Identification of the lipid biomarkers from plasma in idiopathic pulmonary fibrosis by Lipidomics

Plasma and platelet lipidome changes in Fabry disease

BACKGROUND

Fabry disease (FD) is an X-linked lysosomal storage disorder characterized by the progressive accumulation of globotriaosylceramide (Gb3) leading to systemic manifestations such as chronic kidney disease, cardiomyopathy, and stroke. There is still a need for novel markers for improved FD screening and prognosis. Moreover, the pathological mechanisms in FD, which also include systemic inflammation and fibrosis, are not yet fully understood.

METHODS

Plasma and platelets were obtained from 11 ERT (enzyme-replacement therapy)-treated symptomatic, 4 asymptomatic FD patients, and 13 healthy participants. A comprehensive targeted lipidomics analysis was conducted quantitating more than 550 lipid species.

RESULTS

Sphingadiene (18:2;O2)-containing sphingolipid species, including Gb3 and galabiosylceramide (Ga2), were significantly increased in FD patients. Plasma levels of lyso-dihexosylceramides, sphingoid base 1-phosphates (S1P), and GM3 ganglioside were also altered in FD patients, as well as specific plasma ceramide ratios used in cardiovascular disease risk prediction. Gb3 did not increase in patients' platelets but displayed a high inter-individual variability in patients and healthy participants. Platelets accumulated, however, lyso-Gb3, acylcarnitines, C16:0-sphingolipids, and S1P.

CONCLUSIONS

This study identified lipidome changes in plasma and platelets from FD patients, a possible involvement of platelets in FD, and potential new markers for screening and monitoring of this disease.

Exploring the causal effect between lipid-modifying drugs and idiopathic pulmonary fibrosis: a drug-target Mendelian randomization study

BACKGROUND

Idiopathic pulmonary fibrosis (IPF) is a respiratory disorder of obscure etiology and limited treatment options, possibly linked to dysregulation in lipid metabolism. While several observational studies suggest that lipid-lowering agents may decrease the risk of IPF, the evidence is inconsistent. The present Mendelian randomization (MR) study aims to determine the association between circulating lipid traits and IPF and to assess the potential influence of lipid-modifying medications for IPF.

METHODS

Summary statistics of 5 lipid traits (high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, triglyceride, apolipoprotein A, and apolipoprotein B) and IPF were sourced from the UK Biobank and FinnGen Project Round 10. The study's focus on lipid-regulatory genes encompassed PCSK9, NPC1L1, ABCG5, ABCG8, HMGCR, APOB, LDLR, CETP, ANGPTL3, APOC3, LPL, and PPARA. The primary effect estimates were determined using the inverse-variance-weighted method, with additional analyses employing the contamination mixture method, robust adjusted profile score, the weighted median, weighted mode methods, and MR-Egger. Summary-data-based Mendelian randomization (SMR) was used to confirm significant lipid-modifying drug targets, leveraging data on expressed quantitative trait loci in relevant tissues. Sensitivity analyses included assessments of heterogeneity, horizontal pleiotropy, and leave-one-out methods.

RESULTS

There was no significant effect of blood lipid traits on IPF risk (all P＞0.05). Drug-target MR analysis indicated that genetic mimicry for inhibitor of NPC1L1, PCSK9, ABCG5, ABCG8, and APOC3 were associated with increased IPF risks, with odds ratios (ORs) and 95% confidence intervals (CIs) as follows: 2.74 (1.05-7.12, P = 0.039), 1.36 (1.02-1.82, P = 0.037), 1.66 (1.12-2.45, P = 0.011), 1.68 (1.14-2.48, P = 0.009), and 1.42 (1.20-1.67, P = 3.17×10-5), respectively. The SMR method identified a significant association between PCSK9 gene expression in whole blood and reduced IPF risk (OR = 0.71, 95% CI: 0.50-0.99, P = 0.043). Sensitivity analyses showed no evidence of bias.

CONCLUSIONS

Serum lipid traits did not significantly affect the risk of idiopathic pulmonary fibrosis. Drug targets MR studies examining 12 lipid-modifying drugs indicated that PCSK9 inhibitors could dramatically increase IPF risk, a mechanism that may differ from their lipid-lowering actions and thus warrants further investigation.

Blood lipid profiles as a prognostic biomarker in idiopathic pulmonary fibrosis

BACKGROUND

Dysregulation of lipid metabolism is implicated in the pathogenesis of idiopathic pulmonary fibrosis (IPF). However, the association between the blood lipid profiles and the prognosis of IPF is not well defined. We aimed to identify the impacts of lipid profiles on prognosis in patients with IPF.

METHODS

Clinical data of 371 patients with IPF (145 and 226 in the derivation and validation cohorts, respectively), including serum lipid profiles (total cholesterol, triglyceride, high-density lipoprotein cholesterol, low-density lipoprotein cholesterol, apolipoprotein A-I [Apo A-I], and apolipoprotein B), were retrospectively collected. The association with mortality was analyzed using the Cox proportional hazard model.

RESULTS

In the derivation cohort, the mean age was 67.5 years, 86.2% were men, and 30.3% died during the follow-up (median: 18.0 months). Non-survivors showed lower lung function and greater gender-age-physiology scores than survivors. Among the serum lipid profiles, the levels of triglyceride and Apo A-I were significantly lower in non-survivors than in survivors. In the multivariate Cox analysis, low Apo A-I levels (< 140 mg/dL) were independently associated with the risk of mortality (hazard ratio 3.910, 95% confidence interval 1.170-13.069; P = 0.027), when adjusted for smoking history, body mass index, GAP score, and antifibrotic agent use. In both derivation and validation cohorts, patients with low Apo A-I levels (< 140 mg/dL) had worse survival (median survival: [derivation] 34.0 months vs. not reached, P = 0.003; [validation] 40.0 vs. 53.0 months, P = 0.027) than those with high Apo A-I levels in the Kaplan-Meier survival analysis.

CONCLUSIONS

Our results indicate that low serum Apo A-1 levels are an independent predictor of mortality in patients with IPF, suggesting the utility of serum Apo A-I as a prognostic biomarker in IPF.

Yinhuang buccal tablet alters airway microbiota composition and metabolite profile in healthy humans

ETHNOPHARMACOLOGICAL RELEVANCE

Perturbations in airway microbiota composition and disruption of microbe-metabolite interactions have been observed in respiratory infectious diseases (RIDs). The Yinhuang (YH) buccal tablet, as an ancient Chinese medicinal formula, has been traditionally employed for the management of upper RIDs. However, there is a lack of evidence for the effects of YH buccal tablets on upper respiratory tract microbiota and circulating metabolites.

AIM OF THE STUDY

The aim of this study was to analyze the changes in respiratory microbiota composition and circulating metabolite profile after YH buccal tablets administration.

MATERIALS AND METHODS

Throat swab samples and serum samples were collected from 60 healthy subjects for high-throughput 16S ribosomal RNA gene (16S rRNA) sequencing and non-targeted Ultra-high performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) analysis.

RESULTS

Airway microbial composition changed significantly after YH administration. The abundance of Actinomyces and Prevotella_7 increased, while the abundance of potentially pathogenic Pseudomonas and Corynebacterium decreased. A total of 168 significant HMDB taxonomic metabolites were identified in serum samples, of which lipid metabolites accounted for the largest proportion. Correlation analysis showed that circulatory metabolites were significantly correlated with changes in airway microbiota composition.

CONCLUSIONS

YH buccal tablets can inhibit opportunistic pathogens, increase beneficial microorganisms in the upper respiratory tract, and regulate the body's metabolic pathways. These findings provide insights into the mechanism of action of YH buccal tablets in the treatment and prevention of respiratory diseases.

