Thymic stromal lymphopoietin in normal and pathogenic T cell development and function

Biologic and small-molecule therapy for treating moderate to severe atopic dermatitis: Mechanistic considerations

Atopic dermatitis (AD) is a complex and heterogeneous skin disease for which achieving complete clinical clearance for most patients has proven challenging through single cytokine inhibition. Current studies integrate biomarkers and evaluate their role in AD, aiming to advance our understanding of the diverse molecular profiles implicated. Although traditionally characterized as a TH2-driven disease, extensive research has recently revealed the involvement of TH1, TH17, and TH22 immune pathways as well as the interplay of pivotal immune molecules, such as OX40, OX40 ligand (OX40L), thymic stromal lymphopoietin, and IL-33. This review explores the mechanistic effects of treatments for AD, focusing on mAbs and Janus kinase inhibitors. It describes how these treatments modulate immune pathways and examines their impact on key inflammatory and barrier biomarkers.

CAR-NKT Cells in Asthma: Use of NKT as a Promising Cell for CAR Therapy

NKT cells, unique lymphocytes bridging innate and adaptive immunity, offer significant potential for managing inflammatory disorders like asthma. Activating iNKT induces increasing IFN-γ, TGF-β, IL-2, and IL-10 potentially suppressing allergic asthma. However, their immunomodulatory effects, including granzyme-perforin-mediated cytotoxicity, and expression of TIM-3 and TRAIL warrant careful consideration and targeted approaches. Although CAR-T cell therapy has achieved remarkable success in treating certain cancers, its limitations necessitate exploring alternative approaches. In this context, CAR-NKT cells emerge as a promising approach for overcoming these challenges, potentially achieving safer and more effective immunotherapies. Strategies involve targeting distinct IgE-receptors and their interactions with CAR-NKT cells, potentially disrupting allergen-mast cell/basophil interactions and preventing inflammatory cytokine release. Additionally, targeting immune checkpoints like PDL-2, inducible ICOS, FASL, CTLA-4, and CD137 or dectin-1 for fungal asthma could further modulate immune responses. Furthermore, artificial intelligence and machine learning hold immense promise for revolutionizing NKT cell-based asthma therapy. AI can optimize CAR-NKT cell functionalities, design personalized treatment strategies, and unlock a future of precise and effective care. This review discusses various approaches to enhancing CAR-NKT cell efficacy and longevity, along with the challenges and opportunities they present in the treatment of allergic asthma.

A dual computational and experimental strategy to enhance TSLP antibody affinity for improved asthma treatment

Thymic stromal lymphopoietin is a key cytokine involved in the pathogenesis of asthma and other allergic diseases. Targeting TSLP and its signaling pathways is increasingly recognized as an effective strategy for asthma treatment. This study focused on enhancing the affinity of the T6 antibody, which specifically targets TSLP, by integrating computational and experimental methods. The initial affinity of the T6 antibody for TSLP was lower than the benchmark antibody AMG157. To improve this, we utilized alanine scanning, molecular docking, and computational tools including mCSM-PPI2 and GEO-PPI to identify critical amino acid residues for site-directed mutagenesis. Subsequent mutations and experimental validations resulted in an antibody with significantly enhanced blocking capacity against TSLP. Our findings demonstrate the potential of computer-assisted techniques in expediting antibody affinity maturation, thereby reducing both the time and cost of experiments. The integration of computational methods with experimental approaches holds great promise for the development of targeted therapeutic antibodies for TSLP-related diseases.

Novel chimeric antigen receptor targets and constructs for acute lymphoblastic leukemia: Moving beyond CD19

Acute lymphoblastic leukemia (ALL) is the second most common acute leukemia in adults with a poor prognosis with relapsed or refractory (R/R) B-cell lineage ALL (B-ALL). Anti-CD19 chimeric antigen receptor (CAR) T-cell therapy has shown excellent response rates in RR B-ALL, but most patients relapse due to poor persistence of CAR T-cell therapy or other tumor-associated escape mechanisms. In addition, anti-CD19 CAR T-cell therapy causes several serious side effects such as cytokine release syndrome and neurotoxicity. In this review, we will discuss novel CAR targets, CAR constructs, and various strategies to boost CARs for the treatment of RR B-ALL. In addition, we discuss a few novel strategies developed to reduce the side effects of CAR.

TSLP in DRG neurons causes the development of neuropathic pain through T cells

BACKGROUND

Peripheral nerve injury to dorsal root ganglion (DRG) neurons develops intractable neuropathic pain via induction of neuroinflammation. However, neuropathic pain is rare in the early life of rodents. Here, we aimed to identify a novel therapeutic target for neuropathic pain in adults by comprehensively analyzing the difference of gene expression changes between infant and adult rats after nerve injury.

METHODS

A neuropathic pain model was produced in neonatal and young adult rats by spared nerve injury. Nerve injury-induced gene expression changes in the dorsal root ganglion (DRG) were examined using RNA sequencing. Thymic stromal lymphopoietin (TSLP) and its siRNA were intrathecally injected. T cells were examined using immunofluorescence and were reduced by systemic administration of FTY720.

RESULTS

Differences in changes in the transcriptome in injured DRG between infant and adult rats were most associated with immunological functions. Notably, TSLP was markedly upregulated in DRG neurons in adult rats, but not in infant rats. TSLP caused mechanical allodynia in adult rats, whereas TSLP knockdown suppressed the development of neuropathic pain. TSLP promoted the infiltration of T cells into the injured DRG and organized the expressions of multiple factors that regulate T cells. Accordingly, TSLP caused mechanical allodynia through T cells in the DRG.

CONCLUSION

This study demonstrated that TSLP is causally involved in the development of neuropathic pain through T cell recruitment.

The Role of TSLP in Atopic Dermatitis: From Pathogenetic Molecule to Therapeutical Target

Atopic dermatitis (AD) is a kind of chronic skin disease with inflammatory infiltration, characterized by skin barrier dysfunction, immune response dysregulation, and skin dysbiosis. Thymic stromal lymphopoietin (TSLP) acts as a regulator of immune response, positively associated with AD deterioration. Mainly secreted by keratinocytes, TSLP interacts with multiple immune cells (including dendritic cells, T cells, and mast cells), following induction of Th2-oriented immune response during the pathogenesis of AD. This article primarily focuses on the TSLP biological function, the relationship between TSLP and different cell populations, and the AD treatments targeting TSLP.

