Nitro-oleic Acid Research Articles

Adipocyte-specific Nrf2 deletion negates nitro-oleic acid benefits on glucose tolerance in diet-induced obesity

Obesity is commonly linked with white adipose tissue (WAT) dysfunction, setting off inflammation and oxidative stress, both key contributors to the cardiometabolic complications associated with obesity. To improve metabolic and cardiovascular health, countering these inflammatory and oxidative signaling processes is crucial. Offering potential in this context, the activation of nuclear factor erythroid 2-related factor 2 (Nrf2) by nitro-fatty acids (NO2-FA) promote diverse anti-inflammatory signaling and counteract oxidative stress. Additionally, we previously highlighted that nitro-oleic acid (NO2-OA) preferentially accumulates in WAT and provides protection against already established high fat diet (HFD)-mediated impaired glucose tolerance. The precise mechanism accounting for these protective effects remained largely unexplored until now. Herein, we reveal that protective effects of improved glucose tolerance by NO2-OA is absent when Nrf2 is specifically ablated in adipocytes (ANKO mice). NO2-OA treatment did not alter body weight between ANKO and littermate controls (Nrf2fl/fl) mice on both the HFD and low-fat diet (LFD). As expected, at day 76 (before NO2-OA treatment) and notably at day 125 (daily treatment of 15 mg/kg NO2-OA for 48 days), both HFD-fed Nrf2fl/fl and ANKO mice exhibited increased fat mass and reduced lean mass compared to LFD controls. However, throughout the NO2-OA treatment, no distinction was observed between Nrf2fl/fl and ANKO in the HFD-fed mice as well as in the Nrf2fl/fl mice fed a LFD. Glucose tolerance tests revealed impaired glucose tolerance in HFD-fed Nrf2fl/fl and ANKO compared to LFD-fed Nrf2fl/fl mice. Notably, NO2-OA treatment improved glucose tolerance in HFD-fed Nrf2fl/fl but did not yield the same improvement in ANKO mice at days 15, 30, and 55 of treatment. Unraveling the pathways linked to NO2-OA's protective effects in obesity-mediated impairment in glucose tolerance is pivotal within the realm of precision medicine, crucially propelling future applications and refining novel drug-based strategies.

Enabling non-viral DNA delivery using lipid nanoparticles co-loaded with endogenous anti-inflammatory lipids.

Lipid nanoparticles (LNPs) have transformed genetic medicine, recently shown by their use in COVID-19 mRNA vaccines. While loading LNPs with mRNA has many uses, loading DNA would provide additional advantages such as long-term expression and availability of promoter sequences. However, here we show that plasmid DNA (pDNA) delivery via LNPs (pDNA-LNPs) induces acute inflammation in naïve mice which we find is primarily driven by the cGAS-STING pathway. Inspired by DNA viruses that inhibit this pathway for replication, we co-loaded endogenous lipids that inhibit STING into pDNA-LNPs. Specifically, loading nitro-oleic acid (NOA) into pDNA-LNPs (NOA-pDNA-LNPs) ameliorates serious inflammatory responses in vivo enabling prolonged transgene expression (at least 1 month). Additionally, we demonstrate the ability to iteratively optimize NOA-pDNA-LNPs' expression by performing a small LNP formulation screen, driving up expression 50-fold in vitro . Thus, NOA-pDNA-LNPs, and pDNA-LNPs co-loaded with other bioactive molecules, will provide a major new tool in the genetic medicine toolbox, leveraging the power of DNA's long-term and promoter-controlled expression.

Targeting mitochondrial biogenesis with nitro-oleic acid has protective effects on murine cardiomyocytes under metabolic stress

Targeting mitochondrial biogenesis with nitro-oleic acid has protective effects on murine cardiomyocytes under metabolic stress