Lipids in Equine Airway Inflammation: An Overview of Current Knowledge

Mild-moderate and severe equine asthma (MEA and SEA) are prevalent inflammatory airway conditions affecting horses of numerous breeds and disciplines. Despite extensive research, detailed disease pathophysiology and the differences between MEA and SEA are still not completely understood. Bronchoalveolar lavage fluid cytology, broadly used in clinical practice and in equine asthma research, has limited means to represent the inflammatory status in the lower airways. Lipidomics is a field of science that can be utilized in investigating cellular mechanisms and cell-to-cell interactions. Studies in lipidomics have a broad variety of foci, of which fatty acid and lipid mediator profile analyses and global lipidomics have been implemented in veterinary medicine. As many crucial proinflammatory and proresolving mediators are lipids, lipidomic studies offer an interesting yet largely unexplored means to investigate inflammatory reactions in equine airways. The aim of this review article is to collect and summarize the findings of recent lipidomic studies on equine airway inflammation.

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.

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.

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.

Sirtuin 6 ameliorates bleomycin-induced pulmonary fibrosis via activation of lipid catabolism

Pulmonary fibrosis is a chronic and serious interstitial lung disease with little effective therapies currently. Our incomplete understanding of its pathogenesis remains obstacles in therapeutic developments. Sirtuin 6 (SIRT6) has been shown to mitigate multiple organic fibrosis. However, the involvement of SIRT6-mediated metabolic regulation in pulmonary fibrosis remains unclear. Here, we demonstrated that SIRT6 was predominantly expressed in alveolar epithelial cells in human lung tissues by using a single-cell sequencing database. We showed that SIRT6 protected against bleomycin-induced injury of alveolar epithelial cells in vitro and pulmonary fibrosis of mice in vivo. High-throughput sequencing revealed enriched lipid catabolism in Sirt6 overexpressed lung tissues. Mechanismly, SIRT6 ameliorates bleomycin-induced ectopic lipotoxicity by enhancing lipid degradation, thereby increasing the energy supply and reducing the levels of lipid peroxides. Furthermore, we found that peroxisome proliferator-activated receptor α (PPARα) was essential for SIRT6-mediated lipid catabolism, anti-inflammatory responses, and antifibrotic signaling. Our data suggest that targeting SIRT6-PPARα-mediated lipid catabolism could be a potential therapeutic strategy for diseases complicated with pulmonary fibrosis.

Metabolomics unveils the exacerbating role of arachidonic acid metabolism in atherosclerosis

Atherosclerosis is a complex vascular disorder characterized by the deposition of lipids, inflammatory cascades, and plaque formation in arterial walls. A thorough understanding of its causes and progression is necessary to develop effective diagnostic and therapeutic strategies. Recent breakthroughs in metabolomics have provided valuable insights into the molecular mechanisms and genetic factors involved in atherosclerosis, leading to innovative approaches for preventing and treating the disease. In our study, we analyzed clinical serum samples from both atherosclerosis patients and animal models using laser desorption ionization mass spectrometry. By employing methods such as orthogonal partial least-squares discrimination analysis (OPLS-DA), heatmaps, and volcano plots, we can accurately classify atherosclerosis (AUC = 0.892) and identify key molecules associated with the disease. Specifically, we observed elevated levels of arachidonic acid and its metabolite, leukotriene B4, in atherosclerosis. By inhibiting arachidonic acid and monitoring its downstream metabolites, we discovered the crucial role of this metabolic pathway in regulating atherosclerosis. Metabolomic research provides detailed insights into the metabolic networks involved in atherosclerosis development and reveals the close connection between abnormal metabolism and the disease. These studies offer new possibilities for precise diagnosis, treatment, and monitoring of disease progression, as well as evaluating the effectiveness of therapeutic interventions.

Integrating fecal metabolomics and intestinal microbiota to study the mechanism of cannabidiol in the treatment of idiopathic pulmonary fibrosis

Introduction: Idiopathic pulmonary fibrosis is a chronic interstitial lung disease characterized by excessive deposition of extracellular matrix. Cannabidiol, a natural component extracted from plant cannabis, has been shown to have therapeutic effects on lung diseases, but its exact mechanism of action is unknown, hindering its therapeutic effectiveness. Methods: To establish a pulmonary fibrosis model, combined with UPLC-Q-TOF/MS metabolomics and 16S rDNA sequencing, to explore cannabidiol's mechanism in treating pulmonary fibrosis. The rats were randomly divided into the control group, pulmonary fibrosis model group, prednisone treatment group, and cannabidiol low, medium, and high dose groups. The expression levels of HYP, SOD, and MDA in lung tissue and the expression levels of TNF-α, IL-1β, and IL-6 in serum were detected. Intestinal microbiota was detected using UPLC-QTOF/MS analysis of metabolomic properties and 16S rDNA sequencing. Results: Pathological studies and biochemical indexes showed that cannabidiol treatment could significantly alleviate IPF symptoms, significantly reduce the levels of TNF-α, IL-1β, IL-6, MDA, and HYP, and increase the expression level of SOD (p < 0.05). CBD-H can regulate Lachnospiraceae_NK4A136_group, Pseudomonas, Clostridia_UCG-014, Collinsella, Prevotella, [Eubacterium]_coprostanoligenes_group, Fusobacterium, Ruminococcus, and Streptococcus, it can restore intestinal microbiota function and reverse fecal metabolism trend. It also plays the role of fibrosis through the metabolism of linoleic acid, glycerol, linolenic acid, and sphingolipid. Discussion: Cannabidiol reverses intestinal microbiota imbalance and attenuates pulmonary fibrosis in rats through anti-inflammatory, antioxidant, and anti-fibrotic effects. This study lays the foundation for future research on the pathological mechanisms of IPF and the development of new drug candidates.

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 .

Lipidomics reveals serum lipid metabolism disorders in CTD-induced liver injury

BACKGROUND

Cantharidin (CTD), the main toxic component of Mylabris, has been extensively used for tumor treatment in recent years. CTD-induced liver toxicity has attracted significant interest in clinic.

METHODS

In this study, biochemical parameters and liver pathological changes were analyzed after CTD was administered to mice by gavage. Subsequently, a lipidomic approach was used to investigate serum lipid metabolism disorders, and the mechanism underlying CTD-induced liver injury in mice was explored.

RESULTS

The results showed that the levels of TC and LDL-C were significantly increased after CTD intervention. Besides, pathological results showed inflammatory cell infiltration and hepatocyte necrosis in the liver. Furthermore, lipidomics found that a total of 18 lipid metabolites were increased and 40 were decreased, including LPC(20:4), LPC(20:3), PC(22:6e/2:0), PE(14:0e/21:2), PC(18:2e/22:6), glycerophospholipids, CE(16:0), CE(18:0) Cholesterol esters and TAG(12:0/12:0/22:3), TAG(16:1/16:2/20:4), TAG(18:1/18:1/20:0), TAG(16:2/18:2/18:2), TAG(18:0/18:0/20:0), TAG(13:1/19:0/19:0) glycerolipids. Metabolic pathway analysis found that glycerophospholipid, glycerol ester and glycosylphosphatidylinositol (GPI)-anchored biosynthetic metabolic pathways were dysregulated and the increase in PE caused by glycophoric metabololism and GPI may be the source of lipid metabolism disorders caused by CTD. Overall, the present study provided new insights into the mechanism of CTD-induced liver injury and increased drug safety during clinical application.

Plasma metabolomics and quantitative interstitial abnormalities in ever-smokers

BACKGROUND

Quantitative interstitial abnormalities (QIA) are an automated computed tomography (CT) finding of early parenchymal lung disease, associated with worse lung function, reduced exercise capacity, increased respiratory symptoms, and death. The metabolomic perturbations associated with QIA are not well known. We sought to identify plasma metabolites associated with QIA in smokers. We also sought to identify shared and differentiating metabolomics features between QIA and emphysema, another smoking-related advanced radiographic abnormality.

