Alantolactone alleviates collagen-induced arthritis and inhibits Th17 cell differentiation through modulation of STAT3 signalling

CONTEXT

Alantolactone, the bioactive component in Inula helenium L. (Asteraceae), exhibits multiple biological effects.

OBJECTIVE

We aimed to determine the anti-inflammatory effect of alantolactone in a collagen-induced arthritis (CIA) mouse model and its immunomodulatory effects on Th17 differentiation.

MATERIALS AND METHODS

A CIA mouse model was established with DBA/1 mice randomly divided into four groups (n = 6): healthy, vehicle and two alantolactone-treated groups (25 or 50 mg/kg), followed by oral administration of alantolactone to mice for 21 consecutive days after arthritis onset. The severity of CIA was evaluated by an arthritic scoring system and histopathological examination. Levels of cytokines and anti-CII antibodies as well as percentages of splenic Th17 and Th17 differentiation with or without alantolactone treatments (0.62, 1.2 or 2.5 μM) were detected with ELISA and flow cytometry, respectively. Western blot analysis was used to evaluate intracellular signalling in alantolactone-treated spleen cells.

RESULTS

In CIA mice, alantolactone at 50 mg/kg attenuated RA symptoms, including high arthritis scores, infiltrating inflammatory cells, synovial hyperplasia, bone erosion and levels of the proinflammatory cytokines TNF-α, IL-6 and IL-17A, but not IL-10 in paw tissues. Alantolactone also reduced the number of splenic Th17 cells and the capability of naïve CD4⁺ T cells to differentiate into the Th17 subset by downregulating STAT3/RORγt signalling by as early as 24 h of treatment.

DISCUSSION AND CONCLUSIONS

Alantolactone possesses an anti-inflammatory effect that suppresses murine CIA by inhibiting Th17 cell differentiation, suggesting alantolactone is an adjunctive therapeutic candidate to treat rheumatoid arthritis.

Homeostatic IL-13 in healthy skin directs dendritic cell differentiation to promote TH2 and inhibit TH17 cell polarization

The signals driving the adaptation of type 2 dendritic cells (DC2s) to diverse peripheral environments remain mostly undefined. We show that differentiation of CD11blo migratory DC2s-a DC2 population unique to the dermis-required IL-13 signaling dependent on the transcription factors STAT6 and KLF4, whereas DC2s in lung and small intestine were STAT6-independent. Similarly, human DC2s in skin expressed an IL-4 and IL-13 gene signature that was not found in blood, spleen and lung DCs. In mice, IL-13 was secreted homeostatically by dermal innate lymphoid cells and was independent of microbiota, TSLP or IL-33. In the absence of IL-13 signaling, dermal DC2s were stable in number but remained CD11bhi and showed defective activation in response to allergens, with diminished ability to support the development of IL-4+GATA3+ helper T cells (TH), whereas antifungal IL-17+RORγt+ TH cells were increased. Therefore, homeostatic IL-13 fosters a noninflammatory skin environment that supports allergic sensitization.

Gomisin M2 alleviates psoriasis‑like skin inflammation by inhibiting inflammatory signaling pathways

Psoriasis, a chronic inflammatory skin disease, is characterized by the excessive proliferation and impaired differentiation of epidermal keratinocytes and is accompanied by the increased infiltration of inflammatory cells. The condition requires long‑term treatment and has no definitive cure. Hence, supplements and therapeutic agents have been intensely investigated. Gomisin M2 (GM2), a lignan extracted from Schisandra chinensis (Turcz). Baill. (Schisandraceae; S. chinensis), has demonstrated diverse pharmacological properties, including anticancer, anti‑inflammatory and antiallergic effects. Based on these findings, the present study examined the effects of GM2 on an imiquimod (IMQ)‑induced psoriasis mouse model and on keratinocytes stimulated by tumor necrosis factor (TNF)‑α and interferon‑γ. IMQ was topically applied to the back skin of mice for 7 consecutive days, and the mice were orally administered CD. These results showed that the oral administration of GM2 suppressed the symptoms of psoriasis, as evidenced by reductions in skin thickness, psoriasis area severity index scores for psoriasis lesions, transepidermal water loss and myeloperoxidase (MPO)‑associated cell infiltration. Furthermore, GM2 reduced the pathologically increased levels of immunoglobulin G2a, MPO and TNF‑α in the serum and T helper (Th)1 and Th17 cell populations in the spleen. GM2 decreased the gene expression of inflammatory‑related cytokines and chemokines and inhibited the expression of signal transducer and activator of transcription 1 and nuclear factor‑κB in the activated keratinocytes. These results suggested that GM2 from S. chinensis is a potential therapeutic candidate to alleviate psoriasis‑like skin inflammation.

