Early tumor necrosis factor-alpha release from the pulmonary macrophage in lung ischemia-reperfusion injury

OBJECTIVE: Tumor necrosis factor-alpha is a proinflammatory mediator required for the development of experimental lung ischemia-reperfusion injury. The alveolar macrophage is a rich source of tumor necrosis factor-alpha in multiple models of acute lung injury. The present study was undertaken to determine whether the alveolar macrophage is an important source of tumor necrosis factor-alpha in lung ischemia-reperfusion injury and whether suppression of its function protects against injury. METHODS: Left lungs of Long-Evans rats underwent normothermic ischemia for 90 minutes and reperfusion for up to 4 hours. Treated animals received gadolinium chloride, a rare earth metal that inhibits macrophage function. Injury was quantitated via lung tissue neutrophil accumulation (myeloperoxidase content), lung vascular permeability, and bronchoalveolar lavage fluid leukocyte, cytokine, and chemokine content. Separate samples were generated for immunohistochemistry. RESULTS: Tumor necrosis factor-alpha secretion occurred at 15 minutes of reperfusion and was localized to the alveolar macrophage by immunohistochemistry. In gadolinium-treated animals, lung vascular permeability was reduced by 66% at 15 minutes (P <.03) of reperfusion and by 34% at 4 hours (P <.02) of reperfusion. Suppression of macrophage function resulted in a 35% reduction in lung myeloperoxidase content (P <.03) and similar reductions in bronchoalveolar lavage leukocyte accumulation. Tumor necrosis factor-alpha and microphage inflammatory protein-1alpha protein levels were markedly reduced in the bronchoalveolar lavage of gadolinium-treated animals by enzyme-linked immunosorbent assay. CONCLUSIONS: The alveolar macrophage secretes tumor necrosis factor-alpha protein by 15 minutes of reperfusion, which orchestrates the early events that eventually result in lung ischemia-reperfusion injury at 4 hours. Gadolinium pretreatment markedly reduces tumor necrosis factor-alpha elaboration, resulting in significant protection against lung ischemia-reperfusion injury.     

Endotracheal calcineurin inhibition ameliorates injury in an experimental model of lung ischemia-reperfusion

OBJECTIVES: We previously demonstrated that calcineurin inhibitors given intravenously ameliorate experimental lung ischemia-reperfusion injury. This study evaluates whether these effects can be achieved when these agents are delivered endotracheally. METHODS: Left lungs of Long Evans rats were rendered ischemic for 90 minutes and reperfused for up to 4 hours. Treated animals received tacrolimus endotracheally at doses of 0.2, 0.1, or 0.025 mg/kg 60 minutes before ischemia. Injury was quantitated in terms of vascular permeability. Additional animals treated at a dose of 0.1 mg/kg were assessed for lung tissue myeloperoxidase content and bronchoalveolar lavage leukocyte content. Bronchoalveolar lavage fluid was assessed for cytokine and chemokine content by enzyme-linked immunosorbent assay. Tissue samples were processed for nuclear factor-kappaB activation, and blood levels of tacrolimus were measured in treated animals. RESULTS: Left lung vascular permeability was reduced in treated animals in a dose-dependent fashion compared with controls. The protective effects correlated with a 47% (0.50% +/- 0.06% vs 0.27% +/- 0.08%, respectively) reduction in tissue myeloperoxidase content (P <.004) and marked reductions in bronchoalveolar lavage leukocyte accumulation. This protection was also associated with decreased nuclear factor-kappaB activation and diminished expression of proinflammatory mediators. Blood tacrolimus levels in treated animals at 4 hours of reperfusion were undetectable. CONCLUSIONS: Tacrolimus administered endotracheally is protective against lung ischemia-reperfusion injury in our model. This protection is associated with a decrease in nuclear factor-kappaB activation. This route of tacrolimus administration broadens its potential clinical use and decreases concerns about systemic and renal toxicity. It may be a useful therapy in lung donors to protect against lung ischemia-reperfusion injury.     

Novel broad-spectrum chemokine inhibitor protects against lung ischemia-reperfusion injury.

