IL-9 and Th9 cells: progress and challenges

CD4+ T-cell subsets in autoimmune hepatitis: A review

Autoimmune hepatitis (AIH) is a chronic autoimmune liver disease that can lead to hepatocyte destruction, inflammation, liver fibrosis, cirrhosis, and liver failure. The diagnosis of AIH requires the identification of lymphoblast cell interface hepatitis and serum biochemical abnormalities, as well as the exclusion of related diseases. According to different specific autoantibodies, AIH can be divided into AIH-1 and AIH-2. The first-line treatment for AIH is a corticosteroid and azathioprine regimen, and patients with liver failure require liver transplantation. However, the long-term use of corticosteroids has obvious side effects, and patients are prone to relapse after drug withdrawal. Autoimmune diseases are characterized by an imbalance in immune tolerance of self-antigens, activation of autoreactive T cells, overactivity of B cells, and increased production of autoantibodies. CD4+ T cells are key players in adaptive immunity and can secrete cytokines, activate B cells to produce antibodies, and influence the cytotoxicity of CD8+ T cells. According to their characteristics, CD4+ T cells can be divided into different subsets. In this review, we discuss the changes in T helper (Th)1, Th2, Th17, Th9, Th22, regulatory T cell, T follicular helper, and T peripheral helper cells and their related factors in AIH and discuss the therapeutic potential of targeting CD4+ T-cell subsets in AIH.

Mesenchymal stem cells modulate IL-17 and IL-9 production induced by Th17-inducing cytokine conditions in autoimmune arthritis: an explorative analysis

BACKGROUND

The importance of proinflammatory T-cells and their cytokine production in patients with autoimmune arthritis has been widely described. Due to their immunomodulatory properties, mesenchymal stem cells (MSCs) have come into focus as a potential therapeutic concept. The aim of this study was to investigate the influence of MSCs on the phenotype, cytokine profile, and functionality of naive and non-naive CD4+ T-cells from healthy donors (HD) and patients with autoimmune arthritis under Th17-cytokine polarizing conditions in an explorative way using a transwell system prohibiting any cell-cell-contact.

METHODS

Magnetically isolated naive and non-naive CD4+ T-cells were stimulated under Th17-polarizing proinflammatory cytokine conditions in presence and absence of bone marrow derived mesenchymal stromal cells (MSCs). After an incubation period of 6 days, the proportions of the T-cell subpopulations TEMRA (CD45RA+CD27-), memory (CD45RA-CD27+), effector (CD45RA-CD27-) and naive cells (CD45RA+CD27+) were determined. Quantitative immunofluorescence intensity was used as a measure for IL-9, IL-17 and IFN-γ production in each subpopulation.

RESULTS

In isolated naive CD4+ T-cells from HD and patients, MSCs suppressed the differentiation of naive towards an effector phenotype while memory and naive cells showed higher percentages in culture with MSCs. In patients, MSCs significantly decreased the proportion of IL-9 and IL-17 producing effector T-cells. MSCs also reduced IFN-γ production in the naive and memory phenotype from HD.

CONCLUSION

The results of the study indicate significant immunomodulatory properties of MSCs, as under Th17-polarizing conditions MSCs are still able to control T-cell differentiation and proinflammatory cytokine production in both HD and patients with autoimmune arthritis.

Bioactive and health-promoting properties of enzymatic hydrolysates of legume proteins: a review

This study comprehensively reviewed the effect of controlled enzymatic hydrolysis on the bioactivity of pulse protein hydrolysates (PPHs). Proteolysis results in the partial structural unfolding of pulse proteins with an increase in buried hydrophobic groups of peptide sequences. The use of PPHs in a dose-dependent manner can enhance free radical scavenging and improve antioxidant activities regarding inhibition of lipid oxidation, ferric reducing power, metal ion chelation, and β-carotene bleaching inhibition. Ultrafiltered peptide fractions with low molecular weights imparted angiotensin-I converting enzyme (ACE) inhibitory effects during in vitro simulated gastrointestinal digestion and in vivo conditions. Ultrasonication, high-pressure pretreatments, and glycosylation as post-treatments can improve the antiradical, antioxidant, and ACE inhibitory activities of PPHs. The electrostatic attachment of pulse peptides to microbial cells can inhibit the growth and activity of bacteria and fungi. Bioactive pulse peptides can reduce serum cholesterol and triglycerides, and inhibit the formation of adipocyte lipid storage, allergenic factors, inflammatory markers, and arterial thrombus without cytotoxicity. The combination of germination and enzymatic hydrolysis can significantly increase the protein digestibility and bioavailability of essential amino acids. Moreover, the utilization and enrichment of bakery and meat products with functional PPHs ensure quality, safety, and health aspects of food products.

T-cell receptor variable region usage in Chagas disease: A systematic review of experimental and human studies

T cells recognize their ligand, the peptide major histocompatibility complex (MHC), via the T-cell receptor (TCR), which is composed of covalently linked α and β or γ and δ chains. This recognition is critical for T-cell ontogeny and controls the selection, activation, and function of T lymphocytes. Specific TCR αβ variable regions have been associated with immunopathogenesis of Chagas disease. Here, we present a systematic review that compiles experimental in vivo and human data regarding the preferential expression of variable alpha (Vα) and variable beta (Vβ) chain regions in Trypanosoma cruzi infection. The original studies indexed in PubMed/Medline, Scopus, and Web of Science databases were screened according to the PRISMA strategy. The analysis showed that expression of TCR Vα subfamilies were evaluated in one human study, and, unlike TCR Vβ, TCR Vα presented a more restricted usage. Despite the great variability in the usage of TCR Vβ regions in human Chagas disease, a down-regulation of TCR Vβ5 expression by T cells from patients in the acute phase of the disease was shown. Opposingly, this TCR region was found overly expressed in CD4+ T cells from chronic Chagas patients. It was also demonstrated that murine Vβ9+ T cells derived from nonlymphoid organs of T. cruzi-infected animals had a modulatory profile, while splenic Vβ9+ T cells produced inflammatory cytokines, indicating that although they display the same TCR Vβ region usage, these cells are functionally distinct. Despite the limitations of few papers and year of publication of the studies, compiling the data derived from them reveals that further investigation of TCR usage will point to their potential role in protective or pathogenic responses, as biomarkers of disease progression, and in the search for dominant peptides potentially useful for the development of vaccines or therapies.

Chagas disease is a neglected tropical disease, caused by infection with Trypanosoma cruzi. Differential expression of certain T-cell receptor (TCR) variable regions has been associated with the immunopathogenesis of Chagas disease. Here, we present a systematic review that compiled experimental in vivo and human data regarding the preferential expression of TCR alpha and beta chain variable regions in Chagas disease. The original studies indexed in the PubMed/Medline, Scopus, and Web of Science databases were screened according to the PRISMA strategy. Despite the great variability in the use of TCR Vβ in T. cruzi infection, the outcomes indicate that there is a down-regulation of TCR Vβ5 expression in T cells from patients in the acute phase of Chagas disease. However, this region is preferentially expressed by CD4+ T cells from chronic Chagas patients. Additionally, it has been demonstrated that murine Vβ9+ T cells derived from nonlymphoid organs displayed a modulatory profile, while splenic Vβ9+ T cells produced inflammatory cytokines, indicating that although they express the same TCR Vβ region, these cells are functionally distinct. Information on TCR expression, specificity and function have critical impact on vaccine design.

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.