METHODS

In 928 former and current smokers in the Genetic Epidemiology of COPD cohort, we measured QIA and emphysema using an automated local density histogram method and generated metabolite profiles from plasma samples using liquid chromatography-mass spectrometry (Metabolon). We assessed the associations between metabolite levels and QIA using multivariable linear regression models adjusted for age, sex, body mass index, smoking status, pack-years, and inhaled corticosteroid use, at a Benjamini-Hochberg False Discovery Rate p-value of ≤ 0.05. Using multinomial regression models adjusted for these covariates, we assessed the associations between metabolite levels and the following CT phenotypes: QIA-predominant, emphysema-predominant, combined-predominant, and neither- predominant. Pathway enrichment analyses were performed using MetaboAnalyst.

RESULTS

We found 85 metabolites significantly associated with QIA, with overrepresentation of the nicotinate and nicotinamide, histidine, starch and sucrose, pyrimidine, phosphatidylcholine, lysophospholipid, and sphingomyelin pathways. These included metabolites involved in inflammation and immune response, extracellular matrix remodeling, surfactant, and muscle cachexia. There were 75 metabolites significantly different between QIA-predominant and emphysema-predominant phenotypes, with overrepresentation of the phosphatidylethanolamine, nicotinate and nicotinamide, aminoacyl-tRNA, arginine, proline, alanine, aspartate, and glutamate pathways.

CONCLUSIONS

Metabolomic correlates may lend insight to the biologic perturbations and pathways that underlie clinically meaningful quantitative CT measurements like QIA in smokers.

An Analysis of Targeted Serum Lipidomics in Patients with Pneumoconiosis - China, 2022

Introduction

Pneumoconiosis emerges as the most critical and prevalent occupational disease in China at present, according to research. Studies indicate that pneumoconiosis may indeed impact the body's phospholipid metabolism.

Methods

In this study, serum samples were taken from 46 paired participants, which included patients with pneumoconiosis and dust-exposed workers. We employed ultra-performance liquid chromatography-tandem mass spectrometry (UPLC-MS/MS) technology in targeted lipidomics to investigate serum target phospholipids. Initially, a pilot study was conducted with a selection of 24 pneumoconiosis patients and 24 dust-exposed workers, using both univariate and multivariate statistical analyses to preliminarily identify significant differences in phospholipids. Subsequent to this, the remaining subjects were engaged in a validation study, wherein receiver operating characteristic (ROC) analysis was performed to further substantiate the screening potency of potential lipid biomarkers for pneumoconiosis.

Results

The pilot study revealed significantly reduced serum levels of 16∶0 lysophosphatidylcholines (Lyso PC), 18∶0-18∶1 phosphatidylglycerol (PG), 18∶0-18∶1 phosphatidylethanolamine (PE), 18∶0 PE, and 18∶1 lysophosphatidylethanolamine（Lyso PE) in the case group in comparison to the control group. Additionally, 18∶0 PE, 18∶0-18∶1 PE, and 18∶1 Lyso PE emerged as significant phospholipids with superior diagnostic values [area under the curve (AUC)>0.7]. A diagnostic model was established, built on 16∶0 PC and 18∶0 PE (AUC>0.8). In the ROC analyses of validation studies, the 18∶0-18∶1 PE and this diagnostic model demonstrated excellent screening efficiency (AUC>0.7).

Discussion

A significant divergence in phospholipid metabolism has been observed between pneumoconiosis patients and dust-exposed workers. The 18∶0-18∶1 PE present in serum could potentially function as a lipid biomarker for pneumoconiosis. Additionally, diagnostic models were developed relying on 16∶0 PC and 18∶0 PE, proving to have superior screening efficiency.

Lipid metabolism in idiopathic pulmonary fibrosis: From pathogenesis to therapy

Idiopathic pulmonary fibrosis (IPF) is a chronic irreversible interstitial lung disease characterized by a progressive decline in lung function. The etiology of IPF is unknown, which poses a significant challenge to the treatment of IPF. Recent studies have identified a strong association between lipid metabolism and the development of IPF. Qualitative and quantitative analysis of small molecule metabolites using lipidomics reveals that lipid metabolic reprogramming plays a role in the pathogenesis of IPF. Lipids such as fatty acids, cholesterol, arachidonic acid metabolites, and phospholipids are involved in the onset and progression of IPF by inducing endoplasmic reticulum stress, promoting cell apoptosis, and enhancing the expression of pro-fibrotic biomarkers. Therefore, targeting lipid metabolism can provide a promising therapeutic strategy for pulmonary fibrosis. This review focuses on lipid metabolism in the pathogenesis of pulmonary fibrosis.

The lung mesenchyme in development, regeneration, and fibrosis

Mesenchymal cells are uniquely located at the interface between the epithelial lining and the stroma, allowing them to act as a signaling hub among diverse cellular compartments of the lung. During embryonic and postnatal lung development, mesenchyme-derived signals instruct epithelial budding, branching morphogenesis, and subsequent structural and functional maturation. Later during adult life, the mesenchyme plays divergent roles wherein its balanced activation promotes epithelial repair after injury while its aberrant activation can lead to pathological remodeling and fibrosis that are associated with multiple chronic pulmonary diseases, including bronchopulmonary dysplasia, idiopathic pulmonary fibrosis, and chronic obstructive pulmonary disease. In this Review, we discuss the involvement of the lung mesenchyme in various morphogenic, neomorphogenic, and dysmorphogenic aspects of lung biology and health, with special emphasis on lung fibroblast subsets and smooth muscle cells, intercellular communication, and intrinsic mesenchymal mechanisms that drive such physiological and pathophysiological events throughout development, homeostasis, injury repair, regeneration, and aging.

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.

Lipid dysregulation associated with progression of silica-induced pulmonary fibrosis

Silicosis is an irreversible, progressive, fibrotic lung disease caused by long-term exposure to dust-containing silica particles at the workplace. Despite the precautions enforced, the rising incidence of silicosis continues to occur globally, particularly in developing countries. A better understanding of the disease progression and potential metabolic reprogramming of silicosis is warranted. The low- or high-dose silica-induced pulmonary fibrosis in mice was constructed to mimic chronic or accelerated silicosis. Silica-induced mice lung fibrosis was analyzed by histology, lung function, and computed tomography scans. Non-targeted metabolomics of the lung tissues was conducted by ultra-high-performance liquid chromatography-mass spectrometry to show the temporal metabolic trajectory. The low-dose silica-induced silicosis characterized inflammation for up to 42 days, with the onset of cellular silicon nodules. Conversely, the high-dose silica-induced silicosis characterized inflammation for up to 14 days, after which the disease developed rapidly, with a large volume of collagen deposition, presenting progressive massive fibrosis. Both low- and high silica-induced fibrosis had aberrant lipid metabolism. Combined with the RNA-Seq data, this multiomics study demonstrated alterations in the enzymes involved in sphingolipid metabolism. Time-dependent metabolic reprogramming revealing abnormal glycerophospholipid metabolism was intimately associated with the process of inflammation, whereas sphingolipid metabolism was crucial during lung fibrosis. These findings suggest that lipid dysregulation, especially sphingolipid metabolism, was involved in the process of silicosis.

Cellular and Molecular Control of Lipid Metabolism in Idiopathic Pulmonary Fibrosis: Clinical Application of the Lysophosphatidic Acid Pathway

Idiopathic pulmonary fibrosis (IPF) is a representative disease that causes fibrosis of the lungs. Its pathogenesis is thought to be characterized by sustained injury to alveolar epithelial cells and the resultant abnormal tissue repair, but it has not been fully elucidated. IPF is currently difficult to cure and is known to follow a chronic progressive course, with the patient's survival period estimated at about three years. The disease occasionally exacerbates acutely, leading to a fatal outcome. In recent years, it has become evident that lipid metabolism is involved in the fibrosis of lungs, and various reports have been made at the cellular level as well as at the organic level. The balance among eicosanoids, sphingolipids, and lipid composition has been reported to be involved in fibrosis, with particularly close attention being paid to a bioactive lipid "lysophosphatidic acid (LPA)" and its pathway. LPA signals are found in a wide variety of cells, including alveolar epithelial cells, vascular endothelial cells, and fibroblasts, and have been reported to intensify pulmonary fibrosis via LPA receptors. For instance, in alveolar epithelial cells, LPA signals reportedly induce mitochondrial dysfunction, leading to epithelial damage, or induce the transcription of profibrotic cytokines. Based on these mechanisms, LPA receptor inhibitors and the metabolic enzymes involved in LPA formation are now considered targets for developing novel means of IPF treatment. Advances in basic research on the relationships between fibrosis and lipid metabolism are opening the path to new therapies targeting lipid metabolism in the treatment of IPF.

