TrkA对小鼠过敏性气道反应肺组织Akt/PKB的调节作用

目的 探讨神经生长因子(NGF)受体酪氨酸激酶(TrkA)是否调控丝/苏氨酸激酶(Akt/PKB)磷酸化表达来参与小鼠肺组织过敏性免疫炎性变化。方法 制备卵清蛋白(OVA)致敏的BALB/c小鼠过敏性免疫炎症模型,应用HE肺组织病理染色确定模型成功,采用免疫组织化学、免疫荧光和定量RT-PCR等方法,观察给予TrkA抗体后小鼠肺组织磷酸化Akt(p-Akt)表达变化。结果 p-Akt在过敏性免疫炎症模型小鼠肺组织中表达水平高于正常对照组,TrkA阻断后p-Akt在小鼠肺组织中表达水平明显低于过敏性免疫炎症模型小鼠(p<0.05)。结论 TrkA受体参与NGF介导Akt/PKB传导的小鼠肺部过敏性免疫炎症反应。     

神经生长因子对体外培养角膜缘干细胞的作用

目的探讨神经生长因子(NGF)对体外培养角膜缘干细胞(LSCs)的影响及其受体在LSCs上的表达与细胞增殖的关系。方法体外培养LSCs,分对照组和NGF组传代培养,分别选取各组培养1 d、3 d和5 d的细胞,免疫细胞化学检测p63、TrkA、p75表达。结果 NGF组在1 d、3 d、5 d时间点p63表达平均灰度值低于对照组,差异有统计学意义(P0.05)。NGF组各时间点TrkA表达平均灰度值低于对照组,差异有统计学意义(P0.05)。NGF组各时间点p75表达平均灰度值低于对照组,差异有统计学意义(P0.05)。Pearson相关分析TrkA表达平均灰度值与p63表达平均灰度值,差异有统计学意义(P0.05)。结论NGF有维持LSCs的干细胞特性的作用,LSCs可表达NGF受体TrkA和p75,且TrkA的表达与LSCs的增殖有相关性。     

白血病患者NGF和CD271测定的临床意义

目的:观察初治白血病患者神经生长因子(NGF)及其低亲和性受体CD271的表达水平变化及其临床意义.方法:运用酶标记免疫吸附分析(ELISA)测定40例急/慢性白血病患者(病例组)血清NGF水平以及流式细胞术(FCM)测定白血病细胞群CD271阳性表达率,同时选择35例健康体检者为对照组.结果:病例组患者血清NGF水平...     

神经生长因子及其受体在前列腺癌中的表达

目的探讨神经生长因子(nerve growth factor,NGF)及其受体TrkA、p75在前列腺增生和前列腺癌中的表达。方法采用免疫组织化学SABC法检测前列腺良性增生10例、高分化8例、中分化14例和低分化23例石蜡包埋组织中NGF和TrkA、p75的表达。结果NGF和TrkA在前列腺增生、高分化癌、中分化癌、低分化癌中的均有表达;而p75在前列腺增生全部表达、高分化癌(8/4)、中分化癌(14/6)、低分化癌(23/3)中的表达呈逐渐降低趋势,其差异有显著性(p<0.05),前列腺增生与高分化癌、中分化癌、低分化癌相比差异均有显著性(p<0.05)。结论NGF和TrkA的表达与前列腺增生和前列腺癌进展无关。p75与前列腺癌恶性进展有关,p75表达减少在前列腺癌过程中起着重要的作用。     

哮喘时豚鼠下呼吸道及内脏感觉传入部位Trk A的表达以及神经生长因子对其影响

目的：探讨神经生长因子(NGF)在哮喘发病中的作用及其神经免疫调节机制。方法：应用免疫组织化学方法检测豚鼠下呼吸道和内脏感觉传入部位 NGF 高亲和力受体酪氨酸激酶 A(TrkA),用 Western blot 蛋白印迹方法检测豚鼠肺、脊神经节和脊髓背角 NGF 和 TrkA 的表达。结果：(1)与对照组相比,哮喘豚鼠气道上皮、肺内炎性细胞、血管平滑肌内的神经末梢、C_7～T_5段脊神经节及相应节段脊髓背角内 TrkA 阳性反应产物的平均灰度值均明显降低;哮喘 NGF 抗体组则明显高于哮喘组。(2)哮喘组豚鼠肺、C_7～T_5段脊神经节及相应节段脊髓样品中 TrkA 或 NGF 目标带的 IDV 与内参照 IDV 的比值均明显升高,而哮喘 NGF 抗体组则明显低于哮喘组。结论：NGF 可上调 TrkA 的表达,TrkA 介导的细胞内信号传导系统可能是 NGF 参与哮喘发病的主要途径之一。     

