Substance P-induced histamine release in tracheally perfused guinea pig lungs

The capacity of substance P (SP) and endogenously released tachykinins to liberate histamine was examined in isolated tracheally perfused guinea pig lungs. Increasing doses of tracheally injected SP were associated with the recovery of increasing amounts of histamine from lung effluent. The mechanism of SP-induced histamine liberation was explored in studies with neurokinin-(NK) receptor agonists and antagonists. Tracheal injection of either the NK1 agonist [Sar9,Met(O2)11]SP or the NK2 agonist [beta-Ala8]-neurokinin A-(4-10) was associated with a significant increase in histamine recovery from lung effluent. In addition, both the NK1 antagonist CP-99994 and the NK2 antagonist SR-48968 significantly inhibited SP-induced histamine release. These findings support the hypothesis that SP can liberate histamine from guinea pigs lungs by a mechanism that depends predominantly on NK1- and NK2-receptor activation. The liberation of endogenous tachykinins by acute tracheal injection of capsaicin was also associated with augmented histamine recovery, which was inhibited by combined NK1- and NK2-receptor blockade. Tracheal injection of SP was associated with an increase in the percentage of airway mast cells exhibiting histological evidence of degranulation. This study demonstrates that exogenous SP, as well as endogenous tachykinins released from capsaicin-sensitive neurons, can liberate histamine, most likely from airway mast cells, by a mechanism that depends predominantly on the activation of NK1 and NK2 receptors.

Induction of NO synthase in rat cardiac microvascular endothelial cells by IL-1 beta and IFN-gamma

There are important phenotypic differences between endothelial cells of large vessels and the microvasculature and among microvascular endothelial cells isolated from different tissues and organs. In contrast to most macrovascular endothelial cells, we demonstrate that cultured cardiac microvascular endothelial cells (CMEC) have no detectable constitutive NO synthase (NOS) activity but have a robust increase in NOS activity in response to specific inflammatory cytokines. To determine the identity of the inducible NOS (iNOS) isoform(s) induced by cytokines, we used reverse-transcription polymerase chain reaction techniques to clone and sequence a 217-bp cDNA fragment from CMEC cultures pretreated with interleukin-1 beta (IL-1 beta) and interferon-gamma (IFN-gamma) that was identical to the corresponding portion of the murine macrophage iNOS cDNA. By use of this CMEC iNOS cDNA as a probe in Northern analyses, IL-1 beta, but not IFN-gamma, increased iNOS mRNA content in CMEC, although IFN-gamma markedly potentiated iNOS induction in these cells. In IL-1 beta- and IFN-gamma-pretreated CMEC, dexamethasone only minimally suppressed the rise in iNOS mRNA, protein abundance, or maximal iNOS enzyme activity in whole cell lysates but suppressed nitrite production by 60% in intact CMEC. Dual labeling of cytokine-pretreated CMEC in primary culture with an anti-iNOS antiserum and a fluorescein-labeled lectin specific for the microvascular endothelium of rat heart (GS-1) confirmed the presence of iNOS expression in these cells. iNOS was also detected in microvascular endothelium in situ in ventricular muscle from lipopolysaccharide-, but not sham-injected, rat hearts.(ABSTRACT TRUNCATED AT 250 WORDS)

Airway neutrophilia and chemokine mRNA expression in sulfur dioxide-induced bronchitis

Airway inflammation in acute and chronic bronchitis includes a prominent neutrophil influx. Using a rat model of sulfur dioxide (SO2)-induced bronchitis, we investigated the role of the polymorphonuclear leukocyte (PMN) chemokines macrophage inflammatory protein-2 (MIP-2) and KC. Adult female rats were exposed to 230 ppm SO2 for 5 h/day for periods of 1 day to 5 wk. Immunohistochemical identification of rat PMNs in trachea cryostat sections allowed quantitation of a marked neutrophil influx into airways of bronchitic rats (PMNs/trachea ring = 55 +/- 26.2 [1 day SO2] versus 3.6 +/- 2.7 [air]; n = 5, P < or = 0.05). Northern analysis of trachea homogenates demonstrated induction of KC and MIP-2 mRNA expression after 1 day of SO2 and persistence of increased expression after longer exposure periods examined. Pretreatment of rats with dexamethasone (0.5 mg/kg) prior to a 1-day acute SO2 exposure prevented induction of chemokine mRNA and abrogated neutrophil influx completely (PMNs/trachea ring = 6.6 +/- 8.8 versus air controls; n = 5, P = 0.96). To determine if chemokine inhibition by dexamethasone could be further studied in vitro, the rat alveolar macrophage cell line NR8383 was treated with dexamethasone (10(-7) M) before stimulation with lipopolysaccharide (10 micrograms/ml). Pretreatment with dexamethasone substantially decreased induction of both MIP-2 and KC mRNA in response to lipopolysaccharide, indicating the potential utility of in vitro systems to identify additional anti-inflammatory agents. These studies support the hypothesis that the chemokines MIP-2 and KC mediate airway neutrophil influx in both acute and chronic SO2-induced bronchitis in the rat.

Functional characterization of rat chemokine macrophage inflammatory protein-2

Expression of mRNA for the C-X-C chemokine, macrophage inflammatory protein-2 (MIP-2), is induced during acute inflammation in rat models of disease. We have characterized the phlogistic potential of rat recombinant MIP-2 (rMIP-2) protein in vitro and in vivo. Recombinant MIP-2 caused marked PMN chemotaxis in vitro, with peak chemotactic activity at 10 nM. Incubation of whole blood with rMIP-2 caused a significant loss of L-selectin and a significant increase in Mac-1 expression on the PMN surface. Under similar conditions rMIP-2 also caused a modest respiratory burst in PMNs. The intratracheal instillation of 10 and 50 micrograms of rMIP-2 caused a significant influx of PMNs into the airspace of the lungs. Rat MIP-2 is a potent neutrophil chemotactic factor capable of causing neutrophil activation and is likely to function in PMN recruitment during acute inflammation in rat disease models.

Reciprocal Rb inactivation and p16INK4 expression in primary lung cancers and cell lines

cdk4-mediated phosphorylation of the retinoblastoma susceptibility protein (Rb) is stimulated by cyclin D1, an oncogene, and inhibited by p16, a candidate tumor suppressor. We examined these proteins in non-small cell lung cancer (NSCLC), which is predominantly Rb positive, and small cell lung cancer (SCLC), which is Rb negative. Most NSCLC and SCLC resection specimens and cell lines overexpress cyclin D1 (indicating that cyclin D1 overexpression and Rb inactivation can coexist in SCLC). However, 9 of 9 Rb-positive NSCLC cell lines have absent or low p16, while an Rb-negative NSCLC line and 5 of 5 SCLC cell lines have high levels of p16. In primary resection specimens, p16 was undetectable in 18 of 27 NSCLC samples and abundant in 4 of 5 SCLC samples. Our data confirm the predicted reciprocity between Rb inactivation and p16 expression in a common human malignancy and define differential p16 expression as a fundamental distinction between NSCLC and SCLC.

Functional characterization of the rat chemokine KC and its importance in neutrophil recruitment in a rat model of pulmonary inflammation

Expression of mRNA for the neutrophil (PMN) chemokine, KC, in rat models of lung injury suggests a role for this chemokine in pulmonary inflammation. We addressed this hypothesis at the protein level by functionally characterizing recombinant rat KC (rKC) in vitro and in vivo. In vitro, rKC induced PMN chemotaxis and increased the expression of CD11b/CD18 on PMNs. Recombinant KC also induced a respiratory burst (quantitated by flow cytometry) in rat PMNs, similar to that caused by its human structural homologue, gro/melanoma growth-stimulating activity, on human PMNs, but less than that caused by IL-8 on human PMNs. Intratracheal instillation of rKC induced dose-dependent PMN influx into airspaces (average PMNs in bronchoalveolar lavage: vehicle = 1.5%, n = 4; rKC (1 microgram) = 11.5%, n = 2; rKC (10 micrograms) = 77.3%, n = 2). A neutralizing anti-KC Ab reduced the chemotactic activity of rat bronchoalveolar lavage fluid collected after the intratracheal administration of LPS (48.3 +/- 8% of control, n = 4). Anti-KC neutralizing Ab markedly inhibited PMN accumulation (71 +/- 6%) within the lungs in response to an intratracheal challenge of LPS. We conclude that rat KC is a major but not exclusive mediator of PMN activation and recruitment during LPS-induced pulmonary inflammation.

Functional characterization of the rat chemokine KC and its importance in neutrophil recruitment in a rat model of pulmonary inflammation

Expression of mRNA for the neutrophil (PMN) chemokine, KC, in rat models of lung injury suggests a role for this chemokine in pulmonary inflammation. We addressed this hypothesis at the protein level by functionally characterizing recombinant rat KC (rKC) in vitro and in vivo. In vitro, rKC induced PMN chemotaxis and increased the expression of CD11b/CD18 on PMNs. Recombinant KC also induced a respiratory burst (quantitated by flow cytometry) in rat PMNs, similar to that caused by its human structural homologue, gro/melanoma growth-stimulating activity, on human PMNs, but less than that caused by IL-8 on human PMNs. Intratracheal instillation of rKC induced dose-dependent PMN influx into airspaces (average PMNs in bronchoalveolar lavage: vehicle = 1.5%, n = 4; rKC (1 microgram) = 11.5%, n = 2; rKC (10 micrograms) = 77.3%, n = 2). A neutralizing anti-KC Ab reduced the chemotactic activity of rat bronchoalveolar lavage fluid collected after the intratracheal administration of LPS (48.3 +/- 8% of control, n = 4). Anti-KC neutralizing Ab markedly inhibited PMN accumulation (71 +/- 6%) within the lungs in response to an intratracheal challenge of LPS. We conclude that rat KC is a major but not exclusive mediator of PMN activation and recruitment during LPS-induced pulmonary inflammation.

Alteration of pulmonary macrophage function by respiratory syncytial virus infection in vitro

Alveolar macrophages (AL) are the first line of defense against inhaled pathogens and are exposed to virus during the course of a respiratory syncytial virus (RSV) infection. Interference of virus with alveolar macrophage functions may contribute to the risk of acquiring secondary bacterial infections during or after respiratory tract infections with RSV or other viral agents. We studied whether murine AL get infected with RSV and whether they support viral replication in vitro. In addition, the effects of RSV on microbicidal and on immunoregulatory functions were examined. Only a subpopulation of AL expressed viral F proteins after exposure of these cells to RSV. Infected AL released only small amounts of infectious virus into the supernatant. The extent of virus replication in AL seemed to be dependent in part on the amount of IFN induced by the virus, as has been demonstrated by infection of lung tissue macrophages and AL in vitro. In general, RSV infection of pulmonary macrophages appeared to be abortive. Nevertheless, release of reactive oxygen intermediates, phagocytosis, and killing of protozoa were reduced in RSV-infected AL in comparison to noninfected AL. In contrast, RSV stimulated secretion of TNF-alpha, IL-1, and IL-6 in an infectious-dose dependent manner. Along with the increased cytokine release, accessory functions of AL were increased after RSV exposure. Thus, exposure of AL to RSV appeared to stimulate their immunoregulatory functions, whereas the microbicidal activity of these cells seemed to be severely diminished.

