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Regulation of hepatocyte growth factor in mice with pneumonia by peptidases and trans-alveolar flux.

Raymond WW, Xu X, Nimishakavi S, Le C, McDonald DM, Caughey GH - PLoS ONE (2015)

Bottom Line: These findings are consistent with trans-alveolar flux rather than local production as the source of increased HGF in lavage fluid.Consistent with the presence of active HGF, increased expression of activated receptor c-Met was observed in infected tissues.These data suggest that HGF entering alveoli from the bloodstream during pneumonia compensates for destruction by Dppi-activated inflammatory proteases to allow HGF to contribute to epithelial repair.

View Article: PubMed Central - PubMed

Affiliation: Cardiovascular Research Institute, School of Medicine, University of California San Francisco, San Francisco, California, United States of America.

ABSTRACT
Hepatocyte growth factor (HGF) promotes lung epithelial repair after injury. Because prior studies established that human neutrophil proteases inactivate HGF in vitro, we predicted that HGF levels decrease in lungs infiltrated with neutrophils and that injury is less severe in lungs lacking HGF-inactivating proteases. After establishing that mouse neutrophil elastase cleaves mouse HGF in vitro, we tested our predictions in vivo by examining lung pathology and HGF in mice infected with Mycoplasma pulmonis, which causes neutrophilic tracheobronchitis and pneumonia. Unexpectedly, pneumonia severity was similar in wild type and dipeptidylpeptidase I-deficient (Dppi-/-) mice lacking neutrophil serine protease activity. To assess how this finding related to our prediction that Dppi-activated proteases regulate HGF levels, we measured HGF in serum, bronchoalveolar lavage fluid, and lung tissue from Dppi(+/+) and Dppi(-/-) mice. Contrary to prediction, HGF levels were higher in lavage fluid from infected mice. However, serum and tissue concentrations were not different in infected and uninfected mice, and HGF lung transcript levels did not change. Increased HGF correlated with increased albumin in lavage fluid from infected mice, and immunostaining failed to detect increased lung tissue expression of HGF in infected mice. These findings are consistent with trans-alveolar flux rather than local production as the source of increased HGF in lavage fluid. However, levels of intact HGF from infected mice, normalized for albumin concentration, were two-fold higher in Dppi(-/-) versus Dppi(+/+) lavage fluid, suggesting regulation by Dppi-activated proteases. Consistent with the presence of active HGF, increased expression of activated receptor c-Met was observed in infected tissues. These data suggest that HGF entering alveoli from the bloodstream during pneumonia compensates for destruction by Dppi-activated inflammatory proteases to allow HGF to contribute to epithelial repair.

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Measurement of HGF levels in BALF and serum by ELISA.Immunoreactive HGF was measured in BALF (A) and serum (B) from Dppi-/- and Dppi+/+ mice that were sham-infected or Mycoplasma pulmonis-infected two days before acquiring samples. Bars show mean ± SD. Panel C shows relationship between HGF and albumin concentrations in paired samples of BALF. Symbols are as in panels A and B. Panel D shows results of HGF ELISA of extracts of saline-perfused whole lung. For measurements in BALF, P = 0.015 as assessed by Kruskal Wallis one-way ANOVA. Differences in levels of HGF in serum and whole lung extracts were not significant.
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pone.0125797.g003: Measurement of HGF levels in BALF and serum by ELISA.Immunoreactive HGF was measured in BALF (A) and serum (B) from Dppi-/- and Dppi+/+ mice that were sham-infected or Mycoplasma pulmonis-infected two days before acquiring samples. Bars show mean ± SD. Panel C shows relationship between HGF and albumin concentrations in paired samples of BALF. Symbols are as in panels A and B. Panel D shows results of HGF ELISA of extracts of saline-perfused whole lung. For measurements in BALF, P = 0.015 as assessed by Kruskal Wallis one-way ANOVA. Differences in levels of HGF in serum and whole lung extracts were not significant.

Mentions: As shown in Fig 3A, levels of HGF assessed by ELISA increased approximately 15-fold in Dppi-/- and Dppi+/+ mice after infection compared to baseline in uninfected Dppi+/+ mice. HGF levels also were somewhat higher in uninfected Dppi-/- mice than in Dppi+/+ mice, consistent with a role for Dppi-activated proteases in regulating baseline levels of immunoreactive HGF in BALF. However, as shown in Fig 3B and 3D, no significant differences in levels of immunoreactive HGF were seen in serum or lung tissues between uninfected and infected groups of mice. In uninfected Dppi+/+ mice, the mean concentration of HGF was 195-fold higher in serum than in BALF. However, in infected Dppi+/+ mice, the difference was only 14-fold.


Regulation of hepatocyte growth factor in mice with pneumonia by peptidases and trans-alveolar flux.

