Transglutaminase 2 knockout mice are protected from bleomycin-induced lung fibrosis with preserved lung function and reduced metabolic derangements.

Pulmonary fibrosis is an interstitial scarring disease of the lung characterized by poor prognosis and limited treatment options. Tissue transglutaminase 2 (TG2) is believed to promote lung fibrosis by crosslinking extracellular matrix components and activating latent TGFß. This study assessed physiologic pulmonary function and metabolic alterations in the mouse bleomycin model with TG2 genetic deletion. TG2-deficient mice demonstrated attenuated the fibrosis and preservation of lung function, with significant reduction in elastance and increases in compliance and inspiratory capacity compared to control mice treated with bleomycin. Bleomycin induced metabolic changes in the mouse lung that were consistent with increased aerobic glycolysis, including increased expression of lactate dehydrogenase A and increased production of lactate, as well as increased glutamine, glutamate, and aspartate. TG2-deficient mice treated with bleomycin exhibited similar metabolic changes but with reduced magnitude. Our results demonstrate that TG2 is required for a typical fibrosis response to injury. In the absence of TG2, the fibrotic response is biochemically similar to wild-type, but lesions are smaller and lung function is preserved. We also show for the first time that profibrotic pathways of tissue stiffening and metabolic reprogramming are interconnected, and that metabolic disruptions in fibrosis go beyond glycolysis.

Biogenesis and Function of circRNAs in Pulmonary Fibrosis.

Pulmonary fibrosis is a class of fibrosing interstitial lung diseases caused by many pathogenic factors inside and outside the lung, with unknown mechanisms and without effective treatment. Therefore, a comprehensive understanding of the molecular mechanism implicated in pulmonary fibrosis pathogenesis is urgently needed to develop new and effective measures. Although circRNAs have been widely acknowledged as new contributors to the occurrence and development of diseases, only a small number of circRNAs have been functionally characterized in pulmonary fibrosis. Here, we systematically review the biogenesis and functions of circRNAs and focus on how circRNAs participate in pulmonary fibrogenesis by influencing various cell fates. Meanwhile, we analyze the current exploration of circRNAs as a diagnostic biomarker, vaccine, and therapeutic target in pulmonary fibrosis and objectively discuss the challenges of circRNA- based therapy for pulmonary fibrosis. We hope that the review of the implication of circRNAs will provide new insights into the development circRNA-based approaches to treat pulmonary fibrosis.

RNA-sequencing reveals differential fibroblast responses to bleomycin and pneumonectomy.

Pulmonary fibrosis is characterized by pathological accumulation of scar tissue in the lung parenchyma. Many of the processes that are implicated in fibrosis, including increased extracellular matrix synthesis, also occur following pneumonectomy (PNX), but PNX instead results in regenerative compensatory growth of the lung. As fibroblasts are the major cell type responsible for extracellular matrix production, we hypothesized that comparing fibroblast responses to PNX and bleomycin (BLM) would unveil key differences in the role they play during regenerative versus fibrotic lung responses. RNA-sequencing was performed on flow-sorted fibroblasts freshly isolated from mouse lungs 14 days after BLM, PNX, or sham controls. RNA-sequencing analysis revealed highly similar biological processes to be involved in fibroblast responses to both BLM and PNX, including TGF-ß1 and TNF-α. Interestingly, we observed smaller changes in gene expression after PNX than BLM at Day 14, suggesting that the fibroblast response to PNX may be muted by expression of transcripts that moderate pro-fibrotic pathways. Itpkc, encoding inositol triphosphate kinase C, was a gene uniquely up-regulated by PNX and not BLM. ITPKC overexpression in lung fibroblasts antagonized the pro-fibrotic effect of TGF-ß1. RNA-sequencing analysis has identified considerable overlap in transcriptional changes between fibroblasts following PNX and those overexpressing ITPKC.

Mechanism of action of miR-15a-5p and miR-152-3p in paraquat-induced pulmonary fibrosis through Wnt/ß-catenin signaling mediation.