Effects of Recombinant IL-35-BCG on Treg/Th17 Cell Imbalance and Inflammatory Response in Asthmatic Newborn Mice Induced by RSV

Treg/Th17 cell imbalance and inflammatory response may occur in neonatal asthma. IL-35 and BCG have inhibitory effects on inflammatory responses in diseases. However, studies on neonatal asthma after combination of the two have not been reported so far. A respiratory syncytial virus (RSV)-induced neonatal asthma model was first developed in newborn mice. Pathological sections of lung tissue of asthmatic mice were observed by HE staining. Masson staining was used to observe the lung tissue and to compare the deposition of collagen fibers under bronchial epithelium in model mice. The expression of cytokines in serum was detected by ELISA. Giemsa staining analyzed each cell in bronchoalveolar lavage fluid (BALF). Flow cytometry was used to detect the differentiation and development of Treg and Th17 subgroups in BALF. The expression levels of inflammation-related factors were detected by RT-qPCR. Western blot was used to detect the expression of JNK pathway-related proteins. Recombinant IL-35-BCG improved the pathological response of asthmatic mice; inhibited the expression of IgE in serum, neutrophils, macrophages, and eosinophils in BALF; and increased the expression of lymphocytes. In addition, recombinant IL-35-BCG significantly inhibited Th17 differentiation, promoted Treg cell differentiation, and inhibited the expression of inflammatory factors in lung tissue homogenates, thereby reducing allergic airway inflammation. This process might be achieved by inhibiting the JNK signaling pathway. Recombinant IL-35-BCG can regulate Treg/Th17 cell imbalance and inflammatory response in asthmatic newborn mice induced by RSV through JNK signaling pathway, suggesting a new path to neonatal asthma treatment.

Small molecule allosteric inhibitors of RORγt block Th17-dependent inflammation and associated gene expression in vivo

Retinoic acid receptor-related orphan nuclear receptor (ROR) γt is a member of the RORC nuclear hormone receptor family of transcription factors. RORγt functions as a critical regulator of thymopoiesis and immune responses. RORγt is expressed in multiple immune cell populations including Th17 cells, where its primary function is regulation of immune responses to bacteria and fungi through IL-17A production. However, excessive IL-17A production has been linked to numerous autoimmune diseases. Moreover, Th17 cells have been shown to elicit both pro- and anti-tumor effects. Thus, modulation of the RORγt/IL-17A axis may represent an attractive therapeutic target for the treatment of autoimmune disorders and some cancers. Herein we report the design, synthesis and characterization of three selective allosteric RORγt inhibitors in preclinical models of inflammation and tumor growth. We demonstrate that these compounds can inhibit Th17 differentiation and maintenance in vitro and Th17-dependent inflammation and associated gene expression in vivo, in a dose-dependent manner. Finally, RORγt inhibitors were assessed for efficacy against tumor formation. While, RORγt inhibitors were shown to inhibit tumor formation in pancreatic ductal adenocarcinoma (PDAC) organoids in vitro and modulate RORγt target genes in vivo, this activity was not sufficient to delay tumor volume in a KP/C human tumor mouse model of pancreatic cancer.

Trans-Ned 19-Mediated Antagonism of Nicotinic Acid Adenine Nucleotide-Mediated Calcium Signaling Regulates Th17 Cell Plasticity in Mice

Nicotinic acid adenine dinucleotide phosphate (NAADP) is the most potent Ca2+ mobilizing agent and its inhibition proved to inhibit T-cell activation. However, the impact of the NAADP signaling on CD4+ T-cell differentiation and plasticity and on the inflammation in tissues other than the central nervous system remains unclear. In this study, we used an antagonist of NAADP signaling, trans-Ned 19, to study the role of NAADP in CD4+ T-cell differentiation and effector function. Partial blockade of NAADP signaling in naïve CD4+ T cells in vitro promoted the differentiation of Th17 cells. Interestingly, trans-Ned 19 also promoted the production of IL-10, co-expression of LAG-3 and CD49b and increased the suppressive capacity of Th17 cells. Moreover, using an IL-17A fate mapping mouse model, we showed that NAADP inhibition promotes conversion of Th17 cells into regulatory T cells in vitro and in vivo. In line with the results, we found that inhibiting NAADP ameliorates disease in a mouse model of intestinal inflammation. Thus, these results reveal a novel function of NAADP in controlling the differentiation and plasticity of CD4+ T cells.

