Gp130 Cytokine Research Articles

Oncostatin M Confers Neuroprotection against Ischemic Stroke.

OSM, a member of the gp130 cytokine family, regulates neuronal function and survival. OSM engages a second receptor, either LIFRα or OSMRβ, before recruiting gp130. However, it is not clear whether OSM/OSMRβ signaling is involved in neuroprotection in the setting of ischemic stroke. Recent studies show that, compared with mouse disease models, the OSM receptor system in rats more closely resembles that in humans. In the present study, we use genetic manipulations of OSMRβ in both mouse and rat stroke models to demonstrate that OSMRβ in neurons is critical for neuronal survival during cerebral ischemic/reperfusion. Interestingly, administration of human OSM also leads to improved stroke outcomes. Therefore, OSM may represent a promising drug candidate for stroke treatment.

Abstract 4183: Differential expression of VEGF in breast cancer cells induced by gp130 cytokines

Abstract Glycoprotein 130 (gp130) is a glycosylated type 1 membrane protein and functions as a cytokine receptor modulating activity of the interleukin-6 (IL-6) family cytokines, which include IL-6, IL-11, IL-27, oncostatin M (OSM), leukemia inhibitory factor (LIF), ciliary neurotrophic factor (CNTF), cardiotrophin 1 (CT-1), cardiotrophin-like cytokine (CLC), and neuropoietin (NP). This study was designed to determine differential expression of VEGF in breast cancer cells by IL-6 family cytokines, and to elucidate the molecular mechanisms and signaling pathways involved in cytokine-mediated VEGF induction. Triple negative breast cancer (TNBC) MDA-MB-231 and estrogen receptor positive/progesterone receptor positive/Her2 negative (ER+/PR+/Her2-) T47D cells were treated with three cytokines (25 ng/mL), OSM, IL-6, and LIF, and analyzed. Our results showed that all three cytokines increased levels of HIF1α by Western blot analysis. OSM lead to a greater production of VEGF compared to IL-6 and LIF, as measured by enzyme-linked immunosorbent assay (ELISA) and as seen by luciferase reporter assay. Of the three cytokines, OSM alone induced VEGF in TNBC MDA-MB-231 cells, and this effect was mediated by signal transducer activator of transcription 3 (STAT3) signaling. However, both OSM and IL-6 increased VEGF secretion levels in ER+/PR+/Her2- T47D breast cancer cells, and this signaling was mediated by both HIF1α and pSTAT3, utilizing ELISA and Western blot analysis. These results implicate OSM as the key gp130 cytokine inducing VEGF secretion, and also suggest that this induction is not always HIF1α dependent and is cell-line specific. Citation Format: Danielle S. Hedeen, Ken Tawara, Madhuri Nandakumar, Ryan Fox, David Chang, Alex Ide, Andrew Oler, Dollie LaJoie, Cheryl L. Jorcyk. Differential expression of VEGF in breast cancer cells induced by gp130 cytokines. [abstract]. In: Proceedings of the 106th Annual Meeting of the American Association for Cancer Research; 2015 Apr 18-22; Philadelphia, PA. Philadelphia (PA): AACR; Cancer Res 2015;75(15 Suppl):Abstract nr 4183. doi:10.1158/1538-7445.AM2015-4183

Distinctive pro-inflammatory gene signatures induced in articular chondrocytes by oncostatin M and IL-6 are regulated by Suppressor of Cytokine Signaling-3

