Bone Like Arterial Calcification in Femoral Atherosclerotic Lesions: Prevalence and Role of Osteoprotegerin and Pericytes.

OBJECTIVE/BACKGROUND: Arterial calcification, a process that mimics bone formation, is an independent risk factor of cardiovascular morbidity and mortality, and has a significant impact on surgical and endovascular procedures and outcomes. Research efforts have focused mainly on the coronary arteries, while data regarding the femoral territory remain scarce. METHODS: Femoral endarterectomy specimens, clinical data, and plasma from a cohort of patients were collected prospectively. Histological analysis was performed to characterize the cellular populations present in the atherosclerotic lesions, and that were potentially involved in the formation of bone like arterial calcification known as osteoid metaplasia (OM). Enzyme linked immunosorbent assays and cell culture assays were conducted in order to understand the cellular and molecular mechanisms underlying the formation of OM in the lesions. RESULTS: Twenty-eight of the 43 femoral plaques (65%) displayed OM. OM included osteoblast and osteoclast like cells, but very few of the latter exhibited the functional ability to resorb mineral tissue. As in bone, osteoprotegerin (OPG) was significantly associated with the presence of OM (p = .04). Likewise, a high plasma OPG/receptor activator for the nuclear factor kappa B ligand (RANKL) ratio was significantly associated with the presence of OM (p = .03). At the cellular level, there was a greater presence of pericytes in OM+ compared with OM- lesions (5.59 ± 1.09 vs. 2.42 ± 0.58, percentage of area staining [region of interest]; p = .04); in vitro, pericytes were able to inhibit the osteoblastic differentiation of human mesenchymal stem cells, suggesting that they are involved in regulating arterial calcification. CONCLUSION: These results suggest that bone like arterial calcification (OM) is highly prevalent at femoral level. Pericyte cells and the OPG/RANK/RANKL triad seem to be critical to the formation of this ectopic osteoid tissue and represent interesting potential therapeutic targets to reduce the clinical impact of arterial calcification.

Treatment of TASC C and D Femoropoliteal Lesions with Paclitaxel eluting Stents: 12 month Results of the STELLA-PTX Registry.

OBJECTIVE: The aim was to evaluate the safety and the efficacy of primary stenting with paclitaxel eluting stents for TASC C and D femoropopliteal lesions. METHODS: Patients with TASC C/D de novo femoropopliteal lesions were treated by implanting paclitaxel eluting stents. Patients were included in a single center registry and prospectively followed by clinical and ultrasound evaluation. X-ray of the stented zone was systematically performed 12 months after implantation. The primary endpoint was primary sustained clinical improvement after 12 months. RESULTS: A total of 45 patients (48 limbs) suffering from claudication (25 limbs) or CLI (23 limbs) were enrolled. Lesions were either TASC C (28 limbs) or TASC D (20 limbs). The mean length of the treated segment was 252 ± 90 mm. The mean number of stents was 2.9 ± 1 (2-5). Mean follow up was 12.7 months. No patient was lost to follow up. At 1 year post procedure, primary and secondary sustained clinical improvements were 56.3 ± 7.4% and 80.1 ± 5.9% respectively. Freedom from target lesion and target extremity revascularization were 63.6% and 90.1%, respectively. Primary and secondary patency rates were 52.5% and 79.6%. One year primary sustained clinical improvement rates for TASC C/D were 63.3 ± 9.2% and 45.6 ± 11.7%, respectively (p = .34). One year primary sustained clinical improvement rates for claudication/CLI patients were 68 ± 9.3% and 41.6 ± 11.1%, respectively (p = .13). The incidence of in stent re-stenosis and in stent thrombosis were 25% and 14%, respectively. The incidence of stent fracture was 12.5% on a limb basis and 9% on a per stent basis. CONCLUSIONS: The paclitaxel eluting stent did not achieve its goal in terms of prevention of in stent re-stenosis for TASC C/D femoropopliteal lesions. It requires frequent re-interventions during the first year to maintain satisfactory clinical results.

State-of-the-art treatment of common femoral artery disease.

