A potential link between TSLP/TSLPR/STAT5 and TLR2/MyD88/NFκB-p65 in human corneal epithelial cells for Aspergillus fumigatus tolerance

Thymic stromal lymphopoietin participates in the host response to intra-amniotic inflammation leading to preterm labor and birth

The aim of this study was to establish the role of thymic stromal lymphopoietin (TSLP) in the intra-amniotic host response of women with spontaneous preterm labor (sPTL) and birth. Amniotic fluid and chorioamniotic membranes (CAM) were collected from women with sPTL who delivered at term (n = 30) or preterm without intra-amniotic inflammation (n = 34), with sterile intra-amniotic inflammation (SIAI, n = 27), or with intra-amniotic infection (IAI, n = 17). Amnion epithelial cells (AEC), Ureaplasma parvum, and Sneathia spp. were also utilized. The expression of TSLP, TSLPR, and IL-7Rα was evaluated in amniotic fluid or CAM by RT-qPCR and/or immunoassays. AEC co-cultured with Ureaplasma parvum or Sneathia spp. were evaluated for TSLP expression by immunofluorescence and/or RT-qPCR. Our data show that TSLP was elevated in amniotic fluid of women with SIAI or IAI and expressed by the CAM. TSLPR and IL-7Rα had detectable gene and protein expression in the CAM; yet, CRLF2 was specifically elevated with IAI. While TSLP localized to all layers of the CAM and increased with SIAI or IAI, TSLPR and IL-7Rα were minimal and became most apparent with IAI. Co-culture experiments indicated that Ureaplasma parvum and Sneathia spp. differentially upregulated TSLP expression in AEC. Together, these findings indicate that TSLP is a central component of the intra-amniotic host response during sPTL.

Nonylphenol exacerbates ovalbumin-induced allergic rhinitis via the TSLP-TSLPR/IL-7R pathway and JAK1/2-STAT3 signaling in a mouse model

Nonylphenol (NP) can be widely used as a plasticizer, surfactant, antioxidant, textile printing, dyeing additive, and pesticide emulsifier. Animal studies have shown that NP aggravates ovalbumin (OVA)-induced allergic rhinitis (AR); however, the exact mechanism underlying its action has not yet been detailed. This study aimed to explore the aggravation of the AR inflammatory response following NP exposure and its possible mechanism. The AR mouse model was constructed using OVA. Under NP exposure, allergic nasal symptoms were observed, eosinophil infiltration was assessed by Sirius red staining, and the levels of IL-4, IL-5, and IL-13 in nasal mucosa samples were detected using cytometric bead array. The mRNA levels of OX40/OX40L and GATA3 in nasal mucosa were detected by qPCR, and the expression levels of the TSLP and JAK1/2-STAT3 signaling pathway components were also identified. Our results suggest that NP exposure exacerbated allergic nasal symptoms and that eosinophils accumulated in nasal mucosa after OVA challenge. The levels of the typical T helper 2 cytokines, as well as the mRNA levels of OX40/OX40L and GATA3, were elevated in the nasal mucosa of OVA-challenged mice exposed to NP. In addition, NP exposure elevated the TSLP, TSLPR, IL-7R, p-JAK1, p-JAK2, and p-STAT3 levels in the nasal mucosa after OVA stimulation. Overall, the present study suggests NP can exacerbate OVA-induced AR inflammatory responses; furthermore, this aggravating effect of NP may be related to the TSLP-TSLPR/IL-7R and JAK1/2-STAT3 signaling pathways.

Resolvin D1 protects against Aspergillus fumigatus keratitis in diabetes by blocking the MAPK-NF-κB pathway

