Vascular effects of linagliptin in non-obese diabetic mice are glucose-independent and involve positive modulation of the endothelial nitric oxide synthase (eNOS)/caveolin-1 (CAV-1) pathway

Aim: To test the effect of linagliptin in non-obese diabetic (NOD) mice, a murine model of type 1 diabetes, to unveil a possible direct cardiovascular action of dipeptidyl peptidase 4 (DPP-4) inhibitors beyond glycaemia control. Methods: NOD mice were grouped according to glycosuria levels as NODI: none; NODII: high; NODIII: severe. Linagliptin treatment was initiated once they reached NODII levels. Vascular reactivity was assessed ex vivo on aorta harvested from mice upon reaching NODIII level. In a separate set of experiments, the effect of linagliptin was tested directly in vitro on vessels harvested from untreated NODIII, glucagon-like peptide-1 (GLP-1) receptor knockout and soluble guanylyl cyclase-α1 knockout mice. Molecular and cellular studies were performed on endothelial and endothelial nitric oxide synthase (eNOS)-transfected cells. Results: In this ex vivo vascular study, endothelium-dependent vasorelaxation was ameliorated and eNOS/nitric oxide (NO)/soluble guanylyl cyclase (sGC) signalling was enhanced. In the in vitro vascular study, linagliptin exerted a direct vasodilating activity on vessels harvested from both normo- or hyperglycaemic mice. The effect was independent from GLP-1/GLP-1 receptor (GLP-1R) interaction and required eNOS/NO/sGC pathway activation. Molecular studies performed on endothelial cells show that linagliptin rescues eNOS from caveolin-1 (CAV-1)-binding in a calcium-independent manner. Conclusion: Linagliptin, by interfering with the protein-protein interaction CAV-1/eNOS, led to an increased eNOS availability, thus enhancing NO production. This mechanism accounts for the vascular effect of linagliptin that is independent from glucose control and GLP-1/GLP-1R interaction

Urothelium muscarinic activation phosphorylates CBS Ser227 via cGMP/PKG pathway causing human bladder relaxation through H 2 S production

The urothelium modulates detrusor activity through releasing factors whose nature has not been clearly defined. Here we have investigated the involvement of H2S as possible mediator released downstream following muscarinic (M) activation, by using human bladder and urothelial T24 cell line. Carbachol stimulation enhances H2S production and in turn cGMP in human urothelium or in T24 cells. This effect is reversed by cysthationine-β-synthase (CBS) inhibition. The blockade of M1 and M3 receptors reverses the increase in H2S production in human urothelium. In T24 cells, the blockade of M1 receptor significantly reduces carbachol-induced H2S production. In the functional studies, the urothelium removal from human bladder strips leads to an increase in carbachol-induced contraction that is mimicked by CBS inhibition. Instead, the CSE blockade does not significantly affect carbachol-induced contraction. The increase in H2S production and in turn of cGMP is driven by CBS-cGMP/PKG-dependent phosphorylation at Ser(227) following carbachol stimulation. The finding of the presence of this crosstalk between the cGMP/PKG and H2S pathway downstream to the M1/M3 receptor in the human urothelium further implies a key role for H2S in bladder physiopathology. Thus, the modulation of the H2S pathway can represent a feasible therapeutic target to develop drugs for bladder disorders

Human Cystathionine-β-Synthase Phosphorylation on Serine227 Modulates Hydrogen Sulfide Production in Human Urothelium

Urothelium, the epithelial lining the inner surface of human bladder, plays a key role in bladder physiology and pathology. It responds to chemical, mechanical and thermal stimuli by releasing several factors and mediators. Recently it has been shown that hydrogen sulfide contributes to human bladder homeostasis. Hydrogen sulfide is mainly produced in human bladder by the action of cystathionine-β-synthase. Here, we demonstrate that human cystathionine-β-synthase activity is regulated in a cGMP/PKG-dependent manner through phosphorylation at serine 227. Incubation of human urothelium or T24 cell line with 8-Bromo-cyclic-guanosine monophosphate (8-Br-cGMP) but not dibutyryl-cyclic-adenosine monophosphate (d-cAMP) causes an increase in hydrogen sulfide production. This result is congruous with the finding that PKG is robustly expressed but PKA only weakly present in human urothelium as well as in T24 cells. The cGMP/PKG-dependent phosphorylation elicited by 8-Br-cGMP is selectively reverted by KT5823, a specific PKG inhibitor. Moreover, the silencing of cystathionine-β-synthase in T24 cells leads to a marked decrease in hydrogen sulfide production either in basal condition or following 8-Br-cGMP challenge. In order to identify the phosphorylation site, recombinant mutant proteins of cystathionine-β-synthase in which Ser32, Ser227 or Ser525 was mutated in Ala were generated. The Ser227Ala mutant cystathionine-β-synthase shows a notable reduction in basal biosynthesis of hydrogen sulfide becoming unresponsive to the 8-Br-cGMP challenge. A specific antibody that recognizes the phosphorylated form of cystathionine-β-synthase has been produced and validated by using T24 cells and human urothelium. In conclusion, human cystathionine-β-synthase can be phosphorylated in a PKG-dependent manner at Ser227 leading to an increased catalytic activity

