Sirolimus ameliorates inflammatory responses by switching the regulatory T/T helper type 17 profile in murine colitis

Inflammatory bowel disease is characterized by dysregulated immune responses in inflamed intestine, with dominance of interleukin‐17 (IL‐17) ‐producing cells and deficiency of regulatory T (Treg) cells. The aim of this study was to investigate the effect and mechanisms of sirolimus, an inhibitor of the mammalian target of rapamycin, on immune responses in a murine model of Crohn's disease. Murine colitis was induced by intrarectal administration of 2,4,6‐trinitrobenzene sulphonic acid at day 0. Mice were then treated intraperitoneally with sirolimus daily for 3 days. The gross and histological appearances of the colon and the numbers, phenotype and cytokine production of lymphocytes were compared with these characteristics in a control group. Sirolimus treatment significantly decreased all macroscopic, microscopic and histopathological parameters of colitis that were analysed. The therapeutic effects of sirolimus were associated with a down‐regulation of pro‐inflammatory cytokines tumour necrosis factor‐α, IL‐6 and IL‐17A. Intriguingly, sirolimus administration resulted in a prominent up‐regulation of the regulatory cytokine transforming growth factor‐β. Supporting the hypothesis that sirolimus directly affects the functional activity of CD4⁺ CD25⁺ Treg cells, we observed a remarkable enhancement of FoxP3 expression in colon tissues and isolated CD4⁺ T cells of sirolimus‐treated mice. Simultaneously, sirolimus treatment led to a significant reduction in the number of CD4⁺ IL‐17A⁺ T cells in the mesenteric lymph node cells as well as IL‐17A production in mesenteric lymph node cells. Therefore, sirolimus may offer a promising new therapeutic strategy for the treatment of inflammatory bowel disease.     

腹腔镜和开腹手术治疗化脓性阑尾炎的对比研究

目的探讨腹腔镜阑尾切除术治疗化脓性阑尾炎的临床应用价值。方法回顾分析113例化脓性阑尾炎的手术治疗病例,其中行腹腔镜阑尾切除术61例（LA组）,行开腹阑尾切除术52例（OA组）。比较两组的手术时间、术中出血量、术后肛门排气时间、术后疼痛程度、术后住院时间、切口感染率和住院费用。结果 LA组中有4例中转开腹。LA组的住院费用和术中出血量高于OA组（P〈0.05）,术后疼痛程度和切口感染率较OA组低（P〈0.05）。两组患者在手术时间、术后住院时间和术后肛门排气时间的差异无统计学意义（P〉0.05）。结论腹腔镜和开腹手术治疗化脓性阑尾炎各有优势,临床工作中应根据患者具体病情和医师的手术经验合理选用。     

Loss of balance between T helper type 17 and regulatory T cells in chronic human immunodeficiency virus infection

The aim of this study is to characterize the changes of CD4(+) CD25(high) forkhead box P3 (FoxP3(+) ) regulatory T cells (T(reg) ), interleukin (IL)-17 secreting T helper type 17 (Th17) cell frequencies and the balance of these two subsets in a cohort of chronic human immunodeficiency virus type 1 (HIV-1)-infected patients in China. A total of 115 untreated chronic HIV-infected individuals and 32 healthy donors were recruited in this study. Peripheral blood mononuclear cells were isolated from ethylenediamine tetracetic acid (EDTA) anti-coagulated fresh whole blood and stained to characterize the frequencies of T(reg) and Th17. Of a total 115 patients, 42 individuals including 10 elite controllers were followed-up for more than 1 year, and changes of T(reg) and Th17 frequencies were analysed over time. The continuous loss of Th17 cells was accompanied by a concomitant rise in the frequency of T(reg) cells, resulting in a loss of Th17/T(reg) balance during the progressive HIV infection. Meanwhile, the T(reg) levels, Th17 levels and Th17/T(reg) ratios of the elite controller group were comparable to those of the HIV-1 negative controls in the follow-up study. Additionally, we demonstrated that loss of balance between Th17 and T(reg) is associated with an earlier CD4 T cell decline during the course of HIV infection. Our results indicate that a loss of immune-balance of Th17 to T(reg) during HIV-1 disease progression and the persistence of such an immune-balance in the elite controllers may have a critical role in HIV-1 infection and further shed new light into understanding the pathogenesis of HIV-1.     

