Table 2.
Results of the systematic review
| Author and year | Study design | Setting | Clinical stability | Sample size | Assay manufacturer (methods) | Quantitative findings | Biological matrix | Major results |
|---|---|---|---|---|---|---|---|---|
| Stockley, 1984 [18] | Cross-sectional | Monocentric, outpatients | Stable state Exacerbation |
34 Bx patients | Elastin-agarose diffusion plate (in-home assay) | NE activity (μg x mL): grade1 19.5; grade2 48.2; grade3 62.9 | Sputum | Correlation with sputum macroscopic appearance |
| Smallman, 1984 [6] | Cross-sectional/Prospective | Monocentric, outpatients | Stable state | 8 Bx patients | Elastin-agarose diffusion plate (in-home assay) | NE activity (μg x mL): not quantified but evaluated as present/not present (lower limit of detection 0.8) | Sputum | Inverse correlation with ciliary beat frequency NE reduction after short-term antibiotic therapy |
| Fujita, 1992 [60] | Cross-sectional | Monocentric, outpatients | Stable state | 9 Bx patients in a cohort of 64 chronic respiratory diseases +15 healthy subjects | Elisa for NE- A1AT complex (in-home assay) | NE-A1AT complex levels (μg x L): 558 ± 198; healthy subjects 122 ± 4 | Blood | NE- A1AT complex higher in Bx patients than in healthy subjects |
| Lloberes, 1992 [63] | Cross- sectional | Monocentric, outpatients | Stable state | 26 Bx patients | Elastin-agarose diffusion plate (in-home assay) | NE activity (μg × 100 μL): purulent 7.75 (0–21.5); mucopurulent 1.3 (0–19.5); mucoid 0 | Sputum | Correlation with sputum macroscopic appearance |
| Ip, 1993 [71] | Prospective | Monocentric, outpatients | Exacerbation | 12 Bx patients | Spectrophotometry, SLAPN substrate | NE activity (mU × 100 μL): baseline 50.5 ± 17.1; exacerbation before atb 51.8 ± 25.4; 1-week atb −24.3 ± 20.7; 2-week atb −35.1 ± 17.8; 2-week after atb −12.1 ± 35.6; 6-week after atb −32.8 ± 26.8 | Sputum | NE reduction after short-term antibiotic therapy |
| Llewellyn-Jones, 1995 [15] | Prospective | Monocentric, outpatients | Stable state | 9 Bx patients +8 healthy subjects | Fluorescence (in-home assay) | NE activity (μg x mL−1): day -7th 4.0 ± 0.46; baseline 4.15 ± 0.69; day 14th 4.25 ± 0.63; day 28th 4.39 ± 0.65; day 63th 4.03 ± 0.67 | Blood | No NE reduction after indomethacin |
| Sepper, 1995 [74] | Cross-sectional | Monocentric, outpatients | Stable state | 24 Bx patients +15 healthy subjects | Spectrophotometry, SAAVNA substrate | NE activity (mU x g): mild group 0.21 ± 0.09; moderate group 1.87 ± 1.12; severe group 2.64 ± 1.63; healthy subjects 0.09 ± 0.03 | BAL | Correlation with symptoms, exacerbation rate and radiological severity |
| Nakamura, 1997 [56] | Cross-sectional | Monocentric, outpatients | Stable state | 3 Bx patients in a cohort of 8 chronic respiratory diseases +15 healthy subjects | Elisa (in-home assay) | Quantitative findings only reported as figures | BAL | NE higher in Bx than in healthy subjects |
| Gaga, 1998 [57] | Cross-sectional | Monocentric, outpatients | Stable state | 12 Bx patients +11 healthy subjects | Immunocitochemistry (in-home assay) | Neutrophils (cells x mm3): Bx patients 114; healthy subjects 41 | Bronchial biopsies | NE higher in Bx than in healthy subjects |
| Nakamura, 1999 [78] | Prospective | Monocentric, outpatients | Stable state | 3 Bx patients in a cohort of 10 chronic respiratory diseases | Elisa (in-home assay) | NE levels (μg x mL−1): baseline 125.5 ± 47.5; 16.8 ± 7.1 after atb | BAL | Ne reduction after 3-month roxithromycin |
| Ichikawa, 1999 [64] | Cross-sectional | Monocentric, outpatients | Stable state | 18 Bx patients in a cohort of 59 chronic respiratory diseases +28 healthy subjects | Spectrofluorometry AMC substrate | NE activity (U): purulent 1239.2 ± 1017.8; mucoid 45.7 ± 115.1 | Sputum | Inverse correlation with IgBF levels and sputum purulence |
