Metabolic Profiling Regarding Pathogenesis of Idiopathic Pulmonary Fibrosis

Advances and challenges in kidney fibrosis therapeutics

Chronic kidney disease (CKD) is a major global health burden that affects more than 10% of the adult population. Current treatments, including dialysis and transplantation, are costly and not curative. Kidney fibrosis, defined as an abnormal accumulation of extracellular matrix in the kidney parenchyma, is a common outcome in CKD, regardless of disease aetiology, and is a major cause of loss of kidney function and kidney failure. For this reason, research efforts have focused on identifying mediators of kidney fibrosis to inform the development of effective anti-fibrotic treatments. Given the prominent role of the transforming growth factor-β (TGFβ) family in fibrosis, efforts have focused on inhibiting TGFβ signalling. Despite hopes raised by the efficacy of this approach in preclinical models, translation into clinical practice has not met expectations. Antihypertensive and antidiabetic drugs slow the decline in kidney function and could slow fibrosis but, owing to the lack of technologies for in vivo renal imaging, their anti-fibrotic effect cannot be truly assessed at present. The emergence of new drugs targeting pro-fibrotic signalling, or enabling cell repair and cell metabolic reprogramming, combined with better stratification of people with CKD and the arrival of nanotechnologies for kidney-specific drug delivery, open up new perspectives for the treatment of this major public health challenge.

mTOR signaling regulates multiple metabolic pathways in human lung fibroblasts after TGF-β and in pulmonary fibrosis

Idiopathic pulmonary fibrosis is a fatal disease characterized by the transforming growth factor (TGF-β)-dependent activation of lung fibroblasts, leading to excessive deposition of collagen proteins and progressive replacement of healthy lungs with scar tissue. We and others have shown that TGF-β-mediated activation of the mechanistic target of rapamycin complex 1 (mTORC1) and downstream upregulation of activating transcription factor 4 (ATF4) promotes metabolic reprogramming in lung fibroblasts characterized by upregulation of the de novo synthesis of glycine, the most abundant amino acid found in collagen protein. Whether mTOR and ATF4 regulate other metabolic pathways in lung fibroblasts has not been explored. Here, we used RNA sequencing to determine how both ATF4 and mTOR regulate gene expression in human lung fibroblasts following TGF-β. We found that ATF4 primarily regulates enzymes and transporters involved in amino acid homeostasis as well as aminoacyl-tRNA synthetases. mTOR inhibition resulted not only in the loss of ATF4 target gene expression but also in the reduced expression of glycolytic enzymes and mitochondrial electron transport chain subunits. Analysis of TGF-β-induced changes in cellular metabolite levels confirmed that ATF4 regulates amino acid homeostasis in lung fibroblasts, whereas mTOR also regulates glycolytic and TCA cycle metabolites. We further analyzed publicly available single-cell RNA-seq datasets and found increased expression of ATF4 and mTOR-regulated genes in pathologic fibroblast populations from the lungs of patients with IPF. Our results provide insight into the mechanisms of metabolic reprogramming in lung fibroblasts and highlight novel ATF4 and mTOR-dependent pathways that may be targeted to inhibit fibrotic processes.NEW & NOTEWORTHY Here, we used transcriptomic and metabolomic approaches to develop a more complete understanding of the role that mTOR, and its downstream effector ATF4, play in promoting metabolic reprogramming in lung fibroblasts. We identify novel metabolic pathways that may promote pathologic phenotypes, and we provide evidence from single-cell RNA-seq datasets that similar metabolic reprogramming occurs in patient lungs.

Bleomycin pollution and lung health: The therapeutic potential of peimine in bleomycin-induced pulmonary fibrosis by inhibiting glycolysis

The increasing use of anticancer drugs has led to the emergence of environmental contaminants such as bleomycin (BLM), which poses significant threats to both aquatic ecosystems and human health. Bleomycin, known for its DNA-damaging properties, is extensively used in oncology. Its resistance to biodegradation, along with the limitations of conventional wastewater treatment processes, facilitates environmental accumulation from various sources, highlighting the need for effective management and treatment strategies to mitigate ecological and health risks. This study investigates the link between BLM pollution and pulmonary fibrosis, a progressive lung disease characterized by tissue scarring and loss of function. We demonstrate that BLM induces pulmonary fibrosis in mice and enhances glycolysis and fibroblast activation. Our findings also indicate that peimine, a natural compound derived from Fritillaria, suppresses fibroblast activation and ameliorates pulmonary fibrosis by inhibiting glycolysis through the PI3K/Akt/PFKFB3 signaling pathway. Taken together, this study underscores the environmental and health risks associated with the accumulation of cytostatic drugs like BLM and highlights the therapeutic potential of natural compounds such as peimine. Our results contribute to the development of novel strategies for the prevention and treatment of pulmonary fibrosis and call for better management practices to mitigate the environmental impact of cytostatic drugs.

ANGPTL4 mediated mesothelial-mesenchymal transition in pulmonary fibrosis: a potential therapeutic target

BACKGROUND

Glycolysis plays a major role in progression of idiopathic pulmonary fibrosis (IPF). Here, we aim to explore the predictive signature based on glycolysis-related genes for predicting the prognosis and identified a potential therapeutic target for IPF.

METHODS

Gene expression data of bronchoalveolar lavage (BAL) cells and clinical information were downloaded from the Gene Expression Omnibus database. Bioinformatic analysis was then performed to identify differentially expressed genes (DEGs). Lasso multivariate cox analysis and multivariate Cox regression were used to establish a gene signature. The prediction model was evaluated using the time-dependent receiver operating characteristic (ROC) curve and validated using an external independent dataset. The expression of these key genes in cellular level analyzed from Single Cell Expression Atlas. Cell Counting Kit-8 assay, immunofluorescence, wound healing and plasmid transfection were performed.

RESULTS

A total of 4 gene (ANGPTL4, ME2, TPBG and IER3), which were associated with the prognosis of IPF patients, were selected to establish our signature. The prediction model was an independent prognostic indicator for IPF patients. ANGPTL4 was significantly upregulated in pleural mesothelial cells (PMCs). In vitro assay showed that ANGPTL4 promoted PMCs proliferation and migration. Knockdown of ANGPTL4 can inhibit mesothelial-mesenchymal transition by suppressed glycolysis-associated gene, such as PGM1, GPI, PGK1, LDHA, ALDOA, ENO1 and TPI1.

CONCLUSIONS

Our research established a glycolysis-associated gene signature that holds potential to assist clinicians in the personalized management of IPF. Furthermore, we identified that ANGPTL4 mediates mesothelial-mesenchymal transition, suggesting its viability as a therapeutic target for IPF treatment.

Novel pilot study on plasma metabolites and biomarkers in a rat model of silica-induced lung inflammation and fibrosis

Silica-induced lung damage may be associated with changes in distinct metabolites potentially serving as biomarkers. Due to the lack of metabolomic data from animal models, this pilot study aimed to evaluate changes in markers of inflammation and fibrosis, as well as plasma metabolites in rats at 14 and 28 days after silica instillation. Adult male Wistar rats were administered a single oropharyngeal intratracheal dose of silica suspension or sterile saline in controls. Selected markers of inflammation, oxidative stress, fibrosis, and cell counts in blood and bronchoalveolar lavage fluid have been evaluated. Finally, plasma metabolites were detected using a targeted metabolomics approach with an MxP® Quant 500 kit. Silica instillation induced noticeable inflammatory, oxidative, and fibrotic changes in lung tissue within the first 14 days. During the next two weeks, the shifts in some markers were further accentuated. After exposure to silica, the metabolomic analysis identified significant changes in metabolites associated with lipid metabolism, biogenic amines, amino acid derivatives, carboxylic acids, bile acids, putrescine, glycosylceramides, and acylcarnitines. This pilot study provides initial evidence that significant alterations in plasma metabolite profiles accompany silica-induced lung injury in rats. These findings suggest a possible systemic impact, particularly on lipid metabolism, and indicate the urgent need for a deeper understanding of the metabolic reprogramming associated with silica-induced lung injury to pave the way for the discovery of novel biomarkers.

Role of Arginine and its Metabolism in TGF-β-Induced Activation of Lung Fibroblasts

Arginine is a conditionally essential amino acid with known roles in protein production, nitric oxide synthesis, biosynthesis of proline and polyamines, and regulation of intracellular signaling pathways. Arginine biosynthesis and catabolism have been linked to TGF-β-induced activation of fibroblasts in the context of pulmonary fibrosis; however, a thorough study on the metabolic and signaling roles of arginine in the process of fibroblast activation has not been conducted. Here, we used metabolic dropouts and labeling strategies to determine how activated fibroblasts utilize arginine. We found that arginine limitation leads to activation of GCN2 while inhibiting TGF-β-induced mTORC1 activation and collagen protein production. Extracellular citrulline could rescue the effect of arginine deprivation in an ASS1-dependent manner. Using metabolic tracers of arginine and its precursors, we found little evidence of arginine synthesis or catabolism in lung fibroblasts treated with TGF-β. Extracellular ornithine or glutamine were the primary sources of ornithine and polyamines, not arginine. Our findings suggest that the major role for arginine in lung fibroblasts is for charging of arginyl-tRNAs and for promotion of mTOR signaling.

Highlights

Arginine depletion inhibits TGF-β-induced transcription in human lung fibroblasts (HLFs).Arginine is not significantly catabolized in HLFs either through NOS or ARG dependent pathways.Extracellular glutamine and ornithine are the primary sources of polyamines in lung fibroblasts.The primary role of arginine in lung fibroblasts is for signaling through mTOR and GNC2.

