Remote effects of lower limb ischemia-reperfusion: impaired lung, unchanged liver, and stimulated kidney oxidative capacities

Effect of peripheral blood mononuclear cells on ischemia-reperfusion injury of sciatic nerve of adult male albino rat: histological, immunohistochemical, and ultrastructural study

Ischemia/reperfusion (I/R) injury of sciatic nerve is a serious condition that results in nerve fiber degeneration, and reperfusion causes oxidative injury. Peripheral blood mononuclear cells (PBMNCs) have neuroregenerative power. This study was carried out to evaluate the potential ameliorative effect of PBMNCs on changes induced by I/R injury of the sciatic nerve. Fifty adult male albino rats were divided into donor and experimental groups that were subdivided into four groups: group I (control group), group II received 50 µL PBNMCs once intravenously via the tail vein, group III rubber tourniquet was placed around their Rt hind limb root for 2 hours to cause ischemia, group IV was subjected to limb ischemia as group III, then they were injected with 50 ul PBMNCs as group II before reperfusion. I/R injury showed disorganization of nerve fascicles with wide spaces in between nerve fibers. The mean area of collagen fibers, iNOS immunoexpression, and number of GFAP-positive Schwann cells of myelinated fibers showed a highly significant increase, while a highly significant reduction in the G-ratio and neurofilament immunoexpression was observed. Myelin splitting, invagination, evagination, and myelin figures were detected. PBMNC-treated group showed a marked improvement that was confirmed by histological, immunohistochemical, and ultrastructural findings.

The Effect of Cerium Oxide (CeO2) on Ischemia-Reperfusion Injury in Skeletal Muscle in Mice with Streptozocin-Induced Diabetes

Objective: Lower extremity ischemia-reperfusion injury (IRI) may occur with trauma-related vascular injury and various vascular diseases, during the use of a tourniquet, in temporary clamping of the aorta in aortic surgery, or following acute or bilateral acute femoral artery occlusion. Mitochondrial dysfunction and increased basal oxidative stress in diabetes may cause an increase in the effects of increased reactive oxygen species (ROS) and mitochondrial dysfunction due to IRI. It is of great importance to examine therapeutic approaches that can minimize the effects of IRI, especially for patient groups under chronic oxidative stress such as DM. Cerium oxide (CeO2) nanoparticles mimic antioxidant enzymes and act as a catalyst that scavenges ROS. In this study, it was aimed to investigate whether CeO2 has protective effects on skeletal muscles in lower extremity IRI in mice with streptozocin-induced diabetes. Methods: A total of 38 Swiss albino mice were divided into six groups as follows: control group (group C, n = 6), diabetes group (group D, n = 8), diabetes-CeO2 (group DCO, n = 8), diabetes-ischemia/reperfusion (group DIR, n = 8), and diabetes-ischemia/reperfusion-CeO2 (group DIRCO, n = 8). The DCO and DIRCO groups were given doses of CeO2 of 0.5 mg/kg intraperitoneally 30 min before the IR procedure. A 120 min ischemia-120 min reperfusion period with 100% O2 was performed. At the end of the reperfusion period, muscle tissues were removed for histopathological and biochemical examinations. Results: Total antioxidant status (TAS) levels were found to be significantly lower in group DIR compared with group D (p = 0.047 and p = 0.022, respectively). In group DIRCO, total oxidant status (TOS) levels were found to be significantly higher than in group DIR (p < 0.001). The oxidative stress index (OSI) was found to be significantly lower in group DIR compared with group DCO (p < 0.001). Paraoxanase (PON) enzyme activity was found to be significantly increased in group DIR compared with group DCO (p < 0.001). The disorganization and degeneration score for muscle cells, inflammatory cell infiltration score, and total injury score in group DIRCO were found to be significantly lower than in group DIR (p = 0.002, p = 0.034, and p = 0.001, respectively). Conclusions: Our results confirm that CeO2, with its antioxidative properties, reduces skeletal muscle damage in lower extremity IRI in diabetic mice.

Effect of Selenium on Lung Injury Induced by Limb Ischemic Reperfusion Injury in Sprague-Dawley Rats

Purpose

: Ischemia-reperfusion injury (IRI) plays an important role in the pathophysiology of acute limb ischemia, leading to damage to distant organs, including the lungs. A complex mechanism is involved in the formation of reactive oxygen species (ROS), release of inflammatory mediators, and neutrophil activation. One strategy to reduce the damage is administering selenium, an antioxidant enzyme component that can bind ROS and protect cells. This study aimed to compare the degree of lung injury due to limb IRI in Sprague-Dawley (SD) rats with selenium administration versus those without selenium treatment.

Materials and Methods

: Fifteen male SD rats were divided into three groups: the control group (Group A), the ischemia-reperfusion with pre-reperfusion selenium (Group B), and the ischemia-reperfusion with post-reperfusion selenium (Group C). All animals underwent two hours of limb ischemia and three hours of reperfusion. Selenium was given intravenously at a dose of 0.2 mg/kg body weight. After reperfusion, lung specimens were histopathologically examined.

Results

: The median degree of lung injury was severe in Group A, mild in Group B, and moderate in Group C (P=0.01). Post hoc analysis revealed a significant difference in the degree of lung injury between Groups A and B (P=0.01), while a comparison between Groups A and C (P=0.06) and Groups B and C (P=0.31) revealed no significant difference.

Conclusion

: The administration of pre-reperfusion selenium significantly decreases lung injury induced by limb ischemia-reperfusion in SD rats.

