Pre-treatment of donor with 1-deamino-8-d-arginine vasopressin could alleviate early failure of porcine xenograft in a cobra venom factor treated canine recipient.

OBJECTIVE: Unlike cardiac or renal xenotransplants, the depletion of complement using cobra venom factor (CVF) does not improve pulmonary xenograft survival. Several cases suggest that the swine von Willebrand factor (vWF) may play a major role in presenting a different pathogenesis of pulmonary xenograft dysfunction from other organs. To evaluate the role of vWF and the complement system in mediating hyperacute vascular injury of pulmonary xenografts and elucidate pathogenesis of the injury, we performed swine-to-canine orthotropic single lung xenotransplantation after pre-treatment of 1-deamino-8-d-arginine vasopressin (DDAVP) and CVF. METHODS: We set up three groups for lung xenotransplantation: group I served as the control group; group II, recipients pre-treated with CVF; group III, donors pre-treated with DDAVP (9 mg/kg, 3 days)/recipients pre-treated with CVF (60 u/kg). Hemodynamic data, coagulation and complement system parameters, and grafted lung pathologies were examined serially for 3h after transplantation. RESULTS: DDAVP infusion reduced the vWF content in swine lung tissue in vivo (7.7+/-2.4 AU/mg vs 16.0+/-5.6 AU/mg, P < 0.0001). Infusion of CVF 24 h prior to transplantation effectively depleted the recipient's serum C3 and complement hemolytic activity below the detectable range. Regardless of the use of CVF, both groups I and II transplanted with unmodified grafts showed an immediate drop in leukocytes and platelet counts after transplantation. However, in group III, in recipients transplanted with DDAVP pre-treated swine lung, the platelet count did not decrease after transplantation (P = 0.0295). The decrease of plasma antithrombin and fibrinogen tended to be attenuated in group III. Light microscopic examination revealed extensive vascular thromboses in both capillary and larger vessels, as well as early pulmonary parenchymal damage in groups I and II, but were rarely observed in group III. CONCLUSIONS: Complement inhibition alone was not enough to alleviate intravascular thrombosis, the main pathology in pulmonary xenotransplantation. Pre-infusion of DDAVP to the donor animal was effective in preventing platelet sequestration and attenuated intravascular thrombosis. It is suggested that the strategies targeting vWF would be promising for successful pulmonary xenotransplantation.     

Prolonged Function of Macrophage, von Willebrand Factor-Deficient Porcine Pulmonary Xenografts

Porcine von Willebrand factor (vWF) activates human and primate platelets. Having determined the importance of pulmonary intravascular macrophages (PIMs) in pulmonary xenotransplantation, we evaluated whether, in the absence of PIMs, vWF might play a role in pulmonary xenograft dysfunction. Utilizing a left single-lung transplant model, baboons depleted of anti-alphaGal antibodies received lungs from either vWF-deficient (n = 2); MCP-expressing (n = 5); MCP PIM-depleted (n = 5); or vWF-deficient PIM-depleted swine (n = 3). Two out of three of the PIM-depleted, pvWF deficient grafts survived longer than any previously reported pulmonary xenografts, including PIM-depleted xenografts expressing human complement regulatory proteins. Depletion of PIM's from vWF-deficient lungs, like depletion of PIM's from hMCP lungs, resulted in abrogation of the coagulopathy associated with pulmonary xenotransplantation. Thus, in terms of pulmonary graft survival, control of adverse reactions involving pvWF appears to be equally or even more important than is complement regulation using hMCP expression. However, based on the rapid failure of PIM-sufficient, pvWF-deficient pulmonary xenografts, pVWF-deficient pulmonary xenografts appear to be particularly sensitive to macrophage-mediated damage. These data provide initial evidence that vWF plays a role in the 'delayed' (24 h) dysfunction observed in pulmonary xenotransplantation using PIM depleted hMCP organs.     

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.     

