We found that, in contrast to our initial hypothesis, CCR5 Δ32 carriers had significantly higher lung CT scores as compared with wt/wt individuals. Stratification on CCL5 G-403A genotype which was not related to disease phenotypes alone, did not modify the associations of CCR5 with CT score. Interestingly, we found the CX3CR1 1249 allele was associated with lower 1999 pneumoconiosis prevalence, the effect being evident in miners with high dust exposure. Further, CX3CR1 1249 and CCR5 Δ32 carriers had lower CT score in 1990, slower progression in score between 1990 and 1994, and the proportion of miners with pneumoconiosis in 1999 in each group was consistent with these results. This study is the first to consider simultaneously CCR5 and CCL5, CCR2 and CCL2, and CX3CR1 polymorphisms in an inflammatory lung disease. A strength of the study was the functional relevance of each SNP under study. Observed genotype and allele frequencies were similar to those reported previously in other Caucasians populations [5–7, 16, 17, 37, 38], with a higher frequency of subjects homozygous for the CX3CR1 M280 allele observed in our study. Other strengths of the study design include the availability of a quantitative validated phenotype measured twice 4 years apart and objective measurements of coal dust exposure, the main cause of pneumoconiosis. A limitation of the study was the relatively small sample size, which precludes detailed analyses to address simultaneously all genetic factors. Although Bonferroni correction for the independent comparisons on the main outcome (CT score in 1990) did not remove the statistical significance of the association with CCR5 Δ32, and the internal coherence of the results with other outcomes support the findings, the limited sample size imposes caution in the interpretation of the results. Further, no family-based data were available, and replication in other studies is warranted. The association of CCR5 Δ32, alone and after stratification on CCL5 G–403A, with more fibrosis measured by CT score, agrees with the association previously found with sarcoidosis [5]. In contrast, Spagnolo et al. [39] recently found no association of CCR5 haplotypes (including the CCR5 Δ32 insertion/deletion) with susceptibility to sarcoidosis, and CCR5 Δ32 has been associated with protection against asthma [4]. Distinct biological pathways during disease pathogenesis, and particularly the fibrotic process may partly account for the difference. As a loss of CCR5 is associated with macrophage dysfunction, we hypothetized that CCR5 Δ32 carriers could have impaired their cleaning capacity, leading to an increase in lung fibrosis. Further, association of CCR5 Δ32 SNP with fibrosis remains after stratification on CCL5 –403 genotype. The lack of clear association between the CCL5 –403 SNP and pneumoconiosis phenotypes and prevalence in our study was not surprising. Only one subject was homozygous for CCR5 Δ32, and heterozygosity in CCR5 Δ32 results in only a 50% decrease of CCR5 molecule expression on the cell suface [40]. Therefore, we were unable to completely evaluate the association of the CCL5 –403 SNP with pneumoconiosis according to the CCR5 Δ32 polymorphism. We also found no association of CCR2 V64I and CCL2 A–2578G SNPs with pneumoconiosis phenotypes and prevalence, in contrast to results previously reported for sarcoidosis and asthma [8,17]. Recently, Valentonyte et al. [41] found no association between CCR2 gene