A clinically-relevant mouse model that displays hemorrhage exacerbates tourniquet-induced acute kidney injury

Hemorrhage is a leading cause of death in trauma. Tourniquets are effective at controlling extremity hemorrhage and have saved lives. However, tourniquets can cause ischemia reperfusion injury of limbs, leading to systemic inflammation and other adverse effects, which results in secondary damage to the kidney, lung, and liver. A clinically relevant animal model is critical to understanding the pathophysiology of this process and developing therapeutic interventions. Despite the importance of animal models, tourniquet-induced lower limb ischemia/reperfusion (TILLIR) models to date lack a hemorrhage component. We sought to develop a new TILLIR model that included hemorrhage and analyze the subsequent impact on kidney, lung and liver injuries. Four groups of mice were examined: group 1) control, group 2) hemorrhage, group 3) tourniquet application, and group 4) hemorrhage and tourniquet application. The hemorrhagic injury consisted of the removal of 15% of blood volume through the submandibular vein. The tourniquet injury consisted of orthodontic rubber bands applied to the inguinal area bilaterally for 80 min. Mice were then placed in metabolic cages individually for 22 h to collect urine. Hemorrhage alone did not significantly affect transcutaneous glomerular filtration rate (tGFR), blood urea nitrogen (BUN) or urinary kidney injury molecule-1 (KIM-1) levels. Without hemorrhage, TILLIR decreased tGFR by 46%, increased BUN by 162%, and increased KIM-1 by 27% (p < 0.05 for all). With hemorrhage, TILLIR decreased the tGFR by 72%, increased BUN by 395%, and increased urinary KIM-1 by 37% (p < 0.05 for all). These differences were statistically significant (p < 0.05). While hemorrhage had no significant effect on TILLIR-induced renal tubular degeneration and necrosis, it significantly increased TILLIR-induced lung total injury scores and congestion, and fatty liver. In conclusion, hemorrhage exacerbates TILLIR-induced acute kidney injury and structural damage in the lung and liver.

Risk factors for severe acute kidney injury post complication after total arch replacement combined with frozen elephant trunk, in acute type A aortic dissection

Background

Total arch replacement with the frozen elephant trunk (TAR + FET) technique is a challenging approach for acute type A aortic dissection (ATAAD). Severe acute kidney injury (AKI) adversely affects the prognosis of hospitalized patients. The study aims to evaluate the incidence and risk factors of severe AKI.

Methods

We conducted a retrospective cross-sectional study of the records of ATAAD patients following TAR + FET, admitted between January 2013 and December 2018. A multivariate logistic regression model was used to identify predictors of severe postoperative AKI. Severe postoperative AKI was defined using the Kidney Disease Improving Global Outcomes criteria.

Results

The whole in-hospital mortality rate was 4.3%. Among 670 patients, major adverse outcomes were present in 169 patients (25.2%), 67 patients (10.0%) required renal replacement therapy (RRT), and 80 (11.9%) developed severe postoperative AKI. In-hospital mortality in the severe AKI group (13.8%) was 4.5 times higher than in the non-severe AKI group (3.1%). Compared with the non-severe AKI patients, the severe AKI patients had a higher incidence of major adverse outcomes (100% vs. 15.1%, P<0.001) and more frequent use of RRT (83.8% vs. 0.0%, P<0.001). Multivariate analysis revealed that severe postoperative AKI was predicted by advanced age [odds ratio (OR) =1.029; 95% confidence interval (CI): 1.002-1.056; P=0.032], lower limb symptoms (OR =4.384; 95% CI: 2.240-8.582; P<0.001), coronary artery involvement (OR =2.478; 95% CI: 1.432-4.288; P=0.001), preoperative postoperative serum creatinine (SCr) (OR =1.008; 95% CI: 1.003-1.013; P=0.001), and prolonged cardiopulmonary bypass (CPB) time (OR =1.011; 95% CI: 1.006-1.015; P<0.001).

Conclusions

There was a high incidence of severe AKI and high in-hospital mortality after TAR + FET in ATAAD patients. The risk factors for severe AKI in ATAAD patients undergoing TAR + FET were determined to help identify the high-risk patients and make rational treatment decisions.

CoenzymeQ10 and Ischemic Preconditioning Potentially Prevent Tourniquet-Induced Ischemia/Reperfusion in Knee Arthroplasty, but Combined Pretreatment Possibly Neutralizes Their Beneficial Effects

Tourniquet (TQ) use during total knee arthroplasty (TKA) induces ischemia/reperfusion (I/R) injury, resulting in mitochondrial dysfunction. This study aims to determine the effects of coenzyme Q10 (CoQ10) and ischemic preconditioning (IPC), either alone or in combination, on I/R-induced mitochondrial respiration alteration in peripheral blood mononuclear cells (PBMCs) and pain following TKA. Forty-four patients were allocated into four groups: control, CoQ10, IPC, and CoQ10 + IPC. CoQ10 dose was 300 mg/day for 28 days. IPC protocol was three cycles of 5/5-min I/R time. Mitochondrial oxygen consumption rates (OCRs) of PBMCs were measured seven times, at baseline and during ischemic/reperfusion phases, with XFe 96 extracellular flux analyzer. Postoperative pain was assessed for 48 h. CoQ10 improved baseline mitochondrial uncoupling state; however, changes in OCRs during the early phase of I/R were not significantly different from the placebo. Compared to ischemic data, IPC transiently increased basal OCR and ATP production at 2 h after reperfusion. Clinically, CoQ10 significantly decreased pain scores and morphine requirements at 24 h. CoQ10 + IPC abolished analgesic effect of CoQ10 and mitochondrial protection of IPC. In TKA with TQ, IPC enhanced mitochondrial function by a transient increase in basal and ATP-linked respiration, and CoQ10 provides postoperative analgesic effect. Surprisingly, CoQ10 + IPC interferes with beneficial effects of each intervention.

