Interleukin 31 mediates MAP kinase and STAT1/3 activation in intestinal epithelial cells and its expression is upregulated in inflammatory bowel disease

BACKGROUND/AIM: Interleukin 31 (IL31), primarily expressed in activated lymphocytes, signals through a heterodimeric receptor complex consisting of the IL31 receptor alpha (IL31Ralpha) and the oncostatin M receptor (OSMR). The aim of this study was to analyse IL31 receptor expression, signal transduction, and specific biological functions of this cytokine system in intestinal inflammation. METHODS: Expression studies were performed by RT-PCR, quantitative PCR, western blotting, and immunohistochemistry. Signal transduction was analysed by western blotting. Cell proliferation was measured by MTS assays, cell migration by restitution assays. RESULTS: Colorectal cancer derived intestinal epithelial cell (IEC) lines express both IL31 receptor subunits, while their expression in unstimulated primary murine IEC was low. LPS and the proinflammatory cytokines TNF-alpha, IL1beta, IFN-gamma, and sodium butyrate stimulation increased IL31, IL31Ralpha, and OSMR mRNA expression, while IL31 itself enhanced IL8 expression in IEC. IL31 mediates ERK-1/2, Akt, STAT1, and STAT3 activation in IEC resulting in enhanced IEC migration. However, at low cell density, IL31 had significant antiproliferative capacities (p<0.005). IL31 mRNA expression was not increased in the TNFDeltaARE mouse model of ileitis but in inflamed colonic lesions compared to non-inflamed tissue in patients with Crohn's disease (CD; average 2.4-fold increase) and in patients with ulcerative colitis (UC; average 2.6-fold increase) and correlated with the IL-8 expression in these lesions (r = 0.564 for CD; r = 0.650 for UC; total number of biopsies analysed: n = 88). CONCLUSION: IEC express the functional IL31 receptor complex. IL31 modulates cell proliferation and migration suggesting a role in the regulation of intestinal barrier function particularly in intestinal inflammation.     

Molecular regulation of hepatic expression of iron regulatory hormone hepcidin

Iron is a micronutrient that is an essential component that drives many metabolic reactions. Too little iron leads to anemia and too much iron increases the oxidative stress of body tissues leading to inflammation, cell death, and system organ dysfunction, including cancer. Maintaining normal iron balance is achieved by rigorous control of the amount absorbed by the intestine, that released from macrophages following erythrophagocytosis of effete red cells and by either release or uptake from hepatocytes. Hepcidin is a recently characterized molecule that appears to play a key role in the regulation of iron efflux from enterocytes, macrophages, and hepatocytes. It is produced by hepatocytes under basal conditions, in response to alterations in increased iron stores or reduced requirement for erythropoiesis and by inflammation. The proteins that regulate hepcidin expression are presently being defined, albeit that our present understanding is still far from complete. This review focuses on the molecules which regulate hepcidin expression. The subsequent characterization of these proteins using molecular, cellular, and physiological approaches also is discussed along with inflammatory signals and receptors involved in hepcidin expression.     

Iron stores modulate hepatic hepcidin expression by an HFE-independent pathway

BACKGROUND/AIMS: In HFE-related hereditary hemochromatosis an inappropriately low hepatic expression of the iron-regulatory peptide hepcidin (encoded by HAMP) has been suggested to cause iron overload. The aim of the present study was to evaluate whether the hepatic expression of HAMP in relation to iron stores requires HFE or might involve other important iron-related genes including HJV (encoding hemojuvelin) and TFR2 (encoding transferrin receptor-2). METHODS: Using quantitative RT-PCR, the iron-dependent hepatic expression patterns of HAMP, HJV, and TFR2 were evaluated in human and murine HFE-related hemochromatosis. RESULTS: The overall level of hepatic HAMP expression in human and murine HFE-related hemochromatosis is impaired but can still be modulated by iron stores. Moreover, we demonstrate an HFE-independent correlation between the expression of HAMP and TFR2 in mouse and human livers. On the other hand, a strong correlation between the hepatic expression of HAMP and HJV was only found in hemochromatosis patients and Hfe-deficient mice. CONCLUSION: The central pathogenetic step in HFE-related hemochromatosis is an impaired basal expression of HAMP rather than a lack of HAMP upregulation in response to iron stores. An HFE-independent pathway that seems to involve TFR2 and HJV can regulate HAMP expression under conditions of iron overload.     

