Skip to main content
NCBI home page
Clinical and Experimental Immunology logoLink to Clinical and Experimental Immunology
. 2010 Aug;161(2):342–347. doi: 10.1111/j.1365-2249.2010.04181.x

MRP14 is elevated in the bronchoalveolar lavage fluid of fibrosing interstitial lung diseases

N M Korthagen *, M M Nagtegaal *, C H M van Moorsel *, K M Kazemier †, J M M van den Bosch *,†, J C Grutters *,†
PMCID: PMC2909417  PMID: 20550547

Abstract

Pulmonary fibrosis is defined by an overgrowth of fibroblasts and extracellular matrix deposition, and results in respiratory dysfunction that is often fatal. It is the end stage in many chronic inflammatory interstitial lung diseases (ILD) such as sarcoidosis and idiopathic pulmonary fibrosis (IPF). The myeloid-related proteins (MRPs) belong to the S100 family of calcium-binding proteins and are highly expressed by neutrophils, macrophages and epithelial cells during chronic inflammation. MRP14 stimulates fibroblast proliferation in vitro and is expressed in granulomas from sarcoidosis patients. We hypothesized that MRP14 may be a biomarker for fibrotic interstitial lung diseases. The objective of this study was to investigate whether levels of MRP14 in the bronchoalveolar lavage fluid (BALF) of patients with sarcoidosis and IPF correlate with clinical parameters. We used an enzyme-linked immunosorbent assay (ELISA) to measure MRP14 in BALF of 74 sarcoidosis patients, 54 IPF patients and 19 controls. Mean BALF levels of MRP14 were elevated significantly in IPF (P < 0·001) and sarcoidosis (P < 0·05) patients compared to controls. MRP14 levels were associated linearly with sarcoidosis disease severity based on chest radiographic stage. Moreover, BALF MRP14 levels were correlated inversely with diffusion capacity and forced vital capacity in sarcoidosis patients. In IPF patients, a correlation with BALF neutrophil percentage was found. In conclusion, BALF MRP14 levels are elevated in IPF and sarcoidosis and are associated with disease severity in sarcoidosis. The results support the need for further studies into the role of MRP14 in the pathogenesis of lung fibrosis.

Keywords: calgranulin B, interstitial lung disease, IPF, sarcoidosis, S100A9

Introduction

Sarcoidosis and idiopathic pulmonary fibrosis (IPF) represent some of the most frequently occurring interstitial lung diseases (ILD). The aetiology of sarcoidosis and IPF remains unclear and lung biopsy is often required for diagnosis. Sarcoidosis is a multi-systemic granulomatous disease that primarily affects the lung and lymphatic system of the body. It occurs most often in young and middle-aged adults, and has an estimated mortality between 0·5 and 5% [1]. The cause of sarcoidosis is hypothesized to be an exaggerated cellular immune response to an unidentified antigen [2]. Pulmonary fibrosis occurs in 10–15% of sarcoidosis patients and is thought to be the result of chronic inflammation leading to the formation of scar tissue [3]. IPF is a rapidly progressing lung disease with a median survival of approximately 3 years [4]. The concept that IPF is inflammation-driven has been replaced by the theory that epithelial damage causes aberrant wound healing, resulting in the accumulation of fibrosis in the lung [5]. There is currently no effective treatment available, and lung transplantation remains the only option. IPF as well as pulmonary fibrosis in sarcoidosis are often characterized by an increased presence of neutrophils in the bronchoalveolar lavage fluid (BALF) [6,7]. Many studies focus on the protein content of BALF, hoping to find disease biomarkers that aid in diagnosis and provide insight into disease aetiology.