Role of pro-inflammatory interleukins in osteoarthritis: a narrative review

PURPOSE

This manuscript will summarize the role of pro-inflammatory cytokines and tackle newly discussed ones within the scope of OA pathogenesis as mentioned in the recent literature. This will allow for a better understanding of the mechanisms behind such a complicated disease.

MATERIAL AND METHODS

Relevant articles were obtained by searching key terms including "pro-inflammatory cytokines," "inflammation," "pathophysiology," "cartilage damage," and "OA" in PubMed and Google Scholar databases. The year ranges set for the selection of the articles was between 2015 -2021. Inclusion criteria was based on the relevance and contribution to the field of the study.

RESULTS

Osteoarthritis (OA) has a complex multifactorial pathophysiology which is attributed to molecular and biomechanical changes that disrupt the normal balance of synthesis and degradation of articular cartilage and subchondral bone. Pro-inflammatory cytokines, with their wide range of action and intricate signaling pathways, are the constant subject of new discoveries revolving around this inflammatory disease. The available literature indicates that some of these cytokines such as IL-33, IL-17, IL-6, and IL-22 have a direct relation to cartilage degradation, while others like IL-15, IL-1, IL-7, and IL-34 have an indirect one.

CONCLUSIONS

Inflammation has an essential role in the manifestation of osteoarthritis clinical events. Specifically, certain cytokines exhibit pro-inflammatory properties that are markedly activated during the course of the disease and notably alter the homeostasis of the joint environment. However, clinical trials and observational studies remain insufficient to navigate the varying nature of this disease in humans.

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.

Early T-Cell Precursor Acute Lymphoblastic Leukemia: Diagnosis, Updates in Molecular Pathogenesis, Management, and Novel Therapies

Early T-cell precursor acute lymphoblastic leukemia (ETP-ALL) is a distinct subtype of T lymphoblastic leukemia (T-ALL) identified in 2009, due to its unique immunophenotypic and genomic profile. The outcome of patients was poor in earlier studies, and they were prone to have induction failure, with more frequent relapse/refractory disease. Recent advances had been made in discoveries of genetic aberrations and molecular pathogenesis of ETP-ALL. However, the diagnosis and management of ETP-ALL is still challenging. There are limited choices of novel therapies so far. In this review article, it highlighted the diagnostic issue of ETP-ALL, pitfall in diagnosis, and strategy of accurate diagnosis. The review also summarized current understanding of molecular mechanism of leukemogenesis. The emerging role of risk-adapted therapy and allogenic stem cell transplant in optimizing the outcome of patients with ETP-ALL was discussed. Finally, some potential novel therapies were proposed based on the current understanding of molecular pathogenesis.

Cellular and molecular mechanisms of allergic asthma

Asthma is a chronic disease of the airways, which affects more than 350 million people worldwide. It is the most common chronic disease in children, affecting at least 30 million children and young adults in Europe. Asthma is a complex, partially heritable disease with a marked heterogeneity. Its development is influenced both by genetic and environmental factors. The most common, as well as the most well characterized subtype of asthma is allergic eosinophilic asthma, which is characterized by a type 2 airway inflammation. The prevalence of asthma has substantially increased in industrialized countries during the last 60 years. The mechanisms underpinning this phenomenon are incompletely understood, however increased exposure to various environmental pollutants probably plays a role. Disease inception is thought to be enabled by a disadvantageous shift in the balance between protective and harmful lifestyle and environmental factors, including exposure to protective commensal microbes versus infection with pathogens, collectively leading to airway epithelial cell damage and disrupted barrier integrity. Epithelial cell-derived cytokines are one of the main drivers of the type 2 immune response against innocuous allergens, ultimately leading to infiltration of lung tissue with type 2 T helper (T_H2) cells, type 2 innate lymphoid cells (ILC2s), M2 macrophages and eosinophils. This review outlines the mechanisms responsible for the orchestration of type 2 inflammation and summarizes the novel findings, including but not limited to dysregulated epithelial barrier integrity, alarmin release and innate lymphoid cell stimulation.

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

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

Deregulation of the Interleukin-7 Signaling Pathway in Lymphoid Malignancies

The cytokine interleukin-7 (IL-7) and its receptor are critical for lymphoid cell development. The loss of IL-7 signaling causes severe combined immunodeficiency, whereas gain-of-function alterations in the pathway contribute to malignant transformation of lymphocytes. Binding of IL-7 to the IL-7 receptor results in the activation of the JAK-STAT, PI3K-AKT and Ras-MAPK pathways, each contributing to survival, cell cycle progression, proliferation and differentiation. Here, we discuss the role of deregulated IL-7 signaling in lymphoid malignancies of B- and T-cell origin. Especially in T-cell leukemia, more specifically in T-cell acute lymphoblastic leukemia and T-cell prolymphocytic leukemia, a high frequency of mutations in components of the IL-7 signaling pathway are found, including alterations in IL7R, IL2RG, JAK1, JAK3, STAT5B, PTPN2, PTPRC and DNM2 genes.

Lymphomagenesis predictors and related pathogenesis

Sjögren's syndrome (SS) is a systemic autoimmune disease characterised by a wide range of clinical manifestations and complications, including B-cell lymphoma. This study aims to describe the predictors associated with lymphomagenesis in patients with Sjögren's syndrome, emphasising the pathophysiological bases that support this association. We performed a review of the literature published through a comprehensive search strategy in PubMed/MEDLINE, Scopus, and Web of science. Forty publications describing a total of 45,208 patients with SS were retrieved. The predictors were grouped according to their pathophysiological role in the lymphoproliferation process. Also, some new biomarkers such as MicroRNAs, P2X7 receptor-NLRP3 inflammasome, Thymic stromal lymphopoietin, and Three-prime repair exonuclease 1 (TREX1) were identified. The knowledge of the pathophysiology allows the discrimination of markers that participate in the initial stages. Considering that the lymphoproliferation process includes the progression of lymphoma towards more aggressive subtypes, it is essential to recognise biomarkers associated with a worse prognosis.

Challenges and Clinical Strategies of CAR T-Cell Therapy for Acute Lymphoblastic Leukemia: Overview and Developments

Chimeric antigen receptor (CAR) T-cell therapy exhibits desirable and robust efficacy in patients with acute lymphoblastic leukemia (ALL). Stimulated by the revolutionized progress in the use of FDA-approved CD19 CAR T cells, novel agents with CAR designs and targets are being produced in pursuit of superior performance. However, on the path from bench to bedside, new challenges emerge. Accessibility is considered the initial barrier to the transformation of this patient-specific product into a commercially available product. To ensure infusion safety, profound comprehension of adverse events and proactive intervention are required. Additionally, resistance and relapse are the most critical and intractable issues in CAR T-cell therapy for ALL, thus precluding its further development. Understanding the limitations through up-to-date insights and characterizing multiple strategies will be critical to leverage CAR T-cell therapy flexibly for use in clinical situations. Herein, we provide an overview of the application of CAR T-cell therapy in ALL, emphasizing the main challenges and potential clinical strategies in an effort to promote a standardized set of treatment paradigms for ALL.

