Th9 cells in inflammatory bowel diseases

Inborn errors of immunity reveal molecular requirements for generation and maintenance of human CD4+ IL-9-expressing cells

BACKGROUND

CD4+ T cells play essential roles in adaptive immunity. Distinct CD4+ T-cell subsets-TH1, TH2, TH17, TH22, T follicular helper, and regulatory T cells-have been identified, and their contributions to host defense and immune regulation are increasingly well defined. IL-9-producing TH9 cells were first described in 2008 and appear to play both protective and pathogenic roles in human immunity. However, key requirements for generating human TH9 cells remain incompletely defined.

OBJECTIVE

We sought to define signaling pathways that regulate IL-9 production by human CD4+ T cells.

METHODS

Human naive and memory CD4+ T cells were cultured under different conditions, and the molecular mechanisms regulating IL-9 induction were determined by assessing the ability of CD4+ T cells from a broad range of patients (n = 92) with pathogenic variants in key immune genes (n = 21) to differentiate into IL-9+ cells.

RESULTS

We identified 2 culture conditions that yielded IL-9-expressing cells from naive CD4+ T cells and amplified IL-9 production by in vivo-generated memory CD4+ T cells: TGF-β plus IL-4 (ie, TH9 polarizing condition), and the combination of IL-21, IL-23, IL-6, IL-1β, and TGF-β (ie, TH17 polarizing condition). Combining these conditions had a synergistic effect in generating IL-9+CD4+ T cells. IL-9 induction required STAT3-activating cytokines as well as intact signaling via the T-cell receptor and STAT5. Importantly, IL-9 induction was restrained by IFN-γ/STAT1 and IL-10.

CONCLUSIONS

Our findings revealed critical molecules involved in inducing/restraining IL-9 production by human CD4+ T cells, thereby identifying pathways that could be targeted to modulate IL-9 in health and disease.

The immune and microbial homeostasis determines the Candida-mast cells cross-talk in celiac disease

Celiac disease (CD) is an autoimmune enteropathy resulting from an interaction between diet, genome, and immunity. Although many patients respond to a gluten-free diet, in a substantive number of individuals, the intestinal injury persists. Thus, other factors might amplify the ongoing inflammation. Candida albicans is a commensal fungus that is well adapted to the intestinal life. However, specific conditions increase Candida pathogenicity. The hypothesis that Candida may be a trigger in CD has been proposed after the observation of similarity between a fungal wall component and two CD-related gliadin T-cell epitopes. However, despite being implicated in intestinal disorders, Candida may also protect against immune pathologies highlighting a more intriguing role in the gut. Herein, we postulated that a state of chronic inflammation associated with microbial dysbiosis and leaky gut are favorable conditions that promote C. albicans pathogenicity eventually contributing to CD pathology via a mast cells (MC)-IL-9 axis. However, the restoration of immune and microbial homeostasis promotes a beneficial C. albicans-MC cross-talk favoring the attenuation of CD pathology to alleviate CD pathology and symptoms.

Helicobacter pylori in Inflammatory Bowel Diseases: Active Protagonist or Innocent Bystander?

Helicobacter pylori (H. pylori) infection is a prominent entity within human infectious diseases which cause chronic gastritis, peptic ulcers, gastric malignancies, and extragastric disorders. Its persistent colonization can lead to a systemic inflammatory cascade, potentially instigating autoimmune responses and contributing to the pathogenesis of autoimmune diseases. While the specific etiopathogenesis of inflammatory bowel diseases (IBDs) is still unknown, it is widely recognized that immunological, genetic, and environmental factors are implicated. Various bacterial and viral pathogens have been implicated in the pathogenesis of IBDs. Numerous studies suggest a correlation between H. pylori infection and IBDs. While subject to debate, this link suggests that the bacterium's presence somehow impacts the progression of IBDs by modifying the diversity of the gut microbiota, consequently altering local chemical profiles and disrupting the pattern of gut immune response. However, epidemiological evidence indicates a protective role of H. pylori infection against the onset of autoimmune diseases. Additionally, laboratory findings demonstrate H. pylori's capacity to promote immune tolerance and restrict inflammatory reactions. The aim of this review is to elucidate the proposed mechanisms and confounding factors that underlie the potential association between H. pylori infection and IBDs.

Distinct gene expression signatures comparing latent tuberculosis infection with different routes of Bacillus Calmette-Guérin vaccination

Tuberculosis remains an international health threat partly because of limited protection from pulmonary tuberculosis provided by standard intradermal vaccination with Bacillus of Calmette and Guérin (BCG); this may reflect the inability of intradermal vaccination to optimally induce pulmonary immunity. In contrast, respiratory Mycobacterium tuberculosis infection usually results in the immune-mediated bacillary containment of latent tuberculosis infection (LTBI). Here we present RNA-Seq-based assessments of systemic and pulmonary immune cells from LTBI participants and recipients of intradermal and oral BCG. LTBI individuals uniquely display ongoing immune activation and robust CD4 T cell recall responses in blood and lung. Intradermal BCG is associated with robust systemic immunity but only limited pulmonary immunity. Conversely, oral BCG induces limited systemic immunity but distinct pulmonary responses including enhanced inflammasome activation potentially associated with mucosal-associated invariant T cells. Further, IL-9 is identified as a component of systemic immunity in LTBI and intradermal BCG, and pulmonary immunity following oral BCG.

A Narrative Review of Cytokine Networks: Pathophysiological and Therapeutic Implications for Inflammatory Bowel Disease Pathogenesis

Inflammatory bowel disease (IBD) is a lifelong inflammatory immune mediated disorder, encompassing Crohn's disease (CD) and ulcerative colitis (UC); however, the cause and specific pathogenesis of IBD is yet incompletely understood. Multiple cytokines produced by different immune cell types results in complex functional networks that constitute a highly regulated messaging network of signaling pathways. Applying biological mechanisms underlying IBD at the single omic level, technologies and genetic engineering enable the quantification of the pattern of released cytokines and new insights into the cytokine landscape of IBD. We focus on the existing literature dealing with the biology of pro- or anti-inflammatory cytokines and interactions that facilitate cell-based modulation of the immune system for IBD inflammation. We summarize the main roles of substantial cytokines in IBD related to homeostatic tissue functions and the remodeling of cytokine networks in IBD, which may be specifically valuable for successful cytokine-targeted therapies via marketed products. Cytokines and their receptors are validated targets for multiple therapeutic areas, we review the current strategies for therapeutic intervention and developing cytokine-targeted therapies. New biologics have shown efficacy in the last few decades for the management of IBD; unfortunately, many patients are nonresponsive or develop therapy resistance over time, creating a need for novel therapeutics. Thus, the treatment options for IBD beyond the immune-modifying anti-TNF agents or combination therapies are expanding rapidly. Further studies are needed to fully understand the immune response, networks of cytokines, and the direct pathogenetic relevance regarding individually tailored, safe and efficient targeted-biotherapeutics.

