MLL4 prepares the enhancer landscape for Foxp3 induction via chromatin looping.

MLL4 is an essential subunit of the histone H3 Lys4 (H3K4)-methylation complexes. We found that MLL4 deficiency compromised the development of regulatory T cells (Treg cells) and resulted in a substantial decrease in monomethylated H3K4 (H3K4me1) and chromatin interaction at putative gene enhancers, a considerable portion of which were not direct targets of MLL4 but were enhancers that interacted with MLL4-bound sites. The decrease in H3K4me1 and chromatin interaction at the enhancers not bound by MLL4 correlated with MLL4 binding at distant interacting regions. Deletion of an upstream MLL4-binding site diminished the abundance of H3K4me1 at the regulatory elements of the gene encoding the transcription factor Foxp3 that were looped to the MLL4-binding site and compromised both the thymic differentiation and the inducible differentiation of Treg cells. We found that MLL4 catalyzed methylation of H3K4 at distant unbound enhancers via chromatin looping, which identifies a previously unknown mechanism for regulating the T cell enhancer landscape and affecting Treg cell differentiation.

The Cytokine TGF-ß Induces Interleukin-31 Expression from Dermal Dendritic Cells to Activate Sensory Neurons and Stimulate Wound Itching.

Cutaneous wound healing is associated with the unpleasant sensation of itching. Here we investigated the mechanisms underlying this type of itch, focusing on the contribution of soluble factors released during healing. We found high amounts of interleukin 31 (IL-31) in skin wound tissue during the peak of itch responses. Il31-/- mice lacked wound-induced itch responses. IL-31 was released by dermal conventional type 2 dendritic cells (cDC2s) recruited to wounds and increased itch sensory neuron sensitivity. Transfer of cDC2s isolated from late-stage wounds into healthy skin was sufficient to induce itching in a manner dependent on IL-31 expression. Addition of the cytokine TGF-ß1, which promotes wound healing, to dermal DCs in vitro was sufficient to induce Il31 expression, and Tgfbr1f/f CD11c-Cre mice exhibited reduced scratching and decreased Il31 expression in wounds in vivo. Thus, cDC2s promote itching during skin would healing via a TGF-ß-IL-31 axis with implications for treatment of wound itching.

High Glucose Intake Exacerbates Autoimmunity through Reactive-Oxygen-Species-Mediated TGF-ß Cytokine Activation.

Diet has been suggested to be a potential environmental risk factor for the increasing incidence of autoimmune diseases, yet the underlying mechanisms remain elusive. Here, we show that high glucose intake exacerbated autoimmunity in mouse models of colitis and experimental autoimmune encephalomyelitis (EAE). We elucidated that high amounts of glucose specifically promoted T helper-17 (Th17) cell differentiation by activating transforming growth factor-ß (TGF-ß) from its latent form through upregulation of reactive oxygen species (ROS) in T cells. We further determined that mitochondrial ROS (mtROS) are key for high glucose-induced TGF-ß activation and Th17 cell generation. We have thus revealed a previously unrecognized mechanism underlying the adverse effects of high glucose intake in the pathogenesis of autoimmunity and inflammation.

The DNA-binding inhibitor Id3 regulates IL-9 production in CD4(+) T cells.

The molecular mechanisms by which signaling via transforming growth factor-ß (TGF-ß) and interleukin 4 (IL-4) control the differentiation of CD4(+) IL-9-producing helper T cells (TH9 cells) remain incompletely understood. We found here that the DNA-binding inhibitor Id3 regulated TH9 differentiation, as deletion of Id3 increased IL-9 production from CD4(+) T cells. Mechanistically, TGF-ß1 and IL-4 downregulated Id3 expression, and this process required the kinase TAK1. A reduction in Id3 expression enhanced binding of the transcription factors E2A and GATA-3 to the Il9 promoter region, which promoted Il9 transcription. Notably, Id3-mediated control of TH9 differentiation regulated anti-tumor immunity in an experimental melanoma-bearing model in vivo and also in human CD4(+) T cells in vitro. Thus, our study reveals a previously unrecognized TAK1-Id3-E2A-GATA-3 pathway that regulates TH9 differentiation.

T Cell Receptor-Regulated TGF-ß Type I Receptor Expression Determines T Cell Quiescence and Activation.

