Inhibition of matrix metalloproteinases reduces local and distant organ injury following experimental acute pancreatitis

BACKGROUND: Pulmonary complications from pancreatitis involve parenchymal destruction via proteolytic enzymes. Matrix metalloproteinases (MMPs) may play an important role in pulmonary injury following acute severe pancreatitis. We hypothesized that local and distant organ injury would be decreased by the presence of an MMP inhibitor (Batimistat; BB-94) following severe acute pancreatitis (AP). METHODS: Eighteen male rats were randomized into two groups: BB-94 (AP + 40 mg/kg/24 h BB-94 ip x three doses) or control (AP + 20 ml/kg/24 h normal saline ip x three doses). Necrotizing AP was induced by retrograde infusion of 5% sodium taurocholate (1.5 ml/kg) into the pancreatic duct. Twenty additional animals were randomized into BB-94 and control groups for the survival study. Serum was evaluated for amylase and MMP activity. Pancreatic sections were graded for edema, necrosis, neutrophil infiltrate, and hemorrhage. Myloperoxidase (MPO) activity was used to determine PMN infiltration in the lung. Evan's Blue dye extravasation was used to quantify vascular permeability. RESULTS: Animals in the BB-94 group had decreased amylase levels (1086.0 +/- 61.7 U/L vs 2232.7 +/- 309.9 U/L; P < 0.05), decreased cellular infiltrate (1.4 +/- 0.2 vs 2.3 +/- 0.2; P < 0.02), and decreased necrosis (4.1 +/- 0.3 vs 6.1 +/- 0.4; P < 0.005) compared to the control group. Lung tissue following pancreatitis in the BB-94 group demonstrated decreased MPO activity (41.5 +/- 2.4 units vs 57.3 +/- 2.9 units; P < 0.05) and decreased vascular permeability (18.3 +/- 2.8 mg/100 g vs 30.1 +/- 4.6 mg/100 g; P < 0.05). Animals treated with BB-94 had 100% survival compared to 50% survival in control at 72 h. CONCLUSIONS: Pancreatitis results in increased local and distant MMP activity. Pulmonary and pancreatic injury following AP can be abrogated by treatment with an MMP inhibitor (Batimistat; BB-94) which may result in decreased morbidity and mortality.     

Blocking of endogenous nitric oxide increases white blood cell accumulation in rat lung

Background/Purpose

Nitric oxide (NO) is a known selective dilator of the pulmonary vascular tree. There also is evidence that it plays a role in diminishing neutrophil adherence to vascular endothelial cells. An understanding of these effects of NO on the pulmonary microcirculation is essential to our understanding of its mechanisms of action as well as its potential as a therapeutic agent to reduce neutrophil sequestration and subsequent lung injury and inflammation from a variety of conditions. This study examines the direct effects of inhibition of endogenous NO synthesis with the l-arginine analog, Nω-nitro-l-arginine methyl ester (l-NAME) on neutrophil accumulation within the lung.

Methods

Lung samples from 2 groups of rats (n = 14 for each study group) were studied. One group was given an intravenous infusion of l-NAME, and the other received normal saline (NS), at 2 mg/kg/min for 1 hour. The accumulation of neutrophils within the lungs was assessed quantitatively by myeloperoxidase (MPO) assay as well as by microscopic examination by a pathologist blinded to the 2 groups.

Results

The l-NAME group showed increased MPO activity in the lung compared with the NS group (mean MPO/mean bicinchoninic acid [BCA]: 43.46 ± 3.10 U/μg v 23.58 ± 2.48 U/μg; mean MPO/g wet lung [gwl]: 57.60 ± 5.98 U/gwl v 27.10 ± 3.84 U/gwl, mean ± SEM; P < .05). Histologic examination (n = 6 each group) showed 26 ± 2 neutrophils/5 hpf for the l-NAME group versus 18 ± 1 neutrophils/5 hpf for the NS group (P < 0.05).

Conclusions

These data indicate that the inhibition of endogenous NO has a direct effect of increasing neutrophil sequestration in the pulmonary vasculature and alveoli. This suggests that endogenous NO plays a critical role in the control of neutrophil-endothelial cell interactions in the lung.     