杀菌性/通透性增加蛋白模拟肽对内毒素/脂多糖致小鼠急性肺损伤的保护作用

目的　观察杀菌性/通透性增加蛋白模拟肽(BNEP)对内毒素/脂多糖(LPS)致小鼠急性肺损伤(ALI)的作用。　方法　将BALB/c小鼠随机分为对照组、LPS组、BNEP组,每组20只。LPS组和BNEP组分别经鼻滴注等渗盐水(NS) LPS和NS LPS 尾静脉注射BNEP复制小鼠ALI模型。对照组处理方式类似,但仅滴注NS.检测各组小鼠肺脏湿干重比、肺血管通透性、肺组织病理学变化,应用免疫组织化学法检测肺组织中Toll样受体(TLR) 2、4表达水平的变化。　结果　BNEP组与LPS组比较,肺湿干重比减小,肺血管通透性降低,肺内以中性粒细胞为主的炎性细胞浸润减轻, TLR2、4在肺组织中的表达减弱(两组TLR2分别为128±10、214±12,P<0. 01).　结论　BNEP对由LPS引起的小鼠ALI有较好的保护作用。     

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 (i.e., 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 (CVVH), 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 CVVH (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 CVVH 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 (arterial oxygen tension, 268 +/- 33 vs. 176 +/- 67 mmHg, respectively, P < 0.01). In addition, treatment with CVVH attenuated the endotoxin-induced increase in peak inspiratory pressure and increased lung compliance.     

瑞芬太尼对兔内毒素性急性肺损伤的影响

目的 探讨瑞芬太尼对兔内毒素性急性肺损伤(Au)的影响.方法 健康成年雄性新西兰大白兔30只,体重2.5～3.5 kg,随机分为5组(n=6):对照组(C组)、ALI组、低剂量瑞芬太尼组(LR组)、中剂量瑞芬太尼组(MR组)和高剂量瑞芬太尼组(HR组).C组经30 min静脉输注生理盐水10 ml;ALI组经30 min静脉输注大肠杆菌内毒索(LPS)0.5 mG/kg;LR组、MR组和HR组分别静脉输注瑞芬太尼0.2、0.4和0.8μg·kg~(-1)·min~(-1)至处死,输注15 min时开始给予LPS,方法同ALI组.于LPS输注前即刻(T_0)、输注结束后1、2.5、5.5 h时记录平均动脉血压(MAP)、心率(HR)和气道峰压(P_(peak),测定动脉血氧分压(PaO_2)和血浆细胞间粘附分子1(ICAM-1)浓度,称量肺组织湿重(W)和干重(D),计算W/D比,并在光镜和电镜下观察肺组织病理学结果.结果 与C组比较,ALI组MAP、HR和PaO_2,降低,W/D比、P_(peak)和血浆ICAM-1浓度升高(P<0.05);与ALI组比较,LR组、MR组和HR组MAP、HR 升高,肺组织W/D比降低,P(peak)和血浆ICAM-1浓度降低,PaO_2升高(P<0.05);与LR组比较,MR组和HR组MAP、HR、P(peak)、血浆ICAM-1浓度和肺组织W/D比降低,PaO_2升高(P<0.05);与MR组比较,HR组注肺组织W/D比降低,PaO_2升高(P<0.05).LR组、MR组和HR组肺组织病理学损伤较ALI组减轻.结论 瑞芬太尼可减轻兔内毒素性急性肺损伤,且呈剂量依赖性,其机制可能与抑制ICAM-1的表达有关.     

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.     

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.     

Attenuation of acute lung injury with propofol in endotoxemia

Endotoxin causes acute lung injury (ALI) through many mediators of inflammatory and immune responses. Propofol is an antiinflammatory and immunosuppressive drug. We conducted this study to evaluate whether propofol attenuates ALI associated with endotoxemia. Thirty-two anesthetized rabbits were randomly divided into four groups (n = 8 each). ALI was induced by IV endotoxin 5 mg/kg over 30 min in 3 groups. In 2 of the ALI groups, IV administration of propofol (2 or 5 mg/kg as a bolus followed by continuous infusion at 4 or 15 mg x kg(-1) x h(-1)) was started 15 min before endotoxin. The other ALI group received soybean-oil emulsion. The nonlung injury control group received infusion of both vehicles. The lungs were mechanically ventilated with 40% oxygen for 6 h after endotoxin. Hemodynamics did not differ among groups. The large dose of propofol attenuated lung leukosequestration, pulmonary edema (as assessed by lung wet/dry weight ratio), and pulmonary hyperpermeability (as assessed by albumin levels in bronchoalveolar lavage fluid) and resulted in better oxygenation, lung mechanics, and histological change. The small dose of propofol failed to do so. Our findings suggest that a large dose of propofol successfully mitigates physiological, biochemical, and histological deterioration in ALI in endotoxemia.     

Anti-CD18 antibody attenuates neutropenia and alveolar capillary-membrane injury during gram-negative sepsis.

