorphisms in thymic stromal lymphopoietin (TSLP) and IgE measurements was conducted in 417 parent–child trios in Costa Rica. Significant results were replicated in 470 families of white children in the Childhood Asthma Management Program (CAMP).
Measurements and Main Results: Among all subjects, there was suggestive evidence of linkage (LOD ⩾ 2.72) to IgE to Ascaris (on chromosome 7q) and IgE to dust mite (on chromosomes 7p and 12q). In a sex-stratified analysis, there was significant evidence of linkage to IgE to cockroach on chromosome 5q23 (peak LOD, 4.14 at 127 cM) in female subjects. TSLP is located within the 1.5 LOD-unit support interval for this linkage peak and has female-specific effects on lung disease in mice. In a sex-stratified analysis, the T allele of single-nucleotide polymorphism rs2289276 in TSLP was associated with reductions in IgE to cockroach (in Costa Rican girls) and total IgE (in girls in Costa Rica and in CAMP; P value for sex-by-genotype interaction, <0.01 in both studies).
Conclusions: Consistent with findings in murine models, a variant in TSLP may have female-specific effects on allergic phenotypes.
immunoglobulin E; linkage; thymic stromal lymphopoietin; single-nucleotide polymorphisms
Graves disease (GD) is an organ-specific autoimmune disease characterized by hyperthyroidism, diffuse goiter, autoantibodies against thyroid-specific antigens, and dermopathy. Studies of GD have demonstrated the importance of the Th2 and Th17 immune responses in mediating disease progression. In the present study, we investigated the role of a Th2 cytokine, thymic stromal lymphopoietin (TSLP), in GD and Th17 differentiation.
In this study, we genotyped 470 patients with GD at 3 single nucleotide polymorphisms (SNPs) in TSLP. In addition, the serum concentrations of TSLP were determined in 432 patients and 272 controls. Ten patients and controls each were further screened using in vitro Th17 differentiation assays. The SNPs were genotyped using ABI TaqMan® SNP genotyping assays. For the Th17 differentiation assays, peripheral blood mononuclear cells (PBMCs) isolated from the patients and controls were placed into Th17 differentiation media, and interleukin 17 expression levels were determined.
Haplotype analysis indicated that patients with the Ht3 (TCC) haplotype have a 3.28-fold higher risk of developing GD (p = 0.007), whereas those with the Ht5 (TCG) haplotype had a 0.03-fold, reduced risk of developing GD (p = 1 × 10−14). SNP rs3806933 (p = 0.007) was associated with female Graves ophthalmopathy (GO). TSLP expression levels were higher in GD patients than in control subjects, and TLSP was also shown to promote the differentiation of Th17 cells in GD patients.
These results suggest that polymorphisms in TSLP may be used as genetic markers for the diagnosis and prognosis of GD. Furthermore, TLSP may be a target for treating GD.
Graves’ disease; Graves’ ophthalmopathy; Thymic stromal lymphopoietin; Th17
CD4+ T helper type 2 (Th2) cells characterized by their expression of IL-4, IL-5, IL-9 and IL-13 are required for immunity to helminth parasites1 and promote the pathological inflammation associated with asthma and allergic diseases2. Polymorphisms in the gene encoding the cytokine thymic stromal lymphopoietin (TSLP) are associated with the development of multiple allergic disorders in humans, suggesting that TSLP is a critical regulator of allergic diseases3-6. Supporting genetic analyses, exaggerated TSLP production is associated with asthma, atopic dermatitis and food allergies in patients, and studies in murine systems demonstrated that TSLP promotes Th2 cytokine-mediated immunity and inflammation5, 7-12. However, the mechanisms through which TSLP promotes Th2 cytokine responses remain poorly defined. Here we demonstrate that TSLP promotes systemic basophilia, that disruption of TSLP-TSLPR interactions results in defective basophil responses and that TSLPR-sufficient basophils can restore Th2 cell-dependent immunity in vivo. TSLP acted directly on bone marrow- resident progenitors to selectively promote basophil responses. Critically, TSLP could elicit basophil responses in both IL-3-sufficient and IL-3-deficient environments and genome-wide transcriptional profiling and functional analyses identified heterogeneity between TSLP-elicited versus IL-3-elicited basophils. Further, activated human basophils expressed the TSLPR and basophils isolated from eosinophilic esophagitis (EoE) patients were heterogeneous. Collectively, these studies identify previously unrecognized heterogeneity within the basophil cell lineage and indicate that expression of TSLP may influence susceptibility to multiple allergic diseases by regulating basophil hematopoiesis and eliciting a population of functionally distinct basophils that promote Th2 cytokine-mediated inflammation.