Myeloperoxidase activity as a lung injury marker in the lamb model of congenital diaphragmatic hernia

PURPOSE: The antioxidant system is the primary intracellular defense system of the lung against oxygen toxicity (neutrophil sequestration). The CDH lamb model antioxidant system is deficient. It is hypothesized that pulmonary neutrophil sequestration may play a part in the acute lung injury of CDH patients. Myeloperoxidase (MPO) is a major constituent of neutrophil cytoplasmic granules and its activity therefore is a direct measure of neutrophil presence and an indirect indicator of lung injury. METHODS: Eight lambs had left-sided diaphragmatic hernias surgically created at 80 days' gestation and were delivered by cesarean section at 140 to 145 days. Eight littermate lambs served as controls. Lambs were either killed before ventilation or were ventilated conventionally for 4 hours with 100% O(2) and then killed. The lungs were dissected en bloc and snap frozen. The samples were homogenized, sonicated, freeze-thawed, and separated by density centrifugation. Supernatants were analyzed for myeloperoxidase (MPO) activity by spectrophotometry with o-dianisidine dihydrochloride and hydrogen peroxide at 460 nm. The MPO activity was normalized to the protein content of the supernatant and expressed as units of MPO activity per milligram of protein. RESULTS: There was significantly more MPO activity in the CDH-ventilated lungs than controls similarly ventilated (3,203 +/- 665 versus 1,220 +/- 194, P =.001). There was no difference in MPO activity between the CDH and control lungs (318 +/- 57 v 348 +/- 61; P =.5). There was no difference between right and left lungs in any group. CONCLUSION: Ventilation and hyperoxia leads to neutrophil accumulation in lung tissue, which is most pronounced in the CDH lung tissue. This is a further clue to the pathophysiology of iatrogenic lung injury in CDH. The myeloperoxidase assay may now be used to evaluate antenatal or postnatal antioxidant therapies for iatrogenic lung injury in CDH.     

Cardiotrophin-1 is a prophylactic against the development of chronic hypoxic pulmonary hypertension in rats

BACKGROUND: Cardiotrophin-1 (CT-1) reduces arterial blood pressure by activating nitric oxide synthesis. This study attempted to elucidate the effect of CT-1 on pulmonary arteries of pulmonary hypertensive rats. METHODS: Pulmonary hypertension was induced in rats in a hypoxic chamber containing 10% to 11% oxygen. Rats kept in the hypoxic environment received either recombinant mouse CT-1 at a concentration of 50 micro g/kg (CT-1+hypoxia group, n = 21) or phosphate-buffered saline (hypoxia group, n = 30) once per day. Control rats housed in room air also received either the equivalent concentration of CT-1 (CT-1+normoxia group, n = 18) or phosphate-buffered saline (normoxia group, n = 39). Pulmonary arterial pressure, pulmonary vasorelaxation, and ventricular hypertrophy were measured. RESULTS: The mean pulmonary arterial pressures were as follows (from lowest to highest; p values are relative to the hypoxia group): normoxia group (20.3 +/- 4.0 mm Hg, p < 0.0001), CT-1+normoxia group (21.1 +/- 2.4 mm Hg, p < 0.0001), CT-1+hypoxia group (27.9 +/- 4.1 mm Hg, p = 0.0019), and hypoxia group (33.9 +/- 6.6 mm Hg). The endothelium-dependent vasorelaxation value was largest in the normoxia group (59.5% +/- 17.4%, p < 0.0001), with it decreasing in the other groups in the following order (p values are relative to the hypoxia group): CT-1+normoxia group (52.8% +/- 15.5%, p = 0.0005), CT-1+hypoxia group (42.3% +/- 14.8%, p = 0.0061), and hypoxia group (17.4% +/- 4.8%). Right ventricular hypertrophy was significant only in the hypoxia group. CONCLUSIONS: Our results demonstrate that treatment with CT-1 in a chronic hypoxic pulmonary hypertension model protects the endothelial function of the pulmonary artery; decreases pulmonary arterial pressure; and attenuates right ventricular hypertrophy.     

