Oncostatin M: signal transduction and biological activity

Spleen derived monocytes regulate pulmonary vascular permeability in Hepatopulmonary syndrome through the OSM-FGF/FGFR1 signaling

Hepatopulmonary syndrome (HPS) is a serious pulmonary complication in the advanced stage of liver disease. The occurrence of pulmonary edema in HPS patients is life-threatening. Increased pulmonary vascular permeability is an important mechanism leading to pulmonary edema, and endothelial glycocalyx (EG) is a barrier that maintains stable vascular permeability. However, in HPS, whether the pulmonary vascular EG changes and its regulatory mechanism are still unclear. Spleen derived monocytes are involved in the pathogenesis of HPS. However, whether they regulate the pulmonary vascular permeability in HPS patients or rats and what is the mechanism is still unclear. Healthy volunteers and HPS patients with splenectomy or not were enrolled in this study. We found that the respiration of HPS patients was significantly improved in response to splenectomy, while the EG degradation and pulmonary edema were aggravated. In addition, HPS patients expressed higher levels of oncostatin M (OSM) and fibroblast growth factor (FGF). Subsequently, the co-culture system of monocytes and human umbilical vein endothelial cells (HUVECs) was constructed. It was found that monocytes secreted OSM and activated the FGF/FGFR1 signaling pathway in HUVECs. Then, an HPS rat model was constructed by common bile duct ligation (CBDL) for in vivo verification. HPS rats were intravenously injected with OSM recombinant protein and/or TNF-α into the rats via tail vein 30 min before CBDL. The results showed that the respiration of HPS rats was improved after splenectomy, while the degradation of EG in pulmonary vessels and vascular permeability were increased, and pulmonary edema was aggravated. Moreover, the expression of OSM and FGF was upregulated in HPS rats, while both were downregulated after splenectomy. Intravenous injection of exogenous OSM eliminated the effect of splenectomy on FGF and improved EG degradation. It can be seen that during HPS, spleen-derived monocytes secrete OSM to promote pulmonary vascular EG remodeling by activating the FGF/FGFR1 pathway, thereby maintaining stable vascular permeability, and diminishing pulmonary edema. This study provides a promising therapeutic target for the treatment of HPS.

Liver organoid culture methods

Organoids, three-dimensional structures cultured in vitro, can recapitulate the microenvironment, complex architecture, and cellular functions of in vivo organs or tissues. In recent decades, liver organoids have been developed rapidly, and their applications in biomedicine, such as drug screening, disease modeling, and regenerative medicine, have been widely recognized. However, the lack of repeatability and consistency, including the lack of standardized culture conditions, has been a major obstacle to the development and clinical application of liver organoids. It is time-consuming for researchers to identify an appropriate medium component scheme, and the usage of some ingredients remains controversial. In this review, we summarized and compared different methods for liver organoid cultivation that have been published in recent years, focusing on controversial medium components and discussing their advantages and drawbacks. We aimed to provide an effective reference for the development and standardization of liver organoid cultivation.

Methylmercury directly modifies the 105th cysteine residue in oncostatin M to promote binding to tumor necrosis factor receptor 3 and inhibit cell growth

We previously found that methylmercury induces expression of oncostatin M (OSM), which is released extracellularly and binds to tumor necrosis factor receptor 3 (TNFR3), possibly enhancing its own toxicity. However, the mechanism by which methylmercury causes OSM to bind to TNFR3 rather than to its known receptors, OSM receptor and LIFR, is unknown. In this study, we aimed to elucidate the effect of methylmercury modification of cysteine residues in OSM on binding to TNFR3. Immunostaining of TNFR3-V5-expressing cells suggested that methylmercury promoted binding of OSM to TNFR3 on the cell membrane. In an in vitro binding assay, OSM directly bound to the extracellular domain of TNFR3, and this binding was promoted by methylmercury. Additionally, the formation of a disulfide bond in the OSM molecule was essential for the binding of both proteins, and LC/MS analysis revealed that methylmercury directly modified the 105th cysteine residue (Cys105) in OSM. Next, mutant OSM, in which Cys105 was replaced by serine or methionine, increased the binding to TNFR3, and a similar effect was observed in immunoprecipitation using cultured cells. Furthermore, cell proliferation was inhibited by treatment with Cys105 mutant OSMs compared with wildtype OSM, and this effect was cancelled by TNFR3 knockdown. In conclusion, we revealed a novel mechanism of methylmercury toxicity, in which methylmercury directly modifies Cys105 in OSM, thereby inhibiting cell proliferation via promoting binding to TNFR3. This indicates a chemical disruption in the interaction between the ligand and the receptor is a part of methylmercury toxicity.

Oncostatin M Improves Cutaneous Wound Re-Epithelialization and Is Deficient under Diabetic Conditions

Impaired re-epithelialization characterized by hyperkeratotic nonmigratory wound epithelium is a hallmark of nonhealing diabetic wounds. In chronic wounds, the copious release of oncostatin M (OSM) from wound macrophages is evident. OSM is a potent keratinocyte (KC) activator. This work sought to understand the signal transduction pathway responsible for wound re-epithelialization, the primary mechanism underlying wound closure. Daily topical treatment of full-thickness excisional wounds of C57BL/6 mice with recombinant murine OSM improved wound re-epithelialization and accelerated wound closure by bolstering KC proliferation and migration. OSM activated the Jak-signal transducer and activator of transcription pathway as manifested by signal transducer and activator of transcription 3 phosphorylation. Such signal transduction in the human KC induced TP63, the master regulator of KC function. Elevated TP63 induced ITGB1, a known effector of KC migration. In diabetic wounds, OSM was more abundant than the level in nondiabetic wounds. However, in diabetic wounds, OSM activity was compromised by glycation. Aminoguanidine, a deglycation agent, rescued the compromised KC migration caused by glycated OSM. Finally, topical application of recombinant OSM improved KC migration and accelerated wound closure in db/db mice. This work recognizes that despite its abundance at the wound site, OSM is inactivated by glycation, and topical delivery of exogenous OSM is likely to be productive in accelerating diabetic wound closure.

Oncostatin M is overexpressed in NASH ‐related hepatocellular carcinoma and promotes cancer cell invasiveness and angiogenesis

Oncostatin M (OSM) is a pleiotropic cytokine of the interleukin (IL)‐6 family that contributes to the progression of chronic liver disease. Here we investigated the role of OSM in the development and progression of hepatocellular carcinoma (HCC) in non‐alcoholic fatty liver disease (NAFLD)/non‐alcoholic steatohepatitis (NASH). The role of OSM was investigated in (1) selected cohorts of NAFLD/NASH HCC patients, (2) liver cancer cells exposed to human recombinant OSM or stably transfected to overexpress human OSM, (3) murine HCC xenografts, and (4) a murine NASH‐related model of hepatic carcinogenesis. OSM was found to be selectively overexpressed in HCC cells of NAFLD/NASH patients, depending on tumor grade. OSM serum levels, barely detectable in patients with simple steatosis or NASH, were increased in patients with cirrhosis and more evident in those carrying HCC. In this latter group, OSM serum levels were significantly higher in the subjects with intermediate/advanced HCCs and correlated with poor survival. Cell culture experiments indicated that OSM upregulation in hepatic cancer cells contributes to HCC progression by inducing epithelial‐to‐mesenchymal transition and increased invasiveness of cancer cells as well as by inducing angiogenesis, which is of critical relevance. In murine xenografts, OSM overexpression was associated with slower tumor growth but an increased rate of lung metastases. Overexpression of OSM and its positive correlation with the angiogenic switch were also confirmed in a murine model of NAFLD/NASH‐related hepatocarcinogenesis. Consistent with this, analysis of liver specimens from human NASH‐related HCCs with vascular invasion showed that OSM was expressed by liver cancer cells invading hepatic vessels. In conclusion, OSM upregulation appears to be a specific feature of HCC arising on a NAFLD/NASH background, and it correlates with clinical parameters and disease outcome. Our data highlight a novel pro‐carcinogenic contribution for OSM in NAFLD/NASH, suggesting a role of this factor as a prognostic marker and a putative potential target for therapy. © 2022 The Authors. The Journal of Pathology published by John Wiley & Sons Ltd on behalf of The Pathological Society of Great Britain and Ireland.