TSLP; Th2 cytokine responses; innate immunity; basophils; hematopoiesis
Single nucleotide polymorphisms (SNPs) in thymic stromal lymphopoietin (TSLP) have been associated with IgE (in girls) and asthma (in general). We sought to determine whether TSLP SNPs are associated with asthma in a sex-specific fashion.
We conducted regular and sex-stratified analyses of association between SNPs in TSLP and asthma in families of asthmatic children in Costa Rica. Significant findings were replicated in white and African-American participants in the Childhood Asthma Management Program, in African Americans in the Genomic Research on Asthma in the African Diaspora study, in whites and Hispanics in the Children’s Health Study, and in whites in the Framingham Heart Study (FHS).
Two SNPs in TSLP (rs1837253 and rs2289276) were significantly associated with a reduced risk of asthma in combined analyses of all cohorts (p values of 2×10−5 and 1×10−5, respectively). In a sex-stratified analysis, the T allele of rs1837253 was significantly associated with a reduced risk of asthma in males only (p= 3×10−6). Alternately, the T allele of rs2289276 was significantly associated with a reduced risk of asthma in females only (p= 2×10−4). Findings for rs2289276 were consistent in all cohorts except the FHS.
TSLP variants are associated with asthma in a sex-specific fashion.
asthma; genetic association; sex-specific; thymic stromal lymphopoietin; TSLP
Thymic stromal lymphopoietin (TSLP), an IL7-like cytokine produced by bronchial epithelial cells is upregulated in asthma and induces dendritic cell maturation supporting a Th2 response. Environmental pollutants, including tobacco smoke and diesel exhaust particles upregulate TSLP suggesting that TSLP may be an interface between environmental pollution and immune responses in asthma. Since asthma is prevalent in urban communities, variants in the TSLP gene may be important in asthma susceptibility in these populations.
To determine whether genetic variants in TSLP are associated with asthma in an urban admixed population.
Methodology and Main Results
Ten tag-SNPs in the TSLP gene were analyzed for association with asthma using 387 clinically diagnosed asthmatic cases and 212 healthy controls from an urban admixed population. One SNP (rs1898671) showed nominally significant association with asthma (odds ratio (OR) = 1.50; 95% confidence interval (95% CI): 1.09–2.05, p = 0.01) after adjusting for age, BMI, income, education and population stratification. Association results were consistent using two different approaches to adjust for population stratification. When stratified by smoking status, the same SNP showed a significantly increased risk associated with asthma in ex-smokers (OR = 2.00, 95% CI: 1.04–3.83, p = 0.04) but not significant in never-smokers (OR = 1.34; 95% CI: 0.93–1.94, p = 0.11). Haplotype-specific score test indicated that an elevated risk for asthma was associated with a specific haplotype of TSLP involving SNP rs1898671 (OR = 1.58, 95% CI: 1.10–2.27, p = 0.01). Association of this SNP with asthma was confirmed in an independent large population-based cohort consortium study (OR = 1.15, 95% CI: 1.07–1.23, p = 0.0003) and the results stratified by smoking status were also validated (ex-smokers: OR = 1.21, 95% CI: 1.08–1.34, p = 0.003; never-smokers: OR = 1.06, 95% CI: 0.94–1.17, p = 0.33).
Genetic variants in TSLP may contribute to asthma susceptibility in admixed urban populations with a gene and environment interaction.