Association between particulate matter containing EPFRs and neutrophilic asthma through AhR and Th17

BACKGROUND

Epidemiological data associate high levels of combustion-derived particulate matter (PM) with deleterious respiratory outcomes, but the mechanism underlying those outcomes remains elusive. It has been acknowledged by the World Health Organization that PM exposure contributes to more than 4.2 million all-cause mortalities worldwide each year. Current literature demonstrates that PM exacerbates respiratory diseases, impairs lung function, results in chronic respiratory illnesses, and is associated with increased mortality. The proposed mechanisms revolve around oxidative stress and inflammation promoting pulmonary physiological remodeling. However, our previous data found that PM is capable of inducing T helper cell 17 (Th17) immune responses via aryl hydrocarbon receptor (Ahr) activation, which was associated with neutrophilic invasion characteristic of steroid insensitive asthma.

METHODS

In the present study, we utilized a combination of microarray and single cell RNA sequencing data to analyze the immunological landscape in mouse lungs following acute exposure to combustion derived particulate matter.

RESULTS

We present data that suggest epithelial cells produce specific cytokines in the aryl hydrocarbon receptor (Ahr) pathway that inform dendritic cells to initiate the production of pathogenic T helper (eTh17) cells. Using single-cell RNA sequencing analysis, we observed that upon exposure epithelial cells acquire a transcriptomic profile indicative of increased Il-17 signaling, Ahr activation, Egfr signaling, and T cell receptor and co-stimulatory signaling pathways. Epithelial cells further showed, Ahr activation is brought on by Ahr/ARNT nuclear translocation and activation of tyrosine kinase c-src, Egfr, and subsequently Erk1/2 pathways.

CONCLUSIONS

Collectively, our data corroborates that PM initiates an eTh17 specific inflammatory response causing neutrophilic asthma through pathways in epithelial, dendritic, and T cells that promote eTh17 differentiation during initial PM exposure.

Response and recurrence correlates in individuals treated with neoadjuvant anti-PD-1 therapy for resectable oral cavity squamous cell carcinoma

Neoadjuvant PD-1 blockade may be efficacious in some individuals with high-risk, resectable oral cavity head and neck cancer. To explore correlates of response patterns to neoadjuvant nivolumab treatment and post-surgical recurrences, we analyzed longitudinal tumor and blood samples in a cohort of 12 individuals displaying 33% responsiveness. Pretreatment tumor-based detection of FLT4 mutations and PTEN signature enrichment favors response, and high tumor mutational burden improves recurrence-free survival. In contrast, preexisting and/or acquired mutations (in CDKN2A, YAP1, or JAK2) correlate with innate resistance and/or tumor recurrence. Immunologically, tumor response after therapy entails T cell receptor repertoire diversification in peripheral blood and intratumoral expansion of preexisting T cell clones. A high ratio of regulatory T to T helper 17 cells in pretreatment blood predicts low T cell receptor repertoire diversity in pretreatment blood, a low cytolytic T cell signature in pretreatment tumors, and innate resistance. Our study provides a molecular framework to advance neoadjuvant anti-PD-1 therapy for individuals with resectable head and neck cancer.

Effects of Molecular Iodine/Chemotherapy in the Immune Component of Breast Cancer Tumoral Microenvironment

