TSLP polymorphisms, allergen exposures, and the risk of atopic disorders in children

Association between bronchial asthma and TSLP gene polymorphism: a systematic review and meta-analysis

Aims

This study entails an association between bronchial asthma and common single nucleotide polymorphisms (SNPs) in thymic stromal lymphopoietin (TSLP) gene; rs2289278, rs3806933, rs2289276, and rs1837253.

Methods

The databases of PubMed, Embase, Web of Science, and Google Scholar were searched for studies reporting TSLP polymorphisms and asthma from inception to January 2022. Hardy-Weinberg equilibriums (HWE) for each polymorphism of the control group were checked using the χ 2 test. The association was estimated by means of odds ratio (OR) with 95% CI in both dominant and recessive modes of inheritance, respectively.

Results

Altogether, 11 studies with 3121 asthma cases and 3041 healthy controls were added. Results from six studies showed that the SNP rs2289278 had a protective role in asthma development (OR=0.65, 95% CI: 0.44-0.97, P=0.04). Pooling of four studies showed that the SNP rs3806933 had higher odds of developing asthma (OR=1.32, 95% CI:1.14-1.54, P<0.01). However, the SNP rs2289276 and rs1837253 showed no significant association. From the subgroup analysis, SNPs rs2289278 and rs1837253 were protective against the development of asthma in Asia. However, SNP rs2289276 showed a risk association in Asia and in adults.

Conclusion

This meta-analysis shows that the SNP rs2289278 has a protective effect on the development of asthma; whereas rs3806933 has a risk of asthma. Additionally, this study adds genomic-based support to the recent FDA approval of tezepelumab, an anti-TSLP agent.

Nuts, vegetables, fruits, and protein dietary pattern during pregnancy is inversely associated with risk of childhood allergies: a case-control study

Allergic diseases are prevalent chronic conditions among children and can lead to significant health and economic issues. It is hypothesized that healthy and high quality diet during pregnancy can prevent the onset of allergic diseases in offspring. This study aimed to investigate the potential relationship between major dietary patterns during pregnancy and allergies in children under one year of age. This case-control study was conducted involving 244 participants (122 mothers of allergic children and 122 healthy controls) who visited pediatricians and allergy outpatient clinics in Khuzestan Province, Iran, between June 2022 and March 2023. Demographic information was recorded using a socio-demographic questionnaire. A food frequency questionnaire was used to identify the foods consumed during pregnancy. Major dietary patterns were extracted using principal component analysis, and the potential relationship between these patterns and childhood allergies was investigated using multivariable logistic regression models. The crude odds ratio (OR) analysis showed that the fourth quartile of "Nut, vegetables, fruits, and protein" dietary pattern was associated with lower occurrence of childhood allergies (OR: 0.214, 95% CI = 0.068-0.679; P trend = 0.211). After adjusting for cofactors in Model 3, this association was still observed in the fourth quartile (OR = 0.108, 95% CI = 0.019-0.613; P trend, 0.001). However, no significant association was observed between "Carbohydrate and cereals" and "Salty" dietary patterns and childhood allergies. The study findings suggest that a maternal dietary pattern rich in nuts, vegetables, and fruits during pregnancy may reduce the risk of allergic diseases in offspring.

Thymic Stromal Lymphopoietin (TSLP), Its Isoforms and the Interplay with the Epithelium in Allergy and Asthma

Thymic stromal lymphopoietin (TSLP) is a pleiotropic cytokine that has emerged as a critical player in the development and progression of allergy and asthma. It is primarily produced by epithelial cells and functions as a potent immune system activator. TSLP acts through interaction with its receptor complex, composed of the TSLP receptor (TSLPR) and interleukin-7 receptor alpha chain (IL-7Rα), activating downstream complex signalling pathways. The TSLP major isoform, known as long-form TSLP (lfTSLP), is upregulated in the airway epithelium of patients with allergic diseases. More research is warranted to explore the precise mechanisms by which short-form TSLP (sfTSLP) regulates immune responses. Understanding the dynamic interplay between TSLP and the dysfunctional epithelium provides insights into the mechanisms underlying allergy and asthma pathogenesis. Targeting TSLP represents an important therapeutic strategy, as it may upstream disrupt the inflammatory cascade and alleviate symptoms associated with allergic inflammation.