Background: miRNAs are small, conserved, single-stranded non-coding RNA that are typically transported by exosomes for their functional roles. The therapeutic potential of exosomal miRNAs has been explored in various diseases including breast cancer, pancreatic cancer, cholangiocarcinoma, skin diseases, Alzheimer's disease, stroke, and glioma. Pathophysiological processes such as cellular inflammation, apoptosis, necrosis, immune dysfunction, and oxidative stress are closely associated with miRNAs. Internal and external factors such as tissue ischemia, hypoxia, pathogen infection, and endotoxin exposure can trigger these reactions and are linked to miRNAs. Paraquat-induced fibrosis is a protracted process that may not manifest immediately after injury but develops during bodily recovery, providing insights into potential miRNA intervention treatments. Rationale: These findings could potentially be applied for further pharmaceutical research and clinical therapy of paraquat-induced pulmonary fibrosis, and are likely to be of great interest to clinicians involved in lung fibrosis research. Methodology: Through a literature review, we identified an association between miR-15a-5p and miR-152-3p and their involvement in the Wnt signaling pathway. This allowed us to deduce the molecular mechanisms underlying regulatory interactions involved in paraquat-induced lung fibrosis. Results: miR-15a-5p and miR-152-3p play roles in body repair processes, and pulmonary fibrosis can be considered a form of reparative response by the body. Although the initial purpose of fibrotic repair is to restore normal body function, excessive tissue fibrosis, unlike scar formation following external skin trauma, can significantly and adversely affect the body. Modulating the Wnt/ß-catenin signaling pathway is beneficial in alleviating tissue fibrosis in various diseases. Conclusions: In this study, we delineate the association between miR-15a-5p and miR-152-3p and the Wnt/ß-catenin signaling pathway, presenting a novel concept for addressing paraquat-induced pulmonary fibrosis.

Metabolomic insights into pulmonary fibrosis: a mendelian randomization study.

BACKGROUND: This study leverages a two-sample Mendelian Randomization (MR) approach to explore the causal relationships between 1,400 metabolites and pulmonary fibrosis, using genetic variation as instrumental variables. By adhering to stringent criteria for instrumental variable selection, the research aims to uncover metabolic pathways that may influence the risk and progression of pulmonary fibrosis, providing insights into potential therapeutic targets. METHODS: Utilizing data from the OpenGWAS project, which includes a significant European cohort, and metabolite GWAS data from the Canadian Longitudinal Aging Study (CLSA), the study employs advanced statistical methods. These include inverse variance weighting (IVW), weighted median estimations, and comprehensive sensitivity analyses conducted using the R software environment to ensure the robustness of the causal inferences. RESULTS: The study identified 62 metabolites with significant causal relationships with pulmonary fibrosis, highlighting both risk-enhancing and protective metabolic factors. This extensive list of metabolites presents a broad spectrum of potential therapeutic targets and biomarkers for early detection, underscoring the metabolic complexity underlying pulmonary fibrosis. CONCLUSIONS: The findings from this MR study significantly advance our understanding of the metabolic underpinnings of pulmonary fibrosis, suggesting that alterations in specific metabolites could influence the risk and progression of the disease. These insights pave the way for the development of novel diagnostic and therapeutic strategies, emphasizing the potential of metabolic modulation in managing pulmonary fibrosis.

Lung injury-induced activated endothelial cell states persist in aging-associated progressive fibrosis.

Progressive lung fibrosis is associated with poorly understood aging-related endothelial cell dysfunction. To gain insight into endothelial cell alterations in lung fibrosis we performed single cell RNA-sequencing of bleomycin-injured lungs from young and aged mice. Analysis reveals activated cell states enriched for hypoxia, glycolysis and YAP/TAZ activity in ACKR1+ venous and TrkB+ capillary endothelial cells. Endothelial cell activation is prevalent in lungs of aged mice and can also be detected in human fibrotic lungs. Longitudinal single cell RNA-sequencing combined with lineage tracing demonstrate that endothelial activation resolves in young mouse lungs but persists in aged ones, indicating a failure of the aged vasculature to return to quiescence. Genes associated with activated lung endothelial cells states in vivo can be induced in vitro by activating YAP/TAZ. YAP/TAZ also cooperate with BDNF, a TrkB ligand that is reduced in fibrotic lungs, to promote capillary morphogenesis. These findings offer insights into aging-related lung endothelial cell dysfunction that may contribute to defective lung injury repair and persistent fibrosis.

