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Divisions of
*
Pulmonary Biology and
Critical Care Medicine, Children’s Hospital Medical Center, Cincinnati, OH 45229;
Department of Medicine and Pathology, Boston University School of Medicine, Boston, MA 02118; and
Department of Pathology, Washington University School of Medicine, St. Louis, MO 63110
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Abstract |
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 Top Abstract IntroductionMaterials and MethodsResultsDiscussionReferences |
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Introduction |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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In the lung, SP-D is produced primarily by alveolar type II cells, tracheobronchial glands, and nonciliated bronchiolar cells (4). In vitro, SP-D interacts with bacteria, fungi, and viruses. SP-D binds to alveolar macrophages (5) and binds and increases macrophage association with Escherichia coli (6), Pseudomonas aeruginosa (7), Mycobacterium tuberculosis (8), and Pneumocystis carinii (9). In vitro, mannose binding protein, conglutinin, SP-A, and SP-D neutralize influenza A virus (IAV) and enhance the association of neutrophils with IAV (10, 11, 12, 13, 14).
IAV infection is airborne and is primarily an infection of the upper respiratory tract. However, during infection virus spreads to the lower respiratory tract and may result in viral pneumonia or predispose to secondary bacterial infections. Influenza infections are most frequent in children and young adults, yet deaths are most frequent in the very young (<1 yr), the elderly, and persons of all ages with underlying heart or lung disease (15). Bronchopulmonary dysplasia has been associated with decreased secretion of SP-D (16), and cystic fibrosis has been associated with decreased SP-D concentrations in pulmonary washes (17), conditions that may increase susceptibility to infection by respiratory viruses such as IAV.
Specific as well as nonspecific immune mechanisms take part in the host response to influenza virus. IAV infection is a lytic infection and causes breakdown of the blood-tissue barrier early in infection, resulting in the influx of macrophages, neutrophils, and NK cells into the lung. Specific immune responses to IAV are initiated by the influx of virus-specific T lymphocytes and Ab production, and CTL are thought to be involved in viral clearance by direct cytolysis of virus-infected cells (18). Neutrophils also play an important role in viral clearance from the lung. Mice irradiated to reduce the number of peripheral polymorphonuclear leukocytes have increased viral titers after influenza infection of in the lung (19). Defects in neutrophil and monocyte chemotactic, oxidative, and bacterial killing functions have been documented in IAV infection (20, 21). In vitro, neutrophil dysfunction resulting from IAV exposure is diminished when the virus is preincubated with SP-D (14). On the other hand, SP-D has been reported to have no effect on IAV uptake by alveolar macrophages (22).
Although there is compelling evidence that SP-D enhances host defense against viruses in vitro, its role in the clearance of viral pathogens in vivo has not been demonstrated. In the present study SP-D-deficient mice were infected intranasally with SP-D-sensitive and -resistant strains of IAV. Rescue experiments were performed using highly purified recombinant SP-D. IAV clearance, lung inflammation, cytokine production, and uptake of virus by macrophages and neutrophil activity were compared in SP-D-/- and SP-D+/+ mice in vivo.
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Materials and Methods |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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SP-D-/- mice were produced by targeted gene inactivation (23). Lungs of SP-D-/- mice do not contain detectable SP-D. National Institutes of Health Swiss Black SP-D+/+ and SP-D-/- mice were studied. Mice were housed in barrier containment and remained virus free as assessed by serology. Studies were reviewed and approved by the institutional animal care and use committee of the Children’s Hospital Research Foundation (Cincinnati, OH). Male and female mice of approximately 20–25 g (35–42 days old) were used.
Preparation of IAV
IAV strain H3N2 A/Phillipines/82 (Phil/82) and H3N1 Mem71H-BelN (Mem71) were gifts from E. M. Anders to K. Hartshorn (University of Melbourne, Melbourne, Australia) and were grown in the chorioallantoic fluid of 10-day-old embryonated hen’s eggs. Allantoic fluid was harvested after 48 h of incubation and was clarified by centrifugation at 1,000 x g for 40 min, followed by centrifugation at 135,000 x g to precipitate viruses. The virus-containing pellets were resuspended and purified on a discontinuous sucrose density gradient as previously described (24). Virus stocks were dialyzed against PBS, separated into aliquots, and stored at -70°C until used.
