Electrophilic nitro-fatty acids suppress psoriasiform dermatitis: STAT3 inhibition as a contributory mechanism.
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ABSTRACT:
SUBMITTER: Wang P
PROVIDER: S-EPMC8111320 | biostudies-literature |
REPOSITORIES: biostudies-literature
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Project description:BackgroundReactions between nitric oxide (NO), nitrite (NO2-), and unsaturated fatty acids give rise to electrophilic nitro-fatty acids (NO2 -FAs), such as nitro oleic acid (OA-NO2 ) and nitro linoleic acid (LNO2 ). Endogenous electrophilic fatty acids (EFAs) mediate anti-inflammatory responses by modulating metabolic and inflammatory signal transduction reactions. Hence, there is considerable interest in employing NO2 -FAs and other EFAs for the prevention and treatment of inflammatory disorders. Thus, we sought to determine whether OA-NO2 , an exemplary nitro-fatty acid, has the capacity to inhibit cutaneous inflammation.MethodsWe evaluated the effect of OA-NO2 on allergic contact dermatitis (ACD) using an established model of contact hypersensitivity in C57Bl/6 mice utilizing 2,4-dinitrofluorobenzene as the hapten.ResultsWe found that subcutaneous (SC) OA-NO2 injections administered 18 h prior to sensitization and elicitation suppresses ACD in both preventative and therapeutic models. In vivo SC OA-NO2 significantly inhibits pathways that lead to inflammatory cell infiltration and the production of inflammatory cytokines in the skin. Moreover, OA-NO2 is capable of enhancing regulatory T-cell activity. Thus, OA-NO2 treatment results in anti-inflammatory effects capable of inhibiting ACD by inducing immunosuppressive responses.ConclusionOverall, these results support the development of OA-NO2 as a promising therapeutic for ACD and provides new insights into the role of electrophilic fatty acids in the control of cutaneous immune responses potentially relevant to a broad range of allergic and inflammatory skin diseases.
| S-EPMC5352476 | biostudies-literature
Project description:Endogenous electrophilic fatty acids mediate anti-inflammatory responses by modulating metabolic and inflammatory signal transduction and gene expression. Nitro-fatty acids and other electrophilic fatty acids may thus be useful for the prevention and treatment of immune-mediated diseases, including inflammatory skin disorders. In this regard, subcutaneous (SC) injections of nitro oleic acid (OA-NO2), an exemplary nitro-fatty acid, inhibit skin inflammation in a model of allergic contact dermatitis (ACD). Given the nitration of unsaturated fatty acids during metabolic and inflammatory processes and the growing use of fatty acids in topical formulations, we sought to further study the effect of nitro-fatty acids on cutaneous inflammation. To accomplish this, the effect of topically applied OA-NO2 on skin inflammation was evaluated using established murine models of contact hypersensitivity (CHS). In contrast to the effects of subcutaneously injected OA-NO2, topical OA-NO2 potentiated hapten-dependent inflammation inducing a sustained neutrophil-dependent inflammatory response characterized by psoriasiform histological features, increased angiogenesis, and an inflammatory infiltrate that included neutrophils, inflammatory monocytes, and γδ T cells. Consistent with these results, HPLC-MS/MS analysis of skin from psoriasis patients displayed a 56% increase in nitro-conjugated linoleic acid (CLA-NO2) levels in lesional skin compared to non-lesional skin. These results suggest that nitro-fatty acids in the skin microenvironment are products of cutaneous inflammatory responses and, in high local concentrations, may exacerbate inflammatory skin diseases.
| S-EPMC5767521 | biostudies-literature
Project description:Nitro-fatty acids (NFAs) are endogenously formed lipid mediators that cause a broad spectrum of anti-inflammatory effects by covalent modification of key proteins within inflammatory signaling pathways. Their potential as therapeutics has been demonstrated in numerous animal models of disease. Herein, we evaluated the anti-tumorigenic effects of NFAs in the colon carcinoma cell line Caco-2 and other solid and leukemic tumor cell lines. NFAs inhibited the ubiquitin–proteasome system (UPS), leading to polyubiquitination and inhibition of the proteasome activities. Suppression of the UPS induced the pro-apoptotic transcription factor CHOP by activation of the unfolded protein response (UPR), resulting in tumor cell death. NFA-mediated effects on UPS and UPR were rather strong, highly specific, largely irreversible, and represent a mechanistically new mode of action for pharmacological suppression of the UPS. Taking into account their favorable safety profile in clinical phase I trials in combination with their well-recognized anti-tumorigenic efficacy covering solid tumors, we conclude that NFAs are innovative proteasome inhibitor drug candidates that may have a large potential to overcome the limitations of the classical proteasome inhibitors.
