Adherence of multiple myeloma cells to bone marrow stromal cells upregulates vascular endothelial growth factor secretion: therapeutic applications.

Increased angiogenesis has recently been recognized in active multiple myeloma (MM). Since vascular endothelial growth factor (VEGF) and basic fibroblast growth factor (bFGF) are two key mediators of angiogenesis, we characterized the production of VEGF, b-FGF and interleukin-6 (IL-6) (a MM growth and survival factor) in MM cell lines and Epstein-Barr virus (EBV) transformed B cell lines from MM patients, patient MM cells, as well as bone marrow stromal cells (BMSCs) from normal healthy donors and MM patients. We detected secretion of VEGF, but no bFGF and IL-6, in MM cell lines (MM.1S, RPMI 8226 and U266); EBV transformed B cell lines from MM patients (IM-9, HS-Sultan and ARH77); MM cell lines resistant to doxorubicin (RPMI-DOX40), mitoxantrone (RPMI-MR20), melphalan (RPMI-LR5) and dexamethasone (MM.1R); and patient MM cells (MM1 and MM2). BMSCs from MM patients and normal donors secreted VEGF, b-FGF and IL-6. Importantly, when MM cells were adhered to BMSCs, there was a significant increase in VEGF (1.5- to 3.1-fold) and IL-6 (1.9- to 56-fold) secretion. In contrast, the bFGF decreased in co-cultures of BMSCs and MM cells. Paraformaldehyde fixation of BMSCs or MM cells prior to adhesion revealed that VEGF was produced both from BMSCs and MM cells, though it may come primarily from BMSCs in some cultures. IL-6 was produced exclusively in BMSCs, rather than MM cells. Moreover, when MM cells were placed in Transwell insert chambers to allow their juxtaposition to BMSCs without cell to cell contact, induction of VEGF and IL-6 secretion persisted, suggesting the importance of humoral factors. Addition of exogenous IL-6 (10 ng/ml) increased VEGF secretion by BMSCs. Conversely, VEGF (100 ng/ml) significantly increased IL-6 secretion by BMSCs. Moreover, anti-human VEGF (1 microg/ml) and anti-human IL-6 (10 microg/ml) neutralizing antibodies reduced IL-6 and VEGF secretion, respectively, in cultures of BMSCs alone and co-cultures of BMSCs and MM cells. Finally, thalidomide (100 microM) and its immunomodulatory analog IMiD1-CC4047 (1 microM) decreased the upregulation of IL-6 and VEGF secretion in cultures of BMSCs, MM cells and co-cultures of BMSCs with MM cells. These data demonstrate the importance of stromal-MM cell interactions in regulating VEGF and IL-6 secretion, and suggest additional mechanisms whereby thalidomide and IMiD1-CC4047 act against MM cells in the BM millieu.

Exogenous and endogenous IL-10 regulate IFN-alpha production by peripheral blood mononuclear cells in response to viral stimulation.

IL-10 is an important regulator of the production of proinflammatory cytokines. Its effect on IFN-alpha production, however, has not been reported. In this study, PBMC from healthy donors were stimulated with virus in the presence of IL-10. Human IL-10 (hIL-10) caused reductions in both the frequency of IFN-alpha-producing cells (IPC) and bulk IFN in response to herpes simplex virus type-1 (HSV-1), Sendai virus, Newcastle disease virus, and vesicular stomatitis virus. The inhibitory effect occurred when IL-10 was added 2 or 4 h before, or 2 h poststimulation with HSV or Sendai virus, but not when added 4 h postinduction. Unlike IL-10, IL-4 did not affect the IFN-alpha response to HSV. However, when PBMC were induced with Sendai virus, IFN-alpha production was also reduced by IL-4. IL-10 treatment of PBMC resulted in strong reductions in the steady state levels of both HSV- and Sendai virus-induced IFN-alpha1, -alpha2, and -beta mRNA as determined by RT-PCR. IFN-alpha production to Sendai virus occurs predominantly by monocytes, whereas most enveloped viruses stimulate low frequency "natural IFN-producing cells (NIPC)," which are thought to be dendritic cells. Peripheral blood dendritic cells were found to express the IL-10 receptor, suggesting that IL-10 may directly act on the dendritic IPC. Addition of monoclonal anti-IL-10 to PBMC resulted in a significant increase in both the frequency of IPC and the amount of secreted IFN-alpha in response to HSV but not Sendai virus. We conclude that human IL-10 can serve as both an endogenous and exogenous regulator of IFN-alpha production.

Transcription of the murine interleukin 5 gene is regulated by multiple promoter elements.

Cis-acting regions in the 5'-flank of the mouse interleukin 5 (IL-5) gene involved in the specific and inducible regulation of IL-5 transcription in an untransformed mouse T cell clone, D10.G4.1, have been identified. Transient transfection assays with a series of deletion IL-5 promoter reporter constructs indicate that multiple regulatory elements in the 5'-flanking region of the IL-5 promoter play a role in regulating IL-5 transcription in Th2 cells. Negatively acting elements, NRE I and NRE II, map to the regions between positions -431 and -392 and positions -300 and -261. A positive regulatory element has been mapped to the region between positions -224 and -81. The activity of these elements is dependent on activation of the cells. A 40-bp sequence within this region, termed the IL-5 PRE, has been shown to bind at least two specific nuclear protein complexes from unstimulated and stimulated D10.G4.1 cells. An additional protein complex specific for this site has been identified in nuclear fractions from cells stimulated in the presence of the protein synthesis inhibitor, cycloheximide. Proteins that bind to these elements are likely to be important inducible and specific factors essential for control of IL-5 transcription in response to T cell receptor-mediated signaling events.

