Aberrant purine metabolism in allergic asthma revealed by plasma metabolomics

Weizmannia coagulans BC99 alleviates hyperuricemia and oxidative stress via DAF-16/SKN-1 activation in Caenorhabditis elegan

Introduction

Hyperuricemia (HUA) refers to the presence of excess uric acid (UA) in the blood, which increases the risk of chronic kidney disease and gout. Probiotics have the potential to alleviate HUA.

Methods

This study established a hyperuricemia model using Caenorhabditis elegans (C. elegans), and studied the anti-hyperuricemia activity and potential mechanisms of Weizmannella coagulans BC99 (W. coagulans) at different concentrations (107 CFU/mL BC99, 108 CFU/mL BC99). Subsequently, we utilized UPLC-Q-TOF/MS to investigate the impact of BC99 on endogenous metabolites in C. elegans and identified pathways and biomarkers through differential metabolomics analysis.

Results

The results of this study showed that BC99 treatment significantly reduced the expression of P151.2 and T22F3.3 (p < 0.05), reduced the levels of UA and xanthine oxidase (XOD) in nematodes (p < 0.05), while extending their lifespan and movement ability (p < 0.05). Mechanistically, BC99 activates the transcription factors DAF-16 and SKN-1, thereby inducing the expression of stress response genes, enhancing the activity of antioxidant enzymes and tolerance to heat stress in the body, and reducing the production of ROS (p < 0.001). This effect was most significant in the H-BC99 group. Furthermore, non-targeted metabolomics indicated that BC99 predominantly regulated pathways associated with amino acid metabolism (Carnosine), glycerophospholipid metabolism, and purine metabolism.

Discussion

These results underscore BC99 as an effective and economical adjunct therapeutic agent for hyperuricemia, providing a scientific basis for further development and application.

Green carbon dots derived from Zingiberis Rhizoma Carbonisatum alleviate ovalbumin-induced allergic rhinitis

Background

Allergic rhinitis (AR) affects up to 40% of the population, leading to significant healthcare expenditures. Current mainstream treatments, while effective, can lead to side effects and do not address the underlying immunological imbalances. Zingiberis Rhizoma Carbonisatum (ZRC), the partially charred product of Zingiberis Rhizoma (ZR), has been widely used clinically in China since ancient times to treat respiratory disorders.

Methods

Inspired by the similarity between high-temperature pyrolysis and carbonization processing of herbal medicine, ZRC derived CDs (ZRC-CDs) were extracted and purified through several procedures. Then, the physicochemical characteristics of CDs were delineated through a suite of characterization methods. Moreover, our investigation zeroed in on elucidating the ameliorative impacts of CDs on ovalbumin-induced rat models alongside their underlying mechanisms.

Results

ZRC-CDs with particle sizes ranging from 1.0 to 3.5 nm and rich surface functional groups. Additionally, we observed that ZRC-CDs significantly attenuated nasal symptoms and pathological damage in ovalbumin-induced AR rats, and modulated lipid metabolism and type 2 inflammatory responses. They also inhibit PI3K/AKT and JAK/STAT pathways, which are associated with metabolism and inflammation. Importantly, ZRC-CDs demonstrated high biocompatibility, underscoring their potential as a novel therapeutic agent.

Conclusion

ZRC-CDs offer a promising alternative for AR treatment and could help facilitate broader clinical use of the ZRC. In addition, the exploration of the inherent bioactivity of CDs can help to broaden their biological applications.

Microbiome modifications by steroids during viral exacerbation of asthma and in healthy mice

In the present studies, the assessment of how viral exacerbation of asthmatic responses with and without pulmonary steroid treatment alters the microbiome in conjunction with immune responses presents striking data. The overall findings identify that although steroid treatment of allergic animals diminished the severity of the respiratory syncytial virus (RSV)-induced exacerbation of airway function and mucus hypersecretion, there were local increases in IL-17 expression. Analysis of the lung and gut microbiome suggested that there are differences in RSV exacerbation that are further altered by fluticasone (FLUT) treatment. Using metagenomic inference software, PICRUSt2, we were able to predict that the metabolite profile produced by the changed gut microbiome was significantly different with multiple metabolic pathways and associated with specific treatments with or without FLUT. Importantly, measuring plasma metabolites in an unbiased manner, our data indicate that there are significant changes associated with chronic allergen exposure, RSV exacerbation, and FLUT treatment that are reflective of responses to the disease and treatment. In addition, the changes in metabolites appeared to have contributions from both host and microbial pathways. To understand if airway steroids on their own altered lung and gut microbiome along with host responses to RSV infection, naïve animals were treated with lung FLUT before RSV infection. The naïve animals treated with FLUT before RSV infection demonstrated enhanced disease that corresponded to an altered microbiome and the related PICRUSt2 metagenomic inference analysis. Altogether, these findings set the foundation for identifying important correlations of severe viral exacerbated allergic disease with microbiome changes and the relationship of host metabolome with a potential for early life pulmonary steroid influence on subsequent viral-induced disease.NEW & NOTEWORTHY These studies outline a novel finding that airway treatment with fluticasone, a commonly used inhaled steroid, has significant effects on not only the local lung environment but also on the mucosal microbiome, which may have significant disease implications. The findings further provide data to support that pulmonary viral exacerbations of asthma with or without steroid treatment alter the lung and gut microbiome, which have an impact on the circulating metabolome that likely alters the trajectory of disease progression.

Combining metabolomics with network pharmacology to reveal the therapeutic mechanism of Dingchuan Decoction in rats with OVA-induced allergic asthma

Dingchuan Decoction (DCD) is a traditional Chinese medicine prescription commonly used in the treatment of asthma, but the mechanism of DCD in treating asthma has not yet been determined. In this study, we employed a combination of metabolomics and network pharmacology to investigate the mechanism of DCD in treating asthma. An allergic asthma rat model was induced by ovalbumin (OVA). Metabolomics based on 1H NMR and UHPLC-MS was used to identify differential metabolites and obtain the major metabolic pathways and potential targets. Network pharmacology was utilized to explore potential targets of DCD for asthma treatment. Finally, the results of metabolomics and network pharmacology were integrated to obtain the key targets and metabolic pathways of DCD for the therapy of asthma, and molecular docking was utilized to validate the key targets. A total of 76 important metabolites and 231 potential targets were identified through metabolomics. Using network pharmacology, 184 potential therapeutic targets were obtained. These 184 targets were overlaid with the 231 potential targets obtained through metabolomics and were analyzed in conjunction with metabolic pathways. Ultimately, the key targets were identified as aldehyde dehydrogenase 2 (ALDH2) and amine oxidase copper-containing 3 (AOC3), and the relevant metabolic pathways affected were glycolysis and gluconeogenesis as well as arginine and proline metabolism. Molecular docking showed that the key targets had high affinity with the relevant active ingredients in DCD, which further demonstrated that DCD may exert therapeutic effects by acting on the key targets. The present study demonstrated that DCD can alleviate OVA-induced allergic asthma and that DCD may have a therapeutic effect by regulating intestinal flora and polyamine metabolism through its effects on ALDH2 and AOC3.

Differential immunometabolic responses to Delta and Omicron SARS-CoV-2 variants in golden syrian hamsters

Delta (B.1.617.2) and Omicron (B.1.1.529) variants of SARS-CoV-2 represents unique clinical characteristics. However, their role in altering immunometabolic regulations during acute infection remains convoluted. Here, we evaluated the differential immunopathogenesis of Delta vs. Omicron variants in Golden Syrian hamsters (GSH). The Delta variant resulted in higher virus titers in throat swabs and the lungs and exhibited higher lung damage with immune cell infiltration than the Omicron variant. The gene expression levels of immune mediators and metabolic enzymes, Arg-1 and IDO1 in the Delta-infected lungs were significantly higher compared to Omicron. Further, Delta/Omicron infection perturbed carbohydrates, amino acids, nucleotides, and TCA cycle metabolites and was differentially regulated compared to uninfected lungs. Collectively, our data provide a novel insight into immunometabolic/pathogenic outcomes for Delta vs. Omicron infection in the GSH displaying concordance with COVID-19 patients associated with inflammation and tissue injury during acute infection that offered possible new targets to develop potential therapeutics.

Integration of metabolomics and transcriptomics reveals the therapeutic mechanism underlying Chelidonium majus L. in the treatment of allergic asthma

BACKGROUND

Chelidonium majus is a well-known traditional Chinese medicine, and has been reported of the effect in relieving cough and asthma. However, the mechanism of action is still unknown.

METHODS

Asthmatic SD rats were first sensitized and established through ovalbumin (OVA) motivation. Subsequently, Hematoxylin and eosin (H&E) staining, Masson's trichrome (Masson) staining, Periodic acid-Schiff (PAS) staining and inflammatory cytokines assay of interleukin (IL)-4, IL-6, IL-17 were implemented to evaluate the protective effects of Chelidonium majus on asthma. Then, the effects of Chelidonium majus and their molecular mechanisms of action on asthma were detected based on the integration of transcriptomics and metabolomics analyses.

