Inhibiton of NF-kappaB activation during ischemia reduces hepatic ischemia/reperfusion injury in rats

Congestive ischemic colitis successfully treated with anti-inflammatory therapy: A case report

BACKGROUND

Congestive ischemic colitis is a rare subtype of ischemic colitis with an unknown pathophysiology. Excluding conservative management, such as fasting, no established treatment exists; therefore, surgical intervention should be considered in some cases if symptoms worsen. Current literature suggests that anti-inflammatory agents may effectively treat congestive ischemic colitis.

CASE SUMMARY

We present the case of a 68-year-old female patient who underwent laparoscopic left hemicolectomy for transverse colon cancer 3 years ago. Postoperatively, follow-up included an annual colonoscopy and abdominal computed tomography (CT) at a local clinic. However, progressive erythema and edema of the sigmoid colon were observed 1 year postoperatively. Upon admission to our hospital, she complained of abdominal pain and diarrhea. Abdominal CT showed thickening of the sigmoid colon walls, and colonoscopy revealed erythema, edema, and multiple ulcers with exudate in the sigmoid colon. CT angiography showed engorgement of the sigmoid vasa recta without any vascular abnormalities. The diagnosis was congestive ischemic colitis, and we treated the patient with anti-inflammatory agents. After 2 mo of glucocorticoid therapy (20 mg once daily) and 7 mo of 5-aminosalicylate therapy (1 g twice daily), the ulcers completely healed. She has not experienced any recurrence for 2 years.

CONCLUSION

Anti-inflammatory therapy, specifically glucocorticoids and 5-aminosalicylate, has demonstrated promising efficacy and introduces potential novel treatment options for congestive ischemic colitis.

Zinc accumulation aggravates cerebral ischemia/reperfusion injury by promoting inflammation

Intracellular zinc accumulation has been shown to be associated with neuronal death after cerebral ischemia. However, the mechanism of zinc accumulation leading to neuronal death in ischemia/reperfusion (I/R) is still unclear. Intracellular zinc signals are required for the production of proinflammatory cytokines. The present study investigated whether intracellular accumulated zinc aggravates I/R injury through inflammatory response, and inflammation-mediated neuronal apoptosis. Male Sprague-Dawley rats were treated with vehicle or zinc chelator TPEN 15 mg/kg before a 90-min middle cerebral artery occlusion (MCAO). The expressions of proinflammatory cytokines TNF-α, IL-6, NF-κB p65, and NF-κB inhibitory protein IκB-α, as well as anti-inflammatory cytokine IL-10 were assessed at 6 or 24 h after reperfusion. Our results demonstrated that the expression of TNF-α, IL-6, and NF-κB p65 increased after reperfusion, while the expression of IκB-α and IL-10 decreased, suggesting that cerebral ischemia triggers inflammatory response. Furthermore, TNF-α, NF-κB p65, and IL-10 were all colocalized with the neuron-specific nuclear protein (NeuN), suggesting that the ischemia-induced inflammatory response occurs in neurons. Moreover, TNF-α was also colocalized with the zinc-specific dyes Newport Green (NG), suggesting that intracellular accumulated zinc might be associated with neuronal inflammation following cerebral I/R. Chelating zinc with TPEN reversed the expression of TNF-α, NF-κB p65, IκB-α, IL-6, and IL-10 in ischemic rats. Besides, IL-6-positive cells were colocalized with TUNEL-positive cells in the ischemic penumbra of MCAO rats at 24 h after reperfusion, indicating that zinc accumulation following I/R might induce inflammation and inflammation-associated neuronal apoptosis. Taken together, this study demonstrates that excessive zinc activates inflammation and that the brain injury caused by zinc accumulation is at least partially due to specific neuronal apoptosis induced by inflammation, which may provide an important mechanism of cerebral I/R injury.

Effects and mechanisms of 6-hydroxykaempferol 3,6-di-O-glucoside-7-O-glucuronide from Safflower on endothelial injury in vitro and on thrombosis in vivo

Background: The florets of Carthamus tinctorius L. (Safflower) is an important traditional medicine for promoting blood circulation and removing blood stasis. However, its bioactive compounds and mechanism of action need further clarification.

Objective: This study aims to investigate the effect and possible mechanism of 6-hydroxykaempferol 3,6-di-O-glucoside-7-O-glucuronide (HGG) from Safflower on endothelial injury in vitro, and to verify its anti-thrombotic activity in vivo.

Methods: The endothelial injury on human umbilical vein endothelial cells (HUVECs) was induced by oxygen-glucose deprivation followed by reoxygenation (OGD/R). The effect of HGG on the proliferation of HUVECs under OGD/R was evaluated by MTT, LDH release, Hoechst-33342 staining, and Annexin V-FITC apoptosis assay. RNA-seq, RT-qPCR, Enzyme-linked immunosorbent assay and Western blot experiments were performed to uncover the molecular mechanism. The anti-thrombotic effect of HGG in vivo was evaluated using phenylhydrazine (PHZ)-induced zebrafish thrombosis model.

Results: HGG significantly protected OGD/R induced endothelial injury, and decreased HUVECs apoptosis by regulating expressions of hypoxia inducible factor-1 alpha (HIF-1α) and nuclear factor kappa B (NF-κB) at both transcriptome and protein levels. Moreover, HGG reversed the mRNA expression of pro-inflammatory cytokines including IL-1β, IL-6, and TNF-α, and reduced the release of IL-6 after OGD/R. In addition, HGG exhibited protective effects against PHZ-induced zebrafish thrombosis and improved blood circulation.