Regulatory T cells and T helper 17 cells in viral infection

CD4⁺ T cells are the central element of the adaptive immune responses and protect the body from a variety of pathogens. Starting from naive cells, CD4⁺ T cells can differentiate into various effector cell subsets with specialized functions including T helper (Th) 1, Th2, Th17, regulatory T (Treg) and T follicular helper (Tfh) cells. Among them, Tregs and Th17 cells show a strong plasticity allowing the functional adaptation to various physiological and pathological environments during immune responses. Although they are derived from the same precursor cells and their differentiation pathways are interrelated, the terminally differentiated cells have totally opposite functions. Studies have shown that Tregs and Th17 cells have rather complex interplays in viral infection: Th17 cells may contribute to immune activation and disease progression while Tregs may inhibit this process and play a key role in the maintenance of immune homoeostasis, possibly at the cost of compromised viral control. In this review, we take respiratory syncytial virus (RSV), hepatitis B virus (HBV)/hepatitis C virus (HCV) and human immunodeficiency virus (HIV) infections as examples to discuss these interplays and their impacts on disease progression in viral infection.     

miR‐155 deficiency protects mice from experimental colitis by reducing T helper type 1/type 17 responses

Inflammatory bowel disease (IBD), a chronic intestinal inflammatory condition that affects millions of people worldwide, results in high morbidity and exorbitant health-care costs. The critical features of both innate and adaptive immunity are to control inflammation and dysfunction in this equilibrium is believed to be the reason for the development of IBD. miR-155, a microRNA, is up-regulated in various inflammatory disease states, including IBD, and is a positive regulator of T-cell responses. To date, no reports have defined a function for miR-155 with regard to cellular responses in IBD. Using an acute experimental colitis model, we found that miR-155^−/− mice, as compared to wild-type control mice, have decreased clinical scores, a reversal of colitis-associated pathogenesis, and reduced systemic and mucosal inflammatory cytokines. The increased frequency of CD4⁺ lymphocytes in the spleen and lamina propria with dextran sodium sulphate induction was decreased in miR-155^−/− mice. Similarly, miR-155 deficiency abrogated the increased numbers of interferon-γ expressing CD4⁺ T cells typically observed in wild-type mice in this model. The frequency of systemic and mucosal T helper type 17-, CCR9-expressing CD4⁺ T cells was also reduced in miR-155^−/− mice compared with control mice. These findings strongly support a role for miR-155 in facilitating pro-inflammatory cellular responses in this model of IBD. Loss of miR-155 also results in decreases in T helper type 1/type 17, CD11b^+, and CD11c⁺ cells, which correlated with reduced clinical scores and severity of disease. miR-155 may serve as a potential therapeutic target for the treatment of IBD.     

