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Combined exposure to cigarette smoke and nontypeable Haemophilus influenzae drives development of a COPD phenotype in mice.

Ganesan S, Comstock AT, Kinker B, Mancuso P, Beck JM, Sajjan US - Respir. Res. (2014)

Bottom Line: CS/HK-NTHi-exposed mice also expressed increased levels of mucin genes and cytokines compared to mice in other groups.CS/HK-NTHi-exposed mice infected with RV demonstrated increased viral persistence, sustained neutrophilia, and further increments in mucin gene and chemokine expression compared to other groups.These findings indicate that in addition to CS, bacteria may also contribute to development of COPD, particularly changes in airways.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pediatrics and Communicable Diseases, University of Michigan, 1150 W, Medical Center Dr,, Ann Arbor, MI 48109-5688, USA. usajjan@umich.edu.

ABSTRACT

Background: Cigarette smoke (CS) is the major etiologic factor of chronic obstructive pulmonary disease (COPD). CS-exposed mice develop emphysema and mild pulmonary inflammation but no airway obstruction, which is also a prominent feature of COPD. Therefore, CS may interact with other factors, particularly respiratory infections, in the pathogenesis of airway remodeling in COPD.

Methods: C57BL/6 mice were exposed to CS for 2 h a day, 5 days a week for 8 weeks. Mice were also exposed to heat-killed non-typeable H. influenzae (HK-NTHi) on days 7 and 21. One day after the last exposure to CS, mice were sacrificed and lung inflammation and mechanics, emphysematous changes, and goblet cell metaplasia were assessed. Mice exposed to CS or HK-NTHi alone or room air served as controls. To determine the susceptibility to viral infections, we also challenged these mice with rhinovirus (RV).

Results: Unlike mice exposed to CS or HK-NTHi alone, animals exposed to CS/HK-NTHi developed emphysema, lung inflammation and goblet cell metaplasia in both large and small airways. CS/HK-NTHi-exposed mice also expressed increased levels of mucin genes and cytokines compared to mice in other groups. CS/HK-NTHi-exposed mice infected with RV demonstrated increased viral persistence, sustained neutrophilia, and further increments in mucin gene and chemokine expression compared to other groups.

Conclusions: These findings indicate that in addition to CS, bacteria may also contribute to development of COPD, particularly changes in airways. Mice exposed to CS/HK-NTHi are also more susceptible to subsequent viral infection than mice exposed to either CS or HK-NTHi alone.

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PAS staining of lung sections. Paraffin lung sections were stained with PAS to determine goblet cell metaplasia in large and small airways. A to D, represents large airways and F to I represents small airways from mice exposed to RA, CS, HK-NTHi and CS/HK-NTHi respectively. Arrows in C, D and I represents cells positive for PAS, a marker of goblet cells. Number of PAS positive cells in large (E) and small (J) airway epithelia were counted in at least 10 random fields per slide and expressed as number of goblet cells/100 μM basement membrane length. Data represents median with range calculated from 5–6 mice (* different from RA-exposed mice, p ≤ 0.05, ANOVA on ranks; # different from CS-exposed mice, p ≤ 0.05, ANOVA on ranks; † different from HK-NTHi-exposed mice, p ≤ 0.05, ANOVA on ranks). Airway epithelial hyperplasia is observed in large airways of HK-NTHi (C) and both large (D) and small (H) airways of CS/HK-NTHi exposed mice. Images are representative of 5–6 mice per group.
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Figure 2: PAS staining of lung sections. Paraffin lung sections were stained with PAS to determine goblet cell metaplasia in large and small airways. A to D, represents large airways and F to I represents small airways from mice exposed to RA, CS, HK-NTHi and CS/HK-NTHi respectively. Arrows in C, D and I represents cells positive for PAS, a marker of goblet cells. Number of PAS positive cells in large (E) and small (J) airway epithelia were counted in at least 10 random fields per slide and expressed as number of goblet cells/100 μM basement membrane length. Data represents median with range calculated from 5–6 mice (* different from RA-exposed mice, p ≤ 0.05, ANOVA on ranks; # different from CS-exposed mice, p ≤ 0.05, ANOVA on ranks; † different from HK-NTHi-exposed mice, p ≤ 0.05, ANOVA on ranks). Airway epithelial hyperplasia is observed in large airways of HK-NTHi (C) and both large (D) and small (H) airways of CS/HK-NTHi exposed mice. Images are representative of 5–6 mice per group.

