Expression of β-1,4-Galactosyltransferase-I in Rat during Inflammation

β-1,4-Galactosyltransferase-I (β-1,4-GalT-I) which is one of the best-studied glycosyltransferases, plays a key role in the synthesis of selectin ligands such as sialy Lewis (sLe ^x ) and sulfated sLe ^x . Previous studies showed that inflammatory responses of β-1,4-GalT-I-deficient mice were impaired because of the defect in selectin-ligand biosynthesis. However, the expression of β-1,4-GalT-I during inflammation and its biological function remains to be elucidated. Real-time PCR showed that intraperitoneal administration of LPS strongly induced β-1,4-GalT-I mRNA expression in the lung, heart, liver, spleen, kidney, lymph node, hippocampus, and testis, as well as in the cerebral cortex. In the rat lung, liver and testis, LPS stimulation of β-1,4-GalT-I mRNA expression is time-dependent and biphasic. Lectin-fluorescent staining with RCA-I showed that LPS induced expression of galactose-containing glycans in rat lung and liver to the higher lever. Morphology analysis observed that galactose-containing glycans and β-1,4-GalT-I mRNA was mostly expressed in neutrophils, macrophages and endothelial cells. These findings indicated that β-1,4-GalT-I may play an important role in the inflammation reaction.     

Lipopolysaccharide Induced Upregulation of β-1,4-Galactosyltransferase-I in Schwann cell

β4 Galactosylation of glycoproteins is one of the most important post-translational modifications. Recent studies have demonstrated that aberrant galactosylation associates with some inflammation diseases. β-1,4-galactosyltransferase-I (β-1,4-GalT-I), which transfers galactose to the terminal N-acetylglucosamine of N- and O-linked glycans in a β-1,4- linkage, considered to be the major galactosyltransferse among the seven members of the subfamily responsible for β4 galactosylation. In the present study, we investigated the expression of β-1,4-GalT-I in Schwann cells under Lipopolysaccharide (LPS) treatment. RT-PCR revealed that the β-1,4-GalT-I mRNA was significant increased as early as 2 h after LPS stimulation. Immunofluorescence showed that β-1,4-GalT-I was located in Golgi apparatus and membrane of Schwann cells. With the 1 μg/ml LPS treatment, expression levels of β-1,4-GalT-I was much higher compared with control group. In addition, lectin blot indicated that the β4 galactosylation of glycoproteins such as integrin α5 was enhanced, which may due to the induced β-1,4-GalT-I expression. These results suggested that β-1,4-GalT-I may play an important role in adhesion and migration of Schwann cells during inflammation.     

Temporal–spatial expression of ENOLASE after acute spinal cord injury in adult rats

ENOLASE enzymes are abundantly expressed, cytosolic carbon–oxygen lyases known for their role in glucose metabolism. Recent accumulation of evidence revealed that, in addition to its glycolytic function, enolase is also associated with ischemia, hypoxia and to be a neurotrophic factor. To analysis the certain expression and biological function in central nervous system, we performed an acute spinal cord contusion injury model in adult rats. Western blot analysis indicated a marked upregulation of ENOLASE after spinal cord injury (SCI). Immunohistochemistry revealed wide distribution of enolase in spinal cord, including neurons and glial cells. Double immunofluorescent staining for proliferating cell nuclear antigen and phenotype-specific markers showed increases of enolase expression in proliferating microglia and astrocytes. Our data suggest that enolase may be implicated in the proliferation of microglia and astrocytes after SCI.     