转录因子IRF8抑制Th17细胞分化并减轻T细胞免疫介导的小鼠结肠炎

 目的：转录因子干扰素调节因子（interferon regulatory factor, IRF）家族与Th17的发育密切相关,近年来发现Th17细胞在炎症性肠病的发病中发挥重要作用,本研究探讨IRF8对Th17发育及T细胞转染免疫介导的小鼠实验性肠炎的影响。方法：(1)采用流式细胞术分选野生型（WT）或IRF8全基因敲除(IRF8 -/-)小鼠脾脏和淋巴结的naive CD4 +T细胞(CD4 + CD62L +CD44 low),在Th1、Th2或Th17极化的条件下培养,采用流式细胞术检测Th1、Th2和Th17的比例。(2)建立实验性肠炎模型：采用免疫磁珠法分选WT或IRF8 -/-小鼠中的脾脏和淋巴结中CD4 +CD25 +Treg,WT小鼠的CD4 + CD45RB hi T细胞单独或者分别联合WT或IRF8 -/-小鼠的CD4 +CD25 +Treg腹腔注射给RAG1 -/-小鼠;WT或IRF8 -/-小鼠的naive CD4 + CD45RB hi T细胞腹腔注射给RAG1 -/-小鼠;观察上述小鼠每周体重的变化,第5周时处死小鼠,进行结肠炎病理评分和肠系膜淋巴结T淋巴细胞亚群检测。结果：(1)IRF8 -/-较WT的naive CD4 +T细胞在极化条件下向Th17细胞分化更明显(P<001),而对Th1和Th2细胞的分化无影响(P>0.05)。(2)CD4 + CD45RB hi T细胞转染给RAG1 -/-小鼠,IRF8 -/-较WT供体鼠引起的RAG1 -/-小鼠体重显著降低(P<0.05),结肠炎评分显著增高（P<0.05）,且肠系膜淋巴结中IL-17 +CD4 +细胞比例明显增高(P<0.01),而 IFN-γ +CD4 + 和 Foxp3 +CD4 +细胞比例无影响(P>0.05);IRF8 -/-小鼠的CD4 +CD25 +Treg对WT小鼠CD4 + CD45RB hi T细胞转染给RAG1 -/-小鼠诱发的免疫介导的结肠炎显示出正常的免疫抑制作用。结论：转录因子IRF8基因敲除促进CD4 +T细胞向Th17细胞分化,促进转染naive CD4 +T细胞诱导的实验性结肠炎的发生,IRF8基因敲除小鼠Treg细胞免疫抑制功能正常。     

Imbalance between T helper type 17 and T regulatory cells in patients with primary biliary cirrhosis: the serum cytokine profile and peripheral cell population

Primary biliary cirrhosis (PBC) is an organ‐specific autoimmune liver disease characterized by progressive loss of intrahepatic small bile ducts. Cellular immune mechanisms involving T cell reaction are thought to be involved significantly in the pathogenesis of PBC. Recent studies have independently revealed enhanced T helper type 17 (Th17) response and weakened T regulatory cell (T_reg) response in some autoimmune diseases, indicating a role of Th17/T_reg imbalance in the pathogenesis of autoimmunity. This prompted us to investigate whether the Th17/T_reg balance was broken in the peripheral blood of patients with PBC and, if it was, what cytokine circumstances might contribute to this imbalance. The expression of 11 Th17/T_reg differentiation‐related genes and serum concentrations of the corresponding cytokines in 36 patients with PBC, 28 patients with chronic hepatitis B and 28 healthy controls were measured by real‐time quantitative–polymerase chain reaction and enzyme‐linked immunosorbent assay respectively. Peripheral Th17 and T_reg cells were analysed by flow cytometry. Th17‐related cytokines were increased significantly in patients with PBC. Consistent with the cytokine profile, the Th17 cell population and retinoid‐related orphan receptor γt expression were increased markedly. In contrast, the T_reg cell population and forkhead box P3 expression were decreased dramatically in the peripheral blood of patients with PBC. Our study revealed that the Th17/T_reg imbalance, both cytokine profile and cell numbers, exists in patients with PBC, suggesting its potential role in the breakdown of immune self‐tolerance in PBC. Interleukin‐23, which characterized the imbalanced cytokine profile, may play an essential role in Th17‐related human autoimmunity.     