Neuroimmune interplay in kidney health and disease: Role of renal nerves

Renal nerves and their role in physiology and disease have been a topic of increasing interest in the past few decades. Renal inflammation contributes to many cardiorenal disease conditions, including hypertension, chronic kidney disease, and polycystic kidney disease. Much is known about the role of renal sympathetic nerves in physiology - they contribute to the regulation of sodium reabsorption, renin release, and renal vascular resistance. In contrast, far less is known about afferent, or "sensory," renal nerves, which convey signals from the kidney to the brain. While much remains unknown about these nerves in the context of normal physiology, even less is known about their contribution to disease states. Furthermore, it has become apparent that the crosstalk between renal nerves and the immune system may augment or modulate disease. Research from other fields, especially pain research, has provided critical insight into neuroimmune crosstalk. Sympathetic renal nerve activity may increase immune cell recruitment, but far less work has been done investigating the interplay between afferent renal nerves and the immune system. Evidence from other fields suggests that inflammation may augment afferent renal nerve activity. Furthermore, these nerves may exacerbate renal inflammation through the release of afferent-specific neurotransmitters.

Immune response modulation in inflammatory bowel diseases by Helicobacter pylori infection

Many studies point to an association between Helicobacter pylori (H. pylori) infection and inflammatory bowel diseases (IBD). Although controversial, this association indicates that the presence of the bacterium somehow affects the course of IBD. It appears that H. pylori infection influences IBD through changes in the diversity of the gut microbiota, and hence in local chemical characteristics, and alteration in the pattern of gut immune response. The gut immune response appears to be modulated by H. pylori infection towards a less aggressive inflammatory response and the establishment of a targeted response to tissue repair. Therefore, a T helper 2 (Th2)/macrophage M2 response is stimulated, while the Th1/macrophage M1 response is suppressed. The immunomodulation appears to be associated with intrinsic factors of the bacteria, such as virulence factors - such oncogenic protein cytotoxin-associated antigen A, proteins such H. pylori neutrophil-activating protein, but also with microenvironmental changes that favor permanence of H. pylori in the stomach. These changes include the increase of gastric mucosal pH by urease activity, and suppression of the stomach immune response promoted by evasion mechanisms of the bacterium. Furthermore, there is a causal relationship between H. pylori infection and components of the innate immunity such as the NLR family pyrin domain containing 3 inflammasome that directs IBD toward a better prognosis.

Effect of aqueous extract of Trigonellafoenum-graecum L. seeds on Acetic acid- induced Ulcerative colitis in rats

Background: Ulcerative colitis (UC) is an inflammatory bowel disorder affecting the colonic mucosa, characterized by intense inflammation and mucosal damage. The present study aimed to evaluate the protective effect of the Trigonellafoenum-graecum L. (TFG) seeds in acetic acid-induced UC in rats. Materials and Methods: Male rats (n=30) were distributed into 5 groups as normal control, UC, standard, and two test groups. Colitis was induced by acetic acid in all the groups except the normal control group. Normal control and UC group received distilled water, the standard group was administered sulfasalazine at 100mg/kg body weight (bw), and test groups, TFG-I, and TFG-II received TFG seed extract at 500 and 1000 mg/kg bw, respectively. The duration of treatment was 7 days, and colitis was induced on day 8. Animals were sacrificed on day 9 and colonic tissue was dissected and collected for biochemical, molecular, and histological analysis. Results: The disease activity index score in standard, TFG-I, and TFG-II (3.33±0.21, 2.66±0.21, and 3.50±0.22) was significantly lesser (P<0.05) than scores in the UC group (4±0.01). The macroscopic score indicating the intensity of mucosal inflammation was significantly decreased (P≤ 0.01) to4.0±0.25, 3.16±0.30, and 3.83±0.40 in standard, TFG-I, and TFG-II groups, respectively compared to the UC group (4.66±0.21). Similarly, there was a significant reduction (P≤0.05) in histological scores of the standard, TFG-I, TFG-II (3.5±0.34, 1.25±0.34, 3.25±0.34) groups compared to the UC group (4.75±0.34). Biochemical assessment in the standard and test groups showed significant increase (P<0.05) in total protein, reduced glutathione (GSH), catalase (CAT), superoxide dismutase (SOD) levels whereas significant reduction (P<0.01) in malondialdehyde (MDA) levels compared to UC group. The pro-inflammatory cytokine TNF-α levels were significantly decreased (P<0.01) in standard, TFG-I, and TFG-II (-1.75±0.007, -0.27±0.17 and -0.51±0.002) when compared to the UC group (0.20±0.02). Conclusion: The study demonstrates the ability of TFG seeds in reducing the inflammatory and oxidative stress induced mucosal damage in acetic acid-induced UC in rats.

The Differentially Expressed Genes Responsible for the Development of T Helper 9 Cells From T Helper 2 Cells in Various Disease States: Immuno-Interactomics Study

BACKGROUND

T helper (Th) 9 cells are a novel subset of Th cells that develop independently from Th2 cells and are characterized by the secretion of interleukin (IL)-9. Studies have suggested the involvement of Th9 cells in variable diseases such as allergic and pulmonary diseases (eg, asthma, chronic obstructive airway disease, chronic rhinosinusitis, nasal polyps, and pulmonary hypoplasia), metabolic diseases (eg, acute leukemia, myelocytic leukemia, breast cancer, lung cancer, melanoma, pancreatic cancer), neuropsychiatric disorders (eg, Alzheimer disease), autoimmune diseases (eg, Graves disease, Crohn disease, colitis, psoriasis, systemic lupus erythematosus, systemic scleroderma, rheumatoid arthritis, multiple sclerosis, inflammatory bowel disease, atopic dermatitis, eczema), and infectious diseases (eg, tuberculosis, hepatitis). However, there is a dearth of information on its involvement in other metabolic, neuropsychiatric, and infectious diseases.

OBJECTIVE

This study aims to identify significant differentially altered genes in the conversion of Th2 to Th9 cells, and their regulating microRNAs (miRs) from publicly available Gene Expression Omnibus data sets of the mouse model using in silico analysis to unravel various pathogenic pathways involved in disease processes.

METHODS

Using differentially expressed genes (DEGs) identified from 2 publicly available data sets (GSE99166 and GSE123501) we performed functional enrichment and network analyses to identify pathways, protein-protein interactions, miR-messenger RNA associations, and disease-gene associations related to significant differentially altered genes implicated in the conversion of Th2 to Th9 cells.

RESULTS

We extracted 260 common downregulated, 236 common upregulated, and 634 common DEGs from the expression profiles of data sets GSE99166 and GSE123501. Codifferentially expressed ILs, cytokines, receptors, and transcription factors (TFs) were enriched in 7 crucial Kyoto Encyclopedia of Genes and Genomes pathways and Gene Ontology. We constructed the protein-protein interaction network and predicted the top regulatory miRs involved in the Th2 to Th9 differentiation pathways. We also identified various metabolic, allergic and pulmonary, neuropsychiatric, autoimmune, and infectious diseases as well as carcinomas where the differentiation of Th2 to Th9 may play a crucial role.