20-HETE As an Emerging Target to Improve Renal Health in Sickle Cell Disease

The kidney is one of the most severely affected organs in sickle cell disease (SCD), with glomerular hyperfiltration and microalbuminuria beginning in childhood, and progressing to chronic kidney disease (CKD) in majority of adults. Sickle individuals also suffer from acute kidney injury (AKI) often during characteristic vaso-occlusive crisis. Renal pathology in sickle cell nephropathy includes extensive microvascular congestions and thrombotic microangiopathy. The hypercoagulable and vasoconstrictive environment of SCD, in conjunction with medullary hypoperfusion and cortical hyperperfusion contributes to vaso-occlusive injury and deregulates intrarenal hemostasis leading to CKD development. Ischemic injury increases arachidonic acid hydroxylation producing 20-hydroxyeicosatetraenoic acid (20-HETE), which in turn triggers thrombosis and promotes vasoconstriction in the kidney. However, the role of 20-HETE in regulating renal hemostasis in SCD nephropathy has never been reported. We found that plasma 20-HETE is significantly elevated in SCD patients (n=9-11; p<0.01) compared to normal individuals. Similarly, transgenic SCD mice (SS), homozygous for human hemoglobin S, have increased plasma 20-HETE compared to control mice (AA), homozygous for human hemoglobin A (n=6; p<0.01). We have previously shown that elevated circulating heme mimicking hemolytic crisis triggers clinically relevant acute kidney injury (AKI) in SS mice (Blood (2020) 135(13): 1044-1048). We postulated that hemolytic stress may exacerbate 20-HETE production which in turn aggravates renal microvascular occlusion and vasoconstriction, leading to renal damage in SCD. Immunohistochemistry and biochemical experiments showed that the expression of CYP4A12a, a cytochrome 450-dependent enzyme responsible 20-HETE production in mice, is substantially elevated in the kidneys of SS mice compared to AA mice, associated with increased vascular congestion and renal thrombogenesis. Renal CYP4A12a and plasma 20-HETE were increased substantially following heme-induced AKI in SS mice, associated with a heightened expression of renal angiotensin II receptor 1 (ATIIR1), thus indicating induced vasoconstrictive activity. In vitro, we found that 20-HETE induced ATIIR1 expression in human renal glomerular endothelial cells (hRGEC), which was further exacerbated by low-concentration of heme challenge (5 mM for 24 hour). Nitro-oleic acid (NO 2-OA) is a nitrated fatty acid that binds ATIIR1 and inhibits angiotensin II induced vasoconstriction. Pretreatment with NO 2-OA reduced 20-HETE-dependent ATIIR1 expression in hRGEC, while NO 2-OA prophylaxis during hemin-induced AKI inhibited albuminuria, normalized plasma creatinine levels, and lowered the expression of ATIIR1 in SS mice kidneys. Overall, our data show that elevated 20-HETE levels during hemolytic stress may aggravate renal injury in SCD which can be prevented by NO 2-OA prophylaxis. Ongoing experiments will determine the direct effect of elevated 20-HETE in renal hemostasis and CKD development in SCD.

Nitro-oleic acid attenuates pro-inflammatory metabolic signaling in LPS activated macrophages

Nitro-oleic acid attenuates pro-inflammatory metabolic signaling in LPS activated macrophages

Cell-type specific anti-cancerous effects of nitro-oleic acid and its combination with gamma irradiation.

Nitro-fatty acids (NFAs) are endogenous lipid mediators capable of post-translational modifications of selected regulatory proteins. Here, we investigated the anti-cancerous effects of nitro-oleic acid (NO2OA) and its combination with gamma irradiation on different cancer cell lines. The effects of NO2OA on cell death, cell cycle distribution, or expression of p21 and cyclin D1 proteins were analyzed in cancer (A-549, HT-29 and FaDu) or normal cell lines (HGF, HFF-1). Dose enhancement ratio at 50 % survival fraction (DERIC50) was calculated for samples pre-treated with NO2OA followed by gamma irradiation. NO2OA suppressed viability and induced apoptotic cell death. These effects were cell line specific but not in general selective for cancer cells. HT-29 cell line exerted higher sensitivity toward NO2OA treatment among cancer cell lines tested: induction of cell cycle arrest in the G2/M phase was associated with an increase in p21 and a decrease in cyclin D1 expression. Pre-treatment of HT-29 cells with NO2OA prior irradiation showed a significantly increased DERIC50, demonstrating radiosensitizing effects. In conclusion, NO2OA exhibited potential for combined chemoradiotherapy. Our results encourage the development of new NFAs with improved features for cancer chemoradiation.

Nitro-oleic acid ameliorates erectile dysfunction in a streptozotocin-induced rat model of diabetes by inhibiting oxidative stress and apoptosis and activating the NO/cGMP pathway.

