Pyrrolidine Dithiocarbamate Reduces Lung Injury Caused by Mesenteric Ischemia/Reperfusion in a Rat Model

Background Pyrrolidine dithiocarbamate (PDTC) is a low-molecular thiol antioxidant and potent inhibitor of nuclear factor-κB (NF-κB) activation. It has been shown to attenuate local harmful effects of ischemia/reperfusion (I/R) injury in many organs. In this study, we aimed to study the effect of PDTC on lung reperfusion injury induced by superior mesenteric occlusion. Methods Male Wistar-albino rats randomized into three groups: (1) sham-operated control group (n = 12), laparotomy without I/R injury; (2) intestinal ischemia/reperfusion (I/R) group (n = 12), 60 min of ischemia by superior mesenteric occlusion followed by 2 h of reperfusion; and (3) I/R+PDTC-treated group (n = 12), 100 mg/kg injection of PDTC intravenously, 30 min after the commencement of reperfusion. Evans blue dye was injected to half of rats in all groups before the induction of I/R. We assessed the degree of pulmonary tissue injury biochemically by measuring malondialdehyde (MDA), glutathione (GSH), and nitric oxide (NO) levels, and histopathologically by establishing pulmonary neutrophil sequestration and acute lung injury scoring. Pulmonary edema was evaluated by Evans blue dye extravasation, as well as lung tissue wet/dry weight ratios. Results Pyrrolidine dithiocarbamate treatment significantly reduced the MDA and NO levels, and increased the GSH levels in the lung parenchyma, biochemically (p < 0.05), and atteneuated the pulmonary parenchymal damage, histopathologically (p < 0.05). However, pulmonary neutrophil sequestration was not affected by postischemic treatment with PDTC (p > 0.05). Pyrrolidine dithiocarbamate administration also significantly alleviated the formation of pulmonary edema, as evidenced by the decreased Evans blue dye extravasation and organ wet/dry weight ratios (p < 0.05). Conclusions This study showed that postischemic treatment with PDTC significantly attenuated the lung reperfusion injury. Further clinical studies are needed for better understanding of the specific mechanisms of PDTC protection against I/R-related organ injury and to clarify whether PDTC may be a useful therapeutic agent during particular operations where remote organ I/R injury occurs.     

Activated protein C attenuates intestinal reperfusion-induced acute lung injury: an experimental study in a rat model

BACKGROUND: Activated protein C (APC) is a serine protease with anticoagulant and anti-inflammatory activities. APC has been shown to attenuate local deleterious effects of ischemia/reperfusion (I/R) injury in many organs. We aimed to investigate the effects of APC on lung reperfusion injury induced by superior mesenteric occlusion. METHODS: Male Wistar-Albino rats were allocated into 4 groups: (1) sham-operated group, laparotomy without I/R injury (n = 12); (2) sham + APC group, identical to group 1 except for APC treatment (n = 12); (3) intestinal I/R group, 60 minutes of ischemia followed by 3 hours of reperfusion (n = 12); and (4) I/R + APC-treated group, 100 microg/kg injection of APC intravenously, 15 minutes before reperfusion (n = 12). Evans blue dye was injected into half of the rats in all groups. We assessed the degree of pulmonary tissue injury by measuring activities of oxidative and antioxidative enzymes, as well as nitrate (NO(3)(-))/nitrite (NO(2)(-)) levels, biochemically. We evaluated acute lung injury (ALI) by establishing pulmonary neutrophil sequestration and ALI scoring histopathologically. Pulmonary edema was estimated by using Evans blue dye extravasation and wet/dry ratios. The plasma levels of proinflammatory cytokines and D-dimer were measured. RESULTS: APC treatment significantly reduced activities of oxidative enzymes and nitrate/nitrite levels in the lung tissues, and plasma levels of proinflammatory cytokines and D-dimer, and also significantly increased activities of antioxidative enzymes (P < .05). Pulmonary neutrophil sequestration and ALI scores were decreased significantly with APC administration (P < .05). In addition, APC treatment significantly alleviated pulmonary edema (P < .05). CONCLUSIONS: This study clearly showed that APC treatment significantly attenuated the lung reperfusion injury. Further clinical studies are required to clarify whether APC has a useful role in the reperfusion injury during particular surgeries in which I/R-induced organ injury occurs.     

