Regulatory effects of interleukin-10 on lung ischemia-reperfusion injury

OBJECTIVE: Interleukin-10, a cytokine with antiinflammatory activities, was studied to determine its effects on development of early lung reperfusion injury. METHODS: Adult male rats underwent 90 minutes of left lung ischemia followed by 4 hours of reperfusion. Time-matched sham-operated control rats underwent hilar dissection but not lung ischemia. Lung injury was measured by vascular permeability to bovine serum albumin tagged with iodine 125. To evaluate the effect of exogenous interleukin-10, additional animals received interleukin-10 intravenously before ischemia. To assess the role of endogenous interleukin-10, animals received rabbit antimouse interleukin-10 immunoglobin G (or preimmune rabbit immunoglobin G) before ischemia. RESULTS: Compared with sham control rats, ischemia-reperfusion control rats demonstrated significantly more lung injury. Animals receiving interleukin-10 had significantly less lung injury than did ischemia-reperfusion control rats. Animals receiving antiinterleukin-10 had significantly more lung injury than did animals receiving preimmune immunoglobin G. Alveolar macrophages from animals after 90 minutes of lung ischemia produced more tumor necrosis factor-alpha in culture than did unstimulated macrophages; this production was reduced significantly by the addition of interleukin-10 to the culture medium. CONCLUSION: Endogenous interleukin-10 has a protective effect against early lung reperfusion injury, and interleukin-10 administration can reduce lung reperfusion injury, perhaps in part through its ability to reduce production by alveolar macrophages of tumor necrosis factor-alpha, a known proinflammatory cytokine.     

Mediators of injury and inflammation

Mediators play a key role in the development of systemic inflammatory response syndrome (SIRS), multiple organ dysfunction syndrome, and multiple organ failure of vital organs. In this short review, we update our knowledge on these mediator networks. First, we summarize the stimuli that occur during severe trauma (intraoperative stress), including polymorphonuclear neutrophil-derived tissue-damaging substances, complement activation products, and adherence molecules such as selectins. The gut in shock is discussed as an important intermediate step in the transition from noninfectious to infectious SIRS. Second, we describe the mediators, including cytokines, nitric oxide, phospholipase A2, platelet-activating factor, and procoagulatory substances, that are released during sepsis. The release of mediators depends primarily on the severity of the trauma, shock, or sepsis and secondarily on the activation of the various cascades of mediators during posttraumatic/postoperative complications. The mediators are thus of decisive importance regarding the intensity of organ damage and the outcome.     

The role of endogenous nitric oxide in modulating ischemia-reperfusion injury in the isolated, blood-perfused rat lung

Ischemia-reperfusion (IR) lung injury occurs after various clinical procedures, including cardiopulmonary bypass. It is not clear whether endogenous nitric oxide (NO) is protective or injurious in lungs subjected to IR. Thus, in this study we examined the contribution of endogenous NO to IR injury in isolated, blood-perfused rat lungs. Lungs of male Wistar rats (300 g) were subjected to 30 min ischemia and 180 min reperfusion (I30R180). Lungs were sampled for inducible nitric oxide synthase (i-NOS) mRNA expression (each n = 3) and NOS enzyme activity (each n = 4) at different time points. NOS inhibitors NG-nitro-L-arginine-methyl ester (10[-4] M) and aminoguanidine (10[-4] M) were used to study the contribution of NO to IR injury in lungs subjected to I30R30 and I30R180. The contribution of i-NOS to IR lung injury was studied by inducing i-NOS enzyme with Salmonella lipopolysaccharide, followed by I30R30. We found that ischemia-reperfusion alone can upregulate i-NOS mRNA and i-NOS enzyme activity (p < 0.05, ANOVA), but downregulate constitutive NOS enzyme activity over 180 min reperfusion. Endogenously produced NO is protective against lung injury in I30R180 in normal rats and lung injury in I30R30 in septic rats. NO is also pivotal in maintaining pulmonary vascular homeostasis in septic rat lungs undergoing IR.     