Tourniquet-induced lower limb ischemia/reperfusion reduces mitochondrial function by decreasing mitochondrial biogenesis in acute kidney injury in mice

The mechanisms by which lower limb ischemia/reperfusion induces acute kidney injury (AKI) remain largely uncharacterized. We hypothesized that tourniquet-induced lower limb ischemia/reperfusion (TILLIR) would inhibit mitochondrial function in the renal cortex. We used a murine model to show that TILLIR of the high thigh regions inflicted time-dependent AKI as determined by renal function and histology. This effect was associated with decreased activities of mitochondrial complexes I, II, V and citrate synthase in the kidney cortex. Moreover, TILLIR reduced mRNA levels of a master regulator of mitochondrial biogenesis PGC-1α, and its downstream genes NDUFS1 and ATP5o in the renal cortex. TILLIR also increased serum corticosterone concentrations. TILLIR did not significantly affect protein levels of the critical regulators of mitophagy PINK1 and PARK2, mitochondrial transport proteins Tom20 and Tom70, or heat-shock protein 27. TILLIR had no significant effect on mitochondrial oxidative stress as determined by mitochondrial ability to generate reactive oxygen species, protein carbonylation, or protein levels of MnSOD and peroxiredoxin1. However, TILLIR inhibited classic autophagic flux by increasing p62 protein abundance and preventing the conversion of LC3-I to LC3-II. TILLIR increased phosphorylation of cytosolic and mitochondrial ERK1/2 and mitochondrial AKT1, as well as mitochondrial SGK1 activity. In conclusion, lower limb ischemia/reperfusion induces distal AKI by inhibiting mitochondrial function through reducing mitochondrial biogenesis. This AKI occurs without significantly affecting PINK1-PARK2-mediated mitophagy or mitochondrial oxidative stress in the kidney cortex.

Ischemic postconditioning ameliorates acute kidney injury induced by limb ischemia/reperfusion via transforming TLR4 and NF-κB signaling in rats

BACKGROUND

The present study investigated the influence of ischemic postconditioning (I-postC) on the adjustment of renal injury after limb ischemia-reperfusion (I/R) injury, to elucidate the mechanisms of the Toll-like receptor 4 (TLR 4)/NF-κB signaling pathway using histopathological and immunohistochemical methods.

METHODS

Male Sprague-Dawley rats were randomly assigned to five groups (numbered from 1 to 5): the sham group (Group 1, only the anesthesia procedure was conducted without limb I/R), the I/R group (Group 2, 4 h of reperfusion was conducted following 4 h limb ischemia under anesthesia), the I/R + I-postC group (Group 3, 4 h of ischemia and 4 h of reperfusion was conducted; before perfusion, 5 min of limb ischemia and 5 min of reperfusion were performed in the rats and repeated 3 times), the I/R + TAK group (Group 4, rats were injected with TLR4 antagonist TAK through the caudal vein before limb ischemia and reperfusion under anesthesia), the TAK group (Group 5, rats were injected with TAK, and the anesthesia procedure was conducted without limb I/R). Histological changes in the kidney in different groups were observed, and the extent of tubular injury was assessed. Changes in biochemical indexes and the expression of inflammatory factors, TLR4, and NF-κB were also evaluated.

RESULTS

Compared with rats in the I/R group, the secretion of inflammatory factors and the expression levels of TLR4 and NF-κB were decreased in rats in the I/R + I-postC group. Histological analysis revealed renal injury, including inflammatory cell infiltration, dilatation of the tubuli lumen, congestion in glomerular capillaries, degeneration of tubuli epithelial cells, and necrosis was ameliorated by I-postC. Immunohistochemical studies showed that I/R-induced elevation in TLR4 and NF-κB expression was reduced by I-postC treatment. Moreover, the expression levels of TLR4, NF-κB, and inflammatory factors in rats in the I/R + TAK group were also decreased, and the renal pathological lesion was alleviated, which was similar to that in rats in the I/R + I-postC group.

CONCLUSIONS

The present findings suggest that I-postC can reduce tissue injury and kidney inflammation induced by limb I/R injury, possibly via inhibition of the TLR4 and NF-κB pathways.

Rapamycin inhibits LOC102553434-mediated pyroptosis to improve lung injury induced by limb ischemia-reperfusion

Limb ischemia reperfusion (I/R) triggers local or systemic injury, and whether the process is mediated by pyroptosis remains unclear, we aimed to explore whether pyroptosis was involved in the process of rapamycin alleviating lung injury induced by I/R and investigate the molecular mechanisms. The histopathology of lung injury induced by I/R was confirmed by hematoxylin-eosin (HE) staining, and malondialdehyde (MDA), superoxide dismutase (SOD), and the expression of pyroptosis related molecules were detected. RNA sequencing was used to mine key long non-coding RNAs (lncRNAs). The model of lipopolysaccharide (LPS)-induced L2 cell damage was also used to explore the effect and mechanism of rapamycin on lncRNA. Rapamycin treatment alleviated I/R-induced lung histopathologically injury and increased the concentration of MDA while decreased activity of SOD and expression of NLRP3, Caspase-1, interleukin-1β (IL-1β), and IL-18 in rat. A total of 63 differentially expressed lncRNAs (DElncRNAs) were identified from IR + Rap group compared with IR group, and these DElncRNAs were mainly involved in cell adhesion molecules (CAMs) and endocytosis pathway. The lncRNA LOC102553434 and its target gene MMP9 were most significantly up-regulated in I/R-injured rat. In vitro experiments showed that LPS induction caused a significant increase in LOC102553434, MMP9, IL-1β, and IL-18 in L2 cells, but rapamycin treatment significantly reversed the effects. After interfering with the expression of LOC102553434 in the LPS-injured cells pretreated with rapamycin, cell proliferation significantly increased, and the expression of MMP, NLRP3 and caspase-1 were significantly decreased. Rapamycin protects the lung from limb I/R injury by regulating LOC102553434 expression and inhibiting pyroptosis pathway. LOC102553434 plays a role in promoting pyroptosis and thus provides a target for clinical treatment of I/R-induced lung injury.