Long non-coding RNA Pvt1 modulates the pathological cardiac hypertrophy via miR-196b-mediated OSMR regulation

Cardiac hypertrophy is the uppermost risk factor for the development of heart failure, leading to irreversible cardiac structural remodeling and sudden death. As a major mediator of cardiac remodeling, oncostatin M (OSM) and its receptor, OSMR, attract plenty of interest. Recent studies have demonstrated key effects of noncoding RNAs on myocardial remodeling. However, whether noncoding RNAs that regulate the expression of OSMR would regulate the process of remodeling remain unclear. Herein, we observed that long noncoding RNA (lncRNA) Pvt1 expression showed to be significantly elicited by aortic banding (AB) operation in vivo and by angiotensin (Ang II) treatment in vitro. Pvt1 knockdown significantly attenuated the myocardial hypertrophy caused by pressure overload within rats and the cardiac myocyte hypertrophy caused by Ang II in vitro. Moreover, Pvt1 knockdown also decreased cellular myomesin and B-raf, which was involved in OSM function in cardiac remodeling. Based on online tools prediction, miR-196b may simultaneously target Pvt1 and OSMR 3' untranslated region (UTR). In rat H9c2 cells and primary cardiac myocyte, Pvt1 and miR-196b exerted negative regulatory effects on each other and miR-196b negatively regulated OSMR expression. Pvt1 directly targeted miR-196b to relieve miR-196b-induced OSMR suppression via acting as a competing endogenous RNA (ceRNA). Moreover, the effect of miR-196b suppression upon the B-raf was opposite to Pvt1 knockdown, and miR-196b suppression might significantly attenuate the effect of Pvt1 knockdown. In summary, Pvt1/miR-196b axis modulating cardiomyocyte hypertrophy and remodeling via OSMR. Our findings provide a rationale for further studies on the potential therapeutic benefits of Pvt1 function and mechanism in cardiac and cardiomyocyte hypertrophy by a lncRNA-miRNA-mRNA network.

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.

The Role of Adipokines in Breast Cancer: Current Evidence and Perspectives

PURPOSE

The current review shows evidence for the role of adipokines in breast cancer (BC) pathogenesis summarizing the mechanisms underlying the association between adipokines and breast malignancy. Special emphasis is given also on intriguing insights into the relationship between obesity and BC as well as on the role of novel adipokines in BC development.

RECENT FINDINGS

Recent evidence has underscored the role of the triad of obesity, insulin resistance, and adipokines in postmenopausal BC. Adipokines exert independent and joint effects on activation of major intracellular signal networks implicated in BC cell proliferation, growth, survival, invasion, and metastasis, particularly in the context of obesity, considered a systemic endocrine dysfunction characterized by chronic inflammation. To date, more than 10 adipokines have been linked to BC, and this catalog is continuously increasing. The majority of circulating adipokines, such as leptin, resistin, visfatin, apelin, lipocalin 2, osteopontin, and oncostatin M, is elevated in BC, while some adipokines such as adiponectin and irisin (adipo-myokine) are generally decreased in BC and considered protective against breast carcinogenesis. Further evidence from basic and translational research is necessary to delineate the ontological role of adipokines and their interplay in BC pathogenesis. More large-scale clinical and longitudinal studies are awaited to assess their clinical utility in BC prognosis and follow-up. Finally, novel more effective and safer adipokine-centered therapeutic strategies could pave the way for targeted oncotherapy.

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.

A Subset of TREM2+ Dermal Macrophages Secretes Oncostatin M to Maintain Hair Follicle Stem Cell Quiescence and Inhibit Hair Growth

Hair growth can be induced from resting mouse hair follicles by topical application of JAK inhibitors, suggesting that JAK-STAT signaling is required for maintaining hair follicle stem cells (HFSCs) in a quiescent state. Here, we show that Oncostatin M (OSM), an IL-6 family cytokine, negatively regulates hair growth by signaling through JAK-STAT5 to maintain HFSC quiescence. Genetic deletion of the OSM receptor or STAT5 can induce premature HFSC activation, suggesting that the resting telogen stage is actively maintained by the hair follicle niche. Single-cell RNA sequencing revealed that the OSM source is not intrinsic to the hair follicle itself and is instead a subset of TREM2⁺ macrophages that is enriched within the resting follicle and deceases immediately prior to HFSC activation. In vivo inhibition of macrophage function was sufficient to induce HFSC proliferation and hair cycle induction. Together these results clarify how JAK-STAT signaling actively inhibits hair growth.

AXIN1 in Plasma or Serum Is a Potential New Biomarker for Endometriosis

Although endometriosis is considered an inflammatory disease, no reliable diagnostic biomarkers exist for use in clinical practice. The aim was to investigate the inflammatory profile in endometriosis using an exploratory approach of inflammation-related proteins. Patients with laparoscopy-verified endometriosis (N = 172), women with microscopic colitis (N = 50), healthy controls (N = 31), and age-matched controls from the general population (N = 100) were enrolled and questionnaires regarding socioeconomic factors, lifestyle habits, and medical history were completed. Sera from patients and healthy controls were analyzed for 92 inflammatory biomarkers using Proximity Extension Assay technology (PEA). Plasma AXIN1 levels were analyzed in patients with endometriosis and controls from the general population by ELISA. General linear model adjusted for age, Mann–Whitney U-test, and principal component analysis (PCA) were used for statistical calculations. Serum levels of AXIN1 and ST1A1 were increased in endometriosis compared with MC (p < 0.001) and healthy controls (p = 0.001), whereas CXCL9 levels were decreased. Plasma levels of AXIN1 were elevated in endometriosis compared with age-matched controls from the general population (30.0 (17.0–38.0) pg/mL vs. 19.5 (15.0–28.0) pg/mL, p < 0.001). PCA analysis identified four clusters of proteins, where one cluster differed between endometriosis and controls, with strong correlations for AXIN1 and ST1A1. Plasma/serum AXIN1 is an interesting biomarker to be further evaluated in endometriosis.

