The status of antioxidative system in pregnant women infected with human papilloma virus

Abstract

Background. The concentration of reduced (GSH), oxidized (GSSG) and total (GSH + GSSG) glutathione, the level of malondialdehyde (MDA), and the general antioxidant activity (GAA) was determined in blood plasma and cervicovaginal washing fluid of pregnant women infected and non-infected with human papilloma virus (HPV). Materials and methods. The population of 213 pregnant women visiting one of the Centers of the Central Outpatient Clinic of Vilnius (Lithuania) in 2008–2010 was included in the study. These women were examined for HPV infection and its type. The tests were performed in the first and third trimesters of pregnancy in blood plasma and cervicovaginal washing fluid. The MDA level was tested by the thiobarbituric acid assay. The amount of glutathione forms was determined using a recycling system with 5,5’-dithiobis 2-nitrobenzoic acid and glutathione reductase. General antioxidant activity (GAA) was measured by Tween 80 oxidation in a specific test. All parameters were analyzed spectrophotometrically. Results. The concentration of all glutathione forms and GAA reduced during pregnancy, while the MDA level was enhanced in the blood plasma of all women included in the analysis. Only two of these parameters changed in the cervicovaginal washing fluid. No significant change of GAA was determined comparing groups of women while considering HPV infection. The GSH / GSSG ratio significantly increased in HPV-negative and decreased in HPV-positive women. While comparing HPV-positive and HPV-negative women of similar age, no significant difference of any parameter was found in cervicovaginal washing fluid and in blood plasma in the third trimester. In the first trimester the GSSG level was significantly lower, the GSH level was higher, and the GSH / GSSG ratio was twice higher in HPV-infected women. All pregnant women were compared with non-pregnant women to confirm the influence of pregnancy on the MDA level. In the first trimester, this parameter for pregnant women was close to that of non-pregnant women, while with the developing pregnancy the MDA level increased 1.6 times. No significant difference in the parameter was determined for pregnant women with HPV infection. Conclusions. A decrease of GSH concentration and an increase of MDA level in blood plasma with the development of pregnancy confirmed the presence of a general oxidative stress. The lower levels of GSH and GSH + GSSG in the cervicovaginal washing fluid, if to compare the two trimesters of pregnancy, can be considered as markers of a local oxidative stress. HPV infection depressed the antioxidative system in general and did not affect it at the local level. Systemic oxidative stress, rather than HPV infection, influenced the lipid peroxidation process during pregnancy. The level of MDA is recommended to be tested also during a normal pregnancy, although this parameter should not be considered as an additional biomarker of cervical carcinoma risk. Changes of the antioxidative system variables could induce a deep oxidative imbalance during a pathological pregnancy, and oxidative stress might cause a persistent HPV infection, suggesting the importance of the additional screening of HPV-infected women after delivery. Keywords: HPV infection, pregnancy, antioxidative system