Conclusion: HGG regulates the expression of HIF-1α and NF-κB, protects OGD/R induced endothelial dysfunction in vitro and has anti-thrombotic activity in PHZ-induced thrombosis in vivo.

Pre-Ischemic Hypothermic Oxygenated Perfusion Alleviates Protective Molecular Markers of Ischemia-Reperfusion Injury in Rat Liver

To expand the pool of organs, hypothermic oxygenated perfusion (HOPE), one of the most promising perfusion protocols, is currently performed after cold storage (CS) at transplant centers (HOPE-END). We investigated a new timing for HOPE, hypothesizing that performing HOPE before CS (HOPE-PRE) could boost mitochondrial protection allowing the graft to better cope with the accumulation of oxidative stress during CS. We analyzed liver injuries at 3 different levels. Histologic analysis demonstrated that, compared to classical CS (CTRL), the HOPE-PRE group showed significantly less ischemic necrosis compared to CTRL vs HOPE-END. From a biochemical standpoint, transaminases were lower after 2 hours of reperfusion in the CTRL vs HOPE-PRE group, which marked decreased liver injury. qPCR analysis on 37 genes involved in ischemia-reperfusion injury revealed protection in HOPE-PRE and HOPE-END compared to CTRL mediated through similar pathways. However, the CTRL vs HOPE-PRE group demonstrated an increased transcriptional level for protective genes compared to the CTRL vs HOPE-END group. This study provides insights on novel biomarkers that could be used in the clinic to better characterize graft quality improving transplantation outcomes.

Artemisinin protects against cerebral ischemia and reperfusion injury via inhibiting the NF-κB pathway

This study investigated whether artemisinin (ART) exerts a neuroprotective effect against cerebral ischemia/reperfusion (I/R) injury. Hypoxia-glucose deprivation and reoxygenation (OGD/R) of SH-SY5Y cells were used as the I/R injury model in vitro. Cell viability was determined using 3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyltetrazolium bromide assay, and lactate dehydrogenase (LDH) release was measured. Cell apoptosis and apoptosis-associated protein expression were determined via flow cytometry and western blotting, respectively. The levels of glutathione peroxidase, superoxide dismutase, catalase, and malondialdehyde were determined. The secretion of tumor necrosis factor-α and interleukin-1β was measured using ELISA. The activation of the nuclear factor kappa B (NF-κB) pathway was also determined. The indicated ART concentrations (0, 25, 50, 75, and 100 μM) had no significant effect on SH-SY5Y cell viability and LDH activity. ART promoted cell viability, reduced cell apoptosis, repressed cellular inflammation, and inhibited cellular oxidative stress and NF-κB signaling pathway in OGD/R-induced SH-SY5Y cells. In addition, all the protective effects of ART on OGD/R-induced SH-SY5Y cell injury were significantly reversed by an NF-κB agonist. In conclusion, ART protects neurons from OGD/R-induced damage in vitro by inhibiting the NF-κB signaling pathway. These results suggest that ART may be a potential agent for the treatment of cerebral I/R injury.

Sinomenine in Cardio-Cerebrovascular Diseases: Potential Therapeutic Effects and Pharmacological Evidences

Cardio-cerebrovascular diseases, as a major cause of health loss all over the world, contribute to an important part of the global burden of disease. A large number of traditional Chinese medicines have been proved effective both clinically and in pharmacological investigations, with the acceleration of the modernization of Chinese medicine. Sinomenine is the main active constituent of sinomenium acutum and has been generally used in therapies of rheumatoid arthritis and neuralgia. Varieties of pharmacological effects of sinomenine in cardio-cerebrovascular system have been discovered recently, suggesting an inspiring application prospect of sinomenine in cardio-cerebrovascular diseases. Sinomenine may retard the progression of atherosclerosis by attenuating endothelial inflammation, regulating immune cells function, and inhibiting the proliferation of vascular smooth muscle cells. Sinomenine also alleviates chronic cardiac allograft rejection relying on its anti-inflammatory and anti-hyperplastic activities and suppresses autoimmune myocarditis by immunosuppression. Prevention of myocardial or cerebral ischemia-reperfusion injury by sinomenine is associated with its modulation of cardiomyocyte death, inflammation, calcium overload, and oxidative stress. The regulatory effects on vasodilation and electrophysiology make sinomenine a promising drug to treat hypertension and arrhythmia. Here, in this review, we will illustrate the pharmacological activities of sinomenine in cardio-cerebrovascular system and elaborate the underlying mechanisms, as well as give an overview of the potential therapeutic roles of sinomenine in cardio-cerebrovascular diseases, trying to provide clues and bases for its clinical usage.

The effects of meldonium on the acute ischemia/reperfusion liver injury in rats

Acute ischemia/reperfusion (I/R) liver injury is a clinical condition challenging to treat. Meldonium is an anti-ischemic agent that shifts energy production from fatty acid oxidation to less oxygen-consuming glycolysis. Thus, we investigated the effects of a 4-week meldonium pre-treatment (300 mg/kg b.m./day) on the acute I/R liver injury in Wistar strain male rats. Our results showed that meldonium ameliorates I/R-induced liver inflammation and injury, as confirmed by liver histology, and by attenuation of serum alanine- and aspartate aminotransferase activity, serum and liver high mobility group box 1 protein expression, and liver expression of Bax/Bcl2, haptoglobin, and the phosphorylated nuclear factor kappa-light-chain-enhancer of activated B cells. Through the increased hepatic activation of the nuclear factor erythroid 2-related factor 2, meldonium improves the antioxidative defence in the liver of animals subjected to I/R, as proved by an increase in serum and liver ascorbic/dehydroascorbic acid ratio, hepatic haem oxygenase 1 expression, glutathione and free thiol groups content, and hepatic copper-zinc superoxide dismutase, manganese superoxide dismutase, catalase, glutathione peroxidase, and glutathione reductase activity. Based on our results, it can be concluded that meldonium represent a protective agent against I/R-induced liver injury, with a clinical significance in surgical procedures.