Role of tumour necrosis factor in lung injury caused by intestinal ischaemia-reperfusion

BACKGROUND: Despite the well known inflammatory effects of tumour necrosis factor alpha (TNF), the mechanism of TNF-mediated lung injury following ischaemia-reperfusion (I/R) is still unclear. In this study, the role of TNF in the development of acute lung injury following intestinal I/R was investigated. METHODS: Male Wistar rats underwent either sham operation (n = 10), 1 h of superior mesenteric artery occlusion and 2 h of reperfusion (I/R, n = 10), or pretreatment with anti-TNF polyclonal antibody 2 mg/kg and I/R (n = 6). Lung injury was evaluated by Evans blue dye concentration, immunohistochemical staining and morphometric analysis. Intestinal injury was assessed by Evans blue dye concentration and histological examination. RESULTS: Intestinal I/R resulted in lung injury characterized by an increase in Evans blue dye concentration, neutrophil sequestration, and obvious staining for expression of pulmonary CD11b and CD18. Pretreatment of animals with anti-TNF antibody led to a reduction in the sequestration of neutrophils, and a decrease in expression of pulmonary intracellular adhesion molecule 1 and CD18. Anti-TNF antibody pretreatment also reduced the intestinal microvascular injury but not histological grade after intestinal I/R. CONCLUSION: Treatment with an anti-TNF antibody resulted in a significant attenuation of lung injury following intestinal I/R. The data indicate that TNF is an important trigger for upregulation of pulmonary endothelial and neutrophil adhesion molecules after intestinal I/R.     

L-N6-(1-亚氨乙基)赖氨酸对大鼠移植肺缺血再灌注损伤的影响

目的 探讨L-N6-(1-亚氨乙基)赖氨酸(L-NIL)对大鼠移植肺缺血再灌注损伤的影响.方法 清洁级雄性SD大鼠18只,体重250～350 g,随机分为3组(n=6),假手术组(S组);肺移植组(L组)肺移植后恢复再灌注,冷缺血时间约1 h;L-NIL组再灌注即刻经尾静脉输注L-NIL 3 mg/kg.各组均于再灌注即刻经尾静脉注射0.5%伊文氏蓝0.2 ml.再灌注2 h时取左肺组织,测定肺湿/干重(W/D)比、伊文氏蓝含量、MDA含量、髓过氧化物酶(MPO)、诱导型一氧化氮合酶(iNOS)及内皮源性一氧化氮合酶(eNOS)活性;并行病理学观察.结果 与S组比较,L组肺组织W/D比和伊文氏蓝含量增加,MDA含量、MPO及iNOS活性升高,eNOS活性降低(P＜0.05).与L组比较,L-NIL组肺组织W/D比和伊文氏蓝含量减少,MDA含量、MPO及iNOS活性降低,eNOS活性升高(P＜0.05),肺组织毛细血管内充血减少,炎性细胞浸润减少.结论 再灌注早期静脉注射L-NIL可减轻大鼠移植肺缺血再灌注损伤.     

Topical hepatic hypothermia attenuates pulmonary injury after hepatic ischemia and reperfusion

Background: Prolonged periods of hepatic ischemia are associated with hepatocellular injury and distant organ dysfunction in experimental models. Neutrophils (PMN) and tumor necrosis factor (TNF)- have been implicated, mostly because of their local deleterious effects on the hepatocyte after hepatic ischemia and reperfusion (I/R) injury. We hypothesize that topical hepatic hypothermia (THH) reduces ischemia and reperfusion-induced hepatic necrosis, PMN infiltration, TNF- release, and consequent acute pulmonary injury.

Study Design: Sprague-Dawley rats (250 to 300 g) were evenly divided into three groups: 90 minutes of normothermic (37°C) partial hepatic ischemia (normothermic I/R), 90 minutes of hypothermic (25°C) partial hepatic ischemia (hypothermic I/R), and sham laparotomy (without ischemia). There were six animals in each experimental group per time point unless otherwise specified. Hepatic necrosis and PMN infiltration were evaluated and scored on hematoxylin and eosin-stained liver specimens 12 hours after reperfusion. Serum TNF- levels were determined by ELISA at 0 minutes, 15 minutes, 30 minutes, 1 hour, and 12 hours postreperfusion. Pulmonary PMN infiltration and vascular permeability were measured by myeloperoxidase activity and Evans blue dye extravasation, respectively, to quantitate pulmonary injury 12 hours after reperfusion.

