Th9: a new player in asthma pathogenesis?

IL-9 neutralizing antibody suppresses allergic inflammation in ovalbumin-induced allergic rhinitis mouse model

Allergic rhinitis is mainly mediated by IgE after specific individuals are exposed to allergens. It is a common nasal mucosa disease of non-infectious chronic inflammatory disease and is often accompanied by asthma and conjunctivitis. In the study of allergic asthma, it was found that IL-9 participates in the pathogenic development of asthma. Because asthma and allergic rhinitis have the same airway and the same disease, it is inferred that IL-9 may also play an important role in allergic rhinitis. BALB/c mice received intranasal stimulation of ovalbumin (OVA) treatment at different times. The nasal mucosa of the mice were then sliced and stained with Sirius red and Toluidine blue, and eosinophils and mast cells in the mucosa were counted. ELISA was used to detect the expression of OVA-IgE in peripheral blood. The Th2 cell fraction in the mouse spleen was detected by flow cytometry. The expressions of IL-4, IL-5, IL-9, and IL-13 and their mRNA in mucosa were detected by real-time PCR and flow cytometry bead array analysis. Finally, the expression changes of Thymic stromal lymphopoietin related proteins and its mRNA, JAK1/2, and STAT5 proteins were detected by real-time PCR and Western blot. After the intervention with the IL-9 neutralizing antibody, the symptoms of allergic rhinitis in mice were significantly reduced. The expression of OVA-IgE in the peripheral blood of mice was inhibited, the fraction of Th2 cells in the spleen decreased, the related cytokines (IL-4, IL-5, and IL-13) were inhibited, and their functions decreased. The TSLP-OX40/OX40L signal pathway and JAK1/2-STAT5 signal are inhibited. IL-9 neutralizing antibody has a good therapeutic effect on the mouse model of allergic rhinitis, which may be related to the TSLP-OX40/OX40L pathway and JAK1/2-STAT5 signaling.

Gulf Asthma Diagnosis and Management in Adults: Expert Review and Recommendations

The prevalence and incidence of asthma are increasing globally because of genetic and environmental influences. Prevalence of asthma in the Gulf has been reported to range from 4.7% to 32.0% and has a substantial economic burden. In this paper, we summarize current asthma management guidance for adults, present insights, and recommendations by key opinion leaders (KOLs) in the Gulf region, and key performance indicators for guiding clinical practice for asthma diagnosis, management, and treatment in the Gulf. While it is recommended that the Global Initiative for Asthma (GINA) guidelines should be followed wherever possible for the management of asthma, KOLs in the Gulf region have presented additional recommendations based on regional challenges and insights. There is a need for better diagnosis using objective testing, increased efforts in tackling the burden of comorbidities in the region, and greater provision of the necessary tools for phenotyping severe asthma. Furthermore, there is a need for greater education for physicians regarding asthma treatment, including the importance of inhaled-corticosteroid-containing controller medication. Regionally, there is also a need for specialist asthma clinics and asthma educators, which would serve to educate physicians and their patients as well as to improve the management of patients. Finally, the use of asthma registries, digital devices, and electronic templates would be of benefit in the management of asthma patients in the region.

IL-27 overexpression alleviates inflammatory response in allergic asthma by inhibiting Th9 differentiation and regulating Th1/Th2 balance

OBJECTIVE

To investigate the effect of IL-27 on Th9 differentiation and Th1/Th2 balance.

METHODS

C57BL/6 (B6) mice were treated with ovalbumin to establish an allergic asthma (AA) model and subjected to IL-27 overexpression (OV) and empty vector (EV). Hematoxylin-eosin (HE) staining was performed to observe lung tissue inflammation. Flow cytometry was carried out to evaluate the percentage of Th9, Th1, and Th2 cells. The expression of IL-27, IL-27R, IL-9, T-bet, IFN-γ, and IgE was evaluated by quantitative reverse transcription polymerase chain reaction (qRT-PCR) and enzyme-linked immunosorbent assay (ELISA). Western blot was conducted to observe the expression of pSTAT-1 and pSTAT-3.

RESULTS

Compared with the Model group, the number of Th1 cells in the Model + OV group increased significantly (p < .05), while those of Th9 and Th2 cells decreased significantly (p < .05). The expression of IL-27, IL-27R, and IFN-γ in blood serum was increased (p < .05), and that of IL-9 and IgE was significantly decreased in the Model + OV group compared to the Model (p < .05). Western blot revealed that Model + OV exhibited lower expression of pSTAT-3 than that in the Model and Model + EV groups (p < .05), while pSTAT-1 expression was significantly increased (p < .05). Inflammatory infiltration in the Model + OV group was significantly reduced, and there was no significant difference between the Model and Model + EV groups.

CONCLUSIONS

IL-27 OV inhibits Th9 differentiation and regulates the imbalance of Th1/Th2, thereby alleviating inflammatory response in AA. The findings suggest that IL-27 OV may be a potential strategy for clinical treatment of AA.

Blimp-1 inhibits Th9 cell differentiation and attenuates diabetic coronary heart disease

Diabetic coronary heart disease (DM-CHD) poses a major threat to the world. The newly described T cell subset-Th9 cells and related cytokine interleukin (IL)-9 play important roles in the pathogenesis of diabetes and atherosclerosis. B lymphocyte-induced maturation protein 1 (Blimp-1) has been indicated to negatively regulate Th9 development in allergic asthma, but its role in DM-CHD remains unclear. Hence, this study was designed to investigate the role of Blimp-1 in DM-CHD and to elucidate whether the mechanism was associated with regulation of Th9 cell differentiation. Our results showed that serum Blimp-1 mRNA level was decreased whereas proportion of Th9 cells (IL-9+ CD4+ T cells) and serum level of Th9-related IL-9 were increased in DM-CHD patients. Furthermore, serum Blimp-1 mRNA level was negatively correlated with IL-9 level in DM-CHD patients. Importantly, administration of lentiviruses expressing Blimp-1 (LV-Blimp-1) significantly inhibited Th9 cell differentiation and alleviated the severity of atherosclerotic lesions in the aorta and coronary artery, dyslipidemia, inflammation, vascular endothelial dysfunction, and oxidative stress in DM-CHD model rats. Collectively, Blimp-1 exerts a protective effect in DM-CHD rats and the mechanism might involve inhibition of Th9 cell differentiation.

