Soluble interleukin-6 receptor (sIL-6R), a new prognostic factor in multiple myeloma

sIL-6R is a 55 kD soluble molecule mediating the interleukin-6 (IL-6) signal through the IL-6 receptor-associated transmembrane signal transducer, gp130. It has recently been suggested that sIL-6R serum levels may reflect disease severity in multiple myeloma (MM). We determined sIL-6R serum levels in 25 normal controls (NC) and in 80 MM patients at diagnosis and during the course of the disease. Measurements were done by ELISA. In NC, sIL-6R levels ranged from 14 to 40 ng/ml (median 28 ng/ml) whereas in MM patients the range was 10–200 ng/ml (median 38 ng/ml) ( P  < 0.01). 61 patients entered remission and 19 were resistant. Median sIL-6R value at diagnosis was 36 ng/ml (10–120) in responding patients, and 82 ng/ml (20–200) in non-responding patients ( P  < 0.001). During a follow-up from 12 to 89 months, sIL-6R values remained more or less stable in most patients. High sIL-6R levels correlated with poor survival.     

Soluble interleukin-6 receptor as a prognostic factor in multiple myeloma

Interleukin-6 (IL-6) is a major growth factor for the clonal malignant plasma cells in multiple myeloma (MM). The effect of IL-6 may be enhanced by soluble IL-6 receptor (sIL-6R). As there is a clinical need for improved stratification of MM patients at diagnosis, we have studied the role of sIL-6R as a prognostic marker in 207 newly diagnosed MM patients. Serum sIL-6R concentration was above the upper reference limit in 47% of the patients at diagnosis. The concentrations of sIL-6R and two other prognostic factors, IL-6 and β-2 microglobulin (β2M), were all significantly higher in the patients who died within 3 years compared with those who survived. However, serum sIL-6R did not show linear correlation with IL-6 or β2M levels. In univariate logistic regression analysis sIL-6R was a significant predictor of 3-year mortality. Kaplan-Meier analysis showed that raised levels of sIL-6R were associated with shorter survival. When the patients were stratified into four groups according to their serum IL-6 and sIL-6R levels, the patients with normal serum levels of both parameters had clear survival benefit. As β2M was the most powerful prognostic factor in the multivariate analysis, the patients were also stratified according to their serum β2M and sIL-6R levels. The patients with raised levels of both β2M and sIL-6R had shorter survival than the patients in the other three groups. Thus, measurement of these parameters at diagnosis would help to stratify MM patients.     

Clinical significance of elevated soluble interleukin-6 receptor levels in the sera of patients with plasma cell dyscrasias

Summary .We investigated the clinical significance of the serum soluble interleukin-6 receptor (sIL-6R) in 42 patients with plasma cell dyscrasias (27 with multiple myeloma (MM), 13 with monoclonal gammopathy of undetermined significance (MGUS), and two with plasma cell leukaemia (PCL)). Serum levels of sIL-6R in normal individuals were 77 ± 21 ng/ml (mean ± SD, n = 18); those in patients with MGUS and with MM were elevated (102 ± 33 ng/ml, mean ± SD, P < 0–05 and 126 ± 60ng/ml, mean ± SD, P < 0–01, respectively). Significant correlations were not found between the serum levels of sIL-6R and known prognostic factors (C-reactive protein, haemoglobin levels, calcium, creatinine, β₂-microglobulin, amounts of M-protein, or percentages of plasma cells in bone marrow). Elevated serum sIL-6R did not affect the survival of the patients with MM. Serial measurements of sIL-6R together with the clinical course of patients with plasma cell neoplasias revealed a good correlation between the sIL-6R level and disease activity. We conclude that sIL-6R can be used as a clinical factor correlated with the disease activity, at least in some patients with plasma cell neoplasias.     

