Oncostatin M: foe or friend?

Parkinson's Disease and MicroRNAs: A Duel Between Inhibition and Stimulation of Apoptosis in Neuronal Cells

Parkinson's disease (PD) is one of the most prevalent diseases of central nervous system that is caused by degeneration of the substantia nigra's dopamine-producing neurons through apoptosis. Apoptosis is regulated by initiators' and executioners' caspases both in intrinsic and extrinsic pathways, further resulting in neuronal damage. In that context, targeting apoptosis appears as a promising therapeutic approach for treating neurodegenerative diseases. Non-coding RNAs-more especially, microRNAs, or miRNAs-are a promising target for the therapy of neurodegenerative diseases because they are essential for a number of cellular processes, including signaling, apoptosis, cell proliferation, and gene regulation. It is estimated that a substantial portion of coding genes (more than 60%) are regulated by miRNAs. These small regulatory molecules can have wide-reaching consequences on cellular processes like apoptosis, both in terms of intrinsic and extrinsic pathways. Furthermore, it was recommended that a disruption in miRNA expression levels could also result in perturbation of typical apoptosis pathways, which may be a factor in certain diseases like PD. The latest research on miRNAs and their impact on neural cell injury in PD models by regulating the apoptosis pathway is summarized in this review article. Furthermore, the importance of lncRNA/circRNA-miRNA-mRNA network for regulating apoptosis pathways in PD models and treatment is explored. These results can be utilized for developing new strategies in PD treatment.

Insight into adipokines to optimize therapeutic effects of stem cell for tissue regeneration

Stem cell therapy is considered as a promising regenerative medicine for repairing and treating damaged tissues and/or preventing various diseases. But there are still some obstacles such as low cell migration, poor stem cell engraftment and decreased cell survival that need to be overcome before transplantation. Therefore, a large body of studies has focused on improving the efficiency of stem cell therapy. For instance, preconditioning of stem cells has emerged as an effective strategy to reinforce therapeutic efficacy. Adipokines are signaling molecules, secreted by adipose tissue, which regulate a variety of biological processes in adipose tissue and other organs including the brain, liver, and muscle. In this review article, we shed light on the biological effects of some adipokines including apelin, oncostatin M, omentin-1 and vaspin on stem cell therapy and the most recent preclinical advances in our understanding of how these functions ameliorate stem cell therapy outcome.

Prokaryotic soluble overexpression and purification of oncostatin M using a fusion approach and genetically engineered E. coli strains

Human Oncostatin M (OSM), initially discovered as a tumour inhibitory factor secreted from U-937 cells, is a gp130 (IL-6/LIF) cytokine family member that exhibits pleiotropic effects in inflammation, haematopoiesis, skeletal tissue alteration, liver regeneration, cardiovascular and metabolic diseases. Cytoplasmic expression of OSM in Escherichia coli results in inclusion bodies, and complex solubilisation, refolding and purification is required to prepare bioactive protein. Herein, eight N-terminal fusion variants of OSM with hexahistidine (His6) tag and seven solubility-enhancing tags, including thioredoxin (Trx), small ubiquitin-related modifier (Sumo), glutathione S-transferase (GST), maltose-binding protein (MBP), N-utilisation substance protein A (Nusa), human protein disulphide isomerase (PDI) and the b‘a’ domain of PDI (PDIb‘a’), were tested for soluble OSM expression in E. coli. The His6-OSM plasmid was also introduced into genetically engineered Origami 2 and SHuffle strains to test expression of the protein. At 18 °C, MBP-tagged OSM was highly expressed and solubility was dramatically enhanced. In addition, His6-OSM was more highly expressed and soluble in Origami 2 and SHuffle strains than in BL21(DE3). MBP-OSM and His6-OSM were purified more than 95% with yields of 11.02 mg and 3.27 mg from a 500 mL culture. Protein identity was confirmed by mass spectroscopy, and bioactivity was demonstrated by in vitro inhibition of Th17 cell differentiation.

