背景:创伤性脑损伤(TBI)会引起神经炎症,并可能导致长期的神经功能障碍,即使在轻度TBI(mTBI)的情况下。尽管这种疾病负担很大,对TBI的细胞机制的不完全理解阻碍了TBI的管理。鞘脂(SPL)及其代谢物已成为与组织损伤相关的生物过程的关键协调器,神经炎症,和炎症的解决。迄今为止,尚无研究调查动物模型或人类病例中TBI后立即发生的鞘脂综合分布变化。在这项研究中,在mTBI后的小鼠的脑组织和血浆中的急性期检查鞘脂代谢物组成。
方法:将野生型小鼠暴露于气流介导的mTBI,将左侧颅骨的爆炸暴露设置为50-psi,将0-psi指定为假。在TBI后1、3和7天的急性期,通过液相色谱-质谱法分析了脑组织和血浆中的鞘脂分布。同时,使用定量逆转录-聚合酶链反应分析脑组织内鞘脂代谢标志物的基因表达.通过非参数t检验(Mann-Whitney检验)和通过多重比较的Tukey校正来确定显著性(P值)。
结果:在TBI后的脑组织中,1)酸性鞘磷脂酶(aSMase)在1天和3天显着升高,2)中性鞘磷脂酶(nSMase)在7天,3)1天的神经酰胺-1-磷酸水平,和4)在7天的单己糖神经酰胺(MHC)和鞘氨醇。在单个物种中,研究发现,在第1天,C18:0增加,C24:1神经酰胺(Cer)减少;在第3天,C20:0MHC增加;在第7天,MHCC18:0减少,MHCC24:1,鞘磷脂(SM)C18:0和C24:0增加。此外,许多鞘脂代谢基因在1天升高,随后在TBI后3天减少和7天缺席。在TBI后血浆中,1)第1天Cer和MHCC22:0显着降低,MHCC16:0增加;2)长链CerC24:1显着增加,MHC和SM中CerC24:0和C22:0显着降低3天;3)所有类别的SPL中C22:0显着增加(Cer,MHC和SM)以及在第7天时CerC24:1,MHCC24:1和MHCC24:0的降低。
结论:鞘脂代谢产物组成的变化,特别是鞘磷脂酶和短链神经酰胺,可能有助于TBI早期神经炎性事件的诱导和调节,提出新诊断的潜在目标,预后,以及未来的治疗策略。
BACKGROUND: Traumatic brain injury (TBI) causes neuroinflammation and can lead to long-term neurological dysfunction, even in cases of mild TBI (mTBI). Despite the substantial burden of this disease, the management of TBI is precluded by an incomplete understanding of its cellular mechanisms. Sphingolipids (SPL) and their metabolites have emerged as key orchestrators of biological processes related to tissue injury, neuroinflammation, and inflammation resolution. No study so far has investigated comprehensive sphingolipid profile changes immediately following TBI in animal models or human cases. In this study, sphingolipid metabolite composition was examined during the acute phases in brain tissue and plasma of mice following mTBI.
METHODS: Wildtype mice were exposed to air-blast-mediated mTBI, with blast exposure set at 50-psi on the left cranium and 0-psi designated as Sham. Sphingolipid profile was analyzed in brain tissue and plasma during the acute phases of 1, 3, and 7 days post-TBI via liquid-chromatography-mass spectrometry. Simultaneously, gene expression of sphingolipid metabolic markers within brain tissue was analyzed using quantitative reverse transcription-polymerase chain reaction. Significance (P-values) was determined by non-parametric t-test (Mann-Whitney test) and by Tukey\'s correction for multiple comparisons.
RESULTS: In post-TBI brain tissue, there was a significant elevation of 1) acid sphingomyelinase (aSMase) at 1- and 3-days, 2) neutral sphingomyelinase (nSMase) at 7-days, 3) ceramide-1-phosphate levels at 1 day, and 4) monohexosylceramide (MHC) and sphingosine at 7-days. Among individual species, the study found an increase in C18:0 and a decrease in C24:1 ceramides (Cer) at 1 day; an increase in C20:0 MHC at 3 days; decrease in MHC C18:0 and increase in MHC C24:1, sphingomyelins (SM) C18:0, and C24:0 at 7 days. Moreover, many sphingolipid metabolic genes were elevated at 1 day, followed by a reduction at 3 days and an absence at 7-days post-TBI. In post-TBI plasma, there was 1) a significant reduction in Cer and MHC C22:0, and an increase in MHC C16:0 at 1 day; 2) a very significant increase in long-chain Cer C24:1 accompanied by significant decreases in Cer C24:0 and C22:0 in MHC and SM at 3 days; and 3) a significant increase of C22:0 in all classes of SPL (Cer, MHC and SM) as well as a decrease in Cer C24:1, MHC C24:1 and MHC C24:0 at 7 days.
CONCLUSIONS: Alterations in sphingolipid metabolite composition, particularly sphingomyelinases and short-chain ceramides, may contribute to the induction and regulation of neuroinflammatory events in the early stages of TBI, suggesting potential targets for novel diagnostic, prognostic, and therapeutic strategies in the future.