| Hill, 2000 [16] | Cross- sectional | Monocentric, outpatients | Stable state | 43 Bx patients in a cohort of 160 chronic respiratory diseases | Spectrophotometry | NE levels (nM): mixed flora 0 (0–20); high bacterial load 21 (4–40) | Sputum | Correlation with sputum bacterial load |
| Schaaf, 2000 [68] | Cross-sectional | Monocentric, outpatients | Stable state | 11 Bx patients in a cohort of 66 chronic respiratory diseases +12 healthy subjects | Immunoluminometry Colorimetry |
NE-A1AT complex levels (ng x mL): Bx patients 44 (15–152); healthy subjects 3 (0–15) | BAL | NE higher in Bx than in healthy subjects Correlation with P. aeruginosa chronic respiratory infection |
| Tsang, 2000 [75] | Cross-sectional | Monocentric, outpatients | Stable state | 30 Bx patients | Spectrophotometry, SAAVNA substrate | NE levels (U x mL): 6.60 ± 3.13 | Sputum | Correlation with 24 h sputum volume, sputum inflammatory markers (leukocytes, IL-B and TNFa), radiological severity and spirometry (FEV1, FVC) |
| Zheng, 2000 [69] | Cross-sectional | Monocentric, outpatients | Stable state | 35 Bx patients +18 healthy subjects | Spectrophotometry, SAAVNA substrate | NE levels (Unit x mL−1): P. aeruginosa 222.6 (18.3–267.5); 8.7 (0.6–186.7) | Sputum | Correlation with P. aeruginosa chronic respiratory infection |
| Viglio, 2000 [21] | Cross-sectional | Monocentric, outpatients | Stable state | 13 Bx patients in a cohort of 54 chronic respiratory diseases +24 healthy subjects | HPCE | DES (μg x g creatinine−1): Bx patients 23.39 ± 2.05; CF 23.39 ± 2.02; A1AT deficiency 22.3 ± 7.74; exacerbated COPD 17.15 ± 3.42; stable COPD 14.17 ± 2.33; smokers 11.97 ± 2.75; healthy subjects 9.31 ± 2.75 | Urine | Desmosine higher in stable Bx than in other chronic respiratory disease and healthy subjects |
| Angrill, 2001 [62] | Cross-sectional | Monocentric, outpatients | Stable state | 49 Bx patients +9 healthy subjects | Immunoassay (?) | NE levels (μg x L): colonized patients 231 (15–2930); not colonized patients 45 (8–2280); healthy subjects 34 (9–44) | BAL | NE higher in Bx than in healthy subjects Correlation with neutrophils, IL8 and TNFa in BALF Correlation with bacterial chronic respiratory infection. |
| Stockley, 2001 [65] | Cross-sectional | Monocentric, outpatients | Stable state | 14 Bx patients +9 smokers | Spectrophotometry, MSAPN substrate Elisa (in-home assay) |
NE levels (μM): sputum colour value-3 0.006 ± 1.0; sputum colour value-7 4.14 ± 1.0 | Sputum | Correlation with sputum macroscopic appearance Correlation with MPO and 24 h sputum volume Inverse correlation with A1AT |
| Zheng, 2001 [59] | Cross-sectional | Monocentric, outpatients | Stable state | 14 Bx patients +15 healthy subjects | Anti-NE antibodies | Median neutrophils x mm−2: Bx patients 608 (101–1013); healthy subj. 127 (24–630) | Endobronchial biopsies | NE higher in bronchiectatic lamina propria than in healthy subjects |
| Vandivier, 2002 [58] | Prospective | Monocentric, outpatients | Exacerbation | 6 Bx patients in a cohort of 18 chronic respiratory diseases | Spectrophotometry | NE (U x mL): Bx patients 10; CF 3 | Sputum | NE higher in Bx NE as cause of delay in apoptotic cell clearance |
| Chan, 2003 [12] | Cross-sectional | Monocentric, outpatients | Stable state | 10 Bx patients | Spectrophotometry | NE activity range (mM): 0.9–1.2 | Sputum | NE not only as free but complexed with polyanionic partners (syndecan-1) and A1AT |
