Linoleic acid metabolite drives severe asthma by causing airway epithelial injury. Sci Rep. 2013;3:1349. [PMID: 23443229 PMCID: PMC3583002 DOI: 10.1038/srep01349]

Investigating the Catalytic Site of Human 15-Lipoxygenase-1 via Marine Natural Products

Human 15-lipoxygenase-1 (15-LOX-1) is a key enzyme that possesses an important role in (neuro)inflammatory diseases. The pocket of the enzyme plays the role of a chiral catalyst, and therefore chirality could be an important component for the design of effective enzyme inhibitors. To advance our knowledge on this concept, we developed a library of the identified chiral 15-LOX-1 inhibitors and applied cheminformatic tools. Our analysis highlighted specific structural elements, which we integrated them in small molecules, and employed them as "smart" tools to effectively navigate the chemical space of previously unexplored regions. To this purpose, we utilized the marine derived natural product phosphoeleganin (PE) among with a small library of synthetic fragment derivatives, including a certain degree of stereochemical diversity. Enzyme inhibition/kinetic and molecular modelling studies has been performed in order to characterize structurally novel PE-based inhibitors, which proved to present a different type of inhibition with low micromolar potency, according to their structural features. We demonstrate that different warheads work as anchor, and either guide specific stereochemistry, or causing a time-depended inhibition. Finally, we prove that the positioning of the chiral substituents or/and the favorable stereochemistry can be crucial, as it can lead from active to completely inactive compounds.

Heavy Metal Exposure-Mediated Dysregulation of Sphingolipid Metabolism

Exposure to heavy metals (HMs) is often associated with inflammation and cell death, exacerbating respiratory diseases including asthma. Most inhaled particulate HM exposures result in the deposition of HM-bound fine particulate matter, PM2.5, in pulmonary cell populations. While localized high concentrations of HMs may be a causative factor, existing studies have mostly evaluated the effects of systemic or low-dose chronic HM exposures. This report investigates the impact of local high concentrations of specific HMs (NaAsO2, MnCl2, and CdCl2) on sphingolipid homeostasis and oxidative stress, as both play a role in mediating responses to HM exposure and have been implicated in asthma. Utilizing an in vitro model system and three-dimensional ex vivo human tissue models, we evaluated the expression of enzymatic regulators of the salvage, recycling, and de novo synthesis pathways of sphingolipid metabolism, and observed differential modulation in these enzymes between HM exposures. Sphingolipidomic analyses of specific HM-exposed cells showed increased levels of anti-apoptotic sphingolipids and reduced pro-apoptotic sphingolipids, suggesting activation of the salvage and de novo synthesis pathways. Differential sphingolipid regulation was observed within HM-exposed lung tissues, with CdCl2 exposure and NaAsO2 exposure activating the salvage and de novo synthesis pathway, respectively. Additionally, using spatial transcriptomics and quantitative real-time PCR, we identified HM exposure-induced transcriptomic signatures of oxidative stress in epithelial cells and human lung tissues.

TRPV1 nociceptors are required to optimize antigen-specific primary antibody responses to novel antigens

BACKGROUND

Key to the advancement of the field of bioelectronic medicine is the identification of novel pathways of neural regulation of immune function. Sensory neurons (termed nociceptors) recognize harmful stimuli and initiate a protective response by eliciting pain and defensive behavior. Nociceptors also interact with immune cells to regulate host defense and inflammatory responses. However, it is still unclear whether nociceptors participate in regulating primary IgG antibody responses to novel antigens.

METHODS

To understand the role of transient receptor potential vanilloid 1 (TRPV1)-expressing neurons in IgG responses, we generated TRPV1-Cre/Rosa-ChannelRhodopsin2 mice for precise optogenetic activation of TRPV1 + neurons and TRPV1-Cre/Lox-diphtheria toxin A mice for targeted ablation of TRPV1-expressing neurons. Antigen-specific antibody responses were longitudinally monitored for 28 days.

RESULTS

Here we show that TRPV1 expressing neurons are required to develop an antigen-specific immune response. We demonstrate that selective optogenetic stimulation of TRPV1+ nociceptors during immunization significantly enhances primary IgG antibody responses to novel antigens. Further, mice rendered deficient in TRPV1- expressing nociceptors fail to develop primary IgG antibody responses to keyhole limpet hemocyanin or haptenated antigen.

CONCLUSION

This functional and genetic evidence indicates a critical role for nociceptor TRPV1 in antigen-specific primary antibody responses to novel antigens. These results also support consideration of potential therapeutic manipulation of nociceptor pathways using bioelectronic devices to enhance immune responses to foreign antigens.

Murine Alox8 versus the human ALOX15B ortholog: differences and similarities

Human arachidonate 15-lipoxygenase type B is a lipoxygenase that catalyzes the peroxidation of arachidonic acid at carbon-15. The corresponding murine ortholog however has 8-lipoxygenase activity. Both enzymes oxygenate polyunsaturated fatty acids in S-chirality with singular reaction specificity, although they generate a different product pattern. Furthermore, while both enzymes utilize both esterified fatty acids and fatty acid hydro(pero)xides as substrates, they differ with respect to the orientation of the fatty acid in their substrate-binding pocket. While ALOX15B accepts the fatty acid "tail-first," Alox8 oxygenates the free fatty acid with its "head-first." These differences in substrate orientation and thus in regio- and stereospecificity are thought to be determined by distinct amino acid residues. Towards their biological function, both enzymes share a commonality in regulating cholesterol homeostasis in macrophages, and Alox8 knockdown is associated with reduced atherosclerosis in mice. Additional roles have been linked to lung inflammation along with tumor suppressor activity. This review focuses on the current knowledge of the enzymatic activity of human ALOX15B and murine Alox8, along with their association with diseases.

Evidence for vagal sensory neural involvement in influenza pathogenesis and disease

Influenza A virus (IAV) is a common respiratory pathogen and a global cause of significant and often severe morbidity. Although inflammatory immune responses to IAV infections are well described, little is known about how neuroimmune processes contribute to IAV pathogenesis. In the present study, we employed surgical, genetic, and pharmacological approaches to manipulate pulmonary vagal sensory neuron innervation and activity in the lungs to explore potential crosstalk between pulmonary sensory neurons and immune processes. Intranasal inoculation of mice with H1N1 strains of IAV resulted in stereotypical antiviral lung inflammation and tissue pathology, changes in breathing, loss of body weight and other clinical signs of severe IAV disease. Unilateral cervical vagotomy and genetic ablation of pulmonary vagal sensory neurons had a moderate effect on the pulmonary inflammation induced by IAV infection, but significantly worsened clinical disease presentation. Inhibition of pulmonary vagal sensory neuron activity via inhalation of the charged sodium channel blocker, QX-314, resulted in a moderate decrease in lung pathology, but again this was accompanied by a paradoxical worsening of clinical signs. Notably, vagal sensory ganglia neuroinflammation was induced by IAV infection and this was significantly potentiated by QX-314 administration. This vagal ganglia hyperinflammation was characterized by alterations in IAV-induced host defense gene expression, increased neuropeptide gene and protein expression, and an increase in the number of inflammatory cells present within the ganglia. These data suggest that pulmonary vagal sensory neurons play a role in the regulation of the inflammatory process during IAV infection and suggest that vagal neuroinflammation may be an important contributor to IAV pathogenesis and clinical presentation. Targeting these pathways could offer therapeutic opportunities to treat IAV-induced morbidity and mortality.

Linoleic acid blunts early osteoblast differentiation and impairs oxidative phosphorylation in vitro

BACKGROUND

Linoleic acid (LNA), an essential polyunsaturated fatty acid (PUFA), plays a crucial role in cellular functions. However, excessive intake of LNA, characteristic of Western diets, can have detrimental effects on cells and organs. Human observational studies have shown an inverse relationship between plasma LNA concentrations and bone mineral density. The mechanism by which LNA impairs the skeleton is unclear, and there is a paucity of research on the effects of LNA on bone-forming osteoblasts.

METHODS

The effect of LNA on osteoblast differentiation, cellular bioenergetics, and production of oxidized PUFA metabolites in vitro, was studied using primary mouse bone marrow stromal cells (BMSC) and MC3T3-E1 osteoblast precursors.

RESULTS

LNA treatment decreased alkaline phosphatase activity, an early marker of osteoblast differentiation, but had no effect on committed osteoblasts or on mineralization by differentiated osteoblasts. LNA suppressed osteoblast commitment by blunting the expression of Runx2 and Osterix, key transcription factors involved in osteoblast differentiation, and other key osteoblast-related factors involved in bone formation. LNA treatment was associated with increased production of oxidized LNA- and arachidonic acid-derived metabolites and blunted oxidative phosphorylation, resulting in decreased ATP production.