The long noncoding RNA NKILA protects against myocardial ischaemic injury by enhancing myocardin expression via suppressing the NF-κB signalling pathway

BACKGROUND

The lncRNA NKILA has been reported to interact with NF-κB and has an important role in various human diseases. However, the role of NKILA in myocardial ischaemic injury is still unknown.

METHODS

We established cell and animal models of myocardial ischaemic injury. We confirmed our findings by overexpressing NKILA, silencing myocardin and using an NF-κB pathway inhibitor in a hypoxia/reoxygenation (H/R) model of H9c2 cells. An animal model of ischaemia-reperfusion (I/R) injury was established by LAD ligation. Overexpression of NKILA was achieved by adeno-associated virus (AAV) injection through the tail vein. Annexin-V/PI staining and flow cytometric analysis were performed to test cell apoptosis. ELISAs were used to determine the secretion of inflammatory factors. TTC, HE and TUNEL staining were performed to study myocardial pathological injury. qRT-PCR or Western blotting were used to test the expression levels of NKILA, myocardin, the NF-κB pathway and apoptosis-related proteins.

RESULTS

H/R and I/R treatment significantly suppressed the expression of NKILA and activated the NF-κB pathway, resulting in the loss of myocardin. Overexpressing NKILA led to the suppression of the NF-κB pathway and successfully prevented the cell apoptosis and inflammatory responses caused by H/R stimulation in H9c2 cells. Silencing myocardin reversed the protective effect of NKILA and led to severe injury in the H9c2 cells that underwent H/R. Furthermore, the NF-κB pathway inhibitor BAY11-7028 reduced the H/R injury in H9c2 cells with little effect on NKILA expression. Similar results were confirmed in an animal model of myocardial I/R injury and showed that overexpression of NKILA inhibited I/R-triggered myocardial injury in vivo.

CONCLUSION

NKILA enhanced the expression of myocardin via inhibiting the NF-κB signalling pathway and preventing cell apoptosis and the inflammatory response of cardiomyocytes, thus ameliorating myocardial I/R injury.

Protective effect of pyrrolidine dithiocarbamate on isoniazid/rifampicin‑induced liver injury in rats

Isoniazid (INH) and rifampicin (RIF) continue to be first line anti‑tuberculosis (TB) drugs. However, the use of these drugs is associated with hepatotoxicity. Nuclear factor‑κB (NF‑κB) plays a crucial role in regulating immunity and inflammation. It has been reported that pyrrolidine dithiocarbamate (PDTC), an inhibitor of NF‑κB, exerts a hepatoprotective effect on acute and chronic liver damage. The aim of the present study was to explore the INH/RIF‑induced protective effects and mechanisms of PDTC on liver injury. Rats were intragastrically administered INH (50 mg/kg/day) and RIF (50 mg/kg/day) daily for 28 days. PDTC (50 mg/kg/day) was intraperitoneally injected 2 h after the co‑administration of INH and RIF to compare liver biochemical indicators in the serum, histopathological damage, NF‑κB activity, oxidative stress, hepatic mRNA expression of tumor necrosis factor (TNF)‑α, bile salt export pump (BSEP), and protein expression of BSEP. It was found that the inhibition of NF‑κB activation by PDTC treatment markedly alleviated liver biochemical and histological injury, decreased oxidative stress and mRNA levels of TNF‑α, and prevented decreases in BSEP mRNA and protein expression induced by the co‑administration of INH and RIF. Collectively, the present data suggested that INH/RIF‑induced liver injury is dependent on the activation of NF‑κB. PDTC exerted a therapeutic effect on INH/RIF‑induced liver injury by increasing BSEP expression, and exhibiting antioxidant and anti‑inflammatory activities.

Potential therapeutic roles of stem cells in ischemia-reperfusion injury

Ischemia-reperfusion injury (I/RI), produced by an initial interruption of organ blood flow and its subsequent restoration, contributes significantly to the pathophysiologies of stroke, myocardial infarction, renal I/RI, intestinal I/RI and liver I/RI, which are major causes of disability (including transplant failure) and even mortality. While the restoration of blood flow is required to restore oxygen and nutrient requirements, reperfusion often triggers local and systemic inflammatory responses and subsequently elevate the ischemic insult where the duration of ischemia determines the magnitude of I/RI damage. I/RI increases vascular leakage, changes transcriptional and cell death programs, drives leukocyte entrapment and inflammation and oxidative stress in tissues. Therapeutic approaches which reduce complications associated with I/RI are desperately needed to address the clinical and economic burden created by I/RI. Stem cells (SC) represent ubiquitous and uncommitted cell populations with the ability to self-renew and differentiate into one or more developmental 'fates'. Like immune cells, stem cells can home to and penetrate I/R-injured tissues, where they can differentiate into target tissues and induce trophic paracrine signaling which suppress injury and maintain tissue functions perturbed by ischemia-reperfusion. This review article summarizes the present use and possible protective mechanisms underlying stem cell protection in diverse forms of ischemia-reperfusion.

A Mouse Model of Hepatic Ischemia-Reperfusion Injury Demonstrates Potentially Reversible Effects on Hippocampal Neurons and Postoperative Cognitive Function

Background

This study aimed to investigate cognitive function, hippocampal neuronal changes, and the expression of inflammatory cytokines in a mouse model of hepatic ischemia-reperfusion injury.