SGK1 enhances Th9 cell differentiation and airway inflammation through NF-κB signaling pathway in asthma

This study aimed to explore the effect of Sgk1 on Th9 differentiation and the underlying mechanism in asthma. The asthmatic mouse model induced by ovalbumin (OVA) and CD4⁺T cells which were cultured with TGF-β, IL-2, IL-4, and anti-IFN-γ were applied in vivo and in vitro, respectively. Flow cytometry, quantitative real-time PCR (qRT-PCR), and ELISA were performed to detect T-helper 9 (Th9) cells, IL-9 expression, and IL-9 release. Western blot was performed to examine phosphorylated(p)-IKKα, p-IκBα, p-p65, and IRF4 levels. Hematoxylin/eosin (H&E) staining was adopted to assess pathological changes of lung tissues. Inhibition of Sgk1 dramatically reversed elevated Th9 cells and IL-9 expression in the lung tissues of asthmatic mice. In vitro, Sgk1 promoted Th9 differentiation and elevated p-IKKα, p-IκBα, p-p65, and IRF4 levels, but inhibition of IKKα/IκBα/p65 pathway and IRF4 both reversed enhanced Th9 differentiation by Sgk1. Sgk1→IKKα/IκBα/NF-κBp65→IRF4→Th9 axis may be implicated in asthma development.

Involvement of T-Helper 9 Activation in a Mouse Model of Allergic Rhinitis

Background

We aimed to investigate the role of T-Helper (TH) 9 cells in the pathogenesis of allergic rhinitis (AR) in mice.

Material/Methods

An AR model was produced in BALB/c mice, and the viral encoding interleukin (IL)-9 silencing sequence was used to reduce IL-9 expression. The experiment was divided into a control group, an AR group, an IL-9 shRNA+AR group, and a vector+AR group. Hematoxylin and eosin (H&E) staining was used to detect pathological changes. The cytokine expression was detected by ELISA method. Cellular typing was detected by flow cytometry.

Results

Cells in the control group were regularly arranged, with clear layers and no congestion, edema, or necrosis observable. By contrast, in the AR model group and the vector treatment group, nasal mucosa showed clear hyperemia and edema in upper tissues and infiltration of inflammatory cells, which were ameliorated by IL-9 silencing. Compared with the control group, interferon-γ (IFN-γ) was significantly down-regulated, while IL-4, IL-17, and IL-9 were significantly elevated in the AR model group. TH1 cells in nasal mucosa, lymph, nasal lavage, spleen, and peripheral blood were significantly reduced, while TH2, TH9, TH17, and Treg cells were significantly elevated in the AR group compared with the control group. Importantly, all these changes in AR model were ameliorated by IL-9 silencing.

Conclusions

AR is related to the changes of cytokines in TH1, TH2, TH9, TH17, and Treg, which are improved by IL-9 silencing. Activation of TH9 cells is involved in the pathogenesis of AR.

IL-9: Function, Sources, and Detection

IL-9 is a pleiotropic cytokine produced in different amounts by a wide variety of cells including mast cells, NKT cells, Th2, Th17, Treg, ILC2, and Th9 cells. Th9 cells are considered to be the main CD4+ T cells that produce IL-9. IL-9 exerts its effects on multiple types of cells and different tissues. To date, its main role has been found in the immune responses against parasites and pathogenesis of allergic diseases such as asthma and bronchial hyperreactivity. Additionally, it induces the proliferation of hematologic neoplasias, including Hodgkin's lymphoma in humans. However, IL-9 also has antitumor properties in solid tumors such as melanoma. The objective of this review is to describe IL-9, its function, sources, and methods of detection.

Synovial IL-9 facilitates neutrophil survival, function and differentiation of Th17 cells in rheumatoid arthritis

Background

Role of Th9 cells and interleukin-9 (IL-9) in human autoimmune diseases such as psoriasis and ulcerative colitis has been explored only very recently. However, their involvement in human rheumatoid arthritis (RA) is not conclusive. Pathogenesis of RA is complex and involves various T cell subsets and neutrophils. Here, we aimed at understanding the impact of IL-9 on infiltrating immune cells and their eventual role in synovial inflammation in RA.

Methods

In vitro stimulation of T cells was performed by engagement of anti-CD3 and anti-CD28 monoclonal antibodies. Flow cytometry was employed for measuring intracellular cytokine, RORγt in T cells, evaluating apoptosis of neutrophils. ELISA was used for measuring soluble cytokine, Western blot analysis and confocal microscopy were used for STAT3 phosphorylation and nuclear translocation.

Results

We demonstrated synovial enrichment of Th9 cells and their positive correlation with disease activity (DAS28-ESR) in RA. Synovial IL-9 prolonged the survival of neutrophils, increased their matrix metalloprotienase-9 production and facilitated Th17 cell differentiation evidenced by induction of transcription factor RORγt and STAT3 phosphorylation. IL-9 also augmented the function of IFN-γ + and TNF-α + synovial T cells.

Conclusions

We provide evidences for critical role of IL-9 in disease pathogenesis and propose that targeting IL-9 may be an effective strategy to ameliorate synovial inflammation in RA. Inhibiting IL-9 may have wider impact on the production of pathogenic cytokines involved in autoimmune diseases including RA and may offer better control over the disease.

Electronic supplementary material

The online version of this article (10.1186/s13075-017-1505-8) contains supplementary material, which is available to authorized users.

Relationship of circulating chemerin and omentin levels with Th17 and Th9 cell immune responses in patients with asthma

OBJECTIVE

Adipokines are correlated with immune responses in asthma, but data on the roles of chemerin and omentin in asthma are limited. This study explored the relationship of chemerin and omentin levels with Th17 and Th9 cells in asthma.