CONCLUSION

Our results show that LNA inhibited early differentiation of osteoblasts and this inhibitory effect was associated with increased production of oxidized PUFA metabolites that likely impaired energy production via oxidative phosphorylation.

The re-emerging role of linoleic acid in paediatric asthma

Asthma is the most common chronic disease within the paediatric population. Although it is multifactorial, its onset may be linked to early-life exposures with subsequent impact on immune system development. Microbial and dietary metabolic products have been implicated in the development and exacerbation of paediatric asthma. Linoleic acid is the most common omega-6 polyunsaturated fatty acid in the Western diet. In this review, we summarise the literature regarding the involvement of linoleic acid in the development of and its impact on existing paediatric asthma. First, we summarise the existing knowledge surrounding the relationship between human microbial metabolism and allergic diseases in children. Next, we examine cellular or animal model-based mechanistic studies that investigated the impact of dietary- and microbial-derived linoleic acid metabolites on asthma. Finally, we review the literature investigating the impact of linoleic acid metabolites on the development and exacerbation of childhood asthma. While there is conflicting evidence, there is growing support for a role of linoleic acid in the onset and pathophysiology of asthma. We recommend that additional cellular, animal, and longitudinal studies are performed that target linoleic acid and its metabolites.

Neural Mechanisms Underlying the Coughing Reflex

Breathing is an intrinsic natural behavior and physiological process that maintains life. The rhythmic exchange of gases regulates the delicate balance of chemical constituents within an organism throughout its lifespan. However, chronic airway diseases, including asthma and chronic obstructive pulmonary disease, affect millions of people worldwide. Pathological airway conditions can disrupt respiration, causing asphyxia, cardiac arrest, and potential death. The innervation of the respiratory tract and the action of the immune system confer robust airway surveillance and protection against environmental irritants and pathogens. However, aberrant activation of the immune system or sensitization of the nervous system can contribute to the development of autoimmune airway disorders. Transient receptor potential ion channels and voltage-gated Na+ channels play critical roles in sensing noxious stimuli within the respiratory tract and interacting with the immune system to generate neurogenic inflammation and airway hypersensitivity. Although recent studies have revealed the involvement of nociceptor neurons in airway diseases, the further neural circuitry underlying airway protection remains elusive. Unraveling the mechanism underpinning neural circuit regulation in the airway may provide precise therapeutic strategies and valuable insights into the management of airway diseases.

Production profile of lipid mediators in conjunctival lavage fluid in allergic and infectious conjunctivitis in guinea pigs

Introduction

Conjunctivitis is a major ocular disease classified into allergic or infectious. The pathological features of conjunctivitis are not fully understood despite its high morbidity rate; thus, its differentiation can be difficult.

Materials and methods

We used ovalbumin-induced allergic conjunctivitis and lipopolysaccharide-induced infectious conjunctivitis models of guinea pigs. Both models showed conjunctival swelling. Histological studies revealed that numerous eosinophils infiltrated the conjunctiva in the allergic model, whereas neutrophils infiltrated the conjunctiva in the infectious model. We collected conjunctival lavage fluid (COLF) and comprehensively analyzed lipid production using liquid chromatography-tandem mass spectrometry.

Results

COLF showed increase of 20 and 12 lipid species levels in the allergic and infectious models, respectively. Specifically, the levels of a major allergic mediator, prostaglandin D₂ and its three metabolites and several cytochrome P450-catalyzed lipids increased in the allergic model. In the infectious model, the levels of prostaglandin E₂ and 8-iso-prostaglandin E₂ increased, indicating tissue inflammation. Moreover, the level of 12-oxo-eicosatetraenoic acid, a lipoxygenase metabolite, increased in the infectious model.

Conclusion

These differences in lipid production in the COLF reflected the pathological features of allergic and infectious conjunctivitis.

The activities and mechanisms of intestinal microbiota metabolites of TCM herbal ingredients could be illustrated by a strategy integrating spectrum-effects, network pharmacology, metabolomics and molecular docking analysis: Platycodin D as an example

BACKGROUND

The intestinal microbiota plays a key role in understanding the mechanism of traditional Chinese medicine (TCM), as it could transform the herbal ingredients to metabolites with higher bioavailability and activity comparing to their prototypes. Nevertheless, the study of the activity and mechanism of microbiota metabolites reported by the published literature still lacks viable ways. Hence a new strategy is proposed to solve this issue.

PURPOSE

A new strategy to study the activity and mechanism of intestinal microbiota metabolites of TCM herbal ingredients by integrating spectrum-effect relationship, network pharmacology, metabolomics analysis and molecular docking together was developed and proposed.

METHOD

Platycodin D (PD) and its microbiota metabolites with antitussive and expectorant effect were selected as an example for demonstration. First, the PD and its microbiota metabolites with important contribution to antitussive and/or expectorant effects were screened through spectrum-effect relationship analysis. Second, network pharmacology and metabolomics analysis were integrated to identify the upstream key targets of PD and its microbiota metabolites as well as the downstream endogenous metabolites. Finally, the active forms of PD were further confirmed by molecular docking.

RESULTS

Results showed that PD was an active ingredient with antitussive and/or expectorant effects, and the active forms of PD were its microbiota metabolites: 3-O-β-d-glucopyranosyl platycodigenin, 3-O-β-d-glucopyranosyl isoplatycodigenin, 7‑hydroxyl-3-O-β-d-glucopyranosyl platycodigenin, platycodigenin and isoplatycodigenin. In addition, those microbiota metabolites could bind the key targets of PAH, PLA2G2A, ALOX5, CYP2C9 and CYP2D6 to exert antitussive effects by regulating four metabolic pathways of phenylalanine, tyrosine and tryptophan biosynthesis, phenylalanine metabolism, glycerophospholipid metabolism and linoleic acid metabolism. Similarly, they could also bind the key targets of PLA2G1B, ALOX5, CYP2C9 and CYP2D6 to exert expectorant effect by regulating two pathways of glycerophospholipid metabolism and linoleic acid metabolism.

CONCLUSION

The proposed strategy paves a new way for the illustration of the activities and mechanisms of TCM herbal ingredients, which is very important to reconcile the conundrums of TCM herbal ingredients with low oral bioavailability but high activity.

Cellular Distribution of Secreted Phospholipase A2 in Lungs of IPF Patients and Its Inhibition in Bleomycin-Induced Pulmonary Fibrosis in Mice

Idiopathic pulmonary fibrosis (IPF) is a chronic lung disease with a very poor prognosis as it has a 2.5 to 5 years mean survival after proper diagnosis. Even nintedanib and pirfenidone cannot halt the progression, though they slow the progression of IPF. Hence, there is a need to understand the novel pathophysiology. Phospholipase A2 (PLA2) could be the ideal candidate to study in IPF, as they have a role in both inflammation and fibrosis. In the present study, we have shown the expression profile of various secretory Phospholipase A2 (PLA2) isoforms by analyzing publicly available transcriptome data of single cells from the lungs of healthy individuals and IPF patients. Among 11 members of sPLA2, PLA2G2A is found to be increased in the fibroblasts and mesothelial cells while PLA2G5 is found to be increased in the fibroblasts of IPF patients. We identified a subset of fibroblasts expressing high PLA2G2A with moderate expression of PLA2G5 and which are specific to IPF only; we named it as PLA2G2A+ IPF fibroblast. Pathway analysis revealed that these PLA2G2A+ IPF fibroblast have upregulation of both inflammatory and fibrosis-related pathways like the TGF-β signaling pathway, IL-17 signaling, the arachidonic acid metabolism pathway and ECM-receptor interaction. In addition to this, we found elevated levels of sPLA2-IIA in plasma samples of IPF patients in our cohort. PLA2G3, PLA2G10 and PLA2G12B are found in to be increased in certain epithelial cells of IPF patients. Thus, these findings indicate that these five isoforms have a disease-dominant role along with innate immune roles as these isoforms are found predominantly in structural cells of IPF patients. Further, we have targeted sPLA2 in mice model of bleomycin-induced lung fibrosis by pBPB, a known sPLA2 inhibitor. pBPB treatment attenuated lung fibrosis induced by bleomycin along with a reduction in TGF-β and deposition of extracellular matrix in lung. Thus, these findings indicate that these sPLA2 isoforms especially PLA2G2A may serve as a therapeutic target in lung fibrosis.