RESULTS

After administration with Chelidonium majus, the histological injuries of inflammation, collagen deposition and mucus secretion in lungs were attenuated and the serum inflammatory cytokines perturbations were also converted. Furthermore, integrated analysis revealed that after Chelidonium majus treatment, 7 different expression genes (DEGs) (Alox15, P4ha1, Pla2g16, Pde3a, Nme1, Entpd8 and Adcy9) and 9 metabolic biomarkers (ADP, Xanthosine, Hypoxanthine, Inosine, prostaglandin E2 (PGE2), prostaglandin F2a (PGF2a), phosphatidylserine, Creatine and LysoPC (10:0)) were discovered to be connected with the enrichment metabolic pathways, including Purine metabolism, Arachidonic acid metabolism, Arginine and proline metabolism and Glycerophospholipid metabolism. The obtained metabolic biomarkers and DEGs were mainly related to energy metabolism and inflammation, and may be potential therapeutic targets.

CONCLUSION

Chelidonium majus relieved OVA-induced asthma in rats by regulating the Alox15, P4ha1, Pla2g16, Pde3a, Nme1, Entpd8 and Adcy9 genes expression to restore the disorders in energy metabolism and inflammation.

Lactobacillus paracasei-derived extracellular vesicles alleviate neutrophilic asthma by inhibiting the JNK pathway in airway epithelium

BACKGROUND

Lactobacillus paracasei has been known to reduce airway resistance and inflammation in asthma. However, the therapeutic effect of its extracellular vesicles (EVs) in patients with asthma remains unclear.

METHODS

To validate the clinical relevance of L. paracasei-derived EVs (LpEV) in asthma, the composition of gut microbial EVs was verified by metagenomics in LPS-induced C57BL/6 mice. The components of proteins and metabolites in LpEV were identified by peptide mass fingerprinting and metabolomic analysis. The serum levels of specific IgG1 or IgG4 antibodies to LpEV were compared by ELISA between patients with eosinophilic asthma (EA, n = 10) and those with neutrophilic asthma (NA, n = 10) as well as with healthy controls (HCs, n = 10). Finally, therapeutic effects of LpEV and their metabolites in asthma were validated in vivo/in vitro.

RESULTS

Significantly lower proportions of EVs derived from Lactobacillus at the genus level were noted in mice with NA than in control mice. Moreover, the serum levels of LpEV-specific IgG4, but not IgG1, were lower in patients with NA than in those with EA or in HCs and positively correlated with FEV1 (%) values. In addition, oral administration of LpEV reduced airway resistance and inflammation in mice with NA. Finally, LpEV and their 3 metabolites (dodecanoic acid, palmitoleic acid, and D-(-)-tagatose) significantly inhibited JNK phosphorylation/IL-8 production in airway epithelium in vitro.

CONCLUSIONS

These findings suggest that LpEV may have a therapeutic potential targeting NA by suppressing the JNK pathway and proinflammatory cytokine production in airway epithelium.

UHPLC/MS-based metabolomics of asthmatic mice reveals metabolic changes in group 2 innate lymphoid cells

Helper Th2-type immune responses are essential in allergic airway diseases, including asthma and allergic rhinitis. Recent studies have indicated that group 2 innate lymphoid cells (ILC2s) play a crucial role in the occurrence and development of asthma. However, the metabolic profile of ILC2s and their regulatory mechanisms in asthma remain unclear. Therefore, we established two asthma mouse models: an ovalbumin (OVA)-induced asthma model and an IL-33-induced asthma model. We then used ultra-high-performance liquid chromatography/mass spectrometry (UHPLC/MS) to conduct high-throughput untargeted metabolic analysis of ILC2s in the lung tissues of the asthma models. The identified metabolites primarily consisted of lipids, lipid-like molecules, benzene, organic acids, derivatives, and organic oxidation compounds. Specifically, 34 differentially accumulated metabolites influenced the metabolic profiles of the control and OVA-induced asthma model groups. Moreover, the accumulation of 39 metabolites significantly differed between the Interleukin 33 (IL-33) and control groups. These differentially accumulated metabolites were mainly involved in pathways such as sphingolipid, oxidative phosphorylation, and fatty acid metabolism. This metabolomic study revealed, for the first time, the key metabolites and metabolic pathways of ILC2s, revealing new aspects of cellular metabolism in the context of airway inflammation. These findings not only contribute to unraveling the pathogenesis of asthma but also provide a crucial theoretical foundation for the future development of therapeutic strategies targeting ILC2s.

Covalent conjugation with quercetin mitigates allergenicity of the bee pollen allergen Bra c p in a murine model

Profilin family members are highly conserved food allergens that can cause widespread cross-allergic reactions. Our previous research has demonstrated that the covalent conjunction with quercetin can disrupt the conformational epitopes of a profilin allergen, Bra c p. In this study, we further investigated the intrinsic molecular mechanisms using molecular dynamics simulations. Moreover, the allergenic potential of Bra c p and its conjugate with quercetin was assessed in BALB/c mice. The results showed that continuous interaction with quercetin increased the molecular motion of Bra c p, causing changes to its α-helices and exposing hydrophobic residues which altered antigenic epitopes. Additionally, mice treated with Bra c p-quercetin conjugate showed reduced allergic reactions compared to those treated with Bra c p alone by regulating purine metabolism, calcium signaling, and CD4+CD25+ Tregs proportion. Quercetin conjugation decreases the allergenicity of Bra c p, providing a scientific foundation for reducing the profilin allergens in food.

Metabolomics in Animal Models of Bronchial Asthma and Its Translational Importance for Clinics

Bronchial asthma is an extremely heterogenous chronic respiratory disorder with several distinct endotypes and phenotypes. These subtypes differ not only in the pathophysiological changes and/or clinical features but also in their response to the treatment. Therefore, precise diagnostics represent a fundamental condition for effective therapy. In the diagnostic process, metabolomic approaches have been increasingly used, providing detailed information on the metabolic alterations associated with human asthma. Further information is brought by metabolomic analysis of samples obtained from animal models. This article summarizes the current knowledge on metabolomic changes in human and animal studies of asthma and reveals that alterations in lipid metabolism, amino acid metabolism, purine metabolism, glycolysis and the tricarboxylic acid cycle found in the animal studies resemble, to a large extent, the changes found in human patients with asthma. The findings indicate that, despite the limitations of animal modeling in asthma, pre-clinical testing and metabolomic analysis of animal samples may, together with metabolomic analysis of human samples, contribute to a novel way of personalized treatment of asthma patients.

Integrated metabolome-microbiome analysis investigates the different regulations of Pudilan Xiaoyan oral liquid in young rats with acute pharyngitis compared to adult rats

BACKGROUND

Pudilan Xiaoyan Oral Liquid (PDL) is a famous traditional Chinese prescription recorded in the Chinese Pharmacopeia, which is widely used to treat inflammatory diseases of the respiratory tract in children and adults. However, the endogenous changes in children and adults with PDL in the treatment of acute pharyngitis remain unclear.

PURPOSE

The differential regulatory roles of PDL in endogenous metabolism and gut microbes in young and adult rats were investigated with a view to providing a preclinical data reference for PDL in medication for children.

METHODS

An acute pharyngitis model was established, and serum levels of inflammatory factors and histopathology were measured. This study simulated the growth and development of children in young rats and explored the endogenous metabolic characteristics and intestinal microbial composition after the intervention of PDL by using serum metabolomic technique and 16S rRNA high-throughput sequencing technique.

RESULTS

The results showed that PDL had therapeutic effects on young and adult rats with acute pharyngitis. Sixteen biomarkers were identified by metabolomics in the serum of young rats and 23 in adult rats. PDL can also affect intestinal microbial diversity and community richness in young and adult rats. Alloprevotella, Allobaculum, Alistipes, Bifidobacterium, and Enterorhabdus were prominent bacteria in young rats. Bacteria from the phylum Firmicutes of the adult rats changed more significantly under the treatment of PDL. In young rats, amino acid metabolism was the primary regulatory mode of PDL, whereas, in adult rats, glycerophospholipid metabolism was studied.

CONCLUSION

The regulation of PDL on the serum metabolite group and intestinal microflora in young rats was different from that in adult rats, indicating the necessity of an independent study on children's medication. PDL may also exert therapeutic effects on young and adult rats by regulating gut microbial homeostasis. The results support the clinical application of PDL.

Combined microbiome and metabolome analysis of gut microbiota and metabolite interactions in chronic spontaneous urticaria

Background

The pathogenesis of chronic spontaneous urticaria (CSU) is unclear, and it turned out to be involved in biological processes, such as autoimmunity, autoallergy, inflammation, and coagulation. The gut microbiota plays an important role in immune and inflammatory diseases. However, the relationship between chronic spontaneous urticaria and the gut microbiota remains unknown.

Methods

The stool and serum samples were taken from 15 CSU patients and 15 normal controls. Changes in the composition of gut microbiota and serum metabolism in CSU patients and normal controls were analyzed by 16S ribosomal RNA (rRNA) gene sequencing and untargeted metabolomics.

