IL-17的信号传导及功能研究

白介素17(IL-17),辅助性T细胞T_H17分泌的特征性细胞因子,在抵抗胞外细菌、真菌感染的宿主防御以及各种自身免疫性疾病发病中起到了重要的作用。本文对T_B17细胞、IL-17的发现作了历史性回顾,并综述了IL-17受体介导的信号传导途径和生理功能的研究进展,为T_H17细胞、IL-17及其受体作为药物治疗的新靶点提供新思路。     

IL-17家族与哮喘

支气管哮喘(bronchial asthma,简称哮喘)是一种常见的慢性气道炎症性疾病,急性发作可危及生命。研究表明,细胞因子白介素17(interleukin-17,IL-17)家族成员在哮喘的发病过程中发挥着重要的作用,其中IL-17A、IL-17F和IL-17E与哮喘密切相关,是目前的研究热点。现对IL-17家族不同成员与哮喘发病机制的相关研究进展作一综述。     

人白介素6受体结合功能域的构效关系研究

以分子对接（docking）方法研究人白介素6受体胞外区配基结合功能域“WSXWS”区氨基酸残基定点突变对受体与配基人白介素6结合时的相互作用能量、分子间相互作用的影响,从分子力学、分子动态学分析了人白介素6受体胞外区功能域关键氨基酸残基在受体与配基结合中的构象变化以及与人白介素6间的相互作用.     

人白介素6与其受体结合特定结构域的预测

借助人白介素6的核磁共振构象, 以人生长因子受体为模板同源模建的人白介素6受体空间构象, 通过表观静电势分析, 结合空间构象的互补性对人白介素6与其受体进行分子对接, 在分子力学优化、分子动力学动态模拟的基础上获得稳定的复合物结构, 从理论上预测人白介素6与其受体相互作用的结构域, 进一步确定影响人白介素6与其受体相互作用的特定位点, 为确定靶蛋白人白介素6的活性部位、利用计算机寻找和辅助设计新的拮抗剂提供理论依据.     

白介素21及其对肿瘤的抑制作用

白介素21(interleukin-21, IL-21)是新近发现的具有多效免疫调节活性的细胞因子.遗传学和生化分析证实,IL-21是IL-2细胞因子家族的新成员.IL-21受体复合物包含γc-受体亚单位,活化后可引起JAK/STAT信号转导级联放大效应.IL-21由活化的CD4 T细胞合成,调节B细胞、T细胞、NK细胞和树突状细胞的增殖和分化.IL-21通过增强IgG抗体应答反应,抑制IgE合成而调节正常的体液免疫.IL-21也是重要的细胞免疫调节子,通过调节CD8 T细胞和NK细胞的活性清除鼠的肿瘤.     

白介素-33与炎症

白介素-33（interleukin-33,IL-33）是最近发现的一种前炎症细胞因子,它结合IL-1受体家族成员ST2,活化NF-κB和MAPK信号通路,促进Th2细胞因子的产生,参与多种炎症与免疫反应过程。本文就IL-33的分子结构、编码蛋白、产生及调节、受体信号与生物学活性等作综述。     

白介素-17A在小鼠慢性胰腺炎中的作用研究

目的:研究白细胞介素-17A在小鼠慢性胰腺炎模型中的表达及其对小鼠星状细胞的影响。方法:建立雨蛙肽诱导的小鼠实验性慢性胰腺炎动物模型,利用实时荧光定量PCR、ELISA、免疫组化和Western-blot等手段检测白介素-17A在雨蛙肽诱导的小鼠慢性胰腺炎模型中的表达变化及免疫活性。用重组白介素-17A作用于小鼠胰腺星状细胞,检测其对星状细胞活化的作用,并进一步探究其对促胰腺纤维化炎症因子白介素-6、白介素-1β、TGF-β在mRNA水平的表达变化。结果:慢性胰腺炎胰腺组织中白介素-17A受体IL-17RA及IL-17RC mRNA水平的表达较正常胰腺明显升高,慢性胰腺炎小鼠胰腺组织中IL-17A蛋白水平较正常小鼠明显升高,CP小鼠血清中IL-17A蛋白水平(56.40±10.50 pg/L)较NC组(27.88±5.74pg/L)亦明显升高,IL-17A在正常胰腺组织中鲜有表达(8.9±2.72%),而在CP组织中呈强阳性表达(55.84±5.71%),其免疫活性主要定位于间质炎性细胞及导管样复合体中;重组白介素-17A可促进小鼠星状细胞活化,并直接诱导星状细胞表达白介素-6、白介素-1β以及TGF-β等促纤维化细胞因子。结论:白介素-17A在雨蛙肽诱导的小鼠慢性胰腺炎模型中表达上调,并可能通过诱导小鼠星状细胞表达促炎细胞因子白介素-6、白介素-1β和TGF-β,促进胰腺星状细胞活化以及胰腺纤维化。     