Material/Methods

Sixty mice were divided into the sham group, which underwent surgery without vascular occlusion; the I/R1 group, with occlusion of the left hepatic artery and portal vein for 20 min, and reperfusion for 30 min; and the I/R2 group, with occlusion of the left hepatic artery and portal vein for 40 min, and reperfusion for 30 min. At postoperative day 4 and 11, ten mice from each group underwent the Morris water maze (MWM) task. Hippocampal tissues were stained for Nissl bodies. Expression of nuclear factor-κB (NF-κB) and choline acetyltransferase (ChAT) were quantified by immunohistochemistry. Serum tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) were measured by enzyme-linked immunosorbent assay (ELISA).

Results

Groups I/R1 and I/R2 showed a significantly increased latency in the MWM test between days 5–9, compared with the sham group (P<0.05), with no difference by day 11; the I/R2 group had an initial lower crossing frequency (P<0.05), with no difference by day 18. The I/R2 group showed reduced numbers of Nissl bodies in hippocampal neurons. The I/R1 and I/R2 groups had increased expression of NF-κB, TNF-α, and IL-1β and decreased ChAT. No differences between the groups were found in levels of NF-κB, TNF-α, IL-1β, or ChAT by day 18.

Conclusions

A mouse model of hepatic ischemia-reperfusion injury showed transient and reversible cognitive dysfunction, changes in hippocampal neurons, and expression of inflammatory cytokines.

The transfection of A20 gene prevents kidney from ischemia reperfusion injury in rats

Ischemia/reperfusion may induce inflammation and cell death through the nuclear factor (NF)‑κB signaling pathway. As a negative regulator of NF‑κB, zinc finger A20 exhibits anti-apoptotic and anti‑inflammatory effects in vitro. The present study was designed to upregulate A20 expression using an A20 transfection approach to investigate the in vivo protective effects of the A20 gene on renal ischemia reperfusion injury. The A20 gene was cloned into a pcDNA3.1 vector to construct the expression plasmid pcDNA3.1‑A20. The plasmid was wrapped with a liposome and injected intravenously into rats 48 h prior to establishing the models of renal ischemia reperfusion injury. Saline and the empty plasmid pcDNA3.1 were used as controls. Following 24 h post‑operation, A20 expression was determined using reverse transcription‑quantitative polymerase chain reaction and western blotting. The renal function and structure were assessed by analyzing the concentrations of serum creatinine (Scr), blood urea nitrogen (BUN) and histological features. Renal tissues were additionally examined for renal tubular cell apoptosis and NF‑κB activity. The results demonstrated that in vivo transfection of pcDNA3.1‑A20 induced renal A20 expression in rats. A20 overexpression in vivo significantly reduced renal injury as demonstrated by the improved levels of Scr and BUN and the reduction in histological damage. These improvements were accompanied by a suppression of renal proximal tubular epithelial cell apoptosis and an inhibition of NF‑κB activity. These results indicated that transfection of the A20 gene upregulates the expression of A20 in vivo and protects the kidneys from ischemia reperfusion injury via inhibition of the NF‑κB signal transduction pathway.

Caspase-Independent Apoptosis Induced by Reperfusion Following Ischemia without Bile Duct Occlusion in Rat Liver

The contribution of caspases to hepatic ischemia/reperfusion (I/R)-induced apoptosis has not been completely understood yet. Several studies have demonstrated increased caspase activity during I/R and the protective effect of caspase inhibitors against I/R injuries. However, reports with opposing results also exist. Herein, we examined the contribution of caspases to the I/R-induced hepatic apoptosis in rats using caspase inhibitors and specific substrates of caspases. Hepatic I/R was induced via a 2-h occlusion of the portal vein and the hepatic artery, without conducting bile duct occlusion. DNA laddering and terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate (dUTP) nick end-labeling (TUNEL)-positive cells were increased at 3 h after reperfusion. Pretreatment with caspase inhibitors (Z-Asp-2,6-dichlorobenzoyloxymethylketone (Z-Asp-cmk) 2 or 10 mg/kg intravenously (i.v.), 20 mg/kg intraperitoneally (i.p.), Z-Val-Ala-Asp(OMe)-fluoromethylketone (Z-VAD-fmk) 3 mg/kg i.v.) failed to reduce apoptosis induced by I/R. Interestingly, apoptosis induced by the portal triad (hepatic artery, portal vein, and bile duct) occlusion/reperfusion could be marginally attenuated using Z-Asp-cmk (2 mg/kg i.v.). The cleavage activity for Ac-DEVD-α-(4-methylcoumaryl-7-amide) (MCA), a caspase-3/7/8/9 substrate, was significantly increased by I/R. Conversely, the cleavage activities for Ac-DNLD-MCA and MCA-VDQVDGW[K-DNP]-NH₂, specific substrates for caspase-3 and -7 respectively, were decreased by I/R. Protein expression of the cellular inhibitor of apoptosis protein 2 (c-IAP2), an endogenous caspase inhibitor, was increased by ischemia. Nuclear translocation of the apoptosis-inducing factor (AIF), an initiator protein of caspase-independent apoptosis, was also increased during I/R. These results suggest that caspases are inhibited by c-IAP2 induced during ischemia and that AIF may be involved in initiation of apoptosis induced by hepatic I/R without bile duct occlusion.

Lutein protects against ischemia/reperfusion injury in rat skeletal muscle by modulating oxidative stress and inflammation

BACKGROUND

Lutein is an antioxidant compound with potential biological effects. The present study investigated the protective role of Lutein against I/R injury in skeletal muscle.