Mentions: Lung sections from mice exposed to room air (RA), RA/HK-NTHi, CS, CS-HK-NTHi were evaluated by light microscopy. RA-exposed mice showed normal morphology with baseline air space size and no appreciable inflammation (Figure 1A and1B). CS-exposed mice showed mild lung inflammation, enlarged airspaces in a patchy distribution, and accumulated inflammatory cells (possibly macrophages) in the airspaces (Figure 1C and1D). Mice exposed to HK-NTHi showed no enlarged airspaces, but demonstrated peribronchiolar inflammation (Figure 1E to1H). Mice treated with a combination of CS and HK-NTHi showed enlarged airspaces and mild lung inflammation (Figure 1I), as well as accumulation of inflammatory cells in peribronchiolar and perivascular areas (Figure 1J and1K) and in the airspaces (Figure 1L). Compared to RA- or CS-exposed mice, both HK-NTHi and CS/HK-NTHi-exposed mice showed increases in the numbers of PAS positive cells (indicative of goblet cell metaplasia) in large airway epithelia, however it was more pronounced in CS/NK-NTHi-exposed mice (Figure 2A to2D). Mice in CS/HK-NTHi group, but not animals in other groups showed increased numbers of PAS positive cells in small airway epithelia (Figure 2E to2H). Mice exposed to HK-NTHi or CS/HK-NTHi also showed airway epithelial hyperplasia in both small and large airways, but it was more prominent in CS/HK-NTHi-exposed mice.


Combined exposure to cigarette smoke and nontypeable Haemophilus influenzae drives development of a COPD phenotype in mice.

Ganesan S, Comstock AT, Kinker B, Mancuso P, Beck JM, Sajjan US - Respir. Res. (2014)

PAS staining of lung sections. Paraffin lung sections were stained with PAS to determine goblet cell metaplasia in large and small airways. A to D, represents large airways and F to I represents small airways from mice exposed to RA, CS, HK-NTHi and CS/HK-NTHi respectively. Arrows in C, D and I represents cells positive for PAS, a marker of goblet cells. Number of PAS positive cells in large (E) and small (J) airway epithelia were counted in at least 10 random fields per slide and expressed as number of goblet cells/100 μM basement membrane length. Data represents median with range calculated from 5–6 mice (* different from RA-exposed mice, p ≤ 0.05, ANOVA on ranks; # different from CS-exposed mice, p ≤ 0.05, ANOVA on ranks; † different from HK-NTHi-exposed mice, p ≤ 0.05, ANOVA on ranks). Airway epithelial hyperplasia is observed in large airways of HK-NTHi (C) and both large (D) and small (H) airways of CS/HK-NTHi exposed mice. Images are representative of 5–6 mice per group.
© Copyright Policy - open-access
Related In: Results  -  Collection