Donor treatment with the lazeroid U74389G reduces ischemia-reperfusion injury in a rat lung transplant model

BACKGROUND: Antioxidant treatment with lazeroids has proven beneficial for the amelioration of reperfusion injury in experimental lung transplantation. This study compares the effect of donor versus recipient treatment on immediate postoperative graft function. METHODS: A model of acute double-lung transplantation in rats was used to assess graft function. Transplanted controls after 2 (group I) and 16 hours of ischemia (group II) were compared to a recipient (group III; 16-hour ischemia) and a donor treatment group (group IV; 16-hour ischemia) using the lazeroid U74389G (6 mg/kg). Serial assessment of alveolar-arterial oxygen difference, dynamic lung compliance, airway and pulmonary vascular resistance was obtained during a 2-hour reperfusion period. Final analysis included survival, weight gain, and histologic examination. RESULTS: Graft function was significantly better after 2 hours of ischemia than in any of the three 16-hour ischemia groups (II, III, IV). After 16 hours of ischemia, donor treatment provided superior graft function with respect to dynamic lung compliance, airway resistance, and alveolar-arterial oxygen difference when compared with groups II and III. The pulmonary vascular resistance was significantly higher in group III when compared with groups II and IV. Graft weight increase reflecting edema was highest in groups III (104%) and II (98%). CONCLUSIONS: After prolonged ischemia only donor treatment with the lazeroid U74389G was able to significantly reduce ischemia-reperfusion-related graft dysfunction.     

The protective effect of L-arginine on ischemia-reperfusion injury in rat skin flaps

The objective of this study was to examine whether the administration of L-arginine, a precursor of nitric oxide and substrate of nitric oxide synthase, prior to reperfusion could lead to decrease in neutrophil-mediated tissue injury and improved flap survival. Epigastric island skin flaps were elevated in 70 rats and rendered ischemic. Thirty minutes prior to reperfusion, the rats were treated with intraperitoneal saline (n = 15), L-arginine (n = 15), D-arginine (n = 15), or N omega-nitro-L-arginine methylester plus L-arginine in equimolar amounts (n = 15). Flap survival at 7 days and neutrophil counts at 24 hours were evaluated. Flap necrosis as expected in the sham group of animals (n = 10) was 0.0 percent, while the control (saline-treated) animals had 59.6 percent necrosis. Animals treated with L-arginine demonstrated a significant decrease in flap necrosis to 12.7 percent. This protective effect was almost completely negated by N omega-nitrol-L-arginine methylester, which significantly increased flap necrosis to 49.3 percent and was much less pronounced with D-arginine (28.6 percent). Neutrophil counts were significantly decreased in flaps from L-arginine-treated and sham animals versus both saline and N omega-nitro-L-arginine methylester-treated groups. We conclude that administration of L-arginine prior to reperfusion can significantly reduce the extent of flap necrosis and flap neutrophil counts due to ischemia-reperfusion injury. This protective effect is completely negated by nitric oxide synthase inhibition. Since L-arginine reduces the number of neutrophils within the flap and the extent of flap necrosis only in the presence of active nitric oxide synthase, we hypothesize that this protective effect of L-arginine on ischemia-reperfusion injury is secondary to a nitric oxide-mediated suppression of neutrophil-mediated injury.     

A CD18 antibody prevents lung injury but not hypotension after intestinal ischemia-reperfusion

Antibodies to the neutrophil CD18 integrin have been shown to ameliorate the local effects of intestinal ischemia and reperfusion (I/R). In addition to local mucosal injury, intestinal I/R results in systemic hypotension and injury to the lungs with lung leukosequestration. This study tests the effect of a CD18 monoclonal antibody on the hypotension and lung injury after intestinal I/R. In anesthetized rabbits, the superior mesenteric artery was clamped for 60 min followed by 3 h of reperfusion. Animals were treated with saline, an anti-CD18 monoclonal antibody (R15.7 MAb), or nonspecific immunoglobulin G. Another non-ischemic group were sham controls. Neutrophil sequestration was assessed by measure of lung myeloperoxidase (MPO) and permeability by lung-to-blood concentration ratio of 125I-labeled bovine serum albumin and wet-to-dry weight ratio. Immediately after reperfusion, mean arterial pressure fell to 49 +/- 2.1 mmHg and remained at this level. The hypotension was unaffected by treatment with R15.7 MAb. Thirty minutes after reperfusion, the circulating white blood cell count fell to 2.91 +/- 0.53 x 10(3)/mm3 vs. sham 6.40 +/- 0.66 x 10(3)/mm3 (P < 0.05). Treatment with R15.7 MAb prevented this fall in white blood cell count (5.75 +/- 1.59 x 10(3)/mm3). At 3 h of reperfusion in saline-treated animals there was increased MPO, 74.8 +/- 4.9 U/g vs. 42.0 +/- 4.8 U/g in sham animals (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)     