Potential interaction of interleukin-4 with endogenous cytokines in vivo.

We employed alginate-entrapped cells secreting recombinant murine interleukin-4 (IL-4) to study the effect of IL-4 on hematopoietic cells of normal mice. The most dramatic effect was registered in an increase in the neutrophils and to a lesser extent the monocytes. A small increase in the CD4+, CD8+ and B220+ populations was also observed. Serum IgE levels also increased dramatically. All of these increases could be specifically inhibited with anti-IL-4. Antibodies to granulocyte-macrophage colony-stimulating factor, IL-3 and IL-5 could also inhibit some IL-4-mediated actions suggesting an interplay between these cytokines in vivo.

Interleukin-5 modulates eosinophil accumulation in allergic guinea pig lung.

Based on its involvement in eosinophil biology, interleukin 5 (IL-5) may play a role in the pulmonary eosinophilia associated with allergic reactions. We have examined that hypothesis using a neutralizing antibody to IL-5 in ovalbumin-sensitized guinea pigs challenged with aerosolized antigen. The extent of eosinophilia has been quantitated in bronchoalveolar lavage (BAL) and by histologic evaluation of lung tissue sections. Acute intraperitoneal administration of a rat IgG, monoclonal antibody to murine IL-5 derived from TRFK-5 cells prevented lung and BAL eosinophilia in a dose-dependent fashion at and above 10 micrograms per guinea pig. Treatment with either an experimentally irrelevant, isotype-matched antibody from GL113 cells or with heat-denatured IL-5 antibody was without effect. These studies demonstrate the importance of IL-5 to pulmonary eosinophilia in challenged, allergic guinea pigs.

Lower respiratory tract lactoferrin and lysozyme arise primarily in the airways and are elevated in association with chronic bronchitis.

Lactoferrin and lysozyme are proteins found in high concentrations on mucosal surfaces, and they have activities potentially important for the modulation of inflammation. To investigate whether these proteins might contribute to the modulation of the intraluminal airway inflammation associated with chronic bronchitis, lactoferrin and lysozyme were measured in bronchoalveolar lavage (BAL) fluid from 22 subjects with chronic bronchitis and, for comparison, with 10 symptom-free smokers and 16 normal subjects. As a further control, transferrin, a protein structurally homologous to lactoferrin but not known to arise in airway epithelial cells, was also measured. BAL was performed by sequentially instilling and retrieving five 20 ml aliquots of normal saline solution into each of three sites. Analyzing the first aliquots separately from the later four provided fluid that was enriched for airway contents. The concentration of lactoferrin (11.83 +/- 2.86 micrograms/ml vs 0.68 +/- 0.18 micrograms/ml, p less than 0.00001), and lysozyme (6.75 +/- 1.51 micrograms/ml vs 0.52 +/- 0.09 microgram/ml, p less than 0.00001), but not transferrin (3.22 +/- 0.38 microgram/ml vs 2.68 +/- 0.24 micrograms/ml, p = 0.55) was higher in the bronchial sample lavage fluid, suggesting an airway origin for lactoferrin and lysozyme. In subjects with chronic bronchitis, bronchial sample lactoferrin (23.1 +/- 0.5 micrograms/ml) and lysozyme (12.6 +/- 3.5 micrograms/ml) were elevated compared with the normal subjects' lactoferrin (1.9 +/- 0.5 micrograms/ml, p less than 0.0001) and lysozyme (0.77 +/- 0.22 microgram/ml, p less than 0.0001) and the symptom-free smokers' lactoferrin (4.1 +/- 0.8 micrograms/ml, p = 0.005) and lysozyme (4.9 +/- 1.3 micrograms/ml, p = 0.02). Transferrin concentrations did not demonstrate the same relationships. Finally, when the content of bronchial sample lactoferrin and lysozyme were compared with the content of bronchial sample neutrophils, poor correlations were found, which may imply an airway epithelial origin for the two proteins. Thus lactoferrin and lysozyme appear to arise in the lower respiratory tract within the airways and their levels are elevated in association with chronic bronchitis. This suggests that lactoferrin and lysozyme may contribute to the modulation of airway inflammation in chronic bronchitis.

Monoclonal antibodies for coagglutination of Streptococcus suis type 1.

Monoclonal antibodies (MAbs) were sought that would identify Streptococcus suis. Spleen cells from Balb/c mice immunized with formalin-killed S. suis were fused with the murine cell-line SP-2/0. Hybridomas positive for S. suis were identified by a solid-phase radioimmunoassay with a mixture of all available serotypes of S. suis. On further screening with individual serotypes of S. suis (Types 1, 2, 1/2, 3, 4, 5, 7, 8, 9 and 12) and other related and unrelated bacteria, a hybridoma specific for Type 1 was identified. Another hybridoma was positive for all serotypes of S. suis. S. suis Type 1-specific MAbs in the form of ascites fluid was used in coagglutination test. Agglutination with S. suis Type 1 was observed within 45 s, while there was no reaction with other serotypes of S. suis or other bacteria, during the 5-min observation period. A library of type-specific MAbs should help in rapid and accurate serotyping of S. suis isolates.