Alteration of pulmonary macrophage function by respiratory syncytial virus infection in vitro

Alveolar macrophages (AL) are the first line of defense against inhaled pathogens and are exposed to virus during the course of a respiratory syncytial virus (RSV) infection. Interference of virus with alveolar macrophage functions may contribute to the risk of acquiring secondary bacterial infections during or after respiratory tract infections with RSV or other viral agents. We studied whether murine AL get infected with RSV and whether they support viral replication in vitro. In addition, the effects of RSV on microbicidal and on immunoregulatory functions were examined. Only a subpopulation of AL expressed viral F proteins after exposure of these cells to RSV. Infected AL released only small amounts of infectious virus into the supernatant. The extent of virus replication in AL seemed to be dependent in part on the amount of IFN induced by the virus, as has been demonstrated by infection of lung tissue macrophages and AL in vitro. In general, RSV infection of pulmonary macrophages appeared to be abortive. Nevertheless, release of reactive oxygen intermediates, phagocytosis, and killing of protozoa were reduced in RSV-infected AL in comparison to noninfected AL. In contrast, RSV stimulated secretion of TNF-alpha, IL-1, and IL-6 in an infectious-dose dependent manner. Along with the increased cytokine release, accessory functions of AL were increased after RSV exposure. Thus, exposure of AL to RSV appeared to stimulate their immunoregulatory functions, whereas the microbicidal activity of these cells seemed to be severely diminished.

Neutrophil adhesion receptor CD18 mediates remote but not localized acid aspiration injury

BACKGROUND

Acid aspiration leads to lung polymorphonuclear neutrophil (PMN) sequestration and an associated increase in permeability. Although it is known that the neutrophil adhesion receptor (CD18) plays no role in determining PMN accumulations in the region aspirated, we postulated that this PMN adhesion receptor and its endothelial ligand, intercellular adhesion molecule-1 (ICAM-1), mediate remote neutrophil sequestration.

METHODS

Anesthetized rabbits underwent localized aspiration of either 0.1N HCl 0.1 ml/kg (n = 18) or saline solution (n = 18).

RESULTS

After 30 minutes leukopenia was noted, 2290 +/- 200 white blood cells/mm3 (p < 0.05). At 3 hours diapedesis occurred in the aspirated segment with accumulations in bronchoalveolar lavage fluid (X10(4)) of 87 +/- 6 PMN/ml versus control of 6 +/- 1 PMN/ml (p < 0.05). Histologic evidence of generalized lung leukosequestration occurred. The wet to dry weight ratio of the nonaspirated lung rose to 5.7 +/- 0.2 versus control of 3.9 +/- 0.1 (p < 0.05). Treatment (n = 18) with the CD18 monoclonal antibody (mAb) (R15.7, 1 mg/kg) had no effect on neutrophil accumulations in the aspirated segment. However, the mAb attenuated the remote inflammatory response: early leukopenia (5790 +/- 400 white blood cells/mm3); lung leukosequestration (24 +/- 4 PMN/10 high-power fields); protein leak in bronchoalveolar lavage fluid (570 +/- 50 micrograms/ml); and edema, wet to dry weight ratio (4.9 +/- 0.1) (all p < 0.05). Treatment with the ICAM-1 mAb (RR1/1, 1 mg/kg) (n = 9) did not reduce neutrophil accumulations in the aspirated segment but limited the remote inflammatory response.

CONCLUSIONS

Acid aspiration leads to neutrophil adhesion and edema in regions remote from those aspirated via neutrophil CD18 and endothelial ICAM-1.

Nitric oxide in skeletal muscle

Reactive oxygen intermediates modulate skeletal muscle contraction, but little is known about the role of nitric oxide (NO). Here we show that rat skeletal muscle expresses neuronal-type NO synthase and that activity varies among several respiratory and limb muscles. Immunohistochemistry showed prominent staining of type II (fast) fibre cell membranes with antibodies against neuronal-type NO synthase. NO synthase activity in muscles correlated with type II fibre density. Resting diaphragm muscle produced detectable NO chi, but no reactive oxygen intermediates. In contrast, actively contracting muscle generated increased levels of reactive oxygen intermediates. Contractile function was augmented by blockers of NO synthase, extracellular NO chelation, and guanylyl cyclase inhibition; it was depressed by NO donors and by increased levels of cyclic GMP. Force-frequency plots of different muscles showed an inverse correlation between NO synthase activity and force development. Our results support two physiological functions of NO in skeletal muscle. The first is to promote relaxation through the cGMP pathway. The second is to modulate increases in contraction that are dependent on reactive oxygen intermediates and which are thought to occur through reactions with regulatory thiols on the sarcoplasmic reticulum.

Defective pulmonary recruitment of neutrophils in a rat model of endotoxemia

We have characterized a defect in the pulmonary recruitment of neutrophils (PMNs) in rats with experimental endotoxemia. Rats pretreated with intravenous (IV) 0.9% saline (NaCl) showed abundant PMNs in bronchoalveolar lavage (BAL) fluid after intratracheal (IT) lipopolysaccharide (LPS) (5 mg/kg) (54.27 +/- 9.80 x 10(6), n = 7, versus IT saline, 0.73 +/- 0.62 x 10(6), n = 4). In contrast, endotoxemic rats (IV LPS 1.0 mg/kg) failed to show PMN influx after IT LPS (0.40 +/- 0.13 x 10(6) PMNs in BAL fluid, n = 7). Four hours after the IT administration of LPS, the chemotactic activity of BAL fluid from endotoxemic rats (87 +/- 9.92% of maximal chemotaxis toward zymosan-activated serum [ZAS], n = 4) was not significantly different (P > 0.05), from rats pretreated with IV NaCl (61.09 +/- 6.17% of maximal chemotaxis toward ZAS, n = 4). Endotoxemic and control rats showed similar chemotactic gradients in determinations of the BAL/plasma chemotactic activity ratio (BAL/plasma ratio: 2.16 +/- 0.14, n = 4, IV NaCl versus 2.98 +/- 0.14, n = 4, IV LPS, P > 0.05). Serum from untreated rats, rats pretreated with IV NaCl, and endotoxemic rats caused minimal effects on rat PMN chemotaxis in vitro (78.17 +/- 8.16%, 79.29 +/- 7.09%, and 69.28 +/- 9.04% of maximal chemotaxis toward ZAS, respectively, n = 4/group, P > 0.05). Quantitation of PMN adhesion molecules revealed a loss of L-selectin (8 +/- 5% of control group, n = 3), an increase in Mac-1 (776 +/- 82.60% of control group, n = 3), and no change in LFA-1 when normal PMNs were incubated with plasma from rats pretreated with IV LPS (P < 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Inhibition of sphincter of Oddi function by the nitric oxide carrier S-nitroso-N-acetylcysteine in rabbits and humans

Nitric oxide (NO) is an inhibitor of gastrointestinal smooth muscle. Model systems of the gut predict the NO will complex with biological thiol (SH) groups, yielding S-nitrosothiols (RS-NO), which may limit the propensity to form mutagenic nitrosamines. The inhibitory effects of NO and its biologically relevant adducts on sphincter of Oddi (SO) motility have been inferred from animal studies; however, their importance in regulating human SO is not known. The objectives of this study were to (a) provide histologic confirmation of nitric oxide synthase (NOS) in human SO; (b) characterize the pharmacology of S-nitroso-N-acetylcysteine (SNAC), an exemplary S-nitrosothiol, on SO motility in a rabbit model; and (c) study the effects of topical SNAC on SO motility in humans. Immunocytochemical and histochemical identification of NOS was performed in human SO. The pharmacologic response of SNAC was defined in isolated rabbit SO using a standard bioassay. Topical SNAC was then applied to the duodenal papilla in patients undergoing endoscopic retrograde cholangiopancreatography (ERCP) and biliary manometry. NOS was localized to nerve fibers and bundles of the SO in rabbits and humans. SNAC inhibited spontaneous motility (frequency and amplitude) as well as acetylcholine-induced elevations in SO basal pressure in the rabbit model. In patients undergoing ERCP and biliary manometry, topical SNAC inhibited SO contraction freqency, basal pressure, and duodenal motility. NOS is localized to neural elements in human SO, implicating a role for NO in regulating SO function. Supporting this concept, SNAC is an inhibitor of SO and duodenal motility when applied topically to humans during ERCP. Our data suggest a novel clinical approach using local NO donors to control gastrointestinal motility and regulate sphincteric function.

Membrane glycoconjugates expressed on sheep airway epithelium

In mammalian lung, selective airway inflammatory reactions have been associated with viral infections, transplant rejection, and autoimmune diseases. Although the molecular basis for this selective reactivity is unknown, the importance of carbohydrates in immunologic processes suggests a potential role for membrane glycoconjugates in tissue-specific inflammatory reactions. In the present work we examined a panel of 39 lectins for their pattern of reactivity in the peripheral airways of the sheep lung. The size of the panel facilitated a comprehensive description of the glycoconjugate localization on the airway epithelium. Four lectins (agglutinins for Helix aspersa, Psophocarpus tetragonolobus, Trichosanthes kirilowii, and Griffonia simplifolia II) revealed selective reactivity with the small airway epithelium. On lectin Western blotting, these four lectins demonstrated a common low molecular weight banding profile that was distinct from control lectins. The histochemical staining patterns and Western blotting profiles provided evidence for the selective expression of membrane glycoconjugates in the peripheral airways of the sheep lung.

Effects of chronic airway inflammation on the activity and enzymatic inactivation of neuropeptides in guinea pig lungs

The effects of airway inflammation induced by chronic antigen exposure on substance P (SP)-induced increases and vasoactive intestinal peptide (VIP)-induced decreases in airway opening pressure (Pao), and the recovery of intact and hydrolyzed radiopeptide were studied in tracheally perfused guinea pig lungs. SP (10(-6) mol/kg) induced a significantly greater increase in Pao in lungs from antigen-exposed (30 +/- 5 cm H2O) than saline-exposed animals (15 +/- 1 cm H2O, P < 0.05). Significantly more intact 3H-SP and significantly less 3H-SP 1-7, a neutral endopeptidase (NEP) hydrolysis product, were recovered from the lung effluent of antigen-exposed than saline-exposed animals (P < 0.05). Injection of VIP (10(-9) mol/kg) induced significantly more pulmonary relaxation in saline-exposed compared with antigen-exposed lungs (62 +/- 4%, P < 0.001). In contrast to effluent from saline-exposed animals, lung effluent from antigen-exposed lungs contained less intact VIP, increased amounts of a tryptic hydrolysis product, and no products consistent with the degradation of VIP by NEP. These data indicate that inflamed lungs are more sensitive to the contractile effects of SP because it is less efficiently degraded by NEP and are less sensitive to the relaxant effects of VIP because it is more efficiently degraded by a tryptic enzyme. Changes in airway protease activity occur with allergic inflammation and may contribute to airway hyperresponsiveness.

Neutrophil and nonneutrophil-mediated injury in intestinal ischemia-reperfusion

OBJECTIVE

The role of polymorphonuclear neutrophils (PMN) was examined in local and remote organ injury after intestinal ischemia-reperfusion.

SUMMARY BACKGROUND DATA

PMN have been found to mediate the local injury in low flow intestinal ischemia-reperfusion. However, in complete intestinal ischemia-reperfusion, prevention of PMN adhesion by monoclonal antibodies to CD11b and CD18 reduces remote but not local intestinal injury. The role of PMN was further investigated in this setting.

