Inhibitory effect of all-trans retinoic acid on the growth of freshly isolated myeloma cells via interference with interleukin-6 signal transduction [see comments]

We showed the dose-dependent growth inhibition by alltrans retinoic acid (ATRA) of myeloma cells freshly isolated from patients. ATRA downregulated the cell surface expression of interleukin-6 receptor (IL- 6R) and/or glycoprotein (gp) 130. The growth-inhibitory activity of ATRA was well correlated with that of anti-gp 130 antibody in every sample. Furthermore, ATRA inhibited the production of IL-6 from both myeloma cells and marrow stromal cells, and recombinant IL-6 (rIL-6) could partially recover the myeloma cell growth that had been inhibited by ATRA. These data suggest that ATRA may inhibit the proliferation of myeloma cells both by the downregulation of IL-6R and gp130 expression on myeloma cells and by the inhibition of IL-6 production from myeloma and stromal cells. Prednisolone (PSL) and interferon-gamma (IFN-gamma) also inhibited the myeloma growth, while their effects were different from those of ATRA on IL-6 R and gp130 expression, IL-6 production, and morphological change. The inhibitory effect of ATRA on myeloma cell proliferation was observed in 10 of 14 samples obtained from eight patients, which suggests that ATRA may be a potent new therapeutic agent for some myeloma patients.     

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.     

Diagnostic value of serum IL-6 level in monoclonal gammopathies

Summary. The serum level of IL-6 was reported to reflect disease severity in patients with multiple myeloma. We used a specific radioimmunoassay to measure the level of IL-6 in 239 serum samples in which a monoclonal gammopathy was identified for the first time. The same sample was used for the measurement of serum C reactive protein and serum albumin. Then, an inventory of clinical and biological features allowed us to classify these patients into five groups: monoclonal gammopathy of undetermined significance (MGUS: 128), multiple myeloma (MM:66), Waldenström's macroglobulinaemia (WM:27), non-Hodgkin's lymphoma (NHL: 11) and chronic lymphocytic leukaemia (CLL: 7). The number of patients with serum IL-6 (S-IL-6) level >0.335 ng/ml (upper limit in normal sera) was significantly higher in the MM group (35%; Confidence Interval (CI) 23.5–46.5) compared with the MGUS group (15%; CI 8.8–21.2). The distribution of S-IL-6 levels was also significantly different between the groups (Mann-Whitney test: P< 0.01). High S-IL-6 levels were measured in 5/11 patients with NHL and 9/27 patients with WM. The distribution of S-IL-6 levels in these groups was the same as that in MGUS or MM groups. In patients with MM, elevated S-IL-6 levels were associated with haemoglobin level <100 g/l (P< 0.005). bone marrow plasmocytosis >50% (P<0.05) and stages II and III in the Durie & Salmon staging system (P< 0.005). The S-IL-6 level was also related to light chain component excretion in urine (P<0.01) and M component serum level for IgA (P<0.01). In patients with MGUS, the S-IL-6 level correlated with serum CRP level (P<0.05). serum lactate dehydrogenase (P< 0.05) and serum ferritin (P < 0.01). We conclude that the S-IL-6 level is a marker of high tumour burden in multiple myeloma. However, S-IL-6 level can be increased in patients with MGUS in relation to inflammatory parameters. Therefore the S-IL-6 level does not demonstrate high predictive value for the diagnosis of MM in patients with newly identified monoclonal gammopathy.     

Dexamethasone plus retinoids decrease IL-6/IL-6 receptor and induce apoptosis in myeloma cells

