Comparison of 8-hydroxy-2-deoxyguanosine, nadph oxidase 2 (NOX2) and nadph oxidase 4 (NOX4), total thiol and native thiol levels in obese patients with and without bariatric surgery

Objective: Obesity is a complex and multicomponent disorder caused by excess fat accumulation in the body secondary to increased energy intake. It causes comorbid conditions such as obesity, diabetes, cardiovascular diseases, high blood pressure, lipid metabolism disorders, stroke, some cancers, obstructive sleep apnea syndrome, non-alcoholic fatty liver disease, gastroesophageal reflux, polycystic ovary syndrome, infertility, osteoarthritis and psychiatric disorders, increases health expenditures. Obesity also increases the production of reactive oxygen species (ROS) and the development of oxidative stress. In this respect, it is essential to keep obesity under control or treat it. Reducing body weight should be aimed to reduce complications in obesity, protect health and extend life expectancy. In this study, 8 hydroxy-2-deoxyguanosine (8-OH dG/ 106 dG), NADPH oxidase 2 (NOX2) and NADPH oxidase 4 (NOX4), Total Thiol and Native Thiol levels were investigated in obese and non obese patients who underwent bariatric surgery. Thus, is oxidative DNA damage (8-OH dG/ 106 dG) reduced after bariatric surgery compared to obese patients? Is there a change in the level of endogenous oxidative damage (NOX2 and NOX4) after bariatric surgery? Is there a change in thiol homeostasis in obese patients after bariatric surgery? It is aimed to find answers to questions such as. Materials and Methods: The research was conducted on obese patients with and without bariatric surgery who came to Van Yüzüncü Yıl University Dursun Odabaş Medical Center, Endocrinology and Metabolic Diseases Polyclinic between 1.02.2023 and 1.07.2023. A total of 90 volunteers, 66 female and 24 male patients, were included in the study. In the study, 8-OH dG/ 106 dG, NOX2 and NOX4, Total Thiol and Native Thiol were detected in obese and non obese patients who had bariatric surgery between the ages of 18-65, levels were examined. The blood samples were centrifuged and stored at -40̊ C on the day they were taken. When the stored blood samples reached 45 patients and 45 controls, they were studied with the ELISA method in the biochemistry laboratory. End-point reading was made at 450 nm and the results were determined with the help of the standard curve. Results: Of the 90 patients included in the study, 66 (73.3%) were female and 24 (26.7%) were male. The Case group was patients who underwent bariatric surgery and their average Body Mass Index (BMI) was calculated as 31.5±7.2. The Control group was obese individuals who had not undergone surgery, and their average BMI was calculated as 38.2±3.73. BMI value in the case group was significantly lower than the control group (p:0.000). No significant difference was seen in the case and control groups according to age and gender distribution (p:0.698, p:0.340). Native thiol value in the case group was significantly lower than the control group (p:0.014). The 8-OHdG value in the case group was significantly higher than the control group (0.015). The native thiol value in the case group with a BMI change of ≥13 was significantly higher than the group with BMI change of <13 (p:0.034). The 8-OHdG value with BMI change ≥13 was significantly lower than the group with BMI change <13 (p:0.045). The proportion of patients with a BMI change of ≥13 and a post-operative follow-up period of more than 4 years was significantly lower than the group with a BMI change of <13 (p:0.002). Conclusion: When the comparison results of 8-OHdG, which is an indicator of oxidative DNA damage, were examined between the groups, it was determined that the 8-OHdG level in the patient group was higher than in obese individuals who did not undergo bariatric surgery. When native thiol levels were examined, it was determined that there were statistically significantly higher native thiol levels in obese patients who did not undergo surgery. This may be an explanation for why oxidative DNA damage is lower in obese individuals who have not undergone surgery. Due to the higher native thiol level in these patients, a stronger antioxidant effect may have reduced oxidized DNA damage. On the other hand, the increase in native thiol levels in the surgery group may be related to the patients continuing their bad eating habits. Although previous studies have shown that oxidative damage level indicators of obese patients are higher than individuals who have undergone bariatric surgery, the result of our study does not support this. Of course, as we mentioned before, this may depend on other factors related to the patients other than surgery. A significant negative correlation was observed between the amount of weight loss and the disulfide/native thiol ratio, and a significant positive correlation with the native thiol/total thiol ratio in those who underwent surgery. The relationship between increased weight loss after surgery and native thiol elevation can be interpreted as resulting in antioxidant status activation and oxidative stress reduction. We determined that oxidative DNA damage increased in these patients compared to obese individuals, as the diet habits returned to their previous state in patients more than 1 year postoperatively, and a BMI over 30 indicates that these patients gained weight again. Again, native thiol levels were found to be high in those who had bariatric surgery and whose BMI decreased more. Based on this, it can be evaluated that patients with significant BMI loss are exposed to less oxidative stress with a stronger antioxidant effect. Key Words: Obesity, BMI, 8-hydroxy-2-deoxyguanosine, NADPH oxidase 2, NADPH oxidase 4, Total Thiol, Native Thiol