METHODS

Animals were divided into three groups. Group I - sham operated; Group II- IR injury- Hind limb ischemia was induced by clamping the common femoral artery and vein. After 4 h of ischemia, the clamp was removed and the animals underwent 2 h of reperfusion. Group III-Lutein + IR injury- Rats with Lutein treatment received intraperitoneal injection 1 h before reperfusion. The skeletal tissues were analyzed for oxidative stress parameters (reactive oxygen species, protein carbonylation and sulfhydryls, lipid peroxidation). Antioxidant status was determined by evaluating Nrf-2 levels and antioxidant enzyme activities. The inflammatory mechanism was determined through NF-κB and COX-2 expressions. Pro-inflammatory cytokines were determined by ELISA.

RESULTS

The results showed that Lutein treatment significantly decreased the oxidative stress by reducing reactive oxygen species, protein carbonylation and sulphydryls, lipid peroxidation. Further, the levels of Nrf-2 and antioxidant status was significantly declined during IR injury compared to sham operated rats. Lutein treatment reduced the oxidative stress by enhancing Nrf-2 levels and antioxidant status. Skeletal IR injury enhanced the inflammatory signaling by up regulating NF-κB, COX-2 and various pro-inflammatory cytokines. NF-κB, COX-2 expressions were down regulated by Lutein treatment.

CONCLUSION

The study shows that Lutein protects against skeletal IR injury by down regulating oxidative stress and inflammatory mechanisms.

SPA0355 attenuates ischemia/reperfusion-induced liver injury in mice

Hepatic ischemia/reperfusion (I/R) injury leads to oxidative stress and acute inflammatory responses that cause liver damage and have a considerable impact on the postoperative outcome. Much research has been performed to develop possible protective techniques. We aimed to investigate the efficacy of SPA0355, a synthetic thiourea analog, in an animal model of hepatic I/R injury. Male C57BL/6 mice underwent normothermic partial liver ischemia for 45 min followed by varying periods of reperfusion. The animals were divided into three groups: sham operated, I/R and SPA0355 pretreated. Pretreatment with SPA0355 protected against hepatic I/R injury, as indicated by the decreased levels of serum aminotransferase and reduced parenchymal necrosis and apoptosis. Liver synthetic function was also restored by SPA0355 as reflected by the prolonged prothrombin time. To gain insight into the mechanism involved in this protection, we measured the activity of nuclear factor-κB (NF-κB), which revealed that SPA0355 suppressed the nuclear translocation and DNA binding of NF-κB subunits. Concomitantly, the expression of NF-κB target genes such as IL-1β, IL-6, TNF-α and iNOS was significantly downregulated. Lastly, the liver antioxidant enzymes superoxide dismutase, catalase and glutathione were upregulated by SPA0355 treatment, which correlated with the reduction in serum malondialdehyde. Our results suggest that SPA0355 pretreatment prior to I/R injury could be an effective method to reduce liver damage.

Antioxidant Stress and Anti-Inflammation of PPARα on Warm Hepatic Ischemia-Reperfusion Injury

Hepatic ischemia-reperfusion (IR) injury is a serious clinical problem. Minimizing the adverse effect of ischemia-reperfusion injury after liver surgery or trauma is an urgent need. It has been proved that besides the effect of regulating the lipid and lipoprotein metabolism, PPARα also undertakes the task of organ protection. In this paper, related literature has been summarized and we come to the conclusion that administration of PPARα agonists can strengthen the antioxidant and anti-inflammation defense system by the upregulation of the expression of antioxidant enzymes and inhibition of NF-κB activity. This may provide a potential clinical treatment for hepatic ischemia-reperfusion injury.

Lobe-specific heterogeneity and matrix metalloproteinase activation after ischemia/reperfusion injury in rat livers

Studies assessing the effects of partial-hepatic ischemia/reperfusion (I/R) injury focused on the damage to the ischemic-lobe, whereas few data are available on non-ischemic lobe. This study investigated whether acute liver I/R does affect non-ischemic lobe function via modulation of extracellular matrix remodeling. Male Sprague-Dawley rats underwent left lateral- and median-lobe ischemia for 30 min and reperfusion for 60 min or sham operation. After reperfusion, blood samples and hepatic biopsies from both the ischemic (left-lobe, LL) and the non-ischemic lobe (right-lobe, RL) were collected. Serum hepatic enzymes and TNF-alpha, tissue matrix metalloproteinases (MMP-2, MMP-9), liver morphology, malondialdehyde (MDA), and myeloperoxidase (MPO) were evaluated. Liver I/R injury was confirmed by altered increased hepatic enzymes and TNF-alpha. I/R induced an altered morphology and an increase in MMP-2 and MMP-9 activity not only in left-ischemic lobe (LL) but also in the right-non-ischemic (RL) lobe. A lobar difference was detected for MDA formation and MPO activity in both sham and I/R submitted rats, with higher levels in the left lobe for both groups. This study indicates that an increase in MMPs, which may be TNF-alpha-mediated, occurs in both the ischemic- and the non-ischemic lobes; the heterogeneous lobe concentrations of MDA and MPO suggest that the random sampling of liver tissue should be avoided.

Ischemia-reperfusion injury in rat steatotic liver is dependent on NFκB P65 activation

BACKGROUND

Steatotic liver grafts tolerate ischemia-reperfusion (I/R) injury poorly, contributing to increased primary graft nonfunction following transplantation. Activation of nuclear factor kappa-B (NFκB) following I/R injury plays a crucial role in activation of pro-inflammatory responses leading to injury.