电针刺激对脊髓挫伤模型大鼠神经细胞凋亡的影响

BACKGROUND: Electroacupuncture has promoting effects on the functional recovery of the injured spinal cord, can decrease pain, and elevate postoperative effect after acute spinal cord contusion.  OBJECTIVE: To observe the effect of electroacupuncture on apoptosis in the injured site after spinal cord contusion, and analyze its neuroprotective effects on neurological function in rats with spinal cord contusion. METHODS: A total of 66 adult female Sprague-Dawley rats were randomly divided into: sham surgery group (n=20), spinal cord contusion group (n=20), electroacupuncture stimulation group (n=20) because six rats were excluded due to modeling failure and death. Before model establishment, at 1, 3 days, 1, 2, 3 and 4 weeks after model establishment, motor functions were evaluated by BBB score and the inclined plate test. At 3 days after model establishment, apoptosis of nerve cells could be detected in the site of injury in each experimental group using TUNEL assay. mRNA and protein expression of bax, bcl-2 and caspase-3 was detected surrounding the injury site using RT-PCR and western blot assay. Morphological changes in the site of injury could be observed using hematoxylin-eosin staining. The regeneration of nerve fibers was observed using HRP tracing.  RESULTS AND CONCLUSION: (1) Motor function score was significantly increased at various time points in the 2nd week of treatment in the electroacupuncture stimulation group than in the spinal cord contusion group (P < 0.05). (2) Apoptotic index was significantly lower in the electroacupuncture stimulation group than in the spinal cord contusion group at 3 days after model establishment (P < 0.05). (3) mRNA and protein expression of bax and caspase-3 was significantly lower in the electroacupuncture stimulation group than in the spinal cord contusion group at 72 hours (P < 0.05); bcl-2 gene and protein expression was significantly higher (P < 0.05). (4) The number of HRP-positive nerve fibers was highest in the sham surgery group, followed by electroacupuncture stimulation group, and lowest in the spinal cord contusion group at 4 weeks (P < 0.05). Results indicated that electroacupuncture plays a protective role on the spinal cord contusion by reducing apoptosis of nerve cells at the site of injury.      

Tumor Necrosis Factor-α Up-Regulates the Expression of β1,4-Galactosyltransferase-I in Human Fibroblast-like Synoviocytes

β1,4-Galactosyltransferase-I (β1,4-GalT-I), which transfers galactose to the terminal N-acetylglucosamine of N- and O-linked glycans in a β1,4-linkage, is considered to be the major galactosyltransferase among the seven members of the subfamily responsible for β4 galactosylation. We previously reported, for the first time, that β1,4-GalT-I may play an important role in the inflammatory processes in synovial tissue of patients with rheumatoid arthritis (RA). In this study, we analyzed whether β1,4-GalT-I expression correlates with the expression of tumor necrosis factor-α (TNF-α) in RA. We show firstly the overexpression and co-localization of β1,4-GalT-I and TNF-α in synovial tissue of RA patients. Then, lipopolysaccharide (LPS) induces β1,4-GalT-I mRNA up-regulation in fibroblast-like synoviocytes (FLSs) through endogenous TNF-α overexpression. In addition, we observed that not only endogenous TNF-α but also exogenous TNF-α induced β1,4-GalT-I mRNA production in FLSs, and TNF-α-knockdown reverses the up-regulation of β1,4-GalT-I in FLSs induced by LPS or TNF-α. These results suggest that TNF-α contributes to the up-regulation of β1,4-GalT-I mRNA in human FLSs.     

RNA-Seq筛选脊髓损伤后的差异基因及部分基因功能分析

目的应用RNA-Seq技术分析脊髓损伤后不同阶段基因表达差异情况。方法使用IH脊髓打击仪制备脊髓损伤模型,SD大鼠48只随机分成两组,假手术组和实验组,实验组分别于损伤后1d、4d和7d取材。运用RNA-Seq技术筛选脊髓损伤后不同时间点的差异表达基因,对差异基因进行表达模式分析,功能注释,通路分析等,筛选出血红素氧化酶1(Hmox1)等感兴趣基因进行mRNA和蛋白水平的验证及功能分析。结果 RNA-Seq结果表明,与假手术组相比,脊髓损伤后1d、4d和7d发生显著变化的基因分别有944、1362和1421个。上述差异基因在损伤后不同时间点的变化趋势大致可分为8种形式。Real-time PCR结果显示,Hmox1、尿激酶型纤溶酶原激活剂(Plau)、纤溶酶原激活物抑制剂(Serpine1)和中性粒细胞胞质因子(Ncf2)的表达变化与RNA-Seq测序结果基本一致。Western blotting结果显示,脊髓损伤后Hmox1的蛋白表达变化趋势与核酸水平一致;免疫组织化学结果显示,损伤之后Hmox1主要表达于脊髓组织的神经元中。结论 RNA-Seq技术能高效分析脊髓损伤后的差异基因,从大量差异基因中筛选出感兴趣基因的验证和功能分析为阐述脊髓损伤的分子机制提供了部分资料。     

FTY720 improves functional recovery after spinal cord injury by primarily nonimmunomodulatory mechanisms