The role of T helper 17 and regulatory T cells in tumor microenvironment

T helper 17 (Th17) cells were first described as a novel T helper cell lineage independent from Th1 and Th2 subsets. Th17 cells play vital roles in inflammation and tumor immunity. It causes the dissipation of antitumor immunity and contribution to the survival of tumor cells, worsening tumor growth and metastasis. Tumor-infiltrating Th17 cells were seen innumerous cancers in mice and humans. There has been an association between intratumoral Th17 cell infiltration and both good and bad prognoses. Besides the protumoral roles defined for IL-17 andTh17 cells, several reports have shown that Th17 cells also drive antitumoral immunity. Various mechanisms by which Th17 cells control tumor growth are as following: recruitment of several immune cells including DCs, CD4⁺ T cells, and CD8⁺ T cells within tumors, activation of CD8⁺ T cells, and probably plasticity toward Th1 phenotype, related to IFN-γ and TNF-α production. Regulatory T cells (Tregs) have been exhibited to infiltrate human tumors and are believed to restrict antitumor immunity. The effect of Treg cells has been more controversial. Whereas some studies have proposed that a high density of Treg cells within the tumor associated with a poor clinical prognosis, other studies have presented a positive clinical prognosis, underlining the importance of elucidating the clinical significance of Treg cells further. Treg and Th17 cells play both positive and negative roles in regulating antitumor immune responses. In spite of the presence of these cells, yet some tumors develop and grow. These T cells by themselves are not adequate to efficiently mount antitumor immune responses.     

Pathogenic T helper type 17 cells contribute to type 1 diabetes independently of interleukin‐22

We have shown that pathogenic T helper type 17 (Th17) cells differentiated from naive CD4⁺ T cells of BDC2·5 T cell receptor transgenic non‐obese diabetic (NOD) mice by interleukin (IL)‐23 plus IL‐6 produce IL‐17, IL‐22 and induce type 1 diabetes (T1D). Neutralizing interferon (IFN)‐γ during the polarization process leads to a significant increase in IL‐22 production by these Th17 cells. We also isolated IL‐22‐producing Th17 cells from the pancreas of wild‐type diabetic NOD mice. IL‐27 also blocked IL‐22 production from diabetogenic Th17 cells. To determine the functional role of IL‐22 produced by pathogenic Th17 cells in T1D we neutralized IL‐22 in vivo by using anti‐IL‐22 monoclonal antibody. We found that blocking IL‐22 did not alter significantly adoptive transfer of disease by pathogenic Th17 cells. Therefore, IL‐22 is not required for T1D pathogenesis. The IL‐22Rα receptor for IL‐22 however, increased in the pancreas of NOD mice during disease progression and based upon our and other studies we suggest that IL‐22 may have a regenerative and protective role in the pancreatic islets.     

Involvement of T helper type 17 and regulatory T cell activity in tumour immunology of bladder carcinoma

T helper type 17 (Th17) and regulatory T cells (T_reg) play an important role in the pathogenesis of inflammation and autoimmune disorders. Recent studies have suggested that they also had an impact on tumour immunology. However, the relationship between Th17 and T_reg cells in the pathogenesis of bladder carcinoma is still unclear. Flow cytometry was used to analyse the numbers, phenotype and cytokine production of Th17 cells in peripheral blood and tumour tissue from bladder carcinoma patients, in parallel with analysis of T_reg cells. The suppressor capacity of T_reg and the potential effects of interleukin (IL)‐2 on the differentiation of Th17 and T_reg cells in vitro were studied in a T cell stimulation and suppression assays. The results were as follows: Th17 cells were enriched in the tumours of patients with bladder carcinoma compared with the peripheral blood of patients and controls; patients with bladder carcinoma had a higher proportion of T_reg cells in peripheral blood compared with healthy controls and nearly all patients examined showed a relative enrichment of tumour‐infiltrating T_reg with respect to peripheral blood; there appeared to be an inverse relationship between tumour‐infiltrating Th17 and T_reg cells; IL‐2 could convert tumour‐infiltrating T_reg cells cultured in the presence of the autologous irradiated CD3^– fraction into Th17 cells, down‐regulate forkhead box P2 expression and suppressive capacity of T_reg cells. This study is the first to define the frequency and characteristics of Th17 cells in bladder carcinoma. We suggest that the balance between Th17 and T_reg cells may be involved in the development or progression of bladder carcinoma.     

Translational Mini-Review Series on Th17 Cells: Are T helper 17 cells really pathogenic in autoimmunity?