Molecular iodine (I₂) induces apoptotic, antiangiogenic, and antiproliferative effects in breast cancer cells. Little is known about its effects on the tumor immune microenvironment. We studied the effect of oral (5 mg/day) I₂ supplementation alone (I₂) or together with conventional chemotherapy (Cht+I₂) on the immune component of breast cancer tumors from a previously published pilot study conducted in Mexico. RNA-seq, I₂ and Cht+I₂ samples showed significant increases in the expression of Th1 and Th17 pathways. Tumor immune composition determined by deconvolution analysis revealed significant increases in M0 macrophages and B lymphocytes in both I₂ groups. Real-time RT-PCR showed that I₂ tumors overexpress T-BET (p = 0.019) and interferon-gamma (IFNγ; p = 0.020) and silence tumor growth factor-beta (TGFβ; p = 0.049), whereas in Cht+I₂ tumors, GATA3 is silenced (p = 0.014). Preliminary methylation analysis shows that I₂ activates IFNγ gene promoter (by increasing its unmethylated form) and silences TGFβ in Cht+I₂. In conclusion, our data showed that I₂ supplements induce the activation of the immune response and that when combined with Cht, the Th1 pathways are stimulated. The molecular mechanisms involved in these responses are being analyzed, but preliminary data suggest that methylation/demethylation mechanisms could also participate.

Targeting DCs for Tolerance Induction: Don't Lose Sight of the Neutrophils

Chronic inflammatory disorders (CID), such as autoimmune diseases, are characterized by overactivation of the immune system and loss of immune tolerance. T helper 17 (Th17) cells are strongly associated with the pathogenesis of multiple CID, including psoriasis, rheumatoid arthritis, and inflammatory bowel disease. In line with the increasingly recognized contribution of innate immune cells to the modulation of dendritic cell (DC) function and DC-driven adaptive immune responses, we recently showed that neutrophils are required for DC-driven Th17 cell differentiation from human naive T cells. Consequently, recruitment of neutrophils to inflamed tissues and lymph nodes likely creates a highly inflammatory loop through the induction of Th17 cells that should be intercepted to attenuate disease progression. Tolerogenic therapy via DCs, the central orchestrators of the adaptive immune response, is a promising strategy for the treatment of CID. Tolerogenic DCs could restore immune tolerance by driving the development of regulatory T cells (Tregs) in the periphery. In this review, we discuss the effects of the tolerogenic adjuvants vitamin D3 (VD3), corticosteroids (CS), and retinoic acid (RA) on both DCs and neutrophils and their potential interplay. We briefly summarize how neutrophils shape DC-driven T-cell development in general. We propose that, for optimization of tolerogenic DC therapy for the treatment of CID, both DCs for tolerance induction and the neutrophil inflammatory loop should be targeted while preserving the potential Treg-enhancing effects of neutrophils.

Halofuginone functions as a therapeutic drug for chronic periodontitis in a mouse model

Periodontitis is an inflammatory disease caused by host immune response, resulting in a loss of periodontium and alveolar bone. Immune cells, such as T cells and macrophages, play a critical role in the periodontitis onset. Halofuginone, a natural quinazolinone alkaloid, has been shown to possess anti-fibrosis, anti-cancer, and immunomodulatory properties. However, the effect of halofuginone on periodontitis has never been reported. In this study, a ligature-induced mice model of periodontitis was applied to investigate the potential beneficial effect of halofuginone on periodontitis. We demonstrated that the administration of halofuginone significantly reduced the expression levels of pro-inflammatory cytokines (IL-1β, IL-6, and TNF-α) in vivo, and markedly suppressed immune cell infiltration into the infected sites. Furthermore, we also observed that halofuginone treatment blocked the T-helper 17 (Th17) cell differentiation in vivo and in vitro. We demonstrated for the first time that halofuginone alleviated the onset of periodontitis through reducing immune responses.

Surfactant protein A modulates the activities of the JAK/STAT pathway in suppressing Th1 and Th17 polarization in murine OVA-induced allergic asthma

Asthma is an allergic inflammatory lung disease affecting nearly 300 million people worldwide. To better understand asthma, new regulators must be identified. We conducted a study to investigate the effect and mechanisms of action of surfactant protein A (SPA) in OVA-induced asthmatic mice. Treatment with SPA delayed the onset of asthma, decreased its severity, as well as notably suppressed pro-inflammatory cytokine production. Furthermore, SPA-treated mice possessed more leukocytes; more CD4+ T cells infiltrated the spleen in the SPA-treated mice than in the control mice, and there were decreased percentages of Th1 and Th17 cells in vivo. In addition, expression levels of the T-bet (Th1 transcription factor) and RORγt (Th17 transcription factor) genes were significantly downregulated by SPA treatment. Moreover, SPA reduced the production and mRNA expression of pro-inflammatory cytokine mRNAs in activated T cells in vivo. Mechanistically, SPA could inhibit STAT1/4 and STAT3 phosphorylation, resulting in the differentiation of Th1 and suppression of Th17 cells, respectively. In the presence of CD3/CD28 expression, STAT1/4 and STAT3 were activated but suppressed by SPA, which was responsible for the augmentation of Th1 and Th17 differentiation. This result showed that SPA can effectively modulate the JAK/STAT pathway by suppressing Th1 and Th17 differentiation, thus preventing asthma. The present study reveals the novel immunomodulatory activity of SPA and highlights the importance of further investigating the effects of SPA on asthma.