Metabolic Profiling of Rheumatoid Arthritis Neutrophils Reveals Altered Energy Metabolism That Is Not Affected by JAK Inhibition

Neutrophils play a key role in the pathophysiology of rheumatoid arthritis (RA) where release of ROS and proteases directly causes damage to joints and tissues. Neutrophil function can be modulated by Janus Kinase (JAK) inhibitor drugs, including tofacitinib and baricitinib, which are clinically effective treatments for RA. However, clinical trials have reported increased infection rates and transient neutropenia during therapy. The subtle differences in the mode of action, efficacy and safety of JAK inhibitors have been the primary research topic of many clinical trials and systematic reviews, to provide a more precise and targeted treatment to patients. The aim of this study was to determine both the differences in the metabolome of neutrophils from healthy controls and people with RA, and the effect of different JAK inhibitors on the metabolome of healthy and RA neutrophils. Isolated neutrophils from healthy controls (HC) (n = 6) and people with RA (n = 7) were incubated with baricitinib, tofacitinib or a pan-JAK inhibitor (all 200 ng/mL) for 2 h. Metabolites were extracted, and 1H nuclear magnetic resonance (NMR) was applied to study the metabolic changes. Multivariate analyses and machine learning models showed a divergent metabolic pattern in RA neutrophils compared to HC at 0 h (F1 score = 86.7%) driven by energy metabolites (ATP, ADP, GTP and glucose). No difference was observed in the neutrophil metabolome when treated with JAK inhibitors. However, JAK inhibitors significantly inhibited ROS production and baricitinib decreased NET production (p < 0.05). Bacterial killing was not impaired by JAK inhibitors, indicating that the effect of JAK inhibitors on neutrophils can inhibit joint damage in RA without impairing host defence. This study highlights altered energy metabolism in RA neutrophils which may explain the cause of their dysregulation in inflammatory disease.

Deleterious Role of Th9 Cells in Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal lung disease of unknown etiology. Immune disorders play an important role in IPF pathogenesis. Here, we show that Th9 cells differentiate and activate in the lung tissue of patients with IPF and bleomycin (BLM)-induced lung fibrosis mice. Moreover, we found that Th9 cells promote pulmonary fibrosis in two ways. On the one hand, Th9 cells promote fibroblast differentiation, activation, and collagen secretion by secreting IL-9. On the other hand, they promote differentiation of Th0 cells into Th2 cells by secreting IL-4. Th9 cells and Th2 cells can promote each other, accelerating the Th1/Th2 imbalance and eventually forming a positive feedback of pulmonary fibrosis. In addition, we found that neutralizing IL-9 in both preventive and therapeutic settings ameliorates bleomycin-induced pulmonary fibrosis. Furthermore, we identified several critical signaling pathways involved in the effect of neutralizing IL-9 on pulmonary fibrosis by proteomics study. From an immunological perspective, we elucidated the novel role and underlying mechanism of Th9 cells in pulmonary fibrosis. Our study suggested that Th9-based immunotherapy may be employed as a treatment strategy for IPF.

Exosomes secreted by palmitic acid-treated hepatocytes promote LX-2 cell activation by transferring miRNA-107

Activation of hepatic stellate cells (HSCs) is a key inducer of liver fibrogenesis in nonalcoholic fatty liver disease (NAFLD). Exosomes play an important role between hepatocytes and HSCs. This study aims to explore the role of exosomes derived from palmitic acid (PA)-treated hepatocytes in regulating HSCs (LX-2 cell) proliferation and activation and the underlying mechanisms. Exosomes were isolated from PA-treated human normal hepatocytes and incubated with LX-2 cells. Cell Counting Kit-8 (CCK-8) was performed to determine LX-2 cell proliferation, and the expression of fibrosis markers α-smooth muscle actin (α-SMA) and collagen type 1 α1 (CoL1A1) were examined to evaluateLX-2 cell activation. PA induced hepatocytes to release more exosomes enriched in miR-107. Mechanically, on the one hand, exosomes from PA-treated hepatocytes shuttled miR-107 to LX-2 cells, where miR-107 activated Wnt signaling by targeting DKK1 and thereby induced LX-2 cell activation; on the other hand, PA-treated hepatocytes derived exosomes also delivered miR-107 to CD4 + T lymphocytes, where miR-107 elevated IL-9 expression by targeting Foxp1, which bound to the IL-9 promoter in CD4 + T cells and suppressed Th9 cell differentiation and reduced IL-9 expression, and thus promoted LX-2 cell activation by activating Raf/MEK/ERK signaling pathway.

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.

Novel Immune Subsets and Related Cytokines: Emerging Players in the Progression of Liver Fibrosis

Liver fibrosis is a pathological process caused by persistent chronic injury of the liver. Kupffer cells, natural killer (NK) cells, NKT cells, and dendritic cells (DCs), which are in close contact with T and B cells, serve to bridge innate and adaptive immunity in the liver. Meanwhile, an imbalanced inflammatory response constitutes a challenge in liver disease. The dichotomous roles of novel immune cells, including T helper 17 (Th17), regulatory T cells (Tregs), mucosa-associated invariant T cells (MAIT), and innate lymphoid cells (ILCs) in liver fibrosis have gradually been revealed. These cells not only induce damage during liver fibrosis but also promote tissue repair. Hence, immune cells have unique, and often opposing, roles during the various stages of fibrosis. Due to this heterogeneity, the treatment, or reversal of fibrosis through the target of immune cells have attracted much attention. Moreover, activation of hepatic stellate cells (HSCs) constitutes the core of fibrosis. This activation is regulated by various immune mediators, including Th17, Th22, and Th9, MAIT, ILCs, and γδ T cells, as well as their related cytokines. Thus, liver fibrosis results from the complex interaction of these immune mediators, thereby complicating the ability to elucidate the mechanisms of action elicited by each cell type. Future developments in biotechnology will certainly aid in this feat to inform the design of novel therapeutic targets. Therefore, the aim of this review was to summarize the role of specific immune cells in liver fibrosis, as well as biomarkers and treatment methods related to these cells.

Critical Roles of Balanced T Helper 9 Cells and Regulatory T Cells in Allergic Airway Inflammation and Tumor Immunity

CD4⁺T helper (Th) cells are important mediators of immune responses in asthma and cancer. When counteracted by different classes of pathogens, naïve CD4⁺T cells undergo programmed differentiation into distinct types of Th cells. Th cells orchestrate antigen-specific immune responses upon their clonal T-cell receptor (TCR) interaction with the appropriate peptide antigen presented on MHC class II molecules expressed by antigen-presenting cells (APCs). T helper 9 (Th9) cells and regulatory T (Treg) cells and their corresponding cytokines have critical roles in tumor and allergic immunity. In the context of asthma and cancer, the dynamic internal microenvironment, along with chronic inflammatory stimuli, influences development, differentiation, and function of Th9 cells and Treg cells. Furthermore, the dysregulation of the balance between Th9 cells and Treg cells might trigger aberrant immune responses, resulting in development and exacerbation of asthma and cancer. In this review, the development, differentiation, and function of Th9 cells and Treg cells, which are synergistically regulated by various factors including cytokine signals, transcriptional factors (TFs), costimulatory signals, microenvironment cues, metabolic pathways, and different signal pathways, will be discussed. In addition, we focus on the recent progress that has helped to achieve a better understanding of the roles of Th9 cells and Treg cells in allergic airway inflammation and tumor immunity. We also discuss how various factors moderate their responses in asthma and cancer. Finally, we summarize the recent findings regarding potential mechanisms for regulating the balance between Th9 and Treg cells in asthma and cancer. These advances provide opportunities for novel therapeutic strategies that are aimed at reestablishing the balance of these cells in the diseases.