Metalloproteinase inhibition prevents acute respiratory distress syndrome

BACKGROUND: The acute respiratory distress syndrome (ARDS) occurs in patients with clearly identifiable risk factors, and its treatment remains merely supportive. We postulated that patients at risk for ARDS can be protected against lung injury by a prophylactic treatment strategy that targets neutrophil-derived proteases. We hypothesized that a chemically modified tetracycline 3 (COL-3), a potent inhibitor of neutrophil matrix metalloproteinases (MMPs) and neutrophil elastase (NE) with minimal toxicity, would prevent ARDS in our porcine endotoxin-induced ARDS model. METHODS: Yorkshire pigs were anesthetized, intubated, surgically instrumented for hemodynamic monitoring, and randomized into three groups: (1) control (n = 4), surgical instrumentation only; (2) lipopolysaccharide (LPS) (n = 4), infusion of Escherichia coli lipopolysaccharide at 100 microg/kg; and (3) COL-3 + LPS (n = 5), ingestion of COL-3 (100 mg/kg) 12 h before LPS infusion. All animals were monitored for 6 h following LPS or sham LPS infusion. Serial bronchoalveolar lavage (BAL) samples were analyzed for MMP concentration by gelatin zymography. Lung tissue was fixed for morphometric assessment at necropsy. RESULTS: LPS infusion was marked by significant (P < 0.05) physiological deterioration as compared with the control group, including increased plateau airway pressure (P(plat)) (control = 15.7 +/- 0.4 mm Hg, LPS = 23.0 +/- 1.5 mm Hg) and a decrement in arterial oxygen partial pressure (P(a)O(2)) (LPS = 66 +/- 15 mm Hg, Control = 263 +/- 25 mm Hg) 6 h following LPS or sham LPS infusion, respectively. Pretreatment with COL-3 reduced the above pathophysiological changes 6 h following LPS infusion (P(plat) = 18.5 +/- 1.7 mm Hg, P(a)O(2) = 199 +/- 35 mm Hg; P = NS vs control). MMP-9 and MMP-2 concentration in BAL fluid was significantly increased between 2 and 4 h post-LPS infusion; COL-3 reduced the increase in MMP-9 and MMP-2 concentration at all time periods. Morphometrically LPS caused a significant sequestration of neutrophils and monocytes into pulmonary tissue. Pretreatment with COL-3 ameliorated this response. The wet/dry lung weight ratio was significantly greater (P < 0.05) in the LPS group (10.1 +/- 1.0 ratio) than in either the control (6.4 +/- 0.5 ratio) or LPS+COL-3 (7.4 +/- 0.6 ratio) group. CONCLUSIONS: A single prophylactic treatment with COL-3 prevented lung injury in our model of endotoxin-induced ARDS. The proposed mechanism of COL-3 is a synergistic inhibition of the terminal neutrophil effectors MMPs and NE. Similar to the universal practice of prophylaxis against gastric stress ulceration and deep venous thromboses in trauma patients, chemically modified tetracyclines may likewise be administered to prevent acute lung injury in critically injured patients at risk of developing ARDS.     

Pancreatitis-induced acute lung injury. An ARDS model.

Cerulein-induced acute pancreatitis in rats is associated with acute lung injury characterized by increased pulmonary microvascular permeability, increased wet lung weights, and histologic features of alveolar capillary endothelial cell and pulmonary parenchymal injury. The alveolar capillary permeability index is increased 1.8-fold after a 3-hour injury (0.30 to 0.54, p less than 0.05). Gravimetric analysis shows a similar 1.5-fold increase in wet lung weights at 3 hours (0.35% vs. 0.51% of total body weight, p less than 0.05). Histologic features assessed by quantitative morphometric analysis include significant intra-alveolar hemorrhage (0.57 +/- 0.08 vs. 0.12 +/- 0.02 RBC/alveolus at 6 hours, p less than 0.001); endothelial cell disruption (28.11% vs. 4.3%, p less than 0.001); and marked, early neutrophil infiltration (7.45 +/- 0.53 vs. 0.83 +/- 0.18 PMN/hpf at 3 hours, p less than 0.001). The cerulein peptide itself, a cholecystokinin (CCK) analog, is naturally occurring and is not toxic and in several in vitro settings including exposure to pulmonary artery endothelial cells, Type II epithelial cells, and an ex vivo perfused lung preparation. The occurrence of this ARDS-like acute lung injury with acute pancreatitis provides an excellent experimental model to investigate mechanisms and mediators involved in the pathogenesis of ARDS.     

Selective inducible nitric oxide synthase (iNOS) inhibition attenuates remote acute lung injury in a model of ruptured abdominal aortic aneurysm