The potency of each viral stock was measured by the fluorescent foci assay (24) after samples were thawed from frozen storage at -70°C. Several stocks were used which varied from 5 x 108 to 5 x 109 fluorescent foci/ml.
FITC labeling of IAV
FITC stock was prepared at 1 mg/ml in 1 mol/L sodium carbonate, pH 9.6. FITC-labeled virus (Phil/82) was prepared by incubating concentrated virus stocks with FITC (10/1 mixture (v/v) of virus in PBS with FITC stock) for 1 h, followed by dialysis of the mixture for 18 h against PBS.
Viral clearance of influenza
Mice were lightly anesthetized with isoflurane and inoculated intranasally with 105 fluorescent foci (ff) of IAV in 50 µl PBS. Quantitative IAV cultures of lung homogenates were performed 3, 5, 7, and 10 days after inoculation of the animals with IAV. The entire lung was removed, homogenized in 2 ml sterile PBS, quick-frozen, weighed, and stored at -80°C. Madin-Darby canine kidney cell monolayers were prepared in 96-well plates for the viral focus assay as previously described (24). The layers were incubated with lung homogenates diluted in PBS containing 2 mM calcium for 45 min at 37°C, and the monolayers washed three times in virus-free DMEM containing 1% penicillin and streptomycin. The monolayers were incubated for 7 h at 37°C in DMEM and repeatedly washed, and the cells were fixed with 80% (v/v) acetone for 10 min at -20°C. The monolayers were then incubated with mAb directed against IAV nucleoprotein (mAb A-3) and then with rhodamine-labeled goat anti-mouse IgG. Fluorescent foci were counted directly under fluorescent microscopy. The resulting titer was divided by the lung weight and reported as ff per gram of lung.
Treatment with human SP-D
Human SP-D was isolated as previously described (25). Briefly, CHO-K1 cells (ATCC CCL-61; American Type Culture Collection, Manassas, VA) were transfected with a full-length human cDNA in the pEE14 mammalian expression vector. Secreted SP-D was isolated by maltosyl-agarose affinity chromatography, and SP-D dodecamers were resolved from larger multimers and trimers by gel filtration chromatography under nondenaturing conditions. Proteins were concentrated by rechromatography on maltosyl-agarose. Bound proteins were eluted in HEPES-buffered saline containing 10 mM EDTA and stored at -80°C. The protein concentration was estimated using a dye binding assay with BSA as standard. The level of endotoxin contamination was quantified using an end-point chromogenic microplate assay (Chromogenix, Molndal, Sweden) with E. coli 0111:B4 endotoxin as a standard. The endotoxin content of the purified recombinant proteins used for these experiments was <2 ng/ml for stock solutions. Quantitative IAV cultures of lung homogenates were performed 3 days after intranasal inoculation of mice with IAV, followed by intratracheal inoculation with PBS or SP-D (5 µg).
Bronchoalveolar lavage (BAL)
Lung cells were recovered by BAL. Animals were sacrificed as described for viral clearance, and lungs were lavaged three times with 1 ml sterile PBS. The fluid was centrifuged at 2000 rpm for 10 min and resuspended in 600 µl PBS, and total cells were stained with trypan blue and counted under light microscopy. Differential cell counts were performed on cytospin preparations stained with Diff-Quick (Dade Behring, Newark, DE).
Cytokine production
Lung homogenates were centrifuged at 2000 rpm, and the
supernatants were stored at -20°C. TNF-
, IL-1
, IL-6, and
macrophage inflammatory protein 2 (MIP-2) were quantitated using murine
sandwich ELISA kits (R&D Systems, Minneapolis, MN) according to the
manufacturer’s directions. All plates were read on a microplate reader
(Molecular Devices, Menlo Park, CA) and analyzed with the use of a
computer-assisted analysis program (Softmax, Molecular Devices). Only
assays having standard curves with a calculated regression line value
>0.95 were accepted for analysis.