The myeloid-related protein (MRP)-14 (also known as calgranulin B and S100A9) belongs to the S100 family of calcium-binding proteins. These proteins are highly expressed by neutrophils, but also by macrophages and on epithelial cells in active inflammatory disease. The S100 proteins are thought to play a role in inflammatory conditions and tumorigenesis [8]. MRP14 was thought initially to occur only as a heterodimer complex with MRP8, but recently MRP14 is more often found to act on its own [9–12]. It is expressed in healthy skin and lung, while MRP8 is undetectable in these tissues [12]. Although the exact function of MRP14 is not known, it may be associated with disease severity in chronic inflammatory diseases and it was found to stimulate fibroblast proliferation in vitro[11,13,14]. MRP14 is expressed in affected tissue of gingivitis, rheumatoid arthritis, tuberculosis and sarcoidosis patients [12,14,15]. In sarcoidosis, MRP14 is expressed in epitheloid cells and giant cells composing the granuloma, whereas MRP8 is expressed only weakly or is even absent [15]. Using 2D electrophoresis, Bargagli et al. recently found MRP14 to be expressed differentially in the BALF of sarcoidosis and IPF patients [16], but it was not possible to assess quantitatively the relationship of MRP14 with patient characteristics.

In this study, we quantified BALF MRP14 levels in sarcoidosis and IPF patients using enzyme-linked immunosorbent assay (ELISA), and investigated whether MRP14 levels are associated with clinical parameters and disease severity. This is the first step towards understanding the role of MRP14 in fibrosing interstitial lung diseases.

Materials and methods

Patients and controls

In this study, 74 sarcoidosis patients (54 male, 20 female) and 54 IPF patients (44 male, 10 female) were included retrospectively (Table 1). IPF patients were diagnosed at the Department of Pulmonology of the St Antonius Hospital Nieuwegein in the Netherlands and included when current American Thoracic Society/European Respiratory Society (ATS/ERS) criteria were met [4]. All patients who underwent bronchoalveolar lavage (BAL) within 3 months from diagnosis were included. Eight IPF patients were treated with low-dose steroids at the time of diagnosis and BAL; the other IPF patients did not use immunosuppressants.

Table 1.

Characteristics of patients and controls.

Subjects (male/female) Steroid treated (yes/no) Age % pred. DLCO % pred. FVC % pred. FEV1 % BALF Neutrophils
Controls 19 (9/10) 0/19 22 ± 2 NA 109 ± 11 106 ± 11 1·9 ± 1·8
IPF 54 (44/10) 8/46 66 ± 11 48 ± 16 80 ± 21 85 ± 22 10·1 ± 11·5
Sarcoidosis 74 (54/20) 12/62 43 ± 12 77 ± 14 90 ± 19 77 ± 25 4·2 ± 12·2
Stage I 12 (9/7) 0/12 38 ± 14 86 ± 11 104 ± 9 99 ± 12 1·3 ± 1·1
Stage II 11 (8/3) 0/11 41 ± 10 80 ± 15 96 ± 18 91 ± 22 1·3 ± 0·7
Stage III 19 (15/6) 3/16 42 ± 13 78 ± 14 102 ± 12 93 ± 18 2·0 ± 2·8
Stage IV 32 (25/7) 9/23 46 ± 10 64 ± 17 79 ± 18 60 ± 17 3·6 ± 5·7
Open in a new tab

Values are given as mean ± standard deviation; NA: data not available. BALF: bronchoalveolar lavage fluid; DLCO: diffusion capacity of the lungs for carbon monoxide; FEV1: forced expiratory volume in 1 s; FVC: forced vital capacity; IPF: idiopathic pulmonary fibrosis.

Sarcoidosis patients were diagnosed in accordance with the consensus of the ATS/ERS/World Association of Sarcoidosis and Other Granulomatous Disorders (WASOG) statement on sarcoidosis [17]. Sarcoidosis patients were classified based on chest radiographic stages according to Scadding [18]. Stage I showed bilateral lymphadenopathy (12 patients), stage II lymphadenopathy with parenchymal abnormalities (11 patients), stage III showed no lymphadenopathy but parenchymal abnormalities (19 patients) and stage IV showed fibrosis (32 patients, 16 non-steroid users and 16 steroid users). We first selected patients who had BALF and a clear classifying chest radiograph at presentation and were not treated with steroids at that time (12/11/12/eight per stages I, II, III and IV, respectively). We subsequently added patients with BAL and classifying chest radiograph during follow-up; both steroid-positive (three at stage III and nine at stage IV) and steroid-negative patients (four at stage III and 13 at stage IV).