Role of thymic stromal lymphopoietin in allergy and beyond

Thymic stromal lymphopoietin (TSLP) is a pleiotropic cytokine that acts on multiple cell lineages, including dendritic cells, T cells, B cells, neutrophils, mast cells, eosinophils and innate lymphoid cells, affecting their maturation, survival and recruitment. It is best known for its role in promoting type 2 immune responses such as in allergic diseases and, in 2021, a monoclonal antibody targeting TSLP was approved for the treatment of severe asthma. However, it is now clear that TSLP has many other important roles in a variety of settings. Indeed, several genetic variants for TSLP are linked to disease severity, and chromosomal alterations in TSLP are common in certain cancers, indicating important roles of TSLP in disease. In this Review, we discuss recent advances in TSLP biology, highlighting how it regulates the tissue environment not only in allergic disease but also in infectious diseases, inflammatory diseases and cancer. Encouragingly, therapies targeting the TSLP pathway are being actively pursued for several diseases.

Break on through: The role of innate immunity and barrier defence in atopic dermatitis and psoriasis

The human skin can be affected by a multitude of diseases including inflammatory conditions such as atopic dermatitis and psoriasis. Here, we describe how skin barrier integrity and immunity become dysregulated during these two most common inflammatory skin conditions. We summarise recent advances made in the field of the skin innate immune system and its interaction with adaptive immunity. We review gene variants associated with atopic dermatitis and psoriasis that affect innate immune mechanisms and skin barrier integrity. Finally, we discuss how current and future therapies may affect innate immune responses and skin barrier integrity in a generalized or more targeted approach in order to ameliorate disease in patients.

Genetic variants affecting chemical mediated skin immunotoxicity

The skin is an immune-competent organ and this function may be impaired by exposure to chemicals, which may ultimately result in immune-mediated dermal disorders. Interindividual variability to chemical-induced skin immune reactions is associated with intrinsic individual characteristics and their genomes. In the last 30-40 years, several genes influencing susceptibility to skin immune reactions were identified. The aim of this review is to provide information regarding common genetic variations affecting skin immunotoxicity. The polymorphisms selected for this review are related to xenobiotic-metabolizing enzymes (CYPA1 and CYPB1 genes), antioxidant defense (GSTM1, GSTT1, and GSTP1 genes), aryl hydrocarbon receptor signaling pathway (AHR and ARNT genes), skin barrier function transepidermal water loss (FLG, CASP14, and SPINK5 genes), inflammation (TNF, IL10, IL6, IL18, IL31, and TSLP genes), major histocompatibility complex (MHC) and neuroendocrine system peptides (CALCA, TRPV1, ACE genes). These genes present variants associated with skin immune responses and diseases, as well as variants associated with protecting skin immune homeostasis following chemical exposure. The molecular and association studies focusing on these genetic variants may elucidate their functional consequences and contribution in the susceptibility to skin immunotoxicity. Providing information on how genetic variations affect the skin immune system may reduce uncertainties in estimating chemical hazards/risks for human health in the future.

TSLP disease-associated genetic variants combined with airway TSLP expression influence asthma risk

BACKGROUND

Thymic stromal lymphopoietin (TSLP) is an epithelial-derived cytokine important in initiation of allergic inflammation. Single nucleotide polymorphisms (SNPs) in TSLP are associated with asthma, yet studies have shown inconsistent associations between circulating TSLP and asthma. Studies that integrate the combined effects of TSLP genotype, TSLP mRNA, circulating TSLP levels, and asthma outcome are lacking.

OBJECTIVES

This study sought to recruit a novel cohort based on asthma-relevant TSLP SNPs and determine their impact on TSLP mRNA expression and TSLP circulating protein levels, and their individual and combined effects on asthma.

METHODS

This study developed an algorithm to prioritize TSLP SNPs and recruited 51 carriers and noncarriers based on TSLP genotypes. TSLP mRNA was quantified in nasal epithelial cells and circulating TSLP levels in plasma. This study determined the associations of defined TSLP risk genotypes and/or TSLP mRNA and protein levels with asthma.

