表皮生长因子干预人羊膜间充质干细胞的增殖和迁移

背景：人羊膜间充质干细胞移植可促进皮肤创伤的愈合。 目的：观察表皮生长因子对体外培养人羊膜间充质干细胞增殖和迁移的影响。 方法：人羊膜间充质干细胞经分离、鉴定并培养至第3代。细胞经过不同浓度的表皮生长因子处理后,用MTT法测量吸光度值从而计算出细胞存活率,通过计数穿过Transwell小室的细胞数测定表皮生长因子对细胞迁移能力的影响;并用表皮生长因子受体的抑制剂AG1478及PI3K的抑制剂LY294002检测其对细胞迁移能力的影响。 结果与结论：表皮生长因子处理后细胞的吸光度值升高1.55倍,穿过膜的数量增高1.5倍;AG1478、LY294002对表皮生长因子引起的迁移有抑制作用。提示表皮生长因子处理后细胞增殖和迁移能力均增强,迁移与EGFR-PI3K信号通路有关。     

Heparin alters epidermal growth factor metabolism in cultured rat glomerular epithelial cells.

Extracellular matrix plays an important role in regulating cell growth. The authors have previously shown that heparin and heparan sulfate inhibit glomerular visceral epithelial cell (GEC) growth and that epidermal growth factor (EGF) can partially reverse the effect of heparin. The authors studied EGF processing by GEC in an attempt to clarify the mechanism by which heparin inhibits GEC growth. Control and heparin-treated GEC rapidly internalized 125I-EGF (within 15 minutes). In heparin-treated cells, 125I-EGF reappeared on the cell surface during the course of a 1-hour incubation and the percent internalized dropped significantly to 59.0% +/- 8.6%, suggesting recycling of 125I-EGF-occupied receptors. After incubation with 125I-EGF, heparin-treated cells also released significantly more cpm of 125I into EGF-free medium (2526 +/- 68 cpm-H; 903 +/- 32-C). Analysis of the released 125I by gel filtration chromatography showed more totally degraded 125I-EGF in media from heparin-treated cells (30.8% +/- 1.6% in heparin-treated versus 17.8% +/- 3.2 in control; P less than 0.05). Analysis of EGF-induced dimerization of receptors showed no effect of heparin on this ratio. These studies suggest that heparin decreases GEC response to EGF by accelerating its uptake and degradation. Matrix alterations in disease states may thus play a role in altering cell responsiveness to growth factors.     

Insulin-like growth factor binding protein-6 inhibits the growth of human bronchial epithelial cells and increases in abundance with all-trans-retinoic acid treatment

Retinoids are potent inhibitors of human bronchial epithelial (HBE) cell growth. Retinoids initiate signaling through activation of nuclear receptors, but the signal transduction pathways that mediate growth inhibition have not been defined. In this study, we investigated the expression of insulin-like growth factor (IGF)-binding protein (IGFBP)-6 as a potential mediator of retinoid actions. IGFBP-6 is a secreted glycoprotein that inhibits the bioavailability of IGFs, which are potent mitogens of HBE cells. IGFBP-6 was detected by immunohistochemical staining in the basal epithelial layer of human bronchial organ cultures, and all-trans-retinoic acid (t-RA) treatment increased the intensity of IGFBP-6 immunostaining. In primary cultures of HBE cells treated with t-RA, IGFBP-6 messenger RNA and protein levels increased within 6 and 24 h, respectively, and IGFBP-6 was detected in the conditioned media at 48 h. The effect of IGFBP-6 on HBE cell growth was investigated with a recombinant adenoviral vector, Ad5CMV-BP6, which expresses IGFBP-6 under the control of a cytomegalovirus promoter. IGFBP-6 overexpression induced a proliferative arrest of HBE cells with no evidence of apoptosis. These findings provide the first evidence that IGFBP-6 is expressed in the bronchial epithelium and that IGFBP-6 may contribute to the biologic effects of retinoids on HBE cells.     

