Interleukin-9 promotes mast cell progenitor proliferation and CCR2-dependent mast cell migration in allergic airway inflammation

Allergic asthma is a chronic lung disease characterized by airway hyperresponsiveness and cellular infiltration that is exacerbated by immunoglobulin E-dependent mast cell (MC) activation. Interleukin-9 (IL-9) promotes MC expansion during allergic inflammation but precisely how IL-9 expands tissue MCs and promotes MC function is unclear. In this report, using multiple models of allergic airway inflammation, we show that both mature MCs (mMCs) and MC progenitors (MCp) express IL-9R and respond to IL-9 during allergic inflammation. IL-9 acts on MCp in the bone marrow and lungs to enhance proliferative capacity. Furthermore, IL-9 in the lung stimulates the mobilization of CCR2+ mMC from the bone marrow and recruitment to the allergic lung. Mixed bone marrow chimeras demonstrate that these are intrinsic effects in the MCp and mMC populations. IL-9-producing T cells are both necessary and sufficient to increase MC numbers in the lung in the context of allergic inflammation. Importantly, T cell IL-9-mediated MC expansion is required for the development of antigen-induced and MC-dependent airway hyperreactivity. Collectively, these data demonstrate that T cell IL-9 induces lung MC expansion and migration by direct effects on the proliferation of MCp and the migration of mMC to mediate airway hyperreactivity.

Mechanistic insight of interleukin-9 induced osteoclastogenesis

Interleukin (IL)-9 is an emerging player in the pathogenesis of various chronic inflammatory diseases including bone disorders like rheumatoid arthritis (RA) and psoriatic arthritis. Recently, IL-9 was shown to enhance the osteoclast formation and their function in RA. However, the mechanisms by which IL-9 influences osteoclastogenesis are not known. Therefore, in this study we aimed to unravel the direct and indirect ways by which IL-9 can influence osteoclast formation. We used mouse bone marrow precursor cells for checking the effect of IL-9 on osteoclast differentiation and its function. Next, IL-9 induced signalling pathway were checked in the process of osteoclastogenesis. T cells play an important role in enhancing osteoclastogenesis in inflammatory conditions. We used splenic T cells to understand the impact of IL-9 on the functions of T effector (Teff) and regulatory T (Treg) cells. Furthermore, the effect of IL-9 mediated modulation of the T cell response on osteoclasts was checked using a coculture model of T cells with osteoclast precursors. We showed that IL-9 enhanced osteoclast formation and its function. We found that IL-9 activates STAT3, P38 MAPK, ERK1/2, NFκB and we hypothesize that it mediates the effect on osteoclastogenesis by accelerating mitochondrial biogenesis. Additionally, IL-9 was observed to facilitate the functions of pro-osteoclastogenic IL-17 producing T cells, but inhibits the function of anti-osteoclastogenic Treg cells. Our observations suggest that IL-9 can influence osteoclastogenesis directly by modulating the signalling cascade in the precursor cells; indirectly by enhancing IL-17 producing T cells and by reducing the functions of Treg cells.

Mass cytometry analysis identifies T cell immune signature of aplastic anemia and predicts the response to cyclosporine

Aplastic anemia (AA) is an auto-activated T cell-mediated bone marrow failure. Cyclosporine is often used to treat non-severe AA, which demonstrates a more heterogeneous condition than severe AA. The response rate to cyclosporine is only around 50% in non-severe AA. To better predict response to cyclosporine and pinpoint who is the appropriate candidate for cyclosporine, we performed phenotypic and functional T cell immune signature at single cell level by mass cytometry from 30 patients with non-severe AA. Unexpectedly, non-significant differences of T cell subsets were observed between AA and healthy control or cyclosporine-responder and non-responders. Interestingly, when screening the expression of co-inhibitory molecules, T cell trafficking mediators, and cytokines, we found an increase of cytotoxic T lymphocyte antigen 4 (CTLA-4) on T cells in response to cyclosporine and a lower level of CTLA-4 on CD8⁺ T cells was correlated to hematologic response. Moreover, a decreased expression of sphingosine-1-phosphate receptor 1 (S1P₁) on naive T cells and a lower level of interleukin-9 (IL-9) on T helpers also predicted a better response to cyclosporine, respectively. Therefore, the T cell immune signature, especially in CTAL-4, S1P₁, and IL-9, has a predictive value for response to cyclosporine. Collectively, our study implies that immune signature analysis of T cell by mass cytometry is a useful tool to make a strategic decision on cyclosporine treatment of AA.

