Key molecules in the differentiation and commitment program of T helper 17 (Th17) cells up-to-date

Cytokine network imbalance in children with B-cell acute lymphoblastic leukemia at diagnosis

Immune imbalance has been proved to be involved in the pathogenesis of hematologic neoplasm. However, little research has been reported altered cytokine network in childhood B-cell acute lymphoblastic leukemia (B-ALL) at diagnosis. Our study aimed to evaluate the cytokine network in peripheral blood of newly diagnosed pediatric patients with B-ALL. Serum levels of interleukin (IL)-2, IL-4, IL-6, IL-10, tumor necrosis factor (TNF), interferon (IFN)-γ, and IL-17A in 45 children with B-ALL and 37 healthy control children were measured by cytometric bead array, while the level of transforming growth factor-β1 (TGF-β1) in the serum was measured by enzyme-linked immunosorbent assay. Patients showed a significant increase in IL-6 (p < 0.001), IL-10 (p < 0.001), IFN-γ (p = 0.023) and a significant reduction in TGF-β1 (p = 0.001). The levels of IL-2, IL-4, TNF and IL-17A were similar in the two groups. Higher concentrations of pro-inflammatory cytokines were associated with febrile in patients without apparent infection by using unsupervised machine learning algorithms. In conclusion, our results indicated a critical role for aberrant cytokine expression profiles in the progression of childhood B-ALL. Distinct cytokine subgroups with different clinical features and immune response have been identified in patients with B-ALL at the time of diagnosis.

No Significant Effects of IL-23 on Initiating and Perpetuating the Axial Spondyloarthritis: The Reasons for the Failure of IL-23 Inhibitors

Axial spondyloarthritis (axSpA) is comprised of ankylosing spondylitis (AS) and non-radiographic axSpA. In recent years, the involvement of the interleukin (IL)-23/IL-17 axis in the pathophysiology of axSpA has been widely proposed. Since IL-23 is an upstream activating cytokine of IL-17, theoretically targeting IL-23 should be effective in axSpA, especially after the success of the treatment with IL-17 blockers in the disorder. Unfortunately, IL-23 blockade did not show meaningful efficacy in clinical trials of AS. In this review, we analyzed the possible causes of the failure of IL-23 blockers in AS: 1) the available data from an animal model is not able to support that IL-23 is involved in a preclinical rather than clinical phase of axSpA; 2) Th17 cells are not principal inflammatory cells in the pathogenesis of axSpA; 3) IL-17 may be produced independently of IL-23 in several immune cell types other than Th17 cells in axSpA; 4) no solid evidence supports IL-23 as a pathogenic factor to induce enthesitis and bone formation. Taken together, IL-23 is not a principal proinflammatory cytokine in the pathogenesis of axSpA.

Intestinal bacterial indicator phylotypes associate with impaired DNA double-stranded break sensors but augmented skeletal bone micro-structure

Intestinal microbiota are considered a sensor for molecular pathways, which orchestrate energy balance, immune responses, and cell regeneration. We previously reported that microbiota restriction promoted higher levels of systemic radiation-induced genotoxicity, proliferative lymphocyte activation, and apoptotic polarization of metabolic pathways. Restricted intestinal microbiota (RM) that harbors increased abundance of Lactobacillus johnsonii (LBJ) has been investigated for bacterial communities that correlated radiation-induced genotoxicity. Indicator phylotypes were more abundant in RM mice and increased in prevalence after whole body irradiation in conventional microbiota (CM) mice, while none of the same ten most abundant phylotypes were different in abundance between CM mice before and after heavy ion irradiation. Muribaculum intestinale was detected highest in female small intestines in RM mice, which were lacking Ureaplasma felinum compared with males, and thus these bacteria could be contributing to the differential amounts of radiation-induced systemic genotoxicity between the CM and RM groups. Helicobacter rodentium and M.intestinale were found in colons in the radiation-resistant CM phenotype. While the expression of interferon-γ was elevated in the small intestine, and lower in blood in CM mice, high-linear energy transfer radiation reduced transforming growth factor-β with peripheral interleukin (IL)-17 in RM mice, particularly in females. We found that female RM mice showed improved micro-architectural bone structure and anti-inflammatory radiation response compared with CM mice at a delayed phase 6 weeks postexposure to particle radiation. However, microbiota restriction reduced inflammatory markers of tumor necrosis factor in marrow, when IL-17 was reduced by intraperitoneal injection of IL-17 neutralizing antibody.

