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BAL Fluid Surfactant Protein C Level Is Related to Parenchymal Lung Disease in Children With SarcoidosisSurfactant Protein C Levels in Sarcoidosis FREE TO VIEW

Loïc Guillot, PhD; Florence Flamein, MD; Guillaume Thouvenin, MD; Michèle Boulé, MD, PhD; Hubert Ducou le Pointe, MD, PhD; Laurence Jonard, PharmD, PhD; Annick Clement, MD, PhD; Ralph Epaud, MD
Author and Funding Information

From INSERM U938 (Drs Guillot, Flamein, Thouvenin, Boulé, and Clement); UPMC, University of Paris 6 (Drs Guillot, Flamein, Thouvenin, Boulé, Ducou le Pointe, Jonard, and Clement); AP-HP, Hôpital Trousseau (Drs Thouvenin, Boulé, Ducou le Pointe, Jonard, and Clement); the Pediatric Pulmonary Department (Drs Thouvenin and Clement), the Radiology Department (Dr Ducou le Pointe), and the Biochemistry Department (Dr Jonard), the Université Paris-Est Créteil Val de Marne (Dr Epaud); INSERM, Unité U955 (Dr Epaud); and Centre Hospitalier Intercommunal (Dr Epaud).

Correspondence to: Ralph Epaud, MD, Pediatric Department, Centre Hospitalier Intercommunal, 40 avenue de Verdun, 94000 Créteil, France; e-mail: ralph.epaud@chicreteil.fr


Funding/Support: This work was supported by Assistance Publique-Hôpitaux de Paris and INSERM.

Financial/nonfinancial disclosures: The authors have reported to CHEST that no potential conflicts of interest exist with any companies/organizations whose products or services may be discussed in this article.

Reproduction of this article is prohibited without written permission from the American College of Chest Physicians (http://www.chestpubs.org/site/misc/reprints.xhtml).


© 2011 American College of Chest Physicians


Chest. 2011;140(4):1104-1105. doi:10.1378/chest.11-0681
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Surfactant protein C (SP-C) is a hydrophobic protein exclusively synthesized by type 2 alveolar epithelial cells from a 197 amino acid propeptide form (proSP-C) after a complex multistep posttranscriptional processing.1 Sarcoidosis is a systemic disease of unknown cause characterized by noncaseating epithelioid granulomas2 that may disturb the synthesis of SP-C. We aimed to assess the relationship between alveolar SP-C expression and parenchymal lung disease in children with pulmonary sarcoidosis.

Eighteen children with histologic proven sarcoidosis (white, n = 8; black African, n = 5; French Antilles, n = 5) were evaluated for parenchymal lung disease by high-resolution CT scans and respiratory function tests, including measurements of FVC and dynamic lung compliance (Cl,dyn).3 Patients were divided, after radiographic staging,4 in two groups based on the absence of pulmonary infiltrations (API group; stages 0 and I, nine patients) or the presence of pulmonary infiltrations (PI group; stages II and III, nine patients). All patients underwent fiberoptic bronchoscopy with BAL before treatment onset for 17 of the 18 patients. BAL fluid (BALF) proSP-C and mature SP-C expression levels were assessed by Western blot using proSP-C and mature SP-C antibodies (Seven Hills Bioreagents; Cincinnati, Ohio) as previously described.5 Signals were scanned, analyzed by Quantity One software (Bio-Rad; Marnes-La-Coquette, France), and expressed as arbitrary units.

We have shown that BALF proSP-C levels were significantly higher in the PI group compared with the API group, whereas BALF mature SP-C levels were significantly lower in the PI group compared with API group (Table 1). The ProSP-C/mature SP-C ratio was also significantly higher in the PI group compared with the API group. Furthermore, elevated proSP-C (or decreased mature SP-C) levels were associated with lower Cl,dyn, and we observed a strong correlation between both proSP-C and SP-C BALF expression and Cl,dyn (r = −0.52, P = .03 for proSP-C and r =0.681, P = .007 for mature SP-C). No correlation was shown between proSP-C or mature SP-C levels and FVC (r = −0.18, P = .48 for proSP-C and r =0.375, P = .16 for mature SP-C).

