miR-200 family members reduce senescence and restore idiopathic pulmonary fibrosis type II alveolar epithelial cell transdifferentiation

Abstract

RationaleAlveolar type II (ATII) cells act as adult stem cells contributing to alveolar type I (ATI) cell renewal and play a major role in idiopathic pulmonary fibrosis (IPF), as supported by familial cases harbouring mutations in genes specifically expressed by these cells. During IPF, ATII cells lose their regenerative potential and aberrantly express pathways contributing to epithelial–mesenchymal transition (EMT). The microRNA miR-200 family is downregulated in IPF, but its effect on human IPF ATII cells remains unproven. We wanted to 1) evaluate the characteristics and transdifferentiating ability of IPF ATII cells, and 2) test whether miR-200 family members can rescue the regenerative potential of fibrotic ATII cells.MethodsATII cells were isolated from control or IPF lungs and cultured in conditions promoting their transdifferentiation into ATI cells. Cells were either phenotypically monitored over time or transfected with miR-200 family members to evaluate the microRNA effect on the expression of transdifferentiation, senescence and EMT markers.ResultsIPF ATII cells show a senescent phenotype (p16 and p21), overexpression of EMT (ZEB1/2) and impaired expression of ATI cell markers (AQP5 and HOPX) after 6 days of culture in differentiating medium. Transfection with certain miR-200 family members (particularly miR-200b-3p and miR-200c-3p) reduced senescence marker expression and restored the ability to transdifferentiate into ATI cells.ConclusionsWe demonstrated that ATII cells from IPF patients express senescence and EMT markers, and display a reduced ability to transdifferentiate into ATI cells. Transfection with certain miR-200 family members rescues this phenotype, reducing senescence and restoring transdifferentiation marker expression.

Epithelial–Mesenchymal Transition: A Major Pathogenic Driver in Idiopathic Pulmonary Fibrosis?

“…The sum of this evidence supports the new interpretative key for IPF pathogenesis that has emerged in recent years: ATII stemness failure, as a consequence of the ATII-to-ATI trans-differentiation blockade, seems to be responsible for the hyperactivation of ATII cells and the upregulation of several upstream pathways that are major drivers of EMT, besides directly stimulating fibroblast proliferation and collagen secretion in a paracrine fashion [8].…”

Non-coding RNAs as Regulators of Cellular Senescence in Idiopathic Pulmonary Fibrosis and Chronic Obstructive Pulmonary Disease

“…Transfection of AECs with miR-200a and miR-141 reduces epithelial mesenchymal transition (EMT) and the expression of cellular senescence markers including p16 and p21, but does not improve AEC proliferation capacity. In contrast, transfection with miR-200b/c increases differentiation of senescent type II AECs into type I AECs, decreases EMT, and reduces disease severity in animal models of pulmonary fibrosis ( 142 – 145 ).…”

Role of various imbalances centered on alveolar epithelial cell/fibroblast apoptosis imbalance in the pathogenesis of idiopathic pulmonary fibrosis

“…miRNAs are short (∼22 nt) single-stranded ribonucleic acids functioning as post-transcriptional regulators of gene expression that play important roles by binding to specific sequences, blocking translation, or causing degradation of the target mRNA, which results in gene silencing. Through various mechanisms, some miRNAs (eg, miR-21, [ 55 , 56 ] miR-31, [ 57 ] miR-145, [ 58 ] miR-154, [ 59 ] and miR-199a [ 60 ] ) play a role in promoting fibrosis during the pathogenesis of IPF, and their expression levels are often elevated, while others (such as let-7d, [ 56 , 61 ] miR-9, [ 62 ] miR-18a, [ 63 ] miR-26a, [ 56 ] miR-27b, [ 64 ] miR-29, [ 65 ] miR-30a, [ 56 , 66 ] miR-155, [ 67 ] miR-200, [ 68 ] miR-221, [ 69 ] miR-323a, [ 70 ] miR-326, [ 71 ] miR-338, [ 72 ] miR-375, [ 73 ] and miR-486 [ 74 ] ) prevent fibrosis, and their expression levels are reduced. One recent study demonstrated that the long-intervening non-coding RNAs (lincRNAs) LINC00960 and LINC01140 can regulate fibroblast proliferation and inflammation, while changes in LINC01140 expression may mediate a reduced inflammatory response in IPF fibroblasts.…”