OTHER ARTICLES PUBLISHED IN THIS MINI‐REVIEW SERIES ON Th17 CELLS
Function and regulation of human T helper 17 cells in health and disease. Clin Exp Immunol 2009; doi:10.1111/j.1365‐2249.2009.04037.x
Induction of interleukin‐17 production by regulatory T cells. Clin Exp Immunol 2009; doi:10.1111/j.1365‐2249.2009.04038.x
CD4⁺ T helper cells: functional plasticity and differential sensitivity to regulatory T cell‐mediated regulation. Clin Exp Immunol 2009; doi:10.1111/j.1365‐2249.2009.04040.x
Development of mouse and human T helper 17 cells. Clin Exp Immunol 2009; doi:10.1111/j.1365‐2249.2009.04041.x

Summary

In this review the authors discuss the evidence for T helper type 17 (Th17) cells as pathogenic T cells in autoimmunity. Studies with cytokine‐deficient mice or blocking of interleukin (IL)‐17, IL‐21 and IL‐22 have resulted in a conflicting data set. Although in the experimental autoimmune encephalomyelitis model the role of Th17 cells remains a point of debate, this IL‐17‐producing T cell in experimental arthritis is clearly contributing to inflammation and destruction.     

T cell‐derived leptin contributes to increased frequency of T helper type 17 cells in female patients with Hashimoto's thyroiditis

Leptin modulates T cell function and plays an important role in autoimmune diseases. Our study aimed to explore the role of leptin and T helper type 17 (Th17) cells in Hashimoto's thyroiditis patients. Twenty‐seven patients with Hashimoto's thyroiditis (HT) and 20 healthy controls were enrolled into the current study. A modest increase of plasma leptin in HT patients and the CD4⁺ T cell‐derived leptin from HT patients was stronger than that from healthy controls. In HT patients, there are no statistically significant correlations between plasma leptin concentrations and the percentage of Th17 cells or the level of retinoic acid‐related orphan receptor γt (RORγt), but strong positive correlations were observed between CD4⁺ T cell‐derived leptin and the percentage of Th17 cells or the level of RORγt mRNA, and additionally significantly up‐regulated leptin, interleukin (IL)17 and RORγt mRNA levels in the thyroid tissue. Furthermore, neutralization of leptin decreases the frequency of Th17 cells in vitro. Current study has revealed an increased leptin involvment in Hashimoto's thyroiditis associated with an increased number of Th17 cells.     

Interleukin-33 alleviates psoriatic inflammation by suppressing the T helper type 17 immune response

Psoriasis is a chronic inflammatory skin disease with unclear pathogenesis. Interleukin-33 (IL-33) is highly expressed in patients with psoriasis, but its role in psoriasis is unknown. The aim of this study was to investigate the possible role of IL-33 in the pathogenesis and treatment of psoriasis. IL-33 expression was determined using enzyme-linked immunosorbent assay, real-time fluorescent quantitative polymerase chain reaction and immunohistochemical staining. CD4⁺ T cells were sorted using magnetic beads and treated with or without IL-33. Imiquimod (IMQ) was used to induce psoriatic inflammation in mice. The frequency of immune cells was determined using flow cytometry. The cytokine level in mouse skin was measured using cytometric bead array. Our results showed that IL-33 was highly expressed in the lesional skin and serum of patients with moderate-to-severe plaque psoriasis. IL-33 inhibited the expression of IL-17 in CD4⁺ T cells of psoriasis patients. Subcutaneous injection of IL-33 alleviated the IMQ-induced psoriatic inflammation in mice, reduced tumor necrosis factor-α and IL-23 expression, and decreased the proportion of T helper type 17 (Th17) cells in the skin-draining lymph nodes in the mice. Our results suggest that IL-33 plays a protective role in the pathogenesis of psoriasis by suppressing Th17 cell differentiation and function. The potential therapeutic effect of IL-33 in treating psoriasis warrants further investigation.