Glycyrrhizin protects spinal cord and reduces inflammation in spinal cord ischemia-reperfusion injury

Glycyrrhizic acid alleviated MI/R-induced injuries by inhibiting Hippo/YAP signaling pathways

BACKGROUND

Previous research has demonstrated that glycyrrhizic acid (GA) exhibits antioxidant, anti-inflammatory, and antiapoptotic characteristics. Using myocardial ischemia/reperfusion injury as a case study, this study aims to clarify the functional significance of GA and to elucidate the mechanisms involved.

MATERIALS AND METHODS

In this study, an MI/R injury model was established both in vivo and in vitro to investigate the impact of GA on MI/R injury. The viability of H9c2 cells was evaluated using the Cell Counting Kit-8. Myocardial damage was assessed through the measurement of creatine kinase myocardial band (CK-MB) levels and lactate dehydrogenase (LDH), HE staining, and MASSON staining. Inflammatory cytokine levels (IL-6, IL-1β, IL-10, and TNF-α) were measured to determine the presence of inflammation. Cellular oxidative stress was evaluated by measuring ROS and MMP levels, while cardiac function was assessed using cardiac color Doppler ultrasound. Immunofluorescence staining to determine the nuclear translocation of YAP, TUNEL to determine apoptosis, and western blotting to determine gene expression.

RESULTS

GA treatment effectively alleviated myocardial injury induced by MI/R, as evidenced by reduced levels of inflammatory cytokines (IL-1β, IL-6, IL-10, and TNF-α) and cardiac biomarkers (CK-MB, LDH) in MI/R rats. Moreover, There was a significant increase in cell viability in vitro after GA treatment and inhibited reactive oxygen species (ROS) during oxidative stress, while also increasing mitochondrial membrane potential (MMP) in vitro. The Western blot findings indicate that GA treatment effectively suppressed apoptosis in both in vivo and in vitro settings. Additionally, GA demonstrated inhibitory effects on the activation of the Hippo/YAP signaling pathway triggered by MI/R and facilitated YAP nuclear translocation both in vitro and in vivo. It has been found, however, in vitro, that silencing the YAP gene negates GA's protective effect against hypoxia/reoxygenation-induced myocardial injury.

CONCLUSION

This study suggests that GA regulates YAP nuclear translocation by inhibiting the Hippo/YAP signaling pathway, which protects ists against MI/R injury. This finding may present a novel therapeutic approach for the treatment of MI/R.

Clinical significance of miR-142-5p in spinal cord injury caused by spinal trauma and its functional role in the regulation of inflammation

OBJECTIVE

Spinal cord injury (SCI) is a severe traumatic disease in the central nervous system, and can result in neuronal injury. Altered miRNA expression is identified to be involved in the pathogenesis of SCI.

DESIGN

This study investigated the clinical value of miR-142-5p in SCI patients, and explored its functional role in the regulation of inflammatory.

SETTING

The First Affiliated Hospital of Soochow University.

PARTICIPANTS

Ninety-eight patients with acute spinal trauma.

INTERVENTIONS

All patients were recruited, and divided into complete SCI group, incomplete SCI group and normal nerve function group.

OUTCOME MEASURES

Real-time quantitative PCR (qRT-PCR) was used to detect the expression levels of miR-142-5p. CCK-8 and flow cytometry assay were performed to evaluate the cell viability and apoptosis. ELISA assay was applied to estimate the levels of interleukin-6 (IL-6) and tumor necrosis factor-α (TNF-α).

RESULTS

Serum miR-142-5p level was significantly increased in SCI patients, especially the complete SCI cases. ROC curve analysis suggested miR-142-5p could distinguish SCI patients from normal nerve function patients and was associated with the severity of SCI. A positive association was detected between miR-142-5p and serum levels of IL-6, TNF-α in SCI patients. Downregulation of miR-142-5p significantly reduced the protein levels of both IL-6 and TNF-α in LPS treated PC12 cells, and weakened LPS induced cell apoptosis.

CONCLUSION

MiR-142-5p is a potential biomarker for the occurrence of SCI in acute spinal trauma patients. Downregulation of miR-142-5p plays an anti-inflammatory effect for SCI patients.