Thymic stromal lymphopoietin (TSLP) has been recently implicated as a key molecule for initiating allergic inflammation at the epithelial cell-dendritic cell (DC) interface. In humans, aberrant TSLP expression is observed in allergic tissues, such as lesional skins of atopic dermatitis, lungs of asthmatics, nasal mucosa of atopic rhinitis and nasal polyps, and ocular surface of allergic keratoconjunctivitis. TSLP is produced predominantly by damaged epithelial cells and stimulates myeloid DCs (mDCs). TSLP-activated mDCs can promote the differentiation of naïve CD4+ T cells into a Th2 phenotype and the expansion of CD4+ Th2 memory cells in a unique manner dependent on OX40L, one of the tumor necrosis factor superfamily members with Th2-promoting function, and lack of production of IL-12. From a genetic point of view, multiple genome-wide association studies have repeatedly identified the TSLP gene as one of the loci associated with susceptibility to allergic diseases. Thus, TSLP is a rational therapeutic target for the treatment of allergic disorders. Elucidating the mechanisms that regulate TSLP expression and the effects of TSLP on orchestrating the immune response toward a Th2 phenotype is essential for developing anti-TSLP therapy.
allergic inflammation; dendritic cells (DCs); OX40L; Th2 cells; thymic stromal lymphopoietin (TSLP)
Eosinophilic esophagitis (EoE) is a food allergy-associated inflammatory disease characterized by esophageal eosinophilia. EoE has become increasingly common, but current management strategies are nonspecific. Thus, there is an urgent need to identify specific immunological pathways that could be targeted to treat this disease. EoE is associated with polymorphisms in the gene that encodes thymic stromal lymphopoietin (TSLP), a cytokine that promotes allergic inflammation, but how TSLP might contribute to EoE disease pathogenesis remains unknown. Here, we describe a new mouse model of EoE-like disease that developed independently of IgE but was dependent on TSLP-elicited basophils. Therapeutic TSLP neutralization or basophil depletion also ameliorated established EoE-like disease. Critically, in human subjects with EoE, we observed elevated TSLP levels and exaggerated basophil responses in esophageal biopsies, and a gain-of-function TSLP polymorphism was associated with increased basophil responses. Together, these data suggest that the TSLP-basophil axis could be therapeutically targeted to treat EoE.
Thymic stromal lymphopoietin (TSLP) has been implicated in the development of allergic inflammation by promoting Th2-type responses and has become a potential therapeutic target. Using in vitro T cell differentiation cultures we were able to validate that TSLP played a more critical role in the early development of Th2 immune responses with less significant enhancement of already developed Th2 responses. Adoptive transfer of naive DO11.10 ovalbumin-specific T cells followed by airway exposure to ovalbumin showed an early impairment of Th2 immune response in TSLP−/− mice compared to wild type mice during the development of a Th2 response. In contrast, transfer of already differentiated Th2 cells into TSLP−/− mice did not change lung pathology or Th2 cytokine production upon ovalbumin challenge compared to transfer into wild type mice. An allergen-induced Th2 airway model demonstrated that there was only a difference in gob5 expression (a mucus-associated gene) between wild type and TSLP−/− mice. Furthermore, when allergic animals with established disease were treated with a neutralizing anti-TSLP antibody there was no change in airway hyperreponsiveness (AHR) or Th2 cytokine production compared to the control antibody treated animals, whereas a change in gob5 gene expression was also observed similar to the TSLP−/− mouse studies. In contrast, when animals were treated with anti-TSLP during the initial stages of allergen sensitization there was a significant change in Th2 cytokines during the final allergen challenge. Collectively, these studies suggest that in mice TSLP has an important role during the early development of Th2 immune responses, whereas its role at later stages of allergic disease may not be as critical for maintaining the Th2-driven allergic disease.
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.
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.
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.
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.
Nasal polyps; Th2 cytokines; TSLP; eosinophils; IgE
Even though thymic stromal lymphopoietin (TSLP) has been implicated in the development of allergic inflammation, its influence on immune tolerance mediated by regulatory T cells (Treg) have not been explored. We aimed to dissect the influence of TSLP on immunosuppressive activities of Treg and its potential consequences in human allergic asthma.
In vitro culture system was utilized to study the effects of TSLP on human Treg. The functional competency of pulmonary Treg from a cohort of 15 allergic asthmatic, 15 healthy control, and 15 non-allergic asthmatic subjects was also evaluated by suppression assays and flow cytometric analysis.
