Nitro-oleic acid reduces thoracic aortic aneurysm progression in a mouse model of Marfan syndrome

Abstract

Aims Marfan syndrome (MFS) is a connective tissue disorder caused by mutations in the Fibrillin-1 gene. It is associated with formation of thoracic aortic aneurysms that can potentially be a life-threatening condition due to aortic rupture or dissection. Excessive non-canonical transforming growth factor beta signalling, mediated by activation of extracellular-signal regulated kinases 1/2 (ERK1/2), as well as inducible nitric oxide synthase (NOS2)-dependent nitric oxide production have been identified to drive aortic pathology in MFS through induction of elastin fragmentation and smooth muscle cell apoptosis. Despite promising results in animal studies, specific pharmacological interventions approved for clinical use in patients with MFS-related aortic disease are rare. Nitro-oleic acid (NO2-OA) is an endogenously generated signalling modulator, which is available as an oral compound and has been shown to inhibit ERK1/2 activation and NOS2 expression in different disease models, thereby exerting promising therapeutic effects. In this study, we investigated whether NO2-OA decreases aortic dilation in MFS. Methods and Results Eight-week-old MFS (Fbn1C1041G/+) mice were treated with NO2-OA or vehicle for four weeks via subcutaneously implanted osmotic minipumps. Echocardiography indicated progressive ascending aortic dilation and wall stiffening in MFS mice, which was significantly attenuated by NO2-OA treatment. This protective effect was mediated by inhibition of aortic ERK1/2, Smad2 as well as nuclear factor kappa B overactivation and consequent attenuation of elastin fragmentation by matrix metalloproteinase 2, apoptosis and collagen deposition. Critically, the therapeutic efficacy of NO2-OA in MFS was further emphasized by demonstrating its capability to reduce lethal aortic complications in Fbn1C1041G/+mice challenged with Angiotensin II. Conclusion NO2-OA distinctly attenuates progression of aortic dilation in MFS via modulation of well-established disease-mediating pathways, thereby meriting further investigation into its application as a therapeutic agent for the treatment of this condition. Translational perspective Thoracic aortic aneurysm formation is the major life-threatening complication of Marfan syndrome, a relatively common genetic connective tissue disorder. Although various potential therapeutic targets have been identified, specific pharmacological treatment options are still unavailable. In this study, we demonstrate that Nitro-oleic acid reduces ascending aortic elastin fragmentation, apoptosis, and fibrotic remodelling in Marfan syndrome through inhibition of extracellular-signal regulated kinases 1/2, Smad2 as well as nuclear factor kappa B overactivation and thereby mitigates aneurysm formation. Thus, Nitro-oleic acid, which has been developed as an oral compound, emerges as a potential treatment option for Marfan-related aortic disease.

Allopurinol Blocks Aortic Aneurysm in a Mouse Model of Marfan Syndrome via Reducing Aortic Oxidative Stress

“…The pathophysiological significance of these latter results in the MFS aortic media suggests several conclusions: (i) the accumulation of 3-NT is representative of abnormal RNS formation because of the pathological uncoupling of NO, which in turn leads to protein nitration via the formation of the highly reactive intermediate peroxynitrite and its subsequent product 3-NT 71 . This 3-NT upsurge in MFS aortic media is consistent with the recent demonstration of NO uncoupling in aneurysm formation in both MFS mice and patients 64,72,73 . Along this line of evidence, we previously identified actin as a significant nitrated protein target in MFS aorta from MFS patients 17 , contributing in this manner to the reported damaged contractile properties of VSMC in MFS 74 ; (ii) redox stress is so elevated in MFS aorta that the intrinsic physiological antioxidant response mediated by the nuclear translocation of pNRF2 54 is not high enough to compensate it.…”

“…Our results place redox stress among the molecular mechanisms that actively participate in the pathogenesis of aortic aneurysm in MFS by the consistent overproduction of ROS mediated by upregulation of XOR (current study), the NADPH oxidases NOX4 17 and NOX2 64 , the dysfunction of eNOS 72 , and mitochondria-associated redox stress 85 , all being studies performed both in MFS murine models and patients. How, and to what extent, do each of these interlinked mechanisms participate in the aortic injury is currently unknown, but most likely they all act additively or synergistically to damage the aorta severely and permanently.…”

“…It is possible that XOR upregulation only occurs while the aortic dilation undergoes rapid growth, which we found to occur until 3 months of age, becoming slower in older animals 45 . However, no differences between WT and MFS aortae have been reported regarding XOR activity in the study context of the aortic reactivity of MFS aorta 14 , and nitro-oleic acid as a mediator in ERK1/2 and NOS2 expression in MFS aortopathy 64 . Explanations for this apparent discrepancy may be related to the different murine MFS models used (mgR/mgR and AngII infusion-induced acceleration of the aortopathy in MFS mouse, respectively) or the different XOR activity assays utilized, and/or even to local animal facility conditions.…”

Nitro-Oleic Acid (NO2-OA) Improves Systolic Function in Dilated Cardiomyopathy by Attenuating Myocardial Fibrosis

“…Also, NO 2 -OA inhibits Stat3 phosphorylation via direct nitroalkylation in a human keratinocyte cell line [44]. Finally, only very recently, NO 2 -OA was shown to interfere with phosphorylation of Smad2/3, Stat3, and Erk1/2 in a murine model of Marfan's disease, further supporting the data presented herein [45].…”

Fatty acid nitroalkene reversal of established lung fibrosis

“…Of relevance to the present experimental design, the in vitro and in vivo administration of a synthetic homolog of endogenous 9- and 10-nitro-octadec-9( E )-enoic acid (nitro-oleic acid, NO 2 -OA) limits the evolution of fibrotic responses in multiple disease models. These include systemic and pulmonary hypertension [ [24] , [25] , [26] ], obesity-induced diabetes [ 27 ], colitis [ 28 ], atherosclerosis [ 29 ], nephropathy [ 30 ], hepatic steatosis [ 31 ], hypertension-induced atrial fibrillation, ischemia-induced myocardial arrhythmia [ 32 , 33 ] and Marfan's syndrome-related aortic rupture [ 34 ]. In these studies, tissue-protective effects were an aggregate result of nitroalkene-induced post-translational modification of functionally-significant cysteine residues in proteins that regulate pro-inflammatory and adaptive gene expression responses, immune cell activation, oxidative inflammatory mediator generation and the activity of multiple cell signaling pathways [ 22 , 23 , 35 , 36 ].…”