To describe gene expression in murine chondrocytes stimulated with IL-6 family cytokines and the impact of deleting Suppressor of Cytokine Signaling-3 (SOCS-3) in this cell type. Primary chondrocytes were isolated from wild type and SOCS-3-deficient (Socs3(Δ/Δcol2)) mice and stimulated with oncostatin M (OSM), IL-6 plus the soluble IL-6 receptor (IL-6/sIL-6R), IL-11 or leukemia inhibitory factor (LIF) for 4h. Total RNA was extracted and gene expression was evaluated by microarray analysis. Validation of the microarray results was performed using Taqman probes on RNA derived from chondrocytes stimulated for 1, 2, 4 or 8h. Gene ontology was characterized using DAVID (database for annotation, visualization and integrated discovery). Multiple genes, including Bcl3, Junb, Tgm1, Angptl4 and Lrg1, were upregulated in chondrocytes stimulated with each gp130 cytokine. The gene transcription profile in response to OSM stimulation was pro-inflammatory and was highly correlated to IL-6/sIL-6R, rather than IL-11 or LIF. In the absence of SOCS-3, OSM and IL-6/sIL-6R stimulation induced an interferon (IFN)-like gene signature, including expression of IL-31ra and S100a9. While each gp130 cytokine induced a transcriptional response in chondrocytes, OSM- and IL-6/sIL-6R were the most potent members of this cytokine family. SOCS-3 plays an important regulatory role in this cell type, as it does in hematopoietic cells. Our results provide new insights into a hierarchy of gp130-induced transcriptional responses in chondrocytes that is normally restrained by SOCS-3 and suggest therapeutic inhibition of OSM may have benefit over and above antagonism of IL-6 during inflammatory arthritis.

Differential Expression of IL-6/gp130 Cytokines, Jak-STAT Signaling and Neuroprotection After Müller Cell Ablation in a Transgenic Mouse Model.

It is anticipated that the interleukin-6/glycoprotein 130 (IL-6/gp130) family of cytokines and Jak-STAT signaling may be amenable to therapeutic manipulation for retinal diseases. Müller cells, which exhibit morphologic and functional changes in prevalent retinal diseases, are implicated in their induction and action. We characterized expression of endogenous IL-6/gp130 cytokines and Jak-STAT signaling after inducible Müller cell ablation in the neural retinas of adult mice. This resulted in photoreceptor apoptosis and reactive activation of surviving Müller cells. Analysis was performed by using a combination of quantitative real-time polymerase chain reaction, Western blot, and immunohistochemistry. Recombinant leukemia inhibitory factor (rLIF) was intravitreally injected in an attempt to inhibit photoreceptor degeneration following selective Müller cell ablation. Significant differential expression (both increases and decreases) of multiple IL-6/gp130 cytokines, such as LIF, oncostatin-M, and ciliary neurotrophic factor, occurred after Müller cell ablation, with concomitant increase in signal transducers and activators of transcription and extracellular kinases 1 and 2, particularly in surviving, activated Müller cells. Basic fibroblast growth factor was robustly increased in photoreceptors after selective Müller cell ablation. Multiple injections of rLIF failed to prevent photoreceptor degeneration. These results further characterize expression of IL-6/gp130 cytokines and Jak-STAT signaling in outer retinal disease, suggesting Müller cells are critical for their induction and action. Lack of rLIF-mediated neuroprotection contrasts with other retinal degenerations where Müller cell integrity remains intact or photoreceptor apoptosis occurs in a more rapid, synchronous manner. The presence of Müller cells may be critical for the functional benefits of rLIF and potentially other IL-6/gp130 cytokines.

Human amniotic epithelial cells: Proliferation and apoptosis during their hepatic differentiation

Human amniotic epithelial cells: Proliferation and apoptosis during their hepatic differentiation

Activation of the GP130-STAT3 axis and its potential implications in nonalcoholic fatty liver disease.