Activated pulmonary Treg expressed TSLP-R and responded to TSLP-mediated activation of STAT5. TSLP directly and selectively impaired IL-10 production of Treg and inhibited their suppressive activity. In human allergic asthma, pulmonary Treg exhibited a significant decrease in suppressive activity and IL-10 production compared to healthy control and non-allergic asthmatic counterparts. These functional alterations were associated with elevated TSLP expression in bronchoaveolar lavage fluid (BAL) of allergic asthmatic subjects. Furthermore, allergic asthmatic BAL could suppress IL-10 production by healthy control pulmonary Treg in a TSLP-dependent manner.
These results provide the first evidences for a direct role of TSLP in the regulation of suppressive activities of Treg. TSLP mediated inhibition of Treg function might present a novel pathologic mechanism to dampen tolerogenic immune responses in inflamed asthmatic airway.
Atopic dermatitis (AD or eczema) often precedes the development of asthma and allergic rhinitis in atopic subjects, a phenomenon known as atopic march. An important role of epicutaneous (e.c.) sensitization has been recognized in the atopic march; however, the factors involved in e.c. sensitization remain poorly understood. Our previous studies using mouse models have shown that induced overexpression of Thymic Stromal Lymphopoietin (TSLP) in keratinocytes not only triggers an AD [Li, M. et al. Proc Natl Acad Sci U S A. 2006;103:11736–11741] but also aggravates experimental asthma induced by systemic sensitization and airway challenge of ovalbumin (OVA) [Zhang Z, et al. Proc Natl Acad Sci U S A. 2009;106:1536–1541], suggesting that TSLP represents an important factor linking AD to asthma. However, whether keratinocytic TSLP is essentially required for developing e.c. sensitization and triggering the atopic march remained to be determined.
We develop a mouse model in which e.c. sensitization of OVA through tape-stripped skin is followed by intranasal challenge to induce an allergic asthma. TSLPep−/−mice (in which TSLP is selectively ablated in epidermal keratinocytes at adult stage) or TSLPover mice (in which keratinocytic TSLP overexpression is induced by topical application of MC903, a low-calcemic vitamin D analog) are subjected to this mouse model.
Upon OVA e.c. treatment, TSLPep−/− mice develop a defective allergen sensitization evidenced by decreased production of OVA-specific IgE and IgG1 and a reduction of the secretion of Th2 and Th17 (but not Th1) cytokines by in vitro OVA stimulated splenocytes. TSLPep−/− mice also exhibit a decreased OVA-induced skin inflammation. Finally, upon intranasal challenge, TSLPep−/− mice develop a less severe airway allergic inflammation and a reduced airway hyperresponsiveness. In contrast, overproduction of keratinocytic TSLP boosts the e.c. sensitization and triggers an aggravated asthma.
Our results demonstrate an important role of keratinocytic TSLP in developing epicutaneous sensitization, generating allergic skin inflammation and triggering the atopic march. Thus, blocking the expression or activity of keratinocytic TSLP could be helpful to limit epicutaneous sensitization and prevent the atopic march.
Chronic rhinosinusitis with nasal polyps (CRSwNP) is associated with Th2-dominant inflammation. Thymic stromal lymphopoietin (TSLP) is a cytokine that triggers dendritic cell-mediated Th2 inflammatory responses and that enhances IL-1-dependent Th2 cytokine production in mast cells. Although elevated levels of TSLP mRNA have been found in nasal polyps (NPs), expression of TSLP protein and its function in CRS have not been fully explored.
The objective of this study was to investigate the role of TSLP in CRS.
We investigated the presence and stability of TSLP protein in NPs by ELISA and western blot, and the function of TSLP in nasal tissue extracts with a bioassay based upon activation of human mast cells.
Although TSLP mRNA was significantly increased in NP tissue from patients with CRSwNP compared to uncinate tissue from patients with CRS or control subjects, TSLP protein was significantly decreased in NP tissue as detected by the commercial ELISA kit. We found that recombinant TSLP was time-dependently degraded by NP extracts and this degradation was completely inhibited by a protease inhibitor cocktail, suggesting that TSLP is sensitive to tissue proteases. Interestingly, NP extract-treated TSLP had higher activity in mast cells, although the amount of full length TSLP was reduced up to 85%. NP extracts significantly enhanced IL-1β-dependent IL-5 production in mast cells compared with uncinate tissue homogenates, and responses were significantly inhibited by anti-TSLP, suggesting that NP contain biologically relevant levels of TSLP activity.
