In vivo maturation of T(H) cells in relation to atopy

Multiomics Analysis and Systems Biology Integration Identifies the Roles of IL-9 in Keratinocyte Metabolic Reprogramming

IL-9‒producing T cells are present in healthy skin as well as in the cutaneous lesions of inflammatory diseases and cancers. However, the roles of IL-9 in human skin during homeostasis and in the pathogenesis of inflammatory disorders remain obscure. In this study, we examined the roles of IL-9 in metabolic reprogramming of human primary keratinocytes (KCs). High-throughput quantitative proteomics revealed that IL-9 signaling in human primary KCs disrupts the electron transport chain by downregulating multiple electron transport chain proteins. Nuclear magnetic resonance-based metabolomics showed that IL-9 also reduced the production of tricarboxylic acid cycle intermediates in human primary KCs. An integration of multiomics data with systems-level analysis using the constraint-based MitoCore model predicted marked IL-9-dependent effects on central carbohydrate metabolism, particularly in relation to the glycolytic switch. Stable isotope metabolomics and biochemical assays confirmed increased glucose consumption and redirection of metabolic flux toward lactate by IL-9. Functionally, IL-9 inhibited ROS production by IFN-γ and promoted human primary KC survival by inhibiting apoptosis. In conclusion, our data reveal IL-9 as a master regulator of KC metabolic reprogramming and survival.

Childhood allergy is preceded by an absence of gut lactobacilli species and higher levels of atopy-related plasma chemokines

Alterations in the composition and reduced diversity of the infant microbiome are associated with allergic disease in children. Further, an altered microbiota is linked to immune dysregulation, including skewing of different T helper (Th) subsets, which is also seen in atopic individuals. The aim of this study was, therefore, to investigate the associations between gut lactobacilli and Th‐related plasma factors in allergy development during childhood. A total of 194 children with known allergy status at 1 year of age were followed to 10 years of age. We used real‐time polymerase chain reaction (PCR) to investigate the presence of three lactobacilli species (Lactobacillus casei, L. paracasei, L. rhamnosus) in infant fecal samples (collected between 1 week and 2 months of age) from a subgroup of children. Plasma chemokines and cytokines were quantified at 6 months and at 1, 2, 5 and 10 years of age with Luminex or enzyme‐linked immunosorbent assay (ELISA). Fractional exhaled nitrogen oxide (FeNO) was measured and spirometry performed at 10 years of age. The data were analysed by non‐parametric testing and a logistic regression model adjusted for parental allergy. An absence of these lactobacilli and higher levels of the chemokines BCA‐1/CXCL13, CCL17/TARC, MIP‐3α/CCL20 and MDC/CCL22 in plasma at 6 months of age preceded allergy development. The presence of lactobacilli associated with lower levels of atopy‐related chemokines during infancy, together with higher levels of interferon (IFN)‐γ and lower FeNO during later childhood. The results indicate that the presence of certain lactobacilli species in the infant gut may influence allergy‐related parameters in the peripheral immune system, and thereby contribute to allergy protection.

Low cord blood Foxp3/CD3γ mRNA ratios: a marker of increased risk for allergy development

BACKGROUND

Data from birth cohort studies suggest that increased cord blood total IgE and reduced cord blood regulatory T cells increase the risk of developing allergic sensitization and atopic dermatitis.

OBJECTIVE

We here addressed whether serum total IgE and hen's egg-specific IgE levels at birth and at age 1 year differed between healthy and allergic children in a Belgian birth cohort (FONIA). We furthermore studied whether these parameters as well as cord blood Foxp3/CD3γ mRNA levels might predict the allergic outcome.

METHODS AND RESULTS

Children (n = 84) were clinically assessed at the ages of 6, 12, 18, and 24 months and at 6 years. Cord blood total IgE levels above 0.35 kU/L predicted early (i.e. before or at the age of 2 years) allergy development. Presence of serum IgE antibodies to hen's egg (cut-off 0.05 Ua/mL) at the age of 1 year was associated with early as well as late (i.e. between the age of 2 and 6 years) allergy development. Cord blood Foxp3/CD3γ mRNA ratios were significantly lower in early allergic children and levels below 0.32 predicted the allergic outcome.