Interferon-β Intensifies Interleukin-23-Driven Pathogenicity of T Helper Cells in Neuroinflammatory Disease

Interferon (IFN)-β is a popular therapy for multiple sclerosis (MS). However, 25-40% of patients are nonresponsive to this therapy, and it worsens neuromyelitis optica (NMO), another neuroinflammatory disease. We previously identified, in both NMO patients and in mice, that IFN-β treatment had inflammatory effects in T Helper (TH) 17-induced disease through the production of the inflammatory cytokine IL-6. However, other studies have shown that IFN-β inhibits the differentiation and function of TH17 cells. In this manuscript, we identified that IFN-β had differential effects on discrete stages of TH17 development. During early TH17 development, IFN-β inhibits IL-17 production. Conversely, during late TH17 differentiation, IFN-β synergizes with IL-23 to promote a pathogenic T cell that has both TH1 and TH17 characteristics and expresses elevated levels of the potent inflammatory cytokines IL-6 and GM-CSF and the transcription factor BLIMP. Together, these findings help resolve a paradox surrounding IFN-β and TH17-induced disease and illuminate the pathways responsible for the pathophysiology of NMO and MS patients who are IFN-β nonresponders.

Analysis of Iron and Iron-Interacting Protein Dynamics During T-Cell Activation

Recent findings have shown that iron is a powerful regulator of immune responses, which is of broad importance because iron deficiency is highly prevalent worldwide. However, the underlying reasons of why iron is needed by lymphocytes remain unclear. Using a combination of mathematical modelling, bioinformatic analysis and experimental work, we studied how iron influences T-cells. We identified iron-interacting proteins in CD4+ and CD8+ T-cell proteomes that were differentially expressed during activation, suggesting that pathways enriched with such proteins, including histone demethylation, may be impaired by iron deficiency. Consistent with this, iron-starved Th17 cells showed elevated expression of the repressive histone mark H3K27me3 and displayed reduced RORγt and IL-17a, highlighting a previously unappreciated role for iron in T-cell differentiation. Quantitatively, we estimated T-cell iron content and calculated that T-cell iron demand rapidly and substantially increases after activation. We modelled that these increased requirements will not be met during clinically defined iron deficiency, indicating that normalizing serum iron may benefit adaptive immunity. Conversely, modelling predicted that excess serum iron would not enhance CD8+ T-cell responses, which we confirmed by immunising inducible hepcidin knock-out mice that have very high serum iron concentrations. Therefore, iron deficiency impairs multiple aspects of T-cell responses, while iron overload likely has milder effects.

Oleanolic acid regulates the Treg/Th17 imbalance in gastric cancer by targeting IL-6 with miR-98-5p

BACKGROUND

Gastric cancer (GC) was a type of malignant tumor with a very high fatality rate. Oleanolic acid (OA) was a class of pentacyclic triterpenes which was proved to have anti-cancer activity. While the specific molecular mechanism of OA's role in inhibiting GC was not fully understood. This study aimed to explore how OA played an anti-cancer role in GC.

METHODS

Expression of miR-98-5p was examined using qPCR, and expression levels of Treg/Th17-related factors were evaluated using qPCR and western blot. Flow cytometry was conducted to assess the proportion of Treg cells and Th17 cells. Besides, dual luciferase reporter assay was performed to verify that IL-6 was a target of miR-98-5p.

RESULTS

Downregulation of miR-98-5p and upregulation of Treg/Th17-related factors were observed in GC tissues. What's more, the Treg/Th17 imbalance was found in PBMCs of GC patients. Overexpression of miR-98-5p promoted balance of Treg/Th17 cells via directly targeting IL-6 to downregulate expression of IL-6. Finally, OA could promote balance of Treg/Th17 cells by upregulating expression of miR-98-5p.

DISCUSSION

All our results proved that OA could promote balance of Treg/Th17 cells in GC by targeting IL-6 with miR-98-5p, indicating a potential drug for treatment of GC.

