Induced Thymic Stromal Lymphopoietin Expression Research Articles

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

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

Evidence that oncostatin M synergizes with IL-4 signaling to induce TSLP expression in chronic rhinosinusitis with nasal polyps

Oncostatin M (OSM) may promote type 2 inflammation in chronic rhinosinusitis with nasal polyps (CRSwNP) by inducing thymic stromal lymphopoietin (TSLP). We sought to study the impact of OSM on TSLP synthesis and release from nasal epithelial cells (NECs). OSM receptors, IL-4 receptors (IL-4R), and TSLP were evaluated in mucosal tissue and primary NECs from patients with CRSwNP by quantitative PCR and immunofluorescence. Air-liquid interface-cultured NECs were stimulated with cytokines, including OSM, and quantitative PCR, ELISA, Western blot, and flow cytometry were used to assess the expression of OSM receptors, IL-4R, and TSLP. Increased levels of OSM receptor β chain (OSMRβ), IL-4Rα, and TSLP were observed in nasal polyp tissues and primary epithelial cells from nasal polyps of patients with CRSwNP compared with control tissues or cells from control subjects. The level of expression of OSMRβ in tissue was correlated with levels of both IL-4Rα and TSLP. OSM stimulation of NECs increased the expression of OSMRβ and IL-4Rα. Stimulation with IL-4 plus OSM augmented the production of TSLP; the response was suppressed by a signal transducer and activator of transcription 6 inhibitor. Stimulation of NECs with IL-4 plus OSM increased the expression of proprotein convertase subtilisin/kexin 3, an enzyme that truncates and activates TSLP. OSM increases the expression of IL-4Rα and synergizes with IL-4 to induce the synthesis and release of TSLP in NECs. Because the combination of IL-4 and OSM also augmented the expression of proprotein convertase subtilisin/kexin 3, these results suggest that OSM can induce both synthesis and posttranslational processing/activation of TSLP, promoting type 2 inflammation.

Phloxine O, a Cosmetic Colorant, Suppresses the Expression of Thymic Stromal Lymphopoietin and Acute Dermatitis Symptoms in Mice.

Cosmetics are primarily applied to the skin; therefore, the association of cosmetic dyes with skin diseases or inflammation is a topic of great interest. Thymic stromal lymphopoietin (TSLP) is an interleukin 7-like cytokine that activates dendritic cells to promote Th2 inflammatory immune responses. TSLP is highly expressed in keratinocytes under inflammatory conditions, which suggests that it may play a critical role in the development of skin diseases, such as atopic dermatitis. Therefore, we investigated whether cosmetic dyes influenced the production of TSLP by keratinocytes. Phloxine O, also known as D&C Red No.27, is one of the most common red synthetic pigments and is widely used in colored cosmetics. Our results showed that Phloxine O downregulated phorbol 12-myristate 13-acetate-induced production of TSLP in a murine keratinocyte cell line (PAM212). Phloxine O also suppressed TSLP expression in KCMH-1 cells, which are mouse keratinocytes that constitutively produce high levels of TSLP. To investigate the in vivo effects of Phloxine O, we induced TSLP expression in mouse ear skin by topically applying MC903, a vitamin D3 analogue that is a well-known inducer of atopic dermatitis-like symptoms. Topical application of Phloxine O prevented MC903-induced TSLP production in mouse ear skin, attenuated the acute dermatitis-like symptoms and decreased serum IgE and histamine levels in mice. Suppression of TSLP expression by Phloxine O correlated with reduced expression of OX40 ligand and Th2 cytokines in mouse ear skin. Our results showed that Phloxine O may be beneficial to prevent dermatitis by suppressing the expression of TSLP and Th2 cytokines in skin.

