Thermolysin-like serum metalloendopeptidase. A new marker for active sarcoidosis that complements serum angiotensin-converting enzyme

Acute changes in sputum collected from exposed human subjects in mining conditions

Neprilysin (NEP) is a key cell surface peptidase in the maintenance of airway homeostasis and the development of pulmonary disorders. However, little information is available about the effect of particulate matter (PM) on airway NEP. In this controlled human exposure study, changes in induced sputum were measured in 11 subjects at baseline, overshot (OS) mucking, and diesel exhaust (DE) exposure days. Neither OS condition nor DE exposure was found to induce significant changes in total protein, but DE induced significant increases in cell numbers of macrophages and epithelium. Moreover, significant increases in soluble NEP were observed following OS mining dust particulates (0.43 +/- 0.06 nmol/microg protein/min; p = .023) and DE exposure (0.40 +/- 0.03 nmol/microg protein/min; p = .035) when compared with the baseline control (0.30 +/- 0.04 nmol/microg protein/min), with 42% and 31% average net increase, respectively. Pearson's correlation analyses indicated that sputum NEP activity was significantly associated with personal exposure product (elemental carbon concentration [mg/m(3)] x time [min]; C x T). The data suggest that changes in NEP activity may be an early, accurate endpoint for airway epithelial injury and provide a new insight into the mechanism of airway effects following particulate exposure.

Peptidase activities in serum and bronchoalveolar lavage fluid from allergic asthmatics--comparison with healthy non-smokers and smokers and effects of inhaled glucocorticoids

BACKGROUND

Neuropeptides may be involved in the pathogenesis of asthma by evoking neurogenic inflammation. Since the effects of neuropeptides are limited by peptidases, reduced activity of peptidases may contribute to the inflammatory process.

OBJECTIVE

We hypothesized that soluble peptidase activities are decreased in asthmatics and that inhaled glucocorticoids exert part of their anti-inflammatory action by increasing soluble peptidase activities.

METHODS

Serum and bronchoalveolar lavage (BAL) fluid was obtained from non-smoking and smoking volunteers and from allergic asthmatics both before and after treatment for 12 weeks with placebo or inhaled fluticasone propionate. Activities of neutral endopeptidase (NEP), aminopeptidase N (APN) and dipeptidyl peptidase IV (DPP IV) were determined using colourometric assays.

RESULTS

Reduced DPP IV activity in serum and reduced NEP activity in BAL fluid were found in healthy smokers compared with non-smokers. In contrast, no differences in peptidase activities in serum or BAL fluid were observed between allergic asthmatics and healthy non-smokers. Fluticasone propionate treatment did not affect peptidase activities in the asthmatic patients.

CONCLUSIONS

We conclude that reduced peptidase activities in serum or BAL fluid can be found in healthy smokers, but not in allergic asthmatics, and that inhaled glucocorticoids do not affect peptidase activities in BAL fluid or serum of asthmatics. Our results do not support the hypothesized dysfunction of peptidases in the asthmatic airways.

Biochemical changes in sarcoidosis

Biochemical markers in sarcoidosis are closely related to the immunological events and the activity of inflammatory effector cells at sites of granuloma formation. The markers can be measured in serum, then reflecting whole body concentration, or in BAL fluid, then indicating activity in the lung. Only calcium and ACE serum levels have gained a proven value in the clinical field.