变应性鼻炎患者血清IL-17和IL-17R表达及其与IgE的相关性

目的:探讨变应性鼻炎患者血清中IL-17及其受体的表达,及其与血清中总IgE的关系.方法:采用酶联免疫法检测51例健康志愿者(对照组)和37例变应性鼻炎患者(实验组)血清中IL-17,IL-17R及IgE的含量.结果:与对照组相比,变应性鼻炎患者血清IL-17,IL-17R及IgE的含量均明显升高.IL-17与变应性鼻炎患者血清中IgE成正相关(r=0.9678,P＜0.05),而IL-17R与IgE无明显相关性.结论:IL-17和IL-17R均参与变应性鼻炎的发病过程,可作为诊断变应性鼻炎的新指标,且降低IL-17的含量有助于变应性鼻炎的临床治疗.     

白细胞介素6受体

白细胞介素６受体（ＩＬ－６Ｒ）是造血生长因子受体家族的一员。它由一个８０ｋＤ的配基结合链（ＩＬ－６Ｒ）和作为信号转导子的非配基结合链ｇｐ１３０组成,ＩＬ－６Ｒ既能以膜受体形式存在,也能以可溶性受体形式存在。可溶性白介素６受体（ｓＩＬ－６Ｒ）同样具有膜受体的功能。白介素６受体的表达及调节在某些白介素６相关疾病的发病过程中起着重要作用。     

白介素17 与结直肠癌

结直肠癌是世界范围内的高发癌症,其发病机理尚不明确。大量研究数据表明,基因突变、表观遗传学的改变、饮食习惯以及生活方式等均是结直肠癌发生发展的高危因素。目前,普遍认为慢性炎症在肿瘤的发生发展中起重要作用。白介素17主要由T细胞的亚型Th17细胞分泌产生,能够促进肿瘤相关性炎症,使肿瘤细胞逃避免疫监控。已在胃癌、宫颈癌、食管癌、非小细胞肺癌、肝细胞肝癌、卵巢癌、黑色素瘤、淋巴瘤、乳腺癌、前列腺癌、结直肠癌等多种恶性肿瘤中发现白介素17呈高表达。现有研究表明,白介素17与肠炎和结直肠癌的发生发展密切相关。尽管尚存在争议,多数学者认为白介素17在结直肠癌的发生发展中起促进作用。本文将近年来关于IL-17在结直肠癌的发生发展中的作用以及其与结直肠癌的预后的研究成果进行总结。     

Shedding of Endogenous Interleukin-6 Receptor (IL-6R) Is Governed by A Disintegrin and Metalloproteinase (ADAM) Proteases while a Full-length IL-6R Isoform Localizes to Circulating Microvesicles

Generation of the soluble interleukin-6 receptor (sIL-6R) is a prerequisite for pathogenic IL-6 trans-signaling, which constitutes a distinct signaling pathway of the pleiotropic cytokine interleukin-6 (IL-6). Although in vitro experiments using ectopically overexpressed IL-6R and candidate proteases revealed major roles for the metalloproteinases ADAM10 and ADAM17 in IL-6R shedding, the identity of the protease(s) cleaving IL-6R in more physiological settings, or even in vivo, remains unknown. By taking advantage of specific pharmacological inhibitors and primary cells from ADAM-deficient mice we established that endogenous IL-6R of both human and murine origin is shed by ADAM17 in an induced manner, whereas constitutive release of endogenous IL-6R is largely mediated by ADAM10. Although circulating IL-6R levels are altered in various diseases, the origin of blood-borne IL-6R is still poorly understood. It has been shown previously that ADAM17 hypomorphic mice exhibit unaltered levels of serum sIL-6R. Here, by quantification of serum sIL-6R in protease-deficient mice as well as human patients we also excluded ADAM10, ADAM8, neutrophil elastase, cathepsin G, and proteinase 3 from contributing to circulating sIL-6R. Furthermore, we ruled out alternative splicing of the IL-6R mRNA as a potential source of circulating sIL-6R in the mouse. Instead, we found full-length IL-6R on circulating microvesicles, establishing microvesicle release as a novel mechanism for sIL-6R generation.     

