The soluble human interleukin-6 receptor (shIL6R) was purified from human plasma. In a single immunoaffinity purification step a 140000-fold enrichment with a yield of 95% was achieved. A subsequent IL-6 affinity chromatography resulted in a homogeneous receptor preparation but only in a yield of less than 5%. The biological activity of the soluble receptor was clearly demonstrated by its ability to induce the synthesis of the acute-phase protein a, -antichymotrypsin in HepG2 cells stably transfected with IL-6. Upon gel filtration, the native shIL6R showed an apparent molecular mass of 93 kDa. Analysis by SDSPAGE revealed an apparent molecular mass of 65 kDa for the soluble receptor. Deglycosylation with peptide N-glycosidase F led to a shift in molecular mass from 65 kDa to 45 kDa. It has previously been shown that the shIL6R can be generated by shedding the membrane-bound form or by expression of an alternatively spliced mRNA. Here we show that the shIL6R isolated from human plasma is recognized by an affinity-purified peptide antibody raised against an amino acid sequence unique for the alternatively spliced isoform. Thus, the shIL6R isoform generated through alternative splicing which has been previously detected in supernatants of cultured cell lines is also an in vivo product circulating in human plasma.

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Manidipine, a Ca2+-channel blocker, at concentrations that lower elevated blood pressure, modulates the transcription rates of cytokine genes in the mesangial cells of humans that had been stimulated with platelet-derived growth factor BB isomer; although the transcription for mRNA of interleukin 1p3 and granulocyte/monocyte colony-stimulating factor was inhibited, the transcription of mRNA for interleukin 6 was enhanced. Additionally, the induction of c-fos, c-jun, and 3-hydroxy-3-methylglutaryl-coenzyme A reductase transcription was inhibited by manidipine. We conclude that manidipine, at nanomolar concentrations, is efficacious in modulating gene transcriptions that are involved in proinflammatory changes of mesangial cells. Thus, manidipine, at pharmacological concentrations that are one to two orders of magnitude lower than those required for inhibition of agonist-or depolarization (K+)-induced vasoconstriction, causes changes in the activity of the genes that code for inflammatory mediators.

Background -Broncho-Vaxom (OM-85 BV) increases the resistance of the respiratory tract to bacterial infections by modulating host immune responses. The compound increases serum IgG levels but decreases IgE levels in patients suffering from chronic bronchitis or chronic obstructive pulmonary disease. It increases concentrations of y-interferon (IFN-y),

Soluble receptors for several cytokines have been detected in body fluids and are believed to modulate the cytokine response by binding the ligand and thereby reducing its bioavailability. In the case of IL-6, the situation is more complex. The receptor consists of two components, including a ligand-binding α-subunit (IL-6R, gp80, or CD126), which in its soluble (s) form (sIL-6R) acts agonistically by making the ligand accessible to the second subunit, the signal transducer gp130 (CD130). Soluble forms of both receptor subunits are present in human blood. Gel filtration of iodinated IL-6 that had been incubated with human serum revealed that IL-6 is partially trapped in IL-6/sIL-6R/sgp130 ternary complexes. sgp130 from human plasma was enriched by immunoaffinity chromatography and identified as a 100-kDa protein. Functionally equivalent rsgp130 was produced in baculovirus-infected insect cells to study its antagonistic potential on four different cell types. It was found that in situations in which cells lacking membrane-bound IL-6R were stimulated with IL-6/sIL-6R complexes, sgp130 was a much more potent antagonist than it was on IL-6R-positive cells stimulated with IL-6 alone. In the latter case, the neutralizing activity of sgp130 could be markedly enhanced by addition of sIL-6R. As a consequence of these findings, sIL-6R of human plasma must be regarded as an antagonistic molecule that enhances the inhibitory activity of sgp130. Furthermore, in combination with sIL-6R, sgp130 is a promising candidate for the development of IL-6 antagonists.