2024-03-26 | PXD023372 | Pride
Project description:Nitro-fatty acids are electrophilic anti-inflammatory mediators which are generated during myocardial ischemic injury. Whether these species exert anti-arrhythmic effects in the acute phase of myocardial ischemia has not been investigated so far. Herein, we demonstrate that pretreatment of mice with 9- and 10-nitro-octadec-9-enoic acid (nitro-oleic acid, NO2-OA) significantly reduced the susceptibility to develop acute ventricular tachycardia (VT). Accordingly, epicardial mapping revealed a markedly enhanced homogeneity in ventricular conduction. NO2-OA treatment of isolated cardiomyocytes lowered the number of spontaneous contractions upon adrenergic isoproterenol stimulation and nearly abolished ryanodine receptor type 2 (RyR2)-dependent sarcoplasmic Ca2+ leak. NO2-OA also significantly reduced RyR2-phosphorylation by inhibition of increased CaMKII activity. Thus, NO2-OA might be a novel pharmacological option for the prevention of VT development.
| S-EPMC7501300 | biostudies-literature
Project description:AimsElectrophilic fatty acid nitroalkene derivatives, products of unsaturated fatty acid nitration, exert long-term cardiovascular protection in experimental models of metabolic and cardiovascular diseases. The goal of this study is to examine the effects of nitro-fatty acids in the regulation of upstream signalling events in nuclear factor-?B (NF-?B) activation and determine whether low-dose acute administration of nitro-fatty acids reduces vascular inflammation in vivo.Methods and resultsUsing NF-?B-luciferase transgenic mice, it was determined that pre-emptive treatment with nitro-oleic acid (OA-NO2), but not oleic acid (OA) inhibits lipopolysaccharide (LPS)-induced NF-?B activation both in vivo and in isolated macrophages. Acute intravenous administration of OA-NO2 was equally effective to inhibit leukocyte recruitment to the vascular endothelium assessed by intravital microscopy and significantly reduces aortic expression of adhesion molecules. An acute treatment with OA-NO2 in vivo yielding nanomolar concentrations in plasma, is sufficient to inhibit LPS-induced Toll-like receptor 4 (TLR4)-induced cell surface expression in leukocytes and NF-?B activation. In vitro experiments reveal that OA-NO2 suppresses LPS-induced TLR4 signalling, inhibitor of ?B (I?B?) phosphorylation and ubiquitination, phosphorylation of the I?B kinase (IKK), impairing the recruitment of the TLR4 and TNF receptor associated factor 6 (TRAF6) to the lipid rafts compartments.ConclusionThese studies demonstrate that acute administration of nitro-fatty acids is effective to reduce vascular inflammation in vivo. These findings reveal a direct role of nitro-fatty acids in the disruption of the TLR4 signalling complex in lipid rafts, upstream events of the NF-?B pathway, leading to resolution of pro-inflammatory activation of NF-?B in the vasculature.
| S-EPMC3598418 | biostudies-literature
Project description:Nitro-fatty acids (NO(2)-FA) are electrophilic signaling mediators formed by reactions of nitric oxide and nitrite. NO(2)-FA exert anti-inflammatory signaling actions through post-translational protein modifications. We report that nitro-oleic acid (OA-NO(2)) stimulates proMMP-7 and proMMP-9 proteolytic activity via adduction of the conserved cysteine switch domain thiolate. Biotin-labeled OA-NO(2) showed this adduction occurs preferentially with latent forms of MMP, confirming a role for thiol alkylation by OA-NO(2) in MMP activation. In addition to regulating pro-MMP activation, MMP expression was modulated by OA-NO(2) via activation of peroxisome proliferator-activated receptor-?. MMP-9 transcription was decreased in phorbol 12-myristate 13-acetate-stimulated THP-1 macrophages to an extent similar to that induced by the peroxisome proliferator-activated receptor-? agonist Rosiglitazone. This was affirmed using a murine model of atherosclerosis, ApoE(-/-) mice, where in vivo OA-NO(2) administration suppressed MMP expression in atherosclerotic lesions. These findings reveal that electrophilic fatty acid derivatives can serve as effectors during inflammation, first by activating pro-MMP proteolytic activity via alkylation of the cysteine switch domain, and then by transcriptionally inhibiting MMP expression, thereby limiting the further progression of inflammatory processes.
