Functional mapping of the Fc gamma RII binding site on human IgG1 by synthetic peptides

Receptors specific for the Fc part of IgG (Fc gamma R) are expressed by several cell types and play diverse roles in immune responses. Impaired function of the activating and inhibitory Fc gamma R may result in autoimmunity. Thus, the modulation of IgG-Fc gamma R interaction can be a target for the development of treatments for some autoimmune and inflammatory diseases. This study addresses the localization and functional characterization of linear sequences in human IgG1 which bind to Fc gamma RII. Peptides with overlapping sequences derived from the CH2 domain of human IgG1 between P(234) and S(298) were synthesized and used in binding and functional experiments. Binding of the peptides to Fc gamma R was assayed in vitro and ex vivo, and peptides found to interact were functionally tested. The shortest effective peptide was T(256)-P(271), which bound to soluble recombinant Fc gamma RIIb with K(d)=6 x 10(6) M(-1). The biotinylated peptides R(255)-P(271) and T(256)-P(271) complexed by avidin exhibited functional activity; they induced Fc gamma RIIb-mediated inhibition of the BCR-triggered Ca(2+) response of human Burkitt lymphoma cells, and inflammatory cytokine production (TNF-alpha and IL-6) by the human monocyte cell line MonoMac. In conclusion, our results suggest that the selected peptides functionally represent the Fc gamma RII-binding part of IgG1.     

Anti-inflammatory properties of human serum IgA: induction of IL-1 receptor antagonist and FcαR (CD89)-mediated down-regulation of tumour necrosis factor-alpha (TNF-α) and IL-6 in human monocytes

A deregulated expression and/or release of large amounts of inflammatory cytokines such as IL-1 and TNF-α accounts for most pathophysiological events in a variety of systemic inflammatory diseases, the effect being mediated by the interaction of these cytokines with their respective receptors. IL-1 receptor antagonist (IL-1Ra), mainly produced by monocytes/macrophages, is an inhibitor of IL-1 activity. The present study shows that human serum IgA induces significant IL-1Ra release in human peripheral blood mononuclear cells and adherent monocytes. IgA induced higher levels of IL-1Ra than Haemophilus influenzae type b (Hib) expressing lipopolysaccharide (LPS), purified LPS or phorbol myristate acetate (PMA), without induction of IL-1β release, and even inhibited LPS-induced IL-1β release. Induction of IL-1Ra by IgA could be detected both at the mRNA and protein levels in resting and activated monocytes. Ligation of FcαR with MoAb MY-43 or treatment with human serum IgA induced protein tyrosine phosphorylation in human monocytes, and herbimycin A, a specific inhibitor of protein tyrosine kinase activity, inhibited IgA-induced IL-1Ra production, suggesting that FcαR-mediated induction of tyrosine phosphorylation is required for the IgA-induced stimulation of IL-1Ra release. In addition, triggering of FcαR with MoAb specifically down-regulated TNF-α and IL-6 release in human monocytes activated with Hib. By the induction of IL-1Ra and down-regulation of the release of inflammatory cytokines such as IL-1β, TNF-α and IL-6, interaction of IgA with human monocytes may actively contribute to the regulation of the inflammatory response.     

Fc gamma RII alpha: sequencing of the ligand binding domain in systemic lupus erythematosus patients.

The receptor for the Fc portion of IgG (Fc gamma R) is involved in the slow clearance of immune complexes. To perform this role it must be cross-linked by IgG bound in its extracellular domains. It has been suggested that defective Fc gamma R-mediated clearance of immune complexes may play a role in the pathogenesis of autoimmune connective tissue disorders. We have sequenced DNA encoding the second extracellular domain of Fc gamma RII alpha in six patients with SLE, to investigate whether point mutations may be responsible for encoding a defect in the IgG binding capacity of the receptor. We were able to identify the point mutation which discriminates high and low responder genotypes but found no other change from the published DNA sequence for this region.     