Insights into interplay of immunopathophysiological events and molecular mechanistic cascades in psoriasis and its associated comorbidities

Psoriasis is an inflammatory skin disease with complex pathogenesis and multiple etiological factors. Besides the essential role of autoreactive T cells and constellation of cytokines, the discovery of IL-23/Th17 axis as a central signaling pathway has unraveled the mechanism of accelerated inflammation in psoriasis. This has provided insights into psoriasis pathogenesis and revolutionized the development of effective biological therapies. Moreover, genome-wide association studies have identified several candidate genes and susceptibility loci associated with this disease. Although involvement of cellular innate and adaptive immune responses and dysregulation of immune cells have been implicated in psoriasis initiation and maintenance, there is still a lack of unifying mechanism for understanding the pathogenesis of this disease. Emerging evidence suggests that psoriasis is a high-mortality disease with additional burden of comorbidities, which adversely affects the treatment response and overall quality of life of patients. Furthermore, changing trends of psoriasis-associated comorbidities and shared patterns of genetic susceptibility, risk factors and pathophysiological mechanisms manifest psoriasis as a multifactorial systemic disease. This review highlights the recent progress in understanding the crucial role of different immune cells, proinflammatory cytokines and microRNAs in psoriasis pathogenesis. In addition, we comprehensively discuss the involvement of various complex signaling pathways and their interplay with immune cell markers to comprehend the underlying pathophysiological mechanism, which may lead to exploration of new therapeutic targets and development of novel treatment strategies to reduce the disastrous nature of psoriasis and associated comorbidities.

Granuloma formation and tissue pathology in Schistosoma japonicum versus Schistosoma mansoni infections

Schistosomiasis is the most important helminth disease in the world from a public health perspective. S mansoni and S japonicum account for the majority of global intestinal schistosomiasis cases, and the pathogenesis is widely assumed to be fundamentally similar. However, the majority of research on schistosomiasis has been carried out on S mansoni and comparisons between the two species are rarely made. Here, we will discuss aspects of both older and recent literature where such comparisons have been made, with a particular focus on the pathological agent, the host granulomatous response to the egg. Major differences between the two species are apparent in features such as egg production patterns and cellular infiltration; however, it is also clear that even subtle differences in the cascade of various cytokines and chemokines contribute to the different levels of pathology observed between these two main species of intestinal schistosomiasis. A better understanding of such differences at species level will be vital when it comes to the development of new treatment strategies and vaccines.

The Roles of CD8+ T Cell Subsets in Antitumor Immunity

Effector CD8⁺ T cells are typically thought to be a homogenous group of cytotoxic cells that produce interferon-(IFN) γ. However, recent findings have challenged this notion because multiple subsets of CD8⁺ T cells have been described, each with distinct effector functions and cytotoxic potential. These subsets, referred to as the Tc subsets, have also been detected in tumor microenvironments (TMEs), where they potentially influence the antitumor response and patient outcomes. In this review, we highlight the prevalence and roles of Tc subsets in the TME. We also discuss their therapeutic applications in the context of adoptive immunotherapy to treat cancer.

Glycogen synthase kinase-3 promotes T helper type 17 differentiation by promoting interleukin-9 production

T helper type 17 (Th17) cells are recognized as important contributors to the deleterious effects of several neurological and psychiatric diseases. Clarifying mechanisms that control the production of Th17 cells may therefore provide new strategies for developing novel interventions in a broad spectrum of disorders. Th17 cell differentiation is promoted by glycogen synthase kinase-3 (GSK3), but the mechanisms for this are only beginning to be understood. Using T-cell-selective depletion of GSK3β and multiple selective pharmacological GSK3 inhibitors, we found that GSK3 inhibition decreased C-C motif chemokine (ccl)20, C-C motif chemokine receptor (ccr)6, interleukin (IL)-9, Runt-related transcription factor (Runx)1, interferon regulatory factor (Irf)4 and c-maf mRNA expression after 2 days of Th17 cell differentiation in vitro. These effects were found to be independent of the master regulator transcription factor retinoic acid receptor-related orphan receptor γT (RORγT), as GSK3 inhibition still reduced Th17 cell differentiation in RORγT-depleted cells. Because IL-9 was approximately ninefold down-regulated in GSK3β^-/- CD4 cells, we tested if reintroduction of IL-9 during Th17 cell differentiation abolished the inhibition by GSK3 deficiency of Th17 cell differentiation. We found that IL-9 over-expression was sufficient to reverse the inhibition of Th17 cell differentiation by GSK3 inhibition or depletion. We found that IL-9 enhances Th17 cell differentiation in part through signal transducer and activator of transcription 3 (STAT3) activation, and IL-9 also enhances STAT3 binding to the IL-17a promoter. Altogether, these findings suggest that IL-9 might be an important mediator of GSK3β-dependent enhancement of Th17 cell differentiation.

T Lymphocyte-Mediated Liver Immunopathology of Schistosomiasis

The parasitic worms, Schistosoma mansoni and Schistosoma japonicum, reside in the mesenteric veins, where they release eggs that induce a dramatic granulomatous response in the liver and intestines. Subsequently, infection may further develop into significant fibrosis and portal hypertension. Over the past several years, uncovering the mechanism of immunopathology in schistosomiasis has become a major research objective. It is known that T lymphocytes, especially CD4⁺ T cells, are essential for immune responses against Schistosoma species. However, obtaining a clear understanding of how T lymphocytes regulate the pathological process is proving to be a daunting challenge. To date, CD4⁺ T cell subsets have been classified into several distinct T helper (Th) phenotypes including Th1, Th2, Th17, T follicular helper cells (Tfh), Th9, and regulatory T cells (Tregs). In the case of schistosomiasis, the granulomatous inflammation and the chronic liver pathology are critically regulated by the Th1/Th2 responses. Animal studies suggest that there is a moderate Th1 response to parasite antigens during the acute stage, but then, egg-derived antigens induce a sustained and dominant Th2 response that mediates granuloma formation and liver fibrosis. In addition, the newly discovered Th17 cells also play a critical role in the hepatic immunopathology of schistosomiasis. Within the liver, Tregs are recruited to hepatic granulomas and exert an immunosuppressive role to limit the granulomatous inflammation and fibrosis. Moreover, recent studies have shown that Tfh and Th9 cells might also promote liver granulomas and fibrogenesis in the murine schistosomiasis. Thus, during infection, T-cell subsets undergo complicated cross-talk with antigen presenting cells that then defines their various roles in the local microenvironment for regulating the pathological progression of schistosomiasis. This current review summarizes a vast body of literature to elucidate the contribution of T lymphocytes and their associated cytokines in the immunopathology of schistosomiasis.

Interleukin-9 Aggravates Isoproterenol-Induced Heart Failure by Activating Signal Transducer and Activator of Transcription 3 Signalling

BACKGROUND

Previous studies have demonstrated that inflammation is closely related to the occurrence and development of heart failure (HF). As an inflammation-related cytokine, interleukin (IL)-9 has been reported to be involved in the development of cardiovascular diseases. However, the role of IL-9 in HF in response to isoproterenol (ISO) stimulation has barely been explored. Thus, this study aimed to investigate whether IL-9 participates in HF and the possible associated mechanisms.

METHODS

Chronic ISO infusion was used to establish an HF model, and the IL-9 levels in mice and isolated cardiomyocytes were measured. In addition, ISO-treated mice received an injection of recombinant mouse IL-9 (rIL-9) or an antimouse IL-9 neutralizing monoclonal antibody (mAb) to investigate the effects of IL-9 on cardiac function, hypertrophy, and fibrosis.