Combretum quadrangulare Extract Attenuates Atopic Dermatitis-Like Skin Lesions through Modulation of MAPK Signaling in BALB/c Mice

Atopic dermatitis (AD) is a chronic inflammatory disease. Combretum quadrangulare (C. quadrangulare) is used as a traditional medicine to improve various pathologies in Southeast Asia. In this study, we investigated the effects of C. quadrangulare ethanol extract (CQ) on 1-chloro-2,4-dinitrobenzene (DNCB)-induced AD like skin lesions in BALB/c mice. After administration with CQ (100, 200, and 400 mg/kg) for 6 weeks, AD symptoms, protein expression, immunoglobulin E (IgE), thymus and activation-regulated chemokine (TARC), and ceramidase level were measured in skin lesions of DNCB-induced BALB/c mice. CQ group improved the dermatitis score, skin pH, transepidermal water loss (TEWL), and skin hydration. Furthermore, histological analysis revealed that CQ attenuated the increased epidermal thickness and infiltration of mast cells caused by DNCB. CQ also increased the expression of filaggrin, and reduced the expression of ceramidase, serum IgE level, and the number of eosinophils. CQ effectively inhibited cytokines and chemokines such as interleukin (IL)-6, IL-13, TARC, and thymic stromal lymphopoietin (TSLP) at the mRNA levels, as well as the activation of mitogen-activated protein kinase (MAPK), including extracellular signal-regulated kinase (ERK), c-jun N-terminal kinase (JNK), and p38 in the skin lesions. Taken together, these findings demonstrate that CQ may be an effective treatment of AD-like skin lesions by inhibiting the expression of inflammatory mediators via the MAPK signaling pathways.

Evolutionary transition from degenerate to nonredundant cytokine signaling networks supporting intrathymic T cell development

In mammals, T cell development critically depends on the IL-7 cytokine signaling pathway. Here we describe the identification of the zebrafish ortholog of mammalian IL-7 based on chromosomal localization, deduced protein sequence, and expression patterns. To examine the biological role of il7 in teleosts, we generated an il7 allele lacking most of its coding exons using CRISPR/Cas9-based mutagenesis. il7-deficient animals are viable and exhibit no obvious signs of immune disorder. With respect to intrathymic T cell development, il7 deficiency is associated with only a mild reduction of thymocyte numbers, contrasting with a more pronounced impairment of T cell development in il7r-deficient fish. Genetic interaction studies between il7 and il7r mutants, and il7 and crlf2(tslpr) mutants suggest the contribution of additional, as-yet unidentified cytokines to intrathymic T cell development. Such activities were also ascertained for other cytokines, such as il2 and il15, collectively indicating that in contrast to the situation in mammals, T cell development in the thymus of teleosts is driven by a degenerate multicomponent network of γc cytokines; this explains why deficiencies of single components have little detrimental effect. In contrast, the dependence on a single cytokine in the mammalian thymus has catastrophic consequences in cases of congenital deficiencies in genes affecting the IL-7 signaling pathway. We speculate that the transition from a degenerate to a nonredundant cytokine network supporting intrathymic T cell development emerged as a consequence of repurposing evolutionarily ancient constitutive cytokine pathways for regulatory functions in the mammalian peripheral immune system.

NKp46-expressing human gut-resident intraepithelial Vδ1 T cell subpopulation exhibits high antitumor activity against colorectal cancer

γδ T cells account for a large fraction of human intestinal intraepithelial lymphocytes (IELs) endowed with potent antitumor activities. However, little is known about their origin, phenotype, and clinical relevance in colorectal cancer (CRC). To determine γδ IEL gut specificity, homing, and functions, γδ T cells were purified from human healthy blood, lymph nodes, liver, skin, and intestine, either disease-free, affected by CRC, or generated from thymic precursors. The constitutive expression of NKp46 specifically identifies a subset of cytotoxic Vδ1 T cells representing the largest fraction of gut-resident IELs. The ontogeny and gut-tropism of NKp46+/Vδ1 IELs depends both on distinctive features of Vδ1 thymic precursors and gut-environmental factors. Either the constitutive presence of NKp46 on tissue-resident Vδ1 intestinal IELs or its induced expression on IL-2/IL-15-activated Vδ1 thymocytes are associated with antitumor functions. Higher frequencies of NKp46+/Vδ1 IELs in tumor-free specimens from CRC patients correlate with a lower risk of developing metastatic III/IV disease stages. Additionally, our in vitro settings reproducing CRC tumor microenvironment inhibited the expansion of NKp46+/Vδ1 cells from activated thymic precursors. These results parallel the very low frequencies of NKp46+/Vδ1 IELs able to infiltrate CRC, thus providing insights to either follow-up cancer progression or to develop adoptive cellular therapies.

The effect of co-occurring lesions on leukaemogenesis and drug response in T-ALL and ETP-ALL

Despite advances in the management of acute lymphoblastic leukaemia (ALL), current regimens fail to significantly transform outcomes for patients with high-risk subtypes. Advances in genomic analyses have identified novel lesions including mutations in genes that encode chromatin modifiers and those that influence cytokine and kinase signalling, rendering many of these alterations potentially targetable by tyrosine kinase and epigenetic inhibitors currently in clinical use. Although specific genomic lesions, gene expression patterns, and immunophenotypic profiles have been associated with specific clinical outcomes in some cancers, the application of precision medicine approaches based on these data has been slow. This approach is complicated by the reality that patients often harbour multiple mutations, and in many cases, the precise functional significance and interaction of these mutations in driving leukaemia and drug responsiveness/resistance remains unknown. Given that signalling pathways driving leukaemic pathogenesis could plausibly result from the co-existence of specific lesions and the resultant perturbation of protein interactions, the use of combined therapeutics that target multiple aberrant pathways, according to an individual’s mutational profile, might improve outcomes and lower a patient’s risk of relapse. Here we outline the genomic alterations that occur in T cell ALL (T-ALL) and early T cell precursor (ETP)-ALL and review studies highlighting the possible effects of co-occurring lesions on leukaemogenesis and drug response.