miR-143-3p靶向IL-6R/STAT3通路抑制IL-6诱导的人肺微血管内皮细胞血管生成

目的探究miR-143-3p在IL-6诱导的人肺微血管内皮细胞(HLMVEC)血管生成中的作用和机制。方法首先使用100 ng/ml重组IL-6蛋白处理HLMVEC细胞,管腔形成实验分析IL-6对细胞管腔形成数目的影响,Real-time PCR检测IL-6对miR-143-3p和VEGF mRNA表达的影响。Western blot检测VEGF蛋白水平的变化。然后使用miR-143-3p mimics过表达miR-143-3p,按照上述方法检测miR-143-3p对IL-6诱导的管腔形成数目、VEGF mRNA和蛋白表达的影响。此外,使用双荧光素酶报告基因检测法分析miR-143-3p和IL-6R的关系,Real-time PCR检测miR-143-3p过表达对IL-6R mRNA表达的影响,Western blot检测IL-6R、STAT3和磷酸化STAT3(p-STAT3)蛋白水平的变化。结果 IL-6能够增加管腔形成数目和VEGF的表达,降低miR-143-3p的表达。过表达miR-143-3p能够抑制IL-6诱导的管腔形成、VEGF、IL-6R和p-STAT3的表达水平,但是不影响STAT3的表达。此外还发现IL-6R是miR-143-3p的一个靶基因。结论 miR-143-3p能够抑制IL-6诱导的内皮细胞血管生成,这可能是通过抑制IL-6R/STAT3通路发挥作用的。     

Regulation of the expression of Fc gamma receptor on circulating neutrophils and monocytes in Kawasaki disease.

To investigate the regulation of Fc gamma receptor (Fc gamma R) expression on circulating phagocytes in Kawasaki disease (KD), we analysed the expressions of Fc gamma RI, II and III on neutrophils and monocytes in 20 patients with KD, 10 with a bacterial infection (BI), 10 with a viral infection (VI), and 10 healthy controls (HC) using flow cytometric analysis. The KD patients had a significantly higher level of Fc gamma RI expression on neutrophils, but not on monocytes, than the BI, VI and HC patients. Fc gamma RII expression on neutrophils was significantly higher in KD, BI and VI than HC, but there was no significant difference in Fc gamma RII expression among KD, BI and VI. Fc gamma RIII expression on neutrophils in KD was significantly lower than in VI and HC, but was higher on monocytes. A kinetic analysis of Fc gamma R expression in KD demonstrated the expression of Fc gamma RI and II on neutrophils to decline, but no remarkable change was observed in the monocytes, from the subacute phase through the convalescent phase. In addition, Fc gamma RIII expression on neutrophils increased, while Fc gamma RIII expression on monocytes decreased during the time course of KD. Fc gamma R expression in the acute phase of KD is thus characterized by markedly increased expression of Fc gamma RI on neutrophils, followed by a subsequent decrease, and decreased expression of Fc gamma RIII on neutrophils and increased expression of Fc gamma RIII on monocytes followed by a reverse kinetics during the clinical course. These findings are thus considered to reflect the functional up-regulation of neutrophils and monocytes in KD.     

IL-6 and soluble IL-6 receptors (sIL-6R and sgp130) in human pleural effusions: massive IL-6 production independently of underlying diseases

IL-6, soluble IL-6 receptor (sIL-6R) and soluble gp130 (sgp130) levels were measured in sera and pleural effusions from 42 patients with metastatic carcinoma, non-Hodgkin's lymphoma, tuberculosis, cardiac failure and miscellaneous diseases. Pleural IL-6 levels measured by ELISA were very high in all patient groups (mean 34.8 ± 15.3 ng/ml) without significant difference according to diseases. IL-6 was shown to be biologically active in a proliferative assay. Serum IL-6 levels were low (0.049 ± 0.014 ng/ml) and did not correlate with pleural fluid levels. Pleural IL-6 levels correlated with the number of polymorphonuclear cells in pleural fluid (P< 0.03). Pleural sIL-6R levels (76 ± 8 ng/ml) were always lower than serum levels (196 ± 12 ng/ml; P< 0.0001) but correlated with them (P< 0.01). Pleural sIL-6R and albumin levels correlated (P< 0.01), suggesting a transudation of sIL-6R from the serum. Pleural sgp130 levels (10.9 ± 1.0 ng/ml) were lower than serum levels (24.6 ± 2.8 ng/ml; P< 0.002). After gel filtration of pleural fluid, the bulk of IL-6 (>90%) was recovered in a 15 000–30 000 fraction, corresponding to the expected mol. wt of free IL-6. These results suggest a production and a sequestration of IL-6 in the pleural cavity in all studied conditions.     

