Background: Chronic lung allograft dysfunction is a heterogeneous entity limiting long-term survival after lung transplantation. Different clinical phenotypes (bronchiolitis obliterans syndrome [BOS]-neutrophilic BOS-restrictive allograft syndrome [RAS]) have been identified but the mechanisms remain elusive.
Methods: In this study, we measured 34 different cytokines, chemokines, and growth factors in bronchoalveolar lavage fluid of 20 stable patients, 20 patients suffering from non-neutrophilic BOS, 17 from neutrophilic BOS, and 20 from RAS using classic enzyme-linked immunosorbent assay and multiplex technology.
Results: Total cell count and % neutrophils were elevated in neutrophilic BOS and RAS compared to stable and non-neutrophilic BOS patients, whereas also the % eosinophils was elevated at diagnosis of RAS. Levels of interleukin (IL)-1β (P<0.01), IL-1Rα (P<0.001), IL-6 (P<0.001), IL-8/CXCL8 (P<0.001), IP-10/CXCL10 (P<0.05), MCP-1/CCL2 (P<0.05), macrophage inflammatory protein (MIP)-1α/CCL3 (P<0.001), MIP-1β/CCL4, and vascular endothelial growth factor (VEGF; P<0.05) were differentially regulated in RAS compared to stable, whereas in neutrophilic BOS IL-1β (P<0.001), IL-1Rα (P<0.01), IL-7 (P<0.05), IL-8/CXCL8 (P<0.001), MCP-3/CXCCL7 (P<0.05) and MIP-1α/CCL-3 (P<0.05) were significantly upregulated compared to stable patients. We could not detect any differences between non-neutrophilic BOS and stable patients. Interestingly, bronchoalveolar lavage IL-6, interferon gamma-induced protein (IP)-10/CXCL10 and interferon-inducible T-cell alpha chemoattractant/chemokine (C-X-C motif) ligand 11 (ITAC/CXCL10) were associated with survival after diagnosis in RAS patients.
Conclusion: There were major differences in cytokine and chemokine expression in our different study groups. Especially IL-6, but also IP-10/CXCL10, and VEGF may be interesting mediators in RAS.
The underlying mechanisms of the different clinical phenotypes of chronic lung allograft dysfunction are studied. Analysis of broncho-alveolar lavage materials shows clear differences between non-neutrophilic BOS from neutrophilic BOS.
1 Department of Clinical and Experimental Medicine, Laboratory of Pneumology, Lung Transplant Unit, Katholieke Universiteit Leuven and University Hospital Gasthuisberg, Leuven, Belgium.
2 Department of Microbiology and Immunology, Rega Institute, KU Leuven, Leuven, Belgium.
Received 20 February 2014. Revision requested 13 March 2014.
Accepted 25 April 2014.
The authors declare no conflicts of interest.
S.E.V. is supported by the Onderzoeksfonds KU Leuven. G.M.V. is holder of GSK chair in respiratory pharmacology at the KU Leuven, and supported by Research Foundation Flanders (FWO): G.0723.10, G.0705.12 and G.0679.12 and Onderzoeksfonds KU Leuven (OT/10/050). R.V. is supported by the Research Foundation Flanders (FWO) (KAN2014 220.127.116.11) and Klinisch Onderzoeksfonds (KOF) KU Leuven. P.P. is supported by grants from the Belgian government (Belspo IAP 7-40), FWO (G0D6613N) and KU Leuven (GOA/13/014). D.S. is supported by funding of the KU Leuven (GOA/10/014 and PF/10/018) and FWO (G.0485.08 and G.0528.12). None of the funding sources have a role in study design, conduction and reporting of this study.
S.E.V. participated in data acquisition, writing of the article, and data analysis. D.R. and P.P. participated in data acquisition and writing of the article. R.V. participated in research design and writing of the article. E.V. participated in data acquisition, writing of the article, and data analysis. E.M. A.M., and D.S. participated in data acquisition. D.E.V.R. participated in the performance of the research. G.M.V. and B.M.V. participated in research design and writing ofthe article.
Correspondence: Stijn E. Verleden, Ph.D., KU Leuven, Lung Transplantation Unit, O&N1, 49 Herestraat, B-3000 Leuven, Belgium. (firstname.lastname@example.org).
Accepted July 22, 2014