Phagocytosis of IAV
Phagocytosis of IAV by macrophages in vivo was measured by intranasally infecting mice with FITC-labeled IAV, followed by evaluation of cell-associated fluorescence with a flow cytometer. Two hours after infection, macrophages from BAL fluid (BALF) were incubated in buffer (PBS, 0.2% BSA fraction V, and 0.02% sodium azide) with PE-conjugated murine CD16/CD32 Abs (BD PharMingen, San Diego, CA) for 1 h on ice and washed twice in fresh buffer. Trypan blue (0.2 mg/ml) was added to quench fluorescence of extracellular FITC. Cell-associated fluorescence was measured on a FACScan flow cytometer using CellQuest software (BD Biosciences, San Jose, CA). For each sample of macrophages, 20,000 cells were counted in duplicate, and the results are expressed as the percentage of macrophage phagocytosis.
CD4 and CD8 T lymphocytes in BALF
CD4 and CD8 T lymphocytes were measured after intranasal IAV infection and staining of cells in BALF with fluorescent Abs, followed by evaluation of cell-associated fluorescence by flow cytometry. Three days after infection, cells from BALF were incubated in buffer (PBS, 0.2% BSA fraction V, 0.02% sodium azide) with rat anti-mouse CD16/CD32 Abs (Fc Block), FITC-conjugated mouse CD4, and PE-conjugated mouse CD8 Abs (BD PharMingen) for 1 h on ice and washed twice in fresh buffer. Cell-associated fluorescence was measured on a FACScan flow cytometer using CellQuest software (BD Biosciences). For each sample 20,000 cells were counted, and the results are expressed as the percentage of CD4 and CD8 T lymphocytes in BALF.
Neutrophil myeloperoxidase (MPO) activity
MPO activity was measured in BAL neutrophils and whole lung 3 days after intranasal infection with IAV at a concentration of 106 ff. A higher concentration of virus was used to provide adequate neutrophils to study. BALF from three wild-type mice was pooled to provide sufficient neutrophils, whereas a single SP-D-/- mouse was used. Blood obtained from uninfected SP-D+/+ mice was separated on a gradient of neutrophil isolation medium (NIM-1, Cardinal Associates, Santa Fe, NM) to isolate blood neutrophils. Neutrophils were added to homogenate buffer (100 mM sodium acetate (pH 6.0), 20 mM EDTA (pH 7.0), 1% hexadecyl trimethylammonium bromide) in a 96-well microtiter plate in a final volume of 50 µl. The neutrophil mixtures were incubated at 37°C for 1 h to lyse the neutrophils and allow release of MPO from the granules. Assay buffer (100 µl) containing 1 mM H2O2, 1% homogenate buffer (see above), and 3.2 mM 3,3'5,5'-tetramethylbenzidine was added to each well, and readings were taken at 650 nm using a Thermomax microplate reader (Molecular Devices) for a period of 4 min. Lungs were harvested, weighed, and homogenized in 3 ml homogenate buffer, sonicated for 15 s, then centrifuged at 10,000 x g for 15 min at 4°C. The supernatants were diluted 1/15 in the homogenate buffer, mixed with an equal volume of assay buffer, and read at 650 nm over 4 min. Readings were the average of at least three individual wells, and MPO activity was reported as maximum MPO activity per 4 min per 3 x 103 neutrophils or MPO activity per gram of lung for isolated neutrophils or whole lung, respectively.
SP-D concentrations
Concentrations of SP-D in lung homogenates were determined by ELISA. Three and 5 days after infection with IAV, lungs from infected and uninfected wild-type mice were removed and homogenized in 2 ml PBS. SP-D concentrations were measured in a double-Ab ELISA using rabbit and guinea pig anti-SP-D sera. Each assay plate included a standard curve generated with purified mouse SP-D. All samples were run in duplicate, and the concentrations of the samples were calculated by graphing absorbance vs concentrations of the standard.
Statistical methods
Lung viral titers, total cell counts, cytokines, MPO activity, and SP-D levels were compared using ANOVA and Student’s t test. Findings were considered statistically significant at p < 0.05.