Trefoil factor family 3 peptide promotes human airway epithelial ciliated cell differentiation

Human airway surface epithelium is frequently damaged by inhaled factors (viruses, bacteria, xenobiotic substances) as well as by inflammatory mediators that contribute to the shedding of surface epithelial cells. To regain its protective function, the epithelium must rapidly repair and redifferentiate. The Trefoil Factor Family (TFF) peptides are secretory products of many mucous cells. TFF3, the major TFF in the airways, is able to enhance airway epithelial cell migration, but the role of this protein in differentiation has not been defined. To identify the specific role of TFF3 in the differentiation of the human airway surface epithelium, we analyzed the temporal expression pattern of TFF3, MUC5AC, and MUC5B mucins (goblet cells) and ciliated cell markers beta-tubulin (cilia) and FOXJ1 (ciliogenesis) during human airway epithelial regeneration using in vivo humanized airway xenograft and in vitro air-liquid interface (ALI) culture models. We observed that TFF3, MUC5AC, MUC5B, and ciliated cell markers were expressed in well-differentiated airway epithelium. The addition of exogenous recombinant human TFF3 to epithelial cell cultures before the initiation of differentiation resulted in no change in MUC5AC or cytokeratin 13 (CK13, basal cell marker)-positive cells, but induced an increase in the number of FOXJ1-positive cells and in the number of beta-tubulin-positive ciliated cells (P < 0.05). Furthermore, this effect on ciliated cell differentiation could be reversed by specific epidermal growth factor (EGF) receptor (EGF-R) inhibition. These results indicate that TFF3 is able to induce ciliogenesis and to promote airway epithelial ciliated cell differentiation, in part through an EGF-R-dependent pathway.     

Autocrine ligands for the epidermal growth factor receptor mediate interleukin-8 release from bronchial epithelial cells in response to cigarette smoke

Surfactant replacement preparations containing either surfactant protein (SP)-B or SP-C significantly improve lung function in surfactant-deficient infants, suggesting that these peptides may be functionally redundant. SP-B is absent and SP-C is greatly diminished in the airspaces of SP-B (-/-) mice, which die of respiratory distress syndrome (RDS) shortly after birth. The goal of this study was to determine if elevated expression of SP-C mature peptide could reverse the neonatal lethality in SP-B (-/-) mice. SP-C peptide (residues 24-57 of mouse SP-C proprotein) with a hemagglutinin epitope (SP-C(24-57)HA) was expressed in type II cells of transgenic mice, with the goal of crossing these animals into the SP-B (-/-) background. Unexpectedly, expression of the SP-C(24-57)HA transgene resulted in delayed/arrested lung development and lethal, neonatal RDS of all transgenic progeny in two independent transgenic lines. In transgenic mice, SP-C(24-57)HA was localized predominantly to the endoplasmic reticulum and Golgi; in contrast, SP-B and SP-C were very difficult to detect in the endoplasmic reticulum of wild-type mice. These results suggest that elevated expression of SP-C(24-57)HA in type II cells resulted in aggregation of SP-C in the early secretory pathway, leading to cytotoxicity and, ultimately, altered lung development.     

Transforming growth factor alpha and epidermal growth factor in human pancreatic cancer.

Overexpression of the epidermal growth factor receptor (EGFR) has been reported as an important molecular abnormality in human pancreatic cancer. There is in vitro evidence that simultaneous overproduction of one of its ligands, transforming growth factor alpha (TGF-alpha), might result in an autocrine loop with an increased proliferation signal. We analysed by immunocytochemical staining a retrospective series of human pancreatic cancers, chronic pancreatitis, and normal fetal and adult pancreatic tissues for the presence of TGF-alpha and epidermal growth factor (EGF). Ductal epithelial cells showed TGF-alpha immunoreactivity in both normal tissue and chronic pancreatitis, and 95 per cent of tumours showed strong immunoreactivity. In contrast, EGF immunoreactivity was not found in normal pancreas, but was expressed in 12 per cent of pancreatic carcinomas. Well-defined areas of EGF immunoreactivity in exocrine ducts showing reactive changes in pancreatitis might represent a benign response to tissue damage similar to that previously described in the gastric mucosa.     

TRPC1在TGF-β1诱导支气管上皮细胞迁移中的作用

 目的: 探究经典瞬时受体电位通道1(TRPC1)在转化生长因子β1(TGF-β1)诱导人支气管上皮细胞(16HBE)迁移中的作用。方法: siRNA沉默TRPC1; CCK-8法和流式细胞术分别检测细胞活力和凋亡; 细胞划痕和Transwell小室实验检测细胞的迁移和侵袭。Western blot检测E-钙黏蛋白和vimentin的蛋白表达。结果: TGF-β1刺激细胞后,TGF-β1组细胞的迁移距离大于对照组(P < 0.01)。TGF-β1组和TRPC1沉默组的细胞活力和凋亡与对照组相比差异不显著;与TGF-β1组细胞比较,siRNA和 TGF-β1 共同作用组迁移能力明显降低(P < 0.01)。与 TGF-β1 组相比,siRNA沉默TRPC1和 TGF-β1 共同作用组E-钙黏蛋白的蛋白表达明显降低(P < 0.05),而vimentin的蛋白表达明显增强(P < 0.05)。结论: TRPC1通过调节E-钙黏蛋白和vimentin 的蛋白表达参与了TGF-β1诱导人支气管上皮细胞迁移的过程。     