METHODS

Seventy-six asthmatics were divided into intermittent-to-mild persistent (n  =  28), moderate persistent (n  =  26) and severe persistent (n  =  22) and were enrolled in the study. Additionally, 20 healthy subjects were enrolled as controls. Clinical characteristics of the subjects, the Asthma Control Test, lung function, fractional exhaled nitric oxide score, and plasma chemerin and omentin levels were evaluated, and the percentages of Th17 and Th9 cells were determined by flow cytometry.

RESULTS

The percentages of Th17 and Th9 cells were higher in the moderate-to-severe persistent asthmatics than in the intermittent-to-mild persistent asthmatics or healthy controls (p < 0.05). The severe persistent asthma group had a higher chemerin level but lower omentin levels than the control group (p < 0.05). Chemerin levels were positively correlated with Th17 and Th9 cell percentages, while omentin levels were negatively correlated with Th17 and Th9 cell percentages (p < 0.01).

CONCLUSIONS

The regulatory functions of adipokines on immune responses may be associated with pathogenesis and processes of asthma.

Anti-IgE and Biologic Approaches for the Treatment of Asthma

Current asthma treatments are effective for the majority of patients with mild-to-moderate disease. However, in those with more severe refractory asthma, agents other than inhaled corticosteroids and beta-agonists are needed both to better manage this group of patients and to avoid the side effects of high-dose corticosteroids and the social and personal hardship endured. Several biological pathways have been targeted over the last 20 years, and this research has resulted in pharmacological approaches to attempt to better treat patients with severe refractory asthma. The flagship of the biologics, the anti-IgE monoclonal antibody, omalizumab, has proven efficacious in selected subgroups of asthma patients. Tailoring asthma treatments to suit specific subtypes of asthma patients is in keeping with ideals of personalized medicine. Research in the complex interplay of allergens, epithelial host defenses, cytokines, and innate and adaptive immunity interactions has allowed better understanding of the mechanics of allergy and inflammation in asthma. As a result, new biologic treatments have been developed that target several different phenotypes and endotypes in asthma. As knowledge of the efficacy of these biological agents in asthma emerges, as well as the type of patients in whom they are most beneficial, the movement toward personalized asthma treatment will follow.

Expression levels of transcription factor PU.1 and interleukin-9 in atopic dermatitis and their relation to disease severity and eruption types

BACKGROUND

The role of immunological factors in atopic dermatitis (AD) pathogenesis is well established. T-helper (TH) cells are central in AD pathogenesis. A relatively new subset of T cells, Th9 cells, was shown to be involved in the development of allergic asthma and allergic rhinitis, while its role in AD is still to be investigated. This study aimed to measure gene expression levels of interleukin-9 (IL-9) and PU.1, and to examine relationships with disease severity, serum IgE, and eruption types in AD patients.

METHODS

The study enrolled 30 AD patients, 30 psoriasis patients, and 30 healthy subjects. The severity of AD was assessed using the SCORAD index. IL-9 and PU.1 expressions were measured by using real-time quantitative polymerase chain reaction (RQ-PCR). Serum IgE was measured by IgE (human) enzyme-linked immunosorbent assay (ELISA) Kit.

RESULTS

IL-9 and PU.1 gene expressions were significantly higher in AD patients than in controls (P1 = 0.007, P2 < 0.001, respectively). In the atopic dermatitis patients, expression of IL-9 and PU.1 were significantly positively correlated with SCORAD index (P1 = 0.004, P2 = 0.002) and clinically with erythema and edema scores. IL-9 and PU.1 expressions were positively significantly correlated (P = 0.005) and positively correlated with serum IgE in the AD group (P1 = 0.017, P2 = 0.023). No significant difference was noted between AD patients with or without histories of other atopies regarding expression levels of IL-9 and PU.1 (P1 = 0.677, P2 = 0.135).

CONCLUSIONS

PU.1 and IL-9 may play a role in AD pathogenesis and relate to disease severity and clinical eruption types.

Dectin-1 Plays an Important Role in House Dust Mite-Induced Allergic Airway Inflammation through the Activation of CD11b+ Dendritic Cells

It is well known that sensitization against fungi is closely associated with severity of asthma. Dectin-1 (gene symbol Clec7a), a C-type lectin receptor, recognizes the fungal cell wall component β-glucan, as well as some component(s) in house dust mite (HDM) extract. However, the roles of Dectin-1 in HDM-induced allergic airway inflammation remain unclear. In this study, we used Dectin-1-deficient (Clec7a^-/-) mice to examine whether Dectin-1 is involved in HDM-induced allergic airway inflammation. We found that HDM-induced eosinophil and neutrophil recruitment into the airways was significantly attenuated in Clec7a^-/- mice compared with that in wild-type mice. In addition, HDM-induced IL-5, IL-13, and IL-17 production from mediastinum lymph node cells was reduced in HDM-sensitized Clec7a^-/- mice. Dectin-1 was expressed on CD11b⁺ dendritic cells (DCs), an essential DC subset for the development of allergic inflammation, but not on CD103⁺ DCs, plasmacytoid DCs, or lung epithelial cells. Transcriptome analysis revealed that the expression of chemokine/chemokine receptors, including CCR7, which is indispensable for DC migration to draining lymph nodes, was decreased in Clec7a^-/- DCs. In accordance with these results, the number of HDM-labeled CD11b⁺ DCs in mediastinum lymph nodes was significantly reduced in Clec7a^-/- mice compared with wild-type mice. Taken together, these results suggest that Dectin-1 expressed on CD11b⁺ DCs senses some molecule(s) in HDM extract and plays a critical role in the induction of HDM-induced allergic airway inflammation by inducing the expression of chemokine/chemokine receptors in DCs.