METHODS

In a rat model of 1-hour complete intestinal ischemia and 4-hour reperfusion. PMN were manipulated in the following four ways: (1) inhibition of oxygen-free radicals using manganese superoxide dismutase and catalase (SOD/CAT), (2) antagonism of PMN elastase using secretory leukocyte protease inhibitor (SLPI), (3) neutropenia using PMN antisera, and (4) inhibition of activation and adhesion using interleukin-1 receptor antagonist (IL-1ra) and tumor necrosis factor binding protein (TNFbp). Lung injury was quantified by the pulmonary permeability index, which is the ratio of bronchoalveolar lavage to blood concentration of radiolabeled bovine serum albumin, and PMN sequestration by myeloperoxidase (MPO) activity. Liver injury was estimated by PMN counts using quantitative histologic examination and by serum glutamic pyruvic transaminase (SGPT). Local injury was quantified by MPO activity and histologic grading.

RESULTS

Neutropenia reduced the pulmonary permeability 80% from 11.0 +/- 0.5 x 10(-3) with saline treatment to 5.50 +/- 0.12 x 10(-3); IL-1ra, to 5.62 +/- 0.44 x 10(-3); and TNFbp, to 4.32 +/- 0.18 x 10(-3) (all p < 0.05). Pulmonary MPO rose from 0.03 +/- 0.01 U/g to 0.25 +/- 0.03 U/g (p < 0.05). This was reduced by neutropenia, 0.01 +/- 0.003 U/g, but not by inhibition of oxygen-free radicals or PMN elastase. IL-1ra inhibited PMN sequestration, reducing MPO to 0.12 +/- 0.01 (p < 0.05). Liver injury was 60% dependent on PMN. Ischemia-reperfusion increased SGPT from 20.3 +/- 0.7 IU/L in the sham-treated animals to 97.0 +/- 3.1 IU/L in the experimental animals. Neutropenia reduced this to 48.1 +/- 3.9 IU/L; IL-1ra, to 44.7 +/- 3.7 IU/L; SOD/CAT, to 64.0 +/- 3.38 IU/L; and SLPI, to 57.1 +/- 3.4 IU/L (p < 0.05 in all cases). Local injury was severe and unaffected by manipulation of the PMN.

CONCLUSIONS

These data suggest that PMN and their products mediate most of the lung, part of the liver, and none of the local gut injury after intestinal ischemia-reperfusion.

Nitric oxide synthase in human and rat lung: immunocytochemical and histochemical localization

Nitric oxide synthase (NOS) produces nitric oxide, a mediator of potential importance in numerous physiologic and inflammatory processes in the lung. We localized constitutive NOS (c-NOS) and inducible NOS (i-NOS) within lung tissue by immunoperoxidase labeling with specific antibodies or by histochemical demonstration of the characteristic NADPH diaphorase activity of NOS. We analyzed human airway (n = 4) or parenchyma (n = 10) specimens obtained from uninvolved areas of surgical tumor resections. We also studied human fetal lung samples (n = 6) and normal or inflamed (16 h after intratracheal LPS instillation) rat lung tissue. Immunostaining with anti-c-NOS identified c-NOS antigen in rat lung nerves, endothelium, and airway epithelium. Normal or inflamed rat macrophages were not stained. Human nerve elements and large-vessel endothelium showed immunostaining with the anti-c-NOS, but no labeling of the airway or alveolar epithelium was seen. Immunostaining with anti-i-NOS showed strong labeling of rat macrophages after LPS treatment, in vivo or in vitro, while normals were negative. Human alveolar macrophages were occasionally positive for i-NOS, especially in areas of chronic inflammation, which also showed focal immunolabeling of endothelium. Uniform labeling of epithelium in large, cartilaginous airways was found with anti-i-NOS in both human bronchi and normal rat trachea samples, suggesting a constitutive role for a NOS that shares epitope(s) with or is highly homologous to the inducible, macrophage type of NOS. Histochemical staining for NADPH diaphorase activity was consistent with immunolocalization of NOS antigens.(ABSTRACT TRUNCATED AT 250 WORDS)

Particle opsonization and lung macrophage cytokine response. In vitro and in vivo analysis

Inhaled inert particles and organisms cause a spectrum of pulmonary responses, ranging from minimal changes to marked acute inflammation. During ingestion and clearance of such particles, alveolar macrophages (AM) can initiate pulmonary inflammation by production of TNF and neutrophil chemoattractant cytokines. We tested the role of opsonization in determining the AM response to ingestion of inert particles in vitro and in vivo. As measures of AM activation after phagocytosis in vitro, we measured release of TNF and mRNA expression for the platelet-factor 4 family neutrophil chemoattractants, KC and macrophage-inflammatory protein-2 (MIP-2). Using albumin-coated fluorescent latex particle as phagocytic targets, we found a marked release of TNF by AM ingesting particles opsonized with antialbumin IgG, although uptake of similar numbers of unopsonized particles caused little or no release (e.g., 4648 +/- 1147 pg/ml, opsonized beads vs 576 +/- 205 unopsonized, 10:1 particle:cell ratio, n = 4, mean +/- SD). Flow cytometry confirmed equal uptake of the two particle types. Northern analysis of AM mRNA showed marked induction of KC and MIP-2 mRNA after ingestion of opsonized particles only. Instillation of opsonized particles into hamster lungs caused a marked neutrophil influx, although unopsonized particles did not. TNF was elevated in lavage fluid after instillation of opsonized particles, but not after unopsonized beads (92.7 +/- 136 pg/ml opsonized, n = 7 vs 1.3 +/- 3.6 unopsonized, n = 6). KC and MIP-2 mRNA were induced in lavaged cells after instillation of opsonized but not after unopsonized particles or vehicle control. The nature of particle interaction with the AM surface during phagocytosis determines the subsequent AM response. Although many unopsonized inert particles are ingested with minimal AM activation, specific opsonization of pathogens or non-specific adsorption of Ig onto other particles may activate AM and lead to pulmonary inflammation.

Particle opsonization and lung macrophage cytokine response. In vitro and in vivo analysis

Inhaled inert particles and organisms cause a spectrum of pulmonary responses, ranging from minimal changes to marked acute inflammation. During ingestion and clearance of such particles, alveolar macrophages (AM) can initiate pulmonary inflammation by production of TNF and neutrophil chemoattractant cytokines. We tested the role of opsonization in determining the AM response to ingestion of inert particles in vitro and in vivo. As measures of AM activation after phagocytosis in vitro, we measured release of TNF and mRNA expression for the platelet-factor 4 family neutrophil chemoattractants, KC and macrophage-inflammatory protein-2 (MIP-2). Using albumin-coated fluorescent latex particle as phagocytic targets, we found a marked release of TNF by AM ingesting particles opsonized with antialbumin IgG, although uptake of similar numbers of unopsonized particles caused little or no release (e.g., 4648 +/- 1147 pg/ml, opsonized beads vs 576 +/- 205 unopsonized, 10:1 particle:cell ratio, n = 4, mean +/- SD). Flow cytometry confirmed equal uptake of the two particle types. Northern analysis of AM mRNA showed marked induction of KC and MIP-2 mRNA after ingestion of opsonized particles only. Instillation of opsonized particles into hamster lungs caused a marked neutrophil influx, although unopsonized particles did not. TNF was elevated in lavage fluid after instillation of opsonized particles, but not after unopsonized beads (92.7 +/- 136 pg/ml opsonized, n = 7 vs 1.3 +/- 3.6 unopsonized, n = 6). KC and MIP-2 mRNA were induced in lavaged cells after instillation of opsonized but not after unopsonized particles or vehicle control. The nature of particle interaction with the AM surface during phagocytosis determines the subsequent AM response. Although many unopsonized inert particles are ingested with minimal AM activation, specific opsonization of pathogens or non-specific adsorption of Ig onto other particles may activate AM and lead to pulmonary inflammation.

Rapamycin treatment depresses intragraft expression of KC/MIP-2, granzyme B, and IFN-gamma in rat recipients of cardiac allografts

Rapamycin (RPM) treatment prevents accelerated rejection of cardiac allografts in sensitized rats. The prominent feature of this brisk 24-h rejection, which includes a panoply of both cellular and humoral host immune responses, is a massive infiltration of rejecting grafts with neutrophils. In this study we tested the hypothesis that RPM-mediated therapeutic effects on accelerated rejection may be linked to decreased expression of protein encoded by gro/melanoma-growth stimulatory activity gene (KC) and macrophage inflammatory protein-2 (MIP-2) genes, the operational rat homologues of the human intercrine-alpha cytokines with proinflammatory IL-8-like neutrophil activation/chemotactic properties. The induction of these genes was then correlated with mRNA profiles encoding for Th1-selective IFN-gamma and CTL-specific granzyme B proteins. Northern blot analysis of RNA from cardiac allografts of sensitized untreated recipients, revealed maximal levels of KC and MIP-2 mRNA at 3 to 6 h after transplantation. In contrast, IFN-gamma mRNA, which was at most very weakly expressed at 3 h, peaked between 6 to 12 h. As with IFN-gamma, granzyme B transcripts were undetectable at 3 h, but peaked around the time of actual graft rejection at 24 h. RPM therapy abrogated accelerated rejection and prolonged cardiac allograft survival to ca. 46 days. This effect was associated with markedly reduced expression of KC and MIP-2 mRNA in the first 24 h as well as at 7 and 34 days after transplantation. Moreover, RPM completely blocked intragraft appearance of granzyme B and IFN-gamma mRNA in long term cardiac allografts. Immunohistologic analysis has revealed that accelerated rejection was associated with extensive neutrophil infiltration, which peaked at 18 to 24 h. At this time, leukocytes and endothelium were intensely stained for IL-8 and IFN-gamma antibodies. In contrast, the allografts from RPM-treated hosts showed essentially no neutrophil infiltration and minor, focal staining for IL-8 and IFN-gamma. This study demonstrates an association between the early expression of genes for proinflammatory IL-8-dependent neutrophil chemotactic activity, and later expression of genes associated with activation/effector activity of CTL and NK cells. It also documents a novel effect of RPM in vivo, which results in the suppression of intragraft IL-8-like and CTL-dependent mRNA/protein production and diminished neutrophil infiltration; these may contribute to the striking efficacy of RPM therapy in sensitized graft recipients.