Effect of Diammonium Glycyrrhizinate in Improving Focal Cerebral Ischemia-Reperfusion Injury in Rats Through Multiple Mechanisms

OBJECTIVE

Acute ischemic stroke is a current major disabling and killer disease worldwide. We aimed to investigate the protective effect and mechanism of diammonium glycyrrhizinate in alleviating acute ischemic stroke.

METHODS

Ninety male Sprague Dawley (SD) rats (weighing 250-300 g) were randomly allocated into three groups: sham operation group (sham group), diammonium glycyrrhizinate group (DG group) and model group (model group) each with 30 individuals. A rat model of focal CIR injury was established by reversible middle cerebral artery occlusion.

RESULTS

Zea-Longa scores for the rats in the DG group and model group were 7-fold and 8-fold higher than those of the sham group 2 h post-surgery (2.90 ± 0.99 vs. 0.30 ± 0.53, P < .05; 2.80 ± 0.61 vs. 0.30 ± 0.53, P < .05, respectively). Three days after model establishment, the scores of DG group were 26.92% lower compared with those of the model group (1.90 ± 0.76 vs. 2.60 ± 0.62, P < .05). In addition, compared with the sham group, the number of Nissl bodies and Akt-positive cells in were 27.35% and 30.42% lower in the hippocampus of the DG group (Nissl bodies: 83.40 ± 7.01 vs. 115.60 ± 11.97, p < 0.05; Akt-positive cells: 94.70 ± 8.23 vs. 136.10 ± 10.37, P < .05) and 58.65% and 57.31% lower in the model group (Nissl bodies: 47.80 ± 4.91 vs. 115.60 ± 11.97, P < .05; Akt-positive cells: 58.10 ± 4.98 vs. 136.10 ± 10.37, P < 0.05), respectively. However, the number of Nissl bodies and Akt-positive cells in the hippocampus of DG group were 74.48% and 62.9% higher compared with the model group, respectively (Nissl bodies: 83.40 ± 7.01 vs. 47.80 ± 4, P < 0.05; Akt-positive cells: 94.70 ± 8.23 vs. 58.10 ± 4.98, P < .05). In addition, compared with the sham group, the number of caspase-3-positive cells, the expression level of p38 mitogen-activated protein kinase (MAPK) and the expression of matrix metallopeptidase 9 (MMP-9) were 2-fold, 34.38%, 64.78% higher in the DG group (caspase-3-positive cells: 78.70 ± 6.52 vs. 27.10 ±3.00, P < .05; p-38MAPK: 0.43 ± 0.15 vs. 0.32 ± 0.10, P < .05; MMP-9: 14.83 ± 1.18 vs. 9.00 ± 2.05, P < .05, respectively), and more than 3-fold, 1-fold and 1-fold higher in model group (caspase-3-positive cells: 121.10 ± 11.04 vs. 27.10 ± 3.00, P < .05; p-38MAPK: 0.70 ± 0.12 vs. 0.32 ± 0.10, P < .05; MMP-9: 19.00 ± 1.90 vs. 9.00 ± 2.05, P < .05), respectively. However, the number of caspase-3-positive cells and the expression levels of p-38MAPK and MMP-9 were 35.01%, 38.57% and 28.12% lower in DG group compared with the model group (caspase-3-positive cells: 78.70 ± 6.52 vs. 121.10 ± 11.04, P < .05; p-38MAPK: 0.43 ± 0.15 vs. 0.70 ± 0.12, P < .05; MMP-9: 14.83 ± 1.18 vs. 19.00 ± 1.90, P < .05).

CONCLUSIONS

Our study showed that diammonium glycyrrhizinate at 20 mg/kg/day had a protective effect on cerebral ischemia-reperfusion injury in rats by promoting formation of Nissl bodies and increasing protein expression of Akt while decreasing that of caspase-3, p38 MAPK and MMP-9, either directly or indirectly, by inhibiting apoptosis and reducing neuroinflammation. All these mechanisms resulted in improved overall neurological function.