Pathogenesis and Therapy of Hermansky-Pudlak Syndrome (HPS)-Associated Pulmonary Fibrosis

Hermansky-Pudlak syndrome (HPS)-associated pulmonary fibrosis (HPS-PF) is a progressive lung disease that is a major cause of morbidity and mortality in HPS patients. Previous studies have demonstrated that the HPS proteins play an essential role in the biogenesis and function of lysosome-related organelles (LROs) in alveolar epithelial type II (AT2) cells and found that HPS-PF is associated with dysfunction of AT2 cells and abnormal immune reactions. Despite recent advances in research on HPS and the pathology of HPS-PF, the pathological mechanisms underlying HPS-PF remain poorly understood, and no effective treatment has been established. Therefore, it is necessary to refresh the progress in the pathogenesis of HPS-PF to increase our understanding of the pathogenic mechanism of HPS-PF and develop targeted therapeutic strategies. This review summarizes the recent progress in the pathogenesis of HPS-PF provides information about the current treatment strategies for HPS-PF, and hopefully increases our understanding of the pathogenesis of HPS-PF and offers thoughts for new therapeutic interventions.

A pilot metabolomics study across the continuum of interstitial lung disease fibrosis severity

Interstitial lung diseases (ILDs) include a variety of inflammatory and fibrotic pulmonary conditions. This study employs high-resolution metabolomics (HRM) to explore plasma metabolites and pathways across ILD phenotypes, including non-fibrotic ILD, idiopathic pulmonary fibrosis (IPF), and non-IPF fibrotic ILD. The study used 80 plasma samples for HRM, and involved linear trend and group-wise analyses of metabolites altered in ILD phenotypes. We utilized limma one-way ANOVA and mummichog algorithms to identify differences in metabolites and pathways across ILD groups. Then, we focused on metabolites within critical pathways, indicated by high pathway overlap sizes and low p-values, for further analysis. Targeted HRM identified putrescine, hydroxyproline, prolyl-hydroxyproline, aspartate, and glutamate with significant linear increases in more fibrotic ILD phenotypes, suggesting their role in ILD fibrogenesis. Untargeted HRM highlighted pathway alterations in lysine, vitamin D3, tyrosine, and urea cycle metabolism, all associated with pulmonary fibrosis. In addition, methylparaben level had a significantly increasing linear trend and was higher in the IPF than fibrotic and non-ILD groups. This study highlights the importance of specific amino acids, metabolic pathways, and xenobiotics in the progression of pulmonary fibrosis.

Targeting reprogrammed metabolism as a therapeutic approach for respiratory diseases

Metabolic reprogramming underlies the etiology and pathophysiology of respiratory diseases such as asthma, idiopathic pulmonary fibrosis (IPF), and chronic obstructive pulmonary disease (COPD). The dysregulated cellular activities driving airway inflammation and remodelling in these diseases have reportedly been linked to aberrant shifts in energy-producing metabolic pathways: glycolysis and oxidative phosphorylation (OXPHOS). The rewiring of glycolysis and OXPHOS accompanying the therapeutic effects of many clinical compounds and natural products in asthma, IPF, and COPD, supports targeting metabolism as a therapeutic approach for respiratory diseases. Correspondingly, inhibiting glycolysis has largely attested effective against experimental asthma, IPF, and COPD. However, modulating OXPHOS and its supporting catabolic pathways like mitochondrial pyruvate catabolism, fatty acid β-oxidation (FAO), and glutaminolysis for these respiratory diseases remain inconclusive. An emerging repertoire of metabolic enzymes are also interconnected to these canonical metabolic pathways that similarly possess therapeutic potential for respiratory diseases. Taken together, this review highlights the urgent demand for future studies to ascertain the role of OXPHOS in different respiratory diseases, under different stimulatory conditions, and in different cell types. While this review provides strong experimental evidence in support of the inhibition of glycolysis for asthma, IPF, and COPD, further verification by clinical trials is definitely required.

Pulmonary Fibrosis Diagnosis and Disease Progression Detected Via Hair Metabolome Analysis

BACKGROUND

Fibrotic interstitial lung disease is often identified late due to non-specific symptoms, inadequate access to specialist care, and clinical unawareness precluding proper and timely treatment. Biopsy histological analysis is definitive but rarely performed due to its invasiveness. Diagnosis typically relies on high-resolution computed tomography, while disease progression is evaluated via frequent pulmonary function testing. This study tested the hypothesis that pulmonary fibrosis diagnosis and progression could be non-invasively and accurately evaluated from the hair metabolome, with the longer-term goal to minimize patient discomfort.

METHODS

Hair specimens collected from pulmonary fibrosis patients (n = 56) and healthy subjects (n = 14) were processed for metabolite extraction using 2DLC/MS-MS, and data were analyzed via machine learning. Metabolomic data were used to train machine learning classification models tuned via a rigorous combination of cross validation, feature selection, and testing with a hold-out dataset to evaluate classifications of diseased vs. healthy subjects and stable vs. progressed disease.

RESULTS

Prediction of pulmonary fibrosis vs. healthy achieved AUROCTRAIN = 0.888 (0.794-0.982) and AUROCTEST = 0.908, while prediction of stable vs. progressed disease achieved AUROCTRAIN = 0.833 (0.784 - 0.882) and AUROCTEST = 0. 799. Top metabolites for diagnosis included ornithine, 4-(methylnitrosamino)-1-3-pyridyl-N-oxide-1-butanol, Thr-Phe, desthiobiotin, and proline. Top metabolites for progression included azelaic acid, Thr-Phe, Ala-Tyr, indoleacetyl glutamic acid, and cytidine.

CONCLUSION

This study provides novel evidence that pulmonary fibrosis diagnosis and progression may in principle be evaluated from the hair metabolome. Longer term, this approach may facilitate non-invasive and accurate detection and monitoring of fibrotic lung diseases.

BRD4: an effective target for organ fibrosis

Fibrosis is an excessive wound-healing response induced by repeated or chronic external stimuli to tissues, significantly impacting quality of life and primarily contributing to organ failure. Organ fibrosis is reported to cause 45% of all-cause mortality worldwide. Despite extensive efforts to develop new antifibrotic drugs, drug discovery has not kept pace with the clinical demand. Currently, only pirfenidone and nintedanib are approved by the FDA to treat pulmonary fibrotic illness, whereas there are currently no available antifibrotic drugs for hepatic, cardiac or renal fibrosis. The development of fibrosis is closely related to epigenetic alterations. The field of epigenetics primarily studies biological processes, including chromatin modifications, epigenetic readers, DNA transcription and RNA translation. The bromodomain and extra-terminal structural domain (BET) family, a class of epigenetic readers, specifically recognizes acetylated histone lysine residues and promotes the formation of transcriptional complexes. Bromodomain-containing protein 4 (BRD4) is one of the most well-researched proteins in the BET family. BRD4 is implicated in the expression of genes related to inflammation and pro-fibrosis during fibrosis. Inhibition of BRD4 has shown promising anti-fibrotic effects in preclinical studies; however, no BRD4 inhibitor has been approved for clinical use. This review introduces the structure and function of BET proteins, the research progress on BRD4 in organ fibrosis, and the inhibitors of BRD4 utilized in fibrosis. We emphasize the feasibility of targeting BRD4 as an anti-fibrotic strategy and discuss the therapeutic potential and challenges associated with BRD4 inhibitors in treating fibrotic diseases.

Causal relationship between serum metabolites and idiopathic pulmonary fibrosis: Insights from a two-sample Mendelian randomization study

Background

Idiopathic pulmonary fibrosis (IPF) is an irreversible lung disease with unclear pathological mechanisms. In this study, we utilized bidirectional Mendelian randomization (MR) to analyze the relationship between serum metabolites and IPF, and conducted metabolic pathway analysis.

Aim

To determine the causal relationship between serum metabolites and IPF using MR analysis.

Methods

A two-sample MR analysis was conducted to evaluate the causal relationship between 824 serum metabolites and IPF. The inverse variance weighted (IVW) method was used to estimate the causal relationship between exposure and results. Sensitivity analysis was conducted using MR Egger, weighted median, and maximum likelihood to eliminate pleiotropy. Additionally, metabolic pathway analysis was conducted to identify potential metabolic pathways.

Results

We identified 12 serum metabolites (6 risks and 6 protective) associated with IPF from 824 metabolites. Among them, 11 were known and 1 was unknown. 1-Eicosatrienoylglycophorophospholine and 1-myristoylglycophorophospholine were bidirectional MR positive factors, with 1-myristoylglycophorophospholine being a risk factor (1.0013, 1.0097) and 1-eicosatrienoylglycophorine being a protective factor (0.9914, 0.9990). The four lipids (1-linoleoylglycerophoethanolamine*, total cholesterol in large high-density lipoprotein [HDL], cholesterol esters in very large HDL, and phospholipids in very large HDL) and one NA metabolite (degree of unsaturation) were included in the known hazardous metabolites. The known protective metabolites included three types of lipids (carnitine, 1-linoleoylglycerophoethanolamine*, and 1-eicosatrienoylglycerophophophorine), one amino acid (hypoxanthine), and two unknown metabolites (the ratio of omega-6 fatty acids to omega-3 fatty acids, and the ratio of photoshopids to total lipids ratio in chylomicrons and extremely large very low-density lipoprotein [VLDL]). Moreover, sn-Glycerol 3-phosphate and 1-Acyl-sn-glycero-3-phosphocline were found to be involved in the pathogenesis of IPF through metabolic pathways such as Glycerolide metabolism and Glycerophospholipid metabolism.