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Results |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Intranasal administration of IAV (105 ff)
was well tolerated. Mice infected with IAV lost weight during the 4
days after infection. The percentage of weight loss was greater for the
SP-D-/- mice with 14.4 ± 1.4% compared
with 1.5 ± 1.0% for the SP-D+/+ mice
(mean ± SEM; n = 6 mice; p <
0.05 compared with SP-D+/+ mice). Increased
total cell counts in BALF were observed in
SP-D-/- mice 3 and 5 days after IAV infection
(Fig. 1
). Baseline total cell counts in
BAL fluid from controls inoculated with PBS (days 3 and 5) or
uninfected controls were not significantly different for the
SP-D+/+ and SP-D-/- mice
(Fig. 1). A significantly greater percentage of polymorphonuclear
leukocytes was detected in BAL fluid from
SP-D-/- compared with
SP-D+/+ mice 3 and 5 days postinfection
(Fig. 1).
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Quantitative IAV cultures of lung homogenates were performed 3, 5,
7, and 10 days after inoculation of the animals with IAV. Increased
viral titers of IAV (Phillipines/82) were observed in the lungs of
SP-D-/- mice 3, 5, 7, and 10 days after
infection compared with SP-D+/+ mice (Fig. 2). Intratracheal coadministration of
recombinant SP-D (5 µg) enhanced clearance of A/Phillipines/82
(H3N2) (Phil/82) virus from
the lung of SP-D-/- compared with untreated
SP-D-/- mice (Fig. 2).
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Cytokine levels in lung homogenates
Three and 5 days after IAV infection, proinflammatory cytokines
TNF-, IL-1, and IL-6 were significantly increased in lung
homogenates from SP-D-/- compared with
SP-D+/+ mice (Fig. 3). IFN-
was increased in
the lungs of SP-D-/- mice compared with
SP-D+/+ mice after IAV infection. Lungs from the
SP-D-/- mice had the greatest concentration of
IFN- 5 days after IAV infection with 91 ± 20 and 2398 ±
176 pg/ml for SP-D+/+ and
SP-D-/- mice, respectively (mean ± SEM;
p < 0.05). MIP-2, a neutrophil chemoattractant, was
significantly greater in lung homogenates from
SP-D-/- mice after viral infection (Fig. 3). Intratracheal treatment with SP-D
significantly reduced TNF- and IL-6 levels in the lung (Fig. 3).
Basal cytokine levels in the lungs of control mice inoculated with
sterile PBS were low or absent and were not different in
SP-D-/- and SP-D+/+ mice
(data not shown).
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Phagocytosis of FITC-labeled IAV by alveolar macrophages was assessed by flow cytometry. Uptake of virus was similar in SP-D+/+ and SP-D-/- mice (11.1 ± 1.9 and 9.4± 1.9% phagocytosis, respectively) 2 h after IAV infection (mean ± SEM). These results suggest that macrophage phagocytosis of IAV is not a major contributor to the decreased clearance of IAV seen in the absence of SP-D in vivo.
CD4 and CD8 T lymphocytes in BALF
Three days after IAV infection, CD4 (Th lymphocytes) and CD8 (CTL)
cells were measured in BALF. There was no difference in the percentages
of CD4 and CD8 T lymphocytes in BALF between
SP-D-/- and SP-D+/+ mice
(Fig. 4). The fractions of CD4 and CD8 T lymphocytes in BALF were
similar in uninfected SP-D+/+ and
SP-D-/- mice (Fig. 4).
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MPO is stored in specific granules of neutrophils. Neutrophil
accumulation in the lung was quantitated by measuring MPO activity in
lung homogenates, and neutrophil function was assessed by measuring
levels of MPO associated with neutrophils recovered in lung lavage.
Although MPO activity was greater in the lungs of
SP-D-/- mice after IAV infection, MPO activity
from isolated BAL neutrophils was significantly decreased in
SP-D-/- compared with
SP-D+/+ mice (Fig. 5). Control neutrophils isolated from the
blood of uninfected SP-D+/+ mice had
significantly greater MPO activity compared with BAL neutrophils from
IAV-infected SP-D-/- mice and significantly
less MPO activity compared with BAL neutrophils from IAV-infected
SP-D+/+ mice (Fig. 5).
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Concentrations of SP-D in lung homogenates were increased
approximately 2-fold 3 days following IAV infection in
SP-D+/+ mice (Fig. 6). Five days after IAV infection, SP-D
concentrations in the lung of infected SP-D+/+
mice decreased to concentrations similar to those in uninfected
SP-D+/+ mice.