Interleukin 6 (IL-6) is the most important known growth factor for multiple myeloma, and IL-6 signalling pathways are potential targets for therapy. We hypothesized that interfering with the IL-6 signalling pathway at more than one level would be more effective than a single block in inhibiting proliferation of myeloma cells. Accumulating data support the concept that glucocorticoids down-regulate IL-6, whereas retinoic acid derivatives (RA) down-regulate IL-6R in myeloma. We found that all- trans RA (ATRA), 13- cis -RA and 9- cis -RA each similarly inhibited growth of RPMI 8226 myeloma cells and that addition of dexamethasone (DEX) added to RA growth inhibition. The major effects of retinoids were to reduce the proliferative fraction and induce apoptosis whereas DEX increased the apoptotic fraction. When combined, apoptosis was enhanced. Effects of RA + DEX were also least able to be overcome by exogenous IL-6. RA decreased IL-6R levels and addition of DEX to RA delayed recovery of IL-6R levels compared with RA alone. Since RPMI 8226 cells have undetectable IL-6, we investigated U266B1 cells and found that RA and DEX decreased both IL-6 secretion and IL-6 RNA levels. Mechanistically, IL-6R down-regulation by RA was enhanced by DEX, whereas IL-6 protein and RNA levels were reduced by DEX and by RA. In summary, combinations of RA + DEX were not only more effective in inhibiting myeloma cells growth by the dual mechanisms of decreasing proliferative fraction and increasing apoptotic fraction, but were also less able to be overcome by IL-6.     

Malignancy: Identification of Predictors of Disease Status and Progression in Patients with Myeloma (MM)

Multiple studies have attempted to recognize the best markers of disease activity and outcome in myeloma (MM). Our objective was to identify the best variables that can reflect MM disease status. Design and methods: The data obtained from all the following tests were included in the analysis: serum levels of the 2 growth factors known to be crucial for MM growth (i.e. IL-6, and sIL-6R), routine peripheral blood data (Hb%, serum calcium, albumin, CRP, B2m, LDH) and bone marrow plasma cell (BMPC)%, as well as the age and sex of patients. The study was conducted on 21 cases of MM under chemotherapy (aged 48-74 years; M/F = 13/8) and 12 matched normal individuals. The patients were categorized into 2 groups according to their clinical status: Group#1 (n = 16; cases in plateau/stable phase), and Group#2 (n = 5; advanced/refractory cases). Results: Student t-test confirms that serum IL-6 and sIL-6R are the most statistically different variables upon comparing cases in plateau phase (Group#1) with those of advanced disease (Group#2). Stepwise discriminant analysis of data has resulted in a function that is composed of the 2 most salient variables (i.e. serum IL-6, sIL-6R). The proposed function was highly significant (p = 0.0000) with Wilk's Lambda = 0.02538. The diagnostic capability of the proposed function was very high (percent of grouped cases that were classified correctly= 100%). Conclusion: measurement of serum IL-6 and sIL-6R gives the best prediction of disease activity in patients with MM.     

IL-6-induced activation of MYC is responsible for the down-regulation of CD33 expression in CD33(+) myeloma cells

Human myeloma cells from about 10% of cases with multiple myeloma expressed CD33 and had monocytoid morphology with convoluted nuclei, and all these patients had no increase in serum CRP values. In CD33(+) myeloma cells as well as myeloma cell lines, CD33 expression levels were correlated with the increased expression levels of CEBPA (C/EBPα). This correlation was confirmed by the finding that transfection with the CEBPA gene induced CD33 expression in a CD33(−) myeloma cell line. As suggested by the lack of an increase in serum CRP values in CD33(+) myelomas, IL-6 down-regulated the expression of CD33 in CD33(+) myeloma cell lines along with the down-regulation of CEBPA gene expression. Cucurbitacin I (STAT3 inhibitor), but not U0126 (MAPK inhibitor), could abolish the effect of IL-6. Furthermore, IL-6 up-regulated the expression of MYC via STAT3 phosphorylation and MYC bound to the promoter region of the CEBPA gene followed by the down-regulation of CEBPA expression. It was confirmed that introduction of shRNA for MYC into a CD33(+) myeloma cell line blocked the IL-6-induced down-regulation of CD33 and CEBPA expression. Therefore, these results indicate that IL-6 can reverse the expression level of CD33 by up-regulating MYC followed by the down-regulation of CEBPA expression.     

