Protective Effects of Functional Amino Acids on Apoptosis, Inflammatory Response, and Pulmonary Fibrosis in Lipopolysaccharide-Challenged Mice

Silica aggravates pulmonary fibrosis through disrupting lung microbiota and amino acid metabolites

Silicosis, recognized as a severe global public health issue, is an irreversible pulmonary fibrosis caused by the long-term inhalation of silica particles. Given the intricate pathogenesis of silicosis, there is no effective intervention measure, which poses a severe threat to public health. Our previous study reported that dysbiosis of lung microbiota is associated with the development of pulmonary fibrosis, potentially involving the lipopolysaccharides/toll-like receptor 4 pathway. Similarly, the process of pulmonary fibrosis is accompanied by alterations in metabolic pathways. This study employed a combined approach of 16S rDNA sequencing and metabolomic analysis to investigate further the role of lung microbiota in silicosis delving deeper into the potential pathogenesis of silicosis. Silica exposure can lead to dysbiosis of the lung microbiota and the occurrence of pulmonary fibrosis, which was alleviated by a combination antibiotic intervention. Additionally, significant metabolic disturbances were found in silicosis, involving 85 differential metabolites among the three groups, which are mainly focused on amino acid metabolic pathways. The changed lung metabolites showed a substantial correlation with lung microbiota. The relative abundance of Pseudomonas negatively correlated with L-Aspartic acid, L-Glutamic acid, and L-Threonine levels. These results indicate that dysbiosis in pulmonary microbiota exacerbates silica-induced fibrosis through impacts on amino acid metabolism, providing new insights into the potential mechanisms and interventions of silicosis.

Naringin dihydrochalcone alleviates sepsis-induced acute lung injury via improving gut microbial homeostasis and activating GPR18 receptor

Acute lung injury (ALI) is a life-threatening disease characterized by severe lung inflammation and intestinal microbiota disorder. The GPR18 receptor has been demonstrated to be a potential therapeutic target against ALI. Extracting Naringin dihydrochalcone (NDC) from the life-sustaining orange peel is known for its diverse anti-inflammatory properties, yet the specific action target remains uncertain. In the present study, we identified NDC as a potential agonist of the GPR18 receptor using virtual screening and investigated the pharmacological effects of NDC on sepsis-induced acute lung injury in rats and explored underlying mechanisms. In in vivo experiments, CLP-induced ALI model was established by cecum puncture and treated with NDC gavage one hour prior to drug administration, lung histopathology and inflammatory cytokines were evaluated, and feces were subjected to 16s rRNA sequencing and untargeted metabolomics analysis. In in vitro experiments, the anti-inflammatory properties were exerted by evaluating NDC targeting the GPR18 receptor to inhibit lipopolysaccharide (LPS)-induced secretion of TNF-α, IL-6, IL-1β and activation of inflammatory signaling pathways in MH-S cells. Our findings showed that NDC significantly ameliorated lung damage and pro-inflammatory cytokine levels (TNF-α, IL-6, IL-1β) in both cells and lung tissues via inhibiting the activation of STAT3, NF-κB, and NLRP3 inflammatory signaling pathways through GRP18 receptor activation. In addition, NDC can also partly reverse the imbalance of gut microbiota composition caused by CLP via increasing the proportion of Firmicutes/Bacteroidetes and Lactobacillus and decreasing the relative abundance of Proteobacteria. Meanwhile, the fecal metabolites in the NDC treatment group also significantly were changed, including decreased secretion of Phenylalanin, Glycine, and bile secretion, and increased secretion of Lysine. In conclusion, these findings suggest that NDC can alleviate sepsis-induced ALI via improving gut microbial homeostasis and metabolism and mitigate inflammation via activating GPR18 receptor. In conclusion, the results indicate that NDC, derived from the typical orange peel of food, could significantly contribute to development by enhancing intestinal microbial balance and metabolic processes, and reducing inflammation by activating the GPR18 receptor, thus mitigating sepsis-induced ALI and expanding the range of functional foods.

Study on the metabolic effects of hexavalent chromium [Cr (VI)] on rat astrocytes using un-targeted metabolomics

Introduction: Hexavalent chromium [Cr (VI)] has been identified as a human carcinogen and environmental pollutant capable of affecting multiple systems in the human body. However, the specific mechanisms by which Cr (VI) affects the human nervous system remain unclear. Objective: Following confirmation of Cr (VI)'s toxic effects on rat astrocytes, this study explores the metabolites and associated metabolic pathways of rat astrocytes under different doses of Cr (VI) exposure. Methods: Cell viability was assessed using CCK8 assays, intracellular reactive oxygen species (ROS) levels were measured using DCFH-DA fluorescent probes, intracellular 8-hydroxydeoxyguanosine (8-OHdG) content was determined by Elisa, mitochondrial membrane potential was observed using JC-1 probes, and key metabolites were identified through untargeted metabolomics analysis. Results: With increasing Cr (VI) doses, significant decreases in cell viability were observed in the 4, 8, and 16 mg/L dose groups (p < 0.05). Elevated levels of ROS and 8-OHdG, increased caspase-3 activity, and significant reductions in mitochondrial membrane potential were observed in the 2 and 4 mg/L dose groups (p < 0.05). Untargeted metabolomics analysis revealed Cr (VI)'s impact on key metabolites such as sphingosine and methionine. Enrichment analysis of KEGG pathways highlighted the critical roles of sphingolipid metabolism and the methionine-cysteine cycle in the effects of Cr (VI) on rat astrocytes. Conclusion: Our study underscores the potential neuro-health risks associated with environmental and occupational exposure to Cr (VI) and provides new perspectives and directions for investigating neurotoxic mechanisms.

Strictosamide alleviates acute lung injury via regulating T helper 17 cells, regulatory T cells, and gut microbiota

BACKGROUND

Nauclea officinalis (Pierre ex Pit.) Merr. & Chun (Rubiaceae) is widely used to treat respiratory diseases in China. Strictosamide is its main active component and has significant anti-inflammatory activity. However, the effects and molecular mechanisms of strictosamide in the treatment of acute lung injury (ALI) remain largely unknown.

PURPOSE

This study aimed to examine the regulatory effects of strictosamide on T helper 17 cells (Th17 cells)/Regulatory T cells (Treg cells) and gut microbiota in ALI-affected mice.

