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In situ generation, metabolism and immunomodulatory signaling actions of nitro-conjugated linoleic acid in a murine model of inflammation.

ABSTRACT: Conjugated linoleic acid (CLA) is a prime substrate for intra-gastric nitration giving rise to the formation of nitro-conjugated linoleic acid (NO₂-CLA). Herein, NO₂-CLA generation is demonstrated within the context of acute inflammatory responses both in vitro and in vivo. Macrophage activation resulted in dose- and time-dependent CLA nitration and also in the production of secondary electrophilic and non-electrophilic derivatives. Both exogenous NO₂-CLA as well as that generated in situ, attenuated NF-?B-dependent gene expression, decreased pro-inflammatory cytokine production and up-regulated Nrf2-regulated proteins. Importantly, both CLA nitration and the corresponding downstream anti-inflammatory actions of NO₂-CLA were recapitulated in a mouse peritonitis model where NO₂-CLA administration decreased pro-inflammatory cytokines and inhibited leukocyte recruitment. Taken together, our results demonstrate that the formation of NO₂-CLA has the potential to function as an adaptive response capable of not only modulating inflammation amplitude but also protecting neighboring tissues via the expression of Nrf2-dependent genes.

SUBMITTER: Villacorta L

PROVIDER: S-EPMC5881417 | biostudies-literature | 2018 May

REPOSITORIES: biostudies-literature

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In situ generation, metabolism and immunomodulatory signaling actions of nitro-conjugated linoleic acid in a murine model of inflammation.

Villacorta Luis L Minarrieta Lucia L Salvatore Sonia R SR Khoo Nicholas K NK Rom Oren O Gao Zhen Z Berman Rebecca C RC Jobbagy Soma S Li Lihua L Woodcock Steven R SR Chen Y Eugene YE Freeman Bruce A BA Ferreira Ana M AM Schopfer Francisco J FJ Vitturi Dario A DA

Redox biology 20180112

Conjugated linoleic acid (CLA) is a prime substrate for intra-gastric nitration giving rise to the formation of nitro-conjugated linoleic acid (NO2-CLA). Herein, NO2-CLA generation is demonstrated within the context of acute inflammatory responses both in vitro and in vivo. Macrophage activation resulted in dose- and time-dependent CLA nitration and also in the production of secondary electrophilic and non-electrophilic derivatives. Both exogenous NO2-CLA as well ...[more]

PMID: 29413964

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Project description:Nitroalkene fatty acids are formed in vivo and exert protective and anti-inflammatory effects via reversible Michael addition to thiol-containing proteins in key signaling pathways. Nitro-conjugated linoleic acid (NO2-CLA) is preferentially formed, constitutes the most abundant nitrated fatty acid in humans, and contains two carbons that could potentially react with thiols, modulating signaling actions and levels. In this work, we examined the reactions of NO2-CLA with low molecular weight thiols (glutathione, cysteine, homocysteine, cysteinylglycine, and ?-mercaptoethanol) and human serum albumin. Reactions followed reversible biphasic kinetics, consistent with the presence of two electrophilic centers in NO2-CLA located on the ?- and ?-carbons with respect to the nitro group. The differential reactivity was confirmed by computational modeling of the electronic structure. The rates (kon and koff) and equilibrium constants for both reactions were determined for different thiols. LC-UV-Visible and LC-MS analyses showed that the fast reaction corresponds to ?-adduct formation (the kinetic product), while the slow reaction corresponds to the formation of the ?-adduct (the thermodynamic product). The pH dependence of the rate constants, the correlation between intrinsic reactivity and thiol pKa, and the absence of deuterium solvent kinetic isotope effects suggested stepwise mechanisms with thiolate attack on NO2-CLA as rate-controlling step. Computational modeling supported the mechanism and revealed additional features of the transition states, anionic intermediates, and final neutral products. Importantly, the detection of cysteine-?-adducts in human urine provided evidence for the biological relevance of this reaction. Finally, human serum albumin was found to bind NO2-CLA both non-covalently and to form covalent adducts at Cys-34, suggesting potential modes for systemic distribution. These results provide new insights into the chemical basis of NO2-CLA signaling actions.

Dataset Information

In situ generation, metabolism and immunomodulatory signaling actions of nitro-conjugated linoleic acid in a murine model of inflammation.

Publications

In situ generation, metabolism and immunomodulatory signaling actions of nitro-conjugated linoleic acid in a murine model of inflammation.

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