Eduardo Montes-Martínez

Background: Idiopathic pulmonary fibrosis (IPF) is a chronic, progressive, and fatal interstitial lung disease characterized by excessive deposition of extracellular matrix and progressive destruction of the lung architecture. Repeated epithelial injury and aberrant tissue repair are strongly associated with its pathogenesis; however, the molecular mechanisms underlying disease progression remain incompletely understood. Altered microRNA (miRNA) expression has been extensively associated with IPF, but comparatively little attention has been given to the mechanisms regulating miRNA maturation and processing during pulmonary fibrosis. Objective: In this narrative review, we aimed to describe the relationship between IPF pathogenesis and alterations in miRNA maturation, with particular emphasis on post-transcriptional mechanisms that may disrupt the production and function of mature miRNAs. Methods: We conducted a narrative review of the available literature using PubMed, Scopus, and Google Scholar. No specific time frame was established because of the limited number of studies directly addressing miRNA maturation in IPF. Original research articles were prioritized, while relevant studies describing miRNA maturation mechanisms in other biological and disease contexts were also considered to provide mechanistic insight. Results: The available evidence suggests that alterations in miRNA maturation may contribute to miRNA dysregulation in IPF beyond changes in transcriptional control. Disruption of the Drosha/DGCR8 microprocessor complex, altered Dicer-dependent processing, and post-transcriptional modifications of miRNA precursors may affect the production of mature miRNAs. In addition, adenosine-to-inosine editing mediated by adenosine deaminases acting on RNA (ADARs) may modify miRNA sequences and influence their maturation, stability, and target selection. Mechanotransduction-associated pathways, including Hippo/YAP signaling, may further interfere with the miRNA-processing machinery. These alterations may contribute to the persistent dysregu-lation of antifibrotic miRNAs, including miR-29, thereby promoting extracellular matrix accumulation and sustaining profibrotic signaling. Conclusions: Although evidence directly linking defects in miRNA maturation to IPF remains limited, available findings support the hypothesis that alterations in post-transcriptional miRNA processing represent an additional regulatory layer contributing to pulmonary fibrosis. Further experimental studies are needed to determine how specific alterations in miRNA maturation and editing contribute to IPF pathogenesis and whether components of the miRNA-processing machinery may represent potential therapeutic targets.

Idiopathic pulmonary fibrosis (IPF) is a chronic, deathly disease with no recognized effective cure as yet. Furthermore, its diagnosis and differentiation from other diffuse interstitial diseases remain a challenge. Circulating miRNAs have been measured in IPF and have proven to be an adequate option as biomarkers for this disease. These miRNAs, released into the circulation outside the cell through exosomes and proteins, play a crucial role in the pathogenic pathways and mechanisms involved in IPF development. This review focuses on the serum/plasma miRNAs reported in IPF that have been validated by real-time PCR and the published evidence regarding the fibrotic process. First, we describe the mechanisms by which miRNAs travel through the circulation (contained in exosomes and bound to proteins), as well as the mechanism by which miRNAs perform their function within the cell. Subsequently, we summarize the evidence concerning miRNAs reported in serum/plasma, where we find contradictory functions in some miRNAs (dual functions in IPF) when comparing the findings in vitro vs. in vivo. The most relevant finding, for instance, the levels of miRNAs let-7d and miR-21 reported in the serum/plasma in IPF, correspond to those found in studies in lung fibroblasts and the murine bleomycin model, reinforcing the usefulness of these miRNAs as future biomarkers in IPF.

Idiopathic pulmonary fibrosis, a chronic and fatal condition with no effective cure, is a challenging disease within the group of interstitial lung diseases. The pathogenic mechanisms of this disease are still not fully understood. In this context, the research on miRNAs, which are small non-coding RNAs that regulate messenger RNAs, is of utmost importance. These miRNAs, released into the circulation outside the cell through exosomes, play a crucial role in the pathogenic pathways and mechanisms involved in IPF development. The analysis of miRNAs in the serum/plasma of IPF patients has opened up new possibilities in the search for biomarkers. This review focuses on circulating miRNAs validated by real-time PCR in IPF and the evidence reported about the pulmonary fibrotic process.