Multi-Omics Analysis of Lung Tissue Demonstrates Changes to Lipid Metabolism during Allergic Sensitization in Mice

Allergy and asthma pathogenesis are associated with the dysregulation of metabolic pathways. To understand the effects of allergen sensitization on metabolic pathways, we conducted a multi-omics study using BALB/cJ mice sensitized to house dust mite (HDM) extract or saline. Lung tissue was used to perform untargeted metabolomics and transcriptomics while both lung tissue and plasma were used for targeted lipidomics. Following statistical comparisons, an integrated pathway analysis was conducted. Histopathological changes demonstrated an allergic response in HDM-sensitized mice. Untargeted metabolomics showed 391 lung tissue compounds were significantly different between HDM and control mice (adjusted p < 0.05); with most compounds mapping to glycerophospholipid and sphingolipid pathways. Several lung oxylipins, including 14-HDHA, 8-HETE, 15-HETE, 6-keto-PGF1α, and PGE2 were significantly elevated in HDM-sensitized mice (p < 0.05). Global gene expression analysis showed upregulated calcium channel, G protein–signaling, and mTORC1 signaling pathways. Genes related to oxylipin metabolism such as Cox, Cyp450s, and cPla2 trended upwards. Joint analysis of metabolomics and transcriptomics supported a role for glycerophospholipid and sphingolipid metabolism following HDM sensitization. Collectively, our multi-omics results linked decreased glycerophospholipid and sphingolipid compounds and increased oxylipins with allergic sensitization; concurrent upregulation of associated gene pathways supports a role for bioactive lipids in the pathogenesis of allergy and asthma.

Apigenin ameliorates non-eosinophilic inflammation, dysregulated immune homeostasis and mitochondria-mediated airway epithelial cell apoptosis in chronic obese asthma via the ROS-ASK1-MAPK pathway

BACKGROUND

Obese asthma is one of the important asthma phenotypes that have received wide attention in recent years. Excessive oxidative stress and different inflammatory endotypes may be important reasons for the complex symptoms, frequent aggravation, and resistance to traditional treatments of obese asthma. Apigenin (API), is a flavonoid natural small molecule compound with good anti-inflammatory and antioxidant activity in various diseases and proved to have the potential efficacy to combat obese asthma.

METHODS

In vivo, this study fed C57BL/6 J mice with high-fat diets(HFD)for 12 weeks and then stimulated them with OVA for 6 weeks to establish a model of chronic obese asthma, while different doses of oral API or dexamethasone were used for therapeutic interventions. In vitro, this study used HDM to stimulate human bronchial cells (HBEs) to establish the model and intervened with API or Selonsertib (SEL).

RESULTS

This study clarified that OVAinduced a type of mixed granulocytic asthma with elevated neutrophils and eosinophils in obese male mice fed with long-term HFD, which also exhibited mixed TH17/TH1/TH2 inflammation. Apigenin effectively suppressed this complex inflammation and acted as a regulator of immune homeostasis. Meanwhile, apigenin reduced AHR, inflammatory cell infiltration, airway epithelial cell apoptosis, airway collagen deposition, and lung oxidative stress via the ROS-ASK1-MAPK pathway in an obese asthma mouse model. In vitro, this study found that apigenin altered the binding status of TRAF6 to ASK1, inhibited ASK1 phosphorylation, and protected against ubiquitin-dependent degradation of ASK1, suggesting that ROS-activated ASK1 may be an important target for apigenin to exert anti-inflammatory and anti-apoptotic effects. To further verify the intervention mechanism, this study clarified that apigenin improved cell viability and mitochondrial function and inhibited apoptosis by interfering with the ROS-ASK1-MAPK pathway.

CONCLUSIONS

This study demonstrates for the first time the therapeutic effect of apigenin in chronic obese asthma and further clarifies its potential therapeutic targets. In addition, this study clarifies the specificity of chronic obese asthma and provides new options for its treatment.

Airway Epithelium: A Neglected but Crucial Cell Type in Asthma Pathobiology

The features of allergic asthma are believed to be mediated mostly through the Th2 immune response. In this Th2-dominant concept, the airway epithelium is presented as the helpless victim of Th2 cytokines. However, this Th2-dominant concept is inadequate to fill some of the vital knowledge gaps in asthma pathogenesis, like the poor correlation between airway inflammation and airway remodeling and severe asthma endotypes, including Th2-low asthma, therapy resistance, etc. Since the discovery of type 2 innate lymphoid cells in 2010, asthma researchers started believing in that the airway epithelium played a crucial role, as alarmins, which are the inducers of ILC2, are almost exclusively secreted by the airway epithelium. This underscores the eminence of airway epithelium in asthma pathogenesis. However, the airway epithelium has a bipartite functionality in sustaining healthy lung homeostasis and asthmatic lungs. On the one hand, the airway epithelium maintains lung homeostasis against environmental irritants/pollutants with the aid of its various armamentaria, including its chemosensory apparatus and detoxification system. Alternatively, it induces an ILC2-mediated type 2 immune response through alarmins to amplify the inflammatory response. However, the available evidence indicates that restoring epithelial health may attenuate asthmatic features. Thus, we conjecture that an epithelium-driven concept in asthma pathogenesis could fill most of the gaps in current asthma knowledge, and the incorporation of epithelial-protective agents to enhance the robustness of the epithelial barrier and the combative capacity of the airway epithelium against exogenous irritants/allergens may mitigate asthma incidence and severity, resulting in better asthma control.

Arachidonate 15-lipoxygenase type B: Regulation, function, and its role in pathophysiology

As a lipoxygenase (LOX), arachidonate 15-lipoxygenase type B (ALOX15B) peroxidizes polyenoic fatty acids (PUFAs) including arachidonic acid (AA), eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), and linoleic acid (LA) to their corresponding fatty acid hydroperoxides. Distinctive to ALOX15B, fatty acid oxygenation occurs with positional specificity, catalyzed by the non-heme iron containing active site, and in addition to free PUFAs, membrane-esterified fatty acids serve as substrates for ALOX15B. Like other LOX enzymes, ALOX15B is linked to the formation of specialized pro-resolving lipid mediators (SPMs), and altered expression is apparent in various inflammatory diseases such as asthma, psoriasis, and atherosclerosis. In primary human macrophages, ALOX15B expression is associated with cellular cholesterol homeostasis and is induced by hypoxia. Like in inflammation, the role of ALOX15B in cancer is inconclusive. In prostate and breast carcinomas, ALOX15B is attributed a tumor-suppressive role, whereas in colorectal cancer, ALOX15B expression is associated with a poorer prognosis. As the biological function of ALOX15B remains an open question, this review aims to provide a comprehensive overview of the current state of research related to ALOX15B.

A Comprehensive Analysis of Microflora and Metabolites in the Development of Ulcerative Colitis into Colorectal Cancer Based on the Lung–Gut Correlation Theory

The lungs and large intestine can co-regulate inflammation and immunity through the lung–gut axis, in which the transportation of the gut microbiota and metabolites is the most important communication channel. In our previous study, not only did the composition of the gut microbiota and metabolites related to inflammation change significantly during the transition from ulcerative colitis (UC) to colorectal cancer (CRC), but the lung tissues also showed corresponding inflammatory changes, which indicated that gastrointestinal diseases can lead to pulmonary diseases. In order to elucidate the mechanisms of this lung–gut axis, metabolites in bronchoalveolar lavage fluid (BALF) and lung tissues were detected using UHPLC–Q-TOF-MS/MS technology, while microbiome characterization was performed in BALF using 16S rDNA sequencing. The levels of pulmonary metabolites changed greatly during the development of UC to CRC. Among these changes, the concentrations of linoleic acid and 7-hydroxy-3-oxocholic acid gradually increased during the development of UC to CRC. In addition, the composition of the pulmonary microbiota also changed significantly, with an increase in the Proteobacteria and an obvious decrease in the Firmicutes. These changes were consistent with our previous studies of the gut. Collectively, the microbiota and metabolites identified above might be the key markers related to lung and gut diseases, which can be used as an indication of the transition of diseases from the gut to the lung and provide a scientific basis for clinical treatment.

Clinical Characteristics and Management Strategies for Adult Obese Asthma Patients

The rates of asthma and obesity are increasing concurrently in the United States. Epidemiologic studies demonstrate that the incidence of asthma increases with obesity. Furthermore, obese individuals have asthma that is more severe, harder to control, and resistant to standard medications. In fact, specific asthma-obesity phenotypes have been identified. Various pathophysiologic mechanisms, including mechanical, inflammatory, metabolic and microbiome-associated, are at play in promulgating the obese-asthma phenotypes. While standard asthma medications, such as inhaled corticosteroids and biologics, are currently used to treat obese asthmatics, they may have limited effectiveness. Targeting the underlying aberrant processes, such as addressing steroid resistance, microbiome, metabolic and weight loss approaches, may be helpful.