Roles of lipid metabolism and its regulatory mechanism in idiopathic pulmonary fibrosis: A review

Idiopathic pulmonary fibrosis is a progressive lung disease of unknown etiology characterized by distorted distal lung architecture, inflammation, and fibrosis. Several lung cell types, including alveolar epithelial cells and fibroblasts, have been implicated in the development and progression of fibrosis. However, the pathogenesis of idiopathic pulmonary fibrosis is still incompletely understood. The latest research has found that dysregulation of lipid metabolism plays an important role in idiopathic pulmonary fibrosis. The changes in the synthesis and activity of fatty acids, cholesterol and other lipids seriously affect the regenerative function of alveolar epithelial cells and promote the transformation of fibroblasts into myofibroblasts. Mitochondrial function is the key to regulating the metabolic needs of a variety of cells, including alveolar epithelial cells. Sirtuins located in mitochondria are essential to maintain mitochondrial function and cellular metabolic homeostasis. Sirtuins can maintain normal lipid metabolism by regulating respiratory enzyme activity, resisting oxidative stress, and protecting mitochondrial function. In this review, we aimed to discuss the difference between normal and idiopathic pulmonary fibrosis lungs in terms of lipid metabolism. Additionally, we highlight recent breakthroughs on the effect of abnormal lipid metabolism on idiopathic pulmonary fibrosis, including the effects of sirtuins. Idiopathic pulmonary fibrosis has its high mortality and limited therapeutic options; therefore, we believe that this review will help to develop a new therapeutic direction from the aspect of lipid metabolism in idiopathic pulmonary fibrosis.

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.

Changes in serum metabolomics in idiopathic pulmonary fibrosis and effect of approved antifibrotic medication

Idiopathic pulmonary fibrosis (IPF) is a progressive disease with significant mortality and morbidity. Approval of antifibrotic therapy has ameliorated disease progression, but therapy response is heterogeneous and to date, adequate biomarkers predicting therapy response are lacking. In recent years metabolomic technology has improved and is broadly applied in cancer research thus enabling its use in other fields. Recently both aberrant metabolic and lipidomic pathways have been described to influence profibrotic responses. We thus aimed to characterize the metabolomic and lipidomic changes between IPF and healthy volunteers (HV) and analyze metabolomic changes following treatment with nintedanib and pirfenidone. We collected serial serum samples from two IPF cohorts from Germany (n = 122) and Spain (n = 21) and additionally age-matched healthy volunteers (n = 16). Metabolomic analysis of 630 metabolites covering 14 small molecule and 12 different lipid classes was carried out using flow injection analysis tandem mass spectrometry for lipids and liquid chromatography tandem mass spectrometry for small molecules. Levels were correlated with survival and disease severity. We identified 109 deregulated analytes in IPF compared to HV in cohort 1 and 112 deregulated analytes in cohort 2. Metabolites which were up-regulated in both cohorts were mainly triglycerides while the main class of down-regulated metabolites were phosphatidylcholines. Only a minority of de-regulated analytes were small molecules. Triglyceride subclasses were inversely correlated with baseline disease severity (GAP-score) and a clinical compound endpoint of lung function decline or death. No changes in the metabolic profiles were observed following treatment with pirfenidone. Nintedanib treatment induced up-regulation of triglycerides and phosphatidylcholines. Patients in whom an increase in these metabolites was observed showed a trend towards better survival using the 2-years composite endpoint (HR 2.46, p = 0.06). In conclusion, we report major changes in metabolites in two independent cohorts testing a large number of patients. Specific lipidic metabolite signatures may serve as biomarkers for disease progression or favorable treatment response to nintedanib.

State of the Art in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a form of usual interstitial pneumonia (UIP), though its origin is unknown [...]

Transcriptional Profiling of Insulin-like Growth Factor Signaling Components in Embryonic Lung Development and Idiopathic Pulmonary Fibrosis

Insulin-like growth factor (IGF) signaling controls the development and growth of many organs, including the lung. Loss of function of Igf1 or its receptor Igf1r impairs lung development and leads to neonatal respiratory distress in mice. Although many components of the IGF signaling pathway have shown to be dysregulated in idiopathic pulmonary fibrosis (IPF), the expression pattern of such components in different cellular compartments of the developing and/or fibrotic lung has been elusive. In this study, we provide a comprehensive transcriptional profile for such signaling components during embryonic lung development in mice, bleomycin-induced pulmonary fibrosis in mice and in human IPF lung explants. During late gestation, we found that Igf1 is upregulated in parallel to Igf1r downregulation in the lung mesenchyme. Lung tissues derived from bleomycin-treated mice and explanted IPF lungs revealed upregulation of IGF1 in parallel to downregulation of IGF1R, in addition to upregulation of several IGF binding proteins (IGFBPs) in lung fibrosis. Finally, treatment of IPF lung fibroblasts with recombinant IGF1 led to myogenic differentiation. Our data serve as a resource for the transcriptional profile of IGF signaling components and warrant further research on the involvement of this pathway in both lung development and pulmonary disease.

Connective Tissue Growth Factor in Idiopathic Pulmonary Fibrosis: Breaking the Bridge

CTGF is upregulated in patients with idiopathic pulmonary fibrosis (IPF), characterized by the deposition of a pathological extracellular matrix (ECM). Additionally, many omics studies confirmed that aberrant cellular senescence-associated mitochondria dysfunction and metabolic reprogramming had been identified in different IPF lung cells (alveolar epithelial cells, alveolar endothelial cells, fibroblasts, and macrophages). Here, we reviewed the role of the CTGF in IPF lung cells to mediate anomalous senescence-related metabolic mechanisms that support the fibrotic environment in IPF.

Disturbance of serum lipid metabolites and potential biomarkers in the Bleomycin model of pulmonary fibrosis in young mice

Background

Altered metabolic pathways have recently been considered as potential drivers of idiopathic pulmonary fibrosis (IPF) for the study of drug therapeutic targets. However, our understanding of the metabolite profile during IPF formation is lacking.

Methods

To comprehensively characterize the metabolic disorders of IPF, a mouse IPF model was constructed by intratracheal injection of bleomycin into C57BL/6J male mice, and lung tissues from IPF mice at 7 days, 14 days, and controls were analyzed by pathology, immunohistochemistry, and Western Blots. Meanwhile, serum metabolite detections were conducted in IPF mice using LC–ESI–MS/MS, KEGG metabolic pathway analysis was applied to the differential metabolites, and biomarkers were screened using machine learning algorithms.

Results

We analyzed the levels of 1465 metabolites and found that more than one-third of the metabolites were altered during IPF formation. There were 504 and 565 metabolites that differed between M7 and M14 and controls, respectively, while 201 differential metabolites were found between M7 and M14. In IPF mouse sera, about 80% of differential metabolite expression was downregulated. Lipids accounted for more than 80% of the differential metabolite species with down-regulated expression. The KEGG pathway enrichment analysis of differential metabolites was mainly enriched to pathways such as the metabolism of glycerolipids and glycerophospholipids. Eight metabolites were screened by a machine learning random forest model, and receiver operating characteristic curves (ROC) assessed them as ideal diagnostic tools.

Conclusions

In conclusion, we have identified disturbances in serum lipid metabolism associated with the formation of pulmonary fibrosis, contributing to the understanding of the pathogenesis of pulmonary fibrosis.

Supplementary Information

The online version contains supplementary material available at 10.1186/s12890-022-01972-6.