Participation of nitric oxide in the mucosal injury of rat intestine induced by ischemia-reperfusion

The dual role of nitric oxide as a cytoprotective or a cytotoxic free radical gas has been noted in various types of pathophysiological conditions, including the digestive system. The aim of this study was to examine the role of nitric oxide in the mucosal injury induced by ischemia-reperfusion in the rat small intestine. A transient intestinal ischemia was produced in the catheterized ileal segments of rats by occluding the anterior mesenteric artery for 60 min. Nitric oxide metabolites (NO2- and NO3-) and lactate dehydrogenase activity in perfusates of the intestinal lumen were measured over 5 hr periods. The time-course of histological changes in small intestine was also observed. After ischemia-reperfusion, nitric oxide release in the intestinal lumen increased significantly and the dynamics of nitric oxide release correlated with that of lactate dehydrogenase leakage. The administration of NG-nitro-L-arginine methyl ester (1.0-2.5 mg/kg) inhibited this increased nitric oxide release and the lactate dehydrogenase leakage and afforded protection against the mucosal injury induced by ischemia-reperfusion. In conclusion, the nitric oxide production that was accelerated by ischemia-reperfusion of small intestine may possibly participate in the breakdown of intestinal mucosa after ischemia-reperfusion insult.     

Vitamin C reduces ischemia-reperfusion injury in a rat epigastric island skin flap model

We have examined the effects of lumbar extradural administration of 1% etidocaine 10 ml on somatosensory evoked potentials to posterior tibial nerve stimulation measured in the cervical extradural space. Eight patients, anaesthetized with propofol and nitrous oxide, were studied before hysterectomy and a control group received a similar anaesthetic and 0.9% sodium chloride solution 10 ml in the lumbar extradural space. Etidocaine decreased significantly overall amplitude of the evoked potentials and the amplitudes of all peaks, between 30 and 50 min after extradural injection. The effects of etidocaine on spinal cord conduction were greater than those found previously for lignocaine and bupivacaine, suggesting that it is the local analgesic of choice for inhibiting afferent conduction.     

Prostacyclin analog-suppressed ischemia-reperfusion injury of the rat liver: evaluation by calpain mu activation

Advances in perinatal and neonatal health care over the past few decades have resulted in a substantial reduction in perinatal mortality. Some of this improvement has been attributed to antepartum fetal surveillance techniques. The primary objective of antepartum fetal surveillance techniques is to avoid fetal deaths. An ideal secondary objective is to avoid neonatal complications related to intrauterine asphyxia. In this article, some of the difficulties in evaluating existing antepartum fetal surveillance techniques are highlighted. Some of the epidemiological methods for evaluating a screening test are reviewed and their importance discussed with reference to fetal testing procedures. Lastly, the possibility of considering indication-specific fetal testing to improve perinatal morbidity is examined.     

Protective effect of salvianolic acid a on ischemia-reperfusion induced injury in isolated rat heart

BACKGROUND: Recognition of advanced abdominal pregnancy and care of the patient afflicted with it may present formidable challenges. Aside from the difficulty of diagnosing the problem and thereby delaying necessary intervention, management can be difficult at best, even when the condition is relatively uncomplicated. When it is compounded by a life-threatening complication, such as uncontrollable hemorrhage, it challenges the skills of the most experienced obstetrician and the resources of the best-equipped facility and its personnel. CASE: Partial placental separation was encountered at surgery; it progressed intraoperatively despite the care taken to avoid disturbing the placental implantation site. Severe hemorrhage was controlled by a combination of aortic compression, packing and use of large "liver" sutures incorporating the uterine wall for tamponade of the principal placental implantation site, on the mesentery. CONCLUSION: It is important to be prepared to deal with the complication of intense intraabdominal bleeding in the course of intraoperative management of abdominal pregnancy.     