Conclusion

Our study identified 6 causal risks and 6 protective serum metabolites associated with IPF. Additionally, 2 metabolites were found to be involved in the pathogenesis of IPF through metabolic pathways, providing a new perspective for further understanding the metabolic pathway and the pathogenesis of IPF.

Unraveling the immunometabolism puzzle: Deciphering systemic sclerosis pathogenesis

The article delves into the pathogenesis of systemic sclerosis (SSc) with an emphasis on immunometabolism dysfunctions. SSc is a complex autoimmune connective tissue disorder with skin and organ fibrosis manifestation, vasculopathy, and immune dysregulation. A growing amount of research indicates that immunometabolism plays a significant role in the pathogenesis of autoimmune diseases, including SSc. The review explores the intricate interplay between immune dysfunction and metabolic alterations, focusing on the metabolism of glucose, lipids, amino acids, the TCA (tricarboxylic acid) cycle, and oxidative stress in SSc disease. According to recent research, there are changes in various metabolic pathways that could trigger or perpetuate the SSc disease. Glycolysis and TCA pathways play a pivotal role in SSc pathogenesis through inducing fibrosis. Dysregulated fatty acid β-oxidation (FAO) and consequent lipid metabolism result in dysregulated extracellular matrix (ECM) breakdown and fibrosis induction. The altered metabolism of amino acids can significantly be involved in SSc pathogenesis through various mechanisms. Reactive oxygen species (ROS) production has a crucial role in tissue damage in SSc patients. Indeed, immunometabolism involvement in SSc is highlighted, which offers potential therapeutic avenues. The article underscores the need for comprehensive studies to unravel the multifaceted mechanisms driving SSc pathogenesis and progression.

Targeted proteomic approach for quantification of collagen type I and type III in formalin-fixed paraffin-embedded tissue

Collagen is the most abundant protein in mammals and a major structural component of the extracellular matrix (ECM). Changes to ECM composition occur as a result of numerous physiological and pathophysiological causes, and a common means to evaluate these changes is the collagen 3 (Col3) to collagen 1 (Col1) ratio. Current methods to measure the Col3/1 ratio suffer from a lack of specificity and often under- or over-estimate collagen composition and quantity. This manuscript presents a targeted liquid chromatography tandem mass spectrometry (LC-MS/MS) method for quantification of Col3 and Col1 in FFPE tissues. Using surrogate peptides to generate calibration curves, Col3 and Col1 are readily quantified in FFPE tissue sections with high accuracy and precision. The method is applied to several tissue types from both human and reindeer sources, demonstrating its generalizability. In addition, the targeted LC-MS/MS method permits quantitation of the hydroxyprolinated form of Col3, which has significant implications for understanding not only the quantity of Col3 in tissue, but also understanding of the pathophysiology underlying many causes of ECM changes. This manuscript presents a straightforward, accurate, precise, and generalizable method for quantifying the Col3/1 ratio in a variety of tissue types and organisms.

Disorders of fatty acid metabolism and imbalance in the ratio of monounsaturated fatty acids promote the development of pulmonary fibrosis

OBJECTIVE

Although some studies suggested that metabolic abnormalities may contribute to the development of pulmonary fibrosis, there are no studies that have reported a clear causal relationship between them, and the aim of this study was to explore the causal relationship between plasma metabolites and pulmonary fibrosis using Mendelian randomization (MR) combined with metabolomics analysis.

METHODS

Firstly, we explored the causal relationship between 1400 metabolites and pulmonary fibrosis using MR analysis, and detected plasma metabolites in mice with pulmonary fibrosis using metabolomics technology, thus validating the results of MR analysis. In addition, we again used MR to explore the causal relationship between the results of the differential metabolite KEGG in metabolomics and pulmonary fibrosis.

RESULTS

A total of 52 metabolites were screened for association with pulmonary fibrosis in the MR analysis of 1400 plasma metabolites with pulmonary fibrosis, based on P < 0.05 for the IVW method, with consistent OR directions for all methods. Four of them were validated in the plasma of mice with pulmonary fibrosis, namely carnitine c18:2 levels (negative correlation), Glutamine degradant levels (positive correlation), Propionylcarnitine (c3) levels (negative correlation), carnitine to palmitoylcarnitine (c16) ratio (negative correlation). In addition, KEGG analysis of plasma differential metabolites revealed that the signaling pathway of biosynthetic of unsaturated fatty acids was most affected in mice with pulmonary fibrosis, and MR analysis showed that imbalance in the ratio of monounsaturated fatty acids was significantly associated with pulmonary fibrosis.

CONCLUSIONS

Our study suggests that abnormal fatty acid levels due to reduced levels of carnitine-like metabolites, and an imbalance in the ratio of monounsaturated, promote the development of pulmonary fibrosis. This study reveals the marker metabolites and metabolic pathways affecting the development of pulmonary fibrosis to provide a basis for the development of new drugs for the treatment of pulmonary fibrosis.

Succinate promotes pulmonary fibrosis through GPR91 and predicts death in idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is believed to be associated with a notable disruption of cellular energy metabolism. By detecting the changes of energy metabolites in the serum of patients with pulmonary fibrosis, we aimed to investigate the diagnostic and prognostic value of energy metabolites in IPF, and further elucidated the mechanism of their involvement in pulmonary fibrosis. Through metabolomics research, it was discovered that the TCA cycle intermediates changed dramatically in IPF patients. In another validation cohort of 55 patients with IPF compared to 19 healthy controls, it was found that succinate, an intermediate product of TCA cycle, has diagnostic and prognostic value in IPF. The cut-off levels of serum succinate were 98.36 μM for distinguishing IPF from healthy controls (sensitivity, 83.64%; specificity, 63.16%; likelihood ratio, 2.27, respectively). Moreover, a high serum succinate level was independently associated with higher rates of disease progression (OR 13.087, 95%CI (2.819-60.761)) and mortality (HR 3.418, 95% CI (1.308-8.927)). In addition, accumulation of succinate and increased expression of the succinate receptor GPR91 were found in both IPF patients and BLM mouse models of pulmonary fibrosis. Reducing succinate accumulation in BLM mice alleviated pulmonary fibrosis and 21d mortality, while exogenous administration of succinate can aggravate pulmonary fibrosis in BLM mice. Furthermore, GPR91 deficiency protected against lung fibrosis caused by BLM. In vitro, succinate promoted the activation of lung fibroblasts by activating ERK pathway through GPR91. In summary, succinate is a promising biomarker for diagnosis and prognosis of IPF. The accumulation of succinate may promote fibroblast activation through GPR91 and pulmonary fibrosis.

LPS-induced monocarboxylate transporter-1 inhibition facilitates lactate accumulation triggering epithelial-mesenchymal transformation and pulmonary fibrosis

The epithelial-mesenchymal transformation (EMT) process of alveolar epithelial cells is recognized as involved in the development of pulmonary fibrosis. Recent evidence has shown that lipopolysaccharide (LPS)-induced aerobic glycolysis of lung tissue and elevated lactate concentration are associated with the pathogenesis of sepsis-associated pulmonary fibrosis. However, it is uncertain whether LPS promotes the development of sepsis-associated pulmonary fibrosis by promoting lactate accumulation in lung tissue, thereby initiating EMT process. We hypothesized that monocarboxylate transporter-1 (MCT1), as the main protein for lactate transport, may be crucial in the pathogenic process of sepsis-associated pulmonary fibrosis. We found that high concentrations of lactate induced EMT while moderate concentrations did not. Besides, we demonstrated that MCT1 inhibition enhanced EMT process in MLE-12 cells, while MCT1 upregulation could reverse lactate-induced EMT. LPS could promote EMT in MLE-12 cells through MCT1 inhibition and lactate accumulation, while this could be alleviated by upregulating the expression of MCT1. In addition, the overexpression of MCT1 prevented LPS-induced EMT and pulmonary fibrosis in vivo. Altogether, this study revealed that LPS could inhibit the expression of MCT1 in mouse alveolar epithelial cells and cause lactate transport disorder, which leads to lactate accumulation, and ultimately promotes the process of EMT and lung fibrosis.

The aging lung: microenvironment, mechanisms, and diseases

With the development of global social economy and the deepening of the aging population, diseases related to aging have received increasing attention. The pathogenesis of many respiratory diseases remains unclear, and lung aging is an independent risk factor for respiratory diseases. The aging mechanism of the lung may be involved in the occurrence and development of respiratory diseases. Aging-induced immune, oxidative stress, inflammation, and telomere changes can directly induce and promote the occurrence and development of lung aging. Meanwhile, the occurrence of lung aging also further aggravates the immune stress and inflammatory response of respiratory diseases; the two mutually affect each other and promote the development of respiratory diseases. Explaining the mechanism and treatment direction of these respiratory diseases from the perspective of lung aging will be a new idea and research field. This review summarizes the changes in pulmonary microenvironment, metabolic mechanisms, and the progression of respiratory diseases associated with aging.

The causal relationship between genetically predicted blood metabolites and idiopathic pulmonary fibrosis: A bidirectional two-sample Mendelian randomization study

BACKGROUND

Numerous metabolomic studies have confirmed the pivotal role of metabolic abnormalities in the development of idiopathic pulmonary fibrosis (IPF). Nevertheless, there is a lack of evidence on the causal relationship between circulating metabolites and the risk of IPF.