Sebaceous Gland-Rich Skin Is Characterized by TSLP Expression and Distinct Immune Surveillance Which Is Disturbed in Rosacea

The microbial community exhibits remarkable diversity on topographically distinct skin regions, which may be accompanied by differences in skin immune characteristics. Our aim was to compare the immune milieu of healthy sebaceous gland-rich (SGR) and sebaceous gland-poor skin areas, and to analyze its changes in an inflammatory disease of SGR skin. For this purpose, immunohistochemical, immunocytochemical, and quantitative real-time PCR analyses of thymic stromal lymphopoietin (TSLP) and other cytokines, phenotypic immune cell markers and transcription factors were carried out in samples from sebaceous gland-poor, SGR skin and from papulopustular rosacea. TSLP mRNA and protein production was also studied in cultured keratinocytes. In SGR skin, higher TSLP expression, dendritic cell appearance without prominent activation, and T cell presence with IL-17/IL-10 cytokine milieu were detected compared with sebaceous gland-poor skin. Linoleic acid, a major sebum component, was found to induce TSLP expression dose-dependently in keratinocytes. In papulopustular rosacea, significantly decreased TSLP level and influx of inflammatory dendritic cells and T cells with IL-17/interferon-γ cytokine milieu were observed. According to our results, SGR skin is characterized by a distinct, noninflammatory immune surveillance, which may explain the preferred localization of inflammatory skin diseases, and can influence future barrier repair therapeutic concepts.

Inhibitory effects of nicotine derived from cigarette smoke on thymic stromal lymphopoietin production in epidermal keratinocytes

Thymic stromal lymphopoietin (TSLP) is regarded as the main factor responsible for the pathogenesis of atopic dermatitis (AD). Cigarette smoke is an aggravating factor for allergies, but has been reported to decrease the risk of AD. In the present study, we evaluated the role of nicotine, the main constituent in cigarette smoke extract, and its underlying mechanism of action in the regulation of TSLP expression. We found that nicotine significantly inhibited 12-O-tetradecanoylphorbol-13-acetate (TPA)-induced TSLP expression in BALB/c mice and the mouse keratinocyte cell line PAM212. Nicotine inhibition of TSLP production was abolished by pretreatments with α7 nicotinic acetylcholine receptor (α7 nAChR) antagonists, AMP-activated protein kinase (AMPK) inhibitor, and phosphoinositide 3-kinase (PI3K) inhibitors. The same inhibitors abolished inhibition of nuclear factor-κB (NF-κB) activation by nicotine. These results suggest that nicotine inhibits the expression of TSLP by suppressing the activation of NF-κB through the α7 nAChR–PI3K–AMPK signaling pathway.

IL-33 induces Egr-1-dependent TSLP expression via the MAPK pathways in human keratinocytes.

Atopic dermatitis (AD) is a chronic inflammatory skin disease in which T-helper type 2 (Th2)-type immune responses are dominant. Th2 cytokine, interleukin (IL)-33 and thymic stromal lymphopoietin (TSLP) have been suggested to have an important role in AD. IL-33 is highly expressed in AD, but its role in AD has not yet been fully understood. To further identify the role of IL-33 in AD, we investigated the expression of TSLP induced by IL-33 in keratinocytes. This study revealed that IL-33 induced TSLP expression in human keratinocytes. Early growth response protein 1 (Egr)-1, which is an inflammatory transcriptional factor, is induced by IL-33. IL-33-mediated TSLP induction in keratinocytes was suppressed by treatment with mitogen-activated protein kinase (MAPK) inhibitors or small interfering RNA against Egr-1. Chromatin immunoprecipitation (ChIP) assay indicated the direct involvement of Egr-1 in IL-33-mediated TSLP induction. Taken together, these findings indicate that IL-33 may increase TSLP expression through an Egr-1-dependent mechanism via ERK1/2, JNK and p38 activation in keratinocytes. These data suggest that the IL-33-ERK/JNK/p38/Egr-1/TSLP axis is involved in allergic skin Th2 inflammation, and it may be a novel therapeutic target.

Effect of Sodium Lauryl Sulfate on Thymic Stromal Lymphopoietin mRNA and Protein Expression in Human Keratinocytes In Vitro.

