MiRNAs-Directed Signaling in Lung Transplantation Reveals Differential Transcription Factors Expression in Acute or Chronic Lung Dysfunction

Abstract

In a previous study on miRNA profiling in bronchoalveolar lavage (BAL) fluid of lung transplanted (LTx) patients we obtained signatures of deregulated miRNAs associated to acute lung allograft dysfunction (ALAD). Now we extended this analysis to chronic dysfunction (CLAD) and to pathways potentially modulated by AR- or CLAD-miRNAs. BALs were obtained from 16 patients who underwent bilateral LTx at our Institution. Mean follow-up time was 21 months (range 17-25). MiRNAs expression in BAL samples collected 7 days (T0), 15 days (T1) and 3 months (T2) after LTx was analyzed using TLDA. The association of miRNAs with pneumonia, acute rejection (AR) or CLAD was examined using ANOVA or Cox regression. The false discovery rate was applied for multiple comparison correction. miRNAs targets were search with miRTarget Link and imported in STRING or WebGestalt databases for functional annotation. Potential targets expression was analyzed by immunohistochemistry (IHC) on transbrochial biopsies. We identified one, 9 and 4 BAL-miRNAs whose upregulation is associated with pneumonia, AR or CLAD respectively (Fig. 1A-C). At T1, six BAL-miRNAs predicted CLAD by Cox model. Pathways prediction revealed that AR- or CLAD-miRNAs regulated cell dedifferentiation or WNT signaling, respectively, through the modulation of Sp1 or Bcl2 and cMYC factors (Fig. 1D,E). By IHC, Sp1 was more expressed in biopsies from patients with AR (Fig. 1F) whereas Bcl2 was predominantly detected in lungs from patients with CLAD (Fig. 1G). Our results, although preliminary, uncover novel miRNAs-networks involved in AR and CLAD pathogenesis.