TH9 cells that express the transcription factor PU.1 drive T cell-mediated colitis via IL-9 receptor signaling in intestinal epithelial cells. Nat Immunol. 2014;15:676-686. [PMID: 24908389 DOI: 10.1038/ni.2920]

A comprehensive immunobiology review of IBD: With a specific glance to Th22 lymphocytes development, biology, function, and role in IBD

The two primary forms of inflammatory disorders of the small intestine andcolon that make up inflammatory bowel disease (IBD) are ulcerative colitis (UC) and Crohn's disease (CD). While ulcerative colitis primarily affects the colon and the rectum, CD affects the small and large intestines, as well as the esophagus,mouth, anus, andstomach. Although the etiology of IBD is not completely clear, and there are many unknowns about it, the development, progression, and recurrence of IBD are significantly influenced by the activity of immune system cells, particularly lymphocytes, given that the disease is primarily caused by the immune system stimulation and activation against gastrointestinal (GI) tract components due to the inflammation caused by environmental factors such as viral or bacterial infections, etc. in genetically predisposed individuals. Maintaining homeostasis and the integrity of the mucosal barrier are critical in stopping the development of IBD. Specific immune system cells and the quantity of secretory mucus and microbiome are vital in maintaining this stability. Th22 cells are helper T lymphocyte subtypes that are particularly important for maintaining the integrity and equilibrium of the mucosal barrier. This review discusses the most recent research on these cells' biology, function, and evolution and their involvement in IBD.

Protective effects of ginsenosides on ulcerative colitis: a meta-analysis and systematic review to reveal the mechanisms of action

BACKGROUND

Ulcerative colitis (UC) is a chronic inflammatory disease of the colon. Ginsenoside may be an ideal agent for UC treatment. However, its efficacy and safety are unknown. We aim to conduct a systematic evaluation to assess the effects and potential mechanisms of ginsenosides in animal models of UC.

METHODS

Six electronic databases will be searched (PubMed, Embase, Web of Science, China Knowledge Network (CNKI), China Science and Technology Journal Database (CQVIP), and Wanfang Data Knowledge). SYRCLE list will be used to assess the quality of literature, and STATA 15.1 for data analysis. Time-dose effects analysis will be used to reveal the time-dosage response relations between ginsenosides and UC.

RESULTS

Ultimately, fifteen studies involving 300 animals were included. Preliminary evidence was shown that ginsenosides could reduce Disease Activity Index (DAI) scores, weight loss, histological colitis score (HCS), spleen weight, Malondialdehyde (MDA), Myeloperoxidase (MPO) activity, interleukin-1β (IL-1β), interleukin 6 (IL-6), tumor necrosis factor α (TNF-α) and increase colon length (CL), myeloperoxidase (GSH), interleukin 4 (IL-4), interleukin 10 (IL-10), Zonula Occludens-1 (ZO-1) and occludin. Results of time-dose interval analysis indicated that ginsenosides at a dosage of 5-200 mg/kg with an intervention time of 7-28 days were relatively effective.

CONCLUSIONS

Preclinical evidence suggests that ginsenoside is a novel treatment for UC. And the mechanisms of ginsenosides in treating UC may involve anti-inflammatory, antioxidant, barrier protection, intestinal flora regulation, and immune regulation. Although, due to the high heterogeneity, further large-scale and high-quality preclinical studies are needed to examine the protection of ginsenosides against UC.

The emerging role of T helper 9 (Th9) cells in immunopathophysiology: A comprehensive review of their effects and responsiveness in various disease states

Th9 cells, a subset of T-helper cells producing interleukin-9 (IL-9), play a vital role in the adaptive immune response and have diverse effects in different diseases. Regulated by transcription factors like PU.1 and IRF4, and cytokines such as IL-4 and TGF-β, Th9 cells drive tissue inflammation. This review focuses on their emerging role in immunopathophysiology. Th9 cells exhibit immune-mediated cancer cell destruction, showing promise in glioma and cervical cancer treatment. However, their role in breast and lung cancer is intricate, requiring a deeper understanding of pro- and anti-tumor aspects. Th9 cells, along with IL-9, foster T cell and immune cell proliferation, contributing to autoimmune disorders. They are implicated in psoriasis, atopic dermatitis, and infections. In allergic reactions and asthma, Th9 cells fuel pro-inflammatory responses. Targeting Foxo1 may regulate innate and adaptive immune responses, alleviating disease symptoms. This comprehensive review outlines Th9 cells' evolving immunopathophysiological role, emphasizing the necessity for further research to grasp their effects and potential therapeutic applications across diseases.

Locus of (IL-9) control: IL9 epigenetic regulation in cellular function and human disease

Interleukin-9 (IL-9) is a multifunctional cytokine with roles in a broad cross-section of human diseases. Like many cytokines, IL-9 is transcriptionally regulated by a group of noncoding regulatory elements (REs) surrounding the IL9 gene. These REs modulate IL-9 transcription by forming 3D loops that recruit transcriptional machinery. IL-9-promoting transcription factors (TFs) can bind REs to increase locus accessibility and permit chromatin looping, or they can be recruited to already accessible chromatin to promote transcription. Ample mechanistic and genome-wide association studies implicate this interplay between IL-9-modulating TFs and IL9 cis-REs in human physiology, homeostasis, and disease.

How the Western Diet Thwarts the Epigenetic Efforts of Gut Microbes in Ulcerative Colitis and Its Association with Colorectal Cancer

Ulcerative colitis (UC) is an autoimmune disease in which the immune system attacks the colon, leading to ulcer development, loss of colon function, and bloody diarrhea. The human gut ecosystem consists of almost 2000 different species of bacteria, forming a bioreactor fueled by dietary micronutrients to produce bioreactive compounds, which are absorbed by our body and signal to distant organs. Studies have shown that the Western diet, with fewer short-chain fatty acids (SCFAs), can alter the gut microbiome composition and cause the host's epigenetic reprogramming. Additionally, overproduction of H2S from the gut microbiome due to changes in diet patterns can further activate pro-inflammatory signaling pathways in UC. This review discusses how the Western diet affects the microbiome's function and alters the host's physiological homeostasis and susceptibility to UC. This article also covers the epidemiology, prognosis, pathophysiology, and current treatment strategies for UC, and how they are linked to colorectal cancer.

Current understanding of the interplay between extracellular matrix remodelling and gut permeability in health and disease

The intestinal wall represents an interactive network regulated by the intestinal epithelium, extracellular matrix (ECM) and mesenchymal compartment. Under healthy physiological conditions, the epithelium undergoes constant renewal and forms an integral and selective barrier. Following damage, the healthy epithelium is restored via a series of signalling pathways that result in remodelling of the scaffolding tissue through finely-regulated proteolysis of the ECM by proteases such as matrix metalloproteinases (MMPs). However, chronic inflammation of the gastrointestinal tract, as occurs in Inflammatory Bowel Disease (IBD), is associated with prolonged disruption of the epithelial barrier and persistent damage to the intestinal mucosa. Increased barrier permeability exhibits distinctive signatures of inflammatory, immunological and ECM components, accompanied by increased ECM proteolytic activity. This narrative review aims to bring together the current knowledge of the interplay between gut barrier, immune and ECM features in health and disease, discussing the role of barrier permeability as a discriminant between homoeostasis and IBD.