MATERIALS AND METHODS

The ALI model was induced using lipopolysaccharide (LPS) intraperitoneal injection. Hematoxylin-eosin (H&E) staining, the number of inflammatory cells in broncho-alveolar lavage fluid (BALF), the Wet/Dry (W/D) ratio, and myeloperoxidase (MPO) activity were utilized as evaluation indices for the therapeutic efficacy of strictosamide on ALI. Flow cytometry (FCM), enzyme-linked immune sorbent assay (ELISA), quantitative reverse transcription polymerase chain reaction (qRT-PCR), and western blotting were used to determine the regulation of strictosamide on the Th17/Treg cells and the STAT3/STAT5 signaling pathway. The analysis of gut microbiota was conducted using 16S rDNA sequencing. The verification of the relationship between the gut microbiome and immune function was conducted using Spearman analysis.

RESULTS

Strictosamide attenuated inflammation on ALI induced by LPS, which reduced the levels of Th17-related factors interleukin (IL)-6 and IL-17 and increased Treg-related factors IL-10 and transforming growth factor (TGF)-β. In the spleens and whole blood, strictosamide reduced the proportion of Th17 cells and increased the proportion of Treg cells. Furthermore, strictosamide increased Forkhead/winged helix transcription factor 3 (Foxp3) and p-STAT5 protein expression while inhibiting Retinoid-related orphan nuclear receptors-γt (RORγt) and p-STAT3 expression. Moreover, strictosamide reshaped the diversity and structure of the gut microbiota, and influence the associations between immune parameters and gut microbiota in ALI mice.

CONCLUSIONS

In summary, the results of the current investigation showed that strictosamide has a therapeutic impact on LPS-induced ALI. The mechanism of action of this effect may be associated with the modulation of Th17 and Treg cells differentiation via the SATA signaling pathway, as well as the impact of the gut microbiota.

Arginine alleviates Clostridium perfringens α toxin-induced intestinal injury in vivo and in vitro via the SLC38A9/mTORC1 pathway

Introduction

Clostridium perfringens α toxin is a main virulence factor responsible for gut damage in animals. Arginine is a functional amino acid exhibiting significant immunoregulatory activities. However, the effects and immunoregulatory mechanisms of arginine supplementation on α toxin-induced intestinal injury remain unclear.

Methods

In vivo, 256 male Arbor Acres chickens were randomly assigned to a 2×2 factorial arrangement, involving diet treatments (with or without 0.3% arginine supplementation) and immunological stress (with or without α toxin challenge). In vitro, IEC-6 cells were treated with or without arginine in the presence or absence of α toxin. Moreover, IEC-6 cells were transfected with siRNA targeting mTOR and SLC38A9 to explore the underlying mechanisms.

Results and discussion

The results showed that in vivo, arginine supplementation significantly alleviated the α toxin-induced growth performance impairment, decreases in serum immunoglobulin (Ig)A and IgG levels, and intestinal morphology damage. Arginine supplementation also significantly reduced the α toxin-induced increase in jejunal proinflammatory cytokines interleukin (IL)-1β, IL-6 and IL-17 mRNA expression. Clostridium perfringens α toxin significantly decreased jejunal mechanistic target of rapamycin (mTOR) and solute carrier family 38 member 9 (SLC38A9) mRNA expression, while arginine supplementation significantly increased mTOR and SLC38A9 mRNA expression. In vitro, arginine pretreatment mitigated the α toxin-induced decrease in cell viability and the increase in cytotoxicity and apoptosis. Arginine pretreatment also alleviated the α toxin-induced upregulation of mRNA expression of inflammation-related cytokines IL-6, C-X-C motif chemokine ligand (CXCL)10, CXCL11 and transforming growth factor-β (TGF-β), as well as apoptosis-related genes B-cell lymphoma-2 associated X protein (Bax), B-cell lymphoma-2 (Bcl-2), B-cell lymphoma-extra large (Bcl-XL) and cysteinyl aspartate specific proteinase 3 (Caspase-3) and the ratio of Bax to Bcl-2. Arginine pretreatment significantly increased the α toxin-induced decrease in mTOR, SLC38A9, eukaryotic translation initiation factor 4E (eIF4E)-binding protein 1 (4EBP1) and ribosomal protein S6 kinase (S6K) mRNA expression. Knockdown SLC38A9 and mTOR largely abrogated the positive effects of arginine pretreatment on α toxin-induced intracellular changes. Furthermore, SLC38A9 silencing abolished the increased mTOR mRNA expression caused by arginine pretreatment. In conclusion, arginine administration attenuated α toxin-induced intestinal injury in vivo and in vitro, which could be associated with the downregulation of inflammation via regulating SLC38A9/mTORC1 pathway.

Discovery of the toxicity-related quality markers and mechanisms of Zhi-Zi-Hou-Po decoction based on Chinmedomics combined with differentially absorbed components and network pharmacology

ETHNOPHARMACOLOGICAL RELEVANCE

Zhi-Zi-Hou-Po decoction (ZZHPD), as a representative traditional Chinese medicine (TCM) formula for the treatment of depression, has frequently triggered hepatorenal toxicity in recent years. However, its toxic effect, material basis, and underlying mechanisms have not been fully elucidated.

AIM OF THE STUDY

To explore the hepatorenal toxicity-material basis-quality markers (Q-markers) and multiple mechanisms of ZZHPD.

MATERIALS AND METHODS

ZZHPD-induced rat model of toxicity was evaluated by behavioral indicators, biochemical parameters, and histopathological sections. Then, UHPLC-Q-Exactive Orbitrap-MS combined with multivariate data analysis was utilized to identify the endogenous differential metabolites and the prototype components of ZZHPD in the plasma. A comprehensive strategy integrating in-house library, diagnostic ions, Compound Discover software, and network databases was constructed to identify the chemical constituents of ZZHPD. Additionally, the differentially absorbed components of ZZHPD were screened out based on the spectrum-effect relationship (toxic state and normal state), feature extraction of exogenous components, and variable influence on projection (VIP). Further, Chinmedomics and network pharmacology oriented by differentially absorbed components were performed to predict toxicity-related Q-markers and core targets, as well as relevant pathways. Finally, the binding ability between components and targets was predicted using molecular docking, and the mRNA expression of core target genes was determined by real-time qPCR experiment.