Deregulated immune cell recruitment orchestrated by c-MET impairs pulmonary inflammation and fibrosis.

BACKGROUND: Pulmonary fibrosis (PF) represents the pathologic end stage of several interstitial lung diseases (ILDs) associated with high morbidity and mortality rates. However, current treatments can only delay disease progression rather than provide a cure. The role of inflammation in PF progression is well-established, but new insights into immune regulation are fundamental for developing more efficient therapies. c-MET signaling has been implicated in the migratory capacity and effector functions of immune cells. Nevertheless, the role of this signaling pathway in the context of PF-associated lung diseases remains unexplored. METHODS: To determine the influence of c-MET in immune cells in the progression of pulmonary fibrosis, we used a conditional deletion of c-Met in immune cells. To induce pulmonary fibrosis mice were administered with bleomycin (BLM) intratracheally. Over the course of 21 days, mice were assessed for weight change, and after euthanasia at different timepoints, bronchoalveolar lavage fluid cells and lung tissue were assessed for inflammation and fibrosis. Furthermore, c-MET expression was assessed in cryobiopsy sections, bronchoalveolar lavage fluid cells samples and single cell RNA-sequencing dataset from human patients with distinct interstitial lung diseases. RESULTS: c-MET expression was induced in lung immune cells, specifically in T cells, interstitial macrophages, and neutrophils, during the inflammatory phase of BLM-induced PF mouse model. Deletion of c-Met in immune cells correlated with earlier weight recovery and improved survival of BLM-treated mice. Moreover, the deletion of c-Met in immune cells was associated with early recruitment of the immune cell populations, normally found to express c-MET, leading to a subsequent attenuation of the cytotoxic and proinflammatory environment. Consequently, the less extensive inflammatory response, possibly coupled with tissue repair, culminated in less exacerbated fibrotic lesions. Furthermore, c-MET expression was up-regulated in lung T cells from patients with fibrosing ILD, suggesting a potential involvement of c-MET in the development of fibrosing disease. CONCLUSIONS: These results highlight the critical contribution of c-MET signaling in immune cells to their enhanced uncontrolled recruitment and activation toward a proinflammatory and profibrotic phenotype, leading to the exacerbation of lung injury and consequent development of fibrosis.

Integrated mRNA-miRNA transcriptome profiling of blood immune responses potentially related to pulmonary fibrosis in forest musk deer.

Background: Forest musk deer (FMD, Moschus Berezovskii) is a critically endangered species world-widely, the death of which can be caused by pulmonary disease in the farm. Pulmonary fibrosis (PF) was a huge threat to the health and survival of captive FMD. MicroRNAs (miRNAs) and messenger RNAs (mRNAs) have been involved in the regulation of immune genes and disease development. However, the regulatory profiles of mRNAs and miRNAs involved in immune regulation of FMD are unclear. Methods: In this study, mRNA-seq and miRNA-seq in blood were performed to constructed coexpression regulatory networks between PF and healthy groups of FMD. The hub immune- and apoptosis-related genes in the PF blood of FMD were explored through Gene Ontology (GO) and the Kyoto Encyclopedia of Genes and Genomes (KEGG) enrichment analysis. Further, protein-protein interaction (PPI) network of immune-associated and apoptosis-associated key signaling pathways were constructed based on mRNA-miRNA in the PF blood of the FMD. Immune hub DEGs and immune hub DEmiRNAs were selected for experimental verification using RT-qPCR. Results: A total of 2744 differentially expressed genes (DEGs) and 356 differentially expressed miRNAs (DEmiRNAs) were identified in the PF blood group compared to the healthy blood group. Among them, 42 DEmiRNAs were negatively correlated with 20 immune DEGs from a total of 57 correlations. The DEGs were significantly associated with pathways related to CD molecules, immune disease, immune system, cytokine receptors, T cell receptor signaling pathway, Th1 and Th2 cell differentiation, cytokine-cytokine receptor interaction, intestinal immune network for IgA production, and NOD-like receptor signaling pathway. There were 240 immune-related DEGs, in which 186 immune-related DEGs were up-regulated and 54 immune-related DEGs were down-regulated. In the protein-protein interaction (PPI) analysis of immune-related signaling pathway, TYK2, TLR2, TLR4, IL18, CSF1, CXCL13, LCK, ITGB2, PIK3CB, HCK, CD40, CD86, CCL3, CCR7, IL2RA, TLR3, and IL4R were identified as the hub immune genes. The mRNA-miRNA coregulation analysis showed that let-7d, miR-324-3p, miR-760, miR-185, miR-149, miR-149-5p, and miR-1842-5p are key miRNAs that target DEGs involved in immune disease, immune system and immunoregulation. Conclusion: The development and occurrence of PF were significantly influenced by the immune-related and apoptosis-related genes present in PF blood. mRNAs and miRNAs associated with the development and occurrence of PF in the FMD.