Pattern of injury and the role of neutrophils in reperfusion injury of rat lung

Using a rat lung model, we sought to characterize the time course for ischemia-reperfusion injury and the role of neutrophils in the development of injury. Adult male Long-Evans rats underwent left thoracotomy with dissection and clamping of the left pulmonary artery, bronchus, and vein for 90 min, resulting in complete left lung ischemia. The lungs were then ventilated and reperfused for up to 4 hr. Time-matched sham animals underwent the identical thoracotomy and hilar dissection, but the lungs were not rendered ischemic. Using vascular permeability of 125I-labeled bovine serum albumin as a measure of reperfusion injury, a bimodal pattern of injury was observed. Compared to sham controls, animals undergoing ischemia-reperfusion demonstrated a significant early phase of lung injury at 30 min of reperfusion (P < 0.0001), followed by partial recovery. A second peak of lung injury was noted after 4 hr of reperfusion (P < 0.001). Myeloperoxidase activity in reperfused lung tissue, a measure of neutrophil sequestration, increased during the reperfusion time course. To determine the role of neutrophils in the development of lung reperfusion injury, additional animals undergoing the identical ischemia-reperfusion protocol received either rabbit anti-rat neutrophil serum or preimmune serum the day prior to operation. Profound neutropenia (< 75/mm3 blood) was confirmed by differential leukocyte counts. Neutropenia had no protective effect against microvascular permeability at 30 min of reperfusion, but there was a significant reduction in lung injury at 4 hr (P < 0.005). We conclude that, during lung ischemia-reperfusion, there is a bimodal pattern of injury, consisting of both neutrophil-independent and neutrophil-mediated events.     

N-acetyl cysteine attenuates acute lung injury in the rat

Bacterial infections, especially cholangitis, are still common complications after liver transplantation (LTx). During recent years, multiresistant enterococci have become a nosocomial problem in transplant units. The present prospective study on 26 patients, including 24 patients with chronic liver disease, demonstrated that enterococci were the predominant micro-organism involved in post-LTx bacterial infections. They were cultured in the feces and in other sites of 10 out of 13 (77%) patients who underwent extensive examinations. Ampicillin-resistant Enterococcus faecium strains were isolated in urine or feces of 2 of the 13 patients prior to LTx. Similarly, resistance to ampicillin and gentamicin, the empirically used antibiotics for patients with fever of unknown origin, was found in E. faecium strains in 3 and 2 patients, respectively. Moreover, multiresistant E. faecium and E. faecalis strains were demonstrated in 46% of the patients in the postoperative period (3 months). However, no vancomycin-resistant enterococci were isolated. The use of antibiotics within 4 months prior to LTx significantly increased the risk of developing ampicillin-resistant bacteria at the time of LTx and of infections with bacteria of enteric origin after LTx (P = 0.03 and 0.01, respectively). We conclude that stool and urine cultures performed prior to LTX may be useful for selecting prophylactic antibiotic regimens.     

Surfactant administration reduces testicular ischemia-reperfusion injury

PURPOSE: The mechanism of testicular ischemia-reperfusion injury has not been well delineated. We determined the efficacy of a biocompatible surfactant (tetronic 1107) to reduce tissue injury and evaluated cell membrane integrity as reflected by calcium ion permeability in an in vivo animal model of testicular ischemia-reperfusion. MATERIALS AND METHODS: Three groups of male Sprague-Dawley rats (6 per group) were studied. Group 1 was the nonoperative control, and groups 2 and 3 underwent 4 hours of unilateral testicular ischemia followed by 4 hours of reperfusion. Ten minutes after reperfusion 0.4 ml. saline was administered intravenously to group 2 and 180 mg./kg. surfactant tetronic 1107 to group 3. 99mTechnetium pyrophosphate was used to monitor calcium ion uptake by the ipsilateral and contralateral testicles. Both testicles were also examined histologically. RESULTS: The surfactant treated animals had markedly diminished hemorrhagic discoloration and vascular congestion compared to saline treated animals. These results were confirmed microscopically with improved nuclear chromicity and disarray of germ cell layers of the seminiferous tubules. The surfactant treated group also had a statistically significant (p <0.05) reduction in radiotracer uptake compared to the saline treated animals, confirming a reduction in calcium ion permeability. CONCLUSIONS: The results of this study suggest that tetronic 1107 is effective in reducing tissue damage in a testicular ischemia-reperfusion animal model.     