PlexinD1 Deficiency in Lung Interstitial Macrophages Exacerbates House Dust Mite-Induced Allergic Asthma

Interstitial macrophages (IMs) are key regulators of allergic inflammation. We previously showed that the absence of semaphorin 3E (Sema3E) exacerbates asthma features in both acute and chronic asthma models. However, it has not been studied whether Sema3E, via its receptor plexinD1, regulates IM function in allergic asthma. Therefore, we investigated the role of plexinD1 deficiency on IMs in allergic asthma. We found that the absence of plexinD1 in IMs increased airway hyperresponsiveness, airway leukocyte numbers, allergen-specific IgE, goblet cell hyperplasia, and Th2/Th17 cytokine response in the house dust mite (HDM)-induced allergic asthma model. Muc5ac, Muc5b, and α-SMA genes were increased in mice with Plxnd1-deficient IMs compared with wild-type mice. Furthermore, plexinD1-deficient bone marrow-derived macrophages displayed reduced IL-10 mRNA expression, at both the baseline and following HDM challenge, compared with their wild-type counterpart mice. Our data suggest that Sema3E/plexinD1 signaling in IMs is a critical pathway that modulates airway inflammation, airway resistance, and tissue remodeling in the HDM murine model of allergic asthma. Reduced IL-10 expression by plexinD1-deficient macrophages may account for these enhanced allergic asthma features.

Mitochondrial dynamics and mitophagy in lung disorders

Mitochondria are biosynthetic, bioenergetic, and signaling organelles which are critical for physiological adaptations and cellular stress responses to the environment. Various endogenous and environmental stress affects critical processes in mitochondrial homeostasis such as oxidative phosphorylation, biogenesis, mitochondrial redox system which leads to the formation of reactive oxygen species (ROS) and free radicals. The state of function of the mitochondrion is particularly dependent on the dynamic balance between mitochondrial biogenesis, fusion and fission, and degradation of damaged mitochondria by mitophagy. Increasing evidence has suggested a prominent role of mitochondrial dysfunction in the onset and progression of various lung pathologies, ranging from acute to chronic disorders. In this comprehensive review, we discuss the emerging findings of multifaceted regulations of mitochondrial dynamics and mitophagy in normal lung homeostasis as well as the prominence of mitochondrial dysfunction as a determining factor in different lung disorders such as lung cancer, COPD, IPF, ALI/ARDS, BPD, and asthma. The review will contribute to the existing understanding of critical molecular machinery regulating mitochondrial dynamic state during these pathological states. Furthermore, we have also highlighted various molecular checkpoints involved in mitochondrial dynamics, which may serve as hopeful therapeutic targets for the development of potential therapies for these lung disorders.

Long Chain Fatty Acids as Modulators of Immune Cells Function: Contribution of FFA1 and FFA4 Receptors

Long-chain fatty acids are molecules that act as metabolic intermediates and constituents of membranes; however, their novel role as signaling molecules in immune function has also been demonstrated. The presence of free fatty acid (FFA) receptors on immune cells has contributed to the understanding of this new role of long-chain fatty acids (LCFAs) in immune function, showing their role as anti-inflammatory or pro-inflammatory molecules and elucidating their intracellular mechanisms. The FFA1 and FFA4 receptors, also known as GPR40 and GPR120, respectively, have been described in macrophages and neutrophils, two key cells mediating innate immune response. Ligands of the FFA1 and FFA4 receptors induce the release of a myriad of cytokines through well-defined intracellular signaling pathways. In this review, we discuss the cellular responses and intracellular mechanisms activated by LCFAs, such as oleic acid, linoleic acid, palmitic acid, docosahexaenoic acid (DHA), and eicosapentaenoic acid (EPA), in T-cells, macrophages, and neutrophils, as well as the role of the FFA1 and FFA4 receptors in immune cells.

Potential Metabolic Biomarkers in Adult Asthmatics

Asthma is the most common chronic airway inflammation, with multiple phenotypes caused by complicated interactions of genetic, epigenetic, and environmental factors. To date, various determinants have been suggested for asthma pathogenesis by a new technology termed omics, including genomics, transcriptomics, proteomics, and metabolomics. In particular, the systematic analysis of all metabolites in a biological system, such as carbohydrates, amino acids, and lipids, has helped identify a novel pathway related to complex diseases. These metabolites are involved in the regulation of hypermethylation, response to hypoxia, and immune reactions in the pathogenesis of asthma. Among them, lipid metabolism has been suggested to be related to lung dysfunction in mild-to-moderate asthma. Sphingolipid metabolites are an important mediator contributing to airway inflammation in obese asthma and aspirin-exacerbated respiratory disease. Although how these molecular variants impact the disease has not been completely determined, identification of new causative factors may possibly lead to more-personalized and precise pathway-specific approaches for better diagnosis and treatment of asthma. In this review, perspectives of metabolites related to asthma and clinical implications have been highlighted according to various phenotypes.

Plasma lipid biomarkers in relation to BMI, lung function, and airway inflammation in pediatric asthma

INTRODUCTION

There is limited understanding of how plasma fatty acid levels affect pulmonary function in pediatric years. It has been speculated that polyunsaturated fatty acids influence asthma via anti or pro-inflammatory mechanisms. Metabolomics presents a new and promising resource for identifying molecular processes involved in asthma pathology.

OBJECTIVES

We investigated the relationship of plasma fatty acid metabolites as biomarkers of the 'mild-asthma' phenotype and lung function including airway inflammation in children.

METHODS

This cross-sectional study involved 64 children (5-12 years, 33 male) with mild-asthma phenotype attending an outpatient pediatric clinic in Athens, Greece. Clinical examination included spirometry (FVC, FEV₁, FEV₁/FVC, PEF, FEF_25-75%) and Fractional exhaled Nitric Oxide (FeNO). Targeted metabolomic profiling was used to quantify plasma fatty acid composition. Associations between lipids and pulmonary function indices were investigated applying linear regression.

RESULTS

Targeted GC-MS identified 25 unique plasma fatty acids in mild-asthmatic children. Linear regression revealed significant associations between linoleic, oleic, erucic, cis-11-eicosenoic, arachidic acids and FEV₁, FVC, FEV₁/FVC, PEF, FEF_25-75% and FeNO in the overweight/obese group, adjusting for age and sex; and in the normo-weight between stearic and arachidic acids versus FEV₁ and FEV₁/FVC respectively. No associations were observed for arachidonic, α-linolenic, EPA and DHA.

CONCLUSION

Metabolomics is a novel science that is useful to discover metabolic signatures specific to disease. Evaluation of fatty acid status could assist clinicians in decision-making about a dietary modification that can be used for personalized nutrition therapies to achieve better asthma control, optimum lung function, and therapeutic response in children.

Gu-Ben-Fang-Xiao decoction modulates lipid metabolism by activating the AMPK pathway in asthma remission

Gu-Ben-Fang-Xiao decoction (GBFXD), derived from the traditional Chinese medicine Yu-Ping-Feng-San, is widely used in clinical settings and has obvious curative effects in respiratory diseases. GBFXD regulates cholesterol transport and lipid metabolism in chronic persistent asthma. There is evidence for its beneficial effects in the remission stage of asthma; however, its metabolic regulatory effects and underlying mechanisms during asthma remission are unclear. In the present study, we used liquid chromatography-mass spectrometry (LC-MS) to analyse the metabolic profile of mouse serum during asthma remission. The acquired LC-MS data were subjected to a multivariate analysis for identification of significantly altered metabolites. In total, 42 metabolites were significantly differentially expressed among the control, model, and GBFXD groups. In particular, levels of fatty acids, acylcarnitines, phosphatidylcholines, phosphatidylethanolamines, phosphatidylinositols, triglycerides, and diacylglycerols were altered during asthma remission. GBFXD may maintain lipid homeostasis on the lung surface by modulating lipid metabolism and may thereby alleviate asthma. We further quantified hypogeic acid (FA 16:1) based on targeted metabolomics and found that GBFXD may regulate fatty acid metabolism by activating the AMP-activated protein kinase (AMPK) pathway. These results support the use of GBFXD in patients with asthma remission.

Oxidative stress and obesity-related asthma

Obesity is an asthma comorbidity associated with poor control, increased exacerbation risk and reduced response to inhaled and systemic corticosteroids. It affects children and adults differentially. In those with early onset asthma, it associated with increased eosinophilic inflammation, whereas in late onset, it correlates with lower nitric oxide (NO) and predominantly non-T2 inflammation. There are probably multiple pathways by which obesity impacts asthma; airway and systemic oxidative stress has been proposed as a mechanism that could potentially explain the obesity mediated increased comorbidity and poor response to treatment. More likely than not, oxidative stress is an epiphenomenon of a very diverse set of processes driven by complex changes in airway and systemic metabolism. This article provides a comprehensive overview of the clinical, metabolic, pathophysiological and therapeutic aspects of oxidative stress in patients with obesity and asthma.