Emerging role of gut microbiota in autoimmune diseases

Accumulating studies have indicated that the gut microbiota plays a pivotal role in the onset of autoimmune diseases by engaging in complex interactions with the host. This review aims to provide a comprehensive overview of the existing literatures concerning the relationship between the gut microbiota and autoimmune diseases, shedding light on the complex interplay between the gut microbiota, the host and the immune system. Furthermore, we aim to summarize the impacts and potential mechanisms that underlie the interactions between the gut microbiota and the host in autoimmune diseases, primarily focusing on systemic lupus erythematosus, rheumatoid arthritis, Sjögren's syndrome, type 1 diabetes mellitus, ulcerative colitis and psoriasis. The present review will emphasize the clinical significance and potential applications of interventions based on the gut microbiota as innovative adjunctive therapies for autoimmune diseases.

Role of LINC00240 on T-helper 9 differentiation in allergic rhinitis through influencing DNMT1-dependent methylation of PU.1

BACKGROUND

Allergic rhinitis (AR) is a common allergic disease with increasing prevalence globally. However, the molecular mechanism underlying AR pathogenesis remains largely undefined.

METHODS

Peripheral blood and nasal mucosa samples obtained from patients with AR (n = 22), and ovalbumin-induced AR mouse model (n = 8 per group) were prepared for subsequent detection. qRT-PCR and western blot were used to detect the expression of LINC00240, miR-155-5p, PU.1 and other key molecules. ELISA assay and flow cytometry were employed to evaluate the secretion of IL-9 and T-helper 9 (Th9) cell ratio, respectively. Bioinformatics analysis, RNA immunoprecipitation (RIP), chromatin immunoprecipitation (ChIP) and luciferase reporter assays were employed to further elucidate the regulatory network of LINC00240/miR-155-5p/DNMT1. The methylation of PU.1 promoter was assessed by methylation-specific PCR (MSP). This signaling axis was further validated in the mouse model of AR.

RESULTS

LINC00240 was downregulated, while miR-155-5p and PU.1 were upregulated in the peripheral blood and nasal mucosa of AR patients, as well as in AR mice. This was accompanied with the increased ratio of Th9 cells and elevated IL-9 secretion. Mechanistically, LINC00240 served as a miR-155-5p sponge, and DNMT1 was a target of miR-155-5p. In addition, DNMT1 mediated the methylation of PU.1 promoter. In vivo studies verified that LINC00240 mitigated AR progression, possibly via miR-155-5p/DNMT1/PU.1-dependent Th9 differentiation.

CONCLUSION

The involvement of LINC00240 in AR pathogenesis is closely associated with Th9 differentiation through modulating DNMT1-dependent methylation of PU.1 by sponging miR-155-5p.

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.

TXA2 attenuates allergic lung inflammation through regulation of Th2, Th9, and Treg differentiation

In lung, thromboxane A2 (TXA2) activates the TP receptor to induce proinflammatory and bronchoconstrictor effects. Thus, TP receptor antagonists and TXA2 synthase inhibitors have been tested as potential asthma therapeutics in humans. Th9 cells play key roles in asthma and regulate the lung immune response to allergens. Herein, we found that TXA2 reduces Th9 cell differentiation during allergic lung inflammation. Th9 cells were decreased approximately 2-fold and airway hyperresponsiveness was attenuated in lungs of allergic mice treated with TXA2. Naive CD4+ T cell differentiation to Th9 cells and IL-9 production were inhibited dose-dependently by TXA2 in vitro. TP receptor-deficient mice had an approximately 2-fold increase in numbers of Th9 cells in lungs in vivo after OVA exposure compared with wild-type mice. Naive CD4+ T cells from TP-deficient mice exhibited increased Th9 cell differentiation and IL-9 production in vitro compared with CD4+ T cells from wild-type mice. TXA2 also suppressed Th2 and enhanced Treg differentiation both in vitro and in vivo. Thus, in contrast to its acute, proinflammatory effects, TXA2 also has longer-lasting immunosuppressive effects that attenuate the Th9 differentiation that drives asthma progression. These findings may explain the paradoxical failure of anti-thromboxane therapies in the treatment of asthma.

Regulatory role of T helper 9/interleukin-9: Transplantation view

T helper 9 (Th9) cells, a subset of CD4+ T helper cells, have emerged as a valuable target for immune cell therapy due to their potential to induce immunomodulation and tolerance. The Th9 cells mainly produce interleukin (IL)-9 and are known for their defensive effects against helminth infections, allergic and autoimmune responses, and tumor suppression. This paper explores the mechanisms involved in the generation and differentiation of Th9 cells, including the cytokines responsible for their polarization and stabilization, the transcription factors necessary for their differentiation, as well as the role of Th9 cells in inflammatory and autoimmune diseases, allergic reactions, and cancer immunotherapies. Recent research has shown that the differentiation of Th9 cells is coregulated by the transcription factors transforming growth factor β (TGF-β), IL-4, and PU.1, which are also known to secrete IL-10 and IL-21. Multiple cell types, such as T and B cells, mast cells, and airway epithelial cells, are influenced by IL-9 due to its pleiotropic effects.

The NF-κB signaling system in the immunopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is an idiopathic, chronic condition characterized by episodes of inflammation in the gastrointestinal tract. The nuclear factor κB (NF-κB) system describes a family of dimeric transcription factors. Canonical NF-κB signaling is stimulated by and enhances inflammation, whereas noncanonical NF-κB signaling contributes to immune organogenesis. Dysregulation of NF-κB factors drives various inflammatory pathologies, including IBD. Signals from many immune sensors activate NF-κB subunits in the intestine, which maintain an equilibrium between local microbiota and host responses. Genetic association studies of patients with IBD and preclinical mouse models confirm the importance of the NF-κB system in host defense in the gut. Other studies have investigated the roles of these factors in intestinal barrier function and in inflammatory gut pathologies associated with IBD. NF-κB signaling modulates innate and adaptive immune responses and the production of immunoregulatory proteins, anti-inflammatory cytokines, antimicrobial peptides, and other tolerogenic factors in the intestine. Furthermore, genetic studies have revealed critical cell type-specific roles for NF-κB proteins in intestinal immune homeostasis, inflammation, and restitution that contribute to the etiopathology of IBD-associated manifestations. Here, we summarize our knowledge of the roles of these NF-κB pathways, which are activated in different intestinal cell types by specific ligands, and their cross-talk, in fueling aberrant intestinal inflammation. We argue that an in-depth understanding of aberrant immune signaling mechanisms may hold the key to identifying predictive or prognostic biomarkers and developing better therapeutics against inflammatory gut pathologies.

