Lipid peroxidation and the expressional regulation of the heat-shock response during ischemia-reperfusion of rat kidney

Ischemia postconditioning and mesenchymal stem cells engraftment synergistically attenuate ischemia reperfusion-induced lung injury in rats

BACKGROUND

It has been reported that ischemic postconditioning (IPO) or mesenchymal stem cell (MSC) engraftment could protect organs from ischemia/reperfusion (I/R) injury. We investigated the synergetic effects of combined treatment on lung injury induced by I/R.

METHODS

Adult Sprague-Dawley rats were randomly assigned to one of the following groups: sham-operated control, I/R, IPO, MSC engraftment, and IPO plus MSC engraftment. Lung injury was assessed by arterial blood gas analysis, the wet/dry lung weight ratio, superoxide dismutase level, malondialdehyde content, myeloperoxidase activity, and tissue histologic changes. Cytokine expression was detected using real-time polymerase chain reaction, Western blotting, and enzyme-linked immunosorbent assay. Cell apoptosis was determined by terminal deoxynucleotidyl transferase-mediated deoxyuridine triphosphate-biotin nick end assay and annexin V staining.

RESULTS

MSC engraftment or IPO alone markedly attenuated the lung wet/dry weight ratio, malondialdehyde and myeloperoxidase production, and lung pathologic injury and enhanced arterial partial oxygen pressure, superoxide dismutase content, inhibited pro-inflammatory cytokine levels, and decreased cell apoptosis in lung tissue, compared with the I/R group. In contrast, IPO pretreatment enhanced the protective effects of MSC on I/R-induced lung injury compared with treatment alone. Moreover, in the combined treatment group, the number of MSC engraftments in the lung tissue was increased, associated with enhanced survival of MSCs compared with MSC treatment alone. Additional investigation showed that IPO treatment increased expression of vascular endothelial growth factor and stromal cell-derived factor-1 in I/R lung tissue.

CONCLUSIONS

IPO might contribute to the homing and survival of transplanted MSCs and enhance their therapeutic effects through improvement of the microenvironment of I/R injury.

Oxypurine and purine nucleoside concentrations in renal vein of allograft are potential markers of energy status of renal tissue

BACKGROUND

Impairment of organ function derived from ischemia-reperfusion injury is an important problem in solid organ transplantation. Cell alterations induced by ischemia prime the tissue for subsequent damage that occurs during the reperfusion phase. Purine nucleosides and oxypurines are products of adenine nucleotides degradation. Reperfusion and reoxygenation are accompanied by production of reactive oxygen species and free radicals, which lead to damage of graft tissue. The aim of this study was to measure concentrations of adenine nucleotides and their metabolites in renal allograft vein as well as in recipient's peripheral veins during the reperfusion period and to evaluate their usefulness as markers of tissue metabolism in kidney allografts.

METHODS

The study enrolled 20 renal transplant recipients. The first blood sample was taken from the recipient's ulnar vein before anastomosing of the kidney graft's vessels with recipient's iliac vessels. Samples were then taken from the renal allograft and ulnar veins 5 min after total graft reperfusion measured with an infrared camera. High-performance liquid chromatography (HPLC) was performed to measure whole blood and plasma concentrations of adenosine triphosphate (ATP), adenosine monophosphate (AMP), guanosine (Guo), inosine (Ino), hypoxanthine (Hyp), xanthine (Xan), uric acid (UA), and uridine (Urd).

RESULTS

Hyp and Xan concentrations were significantly increased in renal allograft vein after reperfusion as compared with peripheral vein during the pre- and post-reperfusion periods.

CONCLUSIONS

The results of the present study suggest that differences in Hyp and Xan concentrations between renal and peripheral veins reflect metabolic alterations in renal tissue during reperfusion and may be useful for graft function monitoring during reperfusion.

Oxypurine and nucleoside concentrations in renal veins during reperfusion are predictors of early graft function

OBJECTIVE

To examine whether purine and pyrimidine nucleoside concentrations as well as oxypurine concentrations in renal and peripheral veins during reperfusion correlate with graft function parameters.

