Potential role of Th17 cells in the pathogenesis of inflammatory bowel disease

The etiopathology of inflammatory bowel disease （IBD） remains elusive. Accumulating evidence suggests that the abnormality of innate and adaptive immunity responses plays an important role in intestinal inflam- mation. IBD including Crohn＇s disease （CD） and ulcerative colitis （UC） is a chronic inflammatory disease of the gastrointestinal tract, which is implicated in an inappropriate and overactive mucosal immune response to luminal flora. Traditionally, CD is regarded as a Thl- mediated inflammatory disorder while UC is regarded as a Th2-1ike disease. Recently, Th17 cells were identified as a new subset of T helper cells unrelated to Thl or Th2 cells, and several cytokines [e.g. interleukin （IL）-21, IL-23] are involved in regulating their activation and differentiation. They not only play an important role in host defense against extracellular pathogens, but are also associated with the development of autoimmunity and inflammatory response such as IBD. The identification of Th17 cells helps us to explain some of the anomalies seen in the Thl/Th2 axis and has broadened our understanding of the immunopathological effects of Th17 cells in the development of IBD.

Rapamycin ameliorates experimental autoimmune uveoretinitis by inhibiting Th1/Th2/Th17 cells and upregulating CD4+CD25+ Foxp3 regulatory T cells

· AIM: To determine the effects of rapamycin on experimental autoimmune uveoretinitis(EAU) and investigate of role of rapamycin on T cell subsets in the disease.·METHODS: EAU was induced in rats using peptides1169 to 1191 of the interphotoreceptor binding protein(IRBP). Rapamycin(0.2 mg/kg/d) was administrated by intraperitoneal injection for a consecutive 7d after immunization. Th1/Th2/Th17 cytokines, TGF-β1, and IL-6produced by lymphocyteswere measured by ELISA, while Th17 cells and CD4 +CD25 + regulatory T cells(Tregs)from rat spleen were detected by flow cytometry.·RESULTS: Intraperitoneal treatment immediately after immunization dramatically ameliorated the clinical course of EAU. Clinical responses were associated with reduced retinal inflammatory cell infiltration and tissue destruction. Rapamycin induced suppression of Th1/Th2/Th17 cytokines, including IFN-γ, IL-2, IL-17, IL-4, and IL-10 release from T lymphocytes of EAU rats, in vitro.Rapamycin also significantly increased TGF-β1production but had no effect on IL-6 productionof T lymphocytes from EAU rats in vitro. Furthermore,rapamycin decreased the ratio of Th17 cells/CD4 +T cells and upregulated Tregs in EAU, as detected by flow cytometry.·CONCLUSION: Rapamycin effectively interferes with T cell mediated autoimmune uveitis by inhibiting antigen-specific T cell functions and enhancing Tregs in EAU.Rapamycin is a promising new alternative as an adjunct corticosteroid-sparing agent for treating uveitis.

Correlation between circulating myeloid-derived suppressor cells and Th17 cells in esophageal cancer

AIM: To perform a comprehensive investigation into the potential correlation between circulating myeloidderived suppressor cells (MDSCs) and Th17 cells in esophageal cancer (ECA). METHODS: A total of 31 patients newly diagnosed with ECA and 26 healthy subjects were included in the current study. The frequencies of MDSCs and Th17 cells in peripheral blood were determined by flow cytometry. The mRNA expression of cytokines, arginase 1 (Arg1) and inducible NO synthase (iNOS) in peripheral blood mononuclear cells (PBMCs) and plasma Arg1 were assessed by real-time polymerase chain reaction and enzyme-linked immunosorbent assay, respectively. RESULTS: There was an increased prevalence of MDSCs in the peripheral blood from ECA patients (15.21% ± 2.25%) when compared with healthy control (HC) (1.10% ± 0.12%, P < 0.0001). The plasma levels of Arg1 in ECA patients were significantly higher than those in HC (28.28 ± 4.10 ng/mL vs 9.57 ± 1.51 ng/ mL, P=0.0003). iNOS mRNA levels in the peripheral blood of ECA patients also showed a threefold increase compared with HC (P=0.0162). The frequencies of Th17 cells (CD4 + IL-17A + ) were significantly elevated in ECA patients versus HC (3.50% ± 0.33% vs 1.82% ± 0.19%, P=0.0001). Increased mRNA expression of IL-17 and ROR-γt was also observed in ECA patients compared with HC (P=0.0041 and P=0.0004, respectively), while the mRNA expression of IL-6 and tumor necrosis factor-α (TNF-α) showed significant decreases (P=0.0049 and P < 0.0001, respectively). No obvious correlations were found between the frequencies of MDSCs and Th17 cells in the peripheral blood from ECA patients(r=-0.1725, P=0.3534). Arg1 mRNA levels were positively correlated with levels of IL-6 (r=0.6404, P=0.0031) and TNF-α (r=0.7646, P=0.0001). Similarly, iNOS mRNA levels were also positively correlated with levels of IL-6 (r=0.6782, P=0.0007) and TNF-α (r=0.7633, P < 0.0001). CONCLUSION: This study reveals the relationship between circulating MDSCs and Th17 cells, which may lead to new immunotherapy approaches for ECA based on the associated metabolites and cytokines.