Serum concentrations of proinflammatory cytokines in Graves' disease: effect of treatment, thyroid function, ophthalmopathy and cigarette smoking

OBJECTIVE: In the present study we have measured the concentrations of interleukin-6 (IL-6), soluble IL-6 receptor (sIL-6R), tumor necrosis factor-alpha (TNF-alpha), interleukin-1 beta (IL-1 beta) and IL-1 receptor antagonist (IL-1Ra) in the serum of patients with Graves' disease (GD). By multivariate analysis, we have evaluated the effect of antithyroid treatment, thyroid function, the presence or absence of active thyroid-associated ophthalmopathy (TAO), the patient's smoking habits and the relation to circulating anti-thyrotropin (TSH) receptor (TRAb) and anti-thyroperoxidase antibodies (TPOAb). SUBJECTS: We studied 84 GD patients, 51 untreated and 33 receiving methimazole (MMI) therapy. Twenty-three (45%) untreated patients and 18 (54%) patients on MMI had active TAO. We also studied 67 normal subjects as controls. Thirty-one GD patients (43%) and 16 controls (36%) were smokers. RESULTS: Serum IL-6 concentrations were significantly higher in both untreated patients (P<0.001) and treated patients (P<0.006), when compared with controls. Serum sIL-6R concentrations were significantly affected by treatment (P=0.001). Serum IL-1Ra concentrations were not different in GD patients, whether treated or untreated, compared with controls. Serum IL-6 concentrations were not influenced by thyroid function and there was a significant interaction between treatment and the presence of active TAO (P=0.003). In hyperthyroid patients with active TAO serum, sIL-6R concentrations were significantly higher than in those with inactive TAO (P=0.003). In untreated GD patients there was no significant effect of thyroid function and TAO activity on the serum concentrations of TNF-alpha and IL-1 beta. Serum IL-1Ra concentrations were not affected by the presence of TAO. Smoking had no effect on serum IL-6, sIL-6R, TNF-alpha, IL-1 beta and IL-1Ra concentrations, even in the presence of an active TAO. Serum concentrations of IL-6, sIL-6R, TNF-alpha and IL-1 beta and IL-1Ra were not different in patients with and without TRAb or TPOAb, in relation to either thyroid function, TAO activity or smoking. CONCLUSIONS: Our work shows that: (i) the proinflammatory cytokine pattern in GD is greatly influenced by antithyroid drug treatment; (ii) the increased circulating IL-6/sIL-6R concentrations observed in patients with active TAO may derive from the activation of humoral reactions in sites other than the thyroid; and, (iii) cigarette smoking has no effect on serum IL-1/IL-1Ra concentrations in TAO.     

川崎病患儿血清可溶性白细胞介素-2受体和白细胞介素-6的变化及意义

目的探讨血清可溶性白细胞介素-2受体(sIL-2R)和白细胞介素-6(IL-6)水平在川崎病(K D)患儿中的变化,及其在发病中的作用。方法采用酶联免疫吸附试验(ELISA)双抗夹心法测定血清sIL-2R和IL-6水平;利用德灵BN ProSpec特种蛋白分析仪检测血清超敏C反应蛋白(hs-CRP)水平。结果30例KD患儿大剂量丙种球蛋白静脉滴注前(静丙前)和滴注后(静丙后)血清slL-2R和hs-CRP水平与对照组比较差异均有统计学意义(P<0.01),静丙前和静丙后比较差异有统计学意义(P<0.01);静丙前KD患儿血清IL-6和对照组比较差异有统计学意义(P<0.01);KD患儿血清slL-2R与hs-CR P水平呈正相关(r=0.6,P<0.01),静丙前K D患儿血清IL-6和hs-CRP呈正相关(r=0.68,P<0.01)。结论血清IL-6和slL-2R参与了川崎病的发生,它们可作为判断预后、评估患儿免疫功能状况的参考指标。     

Interleukin-6, soluble interleukin-2 receptor and soluble interleukin-6 receptor in the sera of patients with different histological patterns of rheumatoid synovitis

OBJECTIVE: The present study was conducted to investigate whether the serum levels of interleukin 6 (IL-6), soluble IL-2 receptor (sIL-2R) and sIL-6R are associated with the morphological appearance of rheumatoid arthritis (RA). METHODS: Using the ELISA technique we measured the IL-6, sIL-2R and sIL-6R concentrations in the serum of 34 patients with RA and 28 patients with osteoarthritis (OA). Histological analysis of synovial samples distinguished 2 types of rheumatoid synovitis. Twenty-one RA specimens presented diffuse infiltrates of mononuclear cells without any specific microanatomical organization. In remaining 13 samples the formation of lymphocytic follicles with germinal center-like structures was found. RESULTS: Serum levels of IL-6, sIL-2R and sIL-6R were elevated in patients with RA compared to the OA control group (p < 0.001, p < 0.001 and p < 0.05 respectively). Concentrations of IL-6 and sIL-2R were highest in the serum of RA patients with follicular synovitis in comparison to patients with diffuse synovitis (p < 0.001 and p < 0.01 respectively) and could distinguish RA patients with these two histological variants of the disease. Serum levels of IL-6 and sIL-2R correlated with markers of disease activity such as ESR and CRP levels. In addition, the clinical data suggest a more severe disease among RA patients with follicular synovitis. CONCLUSION: Distinct histological types of rheumatoid synovitis associated with unique serum concentrations of IL-6 and sIL-2R reflect levels of disease activity and confirm the concept of RA heterogeneity.     