Megakaryocyte Contribution to Bone Marrow Fibrosis: many Arrows in the Quiver

In Primary Myelofibrosis (PMF), megakaryocyte dysplasia/hyperplasia determines the release of inflammatory cytokines that, in turn, stimulate stromal cells and induce bone marrow fibrosis. The pathogenic mechanism and the cells responsible for progression to bone marrow fibrosis in PMF are not completely understood. This review article aims to provide an overview of the crucial role of megakaryocytes in myelofibrosis by discussing the role and the altered secretion of megakaryocyte-derived soluble factors, enzymes and extracellular matrices that are known to induce bone marrow fibrosis.

Oncostatin M suppresses metastasis of lung adenocarcinoma by inhibiting SLUG expression through coordination of STATs and PIASs signalings

Oncostatin M (OSM) is linked with multiple biological responses including growth and differentiation. Previous reports showed inhibitory effects of OSM in tumor progression while others showed promoting effects. The dual role of OSM in the development of various cancers is still unclear. We previously described OSM-mediated SLUG suppression, leading to repressed metastasis of lung adenocarcinoma (LAC) cells. However, the underlying mechanism remains elusive. Here, we showed that OSM suppresses SLUG express in LAC cells through a STAT1-dependent transcriptional inhibition. Knockdown of STAT1 reversed the OSM-suppressed SLUG expression and rescued the OSM-mediated inhibition of cell proliferation, migration, and invasion in vitro, as well as pulmonary metastasis in vivo. STAT1 suppressed SLUG transcription through binding to its promoter region in response to OSM. Furthermore, PIAS4, a co-repressor of STAT, and HDAC1 were able to bind to STAT1 on SLUG promoter region, resulting in reduced H3K9 acetylation and suppressed SLUG expression upon OSM treatment. In contrast, PIAS3 bound to activated STAT3, another effector of OSM, in response to OSM and blocked the binding of STAT3 to SLUG promoter region, preventing STAT3-dependent activation of SLUG transcription. Our findings suggested that OSM suppresses SLUG expression and tumor metastasis of LAC through inducing the inhibitory effect of the STAT1-dependent pathway and suppressing the activating effect of STAT3-dependent signaling. These results can serve as a scientific basis for the potential therapeutic intervention of OSM in cancer cells.

Oncostatin M upregulates HIF-1α in breast tumor associated macrophages independent of intracellular oxygen concentration

AIMS

HIF is an important transcription-regulator for adaptation to cellular stress in cells of myeloid origin. Classically, expression and activity of HIF1-α is regulated by oxygen-concentration within cell. However, there exists an alternative regulatory mechanism affecting HIF1-α levels independent of oxygen concentration particularly in inflammatory cells like macrophages. Here we report the mechanism of HIF1-α upregulation in TAMs by Oncostatin-M (OSM) independent of cellular oxygen concentration.

MAIN METHODS

THP-1 derived macrophages were treated with OSM. HIF1-α levels and interaction with pVHL were evaluated via immunoblot-analysis and Co-immunoprecipitation. Translocation of HIF1-α to nucleus was visualized using confocal-microscopy. Fold change in mRNA levels of ARG-1 and COX-2 was analyzed using RT-PCR.

KEY FINDINGS

Current study demonstrates that OSM treatment to TAMs led to an increased expression of HIF1-α under normoxic conditions via activation of mTORC2. This HIF1-α upregulation was dependent on both de novo synthesis of HIF1-α and its enhanced stability due to disruption of its binding to pVHL. Furthermore, we evaluated that OSM not only enhances the expression of HIF1-α but also increases its localization to nucleus where it acts as a transcription factor regulating expression of genes like ARG-1 and COX-2.

SIGNIFICANCE

Inflammation is a critical hallmark of cancer as tumor microenvironment is largely infiltrated with macrophages. These tumor associated macrophages (TAMs) display a M2 skewed phenotype. Many target genes of TAMs are HIF1-α responsive. These TAMs are involved in tumor progression, metastasis and angiogenesis. Targeting of HIF1-α/OSM can lead to devising of better therapeutic strategy against cancer.

Carbon nanohorns allow acceleration of osteoblast differentiation via macrophage activation

Carbon nanohorns (CNHs), formed by a rolled graphene structure and terminating in a cone, are promising nanomaterials for the development of a variety of biological applications. Here we demonstrate that alkaline phosphatase activity is dramatically increased by coculture of human monocyte derived macrophages (hMDMs) and human mesenchymal stem cells (hMSCs) in the presence of CNHs. CNHs were mainly localized in the lysosome of macrophages more than in hMSCs during coculturing. At the same time, the amount of Oncostatin M (OSM) in the supernatant was also increased during incubation with CNHs. Oncostatin M (OSM) from activated macrophage has been reported to induce osteoblast differentiation and matrix mineralization through STAT3. These results suggest that the macrophages engulfed CNHs and accelerated the differentiation of mesenchymal stem cells into the osteoblast via OSM release. We expect that the proof-of-concept on the osteoblast differentiation capacity by CNHs will allow future studies focused on CNHs as ideal therapeutic materials for bone regeneration.

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.

Notch3/Akt signaling contributes to OSM-induced protection against cardiac ischemia/reperfusion injury

Oncostatin M (OSM) exhibits many unique biological activities by activating the Oβ receptor. However, its role in myocardial ischemia/reperfusion injury (I/R injury) in mice remains unknown. We investigated whether Notch3/Akt signaling is involved in the regulation of OSM-induced protection against cardiac I/R injury. The effects of OSM were assessed in mice that underwent myocardial I/R injury by OSM treatment or by genetic deficiency of the OSM receptor Oβ. We investigated its effects on cardiomyocyte apoptosis and mitochondrial biogenesis and whether Notch3/Akt signaling was involved in the regulation of OSM-induced protection against cardiac I/R injury. The mice underwent 30 min of ischemia followed by 3 h of reperfusion and were randomized to be treated with Notch3 siRNA (siNotch3) or lentivirus carrying Notch3 cDNA (Notch3) 72 h before coronary artery ligation. Myocardial infarct size, cardiac function, cardiomyocyte apoptosis and mitochondria morphology in mice that underwent cardiac I/R injury were compared between groups. OSM alleviated cardiac I/R injury by inhibiting cardiomyocyte apoptosis through promotion of Notch3 production, thus activating the PI3K/Akt pathway. OSM enhanced mitochondrial biogenesis and mitochondrial function in mice subjected to cardiac I/R injury. In contrast, OSM receptor Oβ knock out exacerbated cardiac I/R injury, decreased Notch3 production, enhanced cardiomyocyte apoptosis, and impaired mitochondrial biogenesis in cardiac I/R injured mice. The mechanism of OSM on cardiac I/R injury is partly mediated by the Notch3/Akt pathway. These results suggest a novel role of Notch3/Akt signaling that contributes to OSM-induced protection against cardiac I/R injury.

Role of the interleukin 6 receptor family in epithelial ovarian cancer and its clinical implications

Ovarian cancer is the most lethal gynecological malignancy, with few effective treatment options in most cases. Therefore, understanding the biology of ovarian cancer remains an important area of research in order to improve clinical outcomes. Cytokine receptor signaling through the Janus kinase-signal transducer and activator of transcription (JAK-STAT) pathway is an essential component of normal development and homeostasis. However, numerous studies have implicated perturbation of this pathway in a range of cancers. In particular, members of the IL-6R family acting via the downstream STAT3 transcription factor play an important role in a number of solid tumors - including ovarian cancer - by altering the expression of target genes that impact on key phenotypes. This has led to the development of specific inhibitors of this pathway which are being used in combination with standard chemotherapeutic agents. This review focuses on the role of IL-6R family members in the etiology of epithelial ovarian cancer, and the application of therapies specifically targeting IL-6R signaling in this disease setting.