The control group consisted of 19 healthy subjects (nine male, 10 female) who underwent bronchoalveolar lavage.

The medical ethical committee of the St Antonius Hospital in Nieuwegein approved this study and all subjects gave formal written informed consent.

BAL

All patients underwent a BAL procedure as part of the diagnostic process. The bronchoscopy with BAL was performed according to international accepted guidelines [19,20]. BAL was performed in the right middle lobe with a total volume of 200 ml saline (4 × 50 ml aliquots), which was returned in two separate fractions. The first fraction returned, after instilling 50 ml saline, was used for microbial culture. The following three aliquots were pooled in fraction II and used for cell analysis and ELISA.

Clinical parameters

Values for forced expiratory volume in 1 s (FEV1), forced vital capacity (FVC) and diffusion capacity of the lungs for carbon monoxide (Dlco) were collected from all subjects that underwent lung function tests around the time of BAL. The parameters were expressed as a percentage of predicted values. The tests were performed according to international guidelines [21].

Data on blood cell counts and C-reactive protein (CRP) levels at the time of BAL as well as information on mortality and history of tobacco use was collected retrospectively.

ELISA

MRP14 ELISA (BMA Biomedicals, Augst, Switzerland) was performed in accordance with the manufacturer's instructions. The manufacturer has developed this ELISA in such a way that it minimizes cross-reactivity with the MRP8/14 heterodimer. The detection limit of the assay was 0·31 ng/ml. Samples that did not reach this limit were set at 50% of the detection limit. Samples equal to or lower than the negative control were set at zero.

Statistics

SPSS 15 (SPSS Inc., Chicago, IL, USA) and Graphpad Prism version 3 (Graphpad Software Inc., San Diego, CA, USA) were used for statistical analysis. Analysis of variance (anova) or Student's t-test was used to test differences in BALF MRP14 levels between patient groups. Correlations with patients' characteristics were determined using Spearman's rho test. Linear regression was used to test for an association with pulmonary radiographic stage in sarcoidosis patients. A P-value < 0·05 was considered significant.

Results

MRP14 levels in patients and controls

Control and patient characteristics are shown in Table 1. Mean BALF MRP14 levels were elevated significantly in IPF patients (P < 0·001) and sarcoidosis patients (P < 0·05) compared to controls (Fig. 1). In addition, mean BALF MRP14 levels were higher in IPF patients than in sarcoidosis patients (P < 0·01). When the sarcoidosis patients were subdivided according to chest radiographic stage, we found that the mean BALF MRP14 level was elevated significantly in stage IV sarcoidosis compared to controls (P < 0·005). When only sarcoidosis patients at presentation were included, the difference was also significant (P < 0·01). Interestingly, there appeared to be a linear association between BALF MRP14 levels and chest radiographic stages I, II, III and IV (R = 0·33, P < 0·005). When using a t-test to compare stage I and stage IV sarcoidosis, the difference was also significant (P < 0·05). There was no difference in mean BAL MRP14 level between patients who were treated with oral steroids and those who were not.

Fig. 1.

Fig. 1

Open in a new tab

Myeloid-related protein (MRP)-14 levels in the bronchoalvolar lavage (BAL) fluid of controls and patients. Mean and standard error of the mean are shown. (a) Levels in patients with idiopathic pulmonary fibrosis (IPF) and sarcoidosis compared to controls. (b) Levels in patients with sarcoidosis per pulmonary stage. In comparison with controls, mean bronchoalveolar lavage fluid (BALF) MRP14 levels were significantly higher in patients with sarcoidosis stage IV (P < 0·01). BALF MRP14 levels were associated linearly with sarcoidosis pulmonary radiographic stage (R = 0·33, P < 0·005). *P < 0·05; **P < 0·01; ***P < 0·001.