Oestrogens prevent the increase of human serum soluble interleukin-6 receptor induced by ovariectomy in vivo and decrease its release in human osteoblastic cells in vitro

OBJECTIVE: Interleukin-6 (IL-6) seems to be a key mediator of the increased bone loss that follows loss of ovarian function. Based on this and on evidence that oestrogen deficiency may also increase cell sensitivity to IL-6, we studied the effects of ovariectomy and of oestrogen replacement therapy on the serum levels of IL-6 and of soluble IL-6 receptor (sIL-6R) in vivo. DESIGN AND PATIENTS: Thirty-seven fertile women undergoing surgery for benign uterine diseases were divided into 3 groups and monitored for 12 months: hysterectomized women (n = 9), ovariectomized untreated women (n = 12) and ovariectomized women starting treatment with transdermal estradiol (E2, 50 microg/d) 1 month after surgery (n = 16). RESULTS: Hysterectomy alone caused no significant changes of sIL6R whereas serum levels of sIL-6R rose progressively after ovariectomy (mean +/- SEM: 31 +/- 9% and 38 +/- 7% over baseline, at 6 and 12 months, respectively; P < 0.01). Oestrogen replacement therapy prevented the increase of sIL6R over a 1-year period. A similar pattern was also found for serum IL-6 but the changes did not reach statistical significance. In ovariectomized (OVX) women there were significant correlations between serum sIL-6R levels and FSH (r = 0.59; P < 0. 01), oestradiol (r = - 0.43; P < 0.01), testosterone (r = - 0.41; P < 0.05), osteocalcin (r = 0.42; P < 0.05) and bone alkaline phosphatase (r = 0.44; P < 0.05). To examine whether oestrogen directly regulates sIL-6R secretion by bone cells, we studied in vitro the basal and phorbol ester (PMA) stimulated release of sIL-6R in a human osteoblastic cell-line (MG-63) and in a tumour-derived osteoclastic cell line (GCT-51). Osteoblastic (but not osteoclastic) cells spontaneously produced considerable amounts of sIL-6R and the protein kinase-C activator PMA (10-8 M) increased the release of sIL-6R by osteoblasts more than 3-fold. More strikingly, 17beta E2 (but not 17alpha) significantly inhibited both the spontaneous- and PMA-induced release of sIL-6R by osteoblastic cells (P < 0.05). CONCLUSIONS: These results indicate that oestrogen loss causes alterations of the IL-6 system, and that sIL-6R is under the direct inhibitory control of oestrogens both in vivo and in vitro.     

Incidence of apoptosis and cell proliferation in multiple myeloma: correlation with bcl-2 protein expression and serum levels of interleukin-6 (IL-6) and soluble IL-6 receptor

We evaluated the in vivo incidence of apoptosis and cell proliferation in multiple myeloma (MM) and investigated the correlation of both cellular events with histological tumour stage and grade, bcl-2 protein expression, serum IL-6 and sIL-6R. MATERIAL AND METHODS: The TUNEL method was used to assess apoptosis and immunohistochemistry to assess the expression of proliferating cell nuclear antigen (PCNA) and bcl-2 protein in 30 bone marrow biopsy specimens. The apoptotic index (AI) and proliferative index (PI) were defined as the percentage of TUNEL and PCNA positive plasma cells, respectively. RESULTS: The mean AI was 0.162% and the mean PI 27.44%. A positive correlation between AI and PI was found (r = 0.44, P = 0.017). PI was also correlated with tumour grade (P = 0.015). The mean bcl-2 protein expression was 70% and did not correlate with AI or PI, but was higher in specimens taken at first diagnosis than in specimens taken after response to treatment (P = 0.035). The mean serum IL-6 and sIL-6R values were 9.43 pg mL-1 and 47.27 ng mL-1, respectively. These parameters did not correlate with AI or PI. CONCLUSIONS: The results indicate that MM might be among the malignancies with very low incidence of apoptosis. Proliferative activity increased in parallel with tumour histological grade. A positive correlation between apoptosis and proliferation was observed, but the incidence of these two cellular events seems not to be related to the bcl-2 protein expression and the serum levels of IL-6 and sIL-6R.     