Astragalin Protects against Spinal Cord Ischemia Reperfusion Injury through Attenuating Oxidative Stress-Induced Necroptosis

Spinal cord ischemia/reperfusion (SCI/R) injury is a devastating complication usually occurring after thoracoabdominal aortic surgery. However, it remains unsatisfactory for its intervention by using pharmacological strategies. Oxidative stress is a main pharmacological process involved in SCI/R, which will elicit downstream programmed cell death such as the novel defined necroptosis. Astragalin is a bioactive natural flavonoid with a wide spectrum of pharmacological activities. Herein, we firstly evaluated the effect of astragalin to oxidative stress as well as the possible downstream necroptosis after SCI/R in mice. Our results demonstrated that astragalin improves the ethological score and histopathological deterioration of SCI/R mice. Astragalin mitigates oxidative stress and ameliorates inflammation after SCI/R. Astragalin blocks necroptosis induced by SCI/R. That is, the amelioration of astragalin to the motoneuron injury and histopathological changes. Indicators of oxidative stress, inflammation, and necroptosis after SCI/R were significantly blocked. Summarily, we firstly illustrated the protection of astragalin against SCI/R through its blockage to the necroptosis at downstream of oxidative stress.

Histological Findings After Aortic Cross-Clamping in Preclinical Animal Models

Spinal cord ischemic injury and paralysis are devastating complications after open surgical repair of thoracoabdominal aortic aneurysms. Preclinical models have been developed to simulate the clinical paradigm to better understand the neuropathophysiology and develop therapeutic treatment. Neuropathological findings in the preclinical models have not been comprehensively examined before. This systematic review studies the past 40 years of the histological findings after open surgical repair in preclinical models. Our main finding is that damage is predominantly in the grey matter of the spinal cord, although white matter damage in the spinal cord is also reported. Future research needs to examine the neuropathological findings in preclinical models after endovascular repair, a newer type of surgical repair used to treat aortic aneurysms.

Non-Coding RNAs: Emerging Therapeutic Targets in Spinal Cord Ischemia-Reperfusion Injury

Paralysis or paraplegia caused by transient or permanent spinal cord ischemia–reperfusion injury (SCIRI) remains one of the most devastating post-operative complications after thoracoabdominal aortic surgery, even though perioperative strategies and surgical techniques continue to improve. Uncovering the molecular and cellular pathophysiological processes in SCIRI has become a top priority. Recently, the expression, function, and mechanism of non-coding RNAs (ncRNAs) in various diseases have drawn wide attention. Non-coding RNAs contain a variety of biological functions but do not code for proteins. Previous studies have shown that ncRNAs play a critical role in SCIRI. However, the character of ncRNAs in attenuating SCIRI has not been systematically summarized. This review article will be the first time to assemble the knowledge of ncRNAs regulating apoptosis, inflammation, autophagy, and oxidative stress to attenuate SCIRI. A better understanding of the functional significance of ncRNAs following SCIRI could help us to identify novel therapeutic targets and develop potential therapeutic strategies. All the current research about the function of nRNAs in SCIRI will be summarized one by one in this review.

Argon Attenuates Multiorgan Failure in Relation with HMGB1 Inhibition

Argon inhalation attenuates multiorgan failure (MOF) after experimental ischemic injury. We hypothesized that this protection could involve decreased High Mobility Group Box 1 (HMGB1) systemic release. We investigated this issue in an animal model of MOF induced by aortic cross-clamping. Anesthetized rabbits were submitted to supra-coeliac aortic cross-clamping for 30 min, followed by 300 min of reperfusion. They were randomly divided into three groups (n = 7/group). The Control group inhaled nitrogen (70%) and oxygen (30%). The Argon group was exposed to a mixture of argon (70%) and oxygen (30%). The last group inhaled nitrogen/oxygen (70/30%) with an administration of the HMGB1 inhibitor glycyrrhizin (4 mg/kg i.v.) 5 min before aortic unclamping. At the end of follow-up, cardiac output was significantly higher in Argon and Glycyrrhizin vs. Control (60 ± 4 and 49 ± 4 vs. 33 ± 8 mL/kg/min, respectively). Metabolic acidosis was attenuated in Argon and Glycyrrhizin vs. Control, along with reduced amount of norepinephrine to reverse arterial hypotension. This was associated with reduced interleukin-6 and HMGB1 plasma concentration in Argon and Glycyrrhizin vs. Control. End-organ damages were also attenuated in the liver and kidney in Argon and Glycyrrhizin vs. Control, respectively. Argon inhalation reduced HMGB1 blood level after experimental aortic cross-clamping and provided similar benefits to direct HMGB1 inhibition.