Roles of the transmembrane domain and the cytoplasmic domain of Fc epsilon RI alpha in immunoglobulin E-mediated up-regulation of surface Fc epsilon RI expression.

BACKGROUND: Human mast cells express both Fc epsilon RI alpha and Fc gamma RI alpha. IgE up-regulates Fc epsilon RI alpha expression, but IgG1 does not up-regulate Fc gamma RI alpha expression. The transmembrane domain (TM) of Fc gamma RI alpha determines the stability of cell surface expression of this receptor. OBJECTIVE: The aim of this study was to clarify the roles of the TM and cytoplasmic domain (CY) of Fc epsilon RI alpha in IgE-mediated Fc epsilon RI up-regulation. METHODS: Chimeric receptors created by domain shuffling between Fc epsilon RI alpha and Fc gamma RI alpha were transduced into human mast cell line HMC-1. Cell surface expression of the chimeric receptors and the effect of IgE or IgG1 on chimeric receptor expression were examined by FACS. The association of the chimeric receptors with FcR gamma was investigated by immunoprecipitation. RESULTS: The results showed that the TM and CY of Fc epsilon RI alpha are not essential for IgE-mediated up-regulation of surface Fc epsilon RI. CONCLUSION: The extracellular domain of each Fc receptor determines the diversity of Ig-regulated Fc receptor expression.     

Selection of a human anti-RhD monoclonal antibody for therapeutic use: impact of IgG glycosylation on activating and inhibitory Fc gamma R functions

The substitution of plasmatic anti-RhD polyclonal antibodies by a monoclonal antibody (mAb) for preventing the hemolytic disease of the newborn (HDN) is an important issue due to supply and safety concerns. Since it has been suggested that FcgammaR are involved in the prevention of HDN, the in vitro functional properties of two anti-RhD mAbs differing through their glycosylation profiles were compared using FcgammaR-based assays to select a candidate mAb. T125(YB2/0), a low fucosylated antibody, bound strongly to both activating FcgammaRIII and inhibitory FcgammaRII, as opposed to its highly fucosylated counterpart. It also exerted a strong ADCC against RhD+ RBCs and a potent FcgammaRIIB-mediated inhibition of cytokine release. Moreover, an in vivo RhD+ red blood cells (RBCs) clearance assay showed that this antibody exhibits a RhD+ RBCs clearance as potent as polyclonal anti-RhD antibodies in NOD-SCID mice. Thus, T125(YB2/O) has been selected to be tested for the prevention of anti-RhD allo-immunization.     

Autostimulatory effects of IL-6 on excessive B cell differentiation in patients with systemic lupus erythematosus: analysis of IL-6 production and IL-6R expression.