The status of the GP130-STAT3 signaling pathway in humans with nonalcoholic fatty liver disease (NAFLD) and its relevance to disease pathogenesis are unknown. The expression of the gp130-STAT3 axis and gp130 cytokine receptors were studied in subjects with varying phenotypes of NAFLD including nonalcoholic steatohepatitis (NASH) and compared with lean and weight-matched controls without NAFLD. Gp130 and its downstream signaling element (Tyk2 and STAT3) expression were inhibited in obese controls whereas they were increased in NAFLD. IL-6 levels were increased in NASH and correlated with gp130 expression (P < 0.01). Palmitate inhibited gp130-STAT3 expression and signaling. IL-6 and palmitate inhibited hepatic insulin signaling via STAT3-dependent and independent mechanisms, respectively. STAT3 overexpression reversed palmitate-induced lipotoxicity by increasing autophagy (ATG7) and decreasing endoplasmic reticulum stress. These data demonstrate that the STAT3 pathway is activated in NAFLD and can worsen insulin resistance while protecting against other lipotoxic mechanisms of disease pathogenesis.

Oncostatin m modulation of lipid storage.

Oncostatin M (OSM) is a cytokine belonging to the gp130 family, whose members serve pleiotropic functions. However, several actions of OSM are unique from those of other gp130 cytokines, and these actions may have critical roles in inflammatory mechanisms influencing several metabolic and biological functions of insulin-sensitive tissues. In this review, the actions of OSM in adipose tissue and liver are discussed, with an emphasis on lipid metabolism.

Cardiotrophin-1 (CT-1) improves high fat diet-induced cognitive deficits in mice.

Previous studies demonstrated that a high fat diet (HFD) results in a loss of working memory in mice correlated with neuroinflammatory changes as well as synaptodendritic abnormalities and brain insulin resistance. Cardiotrophin-1 (CT-1), a member of the gp130 cytokine family, has been shown to potentially play a critical role in obesity and the metabolic syndrome. Our recent studies have demonstrated that CT-1 attenuates cognitive impairment and glucose-uptake defects induced by amyloid-β in mouse brain through inhibiting GSK-3β activity. In this study, we evaluated the effect of CT-1 on cognitive impairment induced by brain insulin resistance in mice fed a HFD, and explored its potential mechanism. CT-1 (1 μg/day, intracerebroventricular injection) was given for 14 days to mice that were fed with either a HFD or normal diet for 18 weeks. After 20 weeks of treatment, our results showed that in the HFD group, CT-1 significantly improved learning and memory deficits and alleviated neuroinflammation demonstrated by decreasing brain levels of proinflammatory cytokine tumour necrosis factor-α and interleukin-1β, and increasing brain levels of anti-inflammatory cytokine IL-10. CT-1 significantly reduced body weight gain, restored normal levels of blood glucose, fatty acids and cholesterol. Furthermore, CT-1 significantly enhanced insulin/IGF signaling pathway as indicated by increasing the expression levels of insulin receptor substrate 1 (IRS-1) and the phosphorylation of Akt/GSK-3β, and reducing the phosphorylation of IRS-1 in the hippocampus compared to control. Moreover, CT-1 increased the level of the post-synaptic protein, PSD95, and drebrin, a dendritic spine-specific protein in the hippocampus. These results indicate a previously unrecognized potential of CT-1 in alleviating high-fat diet induced cognitive impairment.

Regulation of IL-17A responses in human airway smooth muscle cells by Oncostatin M.

