Bosentan reduces neuronal apoptosis following spinal cord ischemic reperfusion injury

Multiple Sclerosis: Inflammatory and Neuroglial Aspects

Multiple sclerosis (MS) represents the most common acquired demyelinating disorder of the central nervous system (CNS). Its pathogenesis, in parallel with the well-established role of mechanisms pertaining to autoimmunity, involves several key functions of immune, glial and nerve cells. The disease's natural history is complex, heterogeneous and may evolve over a relapsing-remitting (RRMS) or progressive (PPMS/SPMS) course. Acute inflammation, driven by infiltration of peripheral cells in the CNS, is thought to be the most relevant process during the earliest phases and in RRMS, while disruption in glial and neural cells of pathways pertaining to energy metabolism, survival cascades, synaptic and ionic homeostasis are thought to be mostly relevant in long-standing disease, such as in progressive forms. In this complex scenario, many mechanisms originally thought to be distinctive of neurodegenerative disorders are being increasingly recognized as crucial from the beginning of the disease. The present review aims at highlighting mechanisms in common between MS, autoimmune diseases and biology of neurodegenerative disorders. In fact, there is an unmet need to explore new targets that might be involved as master regulators of autoimmunity, inflammation and survival of nerve cells.

Novel Therapeutic Effects in Rat Spinal Cord Injuries: Recovery of the Definitive and Early Spinal Cord Injury by the Administration of Pentadecapeptide BPC 157 Therapy

Recently, marked therapeutic effects pertaining to the recovery of injured rat spinal cords (1 min compression injury of the sacrocaudal spinal cord (S2-Co1) resulting in tail paralysis) appeared after a single intraperitoneal administration of the stable gastric pentadecapeptide BPC 157 at 10 min post-injury. Besides the demonstrated rapid and sustained recovery (1 year), we showed the particular points of the immediate effect of the BPC 157 therapy that began rapidly after its administration, (i) soon after injury (10 min), or (ii) later (4 days), in the rats with a definitive spinal cord injury. Specifically, in counteracting spinal cord hematoma and swelling, (i) in rats that had undergone acute spinal cord injury, followed by intraperitoneal BPC 157 application at 10 min, we focused on the first 10–30 min post-injury period (assessment of gross, microscopic, and gene expression changes). Taking day 4 post-injury as the definitive injury, (ii) we focused on the immediate effects after the BPC 157 intragastric application over 20 min of the post-therapy period. Comparable long-time recovery was noted in treated rats which had definitive tail paralysis: (iii) the therapy was continuously given per orally in drinking water, beginning at day 4 after injury and lasting one month after injury. BPC 157 rats presented only discrete edema and minimal hemorrhage and increased Nos1, Nos2, and Nos3 values (30 min post-injury, (i)) or only mild hemorrhage, and only discrete vacuolation of tissue (day 4, (ii)). In the day 4–30 post-injury study (iii), BPC 157 rats rapidly presented tail function recovery, and no demyelination process (Luxol fast blue staining).

Atorvastatin activates autophagy and promotes neurological function recovery after spinal cord injury

Atorvastatin, a lipid-lowering medication, provides neuroprotective effects, although the precise mechanisms of action remain unclear. Our previous studies confirmed activated autophagy following spinal cord injury, which was conducive to recovery of neurological functions. We hypothesized that atorvastatin could also activate autophagy after spinal cord injury, and subsequently improve recovery of neurological functions. A rat model of spinal cord injury was established based on the Allen method. Atorvastatin (5 mg/kg) was intraperitoneally injected at 1 and 2 days after spinal cord injury. At 7 days post-injury, western blot assay, reverse transcription-polymerase chain reaction, and terminal deoxynucleotidyl transferase-mediated dUTP nick-end labeling (TUNEL) staining results showed increased Beclin-1 and light chain 3B gene and protein expressions in the spinal cord injury + atorvastatin group. Additionally, caspase-9 and caspase-3 expression was decreased, and the number of TUNEL-positive cells was reduced. Compared with the spinal cord injury + saline group, Basso, Beattie, and Bresnahan locomotor rating scale scores significantly increased in the spinal cord injury + atorvastatin group at 14-42 days post-injury. These findings suggest that atorvastatin activated autophagy after spinal cord injury, inhibited apoptosis, and promoted recovery of neurological function.

Endothelin-1 Immunoreactivity and its Association with Intramedullary Hemorrhage and Myelomalacia in Naturally Occurring Disk Extrusion in Dogs

Background

The pathophysiology of ascending/descending myelomalacia (ADMM) after canine intervertebral disk (IVD) extrusion remains poorly understood. Vasoactive molecules might contribute.

Hypothesis/Objectives

To investigate the immunoreactivity of endothelin‐1 (ET‐1) in the uninjured and injured spinal cord of dogs and its potential association with intramedullary hemorrhage and extension of myelomalacia.

Animals

Eleven normal control and 34 dogs with thoracolumbar IVD extrusion.