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.

T helper cell subsets: diversification of the field

Polarized T helper cell (Th cell) responses are important determinants of host protection. Th cell subsets tailor their functional repertoire of cytokines to their cognate antigens to efficiently contribute to their clearance. In contrast, in settings of immune abrogation, these polarized cytokine patterns of Th cells can mediate tissue damage and pathology resulting in allergy or autoimmunity. Recent technological developments in single-cell genomics and proteomics as well as advances in the high-dimensional bioinformatic analysis of complex datasets have challenged the prevailing Th cell subset classification into Th1, Th2, Th17, and other subsets. Additionally, systems immunology approaches have revealed that instructive input from the peripheral tissue microenvironment can have differential effects on the overall phenotype and molecular wiring of Th cells depending on their spatial distribution. Th cells from the blood or secondary lymphoid organs are therefore expected to follow distinct rules of regulation. In this review, the functional heterogeneity of Th cell subsets will be reviewed in the context of new technological developments and T-cell compartmentalization in tissue niches. This work will especially focus on challenges to the traditional boundaries of Th cell subsets and will discuss the underlying regulatory checkpoints, which could reveal new therapeutic strategies for various immune-mediated diseases.

Negative impact of Interleukin-9 on synovial regulatory T cells in rheumatoid arthritis

In Rheumatoid Arthritis (RA), regulatory T cells (Tregs) have been found to be enriched in the synovial fluid. Despite their accumulation, they are unable to suppress synovial inflammation. Recently, we showed the synovial enrichment of interleukin-9 (IL-9) producing helper T cells and its positive correlation with disease activity. Therefore, we investigated the impact of IL-9 on synovial Tregs in RA. Here, we confirmed high synovial Tregs in RA patients, however these cells were functionally impaired in terms of suppressive cytokine production (IL-10 and TGF-β). Abrogating IL-9/ IL-9 receptor interaction could restore the suppressive cytokine production of synovial Tregs and reduce the synovial inflammatory T cells producing IFN-γ, TNF-α, IL-17. However, blocking these inflammatory cytokines failed to show any effect on IL-9 producing T cells, highlighting IL-9's hierarchy in the inflammatory network. Thus, we propose that blocking IL-9 might dampen synovial inflammation by restoring Tregs function and inhibiting inflammatory T cells.

Anti-inflammatory and intestinal microbiota modulation properties of Ganoderma lucidum β-d-glucans with different molecular weight in an ulcerative colitis model

This study systematically investigated the therapeutic effects and the corresponding mechanisms of β-D-glucans from Ganoderma lucidum (G. lucidum) with different molecular weights (Mws) on ulcerative colitis (UC). Results showed that three β-d-glucans (GLPS, GLPN and GLPW) from G. lucidum with different Mws exhibited the significant activities on the reduction of typical symptoms of UC by regulating inflammatory cytokine levels, modulating intestinal immunity, improving intestinal microbiota and metabolism of short-chain fatty acids (SCFAs) in the dextran sulfate sodium (DSS)-induced mice model. Among them, the effects of the microwave assisted degraded fraction (GLPW) mainly containing two fractions with smaller Mw (1.33 × 104 and 3.51 × 103 g/mol) on the regulation of inflammatory factors and SCFAs metabolism were found to be comparable to those of GLPN with medium Mw (3.49 × 104 g/mol), and superior to those of GLPS with large Mw (2.42 × 106 g/mol). The effect of GLPW on regulation of intestinal microbiota was even better than that of GLPN. These findings suggested that lowering Mw by means of physical degradation could improve the anti-inflammatory activities of G. lucidum β-d-glucans. The analysis of anti-inflammatory mechanism also provided a feasible and theoretical basis for potential use of degraded β-d-glucans in the prevention and treatment of UC.

Proteostasis in T cell aging

Aging leads to a decline in immune cell function, which leaves the organism vulnerable to infections and age-related multimorbidities. One major player of the adaptive immune response are T cells, and recent studies argue for a major role of disturbed proteostasis contributing to reduced function of these cells upon aging. Proteostasis refers to the state of a healthy, balanced proteome in the cell and is influenced by synthesis (translation), maintenance and quality control of proteins, as well as degradation of damaged or unwanted proteins by the proteasome, autophagy, lysosome and cytoplasmic enzymes. This review focuses on molecular processes impacting on proteostasis in T cells, and specifically functional or quantitative changes of each of these upon aging. Importantly, we describe the biological consequences of compromised proteostasis in T cells, which range from impaired T cell activation and function to enhancement of inflamm-aging by aged T cells. Finally, approaches to improve proteostasis and thus rejuvenate aged T cells through pharmacological or physical interventions are discussed.

IL-9-Producing Th9 Cells Participate in the Occurrence and Development of Iodine-Induced Autoimmune Thyroiditis

Iodine excess may cause and aggravate autoimmune thyroiditis (AIT), which is regarded as a typical kind of autoimmune disease mainly mediated by CD4+ T cells. Thus far, it is unclear whether T helper (Th) 9 cells, a novel subpopulation of CD4+ T cells, play a potential role in AIT. Therefore, in the present study, changes in Th9 cells were detected in murine models of AIT induced by excess iodine intake to explore the possible immune mechanism. Female C57BL/6 mice were divided into 7 groups (n = 8) and were supplied with water containing 0.005% sodium iodide for 0, 2, 4, 6, 8, 10, and 12 weeks. With the extension of the high-iodine intake duration, the incidence of thyroiditis and the spleen index were significantly increased, and serum thyroglobulin antibody (TgAb) titers and interleukin 9 (IL-9, major cytokine from Th9 cells) concentrations were also increased. Additionally, it was revealed that the percentages of Th9 cells in spleen mononuclear cells (SMCs) and thyroid tissues were both markedly elevated and accompanied by increased mRNA and protein expression of IL-9 and key transcription factors of Th9 cells (PU.1 and IRF-4). Significantly, dynamic changes in Th9 cells were found, with a peak at 8 weeks after high iodine intake, the time point when thyroiditis was the most serious. Importantly, Th9 cells were detected in the areas of infiltrating lymphocytes in thyroid sections. In conclusion, the continuously increasing proportions of Th9 cells may play an important role in the occurrence and development of AIT induced by high iodine intake.

Innate mechanism of mucosal barrier erosion in the pathogenesis of acquired colitis

The colonic mucosal barrier protects against infection, inflammation, and tissue ulceration. Composed primarily of Mucin-2, proteolytic erosion of this barrier is an invariant feature of colitis; however, the molecular mechanisms are not well understood. We have applied a recurrent food poisoning model of acquired inflammatory bowel disease using Salmonella enterica Typhimurium to investigate mucosal barrier erosion. Our findings reveal an innate Toll-like receptor 4-dependent mechanism activated by previous infection that induces Neu3 neuraminidase among colonic epithelial cells concurrent with increased Cathepsin-G protease secretion by Paneth cells. These anatomically separated host responses merge with the desialylation of nascent colonic Mucin-2 by Neu3 rendering the mucosal barrier susceptible to increased proteolytic breakdown by Cathepsin-G. Depletion of Cathepsin-G or Neu3 function using pharmacological inhibitors or genetic-null alleles protected against Mucin-2 proteolysis and barrier erosion and reduced the frequency and severity of colitis, revealing approaches to preserve and potentially restore the mucosal barrier.