The MS Remyelinating Drug Bexarotene (an RXR Agonist) Promotes Induction of Human Tregs and Suppresses Th17 Differentiation In Vitro

The retinoid X receptor agonist bexarotene promotes remyelination in patients with multiple sclerosis. Murine studies have also demonstrated that RXR agonists have anti-inflammatory effects by enhancing the ability of all-trans-retinoic acid (atRA) to promote T-regulatory cell (Treg) induction and reduce Th17 differentiation in vitro. By stimulating human naïve CD4 T-cells in the presence of Treg or Th17 skewing cytokines, we show that bexarotene also tips the human Treg/Th17 axis in favor of Treg induction, but unlike murine cells this occurs independently of atRA and retinoic acid receptor signaling. Tregs induced in the presence of bexarotene express canonical markers of T-regulation and are functionally suppressive in vitro. Circulating Treg numbers did not increase in the blood of trial patients receiving bexarotene; we believe this is because Treg induction is likely to occur within tissues. These findings lend support to developing RXR agonists as treatments of autoimmune diseases, in particular multiple sclerosis.

Metabolic modeling of single Th17 cells reveals regulators of autoimmunity

Metabolism is a major regulator of immune cell function, but it remains difficult to study the metabolic status of individual cells. Here, we present Compass, an algorithm to characterize cellular metabolic states based on single-cell RNA sequencing and flux balance analysis. We applied Compass to associate metabolic states with T helper 17 (Th17) functional variability (pathogenic potential) and recovered a metabolic switch between glycolysis and fatty acid oxidation, akin to known Th17/regulatory T cell (Treg) differences, which we validated by metabolic assays. Compass also predicted that Th17 pathogenicity was associated with arginine and downstream polyamine metabolism. Indeed, polyamine-related enzyme expression was enhanced in pathogenic Th17 and suppressed in Treg cells. Chemical and genetic perturbation of polyamine metabolism inhibited Th17 cytokines, promoted Foxp3 expression, and remodeled the transcriptome and epigenome of Th17 cells toward a Treg-like state. In vivo perturbations of the polyamine pathway altered the phenotype of encephalitogenic T cells and attenuated tissue inflammation in CNS autoimmunity.

Polyamine metabolism is a central determinant of helper T cell lineage fidelity

Polyamine synthesis represents one of the most profound metabolic changes during T cell activation, but the biological implications of this are scarcely known. Here, we show that polyamine metabolism is a fundamental process governing the ability of CD4+ helper T cells (TH) to polarize into different functional fates. Deficiency in ornithine decarboxylase, a crucial enzyme for polyamine synthesis, results in a severe failure of CD4+ T cells to adopt correct subset specification, underscored by ectopic expression of multiple cytokines and lineage-defining transcription factors across TH cell subsets. Polyamines control TH differentiation by providing substrates for deoxyhypusine synthase, which synthesizes the amino acid hypusine, and mice in which T cells are deficient for hypusine develop severe intestinal inflammatory disease. Polyamine-hypusine deficiency caused widespread epigenetic remodeling driven by alterations in histone acetylation and a re-wired tricarboxylic acid (TCA) cycle. Thus, polyamine metabolism is critical for maintaining the epigenome to focus TH cell subset fidelity.

5,6,7,8-Tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine derivative attenuates lupus nephritis with less effect to thymocyte development

Retinoic‑acid‑receptor‑related orphan nuclear hormone receptor gamma t (RORγt), a critical transcriptional factor of Th17 cells, is a potential therapeutic target for Th17-mediated autoimmune diseases. In addition, RORγt is essential for thymocyte survival and lymph node development, and RORγt inhibition or deficiency causes abnormal thymocyte development, thymus lymphoma, and lymph node defect. Recent study demonstrated that specific regulation of Th17 differentiation related to the hinge region of RORγt. In this research, we investigated the effect of RORγt inhibitor, 5,6,7,8-tetrahydrobenzo[4,5]thieno[2,3-d]pyrimidine derivative (TTP), in the therapy of lupus nephritis and its safety on thymocyte development. We demonstrated that TTP repressed the development of Th17 cells and ameliorated the autoimmune disease manifestation in the pristane-induced lupus nephritis mice model. The treatment of TTP in the mice did not interfere with thymocyte development, including total thymocyte number and proportion of CD4+CD8+ double-positive populations in the thymus, and had no substantial effects on the pathogenesis of thymoma. The TTP had a stronger affinity with full-length RORγt protein compared with the truncated RORγt LBD region via surface plasmon resonance, which indicated TTP binding to RORγt beyond LBD region. Molecular docking computation showed that the best binding pocket of TTP to RORγt is located in the hinge region of RORγt. In summary, as a RORγt inhibitor, TTP had a potential to develop the clinical medicine for treating Th17-mediated autoimmune diseases with low safety risk for thymocyte development.

