Apoptosis in ischemia/reperfusion injury of human renal allografts

Intrarenal Anti-Leptin Treatment Attenuates Ischemia and Reperfusion Injury

INTRODUCTION

Renal ischemia and reperfusion (IR) injury introduces cellular stress and is the main cause of acute kidney damage. Renal cells exposed to noxious stress induce the expression of the pleiotropic hormone leptin. As we have previously revealed a deleterious stress-related role for leptin expression, these results suggested that leptin is also involved in pathological renal remodeling. The systemic functions of leptin preclude the study of its local effects using conventional approaches. We have therefore designed a method to locally perturb leptin activity in specific tissues without affecting its systemic levels. This study explores whether local anti-leptin strategy is renoprotective in a post-IR porcine kidney model.

METHODS

We induced renal IR injury in pigs by exposing kidneys to ischemia and revascularization. Upon reperfusion, kidneys instantly received an intra-arterial bolus of either a leptin antagonist (LepA) or saline solution. Peripheral blood was sampled to assess systemic leptin, IL-6, creatinine, and BUN levels, and postoperative tissue samples were analyzed by hematoxylin and eosin histochemistry and immunohistochemistry.

RESULTS

Histology of IR/saline kidneys exhibited extensive necrosis of proximal tubular epithelial cells, as well as elevated levels of apoptosis markers and inflammation. In contrast, IR/LepA kidneys showed no signs of necrosis or inflammation with normal IL-6 and tall-like receptor 4 levels. LepA treatment led to upregulation in mRNA levels of leptin, leptin receptor, ERK1/2, STAT3, and transport molecule Na/H exchanger-3.

CONCLUSIONS

Local, intrarenal postischemic LepA treatment at reperfusion prevented apoptosis and inflammation and was renoprotective. Selective intrarenal administration of LepA at reperfusion may provide a viable option for clinical implementation.

Detrimental Effect of Sitagliptin Induced Autophagy on Multiterritory Perforator Flap Survival

Multiterritory perforator flap survival is commonly applied in surgical tissue reconstructions and covering of large skin defects. However, multiple risk factors such as ischemia, reperfusion injury, and apoptosis after reconstructive surgeries cause necrosis in distal parts with outcomes ranging from poor aesthetic appearance to reconstructive failure. A few studies have reported that sitagliptin (Sit) promotes angiogenesis and inhibits apoptosis. However, little is known about Sit-induced autophagy especially on the flap model. Therefore, our study investigated the effect of Sit and its induced autophagy on the perforator flap survival. Ninety male Sprague-Dawley rats were randomly separated into control, Sit, and Sit+3-methyladenine group. Results revealed that Sit significantly promoted flap survival by enhancing angiogenesis, reducing oxidative stress, and attenuating apoptosis. In addition, flap survival was further improved after co-administration with 3-methyladenine to inhibit autophagy. Overall, our results established that Sit has positive effects in promoting survival of multiterritory perforator flap. Sit-induced autophagy was detrimental for flap survival and its inhibition may further improve flap survival.

Betulinic Acid Enhances the Viability of Random-Pattern Skin Flaps by Activating Autophagy

Random-pattern skin flap replantation is commonly used to repair skin defects during plastic and reconstructive surgery. However, flap necrosis due to ischemia and ischemia-reperfusion injury limits clinical applications. Betulinic acid, a plant-derived pentacyclic triterpene, may facilitate flap survival. In the present study, the effects of betulinic acid on flap survival and the underlying mechanisms were assessed. Fifty-four mice with a dorsal random flap model were randomly divided into the control, betulinic acid group, and the betulinic acid + 3-methyladenine group. These groups were treated with dimethyl sulfoxide, betulinic acid, and betulinic acid plus 3-methyladenine, respectively. Flap tissues were acquired on postoperative day 7 to assess angiogenesis, apoptosis, oxidative stress, and autophagy. Betulinic acid promoted survival of the skin flap area, reduced tissue edema, and enhanced the number of microvessels. It also enhanced angiogenesis, attenuated apoptosis, alleviated oxidative stress, and activated autophagy. However, its effects on flap viability and angiogenesis, apoptosis, and oxidative stress were reversed by the autophagy inhibitor 3-methyladenine. Our findings reveal that betulinic acid improves survival of random-pattern skin flaps by promoting angiogenesis, dampening apoptosis, and alleviating oxidative stress, which mediates activation of autophagy.

Effects of bradykinin on the survival of multiterritory perforator flaps in rats

Background

Bradykinin, a vasoactive peptide, has many biological functions. For example, it accelerates angiogenesis. Thus, we studied the effects of bradykinin on the survival of perforator flaps.

Methods

Averagely, 50 male Sprague–Dawley rats were divided into control and bradykinin groups and underwent procedures to the multiterritory perforator flap. Areas of flap survival were tested 7 days later. Flap perfusion was evaluated by laser Doppler imaging. We assessed the extent of autophagy by determining LC3-II/I, Beclin 1, and p62. Flap angiogenesis was assessed by immunohistochemistry and H&E staining. We measured the level of vascular endothelial growth factor (VEGF) protein using western blot. We assessed oxidative stress by measuring the activity of superoxide dismutase (SOD) and malondialdehyde (MDA) levels. The apoptotic index was also evaluated by western blot, and we determined nitric oxide (NO) production using an NO assay kit.

Results

The bradykinin group exhibited significantly larger areas of flap survival, higher blood supply, and more neovascularization. The bradykinin group also had higher SOD activity, higher VEGF expression and NO content, and reduced MDA compared to the control group. Rats treated with bradykinin also had lower levels of apoptosis and autophagy relative to the control group.

Conclusion

Our results suggest that bradykinin promotes the survival of multiterritory perforator flaps by increasing angiogenesis, promoting the release of NO, suppressing apoptosis, reducing oxidative stress, and inhibiting autophagy.

Comments and hypotheses on the mechanism of methane against ischemia/reperfusion injury

As we all know, methane is a kind of fuel. Previous studies have shown that methanogens in the colon can react with carbon dioxide and hydrogen to produce methane. In a recent study, the anti-inflammatory effects of methane were shown in a dog model of small intestinal ischemia/reperfusion. The mechanism of this anti-inflammatory effect needs further investigation. Recently, studies have shown anti-inflammatory, anti-apoptotic and anti-oxidative effects of methane on different organic injuries. According to the results of these studies, we hypothesize that the initial effects of methane are to react with free radicals and enhance expression of antioxidase through forkhead box transcription factor class O pathway. The anti-inflammatory effect is following the anti-oxidative effect, and the anti-apoptotic effect relies on anti-inflammatory and anti-oxidative effects.

Estradiol postconditioning relieves ischemia/reperfusion injury in axial skin flaps of rats, inhibits apoptosis and alters the MKP-1/ERK pathway

Previous studies have suggested that estradiol can reduce the ischemia/reperfusion (I/R) injury in skin flaps. However, the mechanism, particularly the signal pathways involved in this protective effect are not well established. In the current study, an I/R injury model was established in rats to explore the connection between estradiol protection during I/R injury and extracellular signal‑regulated kinase (ERK) signaling. Healthy male Wistar rats were divided into five groups (n=10): Control group (group I), I/R group (group II), saline group (group III), estradiol group (group IV) and inhibitor (PD‑98059) group (group V). The survival rate of the flap was compared between groups, morphological changes were observed by hematoxylin and eosin staining of sections, and terminal deoxynucleotidyl transferase dUTP nick end labeling was performed to identify apoptotic cells and determine the apoptotic index. To further investigate the mechanism, western blot analysis was performed to assess the protein level of ERK1/2, phospho‑ERK1/2, and mitogen‑activated protein kinase phosphatase 1 (MKP‑1). The results of the present study demonstrated that estradiol therapy can reduce I/R injury and decrease the apoptosis index in an axial skin flap model. The inhibitor of the ERK pathway (PD‑98059) partially abolished the effects of estradiol, which involve the phosphatase enzyme MKP‑1. Taken together, the findings of the present study indicate that estradiol may act by reducing the expression of MKP‑1, mediating the expression/activation changes of the ERK pathway and subsequently reduce the level of apoptosis and the I/R injury the axial flap. Estrogen may be used to mitigate the adverse reaction caused by ischemia‑reperfusion injury and effectively improve the survival rate and survival quality of free skin flap and improve patient prognosis.