BACKGROUND: Functional roles for chemokines have been demonstrated in several models of ischemia-reperfusion injury. The redundancy inherent to chemokine pathways makes administration of neutralizing antibodies to any single chemokine ineffective in ameliorating injury. This study was undertaken to define the pattern of chemokine expression in lung ischemia-reperfusion injury (LIRI), and to determine whether a broad-spectrum chemokine inhibitor, NR58-3.14.3, could confer significant protection against LIRI. METHODS: Left lungs of rats were rendered ischemic for 90 minutes and then reperfused for 4 hours. Chemokine secretion into the alveolar space was quantified by enzyme-linked immunoassay. Treated animals received NR58-3.14.3 prior to reperfusion. Vascular injury was measured by lung permeability index, neutrophil accumulation in lung parenchyma was determined by myeloperoxidase (MPO) activity, and alveolar leukocyte counts were quantified in bronchoalveolar lavage (BAL) effluent. A ribonuclease protection assay evaluated mRNA expression of various chemokines. RESULTS: Lavage effluent in untreated animals demonstrated significant increases in the secretion of cytokine-induced neutrophil chemoattractant (CINC), tumor necrosis factor-alpha (TNF-alpha), macrophage inflammatory protein-2 (MIP-2), MIP-1alpha and monocyte chemoattractant protein-1 (MCP-1). Animals receiving NR58-3.14.3 demonstrated a 37% (p < 0.001) reduction in vascular injury and a marked reduction in lung MPO activity (p < 0.001) and alveolar cell counts (p = 0.005). Chemokine inhibition decreased mRNA expression of a number of early response cytokines when compared with positive control animals, and caused a significant decrease (p < 0.04) in the secretion of TNF-alpha. CONCLUSIONS: These studies demonstrate that chemokines are expressed after lung ischemia and reperfusion, and that broad-spectrum chemokine inhibition ameliorates reperfusion injury. mRNA expression of early response cytokines was modulated, and the secretion of TNF-alpha was decreased.     

Depletion of alveolar macrophages by clodronate-liposomes aggravates ischemia-reperfusion injury of the lung.

BACKGROUND: Macrophages play an important role in ischemia-reperfusion injury of various organs. Liposome-encapsulated dichloromethylene diphosphonate (clodronate-liposome) depletes local macrophages in vivo. However, the effect of this approach on alveolar macrophages in pulmonary ischemia-reperfusion injury has not yet been evaluated. METHODS: Clodronate-liposomes in Hanks' balanced salt solution (HBSS) or HBSS alone were given intratracheally to anesthetized male Lewis rats in the clodronate or the control group (n = 6/each group). After 3 days, we subjected the lungs to ischemia (37 degrees C, 60 minutes) and reperfusion (60 minutes) in an isolated blood-perfused rat lung model. Analysis during reperfusion included gas exchange, hemodynamics, and airway mechanics. At the end of reperfusion, we determined leukocyte recruitment and macrophage inflammatory protein-2 (MIP-2) in bronchoalveolar lavage fluid. RESULTS: In the clodronate group, 4 experiments had to be terminated within 10 minutes of reperfusion because of severe lung injury, whereas all lungs of the controls could be studied during the 60-minute reperfusion period (p < 0.05). Clodronate significantly decreased dynamic airway compliance (p < 0.05) and increased airway resistance. Besides a tendency toward greater pulmonary vascular resistance, this was associated with recruitment of polymorphonuclear neutrophils (p < 0.05) and increased MIP-2 concentrations in the bronchoalveolar lavage fluid (p < 0.05). CONCLUSIONS: Intratracheal administration of liposome-encapsulated clodronate does not benefit, but aggravates, warm ischemia-reperfusion injury of the lung, increasing MIP-2-associated alveolar neutrophil recruitment and airway mechanical dysfunction.     