Analysis of the roles of dietary protein and calcium in fluoride-induced changes in T-lymphocyte subsets in rat

The roles of dietary protein (Pr) and calcium (Ca) levels on the changes in T-lymphocyte subsets induced by excessive fluoride (F) intake were assessed using rats that were malnourished for 120 days as a model. The CD⁴⁺ and CD⁸⁺ T-lymphocytes in the spleen tissue were determined by flow cytometry and immunofluorescence assay. The percentages of CD³⁺ , CD⁴⁺ , and CD⁸⁺ T-lymphocytes were reduced in the spleen of rats exposed to excessive F, and malnutrition aggravated these changes in the T-lymphocytes. In addition, the mRNA expression levels of IL-1β, IL-2, IL-6, TNF-α, and IFN-γ in the spleen were downregulated significantly. We also reported herein the increased apoptosis ratio following caspase-9 and caspase-3 upregulation in the spleen of rats exposed to excessive amount of F. Light and transmisison electron microscopy revealed the irregularly arranged lymphocytes, few lymph nodules and the apoptotic characteristic of lymphocytes, which are caused by the increased expression of caspase. In addition, Pr and Ca supplementation reversed the morphologic and T-lymphocytic changes in spleen under malnutrition. Taken together, our results revealed an endogenous caspase-mediated mechanism of regulating the apoptosis of the T-lymphocyte subsets, as well as the immune-related cytokine secretion, which reduces the immune function in F-induced rats. © 2016 Wiley Periodicals, Inc. Environ Toxicol 32: 1587-1595, 2017.

The role of Th17 and Treg responses in the pathogenesis of RSV infection

The respiratory syncytial virus (RSV) represents the leading cause of viral bronchiolitis and pneumonia in children worldwide and is associated with high morbidity, hospitalization rate, and significant mortality rates. The immune response elicited by RSV is one of the main factors contributing to the pathogenesis of the disease. Two subsets of the cellular immune response, the T helper 17 cell (Th17) and the regulatory T-cell (Treg), and more particularly the balance between these two subsets, might play a significant role in the pathogenesis of the RSV infection. The developmental pathways of Th17 and Treg cells are closely and reciprocally interconnected and plasticity has been demonstrated from Treg toward Th17. During an RSV infection, the functions of both subsets are opposed to one another regarding viral clearance and clinical severity. Th17 and Treg cells offer a promising new view on the pathogenesis of an RSV infection and deserve further exploration.

Optimal clearance of Sporothrix schenckii requires an intact Th17 response in a mouse model of systemic infection

The discovery of Th17 cells, along with many other Th cell subsets in the recent years, has expanded the Th1/Th2 paradigm that had persisted since its proposition by Mosmann in 1986. Defined by the characteristic expression of the transcription factor retinoic-related orphan receptor γt (RORγt) and production of IL-17A (IL-17), Th17 cells are powerful inducers of tissue inflammation with a recognized role against extracellular bacteria and fungi. Despite this, the interest in their study came from the pivotal role they play in the development and maintenance of major chronic inflammatory conditions such as multiple sclerosis, rheumatoid arthritis and Crohn's disease, hence they have been the target of promising new anti-Th17 therapies. Accordingly, the identification of opportunistic pathogens whose clearance relies on the Th17 response is of huge prophylactic importance. As shown here for the first time, this applies to Sporothrix schenckii, a thermo-dimorphic fungus and the causative agent of sporotrichosis. Our results show that both Th17 and Th1/Th17 mixed cells are developed during the S. schenckii systemic mice infection, which also leads to augmented production of IL-17 and IL-22. Also, by using an antibody-mediated IL-23 depletion model, we further demonstrate that optimal fungal clearance, but not survival, depends on an intact Th17 response.

Bu-Shen-Yi-Qi formulae suppress chronic airway inflammation and regulate Th17/Treg imbalance in the murine ovalbumin asthma model

ETHNOPHARMACOLOGICAL RELEVANCE

Bu-Shen-Yi-Qi formulae (BSYQF) are frequently used in the treatment of chronic inflammatory diseases in the respiratory system in traditional Chinese medicine (TCM). However, the regulatory effect of BSYQF on T helper 17 (Th17) and regulatory T (Treg) cells in murine ovalbumin (OVA) asthma model remains poorly understood. In the present study, we sought to determine the effect of high-performance liquid chromatography/mass spectrometry (HPLC/MS) standardized BSYQF on chronic airway inflammation and Th17/Treg imbalance in the murine OVA asthma model.