Atopic dermatitis (AD) is a chronic inflammatory skin disease with a Th2/Th22 polarization. The prevalence of AD increased over the last few decades (DaVeiga, 2012). It is noted that the prevalence of AD is associated with the modern environment, especially with the industrialization development (Hoffjan and Epplen, 2005). Thymic stromal lymphopoietin (TSLP) has been found to have roles in AD (Soumelis et al., 2002). More recently, it was reported that injury in stratum corneum by topical sodium lauryl sulfate (SLS) could induce TSLP expression (Angelova-Fischer et al., 2010). Environmental factors may also induce TSLP expression, and TSLP is considered as a mediator linking environmental stimuli and host response (Takai, 2012).

Role of licochalcone A on thymic stromal lymphopoietin expression: implications for asthma.

Asthma is a common chronic inflammatory disease characterized by the infiltration and accumulation of memory-like Th2 cells and eosinophils. Viral infection has emerged as the most common cause of severe episodes of asthma. For the treatment of bronchial asthma, the root of liquorice (Glycyrrhiza glabra) has been used as a traditional medicine in the East and West. Licochalcone A is the predominant, characteristic chalcone in liquorice root. To determine whether licochalcone A possesses an anti-inflammatory effect, we tested its effect on the expression and production of thymic stromal lymphopoietin (TSLP) in BEAS 2B cells and primary bronchial epithelial cells. We found that polyinosinic-polycytidylic acid (poly-IC)-induced TSLP expression was suppressed by treatment with licochalcone A in a dose- and time-dependent manner. We also found that poly-IC-induced mRNA expression of other proinflammatory mediators such as MCP-1, RANTES, and IL-8 was suppressed by licochalcone A. Furthermore, licochalcone A suppressed poly-IC-induced nuclear factor kappa B (NF-κB) nuclear translocation and DNA-binding activity by suppressing the Iκβ kinase (IKK) activity but not by direct phosphorylation of p65 at serine 276. Collectively, our findings suggest that licochalcone A suppresses poly-IC-induced TSLP expression and production by inhibiting the IKK/NF-κB signaling pathway, which might be involved in the pathogenesis of virus-exacerbated asthma. Further elucidation of the mechanisms underlying these observations can help develop therapeutic strategies for virally induced asthma.

UVB Induces HIF-1α-Dependent TSLP Expression via the JNK and ERK Pathways

Thymic stromal lymphopoietin (TSLP) may have a key role in the initiation and maintenance of allergic inflammatory diseases, including atopic dermatitis. The present study revealed that UVB radiation exposure could induce TSLP expression in human keratinocytes and a human skin equivalent model. In addition, we investigated the regulatory mechanism of UVB-induced TSLP expression in keratinocytes. TSLP expression was upregulated by transfection with pcDNA3-hypoxia-inducible factor (HIF)-1α (P402A and P564A), which stably expresses HIF-1α protein. UVB-induced TSLP induction in keratinocytes was suppressed in the treatment of mitogen-activated protein kinase inhibitors or small interfering RNAs against HIF-1α. The results of chromatin immunoprecipitation assays indicate the direct involvement of HIF-1α in UVB-mediated TSLP induction. Taken together, these findings indicate that UVB exposure may increase TSLP expression through a HIF-1α-dependent mechanism via the c-JUN N-terminal kinase and extracellular signal-regulated kinase pathways in human keratinocytes. Our data showed that UVB-induced TSLP might increase secretion of the T-helper type 2-attracting chemokine (c-c motif) ligand 17 by human dendritic cells. The present study suggests an important role of HIF-1α in UVB-mediated immune response in keratinocytes.

Induction of thymic stromal lymphopoietin expression in 16-HBE human bronchial epithelial cells by 25-hydroxyvitamin D3 and 1,25-dihydroxyvitamin D3