Effect of Estriol, Chorionic Gonadotropin, and Oncostatin M on the Expression of Recombinase RAG-1 in Regulatory T Lymphocyte Subpopulations

We studied the effect of estriol, chorionic gonadotropin, oncostatin M, and hormone-cytokine combinations on the expression of recombinase RAG-1 in T-regulatory (Treg) and T helper 17 (Th17) lymphocytes. It was found that estriol in a concentration corresponding to the first trimester of pregnancy increased the level of Treg (CD4⁺FoxP3⁺) cells and suppressed the formation of Th17 (CD4⁺RORC⁺) lymphocytes. This effect was nor observed after individual administration of chorionic gonadotropin and oncostatin M, but some combinations of the studied hormones with oncostatin M increased the percentage of CD4⁺FOXP3⁺ cells. In the presence of oncostatin M, the studied hormones enhanced the expression of RAG-1 in CD4⁺FoxP3⁺ cells, but not in CD4⁺RORC⁺ cells, thereby initiating of Treg T-cell receptor (TCR) revision. The mechanisms of hormone cytokine control of induction of the immune tolerance during pregnancy are discussed.

Regulation of Recombinase Rag-1 Expression by Female Sex Steroids in Treg and Th17 Lymphocytes: Role of Oncostatin M

The effect of estradiol (E₂), progesterone (P₄), and oncostatin M (OSM) on the differentiation of CD4⁺ T cells to T regulatory (Treg) lymphocytes and T helpers 17 (Th17) was investigated. The possibility of revision of the T cell receptor in these subpopulations by evaluating the expression of RAG-1 recombinase was also studied. E₂ at concentrations characteristic of pregnancy trimester I, but no P₄ or OSM, increased the Treg level. Combination of sex steroids with OSM increased the percent of CD4⁺FOXP3⁺ cells and enhanced RAG-1 expression in these cells, thus promoting the development of immune tolerance during pregnancy. In the study of Th17, such effect of the hormones and OSM was not detected.

Inflammatory and anti-inflammatory markers in plasma: from late pregnancy to early postpartum

During pregnancy, the woman's body undergoes tremendous changes in immune system adaptation. The immunological shifts that occur in pregnancy can partially be explained by alterations in hormonal levels. Furthermore, during pregnancy, many autoimmune diseases go into remission, only to flare again in the early postpartum period. Given these important changes in the clinical course of a number of autoimmune disorders, surprisingly little has been done to investigate the inflammatory profile changes across pregnancy and the postpartum period. Thus, the aim of this study was to describe how inflammatory and anti-inflammatory markers change from late pregnancy to the early postpartum period, using a multiplexed assay consisting of both well-known as well as exploratory proteins. Two-hundred-and-ninety women were included in this study and donated a total of 312 blood samples; 198 in late pregnancy (~gw38) and 114 in the postpartum period (~w8). The plasma blood samples were analyzed for 92 immune system related protein markers using Proseek Multiplex Inflammation I panel, a high-sensitivity assay based on proximity extension assay technology. Fifty-six inflammatory and anti-inflammatory markers were significantly different between pregnancy and the postpartum, of which 50 survived corrections for multiple comparisons. Out of these 50 markers, 41 decreased from pregnancy to postpartum, while the remaining 9 increased in the postpartum period. The top five markers with the greatest decrease in the postpartum period were Leukemia inhibitory factor receptor (LIF-R), Latency-associated peptide Transforming growth factor beta-1 (LAP TGF-beta-1), C-C motif chemokine 28 (CCL28), Oncostatin M (OSM) and Fibroblast growth factor 21 (FGF21). Top three markers that increased in the postpartum period were Tumor necrosis factor ligand superfamily member 11 (TRANCE), Tumor necrosis factor ligand superfamily member 12 (TWEAK), and C-C motif chemokine/Eotaxin (CCL11). This study revealed that the majority of the markers decreased from pregnancy to postpartum, and only a few increased. Several of the top proteins that were higher in pregnancy than postpartum have anti-inflammatory and immune modulatory properties promoting pregnancy progress. These results clearly reflect the tremendous change in the immune system in the pregnancy to postpartum transition.

Overexpression of microRNA-183 promotes apoptosis of substantia nigra neurons via the inhibition of OSMR in a mouse model of Parkinson's disease