RESULTS

TSLP mRNA expression, but not circulating TSLP, was significantly increased in people who are asthmatic compared with in people who are nonasthmatic (P = .007; odds ratio, 1.44). Notably, 90% of children with the defined TSLP risk genotypes and high nasal TSLP mRNA expression (top tertile) had asthma compared with 40% of subjects without risk genotypes and with low TSLP expression (bottom tertile) (P = .024). No association between circulating TSLP and asthma was observed.

CONCLUSIONS

Collectively, these data suggest childhood asthma is modified by the combined effects of TSLP genotype and TSLP expression in the nasal epithelium. The increased asthma risk likely manifests when genetic variation enables expression quantitative trait loci in the TSLP locus to elevate TSLP. It is important to consider both biomarkers when factoring asthma risk.

TSLP as druggable target - a silver-lining for atopic diseases?

Atopic diseases refer to common allergic inflammatory diseases such as atopic dermatitis (AD), allergic rhinitis (AR), and allergic asthma (AA). AD often develops in early childhood and may herald the onset of other allergic disorders such as food allergy (FA), AR, and AA. This progression of the disease is also known as the atopic march, and it goes hand in hand with a significantly impaired quality of life as well as a significant economic burden. Atopic diseases usually are considered as T helper type 2 (Th2) cell-mediated inflammatory diseases. Thymic stromal lymphopoietin (TSLP), an epithelium-derived pro-inflammatory cytokine, activates distinct immune and non-immune cells. It has been shown to be a master regulator of type 2 immune responses and atopic diseases. In experimental settings, the inhibition or knockout of TSLP signaling has shown great therapeutic potential. This, in conjunction with the increasing knowledge about the central role of TSLP in the pathogenesis of atopic diseases, has sparked an interest in TSLP as a druggable target. In this review, we will discuss the autocrine and paracrine effects of TSLP, how it regulates the tissue microenvironment and drives atopic diseases, which provide the rationale for the increasing interest in TSLP as a druggable target.

Histoire naturelle de la dermatite atopique

Atopic dermatitis (AD) is a common frequent chronic inflammatory skin disease which begins frequently in infancy. The clinical expression of AD is a recurrent eczema on a dry skin. AD is a multifactorial disease characterized by two linked abnormalities: a skin barrier defect and a cellular inflammation, with type-2 main components. However, the pathophysiology of AD is not as simple as this description looks like. In this review, we will present a synthesis of current knowledge on natural history of AD and the involved factors, in order to clarify AD care. The evolution of AD is associated with many atopic comorbidities, following the "atopic march" scheme: IgE-mediated food allergy, allergic asthma and rhinitis occurring classically after AD. In fact, this is rarely the case, but the atopic march seems to be associated with AD severity. AD has also many neuropsychological complications which are essential to be detected. Other factors could influence the natural history of AD: genetic mutations on different genes (proteins of skin barrier, innate and adaptive immunity pathways), skin dysbiosis with colonization by Staphylococcus aureus, sensitization against environmental proteins. AD treatment is based on the restauration of the skin barrier using emollients and on anti-inflammatory drugs (notably topical corticosteroids) during the inflammatory flares. It is not recommended to treat the skin colonization by S. aureus, excepted in case of skin infection. The probiotics have no efficiency as curative treatment of AD, but could have an interest for the primary prevention, especially in at-risk populations. © 2019 Elsevier Masson SAS. All rights reserved.

How does parental history of atopic disease predict the risk of atopic dermatitis in a child? A systematic review and meta-analysis

BACKGROUND

Parental history of atopic disease is a well-established risk factor for the development of atopic dermatitis (AD), but several aspects of this association remain unclear.

OBJECTIVE

We sought to determine the association of parental history of atopic disease with AD in offspring.

METHODS

We searched PubMed and EMBASE through June 2018 for relevant records and adhered to the Preferred Reporting Items for Systematic Reviews and Meta-Analyses guidelines. Pooled odds ratios (ORs) with 95% CI were calculated using random-effects models.