OBJECTIVE: Abdominal aortic aneurysm rupture is associated with a systemic inflammatory response syndrome and acute lung injury. Using a selective inducible nitric oxide synthase (iNOS) inhibitor, N(6)-(iminoethyl)-lysine (L-NIL), we explored the role of iNOS in the early pro-inflammatory signaling and acute lung injury in experimental abdominal aortic aneurysm rupture. MATERIALS AND METHODS: Anesthetized rats were randomized to sham control or shock and clamp (s + c) groups, which underwent one hour of hemorrhagic shock, followed by 45 minutes of supramesenteric aortic clamping, and then two hours resuscitated reperfusion. Animals in s + c were randomized to receive intravenous L-NIL at 50 microg/kg/h or saline at the start of reperfusion. Pulmonary permeability to (125)I-labeled albumin, myeloperoxidase (MPO) activity, cytokine levels, and semi-quantitative RT-PCR for mRNA were indicators of microvascular permeability, leuco-sequestration, and pro-inflammatory signaling, respectively. RESULTS: Lung permeability index were significantly increased in s + c compared to sham (4.43 +/- 0.96 versus 1.30 +/- 0.17, P < 0.01), and attenuated by L-NIL treatment (2.14 +/- 0.70, P < 0.05). Lung tissue MPO activity was significantly increased in s + c compared to sham (2.80 +/- 0.32 versus 1.03 +/- 0.29, P < 0.002), and attenuated by L-NIL treatment (1.50 +/- 0.20, P < 0.007). Lung tissue iNOS activity was significantly increased in s + c compared to sham animals (P < 0.05), and attenuated by L-NIL treatment (P < 0.05). Lung tissue iNOS mRNA was upregulated 8-fold in s + c compared to sham (P < 0.05). Data represents mean +/- standard error mean, comparisons with ANOVA. CONCLUSIONS: These data suggest that in our model of ruptured abdominal aortic aneurysm iNOS plays a crucial role in reperfusion lung injury. Selective inhibition of iNOS during early reperfusion prevents neutrophil mediated acute lung injury.     

内毒素性肺损伤外周血中性粒细胞CD11b表达的意义

目的：探讨内毒素血症大鼠外周血中性粒细胞（PMN）表面CD11b表达与内毒素性肺损伤的关系。方法：大肠杆菌E-Coli O111B4 4mg／kg尾静脉注射制备大鼠内毒素血症动物模型。112只大鼠随机分为对照组（静脉注射等量生理盐水）及内毒素注射后1h组、2h组、4h组、8h组、12h组、24h组,每组16只动物。在相应时间点放血处死动物,分别取股静脉血、肺组织及进行支气管肺泡灌洗,测定肺组织湿／干重（W／D）比值、肺组织髓过氧化物酶（MPO）活性和支气管肺泡灌洗液（BALF）总蛋白定量等肺损伤指标。流式细胞仪测定外周血PMN表面CD11b表达。另取16只大鼠,内毒素注射后2h时测定外周血PMN表面CD11b表达,24h时放血处死,测定上述指标。结果：①大鼠内毒素血症可以造成明显的急性肺损伤,表现为肺组织W／D比值、MPO活性和BALF总蛋白明显增高,分别在2h、8h和2h显著高于对照组（P〈0．05或P〈0．01）,峰值分别出现在内毒素注射后12h、24h和12h;②大鼠内毒素性肺损伤时,外周血PMN表面CD11b表达水平在早期（1h）明显升高（与对照组比较,P〈O．05）,在2h达到峰值,之后逐渐降低;③外周血CD11b表达峰值明显早于肺组织W／D比、MPO和BALF总蛋白等肺损伤指标的峰值出现时间;④同一动物2h时外周血PMN表面CD11b的表达水平与其24h时肺组织W／D比、MPO和BALF总蛋白含量呈显著正相关（r分别为0．78、0．77和0．73,P〈0．05）。结论：内毒素性肺损伤中,外周血CD11b表达升高可能有助于内毒素性肺损伤的早期诊断,并可能预示以后的肺损伤程度。     

Systemic thermal injury in anesthetized rabbits causes early pulmonary vascular injury that is not ablated by lazaroids