RESULTS

ZZHPD exerted significant hepatotoxicity and nephrotoxicity in rats accompanied by body weight loss, abnormal biochemical indicators, and pathologic characteristics with mild inflammation and cell damage. The results of plasma metabolomics indicated that 22 differential metabolites interfered by ZZHPD mainly involved in primary bile acid biosynthesis, arginine and proline metabolism, phenylalanine metabolism and biosynthesis, sphingolipid metabolism, pyrimidine and purine metabolism. Firstly, 106 chemical substances of ZZHPD were identified, 44 of them were absorbed into the blood, mainly including 7 iridoid glycosides, 15 flavonoids, 5 lignans, and others. Then, the correlation analysis results suggested that 12 of 19 differentially absorbed constituents were highly correlated with 22 differential metabolites and recognized as potential Q-markers. Finally, 9 toxicity-related Q-markers were predicted and confirmed with better binding ability to 5 core targets (PTGS2, CASP3, TNF, PPARG, HMOX1), including 3 flavonoids (naringin, hesperidin, and neohesperidin), 2 iridoid glycosides (geniposide and genipin-1-β-D-gentiobioside), 2 lignans (honokiol and magnolol), organic acid (chlorogenic acid), and crocin (crocetin). The real-time qPCR results showed that the mRNA levels of CASP3, TNF-α, and PPARG significantly increased in the damaged liver. Combining metabolomics and network pharmacology results, the multiple mechanisms of toxicity might involve in oxidative damage, inflammation, and apoptosis pathways.

CONCLUSION

Taken together, the toxicity-related Q-markers of ZZHPD screened for the first time in this work were reliable, and the holistic intervention for hepatorenal toxicity further revealed the multi-component, multi-target, and multi-pathway features in TCM. The integrated approach provides a novel perspective for the discovery of toxicity/efficacy-related substances and mechanistic studies in TCM.

The identification of key metabolites and mechanisms during isoniazid/rifampicin-induced neurotoxicity and hepatotoxicity in a mouse model by HPLC-TOF/MS-based untargeted urine metabolomics

The co-administration of isoniazid (INH) and rifampicin (RIF) is associated with hepatotoxicity and neurotoxicity. To systematically investigate the mechanisms of hepatotoxicity and neurotoxicity induced by INH/RIF, we used high performance liquid chromatography-time of flight mass spectrometry (HPLC-TOF/MS)-based untargeted metabolomics to analyze urine from a mouse model and screened a range of urinary biomarkers. Mice were orally co-administered with INH (120 mg/kg) and RIF (240 mg/kg) and urine samples were collected on days 0, 7, 14 and 21. Hepatotoxicity and neurotoxicity were assessed by samples of liver, brain and kidney tissue which were harvested for histological analysis. Toxicity analysis revealed that INH/RIF caused hepatotoxicity and neurotoxicity in a time-dependent manner; compared with day 0, the levels of 35, 82 and 86 urinary metabolites were significantly different on days 7, 14 and 21, respectively. Analysis showed that by day 21, exposure to INH+RIF had caused disruption in vitamin B6 metabolism; the biosynthesis of unsaturated fatty acids; tyrosine, taurine, hypotaurine metabolism; the synthesis of ubiquinone and other terpenoid-quinones; and the metabolism of tryptophan, nicotinate and nicotinamide. Nicotinic acid, nicotinuric acid and kynurenic acid were identified as sensitive urinary biomarkers that may be useful for the diagnosis and evaluation of toxicity.

Metabolomic Signatures Associated with Radiation-Induced Lung Injury by Correlating Lung Tissue to Plasma in a Rat Model

The lung has raised significant concerns because of its radiosensitivity. Radiation-induced lung injury (RILI) has a serious impact on the quality of patients' lives and limits the effect of radiotherapy on chest tumors. In clinical practice, effective drug intervention for RILI remains to be fully elucidated. Therefore, an in-depth understanding of the biological characteristics is essential to reveal the mechanisms underlying the complex biological processes and discover novel therapeutic targets in RILI. In this study, Wistar rats received 0, 10, 20 or 35 Gy whole-thorax irradiation (WTI). Lung and plasma samples were collected within 5 days post-irradiation. Then, these samples were processed using liquid chromatography-mass spectrometry (LC-MS). A panel of potential plasma metabolic markers was selected by correlation analysis between the lung tissue and plasma metabolic features, followed by the evaluation of radiation injury levels within 5 days following whole-thorax irradiation (WTI). In addition, the multiple metabolic dysregulations primarily involved amino acids, bile acids and lipid and fatty acid β-oxidation-related metabolites, implying disturbances in the urea cycle, intestinal flora metabolism and mitochondrial dysfunction. In particular, the accumulation of long-chain acylcarnitines (ACs) was observed as early as 2 d post-WTI by dynamic plasma metabolic data analysis. Our findings indicate that plasma metabolic markers have the potential for RILI assessment. These results reveal metabolic characteristics following WTI and provide new insights into therapeutic interventions for RILI.

Diagnostic value of serum neuroactive substances in the acute exacerbation of chronic obstructive pulmonary disease complicated with depression

We aimed to investigate the potential diagnostic value of five serum neuroactive substances in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) complicated with depression. A total of 103 patients with AECOPD were enrolled between August 2020 and August 2021. All patients were assessed using a self-rating depression scale and divided into AECOPD with or without depression groups. Baseline data and serum neuroactive substance levels were compared between the two groups. Logistic regression was used to identify the risk factors. The diagnostic performance of neuroactive substances was evaluated using receiver operating characteristic (ROC) curves. Patients with AECOPD complicated with depression exhibited higher partial pressure of CO2 values and higher chronic obstructive pulmonary disease assessment test (CAT) scores. An elevated proportion of patients with more than two acute exacerbations (AEs) in the previous year was observed in this patient group (all P < 0.001). The CAT score and number of AEs during the previous year were identified as independent risk factors for AECOPD complicated with depression. No significant differences were observed in the levels of aspartic acid and glutamate between the two groups (P > 0.05). Serum γ-aminobutyric acid (GABA) and glycine (Gly) levels were decreased. In contrast, serum nitric oxide (NO) levels were increased in the AECOPD complicated with the depression group (P < 0.05). Serum GABA and Gly levels exhibited a negative correlation, and NO levels positively correlated with the number of AEs in the previous year and the CAT score. The area under the ROC curve values for GABA, Gly, and NO were 0.755, 0.695, and 0.724, respectively. Serum GABA exhibited a sensitivity of 85.1% and a specificity of 58.9%, below the cut-off value of 4855.98 nmol/L. Serum GABA, Gly, and NO may represent potential biomarkers for AECOPD complicated with depression.