Fungal keratitis (FK) is one of the main causes of blindness in China. People with diabetes are susceptible to corneal epithelial disease, even fungal keratitis. At present, there are few studies on this disease. Resolvins (Rv) has been reported as a mediators that exert crucial anti-inflammatory and immune regulation roles in serval diseases. In order to investigate the roles and underlying mechanism of Resolvins D1 (RvD1) on the Aspergillus fumigatus (A. fumigatus) keratitis in diabetes, we established in vivo and in vitro models of A. fumigatus keratitis, which were then exposed to high glucose. The expression levels of RvD1, 5-lipoxygenase (5-LOX), and 15-lipoxygenase (15-LOX) in A. fumigatus keratitis patients with diabetes were determined through Enzyme Linked Immunosorbent Assay (ELISA), Western blot and immunohistochemistry. Reactive Oxygen Species (ROS) production, ELISA, flow cytometry, Hematoxylin-Eosin (HE) staining and fungal loading determination were conducted to evaluate the severity of A. fumigatus infection. Lymphangiogenesis and angiogenesis were examined by immunofluorescence assay. Western blot was applied to detect the proteins of the MAPK-NF-κB pathway. The results showed that RvD1 diminished the high glucose-induced oxidative stress and inflammatory response, as evidenced by the reduction of ROS production, Interleukin-6 (IL-6), Interleukin-8 (IL-8), Heme Oxygenase-1 (HMOX-1), and the elevation of Cyclooxygenase-2 (COX2), Superoxide Dismutase (SOD-1), and Glutathione Peroxidase-2 (GPX2) levels in A. fumigatus-infected Human Corneal Endothelial Cells (HCECs). Additionally, lymphangiogenesis and angiogenesis prominently decreased after intervention with RvD1. Furthermore, RvD1 significantly reduced the levels of p-MEK1/2 and p-ERK1/2, and restrained the NF-κB and GPR32 activation. The above results showed that RvD1 protects against A. fumigatus keratitis in diabetes by suppressing oxidative stress, inflammatory response, fungal growth, and immunoreaction via modulating MAPK-NF-κB pathway. RvD1 provides clues for the therapeutic targets of Fungal keratitis complicated with diabetes.

The correlation between single nucleotide polymorphisms of the thymic stromal lymphopoietin receptor and breast cancer in a cohort of female patients in Saudi Arabia

The current study aimed to examine thymic stromal lymphopoietin receptor (TSLPR) genetic variation and breast cancer (BC) susceptibility in women in Saudi Arabia. Therefore, 127 blood samples from female patients diagnosed with BC and 116 blood samples from healthy female controls were studied using a genotyping assay to determine the association between three TSLPR single nucleotide polymorphisms (SNPs)-P196L, X201W, and A238V-and the risk of BC progression. In addition, gene expression was evaluated in 20 matching BC and normal tissues using immunohistochemistry. TSLPR protein levels were higher among BC patients than those with matching normal breast tissue. In addition, TSLPR SNP P196L was found to have a significant protective effect on BC progression (OR = 0.4427), although only the T allele for TSLPR P196L had this protective effect against BC progression in participants who were younger than 48 years old. In contrast, no association was found between the T allele and risk of BC in participants who were older than 48 years old, and the CT and TT genotypes were significantly associated with BC risk protection in the older group. The effects of the TT genotype and the T allele were closely associated with a decreased risk of BC in participants with estrogen receptors (ER+) and without them (ER-). Overall, the findings revealed a significant correlation between SNPs in the TSLPR genes and BC progression among women in Saudi Arabia.

Interactions of thymic stromal lymphopoietin with interleukin-4 in adaptive immunity during Aspergillus fumigatus keratitis

AIM

To investigate the potential interactions of thymic stromal lymphopoietin (TSLP) with interleukin-4 (IL-4) in adaptive immunity during fungal keratitis (FK).

METHODS

An FK mouse model was induced with Aspergillus fumigatus (AF) hyphal infection. Mice were divided into several groups: untreated, phosphate buffer saline (PBS), infected with AF, and pretreated with a scrambled siRNA, a TSLP-specific siRNA (TSLP siRNA), murine recombinant TSLP (rTSLP), immunoglobulin G (IgG), murine recombinant IFN (rIFN-γ), murine recombinant IL-4 (rIL-4), rIL-13, murine recombinant IL-17A (rIL-17A), and murine recombinant IL-17F (rIL-17F) groups. Quantitative real-time reverse transcription-polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA) or Western blot were performed to determine mRNA and protein levels in the inflamed cornea. Cytokine locations were observed by immunofluoresence staining after AF hyphal infection.