The major vascular complications associated with diabetes make the management of diabetic mellitus erectile dysfunction (DMED) a challenging endeavor. Notable factors contributing to DMED include oxidative stress, nitric oxide (NO)/cyclic guanosine monophosphate (cGMP) pathway activation, and apoptosis, while nitro-oleic acid (NO 2 -OA) has been shown to be beneficial in treating these aspects of this condition. We, herein, investigated the effects and possible mechanisms of NO 2 -OA on erectile function as assessed in a streptozotocin-induced rat model of diabetes. Our results revealed that the erectile function of DMED rats was significantly impaired compared with that of the control group. However, in response to 4 weeks of NO 2 -OA treatment, there was an improvement in erectile function. The expression of oxidative stress-related indicators was significantly increased and the NO/cGMP pathway was impaired in the DMED group. The expression of proapoptotic factors was increased, while that of antiapoptotic factors was decreased in the DMED group. Moreover, the cell morphology in the cavernous tissue of the DMED group also changed adversely. NO 2 -OA treatment significantly reversed all these changes observed in the DMED group. In conclusion, NO 2 -OA treatment partially improved erectile function in DMED rats through mechanisms that included inhibition of oxidative stress, activation of the NO/cGMP pathway, and a reduction in apoptosis.

Preparation, stability, and molecular modeling of nitro-oleic acid/cyclodextrin complexes under aqueous conditions

Nitro-oleic acid (NO2-OA) is an endogenously produced pleiotropic modulator involved in cell redox homeostasis. The intrinsic property of NO2-OA is a decay reaction under aqueous conditions. This aqueous instability is simultaneously a problematic issue for NO2-OA sample handling and NO2-OA application in general. In this work NO2-OA (eq. mol. 9/10-NO2 isomers) was encapsulated with β-cyclodextrin (β-CD). The formation of the β-CD/NO2-OA complex was determined based on 1H NMR. The QM calculations revealed that dispersion forces are crucial for the stability of the complex. Based on thermogravimetry–differential scanning calorimetry, free NO2-OA was less thermally stable than its inclusion β-CD complex. The electrochemical reduction of the nitro group was investigated to determine the degradation kinetics of β-CD/NO2-OA. Under aqueous conditions, β-CD/NO2-OA degrades at a similar rate to NO2-OA alone. However, when β-CD/NO2-OA is stored in solid (lyophilized) form, no degradation was observed for a one-month period.

Meta-omics profiling of the gut-lung axis illuminates metabolic networks and host-microbial interactions associated with elevated lung elastance in a murine model of obese allergic asthma.

Obesity and associated changes to the gut microbiome worsen airway inflammation and hyperresponsiveness in asthma. Obesogenic host-microbial metabolomes have altered production of metabolites that may influence lung function and inflammatory responses in asthma. To understand the interplay of the gut microbiome, metabolism, and host inflammation in obesity-associated asthma, we used a multi-omics approach to profile the gut-lung axis in the setting of allergic airway disease and diet-induced obesity. We evaluated an immunomodulator, nitro-oleic acid (NO2-OA), as a host- and microbial-targeted treatment intervention for obesity-associated allergic asthma. Allergic airway disease was induced using house dust mite and cholera toxin adjuvant in C57BL6/J mice with diet-induced obesity to model obesity-associated asthma. Lung function was measured by flexiVent following a week of NO2-OA treatment and allergen challenge. 16S rRNA gene (from DNA, taxa presence) and 16S rRNA (from RNA, taxa activity) sequencing, metabolomics, and host gene expression were paired with a Treatment-Measured-Response model as a data integration framework for identifying latent/hidden relationships with linear regression among variables identified from high-dimensional meta-omics datasets. Targeting both the host and gut microbiota, NO2-OA attenuated airway inflammation, improved lung elastance, and modified the gut microbiome. Meta-omics data integration and modeling determined that gut-associated inflammation, metabolites, and functionally active gut microbiota were linked to lung function outcomes. Using Treatment-Measured-Response modeling and meta-omics profiling of the gut-lung axis, we uncovered a previously hidden network of interactions between gut levels of amino acid metabolites involved in elastin and collagen synthesis, gut microbiota, NO2-OA, and lung elastance. Further targeted metabolomics analyses revealed that obese mice with allergic airway disease had higher levels of proline and hydroxyproline in the lungs. NO2-OA treatment reduced proline biosynthesis by downregulation of pyrroline-5-carboxylate reductase 1 (PYCR1) expression. These findings are relevant to human disease: adults with mild-moderate asthma and BMI ≥ 25 had higher plasma hydroxyproline levels. Our results suggest that changes to structural proteins in the lung airways and parenchyma may contribute to heightened lung elastance and serve as a potential therapeutic target for obese allergic asthma.