PURPOSE: To study the effects of a systemic thermal injury on the pulmonary vasculature with and without inhibitors of lipid peroxidation (U74389G). METHODS: In a prospective, placebo control, randomized, and blinded multi-group study, burn shock was induced by scalding thermal injury (65C) to 35% body surface area in rabbits (n = 28). Hemodynamics and gas exchange were followed for 240 min post burn in four groups: No Burn, Burn-Control, Burn-U74 (10 mg.Kg-1 U74389G), No Burn-U74 (10 mg.Kg-1 U74389G). RESULTS: Scald resulted in early pulmonary injury as measured by increased pulmonary vascular resistance in the pooled Burn group compared with the No Burn groups (942 +/- 358 vs 605 +/- 255 dynes.sec-1.cm-5 respectively, P < 0.05). These pulmonary changes were associated with alveolar sequestration of leukocytes (4.8 +/- 2.9 vs 17.7 +/- 6.0 cells x 10(9).L-1, P < 0.05) in the No Burn and Burn groups respectively. Histological evidence of decreased neutrophil sequestration after scald injury was present in U74 treated animals (3+ vs 2+, P < 0.05 in the Burn and No Burn groups respectively and 2+ vs 2+, P > 0.05 in the Burn-U74 and No Burn-U74 groups respectively) although bronchial alveolar lavage still demonstrated neutrophil sequestration (5.3 +/- 2.5 vs 12.2 +/- 3.3 cell 10(9).L-1, P < 0.05 in No Burn-U74 and Burn-U74 groups respectively). Similarly, circulating white blood cells were increased in the Burn group but not Burn-U74 group four hours post burn. The increase in pulmonary vascular resistance after burn was not altered by administration of U74. CONCLUSIONS: Systemic burn results in early pulmonary vascular changes associated with leukocyte sequestration. After scald injury administration of lazaroids (U744389G) did not lessen pulmonary vascular resistance changes but did reduce neutrophil sequestration.     

The nitric oxide synthase cofactor tetrahydrobiopterin reduces allograft ischemia-reperfusion injury after lung transplantation.

OBJECTIVE: Exogenous nitric oxide reduces ischemia-reperfusion injury after solid organ transplantation. Tetrahydrobiopterin, an essential cofactor for nitric oxide synthases, may restore impaired endothelium-dependent nitric oxide synthesis. We evaluated whether tetrahydrobiopterin administration to the recipient attenuates lung reperfusion injury after transplantation in swine. METHODS: Unilateral left lung transplantation was performed in 15 weight-matched pigs (24-31 kg). Donor lungs were flushed with 1.5 L cold (1 degrees C) low-potassium-dextran solution and preserved for 20 hours. Group I animals served as controls. Group II and III animals were treated with a bolus of tetrahydrobiopterin (20 mg/kg). In addition, in group III a continuous infusion of tetrahydrobiopterin (10 mg/kg per hour over 5 hours) was given. One hour after reperfusion, the recipient right lung was occluded. Cyclic guanosine monophosphate levels were measured in the pulmonary venous and central venous blood. Extravascular lung water index, hemodynamic variables, lipid peroxidation, and neutrophil migration to the allograft were assessed. RESULTS: In group III a significant reduction of extravascular lung water was noted in comparison with the controls (P =.0047). Lipid peroxidation in lung allograft tissue was significantly reduced in group II (P =.0021) and group III ( P =. 0077) in comparison with group I. Pulmonary venous levels of cyclic guanosine monophosphate increased up to 23 +/- 1 pmol/mL at 5 hours in group II and up to 40 +/- 1 pmol/mL in group III (group I, 4.1 +/- 0.5 pmol/mL [I vs III]; P <.001), whereas central venous levels of cyclic guanosine monophosphate were unchanged in all groups. CONCLUSION: Tetrahydrobiopterin administration during lung allograft reperfusion may reduce posttransplantation lung edema and oxygen-derived free radical injury in the graft. This effect is mediated by local enhancement of the nitric oxide/cyclic guanosine monophosphate pathway.     

姜黄素预先给药对内毒素诱导大鼠急性肺损伤的作用

目的 研究姜黄素预先给药对内毒素诱导大鼠急性肺损伤的作用及其可能机制。方法 48只雄性Wistar大鼠，随机分为4组（n=12），对照组（S组）、姜黄素组（C组）分别静脉注射10％二甲基亚砜（DMSO）2 ml／kg、姜黄素40 mg／kg（溶于DMSO），30 min后静脉注射生理盐水2 ml／kg;内毒素组（L组）、姜黄素预先给药组（C-L组）分别静脉注射10％DMSO 2 ml／kg、姜黄素40 mg／kg，30 min后静脉注射脂多糖（LPS）6 mg／kg。注射LPS后4 h处死动物。每组中6只大鼠在处死前15 min静脉注射伊文思蓝（EB）20mg／kg，用于测定肺组织EB含量，每组的其余大鼠用于测定支气管肺泡灌洗液（BALF）中髓过氧化物酶（MPO）活性和中性粒细胞（PMN）计数及肺组织湿干重比（W／D）、MPO活性、PMN趋化因子-1（CINC-1）mRNA、CINC蛋白表达，并在光镜下观察肺组织病理学改变。结果 与S组比较，L组BALF中MPO、PMN计数和肺组织W／D、EB及MPO、CINC-1 mRNA、CINC蛋白水平升高（P〈0．05或0．01），C组上述指标差异均无统计学意义（P〉0．05）;与L组比较，C-L组上述指标均降低（P〈0．05或0．01）。C-L组肺组织病理学损伤较L组减轻。结论 姜黄素40mg／kg预先给药对内毒素诱导急性肺损伤大鼠肺产生一定的保护作用，与下调肺组织CINC-1的表达进而抑制PMN在肺组织的聚集、激活有关。     