TSLP and its metabolic products may play an important role in the inflammation in CRSwNP.
Chronic rhinosinusitis; Nasal polyps; TSLP; Epithelial cells; Mast cells; Th2 cells; IL-5; Proteases
Thymic stromal lymphopoietin (TSLP) is a newly identified IL-7–like cytokine known to be expressed in airway biopsies of patients with asthma and chronic obstructive pulmonary disease. As both diseases may be induced or exacerbated by cigarette smoking, it is possible that TSLP represents an important link between cigarette smoke exposure and inflammatory signaling in the airways. In this regard, TSLP appears to also be expressed in airway smooth muscle (ASM); however, its role is unknown. In the current study, we examined TSLP and the TSLP receptor (TSLP-R) expression and function in human ASM cells under normal conditions and following exposure to cigarette smoke extract (CSE). Western blot analysis of human ASM cells showed significant expression of TSLP and TSLP-R, with increased expression of both by overnight exposure to 1 or 2% CSE. Furthermore, CSE increased TSLP release by ASM. In parallel experiments using enzymatically dissociated human ASM cells loaded with the Ca2+ indicator fura 2-AM and imaged using fluorescence microscopy, we evaluated the effects of CSE exposure on intracellular Ca2+ ([Ca2+]i) responses to agonist stimulation. [Ca2+]i responses to histamine were increased with overnight CSE exposure. Exposure to TSLP also resulted in elevated responses, which were blunted by TSLP and TSLP-R Abs. Importantly, the enhancing effects of CSE on [Ca2+]i responses were also blunted by these Abs. These effects were associated with CSE- and TSLP-induced changes in STAT5 phosphorylation. Overall, these novel data suggest that cigarette smoke, TSLP, and ASM are functionally linked and that cigarette smoke-induced increase in airway contractility may be mediated via ASM-derived increases in TSLP signaling.
Thymic stromal lymphopoietin (TSLP) is a cytokine with multiple effects on the body. For one thing, TSLP induces Th2 immunoreaction and facilitates allergic reaction; for another, it promotes the differentiation of naturally occurring CD4+CD25+Foxp3+ regulatory T cells (nTregs) and maintains immune tolerance. However, the exact role of TSLP in atherosclerosis remains unknown.
Methods and Results
In vitro, we examined the phenotype of TSLP‐conditioned bone marrow dendritic cells (TSLP‐DCs) of apolipoprotein E–deficient (ApoE−/−) mice and their capacity to induce the differentiation of Tregs. Our results indicated that TSLP‐DCs obtained the characteristics of tolerogenic dendritic cells and increased a generation of CD4+ latency‐associated peptide (LAP)+ Tregs and nTregs when cocultured with naive T cells. In addition, the functional relevance of TSLP and TSLP‐DCs in the development of atherosclerosis was also determined. Interestingly, we found that TSLP was almost absent in cardiovascular tissue of ApoE−/− mice, and TSLP administration increased the levels of antioxidized low‐density lipoprotein IgM and IgG1, but decreased the levels of IgG2a in plasma. Furthermore, mice treated with TSLP and TSLP‐DCs developed significantly fewer (32.6% and 28.2%, respectively) atherosclerotic plaques in the aortic root compared with controls, along with increased numbers of CD4+LAP+ Tregs and nTregs in the spleen and decreased inflammation in the aorta, which could be abrogated by anti‐TGF‐β antibody.