RESULTS

Compared to those in the untreated group, TSLP and T helper type 1 (Th1) cytokine levels in the AF group were upregulated at 24h post infection (hpi), and those of T helper type 2 (Th2) and T helper type 17 (Th17) cytokines were increased at 5d post infection (dpi). Th2 cytokine levels were decreased in the TSLP siRNA-pretreated group and increased in the rTSLP-pretreated group compared with the AF group. The TSLP level was increased in the rIL-4-pretreated group, but there were no significant changes among the other groups. Immunofluorescence staining showed cytokine locations after AF hyphal infection.

CONCLUSION

TSLP induces a Th2 immune response and promots Th2 T cell differentiation in vivo. IL-4 promotes TSLP secretion. Therefore, TSLP with IL-4 regulates adaptive immunity in FK.

Thymic stromal lymphopoietin participates in the TLR2-and TLR4-dependent immune response triggered by Aspergillus fumigatus in human corneal cells

Fungal keratitis constitutes a serious vision-threatening disease. Toll-like receptors (TLRs) comprise key mediators of innate immunity triggered by Aspergillus fumigatus (AF) in the cornea, but the messenger between innate and adaptive immunity remained unknown. Thymic stromal lymphopoietin (TSLP) represents a critical factor of adaptive immunity. Here we investigated the expression of TSLP in corneal epithelial and stromal cells challenged by AF and its relationship with TLRs. We stimulated corneal cells with TLR ligands zymosan or lipopolysaccharide (LPS), human recombinant TSLP, or AF hyphae for various periods, with or without prior TLR2, TLR4, or TSLP inhibition. TLR2, TLR4, TSLP, IL-8, and TNF-α release and expression were measured via enzyme-linked immunosorbent analysis, quantitative polymerase chain reaction, or western blot. Corneal cell stimulation with zymosan or LPS induced up-regulated TSLP expression. Enhanced TSLP expression was associated with AF treatment in human corneal cells; TLR2 or TLR4 inhibition impaired the AF-induced TSLP levels. Human recombinant TSLP augmented TLR2 and TLR4 expression; RNA interference of TSLP attenuated TLR, IL-8, and TNF-α expression stimulated by AF hyphae. These findings indicated that TSLP participates in the immune response of corneal cells triggered by AF, which is closely related to TLR function, and the innate immunity mediated by TLRs could be enhanced by TSLP. Innate immunity may therefore transmit inflammatory signals to adaptive immunity through activation of TSLP; in turn, adaptive immunity likely exerts certain regulatory effects on innate immunity via TSLP. That is, TSLP could interact with innate immunity mediated by TLR2 and TLR4 in human corneal cells challenged by AF and thus may serve as a messenger between the innate and adaptive immune responses in AF keratitis.

Baicalein Protects Against Aspergillus fumigatus Keratitis by Reducing Fungal Load and Inhibiting TSLP-Induced Inflammatory Response

Purpose

To investigate the antifungal and anti-inflammatory effects of baicalein on Aspergillus fumigatus (A. fumigatus) keratitis and the underlying mechanisms.

Methods

The noncytotoxic antifungal concentration of baicalein was determined using CCK8, cell scratch assay, minimum inhibitory concentration, biofilm formation, scanning electron microscopy, propidium iodide uptake test and adherence assay in vitro and Draize test in vivo. In fungal keratitis (FK) mouse models, clinical score and plate count were used to evaluate FK severity, and myeloperoxidase assay and immunofluorescence staining were performed to examine neutrophil infiltration and activity. Real-time PCR, ELISA, and Western blot were performed to explore the anti-inflammatory activity of baicalein and the underlying mechanisms in vivo and in vitro.

Results

Baicalein at 0.25 mM (noncytotoxic) significantly inhibited A. fumigatus growth, biofilm formation, and adhesion in vitro. In A. fumigatus keratitis mice, baicalein mitigated FK severity, reduced fungal load, and inhibited neutrophil infiltration and activity. Baicalein not only suppressed mRNA and protein levels of proinflammatory factors IL-1β, IL-6, and TNF-α, but also inhibited the expression of thymic stromal lymphopoietin (TSLP) and TSLP receptor (TSLPR) in vivo and in vitro. In HCECs, mRNA and protein levels of IL-1β, IL-6, and TNF-α were significantly lower in the TSLP siRNA–treated group, while higher in the rTSLP-treated group than in the corresponding control. Baicalein treatment significantly inhibited rTSLP induced the expression of IL-1β, IL-6, and TNF-α.