SUPPLEMENTARY INFORMATION

The online version contains supplementary material available at 10.1007/s13205-021-02708-9.

Direct kidney injury or lower extremity ischemia induced indirect kidney injury: Which one is more harmful for kidneys?

OBJECTIVES

The aim of this study was to investigate and compare the severity of kidney damage following lower limb ischemia-reperfusion and direct kidney ischemia-reperfusion.

METHODS

Thirty Sprague Dawley male rats were randomly divided into three groups; lower extremity ischemia-reperfusion group (Group 2), renal ischemia-reperfusion group (Group 3) and control (anesthesia and median laparotomy only) (Group 1). In group 3, 1-h ischemia was performed on the kidney and in group 2, 1-h ischemia was performed on the left lower extremity. This procedure was followed by reperfusion for 24 h. Renal tissues were removed after the reperfusion period and the groups were evaluated for glutathioneperoxidase activity, malondialdehyde and GSH levels, and furthermore, their histolopathological scores were calculated.

RESULTS

Renal malondialdehyde levels were significantly higher in Group 2 and Group 3 than they were in the Control group. There was no significant difference in renal malondialdehyde levels between Group 2 and Group 3. Kidney glutathione (GSH) levels were statistically lower in Group 2 and Group 3 than in the Control group. No statistically significant difference was found between Group 2 and Group 3 regarding their GSH levels. In histological evaluation, there was no statistically significant difference between Group 2 and Group 3 in terms of kidney damage score.

CONCLUSIONS

This study has identified that lower extremity ischemia induces remote kidney damage with similar features to kidney injury, occurring after direct kidney ischemia-reperfusion.

Renoprotective effect of edaravone in acute limb ischemia/reperfusion injury

Background

In this experimental study, we aimed to investigate the efficacy of edaravone on renal injury due to acute lower limb ischemia/reperfusion in a rat model.

Methods

Between June 2015 and August 2015, a total of 40 male Wistar rats were used in this study. The rats were randomly divided into the sham, ischemia/reperfusion, edaravone, and solvent groups (n=10 in each). The infrarenal abdominal aorta was clamped for 120 min and was, then, reperfused for 120 min after clamp removal. Edaravone was administered intravenously 30 min before the induction of ischemia. Serum and kidney tissue samples were subjected to biochemical and histopathological analyses.

Results

Edaravone decreased the serum and tissue malondialdehyde levels in the ischemia/reperfusion group. The serum superoxide dismutase activity in the edaravone group was significantly higher than the ischemia/reperfusion and solvent groups. The serum nitric oxide level in the ischemia/reperfusion group was numerically higher than the sham group. The serum nitric oxide level was decreased by edaravone. The serum nitric oxide level was lower in the edaravone group than the solvent group. The tissue nitric oxide level was significantly higher in the ischemia/reperfusion than the sham group. In the ischemia/ reperfusion group, the histopathological changes were improved by edaravone.

Conclusion

Edaravone ameliorated renal injury caused by lower-limb ischemia/reperfusion. Therefore, it can be used to ameliorate acute ischemia/reperfusion injury during aortic and peripheral vascular surgery.

Reperfusion Interval as a Prevention of Lung Injury Due to Limb Ischemia-Reperfusion After Application of Tourniquet in Murine Experimental Study

BACKGROUND

Tourniquet use is prevalent in the orthopaedic field to achieve a bloodless operating field, but it poses risks of local and systemic complications, including lung injury. This study aims to examine the effect of tourniquet application on the hindlimb of a rat to its lung.

MATERIALS AND METHODS

This is an experimental study with 48 male Wistar strain rats as samples. The rats were divided into group A (n = 24), killed directly after fracturization and tourniquet application, and group B (n = 24), killed 14 days post-procedure. Each group was divided into four: group A1/B1 (control group, three hours tourniquet application without reperfusion interval), A2/B2 (5-min reperfusion between 2-h and 1-h tourniquet application), A3/B3 (10-min reperfusion), and A4/B4 (15-min reperfusion). The lung tissue was examined histologically within ten high-power fields (400 × magnification). The severity of lung injury was measured using the Lung Injury Score (LIS). The oxidative damage was measured by determining the malondialdehyde (MDA) level, using the TBARS (thiobarbituric acid reactive substance assay) method.

RESULTS

There was a dose-dependent decrease of LIS and MDA in groups A and B with increasing reperfusion interval. Fifteen-minute reperfusion interval caused a 54.55% and 45.33% LIS reduction in groups A and B, respectively. All pair-wise group comparisons (p < 0.05) showed significant differences. Five-minute interval reduced the MDA level by 16.56% and 30.13% in groups A and B, respectively. All possible pair-wise comparisons in both groups A and B also showed a significant difference (p < 0.05).

CONCLUSIONS

Reperfusion interval is a possible clinical approach to mitigate the remote organ damage induced by limb ischemia-reperfusion injury.

How important is the damage to the liver after lower limb ischemia-reperfusion? An experimental study in a rat model

Background

The aim of this study was to compare the effect of lower extremity ischemia reperfusion on the liver and the effect of ischemiareperfusion on the liver itself in a rat model.

