Paraoxonase 1 activity as a new biochemical marker in the diagnosis of peripheral arterial disease

Aim: Peripheral artery disease (PAD) is an atherosclerotic disease. It is seen in older ages. It causes cardiovascular morbidity and mortality. PAD may progress without any symptoms. Despite its high frequency, there is no laboratory parameter that directly indicates peripheral arterial disease in routine biochemical tests. The relationship between oxidative stress increase and PAD is known. In this study, it is aimed to show the possible usage of the activities of the antioxidant enzymes paraoxonase 1 and arylesterase as a new marker in the diagnosis of PAD. Material and Methods: A total of 70 individuals, including 35 in the control group and 35 peripheral artery patients, were included in this study. The collected blood serums were separated and stored at -80 °C. Paraoxonase 1 and arylesterase activities were measured using the spectrophotometric method in the serum which was dissolved at room temperature. The results were subjected to statistical analysis. P <0.05 was accepted as the level of significance. Results: In the peripheral arterial disease group, the paraoxonase 1 and arylesterase activities were found to be significantly lower than those in the control group (p <0.05). In peripheral arterial disease, paraoxonase 1 and arylesterase activities were shown to decrease. Conclusion: In peripheral arterial disease, paraoxonase 1 and arylesterase activities were found to decrease significantly. The results of similar studies related to atherosclerosis in the literature were in line with our findings. It would be beneficial to support the results of this study with new studies and evaluate paraoxonase 1 and arylesterase activities in routine biochemistry laboratories for the diagnosis and follow-up of peripheral arterial disease.


Introduction
Peripheral arterial disease (PAD) is an atherosclerotic disease.
It is seen in older ages. It causes cardiovascular morbidity and mortality. PAD may progress without any symptoms [1]. Although its frequency is high, there is no laboratory parameter that directly indicates peripheral arterial disease in routine biochemical tests. The paraoxonase (PON1) enzyme is an esterase enzyme whose antioxidant aspect is evident.
It is firmly attached to HDL. Thanks to the PON1 enzyme, it has been demonstrated in studies that HDL reduces lipid peroxides by various enzymatic mechanisms after accumulation of lipid peroxides forming as a result of oxidation of LDL [1]. Paraoxonase 1 activity is variable and affected by environmental factors. It differs based on communities.
Paraoxonase 1 and Arylesterase (ARY) are enzymes in the esterase group that are encoded by the same gene whose active centers are similar. The primary importance of ARY is that it is an indicator of the actual protein that is not affected by changes in PON1. Disruption of the balance between oxidative stress and antioxidant capacity and formation of oxidative damage cause many serious diseases [2][3][4][5][6][7][8]. The relationship between oxidative stress increase and PAD is known [9]. In this study, it is aimed to show the possible usage of the activities of the antioxidant enzymes paraoxonase 1 and arylesterase as a new marker in the diagnosis of PAD.

Measurement of Paraoxonase 1 (PON1) and Arylesterase (ARY) Activities
Paraoxonase 1 and arylesterase activities were measured by the spectrophotometric method in the serum using a commercial kit.

Paraoxonase 1 (PON1)
A fully automated and colorimetric commercial kit was used

Statistical Analysis
The results were subjected to statistical analysis. ANOVA was applied with the SPSS package program. There were two groups in total, and for this reason, post-hoc tests were not needed. In the statistical analysis, p<0.05 was accepted as the level of significance in the comparison between the groups.

Results
The mean age of the peripheral arterial disease group was 67.80 ± 8.70, whereas the mean age of the control group was 68.23 ± 7.80. In the peripheral arterial disease group, the paraoxonase 1 and arylesterase activities were significantly lower than those in the control group (p<0.05). The PON1 activity for the control (n = 35) and peripheral artery disease (n = 35) groups was found respectively as 509.54 ± 33.68 and 486.83 ± 30.93 (p = 0.004), while the ARY activity was respectively 612.17 ± 46.26 and 520.71 ± 52.63 (p<0.001). The results are shown in Table 1 and Graphic 1 and 2 below.

Discussion
Peripheral arterial disease is a pathology that develops in the background of atherosclerosis. Atherosclerosis is an inflammatory disease caused by the combination of oxidized lipid accumulation in the intima layers of the vessels and immune cells. The most important step that initiates atherosclerosis is the migration of LDL cholesterol to the intima layer after its endothelial injury, oxidation and subsequent migration of monocytes and the formation of foam cells.
The foam cells then become fat lines in the endothelial layer, and then, form atheromatous plaques [10][11][12][13][14][15]. An increase in oxidative stress increases foam cell formation and atherosclerosis. There is no parameter that is used in clinical biochemistry practice in the direct diagnosis of peripheral arterial disease. The activity of the paraoxonase 1 enzyme, which is an antioxidant enzyme and not only prevents LDL oxidation but also increases the activity of HDL, may be a biochemical marker in the diagnosis of peripheral arterial disease. According to the results of our study, paraoxonase 1 and arylesterase activities were decreased significantly in peripheral arterial disease (p<0.05). In a clinical study, it was previously shown that a decrease in PON1 activity increases carotid atherosclerosis and LDL oxidation [13]. In a study on experimental animal models, it was shown that increased PON1 activity decreased atherosclerosis [14]. The results of these studies on atherosclerosis in the literature were in line with our findings. While it would be beneficial to support this study with new studies, evaluation of the activities of the paraoxonase 1 and arylesterase enzymes in routine biochemistry laboratories may provide evidence for the diagnosis and follow-up of peripheral artery disease.

Conclusion
While deciding about the diagnosis and treatment of a patient, meticulous, clear, and accurate use of the information proven by scientific data is expressed as evidence-based medicine [15]. Therefore, a decrease in the activity of the paraoxonase 1 enzyme in peripheral arterial disease may be an important clinical biochemistry indicator in terms of evidence-based medicine.