Silencing of <i>ERK2</i>with Small Interference RNA Regulates the Expression of CXCL1 in Th17 Cell

Patients with steroid-resistant asthma had their monocyte-derived TH17 cells collected. The expression levels of ERK2 in the TH17 were silenced and inhibited using ERK2 specific small interfering RNA (siRNA). By screening of CXCL1 and IL-17A in the TH17 culture supernatant, the expression levels of ERK2 and CXCL1 were determined. Using targeted siRNA to inhibit ERK2, the expression of ERK2 in the TH17 was reduced. Furthermore, inhibiting ERK2 hindered CXCL1 expression and decreased CXCL1 and IL-17A production. These findings suggest that ERK2 is involved in the synthesis of CXCL1 and IL-17A, two proteins that play a key role in the pathogenesis of hormone-resistant asthma.

Th17 Cells and Tregs in HTLV-1 Infection

HTLV-1(human T-lymphotropic virus type 1)causes chronic infection ofhuman T lymphocytes.HTLV-1 infection is known to be related to multiple diseases,including neoplastic growth of HTLV-1-infected T cells(ATL)and neoplastic inflammatory conditions,such as HTLV-1-associated myelopathy/tropical spastic paraparesis(HAM/TSP),Sjogren's syndrome with arthritis,polymyositis uveitis,and bronchoalveolitis.Regulatory T cells(Tregs)regulate inflammatory cells,such as Th17 cells.The purpose of this study was to evaluate Tregs and Th17 cells,as well as the expression of related transcription factors(ROR-γ1 and FOXP3)and cytokines(IL-10,TGF-β,IL-6,and IL-17A)in HTLV-1 infection.

Restoring the Treg cell to Th17 cell ratio may alleviate HBV-related acute-on-chronic liver failure

AIM: To investigate the role of T helper 17 cells (Th17) and regulatory T cells (Treg) in hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACLF).METHODS: We enrolled 79 patients with HBV infection into the study, 50 patients with HBV-related ACLF and 29 patients with chronic hepatitis B (CHB), from the First Affiliated Hospital of Medical College from January 2009 to June 2012. The ACLF patients were diagnosed according to the criteria recommended by The 19th Conference of the Asian Pacific Association for the Study of the Liver in 2009. Twenty healthy individuals with a similar gender and age structures to the two patient groups were also included as the normal controls (NC). Of the 50 ACLF patients, 28 were subsequently classified as non-survivors: 19 patients died from multiorgan failure, 3 underwent liver transplantation, and 6 discontinued therapy during follow-up because of financial reasons. The remaining 22 ACLF patients whose liver and anticoagulation function recovered to nearly normal levels within the next 6 mo were classified as survivors. The number of circulating Treg and Th17 cells was determined upon diagnosis and during the 8th week of follow-up through flow cytometry. RESULTS: The percentage of circulating Treg cells in the ACLF group was significantly higher than that in the CHB group (5.50% ± 1.15% vs 3.30% ± 1.13%, P < 0.01). The percentages of circulating Th17 cells in the ACLF and the CHB groups were significantly higher than that in the NC group (6.32% ± 2.22% vs 1.56% ± 0.44%, P < 0.01; 3.53% ± 1.65% vs 1.56% ± 0.44%, P < 0.01). No significant difference in Treg cell to Th17 cell ratio was observed between the ACLF group and the CHB group (0.98 ± 0.44 vs 1.12 ± 0.64, P = 0.991), whereas those in the two HBV infection groups were significantly lower than that in the NC group (1.85 ± 1.22; both P < 0.01). The percentage of Treg cells in the survivors during the 8th week of follow-up was significantly lower than that during peak ACLF severity [total bilirubin (TBIL) peak] (3.45% ± 0.97% vs 5.18% ± 1.02%, P < 0.01). The percentage of Th17 cells in survivors during the 8th week of follow-up was significantly lower than that during the peak TBIL (2.89% ±0.60% vs 5.24% ± 1.46%; P < 0.01). The Treg cell to Th17 cell ratio during the 8 th week of follow-up was significantly higher than that during the TBIL peak (1.22 ± 0.36 vs 1.10 ± 0.54; P < 0.05). CONCLUSION: Restoring the Treg cell to Th17 cell ratio during the follow-up phase of ACLF could maintain the immune system at a steady state, which favours good prognosis.