Beta-chemokine function in experimental lung ischemia-reperfusion injury

BACKGROUND: Although chemokines are functionally important in models of ischemia-reperfusion injury, little is known about their role in lung ischemia-reperfusion injury (LIRI). This study examined the role of the beta-chemokines, macrophage inflammatory protein (MIP)-1alpha, monocyte chemoattractant protein (MCP)-1, and regulated upon activation normal T cells expressed and secreted (RANTES) in LIRI. METHODS: Left lungs of Long-Evans rats underwent normothermic ischemia for 90 minutes and reperfusion for up to 4 hours. Treated animals received anti-MIP-1alpha, anti-MCP-1, or anti-RANTES antibodies before reperfusion. Changes in lung vascular permeability were measured with iodine 125-labeled bovine serum albumin. Neutrophil accumulation in the lung parenchyma was determined by myeloperoxidase activity, and bronchoalveolar lavage was performed to measure leukocyte cell counts. Western blots, Northern blots, and ribonuclease protection assays assessed beta-chemokine messenger RNA and protein levels. RESULTS: Animals receiving anti-MIP-1alpha demonstrated reduced vascular permeability compared with controls (p < 0.001). Attenuation of permeability was less dramatic in animals treated with anti-MCP-1 and anti-RANTES antibody, which demonstrated permeability decreases of 15% and 16%, respectively (p < 0.02). Lung neutrophil accumulation was reduced in animals receiving anti-MIP-1alpha antibody (p < 0.005) but was unchanged in animals receiving either anti-MCP-1 or anti-RANTES. Bronchoalveolar lavage leukocyte content was also reduced by treatment with anti-MIP-1alpha (p < 0.003) and was unchanged in anti-MCP-1-treated and anti-RANTES-treated animals. MIP-1alpha treatment decreased tumor necrosis factor-alpha messenger RNA in injured left lungs. CONCLUSIONS: MIP-1alpha is functionally significant in the development of LIRI. It likely exerts its effects in part by mediating the expression of proinflammatory and antiinflammatory cytokines and influencing tissue neutrophil recruitment. MCP-1 and RANTES seem to play relatively minor roles in the development of direct LIRI.     

The role of proinflammatory cytokines in lung ischemia-reperfusion injury

OBJECTIVE: Proinflammatory cytokines are known to play roles in ischemia-reperfusion injury of the heart, kidney, small bowel, skin, and liver. Little is known about their roles in ischemia-reperfusion injury of the lung. This study was undertaken to define the role of 2 proinflammatory cytokines, tumor necrosis factor alpha and interleukin 1beta, in ischemia-reperfusion injury of the lung. METHODS: Left lungs of male rats were rendered ischemic for 90 minutes and reperfused for up to 4 hours. Treated animals received anti-tumor necrosis factor alpha or anti-interleukin 1beta antibody before reperfusion. Increased vascular permeability in the lung was measured by using iodine 125-labeled bovine serum albumin. Neutrophil sequestration in the lung parenchyma was determined on the basis of activity. Bronchoalveolar lavage was performed to measure cell counts. Separate tissue samples were processed for histology, cytokine protein, and messenger RNA content by using Western blotting and the ribonuclease protection assay. RESULTS: Animals receiving anti-tumor necrosis factor alpha and anti-interleukin 1beta demonstrated reduced injury compared with that seen in positive control animals (vascular permeability of 48.7% and 29.4% lower, respectively; P <.001). Vascular injury was reduced by 71% when antibodies to tumor necrosis factor alpha and interleukin 1beta were administered together. Lung neutrophil accumulation was markedly reduced among animals receiving anti-tumor necrosis factor alpha and anti-interleukin 1beta (myeloperoxidase content of 30.9% and 38.5% lower, respectively; P <.04) and combination blockade afforded even greater protection (52.4% decrease, P <.01). Bronchoalveolar lavage leukocyte content was also reduced by treatment with anti-tumor necrosis factor alpha, anti-interleukin 1beta, and combination treatment. Reductions in permeability, myeloperoxidase, and bronchoalveolar lavage leukocyte content also resulted in a decrease in a histologic injury. Finally, anti-tumor necrosis factor alpha and anti-interleukin 1beta treatment resulted in decreased messenger RNA expression for a number of early response and regulatory cytokines. CONCLUSION: Tumor necrosis factor alpha and interleukin 1beta help regulate the development of lung ischemia-reperfusion injury. They appear to promote injury by altering expression of proinflammatory and anti-inflammatory cytokines and influencing tissue neutrophil recruitment.     

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.     