Short ragweed pollen promotes M2 macrophage polarization via TSLP/TSLPR/OX40L signaling in allergic inflammation

This study was to explore the role and mechanism of macrophages in pollen-triggered allergic inflammation. A murine model of short ragweed (SRW) pollen-induced experimental allergic conjunctivitis (EAC), and bone marrow (BM)-macrophages cultures were used. Typical allergic manifestations and TSLP-stimulated Th2 hyperresponse were observed in ocular surface of EAC model in wild-type (WT) mice induced by SRW. The M2 phenotype markers, Arg1, Ym1 and FIZZ1, were highly expressed by conjunctiva and draining cervical lymph nodes (CLNs) of WT-EAC mice when compared with controls, as evaluated by RT-qPCR and Immunofluorescent double staining with macrophage marker F4/80. The stimulated expression of TSLPR and OX40L by macrophage was detected in conjunctiva and CLNs by RT-qPCR, double staining, and flow cytometry. M2 macrophages were found to produce TARC and MDC. In contrast, EAC model with TSLPR^-/- mice did not show allergic signs and any increase of Th2 cytokines (IL-4, IL-5 and IL-13) and M2 markers. In vitro cultures confirmed that SRW extract stimulates expression of TSLPR, OX40L, TARC, MDC, and three M2 markers by BM-macrophages from WT mice, but not from TSLPR^-/- mice. These findings demonstrate that SRW pollen primes macrophage polarization toward to M2 phenotype via TSLP/TSLPR/OX40L signaling to amplify allergic inflammation.

Korean red ginseng water extract alleviates atopic dermatitis-like inflammatory responses by negative regulation of mitogen-activated protein kinase signaling pathway in vivo

Atopic dermatitis (AD) is a chronic inflammatory skin disease. Korean red ginseng is a Korean traditional medicine. In this study, we estimated the effects of Korean red ginseng water extract (RGE) in the 1-chloro-2,4-dinitrobenzene (DNCB)-induced BALB/c mouse model which develops AD-like lesions. After RGE administration (100, 200, and 400 mg/kg) to DNCB-induced mice there were improvements in the dermatitis score and skin pH, a decrease in trans-epidermal water loss, and improved skin hydration. RGE also significantly inhibited eosinophil infiltration, increased filaggrin protein levels, and decreased serum IgE levels, epidermal thickness, mast cell infiltration, and ceramidase release. Compared with that in DNCB-induced mice, RGE effectively decreased the mRNA expression levels of interleukin-6 (IL-6), thymic stromal lymphopoietin (TSLP), and tumor necrosis factor-α (TNF-α), as well as the protein level of thymus and activation-regulated chemokine (TARC). These inhibitory RGE effects are mediated by inhibiting the phosphorylation of mitogen-activated protein kinases (MAPKs), including extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38 MAPK. Furthermore, we confirmed that RGE suppresses interferon-γ (IFN-γ) and TNF-α-induced expression of macrophage-derived chemokine (MDC) and TARC genes in human keratinocyte (HaCaT) cells. Taken together, these results demonstrate that RGE may exert anti-atopic related to responses by suppression the expression of inflammatory mediators, cytokines, and chemokines via downregulation of MAPK signaling pathways, suggesting that RGE may be an effective therapeutic approach for prevention of AD-like disease.

GBR 830, an anti-OX40, improves skin gene signatures and clinical scores in patients with atopic dermatitis

BACKGROUND

GBR 830 is a humanized mAb against OX40, a costimulatory receptor on activated T cells. OX40 inhibition might have a therapeutic role in T cell-mediated diseases, including atopic dermatitis (AD).

OBJECTIVE

This exploratory phase 2a study investigated the safety, efficacy, and tissue effects of GBR 830 in patients with AD.

METHODS

Patients with moderate-to-severe AD (affected body surface area, ≥10%; Eczema Area and Severity Index score, ≥12; and inadequate response to topical treatments) were randomized 3:1 to 10 mg/kg intravenous GBR 830 or placebo on day 1 (baseline) and day 29. Biopsy specimens were collected (n = 40) at days 1, 29, and 71. Primary end points included treatment-emergent adverse events (TEAEs) and changes from baseline in biomarkers (epidermal hyperplasia/cytokines) at days 29 and 71.

RESULTS

GBR 830 was well tolerated, with equal TEAE distribution (GBR 830, 63.0% [29/46]; placebo, 63.0% [10/16]). One serious TEAE in the GBR 830 group was deemed unrelated to study drug. At day 71, the proportion of intent-to-treat subjects achieving 50% or greater improvement in Eczema Area and Severity Index score was greater with GBR 830 (76.9% [20/26]) versus placebo (37.5% [3/8]). GBR 830 induced significant progressive reductions in T_H1 (IFN-γ/CXCL10), T_H2 (IL-31/CCL11/CCL17), and T_H17/T_H22 (IL-23p19/IL-8/S100A12) mRNA expression in lesional skin. Significant progressive reductions until day 71 in the drug group were seen in OX40⁺ T cells and OX40L⁺ dendritic cells (P < .001). Hyperplasia measures (thickness/keratin 16/Ki67) showed greater reductions with GBR 830 (P < .001).

CONCLUSIONS

Two doses of GBR 830 administered 4 weeks apart were well tolerated and induced significant progressive tissue and clinical changes until day 71 (42 days after the last dose), highlighting the potential of OX40 targeting in patients with AD.

MicroRNAs: Mediators and Therapeutic Targets to Airway Hyper Reactivity After Respiratory Syncytial Virus Infection

Respiratory syncytial virus (RSV) is the most important pathogen correlated to the first-time infant wheezing and later recurrence after its primary infection. RSV infection promotes the bronchial smooth muscle sensitivity to leukotrienes (LTs) in acute stage, causes the extensive inflammatory reaction and the aggregation of Th2-like cells during respiratory tract obstruction. Infants and young children infected with RSV exhibit an increased susceptibility to the exposure of exogenous allergens, easy to suffer from the recurrent wheezing, which prompts that the body is still in a state of inflammation or immunological bias. However, the pathological mechanism is unclear. The recent researches demonstrate that abnormal expression of non-coding microRNAs (miRNAs) can be detected from the peripheral blood and airway tract epithelial of RSV infected infants, which participate the regulation of immune cells polarization and LTs synthesis. Improving the immune tolerance can significantly relieve the airway inflammation and broncho-spasm caused by RSV. In this review, we discuss recent advances in understanding the mechanism of RSV-induced inflammatory reaction and immune dysfunction leading to airway hyper-reactivity. Further, we summarize the potential molecular basis that, in this process, miRNAs, which are produced by airway epithelial cells or peripheral blood mononuclear cells, directly or in the form of exosome to regulate the inflammation programs as well as the function, differentiation and proliferation of immune cells. miRNAs may become a potential bio-marker of detecting severe RSV infection and a novel target of early intervention and therapeutic strategy in recurrent wheezing or asthma related to RSV infection.