Introducing avidin-biotin complex ELISA for anti-DNA antibody, the mechanism of in vitro production of anti-ssDNA antibody as well as of polyclonal immunoglobulin mediated by an IL-6-IL-6R loop was studied in patients with systemic lupus erythematosus (SLE). Regardless of the presence or absence of T cells, B cells from SLE patients could produce IgG anti-ssDNA antibody as well as total IgG without any stimulation. Low density B cells obtained by Percoll gradient density centrifugation responded to rIL-6 to produce IgG and IgG anti-ssDNA antibody. rIL-2 and rIL-4 had lesser effects on the differentiation of low density B cells. In fact, IL-6R was preferentially expressed on low density B cells from active SLE patients, as detected by anti-IL-6R MoAb, MT18, which did not inhibit IL-6 binding. SLE B cells, especially high density B cells, produced greater amounts of IL-6 in culture supernatants than did T cells, regardless of whether disease was active or inactive. Normal T cells and B cells did not produce significant amounts of IL-6. Thus, endogenous IL-6 produced by high density B cells bound to the IL-6R preferentially expressed on the low density B cells, and drove them into terminal differentiation, especially in active SLE patients. Further, addition of polyclonal anti-IL-6 or anti-IL-6R MoAb (PM1), which inhibited IL-6 binding, both inhibited IgG anti-ssDNA antibody as well as total IgG production by SLE B cells in a dose-dependent manner. These results suggest that interruption of the autocrine IL-6 loop would be of therapeutic value in SLE.     

Fc epsilon receptor II/CD23+ lymphocytes in atopic dermatitis. III. Aberrant control in the in vitro expression of Fc epsilon RII/CD23 on peripheral blood T cells in atopic dermatitis.

In vitro Fc epsilon RII expression was examined in patients with atopic dermatitis, those with non-atopic eczematous dermatitis and normal individuals following stimulation of peripheral blood cells with recombinant IL-4 (rIL-4), phytohaemagglutinin (PHA), or PHA plus rIL-2. At various days cells were stained with MoAbs to human lymphocyte Fc epsilon RII and to lymphoid cell-surface antigens and analysed by flow cytometry. rIL-4, but not rIL-2, specifically induced Fc epsilon RII on T cells as well as B cells in atopic dermatitis, eczematous dermatitis and normal individual groups. Both atopics and non-atopics generated comparable proportions of Fc epsilon RII+ T cells (T epsilon cells), whereas the frequency of B cells bearing Fc epsilon RII(B epsilon cells) was significantly higher in patients with extensive atopic dermatitis than in those with mild atopic dermatitis and other subjects. Comparable levels of T epsilon cells were detected in both atopic and non-atopic donors following stimulation of peripheral blood cells with PHA or pre-activation of the cells with PHA plus subsequent incubation with rIL-2. Whereas both CD8+ and CD4+ subsets were present in T epsilon cell populations induced specifically by rIL-4, PHA and PHA plus rIL-2, patients with atopic dermatitis had a greater tendency for Fc epsilon RII expression on CD8+ T cells compared with patients with eczematous dermatitis and normal individuals. Recombinant interferon-gamma (rIFN-gamma), but not rIFN-alpha or prostaglandin E2 (PGE2), suppressed the generation of T epsilon cells by rIL-4 in atopics and non-atopics to the same degree. These results suggest the aberrant control of Fc epsilon RII expression on T cells, especially those bearing CD8, in atopic dermatitis.     

Early induction of IL-1 receptor antagonist (IL-1Ra) in infants and children undergoing surgery.

The cytokine response to injury or trauma is of interest in terms of both its mediation of the acute phase response and its possible relation to the immunological depression observed after major surgery. In this study, the production of cytokines IL-1 beta, tumour necrosis factor-alpha (TNF-alpha), IL-6 and the naturally occurring inhibitor of IL-1, IL-1Ra, have been investigated in infants and children undergoing Swenson's pull-through operation for Hirschsprung's disease. Samples of peripheral blood were taken before, during and after surgery for the measurement of cytokines. IL-1Ra levels increased significantly (P < 0.01) at 2 h after commencement of surgery, with maximal levels for individual patients being attained between 3 h and 5 h (range 7.6-67.9 ng/ml). The mean level of IL-1Ra was maximal (26.2 ng/ml) at 5 h and returned to baseline levels between 24 h and 72 h. There were no changes observed in the circulating levels of IL-1 beta in nine out of 11 patients following commencement of surgery. TNF-alpha levels did not increase in any of the patients studied. IL-6 levels increased significantly (P < 0.02) 3 h after commencement of surgery, reaching maximum concentrations at 24 h (range 20-670 pg/ml), with levels falling between 48 h and 72 h. This study demonstrates, in vivo, the independent induction of IL-1Ra without a concomitant increase of IL-1 beta levels after major surgery. It also shows that IL-1Ra is the earliest cytokine produced in response to surgical stress.     