肺泡巨噬细胞活化在急性坏死性胰腺炎大鼠肺损伤中的作用

目的　探讨肺泡巨噬细胞活化在急性坏死性胰腺炎 (ANP)肺损伤中的作用。　方法30只成年SD大鼠随机分为正常对照组、ANP后 1、3、6、12h组 ,每组 6只。逆行性胰胆管注射 3%牛磺酸钠建立ANP大鼠模型 ,正常对照组大鼠自胆胰管内逆行注入生理盐水。经支气管肺泡灌洗获取肺泡巨噬细胞 ,检测支气管肺泡灌洗液中蛋白含量、肺组织髓过氧化物酶 (MPO)水平、肺泡巨噬细胞分泌肿瘤坏死因子α(TNFα)及一氧化氮 (NO)水平。以反转录聚合酶链反应 (RT PCR)法测定肺泡巨噬细胞TNFαmRNA、诱导型一氧化氮合酶 (iNOS)mRNA表达情况。行肺、胰腺组织病理学检查并评分。结果　ANP大鼠肺损伤随着病情进展而逐渐加重 ;肺组织MPO及支气管肺泡灌洗液中蛋白含量逐渐升高 ,12h达最高值 ,分别为 (10 78± 0 5 8)U/g和 (2 0 11 0± 10 5 5 ) μg/ml;肺泡巨噬细胞分泌TNFα、NO水平逐渐升高 ,至 6h达到高峰 ,分别为 (16 2 4 2± 149 2 )pg/ml和 (88 8± 6 5 ) μmol/L ,12h又回落。ANP发生后 ,肺泡巨噬细胞TNFαmRNA、iNOSmRNA的表达情况与TNFα、NO的变化趋势相似。ANP大鼠各组指标与正常对照组相比差异均有显著性意义 (P <0 0 5 )。组织学评分结果表明 ,随着胰腺损伤的加重肺损伤也逐渐加重。肺泡巨噬细胞TNFαmRNA、iNOSmRNA     

七氟醚对内毒素致急性肺损伤鼠肺泡毛细血管膜通透性的影响

目的　探讨七氟醚对内毒素致急性肺损伤鼠肺泡毛细血管膜通透性和肺泡灌洗液内炎性细胞的影响。方法　 4 8只Wistar大鼠 ,麻醉后静注伊万斯蓝 5 0mg/kg后 ,随机分为 4组 ,每组 12只。对照组 :股静脉注射生理盐水 1 2ml后机械通气 4h ;内毒素组 :股静脉注射内毒素 5mg/kg后机械通气 4h ;七氟醚 1L组和七氟醚 2L组 :股静脉注射内毒素 5mg/kg后机械通气 ,分别吸入肺泡气最低有效浓度 (MAC)为 1 0和 1 5的七氟醚 4h。 4h后取肺组织测定 :病理形态学积分 ,肺湿 /干重比 ,肺水含量 ,肺通透指数 ,伊万斯蓝含量和肺泡灌洗液内炎性细胞总数及百分比。结果　七氟醚1L组肺通透指数、伊万斯蓝含量、病理形态学积分分别由 4 6 8± 0 82 ,( 112 2 1± 11 4 4 )ng/mg ,9 17± 0 90下降到 3 98± 0 5 0 ,( 92 85± 11 80 )ng/mg ,7 5 0± 0 96 ;七氟醚 2L组下降到 3 91±0 34,( 96 33± 8 79)ng/mg ,7 6 7± 0 75。结论　 1 0和 1 5MAC七氟醚可降低内毒素所致急性肺损伤肺泡毛细血管膜通透性 ,使肺组织病理损伤减轻     

Activation of alveolar macrophages in lung injury associated with experimental acute pancreatitis is mediated by the liver

OBJECTIVE: To evaluate (1) whether alveolar macrophages are activated as a consequence of acute pancreatitis (AP), (2) the implication of inflammatory factors released by these macrophages in the process of neutrophil migration into the lungs observed in lung injury induced by AP, and (3) the role of the liver in the activation of alveolar macrophages. SUMMARY BACKGROUND DATA: Acute lung injury is the extrapancreatic complication most frequently associated with death and complications in severe AP. Neutrophil infiltration into the lungs seems to be related to the release of systemic and local mediators. The liver and alveolar macrophages are sources of mediators that have been suggested to participate in the lung damage associated with AP. METHODS: Pancreatitis was induced in rats by intraductal administration of 5% sodium taurocholate. The inflammatory process in the lung and the activation of alveolar macrophages were investigated in animals with and without portocaval shunting 3 hours after AP induction. Alveolar macrophages were obtained by bronchoalveolar lavage. The generation of nitric oxide, leukotriene B4, tumor necrosis factor-alpha, and MIP-2 by alveolar macrophages and the chemotactic activity of supernatants of cultured macrophages were evaluated. RESULTS: Pancreatitis was associated with increased infiltration of neutrophils into the lungs 3 hours after induction. This effect was prevented by the portocaval shunt. Alveolar macrophages obtained after induction of pancreatitis generated increased levels of nitric oxide, tumor necrosis factor-alpha, and MIP-2, but not leukotriene B4. In addition, supernatants of these macrophages exhibited a chemotactic activity for neutrophils when instilled into the lungs of unmanipulated animals. All these effects were abolished when portocaval shunting was carried out before induction of pancreatitis. CONCLUSION: Lung damage induced by experimental AP is associated with alveolar macrophage activation. The liver mediates the alveolar macrophage activation in this experimental model.     

