Expression levels of haem oxygenase-1 in the omental adipose tissue and peripheral blood mononuclear cells of women with polycystic ovary syndrome

BACKGROUND: Haem oxygenase (HO)-I, an enzyme that degrades haem, plays a key role in the regulation of the inflammatory response and insulin resistance. The aim of this study was to evaluate the role of HO-I in the regulation of insulin resistance and glucose tolerance in women with polycystic ovary syndrome (PCOS). METHODS: Omental adipose tissue and human peripheral blood mononuclear cells (PBMCs) from seven women with PCOS and five healthy controls, matched for BMI and age, were analysed using western blotting and the real-time PCR. RESULTS: Women with PCOS were found to have significantly higher fasting and 2-h insulin levels, a significantly higher homeostasis model assessment insulin resistance index and a lower fasting glucose-to-insulin ratio (G 0 /I 0 ) than the controls. The level of HO-I protein in omental fat (P = 0.002), and the expression of HO-I mRNA in omental fat and PBMCs from the women with PCOS were significantly lower (P = 0.002 and 0.05, respectively) than those of the controls. The expression of adiponectin mRNA in omental fat was also significantly lower (P = 0.02) in the women with PCOS than in the controls. However, there were no significant differences in the expression of tumour necrosis factor-α or interleukin-6 between the two groups. The level of HO-I protein showed a significant positive correlation with the expression of HO-I mRNA (r 2 = 0.786, P = 0.037) and adiponectin mRNA (r 2 = 0.7276, P < 0.05). Serum insulin and glucose levels and BMI showed a significant negative correlation with the level of HO-I (P < 0.05). CONCLUSIONS: Our results suggest that the HO-I―adiponectin axis may be associated with the regulation of insulin resistance and glucose intolerance in women with PCOS.