Turnaturi, Carlotta Three protective targets in vascular system through the interaction with NO and H2S:GILZ, DHEA and Opa1 protein. [Tesi di dottorato]

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Abstract

Cardiovascular diseases (CVDs) are the most important non-transmissible disease present worldwide. An endothelial dysfunction is often associated to CVD as a possible cause or concomitant cause. Nitric oxide (NO) and hydrogen sulfide (H2S) are two gasotransmitters playing an important role in the control of vascular tone. This thesis aimed to focus on potential protective targets for CVD. In particular, the functional and biochemical exchanges in vasculature were studied. The first one target is Glucocorticoid Induced Leucine Zipper (GILZ) peptide, a widely demonstrated anti-inflammatory molecule, to be used as alternative therapeutic approach of glucocorticoid (GC) treatment, avoiding one of well-known associated vascular side effect, the arterial hypertension. In general GCs treatments are increasingly implicated in the pathogenesis of obesity, metabolic syndrome, arterial hypertension. Thus, there is a need for searching both GCs targeted therapies and additional therapeutic agents/strategies for reducing undesired side effects of chronic GCs treatment. We demonstrated by functional and biochemical study that GILZ-/- mice have a reduction of NO and H2S signaling either in the aorta and plasma. Our evidence suggests that GILZ pathway has also a role in the regulation of vascular tone, supporting the hypothesis that exogenous synthetic GILZ peptide could represent a valid alternative in the replacement of GC. A previous publication demonstrated that the co-administration of dehydroepiandrosterone (DHEA) with dexamethasone resulted in reduction of oxidative stress in kidney-cortex, attenuation of albuminuria and normalization of glutathione redox state, in rabbit. The authors conclude that DHEA might limit several undesirable renal side effects during chronic GC treatment and might be particularly beneficial for the therapy of patients with glucocorticoid induced diabetes. In this regard, in the second part, we focused on the DHEA, a precursor of sex hormone, that decreases with age and seems to have a protective vascular effect. We demonstrate that the relaxant effect of DHEA involves the formation of H2S and NO. We addressed this issue by using mice vessel and cell culture; functional and biochemical assay were performed using CD1 mice and bovine aorta endothelial cells (BAEC). In the last part the involvement of the endothelium as the major responsible of CVD has been addressed with particular attention to the role of a specific protein involved in mitochondria functions. In particular, the third target is the optic atrophy type 1 (Opa1) a key protein that allows the mitochondria fusion. We studied knockout mice where Opa1 has been silenced exclusively in the endothelial cells (EC) (EC-Opa1-/-). In old EC-Opa1-/- mice kidney we observed an increase of oxidative stress and an increase of protein nitrosylation with an augmentation of caveolin expression suggesting un uncoupling of endothelial nitric oxide synthase enzyme (eNOS), the enzyme of synthesis of NO. We also demonstrated that in EC-Opa1-/- old mice there is a reduction of cystathionine-gamma-synthase (CSE) protein expression, one of the main enzymes involved in the bio-synthesis of H2S in vasculature. On the other hand, an increase of inflammatory protein in EC-Opa1-/- kidney and mesenteric artery in adult mice was observed. Thus, Opa1 is important in EC homeostasis and might protect the vascular tree in target organs such as the kidney with a role in aging associated vascular diseases. In conclusion, all the three targets, seems to be associate in a different way to gas transmitters production. In particular we observed a correlative relation with NO and H2S, confirming the key role in cardiovascular disease, underlying, once again, as important are these gasotransmitters in the control of vasculature function.

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