Prognostic marker for Bronchiolitis Obliterans Syndrome after Lung Transplant: Collagen Type IV Alpha 5 Chain.

<bold>Introduction:</bold> Bronchiolitis obliterans syndrome (BOS) is the most common form of Chronic Lung Allograft Disfunction. Histologically, BOS lesions are characterized by extracellular matrix (ECM) remodeling. Collagen Type IV Alpha 5 Chain (COL4A5) forms ECM. This study analysed COL4A5 levels in the serum of BOS patients. <bold>Methods:</bold> 41 Lung Transplant patients were enrolled: 27 were affected by BOS and 14 (control group) were considered stable at the time of serum sampling. At the time of BOS diagnosis and before the clinical diagnosis (pre-BOS) serum samples were collected. COL4A5 levels were detected through the ELISA kit. <bold>Results:</bold> COL4A5 levels were higher in pre-BOS than in stable and BOS patients (p= 0.048 and p=0.039, respectively). Inverse correlation between COL4A5 levels and FEV1% was in BOS patients. COL4A5 was not influenced by comorbidities or therapies. Higher COL4A5 levels were associated with a worse prognosis. <bold>Conclusion:</bold> Serum concentrations of COL4A5 can be considered a good prognostic marker due to their association with survival and correlation with functional parameters.