Results: Normothermic I/R results in a significant increase in TNF- at 15 and 30 minutes (p < 0.005), PMN infiltration (p < 0.001), and hepatic necrosis (p < 0.001), compared with sham. Institution of THH reduced peak serum TNF- levels by 54% at 15 minutes (p < 0.005) and by 73% at 30 minutes (p < 0.001) postreperfusion compared with normothermic I/R. Similarly, hepatic PMN infiltration and necrosis at 12 hours were reduced by 60% (p < 0.05) and 47% (p < 0.05), respectively. Myeloperoxidase activity and Evans blue extravasation (measures of acute lung injury) were reduced by 42% and 39%, respectively, with institution of THH compared with animals undergoing normothermic I/R (p < 0.001).

Conclusions: These results demonstrate that THH protects the liver from ischemia and reperfusion-induced necrosis and PMN infiltration. In addition, THH reduces the serum levels of TNF- and associated pulmonary injury. These data suggest that the ischemic liver is a potential source of inflammatory mediators associated with hepatic ischemia and reperfusion-induced pulmonary injury.     

Pulmonary expression of inducible heme-oxygenase after ischemia/reperfusion of the lower extremities in rats

BACKGROUND: Expression of inducible heme-oxygenase (HO-1) has been shown to be increased in various inflammatory disorders, which may confer a protective role. The aim of our study was to assess pulmonary expression of HO-1 after ischemia/reperfusion (I/R) of the lower limbs in rats. MATERIALS AND METHODS: We compared three groups of rats (n = 5/group): one Sham group, and two I/R groups (aorta cross-clamped for 2 h followed by 2 h of reperfusion), one of which pre-treated with Zn-protoporphyrin (Zn-PP), a competitive inhibitor of HO (50 micromol/kg, i.p.). At the end of experiment, lungs were harvested for determination of HO activity and HO-1 expression by Western blot and immunohistochemistry. Lung injury was assessed by bronchoalveolar lavage, histological study, and determination of the lung Evans Blue dye content, an index of microvascular permeability. RESULTS: I/R of the lower limbs was responsible for acute lung injury (ALI), characterized by neutrophilic infiltration (87 +/- 20 x 10(3) neutrophils/mm(3), Sham group versus 191 +/- 38 x 10(3) neutrophils/mm(3), I/R group; P < 0.002) and an increase in lung Evans blue dye content: (74 +/- 6 microg/g, Sham group versus 122 +/- 48 microg/g, I/R group; P < 0.05). Pre-treatment with Zn-PP further increases the Evans Blue content (122 +/- 48 microg/g, I/R group versus 179 +/- 23 microg/g Zn-PP group P < 0.05) and the neutrophilic infiltration. Pulmonary heme-oxygenase activity, and HO-1 content were increased after I/R. (10.5 +/- 12 pmol bilirubin/mg protein/h, Sham group versus 101.2 +/- 66 pmol bilirubin/mg protein/h, I/R group; P < 0.02). Immunohistochemistry revealed that the expression of HO-1 was mainly localized to inflammatory cells. CONCLUSIONS: ALI following I/R of the lower limbs in rats is associated with an increase of pulmonary expression of HO-1, inhibition of this expression increase the severity of ALI.     

Carbon monoxide can prevent acute lung injury observed after ischemia reperfusion of the lower extremities

BACKGROUND: Pulmonary expression of heme oxygenase has been observed in multiple studies. This expression has been found beneficial in decreasing the severity of acute lung injury (ALI) post ischemia-reperfusion (I/R). The aim of this study was to assess the role of exogenous administration of the end-products of heme oxygenase reaction, carbon monoxide, and bilirubin, in the severity of ALI. STUDY DESIGN: We compared five groups of rats (n = 7/group) including a sham group and four I/R of the lower extremities by clamping the abdominal aorta for 2 h followed by reperfusion for 2 h. The four I/R groups included a control group, one pretreated with bilirubin (50 micromol/kg IV), another with inhaled carbon monoxide (CO) (250 ppm), and the last pretreated with both. The severity of ALI has been evaluated by a histological assay grading neutrophilic infiltration, as well as a study of the microvascular permeability using the Evans blue. RESULTS: The administration of CO prevented pulmonary microvascular permeability alteration noted after I/R of the lower limbs (pulmonary content of Evans blue: 141 +/- 23 microg/g of tissue in the isolated I/R group versus 68 +/- 34 microg/g of tissue in CO group; P < 0.001). Histologically CO administration inhibited neutrophilic sequestration observed after I/R. On the other hand, treatment by bilirubin alone (50 micromol/kg IV) did not modify the extent of pulmonary injury. CONCLUSION: Exogenous administration of carbon monoxide by inhalation at low doses prevented ALI post-I/R in this model.     

Endotoxin after gut ischemia/reperfusion causes irreversible lung injury.