Study on the effect of black cumin (Nigella sativa Linn.) on experimental renal ischemia-reperfusion injury in rats

PURPOSE

To evaluate the effect of Black cumin (Nigella sativa Linn.) pre-treatment on renal ischemia/reperfusion (I/R) induced injury in the rats.

METHODS

A total of 40 male Wistar rats were randomly allocated into five equal groups including Sham, I/R model and three I/R+ Black cumin (0.5, 1 and 2%)-treated groups. I/R groups' kidneys were subjected to 60 min of global ischemia at 37°C followed by 24 h of reperfusion. At the end of reperfusion period, the rats were euthanized. Superoxide dismutase, catalase and glutathione peroxidase activities as well as reduced glutathione and renal malondialdehyde contents were determined in renal tissues. Kidney function tests and histopathological examination were also performed.

RESULTS

High serum creatinine, blood urea nitrogen and uric acid as well as malondialhehyde (MDA) levels, and low antioxidant enzyme activities were observed in I/R rats compared to the sham rats. Pre-treatment with Black cumin for three weeks prior to IR operation improved renal function and reduced I/R induced renal inflammation and oxidative injury. These biochemical observations were supported by histopathological test of kidney sections.

CONCLUSION

Black cumin significantly prevented renal ischemia/reperfusion induced functional and histological injuries.

Methane-rich saline attenuates ischemia/reperfusion injury of abdominal skin flaps in rats via regulating apoptosis level

Background

In plastic surgery, skin damage induced by ischemia/reperfusion (I/R) is a multifactorial process that often occurs. Methane gas has been reported to be a new therapeutic gas for attenuating I/R injury. In this study, we assessed the effects of methane-rich saline (MRS) in regulating apoptosis on skin flap I/R injury.

Methods

Male Sprague–Dawley rats, 6–8 weeks old, were divided randomly into three groups: one sham surgery group (SH) and two surgery groups. After undergoing 6 h of I/R management of an abdominal skin flap, surgery groups were treated with physiological saline (I/R-P) or methane-rich saline (I/R-M). On the 3rd postoperative day, a laser Doppler flowmeter was used to measure flap blood supply, and hematoxylin and eosin (H&E) staining was used to observe morphological changes. TdT-mediated dUTP-X nick end labeling (TUNEL) staining was also used to observe early apoptosis and is presented as the percentage of TUNEL-positive cells. Moreover, pASK-1, pJNK, Bcl-2 and Bax were detected by immunohistochemical technology. Caspase-3 activity was also measured to evaluate the effects of MRS.

Results

Compared to the I/R-P group, the flaps in the I/R-M group presented a larger survival area and better blood perfusion with less inflammatory infiltration and cell apoptosis, a higher expression of Bcl-2, a lower expression of pASK-1, pJNK and Bax, and a lower caspase-3 activity.

Conclusion

According to the results, MRS attenuated I/R injury by regulating apoptosis and has the potential to be applied as a new therapy for improving skin flap survival.

Hydrogen-rich saline attenuates skin ischemia/reperfusion induced apoptosis via regulating Bax/Bcl-2 ratio and ASK-1/JNK pathway

INTRODUCTION

Many pathways have been reported involving the effect of hydrogen-rich saline on protecting skin flap partial necrosis induced by the inflammation of ischemia/reperfusion injury. This study focused on the influence of hydrogen-rich saline treatment on apoptosis pathway of ASK-1/JNK and Bcl-2/Bax radio in I/R injury of skin flaps.

METHODS

Adult male Sprague-Dawley rats were divided into three groups. Group 1 was sham surgery group, Group 2 and 3 were ischemia/reperfusion surgery treated with physiological saline and hydrogen-rich saline respectively. Blood perfusion of flap was measured by Laser doppler flowmeters. Hematoxylin and eosin staining was used to observe morphological changes. Early apoptosis in skin flap was observed through TUNEL staining and presented as the percentage of TUNEL-positive cells of total cells. pASK-1, pJNK, Bcl-2 and Bax were examined by immunodetection. In addition Bcl-2, Bax and caspase-3 were detected by qPCR. Caspase-3 activity was also measured.

RESULTS

Compared to the Group 2, tissues from the group 3 were observed with a high expression of Bcl-2 and a low expression of pASK-1, pJNK, and Bax, a larger survival area and a high level of blood perfusion. Hydrogen-rich saline ameliorated inflammatory infiltration and decreased cell apoptosis.

CONCLUSION

The results indicate that hydrogen-rich saline could ameliorate ischemia/reperfusion injury and improve flap survival rate by inhibiting the apoptosis factor and, at the same time, promoting the expression of anti-apoptosis factor.

Anticancer drug 2-methoxyestradiol protects against renal ischemia/reperfusion injury by reducing inflammatory cytokines expression

Background. Ischemia/reperfusion (I/R) injury is a major cause of acute renal failure and allograft dysfunction in kidney transplantation. ROS/inflammatory cytokines are involved in I/R injury. 2-Methoxyestradiol (2ME2), an endogenous metabolite of estradiol, inhibits inflammatory cytokine expression and is an antiangiogenic and antitumor agent. We investigated the inhibitory effect of 2ME2 on renal I/R injury and possible molecular actions. Methods. BALB/c mice were intraperitoneally injected with 2ME2 (10 or 20 mg/kg) or vehicle 12 h before and immediately after renal I/R experiments. The kidney weight, renal function, tubular damages, and apoptotic response were examined 24 h after I/R injury. The expression of mRNA of interleukin-1β, tumor necrosis factor- (TNF) α, caspase-3, hypoxia inducible factor- (HIF) 1α, and proapoptotic Bcl-2/adenovirus E1B 19 kDa interacting protein 3 (BNIP3) in kidney tissue was determined using RT-PCR, while the expression of nuclear factor κB (NF-κB), BCL-2, and BCL-xL, activated caspase-9, and HIF-1α was determined using immunoblotting. In vitro, we determined the effect of 2ME2 on reactive oxygen species (ROS) production and cell viability in antimycin-A-treated renal mesangial (RMC) and tubular (NRK52E) cells. Results. Serum creatinine and blood urea nitrogen were significantly higher in mice with renal I/R injury than in sham control and in I/R+2ME2-treated mice. Survival in I/R+2ME2-treated mice was higher than in I/R mice. Histological examination showed that 2ME2 attenuated tubular damage in I/R mice, which was associated with lower expression TNF-α, IL-1β, caspase-9, HIF-1α, and BNIP3 mRNA in kidney tissue. Western blotting showed that 2ME2 treatment substantially decreased the expression of activated caspase-9, NF-κB, and HIF-1α but increased the antiapoptotic proteins BCL-2 and BCL-xL in kidney of I/R injury. In vitro, 2MR2 decreased ROS production and increased cell viability in antimycin-A-treated RMC and NRK52E cells. Conclusions. 2ME2 reduces renal I/R injury in mice because it inhibits the expression of ROS and proinflammatory cytokines and induces antiapoptotic proteins.