Mycobacterium vaccae Nebulization Can Protect against Asthma in Balb/c Mice by Regulating Th9 Expression

Asthma is a heterogeneous disease characterized by chronic airway inflammation. CD4(+) T-helper 9 (Th9) cells are closely linked to asthma, helping to regulate inflammation and immunity. Epidemiological studies showed that mycobacteria infections are negatively associated with asthma. Our previous research showed that inactivated Mycobacterium phlei nebulization alleviated the airway hyperresponsiveness and inflammation of asthma. However, the relationship between Th9 cells and mycobacteria remains unknown. Here, we evaluated the relationship between Mycobacterium vaccae nebulization and Th9 cells in asthmatic mice. Eighteen Balb/c mice were randomized into 3 groups of 6 mice each (normal control group, asthma control group, and nebulization asthma group [Neb. group]). The Neb. group was nebulized with M. vaccae one month before establishment of the asthmatic model with ovalbumin (OVA) sensitization, and the normal and asthma control groups were nebulized with phosphate-buffered saline. The hyperresponsiveness of the mouse airways was assessed using a non-invasive lung function machine. Lung airway inflammation was evaluated by hematoxylin and eosin and periodic acid-Schiff staining. Cytokine interlukin-9 (IL-9) concentration and OVA-specific IgE in the bronchoalveolar lavage fluid were measured by enzyme-linked immunosorbent assays. The percentages of γδTCR+ CD3+, IL-9+CD3+, IL-10+CD3+ lymphocytes, and IL9+γδT and IL-10+γδT cells were detected by flow cytometry. The airway inflammation and concentration of IL-9 and OVA-specific IgE were significantly reduced in the Neb. group compared to the asthma control group. The Neb. group had lower airway hyperresponsiveness, percentages of γδTCR+CD3+ and IL-9+CD3+ lymphocytes, and IL9+γδT cells, and higher percentages of IL-10+CD3+ lymphocytes and IL-10+γδT cells compared to the asthma control group. Thus, mouse bronchial asthma could be prevented by M. vaccae nebulization. The mechanism could involve M. vaccae-mediated effects on induction of IL-9 secretion and suppression of IL-10 secretion from γδT cells. γδT cells showed prominent IL-10 expression, indicating that they possibly belong to the Th9 family.

Metainflammation in Diabetic Coronary Artery Disease: Emerging Role of Innate and Adaptive Immune Responses

Globally, noncommunicable chronic diseases such as Type-2 Diabetes Mellitus (T2DM) and Coronary Artery Disease (CAD) are posing a major threat to the world. T2DM is known to potentiate CAD which had led to the coining of a new clinical entity named diabetic CAD (DM-CAD), leading to excessive morbidity and mortality. The synergistic interaction between these two comorbidities is through sterile inflammation which is now being addressed as metabolic inflammation or metainflammation, which plays a pivotal role during both early and late stages of T2DM and also serves as a link between T2DM and CAD. This review summarises the current concepts on the role played by both innate and adaptive immune responses in setting up metainflammation in DM-CAD. More specifically, the role played by innate pattern recognition receptors (PRRs) like Toll-like receptors (TLRs), NOD1-like receptors (NLRs), Rig-1-like receptors (RLRs), and C-type lectin like receptors (CLRs) and metabolic endotoxemia in fuelling metainflammation in DM-CAD would be discussed. Further, the role played by adaptive immune cells (Th1, Th2, Th17, and Th9 cells) in fuelling metainflammation in DM-CAD will also be discussed.

Host response mechanisms in periodontal diseases

Periodontal diseases usually refer to common inflammatory disorders known as gingivitis and periodontitis, which are caused by a pathogenic microbiota in the subgingival biofilm, including Porphyromonas gingivalis, Aggregatibacter actinomycetemcomitans, Tannerella forsythia and Treponema denticola that trigger innate, inflammatory, and adaptive immune responses. These processes result in the destruction of the tissues surrounding and supporting the teeth, and eventually in tissue, bone and finally, tooth loss. The innate immune response constitutes a homeostatic system, which is the first line of defense, and is able to recognize invading microorganisms as non-self, triggering immune responses to eliminate them. In addition to the innate immunity, adaptive immunity cells and characteristic cytokines have been described as important players in the periodontal disease pathogenesis scenario, with a special attention to CD4⁺ T-cells (T-helper cells). Interestingly, the T cell-mediated adaptive immunity development is highly dependent on innate immunity-associated antigen presenting cells, which after antigen capture undergo into a maturation process and migrate towards the lymph nodes, where they produce distinct patterns of cytokines that will contribute to the subsequent polarization and activation of specific T CD4+ lymphocytes. Skeletal homeostasis depends on a dynamic balance between the activities of the bone-forming osteoblasts (OBLs) and bone-resorbing osteoclasts (OCLs). This balance is tightly controlled by various regulatory systems, such as the endocrine system, and is influenced by the immune system, an osteoimmunological regulation depending on lymphocyte- and macrophage-derived cytokines. All these cytokines and inflammatory mediators are capable of acting alone or in concert, to stimulate periodontal breakdown and collagen destruction via tissue-derived matrix metalloproteinases, a characterization of the progression of periodontitis as a stage that presents a significantly host immune and inflammatory response to the microbial challenge that determine of susceptibility to develop the destructive/progressive periodontitis under the influence of multiple behavioral, environmental and genetic factors.

Emerging monoclonal antibodies as targeted innovative therapeutic approaches to asthma

Asthma is characterized by discordant responses among cells of the adaptive and innate immune systems. This interplay involves a complex pattern of cytokine-driven processes resulting in cell migration and recruitment, inflammation, and proliferative states. The significant majority of asthmatic patients respond well to conventional inhaled treatments. However, about 5% of asthmatics have severe refractory asthma and account for 50% of the health expenditure on asthma. Human(ized) monoclonal antibodies (hMabs) targeting inflammatory pathways are promising therapeutic agents in asthma management. The anti-IgE hMab omalizumab was the first biologic treatment approved for the treatment of allergic asthma. Potential future strategies and targets include interleukin (IL)-5, IL-4, and IL-13, anti-TSLP, IL-25, and IL-33. hMabs targeting IL-5 have shown great promise in severe refractory asthma with a persisting eosinophilia, and clinical trials with hMabs against IL-13 and IL4Rα have also shown clinical benefit. Studies of hMabs against other cytokines in severe asthma are under way.

Early-Life Exposure to Clostridium leptum Causes Pulmonary Immunosuppression

INTRODUCTION

Low Clostridium leptum levels are a risk factor for the development of asthma. C. leptum deficiency exacerbates asthma; however, the impact of early-life C. leptum exposure on cesarean-delivered mice remains unclear. This study is to determine the effects of early-life C. leptum exposure on asthma development in infant mice.