Regulation of monocyte differentiation by specific signaling modules and associated transcription factor networks

Monocyte/macrophages are important players in orchestrating the immune response as well as connecting innate and adaptive immunity. Myelopoiesis and monopoiesis are characterized by the interplay between expansion of stem/progenitor cells and progression towards further developed (myelo)monocytic phenotypes. In response to a variety of differentiation-inducing stimuli, various prominent signaling pathways are activated. Subsequently, specific transcription factors are induced, regulating cell proliferation and maturation. This review article focuses on the integration of signaling modules and transcriptional networks involved in the determination of monocytic differentiation.

Oncostatin M stimulates cell migration and proliferation by down-regulating E-cadherin in HTR8/SVneo cell line through STAT3 activation

BACKGROUND

During the first trimester of pregnancy, trophoblastic E-cadherin expression is down-regulated, thereby allowing extravillous trophoblasts (EVTs) to acquire the potential for migration and invasiveness. The aim of the present study was to investigate the role of OSM on the migration and proliferation of EVT cell line HTR8/SVneo with regard to its effects on the expression of E-cadherin and STAT3 activation.

METHODS

We investigated the effects of OSM on RNA and protein expression of E-cadherin by real time RT-PCR analyses, western blotting, and indirect immunofluorescence staining in HTR8/SVneo cells, as well as the effects on cell migration and proliferation. The selective signal transducer and activator of transcription (STAT)3 inhibitor, stattic, and STAT3 siRNA were used to investigate STAT3 activation by OSM.

RESULTS

OSM significantly reduced RNA and protein expression of E-cadherin. Indirect immunofluorescence staining of HTR8/SVneo cells also revealed the down-regulation of E-cadherin, compared with the controls. OSM-stimulated cell migration was attenuated by anti-gp130 antibodies. OSM-induced STAT3 phosphorylation, and the down-regulation of E-cadherin by OSM treatment was restored by stattic and STAT3 siRNA. In addition, OSM-stimulated migration and proliferation were significantly suppressed by STAT3 inhibition.

CONCLUSIONS

This study suggests that OSM stimulates the migration and proliferation of EVTs during the first trimester of pregnancy through the down-regulation of E-cadherin. In addition, this study suggests that the effects of OSM on migration and proliferation are related to STAT3 activation, which is important in trophoblast invasiveness.

Enhancement of placenta growth factor expression by oncostatin M in human rheumatoid arthritis synovial fibroblasts

Oncostatin M (OSM) belongs to IL-6 subfamily and is mostly produced by T lymphocytes. High levels of OSM are detected in the pannus of rheumatoid arthritis (RA) patients and it may arouse the inflammation responses in joints and eventually leads to bone erosion. Placenta growth factor (PLGF) is an angiogenic factor and highly homologous with vascular endothelial growth factor (VEGF). It has been recently reported that PLGF is highly expressed in synovial tissue and enhances the production of proinflammatory cytokines including TNF-α and IL-6. Here, we demonstrated that OSM increased mRNA and protein levels of PLGF in a time- and concentration-dependent manner in RA synovial fibroblasts. Inhibitors of JAK3 and PI3K antagonized OSM-induced production of PLGF. OSM enhanced the phosphorylation of Tyr705-STAT3, Ser727-STAT3, Ser473-Akt, and increased the nuclear translocation of phosphorylated STAT3 time-dependently. Transfection of dominant negative Akt or application of PI3K inhibitorLY294002 significantly inhibited p-Tyr705-STAT3, p-Ser727-STAT3, and PLGF expression, indicating that Akt is involved in JAK3/STAT3/PLGF signaling cascade. To further examine whether STAT3 binds to the promoter region of PLGF, Chip assay was used and it was found that OSM could bind with PLGF promoter, which was inhibited by JAK3 and PI3K inhibitors. Accumulation of PLGF in the pannus may contribute to the inflammation, angiogenesis and joints destruction in RA patients. These findings demonstrated the important role of OSM in the pathology network of RA and provided novel therapeutic drug targets for RA treatment.

Stat3-coordinated Lin-28-let-7-HMGA2 and miR-200-ZEB1 circuits initiate and maintain oncostatin M-driven epithelial-mesenchymal transition

Inflammation can act as a crucial mediator of epithelial-to-mesenchymal transition (EMT). In this study, we show that oncostatin M (OSM) is expressed in an autocrine/paracrine fashion in invasive breast carcinoma. OSM stimulation promotes spontaneous lung metastasis of MCF-7 xenografts in nude mice. A conspicuous epigenetic transition was induced by OSM stimulation not only in breast cancer cell lines but also in MCF-7 xenografts in nude mice. The expression of miR-200 and let-7 family members in response to OSM stimulation was downregulated in a signal transducer and activator of transcription factor 3 (Stat3)-dependent manner, resulting in comprehensive alterations of the transcription factors and oncoproteins targeted by these microRNAs. Inhibition of Stat3 activation or the ectopic expression of let-7 and miR-200 effectively reversed the mesenchymal phenotype of breast cancer cells. Stat3 promotes the transcription of Lin-28 by directly binding to the Lin-28 promoter, resulting in the repression of let-7 expression and concomitant upregulation of the let-7 target, high-mobility group A protein 2 (HMGA2). Knock down of HMGA2 significantly impairs OSM-driven EMT. Our data indicate that downregulation of let-7 and miR-200 levels initiates and maintains OSM-induced EMT phenotypes, and HMGA2 acts as a master switch of OSM-induced EMT. These findings highlight the importance of Stat3-coordinated Lin-28B-let-7-HMGA2 and miR-200-ZEB1 circuits in the cytokine-mediated phenotypic reprogramming of breast cancer cells.

Potential of oncostatin M to accelerate diabetic wound healing

Oncostatin M (OSM) is a multifunctional cytokine found in a variety of pathologic conditions, which leads to excessive collagen deposition. Current studies demonstrate that OSM is also a mitogen for fibroblasts and has an anti-inflammatory action. It was therefore hypothesised that OSM may play an important role in healing of chronic wounds that usually involve decreased fibroblast function and persist in the inflammatory stage for a long time. In a previous in vitro study, the authors showed that OSM increased wound healing activities of diabetic dermal fibroblasts. However, wound healing in vivo is a complex process involving multiple factors. Thus, the purpose of this study was to evaluate the effect of OSM on diabetic wound healing in vivo. Five diabetic mice were used in this study. Four full-thickness round wounds were created on the back of each mouse (total 20 wounds). OSM was applied on the two left-side wounds (n = 10) and phosphate-buffered saline was applied on the two right-side wounds (n = 10). After 10 days, unhealed wound areas of the OSM and control groups were compared using the stereoimage optical topometer system. Also, epithelialisation, wound contraction and reduction in wound volume in each group were compared. The OSM-treated group showed superior results in all of the tested parameters. In particular, the unhealed wound area and the reduction in wound volume demonstrated statistically significant differences (P < 0·05). The results of this study indicate that topical application of OSM may have the potential to accelerate healing of diabetic wounds.