Methods

Thirty Sprague-Dawley male rats were randomly divided into three groups including 10 in each group: sham (Group 1), lower limb ischemia-reperfusion (Group 2), and liver ischemia-reperfusion (Group 3). In Group 2, one hour of left lower limb ischemia was performed. In Group 3, one hour of ischemia in the liver was performed, followed by 24 hours of reperfusion. After reperfusion, the liver tissues were removed, and the groups were evaluated biochemically and histologically.

Results

The liver malondialdehyde levels were significantly higher in Groups 2 and 3 than in the sham group (p<0.001). In Group 2, the malondialdehyde levels were significantly higher than in Group 3 (p=0.019). The glutathione levels in the liver were significantly lower in Groups 2 and 3 than in the sham group (p<0.001). However, the glutathione levels were significantly higher in Group 2 than in Group 3 (p=0.005). In the histological evaluation, although the liver damage score was higher in Group 3 than in Group 2 (p=0.015), there was no significant difference between the two groups in TUNEL(+) cell number (p>0.05).

Conclusion

Reperfusion injury in the liver after lower limb ischemiareperfusion is as important as ischemia-reperfusion injury which is specifically induced in the liver. This should be taken into account, particularly in reperfusion surgeries following vascular trauma or in cases of leg tourniquets to stop bleeding after lower limb vascular trauma.

Which Distant Organ is Most Affected by Lower Extremity Ischemia-Reperfusion?

BACKGROUND

It has been experimentally shown that reperfusion injury occurs in many remote organs after ischemia-reperfusion (I/R) of the lower extremity. However, which distant organ is affected more after I/R of the lower extremity has not been investigated. In this study, we investigate which remote organ is predominantly affected after lower extremity I/R.

METHODS

Twenty male Sprague-Dawley rats were randomly divided into 2 groups: sham (group 1) and lower extremity I/R (group 2). In group 2, 1 hr of ischemia of the left lower extremity was followed by 24 hr of reperfusion of the limb. After reperfusion, the lung, liver, kidney, heart, and small intestine tissues were harvested in both groups.

RESULTS

In the I/R group, the malondialdehyde levels were significantly higher in the heart and small intestine tissues than those in other tissues (P < 0.05). In addition, in the I/R group, the glutathione and glutathione peroxidase activities were also higher in the heart tissues than those in other tissues (P < 0.05). However, these results were not significant because the malondialdehyde, glutathione, and glutathione peroxidase levels of the heart tissues in the control group were higher than those of the other tissues. Therefore, no statistically significant difference was found between the tissues in terms of the histological damage score we created and the terminal deoxynucleotidyl transferase-mediated dUTP-biotin nick end labeling-positive cell numbers.

CONCLUSIONS

There was no difference in the severity of reperfusion injury between the tissues we examined after lower extremity I/R. This suggests that every distal organ should be carefully monitored after lower extremity I/R.

Downregulation of DLGAP1-Antisense RNA 1 Alleviates Vascular Endothelial Cell Injury Via Activation of the Phosphoinositide 3-kinase/Akt Pathway Results from an Acute Limb Ischemia Rat Model

OBJECTIVE

This study aimed to investigate the effect of long non-coding RNA (lncRNA) DLGAP1 antisense RNA 1 (DLGAP1-AS1) on vascular endothelial cell (VEC) injury via the phosphoinositide 3-kinase (PI3K)/Akt pathway in rat models of acute lower limb ischaemia-reperfusion (I/R).

METHODS

Differentially expressed lncRNAs related to I/R were screened using the gene expression omnibus database. Acute lower limb I/R models were induced in male Wistar rats, in which the regulatory mechanisms of DLGAP1-AS1 silencing were analysed after the treatment of small interfering RNA (siRNA) against DLGAP1-AS1 or an inhibitor of the PI3K/Akt pathway. The relationship between DLGAP1-AS1 and the PI3K/Akt pathway was analysed. The levels of tumour necrosis factor (TNF)-α and vascular cell adhesion molecule-1 (VCAM-1), as well as malondialdehyde (MDA) concentration and creatine kinase (CK) activity, were measured. The number of circulating endothelial cells (CECs) and apoptosis of VECs were identified.

RESULTS

Microarray based analysis indicated that DLGAP1-AS1 was highly expressed in I/R, which was further confirmed by detection of expression in rat models of acute lower limb I/R. Notably, the treatment of siRNA against DLGAP1-AS1 led to the activation of the PI3K/Akt pathway. In response to siRNA against DLGAP1-AS1, the levels of TNF-α and VCAM-1 were decreased, and MDA concentration and CK activity was downregulated. Reduced CEC numbers and suppressed VEC apoptosis were also observed.

CONCLUSION

DLGAP1-AS1 silencing could further suppress the oxidative stress, exert an anti-apoptosis effect, and reduce inflammatory reaction, whereby VEC injury is alleviated by activation of the PI3K/Akt pathway in rats with acute lower limb I/R.

Electroacupuncture Attenuates Limb Ischemia-Reperfusion-Induced Lung Injury Via p38 Mitogen-Activated Protein Kinase-Nuclear Factor Erythroid-2-Related Factor-2/Heme Oxygenase Pathway

BACKGROUND

Electroacupuncture has been reported to protect the body from organ damages, but its mechanisms remain to be explored. This research was designed to investigate the function of electroacupuncture in lung injury resulted from hind limb ischemia-reperfusion (LIR) and whether p38 mitogen-activated protein kinase (p38 MAPK)-mediated nuclear factor erythroid-2-related factor-2 (Nrf2)/heme oxygenase (HO)-1 pathway contributes to the protective effect of electroacupuncture on LIR-originated lung damage.