Genetic Regulation of the Thymic Stromal Lymphopoietin (TSLP)/TSLP Receptor (TSLPR) Gene Expression and Influence of Epistatic Interactions Between IL-33 and the TSLP/TSLPR Axis on Risk of Coronary Artery Disease

The thymic stromal lymphopoietin (TSLP)/TSLP receptor (TSLPR) axis is involved in multiple inflammatory immune diseases, including coronary artery disease (CAD). To explore the causal relationship between this axis and CAD, we performed a three-stage case-control association analysis with 3,628 CAD cases and 3,776 controls using common variants in the genes TSLP, interleukin 7 receptor (IL7R), and TSLPR. Three common variants in the TSLP/TSLPR axis were significantly associated with CAD in a Chinese Han population [rs3806933^T in TSLP, P_adj = 4.35 × 10^-5, odds ratio (OR) = 1.18; rs6897932^T in IL7R, P_adj = 1.13 × 10^-7, OR = 1.31; g.19646A>G^A in TSLPR, P_adj = 2.04 × 10^-6, OR = 1.20]. Reporter gene analysis demonstrated that rs3806933 and rs6897932 could influence TSLP and IL7R expression, respectively. Furthermore, the "T" allele of rs3806933 might increase plasma TSLP levels (R² = 0.175, P < 0.01). In a stepwise procedure, the risk for CAD increased by nearly fivefold compared with the maximum effect of any single variant (P_adj = 6.99 × 10^-4, OR = 4.85). In addition, the epistatic interaction between TSLP and IL33 produced a nearly threefold increase in the risk of CAD in the combined model of rs3806933^TT-rs7025417^TT (P_adj = 3.67 × 10^-4, OR = 2.98). Our study illustrates that the TSLP/TSLPR axis might be involved in the pathogenesis of CAD through upregulation of mRNA or protein expression of the referenced genes and might have additive effects on the CAD risk when combined with IL-33 signaling.

Effects of microRNA-19b on airway remodeling, airway inflammation and degree of oxidative stress by targeting TSLP through the Stat3 signaling pathway in a mouse model of asthma

This study explored the effects of microRNA-19b (miR-19b) on airway remodeling, airway inflammation, and degree of oxidative stress in a mouse model of asthma. Bioinformatics analyses and dual luciferase reporter gene assays revealed that thymic stromal lymphopoietin (TSLP) is a direct target of miR-19b. An asthma model was established via ovalbumin (OVA) sensitization and challenge in 72 female BALB/c mice. Mice were then assigned to saline, OVA-sensitized, saline+miR-19b mimics, saline+anti-TSLP, OVA-sensitized+miR-19b mimics, OVA-sensitized+mimics scramble, OVA-sensitized+anti-TSLP, and OVA-sensitized+IgG2a groups. Pathological morphology changes were detected through hematoxylin/eosin, Masson, and periodic acid-Schiff staining. miR-19b was downregulated while TSLP and Stat3 were upregulated in the OVA-sensitized group compared with the saline group. Bronchoalveolar lavage fluid samples from OVA-sensitized mice showed increased total protein, IL-4, IL-5 and IL-6 levels, numbers of inflammatory cells, eosinophils, neutrophils, mononuclear macrophages and lymphocytes, and eosinophil% compared to controls. Lung tissues from sensitized mice exhibited decreased superoxide dismutase activity and increased methane dicarboxylic aldehyde levels. The effects of OVA sensitization were reversed in the OVA-sensitized+miR-19b mimics and OVA-sensitized+anti-TSLP groups. These findings suggest miR-19b reduces airway remodeling, airway inflammation, and degree of oxidative stress by inhibiting Stat3 signaling through TSLP downregulation in a mouse asthma model.

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.

Hypoxia and Local Inflammation in Pulmonary Artery Structure and Function

Hypoxia is recognized as a contributor to pulmonary vascular diseases such as pulmonary hypertension. Hypoxia-induced inflammatory changes can enhance structural and functional changes in pulmonary artery (PA) in the context of PH. Accordingly, understanding how hypoxia and inflammation are linked in the context of pulmonary artery structure and function could be relevant towards development of novel therapies for PH. In this regard, factors such as thymic stromal lymphopoietin (TSLP), an inflammatory cytokine, and brain-derived neurotrophic factor (BDNF), a neurotrophin, have been found critical for nonvascular systems such as airway and asthma. While TSLP canonically affects the immune system, in nonvascular systems, noncanonical effects such as altered [Ca²⁺]_i and cell proliferation have been noted: aspects also relevant to the PA, where there is currently little to no data. Similarly, better known in the nervous system, there is increasing evidence that BDNF is locally produced by structural cells of the airway and can contribute to asthma pathophysiology. In this chapter, we summarize the potential relevance of factors such as TSLP and BDNF to the PA and in the context of hypoxia influences towards development of PH. We focus on cell sources and targets such as PA endothelial cells (PAECs) and smooth muscle cells (PASMCs), and the effects of TSLP or BDNF on intracellular Ca²⁺ responses to vasoconstrictor agonist, cell proliferation, and potential signaling cascades involved.

Application of a phenotypic drug discovery strategy to identify biological and chemical starting points for inhibition of TSLP production in lung epithelial cells

Thymic stromal lymphopoietin (TSLP) is a cytokine released by human lung epithelium in response to external insult. Considered as a master switch in T helper 2 lymphocyte (Th2) mediated responses, TSLP is believed to play a key role in allergic diseases including asthma. The aim of this study was to use a phenotypic approach to identify new biological and chemical starting points for inhibition of TSLP production in human bronchial epithelial cells (NHBE), with the objective of reducing Th2-mediated airway inflammation. To this end, a phenotypic screen was performed using poly I:C / IL-4 stimulated NHBE cells interrogated with a 44,974 compound library. As a result, 85 hits which downregulated TSLP protein and mRNA levels were identified and a representative subset of 7 hits was selected for further characterization. These molecules inhibited the activity of several members of the MAPK, PI3K and tyrosine kinase families and some of them have been reported as modulators of cellular phenotypic endpoints like cell-cell contacts, microtubule polymerization and caspase activation. Characterization of the biological profile of the hits suggested that mTOR could be a key activity involved in the regulation of TSLP production in NHBE cells. Among other targeted kinases, inhibition of p38 MAPK and JAK kinases showed different degrees of correlation with TSLP downregulation, while Syk kinase did not seem to be related. Overall, inhibition of TSLP production by the selected hits, rather than resulting from inhibition of single isolated targets, appeared to be due to a combination of activities with different levels of relevance. Finally, a hit expansion exercise yielded additional active compounds that could be amenable to further optimization, providing an opportunity to dissociate TSLP inhibition from other non-desired activities. This study illustrates the potential of phenotypic drug discovery to complement target based approaches by providing new chemistry and biology leads.