It is unclear how quiescence is enforced in naive T cells, but activation by foreign antigens and self-antigens is allowed, despite the presence of inhibitory signals. We showed that active transforming growth factor ß (TGF-ß) signaling was present in naive T cells, and T cell receptor (TCR) engagement reduced TGF-ß signaling during T cell activation by downregulating TGF-ß type 1 receptor (TßRI) through activation of caspase recruitment domain-containing protein 11 (CARD11) and nuclear factor κB (NF-κB). TGF-ß prevented TCR-mediated TßRI downregulation, but this was abrogated by interleukin-6 (IL-6). Mitigation of TCR-mediated TßRI downregulation through overexpression of TßRI in naive and activated T cells rendered T cells less responsive and suppressed autoimmunity. Naive T cells in autoimmune patients exhibited reduced TßRI expression and increased TCR-driven proliferation compared to healthy subjects. Thus, TCR-mediated regulation of TßRI-TGF-ß signaling acts as a crucial criterion to determine T cell quiescence and activation.

Transforming Growth Factor-ß Signaling in Regulatory T Cells Controls T Helper-17 Cells and Tissue-Specific Immune Responses.

Regulatory T cells (Treg cells) perform suppressive functions in disparate tissue environments and against many inflammatory insults, yet the tissue-enriched factor(s) that influence Treg cell phenotype and function remain largely unknown. We have shown a vital role for transforming growth factor-ß (TGF-ß) signals in safe-guarding specific Treg cell functions. TGF-ß signals were dispensable for steady-state Treg cell homeostasis and for Treg cell suppression of T cell proliferation and T helper-1 (Th1) cell differentiation. However, Treg cells require TGF-ß signals to appropriately dampen Th17 cells and regulate responses in the gastrointestinal tract. TGF-ß signaling maintains CD103 expression, promotes expression of the colon-specific trafficking molecule GPR15, and inhibits expression of GPR174, a receptor for lysophosphatidylserine, on Treg cells, collectively supporting the accumulation and retention of Treg cells in the colon and control of colitogenic responses. Thus, we reveal an unrecognized function for TGF-ß signaling as an upstream factor controlling Treg cell activity in specific tissue environments.

[Research Progress in High-Sugar Diet and Inflammatory Diseases].

High-sugar diet causes various diseases, including insulin resistance, diabetes, and non-alcoholic fatty liver disease (NAFLD). In recent years, as researchers probe deeper and deeper into issues concerning high-sugar diet, the impact of high-sugar diet on inflammatory diseases such as autoimmune diseases and infectious diseases has been gradually uncovered and clarified. In this review, we summarized the current research progress on high-sugar diet and inflammatory diseases, and suggested that a high-sugar diet based on high intake of glucose and fructose may be an important factor inducing the exacerbation of chronic inflammatory diseases such as autoimmune diseases. Moreover, we also summarized the regulatory mechanisms through which high-sugar diet induces exacerbation of inflammatory diseases. In addition, we stated that conducting extensive clinical research and research in real-life settings and pursuing thorough investigation to reveal the different involvement of high-glucose diet and high-fructose diet in immune regulation are the key scientific issues that need urgent solutions in the future.

Irinotecan (CPT-11)-induced elevation of bile acids potentiates suppression of IL-10 expression.

Irinotecan (CPT-11) is a first-line anti-colon cancer drug, however; CPT-11-induced toxicity remains a key factor limiting its clinical application. To search for clues to the mechanism of CPT-11-induced toxicity, metabolomics was applied using ultra-performance liquid chromatography coupled with electrospray ionization quadrupole time-of-flight mass spectrometry. Intraperitoneal injection of 50 mg/kg of CPT-11 induced loss of body weight, and intestine toxicity. Changes in gallbladder morphology suggested alterations in bile acid metabolism, as revealed at the molecular level by analysis of the liver, bile, and ileum metabolomes between the vehicle-treated control group and the CPT-11-treated group. Analysis of immune cell populations further showed that CPT-11 treatment significantly decreased the IL-10-producing CD4 T cell frequency in intestinal lamina propria lymphocytes, but not in spleen or mesenteric lymph nodes. In vitro cell culture studies showed that the addition of bile acids deoxycholic acid and taurodeoxycholic acid accelerated the CPT-11-induced suppression of IL-10 secretion by activated CD4(+) naive T cells isolated from mouse splenocytes. These results showed that CPT-11 treatment caused metabolic changes in the composition of bile acids that altered CPT-11-induced suppression of IL-10 expression.

Regulatory T cells in oral squamous cell carcinoma.

Regulatory T cells (Tregs) play a critical role in modulating and maintaining immune homeostasis and tolerance. They accumulate in many types of tumors and play a critical role in tumor evasion of immune surveillance. Oral cancer is characterized by an increase in the number of infiltrating Tregs; however, the significance of this increase on the prognosis of oral cancer is controversial. This review focuses on the function of Tregs in oral squamous cell carcinoma and its implications on prognosis. We also discuss potential therapeutic strategies aimed at Tregs modification in oral SCC.