Atherosclerotic common femoral artery (CFA) disease is a well-known and frequent cause of symptomatic peripheral artery disease (PAD). Not so long ago, surgical treatment was considered the gold standard and the main treatment option. Therapeutic advances have, however, provided a wide and suitable armamentarium. These advances concern medical treatment and the direct treatment of lesions by open surgery or endovascular treatment. The aim of this manuscript was to summarize therapeutic updates and to describe the current endovascular and open surgical procedures used to treat common femoral artery disease.

Molecular imaging of macrophage protease activity in cardiovascular inflammation in vivo.

Macrophages contribute pivotally to cardiovascular diseases (CVD), notably to atherosclerosis. Imaging of macrophages in vivo could furnish new tools to advance evaluation of disease and therapies. Proteolytic enzymes serve as key effectors of many macrophage contributions to CVD. Therefore, intravital imaging of protease activity could aid evaluation of the progress and outcome of atherosclerosis, aortic aneurysm formation, or rejection of cardiac allografts. Among the large families of proteases, matrix metalloproteinases (MMPs) and cysteinyl cathepsins have garnered the most interest because of their participation in extracellular matrix remodelling. These considerations have spurred the development of dedicated imaging agents for protease activity detection. Activatable fluorescent probes, radiolabelled inhibitors, and nanoparticles are currently under exploration for this purpose. While some agents and technologies may soon see clinical use, others will require further refinement. Imaging of macrophages and protease activity should provide an important adjunct to understanding pathophysiology in vivo, evaluating the effects of interventions, and ultimately aiding clinical care.

Long-term allograft tolerance is characterized by the accumulation of B cells exhibiting an inhibited profile.

Numerous reports have highlighted the central role of regulatory T cells in long-term allograft tolerance, but few studies have investigated the B-cell aspect. We analyzed the B-cell response in a rat model of long-term cardiac allograft tolerance induced by a short-term immunosuppression. We observed that tolerated allografts are infiltrated by numerous B cells organized in germinal centers that are strongly regulated in their IgG alloantibody response. Moreover, alloantibodies from tolerant recipients exhibit a deviation toward a Th2 isotype and do not activate in vitro donor-type endothelial cells in a pro-inflammatory way but maintained expression of cytoprotective molecules. Interestingly, this inhibition of the B-cell response is characterized by the progressive accumulation in the graft and in the blood of B cells blocked at the IgM to IgG switch recombination process and overexpressing BANK-1 and the inhibitory receptor Fcgr2b. Importantly, B cells from tolerant recipients are able to transfer allograft tolerance. Taken together, these results demonstrate a strong regulation of the alloantibody response in tolerant recipients and the accumulation of B cells exhibiting an inhibited and regulatory profile. These mechanisms of regulation of the B-cell response could be instrumental to develop new strategies to promote tolerance.

Impaired Notch4 activity elicits endothelial cell activation and apoptosis: implication for transplant arteriosclerosis.

OBJECTIVE: Notch signaling pathway controls key functions in vascular and endothelial cells (EC). However, little is known about the role of Notch in allografted vessels during the development of transplant arteriosclerosis (TA). This study investigated regulation of the Notch pathway on cardiac allograft arteriosclerosis and further examined its implication in EC dysfunction. METHODS AND RESULTS: Here we show that, among Notch receptors, Notch2, -3, and -4 transcript levels were markedly downregulated in TA compared to tolerant and syngeneic allografts. TA correlates with high levels of tumor necrosis factor (TNF), transforming growth factor (TGF)beta, and IL10, which consistently decrease Notch4 expression in transplants and cultured ECs. We found that inhibition of Notch activity, reflected by both a reduced CBF1 activity and Hes1 expression, parallels the downregulation of Notch4 expression mediated by TNF in ECs. Notch4 and Hes1 knockdown enhances vascular cell adhesion molecule-1 expression and promotes EC apoptosis. Silencing Notch4 or Hes1 also drastically inhibits repair of endothelial injury. Overall, our results suggest that Notch4 and basal Notch activity are required to maintain EC quiescence and for optimal survival and repair in response to injury. CONCLUSIONS: Together, our findings indicate that impaired Notch4 activity in graft ECs is a key event associated with TA by triggering EC activation and apoptosis.