CONCLUSIONS AND CLINICAL RELEVANCE

Low cord blood Foxp3/CD3γ mRNA ratios are highly predictive for early allergy development, whereas specific IgE levels to hen's egg white above 0.05 Ua/mL at age 1 year predict allergy development in general.

Expression of interleukin-9 and its upstream stimulating factors in rats with ischemic stroke

To investigate the temporal expressions of IL-9 and its related cytokines after middle cerebral artery occlusion in rats. IL-9 and its related cytokines in ischemia brain and blood were tested after rats were subjected to transient focal ischemia. Comparing with sham-operated group, the levels of IL-4, TGF-β, PU.1, IRF4, OX40, NIK, RelB-p52 and IL-9 in experimental groups were significantly higher after middle cerebral artery occlusion. The results showed that expressions of IL-9 and its upstream stimulating factors increased in experimental stroke, and whether they play a role or just a secondary change is awaiting further research.

Human TH9 cells are skin-tropic and have autocrine and paracrine proinflammatory capacity

T helper type 9 (TH9) cells can mediate tumor immunity and participate in autoimmune and allergic inflammation in mice, but little is known about the TH9 cells that develop in vivo in humans. We isolated T cells from human blood and tissues and found that most memory TH9 cells were skin-tropic or skin-resident. Human TH9 cells coexpressed tumor necrosis factor-α and granzyme B and lacked coproduction of TH1/TH2/TH17 cytokines, and many were specific for Candida albicans. Interleukin-9 (IL-9) production was transient and preceded the up-regulation of other inflammatory cytokines. Blocking studies demonstrated that IL-9 was required for maximal production of interferon-γ, IL-9, IL-13, and IL-17 by skin-tropic T cells. IL-9-producing T cells were increased in the skin lesions of psoriasis, suggesting that these cells may contribute to human inflammatory skin disease. Our results indicate that human TH9 cells are a discrete T cell subset, many are tropic for the skin, and although they may function normally to protect against extracellular pathogens, aberrant activation of these cells may contribute to inflammatory diseases of the skin.

Human Th2 but not Th9 cells release IL-31 in a STAT6/NF-κB-dependent way

IL-31, a member of the IL-6 protein family, is one of the latest additions to the list of T cell-derived cytokines. Th2 cells are regarded as a main source of IL-31, which is produced in response to stimulation by IL-4. Because the development of Th9 cells also requires IL-4 as a polarizing cytokine, the current study investigates IL-31 production in human Th9 cells compared with Th2 cells. We found that, although Th9 cells were able to release IL-31 during the first weeks of in vitro polarization, no IL-31 was detected in Th9 cultures after a final restimulation in the absence of polarizing cytokines. We further show that TGF-β, which is required to obtain Th9 cells in vitro, potently inhibits the release of IL-31 from Th2 cells, whereas IL-33, a cytokine associated with Th2-mediated inflammation, synergizes with IL-4 in inducing IL-31 secretion. To analyze the molecular mechanisms underlying the induction of IL-31, EMSAs, reporter gene assays, and small interfering RNA-based silencing experiments were carried out. We show that STAT6 and NF-κB are central players in mediating IL-31 expression induced by IL-4/IL-33. In addition, we identified a novel NF-κB-binding element within the Il31 promoter that mediates the enhancing effects of IL-33 on IL-4/STAT6-induced IL-31 expression in human Th2 cells. Taken together, this study shows that IL-4 is essential for the production of IL-31, whereas TGF-β significantly suppresses IL-31 expression at the mRNA and protein levels. As a consequence, in vitro polarized Th2 cells, but not Th9 cells, are able to release IL-31.

The symphony of the ninth: the development and function of Th9 cells

CD4+ T helper cells are obligate regulators of inflammatory disease. An expanding cadre of T helper (Th) subsets, specialized for promoting particular types of inflammation, function through the secretion of a restricted set of cytokines. The latest addition to the list of subsets is the Th9 cell that secretes IL-9 as a signature cytokine and contributes to several classes of inflammatory disease. In this review we focus on recent advances in understanding the development of Th9 cells, and how Th9 cells contribute to the orchestration of disease.