Rapamycin treatment depresses intragraft expression of KC/MIP-2, granzyme B, and IFN-gamma in rat recipients of cardiac allografts

Rapamycin (RPM) treatment prevents accelerated rejection of cardiac allografts in sensitized rats. The prominent feature of this brisk 24-h rejection, which includes a panoply of both cellular and humoral host immune responses, is a massive infiltration of rejecting grafts with neutrophils. In this study we tested the hypothesis that RPM-mediated therapeutic effects on accelerated rejection may be linked to decreased expression of protein encoded by gro/melanoma-growth stimulatory activity gene (KC) and macrophage inflammatory protein-2 (MIP-2) genes, the operational rat homologues of the human intercrine-alpha cytokines with proinflammatory IL-8-like neutrophil activation/chemotactic properties. The induction of these genes was then correlated with mRNA profiles encoding for Th1-selective IFN-gamma and CTL-specific granzyme B proteins. Northern blot analysis of RNA from cardiac allografts of sensitized untreated recipients, revealed maximal levels of KC and MIP-2 mRNA at 3 to 6 h after transplantation. In contrast, IFN-gamma mRNA, which was at most very weakly expressed at 3 h, peaked between 6 to 12 h. As with IFN-gamma, granzyme B transcripts were undetectable at 3 h, but peaked around the time of actual graft rejection at 24 h. RPM therapy abrogated accelerated rejection and prolonged cardiac allograft survival to ca. 46 days. This effect was associated with markedly reduced expression of KC and MIP-2 mRNA in the first 24 h as well as at 7 and 34 days after transplantation. Moreover, RPM completely blocked intragraft appearance of granzyme B and IFN-gamma mRNA in long term cardiac allografts. Immunohistologic analysis has revealed that accelerated rejection was associated with extensive neutrophil infiltration, which peaked at 18 to 24 h. At this time, leukocytes and endothelium were intensely stained for IL-8 and IFN-gamma antibodies. In contrast, the allografts from RPM-treated hosts showed essentially no neutrophil infiltration and minor, focal staining for IL-8 and IFN-gamma. This study demonstrates an association between the early expression of genes for proinflammatory IL-8-dependent neutrophil chemotactic activity, and later expression of genes associated with activation/effector activity of CTL and NK cells. It also documents a novel effect of RPM in vivo, which results in the suppression of intragraft IL-8-like and CTL-dependent mRNA/protein production and diminished neutrophil infiltration; these may contribute to the striking efficacy of RPM therapy in sensitized graft recipients.

Leukocytes mediate acid aspiration-induced multiorgan edema

BACKGROUND

Acid aspiration leads to lung injury characterized by polymorphonuclear neutrophil leukocytes (PMN) sequestration and edema. This study investigates whether localized acid aspiration leads to activation of circulating PMN and triggers both local and remote PMN sequestration and whether these cells are responsible for increase in pulmonary permeability and systemic organ edema.

METHODS

Rats pretreated with intravenous saline solution or rendered neutropenic (nitrogen mustard or antineutrophil serum) underwent tracheostomy and insertion of a cannula into a lung segment. This was followed by instillation of either 0.1 N HCl or saline solution.

RESULTS

After 30 minutes leukopenia was noted (2650 white blood cells/mm3) in saline-treated, acid-lavaged rats, and circulating PMN produced H2O2 (20 femtomole dichlorofluorescein/PMN compared with 3 femtomole in control animals (both, p < 0.05). PMN were progressively sequestered in the nonaspirated lung, the heart, and kidney. Permeability and edema developed in the lungs and systemic organs. In neutropenic rats there was a reduction of aspiration-induced thromboxane B2 and leukotriene B4 synthesis (p < 0.05), decrease in lung wet to dry weight and protein level in bronchoalveolar lavage of the aspirated and nonaspirated lungs, and reduction in myeloperoxidase activity in the heart and kidney and in wet to dry weight of these organs (all, p < 0.05).

CONCLUSIONS

These data indicate that localized acid aspiration activates circulating neutrophils and promotes their sequestration in the lungs and systemic organs. These cells are largely responsible for the multisystem organ edema.

Abnormal contractile function due to induction of nitric oxide synthesis in rat cardiac myocytes follows exposure to activated macrophage-conditioned medium

The mechanism by which soluble mediators of immune cell origin depress myocardial contractility, either globally as in systemic sepsis, or regionally in areas of inflammatory myocardial infiltrates, remains unclear. When freshly isolated ventricular myocytes from adult rat hearts were preincubated for at least 24 h in medium conditioned by endotoxin (LPS)-activated rat alveolar macrophages, their subsequent inotropic response to the beta-adrenergic agonist isoproterenol was reduced from 225 +/- 19% to 155 +/- 10% of the baseline amplitude of shortening (mean +/- SEM, P < 0.05). Neither baseline contractile function nor the contractile response to high extracellular calcium were affected. To determine whether an endogenous nitric-oxide (NO)-signaling pathway within ventricular myocytes was responsible for their decreased responsiveness to isoproterenol, the L-arginine analogue L-NMMA was added to the preincubation medium. While L-NMMA did not affect baseline contractile function or the response of control myocytes to isoproterenol, it completely restored the positive inotropic response to isoproterenol in myocytes preincubated in LPS-activated macrophage medium. Release of NO by ventricular myocytes following exposure to activated macrophage medium was detected as an increase in cGMP content in a reporter-cell (RFL-6) bioassay and also as increased nitrite content in myocyte-conditioned medium. Thus, the depressed contractile response of adult rat ventricular myocytes to beta-adrenergic agonists by a 24-h exposure to soluble inflammatory mediators is mediated at least in party by induction of an autocrine NO signaling pathway.

Lavage with leukotriene B4 induces lung generation of tumor necrosis factor-alpha that in turn mediates neutrophil diapedesis

In experimental models of acute respiratory failure, leukotriene (LT) B4 is generated in the lungs, followed by a 2- to 3-hour delay before there is substantial neutrophil (PMN) accumulation and increased permeability. This study tests whether lavage with LTB4 induces tumor necrosis factor (TNF) synthesis by the lungs that in turn mediates PMN diapedesis. Anesthetized rats underwent lavage with 0.1 ml LTB4 (10(-6) mol/L) into a lung segment. This led to localized TNF synthesis measured in bronchoalveolar lavage fluid with peak concentrations of 580 pg/ml after 1 1/2 hours and 120 pg/ml after 3 hours. These values were higher than after lavage with 0.1 ml saline solution: 0.7 and 4.3 pg/ml, respectively (both p < 0.05). There was a delay before PMN accumulated in bronchoalveolar lavage fluid (x 10(4)). After 30 minutes, the numbers were 2.2 PMN/ml, whereas at 4 hours there was a rise to 40 PMN/ml and at 5 hours 60 PMN/ml, higher than after saline lavage (all p < 0.05). Pretreatment of rats by lavage into airways with actinomycin D, 12 ng in 0.1 ml, minimized LTB4-induced TNF synthesis after 1 1/2 and 3 hours (38 and 51 pg/ml), as well as the delayed diapedesis after 4 hours (12 PMN/ml) (all p < 0.05). Similarly, pretreatment of other rats by lavage with TNF-alpha antiserum (rabbit antimurine), but not normal serum, limited LTB4-induced diapedesis (13 PMN/ml) (p < 0.05). Interestingly, administration of the protein synthesis inhibitor actinomycin D by lavage 10 minutes after LTB4 did not prevent TNF generation after 1 1/2 or 3 hours (490 and 440 pg/ml). However, this agent did limit PMN diapedesis after 4 hours (14 PMN/ml) (p < 0.05), an event possibly caused by limiting later synthesis of endothelial adhesion proteins, a thesis consistent with the findings that pretreatment of rats by lavage with actinomycin D was without any effect on N-formyl-methionyl-phenylalanine (10(-8) mol/L)-induced diapedesis. This agent is known to induce PMN migration without need for synthesis of endothelial adhesion proteins. The data indicate that lavage with LTB4 induces local TNF-alpha generation that in turn mediates a delayed PMN diapedesis. This event is likely regulated by endothelial synthesis of adhesion proteins.

The effect of aerosolized recombinant human granulocyte macrophage colony-stimulating factor on lung leukocytes in nonhuman primates

The number and function of myeloid cells in the lungs are critical determinants of health and disease. To examine whether these cells can be modulated in vivo by a colony-stimulating factor (CSF), recombinant human granulocyte macrophage-CSF (GM-CSF) was given to cynomolgus monkeys by either continuous intravenous infusion (7,200 U/kg/day) for 2 wk or by aerosol exposure to 10(7) U on 1 or 2 consecutive days. At intervals after the initiation of GM-CSF administration, animals underwent bronchoalveolar lavage (BAL) and had peripheral blood sampled to characterize changes in lung and circulating phagocytic cells. Compared with animals exposed to bovine serum albumin, there was an increase in the total number of BAL cells retrieved. This increase was greatest in animals receiving aerosolized GM-CSF, and it was the result of more macrophages and neutrophils. Both lung macrophages and blood neutrophils from animals exposed to aerosolized GM-CSF exhibited an augmented respiratory burst in response to phorbol myristate acetate. Lung macrophages from GM-CSF-exposed animals exhibited increased capacity to bind and/or ingest opsonized and unopsonized Staphylococcus aureus. Despite functional activation of lung phagocytic cells, biochemical analyses of BAL fluid for markers of lung injury revealed an increase in only some parameters in the GM-CSF group. Intravenous administration of GM-CSF had the expected effect on augmenting the number of myeloid cells in the bloodstream. Aerosolized GM-CSF produced a transient effect on circulating myeloid cell number between 3 and 5 days after exposure.(ABSTRACT TRUNCATED AT 250 WORDS)

Reactive oxygen in skeletal muscle. I. Intracellular oxidant kinetics and fatigue in vitro

We hypothesized that muscle fiber bundles produce reactive oxygen intermediates and that reactive oxidant species contribute to muscular fatigue in vitro. Fiber bundles from rat diaphragm were mounted in chambers containing Krebs-Ringer solution. In studies of intracellular oxidant kinetics, bundles were loaded with 2',7'-dichlorofluorescin, a fluorochrome that emits at 520 nm when oxidized; emissions were quantified using a fluorescence microscope. Emissions from unstimulated muscles increased over time (P < 0.001). Accumulation of fluorescence was slowed by addition of catalase (P < 0.001) or superoxide dismutase (P < 0.001) and was accelerated by repetitive muscular contraction (P < 0.05). To determine effects of reactive oxygen intermediates on fatigue, curarized bundles were stimulated to contract isometrically; force was measured. Catalase, superoxide dismutase, and dimethyl sulfoxide were screened for effects on low- and high-frequency fatigue. Antioxidants inhibited low-frequency fatigue [after 5 min of repetitive contractions, force at 30 Hz was 20% greater than control (P < 0.015)] and increased the variability of fatigue at 30 Hz (P < 0.03). Antioxidants did not alter high-frequency (200-Hz) fatigue. We conclude that 1) diaphragm fiber bundles produce reactive oxygen intermediates, including O2-. and H2O2; 2) muscular contraction increases intracellular oxidant levels; and 3) reactive oxygen intermediates promote low-frequency fatigue in this preparation.

Expression of macrophage inflammatory protein-2 and KC mRNA in pulmonary inflammation

This study sought to test the hypothesis that expression of mRNA for two cytokines, macrophage inflammatory protein-2 (MIP-2) and the KC gene product, is induced in rat lung cells during inflammatory responses in vitro and in vivo. Macrophage inflammatory protein-2 and KC are members of the platelet-factor 4 (PF-4) cytokine superfamily that cause marked neutrophil chemotaxis and activation in vitro. To investigate expression of the genes for MIP-2 and KC in rat models of lung injury, cDNA probes for these cytokines in the rat were made from polymerase chain reaction (PCR) products generated using mouse sequence-derived primers. Sequence analysis of these cDNAs showed marked homology to known murine sequences (89% and 92% MIP-2 and KC, respectively). These cDNAs were first used to study the expression of these two genes in rat alveolar macrophages (AMs) in vitro by Northern blot hybridization. Lipopolysaccharide (LPS) treatment of rat AMs in vitro caused marked increases in mRNA for both KC and MIP-2 within 30 minutes, which persisted through the 6 hours measured. To study expression during inflammation in vivo, rats were treated with LPS by intratracheal instillation. Bronchoalveolar lavage (BAL) cells and whole trachea homogenates were analyzed. There was a marked and rapid increase in MIP-2 and KC mRNA levels within both BAL cells and trachea homogenates after LPS instillation. The results support the hypothesis that MIP-2 and KC cytokines contribute to neutrophil chemotaxis and activation in this rat model of acute pulmonary inflammation.

