Extramedullary Expansion of Hematopoietic Progenitor Cells in Interleukin (IL)-6–sIL-6R Double Transgenic Mice

Soluble cytokine receptors modulate the activity of their cognate ligands. Interleukin (IL)-6 in association with the soluble IL-6 receptor (sIL-6R) can activate cells expressing the gp130 signal transducer lacking the specific IL-6R. To investigate the function of the IL-6–sIL-6R complex in vivo and to discriminate the function of the IL-6–sIL-6R complex from the function of IL-6 alone, we have established a transgenic mouse model. Double-transgenic mice coexpressing IL-6 and sIL-6R were generated and compared with IL-6 and sIL-6R single-transgenic mice. The main phenotype found in IL-6–sIL-6R mice was a dramatic increase of extramedullary hematopoietic progenitor cells in liver and spleen…

Liver regeneration induced by a designer human IL‐6/ sIL‐6R fusion protein reverses severe hepatocellular injury

The cytokine IL-6 plays a significant role in liver regeneration in conjunction with additional growth factors (HGF, TNF-α, and TGF-α). Many IL-6 effects depend on a naturally occurring soluble IL-6 receptor (sIL-6R). Here, the chimeric protein hyper-IL-6, constructed from the human IL-6 protein fused to a truncated form of its receptor, was found to have superagonistic IL-6 properties, and as such, enhanced liver cell regeneration. Hyper-IL-6 reversed the state of hepatotoxicity and enhanced the survival rates of rats suffering from fulminant hepatic failure after D-galactosamine administration. The hyper-IL-6 protein has a significant potential for use in the treatment of severe human liv…

The designer cytokine hyper-IL-6 mediates growth inhibition and GM-CSF-dependent rejection of B16 melanoma cells.

The low immunogenic B16 melanoma cell line was transfected with a mammalian expression vector containing the complementary DNA for a sIL-6R/IL-6 fusion protein, termed Hyper-IL-6 (H-IL-6), which was shown to have biological activities at 100-1000-fold lower concentrations than IL-6 in combination with sIL-6R. The secreted p84 glycoprotein was detected in the supernatant of transfected cells and was fully active on BAF3/gp130 cells, which respond to IL-6/sIL-6R but not to IL-6 alone. Administration of recombinant H-IL-6 to C57BL/6 mice resulted in a prolonged acute phase protein gene expression indicating long systemic persistence of the fusion protein. Transfected B16 cells (B16/H-IL6 cells…

Acute hepatic failure: limitations of medical treatment and indications for liver transplantation.

The function of the soluble IL-6 receptor in vivo.

Interleukin-6 (IL-6) is considered an important mediator of acute inflammatory responses. Moreover, IL-6 functions as a differentiation and growth factor of hematopoietic precursor cells, B-cells, T-cells, keratinocytes, neuronal cells, osteoclasts and endothelial cells. IL-6 exhibits its action via a receptor complex consisting of a specific IL-6 receptor (IL-6R) and a signal-transducing subunit (gp130). Soluble forms of both receptor components are generated by shedding and are found in patients with various diseases such as AIDS, rheumatoid arthritis and others. The function of the soluble IL-6R in vivo is unknown. To discriminate between the biologic function of hIL-6 alone and that of …

Yeast expression of the cytokine receptor domain of the soluble interleukin-6 receptor

Abstract The complex of the soluble interleukin-6 receptor (sIL-6R) and IL-6 (IL-6) is a potent agonist on cells expressing the signal transducing protein gp130. In contrast, IL-6 alone only stimulates cells which express a membrane bound form of the IL-6R and gp130. The natural occurring sIL-6R is generated by shedding of the membrane receptor and to a lesser extend by alternative splicing. We have inserted the coding sequence of the 323 amino acid residues of the human sIL-6R into an expression/secretion vector suitable for the methylotrophic yeast Pichia pastoris . We obtained, however, no detectable expression and secretion of the recombinant protein. When we used only the coding sequen…

Astrocytic alterations in interleukin-6/Soluble interleukin-6 receptor alpha double-transgenic mice.