CONCLUSIONS

This study identified hitherto unexplored possible associations between Th9 and disease states. Some important ILs, including CCL1 (chemokine [C-C motif] ligand 1), CCL20 (chemokine [C-C motif] ligand 20), IL-13, IL-4, IL-12A, and IL-9; receptors, including IL-12RB1, IL-4RA (interleukin 9 receptor alpha), CD53 (cluster of differentiation 53), CD6 (cluster of differentiation 6), CD5 (cluster of differentiation 5), CD83 (cluster of differentiation 83), CD197 (cluster of differentiation 197), IL-1RL1 (interleukin 1 receptor-like 1), CD101 (cluster of differentiation 101), CD96 (cluster of differentiation 96), CD72 (cluster of differentiation 72), CD7 (cluster of differentiation 7), CD152 (cytotoxic T lymphocyte-associated protein 4), CD38 (cluster of differentiation 38), CX3CR1 (chemokine [C-X3-C motif] receptor 1), CTLA2A (cytotoxic T lymphocyte-associated protein 2 alpha), CTLA28, and CD196 (cluster of differentiation 196); and TFs, including FOXP3 (forkhead box P3), IRF8 (interferon regulatory factor 8), FOXP2 (forkhead box P2), RORA (RAR-related orphan receptor alpha), AHR (aryl-hydrocarbon receptor), MAF (avian musculoaponeurotic fibrosarcoma oncogene homolog), SMAD6 (SMAD family member 6), JUN (Jun proto-oncogene), JAK2 (Janus kinase 2), EP300 (E1A binding protein p300), ATF6 (activating transcription factor 6), BTAF1 (B-TFIID TATA-box binding protein associated factor 1), BAFT (basic leucine zipper transcription factor), NOTCH1 (neurogenic locus notch homolog protein 1), GATA3 (GATA binding protein 3), SATB1 (special AT-rich sequence binding protein 1), BMP7 (bone morphogenetic protein 7), and PPARG (peroxisome proliferator-activated receptor gamma, were able to identify significant differentially altered genes in the conversion of Th2 to Th9 cells. We identified some common miRs that could target the DEGs. The scarcity of studies on the role of Th9 in metabolic diseases highlights the lacunae in this field. Our study provides the rationale for exploring the role of Th9 in various metabolic disorders such as diabetes mellitus, diabetic nephropathy, hypertensive disease, ischemic stroke, steatohepatitis, liver fibrosis, obesity, adenocarcinoma, glioblastoma and glioma, malignant neoplasm of stomach, melanoma, neuroblastoma, osteosarcoma, pancreatic carcinoma, prostate carcinoma, and stomach carcinoma.

PU.1-driven Th9 Cells Promote Colorectal Cancer in Experimental Colitis Models Through Il-6 Effects in Intestinal Epithelial Cells

BACKGROUND AND AIMS

Colorectal cancer [CRC] is one of the most frequent malignancies, but the molecular mechanisms driving cancer growth are incompletely understood. We characterised the roles of the cytokine IL-9 and Th9 cells in regulating CRC development.

METHODS

CRC patient samples and samples from AOM/DSS treated mice were analysed for expression of IL-9, CD3, and PU.1 by FACS analysis and immunohistochemistry. IL-9 citrine reporter mice, IL-9 knockout mice, and PU.1 and GATA3 CD4-Cre conditional knockout mice were studied in the AOM/DSS model. DNA minicircles or hyper-IL-6 were used for overexpression of cytokines in vivo. Effects of IL-6 and IL-9 were determined in organoid and T cell cultures. Claudin2/3 expression was studied by western blotting and bacterial translocation by FISH.

RESULTS

We uncovered a significant expansion of IL-9- and PU.1-expressing mucosal Th9 cells in CRC patients, with particularly high levels in patients with colitis-associated neoplasias. PU.1+ Th9 cells accumulated in experimental colorectal neoplasias. Deficiency of IL-9 or inactivation of PU.1 in T cells led to impaired tumour growth in vivo, suggesting a protumoral role of Th9 cells. In contrast, GATA3 inactivation did not affect Th9-mediated tumour growth. Mechanistically, IL-9 controls claudin2/3 expression and T cell-derived IL-6 production in colorectal tumours. IL-6 abrogated the anti-proliferative effects of IL-9 in epithelial organoids in vivo. IL-9-producing Th9 cells expand in CRC and control IL-6 production by T cells.

CONCLUSIONS

IL-9 is a crucial regulator of tumour growth in colitis-associated neoplasias and emerges as potential target for therapy.

Effect of crosstalk between Th17 and Th9 cells on the activation of dermal vascular smooth muscle cells in systemic scleroderma and regulation of tanshinone IIA

BACKGROUND

To evaluate the effect of T-helper 17 (Th17) cells and Th9 cells on the activation of dermal vascular smooth muscle cells (DVSMCs) in systemic scleroderma (SSc) and regulation of tanshinone IIA.

METHODS

The expression of interleukin 17 receptor (IL-17R) and interleukin 9 receptor (IL-9R) in the skin of SSc patients was assessed by immunofluorescence. The expression of IL-9 and IL-9R mRNA in peripheral blood mononuclear cells (PBMCs) of SSc patients were detected by quantitative real-time polymerase chain reaction (qRT-PCR). The proportion of Th9 cells in PBMCs of SSc patients was sorted by flow cytometry. The effect of IL-9 on the differentiation of Th17 and IL-17 on that of Th9 was detected by flow cytometry. The proportion of Th9 and Th17 cells in SSc patients was detected by flow cytometry. The level of collagen I, III, α-SMA, IL-9R, IL-17R, JNK, P38, and ERK were analyzed using western blot (WB).

RESULTS

Th9 cells were highly expressed in SSc. IL-9 stimulated the differentiation of immature T cells into Th17 cells. IL-17 induced the differentiation of immature T cells into Th9 cells. Tanshinone IIA inhibited the differentiation of immature T lymphocytes into Th17 and Th9. WB showed that the combined action of IL-17 and IL-9 upregulated the inflammation and proliferation of DVSMCs. Anti-IL17, anti-IL9, and tanshinone IIA inhibited the functional activation of DVSMCs.

STUDY LIMITATIONS

For Th17, Th9 and vascular smooth muscle cells, the study on the signal pathway of their interaction is not thorough enough. More detailed studies are needed to explore the mechanism of cell-cell interaction.

CONCLUSIONS

The current results suggested that Th17 and Th9 cells induced the activation of DVSMCs in SSc through crosstalk in vitro, and tanshinone IIA inhibited the process.

Pattern Recognition Receptor Signaling and Cytokine Networks in Microbial Defenses and Regulation of Intestinal Barriers: Implications for Inflammatory Bowel Disease

Inflammatory bowel disease is characterized by defects in epithelial function and dysregulated inflammatory signaling by lamina propria mononuclear cells including macrophages and dendritic cells in response to microbiota. In this review, we focus on the role of pattern recognition receptors in the inflammatory response as well as epithelial barrier regulation. We explore cytokine networks that increase inflammation, regulate paracellular permeability, cause epithelial damage, up-regulate epithelial proliferation, and trigger restitutive processes. We focus on studies using patient samples as well as speculate on pathways that can be targeted to more holistically treat patients with inflammatory bowel disease.

IL-9 blockade attenuates inflammation in a murine model of mechanical ventilation-induced lung injury by inhibiting the NLRP3 inflammasome pathway

OBJECTIVES

Ventilation-induced lung injury (VILI) causes a huge economic and social burden, and its prevention and treatment have gained increasing attention in recent years. IL-9 is an important inflammatory factor, but its potential role in VILI remains unclear. This study intended to explore whether blocking IL-9 could alleviate VILI and explore its underlying mechanism.

METHODS

Lung injury was induced by mechanical ventilation (MV) in C57BL/6 mice. Changes in inflammatory factors and NLRP3-related proteins were assessed using quantitative reverse transcription-polymerase chain reaction, western blotting, and enzyme-linked immunosorbent assay. Subsequently, Nlrp3^-/- mice were used to further elucidate the underlying mechanism.

