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  • The following are the supplementary

    2019-07-24

    The following are the supplementary data related to this article.
    Conflicts of interest statement
    Transparency document
    Acknowledgements This research was supported by Grants from University of Basilicata to VI (grant number 3010101), University of Bari to VI (grant number 00405815), and by AIRC to GG (grant number 18737).
    Introduction Angiogenesis is a vital process occurring in tissue development and wound healing in damaged tissues [1]. It is a multistep event that starts when endothelial Norfloxacin (ECs) switch from “quiescent” to “angiogenic” phenotype in response to pro-angiogenic stimuli [2]. Following stimulation, ECs begin to proliferate, invade the extracellular matrix (ECM) thereby contributing to the formation of an immature capillary structure with deposition of a new basement membrane (BM) and pericytes recruitment [3]. Under physiological conditions, angiogenesis is a highly regulated process that is turned on for brief periods and then is completely inhibited [4]. The balanced activity between specific pro- and anti-angiogenic molecules which can activate or stop this process is critical for an optimal angiogenic response [3]. The persistent hyperglycemic milieu related to DM is associated with the onset and progression of micro- and macro-vascular complications, most of which are characterized by impaired vascularization and/or aberrant angiogenesis [5]. A wide number of studies performed both in animals and humans demonstrated that chronic hyperglycemia impairs endothelial function in macro- and micro-vasculature [6]. Indeed, through the activation of several molecular pathways, hyperglycemia induces excessive generation of ROS, increased oxidative stress and reduced vasodilation. Moreover, glucotoxicity induces a low-grade proinflammatory condition, due to the activation of transcription factors such as NF-κB [7]. In the last decade, great interest has been paid to MGO, a major precursor of advanced glycation end products (AGEs) in ECs [8]. MGO mainly originates as a byproduct of glycolysis by non-enzymatic degradation of triosephosphates [9], with a formation rate of about 125 μmol/kg cell mass per day under normoglycemic conditions [10]. The majority of MGO (>99%) is detoxified by the glyoxalase system in healthy conditions [8]. The glyoxalase system is localized in the cytosol and includes two enzymes: the rate limiting enzyme Glo1 and the glyoxalase 2, beside a catalytic amount of reduced glutathione [11]. In diabetic patients, plasma MGO concentration is increased from 2- to 5-fold [12] as a consequence of a higher formation rate but also a reduced detoxification due to the down-regulation of both Glo1 expression and activity [13,14]. We have previously demonstrated that MGO induces endothelial dysfunction in vitro in aortic ECs and in vivo in C57BL/6 mice [[15], [16], [17]]. Other studies have also shown that high levels of MGO contribute to the development of cardiomyopathy by increasing inflammation and EC loss [18], by inducing vascular contractile dysfunction in arterial walls [19] as well as cell death via NF-κB activation in rat diabetic lens [20]. Moreover, emerging evidence has highlighted the harmful effect of MGO on angiogenesis. Indeed, it has been demonstrated that the exposure to MGO impairs viability, migration and tube formation of bovine aortic ECs [21], while the overexpression of Glo1 favours muscle reperfusion after ischemic insults in diabetic rats [22]. However, the molecular mechanisms underlying these effects remain to be elucidated. Hox genes encode for a family of transcription factors highly conserved which act as master regulators of tissue and organ patterning [23]. Moreover, they play an essential role in regulating the function of vascular system. In particular, they coordinate the processes required for proper vascular formation during development, as well as the maintenance and repair of the vasculature system throughout life [24]. Hox gene family includes a number of genes with pro- or anti-angiogenic function. Among the anti-angiogenic Hox genes, it has been shown that HoxA5 blocks angiogenesis and increases vascular stability by the upregulation of anti-angiogenic factors, such as p53, and the downregulation of pro-angiogenic factors, including type 2 vascular endothelial growth factor receptor (VEGFR2) and Hif1alpha [25]. Arderiu G. et al. have shown that HoxA5 expression in ECs stabilizes adherens junctions through β-catenin retention [26], thus preventing the first step of angiogenesis.