Elastolytic activity of alveolar macrophages in chronic bronchitis: comparison of current and former smokers

We have compared the macrophage elastolytic activity of a group of current and former smokers with irreversible airflow obstruction. Elastolytic activity was determined in an initial bronchoalveolar lavage cell population and in alveolar macrophages cultured for three days, to investigate whether enhanced macrophage elastolytic activity alone is a determining factor in the susceptibility of some smokers to obstructive lung disease. Twenty current smokers and 12 former smokers who had abstained from smoking for at least three years were studied. All patients had spirometric evidence of irreversible air flow obstruction. Current smokers had a cell yield (mean +/- SD) of 138.7 +/- 36.4 X 10(6) cells (alveolar macrophages 94.2% +/- 2.1%) compared with 31.4 +/- 14.1 X 10(6) cells (macrophages 86.5% +/- 4.7%) in former smokers. Elastolytic activity in the initial lavage cell population from current and former smokers, measured with the synthetic elastase substrate succinyl-L-alanyl-L alanyl-L-alanine-p-nitroanilide, and expressed as the equivalent of 1 microgram of porcine pancreatic elastase, was respectively 0.113 +/- 0.003 and 0.096 +/- 0.004 microgram pancreatic elastase/mg cell protein. After three days in culture macrophage elastolytic activity in the current and former smokers' cells was respectively 0.107 +/- 0.006 and 0.011 +/- 0.001 microgram pancreatic elastase/mg cell protein (p less than 0.05). The elastase activity of the cultured alveolar macrophages from five current smokers had the inhibitor profile of a metalloproteinase. Our results indicate that enhanced macrophage elastolytic activity alone is not a determining factor in the susceptibility of some smokers to develop obstructive lung disease.     

Hypertonic resuscitation of hemorrhagic shock upregulates the anti-inflammatory response by alveolar macrophages

BACKGROUND: Resuscitated hemorrhagic shock predisposes patients to the development of acute respiratory distress syndrome (ARDS). Hypertonic saline (HTS) has been shown to inhibit immune cell activation in response to lipopolysaccharide (LPS) in vitro and to reduce lung damage when used for resuscitation of hemorrhagic shock in vivo. We hypothesize that HTS resuscitation of hemorrhagic shock may exert this anti-inflammatory effect by modulating alveolar macrophage function leading to an altered balance between the proinflammatory and the counter-inflammatory response. METHODS: A 2-hit rat model of shock resuscitation was used. Alveolar macrophages were harvested by bronchoalveolar lavage (BAL), and tumor necrosis factor (TNF)-alpha and interleukin (IL)-10 were quantified in the cell culture supernatants by enzyme-linked immunosorbent assay (ELISA). Alternatively, 1 hour after resuscitation, animals received endotracheal LPS followed by endotracheal anti-IL-10 neutralizing antibody. Lung injury was determined by measuring BAL neutrophil counts 4 hours after LPS in vivo administration. RESULTS: Systemic administration of HTS significantly modulates the responsiveness of alveolar macrophages. Specifically, HTS resuscitation inhibited LPS-induced TNF-alpha production while enhancing IL-10 release in response to LPS administered ex vivo and in vivo. Anti-IL-10 antibody in vivo partially reversed the lung protective effect of HTS resuscitation. CONCLUSIONS: HTS resuscitation exerts an immunomodulatory effect on alveolar macrophages by shifting the balance of pro- and counter-inflammatory cytokine production in favor of an anti-inflammatory response. The in vivo data suggest a causal role for HTS-induced augmented IL-10 as protective. These findings suggest a novel mechanism for the in vivo salutary effect of HTS resuscitation on lung injury after resuscitated hemorrhagic shock.     