Interleukin-17 in acute myeloid leukemia

There are several reports that angiogenesis plays important roles in hematological malignancies including acute myeloid leukemia (AML). Human interleukin-17 (IL-17) is a proinflammatory cytokine produced by activated CD4 T cells. IL-17 plays a potential role in T cell mediated angiogenesis. The role of IL-17 in pathologic angiogenesis has not been evaluated yet. The aim of the study was to determine plasma level of IL-17 in patients with AML. IL-17 levels were measured by ELISA in plasma samples taken from 68 adult patients with AML before chemotherapy was administered. In addition 20 out of 68 patients were reanalysed after achieving complete remission (CR). Ten samples from healthy volunteers were evaluated as the control. In this study we have demonstrated that serum level of IL-17 is not elevated in AML patients. These results suggest that angiogenesis in AML is not mediated by CD4 T cells. To our knowledge this is the first report about IL-17 serum level in acute leukemias. We are currently evaluating IL-17 levels in others haematological malignancies.     

Hypoxia enhances stimulating effect of amyloid beta peptide (25–35) for interleukin 17 and T helper lymphocyte subtype 17 upregulation in cultured peripheral blood mononuclear cells

Th17 has been demonstrated to have a key role in several autoimmune diseases. The present study was carried out to investigate changes in IL-17 and Th17 in cultured PBMC in response to Abeta peptide (25–35) and hypoxic stimulation in vitro . PBMC were collected from adult healthy donors and cultured in normal and anaerobic conditions (hypoxia 1, 3, 6, 12, 24 hr). Each group of cells was stimulated with Abeta peptide (25–35; 3, 10 nmol/ml). ELISA was used to examine IL-17A concentrations in the supernatants, and flow cytometry for the numbers of IL-17A secreting CD4 positive Th17 lymphocytes. Statistically significant increases in IL-17A and Th17 concentrations were found in groups with 10 nmol/ml Abeta (25–35) and more than three hr anaerobic culture. IL-17A and Th17 concentrations in anaerobic groups increased gradually with time and peaked at six hr. Compared with other groups, the highest concentrations were found in those treated with 10 nmol/ml Abeta and cultured for six hr ( P < 0.001). This study provides the first report that IL-17A and Th17 lymphocytes are possibly involved in the immune pathogenesis caused by Abeta peptide (25–35). Hypoxia may enhance this response independently of time.     

Enhancing Interleukin-6 and Interleukin-11 receptor cleavage

Proteolytic cleavage of the membrane-bound Interleukin-6 receptor (IL-6R) by the metalloprotease ADAM17 releases an agonistic soluble form of the IL-6R (sIL-6R), which is responsible for the pro-inflammatory trans-signaling branch of the cytokine's activities. This proteolytic step, which is also called ectodomain shedding, is critically regulated by the cleavage site within the IL-6R stalk, because mutations or small deletions within this region are known to render the IL-6R irresponsive towards proteolysis. In the present study, we employed cleavage site profiling data of ADAM17 to generate an IL-6R with increased cleavage susceptibility. Using site-directed mutagenesis, we showed that the non-prime sites P3 and P2 and the prime site P1′ were critical for this increase in proteolysis, whereas other positions within the cleavage site were of minor importance. Insertion of this optimized cleavage site into the stalk of the Interleukin-11 receptor (IL-11R) was not sufficient to enable ADAM17-mediated proteolysis, but transfer of different parts of the IL-6R stalk enabled shedding by ADAM17. These findings shed light on the cleavage site specificities of ADAM17 using a native substrate and reveal further differences in the proteolysis of IL-6R and IL-11R.     

