Neuropeptides in the pathogenesis of neurocysticercosis

描述（由申请人提供）：脑囊虫病（NCC）是由寄生虫猪带绦虫引起的人类中枢神经系统寄生虫感染。NCC被认为是全世界缉获的主要原因。NCC的癫痫发作是由脑内垂死寄生虫引起的局部肉芽肿反应引起的。癫痫发作的介质尚不清楚，NCC中癫痫发作介质的鉴定可能导致使用特异性拮抗剂进行治疗。神经肽P物质（SP）刺激肉芽肿生长和Th 1细胞因子产生。另一种神经肽，生长抑素，刺激Th 2细胞因子的产生和损害肉芽肿的形成。SP在神经元中引起癫痫样反应，而生长抑素具有抗惊厥特性。根据退化寄生虫的组织学表现，我们将与鼠囊虫病相关的肉芽肿分为4期。早期肉芽肿表达Th 1细胞因子和SP，而Th 2细胞因子和生长抑素仅在晚期表达。初步结果还指出，当将早期肉芽肿提取物注射到大鼠脑中时，可诱导行为性癫痫发作和海马活动增加。用SP受体拮抗剂预处理可抑制上述作用。同样，SP注入大鼠脑内也引起癫痫发作和海马活动的改变，而这种改变可被SP受体拮抗剂或生长抑素完全阻断。我们推测，SP介导和生长抑素抑制肉芽肿反应和癫痫发作的NCC。具体目标1：检验SP和生长抑素调节囊虫病肉芽肿反应的假设。将比较感染的野生型小鼠、SP敲除小鼠（SP KO）、SP受体KO小鼠和生长抑素KO小鼠中的肉芽肿大小、Th 1/Th 2和促炎细胞因子水平。具体目标2：确定SP和生长抑素是否分别负责NCC癫痫发作反应的介导和调节。SP蛋白表达将在NCC癫痫患者的脑活检中进行检查。将来自感染的SP KO和生长抑素KO小鼠的肉芽肿提取物的致癫痫活性与来自野生型小鼠的致癫痫活性进行比较。具体目标3：确定NCC中的癫痫发作是否直接归因于SP和/或间接归因于SP诱导的细胞因子。将在有或无SP、IL-1 β、TNF-α或IL-6抑制或阻断的情况下，检测早期肉芽肿提取物的致癫痫活性。还将检测感染的IL-1 β、TNF-α或IL-6敲除的早期肉芽肿的致癫痫活性。具体目标4：检验生长抑素抑制NCC癫痫发作的假设。将研究早期肉芽肿提取物与或不与生长抑素类似物或SOM拮抗剂的致癫痫活性。这些研究将确定SP和SOM在NCC发病机制中的重要性，并可能导致未来使用SP拮抗剂和SOM类似物作为抗癫痫药物治疗NCC的癫痫发作和其他癫痫发作相关疾病。

DESCRIPTION (provided by applicant): Neurocysticercosis (NCC) is a parasitic infection of the human central nervous system caused by the helminth Taenia solium. NCC is recognized as a leading cause of seizures worldwide. Seizures in NCC are evoked by localized granulomatous responses to dying parasites in the brain. The mediators of the seizures are unknown, identification of seizure mediator(s) in NCC may result in treatment with specific antagonists. The neuropeptide substance P (SP) stimulates granuloma growth and Th1 cytokine production. Another neuropeptide, somatostatin, stimulates Th2 cytokine production and impairs granuloma formation. SP evokes epileptiform responses in neurons, whereas, somatostatin has anticonvulsant properties. We divided granulomas associated with murine cysticercosis into 4 stages based on the histologic appearance of the degenerating parasite. Early stage granulomas expressed Th1 cytokines and SP, whereas Th2 cytokines and somatostatin were only expressed in later stages. Preliminary results also noted that behavioral seizures and increased hippocampal activity were induced when extracts from early granulomas were injected into brain of rats. Pretreatment with SP receptor antagonist inhibited these effects. Similarly, injection of SP into rat brain also induced seizures and altered hippocampal activity that was completely blocked by pretreatment with SP receptor antagonist or somatostatin. We hypothesize that SP mediates and somatostatin inhibits the granulomatous response and seizures in NCC. Specific aim 1: To test the hypothesis that SP and somatostatin modulate granulomatous responses in cysticercosis. Granuloma size, Th1/Th2 and pro-inflammatory cytokine levels in infected, wildtype mice, SP knockout mice (SP KO), SP receptor KO mice and somatostatin KO mice will be compared. Specific aim 2: To determine if SP and somatostatin are respectively responsible for the mediation and modulation of seizure responses in NCC. SP protein expression will be examined in brain biopsies from NCC patients with seizures. Epileptogenic activity of granuloma extracts from infected, SP KO and somatostatin KO mice will be compared to that from wildtype mice. Specific aim 3: To determine if seizures in NCC are directly due to SP and/or indirectly due to SP induced cytokines. Epileptogenic activity of early granuloma extracts will be tested with or without inhibition or blocking of SP, IL-1beta, TNF-alpha or IL-6. Also epileptogenic activity of early granulomas from infected IL-1beta, TNF-alpha or IL-6 knockouts will be tested. Specific aim 4: To test the hypothesis that somatostatin inhibits seizures in NCC. Epileptogenic activity of early granuloma extracts with or without somatostatin analogues or SOM antagonist will be studied. These studies will determine the importance of SP and SOM in pathogenesis of NCC, and may lead to future use of SP antagonist and SOM analogues as anti-epileptic agents for treatment of seizures in NCC and other seizure related diseases.