龟板促进帕金森病大鼠黑质神经生长因子信号分子的表达

目的:进一步探讨神经生长因子(NGF)/酪氨酸受体激酶A(TrkA)通路是否为龟板抗帕金森病(PD)大鼠多巴胺能神经元凋亡中的机制.方法:采用大鼠左侧黑质致密带注射6-羟基多巴胺(6-OHDA,0 2%)2μl造成PD模型,同时设立龟板组、模型组和正常对照组,用免疫组织化学显色方法观察PD大鼠中脑黑质NGF、 TrkA和磷酸化的糖原合成酶激酶-3β(p-GSK-3β)阳性神经元数目.免疫印迹法检测NGF、 TrkA、 p-GSK-3β蛋白表达水平的变化.结果:免疫组织化学显色显示龟板组PD大鼠中脑黑质致密部NGF、 TrkA的阳性细胞数明显多于模型组.免疫印迹法结果显示龟板组PD大鼠中脑黑质致密部NGF、 TrkA的蛋白表达水平高于模型组.结论:龟板能上调6-OHDA诱导的PD大鼠中脑黑质NGF、 TrkA和p-GSK-3β的表达,这可能是其抗PD大鼠多巴胺能神经元凋亡的分子机制.     

甲状腺激素通过NGF及TrKA调节中枢胆碱能神经元发育

目的探索甲状腺激素通过神经生长因子(NGF)及其受体TrKA对大鼠顶叶皮层、海马部位中枢胆碱能神经元发育的作用。方法将Wistar大鼠分为3组:①甲状腺功能减退(甲减)组:从母鼠妊娠5～6d起饲以含0.02%的他巴唑饮用水;②甲状腺功能亢进(甲亢)组:仔鼠出生即日起,按体质量腹腔注射T4(0.4μg/g);③对照组:饲以普通饲料及饮用水。于出生后第14、21、28天,免疫组化法检测大鼠顶叶皮层、海马中胆碱乙酰转移酶(ChAT)阳性细胞,原位杂交法测定NGF、TrkA mRNA的表达。结果①出生后第21、28天顶叶皮层、海马中,甲减组(159.42±5.26、162.37±4.67,98.60±7.67、101.50±4.39)ChAT阳性细胞数较对照组(174.80±5.10、171.40±3.87,213.40±16.93、274.60±6.69)明显减少(P<0.05或<0.01),甲亢组(312.50±3.75、296.30±6.13,324.60±15.72、319.10±8.85)ChAT阳性细胞数较对照组明显增加(P<0.01);②对照组顶叶皮层、海马中,ChAT阳性细胞数、NGF、TrkA mR...     

NGF对乳腺癌细胞系MDA-MB-231和MCF-7增殖和存活的影响

目的:研究神经生长因子(NGF)对乳腺癌细胞系MDA-MB-231和MCF-7细胞增殖与存活的影响。方法:运用免疫荧光方法检测NGF及其受体酪氨酸蛋白激酶A(TrkA)的表达;运用酶联免疫吸附测定(ELISA)方法检测细胞的NGF自分泌情况;运用蛋白质印迹(Western blotting)方法检测TrkA蛋白的表达情况;运用NGF阻断剂Ro 08-2750对细胞进行NGF剥夺,通过单核细胞直接细胞毒性测定法(MTT)检测细胞增殖的情况;运用流式细胞仪检测细胞凋亡情况以及细胞周期分布的变化。结果:2株乳腺癌细胞系均表达NGF及其受体TrkA,NGF阻断剂Ro 08-2750能够明显抑制2种细胞的增殖,并具有剂量依赖性;流式细胞仪显示Ro 08-2750处理的MDA-MB-231细胞和MCF-7细胞的S期细胞比例明显增加,G2/M期细胞比例明显降低,MDA-MB-231细胞出现凋亡峰。结论:NGF剥夺明显抑制乳腺癌细胞系MDA-MB-231和MCF-7的增殖,并引起MDA-MB-231细胞凋亡。     