Research progress on the mechanism of cholesterol-25-hydroxylase in intestinal immunity

Inflammatory bowel disease (IBD), a general term encompassing Crohn's disease (CD) and ulcerative colitis (UC), and other conditions, is a chronic and relapsing autoimmune disease that can occur in any part of the digestive tract. While the cause of IBD remains unclear, it is acknowledged that the disease has much to do with the dysregulation of intestinal immunity. In the intestinal immune regulatory system, Cholesterol-25-hydroxylase (CH25H) plays an important role in regulating the function of immune cells and lipid metabolism through catalyzing the oxidation of cholesterol into 25-hydroxycholesterol (25-HC). Specifically, CH25H focuses its mechanism of regulating the inflammatory response, signal transduction and cell migration on various types of immune cells by binding to relevant receptors, and the mechanism of regulating lipid metabolism and immune cell function via the transcription factor Sterol Regulator-Binding Protein. Based on this foundation, this article will review the function of CH25H in intestinal immunity, aiming to provide evidence for supporting the discovery of early diagnostic and treatment targets for IBD.

Interplay of Chemokines Receptors, Toll-like Receptors, and Host Immunological Pathways

A comprehensive framework has been established for understanding immunological pathways, which can be categorized into eradicated and tolerable immune responses. Toll-like receptors (TLRs) are associated with specific immune responses. TH1 immunity is related to TLR7, TLR8, and TLR9, while TH2 immunity is associated with TLR1, TLR2, and TLR6. TH22 immunity is linked to TLR2, TLR4, and TLR5, and THαβ (Tr1) immunity is related to TLR3, TLR7, and TLR9. The chemokine receptor CXCR5 is a marker of follicular helper T cells, and other chemokine receptors can also be classified within a framework based on host immunological pathways. On the basis of a literature review on chemokines and immunological pathways, the following associations were identified: CCR5 with TH1 responses, CCR1 with TH1-like responses, CCR4 (basophils) and CCR3 (eosinophils) with TH2 and TH9 responses, CCR10 with TH22 responses, CCR6 with TH17 responses, CXCR3 with THαβ responses, CCR8 with regulatory T cells (Treg), and CCR2 with TH3 responses. These findings contribute to the identification of biomarkers for immune cells and provide insights into host immunological pathways. Understanding the chemokine and Toll-like receptor system is crucial for comprehending the function of the innate immune system, as well as adaptive immune responses.

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.

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.

Evaluation of the effect of ritlecitinib on the pharmacokinetics of caffeine in healthy participants

AIMS

This clinical study was conducted to evaluate the impact of ritlecitinib on the pharmacokinetics of caffeine, a cytochrome P450 1A2 (CYP1A2) substrate.

METHODS

In this single-centre, single-arm, open-label, fixed-sequence study, healthy participants received a single 100-mg dose of caffeine on 2 separate occasions: on Day 1 of Period 1 as monotherapy and on Day 8 of Period 2 after oral administration of ritlecitinib 200 mg once daily for 8 days. Serial blood samples were collected and analysed using a validated liquid chromatography-mass spectrometry assay. Pharmacokinetic parameters were estimated by using a noncompartmental method. Safety was monitored by physical examination, vital signs, electrocardiograms and laboratory assessments.

RESULTS

Twelve participants were enrolled and completed the study. Coadministration of caffeine 100 mg in the presence of steady-state levels of ritlecitinib (200 mg once daily) increased caffeine exposure compared with caffeine given alone. Area under the curve to infinity and maximum concentration of caffeine increased by approximately 165 and 10%, respectively, when coadministered with ritlecitinib. The ratios of the adjusted geometric means (90% confidence interval) for caffeine area under the curve to infinity and maximum concentration were 265.14% (234.12-300.26%) and 109.74% (103.90-15.91%), respectively, when caffeine was coadministered with steady-state ritlecitinib (test) compared with its administration alone (reference). Multiple doses of ritlecitinib when coadministered with a single dose of caffeine were generally safe and well tolerated in healthy participants.

CONCLUSION

Ritlecitinib is a moderate inhibitor of CYP1A2 and can increase systemic exposures of CYP1A2 substrates.

The World according to IL-9

Among the cytokines regulating immune cells, IL-9 has gained considerable attention for its ability to act on multiple cell types as a regulator of beneficial and pathologic immune responses. Yet, it is still not clearly defined how IL-9 impacts immune responses. IL-9 demonstrates a remarkable degree of tissue-specific functionality and has cellular sources that vary by tissue site and the context of the inflammatory milieu. Here, we provide perspective to summarize the biological activities of IL-9 and highlight cell type-specific roles in the immune pathogenesis of diseases. This perspective will be important in defining the diseases where targeting IL-9 as a therapeutic strategy would be beneficial and where it has the potential to complicate clinical outcomes.

T cells in health and disease

T cells are crucial for immune functions to maintain health and prevent disease. T cell development occurs in a stepwise process in the thymus and mainly generates CD4⁺ and CD8⁺ T cell subsets. Upon antigen stimulation, naïve T cells differentiate into CD4⁺ helper and CD8⁺ cytotoxic effector and memory cells, mediating direct killing, diverse immune regulatory function, and long-term protection. In response to acute and chronic infections and tumors, T cells adopt distinct differentiation trajectories and develop into a range of heterogeneous populations with various phenotype, differentiation potential, and functionality under precise and elaborate regulations of transcriptional and epigenetic programs. Abnormal T-cell immunity can initiate and promote the pathogenesis of autoimmune diseases. In this review, we summarize the current understanding of T cell development, CD4⁺ and CD8⁺ T cell classification, and differentiation in physiological settings. We further elaborate the heterogeneity, differentiation, functionality, and regulation network of CD4⁺ and CD8⁺ T cells in infectious disease, chronic infection and tumor, and autoimmune disease, highlighting the exhausted CD8⁺ T cell differentiation trajectory, CD4⁺ T cell helper function, T cell contributions to immunotherapy and autoimmune pathogenesis. We also discuss the development and function of γδ T cells in tissue surveillance, infection, and tumor immunity. Finally, we summarized current T-cell-based immunotherapies in both cancer and autoimmune diseases, with an emphasis on their clinical applications. A better understanding of T cell immunity provides insight into developing novel prophylactic and therapeutic strategies in human diseases.