We have recently reported that 45 min of gut ischemia causes moderate 125I-albumin lung leak at 6 hr of reperfusion which was reversed at 18 hr. Our purpose was to determine the effect of a second insult, low dose endotoxin (LPS, 2.5 mg/kg), given 6 hr after gut ischemia/reperfusion (I/R) on this lung injury as assessed by 125I-albumin leak, neutrophil influx (myeloperoxidase assay, MPO), histopathology, and mortality. Rats were randomized to either sham laparotomy (LAP) or 45 min of superior mesenteric artery occlusion and 6 hr later were treated with LPS or saline. At 18 hr reperfusion the lungs were harvested, assayed for 125I-albumin leak and MPO, and microscopically examined by an unbiased observer after routine H&E staining. We observed that LPS increased lung neutrophil levels both with or without gut I/R. However, only the combined insult (I/R + LPS) increased 125I-albumin leak at 18 hr of reperfusion. Lung histology confirmed that the sequential combination of I/R + LPS caused marked interstitial edema and neutrophil sequestration accompanied by alveolar edema, hemorrhage, and fibrinous exudate, while I/R or LAP + LPS did not. The mortality rate of I/R + LPS was 39% which was significantly higher than LAP alone (0%), gut I/R alone (0%), or LAP + LPS (4%). In conclusion, a delayed exposure to low dose endotoxin converts moderate gut I/R-induced lung dysfunction into advanced organ failure.     

肠缺血后肺内一氧化氮合酶的表达及其意义

目的　研究不同时相小肠缺血 /再灌注引起的急性肺损伤 (ALI)过程中 ,内皮型一氧化氮合酶 (eNOS)及诱导型一氧化氮合酶 (iNOS)的表达及其在ALI发生中的作用。方法　SD大鼠 ,阻断肠系膜上动脉 (SMA) 60min ,根据不同再灌注时间随机分为A(60min)、B(12 0min)、C(2 40min)组。AC、BC、CC组分别为其对照组。Evans蓝法测定大鼠肺毛细血管通透性、逆转录 聚合酶链式反应 (RT PCR)法测定肺NOSmRNA表达、Western印迹法测定肺组织NOS表达 ,同时进行小肠组织学检查以评价肠损伤程度。结果　肺漏出量随着小肠再灌注时间延长而增加 ,A/AC组 :2 2 9.82± 18.13 /198.0 0± 2 2 .17;B/BC组 :2 74.12± 2 5 .40 /178.48± 2 0 .3 7;C/CC组 :2 69.87±2 0 .93 /195 .68± 10 .99。A与B组间比较差异有显著性。组织学检查 :小肠损伤在A组、B组及C组三组间差异有显著性。肺组织iNOS表达随再灌注时间延长而逐渐增加 ,其中A、C组比较差异有显著性 ,肺组织eNOS表达各组间差异无显著性。结论　肠道缺血 /再灌注损伤 :(1)导致肺毛细血管通透性改变及微血管漏出增加 ;(2 )引起肺内iNOS表达增高 ,且与小肠再灌注时间成正比 ,与肺血管漏出成正比。提示iNOS在肠缺血 /再灌注导致的肺损伤过程中可能起重要作用     

Suppressive effect of low-level laser therapy on tracheal hyperresponsiveness and lung inflammation in rat subjected to intestinal ischemia and reperfusion

Intestinal ischemia and reperfusion (i-I/R) is an insult associated with acute respiratory distress syndrome (ARDS). It is not known if pro- and anti-inflammatory mediators in ARDS induced by i-I/R can be controlled by low-level laser therapy (LLLT). This study was designed to evaluate the effect of LLLT on tracheal cholinergic reactivity dysfunction and the release of inflammatory mediators from the lung after i-I/R. Anesthetized rats were subjected to superior mesenteric artery occlusion (45 min) and killed after clamp release and preestablished periods of intestinal reperfusion (30 min, 2 or 4 h). The LLLT (660 nm, 7.5 J/cm²) was carried out by irradiating the rats on the skin over the right upper bronchus for 15 and 30 min after initiating reperfusion and then euthanizing them 30 min, 2, or 4 h later. Lung edema was measured by the Evans blue extravasation technique, and pulmonary neutrophils were determined by myeloperoxidase (MPO) activity. Pulmonary tumor necrosis factor-α (TNF-α), interleukin-10 (IL-10), intercellular adhesion molecule-1 (ICAM-1), and isoform of NO synthase (iNOS) mRNA expression were analyzed by real-time PCR. TNF-α, IL-10, and iNOS proteins in the lung were measured by the enzyme-linked immunoassay technique. LLLT (660 nm, 7.5 J/cm²) restored the tracheal hyperresponsiveness and hyporesponsiveness in all the periods after intestinal reperfusion. Although LLLT reduced edema and MPO activity, it did not do so in all the postreperfusion periods. It was also observed with the ICAM-1 expression. In addition to reducing both TNF-α and iNOS, LLLT increased IL-10 in the lungs of animals subjected to i-I/R. The results indicate that LLLT can control the lung's inflammatory response and the airway reactivity dysfunction by simultaneously reducing both TNF-α and iNOS.     