High Mobility Group Box-1 and Blood-Brain Barrier Disruption

Increasing evidence suggests that inflammatory responses are involved in the progression of brain injuries induced by a diverse range of insults, including ischemia, hemorrhage, trauma, epilepsy, and degenerative diseases. During the processes of inflammation, disruption of the blood–brain barrier (BBB) may play a critical role in the enhancement of inflammatory responses and may initiate brain damage because the BBB constitutes an interface between the brain parenchyma and the bloodstream containing blood cells and plasma. The BBB has a distinct structure compared with those in peripheral tissues: it is composed of vascular endothelial cells with tight junctions, numerous pericytes surrounding endothelial cells, astrocytic endfeet, and a basement membrane structure. Under physiological conditions, the BBB should function as an important element in the neurovascular unit (NVU). High mobility group box-1 (HMGB1), a nonhistone nuclear protein, is ubiquitously expressed in almost all kinds of cells. HMGB1 plays important roles in the maintenance of chromatin structure, the regulation of transcription activity, and DNA repair in nuclei. On the other hand, HMGB1 is considered to be a representative damage-associated molecular pattern (DAMP) because it is translocated and released extracellularly from different types of brain cells, including neurons and glia, contributing to the pathophysiology of many diseases in the central nervous system (CNS). The regulation of HMGB1 release or the neutralization of extracellular HMGB1 produces beneficial effects on brain injuries induced by ischemia, hemorrhage, trauma, epilepsy, and Alzheimer’s amyloidpathy in animal models and is associated with improvement of the neurological symptoms. In the present review, we focus on the dynamics of HMGB1 translocation in different disease conditions in the CNS and discuss the functional roles of extracellular HMGB1 in BBB disruption and brain inflammation. There might be common as well as distinct inflammatory processes for each CNS disease. This review will provide novel insights toward an improved understanding of a common pathophysiological process of CNS diseases, namely, BBB disruption mediated by HMGB1. It is proposed that HMGB1 might be an excellent target for the treatment of CNS diseases with BBB disruption.

Changes in long non-coding RNA transcriptomic profiles after ischemia-reperfusion injury in rat spinal cord

With the aim of exploring expression profiles and biological functions of long non-coding RNA (lncRNA) and mRNAs after spinal cord ischemia-reperfusion injury (SCII), differentially expressed lncRNAs (DElncRNAs) and mRNAs (DEmRNAs) in rat spinal cords were identified following SCII through high-throughput RNA sequencing. In total, 1,455 lncRNAs and 6,707 mRNAs were observed to be differentially expressed (—Fold Change— ≥ 2 and P < 0.05) after SCII, including 761 up-regulated and 694 down-regulated lncRNAs, 3,772 up-regulated and 2,935 down-regulated mRNAs. Gene ontology and KEGG pathway analysis showed that the DElncRNAs and DEmRNAs were implicated in many different biological processes and pathways. Further, lncRNA-mRNA co-expression networks were built to explore the potential roles of these DElncRNAs. Our results demonstrate genome-wide lncRNA and mRNA expression patterns in spinal cords after SCII, which may play vital roles in post-SCII pathophysiological processes. These findings are important for future functional research on the lncRNAs involved in SCII and might be critical for providing new insight into identification of potential targets for SCII therapy.

Notoginsenoside R1 alleviates lipopolysaccharide-triggered PC-12 inflammatory damage via elevating microRNA-132

BACKGROUND

Delayed inflammatory response is closely associated with the severity of Spinal cord injury (SCI). Herein, the function and molecular mechanism of notoginsenoside R1 (NGR1) in the in vitro model of SCI inflammation injury were explored.

METHODS

PC-12 neuronal cells were subjected with LPS to construct a cell-based model of SCI inflammatory injury. NGR1 was applied in this cell model. miR-132 was silenced by transfection with miR-132 inhibitor. Cell viability and apoptosis were assessed, respectively. Then, the expression changes of pro-inflammatory cytokines and JNK pathway were examined.

