Studying the Correlation between Neutrophils and miR21 Expression: Role in Bronchiolitis Obliterans Syndrome

Purpose Bronchiolitis obliterans syndrome (BOS) is associated with poor long-term survival. In its pathogenesis neutrophils (NEU) are recognized as relevant players. Moreover, our group has recently showed that some microRNAs (miRs) may act as pro-fibrotic effectors in the context of BOS highlighting the role of miR21, whose expression was higher in BOS lungs respective to healthy lungs. Our aim was to assess whether activated NEU might contribute to epithelial mesenchymal transition (EMT) through the up regulation of miR21 in lung cells. Methods As in vitro models we chose A549 cell lines. We co-coltured for 72h cell lines with different conditions: NEU previously activated (NEU+); Supernatant of NEU previously activated with PMA - (SUP+); Neutrophil Elastase (NE); NEU+ / alpha-1-antitrypsin (AAT); SUP+ /AAT; NE / AAT and TGF-β as positive control. Total RNAs from treated cells was extracted and miR21 expressions were assessed by RT-PCR (using U6 as reference gene). Results We observed that all conditions induced significant miR21 up-regulation in both cell lines in contrast to untreated cells (p Conclusion These results light new interest on a molecular mechanism underlying BOS development, and, if further confirmed suggests a possible therapeutic strategy aimed to modulate NEU in lung transplant patients using AAT.