Methods

Spinal cord tissue of dogs retrospectively selected from our histopathologic database was examined histologically at the level of the extrusion (center) and in segments remote from the center. Endothelin‐1 immunoreactivity was examined immunohistochemically and by in situ hybridization. Associations between the immunoreactivity for ET‐1 and the severity of intramedullary hemorrhage or the extension of myelomalacia were examined.

Results

Endothelin‐1 was expressed by astrocytes, macrophages, and neurons and only rarely by endothelial cells in all dogs. At the center, ET‐1 immunoreactivity was significantly higher in astrocytes (median score 4.02) and lower in neurons (3.21) than in control dogs (3.0 and 4.54) (P < .001; P = .004) irrespective of the grade of hemorrhage or myelomalacia. In both astrocytes and neurons, there was a higher ET‐1 immunoreactivity in spinal cord regions remote from the center (4.58 and 4.15) than in the center itself (P = .013; P = .001). ET‐1 mRNA was present in nearly all neurons with variable intensity, but not in astrocytes.

Conclusion and Clinical Importance

Enhanced ET‐1 immunoreactivity over multiple spinal cord segments after IVD extrusion might play a role in the pathogenesis of ADMM. More effective quantitative techniques are required.

Targeting the blood-spinal cord barrier: A therapeutic approach to spinal cord protection against ischemia-reperfusion injury

One of the principal functions of physical barriers between the blood and central nervous system protects system (i.e., blood brain barrier and blood-spinal cord barrier) is the protection from toxic and pathogenic agents in the blood. Disruption of blood-spinal cord barrier (BSCB) plays a key role in spinal cord ischemia-reperfusion injury (SCIRI). Following SCIRI, the permeability of the BSCB increases. Maintaining the integrity of the BSCB alleviates the spinal cord injury after spinal cord ischemia. This review summarizes current knowledge of the structure and function of the BSCB and its changes following SCIRI, as well as the prevention and cure of SCIRI and the role of the BSCB.

Salvianolic acid A attenuates vascular remodeling in a pulmonary arterial hypertension rat model

AIM

The current therapeutic approaches have a limited effect on the dysregulated pulmonary vascular remodeling, which is characteristic of pulmonary arterial hypertension (PAH). In this study we examined whether salvianolic acid A (SAA) extracted from the traditional Chinese medicine 'Dan Shen' attenuated vascular remodeling in a PAH rat model, and elucidated the underlying mechanisms.

METHODS

PAH was induced in rats by injecting a single dose of monocrotaline (MCT 60 mg/kg, sc). The rats were orally treated with either SAA (0.3, 1, 3 mg·kg(-1)·d(-1)) or a positive control bosentan (30 mg·kg(-1)·d(-1)) for 4 weeks. Echocardiography and hemodynamic measurements were performed on d 28. Then the hearts and lungs were harvested, the organ indices and pulmonary artery wall thickness were calculated, and biochemical and histochemical analysis were conducted. The levels of apoptotic and signaling proteins in the lungs were measured using immunoblotting.

RESULTS

Treatment with SAA or bosentan effectively ameliorated MCT-induced pulmonary artery remodeling, pulmonary hemodynamic abnormalities and the subsequent increases of right ventricular systolic pressure (RVSP). Furthermore, the treatments significantly attenuated MCT-induced hypertrophic damage of myocardium, parenchymal injury and collagen deposition in the lungs. Moreover, the treatments attenuated MCT-induced apoptosis and fibrosis in the lungs. The treatments partially restored MCT-induced reductions of bone morphogenetic protein type II receptor (BMPRII) and phosphorylated Smad1/5 in the lungs.

CONCLUSION

SAA ameliorates the pulmonary arterial remodeling in MCT-induced PAH rats most likely via activating the BMPRII-Smad pathway and inhibiting apoptosis. Thus, SAA may have therapeutic potential for the patients at high risk of PAH.

Characteristics of mRNA dynamic expression related to spinal cord ischemia/reperfusion injury: a transcriptomics study

Following spinal cord ischemia/reperfusion injury, an endogenous damage system is immediately activated and participates in a cascade reaction. It is difficult to interpret dynamic changes in these pathways, but the examination of the transcriptome may provide some information. The transcriptome reflects highly dynamic genomic and genetic information and can be seen as a precursor for the proteome. We used DNA microarrays to measure the expression levels of dynamic evolution-related mRNA after spinal cord ischemia/reperfusion injury in rats. The abdominal aorta was blocked with a vascular clamp for 90 minutes and underwent reperfusion for 24 and 48 hours. The simple ischemia group and sham group served as controls. After rats had regained consciousness, hindlimbs showed varying degrees of functional impairment, and gradually improved with prolonged reperfusion in spinal cord ischemia/reperfusion injury groups. Hematoxylin-eosin staining demonstrated that neuronal injury and tissue edema were most severe in the 24-hour reperfusion group, and mitigated in the 48-hour reperfusion group. There were 8,242 differentially expressed mRNAs obtained by Multi-Class Dif in the simple ischemia group, 24-hour and 48-hour reperfusion groups. Sixteen mRNA dynamic expression patterns were obtained by Serial Test Cluster. Of them, five patterns were significant. In the No. 28 pattern, all differential genes were detected in the 24-hour reperfusion group, and their expressions showed a trend in up-regulation. No. 11 pattern showed a decreasing trend in mRNA whereas No. 40 pattern showed an increasing trend in mRNA from ischemia to 48 hours of reperfusion, and peaked at 48 hours. In the No. 25 and No. 27 patterns, differential expression appeared only in the 24-hour and 48-hour reperfusion groups. Among the five mRNA dynamic expression patterns, No. 11 and No. 40 patterns could distinguish normal spinal cord from pathological tissue. No. 25 and No. 27 patterns could distinguish simple ischemia from ischemia/reperfusion. No. 28 pattern could analyze the need for inducing reperfusion injury. The study of specific pathways and functions for different dynamic patterns can provide a theoretical basis for clinical differential diagnosis and treatment of spinal cord ischemia/reperfusion injury.