Alpha chemokines regulate direct lung ischemia-reperfusion injury.

BACKGROUND: Alpha chemokines function predominantly to recruit and activate neutrophils, which are important effectors of acute lung injury. This study evaluated whether blockade of 2 potent alpha chemokines, macrophage inflammatory protein-2 (MIP-2) and cytokine-induced neutrophil chemoattractant (CINC), is protective against lung ischemia-reperfusion injury in a warm in situ hilar clamp model. METHODS: Left lungs of Long-Evans rats underwent normothermic ischemia for 90 minutes and reperfusion for up to 4 hours. Treated animals received antibodies to MIP-2 or CINC immediately prior to reperfusion. Lung injury was quantitated by vascular permeability to (125)I-radiolabeled bovine serum albumin, lung tissue neutrophil sequestration (myeloperoxidase [MPO] content), and alveolar leukocyte content in bronchoalveolar lavage (BAL) fluid. CINC and MIP-2 mRNA expression were assessed by northern blot, while ribonuclease protection assays were performed to evaluate mRNA expression for a number of early response cytokines. MIP-2 and CINC protein expression in injured lungs was determined by immunoblotting. RESULTS: Treatment with antibodies to CINC or MIP-2 was associated with significant protection against increases in vascular permeability, MPO content and alveolar leukocyte sequestration in injured lungs. Expression of CINC and MIP-2 mRNA peaked after 2 hours of reperfusion in injured lungs, and protein levels were evident on immunoblotting after 3 hours of reperfusion. Neither CINC nor MIP-2 blockade appeared to modulate cytokine mRNA expression. CONCLUSIONS: CINC and MIP-2 are important mediators involved in direct lung ischemia-reperfusion injury. They appear to function by modulating neutrophil recruitment, but not inflammatory cytokine release.     

Gut-derived mesenteric lymph but not portal blood increases endothelial cell permeability and promotes lung injury after hemorrhagic shock.

OBJECTIVE: To determine whether gut-derived factors leading to organ injury and increased endothelial cell permeability would be present in the mesenteric lymph at higher levels than in the portal blood of rats subjected to hemorrhagic shock. This hypothesis was tested by examining the effect of portal blood plasma and mesenteric lymph on endothelial cell monolayers and the interruption of mesenteric lymph flow on shock-induced lung injury. SUMMARY BACKGROUND DATA: The absence of detectable bacteremia or endotoxemia in the portal blood of trauma victims casts doubt on the role of the gut in the generation of multiple organ failure. Nevertheless, previous experimental work has clearly documented the connection between shock and gut injury as well as the concept of gut-induced sepsis and distant organ failure. One explanation for this apparent paradox would be that gut-derived inflammatory factors are reaching the lung and systemic circulation via the gut lymphatics rather than the portal circulation. METHODS: Human umbilical vein endothelial cell monolayers, grown in two-compartment systems, were exposed to media, sham-shock, or postshock portal blood plasma or lymph, and permeability to rhodamine (10K) was measured. Sprague-Dawley rats were subjected to 90 minutes of sham or actual shock and shock plus lymphatic division (before and after shock). Lung permeability, pulmonary myeloperoxidase levels, alveolar apoptosis, and bronchoalveolar fluid protein content were used to quantitate lung injury. RESULTS: Postshock lymph increased endothelial cell monolayer permeability but not postshock plasma, sham-shock lymph/plasma, or medium. Lymphatic division before hemorrhagic shock prevented shock-induced increases in lung permeability to Evans blue dye and alveolar apoptosis and reduced pulmonary MPO levels. In contrast, division of the mesenteric lymphatics at the end of the shock period but before reperfusion ameliorated but failed to prevent increased lung permeability, alveolar apoptosis, and MPO accumulation. CONCLUSIONS: Gut barrier failure after hemorrhagic shock may be involved in the pathogenesis of shock-induced distant organ injury via gut-derived factors carried in the mesenteric lymph rather than the portal circulation.     