Conclusions

Baicalein plays a protective role in mouse A. fumigatus keratitis by inhibiting fungal growth, biofilm formation, and adhesion, and suppressing inflammatory response via downregulation of the TSLP/TSLPR pathway.

TSLP Produced by Aspergillus fumigatus-Stimulated DCs Promotes a Th17 Response Through the JAK/STAT Signaling Pathway in Fungal Keratitis

Purpose

The purpose of this study was to explore the role of thymic stromal lymphopoietin (TSLP) secreted by Aspergillus fumigatus–stimulated dendritic cells (DCs) during the T helper 17 (Th17) immune response, and further clarify the mechanisms contributing to the Th17 immune response of fungal keratitis (FK).

Methods

A carboxyfluorescein diacetate succinimidyl ester assay, PCR, and flow cytometry were performed to detect Th17 differentiation of CD4⁺ T cells; PCR, ELISA, and Western blot were used to detect the expression of TSLP and JAK/STAT–related proteins; Signaling pathways involved in Th17 response was evaluated using RNA sequence; C57BL/6 mice were infected with A. fumigatus and treated with ruxolitinib or BBI608. Slit-lamp examination, fluorescein staining, and clinical scores were used to assess the clinical manifestation.

Results

A. fumigatus–infected DCs could drive naïve CD4⁺ T-cell proliferation and promote the production of Th17 cytokines IL-17A, IL-17F, and IL-22. A. fumigatus stimulation increased the expression of TSLP in DCs. DC-derived TSLP contributed to a Th17-type inflammatory response via the JAK/STAT signaling pathway. TSLP small interfering RNA, TSLPR small interfering RNA, or JAK/STAT inhibitors inhibited the Th17 immune response induced by A. fumigatus–infected DCs. Moreover, TSLP promoted A. fumigatus keratitis disease progression in a mouse model. However, inhibition of the JAK/STAT signaling pathway using a specific inhibitor reversed the development of FK by A. fumigatus infection.

Conclusions

TSLP secreted by A. fumigatus–stimulated DCs played a significant role in the Th17-dominant immune response of FK through its JAK/STAT activation. Our findings may contribute to the elucidation of the molecular mechanisms of FK and to the development of novel therapeutic approaches.

Aspergillus fumigatus-Stimulated Human Corneal Epithelial Cells Induce Pyroptosis of THP-1 Macrophages by Secreting TSLP

Fungal keratitis (FK) is a keratopathy caused by pathogenic fungal infection. The aim of this work is to explore the role of thymic stromal lymphopoietin (TSLP) in FK. Human corneal epithelial cells (HCECs) were treated with Aspergillus fumigatus hyphae, and we found that TSLP was highly expressed and secreted in the hyphae-treated HCECs. Hyphae-treated HCECs or TSLP treatment enhanced the expression of caspase-1 P20, GSDMD-N (p30), IL-1β, and IL-18 in the human THP-1 macrophages. The influence conferred by hyphae-treated HCECs or TSLP treatment was rescued by TSLP neutralizing antibody or VX-765 (caspase-1 inhibitor) treatment. Moreover, TSLP treatment promoted the expression of NLRP3, ASC, caspase-1 P20, GSDMD-N (p30), IL-1β, and IL-18 in the THP-1 macrophages, which was abolished by NLRP3 knockdown. Furthermore, TSLPR silencing suppressed the expression of NLRP3, ASC, caspase-1 P20, GSDMD-N (p30), IL-1β, and IL-18 in the TSLP-treated THP-1 macrophages. In conclusion, our article confirms that Aspergillus fumigatus-stimulated HCECs induce pyroptosis of THP-1 macrophages by secreting TSLP. TSLP/TSLPR induces caspase-1-dependent pyroptosis through activation of NLRP3 inflammasome. Thus, our work suggests that TSLP may be a potential target for FK treatment.