β-Glucosylceramide From Allergic Mothers Enhances Offspring Responsiveness to Allergen

In animals and humans, offspring of allergic mothers have increased responsiveness to allergen and the allergen-specificity of the offspring can be different than that of the mother. In our preclinical models, the mother's allergic responses influence development of the fetus and offspring by elevating numbers of cells in dendritic cell subsets. A major question is the identity of maternal factors of allergic mothers that alter offspring development of responsiveness to allergen. Lipids are altered during allergic responses and lipids are transported to the fetus for growth and formation of fetal membranes. We hypothesized that pro-inflammatory lipids, that are elevated in allergic mothers, are transported to the fetus and regulate fetal immune development. We demonstrate in this report that there was a significant 2-fold increase in β-glucosylceramides (βGlcCer) in allergic mothers, the fetal liver and her offspring. The βGlcCer were transported from mother's plasma, across the placenta, to the fetus and in breastmilk to the offspring. Administration of βGlcCer to non-allergic mothers was sufficient for offspring responses to allergen. Importantly, maternal administration of a clinically relevant pharmacological inhibitor of βGlcCer synthase returned βGlcCer to normal levels in the allergic mothers and her offspring and blocked the offspring increase in dendritic cell subsets and offspring allergen responsiveness. In summary, allergic mothers had increased βGlcCer that was transported to offspring and mediated increases in offspring DCs and responsiveness to allergen. These data have a significant impact on our understanding of mechanisms for development of allergies in offspring of allergic mothers and have the potential to lead to novel interventions that significantly impact risk for allergic disease early in life.

Ku70 modulation alleviates murine allergic asthma features and restores mitochondrial function in lungs

The airway epithelium is continuously exposed to a variety of pollutants and allergens, thanks to both natural and manmade environmental pollution. With numerous protective mechanisms, the airway epithelium protects the lungs. DNA repair mechanism is one such protective response and its failure could lead to the accumulation of DNA mutations. Our lab had earlier demonstrated the dysfunctional mitochondria in airway epithelium of the asthmatic mice lungs. Here, we show that Ku70 modulation by the administration of Ku70 plasmid attenuates asthma features and reduces mitochondrial dysfunction in the lungs of allergen exposed mice. Ku70 is a key DNA repair protein with diverse roles including VDJ recombination, telomere maintenance, and maintenance of cell homeostasis. Recently, we found a reduction in Ku70 expression in asthmatic airway epithelium, and this was associated with mitochondrial dysfunction in asthmatic condition. In this study, we have shown that Ku70 over-expression in asthmatic mice attenuated airway hyperresponsiveness, airway inflammation, sub-epithelial fibrosis along with reduction in TGF-β with no effect in IL-13 levels and goblet cell metaplasia. Ku70 over-expression in asthmatic mice reduced 8-isoprostane, a marker of oxidative stress, and restored the mitochondrial function in asthmatic mice. We further found these roles of Ku70 to be independent of DNA damage as Ku70 overexpressed mice did not show any reduction in DNA tail, an index of DNA damage. Thus, our findings indicate that Ku70 can attenuate crucial features of asthma along with the restoration of mitochondrial function. This implies that Ku70 could be a therapeutic target for asthma without affecting DNA repair function.

TRPV1 Channel: A Noxious Signal Transducer That Affects Mitochondrial Function

The Transient Receptor Vanilloid 1 (TRPV1) or capsaicin receptor is a nonselective cation channel, which is abundantly expressed in nociceptors. This channel is an important transducer of several noxious stimuli, having a pivotal role in pain development. Several TRPV1 studies have focused on understanding its structure and function, as well as on the identification of compounds that regulate its activity. The intracellular roles of these channels have also been explored, highlighting TRPV1′s actions in the homeostasis of Ca²⁺ in organelles such as the mitochondria. These studies have evidenced how the activation of TRPV1 affects mitochondrial functions and how this organelle can regulate TRPV1-mediated nociception. The close relationship between this channel and mitochondria has been determined in neuronal and non-neuronal cells, demonstrating that TRPV1 activation strongly impacts on cell physiology. This review focuses on describing experimental evidence showing that TRPV1 influences mitochondrial function.

A looming role of mitochondrial calcium in dictating the lung epithelial integrity and pathophysiology of lung diseases

With the increasing appreciation of mitochondria in modulating cellular homeostasis, various disease biology researchers have started exploring the detailed role of mitochondria in multiple diseases beyond neuronal and muscular diseases. In this context, emerging shreds of evidence in lung biology indicated the meticulous role of lung epithelia in provoking a plethora of lung diseases in contrast to earlier beliefs. As lung epithelia are ceaselessly exposed to the environment, they need to have multiple protective mechanisms to maintain the integrity of lung structure and function. As ciliated airway epithelium and type 2 alveolar epithelia require intense energy for executing their key functions like ciliary beating and surfactant production, it is no surprise that defects in mitochondrial function in these cells could perturb lung homeostasis and engage in the pathophysiology of lung diseases. On one hand, intracellular calcium plays the central role in executing key functions of lung epithelia, and on the other hand maintenance of intracellular calcium needs the buffering role of mitochondria. Thus, the regulation of mitochondrial calcium in lung epithelia seems to be critical in lung homeostasis and could be decisive in the pathogenesis of various lung diseases.

Noncanonical role for Ku70/80 in the prevention of allergic airway inflammation via maintenance of airway epithelial cell organelle homeostasis

Airway epithelial homeostasis is under constant threat due to continuous exposure to the external environment, and abnormally robust sensitivity to external stimuli is critical to the development of airway diseases, including asthma. Ku is a key nonhomologous end-joining DNA repair protein with diverse cellular functions such as VDJ recombination and telomere length maintenance. Here, we show a novel function of Ku in alleviating features of allergic airway inflammation via the regulation of mitochondrial and endoplasmic reticulum (ER) stress. We first determined that airway epithelial cells derived from both asthmatic lungs and murine asthma models demonstrate increased expression of 8-hydroxy-deoxyguanosine (8-OHdG), a marker of oxidative DNA damage. Ku protein expression was dramatically reduced in the bronchial epithelium of patients with asthma as well as in human bronchial epithelial cells exposed to oxidative stress. Knockdown of Ku70 or Ku80 in naïve mice elicited mitochondrial collapse or ER stress, leading to bronchial epithelial cell apoptosis and spontaneous development of asthma-like features, including airway hyperresponsiveness, airway inflammation, and subepithelial fibrosis. These findings demonstrate an essential noncanonical role for Ku proteins in asthma pathogenesis, likely via maintenance of organelle homeostasis. This novel function of Ku proteins may also be important in other disease processes associated with organelle stress.

Co-opting oxylipin signals in microbial disease

Oxylipins, or oxygenated lipids, are universal signalling molecules across all kingdoms of life. These molecules, either produced by microbial pathogens or their mammalian host, regulate inflammation during microbial infection. In this review, we summarise current literature on the biosynthesis pathways of microbial oxylipins and their biological activity towards mammalian cells. Collectively, these studies have illustrated how microbial pathogens can modulate immune rsponse and disease outcome via oxylipin-mediated mechanisms.

Oxidized Phospholipids in Healthy and Diseased Lung Endothelium

Circulating and cell membrane phospholipids undergo oxidation caused by enzymatic and non-enzymatic mechanisms. As a result, a diverse group of bioactive oxidized phospholipids generated in these conditions have both beneficial and harmful effects on the human body. Increased production of oxidized phospholipid products with deleterious effects is linked to the pathogenesis of various cardiopulmonary disorders such as atherosclerosis, thrombosis, acute lung injury (ALI), and inflammation. It has been determined that the contrasting biological effects of lipid oxidation products are governed by their structural variations. For example, full-length products of 1-palmitoyl-2-arachidonoyl-sn-glycero-3-phosphorylcholine oxidation (OxPAPC) have prominent endothelial barrier protective and anti-inflammatory activities while most of the truncated oxidized phospholipids induce vascular leak and exacerbate inflammation. The extensive studies from our group and other groups have demonstrated a strong potential of OxPAPC in mitigating a wide range of agonist-induced lung injuries and inflammation in pulmonary endothelial cell culture and rodent models of ALI. Concurrently, elevated levels of truncated oxidized phospholipids are present in aged mice lungs that potentiate the inflammatory agents-induced lung injury. On the other hand, increased levels of full length OxPAPC products accelerate ALI recovery by facilitating production of anti-inflammatory lipid mediator, lipoxin A4, and other molecules with anti-inflammatory properties. These findings suggest that OxPAPC-assisted lipid program switch may be a promising therapeutic strategy for treatment of acute inflammatory syndromes. In this review, we will summarize the vascular-protective and deleterious aspects of oxidized phospholipids and discuss their therapeutic potential including engineering of stable analogs of oxidized phospholipids with improved anti-inflammatory and barrier-protective properties.