IQGAP1 Regulates Actin Polymerization and Contributes to Bleomycin-Induced Lung Fibrosis.

We previously found IQ motif containing GTPase activating protein (IQGAP1) to be consistently elevated in lung fibroblasts (LF) isolated from patients with scleroderma (systemic sclerosis, SSc)-associated interstitial lung disease (ILD) and reported that IQGAP1 contributed to SSc by regulating expression and organization of α-smooth muscle actin (SMA) in LF. The aim of this study was to compare the development of ILD in the presence and absence of IQGAP1. Pulmonary fibrosis was induced in IQGAP1 knockout (KO) and wild-type (WT) mice by a single-intratracheal instillation of bleomycin. Two and three weeks later, mice were euthanized and investigated. We observed that the IQGAP1 KO mouse was characterized by a reduced rate of actin polymerization with reduced accumulation of actin in the lung compared to the WT mouse. After exposure to bleomycin, the IQGAP1 KO mouse demonstrated decreased contractile activity of LF, reduced expression of SMA, TGFß, and collagen, and lowered overall fibrosis scores compared to the WT mouse. The numbers of inflammatory cells and expression of pro-inflammatory cytokines in lung tissue were not significantly different between IQGAP1 KO and WT mice. We conclude that IQGAP1 plays an important role in the development of lung fibrosis induced by bleomycin, and the absence of IQGAP1 reduces the contractile activity of lung fibroblast and bleomycin-induced pulmonary fibrosis. Thus, IQGAP1 may be a potential target for novel anti-fibrotic therapies for lung fibrosis.

BACH1 transcriptionally upregulates FOSL2 to induce M2 macrophages phenotype by activating TGFß/SMAD signaling to promote the transformation of lung fibroblasts into myofibroblasts.

Pulmonary fibrosis is a chronic and progressive lung disorder. The pro-fibrosis factors induced by M2 macrophage phenotype promote the differentiation of fibroblasts into myofibroblasts, which is essential for pulmonary fibrosis. We aimed to explore the role and mechanism of BTB domain and CNC homology 1 (BACH1) in pulmonary fibrosis. BACH1 was knocked down in THP-1 polarized M2 macrophages with or without FOS-like antigen 2 (FOSL2) overexpression, the expression of M2 macrophage markers was detected. Cell viability, migration, invasion and extracellular matrix (ECM) accumulation were estimated by CCK-8, wound healing, transwell, western bot and immunofluorescence staining. Luciferase reporter and chromatin immunoprecipitation assays were used to verify the binding of BACH1 to FOSL2 promotor region. In vivo, a bleomycin (BLM)-induced pulmonary fibrosis mice model was established to evaluate the effect of BACH1 silencing on the histopathological changes, M2 macrophage phenotype and extracellular matrix (ECM) deposition. Expression of proteins was assessed with western blot. Results indicated that BACH1 expression was upregulated in M2 macrophages polarized from THP-1 cells. BACH1 deficiency inhibited the polarization of THP-1 to the M2 macrophage phenotype to promote the transformation of lung fibroblasts into myofibroblasts. Additionally, BACH1 could transcriptionally activate FOSL2 expression in THP-1-derived macrophages to upregulate TGFß/SMAD signaling in HFL-1 cells. The animal experiments indicated that BACH1 knockdown alleviated BLM-induced pulmonary fibrosis, M2 macrophage polarization and inactivated FOSL2/TGFß/SMAD signaling in mice lung tissues. Together, this finding suggests BACH1/FOSL2 may be useful therapeutic targets for the treatment of pulmonary fibrosis.