Effect of a novel nuclear factor-κB activation inhibitor on renal ischemia-reperfusion injury

BACKGROUND

In kidney transplantation, the relationship between prolonged warm or cold ischemic storage of kidneys and a higher incidence of delayed graft function is previously known, and delayed graft function has been known to aggravate poor long-term graft survival. We investigated the effect of a novel nuclear factor-κB activation inhibitor, dehydroxymethylepoxyquinomicin (DHMEQ), on renal ischemia-reperfusion (I/R) injury.

METHODS

DHMEQ was administered to Lewis rats once just before renal artery clamping (DHMEQ pretreatment group), and the effect on I/R injury was investigated.

RESULTS

In the DHMEQ pretreatment group, the 24-hr urine volume on days 1 to 3 after I/R was significantly larger, and the protein concentration of the urine on days 2 to 7 was significantly smaller than in the untreated group. The serum creatinine level was significantly improved, and significantly lower levels of the inflammatory cells and inflammatory cytokines were present in the kidneys on day 1. The relative ratio of nuclear to cytoplasmic nuclear factor-κB and oxidative stress of kidney tissue on day 1 were significantly decreased.

CONCLUSIONS

Treatment with DHMEQ before renal artery clamping may therefore be useful for renal I/R injury and application to renal transplantation is expected.

An experimental rat model of ex vivo lung perfusion for the assessment of lungs regarding histopathological findings and apoptosis: low-potassium dextran vs. histidine-tryptophan-ketoglutarate

OBJECTIVE

To compare histopathological findings and the degree of apoptosis among rat lungs preserved with low-potassium dextran (LPD) solution, histidine-tryptophan-ketoglutarate (HTK) solution, or normal saline (NS) at two ischemia periods (6 h and 12 h) using an experimental rat model of ex vivo lung perfusion.

METHODS

Sixty Wistar rats were anesthetized, randomized, and submitted to antegrade perfusion via pulmonary artery with one of the preservation solutions. Following en bloc extraction, the heart-lung blocks were preserved for 6 h or 12 h at 4 ºC and then reperfused with homologous blood for 60 min in an ex vivo lung perfusion system. At the end of the reperfusion, fragments of the middle lobe were extracted and processed for histopathological examination. The parameters evaluated were congestion, alveolar edema, alveolar hemorrhage, inflammatory infiltrate, and interstitial infiltrate. The degree of apoptosis was assessed using the TdT-mediated dUTP nick end labeling method.

RESULTS

The histopathological examination showed that all of the lungs preserved with NS presented alveolar edema after 12 h of ischemia. There were no statistically significant differences among the groups in terms of the degree of apoptosis.

CONCLUSIONS

In this study, the histopathological and apoptosis findings were similar with the use of either LPD or HTK solutions, whereas the occurrence of edema was significantly more common with the use of NS.

Role of warm ischemia on innate and adaptive responses in a preclinical renal auto-transplanted porcine model

Background

Deceased after cardiac arrest donor are an additional source of kidney graft to overcome graft shortage. Deciphering the respective role of renal warm and cold ischemia is of pivotal interest in the transplantation process.

Methods

Using a preclinical pig model of renal auto-transplantation, we investigated the consequences of warm and cold ischemia on early innate and adaptive responses as well as graft outcome. Kidneys were subjected to either 60 min-warm ischemia (WI) or auto-transplanted after cold storage for 24 h at 4°C (CS), or both conditions combined (WI + CS). Renal function, immune response and cytokine expression, oxidative stress and cell death were investigated at 3 h, 3 and 7 days (H3, D3 and D7) after reperfusion. At 3 months, we focused on cell infiltration and tissue remodelling.

Results

WI + CS induced a delayed graft function linked to higher tubular damage. Innate response occurred at D3 associated to a pro-oxidative milieu with a level dependent on the severity of ischemic injury whereas adaptive immune response occurred only at D7 mainly due to CS injuries and aggravated by WI. Graft cellular death was an early event detected at H3 and seems to be one of the first ischemia reperfusion injuries. These early injuries affect graft outcome on renal function, cells infiltration and fibrosis development.

Conclusions

The results indicate that the severe ischemic insult found in kidneys from deceased after cardiac arrest donor affects kidney outcome and promotes an uncontrolled deleterious innate and adaptive response not inhibited 3 months after reperfusion.

Prevention of acute kidney injury by tauroursodeoxycholic acid in rat and cell culture models

BACKGROUND

Acute kidney injury (AKI) has grave short- and long-term consequences. Often the onset of AKI is predictable, such as following surgery that compromises blood flow to the kidney. Even in such situations, present therapies cannot prevent AKI. As apoptosis is a major form of cell death following AKI, we determined the efficacy and mechanisms of action of tauroursodeoxycholic acid (TUDCA), a molecule with potent anti-apoptotic and pro-survival properties, in prevention of AKI in rat and cell culture models. TUDCA is particularly attractive from a translational standpoint, as it has a proven safety record in animals and humans.

METHODOLOGY/PRINCIPAL FINDINGS

We chose an ischemia-reperfusion model in rats to simulate AKI in native kidneys, and a human kidney cell culture model to simulate AKI associated with cryopreservation in transplanted kidneys. TUDCA significantly ameliorated AKI in the test models due to inhibition of the mitochondrial pathway of apoptosis and upregulation of survival pathways.

CONCLUSIONS

This study sets the stage for testing TUDCA in future clinical trials for prevention of AKI, an area that needs urgent attention due to lack of effective therapies.

Role of carbon monoxide in kidney function: is a little carbon monoxide good for the kidney?

Carbon monoxide (CO) is an endogenously produced gas resulting from the degradation of heme by heme oxygense or from fatty acid oxidation. Heme oxygenase (HO) enzymes are constitutively expressed in the kidney (HO-2) and HO-1 is induced in the kidney in response to several physiological and pathological stimuli. While the beneficial actions of HO in the kidney have been recognized for some time, the important role of CO in mediating these effects has not been fully examined. Recent studies using CO inhalation therapy and carbon monoxide releasing molecules (CORMs) have demonstrated that increases in CO alone can be beneficial to the kidney in several forms of acute renal injury by limiting oxidative injury, decreasing cell apoptosis, and promoting cell survival pathways. Renal CO is also emerging as a major regulator of renal vascular and tubular function acting to protect the renal vasculature against excessive vasoconstriction and to promote natriuresis by limiting sodium reabsorption in tubule cells. Within this review, recent studies on the physiological actions of CO in the kidney will be explored as well as the potential therapeutic avenues that are being developed targeting CO in the kidney which may be beneficial in diseases such as acute renal failure and hypertension.

Effect of DHA+EPA on oxidative stress and apoptosis induced by ischemia-reperfusion in rat kidneys

Apoptosis, as well as necrosis, has an important role in post-ischemic renal pathology. The effect of pretreatment with Docosahexaenoic acid+Eicosapentaenoic acid (DHA+EPA) on renal injury and apoptotic protein expression was evaluated. Right nephrectomy was completed on male Wistar rats (255-300 g). The rats received DHA+EPA (200 mg/kg/day) of distilled water orally for 14 days before ischemia reperfusion (IR) or sham operation. A total of 81 rats were divided into three main groups with 6, 24 and 48 h of post-operation or reperfusion period. Serum creatinine (SCr), BUN, creatinine clearance (CCr) and fractional excretion of sodium (FEN a ) were measured. Tissue levels of malondialdehyde (MDA), superoxide dismutase (SOD) and catalase (CAT) activities, Bax and Bcl-2 protein expressions and renal histological injury were determined. SCr, BUN and FEN a increased 6-48 h of reperfusion (P < 0.01). Tissue MDA content and Bax expression increased (P < 0.01) and CAT and SOD activities decreased (P < 0.05) in the IR group. DHA+EPA decreased SCr and BUN, FEN a , tissue MDA levels (P < 0.05 vs. IR) and increased CAT and SOD activities and Bcl-2 expression (P < 0.05 vs. IR) for 6-48 h after ischemia. IR induced mild (6 h, P < 0.05) and severe (24-48 h, P < 0.01) tissue damage. Mild-to-moderate tissue damage was observed in DHA+EPA groups from 6 to 48 h of reperfusion period (P < 0.05 vs. IR, 24-48 h). In conclusion, the results suggest that pre-ischemic exposure to DHA+EPA could improve the outcome of early graft function by inhibition of IR-induced oxidative stress and apoptosis.