Could inflammation contribute to salivary gland dysfunction in patients with chronic heart failure?

Heart failure (HF) is one of the leading causes of death worldwide. HF results not only in cardiovascular dysfunction, but also numerous pathologies in the oral cavity and salivary glands. The present study is the first to evaluate whether salivary inflammatory and anti-inflammatory factors may be related with the occurrence of hyposalivation in HF patients. We also evaluated the potential of salivary biomarkers in the diagnostics of HF. The study included 30 women with HF and 30 sex- and age-matched healthy controls. We demonstrated significantly higher levels of pro-inflammatory cytokines, anti-inflammatory cytokines, Th1, Th2, Th17, chemokines and growth factors in unstimulated saliva of HF patients compared to controls. However, the results do not indicate dominance of either branch of the immune response. The concentration of selected biomarkers is significantly higher in patients with HF and salivary gland dysfunction compared to patients with normal saliva secretion and healthy subjects (IL-1β, TNF-α, IL-7, IL-13, INF-γ, IL-12, IL-15, IL-5, IL-6, IL-9, IL-17, MCP-1/CCL-2, EOTAXIN/CCL11, RANTES/CCL5, GM-CSF, VEGF, FGF basic, PDFG-BB). Multivariate regression analysis showed that the content of salivary cytokines, chemokines and growth factors is highly dependent on salivary gland function, i.e. salivary flow rate, total protein content and amylase activity. Using receiver operating characteristic (ROC) analysis, we showed that salivary TNF-α, INF-γ, IL-12 and EOTAXIN/CCL11 differentiated patients with HF and hyposalivation with the highest sensitivity and specificity compared to patients with normal salivary secretion and controls. Interestingly, the content of some pro- and anti-inflammatory mediators in saliva significantly exceeds their concentration in plasma. In addition, salivary biomarker levels do not reflect their plasma content, which may suggest a different nature/severity of inflammatory changes at the central (blood) and local (salivary) levels. Although our study was purely observational, the significantly higher concentration of inflammatory parameters in saliva compared to plasma, as well as the lack of saliva-blood correlation, may suggest increased production/secretion of these compounds in salivary cells of HF patients. ROC analysis did not confirm the diagnostic utility of salivary cytokines and chemokines in the differential diagnosis of HF patients.

Iristectorigenin A exerts novel protective properties against airway inflammation and mucus hypersecretion in OVA-induced asthmatic mice: Iristectorigenin A ameliorates asthma phenotype

BACKGROUND

Despite the substantial amount of efforts made to reduce morbidity and improve respiratory management, asthma control remained a major challenge for severe patients. Plant isoflavones, one of the most estrogenic compounds, are considered a potential alternative therapy for asthma. Iristectorigenin A, a naturally occurring isoflavone, is extracted from a variety of medical plants and its biological activity has not been reported previously.

PURPOSE

In present study, we aim to reveal the potential therapeutic role of Iristectorigenin A against acute asthmatic mice.

STUDY DESIGN

We established ovalbumin (OVA) induced asthmatic murine model and orally administrated Iristectorigenin A at concentration of 5 and 10 mg/kg and dexamethasone as a positive control substance.

METHODS

Asthmatic murine model was established with OVA sensitization and challenge. Lung function was assessed with FinePoint Ventilation system recording lung resistance (RI) and lung compliance (Cydn). White cells were sorted and counted in BALF. Histopathological assessment was conducted by H&E, PAS, and Masson's trichrome staining on paraffin embedded lung tissues. BALF content of IL-4, IL-5, IL-33, IL-13, INF-γ, IL-9 and serum IgE, IgG1 were measured using ELISA kit. Expression levels of mRNAs associated with inflammatory cytokines and goblet cell metaplasia were evaluated via quantitative RT-PCR. Protein expression levels of FOXA3, MUC5AC, SPDEF were estimated by immunohistochemistry on lung tissue, while NOTCH1 and NOTCH2 expressions were evaluated by western blotting analysis.