Results

The results of 16S rRNA gene sequencing showed that compared with normal controls, CSU patients had increased α-diversity of gut microbiota and significant differences in β-diversity. At the phylum level, the relative abundance of Firmicutes increased and the relative abundance of Bacteroidetes and Proteobacteria decreased in CSU patients compared with healthy controls. At the genus level, six kinds of bacteria were significantly enriched in CSU patients and five in normal controls. Metabolomic analysis revealed altered levels of metabolites such as unsaturated fatty acids and purines. Correlation analysis of gut microbiota and metabolites showed that Lachnospira was negatively correlated with arachidonic acid, and Gemmiger was also negatively correlated with (±)8-HETE.

Conclusion

This study suggests that changes in gut microbiota and metabolites may play a role in immune and inflammatory pathways in the pathogenesis of CSU patients.

Effects of carbon black nanoparticles and high humidity on the lung metabolome in Balb/c mice with established allergic asthma

In respiratory diseases, the induction of allergic asthma has gradually aroused public concerns. Co-exposures of environmental risk factors such as nanoparticles and high humidity could play important roles in the development of allergic asthma. However, the relevant researches are still lacking and the involved mechanisms, especially metabolic changes, remain unclear. We took the lead in studying the combined induction effect and underlying mechanisms of carbon black nanoparticles (CB NPs) and high humidity on allergic asthma. In this work, murine models of allergic asthma were established with ovalbumin under the single and combined exposures of 15 μg/kg CB NPs and 90% relative humidity. The two risk factors, particularly their co-exposure, exhibited adjuvant effect on airway hyperresponsiveness, remodeling, and inflammation in Balb/c mice. Untargeted metabolomics identified the potential biomarkers in lung for asthma occurrence and for asthma exacerbation caused by CB NPs and high humidity. The significantly dysregulated metabolic pathways in asthmatic mice were proposed, and the disturbed metabolic pathways under the exposures of CB NPs and/or high humidity were mainly implicated in asthma symptoms. This work sheds light on the understanding for health risks of NP pollutions and high environmental humidity and contributes to useful biomarker identification and asthma control.

Efficacy and Safety of Lactobacillus reuteri CCFM1040 in Allergic Rhinitis and Asthma: A Randomized, Placebo-Controlled Trial

The coexistence of allergic rhinitis (AR) and asthma reinforces the concept of “one airway, one disease,” which has prompted the exploration for a single intervention to treat both diseases. Lactobacillus reuteri CCFM1040 (CCFM1040) was found to be an inhibitor of the common pathogenesis of AR and asthma in our previous studies. This study presented a randomized, placebo-controlled trial to investigate the clinical effects of CCFM1040 on both diseases. The total symptom score (TSS), the quality of life (QoL), and the modulation in the gut microbiota of patients with AR, the Asthma Control and Test (ACT) of patients with asthma, and the safety of both AR and asthma were measured. In patients with AR, CCFM1040 numerically decreased TSS, Rhinoconjunctivitis Quality of Life Questionnaire (RQLQ), 3 nasal scores in TSS (nasal congestion, watery eyes, and rhinorrhea), and sleep and significantly improved (P = 0.014) non-nose/eye symptoms. The ACT score was numerically increased in patients with asthma (from partially controlled to well-controlled). Significant microbial (from class level to genus level) and metabolic differences (P < 0.05) were found in patients with AR. No adverse reactions were observed. No effect on the blood and urine routine indexes. CCFM1040 has a potential benefit on both diseases. Further studies based on these findings will help to optimize the management of AR and asthma.

The preliminary investigation of potential response biomarkers to PAHs exposure on childhood asthma

BACKGROUND

Exposure to polycyclic aromatic hydrocarbons (PAHs) is a potential risk factor for asthma prevalence. This study aims to explore whether PAHs exposure is associated with childhood asthma by altering microbial diversity and metabolic profiles.

METHODS

Thirty children with asthma and 30 children as control in Nanjing, China were recruited. Urinary 1-hydroxypyrene (1-OHPyr) level was determined by UPLC-Orbitrap-MS as a PAHs exposure biomarker. Logistic regression was conducted to investigate the association between 1-OHPyr and childhood asthma. Microbial diversity was analyzed by 16S rRNA gene sequencing. Metabolic profiles were obtained by UPLC-Orbitrap-MS methods. Differential microbiota and metabolites were screened and selected as response biomarkers or intermediates. Mediation analysis was conducted to assess the association between PAHs and asthma mediated by intermediates.

RESULTS

Participating children with and without asthma aged 6.43 ± 2.23 years. The urinary 1-OHPyr level ranged from 0.10 to 1.51 μmol/mol (creatinine corrected) in the participants. The urinary 1-OHPyr level was associated with childhood asthma (OR = 7.21, 95% CI: 1.03-50.42 per 1 μmol/mol unit). Microbial diversity was decreased in the group with asthma and there was a significant shift in the abundance of Proteobacteria (at the phylum level), Veillonella and Prevotella (at the genus level). The enrichment pathway analysis showed that differentially expressed metabolites were involved in purine metabolism, amino acid metabolism, and lipid and fatty acid metabolism. The urinary 1-OHPyr level was associated with the abundance of Actinomyces sp. oral clone IO076 and 7-methylguanine that showed a mediation effect on the association between urinary 1-OHPyr levels and childhood asthma by mediation analysis.

CONCLUSIONS

Urinary 1-OHPyr exposure was associated with childhood asthma, microbial diversity, and metabolic profiles. Microbial diversity and metabolic profiles may be intermediates as response biomarkers to PAHs exposure in childhood asthma. Further research is needed to confirm these study results and determine the underlying mechanism.

The Myristic Acid:Docosahexaenoic Acid Ratio Versus the n-6 Polyunsaturated Fatty Acid:n-3 Polyunsaturated Fatty Acid Ratio as Nonalcoholic Fatty Liver Disease Biomarkers

It is well established that diets containing an increased omega-6 polyunsaturated fatty acid (n-6 PUFA) to omega-3 polyunsaturated fatty acid (n-3 PUFA) ratios are linked to inflammation and chronic diseases such as nonalcoholic fatty liver disease (NAFLD). However, the influence of an elevated n-6 PUFA:n-3 PUFA ratio in the tissues requires clarification. Herein, we identified primary experimental and clinical studies where it is possible to compare the performance of the myristic acid (Myr):docosahexaenoic acid (DHA) and n-6 PUFA:n-3 PUFA ratios in the liver and/or serum as potential NAFLD biomarkers. Articles were included if quantitative values of n-6 PUFA, n-3 PUFA, Myr, DHA, and information about liver inflammation or liver disease progression parameters were provided. Overall, most experimental (91.6%) and clinical studies (87.5%) reported higher Myr:DHA ratios associated with inflammation and/or NAFLD progression than the n-6 PUFA:n-3 PUFA ratio. We conclude that the Myr:DHA ratio represents a better biomarker of NAFLD than the n-6 PUFA:n-3 PUFA ratio. Future studies are necessary for verifying this observation.

Abnormalities in Gut Microbiota and Metabolism in Patients With Chronic Spontaneous Urticaria

Background

Increasing evidence suggests that the gut microbiome plays a role in the pathogenesis of allergy and autoimmunity. The association between abnormalities in the gut microbiota and chronic spontaneous urticaria (CSU) remains largely undefined.

Methods

Fecal samples were obtained from 39 patients with CSU and 40 healthy controls (HCs). 16S ribosomal RNA (rRNA) gene sequencing (39 patients with CSU and 40 HCs) and untargeted metabolomics (12 patients with CSU and 12 HCs) were performed to analyze the compositional and metabolic alterations of the gut microbiome in CSU patients and HCs.

Results

The 16S rRNA gene sequencing results showed a significant difference in the β-diversity of the gut microbiota, presented as the Jaccard distance, between CSU patients and HCs. No significant differences were found in the α-diversity of the gut microbiota between patients and HCs. At the phylum level, the major bacteria in the gut microbiome of patients with CSU were Firmicutes, Bacteroidetes, Proteobacteria, and Actinobacteria. At the genus level, Lactobacillus, Turicibacter, and Lachnobacterium were significantly increased and Phascolarctobacterium was decreased in patients with CSU. PICRUSt and correlation analysis indicated that Lactobacillus, Turicibacter, and Phascolarctobacterium were positively related to G protein-coupled receptors. Metabolomic analysis showed that α-mangostin and glycyrrhizic acid were upregulated and that 3-indolepropionic acid, xanthine, and isobutyric acid were downregulated in patients with CSU. Correlation analysis between the intestinal microbiota and metabolites suggested that there was a positive correlation between Lachnobacterium and α-mangostin.

Conclusions

This study suggests that disturbances in the gut microbiome composition and metabolites and their crosstalk or interaction may participate in the pathogenesis of CSU.

