Astrocytes in the damaged brain: Molecular and cellular insights into their reactive response and healing potential

Long considered merely a trophic and mechanical support to neurons, astrocytes have progressively taken the center stage as their ability to react to acute and chronic neurodegenerative situations became increasingly clear. Reactive astrogliosis starts when trigger molecules produced at the injury site drive astrocytes to leave their quiescent state and become activated. Distinctive morphological and biochemical features characterize this process (cell hypertrophy, upregulation of intermediate filaments, and increased cell proliferation). Moreover, reactive astrocytes migrate towards the injured area to constitute the glial scar, and release factors mediating the tissue inflammatory response and remodeling after lesion. A novel view of astrogliosis derives from the finding that subsets of reactive astrocytes can recapitulate stem cell/progenitor features after damage, fostering the concept of astroglia as a promising target for reparative therapies. But which biochemical/signaling pathways modulate astrogliosis with respect to both the time after injury and the type of damage? Are reactive astrocytes overall beneficial or detrimental for neuroprotection and tissue regeneration? This debate has been animating this research field for several years now, and an integrated view on the results obtained and the possible future perspectives is needed. With this Commentary article we have attempted to answer the above-mentioned questions by reviewing the current knowledge on the molecular mechanisms controlling and sustaining the reaction of astroglia to injury and its stem cell-like properties. Moreover, the cellular/molecular mechanisms supporting the detrimental or beneficial features of astrogliosis have been scrutinized to gain insights on possible pharmacological approaches to enhance astrocyte neuroprotective activities.     

去甲斑蝥素对G422脑胶质瘤抑制作用的体内研究

目的:研究去甲斑蝥素(NCTD)体内对脑胶质瘤G422细胞的抑制作用。方法:建立G422细胞小鼠移植瘤模型,将荷瘤小鼠随机分为模型组、CTX阳性对照组及NCTD高、中、低剂量组(100、50、25 mg.kg-1),每组10只,另设10只为正常对照组,正常对照组每日给生理盐水灌胃,CTX和NCTD组采用腹腔注射方式给药,10 d后双抗体夹心ABC-ELISA法测sIL-2R的含量;酶联免疫ELISA法测IFN-γ含量;剥瘤,计算抑瘤率;剥瘤的同时取脾脏,计算脾脏指数;MTT法检测NCTD对荷瘤小鼠脾脏T、B淋巴细胞增殖的影响。结果:NCTD可降低荷瘤小鼠血清sIL-2R含量,提高IFN-γ含量,抑制G422细胞小鼠移植瘤的生长;对脾脏指数影响较少,可促进荷瘤小鼠的T、B淋巴细胞增殖。结论:NCTD体内外可抑制G422细胞生长,并具有免疫调节作用。     

人参三七川芎提取物对增龄和高血压大鼠血管平滑肌细胞的影响

目的 观察和比较增龄与高血压对大鼠主动脉血管平滑肌细胞(vascular smooth muscle cells,VSMCs)的影响及人参、三七、川芎提取物的干预作用。方法 采用原代细胞培养的方法建立大鼠主动脉VSMCs模型,其中增龄实验分5组：青年对照组(Yon组)、老龄组(Old组)、老龄+普罗布考组(Old+Pro组)、老龄+中药低剂量组(Old+Low组)和老龄+中药高剂量组(Old+High组);高血压实验分5组：Wistar-Kyoto对照组(WKY组)、自发性高血压大鼠(spontaneously hypertensive rat,SHR)组、SHR+缬沙坦组(SHR+Val组)、SHR+中药低剂量组(SHR+Low组)和SHR+中药高剂量组(SHR +High组)。采用MTT法检测细胞增殖,免疫细胞化学法检测基质金属蛋白酶-9(MMP-9)表达,RT-PCR和Western blot分别检测过氧化物酶增殖物激活受体γ(peroxisome proliferator activated receptor-γ,PPAR-γ)mRNA和蛋白表达。结果 与Yon组比较,Old组VSMCs增殖水平和MMP-9表达升高,PPAR-γ mRNA和蛋白表达减少,差异均有统计学意义(P<0.05)。与Old组比较,Old+Pro组、Old+High组和 Old+Low组VSMCs增殖水平和MMP-9表达明显降低,PPAR-γ mRNA表达明显增加(均P<0.05),Old+Pro组和Old+Low组PPAR-γ蛋白表达明显增加(均P<0.05)。与WKY组比较,SHR组VSMCs增殖水平和MMP-9表达明显升高,PPAR-γ mRNA和蛋白表达明显减少(均P<0.05);与SHR组比较,SHR+Val组、SHR +High组和SHR+Low组VSMCs增殖水平和MMP-9表达明显降低,PPAR-γ mRNA和蛋白表达增加(均P<0.05)。结论 增龄和高血压均可造成大鼠主动脉VSMCs过度增殖及相关细胞活性因子的表达改变,中药人参、三七、川芎提取物能够降低其增殖水平,减少负性细胞因子的表达以降低增龄和高血压对VSMCs的损害,延缓血管细胞的老化。     

The bark of Betula platyphylla var. japonica inhibits the development of atopic dermatitis-like skin lesions in NC/Nga mice

The bark of Betula platyphylla Sukat. var. japonica Hara (Asian White Birch, AWB) is one of the herbs used in Eastern countries for the treatment of various inflammatory diseases including atopic dermatitis (AD). The present study was performed to examine if and how the bark of AWB inhibits the development of AD-like skin lesions in NC/Nga mice induced by repeated application of picryl chloride (PC). With this aim, we examined the skin symptom severity, itching behavior, serum immunoglobulin (Ig) E level and mRNA expression of cytokines at iliac and cervical lymph nodes in the mice. Oral administration of AWB extracts (25, 100 and 250 mg/kg) to the PC-treated mice inhibited the development of AD-like skin lesions as exemplified by a significant decrease in the total skin severity scores, itching behavior and a decrease in hypertrophy and infiltration of inflammatory cells into dermis. The serum IgE level was also significantly reduced by AWB extract. In the RT-PCR results, the expression of interleukin-4 mRNA was reduced by AWB extract, whereas the expression of interferon-gamma mRNA was not changed. These results suggest that AWB inhibits the development of AD-like skin lesions in NC/Nga mice through the suppression of the T-helper 2 cell response.     

