In 2D versus 3D lung cultures, nintedanib and pirfenidone are found to decrease mesenchymal and epithelial fibrotic markers. A novel ex vivo method shows great potential to investigate important signaling pathways and mechanisms of early onset fibrosis for the identification of pro-fibrotic biomarkers.
Mareike Lehmann (Munich, Germany) analyzed the mode of action of nintedanib and pirfenidone, the only approved drugs known to decelerate disease progression, in ex vivo 3D lung-tissue cultures (3D-LTCs) derived from mice and humans. Both drugs decreased mesenchymal fibrotic genes in fibrotic 3D-LTCs and increased surfactant protein expression in these cultures.
Lehmann concluded, therefore, that 3D-LTCs represent a valuable tool to study the effects of antifibrotic drugs on epithelial cells and fibroblasts in the 3D system. Furthermore, nintedanib and pirfenidone were found to increase surfactant protein-C (SP-C) expression in 2D and 3D models in mouse and human systems.
Clinically relevant target genes
Christina Hesse (Hannover, Germany) used comparable techniques as performed in the previous presentation, this time to study the induction of pro-fibrotic biomarkers in precision-cut lung slices (PCLS). Human PCLS were cultured in the presence of TGF-β and TNF-α to induce a pro-fibrotic profile. Analysis of the mRNA profile revealed up-regulation of important pro-fibrotic genes in lungs from bleomycin-treated rats as compared with the controls. Extracellular matrix (ECM) genes, including metalloproteinases, were elevated in bleomycin-treated rat lungs as compared with control animals. A similar pattern of up-regulated genes was found in human PCLS that were stimulated with TGF-β and TNF-α.
Furthermore, the pro-inflammatory cytokine IL-1β, involved in the initial wound repair mechanism and early fibrotic response, was elevated on mRNA as well as protein level in TGF-β- and TNF-α-stimulated human PCLS. The mRNA pattern induced in PCLS therefore represents clinically relevant target genes. Ex vivo treatment with pharmacological interventions was found to be effective.
RNA expression profiles
miRNAs are small non-coding RNA molecules consisting of approximately 22 nucleotides that regulate gene expression. miRNA binding reduces gene expression by causing disruption of mRNA stability or translation. miRNA dysregulation can significantly influence cellular processes through repression of upregulation of single or multiple targets within the same pathway/process. The regulation and effects of miRNA are cell-specific. Drugs are being developed that can interfere with miRNA levels.
Besides cancer, a large number of pathologies are known to be influenced by miRNAs. For respiratory diseases, these include vascular remodelling, asthma, COPD, cystic fibrosis and idiopathic pulmonary fibrosis (IPF). Differentially expressed miRNAs regulate critical pathways in apoptosis, inflammation and fibrosis.
Several miRNAs have been reported to be dysregulated in IPF at different levels (tissue, plasma, and bronchoalveolar lavage), but in vivo histopathological correlations are scant. A study by Patrizia Morbini (Pavia, Italy) was aimed at identifying a profile of dysregulated miRNA specific for IPF. These results suggest that miR21 and miR34 overexpression is generally involved in fibrotic lung processes and are not specific for IPF, in accordance with the current view of IPF as the fibrotic outcome of injuries of different nature.
Germline mutations
Idiopathic interstitial pneumonia (IIP) is comprised of a heterogeneous group of rare lung parenchymal disorders, which are associated with high morbidity (e.g. increased frequency of lung cancer) and mortality. A genetic cause is identified in up to 20% of familial cases, in which mutations in telomerase and surfactant genes are the most common aetiologies.
Nadia Nathan (Paris, France) studied the pathophysiology of IIP and specifically the role of surfactant protein A (SP-A). In a French network for rare lung disease (RespiFIL), she explored the role of SFTPA1 mutations in IIP and lung cancer. In the 12 identified unrelated index cases, SFTPA1 W211R mutation is the first identified mutation of this gene and is associated with a high heterogeous phenotype. She advised that SFTPA1 and SFTPA2 mutations should be searched for in familial IIP/IPF with no telomerase mutation.
Source: Session 149: IPF pathogenesis. September 4th, 10:45-12:45, Room D Oral Presentation.