Metabolomics in asthma: A platform for discovery

Asthma, characterized by airway hyperresponsiveness, inflammation and remodeling, is a chronic airway disease with complex etiology. Severe asthma is characterized by frequent exacerbations and poor therapeutic response to conventional asthma therapy. A clear understanding of cellular and molecular mechanisms of asthma is critical for the discovery of novel targets for optimal therapeutic control of asthma. Metabolomics is emerging as a powerful tool to elucidate novel disease mechanisms in a variety of diseases. In this review, we summarize the current status of knowledge in asthma metabolomics at systemic and cellular levels. The findings demonstrate that various metabolic pathways, related to energy metabolism, macromolecular biosynthesis and redox signaling, are differentially modulated in asthma. Airway smooth muscle cell plays pivotal roles in asthma by contributing to airway hyperreactivity, inflammatory mediator release and remodeling. We posit that metabolomic profiling of airway structural cells, including airway smooth muscle cells, will shed light on molecular mechanisms of asthma and airway hyperresponsiveness and help identify novel therapeutic targets.

Adenosine Signaling in Mast Cells and Allergic Diseases

Adenosine is a nucleoside involved in the pathogenesis of allergic diseases. Its effects are mediated through its binding to G protein-coupled receptors: A1, A2a, A2b and A3. The receptors differ in the type of G protein they recruit, in the effect on adenylyl cyclase (AC) activity and the downstream signaling pathway triggered. Adenosine can produce both an enhancement and an inhibition of mast cell degranulation, indicating that adenosine effects on these receptors is controversial and remains to be clarified. Depending on the study model, A1, A2b, and A3 receptors have shown anti- or pro-inflammatory activity. However, most studies reported an anti-inflammatory activity of A2a receptor. The precise knowledge of the adenosine mechanism of action may allow to develop more efficient therapies for allergic diseases by using selective agonist and antagonist against specific receptor subtypes.

Application of Metabolomics in Pediatric Asthma: Prediction, Diagnosis and Personalized Treatment

Asthma in children remains a significant public health challenge affecting 5–20% of children in Europe and is associated with increased morbidity and societal healthcare costs. The high variation in asthma incidence among countries may be attributed to differences in genetic susceptibility and environmental factors. This respiratory disorder is described as a heterogeneous syndrome of multiple clinical manifestations (phenotypes) with varying degrees of severity and airway hyper-responsiveness, which is based on patient symptoms, lung function and response to pharmacotherapy. However, an accurate diagnosis is often difficult due to diversities in clinical presentation. Therefore, identifying early diagnostic biomarkers and improving the monitoring of airway dysfunction and inflammatory through non-invasive methods are key goals in successful pediatric asthma management. Given that asthma is caused by the interaction between genes and environmental factors, an emerging approach, metabolomics—the systematic analysis of small molecules—can provide more insight into asthma pathophysiological mechanisms, enable the identification of early biomarkers and targeted personalized therapies, thus reducing disease burden and societal cost. The purpose of this review is to present evidence on the utility of metabolomics in pediatric asthma through the analysis of intermediate metabolites of biochemical pathways that involve carbohydrates, amino acids, lipids, organic acids and nucleotides and discuss their potential application in clinical practice. Also, current challenges on the integration of metabolomics in pediatric asthma management and needed next steps are critically discussed.

Urine Microbe-Derived Extracellular Vesicles in Children With Asthma

PURPOSE

Several studies have found significant associations between asthma and microbiome. However, it is challenging to obtain-sputum and bronchoalveolar lavage samples from pediatric patients. Thus, we used voided urine to show that urine microbe-derived extracellular vesicles (EVs) in asthma are an available source for clinical research.

METHODS

Five urine samples were obtained at 2-3-month intervals from each patient with asthma (n = 20), and a single voided urine sample were obtained from each healthy child (n = 20). After isolating EVs, 16S rDNA pyrosequencing was performed. The Chao1 index and principal coordinate analysis (PCoA) were used to assess diversity. To predict microbiota functional capacities, Phylogenetic Investigation of Communities by Reconstruction of Unobserved States was used based on the Kyoto Encyclopedia of Genes and Genomes pathway database. Eight covariates were included in the EnvFit analysis to identify significant factors in the asthma group.

RESULTS

The asthma group showed lower Chao1 bacterial richness, and PCoA-based clustering differed significantly. Two phyla, and 13 families and genera were enriched or depleted. Functional profiling revealed significant differences between the asthma and control groups. EnvFit analysis of correlation to age, sex, body mass index, infection, season, asthma phenotype, severity, and symptoms was not significant except for infections associated with visit 1 and the season of visit 2.

CONCLUSIONS

This study showed that microbe-derived EVs were constantly altered in the urine of children with asthma, consistent with the findings of previous studies indicating microbiome changes in the lung and gut. The urine may reflect the specific pattern of microbiome EVs in children with asthma.

The Gut Microbiome and the Big Eight

Food allergies are increasing at an alarming rate, with 6.5% of the general population affected. It has been hypothesized that the increase in allergies stems from the “hygiene hypothesis”. The gut microbiome, a collection of microbiota and their genetic contents from the gastrointestinal tract, has been shown to play a part in the development of food allergies. The Food and Drug Administration requires all regulated food companies to clearly state an inclusion of the major, or “big eight” food allergens on packaging. This review is to provide information on the significant advancements related to the gut microbiome and each of the eight major food allergies individually. Establishment of causal connection between the microbiome and food allergies has uncovered novel mechanisms. New strategies are discussed to prevent future sensitization and reaction through novel treatments involving functional additives and dietary changes that target the microbiome.

Lipid metabolism and identification of biomarkers in asthma by lipidomic analysis

BACKGROUND

Lipids participate in many important biological functions through energy storage, material transport, signal transduction, and molecular recognition processes. Studies have reported that asthmatic patients have abnormal lipid metabolism. However, there are limited studies on the characterization of lipid metabolism in asthmatic patients by lipidomics.

METHODS

We characterized the plasma lipid profile of 28 healthy controls and 33 outpatients with asthma (18 mild, 15 moderate) by liquid chromatography mass spectrometry/mass spectrometry-based lipidomics.

RESULTS

We determined 1338 individual lipid species in the plasma. Significant changes were identified in ten lipid species in asthmatic patients than in healthy controls (all P < 0.05). Phosphatidylethanolamine (PE) (18:1p/22:6), PE (20:0/18:1), PE (38:1), sphingomyelin (SM) (d18:1/18:1), and triglyceride (TG) (16:0/16:0/18:1) positively correlated with the severity of asthma (all P < 0.05). Phosphatidylinositol (PI) (16:0/20:4), TG (17:0/18:1/18:1), phosphatidylglycerol (PG) (44:0), ceramide (Cer) (d16:0/27:2), and lysophosphatidylcholine (LPC) (22:4) negatively correlated with the severity of asthma (all P < 0.05). Correlation analysis showed a significant correlation between all ten lipid species (all P < 0.05). From the area under the curve of the receiver operating characteristic curve analysis, PE (38:1) was the major lipid metabolite that distinguished asthmatic patients from healthy controls, and may be considered a potential lipid biomarker. PE (20:0/18:1) and TG (16:0/16:0/18:1) might be related to IgE levels in asthmatic patients.

CONCLUSIONS

Our results indicated the presence of abnormal lipid metabolism, which correlated with the severity and IgE levels in asthmatic patients.

Breathomics in Asthmatic Children Treated with Inhaled Corticosteroids

BACKGROUND

"breathomics" enables indirect analysis of metabolic patterns underlying a respiratory disease. In this study, we analyze exhaled breath condensate (EBC) in asthmatic children before (T0) and after (T1) a three-week course of inhaled beclomethasone dipropionate (BDP).

METHODS

we recruited steroid-naive asthmatic children for whom inhaled steroids were indicated and healthy children, evaluating asthma control, spirometry and EBC (in asthmatics at T0 and T1). A liquid-chromatography-mass-spectrometry untargeted analysis was applied to EBC and a mass spectrometry-based target analysis to urine samples.

RESULTS

metabolomic analysis discriminated asthmatic (n = 26) from healthy children (n = 16) at T0 and T1, discovering 108 and 65 features relevant for the discrimination, respectively. Searching metabolomics databases, seven putative biomarkers with a plausible role in asthma biochemical-metabolic processes were found. After BDP treatment, asthmatic children, in the face of an improved asthma control (p < 0.001) and lung function (p = 0.01), showed neither changes in EBC metabolomic profile nor in urinary endogenous steroid profile.

CONCLUSIONS

"breathomics" can discriminate asthmatic from healthy children, with prostaglandin, fatty acid and glycerophospholipid as putative markers. The three-week course of BDP-in spite of a significant clinical improvement-was not associated with changes in EBC metabolic arrangement and urinary steroid profile.