NGF促进神经细胞生长发育的信号通路及与哮喘发病的关系

神经生长因子(NGF)作为第一个被发现的神经营养因子,具有促进神经细胞存活和生长发育的作用。NGF结合酪氨酸受体TrkA,引起胞内四条信号通路:Ras/Raf/Erk蛋白激酶通路,磷脂酰肌醇-3激酶(PI3-K)/Akt激酶通路,磷脂酶c(PLC-γ)通路以及SNT。NGF的另一个受体P75神经营养因子受体(P75NTR)的信号通路仍不是十分清楚,但可与TrkA协同作用,也可单独作用促进神经细胞的存活或凋亡。另外,NGF介导下TrkA的信号通路与哮喘的发病之间有着密切的联系。本文主要就NGF与TrkA和P75NTR蛋白结合后,胞内传导系统及尚待研究解决的问题进行综述。     

神经生长因子在糖尿病足创面组织中表达相关性的研究进展

动物实验研究证实神经生长因子（NGF）促进创面组织血管生成、血管内皮细胞再生,促进缺血创面的愈合及糖尿病创面的愈合。通过NGF在糖尿病创面表达改变的研究,有助于NGF促进糖尿病创面愈合机制的探讨,为糖尿病足创面愈合提供新的理论依据。     

Expression of nerve growth factor in human pancreatic beta cells

Nerve growth factor (NGF) is an important modulator of rat pancreatic beta-cell physiology in vitro. In this study, we analysed the expression of NGF, TrkA and insulin in human pancreatic islets from normal, ductal adenocarcinoma and insulinoma-afflicted samples, using double immunofluorescent labelling and confocal microscopy. We found that in normal human pancreas, insulin and NGF are co-expressed in beta cells. Moreover, similar to previous observations in rat, the high affinity NGF receptor TrkA is also expressed in beta cells. Pancreatic beta cells in normal islets from adenocarcinoma and mucinous cystadenocarcinoma patients also expressed NGF. In 2 out of 15 exocrine tumour samples, NGF was detected also in the tissue surrounding the islets, while 2 out of 13 adenocarcinoma tumours expressed this growth factor. In five insulinoma samples, we observed weaker immunofluorescent labelling of insulin and NGF in the neoplastic tissue, compared to the islets not afflicted by the tumour, which may be a consequence of increased hormone secretion rate. We demonstrate that human beta cells express TrkA and NGF. These findings are consistent with the hypothesis that NGF modulates insulin secretion through a paracrine/autocrine loop, similar to the one observed in cultured rat beta cells.     

Expression of Nerve Growth Factor in Human Pancreatic β Cells

Nerve growth factor (NGF) is an important modulator of rat pancreatic β-cell physiology in vitro. In this study, we analysed the expression of NGF, TrkA and insulin in human pancreatic islets from normal, ductal adenocarcinoma and insulinoma-afflicted samples, using double immunofluorescent labelling and confocal microscopy.

We found that in normal human pancreas, insulin and NGF are co-expressed in β cells. Moreover, similar to previous observations in rat, the high affinity NGF receptor TrkA is also expressed in β cells.

Pancreatic β cells in normal islets from adenocarcinoma and mucinous cystadenocarcinoma patients also expressed NGF. In 2 out of 15 exocrine tumour samples, NGF was detected also in the tissue surrounding the islets, while 2 out of 13 adenocarcinoma tumours expressed this growth factor.

In five insulinoma samples, we observed weaker immunofluorescent labelling of insulin and NGF in the neoplastic tissue, compared to the islets not afflicted by the tumour, which may be a consequence of increased hormone secretion rate.

We demonstrate that human β cells express TrkA and NGF. These findings are consistent with the hypothesis that NGF modulates insulin secretion through a paracrine/autocrine loop, similar to the one observed in cultured rat β cells.     

p75 Neurotrophin Receptor-Mediated Signaling Promotes Human Hair Follicle Regression (Catagen)

Nerve growth factor (NGF) and its apoptosis-promoting low-affinity receptor (p75NTR) regulate murine hair cycling. However, it is unknown whether human hair growth is also controlled through p75NTR, its high-affinity ligand pro-NGF, and/or the growth-promoting high-affinity NGF receptor tyrosine kinase A (TrkA). In microdissected human scalp anagen hair bulbs, mRNA for NGF, pro-NGF, p75NTR, and TrkA was transcribed. Immunohistomorphometry and in situ hybridization detected strong NGF and pro-NGF expression in terminally differentiating inner root sheath keratinocytes, whereas TrkA was co-expressed with p75NTR in basal and suprabasal outer root sheath keratinocytes. During spontaneous catagen development of organ-cultured human anagen hair follicles, p75NTR mRNA levels rose, and p75NTR and pro-NGF immunoreactivity increased dramatically in involuting compartments primarily devoid of TrkA expression. Here, TUNEL(+) apoptotic cells showed prominent p75NTR expression. Joint pro-NGF/NGF administration inhibited hair shaft elongation and accelerated catagen development in culture, which was antagonized by co-administration of p75NTR-blocking antibodies. In addition, mRNA and protein expression of transforming growth factor-beta2 increased early during spontaneous catagen development, and its neutralization blocked pro-NGF/NGF-dependent hair growth inhibition. Our findings suggest that pro-NGF/NGF interacts with transforming growth factor-beta2 and p75NTR to terminate anagen in human hair follicles, implying that p75NTR blockade may alleviate hair growth disorders characterized by excessive catagen development.     