Mast cells and leukotrienes mediate neutrophil sequestration and lung edema after remote ischemia in rodents

Reperfusion of ischemic hindlimbs leads to leukotriene B4 (LTB4) and polymorphonuclear neutrophil (PMN)-dependent lung injury. Pulmonary mast cells are capable of synthesizing LTB4 and are potential mediators of this inflammatory response. This study tests their role in PMN sequestration and pulmonary edema after hindlimb ischemia. Anesthetized, mast cell-sufficient mice (n = 8) or their congeneic mast cell-deficient strain (n = 8) were subjected to 3 hours of hindlimb ischemia. After another 3 hours of reperfusion, plasma LTB4 levels rose to 651 pg/ml, higher than sham ischemic control (n = 8) values of 202 pg/ml (p less than 0.05). At this time there was sequestration of neutrophils in the pulmonary microcirculation (54 PMN/10 high-power fields [HPF]) and an increase in lung wet/dry weight ratio (W/D) of 4.4. Both these values were higher (p less than 0.05) than those in sham ischemic animals that showed sequestration of 18 PMN/10 HPF and a lung W/D of 3.1. In contrast, mast cell-deficient mice showed an attenuation of ischemia- and reperfusion-induced rise in plasma LTB4 (507 pg/ml), fewer sequestered neutrophils (34 PMNs/10 HPF), and a reduction in lung W/D to 3.9 (all p less than 0.05). To test the role of lung LTB4 in determining PMN sequestration, rats (n = 78) were subjected to 3 hours of hindlimb ischemia. After 3 hours of reperfusion, plasma and bronchoalveolar lavage (BAL) LTB4 concentrations rose to 956 and 211 pg/ml, respectively--higher than sham values of 460 and 121 pg/ml (both p less than 0.05). After 4 hours, plasma LTB4 levels had returned to baseline, whereas BAL LTB4 had increased further to 658 pg/ml, indicating lung origin. Treatment of other rats by localized lung lavage of the lipoxygenase inhibitor diethylcarbamazine (80 mg/kg in 0.1 ml twice) prevented the ischemia- and reperfusion-induced rise in BAL LTB4 (267 pg/ml) and limited local neutrophil sequestration (from 51 PMN/10 HPF after saline aspiration to 36 PMN/10 HPF) and lung W/D (from 4.5 to 4.1) (all p less than 0.05). The data indicate that after hindlimb ischemia pulmonary mast cells and localized LTB4 synthesis mediate, in part, the lung inflammatory response.

Adherent neutrophils mediate permeability after atelectasis

Re-expansion of atelectatic lung is associated with increased permeability. This study tests whether neutrophils mediate this event. Right middle lobar atelectasis was induced in anesthesized rabbits (n = 18) by intraluminal obstruction of the bronchus after a 20-minute ventilation with 100% O2. After 1 hour of bronchial obstruction and 20 minutes after lobar re-expansion, leukopenia was noted, 2870 +/- 210 white blood cells (WBC)/mm3, relative to control animals treated with a noninflated balloon catheter, 6500 +/- 410 WBC/mm3 (p less than 0.05). Three hours after re-expansion, neutrophils were sequestered in the previously atelectatic region 78 +/- 7 polymorphonuclear leukocytes (PMN)/10 high-power field (HPF), as well as in nonatelectatic areas, 40 +/- 3 PMN/10 HPF, higher than control values of 26 +/- 3 PMN/10 HPF (p less than 0.05). In the atelectatic region, neutrophil sequestration was associated with increased protein concentration in lobar bronchoalveolar lavage (BAL) of 1370 +/- 100 micrograms/mL, higher than control values of 270 +/- 20 micrograms/mL (p less than 0.05). Reexpansion also induced increases in lung wet-to-dry weight ratio (W/d) of 6.2 +/- 0.2, higher than control values of 4.3 +/- 0.1 (p less than 0.05). Rendering rabbits neutropenic (n = 18) (0 to 4 PMN/mm3) limited the atelectasis-induced protein accumulations in BAL (520 +/- 60 micrograms/mL) and increase in lung W/d (5.2 +/- 0.1) (both p less than 0.05). Intravenous (I.V.; treatment of another group (n = 18) with an anti-CD 18 monoclonal antibody (R 15.7, 1 mg/kg) before balloon deflation prevented leukopenia (6550 +/- 560 WBC/mm3), minimized neutrophil sequestration (36 +/- 2 PMN/10 HPF), and attenuated protein leak (710 +/- 95 micrograms/mL) and the increased lung W/d (5.6 +/- 0.1) (all p less than 0.05). A final atelectatic group (n = 9) was treated I.V. with the anti-intercellular adhesion molecule-1 monoclonal antibody (RR 1/1, 1 mg/kg), which also prevented leukopenia and showed similar protection of microvascular barrier function. These data indicate that adherent neutrophils in large part mediate lung permeability and edema after atelectasis and re-expansion. Adhesion receptors of both neutrophils and endothelial cells regulate this event.

Reactive oxygen species and elastase mediate lung permeability after acid aspiration

Acid aspiration leads to increased neutrophil (PMN) oxidative metabolism, an event associated with lung leukosequestration and permeability increase. Neutropenia protected the vascular barrier function against acid injury. This study tests whether active oxygen species and elastase (which are presumably released by adherent PMNs) affect the microvascular barrier. Anesthetized rats underwent tracheostomy and insertion of a cannula into a lung segment. This was followed by localized instillation of 0.1 N HCl (n = 18) or saline (n = 18). Sequestration of PMNs in acid-aspirated and nonaspirated segments was 77 and 46 PMNs/high-power field (HPF), respectively, which was higher than control values of 11 and 8 PMNs/10 HPF in saline-aspirated and nonaspirated regions (P less than 0.05). Acid aspiration was associated with increased protein concentration in bronchoalveolar lavage (BAL) fluid to 3,550 and 2,900 micrograms/ml in the aspirated and nonaspirated lungs, respectively, which were higher than control values of 420 and 400 micrograms/ml (P less than 0.05). Acid aspiration also led to increased lung wet-to-dry weight ratios (W/D) of 6.6 and 5.4, which were higher than control values of 3.4 and 3.3 (P less than 0.05). Intravenous treatment of rats (n = 18) 90 min after aspiration with scavengers of reactive oxygen species, superoxide dismutase (1,500 U/kg), and catalase (5,000 U/kg), both conjugated to polyethylene glycol, did not reduce PMN sequestration but attenuated acid aspiration-induced increase in protein accumulation in BAL fluid in the aspirated and nonaspirated segments (990 and 610 micrograms/ml) as well as the increased lung W/D (4.6 and 4.0; all P less than 0.05).(ABSTRACT TRUNCATED AT 250 WORDS)

Role of neutrophil adherence receptors (CD 18) in lung permeability following lower torso ischemia

Ischemia and reperfusion of the lower torso lead to leukotriene- and neutrophil (PMN)-dependent lung injury characterized by lung PMN sequestration, increased permeability, and noncardiogenic edema. It is thought that PMNs require adhesion to endothelium to alter barrier function. This study tests the role of CD 18, the PMN adherence receptor, in mediating lung permeability after lower torso ischemia and reperfusion. Anesthetized rabbits (n = 9) underwent 3 hours of bilateral hind limb ischemia. Ten minutes after the release of the tourniquets, plasma leukotriene B4 levels increased to 395 +/- 85 pg/ml, higher than 129 +/- 35 pg/ml in controls (n = 9, p less than 0.01). At this time there was a reduction in circulating white blood cells (x 10(3)), 3.56 +/- 0.49/mm3 relative to 6.07 +/- 0.61/mm3 in controls (p less than 0.01). PMNs were sequestered in the hind limbs, indicated by increased myeloperoxidase activity of 1.06 +/- 0.19 units/g compared with 0.56 +/- 0.09 units/g in controls (p less than 0.05). Four hours after tourniquet release, PMNs were sequestered in the lungs, 52 +/- 4 PMNs per 10 high-power fields, a value higher than 31.5 +/- 3 PMNs per 10 high-power fields in controls; bronchoalveolar lavage fluid protein content increased to 554 +/- 90 micrograms/ml relative to 277 +/- 46 micrograms/ml in controls; and there was lung edema, measured by increased wet weight-to-dry weight ratios of 5.19 +/- 0.10, higher than 4.29 +/- 0.21 in controls (all p less than 0.01).(ABSTRACT TRUNCATED AT 250 WORDS)

Rat KC cDNA cloning and mRNA expression in lung macrophages and fibroblasts

We have isolated and sequenced overlapping cDNA clones for rat KC*. The 0.93 kb cDNA has a single open reading frame of 288 nucleotides, and substantial sequence identity with the platelet-factor 4 family members mouse KC, hamster gro, and human gro. Using cloned cDNA as a probe, expression of KC mRNA in lavaged rat alveolar macrophages (AMs) increased after lipopolysaccharide (LPS) treatment. We also studied expression in vitro by a rat fetal lung fibroblast cell line, RFL-6. Expression of KC mRNA in RFL-6 cells increased after treatment with interleukin 1 or with conditioned medium from rat AMs treated with LPS.

Characterization of colony stimulating factor activity in the human respiratory tract. Comparison of healthy smokers and nonsmokers

The number and function of pulmonary macrophages are critical to lung homeostasis. To characterize factors normally present in the human respiratory tract that can influence these parameters, bronchoalveolar lavage (BAL) fluid obtained from healthy smokers and nonsmokers was assayed for the presence of colony-stimulating factor (CSF) activity. Concentrated BAL fluid from both populations was capable of inducing incorporation of [3H]thymidine by murine macrophages. The mean increase (+/- SEM) in incorporation over control cultures not exposed to BAL fluid was 0.98 +/- 0.22 for nonsmokers and 2.25 +/- 1.19 for smokers (p less than 0.001). This CSF bioactivity was characterized as macrophage-CSF (M-CSF) by virtue of its action on murine macrophages, the detection of M-CSF protein by a specific ELISA assay, and the inability to detect other macrophage-active CSFs, granulocyte macrophage-CSF (GM-CSF) and interleukin-3 (IL-3), in a proliferation assay employing the MO7E cell line. There was a significant correlation between macrophage number in BAL samples and measureable bioactivity among both smokers and nonsmokers (r = 0.763; p less than 0.001). This suggested that macrophages themselves are a source of the M-CSF detected in BAL fluid. To examine this possibility, slot-blot analysis of macrophage RNA was performed. Constitutive expression of comparable amounts of M-CSF mRNA and protein was found in cells from both smokers and nonsmokers. However, macrophages obtained from a randomly selected subset of four smokers but none of five nonsmokers exhibited increased production of M-CSF in response to an inflammatory stimulus, lipopolysaccharide (LPS; 5 ng/ml). M-CSF added to macrophage cultures was degraded by nonsmokers' cells as expected over 24 h.(ABSTRACT TRUNCATED AT 250 WORDS)

Synergism between leukotriene B4 and thromboxane A2 in mediating acid-aspiration injury

