Flavia Angelini

Selective Activation of Peroxisome Proliferator–Activated Receptor (PPAR)α and PPARγ Induces Neoangiogenesis Through a Vascular Endothelial Growth Factor–Dependent Mechanism

OBJECTIVE—Peroxisome proliferator–activated receptors (PPARs) are therapeutic targets for fibrates and thiazolidinediones, which are commonly used to ameliorate hyperlipidemia and hyperglycemia in type 2 diabetes. In this study, we evaluated whether activation of PPARα and PPARγ stimulates neoangiogenesis. RESEARCH DESIGN AND METHODS—We used selective synthetic PPARα and PPARγ agonists and investigated their angiogenic potentials in vitro and in vivo. RESULTS—Activation of PPARα and PPARγ leads to endothelial tube formation in an endothelial/interstitial cell co-culture assay. This effect is associated with increased production of the angiogenic cytokine vascular endothelial growth factor (VEGF). Neovascularization also occurs in vivo, when PPARα and PPARγ agonists are used in the murine corneal angiogenic model. No vascular growth is detectable when PPARα and PPARγ agonists are respectively used in PPARα knockout mice and mice treated with a specific PPARγ inhibitor, demonstrating that this angiogenic response is PPAR mediated. PPARα- and PPARγ-induced angiogenesis is associated with local VEGF production and does not differ in extent and morphology from that induced by VEGF. In addition, PPARα- and PPARγ-induced in vitro and in vivo angiogenesis may be significantly decreased by inhibiting VEGF activity. Finally, in corneas treated with PPARα and PPARγ agonists, there is increased phosphorylation of endothelial nitric oxide synthase and Akt. CONCLUSIONS—These findings demonstrate that PPARα and PPARγ activation stimulates neoangiogenesis through a VEGF-dependent mechanism. Neoangiogenesis is a crucial pathological event in type 2 diabetes. The ability of PPARα and PPARγ agonists to induce neoangiogenesis might have important implications for the clinical and therapeutic management of type 2 diabetes.

Sonic Hedgehog Regulates Angiogenesis and Myogenesis During Post-Natal Skeletal Muscle Regeneration

Sonic hedgehog (Shh) is a morphogen‐regulating crucial epithelial‐mesenchymal interactions during embryonic development, but its signalling pathway is considered generally silent in post‐natal life. In this study, we demonstrate that Shh is de novo expressed after injury and during regeneration of the adult skeletal muscle. Shh expression is followed by significant up‐regulation of its receptor and target gene Ptc1 in injured and regenerating muscles. The reactivation of the Shh signalling pathway has an important regulatory role on injury‐induced angiogenesis, as inhibition of Shh function results in impaired up‐regulation of prototypical angiogenic agents, such as vascular endothelial growth factor (VEGF) and stromal‐derived factor (SDF)‐1alpha, decreased muscle blood flow and reduced capillary density after injury. In addition, Shh reactivation plays a regulatory role on myogenesis, as its inhibition impairs the activation of the myogenic regulatory factors Myf‐5 and MyoD, decreases the up‐regulation of insulin‐like growth factor (IGF)‐1 and reduces the number of myogenic satellite cells at injured site. Finally, Shh inhibition results in muscle fibrosis, increased inflammatory reaction and compromised motor functional recovery after injury. These data demonstrate that the Shh pathway is functionally important for adult skeletal muscle regeneration and displays pleiotropic angiogenic and myogenic potentials in post‐natal life. These findings might constitute the foundation for new therapeutic approaches for muscular diseases in humans.