Activated polymorphonuclear leukocytes (PMNs) are implicated in the pathogenesis of acute lung injury (ALI) associated with sepsis. Adhesion of activated PMNs to endothelial monolayers is mediated by the CD18 adhesion-receptor complex on the PMN cell surface. Monoclonal antibody 60.3 (MoAb 60.3) blocks CD18-dependent PMN-endothelial adhesion in vitro and in vivo. This study was designed to determine the role of CD18-dependent PMN adhesion in ALI associated with gram-negative sepsis. Anesthetized, ventilated (FiO2 0.5, positive end-expiratory pressure 5 cm H2O) pigs received sterile saline (control, n = 8) or live Pseudomonas aeruginosa, 5 x 10(8) colony-forming units/ml at 0.3 ml/20 kg/min (septic, n = 9) for 1 hour. A third group (n = 7) received MoAb 60.3, 2 mg/kg intravenously, 15 minutes before Pseudomonas infusion. Animals were studied for 300 minutes. MoAb 60.3 significantly (p less than 0.05) attenuated the neutropenia seen in sepsis (15 +/- 1 vs 6 +/- 1 x 10(3) PMNs/mm3 at 300 min). Alveolar-capillary membrane injury was assessed by bronchoalveolar-lavage protein content and extravascular lung water determination. MoAb 60.3 significantly (p less than 0.05) reduced BAL protein at 300 minutes (388 +/- 75 vs 1059 +/- 216 micrograms/ml in septic animals) and attenuated the increase in extravascular lung water to 240 minutes (7.1 +/- 2 vs 14.2 +/- 1.2 ml/kg in septic animals). Systemic hypotension, decreased cardiac index, pulmonary hypertension, and relative hypoxemia, all characteristic of this model, were not altered by MoAb 60.3. These data suggest that, in this model of septic ALI, neutropenia is, in part, CD18 dependent and that blocking CD18-dependent PMN adhesion protects the alveolar-capillary membrane independently of altered hemodynamic status.     

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.     

Ibuprofen prevents deterioration in static transpulmonary compliance and transalveolar protein flux in septic porcine acute lung injury

The effects of intravenous ibuprofen on measurements of pulmonary function and alveolar capillary membrane permeability to protein in sepsis-induced porcine acute lung injury (ALI) were studied. Young swine (15-25 kg) were anesthetized, cannulated, and ventilated (5 cm H2O PEEP, 0.5 FIO2, and 15 cc/kg tidal volume). Three groups were studied: septic animals (Ps, n = 10) received Pseudomonas aeruginosa for 1 hr IV, controls (C, n = 9) received 0.9% NaCl, and ibuprofen-treated septic animals (Ps + Ibu, n = 7) received ibuprofen 12.5 mg/kg at 0 and 120 min post Ps. Systemic (SAP) and pulmonary (PAP) arterial pressures, PaO2, cardiac index (CI), static lung compliance (CL), EVLW (thermal cardiogreen), and peripheral white blood cell counts (WBC) were measured. Bronchoalveolar lavage (BAL) was performed for protein and % neutrophil (%PMN) content. Results: Ps produced significant (p less than 0.05) decreases in CL, PaO2, SAP, CI, and peripheral WBC and increases in PAP, EVLW, BAL protein, and %PMN's vs. controls. Ibu prevented the early increase in PAP and attenuated the late increase in PAP and EVLW. Ibu also maintained PaO2, CL, BAL protein, and %PMN's in BAL at control levels, but exhibited no significant effect on peripheral leukopenia. These data strongly suggest that ibuprofen administered before and at 120 min after onset of Pseudomonas infusion improves lung compliance and affects neutrophil function sufficiently to significantly ameliorate many of the physiologic derangements in acute sepsis.     

Pulmonary net release of tissue-type plasminogen activator during porcine primary and secondary acute lung injury