The present study aimed to investigate the effect of microRNA-183 (miR-183) on substantia nigra neurons by targeting oncostatin M receptor (OSMR) in a mouse model of Parkinson’s disease (PD). The positive expression rates of OSMR and the apoptosis of substantia nigra neurons were detected by immunohistochemistry and terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end-labeling, respectively. Substantia nigra neurons in normal and PD mice were cultured in vitro. The association between miR-183 and OSMR was verified using a dual luciferase reporter gene assay. The expression of miR-183 and the phosphoinositide 3-kinase-Akt signaling pathway-associated genes were detected by reverse transcription-quantitative polymerase chain reaction and western blot analysis, respectively. Cell apoptosis was detected by flow cytometry. OSMR is the target gene of miR-183. The number of OSMR-positive cells and the apoptotic rate of substantia nigra neurons were increased in the PD group. Neurons transfected with miR-183 mimic exhibited elevated expression levels of miR-183, B-cell lymphoma 2 (Bcl-2)-associated X protein (Bax) and caspase-9 and increased apoptotic rate, and reduced expression levels of OSMR, Akt, phosphorylated (p-)Akt, glycogen synthase kinase-3 (GSK-3β), p-GSK-3β, Bcl-2, insulin-like growth factor 1 (IGF-1), mammalian target of rapamycin (mTOR) and p-mTOR. The miR-183 inhibitor decreased the expression levels of miR-183, Bax and caspase-9 and the apoptotic rate; however, increased the expression of OSMR, Akt, p-Akt, GSK-3β, p-GSK-3β, Bcl-2, IGF-1, mTOR and p-mTOR. The results of the present study provide evidence that the overexpression of miR-183 promotes the apoptosis of substantia nigra neurons by inhibiting the expression of OSMR.

The role of oncostatin M regulates osteoblastic differentiation of dental pulp stem cells through STAT3 pathway

Dental pulp stem cells (DPSCs) are a type of mesenchymal stem cells, which have the self-renewal and multi-lineage differentiation potential, including chondrocytes, adipocytes, neural cells and osteoblasts. So they play a significant role in pulp repair and bone regeneration. Oncostatin M (OSM), one of the IL-6 family cytokines, inhibits adipogenic differentiation and stimulates osteogenic differentiation of human bone marrow mesenchymal stem cells. However, the effect of OSM on DPSCs is unclear. We found that OSM induced osteogenic differentiation of DPSCs, promoting matrix mineralization as measured by Alizarin Red S staining. OSM also increased expression of osteogenesis-associated gene products Alkaline phosphatase, Bone morphogenetic protein 2 (BMP2), Runt-related transcription factor 2 and Osteocalcin (OCN) as assessed by immunoblotting. We also found that OSM activated the Signal Transducer And Activator Of Transcription 3 (STAT3) pathway during the osteogenic differentiation of DPSCs. Blocking the osteogenic differentiation by silencing of STAT3 can significantly inhibit OSM-induced osteogenic differentiation of DPSCs and the expression of related genes, furthermore matrix mineralization was also suppressed. In summary, OSM promotes osteoblastic differentiation of DPSCs and osteogenesis-related genes expression through the JAK3/STAT3 signaling pathway which may be useful for the autologous transplantation of DPSCs.

Induction of STAT3-Dependent CXCL5 Expression and Neutrophil Recruitment by Oncostatin-M during Pneumonia

Acute bacterial pneumonia is a significant public health concern worldwide. Understanding the signals coordinating lung innate immunity may foster the development of therapeutics that limit tissue damage and promote host defense. We have previously shown that lung messenger RNA expression of the IL-6 family cytokine oncostatin-M (OSM) is significantly elevated in response to bacterial stimuli. However, its physiological significance during pneumonia is unknown. Here we demonstrate that OSM is rapidly increased in the airspaces of mice after pulmonary infection with Escherichia coli. Neutralization of OSM caused a substantial decrease in airspace neutrophils and macrophages. OSM blockade also caused a marked reduction in lung chemokine (C-X-C motif) ligand (CXCL) 5 expression, whereas other closely related neutrophil chemokines, CXCL1 and CXCL2, were unaffected. Intratracheal administration of recombinant OSM was sufficient to recapitulate the effect on CXCL5 induction, associated with robust activation of the signal transducer and activator of transcription 3 (STAT3) transcription factor. Cell sorting revealed that OSM effects were specific to lung epithelial cells, including a positive feedback loop in which OSM may facilitate expression of its own receptor. Finally, in vitro studies demonstrated that STAT3 was required for maximal OSM-induced CXCL5 expression. These studies demonstrate a novel role for OSM during pneumonia as an important signal to epithelial cells for chemokine induction mediating neutrophil recruitment.