RESULTS

The percentage of Th9 cells in the peripheral blood, bronchoalveolar lavage fluid (BALF), and lung tissues of MV mice was increased compared to those of control mice. Treatment with anti-IL-9 mAb significantly alleviated the changes in lung histopathology, wet/dry lung proportion, total protein content, and neutrophil content in BALF induced by VILI. Additionally, administering anti-IL-9 mAb significantly downregulated the expression levels of inflammatory factors in BALF and lung tissues of mice with VILI. In addition, administering anti-IL-9 mAb inhibited NLRP3 inflammasome activation, as evidenced by the observed downregulation of NLRP3, ASC, cleaved caspase-1, and GSDMD-N. Additionally, NLRP3-deficient mice had lower lung injury induced by VILI than wild-type mice. Furthermore, the anti-IL-9 mAb only partially inhibited VILI in Nlrp3^-/- mice.

CONCLUSIONS

In MV mice, the anti-IL-9 mAb alleviated lung injury and reduced the secretion and expression of inflammatory factors partly by inhibiting the NLRP3 inflammasome pathway.

Network Pharmacology and Molecular Docking Analysis on Molecular Mechanism of Qingzi Zhitong Decoction in the Treatment of Ulcerative Colitis

Ulcerative colitis (UC) is a disease with complex pathological mechanisms. We explored the potential molecular mechanisms behind the therapeutic functions of Qingzi Zhitong decoction (QZZTD) in the treatment of UC by network pharmacology and molecular docking. QZZTD is a formula of Chinese traditional medicine consisting of 10 herbs. The potential active ingredients of QZZTD and their target genes were obtained from the Traditional Chinese Medicine Systems Pharmacology Database and Analysis Platform database, and UC-related target genes were obtained from GeneCards and OMIM databases. A total of 138 co-identified target genes were obtained by plotting the intersection target Venn diagram, and then the STRING database and Cytoscape software were used to establish protein-protein interaction networks and herb-ingredient-target networks. Four key active compounds and nine key proteins were identified. Then, Gene Ontology and Kyoto Encyclopedia of Genes and Genomes enrichment analyses showed that the biological functions of potential target genes were associated with DNA transcription, signaling receptor and ligand activity, cytokine activity, cellular autophagy, and antioxidant pathways, with related pathways involving the phosphatidylinositol 3-kinase (PI3K)-Akt signaling pathway, advanced glycosylation end product (AGE)-RAGE signaling pathway, tumor necrosis factor (TNF) signaling pathway, and IL-17 signaling pathway. Moreover, the binding activities of key target genes and essential active compounds of Chinese herbal medicines in QZZTD were further validated by molecular docking. This demonstrated that quercetin, luteolin, hyndarin, and beta-sitosterol had good binding to eight key proteins, and Akt1 was the target protein with the best binding activity, suggesting that Akt1 could be the essential mediator responsible for signaling transduction after QZZTD administration. The rat experiment verified that QZZTD inhibited PI3K-Akt pathway activation and reduced inflammation in UC. In conclusion, our study suggested four potential key active components, including quercetin, were identified in QZZTD, which could interact with Akt1 and modulate the activation of the PI3K-Akt pathway. The other three pathways may also be involved in the signaling transduction induced by QZZTD in the treatment of UC.

EPIDEMIOLOGIC ASPECTS OF INFLAMMATORY BOWEL DISEASE IN THE WESTERN REGION OF MINAS GERAIS STATE

BACKGROUND

Crohn's disease (CD) and ulcerative colitis (UC), two of the main inflammatory bowel diseases (IBD), have been increasingly diagnosed in South America. Although IBD have been intensively studied in the last years, epidemiologic data in Brazil are scarce.

OBJECTIVE

To study the clinical and epidemiologic profile of IBD patients treated in the Clinical Hospital of the Federal University of Uberlândia from 1999 to 2014.

METHODS

We performed a retrospective study of the medical records of patients diagnosed with IBD, according to the international classification of diseases (ICD) - ICD K50 for CD and ICD K51 for UC - confirmed by endoscopic examination in the case of both diseases. We analyzed the following variables: age; sex; ethnicity; smoking habit; primary diagnosis; site of disease manifestation; main clinical manifestations; IBD-related complications; extraintestinal manifestations; and established drug and/or surgical treatment.

RESULTS

We evaluated 183 IBD cases (91 UC and 92 CD cases). The estimated prevalence rate of UC was 15.06/100.000 inhabitants and of CD was 15.23/100.000. The CU and CD female to male incidence ratios were 1.7 and 1.8, respectively. The average age of patients diagnosed with UC was 39.4 years and of those diagnosed with CD was 31.1 years. White-skinned people were the most affected by UC (66.0%) and CD (69.0%). Few patients were submitted to surgical procedures as treatment alternative.

CONCLUSION

The estimated prevalence of IBD in this population was low compared to that of populations of North America, but high compared to that of other regions considered to present low incidence, such as some Asian and Latin American countries.

Do TRIB1 and IL-9 Gene Polymorphisms Impact the Development and Manifestation of Pituitary Adenoma?

BACKGROUND/AIM

To evaluate the association between TRIB1(rs6987702) and IL-9(rs1859430, rs2069870) genotypes with the development and manifestation of pituitary adenoma (PA).

MATERIALS AND METHODS

The study group included 141 patients with PA and the control group consisted of 287 healthy people. The genotyping of rs6987702, rs1859430 and rs2069870 was carried out using a real-time polymerase chain reaction.

RESULTS

Statistically significant results were obtained regarding the rs1859430, but there were no significant results regarding rs6987702. We found that the rs1859430 A/A genotype increased the odds of having recurrent PA six times (p=0.006) under the co-dominant model and four times (p=0.021) under the recessive model. Furthermore, the analysis showed that the G/A genotype increased the odds of having recurrent PA 2.3 times (p=0.003) under the co-dominant model, while G/A and A/A genotypes increased the odds 2.7 times (p=0.011) under the over-dominant model.

CONCLUSION

Certain genotypes of rs1859430 can be associated with PA recurrence.

Tumor necrosis factor ligand-related molecule 1A affects the intestinal mucosal barrier function by promoting Th9/interleukin-9 expression

Objectives

To investigate the effect of tumor necrosis factor ligand-related molecule 1A (TL1A) on the intestinal mucosal barrier in mice with chronic colitis.

Methods

Male TL1A-overexpressing transgenic mice and male C57BL/6 wild-type mice were used to establish a dextran sodium sulfate (DSS)-induced colitis model. The expression of occludin and claudin-1 was observed. Bacterial distribution in the intestinal mucosa and Th9/interleukin (IL)-9 expression were detected. In vitro co-culture systems of naive CD4⁺ T cells and Caco-2 cells were established and TL1A was added. Changes in transepithelial electrical resistance and IL-9 expression were measured. CD4+IL-9 cells were detected by flow cytometry.

Results

DSS mice showed a significant down-regulation of occludin and claudin-1 compared with controls. Expression levels of occludin, zonulin-1, and claudin-1 in the Caco-2+TGF-β+IL-4+TL1A group were significantly lower than in the Caco-2+TGF-β+IL-4 group. Bacterial distribution was clearly disordered in the DSS group. Transmembrane resistance of the Caco-2+TGF-β+IL-4+TL1A group was significantly lower and IL-9 expression significantly higher than in the Caco-2+TGF-β+IL-4 group.

Conclusions

TL1A overexpression promotes destruction of the intestinal mucosal barrier in mice with chronic colitis. The underlying mechanism may be associated with the promoting role of TL1A in Th9/IL-9 expression, which further destroys the mucosal barrier.