Lipidomics Profiling of HepG2 Cells and Interference by Mycotoxins Based on UPLC-TOF-IMS

Discovering the fungus-infected or mycotoxin-contaminated biomarkers is significant for systems biology since the metabolites in biological samples have significant polarity differences in both stochastic gene expression and microenvironmental change. Here, we aim to establish a comprehensive method for a lipidome by ion mobility mass spectrometry (IMS) merged with chemometrics to accurately find out the more scientific markers of cell interference by mycotoxins and for pathogenesis exploration and drug development. The differences in the abundances of several small molecules found in these metabolites were explored through multivariate statistical analysis, including principal component analysis (PCA) and orthogonal partial least-squares discriminant analysis (OPLS-DA), to further screen biomarkers. Good applicability and predictability were demonstrated by R²(X) and Q² (R² = 0.959, Q² = 0.999). Five compounds with m/z values of 512.502 8, 540.5343, 722.525 8, 787.667 5, and 813.683 0 were selected as markers, and four of them were further confirmed by chemical standards (i.e., MSMS of m/z 813.683 0 covering m/z 86.0978, 125.0008, 184.0745, and 185.0781). In summary, we demonstrated the integration of UPLC-TOF-IMS and the chemometrics approach to elucidate identified biomarkers, which also provides a new way of thinking for covering lipid biomarkers or prognostic indicators for mycotoxins.

Quantitative Lipidomic Analysis of Takotsubo Syndrome Patients' Serum

Takotsubo syndrome (TTS), also known as the transient left ventricular apical ballooning syndrome, is in contemporary times known as novel acute cardiac syndrome. It is characterized by transient left ventricular apical akinesis and hyperkinesis of the basal left ventricular portions. Although the precise etiology of TTS is unknown, events like the sudden release of stress hormones, such as the catecholamines and the increased inflammatory status might be plausible causes leading to the cardiovascular pathologies. Recent studies have highlighted that an imbalance in lipid accumulation might promote a deviant immune response as observed in TTS. However, there is no information on comprehensive profiling of serum lipids of TTS patients. Therefore, we investigated a detailed quantitative lipid analysis of TTS patients using ES-MSI. Our results showed significant differences in the majority of lipid species composition in the TTS patients compared to the control group. Furthermore, the computational analyses presented was able to link the altered lipids to the pro-inflammatory cytokines and disseminate possible mechanistic pathways involving TNFα and IL-6. Taken together, our study provides an extensive quantitative lipidome of TTS patients, which may provide a valuable Pre-diagnostic tool. This would facilitate the elucidation of the underlying mechanisms of the disease and to prevent the development of TTS in the future.

Pemafibrate attenuates pulmonary fibrosis by inhibiting myofibroblast differentiation

BACKGROUND AND OBJECTIVE

Idiopathic pulmonary fibrosis is a chronic progressive disease associated with substantial morbidity and mortality despite advances in medical therapy. Increasing evidence suggests that peroxisome proliferator-activated receptors (PPARs) play important roles in the fibrosis-related diseases and their agonists may become effective therapeutic targets. Pemafibrate is a selective PPARα agonist, but the efficacy against pulmonary fibrosis and mechanisms involved have not been systematically evaluated. Thus, the aims of this study were to explore the role of PPARα in the pulmonary fibrosis and to assess the effect of pemafibrate in vivo and in vitro.

METHODS

The effects of pemafibrate were evaluated in bleomycin-challenged murine pulmonary fibrosis model and transforming growth factor-beta 1 (TGF-β1) stimulated lung fibroblasts.

RESULTS

Bleomycin instillation induced body weight loss, declined lung function, pulmonary fibrosis, and extensive collagen deposition in the mice, accompanied with decreased pulmonary expression of PPARα, all of which were partially improved by pemafibrate at a dose of 2 mg/kg. Besides, pemafibrate effectively inhibits TGF-β1-induced myofibroblast differentiation and extracellular matrix (ECM) production in vivo and in vitro. Furthermore, we showed that pemafibrate not only inhibited pulmonary expression of NLRP3 and cleaved caspase-1 in bleomycin-inhaled mice, but also repressed activation of NLRP3/caspase-1 axis in TGF-β1 stimulated lung fibroblasts.

CONCLUSION

Our data suggest that pemafibrate exerts a marked protection against from the development of pulmonary fibrosis, which could constitute a novel candidate for the treatment for pulmonary fibrosis.

Extracellular Lipids in the Lung and Their Role in Pulmonary Fibrosis

Lipids are major actors and regulators of physiological processes within the lung. Initial research has described their critical role in tissue homeostasis and in orchestrating cellular communication to allow respiration. Over the past decades, a growing body of research has also emphasized how lipids and their metabolism may be altered, contributing to the development and progression of chronic lung diseases such as pulmonary fibrosis. In this review, we first describe the current working model of the mechanisms of lung fibrogenesis before introducing lipids and their cellular metabolism. We then summarize the evidence of altered lipid homeostasis during pulmonary fibrosis, focusing on their extracellular forms. Finally, we highlight how lipid targeting may open avenues to develop therapeutic options for patients with lung fibrosis.

Label-free Raman spectroscopy characterizes signatures of inflammation and fibrosis in the silicosis

Silicosis is an occupational disease that seriously damages the life and health of miners. Herein, we constructed a mouse model of silicosis and used label-free confocal Raman spectroscopy to analyze the biomolecular variations in lung fibrous nodules and inflammatory sites. The mice were exposed to silica particles for 1 month (SIL-1M group), 3 months (SIL-3M group), or no exposure (control tissues, NS). Raman spectra obtained from treated and untreated lung tissue were subjected to chemometric analysis to quantify biochemical composition differences in the silicosis. Simultaneously, immunohistochemistry and collagen staining were used to evaluate inflammation, fibrosis, and apoptosis. As a result, the SIL-1M and SIL-3M groups showed significant differences in cholesterol, lipids, amino acids, nucleic acids, and cytochrome C, and the collagen peaks at 1248 cm^-1 and 1448 cm^-1 were significantly higher than in the NS group. Notably, glycogen and phospholipid may be an inflammatory indicator consistent with NF-κB expression. In addition, significant differences in collagen and cytochrome C content in silicosis lung tissue were found using Raman spectroscopy and were verified by Masson's staining and Bax/Bcl-2 expression ratio. In summary, our findings provide a label-free technique to understand the biochemical changes in lung inflammatory and fibrosis microenvironment after exposure to silica particles and provide a valuable reference for studying the mechanism of silicosis.

Altered lipidomic profiles in lung and serum of rat after sub-chronic exposure to ozone

Ozone (O) exposure not only causes lung injury and lung inflammation but also changes blood composition. Previous studies have mainly focused on inflammatory processes and metabolic diseases caused by acute or chronic ozone exposure. However, the effect of ozone on lipid expression profiles remains unclear. This study aimed to investigate the lipidomic changes in lung tissue and serum of rats after ozone exposure for three months and explore the lipid metabolic pathway involved in an ozone-induced injury. Based on the non-targeted lipidomic analysis platform of the UPLC Orbitrap mass spectrometry system, we found that sub-chronic exposure to ozone significantly changed the characteristics of lipid metabolism in lungs and serum of rats. First, the variation in sphingomyelin (SM) and triglyceride (TG) levels in the lung and serum after O₃ exposure are shown. SM decreased in both tissues, while TG decreased in the lungs and increased in the serum. Further, the effect of ozone on glycerophospholipids in the lung and serum was completely different. Phosphatidylethanolamine (PE), phosphatidylserine (PS), and phosphatidylinositol (PI) were the major glycerophospholipids whose levels were altered in the lung, while phosphatidylglycerol (PG), phosphatidic acid (PA), and phosphatidylcholine (PC) levels changed dramatically in the serum. Third, after O₃ exposure, the level of monogalactosyldiacylglycerol (MGDG), mainly MGDG (43, 11), a saccharolipid, declined significantly and uniquely in the serum. These results suggested that sub-chronic O₃ exposure may play a role in the development of several diseases through perturbation of lipidomic profiles in the lungs and blood. In addition, changes in the lipids of the lung and blood may induce or exacerbate respiratory diseases.