Anemia in beta-thalassemia patients targets hepatic hepcidin transcript levels independently of iron metabolism genes controlling hepcidin expression

Thalassemia associates anemia and iron overload, two opposite stimuli regulating hepcidin gene expression. We characterized hepatic hepcidin expression in 10 thalassemia major and 13 thalassemia intermedia patients. Hepcidin mRNA levels were decreased in the thalassemia intermedia group which presented both lower hemoglobin and higher plasma soluble transferrin receptor levels. There was no relationship between hepcidin mRNA levels and those of genes controlling iron metabolism, including HFE, hemojuvelin, transferrin receptor-2 and ferroportin. These results underline the role of erythropoietic activity on hepcidin decrease in thalassemic patients and suggest that mRNA modulations of other studied genes do not have a significant impact.     

Expression of Jak3, STAT1, STAT4, and STAT6 in inflammatory arthritis: unique Jak3 and STAT4 expression in dendritic cells in seropositive rheumatoid arthritis

BACKGROUND: Modulation of Jak-STAT signalling may provide an effective therapeutic strategy in inflammatory arthritis. OBJECTIVE: To document Jak-STAT expression in a cohort of patients with active rheumatoid arthritis (RA), spondyloarthritis (SpA), and osteoarthritis (OA) and compare these subsets with normal synovial tissue. METHODS: Synovial tissue biopsy specimens from patients with RA, OA, and SpA and histologically normal tissue (n = 10 in each arthritis group) were examined for the presence of Jak3, STAT1, STAT4, and STAT6 expression using immunohistochemistry. Phenotyping was performed using immunohistochemistry and immunofluorescence. Clinical and serological characteristics of patients with RA expressing Jak3-STAT4 were assessed. RESULTS: STAT1, STAT4, and Jak3 protein expression was generally increased in inflammatory arthritis. In contrast, STAT6 expression was relatively heterogeneous. A subpopulation of CD1a positive dendritic cells unique to seropositive patients with RA was detected. These cells showed intense protein expression for Jak3, STAT4, and STAT6. CONCLUSION: CD1a positive dendritic cells intensely express Jak3, STAT4, and STAT6 in seropositive RA tissue and may be an alternative marker for dendritic cells in their early stages of activation as well as providing a tool for identifying RA at the level of the synovium. Jak3 inhibition may be a potential therapeutic target to prevent dendritic cell maturation in RA. STAT1 expression is increased in inflammatory arthritis, suggesting that its pro-apoptotic and anti-inflammatory effects cannot effectively counteract inflammation. STAT6 expression is heterogeneous in synovium, suggesting a possible homoeostatic role in addition to any anti-inflammatory effects.     

STAT5b mediates the GH-induced expression of SOCS-2 and SOCS-3 mRNA in the liver

Suppressor of cytokine signalling (SOCS) proteins act as part of a classical negative feedback loop regulating cytokine signal transduction. Expression of SOCS proteins is induced in response to cytokines and down-regulates the cytokine signal by inhibiting the JAK/STAT pathway. Growth hormone (GH) was previously shown to induce strong transient expression of SOCS-3 and to a lesser extent CIS, SOCS-1 and SOCS-2 in mouse liver (Adams, T.E., Hansen, J.A., Starr, R., Nicola, N.A., Hilton, D.J., Billestrup, N., 1998. Growth hormone preferentially induces the rapid, transient expression of SOCS-3, a novel inhibitor of cytokine receptor signalling. J. Biol. Chem. 273, 1285-1287.). In this work we have compared GH-induced SOCS gene expression in wild-type and STAT5b-deficient mice, and show that STAT5b is required for the induction of SOCS-2 and SOCS-3 in liver. In contrast, the absence of STAT5b has no effect on the GH-induced expression of CIS and SOCS-2 mRNA in the mammary gland. Suprisingly, there is no activation of SOCS-3 expression in mammary glands of wild-type and STAT5b mutant mice following GH administration. These results highlight both tissue- and factor-specific differences in the regulation of SOCS gene expression by STAT5a/b.     