RESULTS

IL-9 levels were significantly increased in mice and isolated cardiomyocytes after ISO treatment. Treatment with rIL-9 resulted in aggravated cardiac dysfunction and amplified cardiac hypertrophy and fibrosis, whereas treatment with the anti-IL-9 neutralizing mAb ameliorated cardiac dysfunction and reduced cardiac hypertrophy and fibrosis in ISO-treated mice. In addition, ISO infusion-induced cardiac inflammation and cardiomyocyte apoptosis was aggravated by rIL-9 but prevented by the anti-IL-9 mAb. IL-9 did not activate signal transducer and activator of transcription (STAT)1 or STAT5 but induced STAT3 phosphorylation in ISO-induced HF. Moreover, S31-201, a specific STAT3 inhibitor, nearly abolished rIL-9-induced increases in cardiac dysfunction, hypertrophy, and fibrosis in response to ISO stimulation.

CONCLUSIONS

IL-9 aggravated cardiac dysfunction and amplified cardiac hypertrophy and fibrosis in the ISO-induced HF model by activating STAT3 signalling. These data indicate that blocking IL-9 may be an attractive pharmacotherapeutic strategy for the treatment of cardiac hypertrophy and fibrosis induced by chronic β-adrenergic receptor activation to limit the progression of HF.

Interleukin-9 blockage reduces early hepatic granuloma formation and fibrosis during Schistosoma japonicum infection in mice

Hepatic fibrosis induced by schistosomes is regulated by a complex network of cytokines. T helper type 9 (Th9) cells are a new type of effector T helper cells, which mainly secrete the specific cytokine interleukin-9 (IL-9). Interleukin-9 has been shown to contribute to liver fibrosis in patients with chronic hepatitis B and in a mouse model due to carbon tetrachloride. However, the role of IL-9 in schistosomiasis fibrosis remains unknown. In this study, we investigated the roles of IL-9 in schistosomiasis through in vivo and in vitro studies. The in vivo studies found that neutralization of IL-9 reduced liver granulomatous inflammation and collagen deposition around parasite eggs. The in vitro studies found that the treatment of primary hepatic stellate cells with IL-9 induced a significant increase of collagen and α-smooth-muscle actin. Moreover, we also described the dynamics and relevance of IL-9 and IL-4 in mice infected with Schistosoma japonicum. We found that IL-9 might appear more quickly and at higher levels than IL-4. Hence, our findings indicated that IL-9 might play a role in regulating hepatic fibrosis in early-stage schistosomiasis and become a promising approach for regulating hepatic fibrosis caused by S. japonicum.

Interleukin-9 promotes tumorigenesis through augmenting angiogenesis in non-small cell lung cancer

IL-9 is a proinflammatory cytokine that plays a critical role in autoimmunity and inflammatory diseases. However, its role in tumorigenesis has not been well studied. In this study, we found that IL-9 expression was significantly increased and associated with poor progression in human non-small cell lung cancer (NSCLC). Ectopic expression of IL-9 in NSCLC cells did not affect cell proliferation and apoptosis in vitro, but markedly promoted tumor growth in vivo. Immune-profile analysis showed no significant changes in the frequencies of infiltrated immune cells in the tumor site, neither in nude mice nor in immune-competent mice. However, we found that VEGF and microvessel density (MVD) were significantly increased in xenografts. IL-9 could promote cell growth and tube formation of HUVEC cells in vitro. In addition, correlation analysis implied a significant positive relationship between the density of IL-9 and VEGF, as well as MVD in human NSCLC tissues. Finally, we found that IL-9 stimulated tumor angiogenesis via STAT3 signaling. Together, our findings demonstrate a promoting role of IL-9 in lung cancer development, probably through promoting tumor angiogenesis. IL-9 thus may represent a new prognostic marker and therapeutic target for NSCLC.

Skin-homing T-cell responses associated with Demodex infestation and rosacea

AIMS

Our aim was to investigate the skin-homing T-cell immune responses triggered in patients with Demodex infestation and/or rosacea.

METHODS

Collected whole blood samples were divided into four groups: control subjects; nonrosacea patients with Demodex infestation (Demodex group); papulopustular rosacea (PPR) patients without Demodex infestation (Rosacea group); and PPR patients with Demodex infestation (Rosacea/Demodex group). Following ex vivo activation, skin-homing CLA+CD4+ T-cell subset levels were monitored by flow cytometry.

RESULTS

When compared with control subjects, among skin-homing CD4+ T-cell subsets analysed, Demodex patients had higher T_H 9 and T_reg cell levels; Rosacea subjects displayed elevated T_H 1 cell levels; and Rosacea/Demodex patients exhibited increased frequencies of T_H 9 and T_H 22 cells. In contrast to Rosacea subjects, Rosacea/Demodex group members displayed higher T_H 2 cell levels; and when compared with Demodex groups, they had higher T_H 1 and T_H 2 but lower T_reg cell levels. Demodex group members also exhibited higher T_reg but lower T_H 1 and T_H 22 levels than Rosacea/Demodex group subjects.

CONCLUSIONS

The skin-homing T-cell responses associated with Demodex infestation and rosacea formation seem to influence each other. The present as well as future studies could contribute to the development of effective treatment strategies for demodicosis and rosacea.

Th 9 cells in Behçet disease: Possible involvement of IL-9 in pulmonary manifestations

Behçet disease (BD) is a multisystemic disease some of whose manifestations are characterized by pulmonary involvements. The purpose of the study was to evaluate the level of T-helper type 9 (Th9) cells and the cytokine interleukin (IL)-9 in peripheral blood and in bronchoalveolar lavage (BAL) of patients with Behçet's disease (BD) affected by pulmonary manifestations. Nevertheless, until recently there have been no studies on its role in BD. The Th9 (CD4⁺IL-9⁺T) cell, transcription factor PU.1 and IL-9 mRNA levels, as well as serum and BAL IL-9 concentration, were measured in BD patients and healthy controls. The Th9 cell percentage and absolute number, PU.1 and IL-9 expression levels of BD patients were all increased significantly compared with the control group. Absolute number of Th9 cells was particularly increased in patients with active BD compared to inactive BD patients. The levels of IL-9 associated to Th9 expression depended on BD severity. These parameters were markedly expressed in the BAL of BD patients with pulmonary manifestations. IL-17 and the epithelial inflammatory cytokine TSLP were significantly correlated to IL-9 levels. This cytokine trio decreased in inactive BD patients after corticosteroïd treatment. In addition, IL-9 levels were correlated to CD4⁺ IL-9⁺ cells in BAL and in PBMCs. LPS stimulated PBMCs and macrophages induced increased secretion of IL-9 and the encoding transcription factors PU.1 and IRF4. 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 BD, which may be supported by the increased release of IL-17 and TSLP. We provide evidence that Th9 T cells are increased in BD patients with pulmonary manifestations. This suggests an important role of IL-9 in the pathogenesis of BD particularly in patients suffering from lung involvement.

Features and roles of T helper 9 cells and interleukin 9 in immunological diseases

T helper 9 (T_H9) cells are considered as newly classified helper T cells that have an important role in the regulation of immune responses. Since these cells preferentially produce IL-9, these cells are termed T_H9 cells. Recently, the role of T_H9 and its signature cytokine (IL-9) has been investigated in a wide range of diseases, including autoimmunity, allergy, infections, cancer and immunodeficiency. Herein, we review the most recent data concerning T_H9 cells and IL-9 as well as their roles in disease. These insights suggest that T_H9 cells are a future target for therapeutic intervention.