Nitro-oleic acid modulates redox regulation in isolated murine cardiomyocytes

Nitro-oleic acid modulates redox regulation in isolated murine cardiomyocytes

Protective Effect of NO2-OA on Oxidative Stress, Gliosis, and Pro-Angiogenic Response in Müller Glial Cells.

Inflammation and oxidative and nitrosative stress are involved in the pathogenesis of proliferative retinopathies (PR). In PR, a loss of balance between pro-angiogenic and anti-angiogenic factors favors the secretion of vascular endothelial growth factor (VEGF). This vascular change results in alterations in the blood-retinal barrier, with extravasation of plasma proteins such as α2-macroglobulin (α2M) and gliosis in Müller glial cells (MGCs, such as MIO-M1). It is well known that MGCs play important roles in healthy and sick retinas, including in PR. Nitro-fatty acids are electrophilic lipid mediators with anti-inflammatory and cytoprotective properties. Our aim was to investigate whether nitro-oleic acid (NO2-OA) is beneficial against oxidative stress, gliosis, and the pro-angiogenic response in MGCs. Pure synthetic NO2-OA increased HO-1 expression in a time- and concentration-dependent manner, which was abrogated by the Nrf2 inhibitor trigonelline. In response to phorbol 12-myristate 13-acetate (PMA) and lipopolysaccharide (LPS), NO2-OA prevented the ROS increase and reduced the gliosis induced by α2M. Finally, when hypoxic MGCs were incubated with NO2-OA, the increase in VEGF mRNA expression was not affected, but under hypoxia and inflammation (IL-1β), NO2-OA significantly reduced VEGF mRNA levels. Furthermore, NO2-OA inhibited endothelial cell (BAEC) tubulogenesis. Our results highlight NO2-OA's protective effect on oxidative damage, gliosis; and the exacerbated pro-angiogenic response in MGCs.

Development and Validation of a Bioanalytical Method for the Quantification of Nitrated Fatty Acids in Plasma Using LC-MS/MS: Application to Cardiovascular Patients

Nitrated fatty acids (NO2-FAs) are a newly discovered class of biologically active compounds with distinct biochemical features that induce physiologically beneficial alterations in transcriptional regulatory protein function, leading to a variety of modulatory and protective actions. The most common NO2-FAs identified in vivo so far are nitro oleic acid (NO2-OA), nitro linoleic acid (NO2-LA) and its structural isomer nitro-conjugated linoleic acid (NO2-cLA). Analytical limitations that compromise accurate quantitation of these endogenous compounds are their low concentrations, compromised stability and different distribution profiles in tissues and biofluids. As a result, reliable analytical methods for the quantitative determination of their endogenous levels are rare. Only NO2-OA was quantified by GC-MS while LC-MS methods are still scarce. In this work, an LC-MS/MS bioanalytical method was developed and validated for the quantification of NO2-OA and NO2-LA in human plasma via a standard addition protocol after protein precipitation, liquid extraction and LC-MS/MS analysis in the negative ion mode. Quantification was performed via multiple reaction monitoring of the transitions m/z 326 > 46 and m/z 324 > 46 for NO2-OA and NO2-LA, respectively, and m/z 269 > 250 for the internal standard heptadecanoic acid. Linear responses were observed for both analytes over the studied range (R2 = 0.9805 and 0.9644 for NO2-OA and NO2-LA, respectively). Sufficient accuracy and precision were also achieved at low, medium and high levels within the linearity range. The limits of quantification of our method (2 nM for both NO2-FAs) were below basal endogenous levels, thereby providing a good tool to accurately measure these NO2-FAs in plasma. We applied the validated method to compare NO2-OA and NO2-LA levels in the plasma of 28 ischemic heart disease (IHD) patients and 18 healthy controls. The levels of NO2-OA were found to be significantly higher in the plasma of patients (21.7 ± 9.8 nM) versus healthy controls (12.6 ± 6 nM) (p-value < 0.01). Whereas the levels of NO2-LA were comparable in both groups (3 ± 1 nM in patients, 3.2 ± 1.7 nM in controls, p-value = 0.87288). The early elevation of NO2-OA in plasma samples, which were collected 2–3 h post myocardial injury, implies the potential use of NO2-OA levels as a biomarker for IHD after further investigation with a larger number of IHD patients. To our knowledge, this is the first comparative study on the levels of NO2-FAs in humans with and without IHD.