TLR3-Dependent Activation of TLR2 Endogenous Ligands via the MyD88 Signaling Pathway Augments the Innate Immune Response

The role of the adaptor molecule MyD88 is thought to be independent of Toll-like receptor 3 (TLR3) signaling. In this report, we demonstrate a previously unknown role of MyD88 in TLR3 signaling in inducing endogenous ligands of TLR2 to elicit innate immune responses. Of the various TLR ligands examined, the TLR3-specific ligand polyinosinic:polycytidylic acid (poly I:C), significantly induced TNF production and the upregulation of other TLR transcripts, in particular, TLR2. Accordingly, TLR3 stimulation also led to a significant upregulation of endogenous TLR2 ligands mainly, HMGB1 and Hsp60. By contrast, the silencing of TLR3 significantly downregulated MyD88 and TLR2 gene expression and pro-inflammatory IL1β, TNF, and IL8 secretion. The silencing of MyD88 similarly led to the downregulation of TLR2, IL1β, TNF and IL8, thus suggesting MyD88 to somehow act downstream of TLR3. Corroborating in vitro data, Myd88^−/− knockout mice downregulated TNF, CXCL1; and phospho-p65 and phospho-IRF3 nuclear localization, upon poly I:C treatment in a mouse model of skin infection. Taken together, we identified a previously unknown role for MyD88 in the TLR3 signaling pathway, underlying the importance of TLRs and adapter protein interplay in modulating endogenous TLR ligands culminating in pro-inflammatory cytokine regulation.

TSLP Protects Corneas From Pseudomonas aeruginosa Infection by Regulating Dendritic Cells and IL-23-IL-17 Pathway

Purpose

We sought to determine the role of epithelium-produced thymic stromal lymphopoietin (TSLP) and its underlying mechanisms in corneal innate immune defense against Pseudomonas (P.) aeruginosa keratitis.

Methods

The expression of TSLP and TSLPR in cultured human corneal epithelial cells (HCECs) and mouse corneas was determined by PCR, Western, and/or ELISA. Cellular localization of TSLP receptor (TSLPR) was determined by whole mount confocal microscopy. TSLP-TSLPR signaling was downregulated by neutralizing antibodies and/or small interfering (si)RNA; their effects on the severity of P. aeruginosa–keratitis and cytokine expression were assessed using clinical scoring, bacterial counting, PMN infiltration, and real-time PCR. The role of dendritic cells (DCs) in corneal innate immunity was determined by local DC depletion using CD11c-DTR mice.

Results

P. aeruginosa–infection induced the expression of TSLP and TSLPR in both cultured primary HCECs and in C57BL/6 mouse corneas. While TSLP was mostly expressed by epithelial cells, CD11c-positive cells were positive for TSLPR. Targeting TSLP or TSLPR with neutralizing antibodies or TSLPR with siRNA resulted in more severe keratitis, attributable to an increase in bacterial burden and PMN infiltration. TSLPR neutralization significantly suppressed infection-induced TSLP and interleukin (IL)-17C expression and augmented the expression of IL-23 and IL-17A. Local depletion of DCs markedly increased the severity of keratitis and exhibited no effects on TSLP and IL-23 expression while suppressing IL-17A and C expression in P. aeruginosa–infected corneas.

Conclusions

The epithelium-expressed TSLP plays a protective role in P. aeruginosa keratitis through targeting of DCs and in an IL-23/IL-17 signaling pathway-related manner.

Interactions of thymic stromal lymphopoietin with TLR2 and TLR4 regulate anti-fungal innate immunity in Aspergillus fumigatus-induced corneal infection