Pyrrolidine dithiocarbamate prevents 60 minutes of warm mesenteric ischemia/reperfusion injury in rats

BACKGROUND: Pyrrolidine dithiocarbamate (PDTC) is a low-molecular-weight thiol antioxidant and potent inhibitor of nuclear factor-kappaB (NF-kappaB) activation. It has been shown to attenuate harmful effects of ischemia/reperfusion (I/R) injury in many organs. In recent animal studies, destructive effects of reperfusion injury has been demonstrated. In this study, we aimed to investigate whether PDTC prevents harmful effects of superior mesenteric I/R injury in rats. METHODS: Wistar-albino rats were randomly allocated into the following 4 groups: (1) sham-operated group--these animals underwent laparotomy without I/R injury (group I, n = 12); (2) sham+PDTC group--identical to sham-operated rats except for the administration of PDTC (100 mg/kg intravenous bolus) 30 minutes prior to the commencement of the experimental period (group II, n = 12); (3) I/R group--these animals underwent laparotomy and 60 minutes of ischemia followed by 120 minutes of reperfusion (group III, n = 12); (4) PDTC-treated group (100 mg/kg, intravenously, before the I/R, group IV, n = 12). All animals were killed, and intestinal tissue samples were obtained for investigation of intestinal mucosal injury, myeloperoxidase (MPO) activity, malondialdehyde (MDA) levels, glutathione (GSH) levels, and intestinal edema. RESULTS: There was a statistically significant decrease in GSH levels, along with an increase in intestinal mucosal injury scores, MPO activity, MDA levels, and intestinal tissue wet-to-dry weight ratios in group III when compared to groups I, II, and IV (P < .05). However, PDTC treatment led to a statistically significant increase in GSH levels, along with a decrease in intestinal mucosal injury scores, MPO activity, MDA levels, and intestinal tissue wet-to-dry weight ratios in group IV (P < .05). CONCLUSIONS: This study showed that PDTC treatment significantly prevented the reperfusion injury caused by superior mesenteric I/R. Further clinical studies are needed to clarify whether PDTC may be a useful therapeutic agent to use in particular operations where the reperfusion injury occurs.     

Regional effects of nafamostat, a novel potent protease and complement inhibitor, on severe necrotizing pancreatitis

BACKGROUND: We evaluated the effect of the novel protease inhibitor nafamostat on rat necrotizing pancreatitis through different routes of administration. METHODS: Three hours after the induction of severe pancreatitis, the rats received intravenous gabexate or intravenous or local mesenteric intra-arterial nafamostat. At 9 hours, ascites and bronchoalveolar lavage fluid were collected for the evaluation of capillary leakage (Evans blue extravasation). Pancreas and lung were excised for histologic features, myeloperoxidase, and trypsinogen activation peptide. Twenty-four hour survival was evaluated. RESULTS: Only the intravenous infusion of nafamostat significantly reduced myeloperoxidase (11.7 +/- 2.3 vs 18.3 +/- 1.8 mU/mg; P <.05) and capillary leakage in lungs (Evans blue dye, 1.6 +/- 0.3 vs 2.6 +/- 0.3; P <.05). Only intra-arterial infusion of nafamostat significantly diminished capillary peritoneal leakage (Evans blue dye, 3.6 +/- 0.9 vs 9.4 +/- 0.4; P <.01). Typsinogen activation peptide levels were significantly reduced in all groups, but only intra-arterial infusion did so to baseline. Histologic inflammation in the pancreas was most significantly reduced after intra-arterial infusion (0.92 +/- 0.08 vs 2.91 +/- 0.06; P <.05). No form of protease inhibition reduced mortality rates. CONCLUSIONS: The effects of protease inhibition depend on the route of administration. Nafamostat has maximal effects on the pancreas and peritoneal capillary leakage when delivered by way of local intra-arterial infusion, and shows a greater reduction of lung leukocyte infiltration and capillary leakage by the intravenous route. Nafamostat is more effective than gabexate.     

A Mac-1 antibody reduces liver and lung injury but not neutrophil sequestration after intestinal ischemia-reperfusion.