Prostaglandin E₂ induces oncostatin M expression in human chronic wound macrophages through Axl receptor tyrosine kinase pathway

Monocytes and macrophages (m) are plastic cells whose functions are governed by microenvironmental cues. Wound fluid bathing the wound tissue reflects the wound microenvironment. Current literature on wound inflammation is primarily based on the study of blood monocyte-derived macrophages, cells that have never been exposed to the wound microenvironment. We sought to compare pair-matched monocyte-derived macrophages with m isolated from chronic wounds of patients. Oncostatin M (OSM) was differentially overexpressed in pair-matched wound m. Both PGE₂ and its metabolite 13,14-dihydro-15-keto-PGE₂ (PGE-M) were abundant in wound fluid and induced OSM in wound-site m. Consistently, induction of OSM mRNA was observed in m isolated from PGE₂-enriched polyvinyl alcohol sponges implanted in murine wounds. Treatment of human THP-1 cell-derived m with PGE₂ or PGE-M caused dose-dependent induction of OSM. Characterization of the signal transduction pathways demonstrated the involvement of EP4 receptor and cAMP signaling. In human m, PGE₂ phosphorylated Axl, a receptor tyrosine kinase (RTK). Axl phosphorylation was also induced by a cAMP analogue demonstrating interplay between the cAMP and RTK pathways. PGE₂-dependent Axl phosphorylation led to AP-1 transactivation, which is directly implicated in inducible expression of OSM. Treatment of human m or mice excisional wounds with recombinant OSM resulted in an anti-inflammatory response as manifested by attenuated expression of endotoxin-induced TNF-α and IL-1β. OSM treatment also improved wound closure during the early inflammatory phase of healing. In summary, this work recognizes PGE₂ in the wound fluid as a potent inducer of m OSM, a cytokine with an anti-inflammatory role in cutaneous wound healing.

Identification of oncostatin M as a JAK2 V617F-dependent amplifier of cytokine production and bone marrow remodeling in myeloproliferative neoplasms

The JAK2 mutation V617F is detectable in a majority of patients with Philadelphia chromosome-negative myeloproliferative neoplasms (MPNs). Enforced expression of JAK2 V617F in mice induces myeloproliferation and bone marrow (BM) fibrosis, suggesting a causal role for the JAK2 mutant in the pathogenesis of MPNs. However, little is known about mechanisms and effector molecules contributing to JAK2 V617F-induced myeloproliferation and fibrosis. We show that JAK2 V617F promotes expression of oncostatin M (OSM) in neoplastic myeloid cells. Correspondingly, OSM mRNA levels were increased in the BM of patients with MPNs (median 287% of ABL, range 22-1450%) compared to control patients (median 59% of ABL, range 12-264%; P < 0.0001). OSM secreted by JAK2 V617F+ cells stimulated growth of fibroblasts and microvascular endothelial cells and induced the production of angiogenic and profibrogenic cytokines (HGF, VEGF, and SDF-1) in BM fibroblasts. All effects of MPN cell-derived OSM were blocked by a neutralizing anti-OSM antibody, whereas the production of OSM in MPN cells was suppressed by a pharmacologic JAK2 inhibitor or RNAi-mediated knockdown of JAK2. In summary, JAK2 V617F-mediated up-regulation of OSM may contribute to fibrosis, neoangiogenesis, and the cytokine storm observed in MPNs, suggesting that OSM might serve as a novel therapeutic target molecule in these neoplasms.

Strengthening insights into host responses to mastitis infection in ruminants by combining heterogeneous microarray data sources

Background

Gene expression profiling studies of mastitis in ruminants have provided key but fragmented knowledge for the understanding of the disease. A systematic combination of different expression profiling studies via meta-analysis techniques has the potential to test the extensibility of conclusions based on single studies. Using the program Pointillist, we performed meta-analysis of transcription-profiling data from six independent studies of infections with mammary gland pathogens, including samples from cattle challenged in vivo with S. aureus, E. coli, and S. uberis, samples from goats challenged in vivo with S. aureus, as well as cattle macrophages and ovine dendritic cells infected in vitro with S. aureus. We combined different time points from those studies, testing different responses to mastitis infection: overall (common signature), early stage, late stage, and cattle-specific.

Results

Ingenuity Pathway Analysis of affected genes showed that the four meta-analysis combinations share biological functions and pathways (e.g. protein ubiquitination and polyamine regulation) which are intrinsic to the general disease response. In the overall response, pathways related to immune response and inflammation, as well as biological functions related to lipid metabolism were altered. This latter observation is consistent with the milk fat content depression commonly observed during mastitis infection. Complementarities between early and late stage responses were found, with a prominence of metabolic and stress signals in the early stage and of the immune response related to the lipid metabolism in the late stage; both mechanisms apparently modulated by few genes, including XBP1 and SREBF1.

The cattle-specific response was characterized by alteration of the immune response and by modification of lipid metabolism. Comparison of E. coli and S. aureus infections in cattle in vivo revealed that affected genes showing opposite regulation had the same altered biological functions and provided evidence that E. coli caused a stronger host response.

Conclusions

This meta-analysis approach reinforces previous findings but also reveals several novel themes, including the involvement of genes, biological functions, and pathways that were not identified in individual studies. As such, it provides an interesting proof of principle for future studies combining information from diverse heterogeneous sources.

Directed hepatic differentiation from embryonic stem cells

The liver is the largest internal organ in mammals, and is important for the maintenance of normal physiological functions of other tissues and organs. Hepatitis, cirrhosis, liver cancer and other chronic liver diseases are serious threats to human health, and these problems are compounded by a scarcity of liver donors for transplantation therapies. Directed differentiation of embryonic stem cells to liver cells is a promising strategy for obtaining hepatocytes that can be used for cell transplantation. In vitro hepatocyte differentiation of embryonic stem cells requires a profound understanding of normal development during embryonic hepatogenesis. Here we provide a simple description of hepatogenesis in vivo and discuss directed differentiation of embryonic stem cells into hepatocytes in vitro.

Identification of oncostatin M as a STAT5-dependent mediator of bone marrow remodeling in KIT D816V-positive systemic mastocytosis

Systemic mastocytosis is a neoplastic disease of mast cells harboring the activating KIT mutation D816V. In most patients, mast cell infiltration in the bone marrow is accompanied by marked microenvironment alterations, including increased angiogenesis, osteosclerosis, and sometimes fibrosis. Little is known about the mast cell-derived molecules contributing to these bone marrow alterations. We show here that neoplastic mast cells in patients with systemic mastocytosis express oncostatin M (OSM), a profibrogenic and angiogenic modulator. To study the regulation of OSM expression, KIT D816V was inducibly expressed in Ba/F3 cells and was found to up-regulate OSM mRNA and protein levels, suggesting that OSM is a KIT D816V-dependent mediator. Correspondingly, KIT D816V(+) HMC-1.2 cells expressed significantly higher amounts of OSM than the KIT D816V(-) HMC-1.1 subclone. RNA interference-induced knockdown of STAT5, a key transcription factor in KIT D816V(+) mast cells, inhibited OSM expression in HMC-1 cells, whereas a constitutively activated STAT5 mutant induced OSM expression. Finally, OSM secreted from KIT D816V(+) mast cells stimulated growth of endothelial cells, fibroblasts, and osteoblasts, suggesting that mast cell-derived OSM may serve as a key modulator of the marrow microenvironment and thus contribute to the pathology of systemic mastocytosis.