RESULTS

In this model, LPS was neurotoxic, with inhibiting PC-12 cell viability, inducing apoptosis, and enhancing concentrations of IL-6, IL-8 and TNF-α. However, NGR1 weakened the influence of LPS on PC-12 cells via elevating cell viability, decreasing apoptosis, decreasing pro-inflammatory cytokines expression, and suppressing activation of JNK signalling pathway. miR-132 was up-regulated by NGR1 treatment. Silence of miR-132 eliminated the influence of NGR1 on LPS-stimulated PC-12 cells.

CONCLUSION

NGR1 relieved PC-12 cells from LPS-triggered inflammatory damage via elevating miR-132 and hereafter suppressing JNK pathway.

miR-34a alleviates spinal cord injury via TLR4 signaling by inhibiting HMGB-1

The aim of the present study was to investigate the effect of microRNA (miR)-34a on spinal cord injury (SCI)-induced inflammation and the possible underlying mechanisms. The results indicated that miR-34a expression was downregulated in a rat model of SCI compared with the control group. Furthermore, miR-34a knockdown was demonstrated to aggravate inflammation, inhibit cell proliferation and enhance apoptosis in an in vitro model of SCI. MiR-34a inhibition was demonstrated to upregulate the expression of inducible nitric oxide synthase and nitric oxide, as well as inducing the expression of toll-like receptor 4 (TLR4) and high mobility group box-1 (HMGB-1) in an in vitro model of SCI. TLR4 inhibitor reduced the effects of miR-34a downregulation on inflammation and cell growth in SCI. Together, these results suggest that miR-34a is able to alleviate SCI via inhibiting HMGB-1 expression in TLR4 signaling.

Glycyrrhizic acid ameliorates the kynurenine pathway in association with its antidepressant effect

Our previous study implied the role of central high mobility group box 1 (HMGB1) in lipopolysaccharide (LPS)-induced depressive-like behaviors that could partially abrogate by glycyrrhizic acid (GZA). Here, we considered the potential mechanism underlying GZA ameliorating chronic stress-induced depression both in vivo and in vitro. Depression model was established with the 4-week chronic unpredictable mild stress (CUMS) mice. Sucrose preference test, tail suspension test and open field test were performed to reflect depressive-like behaviors. Enzyme activity of indoleamine-2,3-dioxygenase (IDO) was recorded with the ratio of kynurenine (KYN) / tryptophan (Trp). Transcription of gene was evaluated by RT-PCR. Along with depressive-like behaviors, IDO, the rate-limiting enzyme of the kynurenine pathway (KP), was upregulated at the level of mRNA expression, and enzyme activity was also elevated in stressed hippocampi and LPS/HMGB1-treated hippocampus slices. Treatment of mice with GZA, the inhibitor of HMGB1, prevented the activated enzymes in KP and the development of depressive-like behaviors. These experiments demonstrate that GZA may restrain HMGB1 thus improving chronic stress-induced depressive behavior through regulating KP.

Protective effect of glycyrrhizin on myocardial ischemia/reperfusion injury-induced oxidative stress, inducible nitric oxide synthase and inflammatory reactions through high-mobility group box 1 and mitogen-activated protein kinase expression