Thymic stromal lymphopoietin (TSLP) is an interleukin 7 (IL-7)-like four helix bundle cytokine that plays diverse roles in the regulation of immune responses. In fungal infection, pattern recognition receptors (PRRs), including the cell surface Toll-like receptors (TLRs) and cytoplasmic NOD-like receptors, recognize pathogen-associated molecular patterns to initiate downstream signal cascades to active immune responses. Our previous studies reported that, in vitro human cornea epithelium cells represented a novel target of TSLP and that TSLP/TSLPR/STAT5 signaling played an important role in the response to Aspergillus fumigatus challenge. TSLP downstream signaling molecules upregulated TLR2 and MyD88/NF kappa B-p65 signaling. This phenomenon suggested that TSLP had an impact on PRRs in antifungal immunity. In mouse fungal keratitis induced by A. fumigatus, TSLP was mainly expressed in the epithelium as well as in some infiltrated immune cells in a time-dependent manner. Exogenous TSLP with Aspergillus led to severe keratitis and worse corneal recovery with higher levels of TLR2, TLR4, IL-6, and IL-8 as well as increased neutrophil infiltration. By contrast, when TSLP was suppressed by siRNA, fungal keratitis was mild with higher levels of antimicrobial peptides such as human beta-defensin (hBD9). Taken together, our data revealed an unreported function of TSLP in mediating an anti-fungal inflammatory response and serving as a target to control tissue injury and infection in A. fumigatus keratitis.

ATF4 Involvement in TLR4 and LOX-1-Induced Host Inflammatory Response to Aspergillus fumigatus Keratitis

Purpose

Activating transcription factor 4 (ATF4) is induced by various stressors. Here, we investigated the expression of ATF4 in the host inflammatory response to Aspergillus fumigatus (A. fumigatus) keratitis.

Methods

A. fumigatus keratitis mouse models developed by intrastromal injection as well as corneal epithelium scratching were examined daily with a slit lamp microscope for corneal opacification and ulceration. Subsequent in vitro experimentation was carried out in human corneal epithelial cells (HCECs) as well as THP-1 macrophages infected with A. fumigatus. Inhibitors, including CLI-095, Poly (I), SCH772984, and SP600125, were used to assess the role of proteins like toll-like receptor 4 (TLR4), lectin-type oxidized LDL receptor 1 (LOX-1), extracellular signal-regulated kinases (ERK1/2), and c-Jun N-terminal kinase (JNK) in ATF4 expression as a response to A. fumigatus infection. This assessment was made in both mouse models and HCECs using western blot.

Results

Compared to the controls, ATF4 was increased in corneas from two kinds of A. fumigatus keratitis models at 3 days after infection. ATF4 expression was upregulated with A. fumigatus conidia both in HCECs and THP-1 macrophages 16 hours after stimulation. Furthermore, ATF4 expression in response to A. fumigatus infection was shown to be dependent on TLR4 and LOX-1 expression, and ERK1/2 and JNK contributed to the expression of ATF4 in response to A. fumigatus.

Conclusion

Our results clearly indicate that ATF4 was involved in the host antifungal immune response to A. fumigatus keratitis; expression was found to be dependent on TLR4, LOX-1 expression, and MAPKs pathway.

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.

Evaluation of murine lung epithelial cells (TC-1 JHU-1) line to develop Th2-promoting cytokines IL-25/IL-33/TSLP and genes Tlr2/Tlr4 in response to Aspergillus fumigatus

OBJECTIVE

The aims of this study were to determine the role of live and heat-killed Aspergillus fumigatus conidia in releasing interleukin (IL)-25, IL-33 and thymic stromal lymphopoietin (TSLP) and to express Toll-like receptor (Tlr)2 and Tlr4 genes.

MATERIALS AND METHODS

Murine lung epithelial cells were incubated with live and heat-killed A. fumigatus conidia at 37°C for 6, 24 and 48h. After treatments, ELISA was performed to measure the concentrations of IL-25, IL-33 and TSLP in the supernatants. Quantitative real-time PCR (qPCR) was performed to assess the expression levels of Tlr2 and Tlr4 genes.

RESULTS

The concentrations of IL-25 and IL-33 significantly increased after exposure to live and heat-killed conidia for various times when compared with untreated control (P<0.05). The secretion of TSLP at different concentrations of heat-killed conidia was significantly higher than both live conidia and untreated control (P<0.05). qRT-PCR results indicated a up-regulation from 1.08 to 3.60-fold for Tlr2 gene expression and 1.20 to 1.80-fold for Tlr4 gene expression exposed to heat-killed conidia.

CONCLUSION

A. fumigatus has a potential ability to stimulate murine lung epithelial cells to produce IL-25/IL-33/TSLP, as well as to express Tlr2/Tlr4 genes, indicating an important role of lung epithelial cells in innate immune responses to A. fumigatus interaction.