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Discussion |
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TopAbstractIntroductionMaterials and MethodsResultsDiscussionReferences |
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Impaired clearance of IAV from the lungs of SP-D-/- mice supports the importance of SP-D in host defense. SP-D is a member of the C-type lectin family of polypeptides that includes mannose binding protein, conglutinin, and SP-A. C-type lectins share structural features, including collagenous N-terminal and globular C-terminal domains, the latter serving as a carbohydrate recognition domain that functions in opsonization. In the presence of calcium, SP-D binds to a variety of glycoconjugates, including di- and monosaccharides such as maltose, glucose, and mannose (2). Influenza virus has two membrane glycoproteins, hemagglutinin and neuraminidase. Collectins bind to oligosaccharides on influenza virus glycoproteins and neutralize virus infectivity in vitro; more heavily glycosylated strains of viruses are the most sensitive (27). SP-D may enhance viral clearance by binding to the carbohydrate side chain of IAV, blocking access of cell surface receptors to the receptor binding site and thus interfering with virus internalization by host cells, or it may inhibit viral replication at a later stage within the cell. In addition, SP-D binds and agglutinates IAV, which may in part enhance viral removal from the lung through mucociliary and phagocytic clearance. However, the finding that uptake of the virus by alveolar macrophages is not reduced suggests that SP-D binding, aggregation, and uptake by the alveolar macrophages are not critical determinants of the decreased viral killing noted in SP-D-/- mice.
Phagocytosis of IAV by alveolar macrophages was similar for SP-D-/- and wild-type mice in vivo. Since macrophage phagocytosis is part of the early, nonspecific immune response, an early time point was chosen to assess macrophage phagocytosis; however, the optimal time point for assessing viral phagocytosis by macrophages in unknown. In addition, large quantities of ingested FITC-labeled virus are necessary to detect macrophage fluorescence. As indicated in the introduction, previous studies have suggested that SP-D does not enhance the uptake of some strains of IAV by alveolar macrophages in vitro (22). In the absence of SP-D, macrophage phagocytosis of IAV was similar to that in wild-type mice, suggesting that SP-D is not a critical determinant for macrophage clearance of IAV in vivo.
After IAV infection, markers of inflammation, including inflammatory
cells and cytokines, were increased in the lungs of
SP-D-/- mice, and exogenous recombinant SP-D
reduced IAV-induced cytokine production.
SP-D-/- mice are able to mount an immune
response to IAV infection; however, the response is greatly increased
compared with that of wild-type controls. Increased cytokine production
may reflect increased cells in BALF after viral infection. Uninfected
SP-D-/- mice have modestly increased numbers of
alveolar macrophages in the lung; however, proinflammatory cytokine
concentrations are not substantially increased (28).
Increased cytokines, TNF-, IL-1, IL-6, and IFN-, have been
demonstrated in a mouse model of IAV infection associated with
lymphocytic and mononuclear infiltrates in the lung (29).
The cytokine response to IAV was similar in
SP-D-/- mice with elevated TNF-, IL-1,
IL-6, and IFN- levels; however, pulmonary cytokine responses to IAV
were significantly greater in SP-D-/- mice than
in wild-type mice. Augmented inflammatory responses have also been
observed following bacterial challenge (26). These
findings are consistent with our general hypothesis that SP-D plays
important anti-inflammatory roles in vivo. It is possible that
these effects serve to minimize collateral damage to lung tissue while
enhancing uptake or clearance.
Cytotoxic T cells play an important role in IAV clearance from the lung by direct cytolysis of virus-infected cells (18). In vitro, SP-D inhibits IL-2-dependent, mitogen-stimulated, T lymphocyte proliferation (30). In the absence of SP-D, the percentages of CD4 and CD8 T lymphocytes in BALF were similar to those in wild-type mice after IAV infection. The current study examined the number of T lymphocytes present in BAL fluid following IAV infection; however, the function and activation state of the T lymphocytes were not examined. In addition, an early time point was chosen to examine T lymphocytes in BAL fluid, which may have failed to recognize the difference in the specific T lymphocyte response that occurs later after IAV infection.