Nitro-oleic acid regulates T cell activation through post-translational modification of calcineurin

Nitro-fatty acids (NO2-FAs) are unsaturated fatty acid nitration products that exhibit anti-inflammatory actions in experimental mouse models of autoimmune and allergic diseases. These electrophilic molecules interfere with intracellular signaling pathways by reversible post-translational modification of nucleophilic amino-acid residues. Several regulatory proteins have been identified as targets of NO2-FAs, modifying their activity and promoting gene expression changes that result in anti-inflammatory effects. Herein, we report the effects of nitro-oleic acid (NO2-OA) on pro-inflammatory T cell functions, showing that 9- and 10-NOA, but not their oleic acid precursor, decrease T cell proliferation, expression of activation markers CD25 and CD71 on the plasma membrane, and IL-2, IL-4, and IFN-γ cytokine gene expressions. Moreover, we have found that NO2-OA inhibits the transcriptional activity of nuclear factor of activated T cells (NFAT) and that this inhibition takes place through the regulation of the phosphatase activity of calcineurin (CaN), hindering NFAT dephosphorylation, and nuclear translocation in activated T cells. Finally, using mass spectrometry-based approaches, we have found that NO2-OA nitroalkylates CaNA on four Cys (Cys129, 228, 266, and 372), of which only nitroalkylation on Cys372 was of importance for the regulation of CaN phosphatase activity in cells, disturbing functional CaNA/CaNB heterodimer formation. These results provide evidence for an additional mechanism by which NO2-FAs exert their anti-inflammatory actions, pointing to their potential as therapeutic bioactive lipids for the modulation of harmful T cell-mediated immune responses.

Nitro-oleic acid (NO2-OA) ameliorates erectile dysfunction in a rat model of diabetes mellitus via modulation of fibrosis, inflammation and autophagy.

Inflammation, fibrosis and autophagy represent closely related factors associated with the pathogenesis of diabetes mellitus erectile dysfunction (DMED). In this study, the therapeutic effect of nitro-oleic acid (NO2-OA) in a streptozotocin-induced rat model of DMED was evaluated. Sixty rats were randomly divided into four groups: control, DMED, DMED + Vehicle and DMED + NO2-OA. DMED was induced by intraperitoneal injection of streptozotocin in male rats. Blood glucose and body weight were measured every 2 weeks. After 4 weeks of NO2-OA treatment, erectile function was measured by electrical stimulation of cavernous nerve (CN). Western blotting, quantitative real-time polymerase chain reaction (qRT-PCR), enzyme-linked immunosorbent assay (ELISA), immunofluorescence and Masson's trichrome staining were used to verify the related factors and protein expression levels. We found that NO2-OA could significantly increase erectile pressure in the corpus cavernosum of DMED rats. Results of western blot, confocal immunofluorescence and qRT-PCR assays revealed that NO2-OA significantly reduced inflammatory factors and the expression of nuclear factor kappa B (NF-κB). In addition, Masson staining results indicated that NO2-OA significantly reduced the display of fibrotic tissue in the corpus cavernosum. These beneficial effects may be related to reductions in the expression of transforming growth factor-β1 (TGF-β1) and connective tissue growth factor (CTGF) and the increase in the expression of α-smooth muscle actin (α-SMA). Finally, NO2-OA treatment increased the expression of the autophagy marker, LC3, while P62 was decreased, effects suggesting that one of the underlying mechanisms of NO2-OA may involve an activation of the PI3K/AKT/mTOR pathway to enhance the capacity for autophagy within this tissue. NO2-OA enhances erectile function within a rat model of DMED by inhibiting inflammation and fibrosis along with activating autophagy.