Perturbed mitochondrial dynamics, an emerging aspect of epithelial-microbe interactions

Mitochondria exist in a complex network that is constantly remodeling via the processes of fission and fusion in response to intracellular conditions and extracellular stimuli. Excessive fragmentation of the mitochondrial network because of an imbalance between fission and fusion reduces the cells' capacity to generate ATP and can be a forerunner to cell death. Given the critical roles mitochondria play in cellular homeostasis and innate immunity, it is not surprising that many microbial pathogens can disrupt mitochondrial activity. Here we note the putative contribution of mitochondrial dysfunction to gut disease and review data showing that infection with microbial pathogens can alter the balance between mitochondrial fragmentation and fusion, preventing normal remodeling (i.e., dynamics) and can lead to cell death. Current data indicate that infection of epithelia or macrophages with microbial pathogens will ultimately result in excessive fragmentation of the mitochondrial network. Concerted research efforts are required to elucidate fully the processes that regulate mitochondrial dynamics, the mechanisms by which microbes affect epithelial mitochondrial fission and/or fusion, and the implications of this for susceptibility to infectious disease. We speculate that the commensal microbiome of the gut may be important for normal epithelial mitochondrial form and function. Drugs designed to counteract the effect of microbial pathogen interference with mitochondrial dynamics may be a new approach to infectious disease at mucosal surfaces.

Dysfunction of transient receptor potential ion channels as an important pathophysiological mechanism in asthma

Asthma is a chronic heterogeneous disease characterized by chronic inflammation and bronchial hyperreactivity. Neurogenic inflammation is one of the important causes of hyperreactivity. Dysfunction of transient receptor potential (TRP) ion channels underlies the development of neurogenic inflammation, bronchial hyperreactivity and respiratory symptoms of asthma such as bronchospasm and cough. TRP channels are expressed in the respiratory tract. Their activation is mediated by endogenous and exogenous factors involved in the pathogenesis of asthma. The study of functioning and regulation of TRP channels is relevant, as they could be important therapeutic targets for asthma. The aim of the review is to summarize modern ideas about the mechanisms of functioning and regulation of members of the TRP channel superfamily, the role of which in lung pathology and physiology are the best studied.

Oxidised metabolites of the omega-6 fatty acid linoleic acid activate dFOXO

Obesity-induced inflammation, or meta-inflammation, plays key roles in metabolic syndrome and is a significant risk factor in diabetes and cardiovascular disease. To investigate causal links between obesity, meta-inflammation, and insulin signaling we established a Drosophila model to determine how elevated dietary fat and changes in the levels and balance of saturated fatty acids (SFAs) and polyunsaturated fatty acids (PUFAs) influence inflammation. We observe negligible effect of saturated fatty acid on inflammation but marked enhancement or suppression by omega-6 and omega-3 PUFAs, respectively. Using combined lipidomic and genetic analysis, we show omega-6 PUFA enhances meta-inflammation by producing linoleic acid-derived lipid mediator 9-hydroxy-octadecadienoic acid (9-HODE). Transcriptome analysis reveals 9-HODE functions by regulating FOXO family transcription factors. We show 9-HODE activates JNK, triggering FOXO nuclear localisation and chromatin binding. FOXO TFs are important transducers of the insulin signaling pathway that are normally down-regulated by insulin. By activating FOXO, 9-HODE could antagonise insulin signaling providing a molecular conduit linking changes in dietary fatty acid balance, meta-inflammation, and insulin resistance.

Integration of epidemiologic, pharmacologic, genetic and gut microbiome data in a drug-metabolite atlas

Progress in high-throughput metabolic profiling provides unprecedented opportunities to obtain insights into the effects of drugs on human metabolism. The Biobanking BioMolecular Research Infrastructure of the Netherlands has constructed an atlas of drug-metabolite associations for 87 commonly prescribed drugs and 150 clinically relevant plasma-based metabolites assessed by proton nuclear magnetic resonance. The atlas includes a meta-analysis of ten cohorts (18,873 persons) and uncovers 1,071 drug-metabolite associations after evaluation of confounders including co-treatment. We show that the effect estimates of statins on metabolites from the cross-sectional study are comparable to those from intervention and genetic observational studies. Further data integration links proton pump inhibitors to circulating metabolites, liver function, hepatic steatosis and the gut microbiome. Our atlas provides a tool for targeted experimental pharmaceutical research and clinical trials to improve drug efficacy, safety and repurposing. We provide a web-based resource for visualization of the atlas (http://bbmri.researchlumc.nl/atlas/).

Diesel Exhaust Induces Mitochondrial Dysfunction, Hyperlipidemia, and Liver Steatosis

OBJECTIVE

Air pollution is associated with increased cardiovascular morbidity and mortality, as well as dyslipidemia and metabolic syndrome. Our goal was to dissect the mechanisms involved. Approach and Results: We assessed the effects of exposure to air pollution on lipid metabolism in mice through assessment of plasma lipids and lipoproteins, oxidized fatty acids 9-HODE (9-hydroxyoctadecadienoic) and 13-HODE (13-hydroxyoctadecadienoic), lipid, and carbohydrate metabolism. Findings were corroborated, and mechanisms were further assessed in HepG2 hepatocytes in culture. ApoE knockout mice exposed to inhaled diesel exhaust (DE, 6 h/d, 5 days/wk for 16 weeks) exhibited elevated plasma cholesterol and triglyceride levels, increased hepatic triglyceride content, and higher hepatic levels of 9-HODE and 13-HODE, as compared to control mice exposed to filtered air. A direct effect of DE exposure on hepatocytes was demonstrated by treatment of HepG2 cells with a methanol extract of DE particles followed by loading with oleic acid. As observed in vivo, this led to increased triglyceride content and significant downregulation of ACAD9 mRNA expression. Treatment of HepG2 cells with DE particles and oleic acid did not alter de novo lipogenesis but inhibited total, mitochondrial, and ATP-linked oxygen consumption rate, indicative of mitochondrial dysfunction. Treatment of isolated mitochondria, prepared from mouse liver, with DE particles and oleic acid also inhibited mitochondrial complex activity and β-oxidation.

CONCLUSIONS

DE exposure leads to dyslipidemia and liver steatosis in ApoE knockout mice, likely due to mitochondrial dysfunction and decreased lipid catabolism.

Genetic Deletion or Pharmacological Inhibition of Soluble Epoxide Hydrolase Ameliorates Cardiac Ischemia/Reperfusion Injury by Attenuating NLRP3 Inflammasome Activation

Activation of the nucleotide-binding oligomerization domain-like receptor (NLR) family pyrin domain containing 3 (NLRP3) inflammasome cascade has a role in the pathogenesis of ischemia/reperfusion (IR) injury. There is growing evidence indicating cytochrome p450 (CYP450)-derived metabolites of n-3 and n-6 polyunsaturated fatty acids (PUFAs) possess both adverse and protective effects in the heart. CYP-derived epoxy metabolites are rapidly hydrolyzed by the soluble epoxide hydrolase (sEH). The current study hypothesized that the cardioprotective effects of inhibiting sEH involves limiting activation of the NLRP3 inflammasome. Isolated hearts from young wild-type (WT) and sEH null mice were perfused in the Langendorff mode with either vehicle or the specific sEH inhibitor t-AUCB. Improved post-ischemic functional recovery and better mitochondrial respiration were observed in both sEH null hearts or WT hearts perfused with t-AUCB. Inhibition of sEH markedly attenuated the activation of the NLRP3 inflammasome complex and limited the mitochondrial localization of the fission protein dynamin-related protein-1 (Drp-1) triggered by IR injury. Cardioprotective effects stemming from the inhibition of sEH included preserved activities of both cytosolic thioredoxin (Trx)-1 and mitochondrial Trx-2 antioxidant enzymes. Together, these data demonstrate that inhibiting sEH imparts cardioprotection against IR injury via maintaining post-ischemic mitochondrial function and attenuating a detrimental innate inflammatory response.

Up-regulation of 15-lipoxygenase enzymes and products in functional and non-functional pituitary adenomas

Background

Pituitary adenoma accounts as a complex and multifactorial intracranial neoplasm with wide range of clinical symptoms which its underlying molecular mechanism has yet to be determined. The bioactive lipid mediators received attentions toward their contribution in cancer cell proliferation, progression and death. Amongst, 15-Lipoxygense (15-Lox) enzymes and products display appealing role in cancer pathogenesis which their possible effect in pituitary adenoma tumor genesis is perused in the current study.

Methods

The 15-Lipoxygenses isoforms expression level was evaluated in tumor tissues of prevalent functional and non-functional pituitary adenomas and normal pituitary tissues via Real-Time PCR. The circulating levels of 15(S) HETE and 13(S) HODE as 15-Lox main products were assessed in serum of patients and healthy subjects using enzyme immunoassay kits.