Helicobacter pylori induces expression and secretion of oncostatin M in macrophages in vitro

BACKGROUND

Helicobacter pylori is pathogenic bacterium that is associated with several gastric diseases in humans. Disease is characterized by severe inflammatory responses is the stomach that are induced by various chemokines and cytokines. Previous reports indicated that some of these responses are mediated through Janus kinase/signal transducer and activator of transcription (JAK/STAT) signaling.

METHODS

We performed JAK/STAT specific microarrays to identify new components of this signaling pathway, which are affected by Helicobacter pylori infection of THP-1 cells.

RESULTS

We found that expression and secretion of oncostatin M and of its receptor were strongly up-regulated by Helicobacter pylori. OSM secretion was independent of CagA, VacA or Type IV secretion system. Helicobacter pylori culture supernatant induced OSM secretion.

CONCLUSION

The induction of the pleiotropic cytokine oncostatin M suggests a possible role in Helicobacter pylori-mediated inflammation and diseases.

Analytic review: Interleukin-6 in surgery, trauma, and critical care: part I: basic science

A variety of cytokines play a role in the response to an inflammatory stimulus. The interleukin-6 (IL-6)-type cytokines are released in response to tissue injury or an inflammatory stimulus. They act locally and systemically to generate a variety of physiologic responses, principal among them is the acute phase response. The IL-6 type cytokines demonstrate pleiotropy and redundancy of actions. This is made possible by the distinctive characteristics of the IL-6 receptor complex, which contains an ubiquitous subunit that is shared by most IL-6-type cytokines, as well as a cytokine-specific subunit.

Early growth response-1 attenuates liver injury and promotes hepatoprotection after carbon tetrachloride exposure in mice

BACKGROUND & AIMS

Inflammatory gene expression plays a pathological role in acute and chronic hepatic inflammation, yet, inflammation also promotes liver repair by inducing protective mechanisms to limit collateral tissue damage by priming hepatocytes for proliferation. Early growth response (Egr)-1, a transcription factor that regulates inflammatory gene expression, plays a pathological role in many animal models of acute and chronic inflammatory disease. Here, we tested the hypothesis that Egr-1 is beneficial after toxic liver injury.

METHODS

Acute liver injury was induced in wild-type and egr-1-/- mice by a single injection of carbon tetrachloride (CCl(4)). Liver injury, inflammatory, and hepatoprotective gene expression and signaling events were measured 18, 48, and 72 h after CCl(4) administration.

RESULTS

Peak liver injury was greater in egr-1-/- mice compared to wild-type mice. Enhanced injury in egr-1-/- mice was associated with reduced tumor necrosis factor (TNF)alpha mRNA and protein expression, reduced Akt phosphorylation and nuclear localization of NFkappaB-p65 in nuclei of cells in the hepatic sinusoid. Expression of inducible nitric oxide synthase and cyclooxygenase-2, TNFalpha-regulated genes that have hepatoprotective function, was attenuated in egr-1-/- mice compared to wild-type mice. Although plasma interleukin (IL)-6 protein and hepatic accumulation of IL-6, glycoprotein 130, and IL-6 receptor alpha mRNA in wild-type and egr-1-/- mice were equivalent, signal transducer and activator of transcription 3 phosphorylation was attenuated in egr-1-/- mice and associated with reduced oncostatin M expression.

CONCLUSIONS

In contrast to its role in inflammation-mediated tissue injury in other models, Egr-1 expression promotes protection in the liver after CCl(4) exposure.

Ovarian cancer-derived lysophosphatidic acid stimulates secretion of VEGF and stromal cell-derived factor-1 alpha from human mesenchymal stem cells

Lysophosphatidic acid (LPA) stimulates growth and invasion of ovarian cancer cells and tumor angiogenesis. Cancer-derived LPA induces differentiation of human adipose tissue-derived mesenchymal stem cells (hASCs) to alpha-smooth muscle actin (alpha-SMA)-positive cancer-associated fibroblasts. Presently, we explored whether cancer-derived LPA regulates secretion of pro-angiogenic factors from hASCs. Conditioned medium (CM) from the OVCAR-3 and SKOV3 ovarian cancer cell lines stimulated secretion angiogenic factors such as stromal-derived factor-1 alpha (SDF-1 alpha) and VEGF from hASCs. Pretreatment with the LPA receptor inhibitor Ki16425 or short hairpin RNA lentiviral silencing of the LPA((1)) receptor abrogated the cancer CM-stimulated expression of alpha-SMA, SDF-1, and VEGF from hASCs. LPA induced expression of myocardin and myocardin-related transcription factor-A, transcription factors involved in smooth muscle differentiation, in hASCs. siRNA-mediated depletion of endogenous myocardin and MRTF-A abrogated the expression of alpha-SMA, but not SDF-1 and VEGF. LPA activated RhoA in hASCs and pretreatment with the Rho kinase inhibitor Y27632 completely abrogated the LPA-induced expression of alpha-SMA, SDF-1, and VEGF in hASCs. Moreover, LPA-induced alpha-SMA expression was abrogated by treatment with the ERK inhibitor U0126 or the phosphoinositide-3-kinase inhibitor LY294002, but not the PLC inhibitor U73122. LPA-induced VEGF secretion was inhibited by LY294002, whereas LPA-induced SDF-1 secretion was markedly attenuated by U0126, U73122, and LY294002. These results suggest that cancer-secreted LPA induces differentiation of hASCs to cancer-associated fibroblasts through multiple signaling pathways involving Rho kinase, ERK, PLC, and phosphoinositide-3-kinase.

Effect of oncostatin M on uridine diphosphate-5'-glucuronosyltransferase 1A1 through cross talk with constitutive androstane receptor

Hyperbilirubinemia remains a common condition in neonates. The constitutive androstane receptor (CAR) is an orphan nuclear receptor that has been shown to participate in the activation of the uridine diphosphate-5'-glucuronosyltransferase 1A1 (UGT1A1) gene, which plays an important role in bilirubin clearance. Oncostatin M (OSM), a member of the IL-6 family, is involved in the maturation of fetal hepatocytes. We have demonstrated that low OSM levels are a potential indicator of neonatal jaundice and the need for phototherapy. In this study we examined the effects of OSM on CAR-mediated signaling to investigate its potential role in neonatal jaundice via the CAR-UGT1A1 pathway. We observed that OSM positively augmented the CAR and UGT1A1 expressions and CAR-mediated signaling in vivo and in vitro, through cross talk between the nuclear CAR receptor and the plasma membrane OSM receptor, via the MAPK cascade. These data suggest that OSM might play a role in bilirubin metabolism via the CAR-UGT1A1 pathway.

The inflammatory mediator oncostatin M induces angiopoietin 2 expression in endothelial cells in vitro and in vivo

OBJECTIVES

Members of the glycoprotein 130 (gp130) receptor-gp130 ligand family play a role in angiogenesis in different tissues. We tested the effect of this cytokine family on the angiopoietin (Ang)-Tie system, which is involved in blood vessel maturation, stabilization, and regression.