Preventive Role of Endothelin Antagonist on Kidney Ischemia: Reperfusion Injury in Male and Female Rats

Background:

Renal ischemia/reperfusion injury (RIRI) is the most common cause of acute kidney injury. We tested the protective role of endothelin-1 receptor blocker; bosentan (BOS) in animal model of RIRI in two different genders.

Methods:

Male and female Wistar rats were assigned as sham operated (sham), control group (ischemia), and case group (ischemia + BOS) treated with BOS (50 mg/kg) 2 h before bilateral kidney ischemia induced by clamping renal vessels for 45 min followed by 24 h of renal reperfusion.

Results:

The RIRI significantly increased the serum levels of blood urea nitrogen and creatinine in both genders (P < 0.05). These values were significantly decreased by BOS in both genders. In male rats, the serum levels of malondialdehyde in the ischemia + BOS group were decreased significantly when compared with ischemia group (P < 0.05).

Conclusions:

BOS can be used in both genders to attenuate kidney ischemia injury possibly due to its effect in the renal vascular system.

Expression of C5a and its receptor following spinal cord ischemia reperfusion injury in the rat

STUDY DESIGN

Experimental study.

OBJECTIVE

To investigate the expression of C5a and its receptor after spinal cord ischemia reperfusion injury (SIRI) in rat.

SETTING

Department of Neurosurgery, the Second Affiliated Hospital, Xi'an Jiaotong University, Shaanxi Province, Xi'an, China

METHODS

Sprague Dawley rats were subjected to 1 h of infrarenal aorta occlusion to induce spinal cord ischemia. Spinal cord was reperfused for 12, 24, 48 h or 3 days separately after ischemia, respectively. Enzyme-linked immunosorbent assay was used to detect C5a in rat serum. Immunofluorescent staining was performed to detect the expression and cellular localization of C5aR in spinal cord following SIRI.

RESULTS

Following SIRI, the motor behavior of the rats was significantly compromised. The serum concentration of C5a in the rat was elevated after SIRI and peaked at 24 h. C5aR was significantly upregulated in the lumbar spinal cord following SIRI and expressed on motor neurons and the microglia, but not astrocyte. There was no significant difference in the expression level of C5aR localized on motor neurons after SIRI. Remarkable upregulation of the C5aR may be associated with increased number of C5aR-positive microglia and elevated cellular expression level.

CONCLUSION

This study provides the first evidence of the expression of C5a and its receptors in SIRI and suggests their possible contribution to SIRI in a rat model.

Bosentan protects the spinal cord from ischemia reperfusion injury in rats through vascular endothelial growth factor receptors

STUDY DESIGN

Experimental study.

OBJECTIVES

To investigate whether Bosentan, an endothelin-A/-B dual receptor antagonist, could protect neurons after spinal cord ischemia reperfusion (SCIR) injury in rats and its underlying signaling pathway.

SETTING

Department of Neurosurgery, the Second Affiliated Hospital, Xi'an Jiaotong University School of Medicine, Xi'an, Shaanxi Province, China.

METHODS

Sprague-Dawley rats were randomly divided into two groups, saline group (IRS, n=48) and Bosentan group (IRB, 5 mg kg(-1), n=48). After ischemia for 1 h with occlusion of the infrarenal aorta, spinal cord were reperfused for 6h, 12h, 24h, 3d, 5d, and 7d separately. Enzyme-linked immunosorbent assay was used to detect vascular endothelial growth factor (VEGF) in serum. Immunohistochemistry was performed to detect protein expression of VEGF, VEGF receptor 1 (FLT-1) and VEGF receptor 2 (FLK-1). Gene expressions of VEGF and its receptors were evaluated using the quantitative reverse transcription polymerase chain reaction.

RESULTS

Compared with the IRS group, gene and protein expressions of VEGF, FLT-1 and FLK-1 were significantly increased (P<0.05), so was the concentration of VEGF in plasma (P<0.05). FLK-1 was expressed on spinal cord neurons.