Glycine: The Smallest Anti-Inflammatory Micronutrient

Glycine is a non-essential amino acid with many functions and effects. Glycine can bind to specific receptors and transporters that are expressed in many types of cells throughout an organism to exert its effects. There have been many studies focused on the anti-inflammatory effects of glycine, including its abilities to decrease pro-inflammatory cytokines and the concentration of free fatty acids, to improve the insulin response, and to mediate other changes. However, the mechanism through which glycine acts is not clear. In this review, we emphasize that glycine exerts its anti-inflammatory effects throughout the modulation of the expression of nuclear factor kappa B (NF-κB) in many cells. Although glycine is a non-essential amino acid, we highlight how dietary glycine supplementation is important in avoiding the development of chronic inflammation.

Amifostine attenuates bleomycin-induced pulmonary fibrosis in mice through inhibition of the PI3K/Akt/mTOR signaling pathway

Amifostine is a normal cell protection agent, not only used in the adjuvant therapy of lung cancer, ovarian cancer, breast cancer, nasopharyngeal cancer, bone tumor, digestive tract tumor, blood system tumor and other cancers in order to reduce the toxicity of chemotherapy drugs, and recent studies have reported that the drug can also reduce lung tissue damage in patients with pulmonary fibrosis, but its mechanism of action is not yet fully understood. In this study, we explored the potential therapeutic effects and molecular mechanisms of AMI on bleomycin (BLM)-induced pulmonary fibrosis in mice. A mouse model of pulmonary fibrosis was established using BLM. We then assessed histopathological changes, inflammatory factors, oxidative indicators, apoptosis, epithelial-mesenchymal transition, extracellular matrix changes, and levels of phosphatidylinositol 3-kinase (PI3K)/Akt/mammalian target of rapamycin (mTOR) signaling pathway-related proteins in the BLM-treated mice to determine the effect of AMI treatment on these factors. BLM-treated mice had substantial lung inflammation and abnormal extracellular matrix deposition. Overall, treatment with AMI significantly improved BLM-induced lung injury and pulmonary fibrosis. More specifically, AMI alleviated BLM-induced oxidative stress, inflammation, alveolar cell apoptosis, epithelial-mesenchymal transition, and extracellular matrix deposition by regulating the PI3K/Akt/mTOR signaling pathway. This finding that AMI can alleviate pulmonary fibrosis in a mouse model by inhibiting activation of the PI3K/Akt/mTOR signaling pathway lays a foundation for potential future clinical application of this agent in patients with pulmonary fibrosis.

Targeting EFNA1 suppresses tumor progression via the cMYC-modulated cell cycle and autophagy in esophageal squamous cell carcinoma

PURPOSE

Esophageal squamous cell carcinoma (ESCC) remains one of the most common causes of cancer death due to the lack of effective therapeutic options. New targets and the targeted drugs are required to be identified and developed.

METHODS

Highly expressed genes in ESCA were identified using the edgeR package from public datasets. Immunostaining assay verified the high expression level of EFNA1 in ESCC. CCK-8, colony formation and wound healing assays were performed to examine the role of EFNA1 and EPHA2 in ESCC progression. Cell cycle was analyzed by flow cytometry and autophagy activation was determined by autophagolysosome formation using transmission electron microscopy. The small molecule targeting to EFNA1 was identified by molecular docking and the anti-tumor effects were verified by in vitro and in vivo models with radiation treatment.

RESULTS

EFNA1 was highly expressed in esophageal cancer and significantly associated with poor prognosis. Downregulation of EFNA1 remarkably inhibited cell proliferation and migration. Furthermore, decreased EFNA1 significantly suppressed the expression of cMYC along with its representative downstream genes involved in cell cycle, and activated autophagy. Similar effects on ESCC progression were obtained from knockdown of the corresponding receptor, EPHA2. The potential small molecule targeting to EFNA1, salvianolic acid A (SAA), could significantly suppress ESCC progression and increase the sensitivity to radiotherapy.

CONCLUSION

We revealed that EFNA1 facilitated the ESCC progression via the possible mechanism of activating cMYC-modulated cell proliferation and suppressing autophagy, and identified SAA as a potential drug targeting EFNA1, providing new options for the future treatments for ESCC patients.

Analysis of 12 Chemical Compounds And Pattern Recognition of Different Parts of Angelicae Sinensis Radix by Liquid Chromatography-Tandem Mass Spectrometry And Chemometrics Methods

To evaluate the quality and quantify bioactive constituents in different parts of Angelicae Sinensis Radix, an efficient, high-speed, high-sensitivity high-performance liquid chromatography and triple quadrupole mass spectrometry method was used for simultaneous detection of 12 chemical compounds including L-tryptophan, chlorogenic acid, caffeic acid, ferulic acid, isoferulic acid, senkyunolide I, guanosine, proline, L-glutamine, γ-aminobutyric acid, glutamic acid, and arginine in 52 batches of Angelicae Sinensis Radix from Gansu, China. The established methods were validated by good linearity (R2≥0.9921), limits of detection (0.0001-0.0156 μg/mL), limits of quantitation (0.0006-0.0781 μg/mL), stability (RSD≤7.77%), repeatability (RSD≤6.79%), intra- and interday precisions (RSD≤6.00% and RSD≤6.39%, respectively) and recovery (90.90-107.16%). According to the quantitative results, the contents of the hydrophilic compounds were higher in the head, while the medium and weak polar components were mainly concentrated in the tail. Finally, principal component analysis results revealed that Angelicae Sinensis Radix could be divided into different medicinal sites based on polar components such as amino acids, nucleosides. The combination of liquid chromatography-tandem mass spectrometry and principal component analysis is a simple and reliable method for pattern recognition and quality evaluation of Angelicae Sinensis Radix.

Arginine concentration in arterial vs venous blood in a bleomycin-induced lung inflammation model in mice

Pneumonia, always a major malady, became the main public health and economic disaster of historical proportions with the COVID-19 pandemic. This study was based on a premise that pathology of lung metabolism in inflammation may have features invariant to the nature of the underlying cause. Amino acid uptake by the lungs was measured from plasma samples collected pre-terminally from a carotid artery and vena cava in mice with bleomycin-induced lung inflammation (N = 10) and compared to controls treated with saline instillation (N = 6). In the control group, the difference in concentrations between the arterial and venous blood of the 19 amino acids measured reached the level of statistical significance only for arginine (-10.7%, p = 0.0372) and phenylalanine (+5.5%, p = 0.0266). In the bleomycin group, 11 amino acids had significantly lower concentrations in the arterial blood. Arginine concentration was decreased by 21.1% (p<0.0001) and only that of citrulline was significantly increased (by 20.1%, p = 0.0002). Global Arginine Bioavailability Ratio was decreased in arterial blood by 19.5% (p = 0.0305) in the saline group and by 30.4% (p<0.0001) in the bleomycin group. Production of nitric oxide (NO) and citrulline from arginine by the inducible nitric oxide synthase (iNOS) is greatly increased in the immune system's response to lung injury. Deprived of arginine, the endothelial cells downstream may fail to provide enough NO to prevent the activation of thrombocytes. Thrombotic-related vascular dysfunction is a defining characteristic of pneumonia, including COVID-19. This experiment lends further support to arginine replacement as adjuvant therapy in pneumonia.