Spinal cord injury (SCI) is an incapacitating injury that can result in limited functional recovery. We have previously shown increases in the lysophospholipid mediator, sphingosine-1-phosphate (S1P), in the spinal cord after contusion injury. To apply S1P receptor modulation to the treatment of SCI, we examined the therapeutic effects of FTY720, an S1P receptor agonist, on locomotor recovery after SCI in mice. Oral administration of FTY720 shortly after contusion SCI significantly improved motor function recovery, as assessed by both Basso Mouse Scale scores and Rotarod Performance test results. FTY720 induced lymphopenia and reduced T-cell infiltration in the spinal cord after SCI but did not affect the early infiltration of neutrophils and the activation of microglia. In addition, plasma levels and mRNA expression of inflammatory cytokines in the spinal cord after SCI were not attenuated by FTY720. Vascular permeability and astrocyte accumulation were both decreased by FTY720 in the injured spinal cord. The therapeutic effects of FTY720 were not solely dependent on immune modulation, as confirmed by the demonstration that FTY720 also ameliorated motor function after SCI in mice with severe combined immunodeficiency. Finally, the S1P(1) receptor agonist, SEW2871, partly mimicked the therapeutic effect of FTY720. Our data highlight the importance of immune-independent functions of FTY720 in decreasing vascular permeability and astrogliosis in the injured spinal cord and promoting locomotor function recovery after SCI.     

The Functional Interaction Between CDK11p58 and β-1,4-Galactosyltransferase I Involved in Astrocyte Activation Caused by Lipopolysaccharide

Glial cells are mediating the main activation of the central nervous system (CNS), being astrocytes the mayor glial cells in the brain. Glial activation may result beneficial since it could promote tissue repair and pathogen elimination. However, excessive glial activation mechanism can also have do harm to the tissue. β-1,4-Galactosyltransferase I (β-1,4-GalT-I) is a key inflammatory mediator that participates in the initiation and maintenance of inflammatory reaction in some diseases. Moreover, CDK11(p58) has been reported to be associated with β-1,4-GalT-I. We have found that CDK11(p58) and β-1,4-GalT-I are induced in lipopolysaccharide (LPS)-challenged rat primary astrocytes in a affinis dose- and time-dependent manner. CDK11(p58) regulates the expression of β-1,4-GalT-I by interacting with it. After the knockdown of CDK11(p58) expression, the expression of β-1,4-GalT-I decreases, and astrocyte activation downregulates. Inversely, the expression of β-1,4-GalT-I increases, and astrocyte activation enhances due to the overexpression of CDK11(p58). Knockdown of β-1,4-GalT-I reduces the activation potentiation caused by the overexpression of CDK11(p58), illustrating the function of CDK11(p58) to promote astrocyte activation depends on β-1,4-GalT-I. The interaction between CDK11(p58) and β-1,4-GalT-I to upregulate astrocyte activation is related to activating p38 and JNK pathways. These findings indicated that the functional interaction between CDK11(p58) and β-1,4-GalT-I may play an important role during astrocyte activation after LPS administration.     

β-1,4-Galactosyltransferase-I activates proliferation and participates in intercellular contacts of lymphocytes

Beta-1,4-galactosyltransferase I (β-1,4-GalT-I) mediates several biological mechanisms as a key enzyme in glycobiology, but the role of β-1,4-GalT-I in immune system remains unclear. We conducted experiments to investigate whether β-1,4-GalT-I is participating in the activation of Jurkat T cell and intercellular contacts formed by co-incubation of Jurkat and Raji cells in the presence of the superantigen staphylococcal enterotoxin B (SEB). Jurkat cells were also activated by CD3/CD28 co-stimulation in order to examine the expression pattern and cellular distribution of β-1,4-GalT-I upon stimulation. Here we found that β-1,4-GalT-I expression was enhanced and rearranged on the cell surface of activated Jurkat cells. Further, immunofluorescence staining assays revealed that β-1,4-GalT-I co-aggregated with CD3 and CD28 molecules in the junction sides of Jurkat and SEB pulsed Raji cells. Our study also showed that silencing of β-1,4-GalT-I inhibited Jurkat activated Raji cell conjugations and reduced the proliferation rate of activated Jurkat cells. Our data provide evidence that β-1,4-GalT-I plays a role in activation of Jurkat T lymphocytes and participates in intercellular contact formation.     

