Function of microglia and macrophages in secondary damage after spinal cord injury

Spinal cord injury （SCI） is a devastating type of neurological trauma with limited therapeutic op- portunities. The pathophysiology of SCI involves primary and secondary mechanisms of injury. Among all the secondary injury mechanisms, the inflammatory response is the major contrib- utor and results in expansion of the lesion and further loss of neurologic function. Meanwhile, the inflammation directly and indirectly dominates the outcomes of SCI, including not only pain and motor dysfunction, but also preventingneuronal regeneration. Microglia and macrophages play very important roles in secondary injury. Microglia reside in spinal parenchyma and survey the microenvironment through the signals of injury or infection. Macrophages are derived from monocytes recruited to injured sites from the peripheral circulation. Activated resident microglia and monocyte-derived macrophages induce and magnify immune and inflammatory responses not only by means of their secretory moleculesand phagocytosis, but also through their influence on astrocytes, oligodendrocytes and demyelination. In this review, we focus on the roles of mi- croglia and macrophages in secondary injury and how they contribute to the sequelae of SCI.

Effects of low dose Glibenclamide on secondary damage after acute spinal cord injury in rats

Objective To investigate the effects of Glibenclamide on reduction of secondary damage after acute spinal cord injury in rats.Methods Ninety rats were randomly divided into control group(laminectomy alone),spinal cord injury group(injury group),and treatment group(treated

Secondary damage in trauma and limited access dressing: a review

Secondary damage in trauma may increase morbidity,mortality and the cost of treatment considerably.This article reviews the literature of 46 relevant articles on this topic.We hope to provide a better understanding of the various mechanisms that can lead to secondary damage following major trauma and aim to improve the management of such in trauma patients.We also explore the utility of limited access dressing and its ability to minimize and treat secondary musculoskeletal trauma.Four interdependent cellular mechanisms have been described that contribute and perpetuate secondary tissue damage-lysosomal,protein/enzyme denaturation,membrane permeability and mitochondrial.Systemic changes are mainly due to systemic hypoxia and the systemic inflammatory response syndrome.Limited access dressing appears to be an efficient and cost-effective method for the management of secondary damage,as evidenced by the reduced number of debridements,shorter wound coverage time,and reduction in total length of hospital stay while lowering treatment costs and improving quality of care.

Preventive and therapeutic effect of simvastatin on secondary inflammatory damage of rats with cerebral hemorrhage

Objective:To investigate the preventive and therapeutic effect and mechanism of simvastatin on secondary inflammatory damage of rats with cerebral hemorrhage.Methods:Sixty SD rat aged 9-12 weeks were chosen and divided into the control group,model group and simvastatintreated group randomly with 20 rats in each group.Rats in the model group and simvastatintreated group were infused with autologous fresh uncoagulated blood to the right brain tissue of the basal ganglia to build the cerebral hemorrhage model,while rats in the control group were treated with the same amount of normal saline.Then,rats in the simvastatin-treated group were given a gavage of 3 mg/kg of simvastatin once a day after modeling.Rats in the three groups were given nerve dysfunction score(NDS) and wet-dry weighting method was used to detect the brain water content(BWC) of brain tissues around the lesion of the rats.Then Nissl staining was conducted and the undamaged neurons were counted.Immunohistochemical SP method was applied to count the number of NF-d the immuno fluorκB,TLR4 and IL-1escence method wasβ positive cells in brain tissues around the lesions,an employed to determine the expression levels of NF-κB,TLR4 and IL-1me points were aβ proteins.Results:The NDS results of the simvastatin-treated group at all till significantly higher than those of the model group(P < 0.05);the BWC values of the simvastatin-treated group at all time points were all significantly lower than those of the model group at the same periods(P < 0.05);the number of the undamaged neurons around the lesions of the simvastatin-treated group at all time points were all significantly higher than those of the model group(P < 0.05);seven days after treatment,the number of the NF-κB,TLR4 and IL-1β positive cells in brain tissues around the lesions of the simvastatin-treated group were all significantly lower than those of the model group(P < 0.05),and its expression levels of NF-ower than those of the model group(κB,TLR4 and IL-1P < 0.05).Conclusioβ protein were also significantly lns:Simvastatin can inhibit the expressions of NF-κB,TLR4 and IL-1β proteins in rats with cerebral hemorrhage,and protect neurons and reduce secondary inflammatory damages by down-regulating the above protein-mediated inflammatory responses.