METHODS

The potential causality between 486 blood metabolites and IPF was determined through a bidirectional two-sample Mendelian randomization (TSMR) analysis. A genome-wide association study (GWAS) involving 7,824 participants was performed to analyze metabolite data, and a GWAS meta-analysis involving 6,257 IPF cases and 947,616 control European subjects was conducted to analyze IPF data. The TSMR analysis was performed primarily with the inverse variance weighted model, supplemented by weighted mode, MR-Egger regression, and weighted median estimators. A battery of sensitivity analyses was performed, including horizontal pleiotropy assessment, heterogeneity test, Steiger test, and leave-one-out analysis. Furthermore, replication analysis and meta-analysis were conducted with another GWAS dataset of IPF containing 4,125 IPF cases and 20,464 control subjects. Mediation analyses were used to identify the mediating role of confounders in the effect of metabolites on IPF.

RESULTS

There were four metabolites associated with the elevated risk of IPF, namely glucose (odds ratio [OR] = 2.49, 95% confidence interval [95%CI] = 1.13-5.49, P = 0.024), urea (OR = 6.24, 95% CI = 1.77-22.02, P = 0.004), guanosine (OR = 1.57, 95%CI = 1.07-2.30, P = 0.021), and ADpSGEGDFXAEGGGVR (OR = 1.70, 95%CI = 1.00-2.88, P = 0.0496). Of note, the effect of guanosine on IPF was found to be mediated by gastroesophageal reflux disease. Reverse Mendelian randomization analysis displayed that IPF might slightly elevate guanosine levels in the blood.

CONCLUSION

Conclusively, hyperglycemia may confer a promoting effect on IPF, highlighting that attention should be paid to the relationship between diabetes and IPF, not solely to the diagnosis of diabetes. Additionally, urea, guanosine, and ADpSGEGDFXAEGGGVR also facilitate the development of IPF. This study may provide a reference for analyzing the potential mechanism of IPF and carry implications for the prevention and treatment of IPF.

Role of lung ornithine aminotransferase in idiopathic pulmonary fibrosis: regulation of mitochondrial ROS generation and TGF-β1 activity

Idiopathic pulmonary fibrosis (IPF) is characterized by aberrant lung remodeling and the excessive accumulation of extracellular matrix (ECM) proteins. In a previous study, we found that the levels of ornithine aminotransferase (OAT), a principal enzyme in the proline metabolism pathway, were increased in the lungs of patients with IPF. However, the precise role played by OAT in the pathogenesis of IPF is not yet clear. The mechanism by which OAT affects fibrogenesis was assessed in vitro using OAT-overexpressing and OAT-knockdown lung fibroblasts. The therapeutic effects of OAT inhibition were assessed in the lungs of bleomycin-treated mice. OAT expression was increased in fibrotic areas, principally in interstitial fibroblasts, of lungs affected by IPF. OAT levels in the bronchoalveolar lavage fluid of IPF patients were inversely correlated with lung function. The survival rate was significantly lower in the group with an OAT level >75.659 ng/mL than in the group with an OAT level ≤75.659 ng/mL (HR, 29.53; p = 0.0008). OAT overexpression and knockdown increased and decreased ECM component production by lung fibroblasts, respectively. OAT knockdown also inhibited transforming growth factor-β1 (TGF)-β1 activity and TGF-β1 pathway signaling. OAT overexpression increased the generation of mitochondrial reactive oxygen species (ROS) by activating proline dehydrogenase. The OAT inhibitor L-canaline significantly attenuated bleomycin-induced lung injury and fibrosis. In conclusion, increased OAT levels in lungs affected by IPF contribute to the progression of fibrosis by promoting excessive mitochondrial ROS production, which in turn activates TGF-β1 signaling. OAT may be a useful target for treating patients with fibrotic lung diseases, including IPF.

Lipid mediators of inhalation exposure-induced pulmonary toxicity and inflammation

Many inhalation exposures induce pulmonary inflammation contributing to disease progression. Inflammatory processes are actively regulated via mediators including bioactive lipids. Bioactive lipids are potent signaling molecules involved in both pro-inflammatory and resolution processes through receptor interactions. The formation and clearance of lipid signaling mediators are controlled by multiple metabolic enzymes. An imbalance of these lipids can result in exacerbated and sustained inflammatory processes which may result in pulmonary damage and disease. Dysregulation of pulmonary bioactive lipids contribute to inflammation and pulmonary toxicity following exposures. For example, inhalation of cigarette smoke induces activation of pro-inflammatory bioactive lipids such as sphingolipids, and ceramides contributing to chronic obstructive pulmonary disease. Additionally, exposure to silver nanoparticles causes dysregulation of inflammatory resolution lipids. As inflammation is a common consequence resulting from inhaled exposures and a component of numerous diseases it represents a broadly applicable target for therapeutic intervention. With new appreciation for bioactive lipids, technological advances to reliably identify and quantify lipids have occurred. In this review, we will summarize, integrate, and discuss findings from recent studies investigating the impact of inhaled exposures on pro-inflammatory and resolution lipids within the lung and their contribution to disease. Throughout the review current knowledge gaps in our understanding of bioactive lipids and their contribution to pulmonary effects of inhaled exposures will be presented. New methods being employed to detect and quantify disruption of pulmonary lipid levels following inhalation exposures will be highlighted. Lastly, we will describe how lipid dysregulation could potentially be addressed by therapeutic strategies to address inflammation.

ACSS3 regulates the metabolic homeostasis of epithelial cells and alleviates pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a progressive and fatal interstitial lung disease of unknown etiology. The emerging evidence demonstrates that metabolic homeostatic imbalance caused by repetitive injuries of the alveolar epithelium is the potential pathogenesis of IPF. Proteomic analysis identified that Acetyl-CoA synthetase short chain family member 3 (ACSS3) expression was decreased in IPF patients and mice with bleomycin-induced fibrosis. ACSS3 participated in lipid and carbohydrate metabolism. Increased expression of ACSS3 downregulated carnitine palmitoyltransferase 1A (CPT-1A) and resulted in the accumulation of lipid droplets, while enhanced glycolysis which led to an increase in extracellular lactic acid levels in A549 cells. ACSS3 increases the production of succinyl-CoA through propionic acid metabolism, and decreases the generation of acetyl-CoA and ATP in alveolar epithelial cells. Overexpression of Acss3 inhibited the excessive deposition of ECM and attenuated the ground-glass opacity which determined by micro-CT in vivo. In a nutshell, our findings demonstrate that ACSS3 decreased the fatty acid oxidation through CPT1A deficiency and enhanced anaerobic glycolysis, this metabolic reprogramming deactivate the alveolar epithelial cells by lessen mitochondrial fission and fusion, increase of ROS production, suppression of mitophagy, promotion of apoptosis, suggesting that ACSS3 might be potential therapeutic target in pulmonary fibrosis.

Circulating metabolic profile in idiopathic pulmonary fibrosis: data from the IPF-PRO Registry

BACKGROUND

The circulating metabolome, reflecting underlying cellular processes and disease biology, has not been fully characterized in patients with idiopathic pulmonary fibrosis (IPF). We evaluated whether circulating levels of metabolites correlate with the presence of IPF, with the severity of IPF, or with the risk of clinically relevant outcomes among patients with IPF.

METHODS

We analyzed enrollment plasma samples from 300 patients with IPF in the IPF-PRO Registry and 100 individuals without known lung disease using a set of targeted metabolomics and clinical analyte modules. Linear regression was used to compare metabolite and clinical analyte levels between patients with IPF and controls and to determine associations between metabolite levels and measures of disease severity in patients with IPF. Unadjusted and adjusted univariable Cox regression models were used to evaluate associations between circulating metabolites and the risk of mortality or disease progression among patients with IPF.

RESULTS

Levels of 64 metabolites and 5 clinical analytes were significantly different between patients with IPF and controls. Among analytes with greatest differences were non-esterified fatty acids, multiple long-chain acylcarnitines, and select ceramides, levels of which were higher among patients with IPF versus controls. Levels of the branched-chain amino acids valine and leucine/isoleucine were inversely correlated with measures of disease severity. After adjusting for clinical factors known to influence outcomes, higher levels of the acylcarnitine C:16-OH/C:14-DC were associated with all-cause mortality, lower levels of the acylcarnitine C16:1-OH/C14:1DC were associated with all-cause mortality, respiratory death, and respiratory death or lung transplant, and higher levels of the sphingomyelin d43:2 were associated with the risk of respiratory death or lung transplantation.

CONCLUSIONS

IPF has a distinct circulating metabolic profile characterized by increased levels of non-esterified fatty acids, long-chain acylcarnitines, and ceramides, which may suggest a more catabolic environment that enhances lipid mobilization and metabolism. We identified select metabolites that were highly correlated with measures of disease severity or the risk of disease progression and that may be developed further as biomarkers.

TRIAL REGISTRATION

ClinicalTrials.gov; No: NCT01915511; URL: www.

CLINICALTRIALS

gov .

Multi-omics integration reveals a nonlinear signature that precedes progression of lung fibrosis

Objectives

Idiopathic pulmonary fibrosis (IPF) is a devastating progressive interstitial lung disease with poor outcomes. While decades of research have shed light on pathophysiological mechanisms associated with the disease, our understanding of the early molecular events driving IPF and its progression is limited. With this study, we aimed to model the leading edge of fibrosis using a data-driven approach.

Methods

Multiple omics modalities (transcriptomics, metabolomics and lipidomics) of healthy and IPF lung explants representing different stages of fibrosis were combined using an unbiased approach. Multi-Omics Factor Analysis of datasets revealed latent factors specifically linked with established fibrotic disease (Factor1) and disease progression (Factor2).

Results

Features characterising Factor1 comprised well-established hallmarks of fibrotic disease such as defects in surfactant, epithelial-mesenchymal transition, extracellular matrix deposition, mitochondrial dysfunction and purine metabolism. Comparatively, Factor2 identified a signature revealing a nonlinear trajectory towards disease progression. Molecular features characterising Factor2 included genes related to transcriptional regulation of cell differentiation, ciliogenesis and a subset of lipids from the endocannabinoid class. Machine learning models, trained upon the top transcriptomics features of each factor, accurately predicted disease status and progression when tested on two independent datasets.