Serum levels of interleukin-6 in multiple myeloma and other hematological disorders: correlation with disease activity and other prognostic parameters

Summary Interleukin-6 (IL-6) is a multifunctional cytokine involved in the regulation of the terminal differentiation pathway of B lymphocytes. Recent reports revealed its potential role in the in vitro and in vivo growth of human multiple myeloma cells. The mechanism, however, by which IL-6 triggers proliferation of malignant plasma cells remains controversial. Using the very sensitive 7TD1 bioassay we quantified endogenous circulating IL-6 levels in serum samples of 104 patients suffering from monoclonal gammopathies and other hematological disorders [47 with multiple myeloma (MM), 24 with monoclonal gammopathy of unknown significance (MGUS), 8 with myeloproliferative disease, and 25 suffering from lowgrade non-Hodgkin's lymphoma (NHL)]. Elevated serum levels of IL-6 (>5 pg/ml) were detected in 42% of the patients with MM, in 13% with MGUS, in 15% with low-grade B-NHL, and in 1 patient with T-NHL. In patients suffering from chronic myeloproliferative diseases, IL-6 levels were within the normal range. In patients with myeloma, IL-6 levels were significantly higher at advanced stages (II/III) or with progressive disease than in patients with MM stage I, MGUS, or at the plateau phase (P<0.01). In patients with monoclonal gammopathies including MGUS, serum IL-6 levels correlated with neopterin, tumor necrosis factor alpha and ₂-microglobulin. An inverse correlation was found with hemoglobin levels. From these results, we propose that in myeloma patients serum IL-6 levels may reflect disease activity and tumor cell mass. The correlation with serum neopterin, a macrophage product, also suggests its origin in an activated immune system.     

Cytomorphology and proliferating cell nuclear antigen in myeloma plasma cells correlate with serum Il-6 and sIl-6R concentrations in multiple myeloma

Background: Proliferating cell nuclear antigen (PCNA), a cofactor for δDNA-dependent DNA polymerase, is an indicator of the proliferative state of the cell. Il-6 and sIl-6R are known to be growth factors for human myeloma cells. The study was aimed at testing the correlations between cytomorphology and PCNA expression in myeloma plasma cells, as well as serum Il-6 and sIl-6R concentrations in 36 patients in an advanced stage of the disease. Methods: PCNA was determined and either lambda or kappa light chain double staining of multiple myeloma (MM) plasma cells was performed. Il-6 and sIl-6R serum concentrations were assessed with the ELISA method. Results: PCNA-positive cells ranged from 5% to 100%; higher PCNA expression was observed in patients with immature plasma cells (mean=28.8%, S.D.=3.2), the highest in MM with plasmablasts in bone marrow (mean=57.2%, S.D.=28.0). Serum Il-6 and sIl-6R levels were higher in the plasmablastic type of MM than in mature ones (P=0.02 and P=0.01, respectively). Elevated PCNA expression and increased serum Il-6 and sIl-6R levels were present in patients with hyperviscosity coma as well as in patients with renal failure. Conclusions: PCNA expression in myeloma plasma cells indicates the myeloma's proliferative activity and correlates positively with serum Il-6 and sIl-6R concentrations, especially in advanced stages of the disease.     

Serum interleukin-6 has no discriminatory role in paraproteinaemia nor a prognostic role in multiple myeloma.

We determined interleukin-6 (IL-6) levels in the serum of 212 well-defined patients with newly diagnosed paraproteinaemia and evaluated its discriminatory value and prognostic role in multiple myeloma (MM). Results were compared with serum neural cell adhesion molecule and beta-2-microglobulin, both established prognostic MM markers. Paraproteinaemia-related diagnoses were: MM (60), other haematological diseases (46), solid tumours (35), autoimmune diseases (17) and monoclonal gammopathy of unknown significance (MGUS) (54). The range of IL-6 levels in all diagnostic groups overlapped widely and did not serve as a discriminatory marker in newly diagnosed paraproteinaemia even when patients with infection or fever (42) were excluded. In MM high IL-6 levels (>/= 50 pg/ml) were not associated with a shorter survival (P = 0.24). We compared our results with 20 published studies on serum IL-6 in paraproteinaemia and/or MM. IL-6 data have to be related to the assay used (bio- or immunoassay) and to the status of MM (newly diagnosed, during therapy, progressive disease). We conclude that serum IL-6 is not specific for paraproteinaemia-related diseases and will not serve as a reliable discriminatory or prognostic marker in paraproteinaemia and MM.     

