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.