RESULTS

Iristectorigenin A resulted in improved airway hyperresponsiveness (AHR) mirrored by decreased RI and increased Cydn. With Iristectorigenin A, we also observed reduced number of BALF leukocytes, improved inflammatory cell infiltration in lung tissue, decreased content of BALF IL-4, IL-5, IL-33, but not IL-13, INF-γ, IL-9, and their mRNA levels, along with decreased levels of OVA-specific IgE, IgG1 in asthmatic mice. Additionally, Iristectorigenin A exhibited significant therapeutic potential on attenuating mucus production reflected by mitigated FOXA3 and MUC5AC immunostaining on the airway epithelium, as well as decreased mRNAs associated with goblet cell metaplasia. At last, a decrease in elevated expression level of NOTCH2, but not NOTCH1, in asthmatic mice lung tissue was observed by western blotting analysis.

CONCLUSION

Our study provides strong evidence that Iristectorigenin A can be potential therapeutic agent ameliorating airway inflammation and mucus hypersecretion in allergic asthma. This is a first research reported the potential of Iristectorigenin A as an alternative therapeutic agent.

Mouse pulmonary interstitial macrophages mediate the pro-tumorigenic effects of IL-9

Although IL-9 has potent anti-tumor activity in adoptive cell transfer therapy, some models suggest that it can promote tumor growth. Here, we show that IL-9 signaling is associated with poor outcomes in patients with various forms of lung cancer, and is required for lung tumor growth in multiple mouse models. CD4+ T cell-derived IL-9 promotes the expansion of both CD11c+ and CD11c- interstitial macrophage populations in lung tumor models. Mechanistically, the IL-9/macrophage axis requires arginase 1 (Arg1) to mediate tumor growth. Indeed, adoptive transfer of Arg1+ but not Arg1- lung macrophages to Il9r-/- mice promotes tumor growth. Moreover, targeting IL-9 signaling using macrophage-specific nanoparticles restricts lung tumor growth in mice. Lastly, elevated expression of IL-9R and Arg1 in tumor lesions is associated with poor prognosis in lung cancer patients. Thus, our study suggests the IL-9/macrophage/Arg1 axis is a potential therapeutic target for lung cancer therapy.

IL-9 Producing Tumor-Infiltrating Lymphocytes and Treg Subsets Drive Immune Escape of Tumor Cells in Non-Small Cell Lung Cancer

Although lung cancer is the leading cause of cancer deaths worldwide, the mechanisms how lung cancer cells evade the immune system remain incompletely understood. Here, we discovered IL-9-dependent signaling mechanisms that drive immune evasion in non-small cell lung cancer (NSCLC). We found increased IL-9 and IL-21 production by T cells in the tumoral region of the lung of patients with NSCLC, suggesting the presence of Th9 cells in the lung tumor microenvironment. Moreover, we noted IL-9 producing Tregs in NSCLC. IL-9 target cells in NSCLC consisted of IL-9R+ tumor cells and tumor-infiltrating lymphocytes. In two murine experimental models of NSCLC, and in vitro, IL-9 prevented cell death and controlled growth of lung adenocarcinoma cells. Targeted deletion of IL-9 resulted in successful lung tumor rejection in vivo associated with an induction of IL-21 and reduction of Treg cells. Finally, anti-IL-9 antibody immunotherapy resulted in suppression of tumor development even in established experimental NSCLC and was associated with reduced IL-10 production in the lung. In conclusion, our findings indicate that IL-9 drives immune escape of lung tumor cells via effects on tumor cell survival and tumor infiltrating T cells. Thus, strategies blocking IL-9 emerge as a new approach for clinical therapy of lung cancer.

Changes in esophagus interstitial cells of Cajal in response to acute stress

BACKGROUND

Thoracic trauma is common, and traffic accident-related traumatic injury can cause acute stress leading to esophageal motility disorders. Interstitial cells of Cajal (ICCs) are regarded as gastrointestinal pacemaker cells.

AIM

This study explored the mechanism underlying changes in lower esophagus ICCs under acute stress conditions.

METHODS

Fifty adult rabbits, randomly divided into one healthy control and four study groups, were subjected to right chest puncture using a Hopkinson bar. Thereafter, one group was immediately subjected to lower esophagectomy, whereas the other three groups were maintained for 24, 48 and 72 h after puncture and subjected to lower esophagectomy. Immunohistochemistry was used to detect ICC distribution, morphology and density, and TUNEL assays were used to determine ICC apoptosis. Enzyme-linked immunosorbent assays (ELISAs) were used to measure cortisol, epinephrine, dopamine, IL-9, cholecystokinin (CCK) and vasoactive intestinal peptide (VIP). Western blotting and RT-PCR were performed to detect changes in SCF/c-kit and nNOS pathways.

