Limits...
Surfactant protein-A suppresses eosinophil-mediated killing of Mycoplasma pneumoniae in allergic lungs.

Ledford JG, Mukherjee S, Kislan MM, Nugent JL, Hollingsworth JW, Wright JR - PLoS ONE (2012)

Bottom Line: Thus, SP-A could protect allergic airways from injury due to release of eosinophil inflammatory products.In vitro experiments using purified eosinophils and human SP-A suggest that SP-A limits the release of EPO from Mp-stimulated eosinophils thereby reducing their killing capacity.These findings are the first to demonstrate that although SP-A interferes with eosinophil-mediated biologic clearance of Mp by mediating the interaction of Mp with eosinophils, SP-A simultaneously benefits the airway by limiting inflammation and damage.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, United States of America. j.ledford@cellbio.duke.edu

ABSTRACT
Surfactant protein-A (SP-A) has well-established functions in reducing bacterial and viral infections but its role in chronic lung diseases such as asthma is unclear. Mycoplasma pneumoniae (Mp) frequently colonizes the airways of chronic asthmatics and is thought to contribute to exacerbations of asthma. Our lab has previously reported that during Mp infection of non-allergic airways, SP-A aides in maintaining airway homeostasis by inhibiting an overzealous TNF-alpha mediated response and, in allergic mice, SP-A regulates eosinophilic infiltration and inflammation of the airway. In the current study, we used an in vivo model with wild type (WT) and SP-A(-/-) allergic mice challenged with the model antigen ovalbumin (Ova) that were concurrently infected with Mp (Ova+Mp) to test the hypothesis that SP-A ameliorates Mp-induced stimulation of eosinophils. Thus, SP-A could protect allergic airways from injury due to release of eosinophil inflammatory products. SP-A deficient mice exhibit significant increases in inflammatory cells, mucus production and lung damage during concurrent allergic airway disease and infection (Ova+Mp) as compared to the WT mice of the same treatment group. In contrast, SP-A deficient mice have significantly decreased Mp burden compared to WT mice. The eosinophil specific factor, eosinophil peroxidase (EPO), which has been implicated in pathogen killing and also in epithelial dysfunction due to oxidative damage of resident lung proteins, is enhanced in samples from allergic/infected SP-A(-/-) mice as compared to WT mice. In vitro experiments using purified eosinophils and human SP-A suggest that SP-A limits the release of EPO from Mp-stimulated eosinophils thereby reducing their killing capacity. These findings are the first to demonstrate that although SP-A interferes with eosinophil-mediated biologic clearance of Mp by mediating the interaction of Mp with eosinophils, SP-A simultaneously benefits the airway by limiting inflammation and damage.

Show MeSH

Related in: MedlinePlus

Eosinophil mediators are increased in the absence of SP-A.On day 28 of the Ova+Mp model, lungs were harvested and A) IL-5 and B) EAR were assessed by RT-PCR. C) Histochemical staining for EPO positive eosinophils was done 1 day after Mp infection and is representative of 3 experiments, n = 5/group. D) Total EPO activity in BAL and lung tissue from Ova+Mp mice was determined via colorimetric assay and absorbance read at 492 nm. n = combined 3 experiments, *p<.05, **p<.01.
© Copyright Policy
Related In: Results  -  Collection


getmorefigures.php?uid=PMC3285686&req=5

pone-0032436-g003: Eosinophil mediators are increased in the absence of SP-A.On day 28 of the Ova+Mp model, lungs were harvested and A) IL-5 and B) EAR were assessed by RT-PCR. C) Histochemical staining for EPO positive eosinophils was done 1 day after Mp infection and is representative of 3 experiments, n = 5/group. D) Total EPO activity in BAL and lung tissue from Ova+Mp mice was determined via colorimetric assay and absorbance read at 492 nm. n = combined 3 experiments, *p<.05, **p<.01.

Mentions: Lungs were harvested from three groups of WT and SP-A mice: 1) saline treated control mice, 2) Ova sensitized/challenged mice, 3) and Ova sensitized/challenged and Mp infected mice. To determine if SP-A regulates eosinophil activation to Mp infection in the allergic mice, markers of eosinophils, such as IL-5 and eosinophil associated ribonuclease (EAR), were analyzed by RT-PCR. In Ova allergic WT and SP-A−/− mice, the levels of IL-5 and EAR RNA were dramatically but comparably increased over levels detected in samples taken from saline treated mice, suggesting similar numbers eosinophils were present in the lungs of WT and SP-A−/− mice 5 days post Ova challenge. Interestingly, EAR expression, a marker typically associated with eosinophil activation, is significantly increased in the WT Ova+Mp compared to the WT Ova alone. This increase in EAR expression suggests that while the total eosinophil number is similar between the WT groups, the activation status of the eosinophils, as determined at the transcriptional level, in the WT Ova+Mp group is greater than in the WT Ova only. Additionally, when Ova allergic SP-A−/− mice are infected with Mp, the levels of IL-5 and EAR RNA significantly increased over levels detected in the Ova allergic WT infected mice. This suggests that not only are more eosinophils present in the SP-A−/− Ova+Mp mice, but also that SP-A may reduce the activation of eosinophils at the transcriptional level (fig. 3A,B).