Liu Shen Capsule Alters Airway Microbiota Composition and Metabolite Profiles in Healthy Humans

Alteration in airway microbiota composition and perturbations in microbe-metabolites interactions have been proposed as markers of many diseases. Liu Shen (LS) capsule, a traditional Chinese medicine, was proved as favorable in treating respiratory diseases. However, the effects of the LS capsule in terms of regulating human microorganisms and metabolite profiles are not well known. This study aimed to define and compare the respiratory microbiota composition and circulating and fecal metabolite profiles before and after LS capsule administration. A total of 30 healthy volunteers were recruited. The pharyngeal swab samples were collected for 16S rRNA gene sequencing. The serum and fecal samples were collected to analyze the non-targeted ultra-performance liquid chromatography–tandem mass spectrometry metabolomics. The airway microbial compositions were profoundly altered after LS capsule administration, as evidenced by increased microbial diversity and altered microbial taxa distribution. The increasing abundance of bacterial Bifidobacteria, and Lactobacillus characterized the after-administration groups, and the increasing of abundance bacterial Proteobacteria, Veillonella, Prevotella, Neisseria, and Actinomyces characterized the before-administration groups. Significant discriminations were observed in both serum and fecal metabolic profiles between the before- and after-administration groups. A total number of 134 and 71 significant HMDB taxonomic metabolites including glycerophospholipids, fatty acyls, and prenol lipids in the serum and fecal samples were identified respectively between the before- and after-administration groups. The integrated analysis showed that some altered airway microbiota phylum, such as Bacteroidetes and Proteobacteria, significantly correlated with metabolites in serum and fecal. Hence, our study reported the alternations in the composition and functions of the airway microbial community and the changes in circulating and fecal metabolite profiles after LS capsule administration in healthy humans, thus providing a novel insight into the mechanisms underlying the role of LS capsule treating and preventing related diseases.

Lipid Alterations in Systemic Sclerosis

Background: Systemic sclerosis (SSc) is an autoimmune disease with an elusive etiology and poor prognosis. Due to its diverse clinical presentation, a personalized approach is obligatory and needs to be based on a comprehensive biomarker panel. Therefore, particular metabolomic studies are necessary. Lipidomics addressed these issues and found disturbances in several crucial metabolic pathways.

Aim of Review: The review aims to briefly summarize current knowledge related to lipid alterations in systemic sclerosis, highlight its importance, and encourage further research in this field.

Key Scientific Concepts of Review: In this review, we summarized the studies on the lipidomic pattern, fatty acids, lipoproteins, cholesterol, eicosanoids, prostaglandins, leukotrienes, lysophospholipids, and sphingolipids in systemic sclerosis. Researchers demonstrated several alternate aspects of lipid metabolism. As we aimed to present our findings in a comprehensive view, we decided to divide our findings into three major groups: “serum lipoproteins,” “fatty acids and derivatives,” and “cellular membrane components,” as we do believe they play a prominent role in SSc pathology.

NMR metabolomic and microarray-based transcriptomic data integration identifies unique molecular signatures of hypersensitivity pneumonitis

Hypersensitivity pneumonitis (HP) is an immune-mediated granulomatous interstitial lung disease (ILD) that results from repeated inhalation of certain antigens. Despite major advances in research, pathophysiology of the disease remains poorly understood. The present study combines metabolomic and transcriptomic data to determine alterations in HP subjects as compared with healthy controls. Metabolic signatures were identified in serum, exhaled breath condensate (EBC) and bronchoalveolar lavage fluid (BALF) of HP patients using proton nuclear magnetic resonance (NMR) metabolomics. The expression of three metabolites, i.e., lactate, pyruvate, and proline, was found to be significantly altered in all three biofluids. The potential of differential diagnosis based on these three metabolites was investigated by including a group of patients with sarcoidosis, which is another type of granulomatous ILD. In addition, differentially expressed transcriptomic fingerprints in blood samples were identified by analyzing a Gene Expression Omnibus (GEO) database. The transcriptomics analysis of these microarray-based data revealed 59 genes to be significantly dysregulated in patients with HP. Over representation analysis of the metabolites and genes of interest was performed using IMPaLA (Integrated Molecular Pathway Level Analysis) version 12. Integrated analysis of serum metabolite signatures and blood gene expression suggests dysregulation of PI3K-AKT signaling and TCA cycle pathways in these patients. This preliminary study is a step towards better understanding of the pathogenesis of HP by identification of differentially expressed metabolites and transcriptomic fingerprints. These molecular signatures may be explored as diagnostic markers for differentiating HP from other lung diseases.

Human disease biomarker panels through systems biology

As more uses for biomarkers are sought after for an increasing number of disease targets, single-target biomarkers are slowly giving way for biomarker panels. These panels incorporate various sources of biomolecular and clinical data to guarantee a higher robustness and power of separation for a clinical test. Multifactorial diseases such as psychiatric disorders show great potential for clinical use, assisting medical professionals during the analysis of risk and predisposition, disease diagnosis and prognosis, and treatment applicability and efficacy. More specific tests are also being developed to assist in ruling out, distinguishing between, and confirming suspicions of multifactorial diseases, as well as to predict which therapy option may be the best option for a given patient's biochemical profile. As more complex datasets are entering the field, involving multi-omic approaches, systems biology has stepped in to facilitate the discovery and validation steps during biomarker panel generation. Filtering biomolecules and clinical data, pre-validating and cross-validating potential biomarkers, generating final biomarker panels, and testing the robustness and applicability of those panels are all beginning to rely on machine learning and systems biology and research in this area will only benefit from advances in these approaches.

Efficacy and Safety of Dahuang Zhechong Pill in Silicosis: A Randomized Controlled Trial

Background

There is no effective therapy for silicosis, and Dahuang Zhechong pill (DHZCP), an ancient Chinese medicine prescription, may have a therapeutic effect on silicosis. This study aims to verify the efficacy and safety of DHZCP in silicosis.

Methods

This is a randomized controlled clinical trial done at Panzhihua Second People's Hospital (Panzhihua City, Sichuan Province, China). Participants diagnosed with silicosis were recruited and randomized to the conventional treatment group (CG) or DHZCP combined with the conventional treatment group (DG). Forced vital capacity % predicted (FVC%), diffusing capacity of the lung for carbon monoxide % predicted (DLCO%), six-minute walk distance (6MWD), peripheral oxygen (SpO₂), King's Brief Interstitial Lung Disease Questionnaire (K-BILD), and safety outcomes were measured at baseline and 9 weeks.

Results

Fifty-six participants (28 in each group) completed the study, and 53 of them (26 in DG and 27 in CG) completed pulmonary function. At 9 weeks, compared with no DHZCP, DHZCP treatment was associated with significant improvements in FVC% (mean ± SD, 95%CI) (8.2 ± 3.9, 0.3 to 16.0), DLCO% (8.6 ± 3.5, 1.5 to 15.7), SpO₂ (3.8 ± 0.7, 2.3 to 5.2), and K-BILD total score (6.0 ± 2.3, 1.4 to 10.7). And, there were no statistical differences of safety outcomes between the two groups. Eight patients accepting DHZCP developed mild diarrhea during the first week, which subsequently resolved on its own.

Conclusion

DHZCP could improve the pulmonary function, the quality of life, and the exercise capacity of silicosis patients.

Plasma profiling reveals a blood-based metabolic fingerprint of obstructive sleep apnea

INTRODUCTION

Obstructive sleep apnea (OSA) is a chronic, heterogeneous and multicomponent disorder with associated cardiovascular and metabolic alterations. Despite being the most common sleep-disordered breathing, it remains a significantly undiagnosed condition.

OBJECTIVE

We examined the plasma metabolome and lipidome of patients with suspected OSA, aiming to identify potential diagnosis biomarkers and to provide insights into the pathophysiological mechanisms underlying the disease. Additionally, we evaluated the impact of continuous positive airway pressure (CPAP) treatment on the circulating metabolomic and lipidomic profile.