BACKGROUND: Tissue-type plasminogen activator (tPA) is a key mediator of fibrinolysis. Matching of pulmonary perfusion and ventilation is a critical denominator of oxygenation in acute lung injury (ALI). This study investigates pulmonary venoarterial plasma tPA gradients in association with acute ALI induced by bronchoalveolar lavage (BAL) and endotoxinemia (ETX). METHODS: Twenty-one anaesthetized, ventilated pigs were allocated to control (CTRL, n=5), bronchoalveolar saline lavage (BAL, n=8) or infusion of Escherichia coli endotoxin (ETX, n=8). Total tPA was analyzed in plasma (ELISA calibrated for porcine tPA). The inflammatory response was assessed by TNFa levels (ELISA). All variables were assessed at baseline and 2 h following ALI. RESULTS: Bronchoalveolar lavage and ETX induced similar increases in pulmonary shunt whereas pulmonary vascular resistance was significantly more increased in ETX animals. Cardiac output remained stable in BAL animals but decreased in ETX animals. The pulmonary venoarterial tPA plasma gradient increased in ETX animals, yielding a positive pulmonary net flux of tPA, which was absent in BAL animals. TNFalpha levels increased in ETX, but not in BAL, animals. A significant correlation was observed between TNFalpha and tPA plasma levels in ETX animals. All variables remained unchanged in CTRL animals. CONCLUSION: Plasma changes of tPA levels support a pulmonary release of tPA in early experimental ALI induced by acute ETX but not lavage, and are related to the inflammatory response. Despite increased vascular fibrinolytic capacity in ETX animals, pulmonary dysfunction was not different from BAL animals. The results demonstrate the close relation between inflammation and coagulation in early ALI.     

The role of antibodies in dysfunction of pig-to-baboon pulmonary transplants

OBJECTIVE: Pulmonary transplantation has become the preferred treatment for end-stage lung disease, but application of the procedure is limited because of a paucity of donors. One way to solve donor limitations is to use animal organs as a donor source or xenotransplantation. The current barrier to pulmonary xenotransplantation is the rapid failure of the pulmonary xenograft. Although antibodies are known to play a role in heart and kidney xenograft rejection, their involvement in lung dysfunction is less defined. This project was designed to define the role of antibodies in pulmonary graft rejection in a pig-to-baboon model. METHODS: Orthotopic transgenic swine left lung transplants were performed in baboons depleted of antibodies by one of three techniques before transplantation: (1) ex vivo swine kidney perfusion, (2) total immunoglobulin-depleting column perfusion, and (3) ex vivo swine lung perfusion. Results were compared with those of transgenic swine lung transplants in unmodified baboons. RESULTS: All three techniques of antibody removal resulted in depletion of xenoreactive antibodies. Only pretransplantation lung perfusion improved pulmonary xenograft function compared with lung transplantation in unmodified baboons. CONCLUSIONS: The pathogenesis of pulmonary injury in a swine-to-primate transplant model is different from that in renal and cardiac xenografts. Depletion of antibodies alone does not have a beneficial effect and may actually be detrimental.     

阿米洛利预先给药对大鼠内毒素性急性肺损伤的影响

目的 探讨阿米洛利预先给药对大鼠内毒素性急性肺损伤的影响.方法 清洁级雄性SD大鼠32只,体重200～250 g,随机分为4组(n=8):对照组(C组)、急性肺损伤组(ALI组)、阿米洛利组(A组)和阿米洛利预先给药组(AL组).C组股静脉输注生理盐水3 ml,ALI组股静脉输注生理盐水1 ml、内毒素6 mg/kg,A组股静脉输注阿米洛利10 mg/kg、生理盐水2 ml,AL组股静脉输注阿米洛利10 mg/kg、内毒素6 mg/kg,输注速率均为0.05 ml/rain,给药间隔均为30 min.于输注内毒素结束后6 h时处死大鼠取肺,观察肺组织病理学,并行病理学评分,称重后计算肺湿干重比,检测髓过氧化物酶(MPO)活性,测定支气管肺泡灌洗液总蛋白、TNF-α和巨噬细胞炎性蛋白-2(MIP-2)的浓度,采用Western blot法检测肺组织钠氢交换体1(NHE1)、p38丝裂原活化蛋白激酶(p38MAPK)和细胞外信号调节激酶(ERK)的表达水平.结果 与C组比较,ALI组和AL组肺组织病理学评分、肺湿干重比、MPO活性、支气管肺泡灌洗液总蛋白、TNF-α和MIP-2浓度、肺组织NHE1、p38MAPK和ERK的表达水平明显升高(P＜0.01),A组上述指标差异无统计学意义(P＞0.05);与ALI组比较,AL组肺组织病理学评分、肺湿干重比、MPO活性、支气管肺泡灌洗液总蛋白、TNF-α和MIP-2浓度、肺组织NHE1和ERK的表达水平明显降低(P＜0.01),p38MAPK表达差异无统计学意义(P＞0.05).结论 阿米洛利预先给药可减轻大鼠内毒素性急性肺损伤,其机制可能与抑制ERK信号转导通路激活有关.     

Combining partial liquid ventilation and prone position in experimental acute lung injury.