Role of distinct CD4(+) T helper subset in pathogenesis of oral lichen planus.

Oral lichen planus (OLP) is one of the most common chronic inflammatory oral mucosal diseases with T-cell-mediated immune pathogenesis. In subepithelial and lamina propria of OLP local lesions, the presence of CD4(+) T helper (CD4(+) Th) cells appeared as the major lymphocytes. These CD4(+) T lymphocytes can differentiate into distinct Th cell types such as Th1, Th2, Treg, Th17, Th22, Th9, and Tfh within the context of certain cytokines environment. Growing evidence indicated that Th1/Th2 imbalance may greatly participate into the cytokine network of OLP immunopathology. In addition, Th1/Th2 imbalance can be regulated by the Treg subset and also greatly influenced by the emerging novel CD4(+) Th subset Th17. Furthermore, the presence of novel subsets Th22, Th9 and Tfh in OLP patients is yet to be clarified. All these Th subsets and their specific cytokines may play a critical role in determining the character, extent and duration of immune responses in OLP pathogenesis. Therefore, we review the roles of distinct CD4(+) Th subsets and their signature cytokines in determining disease severity and susceptibility of OLP and also reveal the novel therapeutic strategies based on T lymphocytes subsets in OLP treatment.

TSG-6 Inhibits the NF-κB Signaling Pathway and Promotes the Odontogenic Differentiation of Dental Pulp Stem Cells via CD44 in an Inflammatory Environment.

In pulpitis, dentinal restorative processes are considerably associated with undifferentiated mesenchymal cells in the pulp. This study aimed to investigate strategies to improve the odonto/osteogenic differentiation of dental pulp stem cells (DPSCs) in an inflammatory environment. After pretreatment of DPSCs with 20 ng/mL tumor necrosis factor-induced protein-6 (TSG-6), DPSCs were cultured in an inflammation-inducing solution. Real-time polymerase chain reaction and Western blotting were performed to measure the expression levels of nuclear factor kappa B (NF-κB) and odonto/osteogenic differentiation markers, respectively. Cell Counting Kit-8 and 5-ethynyl-2'-deoxyuridine assays were used to assess cell proliferation and activity. Subcutaneous ectopic osteogenesis and mandibular bone cultures were performed to assess the effects of TSG-6 in vivo. The expression levels of odonto/osteogenic markers were higher in TSG-6-pre-treated DPSCs than nontreated DPSCs, whereas NF-κB-related proteins were lower after the induction of inflammation. An anti-CD44 antibody counteracted the rescue effect of TSG-6 on DPSC activity and mineralization in an inflammatory environment. Exogenous administration of TSG-6 enhanced the anti-inflammatory properties of DPSCs and partially restored their mineralization function by inhibiting NF-κB signaling. The mechanism of action of TSG-6 was attributed to its interaction with CD44. These findings reveal novel mechanisms by which DPSCs counter inflammation and provide a basis for the treatment of pulpitis.

CPT-11 mitigates autoimmune diseases by suppressing effector T cells without affecting long-term anti-tumor immunity.

The incidence of autoimmune diseases has significantly increased over the past 20 years. Excessive host immunoreactions and disordered immunoregulation are at the core of the pathogenesis of autoimmune diseases. The traditional anti-tumor chemotherapy drug CPT-11 is associated with leukopenia. Considering that CPT-11 induces leukopenia, we believe that it is a promising drug for the control of autoimmune diseases. Here, we show that CPT-11 suppresses T cell proliferation and pro-inflammatory cytokine production in healthy C57BL/6 mice and in complete Freund's adjuvant-challenged mice. We found that CPT-11 effectively inhibited T cell proliferation and Th1 and Th17 cell differentiation by inhibiting glycolysis in T cells. We also assessed CPT-11 efficacy in treating autoimmune diseases in models of experimental autoimmune encephalomyelitis and psoriasis. Finally, we proved that treatment of autoimmune diseases with CPT-11 did not suppress long-term immune surveillance for cancer. Taken together, these results show that CPT-11 is a promising immunosuppressive drug for autoimmune disease treatment.

MicroRNA-19b exacerbates systemic sclerosis through promoting Th9 cells.

