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Secreted osteopontin is highly polymerized in human airways and fragmented in asthmatic airway secretions.

Arjomandi M, Frelinger J, Donde A, Wong H, Yellamilli A, Raymond W - PLoS ONE (2011)

Bottom Line: Furthermore, we examined the relationship between airway sOPN and cellular inflammation.We found that sOPN in BAL fluid and sputum exists in polymeric, monomeric, and cleaved forms, with most of it in polymeric form.Compared to healthy subjects, asthmatic subjects had proportionately less polymeric sOPN and more monomeric and cleaved sOPN.

View Article: PubMed Central - PubMed

Affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California San Francisco, San Francisco, California, United States of America. mehrdad.arjomandi@ucsf.edu

ABSTRACT

Background: Osteopontin (OPN) is a member of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family and a cytokine with diverse biologic roles. OPN undergoes extensive post-translational modifications, including polymerization and proteolytic fragmentation, which alters its biologic activity. Recent studies suggest that OPN may contribute to the pathogenesis of asthma.

Methodology: To determine whether secreted OPN (sOPN) is polymerized in human airways and whether it is qualitatively different in asthma, we used immunoblotting to examine sOPN in bronchoalveolar lavage (BAL) fluid samples from 12 healthy and 21 asthmatic subjects (and in sputum samples from 27 healthy and 21 asthmatic subjects). All asthmatic subjects had mild to moderate asthma and abstained from corticosteroids during the study. Furthermore, we examined the relationship between airway sOPN and cellular inflammation.

Principal findings: We found that sOPN in BAL fluid and sputum exists in polymeric, monomeric, and cleaved forms, with most of it in polymeric form. Compared to healthy subjects, asthmatic subjects had proportionately less polymeric sOPN and more monomeric and cleaved sOPN. Polymeric sOPN in BAL fluid was associated with increased alveolar macrophage counts in airways in all subjects.

Conclusions: These results suggest that sOPN in human airways (1) undergoes extensive post-translational modification by polymerization and proteolytic fragmentation, (2) is more fragmented and less polymerized in subjects with mild to moderate asthma, and (3) may contribute to recruitment or survival of alveolar macrophages.

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Deglycosylation and dephosphorylation of rOPN and BAL and sputum sOPN.Immunoblot of deglycosylation and dephosphorylation of rOPN and sputum supernatant sOPN (2A) and BAL fluid sOPN from representative subjects (2B) probed with polyclonal anti-human sOPN antibody. DeGly: Deglycosylation Enzyme Mix; Alk Phos: Alkaline Phosphatase.
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pone-0025678-g002: Deglycosylation and dephosphorylation of rOPN and BAL and sputum sOPN.Immunoblot of deglycosylation and dephosphorylation of rOPN and sputum supernatant sOPN (2A) and BAL fluid sOPN from representative subjects (2B) probed with polyclonal anti-human sOPN antibody. DeGly: Deglycosylation Enzyme Mix; Alk Phos: Alkaline Phosphatase.

Mentions: Deglycosylation and dephosphorylation of rOPN decreased the size of the rOPN band from 55 kD to 50 kD (Figure 2A). Similarly, treatment of BAL samples showed the appearance of a second band of sOPN at 50 kD (Figure 2B). In addition, the deglycosylation and dephosphorylation caused an analogous shift in the 90 kD band of sOPN down to about 80 kD. No significant changes were observed in the polymeric sOPN band in BAL. The sputum samples showed a similar pattern of shift in their bands (Figure 2A).


Secreted osteopontin is highly polymerized in human airways and fragmented in asthmatic airway secretions.

Arjomandi M, Frelinger J, Donde A, Wong H, Yellamilli A, Raymond W - PLoS ONE (2011)

Deglycosylation and dephosphorylation of rOPN and BAL and sputum sOPN.Immunoblot of deglycosylation and dephosphorylation of rOPN and sputum supernatant sOPN (2A) and BAL fluid sOPN from representative subjects (2B) probed with polyclonal anti-human sOPN antibody. DeGly: Deglycosylation Enzyme Mix; Alk Phos: Alkaline Phosphatase.
© Copyright Policy
Related In: Results  -  Collection

Show All Figures
getmorefigures.php?uid=PMC3198733&req=5

pone-0025678-g002: Deglycosylation and dephosphorylation of rOPN and BAL and sputum sOPN.Immunoblot of deglycosylation and dephosphorylation of rOPN and sputum supernatant sOPN (2A) and BAL fluid sOPN from representative subjects (2B) probed with polyclonal anti-human sOPN antibody. DeGly: Deglycosylation Enzyme Mix; Alk Phos: Alkaline Phosphatase.
Mentions: Deglycosylation and dephosphorylation of rOPN decreased the size of the rOPN band from 55 kD to 50 kD (Figure 2A). Similarly, treatment of BAL samples showed the appearance of a second band of sOPN at 50 kD (Figure 2B). In addition, the deglycosylation and dephosphorylation caused an analogous shift in the 90 kD band of sOPN down to about 80 kD. No significant changes were observed in the polymeric sOPN band in BAL. The sputum samples showed a similar pattern of shift in their bands (Figure 2A).

Bottom Line: Furthermore, we examined the relationship between airway sOPN and cellular inflammation.We found that sOPN in BAL fluid and sputum exists in polymeric, monomeric, and cleaved forms, with most of it in polymeric form.Compared to healthy subjects, asthmatic subjects had proportionately less polymeric sOPN and more monomeric and cleaved sOPN.

View Article: PubMed Central - PubMed

Affiliation: Division of Pulmonary and Critical Care Medicine, Department of Medicine, University of California San Francisco, San Francisco, California, United States of America. mehrdad.arjomandi@ucsf.edu

ABSTRACT

Background: Osteopontin (OPN) is a member of the small integrin-binding ligand N-linked glycoprotein (SIBLING) family and a cytokine with diverse biologic roles. OPN undergoes extensive post-translational modifications, including polymerization and proteolytic fragmentation, which alters its biologic activity. Recent studies suggest that OPN may contribute to the pathogenesis of asthma.

Methodology: To determine whether secreted OPN (sOPN) is polymerized in human airways and whether it is qualitatively different in asthma, we used immunoblotting to examine sOPN in bronchoalveolar lavage (BAL) fluid samples from 12 healthy and 21 asthmatic subjects (and in sputum samples from 27 healthy and 21 asthmatic subjects). All asthmatic subjects had mild to moderate asthma and abstained from corticosteroids during the study. Furthermore, we examined the relationship between airway sOPN and cellular inflammation.

Principal findings: We found that sOPN in BAL fluid and sputum exists in polymeric, monomeric, and cleaved forms, with most of it in polymeric form. Compared to healthy subjects, asthmatic subjects had proportionately less polymeric sOPN and more monomeric and cleaved sOPN. Polymeric sOPN in BAL fluid was associated with increased alveolar macrophage counts in airways in all subjects.

Conclusions: These results suggest that sOPN in human airways (1) undergoes extensive post-translational modification by polymerization and proteolytic fragmentation, (2) is more fragmented and less polymerized in subjects with mild to moderate asthma, and (3) may contribute to recruitment or survival of alveolar macrophages.

Show MeSH
Related in: MedlinePlus