Frequently relapsing Crohn's disease is characterized by persistent elevation in interleukin-6 and soluble interleukin-2 receptor serum levels during remission

We examined immune and inflammatory activation during remission in patients with Crohn's disease who presented with various clinical profiles (prolonged remission vs. relapsing disease). Thirty-six patients with at least 3 years' follow-up starting from a remission period were studied retrospectively. Relapses were defined by a retrospective calculation of the Crohn's disease activity index or by the clinical judgement of the physicians in charge of the patients. Disease course over the study period was assessed by the mean number of annual relapses. Analysis used measurements during remission of the following: erythrocytes sedimentation rate, relative lymphocytosis, acid alpha1-glycoprotein, interleukin-6 (IL-6), and soluble interleukin-2 receptor (sIL-2R) serum levels. During the study period 21 patients experienced at least one relapse and 15 did not. Mean serum levels of sIL-2R and mean relative lymphocytosis in remission significantly discriminated between relapsing and nonrelapsing patients. Only the mean sIL-2R serum level was selected by multivariate analysis, with a cutoff value of 82 pM/1 (sensitivity of 76% and specificity of 80%). The only features correlated with mean number of annual relapses in the relapsing patients were mean serum levels of sIL-2R (r=0.58, P=0.015) and IL-6 in remission (r=0.45, P=0.039). Multivariate analysis demonstrated statistical significance only for the mean serum level of IL-6 (P=0.014). In Crohn's disease the persistent elevation in sIL-2R serum levels during remission corresponds to chronic active disease, while high serum levels of IL-6 in these patients is associated with a high frequency of relapse.     

Human myeloma cells shed the interleukin-6 receptor: inhibition by tissue inhibitor of metalloproteinase-3 and a hydroxamate-based metalloproteinase inhibitor

Interleukin-6 (IL-6) is the major growth factor for human myeloma cells, exerting its effect through the IL-6 receptor (IL-6R). A soluble form of IL-6R (sIL-6R) has been identified, which increases the sensitivity of myeloma cells to IL-6. In patients with multiple myeloma (MM), serum concentrations of sIL-6R are elevated and associated with poor prognosis. The present study was undertaken to determine whether proteolytic cleavage of IL-6R could contribute to sIL-6R release from human myeloma cells, and also to identify the class of proteinase responsible for this event. Human myeloma cell lines were shown to express IL-6R upon their surface and also to release sIL-6R into culture supernatants. In addition, phorbol 12-myristate 13-acetate (PMA) stimulated a loss of IL-6R from the cell surface, with a corresponding increase in the concentration of sIL-6R in the supernatant. Inhibitors of serine and cysteine proteinases, and tissue inhibitor of metalloproteinase (TIMP) -1 and TIMP-2, were shown to have no effect on the magnitude of sIL-6R release. In contrast, TIMP-3 and a hydroxamate-based metalloproteinase inhibitor (BB-94), inhibited both constitutive and PMA-induced release of sIL-6R. Myeloma cells freshly isolated from the bone marrow of a patient with MM were also shown to express IL-6R upon their surface, and to shed this receptor in response to PMA. These data demonstrate that increased proteolytic cleavage of IL-6R, mediated by a non-matrix-type metalloproteinase, is likely to contribute to the elevated concentrations of sIL-6R found in the serum of patients with MM. Inhibition of sIL-6R release by hydroxamate-based metalloproteinase inhibitors may represent a novel therapeutic approach to the treatment of MM.     

Soluble interleukin-6 receptors in inflammatory bowel disease: relation to circulating interleukin-6.