Monitoring molecular changes induced by ischemia/reperfusion in human free muscle flap tissue samples

BACKGROUND

Our current knowledge of the pathophysiological sequelae of ischemia or reperfusion (I/R) injury in free tissue transfer in reconstructive surgery is based on data obtained in animal experiments. In this study, we investigated the histologic and molecular changes after 11 free microsurgical muscle transfers in human muscle tissue.

METHODS

Biopsies of free muscle flap tissue were taken immediately before clipping of the pedicle and 5 days after ischemia and successful microanastomosis and restoration of the blood flow. Samples were analyzed histologically for edema formation and by immunohistochemistry for infiltration of inflammatory cells and angiogenesis. Expression levels of the inflammatory marker proteins interleukin-1β and tumor necrosis factor α and of complement component 3 as a major mediator of I/R injury were analyzed by real-time polymerase chain reaction. A TUNEL (terminal desoxynucleotidyl transferase-mediated-dUTP-nick-end-labeling) assay was used to assess apoptosis levels within the human muscle tissue.

RESULTS

I/R injury leads to a significant up-regulation of inflammatory parameters, infiltration of inflammatory cells, and angiogenesis. Increased complement component 3 deposition and apoptosis of cells were accompanied by interstitial edema as indication for a pronounced postischemic inflammatory reaction within the muscle tissue after free tissue transfer.

CONCLUSIONS

Our findings of molecular changes induced by I/R injury in human striated muscle tissue validate data obtained in animal models of I/R injury. The parameters and inflammatory patterns defined in this study will allow for the monitoring of the success of novel pharmaceutical strategies in the future and will help to transfer data obtained in animal work to the in vivo setting in human beings.

Protective effect of Salvia miltiorrhiza extract against renal ischemia-reperfusion-induced injury in rats

The present study investigates the effect of pre-treatment with Salvia miltiorrhiza ethanol extracts (SMEE) on renal function markers, immunity and antioxidant activities in renal ischemia and reperfusion (IR) rats. Wistar rat kidneys were subjected to 60 min of global ischemia at 37 °C followed by 30 min of reperfusion, and were randomly assigned into the sham, IR model and three SMEE-treated groups (n = 8 per group). Results showed that high serum creatinin (Scr), blood urea nitrogen (BUN), interleukin-6 (IL-6), interleukin-8 (IL-8), tumor necrosis factor-alpha (TNF-α) and malondialhehyde (MDA) levels, and low antioxidant enzyme activities were observed in IR rats compared to the sham rats. Pre-treatment of Salvia miltiorrhiza ethanol extracts for 20 days prior to IR operation improved renal function, reduced IR induced renal inflammatory and oxidative injury. It is concluded that Salvia miltiorrhiza ethanol extracts could be beneficial in the treatment of renal ischemic injury.

Negative pressure wound therapy reduces the ischaemia/reperfusion-associated inflammatory response in free muscle flaps

BACKGROUND

We recently established negative pressure wound therapy (NPWT) as a safe postoperative care concept for free muscle flaps; however, the molecular effects of NPWT on free muscle flaps remain elusive. Here we investigated the effects of NPWT on pathological changes associated with ischaemia/reperfusion injury in free flap tissue.

METHODS

From July 2008 to September 2010, 30 patients receiving skin-grafted free muscle transfer for defect coverage were randomly assigned to two treatment groups: In one group the skin-grafted free flap was covered by a vacuum dressing (NPWT); in the second group, flaps were covered by conventional petroleum gauze dressings (conv). Biopsies were taken intra-operatively prior to clipping of the pedicle and on postoperative day 5. Samples were analysed by immunohistochemistry for infiltration of inflammatory cells, real-time polymerase chain reaction (RT-PCR) for the analysis of expression levels of interleukin-1β (IL-1β) and tumour necrosis factor (TNF)-alpha as markers of inflammation. Histological samples were also examined for interstitial oedema formation, and apoptosis was detected by a terminal deoxynucleotidyl transferase dUTP nick end labelling (TUNEL) assay.

RESULTS

NPWT leads to a significantly reduced tissue infiltration of CD68 + macrophages and reduced expression of the inflammatory cytokines IL-1β and TNFα. None of these parameters was significantly elevated in the pre-ischaemic biopsies. Furthermore, NPWT reduced the interstitial oedema formation and the number of apoptotic cells in free flap tissue.

CONCLUSION

NPWT of skin-grafted free muscle flaps leads to a reduced inflammatory response following ischaemia/reperfusion, resulting in reduced oedema formation improving the microcirculation and ultimately reduced tissue damage. We thereby deliver new insight into the effects of NPWT.

Affirmative effects of iloprost on apoptosis during ischemia-reperfusion injury in kidney as a distant organ

OBJECTIVE

Apoptosis and its regulatory mechanisms take part in renal ischemia-reperfusion (I/R) injury which can result in acute renal failure and the inhibition of the caspase is considered as a new therapeutic strategy. In this context, we investigated the antiapoptotic and cytoprotective effects of iloprost, a prostacyclin analog, in kidney as a distant organ.

METHODS

Wistar albino rats were randomized into five groups (n = 12 in each) as sham, ischemia, I/R, iloprost (10 μg kg(-1)), and I/R + iloprost (10 μg kg(-1)). A 4 h reperfusion procedure was carried out after 4 h of ischemia. Caspase-8 was evaluated for death receptor-induced pathways, whereas caspase-9 was evaluated for mitochondria-dependent pathways and caspase-3 was investigated for overall apoptosis. Superoxide dismutase (SOD) enzyme activity and nitrite content as an indicator of nitric oxide (NO) production were also analyzed in kidney tissues.

RESULTS

Caspases-3, -8, and -9 were all significantly elevated in both ischemia and I/R groups compared to the sham group; however, treatment with iloprost reduced caspases-3, -8, and -9. SOD enzyme activity was attenuated by iloprost when compared to ischemic rats. The different effects of NO were found which change according to the present situation in ischemia, I/R, and treatment with iloprost.

CONCLUSIONS

These findings suggested that iloprost prevents apoptosis in both receptor-induced and mitochondria-dependent pathways in renal I/R injury and it may be considered as a cytoprotective agent for apoptosis. Understanding the efficiency of iloprost on the pathways for cell death may lead to an opportunity in the therapeutic approach for renal I/R injury.

Protective effects of Radix Codonopsis on ischemia-reperfusion injury in rats after kidney transplantation

PURPOSE

Kidney ischemia-reperfusion injury (IRI) after kidney transplant remains a major problem, separate from immune rejection that can lead to kidney transplant failure and graft function loss. Free radicals, disturbance of microcirculation and the inflammatory cascade appear to be the main contributors. Radix Codonopsis, a traditional Chinese drug used in vascular diseases, is an antioxidant and free radical scavenger. This study investigates the protective effect and underlying mechanisms of Radix Codonopsis extract saponins on kidney transplantation.