A roadmap to precision treatments for familial pulmonary fibrosis.

Interstitial lung diseases (ILDs) in adults and children (chILD) are a heterogeneous group of lung disorders leading to inflammation, abnormal tissue repair and scarring of the lung parenchyma often resulting in respiratory failure and death. Inherited factors directly cause, or contribute significantly to the risk of developing ILD, so called familial pulmonary fibrosis (FPF), and monogenic forms may have a poor prognosis and respond poorly to current treatments. Specific, variant-targeted or precision treatments are lacking. Clinical trials of repurposed drugs, anti-fibrotic medications and specific treatments are emerging but for many patients no interventions exist. We convened an expert working group to develop an overarching framework to address the existing research gaps in basic, translational, and clinical research and identified areas for future development of preclinical models, candidate medications and innovative clinical trials. In this Position Paper, we summarise working group discussions, recommendations, and unresolved questions concerning precision treatments for FPF.

Downregulation of HMGCS2 mediated AECIIs lipid metabolic alteration promotes pulmonary fibrosis by activating fibroblasts.

BACKGROUND: Abnormal lipid metabolism has recently been reported as a crucial signature of idiopathic pulmonary fibrosis (IPF). However, the origin and biological function of the lipid and possible mechanisms of increased lipid content in the pathogenesis of IPF remains undetermined. METHODS: Oil-red staining and immunofluorescence analysis were used to detect lipid accumulation in mouse lung fibrosis frozen sections, Bleomycin-treated human type II alveolar epithelial cells (AECIIs) and lung fibroblast. Untargeted Lipid omics analysis was applied to investigate differential lipid species and identified LysoPC was utilized to treat human lung fibroblasts and mice. Microarray and single-cell RNA expression data sets identified lipid metabolism-related differentially expressed genes. Gain of function experiment was used to study the function of 3-hydroxy-3-methylglutaryl-Coa Synthase 2 (HMGCS2) in regulating AECIIs lipid metabolism. Mice with AECII-HMGCS2 high were established by intratracheally delivering HBAAV2/6-SFTPC- HMGCS2 adeno-associated virus. Western blot, Co-immunoprecipitation, immunofluorescence, site-directed mutation and flow cytometry were utilized to investigate the mechanisms of HMGCS2-mediated lipid metabolism in AECIIs. RESULTS: Injured AECIIs were the primary source of accumulated lipids in response to Bleomycin stimulation. LysoPCs released by injured AECIIs could activate lung fibroblasts, thus promoting the progression of pulmonary fibrosis. Mechanistically, HMGCS2 was decreased explicitly in AECIIs and ectopic expression of HMGCS2 in AECIIs using the AAV system significantly alleviated experimental mouse lung fibrosis progression via modulating lipid degradation in AECIIs through promoting CPT1A and CPT2 expression by interacting with PPARα. CONCLUSIONS: These data unveiled a novel etiological mechanism of HMGCS2-mediated AECII lipid metabolism in the genesis and development of pulmonary fibrosis and provided a novel target for clinical intervention.

Transcriptional Changes in Radiation-Induced Lung Injury: A Comparative Analysis of Two Radiation Doses for Preclinical Research.

