Serum levels and significance of HIF-1α and HIF-2α in healthy Tibetan and Han residents at different altitudes

Abstract

To explore the serum levels and significance of hypoxic inducible factor (HIF)-1α and HIF-2α in Tibetan and Han residents living at different altitudes. A total of 100 healthy adults of Han in plain (altitude 5 m, group P) and Tibetan and Han at moderate altitude (2260 m, groups M1 & M2) and high altitude (4380 m, groups H1 & H2) (n = 20 each) were selected from June 2010 to August 2010. Venous blood samples were collected in the morning. The serum concentrations of HIF-1α and HIF-2α were measured with enzyme-linked immunosorbent assay (ELISA) to analyze the correlations of HIF-1α and HIF-2α with arterial partial pressure of oxygen (PaO2) and hemoglobin (Hb). The level of HIF-1α in group H2 ( (6.06 ± 1.85) µg/L) was higher than that in groups P ( (4.56 ± 0.85) µg/L, P < 0.05) , M1 ((4.41 ± 1.05) µg/L, P < 0.01) and M2 ( (4.59 ± 1.03) µg/L, P < 0.05) . The level of HIF-1α in group H1 ( (5.27 ± 0.98) µg/L) was higher than that in group M1 (P < 0.05) . The level of HIF-2α in group H2 ((0.83 ± 0.48) µg/L) was higher than that in groups P ((0.33 ± 0.11) µg/L, P < 0.01), M1 ((0.14 ± 0.06 )µg/L, P < 0.01) and M2( (0.24 ± 0.11) µg/L, P < 0.01) . The level of HIF-2α in group M1 was lower than that in groups P (P < 0.01) and M2 (P < 0.01). The level of HIF-2α in group H1((0.18 ± 0.16)µg/L) was lower than that in groups P (P < 0.05) and H2 (P < 0.01) . The levels of HIF-1α and HIF-2α were negatively correlated with PaO2 (r = -0.475, -0.551, both P < 0.01) and positively with Hb in Han groups (r = 0.433, 0.463, all P < 0.01). The levels of HIF-1α and HIF-2α had no correlation with PaO2 in Tibetan groups (r = -0.270, -0.198, both P > 0.05). No correlation existed between HIF-1α and Hb in Tibetan. A positive correlation existed between HIF-2α and Hb in Tibetan (r = 0.325, P < 0.01). The changes of HIF-1α and HIF-2α vary for Tibetan and Han residents at different altitudes. And the level of HIF-2α is consistent with the change of Hb. As compared with HIF-1α, HIF-2α may play a more important role in regulating Hb.