Perihematoma Damage at Different Time Points in Experimental Intracerebral Hemorrhage

The damage degree of neurons in perilesion at different time points was observed in order to explore the optimal operation occasion. Piglet lobar hematomas were produced by pressure-controlled infusions of 2.5 mL autonomous blood into the right frontal hemispheric white matter over 15 min, and the metabolic changes were ambulatorily detected with MRS at 3rd, 12th, 24th and 48th h after hematoma induction. Brain tissues of perihematoma were also obtained at different time points. The transcription level of Bax gene was detected by in situ hybridization and apoptosis by TUNEL technique, and the pathologic change of neurons was observed under an electron microscope. The results showed that the number of Bax positive cells reached the peak at 24 h （79.00± 4.243/5 fields）. There was no significant difference in A values between 3 h and 6 h, 12 h （P〉 0. 05）, but there significant difference between 24 h and 3 h, 6 h, 12 h （P〈0. 05）. The number of apoptotic cells reached the peak at 24 h （P〈0. 001）, and there was no significant difference between 3 h and 6 h （P=0. 999）. The area of the apoptotic cells showed no significant difference between 3 h and 6 h or among 3 h, 6 h and 6 h （P〉0.05）. Lac peak mainly occurred at 24 h and 48 h, while on the healthy side, no Lac peak was detectable. The ratio of NAA/Cr presented a descent tendency, but there was no significant difference among the groups before 12 h （P〉0. 05）, there was very significant difference between 3, 6 and 24, 48 h （P〈0. 01）. Under electronic microscopy, the neuronal damage surrounding hematoma in 3 to 6 h was milder than in 24 h to 48 h. It was concluded that the secondary apoptosis, damage and metabolic disturbance of the neurons surround- ing hematoma was milder in 3-6 h in acute intracerebral hemorrhage, while obviously aggravated in 24-48 h. An effective intervention is needed to reduce secondary damage as soon as possible.

Expression of long non-coding RNAs in complete transection spinal cord injury: a transcriptomic analysis

Long non-coding RNAs(lncRNAs)are abundantly expressed in the central nervous system and exert a critical role in gene regulation via multiple biological processes.To uncover the functional significance and molecular mechanisms of lncRNAs in spinal cord injury(SCI),the expression signatures of lncRNAs were profiled using RNA sequencing(RNA-seq)technology in a Sprague-Dawley rat model of the 10th thoracic vertebra complete transection SCI.Results showed that 116 of 14,802 detected lncRNAs were differentially expressed,among which 16—including eight up-regulated(H19,Vof16,Hmox2-ps1,LOC100910973,Ybx1-ps3,Nnat,Gcgr,LOC680254)and eight down-regulated(Rmrp,Terc,Ngrn,Ppp2r2b,Cox6a2,Rpl37a-ps1,LOC360231,Rpph1)—demonstrated fold changes>2 in response to transection SCI.A subset of these RNA-seq results was validated by quantitative real-time PCR.The levels of 821 mRNAs were also significantly altered post-SCI;592 mRNAs were up-regulated and 229 mRNAs were down-regulated by more than 2-fold.Gene Ontology(GO)and Kyoto Encyclopedia of Genes and Genomes(KEGG)analyses showed that differentially expressed mRNAs were related to GO biological processes and molecular functions such as injury and inflammation response,wound repair,and apoptosis,and were significantly enriched in 15 KEGG pathways,including cell phagocytosis,tumor necrosis factor alpha pathway,and leukocyte migration.Our results reveal the expression profiles of lncRNAs and mRNAs in the rat spinal cord of a complete transection model,and these differentially expressed lncRNAs and mRNAs represent potential novel targets for SCI treatment.We suggest that lncRNAs may play an important role in the early immuno-inflammatory response after spinal cord injury.This study was approved by the Administration Committee of Experimental Animals,Guangdong Province,China.

Melatonin for the treatment of spinal cord injury

Spinal cord injury（SCI） from trauma or disease severely impairs sensory and motor function. Neurorehabilitation after SCI is a complex medical process that focuses on improving neurologic function and repairing damaged connections in the central nervous system. An increasing number of preclinical studies suggest that melatonin may be useful for the treatment of SCI. Melatonin is an indolamine that is primarily secreted by the pineal gland and known to be regulated by photoperiodicity. However, it is also a versatile hormone with antioxidative, antiapoptotic, neuroprotective, and anti-inflammatory properties. Here, we review the neuroprotective properties of melatonin and the potential mechanisms by which it might be beneficial in the treatment of SCI. We also describe therapies that combine melatonin with exercise, oxytetracycline, and dexamethasone to attenuate the secondary injury after SCI and limit potential side effects. Finally, we discuss how injury at different spinal levels may differentially affect the secretion of melatonin.