The in vivo appearance of soluble interleukin (IL)-6 receptor (sIL-6R) in serum from patients with inflammatory bowel disease was examined using an enzyme linked immunosorbent assay (ELISA). The serum sIL-6R concentrations in patients with active disease (ulcerative colitis, 148.4 (5.1); Crohn's disease, 142.3 (9.3) ng/ml; mean (SEM)) were significantly raised compared with those in patients with inactive disease (ulcerative colitis, 116.2 (7.2); Crohn's disease, 114.3 (7.1) ng/ml), some other type of colitis (104.8 (11.6) ng/ml), or in normal subjects (107.3 (2.4) ng/ml). These differences were also seen in paired samples examined during both active and inactive phases. Additionally, serum sIL-6R and IL-6 concentrations correlated significantly with C-reactive protein levels in both ulcerative colitis and Crohn's disease patients (r = 0.23 and 0.56, respectively; p < 0.05 for both). Furthermore, gel filtration analysis of serum from these patients showed two major peaks of immunoreactive IL-6-one peak corresponding to free IL-6 and another peak to sIL-6R-bound IL-6-this was further confirmed by a luminescence sandwich ELISA. These results, together with its in vitro effects, indicate that natural sIL-6R may function as a powerful enhancer of the IL-6-dependent immune processes observed in inflammatory bowel disease.     

High level of soluble interleukin-2 receptor in serum predicts treatment resistance and poor progression-free survival in multiple myeloma

The IL-2/IL-2 receptor (IL-2R) system plays a central role in maintaining normal T cell immunity, and its disturbance is associated with several hematologic disorders. Studies have found in several types of lymphoma that abnormal amounts of soluble IL-2R (sIL-2R) may result in imbalance of the IL-2/IL-2R system and hence of the T cell immunoregulation. Whether the level of sIL-2R in blood could predict treatment outcomes or not needs to be investigated in multiple myeloma (MM) patients. The level of sIL-2R in serum was measured using enzyme-linked immunosorbent assay (ELISA) in 81 patients with newly diagnosed MM. Twenty-six patients (32.1%) were treated with bortezomib-based regimens and 55patients (67.9%) received old drugs-based regimens. The mean concentration of sIL-2R for myeloma patients was 8.51 ng/ml, significantly higher than that of healthy controls (0.56 ng/ml, p < 0.0001). The best cutoff value for sIL-2R in predicting high risk for disease progression is 6.049 ng/ml with an area under curve (AUC) of 0.665 (p = 0.013). Thirty-six patients (44.4%) were classified as higher sIL-2R level group (> 6.049 ng/ml), and 45 patients (55.6%) as lower group (≤ 6.049 ng/ml). The overall response rate (ORR) was 60.0% in lower sIL-2R level group, and 41.7% in higher level group (p = 0.156). The median progression-free survival (PFS) and overall survival (OS) was 12 months (range, 2.0–65 months) and 20 months (range, 2.0–118 months), respectively. In a multivariate survival analysis, including Eastern Cooperative Oncology Group performance status score, treatment response, and sIL-2R level, it was found that all these three parameters were significantly independent prognostic factors for PFS (p = 0.032, 0.016, and 0.043, respectively), but none factors maintained their value in predicting OS. Subgroup analysis revealed that high level of sIL-2R is correlated with significantly inferior PFS in patients treated with bortezomib-based regimens (p = 0.004). Serum sIL-2R level is an independent prognostic factor for PFS, indicating novel drugs targeting the imbalance of IL-2/IL-2R system may be a promising strategy in MM.     