METHODS

We exposed infant mice to C. leptum (fed-CL) and then induced asthma using the allergen ovalbumin (OVA).

RESULTS

Fed-CL increased regulatory T (Treg) cells in cesarean-delivered mice compared with vaginally delivered mice. Compared with OVA-exposed mice, mice exposed to C. leptum + OVA did not develop the typical asthma phenotype, which includes airway hyper-responsiveness, cell infiltration, and T helper cell subset (Th1, Th2, Th9, Th17) inflammation. Early-life C. leptum exposure induced an immunosuppressive environment in the lung concurrent with increased Treg cells, resulting in the inhibition of Th1, Th2, Th9, and Th17 cell responses.

CONCLUSION

These findings demonstrate a mechanism whereby C. leptum exposure modulates adaptive immunity and leads to failure to develop asthma upon OVA sensitization later in life.

Severe atopic dermatitis is characterized by selective expansion of circulating TH2/TC2 and TH22/TC22, but not TH17/TC17, cells within the skin-homing T-cell population

BACKGROUND

Past studies of blood T-cell phenotyping in patients with atopic dermatitis (AD) have provided controversial results and were mostly performed before the identification of TH9, TH17, and TH22 T-cell populations in human subjects.

OBJECTIVE

We sought to quantify TH1, TH2, TH9, TH17, and TH22 T-cell populations and corresponding CD8(+) T-cell subsets in both cutaneous lymphocyte antigen (CLA)-positive and CLA(-) T-cell subsets in patients with AD and control subjects.

METHODS

We studied 42 adults with severe AD (mean SCORAD score, 65) and 25 healthy subjects using an 11-color flow cytometric antibody panel. Frequencies of IFN-γ-, IL-22-, IL-13-, IL-17-, and IL-9-producing CD4(+) and CD8(+) T cells were compared in CLA(-) and CLA(+) populations.

RESULTS

We measured increased TH2/TC2/IL-13(+) and TH22/TC22/IL-22(+) populations (P < .1) in patients with severe AD versus control subjects, with significant differences in CLA(+) T-cell numbers (P < .01). A significantly lower frequency of CLA(+) IFN-γ-producing cells was observed in patients with AD, with no significant differences in CLA(-) T-cell numbers. The CLA(+) TH1/TH2 and TC1/TC2 ratio was highly imbalanced in patients with AD (10 vs 3 [P = .005] and 19 vs 7 [P < .001], respectively). Positive correlations were found between frequencies of IL-13- and IL-22-producing CD4(+) and CD8(+) T cells (r = 0.5 and 0.8, respectively; P < .0001), and frequencies of IL-13-producing CLA(+) cells were also correlated with IgE levels and SCORAD scores. Patients with AD with skin infections had higher CD4(+) IL-22(+) and IL-17(+) cell frequencies, which were highly significant among CLA(-) cells (IL-22: 3.7 vs 1.7 [P < .001] and IL-17: 1.7 vs 0.6 [P < .001]), with less significant effects among CLA(+) T cells (IL-22: 11 vs 7.5, P = .04).

CONCLUSIONS

Severe AD is accompanied by expansion of skin-homing TH2/TC2 and TH22/TC22 subsets with lower TH1/TC1 frequencies. These data create a critical basis for studying alterations in immune activation in adults and pediatric patients with AD.

Cell-mediated immune responses to respiratory syncytial virus infection: magnitude, kinetics, and correlates with morbidity and age

We evaluated the cell-mediated immune (CMI) response to RSV acute infection including the magnitude, kinetics and correlates with morbidity and age. Twenty-nine RSV-infected patients with mean ± SD age of 15 ± 14 months were enrolled during their first week of disease. Th1, Th2, Th9, Th17 and Th22 responses were measured at entry and 2 and 6 weeks later. All subjects were hospitalized for a median (range) of 5 (3-11) days. RSV-specific effector and memory Th1 CMI measured by lymphocyte proliferation and IFNγ ELISPOT significantly increased over time (P ≤ 0.03). In contrast, Th22 responses decreased over time (P ≤ 0.03). Other changes did not reach statistical significance. The severity of RSV disease measured by the length of hospitalization positively correlated with the magnitude of Th9, Th22 and TNFα inflammatory responses (rho ≥ 0.4; P ≤ 0.04) and negatively with memory CMI (rho = -0.45; P = 0.04). The corollary of this observation is that robust Th1 and/or low Th9, Th22, and TNFα inflammatory responses may be associated with efficient clearance of RSV infection and therefore desirable characteristics of an RSV vaccine. Young age was associated with low memory and effector Th1 responses (rho ≥ 0.4; P ≤ 0.04) and high Th2, Th9, Th17, Th22 and TNFα inflammatory responses (rho ≤ -0.4; P ≤ 0.04), indicating that age at vaccination may be a major determinant of the CMI response pattern.

Possible pathogenic role of T helper type 9 cells and interleukin (IL)-9 in atopic dermatitis

T helper type 9 (Th9) cells are a novel identified subset of CD4(+) T helper cells, which could partly contribute to allergic inflammation, while the precise contribution of Th9 cells in atopic dermatitis (AD) remains unknown. We aimed to explore the possible role of Th9 cells in AD pathogenesis. The Th9 cell percentage, transcription factor PU.1 and cytokine interleukin (IL)-9 mRNA levels, as well as IL-9 serum concentration in peripheral circulation, were measured in AD patients, psoriasis patients and healthy controls. The Th9 cell percentage, PU.1 and IL-9 expression levels of AD patients were all increased significantly compared with the other two control groups (P < 0·01), and correlated positively with SCORing Atopic Dermatitis index, serum immunoglobulin (Ig)E and thymus- and activation-regulated chemokine (TARC) levels (P < 0·05). In simple AD patients and AD patients complicated by allergic rhinitis or asthma, there were no significant differences in the Th9 cell percentage, PU.1 and IL-9 expression levels between them. At the same time, IL-9 and vascular endothelial growth factor (VEGF) mRNA levels were detected in AD lesions and normal skin samples, which were both distinctly elevated in AD lesions, and there was a positive association between them (P < 0·01). Keratinocytes were cultured with IL-9 stimulation and the secretion of VEGF was detected. IL-9 can promote the secretion of VEGF by keratinocytes in a time- and dose-dependent manner. In conclusion, the expansion of the Th9 cell subset, up-regulation of the PU.1 transcription factor and increased secretion of the IL-9 cytokine may contribute to the pathogenesis of AD, which may be supported by the increased release of VEGF by keratinocyes after IL-9 stimulation.