Table Graphic Jump Location
Table 1 —Functional and BALF Features in Patients With or Without Parenchymal Lung Disease

Data are expressed as mean ± SEM. API = absence of pulmonary infiltration; AU = arbitrary unit; BALF = BAL fluid; Cl,dyn = dynamic compliance; PI = presence of pulmonary infiltration; proSP-C = surfactant protein propeptide form; SP-C = surfactant protein; VC = vital capacity.

a 

P values > .05 are not shown.

Our results highlight the relation among SP-C expression, parenchymal lung disease, and Cl,dyn in children with sarcoidosis. Although a change in SP-C expression levels is usually observed in SFTPC mutation-associated disorders,5 no mutation in the SFTPC gene was identified in our patients. Furthermore, proSP-C and mature SP-C levels in the API group are similar to those observed in our control subjects (without interstitial lung disease) from a previous study.5 Hence, changes observed in individuals with parenchymal lesions likely reflect damage or release of proSP-C from epithelial cells as a consequence of granulomatous inflammation. This study suggests that assessment of SP-C levels in BALF may represent a complementary tool for therapeutic orientation and follow-up of pediatric sarcoidosis.

Role of sponsors: The sponsor had no role in the design of the study, the collection and analysis of the data, or in the preparation of the manuscript.

Other contributions: We thank Harriet Corvol, MD, PhD; Katarina Chadelat, MD; and Céline Charlier, PhD, for their helpful comments on study design and manuscript. We also thank Marie Claude Miesch for technical assistance on Western blot.

Weaver TE, Conkright JJ. Function of surfactant proteins B and C. Annu Rev Physiol. 2001;63:555-578 [CrossRef] [PubMed]
 
Milman N, Hoffmann AL. Childhood sarcoidosis: long-term follow-up. Eur Respir J. 2008;313:592-598 [CrossRef] [PubMed]
 
Baculard A, Blanc N, Boulé M, et al. Pulmonary sarcoidosis in children: a follow-up study. Eur Respir J. 2001;174:628-635 [CrossRef] [PubMed]
 
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;1602:736-755 [PubMed]
 
Thouvenin G, Abou Taam R, Flamein F, et al. Characteristics of disorders associated with genetic mutations of surfactant protein C. Arch Dis Child. 2010;956:449-454 [CrossRef] [PubMed]
 

Figures

Tables

Table Graphic Jump Location
Table 1 —Functional and BALF Features in Patients With or Without Parenchymal Lung Disease

Data are expressed as mean ± SEM. API = absence of pulmonary infiltration; AU = arbitrary unit; BALF = BAL fluid; Cl,dyn = dynamic compliance; PI = presence of pulmonary infiltration; proSP-C = surfactant protein propeptide form; SP-C = surfactant protein; VC = vital capacity.

a 

P values > .05 are not shown.

References

Weaver TE, Conkright JJ. Function of surfactant proteins B and C. Annu Rev Physiol. 2001;63:555-578 [CrossRef] [PubMed]
 
Milman N, Hoffmann AL. Childhood sarcoidosis: long-term follow-up. Eur Respir J. 2008;313:592-598 [CrossRef] [PubMed]
 
Baculard A, Blanc N, Boulé M, et al. Pulmonary sarcoidosis in children: a follow-up study. Eur Respir J. 2001;174:628-635 [CrossRef] [PubMed]
 
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;1602:736-755 [PubMed]
 
Thouvenin G, Abou Taam R, Flamein F, et al. Characteristics of disorders associated with genetic mutations of surfactant protein C. Arch Dis Child. 2010;956:449-454 [CrossRef] [PubMed]
 
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