丙型肝炎患者生化变量与细胞因子间的相关性分析

目的：研究丙型肝炎病毒感染后血液生化变量与细胞因子重组人干扰素γ（interferon-1,IFN-γ）、肿瘤坏死因子仪（tumornecrosisfactor,TNF—α）、重组人白介素10（interleukin-10,IL-10）之间的相关性。方法：以66例丙型肝炎患者为材料,利用统计学软件,分析丙型肝炎患者各生化指标之间及与3种细胞因子间的相关性。结果：①除球蛋白（GLO）与TNF—d在0．05置信水平上有较低相关性（r=-0．287,P=0．046）之外,各生化变量与各细胞因子之间无明显相关性。②各生化变量之间,丙氨酸氨基转换酶（ALT）与天门冬酸氨基转换酶（AST）有显著的相关性（r=0．869,P=0）,做除法后（ALT／AST）相关性基本被消除,各变量之间存在微弱互相关性。③除IFN-γ与TNF—α之间存在弱相关性（r=-0．448,P=0．009）之外,各炎症细胞因子之间无明显相关性。结论：各生化指标之间、3种炎症细胞因子之间、各生化变量与3种炎症细胞因子间的相关性均较差。     

术后认知功能障碍治疗的新靶向-γ-氨基丁酸A型受体相关药物

背景 术后认知功能障碍(postoperative cognitive dysfunction,POCD)是一种常见的围术期并发症.γ-氨基丁酸A型(γ-aminobutyricacid type A,GABAA)受体作为一种中枢神经抑制性受体,可能对POCD的发生起着关键性作用.目的 综述以GABAA受体为靶点的相关药物对POCD的影响.内容 与GABAA受体相关的3类药物:激动剂、拮抗剂和反向激动剂,对POCD可分别产生诱发、逆转和改善症状的作用. 趋向 对记忆或者认知功能损害具有改善作用的GABAA受体相关药物,对POCD的治疗具有重大意义,将成为今后POCD的研究热点.     

γ-Rays-generated ROS induce apoptosis via mitochondrial and cell cycle alteration in smooth muscle cells

Abstract

Purpose: γ-rays (IR) cause an increase in intracellular calcium [Ca²⁺], alters contractility and triggers apoptosis via the activation of protein kinase C in intestinal guinea pig smooth muscle cells. The present study investigated the role of the mitochondria in these processes and characterized proteins involved in IR-induced apoptosis.

Materials and methods: Intestinal smooth muscle cells were exposed to 10–50 Gy from a ⁶⁰Co γ-source. Reactive oxygen species (ROS) levels were measured by colourimetry with a fluorescente probe. Protein expression was analyzed by immunoblotting and immunofluorescence.

Results: Apoptosis was inhibited by glutathione, possible by inhibiting the generation or scavenging ROS. Apoptosis was mediated by the mitochondria releasing cytochrome c leading to caspase 3 activation. IR increased the expression of the cyclins A, B2 and E and led to unbalanced cellular growth in an absorption dose-dependent manner. However, radiation did not induce alterations in the mitochondrial ultrastructure or in transmembrane electric potential. In contrast, IR increased the nuclear expression of cytoplasmic proteins and cyclins A and E.

Conclusion: Smooth muscle cells subjected to IR undergo mitochondrial-mediated apoptosis that involves oncoproteins activation and preserves mitochondrial structure. IR also cause alterations in the expression and localization of both pro- and anti-apoptotic proteins.     

Graptopetalum paraguayense and resveratrol ameliorates carboxymethyllysine (CML)-induced pancreas dysfunction and hyperglycemia

Hyperglycemia is associated with advanced glycation end products (AGEs). Recently, AGEs were found to cause pancreatic damage, oxidative stress, and hyperglycemia through the AGE receptor. Carboxymethyllysine (CML) is an AGE but whether it induces pancreatic dysfunction remains unclear. Graptopetalum paraguayense, a vegetable consumed in Taiwan, has been used in folk medicine and is an antioxidant that protects against liver damage. We investigated the protective properties of G. paraguayense 95% ethanol extracts (GPEs) against CML-induced pancreatic damage. The results indicated that resveratrol, GPE, and gallic acid (the active compound of GPE) increased insulin synthesis via upregulation of pancreatic peroxisome proliferator activated-receptor-γ (PPARγ) and pancreatic-duodenal homeobox-1 (PDX-1) but inhibited the expression of CML-mediated CCAAT/enhancer binding protein-β (C/EBPβ), a negative regulator of insulin production. Moreover, resveratrol and GPE also strongly activated nuclear factor-erythroid 2-related factor 2 (Nrf2) to attenuate oxidative stress and improve insulin sensitivity in the liver and muscle of CML-injected C57BL/6 mice and resulted in reduced blood glucose levels. Taken together, these findings suggested that GPE and gallic acid could potentially be used as a food supplement to protect against pancreatic damage and the development of diabetes.