Results

Our results revealed that 15-Lox-1 and 15-Lox-2 expression levels were elevated in tumor tissues of pituitary adenomas comparing to normal pituitary tissues. The elevated levels of both isoforms were accompanied with 15(S) HETE and 13(S) HODE elevation in the serum of patients. The 15-Lox-1 expression and activity was higher in invasive tumors as well as tumors with bigger size indicating the possible pro-tumorigenic role of 15-Lox-1, more than 15-Lox-2 in pituitary adenomas. The diagnostic value of 15-Lipoxygense isoforms and products were considerable between patients and healthy groups.

Conclusion

The possible involvement of 15-Lipoxygense pathway especially 15-Lox-1 in the regulation of pituitary tumor growth and progression may open up new molecular mechanism regarding pituitary adenoma pathogenesis and might shed light on its new therapeutic strategies.

Replacement of an Indole Scaffold Targeting Human 15-Lipoxygenase-1 Using Combinatorial Chemistry

Human 15-lipoxygenase-1 (15-LOX-1) belongs to the class of lipoxygenases, which catalyze oxygenation of polyunsaturated fatty acids, such as arachidonic and linoleic acid. Recent studies have shown that 15-LOX-1 plays an important role in physiological processes linked to several diseases such as airway inflammation disease, coronary artery disease, and several types of cancer such as rectal, colon, breast and prostate cancer. In this study, we aimed to extend the structural diversity of 15-LOX-1 inhibitors, starting from the recently identified indolyl core. In order to find new scaffolds, we employed a combinatorial approach using various aromatic aldehydes and an aliphatic hydrazide tail. This scaffold-hopping study resulted in the identification of the 3-pyridylring as a suitable replacement of the indolyl core with an inhibitory activity in the micromolar range (IC 50=16±6 μm) and a rapid and efficient structure-activity relationship investigation.

Deficiency of Soluble Epoxide Hydrolase Protects Cardiac Function Impaired by LPS-Induced Acute Inflammation

Lipopolysaccharide (LPS) is a bacterial wall endotoxin producing many pathophysiological conditions including myocardial inflammation leading to cardiotoxicity. Linoleic acid (18:2n6, LA) is an essential n-6 PUFA which is converted to arachidonic acid (20:4n6, AA) by desaturation and elongation via enzyme systems within the body. Biological transformation of PUFA through CYP-mediated hydroxylation, epoxidation, and allylic oxidation produces lipid mediators, which may be subsequently hydrolyzed to corresponding diol metabolites by soluble epoxide hydrolase (sEH). In the current study, we investigate whether inhibition of sEH, which alters the PUFA metabolite profile, can influence LPS induced cardiotoxicity and mitochondrial function. Our data demonstrate that deletion of soluble epoxide hydrolase provides protective effects against LPS-induced cardiotoxicity by maintaining mitochondrial function. There was a marked alteration in the cardiac metabolite profile with notable increases in sEH-derived vicinal diols, 9,10- and 12,13-dihydroxyoctadecenoic acid (DiHOME) in WT hearts following LPS administration, which was absent in sEH null mice. We found that DiHOMEs triggered pronounced mitochondrial structural abnormalities, which also contributed to the development of extensive mitochondrial dysfunction in cardiac cells. Accumulation of DiHOMEs may represent an intermediate mechanism through which LPS-induced acute inflammation triggers deleterious alterations in the myocardium in vivo and cardiac cells in vitro. This study reveals novel research exploring the contribution of DiHOMEs in the progression of adverse inflammatory responses toward cardiac function in vitro and in vivo.

Umbilical cord blood metabolomics reveal distinct signatures of dyslipidemia prior to bronchopulmonary dysplasia and pulmonary hypertension

Pulmonary hypertension (PH) is a common consequence of bronchopulmonary dysplasia (BPD) and remains a primary contributor to increased morbidity and mortality among preterm infants. Unfortunately, at the present time, there are no reliable early predictive markers for BPD-associated PH. Considering its health consequences, understanding in utero perturbations that lead to the development of BPD and BPD-associated PH and identifying early predictive markers is of utmost importance. As part of the discovery phase, we applied a multiplatform metabolomics approach consisting of untargeted and targeted methodologies to screen for metabolic perturbations in umbilical cord blood (UCB) plasma from preterm infants that did ( n = 21; cases) or did not ( n = 21; controls) develop subsequent PH. A total of 1,656 features were detected, of which 407 were annotated by metabolite structures. PH-associated metabolic perturbations were characterized by reductions in major choline-containing phospholipids, such as phosphatidylcholines and sphingomyelins, indicating altered lipid metabolism. The reduction in UCB abundances of major choline-containing phospholipids was confirmed in an independent validation cohort consisting of UCB plasmas from 10 cases and 10 controls matched for gestational age and BPD status. Subanalyses in the discovery cohort indicated that elevations in the oxylipins PGE1, PGE2, PGF2a, 9- and 13-HOTE, 9- and 13-HODE, and 9- and 13-KODE were positively associated with BPD presence and severity. This expansive evaluation of cord blood plasma identifies compounds reflecting dyslipidemia and suggests altered metabolite provision associated with metabolic immaturity that differentiate subjects, both by BPD severity and PH development.

Effects of diets enriched in linoleic acid and its peroxidation products on brain fatty acids, oxylipins, and aldehydes in mice

BACKGROUND

Linoleic acid (LA) is abundant in modern industrialized diets. Oxidized LA metabolites (OXLAMs) and reactive aldehydes, such as 4-hydroxy-2-nonenal (4-HNE), are present in heated vegetable oils and can be endogenously synthesized following consumption of dietary LA. OXLAMs have been implicated in cerebellar degeneration in chicks; 4-HNE is linked to neurodegenerative conditions in mammals. It unknown whether increasing dietary LA or OXLAMs alters the levels of oxidized fatty acids (oxylipins), precursor fatty acids, or 4-HNE in mammalian brain.

OBJECTIVES

To determine the effects of increases in dietary OXLAMs and dietary LA, on levels of fatty acids, oxylipins, and 4-HNE in mouse brain tissues.

METHODS

Mice (n = 8 per group) were fed one of three controlled diets for 8 weeks: (1) a low LA diet, (2) a high LA diet, or (3) the low LA diet with added OXLAMs. Brain fatty acids, oxylipins, and 4-HNE were quantified in mouse cerebellum and cerebral cortex by gas chromatography-flame ionization detection, liquid chromatography-tandem mass spectrometry, and immunoblot, respectively.

RESULTS

Increasing dietary LA significantly increased omega-6 fatty acids, decreased omega-3 fatty acids, and increased OXLAMs in brain. Dietary OXLAMs had minimal effect on oxidized lipids but did decrease both omega-6 and omega-3 fatty acids. Neither dietary LA nor OXLAMs altered 4-HNE levels.

CONCLUSION

Brain fatty acids are modulated by both dietary LA and OXLAMs, while brain OXLAMs are regulated by endogenous synthesis from LA, rather than incorporation of preformed OXLAMs.

Reduction in polyamine catabolism leads to spermine-mediated airway epithelial injury and induces asthma features

BACKGROUND

Airway epithelial injury is a crucial component of acute and severe asthma pathogenesis and a promising target for treatment of refractory asthma. However, the underlying mechanism of epithelial injury remains poorly explored. Although high levels of polyamines, mainly spermine, have been found in asthma and comorbidity, their role in airway epithelial injury and the cause of their altered levels in asthma have not been explored.

METHODS

We measured key polyamine metabolic enzymes in lung samples from normal and asthmatic subjects and in mice with OVA-induced allergic airway inflammation (AAI). Polyamine metabolism was modulated using pharmacologic/genetic modulators. Epithelial stress and apoptosis were measured by TSLP levels and TUNEL assay, respectively.

RESULTS

We found loss of the polyamine catabolic enzymes spermidine/spermine-N (1)-acetyltransferase-1 (SAT1) and spermine oxidase (SMOX) predominantly in bronchial epithelial cells (BECs) of human asthmatic lung samples and mice with AAI. In naïve mice, SAT1 or SMOX knockdown led to airway hyper-responsiveness, remodeling, and BEC apoptosis. Conversely, in mice with AAI, overexpression of either SAT1 or SMOX alleviated asthmatic features and reduced TSLP levels and BEC apoptosis. Similarly, while pharmacological induction of SAT1 and SMOX using the polyamine analogue bis(ethyl)norspermine (BENSPM) alleviated asthmatic features with reduced TSLP levels and BEC apoptosis, pharmacological inhibition of these enzymes using BERENIL or MDL72527, respectively, worsened them. Spermine accumulation in lungs correlated with BEC apoptosis, and spermine treatment caused apoptosis of human BEAS-2B cells in vitro.

CONCLUSIONS

Spermine induces BEC injury. Induction of polyamine catabolism may represent a novel therapeutic approach for asthma via reversing BEC stress.

Vaginal lipidomics of women with vulvovaginal candidiasis and cytolytic vaginosis: A non-targeted LC-MS pilot study

Objective

To characterize the lipid profile in vaginal discharge of women with vulvovaginal candidiasis, cytolytic vaginosis, or no vaginal infection or dysbiosis.