Correlation with clinical parameters

Higher BALF MRP14 levels were associated with a lower percentage of predicted DLCO (R = −0·49, P < 0·001), a lower percentage of predicted FVC (R = −0·44, P < 0·005) and a lower percentage of predicted FEV1 (R = −0·39, P < 0·01) in sarcoidosis patients (Fig. 2). However, lung function parameters were not correlated with BALF MRP14 levels in IPF patients. Interestingly, there was an association between BALF MRP14 levels and the percentage of neutrophils in BALF of IPF patients (R = 0·33, P < 0·05, Fig. 3), but this association was not found in sarcoidosis patients. BALF neutrophil percentage did show a weak correlation with sarcoidosis chest radiographic stage (R = 0·21, P < 0·05). We found no correlation between BALF MRP14 and macrophages or any other BALF cell types. Analysis of follow-up data from IPF patients did not reveal an association between BALF MRP14 levels and survival time. Smoking habits or gender did not affect BALF MRP14 levels in any patient group or controls. In addition, no correlation was found between BALF MRP14 and CRP levels in blood.

Fig. 2.

Fig. 2

Open in a new tab

Correlation between lung function parameters and bronchoalvolar lavage (BAL) myeloid-related protein (MRP)-14 levels in sarcoidosis patients. (a) Percentage of predicted forced vital capacity (FVC), R = –0·44, P < 0·005. (b) Percentage of predicted DLCO, R = 0·49, P < 0·001.

Fig. 3.

Fig. 3

Open in a new tab

Correlation between bronchoalveolar lavage fluid (BALF) myeloid-related protein (MRP)-14 levels and neutrophil percentage in idiopathic pulmonary fibrosis (IPF) patients. R = 0·33, P < 0·05.

Discussion

The aim of the present study was to quantify BALF MRP14 levels in sarcoidosis and IPF, and investigate whether they are associated with clinical parameters and disease severity. We found that the mean level of BALF MRP14 was elevated significantly in both diseases compared to controls, with mean levels significantly higher in IPF patients than in sarcoidosis patients. In sarcoidosis, the highest BALF MRP14 levels were found in the fibrotic stage IV sarcoidosis patients with a linear association of increasing levels across the radiographic stages. High BALF MRP14 levels were also associated with poor diffusion capacity and restrictive lung function measures. Therefore, our results demonstrate that BALF MRP14 levels are associated with pulmonary disease severity in sarcoidosis. We found no association between MRP14 levels and lung function in IPF. However, the observation that BALF MRP14 levels in IPF are higher than in sarcoidosis suggests that they reflect the difference in severity between these diseases.

This is the first study to report BALF MRP14 levels measured by ELISA. Previously, Bargagli et al. showed that BALF MRP14 levels in IPF were higher than in controls, using 2D-gelelectrophoresis [16]. They found no association with sarcoidosis stage or lung function parameters, but this is due most probably to the relatively small number of patients included.

Our larger group of patients enabled us to investigate the relationship between clinical parameters and MRP14. To verify that the elevated levels of MRP14 measured in BALF is not a reflection of systemic inflammation, we established that there was no association with CRP levels. The neutrophilia in BALF, which is often found in IPF and pulmonary stage IV in sarcoidosis, could be responsible for the elevated MRP14 levels seen in patients. However, BALF MRP14 levels were associated much more strongly with pulmonary stage in sarcoidosis than the neutrophil percentage. This suggests that MRP14 is a more specific biomarker for pulmonary disease severity in sarcoidosis than the amount of neutrophils in BALF. In addition, we observed a correlation between MRP14 and BALF neutrophils in IPF patients, but it was small, and no such correlation was found in sarcoidosis patients. The lack of correlation with neutrophils in sarcoidosis indicates that high BALF MRP14 levels do not simply reflect the presence of neutrophils in the lung, although all the MRP proteins together make up approximately 50% of the neutrophils cytosolic protein content [22]. Previous reports on a possible chemoattractant role for MRP14 are ambiguous. A study by Ryckman et al. [10] reported that MRP8, MRP14 and the heterocomplex MRP8/14 caused neutrophil chemotaxis in vitro and in vivo, and the same group also reported that antibodies against MRP14 blocked neutrophil recruitment [23]. However, other studies reported that MRP14 was not a chemoattractant for neutrophils and even repelled neutrophils [24,25]. Our data do not support a possible chemoattractant role for MRP14, but do not rule out the possibility that MRP14 is a chemoattractant for neutrophils under specific conditions; for instance, in some IPF patients. An mRNA expression study in rabbits showed that after neutrophils migrate from the blood to inflammatory sites the mRNA expression of MRP14 increases rapidly [26]. In addition, neutrophilic MRP14 is phosphorylated and translocated to the membrane during human neutrophil activation [27]. This suggests that MRP14 levels during inflammatory reactions are not dependent on the number of neutrophils present, but rather on their activity. Activated neutrophils can cause lung injury, epithelial cell apoptosis and basement membrane loss [28,29]. Neutrophils are also thought to mediate the transition from acute to chronic inflammation that may precede fibrosis [30]. Both neutrophils and macrophages have been reported to have an altered phenotype in the lungs of sarcoidosis patients [31,32]. It is possible that MRP14 is a marker for an activated subset of leucocytes. Further research is needed to reveal whether MRP14 expression is upregulated in neutrophils and alveolar macrophages in interstitial lung diseases.

