Electrophilic Fatty Acid Species Inhibit 5-Lipoxygenase and Attenuate Sepsis-Induced Pulmonary Inflammation

Abstract

Aims: The reaction of nitric oxide and nitrite-derived species with polyunsaturated fatty acids yields electrophilic fatty acid nitroalkene derivatives (NO 2 -FA), which display anti-inflammatory properties. Given that the 5-lipoxygenase (5-LO, ALOX5) possesses critical nucleophilic amino acids, which are potentially sensitive to electrophilic modifications, we determined the consequences of NO 2 -FA on 5-LO activity in vitro and on 5-LOmediated inflammation in vivo. Results: Stimulation of human polymorphonuclear leukocytes (PMNL) with nitro-oleic (NO 2 -OA) or nitro-linoleic acid (NO 2 -LA) (but not the parent lipids) resulted in the concentrationdependent and irreversible inhibition of 5-LO activity. Similar effects were observed in cell lysates and using the recombinant human protein, indicating a direct reaction with 5-LO. NO 2 -FAs did not affect the activity of the platelet-type 12-LO (ALOX12) or 15-LO-1 (ALOX15) in intact cells or the recombinant protein. The NO 2 -FAinduced inhibition of 5-LO was attributed to the alkylation of Cys418, and the exchange of Cys418 to serine rendered 5-LO insensitive to NO 2 -FA. In vivo, the systemic administration of NO 2 -OA to mice decreased neutrophil and monocyte mobilization in response to lipopolysaccharide (LPS), attenuated the formation of the 5-LO product 5-hydroxyeicosatetraenoic acid (5-HETE), and inhibited lung injury. The administration of NO 2 -OA to 5-LO knockout mice had no effect on LPS-induced neutrophil or monocyte mobilization as well as on lung injury. Innovation: Prophylactic administration of NO 2 -OA to septic mice inhibits inflammation and promotes its resolution by interfering in 5-LO-mediated inflammatory processes. Conclusion: NO 2 -FAs directly and irreversibly inhibit 5-LO and attenuate downstream acute inflammatory responses. Antioxid. Redox Signal. 20, 2667Signal. 20, -2680

Nitro-fatty acids in cardiovascular regulation and diseases characteristics and molecular mechanisms

“…Selective adduction of Cys418 in 5-LO was identified. Specificity of the reaction was further confirmed using 5-LO knockout mice in which administration of NO 2 -FAs had no effect on LPS-induced neutrophil or monocyte mobilization in the lungs (80). Similarly, NO 2 -FAs administration promotes neutrophil apoptosis and subsequent phagocytosis by alveolar macrophages limiting allergic hyperesponsiveness of the lung (81).…”

“…To test the role of NO 2 -FAs in experimental models of inflammatory responses of the lungs, the effects of nitro-FA on LPS-induced lipoxygenase activation were studied in the mouse lung (80). Systemic delivery of NO 2 -FAs reduced the development of lung injury concomitant with a reduction of circulating and pulmonary levels of the 5-lipoxygenase (5-LO) products, LTB4 and 5-HETE and 12-HETE.…”

“…NO 2 -FAs inhibits the formation of pro-inflammatory lipid mediators (e.g. PGE 2 , LTB4, 5- 12-HETE) and promotes anti-inflammatory eicosanoids (EETs) by inhibiting the activity of 5-lipoxygenase (80) and soluble epoxide hydrolase (75), respectively. At the cellular membrane, NO 2 -FAs interfere with angiotensin II receptor (9), TGFβ receptor (87) or Toll-like receptor 4 (31) by preventing G-protein coupled receptor second messenger signaling, receptor dimerization or membrane recruitment, respectively.…”

Role of bioactive lipid mediators in obese adipose tissue inflammation and endocrine dysfunction

“…NO2eFAs can regulate glucose and lipid metabolism by binding to PPARg (Li et al, 2008;Schopfer et al, 2005). Recently, NO 2 eFAs were reported to inactivate the 5-LOX enzyme, resulting in a lower production of inflammatory eicosanoids (Awwad et al, 2014). More recently, Kelley et al have reported that NO 2 eFAs improve glucose tolerance and reduce the expression of inflammatory cytokines and circulating leptin levels while increasing adiponectin in a HFD model of obesity (Kelley et al, 2014).…”

Evaluation of 10-Nitro Oleic Acid Bio-Elimination in Rats and Humans

“…activation of Nrf2- and heat shock responses, TLR4/NF-κB inhibition) led to its evaluation in animal models of disease and more recently to its pre-clinical development for use in humans17181920. Oral, subcutaneous or intravenous administration of NO 2 -OA is protective in animal models of inflammatory bowel disease, heart and kidney ischemia reperfusion, adriamycin-induced renal toxicity, restenosis after endoluminal injury, lung injury, atherosclerosis development, endotoxemia and diabetes among others10212223242526272829. An initial characterization of NO 2 -OA metabolism in mice revealed the presence of secondary nitrated species that included β-oxidation products, non-electrophilic nitroalkene reduction derivatives, glutathione conjugates and coenzyme A esters30.…”