METHODS

Renal transplantation was performed after rat kidneys had been stored for 1 h at 4°C. Blood urea nitrogen (BUN), serum creatinine (Scr), superoxide dismutase (SOD) and malondialdehyde (MDA) were assayed; bcl-2 and bax mRNA expression was detected using RT-PCR; bcl-2 and bax protein expression was detected by immunohistochemistry (IHC). Terminal deoxynucleotidyl transferase biotin-dUTP nick end labeling (TUNEL) was used to detect apoptotic cells and determine the apoptosis index (AI). Analysis of variance (ANOVA) followed by Dunnett's test was used when more than two groups were compared.

RESULTS

Saponin-treated animals showed increased SOD levels accompanied by decreased MDA, Scr and BUN levels (p < 0.05 vs. untreated controls); bcl-2 mRNA and protein levels were increased in transplanted kidney from treated animals, while bax mRNA and protein levels were decreased (p < 0.05 vs. untreated controls). AI was significantly decreased in transplanted kidneys from treated animals relative to untreated controls (p < 0.05 vs. untreated controls).

CONCLUSION

This study clearly demonstrates the protective effects on IRI after kidney transplantation, which may be explained by decreased lipid peroxidation and inhibition of apoptosis.

Synchronized turbo apoptosis induced by cold-shock

In our research on the role of apoptosis in the pathogenesis of the autoimmune disease systemic lupus erythematosus (SLE), we aim to evaluate the effects of early and late apoptotic cells and blebs on antigen presenting cells. This requires the in vitro generation of sufficiently large and homogeneous populations of early and late apoptotic cells. Here, we present a quick method encountered by serendipity that results in highly reproducible synchronized homogeneous apoptotic cell populations. In brief, granulocytic 32Dcl3 cells are incubated on ice for 2 h and subsequently rewarmed at 37°C. After 30–90 min at 37°C more than 80–90% of the cells become early apoptotic (Annexin V positive/propidium iodide negative). After 24 h of rewarming at 37°C 98% of the cells were late apoptotic (secondary necrotic; Annexin V positive/propidium iodide positive). Cells already formed apoptotic blebs at their cell surface after approximately 20 min at 37°C. Inter-nucleosomal chromatin cleavage and caspase activation were other characteristics of this cold-shock-induced process of apoptosis. Consequently, apoptosis could be inhibited by a caspase inhibitor. Finally, SLE-derived anti-chromatin autoantibodies showed a high affinity for apoptotic blebs generated by cold-shock. Overall, cold-shock induced apoptosis is achieved without the addition of toxic compounds or antibodies, and quickly leads to synchronized homogeneous apoptotic cell populations, which can be applied for various research questions addressing apoptosis.

Structural features and bioactivities of the chitosan

Fourier transform infrared (FT-IR) spectroscopic studies (3500-600 cm(-1)) showed some different bands of chitosan. The absorption at 3439 cm(-1) is stretching vibration of -OH and -NH(2) bonds, indicating the association of the hydrogen-bond between them. The bands at 1659, 1599 and 1321 cm(-1) are attributable to the peaks of stretching vibrations of amide I (ν((C=O))), II (δ((N-H))), and the peak of stretching and bending vibrations of III (ν((C-N))) (δ((N-H))). The chitosan showed strong free radical scavenging activities. Pretreatment with chitosan significantly prevented the decrease of antioxidant enzymes activities and the increase of p-JNK at 3 h after renal ischemia and reduced renal tubular epithelial cell apoptosis.

Tubular epithelial injury and inflammation after ischemia and reperfusion in human kidney transplantation

OBJECTIVE

To provide an integrated insight into the kinetics of tubular injury, inflammation, and oxidative stress after human kidney transplantation.

BACKGROUND

Tissue injury due to ischemia and reperfusion is an inevitable consequence of kidney transplantation. Tubular epithelial injury, inflammation, and oxidative stress play major roles in the pathophysiology of acute kidney injury in small animals, but it remains to be established whether this paradigm holds true for human kidney transplantation.

METHODS

Markers of tubular injury, inflammation, and oxidative stress were compared between recipients of kidneys from donors after cardiac death (DCD; N = 8) with prolonged ischemia and recipients of living donor kidneys with minimal ischemia (N = 8).

RESULTS

In the early postoperative period, creatinine clearance and tubular sodium reabsorption were profoundly reduced in DCD kidneys, coinciding with significantly increased urinary concentrations of tubular injury markers (neutrophil gelatinase-associated lipocalin, N-acetyl-β--glucosaminidase, and cystatin C) and an 18-fold increase in renal production of cytokeratin-18, indicating extensive necrotic cell death. Tubular injury in DCD kidneys was followed by greater systemic inflammatory activity and oxidative stress in the postoperative period (measured with 17-plex cytokine arrays and as plasma F2-isoprostanes, respectively). In contrast, no evidence of oxidative damage to either of the 2 kidney types was found in the early reperfusion period.

CONCLUSIONS

These findings establish the relevance of observations in animal models for human kidney transplantation and form the basis for development of novel therapies to improve early graft function and expand the use of donor kidneys with prolonged ischemia.

Protective effect of Lifor solution in experimental renal ischemia-reperfusion injury

BACKGROUND

Improved kidney preservation methods are needed to reduce ischemia-reperfusion (IR) injury in kidney allografts. Lifor is an artificial preservation solution comprised of nutrients, growth factors, and a non-protein oxygen and nutrient carrier. The current study compared the effectiveness of Lifor to University of Wisconsin solution (UW) in protecting rat kidneys from warm IR and cold storage injury.

MATERIALS AND METHODS

In a warm IR model, rat kidneys were perfused in situ with either saline, UW, or Lifor for 45 min. Renal function and histology were assessed 24 h later. In a cold IR model, kidney slices were cold-stored in saline, UW, or Lifor at 4°C. Kidney injury was assessed by the release of lactate dehydrogenase (LDH) and immunoblot analysis for cleaved caspase-3.

RESULTS

Lifor perfusion significantly mitigated renal dysfunction and tubular injury at 24 h compared with saline or UW. Lifor and UW prevented LDH release in hypoxic kidney slices in vitro, however activation of caspase-3 following hypoxia-reoxygenation was attenuated only with Lifor. Cold storage with Lifor or UW significantly decreased LDH release from kidney slices or normal rat kidney cells in comparison to storage in saline or culture media. After 24 h of cold storage there was a significant decrease in cleaved caspase-3 in Lifor stored slices compared that seen following cold storage in saline or UW solution.

CONCLUSIONS

Lifor solution mitigates both warm and cold renal IR and appears to provide greater protection from apoptosis compared with UW solution.

Biological modulation of renal ischemia-reperfusion injury

PURPOSE OF REVIEW

Biological modulation of renal ischemia-reperfusion injury holds the potential to reduce the incidence of early graft dysfunction and to safely expand the donor pool with kidneys that have suffered prolonged ischemic injury before organ recovery.

RECENT FINDINGS

In the current review, we will discuss clinical studies that compare kidney transplant recipients with and without early graft dysfunction in order to elucidate the pathophysiology of ischemic acute allograft injury. We will specifically review the mechanisms leading to depression of the glomerular filtration rate and activation of the innate immune system in response to tissue injury.

SUMMARY

We conclude that the pathophysiology of delayed graft function after kidney transplantation is complex and shares broad similarity with rodent models of ischemic acute kidney injury. Given the lack of specific therapies to prevent delayed graft function in transplant recipients, comprehensive efforts should be initiated to translate the promising findings obtained in small animal models into clinical interventions that attenuate ischemic acute kidney injury after transplantation.

Cytoprotective Actions of FTY720 Modulate Severe Preservation Reperfusion Injury in Rat Renal Transplants

BACKGROUND

Fingolimod (FTY720) is a potent agonist of sphingosine 1 phosphate receptors and thereby interferes with lymphocyte trafficking. We previously showed that FTY720 protects from mild preservation reperfusion injury induced by 4 hr of cold ischemia. The purpose of this study was to explore the role of FTY720 in ischemic injury and regeneration using a clinically relevant rat renal transplant model with 24 hr of cold ischemia.