IL-4-, TGF-β-, and IL-1-dependent expansion of parasite antigen-specific Th9 cells is associated with clinical pathology in human lymphatic filariasis

Th9 cells are a subset of CD4(+) T cells, shown to be important in allergy, autoimmunity, and antitumor responses; however, their role in human infectious diseases has not been explored in detail. We identified a population of IL-9 and IL-10 coexpressing cells (lacking IL-4 expression) in normal individuals. These cells respond to antigenic and mitogenic stimulation, but are distinct from IL-9(+) Th2 cells. We also demonstrate that these Th9 cells exhibit Ag-specific expansion in a chronic helminth infection (lymphatic filariasis). Comparison of Th9 responses reveals that individuals with pathology associated with filarial infection exhibit significantly expanded frequencies of filarial Ag-induced Th9 cells, but not of IL9(+)Th2 cells in comparison with filarial-infected individuals without associated disease. Moreover, the per cell production of IL-9 is significantly higher in Th9 cells compared with IL9(+)Th2 cells, indicating that the Th9 cells are the predominant CD4(+) T cell subset producing IL-9 in the context of human infection. This expansion was reflected in elevated Ag-stimulated IL-9 cytokine levels in whole blood culture supernatants. Finally, the frequencies of Th9 cells correlated positively with the severity of lymphedema (and presumed inflammation) in filarial-diseased individuals. This expansion of Th9 cells was dependent on IL-4, TGF-β, and IL-1 in vitro. We have therefore identified an important human CD4(+) T cell subpopulation coexpressing IL-9 and IL-10, but not IL-4, the expansion of which is associated with disease in chronic lymphatic filariasis and could potentially have an important role in the pathogenesis of other inflammatory disorders.

Cyclooxygenase-2 inhibits T helper cell type 9 differentiation during allergic lung inflammation via down-regulation of IL-17RB

RATIONALE

Helper CD4(+) T cell subsets, including IL-9- and IL-10-producing T helper cell type 9 (Th9) cells, exist under certain inflammatory conditions. Cyclooxygenase (COX)-1 and COX-2 play important roles in allergic lung inflammation and asthma. It is unknown whether COX-derived eicosanoids regulate Th9 cells during allergic lung inflammation.

OBJECTIVES

To determine the role of COX metabolites in regulating Th9 cell differentiation and function during allergic lung inflammation.

METHODS

COX-1(-/-), COX-2(-/-), and wild-type (WT) mice were studied in an in vivo model of ovalbumin-induced allergic inflammation and an in vitro model of Th9 differentiation using flow cytometry, cytokine assays, confocal microscopy, real-time PCR, and immunoblotting. In addition, the role of specific eicosanoids and their receptors was examined using synthetic prostaglandins (PGs), selective inhibitors, and siRNA knockdown.

MEASUREMENTS AND MAIN RESULTS

Experimental endpoints were not different between COX-1(-/-) and WT mice; however, the percentage of IL-9(+) CD4(+) T cells was increased in lung, bronchoalveolar lavage fluid, lymph nodes, and blood of allergic COX-2(-/-) mice relative to WT. Bronchoalveolar lavage fluid IL-9 and IL-10, serum IL-9, and lung IL-17RB levels were significantly increased in allergic COX-2(-/-) mice or in WT mice treated with COX-2 inhibitors. IL-9, IL-10, and IL-17RB expression in vivo was inhibited by PGD2 and PGE2, which also reduced Th9 cell differentiation of murine and human naive CD4(+) T cells in vitro. Inhibition of protein kinase A significantly increased Th9 cell differentiation of naive CD4(+) T cells isolated from WT mice in vitro.

CONCLUSIONS

COX-2-derived PGD2 and PGE2 regulate Th9 cell differentiation by suppressing IL-17RB expression via a protein kinase A-dependent mechanism.

Chronic IL9 and IL-13 exposure leads to an altered differentiation of ciliated cells in a well-differentiated paediatric bronchial epithelial cell model

Asthma is a chronic inflammatory disease characterised by airways remodelling. In mouse models IL-9 and IL-13 have been implicated in airways remodelling including mucus hypersecretion and goblet cell hyperplasia. Their role, especially that of IL-9, has been much less studied in authentic human ex vivo models of the bronchial epithelium from normal and asthmatic children. We assessed the effects of IL-9, IL-13 and an IL-9/IL-13 combination, during differentiation of bronchial epithelial cells from normal (n = 6) and asthmatic (n = 8) children. Cultures were analysed for morphological markers and factors associated with altered differentiation (MUC5AC, SPDEF and MMP-7). IL-9, IL-9/IL-13 combination and IL-13 stimulated bronchial epithelial cells from normal children had fewer ciliated cells [14.8% (SD 8.9), p = 0.048, 12.4 (SD 6.1), p = 0.016 and 7.3% (SD 6.6), p = 0.031] respectively compared with unstimulated [(21.4% (SD 9.6)]. IL-9 stimulation had no effect on goblet cell number in either group whereas IL-9/IL-13 combination and IL-13 significantly increased goblet cell number [24.8% (SD 8.8), p = 0.02), 32.9% (SD 8.6), p = 0.007] compared with unstimulated normal bronchial cells [(18.6% (SD 6.2)]. All stimulations increased MUC5AC mRNA in bronchial epithelial cells from normal children and increased MUC5AC mucin secretion. MMP-7 localisation was dysregulated in normal bronchial epithelium stimulated with Th2 cytokines which resembled the unstimulated bronchial epithelium of asthmatic children. All stimulations resulted in a significant reduction in transepithelial electrical resistance values over time suggesting a role in altered tight junction formation. We conclude that IL-9 does not increase goblet cell numbers in bronchial epithelial cell cultures from normal or asthmatic children. IL-9 and IL-13 alone and in combination, reduce ciliated cell numbers and transepithelial electrical resistance during differentiation of normal epithelium, which clinically could inhibit mucociliary clearance and drive an altered repair mechanism. This suggests an alternative role for IL-9 in airways remodelling and reaffirms IL-9 as a potential therapeutic target.