BACKGROUND. Intestinal ischemia and reperfusion (I/R) result in leukosequestration and injury to the liver and lungs. The adherence-dependent oxidative burst of neutrophils requires cell adhesion through the Mac-1 integrin. Neutrophil-mediated tissue injury may depend on this specific cell adhesion event. This study tests the effect of a Mac-1 (CD 11b) monoclonal antibody (MAb) (R17) on liver and lung injury after intestinal I/R. METHODS. After collaterals were ligated in anesthetized rats, the superior mesenteric artery was clamped for 60 minutes followed by 3 hours of reperfusion. Animals were treated with saline solution, R17, or nonspecific immunoglobulin M. Another nonischemic group of rats were sham controls. Lung and intestinal polymorphonuclear leukocyte sequestration was assessed by measurement of myeloperoxidase and lung permeability by bronchoalveolar lavage blood concentration ratio of 125I-labeled bovine serum albumin. RESULTS. At 3 hours of reperfusion lung and intestinal myeloperoxidase and lung permeability were increased. Treatment with R17 MAb did not reduce intestinal or lung myeloperoxidase but prevented increased lung permeability. Similarly, after treatment with saline solution, liver polymorphonuclear leukocyte sequestration increased after 3 hours of reperfusion, and serum alanine aminotransferase level rose eightfold. R17 MAb did not significantly reduce liver neutrophil sequestration; however, it reduced alanine aminotransferase level more than 50% when compared to saline solution controls. At 3 hours of reperfusion there was a leukocytosis (white blood cell count, 14.9 +/- 1.0 x 10(3)/mm3 vs 6.0 +/- 0.8 in sham [p less than 0.05]). The white blood cell count was unaffected by R17 MAb. CONCLUSIONS. These data indicate that a MAb to the neutrophil Mac-1 integrin reduces lung and liver injury after intestinal I/R but does not reduce lung or intestinal leukosequestration.     

Intestinal ischemia and reperfusion impairs vasomotor functions of pulmonary vascular bed

OBJECTIVE: To investigate the effects of intestinal ischemia and reperfusion (I/R) on the pulmonary vascular endothelium and smooth muscle. SUMMARY BACKGROUND DATA: Respiratory failure is an important cause of death and complications after intestinal I/R. Although the mechanism of respiratory failure in this setting is complex and poorly understood, recent studies of lung injury suggest that endothelial dysfunction may play a significant role. METHODS: A rat model of acute lung injury was studied after 60 minutes of superior mesenteric arterial occlusion followed by either 120 or 240 minutes of reperfusion. The pulmonary vasomotor function was examined in isolated lungs perfused at a constant flow rate. RESULTS: Sixty minutes of intestinal ischemia followed by 120 or 240 minutes of reperfusion led to a significant reduction in the ability of the pulmonary vasculature to respond to angiotensin II, acetylcholine, and calcium ionophore but not to nitroglycerin. The vasoconstriction response to N(G)-nitro-L-arginine methyl ester, which is a measure of basal nitric oxide release, was diminished in the 240-minute reperfusion group. Intestinal I/R was also associated with pulmonary leukosequestration and increased pulmonary microvascular leakage. CONCLUSIONS: Basal and agonist-stimulated release of nitric oxide from the pulmonary vascular endothelium and the ability of pulmonary smooth muscle to contract in response to angiotensin II were impaired by intestinal I/R. Such functional impairment in both pulmonary vascular endothelium and smooth muscle may contribute to the alveolocapillary dysfunction and pulmonary hypertension found in acute lung injury after intestinal I/R.     

Effective treatment of gut barrier dysfunction using an antioxidant,a PAF inhibitor,and monoclonal antibodies against the adhesion molecule PECAM-1

BACKGROUND: Oxygen free radicals (OFRs), platelet activating factor (PAF), cell adhesion molecules, and transmigration of polymorphonuclear leukocytes through the gut barrier are probably all essential in the development of gut barrier dysfunction following intestinal ischemia and reperfusion (I/R). Pretreatment and early treatment of I/R with the OFRs-scavenger (NAC), the PAF inhibitor lexipafant, and monoclonal antibodies against the adhesion molecule PECAM-1 (anti-PECAM-1-Mab) have been reported to be effective in the prevention or recovery of gut barrier dysfunction and result in a decrease in cytokine levels. Less is known about the effect of treatment inserted during the late stage of I/R. The objective of this study was to evaluate the potential therapeutic value of single or combination therapy with NAC, lexipafant, and anti-PECAM-1-MAb administered late during intestinal I/R in the rat. METHODS: NAC, lexipafant, and anti-PECAM-1-MAb were administrated, alone or in combination, after 3 h of reperfusion following 40 min of superior mesenteric arterial ischemia in the rat. Intestinal endothelial and epithelial barrier permeability, myeloperoxidase (MPO) activity, interleukin-1 beta (IL-1 beta), and protease inhibitor levels were evaluated after 12 h of reperfusion. RESULTS: Intestinal endothelial and epithelial permeability significantly increased in rats with I/R and saline treatment. Proteolytic activity in plasma was indicated by low levels of the three measured plasma protease inhibitors. Intestinal mucosal MPO content increased significantly. These changes were, to different degrees, reduced by late inserted treatment with NAC, lexipafant, or anti-PECAM-1-MAb. Alterations in systemic levels of IL-1 beta paralleled the changes found in gut barrier permeability and leukocyte trapping. Systemic antithrombin III levels and increased barrier permeability in remote organs were partly restored, especially by multimodal therapy. CONCLUSION: Treatment with NAC, lexipafant, and/or monoclonal antibodies against PECAM-1, inserted at a later stage of I/R, reduced the severity of I/R-associated intestinal dysfunction and decreased the systemic concentrations of IL-1 beta, local leukocyte recruitment (MPO), and partly restored plasma protease inhibitor levels.     