It is intriguing to speculate about the exact role of MRP14. It may influence the functioning of leucocytes in several ways. For instance, a study by Newton and Hogg showed that MRP14 could be involved in the attachment of neutrophils to the endothelium, and could thus facilitate their migration [24]. MRP14 could also have a role in inhibiting the coagulation cascade during inflammatory disease [33]. Finally, MRP14 may directly influence the fibrotic process because its homodimer has been shown to induce proliferation of rat kidney fibroblasts in vitro[11]. All these processes could be involved in the pathogenesis of fibrotic pulmonary sarcoidosis and IPF.

Further research is needed to identify why MRP14 levels are elevated in the lungs of fibrosis patients and to investigate whether MRP14 plays a role in disease aetiology. It would also be interesting to investigate whether the other S100 proteins, such as MRP8, the MRP8/14 heterodimer and S100A12, play a similar role in ILD patients. These proteins are related closely, although they seem to have individual roles and can have different expression patterns [15,34,35]. They are thought to be proinflammatory mediators and have been associated with several neoplastic disorders [8]. MRP8/14 was elevated slightly in the plasma of pulmonary sarcoidosis compared to controls, but was lower than in patients with mild tuberculosis (TB) [36,37]. The MRP8/14 complex is involved in endothelial integrity loss and stimulates interleukin (IL)-8 production by airway epithelial cells [38,39]. Therefore, it could also be a part of the remodelling process in IPF [39]. S100A12 has been found to be elevated in the BALF of acute respiratory distress syndrome (ARDS) patients [40].

In conclusion, the S100 proteins are promising biomarkers in inflammation and cancer and, possibly, in lung diseases. The present study further explored the role of MRP14 in two predominant interstitial lung diseases. Our results confirm previous findings that BALF MRP14 levels are elevated in IPF. Furthermore, we show that BALF MRP14 levels are elevated in sarcoidosis, with highest levels in the fibrotic phenotype, and that they are associated with pulmonary disease severity. These results support the need for further study into the role of MRP14 in the aetiology of fibrosing interstitial lung diseases, and the application of this protein as a biomarker.

Disclosure

None.