The effect of epidermal growth factor on vascular endothelial growth factor secretion by endometrial stromal cells

Endometrial stromal cells undergo morphological and functional changes to facilitate oocyte implantation under regulation of various hormones and growth factors. We studied physiological induction by epidermal growth factor (EGF) of vascular endothelial growth factor (VEGF) in these cells. In human endometrial stromal cells, the effect of EGF, genistein, tryphostin AG1478 (a tyrosine kinase inhibitor), and wortmannin (a phosphatidylinositol 3-kinase inhibitor) on production of VEGF was examined: Total RNA was extracted and VEGF mRNA expression was quantified by Northern analysis. EGF induced production of VEGF by stromal cells in a time-dependent manner; the effect became significant after 12 h and increased further between 24 and 48 h (P<0.05). Dose dependency was also significant (P<0.01). Genistein, tryphostin AG1478, and wortmannin partially suppressed the increase in production induced by EGF (P<0.01, P< 0.01, P<0.01), respectively. Production of EGF by fertilized oocytes and trophoblasts has been reported in early pregnancy. VEGF is believed to be induced by EGF through mechanisms involving tyrosine kinase and phosphatidylinositol 3-kinase. The increase in VEGF may contribute to neovascularization that promotes proliferation of endometrium and placentation. Received: 6 September 2001 / Accepted: 21 May 2002     

Macrophages promote epithelial repair through hepatocyte growth factor secretion

Macrophages play a critical role in intestinal wound repair. However, the mechanisms of macrophage‐assisted wound repair remain poorly understood. We aimed to characterize more clearly the repair activities of murine and human macrophages. Murine macrophages were differentiated from bone marrow cells and human macrophages from monocytes isolated from peripheral blood mononuclear cells of healthy donors (HD) or Crohn's disease (CD) patients or isolated from the intestinal mucosa of HD. In‐vitro models were used to study the repair activities of macrophages. We found that murine and human macrophages were both able to promote epithelial repair in vitro. This function was mainly cell contact‐independent and relied upon the production of soluble factors such as the hepatocyte growth factor (HGF). Indeed, HGF‐silenced macrophages were less capable of promoting epithelial repair than control macrophages. Remarkably, macrophages from CD patients produced less HGF than their HD counterparts (HGF level: 84 ± 27 pg/mg of protein and 45 ± 34 pg/mg of protein, respectively, for HD and CD macrophages, P < 0·009) and were deficient in promoting epithelial repair (repairing activity: 90·1 ± 4·6 and 75·8 ± 8·3, respectively, for HD and CD macrophages, P < 0·0005). In conclusion, we provide evidence that macrophages act on wounded epithelial cells to promote epithelial repair through the secretion of HGF. The deficiency of CD macrophages to secrete HGF and to promote epithelial repair might contribute to the impaired intestinal mucosal healing in CD patients.     

Macrophages promote epithelial proliferation following infectious and non-infectious lung injury through a Trefoil factor 2-dependent mechanism

Coordinated efforts between macrophages and epithelia are considered essential for wound healing, but the macrophage-derived molecules responsible for repair are poorly defined. This work demonstrates that lung macrophages rely upon Trefoil factor 2 to promote epithelial proliferation following damage caused by sterile wounding, Nippostrongylus brasiliensis or Bleomycin sulfate. Unexpectedly, the presence of T, B, or ILC populations was not essential for macrophage-driven repair. Instead, conditional deletion of TFF2 in myeloid-restricted CD11c^Cre TFF2 ^flox mice exacerbated lung pathology and reduced the proliferative expansion of CD45⁻ EpCAM⁺ pro-SPC⁺ alveolar type 2 cells. TFF2 deficient macrophages had reduced expression of the Wnt genes Wnt4 and Wnt16 and reconstitution of hookworm-infected CD11c^Cre TFF2^flox mice with rWnt4 and rWnt16 restored the proliferative defect in lung epithelia post-injury. These data reveal a previously unrecognized mechanism wherein lung myeloid phagocytes utilize a TFF2/Wnt axis as a mechanism that drives epithelial proliferation following lung injury.     