Acid aspiration leads to thromboxane-dependent lung neutrophil sequestration associated with microvascular permeability increase. Leukotriene B4 (LTB4) is postulated to be a cofactor in the thromboxane-induced inflammatory response. This study tests the interaction between LTB4 and thromboxane, focusing on LTB4 induction of thromboxane-dependent lung neutrophil sequestration after acid aspiration. Anesthetized rats underwent tracheostomy and insertion of a cannula in a left lung segment. This was followed by instillation of either 0.1 ml 0.1N hydrochloric acid (n = 18) or 0.1 ml saline in control rats (n = 18). When assayed at 3 hours, acid aspiration led to increased plasma levels of LTB4 and thromboxane B2 (TxB2), higher than control values (p less than 0.05). The rise in plasma LTB4 was correlated (p less than 0.05; r = 0.83) with sequestration of neutrophils in the nonaspirated lung. The entrapment of thromboxane-dependent lung neutrophil was associated with an increase in protein concentration in bronchoalveolar lavage of the aspirated and nonaspirated sides and an increase in lung wet to dry weight ratio. Pretreatment of other rats (n = 18) with the lipoxygenase inhibitor diethylcarbamazine IV prevented an aspiration-induced rise in plasma LTB4 and TxB2. Further, there was an attenuation of lung leukosequestration and protein leak in bronchoalveolar lavage and lung edema (all p less than 0.05). Pretreatment of other rats (n = 12) with the leukotriene receptor antagonist FPL 55712 IV did not prevent the aspiration-induced rise in LTB4 or TxB2, but otherwise was as effective as diethylcarbamazine in preventing injury. Finally, other hydrochloric acid-aspirated rats (n = 8) were pretreated intravenously with the thromboxane synthetase inhibitor OKY 046 or the thromboxane receptor antagonist SQ 29548. Both agents limited the aspiration-induced rise in plasma LTB4 (p less than 0.05). The data indicate that localized acid aspiration induces synthesis of LTB4 and thromboxane A2. Inhibition of either leukotriene or thromboxane will limit PMN adhesion and increased lung permeability.

Interleukin-2 induces early multisystem organ edema mediated by neutrophils

Interleukin-2 (IL-2), an agent known to activate neutrophils (PMN) with thromboxane (Tx)B2 release, produces pulmonary edema within 6 hours of intravenous infusion. This study tests the role of PMN in mediating the edema. Anesthetized rats received 10(6)U recombinant human IL-2 (n = 15) or vehicle (n = 14) as a constant intravenous infusion during a period of 1 hour. At this time there was leukopenia 3.63 +/- 0.43 (x10(3)/mm3) relative to vehicle-infused control rats 6.12 +/- 0.86 and a decline in PMN, 2.19 +/- 0.14 relative to control value of 3.33 +/- 0.05 (both p less than 0.05). After 6 hours edema, as measured by increase in the wet to dry weight (W/d) ratio, was present in the lungs (4.93 +/- 0.20 relative to control 4.06 +/- 0.10), heart (4.09 +/- 0.11 versus 3.76 +/- 0.08), liver (3.50 +/- 0.10 versus 3.18 +/- 0.10), and kidney (4.25 +/- 0.07 versus 4.00 +/- 0.07) (all p less than 0.05). There was increased lung permeability demonstrated by bronchoalveolar lavage fluid protein concentration of 1970 +/- 210 micrograms/mL relative to control 460 +/- 90 micrograms/mL (p less than 0.05). Interleukin-2 resulted in lung PMN sequestration of 53 +/- 7 PMN/10 high-power fields (HPF) relative to 23 +/- 2 PMN/10 HPF in controls (p less than 0.05) and increased plasma TxB2 levels to 1290 +/- 245 pg/mL relative to control 481 +/- 93 pg/mL (p less than 0.05). Pretreatment of other rats (n = 8) with selective anti-rat neutrophil antiserum 18 hours before the experiment led to a peripheral PMN count 10% of baseline and prevented edema in the lungs (W/d ratio 4.20 +/- 0.16) and heart (3.67 +/- 0.07) (both p less than 0.05) but not liver or kidney. Protein in lung lavage was reduced to 760 +/- 220 micrograms/mL (p less than 0.05). The protection afforded by leukopenia was associated with lack of PMN sequestration and prevention of the increase in plasma Tx levels (484 +/- 120 pg/mL, p less than 0.05). These data indicate that the rapid induction of lung and heart edema with a 1-hour infusion of IL-2 in the rat is mediated, in large part, by activated PMNs.

Role for tumor necrosis factor as mediator of lung injury following lower torso ischemia

Ischemia and reperfusion of the ischemic lower torso lead to a neutrophil- (PMN) dependent lung injury characterized by PMN sequestration and permeability edema. This mimics the injury seen after infusion of tumor necrosis factor alpha (TNF), a potent activator of PMN and endothelium. This study tests whether TNF is a mediator of the lung injury after lower torso ischemia. Anesthetized rats underwent 4 h of bilateral hindlimb tourniquet ischemia, followed by reperfusion for 10 min, 30 min, 1, 2, 3, and 4 h (n = 6 for each time point). Quantitative lung histology indicated progressive sequestration of PMN in the lungs, 25 +/- 3 (SE) PMN/10 high-power fields (HPF) 10 min after reperfusion vs. 20 +/- 2 PMN/10 HPF in sham animals (NS), increasing to 53 +/- 5 PMN/10 HPF after 4 h vs. 23 +/- 3 PMN/10 HPF in sham animals (P less than 0.01). There was lung permeability, shown by increasing protein accumulation in bronchoalveolar lavage (BAL) fluid, which 4 h after reperfusion was 599 +/- 91 vs. 214 +/- 35 micrograms/ml in sham animals (P less than 0.01). Similarly, there was edema, shown by the lung wet-to-dry weight ratio, which increased by 4 h to 4.70 +/- 0.12 vs. 4.02 +/- 0.17 in sham animals (P less than 0.01). There was generation of leukotriene B4 in BAL fluid (720 +/- 140 vs. 240 +/- 40 pg/ml, P less than 0.01), and in three of six rats tested at this time TNF was detected in plasma, with a mean value of 167 pg/ml. TNF was not detectable in any sham animal.(ABSTRACT TRUNCATED AT 250 WORDS)

Neutrophil accumulations due to pulmonary thromboxane synthesis mediate acid aspiration injury

Acid aspiration leads to lung injury associated with high levels of plasma thromboxane (Tx). This study tests the role of Tx synthesis by the aspirated lung segment in mediating local and remote neutrophil (PMN) sequestration, alveolar diapedesis, and permeability edema. Anesthetized rats underwent tracheostomy and insertion of a fine-bore cannula into the anterior segment of the left lung. This was followed by the installation of either 0.1 ml saline (n = 18) or the Tx synthase inhibitor OKY 046 (0.1 mg/kg in 0.1 ml, n = 18). Twenty minutes later either 0.1 ml 0.1 N HCL or 0.1 ml saline was similarly introduced (n = 18). Three hours later, in the saline-HCl group, the rise in Tx concentration in both plasma (1,340 pg/ml) and bronchoalveolar lavage (BAL) fluid (2,100 pg/ml) was higher than that in the saline-saline aspirated control group (350 and 115 pg/ml, respectively; both P less than 0.05). In the acid-aspirated lung PMN sequestration [87 PMN/10 high-power fields (HPF)] and diapedesis (96 x 10(4) PMN/ml in BAL) were higher than control values of 7 PMN/10 HPF and 3 x 10(4) PMN/ml (both P less than 0.05). Acid aspiration induced local permeability edema with a high protein concentration in BAL of 3,350 micrograms/ml and an increase in lung wet-to-dry weight ratio (W/D) of 6.6, both higher than control values of 482 micrograms/ml and 3.4, respectively (P less than 0.05). Leukosequestration in the aspirated side started at 30 min and was progressive over a 3-h monitoring period.(ABSTRACT TRUNCATED AT 250 WORDS)

Attenuation of IL-2-induced multisystem organ edema by phalloidin and antamanide

Interleukin 2 (IL-2) is a potent cytokine with diverse effects, including the ability to stimulate lymphocyte differentiation into cells capable of lysing tumor. Its therapeutic efficacy is limited because of side effects such as breakdown of the microvascular barrier and edema. Control of the microvascular barrier is in part regulated by endothelial cell cytoskeletal contractile proteins. This study tests whether the cyclopeptides that maintain actin filament organization and distribution and reduce macromolecular flux across the endothelial cell junction in vitro would similarly maintain barrier tightness and prevent early edema produced by IL-2 in vivo. Anesthetized rats were treated at 30-min periods with intravenous saline (0.5 ml, n = 41), phalloidin (20 micrograms in 0.5 ml, n = 21), or antamanide, (20 micrograms in 0.5 ml, n = 21), starting 30 min before the 1-h infusion of 10(6) U of recombinant human IL-2 or saline. Six hours after the start of IL-2, there was edema in the saline/IL-2 group, as measured by increased wet-to-dry ratios (W/D) in the lungs, heart, and kidney. With saline/IL-2, bronchoalveolar lavage (BAL) fluid contained an elevated protein concentration and higher plasma thromboxane levels compared with controls. The number of neutrophils sequestered in the lungs was more than twice that of saline controls. Phalloidin significantly attenuated edema in lung and reduced BAL protein leak. Antamanide treatment was as effective in limiting lung and heart edema, but, in contrast to phalloidin, antamanide prevented kidney edema and did not lead to an alteration in the liver W/D. Antamanide also prevented BAL fluid protein leak.(ABSTRACT TRUNCATED AT 250 WORDS)

Intravascular chemoattractants inhibit diapedesis by selective receptor occupancy

An extravascular chemoattractant leads to migration of polymorphonuclear neutrophils (PMN) to that site, whereas intravascular administration leads to PMN oxidative activity and sequestration in microvessels but no diapedesis. This study examines the inhibitory role of intravascular chemoattractants. Rabbits (n = 37) were pretreated with zymosan-activated plasma (ZAP), leukotriene (LT) B4, or thromboxane (Tx) mimic. These agents were given intra-arterially, topically into plastic chambers taped atop sites of dermabrasion on the back, or into a lobar bronchus (n = 35). Intra-arterial injection of each chemoattractant resulted, 10 min later, in a 29-42% increase in intracellular PMN H2O2. In saline-infused animals, topical administration of the chemoattractants into dermabrasion chambers resulted in PMN accumulation per cubic millimeter after 3 h of 600 with ZAP, 536 with LTB4, and 643 with Tx mimic; all values higher than 46 with saline and 63 with normal plasma (all P less than 0.05). In other saline-infused animals, lobar lung aspiration of chemoattractants led to diapedesis as measured in bronchoalveolar lavage (BAL) fluid (PMN x 10(4)/ml) after 3 h: 19.0 with ZAP, 11.2 with LTB4 and 14.5 with Tx mimic, all greater than aspiration with saline or normal plasma 4.0 and 4.9, respectively (all P less than 0.05). Intra-arterial chemotactic administration inhibited subsequent PMN diapedesis in response to that same chemoattractant, both in dermabrasion chambers and in BAL fluid. When different intra- and extra-vascular chemoattractants were used diapedesis was promoted. Thus Tx infused intra-arterially and ZAP applied to a blister or lobar bronchus led to rapid cell migration and increased cell numbers.(ABSTRACT TRUNCATED AT 250 WORDS)