Traffic-related PM2.5 and diverse constituents disturb the balance of Th17/Treg cells by STAT3/RORγt-STAT5/Foxp3 signaling pathway in a rat model of asthma

Water-soluble ions (WSI) and organic extract (OE) in traffic-related particulate matter with aerodynamic diameters ≤ 2.5 μm (TRPM2.5) are potential risk factors for asthma exacerbation. Although CD4+ T lymphocytes mediated immune response is involved in the pathogenesis of asthma, the effect of WSI-TRPM2.5 and OE-TRPM2.5 on the balance of Th17/Treg cells in asthma remains poorly understood. In this study, the ovalbumin (OVA)-sensitized rats were repeatedly exposure to TRPM2.5 (3 mg/kg·bw), WSI-TRPM2.5 (1.8 mg/kg·bw, 7.2 mg/kg·bw) and OE-TRPM2.5 (0.6 mg/kg·bw, 2.4 mg/kg·bw) every three days for five times. The inflammation response and hyperemia edema were observed in the lung and trachea tissues. DNA methylation levels of STAT3 and RORγt genes in rats with WSI-TRPM2.5 and OE-TRPM2.5 treatment were decreased. DNA methylation level in STAT5 gene tended to decrease, with no change observed on Foxp3 expression. WSI-TRPM2.5 and OE-TRPM2.5 enhanced the mRNA and protein expression of STAT3 and RORγt while inhibited the expression of STAT5 and Foxp3, which may contribute to the imbalance of Th17/Treg cells (P < 0.05). More importantly, recovered balance of Th17/Treg cell subsets, upregulated p-STAT5 and Foxp3 expression and reduced p-STAT3 and RORγt levels were observed after 5-Aza treatment. Our results demonstrate that the STAT3/RORγt-STAT5/Foxp3 signaling pathway is involved in asthma exacerbation induced by WSI-TRPM2.5 and OE-TRPM2.5 through disrupting the balance of Th17/Treg cells. The alteration of DNA methylation of STAT3, STAT5, and RORγt genes may be involved in asthma exacerbation as well.

5-Aza-2-deoxycytidine alleviates the progression of primary biliary cholangitis by suppressing the FoxP3 methylation and promoting the Treg/Th17 balance

Primary biliary cholangitis (PBC) is a common autoimmune liver disease manifested by the infiltration of CD4+ T cells, and the subsequent targeted injury of biliary epithelial cells (BECs). As important components of CD4 subsets, the Treg/Th17 axis maintains an immunological balance between self-tolerance and inflammation in the liver microenvironment. However, the role and regulatory mechanism of the Treg/Th17 axis in PBC remain unclear. In this study, we examined the Treg/Th17 axis in PBC patients and found that the Treg/Th17 axis was imbalanced in PBC at both the transcriptional and cellular levels, with Treg being a weak candidate, which correlates with the PBC progression. This imbalanced Treg/Th17 axis was likely to be affected by the FoxP3 hypermethylation, which was related to the increase of DNA methyltransferase. Furthermore, the effect of 5-Aza-2-deoxycytidine (DAC)-mediated FoxP3 demethylation on PBC mice was investigated. We verified that DAC significantly suppressed the FoxP3 methylation and rebuilt the Treg/Th17 balance, resulting in the alleviation of liver lesions and inflammation. Taken together, our data indicate that DAC plays a positive role in alleviating the progression of PBC through the inhibition of DNA methylation of FoxP3 to rebuild the balanced Treg/Th17 axis. DAC could be considered as a potential candidate for the development of new anti-inflammation strategies in the treatment of PBC.