Integration of metabolomics and proteomics analysis to explore the mechanism of neurotoxicity induced by receipt of isoniazid and rifampicin in mice

Isoniazid (INH) and rifampicin (RIF) are co-administered in tuberculosis treatment but can cause neurotoxicity, and the mechanism is not known. To explore this mechanism, we employed an integrated approach using metabolomics analysis (MA) and proteomics analysis (PA). Male mice were divided into three groups and administered vehicle (control group), or co-administered INH (120 mg/kg) and RIF (240 mg/kg), for 7 or 14 days. Mice brains were collected for mass spectrometry-based PA and MA plus lipidomics analysis. Measurement of brain levels of malondialdehyde and superoxide dismutase revealed time-dependent brain injury after exposure to INH+RIF for 7 and 14 days. Also, 422 proteins, 35 metabolites, and 21 lipids were dysregulated and identified. MA demonstrated "purine metabolism," "phenylalanine, tyrosine and tryptophan biosynthesis," "biosynthesis of unsaturated fatty acids," "phenylalanine metabolism," and "arginine biosynthesis" to be disturbed significantly. PA demonstrated pathways such as "lipids," "amino acids," and "energy metabolism" to be disrupted. Peroxisome proliferator-activated receptor (PPAR) pathways were changed in energy metabolism, which led to the neurotoxicity induced by INH+RIF. Immunohistochemical analyses of PPARs in mice brains verified that PPAR-α and -γ expression was downregulated. PPAR-α and -γ activation might be a key target for alleviating INH+RIF-induced neurotoxicity.

Inhibition of inflammasome activation via sphingolipid pathway in acute lung injury by Huanglian Jiedu decoction: An integrative pharmacology approach

BACKGROUND

Acute lung injury (ALI) is a serious health issue which causes significant morbidity and mortality. Inflammation is an important factor in the pathogenesis of ALI. Even though ALI has been successfully managed using a traditiomal Chinese medicine (TCM), Huanglian Jiedu Decoction (HLD), its mechanism of action remains unknown.

PURPOSE

This study explored the therapeutic potential of HLD in lipopolysaccharide (LPS)-induced ALI rats by utilizing integrative pharmacology.

METHODS

Here, the therapeutic efficacy of HLD was evaluated using lung wet/dry weight ratio (W/D), myeloperoxide (MPO) activity, and levels of tumor necrosis factor (TNF-α), interleukin (IL)-1β and IL-6. Network pharmacology predictd the active components of HLD in ALI. Lung tissues were subjected to perform Hematoxylin-eosin (H&E) staining, metabolomics, and transcriptomics. The acid ceramidase (ASAH1) inhibitor, carmofur, was employedto suppress the sphingolipid signaling pathway.

RESULTS

HLD reduced pulmonary edema and vascular permeability, and suppressed the levels of TNF-α, IL-6, and IL-1β in lung tissue, Bronchoalveolar lavage fluid (BALF), and serum. Network pharmacology combined with transcriptomics and metabolomics showed that sphingolipid signaling was the main regulatory pathway for HLD to ameliorate ALI, as confirmed by immunohistochemical analysis. Then, we reverse verified that the sphingolipid signaling pathway was the main pathway involed in ALI. Finally, berberine, baicalein, obacunone, and geniposide were docked with acid ceramidase to further explore the mechanisms of interaction between the compound and protein.

CONCLUSION

HLD does have a better therapeutic effect on ALI, and its molecular mechanism is better elucidated from the whole, which is to balance lipid metabolism, energy metabolism and amino acid metabolism, and inhibit NLRP3 inflammasome activation by regulating the sphingolipid pathway. Therefore, HLD and its active components can be used to develop new therapies for ALI and provide a new model for exploring complex TCM systems for treating ALI.

Integrated Pharmacology Reveals the Molecular Mechanism of Gegen Qinlian Decoction Against Lipopolysaccharide-induced Acute Lung Injury

ALI is a severe inflammatory disease of the lungs. In previous studies, we found that GQD was effective against ALI, but specific molecular mechanism is still unclear. Therefore, this study was to examine effect of GQD on LPS-induced ALI rats and underlying mechanisms using multi-omics and molecular methods. The results showed that GQD significantly improved lung tissue damage, reduced pulmonary edema, inhibited MPO activity, and improved respiratory function in ALI rat. Additionally, GQD significantly reduced the levels of TNF-α, IL-1β, and IL-6 in serum and BALF. Furthermore, metabolomic analysis showed that GQD reduced pulmonary inflammation by improving metabolic remodeling. Moreover, transcriptomic analysis showed that GQD inhibited the activation of complement pathway and regulated Th17 and Treg cells balance. Additionally, GQD inhibited the expression of C3, C5a, and IL-17, and promoted the expression of TGF-β and CYP1A1 at the mRNA and protein levels. Gut microbial assay showed that GQD treatment increased the relative abundance of Firmicutes and their genera in intestinal microbiota, and increased short-chain fatty acids concentration. Overall, GQD treated ALI by improving metabolic remodeling, affecting immune-related pathways and regulating intestinal microbiota. This study provides a solid scientific basis for promoting the clinical use of GQD in treating ALI.