Systemic sclerosis (SSc) is a chronic autoimmune disease characterized by fibrosis of the skin and multiple vital organs, but the immunological pathogenesis of SSc remains unclear. We show here that miR-19b promotes Th9 cells that exacerbate SSc. Specifically, miR-19b and interleukin (IL)-9 increase in CD4+ T cells in experimental SSc in mice induced with bleomycin. Inhibiting miR-19b reduces Th9 cells and ameliorates the disease. Mechanistically, transforming growth factor beta (TGF-ß) plus IL-4 activates pSmad3-Ser213 and TRAF6-K63 ubiquitination by suppressing NLRC3. Activated TRAF6 sequentially promotes TGF-ß-activated kinase 1 (TAK1) and nuclear factor κB (NF-κB) p65 phosphorylation, leading to the upregulation of miR-19b. Notably, miR-19b activated Il9 gene expression by directly suppressing atypical E2F family member E2f8. In patients with SSc, higher levels of IL9 and MIR-19B correlate with worse disease progression. Our findings reveal miR-19b as a key factor in Th9 cell-mediated SSc pathogenesis and should have clinical implications for patients with SSc.

Pathogenesis and treatment of Sjogren's syndrome: Review and update.

Sjogren's syndrome (SS) is a chronic autoimmune disease accompanied by multiple lesions. The main manifestations include dryness of the mouth and eyes, along with systemic complications (e.g., pulmonary disease, kidney injury, and lymphoma). In this review, we highlight that IFNs, Th17 cell-related cytokines (IL-17 and IL-23), and B cell-related cytokines (TNF and BAFF) are crucial for the pathogenesis of SS. We also summarize the advances in experimental treatment strategies, including targeting Treg/Th17, mesenchymal stem cell treatment, targeting BAFF, inhibiting JAK pathway, et al. Similar to that of SLE, RA, and MS, biotherapeutic strategies of SS consist of neutralizing antibodies and inflammation-related receptor blockers targeting proinflammatory signaling pathways. However, clinical research on SS therapy is comparatively rare. Moreover, the differences in the curative effects of immunotherapies among SS and other autoimmune diseases are not fully understood. We emphasize that targeted drugs, low-side-effect drugs, and combination therapies should be the focus of future research.

Reactive oxygen species formation and its effect on CD4+ T cell-mediated inflammation.

Reactive oxygen species (ROS) are produced both enzymatically and non-enzymatically in vivo. Physiological concentrations of ROS act as signaling molecules that participate in various physiological and pathophysiological activities and play an important role in basic metabolic functions. Diseases related to metabolic disorders may be affected by changes in redox balance. This review details the common generation pathways of intracellular ROS and discusses the damage to physiological functions when the ROS concentration is too high to reach an oxidative stress state. We also summarize the main features and energy metabolism of CD4+ T-cell activation and differentiation and the effects of ROS produced during the oxidative metabolism of CD4+ T cells. Because the current treatment for autoimmune diseases damages other immune responses and functional cells in the body, inhibiting the activation and differentiation of autoreactive T cells by targeting oxidative metabolism or ROS production without damaging systemic immune function is a promising treatment option. Therefore, exploring the relationship between T-cell energy metabolism and ROS and the T-cell differentiation process provides theoretical support for discovering effective treatments for T cell-mediated autoimmune diseases.

Interactions between neutrophils and T-helper 17 cells.

Neutrophils comprise the majority of immune cells in human peripheral circulation, have potent antimicrobial activities, and are clinically significant in their abundance, heterogeneity, and subcellular localization. In the past few years, the role of neutrophils as components of the innate immune response has been studied in numerous ways, and these cells are crucial in fighting infections, autoimmune diseases, and cancer. T-helper 17 (Th17) cells that produce interleukin 17 (IL-17) are critical in fighting infections and maintaining mucosal immune homeostasis, whereas they mediate several autoimmune diseases. Neutrophils affect adaptive immune responses by interacting with adaptive immune cells. In this review, we describe the physiological roles of both Th17 cells and neutrophils and their interactions and briefly describe the pathological processes in which these two cell types participate. We provide a summary of relevant drugs targeting IL-17A and their clinical trials. Here, we highlight the interactions between Th17 cells and neutrophils in diverse pathophysiological situations.

Signaling pathways involved in the biological functions of dendritic cells and their implications for disease treatment.