The Ability of AhR Ligands to Attenuate Delayed Type Hypersensitivity Reaction Is Associated With Alterations in the Gut Microbiota

Aryl hydrocarbon receptor (AhR) is a ligand-activated transcription factor that regulates T cell function. The aim of this study was to investigate the effects of AhR ligands, 2,3,7,8-Tetrachlorodibenzo-p-dioxin (TCDD), and 6-Formylindolo[3,2-b]carbazole (FICZ), on gut-associated microbiota and T cell responses during delayed-type hypersensitivity (DTH) reaction induced by methylated bovine serum albumin (mBSA) in a mouse model. Mice with DTH showed significant changes in gut microbiota including an increased abundance of Bacteroidetes and decreased Firmicutes at the phylum level. Also, there was a decrease in Clostridium cluster XIV and IV, which promote anti-inflammatory responses, and an increase in Prevotella copri that facilitates pro-inflammatory responses. Interestingly, treatment of mice with TCDD attenuated the DTH response, induced Tregs, suppressed Th17 cells in the mesenteric lymph nodes (MLNs), and reversed the gut microbiota composition toward normalcy. In contrast, FICZ exacerbated the DTH response, induced heightened Th17 cells, and failed to cause a major shift in gut microbiota. Furthermore, TCDD but not FICZ caused an increase in the levels of short-chain fatty acids (SCFA), n-butyric acid, and acetic acid. Administration of sodium butyrate into mice with DTH suppressed the response, increased Tregs, and reduced Th17 cells IL17. Butyrate also caused an increase in the abundance of Clostridium and a decrease in Prevotella. Lastly, TCDD, as well as butyrate but not FICZ, were able to inhibit proinflammatory Histone deacetylases (HDACs) class I and II. Together, our data suggest that AhR ligands, such as TCDD that suppress DTH response, may mediate this effect by reversing the gut dysbiosis induced during this inflammatory response, while FICZ may fail to suppress the DTH response because of its inability to overturn the dysbiosis.

Pro-resolving lipid mediator lipoxin A4 attenuates neuro-inflammation by modulating T cell responses and modifies the spinal cord lipidome

The chronic neuro-inflammatory character of multiple sclerosis (MS) suggests that the natural process to resolve inflammation is impaired. This protective process is orchestrated by specialized pro-resolving lipid mediators (SPMs), but to date, the role of SPMs in MS remains largely unknown. Here, we provide in vivo evidence that treatment with the SPM lipoxin A4 (LXA4) ameliorates clinical symptoms of experimental autoimmune encephalomyelitis (EAE) and inhibits CD4+ and CD8+ T cell infiltration into the central nervous system (CNS). Moreover, we show that LXA4 potently reduces encephalitogenic Th1 and Th17 effector functions, both in vivo and in isolated human T cells from healthy donors and patients with relapsing-remitting MS. Finally, we demonstrate that LXA4 affects the spinal cord lipidome by significantly reducing the levels of pro-inflammatory lipid mediators during EAE. Collectively, our findings provide mechanistic insight into LXA4-mediated amelioration of neuro-inflammation and highlight the potential clinical application of LXA4 for MS.

Glaucocalyxin A suppresses inflammatory responses and induces apoptosis in TNF-a-induced human rheumatoid arthritis via modulation of the STAT3 pathway

The pathogenesis of rheumatoid arthritis (RA) is characterized by synoviocyte hyperplasia and proinflammatory cytokine secretion, as well as the destruction of cartilage and bone. Glaucocalyxin A (GLA) is an alkaloid derived from a Chinese medicinal plant that exhibits anti-inflammatory, anti-tumor and neuroprotective properties. We investigated the effects of GLA on RA-fibroblast-like synoviocytes (FLS cells), and collagen-induced arthritis (CIA), and further explored the underlying mechanisms. GLA inhibited TNF-a-induced RA-FLS proliferation, increased apoptotic ratios and upregulated levels of caspase-3, cleaved PARP, and Bax. GLA also inhibited the expression of IL-10, IL-1β, and IL-6 in vitro. Levels of p-STAT3 were downregulated in a dose-dependent manner. Over-expression of STAT3 partly neutralized the GLA-mediated elevation of caspase-3 and cleaved PARP levels as well as the downregulation of IL-10, IL-1B and IL-6 expression levels. This suggests that GLA inactivated the STAT3 pathway. Furthermore, the production of inflammatory cytokines in RA-FLS and a CIA rat model were inhibited effectively by GLA. Taken together, our data suggest that GLA is a potential long-term therapeutic agent for patients with RA.