Bronchiolar epithelial catalase is diminished in smokers with mild COPD.

This study aimed to investigate bronchiolar catalase expression and its relationship with smoking and/or chronic obstructive pulmonary disease (COPD) in humans and to determine the dynamic change of bronchiolar catalase expression in response to cigarette smoke in mice. Lung tissue was obtained from 36 subjects undergoing surgery for peripheral tumours, consisting of life-long nonsmokers and smokers with or without COPD. Male C57BL/6 mice were subjected to cigarette smoke exposure for up to 3 months followed by a 28-day cessation period. We quantified bronchiolar catalase mRNA using laser capture microdissection and quantitative reverse transcription-polymerase chain reaction. C22 club cells (Clara cells) in culture were exposed to cigarette smoke extract and monitored for viability when catalase expression was decreased by siRNA. Catalase was decreased at mRNA and protein levels in bronchiolar epithelium in smokers with COPD. In mice, bronchiolar catalase is temporarily upregulated at 1 day after cigarette smoke exposure but is downregulated by repeated cigarette smoke exposure, and is not restored long after withdrawal once emphysema is developed. Decreasing catalase expression in C22 cells resulted in greater cigarette smoke extract-induced cell death. Bronchiolar catalase reduction is associated with COPD. Regulation of catalase depends on the duration of cigarette smoke exposure, and plays a critical role for protection against cigarette smoke-induced cell damage.

The role of catalase in pulmonary fibrosis.

BACKGROUND: Catalase is preferentially expressed in bronchiolar and alveolar epithelial cells, and acts as an endogenous antioxidant enzyme in normal lungs. We thus postulated epithelial damage would be associated with a functional deficiency of catalase during the development of lung fibrosis. METHODS: The present study evaluates the expression of catalase mRNA and protein in human interstitial pneumonias and in mouse bleomycin-induced lung injury. We examined the degree of bleomycin-induced inflammation and fibrosis in the mice with lowered catalase activity. RESULTS: In humans, catalase was decreased at the levels of activity, protein content and mRNA expression in fibrotic lungs (n = 12) compared to control lungs (n = 10). Immunohistochemistry revealed a decrease in catalase in bronchiolar epithelium and abnormal re-epithelialization in fibrotic areas. In C57BL/6J mice, catalase activity was suppressed along with downregulation of catalase mRNA in whole lung homogenates after bleomycin administration. In acatalasemic mice, neutrophilic inflammation was prolonged until 14 days, and there was a higher degree of lung fibrosis in association with a higher level of transforming growth factor-ß expression and total collagen content following bleomycin treatment compared to wild-type mice. CONCLUSIONS: Taken together, these findings demonstrate diminished catalase expression and activity in human pulmonary fibrosis and suggest the protective role of catalase against bleomycin-induced inflammation and subsequent fibrosis.

High levels of extracellular matrix metalloproteinase inducer are expressed in lymphangioleiomyomatosis.

Pulmonary lymphangioleiomyomatosis is pathologically characterized by the proliferation of abnormal smooth muscle-like cells (lymphangioleiomyomatosis cells) that synthesize excess matrix metalloproteinases. Extracellular matrix metalloproteinase inducer is minimally expressed in the healthy lung, but is up-regulated in various lung injuries that are apparently associated with matrix metalloproteinases. We therefore immunohistochemically stained extracellular matrix metalloproteinase inducer in lymphangioleiomyomatosis cells and measured extracellular matrix metalloproteinase inducer in bronchoalveolar lavage fluid using an enzyme-linked immunosorbent assay. We also quantified extracellular matrix metalloproteinase inducer messenger RNA expression in the lung using quantitative reverse transcriptase-polymerase chain reaction. Intense staining for extracellular matrix metalloproteinase inducer in lymphangioleiomyomatosis cells indicated high immunoreactivity. Dual immunofluorescence studies revealed diffuse colocalization between extracellular matrix metalloproteinase inducer and alpha smooth muscle actin, matrix metalloproteinase-2, or matrix metalloproteinase-9. Although levels of extracellular matrix metalloproteinase inducer messenger RNA did not differ in whole lung homogenates from patients with lymphangioleiomyomatosis and healthy controls (1.7 +/- 0.1 versus 1.5 +/- 0.2 SE, not significant; both n = 4), lymphangioleiomyomatosis nodules retrieved by laser capture microdissection expressed 5.1 (+/-1.0 SE)-fold higher levels of extracellular matrix metalloproteinase inducer messenger RNA than lung homogenates (P = .0077, n = 4). Levels of extracellular matrix metalloproteinase inducer were significantly elevated in bronchoalveolar lavage fluid from lymphangioleiomyomatosis patients compared with controls (82.7 +/- 19.5 versus 38.6 +/- 9.0 SE pg/mL, P = .0497; n = 8 and 9, respectively). Increased levels of extracellular matrix metalloproteinase inducer colocalized with increased matrix metalloproteinases in lymphangioleiomyomatosis cells indicate that it potentially functions in pulmonary lymphangioleiomyomatosis.

