Probes for TSLP

Chronic lung allograft dysfunction (CLAD) is the leading cause of death among lung transplant recipients. Eosinophils, effector cells of type 2 immunity, are implicated in the pathobiology of many lung diseases and prior studies suggest their presence associates with acute rejection or CLAD after lung transplantation.Does histological allograft injury or respiratory microbiology correlate with the presence of eosinophils in bronchoalveolar lavage fluid (BALF)? Does early posttransplant BALF eosinophilia associate with future CLAD development, including after adjustment for other known risk factors?We analyzed BALF cell count, microbiology, and biopsy data from a multicenter cohort of 531 lung recipients with 2592 bronchoscopies over the first posttransplant year. Generalized estimating equation models were utilized to examine the correlation of allograft histology or BALF microbiology with the presence of BALF eosinophils. Multivariable Cox regression was used to determine the association between ≥1% BALF eosinophils in the first posttransplant year and definite CLAD. Expression of eosinophil-relevant genes was quantified in CLAD and transplant control tissues.The odds of BALF eosinophils being present was significantly higher at the time of acute rejection and non-rejection lung injury histologies and during pulmonary fungal detection. Early posttransplant ≥1% BALF eosinophils significantly and independently increased the risk for definite CLAD development (adjusted hazard ratio 2.04, p=0.009). Tissue expression of eotaxins, IL13 related genes, and the epithelial-derived cytokines IL33 and thymic stromal lymphoprotein were significantly increased in CLAD.BALF eosinophilia was an independent predictor of future CLAD risk across a multicenter lung recipient cohort. Additionally, type 2 inflammatory signals were induced in established CLAD. These data underscore the need for mechanistic and clinical studies to clarify the role of type 2 pathway-specific interventions in CLAD prevention or treatment.