OX40L/OX40 Signal Promotes IL-9 Production by Mucosal MAIT Cells During Helicobacter pylori Infection

Mucosal associated invariant T (MAIT) cells play a critical role in Helicobacter pylori (H. pylori)-induced gastritis by promoting mucosal inflammation and aggravating mucosal injuries (1, 2). However, the underlying mechanism and key molecules involved are still uncertain. Here we identified OX40, a co-stimulatory molecule mainly expressed on T cells, as a critical regulator to promote proliferation and IL-9 production by MAIT cells and facilitate mucosal inflammation in H. pylori-positive gastritis patients. Serum examination revealed an increased level of IL-9 in gastritis patients. Meanwhile, OX40 expression was increased in mucosal MAIT cells, and its ligand OX40L was also up-regulated in mucosal dendritic cells (DCs) of gastritis patients, compared with healthy controls. Further results demonstrated that activation of the OX40/OX40L pathway promoted IL-9 production by MAIT cells, and MAIT cells displayed a highly-activated phenotype after the cross-linking of OX40 and OX40L. Moreover, the level of IL-9 produced by MAIT cells was positively correlated with inflammatory indexes in the gastric mucosa, suggesting the potential role of IL-9-producing MAIT cells in mucosal inflammation. Taken together, we elucidated that OX40/OX40L axis promoted mucosal MAIT cell proliferation and IL-9 production in H. pylori-induced gastritis, which may provide potential targeting strategies for gastritis treatment.

Th9 Cells in Peripheral Blood Increased in Patients with Immune-Related Pancytopenia

Background

Immune-related pancytopenia (IRP) is a kind of autoimmune disease mediated by autoantibodies in bone marrow. T helper 9 (Th9) cell is a new subset of T cell discovered recently, which mainly expresses cytokine interleukin-9 (IL-9) to exert immune function. Th9 cells are associated with a variety of inflammatory diseases, but the role of Th9 cells in IRP remains unclear.

Methods

Fifty patients with IRP and 20 healthy controls were enrolled. The percentage of Th9 cells was detected by flow cytometry (FCM) and ELISA. CD4⁺ lymphocytes were sorted by magnetic beads, and the mRNA expression levels of Th9 cells related transcription factors PU.1 and BATF were detected by RT-PCR.

Results

The percentage of Th9 cells in CD3⁺CD4⁺ cells was 2.73 ± 1.96% in the untreated group, which was significantly higher than those in the remission group (1.21 ± 0.86%) (p < 0.01) and the control group (0.68 ± 0.40%) (p < 0.001). And that in the remission group was significantly higher than that in the control group (p < 0.05). The level of IL-9 in the untreated group was 183.91 ± 112.42 pg/mL, which was significantly higher than that in the remission group (105.96 ± 64.79 pg/mL) (p < 0.01) and control group (56.03 ± 14.49 pg/mL) (p < 0.001). That in the remission group was also significantly higher than that in the control group (p < 0.01). They were negatively correlated with hemoglobin, red blood cell, white blood cell, and platelet counts and positively correlated with the percentage of CD19⁺B cells and CD5⁺CD19⁺/CD19⁺B cells, respectively. The mRNA expression levels of PU.1 and BATF in IRP patients were higher than those in controls (p < 0.05).

Conclusions

The percentage of Th9 cells in the peripheral blood and the level of IL-9 in the serum of patients with IRP were increased, which was related to the severity of the disease.

Advances in the role of helper T cells in autoimmune diseases

Autoimmune diseases are primary immune diseases in which autoreactive antibodies or sensitized lymphocytes destroy and damage tissue and cellular components, resulting in tissue damage and organ dysfunction. Helper T cells may be involved in the pathogenesis of autoimmune diseases under certain conditions. This review summarizes recent research on the role of helper T cells in autoimmune diseases from two aspects, helper T cell-mediated production of autoantibodies by B cells and helper T cell-induced activation of abnormal lymphocytes, and provides ideas for the treatment of autoimmune diseases. The abnormal expression of helper T cells promotes the differentiation of B cells that produce autoantibodies, which leads to the development of different diseases. Among them, abnormal expression of Th2 cells and T follicular helper cells is more likely to cause antibody-mediated autoimmune diseases. In addition, abnormal activation of helper T cells also mediates autoimmune diseases through the production of abnormal cytokines and chemokines. Helper T cells play an essential role in the pathogenesis of autoimmune diseases, and a full understanding of their role in autoimmune diseases is helpful for providing ideas for the treatment of autoimmune diseases.

Human "TH9" cells are a subpopulation of PPAR-γ+ TH2 cells

Although T_H1, T_H2, and T_H17 cells are well-defined T_H cell lineages in humans, it remains debated whether IL-9-producing T_H cells represent a bona fide "T_H9" lineage. Our understanding of the cellular characteristics and functions of IL-9-producing T_H cells in humans is still nascent. Here, we report that human IL-9-producing T_H cells express the chemokine receptors CCR4 and CCR8, produce high levels of IL-5 and IL-13, and express T_H2 lineage-associated transcription factors. In these cells, IL-9 production is activation dependent, transient, and accompanied by down-regulation of T_H2 cytokines, leading to an apparent "T_H9" phenotype. IL-9⁺ T_H2 cells can be distinguished from "conventional" T_H2 cells based on their expression of the transcription factor PPAR-γ. Accordingly, PPAR-γ is induced in naïve T_H cells by priming with IL-4 and TGF-β ("T_H9" priming) and is required for IL-9 production. In line with their identity as early activated T_H2 cells, IL-9⁺ T_H2 cells are found in acute allergic skin inflammation in humans. We propose that IL-9-producing T_H cells are a phenotypically and functionally distinct subpopulation of T_H2 cells that depend on PPAR-γ for full effector functions.

A new target for the treatment of inflammatory bowel disease: Interleukin-37

Interleukin (IL)-37 belongs to the IL-1 cytokine family. It has anti-inflammatory effects on numerous autoimmune diseases such as asthma, psoriasis, inflammatory bowel disease (IBD), systemic lupus erythematosus (SLE), multiple sclerosis (MS) and rheumatoid arthritis (RA). Mechanistically, IL-37 plays an anti-inflammatory role by regulating the expression of inflammatory factors in two ways: binding extracellular receptors IL-18R or transferring into the nucleus with Smad3. IBD is a kind of idiopathic intestinal inflammatory disease with unknown etiology and pathogenesis. Recent researches had proved that IL-37 is negatively involved in the pathogenesis and development of IBD. Among various inflammatory diseases, IL-37 has been shown to regulate inflammatory development by acting on various immune cells such as neutrophils, macrophages (Mϕ), dendritic cells (DCs), T cells and intestinal epithelial cells. This review summarizes the biological role of IL-37, and its immunoregulatory effects on the immune cells, especially anti-inflammatory function in both human and experimental models of IBD.