华支睾吸虫病患者细胞因子水平与肝功能关系的研究

目的　探讨华支睾吸虫病患者细胞因子水平与肝功能的关系。　方法　 47例确诊、但未经药物治疗的华支睾吸虫病患者 ,参照Child Pugh肝功能分级法 ,按照评分将其分成A ( 3～ 4分 ) 2 0例、B( 5～ 6分 ) 15例、C( 7～ 9分 )12例等 3组。用放射免疫法及双抗体夹心酶联免疫吸附测定 (ELISA)法 ,检测血清白细胞介素 2 (IL-2 )、可溶性白细胞介素 2受体 (sIL-2R )、白细胞介素 8(IL-8)、肿瘤坏死因子α(TNF-α) ;用全自动生化分析仪检测患者血清总胆红素(TBL)、血清白蛋白 (ALB)、丙氨酸氨基转移酶 (ALT)。并进行统计分析。　结果　华支睾吸虫病患者sIL-2R、IL-8、TNF-α水平明显高于健康人对照组 (P <0.0 5 ,P <0.0 5 ,P <0.0 1) ,而IL 2含量明显减少 (P <0.0 1)。随着患者肝功能受累程度的加重 ,sIL-2R、IL-8、TNF-α含量依次递增 ,IL-2含量依次递减 ,A组和C组间差异具有显著性意义 (P <0.0 5 )。sIL-2R、TNF α含量与其TBL(r =0.3 3 1　P <0.0 5 ,r =0.5 18　P <0.0 1)及ALT (r =0.475　P <0.0 1,r =0.2 85　P <0.0 5 )呈正相关 ,与ALB呈负相关 (r =-0.3 19　P <0.0 5 ,r =-0.665　P <0.0 1)。　结论　华支睾吸虫病患者细胞免疫功能降低 ,血清IL-2、sIL-2R、TNF-α水平与肝功能状态有一定关系。     

Role of interleukin-18 and T-helper type 1 cytokines in the development of Mycoplasma pneumoniae pneumonia in adults

STUDY OBJECTIVE: Interleukin (IL)-18 is a proinflammatory cytokine, originally termed interferon (IFN)-gamma-inducing factor, which promotes T-helper type 1 (Th1) cytokine responses. We recently reported that serum IL-18 levels were elevated in children with Mycoplasma pneumoniae pneumonia (MP). In this study, we investigated the contribution of IL-18 to the infection and assessed the Th1 cytokine response to pulmonary involvement in adults. METHODS: We investigated the clinical course, pulmonary involvement, and serum levels of IL-18, IFN-gamma, IL-12p40, and soluble IL-2 receptor (sIL-2R) in 21 patients with acute-stage MP and in 21 age- and sex-matched control subjects. RESULTS: Significantly (p < 0.001) increased serum IL-18 (median, 248 pg/mL [range, 89 to 441 pg/mL] vs. median, 126 pg/mL [range, 47 to 217 pg/mL]) and sIL-2R (median, 617 U/mL [range, 410 to 1,032 U/mL] vs. median, 425 U/mL [range, 268 to 601 U/mL]) were found in patients with MP as compared with healthy control subjects, and there was a tendency toward increased serum IFN-gamma and IL-12p40. Circulating IL-18 values had a positive correlation with serum sIL-2R levels (r = 0.62, p = 0.028) and the number of affected pulmonary lobes (sigma = 0.61, p = 0.024), but not with the serum levels of antibodies to M pneumoniae, IFN-gamma, or IL-12p40. Serum IL-18 and sIL-2R values in severe cases were significantly higher (p < 0.03) than those in mild cases. IFN-gamma and sIL-2R levels in four patients with pleural effusion were significantly (p < 0.05) higher than those in the other 17 subjects. CONCLUSIONS: Serum levels of IL-18 were raised during the acute phase of MP. We suggest IL-18 and Th1 cytokines may play a significant role in the immunopathologic responses in MP.     

Mechanisms and pathologic significances in increase in serum interleukin-6 (IL-6) and soluble IL-6 receptor after administration of an anti-IL-6 receptor antibody, tocilizumab, in patients with rheumatoid arthritis and Castleman disease

Interleukin-6 (IL-6) plays pathologic roles in immune-inflammatory diseases such as rheumatoid arthritis (RA) and Castleman disease. By inhibiting IL-6 receptors (IL-6Rs), tocilizumab (a humanized anti-IL-6R antibody) ameliorates the symptoms of these diseases and normalizes acute-phase proteins, including C-reactive protein (CRP). We found that tocilizumab treatment increased serum levels of IL-6 and soluble IL-6R (sIL-6R). To investigate the pathologic significance of these increases, we analyzed the kinetics of serum IL-6 and sIL-6R and the proportion of sIL-6R saturated with tocilizumab after tocilizumab administration in patients with RA and Castleman disease and then compared the results with the CRP values. Serum IL-6 and sIL-6R markedly increased after tocilizumab administration in both RA and Castleman disease. As long as free tocilizumab was detectable, sIL-6R was saturated with tocilizumab and IL-6 signaling was completely inhibited. We concluded that it is likely that sIL-6R increased because its elimination half-life was prolonged by the formation of tocilizumab/sIL-6R immune complex, and that free serum IL-6 increased because IL-6R-mediated consumption of IL-6 was inhibited by the unavailability of tocilizumab-free IL-6R. We also concluded that the increased level of free IL-6 during tocilizumab treatment closely reflects the actual endogenous IL-6 production and true disease activity.     