Faecalibacterium prausnitzii supernatant ameliorates dextran sulfate sodium induced colitis by regulating Th17 cell differentiation

AIM: To explore the preventive and therapeutic effects of Faecalibacterium prausnitzii(F. prausnitzii) supernatant on dextran sulfate sodium(DSS) induced colitis in mice.METHODS: Forty C57BL/6J male mice were randomlydivided into four groups: control group, model group, treatment group, and prevention group. Mice were weighed daily. On day 10, the colon length was measured, the colorectal histopathologic damage score(HDS) was assessed, and plasma interleukin(IL)-17 A, IL-6, and IL-4 levels were detected by enzyme-linked immunosorbent assay. The expression of transcription factor retinoic acid-related orphan receptor-γt(RORγt) and IL-17 A in colon inflammatory mucosa tissue were determined by immunohistochemical assay, and the expression levels of RORγt m RNA, IL-17 A m RNA, and IL-6 m RNA were detected by real-time quantitative polymerase chain reaction(PCR). The proportion of Th17 in mononuclear cells in spleen was assayed by fluorescence activated cell sorter. RESULTS: When compared with the model group, the colon length(P < 0.05) and body weight(P < 0.01) in the treatment and prevention groups were significantly increased, and the colon HDS was decreased(P < 0.05 and P < 0.01). There was no statistical difference between the treatment group and prevention group. After treatment with F. prausnitzii supernatant, the plasma levels of IL-17 A and IL-6(P < 0.05), the protein and m RNA expression of IL-17 A and RORγt, and the Th17 cell ratio of spleen cells(P < 0.01) were significantly decreased compared to the model group. Plasma IL-4 level in the prevention group was significantly higher than that in the model group(P < 0.05), but there was no significant difference between these two groups in the expression of IL-6 in both the plasma and colon mucosa tissues.CONCLUSION: F. prausnitzii supernatant exerts protective and therapeutic effects on DSS-induced colitis in mice, probably via inhibition of Th17 differentiation and IL- 17A secretion in the plasma and colon mucosa tissues. It can also improve colitis in mice by downregulating IL-6 and prevent colitis by upregulating IL-4.

Treg/Th17 cell balance and phytohaemagglutinin activation of T lymphocytes in peripheral blood of systemic sclerosis patients