METHODS

We evaluated the role of NFκB in steatotic liver injury by using an orthotopic liver transplant (OLT) model in Zucker rats (lean to lean or obese to lean) to define the mechanisms of steatotic liver injury. Obese donors were treated with bortezomib to assess the role of NF-κB in steatotic liver I/R injury. Hepatic levels of NF-κB and pro-inflammatory cytokines were analyzed by ELISA. Serum transaminase levels and histopathological analysis were performed to assess associated graft injury.

RESULTS

I/R injury in steatotic liver results in significant increases in activation of NF-κB (40%, p<0.003), specifically the p65 subunit following transplantation. Steatotic donor pretreatment with proteasome inhibitor bortezomib (0.1mg/kg) resulted in significant reduction in levels of activated NF-κB (0.58±0.18 vs. 1.37±0.06O.D./min/10 μg protein, p<0.003). Bortezomib treatment also reduced expression of pro-inflammatory cytokines MIP-2 compared with control treated steatotic and lean liver transplants respectively (106±17.5 vs. 443.3±49.9 vs. 176±10.6 pg/mL, p=0.02), TNF-α (223.8±29.9 vs. 518.5±66.5 vs. 264.5±30.1 pg/2 μg protein, p=0.003) and IL-1β (6.0±0.91 vs. 19.8±5.2 vs. 5±1.7 pg/10 μg protein, p=0.02) along with a significant reduction in ALT levels (715±71 vs. 3712.5±437.5 vs. 606±286 U/L, p=0.01).

CONCLUSION

These results suggest that I/R injury in steatotic liver transplantation are associated with exaggerated activation of NFκB subunit p65, leading to an inflammatory mechanism of reperfusion injury and necrosis. Proteasome inhibition in steatotic liver donor reduces NFκB p65 activation and inflammatory I/R injury, improving transplant outcomes of steatotic grafts in a rat model.

Aggravation of post-ischemic liver injury by overexpression of A20, an NF-κB suppressor

BACKGROUND & AIMS

A20 is an intracellular ubiquitin-editing enzyme that plays an important role in the negative feedback regulation of NF-κB activation in response to a diverse range of stimuli. Liver ischemia/reperfusion injury is associated with rapid activation of NF-κB signaling, but the role of NF-κB in hepatic ischemia/reperfusion injury remains controversial. The NF-κB signaling pathway mediates both protective and deleterious effects in the liver. Here, we examined whether A20 inhibited or aggravated hepatic ischemia/reperfusion injury.

METHODS

We used IκBα super-repressor as a positive control and overexpressed A20 and IκBα super-repressor in the liver of C57BL/6 mice. Mice underwent 45min of partial hepatic ischemia and were then reperfused.

RESULTS

Protein level of A20 was increased after reperfusion. Mice subjected to ischemia/reperfusion injury showed increased NF-κB activation, as evidenced by phosphorylation of IκBα and nuclear translocation of NF-κB. Prior transfection with Ad-A20 or Ad-IκBα super-repressor attenuated NF-κB activation and aggravated liver injury. Serum aminotransferases and proinflammatory cytokines, hepatocellular necrosis, and hepatic neutrophil infiltration were markedly increased compared to those of uninfected or control virus infected mice. In addition, A20 abolished the beneficial effect of ischemic preconditioning.

CONCLUSIONS

Our results suggest that inhibition of NF-κB activation by A20 aggravated partial hepatic ischemia/reperfusion injury. Understanding how the NF-κB pathway plays a role in directing a clinical outcome may lead to better prospects of more rational approaches to reduce post-ischemic liver injury.

Endogenous leptin fluctuates in hepatic ischemia/reperfusion injury and represents a potential therapeutic target

AIM: To evaluate the role of leptin in the internal disorders during hepatic ischemia/reperfusion injury.

METHODS: A rat model of 70% hepatic ischemia/reperfusion injury was established, with groups of sham-operation (Sham), 60 min ischemia/60 min reperfusion (I60’R60’), I60’R150’, I60’R240’ and I60’R360’. Serum leptin was detected by a self-produced radioimmunoassay; serum glucose, total anti-oxidation capacity, myeloperoxidase, alanine transaminase and diamine oxidase were determined by relevant kits, while histological alterations and protein levels of leptin in the lung, liver and duodenum were examined by hematoxylin-eosin staining and immunohistochemistry. Spearman’s rank correlation between leptin and other variables or grading of tissue impairment were analyzed simultaneously.

RESULTS: Serum leptin in I60’R360’ was significantly higher than in Sham and I60’R240’ groups (both P < 0.05), serum glucose in I60’R360’ was higher than in Sham and I60’R150’ (both P < 0.05), and serum total anti-oxidation capacity in I60’R240’ and I60’R360’ were higher than in Sham (both P < 0.05) and I60’R150’groups (both P < 0.01). Serum myeloperoxidase in groups of I60’R240’ and I60’R360’ were lower than in I60’R150’group (both P < 0.05), serum alanine transaminase in the four reperfusion groups were higher than in the Sham group (all P < 0.05), while serum DAO in I60’R360’ was lower than in I60’R60’ (P < 0.05). Histological impairment in the lung, liver and duodenum at the early phase of this injury was more serious, but the impairment at the later phase was lessened gradually. Protein levels of leptin in the lung in the four reperfusion groups were significantly lower than in the Sham group (all P < 0.01), decreasing in the order of I60’R150’, I60’R60’, I60’R360’ and I60’R240’; the levels in the liver in I60’R60’ and I60’R240’ were higher than in the Sham group (both P < 0.01), while the levels in I60’R240’ and I60’R360’ were lower than in I60’R60’ (both P < 0.01); the levels in duodenum in I60’R240’ and I60’R360’ were higher than in Sham, I60’R60’ and I60’R150’ (all P < 0.01), while the level in I60’R150’ was lower than in I60’R60’ (P < 0.05). There was a significantly positive correlation between serum leptin and alanine transaminase (ρ = 0.344, P = 0.021), a significantly negative correlation between the protein level of leptin in the lung and its damage scores (ρ = -0.313, P = 0.036), and a significantly positive correlation between the protein level of leptin in the liver and its damage scores (ρ = 0.297, P = 0.047).