Advances in understanding the relationship between oncostatin M and liver regeneration and liver diseases

Oncostatin M (OSM) is a pleiotropic cytokine belonging to the interleukin (IL)-6 family of cytokines. It is closely related structurally and functionally to leukemia inhibitory factor (LIF). There are two types of functional OSM receptors (OSMR): I and II. The binding of OSM to its receptors activates the JAK-STAT and MAPK signal pathways. OSM not only inhibits the proliferation of tumor cells but also participates in several physiological and pathological processes in a variety of cell types and plays key roles in the pathogenesis of multiple diseases, including regulation of inflammatory responses, stimulation of hematopoiesis, regulation of cholesterol metabolism, and induction of neurotrophic peptides. Recent studies suggest that OSM participates in liver regeneration and is closely related to the occurrence and progression of viral hepatitis, non-alcoholic fatty liver disease, liver fibrosis, and liver cancer. This article reviews recent advances in understanding the relationship between OSM and liver generation and liver diseases.

Blocking MAPK signaling downregulates CCL21 in lymphatic endothelial cells and impairs contact hypersensitivity responses

CCL21 expression by lymphatic endothelial cells (LECs) is essential for migration of CCR7+ immune cells from skin to regional lymph nodes (LNs). We investigated the importance of mitogen-activated protein kinase (MAPK) signaling in CCL21 expression by ECs in vitro and in vivo. Normal human dermal lymphatic microvascular ECs (HMVEC-dLy) stimulated in vitro with oncostatin M (OSM) expressed high amounts of CCL21 mRNA. CCL21 protein expression by HMVEC-dLy was also markedly increased by OSM compared with unstimulated cultures. Marked phosphorylation of MAPK 44/42 was detected in HMVEC-dLy stimulated by OSM. CCL21 expression by HMVEC-dLy was blocked by a JAK inhibitor 1, JAK3 inhibitor, and U0126 (a MAPK kinase inhibitor) in vitro, all of which blocked phosphorylation of MAPK 44/42. In addition, injection of U0126 into murine skin significantly decreased CCL21 mRNA and protein expression. Moreover, injection of U0126 before sensitization decreased migration of dendritic cells to draining LNs and decreased contact hypersensitivity responses. In summary, these results suggest that the MAPK pathway is important for CCL21 expression by LECs in vitro and in vivo. Blocking MAPK signaling within skin may offer a novel approach to treatment of inflammatory skin diseases.

A receptor fusion protein for the inhibition of murine oncostatin M

Background

Most cytokines signal through heteromeric receptor complexes consisting of two or more different receptor subunits. Fusion proteins of the extracellular parts of receptor subunits turned out to be promising cytokine inhibitors useful in anti-cytokine therapy and cytokine research.

Results

We constructed receptor fusion proteins (RFP) consisting of the ligand binding domains of the murine oncostatin M (mOSM) receptor subunits mOSMR and mgp130 connected by a flexible linker as potential mOSM inhibitors. mgp130 is a shared cytokine receptor that is also used by other cytokines such as IL-6 and leukemia inhibitory factor (LIF). In this study we compare four types of mOSM-RFPs that contain either domains D1-D3 or domains D2-D3 of mgp130 and are arranged in two ways. Domain D1 of mgp130 turned out to be dispensable for mOSM-binding. However, the arrangement of the two receptor subunits is essential for the inhibitory activity. We found mOSM induced STAT3 phosphorylation to be suppressed only when the mOSMR fragment was fused in front of the mgp130 fragment.

Conclusions

mOSM-RFP consisting of D1-D4 of mOSMR and D2-D3 of mgp130 is a highly potent and specific inhibitor of mOSM. Since mOSM-RFP is encoded by a single gene it offers numerous possibilities for specific cytokine inhibition in gene delivery approaches based on viral vectors, transgenic animals and finally gene therapy.

Thrombin induces the expression of oncostatin M via AP-1 activation in human macrophages: a link between coagulation and inflammation

Macrophages as inflammatory cells are involved in the pathogenesis of atherosclerosis that today is recognized as an inflammatory disease. Activation of coagulation leads to the late complication of atherosclerosis, namely atherothrombosis with its clinical manifestations stroke, unstable angina, myocardial infarction, and sudden cardiac death. Thus inflammation and coagulation play fundamental roles in the pathogenesis of atherosclerosis. We show that the coagulation enzyme thrombin up-regulates oncostatin M (OSM), a pleiotropic cytokine implicated in the pathophysiology of vascular disease, in human monocyte-derived macrophages (MDMs) up to 16.8-fold. A similar effect was seen in human peripheral blood monocytes and human plaque macrophages. In MDMs, the effect of thrombin on OSM was abolished by PPACK and mimicked by a PAR-1-specific peptide. Thrombin induced phosphorylation of ERK1/2 and p38 in MDMs. The ERK1/2 inhibitor PD98059 blocked the effect of thrombin on OSM production in MDMs, whereas the p38 inhibitor SB202190 had no effect. Thrombin induced translocation of c-fos and c-jun to the nucleus of MDMs. Using OSM promoter-luciferase reporter constructs transfected into MDMs, we show that a functional AP-1 site is required for promoter activation by thrombin. We present another link between coagulation and inflammation, which could impact on the pathogenesis of atherosclerosis.

