Overview of the Pathology of Pulmonary Emphysema in the Human

A ferret model of COPD-related chronic bronchitis

Chronic obstructive pulmonary disease (COPD) is the third leading cause of death in the US. The majority of COPD patients have symptoms of chronic bronchitis, which lacks specific therapies. A major impediment to therapeutic development has been the absence of animal models that recapitulate key clinical and pathologic features of human disease. Ferrets are well suited for the investigation of the significance of respiratory diseases, given prior data indicating similarities to human airway physiology and submucosal gland distribution. Here, we exposed ferrets to chronic cigarette smoke and found them to approximate complex clinical features of human COPD. Unlike mice, which develop solely emphysema, smoke-exposed ferrets exhibited markedly higher numbers of early-morning spontaneous coughs and sporadic infectious exacerbations as well as a higher level of airway obstruction accompanied by goblet cell metaplasia/hyperplasia and increased mucus expression in small airways, indicative of chronic bronchitis and bronchiolitis. Overall, we demonstrate the first COPD animal model exhibiting clinical and pathologic features of chronic bronchitis to our knowledge, providing a key advance that will greatly facilitate the preclinical development of novel treatments for this disease.

HRCT and histopathological evaluation of fibrosis and tissue destruction in IPF associated with pulmonary emphysema

Idiopathic pulmonary fibrosis has been associated with emphysema in cigarette smokers as a new clinical entity: combined pulmonary fibrosis and emphysema (CPFE). In order to compare histomorphometrical, roentgenological and immunohistochemical aspects of usual interstitial pneumonia (UIP) with and without associated pulmonary emphysema, 17 patients with biopsy-proven UIP were evaluated. Morphometrical evaluation of lung parenchyma destruction was used to divide patients in two subgroups: emphysema/UIP (n=9) and UIP alone (n=8); four patients with biopsy-proven emphysema without fibrosis were also evaluated. At HRTC scan, emphysematous lesions were prevalent in the upper fields of both emphysema/UIP and emphysema groups and the distribution of fibrotic lesions was similar in emphysema/UIP compared to UIP alone. The semiquantitative histopathological fibrotic score was also similar in emphysema/UIP and UIP alone. In addition, the expression of tumor necrosis factor (TNF)-alpha, matrix metalloproteinase (MMP)-2, MMP-9, MMP-7 and membrane type 1-metalloproteinase (MT1-MMP) by fibroblasts of myofibroblastic foci was similar in emphysema/UIP and UIP alone patients. In contrast, fibroblasts in areas of parenchymal destruction of emphysema/UIP expressed MMP-2, MMP-9, MMP-7 and MT1-MMP at variable but significantly higher levels when compared to emphysema subjects, in the presence of similar levels of TIMP-1, TIMP-2 and TNF-alpha. Fibrotic and emphysematous lesions in emphysema/UIP patients appear to follow the roentgenological and histopathological patterns expected for either UIP or emphysema. Interstitial fibroblast activation is more pronounced in the areas of lung destruction in emphysema/UIP compared to those with emphysema alone, as for exaggerated tissue remodeling.

Expression and secretion of CXCL-8 and CXCL-10 from mycobacterium bovis BCG-infected human epithelial cells: role of IL-4

CXC chemokine release can be modulated by Th2-derived cytokines. Interleukin(IL)-4 is one of the cytokines that are the hallmark of the Th-2 response, and plays an important role in human tuberculosis. In the current study, we investigated the effect of IL-4 on chemokine production by human epithelial cells infected with Mycobacterium bovis bacillus calmette-guérin (BCG). Gene expression of CXCL-8 and CXCL-10 was determined by the reverse transcription (RT)-polymerase chain reaction method. The levels of immunoreactive CXCL-8 and CXCL-10 were determined by enzyme-linked immunosorbent assay. We found that, although M. bovis BCG induced gene expression of CXCL-8 and CXCL-10 in M. bovis BCG-infected human epithelial cells, CXCL-8 mRNA level was significantly reduced by IL-4, whereas no significant effect of IL-4 was observed on CXCL10 mRNA level. In addition, IL-4 decreased CXCL-8 (in a graded and significant manner) but not CXCL-10 secretion. These results were further confirmed, since a significant reversion was obtained with a neutralizing antibody to human IL-4, whereas an isotype-matched control antibody had no significant effect on CXCL-8 secretion. Furthermore, we found a similar effect of IL-4 on M. bovis BCG-induced CXCL-8 and CXCL-10 secretion by using other human epithelial A549 cell line. Collectively, these data demonstrate that M. bovis BCG-infected human epithelial cells can have an active role in a local inflammatory immune response via the secretion of CXC chemokines which can be selectively regulated by Th2-derived cytokines.

Mycobacterium bovis BCG induces CXC chemokine ligand 8 secretion via the MEK-dependent signal pathway in human epithelial cells

Current knowledge of the cellular signaling by Mycobacterium bovis bacillus Calmette-Guerin (BCG) in epithelial cells is still limited. In this study, we provide evidence that the signaling events induced by M. bovis BCG in these cells included phosphorylation of extracellular signal-regulated kinase (ERK) and p38 mitogen-activated protein kinase (MAPK). Our data also demonstrate that M. bovis BCG-induced CXC chemokine ligand (CXCL)8 release in epithelial cells was reduced by a mitogen-activated protein/ERK kinase (MEK) inhibitor (PD98059), but not by a p38 MAPK (SB203580) inhibitor. In addition, we found that a second and more potent MEK inhibitor (U0126) significantly blocked CXCL8 release in epithelial cells by M. bovis BCG. Evaluation of CXCL8 RNA messages by reverse transcription-polymerase chain reaction (RT-PCR) revealed that the inhibitory effect of PD98059 and U0126 was associated with a reduction in this parameter. Moreover, the induction of CXCL8 secretion in epithelial cells by M. bovis BCG occurs at the transcription level. Collectively, the findings reported in the present study suggest that MEK signaling is essential for the induction of CXCL8 in epithelial cells in response to M. bovis BCG.

Hyperpolarized helium-3 MR imaging of pulmonary function

Recent advances in HP MR imaging contrast agents have led to novel tests of pulmonary function. Many of these tests show promise in the clinical arena.

Emphysema and metalloelastase expression in mouse lung induced by cigarette smoke

Cigarette smoke (CS) causes pulmonary emphysema in humans and elastin degradation plays a key role in its pathogenesis. Previous studies on CS-exposed animals have been equivocal and have not clearly demonstrated the progression of the disease. In this study, morphometry was used to assess lung modifications to alveolar septa, airspaces, elastic and collagen fibers, and alveolar macrophages. Male (n = 40) C57/BL6 mice were exposed 3 times/day, whole body, to CS from three cigarettes for 10, 20, 30, or 60 days. Control groups (n = 10) were sham-smoked or received no exposure (day 0, n = 10). Morphometry included measurements of volume fraction of alveolar septa and airspaces, elastic and collagen fibers, and surface fraction of elastic fibers and alveolar septa. Morphometrical differences in mice after 60 days of exposure were greater than those after 10, 20, or 30 days, suggesting a progression of the disease. Inflammatory lesions in the lungs of mice contained significantly more metalloelastase (MMP-12) in macrophages at 10, 20, and 30 days than in controls of mice exposed for 60 days. These results suggest that elastin degradation took place during development of pulmonary changes in mice exposed to CS, and activation of MMPs specific for elastin may be a determining factor for susceptibility to emphysema.