polymorphisms, including the V64I SNP, and the risk of sarcoidosis in 1203 patients and their relatives. However, they found positive linkage results in the 3p21 chromosomal region, suggesting a susceptibility gene in this location. In mice, contrasting effects of Ccr5 and Ccr2 deficiency on pulmonary inflammatory response to influenza A virus have been reported [42], and targeted deletion of Ccr3 (Ccr3−/−) were found to have enhanced hyper-reactivity in an airway inflammation model [3]. Further, whereas the hypothesis that inactivation of CCR2 or CCR5 would ameliorate rheumatoid arthritis, it was shown in murine models that Ccr5 null mice phenotype was similar to wild type and that collagen-induced arthritis phenotype of Ccr2 null mice mimicked that of human disease [43]. Pneumoconiosis is another collagen-related disease, and all these results suggest that the complex network of the chemokine system needs to be evaluated in detail, as recently shown in the study of Ferreira et al. [44]. Within the CCR cluster, we previously identified two common SNPs in the open reading frame of the CX3CR1 gene (V249I and T280M) [45] that associated with reduced risk of cardiovascular diseases [35,46,47]. Similarly, the present study found that the CX3CR1 I249 allele was associated with reduced pneumoconiosis prevalence. Our study is the first to evaluate the role of polymorphisms in CX3CR1 in an inflammatory lung disease. Fractalkine, the ligand of CX3CR1, is constitutively expressed in pulmonary endothelial and epithelial cells [48]. We hypothesize that fractalkine may be the primary signal allowing capture of CX3CR1-expressing inflammatory cells, and that CX3CR1 I249 variant, associated with enhanced adhesiveness [20], may decrease the extravasation of monocytes, leading to attenuation of airway inflammation. Association of CX3CR1 SNPs with reduced pneumoconiosis prevalence was more evident in miners with high exposure, i.e. in those having the higher recruitment of inflammatory cells in their airways. We hypothesize that the CCR5 axis may promote the migration of monocytes through the lung, and that both pairs of chemokines and their receptors may act sequentially or simultaneously to allow robust migration and fine positioning of cells expressing both chemokine receptors. In summary, our findings suggest that chemokine receptors CCR5 and CX3CR1 may be involved in the development of pneumoconiosis, an inflammatory and fibrotic lung disorder. Further, association of the CX3CR1 I249 allele with CT score and pneumoconiosis prevalence was more evident in miners with high cumulative exposure or in CCR5 Δ32 carriers, suggesting that interactions of chemokine receptor polymorphism with coal dust exposure (gene X environment) and between polymorphisms (gene X gene) may control disease susceptibility and progression. Our results also suggest the importance of considering simultaneously genetic variations in several chemokine receptors and balance with their ligands, and of combining gene with environmental parameters to better understand the aetiology of inflammatory diseases. |