Glycyrrhizin, which is a type of perennial leguminous caudex, has been used in various Asian countries, including P.R. China, India and Japan, for thousands of years. The present study was designed to investigate the protective effect of glycyrrhizin on myocardial ischemia/reperfusion (I/R) injury through oxidative stress, inducible nitric oxide synthase (iNOS), and inflammatory reactions via high-mobility group box 1 (HMGB1) and mitogen-activated protein kinase (MAPK) expression. Sprague-Dawley rats were divided into five groups: Sham; myocardial I/R injury + non-treated; myocardial I/R injury + 2 mg/kg glycyrrhizin; myocardial I/R injury + 4 mg/kg glycyrrhizin; and myocardial I/R injury + 10 mg/kg glycyrrhizin. Pre-treatment with glycyrrhizin significantly reduced infarct size and inhibited creatine kinase, creatine kinase-MB, lactate dehydrogenase and cardiac troponin T activities in rats with myocardial I/R injury. Furthermore, glycyrrhizin treatment significantly suppressed oxidative stress, iNOS protein expression and inflammatory reactions in rats with myocardial I/R injury. Additionally, treatment with glycyrrhizin significantly decreased the release of HMGB1 from the cerebral cortex into the serum in rats with myocardial I/R injury. Notably, glycyrrhizin significantly suppressed p-ERK, p-p38 MAPK and p-c-Jun N-terminal kinase protein expressions, and promoted extracellular signal-regulated kinase protein expression in rats with myocardial I/R injury. Collectively, the present study indicates that the protective effect of glycyrrhizin may reduce myocardial I/R injury through oxidative stress, iNOS and inflammatory reactions, via HMGB1 and MAPK expression.

Moderate hypothermia increased the incidence of delayed paralysis through activation of the spinal microglia in an aortic cross-clamping rat model

BACKGROUND

Hypothermia reduces immediate paralysis during surgical repair of aortic aneurysms. However, it is unknown what the impact of hypothermia is on delayed paralysis, a serious complication of this type of surgery.

METHODS

Sprague-Dawley rats were subjected to occlusion of the descending aorta at different duration under normothermia (38.0±0.5) or hypothermia (33.0±0.5°). Neurologic function was assessed. Motor neuron number, glial activation, and cytokine expression in the spinal cord were examined. Minocycline was administered perioperatively by intraperitoneal injection in the rats subjected to the aorta occlusion.

RESULTS

In contrast to normothermia conditions at which immediate paralysis occurred when the duration of aorta occlusion exceeded 11.5min, hypothermia did not induce immediate paralysis if the duration of aorta occlusion was less than 41min. However, delayed paralysis was developed when the duration of aorta occlusion exceeded 18min, and reached peak level when the duration of aorta occlusion was 40min at hypothermia condition. The number of motoneurons was significantly decreased (P<0.05) at 30h postoperation. In addition, microglia was activated, and interleukin-1β and interleukin-6 levels were upregulated, both of which were co-localized in microglia at 24h postoperation in the hypothermia group. Minocycline treatment attenuated the incidence and degree of paralysis but did not decrease the mortality.

CONCLUSIONS

Hypothermia, a neuroprotective strategy in cardiothoracic surgery, increased the incidence of delayed paralysis through activation of spinal microglia and cytokines. Blocking the activated microglia may be a potential intervention to prevent the incidence of delayed paralysis.

Anti-Inflammation of Natural Components from Medicinal Plants at Low Concentrations in Brain via Inhibiting Neutrophil Infiltration after Stroke

Inflammation after stroke consists of activation of microglia/astrocytes in situ and infiltration of blood-borne leukocytes, resulting in brain damage and neurological deficits. Mounting data demonstrated that most natural components from medicinal plants had anti-inflammatory effects after ischemic stroke through inhibiting activation of resident microglia/astrocytes within ischemic area. However, it is speculated that this classical activity cannot account for the anti-inflammatory function of these natural components in the cerebral parenchyma, where they are detected at very low concentrations due to their poor membrane permeability and slight leakage of BBB. Could these drugs exert anti-inflammatory effects peripherally without being delivered across the BBB? Factually, ameliorating blood-borne neutrophil recruitment in peripheral circulatory system has been proved to reduce ischemic damage and improve outcomes. Thus, it is concluded that if drugs could achieve effective concentrations in the cerebral parenchyma, they can function via crippling resident microglia/astrocytes activation and inhibiting neutrophil infiltration, whereas the latter will be dominating when these drugs localize in the brain at a low concentration. In this review, the availability of some natural components crossing the BBB in stroke will be discussed, and how these drugs lead to improvements in stroke through inhibition of neutrophil rolling, adhesion, and transmigration will be illustrated.