Requirement of high-affinity IL-2-IL-2R interaction for T cell anergy induction

Incomplete T cell antigen receptor-mediated signaling induces an unresponsive state known as anergy. Previously, we had shown that anergy can be induced in antigen-primed but not naive T cells. In this report, we found that in vitro primed T cells from IL-2R alpha-deficient mice were resistant to anergy induction in contrast to comparably treated wild-type T cells. This resistance persisted even after proliferation of IL-2R alpha chain-deficient CD4 T cells with high-dose IL-2-IL-2R beta gamma chains interaction. Thus, antigen activation, and/or progression through cell cycle are not sufficient to induce anergy susceptibility in T cells. The high-affinity IL-2-IL-2R interaction appears to play a critical role in this process.     

急性白血病患者IL-6,TNF-α和sIL-6R含量及其与白血病负荷的相关性

应用生物学检则法,ELISA法和间接免疫荧光法分析了24例急性白血病患者外周血IL-6,sIL-6R和TNF-α的含量及其与白血病细胞负荷的相关性.结果显示:(1)急性白血病患者外周血IL-6,sIL-6R及TNF-α水平明显升高,其中急性B淋巴性白血病(B-ALL)的IL-6,sIL-6R及急性T淋巴性白血病(T-ALL)的TNF-α升高尤为明显;(2)B-ALL的IL-6,TNF-α及T-ALL的TNF-α水平与白血病细胞负荷有着较好的正相关性;而sIL-6R水平与白血病细胞负荷则无明显的相关.由此表明不同类型的白血病存在不同的有利于肿瘤细胞生长的生物因子微环境,这些生物因子及其受体的异常表达与白血病的发生发展相关.     

人可溶性IL-6R及其突变体基因在COS7细胞中的表达及活性分析

目的 研究人可溶性ＩＬ－６Ｒ（ｈｓＩＬ－６Ｒ）的空间构效关系,为小分子拮抗设计提供理论依据。方法：首先利用ＰＣＲ技术扩增天然人ｓＩＬ－６Ｒ基因片段,然后将第２８０位Ｈｉｓ残基突变成Ｉｌｅ。天然基因和突变体基因分别转染ＣＯＳ７细胞,经ＥＬＩＳＡ和Ｗｅｓｔｅｒｂｌｏｔ检测证实转染细胞上清中的表达产物,并利用ＢｉｎｄｉｎｇａｓｓａｙＥＬＩＳＡ和生物学功能分析法检测表达产物与ＩＬ－６的结合能力以及它们所介     

Perioperative serum levels of tumour-necrosis-factor alpha (TNF-alpha), IL-1 beta, IL-6, IL-10 and soluble IL-2 receptor in patients undergoing cardiac surgery with cardiopulmonary bypass without and with correction for haemodilution.

Cardiac surgery with cardiopulmonary bypass (CPB) leads to a systemic inflammatory response with secretion of cytokines. Alterations in the serum concentrations of cytokines have important prognostic significance. Reports on cytokine release during cardiac surgery with CPB have yielded conflicting results. Haemodilution occurs with the onset of CPB resulting in large fluid shifts during the perioperative course of cardiac procedures. In the present study we compare the perioperative course of serum concentrations of TNF-alpha, IL-1beta, IL-6, IL-10 and sIL-2R with and without correction for haemodilution in patients undergoing coronary artery bypass grafting (CABG) surgery. Twenty male patients undergoing elective CABG surgery with CPB and general anaesthesia using a balanced technique with sufentanil, isoflurane and midazolam were enrolled into the study. Serum levels of TNF-alpha, IL-1beta, IL-6, IL-10 and sIL-2R were measured using commercially available ELISA kits. Simultaneous haematocrit values were obtained at all sample times. Statistical analysis was performed by non-parametric analysis of variance and t-tests for data corrected for haemodilution and data that were not corrected for haemodilution. Adjusted significance level was P < 0.01. Intra-operatively, up to the second post-operative day PCV values were significantly decreased compared with preoperative values. Cytokine measurements not corrected for haemodilution were significantly lower than the corrected values. The perioperative haemodilution and decrease in PCV may lead to an underestimation of the cytokine secretion in post-operative patients. We conclude that cytokine measurements were significantly influenced by the perioperative haemodilution and the subsequent decrease in PCV and may in part account for the varying results reported in the literature regarding cytokine release in patients undergoing CABG surgery.     