Protective effects of glycine against lipopolysaccharide-induced intestinal apoptosis and inflammation

Intestinal dysfunction is commonly observed in humans and animals. Glycine (Gly) is a functional amino acid with anti-inflammatory and anti-apoptotic properties. The objective of this study was to test the protective effects of Gly against lipopolysaccharide (LPS)-induced intestinal injury. 28 C57BL/6 mice with a body weight (BW) of 18 ± 2 g were randomly assigned into four groups: CON (control), GLY (orally administered Gly, 5 g/kg BW/day for 6 days), LPS (5 mg/kg BW on day 7, i. p.), and GLY + LPS (Gly pretreatment and LPS administration). Histological alterations, inflammatory responses, epithelial cell apoptosis, and changes of the intestinal microbiota were analyzed. Results showed that, compared with the CON group, mice in the LPS treatment group showed decreased villus height, increased crypt depth, and decreased ratio of villus height to crypt depth, which were significantly attenuated by Gly. Neither LPS nor Gly treatment altered morphology of the distal colon tissues. LPS increased the apoptosis of jejunum and colon epithelial cells and protein abundance of cleaved caspase3 in the jejunum, which were markedly abrogated by Gly. LPS also elevated the mRNA levels of Toll-like receptor 4 (TLR4), myeloid differentiation factor 88 (MYD88), pro-inflammatory cytokines, and chemokines in the jejunum and colon. These alterations were significantly suppressed by Gly. In addition, Gly supplementation attenuated infiltration of CD4+, CD8+ T-lymphocytes, CD11b+ and F4/80+ macrophages in the colon. Furthermore, Gly increased the relative abundance of Mucispirillum, Lachnospiraceae-NK4A136-group, Anaerotruncus, Faecalibaculum, Ruminococcaceae-UCG-014, and decreased the abundance of Bacteroides at genus level. Supplementation with Gly might be a nutritional strategy to ameliorate LPS-induced intestinal injury in mice.

Urinary metabolomics study of vancomycin-associated nephrotoxicity based on ultra-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry

Drug-induced nephrotoxicity is widespread and seriously affects human health. Vancomycin is a classical glycopeptide antibiotic. Vancomycin is widely used for severe infections caused by Gram-positive bacteria, especially methicillin-resistant Staphylococcus aureus but its obvious nephrotoxicity affects the safety of its clinical application. However, the etiology of vancomycin induced kidney injury is not well understood. This study aimed to explore the potential mechanism of vancomycin-induced nephrotoxicity in rats. Vancomycin (400 mgkg^-1) was used to establish kidney injury models in rats. A metabonomic approach was employed using ultra-performance liquid chromatography coupled with quadrupole-time-of-flight mass spectrometry (UHPLC-Q-TOF/MS) to delineate metabolic alterations. As a result, 15, 22, and 37 biomarkers were identified in urine samples from the treatment group compared to the control model on D2, D4, and D7, respectively. Changes in the levels of these metabolites indicated that amino acid metabolism and energy metabolism were disturbed in rats with vancomycin-associated nephrotoxicity. This study revealed the kidney effect of vancomycin, which may provide novel and promising research approaches to vancomycin-induced renal toxicity.

l-Arginine Alleviates LPS-Induced Oxidative Stress and Apoptosis via Activating SIRT1-AKT-Nrf2 and SIRT1-FOXO3a Signaling Pathways in C2C12 Myotube Cells

l-arginine (l-Arg) has been reported to possess a wide range of functions, including anti-inflammatory, anti-oxidative, and anti-apoptosis. However, the role of l-Arg in LPS-induced muscle injury and its potential protective mechanism has not been well elucidated. This study aimed to investigate the effects of l-Arg on the LPS-induced oxidative stress and apoptosis in differentiated C2C12 myotube cells. Our results demonstrated that myotube cells treated with 0.2 mg/mL LPS significantly decreased cell viability. l-Arg treatment significantly suppressed LPS induced ROS accumulation and cell apoptosis. Furthermore, l-Arg improved antioxidant-related enzymes’ activities; increased antioxidant ability via Akt-Nrf2 signaling pathway; maintained the mitochondrial membrane potential (MMP); and enhanced FOXO3a expression, leading to a decrease in the mitochondrial-associated apoptotic proteins. In addition, l-Arg exposure dramatically increased the mRNA and protein expressions of SIRT1. The cytoprotective effect of l-Arg was restricted by the SIRT1 inhibitor EX527, which led to an increase in ROS level, apoptosis rate, and decreased cell MMP. The results also demonstrated that EX527 treatment significantly eliminated the effect of l-Arg on LPS-induced oxidative damage and mitochondria-mediated cell apoptosis. Our findings revealed that l-Arg could be used as a potential nutraceutical in reducing muscle injury via regulating SIRT1-Akt-Nrf2 and SIRT1-FOXO3a-mitochondria apoptosis signaling pathways.

Arginine Regulates NLRP3 Inflammasome Activation Through SIRT1 in Vascular Endothelial Cells

L-arginine (Arg), a semi-essential amino acid, has recently been shown to attenuate inflammatory response during cardiovascular disease. NLRP3 inflammasome serves a central role in amplification of cellular inflammation. In this study, we aimed to confirm the modulatory effect of Arg on NLRP3 inflammasome and the underlying mechanisms in vascular endothelial cells (ECs). Arg suppressed NLRP3 inflammasome activation in ECs stimulated with lipopolysaccharide (LPS) and adenosine triphosphate (ATP). Moreover, treatment with Arg increased the expression of the deacetylase sirtuin 1 (SIRT1) in ECs. Importantly, knockdown of SIRT1 abolished the inhibitory potential of Arg on the activation of NLRP3 inflammasome. Further study indicated that Arg also alleviated LPS plus ATP-induced the generation of reactive oxygen species (ROS) in ECs. In addition, Arg may regulate NLRP3 inflammasome activation partly through suppression of ROS production. In combination, we speculate that Arg exerts an inhibitory effect on the activation of NLRP3 inflammasome in ECs, which may be partly mediated by SIRT1 and ROS.

Investigation of the therapeutic effect of Yinchen Wuling Powder on CCl4-induced hepatic fibrosis in rats by 1H NMR and MS-based metabolomics analysis

Hepatic fibrosis (HF) is a typical consequence of various chronic liver diseases, and there is still no ideal drug for its treatment. Yinchen Wuling Powder (YCWLP), a famous traditional Chinese medicine prescription, is effective for the treatment of icteric hepatitis, hepatic fibrosis, non-alcoholic fatty liver disease and other liver diseases in clinical practices, however, the underlying mechanisms of YCWLP on HF is still unclear. In this study, ¹H NMR and MS-based metabolomics analysis along with body weight change, serum liver function indexes, serum liver fibrosis index and histopathological observations of liver were applied to evaluate the therapeutic effect of YCWLP on hepatic fibrosis and the mechanism associated with this. The results of the pharmacodynamics study show that YCWLP has a significant therapeutic effect on hepatic fibrosis. As for the metabolomics research, 7 metabolites in the plasma samples, 28 in the urine samples and 6 in the liver samples were significantly altered due to the protective effect of YCWLP on CCl₄-induced hepatic fibrosis. These endogenous metabolites are involved in amino acid metabolism, carbohydrate metabolism, glycerophospholipid metabolism and gut bacteria metabolism. These findings suggest that YCWLP could treat hepatic fibrosis by promoting urea circulation and reducing blood ammonia accumulation, improving carbohydrate metabolism and reducing oxidative stress, improving glycerophospholipid metabolism and protecting cell membrane, and regulating intestinal flora metabolism.