Association between IL-6 and MMP-3 gene polymorphisms and adolescent idiopathic scoliosis : A case-control study

Study Design. Case-control study. Objective. As inflammation plays a key role in the etiology of intervertebral disc degeneration, we suggest a possible contribution of pro-inflammatory gene polymorphisms in the pathogenesis of adolescent idiopathic scoliosis (AIS). Summary of Background Data. The nucleus pulposus of scoliotic discs responds to exogenous stimuli by secreting interleukin-6 (IL-6) and other inflammatory cytokines. The association between matrix metalloproteinases (MMPs) and disc degeneration has been reported by several investigators. A human MMP-3 promoter 5A/6A gene polymorphism regulates MMP-3 genes expression, while the G/C polymorphism of the promoter region of IL-6 gene influences levels and functional activity of the IL-6 protein. Methods. We conducted a case-control study to investigate whether the 5A/6A polymorphism of the MMP-3 gene and the G/C polymorphism of the promoter region of IL-6 gene were associated with susceptibility to AIS. Results. The frequency of the 5A/5A genotype of MMP-3 gene polymorphism in patients with scoliosis was almost 3 times higher than in controls (30.2% vs. 11.2%, p 0.001), and the frequency of the G/G genotype of IL-6 gene polymorphism in patients with scoliosis was almost 2 times higher than in controls (52.8% vs. 26.2%, P < 0.001). 5A/5A genotype of MMP-3 gene polymorphism and G/G genotype of IL-6 gene polymorphism are independently associated with a higher risk of scoliosis (odds ratio, respectively, 3.34 and 10.54). Conclusion. This is the first study that has evaluated the possibility that gene variants of IL-6 and MMPs might be associated with scoliosis and suggests that MMP-3 and IL-6 promoter polymorphisms constitute important factors for the genetic predisposition to scoliosis.

Pro‐inflammatory genetic profiles in subjects with peripheral arterial occlusive disease and critical limb ischemia

Objectives.  Single nucleotide polymorphisms in genes encoding inflammatory molecules may determine genetic profiles associated with increased risk of development and progression of cardiovascular diseases. In this study, we evaluated distribution and reciprocal interaction of a set of functionally important polymorphisms of genes encoding prototypical inflammatory molecules in subjects with peripheral arterial occlusive disease (PAOD) and critical limb ischemia (CLI). We also investigated whether synergistic interactions between these pro‐inflammatory gene polymorphisms influence the risk of PAOD and CLI.

Effect of Proinflammatory Gene Polymorphisms on the Risk of Alzheimer's Disease

Background: A number of studies associate Alzheimers disease (AD) with APOE polymorphism and alleles which favor the increased expression of immunological mediators such as cytokines or acute-phase proteins. Objective: In this study we evaluated the distribution of a set of functionally important polymorphisms of genes encoding prototypical inflammatory molecules in individuals with AD. We also investigated whether a synergistic effect of these proinflammatory gene polymorphisms on the risk of AD could be hypothesized. Methods: In a genetic association study that included 533 AD patients and 713 controls, the following gene polymorphisms were analyzed: C-reactive protein (CRP) 1059 G/C, interleukin 6 (IL6) -174 G/C, interleukin 1β (IL1B) -31 T/C, tumor necrosis factor α (TNF-α) -308 G/A, macrophage migration inhibitory factor (MIF) -173 G/C, monocyte chemoattractant protein 1 (CCL2) -2518 A/G, intercellular adhesion molecule 1 (ICAM1) 469 E/K, E-selectin (SELE) Ser128Arg, macrophage inflammatory protein 1α (CCL3) -906 T/A, matrix metalloproteinase 3 (MMP3) -1171 5A/6A and matrix metalloproteinase 9 (MMP9) -1562 C/T. Results: We found that IL6, IL1B, CCL2, CCL3, SELE, ICAM1, MMP3, and MMP9 gene polymorphisms were significantly and independently associated with AD. The association remained significant even after the Bonferroni correction. We also found that these proinflammatory polymorphisms were associated with different levels of risk for AD, depending on the number of high-risk genotypes concomitantly carried by a given individual. Conclusion: Proinflammatory genotypes might influence the development and progression of AD exerting a potential synergistic effect.