In a recent stereotactic body radiation therapy animal model, radiation pneumonitis and radiation pulmonary fibrosis were observed at around 2 and 6 weeks, respectively. However, the molecular signature of this model remains unclear. This study aimed to examine the molecular characteristics at these two stages using RNA-seq analysis. Transcriptomic profiling revealed distinct transcriptional patterns for each stage. Inflammatory response and immune cell activation were involved in both stages. Cell cycle processes and response to type II interferons were observed during the inflammation stage. Extracellular matrix organization and immunoglobulin production were noted during the fibrosis stage. To investigate the impact of a 10 Gy difference on fibrosis progression, doses of 45, 55, and 65 Gy were tested. A dose of 65 Gy was selected and compared with 75 Gy. The 65 Gy dose induced inflammation and fibrosis as well as the 75 Gy dose, but with reduced lung damage, fewer inflammatory cells, and decreased collagen deposition, particularly during the inflammation stage. Transcriptomic analysis revealed significant overlap, but differences were observed and clarified in Gene Ontology and KEGG pathway analysis, potentially influenced by changes in interferon-gamma-mediated lipid metabolism. This suggests the suitability of 65 Gy for future preclinical basic and pharmaceutical research connected with radiation-induced lung injury.

Loss of ZNF451 mediates fibroblast activation and promotes lung fibrosis.

BACKGROUND: No effective therapies for pulmonary fibrosis (PF) exist because of the unclear molecular pathogenesis and the lack of effective therapeutic targets. Zinc finger protein 451 (ZNF451), a transcriptional regulator, plays crucial roles in the pathogenesis of several diseases. However, its expression pattern and function in PF remain unknown. This study was designed to investigate the role of ZNF451 in the pathogenesis of lung fibrosis. METHODS: GEO dataset analysis, RT‒PCR, and immunoblot assays were used to examine the expression of ZNF451 in PF; ZNF451 knockout mice and ZNF451-overexpressing lentivirus were used to determine the importance of ZNF451 in PF progression; and migration assays, immunofluorescence staining, and RNA-seq analysis were used for mechanistic studies. RESULTS: ZNF451 is downregulated and negatively associated with disease severity in PF. Compared with wild-type (WT) mice, ZNF451 knockout mice exhibited much more serious PF changes. However, ZNF451 overexpression protects mice from BLM-induced pulmonary fibrosis. Mechanistically, ZNF451 downregulation triggers fibroblast activation by increasing the expression of PDGFB and subsequently activating PI3K/Akt signaling. CONCLUSION: These findings uncover a critical role of ZNF451 in PF progression and introduce a novel regulatory mechanism of ZNF451 in fibroblast activation. Our study suggests that ZNF451 serves as a potential therapeutic target for PF and that strategies aimed at increasing ZNF451 expression may be promising therapeutic approaches for PF.

Curcumin regulates pulmonary extracellular matrix remodeling and mitochondrial function to attenuate pulmonary fibrosis by regulating the miR-29a-3p/DNMT3A axis.

Epigenetic regulation and mitochondrial dysfunction are essential to the progression of idiopathic pulmonary fibrosis (IPF). Curcumin (CCM) in inhibits the progression of pulmonary fibrosis by regulating the expression of specific miRNAs and pulmonary fibroblast mitochondrial function; however, the underlying mechanism is unclear. C57BL/6 mice were intratracheally injected with bleomycin (5 mg/kg) and treated with CCM (25 mg/kg body weight/3 times per week, intraperitoneal injection) for 28 days. Verhoeff-Van Gieson, Picro sirius red, and Masson's trichrome staining were used to examine the expression and distribution of collagen and elastic fibers in the lung tissue. Pulmonary fibrosis was determined using micro-computed tomography and transmission electron microscopy. Human pulmonary fibroblasts were transfected with miR-29a-3p, and RT-qPCR, immunostaining, and western blotting were performed to determine the expression of DNMT3A and extracellular matrix collagen-1 (COL1A1) and fibronectin-1 (FN1) levels. The expression of mitochondrial electron transport chain complex (MRC) and mitochondrial function were detected using western blotting and Seahorse XFp Technology. CCM in increased the expression of miR-29a-3p in the lung tissue and inhibited the DNMT3A to reduce the COL1A1 and FN1 levels leading to pulmonary extracellular matrix remodeling. In addition, CCM inhibited pulmonary fibroblasts MRC and mitochondrial function via the miR-29a-3p/DNMT3A pathway. CCM attenuates pulmonary fibrosis via the miR-29a-3p/DNMT3A axis to regulate extracellular matrix remodeling and mitochondrial function and may provide a new therapeutic intervention for preventing pulmonary fibrosis.