Myeloid cell influx into the colonic epithelium is associated with disease severity and non-response to anti-Tumor Necrosis Factor Therapy in patients with Ulcerative Colitis

Ulcerative colitis (UC) is an idiopathic chronic inflammatory disease of the colon with sharply rising global prevalence. Dysfunctional epithelial compartment (EC) dynamics are implicated in UC pathogenesis although EC-specific studies are sparse. Applying orthogonal high-dimensional EC profiling to a Primary Cohort (PC; n=222), we detail major epithelial and immune cell perturbations in active UC. Prominently, reduced frequencies of mature BEST4+OTOP2+ absorptive and BEST2+WFDC2+ secretory epithelial enterocytes were associated with the replacement of homeostatic, resident TRDC+KLRD1+HOPX+ γδ+ T cells with RORA+CCL20+S100A4+ TH17 cells and the influx of inflammatory myeloid cells. The EC transcriptome (exemplified by S100A8, HIF1A, TREM1, CXCR1) correlated with clinical, endoscopic, and histological severity of UC in an independent validation cohort (n=649). Furthermore, therapeutic relevance of the observed cellular and transcriptomic changes was investigated in 3 additional published UC cohorts (n=23, 48 and 204 respectively) to reveal that non-response to anti-Tumor Necrosis Factor (anti-TNF) therapy was associated with EC related myeloid cell perturbations. Altogether, these data provide high resolution mapping of the EC to facilitate therapeutic decision-making and personalization of therapy in patients with UC.

Dynamic chromatin accessibility licenses STAT5- and STAT6-dependent innate-like function of TH9 cells to promote allergic inflammation

Allergic diseases are a major global health issue. Interleukin (IL)-9-producing helper T (TH9) cells promote allergic inflammation, yet TH9 cell effector functions are incompletely understood because their lineage instability makes them challenging to study. Here we found that resting TH9 cells produced IL-9 independently of T cell receptor (TCR) restimulation, due to STAT5- and STAT6-dependent bystander activation. This mechanism was seen in circulating cells from allergic patients and was restricted to recently activated cells. STAT5-dependent Il9/IL9 regulatory elements underwent remodeling over time, inactivating the locus. A broader 'allergic TH9' transcriptomic and epigenomic program was also unstable. In vivo, TH9 cells induced airway inflammation via TCR-independent, STAT-dependent mechanisms. In allergic patients, TH9 cell expansion was associated with responsiveness to JAK inhibitors. These findings suggest that TH9 cell instability is a negative checkpoint on bystander activation that breaks down in allergy and that JAK inhibitors should be considered for allergic patients with TH9 cell expansion.

Deficiency of the CD155-CD96 immune checkpoint controls IL-9 production in giant cell arteritis

Loss of function of inhibitory immune checkpoints, unleashing pathogenic immune responses, is a potential risk factor for autoimmune disease. Here, we report that patients with the autoimmune vasculitis giant cell arteritis (GCA) have a defective CD155-CD96 immune checkpoint. Macrophages from patients with GCA retain the checkpoint ligand CD155 in the endoplasmic reticulum (ER) and fail to bring it to the cell surface. CD155^low antigen-presenting cells induce expansion of CD4⁺CD96⁺ T cells, which become tissue invasive, accumulate in the blood vessel wall, and release the effector cytokine interleukin-9 (IL-9). In a humanized mouse model of GCA, recombinant human IL-9 causes vessel wall destruction, whereas anti-IL-9 antibodies efficiently suppress innate and adaptive immunity in the vasculitic lesions. Thus, defective surface translocation of CD155 creates antigen-presenting cells that deviate T cell differentiation toward Th9 lineage commitment and results in the expansion of vasculitogenic effector T 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.

ERG Functionally Overlaps with Other Ets Proteins in Promoting TH9 Cell Expression of Il9 during Allergic Lung Inflammation

CD4+ TH cells develop into subsets that are specialized in the secretion of particular cytokines to mediate restricted types of inflammation and immune responses. Among the subsets that promote development of allergic inflammatory responses, IL-9-producing TH9 cells are regulated by a number of transcription factors. We have previously shown that the E26 transformation-specific (Ets) family members PU.1 and Ets translocation variant 5 (ETV5) function in parallel to regulate IL-9. In this study we identified a third member of the Ets family of transcription factors, Ets-related gene (ERG), that mediates IL-9 production in TH9 cells in the absence of PU.1 and ETV5. Chromatin immunoprecipitation assays revealed that ERG interaction at the Il9 promoter region is restricted to the TH9 lineage and is sustained during murine TH9 polarization. Knockdown or knockout of ERG during murine or human TH9 polarization in vitro led to a decrease in IL-9 production in TH9 cells. Deletion of ERG in vivo had modest effects on IL-9 production in vitro or in vivo. However, in the absence of PU.1 and ETV5, ERG was required for residual IL-9 production in vitro and for IL-9 production by lung-derived CD4 T cells in a mouse model of chronic allergic airway disease. Thus, ERG contributes to IL-9 regulation in TH9 cells.

3D genome alterations in T cells associated with disease activity of systemic lupus erythematosus

OBJECTIVES

Three-dimensional (3D) genome alterations can dysregulate gene expression by rewiring physical interactions within chromosomes in a tissue-specific or cell-specific manner and lead to diseases. We aimed to elucidate the 3D genome structure and its role in gene expression networks dysregulated in systemic lupus erythematosus (SLE).

METHODS

We performed Hi-C experiments using CD4+ T cells from 7 patients with SLE and 5 age-matched and sex-matched healthy controls (HCs) combined with RNA sequencing analysis. Further integrative analyses, including transcription factor motif enrichment, SPI1 knockdown and histone modifications (H3K27ac, H3K4me1, H3K4me3), were performed for altered loop-associated gene loci in SLE.

RESULTS

We deciphered the 3D chromosome organisation in T cells of patients with SLE and found it was clearly distinct from that of HCs and closely associated with the disease activity of SLE. Importantly, we identified loops within chromosomes associated with the disease activity of SLE and differentially expressed genes and found some key histone modifications close to these loops. Moreover, we demonstrated the contribution of the transcription factor SPI1, whose motif is located in the altered loop in SLE, to the overexpression of interferon pathway gene. In addition, we identified the potential influences of genetic variations in 3D genome alterations in SLE.

CONCLUSIONS

Our results highlight the 3D genome structure alterations associated with SLE development and provide a foundation for future interrogation of the relationships between chromosome structure and gene expression control in SLE.