Interleukin-2-induced lung injury is mediated by oxygen free radicals

Interleukin-2 therapy leads to respiratory dysfunction caused by increased vascular permeability. This study examines the role of oxygen-derived free radicals (OFR). Sheep (n = 6) with chronic lung lymph fistulae were given interleukin-2, 10(5) units/kg, as an intravenous bolus. The mean pulmonary artery pressure rose from 13 to 23 mm Hg (p less than 0.05) at 1 hour and remained elevated for 4 hours, although the pulmonary artery wedge pressure was unchanged at 4 mm Hg. Arterial oxygen tension fell from 88 to 77 mm Hg (p less than 0.05). Lung lymph flow rose from 2.2 to 6.4 ml/30 min (p less than 0.05) at 3 hours. This rise coincided with an increase in the lymph/plasma protein ratio from 0.67 to 0.77 (p less than 0.05) and lymph protein clearance from 1.5 to 4.4 ml/30 min (p less than 0.05), indicating increased lung microvascular permeability. Interleukin-2 led to transient increases in plasma thromboxane B2 from 168 to 388 pg/ml (p less than 0.05) and lung lymph thromboxane B2 from 235 to 694 pg/ml (p less than 0.05). The leukocyte count fell from 8156 to 4375/mm3 (p less than 0.05) primarily caused by a 78% drop in lymphocyte count. Platelet count declined from 292 to 184 X 10(3)/mm3 (p less than 0.05). Pretreatment with the hydroxyl radical scavenger dimethylthiourea, 1 gm/kg, intravenously, (n = 6) prevented the interleukin-2-induced increase in mean pulmonary artery pressure, lung lymph flow, lymph/plasma protein ration, lymph protein clearance, and thromboxane B2 levels in plasma and lung lymph. The arterial oxygen tension decreased from 85 to 80 mm Hg (p less than 0.05). The leukocyte count declined from 7854 to 6229/mm3 (p less than 0.05), but this was not as low nor as prolonged as the interleukin-2 group. Further, the decrease in platelet count was prevented (p less than 0.05). Interleukin-2 incubated with sheep or human leukocytes led to a dose-dependent increase in intracellular hydrogen peroxide production by neutrophils as measured by flow cytometry of dichlorofluorescein oxidation. These data indicate that interleukin-2 stimulates OFR generation and that OFR moderate the interleukin-2-induced increased lung permeability.

Involvement of thromboxane and neutrophils in multiple-system organ edema with interleukin-2

Interleukin-2 (IL-2) produces toxicity characterized by generalized edema within 24 hours. This study tests whether the rate of IL-2 administration modulates the onset of edema and examines thromboxane (Tx) and neutrophils as possible mediators of this event. Recombinant human IL-2, 10(5) U (n = 7), 10(6) U (n = 9), or vehicle (n = 8) were given to anesthetized rats intravenously during a period of 1 hour. At 6 hours edema, as measured by increase in wet to dry weight (w/d) ratio, was present in the heart, liver, and kidney, with 10(5) U IL-2 and in the lung, heart, liver and kidney, with 10(6) U IL-2, relative to values with vehicle-infused controls (all p less than 0.05). With a 1-hour infusion of 10(6) U IL-2, there was an increase in plasma thromboxane (Tx)B2 level to 1290 +/- 245 pg/mL, higher than 481 +/- 93 pg/mL in control rats (p less than 0.05); lung polymorphonuclear leukocyte (PMN) sequestration of 53 +/- 7 PMN/10 higher-power fields (HPF) relative to 23 +/- 2 PMN/10 HPF in controls (p less than 0.05); and increased bronchoalveolar lavage (BAL) fluid protein concentration of 1970 +/- 210 micrograms/mL relative to 460 micrograms/mL in controls (p less than 0.05). When 10(6) U IL-2 was given as a 1-minute intravenous bolus (n = 9), edema was not demonstrated, plasma TxB2 levels were similar to controls, there was no leukosequestration, and BAL protein levels were normal. These data indicate that a constant infusion but not the rapid bolus administration of IL-2 produces in rats multiple-system organ edema, increased plasma TxB2, sequestration of PMNs, and microvascular permeability. These findings may explain the early toxicity seen in patients given high-dose IL-2 in cancer treatment.

Attenuation of acid aspiration edema with phalloidin

Acid aspiration leads to pulmonary endothelial and epithelial cell (EC/EpC) injury characterized by increased permeability and polymorphonuclear (PMN) leukocyte diapedesis. Actin in the EC/EpC cytoskeleton has been shown to play a significant role in maintenance of the microvascular junction barrier. This study tests indirectly whether the development of permeability and diapedesis following acid aspiration is via disruption of the pulmonary cytoskeleton. Manipulation was achieved by the actin microfilament assembler phalloidin. Anesthetized rats (n = 88) underwent segmental lung installation of 0.1 ml saline or phalloidin (2 x 10(-6) M). Twenty minutes later 0.1 N HCl, saline, or phalloidin was introduced. After 3 h there was an increase in wet-to-dry weight (W/D) ratio of 6.6 and 5.1 in the HCl-injected and noninjected sides, protein concentration, 3,970 and 2,530 micrograms/ml, and accumulation of 93 PMN/ml (x 10(4] in bronchoalveolar lavage (BAL) of the HCl-injected lung. These values were higher than control animals. Local pretreatment with phalloidin attenuated acid-induced localized but not generalized permeability with reduction in W/D ratio, BAL protein concentration, and diapedesis (P less than 0.05). Acid injection into airways also led to elevated thromboxane B2 and leukotriene B4 levels in plasma and BAL (P less than 0.05) and generalized lung leukosequestration, events not affected by phalloidin. Taken together, these data suggest that acid aspiration lung injury is determined largely by loss of integrity of the pulmonary EC/EpC cytoskeleton with resultant loss of barrier function.

Tumor necrosis factor-alpha mediates acid aspiration-induced systemic organ injury

Acid aspiration-induced systemic organ injury is mediated by the sequestration of activated neutrophils (PMN). In other settings cytokines have been shown to increase neutrophil-endothelial adhesion, a requisite for injury. This study tests whether the systemic leukosequestration and permeability following localized aspiration is mediated by tumor necrosis factor (TNF)-alpha-induced synthesis of an adhesion protein. Anesthetized rats underwent tracheostomy and insertion of a fine-bore cannula into the anterior segment of the left lung. This was followed by the instillation of either 0.1 mL 0.1 N HCI (n = 18) or 0.1 mL saline in control rats (n = 18). Localized aspiration induced generalized pulmonary leukosequestration with 95 PMN/10 high-power fields (HPF) in the aspirated lung and 46 PMN/10 HPF in the nonaspirated lung, higher than control values of 7 PMN/10 HPF and 5 PMN/10 HPF in saline- and nonsaline-aspirated sides, respectively (p less than 0.05). The leukosequestration was associated with permeability edema shown by increased protein concentrations in bronchoalveolar lavage (BAL) of 3900 micrograms/mL in the aspirated and 2680 micrograms/mL in the nonaspirated side, higher than saline with 482 micrograms/mL and 411 micrograms/mL, respectively (p less than 0.05). There was generalized pulmonary edema following aspiration measured by increase in wet-to-dry weight ratios (w/d) of 6.6 in the aspirated and 5.1 in the nonaspirated lung, higher than control values of 3.5 and 3.4, respectively (p less than 0.05). Localized aspiration led to systemic leukosequestration documented by increases in myeloperoxidase activity (units/g tissue) of 2.2 and 1.7 in heart and kidney, higher than control values of 0.3 and 0.4, respectively (p less than 0.05). This event was associated with edema of these organs with w/d ratios of 4.6 and 4.3, relative to control values of 3.0 and 3.4 (p less than 0.05). Treatment of animals (n = 18) 20 minutes after aspiration with anti-TNF-alpha antiserum (rabbit anti-murine) but not normal rabbit serum (n = 18) reduced lung leukosequestration in the aspirated and nonaspirated segments (61 and 32 PMN/10HPF), BAL protein concentration (1490 and 840 micrograms/mL), and w/d ratio (4.3 and 3.7) (all p less than 0.05). In the heart and kidney there were reductions in myeloperoxidase activity (0.7 and 0.6) and w/d ratio (3.5 and 3.6) (both p less than 0.05). Treatment of rabbits (n = 18) with the protein synthesis inhibitor cycloheximide, 0.2 mg/kg/hr was as effective as TNF-alpha antiserum in modifying aspiration injury.(ABSTRACT TRUNCATED AT 400 WORDS)

Neutrophil adherence receptors (CD 18) in ischemia. Dissociation between quantitative cell surface expression and diapedesis mediated by leukotriene B4

Neutrophils and eicosanoid chemoattractants are centrally involved with ischemia-reperfusion (I/R) injury. The CD 18 complex of adhesive glycoproteins, readily up-regulated by chemoattractants in vitro, is required for polymorphonuclear leukocyte (PMN) adherence to endothelium. This study tests whether CD 18 is up-regulated by ischemia in vivo and its role in mediating PMN diapedesis. Anesthetized rabbits underwent 3 h of bilateral hindlimb tourniquet ischemia (n = 16). Ten min after tourniquet release, levels of plasma leukotriene (LT)B4 increased to 390 +/- 62 pg/ml (mean +/- SE), higher than 134 +/- 26 pg/ml in control rabbits (n = 13, p less than 0.01). Aliquots of plasma were added to whole blood from normal rabbits (n = 6) for flow cytometric analysis of neutrophils with the CD 18 mAb R 15.7. Addition of I/R plasma failed to demonstrate an increase in surface expression of CD 18. Similarly, no CD 18 up-regulation was observed in vivo upon reperfusion in ischemic animals pretreated with mAb R 15.7 (n = 3). However, I/R plasma when introduced into plastic chambers taped atop dermabrasion sites in normal rabbits (n = 12) resulted in diapedesis, measured by the accumulation after 3 h of 1130 +/- 125 PMN/mm3 in the chambers relative to 120 +/- 31 PMN/mm3 with control plasma (p less than 0.01). Diapedesis in response to I/R plasma was abolished by pretreatment with mAb R 15.7 (less than 5 PMN/mm3, n = 6), was reduced by U 75,302, an LTB4 receptor antagonist (253 +/- 101 PMN/mm3, n = 6) (both p less than 0.01) and was not protein synthesis dependent. These results demonstrate that PMN diapedesis in response to I/R plasma is exclusively dependent upon the CD 18 glycoprotein complex by an LTB4-dependent mechanism, despite the fact that CD 18 is not up-regulated on circulating PMN in ischemia. These data indirectly indicate the functional importance of conformational changes of CD 18 in determining PMN adhesion.

