The self-fulfilling prophecy of pulmonary fibrosis: a selective inspection of pathological signalling loops

Interstitial Lung Disease Associated with Systemic Sclerosis

Systemic sclerosis (SSc) is a rare autoimmune disease characterized by a tripod combining vasculopathy, fibrosis, and immune-mediated inflammatory processes. The prevalence of interstitial lung disease (ILD) in SSc varies according to the methods used to detect it, ranging from 25 to 95%. The fibrotic and vascular pulmonary manifestations of SSc, particularly ILD, are the main causes of morbidity and mortality, contributing to 35% of deaths. Although early trials were conducted with cyclophosphamide, more recent randomized controlled trials have been performed to assess the efficacy and tolerability of several medications, mostly mycophenolate, rituximab, tocilizumab, and nintedanib. Although many uncertainties remain, expert consensus is emerging to optimize the therapeutic management and to provide clinicians with evidence-based clinical practice guidelines for patients with SSc-ILD. This article provides an overview, in the light of the latest advances, of the available evidence for the diagnosis and management of SSc-ILD.

A Pharmacokinetic Study of Sixteen Major Bioactive Components of Jinshui-Huanxian Granules in Pulmonary Fibrosis Model and Control Rats Using Orbitrap Fusion Mass Spectrometry

Jinshui-Huanxian granules (JHGs), a Chinese herbal compound prescription, have shown a therapeutic effect in reducing lung tissue damage, improving the degree of pulmonary fibrosis, replenishing lungs and kidneys, relieving cough and asthma, reducing phlegm, and activating blood circulation. However, these active compounds' pharmacokinetics and metabolic processes were unclear. This study aimed to compare the pharmacokinetics, reveal the metabolic dynamic changes, and obtain the basic pharmacokinetic parameters of 16 main bioactive compounds after intragastric administration of JHGs in control and pulmonary fibrosis (PF) model rats by using Orbitrap Fusion MS. After administration of JHGs, the rat plasma was collected at different times. Pretreating the plasma sample with methanol and internal standard (IS) solution carbamazepine (CBZ), and it was then applied to a C18 column by setting gradient elution with a mobile phase consisting of methanol 0.1% formic acid aqueous solution. Detection was performed on an electrospray ionization source (ESI), and the scanning mode was SIM. Pharmacokinetic parameters were analyzed according to the different analytes' concentrations in plasma. The matrix effect was within the range of 79.01-110.90%, the extraction recovery rate was 80.37-102.72%, the intra-day and inter-day precision relative standard deviation (RSD) was less than 7.76%, and the stability was good, which met the requirements of biological sample testing. The method was validated (r ≥ 0.9955) and applied to compare the pharmacokinetic profiles of the control group and PF model group after intragastric administration of the JHGs. The 16 analytes exhibited different pharmacokinetic behaviors in vivo. In the pathological state of the PF model, most of the components were more favorable for metabolism and absorption, and it was more meaningful to study the pharmacokinetics. Above all, this study provided an essential reference for exploring the mechanism of action of JHGs and guided clinical medication as well.

Predictive investigation of idiopathic pulmonary fibrosis subtypes based on cellular senescence-related genes for disease treatment and management

Background: Idiopathic pulmonary fibrosis (IPF), a chronic, progressive lung disease characterized by interstitial remodeling and tissue destruction, affects people worldwide and places a great burden on society. Cellular senescence is thought to be involved in the mechanisms and development of IPF. The aim of this study was to predictively investigate subtypes of IPF according to cellular senescence-related genes and their correlation with the outcome of patients with IPF, providing possible treatment and management options for disease control. Methods: Gene expression profiles and follow-up data were obtained from the GEO database. Senescence-related genes were obtained from the CSGene database and analyzed their correlation with the outcome of IPF. A consensus cluster was constructed to classify the samples based on correlated genes. The GSVA and WGCNA packages in R were used to calculate the immune-related enriched fractions and construct gene expression modules, respectively. Metascape and the clusterProfiler package in R were used to enrich gene functions. The ConnectivityMap was used to probe suitable drugs for potential treatment. Results: A total of 99 cellular senescence-related genes were associated with IPF prognosis. Patients with IPF were divided into two subtypes with significant prognostic differences. Subtype S2 was characterized by enhanced fibrotic progression and infection, leading to acute exacerbation of IPF and poor prognosis. Finally, five cellular senescence-related genes, TYMS, HJURP, UBE2C, BIRC5, and KIF2C, were identified as potential biomarkers in poor prognostic patients with IPF. Conclusion: The study findings indicate that cellular senescence-related genes can be used to distinguish the prognosis of patients with IPF. Among them, five genes can be used as candidate biomarkers to predict patients with a poor prognostic subtype for which anti-fibrosis and anti-infection treatments could be suitable.