Prevention of acute lung injury in swine: depletion of pulmonary intravascular macrophages using liposomal clodronate

BACKGROUND: Swine contain large numbers of pulmonary intravascular macrophages (PIMs) that mediate the physiological response observed in acute lung injury (ALI). As the hyperacute dysfunction observed in pulmonary xenotransplantation is similar to endotoxin-induced ALI, PIMs may play a critical role in pulmonary xenograft dysfunction. We used liposomal clodronate to eliminate the PIM population in a model of acute swine lung injury. MATERIALS AND METHODS: Experimental swine (n = 6) received liposomal clodronate (1.25 g/10 kg) and control swine (n = 5) received saline containing liposomes before infusion of lipopolysaccharide (450 ng/kg). RESULTS: Control swine demonstrated higher peak pulmonary artery pressures (41.8 +/- 2.2 versus 16.8 +/- 1.2 mm Hg; P < 0.0001) and higher peak pulmonary vascular resistances (1405 +/- 209 versus 353 +/- 81 dynes. s. cm(-5); P = 0.0016) in response to lipopolysaccharide infusion. Clodronate treated swine also had significantly lower serum levels of tumor necrosis factor-alpha, interleukin-6, and thrombin. CONCLUSIONS: Liposomal clodronate effectively attenuates acute swine lung injury induced by endotoxin. This method of depletion of the PIM population presents a promising new treatment of swine lungs before xenotransplantation.     

Continuous venovenous hemofiltration improves arterial oxygenation in endotoxin-induced lung injury in pigs

BACKGROUND: Hypoxemia is common in septic acute lung failure. Therapy is mainly supportive, and most trials using specific inhibitors of key inflammatory mediators (ie., tumor necrosis factor alpha, interleukin 1) have failed to prove beneficial. The authors investigated if a nonspecific blood purification technique, using zero-balanced high-volume continuous venovenous hemofiltration (CWH), might improve arterial oxygenation in a fluid-resuscitated porcine model of endotoxin-induced acute lung injury. METHODS: Piglets of both sexes weighing 25-30 kg were anesthetized and mechanically ventilated. After baseline measurements, animals received an intravenous infusion of 0.5 mg/kg endotoxin (Escherichia coli lipopolysaccharide). One hour after endotoxin, animals were randomly assigned to either treatment with CWH (endotoxin + hemofiltration, n = 6) or spontaneous course (endotoxin, n = 6). At 4 h after randomization, animals were killed. Hemofiltration was performed from femoral vein to femoral vein using a standard circuit with an EF60 polysulphone hemofilter. RESULTS: Endotoxin challenge induced arterial hypoxemia, an increase in peak inspiratory pressure, pulmonary hypertension, and systemic hypotension. Treatment with CWH did not improve systemic or pulmonary hemodynamics. However, arterial oxygenation was increased in endotoxin-challenged animals at 5 h after completion of endotoxin infusion, as compared with animals not receiving CVVH (arterialoxygen tension, 268+/-33 vs. 176+/-67 mm/Hg, respectively, P < 0.01). In addition, treatment with CWH attenuated the endotoxin-induced increase in peak inspiratory pressure and increased lung compliance. CONCLUSION: These results suggest that nonspecific blood purification with high-volume CWH improves arterial oxygenation and lung function in endotoxin-induced acute lung injury in pigs, independent of improved hemodynamics, fluid removal, or body temperature.     

Mesenteric lymph is responsible for post-hemorrhagic shock systemic neutrophil priming.