Oxidative stress and cellular pathways of asthma and inflammation: Therapeutic strategies and pharmacological targets

Asthma is a complex inflammatory disease characterized by airway inflammation and hyperresponsiveness. The mechanisms associated with the development and progression of asthma have been widely studied in multiple populations and animal models, and these have revealed involvement of various cell types and activation of intracellular signaling pathways that result in activation of inflammatory genes. Significant contributions of Toll-like-receptors (TLRs) and transcription factors such as NF-кB, have been reported as major contributors to inflammatory pathways. These have also recently been associated with mechanisms of oxidative biology. This is of important clinical significance as the observed inefficacy of current available treatments for severe asthma is widely attributed to oxidative stress. Therefore, targeting oxidizing molecules in conjunction with inflammatory mediators and transcription factors may present a novel therapeutic strategy for asthma. In this review, we summarize TLRs and NF-кB pathways in the context of exacerbation of asthma pathogenesis and oxidative biology, and we discuss the potential use of polyphenolic flavonoid compounds, known to target these pathways and possess antioxidant activity, as potential therapeutic agents for asthma.

Novel concepts of prevention and treatment of atopic dermatitis through barrier and immune manipulations with implications for the atopic march

Skin barrier abnormalities have been suggested to play an essential role in initiation of early atopic dermatitis (AD). Antigen penetration through a compromised barrier likely leads to increased innate immune responses, antigen-presenting cell stimulation, and priming of overt cutaneous disease. In a T_H2-promoting environment, T-cell/B-cell interactions occurring in regional lymph nodes lead to excessive IgE switch. Concurrent redistribution of memory T cells into the circulation not only leads to exacerbation of AD through T-cell skin infiltration but also spreads beyond the skin to initiate the atopic march, which includes food allergy, asthma, and allergic rhinitis. Possible primary interventions to prevent AD are focusing on improving skin barrier integrity, including supplementing barrier function with moisturizers. As for secondary prophylaxis in children with established AD, this can be stratified into prevention of disease exacerbations by using proactive approaches (with either topical corticosteroids or topical calcineurin inhibitors) in mild AD cases or the prevention of other atopic disorders that will probably mandate systemic immunosuppression in severe AD cases.

The immunology of atopic dermatitis and its reversibility with broad-spectrum and targeted therapies

Atopic dermatitis (AD), the most common chronic inflammatory skin disease, is driven by both terminal keratinocyte differentiation defects and strong type 2 immune responses. In contrast to chronic plaque-type psoriasis, AD is now understood to be a much more heterogeneous disease, with additional activation of T_H22, T_H17/IL-23, and T_H1 cytokine pathways depending on the subtype of the disease. In this review we discuss our current understanding of the AD immune map in both patients with early-onset and those with chronic disease. Clinical studies with broad and targeted therapeutics have helped to elucidate the contribution of various immune axes to the disease phenotype. Importantly, immune activation extends well beyond lesional AD because nonlesional skin and the blood component harbor AD-specific inflammatory changes. For this reason, future therapeutics will need to focus on a systemic treatment approach, especially in patients with moderate-to-severe disease.

Critical role of TSLP-responsive mucosal dendritic cells in the induction of nasal antigen-specific IgA response

Thymic stromal lymphopoietin (TSLP) is an interleukin-7 (IL-7)-like cytokine involved in T helper 2 type immune responses. The primary target of TSLP is myeloid dendritic cells (DCs), however, little is known about the mechanism by which TSLP elicits respiratory IgA immune responses upon mucosal immunization. Here, we found that the levels of TSLP and TSLPR were upregulated in the mucosal DCs of mice nasally immunized with pneumococcal surface protein A (PspA) plus cholera toxin (CT) compared with those immunized with PspA alone. PspA-specific IgA responses, but not IgG Ab responses were significantly reduced in both serum and mucosal secretions of TSLPR knockout mice compared with wild-type mice after nasal immunization with PspA plus CT. Furthermore, CD11c⁺ mucosal DCs isolated from TSLPR knockout mice nasally immunized with PspA plus CT were less activated and exhibited markedly reduced expression of IgA-enhancing cytokines (e.g., APRIL, BAFF, and IL-6) compared with those from equivalently immunized wild-type mice. Finally, exogenous TSLP promoted production of IgAs in an in vitro DC-B cell co-culture system as exhibited by enhanced IL-6 production. These results suggest that TSLP-TSLPR signaling is pivotal in the induction of nasal respiratory immunity against pathogenic pneumococcal infection.

Identification of High-risk Cryptic CRLF2 Rearrangements in B-Cell Acute Lymphoblastic Leukemia Utilizing an FGFR3/IGH Dual-Color Dual-Fusion DNA Probe Set

B-cell acute lymphoblastic leukemia (B-ALL) is the most common childhood malignancy with gene rearrangements involving the IGH locus occurring in ∼5% of cases. Fluorescence in situ hybridization (FISH) probes targeting the IGH locus are not included in the standard children's oncology group (COG) fluorescence in situ hybridization panel. At our institute, we incorporated the use of FGFR3/IGH dual-color dual-fusion DNA probes for confirmation of aneuploidy 4 and 14 in diagnostic B-ALL specimens. Subsequently we have identified 4 B-ALL cases with cryptic CRLF2-IGH translocations that would otherwise have gone undetected. Detection of genetic alterations in B-ALL, such as CRLF2 rearrangements, may enhance patient risk stratification and therapy options in pediatric B-ALL.