Assessment of the Genetic Effects of Polymorphisms in the Osteoprotegerin Gene, TNFRSF11B, on Serum Osteoprotegerin Levels and Carotid Plaque Vulnerability

Background and Purpose— Osteoprotegerin (OPG) is a secretory glycoprotein which belongs to the tumor necrosis factor receptor family. Various mechanisms have been suggested by which calcification might alter atherosclerotic plaque stability, but the significance of this intimal calcification is controversial. High concentrations of OPG have been associated with the presence of vascular and cardiovascular diseases. This study was designed to assess the association between gene polymorphisms of the OPG gene (TNFRSF11B), the serum OPG level, and plaque stability in patients with carotid atherosclerosis. Methods— We studied 177 patients with internal carotid artery stenosis who underwent carotid endarterectomy and also 303 controls. Carotid endarterectomy samples removed from patients were assessed by immunohistochemistry. Concentrations of OPG were measured and gene polymorphisms were examined by polymerase chain reaction and restriction enzyme analysis and were compared, initially between patients with carotid atherosclerosis and controls, and subsequently between stable and unstable carotid plaques. Results— We found that the GG genotype of the T245G polymorphism, the CC genotype of the T950C polymorphism, and the CC genotype of the G1181C polymorphism were significantly higher in patients with carotid plaque than in controls (21.5% versus 10.9% , P<0.01; 15.8% versus 7.6%, P<0.01; and 20.3% versus 10.9%, P<0.01, respectively) and that these polymorphisms were associated with high serum OPG levels (4.02 [3.07] versus 2.94 [1.81] pmol/L; P<0.01), which were significantly higher in patients with unstable atherosclerotic plaques (5.86 [4.02] versus 3.53 [1.87] pmol/L; P<0.01). Conclusions— The TNFRSF11B gene polymorphisms studied are associated with high serum OPG levels and might be potential markers for plaque instability.

Peroxisome Proliferator-Activated Receptor Alpha Is Crucial for Iloprost-Induced in vivo Angiogenesis and Vascular Endothelial Growth Factor Upregulation

We have previously demonstrated that iloprost, a stable prostacyclin (PGI2) analogue, induces angiogenesis in vivo, through a vascular endothelial growth factor (VEGF)-dependent mechanism. In this study, we demonstrate that iloprost-induced angiogenesis and VEGF upregulation are modulated by peroxisome proliferator-activated receptor-α (PPARα), a ligand-inducible transcription factor that belongs to the nuclear hormone receptor superfamily and plays multiple biological activities in the vascular system. We show that iloprost is unable to induce angiogenesis in mice lacking the PPARα gene (PPARα–/– mice). Likewise, iloprost-induced VEGF upregulation is absent in PPARα–/– mice. In contrast, iloprost induces a robust angiogenic response in wild-type mice, along with local upregulation of VEGF. Importantly, mice lacking the PPARα gene exhibit a normal angiogenic response to VEGF, indicating that the absence of PPARα does not result in a general impairment of angiogenesis, but specifically affects the ability of iloprost to induce angiogenesis. Our data demonstrate unexpected functional relationships between the PGI2 system and the PPAR signaling pathway and shed new light on the molecular mechanisms involved in iloprost-induced angiogenesis.

Cilostazol promotes angiogenesis after peripheral ischemia through a VEGF-dependent mechanism

BACKGROUND/OBJECTIVES Cilostazol has been found to be effective for the treatment of intermittent claudication (IC). This compound has several beneficial effects on platelet aggregation, serum lipids and endothelial cells, but how these might relate to improvements in walking is not entirely understood. The aim of this work was to investigate the effects of cilostazol on angiogenic response in a murine model of peripheral ischemia and to clarify the underlying molecular mechanisms of that response. METHODS We studied ischemia-induced neovascularization in the ischemic hindlimb of cilostazol-treated and untreated control mice. RESULTS We found that the perfusion recovery was significantly improved in treated compared with control mice. Interestingly, there was a higher level of circulating endothelial progenitor cells (EPCs) in mice treated with cilostazol than in untreated mice. Furthermore, cilostazol administration resulted in upregulation of granulocyte colony-stimulating factor (G-CSF) and vascular endothelial growth factor (VEGF) in the ischemic muscle of treated mice. Finally, inhibiting VEGF activity significantly reduced cilostazol-induced angiogenesis. CONCLUSIONS The results of this study show that cilostazol administration enhances collateral blood flow in the ischemic hindlimbs of mice through a VEGF-dependent mechanism. These data may help to explain the beneficial effects that this drug has on patients with peripheral arterial disease (PAD) and IC.

