Matrix metalloproteinases (MMPs) are zinc-endopeptidases responsible for degradation of the extracellular matrix (ECM) components including basement membrane collagen, interstitial collagen, fibronectin, and various proteoglycans, during normal remodeling and repair processes. The turnover and remodeling of ECM must be tightly regulated since excessive or inappropriate expression of MMPs may contribute to the pathogenesis of tissue destructive processes associated with lung inflammation and disease. Despite the fact that our knowledge in the field of MMP biology is rapidly expanding, the role of MMPs in the pathogenesis of lung diseases is still not clear. The aim of the present review is to present the basic principles of MMP biology and, subsequently, to focus on the clinical and experimental evidence related to MMP activity in various lung disorders, including lung cancer, pleural effusions, chronic obstructive pulmonary disease, asthma, acute respiratory distress syndrome and interstitial lung diseases.

COPD is a diverse disease entity with multiple dimensions that uniquely define the patient's performance, morbidity and mortality. FEV(1) is both the traditional metric used to define the progression of COPD as well as the strongest spirometric predictor of mortality in COPD patients. However, besides pulmonary functional abnormalities, COPD is also associated with significant systemic effects. Therefore, the global assessment of an affected patient should include different aspects of the consequences of this disorder, beyond the "gold-standard" assessment of airflow limitation. Quantification of the patient's dyspnea, body composition as expressed by BMI, simple measures of exercise capacity such as the 6MWD, assessment of comorbidities and identification of characteristics related to different phenotypes are features that may lead to more optimal management of such patients.

The pathways underlying chronic obstructive pulmonary disease exacerbations (ECOPD) remain unclear. This study describes the clinical, functional and biochemical changes during recovery from ECOPD. Thirty hospitalized patients with Anthonisen's type-I ECOPD were evaluated on days 0 (admission), 3, 10 and 40. A five-symptom score (TSS), performance status and quality of life were evaluated. Post-bronchodilator spirometry, blood gases, oxidative stress, C-reactive protein (CRP), serum amyloid-A (SAA), tumor necrosis factor-alpha (TNF-alpha), interleukin-6 (IL-6) and fibrinogen were also measured. Patients were classified as early- or late-recoverers, based on whether dyspnea had returned to pre-exacerbation level by day 10. Most clinical, functional and biochemical parameters improved during follow-up. CRP and IL-6 levels reduced on Day 3 (p<0.05), whereas SAA on Day 10 (p<0.01). TNF-alpha was reduced on Days 3 and 10, but on Day 40 its levels returned to baseline. Fibrinogen and WBC reduced only by day 40. TSS and dyspnea were correlated inversely with FEV(1) on days 3, 10 and 40. Although late-recoverers had lower FEV(1) on admission, none of the reported measurements on admission and day 3 predicted early recovery. During recovery from ECOPD, symptomatic improvement correlates only with post-bronchodilator FEV(1) whereas systemic inflammatory burden subsidence does not correlate with clinical and functional changes. Although late-recoverers have lower FEV(1) on admission, none of the measured parameters is able to predict early symptomatic recovery.

The aim of the present study was to evaluate the levels of VEGF, 8-isoprostane and TNF-alpha in EBC and serum of patients with primary lung cancer prior to the initiation of any treatment, in order to evaluate their possible diagnostic role. Furthermore, associations between VEGF, 8-isoprostane and TNF-alpha levels in EBC and serum with clinicopathologic factors were investigated. We enrolled 30 patients with lung cancer (mean age 65.2+/-10.5 years) and 15 age and gender-matched healthy smokers as controls. Serum and EBC were collected before any treatment. TNF-alpha, VEGF and 8-isoprostane levels in EBC and serum were analyzed by an immunoenzymatic method (ELISA). A statistically significant difference was observed between lung cancer patients and the control group regarding the values of TNF-alpha, both in EBC (52.9+/-5.0 pg/ml vs. 19.4+/-3.9 pg/ml, p<0.0001) and serum (44.5+/-6.3 pg/ml vs. 22.2+/-4.3 pg/ml, p=0.035). Moreover, EBC VEGF levels were higher in patients with T3-T4 tumor stage compared to T1-T2 (9.3+/-2.8 pg/ml vs. 2.3+/-0.7pg/ml, p=0.047). A statistically significant correlation was also observed between serum and EBC values of VEGF (r=0.52, p=0.019). In addition, serum levels of VEGF were higher in lung cancer patients than in controls (369.3+/-55.1 pg/ml vs. 180.5+/-14.7 pg/ml, p=0.046). VEGF serum levels were also found higher in patients with advanced stage of disease (IIIB-IV) and distant nodal metastasis (N2-N3). No differences were observed in 8-isoprostane in EBC between lung cancer patients and controls. In contrast, serum 8-isoprostane levels were higher in lung cancer patients compared to controls (24.9+/-3.6 pg/ml vs. 12.9+/-1.6 pg/ml, p=0.027) and were higher in patients with advanced disease. All three biomarkers presented acceptable reproducibility in the EBC on two consecutive days. In conclusion, we have shown that TNF-alpha, VEGF and 8-isoprostane are elevated in the serum of lung cancer patients and increased serum VEGF and 8-isoprostane levels are related to advanced disease. In EBC, increased TNF-alpha levels were observed in lung cancer patients, whereas increased VEGF levels were observed in advanced T-stage. Further longitudinal studies are warranted for the evaluation of the prognostic role of these biomarkers in lung cancer.