Design

Cross-sectional study.

Setting

Genital Infections Ambulatory, Department of Tocogynecology, University of Campinas, Campinas, São Paulo–Brazil.

Sample

Twenty-four women were included in this study: eight with vulvovaginal candidiasis, eight with cytolytic vaginosis and eight with no vaginal infections or dysbiosis (control group).

Methods

The lipid profile in vaginal discharge of the different study groups was determined by liquid chromatography-mass spectrometry and further analyzed with MetaboAnalyst 3.0 platform.

Main outcome measures

Vaginal lipids concentration and its correlation with vulvovaginal candidiasis and cytolytic vaginosis.

Results

PCA, PLS-DA and hierarchical clustering analyses indicated 38 potential lipid biomarkers for the different groups, correlating with oxidative stress, inflammation, apoptosis and integrity of the vaginal epithelial tissue. Among these, greater concentrations were found for Glycochenodeoxycholic acid-7-sulfate, O-adipoylcarnitine, 1-eicosyl-2-heptadecanoyl-glycero-3-phosphoserine, undecanoic acid, formyl dodecanoate and lipoic acid in the vulvovaginal candidiasis group; N–(tetradecanoyl)-sphinganine, DL-PPMP, 1-oleoyl-cyclic phosphatidic, palmitic acid and 5-aminopentanoic acid in the cytolytic vaginosis group; and 1-nonadecanoyl-glycero-3-phosphate, eicosadienoic acid, 1-stearoyl-cyclic-phosphatidic acid, 1-(9Z,12Z-heptadecadienoyl)-glycero-3-phosphate, formyl 9Z-tetradecenoate and 7Z,10Z-hexadecadienoic acid in the control group.

Conclusions

Lipids related to oxidative stress and apoptosis were found in higher concentrations in women with vulvovaginal candidiasis and cytolytic vaginosis, while lipids related to epithelial tissue integrity were more pronounced in the control group. Furthermore, in women with cytolytic vaginosis, we observed higher concentrations of lipids related to bacterial overgrowth.

Delayed gut microbiota development in high-risk for asthma infants is temporarily modifiable by Lactobacillus supplementation

Gut microbiota dysbiosis and metabolic dysfunction in infancy precedes childhood atopy and asthma development. Here we examined gut microbiota maturation over the first year of life in infants at high risk for asthma (HR), and whether it is modifiable by early-life Lactobacillus supplementation. We performed a longitudinal comparison of stool samples collected from HR infants randomized to daily oral Lactobacillus rhamnosus GG (HRLGG) or placebo (HRP) for 6 months, and healthy (HC) infants. Meconium microbiota of HRP participants is distinct, follows a delayed developmental trajectory, and is primarily glycolytic and depleted of a range of anti-inflammatory lipids at 6 months of age. These deficits are partly rescued in HRLGG infants, but this effect was lost at 12 months of age, 6 months after cessation of supplementation. Thus we show that early-life gut microbial development is distinct, but plastic, in HR infants. Our findings offer a novel strategy for early-life preventative interventions.

Gut microbial dysbiosis in infancy is associated with childhood atopy and the development of asthma. Here, the authors show that gut microbiota perturbation is evident in the very earliest stages of postnatal life, continues throughout infancy, and can be partially rescued by Lactobacillus supplementation in high-risk for asthma infants.

Dietary Linoleic Acid and Its Oxidized Metabolites Exacerbate Liver Injury Caused by Ethanol via Induction of Hepatic Proinflammatory Response in Mice

Alcoholic liver disease is a major human health problem leading to significant morbidity and mortality in the United States and worldwide. Dietary fat plays an important role in alcoholic liver disease pathogenesis. Herein, we tested the hypothesis that a combination of ethanol and a diet rich in linoleic acid (LA) leads to the increased production of oxidized LA metabolites (OXLAMs), specifically 9- and 13-hydroxyoctadecadienoic acids (HODEs), which contribute to a hepatic proinflammatory response exacerbating liver injury. Mice were fed unsaturated (with a high LA content) or saturated fat diets (USF and SF, respectively) with or without ethanol for 10 days, followed by a single binge of ethanol. Compared to SF+ethanol, mice fed USF+ethanol had elevated plasma alanine transaminase levels, enhanced hepatic steatosis, oxidative stress, and inflammation. Plasma and liver levels of 9- and 13-HODEs were increased in response to USF+ethanol feeding. We demonstrated that primarily 9-HODE, but not 13-HODE, induced the expression of several proinflammatory cytokines in vitro in RAW264.7 macrophages. Finally, deficiency of arachidonate 15-lipoxygenase, a major enzyme involved in LA oxidation and OXLAM production, attenuated liver injury and inflammation caused by USF+ethanol feeding but had no effect on hepatic steatosis. This study demonstrates that OXLAM-mediated induction of a proinflammatory response in macrophages is one of the potential mechanisms underlying the progression from alcohol-induced steatosis to alcoholic steatohepatitis.

Mediating Role of TRPV1 Ion Channels in the Co-exposure to PM2.5 and Formaldehyde of Balb/c Mice Asthma Model

Asthma is a complex pulmonary inflammatory disease that can be promoted by air pollutants such as PM2.5 and formaldehyde (FA). However, existent experimental evidence principally focuses on the negative influence of a single air pollutant, neglecting the possible synergistic effect in biological responses to mixture of these pollutants, a more common situation in our daily life. In this study, allergic Balb/c mice were exposed to a mixture of PM2.5 and FA, and their toxicological effects and mechanisms were explored. It is demonstrated that the combined exposure to PM2.5 and FA can greatly aggravate allergic asthma in mice. When compared with exposure to PM2.5 or FA alone, the co-exposure showed a certain synergistic effect. Increased levels of ROS, inflammatory factors and total serum immunoglobulin E were concomitant with this deterioration. Furthermore, results suggested that co-exposure exacerbated the activation of TRPV1 signal pathways, with an enhancement in substance P and calcitonin gene-related peptide production, which contributed to inflammation in asthma by neurogenic inflammation. The study also proved that capsazepine treatment could reduce the levels of not only pro-inflammatory neuropeptides, but also oxidative stress. It is concluded that co-exposure to PM2.5 and FA exacerbated allergic asthma through oxidative stress and enhanced TRPV1 activation.

Lipoxygenase Activity Accelerates Programmed Spore Germination in Aspergillus fumigatus

The opportunistic human pathogen Aspergillus fumigatus initiates invasive growth through a programmed germination process that progresses from dormant spore to swollen spore (SS) to germling (GL) and ultimately invasive hyphal growth. We find a lipoxygenase with considerable homology to human Alox5 and Alox15, LoxB, that impacts the transitions of programmed spore germination. Overexpression of loxB (OE::loxB) increases germination with rapid advance to the GL stage. However, deletion of loxB (ΔloxB) or its signal peptide only delays progression to the SS stage in the presence of arachidonic acid (AA); no delay is observed in minimal media. This delay is remediated by the addition of the oxygenated AA oxylipin 5-hydroxyeicosatetraenoic acid (5-HETE) that is a product of human Alox5. We propose that A. fumigatus acquisition of LoxB (found in few fungi) enhances germination rates in polyunsaturated fatty acid-rich environments.

The Phosphatidylcholine Transfer Protein Stard7 is Required for Mitochondrial and Epithelial Cell Homeostasis

Mitochondria synthesize select phospholipids but lack the machinery for synthesis of the most abundant mitochondrial phospholipid, phosphatidylcholine (PC). Although the phospholipid transfer protein Stard7 promotes uptake of PC by mitochondria, the importance of this pathway for mitochondrial and cellular homeostasis represents a significant knowledge gap. Haploinsufficiency for Stard7 is associated with significant exacerbation of allergic airway disease in mice, including an increase in epithelial barrier permeability. To test the hypothesis that Stard7 deficiency leads to altered barrier structure/function downstream of mitochondrial dysfunction, Stard7 expression was knocked down in a bronchiolar epithelial cell line (BEAS-2B) and specifically deleted in lung epithelial cells of mice (Stard7^epi∆/∆). Stard7 deficiency was associated with altered mitochondrial size and membrane organization both in vitro and in vivo. Altered mitochondrial structure was accompanied by disruption of mitochondrial homeostasis, including decreased aerobic respiration, increased oxidant stress, and mitochondrial DNA damage that, in turn, was linked to altered barrier integrity and function. Both mitochondrial and barrier defects were largely corrected by targeting Stard7 to mitochondria or treating epithelial cells with a mitochondrial-targeted antioxidant. These studies suggest that Stard7-mediated transfer of PC is crucial for mitochondrial homeostasis and that mitochondrial dysfunction contributes to altered barrier permeability in Stard7-deficient mice.