MATERIALS AND METHODS

The murine asthma model was induced by OVA sensitization and challenge and BSYQF was oral administrated. 24h after last OVA exposure, airway hyperresponsiveness (AHR) to methacholine (Mch) was assessed, and inflammatory cell counts and classification in bronchoalveolar lavage fluid (BALF) were analysed. Histopathological evaluation of the lung tissue was performed by hematoxylin and eosin (H&E) and periodic acid-Schiff (PAS) staining. Th17 and Treg associated cytokine levels in serum and BALF as well as transcription factors expression in the lung tissue were measured by ELISA, Bio-Plex and western blot assay. We also analysed the CD4(+)RORγt(+) and CD4(+)Foxp3(+) T cells in BALF and spleen by flow cytometric analysis.

RESULTS

Our results demonstrated that oral administration of BSYQF inhibited the markedly increased AHR and lung inflammation (p<0.05), resulted in a dramatic reduction in total inflammatory cells as well as neutrophils (Neu), lymphocytes (Lym), monocytes (Mon), eosinophils (Eos) and basophils (Bas) of OVA-induced asthmatic mice (p<0.05). Furthermore, BSYQF treatment caused a distinct reduction in IL-6, IL-10 and IL-17A levels in serum (p<0.05), and induced a significant improvement in IL-6 and IL-10 as well as a marked decrease in TGF-β1 and IL-17A levels in BALF of OVA-induced asthmatic mice (p<0.05). Mice in BSYQF treated groups also had decreased RORγt and increased Foxp3 expression in the lung tissue (p<0.05). Flow cytometry analysis revealed that CD4(+)RORγt(+) T cells elevated markedly and CD4(+)Foxp3(+) T cells decreased prominently in BALF and spleen in murine OVA asthma model (p<0.05), and BSYQF and DEX treatment lead to an obvious reduction in CD4(+)RORγt(+) T cells in BALF (p<0.05) but not in spleen. BSYQF and DEX treatment resulted in an obvious elevation in CD4(+)Foxp3(+) T cells in BALF and spleen (p<0.05).

CONCLUSIONS

Collectively, these results demonstrated that BSYQF could suppress chronic airway inflammation and regulate Th17/Treg imbalance by inhibition of Th17 and enhancement of Treg functions in the murine OVA asthma model, which may help to elucidate the underlying regulatory mode of BSYQF on asthma treatment.

Th17 differentiation and their pro-inflammation function

CD4(+) T helper cells are classical but constantly reinterpreted T-cell subset, playing critical roles in a diverse range of inflammatory responses or diseases. Depending on the cytokines they release and the immune responses they mediate, CD4(+) T cells are classically divided into two major cell populations: Th1 and Th2 cells. However, recent studies challenged this Th1/Th2 paradigm by discovering several T-helper cell subsets with specific differentiation program and functions, including Th17 cells, Treg cells, and Tfh cells. In this chapter, we summarize the current understanding and recent progresses on the Th17 lineage differentiation and its effector impacts on variety of inflammatory responses or disease pathogenesis.

Regulation of Th17/Treg function contributes to the attenuation of chronic airway inflammation by icariin in ovalbumin-induced murine asthma model

Icariin which is a flavonoid glucoside isolated from Epimedium brevicornu Maxim, has been reported to have anti-osteoporotic, anti-inflammatory and anti-depressant-like activities. In this study, we observed the effect of icariin on airway inflammation of ovalbumin (OVA)-induced murine asthma model and the associated regulatory mode on T-helper (Th)17 and regulatory T (Treg) cell function. Our data revealed that chronic OVA inhalation induced a dramatic increase in airway resistance (RL) and decrease in the lung dynamic compliance (Cdyn), and icariin and DEX treatment caused significant attenuation of such airway hyperresponsiveness (AHR). BALF cell counts demonstrated that icariin and DEX led to a prominent reduction in total leukocyte as well as lymphocyte, eosinophil, neutrophil, basophil and monocyte counts. Histological analysis results indicated that icariin and DEX alleviated the inflammatory cells infiltrating into the peribronchial tissues and goblet cells hyperplasia and mucus hyper-production. Flow cytometry test demonstrated that icariin or DEX administration resulted in a significant percentage reduction in CD4+RORγt+ T cells and elevation of CD4+Foxp3+ T cells in BALF. Furthermore, icariin or DEX caused a significant reduction in IL-6, IL-17 and TGF-β level in BALF. Unfortunately, icariin had no effect on IL-10 level in BALF. Western blot assay found that icariin or DEX suppressed RORγt and promoted Foxp3 expression in the lung tissue. qPCR analysis revealed that icariin and DEX resulted in a notable decrease in RORγt and increase in Foxp3 mRNA expression in isolated spleen CD4+ T cell. In conclusion, our results suggested that icariin was effective in the attenuation of AHR and chronic airway inflammatory changes in OVA-induced murine asthma model, and this effect was associated with regulation of Th17/Treg responses, which indicated that icariin may be used as a potential therapeutic method to treat asthma with Th17/Treg imbalance phenotype.