SB203580, a p38 mitogen-activated protein kinase inhibitor,fails to improve functional outcome following a moderate spinal cord injury in rat

We examined the spatial and temporal expression patterns of active p38 mitogen-activated protein kinase (MAPK), an important regulator of immune cell function, following spinal cord injury (SCI). We further assessed whether administration of SB203580, an inhibitor of p38 MAPK activity, would reduce inflammation, improve tissue sparing, and improve functional outcome after SCI. Adult Wistar rats were subjected to a T9/10 SCI contusion of moderate severity and killed at several time points after injury, whereas sham-injured (control) animals only received a laminectomy. In control animals, active p38 MAPK expression was primarily localized to resting microglia within the spinal cord. Over the first 24 h after SCI, a continuing increase in active p38 MAPK expression was evident in neutrophils and activated microglia (OX42+) surrounding the spinal lesion site. At 15 days post-injury, active p38 MAPK was localized to macrophages (ED1+) that now dominated the lesion site. In addition, active p38 MAPK was localized to macrophages within white matter fiber tracts undergoing degeneration, several segments rostral and caudal to the injury site, which persisted for at least 6 weeks. Overall, our results demonstrate that active p38 MAPK is increased within resident and invading immune cells after SCI contusion injury and, therefore, may be an important target to regulate the inflammatory cascade after SCI. However, intrathecal application of SB203580 failed to improve functional outcome after a moderate SCI contusion.     

Shh/Gli1信号参与小鼠脊髓损伤后血-脊髓屏障渗透性改变及运动功能恢复

目的:探讨sonic hedgehog/Gli1(Shh/Gli1)信号在小鼠脊髓损伤后病理变化及运动功能恢复中的作用。方法:成年雄性C57野生型、Gli1lz和Gli1lz/lz小鼠行T8节段脊髓夹伤及假手术。Gli1lz小鼠脊髓损伤及假手术后3 d行X-gal染色;7 d行Shh/PDGFr-α、Shh/GFAP、LacZ/GFAP染色,观察Shh/Gli1信号在小鼠脊髓损伤后的激活。C57野生型和Gli1lz/lz小鼠脊髓夹伤后7 d行GFAP染色和实时定量RT-PCR,观察星形胶质细胞反应;术后14 d尾静脉注射伊文氏兰观察血-脊髓屏障改变;术后1、3、5 d和7 d行BMS评分评价小鼠后肢运动功能。结果:脊髓损伤7 d后,损伤区Shh表达升高;Shh/Gli1信号报告基因LacZ表达升高,主要表达于反应性星形胶质细胞;免疫组织化学及实时定量RT-PCR结果显示Gli1基因敲除不影响脊髓损伤后GFAP表达;伊文氏兰染色及其定量分析显示Gli1lz/lz小鼠脊髓损伤后脊髓组织伊文氏兰外渗增加。BMS评分显示Gli1lz/lz小鼠运动功能恢复显著差于野生型小鼠。结论:Shh/Gli1信号在小鼠脊髓损伤后激活,可能参与脊髓损伤后血-脊髓屏障渗透性的改变,并影响脊髓损伤后的运动功能恢复。     

HCG induces β1,4-GalT I expression and promotes embryo implantation

Embryo implantation is regarded as a critical physiological process for the success of pregnancy. There are so many reports on the research of human chorionic gonadotropin (HCG) in artificial insemination, but the impact of HCG on endometrial receptivity has not been elucidated. Beta1, 4-Galactosyltransferase-I (β1,4-GalT-I) is ubiquitously expresses in human tissues with the exception of the brain. It not only transfers galactose from UDP-galactoside to GlcNAc to form Galβl,4-GlcNAc, but plays crucial role as cell adhesion molecule by recognizing and adhering other extracellular matrix and galactose of cell surface glycoprotein and glycolipid in cancer cells invasion and migration. The process of the embryos implantation is very similar to tumor invasion, so many biological factors participate in the tumor invasion also play a role in embryo implantation. We hypothesize that β1,4-GalT-I may take part in embryo implantation. In this study, we demonstrated that the over expression of β1,4-GalT-I was induced by HCG in RL95-2 cells. Moreover, the expression of some molecules, such as TIMP-1, LN and MMPs could be regulated by engineered expression of β1,4-GalT-I and therefore lead to the significantly alteration of adhesion capability of RL95-2 cells, even result in reduced adhesive ability between JAR cells and RL95-2 cells. Furthermore, our results indicated that HCG can obviously increase the EGFR signaling pathways-dependent molecular expression through β1,4-GalT-I, HCG also improved the adhesive ability between JAR cells and RL95-2 cells (P < 0.01). Taken together, our data suggested that HCG provides a mechanism to bridge embryo to endometrium through β1,4-GalT.     