MATERIAL AND METHODS

The study population comprised 25 recipients of cadaver kidney transplant. A first blood sample was taken from the recipient's peripheral vein before anastomosing the kidney allograft vessels with the recipient's iliac vessels. Subsequent samples were taken from the allograft renal vein and the recipient's peripheral vein 5 min after beginning reperfusion. High-performance liquid chromatography was done to measure plasma concentrations of the oxypurines hypoxanthine (Hyp), xanthine (Xan) and uric acid and the nucleosides guanosine, inosine (Ino) and uridine (Urd).

RESULTS

Concentrations of Hyp, Xan and Ino were significantly higher in the renal than the peripheral vein. The differences between the Xan, Hyp, Ino and Urd plasma concentrations in the renal and peripheral veins before and 5 min after reperfusion correlated positively and significantly with serum creatinine concentrations 24 and 72 h after graft transplantation. Moreover, the concentrations of Hyp were significantly increased in renal transplant recipients with delayed graft function.

CONCLUSION

The results of this study suggest that the concentration of Hyp in the kidney allograft vein can be a useful predictor of early graft function.

Formation of Ascorbate Radicals as a Measure of Oxidative Stress: An In Vitro Electron Spin Resonance-Study Using 2,2–Azobis (2-Amidinopropane) Dihydrochloride as a Radical Generator

Reactive oxygen species (ROS) are continuously formed in biological systems. Any increase in radical production or decrease in the defense against ROS induces oxidative stress. This imbalance between ROS formation and ROS detoxification is believed to be involved in a variety of pathogenic processes, including ischemia-reperfusion injury. Various markers indicating oxidative stress has been used in experimental and clinical studies. One of them is ascorbate free radical (AFR), electron spin resonance intensity of which correlates with the severity of radical formation. We investigated the impact of alkyl peroxyl radicals produced by 2,2-Azobis (2-amidinopropane) dihydrochloride decomposition on the magnitude of the AFR signal. Our data confirmed the principal applicability of AFR as a nontoxic marker of radical generation.

Effect of trimetazidine on the nucleotide profile in rat kidney with ischemia-reperfusion injury

Ischemia-reperfusion injury is often responsible for delayed graft function after transplantation. Trimetazidine (TMZ) is an antioxidant agent used to protect grafts from ischemia-reperfusion injury. The aim of the study was to examine the effect of TMZ on nucleotide profile in rat kidney with ischemia-reperfusion injury. The study was carried out on Wistar rats divided into two groups: animals treated with TMZ and control group receiving placebo. TMZ 10mg/kg/day was administrated for 30 days. Concentrations of adenosine triphosphate (ATP), adenosine diphosphate (ADP), adenosine monophosphate (AMP), adenosine (Ado), guanosine triphosphate (GTP), guanosine diphosphate (GDP), guanosine monophosphate (GMP), guanosine (Guo), inosine monophosphate (IMP), inosine (Ino), hypoxanthine (Hyp), xanthine (Xan), uric acid (UA), uridine (Urd), nicotinamide adenine dinucleotide (NAD) and nicotinamide adenine dinucleotide phosphate (NADP) were determined in kidney tissues after ischemia-reperfusion using HPLC. The total adenine nucleotide concentration (TAN) and adenylate energy charge (AEC) were also determined. Moreover the kidneys were evaluated histologically. Tissue concentrations of ATP, ADP, AMP, TAN and AEC were significantly increased in kidneys from rats treated with TMZ in comparison with rats receiving placebo. Concentrations of products of nucleotide degradation: inosine (Ino), guanosine (Guo) and uridine (Urd), as well as oxypurines: Hyp and Xan, were significantly decreased in rats treated with trimetazidine. Moreover, significantly less pronounced acute tubular necrosis was observed in kidneys of rats treated with TMZ. These results suggest that trimetazidine protects against dephosphorylation of nucleotides and ischemic damage.

Preoperative feeding preserves heart function and decreases oxidative injury in rats

OBJECTIVE

The nutritional status of a patient has been implicated as an important factor in the development of postoperative complications. Fasting before an operation may have detrimental effects on the metabolic state. We hypothesized that there was a positive correlation between preoperative nutritional status and postoperative organ function.