Hyperoxygenated solution preconditioning attenuates lung injury induced by intestinal ischemia reperfusion in rabbits

BACKGROUND: The current study was undertaken to elucidate the possible therapeutic effects of hyperoxygenated solution (HOS) preconditioning on lung injury induced by intestinal ischemia/reperfusion (I/R) in rabbits. MATERIALS AND METHODS: Eighty rabbits were randomly divided into four groups (n = 20 each) as follows: (1) control group in which sham operation was performed (sham group), (2) HOS pretreatment group and sham operation (HOS + sham group), (3) ischemia/reperfusion group (I/R group), (4) HOS pretreatment and ischemia/reperfusion group (HOS + I/R group). Intestinal I/R model was produced by clamping superior mesenteric artery with an atraumatic vascular clamp for 1 h, and followed by reperfusion for 2 h. Animals in HOS + sham group and HOS + I/R group received intravenous HOS infusion (20 mL/kg, 10 mL/kg.h for 2 h) every day for 5 d before operation, and animals in sham group and I/R group received the same amount of normal saline in the same way. At the end of reperfusion, 8 animals from every group were sacrificed and histopathological changes of lung were observed; pulmonary edema, lung myeloperoxidase activity, superoxide dismutase activity, and malondialdehyde levels in lung tissues were also detected. The rest 12 animals in every group underwent 60 min of intestinal ischemia followed by 72 h of reperfusion, and effects of HOS pretreatment on survival in rabbits with lung injury induced by intestinal I/R was observed. RESULTS: When rabbits were subjected to 60 min of intestinal ischemia, a high incidence of mortality was observed within 24 h. In this situation, HOS preconditioning before the start of ischemia/reperfusion significantly reduced the mortality. HOS preconditioning also decreased lung wet/dry ratio, neutrophil infiltration, lipid membrane peroxidation, and increased superoxide dismutase activity in the lungs after intestinal I/R compared with the I/R-treated rabbit lungs without HOS treatment. Histopathological analysis also indicated the effectiveness of HOS pretreatment. CONCLUSIONS: HOS preconditioning could preserve superoxide dismutase activity, decrease lipid membrane peroxidation and neutrophil infiltration in the lungs, then ameliorate the deleterious changes in pulmonary injury induced by intestinal I/R.     

Pancreatic enzymes in the gut contributing to lung injury after trauma／hemorrhagic shock

Objective: To examine whether pancreatic proteolytic enzymes involve in lung injury induced by trauma/hemorrhagic shock (T/HS). Methods: Male Sprague-Dawley rats received intraluminal or intravenous pancreatic serine protease inhibitor, 6-amidino-2-naphthyl p-guanidinobenzoate dimethanesulfate (ANGD) during laparotomy (trauma), and were subjected to 90 minutes of T/HS or trauma-sham shock (T/SS). Degree of lung injury was assessed 3 hours after resuscitation with Ringer‘s lactate solution. Results: Lung permeability, pulmonary myeloperoxidase levels and the ratio of bronchoalveolar lavage fluid protein to plasma protein increased after T/HS, and significantly decreased in intraluminal-ANGD treated but not in intravenous-ANGD treated rats. Histological analysis demonstrated fewer injured villi in the intraluminal-ANGD treated rats compared with those in the control rats. Linear regression analysis revealed that the percentage of injured ileal mucosal villi directly related to pulmonary polymorphic neutrophil sequestration and lung permeability to Evans blue dye. Conclusions: Pancreatic proteolytic enzymes in the ischemic gut may be important toxic factors contributing to lnng injury after T/HS.