Mice overexpressing murine oncostatin M (OSM) exhibit changes in hematopoietic and other organs that are distinct from those of mice overexpressing human OSM or bovine OSM

Oncostatin M (OSM) and leukemia inhibitory factor (LIF) belong to the interleukin-6 family of cytokines. The authors' previous in vitro work demonstrated that in mouse cells mouse OSM (mOSM) signals through a heterodimeric receptor complex incorporating the mOSM-specific receptor mOSMRbeta while human OSM (hOSM) and bovine OSM (bOSM) use the mouse LIF receptor mLIFRbeta rather than mOSMRbeta. These in vitro data suggest that prior studies in mouse systems with hOSM or bOSM (the usual molecules used in early studies) reflect LIF rather than OSM biology. The current work assessed whether or not this divergence in actions among these three OSMs also occurs in vivo in mouse models. Adult female (C57BL/6J x DBA/2J) F(1) mice were engineered to stably overexpress mOSM, hOSM, or bOSM by retrovirus-mediated gene transfer (n = 10 or more per group). After 4 weeks, molecular and hematologic profiles and anatomic phenotypes in multiple organs were assessed by standard techniques. Animals overexpressing either hOSM or bOSM had an identical phenotype resembling that associated with LIF activation, including significant hematologic abnormalities (anemia, neutrophilia, lymphopenia, eosinopenia, and thrombocytosis); weight loss; profound enlargement (lymph node, spleen) and/or structural reorganization (lymph node, spleen, thymus) of lymphoid organs; and severe osteosclerosis. In contrast, mice overexpressing mOSM did not develop hematologic changes, weight loss, or osteosclerosis and exhibited more modest and anatomically distinct restructuring of lymphoid organs. These data indicate that activities imputed to OSM and the mOSMRbeta signaling pathway using in vitro and in vivo mouse experimental systems are unique to mOSM.

Signal transduction and cell-type specific regulation of matrix metalloproteinase gene expression: can MMPs be good for you?

An abundance of literature over the past several years indicates a growing interest in the role of matrix metalloproteinases (MMPs) in normal physiology and in disease pathology. MMPs were originally defined by their ability to degrade the extracellular matrix, but it is now well documented that their substrates extend far beyond matrix components. Recent reviews discuss the structure and function of the MMP family members, as well as the promoter sequences that control gene expression. Thus, we focus on the signal transduction pathways that confer differential cell-type expression of MMPs, as well as on some novel non-matrix degrading functions of MMPs, particularly their intracellular location where they may contribute to apoptosis. In addition, increasing data implicate MMPs as "good guys", protective agents in some cancers and in helping to resolve acute pathologic conditions. Despite the intricate and complicated roles of MMPs in physiology and pathology, the goal of designing therapeutics that can selectively target MMPs remains a major focus. Developing MMP inhibitors with targeted specificity will be difficult; success will depend on understanding the role of these enzymes in homeostasis and on the careful delineation of mechanisms by which this family of enzymes mediates disease pathology.

Mechanism of proteoglycan aggregate degradation in cartilage stimulated with oncostatin M

OBJECTIVE

To investigate the potential synergistic and differential effects of cytokine combinations on proteoglycan aggregate catabolism in cartilage.

METHODS

Bovine articular cartilage explants were maintained in organ culture and subjected to stimulation with cytokine combinations including interleukin-1alpha (IL-1alpha), IL-1beta, IL-6, IL-17, tumor necrosis factor-alpha (TNFalpha) and oncostatin M (OSM). Aggrecan, link protein and hyaluronan (HA) release and degradation were analyzed, and the effect of the hyaluronidase inhibitor apigenin was investigated.