Time-dependent metabolomics study of cerebral ischemia-reperfusion and its treatment: focus on the combination of traditional Chinese medicine and Western medicine

Cerebral ischemia is a common cerebrovascular disease with high mortality, and thrombolysis can cause more severe reperfusion injury. In clinical practice, Ginkgo biloba dispersible tablets combined with nimodipine have been widely used to reduce cerebral ischemia-reperfusion injury, but the mechanism has not been clearly elucidated. To explore this relationship, the change in metabolism between a sham operation group, a model group and an administration group was analyzed for the period after cerebral ischemia. Biochemical assays were used to assess injury extent and the therapeutic effects of different dosing regimens. A metabolomics method based on ultrahigh-performance liquid chromatography-quadrupole time-of-flight mass spectrometry was developed to screen biomarkers in plasma of rats and analyze abnormal metabolic pathways. Using statistical analysis, corticosterone, glutamine, oleic acid, isoleucine, phenylalanine and sphingomyelin (d18:1/16:0) were screened as diagnostic biomarkers. The metabolic pathways perturbed by cerebral ischemia-reperfusion involved phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine metabolism, alpha-linolenic acid metabolism, retinol metabolism, alanine, aspartate and glutamate metabolism, and glycerophospholipid metabolism. Analysis of the adjustment of biomarkers at different time points showed that the best time to evaluate the efficacy of combined administration is about 6 h after administration. Both pathological characteristics and metabolomics confirmed the better effect of the combined group than the individual groups. In this study, a non-targeted metabolomics method was developed to explore the mechanism of action of the combination of traditional Chinese and Western medicine in cerebral ischemia-reperfusion treatment, providing a theoretical basis for disease prognosis and treatment options. Graphical abstract.

Machine Learning-Empowered FTIR Spectroscopy Serum Analysis Stratifies Healthy, Allergic, and SIT-Treated Mice and Humans

The unabated global increase of allergic patients leads to an unmet need for rapid and inexpensive tools for the diagnosis of allergies and for monitoring the outcome of allergen-specific immunotherapy (SIT). In this proof-of-concept study, we investigated the potential of Fourier-Transform Infrared (FTIR) spectroscopy, a high-resolution and cost-efficient biophotonic method with high throughput capacities, to detect characteristic alterations in serum samples of healthy, allergic, and SIT-treated mice and humans. To this end, we used experimental models of ovalbumin (OVA)-induced allergic airway inflammation and allergen-specific tolerance induction in BALB/c mice. Serum collected before and at the end of the experiment was subjected to FTIR spectroscopy. As shown by our study, FTIR spectroscopy, combined with deep learning, can discriminate serum from healthy, allergic, and tolerized mice, which correlated with immunological data. Furthermore, to test the suitability of this biophotonic method for clinical diagnostics, serum samples from human patients were analyzed by FTIR spectroscopy. In line with the results from the mouse models, machine learning-assisted FTIR spectroscopy allowed to discriminate sera obtained from healthy, allergic, and SIT-treated humans, thereby demonstrating its potential for rapid diagnosis of allergy and clinical therapeutic monitoring of allergic patients.

Quantitative proteomics analysis of the treatment of asthma rats with total flavonoid extract from chamomile

OBJECTIVE

Asthma is a chronic immune disease that has become a serious public health problem. The currently available medications are not ideal because of their limitations and side effects; hence, new target proteins and signaling cascades for precise and safe therapy treatment are needed. This work established an ovalbumin-induced asthma rat model and treated it with total flavonoid extract from the Xinjiang chamomile. The proteins that were differentially expressed in the chamomile extract-treated asthmatic rats and the asthma and healthy rat groups were identified using isobaric tagging followed by LC-MS/MS. Kyoto encyclopedia of genes and genomes pathway analysis of the differentially expressed proteins was performed.

RESULTS

Pathways involved in purine metabolism, herpes simplex infection, and JNK phosphorylation and activation mediated by activated human TAK1 were enriched, indicating the intrinsic links between the mechanism of asthma development and treatment effects. Furthermore, we constructed a protein-protein interaction network and identified KIF3A as a potential target protein of chamomile extract that affected the Hedgehog signaling pathway.

CONCLUSIONS

This study may provide new insights into the pathogenesis of asthma and reveal several proteins and pathways that could be exploited to develop novel treatment approaches.

Four amino acids as serum biomarkers for anti-asthma effects in the ovalbumin-induced asthma mouse model treated with extract of Asparagus cochinchinensis

The butanol extract of Asparagus cochinchinensis roots fermented with Weissella cibaria (BAW) effectively prevents inflammation and remodeling of airway in the ovalbumin (OVA)-induced asthma model. To characterize biomarkers that can predict the anti-asthmatic effects induced by BAW treatment, we measured the alteration of endogenous metabolites in the serum of OVA-induced asthma mice after administration of low concentration BAW (BAWLo, 250 mg/kg) and high concentration BAW (BAWHi, 500 mg/kg) using ¹H nuclear magnetic resonance (¹H-NMR) spectral data. The number of immune cells and serum concentration of IgE as well as thickness of the respiratory epithelium and infiltration of inflammatory cells in the airway significantly recovered in the OVA+BAW treated group as compared to the OVA+Vehicle treated group. In the metabolic profile analysis, the pattern recognition showed completely separate clustering of serum analysis parameters between the OVA+Vehicle and OVA+BAW treated groups. Of the total endogenous metabolites, 19 metabolites were upregulated or downregulated in the OVA+Vehicle treated group as compared to the Control treated group. However, only 4 amino acids (alanine, glycine, methionine and tryptophan) were significantly recovered after BAWLo and BAWHi treatment. This study provides the first results pertaining to metabolic changes in the asthma model mice treated with OVA+BAW. Additionally, these findings show that 4 metabolites can be used as one of biomarkers to predict the anti-asthmatic effects.

Identification of multiple dysregulated metabolic pathways by GC-MS-based profiling of liver tissue in mice with OVA-induced asthma exposed to PM2.5

Particulate matter (PM) exposure increases the risk of asthma. However, the effect of PM_2.5 exposure on liver metabolism in mice with asthma symptoms remains unclear. We established an ovalbumin (OVA)-induced asthma model in mice and divided the animals into four groups: control group (C), PM_2.5 exposure group (P), OVA-induced asthma group (O) and OVA-induced asthma PM_2.5 exposure group (OP). Gas chromatography-mass spectrometry (GC-MS) was used to identify the metabolite markers and related perturbed metabolic pathways in mouse liver tissue after PM_2.5 exposure. Multivariate analysis showed 9 and 12 potential metabolite markers in the P and OP groups, respectively, after PM_2.5 exposure that were significantly correlated with lipid peroxidation indices. PM_2.5 exposure perturbed 5 and 7 metabolic pathways in the P and OP groups, respectively. These metabolic pathways mainly involve the lipid metabolism, amino acid metabolism, carbohydrate metabolism, and nucleotide metabolism. These results highlight the potential to study PM_2.5-triggered alterations via liver tissue in normal and OVA-induced asthmatic mice to gain a more realistic appraisal of the resulting early toxicity events. Additionally, these results revealed potential metabolite markers of early antioxidant defense events triggered by PM_2.5 and indicated that metabolite markers are more sensitive than antioxidant indicators.

Plasma based targeted metabolomic analysis reveals alterations of phosphatidylcholines and oxidative stress markers in guinea pig model of allergic asthma

Bronchial asthma is one of the most common, chronic respiratory diseases, characterized by reversible airway obstruction, eosinophil and Th2 infiltration, airway hyperresponsiveness and airway remodelling; with many cells and mediators involved. Metabolomics is a relatively new field in "omics" sciences enabling the identification of metabolome for better diagnostics and studying of diseases phenotype. The aim of this study was to investigate the role of targeted metabolomics study for better understanding of the bronchial asthma pathophysiology and finding potential biomarkers in experimental models of eosinophilic inflammation. Plasma level of 185 metabolites was measured with the AbsoluteIDQ™ p180 kit in guinea pigs with experimentally-induced allergic inflammation (n = 15) compared to naïve non-sensitised and non-challenged controls (n = 18). Of the 185 metabolites identified in plasma, 22 were significantly different and changed in ovalbumin sensitised animals. Plasma level of 13 phosphatidylcholines with saturated and unsaturated long-chain fatty acids, total phosphatidylcholines count, carnitine, symmetric dimethylarginine and its ratio to total unmodified arginine, and kynurenine to tryptophan ratio were found to be decreased, while phospholipase A2 activity indicator, tryptophan, taurine and ratio of methionine sulfoxide to unmodified methionine were found to be increased in sensitised guinea pigs compared to naïve controls. Targeted metabolomic analysis revealed significant differences in plasma metabolome of sensitised guinea pigs. Our observations point to the activation of inflammatory and immune pathways, as well as the involvement of oxidative stress.

Toxicogenomic analysis of publicly available transcriptomic data can predict food, drugs, and chemical-induced asthma

Background

: With the increasing incidence of asthma, more attention is focused on the diverse and complex nutritional and environmental triggers of asthma exacerbations. Currently, there are no established risk assessment tools to evaluate asthma triggering potentials of most of the nutritional and environmental triggers encountered by asthmatic patients.

Purpose

 The objective of this study is to devise a reliable workflow, capable of estimating the toxicogenomic effect of such factors on key player genes in asthma pathogenesis.

Methods

Gene expression extracted from publicly available datasets of asthmatic bronchial epithelium were subjected to a comprehensive analysis of differential gene expression to identify significant genes involved in asthma development and progression. The identified genes were subjected to Gene Set Enrichment Analysis using a total of 31,826 gene sets related to chemical, toxins, and drugs to identify common agents that share similar asthma-related targets genes and signaling pathways.