CONCLUSION: Endogenous leptin fluctuates in hepatic ischemia/reperfusion injury, exerts a potency to rehabilitate the internal disorders and represents a potential target for supportive therapy.

Role of NFkappaB in an animal model of complex regional pain syndrome-type I (CRPS-I)

NFkappaB is involved in several pathogenic mechanisms that are believed to underlie the complex regional pain syndrome (CRPS), including ischemia, inflammation and sensitization. Chronic postischemia pain (CPIP) has been developed as an animal model that mimics the symptoms of CRPS-I. The possible involvement of NFkappaB in CRPS-I was studied using CPIP rats. Under sodium pentobarbital anesthesia, a tourniquet was placed around the rat left ankle joint, producing 3 hours of ischemia, followed by rapid reperfusion (IR injury). NFkappaB was measured in nuclear extracts of muscle and spinal cord tissue using ELISA. Moreover, the anti-allodynic (mechanical and cold) effect was tested for systemic, intrathecal, or intraplantar treatment with the NFkappaB inhibitor pyrrolidine dithiocarbamate (PDTC). At 2 and 48 hours after IR injury, NFkappaB was elevated in muscle and spinal cord of CPIP rats compared to shams. At 7 days, NFkappaB levels were normalized in muscle, but still elevated in spinal cord tissue. Systemic PDTC treatment relieved mechanical and cold allodynia in a dose-dependent manner, lasting for at least 3 hours. Intrathecal-but not intraplantar-administration also relieved mechanical allodynia. The results suggest that muscle and spinal NFkappaB plays a role in the pathogenesis of CPIP and potentially of human CRPS.

PERSPECTIVE

Using the CPIP model, we demonstrate that NFkappaB is involved in the development of allodynia after a physical injury (ischemia and reperfusion) without direct nerve trauma. Since CPIP animals exhibit many features of human CRPS-I, this observation indicates a potential role for NFkappaB in human CRPS.

Antioxidant effects of xanthohumol and functional impact on hepatic ischemia-reperfusion injury

Therapeutic effects of dietary flavonoids have been attributed mainly to their antioxidant capacity. Xanthohumol (1), a prominent flavonoid of the hop plant, Humulus lupulus, was investigated for its antioxidant potential and for its effect on NF-kappaB activation. To examine the biological relevance of 1, a hepatic ischemia/reperfusion model was chosen as a widely accepted model of oxidative stress generation. The impact of 1 on endogenous antioxidant systems, on the NF-kappaB signal transduction pathway as well as on apoptotic parameters, and on hepatic tissue damage was evaluated. Compound 1 markedly decreased the level of reactive oxygen species in vitro. Furthermore, levels of enzymatic and nonenzymatic antioxidants were restored after pretreatment in postischemic hepatic tissue, and lipid peroxidation was attenuated. NF-kappaB activity was reduced in vitro as well as in hepatic tissue after ischemia/reperfusion upon pretreatment with 1. In addition, the phosphorylation of Akt was markedly inhibited. Surprisingly, 1 decreased the expression of the antiapoptotic protein Bcl-X and increased caspase-3 like-activity, a proapoptotic parameter. Moreover, hepatic tissue damage as well as TNF-alpha levels increased in xanthohumol-pretreated liver tissue after ischemia/reperfusion. In summary, xanthohumol did not protect against ischemia/reperfusion injury in rat liver, despite its antioxidant and NF-kappaB inhibitory properties.

Role of leptin in hepatic ischemia/reperfusion-induced intestinal injury of rats

AIM: To explore the changes of leptin in intestinal tract following hepatic ischemia/reperfusion (H-I/R), to investigate the association between these changes and H-I/R-induced intestinal injury, and to find out the role of leptin in H-I/R-induced intestinal injury.

METHODS: A 70% H-I/R model of rats was established, forming 5 groups including sham-operation and injury ones based on different reperfusion time. Enzyme-colorimetry was used to detect serum diamine oxidase activity after injury, hematoxylin-eosin staining and immunohistochemistry were applied to investigate pathological variations and leptin protein expressions in duodenum after injury, respectively, while reverse transcriptase-PCR was used to detect leptin mRNA expressions in duodenum after injury.

RESULTS: Compared with sham-operation group after injury, the four reperfusion groups showed no significant difference in serum diamine oxidase activity, but serum diamine oxidase level was significantly higher in 60 min ischemia/60 min reperfusion (I60'R60') group than in I60'R360' group (P = 0.0077). Pathological investigation suggested that duodenal impairments at the early phase of H-I/R were more serious, while the impairments at the later phase lessened gradually. Compared with leptin protein expression in duodenum of sham-operation group after injury, that of I60'R240' and I60'R360' groups increased significantly (0.126503 ± 0.005873, 0.129458 ± 0.003755 vs 0.079269 ± 0.001995, both P < 0.01), and the levels of reperfusion groups decreased in such order as I60'R360', I60'R240', I60'R60' and I60'R150' groups. Compared with leptin mRNA expression in duodenum of sham-operation group after injury, that of I60'R150' group decreased significantly (0.944 ± 0.033 vs 1.022 ± 0.011, P = 0.049), and it was significantly lower than the level of I60'R360' group.