Ursolic acid alleviates heat stress-induced lung injury by regulating endoplasmic reticulum stress signaling in mice

Acute lung injury has been reported to be associated with heat stress in various animals. Ursolic acid is a natural pentacyclic triterpenoid compound with multiple bioactivities. However, it remains unknown whether ursolic acid supplementation alleviates heat stress-induced lung injury. In the present study, male Institute of Cancer Research mice were left untreated under a normal temperature condition (23±1°C), receiving orally administrated with vehicle (phosphate buffered saline) or ursolic acid (40 mg/kg BW-1·d-1 for 2 d), and then were subjected to high temperature (41±1°C) for 2 h. Histological alterations, activities of antioxidative enzymes, apoptosis, generation of reactive oxygen species, abundance of inflammatory cytokines, and endoplasmic reticulum stress-related proteins were analyzed. Compared with the controls, heat stress treatment led to enhanced apoptosis, increased H2O2 production, and upregulated protein levels of inflammatory cytokines in the serum, including tumor necrosis factor alpha, interleukin-6, and interleukin-1 beta. Activities of malondialdehyde, lactate dehydrogenase, and myeloperoxidase were increased, while the activities for superoxide dismutase and catalase were reduced in lung tissues of mice. All these alterations were significantly prevented by ursolic acid administration. Further study showed that heat stress led to activation of protein kinase-like ER kinase eukaryotic initiation factor 2 alpha -the transcription factor CCAAT-enhancer-binding protein homologous protein (CHOP) signaling, which was attenuated by ursolic acid supplementation. These findings indicated that ursolic acid pretreatment protected lung tissues against heat stress-induced injury by regulating inflammatory cytokines and unfolded protein response in mice. Ursolic acid supplementation might be a therapeutic strategy to alleviate high temperature-induced lung injury in humans and animals.

Mushroom Inonotus sanghuang alleviates experimental pulmonary fibrosis: Implications for therapy of pulmonary fibrosis

Mushroom Inonotus sanghuang has been characterized as a traditional medicine in China and has pharmacological activities to treat inflammation, gastroenteric dysfunction, and cancer. Recently, we reported the impact of Inonotus sanghuang extract (ISE) from ethyl acetate fraction on bleomycin (BLM)-induced acute lung injury in mice. Here, we aimed to investigate ISE's impact on pulmonary fibrosis using in vivo and in vitro models and the underlying mechanisms. To evaluate pulmonary fibrosis, female C57BL/6 mice fed ISE (0% or 0.6% in diet) for 4 weeks were instilled intratracheally with BLM and then continued the same diet before the end of the experiment. A549 cells were used to evaluate the epithelial-mesenchymal transition (EMT). Feeding ISE improved BLM-treated mice's survival via decreasing lung infiltrating cells and fibrosis, followed by reducing hydroxyproline content, collagen deposition, and mesenchymal markers (α-SMA and vimentin) while increasing epithelial marker E-cadherin. ISE also suppressed the TGF-β expression, Smad2/3 phosphorylation, and EMT-related transcription factor Snail upon BLM instillation. Iin vitro study demonstrated that ISE inhibited TGF-β-induced EMT-like phenotype and cell behaviors, the expression of α-SMA and vimentin, and prevented E-cadherin reduction of A549 cells. Consistent with in vivo study, ISE abrogated p-Smad2/3, and Snail expression. Finally, the influence of ISE on EMT was not due to ISE toxicity. Our findings indicated that ISE effectively attenuated BLM-induced lung fibrosis. These ISE properties were thought to be involved in interfering TGF-β, Smad2/3 phosphorylation, and EMT process, suggesting that the material has the potential health benefits to improve lung fibrosis.

Epithelial Dysfunction in Lung Diseases: Effects of Amino Acids and Potential Mechanisms

Lung diseases affect millions of individuals all over the world. Various environmental factors, such as toxins, chemical pollutants, detergents, viruses, bacteria, microbial dysbiosis, and allergens, contribute to the development of respiratory disorders. Exposure to these factors activates stress responses in host cells and disrupt lung homeostasis, therefore leading to dysfunctional epithelial barriers. Despite significant advances in therapeutic treatments for lung diseases in the last two decades, novel interventional targets are imperative, considering the side effects and limited efficacy in patients treated with currently available drugs. Nutrients, such as amino acids (e.g., arginine, glutamine, glycine, proline, taurine, and tryptophan), peptides, and bioactive molecules, have attracted more and more attention due to their abilities to reduce oxidative stress, inhibit apoptosis, and regulate immune responses, thereby improving epithelial barriers. In this review, we summarize recent advances in amino acid metabolism in the lungs, as well as multifaceted functions of amino acids in attenuating inflammatory lung diseases based on data from studies with both human patients and animal models. The underlying mechanisms for the effects of physiological amino acids are likely complex and involve cell signaling, gene expression, and anti-oxidative reactions. The beneficial effects of amino acids are expected to improve the respiratory health and well-being of humans and other animals. Because viruses (e.g., coronavirus) and environmental pollutants (e.g., PM2.5 particles) induce severe damage to the lungs, it is important to determine whether dietary supplementation or intravenous administration of individual functional amino acids (e.g., arginine-HCl, citrulline, N-acetylcysteine, glutamine, glycine, proline and tryptophan) or their combinations to affected subjects may alleviate injury and dysfunction in this vital organ.

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.

The Central Role of Clinical Nutrition in COVID-19 Patients During and After Hospitalization in Intensive Care Unit

The COVID-19-positive patient who is subject to a hyperinflammatory condition associated with lung injury with the development of pneumonia is hospitalized in the intensive care unit. Before resolving and overcoming the "cytokine storm," with overexpression of pro-inflammatory interleukins (IL-, Il-6), this patient will be intubated for more than 48 h and therefore needs adequate nutrition. Malnutrition can lead to sarcopenia with a decrease in lean body mass and worsening of the inflammatory state underway. In addition, severe debilitation, if not corrected with adequate nutrition, can greatly lengthen rehabilitation times with prolonged hospitalization, increased costs, and reduced turn over already in crisis due to the health emergency caused by coronavirus. The aim of this study is to focus attention on the nutritional importance that must be provided in case of COVID-19 together with pharmacological treatments to lower the number of circulating proinflammatory cytokines. Oral, enteral, and parenteral nutrition should always be carried out according to the patient's condition and, in the case of a hyperinflammatory patient, such as the one affected by COVID-19, it has been shown that the supplementation of amino acids helps to lower the inflammatory state and promotes normal physiological recovery.