Results

Our analysis identified 225 differentially expressed genes between severe asthmatic and healthy bronchial epithelium. Gene Set Enrichment Analysis of the identified genes showed that they are involved in response to toxic substances and organic cyclic compounds and are targeted by 41 specific diets, plants products, and plants related toxins (eg adenine, arachidonic acid, baicalein, caffeic acid, corilagin, curcumin, ellagic acid, luteolin, microcystin-RR, phytoestrogens, protoporphyrin IX, purpurogallin, rottlerin, and salazinic acid). Moreover, the identified chemicals share interesting inflammation-related pathways like NF-κB.

Conclusion

Our analysis was able to explain and predict the toxicity in terms of stimulating the differentially expressed genes between severe asthmatic and healthy epithelium. Such an approach can pave the way to generate a cost-effective and reliable source for asthma-specific toxigenic reports thus allowing the asthmatic patients, physicians, and medical researchers to be aware of the potential triggering factors with fatal consequences.

Identification of multiple dysregulated metabolic pathways by GC-MS-based profiling of lung tissue in mice with PM2.5-induced asthma

The risk of development of asthma, a multi-faceted chronic disease, increases as a result of exposure to PM_2.5. However, the mechanism underlying asthma-related metabolic changes caused by PM_2.5 exposure is unclear. Here, we investigated the major metabolic changes, metabolic pathways involved, and underlying molecular mechanisms in mice with PM_2.5 exposure-induced asthma. Forty-eight adult female mice were randomly assigned to control (C), low concentration-PM_2.5 exposure: 0.50 mg kg^-1 (L), medium concentration-PM_2.5 exposure: 1.58 mg kg^-1 (M), and high concentration-PM_2.5 exposure: 4.98 mg kg^-1 (H) groups. M and H groups presented significantly higher IL-4, IL-8, IL-1β, IL-5, IL-13, and OVA-specific IgE levels, and significantly lower IFN-γ levels, than the C group, as well as significantly increased eosinophil count and MUC5AC expression in the lung tissue. These findings indicate that exposure to medium and high concentrations of PM_2.5 induced asthma in mice. Statistical analyses identified 13 asthma-related major metabolites, which were analyzed by gas chromatography-mass spectrometry (GC-MS). Meta Mapp Software revealed 4 major metabolic pathways. PM_2.5-induced ATP requirement and oxidative stress may perturb metabolic processes in asthma. The present findings increase our understanding of the toxic effect of PM_2.5 in the development of asthma and identify potentially useful biomarkers.

Altered metabolites in guinea pigs with allergic asthma after acupoint sticking therapy: New insights from a metabolomics approach

BACKGROUND

Clinical evidence gathered in Chinese communities suggested that acupoint sticking therapy could be an alternative treatment for asthma-related diseases. However, its underlying mechanism is still poorly understood.

AIM/HYPOTHESIS

In this study, we aimed to investigate the mechanism of the anti-inflammatory effect of acupoint sticking application with 'Treatment of Winter Disease in Summer' (TWDS) prescription by using metabolomics.

METHODS

Allergic asthma in guinea pig was sensitized and challenged by ovalbumin (OVA). Histopathological evaluation of the lung tissue was performed by hematoxylin and eosin (H&E) staining and Masson's trichrome staining. The levels of Th2 cytokine and IgE level in serum were measured using enzyme-linked immunoassay (ELISA). The mRNA expression levels of IL-4, IL-5, IL-13 and orosomucoid-like 3 (ORMDL3) were measured using quantitative reverse transcription polymerase chain reaction (RT-qPCR). Proteins of NF-κB signaling pathway were measured using western blot. The serum metabolomics profiles were obtained by using ultra-performance liquid chromatography combined with electrospray ionization quadrupole time-of-flight mass spectrometry (UPLC-ESI-QTOF-MS).

RESULTS

The overall results confirmed that AST with TWDS prescription had a significant protective effect against OVA-induced allergic asthma in guinea pig. This treatment not only attenuated airway inflammation and collagen deposition in the airway, but also decreased the levels of IL-4, IL-5, IL-13 and IgE in serum. In addition, metabolomics results indicated that metabolisms of phospholipid, sphingolipid, purine, amino acid and level of epinephrine were restored back to the normal control level. Moreover, results of the gene expression of ORMDL3 in lung tissues indicated that AST using TWDS could alter the sphingolipid metabolism. Further western blotting analysis also showed that its anti-inflammatory mechanism was by decreasing the phosphorylation of p65 and IκB.

CONCLUSION

The study demonstrated that metabolomics provides a better understanding of the actions of TWDS acupoint sticking therapy on OVA-induced allergic asthma.

Obesity-Associated Metabolic Signatures Correlate to Clinical and Inflammatory Profiles of Asthma: A Pilot Study

PURPOSE

Obesity is associated with metabolic dysregulation, but the underlying metabolic signatures involving clinical and inflammatory profiles of obese asthma are largely unexplored. We aimed at identifying the metabolic signatures of obese asthma.

METHODS

Eligible subjects with obese (n = 11) and lean (n = 22) asthma underwent body composition and clinical assessment, sputum induction, and blood sampling. Sputum supernatant was assessed for interleukin (IL)-1β, -4, -5, -6, -13, and tumor necrosis factor (TNF)-α, and serum was detected for leptin, adiponectin and C-reactive protein. Untargeted gas chromatography time-of-flight mass spectrometry (GC-TOF-MS)-based metabolic profiles in sputum, serum and peripheral blood monocular cells (PBMCs) were analyzed by orthogonal projections to latent structures-discriminate analysis (OPLS-DA) and pathway topology enrichment analysis. The differential metabolites were further validated by correlation analysis with body composition, and clinical and inflammatory profiles.

RESULTS

Body composition, asthma control, and the levels of IL-1β, -4, -13, leptin and adiponectin in obese asthmatics were significantly different from those in lean asthmatics. OPLS-DA analysis revealed 28 differential metabolites that distinguished obese from lean asthmatic subjects. The validation analysis identified 18 potential metabolic signatures (11 in sputum, 4 in serum and 2 in PBMCs) of obese asthmatics. Pathway topology enrichment analysis revealed that cyanoamino acid metabolism, caffeine metabolism, alanine, aspartate and glutamate metabolism, phenylalanine, tyrosine and tryptophan biosynthesis, pentose phosphate pathway in sputum, and glyoxylate and dicarboxylate metabolism, glycerolipid metabolism and pentose phosphate pathway in serum are suggested to be significant pathways related to obese asthma.

CONCLUSIONS

GC-TOF-MS-based metabolomics indicates obese asthma is characterized by a metabolic profile different from lean asthma. The potential metabolic signatures indicated novel immune-metabolic mechanisms in obese asthma with providing more phenotypic and therapeutic implications, which needs further replication and validation.

Serum Metabolomics Analysis of Asthma in Different Inflammatory Phenotypes: A Cross-Sectional Study in Northeast China

BACKGROUND AND OBJECTIVE

Asthma as a chronic heterogeneous disease seriously affects the quality of life. Incorrect identification for its clinical phenotypes lead to a huge waste of medical resources. Metabolomic technique as a novel approach to explore the pathogenesis of diseases have not been used to study asthma based on their clear defined inflammatory phenotypes. This study is aimed to distinguish the divergent metabolic profile in different asthma phenotypes and clarify the pathogenesis of them.

METHODS

Participants including eosinophilic asthmatics (EA, n=13), noneosinophilic asthmatics (NEA, n=16), and healthy controls (HC, n=15) were enrolled. A global profile of untargeted serum metabolomics was identified with Ultra Performance Liquid Chromatography-Mass Spectrometry technique.

RESULTS

Multivariate analysis was performed and showed a clear distinction between EA, NEA, and HC. A total of 18 different metabolites were recognized between the three groups based on OPLS-DA model and involved in 10 perturbed metabolic pathways. Glycerophospholipid metabolism, retinol metabolism, and sphingolipid metabolism were identified as the most significant changed three pathways (impact > 0.1 and -log(P) > 4) between the phenotypes.

CONCLUSIONS

We showed that the different inflammatory phenotypes of asthma involve the immune regulation, energy, and nutrients metabolism. The clarified metabolic profile contributes to understanding the pathophysiology of asthma phenotypes and optimizing the therapeutic strategy against asthma heterogeneity.

Metabolomics in asthma: where do we stand?

PURPOSE OF REVIEW

Metabolomics has been used to uncover the metabolic signatures of asthma, both for biomarker identification and pathophysiologic mechanisms research. We aimed to review recent advances in this field, published since 2016, and discuss these findings implications to future research and application into clinical practice.

RECENT FINDINGS

Experimental asthma models and clinical studies in both children and adults supported independent metabolic signatures of asthma. Common reported pathways included purine, glycerophospholipid, glutathione, fatty acids, and arginine and proline metabolism. Metabolomics-based studies identified candidate biomarkers related to asthma severity and corticosteroid resistance, and supported the definition of the obesity-related phenotype at the molecular level. A systematic review with meta-analysis and recent prospective studies favored exhaled volatile organic compounds as one of the most promising biomarkers in asthma diagnosis and monitoring.