Glycyrrhizin Protects against Acetaminophen-Induced Acute Liver Injury via Alleviating Tumor Necrosis Factor α-Mediated Apoptosis

Acetaminophen (APAP) overdose is the leading cause of drug-induced acute liver failure in Western countries. Glycyrrhizin (GL), a potent hepatoprotective constituent extracted from the traditional Chinese medicine liquorice, has potential clinical use in treating APAP-induced liver failure. The present study determined the hepatoprotective effects and underlying mechanisms of action of GL and its active metabolite glycyrrhetinic acid (GA). Various administration routes and pharmacokinetics-pharmacodynamics analyses were used to differentiate the effects of GL and GA on APAP toxicity in mice. Mice deficient in cytochrome P450 2E1 enzyme (CYP2E1) or receptor interacting protein 3 (RIPK3) and their relative wild-type littermates were subjected to histologic and biochemical analyses to determine the potential mechanisms. Hepatocyte death mediated by tumor necrosis factorα(TNFα)/caspase was analyzed by use of human liver-derived LO2 cells. The pharmacokinetics-pharmacodynamics analysis using various administration routes revealed that GL but not GA potently attenuated APAP-induced liver injury. The protective effect of GL was found only with intraperitoneal and intravenous administration and not with gastric administration. CYP2E1-mediated metabolic activation and RIPK3-mediated necroptosis were unrelated to GL's protective effect. However, GL inhibited hepatocyte apoptosis via interference with TNFα-induced apoptotic hepatocyte death. These results demonstrate that GL rapidly attenuates APAP-induced liver injury by directly inhibiting TNFα-induced hepatocyte apoptosis. The protective effect against APAP-induced liver toxicity by GL in mice suggests the therapeutic potential of GL for the treatment of APAP overdose.

MiR-27a ameliorates inflammatory damage to the blood-spinal cord barrier after spinal cord ischemia: reperfusion injury in rats by downregulating TICAM-2 of the TLR4 signaling pathway

Background

Spinal cord ischemia reperfusion (IR) injury causes inflammation and subsequently increases blood-spinal cord barrier leakage and Toll-like receptor 4 (TLR₄) pathway activation. MicroRNAs (miRs) effectively regulate numerous target mRNAs during ischemia. However, their roles during IR injury are poorly understood. We investigated miRs involvement, particularly miR-27a, in TLR₄ pathway-mediated inflammatory responses after IR.

Method

We used a genomics approach to examine changed miRs of rats that had undergone 14 minutes of ischemia, followed by 24 or 72 hours of reperfusion. Quantitative RT-PCR was used to identify and confirm the miRs involved in regulating TLR₄ pathway activation. We scanned miR databases for potential miR targets and confirmed these targets by quantitative RT-PCR. The miR mimic and anti-miR oligonucleotides (AMOs) were intrathecally injected at 12-hour intervals beginning three days before the ischemia. The effects of miRs on the TLR₄ pathway and downstream cytokines were analyzed by PCR, western blotting, and ELISA. Double immunofluorescence staining was perfumed to determine the relationship between the targets and TLR₄. Blood-spinal cord barrier (BSCB) permeability was examined using Evans blue (EB) dye.

Results

A microarray analysis revealed that at 24 hours post-injury, three miRs were upregulated (>2.0 fold) and 15 miRs were downregulated (<0.5 fold), and at 72 hours, four miRs were upregulated and 14 were downregulated compared to their levels in sham-operated controls. We focused on miR-27a, which is predicted to contain sequences complementary to the 3'-untranslated region (UTR) of Toll-like receptor adaptor molecule 2 (TICAM-2). Double immunostaining indicated that TLR₄ activation correlated with changes in TICAM-2 expression. Compared to the rats in the IR and negative control groups, intrathecal infusion of the miR-27a mimic attenuated IR-induced TLR₄ activation and inflammatory damage to the BSCB, which was shown as decreased EB extravasation and lower levels of nuclear factor kappa-B (NF-κB) and lnterleukin (IL)-1β at 24 and 72 hours after reperfusion, whereas pretreatment with miR-27a AMO aggravated these injuries.

Conclusions

We present the first evidence that miRs play an important role in spinal cord IR injury. We identified TICAM-2 as a novel target of miR-27a. miR-27a upregulation attenuates IR-induced inflammatory damage to the BSCB by negatively regulating TICAM-2 of the TLR₄ signaling pathway and inhibiting the NF-κB/IL-1β pathway. These results provide new therapeutic targets for IR injury treatment.

