de Rivero Vaccari Juan Pablo, Brand Frank, Adamczak Stephanie, Lee Stephanie W, Perez-Barcena Jon, Wang Michael Y, Bullock M Ross, Dietrich W Dalton, Keane Robert W
Neurological Surgery and the Miami Project to Cure Paralysis, University of Miami Miller School of Medicine, Miami, Florida, USA.
Departments of Physiology and Biophysics, University of Miami Miller School of Medicine, Miami, Florida, USA.
J Neurochem. 2016 Jan;136 Suppl 1(0 1):39-48. doi: 10.1111/jnc.13036. Epub 2015 Mar 1.
Neuroinflammation is a response against harmful effects of diverse stimuli and participates in the pathogenesis of brain and spinal cord injury (SCI). The innate immune response plays a role in neuroinflammation following CNS injury via activation of multiprotein complexes termed inflammasomes that regulate the activation of caspase 1 and the processing of the pro-inflammatory cytokines IL-1β and IL-18. We report here that the expression of components of the nucleotide-binding and oligomerization domain (NOD)-like receptor protein-1 (NLRP-1) inflammasome, apoptosis speck-like protein containing a caspase recruitment domain (ASC), and caspase 1 are significantly elevated in spinal cord motor neurons and cortical neurons after CNS trauma. Moreover, NLRP1 inflammasome proteins are present in exosomes derived from CSF of SCI and traumatic brain-injured patients following trauma. To investigate whether exosomes could be used to therapeutically block inflammasome activation in the CNS, exosomes were isolated from embryonic cortical neuronal cultures and loaded with short-interfering RNA (siRNA) against ASC and administered to spinal cord-injured animals. Neuronal-derived exosomes crossed the injured blood-spinal cord barrier, and delivered their cargo in vivo, resulting in knockdown of ASC protein levels by approximately 76% when compared to SCI rats treated with scrambled siRNA. Surprisingly, siRNA silencing of ASC also led to a significant decrease in caspase 1 activation and processing of IL-1β after SCI. These findings indicate that exosome-mediated siRNA delivery may be a strong candidate to block inflammasome activation following CNS injury. We propose the following signaling cascade for inflammasome activation in peripheral tissues after CNS injury: CNS trauma induces inflammasome activation in the nervous system and secretion of exosomes containing inflammasome protein cargo into cerebral spinal fluid. The inflammasome containing exosomes then fuse with target cells to activate the innate immune response in peripheral tissues. We suggest that these findings may be used to develop new therapeutics to treat the devastating inflammation and cell destruction evoked by CNS injuries. IL-1β and IL-18 = pro-inflammatory cytokines.
神经炎症是机体对多种刺激的有害影响所产生的一种反应，参与脑和脊髓损伤（SCI）的发病机制。中枢神经系统（CNS）损伤后，固有免疫反应通过激活称为炎性小体的多蛋白复合物在神经炎症中发挥作用，这些复合物调节半胱天冬酶-1的激活以及促炎细胞因子白细胞介素-1β（IL-1β）和白细胞介素-18（IL-18）的加工处理。我们在此报告，在中枢神经系统创伤后，脊髓运动神经元和皮质神经元中核苷酸结合寡聚化结构域（NOD）样受体蛋白1（NLRP-1）炎性小体、含半胱天冬酶募集结构域的凋亡斑点样蛋白（ASC）和半胱天冬酶-1的表达显著升高。此外，SCI和创伤性脑损伤患者创伤后脑脊液来源的外泌体中存在NLRP1炎性小体蛋白。为了研究外泌体是否可用于治疗性阻断中枢神经系统中的炎性小体激活，从胚胎皮质神经元培养物中分离出外泌体，并装载针对ASC的小干扰RNA（siRNA），然后将其给予脊髓损伤动物。神经元来源的外泌体穿过受损的血脊髓屏障，并在体内递送其携带的物质，与用乱序siRNA处理的SCI大鼠相比，导致ASC蛋白水平降低约76%。令人惊讶的是，ASC的siRNA沉默还导致SCI后半胱天冬酶-1的激活和IL-1β的加工处理显著减少。这些发现表明，外泌体介导的siRNA递送可能是阻断中枢神经系统损伤后炎性小体激活的有力候选方法。我们提出了中枢神经系统损伤后外周组织中炎性小体激活的以下信号级联反应：中枢神经系统创伤诱导神经系统中的炎性小体激活，并将含有炎性小体蛋白物质的外泌体分泌到脑脊液中。含有炎性小体的外泌体随后与靶细胞融合，以激活外周组织中的固有免疫反应。我们认为，这些发现可用于开发新的疗法，以治疗中枢神经系统损伤引起的毁灭性炎症和细胞破坏。IL-1β和IL-18 = 促炎细胞因子