Bleomycin induces senescence and repression of DNA repair via downregulation of Rad51.

BACKGROUND: Bleomycin, a potent antitumor agent, is limited in clinical use due to the potential for fatal pulmonary toxicity. The accelerated DNA damage and senescence in alveolar epithelial cells (AECs) is considered a key factor in the development of lung pathology. Understanding the mechanisms for bleomycin-induced lung injury is crucial for mitigating its adverse effects. METHODS: Human lung epithelial (A549) cells were exposed to bleomycin and subsequently assessed for cellular senescence, DNA damage, and double-strand break (DSB) repair. The impact of Rad51 overexpression on DSB repair and senescence in AECs was evaluated in vitro. Additionally, bleomycin was intratracheally administered in C57BL/6 mice to establish a pulmonary fibrosis model. RESULTS: Bleomycin exposure induced dose- and time-dependent accumulation of senescence hallmarks and DNA lesions in AECs. These effects are probably due to the inhibition of Rad51 expression, consequently suppressing homologous recombination (HR) repair. Mechanistic studies revealed that bleomycin-mediated transcriptional inhibition of Rad51 might primarily result from E2F1 depletion. Furthermore, the genetic supplement of Rad51 substantially mitigated bleomycin-mediated effects on DSB repair and senescence in AECs. Notably, decreased Rad51 expression was also observed in the bleomycin-induced mouse pulmonary fibrosis model. CONCLUSIONS: Our works suggest that the inhibition of Rad51 plays a pivotal role in bleomycin-induced AECs senescence and lung injury, offering potential strategies to alleviate the pulmonary toxicity of bleomycin.

DEC1 is involved in circadian rhythm disruption-exacerbated pulmonary fibrosis.

BACKGROUND: The alveolar epithelial type II cell (AT2) and its senescence play a pivotal role in alveolar damage and pulmonary fibrosis. Cell circadian rhythm is strongly associated with cell senescence. Differentiated embryonic chondrocyte expressed gene 1 (DEC1) is a very important circadian clock gene. However, the role of DEC1 in AT2 senescence and pulmonary fibrosis was still unclear. RESULTS: In this study, a circadian disruption model of light intervention was used. It was found that circadian disruption exacerbated pulmonary fibrosis in mice. To understand the underlying mechanism, DEC1 levels were investigated. Results showed that DEC1 levels increased in lung tissues of IPF patients and in bleomycin-induced mouse fibrotic lungs. In vitro study revealed that bleomycin and TGF-ß1 increased the expressions of DEC1, collagen-I, and fibronectin in AT2 cells. Inhibition of DEC1 mitigated bleomycin-induced fibrotic changes in vitro and in vivo. After that, cell senescence was observed in bleomycin-treated AT2 cells and mouse models, but these were prevented by DEC1 inhibition. At last, p21 was confirmed having circadian rhythm followed DEC1 in normal conditions. But bleomycin disrupted the circadian rhythm and increased DEC1 which promoted p21 expression, increased p21 mediated AT2 senescence and pulmonary fibrosis. CONCLUSIONS: Taken together, circadian clock protein DEC1 mediated pulmonary fibrosis via p21 and cell senescence in alveolar epithelial type II cells.

Research on the potential mechanism of Deapioplatycodin D against pulmonary fibrosis based on bioinformatics and experimental verification.

