Glycosylated human oxyhaemoglobin activates nuclear factor‐ κ B and activator protein‐1 in cultured human aortic smooth muscle

Diabetic vessels undergo structural changes that are linked to a high incidence of cardiovascular diseases. Reactive oxygen species (ROS) mediate cell signalling in the vasculature, where they can promote cell growth and activate redox‐regulated transcription factors, like activator protein‐1 (AP‐1) or nuclear factor‐ κ B (NF‐ κ B), which are involved in remodelling and inflammation processes. Amadori adducts, formed through nonenzymatic glycosylation, can contribute to ROS formation in diabetes. In this study, we analysed whether Amadori‐modified human oxyhaemoglobin, glycosylated at either normal (N‐Hb) or elevated (E‐Hb) levels, can induce cell growth and activate AP‐1 and NF‐ κ B in cultured human aortic smooth muscle cells (HASMC). E‐Hb (1 n M –1 μ M ), but not N‐Hb, promoted a concentration‐dependent increase in cell size from nanomolar concentrations, although it failed to stimulate HASMC proliferation. At 10 n M , E‐Hb stimulated both AP‐1 and NF‐ κ B activity, as assessed by transient transfection, electromobility shift assays or immunofluorescence staining. The effects of E‐Hb resembled those of the proinflammatory cytokine tumour necrosis factor‐ α (TNF‐ α ). E‐Hb enhanced intracellular superoxide anions content and its effects on HASMC were abolished by different ROS scavengers. In conclusion, E‐Hb stimulates growth and activates AP‐1 and NF‐ κ B in human vascular smooth muscle by redox‐sensitive pathways, thus suggesting a possible direct role for Amadori adducts in diabetic vasculopathy.British Journal of Pharmacology (2003) 140 , 681–690. doi: 10.1038/sj.bjp.0705483