| S-EPMC3091216 | biostudies-literature
Project description:Lack of non-invasive diagnostic tools and effective therapies constitute two of the major hurdles for a bona fide treatment against non-alcoholic steatohepatitis (NASH) progression and/or regression of nonalcoholic fatty liver disease (NAFLD). Nitro-oleic acid (OA-NO2) has been proven effective in multiple experimental models of inflammation and fibrosis. Thus, the potential benefit of in vivo administration of OA-NO2 to treat advanced NAFLD was studied in a model of long-term NASH diet-induced liver damage. Non-invasive imaging (e.g. photoacustic-ultrasound (PA-US)) was pursued to establish advanced experimental NASH in mice in which both steatosis and fibrosis were diagnosed prior experimental OA-NO2 therapy. CLAMS and NMR-based analysis demonstrates that OA-NO2 improves body composition and energy metabolism and inhibits hepatic triglyceride accumulation. PA-US imaging revealed a robust inhibition of liver steatosis and fibrosis by OA-NO2. RNA-sequencing analysis uncovered inflammation and fibrosis as major pathways suppressed by OA-NO2 administration, as well as regulation of lipogenesis and lipolysis pathways, with a robust inhibition of SREBP1-dependent lipogenic gene expression by OA-NO2. Global liver transcriptome in response to OA-NO2 was confirmed in vivo and in isolated hepatocytes. These results were further supported by histological analysis and quantification of lipid accumulation, lobular inflammation (F4/80 staining) and fibrosis (collagen deposition, αSMA staining) as well as established parameters of liver damage (ALT). In vitro studies indicate that OA-NO2 inhibits TG biosynthesis and accumulation in hepatocytes and inhibits fibrogenesis in human stellate cells. Taken together, OA-NO2 improve steatohepatitis and fibrosis and may constitute an effective therapeutic approach against advanced NAFLD that warrants further clinical evaluation.
2019-02-08 | GSE126204 | GEO
Project description:Nitro-fatty acids are electrophilic signaling mediators formed in increased amounts during inflammation by nitric oxide and nitrite-dependent redox reactions. A more rigorous characterization of endogenously-generated species requires additional understanding of their gas-phase induced fragmentation. Thus, collision induced dissociation (CID) of nitroalkane and nitroalkene groups in fatty acids were studied in the negative ion mode to provide mass spectrometric tools for their structural characterization. Fragmentation of nitroalkanes occurred mainly through loss of the NO(2)(-) anion or neutral loss of HNO(2). The CID of nitroalkenes proceeds via a more complex cyclization, followed by fragmentation to nitrile and aldehyde products. Gas-phase fragmentation of nitroalkene functional groups with additional ? or ? unsaturation occurred through a multiple step cyclization reaction process, leading to 5 and 6 member ring heterocyclic products and carbon chain fragmentation. Cyclization products were not obtained during nitroalkane fragmentation, highlighting the role of double bond ? electrons during NO(2)(-) rearrangements, stabilization and heterocycle formation. The proposed structures, mechanisms and products of fragmentation are supported by analysis of (13)C and (15)N labeled parent molecules, 6 different nitroalkene positional isomers, 6 nitroalkane positional isomers, accurate mass determinations at high resolution and quantum mechanics calculations. Multiple key diagnostic ion fragments were obtained through this analysis, allowing for the precise placement of double bonds and sites of fatty acid nitration, thus supporting an ability to predict nitro positions in biological samples.
| S-EPMC3286133 | biostudies-literature
Project description:The addition of nitrogen dioxide (NO2) to the double bond of unsaturated fatty acids yields an array of electrophilic nitro-fatty acids (NO2-FA) with unique biochemical and signaling properties. During the last decade, NO2-FA have been shown to exert a protective role in various inflammatory and metabolic disorders. NO2-FA exert their biological effects primarily by regulating two central physiological adaptive responses: the canonical inflammatory signaling and metabolic pathways. In this mini-review, we summarize current knowledge on the regulatory role of NO2-FA in the inflammatory and metabolic response via regulation of nuclear factor kappa B (NF-?B) and peroxisome proliferator-activated receptor ? (PPAR?), master regulators of inflammation and metabolism. Moreover, the engagement of novel signaling and metabolic pathways influenced by NO2-FA, beyond NF-?B and PPAR signaling, is discussed herein.
| S-EPMC6151155 | biostudies-literature
Project description:Sirtuin 6, SIRT6, is critical for both glucose and lipid homeostasis and is involved in maintaining genomic stability under conditions of oxidative DNA damage such as those observed in age-related diseases. There is an intense search for modulators of SIRT6 activity, however, not many specific activators have been reported. Long acyl-chain fatty acids have been shown to increase the weak in vitro deacetylase activity of SIRT6 but this effect is modest at best. Herein we report that electrophilic nitro-fatty acids (nitro-oleic acid and nitro-conjugated linoleic acid) potently activate SIRT6. Binding of the nitro-fatty acid to the hydrophobic crevice of the SIRT6 active site exerted a moderate activation (2-fold at 20 μm), similar to that previously reported for non-nitrated fatty acids. However, covalent Michael adduct formation with Cys-18, a residue present at the N terminus of SIRT6 but absent from other isoforms, induced a conformational change that resulted in a much stronger activation (40-fold at 20 μm). Molecular modeling of the resulting Michael adduct suggested stabilization of the co-substrate and acyl-binding loops as a possible additional mechanism of SIRT6 activation by the nitro-fatty acid. Importantly, treatment of cells with nitro-oleic acid promoted H3K9 deacetylation, whereas oleic acid had no effect. Altogether, our results show that nitrated fatty acids can be considered a valuable tool for specific SIRT6 activation, and that SIRT6 should be considered as a molecular target for in vivo actions of these anti-inflammatory nitro-lipids.
| S-EPMC7939442 | biostudies-literature