BACKGROUND: Partial liquid ventilation (PLV) and prone position can improve arterial oxygen tension (PaO2) in acute lung injury (ALI). The authors evaluated additive effects of these techniques in a saline lung lavage model of ALI. METHODS: ALI was induced in 20 medium-sized pigs (29.2+/-2.5 kg body weight). Gas exchange and hemodynamic parameters were determined in both supine and prone position in all animals. Thereafter, one group was assigned to PLV with two sequential doses of 15 ml/kg of perfluorocarbon (n = 10); the second group was assigned to gaseous ventilation (n = 10). Gas-exchange and hemodynamic parameters were determined at corresponding time points in both groups in prone and supine position. RESULTS: In the PLV group, positioning the animals prone resulted in an increase of PaO2 prior to PLV and during PLV with both doses of perfluorocarbon when compared to ALI. PLV in supine position was only effective if 30 ml/kg of perfluorocarbon was applied. In the gaseous ventilation group, PaO2 increased reproducibly compared with ALI when the animals were turned prone. A significant additive improvement of arterial oxygenation was observed during combined therapy with 30 ml/kg of perfluorocarbon and prone position in the PLV group compared with either therapy alone. CONCLUSIONS: The authors conclude that combining PLV with prone position exerts additive effects on pulmonary gas exchange in a saline lung lavage model of ALI in medium-sized pigs.     

急性肺损伤大鼠肺组织白介素13mRNA的表达

目的　观察脂多糖 (LPS)介导的急性肺损伤 (ALI)大鼠肺组织白介素 13(IL 13)mRNA表达的变化 ,探讨ALI发生、发展过程中抗炎机制变化的意义。　方法　 (1)由鼠尾静脉注射梯度剂量LPS ,制作ALI模型 (APDS)。 (2 )逆转录PCR法检测肺组织IL 13mRNA含量。　结果　 (1)梯度剂量LPS可以引发不同程度的ALI,当LPS≥ 6mg/kg时 ,大鼠出现急性呼吸窘迫综合征 (ARDS)。 (2 )LPS可以导致肺组织IL 13mRNA表达升高 ,当LPS≥ 6mg/kg时 ,IL 13mRNA表达增加显著。　结论　 (1)尾静脉注射LPS可以复制大鼠ALI模型。 (2 )LPS≥ 6mg/kg是大鼠发生ARDS的临界剂量。 (3)LPS诱导大鼠肺组织IL 13mRNA表达增强 ,与ARDS发生有关     

ONO-1714, a nitric oxide synthase inhibitor, attenuates endotoxin-induced acute lung injury in rabbits

Overproduction of nitric oxide by inducible nitric oxide synthase (iNOS) expressed in the lung is thought to play a crucial role in the pathogenesis of endotoxin-induced acute lung injury (ALI). In this two-part study, we determined whether ONO-1714, a new selective iNOS inhibitor, attenuates endotoxin-induced ALI in rabbits. For Part I of the study, a control group received IV saline and ALI was induced by IV infusion of endotoxin 5 mg/kg over 30 min in 4 groups. Three groups received either 0.1, 0.03, or 0.01 mg/kg of ONO-1714 10 min before the start of endotoxin and the fourth group received saline. For Part II of the study, ALI was induced by endotoxin infusion in all 6 groups. One group was treated with saline. The other 5 groups received ONO-1714 0.1 mg/kg at various timings (10 min before or 1, 2, 3, or 4 h after ALI induction). The lungs were mechanically ventilated with 40% oxygen for 6 h after induction of ALI. In Part I, pretreatment with 0.1 mg/kg ONO-1714 mitigated endotoxin-induced ALI. In Part II, early posttreatment (within 2 h after the insult) with ONO-1714 was as effective as pretreatment in improving oxygenation, lung mechanics, lung leukosequestration, pulmonary edema, and histological change. However, lung damage was not improved in rabbits receiving the drug 3 or 4 h after endotoxin. These data suggest that the current study is a basis for future clinical trials to elucidate whether ONO-1714 can be a promising therapeutic approach in patients with acute respiratory distress syndrome induced by endotoxin/sepsis. IMPLICATIONS: An excess of nitric oxide is thought to play a crucial role in the pathogenesis of acute organ injury in endotoxemia. Early posttreatment with ONO-1714, a nitric oxide synthase inhibitor, attenuated physiological, biochemical, and pathological changes in endotoxin-induced acute lung injury in rabbits.     