IL-17 is involved in bone resorption in mouse periapical lesions

Periapical lesions are induced by bacterial infection of the dental pulp and result in destruction of the surrounding alveolar bone. Although various immunological studies concerning periapical bone resorption have been reported, the role of cytokines in the formation of periapical lesions remains unclear. In this study, the role of IL-17A in periapical lesions in mice was investigated. Normal C57BL/6, IFN-γ^−/−, TNF-α^−/−, and IL-17A^−/− mice were subjected to pulp exposure and infected with Prevotella intermedia (ATCC25611) and Porphyromonas gingivalis (ATCC33277) in the mandibular first molar. Periapical lesions were determined by μCT on day 21 after infection, and 3D visual construction was performed using 3D picture quantification software. The expression of IL-17A mRNA in periapical lesions was determined by the RT-PCR and real-time RT-PCR method. Periapical lesions developed in wild-type, IFN-γ^−/−, and TNF-α^−/− mice after infection with P. intermedia and P. gingivalis . However, periapical lesions were not observed in IL-17A^−/− mice. The expression of IL-17A mRNA was significantly induced in periapical lesions of wild-type mice after infection. These results suggest that IL-17A, but not IFN-γ or TNF-α, plays an important role in the formation of periapical lesions.     

免疫平衡的重要调节者白细胞介素-21

白细胞介素-21（IL-21）是γc家族的一个新成员,主要由活化的CD4＋ T细胞产生,对多种表达IL-21受体（IL-21R）的细胞如T细胞、B细胞、NK细胞及DC细胞等均有作用。近年发现IL-21与Th细胞系中新发现的分支Th17细胞的发生密切相关,在调节CD4＋ T细胞究竟是分化为Th17细胞还是CD4＋CD25＋Foxp3＋ Treg细胞中有＂开关＂作用,从而对免疫系统发挥重要的调节作用,在自身免疫性疾病和抗肿瘤免疫中扮演着重要的角色。简要综述了IL-21与Th17细胞、CD4＋CD25＋Foxp3＋ Treg细胞之间的关系及对免疫平衡的调节作用。     

Immunolocalization of IL-17A, IL-17B, and their receptors in chondrocytes during fracture healing.

Fracture healing in long bones is a sequential multistep cascade of hemostasis, transient inflammation, chemotaxis of progenitor cells, mitosis, differentiation of cartilage, and replacement with bone. This multistep cascade is orchestrated by cytokines and morphogens. Members of the interleukin (IL)-17 family, including IL-17B, have been identified in cartilage, but their expression during fracture healing is unknown. In this study, we determined the immunolocalization of cytokines IL-17A and IL-17B, along with the IL-17 receptor (IL-17R) and IL-17 receptor-like protein (IL-17RL), during the sequence of fracture repair in a standard model. The results were extended to developmental changes in the epiphyseal growth plate of long bones. Members of the IL-17 family were localized in chondrocytes in the fracture callus. Moreover, we found significant parallels to the localization of these cytokines and their receptors in chondrocytes during an endochondral differentiation program in the epiphyseal growth plate.     