References

  • 1.Reich JM. Mortality of intrathoracic sarcoidosis in referral vs population-based settings: influence of stage, ethnicity, and corticosteroid therapy. Chest. 2002;121:32–9. doi: 10.1378/chest.121.1.32. [DOI] [PubMed] [Google Scholar]
  • 2.Iannuzzi MC, Rybicki BA, Teirstein AS. Sarcoidosis. N Engl J Med. 2007;357:2153–65. doi: 10.1056/NEJMra071714. [DOI] [PubMed] [Google Scholar]
  • 3.Crystal RG, Bitterman PB, Rennard SI, Hance AJ, Keogh BA. Interstitial lung diseases of unknown cause. Disorders characterized by chronic inflammation of the lower respiratory tract. N Engl J Med. 1984;310:235–44. doi: 10.1056/NEJM198401263100406. [DOI] [PubMed] [Google Scholar]
  • 4.American Thoracic Society; European Respiratory Society. American Thoracic Society/European Respiratory Society International Multidisciplinary Consensus Classification of the Idiopathic Interstitial Pneumonias. This joint statement of the American Thoracic Society (ATS), and the European Respiratory Society (ERS) was adopted by the ATS board of directors, June 2001 and by the ERS Executive Committee, June 2001. Respir Crit Care Med. 2002;165:277–304. doi: 10.1164/ajrccm.165.2.ats01. [DOI] [PubMed] [Google Scholar]
  • 5.Noble PW, Homer RJ. Back to the future: historical perspective on the pathogenesis of idiopathic pulmonary fibrosis. Am J Respir Cell Mol Biol. 2005;33:113–20. doi: 10.1165/rcmb.F301. [DOI] [PubMed] [Google Scholar]
  • 6.Costabel U, Guzman J. Bronchoalveolar lavage in interstitial lung disease. Curr Opin Pulm Med. 2001;7:255–61. doi: 10.1097/00063198-200109000-00002. [DOI] [PubMed] [Google Scholar]
  • 7.Tutor-Ureta P, Citores MJ, Castejon R, et al. Prognostic value of neutrophils and NK cells in bronchoalveolar lavage of sarcoidosis. Cytometry B Clin Cytom. 2006;70:416–22. doi: 10.1002/cyto.b.20120. [DOI] [PubMed] [Google Scholar]
  • 8.Gebhardt C, Nemeth J, Angel P, Hess J. S100A8 and S100A9 in inflammation and cancer. Biochem Pharmacol. 2006;72:1622–31. doi: 10.1016/j.bcp.2006.05.017. [DOI] [PubMed] [Google Scholar]
  • 9.Anceriz N, Vandal K, Tessier PA. S100A9 mediates neutrophil adhesion to fibronectin through activation of beta2 integrins. Biochem Biophys Res Commun. 2007;354:84–9. doi: 10.1016/j.bbrc.2006.12.203. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 10.Ryckman C, Vandal K, Rouleau P, Talbot M, Tessier PA. Proinflammatory activities of S100: proteins S100A8, S100A9, and S100A8/A9 induce neutrophil chemotaxis and adhesion. J Immunol. 2003;170:3233–42. doi: 10.4049/jimmunol.170.6.3233. [DOI] [PubMed] [Google Scholar]
  • 11.Shibata F, Miyama K, Shinoda F, Mizumoto J, Takano K, Nakagawa H. Fibroblast growth-stimulating activity of S100A9 (MRP-14) Eur J Biochem. 2004;271:2137–43. doi: 10.1111/j.1432-1033.2004.04129.x. [DOI] [PubMed] [Google Scholar]
  • 12.Zwadlo G, Bruggen J, Gerhards G, Schlegel R, Sorg C. Two calcium-binding proteins associated with specific stages of myeloid cell differentiation are expressed by subsets of macrophages in inflammatory tissues. Clin Exp Immunol. 1988;72:510–15. [PMC free article] [PubMed] [Google Scholar]
  • 13.Seeliger S, Vogl T, Engels IH, et al. Expression of calcium-binding proteins MRP8 and MRP14 in inflammatory muscle diseases. Am J Pathol. 2003;163:947–56. doi: 10.1016/S0002-9440(10)63454-2. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 14.Frosch M, Vogl T, Seeliger S, et al. Expression of myeloid-related proteins 8 and 14 in systemic-onset juvenile rheumatoid arthritis. Arthritis Rheum. 2003;48:2622–6. doi: 10.1002/art.11177. [DOI] [PubMed] [Google Scholar]