STAT3蛋白在肝癌组织中的表达及临床意义

目的探讨STAT3和p-STAT3蛋白在肝癌组织中的表达及其临床意义。方法采用免疫组织化学的方法检测了90例肝癌组织及其相应的癌旁组织中STAT3和p-STAT3蛋白的表达,分析STAT3和p-STAT3蛋白表达与临床病理特征及患者预后的关系。特征参数之间用χ2检验;采用Kaplan-Meier法进行生存分析,用Log-rank检验进行曲线间比较;运用Cox回归进行单因素及多因素生存分析。结果肝癌组织中STAT3主要在细胞质中表达,而p-STAT3主要表达在细胞核内;STAT3和p-STAT3在肝癌组织中阳性表达率明显高于癌旁组织;STAT3和p-STAT3蛋白的表达与卫星灶（P=0.033,P〈0.01）、血管浸润（P=0.046,P〈0.01）及AJCC分期（P〈0.01,P〈0.01）有关,与患者的性别（P=0.280,P=0.403）、年龄（P=0.432,P=0.844）、肿瘤大小（P=0.762,P=0.161）、肿瘤数量（P=0.301,P=0.326）、肿瘤的分化程度（P=0.753,P=0.910）及甲胎蛋白（P=0.441,P=0.080）比较差异无统计学意义;肝癌组织中STAT3和p-STAT3蛋白高表达的患者5年生存率明显低于低表达患者。结论 STAT3和p-STAT3蛋白可能参与了肝癌的浸润转移,有望成为一种新的肝癌预后参考指标。     

STAT3在肝衰竭组织中的表达及其与肝前体细胞增殖的关系

目的:探讨p-STAT3在肝衰竭组织中的表达及其与肝前体细胞(HPC)增殖的关系.方法:对76例肝衰竭组织及急慢性轻型肝炎组织进行HE染色以观察病变特点;应用免疫组织化学的方法对肝衰竭组织及急慢性轻型肝炎组织进行OV6,CK19及p-STAT3检测.结果:CK19免疫组化结果表明,亚急性肝衰竭(SALF)组织及慢加急性(亚急性)肝衰竭(ACLF)组织中可见大量增生的胆管,包括典型增生胆管和非典型增生胆管.肝衰竭组织的CK19阳性率(62.5%)明显高于急慢性轻型肝炎的阳性率(30%)(P＜0.05).肝衰竭组织的OV6阳性率(85.7%)明显高于急慢性轻型肝炎的阳性率(35.0%)(P＜0.05).p-STAT3的阳性表达主要位于汇管区增生的胆管细胞、肝前体细胞、炎性细胞、窦内皮细胞及肝细胞的胞核.肝衰竭组织的p-STAT3阳性率(67.9%)明显高于急慢性轻型肝炎的阳性率(25%)(P＜0.05).相关分析表明,OV6的表达与CK19及p-STAT3表达成正相关(rs=0.689,rs=0.239,P＜0.05).结论:肝衰竭组织中存在HPC的增殖;肝衰竭组织中p-STAT3的表达增加,与HPC表达成正相关,提示p-STAT3参与肝衰竭组织中HPC的增殖调控.     

Pretreatment with CO-releasing molecules suppresses hepcidin expression during inflammation and endoplasmic reticulum stress through inhibition of the STAT3 and CREBH pathways