Neutrophil adherence receptors (CD 18) in ischemia. Dissociation between quantitative cell surface expression and diapedesis mediated by leukotriene B4

Neutrophils and eicosanoid chemoattractants are centrally involved with ischemia-reperfusion (I/R) injury. The CD 18 complex of adhesive glycoproteins, readily up-regulated by chemoattractants in vitro, is required for polymorphonuclear leukocyte (PMN) adherence to endothelium. This study tests whether CD 18 is up-regulated by ischemia in vivo and its role in mediating PMN diapedesis. Anesthetized rabbits underwent 3 h of bilateral hindlimb tourniquet ischemia (n = 16). Ten min after tourniquet release, levels of plasma leukotriene (LT)B4 increased to 390 +/- 62 pg/ml (mean +/- SE), higher than 134 +/- 26 pg/ml in control rabbits (n = 13, p less than 0.01). Aliquots of plasma were added to whole blood from normal rabbits (n = 6) for flow cytometric analysis of neutrophils with the CD 18 mAb R 15.7. Addition of I/R plasma failed to demonstrate an increase in surface expression of CD 18. Similarly, no CD 18 up-regulation was observed in vivo upon reperfusion in ischemic animals pretreated with mAb R 15.7 (n = 3). However, I/R plasma when introduced into plastic chambers taped atop dermabrasion sites in normal rabbits (n = 12) resulted in diapedesis, measured by the accumulation after 3 h of 1130 +/- 125 PMN/mm3 in the chambers relative to 120 +/- 31 PMN/mm3 with control plasma (p less than 0.01). Diapedesis in response to I/R plasma was abolished by pretreatment with mAb R 15.7 (less than 5 PMN/mm3, n = 6), was reduced by U 75,302, an LTB4 receptor antagonist (253 +/- 101 PMN/mm3, n = 6) (both p less than 0.01) and was not protein synthesis dependent. These results demonstrate that PMN diapedesis in response to I/R plasma is exclusively dependent upon the CD 18 glycoprotein complex by an LTB4-dependent mechanism, despite the fact that CD 18 is not up-regulated on circulating PMN in ischemia. These data indirectly indicate the functional importance of conformational changes of CD 18 in determining PMN adhesion.

Selective down-regulation of alveolar macrophage oxidative response to opsonin-independent phagocytosis

We have compared the oxidative response of alveolar macrophages (AM) during opsonin-dependent and independent phagocytosis by using multiparameter flow cytometry. The respiratory burst of AM during phagocytosis was quantitated by the intracellular oxidation of the nonfluorescent precursors dichlorofluorescin diacetate (DCFH) or hydroethidine (HE, a reduced precursor of ethidium) to their fluorescent (oxidized) counterparts. After loading freshly isolated normal hamster AM with DCFH or HE, red or green fluorescent beads, respectively, were added to the shaking cell suspensions. Ingestion of opsonized particles by AM caused a marked increase in oxidation of both DCFH and HE proportional to the number of beads ingested. In contrast, uptake of one to three unopsonized particles per cell led to inhibition of oxidative activity compared to control cells incubated without particles. AM ingesting four or more unopsonized particles showed some increase in oxidative metabolism, but far less than that with identical numbers of particles in opsonin-dependent ingestion. Similar results were obtained using fluorescent labeled staphylococcal bacteria. Using three-color flow cytometry to study cells ingesting both types of particles, cells first ingesting unopsonized beads were also found to have an inhibited oxidative response to subsequently ingested opsonized particles. The mitochondrial poison antimycin inhibited most of the intracellular oxidative response to either type of phagocytosis. The remaining antimycin-insensitive, membrane derived respiratory burst of AM was also substantially diminished after phagocytosis of unopsonized particles vs similar numbers of opsonized particles. The greatly increased mitochondrial respiration in AM during phagocytosis of opsonized particles may be related to bactericidal mechanisms. Killing of ingested Staphylococcus by AM was markedly impaired in the presence of antimycin. The results suggest that AM may ingest the numerous, unopsonized inert particles that are inhaled without generation of potentially toxic oxygen metabolites, while retaining the capacity to undergo a respiratory burst after ingesting opsonized particles and bacteria. The mechanism(s) for this distinct response may include generation of an inhibitor of intracellular oxidative metabolism.

Selective down-regulation of alveolar macrophage oxidative response to opsonin-independent phagocytosis

We have compared the oxidative response of alveolar macrophages (AM) during opsonin-dependent and independent phagocytosis by using multiparameter flow cytometry. The respiratory burst of AM during phagocytosis was quantitated by the intracellular oxidation of the nonfluorescent precursors dichlorofluorescin diacetate (DCFH) or hydroethidine (HE, a reduced precursor of ethidium) to their fluorescent (oxidized) counterparts. After loading freshly isolated normal hamster AM with DCFH or HE, red or green fluorescent beads, respectively, were added to the shaking cell suspensions. Ingestion of opsonized particles by AM caused a marked increase in oxidation of both DCFH and HE proportional to the number of beads ingested. In contrast, uptake of one to three unopsonized particles per cell led to inhibition of oxidative activity compared to control cells incubated without particles. AM ingesting four or more unopsonized particles showed some increase in oxidative metabolism, but far less than that with identical numbers of particles in opsonin-dependent ingestion. Similar results were obtained using fluorescent labeled staphylococcal bacteria. Using three-color flow cytometry to study cells ingesting both types of particles, cells first ingesting unopsonized beads were also found to have an inhibited oxidative response to subsequently ingested opsonized particles. The mitochondrial poison antimycin inhibited most of the intracellular oxidative response to either type of phagocytosis. The remaining antimycin-insensitive, membrane derived respiratory burst of AM was also substantially diminished after phagocytosis of unopsonized particles vs similar numbers of opsonized particles. The greatly increased mitochondrial respiration in AM during phagocytosis of opsonized particles may be related to bactericidal mechanisms. Killing of ingested Staphylococcus by AM was markedly impaired in the presence of antimycin. The results suggest that AM may ingest the numerous, unopsonized inert particles that are inhaled without generation of potentially toxic oxygen metabolites, while retaining the capacity to undergo a respiratory burst after ingesting opsonized particles and bacteria. The mechanism(s) for this distinct response may include generation of an inhibitor of intracellular oxidative metabolism.

Benign pulmonary lesions that may be misdiagnosed as malignant

Five benign pulmonary lesions that may be misdiagnosed as malignant tumors are reviewed. In three lesions, diagnostic problems arise when a spindle cell component is dominant and obscures other characteristic histologic features. In the inflammatory pseudotumor, correct diagnosis relies on recognition of the benign cytology of the spindle cells and identifying a typical admixture of plasma cell-rich inflammatory cells. For spindle cell carcinoids, useful diagnostic features are the organoid pattern, benign cytology, and neuroendocrine differentiation features of the spindle cells. Localized pleural mesothelioma (fibroma) is composed of benign spindle cells in a fibrocollagenous background; mesothelial differentiation is not present by ultrastructural or immunocytochemical analysis. In sclerosing hemangioma, a complex histology may suggest a number of malignancies. Observation of solid and papillary areas of benign tumor cells, as well as sclerosis of vessel walls and intervening areas, will allow correct diagnosis. Pseudolymphoma, a nodular benign lymphoid infiltrate, is distinguished by its polymorphous and polyclonal composition and numerous germinal centers.

Oxidative metabolism in the alveolar macrophage: analysis by flow cytometry

We evaluated the reagents dichlorofluorescin (DCFH) and hydroethidine (HE) for use in flow cytometric analysis of the respiratory burst of alveolar macrophages and monocytes. DCFH and HE are non-fluorescent precursors which can be oxidized intracellularly to the fluorescent compounds dichlorofluorescein and ethidium. Alveolar macrophages (AMs) loaded with either DCFH or HE were analyzed after phorbol myristate acetate (PMA) stimulation. The results, expressed as fmol/cell oxidation product (DCF or ethidium) after fluorometric standardization of the flow cytometer, show that both DCFH (273 +/- 48, mean increase over control +/- SE, fmol/cell, N = 9) and HE (416 +/- 54, N = 11) detected the substantial respiratory burst of hamster AMs. Similar results were obtained with normal human AMs. By using multiparameter analyses, the oxidative response of AMs ingesting opsonized fluorescent latex beads was measured in subpopulations ingesting increasing numbers of particles. A graded increase in oxidation of both DCFH and HE was found in response to increasing phagocytosis. Ingestion of fluoresceinated staphylyococcal bacteria caused similar changes in HE-loaded AMs. Inhibition of respiration with antimycin showed that approximately 95% of the increased oxidative metabolism of hamster AMs ingesting opsonized beads or bacteria was mitochondrial. The remaining 5% (10-40 fmol/cell) is membrane-derived oxidative activity quantitatively similar to that measured in assays of extracellular release of H2O2. Monocytes loaded with either DCFH or HE showed substantial increases in fluorescence after PMA stimulation (mean % increase over control +/- SE at 30 min: 464 +/- 104, DCFH, 505 +/- 156, HE). While DCHF is known to measure H2O2, HE is less well characterized. Exposure of cells to an extracellular source of both superoxide anion (O2-) and H2O2, xanthine oxidase-xanthine, resulted in marked oxidation of intracellular HE. Addition of both superoxide dismutase and catalase blocked this oxidation, indicating that HE can detect both O2- and H2O2. These agents can be useful probes for precise analysis of oxidative metabolism during phagocytosis in AMs and other mononuclear phagocytes.

Ischemia-induced neutrophil activation and diapedesis is lipoxygenase dependent

Ischemia and reperfusion lead to eicosanoid- and neutrophil (PMN)-dependent injury. This study tests the role of ischemia-induced lipoxygenase activity in mediating PMN activation and diapedesis. Anesthetized rabbits (n = 8) underwent 3 hours of bilateral hindlimb ischemia. At 10 minutes of reperfusion, leukotriene B4 (LTB4) levels in femoral venous effluent were 0.49 +/- 0.05 ng/ml compared with 0.04 +/- 0.07 ng/ml in sham-treated animals (n = 10) (p less than 0.05). Intracellular H2O2 production of circulating PMNs assayed flow cytometrically by dichlorofluorescein (DCF) oxidation, increased from a preischemic value of 74 +/- 14 femtomoles DCF/cell to 135 +/- 8 fmol DCF/cell (p less than 0.05). PMNs were treated with phorbol myristate acetate (PMA), 10(-7) mol/L. In contrast to a 162% increase in H2O2 production before ischemia, PMNs at 10 minutes of reperfusion had an enhanced response to PMA of 336% (p less than 0.05). Addition of authentic LTB4 (0.5 ng/ml) to PMN from sham-treated animals led to their activation, manifest by an oxidative burst, 127 +/- 12 fmol DCF/cell, and an enhanced response of 337% to PMA stimulation. To study diapedesis, plasma collected at 10 minutes of reperfusion was introduced into plastic chambers taped atop skin abrasions in rabbits (n = 8). After 3 hours, 1610 +/- 246 PMN/mm3 accumulated and LTB4 levels in blister fluid were 0.83 +/- 0.03 ng/ml, higher than values of 44 +/- 23 PMN/mm3 (p less than 0.05) and 0.04 +/- 0.03 ng LTB4/ml (p less than 0.05) with saline solution and 68 +/- 16 PMN/mm3 (p less than 0.05) and 0.19 +/- 0.02 ng/ml (p less than 0.05) with nonischemic plasma. The introduction of LTB4, 3.3 ng/ml, into the chambers resulted in an accumulation of 536 +/- 352 PMN/mm3 (p less than 0.05). Pretreatment of animals before hindlimb ischemia (n = 5) with the lipoxygenase inhibitor diethylcarbamazine abolished PMN activation (51 +/- 12 fmol DCF/cell) and ischemic plasma-induced diapedesis into the plastic chamber (38 +/- 18 PMN/mm3). Pretreatment of nonischemic animals (n = 13) used for the dermabrasion bioassay with diethylcarbamazine abolished diapedesis into the plastic chambers induced by ischemic plasma (n = 5) (32 +/- 24 PMN/mm3) or LTB4 (n = 3) (36 +/- 28 PMN/mm3). These data indicate that PMN activation after reperfusion of ischemic tissue is mediated by a lipoxygenase product, perhaps LTB4, and that both reperfusion plasma and authentic LTB4 induce diapedesis by stimulating de novo lipoxygenase activity.