METHODS

Preoperative feeding was compared with fasting with respect to effects on organ function and biochemical parameters in an animal model of extensive large abdominal surgery. Male Wistar rats were fed ad libitum or fasted for 16 h, after which the arteria mesenterica superior was clamped for 60 min followed by 180 min of reperfusion.

RESULTS

After the ischemic period, heart function was significantly better in animals that were fed ad libitum than in fasted animals. Moreover, after intestinal ischemia and reperfusion, fed rats showed significantly higher levels of intestinal adenosine triphosphate and a significantly higher malondialdehyde concentration in the intestine and lung than did fasted rats. The ratio of adenosine triphosphate to adenosine diphosphate in the liver, an indicator of energy status, in fed rats was similar to that in a sham group, whereas fasted animals showed a significantly lower value.

CONCLUSIONS

Preoperative nutrition in contrast to fasting may attenuate ischemia/reperfusion-induced injury and preserve organ function in the rat.

Expression of HSP 70 and its mRNAS during ischemia-reperfusion in the rat bladder

HSP 70 is an important protein that repairs damaged tissue after injury. In the present study, we investigated the expression of HSP 70 and its mRNAs during ischemia-reperfusion in the rat bladder. Rat abdominal aorta was clamped with a small clip to induce ischemia-reperfusion injury in the bladder dome. Male Wistar rats, 8 weeks old, were divided into six groups: controls, 30-min ischemia, 30-min ischemia and 30-, 60-minute, 1- and 7-day reperfusion, groups A, B, C, D, E, and F, respectively. In functional studies, contractile responses to carbachol were measured in these groups. The expression of HSP 70-1/2 mRNAs was quantified using a real-time PCR method, and that of HSP 70 proteins was measured using ELISA in the bladders. In the functional study, Emax values of carbachol to bladders in the A, B, C, D, E and F groups were 9.3 +/- 1.3, 7.9 +/- 1.7, 4.3 +/- 0.8, 4.2 +/- 0.7, 4.5 +/- 0.6, and 8.1 +/- 1.2 g/mm2, respectively. In the control group, the expression of HSP 70-1/2 mRNA was detected, and the expression of HSP 70-1 mRNAs was significantly higher than that of HSP 70-2 mRNAs in each group. The expression of HSP 70-1 mRNA increased in groups B and C, but decreased in groups D, E, and F. The expression of HSP 70-2 mRNA in group C was significantly higher than that of groups A, D, E, and F. The expression of HSP 70-1/2 mRNAs after 1 day or 1 week of reperfusion was similar to control levels. The expression of HSP 70 proteins was increased shortly after the expression of their mRNAs. The expression of HSP 70 after 1 day or 1 week of reperfusion was almost identical to control levels. Our data indicate that contractile responses of the bladder were decreased by ischemia reperfusion, and that expression of HSP 70 and its mRNAs appeared to increase after a short period of the insult.

Evaluation of heat shock protein 70 expression in renal parenchyma subjected to shockwave lithotripsy

PURPOSE

In this experimental study in a rabbit model, renal parenchymal heat shock protein 70 (hsp70) levels were assessed in an attempt to evaluate the traumatic effects of high-energy shockwaves (HESW), which have been found to induce transient ischemia during the procedure.

MATERIALS AND METHODS

Eighteen white New Zealand rabbits, each weighing 3 to 5 kg, were included in the study. The animals were divided into three groups, and various numbers of shockwaves (1000, 1500, or 2000) were applied to the same kidney of all animals under fluoroscopic localization with a Stonelith V5 lithotripter. Untreated contralateral kidneys were evaluated as controls. Following HESW application, the treated and untreated kidneys were removed surgically after 24 hours or 7 days. Tissue hsp70 levels were assessed by an immunohistochemistry method.

RESULTS

During early follow-up (24 hours), both treated and untreated kidneys demonstrated moderate to severe hsp70 positivity. The number of positive tubules increased as the number of shockwaves increased, and positivity became more evident, possibly because of a higher degree of tissue damage. Contralateral kidneys demonstrated a limited degree of hsp70 positivity, although it was not as evident as in the treated kidneys. Assessment of tissue hsp70 levels during late follow-up (7 days) demonstrated moderate or limited degrees of positivity in the treated kidneys. Limited or no positivity could be demonstrated in the untreated kidneys during this period.