  • 15.Delabie J, de Wolf-Peeters C, van den Oord JJ, Desmet VJ. Differential expression of the calcium-binding proteins MRP8 and MRP14 in granulomatous conditions: an immunohistochemical study. Clin Exp Immunol. 1990;81:123–6. doi: 10.1111/j.1365-2249.1990.tb05301.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 16.Bargagli E, Olivieri C, Prasse A, et al. Calgranulin B (S100A9) levels in bronchoalveolar lavage fluid of patients with interstitial lung diseases. Inflammation. 2008;31:351–4. doi: 10.1007/s10753-008-9085-z. [DOI] [PubMed] [Google Scholar]
  • 17.Statement on sarcoidosis. Joint Statement of the American Thoracic Society (ATS), the European Respiratory Society (ERS) and the World Association of Sarcoidosis and Other Granulomatous Disorders (WASOG) adopted by the ATS Board of Directors and by the ERS Executive Committee, February 1999. Am J Respir Crit Care Med. 1999;160:736–55. doi: 10.1164/ajrccm.160.2.ats4-99. [DOI] [PubMed] [Google Scholar]
  • 18.Scadding JG. Prognosis of intrathoracic sarcoidosis in England. A review of 136 cases after five years' observation. BMJ. 1961;2:1165–72. doi: 10.1136/bmj.2.5261.1165. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 19.Haslam PL, Baughman RP. Report of ERS Task Force: guidelines for measurement of acellular components and standardization of BAL. Eur Respir J. 1999;14:245–8. doi: 10.1034/j.1399-3003.1999.14b01.x. [DOI] [PubMed] [Google Scholar]
  • 20.Technical recommendations and guidelines for bronchoalveolar lavage (BAL). Report of the European Society of Pneumology Task Group. Eur Respir J. 1989;2:561–85. [PubMed] [Google Scholar]
  • 21.Standardization of Spirometry, 1994 Update. American Thoracic Society. Am J Respir Crit Care Med. 1995;152:1107–36. doi: 10.1164/ajrccm.152.3.7663792. [DOI] [PubMed] [Google Scholar]
  • 22.Hessian PA, Edgeworth J, Hogg N. MRP-8 and MRP-14, two abundant Ca(2+)-binding proteins of neutrophils and monocytes. J Leukoc Biol. 1993;53:197–204. [PubMed] [Google Scholar]
  • 23.Vandal K, Rouleau P, Boivin A, Ryckman C, Talbot M, Tessier PA. Blockade of S100A8 and S100A9 suppresses neutrophil migration in response to lipopolysaccharide. J Immunol. 2003;171:2602–9. doi: 10.4049/jimmunol.171.5.2602. [DOI] [PubMed] [Google Scholar]
  • 24.Newton RA, Hogg N. The human S100 protein MRP-14 is a novel activator of the beta 2 integrin Mac-1 on neutrophils. J Immunol. 1998;160:1427–35. [PubMed] [Google Scholar]
  • 25.Sroussi HY, Berline J, Palefsky JM. Oxidation of methionine 63 and 83 regulates the effect of S100A9 on the migration of neutrophils in vitro. J Leukoc Biol. 2007;81:818–24. doi: 10.1189/jlb.0706433. [DOI] [PubMed] [Google Scholar]
  • 26.Mori S, Goto K, Goto F, Murakami K, Ohkawara S, Yoshinaga M. Dynamic changes in mRNA expression of neutrophils during the course of acute inflammation in rabbits. Int Immunol. 1994;6:149–56. doi: 10.1093/intimm/6.1.149. [DOI] [PubMed] [Google Scholar]
  • 27.Guignard F, Mauel J, Markert M. Phosphorylation of myeloid-related proteins MRP-14 and MRP-8 during human neutrophil activation. Eur J Biochem. 1996;241:265–71. doi: 10.1111/j.1432-1033.1996.0265t.x. [DOI] [PubMed] [Google Scholar]