BackgroundRegulation of human airway smooth muscle cells (HASMC) by cytokines contributes to chemotactic factor levels and thus to inflammatory cell accumulation in lung diseases. Cytokines such as the gp130 family member Oncostatin M (OSM) can act synergistically with Th2 cytokines (IL-4 and IL-13) to modulate lung cells, however whether IL-17A responses by HASMC can be altered is not known.ObjectiveTo determine the effects of recombinant OSM, or other gp130 cytokines (LIF, IL-31, and IL-6) in regulating HASMC responses to IL-17A, assessing MCP-1/CCL2 and IL-6 expression and cell signaling pathways.MethodsCell responses of primary HASMC cultures were measured by the assessment of protein levels in supernatants (ELISA) and mRNA levels (qRT-PCR) in cell extracts. Activation of STAT, MAPK (p38) and Akt pathways were measured by immunoblot. Pharmacological agents were used to assess the effects of inhibition of these pathways.ResultsOSM but not LIF, IL-31 or IL-6 could induce detectable responses in HASMC, elevating MCP-1/CCL2, IL-6 levels and activation of STAT-1, 3, 5, p38 and Akt cell signaling pathways. OSM induced synergistic action with IL-17A enhancing MCP-1/CCL-2 and IL-6 mRNA and protein expression, but not eotaxin-1 expression, while OSM in combination with IL-4 or IL-13 synergistically induced eotaxin-1 and MCP-1/CCL2. OSM elevated steady state mRNA levels of IL-4Rα, OSMRβ and gp130, but not IL-17RA or IL-17RC. Pharmacologic inhibition of STAT3 activation using Stattic down-regulated OSM, OSM/IL-4 or OSM/IL-13, and OSM/IL-17A synergistic responses of MCP-1/CCL-2 induction, whereas, inhibitors of Akt and p38 MAPK resulted in less reduction in MCP-1/CCL2 levels. IL-6 expression was more sensitive to inhibition of p38 (using SB203580) and was affected by Stattic in response to IL-17A/OSM stimulation.ConclusionsOncostatin M can regulate HASMC responses alone or in synergy with IL-17A. OSM/IL-17A combinations enhance MCP-1/CCL2 and IL-6 but not eotaxin-1. Thus, OSM through STAT3 activation of HASMC may participate in inflammatory cell recruitment in inflammatory airway disease.Electronic supplementary materialThe online version of this article (doi:10.1186/s12931-014-0164-4) contains supplementary material, which is available to authorized users.

Oncostatin M regulates osteogenic differentiation of murine adipose-derived mesenchymal progenitor cells through a PKCdelta-dependent mechanism.

Oncostatin M (OSM) is an IL-6/LIF family cytokine that influences mesenchymal progenitor differentiation; however, the mechanisms of this activity have not been fully elucidated. Using uncommitted murine adipose tissue-derived mesenchymal progenitors, we have examined mechanisms of OSM-induced osteogenesis. Murine OSM (mOSM) induced osteogenic differentiation to a greater degree than interleukin (IL)-6 and other members of the gp130 cytokine family, promoting extracellular matrix mineralization as indicated by Alizarin Red S staining. mOSM also increased expression of osteogenesis-associated gene products BMP4, BMP7, Runx-2, and osteocalcin as assessed by immunoblotting and real-time quantitative PCR. Additionally, protein kinase C (PKC) delta activity was upregulated in response to OSM stimulation, and to a greater degree than IL-6. Knockdown of PKCdelta expression by use of RNA interference (RNAi) reduced OSM-mediated osteogenic differentiation and decreased expression of Runx-2. These findings suggest that OSM differentially promotes osteogenesis in non-committed mesenchymal progenitors relative to other gp130 cytokines. This activity correlates with selective activation of PKCdelta in OSM-treated cells, indicating that OSM-induced osteogenesis and upregulation of osteogenic gene products require activity of PKCdelta.

Molecular pathways: IL11 as a tumor-promoting cytokine-translational implications for cancers.

Emerging evidence suggests that cytokines produced by inflammatory cells act as rheostats to link the degree of wounding and local inflammation to epithelial cell survival, proliferation, and metabolism that collectively underpin the repair response. Among these cytokines, the GP130 family, which encompasses, among others, IL6 and IL11, plays a major role in orchestrating these complex processes through the activation of the latent signal transducer and activator of transcription 3 (STAT3) in the epithelium. However, many of the molecular mechanisms that govern and ensure effective epithelial wound healing and regeneration renewal also promote tumorigenesis and the progression of established cancers. Accordingly, GP130 cytokines endow the inflammatory tumor microenvironment with a capacity to promote "cancer hallmark capabilities" of the malignant epithelium, while simultaneously suppressing the antitumor response of innate and adaptive immune cells. Here, we review some recent insights derived from genetic and therapeutic inhibition of the IL6/IL11-GP130-STAT3 signaling cascade in the context of preclinical mouse models of cancer, which are likely to have implications to other solid malignancies.