Changes in CD4+ T lymphocyte subsets and clinical outcomes of hepatitis B virus infection

Various clinical manifestations may develop in people infected with hepatitis B virus (HBV), ranging from asymptomatic infection to acute severe hepatitis B. Some infections become self-limiting when the virus is cleared, while approximately 90% of children and 10% of adults become HBV carriers or patients with chronic hepatitis B, who can further develop cirrhosis and hepatocellular carcinoma. CD4⁺ T lymphocytes play a central role in anti-infection immunity and can be divided into different subsets, including Th1, Th2, Treg, Th17, Th22, Th9 and Tfh. These T lymphocyte subsets all come from the same progenitor cells (Th0), although they have particular differentiation pathway and secrete different kinds of cytokines. Furthermore, they are able to interact with each other and change into each other. Particularly, the balances of Th1/Th2 and Th17/Treg play a vital role in determining the clinical outcomes of HBV infection.

Targeting interleukins to treat severe asthma

Severe asthma is thought to be a heterogeneous disease with different phenotypes predicated primarily on the nature of the inflammatory cell infiltrate and response to corticosteroid therapy. This group of patients often has refractory disease with an associated increase in morbidity and mortality, and there remains a need for better therapies for severe asthmatics. Inflammatory changes in asthma are driven by immune mechanisms, within which interleukins play an integral role. Interleukins are cell-signaling cytokines that are produced by a variety of cells, predominantly T cells. Knowledge about their actions has improved the understanding of the pathogenesis of asthma and provided potential targets for novel therapies. To date, this has not translated into clinical use. However, there are ongoing clinical trials that use monoclonal antibodies for various interleukins, some of which have shown to be promising in Phase II studies.

Plasticity within the αβ⁺CD4⁺ T-cell lineage: when, how and what for?

Following thymic output, αβ⁺CD4⁺ T cells become activated in the periphery when they encounter peptide-major histocompatibility complex. A combination of cytokine and co-stimulatory signals instructs the differentiation of T cells into various lineages and subsequent expansion and contraction during an appropriate and protective immune response. Our understanding of the events leading to T-cell lineage commitment has been dominated by a single fate model describing the commitment of T cells to one of several helper (T(H)), follicular helper (T(FH)) or regulatory (T(REG)) phenotypes. Although a single lineage-committed and dedicated T cell may best execute a single function, the view of a single fate for T cells has recently been challenged. A relatively new paradigm in αβ⁺CD4⁺ T-cell biology indicates that T cells are much more flexible than previously appreciated, with the ability to change between helper phenotypes, between helper and follicular helper, or, most extremely, between helper and regulatory functions. In this review, we comprehensively summarize the recent literature identifying when T(H) or T(REG) cell plasticity occurs, provide potential mechanisms of plasticity and ask if T-cell plasticity is beneficial or detrimental to immunity.

Evidence supporting a protective role for th9 and th22 cytokines in human and experimental periapical lesions

INTRODUCTION

The development of periapical granulomas is dependent on the host response and involves Th1, Th2, Th17, and Treg-related cytokines. The discovery of new Th9 and Th22 subsets, with important immunomodulatory roles mediated by interleukin (IL)-9 and IL-22, respectively, emphasizes the need for reevaluation of current cytokine paradigms in context of periapical lesions. We investigated the expression of IL-9 and IL-22 in active and stable human granulomas and throughout experimental lesion development in mice.

METHODS

Periapical granulomas (N = 83) and control specimens (N = 24) were evaluated regarding the expression of IL-9 and IL-22 via real-time polymerase chain reaction. Experimental periapical lesions were induced in mice (pulp exposure and bacterial inoculation) and the lesions evolution correlation with IL-9 and IL-22 expression kinetics was evaluated.

RESULTS

IL-9 and IL-22 mRNA expression was higher in periapical lesions than in control samples; higher levels of IL-9 and IL-22 were observed in inactive than in active lesions. In the experimental lesions model, increasing levels of IL-9 and IL-22 mRNA were detected in the lesions, and inverse correlations were found between IL-9 and IL-22 and the increase of lesion area in the different time point intervals.

CONCLUSIONS

Our results suggest that Th9 and Th22 pathways may contribute to human and experimental periapical lesion stability.

Severe asthma: advances in current management and future therapy

Effective treatment of severe asthma is a major unmet need because patients' symptoms are not controlled on maximum treatment with inhaled therapy. Asthma symptoms can be poorly controlled because of poor adherence to controller therapy, and this might be addressed by using combination inhalers that contain a corticosteroid and long-acting β(2)-agonist as reliever therapy in addition to maintenance treatment. New bronchodilators with a longer duration of action are in development, and recent studies have demonstrated the benefit of a long-acting anticholinergic bronchodilator in addition to β(2)-agonists in patients with severe asthma. Anti-IgE therapy is beneficial in selected patients with severe asthma. Several new blockers of specific mediators, including prostaglandin D(2), IL-5, IL-9, and IL-13, are also in clinical trials and might benefit patients with subtypes of severe asthma. Several broad-spectrum anti-inflammatory therapies that target neutrophilic inflammation are in clinical development for the treatment of severe asthma, but adverse effects after oral administration might necessitate inhaled delivery. Macrolides might benefit some patients with infection by atypical bacteria, but recent results are not encouraging, although there could be an effect in patients with predominant neutrophilic asthma. Corticosteroid resistance is a major problem in patients with severe asthma, and several molecular mechanisms have been described that might lead to novel therapeutic approaches, including drugs that could reverse this resistance, such as theophylline and nortriptyline. In selected patients with severe asthma, bronchial thermoplasty might be beneficial, but thus far, clinical studies have not been encouraging. Finally, several subtypes of severe asthma are now recognized, and in the future, it will be necessary to find biomarkers that predict responses to specific forms of therapy.