RESULTS

Oncostatin M (OSM) increased Ang2 expression in human umbilical vein endothelial cells via Janus kinase/signal transducer and activator of transcription (JAK/STAT) and mitogen-activated protein (MAP) kinase activation. Furthermore, OSM induced Ang2 expression in macrovascular endothelial cells isolated from the human aorta and in microvascular endothelial cells isolated from human heart. Our in vivo experiments revealed that mRNA expression of Ang2 in hearts of mice injected with OSM increased significantly, and levels of OSM mRNA significantly correlated with mRNA levels of Ang2 in human hearts. In addition, OSM increased the expression of its own receptors, gp130 and OSM receptor, in endothelial cells in vitro and in mice in vivo, and levels of OSM mRNA significantly correlated with mRNA levels of gp130 and OSM receptor in human hearts.

CONCLUSION

Our data, showing the effects of OSM on the Ang-Tie system in endothelial cells, in hearts of mice, and in human heart tissue, provide yet another link between inflammation and angiogenesis.

Oncostatin M pathway plays a major role in the renal acute phase response

The acute phase response is traditionally characterized by hepatic synthesis of proteins as an inflammatory response to injury, with interleukin-6 (IL-6) being the key mediator. In contrast, microarray studies in human renal transplant implantation biopsies indicate a strong acute phase response in the deceased donor kidney, associated with a significant upregulation of oncostatin M receptor β (OSMR). The aim of this study was to determine whether the kidney can generate a strong acute phase response, mediated by the OSM/OSMR gateway. Genes associated with the IL-6 cytokine family and acute phase reactants were analyzed by real-time RT-PCR in four groups of human biopsies spanning a spectrum of renal injury. OSM, OSMR, and fibrinogen β (FGB) were progressively more highly expressed from prenephrectomy, living donor, deceased donor, to discarded donor kidneys, suggesting correlation with severity of injury and local renal synthesis. Acute phase response gene expression was analyzed in human proximal tubular cells in culture in response to OSM. OSM induced a significant increase in expression of FGB, OSMR, serpin peptidase inhibitor A1, IL-6, and lipopolysaccharide binding protein, and a decrease in IL-6R. These changes were largely attenuated by coincubation with an OSMR blocking antibody, indicating the OSM effect was mediated through OSMR. OSM also resulted in a significantly altered expression of acute phase genes compared with IL-6 or leukemia inhibitory factor, suggesting that OSM is the predominant cytokine mediating the renal tubular acute phase response. In conclusion, the renal parenchyma is capable of generating a strong acute phase response, likely mediated via OSM/OSMR.

Molecular basis of oncostatin M-induced SOCS-3 expression in astrocytes

Under neuropathological conditions, reactive astrocytes release cytokines and chemokines, which act in an autocrine and/or paracrine fashion to modulate production of immunoregulatory factors from cells including microglia, astrocytes, and neurons. In this way, astrocytes play an important role in orchestrating immune responses within the central nervous system (CNS). Suppressor of cytokine signaling (SOCS) proteins are endogenous, negative regulators of the JAK/STAT signaling pathway and function as attenuators of the immune and inflammatory responses. As such, SOCS proteins may have critical roles in the CNS under neuroinflammatory conditions. In the inflamed CNS, expression of IL-6 cytokine family member oncostatin M (OSM) is elevated; however, its functional effects are not well understood. We demonstrate that OSM is a potent inducer of SOCS-3 in astrocytes. Analysis of the SOCS-3 promoter revealed that an AP-1 element, two IFN-gamma activation sequence (GAS) elements, and a GC-rich region are crucial for SOCS-3 gene expression. Using small interfering RNA against STAT-3, as well as a STAT-3 dominant-negative construct, we demonstrate that STAT-3 activation is critical for OSM induction of SOCS-3 expression. The ERK1/2 and JNK pathways also contribute to OSM-induced SOCS-3 gene expression. OSM stimulation led to a time-dependent recruitment of the transcription factors STAT-3, c-Fos, c-Jun, and Sp1 and the coactivators CREB-binding protein (CBP) and p300 to the endogenous SOCS-3 promoter. These data indicate that OSM-induced activation of STAT-3 and the ERK1/2 and JNK pathways are critical for astrocytic expression of SOCS-3, which provides for feedback inhibition of cytokine-induced inflammatory responses in the CNS.

Formation of large vacuoles induced by cooperative effects of oncostatin M and dexamethasone in human fetal liver cells

The morphology of human fetal liver cells treated with both oncostatin M and dexamethasone was strikingly different from those of cells treated with either oncostatin M or dexamethasone alone. Cotreatment with oncostatin M and dexamethasone resulted in the appearance of numerous large vacuoles. The size of the vacuoles varied among individual cells, ranging from 0.05 to 20 mum depending on the cell. Electron microscopy indicated that swollen large vacuoles in the human fetal liver cells were generally electron lucent. On the other hand, relatively small vacuoles about 2 mum in diameter were discrete structures that contained electron-dense material, such as partially degraded cytoplasmic membrane, cytoplasm, or organelle components. An autophagosome-like organelle was formed in cytoplasm. Electron microscopic analysis indicated direct fusion among the vacuoles formed in the cytoplasm of human fetal liver cells. To our knowledge, this is the first report of large swollen vacuoles formed in cells by the cooperative effects of oncostatin M and dexamethasone.

Oncostatin M promotes osteogenesis and suppresses adipogenic differentiation of human adipose tissue-derived mesenchymal stem cells

Oncostatin M (OSM) is a multifunctional cytokine of the interleukin-6 family and has been implicated in embryonic development, differentiation, inflammation, and regeneration of liver and bone. In the present study, we demonstrated that treatment of human adipose mesenchymal stem cells (hADSCs) with OSM-attenuated adipogenic differentiation, as indicated by decreased accumulation of intracellular lipid droplets and down-regulated expression of adipocytic markers, such as lipoprotein lipase and PPARgamma. However, OSM treatment stimulated osteogenic differentiation, as demonstrated by the increase in matrix mineralization and expression levels of osteogenic differentiation markers, including alkaline phosphatase, Runx2, and osteocalcin. OSM treatment induced activation of JAK2, JAK3, and ERK in hADSCs, and pre-treatment of hADSCs with the JAK2 inhibitor, AG490, significantly restored the OSM-induced inhibition of adipogenic differentiation. Whereas, the JAK3 inhibitor, WHI-P131, and the MEK inhibitor, U0126, had no effects on the anti-adipogenic activity of OSM. On the other hand, the pro-osteogenic activity of OSM was prevented by treatment of the cells with WHI-P131 or U0126, but not with AG490. These results indicate that distinct signaling pathways, including JAK2, JAK3, and MEK-ERK, play specific roles in the OSM-induced anti-adipogenic and pro-osteogenic differentiation of hADSCs.