  • 28.Drakopanagiotakis F, Xifteri A, Polychronopoulos V, Bouros D. Apoptosis in lung injury and fibrosis. Eur Respir J. 2008;32:1631–8. doi: 10.1183/09031936.00176807. [DOI] [PubMed] [Google Scholar]
  • 29.Zemans RL, Colgan SP, Downey GP. Transepithelial migration of neutrophils: mechanisms and implications for acute lung injury. Am J Respir Cell Mol Biol. 2009;40:519–35. doi: 10.1165/rcmb.2008-0348TR. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 30.Tani K, Murphy WJ, Chertov O, Oppenheim JJ, Wang JM. The neutrophil granule protein cathepsin G activates murine T lymphocytes and upregulates antigen-specific IG production in mice. Biochem Biophys Res Commun. 2001;282:971–6. doi: 10.1006/bbrc.2001.4676. [DOI] [PubMed] [Google Scholar]
  • 31.Fortunati E, Kazemier KM, Grutters JC, Koenderman L, van den Bosch JM. Human neutrophils switch to an activated phenotype after homing to the lung irrespective of inflammatory disease. Clin Exp Immunol. 2009;155:559–66. doi: 10.1111/j.1365-2249.2008.03791.x. [DOI] [PMC free article] [PubMed] [Google Scholar]
  • 32.Kim DS, Paik SH, Lim CM, et al. Value of ICAM-1 expression and soluble ICAM-1 level as a marker of activity in sarcoidosis. Chest. 1999;115:1059–65. doi: 10.1378/chest.115.4.1059. [DOI] [PubMed] [Google Scholar]
  • 33.Hessian PA, Wilkinson L, Hogg N. The S100 family protein MRP-14 (S100A9) has homology with the contact domain of high molecular weight kininogen. FEBS Lett. 1995;371:271–5. doi: 10.1016/0014-5793(95)00905-o. [DOI] [PubMed] [Google Scholar]
  • 34.Henke MO, Renner A, Rubin BK, Gyves JI, Lorenz E, Koo JS. Up-regulation of S100A8 and S100A9 protein in bronchial epithelial cells by lipopolysaccharide. Exp Lung Res. 2006;32:331–47. doi: 10.1080/01902140600959580. [DOI] [PubMed] [Google Scholar]
  • 35.Robinson MJ, Hogg N. A comparison of human S100A12 with MRP-14 (S100A9) Biochem Biophys Res Commun. 2000;275:865–70. doi: 10.1006/bbrc.2000.3407. [DOI] [PubMed] [Google Scholar]
  • 36.Pechkovsky DV, Zalutskaya OM, Ivanov GI, Misuno NI. Calprotectin (MRP8/14 protein complex) release during mycobacterial infection in vitro and in vivo. FEMS Immunol Med Microbiol. 2000;29:27–33. doi: 10.1111/j.1574-695X.2000.tb01501.x. [DOI] [PubMed] [Google Scholar]
  • 37.Terasaki F, Fujita M, Shimomura H, et al. Enhanced expression of myeloid-related protein complex (MRP8/14) in macrophages and multinucleated giant cells in granulomas of patients with active cardiac sarcoidosis. Circ J. 2007;71:1545–50. doi: 10.1253/circj.71.1545. [DOI] [PubMed] [Google Scholar]
  • 38.Ahmad A, Bayley DL, He S, Stockley RA. Myeloid related protein-8/14 stimulates interleukin-8 production in airway epithelial cells. Am J Respir Cell Mol Biol. 2003;29:523–30. doi: 10.1165/rcmb.2002-0286OC. [DOI] [PubMed] [Google Scholar]
  • 39.Viemann D, Barczyk K, Vogl T, et al. MRP8/MRP14 impairs endothelial integrity and induces a caspase-dependent and -independent cell death program. Blood. 2007;109:2453–60. doi: 10.1182/blood-2006-08-040444. [DOI] [PubMed] [Google Scholar]
  • 40.Lorenz E, Muhlebach MS, Tessier PA, et al. Different expression ratio of S100A8/A9 and S100A12 in acute and chronic lung diseases. Respir Med. 2008;102:567–73. doi: 10.1016/j.rmed.2007.11.011. [DOI] [PMC free article] [PubMed] [Google Scholar]

Articles from Clinical and Experimental Immunology are provided here courtesy of British Society for Immunology

RESOURCES