Vitamin D exerts profound effects on airway epithelial cells. Thymic stromal lymphopoietin (TSLP) derived from airway epithelial cells plays a role in the innate and antigen‑specific adaptive immune responses. However, the effect of vitamin D on TSLP expression in airway epithelial cells is unclear. In this study, 16-HBE human bronchial epithelial (HBE) cells were cultured with various concentrations of 25-hydroxyvitamin D(3) (25 D(3)) and 1,25-dihydroxyvitamin D(3) (1,25 D(3)). The expression of TSLP in the 16-HBE human bronchial epithelial cell line was analyzed by PCR and enzyme-linked immunosorbent assay (ELISA). We found that the 16-HBE cells converted inactive 25 D(3) to active 1,25 D(3) and that TSLP mRNA and protein expression levels were significantly increased, peaking at 2 or 12 h in the cells exposed to 500 nM 25 D(3) and 50 nM 1,25 D(3) respectively. Since vitamin D(3) upregulated protein 1 (VDUP1) plays a multifunctional role in a variety of cellular responses, we hypothesized that VDUP1 is involved in the induction of TSLP production by 25 D(3). The results showed that the mRNA and protein levels of VDUP1 were significantly upregulated by vitamin D. Furthermore, the silencing of VDUP1 by small interfering RNA (siRNA) significantly inhibited the 25 D(3)- and 1,25 D(3)-mediated induction of TSLP expression. To characterize the metabolic properties of vitamin D in airway epithelial biology, we used the chemical inhibitor of 1α-hydroxylase, itraconazole. The results revealed that itraconazole (10-6 M) reduced the 25 D(3)- but not the 1,25 D(3)-induced TSLP expression in 16-HBE cells. Based on these data, it can be concluded that vitamin D increases TSLP expression in 16-HBE cells through the VDUP1 pathway, which suggests a novel mechanism by which vitamin D alters immune function in the lungs.

Endogenous TGF‐β activity limits TSLP expression in the intervertebral disc tissue by suppressing NF‐κB activation

Thymic stromal lymphopoietin (TSLP), an IL-7-like cytokine, is highly expressed in herniated disc (HD) tissue and may act as a key molecule for the initiation of macrophage recruitment into the tissue and natural resorption of HD. However, it remains unclear how TSLP expression is regulated in the intervertebral discs. This study showed that expression of TSLP and phosphorylated NF-κB in HD tissue samples was inversely correlated with expression of phosphorylated Smad2/3 (an indicator of active TGF-β signaling) and vice versa in posterior lumbar spinal fusion samples. The pharmacological blockades of endogenous TGF-β activity induced TSLP expression in mouse intervertebral disc tissue culture, which was inhibited by NF-κB inhibitors. Additionally, phosphorylation of Smad2/3 was constitutively detected in mouse intervertebral disc tissue in the steady states. Collectively, these results suggest that endogenous TGF-β activity limits TSLP expression in intervertebral disc tissue in the steady states by suppressing NF-κB activation. The findings reveal a regulatory mechanism how TSLP expression is induced in the intervertebral disc tissue and suggest a novel role of TGF-β in maintaining the homeostasis of intervertebral disc tissue.

TARC is a potential marker for early indication of disease and prediction of disease activity in drug-induced hypersensitivity syndrome

Thymic stromal lymphopoietin (TSLP) is overexpressed in esional keratinocytes in atopic dermatitis (AD). The local increase n TSLP is associatedwith activation of dendritic cells which trigger he differentiation of naive CD4+T cells into proallergic CD4+Th2 ells. Thus, TSLP is thought to play an important role in the pathoenesis of AD, but the alteration of TSLP expression after treatment as not fully been understood. Here we investigated whether TSLP xpression in normal human epidermal keratinocytes (NHEKs) ould be affected by common clinical treatments including ultraiolet (UV) A and B, glucocorticosteroid, and calcineurin inhibitors. e first confirmed that TNF–alpha induced TSLP expression in HEKs by real–time PCR and ELISA. In addition, immunohistohemistry showed that TNF–alpha–positive cells were infiltrated n AD lesions. Next we observed that treatments of UVA (0.5, 1, 2, nd 5 J/cm2) significantly suppressed the induction of TSLP expresionby stimulationwithTNF-alpha (10ng/ml) in adose–dependent anner. A synthetic glucocorticosteroid dexamethasone (10−7, 0−6, and 10−5 M) and a calcineurin inhibitor tacrolimus (10−7, 0−6, and 10−5 M) also suppressed TSLP expression in NHEKs in dose–dependent manner. On the other hand, UVB (0.02, 0.04, .06, 0.08, and 0.1 J/cm2) induced TSLP expression in NHEKs. These echanisms might be associated with the clinical improvements nd further studies are needed to clarify the effects of UVB on TSLP xpression.