The ability of dendritic cells (DCs) to initiate and regulate adaptive immune responses is fundamental for maintaining immune homeostasis upon exposure to self or foreign antigens. The immune regulatory function of DCs is strictly controlled by their distribution as well as by cytokines, chemokines, and transcriptional programming. These factors work in conjunction to determine whether DCs exert an immunosuppressive or immune-activating function. Therefore, understanding the molecular signals involved in DC-dependent immunoregulation is crucial in providing insight into the generation of organismal immunity and revealing potential clinical applications of DCs. Considering the many breakthroughs in DC research in recent years, in this review we focused on three basic lines of research directly related to the biological functions of DCs and summarized new immunotherapeutic strategies involving DCs. First, we reviewed recent findings on DC subsets and identified lineage-restricted transcription factors that guide the development of different DC subsets. Second, we discussed the recognition and processing of antigens by DCs through pattern recognition receptors, endogenous/exogenous pathways, and the presentation of antigens through peptide/major histocompatibility complexes. Third, we reviewed how interactions between DCs and T cells coordinate immune homeostasis in vivo via multiple pathways. Finally, we summarized the application of DC-based immunotherapy for autoimmune diseases and tumors and highlighted potential research prospects for immunotherapy that targets DCs. This review provides a useful resource to better understand the immunomodulatory signals involved in different subsets of DCs and the manipulation of these immune signals can facilitate DC-based immunotherapy.

TGF-ß controls development of TCRγδ+CD8αα+ intestinal intraepithelial lymphocytes.

γδ intestinal intraepithelial lymphocytes (IELs) constitute the majority of IELs with unique CD8αα+ homodimers that are distinct from γδT cells in other tissues. However, it remains largely unclear how those cells develop. Here we show that transforming growth factor beta (TGF-ß) signaling controls the development of TCRγδ+CD8αα+ IELs. Deletion of TGF-ß receptors or Smad3 and Smad2 in bone marrow stem cells caused a deficiency of TCRγδ+CD8αα+ IELs in mixed bone marrow chimeric mice. Mechanistically, TGF-ß is required for the development of TCRγδ+CD8αα+ IELs thymic precursors (CD44-CD25- γδ thymocytes). In addition, TGF-ß signaling induced CD8α in thymic γδT cells and maintained CD8α expression and survival in TCRγδ+CD8αα+ IELs. Moreover, TGF-ß also indirectly controls TCRγδ+CD8αα+ IELs by modulating the function of intestinal epithelial cells (IECs). Importantly, TGF-ß signaling in TCRγδ+CD8αα+ IELs safeguarded the integrity of the intestinal barrier in dextran sulfate sodium (DSS)-induced colitis.

Single-cell immune profiling reveals immune responses in oral lichen planus.

Introduction: Oral lichen planus (OLP) is a common chronic inflammatory disorder of the oral mucosa with an unclear etiology. Several types of immune cells are involved in the pathogenesis of OLP. Methods: We used single-cell RNA sequencing and immune repertoire sequencing to characterize the mucosal immune microenvironment of OLP. The presence of tissue-resident memory CD8+ T cells are validated by multiplex immunofluorescence. Results: We generated a transcriptome atlas from four OLP biopsy samples and their paired peripheral blood mononuclear cells (PBMCs), and compared them with two healthy tissues and three healthy PBMCs samples. Our analysis revealed activated tissue-resident memory CD8+ T cells in OLP tissues. T cell receptor repertoires displayed apperant clonal expansion and preferrential gene pairing in OLP patients. Additionally, obvious BCR clonal expansion was observed in OLP lesions. Plasmacytoid dendritic cells, a subtype that can promote dendritic cell maturation and enhance lymphocyte cytotoxicity, were identified in OLP. Conventional dendritic cells and macrophages are also found to exhibit pro-inflammatory activity in OLP. Cell-cell communication analysis reveals that fibroblasts might promote the recruitment and extravasation of immune cells into connective tissue. Discussion: Our study provides insights into the immune ecosystem of OLP, serving as a valuable resource for precision diagnosis and therapy of OLP.

High fructose diet: A risk factor for immune system dysregulation.

Excessive intake of sweets is a predisposing factor for metabolic disorders, and fructose, as one of the major dietary sugars in the diet, has been shown to be a major cause of obesity, diabetes, and metabolic syndrome. These disorders are usually associated with immune dysfunction. Therefore, exploring the effects of a high fructose diet on the immune system may provide insight into the underlying mechanisms of these diseases. We synthesized the available evidence to suggest that excessive fructose intake disrupts the body's immune homeostasis by promoting immune cell metabolic rearrangements, alterations in gut microbial community structure, and intestinal barrier permeability. Indeed, not only does fructose itself affect immune system homeostasis, but its metabolites also have a profound influence. The metabolites from fructolysis are mainly produced in the small intestine and liver and subsequently enter the systemic circulation. Elevated levels of fructose metabolites, such as uric acid, FFAs, and lactate, are closely associated with oxidative stress and local tissue and organ inflammatory responses. In this review, we will focus on the link between fructose and inflammatory responses. In the meanwhile, we will also briefly summarize the studies of cancer development and immune escape mediated by fructose, as it might be beneficial for cancer immunotherapy.