AIM To investigate T-cell activation, the percentage of peripheral T regulatory cells(Tregs), Th17 cells and the circulating cytokine profile in systemic sclerosis(SSc).METHODS We enrolled a total of 24 SSc patients and 16 healthy controls in the study and divided the patients as having diffuse cutaneous SSc(dc SSc, n = 13) or limited cutaneous SSc(lc SSc, n = 11). We performed a further subdivision of the patients regarding the stage of the disease-early, intermediate or late. Peripheral venous blood samples were collected from all subjects. We performed flow cytometric analysis of the activationcapacity of T-lymphocytes upon stimulation with PHA-M and of the percentage of peripheral Tregs and Th17 cells in both patients and healthy controls. We used ELISA to quantitate serum levels of human interleukin(IL)-6, IL-10, tissue growth factor-β1(TGF-β1), and IL-17 A.RESULTS We identified a decreased percentage of CD3+CD69+ cells in PHA-stimulated samples from SSc patients in comparison with healthy controls(13.35% ± 2.90% vs 37.03% ± 2.33%, P < 0.001). However, we did not establish a correlation between the down-regulated CD3+CD69+ cells and the clinical subset, nor regarding the stage of the disease. The activated CD4+CD25+ peripheral lymphocytes were represented in decreased percentage in patients when compared to controls(6.30% ± 0.68% vs 9.36% ± 1.08%, P = 0.016). Regarding the forms of the disease, dc SSc patients demonstrated lower frequency of CD4+CD25+ T cells against healthy subjects(5.95% ± 0.89% vs 9.36% ± 1.08%, P = 0.025). With regard to Th17 cells, our patients demonstrated increased percentage in comparison with controls(18.13% ± 1.55% vs 13.73% ± 1.21%, P = 0.031). We detected up-regulated Th17 cells within the lc SSc subset against controls(20.46% ± 2.41% vs 13.73% ± 1.21%, P = 0.025), nevertheless no difference was found between dc SSc and lc SSc patients. Flow cytometric analysis revealed an increased percentage of CD4+CD25-Foxp3+ in dc SSc patients compared to controls(10.94% ± 1.65% vs 6.88% ± 0.91, P = 0.032). Regarding the peripheral cytokine profile, we detected raised levels of IL-6 [2.10(1.05-4.60) pg/m L vs 0.00 pg/m L, P < 0.001], TGF-β1(19.94 ± 3.35 ng/m L vs 10.03 ± 2.25 ng/m L, P = 0.02), IL-10(2.83 ± 0.44 pg/m L vs 0.68 ± 0.51 pg/m L, P = 0.008), and IL-17 A [6.30(2.50-15.60) pg/m L vs 0(0.00-0.05) pg/m L, P < 0.001] in patients when compared to healthy controls. Furthermore, we found increased circulating IL-10, TGF-β, IL-6 and IL-17 A in the lc SSc subset vs control subjects, as it follows: IL-10(3.32 ± 0.59 pg/m L vs 0.68 ± 0.51 pg/m L, P = 0.003), TGF-β1(22.82 ± 4.99 ng/m L vs 10.03 ± 2.25 ng/m L, P = 0.031), IL-6 [2.08(1.51-4.69) pg/m L vs 0.00 pg/m L, P < 0.001], and IL-17 A [14.50(8.55-41.65) pg/m L vs 0.00(0.00-0.05) pg/m L, P < 0.001]. Furthermore, circulating IL-17 A was higher in lc SSc as opposed to dc SSc subset(31.99 ± 13.29 pg/m L vs 7.14 ± 3.01 pg/m L, P = 0.008). Within the dc SSc subset, raised levels of IL-17 A and IL-6 were detected vs healthy controls: IL-17 A [2.60(0.45-9.80) pg/m L vs 0.00(0.00-0.05) pg/m L, P < 0.001], IL-6 [2.80(1.03-7.23) pg/m L vs 0.00 pg/m L, P < 0.001]. Regarding the stages of the disease, TGF-β1 serum levels were increased in early stage against late stage, independently from the SSc phenotype(30.03 ± 4.59 ng/m L vs 13.08 ± 4.50 ng/m L, P = 0.017).CONCLUSION It is likely that the altered percentage of Th17 and CD4+CD25-Fox P3+ cells along with the peripheral cytokine profile in patients with SSc may play a key role in the pathogenesis of the disease.