Our results revealed a protective role for TSLP in atherosclerosis that is possibly mediated by reestablishing a tolerogenic immune response, which may represent a novel possibility for treatment or prevention of atherosclerosis.
atherosclerosis; CD4+LAP+ Tregs; TGF‐β; tolerogenic dendritic cells; TSLP
Thymic stromal lymphopoietin (TSLP) is an epithelial cell derived cytokine important for the initiation and development of T helper (Th2) cell-mediated allergic inflammation. In this study, we identified a positive association between interleukin-9 (IL-9) and TSLP concentration in the serum of infants with atopic dermatitis. In primary cell cultures, the addition of TSLP led to an increase in IL-9 production from human and mouse Th9 cells, and induced an increase in Signal Transducer and Activator of Transcription 5 (STAT5) activation and binding to the Il9 promoter. In vivo, use of an adoptive transfer model demonstrated that TSLP promoted IL-9-dependent, Th9 cell-induced allergic inflammation by acting directly on T cells. Moreover, transgenic expression of TSLP in the lung stimulated IL-9 production in vivo, and anti-IL-9 treatment attenuated TSLP-induced airway inflammation. Together, our results demonstrate that TSLP promotes Th9 cell differentiation and function, and define a requirement for IL-9 in TSLP-induced allergic inflammation.
Few studies have investigated the significance of decreased FEV1 in non-COPD, nonasthmatic healthy subjects. We hypothesized that a lower FEV1 in these subjects is a potential marker of an increased susceptibility to obstructive lung disease such as asthma and COPD. This was a cross-sectional analysis of 1505 Japanese adults. We divided the population of healthy adults with no respiratory diseases whose FEV1/FVC ratio was ≥70% (n = 1369) into 2 groups according to their prebronchodilator FEV1 (% predicted) measurements: <80% (n = 217) and ≥80% (n = 1152). We compared clinical data – including gender, age, smoking habits, total IgE levels, and annual decline of FEV1 – between these 2 groups. In addition, as our group recently found that TSLP variants are associated with asthma and reduced lung function, we assessed whether TSLP single nucleotide polymorphisms (SNPs) were associated with baseline lung function in non-COPD, nonasthmatic healthy subjects (n = 1368). Although about half of the subjects with lower FEV1 had never smoked, smoking was the main risk factor for the decreased FEV1 in non-COPD, nonasthmatic subjects. However, the subjects with lower FEV1 had a significantly higher annual decline in FEV1 independent of smoking status. Airflow obstruction was associated with increased levels of total serum IgE (P = 0.029) and with 2 functional TSLP SNPs (corrected P = 0.027–0.058 for FEV1% predicted, corrected P = 0.015–0.033 for FEV1/FVC). This study highlights the importance of early recognition of a decreased FEV1 in healthy subjects without evident pulmonary diseases because it predicts a rapid decline in FEV1 irrespective of smoking status. Our series of studies identified TSLP variants as a potential susceptibility locus to asthma and to lower lung function in non-COPD, nonasthmatic healthy subjects, which may support the contention that genetic determinants of lung function influence susceptibility to asthma.
airflow obstruction; asthma; chronic obstructive pulmonary disease; pulmonary function test; thymic stromal lymphopoietin
Genome-wide association studies (GWASs) of asthma have consistently implicated the ORM1-like 3 and gasdermin B (ORMDL3-GSDMB), IL33, IL-1 receptor–like 1 and IL-18 receptor 1 (IL1RL1-IL18R1), RAD50-IL13, thymic stromal lymphopoietin and WD repeat domain 36 region (TSLP-WDR36), and HLA-DR/DQ regions.
A GWAS of asthma was performed in a non-Hispanic white population.
A GWAS was performed in 813 Severe Asthma Research Program/Collaborative Studies on the Genetics of Asthma/Chicago Asthma Genetics Study cases and 1564 control subjects. The GWAS results were compared with those of the published GWASs of autoimmune diseases.
Multiple single nucleotide polymorphisms in the TNFAIP3 interacting protein 1 (TNIP1) gene, which interacts with TNFAIP3 and inhibits the TNF-α–induced nuclear factor κB inflammation pathway, were associated with asthma: rs1422673 (P = 3.44 × 10−7) and rs10036748 (P = 1.41 × 10−6, r2 = 0.67). rs1422673 was also associated with asthma in the published GABRIEL (P = .018) and EVE (P = 1.31 × 10−5) studies. The minor allele T of rs20541 in IL13 is the risk allele for asthma but the protective allele for psoriasis. The minor allele T of rs2395185 in HLA-DRA is the risk allele for asthma but the protective allele for ulcerative colitis. The minor allele A of rs2872507 in GSDMB is the protective allele for asthma but the risk allele for rheumatoid arthritis, Crohn disease, and ulcerative colitis. The T allele of rs10036748 in the TNIP1 gene is the minor protective allele for asthma but the minor or major risk allele for systemic lupus erythematosus and systemic sclerosis in non-Hispanic white or Chinese subjects, respectively.