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.     

Serum interleukin-10 in plasma-cell dyscrasias

Serum levels of interleukin-10 (IL-10) were measured by enzyme-linked immunosorbent assay in 115 patients with multiple myeloma (MM) in various phases of the disease (68 at diagnosis, 22 in plateau phase, 22 in relapse), in 71 individuals with monoclonal gammopathy of undetermined significance (MGUS), and in 53 normal volunteers. Detectable levels of serum IL-10 were found in 24 myelomas (20.9%), in 7 cases of MGUS (9.9%), and in 4 normal subjects (7.5%) (P = NS, χ² test). In patients with MM, cytokine was detected with a comparable frequency in all pathologic stages and phases of the disease: 4/19 in stage I, 6/26 in stage II, 5/23 in stage III, 4/22 in plateau phase, and 5/25 in progressing or relapsed disease. IL-10 concentrations did not differ significantly between controls and patients with plasma-cell dyscrasia, between patients with MGUS and those with MM, between early vs. advanced MM, or between patients in different phases of the disease. In 36 patients with MM in whom IL-10 was measured serially, no significant changes were observed over the course of the disease. Also, when comparing the outcomes of individuals with detectable or undetectable IL-10 in single stages or in the whole myeloma group, no differences were revealed. Our results do not support an apparent involvement of IL-10 in the pathogenesis of MM in vivo. However, further studies are required to define the exact role of this cytokine within the complex cytokine network of this neoplastic disorder. Am. J. Hematol. 54:335–337, 1997. © 1997 Wiley-Liss, Inc.     

Do baseline Cereblon gene expression and IL‐6 receptor expression determine the response to thalidomide–dexamethasone treatment in Multiple myeloma patients?

Immunomodulatory drugs (IMiDs) are key components of treatment for hematologic malignancies, especially multiple myeloma (MM). Cereblon (CRBN) expression was described to be essential for the activity of thalidomide. Furthermore, IMiD binding to CRBN is cytotoxic to multiple myeloma cells and absence of CRBN confers IMiDs resistance. Interleukin‐6 (IL‐6) is a potent pleiotropic cytokine that regulates plasma cell (PC) growth via the IL‐6 receptor (IL‐6R). IL‐6/IL‐6R autocrine activity is implicated in the development and progression of cancers including cervical cancer, prostate cancer, and multiple myeloma. The aim of the study was to evaluate CRBN and IL‐6R expressions and their impact on clinical efficacy of dexamethasone–thalidomide therapy in multiple myeloma (MM) patients, in addition to their association with other clinical and prognostic parameters. Forty‐six newly diagnosed MM patients were enrolled in the study. We measured CRBN expression prior to therapy initiation by real‐time polymerase chain reaction in 46 bone marrow (BM) aspiration samples of patients and controls. In addition, IL‐6R expression was evaluated on BM biopsies of patients and controls by immunohistochemistry (IHC). Twenty‐eight males (60.9%) and 18 females (39.1%) were enrolled. The mean age was 65.11 ± 7.3 yr (range 39–77 yr). Median CRBN expression in 46 BM samples of MM patients was significantly higher than in controls (P < 0.001). Among established prognostic parameters, international staging system (ISS), serum beta‐2‐microglobulin (B2M), and serum albumin correlated reversely with CRBN expression. IL‐6R expression was significantly higher in patients than in controls. IL‐6R expression was significantly associated with response to treatment (P < 0.001), B2M (P = 0.032), and ISS (P = 0.028). Strong intensity expression was associated with low CRBN expression (P   =   0.001).In conclusion, CRBN expression may provide a biomarker to predict response to IMiD in patients with MM and its high expression can serve as a marker of good prognosis. Strong IL‐6R expression is associated with poor response to therapy in multiple myeloma patients and may be used as a prognostic marker.     