License 1 - License 2
Show All Figures
getmorefigures.php?uid=PMC3926338&req=5

Figure 2: PAS staining of lung sections. Paraffin lung sections were stained with PAS to determine goblet cell metaplasia in large and small airways. A to D, represents large airways and F to I represents small airways from mice exposed to RA, CS, HK-NTHi and CS/HK-NTHi respectively. Arrows in C, D and I represents cells positive for PAS, a marker of goblet cells. Number of PAS positive cells in large (E) and small (J) airway epithelia were counted in at least 10 random fields per slide and expressed as number of goblet cells/100 μM basement membrane length. Data represents median with range calculated from 5–6 mice (* different from RA-exposed mice, p ≤ 0.05, ANOVA on ranks; # different from CS-exposed mice, p ≤ 0.05, ANOVA on ranks; † different from HK-NTHi-exposed mice, p ≤ 0.05, ANOVA on ranks). Airway epithelial hyperplasia is observed in large airways of HK-NTHi (C) and both large (D) and small (H) airways of CS/HK-NTHi exposed mice. Images are representative of 5–6 mice per group.
Mentions: Lung sections from mice exposed to room air (RA), RA/HK-NTHi, CS, CS-HK-NTHi were evaluated by light microscopy. RA-exposed mice showed normal morphology with baseline air space size and no appreciable inflammation (Figure 1A and1B). CS-exposed mice showed mild lung inflammation, enlarged airspaces in a patchy distribution, and accumulated inflammatory cells (possibly macrophages) in the airspaces (Figure 1C and1D). Mice exposed to HK-NTHi showed no enlarged airspaces, but demonstrated peribronchiolar inflammation (Figure 1E to1H). Mice treated with a combination of CS and HK-NTHi showed enlarged airspaces and mild lung inflammation (Figure 1I), as well as accumulation of inflammatory cells in peribronchiolar and perivascular areas (Figure 1J and1K) and in the airspaces (Figure 1L). Compared to RA- or CS-exposed mice, both HK-NTHi and CS/HK-NTHi-exposed mice showed increases in the numbers of PAS positive cells (indicative of goblet cell metaplasia) in large airway epithelia, however it was more pronounced in CS/NK-NTHi-exposed mice (Figure 2A to2D). Mice in CS/HK-NTHi group, but not animals in other groups showed increased numbers of PAS positive cells in small airway epithelia (Figure 2E to2H). Mice exposed to HK-NTHi or CS/HK-NTHi also showed airway epithelial hyperplasia in both small and large airways, but it was more prominent in CS/HK-NTHi-exposed mice.

Bottom Line: CS/HK-NTHi-exposed mice also expressed increased levels of mucin genes and cytokines compared to mice in other groups.CS/HK-NTHi-exposed mice infected with RV demonstrated increased viral persistence, sustained neutrophilia, and further increments in mucin gene and chemokine expression compared to other groups.These findings indicate that in addition to CS, bacteria may also contribute to development of COPD, particularly changes in airways.

View Article: PubMed Central - HTML - PubMed

Affiliation: Department of Pediatrics and Communicable Diseases, University of Michigan, 1150 W, Medical Center Dr,, Ann Arbor, MI 48109-5688, USA. usajjan@umich.edu.

ABSTRACT

Background: Cigarette smoke (CS) is the major etiologic factor of chronic obstructive pulmonary disease (COPD). CS-exposed mice develop emphysema and mild pulmonary inflammation but no airway obstruction, which is also a prominent feature of COPD. Therefore, CS may interact with other factors, particularly respiratory infections, in the pathogenesis of airway remodeling in COPD.

Methods: C57BL/6 mice were exposed to CS for 2 h a day, 5 days a week for 8 weeks. Mice were also exposed to heat-killed non-typeable H. influenzae (HK-NTHi) on days 7 and 21. One day after the last exposure to CS, mice were sacrificed and lung inflammation and mechanics, emphysematous changes, and goblet cell metaplasia were assessed. Mice exposed to CS or HK-NTHi alone or room air served as controls. To determine the susceptibility to viral infections, we also challenged these mice with rhinovirus (RV).

Results: Unlike mice exposed to CS or HK-NTHi alone, animals exposed to CS/HK-NTHi developed emphysema, lung inflammation and goblet cell metaplasia in both large and small airways. CS/HK-NTHi-exposed mice also expressed increased levels of mucin genes and cytokines compared to mice in other groups. CS/HK-NTHi-exposed mice infected with RV demonstrated increased viral persistence, sustained neutrophilia, and further increments in mucin gene and chemokine expression compared to other groups.

Conclusions: These findings indicate that in addition to CS, bacteria may also contribute to development of COPD, particularly changes in airways. Mice exposed to CS/HK-NTHi are also more susceptible to subsequent viral infection than mice exposed to either CS or HK-NTHi alone.

Show MeSH
Related in: MedlinePlus