RESULTS

A total of 163 records covering 149 unique studies were included. Of these, 119 studies were included in the meta-analysis. Individuals with parental history of atopic disease had increased odds of AD (OR, 1.81; 95% CI, 1.65-1.99). Parental asthma (OR, 1.56; 95% CI, 1.18-2.05) and allergic rhinitis (OR, 1.68; 95% CI, 1.34-2.11) had a smaller effect than AD (OR, 3.30; 95% CI, 2.46-4.42). The effect of maternal and paternal history was comparable for all atopic diseases. An increase in odds was observed when comparing the effect of having 1 (OR, 1.30; 95% CI, 1.15-1.47) or 2 atopic parents (OR, 2.08; 95% CI, 1.83-2.36), as well as having a parent with 1 (OR, 1.49; 95% CI, 1.28-1.74) or more atopic diseases (OR, 2.32; 95% CI, 1.92-2.81).

CONCLUSIONS

This study provides evidence-based risk estimates that may guide physicians who counsel parents with a history of atopic disease about their children's risk of AD. This information is of particular importance for future efforts toward establishing prophylactic interventions for AD on a general population level.

New and Potential Treatments for Atopic Dermatitis: Biologicals and Small Molecules

PURPOSE OF REVIEW

An update on new therapies currently approved or potentially useful in the future for the management of patients suffering moderate-to-severe atopic dermatitis.

RECENT FINDINGS

New pathogenic mechanisms involved in atopic dermatitis have permitted to propose novel therapeutic approaches devised to control the inflammatory process observed in involved cutaneous tissues by neutralizing mediators, cytokines, and their receptors. Recent research findings have disclosed important and previously unrecognized pathogenic mechanisms that have resulted in innovative targeted therapies, such as dupilumab, and potentially other biologicals and small molecules. Further studies should permit the sub-classification of patients according to the relevance of different mediators and inflammatory cells. It can be concluded that the treatment of atopic dermatitis has entered into the era of personalized/precision medicine.

New Cytokines in the Pathogenesis of Atopic Dermatitis-New Therapeutic Targets

Atopic dermatitis (AD) is a recurrent, chronic, and inflammatory skin disease, which processes with severe itchiness. It often coexists with different atopic diseases. The number of people suffering from AD is relatively high. Epidemiological research demonstrates that 15–30% of children and 2–10% adults suffer from AD. The disease has significant negative social and economic impacts, substantially decreasing the quality of life of the patients and their families. Thanks to enormous progress in science and technology, it becomes possible to recognise complex genetic, immunological, and environmental factors and epidermal barrier defects that play a role in the pathogenesis of AD. We hope that the new insight on cytokines in AD will lead to new, individualised therapy and will open different therapeutic possibilities. In this article, we will focus on the cytokines, interleukin (IL)-17, IL-19, IL-33, and TSLP (thymic stromal lymphopoietin), which play a significant role in AD pathogenesis and may become the targets for future biologic therapies in AD. It is believed that the new era of biological drugs in AD will give a chance for patients to receive more successful treatment.

Thymic Stromal Lymphopoietin Isoforms, Inflammatory Disorders, and Cancer

Thymic stromal lymphopoietin (TSLP) is a pleiotropic cytokine originally isolated from a murine thymic stromal cell line. TSLP exerts its biological effects by binding to a high-affinity heteromeric complex composed of thymic stromal lymphopoietin receptor chain and IL-7Rα. TSLP is primarily expressed by activated lung and intestinal epithelial cells, keratinocytes, and fibroblasts. However, dendritic cells (DCs), mast cells, and presumably other immune cells can also produce TSLP. Different groups of investigators have demonstrated the existence of two variants for TSLP in human tissues: the main isoform expressed in steady state is the short form (sf TSLP), which plays a homeostatic role, whereas the long form (lfTSLP) is upregulated in inflammatory conditions. In addition, there is evidence that in pathological conditions, TSLP can be cleaved by several endogenous proteases. Several cellular targets for TSLP have been identified, including immune (DCs, ILC2, T and B cells, NKT and Treg cells, eosinophils, neutrophils, basophils, monocytes, mast cells, and macrophages) and non-immune cells (platelets and sensory neurons). TSLP has been originally implicated in a variety of allergic diseases (e.g., atopic dermatitis, bronchial asthma, eosinophilic esophagitis). Emerging evidence indicates that TSLP is also involved in chronic inflammatory (i.e., chronic obstructive pulmonary disease and celiac disease) and autoimmune (e.g., psoriasis, rheumatoid arthritis) disorders and several cancers. These emerging observations greatly widen the role of TSLP in different human diseases. Most of these studies have not used tools to analyze the expression of the two TSLP isoforms. The broad pathophysiologic profile of TSLP has motivated therapeutic targeting of this cytokine. Tezepelumab is a first-in-class human monoclonal antibody (1) that binds to TSLP inhibiting its interaction with TSLP receptor complex. Tezepelumab given as an add-on-therapy to patients with severe uncontrolled asthma has shown safety and efficacy. Several clinical trials are evaluating the safety and the efficacy of tezepelumab in different inflammatory disorders. Monoclonal antibodies used to neutralize TSLP should not interact or hamper the homeostatic effects of sf TSLP.