After IAV infection, pulmonary neutrophil accumulation was greater in SP-D-/- mice then in wild-type mice. However, neutrophil MPO activity normalized per cell was decreased after IAV infection in SP-D-deficient mice. Because the levels were normal in blood neutrophils, it is likely that the recruited cells have undergone a greater degree of degranulation in response to the viral challenge in the absence of SP-D. Defects in neutrophil chemotactic, oxidative, and bacterial killing functions have been documented in IAV infection (31). In addition, it has been shown in animal models that there is a correlation between impairment of the function of these cells and predisposition to bacterial superinfection (32). SP-D enhances the uptake and specific oxidative response to internalized virus in vitro. In addition, SP-D decreases the inhibitory effects of IAV on neutrophil respiratory burst responses (14). Although the effects of SP-D and IAV on neutrophil degranulation and MPO activity have not yet been characterized in vitro, the findings emphasize the potential importance of neutrophils for the initial host response to IAV and suggest that SP-D may alter the neutrophil response to internalized virus.
In summary, in the absence of SP-D, IAV viral clearance from the lung was impaired. Lung inflammation was more severe in SP-D-/- mice, suggesting that SP-D plays a role in modulating cytokine production and inflammatory responses during viral infection. In addition, SP-D binds and agglutinates IAV that may also play a role by enhancing IAV removal from the lung through mucociliary clearance and enhanced recruitment and activation of polymorphonuclear leukocytes. Since the airway is the usual portal of entry for influenza virus and other respiratory pathogens, the local production of SP-D is likely to play a role in innate defense responses to inhaled viruses.
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Acknowledgments |
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Footnotes |
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2 Address correspondence and reprint requests to Dr. Ann Marie LeVine, Division of Pulmonary Biology, Children’s Hospital Medical Center, 3333 Burnet Avenue, Cincinnati, OH 45229-3039. E-mail address: levia0{at}chmcc.org
3 Abbreviations used in this paper: SP-D, surfactant protein D; SP-A, surfactant protein A; BAL, bronchoalveolar lavage; BALF, bronchoalveolar lavage fluid; ff, fluorescent foci; IAV, influenza A virus; MIP-2, macrophage-inflammatory protein 2; MPO, myeloperoxidase.
Received for publication June 25, 2001. Accepted for publication September 19, 2001.
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J. Casey, J. Kaplan, E. N. Atochina-Vasserman, A. J. Gow, H. Kadire, Y. Tomer, J. H. Fisher, S. Hawgood, R. C. Savani, and M. F. Beers Alveolar Surfactant Protein D Content Modulates Bleomycin-induced Lung Injury Am. J. Respir. Crit. Care Med., October 1, 2005; 172(7): 869 - 877. [Abstract] [Full Text] [PDF]
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M. R. White, E. Crouch, J. Vesona, P. J. Tacken, J. J. Batenburg, R. Leth-Larsen, U. Holmskov, and K. L. Hartshorn Respiratory innate immune proteins differentially modulate the neutrophil respiratory burst response to influenza A virus Am J Physiol Lung Cell Mol Physiol, October 1, 2005; 289(4): L606 - L616. [Abstract] [Full Text] [PDF]
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S. Teske, A. A. Bohn, J. F. Regal, J. J. Neumiller, and B. P. Lawrence Activation of the aryl hydrocarbon receptor increases pulmonary neutrophilia and diminishes host resistance to influenza A virus Am J Physiol Lung Cell Mol Physiol, July 1, 2005; 289(1): L111 - L124. [Abstract] [Full Text] [PDF]
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T. Madan, K. B. M. Reid, M. Singh, P. U. Sarma, and U. Kishore Susceptibility of Mice Genetically Deficient in the Surfactant Protein (SP)-A or SP-D Gene to Pulmonary Hypersensitivity Induced by Antigens and Allergens of Aspergillus fumigatus J. Immunol., June 1, 2005; 174(11): 6943 - 6954. [Abstract] [Full Text] [PDF]