1. Proudfoot AEI. Chemokine receptors: multifaceted therapeutic targets. Nat Rev Immunol. 2002;2:106–115. 2. Power CA. Knock out models to dissect chemokine receptor function in vivo. J Immunol Methods. 2003;273:73–82. 3. Gerard G, Rollins BJ. Chemokines and disease. Nature Immunol. 2001;2:108–115. 4. McGinnis R, Child F, Clayton S, Davies S, Lenney W, Illig T, Wjst M, Spurr N, Debouck C, Hajeer AH, Ollier WER, Strange R, Fryer AA. Further support for the association of CCR5 allelic variants with asthma susceptibility. Eur J Immunogenet. 2002;29:525–528. 5. Petrek M, Drabek J, Kolek V, Zlamal J, Welsh I, Bunce M, Weigl E, du Bois RM. CC Chemokine receptor gene polymorphisms in Czech patients with pulmonary sarcoidosis. Am J Respir Crit Care Med. 2000;162:1000–1003. 6. Sandford AJ, Zhu S, Bai TR, Fitzgerald JM, Paré PD. The role of the C-C chemokine receptor-5 Δ32 polymorphism in asthma and in the production of regulated on activation, normal T cells expressed and secreted. J Allergy Clin Immunol. 2001;108:69–73. 7. Srivastava P, Helms PJ, Stewart D, Main M, Russell G. Association of CCR5 Δ32 with reduced risk of childhood but not adult asthma. Thorax. 2003;58:222–226. 8. Hizawa N, Yamaguchi E, Furuya K, Jinushi E, Ito A, Kawakami Y. The role of the C-C chemokine receptor 2 gene polymorphism V64I (CCR2-64I) in sarcoidosis in a Japanese population. Am J Respir Crit Care Med. 1999;159:2021–2023. 9. Nickel RG, Casolaro V, Wahn U, Beyer K, Barnes KC, Plunkett BS, Freidhoff LR, Sengler C, Plitt JR, Schleimer RP, Caraballo L, Naidu RP, Levett PN, Beaty TH, Huang SK. Atopic dermatitis is associated with a functional mutation in the promoter of the C-C Chemokine RANTES. J Immunol. 2000;164:1612–1616. 10. Fryer AA, Spiteri MA, Bianco A, Hepple M, Jones PW, Strange RC, Makki R, Tavernier G, Smilie FI, Custovic A, Woodcock AA, Oilier WER, Hajeer AH. The –403 G→A promoter polymorphism in the RANTES gene is associated with atopy and asthma. Genes Immun. 2000;1:509–514. 11. Takada T, Suzuki E, Ishida T, Moriyama H, Ooi H, Hasegawa T, Tsukuda H, Gejyo F. Polymorphism in RANTES chemokine promoter affects extent of sarcoidosis in a Japanese population. Tissue antigens. 2001;58:293–298. 12. Dizier MH, Besse-Schmittler C, Guilloud-Bataille M, Annesi-Maesano I, Boussaha M, Bousquet J, Charpin D, Degioanni A, Gormand F, Grimfeld A, Hochez J, Hyne G, Lockhart A, Luillier-Lacombe G, Matran R, Meunier F, Neukirch F, Pacheco Y, Parent V, Paty E, Pin I, Pison C, Scheinmann P, Thobie N, Vervloet D, Kauffmann F, Feingold J, Lathrop M, Demenais F. Genome screen for asthma and related phenotypes in the French EGEA study. Am J Respir Crit Care Med. 2000;162:1812–1818. 13. Al-Abdulhadi SA, Helms PJ, Main M, Smith O, Christie G. Preferential transmission and association of the –403 G→A promoter RANTES polymorphism with atopic asthma. Genes Immun. 2005;6:24–30. 14. Hizawa N, Yamaguchi E, Konno S, Tanino Y, Jinushi E, Nishimura M. A functional polymorphism in the RANTES gene promoter is associated with the development of late-onset asthma. Am J Respir Crit Care Med. 2002;166:686–690. 15. Yao TC, Kuo ML, See LC, Chen LC, Yan DC, Ou LS, Shaw CK, Huang JL. The RANTES promoter polymorphism: A genetic risk factor for near-fatal asthma in Chinese children. J Allergy Clin Immunol. 2003;111:1285–1292. 16. Rovin BH, Lu L, Saxena R. A novel polymorphism in the MCP-1 gene regulatory region that influence MCP-1 expression. Biochem Biophys Res Commun. 1999;259:344–348. 17. Szalai C, Kozma GT, Nagy A, Bojszko A, Krikovszky D, Szabo T, Falus A. Polymorphism in the gene regulatory region of MCP-1 is associated with asthma susceptibility and severity. J Allergy Clin Immunol. 2001;108:375–381. 18. Yao TC, Wu KC, Chung HT, Shaw CK, Kuo ML, Wu CJ, Huang JL. MCP-1 gene regulatory region polymorphism in Chinese children with mild, moderate and near-fatal asthma. Allergy. 