RESUMO
Only a few types of inflammasomes have been described in central nervous system cells. Among these, the absent in melanoma 2 (AIM2) inflammasome is primarily found in neurons, is highly specific and can be activated only by double-stranded DNA. Although it has been demonstrated that the AIM2 inflammasome is activated by poly(deoxyadenylic-deoxythymidylic) acid sodium salt and leads to pyroptotic neuronal cell death, the role of AIM2 inflammasome-mediated pyroptosis in early brain injury (EBI) after subarachnoid haemorrhage (SAH) has rarely been studied. Thus, we designed this study to explore the mechanism of gasdermin D(GSDMD)-induced pyroptosis mediated by the AIM2 inflammasome in EBI after SAH. The level of AIM2 from the cerebrospinal fluid (CSF) of patients with SAH was detected. The pathway of AIM2 inflammasome-mediated pyroptosis, the AIM2/Caspase-1/GSDMD pathway, was explored after experimental SAH in vivo and in primary cortical neurons stimulated by oxyhaemoglobin (oxyHb) in vitro. Then, we evaluated GSDMD-induced pyroptosis mediated by the AIM2 inflammasome in AIM2 and caspase-1- deficient mice and primary cortical neurons generated through lentivirus (LV) knockdown. Compared with that of the control samples, the AIM2 level in the CSF of the patients with SAH was significantly increased. Pyroptosis-associated proteins mediated by the AIM2 inflammasome were significantly increased in vivo and in vitro following experimentally induced SAH. After AIM2 and caspase-1 were knocked down by an LV, GSDMD-induced pyroptosis mediated by the AIM2 inflammasome was alleviated in EBI after SAH. Intriguingly, when caspase-1 was knocked down, apoptosis was significantly suppressed via impeding the activation of caspase-3. GSDMD-induced pyroptosis mediated by the AIM2 inflammasome may be involved in EBI following SAH. The inhibition of AIM2 inflammasome activation caused by knocking down AIM2 and caspase-1 alleviates GSDMD-induced pyroptosis in EBI after SAH.
Assuntos
Lesões Encefálicas/metabolismo , Proteínas de Ligação a DNA/líquido cefalorraquidiano , Inflamassomos/metabolismo , Peptídeos e Proteínas de Sinalização Intracelular/metabolismo , Neurônios/metabolismo , Proteínas de Ligação a Fosfato/metabolismo , Piroptose/genética , Hemorragia Subaracnóidea/metabolismo , Animais , Lesões Encefálicas/genética , Caspase 1/genética , Caspase 1/metabolismo , Caspase 3/metabolismo , Células Cultivadas , Proteínas de Ligação a DNA/metabolismo , Humanos , Peptídeos e Proteínas de Sinalização Intracelular/genética , Camundongos , Camundongos Endogâmicos C57BL , Microscopia Eletrônica de Varredura , Neurônios/ultraestrutura , Proteínas de Ligação a Fosfato/genética , Piroptose/fisiologia , Hemorragia Subaracnóidea/genéticaRESUMO
Abundant erythrocytes remain and lyse partially in the subarachnoid space after severe subarachnoid haemorrhage (SAH). But the effect of subarachnoid erythrocyte lysate on brain injury is still not completely clear. In this study, autologous erythrocytes (the non-lysate group) and their lysate (the lysate group) were injected separately into the cistern magna of rabbits to induce a model of experimental SAH, although the control group received isotonic sodium chloride solution instead of erythrocyte solution. Results showed that vasospasm of the basilar artery was observed at 72 h after experimental SAH, but there was no significant difference between the non-lysate group and the lysate group. Brain injury was more severe in the lysate group than in the non-lysate group. Meanwhile, the levels of peroxiredoxin 2 (Prx2), IL-6 and TNF-α in brain cortex and in CSF were significantly higher in the lysate group than those in the non-lysate group. These results demonstrated that brain injury was more likely to be caused by erythrocyte lysate than by intact erythrocytes in subarachnoid space, and inflammation response positively correlated with Prx2 expression might be involved in mechanism of brain injury after SAH.