Administration of nitro-oleic acid mitigates radiation-induced hematopoietic injury in mice

AimsLimited number of agents that provide protection against hematopoietic acute radiation syndrome led us to the evaluation of nitro-oleic acid (NO2OA) as a potential protector/mitigator against radiation-induced hematopoietic injury in C57/BL6 mice. Materials and methodsNO2OA was administered before and after sub-lethal total body irradiation (TBI) and hematological parameters were evaluated 3 or 7 days after TBI. Key findingsOur results show that NO2OA significantly increase bone marrow cellularity including the granulocyte-macrophage colony-forming cells and erythroid progenitors on the 3rd day after TBI. In addition, NO2OA enhanced recovery of white blood cells (lymphocytes, neutrophils, and monocytes) in peripheral blood 7 days after irradiation. These effects may be in part attributed to NO2OA-induced granulocyte colony-stimulating factor production after TBI. On the other hand, radiation-induced impairment of peripheral red blood cells, hemoglobin, and platelets were not affected with NO2OA treatment up to 7 days post TBI. SignificanceIn conclusion, our data show that NO2OA significantly protects hematopoiesis after irradiation, and thus showed a high potential to act as an agent for medical radiation countermeasure.

Nitrated Fatty-Acids Distribution in Storage Biomolecules during Arabidopsis thaliana Development.

The non-enzymatic interaction of polyunsaturated fatty acids with nitric oxide (NO) and derived species results in the formation of nitrated fatty acids (NO2-FAs). These signaling molecules can release NO, reversibly esterify with complex lipids, and modulate protein function through the post-translational modification called nitroalkylation. To date, NO2-FAs act as signaling molecules during plant development in plant systems and are involved in defense responses against abiotic stress conditions. In this work, the previously unknown storage biomolecules of NO2-FAs in Arabidopsis thaliana were identified. In addition, the distribution of NO2-FAs in storage biomolecules during plant development was determined, with phytosterol esters (SE) and TAGs being reservoir biomolecules in seeds, which were replaced by phospholipids and proteins in the vegetative, generative, and senescence stages. The detected esterified NO2-FAs were nitro-linolenic acid (NO2-Ln), nitro-oleic acid (NO2-OA), and nitro-linoleic acid (NO2-LA). The last two were detected for the first time in Arabidopsis. The levels of the three NO2-FAs that were esterified in both lipid and protein storage biomolecules showed a decreasing pattern throughout Arabidopsis development. Esterification of NO2-FAs in phospholipids and proteins highlights their involvement in both biomembrane dynamics and signaling processes, respectively, during Arabidopsis plant development.

Oleic and nitro-oleic acid behavior at an electrified water-1,2-dichloroethane interface

In this work, oleic and 9/10-nitro oleic acid were studied at a polarized water-1,2-dichloroethane interface. We found that both fatty acids can undergo a simple interfacial ion transfer reaction that is mainly limited by diffusion. The possibility of spontaneous partitioning of the fatty acid into the organic phase and acting as a ligand for the facilitated sodium ion transfer was excluded. The ionic currents originating from the chemical species interfacial transfer were recorded starting from a pH of around 8.5, which agreed with their poor acidity. The acid-base properties of fatty acids were studied with pKa 9.7 (for oleic acid) and 8.5 for the 9/10-nitro derivative. The formal Galvani potential difference of the fatty acids ion transfer reaction was used to calculate the water-1,2-dichloroethane partition coefficients. The results indicated similar water solubility for 9/10-nitro oleic acid (logP' −3.47) and oleic acid (logP' −3.42), where 9/10-nitro oleic acid is slightly more hydrophilic. The partial water solubility of the fatty acids was confirmed by the measurement of ionic currents, which did not increase linearly with their increasing aqueous phase concentration. The obtained results were correlated with the dynamic light scattering of the fatty acids, indicating the formation of supramolecular structures. 9/10-Nitro oleic acid is an endogenously produced signaling molecule involved in cell redox homeostasis. The results obtained here could contribute to further (bio)chemical studies on fatty acid nitroalkenes.

Nitrooleic acid inhibits macrophage activation induced by lipopolysaccharide from Prevotella intermedia

The hypothesis of the present study was that nitro-fatty acids (NO2-FAs) would suppress inflammation associated with periodontal disease. To test this hypothesis, we investigated the influence of nitrooleic acid, a prototypical NO2-FA, on the inflammatory response of murine macrophages activated with lipopolysaccharide (LPS) from Prevotella intermedia, a pathogen associated the etiology of different types of periodontal diseases. LPS was prepared from P. intermedia cells by using phenol-water protocol. Culture supernatants were assayed for nitric oxide (NO), interleukin-1β (IL-1β), and IL-6. Real-time polymerase chain reaction and immunoblotting analyses were performed to quantify messenger RNA and protein expression, respectively. The secreted embryonic alkaline phosphatase reporter assay was performed to measure NF-κB activation. The transcription factor assay kit was used to measure DNA-binding of NF-κB subunits. Findings obtained from the present study revealed that nitrooleic acid suppresses the generation and messenger RNA expression of inducible NO synthase-derived NO, IL-1β, and IL-6 in RAW264.7 cells activated with P. intermedia LPS and promotes macrophage polarization toward anti-inflammatory M2 phenotype. We also found that nitrooleic acid exerts its effect via heme oxygenase-1 induction and suppression of NF-κB signaling. The inhibition of NO and proinflammatory cytokine production by nitrooleic acid was independent from PPAR-γ, JNK, p38, and STAT1/3. Nitrooleic acid may represent a novel class of agent as a host modulator which has therapeutic benefit in periodontal disease, though more work is needed to confirm this.