Correlation between NGF/TrkA and microvascular density in human pterygium

Pterygium is a surface ocular lesion that is associated with chronic UV exposure. The primary effect is a solar actinic elastosis within the stroma. All the other changes are secondary. Pterygium is characterized by proliferation, inflammatory infiltrates, fibrosis, angiogenesis and extracellular matrix breakdown. The aim of this study was to correlate microvascular density and nerve growth factor (NGF)/NGF‐receptor transmembrane tyrosine kinase (TrkA) expression in endothelial cells in human pterygium. Specimens of human pterygium obtained from 30 patients who had undergone surgical excision and of 10 normal bulbar conjunctiva were investigated immunohistochemically by using anti‐CD31, anti‐NGF and anti‐TrkA antibodies. Results showed that endothelial cells in human pterygium are immunoreactive to both NGF and its receptor TrkA, and that this immunoreactivity is correlated to microvascular density. The results of this study suggest that an autocrine loop between NGF and its receptor TrkA is activated in pterygium and that it is involved in the angiogenic response taking place in this pathological condition. These data are in accord with recent evidences, which have clearly established that NGF plays a role as an angiogenic factor in several pathological conditions. Understanding the mechanism of angiogenesis in pterygium provides a basis for a rational approach to the development of anti‐angiogenic therapy in patients affected by this disease.     

Structural and Ultrastructural Localization of NGF and NGF Receptors in the Thymus of Subjects Affected by Myasthenia Gravis

We have previously reported that the thymus of patients affected by myasthenia gravis (MG) is characterized by an elevated level of nerve growth factor (NGF), an endogenous polypeptide which plays a marked role in the cell biology of nervous and immune system. A consistent number of studies has shown altered expression of NGF in diseases associated with inflammatory and/or autoimmune responses. To evaluate the biochemical and molecular mechanisms implicated in NGF action in human myasthenic thymus, it is important to identify the cellular and structural organization of NGF receptors. To address this question, we investigated, both at light and electron microscopic levels, the cellular distribution of immunoreactivity for NGF and its low-affinity receptors, (p75) and its high-affinity receptor (TrkA) in the thymus of patients with MG. The present investigation shows that NGF and NGF receptors are overexpressed in the thymic cells of patients with MG compared to control subjects.     

Structural and ultrastructural localization of NGF and NGF receptors in the thymus of subjects affected by myasthenia gravis

We have previously reported that the thymus of patients affected by myasthenia gravis (MG) is characterized by an elevated level of nerve growth factor (NGF), an endogenous polypeptide which plays a marked role in the cell biology of nervous and immune system. A consistent number of studies has shown altered expression of NGF in diseases associated with inflammatory and/or autoimmune responses. To evaluate the biochemical and molecular mechanisms implicated in NGF action in human myasthenic thymus, it is important to identify the cellular and structural organization of NGF receptors. To address this question, we investigated, both at light and electron microscopic levels, the cellular distribution of immunoreactivity for NGF and its low-affinity receptors, (p75) and its high-affinity receptor (TrkA) in the thymus of patients with MG. The present investigation shows that NGF and NGF receptors are overexpressed in the thymic cells of patients with MG compared to control subjects.     

Ligand activation of nerve growth factor receptor TrkA protects monocytes from apoptosis

Nerve growth factor (NGF) receptors are expressed in different cell types outside the nervous system, and increasing evidence indicates that NGF can act as a regulatory molecule during inflammatory and immune responses. In this study, we show that triggering of the high-affinity NGF receptor TrkA with agonists protects monocytes from apoptosis induced by gliotoxin or UVB radiation. TrkA stimulation up-regulates the expression of the anti-apoptotic Bcl-2 family members, Bcl-2, Bcl-XL, and Bfl-1. On the other hand, TrkA stimulation does not change the expression of MHC, CD80, CD86, CD40, and CD54 molecules, nor the antigen-presenting function of monocytes. In addition, during in vitro monocyte to dendritic cell differentiation TrkA expression is progressively lost, suggesting that NGF selectively affects monocyte but not dendritic cell survival.