SUMMARY

Metabolomics has provided unique and novel insights into asthma profiling at the molecular level. Current challenges include procedures standardization and control of potentially confounding variables for external validation. Point-of-care technology developments bring metabolomics closer to clinical practice. In addition to biomarkers identification, relating metabolites to their biologic role will serve as critical foundations for understanding the biology underpinning asthma heterogeneity and for specific-targeted therapies. VIDEO ABSTRACT.

Plasma metabolite profiles in children with current asthma

BACKGROUND

Identifying metabolomic profiles of children with asthma has the potential to increase understanding of asthma pathophysiology.

OBJECTIVE

To identify differences in plasma metabolites between children with and without current asthma at mid-childhood.

METHODS

We used untargeted mass spectrometry to measure plasma metabolites in 237 children (46 current asthma cases and 191 controls) in Project Viva, a birth cohort from eastern Massachusetts, USA. Current asthma was assessed at mid-childhood (mean age 8.0 years). The ability of a broad spectrum metabolic profile to distinguish between cases and controls was assessed using partial least squares discriminant analysis. We used logistic regression models to identify individual metabolites that were differentially abundant by case-control status. We tested significant metabolites for replication in 411 children from the VDAART clinical trial.

RESULTS

There was no evidence of a systematic difference in the metabolome of children reporting current asthma vs. healthy controls according to partial least squares discriminant analysis. However, several metabolites were associated with odds of current asthma at a nominally significant threshold (P < .05), including a metabolite of nicotinamide (N1-Methyl-2-pyridone-5-carboxamide (Odds Ratio (OR) = 2.8 (95% CI 1.1-8.0)), a pyrimidine metabolite (5,6-dihydrothymine (OR = 0.4 (95% CI 0.2-0.9)), bile constituents (biliverdin (OR = 0.4 (95%CI 0.1-0.9), taurocholate (OR = 2.0 (95% CI 1.2-3.4)), two peptides likely derived from fibrinopeptide A (ORs from 1.6 to 1.7), and a gut microbiome metabolite (p-cresol sulphate OR = 0.5 (95% CI 0.2-0.9)). The associations for N1-Methyl-2-pyridone-5-carboxamide and p-cresol sulphate replicated in the independent VDAART population (one-sided P values = .03-.04).

CONCLUSIONS AND CLINICAL RELEVANCE

Current asthma is nominally associated with altered levels of several metabolites, including metabolites in the nicotinamide pathway, and a bacterial metabolite derived from the gut microbiome.

Toll-Like Receptor 7/8 Ligand, S28463, Suppresses Ascaris suum-induced Allergic Asthma in Nonhuman Primates

S28463 (S28), a ligand for Toll-like receptor 7/8, has been shown to have antiinflammatory properties in rodent models of allergic asthma. The principle goal of this study was to assess whether these antiinflammatory effects can also be observed in a nonhuman primate (NHP) model of allergic asthma. NHPs were sensitized then challenged with natural allergen, Ascaris suum extract. The animals were treated with S28 orally before each allergen challenge. The protective effect of S28 in NHPs was assessed by measuring various asthma-related phenotypes. We also characterized the metabolomic and proteomic signatures of the lung environment and plasma to identify markers associated with the disease and treatment. Our data demonstrate that clinically relevant parameters, such as wheal and flare response, blood IgE levels, recruitment of white blood cells to the bronchoalveolar space, and lung responsiveness, are decreased in the S28-treated allergic NHPs compared with nontreated allergic NHPs. Furthermore, we also identified markers that can distinguish allergic from nonallergic or allergic and drug-treated NHPs, such as metabolites, phosphocreatine and glutathione, in the plasma and BAL fluid, respectively; and inflammatory cytokines, IL-5 and IL-13, in the bronchoalveolar lavage fluid. Our preclinical study demonstrates that S28 has potential as a treatment for allergic asthma in primate species closely related to humans. Combined with our previous findings, we demonstrate that S28 is effective in different models of asthma and in different species, and has the antiinflammatory properties clinically relevant for the treatment of allergic asthma.

Allergic asthma: an overview of metabolomic strategies leading to the identification of biomarkers in the field

Allergic asthma is a prominent disease especially during childhood. Indoor allergens, in general, and particularly house dust mites (HDM) are the most prevalent sensitizers associated with allergic asthma. Available data show that 65-130 million people are mite-sensitized world-wide and as many as 50% of these are asthmatic. In fact, sensitization to HDM in the first years of life can produce devastating effects on pulmonary function leading to asthmatic syndromes that can be fatal. To date, there has been considerable research into the pathological pathways and structural changes associated with allergic asthma. However, limitations related to the disease heterogeneity and a lack of knowledge into its pathophysiology have impeded the generation of valuable data needed to appropriately phenotype patients and, subsequently, treat this disease. Here, we report a systematic and integral analysis of the disease, from airway remodelling to the immune response taking place throughout the disease stages. We present an overview of metabolomics, the management of complex multifactorial diseases through the analysis of all possible metabolites in a biological sample, obtaining a global interpretation of biological systems. Special interest is placed on the challenges to obtain biological samples and the methodological aspects to acquire relevant information, focusing on the identification of novel biomarkers associated with specific phenotypes of allergic asthma. We also present an overview of the metabolites cited in the literature, which have been related to inflammation and immune response in asthma and other allergy-related diseases.

Dysregulation of metabolic pathways in a mouse model of allergic asthma

BACKGROUND

Asthma is a complex lung disease resulting from the interplay of genetic and environmental factors. To understand the molecular changes that occur during the development of allergic asthma without genetic and environmental confounders, an experimental model of allergic asthma in mice was used. Our goals were to (1) identify changes at the small molecule level due to allergen exposure, (2) determine perturbed pathways due to disease, and (3) determine whether small molecule changes correlate with lung function.

METHODS

In this experimental model of allergic asthma, matched bronchoalveolar lavage (BAL) fluid and plasma were collected from three groups of C57BL6 mice (control vs sensitized and/or challenged with ovalbumin, n=3-5/group) 6 hour, 24 hour, and 48 hour after the last challenge. Samples were analyzed using liquid chromatography-mass spectrometry-based metabolomics. Airway hyper-responsiveness (AHR) measurements and differential cell counts were performed.

RESULTS

In total, 398 and 368 dysregulated metabolites in the BAL fluid and plasma of sensitized and challenged mice were identified, respectively. These belonged to four, interconnected pathways relevant to asthma pathogenesis: sphingolipid metabolism (P=6.6×10^-5 ), arginine and proline metabolism (P=1.12×10^-7 ), glycerophospholipid metabolism (P=1.3×10^-10 ), and the neurotrophin signaling pathway (P=7.0×10^-6 ). Furthermore, within the arginine and proline metabolism pathway, a positive correlation between urea-1-carboxylate and AHR was observed in plasma metabolites, while ornithine revealed a reciprocal effect. In addition, agmatine positively correlated with lung eosinophilia.

CONCLUSION

These findings point to potential targets and pathways that may be central to asthma pathogenesis and can serve as novel therapeutic targets.

Tuning Metabolome Coverage in Reversed Phase LC-MS Metabolomics of MeOH Extracted Samples Using the Reconstitution Solvent Composition

Considering the physicochemical diversity of the metabolome, untargeted metabolomics will inevitably discriminate against certain compound classes. Efforts are nevertheless made to maximize the metabolome coverage. Contrary to the main steps of a typical liquid chromatography-mass spectrometry (LC-MS) metabolomics workflow, such as metabolite extraction, the sample reconstitution step has not been optimized for maximal metabolome coverage. This sample concentration step typically occurs after metabolite extraction, when dried samples are reconstituted in a solvent for injection on column. The aim of this study was to evaluate the impact of the sample reconstitution solvent composition on metabolome coverage in untargeted LC-MS metabolomics. Lysogeny Broth medium samples reconstituted in MeOH/H₂O ratios ranging from 0 to 100% MeOH and analyzed with untargeted reversed phase LC-MS showed that the highest number of metabolite features (n = 1500) was detected in samples reconstituted in 100% H₂O. As compared to a commonly used reconstitution solvent mixture of 50/50 MeOH/H₂O, our results indicate that the small fraction of compounds increasing in peak area response by the addition of MeOH to H₂O, 5%, is outweighed by the fraction of compounds with decreased response, 57%. We evaluated our results on human serum samples from lymphoma patients and healthy control subjects. Reconstitution in 100% H₂O resulted in a higher number of significant metabolites discriminating between these two groups than both 50% and 100% MeOH. These findings show that the sample reconstitution step has a clear impact on the metabolome coverage of MeOH extracted biological samples, highlighting the importance of the reconstitution solvent composition for untargeted discovery metabolomics.