RESULTS

After puncture, lung tissue was hemorrhaged, alveoli in puncture areas were destroyed, esophageal pH was decreased, and serum cortisol, epinephrine and dopamine levels increased. ICC numbers increased and apoptotic ICCs decreased in all stress groups after puncture (all p < .01). IL-9, CCK and VIP levels in lower esophagus tissue were increased after puncture (all p < .01). Moreover, SCF/c-kit and nNOS pathways were upregulated in response to stress (all p < .01).

CONCLUSIONS

Acute stress promotes increases in lower esophageal ICCs that might affect esophagus ICC functions and esophageal motility.

Characterization of the Transient Deficiency of PKC Isozyme Levels in Immature Cord Blood T Cells and Its Connection to Anti-Allergic Cytokine Profiles of the Matured Cells

Cord blood T cells (CBTC) from a proportion of newborns express low/deficient levels of some protein kinase C (PKC) isozymes, with low levels of PKCζ correlating with increased risk of developing allergy and associated decrease in interferon-gamma (IFN-γ) producing T cells. Interestingly, these lower levels of PKCζ were increased/normalized by supplementing women during pregnancy with n-3 polyunsaturated fatty acids. However, at present, we have little understanding of the transient nature of the deficiency in the neonate and how PKCζ relates to other PKC isozymes and whether their levels influence maturation into IFN-γ producing T cells. There is also no information on PKCζ isozyme levels in the T cell subpopulations, CD4⁺ and CD8⁺ cells. These issues were addressed in the present study using a classical culture model of neonatal T cell maturation, initiated with phytohaemagglutinin (PHA) and recombinant human interleukin-2 (rhIL-2). Of the isozymes evaluated, PKCζ, β2, δ, μ, ε, θ and λ/ι were low in CBTCs. The PKC isozyme deficiencies were also found in the CD4⁺ and CD8⁺ T cell subset levels of the PKC isozymes correlated between the two subpopulations. Examination of changes in the PKC isozymes in these deficient cells following addition of maturation signals showed a significant increase in expression within the first few hours for PKCζ, β2 and μ, and 1–2 days for PKCδ, ε, θ and λ/ι. Only CBTC PKCζ isozyme levels correlated with cytokine production, with a positive correlation with IFN-γ, interleukin (IL)-2 and tumour necrosis factor-alpha (TNF), and a negative association with IL-9 and IL-10. The findings reinforce the specificity in using CBTC PKCζ levels as a biomarker for risk of allergy development and identify a period in which this can be potentially ‘corrected’ after birth.

Interleukin-35 Promotes Th9 Cell Differentiation in IgG4-Related Disorders: Experimental Data and Review of the Literature

IgG4-related disease (IgG4-RD) is characterized by intense infiltration of IgG4-positive plasma cells in affected organs. However, the mechanisms acting in the immune responses in IgG4-RD are not fully understood. The aim of this study was to dissect the mechanism underlying the immunoglobulin class switch in IgG4-RD by addressing the crosstalk between IL-35-producing and Th9 cells. The expression level of IL-35 was examined in plasma samples from patients with hepatobiliary and/or pancreatic manifestations of IgG4-RD. Our data demonstrate that IgG4-RD patients exhibit significantly high-level productions of IL-35 as compared to disease and healthy controls. We detected the two subunits of IL-35, EBI3 and IL-12p35, in the two major affected organs, liver and pancreatic tissue, from IgG4-RD. The EBI3- and IL-12p35-positive cells were significantly higher in affected organs in IgG4-RD as compared to disease controls. The colocalization of EBI3 with CD19 and CD38, markers for B cells, suggest the presence of IL-35-producing B cells in affected organs in IgG4-RD. The effects of IL-35 in Th9 differentiation and IL-9 in production of immunoglobulin were then assessed. Surprisingly, IL-35 treatment promoted naïve CD4 T cell differentiating towards Th9 cells through IRF4 signaling. As a consequence, IL-9 secreted by Th9 cells promoted the differentiation of plasma cells and production of IgG1 and IgG4, predominantly IgG4. In conclusion, our data demonstrate that IL-35 actively participates in the process of inflammation and plays an important role in Th9 differentiation resulting in an immunoglobulin class switch towards IgG4.