High levels of interleukin-6 are associated with low tumor burden and low growth fraction in multiple myeloma

Interleukin-6 (IL-6) is a multifunctional cytokine postulated to play a central role as a growth factor for multiple myeloma (MM). We evaluated the spontaneous secretion of IL-6 in supernatants of Ficoll-Hypaque-- enriched bone marrow (BM) cultures from 35 patients with MM. The levels of IL-6 were correlated with biological and clinical characteristics of the disease. High levels of IL-6 production defined a subgroup of patients with low tumor burden as determined by lower serum beta 2- microglobulin (B2M) (P = .02) and lower percentage of myeloma cells infiltrating the bone marrow (P = .003), higher synthetic rates of monoclonal protein (P = .006), and low proliferative compartments as measured by the percentage of Ki-67--positive myeloma cells. Patients with high proliferative fractions (Ki-67--positive myeloma cells > 20%) had significantly lower levels of IL-6 when compared with patients with low proliferative fractions (P = .005). Our findings do not support IL- 6 as a major growth factor for MM, but demonstrate an association of high levels of IL-6 secretion with low tumor cell burden and low proliferative fraction.     

Interleukin-10 is a proliferation factor but not a differentiation factor for human myeloma cells

Because interleukin-10 (IL-10) is a potent differentiation factor of human B cells into mature plasma cells, we investigated its effect on human malignant plasma cells. IL-10 did not induce any differentiation and increase in Ig synthesis in four human IL-6-dependent malignant plasma cell lines. However, it stimulated the proliferation of two of four cytokine-dependent cell lines in the absence of IL-6 and IL-10- dependent myeloma cell lines have been obtained. The myeloma cell growth activity of IL-10 was unaffected by anti-IL-6 and anti-IL-6R antibodies. Similarly, IL-10 stimulated (P = .001) the proliferation of freshly-explanted myeloma cells in IL-6-deprived cultures of tumor samples from patients with active multiple myeloma (MM) and produced twice as many myeloma cells in these cultures. Again, this cytokine was unable to induce further differentiation (assessed by rate of Ig production) of fresh myeloma cells. A very sensitive enzyme-linked immunosorbent assay (ELISA; 1 pg/mL) only rarely detected IL-10 in the sera of MM patients (3 of 89). On the contrary, serum IL-10 was detected in 60% of patients with plasma cell leukemia (12 of 20). These data show that IL-10 is an IL-6-unrelated growth factor for malignant plasmablastic cells. This cytokine could be involved in the late phase of MM in vivo.     

Clinical significance of sCD105 in angiogenesis and disease activity in multiple myeloma

BackgroundΤhe importance of angiogenesis in malignancies' growth is well recognized. CD105 (Endoglin), a proliferation-associated glycoprotein, is a powerful marker of neovascularization. Elevated amounts of solubleCD105 (sCD105) have been identified in selected solid tumors. The aim of the study was to estimate circulating levels of sCD105 and soluble transforming growth factor-β₁ (sTGF-β₁), in multiple myeloma (MM) patients, to determine their significance in tumor progression and to investigate the correlation between sCD105 and markers of disease activity.MethodsWe studied 50 newly diagnosed MM patients. Twenty-five of them were also investigated in plateauphase. Twenty patients with monoclonal gammopathy of undetermined significance (MGUS) were enrolled in this study. As control group 28 healthy persons were studied. We determined sCD105, sTGF-β₁ and interleukin-6 (IL-6) in the serum, Ki-67 proliferation index (Ki-67 PI) expression and microvascular density(MVD) in bone marrow with immunohistochemistry.ResultsThe mean concentrations of sCD105 and IL-6 were higher in MM and MGUS patients compared to controls, whereas serum levels of sTGF-β₁ were lower in MM patients compared to MGUS patients and controls. sCD105 levels, were significantly different among disease stages, with higher values in advanced stages. It was found that sCD105 correlated with Ki-67 PI, MVD and IL-6.ConclusionsCD105 seems to play an important role in angiogenesis and tumor progression. Circulating levelsof sCD105 could detect patients with more advanced disease and might help in evaluating the response to treatment.     

