Differential Expression Of MiRNAs In Chronic Rhinosinusitis With And Without Nasal Polyps And Its Implication

PartⅠIdentification of differentially expressed miRNAs in chronicrhinosinusitis with and without nasal polypsBackground: Chronic rhinosinusitis (CRS) is one of the most frequently reportedchronic diseases. Although many causative factors have been implicated in pathogenesis ofCRS, the exact etiology of CRS is still far from completely revealed. MicroRNAs havebeen shown to be involved in various immunological events and several inflamatorydiseases. Therefore, our study was aimed to determine the miRNA expression profile inboth CRS with and without NPs and to identify differentially-expressed miRNAs.Methods: The miRNA array analysis was used to obtain miRNA expression profilingin both CRS with and without NPs. MicroRNA-125b and miR-26a were selected to validatethe array result by real-time PCR and in situ hybridization, which was based on literature.Results: Four miRNAs were up-regulated in CRS without NPs compared withcontrols, while 23miRNAs down-regulated. Seven miRNAs were increased in CRS withNPs compared with controls, while 69 miRNAs reduced. The enhanced level of miR-125bin CRS with NPs and reduced miR-26a were validated by real-time RT-PCR.MicroRNA-125b was expressed in BEAS-2B cells and sinasal epithelium, while theexpression of miR-26a was not detected in BEAS-2B cells.Conclusion: Differentially-expressed miRNAs were identified in CRS with andwithout NPs. The increased expression of miR-125b was associated with CRS with NPs. Afurther study of miR-125b may provide new clues to the pathogenesis of CRS with NPs. PartⅡThe impilcation of the enhanced expression of miR-125b innasal polypsBackground: MicroRNA-125b was demonstrated to be increased in CRS with NP inour previous study. The binding site of miR-125b with 4EBP1 was demonstrated bybioinformatics prediction. 4EBP1 was showed to have influence in I-IFN signaling. Thisstudy was designed to investigate whether 4EBP1 was a direct target of miR-125b and toexplore the the role of miR-125b in pathogenesis of CRS with NPs by regulating 4EBP1.Methods: The expression of 4EBP1 was assessed by means withimmunohistochemistry. Western blot was used to examine 4EBP1 level of BEAS-2B cellsuntreated.or transfected with mimic 125b and inhibitor. 4EBP13' UTR and its mutant wereinserted into luciferase report plasmid to contruct chimeric vectors. A luciferase reporterassays was performed to investigate direct effect of miR-125b on 4EBP1. IL-5 and IFN-βmRNA level were detected by using real time RT-PCR.Results: The 4EBP1 expression in sinonasal mucosa was significantly inhibited inCRS patients with NPs. Experimentally induced suppression or forced expression ofmiR-125b causes reciprocal alterations in protein expression of 4EBP1 in BEAS-2B cells.Moreover, a significant negative effect on luciferase activity was observed in BEAS-2Bcells con-transfected with construct bearing an intact miR-125b binding sites and mimicwhen compared with control. IL-5 and IFN-βmRNA were showed to be enhanced in CRSpatients with NPs compared with controls. IL-5 level inversely correlated with IFN-βexpression in sinonasal mucosa.Conclusion: 4EBP1 was a direct target of miR-125b. 4EBP1 may play a role insinasal epithelial immunity through modulating production of IFN-β, which was associatedwtih Th1/Th2 unbalance in CRS with NPs. MicroRNA-125b may be involved inpathogenesis of CRS with NPs by targeting 4EBP1.