Flagellin Induces the Expression of Thymic Stromal Lymphopoietin in Human Keratinocytes via Toll-Like Receptor 5

Background: Thymic stromal lymphopoietin (TSLP), highly expressed by keratinocytes in skin lesions of atopic dermatitis patients and bronchial epithelial cells in asthma, plays a key role in allergic diseases. Information on triggers for the release of TSLP in keratinocytes is still limited. Keratinocytes express Toll-like receptor (TLR) 5, the ligand for which is flagellin, the major structural protein of the flagella of Gram-negative bacteria. IL-4, IL-13 and TNF-α (Th2/TNF) are associated with allergic diseases. TGF-α, one of the ligands for the epidermal growth factor receptor, is overexpressed in keratinocytes in atopic dermatitis. We investigated the induction of TSLP expression in keratinocytes stimulated with flagellin and its modulation by the Th2/TNF cytokines and TGF-α. Methods: Primary human keratinocytes were stimulated with flagellin with or without cytokines. The TSLP released was measured by ELISA. Gene expression was analyzed by quantitative real-time PCR. Results: Stimulation of keratinocytes with flagellin induced the release of TSLP protein and upregulation of the gene expression of TSLP and other pro-inflammatory molecules. The flagellin-induced release of TSLP was enhanced by the Th2/TNF cytokines or TGF-α. Small interfering RNA-mediated knockdown of TLR5 expression suppressed the flagellin-induced TSLP gene expression. Conclusions: Flagellin induces TSLP expression in keratinocytes via TLR5 and the expression can be upregulated by a cytokine milieu with Th2/TNF or TGF-α, suggesting that exposure of barrier-defective skin to Gram-negative bacteria or environmental flagellin contributes to the initiation and/or amplification of Th2-type skin inflammation including atopic dermatitis through the induction of TSLP expression in keratinocytes.

Staphylococcus aureus membrane and diacylated lipopeptide induce thymic stromal lymphopoietin in keratinocytes through the Toll-like receptor 2–Toll-like receptor 6 pathway

Staphylococcus aureus heavily colonizes the lesions of patients with atopic dermatitis (AD) and is known to trigger a worsening of AD. However, the exact mechanism by which S. aureus promotes AD is unknown. Thymic stromal lymphopoietin (TSLP), which is highly expressed by keratinocytes in skin lesions of patients with AD and bronchial epithelial cells in asthmatic patients, represents a critical factor linking responses at interfaces between the body and the environment to allergic type 2 immune responses. We sought to examine the ability of synthetic lipopeptides and S. aureus to induce TSLP expression in human keratinocytes and identify the pathway of induction. We stimulated primary human keratinocytes with lipopeptides and S. aureus-derived materials. The release and gene expression of TSLP were measured by means of ELISA and quantitative PCR, respectively. Diacylated lipopeptide upregulated the expression of TSLP and other proinflammatory molecules. Heat-killed S. aureus and the subcellular fractions of S. aureus induced TSLP's release, with the membranous fraction having the greatest activity. Small interfering RNA-mediated knockdown of either Toll-like receptor (TLR) 2 or TLR6 inhibited the diacylated lipopeptide- and S. aureus membrane-induced TSLP gene expression. S. aureus membrane- and diacylated lipopeptide-induced release of TSLP was enhanced by T(H)2/TNF-α cytokines and partially suppressed by IFN-γ and TGF-β. The results suggest that ligands for the TLR2-TLR6 heterodimer in S. aureus membranes, including diacylated lipoproteins, could promote T(H)2-type inflammation through TSLP production in keratinocytes, providing an overall picture of the vicious cycles between colonization by S. aureus and AD in the T(H)2-skewed sensitization process, exacerbation of the disease, or both.