IL-9 exerts biological function on antigen-experienced murine T cells and exacerbates colitis induced by adoptive transfer

IL-9 is involved in various T cell-dependent inflammatory models including colitis, encepahlitis, and asthma. However, the regulation and specificity of IL-9 responsiveness by T cells during immune responses remains poorly understood. Here, we addressed this question using two different models: experimental colitis induced by transfer of naive CD4⁺ CD45RB^high T cells into immunodeficient mice, and OVA-specific T cell activation. In the colitis model, constitutive IL-9 expression exacerbated inflammation upon transfer of CD4⁺ CD45RB^high T cells from WT but not from Il9r^-/- mice, indicating that IL-9 acts directly on T cells. Suprisingly, such naïve CD4⁺ CD45RB^high T cells failed to express the Il9r or respond to IL-9 in vitro, in contrast with CD4⁺ CD45RB^low T cells. By using OVA-specific T cells, we observed that T cells acquired the capacity to respond to IL-9 along with CD44 upregulation, after long-lasting (5 to 12 days) in vivo antigenic stimulation. Il9r expression was associated with Th2 and Th17 phenotypes. Interestingly, in contrast to the IL-2 response, antigen restimulation downregulated IL-9 responsiveness. Taken together, our results demonstrate that IL-9 does not act on naïve T cells but that IL-9 responsiveness is acquired by CD4⁺ T cells after in vivo activation and acquisition of memory markers such as CD44.

Significance of TC9 and TH9 in Helicobacter pylori-induced gastritis

BACKGROUND

H pylori plays a critical role in the development of stomach cancer, especially in people affected by the bacteria at an early stage of life. Th9 cells and IL-9 play major roles in immune responses against various infections. IL-9 is influential in chronic or acute inflammation of the mucosa.

AIM

This study seeks to investigate the possible functions of Tc9, Th9 cells, and IL-9 level in patients with inflammation due to H pylori infection.

METHODS

Eighty-three patients with dyspepsia symptoms and twenty normal subjects with no sign and symptoms of dyspepsia were recruited. Frequencies of T-cell subsets were determined by flow cytometry. Levels of cytokines IL-9 family in the sera and supernatants of antigen-activated PBMCs patients were measured by ELISA and flow cytometry.

RESULTS

The participants included 56 females and 47 males with a mean age of 39.2 ± 15.3 years. We assigned the infected group into peptic ulcer and gastritis (chronic active and chronic). Frequencies of Tc9, Th17, Tc17, Th17/9, and Tc17/9 increased significantly in the peptic ulcer, chronic active, and chronic gastritis, compared with the uninfected and healthy control groups. A significant increase was seen in IL-9, IL-4, and IL-23 in the chronic active gastritis. Further observed was a significant increase in IL-21 and a decrease in IL-10 in the infected groups.

CONCLUSION

The results revealed that increased Tc9, Th17/9, and Tc17/9 cells appear to be influential in the progression and severity of H pylori infection. Also, increased IL-9 and IL-4 levels and Tc9, Tc17/9, and Th17/9 were seen in chronic active gastritis patients. These findings may provide useful information for a therapeutic targeting of chronic active H pylori infections.

Protective effect of Saccharomyces boulardii on intestinal mucosal barrier of dextran sodium sulfate-induced colitis in mice

Background:

The effect and mechanism of Saccharomyces boulardii (Sb) in inflammatory bowel disease are unclear. The objective of the study was to evaluate the impact of Sb on intestinal mucosal barrier and intestinal flora in a colitis mouse model.

Methods:

Forty C57BL/6J male mice were randomly assigned to five groups: normal control group (A), pathologic control group (B), Sb treatment group (C), mesalazine treatment group (D), and Sb combined with mesalazine treatment group (E). Colitis was induced by the addition of 2.5% (wt/vol) dextran sodium sulfate (DSS) in the drinking water ad libitum for 7 days. The general condition, weight change, stool property, and bloody stool level of mice were observed to evaluate the disease activity index. The expression of zona occludens-1 (ZO-1) and occludin in intestinal tissue were measured by immunohistochemistry. The level of tumor necrosis factor-α (TNF-α) and interleukin (IL)-8 in plasma was measured by enzyme linked immunosorbent assay. Inter-cellular tight junctions were observed by transmission electron microscopy. The feces and intestinal contents were collected sterilely, and intestinal flora was analyzed by 16S rRNA sequencing.

Results:

Compared with group B, Sb reduced the disease activity index and histological score of group C (disease activity index: group B 2.708 ± 0.628, group C 1.542 ± 0.616, P_BC = 0.005; histological score: group B 9.875 ± 3.271, group C 4.750 ± 1.832, P_BC = 0.005) in DSS-induced colitis in mice. Sb exerted a protect effect on the expression of ZO-1 (group B 2.075 ± 1.176, group C 4.225 ± 1.316, P_BC = 0.019) and occludin (group B 2.200 ± 0.968, group C 3.525 ± 1.047, P_BC = 0.023). Compared with group B, Sb decreased the level of TNF-α and IL-8 of group C (TNF-α: group B 716.323 ± 44.691 ng/L, group C 521.740 ± 90.121 ng/L, P_BC = 0.001; IL-8: group B 128.992 ± 11.475 pg/mL, group C 106.283 ± 15.906 pg/mL, P_BC = 0.012). Treatment with Sb preserved the tight junctions and ameliorated microvilli and inter-cellular space. Treatment with Sb also showed its own characteristics: a higher percentage of Bacteroidetes and a lower percentage of Firmicutes, with significant differences or a significant trend. The proportion of the S24-7 family was increased significantly in the Sb treatment group.

Conclusions:

Sb shows an anti-inflammatory effect and has a protective effect on the intestinal mucosal mechanical barrier. Sb may up-regulate the abundance of family S24-7 specifically, and maybe a mechanism underlying its function.

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.

•

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

•

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

•

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

•

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.

The role of integrins in the pathogenesis of inflammatory bowel disease: Approved and investigational anti-integrin therapies

Inflammatory bowel disease (IBD) is characterized by uncontrolled inflammation in the gastrointestinal tract. The underlying pathobiology of IBD includes an increase in infiltrating gut-homing lymphocytes. Although lymphocyte homing is typically a tightly regulated and stepwise process involving multiple integrins and adhesion molecules expressed on endothelial cells, the distinct roles of integrin-expressing immune cells is not fully understood in the pathology of IBD. In this review, we detail the involvement of integrins expressed on specific lymphocyte subsets in the pathogenesis of IBD and discuss the current status of approved and investigational integrin-targeted therapies.

TL1A modulates the severity of colitis by promoting Th9 differentiation and IL-9 secretion

AIMS

TL1A was reported to contribute to the susceptibility to ulcerative colitis (UC). However, the molecular mechanisms of TL1A in UC development are poorly understood. We aimed to investigate the role of TL1A in colitis, and reveal the regulatory mechanism of TL1A in chronic colitis development.

MAIN METHODS

Wild-type mice and transgenic mice with overexpressing TL1A in lymphocytes were used to construct chronic DSS colitis models. To investigate the molecular mechanism in vitro, CD4⁺ T cells were sorted from spleens and mesenteric lymph node cells to induce Th9 cells. Biopsy specimens from ulcerative colitis patients were collected for in vivo validation.

KEY FINDINGS

The elevated TL1A expression in chronic DSS colitis models exacerbated intestinal inflammation. The differentiation of Th9 cells, IL-9 secretion and production of TGF-β, IL-4 and PU.1 was significantly enhanced in transgenic mice with TL1A overexpression. In vitro results showed that TL1A enhanced the Th9 cells, IL-9 and PU.1 production, while TL1A antibodies inhibited their production. In human translational studies, patients with ulcerative colitis with elevated TL1A expression also exhibited more serious inflammation with higher levels of Th9 cells, IL-9 and PU.1 expression.