BACKGROUND: Pulmonary fibrosis (PF) is a group of respiratory diseases that are extremely complex and challenging to treat. Due to its high mortality rate and short survival, it's often referred to as a "tumor-like disease" that poses a serious threat to human health. OBJECTIVE: We aimed validate the potential of Deapioplatycodin D (DPD) to against PF and clarify the underlying mechanism of action of DPD for the treatment of PF based on bioinformatics and experimental verification. This finding provides a basis for the development of safe and effective therapeutic PF drugs based on DPD. METHODS: We used LPS-induced early PF rats as a PF model to test the overall efficacy of DPD in vivo. Then, A variety of bioinformatics methods, such as WGCNA, LASSO algorithm and immune cell infiltration (ICI), were applied to analyze the gene microarray related to PF obtained from Gene Expression Omnibus (GEO) to obtained key targets of PF. Finally, an in vitro PF model was constructed based on BEAS-2B cells while incorporating rat lung tissues to validate the regulatory effects of DPD on critical genes. RESULTS: DPD can effectively alleviate inflammatory and fibrotic markers in rat lungs. WGCNA analysis resulted in a total of six expression modules, with the brown module having the highest correlation with PF. Subsequently, seven genes were acquired by intersecting the genes in the brown module with DEGs. Five key genes were identified as potential biomarkers of PF by LASSO algorithm and validation dataset verification analysis. In the ICI analysis, infiltration of activated B cell, immature B cell and natural killer cells were found to be more crucial in PF. Ultimately, it was observed that DPD could modulate key genes to achieve anti-PF effects. CONCLUSION: In short, these comprehensive analysis methods were employed to identify critical biomarkers closely related to PF, which helps to elucidate the pathogenesis and potential immunotherapy targets of PF. It also provides essential support for the potential of DPD against PF.

Expanding the understanding of telomere biology disorder with reports from two families harboring variants in ZCCHC8 and TERC.

Telomere biology disorder (TBD) can present within a wide spectrum of symptoms ranging from severe congenital malformations to isolated organ dysfunction in adulthood. Diagnosing TBD can be challenging given the substantial variation in symptoms and age of onset across generations. In this report, we present two families, one with a pathogenic variant in ZCCHC8 and another with a novel variant in TERC. In the literature, only one family has previously been reported with a ZCCHC8 variant and TBD symptoms. This family had multiple occurrences of pulmonary fibrosis and one case of bone marrow failure. In this paper, we present a second family with the same ZCCHC8 variant (p.Pro186Leu) and symptoms of TBD including pulmonary fibrosis, hematological disease, and elevated liver enzymes. The suspicion of TBD was confirmed with the measurement of short telomeres in the proband. In another family, we report a novel likely pathogenic variant in TERC. Our comprehensive description encompasses hematological manifestations, as well as pulmonary and hepatic fibrosis. Notably, there are no other reports which associate this variant to disease. The families expand our understanding of the clinical implications and genetic causes of TBD.

The novel molecular mechanism of pulmonary fibrosis: insight into lipid metabolism from reanalysis of single-cell RNA-seq databases.

Pulmonary fibrosis (PF) is a severe pulmonary disease with limited available therapeutic choices. Recent evidence increasingly points to abnormal lipid metabolism as a critical factor in PF pathogenesis. Our latest research identifies the dysregulation of low-density lipoprotein (LDL) is a new risk factor for PF, contributing to alveolar epithelial and endothelial cell damage, and fibroblast activation. In this study, we first integrative summarize the published literature about lipid metabolite changes found in PF, including phospholipids, glycolipids, steroids, fatty acids, triglycerides, and lipoproteins. We then reanalyze two single-cell RNA-sequencing (scRNA-seq) datasets of PF, and the corresponding lipid metabolomic genes responsible for these lipids' biosynthesis, catabolism, transport, and modification processes are uncovered. Intriguingly, we found that macrophage is the most active cell type in lipid metabolism, with almost all lipid metabolic genes being altered in macrophages of PF. In type 2 alveolar epithelial cells, lipid metabolic differentially expressed genes (DEGs) are primarily associated with the cytidine diphosphate diacylglycerol pathway, cholesterol metabolism, and triglyceride synthesis. Endothelial cells are partly responsible for sphingomyelin, phosphatidylcholine, and phosphatidylethanolamines reprogramming as their metabolic genes are dysregulated in PF. Fibroblasts may contribute to abnormal cholesterol, phosphatidylcholine, and phosphatidylethanolamine metabolism in PF. Therefore, the reprogrammed lipid profiles in PF may be attributed to the aberrant expression of lipid metabolic genes in different cell types. Taken together, these insights underscore the potential of targeting lipid metabolism in developing innovative therapeutic strategies, potentially leading to extended overall survival in individuals affected by PF.