Human cord blood endothelial progenitors promote post-ischemic angiogenesis in immunocompetent mouse model

BACKGROUND Human cord blood (CB) endothelial colony forming cells (ECFCs) are endowed with high vascular regenerative ability in immunodeficient mice, but their immunogenicity and susceptibility to rejection in immunocompetent models has yet to be explored. METHODS We injected CB ECFCs in non-immuno-suppressed C57BL/6J mice after having induced the hindlimb ischemia and we investigated their contribution to the recovery from the ischemic injury. Human ECFCs (hECFCs) were administered by intramuscular injection and hindlimb blood perfusion was measured by laser Doppler analysis at 7-day intervals for 28days after treatment. Mice were sacrificed after 7 and 28days and immunohistochemistry for specific human (CD31) and mouse (von Willebrand factor) endothelial antigens was carried out. Before euthanasia, blood samples to assess cytokines and angiogenic growth factor levels were collected. RESULTS Mice injected with hECFCs showed a prompter and greater recovery of blood flow than controls. Several endothelial cells of human origin were detected at day7 after injection and their number declined progressively. Likewise, a progressive increase of mouse-derived vascular structures were observed, paralleled by the amplified endogenous production of various soluble mediators of angiogenesis, including Vascular Endothelial Growth Factor and Fibroblast Growth Factor. CONCLUSIONS Overall, our findings are consistent with the hypothesis that human ECFCs might expand the endogenous vascular repair potential of recipients and support their possible HLA-independent unconventional use.

An Overview of Diagnosis of Primary Autoimmune Hypophysitis in a Single Prospective Monocentric Experience.

Background: Autoimmune hypophysitis is a rare disease with a natural progression that is not well known. Aim: To collect representative data on clinical features of autoimmune hypophysitis and better characterize the disease. Patients and Methods: A prospective single-center study was designed. Autoimmune hypophysitis-affected patients evaluated from 2011 at our tertiary care Pituitary Unit were enrolled. After ruling out other pituitary masses and secondary causes of hypophysitis, autoimmune hypophysitis was the diagnosis of exclusion. Autoimmune hypophysitis was classified as adenohypophysitis, panhypophysitis, and infundibuloneurohypophysitis according to clinical and neuroradiological findings. Results: A total of 21 patients met the inclusion criteria: 9 were diagnosed with adenohypophysitis, 4 with panhypophysitis, and 8 with infundibuloneurohypophysitis. The frequency of secondary hypoadrenalism was similar in adenohypophysitis, panhypophysitis, and infundibuloneurohypophysitis. Growth hormone deficit and secondary hypogonadism occurred more frequently in infundibuloneurohypophysitis than in adenohypophysitis and panhypophysitis (p = 0.009; p = 0.04). All cases of multiple pituitary secretion deficits occurred in cases of infundibuloneurohypophysitis (p = 0.04). No correlations between hypophysitis subtype and anti-pituitary and anti-hypothalamus autoantibodies were found. A higher frequency of extractable nuclear antigens (ENA) and anti-nuclear antibodies (ANA) was found in cases of panhypophysitis (OR 5.0, 95% CI 0.86-28.8, p < 0.001, and OR 1.8, 95% CI 1.1-3.2, p = 0.02, respectively) as compared to adenohypophysitis and infundibuloneurohypophysitis. Conclusion: Infundibuloneurohypophysitis should be taken into account in the etiological diagnosis of hypopituitarism, particularly if it is associated with diabetes insipidus and in cases of growth hormone deficit, secondary hypogonadism, or multiple hormone deficits. Contrast-enhanced MRI is crucial for the clinical and noninvasive diagnosis of hypophysitis. Screening for autoantibodies, particularly anti-ENA and anti-ANA, is strongly suggested in the clinical context of hypophysitis.