Association of IL-9, IL-10, and IL-17 Cytokines With Hepatic Fibrosis in Human Schistosoma mansoni Infection

This is a case series study to evaluate immunological markers associated with schistosomiasis advanced fibrosis, including 69 patients from an endemic area from the State of Sergipe and from the Hepatology Service of the University Hospital in Sergipe, Brazil. Hepatic fibrosis was classified based on Niamey protocol for ultrasonography (US). Immune response to Schistosoma mansoni antigens was evaluated by stimulating peripheral blood mononuclear cells (PBMCs) from these patients with either adult worm (SWAP-10 μg/ml) or egg (SEA-10 μg/ml) antigens or purified protein derivative of turberculin (PPD-10 μg/ml) or phytohemagglutinin (PHA-1 μg/ml) for 72 h. The levels of IFN-γ, TNF-α, IL-5, IL-10, and IL-17 were measured in these supernatants by ELISA and IL-9 by Luminex. Single nucleotide polymorphisms in IL-17, IL10, and CD209 genes were genotyped using TaqMan probe by qPCR. Higher levels of IL-9, IL-10, and IL-17 were found in PBMC supernatants of patients with advanced hepatic fibrosis. Direct correlations were detected between IL-9 and IL-17 levels with US spleen sizes, portal vein diameters, and periportal thickening. The CD209 rs2287886 AG polymorphism patients produce higher IL-17 levels. Together, these data suggest a role of these cytokines in the immunopathogenesis of advanced fibrosis in human schistosomiasis.

Association of IL-9, IL-10, and IL-17 Cytokines With Hepatic Fibrosis in Human Schistosoma mansoni Infection

This is a case series study to evaluate immunological markers associated with schistosomiasis advanced fibrosis, including 69 patients from an endemic area from the State of Sergipe and from the Hepatology Service of the University Hospital in Sergipe, Brazil. Hepatic fibrosis was classified based on Niamey protocol for ultrasonography (US). Immune response to Schistosoma mansoni antigens was evaluated by stimulating peripheral blood mononuclear cells (PBMCs) from these patients with either adult worm (SWAP-10 μg/ml) or egg (SEA-10 μg/ml) antigens or purified protein derivative of turberculin (PPD-10 μg/ml) or phytohemagglutinin (PHA-1 μg/ml) for 72 h. The levels of IFN-γ, TNF-α, IL-5, IL-10, and IL-17 were measured in these supernatants by ELISA and IL-9 by Luminex. Single nucleotide polymorphisms in IL-17, IL10, and CD209 genes were genotyped using TaqMan probe by qPCR. Higher levels of IL-9, IL-10, and IL-17 were found in PBMC supernatants of patients with advanced hepatic fibrosis. Direct correlations were detected between IL-9 and IL-17 levels with US spleen sizes, portal vein diameters, and periportal thickening. The CD209 rs2287886 AG polymorphism patients produce higher IL-17 levels. Together, these data suggest a role of these cytokines in the immunopathogenesis of advanced fibrosis in human schistosomiasis.

Calcitriol attenuates TLR2/IL-33 signaling pathway to repress Th9 cell differentiation and potentially limits the pathophysiology of rheumatoid arthritis

There is limited information regarding the TLR2 signaling pathway involved in Th9 cell differentiation. The role of calcitriol in regulating TLR2-mediated Th9 cell development is unknown. Thus, we aimed to unravel the TLR2 signaling pathway in Th9 cells and its regulation by calcitriol. We have used n = 5-6 animals for each murine experiment. Human studies involved five healthy volunteers. Moreover, ten healthy individuals and ten RA patients were included in the study. Murine and human Th9 cells were treated with Calcitriol (100 nM) and Pam₃CSK₄ (2 µg/mL). The number of IL-9+ve cells was determined by flow cytometry. Real-time PCR was used to assess the gene expression. Serum 25(OH)D₃ levels were determined by HPLC. We observed that TLR2 signals via IL-33/ST2 in Th9 cells. Increased TLR2 expression associated with increased IL9 expression and augmented disease severity in RA patients. Calcitriol attenuated TLR2 signaling in murine and human Th9 cells. Low serum vitamin D3 level negatively associated with increased IL-9 and TLR2 expression and disease severity in RA patients. Our data suggest a potential role of calcitriol to ameliorate the disease severity of RA patients.