Achieving specificity in the glial cell response to the gp130 cytokines

Achieving specificity in the glial cell response to the gp130 cytokines

84: Differential responses to and regulation of gp130 cytokines in astrocytes versus microglia

The gp130 cytokines, including IL-6, IL-11, LIF and OSM, have important roles in neuroinflammation and neurodevelopment. However, the nature of any cell-specific responses of astrocytes and microglia to this family of cytokines and their molecular basis are not well understood. Here, the expression of the gp130 family cytokine receptors and subsequent signal pathway activation were examined in murine astrocytes and microglia in vitro . Astrocytes had high levels of OSMR mRNA and lower levels of IL-6R, LIFR and IL-11R mRNAs. In contrast, microglia expressed higher levels of IL-6R mRNA, similar levels of LIFR and IL-11R mRNAs, and no detectable OSMR mRNA. The OSMR protein was present in astrocytes but was undetectable in microglia. Conversely, the IL-6R protein was present in microglia but not detectable in astrocytes. In astrocytes, OSM induced STAT1 and STAT3 phosphorylation to a greater extent than hyperIL-6 (IL-6 linked to the soluble IL-6 receptor) and LIF. Conversely, hyperIL-6 and LIF but not OSM, induced phosphorylation of STAT1 and STAT3 in microglia. Upregulation of OSMR occurred in astrocytes, in response to a number of inflammatory mediators (e.g. lipo-polysaccharide) but remained undetectable in microglia. In contrast, the OSM mRNA was induced by the same inflammatory mediators in microglia but not astrocytes. Furthermore, the same inflammatory mediators also differentially induced other gp130 cytokines and their receptors between the two cell types. These findings show: (1) differences exist in the receptor expression utilized by the gp130 family of cytokines in astrocytes and microglia, (2) a molecular basis for the differential response to OSM by astrocytes versus microglia, and (3) a potential regulatory network exists between astrocytes and microglia in the central nervous system involving OSM and other gp130 cytokines.

Oncostatin M overexpression induces matrix deposition, STAT3 activation, and SMAD1 Dysregulation in lungs of fibrosis-resistant BALB/c mice

Adverse health outcomes in pulmonary fibrosis are associated with extracellular matrix (ECM) accumulation. Although transforming growth factor-β (TGF-β) has been reported to be an important regulator of fibrosis pathogenesis, TGF-β-independent pathways may also be involved. Here, we investigated responses of putative relatively fibrosis-resistant BALB/c mice to transient pulmonary overexpression of oncostatin M (OSM) using an adenovirus vector encoding OSM (AdOSM) and compared responses with the relatively fibrosis-prone C57Bl/6 strain. Interestingly, BALB/c mice showed similar ECM accumulation and collagen 1A1 and 3A1 mRNA elevation to C57Bl/6 mice 7 days after endotracheal administration of AdOSM. TGF-β1 mRNA levels and pSMAD2 signal were not regulated in either strain in total lung extracts. In contrast to C57Bl/6 mice, BALB/c mice lacked eosinophil, Th2 cytokine, and pro-inflammatory cytokine elevation in the broncholveolar space. OSM overexpression induced STAT3 activation and SMAD1/5/8 signaling suppression in lung from both mice strains, which was associated with a downregulation of BMPR2 and BMP ligands, and increased expression of the BMP antagonist gremlin. Although we also observed STAT3 activation and SMAD1/5/8 signaling suppression in mouse lung fibroblast cultures in vitro upon OSM stimulation, immunohistochemistry analyses indicated that the AdOSM-induced pSMAD1/5/8 signal suppression was primarily localized to the airway epithelium. Other gp130 cytokines including IL-6, LIF, CT-1, but not IL-31, also induced STAT3 activation and SMAD1/5/8 signaling suppression in C10 mouse lung epithelial cells and BEAS 2B bronchial epithelial cells, and we found that pharmacological inhibition of STAT3 activation reversed OSM-induced SMAD1/5/8 signaling suppression in vitro. The results demonstrate that OSM induces ECM accumulation in fibrosis-resistant BALB/c mouse lung in the absence of Th2 inflammation or TGF-β signaling, and highlight a dichotomy of STAT3 activation versus SMAD1 suppression in this process.