The role of xanthine dehydrogenase (xanthine oxidase) in ischemia-reperfusion injury in rat kidney

Xanthine dehydrogenase (XDH) and xanthine oxidase (XO) are enzymes involved in the metabolism of purines in various organisms. XO produces superoxide radicals, suggesting that is responsible for tissue ischemia-reperfusion injury. To test this notion further studies were performed on rat kidneys and the time course of changes in purine nucleotides, oxypurines and XDH and XO activity was determined. At 24 hours after reperfusion subsequent to 30-minute ischemia, serum creatinine increased to 0.83 +/- 0.74 mg/dl from 0.28 +/- 0.06 mg/dl (the level prior to ischemia, the control). Renal ATP and ADP contents were reduced after ischemia lasting for 30 minutes and restored 10 minutes after reperfusion following 30 minutes of ischemia. The renal AMP content increased after 30 minutes of ischemia and recovered within 10 minutes after reperfusion. The total adenine nucleotide (TAN) content was reduced gradually during ischemia-reperfusion in the rat kidney. Although the energy charge was reduced following 30 minutes of ischemia, it was restored to the control level 10 minutes following reperfusion. Hypoxanthine (HX) and xanthine (X), which had accumulated at 30 minutes after ischemia, were reduced to the control levels 10 minutes after reperfusion. There were no significant changes in the pre-ischemia values of total XDH and XO activities or XDH/XO ratio during the period nor at various time intervals (up to 24 hours) during reperfusion. It was shown that HX and X accumulate without significant conversion of XDH to XO during ischemia. Therefore the putative role of XO in ischemia-reperfusion injury seems to more complex than initially predicted.     

The effects of thyroid hormone modulation on rat liver injury associated with ischemia-reperfusion and cold storage

We investigated the effects of thyroid hormone modulation on liver injury associated with ischemia-reperfusion (I-R) and cold storage in rats. First, euthyroid and thyroxine (T4)-pretreated rats were exposed in vivo to 20-min global liver ischemia, then 30-min reperfusion. Liver injury was assessed by measuring serum alanine aminotransferase (ALT) levels. Liver concentrations of adenine nucleotides, reduced glutathione (GSH), and oxidized glutathione were evaluated. Second, rats were given the antithyroid drug propylthiouracil (PTU). Livers stored at 0-1 degrees C in Euro-Collins' solution for 20 h were reperfused at 37 degrees C for 15 min. Lactate dehydrogenase (LDH) in the effluent perfusate and bile flow were evaluated during reperfusion. Serum ALT levels increased after ischemia and I-R. ALT increased significantly more in T4-pretreated than in euthyroid rats after ischemia and I-R. Preischemic levels of adenosine triphosphate (ATP) were significantly lower in livers from T4-pretreated than in euthyroid rats (6.22 +/- 0.7 and 11 +/- 0.9 nmol/mg protein, respectively; P < 0.05). After ischemia, liver ATP was similarly reduced in T4-pretreated and euthyroid rats. After reperfusion, ATP partially recovered in euthyroid rats but remained low in T4-pretreated rats (6.7 +/- 1.0 and 1.91 +/- 0.7 nmol/mg protein, respectively; P < 0.05). Preischemic levels of liver GSH decreased to 44% in T4-pretreated rats. After ischemia, GSH decreased similarly in euthyroid and T4-pretreated rats. GSH recovered promptly after reperfusion in euthyroid rats but remained low in T4-pretreated rats (13.9 +/- 3.3 and 3.9 +/- 0.9 nmol/mg protein, respectively; P < 0.02). During reperfusion after cold storage, LDH in effluent perfusate was significantly lower and bile flow higher in livers from PTU-pretreated rats than from euthyroid rats. The histopathological changes observed after I-R and cold storage confirmed the biochemical findings. Our results suggest that T4 administration exacerbates pretransplant liver damage by increasing liver susceptibility to I-R, whereas PTU administration reduces the liver injury associated with cold storage. Implications: We studied the effects of thyroid hormone modulation on liver injury associated with ischemia-reperfusion and cold storage in rats. Thyroxine administration increased susceptibility to ischemia-reperfusion injury, whereas the antithyroid agent propylthiouracil reduced the deleterious effects associated with cold storage.