Evaluation of transcutaneous CO2 responses following acute changes in PaCO2 in healthy subjects.

BACKGROUND AND OBJECTIVE: Transcutaneous blood gas-monitoring systems with miniaturized SpO(2) (peripheral blood oxygen saturation)/PCO(2) combined sensors (TOSCATM) have been widely used. There are no reports of the inter- and intra-individual variability in transcutaneous measurements of PaCO(2) (PtcCO(2)) in response to acute progressive changes in PaCO(2). This study examined inter- and intra-individual variability of PtcCO(2) measurements under semi-steady-state conditions, and characterized the behaviour of PtcCO(2) in response to acute progressive changes in PaCO(2). METHODS: Subjects breathed mixed gases through a mouthpiece connected to an automatic arterial blood gas controller. Using end-tidal PCO(2) and PO(2) as guides, PaCO(2) was controlled to increase and/or decrease between baseline and > or = 60 mm Hg, in a stepwise (n = 9) or progressive fashion (n = 6). Arterial blood was sampled when needed. RESULTS: Intra-individual correlation coefficients between PtcCO(2) and PaCO(2) were excellent in all subjects (0.971-0.989); however, the slope of the regression line varied among subjects (1.040-1.335). Bias and limits of agreement (+/- 2 SD from bias) between PtcCO(2) and PaCO(2) were -1.8 mm Hg and -7.7 to 4.1 mm Hg. Changes in PtcCO(2) in response to acute progressive changes in PaCO(2) also varied among subjects. CONCLUSION: The PtcCO(2) measurement system allows reliable estimation of PaCO(2) in a given subject. However, caution is needed when comparing absolute values between subjects or when acute changes in PaCO(2) occur.

Curcumin attenuates elastase- and cigarette smoke-induced pulmonary emphysema in mice.

Curcumin, a yellow pigment obtained from turmeric (Curcumina longa), is a dietary polyphenol that has been reported to possess anti-inflammatory and antioxidant properties. The effect of curcumin against the development of pulmonary emphysema in animal models is unknown. The aim of this study was to determine whether curcumin is able to attenuate the development of pulmonary emphysema in mice. Nine-week-old male C57BL/6J mice were treated with intratracheal porcine pancreatic elastase (PPE) or exposed to mainstream cigarette smoke (CS) (60 min/day for 10 consecutive days or 5 days/wk for 12 wk) to induce pulmonary inflammation and emphysema. Curcumin (100 mg/kg) or vehicle was administrated daily by oral gavage 1 h and 24 h before intratracheal PPE treatment and daily thereafter throughout a 21-day period in PPE-exposed mice and 1 h before each CS exposure in CS-exposed mice. As a result, curcumin treatment significantly inhibited PPE-induced increase of neutrophils in bronchoalveolar lavage fluid at 6 h and on day 1 after PPE administration, with an increase in antioxidant gene expression at 6 h and significantly attenuated PPE-induced air space enlargement on day 21. It was also found that curcumin treatment significantly inhibited CS-induced increase of neutrophils and macrophages in bronchoalveolar lavage fluid after 10 consecutive days of CS exposure and significantly attenuated CS-induced air space enlargement after 12 wk of CS exposure. In conclusion, oral curcumin administration attenuated PPE- and CS-induced pulmonary inflammation and emphysema in mice.

Matrix metalloproteinases in blood from patients with LAM.

Pulmonary lymphangioleiomyomatosis (LAM) is characterized by the proliferation of abnormal smooth muscle cells (LAM cells) and destruction of alveolar structure. Immunohistochemical studies suggest that excess matrix metalloproteinases (MMPs) synthesized by LAM cells function in the proteolytic mechanisms of this disease. We postulated MMP levels in the blood are elevated in LAM patients. Serum samples were collected from 36 LAM patients and 25 controls, and gelatinolytic activities were semi-quantified by gelatin zymography. The reliability of serum data for MMP-9 was confirmed by the measurement of MMP-9 concentration in plasma by enzyme-linked immunosorbent assay as well as by gelatin zymography. Serum levels of MMP-9 (0.7+/-0.1 AU), but not MMP-2, were significantly elevated in LAM patients compared with controls (0.1+/-0 AU). Plasma and serum levels of MMP-9 significantly correlated. These results suggest the involvement of MMP-9 in LAM.