Staphylococcus aureus directly activates eosinophils via platelet-activating factor receptor

Colonization by SA is associated with exacerbation of AD. Eosinophilic inflammation is a cardinal pathological feature of AD, but little is known about possible direct interaction between SA and eosinophils. PAFR appears to be involved in phagocytosis of Gram-positive bacteria by leukocytes. The objective of this study was to investigate whether SA directly induces eosinophil effector functions via PAFR in the context of AD pathogenesis. Peripheral blood eosinophils were cultured with heat-killed SA, and EDN release, superoxide generation, and adhesion to fibronectin-coated plates were measured. Cytokines, released in the supernatants, were quantified by multiplex bead immunoassays. FISH-labeled SA was incubated with eosinophils and visualized by confocal laser-scanning microscopy. PAFR-blocking peptide and PAFR antagonists were tested for inhibitory effects on SA-induced reactions. SA induced EDN release and superoxide generation by eosinophils in a dose-dependent manner. IL-5 significantly enhanced SA-induced EDN release. IL-5 and IL-17A significantly enhanced SA-induced superoxide generation. SA enhanced eosinophil adhesion to fibronectin, which was blocked by anti-CD49d, and induced eosinophil secretion of various cytokines/chemokines (IL-2R, IL-9, TNFR, IL-1 β, IL-17A, IP-10, TNF-α, PDGF-bb, VEGF, and FGF-basic). After incubation of eosinophils with SA, FISH-labeled SA was visualized in the eosinophils' cytoplasm, indicating phagocytosis. A PAFR-blocking peptide and two PAFR antagonists completely inhibited those reactions. In conclusion, SA directly induced eosinophil activation via PAFR. Blockade of PAFR may be a novel, therapeutic approach for AD colonized by SA.

CD4⁺T cells: differentiation and functions

CD4⁺T cells are crucial in achieving a regulated effective immune response to pathogens. Naive CD4⁺T cells are activated after interaction with antigen-MHC complex and differentiate into specific subtypes depending mainly on the cytokine milieu of the microenvironment. Besides the classical T-helper 1 and T-helper 2, other subsets have been identified, including T-helper 17, regulatory T cell, follicular helper T cell, and T-helper 9, each with a characteristic cytokine profile. For a particular phenotype to be differentiated, a set of cytokine signaling pathways coupled with activation of lineage-specific transcription factors and epigenetic modifications at appropriate genes are required. The effector functions of these cells are mediated by the cytokines secreted by the differentiated cells. This paper will focus on the cytokine-signaling and the network of transcription factors responsible for the differentiation of naive CD4⁺T cells.

Transcriptional characteristics of CD4 T cells in young asthmatic children: RORC and FOXP3 axis

Background

Asthma is a chronic inflammatory disorder, hypothetically caused by autoreactive Th2 cells, whereas Th1 and regulatory T cells may confer protection. The development of Th subpopulations is dependent on the expression of lineage-specific transcription factors.

Purpose

This study aimed to assess the balance of CD4⁺ T cell populations in asthmatic children.

Methods

Peripheral blood mononuclear cells (PBMC) mRNA expression was assessed in 30 asthmatic children (18 patients with mild asthma and 12 with moderate asthma). Real-time polymerase chain reaction (RT-PCR) quantified TBX21, GATA-3, RORC, FOXP3, and EBI3 mRNA expression. Intracellular cytokine expression of IL-2, IL-4, IL-10, and IFN-γ in CD4⁺ T cells in asthmatic children was measured by flow cytometry. IL-6 and IL-17 cytokines were assessed in serum by enzyme-linked immunosorbent assay (ELISA).

Results

A significant increase was found in the percentage of CD4⁺ and CD8⁺ T cell-producing IL-4, IL-6, and IL-17. A decreased percentage of CD4⁺ producing IFN-γ in asthmatic children was found. Expression of GATA-3 (Th2), retinoid-related orphan receptor C (RORC) (Th17), and EBI3 were increased in asthmatic patients compared to healthy controls. Expression of FOXP3 (Treg) and TBX21 (Th1) were decreased (P < 0.0001 and P < 0.0001) in asthmatic children. Analysis of transcription factor ratios revealed an increase in the RORC/FOXP3 (P = 0.0001), and a significant decrease of TBX21/GATA-3 (P = 0.0001) ratios in patients with asthma.

Conclusion

Young asthmatics were characterized by increased IL-4 production and low IFN-γ synthesis. The increased serum IL-17 and IL-6 levels sustained an inflammatory environment in young asthmatics. The results indicate that FOXP3 and RORC mRNA expression could be associated with the sustained inflammatory process, transduced by low immune tolerance by Treg cells. The TBX21/GATA-3 and RORC/FOXP3 ratios dysregulation in asthmatics is consistent with the plasticity existing between Th1, Th17, and Treg cells during inflammation.

Monoclonal antibodies for the treatment of asthma

Asthma is a chronic inflammatory disease of the airways which can have a detrimental effect on quality of life and in extreme cases cause death. Although the majority of patients can control their asthma symptoms with a combination of steroids and beta agonists there is still a group of patients whose asthma remains symptomatic despite the best available treatment. These severe asthmatic patients represent the unmet medical need in asthma and are the focus of those developing novel monoclonal antibody based drugs. The complex networks of cytokines and cells involved in the pathology of asthma provide plenty of scope for intervention with monoclonal antibody based drugs which are able to block cytokine or chemokine receptor interactions, deplete cells expressing a specific receptor or block cell/cell interactions. At present anti-IgE (Xolair©) is the only monoclonal antibody based drug approved for the treatment of asthma. However, a number of other antibody based drugs have been clinically tested in asthma including anti-IL-5, anti-IL-4, anti-IL-13, anti-TNFα, anti-CCR3, anti-CCR4 and anti-OX40L. This review will examine the development of these monoclonal antibody based therapies. Since many of these therapies have targeted key pathways in asthma pathology these studies provide information on patient stratification and asthma pathology.