Hydrogen sulphide induces HIF-1α and Nrf2 in THP-1 macrophages

• Hydrogen sulphide (H2S) releasing compounds are potential novel drugs.
• H2S stabilises HIF-1α protein in THP-1 macrophages under normal oxygen conditions.
• H2S inhibits cytokine production and NF-κB activation, but it induces Nrf2/HO-1.
• p38 MAPK seems to be involved in H2S mediated activation of HIF-1α/Nrf2 pathways.
• Thus, H2S may induce cell survival and antioxidant signalling pathways.

The transcription factor HIF-1α regulates the adaptive response of cells to hypoxia and oxidative stress. In addition, an important regulatory role for HIF-1α in immune reactions and inflammation is suggested. The present study attempts to investigate the effect of the gaseous signalling molecule hydrogen sulphide (H2S) on HIF-1α in THP-1 macrophages using the slow H2S releasing donor GYY4137.We found that H2S induced HIF-1α protein accumulation in THP-1 macrophages in a concentration-dependent manner. Western blot analysis of cell fractions showed that HIF-1α protein translocates into the nucleus and leads to an increase of its target protein glucose transporter-1 (GLUT-1). Activation of nuclear factor-κB (NF-κB), as well as secretion of the pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-6 (IL-6), were reduced in the presence of H2S. These findings indicate that HIF-1α accumulation due to H2S was not triggered by the NF-κB pathway. The antioxidant pathway Nrf2/HO-1 (nuclear factor erythroid 2-related factor 2/heme oxygenase-1) was activated by H2S. Inhibition of the p38 mitogen-activated protein kinase (MAPK) reversed H2S mediated effects, suggesting that the p38 MAPK pathway may be involved in H2S induced HIF-1α/Nrf2 signalling pathways.