Hypertonic saline infusion for pulmonary injury due to ischemia-reperfusion

HYPOTHESIS: Inhibition of neutrophil-endothelial cell interactions by hypertonic saline (HTS) may confer protection against organ injury in states of immunologic disarray. This study tested the hypothesis that infusion of HTS modulates the development of end-organ injury in a model of lower-torso ischemia-reperfusion injury. DESIGN: Ischemia-reperfusion injury was induced in 30 male Sprague-Dawley rats by infrarenal aortic cross-clamp for 30 minutes, followed by reperfusion for 2 hours. At 0 and 60 minutes of reperfusion, intravenous HTS (7.5% sodium chloride, 4 mL/kg) was administered to 6 rats each, and another 12 received either 4 or 30 mL/kg of isotonic sodium chloride solution. Six rats received HTS, 4 mL/kg, before ischemia. At 2 hours, we assessed liver function, pulmonary injury, neutrophil infiltration (myeloperoxidase activity), endothelial permeability (bronchoalveolar lavage and wet-dry weight ratios), and proinflammatory cytokine levels (tumor necrosis factor alpha and interleukin 6). RESULTS: Infusion with HTS before or after ischemia significantly reduced end-organ injury. Histopathologic pulmonary injury scores were markedly attenuated in the HTS group (5.82 +/- 1.3) and the HTS pretreated group (4.91 +/- 1.6) compared with the isotonic sodium chloride solution groups (8.54 +/- 1.1) (P =.04). Pulmonary neutrophil sequestration (2.07 +/- 0.23) and increased endothelial permeability (4.68 +/- 0.44) were manifest in animals resuscitated with isotonic sodium chloride solution compared with HTS treatment (1.54 +/- 0.19 [P =.04] and 2.06 +/- 0.26 [P =.02]) and pretreatment (1.18 +/- 0.12 [P =.04] and 1.25 +/- 0.07 [P =.002]). In addition, a significant reduction in serum tumor necrosis factor alpha (P =.04) and interleukin 6 (P =.048) levels was observed, whereas HTS resuscitation attenuated the upsurge in aspartate transaminase (P =.03) and alanine transaminase levels (P =.047). CONCLUSIONS: Resuscitation with HTS attenuates the pulmonary edema and tissue injury due to lower-torso ischemia-reperfusion and maintains a more benign immunologic profile.     

The role of neutrophils, oxidants, and proteases in the pathogenesis of acid pulmonary injury.

We recently reported a biphasic injury pattern of nonlethal acid aspiration pneumonitis in rats. The first phase consisted of the immediate effects of the direct tissue injury, and the second phase was associated with a neutrophilic inflammatory response. Using this model, the present report examines the possible role of neutrophils, oxidants, and proteases in the pathogenesis of the second phase of this lung injury. Acid aspiration injury was induced by instillation of saline/HCl, pH = 1.25, into the trachea of rats. Lung injury was assessed by measuring the degree of alveolar capillary permeability to 125I-labeled albumin (permeability index [PI]). Rats made neutropenic with polyclonal antineutrophil antibody had a lower PI (0.44 +/- 0.07, P less than 0.05) 6 h after acid aspiration than similarly injured animals with normal whole blood neutrophil counts (PI = 0.85 +/- 0.03). Even though neutrophils appeared necessary for the full development of the lung injury in this model, the administration of different intravenous and/or intratracheal concentrations of either deferoxamine or catalase offered no protection against injury. This suggests that neutrophil oxidants were minimally involved in the injury. Large increases in leukocyte-free serine protease activity (1,477 +/- 438 u/ml, P less than 0.05) were detected in the bronchoalveolar lavage fluid from the saline/HCl, pH = 1.25, injured rats at 6 h postinjury, as compared to saline/HCl, pH = 5.3, treated control animals (2.7 +/- 0.2 u/ml). This study supports the hypothesis that neutrophils are necessary for the full expression of acid-induced lung injury and that the generation of leukocyte-derived oxidants does not appear to be the primary mechanism involved in this injury.(ABSTRACT TRUNCATED AT 250 WORDS)     

Intra-alveolar macrophage numbers in current smokers and non-smokers: a morphometric study of tissue sections.

BACKGROUND: The alveolar macrophage is believed to be important in the defence of the lung and possibly in the pathogenesis of lung disease. Cell counts in bronchoalveolar lavage fluid have suggested that smokers have an increased number of alveolar macrophages but have not enabled the number to be related to a measure of lung structure. METHODS: The number of alveolar macrophages was counted in histological sections from lung resection specimens from a group of smokers and non-smokers. The results were related to a measurement of lung structure obtained by means of an automated morphometric technique and expressed in terms of units of lung volume or of lung surface area. RESULTS: The smokers had a significantly increased number of alveolar macrophages per unit lung volume and per unit surface area, through the relative increase was less than has appeared from bronchoalveolar lavage studies. When smokers and non-smokers with similar lung structure were compared the smokers had more alveolar macrophages, indicating that smoking and not loss of lung structure is responsible for the increase. CONCLUSIONS: Smokers had more alveolar macrophages than non-smokers when the number was expressed quantitatively with respect to the underlying architecture. Changes in cell populations postulated to be important in the pathogenesis of disease within the lung should be related to lung architecture because this may vary considerably between individuals.