MATERIAL AND METHODS

Observational-prospective-longitudinal study including 206 consecutive subjects referred to the sleep unit. OSA was defined as an apnea-hypopnoea index ≥ 15 events/h after polysomnography (PSG). Patients treated with CPAP were followed-up for 6 months. Untargeted plasma metabolomic and lipidomic profiling was performed using liquid chromatography coulpled to massspectrometry.

RESULTS

A plasma profile composed of 33 metabolites (mainly glycerophospholipids and bile acids) was identified in OSA vs. non-OSA patients. This profile correlated with specific PSG measures of OSA severity related to sleep fragmentation and hypoxemia. Machine learning analyses disclosed a 4-metabolites-signature that provided an accuracy (95% CI) of 0.98 (0.95-0.99) for OSA detection. CPAP treatment was associated with changes in 5 plasma metabolites previously altered by OSA.

CONCLUSIONS

This analysis of the circulating metabolome and lipidome reveals a molecular fingerprint of OSA, which was modulated after effective CPAP treatment. Our results suggest blood-based biomarker candidates with potential application in the personalized management of OSA and suggest the activation of adaptive mechanisms in response to OSA-derived hypoxia.

Metabolomic Identification of Alpha-Ketoglutaric Acid Elevation in Pediatric Chronic Graft-versus-Host Disease

Chronic graft versus host disease (cGvHD) is the most common cause for non-relapse mortality post allogenic hematopoietic stem cell transplant (HSCT). However, there are no well-defined biomarkers for cGvHD or late acute GvHD (aGvHD). This study is a longitudinal evaluation of metabolomic patterns of cGvHD and late aGvHD in pediatric HSCT recipients. A quantitative analysis of plasma metabolites was performed on 222 evaluable pediatric subjects from the ABLE/PBMTC1202 study. We performed a risk-assignment analysis at day+100 on subjects who later developed either cGvHD or late aGvHD after day 114 to non-cGvHD controls. A second analysis at diagnosis used fixed and mixed multiple regression to compare cGvHD at onset to time matched non-cGvHD controls. A metabolomic biomarker was considered biologically relevant only if it met all three selection criteria: a) p value ≤0.05, b) effect ratio of ≥1.3 or ≤0.75, and c) receiver operator characteristic AUC ≥0.60. We found a consistent elevation in plasma alpha-ketoglutaric acid before (Day + 100) and at the onset of cGvHD, not impacted by cGvHD severity, pubertal status, or previous aGvHD. In addition, late aGvHD had a unique metabolomic pattern at day+100 compared to cGvHD. Additional metabolomic correlation patterns were seen with the clinical presentation of pulmonary, de novo, and progressive cGvHD. Alpha-ketoglutaric acid emerged as the single most significant metabolite associated with cGvHD, both in the day +100 risk-assignment and later diagnostic onset analysis. These distinctive metabolic patterns may lead to improved subclassification of cGvHD. Future validation of these exploratory results are needed.

Pharmaceutical targeting of succinate dehydrogenase in fibroblasts controls bleomycin-induced lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is characterized by excessive deposition of extracellular matrix in the lung with fibroblast-to-myofibroblast transition, leading to chronically compromising lung function and death. However, very little is known about the metabolic alterations of fibroblasts in IPF, and there is still a lack of pharmaceutical agents to target the metabolic dysregulation. Here we show a glycolysis upregulation and fatty acid oxidation (FAO) downregulation in fibroblasts from fibrotic lung, and perturbation of glycolysis and FAO affects fibroblasts transdifferentiation. In addition, there is a significant accumulation of succinate both in fibrotic lung tissues and myofibroblasts, where succinate dehydrogenase (SDH) operates in reverse by reducing fumarate to succinate. Then succinate contributes to glycolysis upregulation and FAO downregulation by stabilizing HIF-1α, which promotes the development of lung fibrosis. In addition, we identify a near-infrared small molecule dye, IR-780, as a targeting agent which stimulates mild inhibition of succinate dehydrogenase subunit A (SDHA) in fibroblasts, and which inhibits TGF-β1 induced SDH and succinate elevation, then to prevent fibrosis formation and respiratory dysfunction. Further, enhanced cell retention of IR-780 is shown to promote severe inhibition of SDHA in myofibroblasts, which may contribute to excessive ROS generation and selectively induces myofibroblasts to apoptosis, and then therapeutically improves established lung fibrosis in vivo. These findings indicate that targeting metabolic dysregulation has significant implications for therapies aimed at lung fibrosis and succinate dehydrogenase is an exciting new therapeutic target to treat IPF.

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Glycolysis upregulation and fatty acid oxidation (FAO) downregulation in fibroblasts lead to lung fibrosis.

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Succinate contributes to metabolic dysregulation of fibroblasts by stabilizing HIF-1α.

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Succinate dehydrogenase is an exciting new therapeutic target to treat IPF.

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IR-780 can be a promising agent to control lung fibrosis by targeting succinate dehydrogenase.

Role and mechanisms of autophagy in lung metabolism and repair

Mammalian lungs are metabolically active organs that frequently encounter environmental insults. Stress responses elicit protective autophagy in epithelial barrier cells and the supportive niche. Autophagy promotes the recycling of damaged intracellular organelles, denatured proteins, and other biological macromolecules for reuse as components required for lung cell survival. Autophagy, usually induced by metabolic defects, regulates cellular metabolism. Autophagy is a major adaptive response that protects cells and organisms from injury. Endogenous region-specific stem/progenitor cell populations are found in lung tissue, which are responsible for epithelial repair after lung damage. Additionally, glucose and fatty acid metabolism is altered in lung stem/progenitor cells in response to injury-related lung fibrosis. Autophagy deregulation has been observed to be involved in the development and progression of other respiratory diseases. This review explores the role and mechanisms of autophagy in regulating lung metabolism and epithelial repair.

There is detectable variation in the lipidomic profile between stable and progressive patients with idiopathic pulmonary fibrosis (IPF)

Background

Idiopathic pulmonary fibrosis (IPF) is a chronic interstitial lung disease characterized by fibrosis and progressive loss of lung function. The pathophysiological pathways involved in IPF are not well understood. Abnormal lipid metabolism has been described in various other chronic lung diseases including asthma and chronic obstructive pulmonary disease (COPD). However, its potential role in IPF pathogenesis remains unclear.

Methods

In this study, we used ultra-performance liquid chromatography-quadrupole time-of-flight mass spectrometry (UPLC-QTOF-MS) to characterize lipid changes in plasma derived from IPF patients with stable and progressive disease. We further applied a data-independent acquisition (DIA) technique called SONAR, to improve the specificity of lipid identification.

Results

Statistical modelling showed variable discrimination between the stable and progressive subjects, revealing differences in the detection of triglycerides (TG) and phosphatidylcholines (PC) between progressors and stable IPF groups, which was further confirmed by mass spectrometry imaging (MSI) in IPF tissue.

Conclusion

This is the first study to characterise lipid metabolism between stable and progressive IPF, with results suggesting disparities in the circulating lipidome with disease progression.

Distinct metabolic features in the plasma of patients with silicosis and dust-exposed workers in China: a case-control study

BACKGROUND

Silicosis is a progressive pneumoconiosis characterized by interstitial fibrosis following exposure to silica dust. The role of metabolic dysregulation in the pathogenesis of silicosis has not been investigated in detail. This study aimed to identify different metabolic features in the plasma of patients with silicosis and dust-exposed workers without silicosis in metabolomics studies.

METHODS

Patients with silicosis, dust-exposed workers (DEWs) without silicosis and age-matched healthy controls were recruited in a case-control study. The metabolomics analyses by ultra-high performance liquid chromatography-mass spectrometry were conducted. Distinct metabolic features (DMFs) were identified in the pilot study and were validated in the validation study. The enriched signalling pathways of these DMFs were determined. The ability of DMFs to discriminate among the groups was analysed through receiver operating characteristic (ROC) curves. The correlations between DMFs and clinical features were also explored.