Nitro-Oleic Acid-Mediated Nitroalkylation Modulates the Antioxidant Function of Cytosolic Peroxiredoxin Tsa1 during Heat Stress in Saccharomyces cerevisiae.

Heat stress is one of the abiotic stresses that leads to oxidative stress. To protect themselves, yeast cells activate the antioxidant response, in which cytosolic peroxiredoxin Tsa1 plays an important role in hydrogen peroxide removal. Concomitantly, the activation of the heat shock response (HSR) is also triggered. Nitro-fatty acids are signaling molecules generated by the interaction of reactive nitrogen species with unsaturated fatty acids. These molecules have been detected in animals and plants. They exert their signaling function mainly through a post-translational modification called nitroalkylation. In addition, these molecules are closely related to the induction of the HSR. In this work, the endogenous presence of nitro-oleic acid (NO2-OA) in Saccharomyces cerevisiae is identified for the first time by LC-MS/MS. Both hydrogen peroxide levels and Tsa1 activity increased after heat stress with no change in protein content. The nitroalkylation of recombinant Tsa1 with NO2-OA was also observed. It is important to point out that cysteine 47 (peroxidatic) and cysteine 171 (resolving) are the main residues responsible for protein activity. Moreover, the in vivo nitroalkylation of Tsa1 peroxidatic cysteine disappeared during heat stress as the hydrogen peroxide generated in this situation caused the rupture of the NO2-OA binding to the protein and, thus, restored Tsa1 activity. Finally, the amino acid targets susceptible to nitroalkylation and the modulatory effect of this PTM on the enzymatic activity of Tsa1 are also shown in vitro and in vivo. This mechanism of response was faster than that involving the induction of genes and the synthesis of new proteins and could be considered as a key element in the fine-tuning regulation of defence mechanisms against oxidative stress in yeast.

Systemic bile acids potentiate airway hyperresponsiveness and modulate Th17 cell function in obesity-associated asthma

Abstract Obesity-associated asthma is phenotypically characterized by low grade inflammation and resistance to standard therapies. Like many other asthma endotypes, the molecular mechanisms contributing to obesity-associated asthma are diverse and ambiguous. A panoply of metabolites that act as signaling mediators are altered by obesity and may also promote lung dysfunction and a pro-asthma phenotype. Recent metabolomics studies indicate that bile acid profiles are altered in individuals with asthma, thus these metabolites were investigated in a murine model of obesity-associated asthma and clinically. In obese mice with allergic airway disease (AAD), the levels of β-muricholic acid (βMCA) and tauro-β-muricholic (tβMCA) were significantly increased in serum and positively correlated with impaired lung function. Two conjugated bile acids, glycocholic acid (GCA) and glycoursodeoxycholic acid (GUDCA), were elevated in the plasma of high body mass index (BMI) individuals and correlated with both BMI and airway hyperreactivity as measured by FEV1, forced expiratory volume in one second. In vitro differentiated T helper (Th) cells were treated with tβMCA and βMCA, which resulted in changes in T cell metabolism that were specific to Th17 cells. In addition, tβMCA treatment increased IL-17 production from Th17 cells upon stimulation. Finally, the anti-inflammatory and metabolic regulatory activities of nitro-oleic acid (NO2-OA) were evaluated in the murine model of obesity-associated asthma. NO2-OA reduced levels of βMCA and tβMCA, with a concomitant reduction in tissue resistance and elastance, providing a potential approach to improving the current standard of care for obese individuals with asthma. Supported by R01HL146445 (MLM), S10OD023402 (SGW), R61HL157069 (SGW, BAF, FH), R01HL132550 (BAF)