Tumor necrosis factor inhibitors as novel therapeutic tools for vascular remodeling diseases.

Vascular remodeling diseases (VRDs) are characterized by enhanced inflammation and proliferative and apoptosis-resistant vascular smooth muscle cells (VSMCs). The sustainability of this phenotype has been attributed in part to the activation of the transcription factor hypoxia-inducible factor-1 (HIF-1). There is evidence that circulating cytokines can act as HIF-1 activators in a variety of tissues, including VSMCs. Increased circulating tumor necrosis factor (TNF) levels have been associated with vascular diseases, but the mechanisms involved remain unknown. We hypothesized that increased circulating levels of TNF promotes VRDs by the activation of HIF-1, resulting in VSMC proliferation and resistance to apoptosis. Circulating TNF levels were significantly increased in patients with vascular diseases (n = 19) compared with healthy donors (n = 15). Using human carotid artery smooth muscle cells (CASMCs), we demonstrated that TNF (100 ng/ml) activates HIF-1 (HIF-1α expression), leading to increased CASMC proliferation (Ki-67 and PCNA staining) and resistance to mitochondrial-dependent apoptosis [tetramethylrhodamine methyl ester perchlorate (TMRM), terminal deoxynucleotide transferase-mediated dUTP nick end labeling (TUNEL), annexin-V staining]. In vivo, TNF inhibition using polyethylene glycol coupled with TNF membrane receptor 1 (PEGsTNFR1), a soluble TNF receptor inhibiting circulating TNF, prevented carotid artery postinjury media remodeling and neointima development in rats. This effect was associated with lowered HIF-1 activation and decreased CASMC proliferation. In conclusion, we demonstrate for the first time that the inhibition of the TNF/Akt/HIF-1 axis prevents vascular remodeling. TNF inhibitors may therefore represent new and interesting therapeutic tools against VRDs.

HIF-1 inhibition decreases systemic vascular remodelling diseases by promoting apoptosis through a hexokinase 2-dependent mechanism.

AIMS: Vascular remodelling diseases are characterized by the presence of proliferative and apoptosis-resistant vascular smooth muscle cells (VSMC). There is evidence that pro-proliferative and anti-apoptotic states are characterized by metabolic remodelling (a glycolytic phenotype with hyperpolarized mitochondria) involving Akt pathway activation by circulating growth factors. Hypoxia-inducible factor-1 (HIF-1) is involved in different vascular diseases. Since this transcription factor is implicated in metabolic responses, we hypothesized that HIF-1 activity could be involved in vascular remodelling in response to arterial injury. METHODS AND RESULTS: Our findings indicate that growth factors, such as platelet-derived growth factor (PDGF), activate the Akt pathway (measured by immunoblot) in human carotid artery VSMC. Activation of this pathway increased HIF-1 activation (measured by immunoblot), leading to increased glycolysis in VSMC. Expression and mitochondrial activity of hexokinase 2 (HXK2), a primary initiator of glycolysis, are increased during HIF-1 activation. The mitochondrial activity of HXK2 in VSMC led to the hyperpolarization of mitochondrial membrane potential (measured by tetramethylrhodamine methyl-ester perchlorate) and the suppression of apoptosis (measured by TUNEL assay and 3 activity), effects that are blocked by HIF-1 inhibition. Additionally, HIF-1 inhibition also decreased VSMC proliferation (proliferating cell nuclear antigen and Ki-67 assays). In vivo, we demonstrate that localized HIF-1 inhibition, using a dominant-negative HIF-1α adenoviral construct, prevented carotid artery post-injury remodelling in rats. CONCLUSION: We propose that HIF-1 is centrally involved in carotid artery remodelling in response to arterial injury and that localized inhibition of HIF-1 may be a novel therapeutic strategy to prevent carotid stenosis.