The circulating peptide hormone hepcidin maintains systemic iron homeostasis. Hepcidin production increases during inflammation and as a result of endoplasmic reticulum (ER) stress. Elevated hepcidin levels decrease dietary iron absorption and promote iron sequestration in reticuloendothelial macrophages. Furthermore, increased plasma hepcidin levels cause hypoferremia and the anemia associated with chronic diseases. The signal transduction pathways that regulate hepcidin during inflammation and ER stress include the IL-6-dependent STAT-3 pathway and the unfolded protein response-associated cyclic AMP response element-binding protein-H (CREBH) pathway, respectively. We show that carbon monoxide (CO) suppresses hepcidin expression elicited by IL-6- and ER-stress agents by inhibiting STAT-3 phosphorylation and CREBH maturation, respectively. The inhibitory effect of CO on IL-6-inducible hepcidin expression is dependent on the suppressor of cytokine signaling-3 (SOCS-3) protein. Induction of ER stress in mice resulted in increased hepatic and serum hepcidin. CO administration inhibited ER-stress-induced hepcidin expression in vivo. Furthermore, ER stress caused iron accumulation in splenic macrophages, which could be prevented by CO. Our findings suggest novel anti-inflammatory therapeutic applications for CO, as well as therapeutic targets for the amelioration of anemia in the hypoferremic condition associated with chronic inflammatory and metabolic diseases.     

STAT3 mediates bone marrow mesenchymal stem cell VEGF production

The mechanisms by which mesenchymal stem cells (MSCs) may protect native tissue are incompletely understood. Understanding the mechanisms by which these cells release factors such as vascular endothelial growth factor (VEGF), may lead to enhanced protection. We hypothesized that stress, in the form of hypoxia or TNF, activates MSCs to release VEGF by STAT3 and p38 MAPK dependent mechanisms. Mouse MSCs from wild type (WT) and STAT3 knockout mice (STAT3KO) were harvested and purified by a single-step method using adhesion. The release of VEGF was analyzed by using MSC conditioned media under hypoxia or TNF stimulation with or without p38 MAPK inhibition. Activation of STAT3 and p38 MAPK was determined by analysis of cell lysates. MSCs released VEGF under normoxia, which was associated with constitutive STAT3 activity. STAT3 deficiency resulted in decreased MSC production of VEGF. In response to hypoxia or TNF, MSCs produced more VEGF, which was correlated with hypoxia or TNF activated p38 MAPK and STAT3. The p38 MAPK inhibitor significantly decreased hypoxia-induced or TNF-stimulated VEGF production in WT. Additionally, STAT3 ablation neutralized hypoxia-induced MSC release of VEGF. No effect of p38 MAPK inhibitor alone was observed on MSC release of VEGF in WT. However, inhibition of p38 MAPK blocked release of VEGF in STAT3KO MSCs. MSCs are a potent source of VEGF, the production of which is mediated by STAT3 under normoxia partly; however, following hypoxia or TNF exposure, MSC release of VEGF is mediated by both STAT3 and p38 MAPK.     

丙型肝炎病毒非结构蛋白质5A抑制Hepcidin基因表达并促进肝细胞内铁储留

目的 探讨丙型肝炎病毒(HCV)非结构蛋白质5A (NS5A)对Hepcidin基因表达的影响. 方法 用含HCV NS5A基因的表达质粒pcNS5A瞬时转染QSG7701细胞,采用逆转录-聚合酶链反应及Western blot试验观察HCV NS5A和Hepcidin的mRNA转录水平及蛋白质表达水平,铁染色后观察细胞内铁储留情况.检测数据的多组间比较行单因素方差分析,两两比较行LSD-t检验.结果 转染pcNS5A质粒细胞内有HCV NS5A的mRNA和蛋白的表达,未转染质粒组和转染空白质粒pRc/CMV组细胞内无HCV NS5A的mRNA和蛋白的表达.未转染质粒组、转染pRc/CMV质粒组和转染pcNS5A质粒组细胞的Hepcidin mRNA相对表达量分别为0.711±0.049、0.718±0.052和0.264±0.030,转染pcNS5A组Hepcidin mRNA表达低于未转染质粒组和转染pRc/CMV质粒组(t值分别为- 13.523和- 13.045,P值均＜0.01).转染pcNS5A质粒组细胞Hepcidin蛋白表达较未转染质粒组及转染pRc/CMV质粒组下降,且随着转染pcNS5A质粒剂量的增加,Hepcidin蛋白表达下降更明显.铁染色结果显示,转染pcNS5A质粒细胞内铁较转染pRC/CMV质粒细胞和未转染质粒细胞高.结论 HCV NS5A蛋白能抑制Hepidin的mRNA和蛋白质表达,并引起细胞内铁的储留增加.