Oncostatin M-induced effects on EMT in human proximal tubular cells: differential role of ERK signaling

Growing evidence suggests that a proportion of interstitial myofibroblasts detected during renal tubulointerstitial fibrosis originates from tubular epithelial cells by a process called epithelial-mesenchymal transition (EMT). The IL-6-type cytokine oncostatin M (OSM) has been recently implicated in the induction of EMT. We investigated OSM effects on the expression of both cell-cell contact proteins and mesenchymal markers and studied OSM-induced intracellular signaling mechanisms associated with these events in human proximal tubular cells. Human recombinant OSM attenuated the expression of N-cadherin, E-cadherin, and claudin-2 in human kidney-2 (HK-2) cells associated with the induction of HK-2 cell scattering in 3D collagen matrices. Conversely, expression of collagen type I, vimentin, and S100A4 was induced by OSM. OSM-stimulated cell scattering was inhibited by antibodies against gp130. Besides inducing phosphorylation of Stat1 and Stat3, OSM led to a strong concentration- and time-dependent phosphorylation of the mitogen-activated protein kinases ERK1, ERK2, and ERK5. MEK1/2 inhibitor U0126 (10 muM) blocked basal and OSM-induced ERK1/2 phosphorylation but not phosphorylation of either ERK5 or Stat1/3. Both synthetic MEK1/2 inhibitors U0126 and Cl-1040, when used at concentrations which inhibit ERK1/2 phosphorylation but not ERK5 phosphorylation, restored N-cadherin expression in the presence of OSM, inhibited basal claudin-2 expression, but did not affect either basal or OSM-inhibited E-cadherin expression or OSM-induced expression of collagen type I and vimentin. These results suggest that in human proximal tubular cells ERK1/2 signaling represents an important component of OSM's inhibitory effect on N-cadherin expression. Furthermore, functional ERK1/2 signaling is necessary for basal claudin-2 expression.

Oncostatin M gene therapy attenuates liver damage induced by dimethylnitrosamine in rats

To assess the usefulness of oncostatin M (osm) gene therapy in liver regeneration, we examined whether the introduction of OSM cDNA enhances the regeneration of livers damaged by dimethylnitrosamine (DMN) in rats. Repeated injection of OSM cDNA enclosed in hemagglutinating virus of Japan envelope into the spleen resulted in the exclusive expression of OSM protein in Kupffer cells of the liver, which was accompanied by increases in body weight, liver weight, and serum albumin levels and the reduction of serum liver injury parameters (bilirubin, aspartate aminotransferase, and alanine aminotransferase) and a serum fibrosis parameter (hyaluronic acid). Histological examination showed that osm gene therapy reduced centrilobular necrosis and inflammatory cell infiltration and augmented hepatocyte proliferation. The apoptosis of hepatocytes and fibrosis were suppressed by osm gene therapy. Time-course studies on osm gene therapy before or after DMN treatment showed that this therapy was effective not only in enhancing regeneration of hepatocytes damaged by DMN but in preventing hepatic cytotoxicity caused by subsequent treatment with DMN. These results indicate that OSM is a key mediator for proliferation and anti-apoptosis of hepatocytes and suggest that osm gene therapy is useful, as preventive and curative means, for the treatment of patients with liver damage.

Global transcriptional analysis delineates the differential inflammatory response interleukin-15 elicits from cultured human T cells

OBJECTIVE

Interleukin 15 (IL)-15 controls proliferation and survival of T cells, but its effects and the underlying cellular regulation are not well understood. Previous studies have focused on its effects on short-term T-cell cultures. In view of the potential problems associated with using IL-2 alone in adoptive immunotherapy protocols, we investigated the impact of IL-15 on T-cell cultures and the global transcriptional effects it elicits in such cultures.

MATERIALS AND METHODS

DNA microarrays and flow cytometry were used to examine the differential effect of 20 ng/mL IL-15 on primary serum-free T-cell cultures activated and cultured in the presence of IL-2. Quantitative reverse transcriptase polymerase chain reaction confirmed select microarray data.

RESULTS

IL-15 significantly increased ex vivo expansion of primary human T cells over the entire 11-day expansions without affecting viability. The 1133 genes were consistently differentially expressed among three donor samples. Ontological analysis demonstrated that IL-15 increases expression of genes involved in inflammatory response (e.g., tumor necrosis factor [TNF]-alpha, Oncostatin M, CD40L, and CD33) and apoptosis (e.g., TNF-related apoptosis-inducing ligand). IL-15 also induced expression of four suppressors of cytokine signaling (SOCS) family genes (SOCS1-3, cytokine-inducible SH2-containing protein), which are classical negative regulators of cytokine signaling. IL-15 strongly suppressed the expression of inhibitory natural killer cell receptor genes, including three C-type lectins (KLRB1, KLRC1, and KLRD1), as well as IL-7Ra and Granzyme H. Finally, IL-15 induced differential expression of TNF receptor superfamily members (CD27 and CD30).

CONCLUSION

These findings suggest that exogenous IL-15 may have a potential role in adoptive immunotherapy by both enhancing proliferation and modulating functionality during ex vivo T-cell expansion.

Molecular and Functional Characterization of a Soluble Form of Oncostatin M/Interleukin-31 Shared Receptor

Activation of the signaling transduction pathways mediated by oncostatin M (OSM) requires the binding of the cytokine to either type I OSM receptor (leukemia inhibitory factor receptor/gp130) or to type II OSM receptor (OSMR/gp130). In the present work we have developed an enzyme-linked immunosorbent assay detecting a soluble form of OSMR (sOSMR) secreted by glioblastoma, hepatoma, and melanoma tumor cell lines. sOSMR was also present in sera of healthy individuals, with increased levels in multiple myeloma. Molecular cloning of a corresponding cDNA was carried out, and it encoded for a 70-kDa protein consisting of a half cytokine binding domain containing the canonical WSXWS motif, an immunoglobulin-like domain, and the first half of a second cytokine binding domain with cysteines in fixed positions. Analysis of the soluble receptor distribution revealed a preferential expression in lung, liver, pancreas, and placenta. sOSMR was able to bind OSM and interleukin-31 when associated to soluble gp130 or soluble interleukin-31R, respectively, and to neutralize both cytokine properties. We have also shown that OSM could positively regulate the synthesis of its own soluble receptor in tumor cells.

Oncostatin M stimulates expression of stromal-derived factor-1 in human mesenchymal stem cells

Stromal-derived factor-1 (SDF-1) is a CXC chemokine that attracts leukocytes and endothelial progenitor cells. In the present study, we demonstrated that oncostatin M (OSM) stimulates expression and secretion of SDF-1 in both human adipose tissue-derived mesenchymal stem cells (hATSCs) and bone marrow-derived mesenchymal stem cells. The OSM-stimulated expression of SDF-1 in hATSCs was completely abrogated by pretreatment of the cells with U0126, an MEK-specific inhibitor, but not with AG490, a JAK2 inhibitor, or WHI-P131, a JAK3 inhibitor, suggesting that ERK, but not JAK2 and JAK3, is involved in the OSM-induced expression of SDF-1. Pretreatment of hATSCs with anti-VEGF neutralizing antibody or VEGF receptor inhibitors, SU5416 and KRN633, had no significant impact on the OSM induction of SDF-1. Furthermore, treatment of hATSCs with recombinant human VEGF165 or adenoviral overexpression of VEGF did not increase the expression of SDF-1. These results suggest that OSM induces secretion of SDF-1 through ERK-, but not VEGF-, dependent signaling pathways in mesenchymal stem cells.