Characterization and allergic role of IL-33-induced neutrophil polarization

Neutrophils are involved in the pathogenesis of allergy. However, the contribution of the different functionally polarized neutrophils in allergy needs to be clarified. We sought to define the characteristics of interleukin (IL)-33-induced neutrophils and the involvement of this subset of polarized neutrophils in allergic pathogenesis. Freshly isolated neutrophils were treated with different cytokines and the cytokine expression levels were detected by real-time PCR. The gene expression profile of IL-33-induced neutrophils was determined by microarray assay. Adoptive transfer assay was used to investigate the function of IL-33-induced neutrophils in an ovalbumin (OVA)-induced allergic asthma model. IL-33-treated neutrophils selectively produced IL-4, IL-5, IL-9 and IL-13 (referred as to N(IL-33) cells) and displayed a distinctive gene expression profile in sharp contrast to resting and lipopolysaccharide (LPS)-treated neutrophils. IL-33-induced neutrophils expressed high Levels of IL-1R2 on cell surface, whereas resting and LPS-treated neutrophils did not, indicating IL-1R2 might be used as a biomarker for N(IL-33) cells. Importantly, N(IL-33) neutrophils exist in the lungs of OVA-induced allergic asthma mice. Adoptive transfer of N(IL-33) neutrophils significantly promotes the severity of the lung pathogenesis in this model. IL-33 induces neutrophil polarization through c-Jun N-terminal kinase- and nuclear factor-κB-dependent pathways. A previously unappreciated neutrophil polarization driven by IL-33 with unique cell surface markers and cytokine/chemokine-producing gene profile was defined. The newly identified N(IL-33) subpopulation may have significant contribution to IL-33-related pathogenesis.

Exogenous IL-9 Ameliorates Experimental Autoimmune Myasthenia Gravis Symptoms in Rats

Interleukin-9 (IL-9) is a multifunctional cytokine involved in protective immunity or immunopathology depending on the microenvironment and specific disease settings. Our early study determined that IL-9 and Th9 cells participate in and promote the progression of experimental autoimmune myasthenia gravis (EAMG). The data from this study showed that exogenous recombinant rat IL-9 (rrIL-9) acted as an IL-9 receptor antagonist, reduced the incidence of EAMG in rats, alleviated the severity of the disease, and reduced the anti-acetylcholine receptor (AChR) IgG antibody levels by altering the Th-subset distribution. These data suggest that administration of rrIL-9 may provide a novel therapeutic strategy against MG or related autoimmune diseases. Abbreviations: 2-Mercaptoethanol (2-ME); antibodies (Abs); ?-bungarotoxin (?-BTX); acetylcholine receptor (AChR); airway hyper-reactivity (AHR); allophycocyanin-conjugated (APC); antigen presenting cells (APCs); complete Freund's adjuvant (CFA); Cyanine dye 3 (Cy3); dendritic cells (DCs); experimental autoimmune encephalomyelitis (EAE); experimental autoimmune myasthenia gravis (EAMG); flow cytometry (FACS); fetal bovine serum (FBS); fetal calf serum (FCS); Fluorescein isothiocyanate (FITC); gamma chain (?c); intraperitoneally (i.p.); Incomplete Freund's adjuvant (IFA); interferon (IFN); immunoglobulin (Ig); Interleukin (IL); Janus kinase (JAK); myasthenia gravis (MG); Mononuclear cells (MNC); neuromuscular junctions (NMJ); optical density (OD); ovalbumin (OVA); phosphate-buffered saline (PBS); phycoerythrin (PE); Peridinin chlorophyll protein complex (Percp); Rat AChR ? subunit (R-AChR97-116); Recombinant Rat (rr); room temperature (RT); signal transducer and activator of transcription (STAT); T helper cells (Th).

Th9 Cells: Probable players in ulcerative colitis pathogenesis

T lymphocytes represent an important part of adaptive immune system undertaking different functions to regulate immune responses. CD4+ T cells are the most important activator cells in inflammatory conditions. Depending on the type of induced cells and inflamed sites, expression and activity of different subtypes of helper T cells are changed. Recent studies have confirmed the existence of a new subset of helper T lymphocytes called Th9. Naive T cells can differentiate into Th9 subtypes if they are exposed simultaneously by interleukin (IL) 4 and transforming growth factor β and also secondary activation of a complicated network of transcription factors such as interferon regulatory factor 4 (IRF4) and Smads which are essential for adequate induction of this phenotype. Th9 cells specifically produce interleukin 9 and their probable roles in promoting intestinal inflammation are being investigated in human subjects and experimental models of ulcerative colitis (UC). Recently, infiltration of Th9 cells, overexpression of IL-9, and certain genes associated with Th9 differentiation have been demonstrated in inflammatory microenvironment of UC. Intestinal oversecretion of IL-9 protein is likely to break down epithelial barriers and compromise tolerance to certain commensal microorganisms which leads to inflammation. Th9 pathogenicity has not yet been adequately explored in UC and they are far from being considered as inflammatory cells in this milieu, therefore precise understanding the role of these newly identified cells in particular their potential role in gut pathogenesis may enable us to develop novel therapeutic approaches for inflammatory bowel disease. So, this article tries to discuss the latest knowledge on the above-mentioned field.

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.

Guidance of super-enhancers in regulation of IL-9 induction and airway inflammation

Xiao et al. demonstrate that formation of super-enhancers at Il9 locus is critical for robust IL-9 expression and Th9 cell induction, and assembly of Il9 super-enhancers is driven by OX40-mediated chromatin acetylation.

Th9 cells are prominently featured in allergic lung inflammation, but the mechanism that regulates IL-9 induction in T helper cells remains poorly defined. Here we demonstrate that formation of super-enhancers (SEs) is critical in robust induction of IL-9 and that assembly of the Il9 SEs in Th cells requires OX40-triggered chromatin acetylation. Mechanistically, we found that OX40 costimulation induces RelB expression, which recruits the histone acetyltransferase p300 to the Il9 locus to catalyze H3K27 acetylation. This allows binding of the SE factor Brd4 to organize assembly of the SE complex, which in turn drives robust IL-9 expression and Th9 cell induction. Thus, Th9 cells are strongly induced upon OX40 stimulation, and disruption of SEs abolished Th9 cell induction in vitro and inhibited Th9 cell–mediated allergic airway inflammation in vivo. Together, our data suggest that formation of SEs is essential in IL-9 expression and Th9 cell induction. These findings may have important clinical implications.

Levels of cytokines in drug hypersensitivity

Introduction

Multiple drug intolerance is a serious complication of drug therapy and is an issue of allergology. The aim of the study was the investigation of cytokine status in patients with drug hypersensitivity and multiple drug hypersensitivity.

Material and methods

19 patients with multiple drug hypersensitivity, 34 patients with hypersensitivity to one drug, and 35 non-allergic subjects were involved. Only women were included in the study. A multiplex assay of 27 cytokines and chemokines was performed using xMap technology (Human Cytokine Panel I by Bio-Rad).

Results

Women with drug allergy revealed increased IL-2 levels (p < 0.05). In the case of the study of cytokine status in patients with multiple drug hypersensitivity, the new data revealed the prevalence of pro-inflammatory cytokine status with the participation of cytokines IL-17, IL-9, TNF-α, IP-10, and MIP-1.

Conclusions

Various immune response arms Th2, Th17, as well as macrophages were the determining factors in the cytokine balance that was found in patients with multiple drug hypersensitivity.