Interleukin-6 (IL-6), a major cytokine with diverse effects on cells mainly of the immune and hematopoietic systems, has been linked to several neurological disorders such as acquired immune deficiency syndrome dementia, multiple sclerosis, and Alzheimer's disease. Central nervous system (CNS)-specific expression of IL-6 caused neurodegeneration, massive gliosis, and vascular proliferation in transgenic mice. However, the effects of systemically circulating IL-6 and its receptor IL-6Ralpha on the CNS are unknown. IL-6Ralpha is the specific component of the IL-6 receptor system and hence an important co-factor of IL-6. IL-6Ralpha is bioactive in a membrane-bound and in a soluble (s) form. We…

Randomised trial of mycophenolate mofetil versus azathioprine for treatment of chronic active Crohn’s disease

BACKGROUNDCrohn’s disease is a chronic inflammatory disease of the alimentary tract. Azathioprine is an effective agent in the management of chronic active Crohn’s disease leading to long term remission of disease activity. Such treatment leads to limited efficacy or side effects in a small subset of patients.AIMSTo compare efficacy and side effects of treatment with azathioprine plus corticosteroids versus mycophenolate mofetil (MMF) plus corticosteroids in patients with chronic active Crohn’s disease.METHODSSeventy patients with chronic active Crohn’s disease (Crohn’s disease activity index (CDAI) greater than 150) were randomised for treatment with azathioprine/cortisone or MMF/cortisone…

Possible role of human interleukin-6 and soluble interleukin-6 receptor in hepatitis B virus infection

Human interleukin-6 has been shown to promote hepatitis B virus (HBV) infection. However, it is not clear whether this influence is the result of a direct interaction between interleukin-6 (IL-6) and the HBV envelope proteins or of a rather indirect mechanism. A direct interaction of IL-6 and the preS region of the large envelope protein (L-protein) of HBV has been reported. In this study we assessed the binding of IL-6 and of the IL-6 receptor subunits to the preS region of the L-protein of HBV. Binding of IL-6 and IL-6 receptor subunits sIL-6R and gp130 to preS was assessed by immunoprecipitation with recombinant preS proteins. In patient sera IL-6 and sIL-6R concentrations were analysed …

The function of the soluble interleukin 6 (IL-6) receptor in vivo: sensitization of human soluble IL-6 receptor transgenic mice towards IL-6 and prolongation of the plasma half-life of IL-6.

Interleukin 6 (IL-6) is considered an important mediator of acute inflammatory responses. Moreover, IL-6 functions as a differentiation and growth factor of hematopoietic precursor cells, B cells, T cells, keratinocytes, neuronal cells, osteoclasts, and endothelial cells. IL-6 exhibits its action via a receptor complex consisting of a specific IL-6 receptor (IL-6R) and a signal transducing subunit (gp130). Soluble forms of both receptor components are generated by shedding and are found in patients with various diseases such as acquired immune deficiency syndrome, rheumatoid arthritis, and others. The function of the soluble (s)IL-6R in vivo is unknown. Since human (h)IL-6 acts on human and…

A new hepatocyte stimulating factor: cardiotrophin-1 (CT-1)

Abstract Recently, a novel cytokine, cardiotrophin-1 (CT-1), was cloned and found to induce cardiac myocyte hypertrophy in vitro. Amino acid sequence similarity showed CT-1 to be a member of the IL-6/LIF/CNTF/OSM/IL-11 cytokine family. Since all known members of the IL-6 cytokine family induce an hepatic acute phase protein (APP) gene expression, we investigated the ability of CT-1 to induce a liver acute phase response. Upon stimulation of rat hepatoma cells, CT-1 and LIF induced the strongest rat fibrinogen mRNA expression, OSM and IL-6 induced a less pronounced response. When human hepatoma cells and primary rat hepatocytes were stimulated with CT-1, the expression of human haptoglobin a…

Mycophenolate mofetil for treatment of active inflammatory bowel disease. Clinical and immunological studies.

Hepatocellular Hyperplasia, Plasmacytoma Formation, and Extramedullary Hematopoiesis in Interleukin (IL)-6/Soluble IL-6 Receptor Double-Transgenic Mice

Cytokines interact not only with membrane anchored receptors, but also with specific soluble receptors which circulate in the bloodstream. In general, soluble cytokine receptors such as soluble tumor necrosis factor receptor, soluble interleukin 1 receptor, and soluble interleukin 4 receptor compete with their membrane-bound counterparts for the ligands and therefore act as antagonists. In contrast, soluble receptors for cytokines of the interleukin-6 (IL-6) family complex with their ligands act agonistically. Interestingly, the complex of IL-6 and the soluble interleukin 6 receptor (sIL-6R) activates target cells that do not express the membrane-bound IL-6R and therefore cannot respond to …

Mycophenolate mofetil versus azathioprine in patients with chronic active ulcerative colitis: a 12-month pilot study.