Non-anti-Gal alpha1-3Gal antibody mechanisms are sufficient to cause hyperacute lung dysfunction in pulmonary xenotransplantation

BACKGROUND: Hyperacute lung dysfunction, which is always associated with pulmonary pig-to-primate xenotransplantation is not well understood. The mechanisms associated with its occurrence seem to differ from mechanisms involved in hyperacute xenograft rejection seen in porcine hearts or kidneys transplanted into primates. To determine the contribution of anti-Gal alpha1-3Gal antibodies (alphaGAb) in such a process, we performed a set of orthotopic pig lung transplants into baboons depleted of alphaGAb and compared graft function and survival with those receiving only immunosuppression. STUDY DESIGN: Pigs expressing human membrane cofactor protein served as donors. All baboons received triple immunosuppressive therapy. Depletion of alphaGAb in the experimental group (n = 4) was done by way of immunoadsorption using immunoaffinity membranes. Controls (n = 4) did not undergo immunoadsorption. Orthotopic lung transplants were performed through a left thoracotomy. Main pulmonary artery blood flow and pressure, left pulmonary artery blood flow, and left atrial pressure were recorded. RESULTS: At 1 hour after reperfusion, pulmonary artery graft flows and pulmonary vascular resistances (PVR) were better in animals depleted of alphaGAb than in controls (605 +/- 325.2 mL/min versus 230 +/- 21 mL/min; 27.1 +/- 41.3 mmHg/L/min versus 63 +/- 1 mmHg/L/min). But at 3 hours after reperfusion average graft flows in baboons depleted of alphaGAb had decreased to 277.6 +/- 302.2 mL/min and PVRs had increased 58.3 +/- 42.0 mmHg/L/min. On the other hand, controls maintained stable flows and PVRs (223 +/- 23 mL/min; 61 +/- 3 mmHg/L/min). Survival was ultimately better in control baboons when compared with alphaGAb depleted ones (12.2 +/- 3.3 h versus 4.4 +/- 3.2 h). CONCLUSION: Unlike heart and kidney xenograft transplants, hyperacute lung xenograft dysfunction seems to be mediated by factors other than alphaGAb.     

Selectin blockade worsened lipopolysaccharide-induced lung injury in a swine model.

BACKGROUND: Polymorphonuclear leukocytes have been reported to play an important role in various acute lung injuries. Neutrophil recruitment into tissues is a multistep process involving sequential engagement of adhesion molecules. The objective of this study was to determine the effect of selectin inactivation with Sulfo Lewis C (SO3-3betaGal1-3betaGlcNAc-O(CH2)8-COOMe) on the pulmonary response to lipopolysaccharide (LPS) infusion. METHODS: All animals (n = 11) were pretreated with an intramuscular injection of a priming dose of Escherichia coli LPS (10 microg/kg). Eighteen hours later, animals received an intravenous infusion of LPS (20 microg/kg) over 20 minutes. All animals were resuscitated with a lactated Ringer's solution. Group I (G1; n = 5) received no additional treatment. Group II (G2; n = 6) received a bolus injection of Sulfo Lewis C (10 mg/kg) 10 minutes before LPS insult followed by a continuous infusion (1 mg/kg per hour) for the rest of the study. Animals were observed for 5 hours from initiation of the LPS infusion and killed. Cardiopulmonary variables and blood gases were measured serially. The multiple inert gas elimination technique (MIGET) was used to evaluate the matching of air flow and blood flow in the lung 5 hours after LPS infusion. Histologic evaluation of the parenchymal injury was performed by using light microscopy. The number of polymorphonuclear leukocytes and red blood cells in the alveolar spaces per field at 400x magnification were counted in 10 randomly selected fields. RESULTS: Hypoxemia, indexed as Pao2/FIO2, was exacerbated by the administration of Sulfo Lewis C (G1:437+/-33 vs. G2: 241+/-63 mm Hg at 5 hours, p<0.03). This finding is supported by the multiple inert gas elimination technique analysis, which demonstrated significantly greater blood flow to true shunt in G2 (G1:4.42+/-1.75 vs. G2:23.2+/-5.69, p<0.02). There was no difference between the two groups in red blood cell counts in the alveolar spaces. However, polymorphonuclear leukocyte counts were significantly greater in G2 (G1:1.8+/-0.58 vs. G2:9.9+/-2.34, p<0.01). CONCLUSION: Selectin blockade significantly worsened lung injury induced by LPS infusion, and greater numbers of neutrophils were observed in alveolar spaces in the group treated with Sulfo Lewis C. These findings are supported by the multiple inert gas elimination technique analysis, which demonstrated significantly greater blood flow to the true shunt compartment in treated animals. Further studies are required to determine the role of selectins in sepsis-induced lung injury.