CONCLUSION: The expression changes of leptin in intestinal tract after H-I/R are closely associated with intestinal injury, suggesting that leptin may be a protective factor of resisting H-I/R-induced intestinal injury.

Attenuation of liver ischemia/reperfusion induced apoptosis by epigallocatechin-3-gallate via down-regulation of NF-kappaB and c-Jun expression

INTRODUCTION

Hepatic ischemia/reperfusion (I/R) activates Kupffer cells and initiates severe oxidative stress with enhanced production of reactive oxygen species (ROS) and tumor necrosis factor-alpha (TNF-alpha). ROS and TNF-alpha mediate the expression of nuclear factors and kinases, activating the signal transduction pathway, and triggering apoptosis. The aim of our study was to evaluate the potential protective effect of (-)-epigallocatechin-3-gallate (EGCG) administration in inhibition of apoptosis by attenuating the expression of NF-kappaB, c-Jun, and caspase-3 in a model of severe hepatic I/R.

MATERIALS AND METHODS

Thirty Wistar rats were allocated into three groups. Sham operation, I/R, and I/R-EGCG 50mg/kg. Hepatic ischemia was induced for 60min by Pringle's maneuver. Malondialdehyde (MDA), myeloperoxidase (MPO), light histology, scanning electron microscopy, terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), and immunocytochemistry for NF-kappaB, c-Jun, caspase-3, analysis on liver specimens and aspartate (AST), and alanine (ALT) transferases analysis in serum, were performed 120min after reperfusion.

RESULTS

Apoptosis as indicated by TUNEL and caspase-3 was widely expressed in the I/R group but very limited in the EGCG treated group. Liver was stained positive for NF-kappaB and c-Jun in the I/R group but failed to be stained positive in the EGCG treated group. MDA, MPO, AST, and ALT showed marked increase in the I/R group and significant decrease in EGCG treated group. Significant alterations of liver specimens were observed by light histology and transmission electron microscopy whilst pretreatment with EGCG resulted in parenchymal preservation.

CONCLUSIONS

Administration of EGCG is likely to inhibit I/R-induced apoptosis and protect liver by down-regulating NF-kappaB and c-Jun signal transduction pathways.

Inhibition of intestinal ischemia/repurfusion induced apoptosis and necrosis via down-regulation of the NF-kB, c-Jun and caspace-3 expression by epigallocatechin-3-gallate administration

Intestinal ischemia/reperfusion (I/R) produces reactive oxygen species (ROS) activating signal transduction and apoptosis. The aim of this study was to evaluate the effect of (-)-epigallocatechin-3-gallate (EGCG) administration in inhibition of apoptosis by attenuating the expression of NF-kB, c-Jun and caspace-3 in intestinal I/R. Thirty male wistar rats were used. Group A sham operation, B I/R, C I/R-EGCG 50 mg/kg ip. Intestinal ischemia was induced for 60 min by clamping the superior mesenteric artery. Malondialdehyde (MDA), myeloperoxidase (MPO), light histology, Fragment End Labelling of DNA (TUNEL), immunocytochemistry for NF-kB, c-Jun and caspace-3 analysis in intestinal specimens were performed 120 min after reperfusion. Apoptosis as indicated by TUNEL and Caspace-3, NF-kB and c-Jun was widely expressed in I/R group but only slightly expressed in EGCG treated groups. MDA and MPO showed a marked increase in the I/R group and a significant decrease in the EGCG treated group. Light histology showed preservation of architecture in the EGCG treated group. In conclusion, EGCG pre-treatment is likely to inhibit intestinal I/R-induced apoptosis by down-regulating the expression of NF-kB, c-Jun and caspase-3.

Pyrrolidine dithiocarbamate inhibits induction of immunoproteasome and decreases survival in a rat model of amyotrophic lateral sclerosis

Pyrrolidine dithiocarbamate (PDTC), an inhibitor of nuclear transcription factor kappa-B (NF-kappaB) and an antioxidant, has beneficial effects in animal models of various diseases, including arthritis, brain ischemia, spinal cord injury, Alzheimer's disease, and Duchenne muscular dystrophy. Because inflammation and oxidative damage are also hallmarks of amyotrophic lateral sclerosis (ALS), we studied the effect of oral PDTC treatment on G93A-superoxide dismutase 1 (SOD1) transgenic (TG) rat model of human ALS and observed that PDTC treatment significantly decreases the survival. PDTC treatment evoked the end stage of the disease at 121 +/- 21 days, whereas untreated TG animals reached the end stage at 141 +/- 13 days (p < 0.01). The DNA binding activity of NF-kappaB was not altered in G93A-SOD1 TG rats by PDTC treatment. The copper concentration in the spinal cord was increased after PDTC treatment both in G93A-SOD1 TG and wild-type rats, suggesting that increased copper may enhance the neurotoxicity of mutant SOD1. The amount of ubiquitinated proteins were significantly higher and proteasomal activity was decreased in the spinal cords of PDTC-treated TG rats compared with other groups, suggesting that PDTC treatment decreases proteasome function. Immunoblotting and immunocytochemistry showed that the level of immunoproteasome but not constitutive proteasome was increased in glia of G93A-SOD1 TG rats along with disease development. PDTC treatment completely blocked the induction of immunoproteasome expression without affecting constitutive proteasome. These results suggest that PDTC acts as an immunoproteasome inhibitor in mutant SOD1 rats and that immunoproteasome may help the nervous system to cope with deleterious effects of SOD1-G93A mutation.