RESULTS

Twenty-nine DMFs and 9 DMFs were detected and had the same trend in the pilot study and the validation study in the plasma of the DEW and silicosis groups, respectively. Sphingolipid metabolism was the major metabolic pathway in the DEWs, and arginine and proline metabolism was associated with silicosis. Twenty DMFs in the DEWs and 3 DMFs in the patients with silicosis showed a discriminatory ability with ROC curve analysis. The abundance of kynurenine was higher in Stage III silicosis than in Stage I or Stage II silicosis. L-arginine and kynurenine were both negatively correlated with the percentage of forced vital capacity predicted in silicosis.

CONCLUSIONS

Distinct metabolic features in the plasma of DEWs and the patients with silicosis were found to be different. Sphingolipid metabolism and arginine and proline metabolism were identified as the major metabolic pathway in the DEW and silicosis groups, respectively. L-arginine and kynurenine were correlated with the severity of silicosis.

The effects of exercise training on lipid profile in patients with sarcoidosis

This study aimed to determine the use of lipid profiling to assess the effects of moderate intensity exercise training (ET) on patients with sarcoidosis. Fourteen patients with sarcoidosis (mean age, 46.0 ± 9.6 years) were examined before and after 3-week of ET programme in hospital settings. Symptoms (fatigue: FAS, dyspnoea: MRC), lung function tests and physical function tests (6 MWT, muscle force) were measured before and after ET. Proton nuclear magnetic resonance (NMR) spectroscopy combined with orthogonal partial least squares-discriminant analysis (OPLS-DA) was used to determine lipid profile before and after ET. Twenty-five NMR signals from lipid compounds were selected for further analysis as well as serum lipid and inflammatory markers. Three weeks of ET results in improvement of symptoms (FAS: 27.5 vs. 21.0; p < 0.001, MRC: 0.86 vs. 0.14; p = 0.002) and physical function (6MWT: 508.43 vs. 547.29; p = 0.039). OPLS-DA analysis of the lipid profiles of patients with sarcoidosis revealed differences among the samples before and after ET, including decreases in fatty acids (p < 0.017), triglycerides (p < 0.022) and total cholesterol (p < 0.020). Other changes included shifts in fatty acids oxidation products and triacylglycerol esters. A short-time, in-hospital exercise training benefits patients with sarcoidosis by enhancing their physical function. Additionally, positive effect on lipid profile was observed also in this study. It is suggested that lipid profiling could become a new prognostic method to assess effects of pulmonary rehabilitation in patients with sarcoidosis.

Metabolic requirements of pulmonary fibrosis: role of fibroblast metabolism

Fibrosis is a pathologic condition characterized by excessive deposition of extracellular matrix and chronic scaring that can affect every organ system. Organ fibrosis is associated with significant morbidity and mortality, contributing to as many as 45% of all deaths in the developed world. In the lung, many chronic lung diseases may lead to fibrosis, the most devastating being idiopathic pulmonary fibrosis (IPF), which affects approximately 3 million people worldwide and has a median survival of 3.8 years. Currently approved therapies for IPF do not significantly extend lifespan, and thus, there is pressing need for novel therapeutic strategies to treat IPF and other fibrotic diseases. At the heart of pulmonary fibrosis are myofibroblasts, contractile cells with characteristics of both fibroblasts and smooth muscle cells, which are the primary cell type responsible for matrix deposition in fibrotic diseases. Much work has centered around targeting the extracellular growth factors and intracellular signaling regulators of myofibroblast differentiation. Recently, metabolic changes associated with myofibroblast differentiation have come to the fore as targetable mechanisms required for myofibroblast function. In this review, we will discuss the metabolic changes associated with myofibroblast differentiation, as well as the mechanisms by which these changes promote myofibroblast function. We will then discuss the potential for this new knowledge to lead to the development of novel therapies for IPF and other fibrotic diseases.

Stearic acid attenuates profibrotic signalling in idiopathic pulmonary fibrosis

BACKGROUND AND OBJECTIVE

Lipid metabolism dysregulation has been implicated in the pathogenesis of IPF; however, the roles of most lipid metabolites in lung fibrosis remain unexplored. Therefore, we aimed to identify changes in lipid metabolites in the lung tissues of IPF patients and determine their roles in pulmonary fibrosis.

METHODS

Free fatty acids in the lung tissues of IPF patients and controls were quantified using a metabolomic approach. The roles of free fatty acids in fibroblasts or epithelial cells treated with TGF-β1 were evaluated using fibrotic markers. The antifibrotic role of stearic acid was also assessed in a bleomycin-induced lung fibrosis mouse model. Protein levels in cell lysates or tissues were measured by western blotting.

RESULTS

The levels of stearic acid were lower in IPF lung tissues than in control lung tissues. Stearic acid significantly reduced TGF-β1-induced α-SMA and collagen type 1 expression in MRC-5 cells. Furthermore, stearic acid decreased the levels of p-Smad2/3 and ROS in MRC-5 cells treated with TGF-β1 and disrupted TGF-β1-induced EMT in Beas-2B cells. Stearic acid reduced the levels of bleomycin-induced hydroxyproline in a mouse model.

CONCLUSION

Changes in the free fatty acid profile, including low levels of stearic acid, were observed in IPF patients. Stearic acid may exert antifibrotic activity by regulating profibrotic signalling.

Metabolomic analysis of fibrotic mice combined with public RNA-Seq human lung data reveal potential diagnostic biomarker candidates for lung fibrosis

Idiopathic pulmonary fibrosis (IPF) is a severe lung disease with poor survival that warrants early and precise diagnosis for timely therapeutic intervention. Despite accumulating genomic, transcriptomic, proteomic, and lipidomic data on IPF, evidence from water‐soluble metabolomics is limited. To identify biomarkers for IPF from water‐soluble metabolomic data, we measured the levels of various metabolites in bronchoalveolar lavage fluid (BALF) and serum samples from a bleomycin‐induced murine pulmonary fibrotic model using gas chromatography/mass spectrometry. Thirty‐two of 73 BALF metabolites and 29 of 74 serum metabolites were annotated. We observed that the levels of proline and methionine were higher in BALF but lower in serum than those in the control. Furthermore, analysis of public RNA‐Seq data from the lungs of patients with IPF revealed that proline‐ and methionine‐related genes were significantly upregulated compared to those in the lungs of healthy controls. These results suggest that proline and methionine may be potential biomarkers for IPF and may help to deepen our understanding of the pathophysiology of the disease. Based on our results, we propose a model capable of recapitulating the proline and methionine metabolism of fibrotic lungs, thereby providing better means for studying the disease and developing novel therapeutic strategies for IPF.

Insights into the Role of Bioactive Food Ingredients and the Microbiome in Idiopathic Pulmonary Fibrosis

Idiopathic pulmonary fibrosis (IPF) is a chronic disease mainly associated with aging and, to date, its causes are still largely unknown. It has been shown that dietary habits can accelerate or delay the occurrence of aging-related diseases; however, their potential role in IPF development has been underestimated so far. The present review summarizes the evidence regarding the relationship between diet and IPF in humans, and in animal models of pulmonary fibrosis, in which we discuss the bioactivity of specific dietary food ingredients, including fatty acids, peptides, amino acids, carbohydrates, vitamins, minerals and phytochemicals. Interestingly, many animal studies reveal preventive and therapeutic effects of particular compounds. Furthermore, it has been recently suggested that the lung and gut microbiota could be involved in IPF, a relationship which may be linked to changes in immunological and inflammatory factors. Thus, all the evidence so far puts forward the idea that the gut-lung axis could be modulated by dietary factors, which in turn have an influence on IPF development. Overall, the data reviewed here support the notion of identifying food ingredients with potential benefits in IPF, with the ultimate aim of designing nutritional approaches as an adjuvant therapeutic strategy.