Thymic stromal lymphopoietin is a critical mediator of IL‐13‐driven allergic inflammation

Both thymic stromal lymphopoietin (TSLP) and IL-13 are essential cytokines for the development of allergic inflammation. However, a causal link between TSLP and IL-13 has not yet been fully elucidated. This study aimed to investigate whether IL-13 induces TSLP expression and whether the induction contributes to the development of allergic inflammation. We found that IL-13 induced TSLP expression in mouse nasal tissue specimens in a Stat6-dependent manner. In addition, intranasal challenge of mice with IL-13 induced TSLP expression in the nasal epithelium. Importantly, intranasal IL-13 challenge induced eosinophilia and goblet cell hyperplasia in the nasal mucosa in mice, which was inhibited by the blockade of TSLP activity with anti-TSLP Ab. These findings suggest that TSLP is an important mediator of IL-13-driven allergic inflammation in the nasal mucosa. Taken together with the recent findings that IL-13 is a critical downstream element for TSLP-driven allergic inflammation, TSLP may function both upstream and downstream of IL-13, thus providing an additional rationale as to why TSLP plays such a central role in the development of allergic inflammation.

Proinflammatory Th2 Cytokines Induce Production of Thymic Stromal Lymphopoietin in Human Colonic Epithelial Cells

PurposeThymic stromal lymphopoietin (TSLP) is released by intestinal epithelial cells (IECs), and TSLP-conditioned dendritic cells appear to be involved in immune homeostasis of intestine and immunoglobulin A (IgA) class-switching in the physiological condition. In contrast, TSLP activates dendritic cells to induce strong T-cell proliferation and is involved in inflammatory T helper (Th) 2 responses in human allergic diseases. However, it is not clear how TSLP production by IECs is regulated in ulcerative colitis (UC), which appears to involve inflammatory Th2 responses. The aim of this study is to examine how TSLP production by IECs is regulated in ulcerative colitis.ResultsWe show here that expression of TSLP was enhanced in mucosal lesions from UC patients in which inflammatory Th2 cytokine production was predominant. In addition, using a human colonic epithelial cell line, we demonstrated that a combination of tumor necrosis factor-alpha (TNF-α) and interleukin-4 (IL-4) induced TSLP expression and that TSLP expression by TNF-α + IL-4 was further enhanced by either Toll-like receptor 3 ligand or interferon (IFN)-γ.ConclusionsTaken together, as in human allergic diseases, an inflammatory Th2 condition in the mucosal lesions of UC patients may trigger increased TSLP expression by IECs, resulting in exacerbation of UC.

Identification of TSLP-dependent mediators in a calcipotriol (Dovonex®) driven mouse model of skin inflammation (140.16)

Abstract The epithelial-derived cytokine thymic stromal lymphopoietin (TSLP) is sufficient to induce asthma or atopic dermatitis (AD)-like phenotypes when selectively overexpressed in transgenic mice. Although T and B cells have been reported to be dispensable for the TSLP-induced inflammation in these models, little is known about the downstream pathways or mediators involved in the inflammatory response driven by TSLP. Topical treatment with vitamin D3 (1α,25-(OH)2D3) or MC903, the low-calcemic analog of vitamin D3, has been shown to induce TSLP expression in epidermal keratinocytes. This induction resulted in an AD-like phenotype similar to that seen in TSLP transgenic mice. 0.005% calcipotriol (Dovonex®) is a synthetic, low-calcemic vitamin D3 analog which is FDA-approved for the treatment of psoriasis. Following topical application of Dovonex® onto mouse ears, TSLP mRNA expression increased over time. Concomitant increases in CCL17/TARC, CCL22/MDC, and IL-6 mRNA were also observed. These increases were dependent on TSLP as an antibody that blocked TSLP signaling abrogated the response. Similarly, a variety of TSLP-dependent protein analytes were increased in the skin following application of Dovonex®. Together these data identify TSLP-dependent mediators that may play a role in the development of skin inflammatory diseases such as atopic dermatitis.