Raymond WW, Xu X, Nimishakavi S, Le C, McDonald DM, Caughey GH - PLoS ONE (2015)

Measurement of HGF levels in BALF and serum by ELISA.Immunoreactive HGF was measured in BALF (A) and serum (B) from Dppi-/- and Dppi+/+ mice that were sham-infected or Mycoplasma pulmonis-infected two days before acquiring samples. Bars show mean ± SD. Panel C shows relationship between HGF and albumin concentrations in paired samples of BALF. Symbols are as in panels A and B. Panel D shows results of HGF ELISA of extracts of saline-perfused whole lung. For measurements in BALF, P = 0.015 as assessed by Kruskal Wallis one-way ANOVA. Differences in levels of HGF in serum and whole lung extracts were not significant.
© Copyright Policy
Related In: Results  -  Collection

License
Show All Figures
getmorefigures.php?uid=PMC4418689&req=5

pone.0125797.g003: Measurement of HGF levels in BALF and serum by ELISA.Immunoreactive HGF was measured in BALF (A) and serum (B) from Dppi-/- and Dppi+/+ mice that were sham-infected or Mycoplasma pulmonis-infected two days before acquiring samples. Bars show mean ± SD. Panel C shows relationship between HGF and albumin concentrations in paired samples of BALF. Symbols are as in panels A and B. Panel D shows results of HGF ELISA of extracts of saline-perfused whole lung. For measurements in BALF, P = 0.015 as assessed by Kruskal Wallis one-way ANOVA. Differences in levels of HGF in serum and whole lung extracts were not significant.
Mentions: As shown in Fig 3A, levels of HGF assessed by ELISA increased approximately 15-fold in Dppi-/- and Dppi+/+ mice after infection compared to baseline in uninfected Dppi+/+ mice. HGF levels also were somewhat higher in uninfected Dppi-/- mice than in Dppi+/+ mice, consistent with a role for Dppi-activated proteases in regulating baseline levels of immunoreactive HGF in BALF. However, as shown in Fig 3B and 3D, no significant differences in levels of immunoreactive HGF were seen in serum or lung tissues between uninfected and infected groups of mice. In uninfected Dppi+/+ mice, the mean concentration of HGF was 195-fold higher in serum than in BALF. However, in infected Dppi+/+ mice, the difference was only 14-fold.

Bottom Line: These findings are consistent with trans-alveolar flux rather than local production as the source of increased HGF in lavage fluid.Consistent with the presence of active HGF, increased expression of activated receptor c-Met was observed in infected tissues.These data suggest that HGF entering alveoli from the bloodstream during pneumonia compensates for destruction by Dppi-activated inflammatory proteases to allow HGF to contribute to epithelial repair.

View Article: PubMed Central - PubMed

Affiliation: Cardiovascular Research Institute, School of Medicine, University of California San Francisco, San Francisco, California, United States of America.

ABSTRACT
Hepatocyte growth factor (HGF) promotes lung epithelial repair after injury. Because prior studies established that human neutrophil proteases inactivate HGF in vitro, we predicted that HGF levels decrease in lungs infiltrated with neutrophils and that injury is less severe in lungs lacking HGF-inactivating proteases. After establishing that mouse neutrophil elastase cleaves mouse HGF in vitro, we tested our predictions in vivo by examining lung pathology and HGF in mice infected with Mycoplasma pulmonis, which causes neutrophilic tracheobronchitis and pneumonia. Unexpectedly, pneumonia severity was similar in wild type and dipeptidylpeptidase I-deficient (Dppi-/-) mice lacking neutrophil serine protease activity. To assess how this finding related to our prediction that Dppi-activated proteases regulate HGF levels, we measured HGF in serum, bronchoalveolar lavage fluid, and lung tissue from Dppi(+/+) and Dppi(-/-) mice. Contrary to prediction, HGF levels were higher in lavage fluid from infected mice. However, serum and tissue concentrations were not different in infected and uninfected mice, and HGF lung transcript levels did not change. Increased HGF correlated with increased albumin in lavage fluid from infected mice, and immunostaining failed to detect increased lung tissue expression of HGF in infected mice. These findings are consistent with trans-alveolar flux rather than local production as the source of increased HGF in lavage fluid. However, levels of intact HGF from infected mice, normalized for albumin concentration, were two-fold higher in Dppi(-/-) versus Dppi(+/+) lavage fluid, suggesting regulation by Dppi-activated proteases. Consistent with the presence of active HGF, increased expression of activated receptor c-Met was observed in infected tissues. These data suggest that HGF entering alveoli from the bloodstream during pneumonia compensates for destruction by Dppi-activated inflammatory proteases to allow HGF to contribute to epithelial repair.

Show MeSH
Related in: MedlinePlus