Conclusion

This multi-omics integrative approach has revealed a unique signature which may represent the inflection point in disease progression, representing a promising avenue for the identification of therapeutic targets aimed at addressing the progressive nature of the disease.

Glycolysis Reprogramming in Idiopathic Pulmonary Fibrosis: Unveiling the Mystery of Lactate in the Lung

Idiopathic pulmonary fibrosis (IPF) is a chronic and progressive lung disease characterized by excessive deposition of fibrotic connective tissue in the lungs. Emerging evidence suggests that metabolic alterations, particularly glycolysis reprogramming, play a crucial role in the pathogenesis of IPF. Lactate, once considered a metabolic waste product, is now recognized as a signaling molecule involved in various cellular processes. In the context of IPF, lactate has been shown to promote fibroblast activation, myofibroblast differentiation, and extracellular matrix remodeling. Furthermore, lactate can modulate immune responses and contribute to the pro-inflammatory microenvironment observed in IPF. In addition, lactate has been implicated in the crosstalk between different cell types involved in IPF; it can influence cell-cell communication, cytokine production, and the activation of profibrotic signaling pathways. This review aims to summarize the current research progress on the role of glycolytic reprogramming and lactate in IPF and its potential implications to clarify the role of lactate in IPF and to provide a reference and direction for future research. In conclusion, elucidating the intricate interplay between lactate metabolism and fibrotic processes may lead to the development of innovative therapeutic strategies for IPF.

Capmatinib‑associated interstitial lung disease in a patient with lung adenocarcinoma harboring a skipping mutation of mesenchymal‑epithelial transition exon 14: A case report

Capmatinib is a medication used to treat patients with non-small cell lung cancer (NSCLC) who have a specific genetic mutation known as a mesenchymal-epithelial transition exon 14 skipping mutation. Previous clinical trials have reported that capmatinib treatment has a high objective response rate in patients with this genetic mutation. However, there have also been rare reports of patients developing interstitial lung disease (ILD) following capmatinib treatment, which can be life-threatening. The present case study reports the treatment of a patient who developed ILD after 6 weeks of capmatinib treatment for NSCLC, which was resolved following application of corticosteroids. The present case demonstrated that early recognition of the onset of ILD and discontinuation of capmatinib treatment, along with the prompt initiation of corticosteroid administration, can lead to complete resolution of ILD.

Effect of 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol and benzo[a]pyrene exposure on the development of metabolic syndrome in mice

AIM

The prevalence of metabolic syndrome (MetS), a cluster of serious medical conditions that raise the risk of lung cancer, has increased worldwide. Tobacco smoking (TS) potentially increases the risk of developing MetS. Despite the potential association of MetS with lung cancer, preclinical models that mimic human diseases, including TS-induced MetS, are limited. Here we evaluated the impact of exposure to tobacco smoke condensate (TSC) and two representative tobacco carcinogens, 4-(methylnitrosamino)-1-(3-pyridyl)-1-butanol (NNK) and benzo[a]pyrene (BaP), on MetS development in mice.

MATERIALS AND METHODS

FVB/N or C57BL/6 mice were exposed to vehicle, TSC, or NNK and BaP (NB) twice weekly for 5 months. The serum levels of total cholesterol (TCHO), triglycerides, high-density lipoprotein (HDL), blood glucose, and metabolites, along with glucose tolerance and body weight, were measured.

KEY FINDINGS

Compared with those of vehicle-treated mice, mice with TSC or NB exposure displayed major phenotypes associated with MetS, including increased serum levels of TCHO, triglycerides, and fasting and basal blood glucose and decreased glucose tolerance, and serum levels of HDL. These MetS-associated changes were found in both FVB/N and C57BL/6 mice that were susceptible or resistant to carcinogen-induced tumorigenesis, respectively, indicating that tumor formation is not involved in the TSC- or NB-mediated MetS. Moreover, oleic acid and palmitoleic acid, which are known to be associated with MetS, were significantly upregulated in the serum of TSC- or NB-treated mice compared with those in vehicle-treated mice.

SIGNIFICANCE

Both TSC and NB caused detrimental health problems, leading to the development of MetS in experimental mice.

Dynamic atlas of immune cells reveals multiple functional features of macrophages associated with progression of pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease with a high mortality rate and unclarified aetiology. Immune response is elaborately regulated during the progression of IPF, but immune cells subsets are complicated which has not been detailed described during IPF progression. Therefore, in the current study, we sought to investigate the role of immune regulation by elaborately characterize the heterogeneous of immune cells during the progression of IPF. To this end, we performed single-cell profiling of lung immune cells isolated from four stages of bleomycin-induced pulmonary fibrosis-a classical mouse model that mimics human IPF. The results revealed distinct components of immune cells in different phases of pulmonary fibrosis and close communication between macrophages and other immune cells along with pulmonary fibrosis progression. Enriched signals of SPP1, CCL5 and CXCL2 were found between macrophages and other immune cells. The more detailed definition of the subpopulations of macrophages defined alveolar macrophages (AMs) and monocyte-derived macrophages (mo-Macs)-the two major types of primary lung macrophages-exhibited the highest heterogeneity and dynamic changes in expression of profibrotic genes during disease progression. Our analysis suggested that Gpnmb and Trem2 were both upregulated in macrophages and may play important roles in pulmonary fibrosis progression. Additionally, the metabolic status of AMs and mo-Macs varied with disease progression. In line with the published data on human IPF, macrophages in the mouse model shared some features regarding gene expression and metabolic status with that of macrophages in IPF patients. Our study provides new insights into the pathological features of profibrotic macrophages in the lung that will facilitate the identification of new targets for disease intervention and treatment of IPF.

Mitochondrial Dysfunction in Lung Resident Mesenchymal Stem Cells from Idiopathic Pulmonary Fibrosis Patients

Idiopathic pulmonary fibrosis (IPF) is characterized by an aberrant repair response with uncontrolled turnover of extracellular matrix involving mesenchymal cell phenotypes, where lung resident mesenchymal stem cells (LRMSC) have been supposed to have an important role. However, the contribution of LRMSC in lung fibrosis is not fully understood, and the role of LRMSC in IPF remains to be elucidated. Here, we performed transcriptomic and functional analyses on LRMSC isolated from IPF and control patients (CON). Both over-representation and gene set enrichment analyses indicated that oxidative phosphorylation is the major dysregulated pathway in IPF LRMSC. The most relevant differences in biological processes included complement activation, mesenchyme development, and aerobic electron transport chain. Compared to CON LRMSC, IPF cells displayed impaired mitochondrial respiration, lower expression of genes involved in mitochondrial dynamics, and dysmorphic mitochondria. These changes were linked to an impaired autophagic response and a lower mRNA expression of pro-apoptotic genes. In addition, IPF TGFβ-exposed LRMSC presented different expression profiles of mitochondrial-related genes compared to CON TGFβ-treated cells, suggesting that TGFβ reinforces mitochondrial dysfunction. In conclusion, these results suggest that mitochondrial dysfunction is a major event in LRMSC and that their occurrence might limit LRMSC function, thereby contributing to IPF development.

Integrative analyses for the identification of idiopathic pulmonary fibrosis-associated genes and shared loci with other diseases

BACKGROUND

Although genome-wide association studies (GWAS) have identified many genomic regions associated with idiopathic pulmonary fibrosis (IPF), the causal genes and functions remain largely unknown. Many single-cell expression data have become available for IPF, and there is increasing evidence suggesting a shared genetic basis between IPF and other diseases.

METHODS

We conducted integrative analyses to improve the power of GWAS. First, we calculated global and local genetic correlations to identify IPF genetically associated traits and local regions. Then, we prioritised candidate genes contributing to local genetic correlation. Second, we performed transcriptome-wide association analysis (TWAS) of 44 tissues to identify candidate genes whose genetically predicted expression level is associated with IPF. To replicate our findings and investigate the regulatory role of the transcription factors (TF) in identified candidate genes, we first conducted the heritability enrichment analysis in TF binding sites. Then, we examined the enrichment of the TF target genes in cell-type-specific differentially expressed genes (DEGs) identified from single-cell expression data of IPF and healthy lung samples.

FINDINGS

We identified 12 candidate genes across 13 genomic regions using local genetic correlation, including the POT1 locus (p value=0.00041), which contained variants with protective effects on lung cancer but increasing IPF risk. We identified another 13 novel genes using TWAS. Two TFs, MAFK and SMAD2, showed significant enrichment in both partitioned heritability and cell-type-specific DEGs.

INTERPRETATION

Our integrative analysis identified new genes for IPF susceptibility and expanded the understanding of the complex genetic architecture and disease mechanism of IPF.

Dysregulation of metabolic pathways in pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic progressive disorder of unknown origin and the most common interstitial lung disease. It progresses with the recruitment of fibroblasts and myofibroblasts that contribute to the accumulation of extracellular matrix (ECM) proteins, leading to the loss of compliance and alveolar integrity, compromising the gas exchange capacity of the lung. Moreover, while there are therapeutics available, they do not offer a cure. Thus, there is a pressing need to identify better therapeutic targets. With the advent of transcriptomics, proteomics, and metabolomics, the cellular mechanisms underlying disease progression are better understood. Metabolic homeostasis is one such factor and its dysregulation has been shown to impact the outcome of IPF. Several metabolic pathways involved in the metabolism of lipids, protein and carbohydrates have been implicated in IPF. While metabolites are crucial for the generation of energy, it is now appreciated that metabolites have several non-metabolic roles in regulating cellular processes such as proliferation, signaling, and death among several other functions. Through this review, we succinctly elucidate the role of several metabolic pathways in IPF. Moreover, we also discuss potential therapeutics which target metabolism or metabolic pathways.