Ulcerative colitis (UC) is an inflammatory bowel disease (IBD) of unknown etiology frequently requiring long-term therapy for control of symptoms and prevention of relapse. Azathioprine (AZA) has been shown to be effective and safe in the treatment of chronic active UC. However, the alternatives to treatment with AZA are limited. Our aim was to compare the efficacy and safety of treatment with mycophenolate mofetil (MMF)/prednisolone versus standard immunosuppressive treatment with azathioprine (AZA)/prednisolone in patients with chronic active UC.The study was designed as an open comparison of MMF versus AZA. Twenty-four patients with active UC (Rachmilewitz scoreor =6 points) were randoml…

Combined interleukin 6 and soluble interleukin 6 receptor accelerates murine liver regeneration.

Abstract Background & Aims: Liver regeneration after loss of hepatic tissue leads to hepatocyte and nonparenchymal cell proliferation and rapid restoration of liver parenchyma. Interleukin (IL)-6 is a key inducer of transcription factors involved in liver regeneration. Whenever IL-6 activates target cells, it binds to a specific IL-6 receptor (IL-6R). The IL-6/IL-6R complex then associates with the signal transducer gp130, leading to activation of intracellular signaling. Methods: We have recently constructed the designer cytokine Hyper-IL-6 consisting of soluble IL-6R covalently linked to IL-6, which directly stimulates gp130 even in the absence of membrane-bound IL-6R. We compared the inf…

Coexpression of IL-6 and soluble IL-6R causes nodular regenerative hyperplasia and adenomas of the liver

Studies with tumor necrosis factor p55 receptor- and interleukin-6 (IL-6)-deficient mice have shown that IL-6 is required for hepatocyte proliferation and reconstitution of the liver mass after partial hepatectomy. The biological activities of IL-6 are potentiated when this cytokine binds soluble forms of its specific receptor subunit (sIL-6R) and the resulting complex interacts with the transmembrane signaling chain gp130. We show here that double transgenic mice expressing high levels of both human IL-6 and sIL-6R under the control of liver-specific promoters spontaneously develop nodules of hepatocellular hyperplasia around periportal spaces and present signs of sustained hepatocyte prol…

Interleukin-6 and the soluble interleukin-6 receptor induce stem cell factor and Flt-3L expression in vivo and in vitro.

Abstract Objective We recently established transgenic animals expressing either interleukin-6 (IL-6) or the soluble IL-6 receptor (sIL-6R) alone, or both components, IL-6 and the sIL-6R, in the liver. This animal model demonstrated that the expression of IL-6 in combination with its sIL-6R led to extramedullary expansion of hematopoietic progenitor cells in the spleen and liver. Materials and Methods We studied other relevant hematopoietic cytokines involved in the IL-6/sIL-6R–induced stimulation of hematopoiesis. Results Using immunohistochemistry, we showed that cell-associated stem cell factor (SCF) and Flt-3L expression were upregulated in liver and spleen only in double transgenic mice…

SHEDDING OF THE INTERLEUKIN-6 RECEPTOR: MECHANISMS AND PHYSIOLOGICAL CONSEQUENCES

Posttransfusional, LKM-1-autoantibody-positive hepatitis C virus infection, cryoglobulinemia, and aplastic anemia.

Aplastic anemia is occasionally caused by viral hepatitis, hepatitis C virus being the most important factor. Pathogenetically, decreased bone marrow function, abnormalities of the bone marrow microenvironment, and immune-mediated suppression of hematopoiesis are important. Hepatitis C virus infection is associated with a variety of extrahepatic manifestations including autoimmune features like cryoglobulinemia, Sjogren's syndrome, and autoimmune hepatitis. Here we report the case of a 42-year-old man with aplastic anemia due to posttransfusional hepatitis C virus infection associated with cryoglobulinemia and LKM-1 autoantibodies. Following a triple immunosuppressive therapy, there was a c…

Interleukin-6 and Soluble Interleukin-6 Receptor: Direct Stimulation of gp130 and Hematopoiesis

T HE INTERLEUKIN-6 (IL-6) family of cytokines acts via receptor complexes that contain at least one subunit of the signal transducing protein gp130.[1][1] The family comprises IL-6, IL-11, ciliary neurotrophic factor (CNTF), cardiotrophin-1 (CT-1), leukemia inhibitory factor (LIF), and oncostatin M