| Watt, 2004 [72] | Prospective | Monocentric, outpatients | Exacerbation | 15 Bx patients +10 healthy subjects | Kinetic assays (?) | NE levels (ng x mL): after atb −73,451 (135,495–12,303) | Sputum | NE reduction after short-term antibiotic therapy |
| Chan, 2009 [61] | Cross-sectional | Monocentric, outpatients | Stable state | 12 Bx patients | Spectrophotometry, MSAPN substrate ELISA (in-home assay) |
NE activity (mM): 1.3 (1–2) | Sputum | NE complexed with syndecan-1 Description of protease/anti-protease balance |
| Murray, 2010 [77] | RCT | Monocentric, outpatients | Stable state | 65 Bx patients | Elastin-agarose diffusion plate (in-home assay) | NE activity gentamicin group vs placebo: (U x mg): baseline 3.6 (0–17.6) vs 4.1 (0–19); 3-month 0 (0–0) vs 0 (0–20.4); 6-month 0 (0–2.9) vs 0 (0–29.1); 9-month 0 (0–7.6) vs 0.9 (0–19.4); 12- month 0 (0–1.8) vs 1.8 (0.17–16); 15-month 7.1 (0–56) vs 2.8 (0.9–18.2) | Sputum | NE reduction after 3-month inhaled gentamicin |
| Chalmers, 2012 [67] | Prospective | Monocentric, outpatients | Stable state Exacerbation |
385 Bx patients | Elastin-agarose diffusion plate (in-home assay) | NE activity (μg x mL): P. aeruginosa infected 4.9 (1.2–68); P. aeruginosa not infected 1.2 (0.4–147.2); other quantitative findings only reported as figures | Sputum | Correlation with bacterial load and radiological severity |
| Mandall, 2013 [73] | Prospective | Monocentric, outpatients | Stable state | 163 Bx patients | Spectrophotometry | NE activity (U x mL): GERD group 5; non-GERD group 3 | Sputum | Correlation with GERD |
| Stockley, 2013 [55] | RCT | Multicentric, outpatients | Stable state | 38 Bx patients | Custom-made immunoassay (in-home assay) for both NE and desmosine | NE activity AZD9668 group vs placebo (μM x L): baseline 24.54 vs 7.28; end of treatment 15.92 vs 7.49 | Sputum Urine |
NE reduction after 28-day of oral AZD9668 No difference in desmosine between AZD9668 and placebo |
| Goeminne, 2014 [66] | Cross-sectional | Monocentric, outpatients | Stable state | 49 Bx patients +12 healthy subjects | Enzymatic assay | NE activity (μg x mL): Bx patients 15 (3–23); healthy subject 0.8 (0.4–1.2) | Sputum | Correlation with TNFA, CXCL8 and MMP-9 Inverse correlation with FVC |
| Liu, 2014 [14] | RCT | Monocentric, outpatients | Stable state | 43 Bx patients | ELISA (in-home assay) | Quantitative findings only reported as figures | Sputum | NE reduction after 6-month roxythromicin |
| Aliberti, 2016 [70] | Prospective | Multicentric, outpatients | Stable state | 1145 Bx patients | different assays according to different centers | Quantitative findings only reported as figures | Sputum | Correlation with ‘P. aeruginosa‘cluster and ‘Other chronic infection’ cluster |
| Chalmers, 2016 [17] | Prospective | Stable state Exacerbation |
381 Bx patients | Immunoassay (ProAxsis LTD) Kinetic assay (Sigma Aldrich) LC-MS for desmosine |
NE levels (μg x mL): baseline 0.39 (0–23.5); onset of exacerbation 57.0 (3.3–145); after 14-day atb 0 (0–125.8); 1-month later 1.3 (0–29.9) | Sputum Serum |
Correlation with BSI, MRC, FEV1, bacterial load, radiological severity Correlation with higher exacerbation rate, FEV1 decline, all-cause mortality during 3-year follow up NE increase during exacerbations and NE reduction after short-term antibiotic therapy Serum desmosine is associated with age and disease severity |
Definitions: atb antibiotics, A1AT alpha-1 anti-trypsin, BAL broncho-alveolar lavage, Bx bronchiectasis, DES desmosine, NE neutrophil elastase, SLAPN succinyl-trialanine-nitroanilide, SAAVNA succinyl-Ala-Ala-Val-nitroanilide, MSAPN methoxysuccinyl-Ala-Ala-Pro-Val-paranitroanilide, HPCE high-performance capillary electrophoresis, LC-MS liquid chromatography-mass spectrometry