Higher Viral Load and Prolonged Viral Shedding Period is Associated with Impaired Th17 Cell Response in Patients with H1N1 Influenza A

Objective To explore whether age,disease severity,cytokines and lymphocytes in H1N1 influenza A patients correlate with viral load and clearance.Methods Total of 70 mild and 16 severe patients infected with H1N1 influenza A virus were enrolled in this study.Results It was found that the patients under 14 years old and severe patients displayed significantly higher viral loads and prolonged viral shedding periods compared with the patients over 14 years old and mild patients,respectively(P < 0.05).Moreover,the patients under 14 years old and severe patients displayed significantly lower Th17 cell frequency than the patients over 14 years old and mild patients(P < 0.01).The viral shedding period inversely correlated with the frequency of IL-17+IFN-γ-CD4+ T cells.Additionally,the decreased concentration of serum TGF-β correlated with the decreased frequency of IL-17+IFN-γ-CD4+ T cells.Conclusions Both younger and severe patients are associated with higher viral loads and longer viral shedding periods,which may partially be attributed to the impaired Th17 cell response.

The Expression of IL-27, Th17 Cells and Treg Cells in Peripheral Blood of Patients with Allergic Rhinitis

Objective: To explore the expression of IL-27, Th17 cells and CD4+CD25+ regulatory T cells (Treg) as well as its associated cytokines in peripheral blood of patients with allergic rhinitis (AR). Method: From March 2012 to May, the peripheral blood of 24 cases of AR patients (AR group) and 16 cases of healthy volunteers (control group) was collected, and the percentage of Th17 cells and Treg cells in the peripheral blood was detected by flow cytometry (FCM);the levels of IL-27, IL-17 and IL-10 in serum was detected by ELISA. Result: The percentage of Th17 cells in AR group and the control group was 1.76% ± 0.60% and 0.59% ± 0.17%, respectively. It was higher in AR group than in control group, and the difference between two groups was statistically significant (P 0.05). Conclusion: In the peripheral blood of AR patients there was a reduction of IL-27 level and imbalance of Th17/Treg cell function. IL-27 on Th17/Treg cells adjustment may play an important role on the pathogenesis of the AR.

Rheum palmatum L. and Salvia miltiorrhiza Bge. Alleviates Acute Pancreatitis by Regulating Th17 Cell Differentiation: An Integrated Network Pharmacology Analysis, Molecular Dynamics Simulation and Experimental Validation

Objective: To identify the core targets of Rheum palmatum L. and Salvia miltiorrhiza Bge.,(Dahuang-Danshen, DH-DS) and the mechanism underlying its therapeutic efficacy in acute pancreatitis(AP)using a network pharmacology approach and validate the findings in animal experiments. Methods: Network pharmacology analysis was used to elucidate the mechanisms underlying the therapeutic effects of DH-DS in AP. The reliability of the results was verified by molecular docking simulation and molecular dynamics simulation.Finally, the results of network pharmacology enrichment analysis were verified by immunohistochemistry,Western blot analysis and real-time quantitative PCR, respectively. Results: Sixty-seven common targets of DH-DS in AP were identified and mitogen-activated protein kinase 3(MAPK3), Janus kinase 2(JAK2), signal transducer and activator of transcription 3(STAT3), protein c-Fos(FOS) were identified as core targets in the protein interaction(PPI) network analysis. Gene ontology analysis showed that cellular response to organic substance was the main functions of DH-DS in AP, and Kyoto Encyclopedia of Genes and Genomes analysis showed that the main pathway included Th17 cell differentiation. Molecular docking simulation confirmed that DH-DS binds with strong affinity to MAPK3, STAT3 and FOS. Molecular dynamics simulation revealed that FOS-isotanshinone Ⅱ and STAT3-dan-shexinkum d had good binding capacity. Animal experiments indicated that compared with the AP model group, DH-DS treatment effectively alleviated AP by inhibiting the expression of interleukin-1β, interleukin-6 and tumor necrosis factor-α, and blocking the activation of Th17 cell differentiation(P<0.01). Conclusion: DH-DS could inhibit the expression of inflammatory factors and protect pancreatic tissues,which would be functioned by regulating Th17 cell differentiation-related m RNA and protein expressions.