Involvement of epidermal growth factor receptor-linked signaling responses in Pseudomonas fluorescens-infected alveolar epithelial cells

Pseudomonas fluorescens is an opportunistic indoor pathogen that can cause severe airway proinflammatory responses. Pulmonary epithelium, like other mucosal epithelial linings of the body, constitutes the first line of defense against airway microbial pathogens. Mucosal epithelial cells can be a sentinel of pathogenic bacteria via stimulation of specific cell surface receptors, including the epidermal growth factor receptor (EGFR) and Toll-like receptor (TLR). This study addressed the involvement of EGFR in airway epithelial pathogenesis by P. fluorescens. Human A549 pneumocytes showed prolonged production of proinflammatory interleukin-8 (IL-8) in response to infection with P. fluorescens, which was via the nuclear factor-kappa B (NF-κB) signaling pathway. Production of proinflammatory cytokine IL-8 was not mediated by P. fluorescens lipopolysaccharide, a representative TLR4 agonist, but was mediated through EGFR-linked signals activated by the opportunistic bacteria. Moreover, EGFR signals were involved in NF-κB signal-mediated production of proinflammatory cytokines. Along with persistent NF-κB activation, P. fluorescens enhanced the EGFR phosphorylation and subsequent activation of downstream mediators, including protein kinase B or extracellular-signal-regulated kinases 1/2. Blocking of EGFR-linked signals increased epithelial susceptibility to pathogen-induced epithelial cell death, suggesting protective roles of EGFR signals. Thus, airway epithelial exposure to P. fluorescens can trigger antiapoptotic responses via EGFR and proinflammatory responses via TLR4-independent NF-κB signaling pathway in human pneumocytes.     

人支气管上皮细胞的体外培养

背景：人支气管上皮细胞培养在呼吸系统疾病研究中应用越来越广泛。 目的：探索美国典型培养物保藏中心人支气管上皮细胞体外培养方法的可行性。 方法：对人支气管上皮细胞培养条件进行反复摸索,最终确定应用含体积分数20%胎牛血清的DMEM/F12培养基进行培养。 结果与结论：实验培养的人支气管上皮细胞扁平,呈多边形,长满后呈“铺路石”样分布,经免疫组化检测发现培养的细胞表达上皮细胞标志物细胞角蛋白。在支气管扩张症患者痰液上清刺激下,细胞表达的核因子κB、肿瘤坏死因子α和白细胞介素8明显增强,证实培养的人支气管上皮细胞获得成功。提示不必拘泥于美国典型培养物保藏中心推荐的培养条件,改进的培养方法简便易行,有应用价值。     

Effect of ozone on platelet-activating factor production in phorbol-differentiated HL60 cells, a human bronchial epithelial cell line (BEAS S6), and primary human bronchial epithelial cells.

Platelet-activating factor (PAF) is a phospholipid with a wide spectrum of pro-inflammatory properties. In the lung, PAF induces airway hyperresponsiveness, neutrophil sequestration, and increased vascular permeability. The alveolar macrophage and the bronchial epithelium are tissues that are exposed to inhaled ozone (O3). We studied the effect of an in vitro O3 exposure on PAF production in a macrophage-like HL60 human cell line (dHL60), a human bronchial epithelial cell line (BEAS S6), and also in primary human bronchial epithelial cells. PAF was quantified by thin-layer chromatographic separation of lipid extracts from cells radiolabeled with [3H]lysoPAF and by radioimmunoassay. In vitro exposure of dHL60 cells to 0.05 to 1.0 ppm O3 for 15 to 120 min was found to significantly increase PAF levels above air control values at all exposure levels and time points (average increase of 92%). Similarly, BEAS S6 cells grown on collagen-coated filter supports and exposed to 0.05 to 1.0 ppm O3 for 60 min released an average increase in PAF of 626% above control values. Primary human bronchial epithelial cells also demonstrated significant increases in [3H]PAF release (average increase of 289% after exposure to 1.0 ppm O3 for 60 min) compared with paired air controls. These findings suggest that some of the effects of O3 inhalation may be mediated by PAF.     

Inhibitory effect of statins on inflammatory cytokine production from human bronchial epithelial cells

Statins are 3-hydroxy-3-methylglutaryl-co-enzyme A reductase inhibitors of cholesterol biosynthesis, and have been reported to exert pleiotropic effects on cellular signalling and cellular functions involved in inflammation. Recent reports have demonstrated that previous statin therapy reduced the risk of pneumonia or increased survival in patients with community-acquired pneumonia. However, the precise mechanisms responsible for these effects are unclear. In the present study, we examined the effects of statins on cytokine production from lipopolysaccharide (LPS)-stimulated human bronchial epithelial cells (BEAS-2B). Interleukin (IL)-6 and IL-8 mRNA expression and protein secretion in LPS-stimulated cells were inhibited significantly by the lipophilic statin pitavastatin and the hydrophilic statin pravastatin. As these inhibitory effects of statin were negated by adding mevalonate, the anti-inflammatory effects of statins appear to be exerted via the mevalonic cascade. In addition, the activation levels of Ras homologue gene family A (RhoA) in BEAS-2B cells cultured with pitavastatin were significantly lower than those without the statin. These results suggest that statins have anti-inflammatory effects by reducing cytokine production through inhibition of the mevalonic cascade followed by RhoA activation in the lung.     