BACKGROUND: Hemorrhagic shock-induced splanchnic hypoperfusion has been implicated as a priming event in the two event model of multiple organ failure (MOF). We have previously shown that early postinjury neutrophil (PMN) priming identifies the injured patient at risk for MOF. Recent in vitro studies have demonstrated that postshock mesenteric lymph primes isolated human neutrophils. We hypothesize that lymphatic diversion before hemorrhagic shock abrogates systemic PMN priming and subsequent lung injury. METHODS: Sprague-Dawley rats (n >or= 5 per group) underwent hemorrhagic shock (MAP 40 mm Hg x 30 min) and resuscitation (shed blood + 2x crystalloid) with and without mesenteric lymphatic duct diversion. Sham animals underwent anesthesia and laparotomy. Whole blood was taken 2 hours after resuscitation, heparinized, and incubated for 5 min at 37 degrees C. Surface expression of CD11b (a marker for PMN priming) was determined by flow-cytometry compared with isotype controls. In addition, lung myeloperoxidase (MPO) was measured for PMN sequestration, and Evans blue lung leak was assessed in the bronchoalveolar lavage fluid in sham, and shock +/- lymph diversion animals. RESULTS: Hemorrhagic shock resulted in increased surface expression of PMN CD11b relative to sham (23.8 +/- 6.7 vs. 9.9 +/- 0.6). Mesenteric lymphatic diversion before hemorrhagic shock abrogated this effect (8.0 +/- 2.6). Lung PMN accumulation, as assessed by MPO, was greater in the lungs of nondiverted (113 +/- 14 MPO/mg lung) versus sham (55 +/- 4 MPO/mg lung, p < 0.05); lymph diversion reduced lung PMNs to control levels (71 +/- 6.5 MPO/mg lung, p < 0.05). Evans blue lung leak was 1.6 times sham in the hemorrhagic shock group; this was returned to sham levels after lymph diversion (p < 0.05). CONCLUSION: Post-hemorrhagic shock mesenteric lymph primes circulating PMNs, promotes lung PMN accumulation, and provokes acute lung injury. Lymphatic diversion abrogates these pathologic events. These observations further implicate the central role of mesenteric lymph in hemorrhagic shock-induced lung injury. Characterizing the PMN priming agents could provide insight into the pathogenesis of postinjury MOF and ultimately new therapeutic strategies.     

8-Br-cyclic GMP given during reperfusion improves post-transplant lung edema and free radical injury.

Substitution of the NO-pathway reduces ischemia/reperfusion injury following lung transplantation. 8-Br-cGMP is a membrane permeable analogue of cGMP, the second messenger of NO. In this study the effect of continuous administration of 8-Br-cGMP on early graft function was evaluated. METHODS: Unilateral left lung transplantation was performed in 10 weight-matched pigs (23-30 kg). Donor lungs were flushed with 1.51 cold (1 degree C) LPD solution and preserved for 20 hours. In Group I (n = 5), 8-Br-cGMP (0.2 mg/kg/h) was given continuously over the entire observation time starting 15 min before reperfusion. Group II served as control, no 8-Br-cGMP was administered. In both groups, 250 microg PGE1 was injected into the pulmonary artery (PA) before flush. One hour after reperfusion the recipients contralateral right PA and bronchus were ligated to assess isolated graft function only. Extravascular lung water index (EVLWI), pulmonary vascular resistance, mean PA pressure, mean systemic arterial pressure and gas exchange were assessed during a 5-hour observation period. Lipid peroxidation as indicator for free radical mediated injury and neutrophil migration to the allograft were measured at the end of the assessment. RESULTS: EVLWI was significantly reduced in animals treated with 8-Br-cGMP (overall difference P = 0.024) with a peak 2 hours after reperfusion (Group I, 8.2+/-0.3 mg/ml vs Group II, 10.1+/-0.6 mg/ml; P = 0.039). Also in Group I the free radical mediated tissue injury was significantly lower when compared to Group II (Group I, 61.8+/-12.3 pmol/g vs Group II, 120.7+/-7.2 pmol/g; P = 0.006). A tendency towards a reduced neutrophil migration after 8-Br-cGMP infusion was shown; however, the changes in comparison to the control animals were not statistically significant (Group I, 1.0+/-0.2 deltaOD/mg/min vs Group II, 1.7+/-0.3 deltaOD/mg/min; P = 0.13). Pulmonary- and systemic hemodynamics, and allograft gas exchange did not differ between groups. CONCLUSIONS: The results indicate that substitution of the NO pathway by administration of the second messenger cGMP at the time of reperfusion improves post-transplant lung allograft function.     