TSLP is a direct trigger for T cell migration in filaggrin-deficient skin equivalents

Mutations in the gene encoding for filaggrin (FLG) are major predisposing factors for atopic dermatitis (AD). Besides genetic predisposition, immunological dysregulations considerably contribute to its pathophysiology. For example, thymic stromal lymphopoietin (TSLP) is highly expressed in lesional atopic skin and significantly contributes to the pathogenesis of AD by activating dendritic cells that then initiate downstream effects on, for example, T cells. However, little is known about the direct interplay between TSLP, filaggrin-deficient skin and other immune cells such as T lymphocytes. In the present study, FLG knockdown skin equivalents, characterised by intrinsically high TSLP levels, were exposed to activated CD4⁺ T cells. T cell exposure resulted in an inflammatory phenotype of the skin equivalents. Furthermore, a distinct shift from a Th1/Th17 to a Th2/Th22 profile was observed following exposure of T cells to filaggrin-deficient skin equivalents. Interestingly, TSLP directly stimulated T cell migration exclusively in filaggrin-deficient skin equivalents even in the absence of dendritic cells, indicating a hitherto unknown role of TSLP in the pathogenesis of AD.

Acetylcholine polarizes dendritic cells toward a Th2-promoting profile

BACKGROUND

A growing body of research shows a reciprocal regulation between the neural and immune systems. Acetylcholine (ACh) is the most important parasympathetic neurotransmitter, and increasing evidence indicates that it is able to modulate the immune response. Interestingly, in recent years, it has become clear that immune cells express a non-neuronal cholinergic system, which is stimulated in the course of inflammatory processes. We have previously shown that dendritic cells (DC) express muscarinic receptors, as well as the enzymes responsible for the synthesis and degradation of ACh. Here, we analyzed whether ACh could also modulate the functional profile of DC.

METHODS

Dendritic cells were obtained from monocytes cultured for 5 days with GM-CSF+IL-4 or isolated from peripheral blood (CD1c+ DC). The phenotype of DC was evaluated by flow cytometry, the production of cytokines was analyzed by ELISA or intracellular staining and flow cytometry, and the expression of muscarinic and nicotinic receptors was evaluated by flow cytometry or qRT-PCR.

RESULTS

Treatment of DC with ACh stimulated the expression of the Th2-promoter OX40L, the production of the Th2-chemokines MDC (macrophage-derived chemokine/CCL22) and TARC (thymus and activation-regulated chemokine/CCL17), and the synthesis of IL-4, IL-5, and IL-13 by T cells, in the course of the mixed lymphocyte reaction (MLR). Moreover, we found that the stimulation of OX40L, HLA-DR, and CD83 expressions in DC induced by the Th2-promoting cytokine TSLP, as well as the production of IL-13, IL-4, and IL-5 by T cells in the course of the MLR, was further enhanced when DC were treated with TSLP plus ACh, instead of TSLP or ACh alone.

CONCLUSIONS

Our observations suggest that ACh polarizes DC toward a Th2-promoting profile.

Th2 Cells and Th17 Cells in the Development of Endometriosis – Possible Roles of Interleukin-4 and Interleukin-17A

Endometriosis is recognized as an inflammatory disease in which inflammatory cytokines, such as interleukin (IL)-1β and TNFα, play important roles. Immunological factors are also suggested to be involved in the pathogenesis of endometriosis. This review provides comprehensive knowledge about helper T cell (Th cell) and its specific cytokines in endometriosis. A series of our studies demonstrated the presence of Th2 cells and Th17 cells in endometriotic tissues and revealed multiple effects of IL-4 and IL-17A, cytokines secreted from respective Th cells. IL-1β induces secretion of thymic stromal lymphopoietin (TSLP), a regulator for differentiation of inflammatory Th2 cells, in endometriotic stromal cells (ESCs). IL-4 stimulates proliferation of ESCs and production of 3β-hydroxysteroid dehydrogenase Type 2, an enzyme in an estrogen production pathway, in ESCs. IL-17A stimulates IL-8 and Gro-α secretion from ESCs and proliferation of ESCs. IL-17A-induced Gro-α promotes neutrophil migration, which may contribute to the presence of neutrophils in endometriotic tissues. IL-17A also increases secretion of CCL20, a chemokine for Th17 cells, from ESCs, which seems to induce migration of Th17 cells to the endometriotic tissues and enhance the effects of IL-17A further. TNFα in combination with IL-17A synergistically enhances secretion of IL-8 and CCL-20, suggesting cooperation of inflammation and Th17 immune response. These findings suggest that IL-4 and IL-17A promote the development of endometriosis through induction of cell proliferation, inflammation, and estrogen production. It is thus also suggested that IL-4 and IL-17A would be a target of treatment of the disease.

Thymic stromal lymphopoietin in tonsillar follicular dendritic cells correlates with elevated serum immunoglobulin A titer by promoting tonsillar immunoglobulin A class switching in immunoglobulin A nephropathy

Immunoglobulin A (IgA) nephropathy (IgAN) is characterized by high serum IgA levels and IgA deposition in the renal mesangium. Previous studies suggest that elevated serum IgA partly originates from the tonsils. Here, we investigated the mechanisms of IgA production in the tonsils of patients with IgAN. Immunohistochemistry revealed that the number and relative percentage of IgA-bearing cells were significantly increased in the tonsils of IgAN patients. Compared with non-IgAN patients, enhanced IgA class switching and overexpression of thymic stromal lymphopoietin (TSLP), TSLP receptor (TSLPR), activation-induced cytidine deaminase (AID), transforming growth factor-β1 (TGF-β1), B cell-activating factor of the tumor necrosis factor family (BAFF), and a proliferation-inducing ligand (APRIL) were detected in follicular dendritic cells (FDCs) of tonsillar germinal centers from IgAN patients. Importantly, TSLP correlated with IgA production in isolated FDC-associated clusters. Serum TSLP levels were increased and correlated with IgA overexpression in the tonsils and serum of IgAN patients. These data indicated that TSLP overexpression in tonsillar FDCs may promote IgA class switching in IgAN patients through the cooperative roles of AID, TGF-β1, BAFF, and APRIL. Therefore, interactions between TSLP in FDCs and IgA production in tonsils may be an important mechanism contributing to the pathogenesis of IgAN.

Insight into the role of TSLP in inflammatory bowel diseases

Proinflammatory cytokines are thought to modulate pathogeneses of various inflammatory bowel diseases (IBDs). Thymic stromal lymphopoietin (TSLP), which has been studied in various allergic diseases such as asthma, atopic dermatitis (AD) and eosinophilic esophagitis (EoE), has been less considered to be involved in IBDs. However, mucosal dendritic cells (DCs) induced by various cytokines including TSLP were reported to cause polarization of T cell toward Th2 response, the differentiation of regulatory T-cell (Treg), and secretion of IgA by B cells. In this review, we discuss the concept that decreased TSLP has the potential to accelerate the development of Th1 response dominant diseases such as the Crohn's disease (CD) while increased TSLP has the potential to lead to a development of Th2 cell dominant diseases such the ulcerative colitis (UC). To examine TSLP's role as a potential determining factor for differentiating UC and CD, we analyzed the effects of other genes regulated by TSLP in regards to the UC and CD pathogeneses using data from online open access resources such as NetPath, GeneMania, and the String database. Our findings indicate that TSLP is a key mediator in the pathogenesis of IBDs and that further studies are needed to evaluate its role.