Gene expression and immunolocalization of heparin-binding epidermal growth factor-like growth factor and human epidermal growth factor receptors in human corpus luteum

BACKGROUND: The objective of this study was to elucidate gene expression and immunolocalization of heparin-binding epidermal growth factor-like growth factor (HB-EGF) and human epidermal growth factor receptor (HER) family in the human ovary during luteal growth and regression. METHODS: Ovaries obtained from pre-menopausal women were used for immunohistochemistry and semiquantitative RT-PCR analysis. RESULTS: Immunoreactive HB-EGF was not detected in follicles or oocyte, while HB-EGF became apparent in granulosa luteal cells in the early luteal phase, and most abundant in the mid-luteal phase, but less abundant in the late luteal phase. Immunostaining for HER1 was very weak in granulosa luteal cells in the early and mid-luteal phases, and was not detected in the late luteal phase. Immunoreactive HER4 was abundant in the early luteal phase and became less abundant in the mid-luteal phase, whereas it was negative in the late luteal phase. Semiquantitative RT-PCR analysis revealed that HB-EGF and HER1 mRNA levels were high in the mid-luteal phase, whereas HER4 mRNA expression was high in the early luteal phase. CONCLUSIONS: HB-EGF may play a vital role in regulating luteal growth in a juxtacrine manner and through activating HER4 signalling.     

Insulin-like growth factor 1 and oestradiol promote cell proliferation of MCF-7 breast cancer cells: new insights into their synergistic effects.

In MCF-7 breast cancer cells, the insulin-like growth factor 1 receptor (IGF-1R) and the oestrogen receptor (ER) are coexpressed and the two signalling systems are engaged in a crosstalk that results in synergistic growth. However, coupling between the signalling cascades is poorly understood. Oestradiol enhances IGF-1R signalling by inducing the expression of insulin receptor substrate 1 (IRS-1), a substrate of the IGF-1R. Oestradiol induced expression of IRS-1 results in enhanced tyrosine phosphorylation of IRS-1 after IGF-1 stimulation, followed by enhanced mitogen activated protein kinase, phosphoinositide 3' kinase, and Akt activation. Oestradiol can also potentiate the effect of IGF-1 on the expression of cyclin D1 and cyclin E, and on the phosphorylation of the retinoblastoma protein (RB). These effects are greatly diminished in SX13 cells, which exhibit a 50% reduction in IGF-1R expression but few functional IGF-1Rs at the surface. Oestradiol and IGF-1 regulate the expression of two cyclin dependent kinase inhibitors, p21 and p27, differently. Whereas IGF-1 increases p21 expression and reduces p27 expression, oestradiol has no effect on p21. In summary, in MCF-7 cells, oestrogen potentiates the effect of IGF-1 on IGF-1R signalling and its effects on certain cell cycle components.     

Macrophage migration inhibitory factor and interleukin-8 produced by gastric epithelial cells during Helicobacter pylori exposure induce expression and activation of the epidermal growth factor receptor

While a link between Helicobacter pylori exposure and gastric cancer has been established, the underlying mechanisms remain unclear. H. pylori induces a chronic inflammatory response in infected individuals. A link between chronic inflammation and carcinogenesis has long been suggested but never elucidated. Epidermal growth factor receptor (EGFR) signaling plays an important role in both proinflammatory and procarcinogenic mechanisms and is upregulated on gastric epithelial cells (GECs) during H. pylori exposure. The aim of this study was to examine the effects of two important proinflammatory cytokines released during H. pylori infection, macrophage migration inhibitory factor (MIF) and interleukin-8 (IL-8), on the expression and transactivation of EGFR and on the proliferation of GECs during H. pylori exposure. The expression of EGFR by GECs was increased by exposure to either H. pylori, recombinant MIF, or recombinant IL-8. However, cag pathogenicity island knockout strains of H. pylori had very little effect on expression. MIF and IL-8 also induced phosphorylation of EGFR, signaling events, and proliferation during H. pylori exposure, all of which were decreased when they were neutralized by these cytokines or were blocked from their receptors. The overall role of EGFR in these responses to H. pylori exposure was assessed by knocking down EGFR expression by small interfering RNA.