RESULTS

For all cytokine mixtures studied cleavage of aggrecan only by aggrecanase action was apparent. However, OSM acting synergistically with IL-1 or TNFalpha produced a rapid release of all proteoglycan aggregate components due to both aggrecan and HA degradation. This was abolished by the hyaluronidase inhibitor, apigenin. In addition, in the presence of OSM a low molecular weight aggrecan G3 product was observed, suggesting altered aggrecanase cleavage activity is induced by this cytokine.

CONCLUSIONS

Under cytokine stimulation, aggrecan release from cartilage may take place via proteolysis of the aggrecan core protein or via depolymerization of HA, with the latter mechanism being induced by OSM. OSM is associated with joint inflammation and its participation may account for the more rapid loss of aggrecan from articular cartilage in the inflammatory arthritides, compared to osteoarthritis.

Oncostatin M Enhances CCL21 Expression by Microvascular Endothelial Cells and Increases the Efficiency of Dendritic Cell Trafficking to Lymph Nodes

CCL21, a lymphatic endothelial cell (LEC)-derived chemokine, and its receptor CCR7 regulate dendritic cell (DC) trafficking to lymph nodes (LN), but it is unclear how CCL21 expression is regulated. Oncostatin M (OSM) is an IL-6-like cytokine synthesized by activated DC and other leukocytes. In vitro, OSM (but not TNF-alpha) stimulated CCL21 mRNA and protein expression by human dermal microvascular EC (DMEC) in an ERK1/2-dependent fashion. Conditioned medium from OSM-treated DMEC stimulated CCL21-dependent chemotaxis of mouse bone marrow-derived DC (BMDC). Cultured BMDC expressed OSM, which was increased with the addition of LPS. Topical application of the contact-sensitizing hapten, trinitrochlorobenzene, resulted in enhanced OSM expression in the skin, whereas cutaneous injection of TNF-alpha did not. Injection of OSM into the footpad increased CCL21 mRNA expression in the draining LN by approximately 10-fold and in mouse skin by approximately 4-fold without increasing CCR7 mRNA. In vitro, OSM increased the permeability of DMEC and lung microvascular EC monolayers to FITC-dextran beads, and, in vivo, it enhanced accumulation of Evans blue dye in draining LN by approximately 3-fold (p = 0.0291). Of note, OSM increased trafficking of BMDC injected in footpads to draining LN by 2-fold (p = 0.016). In summary, OSM up-regulates CCL21 expression in skin and draining regional LN. We propose that OSM is a regulator of CCL21 expression and endothelial permeability in skin, contributing to efficient migration of DC to regional LN.

Oncostatin M induces angiogenesis and cartilage degradation in rheumatoid arthritis synovial tissue and human cartilage cocultures

OBJECTIVE

To investigate the role of oncostatin M (OSM) in cell adhesion, angiogenesis, and matrix degradation in rheumatoid arthritis (RA) synovial tissue and normal human cartilage.

METHODS

Human dermal microvascular endothelial cell (HDMEC) and RA synovial fibroblast (RASF) proliferation and intercellular adhesion molecule 1 (ICAM-1) and vascular cell adhesion molecule 1 (VCAM-1) expression were assessed by a bromodeoxyuridine proliferation assay and flow cytometry. HDMEC tubule formation and migration were assessed by Matrigel culture and migration assay. Production of matrix metalloproteinase (MMP) and tissue inhibitor of metalloproteinases 1 (TIMP-1) in RA synovial explants, and proteoglycan/glycosaminoglycan (GAG) release, vascular endothelial growth factor (VEGF), and angiopoietin 2 production from RASF/normal cartilage cocultures were assessed by enzyme-linked immunosorbent assay and immunohistology.

RESULTS

HDMEC/RASF proliferation was induced by OSM and interleukin-1beta (IL-1beta), alone and in combination. OSM enhanced cell surface expression of ICAM-1, but not VCAM-1, on endothelial cells and RASFs. OSM increased endothelial cell tubule formation and migration. In RA synovial explants, OSM induced production of MMP-1 and TIMP-1. When OSM was combined with IL-1beta, however, the MMP-1:TIMP-1 ratio was significantly increased. OSM potentiated IL-1beta-induced MMP-1 and MMP-13 expression in normal human cartilage/RASF cocultures, resulting in a significant increase in the MMP:TIMP ratio. In OSM/IL-1beta- stimulated cocultures, cartilage sections demonstrated significant proteoglycan depletion that was paralleled by a significant increase in GAG release in supernatants. Finally, compared with either cytokine alone, the combination of OSM and IL-1beta significantly induced VEGF production in RASF/cartilage cocultures.