β1,4-galactosyltransferase-I in synovial tissue of collagen-induced rat model of rheumatoid arthritis

β1,4-galactosyltransferase-I (β1,4-GalT-I), which is one of the best-studied glycosyltransferases, plays a key role in the synthesis of selectin ligands such as sialyl Lewis (sLe^x) and sulfated sLe^x. Previous studies showed that inflammatory responses of β1,4-GalT-I-deficient mice were impaired because of the defect in selectin-ligand biosynthesis. However, the expression of β1,4-GalT-I and its biological function in rheumatoid arthritis (RA) remain to be elucidated. The mRNA and protein expression of β1,4-GalT-I increased in synovial tissue of the RA group compared with the Normal group at 10d and 15d after collagen-induced. Double staining indicated β1,4-GalT-I overlapped with macrophage-like synoviocytes (MLSs), fibroblast-like synoviocytes (FLSs), neutrophils and tumor necrosis factor-α (TNF-α). Moreover, β1,4-GalT-I mRNA in FLSs in vitro was affected in a dose- and time-dependent manner in response to TNF-α stimulation. ELISA revealed that expression of TNF-α was attenuated in FLSs in vitro treated with β1,4-GalT-I-Ab. We therefore suggest that β1,4-GalT-I may play an important role in the inflammation process of RA synovial tissue, which would provide the foundation for further researching into the concrete mechanism of β1,4-GalT-I in RA.     

β-1,4半乳糖基转移酶-I在钳夹伤后大鼠坐骨神经中表达的变化

为了观察β-1,4-半乳糖基转移酶-I(β-1,4-galactosyltransferase-I,β-1,4-GalT-I)在正常和钳夹伤后大鼠坐骨神经中表达的变化,本研究采用RT-PCR方法,从小鼠坐骨神经中特异性地扩增β-1,4-GalT-I cDNA片段并将其克隆到pGEM-T载体。采用体外转录的方法合成地高辛标记的正、反义β-1,4-GalT-I RNA探针。通过原位杂交和图像分析的方法,观察β-1,4-GalT-I mRNA在正常和夹伤大鼠坐骨神经中的表达及其变化。结果表明:β-1,4-GalT-I mRNA在大鼠坐骨神经的髓鞘中表达,在夹伤坐骨神经后1~2d,β-1,4-GalT-I mRNA在坐骨神经的表达最高,于夹伤后1周开始下降,在夹伤后1个月恢复至正常水平。上述结果提示坐骨神经夹伤后β-1,4-GalT-I mRNA的表达发生变化,并且主要表达在坐骨神经的Schwann细胞。本研究结果为进一步分析β-1,4-GalT-I在周围神经再生中的调控机制奠定了基础。     

Interleukin-17 deficiency improves locomotor recovery and tissue sparing after spinal cord contusion injury in mice

Following the initial impact, spinal cord injury (SCI) triggers a number of inflammatory responses which can exacerbate tissue damage in the cord and impair functional recovery. The involvement of several pro-inflammatory cytokines in the secondary degenerative mechanisms of SCI has been well established, although the role of interleukin-17 (IL-17) remains unclear. In the present study, we used IL-17 knockout (KO) and C57BL/6J wildtype (WT) mice to investigate the effects of IL-17 deficiency on locomotor recovery, lesion size, glial activation and inflammatory cell response following spinal cord contusion injury. Our results show that compared to WT mice, IL-17 KO mice had a significantly smaller lesion size, corresponding with significantly improved locomotor functional recovery following SCI. At 6 weeks after injury, recruitment of B cells, dendritic cells and neutrophils was significantly lower in IL-17 KO than WT mice, however there was no difference in the presence of activated microglia and reactive astrocytes, in the injured spinal cord. These findings suggest that IL-17 is a mediator of secondary degeneration, which contributes to neuroinflammation and hinders functional recovery, though its actions do not affect glial activation following SCI.     