The identification of metabolism-related subtypes and potential treatments for idiopathic pulmonary fibrosis

Background: Idiopathic pulmonary fibrosis (IPF) is caused by aberrant repair because of alveolar epithelial injury and can only be effectively treated with several compounds. Several metabolism-related biomolecular processes were found to be involved in IPF. We aimed to identify IPF subtypes based on metabolism-related pathways and explore potential drugs for each subtype. Methods: Gene profiles and clinical information were obtained from the Gene Expression Omnibus (GEO) database (GSE70867 and GSE93606). The enrichment scores for 41 metabolism-related pathways, immune cells, and immune pathways were calculated using the Gene Set Variation Analysis (GSVA) package. The ConsensusClusterPlus package was used to cluster samples. Novel modules and hub genes were identified using weighted correlation network analysis (WGCNA). Receiver operating characteristic (ROC) and calibration curves were plotted, and decision curve analysis (DCA) were performed to evaluate the model in the training and validation cohorts. A connectivity map was used as a drug probe. Results: Two subtypes with significant differences in prognosis were identified based on the metabolism-related pathways. Subtype C1 had a poor prognosis, low metabolic levels, and a unique immune signature. CDS2, LCLAT1, GPD1L, AGPAT1, ALDH3A1, LAP3, ADH5, AHCYL2, and MDH1 were used to distinguish between the two subtypes. Finally, subtype-specific drugs, which can potentially treat IPF, were identified. Conclusion: The aberrant activation of metabolism-related pathways contributes to differential prognoses in patients with IPF. Collectively, our findings provide novel mechanistic insights into subtyping IPF based on the metabolism-related pathway and potential treatments, which would help clinicians provide subtype-specific individualized therapeutic management to patients.

Inositol possesses antifibrotic activity and mitigates pulmonary fibrosis

BACKGROUND

Myo-inositol (or inositol) and its derivatives not only function as important metabolites for multiple cellular processes but also act as co-factors and second messengers in signaling pathways. Although inositol supplementation has been widely studied in various clinical trials, little is known about its effect on idiopathic pulmonary fibrosis (IPF). Recent studies have demonstrated that IPF lung fibroblasts display arginine dependency due to loss of argininosuccinate synthase 1 (ASS1). However, the metabolic mechanisms underlying ASS1 deficiency and its functional consequence in fibrogenic processes are yet to be elucidated.

METHODS

Metabolites extracted from primary lung fibroblasts with different ASS1 status were subjected to untargeted metabolomics analysis. An association of ASS1 deficiency with inositol and its signaling in lung fibroblasts was assessed using molecular biology assays. The therapeutic potential of inositol supplementation in fibroblast phenotypes and lung fibrosis was evaluated in cell-based studies and a bleomycin animal model, respectively.

RESULTS

Our metabolomics studies showed that ASS1-deficient lung fibroblasts derived from IPF patients had significantly altered inositol phosphate metabolism. We observed that decreased inositol-4-monophosphate abundance and increased inositol abundance were associated with ASS1 expression in fibroblasts. Furthermore, genetic knockdown of ASS1 expression in primary normal lung fibroblasts led to the activation of inositol-mediated signalosomes, including EGFR and PKC signaling. Treatment with inositol significantly downregulated ASS1 deficiency-mediated signaling pathways and reduced cell invasiveness in IPF lung fibroblasts. Notably, inositol supplementation also mitigated bleomycin-induced fibrotic lesions and collagen deposition in mice.

CONCLUSION

These findings taken together demonstrate a novel function of inositol in fibrometabolism and pulmonary fibrosis. Our study provides new evidence for the antifibrotic activity of this metabolite and suggests that inositol supplementation may be a promising therapeutic strategy for IPF.

Qimai Feiluoping decoction inhibits mitochondrial complex I-mediated oxidative stress to ameliorate bleomycin-induced pulmonary fibrosis

BACKGROUND

Qimai Feiluoping decoction (QM), a Traditional Chinese Medicine formula, has been included in rehabilitation program for functional disorders of discharged COVID-19 patients. QM has been proved to effectively improve the clinical symptoms and imaging signs of PF in COVID-19 convalescent patients.

PURPOSE

This study to explore the pharmacological effect of QM against PF from the perspectives of imaging, pathological staining, and molecular mechanisms, and identify possible active components.

METHODS

Micro-CT imaging and immunohistochemical staining were investigated to verify the therapeutic effect of QM in the bleomycin (BLM)-induced PF mouse model. The 4D-label-free proteomics analysis of lung tissues was then conducted to explore the novel mechanisms of QM against PF, which were further validated by a series of experiments. The possible components of QM in plasma and lung tissues were identified with UHPLC/IM-QTOF-MS analysis.

RESULTS

The results from micro-CT imaging and pathological staining revealed that QM treatment can inhibit BLM-induced lung injury, extracellular matrix accumulation and TGF-β expression in the mouse model with PF. The 4D-label-free proteomics analysis demonstrated that the partial subunit proteins of mitochondrial complex I and complex II might be potential targets of QM against PF. Furthermore, QM treatment can inhibit BLM-induced mitochondrial ROS content to promote ATP production and decrease oxidative stress injury in the mouse and cell models of PF, which was mediated by the inhibition of mitochondrial complex I. Finally, a total of 13 protype compounds and 15 metabolites from QM in plasma and lung tissues were identified by UHPLC/IM-QTOF-MS, and liquiritin and isoliquiritigenin from Glycyrrhizae radix et rhizoma could be possible active compounds against PF.

CONCLUSION

It concludes that QM treatment could treat PF by inhibiting mitochondrial complex I-mediated mitochondrial oxidated stress injury, which could offer new insights into the pharmacological mechanisms of QM in the clinical application of PF patients.

Processing of carbon-reinforced construction materials releases PM2.5 inducing inflammation and (secondary) genotoxicity in human lung epithelial cells and fibroblasts

Building demolition following domestic fires or abrasive processing after thermal recycling can release particles harmful for the environment and human health. To mimic such situations, particles release during dry-cutting of construction materials was investigated. A reinforcement material consisting of carbon rods (CR), carbon concrete composite (C³) and thermally treated C³ (ttC³) were physicochemically and toxicologically analyzed in monocultured lung epithelial cells, and co-cultured lung epithelial cells and fibroblasts at the air-liquid interface. C³ particles reduced their diameter to WHO fibre dimensions during thermal treatment. Caused by physical properties or by polycyclic aromatic hydrocarbons and bisphenol A found in the materials, especially the released particles of CR and ttC³ induced an acute inflammatory response and (secondary) DNA damage. Transcriptome analysis indicated that CR and ttC³ particles carried out their toxicity via different mechanisms. While ttC³ affected pro-fibrotic pathways, CR was mostly involved in DNA damage response and in pro-oncogenic signaling.

Identification and validation of metabolism-related hub genes in idiopathic pulmonary fibrosis

Background: Idiopathic pulmonary fibrosis (IPF) is a fatal and irreversible interstitial lung disease. The specific mechanisms involved in the pathogenesis of IPF are not fully understood, while metabolic dysregulation has recently been demonstrated to contribute to IPF. This study aims to identify key metabolism-related genes involved in the progression of IPF, providing new insights into the pathogenesis of IPF. Methods: We downloaded four datasets (GSE32537, GSE110147, GSE150910, and GSE92592) from the Gene Expression Omnibus (GEO) database and identified differentially expressed metabolism-related genes (DEMRGs) in lung tissues of IPF by comprehensive analysis. Then, we performed GO, KEGG, and Reactome enrichment analyses of the DEMRGs. Subsequently, key DEMRGs were identified by machine-learning algorithms. Next, miRNAs regulating these key DEMRGs were predicted by integrating the GSE32538 (IPF miRNA dataset) and the miRWalk database. The Cytoscape software was used to visualize miRNA-mRNA regulatory networks. In addition, the relative levels of immune cells were assessed by the CIBERSORT algorithm, and the correlation of key DEMRGs with immune cells was calculated. Finally, the mRNA expression of the key DEMRGs was validated in two external independent datasets and an in vivo experiment. Results: A total of 101 DEMRGs (51 upregulated and 50 downregulated) were identified. Six key DEMRGs (ENPP3, ENTPD1, GPX3, PDE7B, PNMT, and POLR3H) were further identified using two machine-learning algorithms (LASSO and SVM-RFE). In the lung tissue of IPF patients, the expression levels of ENPP3, ENTPD1, and PDE7B were upregulated, and the expression levels of GPX3, PNMT, and POLR3H were downregulated. In addition, the miRNA-mRNA regulatory network of key DEMRGs was constructed. Then, the expression levels of key DEMRGs were validated in two independent external datasets (GSE53845 and GSE213001). Finally, we verified the key DEMRGs in the lung tissue of bleomycin-induced pulmonary fibrosis mice by qRT-PCR. Conclusion: Our study identified key metabolism-related genes that are differentially expressed in the lung tissue of IPF patients. Our study emphasizes the critical role of metabolic dysregulation in IPF, offers potential therapeutic targets, and provides new insights for future studies.

Metabolic landscape dysregulation in bronchoalveolar lavage fluid of checkpoint inhibitor pneumonitis

BACKGROUND

Checkpoint inhibitor pneumonitis (CIP) is a potentially fatal adverse event resulting from immunotherapy in patients with malignant tumors. However, the pathogenesis of CIP remains poorly understood.