Proteome analysis revealed the essential functions of protein phosphatase PP2A in the induction of Th9 cells

Proteomic analysis identifies post-translational functions of proteins, which remains obscure in transcriptomics. Given the important functions of Th9 cells in anti-tumor immunity, we performed proteome analysis of Th9 cells to understand the involvement of proteins that might be crucial for the anti-tumor functions of Th9 cells. Here we performed a comprehensive proteomic analysis of murine Th0 and Th9 cells, and identified proteins that are enriched in Th9 cells. Pathway analysis identified an abundance of phosphoproteins in the proteome of Th9 cells as compared to Th0 cells. Among upregulated phosphoproteins, Ppp2ca (catalytic subunit of protein phosphatase, PP2A) was found to be highly enriched in Th9 cells. Although the role of PP2A has been shown to regulate the differentiation and functions of Th1, Th2, Th17 and Tregs, its role in the differentiation and functions of Th9 cells is not identified yet. Here we found that PP2A is required for the induction of Th9 cells, as PP2A inhibition leads to the suppression of IL-9 and expression of key transcription factors of Th9 cells. PP2A inhibition abrogates Th9 cell-mediated anti-tumor immune response in B16-OVA melanoma tumor model. Thus, we report that PP2A is essential for the differentiation and anti-tumor functions of Th9 cells.

Interleukin-9 Inhibits Lung Metastasis of Melanoma through Stimulating Anti-Tumor M1 Macrophages

Interleukin-9 (IL-9) is well known for its role in allergic inflammation. For cancer, both pro- and anti-tumor effects of IL-9 were controversially reported, but the impact of IL-9 on tumor metastasis has not yet been clarified. In this study, IL-9 was expressed as a secretory form (sIL-9) and a membrane-bound form (mbIL-9) on B16F10 melanoma cells. The mbIL-9 was engineered as a chimeric protein with the transmembrane and cytoplasmic region of TNF-α. The effect of either mbIL-9 or sIL-9 expressing cells were analyzed on the metastasis capability of the cancer cells. After three weeks of tumor implantation into C57BL/6 mice through the tail vein, the number of tumor modules in lungs injected with IL-9 expressing B16F10 was 5-fold less than that of control groups. The percentages of CD4+ T cells, CD8+ T cells, NK cells, and M1 macrophages considerably increased in the lungs of the mice injected with IL-9 expressing cells. Among them, the M1 macrophage subset was the most significantly enhanced. Furthermore, peritoneal macrophages, which were stimulated with either sIL-9 or mbIL-9 expressing transfectant, exerted higher anti-tumor cytotoxicity compared with that of the mock control. The IL-9-stimulated peritoneal macrophages were highly polarized to M1 phenotype. Stimulation of RAW264.7 macrophages with sIL-9 or mbIL-9 expressing cells also significantly increased the cytotoxicity of those macrophages against wild-type B16F10 cells. These results clearly demonstrate that IL-9 can induce an anti-metastasis effect by enhancing the polarization and proliferation of M1 macrophages.

HMGB1-induced ILC2s activate dendritic cells by producing IL-9 in asthmatic mouse model

Asthma is a disease of the respiratory system that is commonly considered a T-helper 2 (Th2) cell-associated inflammatory disease. Group 2 innate lymphoid cells (ILC2s) promote the inflammatory responses in asthma by secreting type 2 cytokines. Interleukin (IL)-9 also serves as a promoting factor in asthma and it is well known that ILC2s have an autocrine effect of IL-9 to sustain their survival and proliferation. However, the specific role of ILC2-derived IL-9 in asthma remains unclear. HMGB1 (High-Mobility Group Box-1) is a nuclear protein, and Previous studies have shown that HMGB1 can regulate the differentiation of T-helper cells and participate in the development of asthma. But whether HMGB1 can regulate the innate lymphocytes in the pathological process of asthma is unknown. In this study we have shown increased presence of HMGB1 protein in the lung of mice with asthma, which was associated with increased secretion of IL-9 by ILC2s. This led to the activation of dendritic cells (DCs) that can accelerate the differentiation of Th2 cells and worsen the severity of asthma. Taken together, our study provides a complementary understanding of the asthma development and highlights a novel inflammatory pathway in the pathogenesis of asthma.