SIGNIFICANCE

We presented a possible mechanism of TL1A in UC development that TL1A may promote the differentiation of Th9 cells and enhanced IL-9 secretion by up-regulating the expression of TGF-β, IL-4 and PU.1, which provided a novel perspective to study the UC pathogenesis, and indicated that targeting of TL1A signal pathway may by a likely strategy for the treatment of chronic colitis.

Oligonucleotides-A Novel Promising Therapeutic Option for IBD

Inflammatory Bowel Diseases (IBD), whose denomination comprehends Crohn's Disease (CD) and Ulcerative Colitis (UC), are intestinal chronic diseases that often require lifelong medical therapy. In the last two decades monoclonal antibodies against the cytokine TNF have become integral parts in the treatment of IBD patients, however there are unwanted side-effects and one third of patients show primary non-response while another subgroup loses response over time. Finding novel drugs which could act as therapies against precise pro-inflammatory molecular targets to avoid unwanted systemic side effects and additionally the process of immunization, represents an important aim for subsequent therapeutic approaches. Oligonucleotide based therapies represent a promising novel concept for the treatment of IBD. The molecular action of oligonucleotides ranges from inhibition of the translational process of mRNA transcripts of pro-inflammatory molecules, to mimicking bacterial DNA which can activate cellular targets for immunomodulation. Alicaforsen, selectively targets ICAM-1 mRNA. ICAM-1 is an adhesion molecule which is upregulated on endothelial cells during IBD, thereby mediating the adhesion and migration of leucocytes from blood to sites of active inflammation. In CD parenteral application of alicaforsen did not show therapeutic efficacy in phase II trials, but it demonstrated an improved efficacy as a topical enema in distal UC. Topical application of alicaforsen might represent a therapeutic perspective for refractory pouchitis as well. SMAD7 is a protein that inhibits the signaling of TGFβ, which is the mainstay of a regulatory counterpart in cellular immune responses. An antisense oligonucleotide against SMAD7 mRNA (mongersen) demonstrated pre-clinical and phase II efficacy in CD, but a phase III clinical trial was stopped due to lack of efficacy. Cobitolimod is a single strand oligonucleotide, which mimics bacterial DNA as its CpG dinucleotide sequences can be recognized by the Toll-like receptor 9 on different immune cells thereby causing induction of different cytokines, for example IL10 and IFNα. Topical application of cobitolimod was studied in UC patients. We will also discuss two other novel oligonucleotides which act on the GATA3 transcription factor (SB012) and on carbohydrate sulfotransferase 15 (STNM01), which could both represent novel promising therapeutic options for the treatment of UC.

What can primary immunodeficiencies teach us about Th9 cell differentiation and function?

Interleukin-9 (IL-9) producing CD4⁺ Th9 cells are a unique subset of effector cells involved in both health and disease. Th9 cells have been associated with protective immunity during parasitic infections with helminths, protozoans and extracellular pathogens, but implicated in disease states such as allergic asthma, atopic dermatitis, food allergy and autoimmune conditions including multiple sclerosis and ulcerative colitis. Here, we review the cytokine signaling pathways and downstream transcription factors required for IL-9 expression and how human primary immunodeficiencies caused by monogenic mutations can help elucidate the complex requirements for human Th9 cell differentiation. Primary immunodeficiencies are a platform for investigating IL-9 expression in primary human lymphocytes and by inference whether Th9 cells are implicated in the clinical phenotype characteristic of these patients.

Lentiviral vector-mediated IL-9 overexpression stimulates cell proliferation by targeting c-myc and cyclin D1 in colitis-associated cancer

Colorectal cancer caused by inflammatory bowel disease is referred as colitis-associated cancer (CAC). The mechanism underling CAC is not fully understood. In the present study, the role of interleukin-9 (IL-9) in CAC was examined. The current study included 12 colorectal tissue specimens and matched adjacent tissues from CAC. The expression of IL-9 protein was examined using immunohistochemical staining. The expression of IL-9 in cancer tissues was markedly higher compared with that in adjacent tissues. Furthermore, IL-9 gene overexpression lentiviral vectors were constructed to overexpress IL-9 in RKO and Caco-2 cell lines. The role of IL-9 in cell proliferation was investigated using a Cell Counting Kit-8 assay, and MYC proto-oncogene bHLH transcription factor (c-Myc) and cyclinD1 expression levels were detected by reverse transcription-quantitative polymerase chain reaction. Notably, IL-9 overexpression promoted the proliferation of colonic epithelial cells by upregulating of the expression of c-Myc and cyclinD1. In conclusion, the present results suggested that IL-9 may exhibit an essential role in the pathogenesis of CAC, and IL-9 promotes the proliferation of colonic epithelial RKO and Caco2 cells, partially via the upregulation of c-Myc and cyclinD1 expression.

Th9 lymphocytes and functions of interleukin 9 with the focus on IBD pathology

The work presents the newest knowledge on a new phenotype of T helper lymphocytes (Th9) and on Interleukin 9 (IL-9). Processes leading to transformation of naïve T lymphocyte into Th9 lymphocytes are presented, including the role of IL-4 and TGFβ signaling. Involvement of transcription factor network in production of IL-9 is described. Other cells capable of expressing IL-9 and secreting IL-9 are portrayed. Diversity of IL-9 effects caused by activation of IL-9 receptors on various types of cells is presented. Principal effects of the activation of IL-9 receptor on T-cells seem to be antiapoptotic and stimulatory which leads to enhanced defense against parasitic infection and cancer development but, from the other side, it perpetuate chronic inflammation in autoimmune diseases and allergic processes. In the last years the role of IL-9 in autoimmune diseases such as rheumatic diseases and inflammatory bowel disease gained importance since the increased expression of this cytokine has been observed in animal models of intestinal inflammation and in groups of patients with ulcerative colitis. It was also noted that neutralization of IL-9 in animal models of ulcerative colitis leads to amelioration of inflammatory process, what could have significance in the treatment of this disease in humans in the future.

Is Curcumin a Possibility to Treat Inflammatory Bowel Diseases?

The inflammatory bowel diseases (IBDs) are mainly represented by Crohn's disease and Ulcerative colitis that are characterized by chronic and relapsing inflammatory processes of the gastrointestinal system. Curcuma longa L. is a plant with several medicinal properties, including anti-inflammatory effects, and curcumin is the most important compound derived from its rhizomes. As curcumin has remarkable anti-inflammatory actions, the aim of this work is to review the potential use of this compound in IBD patients. We consulted MEDLINE (PubMed/PMC), and the literature search was performed with the following combinations of terms "Inflammatory Bowel Diseases" and "Curcumin," "Crohn's Disease" and "Curcumin," "Ulcerative colitis" and "Curcumin." The inclusion criteria were articles that showed original studies with human models and the exclusion criteria were not full-text articles, articles not in English, poster presentations, letters, editorials, and articles not available. Curcumin interacts with receptors, growth and transcription factors, cytokines, enzymes, and genes leading to inhibitory effects on cyclooxygenase-1, tumor necrosis factor-α, interferon-γ, inducible nitric oxide synthase, transcriptional nuclear factor kappa B, and many other molecules associated with inflammatory processes. These molecules are critical factors in the positive regulation of inflammatory cytokines in inflammatory diseases, suggesting that curcumin may be considered as a new therapeutic agent for patients with IBD. Curcumin is a natural anti-inflammatory agent that represents an attractive, safe and inexpensive alternative for the treatment of IBD. Nevertheless, it is necessary to know the efficient and safe dose and consider its poor absorption.