慢性丙肝患者血清IL-6、IL-10、IL-32水平与HCV-RNA载量关系研究

目的探究慢性丙肝患者血清白细胞介素-6(IL-6)、白细胞介素-10(IL-10)、白细胞介素-32(IL-32)水平与丙型肝炎病毒RNA(HCV-RNA)载量的关系。方法选择我院于2015年3月至2018年3月收治的慢性丙型肝炎(CHC)患者90例为CHC组,同期以90例来我院进行健康体检的健康者为健康组,采用ELISA法检测所有受试者的血清IL-6、IL-10、IL-32水平,采用PE5700荧光PCR仪和实时荧光定量聚合酶链反应法检测CHC组患者的HCV-RNA载量,对比CHC组患者和健康组受试者的血清IL-6、IL-10、IL-32水平;对不同病毒载量的CHC患者血清IL-6、IL-10、IL-32水平进行对比,并分析病毒载量与检测指标之间的相关性。结果经对比,CHC组患者的血清IL-6、IL-10、IL-32水平均显著高于健康组受试者(P<0.05);随着病毒载量的不断增大,CHC患者的IL-6、IL-10、IL-32水平均显著升高(P<0.05);通过Pearson相关性分析结果显示,血清IL-6、IL-10、IL-32水平均与HCV-RNA载量显著相关,且为正相关。结论慢性丙肝患者血清IL-6、IL-10、IL-32水平与HCV-RNA载量呈正相关,可通过检测机体的血清IL-6、IL-10、IL-32水平了解丙型肝炎的发病机制和慢性化过程,对临床诊断慢性肝炎、了解疾病进展、评价治疗效果等意义重大。     

LPS对人胚胎胰岛分泌IL-6的调控效应

目的：为了探讨免疫介质ＬＰＳ对胚胎胰岛分泌ＩＬ－６以及对胰岛功能的影响,以便为研究免疫系统与内分泌系统的内在联系提供依据。方法：采用用常规消化方法分离人胚胎胰岛并对其进行原代培养,加入浓度为１０ｍｇ／Ｌ ＬＰＳ,经不同时相收获上清,测定ＩＬ－６、胰岛素、胰高血糖素含量和ＩＬ－６ ＭＣ或的试验,对ＬＰＳ刺激和对照一胰岛进行ＩＬ－６ ＲＮＡ斑点杂交。结果：１．人胚 ＬＰＳ刺激分泌ＩＬ－６的能力明显加强     

Human herpesvirus 6 induces IL-8 gene expression in human hepatoma cell line,Hep G2

The infectivity of human herpesvirus 6 (HHV-6) in a human hepatoma cell line, Hep G2 cells, and the effect of HHV-6 on production of inflammatory cytokines in these cells were examined to analyze pathogenesis of HHV-6 in the liver. We demonstrated that Hep G2 cells were susceptible to infection with HHV-6, and produced infectious virus. Moreover, infection of Hep G2 cells by HHV-6 induced the expression of IL-8 mRNA, but not IL-1β. The effect on induction of IL-8 gene expression was observed only in Hep G2 cells infected with infectious virus, whereas both heat-inactivated HHV-6 and UV-irradiated HHV-6 did not change the IL-8 mRNA level in these cells. These data suggest that HHV-6 may induce the cytokine-mediated inflammatory response by infecting liver cells, which could result in liver dysfunction in vivo. © 1996 Wiley-Liss, Inc.