Dysregulated Gut Homeostasis Observed Prior to the Accumulation of the Brain Amyloid-β in Tg2576 Mice

Amyloid plaques in Alzheimer's disease (AD) are associated with inflammation. Recent studies demonstrated the involvement of the gut in cerebral amyloid-beta (Aβ) pathogenesis; however, the mechanisms are still not well understood. We hypothesize that the gut bears the Aβ burden prior to brain, highlighting gut-brain axis (GBA) interaction in neurodegenerative disorders. We used pre-symptomatic (6-months) and symptomatic (15-months) Tg2576 mouse model of AD compared to their age-matched littermate WT control. We identified that dysfunction of intestinal epithelial barrier (IEB), dysregulation of absorption, and vascular Aβ deposition in the IEB occur before cerebral Aβ aggregation is detectible. These changes in the GBA were associated with elevated inflammatory plasma cytokines including IL-9, VEGF and IP-10. In association with reduced cerebral myelin tight junction proteins, we identified reduced levels of systemic vitamin B12 and decrease cubilin, an intestinal B12 transporter, after the development of cerebral Aβ pathology. Lastly, we report Aβ deposition in the intestinal autopsy from AD patients with confirmed cerebral Aβ pathology that is not present in intestine from non-AD controls. Our data provide evidence that gut dysfunction occurs in AD and may contribute to its etiology. Future therapeutic strategies to reverse AD pathology may involve the early manipulation of gut physiology and its microbiota.

Extranodal NK/T-Cell Lymphomas: The Role of Natural Killer Cells and EBV in Lymphomagenesis

Keywords: NK cells, extranodal NK/T-cell lymphoma, EBV.

IL-9 and Mast Cells Are Key Players of Candida albicans Commensalism and Pathogenesis in the Gut

Candida albicans is implicated in intestinal diseases. Identifying host signatures that discriminate between the pathogenic versus commensal nature of this human commensal is clinically relevant. In the present study, we identify IL-9 and mast cells (MCs) as key players of Candida commensalism and pathogenicity. By inducing TGF-β in stromal MCs, IL-9 pivotally contributes to mucosal immune tolerance via the indoleamine 2,3-dioxygenase enzyme. However, Candida-driven IL-9 and mucosal MCs also contribute to barrier function loss, dissemination, and inflammation in experimental leaky gut models and are upregulated in patients with celiac disease. Inflammatory dysbiosis occurs with IL-9 and MC deficiency, indicating that the activity of IL-9 and MCs may go beyond host immunity to include regulation of the microbiota. Thus, the output of the IL-9/MC axis is highly contextual during Candida colonization and reveals how host immunity and the microbiota finely tune Candida behavior in the gut.

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IL-9/IL-9R signaling affects MC function in mucosal candidiasis

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IL-9 and mucosal MCs contribute to barrier function loss in leaky gut models

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IL-9 and stromal MCs induce local protective tolerance in infection via IDO1

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IL-9 and mucosal MCs expand and IDO1 decreases in human celiac disease

Transcription factor networks in aged naïve CD4 T cells bias lineage differentiation

With reduced thymic activity, the population of naïve T cells in humans is maintained by homeostatic proliferation throughout adult life. In young adults, naïve CD4 T cells have enormous proliferative potential and plasticity to differentiate into different lineages. Here, we explored whether naïve CD4 T-cell aging is associated with a partial loss of this unbiased multipotency. We find that naïve CD4 T cells from older individuals have developed a propensity to develop into TH9 cells. Two major mechanisms contribute to this predisposition. First, responsiveness to transforming growth factor β (TGFβ) stimulation is enhanced with age due to an upregulation of the TGFβR3 receptor that results in increased expression of the transcription factor PU.1. Secondly, aged naïve CD4 T cells display altered transcription factor profiles in response to T-cell receptor stimulation, including enhanced expression of BATF and IRF4 and reduced expression of ID3 and BCL6. These transcription factors are involved in TH9 differentiation as well as IL9 transcription suggesting that the aging-associated changes in the transcription factor profile favor TH9 commitment.

