ABC | Volume 113, Nº6, December 2019

Original Article Barbosa et al Nrf2, NF- κ B and PPAR β / δ in CAD patients Arq Bras Cardiol. 2019; 113(6):1121-1127 Table 2 – mRNA expression levels in the group without CAD and the CAD Group Parameters Group without CAD CAD Group p value Nrf2 1.16 ± 0.76 1.35 ± 0.57 0.35 NF-B 0.95 ± 0.33 1.08 ± 0.50 0.58 NQO1 0.81 ± 0.55 1.05 ± 0.88 0.37 PPARβ/δ 0.56 ± 0.34 1.17 ± 0.86 0.008 Nrf2, NF-kB, NOQ1 and PPAR β/δ mRNA expression was performed in PBMC by real-time quantitative PCR. Data were expressed as mean ± SD. CAD: coronary artery disease. (ICAM-1). 30 NF- κ B inhibition in endothelial cells resulted in reduced development of atherosclerosis and was correlated with reduced expression of pro-inflammatory cytokines, chemokines and adhesion molecules in the aortas of mice fed with cholesterol-rich diet. 31 Some studies demonstrate that, as a protection mechanism, in an early stage of diseases, Nrf2 has its activity increased in order to avoid damage induced by ROS. In the final stage, due to the chronicity and/or severity of the disease, this protection mechanism may become saturated by the excess of EROs leading to the reduction of Nrf2 32,33 or the Nrf2 appears to be insufficiently capable of antagonizing NF- κ B and it remains high. 26 Despite this, the effects of CAD on the Nrf2-Keap1 system are not well established. However, patients with CAD had lower gene expression of Nrf2/ARE and glutathione (GSH). 27 An important phase of atherosclerotic plaque formation is endothelial infiltration well established by macrophages and formation of foam cells. In rats, Nrf2 is an important component in this process, as macrophages exposed to oxidized LDL promoted increased expression of Nrf2, which indirectly protected macrophages from oxi-LDL mediated lesions through phase II antioxidant enzymes. 34 In addition, the absence of Nrf2 in macrophages from mice consuming a high-fat diet increased the formation of foam cells and the progression of atherosclerosis, suggesting that Nrf2 is important in resistance to atherosclerosis. 35 Increased expression of Nrf2 at this stage of development of atherosclerosis is important because the effects on heme oxygenase-1 (HO-1) expression, which produces antiatherogenic effects as a reduction in the formation of foam cells 36 and NQO1 also proved to be important in the protection against atherosclerosis. 37 In the present study, there were no differences in the Nrf2 or NF- κ B mRNA expression between patients in the CAD group and the group without CAD possibly due to the fact that the patients in the two groups were elderly, hypertensive and/or diabetic, demonstrating that both groups did not include healthy patients. In addition, all the patients used several medications with potential antioxidant effect. 38,39 With age, expression of several Nrf2 downstream targets declined. 40 It is still important to emphasize that both hypertension and diabetes are related to increased oxidative stress, accumulation of reactive oxygen species and inflammation. 9,41 In the present study, the PPAR β / δ was high compared to the patients without CAD. It seems to be protective since it has been shown that the adequate balance of PPAR β / δ activation in the different cardiac cell types may be important for potential cardioprotective effects of PPAR β / δ . 42 An  in vivo study showed that cardiac specific overexpression of PPAR β / δ led to increased myocardial glucose utilization and did not alter cardiac function but exerted a protective effect on ischemia/reperfusion‑induced myocardial injury. 43 In addition, cardiac PPAR β / δ deletion in mice resulted in cardiac dysfunction, hypertrophy and congestive heart failure. 17 Additionally, PPAR β / δ has been described in several biological functions, including cell survival. 44,45 Studies show that inflammation, ROS and oxidized LDLs induce endothelial cell apoptosis, representing the beginning of the development of atherosclerotic lesions. 45 Thus, assays performed on keratinocytes have shown that increased production of proinflammatory cytokines is capable of elevating PPAR β / δ expression, which in turn regulates the expression of apoptosis-related genes, resulting in increased resistance to cell death. 44 Given the importance of PPAR β / δ and the transcription factors NF- κ B and Nrf2 effects for the CAD patients – the Nrf2 orchestrating the production of antioxidant and phase 2 detoxifying enzymes being considered a protective factor against both oxidative stress and inflammation, 46 PPAR β / δ promoting cardioprotection 42 and NF- κ B regulating inflammation 12 – a better understanding of how they are expressed in CAD patients is useful so that strategies can be used in an attempt to modulate these transcription factors. Some studies proposed that nutrients containing plant-based Nrf2 inducers may help to improve the Nrf2-Keap1 system. 25,47 This study presented a range of limitations that warrant consideration. Firstly, this study should have a healthy control group for comparison. Secondly, it would be interesting to stratify the results by risk factor and scintigraphy results, but the sample was not large enough for this. Thirdly, unfortunately, we did not perform another Nrf2 , NF- κ B and PPAR β / δ target genes that encode antioxidant enzymes and proinflammatory cytokines to confirm the Nrf2, NF- κ B and PPAR β / δ expression network. Furthermore, it was not possible to calculate non‑HDL cholesterol. Further studies should be encouraged to explore this issue. Considering these limitations, this was a very well-controlled protocol, which allowed us to conclude that the results are considerably relevant. Conclusion The present study revealed increased expression of PPAR β / δ in the PBMC of CAD patients while no differences were observed in Nrf2 or NF- κ B mRNA expressions. These findings may lead to possible therapies, targets and future research for treatment in these patients. 1124