The Role of Nrf2 in Pulmonary Fibrosis: Molecular Mechanisms and Treatment Approaches

Pulmonary fibrosis is a chronic, progressive, incurable interstitial lung disease with high mortality after diagnosis and remains a global public health problem. Despite advances and breakthroughs in understanding the pathogenesis of pulmonary fibrosis, there are still no effective methods for the prevention and treatment of pulmonary fibrosis. The existing treatment options are imperfect, expensive, and have considerable limitations in effectiveness and safety. Hence, there is an urgent need to find novel therapeutic targets. The nuclear factor erythroid 2-related factor 2 (Nrf2) is a central regulator of cellular antioxidative responses, inflammation, and restoration of redox balance. Accumulating reports reveal that Nrf2 activators exhibit potent antifibrosis effects and significantly attenuate pulmonary fibrosis in vivo and in vitro. This review summarizes the current Nrf2-related knowledge about the regulatory mechanism and potential therapies in the process of pulmonary fibrosis. Nrf2 orchestrates the activation of multiple protective genes that target inflammation, oxidative stress, fibroblast–myofibroblast differentiation (FMD), and epithelial–mesenchymal transition (EMT), and the mechanisms involve Nrf2 and its downstream antioxidant, Nrf2/HO−1/NQO1, Nrf2/NOX4, and Nrf2/GSH signaling pathway. We hope to indicate potential for Nrf2 system as a therapeutic target for pulmonary fibrosis.

SAA1 is transcriptionally activated by STAT3 and accelerates renal interstitial fibrosis by inducing endoplasmic reticulum stress

Renal interstitial fibrosis (RIF) is the common irreversible pathway by which chronic kidney disease (CKD) progresses to the end stage. The transforming growth factor-β (TGF-β)/signal transducer and activator of transcription 3 (STAT3) signaling pathway is a common factor leading to inflammation-mediated RIF, but its downstream regulatory mechanism is still unclear. Bioinformatics analysis predicted that serum amyloid A protein 1 (SAA1) was one of the target genes for transcriptional activation of STAT3 signaling. As an acute phase reaction protein, SAA1 plays an important role in many inflammatory reactions, and research has suggested that SAA1 is significantly elevated in the serum of patients with CKD. In this research, multiple experiments were performed to investigate the role of SAA1 in the process of RIF. SAA1 was abnormally highly expressed in kidney tissue from individuals who underwent unilateral ureteral obstruction (UUO) and TGF-β-induced HK2 cells, and the abnormal expression was directly related to the transcriptional activation of STAT3. Additionally, SAA1 can directly target and bind valosin-containing protein (VCP)-interacting membrane selenoprotein (VIMP) to inhibit the function of the Derlin-1/VCP/VIMP complex, preventing the transportation and degradation of the misfolded protein, resulting in endoplasmic reticulum (ER) stress characterized by an increase in glucose-regulated protein 78 (GRP78) levels and ultimately promoting the occurrence and development of RIF.

Targeting Alveolar Repair in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is a fatal interstitial lung disease with limited therapeutic options. Current evidence suggests that IPF may be initiated by repeated epithelial injury in the distal lung followed by abnormal wound healing responses which occur due to intrinsic and extrinsic factors. Mechanisms contributing to chronic damage of the alveolar epithelium in IPF include dysregulated cellular processes such as apoptosis, senescence, abnormal activation of developmental pathways, aging, as well as genetic mutations. Therefore, targeting the regenerative capacity of the lung epithelium is an attractive approach in the development of novel therapies for IPF. Endogenous lung regeneration is a complex process involving coordinated cross-talk between multiple cell types and re-establishment of a normal extracellular matrix environment. This review will describe the current knowledge of reparative epithelial progenitor cells in the alveolar region of the lung and discuss potential novel therapeutic approaches for IPF focusing on endogenous alveolar repair. This article is open access and distributed under the terms of the Creative Commons Attribution Non-Commercial No Derivatives License 4.0 (http://creativecommons.org/licenses/by-nc-nd/4.0/).

Mechanical Feed-Forward Loops Contribute to Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis is a progressive scarring disease characterized by extracellular matrix accumulation and altered mechanical properties of lung tissue. Recent studies support the hypothesis that these compositional and mechanical changes create a progressive feed-forward loop in which enhanced matrix deposition and tissue stiffening contribute to fibroblast and myofibroblast differentiation and activation, which further perpetuates matrix production and stiffening. The biomechanical properties of tissues are sensed and responded to by mechanotransduction pathways that facilitate sensing of changes in mechanical cues by tissue resident cells and convert the mechanical signals into downstream biochemical signals. Although our understanding of mechanotransduction pathways associated with pulmonary fibrosis remains incomplete, recent progress has allowed us to begin to elucidate the specific mechanisms supporting fibrotic feed-forward loops. The mechanosensors discussed here include integrins, Piezo channels, transient receptor potential channels, and nonselective ion channels. Also discussed are downstream transcription factors, including myocardin-related transcription factor and Yes-associated protein/transcriptional coactivator with PDZ-binding motif. This review describes mechanosensors and mechanotransduction pathways associated with fibrosis progression and highlights promising therapeutic insights.