CONCLUSION

These data suggest that OSM promotes angiogenesis and endothelial cell migration and potentiates the effects of IL-1beta in promoting extracellular matrix turnover and human cartilage degradation. Furthermore, the induction of VEGF in cocultures supports the hypothesis of a link between angiogenesis and cartilage degradation.

Pharmacological regulation of low density lipoprotein receptor expression: Current status and future developments

Plasma levels of low-density lipoprotein (LDL) cholesterol are considered to be a major risk factor for the development of cardiovascular diseases. The LDL receptor is the key component in the maintenance of cholesterol homeostasis in the body, playing a pivotal role by regulating the hepatic catabolism of LDL cholesterol. Many clinical studies using statins, which up-regulate the LDL receptor expression via a feedback mechanism, have demonstrated that the reduction of LDL cholesterol levels lowers the incidence of cardiovascular events in both primary and secondary prevention. In this context, new strategies designed to increase hepatic LDL receptor activity can be considered as attractive opportunities for future therapy. Several potential new drugs have been described in the last decade to up-regulate LDL receptor expression in vitro and in vivo, thus allowing the identification of new transcriptional and post-transcriptional mechanisms.

Oncostatin M induces proliferation of human adipose tissue-derived mesenchymal stem cells

Interleukin-6 (IL-6) subfamily of cytokines, including oncostatin M (OSM), leukemia inhibitory factor (LIF), and IL-6, has been implicated in a variety of physiological responses, such as cell growth, differentiation, and inflammation. In the present study, we demonstrated that both OSM and LIF stimulated the proliferation of human adipose tissue-derived mesenchymal stem cells (hATSCs), however, IL-6 had no effect on cell proliferation. OSM treatment induced phosphorylation of ERK, and pretreatment with U0126, a MEK inhibitor, prevented the OSM-stimulated proliferation of hATSCs, suggesting that the MEK/ERK pathway is involved in the OSM-induced proliferation. Treatment with OSM also induced phosphorylation of JAK2 and JAK3, and pretreatment of the cells with WHI-P131, a JAK3 inhibitor, but not with AG490, a JAK2 inhibitor, attenuated the OSM-induced proliferation of hATSCs. Furthermore, OSM treatment elicited phosphorylation of STAT1 and STAT3, and pretreatment with WHI-P131 specifically prevented the OSM-induced phosphorylation of STAT1, without affecting the OSM-induced phosphorylation of ERK and STAT3. These results suggest that two separate signaling pathways, such as MEK/ERK and JAK3/STAT1, are independently involved in the OSM-stimulated proliferation of hATSCs.

Cytokine networks—towards new therapies for rheumatoid arthritis

Success achieved so far in the blockade of tumor necrosis factor and interleukin (IL)-1 in rheumatoid arthritis exemplifies the feasibility and potential therapeutic application of antagonizing cytokine signaling. Despite these advances, there remains a considerable unmet clinical need in this field. A number of preclinical development programs are ongoing to target a variety of cytokines that are central to immune regulation and tissue-matrix destruction in rheumatoid arthritis. Evidence indicates that IL-6 antagonists might represents a useful approach and preliminary data similarly identify IL-15 as an intriguing target. Numerous additional cytokines are under investigation at the preclinical stage, including IL-12-IL-23, IL-17 and IL-18. As therapeutic goals move from disease control towards remission induction, development of the capacity for cytokine targeting to modify the underlying immune dysregulation remains a major priority.

Raf and VEGF: emerging therapeutic targets in Kaposi's sarcoma-associated herpesvirus infection and angiogenesis in hematopoietic and nonhematopoietic tumors

Kaposi's sarcoma-associated herpesvirus (KSHV) is etiologically associated with several cancers including Kaposi's sarcoma (KS), primary effusion lymphoma, and multicentric Castleman's disease. KSHV-mediated pathogenesis is dependent mainly on KSHV infection as well as on the microenvironment provided by the growth factors (GFs)/inflammatory cytokines (ICs). Recently, we determined that oncoprotein Raf enhances KSHV infection of target cells. Interestingly, Raf regulates the expression of a variety of GFs/ICs including those involved in angiogenesis such as vascular endothelial growth factor (VEGF). In this review, we discuss the effect of the Raf-GF/IC autocrine/paracrine loop on KSHV infection of both hematopoietic and nonhematopietic cells, and associated disease conditions.