2004;59:436–441. 19. Laprise C, Sladek R, ponton A, Bernier MC, Hudson TJ, Laviolette M. Functional classes of bronchial mucosa genes that are differentially expressed in asthma. BMC Genomics. 2004;5:21–30. 20. Daoudi M, Lavergne E, Garin A, Tarantino N, Debre P, Pincet F, Combadiere C, Deterre P. Enhanced adhesive capacities of the naturally occurring Ile249-Met280 variant of the chemokine receptor CX3CR1. J Biol Chem. 2004;279:19649–19657. 21. D’Ambrosio D, Mariani M, Panina-Bordignon P, Sinigaglia F. Chemokines and their receptors guiding T lymphocyte recruitment in lung inflammation. Am J Respir Crit Care Med. 2001;164:1266–1275. 22. Reynolds HY. Lung inflammation and fibrosis: an alveolar macrophage-centered perspective from the 1970s to 1980s. Am J Respir Crit Care Med. 2005;171:98–102. 23. Gharaee-Kermani M, McCullumsmith RE, Charo IF, Kunkel SL, Phan SH. CC-chemokine receptor 2 required for bleomycin-induced pulmonary fibrosis. Cytokine. 2003;24:266–276. 24. Zhou Y, Kurihara T, Ryseck RP, Yang Y, Ryan C, Loy J, Warr G, Bravo R. Impaired macrophage function and enhanced T cell-dependent immune response in mice lacking CCR5, the mouse homologue of the major HIV-1 coreceptor. J Immunol. 1998;160:4018–4025. 25. Tyner JW, Uchida O, Kajiwara N, Kim EY, Patel AC, O’sullivan MP, Walter MJ, Schwendener RA, Cook DN, Danoff TM, Holtzman MJ. CCL5-CCR5 interaction provides antiapoptotic signals for macrophage survival during viral infection. Nat Med. 2005;11:1180–1187. 26. Capelli A, Di Stefano A, Lusuardi M, Gnemmi I, Dormer CF. Increased macrophage inflammatory protein-1 alpha and macrophage inflammatory protein-1 beta levels in bronchoalveolar lavage fluid of patients affected by different stages of pulmonary sarcoidosis. Am J Respir Crit Care Med. 2002;165:236–241. 27. Hasegawa M, Sato S, Echigo T, Hamaguchi Y, Yasui M, Takehara K. Up regulated expression of fractalkine/CX3CL1 and CX3CR1 in patients with systemic sclerosis. Ann Rheum Dis. 2005;64:21–28. 28. Rémy-Jardin M, Rémy J, Farre I, Marquette CH. Computed tomographic evaluation of silicosis and coal workers’ pneumoconiosis. Radiol Clin North Am. 1992;30:1155–1176. 29. Savranlar A, Altin R, Mahmutyazicioglu K, Ozdemir H, Kart L, Ozer T, Gundogdu S. Comparison of chest radiography and high-resolution computed tomography findings in early and low-grade coal worker’s pneumoconiosis. Eur J Radiol. 2004;51:175–180. 30. Bourgkard E, Bernadac P, Chau N, Bertrand JP, Teculescu D, Pham QT. Can the evolution to pneumoconiosis be suspected in coal miners ? A longitudinal study. Am J Respir Crit Care Med. 1998;158:504–509. 31. ] Nadif R, Jedlicka A, Mintz M, Bertrand JP, Kleeberger S, Kauffmann F. Effect of TNF and LTA polymorphisms on biological markers of response to oxidative stimuli in coal miners: a model of gene-environment interaction. J Med Gen. 2003;40:96–103. 32. Attfield MD, Morring K. The derivation of estimated dust exposures for U.S. coal miners working before 1970. Am Ind Hyg Assoc J. 1992;53:248–255. 33. Nadif R, Bourgkard E, Dusch M, Bernadac P, Bertrand JP, Mur JM, Pham QT. Relations between occupational exposure to coal mine dusts, erythrocyte catalase and Cu++/Zn++ superoxide dismutase activities, and the severity of coal worker’s pneumoconiosis. Occup Environ Med. 1998;55:533–540. 34. International Labour Office (ILO). ILO division of Occupational Safety and Health Sciences. Geneva: 1980. Guideline for the use of ILO international classification of radiographs of pneumoconiosis. publication 22. 