甲状腺癌患者血清IL-17、IL-35、SIL-2R表达水平及其临床意义

目的:探讨甲状腺癌患者血清白细胞介素-17(IL-17)、白细胞介素-35(IL-35)及可溶性白介素-2受体(SIL-2R)水平及其对甲状腺癌诊断与病情评估的临床价值。方法:选取我院2015年6月~2016年12月收治的甲状腺腺瘤患者38例、甲状腺癌患者49例为研究对象,另选取同期于我院体检中心接受体检的52例健康体检者为对照组。采用酶联免疫吸附法(ELISA)检测和比较其血清IL-17、IL-35、SIL-2R水平,并分析甲状腺癌患者血清IL-17、IL-35、SIL-2R水平与其年龄、病程、病理分期的相关性。结果:甲状腺腺瘤组血清IL-17、IL-35、SIL-2R水平与对照组比较差异均无统计学意义(P0.05)。甲状腺癌组血清IL-35水平显著低于甲状腺腺瘤组和对照组(P0.01),血清IL-17、SIL-2R水平均显著高于甲状腺瘤组和对照组(P0.01)。血清IL-17、SIL-2R水平随甲状腺癌分化程度的降低而升高,血清IL-35水平随甲状腺癌分化程度的降低而降低(P0.01)。血清IL-17、SIL-2R水平随甲状腺癌病理分期的增加而升高,血清IL-35水平随甲状腺癌病理分期的增加而降低(P0.01)。血清IL-17、SIL-2R水平与甲状腺癌病理分期均呈显著正相关(r=0.432、0.439,P均0.05)。血清IL-35水平与甲状腺癌病理分期呈显著负相关(r=-0.602,P0.05)。血清IL-17与IL-35呈显著负相关(r=-0.323,P0.05),IL-17与SIL-2R呈显著正相关(r=0.429,P0.05),IL-35与SIL-2R呈显著负相关(r=-0.415,P0.05)。结论:甲状腺癌患者的血清IL-17、SIL-2R水平均显著上调,IL-35水平显著下调,其对甲状腺癌的早期诊断、病情评估均具有重要参考价值。     

Potential role of myeloid cell/eosinophil-derived IL-17 in LPS-induced endotoxin shock

IL-17RA is a shared receptor subunit for several cytokines of the IL-17 family, including IL-17A, IL-17C, IL-17E (also called IL-25) and IL-17F. It has been shown that mice deficient in IL-17RA are more susceptible to sepsis than wild-type mice, suggesting that IL-17RA is important for host defense against sepsis. However, it is unclear which ligands for IL-17RA, such as IL-17A, IL-17C, IL-17E/IL-25 and/or IL-17F, are involved in the pathogenesis of sepsis. Therefore, we examined IL-17A, IL-17E/IL-25 and IL-17F for possible involvement in LPS-induced endotoxin shock. IL-17A-deficient mice, but not IL-25- or IL-17F-deficient mice, were resistant to LPS-induced endotoxin shock, as compared with wild-type mice. Nevertheless, studies using IL-6-deficient, IL-21Rα-deficient and Rag-2-deficient mice, revealed that neither IL-6 and IL-21, both of which are important for Th17 cell differentiation, nor Th17 cells were essential for the development of LPS-induced endotoxin shock, suggesting that IL-17A-producing cells other than Th17 cells were important in the setting. In this connection, IL-17A was produced by macrophages, DCs and eosinophils after LPS injection. Taken together, these findings indicate that IL-17A, but not IL-17F or IL-25, is crucial for LPS-induced endotoxin shock. In addition, macrophages, DCs and eosinophils, but not Th17 cells or γδ T cells, may be sources of IL-17A during LPS-induced endotoxin shock.     

SEF/IL-17R (SEFIR) Is Not Enough: AN EXTENDED SEFIR DOMAIN IS REQUIRED FOR IL-17RA-MEDIATED SIGNAL TRANSDUCTION*

IL-17, the hallmark cytokine of the Th17 population, mediates immunity to extracellular pathogens and promotes autoimmune immunopathology. The signaling mechanisms triggered by the IL-17 receptor (IL-17RA) and related receptors are strikingly different from other cytokine subclasses. Namely, IL-17Rs contain a conserved SEF/IL-17R (SEFIR) subdomain that engages Act1, leading to activation of TRAF6, NF-κB, and other events. Although the SEFIR is critical for signaling, the molecular details of the functional subdomains within IL-17RA remain poorly characterized. Here, we provide a detailed structure-function analysis delineating the C-terminal boundary of the SEFIR-containing region of IL-17RA. We show that functionality of this domain requires a large extension to the previously identified SEFIR motif. In contrast to the SEFIR, this extension is not conserved among IL-17R family members. Surprisingly, Act1 recruitment is not sufficient for downstream signaling activation, whereas ubiquitination of TRAF6 correlates tightly with functional receptors. We further demonstrate that IL-17RA exhibits signaling properties that are nonredundant with other IL-17R family members. Finally, we report that IL-17 signals synergistically with lymphotoxin-α3, using the same signaling motifs within IL-17RA. These studies provide new insight into the structure-function relationships of IL-17RA and reveal distinct signaling differences among IL-17R family members.