突触后密度蛋白95在大鼠脊髓损伤后的表达变化

目的:探讨突触后密度蛋白95(PSD-95)在脊髓损伤(SCI)后的表达变化以及定位情况。方法:使用改良Allen's法建立大鼠急性脊髓损伤模型。采用实时定量PCR和Western印迹法测定损伤后各时间段PSD-95 mRNA及其蛋白水平在脊髓中的表达变化。采用免疫荧光双标方法显示PSD-95在正常脊髓中的分布以及损伤后的定位改变。结果:PSD-95 mRNA及其蛋白水平在SCI后呈现逐渐下降的趋势,mRNA在5 d降到最低水平,蛋白水平在7 d最低。PSD-95与神经型一氧化氮合酶(nNOS)在SCI后8 h存在着共定位关系,但在SCI后7d,PSD-95除与nNOS部分共定位之外,还高表达于损伤局部活化中性粒细胞和巨噬细胞。结论:SCI后PSD-95在基因和蛋白水平呈现明显的时相变化,并且损伤后高表达在活化的炎症细胞,提示PSD-95参与了脊髓继发性损伤过程。     

17-β雌二醇提高巯醇抗氧化物（酶）治疗脊髓损伤的作用 

目的 探讨17-β雌二醇治疗脊髓损伤的分子机制,为临床应用雌激素治疗脊髓损伤提供理论依据。 方法 成年雄性SD大鼠180只,采用改良的Allen法构建大鼠急性脊髓挫伤模型后经17-β雌二醇治疗,采用化学比色法测定脊髓组织中丙二醛（MDA）和内源性巯醇抗氧化物（酶）：还原型谷胱甘肽（GSH）、超氧化物歧化酶（SOD）和谷胱甘肽过氧化物酶（GSH-Px）含量;免疫组织化学分析凋亡相关因子Caspase-3、Bcl2和Bax蛋白的表达变化。 结果 17-β雌二醇治疗组与脊髓损伤组比较,BBB评分明显增加;在多个时间点MDA含量明显降低;巯醇抗氧化物（酶）GSH、SOD和GSH-Px含量显著增加;Caspase-3和Bax表达的阳性细胞数明显减少;Bcl2表达的阳性细胞数明显增加（P<0.05）。 结论 大剂量的17-β雌二醇治疗可能通过调控内源性巯醇抗氧化物（酶）,提高肢体运动功能,抑制细胞凋亡,从而减轻脊髓损伤程度。     

活性氧在脊髓损伤中的作用及损伤机制

目的研究脊髓损伤(SCI)后脊髓组织中丙二醛(MDA)的动态水平变化和神经细胞凋亡及其凋亡相关因子表达的变化,探讨活性氧(ROS)在SCI后的作用及其分子机制。方法成年雄性大鼠132只,用改良的Allen法复制大鼠急性SCI模型,致大鼠脊髓(T10)中度挫伤,采用化学比色法测定不同时间段受损脊髓组织的MDA含量;免疫组织化学法分析受损脊髓组织区域凋亡相关因子Caspase-3、Bcl-2和Bax的表达变化;荧光原位缺口末端标记法(TUNEL)检测细胞凋亡。结果SCI后6h,脊髓组织中MDA含量明显增高并维持到损伤后5d,期间在6h和3d出现两次高峰,7d基本恢复正常;SCI后6h脊髓组织中凋亡细胞开始增多,3d达高峰,以后逐渐减少,各时间点与假手术组比较有显著性的差异;Bcl-2和Bax蛋白损伤后6h开始有较多的表达,以后快速增多,5d达高峰,然后逐渐回落。Caspase-3蛋白在损伤后6h开始增多,3d达高峰,以后逐渐减少。3种凋亡相关因子在各时间点与假手术组比较有显著性差异;甲基强的松龙(MPSS)治疗组与SCI组比较:MDA含量、凋亡细胞数、凋亡因子Caspase-3和Bax表达减少,Bcl-2表达增加,并且在部分时间点有显著性差异。结论在SCI后ROS可能通过促进Caspase-3表达和降低Bcl-2/Bax之间的比值诱导神经细胞凋亡,从而加重了SCI继发性损伤。