Urinary and Fecal Metabonomics Study of the Protective Effect of Chaihu-Shu-Gan-San on Antibiotic-Induced Gut Microbiota Dysbiosis in Rats

Accumulating evidence suggests that the gut microbiota dysbiosis and their host metabolic phenotype alteration is an important factor in human disease development. A traditional Chinese herbal formula, Chaihu-Shu-Gan-San (CSGS), has been effectively used in the treatment of various gastrointestinal (GI) disorders. The present study was carried out to investigate whether CSGS modulates the host metabolic phenotype under the condition of gut microbiota dysbiosis. The metabonomics studies of biochemical changes in urine and feces of antibiotic-induced gut microbiota dysbiosis rats after treatment with CSGS were performed using UPLC-Q-TOF/MS. Partial least squares-discriminate analysis (PLS-DA) indicated that the CSGS treatment reduced the metabolic phenotype perturbation induced by antibiotic. In addition, there was a strong correlation between gut microbiota genera and urinary and fecal metabolites. Moreover, the correlation analysis and the metabolic pathway analysis (MetPA) identified that three key metabolic pathways including glycine, serine and threonine metabolism, nicotinate and nicotinamide metabolism, and bile acid metabolism were the most relevant pathways involved in antibiotic-induced gut microbiota dysbiosis. These findings provided a comprehensive understanding of the protective effects of CSGS on the host metabolic phenotype of the gut microbiota dysbiosis rats, and further as a new source for drug leads in gut microbiota-targeted disease management.

Determining the presence of asthma-related molecules and salivary contamination in exhaled breath condensate

Background

Researchers investigating lung diseases, such as asthma, have questioned whether certain compounds previously reported in exhaled breath condensate (EBC) originate from saliva contamination. Moreover, despite its increasing use in ‘omics profiling studies, the constituents of EBC remain largely uncharacterized. The present study aims to define the usefulness of EBC in investigating lung disease by comparing EBC, saliva, and saliva-contaminated EBC using targeted and untargeted mass spectrometry and the potential of metabolite loss from adsorption to EBC sample collection tubes.

Methods

Liquid chromatography mass spectrometry (LC-MS) was used to analyze samples from 133 individuals from three different cohorts. Levels of amino acids and eicosanoids, two classes of molecules previously reported in EBC and saliva, were measured using targeted LC-MS. Cohort 1 was used to examine contamination of EBC by saliva. Samples from Cohort 1 consisted of clean EBC, saliva-contaminated EBC, and clean saliva from 13 healthy volunteers; samples were analyzed using untargeted LC-MS. Cohort 2 was used to compare eicosanoid levels from matched EBC and saliva collected from 107 asthmatic subjects. Samples were analyzed using both targeted and untargeted LC-MS. Cohort 3 samples consisted of clean-EBC collected from 13 subjects, including smokers and non-smokers, and were used to independently confirm findings; samples were analyzed using targeted LC-MS, untargeted LC-MS, and proteomics. In addition to human samples, an in-house developed nebulizing system was used to determine the potential for EBC samples to be contaminated by saliva.

Results

Out of the 400 metabolites detected in both EBC and saliva, 77 were specific to EBC; however, EBC samples were concentrated 20-fold to achieve this level of sensitivity. Amino acid concentrations ranged from 196 pg/mL – 4 μg/mL (clean EBC), 1.98 ng/mL – 6 μg/mL (saliva-contaminated EBC), and 13.84 ng/mL – 1256 mg/mL (saliva). Eicosanoid concentration ranges were an order of magnitude lower; 10 pg/mL – 76.5 ng/mL (clean EBC), 10 pg/mL – 898 ng/mL (saliva-contaminated EBC), and 2.54 ng/mL – 272.9 mg/mL (saliva). Although the sample size of the replication cohort (Cohort 3) did not allow for statistical comparisons, two proteins and 19 eicosanoids were detected in smoker vs. non-smoker clean-EBC.

Conclusions

We conclude that metabolites are present and detectable in EBC using LC-MS; however, a large starting volume of sample is required.

Electronic supplementary material

The online version of this article (doi:10.1186/s12931-017-0538-5) contains supplementary material, which is available to authorized users.

The Effect of Chinese Herbal Medicine Formula mKG on Allergic Asthma by Regulating Lung and Plasma Metabolic Alternations

Asthma is a chronic inflammatory disorder of the airway and is characterized by airway remodeling, hyperresponsiveness, and shortness of breath. Modified Kushen Gancao Formula (mKG), derived from traditional Chinese herbal medicines (TCM), has been demonstrated to have good therapeutic effects on experimental allergic asthma. However, its anti-asthma mechanism remains currently unknown. In the present work, metabolomics studies of biochemical changes in the lung tissue and plasma of ovalbumin (OVA)-induced allergic asthma mice with mKG treatment were performed using ultra high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (UPLC-Q-TOF/MS). Partial least squares–discriminate analysis (PLS−DA) indicated that the metabolic perturbation induced by OVA was reduced after mKG treatment. A total of twenty-four metabolites involved in seven metabolic pathways were identified as potential biomarkers in the development of allergic asthma. Among them, myristic acid (L3 or P2), sphinganine (L6 or P4), and lysoPC(15:0) (L12 or P16) were detected both in lung tissue and plasma. Additionally, l-acetylcarnitine (L1), thromboxane B2 (L2), 10-HDoHE (L10), and 5-HETE (L11) were first reported to be potential biomarkers associated with allergic asthma. The treatment of mKG mediated all of those potential biomarkers except lysoPC(15:0) (P16). The anti-asthma mechanism of mKG can be achieved through the comprehensive regulation of multiple perturbed biomarkers and metabolic pathways.

Variations in gut microbiota and fecal metabolic phenotype associated with depression by 16S rRNA gene sequencing and LC/MS-based metabolomics

As a prevalent, life-threatening and highly recurrent psychiatric illness, depression is characterized by a wide range of pathological changes; however, its etiology remains incompletely understood. Accumulating evidence supports that gut microbiota affects not only gastrointestinal physiology but also central nervous system (CNS) function and behavior through the microbiota-gut-brain axis. To assess the impact of gut microbiota on fecal metabolic phenotype in depressive conditions, an integrated approach of 16S rRNA gene sequencing combined with ultra high-performance liquid chromatography-mass spectrometry (UHPLC-MS) based metabolomics was performed in chronic variable stress (CVS)-induced depression rat model. Interestingly, depression led to significant gut microbiota changes, at the phylum and genus levels in rats treated with CVS compared to controls. The relative abundances of the bacterial genera Marvinbryantia, Corynebacterium, Psychrobacter, Christensenella, Lactobacillus, Peptostreptococcaceae incertae sedis, Anaerovorax, Clostridiales incertae sedis and Coprococcus were significantly decreased, whereas Candidatus Arthromitus and Oscillibacter were markedly increased in model rats compared with normal controls. Meanwhile, distinct changes in fecal metabolic phenotype of depressive rats were also found, including lower levels of amino acids, and fatty acids, and higher amounts of bile acids, hypoxanthine and stercobilins. Moreover, there were substantial associations of perturbed gut microbiota genera with the altered fecal metabolites, especially compounds involved in the metabolism of tryptophan and bile acids. These results showed that the gut microbiota was altered in association with fecal metabolism in depressive conditions. These findings suggest that the 16S rRNA gene sequencing and LC-MS based metabolomics approach can be further applied to assess pathogenesis of depression.

Distinct Metabolic Profile of Inhaled Budesonide and Salbutamol in Asthmatic Children during Acute Exacerbation

Inhaled budesonide and salbutamol represent the most important and frequently used drugs in asthmatic children during acute exacerbation. However, there is still no consensus about their resulting metabolic derangements; thus, this study was conducted to determine the distinct metabolic profiles of these two drugs. A total of 69 children with asthma during acute exacerbation were included, and their serum and urine were investigated using high-resolution nuclear magnetic resonance (NMR). A metabolomics analysis was performed using a principal component analysis and orthogonal signal correction-partial least squares using SIMCA-P. The different metabolites were identified, and the distinct metabolic profiles were analysed using MetPA. A high-resolution NMR-based serum and urine metabolomics approach was established to study the overall metabolic changes after inhaled budesonide and salbutamol in asthmatic children during acute exacerbation. The perturbed metabolites included 22 different metabolites in the serum and 21 metabolites in the urine. Based on an integrated analysis, the changed metabolites included the following: increased 4-hydroxybutyrate, lactate, cis-aconitate, 5-hydroxyindoleacetate, taurine, trans-4-hydroxy-l-proline, tiglylglycine, 3-hydroxybutyrate, 3-methylhistidine, glucose, cis-aconitate, 2-deoxyinosine and 2-aminoadipate; and decreased alanine, glycerol, arginine, glycylproline, 2-hydroxy-3-methylvalerate, creatine, citrulline, glutamate, asparagine, 2-hydroxyvalerate, citrate, homoserine, histamine, sn-glycero-3-phosphocholine, sarcosine, ornithine, creatinine, glycine, isoleucine and trimethylamine N-oxide. The MetPA analysis revealed seven involved metabolic pathways: arginine and proline metabolism; taurine and hypotaurine metabolism; glycine, serine and threonine metabolism; glyoxylate and dicarboxylate metabolism; methane metabolism; citrate cycle; and pyruvate metabolism. The perturbed metabolic profiles suggest potential metabolic reprogramming associated with a combination treatment of inhaled budesonide and salbutamol in asthmatic children.