A Decade of Th9 Cells: Role of Th9 Cells in Inflammatory Bowel Disease

T helper cell subsets play a critical role in providing protection against offending pathogens by secreting specific cytokines. However, unrestrained T helper cell responses can promote chronic inflammation-mediated inflammatory diseases. Dysregulated T helper cell responses have been suggested to be involved in the pathogenesis of multiple inflammatory diseases, including allergic airway inflammation, rheumatoid arthritis, and inflammatory bowel disease (IBD) among others. Aberrant pro-inflammatory responses induced by Th1, Th2, and Th17 subsets are known to trigger IBD. IBD is a chronic inflammatory disease characterized by weight loss, diarrhea, pain, fever, and rectal bleeding. It poses a major health burden worldwide owing to the increased risk of colorectal cancer development. Despite numerous therapeutic advancements, IBD still remains a major health burden due to the inefficiency of the conventional therapies. Recently, IL-9-secreting Th9 cells are known to be involved in the pathogenesis of IBD. However, the role of Th9 cells and their secretory cytokine IL-9 in IBD is unclear. The functional relevance of Th9 cells is also relatively understudied in IBD. Thus, investigating the actual role of various T helper cell subsets including Th9 cells in IBD is essential to develop novel therapies to treat IBD. Here, we highlight the role of Th9 cells in promoting IBD. We discuss the mechanisms that might be employed by Th9 cells and IL-9 in promoting IBD and thereby propose potential targets for the treatment of Th9 cell-mediated IBD.

Immunopathogenesis of inflammatory bowel disease and mechanisms of biological therapies

Inflammatory bowel disease (IBD) is a chronic inflammatory disorder of the gastrointestinal tract with a multifactorial pathophysiology. Full comprehension of IBD pathology is still out of reach and, therefore, treatment is far from ideal. Nevertheless, components involved in IBD pathogenesis including environmental, genetic, microbial, and immunological factors are continuously being investigated and the improved knowledge contributes to the development of new therapies. In this article we review the aspects of the immunopathogenesis of IBD, with focus on mucosal immunity, and discuss mechanisms of action for current and emerging biological therapies.

Old and New Lymphocyte Players in Inflammatory Bowel Disease

Inflammatory bowel disease (IBD), encompassing Crohn's disease and ulcerative colitis, is a chronic intestinal inflammatory disorder characterized by diffuse accumulation of lymphocytes in the gut mucosa as a consequence of over-expression of endothelial adhesion molecules. The infiltrating lymphocytes have been identified as subsets of T cells, including T helper (Th)1 cells, Th17 cells, and regulatory T cells. The function of these lymphocyte subpopulations in the development of IBD is well-known, since they produce a number of pro-inflammatory cytokines, such as interferon-γ and interleukin-17A, which in turn activate mucosal proteases, thus leading to the development of intestinal lesions, i.e., ulcers, fistulas, abscesses, and strictures. However, the immune mechanisms underlying IBD are not yet fully understood, and knowledge about the function of newly discovered lymphocytes, including Th9 cells, innate lymphoid cells, mucosal-associated invariant T cells, and natural killer T cells, might add new pieces to the complex puzzle of IBD pathogenesis. This review summarizes the recent advances in the understanding of the role of mucosal lymphocytes in chronic intestinal inflammation and deals with the therapeutic potential of lymphocyte-targeting drugs in IBD patients.

The Intricate Link among Gut "Immunological Niche," Microbiota, and Xenobiotics in Intestinal Pathology

Inflammatory bowel diseases (IBDs) are diseases characterized by various degrees of inflammation involving the gastrointestinal tract. Ulcerative colitis and Crohn's disease are characterized by a dysregulated immune response leading to structural gut alterations in genetically predisposed individuals. Diverticular disease is characterized by abnormal immune response to normal gut microbiota. IBDs are linked to a lack of physiological tolerance of the mucosal immune system to resident gut microbiota and pathogens. The disruption of immune tolerance involves inflammatory pathways characterized by an unbalance between the anti-inflammatory regulatory T cells and the proinflammatory Th1/Th17 cells. The interaction among T cell subpopulations and their related cytokines, mediators of inflammation, gut microbiota, and the intestinal mucosa constitute the gut “immunological niche.” Several evidences have shown that xenobiotics, such as rifaximin, can positively modulate the inflammatory pathways at the site of gut immunological niche, acting as anti-inflammatory agents. Xenobiotics may interfere with components of the immunological niche, leading to activation of anti-inflammatory pathways and inhibition of several mediators of inflammation. In summary, xenobiotics may reduce disease-related gut mucosal alterations and clinical symptoms. Studying the complex interplay between gut immunological niche and xenobiotics will certainly open new horizons in the knowledge and therapy of intestinal pathologies.

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.

Systemic interleukin-9 in inflammatory bowel disease: Association with mucosal healing in ulcerative colitis

AIM

To evaluate circulating IL9 in inflammatory bowel disease and disease-associated anemia/cachexia and assess its potential as a mucosal healing marker.

METHODS

Serum IL9 as well as other cytokines (IL1β, IL6, IL13, IFNγ, TNFα, and VEGF-A) were determined in 293 individuals: 97 patients with Crohn’s disease (CD) and 74 with ulcerative colitis (UC) and in 122 apparently healthy controls. The clinical activity of CD and UC was expressed in terms of the Crohn’s Disease Activity Index (CDAI) and the Mayo Scoring System (MDAI), respectively, and the severity of bowel inflammation in UC patients was assessed using Mayo endoscopic score. Cytokine concentrations were measured by a flow cytometry-based method using Luminex xMAP^® technology. High-sensitive C-reactive protein concentrations (hsCRP) were determined in CD and UC patients using the enhanced immunoturbidimetric method.

RESULTS

Systemic IL9 was significantly lower in healthy individuals [9 pg/mL (95%CI: 8.2-10)] than in patients with inflammatory bowel disease (IBD): both inactive [14.3 pg/mL (11.9-19.9)] and active [27.6 pg/mL (24.5-32), P < 0.0001]. Cytokine concentrations were significantly higher in active CD [27.4 pg/mL (23.4-32.2)] and in active UC [32.7 pg/mL (27-38.9)] compared to inactive diseases [15.9 pg/mL (10.8-23.4) in CD and 19.4 pg/mL (13.9-27.1) in UC, P = 0.001]. IL9 correlated weakly with CDAI (ρ = 0.32, P = 0.003) and MDAI (ρ = 0.35, P = 0.002) and strongly with endoscopic inflammation in UC (ρ = 0.74, P < 0.0001). As a negative marker of mucosal healing (MH), IL9 had an accuracy superior to hsCRP and IL6 [97% (P < 0.0001), 67% (P = 0.071), and 55% (P = 0.525), respectively]. IL9 was significantly higher in cachectic IBD patients [30.25 pg/mL (24.4-37.5) vs 21.88 pg/mL (18-26.5), P = 0.026] and negatively correlated with hemoglobin concentrations (ρ = -0.27, P < 0.001). Multiple regression showed IL1β and IL13 to be the independent predictors of circulating IL9 in healthy individuals, IFNγ or IL6 in active and inactive UC, respectively, and IL13 and VEGF-A in both active and inactive CD.

CONCLUSION

The systemic IL9 level is higher in IBD and corresponds with endoscopic inflammation, suggesting its possible application as a negative marker of mucosal healing in UC.