MATERIALS AND METHODS

Rabbits were subjected to occluding femoral artery for 2 h. Then they received reperfusion for 4 h to establish lung injury model. Electroacupuncture stimulation was performed bilaterally at Feishu and Zusanli acupoints for 15 min once a day for 5 d before the experiment and throughout the hind LIR model performing in the experimental day. Blood samples and lung tissues were collected to examine the role of electroacupuncture treatment in inflammatory response, oxidative stress, and lung injury. Both the protein expression and the messenger RNA level of Nrf2 and HO-1 were detected.

RESULTS

The results showed that electroacupuncture treatment remarkably alleviated lung injury, decreased inflammatory cytokines secretion, attenuated lung oxidative stress, increased the amount of Nrf2 and HO-1, and increased the ratio of phospho-p38 MAPK to p38 MAPK after LIR. However, the protective effects exerted by electroacupuncture were reversed to some extent by the preconditioning with SB203580, a p38 MAPK-specific inhibitor.

CONCLUSIONS

These results suggested that electroacupuncture could attenuate lung injury in rabbits subjected to LIR by inhibition of proinflammatory cytokine response and oxidative stress through activating p38 MAPK-mediated Nrf2/HO-1 pathway.

Protective effects of HO-1 pathway on lung injury subsequent to limb ischemia reperfusion

Limb ischemia reperfusion (LIR) can activate endogenous cytoprotective mechanisms by generating specific proteins against reperfusion injury in remote organs. The present study investigated the roles of heme oxygenase-1 (HO-1) pathway and the molecular mechanisms underlying the regulation of this pathway on lung injury following LIR. LIR was induced by ischemia for 4 hours followed by reperfusion for 6 hours (LIR 6 hours) or 16 hours (LIR 16 hours) in male Sprague-Dawley rats. HO-1 inducer cobalt protoporphyrin (Copp) or HO-1 inhibitor zinc protoporphyrin (Znpp) was intravenously injected 24 hours before ischemia. The animals were randomly divided into nine groups, including normal control, LIR 6 hours, LIR 16 hours, Copp, Copp + LIR 6 hours, Copp + LIR 16 hours, and Znpp, Znpp+ LIR 6 hours, and Znpp + LIR 16 hours groups (each group included four samples). Lung injury was examined through histopathology. Quantitative real-time PCR, immunohistochemistry and Western blot were applied to detect the mRNA and protein levels of HO-1, Nrf2, and Bach1. Our study showed that LIR induced Nrf2 upregulation but Bach1 downregulation to promote HO-1 expression in lung tissues. Activation of HO-1 pathway by Copp potentially enhanced Nrf2 expression but inhibition of the pathway by Znpp promoted Bach1 expression. Inducer of HO-1 pathway, Copp injection improved the lung injury. Nevertheless, Znpp injection aggravated the lung injury following LIR. Our findings suggested that activated HO-1 pathway might exert protective effects on the lung injury following LIR.

Nuclear Transcription Factor Kappa B (NF-кB) and Molecular Damage Mechanisms in Acute Cardiovascular Diseases. A Review

Worldwide, cardiovascular diseases (CVDs) represent one of the main causes of morbidity and mortality, and acute coronary syndromes are responsible for a large number of sudden cardiac deaths. One of the main challenges that still exist in this area is represented by the early detection and targeted monitoring of the pathophysiology involved in CVDs. During the last couple of years, researchers have highlighted the importance of molecular and epigenetic mechanisms involved in the initiation and augmentation of CVDs, culminating in their most severe form represented by acute myocardial infarction. One of the most studied molecular factors involved in this type of pathology is represented by nuclear transcription factor kappa B (NF-κB), as well as the involvement of microRNAs (miRNAs). It has been suggested that miRNAs can also be involved in the complex process of atheromatous plaque vulnerabilization that leads to an acute cardiac event. In this review paper, we describe the most important molecular mechanisms involved in the pathogenesis of CVDs and atheromatous plaque progression and vulnerabilization, which include molecular mechanisms dependent on NF-κB. For this paper, we used international databases (PubMed and Scopus). The keywords used for the search were “miRNAs biomarkers”, “miRNAs in cardiovascular disease”, “NF-κB in cardiovascular disease”, “molecular mechanism in cardiovascular disease”, and “myocardial NF-κB mechanisms”. Numerous molecular reactions that have NF-κB as a trigger are involved in the pathogenesis of CVDs. Moreover, miRNAs play an important role in initiating and aggravating certain segments of CVDs. Therefore, miRNAs can be used as biomarkers for early evaluation of CVDs. Furthermore, in the future, miRNAs could be used as a targeted molecular therapy in order to block certain mechanisms responsible for inducing CVDs and leading to acute cardiovascular events.

MicroRNA-19 restores vascular endothelial cell function in lower limb ischemia-reperfusion injury through the KLF10-dependent TGF-β1/Smad signaling pathway in rats

Ischemia-reperfusion injury (IRI) is a severe problem patients diagnosed with acute limb ischemia. Recently, microRNAs (miR) have emerged as regulators of IRI as well as ischemic preconditioning and ischemic postconditioning. Therefore, using rat models, this study aims to explore all of the possible mechanisms that miR-19 exhibits with its relation to the transforming growth factor beta (TGF-β1)/Smad signaling pathway in the lower limb IRI. An immunofluorescence staining method was used to identify the Krueppel-like factor 10 (KLF10) positive expression and the location of KLF10 expression. The targeting relationship that miR-19 has with KLF10 was verified by the dual-luciferase reporter gene assay. Vascular endothelial cells (VECs) were treated with elevated or suppressed miR-19 or KLF10 knockdown. A 3-(4, 5-dimethylthiazol-2-yl)-2, 5-diphenyltetrazolium bromide assay was used to test cell proliferation, and flow cytometry was employed to detect both cell cycle and apoptosis. The KLF10-positive expression in the VECs (both in cytoplasm and nucleus) was found to be elevated in the IRI rats. We found that miR-19 was downregulated, KLF10 upregulated, and the TGF-β1/Smad signaling pathway activated in the vascular epithelial tissues of IRI rats. KLF10 is a target gene of miR-19. Overexpression of miR-19 decreased the expression of KLF10, TGF-β1, and Smad2/3. Decreased miR-19 inhibited VEC proliferation, arrested VECs at the G1 phase, and promoted the apoptosis of VECs following their lower limb I/R injury. These results indicate miR-19 as being an inhibitor in the VEC injury of IRI via the TGF-β1/Smad signaling pathway by suppression of KLF10.