Human Corneal Epithelium-Derived Thymic Stromal Lymphopoietin Links the Innate and Adaptive Immune Responses via TLRs and Th2 Cytokines

To explore the crucial role of the human corneal epithelium-derived proallergic cytokine thymic stromal lymphopoietin (TSLP) in initiation and regulation of immune responses. Primary corneal epithelial cells, established from donor limbal explants, were treated with 11 microbial ligands and proinflammatory and Th2 cytokines, alone or in combination. TSLP mRNA and protein were determined by real-time PCR and ELISA, respectively. NF-kappaB activation was detected by immunostaining and Western blot. TSLP was found to be expressed by human corneal epithelium and its cultures. TSLP in corneal epithelial cells were largely induced in a concentration-dependent fashion by polyI:C, flagellin, and FSL-1, the ligands for toll-like receptor (TLR)-3, -5, and -6, respectively. Compared with the control, TSLP mRNA was increased by 60-, 12- and 8-fold and TSLP protein increased by 67-, 19- and 7-fold by these three ligands, respectively. The proinflammatory (TNF-alpha and IL-1beta) and Th2 (IL-4 and IL-13) cytokines moderately induced TSLP expression and production. IL-4 and -13 strongly synergized with PolyI:C, flagellin, and TNF-alpha to promote TSLP production in ex vivo tissues and in vitro cultures of corneal epithelium. PolyI:C, flagellin, or TNF-alpha also induced NF-kappaB p65 protein nuclear translocation. The NF-kappaB inhibitor quinazoline blocked p65 nuclear translocation and further suppressed TSLP expression and production induced by these stimuli. These findings provide the first evidence of TSLP induction in the human eye and suggest the novel phenomenon that human corneal epithelium-derived TSLP may serve as a link between the innate and adaptive immune responses. TSLP may become a novel therapeutic target for allergic and inflammatory ocular surface diseases.

Cigarette smoke extract induces thymic stromal lymphopoietin expression, leading to T H2-type immune responses and airway inflammation

Both active and passive smoking are considered to be risk factors for asthma development. However, the precise mechanisms involved remain elusive. Recently, thymic stromal lymphopoietin (TSLP) has been shown to play a key role in the development of T(H)2-type allergic inflammation in patients with asthma. The aim of this study was to investigate whether there was a causal relationship between cigarette smoke exposure and TSLP expression in the lung. We examined the effects of repeated intranasal exposure of cigarette smoke extract (CSE) on TSLP mRNA and protein expression in the mouse lung by means of real-time PCR, Western blotting, and immunohistochemistry. We also examined the effects of intranasal exposure of CSE plus ovalbumin (OVA) on T(H)2-type immune responses and lung pathology. Repeated exposure of CSE induced TSLP mRNA and protein expression, which was inhibited by treatment with antioxidative N-acetylcysteine and by TNF-alpha receptor I deficiency. In addition, the intranasal exposure of CSE simultaneously with OVA induced OVA-specific T(H)2-type immune responses and airway inflammation, which were inhibited by the blockade of the TSLP activity. CSE induced TSLP expression in the mouse lung in an oxidative stress-dependent and TNF-alpha receptor I-dependent manner, and when challenged simultaneously with an antigen, CSE promoted the development of airway inflammation in association with T(H)2-type immune responses.

Mast cell regulation of epithelial TSLP expression plays an important role in the development of allergic rhinitis

Epithelial cell-derived thymic stromal lymphopoietin (TSLP) is a master switch for asthma or atopic dermatitis by inducing a dendritic cell-mediated Th2-type allergic inflammation. Allergic rhinitis is also pathologically characterized by Th2-type allergic inflammation. This study demonstrates that mast cells regulate the epithelial TSLP expression in allergic rhinitis. TSLP expression was found to be up-regulated predominantly in the nasal epithelium in the ovalbumin (OVA)-sensitized and -nasally challenged mouse model of allergic rhinitis, which was abolished in mast cell-deficient WBB6F1-W/W(v) in comparison with control WBB6F1-+/+ mice. Similarly, the epithelial TSLP expression was reduced in Fc receptor gamma chain (FcgammaR)-deficient mice, where the high-affinity IgE receptor (FcepsilonRI) is not expressed on mast cells, in comparison with control C57BL/6 mice. Furthermore, the administration of neutralizing TSLP antibody during the challenge phase of OVA inhibited the development of allergic rhinitis. These results suggest that the direct stimulation of epithelial cells by antigens alone may not be sufficient to induce TSLP expression in the nasal epithelium, and that mast cell regulation of epithelial TSLP expression, possibly via FcepsilonRI, plays an important role in the development of allergic rhinitis.