CD4 T-Cell Subsets and the Pathophysiology of Inflammatory Bowel Disease

Inflammatory bowel disease (IBD) is an umbrella term for the chronic immune-mediated idiopathic inflammation of the gastrointestinal tract, manifesting as Crohn's disease (CD) or ulcerative colitis (UC). IBD is characterized by exacerbated innate and adaptive immunity in the gut in association with microbiota dysbiosis and the disruption of the intestinal barrier, resulting in increased bacterial exposure. In response to signals from microorganisms and damaged tissue, innate immune cells produce inflammatory cytokines and factors that stimulate T and B cells of the adaptive immune system, and a prominent characteristic of IBD patients is the accumulation of inflammatory T-cells and their proinflammatory-associated cytokines in intestinal tissue. Upon antigen recognition and activation, CD4 T-cells differentiate towards a range of distinct phenotypes: T helper(h)1, Th2, Th9, Th17, Th22, T follicular helper (Tfh), and several types of T-regulatory cells (Treg). T-cells are generated according to and adapt to microenvironmental conditions and participate in a complex network of interactions among other immune cells that modulate the further progression of IBD. This review examines the role of the CD4 T-cells most relevant to IBD, highlighting how these cells adapt to the environment and interact with other cell populations to promote or inhibit the development of IBD.

A Protective Role of NOD2 on Oxazolone-induced Intestinal Inflammation Through IL-1β-mediated Signalling Pathway

BACKGROUND AND AIMS

NOD2 has emerged as a critical player in the induction of both Th1 and Th2 responses for potentiation and polarisation of antigen-dependent immunity. Loss-of-function mutations in the NOD2-encoding gene and deregulation of its downstream signalling pathway have been linked to Crohn's disease. Although it is well documented that NOD2 is capable of sensing bacterial muramyl dipeptide, it remains counter-intuitive to link development of overt intestinal inflammation to a loss of bacterial-induced inflammatory response. We hypothesised that a T helper bias could also contribute to an autoimmune-like colitis different from inflammation that is fully fledged by Th1 type cells.

METHODS

An oedematous bowel wall with a mixed Th1/Th2 response was induced in mice by intrarectal instillation of the haptenating agent oxazolone. Survival and clinical scoring were evaluated. At several time points after instillation, colonic damage was assessed by macroscopic and microscopic observations. To evaluate the involvement of NOD2 in immunochemical phenomena, quantitative polymerase chain reaction [PCR] and flow cytometry analysis were performed. Bone marrow chimera experimentation allowed us to evaluate the role of haematopoietic/non-hematopoietic NOD2-expressing cells.

RESULTS

Herein, we identified a key regulatory circuit whereby NOD2-mediated sensing of a muramyl dipeptide [MDP] by radio-resistant cells improves colitis with a mixed Th1/Th2 response that is induced by oxazolone. Genetic ablation of either Nod2 or Ripk2 precipitated oxazolone colitis that is predominantly linked to a lack of interferon-gamma. Bone marrow chimera experiments revealed that inactivation of Nod2 signalling in non-haematopoietic cells is causing a biased M1-M2 polarisation of macrophages and a decreased frequency of splenic regulatory T cells that correlates with an impaired activation of CD4 + T cells within mesenteric lymph nodes. Mechanistically, mice were protected from oxazolone-induced colitis upon administration of MDP in an interleukin-1- and interleukin-23-dependent manner.

CONCLUSIONS

These findings indicate that Nod2 signalling may prevent pathological conversion of T helper cells for maintenance of tissue homeostasis.

Unveiling the biological role of sphingosine-1-phosphate receptor modulators in inflammatory bowel diseases

Inflammatory bowel disease (IBD) is chronic inflammation of the gastrointestinal tract that has a high epidemiological prevalence worldwide. The increasing disease burden worldwide, lack of response to current biologic therapeutics, and treatment-related immunogenicity have led to major concerns regarding the clinical management of IBD patients and treatment efficacy. Understanding disease pathogenesis and disease-related molecular mechanisms is the most important goal in developing new and effective therapeutics. Sphingosine-1-phosphate (S1P) receptor (S1PR) modulators form a class of oral small molecule drugs currently in clinical development for IBD have shown promising effects on disease improvement. S1P is a sphingosine-derived phospholipid that acts by binding to its receptor S1PR and is involved in the regulation of several biological processes including cell survival, differentiation, migration, proliferation, immune response, and lymphocyte trafficking. T lymphocytes play an important role in regulating inflammatory responses. In inflamed IBD tissue, an imbalance between T helper (Th) and regulatory T lymphocytes and Th cytokine levels was found. The S1P/S1PR signaling axis and metabolism have been linked to inflammatory responses in IBD. S1P modulators targeting S1PRs and S1P metabolism have been developed and shown to regulate inflammatory responses by affecting lymphocyte trafficking, lymphocyte number, lymphocyte activity, cytokine production, and contributing to gut barrier function.

Molecular Mechanisms Underlying IL-33-Mediated Inflammation in Inflammatory Bowel Disease

Interleukin-33 (IL-33) is a cytokine defined by its pleiotropic function, acting either as a typical extracellular cytokine or as a nuclear transcription factor. IL-33 and its receptor, suppression of tumorigenicity 2 (ST2), interact with both innate and adaptive immunity and are considered critical regulators of inflammatory disorders. The IL-33/ST2 axis is involved in the maintenance of intestinal homeostasis; on the basis of their role as pro- or anti-inflammatory mediators of first-line innate immunity, their expression is of great importance in regard to mucosal defenses. Mucosal immunity commonly presents an imbalance in inflammatory bowel disease (IBD). This review summarizes the main cellular and molecular aspects of IL-33 and ST2, mainly focusing on the current evidence of the pro- and anti-inflammatory effects of the IL-33/ST2 axis in the course of ulcerative colitis and Crohn's disease, as well as the molecular mechanisms underlying the association of IL-33/ST2 signaling in IBD pathogenesis. Although IL-33 modulates and impacts the development, course, and recurrence of the inflammatory response, the exact role of this molecule is elusive, and it seems to be associated with the subtype of the disease or the disease stage. Unraveling of IL-33/ST2-mediated mechanisms involved in IBD pathology shows great potential for clinical application as therapeutic targets in IBD treatment.

The Cytokine Network in Colorectal Cancer: Implications for New Treatment Strategies

Colorectal cancer (CRC) is one of the most frequent tumor entities worldwide with only limited therapeutic options. CRC is not only a genetic disease with several mutations in specific oncogenes and/or tumor suppressor genes such as APC, KRAS, PIC3CA, BRAF, SMAD4 or TP53 but also a multifactorial disease including environmental factors. Cancer cells communicate with their environment mostly via soluble factors such as cytokines, chemokines or growth factors to generate a favorable tumor microenvironment (TME). The TME, a heterogeneous population of differentiated and progenitor cells, plays a critical role in regulating tumor development, growth, invasion, metastasis and therapy resistance. In this context, cytokines from cancer cells and cells of the TME influence each other, eliciting an inflammatory milieu that can either enhance or suppress tumor growth and metastasis. Additionally, several lines of evidence exist that the composition of the microbiota regulates inflammatory processes, controlled by cytokine secretion, that play a role in carcinogenesis and tumor progression. In this review, we discuss the cytokine networks between cancer cells and the TME and microbiome in colorectal cancer and the related treatment strategies, with the goal to discuss cytokine-mediated strategies that could overcome the common therapeutic resistance of CRC tumors.