Role of basement membrane in EMMPRIN/CD147 induction in rat tracheal epithelial cells.

Extracellular matrix metalloproteinase inducer (EMMPRIN) is a glycosylated transmembrane protein known to induce matrix metalloproteinases (MMPs). Although the expression of EMMPRIN is physiologically limited to fetal lung epithelium, the transcriptional regulation of this protein remains to be elucidated. We hypothesized that the interaction of epithelial cells with the basement membrane regulates EMMPRIN expression. The basement membrane has highly integrated architecture composed of specific extracellular matrix, such as laminins and type IV collagen, and exhibits multiple functions. We previously developed a structured basement membrane mimic, a synthesized basement membrane (sBM) substratum, in which laminin-111, a unique component of embryonic lungs, is incorporated. In the present study we quantified expression of EMMPRIN mRNA of rat tracheal epithelial cells cultured on sBM, laminin-111, type IV collagen, or laminin-332. EMMPRIN was upregulated on sBM and laminin-111, although this was not accompanied by MMP-9 induction. In contrast, type IV collagen and laminin-332 did not induce EMMPRIN. These findings suggest potential roles for basement membrane in the transcriptional regulation of tracheal epithelial EMMPRIN.

Loss of caveolin-1 in bronchiolization in lung fibrosis.

Bronchiolization is a key process in fibrosing lung in which the proliferative status of bronchiolar epithelium changes, leading to abnormal epithelial morphology. Within the context that caveolin-1 acts to suppress epithelial proliferation, we postulated that stimulating epithelial injury would lead to caveolin-1 downregulation and encourage proliferation. The present study evaluates the expression of caveolin-1, especially in bronchiolization, in C57BL/6J mice with bleomycin-induced lung fibrosis and in various types of re-epithelialization in human interstitial pneumonias (IPs). Immunohistochemically, levels of caveolin-1 decreased in the bronchiolar epithelium of mice treated with bleomycin. Levels of caveolin-1 mRNA in the whole lung were decreased at 7 and 14 days. Caveolin-1 mRNA was also decreased in laser-capture microdissection- retrieved bronchiolar epithelial cells at 7 days. Among patients with 12 IPs, including four usual IPs (UIPs) and eight nonspecific IPs (NSIPs), whole lung caveolin-1 was significantly decreased compared with 12 controls at both mRNA and protein levels. By scoring immunointensity, caveolin-1 was significantly reduced in bronchiolization and squamous metaplasia as well as in bronchiolar epithelium in 23 IPs (12 UIPs and 11 NSIPs) compared with bronchiolar epithelium from seven controls. These data suggested that loss of caveolin-1 is associated with abnormal re-epithelialization in lung fibrosis.

Extracellular matrix metalloproteinase inducer in interstitial pneumonias.

Extracellular matrix metalloproteinase inducer (EMMPRIN), a glycosylated transmembrane protein that induces matrix metalloproteinases (MMPs), is minimally expressed in the normal adult lung. We previously reported that it is up-regulated in murine bleomycin-induced lung injury. In this study, we determined the expression of EMMPRIN and its association with MMP-2, MMP-7, and MMP-9 in interstitial pneumonias (IPs). We performed immunohistochemistry for EMMPRIN and MMPs on lung tissue from 22 subjects with various IPs. We did bronchoalveolar lavage (BAL) on 9 of these subjects and 13 others with IPs to measure the soluble EMMPRIN in BAL fluid. For comparison, immunohistochemistry or BAL was done on 14 subjects without IPs. The staining intensity for each protein was scored from 0 to 3 in various epithelial cell types. Soluble EMMPRIN in BAL fluid was measured by an enzyme-linked immunosorbent assay. Extracellular matrix metalloproteinase inducer was prominent in abnormal epithelial cells. It was more prominent in hyperplastic type II cells, compared with epithelium in alveolar bronchiolization. It was also elevated in BAL fluid from the subjects with IPs. Matrix metalloproteinases were expressed in cells expressing EMMPRIN, although the profile of MMPs varied among the different abnormal epithelial cell types with MMP-2 and MMP-7 in hyperplastic type II cells and MMP-7 and MMP-9 in cells showing squamous metaplasia and cells comprising bronchiolization. These results suggest a role of EMMPRIN in reepithelialization in IPs.