Cold air hyperventilation is an indirect challenge (cold air challenge, CACh) with high specificity and low sensitivity in defining asthmatic subjects. A small proportion of chronic obstructive pulmonary disease (COPD) patients present with positive CACh. The aim of this prospective study was to investigate the presence of factors related to cold air challenge (CACh) in COPD patients. Factors examined were FEV(1), FEV(1)/FVC, reversibility after bronchodilation, eosinophils in induced sputum, bronchial hyperresponsiveness to methacholine and the spirometric response to tiotropium compared to placebo. We studied 92 consecutive COPD patients in order to retrieve 15 CACh positive + patients. Fifteen COPD patients with negative CACh [CACh(-)], randomly selected from the initial group, were added in order to retrieve a group of 30 patients. Spearman's correlation coefficient was used in order to evaluate possible significant correlations between CACh values and study parameters. Sixteen percent of our subjects presented CACh+. CACh values were repeatable with an intraclass correlation coefficient between the two measurements 0.980 (95% CI 0.940-0.993). The only significant correlation observed was between Delta FEV(1) after CACh [Delta(C)FEV(1)] and trough FEV(1) values post tiotropium inhalation (r(2) = 0.62, p < 0.0001). When we analyzed the response to tiotropium in the 2 separate groups we found that patients with CACh+ presented significantly lower values of trough FEV(1) compared to those with CACh(-). In conclusion, a small proportion of COPD patients present with bronchial hyperresponsiveness to CACh. The only parameter related to CACh + in our study was a smaller bronchodilating effect of tiotropium.

Exhaled breath condensate (EBC) analysis, a rather appealing and promising method, can be used to evaluate conveniently and non-invasively a wide range of molecules from the respiratory tract, and to understand better the pathways propagating airway inflammation. A large number of mediators of inflammation, including adenosine, ammonia, hydrogen peroxide, isoprostanes, leukotrienes, prostanoids, nitrogen oxides, peptides and cytokines, have been studied in EBC. Concentrations of such mediators have been shown to be related to the underlying asthma and its severity and to be modulated by therapeutic interventions. Despite the encouraging positive results to date, the introduction of EBC in everyday clinical practice requires the resolution of some methodological pitfalls, the standardization of EBC collection and finally the identification of a reliable biomarker that is reproducible has normal values and provides information regarding the underlying inflammatory process and the response to treatment. So far, none of the parameters studied in EBC fulfils the aforementioned requirements with one possible exception: pH. EBC pH is reproducible, has normal values, reflects a significant part of asthma pathophysiology and is measurable on-site with standardized methodology although some methodological aspects of measurement of pH in EBC (e.g. the effect of ambient CO(2), sample de-aeration, time for pH measurement) require further research. However, EBC pH has not been evaluated prospectively as a guide for treatment, in a manner similar to exhaled NO and sputum eosinophils. EBC represents a simple and totally non-invasive procedure that may contribute towards our understanding of asthma pathophysiology. Besides the evaluation of new biomarkers, the standardization of the already existing procedures is warranted for the introduction of EBC in clinical practice.

The need for non-invasive assessment of airway inflammation is imperative, since inflammatory airway diseases, such as asthma and COPD, are characterized by variation in their clinical presentation throughout their course. Exhaled breath condensate (EBC) collection represents a rather appealing method that can be used to conveniently and noninvasively collect a wide range of volatile and non-volatile molecules from the respiratory tract, without affecting airway function or inflammation. Although promising, EBC is currently used only as a research tool, due to the lack of appropriate standardization and the absence of reference values. The large number of measurable biomarkers and the diversity of the used methodologies are some of the points that hamper its wide clinical application. This review focuses mainly on the presentation of normal values of the most widely studied EBC markers as reported by investigators that have used healthy subjects as controls or as a basic study population. These biomarkers include hydrogen peroxide, NO-related products, arachidonic acid metabolites and pH. From those biomarkers, the only one with established reference values in healthy subjects is EBC pH, whereas the majority of the rest need further refinement and standardization of the methodologies used. Different subpopulations and the effect of various factors on healthy subjects are also reported, in an effort to delineate future directions that may lead to the establishment of reference values.