Key role of suppressor of cytokine signaling 3 in regulating gp130 cytokine-induced signaling and limiting chondrocyte responses during murine inflammatory arthritis.

To examine the impact of the gp130 cytokine family on murine articular cartilage and to explore a potential regulatory role of suppressor of cytokine signaling 3 (SOCS-3) in murine chondrocytes. In wild-type (WT) mouse chondrocytes, baseline receptor expression levels and gp130 cytokine-induced JAK/STAT signaling were determined by flow cytometry, and expression of SOCS-3 was assessed by quantitative polymerase chain reaction. The role of endogenous SOCS-3 was examined in cartilage explants and chondrocytes from mice with conditional deletion of Socs3 driven by the Col2a1 promoter in vitro (Socs3(Δ/Δcol2) ) and from mice during CD4+ T cell-dependent inflammatory monarthritis. Bone erosions in the murine joints were analyzed by micro-computed tomography. On chondrocytes from WT mice, gp130 and the oncostatin M (OSM) receptor were strongly expressed, whereas the transmembrane interleukin-6 (IL-6) receptor was expressed at much lower levels. Compared to other gp130 cytokines, OSM was the most potent activator of the JAK/STAT pathway and of SOCS-3 induction. Treatment of Socs3(Δ/Δcol2) mouse cartilage explants and chondrocytes with gp130 cytokines prolonged JAK/STAT signaling, enhanced cartilage degradation, increased the expression of Adamts4, Adamts5, and RANKL, and elevated the production of IL-6, granulocyte colony-stimulating factor, CXCL1, and CCL2. Socs3(Δ/Δcol2) mice developed exacerbated inflammation and joint damage in response to gp130 cytokine injections, and these histopathologic features were also observed in mice with inflammatory monarthritis. The results of this study highlight a key role for SOCS-3 in regulating chondrocyte responses during inflammatory arthritis. Within the gp130 cytokine family, OSM is a potent stimulus of chondrocyte responses, while IL-6 probably signals via trans-signaling. The gp130 cytokine-driven production of RANKL in chondrocytes may link chondrocyte activation and bone remodeling during inflammatory arthritis. Thus, these findings suggest that the inhibition of OSM might reduce the development and severity of structural joint damage during inflammatory arthritis.

Analysis of IL-6/gp130 family receptor expression reveals that in contrast to astroglia, microglia lack the oncostatin M receptor and functional responses to oncostatin M.

The interleukin (IL)-6/gp130 family of cytokines (e.g., IL-6, IL-11, leukemia inhibitory factor (LIF) and oncostatin M (OSM)) play important roles in the central nervous system (CNS) during neuroinflammation and neurodevelopment. However, little is known regarding the responses by astroglia and microglia to this family of cytokines. Here the expression of the IL-6/gp130 cytokine receptors and subsequent signal pathway activation was examined in murine astrocytes and microglia in vitro. Astrocytes had high levels of OSMR mRNA while lower levels of IL-6R, LIFR and IL-11R mRNAs were also present. In comparison, in microglia there was no detectable OSMR mRNA, higher levels of IL-6R mRNA and lower levels of the LIFR and IL-11R mRNAs. The OSMR protein was present in astrocytes but was undetectable in microglia. Conversely, the IL-6R protein was present in microglia but not detectable in astrocytes. In astrocytes but not microglia, phosphorylation of STAT1 and STAT3 occurred in response to OSM, whereas both microglia and astrocytes responded to hyper-IL-6 (IL-6 linked to the soluble IL-6 receptor). Finally, in both microglia and astrocytes, OSM failed to activate NFκB or induce iNOS and nitrite production. We conclude: (1) notable differences exist in the expression of receptors utilized by the IL-6/gp130 family of cytokines in astrocytes and microglia, and (2) the findings provide a molecular basis for the differential response to OSM by astrocytes versus microglia and demonstrate a fundamental means for achieving cellular specificity in the response of these glial cells to this cytokine.