METHODS

We collected bronchoalveolar lavage fluid (BALF) from cohorts of patients with CIP, new-onset lung cancer (LC), and idiopathic pulmonary fibrosis (IPF). Non-targeted metabolomics analysis was conducted to analyze metabolic signatures. Flow cytometry was used to evaluate immune cell subsets.

RESULTS

Lymphocytes were predominant in the BALF of patients with CIP. A total of 903 metabolites were identified, among which lipid compounds were the most abundant. In a comparison between patients with CIP and LC, enrichment analysis of the altered metabolites showed suppressed amino sugar metabolism, and spermidine and spermine biosynthesis in the CIP group. Metabolism of alpha linolenic acid, linoleic acid, and their fatty acid derivatives was enriched in the CIP group relative to the IPF group. The twelve metabolites found to be enriched in the CIP group were positively correlated with the proportion of CD8⁺ T cells. One cluster of BALF metabolites, 57.14% of which were lipid molecules, was inversely correlated with the proportion of natural killer cells.

CONCLUSIONS

In this study, the metabolomic landscape of BALF in patients with CIP was determined. We elucidated suppressed tumor metabolic signatures, enhanced pulmonary inflammatory signaling, and the characteristics of responsible immune cells, which helps to understand the pathogenesis of CIP.

Mechanical stress regulates the mechanotransduction and metabolism of cardiac fibroblasts in fibrotic cardiac diseases

Fibrotic cardiac diseases are characterized by myocardial fibrosis that results in maladaptive cardiac remodeling. Cardiac fibroblasts (CFs) are the main cell type responsible for fibrosis. In response to stress or injury, intrinsic CFs develop into myofibroblasts and produce excess extracellular matrix (ECM) proteins. Myofibroblasts are mechanosensitive cells that can detect changes in tissue stiffness and respond accordingly. Previous studies have revealed that some mechanical stimuli control fibroblast behaviors, including ECM formation, cell migration, and other phenotypic traits. Further, metabolic alteration is reported to regulate fibrotic signaling cascades, such as the transforming growth factor-β pathway and ECM deposition. However, the relationship between metabolic changes and mechanical stress during fibroblast-to-myofibroblast transition remains unclear. This review aims to elaborate on the crosstalk between mechanical stress and metabolic changes during the pathological transition of cardiac fibroblasts.

Alamandine/MrgD axis prevents TGF-β1-mediated fibroblast activation via regulation of aerobic glycolysis and mitophagy

BACKGROUND

Idiopathic pulmonary fibrosis is a chronic progressive, lethal disease in which ectopic lung fibroblast (LF) activation plays a vital part. We have previously shown that alamandine (ALA) exerts anti-fibrosis effects via the MAS-related G-protein coupled receptor D (MrgD). Here, we further investigate how it moderates transforming growth factor β1 (TGF-β1)-induced LF activation by regulating glucose metabolism and mitochondria autophagy (mitophagy).

METHODS

In vitro, we examined glycolysis-related protein hexokinase 2 (HK2), 6-phosphofructo-2-kinase/fructose-2,6-biphosphatase 3 (PFKFB3), and lactic acid in cells treated with TGF-β1. The oxygen consumption rate and the extracellular acidification rate were detected using Seahorse assays. Then, mitophagy was evaluated using transmission electron microscopy, mt-Keima, and the co-localization of Parkin and COX IV with LC3 and LAMP1, respectively. The autophagic degradation of HK2 and PFKFB3 was detected by 3MA and bafilomycin A1 and assessed by their co-localization with LC3 and LAMP1, respectively. The effects of ALA on LF activation markers collagen I and α-SMA were detected. The effects of ALA on glucose metabolism, mitophagy, and the activation of LF were also investigated in vivo.

RESULTS

We found that the ALA/MrgD axis improved TGF-β1-mediated LF activation by repressing glycolysis by downregulating HK2 and PFKFB3 expression. Lactic acid sustained positive feedback between glycolysis and LF activation by maintaining the expression of HK2 and PFKFB3. We also showed that glycolysis enhancement resulted from blocking the autophagic degradation of HK2 and PFKFB3 while upregulated mRNA levels by TGF-β1, while all of those improved by ALA adding. Importantly, we determined that moderation of Parkin/LC3-mediated mitophagy by TGF-β1 also promotes glycolysis but is reversed by ALA. Furthermore, we proved that ALA counteracts the effects of bleomycin on HK2, PFKFB3, LC3, Parkin, and LF activation in vivo.

CONCLUSION

In this study, we show that the ALA/MrgD axis prevents TGF-β1-mediated fibroblast activation via regulation of aerobic glycolysis and mitophagy.

Integrin β3 Mediates Sepsis and Mechanical Ventilation-Associated Pulmonary Fibrosis Through Glycometabolic Reprogramming

Mechanical ventilation (MV) has become a clinical first-line treatment option for patients with respiratory failure. However, it was unclear whether MV further aggravates the process of sepsis-associated pulmonary fibrosis and eventually leads to sepsis and mechanical ventilation-associated pulmonary fibrosis (S-MVPF). This study aimed to explore the mechanism of S-MVPF concerning integrin β3 activation in glycometabolic reprogramming of lung fibroblasts. We found that MV exacerbated sepsis-associated pulmonary fibrosis induced by lipopolysaccharide, which was accompanied by proliferation of lung fibroblasts, increased deposition of collagen in lung tissue, and increased procollagen type I carboxy-terminal propeptide in the bronchoalveolar lavage fluid. A large number of integrin β3- and pyruvate kinase M2-positive fibroblasts were detected in lung tissue after stimulation with lipopolysaccharide and MV, with an increase in lactate dehydrogenase A expression and lactate levels. S-MVPF was primarily attenuated in integrin β3-knockout mice, which also resulted in a decrease in the levels of pyruvate kinase M2, lactate dehydrogenase A, and lactate. In conclusion, MV aggravated sepsis-associated pulmonary fibrosis, with glycometabolic reprogramming mediated by integrin β3 activation. Thus, integrin β3-mediated glycometabolic reprogramming might be a potential therapeutic target for S-MVPF.

Pseudomonas aeruginosa utilizes the host-derived polyamine spermidine to facilitate antimicrobial tolerance

Pseudomonas aeruginosa undergoes diversification during infection of the cystic fibrosis (CF) lung. Understanding these changes requires model systems that capture the complexity of the CF lung environment. We previously identified loss-of-function mutations in the 2-component regulatory system sensor kinase gene pmrB in P. aeruginosa from CF lung infections and from experimental infection of mice. Here, we demonstrate that, while such mutations lowered in vitro minimum inhibitory concentrations for multiple antimicrobial classes, this was not reflected in increased antibiotic susceptibility in vivo. Loss of PmrB impaired aminoarabinose modification of LPS, increasing the negative charge of the outer membrane and promoting uptake of cationic antimicrobials. However, in vivo, this could be offset by increased membrane binding of other positively charged molecules present in lungs. The polyamine spermidine readily coated the surface of PmrB-deficient P. aeruginosa, reducing susceptibility to antibiotics that rely on charge differences to bind the outer membrane and increasing biofilm formation. Spermidine was elevated in lungs during P. aeruginosa infection in mice and during episodes of antimicrobial treatment in people with CF. These findings highlight the need to study antimicrobial resistance under clinically relevant environmental conditions. Microbial mutations carrying fitness costs in vitro may be advantageous during infection, where host resources can be utilized.

Metabolic signatures of immune cells in chronic kidney disease

Immune cells play a key role in maintaining renal dynamic balance and dealing with renal injury. The physiological and pathological functions of immune cells are intricately connected to their metabolic characteristics. However, immunometabolism in chronic kidney disease (CKD) is not fully understood. Pathophysiologically, disruption of kidney immune cells homeostasis causes inflammation and tissue damage via triggering metabolic reprogramming. The diverse metabolic characteristics of immune cells at different stages of CKD are strongly associated with their different pathological effect. In this work, we reviewed the metabolic characteristics of immune cells (macrophages, natural killer cells, T cells, natural killer T cells and B cells) and several non-immune cells, as well as potential treatments targeting immunometabolism in CKD. We attempt to elaborate on the metabolic signatures of immune cells and their intimate correlation with non-immune cells in CKD.

Oral Supplementation with the Polyamine Spermidine Affects Hepatic but Not Pulmonary Lipid Metabolism in Lean but Not Obese Mice

The polyamine spermidine is discussed as a caloric restriction mimetic and therapeutic option for obesity and related comorbidities. This study tested oral spermidine supplementation with regard to the systemic, hepatic and pulmonary lipid metabolism under different diet conditions. Male C57BL/6 mice were fed a purified control (CD), high sucrose (HSD) or high fat (HFD) diet with (-S) or without spermidine for 30 weeks. In CD-fed mice, spermidine decreased body and adipose tissue weights and reduced hepatic lipid content. The HSD induced hepatic lipid synthesis and accumulation and hypercholesterolemia. This was not affected by spermidine supplementation, but body weight and blood glucose were lower in HSD-S compared to HSD. HFD-fed mice showed higher body and fat depot weights, prediabetes, hypercholesterolemia and severe liver steatosis, which were not altered by spermidine. Within the liver, spermidine diminished hepatic expression of lipogenic transcription factors SREBF1 and 2 under HSD and HFD and affected the expression of other lipid-related enzymes. In contrast, diet and spermidine exerted only minor effects on pulmonary parameters. Thus, oral spermidine supplementation affects lipid metabolism in a diet-dependent manner, with significant reductions in body fat and weight under physiological nutrition and positive effects on weight and blood glucose under high sucrose intake, but no impact on dietary fat-related parameters.