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.

Deciphering the role of autophagy in the immunopathogenesis of inflammatory bowel disease

Inflammatory bowel disease (IBD) is a typical immune-mediated chronic inflammatory disorder. Following the industrialization and changes in lifestyle, the incidence of IBD in the world is rising, which makes health concerns and heavy burdens all over the world. However, the pathogenesis of IBD remains unclear, and the current understanding of the pathogenesis involves dysregulation of mucosal immunity, gut microbiome dysbiosis, and gut barrier defect based on genetic susceptibility and environmental triggers. In recent years, autophagy has emerged as a key mechanism in IBD development and progression because Genome-Wide Association Study revealed the complex interactions of autophagy in IBD, especially immunopathogenesis. Besides, autophagy markers are also suggested to be potential biomarkers and target treatment in IBD. This review summarizes the autophagy-related genes regulating immune response in IBD. Furthermore, we explore the evolving evidence that autophagy interacts with intestinal epithelial and immune cells to contribute to the inflammatory changes in IBD. Finally, we discuss how novel discovery could further advance our understanding of the role of autophagy and inform novel therapeutic strategies in IBD.

Cancer as a Dysfunctional Immune Disorder: Pro-Tumor TH1-like Immune Response and Anti-Tumor THαβ Immune Response Based on the Complete Updated Framework of Host Immunological Pathways

Host immunological pathways are delicate to cope with different types of pathogens. In this article, we divide immunological pathways into two groups: Immunoglobulin G-related eradicable immunities and Immunoglobulin A-related tolerable immunities. Once immune cells encounter an antigen, they can become anergic or trigger immune reactions. Immunoglobulin D B cells and γδ T cells are recognizing self-antigens to become anergic. Immunoglobulin M B cells and αβ T cells can trigger host immune reactions. Eradicable immune responses can be divided into four groups: TH1/TH2/TH22/THαβ (TH—T Helper cell groups). Tolerable immune responses can be divided into four groups: TH1-like/TH9/TH17/TH3. Four groups mean hosts can cope with four types of pathogens. Cancer is related to immune dysfunction. TH1-like immunity is pro-tumor immunity and THαβ is anti-tumor immunity. TH1-like immunity is the host tolerable immunity against intracellular micro-organisms. THαβ immunity is the host eradicable immunity against viruses. Cancer is also related to clonal anergy by Immunoglobulin D B cells and γδ T cells. Oncolytic viruses are related to the activation of anti-viral THαβ immunity. M2 macrophages are related to the tolerable TH1-like immunity, and they are related to metastasis. This review is key to understanding the immune pathogenesis of cancer. We can then develop better therapeutic agents to treat cancer.

The role of a key transcription factor PU.1 in autoimmune diseases

PU.1, a transcription factor member of the E26 transformation-specific family, affects the function of a variety of immune cells in several physiological and pathological conditions. Previous studies studying the role of PU.1 in pathological conditions have mainly focused on immune system-related cancers, and a series of articles have confirmed that PU.1 mutation can induce a variety of immune cell-related malignancies. The underlying mechanism has also been extensively validated. However, the role of PU.1 in other major immune system-related diseases, namely, systemic autoimmune diseases, is still unclear. It was only in recent years that researchers began to gradually realize that PU.1 also played an important role in a variety of autoimmune diseases, such as rheumatoid arthritis (RA), experimental autoimmune encephalomyelitis (EAE) and systemic lupus erythematosus (SLE). This review article summarizes the findings of recent studies that investigated the role of PU.1 in various autoimmune diseases and the related underlying mechanisms. Furthermore, it presents new ideas and provides insight into the role of PU.1 as a potential treatment target for autoimmune diseases and highlights existing research problems and future research directions in related fields.

Cytokine responsive networks in human colonic epithelial organoids unveil a molecular classification of inflammatory bowel disease

Interactions between the epithelium and the immune system are critical in the pathogenesis of inflammatory bowel disease (IBD). In this study, we mapped the transcriptional landscape of human colonic epithelial organoids in response to different cytokines responsible for mediating canonical mucosal immune responses. By profiling the transcriptome of human colonic organoids treated with the canonical cytokines interferon gamma, interleukin-13, -17A, and tumor necrosis factor alpha with next-generation sequencing, we unveil shared and distinct regulation patterns of epithelial function by different cytokines. An integrative analysis of cytokine responses in diseased tissue from patients with IBD (n = 1,009) reveals a molecular classification of mucosal inflammation defined by gradients of cytokine-responsive transcriptional signatures. Our systems biology approach detected signaling bottlenecks in cytokine-responsive networks and highlighted their translational potential as theragnostic targets in intestinal inflammation.

Characterisation of the Circulating Transcriptomic Landscape in Inflammatory Bowel Disease Provides Evidence for Dysregulation of Multiple Transcription Factors Including NFE2, SPI1, CEBPB, and IRF2

AIM

To assess the pathobiological and translational importance of whole-blood transcriptomic analysis in inflammatory bowel disease [IBD].

METHODS

We analysed whole-blood expression profiles from paired-end sequencing in a discovery cohort of 590 Europeans recruited across six countries in the IBD Character initiative (newly diagnosed patients with Crohn's disease [CD; n = 156], ulcerative colitis [UC; n = 167], and controls [n = 267]), exploring differential expression [DESeq2], co-expression networks [WGCNA], and transcription factor involvement [EPEE, ChEA, DoRothEA]. Findings were validated by analysis of an independent replication cohort [99 CD, 100 UC, 95 controls]. In the discovery cohort, we also defined baseline expression correlates of future treatment escalation using cross-validated elastic-net and random forest modelling, along with a pragmatic ratio detection procedure.

RESULTS

Disease-specific transcriptomes were defined in IBD [8697 transcripts], CD [7152], and UC [8521], with the most highly significant changes in single genes, including CD177 (log2-fold change [LFC] = 4.63, p = 4.05 × 10-118), MCEMP1 [LFC = 2.45, p = 7.37 × 10-109], and S100A12 [LFC = 2.31, p = 2.15 × 10-93]. Significantly over-represented pathways included IL-1 [p = 1.58 × 10-11], IL-4, and IL-13 [p = 8.96 × 10-9]. Highly concordant results were obtained using multiple regulatory activity inference tools applied to the discovery and replication cohorts. These analyses demonstrated central roles in IBD for the transcription factors NFE2, SPI1 [PU.1], CEBPB, and IRF2, all regulators of cytokine signalling, based on a consistent signal across cohorts and transcription factor ranking methods. A number of simple transcriptome-based models were associated with the need for treatment escalation, including the binary CLEC5A/CDH2 expression ratio in UC (hazard ratio = 23.4, 95% confidence interval [CI] 5.3-102.0).

CONCLUSIONS

Transcriptomic analysis has allowed for a detailed characterisation of IBD pathobiology, with important potential translational implications.