Effects of hyperbaric therapy on liver morphofunctional of rabbits (Oryctolagus cuniculus) after hind limb ischemia-reperfusion injury

AIM

The objective of this research was to study and to prove the effectiveness of hyperbaric oxygen therapy (HBOT) starting time on liver morphofunctional changes after ischemia-reperfusion in the hind limb of rabbits.

MATERIALS AND METHODS

This research used a complete randomized design with 4 groups and 6 repetitions on each. After 6 h artery femoral is ligation, reperfusion was performed for 100 min (G1), HBOT for 90 min after 10 min reperfusion (G2), 10 min reperfusion (G3), and HBOT 90 min after 60 min reperfusion (G4). Then, all of the rabbits were sacrificed. The liver and blood were taken for histopathological changes examination as well as for measuring the level of aspartate aminotransferase (AST) and alanine aminotransferase (ALT). The statistical test using Kruskal-Wallis and Mann-Whitney showed that the score of degeneration, necrosis, and portal inflammation in groups without HBOT (G1 and G3) were not significantly different, as well as in group with HBOT (G2 and G4) (p>0.05). However, the scores of histopathological changes in G1 and G3 were significantly different from those in G2 and G4 (p<0.05). The levels of AST and ALT in the groups without hyperbaric therapy (G1 and G3) were not significantly different from those in the groups treated with hyperbaric therapy (G2 and G4) (p>0.05).

RESULT

Hind limb ischemia injury reperfusion can trigger damage for liver morphology, but not lead to liver dysfunction. Reperfusion can trigger increased activity of neutrophils, while neutrophil infiltration in the organ will lead to dysfunction. HBOT can inhibit the activity of neutrophils and the dysfunction of organs caused by ischemic reperfusion.

CONCLUSION

HBOT for 90 min, both 10 and 60 min after the reperfusion, can protect hepatocytes from damage.

Muscles Susceptibility to Ischemia-Reperfusion Injuries Depends on Fiber Type Specific Antioxidant Level

Muscle injury resulting from ischemia-reperfusion largely aggravates patient prognosis but whether and how muscle phenotype modulates ischemia-reperfusion-induced mitochondrial dysfunction remains to be investigated. We challenged the hypothesis that glycolytic muscles are more prone to ischemia-reperfusion-induced injury than oxidative skeletal muscles. We therefore determined simultaneously the effect of 3 h of ischemia induced by aortic clamping followed by 2 h of reperfusion (IR, n = 11) on both gastrocnemius and soleus muscles, as compared to control animals (C, n = 11). Further, we investigated whether tempol, an antioxidant mimicking superoxide dismutase, might compensate a reduced defense system, likely characterizing glycolytic muscles (IR-Tempol, n = 7). In the glycolytic gastrocnemius muscle, as compared to control, ischemia-reperfusion significantly decreased mitochondrial respiration (-30.28 ± 6.16%, p = 0.003), increased reactive oxygen species production (+79.15 ± 28.72%, p = 0.04), and decreased reduced glutathione (-28.19 ± 6.80%, p = 0.011). Less deleterious effects were observed in the oxidative soleus muscle (-6.44 ± 6.30%, +4.32 ± 16.84%, and -8.07 ± 10.84%, respectively), characterized by enhanced antioxidant defenses (0.63 ± 0.05 in gastrocnemius vs. 1.24 ± 0.08 μmol L^-1 g^-1 in soleus). Further, when previously treated with tempol, glycolytic muscle was largely protected against the deleterious effects of ischemia-reperfusion. Thus, oxidative skeletal muscles are more protected than glycolytic ones against ischemia-reperfusion, thanks to their antioxidant pool. Such pivotal data support that susceptibility to ischemia-reperfusion-induced injury differs between organs, depending on their metabolic phenotypes. This suggests a need to adapt therapeutic strategies to the specific antioxidant power of the target organ to be protected.

Modulatory effect of silymarin on pulmonary vascular dysfunction through HIF-1α-iNOS following rat lung ischemia-reperfusion injury

Silymarin is a traditional therapeutic used to protect the liver, acting to oppose lipid peroxidation, to enhance liver regeneration and functioning as an antioxidant. However, the effects of silymarin on pulmonary vascular dysfunction have not been investigated. In the present study, the modulatory effects of silymarin on pulmonary vascular dysfunction and the underlying mechanisms behind this were investigated in a lung ischemia-reperfusion (I/R) injury rat model. Male Sprague Dawley rats were randomly divided into 3 groups, including: i) A control group (n=10); ii) an I/R group (n=10); and iii) a silymarin-treated group (n=10). All experimental rats received 250 mg/kg/day of silymarin for 8 days. Silymarin was demonstrated to markedly improve lung I/R-induced pulmonary vascular dysfunction and lung moisture. Following silymarin treatment, inflammation and oxidative stress in the lung I/R-injury rats were demonstrably suppressed. Treatment with silymarin also inhibited the activation of caspase-3 and -9, and hypoxia inducible factor-1α (HIF-1α) and inducible nitric oxide synthase (iNOS) protein expression in the lung I/R-injury rats. Silymarin was concluded to impact upon pulmonary vascular dysfunction through the HIF-1α-iNOS pathway in the lung I/R injury rat model.