Serum interleukin-6 (IL-6) and interleukin-4 (IL-4) in patients with multiple myeloma (MM)

In this study we determined, in patients with multiple myeloma (MM), serum levels of IL-4 and IL-6 at diagnosis and during the course of the disease, seeking a correlation with disease activity and prognosis. We studied 54 MM patients, 41 of whom responded to chemotherapy whilst 11 were resistant. At diagnosis, IL-6 was increased in 66% of patients (median 35.5 pg/ml) whereas IL-4 was low (median 4 pg/ml) in 75% of patients. In responding patients, IL-4 increased in remission (median 25 pg/ml), whereas IL-6 decreased (median 4 pg/ml). In chemotherapy-resistant patients, IL-6 and IL-4 values remained stable during the course of the disease.     

Elevated serum concentration of hepatocyte growth factor in patients with multiple myeloma: correlation with markers of disease activity

Hepatocyte growth factor (HGF) has been shown to be involved in angiogenesis, epithelial cell proliferation, and osteoclast activation. HGF and its receptor are expressed on myeloma cell lines and could be involved in the pathogenesis of bone destruction in multiple myeloma (MM). The aim of this study was to examine serum levels of HGF in untreated MM patients and its correlation with bone turnover indices and markers of disease activity. Forty-seven newly diagnosed MM patients and 25 controls were included: 12 patients were of stage I, 13 of stage II, and 22 of stage III (Durie-Salmon classification). Bone lesions were scored from 0 to 3, according to X-ray findings. Serum osteocalcin (OC), interleukin-6 (IL-6), TNF-alpha, beta(2)-microglobulin (beta(2)M), CRP, calcium, and 24-hr urine N-telopeptide cross-links of collagen breakdown (NTx) were determined. HGF levels were significantly higher at stage III compared to stages II and I (medians: 1,990.4 vs. 1,743.8 and 1,432.4 pg/mL, respectively, P < 0.05). Similarly, NTx, IL-6, TNF-alpha, CRP, beta(2)M, and calcium increased significantly with advancing stage (P < 0.01). OC was higher at stage I in comparison to stages II and III (P < 0.01). All parameters were significantly higher in patients than controls. HGF showed a strong correlation with IL-6 and TNF-alpha and less with beta(2)M, CRP, NTx, and OC. We conclude that serum HGF levels are increased in advanced stages of MM disease and extended bone lesions. HGF correlates with IL-6 and TNF-alpha, which are cytokines involved in osteoclast stimulation in MM. However, an independent association of HGF with bone turnover markers was not shown in this study, thus its role in MM bone disease needs to be further clarified.     

Circulating levels of interleukin-6, its soluble receptor and interleukin-6/interleukin-6 receptor complexes in patients with type 2 diabetes mellitus

We evaluated the relationship between plasma fibrinogen concentration and the serum levels of interleukin-6 (IL-6), its soluble receptor, and their complex in patients with type 2 diabetes mellitus. The study comprised 57 patients with type 2 diabetes and 15 normal healthy controls. Serum levels of IL-6, soluble IL-6 receptor (IL-6R), and circulating IL-6/IL-6R complex were determined by enzyme-linked immunosorbent assays. Correlations between the different study parameters and serum IL-6, IL-6R, or IL-6/IL-6R complex levels were determined by multiple linear regression analysis. Any association between the different study parameters and the serum levels of IL-6, IL-6R, or IL-6/IL-6R complex were determined by stepwise linear regression analysis. The serum IL-6 level in diabetic subjects was significantly higher than in normal healthy controls (3.48 ± 3.29 pg/ml vs 0.784 ± 0.90 pg/ml, mean ± SD, respectively, P = 0.0001). The specific optical density of the serum IL-6/IL-6R complex in diabetic patients was also significantly higher than in normal healthy controls, although there was no significant difference in the serum IL-6R level between diabetic patients and controls. The serum IL-6 concentration was correlated significantly with the HbA_1C level (β = 0.58, P = 0.04) by multiple regression analysis. Stepwise regression analysis revealed that the levels of serum IL-6 (F = 8.251), HbA_1C (F = 1.08), and serum urea nitrogen (F = 5.603) were associated with the plasma fibrino gen concentration. These results suggest that hyperglycaemia and increased levels of serum IL-6 can increase the plasma fibrinogen concentration, one of the known risk factors for atherosclerosis in patients with type 2 diabetes mellitus. Received: 24 August 1998 / Accepted in revised form: 2 February 1999