Our study suggests that single nucleotide polymorphisms associated with both asthma and autoimmune diseases might have opposite effects on immunopathogenesis. (J Allergy Clin Immunol 2012;130:861-8.)
Asthma; genetics; genome-wide association study; TNFAIP3 interacting protein 1
Thymic stromal lymphopoietin (TSLP) is produced by epithelial cells and triggers dendritic cell-mediated Th2-type inflammation. While TSLP is upregulated in epithelium of patients with asthma, the factors that control TSLP production have not been studied extensively. Because mouse models suggest roles for protease(s) in Th2-type immune responses, we hypothesized that proteases from airborne allergens may induce TSLP production in a human airway epithelial cell line, BEAS-2B. TSLP mRNA and protein were induced when BEAS-2B cells were exposed to prototypic proteases, namely trypsin and papain. TSLP induction by trypsin required intact protease activity and also a protease-sensing G protein-coupled receptor, protease-activated receptor (PAR)-2; TSLP induction by papain was partially dependent on PAR-2. In humans, exposure to ubiquitous airborne fungi, such as Alternaria, is implicated in the development and exacerbation of asthma. When BEAS-2B cells or normal human bronchial epithelial cells were exposed to Alternaria extract, TSLP was potently induced. The TSLP-inducing activity of Alternaria was partially blocked by treating the extract with a cysteine protease inhibitor, E64, or by infecting BEAS-2B cells with small interfering RNA for PAR-2. Protease-induced TSLP production by BEAS-2B cells was enhanced synergistically by IL-4 and abolished by IFN-γ. These findings demonstrate that TSLP expression is induced in airway epithelial cells by exposure to allergen-derived proteases and that PAR-2 is involved in the process. By promoting TSLP production in the airways, proteases associated with airborne allergens may facilitate the development and/or exacerbation of Th2-type airway inflammation, particularly in allergic individuals.
Humans; cytokines; allergy; inflammation; lung
An important immunopathological hallmark of allergic disease is tissue eosinophilic and basophilic inflammation, a phenomenon which originates from hemopoietic progenitors (HP). The fate of HP is determined by local inflammatory cytokines that permit “in situ hemopoiesis,” which leads to the accumulation of eosinophils and basophils (Eo/B). Given that recent evidence supports a critical immunomodulatory role for thymic stromal lymphopoietin (TSLP) in allergic inflammation, as well as TSLP effects on CD34+ progenitor cytokine and chemokine secretion, we investigated the role of TSLP in mediating eosinophilo- and basophilopoiesis, the mechanisms involved, and the association of these processes with atopic sensitisation. In the studies presented herein, we demonstrate a direct role for TSLP in Eo/B differentiation from human peripheral blood CD34+ cells. In the presence of IL-3, TSLP significantly promoted the formation of Eo/B colony forming units (CFU) (including both eosinophils and basophils) from human HP (HHP), which was dependent on TSLP–TSLPR interactions. IL-3/TSLP-stimulated HHP actively secreted an array of cytokines/chemokines, key among which was TNFα, which, together with IL-3, enhanced surface expression of TSLPR. Moreover, pre-stimulation of HHP with IL-3/TNFα further promoted TSLP-dependent Eo/B CFU formation. HHP isolated from atopic individuals were functionally and phenotypically more responsive to TSLP than those from nonatopic individuals. This is the first study to demonstrate enhanced TSLP-mediated hemopoiesis ex vivo in relation to clinical atopic status. The capacity of HHP to participate in TSLP-driven allergic inflammation points to the potential importance of “in situ hemopoiesis” in allergic inflammation initiated at the epithelial surface.
