Correlation between ERα receptor expression, epitheliocyte nucleus electrokinetic activity, and vaginal microbiocenosis state in vulvovaginal atrophy

Introduction. Genitourinary menopause syndrome (GUSM) significantly worsens the quality of life of postmenopausal women. Traditional diagnostic approaches based primarily on clinical manifestations provide no precisely assessed severity of pathomorphological disorders.

Aim: to study a relationship between estradiol level, estrogen receptors (ERα) state, the functional activity of vaginal epithelial cells, as well as the characteristics of the vaginal microbiome.

Materials and Methods. An interventional cross-sectional comparative study with 148 women was conducted. Depending on the present or absent of pathognomonic complaints and clinical signs of vulvovaginal atrophy (VVA), 113 postmenopausal patients were divided into 3 clinical groups: group 1 – 42 patients with VVA and reported subjective clinical symptoms and complaints; group 2 – 36 patients with VVA, visual signs of the atrophic process and no subjective clinical symptoms and complaints; group 3 – 35 healthy postmenopausal women without VVA signs. Control group consisted of 35 healthy women of reproductive age. The study used electrochemiluminescence immunoassay (ECLIA) to determine the level of blood plasma estradiol, molecular biological analysis (real-time polymerase chain reaction) – to study the vaginal microflora using the Femoflor-16 method. An assessment of epitheliocyte nucleus electrokinetic activity (ENEA) was carried out according to V.G. Shakhbazov et al. (1986) microelectrophoresis method, as well as an immunohistochemical (IHC) study of vaginal wall biopsies – to determine ERα expression using monoclonal antibodies as well as visualization systems and assessment conducted by Allred system.

Results. Our data showed that the pH of vaginal secretions increases from control group to groups with VVA, indicating a decreased acidity. In group 4 (reproductive age women), the pH was 3.89, significantly lower than in other groups (p < 0.001). In group 3 (postmenopause without VVA), the pH was higher than in control, but lower than that of in group with VVA (p < 0.001). Groups 1 and 2 (with VVA) have the highest pH, with group 1 (symptomatic) being higher than in group 2 (p < 0.001). In addition, there were also data obtained on microbiota state in the studied patients. All women (100.0 %) from group 1 had severe dysbiosis; in group 2, 25 % had severe dysbiosis, and 75 % had moderate dysbiosis. In group 3, individuals were distributed roughly equal proportions: normocenosis and normocenosis with signs of dysbiosis in 42.8 %, and 14.2 % with moderate dysbiosis. The maximum estradiol concentration in control group was 161.7 pg/ml, significantly higher than the others (p < 0.001). No significant differences between the groups with VVA were found. The ERa level decreased in groups with VVA: in asymptomatic vs. symptomatic patients with VVA, it was higher (p < 0.001). Women without VVA had the highest ERa level. ENEA decreased from control (53.9 %) to groups with VVA, especially in symptomatic subjects (up to 3.88 %). In patients from group 3, it was higher than in study groups with VVA (p < 0.001). Statistical analysis has shown that absolute normocenosis is associated with higher ENEA level compared to dysbiosis. The high correlation between ERa and ENEA shows that such indicators are interconnected and closely related to mucosal condition. The regression model showed that estradiol level and epithelial parameters were important for control group, while ENEA level and acidity dominated in VVA groups.

Conclusion. ENEA is a sensitive and non-invasive marker closely related to vaginal microbiota state. Its magnitude decreases in microbiota disorders and reaches 41.2 % in absolute normocenosis, mirroring a good mucosal condition. In postmenopause, even a conditional normocenosis is accompanied by ENEA decreased down to 35.2 %, which may suggest preclinical changes. With moderate dysbiosis, the indicators decrease by 3–4 times, and with severe dysbiosis – by more than 15 times, indicating seriously altered homeostasis. Statistical inter-group significance confirms the ENEA ability to objectively assess the degree of microbiological disorders. A level below 35 % highlights deviation from normal range, even without clinical symptoms. Magnitude of 2–10 % indicate severe dysbiosis requiring correction. Altered relationship between the parameters may suggest severity of the process and portend a poor response to treatment. Intensive combination therapy is recommended for patients with symptomatic VVA. With "silent" atrophy, therapy aimed at improving epithelial condition is sufficient, without significant changes in the hormonal background. Evidence suggests that preventive maintenance of microflora and acidity is important in postmenopausal women. For the first time, it is proposed to use ENEA as a parameter that bridges molecular disorders and clinical as well as microbiological manifestations of VVA, which lay a foundation for novel stratification and diagnosis system as well as differentiated treatment depending on regulatory relationships at the tissue level.

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