Serum soluble interleukin-2 receptor measurement in patients with sarcoidosis: a clinical evaluation

OBJECTIVES: To date, insufficient evidence is available to recommend serum soluble interleukin-2 receptor (sIL-2R) measurement as a routine test in the assessment of sarcoidosis. Therefore, we evaluated the clinical value of this test. DESIGN: Forty-seven patients with sarcoidosis, all presenting with active disease, were included in the study. Initial serum sIL-2R levels were determined by enzyme-linked immunosorbent assay, and clinical data at presentation and follow-up were collected retrospectively. RESULTS: The median follow-up period of all patients was 44 months (range, 6 to 100 months), and 38 patients had follow-up data present over at least 24 months. The median sIL-2R level was 1,068 U/mL (range, 248 to 4,410 U/mL; upper limit of normal, 710 U/mL). A positive correlation was found between serum sIL-2R levels and the number of CD4+ T lymphocytes in BAL (rs = 0.53, p < 0.001). In accordance with this result, both sIL-2R level and the number of CD4+ T lymphocytes were elevated in stage I compared to stage III disease (p < 0.05). Patients with extrapulmonary disease (ED) [excluding L?fgren's syndrome] showed higher sIL-2R levels than those presenting with only pulmonary sarcoidosis (p = 0.001). No relation was found between sIL-2R level and response to treatment, and there was no association between sIL-2R levels and radiographic evolution and lung function outcome. CONCLUSIONS: Our data suggest a role for serum sIL-2R as marker of pulmonary disease activity and ED in patients with sarcoidosis.     

Clodronate treatment reduces serum levels of interleukin-6 soluble receptor in Paget's disease of bone

OBJECTIVE: Interleukin-6 (IL-6) and its soluble receptor (sIL-6R) stimulate osteoclast formation and activity. The primary cell abnormality in Paget's disease of bone (PDB) involves osteoclasts. Pagetic osteoclasts overproduce IL-6 and IL-6 receptor in vitro. In vivo, IL-6 serum levels are very high in the acute phase of PDB. The aim of this study was to evaluate the modification in the serum levels of IL-6, sIL-6R and osteotropic hormones (parathormone, 25OHD3 and 1,25(OH)2D3) as a in long-term response to clodronate treatment in patients with PDB. METHODS: 16 patients (8 females) with polyostotic PDB were studied. IL-6, sIL-6R and osteotropic hormones serum levels were evaluated in active PDB and after clodronate treatment (300 mg injected intravenously for 5 consecutive days). The sequential changes in total alkaline phosphatase (tALP) serum levels were used to assess the maximal pharmacological response to treatment. RESULTS: In untreated pagetic patients, mean serum levels of IL-6 (3.20+/-1.18 pg/ml) and sIL-6R (35.02+/-8.33 ng/ml) were significantly increased. Serum osteotropic hormone levels fell within the normal range. Eight weeks after treatment, the maximal pharmacological response to clodronate was associated with a significant reduction of sIL-6R serum levels in all patients, without a significant variation in serum IL-6 and osteotropic hormone levels. Moreover, we observed a correlation between lower sIL-6R serum levels before clodronate therapy and complete remission of PBD, defined as a decrease of tALP serum levels within the normal range. CONCLUSION: The decrease in serum sIL-6R levels could be one of the molecular mechanisms that play a role in the clinical response to clodronate treatment in PDB.     

Interleukin-6 signalling in juvenile idiopathic arthritis is limited by proteolytically cleaved soluble interleukin-6 receptor