Interleukin-9 over-expression and T helper 9 polarization in systemic sclerosis patients

T helper 9 (Th9) cells and interleukin (IL)-9 are involved in the pathogenesis of several autoimmune diseases. The exact role of IL-9 and Th9 cells in patients with systemic sclerosis (SSc) have not yet been studied adequately. IL-9, IL-9R, transcription factor PU.1 (PU.1), IL-4, thymic stromal lymphopoietin (TSLP) and transforming growth factor (TGF)-β expression were assessed in skin and kidney biopsies of SSc patients and healthy controls (HC) by immunohistochemistry (IHC). The cellular source of IL-9 was also analysed by confocal microscopy analysis. Peripheral IL-9-producing cells were also studied by flow cytometry. The functional relevance of IL-9 increased expression in SSc was also investigated. Our results demonstrated a strong expression of IL-9, IL-9R, IL-4, TSLP and TGF-β in skin tissues of patients with both limited and diffuse SSc. IL-9 expression was observed mainly in the context of skin infiltrating mononuclear cells and keratinizing squamous epithelium. IL-9 over-expression was also observed in renal biopsies of patients with SSc. IL-9 producing cells in the skin were identified as Th9 cells. Similarly, Th9 cells were expanded and were the major source of IL-9 among SSc peripheral blood mononuclear cells (PBMC), their percentage being correlated directly with the modified Rodnan skin score. Infiltrating mononuclear cells, mast cells and neutrophils expressed IL-9R. In in-vitro studies stimulation with rIL-9 significantly induced NET (neutrophil extracellular traps) release by dying cells (NETosis) in neutrophils, expansion of mast cells and increase of anti-systemic scleroderma 70 (Scl70) production by B cells. Our findings suggest that Th9 cells and IL-9 could be implicated in the pathogenesis of SSc.

Detection of IL-9 producing T cells in the PBMCs of allergic asthmatic patients

BACKGROUND

Interleukin-9 (IL-9) was reported as an active participant in the pathogenesis of allergic asthma. This study aimed to investigate the major source ofIL-9 and its effect on interferon γ (IFN-γ) and immunoglobulin (Ig) secretion by B cells.

METHODS

We isolated peripheral blood mononuclear cells from children with allergic asthma and healthy children. IL-9, IL-4 and IFN-γ expression were detected by ELISA, ELISpot and Flowcytometry. Expression of transcription factor PU.1 was measured by Western Blot. We evaluated the effect of IL-9 on B cell activation and Ig production.

RESULTS

Results showed that compared with healthy children, levels of IL-9, IL-4 and PU.1 were elevated and levels of IFN-γ were lower in children with allergic asthma. IL-9-expressing CD4⁺ T cells did not co-express IL-4. Exogenous IL-9 inhibited IFN-γ production in a dose-dependent manner. Antigen-specific Th9 cells existed in children with house dust mite allergic asthma. IL-9 up-regulated expression of CD69 and CD25 on B cells and combination of IL-9 and IL-4 enhanced IgE production.

CONCLUSIONS

In conclusion, our results showed that Th9 cells may be the major source of IL-9 in children with allergic asthma. In these patients, IL-9 impairs IFN-γ production and synergistically promotes IL-4-induced IgE secretion.

IL-9 and Th9 cells in health and diseases-From tolerance to immunopathology

CD4+ T cells have the capacity to differentiate into various T helper (Th) cell subsets after activation, and by acquiring distinct cytokine profiles and effector functions, they regulate the nature as well as the outcomes of immune responses. Th9 cells are a relatively new member in the Th cell family. The signature cytokine for Th9 cells is IL-9, a cytokine in the IL-2Rγc-chain family. Over the past few years, there has been an explosion of knowledge on the roles of Th9 cells in immunity and immunopathology, but the exact mechanisms in the control of Th9 cells remain poorly defined. This apparent paradox presents both challenges and opportunities. Here we review recent advances in our understanding of the fundamental biology of IL-9 and Th9 cells, highlighting the challenges and unanswered questions in the field. We also discuss potential opportunities in targeting Th9 cells for therapeutic purposes in the clinic.

Dynamics of Th9 cells and their potential role in immunopathogenesis of murine schistosomiasis

Background

Th1, Th2, Th17, Treg and Tfh cells play important roles in schistosomiasis. Th9 cells secrete IL-9 as a signature cytokine and contribute to several classes of inflammatory disease. However, the effects of Th9 cells in schistosomiasis are unknown. We aimed to explore the dynamic changes and potential roles of Th9 cells in the pathogenesis of hepatic egg granulomatous inflammation in mice infected with Schistosoma japonicum.

Methods

Twenty mice with S. japonicum infection and five normal controls (NC) were used as models. The average areas of egg granulomas were estimated by hematoxylin-eosin (H & E) staining. Hepatic IL-9 and transcription factor PU.1 levels were detected by immunohistochemistry. Flow cytometry techniques were used to analyze the proportions of Th9 cells. With the help of ELISA, serum levels of IL-9 were examined.

Results

The egg granulomas began to form from four weeks after infection and continued to develop. In parallel with the development of egg granulomas, the hepatic levels of IL-9 and PU.1 increased very slowly during the first four weeks post-infection and increased rapidly thereafter. Moreover, the proportions of splenic Th9 cells and levels of serum IL-9 had similar developmental trends with the egg granulomas.

Conclusion

The proliferation of Th9 cells and levels of IL-9 were significantly higher in S. japonicum-infected mice compared to NC. In addition, dynamic changes of Th9 and IL-9 were synchronous with the developmental trend of hepatic egg granulomatous inflammation, suggesting that Th9 cells might be a new subset in the pathogenesis of schistosomiasis.

Overexpression and varied clinical significance of Th9 versus Th17 cells in distinct subtypes of oral lichen planus

OBJECTIVE

Oral lichen planus (OLP) presents with large numbers of T lymphocytes accumulating beneath the epithelium of the oral mucosa; however, its aetiology remains obscure. A potential role for an emerging novel T cell subset, Th9, in OLP has recently been suggested but remains to be clarified. The current aim was to investigate the expression and potential clinical significance of Th9 cells in distinct subtypes of OLP.

MATERIALS AND METHODS

Peripheral blood samples were collected from 41 OLP patients and 18 healthy controls (HCs). Flow cytometric analysis was used to detect the CD4+ T helper subset Th9 (IL-9⁺IL-17^-CD4⁺ Th cells) and Th17 (IL-9^-IL-17⁺CD4⁺ Th cells) expression levels.

RESULTS

Flow cytometry results showed significantly elevated levels of Th9 cells in reticular and erosive OLP compared to HCs. Th9 expression in erosive OLP was less than in reticular OLP, indicating that Th9 but not Th17 cells may play a predominant role in reticular disease. However, in erosive OLP patients, we found much higher levels of Th17 cells compared to reticular OLP patients and HCs, indicating that Th17 dominates in erosive OLP. Statistical analysis showed positive correlations of Th9 cells and Th17 cells in patients with reticular or erosive OLP but none in HCs.

CONCLUSIONS

Th9 and Th17 cells may take the predominant roles in reticular and erosive OLP respectively, and their numbers were positively correlated in reticular and erosive OLP patients. Elevated circulating Th9 cells may help maintain immune balance in OLP immunopathogenesis, which requires further investigation.

Melatonin signaling in T cells: Functions and applications

Melatonin affects a variety of physiological processes including circadian rhythms, cellular redox status, and immune function. Importantly, melatonin significantly influences T-cell-mediated immune responses, which are crucial to protect mammals against cancers and infections, but are associated with pathogenesis of many autoimmune diseases. This review focuses on our current understanding of the significance of melatonin in T-cell biology and the beneficial effects of melatonin in T-cell response-based diseases. In addition to expressing both membrane and nuclear receptors for melatonin, T cells have the four enzymes required for the synthesis of melatonin and produce high levels of melatonin. Meanwhile, melatonin is highly effective in modulating T-cell activation and differentiation, especially for Th17 and Treg cells, and also memory T cells. Mechanistically, the influence of melatonin in T-cell biology is associated with membrane and nuclear receptors as well as receptor-independent pathways, for example, via calcineurin. Several cell signaling pathways, including ERK1/2-C/EBPα, are involved in the regulatory roles of melatonin in T-cell biology. Through modulation in T-cell responses, melatonin exerts beneficial effects in various inflammatory diseases, such as type 1 diabetes, systemic lupus erythematosus, and multiple sclerosis. These findings highlight the importance of melatonin signaling in T-cell fate determination, and T cell-based immune pathologies.