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M. R. White, E. Crouch, M. van Eijk, M. Hartshorn, L. Pemberton, I. Tornoe, U. Holmskov, and K. L. Hartshorn Cooperative anti-influenza activities of respiratory innate immune proteins and neuraminidase inhibitor Am J Physiol Lung Cell Mol Physiol, May 1, 2005; 288(5): L831 - L840. [Abstract] [Full Text] [PDF]
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E. Crouch, Y. Tu, D. Briner, B. McDonald, K. Smith, U. Holmskov, and K. Hartshorn Ligand Specificity of Human Surfactant Protein D: EXPRESSION OF A MUTANT TRIMERIC COLLECTIN THAT SHOWS ENHANCED INTERACTIONS WITH INFLUENZA A VIRUS J. Biol. Chem., April 29, 2005; 280(17): 17046 - 17056. [Abstract] [Full Text] [PDF]
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 L. M. Schaeffer, F. X. McCormack, H. Wu, and A. A. Weiss Interactions of Pulmonary Collectins with Bordetella bronchiseptica and Bordetella pertussis Lipopolysaccharide Elucidate the Structural Basis of Their Antimicrobial Activities Infect. Immun., December 1, 2004; 72(12): 7124 - 7130. [Abstract] [Full Text] [PDF]
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 R. E. Oberley, K. L. Goss, K. A. Ault, E. C. Crouch, and J. M. Snyder Surfactant protein D is present in the human female reproductive tract and inhibits Chlamydia trachomatis infection Mol. Hum. Reprod., December 1, 2004; 10(12): 861 - 870. [Abstract] [Full Text] [PDF]
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S.-Z. Wang, Y.-X. Bao, C. L. Rosenberger, Y. Tesfaigzi, J. M. Stark, and K. S. Harrod IL-12p40 and IL-18 Modulate Inflammatory and Immune Responses to Respiratory Syncytial Virus Infection J. Immunol., September 15, 2004; 173(6): 4040 - 4049. [Abstract] [Full Text] [PDF]
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 S. Hawgood, C. Brown, J. Edmondson, A. Stumbaugh, L. Allen, J. Goerke, H. Clark, and F. Poulain Pulmonary Collectins Modulate Strain-Specific Influenza A Virus Infection and Host Responses J. Virol., August 15, 2004; 78(16): 8565 - 8572. [Abstract] [Full Text] [PDF]
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 A. M. LeVine, J. Elliott, J. A. Whitsett, A. Srikiatkhachorn, E. Crouch, N. DeSilva, and T. Korfhagen Surfactant Protein-D Enhances Phagocytosis and Pulmonary Clearance of Respiratory Syncytial Virus Am. J. Respir. Cell Mol. Biol., August 1, 2004; 31(2): 193 - 199. [Abstract] [Full Text] [PDF]
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R. E. Oberley, K. A. Ault, T. L. Neff, K. R. Khubchandani, E. C. Crouch, and J. M. Snyder Surfactant proteins A and D enhance the phagocytosis of Chlamydia into THP-1 cells Am J Physiol Lung Cell Mol Physiol, August 1, 2004; 287(2): L296 - L306. [Abstract] [Full Text] [PDF]
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J. F. Alcorn and J. R. Wright Degradation of Pulmonary Surfactant Protein D by Pseudomonas aeruginosa Elastase Abrogates Innate Immune Function J. Biol. Chem., July 16, 2004; 279(29): 30871 - 30879. [Abstract] [Full Text] [PDF]
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T. O. Hirche, E. C. Crouch, M. Espinola, T. J. Brokelman, R. P. Mecham, N. DeSilva, J. Cooley, E. Remold-O'Donnell, and A. Belaaouaj Neutrophil Serine Proteinases Inactivate Surfactant Protein D by Cleaving within a Conserved Subregion of the Carbohydrate Recognition Domain J. Biol. Chem., June 25, 2004; 279(26): 27688 - 27698. [Abstract] [Full Text] [PDF]
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M. van Eijk, M. R. White, J. J. Batenburg, A. B. Vaandrager, L. M. G. van Golde, H. P. Haagsman, and K. L. Hartshorn Interactions of Influenza A Virus with Sialic Acids Present on Porcine Surfactant Protein D Am. J. Respir. Cell Mol. Biol., June 1, 2004; 30(6): 871 - 879. [Abstract] [Full Text] [PDF]
