Reactive astrocytes from gliotic capsule

描述（由申请人提供）：在大脑中“异物”周围形成的胶质囊是一个重要的，尽管被忽视的生物系统。虽然总体上是有益的，但胶质囊形成了一个潜在的有害组织团块，有助于脑肿胀和团块效应，并可能保护外来细胞免受免疫系统的监视。我们发现，在大鼠和人类的各种病理条件下，胶质胶质膜内区的反应性星形胶质细胞（R1星形胶质细胞）表达一种新的由surl调节的阳离子通道，即ncca - atp通道，该通道直接控制细胞活力：打开该通道与坏死细胞死亡有关，关闭该通道与保护细胞免受能量耗尽引起的死亡有关。这一发现可以用于R1星形胶质细胞的药理学操作，不仅可以提高对胶质瘤囊的基本细胞生物学的理解，而且还可以用于操纵胶囊形成以改善患者治疗的技术。在本提案的目标1中，我们将扩展初步数据，表明抑制NCca-ATPchannel可保护R1星形胶质细胞免于细胞死亡。我们将研究两种抑制通道的方法，磺脲、格列本脲和雌激素。在Aim 1的第一部分，我们将详细研究雌激素阻断通道活性的机制，在初步数据的基础上，我们发现雄性和雌性的ncca - atp通道活性通过非基因组信号通路被雌激素抑制。在Aim 1的第二部分，我们将使用雌激素和格列本脲在体内研究通道抑制对胶质囊形成和脑水肿发展的影响。在Aim 2中，我们将扩展初步数据，表明通过二氮氧化合物输注选择性杀死R1星形胶质细胞，在体外导致R1星形胶质细胞的通道打开和坏死死亡，导致整体星形胶质反应的扩大和大量中性粒细胞的募集。我们将详细研究这种反应，并评估小胶质细胞和细胞因子在这种对损伤的改变反应中的作用。在Aim 3中，我们将扩展初步数据，表明NCca-ATPchannel的体外表达需要缺氧条件，并且在体内发现该通道的胶质囊内区是缺氧的，这表明缺氧/HIF1在通道表达中起关键作用。我们将通过注入反义寡脱氧核苷酸抑制HIF-1的表达来研究HIF-1的作用。总之，我们期望这些研究将建立在我们最近发现的新的surl调控的ncca - atp通道的基础上，并将有助于阐明R1星形胶质细胞在胶质囊内区的功能。

DESCRIPTION (provided by applicant): The gliotic capsule that forms around a "foreign body" in the brain is an important, albeit neglected, biological system. Although beneficial overall, the gliotic capsule forms a potentially harmful mass of tissue that contributes to brain swelling and mass effect, and that may shelter foreign cells from surveillance by the immune system. We have found that, in a variety pathological conditions in both rats and humans, reactive astrocytes (R1 astrocytes) in the inner zone of the gliotic capsule express a novel SURl-regulated cation channel, the NCca-ATPchannel, and that this channel directly controls cell viability: opening the channel is associated with necrotic cell death and closing the channel is associated with protection from cell death induced by energy depletion. This discovery can be exploited to allow pharmacological manipulation of R1 astrocytes, leading not only to improved understanding of the basic cellular biology of the gliotic capsule, but also to techniques that will allow manipulation of capsule formation to improve treatment of patients. In Aim 1 of this proposal, we will expand on preliminary data showing that inhibiting the NCca-ATPchannel protects R1 astrocytes from cell death. We will look at 2 ways to inhibit the channel, with the sulfonylurea, glybenclamide, and with estrogen. In the first part of Aim 1, we will examine in detail the mechanism by which estrogen blocks channel activity, building on preliminary data in which we found that activity of the NCca-ATPchannel in both males and females is inhibited by estrogen via a non-genomic signaling pathway. In the second part of Aim 1, we will use estrogen and glybenclamide to examine the effect of channel inhibition on formation of the gliotic capsule and on development of cerebral edema in vivo. In Aim 2, we will expand on preliminary data showing that selective killing of R1 astrocytes by diazoxide infusion, which in vitro causes channel opening and necrotic death of R1 astrocytes, results in expansion of the overall astrogliotic response and recruitment of enormous numbers of neutrophils. We will study this response in detail and assess the role of microglia and cytokines in this altered response to injury. In Aim 3, we will expand on preliminary data showing that expression of the NCca-ATPchannel in vitro requires conditions of hypoxia, and that the inner zone of the gliotic capsule where the channel is found in vivo is hypoxic, suggesting a critical role for hypoxia/HIF1 in channel expression. We will study the role of HIF-1 by inhibiting its expression using antisense oligodeoxynucleotide infusion. Overall, we expect that these studies will build on our recent discovery of the novel SURl-regulated NCca-ATPchannel, and will help to elucidate the function of R1 astrocytes in the inner zone of the gliotic capsule.