Systemic perfluorocarbons suppress the acute lung inflammation after gastric acid aspiration in rats

Perflurocarbons (PFCs) are used during liquid ventilation and as hemoglobin substitutes. PFCs reduce free radical generation and damage to the lung during liquid ventilation. Thus, we examined the effects of parenteral administration of PFCs on lung injury after acid aspiration. Rats were treated with intraperitoneal injection of either FC-77 or IV injection of Fluosol. Controls received intraperitoneal or IV normal saline (NS) before or at the time of injury and then were injured by instillation of NS + HCl (pH = 1.25) into their lungs via a tracheotomy. The animals were exposed to air or 98% oxygen, breathing spontaneously. The rats were injected with 0.05 microCi of (125)I-albumin (bovine serum albumin) before injury. The extent of lung injury was assessed 5 h postinjury by compliance and lung albumin permeability index measurement. Myeloperoxidase (MPO) activity and histologic examination were used to assess neutrophilic infiltration. Both FC-77 and Fluosol decreased the permeability index compared with controls (1.05 +/- 0.08; 1.08 +/- 0. 12, respectively, versus 1.34 +/- 0.21) and improved lung compliance after intratracheal instillation of 1.2 mL/kg of HCl/NS, pH = 1.25 + hyperoxia injury (P < 0.05). Lung MPO activity decreased in the FC-77 group and was associated with a concomitant decrease in neutrophil infiltration. MPO activity of the spleen increased after FC-77 treatment. The administration of FC-77 decreased the severity of lung permeability changes associated with acid in the presence or absence of hyperoxia exposure. These data suggest that attenuation of neutrophilic infiltration by PFCs decreases lung injury. IMPLICATIONS: Intraperitoneally administered perfluorocarbons in rats attenuate the neutrophilic infiltration in the lung after acid aspiration, thereby decreasing the alveolar protein leakage and improving pulmonary compliance.     

一氧化碳释放分子对重症急性胰腺炎肺损伤保护作用的实验研究

目的 探讨一氧化碳释放分子(CORM-2)对大鼠重症急性胰腺炎(SAP)肺损伤的保护作用及机制.方法 30只雄性Wistar大鼠随机分为3组(n=10):sham组、SAP组,CORM-2组.以3.5%牛磺胆酸钠逆行注射胰胆管的方法制作SAP模型.CORM-2组于SAP造模0.5 h后经阴茎背动脉注射CORM-2(8 mg/kg).各组均于造模6 h后取材,测定血清肿瘤坏死因子-α(TNF-α)含量;采用RT-PCR法检测肺组织细胞因子诱导的中性粒细胞趋化因子(CINC)及细胞间黏附分子-1(ICAM-1)mRNA的表达;同时检测肺组织髓过氧化物酶(MPO)活性、湿/干重比及对肺脏进行病理学评分.结果 与SAP组相比,CORM-2组血清TNF-α水平、肺组织病理损伤程度、湿/干重比、MPO活性、CINC及ICAM-1 mRNA的表达均显著降低(P＜0.05).结论 应用CORM-2能够降低血清TNF-α水平、下调肺组织CINC及ICAM-1 mRNA的表达,进而有效地抑制肺组织中性粒细胞的大量浸润,从而对SAP肺损伤起到明显的保护作用.     

Antibody against neutrophil adhesion improves reperfusion and limits alveolar infiltrate following unilateral pulmonary artery occlusion.

Relief of unilateral pulmonary arterial occlusion results in bilateral lung injury and results in only partial restoration of pulmonary blood flow distal to the site of occlusion. We hypothesized that the "no reflow" phenomenon was in part due to neutrophil adherence and aggregation in the pulmonary vasculature. The study was carried out in two phases. First, we studied the effect of neutrophil depletion on left lung blood flow following 24 hr of left pulmonary artery occlusion. Hydroxyurea was used to deplete circulating neutrophils to 77 +/- 18/mm3 (means +/- sem) (n = 6) as compared to 708 +/- 165/mm3 in control rabbits (n = 8). In both groups left lung blood flow immediately following reperfusion was markedly reduced at 6.4 +/- 2.2% of cardiac output in control rabbits and 7.3 +/- 2.3 in treated rabbits. However, at 4 hr, neutrophil-depleted animals had significantly greater flow (18.7 +/- 3.6 vs 8.4 +/- 2.3% for control rabbits, P less than 0.05). In both groups, flow remained substantially below the normal rabbit left lung blood flow of 39.8 +/- 2.2%. To test whether the improved reflow was due to decreased numbers of neutrophils limiting aggregation, or whether active neutrophil adherence played a role, we tested the effect of a monoclonal antibody that interferes with neutrophil adhesiveness (MoAb 60.3) on reflow and on neutrophil emigration into the alveoli. We found that MoAb 60.3 did not affect initial reflow.(ABSTRACT TRUNCATED AT 250 WORDS)