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Soluble guanylate cyclase (sGC) catalyzes the conversion of guanosine triphosphate into cyclic guanosine-3',5'-monophosphate, a key second messenger in cell signaling and tissue homeostasis. It was recently demonstrated that sGC stimulation is associated with a marked antiinflammatory effect in the liver of mice with experimental nonalcoholic steatohepatitis (NASH). Here, we investigated the mechanisms underlying the antiinflammatory effect of the sGC stimulator praliciguat (PRL) in the liver. Therapeutic administration of PRL exerted antiinflammatory and antifibrotic actions in mice with choline-deficient L-amino acid-defined high-fat diet-induced NASH. The PRL antiinflammatory effect was associated with lower F4/80- and CX3CR1-positive macrophage infiltration into the liver in parallel with lower Ly6CHigh- and higher Ly6CLow-expressing monocytes in peripheral circulation. The PRL antiinflammatory effect was also associated with suppression of hepatic levels of interleukin (IL)-1β, NLPR3 (NACHT, LRR, and PYD domain-containing protein 3), ASC (apoptosis-associated specklike protein containing a caspase-recruitment domain), and active cleaved-caspase-1, which are components of the NLRP3 inflammasome. In Kupffer cells challenged with the classical inflammasome model of lipopolysaccharide plus adenosine triphosphate, PRL inhibited the priming (expression of Il1b and Nlrp3) and blocked the release of mature IL-1β. Mechanistically, PRL induced the protein kinase G (PKG)-mediated phosphorylation of the VASP (vasodilator-stimulated phosphoprotein) Ser239 residue which, in turn, reduced nuclear factor-κB (NF-κB) activity and Il1b and Nlrp3 gene transcription. PRL also reduced active cleaved-caspase-1 levels independent of pannexin-1 activity. These data indicate that sGC stimulation with PRL exerts antiinflammatory actions in the liver through mechanisms related to a PKG/VASP/NF-κB/NLRP3 inflammasome circuit. [ABSTRACT FROM AUTHOR]

Soluble epoxide hydrolase (sEH) is an emerging therapeutic target in a number of diseases that have inflammation as a common underlying cause. sEH limits tissue levels of cytochrome P450 (CYP) epoxides derived from omega-6 and omega-3 polyunsaturated fatty acids (PUFA) by converting these antiinflammatory mediators into their less active diols. Here, we explored the metabolic effects of a sEH inhibitor (t-TUCB) in fat-1 mice with transgenic expression of an omega-3 desaturase capable of enriching tissues with endogenous omega-3 PUFA. These mice exhibited increased CYP1A1, CYP2E1, and CYP2U1 expression and abundant levels of the omega-3-derived epoxides 17,18-epoxyeicosatetraenoic acid (17,18-EEQ) and 19,20-epoxydocosapentaenoic (19,20-EDP) in insulinsensitive tissues, especially liver, as determined by LC-ESI-MS/MS. In obese fat-1 mice, t-TUCB raised hepatic 17,18-EEQ and 19,20-EDP levels and reinforced the omega-3-dependent reduction observed in tissue inflammation and lipid peroxidation. t-TUCB also produced a more intense antisteatotic action in obese fat-1 mice, as revealed by magnetic resonance spectroscopy. Notably, t-TUCB skewed macrophage polarization toward an antiinflammatory M2 phenotype and expanded the interscapular brown adipose tissue volume. Moreover, t-TUCB restored hepatic levels of Atg12- Atg5 and LC3-II conjugates and reduced p62 expression, indicating up-regulation of hepatic autophagy. t-TUCB consistently reduced endoplasmic reticulum stress demonstrated by the attenuation of IRE-1α and eIF2α phosphorylation. These actions were recapitulated in vitro in palmitate-primed hepatocytes and adipocytes incubated with 19,20-EDP or 17,18-EEQ. Relatively similar but less pronounced actions were observed with the omega-6 epoxide, 14,15-EET, and nonoxidized DHA. Together, these findings identify omega-3 epoxides as important regulators of inflammation and autophagy in insulin-sensitive tissues and postulate sEH as a druggable target in metabolic diseases. [ABSTRACT FROM AUTHOR]