Prostaglandin F2α Inhibits Adipogenesis Via an Autocrine‐Mediated Interleukin‐11/Glycoprotein 130/STAT1‐Dependent Signaling Cascade

Prostaglandin F2α (PGF2α) is a potent inhibitor of adipocyte differentiation in vitro, that has also recently been implicated in the regulation of the adipogenic process in vivo, by opposing adipose tissue accretion and the subsequent development of obesity and its attendant metabolic consequences. In previous studies, we have demonstrated that PGF2α inhibits adipocyte differentiation by means of a calcium-dependent signaling pathway that is critically dependent upon the activity of the calcineurin phosphatase. In the current study, we have now extended these findings to further elucidate the mechanism by which the PGF2α/calcineurin-pathway inhibits the adipogenic process. We now report that the IL-11 cytokine, a member of the gp130 cytokine co-receptor-related family, is a downstream transcriptional target of this pathway in 3T3-L1 preadipocytes and is actively secreted in differentiating cells in response to PGF2α stimulation. Using a combined shRNA and dominant-negative receptor mutant approach, we provide evidence that IL-11/gp130-signaling is required to mediate the inhibitory effects of PGF2α on adipogenesis. Moreover, by taking advantage of a well-characterized panel of chimeric gp130 mutant receptors, we demonstrate that gp130 signaling is sufficient to inhibit adipocyte differentiation and specifically requires the activation of the STAT1 transcription factor. Conversely, we find that depleting endogenous STAT1 levels rescues adipogenesis in the presence of both IL-11/gp130 signaling and PGF2α. Collectively, our findings support a model in which PGF2α inhibits adipocyte differentiation by means of an IL-11 mediated autocrine negative feedback loop, that acts via gp130 to block adipogenesis through the essential actions of the STAT1 transcription factor.

Oncostatin M Is Produced in Adipose Tissue and Is Regulated in Conditions of Obesity and Type 2 Diabetes

Adipose tissue is a highly active endocrine organ that secretes many factors that affect other tissues and whole-body metabolism. Adipocytes are responsive to several glycoprotein 130 (gp130) cytokines, some of which have been targeted as potential antiobesity therapeutics. Oncostatin M (OSM) is a gp130 family member known to inhibit adipocyte differentiation in vitro, but its effects on other adipocyte properties are not characterized. The expression of OSM in white adipose tissue (WAT) has not been evaluated in the context of obesity. Thus, our objective was to examine the expression of adipose tissue OSM in obese animals and humans. OSM expression was examined in adipose tissues from mice with diet-induced and genetic obesity and in obese humans as well as in fractionated adipose tissue from mice. Murine adipocytes were used to examine OSM receptor expression and the effects of OSM on adipocytes, including the secretion of factors such as plasminogen activator inhibitor 1 and IL-6, which are implicated in metabolic diseases. OSM expression is increased in rodent and human obesity/type 2 diabetes mellitus. In humans, OSM levels correlate with body weight and insulin and are inversely correlated with glucose disposal rate as measured by hyperinsulinemic-euglycemic clamp. OSM is not produced from the adipocytes in WAT but derives from cells in the stromovascular fraction, including F4/80(+) macrophages. The specific receptor of OSM, OSM receptor-β, is expressed in adipocytes and adipose tissue and increased in both rodent models of obesity examined. OSM acts on adipocytes to induce the expression and secretion of plasminogen activator inhibitor 1 and IL-6. These data indicate that WAT macrophages are a source of OSM and that OSM levels are significantly induced in murine and human obesity/type 2 diabetes mellitus. These studies suggest that OSM produced from immune cells in WAT acts in a paracrine manner on adipocytes to promote a proinflammatory phenotype in adipose tissue.