Regulation of TH17 cell differentiation by innate immune signals

Upon antigen stimulation, naive T helper cells differentiate into distinct lineages to attain specialized properties and effector functions. TH17 cells, a recently identified lineage of CD4＋ effector T cells, play a key role in the immune defense against fungi and extracellular bacteria, but also contribute to the pathogenesis of many autoimmune conditions. The differentiation of TH 17 cells is orchestrated by an intricate network of signaling pathways and transcriptional regulators in T cells. While the involvement of T cell-intrinsic pathways has been described extensively, we are just beginning to appreciate how TH17 cell development is shaped by extrinsic pathways, espec- ially the innate immune signals. Dendritic cells （DCs）, the most important cell type to bridge innate and adaptive immunity, drive TH17 cell differentiation by providing antigenic, costimulatory and cytokine signals. This is mediated by the recognition of innate and inflam- matory signals by DCs via pattern recognition receptors, cytokine receptors and other immunomodulatory receptors that in turn activate the intracellular signaling network. In particular, p38a MAP kinase has emerged as a critical pathway to program DC-dependent TH17 cell differentiation by integrating multiple instructive signals in DCs. Here, we summarize the current knowledge on the mechanisms by which DC-derived innate immune signals drive TH17 cell differentiation.

Intricacies of TGF-βsignaling in Treg and Th17 cell biology

Balanced immunity is pivotal for health and homeostasis.CD4+helper T(Th)cells are central to the balance between immune tolerance and immune rejection.Th cells adopt distinct functions to maintain tolerance and clear pathogens.Dysregulation of Th cell function often leads to maladies,including autoimmunity,inflammatory disease,cancer,and infection.Regulatory T(Treg)and Th17 cells are critical Th cell types involved in immune tolerance,homeostasis,pathogenicity,and pathogen clearance.It is therefore critical to understand how Treg and Th17 cells are regulated in health and disease.Cytokines are instrumental in directing Treg and Th17 cell function.The evolutionarily conserved TGF-β(transforming growth factor-β)cytokine superfamily is of particular interest because it is central to the biology of both Treg cells that are predominantly immunosuppressive and Th17 cells that can be proinflammatory,pathogenic,and immune regulatory.How TGF-βsuperfamily members and their intricate signaling pathways regulate Treg and Th17 cell function is a question that has been intensely investigated for two decades.Here,we introduce the fundamental biology of TGF-βsuperfamily signaling,Treg cells,and Th17 cells and discuss in detail how the TGF-βsuperfamily contributes to Treg and Th17 cell biology through complex yet ordered and cooperative signaling networks.

microRNAs: critical regulators in Th17 cells and players in diseases

microRNAs are a novel group of small,conserved,non-coding RNA molecules that are present in all species.These molecules post-transcriptionally regulate gene expression by targeting mRNAs for degradation or by repressing the translation of the mRNAs.A good understanding of miRNA-mediated gene regulation is critical to gain a comprehensive view of many physiological processes and disease states.Emerging evidence demonstrates that miRNAs play an important role in the differentiation and function of the adaptive immune system.This review provides an overview of the diverse functions of miRNAs in modulating immune responses and in immune cell development,particularly the development of Th17 cells,and explores the involvement of miRNAs in several autoimmune diseases including multiple sclerosis(MS),rheumatoid arthritis(RA),inflammatory bowel disease(IBD)and diabetes.

The histone H3 lysine-27 demethylase Jmjd3 plays a critical role in specific regulation of Th17 cell differentiation

Interleukin(IL)17-producing T helper(Th17)cells play critical roles in the clearance of extracellular bacteria and fungi as well as the pathogenesis of various autoimmune diseases,such as multiple sclerosis,psoriasis,and ulcerative colitis.Although a global transcriptional regulatory network of Th17 cell differentiation has been mapped recently,the participation of epigenetic modifications in the differentiation process has yet to be elucidated.We demonstrated here that histone H3 lysine-27(H3K27)demethylation,predominantly mediated by the H3K27 demethylase Jmjd3,crucially regulated Th17 cell differentiation.Activation of naı¨ve CD41 T cells immediately induced high expression of Jmjd3.Genetic depletion of Jmjd3 in CD41 T cells specifically impaired Th17 cell differentiation both in vitro and in vivo.Ectopic expression of Jmjd3 largely rescued the impaired differentiation of Th17 cells in vitro in Jmjd3-deficientCD41 T cells.Importantly,Jmjd3-deficient mice were resistant to the induction of experimental autoimmune encephalomyelitis(EAE).Furthermore,inhibition of the H3K27 demethylase activity with the specific inhibitor GSK-J4 dramatically suppressed Th17 cell differentiation in vitro.At the molecular level,Jmjd3 directly bound to and reduced the level of H3K27 trimethylation(me3)at the genomic sites ofRorc,which encodes the masterTh17 transcription factorRorgt,and Th17 cytokine genes such as Il17,Il17f,and Il22.Therefore,our studies established acritical role of Jmjd3-mediatedH3K27demethylation inTh17 cell differentiation andsuggest that Jmjd3 can be a novel therapeutic target for suppressing autoimmune responses.