Communication between neighboring or distant cells is made through a complex network that includes extracellular vesicles (EVs). Exosomes, which are a subgroup of EVs, are released from most cell types and have been found in biological fluids such as urine, plasma, and airway secretions like bronchoalveolar lavage (BAL), nasal lavage, saliva, and sputum. Mainly, the cargo exosomes are enriched with mRNAs and microRNAs (miRNAs), which can be transferred to a recipient cell consequently modifying and redirecting its biological function. The effects of miRNAs derive from their role as gene expression regulators by repressing or degrading their target mRNAs. Nowadays, various types of research are focused on evaluating the potential of exosomal miRNAs as biomarkers for the prognosis and diagnosis of different pathologies. Nevertheless, there are few reports on their role in the pathophysiology of idiopathic pulmonary fibrosis (IPF), a chronic lung disease characterized by progressive lung scarring with no cure. In this review, we focus on the role and effect of exosomal miRNAs as intercellular communicators in the onset and progression of IPF, as well as discussing their potential utility as therapeutic agents for the treatment of this disease.

Double-stranded RNA adenosine deaminase 1 (ADAR1) is significantly down-regulated in fibroblasts derived from Idiopathic Pulmonary Fibrosis (IPF) patients, and its overexpression restored levels of miRNA-21, PELI1, and SPRY2. There are two ADAR1 isoforms in humans, ADAR1-p110 and ADAR1-p150, generated by an alternative promoter. Let-7d is considered an essential microRNA in Pulmonary Fibrosis (PF). In silico analysis revealed COL3A1 and SMAD2, proteins involved in the development of IPF, as Let-7d targets. We analyzed the role of ADAR1-p110 and ADAR1-p150 isoforms in the regulation of Let-7d maturation and the effect of this regulation on the expression of COL3A1 and SMAD2 in IPF fibroblast. We demonstrated that differential expression and subcellular distribution of ADAR1 isoforms in fibroblasts contribute to the up-regulation of pri-miR-Let-7d and down-regulation of mature Let-7d. Induction of overexpression of ADAR1 reestablishes the expression of pri-miR-Let-7d and Let-7d in lung fibroblasts. The reduction of mature Let-7d upregulates the expression of COL3A1 and SMAD2. Thus, ADAR1 isoforms and Let-7d could have a synergistic role in IPF, which is a promising explanation in the mechanisms of fibrosis development, and the regulation of both molecules could be used as a therapeutic approach in IPF.

In spite of a current increasing trend in the development of miniaturized, standalone point-of-care (PoC) biosensing platforms in the literature, the actual implementation of such systems in the field is far from being a reality although deeply needed. In the particular case of the population screenings for local or regional diseases related to specific pathogens, the diagnosis of the presence of specific antibodies could drastically modify therapies and even the organization of public policies. The aim of this work was to develop a fast, cost-effective detection method based on the manipulation of functionalized magnetic beads for an efficient diagnosis of hypersensitivity pneumonitis (HP), looking for the presence of anti-pigeon antigen antibodies (APAA) in a patient’s serum. We presented a Diagnostic Biosensor Method (DBM) in detail, with validation by comparison with a traditional high-throughput platform (ELISA assay). We also demonstrated that it was compatible with a microfluidic chip that could be eventually incorporated into a PoC for easy and broad deployment using portable optical detectors. After standardization of the different reaction steps, we constructed and validated a plastic chip that could easily be scaled to high-volume manufacturing in the future. The solution proved comparable to conventional ELISA assays traditionally performed by the clinicians in their laboratory and should be compatible with other antibody detection directly from patient samples.