T Cells in Osteoarthritis: Alterations and Beyond

Although osteoarthritis (OA) has been traditionally regarded as a non-inflammatory disease, reports increasingly suggest that it is inflammatory, at least in certain patients. OA patients often exhibit inflammatory infiltration of synovial membranes by macrophages, T cells, mast cells, B cells, plasma cells, natural killer cells, dendritic cells, granulocytes, etc. Although previous reviews have summarized the knowledge of inflammation in the pathogenesis of OA, as far as we know, no report review our current understanding about T cells, especially, each T cell subtype, in the biology of OA. This review highlights the current understanding of the role of T cells in the pathogenesis of OA, with attention to Th1 cells, Th2 cells, Th9 cells, Th17 cells, Th22 cells, regulatory T cells, follicular helper T cells, cytotoxic T cells, T memory cells, and even unconventional T cells (e.g., γδ T cells and cluster of differentiation 1 restricted T cells). The findings highlight the importance of T cells to the development and progression of OA and suggest new therapeutic approaches for OA patients based on the manipulation of T-cell responses.

Amino-acid transporters in T-cell activation and differentiation

T-cell-mediated immune responses aim to protect mammals against cancers and infections, and are also involved in the pathogenesis of various inflammatory or autoimmune diseases. Cellular uptake and the utilization of nutrients is closely related to the T-cell fate decision and function. Research in this area has yielded surprising findings in the importance of amino-acid transporters for T-cell development, homeostasis, activation, differentiation and memory. In this review, we present current information on amino-acid transporters, such as LAT1 (l-leucine transporter), ASCT2 (l-glutamine transporter) and GAT-1 (γ-aminobutyric acid transporter-1), which are critically important for mediating peripheral naive T-cell homeostasis, activation and differentiation, especially for Th1 and Th17 cells, and even memory T cells. Mechanically, the influence of amino-acid transporters on T-cell fate decision may largely depend on the mechanistic target of rapamycin complex 1 (mTORC1) signaling. These discoveries remarkably demonstrate the role of amino-acid transporters in T-cell fate determination, and strongly indicate that manipulation of the amino-acid transporter-mTORC1 axis could ameliorate many inflammatory or autoimmune diseases associated with T-cell-based immune responses.

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.

Cytokine profile and maternal depression and anxiety symptoms in mid-pregnancy-the FinnBrain Birth Cohort Study

Maternal prenatal psychological symptoms are associated with child health outcomes, e.g., atopic diseases. Altered prenatal functioning of the immune system is a potential mechanism linking maternal symptoms with child health. Research on prenatal distress and cytokines is warranted. The study population comprised consecutive N = 139 women from a general population-based FinnBrain Birth Cohort Study. Standardized questionnaires for depressive, overall anxiety, and pregnancy-related anxiety symptoms were used. Serum concentrations of selected cytokines were analyzed using Multiplex bead arrays from samples drawn at the gestational week 24. The concentrations of T helper (Th)2-related interleukins (IL)-9 and IL-13 and Th1-related IL-12 correlated positively with prenatal depressive and overall anxiety symptom scores (p values, range 0.011-0.029). Higher interferon (IFN)-γ/IL-4 ratio (p = 0.039) and Th2-related IL-5 (p = 0.007) concentration correlated positively with depressive symptoms. Pregnancy-related anxiety score correlated positively with IL-12 (p = 0.041), IL-13 (p = 0.025), and anti-inflammatory IL-10 (p = 0.048) concentrations. IL-6 and TNF-α concentrations were unrelated to prenatal symptoms. As a novel finding, we observed positive correlations between concentrations of potentially proallergenic cytokines and maternal prenatal psychological symptoms. Different symptom measures may yield distinct cytokine responses. This provides hypotheses for studies on mechanisms bridging prenatal stress and child health.

Th9 cytokines response and its possible implications in the immunopathogenesis of leprosy

AIMS

Leprosy is an infectious-contagious disease whose clinical evolution depends on the interaction of the infectious agent with the immune response of the host, leading to a clinical spectrum that ranges from lepromatous leprosy (susceptibility, LL) to tuberculoid leprosy (resistance, TT). The immune response profile will depend on the pattern of cytokine production and on the activity of macrophages during infection. Classically, the clinical evolution of leprosy has been associated with Th1/Th2 cytokine profiles, but the role of new cytokine profiles such as T helper 9 (Th9) remains to be elucidated.

METHODS

To evaluate the tissue expression profile of these cytokines, a cross-sectional study was conducted using a sample of 30 leprosy skin lesion biopsies obtained from patients with leprosy, 16 TT and 14 lepromatous LL.

RESULTS

Immunohistochemical analysis revealed a significant difference in interleukin (IL)-9, IL-4 transforming growth factor (TGF)-β and IL-10 levels between the two groups. IL-9 was more expressed in TT lesions compared with LL lesions. Higher expression of IL-4, IL-10 and TGF-β was observed in LL compared with TT. IL-4, IL-10 and TGF-β tended to be negatively correlated with the expression of IL-9, indicating a possible antagonistic activity in tissue.

CONCLUSIONS

The results suggest that Th9 lymphocytes may be involved in the response to Mycobacterium leprae, positively or negatively regulating microbicidal activity of the local immune system in the disease.

Serum Interleukin (IL)-9 and IL-10, but not T-Helper 9 (Th9) Cells, are Associated With Survival of Patients With Acute-on-Chronic Hepatitis B Liver Failure

CD4 T helper (Th) cells are reported to be essential for initiating and maintaining an effective immune response to hepatitis B virus (HBV) infection. Th9 cells are a new subset of CD4 Th cells that produce interleukin (IL)-9 and IL-10. The present study aimed to investigate the percentage of Th9 cells relative to the number of CD4 cells in peripheral blood. We also measured serum IL-9 and IL-10 levels in different stages of HBV infection and their relationship with progress and prognosis of liver disease. Whole blood samples from 111 patients with HBV infection, including 39 chronic hepatitis B (CHB), 25 HBV-liver cirrhosis (HBV-LC), 21 acute-on-chronic liver failure (ACLF) patients, and 26 healthy controls were collected. The percentage of Th9 cells and serum IL-9 and IL-10 levels were determined. There was no significant difference in the percentage of Th9 cells and serum IL-9 and IL-10 levels among different groups, nor were these related to hepatitis B e antigen status, complications of cirrhosis, inflammation index, or prognosis indexes. There was no change in the percentage of Th9 cells before and after antiviral treatment in CHB patients. There was no correlation of Th9 cells with survival of ACLF patients. However, IL-9 and IL-10 levels were significantly higher in the nonsurvived ACLF patients compared to survived ACLF patients. Furthermore, baseline IL-9 level predicted the prognosis of ACLF patients with 87.5% sensitivity and 61.5% specificity.Thus, our data indicate that Th9 cells were unlikely involved in the pathogenesis of HBV infection, but elevation in IL-9 and IL-10 may signal poor prognosis for ACLF.