Surfactant protein-A suppresses eosinophil-mediated killing of Mycoplasma pneumoniae in allergic lungs.

Ledford JG, Mukherjee S, Kislan MM, Nugent JL, Hollingsworth JW, Wright JR - PLoS ONE (2012)

Eosinophil mediators are increased in the absence of SP-A.On day 28 of the Ova+Mp model, lungs were harvested and A) IL-5 and B) EAR were assessed by RT-PCR. C) Histochemical staining for EPO positive eosinophils was done 1 day after Mp infection and is representative of 3 experiments, n = 5/group. D) Total EPO activity in BAL and lung tissue from Ova+Mp mice was determined via colorimetric assay and absorbance read at 492 nm. n = combined 3 experiments, *p<.05, **p<.01.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3285686&req=5

pone-0032436-g003: Eosinophil mediators are increased in the absence of SP-A.On day 28 of the Ova+Mp model, lungs were harvested and A) IL-5 and B) EAR were assessed by RT-PCR. C) Histochemical staining for EPO positive eosinophils was done 1 day after Mp infection and is representative of 3 experiments, n = 5/group. D) Total EPO activity in BAL and lung tissue from Ova+Mp mice was determined via colorimetric assay and absorbance read at 492 nm. n = combined 3 experiments, *p<.05, **p<.01.
Mentions: Lungs were harvested from three groups of WT and SP-A mice: 1) saline treated control mice, 2) Ova sensitized/challenged mice, 3) and Ova sensitized/challenged and Mp infected mice. To determine if SP-A regulates eosinophil activation to Mp infection in the allergic mice, markers of eosinophils, such as IL-5 and eosinophil associated ribonuclease (EAR), were analyzed by RT-PCR. In Ova allergic WT and SP-A−/− mice, the levels of IL-5 and EAR RNA were dramatically but comparably increased over levels detected in samples taken from saline treated mice, suggesting similar numbers eosinophils were present in the lungs of WT and SP-A−/− mice 5 days post Ova challenge. Interestingly, EAR expression, a marker typically associated with eosinophil activation, is significantly increased in the WT Ova+Mp compared to the WT Ova alone. This increase in EAR expression suggests that while the total eosinophil number is similar between the WT groups, the activation status of the eosinophils, as determined at the transcriptional level, in the WT Ova+Mp group is greater than in the WT Ova only. Additionally, when Ova allergic SP-A−/− mice are infected with Mp, the levels of IL-5 and EAR RNA significantly increased over levels detected in the Ova allergic WT infected mice. This suggests that not only are more eosinophils present in the SP-A−/− Ova+Mp mice, but also that SP-A may reduce the activation of eosinophils at the transcriptional level (fig. 3A,B).

Bottom Line: Thus, SP-A could protect allergic airways from injury due to release of eosinophil inflammatory products.In vitro experiments using purified eosinophils and human SP-A suggest that SP-A limits the release of EPO from Mp-stimulated eosinophils thereby reducing their killing capacity.These findings are the first to demonstrate that although SP-A interferes with eosinophil-mediated biologic clearance of Mp by mediating the interaction of Mp with eosinophils, SP-A simultaneously benefits the airway by limiting inflammation and damage.

View Article: PubMed Central - PubMed

Affiliation: Department of Cell Biology, Duke University Medical Center, Durham, North Carolina, United States of America. j.ledford@cellbio.duke.edu

ABSTRACT
Surfactant protein-A (SP-A) has well-established functions in reducing bacterial and viral infections but its role in chronic lung diseases such as asthma is unclear. Mycoplasma pneumoniae (Mp) frequently colonizes the airways of chronic asthmatics and is thought to contribute to exacerbations of asthma. Our lab has previously reported that during Mp infection of non-allergic airways, SP-A aides in maintaining airway homeostasis by inhibiting an overzealous TNF-alpha mediated response and, in allergic mice, SP-A regulates eosinophilic infiltration and inflammation of the airway. In the current study, we used an in vivo model with wild type (WT) and SP-A(-/-) allergic mice challenged with the model antigen ovalbumin (Ova) that were concurrently infected with Mp (Ova+Mp) to test the hypothesis that SP-A ameliorates Mp-induced stimulation of eosinophils. Thus, SP-A could protect allergic airways from injury due to release of eosinophil inflammatory products. SP-A deficient mice exhibit significant increases in inflammatory cells, mucus production and lung damage during concurrent allergic airway disease and infection (Ova+Mp) as compared to the WT mice of the same treatment group. In contrast, SP-A deficient mice have significantly decreased Mp burden compared to WT mice. The eosinophil specific factor, eosinophil peroxidase (EPO), which has been implicated in pathogen killing and also in epithelial dysfunction due to oxidative damage of resident lung proteins, is enhanced in samples from allergic/infected SP-A(-/-) mice as compared to WT mice. In vitro experiments using purified eosinophils and human SP-A suggest that SP-A limits the release of EPO from Mp-stimulated eosinophils thereby reducing their killing capacity. These findings are the first to demonstrate that although SP-A interferes with eosinophil-mediated biologic clearance of Mp by mediating the interaction of Mp with eosinophils, SP-A simultaneously benefits the airway by limiting inflammation and damage.

Show MeSH
Related in: MedlinePlus