The Mechanisms of Effector Th Cell Responses Contribute to Treg Cell Function: New Insights into Pathogenesis and Therapy of Asthma

CD4 ⁺ helper T (Th) cell subsets are critically involved in the pathogenesis of asthma. Naive Th cells differentiate into different subsets under the stimulation of different sets of cytokines, and the differentiation process is dominantly driven by lineage specific transcription factors, such as T-bet (Th1), GATA3 (Th2), RORγt (Th17) and Foxp3 (Treg). The differentiation mechanisms driven by these transcription factors are mutually exclusive, resulting in functional inhibition of these Th subsets to each other, particularly prominent between effector Th cells and Treg cells, such as Th2 versus Treg cells and Th17 versus Treg cells. Being of significance in maintaining immune homeostasis, the balance between effector Th cell response and Treg cell immunosuppression provides an immunological theoretical basis for us to understand the immunopathological mechanism and develop the therapy strategies of asthma. However, recent studies have found that certain factors involved in effector Th cells response, such as cytokines and master transcription factors (IL-12 and T-bet of Th1, IL-4 and GATA3 of Th2, IL-6 and RORγt of Th17), not only contribute to immune response of effector Th cells, but also promote the development and function of Treg cells, therefore bridging the interplay between effector Th cell immune responses and Treg cell immunosuppression. Although we have an abundant knowledge concerning the role of these cytokines and transcription factors in effector Th cell responses, our understanding on their role in Treg cell development and function is scattered thus need to be summarized. This review summarized the role of these cytokines and transcription factors involved in effector Th cell responses in the development and function of Treg cells, in the hope of providing new insights of understanding the immunopathological mechanism and seeking potential therapy strategies of asthma.

Molecules involved in the development of Barrett's esophagus phenotype in chronic eosinophilic esophagitis

This paper aims to investigate the molecules involved in development of Barrett's esophagus (BE) in human eosinophilic esophagitis (EoE). Histopathological, immunohistochemical, real-time PCR Immuno blot, and ELISA analyses are performed to identify the signature genes and proteins involved in the progression of BE in EoE. We detected characteristic features of BE like intermediate columnar-type epithelial cells, induced BE signature genes like ErbB3, CDX1, ErbB2IP in the esophageal mucosa of patients with EoE. In addition, we had observed several BE-associated proteins such as TFF3, p53 and the progression markers like EGFR, p16, MICA, MICB, and MHC molecules in esophageal biopsies of patients with chronic EoE. Interestingly, we also detected mucin-producing columnar cells and MUC-2, MUC-4, and MUC5AC genes and proteins along with induced IL-9 in patients with chronic EoE. A strong correlation of IL-9 with mucin genes is observed that implicated a possible role for IL-9 in the transformation of esophageal squamous epithelial cells to columnar epithelial cells in patients with EoE. These findings indicate that IL-9 may have an important role in BE development in patients with chronic EoE. We also discovered that IL-9 stimulates mucin-producing and barrier cell transcripts and proteins such CK8/18, GATA4, SOX9, TFF1, MUC5AC, and tight junction proteins in primary esophageal epithelial cells when exposed to IL-9. Taken together, these findings provide evidence that indeed IL-9 has a role in the initiation and progression of BE characteristics like development of mucin-producing columnar epithelial cells in patients with chronic EoE.NEW & NOTEWORTHY Intermediate columnar-type epithelial cells are observed in biopsies of patients with EoE. Induced BE signature genes (CK8/18, CDX1 GATA4, SOX9, and Occludin) were observed in patients with chronic EoE. Induction of IL-9 and its correlation with eosinophils mucin-producing genes and proteins was observed in patients with EoE. Induced IL-9 may be responsible for the development of BE in patients with chronic EoE.

TIGIT Deficiency Protects Mice From DSS-Induced Colitis by Regulating IL-17A–Producing CD4+ Tissue-Resident Memory T Cells

Tissue-resident memory T cells (T_RM cells) have been shown to play an instrumental role in providing local immune responses for pathogen clearance in barrier tissues. However, their contribution to inflammatory bowel diseases (IBDs) and the underlying regulation are less clear. Here, we identified a critical role of T-cell immunoreceptor with immunoglobulin and ITIM (TIGIT) in regulating CD4⁺ T_RM cells in an experimental model of intestinal inflammation. We found that CD4+ TRM cells were increased and correlated with disease activities in mice with dextran sulfate sodium (DSS)-induced colitis. Phenotypically, these CD4⁺ T_RM cells could be classified into CD69⁺CD103⁻ and CD69⁺CD103⁺ subsets. Functionally, these CD4⁺ T_RM cells were heterogeneous. CD69⁺CD103⁻ CD4⁺ T_RM cells were pro-inflammatory and produced interferon-γ (IFNγ) and interleukin-17A (IL-17A), which accounted for 68.7% and 62.9% of total IFNγ⁺ and IL-17A⁺ CD4⁺ T cells, respectively, whereas CD69⁺CD103⁺ CD4⁺ T_RM cells accounted for 73.7% Foxp3⁺ regulatory T cells. TIGIT expression was increased in CD4⁺ T cells in the gut of mice with DSS-induced colitis. TIGIT deficiency impaired IL-17A expression in CD69⁺CD103⁻ CD4⁺ T_RM cells specifically, resulting in ameliorated gut inflammation and tissue injury. Together, this study provides new insights into the regulation of gut inflammation that TIGIT deficiency protects mice from DSS-induced colitis, which might have a potential therapeutic value in the treatment of IBDs.

The Interactions Between Autoinflammation and Type 2 Immunity: From Mechanistic Studies to Epidemiologic Associations

Autoinflammatory diseases are a group of clinical syndromes characterized by constitutive overactivation of innate immune pathways. This results in increased production of or responses to monocyte- and neutrophil-derived cytokines such as interleukin-1β (IL-1β), Tumor Necrosis Factor-α (TNF-α), and Type 1 interferon (IFN). By contrast, clinical allergy is caused by dysregulated type 2 immunity, which is characterized by expansion of T helper 2 (Th2) cells and eosinophils, as well as overproduction of the associated cytokines IL-4, IL-5, IL-9, and IL-13. Traditionally, type 2 immune cells and autoinflammatory effectors were thought to counter-regulate each other. However, an expanding body of evidence suggests that, in some contexts, autoinflammatory pathways and cytokines may potentiate type 2 immune responses. Conversely, type 2 immune cells and cytokines can regulate autoinflammatory responses in complex and context-dependent manners. Here, we introduce the concepts of autoinflammation and type 2 immunity. We proceed to review the mechanisms by which autoinflammatory and type 2 immune responses can modulate each other. Finally, we discuss the epidemiology of type 2 immunity and clinical allergy in several monogenic and complex autoinflammatory diseases. In the future, these interactions between type 2 immunity and autoinflammation may help to expand the spectrum of autoinflammation and to guide the management of patients with various autoinflammatory and allergic diseases.