Interleukin-9 and interleukin-17C in chronic rhinosinusitis

BACKGROUND

Interleukin (IL)-9 and IL-17C have been known to play a role in allergic inflammation, yet, their roles in chronic rhinosinusitis (CRS) are not well defined. IL-9 induces changes in epithelial cell gene expression leading to goblet cell metaplasia, whereas IL-17C is functionally distinct in that its expression can be induced by bacterial challenge and inflammatory stimuli. This study aimed to compare levels of IL-9 and IL-17C in CRS with nasal polyps (CRSwNP) and without nasal polyps (CRSsNP) as well as atopy.

METHODS

Nasal polyp or sinus mucosal specimens from CRSwNP (n = 36), CRSsNP (n = 9), and control (n = 9) groups were collected and processed. Patient atopy status was determined by history of skin-prick test and pulmonary function test. Immunohistochemistry was carried out using anti-human IL-9 and IL-17C antibodies. Positively-stained cells were enumerated under high-power (×400) magnification in 5 consecutive fields.

RESULTS

The level of expression of IL-9 was higher in CRSwNP than CRSsNP and control. Similar findings were demonstrated in IL-17C with higher expression in CRSwNP than CRSsNP and control. Both the averages of positively-stained cells expressing IL-9 and IL-17C were higher in CRS with asthma and allergy compared to control. This suggested that IL-9 and IL-17C were both involved in the pathogenesis of CRS, allergy, and asthma.

CONCLUSION

Inflammatory cell expression of IL-9 and IL-17C were increased in CRS, particularly with allergy and asthma. These interleukins may contribute to the pathogenesis of CRSwNP as well as atopy and may serve as therapeutic targets for disease management.

Innate immunity underlies symbiotic relationships

Here, the modern data regarding interactions between normal microbiota and barrier tissues in plants, humans and animals are reviewed. The main homeostatic mechanisms responsible for interactions between epithelium and innate immune cells with symbiotic bacteria are described. A key step in this process is recognition of soluble microbial products by ligation to pattern-recognition receptors expressed on the host cells. As a result, epithelial cells secrete mucus, antibacterial peptides and immunoregulatory molecules. The main outcomes from immunological reactions towards symbiotic bacteria involve development of conditions for formation and maintenance of microbial biocenosis as well as providing safety for the host. Also, it is considered important to preserve and transfer beneficial bacteria to progeny.

p-STAT6, PU.1, and NF-κB are involved in allergen-induced late-phase airway inflammation in asthma patients

Background

Previous in vitro and animal studies demonstrated that transcription factors p-STAT6 and PU.1 are required to induce interleukin (IL)-9 secretion by T helper (Th) 9 cells. It is believed that n factor-kappaB (NF-κB) plays a role in eosinophil survival. The importance of these transcription factors in the pathogenesis of allergic asthma (AA) in humans is poorly understood. We evaluated p-STAT6 and PU.1 expression in peripheral blood Th9 cells and NF-κB expression in eosinophils during late-phase airway inflammation in AA patients.

Methods

Nineteen adults with AA and 14 adult healthy individuals (HI) were examined. Peripheral blood collected 24 h before (baseline) and 24 h after bronchial allergen challenge. CD4⁺ cells and eosinophils were isolated by high-density gradient centrifugation and magnetic separation. The percentage of Th9 cells and apoptotic eosinophils was estimated by flow cytometry. p-STAT6 and PU.1 expression was expressed as mean fluorescence intensity (MFI) in Th9 cells. NF-κB levels were expressed as MFI in peripheral blood eosinophils. Serum IL-9 and IL-5 levels were determined by enzyme-linked immunosorbent assay.

Results

At baseline, MFI of p-STAT6 and PU.1 in peripheral blood Th9 cells and MFI of NF-κB in eosinophils and, serum IL-5 and IL-9 levels were greater in AA patients (P < 0.05). Decreased eosinophil apoptosis was seen in the AA group compared with HI (P < 0.05). MFI of p-STAT6, PU.1, and NF-κB and serum levels of IL-5 and IL-9 were increased in the AA group 24 h after challenge compared with baseline (P < 0.05). In the AA group, a correlation between serum IL-9 and Th9 cells (r = 0.7, P = 0.001) and MFI of PU.1 (r = 0.6, P = 0.01) 24 h after bronchial allergen challenge was observed. A correlation between Th9 cells and MFI of p-STAT6 (r = 0.45, P = 0.03) as well as MFI of PU.1 (r = 0.5, P = 0.02) 24 h after challenge was only observed in AA patients. A correlation between the MFI of NF-κB and eosinophil apoptosis was observed in AA patients 24 h before (r = −0.46, P = 0.02) and after (r = −0.5, P = 0.02) challenge.

Discussions

p-STAT6 and PU.1 may be associated with Th9 cells and IL-9 production, whereas NF-κB and IL-5 may be associated with reduced eosinophil apoptosis in allergen-induced late-phase airway inflammation.

Trial registration

ClinicalTrials.gov NCT02214303

Electronic supplementary material

The online version of this article (doi:10.1186/s12890-015-0119-7) contains supplementary material, which is available to authorized users.

GITR subverts Foxp3(+) Tregs to boost Th9 immunity through regulation of histone acetylation

Glucocorticoid-induced TNFR-related protein (GITR) is a costimulatory molecule with diverse effects on effector T cells and regulatory T cells (Tregs), but the underlying mechanism remains poorly defined. Here we demonstrate that GITR ligation subverts the induction of Foxp3⁺ Tregs and directs the activated CD4⁺ T cells to Th9 cells. Such GITR-mediated iTreg to Th9 induction enhances anti-tumour immunity in vivo. Mechanistically, GITR upregulates the NF-κB family member p50, which recruits histone deacetylases to the Foxp3 locus to produce a ‘closed' chromatin structure. Furthermore, GITR ligation also activates STAT6, and STAT6 renders Il9 locus accessible via recruitment of histone acetyltransferase p300, and together with inhibition of Foxp3, GITR induces strong Th9 responses. Thus, Th9 cells and iTregs are developmentally linked and GITR can subvert tolerogenic conditions to boost Th9 immunity.

Glucocorticoid-induced TNFR-related protein (GITR), a costimulatory protein expressed by T cells, has immunostimulatory effect but the underlying mechanism is not clear. Here the authors show that GITR ligation inhibits the induction of Foxp3 expression and diverts CD4 T cells towards Th9 differentiation instead of iTreg.

Treatment of severe asthma: entering the era of targeted therapy

INTRODUCTION

It is estimated that 5 - 10% of asthma patients suffer from severe asthma. Severe asthma is associated with increased morbidity and mortality. These patients are not controlled with currently available treatments and therefore additional treatment options are needed. Asthma is a heterogeneous disease, and different asthma patient groups probably have different underlying pathophysiology. Novel therapies with, for example, monoclonal antibodies that target certain immunological pathways have become available. These novel treatments are not effective in all patients but only in certain phenotypes.

AREAS COVERED

This review covers the current evidence and novel developments in treatment with monoclonal antibodies in different asthma phenotypes. This includes monoclonal antibodies against IgE, against interleukin (IL)-5 and antibodies targeting IL-13 pathways. Although there is a certain overlap between patient groups benefiting from these treatments, a more detailed identification of responder profiles for these therapies is needed for personalized therapy.

EXPERT OPINION

In recent years, novel monoclonal antibodies have been developed, which are a promising addition to existing therapy in the treatment of severe asthma with eosinophilic inflammation and Th2-driven disease. We expect that several of the new antibodies will become available for clinical practice. In addition, it must be acknowledged that so far no effective strategies are available for patients with non-eosinophilic asthma and further research and development is necessary for this patient group.