Human umbilical cord mesenchymal stem cells protect against ischemic brain injury in mouse by regulating peripheral immunoinflammation

Current treatments for ischemic stroke are limited, stem cell transplantation offers great potential as a therapeutic strategy. The present study was undertaken to determine whether human umbilical cord-derived mesenchymal stem cells (hUC-MSCs) could improve brain injury after middle cerebral artery occlusion (MCAO) through modulating peripheral immunoinflammation. The study showed that neurological deficit was ameliorated and brain edema, infarct volume was significantly decreased from 72 h to 1 week post-MCAO with hUC-MSCs treatment via tail vein injection within 30 mins after stroke; hUC-MSCs attenuated the levels of inflammatory factors including IL-1, TNF-α, IL-23, IL-17 and IL-10 in peripheral blood serum and ischemia hemisphere after stroke; hUC-MSCs significantly decreased the level of Th17 cells at 24h and increased the level of Tregs at 72 h post-MCAO in peripheral immune system; the level of TGF-β in blood serum was enhanced by hUC-MSCs. In conclusion, our findings suggested that hUC-MSCs had neuroprotection in MCAO mice by TGF-β modulating peripheral immune and hUC-MSCs may be as a potential therapy for ischemic stroke.

IL-35 promotes pancreas cancer growth through enhancement of proliferation and inhibition of apoptosis: evidence for a role as an autocrine growth factor

Interleukin-35 (IL-35), an IL-12 cytokine family member, mediates the immune inhibitory function of regulatory T cells (Treg). We assayed the presence of IL-35 in paraffin-embedded human pancreas cancer (PCAN) and unexpectedly found IL-35 was expressed mainly by epithelial derived PCAN cells, but not by Treg. We further examined the expression and effect of exogenous IL-35 in human PCAN cell lines and found IL-35 promoted growth and inhibited apoptosis in PCAN cell lines. IL-35 induced proliferation correlated with an increase in cyclin B, cyclin D, cdk2, and cdk4 and a decrease in p27 expression, while inhibition of apoptosis was associated with an increase in Bcl-2 and a decrease in TRAILR1. We conclude IL-35 is produced by PCAN in vivo and promotes PCAN cell line growth in vitro. These results might indicate an important new role for IL-35 as an autocrine growth factor in PCAN growth.

Changes in circulating Foxp3+ regulatory T cells and interleukin-17-producing T helper cells during HBV-related acute-on-chronic liver failure

AIM: To longitudinally investigate cytokine gene expression and protein levels in Th17 and Treg cells, to observe T-cell phenotypes during hepatitis B virus (HBV)-related acute-on-chronic liver failure (ACHBLF) and to analyze changes in Th17 and Treg phenotypes during disease progression.

METHODS: We measured the expression of seven Th17/Treg differentiation-related genes and serum concentrations of the corresponding cytokines in 18 ACHBLF, 18 chronic hepatitis B (CHB) disease controls and 10 healthy controls (HCs) by real-time quantitative PCR and enzyme linked immunosorbent assay. Peripheral Th17 and Treg cell frequencies were analyzed by flow cytometry.

RESULTS: From the onset of ACHBLF, patients presented with a conductive Th17 differentiation cytokine environment accompanied by high Th17 frequency and high serum IL-17 levels, which were sustained throughout the disease course. The Treg-related cytokine IL-2 and Foxp3 were also up-regulated from disease onset, and Foxp3 gene expression showed a gradually increasing trend during ACHBLF. The circular phenotype of Treg and Th17 cells showed changes from the onset of ACHGLF. At disease onset, Th17 frequency increased significantly compared with both CHB and HCs, but Treg cell frequency decreased significantly compared with CHB. During the ACHBLF event, Th17 frequency remained higher compared with HCs, but decreased sharply from the peak point to the recovery point; Treg cell frequency increased gradually during the ACHBLF event. Treg and Th17 cell counts correlated with ACHBLF development; in all patients, serum IL-17 levels significantly correlated with patient serum ALT levels. In survivors, Th17 frequency at the onset point and the Treg to Th17 ratio at the peak point correlated with the patient’s model for end stage liver disease (MELD) plus sodium (MELD-Na) score. The Treg to Th17 ratio and the Th17 frequency at onset were significant predictors of patient survival. Low Treg/Th17 cell ratios at the onset predicted poor survival. Survivors exhibited an initial decrease in the circulating Treg/Th17 ratio from the onset to the peak time, and subsequently displayed a continuous increase.

