Adaptive changes in placenta of obese pregnant women - the expression of Bcl-2 and Pim-1

An intensification of inflammatory processes and apoptosis has been observed in pregnant women with abnormally high Body Mass Index (BMI) values. This study aimed to evaluate the expression of the anti-apoptotic protein Bcl-2 (Apoptosis Regulator Bcl-2) in the placenta as a defence mechanism limiting the negative impact of adipose tissue. Additionally, it sought to assess the expression of the protein Pim-1 (Serine/Threonine-Protein Kinase Pim-1), a kinase associated with local inflammation within the placenta induced by excessive maternal adipose tissue.

The evaluation of Pim-1 and Bcl-2 expression was conducted using immunohistochemical (IHC) staining on a tissue microarray (TMA) constructed from 108 placenta samples. In our study, we applied a cross-sectional analysis. We analysed the study population based on pre-pregnancy BMI, BMI at term, and gestational weight gain, categorized according to WHO classifications.

The expression of Bcl-2 in placentas was highest in the group of obese patients and lowest in the group of patients with normal body mass, both before and at the end of pregnancy. However, statistically significant differences in Bcl-2 protein expression levels between the analysed subgroups were observed only when divided according to BMI at the end of pregnancy (p = 0.029). The differences in Pim-1 protein expression intensity in placentas between the groups were not statistically significant. Women with excessive gestational weight gain have a significantly higher level of Pim-1 expression compared to those with insufficient weight gain (p = 0.016). No statistically significant differences were found between the groups regarding Bcl-2 protein expression.

Pregnant women with elevated BMI values showed increased expression of Pim-1 and Bcl-2 proteins in placental tissue, demonstrating the impact of excessive body weight on the development of apoptosis and inflammation in the placenta, as well as the activation of defence mechanisms such as anti-apoptosis.