OBJECTIVES: Interleukin-6 (IL-6) exerts multiple effects on chondrocytes and fibroblasts within the joint and is associated with disease activity in juvenile idiopathic arthritis (JIA). Although these cells express the ubiquitous signalling receptor for all IL-6-related cytokines, gp130, they do not express a cognate IL-6 receptor. Consequently, IL-6 responses within these cells occur via IL-6 trans-signalling relying on the presence of a soluble receptor (sIL-6R). Levels of sIL-6R in vivo are governed by either proteolytic cleavage (PC) of cognate receptor or by differential sIL-6R mRNA splicing (DS). The aim of this study was to evaluate the contribution of both isoforms to clinical parameters associated with IL-6 signalling in JIA. METHODS: IL-6, sIL-6R and DS-sIL-6R were measured by ELISA in serum and synovial fluid (SF) samples from 86 JIA patients. These data were related to indicators of inflammation-erythrocyte sedimentation rate (ESR) and C-reactive protein (CRP) and compared between patients stratified by subtype, age and disease duration. RESULTS: SF IL-6 significantly correlated with general indicators of activity (ESR and CRP) and SF PC-sIL-6R to a lesser degree with CRP. When the IL-6:sIL-6R ratio was calculated as an indicator of the potential for IL-6 signalling within the joint, 33% of SF samples showed a ratio >1 indicating saturation of sIL-6R by IL-6. Mean DS-sIL-6R levels were 0.71 ng/ml, whereas PC-sIL-6R levels constituted the majority of sIL-6R at 20.89 ng/ml. CONCLUSIONS: IL-6 trans-signalling within the joints of JIA patients is predominantly governed by the presence of PC-sIL-6R, and the data provided suggest that synovial levels of IL-6 and sIL-6R would be sufficient to drive IL-6 responses in chondrocytes and synovial fibroblasts.     

Serum levels of IL-10, IL-6, IL-1ra, and sIL-2R in patients with psoriatic arthritis

Our objective was to evaluate the levels of interleukin-6 (IL-6), soluble receptors of IL-2 (sIL-2R), IL-10, and IL-1 receptor antagonists (IL-1ra) in the serum of patients with psoriatic arthritis (PsA) and to assess the correlation between these levels and parameters of clinical activity of skin and joint disease. In total, 34 patients with PsA and ten healthy volunteers participated in the study. Assessment of joint disease included duration of morning stiffness, number of tender and swollen joints, right and left grip, the presence of inflammatory spinal back pain, and Schober test. Current severity of skin disease was graded according to the psoriasis area and severity index (PASI). Erythrocyte sedimentation rate (ESR) was determined as a marker of disease activity. Serum levels of IL-6, sIL-2R, IL-1ra, and IL-10 were measured by an enzyme immunoassay kit. Significantly higher serum levels of IL-6, sIL-2R, IL-1ra, and IL-10 were found in patients with PsA in comparison with healthy volunteers. A statistically significant correlation was found between levels of sIL-2R and PASI, whereas no association was found with clinical parameters of joint severity. Levels of IL-1ra correlated with the number of tender and swollen joints. No correlation was found between levels of IL-6, IL-10, and clinical parameters of skin and joint severity. In the group of patients with PsA, serum levels of sIL-2R clearly correlated with severity of skin disease, whereas levels of IL-1ra were associated with joint severity. Received: 18 June 1999 / Accepted: 1 October 1999     

Soluble interleukin-6 receptor in rheumatoid arthritis

Abstract

To investigate the pathophysiologic role of soluble interleukin-6 receptor (sIL-6R) in patients with rheumatoid arthritis (RA), serum sIL-6R levels were measured in 15 RA patients and 15 healthy control subjects using a sandwich enzyme-linked immunosorbent assay. Correlation analysis was performed between sIL-6R levels and clinical variables such as joint score, Lansbury’s index, C-reactive protein and platelet counts. Levels of sIL-6R and IL-6 were also measured in paired samples of serum and synovial fluid obtained at the same time from nine RA patients. Serum sIL-6R levels in RA patients (153.9±56.9 ng/ml) were significantly higher than those of control subjects (115.1±19.1 ng/ml; P<0.05). However, sIL-6R levels did not correlate with any clinical characteristic of RA. sIL-6R was detectable in synovial fluid, but was invariably lower than in serum, in contrast to IL-6 (i.e. much higher in synovial fluid). It correlated neither with total cell nor neutrophil number in synovial fluid. Serum C-reactive protein levels were significantly correlated with IL-6 in synovial fluid, but not with sIL-6R in synovial fluid. These results indicate that serum sIL-6R levels are increased in RA patients. High levels of serum sIL-6R did not seem to be derived from the site of local inflammation. The readily detectable sIL-6R in synovial fluid may co-operate with IL-6 in the pathogenesis of synovitis in RA.