CONCLUSION: Treg and Th17 cells showed changes in genes, protein levels and T cell phenotypes during ACHBLF events. An increased Treg/Th17 ratio was associated with the survival of ACHBLF patients.

Detection of dynamic frequencies of Th17 cells and their associations with clinical parameters in patients with systemic lupus erythematosus receiving standard therapy

Recent evidence implicated an important role of Th17 cells in the pathogenesis of systemic lupus erythematosus (SLE). However, the association between dynamic changes of Th17 cell frequency and clinical parameters in SLE patients receiving clinical managements remains unknown. Here, we sought to evaluate their correlation in Chinese new-onset SLE patients with standard therapy. We found that the frequency of Th17 cells was higher in SLE patients than that in healthy controls and could be decreased by standard care. In consistent, the level of serum IL-6, IL-1β, IL-23, and Stat3 activity was elevated in SLE patients and down-regulated by disease treatment. Of note, the frequency of Th17 cells was correlated with SLEDAI and serum C3 in SLE patients. The changes of Th17 cell frequency were associated with those of SLEDAI and serum C3 in SLE patients between pretreatment and posttreatment. Further, the Th17 cell frequency was positively correlated with serum anti-dsDNA antibody in SLE patients. The changes of Th17 cell frequency were associated with those of serum anti-dsDNA antibody in SLE patients. Our findings showed that dynamic frequencies of Th17 cells were closely correlated with clinical parameters in SLE patients receiving standard treatment, which could facilitate the efficient management and development of novel therapeutics for SLE.

The role of T helper (TH)17 cells as a double-edged sword in the interplay of infection and autoimmunity with a focus on xenobiotic-induced immunomodulation

Extensive research in recent years suggests that exposure to xenobiotic stimuli plays a critical role in autoimmunity induction and severity and that the resulting response would be exacerbated in individuals with an infection-aroused immune system. In this context, heavy metals constitute a prominent category of xenobiotic substances, known to alter divergent immune cell responses in accidentally and occupationally exposed individuals, thereby increasing the susceptibility to autoimmunity and cancer, especially when accompanied by inflammation-triggered persistent sensitization. This perception is learned from experimental models of infection and epidemiologic studies and clearly underscores the interplay of exposure to such immunomodulatory elements with pre- or postexposure infectious events. Further, the T_H17 cell subset, known to be associated with a growing list of autoimmune manifestations, may be the “superstar” at the interface of xenobiotic exposure and autoimmunity. In this review, the most recently established links to this nomination are short-listed to create a framework to better understand new insights into T_H17's contributions to autoimmunity.

Anti-cancer versus cancer-promoting effects of the interleukin-17-producing T helper cells

Research on T helper 17 (Th17) cells with regard to immunoediting has revealed elusive results. Whereas enhanced Th17 response and related molecules such as interleukin (IL)-17, IL-21, IL-22, IL-23 and STAT3 accompanied tumor induction and progression, finding that tumor growth/stage was negatively correlated with increased infiltration of Th17 cells in the tumor mass has prompted elucidation of various antitumor mechanisms elicited by Th17 and their related molecules. The pro-tumor efficacy of Th17 response included promotion of neutrophilia and induction of angiogenic (e.g. VEGF, MMP2 and MMP9) and anti-apoptotic factors (e.g. Bcl-XL), as well as expansion and activation of myeloid-derived suppressor cells, which facilitate generation of tumor-specific regulatory T cells. Other tumor immunogenic settings revealed anti-tumor pathways including induction of cytotoxic activity, expression of MHC antigens, the ability Th17 cells to reside within the tumor, and to convert into IFN-γ producers. Notably, Th17 cell related molecules exert indirect pro- or anti-tumor effects via inducing viral persistence or mediating protective mechanisms against bacterial and viral infection. Herein, the recent literature revealing such immunoediting events mediated by Th17 cells and their associated molecules as delivered by various experimental regimens and observed in cancer patient are revised, with a focus on some proposed anti-cancer therapies.