Glycyrrhizic acid in the treatment of liver diseases: literature review

Glycyrrhizic acid (GA) is a triterpene glycoside found in the roots of licorice plants (Glycyrrhiza glabra). GA is the most important active ingredient in the licorice root, and possesses a wide range of pharmacological and biological activities. GA coupled with glycyrrhetinic acid and 18-beta-glycyrrhetic acid was developed in China or Japan as an anti-inflammatory, antiviral, and antiallergic drug for liver disease. This review summarizes the current biological activities of GA and its medical applications in liver diseases. The pharmacological actions of GA include inhibition of hepatic apoptosis and necrosis; anti-inflammatory and immune regulatory actions; antiviral effects; and antitumor effects. This paper will be a useful reference for physicians and biologists researching GA and will open the door to novel agents in drug discovery and development from Chinese herbs. With additional research, GA may be more widely used in the treatment of liver diseases or other conditions.

Glycyrrhizin protects mice against renal ischemia-reperfusion injury through inhibition of apoptosis and inflammation by downregulating p38 mitogen-activated protein kinase signaling

Ischemia-reperfusion (I/R) often leads to acute kidney injury, chronic renal failure and kidney transplantation failure. Glycyrrhizin is extracted from Glycyrrhiza glabra roots and is the predominant active component, which exhibits anti-inflammatory effects. However, to the best of our knowledge, the effect of glycyrrhizin on I/R-induced renal injury has not been investigated. In the present study, glycyrrhizin was demonstrated to attenuate renal I/R injury in mice via administration of glycyrrhizin, which suppressed the serum levels of creatinine and blood urea nitrogen 6 h following reperfusion; furthermore, the superoxide anions as well as the activity of superoxide dismutase within renal tissues was reduced by glycyrrhizin pretreatment. Moreover, the protein level of cleaved caspase-3, as well as its activity in renal tissue, was suppressed as a result of the glycyrrhizin pretreatment, indicating that glycyrrhizin inhibits I/R-induced renal cell apoptosis. In addition, glycyrrhizin pretreatment appeared to ameliorate I/R-induced renal injury via inhibition of inflammatory cell infiltration, as well as the production of pro-inflammatory cytokines, including tumor necrosis factor-α, interferon-γ, interleukin (IL)-1β and IL-6. The underlying molecular mechanism was investigated and it was shown that the activity of p38 mitogen-activated protein kinase signaling was downregulated as a result of glycyrrhizin administration. In conclusion, the present study indicated that glycyrrhizin provided significant protection against I/R-induced renal injury in mice by inhibiting inflammatory responses and renal cell apoptosis. Therefore, glycyrrhizin may be used in abdominal surgery and kidney transplantation for the prevention of renal I/R damage.

Glycyrrhizin alleviates neuroinflammation and memory deficit induced by systemic lipopolysaccharide treatment in mice

The present study investigated the effects of glycyrrhizin (GRZ) on neuroinflammation and memory deficit in systemic lipopolysaccharide (LPS)-treated C57BL/6 mice. Varying doses of GRZ was orally administered (10, 30, or 50 mg/kg) once a day for 3 days before the LPS (3 mg/kg) injection. At 24 h after the LPS injection, GRZ significantly reduced TNF-α and IL-1β mRNA at doses of 30 and 50 mg/kg. COX-2 and iNOS protein expressions were significantly reduced by GRZ at doses of 30 and 50 mg/kg. In the Morris water maze test, GRZ (30 mg/kg) significantly prolonged the swimming time spent in the target and peri-target zones. GRZ also significantly increased the target heading and memory score numbers. In the hippocampal tissue, GRZ significantly reduced the up-regulated Iba1 protein expression and the average cell size of Iba1-expressing microglia induced by LPS. The results indicate that GRZ ameliorated the memory deficit induced by systemic LPS treatment and the effect of GRZ was found to be mediated through the inhibition of pro-inflammatory mediators and microglial activation in the brain tissue. This study supports that GRZ may be a putative therapeutic drug on neurodegenerative diseases associated with cognitive deficits and neuroinflammation such as Alzheimer's disease.