The data on long-term application of non-invasive ventilation (NIV) in patients with chronic respiratory failure due to COPD are contradictory. We evaluated the effect of the addition of NIV to optimal treatment for 1 year on the quality of life of stable hypercapnic COPD patients. NIV was offered to 49 of 58 initially enrolled consecutive patients, of whom 22 refused NIV and comprised the standard treatment group whereas 27 received NIV. Quality of life was assessed with the SF-36 questionnaire. Additional measurements included blood gases, pulmonary function tests, dyspnea, daytime sleepiness, exacerbations and hospitalizations. The NIV group showed a significant improvement in quality of life in the third month, both in the Physical (31+/-4 to 38+/-8, p<0.0001) and the Mental Component Summary Score (28+/-7 to 40+/-10, p=0.009), that was maintained until the twelfth month. PaCO2 decreased by the first month in the NIV group (54+/-4.5 to 44.6+/-5.6 mmHg, p<0.0001), and PaO2 rose during the sixth month (58.9+/-5.7 to 64.4+/-6.5 mmHg, p=0.004). Dyspnea and diurnal sleepiness improved significantly. No significant improvements were observed in the control group. Patients on NIV spent less days in the hospital compared to controls. NIV when added to optimal medical treatment has beneficial effects on quality of life in stable hypercapnic COPD patients, with additional improvements in arterial blood gases, dyspnea and daytime sleepiness.

Vascular endothelial growth factor (VEGF) is known to play crucial role in tumour angiogenesis. It is demonstrated that VEGF can be up-regulated by oxidative stress. The aim of this study was to determine the serum VEGF levels and oxidative stress in patients with primary lung cancer and to investigate their association with clinicopathologic factors. We measured serum VEGF levels and oxidative stress in 63 patients (age 63.02+/-1.12 S.E.M.) with primary lung cancer before any treatment (39 NSCLC and 24 SCLC; 6 patients stage I, 3 stage II, 25 stage III and 29 stage IV) and 25 normal subjects. The serum VEGF levels were measured with enzyme linked immunosorbent assay. Serum oxidative stress levels were detected by a commercially available assay (D-ROMs test, Diacron, Grossetto, Italy). The levels of oxidative stress in patients were higher than those in normal subjects (555.3+/-30.35 UCarr vs. 360.1+/-17.46 UCarr). Additionally, a significant difference was found in serum VEGF levels between lung cancer patients and healthy control subjects (428.1+/-38.42pg/ml vs. 298.8+/-19.89pg/ml, respectively, p=0.040). Interestingly, serum oxidative stress presented a significant correlation with serum VEGF levels in patients with lung cancer (r=0.542, p=0.002). Serum VEGF levels were significantly associated with the clinical staging (N-stage) of the patients (p=0.023), performance status (p=0.004) and age (p=0.004). In conclusion, oxidative stress and VEGF are significantly increased in patients with primary lung cancer. The correlation between them might implicate new aspects of the mechanisms controlling tumour angiogenesis and may present clinical interest in the future. Further studies are warranted to evaluate the role of oxidative stress and VEGF as possible biomarkers for the diagnosis and follow-up of patients with lung cancer.

Previous work suggests that exercise-induced arterial hypoxaemia (EIAH), causing only moderate arterial oxygen desaturation (SaO2 : 92 +/- 1%), does not exaggerate diaphragmatic fatigue exhibited by highly trained endurance athletes. Since changes in arterial O2 tension have a significant effect on the rate of development of locomotor muscle fatigue during strenuous exercise, the present study investigated whether hypoxia superimposed on EIAH exacerbates the exercise-induced diaphragmatic fatigue in these athletes. Eight trained cyclists (VO2max : 67.0 +/- 2.6 ml kg(-1) min(-1); mean +/- S.E.M.) completed in balanced order four 5 min exercise tests leading to different levels of end-exercise SaO2 (64 +/- 2, 83 +/- 1, 91 +/- 1 and 96 +/- 1%) via variations in inspired O2 fraction (FiO2 : 0.13, 0.17, 0.21 and 0.26, respectively). Measurements were made at corresponding intensities (65 +/- 3, 80 +/- 3, 85 +/- 3 and 90 +/- 3% of normoxic maximal work rate, respectively) in order to produce the same tidal volume, breathing frequency and respiratory muscle load at each FiO2. The mean pressure time product of the diaphragm did not differ across the four exercise tests and ranged between 312 +/- 28 and 382 +/- 22 cmH2O s min(-1). Ten minutes into recovery, twitch transdiaphragmatic pressure (P(di,tw)) determined by bilateral phrenic nerve stimulation, was significantly (P = 0.0001) reduced after all tests. After both hypoxic tests (FiO2 : 0.13, 0.17) the degree of fall in P(di,tw) (by 26.9 +/- 2.7 and 27.4 +/- 2.6%, respectively) was significantly greater (P < 0.05) than after the normoxic test (by 20.1 +/- 3.4%). The greater amount of diaphragmatic fatigue in hypoxia at lower leg work rates (presumably requiring smaller leg blood flow compared with normoxia at higher leg work rates), suggests that when ventilatory muscle load is similar between normoxia and hypoxia, hypoxia exaggerates diaphragmatic fatigue in spite of potentially greater respiratory muscle blood flow availability.