METHODS

Donor kidneys were cold stored in the University of Wisconsin solution for 24 hr before transplantation into bilaterally nephrectomized syngeneic recipients (n=6 per group), which received 0.5 mg/kg/d FTY720 or vehicle through oral gavage. Grafts were harvested 2 or 7 days posttransplantation. Renal tissue was examined histologically, stained for apoptosis, proliferation, inflammatory cell infiltrates, and studied for transforming growth factor-beta, and tumor necrosis factor-alpha expression. Rat proximal tubular cells were incubated with 0.1 to 30 micromol/L of phosphorylated FTY720 to test for in vitro cytopathic effects.

RESULTS

FTY720 induced peripheral lymphopenia and significantly reduced intragraft CD3 and ED1 infiltrates. Acute tubular damage scores and graft function were not influenced by FTY720. Tubular apoptosis was significantly reduced, whereas the number of proliferating cell nuclear antigen-positive tubular cells were markedly increased. FTY720 attenuated renal tumor necrosis factor-alpha and transforming growth factor-beta expression. In vitro, pharmacologic concentrations up to 1 micromol/L of phosphorylated FTY720 did not affect tubular cell viability.

CONCLUSION

FTY720 confers tubular epithelial protection in the presence of severe preservation reperfusion injury. Beneficial effects may in part be due to reduction in cell-mediated immune mechanisms. Furthermore, FTY720 could be helpful in patients with delayed graft function.

Hydrogen sulphide ameliorates ischaemia-reperfusion injury in an experimental model of non-heart-beating donor kidney transplantation

BACKGROUND

: Therapies to alleviate ischaemia-reperfusion (IR) injury have an important role in kidney transplantation. This study used a porcine model of non-heart-beating (NHB) donor kidneys to investigate the effects of hydrogen sulphide on IR injury.

METHODS

: Porcine kidneys were subjected to 25 min of warm ischaemia and 18 h of cold storage. They were reperfused ex vivo with autologous oxygenated blood to assess renal function. A group treated with hydrogen sulphide (0.5 mmol/l) infused 10 min before and after reperfusion (n = 6) was compared with an untreated control group (n = 7).

RESULTS

: Hydrogen sulphide significantly improved renal blood flow compared with control values (mean(s.d.) area under the curve (AUC) 614.9(165.5) versus 270.3(86.7) ml per min per 100 g.h; P = 0.001) and renal function (AUC creatinine: 1640(248) versus 2328(154) micromol/l.h; P = 0.001; AUC creatinine clearance: 6.94(5.03) versus 0.96(0.32) ml per min per 100 g.h; P = 0.004). Oxidative damage was also reduced by hydrogen sulphide (urinary 8-isoprostane at 1 h of reperfusion: 478.9(237.1) versus 1605.6(632.7) pg/ml per mmol/l creatinine; P = 0.032).

CONCLUSION

: Hydrogen sulphide ameliorated the renal dysfunction associated with ischaemic damage, and has potential as a therapy against IR injury in NHB donor kidney transplantation.

Nitro-oleic acid protects the mouse kidney from ischemia and reperfusion injury

Nitroalkene derivatives of linoleic acid (nitrolinoleic acid; LNO2) and nitro-oleic acid (OA-NO2) are endogenous lipid products with potent anti-inflammatory properties. The present study was undertaken to evaluate the therapeutic potential of OA-NO2 in a mouse model of renal ischemia-reperfusion (I/R) injury. B6129SF2/J mice were subjected to bilateral renal ischemia for 30 min, followed by 24 h of reperfusion. Fifty minutes after ischemia, mice received intraperitoneal (ip) injections of OA-NO2 (500 microg/kg; I/R OA-NO2), vehicle for OA-NO2 (i.e., 0.8 ml/kg ethanol; I/R veh), or oleic acid (500 microg/kg; I/R OA) every 6 h during the 24-h recovery period. A sham-operated group was not subjected to ischemia and received 0.8 ml/kg ethanol ip every 6 h during the 24-h recovery period (sham veh). While plasma urea and creatinine were elevated (P<0.05) in I/R veh vs. sham veh mice, the severity was less (P<0.05) in I/R OA-NO2 animals. Indices of histological damage, polymorphonucleocyte infiltration, together with expression of intracellular adhesion molecule-1, interleukin-1beta, and tumor necrosis factor-alpha, p47(phox), and gp91(phox) were greater in I/R veh vs. sham veh mice, but were attenuated (P<0.05) in I/R OA-NO2 animals. Because indices of renal dysfunction were similar between I/R veh and I/R OA mice (P>0.05), but less (P<0.05) in I/R OA-NO2 animals compared with both groups, protection from bilateral renal ischemia is afforded by the nitrated but not free form of oleic acid. Together, delayed administration of nitrated fatty acid OA-NO2 attenuates renal I/R injury in the mouse likely via inhibition of the inflammatory response.

Association of donor inflammation- and apoptosis-related genotypes and delayed allograft function after kidney transplantation

BACKGROUND

Delayed renal allograft survival (delayed graft function [DGF]) after deceased donor kidney transplantation is associated with an increased risk of allograft loss. Inflammatory response and apoptosis are associated with increased risk of DGF.

STUDY DESIGN

Cross-sectional study.

SETTING & PARTICIPANTS

We first recruited 616 recipients of kidneys from 512 deceased kidney donors, and donor DNA was genotyped. These recipients, who were included in a prospective cohort study of 9 transplant centers in the Delaware Valley region, had their DGF outcome obtained through medical record abstraction. We then identified the recipient (n = 349) of the contralateral deceased kidney donor, if not part of the cohort, through the US Renal Data System registry. The final cohort consisted of 965 recipients of deceased donor kidneys from 512 donors.

PREDICTORS

Donor single-nucleotide polymorphisms in genes for tumor necrosis factor alpha (TNF), transforming growth factor beta1 (TGFB1), interleukin 10 (IL10), p53 (TP53), and heme oxygenase 1 (HMOX1).

OUTCOMES

DGF, defined as the need for dialysis therapy in the first week posttransplantation. Secondary outcomes included acute rejection and estimated glomerular filtration rate.

MEASUREMENTS

Information for DGF, acute rejection, and estimated glomerular filtration rate for recipients in the Delaware Valley Cohort was obtained through medical record abstraction. For other recipients, information for DGF was obtained from United Network for Organ Sharing forms and Centers for Medicare & Medicaid Services claims in the US Renal Data System registry.

RESULTS

No association was detected between the TGFB1, IL10, TP53, and HMOX1 genes and DGF. The G allele of the TNF polymorphism rs3093662 was associated with DGF in an adjusted analysis (odds ratio, 1.85 compared with A allele; 95% confidence interval, 1.16 to 2.96; P = 0.01). However, this association did not achieve statistical significance after adjusting for multiple comparisons.

LIMITATIONS

Inadequate sample size for infrequent genotypes and multiple comparisons.

CONCLUSION

Because of the low frequency of donor single-nucleotide polymorphisms of interest, a larger sample size and replication are necessary to confirm these findings on the association of donor genotypes with DGF.

Carbon monoxide protects against ischemia-reperfusion injury in an experimental model of controlled nonheartbeating donor kidney

BACKGROUND

CO-releasing molecule-3 (CORM-3) is a transitional metal carbonyl that liberates carbon monoxide under appropriate conditions. Carbon monoxide exerts effects on intracellular apoptotic and inflammatory pathways, which suggest a role in reducing the effects of renal ischemia/reperfusion (I/R) injury. This study investigated the effects of CORM-3 administered at the time of reperfusion in a model of controlled nonheartbeating donor kidneys.