CONCLUSIONS

Taking the known traumatic effects of HESW and the results of this study into account, the increasing positivity of hsp70 in parallel with the increasing number of shockwaves led us to think about a possible limited degree of ischemia induced by this procedure, as the traumatic effects of HESW were pronounced, as judged by tissue hsp70 positivity.

Nucleotides modulate renal ischaemia-reperfusion injury by different effects on nitric oxide and superoxide

1. The present study investigated the effects of kidney ischaemia duration on nitric oxide (NO) and superoxide (O2-) generation at reperfusion and the role of xanthine and adenosine as mediators of NO/O2- generation. 2. The effect of the duration of ischaemia on renal nucleotide levels was studied in two ischaemic groups (10 and 30 min). The role of adenosine and xanthine was studied in ischaemic-reperfused groups (subjected to 10 and 30 min ischaemia and 60 min reperfusion). 3. Tissue levels of adenosine decreased significantly after 30 min ischaemia, whereas xanthine/hypoxanthine levels increased concomitantly with renal dysfunction and histological damage. 4. Nitric oxide production increased significantly after 10 min ischaemia and 60 min reperfusion, whereas lipoperoxidation increased significantly after 30 min ischaemia and 60 min reperfusion. The administration of theophylline (40 mg/kg, i.p.) reversed the early increase in NO production. 5. Xanthine supplementation decreased renal function and increased lipoperoxidation. 6. In conclusion, NO/O2- production and the subsequent renal injury/dysfunction may be modified by changes in the adenosine and xanthine levels of the injured kidney, although the present data show a significant in vivo role only for xanthine.

Hydrogen peroxide production by monoamine oxidase during ischemia/reperfusion

Reactive oxygen species have been postulated to play a crucial role in the pathogenesis of renal ischemia-reperfusion injury. However, the intracellular sources of reactive oxygen species during ischemia-reperfusion are still unclear. In the present study, we examined whether catecholamine-degrading enzymes monoamine oxidases contribute to hydrogen peroxide (H(2)O(2)) generation during ischemia-reperfusion using an in vivo rat model of unilateral renal ischemia. The monoamine oxidases were characterized in homogenates of renal cortex by enzyme assay and by Western blot analysis. The monoamine oxidase-dependent H(2)O(2) production was measured by luminol-amplified chemiluminescence assay. Renal monoamine oxidase activity and H(2)O(2) generation by monoamine oxidases were suppressed during ischemia. The monoamine oxidase-dependent H(2)O(2) production was observed during the first 15 min of reperfusion. In addition, enzyme assays showed that monoamine oxidase is also activated in this period. Rat pre-treatment with the irreversible inhibitor of monoamine oxidase, pargyline, prevented H(2)O(2) production. These data suggest that monoamine oxidases are a potential source of H(2)O(2) generation in the early reperfusion following ischemia, which could be involved in renal ischemia-reperfusion injury.

Heat stress protection against mesenteric I/R-induced alterations in intestinal mucosa in rats

Prior induction of heat shock protein 70 (HSP70) protects against ischemia-reperfusion (I/R) mucosal injury, but the ability of HSP70 to affect I/R-induced alterations in epithelial cell function is unknown. Rats subjected to whole body hyperthermia (41.5-42 degrees C for 6 min) increased HSP70 and heat shock factor 1 mRNA expression, reaching a maximum 2 h after heat stress and declining thereafter. HSP70 production was maximally elevated at 4 h after heat stress and remained elevated until after 12 h. Heat stress alone had no effect on mucosal function except to enhance secretion in response to ACh. Heat stress provided complete morphological protection against I/R-induced mucosal injury but did not confer a similar protection against I/R-induced decreases in mucosal resistance, sodium-linked glucose absorption, or tachykinin-mediated chloride secretion. Heat stress, however, attenuated the I/R-induced suppression of ACh response, and this effect was dependent on enteric nerves. Thus induction of heat shock protein 70 is associated with the preservation of mucosal architecture and attenuation of some specific functional alterations induced by I/R.