An Update on Interleukin-9: From Its Cellular Source and Signal Transduction to Its Role in Immunopathogenesis

Interleukin-9 (IL-9) is a pleiotropic cytokine and was primarily studied in the context of T helper 2 (TH2)-associated immuno-pathological conditions such as asthma and parasitic infections. There was a paradigm shift in the biology of IL-9 after the recent discovery of TH9 cells, a new subtype of TH cells which secrete IL-9 in copious amounts. This has resulted in renewed interest in this cytokine, which was neglected since discovery because it was considered it to be just another TH2 cytokine. Recent studies have shown that it has multiple cellular sources and is critically involved in the immune-pathogenesis of inflammatory diseases and in guarding immune tolerance. In this review, we will discuss its discovery, gene organization, cellular sources, and signaling pathways. Especially, we will give an update on the recent development regarding its relevance in the immune pathogenesis of human diseases.

Th9 Cells as a New Player in Inflammatory Skin Disorders

CD4+T cells are composed of different subpopulations that differ in developmental pathways, surface markers, and their products. Among the catalog of these cells is Th9 cell subset that has a great capacity of Interleukin (IL)-9 production. They could be involved in the pathogenic or protective immune responses. Therefore, it is important to know how Th9 cells and cytokines influence the function of the human immune system as multitasking machinery, both in isolation or after the interaction with other surrounding cells. Since an important characteristic of Th9 cells is their tropism for skin, this article reviews the physiological and pathophysiological functions of Th9 and its cytokines under normal conditions and inflammatory skin disorders.

Interleukin 9 Alters Epithelial Barrier and E-cadherin in Eosinophilic Esophagitis

BACKGROUND

Eosinophilic esophagitis (EoE) is a chronic TH2-assocated inflammatory condition accompanied by substantial impairments in epithelial barrier function and increased numbers of interleukin 9 (IL-9) expressing inflammatory cells. While IL-9 is known to affect barrier function in the intestine, the functional effects of IL-9 on the esophagus are unclear. Herein we aimed to understand the expression of the IL-9 receptor and effects of IL-9 on the epithelium in EoE.

METHODS

We used esophageal biopsies from pediatric EoE patients with active and inactive disease to analyze the expression of the IL-9 receptor, the adherens junction protein E-cadherin and the tight junction protein claudin-1. We treated primary human esophageal epithelial cells with IL-9 to understand its effects on E-cadherin expression and function.

RESULTS

Active EoE subjects had increased epithelial expression of IL-9 receptor mRNA and protein (P < 0.05) and decreased membrane bound E-cadherin (P < 0.01) and claudin-1 (P < 0.05) expression. IL-9 receptor expression and mislocalized claudin-1 positively correlated and while membrane bound E-cadherin expression negatively correlated with the degree of histologic epithelial remodeling (P < 0.05). IL-9 decreased epithelial resistance in stratified primary human esophageal epithelial cells (P < 0.01) and membrane bound E-cadherin in epithelial cell monolayers (P < 0.01).

CONCLUSIONS

These data suggest that IL-9, its receptor, and its effects on E-cadherin may be important mechanisms for epithelial barrier disruption in EoE.

Zinc supplementation plays a crucial role in T helper 9 differentiation in allogeneic immune reactions and non-activated T cells

T helper (Th) 9 cells play a critical role in immune-mediated diseases, including allergic airway inflammation, autoimmune diseases, and cancer development. Thus, the promotion or suppression of Th9 cell differentiation, transcriptional control, and function is very important for a healthy immune system. Interestingly, T cell maturation, differentiation and function are highly dependent on the individuals' zinc status. This is especially seen in zinc deficient individuals as in the elderly population often suffering of autoimmunity and increased incidence of infections. In this regard, this study examines the impact of zinc supplementation in pharmacological doses on Th9 differentiation in two in vitro models: 1) in mixed lymphocyte cultures (MLC) displaying allogeneic activated T cells in graft versus host disease, and 2) on non-activated resting T cells in peripheral blood mononuclear cells (PBMC). On the one hand, zinc supplementation significantly diminishes IL-4-induced Th9 differentiation in MLC thereby ameliorating this pro-inflammatory allogeneic immunoreaction. On the other hand, Th9 cells are induced in resting T cells in PBMC hence triggering the immunological defense. Thus, zinc supplementation can be considered as useful additive to dampen unwanted allogeneic immunoreactions. Moreover, the pro-inflammatory immune defense in non-reactive T cells can be strengthened, which is a frequent issue in the elderly population having a weakened immune response against invading pathogens.