METHODS

Porcine kidneys (n=4) were subjected to 10 min warm ischemia and 18 hr cold storage (CS) and then treated as follows: CORM-3 (50, 100, 200, and 400 microM doses), iCORM-3 (inactive carbon monoxide-releasing molecule, 50 microM), and control (no further intervention). Renal hemodynamics and function were then measured during 3-hr reperfusion with autologous blood using an isolated organ-perfusion system.

RESULTS

CORM-3 at a concentration of 50 microM improved renal blood flow (RBF) compared with the iCORM and control groups (area under the curve 774+/-19 vs. 448+/-88 vs. 325+/-70, respectively, P=0.002). CO-releasing molecule-3 at a concentration of 50 microM also improved renal function during reperfusion with a greater area under the curve for creatinine clearance (CORM-3: 14+/-6 vs. iCORM: 3.3+/-0.1 vs. control: 2.2+/-2 mL/min, P=0.006) and higher urine output (CORM-3: 793+/-212 vs. iCORM: 368+/-72 vs. control: 302+/-211 mL, P=0.01). CO-releasing molecule-3 at a concentration of 100 microM exerted similar effects. Treatment with CORM-3 at higher doses (200 and 400 microM) led to poor renal hemodynamics and function after reperfusion.

CONCLUSION

Low-dose CORM-3 significantly ameliorates the effects of ischemia/reperfusion in a porcine model of controlled nonheartbeating donor kidney transplantation.

Proteomics for biomarker discovery in acute kidney injury

Acute kidney injury (AKI), previously referred to as acute renal failure, represents a common and devastating problem in clinical medicine. Despite significant improvements in therapeutics, the mortality and morbidity associated with AKI remain high. A major reason for this is the lack of early markers for AKI, and hence an unacceptable delay in initiating therapy. Fortunately, the application of innovative technologies such as functional genomics and proteomics to human and animal models of AKI has uncovered several novel biomarkers and therapeutic targets. The most promising of these are chronicled in this review. These include the identification of biomarker panels in plasma (neutrophil gelatinase-associated lipocalin and cystatin C) and urine (neutrophil gelatinase-associated lipocalin, kidney injury molecule-1, interleukin-18, cystatin C, alpha1-microglobulin, Fetuin-A, Gro-alpha, and meprin). It is likely that the AKI panels will be useful for timing the initial insult, and assessing the duration and severity of AKI. It is also probable that the AKI panels will distinguish between the various etiologies of AKI and predict clinical outcomes. It will be important in future studies to validate the sensitivity and specificity of these biomarker panels in clinical samples from large cohorts and from multiple clinical situations. Such studies will be facilitated markedly by the development of commercial tools for the reproducible measurement of biomarkers across different laboratories.

Effects of erythropoietin on ischaemia/reperfusion injury in a controlled nonheart beating donor kidney model

Erythropoietin (EPO) has been shown to have an anti-apoptotic action and has the potential to protect against ischaemia/reperfusion injury. This study investigated the effect of high dose EPO (5000 U), administered as a bolus at the onset of reperfusion and at the onset of cold storage in a model of controlled nonheart beating donors kidneys. Porcine kidneys(n = 6) were subjected to 10min warm ischaemia and preserved as follows: Group 1:16 h Cold storage +2 h Normothermic perfusion (16 h CS + 2 h NP) Group 2:16 h CS + 2 h NP + EPO given at the onset of reperfusion Group 3:18 h CS (static hypothermic storage) Group 4:18 h CS + EPO given at the onset of cold storage Haemodynamic and functional parameters were assessed during 3-h reperfusion using autologous blood. Renal blood flow improved in Groups 1 and 2 vs. Groups 3 and 4 though no difference was noted between Groups 3 and 4 (563 +/- 119 vs. 491 +/- 95 vs. 325 +/- 70 vs. 418 +/- 112, respectively; P = 0.012). Total urine output showed no difference between Groups (271 +/- 172 vs. 359 +/- 184 vs. 302 +/- 21 vs. 421 +/- 88; P = 0.576). Percentage serum creatinine fall at 3 h was significantly better in Groups 1 and 2 vs. Group 3 (64 +/- 17 vs. 60 +/- 11 vs. 44 +/- 13 vs. 52 +/- 8; P = 0.04). Fractional-excretion of sodium was significantly lower for Groups 1 and 2 vs. Group 3 and 4 (17 +/- 14 vs. 18 +/- 9 vs. 49 +/- 21 vs. 45 +/- 16 respectively; P = 0.002). There was significant improvement in oxygen consumption in Groups 2 vs. Groups 3 and 4 (P = 0.037) (39 +/- 10 vs. 46 +/- 10 vs. 24 +/- 12 vs. 24 +/- 7 respectively). EPO added at the time of reperfusion improved oxygen consumption when added to NP in comparison to static hypothermic storage but did not exert any other major benefits.

Hepatocyte growth factor prevents pulmonary ischemia-reperfusion injury in mice

BACKGROUND

Ischemia-reperfusion (IR) injury after lung transplantation leads to significant morbidity and mortality in recipients, which remains the major obstacle in clinical lung transplantation. To reduce pulmonary graft dysfunction and improve prognosis after lung transplantation, prevention of IR-induced lung injury in the peri-operative period is required. In the present study, we investigated the effects of recombinant hepatocyte growth factor (HGF) on pulmonary IR injury using a murine model system.

METHODS

To assess the protective effect of HGF against lung injury, mice with pulmonary IR were divided into two groups and injected with 500 microg/kg of human recombinant HGF or the same dose of saline alone as a control.

RESULTS

After pulmonary IR injury, the lung injury score increased in a time-dependent manner up to 24 hours. A significant reduction of lung injury score was observed with the administration of exogenous HGF. Moreover, the ratio of apoptotic cells was significantly reduced in mice treated with HGF. Significantly increased expression of Bcl-xL was observed after IR in mice administered HGF as compared with saline-treated controls. In contrast, expression of Bax was reduced significantly in HGF-treated mice. Serum levels of endogenous murine HGF were increased significantly in HGF-treated mice.

CONCLUSIONS

Our findings indicate that administration of exogenous HGF ameliorates the pulmonary tissue injury induced by IR, which may provide an alternative for prevention of IR-induced lung injury in the peri-operative period in lung transplantation.

Novel pharmacological approaches to the treatment of renal ischemia-reperfusion injury: a comprehensive review

Renal ischemia-reperfusion (I-R) contributes to the development of ischemic acute renal failure (ARF). Multi-factorial processes are involved in the development and progression of renal I-R injury with the generation of reactive oxygen species, nitric oxide and peroxynitrite, and the decline of antioxidant protection playing major roles, leading to dysfunction, injury, and death of the cells of the kidney. Renal inflammation, involving cytokine/adhesion molecule cascades with recruitment, activation, and diapedesis of circulating leukocytes is also implicated. Clinically, renal I-R occurs in a variety of medical and surgical settings and is responsible for the development of acute tubular necrosis (a characteristic feature of ischemic ARF), e.g., in renal transplantation where I-R of the kidney directly influences graft and patient survival. The cellular mechanisms involved in the development of renal I-R injury have been targeted by several pharmacological interventions. However, although showing promise in experimental models of renal I-R injury and ischemic ARF, they have not proved successful in the clinical setting (e.g., atrial natriuretic peptide, low-dose dopamine). This review highlights recent pharmacological developments, which have shown particular promise against experimental renal I-R injury and ischemic ARF, including novel antioxidants and antioxidant enzyme mimetics, nitric oxide and nitric oxide synthase inhibitors, erythropoietin, peroxisome-proliferator-activated receptor agonists, inhibitors of poly(ADP-ribose) polymerase, carbon monoxide-releasing molecules, statins, and adenosine. Novel approaches such as recent research involving combination therapies and the potential of non-pharmacological strategies are also considered.