Thymic Stromal Chemokine TSLP Acts through Th2 Cytokine Production to Induce Cutaneous T-cell Lymphoma

Thymic stromal lymphopoietin (TSLP) activates dendritic cells to induce Th2-mediated inflammation. Periostin, an extracellular matrix protein produced by fibroblasts, induces chronic inflammation by stimulating TSLP production. Recently, a reinforcing cycle linking Th2-type immune responses with periostin-induced keratinocyte activation has been proposed in atopic dermatitis pathogenesis. In this study, we investigated the role of TSLP and periostin in the development of cutaneous T-cell lymphoma (CTCL), where Th2 cytokines and chemokines are also dominant. TSLP and periostin mRNA expression levels were elevated in CTCL lesional skin, both of which correlated with IL4 expression levels. In vitro and ex vivo, IL4 or IL13 stimulated periostin expression by dermal fibroblasts, and fibroblasts from CTCL lesional skin expressed higher levels of periostin than those from control skin. Serum periostin levels of CTCL patients were also significantly higher than those of healthy individuals. Hut78 and MJ, CTCL cell lines, and peripheral blood mononuclear cells from leukemic CTCL patients expressed the TSLP receptor. TSLP induced production of IL4 and IL13 by Hut78 and MJ cells through the activation of STAT5. Moreover, TSLP induced proliferation of CTCL cells both in vitro and in vivo These data suggest that periostin-mediated TSLP production by keratinocytes directly stimulates CTCL tumor cell growth in addition to inducing a Th2-dominant tumor environment in CTCL. Cancer Res; 76(21); 6241-52. ©2016 AACR.

Ligand-receptor dissociated expression explains high TSLP without prognostic impact in human primary head and neck squamous cell carcinoma

Thymic stromal lymphopoietin (TSLP) is an interleukin (IL)-7-like cytokine expressed by epithelial cells during allergic inflammation, and activating dendritic cells (DC). Its expression and functional role in cancer remain controversial. We conducted retrospective (n = 89), and prospective studies including patients with untreated primary head and neck squamous cell carcinoma (HNSCC). We found that TSLP was overexpressed by HNSCC tumor cells, and associated with a highly differentiated status. However, no significant difference in overall and recurrence-free survival was found between patients bearing a tumor with high and low TSLP levels, respectively. Surprisingly, there was no significant association between the levels of TSLP expression, and the number of tumor-infiltrating mature DCLAMP(+) DC. In order to explain the apparent lack of TSLP-induced DC activation, we performed phenotypic and functional experiments on freshly resected tumors. Tumor-infiltrating immune cells, including DC, did not express the TSLP receptor heterodimer (TSLPR chain, IL-7Ralpha chain). Furthermore, freshly sorted blood CD11c(+) DC from healthy donors cultured with tumor-conditioned supernatant exhibited an activated profile, but this was not affected by an anti-TSLP blocking antibody, suggesting a DC activation pathway independent of tumor-derived TSLP. Overall, our results demonstrate that TSLP is overexpressed in HNSCC but its function is hampered by the lack of TSLPR-expressing cells in the tumor microenvironment. Such a dissociated ligand-receptor expression may impact intercellular communication in other immune activation pathways, and tumor types.

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

Our previous studies reported that pattern recognition receptors (PRRs), including the cell surface Toll-like receptors (TLRs) and cytoplasmic NOD-like receptors (NLRs), recognize pathogen-associated molecular patterns (PAMPS) to initiate downstream signal cascades to active immunity responses. Thymic stromal lymphopoietin (TSLP) has recently emerged as a key cytokine in the development of type 2 adaptive immune responses. However, the crosstalk between PRRs and TSLP has not been well elucidated in Aspergillus fumigates keratitis. Our studies demonstrated that HCECs not only respond to TSLP, but also initiate immunological regulation through TSLP/TSLPR/STAT5 signaling pathway. In addition, we revealed that zymosan TLR2 agonist enhanced the expression of TSLP and TSLPR and phosphorylation of STAT5. Furthermore, neutralization of TLR2 with monoclonal Ab prevented the production of TSLP and TSLPR and phosphorylation of STAT5 from increasing which induced by A. fumigatus hyphae. Interestingly, we also found that human recombinant TSLP induced the increase of TLR2 downstream signal molecules, and TSLP knockdown could reduce the increase of TLR2 downstream signaling molecules(MyD88 and NF-κB-p65) induced by A. fumigatus hyphae. These studies indicated that HCECs represent a novel target of TSLP, TSLP/TSLPR/STAT5 signaling plays an important role in response to A. fumigatus infection in HCECs, and TLR2 downstream signaling molecules up regulate TSLP/TSLPR/STAT5 signaling as well as TSLP downstream signaling molecules up regulate TLR2/MyD88/NFκB-p65 signaling in this phenomenon.

TSLP expression in the skin is mediated via RARγ-RXR pathways

TSLP is an important trigger and initiator for various atopic diseases mainly atopic dermatitis (AD). Activators of nuclear hormone receptors like bioactive vitamin A and D derivatives are known to induce TSLP up-regulation in the skin. In this study, various combinations of synthetic specific agonists and antagonists of the retinoic acid receptors (RARs), retinoid X receptors (RXRs) and vitamin D receptor (VDR) were topically administered to mice. The aim of the study was to elucidate via which nuclear hormone receptor pathways TSLP is regulated and how this regulation is connected to the development and phenotype of atopic dermatitis. TSLP expression was monitored using QRT-PCR and serum TSLP levels using ELISA. Synthetic agonists of the VDR and RARγ as well as the natural agonist all-trans retinoic acid (ATRA) increased TSLP expression in the skin, while an RXR agonist was not active. Treatments with antagonists of RXRs and RARs in addition to RARα-agonists reduced skin TSLP expression. Strong activation was found after a combination of a VDR and an RXR agonist (ca. 5 times induction) and even stronger by an RARγ and an RXR agonist treatment (ca. 48 times induction). We conclude that besides VDR-mediated signaling mainly RARγ-RXR mediated pathways in the skin are important patho-physiological triggers for increased skin TSLP expression. We conclude that topical synthesized retinoids stimulated by internal or external triggers or topically applied induce TSLP production and are thereby important triggers for atopic dermatitis prevalence.