Pterostilbene prevents LPS-induced early pulmonary fibrosis by suppressing oxidative stress, inflammation and apoptosis in vivo

Early pulmonary fibrosis after acute lung injury leads to poor prognosis and high mortality. Pterostilbene (Pts), a bioactive component in blueberries, possesses anti-inflammatory, antioxidative and antifibrotic properties. However, the effects of Pts on lipopolysaccharide (LPS)-induced pulmonary fibrosis are still unknown. In our study, the Pts group showed lower lung injury and fibrosis scores, and lower levels of hydroxyproline and protein (collagen I and transforming growth factor-β) than the scores and levels in mice treated with LPS. MMP-1 was the degrading enzyme of collagen I and LPS caused the inhibition of MMP-1, disturbing the degradation of collagen. Additionally, Pts remarkably reversed the LPS-induced inhibition of interleukin-10 and the release of tumor necrosis factor-α, interleukin-6 and interleukin-1β. In terms of cellular pathways, Pts treatment ameliorated LPS-activated nuclear factor kappa B (NF-κB) and NOD-like receptor NLRP3 signaling. Besides, LPS-induced low levels of A20 could be activated by Pts. In addition, Pts treatment reversed the high levels of Caspase-3, poly ADP-ribose polymerase (PARP) and Bcl2-associated X protein (Bax) expression and the low levels of B cell lymphoma/lewkmia-2 (Bcl2) that had been induced by LPS. Moreover, oxidative stress is also involved in the pathogenesis of fibrosis. Our findings indicate that LPS injection triggered the production of myeloperoxidase (MPO) and malondialdehyde (MDA) and the depletion of superoxide dismutase (SOD) and glutathione (GSH), and that these effects were notably reversed by treatment with Pts. In addition, Pts induced the dissociation of Kelch-like epichlorohydrin-associated protein-1 (Keap-1) and NF-E2 related factor-2 (Nrf2) and the activation of downstream genes (heme oxygenase-1, NAD(P)H:quinine oxidoreductase, glutamate-cysteine ligase catalytic subunit and glutamate-cysteine ligase modifier). In conclusion, oxidative stress, apoptosis and inflammation are involved in early pulmonary fibrosis and Pts exerts a protective effect by activating Keap-1/Nrf2, inhibiting caspase-dependent A20/NF-κB and NLRP3 signaling pathways.

Ophiocordyceps lanpingensis polysaccharides attenuate pulmonary fibrosis in mice

Idiopathic pulmonary fibrosis (IPF) is a fatal lung disease with growing prevalence. Currently available therapies for treating IPF are not desirable due to the limited efficacy and multiple side effects. Ophiocordyceps lanpingensis is one strain of entomogenous fungi, which has been collected from the eastern part of the Himalayas. This study revealed that O. lanpingensis polysaccharides (OLP) could attenuate bleomycin (BLM) induced lung fibrosis in mice. Results showed that OLP treatments significantly reduced BLM-induced collagen deposition and decreased the accumulation of macrophages. The oxidative stress of the lung was alleviated by OLP. The expression levels of pro-inflammatory and pro-fibrogenic factors in OLP groups were also decreased compared with those in the BLM group, which might explain the improved alveolar integrity and function in the OLP treated groups. Our findings indicated that OLP treatment could alleviate pulmonary fibrosis progression mainly through reducing the recruitment of macrophages to the lungs.

Glycine Attenuates Lipopolysaccharide-Induced Acute Lung Injury by Regulating NLRP3 Inflammasome and NRF2 Signaling

Glycine supplementation has been reported to alleviate lipopolysaccharide (LPS)-induced lung injury in mice. However, the underlying mechanisms responsible for this beneficial effect remain unknown. In the present study, male C57BL/6 mice were treated with aerosolized glycine (1000 mg in 5 mL of 0.9% saline) or vehicle (0.9% saline) once daily for 7 continuous days, and then were exposed to aerosolized LPS (5 mg in 5 mL of 0.9% saline) for 30 min to induce lung injury. Sera and lung tissues were collected 24 h post LPS challenge. Results showed that glycine pretreatment attenuated LPS-induced decreases of mucin at both protein and mRNA levels, reduced LPS-triggered upregulation of pro-inflammatory cytokines, such as tumor necrosis factor-α (TNF-α), interferons, granulocyte-macrophage colony-stimulating factor (GM-CSF), and interleukins. Further study showed that glycine-reduced LPS challenge resulted in the upregulation of nuclear factor κB (NF-κB), nucleotide binding domain (NOD)-like receptor protein 3 (NLRP3) inflammasome. In addition, LPS exposure led to the downregulation of NRF2 and downstream targets, which were significantly improved by glycine administration in the lung tissues. Our findings indicated that glycine pretreatment prevented LPS-induced lung injury by regulating both NLRP3 inflammasome and NRF2 signaling.

Dietary melatonin attenuates chromium-induced lung injury via activating the Sirt1/Pgc-1α/Nrf2 pathway

Exposure to chromium (Cr) causes a number of respiratory diseases, including lung cancer and pulmonary fibrosis. However, there is currently no safe treatment for Cr-induced lung damage. Here, we used in vivo and in vitro approaches to examine the protective effects of melatonin (MEL) on Cr-induced lung injury and to identify the underlying molecular mechanisms. We found that treatment of rats or a mouse lung epithelial cell MLE-12 with MEL attenuated K₂Cr₂O₇-induced lung injury by reducing the production of oxidative stress and inflammatory mediators and inhibiting cell apoptosis. MEL treatment upregulated the expression of silent information regulator 1 (Sirt1), which deacetylated the transcriptional coactivator peroxisome proliferator-activated receptor-γ coactivator-1α (Pgc-1α). In turn, this increased the expression of the transcription factor nuclear factor erythroid 2-related factor 2 (Nrf2) and key anti-oxidant target genes. These results suggest that melatonin attenuates chromium-induced lung injury via activating the Sirt1/Pgc-1α/Nrf2 pathway. Dietary MEL supplement may be a potential new strategy for the treatment of Cr poisoning.