Identification and immune characteristics of molecular subtypes related to fatty acid metabolism in idiopathic pulmonary fibrosis

Background

Although fatty acid metabolism has been confirmed to be involved in the pathological process of idiopathic pulmonary fibrosis (IPF), systematic analyses on the immune process mediated by fatty acid metabolism-related genes (FAMRGs) in IPF remain lacking.

Methods

The gene expression data of 315 patients with IPF were obtained from Gene Expression Omnibus database and were divided into the training and verification sets. The core FAMRGs of the training set were identified through weighted gene co-expression network analysis. Then, the fatty acid metabolism-related subtypes in IPF were identified on the basis of k-means unsupervised clustering. The scores of fatty acid metabolism and the expression of the fibrosis biomarkers in different subtypes were compared, and functional enrichment analysis was carried out on the differentially expressed genes between subtypes. A random forest model was used to select important FAMRGs as diagnostic markers for distinguishing between subtypes, and a line chart model was constructed and verified by using other datasets and rat models with different degrees of pulmonary fibrosis. The difference in immune cell infiltration among subtypes was evaluated with CIBERSORT, and the correlation between core diagnostic markers and immune cells were analyzed.

Results

Twenty-four core FAMRGs were differentially expressed between the training set and normal samples, and IPF was divided into two subtypes. Significant differences were observed between the two subtypes in biological processes, such as linoleic acid metabolism, cilium movement, and natural killer (NK) cell activation. The subtype with high fatty acid metabolism had more severe pulmonary fibrosis than the other subtype. A reliable construction line chart model based on six diagnostic markers was constructed, and ABCA3 and CYP24A1 were identified as core diagnostic markers. Significant differences in immune cell infiltration were found between the two subtypes, and ABCA3 and CYP24A1 were closely related to NK cells.

Conclusion

Fatty acid metabolism and the immune process that it mediates play an important role in the occurrence and development of IPF. The analysis of the role of FAMRGs in IPF may provide a new potential therapeutic target for IPF.

Systemic Sclerosis Association with Malignancy

The association of systemic sclerosis (SSc) and cancer is well known from several decades suggesting common genetic and environmental risk factors involved in the development of both diseases. Immunosuppressive drugs widely used in SSc may increase the risk of cancer occurrence and different SSc clinical and serological features identify patients at major risk to develop malignancy. In this context, among serological features, presence of anti-RNA polymerase III and anti-topoisomerase I autoantibodies seems to increase cancer frequency in SSc patients (particularly lung and breast cancers). Lung fibrosis and a long standing SSc pulmonary involvement have been largely proposed as lung cancer risk factors, and the exposure to cyclophosphamide and an upper gastrointestinal involvement have been traditionally linked to bladder and oesophagus cancers, respectively. Furthermore, immune checkpoint inhibitors used for cancer therapy can induce immune-related adverse events, which are more frequent and severe in patients with pre-existing autoimmune diseases such as SSc. The strong association between SSc and cancer occurrence steers clinicians to carefully survey SSc patients performing periodical malignancy screening. In the present review, the most relevant bilateral relationships between SSc and cancer will be addressed.

Endocannabinoid signalling/cannabinoid receptor 2 is involved in icariin-mediated protective effects against bleomycin-induced pulmonary fibrosis

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a progressive fibrotic disease of unknown aetiology with limited effective treatment options. It is important to explore novel therapeutic targets and develop potential drugs for IPF.

PURPOSE

The aim of the present study was to analyse nontargeted plasma metabolites in patients with IPF and investigate whether cannabinoid receptor (CB2) activation mediates the antifibrotic effect of icariin (ICA).

METHODS

We used an untargeted metabolomics method to detect the global metabolic profiles in the plasma of stable IPF patients and patients with stable chronic obstructive pulmonary disease (COPD), as well as healthy subjects. The untargeted liquid chromatography-mass spectrometry (LC-MS) analysis revealed that IPF showed differential metabolites and perturbed signalling pathways. ICA is pharmacologically bioactive and possesses extensive therapeutic capacities such as osteoprotective, neuroprotective, cardiovascular protective, anti-cancer, anti-inflammation and reproductive function. Therefore, ICA was administered to a pulmonary fibrosis rat model for 4 weeks and then the effect of ICA on pulmonary fibrosis was examined by dissection and histology.

RESULTS

The metabolites in the plasma were determined by untargeted LC-MS. An unsupervised principal component analysis (PCA) was used to observe the distribution of each sample, and a supervised partial least squares-discriminant analysis (PLS-DA) and orthogonal partial least squares-discriminant analysis (OPLS-DA) results showed that there was significant separation between any two groups. ROC curve analyses revealed that 8 metabolites with high AUCs above 0.7 between the three groups of plasma samples. Pathway enrichment analysis revealed that 3 metabolites are involved in retrograde endocannabinoid signalling. Meanwhile, Retrograde endocannabinoid signalling was identified significantly different in IPF group from other groups by Kyoto encyclopedia of Genes and Genomes (KEGG) pathway analysis, and then we further confirmed the endocannabinoid signalling by detecting the expression of the main receptors in bleomycin-induced pulmonary fibrosis, COPD rat model and normal rats. Consistent with previous studies, we found that the elevation of CB1 and CB2 in the lung tissues could be a signature of the pulmonary fibrosis rat model. Importantly, ICA may alleviate bleomycin-induced lung injury by decreasing CB1 and CB2 expression in the bleomycin-induced rat model.

CONCLUSION

Taken together, we measured the global metabolic profile of IPF patients and identified CB2 as a novel potential target. ICA treatment demonstrated outstanding therapeutic effects on bleomycin-induced pulmonary fibrosis and targeting on CB2 may be the main underlying mechanism. ICA is a promising drug candidate to cure pulmonary fibrosis and mediate antagonists of the CB2 receptor.

The treatment of Qibai Pingfei Capsule on chronic obstructive pulmonary disease may be mediated by Th17/Treg balance and gut-lung axis microbiota

BACKGROUND

Chronic obstructive pulmonary disease (COPD), a prevalent, progressive respiratory disease, has become the third leading cause of death globally. Increasing evidence suggests that intestinal and pulmonary microbiota dysbiosis is associated with COPD. Researchers have shown that T helper (Th) 17/regulatory T (Treg) imbalance is involved in COPD. Qibai Pingfei Capsule (QBPF) is a traditional Chinese medicine used to treat COPD clinically in China. However, the effects of QBPF intervention on the Th17/Treg balance and microbiota in the gut and lung are still poorly understood.

METHODS

This study divided the rats into three groups (n = 8): control, model, and QBPF group. After establishing the model of COPD for four weeks and administering of QBPF for two weeks, Th17 cells, Treg cells, their associated cytokines, transcription factors, and intestinal and pulmonary microbiota of rats were analyzed. Furthermore, the correlations between intestinal and pulmonary microbiota and between bacterial genera and pulmonary function and immune function were measured.

RESULTS

The results revealed that QBPF could improve pulmonary function and contribute to the new balance of Th17/Treg in COPD rats. Meanwhile, QBPF treatment could regulate the composition of intestinal and pulmonary microbiota and improve community structure in COPD rats, suppressing the relative abundance of Coprococcus_2, Prevotella_9, and Blautia in the gut and Mycoplasma in the lung, but accumulating the relative abundance of Prevotellaceae_UCG_003 in the gut and Rikenellaceae_RC9_gut_group in the lung. Additionally, gut-lung axis was confirmed by the significant correlations between the intestinal and pulmonary microbiota. Functional analysis of microbiota showed amino acid metabolism was altered in COPD rats in the gut and lung. Spearman correlation analysis further enriched the relationship between the microbiota in the gut and lung and pulmonary function and immune function in COPD model rats.

CONCLUSIONS

Our study indicated that the therapeutic effects of QBPF may be achieved by maintaining the immune cell balance and regulating the gut-lung axis microbiota, providing references to explore the potential biomarkers of COPD and the possible mechanism of QBPF to treat COPD.

A Metabolomics Approach to Sulforaphane Efficacy in Secondhand Smoking-Induced Pulmonary Damage in Mice

Sulforaphane is an isocyanate abundantly present in cruciferous vegetables. In the present study, we aimed to investigate the effects of sulforaphane on secondhand smoking (SHS)-induced pulmonary damage in mice. Additionally, a metabolomic study was performed to identify biomarkers associated with pulmonary disease using proton nuclear magnetic resonance (1H-NMR) analysis. Male C57BL6J mice were divided into a control group, an SHS exposure group (positive control group, PC), and a sulforaphane treatment group exposed to secondhand smoke (SS) (n = 5 per group). The PC and SS groups were exposed to secondhand smoke in a chamber twice daily for four weeks. Mice in the SS group were orally administered sulforaphane (50 mg/kg) for four weeks during secondhand smoke exposure. Histopathological examination of the lungs revealed pulmonary damage in PC mice, including loss of bronchial epithelial cells, bronchial wall thickening, and infiltration of macrophages. In contrast, mice in the SS group showed little or no epithelial thickening, thereby exhibiting reduced lung damage. Mouse serum and lung tissues were collected and analyzed to determine changes in endogenous metabolites using 1H-NMR. After target profiling, we identified metabolites showing the same tendency in the serum and lung as biomarkers for SHS-induced pulmonary damage, including taurine, glycerol, creatine, arginine, and leucine. As a result of histopathological examination, sulforaphane might inhibit SHS-induced lung damage, and metabolite analysis results suggest potential biomarkers for SHS-induced pulmonary damage in mice.