Cell-Intrinsic IL-27 and gp130 Cytokine Receptor Signaling Regulates Virus-Specific CD4+ T Cell Responses and Viral Control during Chronic Infection

The outcome of chronic viral infections, which affect millions of people worldwide, is greatly dependent on CD4⁺ T cells. Here we showed that T cell-specific ablation of the common interleukin-6 (IL-6) family receptor, gp130, profoundly compromised virus-specific CD4⁺ T cell survival, T follicular helper responses, and IL-21 production at late stages of chronic lymphocytic choriomeningitis virus (LCMV) infection. These effects were cell intrinsic for CD4⁺ T cells and were accompanied by a reduction of CD8⁺ T cells, antibodies, and a severe failure in viral control. We identified IL-27 as a gp130 cytokine that promoted antiviral CD4⁺ T cell accumulation in vivo and that rapidly induced IL-21 ex vivo. Furthermore, IL-27R was critical for control of persistent LCMV in vivo. These results reveal that gp130 cytokines (particularly IL-27) are key regulators of CD4⁺ T cell responses during an established chronic viral infection, empowering both humoral and cytotoxic immunity.

283: Suppression of SMAD-1 signaling pathway in mouse lung tissue remodelling by oncostatin M

Introduction Abnormal remodeling of the extracellular matrix (ECM) in lung tissue marks the pathology and compromises lung function in diseases such as pulmonary fibrosis and severe asthma. Various cytokine networks, including TGF-beta and gp130 cytokines, have been shown to modulate the ECM. More recent work has suggested a protective role for bone morphogenetic proteins (BMP) in pulmonary fibrosis. We have previously shown that over-expression of Oncostatin M (OSM), one member of the gp130 cytokine family, induces ECM remodeling in mouse lung that remains evident in SMAD3−/− and IL-6−/− mice. Here we examine the regulation of BMP/SMAD1 signaling pathways upon transient pulmonary over-expression of OSM. Methods: C57Bl/6 mice were intubated with adenovirus vector encoding OSM (AdOSM) to induce transient pulmonary over-expression for 7 days. Lungs were processed for histology, immunohistochemistry, RNA analysis for ECM proteins (collagen) and BMP-associated proteins (BMP-2, BMP-4, BMP-7, gremlin), or for protein analysis by immunoblot for (activated) pSTAT3, pSMAD1/5/8 and BMPReceptor2. Results: AdOSM induced ECM remodeling as indicated by increased parenchymal collagen (PSR stain), coll1a1 and coll1a2 mRNA levels. Immunoblots of signaling responses in total lung homogenates showed increased levels of pSTAT3, but decreased levels of pSMAD1/5/8 and BMPR2 in AdOSM-treated mice. Immunohistochemistry showed a marked reduction of pSMAD1/5/8 detected in airway epithelial cells due to AdOSM, whereas pSTAT3 was up-regulated in airway epithelial and other cells. Levels of mRNA of BMP-2 and BMP-4 were reduced whereas gremlin mRNA was increased in total lungs of AdOSM-treated compared to control (AdDl70) mice. Conclusions: Transient over-expression of OSM induces rapid ECM remodeling in mouse lungs and caused marked suppression of BMP-2/4 mRNA, BMPR2 and pSMAD1 signaling. Such effects would decrease the putative protective function of BMPs in lung fibrosis. Thus OSM-induced suppression of the SMAD1 signaling, in context of STAT3 activation, may reflect a novel pathway that contributes to lung ECM remodeling. This work was supported by the Canadian Institutes for Health Research.