Respiratory mechanics do not always mirror pulmonary histological changes in emphysema.
OBJECTIVE
To verify the accordance of functional and morphometric parameters during the development of emphysema.


METHODS
BALB/c mice received a nasal drop of either papain or saline solution and were studied after 1, 3, 15, 28, and 40 days. Functional parameters, such as airway resistance, tissue damping, and tissue elastance, were analyzed. To evaluate the structural changes and possible mechanisms involved in this disease, we measured the mean linear intercept, the volume proportions of elastic and collagen fibers, the number of macrophages, the numbers of cells expressing metalloprotease 12 and 8-isoprostane in lung parenchyma.


RESULTS
We only observed decreases in tissue elastance and tissue damping on the 28th day, with a concomitant increase in the mean linear intercept, indicating the presence of emphysema. However, only the mean linear intercept values remained increased until the 40th day. The volume proportion of collagen fibers was increased from the 15th day to the 40th day, whereas the volume proportion of elastic fibers was only increased on the 40th day. The number of macrophages increased beginning on the 1st day. The expression of metalloproteinase 12 was increased from the 3rd day until the 40th day. However, 8-isoprostane expression was only increased on the 1st and 3rd days.


CONCLUSIONS
In this study, morphometric parameters were found to be more reliable for detecting the presence of emphysema than the functional parameters measured by respiratory mechanics. Further investigations are necessary to understand how the extracellular matrix remodeling observed in the lung parenchyma could be involved in this process.
Departamento de Clínica Médica, Faculdade de Medicina, Universidade de São Paulo, São Paulo, Brazil. adriana@ig.com.br
Adriana Martins
AM
Anciães
Clarice Rosa
CR
Olivo
Carla Máximo
CM
Prado
Keila H
KH
Kagohara
Tatiana da Silva
Tda S
Pinto
Henrique T
HT
Moriya
Thais
T
Mauad
Mílton de Arruda
Mde A
Martins
Fernanda Degobbi Tenorio Quirino dos Santos
FD
Lopes
D000818:Animals; D003094:Collagen / Q000378:metabolism; D004195:Disease Models, Animal; D018450:Disease Progression; D004547:Elastic Tissue / Q000378:metabolism; D007150:Immunohistochemistry; D008168:Lung / Q000473:pathology / Q000503:physiopathology; D008264:Macrophages / Q000378:metabolism; D008297:Male; D053508:Matrix Metalloproteinase 12 / Q000378:metabolism; D051379:Mice; D008807:Mice, Inbred BALB C; D010206:Papain; D011656:Pulmonary Emphysema / Q000139:chemically induced / Q000473:pathology* / Q000503:physiopathology*; D015656:Respiratory Mechanics / Q000502:physiology*; D013997:Time Factors
D003094:Collagen; D010206:Papain; D053508:Matrix Metalloproteinase 12