35. Lavergne E, Labreuche J, Daoudi M, Debre P, Cambien F, Deterre P, Amarenco P, Combadiere C. GENIC Investigators. Adverse associations between CX3CR1 polymorphisms and risk of cardiovascular or cerebrovascular disease. Arterioscler Thromb Vase Biol. 2005;25:847–853. 36. Tregouet DA, Barbaux S, Poirier O, Blankenberg S, Bickel C, Escolano S, Rupprecht HJ, Meyer J, Cambien F. Tiret L; AtheroGene group. SELPLG gene polymorphisms in relation to plasma SELPLG levels and coronary artery disease. Ann Hum Genet. 2003;67:504–511. 37. Bayley JP, Baggen JM, van der Pouw-Kraan T, Crusius JB, Huizinga TW, Verweij CL. Association between polymorphisms in the human chemokine receptor genes CCR2 and CX3CR1 and rheumatoid arthritis. Tissue Antigens. 2003;62:170–174. 38. Gugl A, Renner W, Seinost G, Brodmann M, Pabst E, Wascher TC, Paulweber B, Iglseder B, Pilger E. Two polymorphisms in the fractalkine receptor CX3CR1 are not associated with peripheral arterial disease. Atherosclerosis. 2003;166:339–43. 39. Spagnolo P, Renzoni EA, Wells AU, Copley SJ, Desai SR, Sato H, Grutters JC, Abdallah A, Taegtmeyer A, du Bois RM, Welsh KI. C-C chemokine receptor 5 gene variants in relation to lung disease in sarcoidosis. Am J Respir Crit Care Med. 2005;172:721–728. 40. Landau NR. Recent advances in AIDS research: genetics, molecular biology and immmunology. Curr Opin Immunol. 1999;11:449–450. 41. Valentonyte R, Hampe J, Croucher PJ, Muller-Quernheim J, Schwinger E, Schreiber S, Schurmann. Study of C-C chemokine receptor 2 alleles in sarcoidosis, with emphasis on family based analysis. Am J Respir Crit Care Med. 2005;171:1136–1141. 42. Dawson TC, Beck MA, Kuziel WA, Henderson F, Maeda N. Contrasting effects of CCR5 and CCR2 deficiency in the pulmonary inflammatory response to influenza A virus. Am J Pathol. 2000;156:1951–1959. 43. Quinones MP, Ahuja SK, Jimenez F, Schaefer J, Garavito E, Rao A, Chenaux G, Reddick RL, Kuziel WA, Ahuja SS. Experimental arthritis in CC chemokine receptor 2-null mice closely mimics severe human rheumatoid arthritis. J Clin Invest. 2004;113:856–866. 44. Ferreira AM, Rollins BJ, Faunce DE, Burns AL, Zhu X, Dipietro LA. The effect of MCP-1 depletion on chemokine and chemokine-related gene expression: evidence for a complex network in acute inflammation. Cytokine. 2005;30:64–71. 45. Faure S, Meyer L, Costagliola D, Vaneensberghe C, Genin E, Autran B, Delfraissy JF, McDermott DH, Murphy PM, Debre P, Theodorou I, Combadiere C. Rapid progression to AIDS in HIV+ individuals with a structural variant of the chemokine receptor CX3CR1. Science. 2000;287:2274–2277. 46. McDermott DH, Fong AM, Yang Q, Sechler JM, Cupples LA, Merrell MN, Wilson PW, D’Agostino RB, O’Donnell CJ, Patel DD, Murphy PM. Chemokine receptor mutant CX3CR1-M280 has impaired adhesive function and correlates with protection from cardiovascular disease in humans. J Clin Invest. 2003;111:1241–1250. 47. Moatti D, Faure S, Fumeron F, Amara Mel-W, Seknadji P, McDermott DH, Debre P, Aumont MC, Murphy PM, de Prost D, Combadiere C. Polymorphism in the fractalkine receptor CX3CR1 as a genetic risk factor for coronary artery disease. Blood. 2001;97:1925–1928. 48. Rimaniol AC, Till SJ, Garcia G, Capel F, Godot V, Balabanian K, Durand-Gasselin I, Varga EM, Simonneau G, Emilie D, Durham SR, Humbert M. The CX3C chemokine fractalkine in allergic asthma and rhinitis. J Allergy Clin Immunol. 2003;112:1139–1146. |