Atopy; eosinophil–basophil progenitors; hemopoiesis; IL-3; TSLP
Severe refractory atopic dermatitis (AD) is a chronic, debilitating condition that is associated with elevated serum immunoglobulin E (IgE) levels. Thymic stromal lymphopoietin (TSLP), thymus and activation-regulated chemokine (TARC) and OX40 ligand (OX40L) are important immunologic factors involved in the pathogenesis of AD. Omalizumab, an anti-IgE antibody indicated for use in allergic asthma, is implicated in regulating allergen presentation by dendritic cells and the T cell response during the effector phases of allergic disease. We investigated if anti-IgE therapy modulates the allergen-specific responses mediated by the TSLP pathway in young patients with severe refractory AD.
This was a randomized, double-blind, placebo-controlled study of 8 patients between the ages of 4 and 22 years (mean = 11.6 years) with severe refractory AD (clinical trials.gov NCT01678092). Serum IgE ranged from 218 to 1,890 (mean = 1,068 IU/ml). Subjects received omalizumab (n = 4) or placebo (n = 4) every 2–4 weeks over 24 weeks using a regimen extrapolated from the package insert. TSLP, TARC, OX40L and other cytokines involved in AD were measured by using cytometric bead arrays.
All patients receiving omalizumab had strikingly decreased levels of TSLP, OX40L, TARC (involved in Th2 polarization) and interleukin (IL)-9 compared to placebo. In addition, there was a marked increase in IL-10, a tolerogenic cytokine, in the omalizumab-treated group. Patients on anti-IgE therapy had an improvement in clinical outcomes as measured by the SCORAD system; however, these effects were comparable to improvements in the control group.
Anti-IgE therapy with omalizumab decreases levels of cytokines that are involved in Th2 polarization and allergic inflammation, including TSLP, TARC and OX40L.
Atopic dermatitis; Immunoglobulin E; Omalizumab; Cytokine expression
The epithelial-derived cytokine thymic stromal lymphopoietin (TSLP) plays a key role in the development and progression of atopic disease and has notably been shown to directly promote the allergic inflammatory responses that characterize asthma. Current models suggest that TSLP is produced by epithelial cells in response to inflammatory stimuli and acts primarily upon dendritic cells to effect a T helper type 2-type inflammatory response. Recent reports, however, have shown that epithelial cells themselves are capable of expressing the TSLP receptor (TSLPR), and may thus directly contribute to a TSLP-dependent response. We report here that beyond simply expressing the receptor, epithelial cells are capable of dynamically regulating TSLPR in response to the same inflammatory cues that drive the production of TSLP, and that epithelial cells produce chemokine C–C motif ligand 17, a T helper type 2-associated chemokine, in response to stimulation with TSLP. These data suggest that a direct autocrine or paracrine response to TSLP by epithelial cells may initiate the initial waves of chemotaxis during an allergic inflammatory response. Intriguingly, we find that the regulation of TSLPR, unlike TSLP, is independent of nuclear factor kappa-light-chain-enhancer of activated B cells, suggesting that the cell may be able to independently regulate TSLP and TSLPR levels in order to properly modulate its response to TSLP. Finally, we show evidence for this dynamic regulation occurring following the viral infection of primary epithelial cells from asthmatic patients. Taken together, the data suggest that induction of TSLPR and a direct response to TSLP by epithelial cells may play a novel role in the development of allergic inflammation.
TSLP; TSLPR; RSV; asthma; epithelium
Thymic stromal lymphopoietin (TSLP) is an interleukin 7 (IL-7)-like cytokine expressed mainly by epithelial cells. Current studies provide compelling evidence that TSLP is capable of activating dendritic cells (DCs) to promote T helper (Th) 2 immune responses. TSLP has also been shown to directly promote Th2 differentiation of naïve CD4+ T cell, and activate natural killer T (NKT) cells, basophils and other innate immune cells at the initial stage of inflammation. In addition, TSLP affects B cell maturation and activation, and can also influence regulatory T (Treg) cell differentiation and development. TSLP-induced Th2 responses are associated with the pathogenesis of allergic inflammatory diseases, including atopic dermatitis (AD), asthma and rhinitis. Based on recent findings in humans and mouse models, TSLP might also be involved in the pathogenesis of inflammatory bowel disease and progression of cancer. In this review, we will summarize our current understanding of the biology of TSLP, and highlight the important issues for future investigations.
TSLP; allergy; Th2; cancer; inflammation