Protective effects of peroxisome proliferator-activated receptor gamma ligand on apoptosis and hepatocyte growth factor induction in renal ischemia-reperfusion injury

BACKGROUND

Renal ischemia-reperfusion injury affects the long-term outcome of renal graft survival. Thiazolidinediones (TZDs), synthetic peroxisome proliferator-activated receptor (PPAR)-gamma ligands, have been shown to exert therapeutic effects upon renal ischemia-reperfusion injury far beyond their use as insulin sensitizers. It has also been reported that hepatocyte growth factor (HGF) has a beneficial effect on renal ischemia-reperfusion injury and that TZDs induce increased HGF mRNA expression and protein secretion. We investigated the effect of troglitazone, one of the TZDs, in a rat model of renal ischemia-reperfusion injury.

METHODS

A 45-minute period of warm renal ischemia was induced by bilateral clamping at 37 degrees C with rats being sacrificed before the onset of ischemia and at 2, 4, 6, and 12 hr after reperfusion. The expression of PPAR-gamma was measured by reverse-transcriptase polymerase chain reaction (RT-PCR) and western blotting while the production of HGF was investigated by RT-PCR and immunohistochemistry. The effect of troglitazone treatment on the level of apoptosis was determined by staining for cleaved caspase-3 and single-stranded DNA (ssDNA).

RESULTS

The numbers of cleaved caspase-3 and ssDNA positive cells were decreased in rats treated with troglitazone. The production of HGF mRNA and protein was most intense at 4 hr. The expression of PPAR-gamma and HGF was increased in the group treated with troglitazone compared with the control group. CONCLUSIONS.: Pretreatment of rats with the PPAR-gamma ligand troglitazone decreased apoptotic cell death in renal ischemia-reperfusion injury as a result of the induction of HGF.

Reduction of ischemia-reperfusion injury in the rat kidney by FTY720, a synthetic derivative of sphingosine

BACKGROUND

The current shortage of organ donors has led many centers to use marginal and nonheart-beating donors (NHBDs). Recent research has implicated the infiltration of lymphocytes as an important mediator of ischemia-reperfusion injury (IRI). FTY720 is an immunosuppressant that promotes lymphocyte sequestration into lymph nodes. The purpose of this study was to examine the potential for FTY720 to abrogate IRI when subjected to increasing ischemic times.

METHODS

Male Sprague-Dawley rats underwent bilateral flank incision with removal of the right kidney and clamping of the left hilum. Groups were divided into ischemia times of 45, 55, and 65min; each group was further divided into a control group (IRI only), IRI+FTY720 (1 mg/kg/d), and IRI+cyclosporine (15 mg/kg/d), n=4 per group.

RESULTS

Thre days after 45 min of ischemia, serum creatinine in the ischemia only (477+/-37 micromol/L) and cyclosporine groups (698+/-32 micromol/L) was significantly increased compared with the FTY720-treated animals (194+/-66 micromol/L). The beneficial effect of FTY720 was also observed at 55 and 65 min; indeed, FTY720-treated animals demonstrated signs of recovery from 65 min of ischemia whereas control and cyclosporine-treated animals required sacrifice between days 3 and 5. Treatment with FTY720 reduced renal damage assessed histologically and also reduced apoptosis and increased cell proliferation.

CONCLUSION

Treatment with FTY720 reduced IRI and prevented unrecoverable acute renal failure after significant ischemic injury. This study suggests that FTY720 may help improve the quality of grafts from NHBD and marginal donors by abrogating the IRI insult.

Differential expression of cytoprotective and apoptotic genes in an ischaemia-reperfusion isolated organ perfusion model of the transplanted kidney

The optimal kidney preservation system and methods to ameliorate reperfusion injury are major factors in accomplishing successful graft function following transplantation. Ischaemia and reperfusion lead to cellular stress and the adaptive response may include the activation of genes involved in cellular protection and/or cell death by apoptosis. We investigated the expression of cytoprotective heme oxygenase-1 (HO-1), anti-apoptotic Bcl-2 and pro-apoptotic Bax after 6 h isolated organ perfusion in porcine kidneys that had been given 10 and 40 min warm ischaemic time. The level of HO-1 was shown to be significantly higher in the 10-min warm ischaemic group compared with 40-min group (0.90 +/- 0.03 vs. 0.83 +/- 0.03; P = 0.002). The levels of HO-1 showed a significant positive correlated with parameters of renal function, creatinine clearance, and renal blood flow and urine output (AUC; r = 0.8042, P = 0.03; r = 0.6028, P = 0.04; r = 0.6055, P = 0.04), demonstrating a possible protective role of this gene in this model of renal transplantation.

Apoptosis antagonizing transcription factor protects renal tubule cells against oxidative damage and apoptosis induced by ischemia-reperfusion

Apoptosis antagonizing transcription factor (AATF) is a leucine zipper domain-containing protein that has antiapoptotic properties. AATF is expressed in several organs and tissues, including the kidney. AATF may participate in inhibition of proapoptotic pathways and/or activation of antiapoptotic pathways. Ischemia/reperfusion-induced renal injury (IRI) is clinically important because it typically damages renal tubular epithelial cells and glomerular cells and is the most common cause of acute renal failure. It now is reported that AATF is expressed in human kidney proximal tubule (HK-2) cells and in mouse primary renal tubule epithelial cells. Levels of AATF expression were altered significantly in these cells in a well-established in vitro model of renal IRI. In transfected HK-2 cells, RNA interference-mediated silencing of AATF exacerbated whereas overexpression of the full-length AATF ameliorated mitochondrial dysfunction, accumulation of superoxide and peroxynitrite, lipid peroxidation, caspase-3 activation, and apoptotic death that were induced by IRI. In primary renal tubule epithelial cells, overexpression of AATF mediated by recombinant adeno-associated virus (AAV) vectors resulted in significant antiapoptotic activity, whereas knockdown of AATF by small interference RNA led to exacerbated cell death after IRI. These results identify AATF as a novel cytoprotective factor against oxidative and apoptotic damage in renal tubular cells. AATF may represent a potential candidate for therapeutic application in IRI.

Increasing resistance of tubular epithelial cells to apoptosis by shRNA therapy ameliorates renal ischemia-reperfusion injury

Renal tubular epithelial cells (TEC) die by apoptosis or necrosis in renal ischemia-reperfusion injury (IRI). Fas/Fas ligand-dependent fratricide is critical in TEC apoptosis, and Fas promotes renal IRI. Therefore, targeting Fas or caspase-8 may have therapeutic potential for renal injury in kidney transplant or failure. RNA silencing by short hairpin RNA (shRNA) is a novel strategy to down-regulate protein expression. Using this approach, silencing of Fas or caspase-8 by shRNA to prevent TEC apoptosis and IRI was evaluated. IRI was induced by renal artery clamping for 45 or 60 min at 32 degrees C in uninephrectomized C57BL/6 mice. Here, we showed that Fas or pro-caspase-8 expression was significantly knocked down in TEC by stable expression of shRNA, resulting in resistance to apoptosis induced by superoxide, IFN-gamma/TNF-alpha and anti-Fas antibody. Inferior vena cava delivery of pHEX-small interfering RNA targeting Fas or pro-caspase-8 resulted in protection of kidney from IRI, indicated by reduction of renal tubular injury (necrosis and apoptosis) and serum creatinine or blood urea nitrogen. Our data suggest that shRNA-based therapy targeting Fas and caspase-8 in renal cells can lead to protection of kidney from IRI. Attenuation of pro-apoptotic proteins using genetic manipulation strategies such as shRNA might represent a novel strategy to promote kidney allograft survival from rejection or failure.