Abnormal expression of HSP70 may contribute to PCOS pathology

The mechanism of the pathological change of polycystic ovary syndrome (PCOS) is still unclear. Previous studies have shown that PCOS is a chronic nonspecific low-grade inflammatory condition, and that heat shock protein (HSP)70 has a potent anti-inflammatory property. So the aim of this study is to investigate the correlation between HSP70 and the hormones and inflammatory factors and to find out the role of HSP70 in the pathogenesis of PCOS.

Twenty female Sprague-Dawley (SD) rats (aged 23 days and weighted 80-90 g) were randomly divided into two groups (n = 10 per group), PCOS group and control group. PCOS group were subcutaneously injected with 6 mg/100 g dehydro-epiandrosterone (DHEA) for 20 consecutive days, the control group were subcutaneously injected with a solvent of equivalent amount. All the samples were collected in the morning fasting state, 12 h after the last administration. Histological examinations of ovarian tissues were analyzed. Hormone levels and inflammatory factors levels were measured by enzyme-linked immunosorbent assay (ELISA) kits.

Serum concentrations of testosterone (T) and luteinizing hormone (LH) were significantly higher in the PCOS group than the control group (P < 0.001), but the concentrations of estradiol (E₂), follicle stimulating hormone (FSH) and insulin didn't show significant difference between these two groups. All the concentrations of inflammatory factors including C-reactive protein (CRP), interleukin (IL)-6, IL-18, and tumor necrosis factor (TNF)-α. were significantly higher in PCOS group than the control group (P < 0.001). The expressions of HSP70 were significantly lower in serum but higher in ovarian tissues in the PCOS group than the control group. Spearman rank correlation analysis showed strong negative correlation of serum HSP70 levels with T, LH and all the detected inflammatory factors.

The abnormal expression of HSP70 correlated with testosterone and inflammatory factors, which indicates that HSP70 may play an important role in PCOS pathology.