TIPE2 Inhibits the Expression of Asthma-Related Inflammatory Factors in Hyperstretched Bronchial Epithelial Cells Through the Wnt/β-Catenin Pathway

Childhood asthma, an airway inflammatory disease, is a serious threat to the child's quality of life. Recently, TIPE2 expression was reported to be decreased in children with asthma. Therefore, additional studies focusing on TIPE2 might provide an approach for treating childhood asthma. In this study, we found that TIPE2 was poorly expressed in hyperstretched human bronchial epithelial cells (BEAS-2B). TIPE2 overexpression also significantly suppressed the stretch-induced secretion of asthma-related inflammatory factors (TNF-α, TSLP, MMP-9, and VEGF). In contrast, TIPE2 inhibition significantly promoted the secretion of TNF-α, TSLP, MMP-9, and VEGF. Furthermore, overexpression of TIPE2 remarkably inhibited the activation of Wnt/β-catenin in hyperstretched BEAS-2B cells, while siTIPE2 activated Wnt/β-catenin in hyperstretched BEAS-2B cells. Further analysis showed that the Wnt/β-catenin signal inhibitor Dkk-1 could further enhance the TIPE2-induced suppression of Wnt/β-catenin signaling, which also suppressed the siTIPE2-induced secretion of TNF-α, TSLP, MMP-9, and VEGF in hyperstretched BEAS-2B cells. Dkk-1 reversed the effects of siRNA-TIPE2 on Wnt/β-catenin signaling and inflammatory cytokines. In summary, we have exhibited that TIPE2 inhibited the expression of asthma-related inflammatory factors in hyperstretched BEAS-2B cells by suppressing the Wnt/β-catenin signaling pathway. TIPE2 may be involved in airway inflammation during asthma attack, and it may be used as a potential therapeutic target for bronchial epithelial inflammation in childhood asthma.

Increased expression of thymic stromal lymphopoietin in induced sputum from asthmatic children

OBJECTIVE

Thymic stromal lymphopoietin (TSLP) plays a role in amplifying the inflammatory response in asthmatics. TSLP is also a critical factor in airway remodeling airways. The aim of this study was to assess the expression of TSLP in induced sputum from asthmatic children and to look to the impact of TNF-α and IL-37 on TSLP production in induced sputum from asthmatic children.

METHODS

Forty children with well-controlled asthma (20 moderate and 20 mild asthmatics) were studied. TSLP was measured by enzyme-linked immunosorbent assay (ELISA) in induced sputum (IS) samples, and compared with 22 age- and sex-matched healthy controls. Real-time quantitative PCR was used to determine TSLP mRNA expression in induced sputum cells. Sputum cells (ISCs) from 5 moderate asthmatics and 5 healthy controls (HC) were stimulated either with TNF-α or TNF-α plus recombinant IL-37 (rIL-37) comparing the suppression on TSLP production.

RESULTS

The expression of TSLP mRNA in asthmatic patients was significantly higher than that observed in healthy controls [P=0.0001]. Induced sputum fluid TSLP and TNF-α levels were significantly higher in asthmatic patients compared to healthy controls and their levels depend on asthma severity. Sputum cells produced high TSLP levels upon stimulation with TNF-α (10pg/ml) in asthmatics. TSLP is merely produced by bronchial epithelial cells. Addition of recombinant IL-37 suppressed partially TSLP production in sputum-cultured cells and in bronchial epithelial cultured cells.

CONCLUSIONS

The increase in TSLP and TNF-α level observed in IS fluid was found to correlate with disease severity. The increased TSLP production from asthma sputum cells was abrogated by the addition of rIL-37. Regulation of TSLP pathway may be a therapeutic approach for asthma.