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 P. Prodhan and N. Noviski Pediatric Acute Hypoxemic Respiratory Failure: Management of Oxygenation J Intensive Care Med, May 1, 2004; 19(3): 140 - 153. [Abstract] [PDF]
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K. L. Hartshorn, M. R. White, T. Mogues, T. Ligtenberg, E. Crouch, and U. Holmskov Lung and salivary scavenger receptor glycoprotein-340 contribute to the host defense against influenza A viruses Am J Physiol Lung Cell Mol Physiol, November 1, 2003; 285(5): L1066 - L1076. [Abstract] [Full Text] [PDF]
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M. van Eijk, M. R. White, E. C. Crouch, J. J. Batenburg, A. B. Vaandrager, L. M. G. van Golde, H. P. Haagsman, and K. L. Hartshorn Porcine Pulmonary Collectins Show Distinct Interactions with Influenza A Viruses: Role of the N-Linked Oligosaccharides in the Carbohydrate Recognition Domain J. Immunol., August 1, 2003; 171(3): 1431 - 1440. [Abstract] [Full Text] [PDF]
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 Z. Lin and J. Floros Heterogeneous allele expression of pulmonary SP-D gene in rat large intestine and other tissues Physiol Genomics, December 3, 2002; 11(3): 235 - 243. [Abstract] [Full Text] [PDF]
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K. L. Hartshorn, M. R. White, and E. C. Crouch Contributions of the N- and C-Terminal Domains of Surfactant Protein D to the Binding, Aggregation, and Phagocytic Uptake of Bacteria Infect. Immun., November 1, 2002; 70(11): 6129 - 6139. [Abstract] [Full Text] [PDF]
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L. Zhang, M. Ikegami, C. R. Dey, T. R. Korfhagen, and J. A. Whitsett Reversibility of Pulmonary Abnormalities by Conditional Replacement of Surfactant Protein D (SP-D) in Vivo J. Biol. Chem., October 4, 2002; 277(41): 38709 - 38713. [Abstract] [Full Text] [PDF]
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N. Palaniyar, L. Zhang, A. Kuzmenko, M. Ikegami, S. Wan, H. Wu, T. R. Korfhagen, J. A. Whitsett, and F. X. McCormack The Role of Pulmonary Collectin N-terminal Domains in Surfactant Structure, Function, and Homeostasis in Vivo J. Biol. Chem., July 19, 2002; 277(30): 26971 - 26979. [Abstract] [Full Text] [PDF]
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 J. Akiyama, A. Hoffman, C. Brown, L. Allen, J. Edmondson, F. Poulain, and S. Hawgood Tissue Distribution of Surfactant Proteins A and D in the Mouse J. Histochem. Cytochem., July 1, 2002; 50(7): 993 - 996. [Abstract] [Full Text] [PDF]
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M. T. Stahlman, M. E. Gray, W. M. Hull, and J. A. Whitsett Immunolocalization of Surfactant Protein-D (SP-D) in Human Fetal, Newborn, and Adult Tissues J. Histochem. Cytochem., May 1, 2002; 50(5): 651 - 660. [Abstract] [Full Text] [PDF]
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V. L. Shepherd Distinct Roles for Lung Collectins in Pulmonary Host Defense Am. J. Respir. Cell Mol. Biol., March 1, 2002; 26(3): 257 - 260. [Full Text] [PDF]
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A. M. LeVine, K. Hartshorn, J. Elliott, J. Whitsett, and T. Korfhagen Absence of SP-A modulates innate and adaptive defense responses to pulmonary influenza infection Am J Physiol Lung Cell Mol Physiol, March 1, 2002; 282(3): L563 - L572. [Abstract] [Full Text] [PDF]
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) and SP-D+/+ (
) mice
(A). SP-D-/- mice had increased total
cell counts in BAL fluid 3 and 5 days after IAV infection compared with
SP-D+/+ mice (A). The percentage of
neutrophils in BAL fluid was significantly greater 3 and 5 days after
administration of 105 ff IAV to SP-D-/- (
) compared with
untreated SP-D-/- (
) mice had significantly greater MPO activity
compared with SP-D-/- BAL neutrophils and less MPO
activity compared with SP-D+/+ BAL neutrophils after
infection (B). Data are means ± SEM
(n = 8 mice/group). *, p <
0.05 compared with SP-D+/+ mice.