Glutamine metabolism in Th17/Treg cell fate:applications in Th17 cell-associated diseases

Alteration in the Th17/Treg cell balance is implicated in various autoimmune diseases and these disease-associated pathologies.Increasing investigations have shown that glutamine metabolism regulates the differentiation of Th17 and Treg cells.Here we summarize the mechanisms by which glutamine metabolism regulates Th17/Treg cell fate.Some examples of a glutamine metabolism-dependent modulation of the development and progression of several Th17/Treg cell-associated diseases are provided afterward.This review will provide a comprehensive understanding of the importance of glutamine metabolism in the fate of Th17/Treg cell differentiation.

Proteasome inhibition suppresses Th17 cell generation and ameliorates autoimmune development in experimental Sjögren’s syndrome

Immunoproteasome activation in immune cells is involved in the modulation of immune responses.Increasing evidence indicates that proteasome inhibitors show beneficial effects in treating autoimmune diseases,but it remains unclear whether proteasome inhibition is an effective approach for suppressing autoimmune development in Sjögren’s syndrome(SS).Our previous work has demonstrated a critical role for Th17 cells in the development of experimental SS(ESS)in mice.In this study,we detected high levels of low-molecular-weight protein 7(LMP7),a key subunit of the immunoproteasome,in Th17 cells from ESS mice.Moreover,treatment with bortezomib(BTZ),a proteasome inhibitor,markedly suppressed Th17 differentiation in both murine and human naive T cells in culture.Furthermore,ESS mice treated with BTZ displayed significantly higher saliva flow rates and a reduction in tissue destruction in the salivary glands compared with vehicle-treated ESS mice.Notably,BTZ-treated ESS mice showed markedly decreased Th17 cells,germinal center B cells and plasma cells in the peripheral lymphoid organs.In addition,adoptively transferred wild type naive CD4+T cells rapidly differentiated into Th17 cells and induced salivary dysfunction in IL-17-deficient mice immunized for ESS induction.However,BTZ treatment profoundly suppressed the donor T-cell-derived Th17 response and ameliorated the reduction in salivary secretion in IL-17-deficient recipient mice.Taken together,our findings demonstrate that proteasome inhibition can effectively ameliorate ESS by suppressing the Th17 response,which may contribute to the development of a novel therapeutic strategy for the treatment of SS.

Aging weakens Th17 cell pathogenicity and ameliorates experimental autoimmune uveitis in mice

Aging-induced changes in the immune system are associated with a higher incidence of infection and vaccination failure.Lymph nodes,which filter the lymph to identify and fight infections,play a central role in this process.However,careful characterization of the impact of aging on lymph nodes and associated autoimmune diseases is lacking.We combined single-cell RNA sequencing(scRNA-seq)with flow cytometry to delineate the immune cell atlas of cervical draining lymph nodes(CDLNs)of both young and old mice with or without experimental autoimmune uveitis(EAU).We found extensive and complicated changes in the cellular constituents of CDLNs during aging.When confronted with autoimmune challenges,old mice developed milder EAU compared to young mice.Within this EAU process,we highlighted that the pathogenicity of T helper 17 cells(Th17)was dampened,as shown by reduced GM-CSF secretion in old mice.The mitigated secretion of GMCSF contributed to alleviation of IL-23 secretion by antigen-presenting cells(APCs)and may,in turn,weaken APCs’effects on facilitating the pathogenicity of Th17 cells.Meanwhile,our study further unveiled that aging downregulated GM-CSF secretion through reducing both the transcript and protein levels of IL-23R in Th17 cells from CDLNs.Overall,aging altered immune cell responses,especially through toning down Th17 cells,counteracting EAU challenge in old mice.