Cepharanthine alleviates liver injury in a rodent model of limb ischemia-reperfusion

OBJECTIVES

Limb ischemia-reperfusion (I/R) causes remote organ injury (e.g., liver injury). Oxidation and inflammation are crucial mechanisms. We investigated the effects of cepharanthine, a potent antioxidative and anti-inflammatory drug, on alleviating liver injury induced by limb I/R.

METHODS

Twenty-four adult male Sprague-Dawley rats were randomized to receive sham operation (Sham), Sham plus cepharanthine, I/R, or I/R plus cepharanthine and designated as the Sham, Sham+Cep, I/R, or I/R+Cep group, respectively (n = 6 in each group). I/R was induced by applying rubber band tourniquets high around each hind limb for 3 hours followed by reperfusion for 24 hours.

RESULTS

The plasma levels of aspartate aminotransferase (AST) and alanine aminotransferase (ALT) of the Sham and Sham+Cep groups were low, and the levels of AST and ALT of the I/R group were significantly higher than those of the Sham group (both p<0.001). By contrast, the AST and ALT of the I/R+Cep group were significantly lower than those of the I/R group (both p<0.001). The hepatic levels of nitric oxide (NO), malondialdehyde (MDA), macrophage inflammatory protein 2 (MIP-2), interleukin-6 (IL-6), and cyclooxygenase-2 (COX-2)/prostaglandin E2 (PGE2) of the Sham and Sham+Cep groups were also low. As expected, the NO, MDA, MIP-2, IL-6, and COX-2/PGE2 of the I/R group were significantly higher than those of the Sham group (all p<0.001). By contrast, the NO, MDA, MIP-2, IL-6, and COX-2/PGE2 of the I/R+Cep group were significantly lower than those of the I/R group (all p<0.05).

CONCLUSION

Cepharanthine alleviates liver injury in a rodent model of limb I/R. The mechanisms may involve reducing oxidation and inflammation.

Inhibition of reactive oxygen species downregulates the MAPK pathway in rat spinal cord after limb ischemia reperfusion injury

INTRODUCTION

We examined the activity of mitogen-activated protein kinase (MAPK) family members, extracellular signal-regulated kinase (ERK), c-Jun N-terminal kinase (JNK), and p38, in rats pinal cord after hind limb ischemia reperfusion (IR) and analyzed the role of reactive oxygen species (ROS) as mediators of MAPK signaling under these conditions.

METHODS

In experiment 1, hind limb IR rats were treated intraperitoneally with one of following agents at 30 min before reperfusion: allopurinol (4, 40 mg/kg), superoxide dismutase (SOD, 4000 U/kg), N-nitro-l-arginine methyl ester (l-NAME, 10 mg/kg), or SOD (4000 U/kg) + l-NAME (10 mg/kg). In experiment 2, 5,10,15,20-tetrakis (N-methyl-4'-pyridyl) porphyrinato iron (III) (FeTMPyP) was administered intraperitoneally (1, 3, or 10 mg/kg) 30 min before reperfusion. After 3 d reperfusion period, the spinal cord (L4-6) was harvested to investigate MAPK signaling activity.

RESULTS

In experiment 1, p-ERK and p-JNK levels were significantly higher in the IR group than sham group. Administration of allopurinol, SOD, l-NAME, or SOD + l-NAME significantly reduced the IR-induced increase in p-ERK and p-JNK levels. There were no significant differences in p-p38 levels. In experiment 2, FeTMPyP significantly reduced the IR-induced increase in p-ERK and p-JNK levels in a dose-dependent manner.

CONCLUSIONS

Activation of ERK and JNK in the spinal cord was induced by hind limb IR and was not accompanied by p38 activation. IR-induced MAPK phosphorylation was reduced by inhibition of superoxide, nitric oxide, and peroxynitrite, indicating that ROS produced by hind limb IR mediate the activation of these signaling pathways in the spinal cord, potentially affecting distant organs.

Tetrahydrocannabinol induces brain mitochondrial respiratory chain dysfunction and increases oxidative stress: a potential mechanism involved in cannabis-related stroke

Cannabis has potential therapeutic use but tetrahydrocannabinol (THC), its main psychoactive component, appears as a risk factor for ischemic stroke in young adults. We therefore evaluate the effects of THC on brain mitochondrial function and oxidative stress, key factors involved in stroke. Maximal oxidative capacities V_max (complexes I, III, and IV activities), V_succ (complexes II, III, and IV activities), V_tmpd (complex IV activity), together with mitochondrial coupling (V_max/V₀), were determined in control conditions and after exposure to THC in isolated mitochondria extracted from rat brain, using differential centrifugations. Oxidative stress was also assessed through hydrogen peroxide (H₂O₂) production, measured with Amplex Red. THC significantly decreased V_max (−71%; P < 0.0001), V_succ (−65%; P < 0.0001), and V_tmpd (−3.5%; P < 0.001). Mitochondrial coupling (V_max/V₀) was also significantly decreased after THC exposure (1.8±0.2 versus 6.3±0.7; P < 0.001). Furthermore, THC significantly enhanced H₂O₂ production by cerebral mitochondria (+171%; P < 0.05) and mitochondrial free radical leak was increased from 0.01±0.01 to 0.10±0.01% (P < 0.001). Thus, THC increases oxidative stress and induces cerebral mitochondrial dysfunction. This mechanism may be involved in young cannabis users who develop ischemic stroke since THC might increase patient's vulnerability to stroke.