Increase of peripheral Th17 lymphocytes during acute cellular rejection in liver transplant recipients

BACKGROUND: Although many human inflammatory and autoimmune diseases were previously considered to be mediated by T helper type 1 (Th1) cells, the recently described Th17 cells play dominant roles in several of these diseases. We and others speculated that allograft rejection after organ transplantation may also involve Th17 cells. Episodes of acute rejection occur in 30% of liver transplants. This study aimed to determine the frequency of circulating Th17 cells in patients who had received liver transplants for benign end-stage liver disease and to identify any association between acute rejection episodes and levels of Th17 cells in the peripheral blood. METHODS: A prospective study compared Th17 cells from 76 consecutive benign end-stage liver disease patients who had undergone orthotopic liver transplantation from 2007 to 2011 with those from 20 age-matched healthy individuals. Peripheral blood samples were collected at different time points within one year after transplant. Blood samples and liver biopsies were also collected at the diagnosis of acute rejection. Percentages of circulating CD4+ IL-17+ cells were measured by flow cytometry The transplant patients were classified into two groups: a rejection group consisting of 17 patients who had an episode of acute rejection, and a non-rejection group comprising the remaining 59 patients with no acute rejection episodes Percentages of circulating Th17 cells were compared between the two groups and controls. RESULTS: The levels of circulating CD4+ IL-17+ T cells in the rejection group were higher during acute rejection than those in the non-rejection group (2.56±0.43% versus 1.79±0.44% P<0.001). The frequency of CD4+ IL-17+ cells in peripheral blood was positively correlated with the rejection activity index (r=0.79, P=0.0002).CONCLUSION: Circulating Th17 cells may be useful as a surrogate marker for predicting acute rejection in liver transplant recipients.

芍药苷对慢性支气管炎模型大鼠Th17及Treg细胞亚群的影响

目的:探究芍药苷对慢性支气管炎(CB)大鼠Th17、Treg细胞亚群、肺功能的影响以及药理作用。方法:将SD大鼠采用复合诱导法建立CB模型,随机分成CB组(生理盐水)、低剂量芍药苷组(50 mg/kg)、中剂量芍药苷组(100 mg/kg)、高剂量芍药苷组(200 mg/kg)和核酪组(阳性对照,核酪口服液),10只;另设对照组(生理盐水)10只,造模后按照分组灌胃2 ml/100 g相应药物。给药完成后,观察大鼠一般情况并进行肺功能及血气分析;HE染色观察肺组织形态;流式细胞仪检测大鼠肺组织CD4^(+)T、CD8^(+)T、Th17(CD4^(+)IL-17^(+)T)、Treg(CD4^(+)CD25^(+)FOXP3^(+)T)细胞;ELISA法检测肺组织中IL-10、IL-22、IL-17水平。结果:CB组大鼠活动迟缓,毛色暗淡,身体卷缩,伴咳嗽、鼻腔潮湿,肺组织可见淋巴细胞浸润、支气管壁变形、黏膜阻塞等病变;芍药苷各组及核酪组上述症状及损伤不同程度缓解,高剂量组最轻。与对照组比较,CB组气道阻力、动脉血二氧化碳分压(Pa‐CO_(2))、IL-17、IL-22水平及CD4^(+)T、CD8^(+)T、Th17细胞、Th17/Treg、CD4^(+)T/CD8^(+)T均升高,动脉血氧分压(PaO_(2))、IL-10水平及Treg细胞均降低(P均<0.05);与CB组比较,低、中、高剂量芍药苷组气道阻力、PaCO_(2)、IL-17、IL-22水平及CD4^(+)T、CD8^(+)T、Th17细胞、Th17/Treg、CD4^(+)T/CD8^(+)T水平依次降低,PaO_(2)、IL-10水平及Treg细胞依次升高(P均<0.05);中剂量芍药苷组气道阻力等以上指标与核酪组相比差异无统计学意义(P均>0.05)。结论:芍药苷可调节T淋巴细胞活化,减少Th17细胞分化,增加Treg细胞分化,减轻CB大鼠炎症水平及肺损伤。