Interleukin-17 (IL-17) triggers systemic inflammation, peripheral vascular dysfunction, and related prothrombotic state in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is one of the most prevalent forms of neurodegenerative disorders. Previously, we have shown that in vivo administration of an IL-17 neutralizing antibody (IL-17Ab) rescues amyloid-β-induced neuro-inflammation and memory impairment, demonstrating the pivotal role of IL-17 in AD-derived cognitive deficit. Recently, AD has been recognized as a more intriguing pathology affecting vascular networks and platelet function. However, not much is known about peripheral vascular inflammation and how pro-inflammatory circulating cells/mediators could affect peripheral vessels' function. This study aimed to evaluate whether IL-17Ab treatment could also impact peripheral AD features, such as systemic inflammation, peripheral vascular dysfunction, and related pro-thrombotic state in a non-genetic mouse model of AD. Mice were injected intracerebroventricularly with Aβ1-42 peptide (3 μg/3 μl). To evaluate the systemic/peripheral protective profile of IL-17Ab, we used an intranasal administration of IL-17Ab (1 μg/10 μl) at 5, 12, and 19 days after Aβ1-42 injection. Circulating Th17/Treg cells and related cyto-chemokines, haematological parameters, vascular/endothelial reactivity, platelets and coagulation function in mice were evaluated. IL-17Ab treatment ameliorates the systemic/peripheral inflammation, immunological perturbance, vascular/endothelial impairment and pro-thrombotic state, suggesting a key role for this cytokine in fostering inflammatory processes that characterize the multifaced aspects of AD. </p

A new original nutraceutical formulation ameliorates the effect of Tadalafil on clinical score and cGMP accumulation.

Objective: To assess the efficacy of the combination of Tadalafil 5 mg and nutritional supplements composed by Panax ginseng, Moringa Oleifera and Rutin on erectile function in men with mild and moderate vasculogenic ED.Methods: we prospectively enrolled 86 patients divided into two groups A (45), B (33) in this multicenter randomized, doubleblind, placebo-controlled trial . Drop out was 8 patients (3 patients in group A and 5 in Group B). At screening visit patients underwent clinical examination, blood test (hormonal and metabolic profile) and filled out the IIEF-5 questionnaire and the SEP-2, SEP-3. Patients were randomized by a computergenerated list to receive either Tadalafil 5 mg once daily plus nutritional supplement once daily (group A) or Tadalafil 5 mg plus placebo with the same administration schedule (group B) for 3 months. Blood samples, IIEF-5, SEP-2 and SEP-3 have been collected again after 3 months. cGMP was measured in platelets of 38 patients at baseline and after one months. Results: Mean age was 59.98 ± 6.90 (range 38-69), mean IIEF-5 score at baseline was 13.59 ± 3.90. After three months of treatment, IIEF-5 score significantly improved in both groups compared to baseline (13.18 ± 3.75 vs 20.48 ± 2.24, p < 0.0001; 14.15 ± 4.09 vs 19.06 ± 4.36, p < 0.0001, in group A and group B respectively). Patients treated with Tadalafil plus nutritional supplement showed a significantly higher increase in IIEF-5 score compared to those who received placebo (7.27 ± 2.20 and 4.9 ± 2.79, respectively; p < 0.0001;). No hormonal differences and metabolic effects were found. According cGMP result, nutritional supplements ameliorates and extends the activity of the chronic treatment. Conclusions: IIEF-5 significant increase in group B, can be ascribed to the nutritional supplement properties and antioxidant effects of moringa oleifera, ginseng and rutin and this can enhance the endothelial NO and cGMP production

Endogenous Urotensin II Selectively Modulates Erectile Function through eNOS

Urotensin II (U-II) is a cyclic peptide originally isolated from the neurosecretory system of the teleost fish and subsequently found in other species, including man. U-II was identified as the natural ligand of a G-protein coupled receptor, namely UT receptor. U-II and UT receptor are expressed in a variety of peripheral organs and especially in cardiovascular tissue. Recent evidence indicates the involvement of U-II/UT pathway in penile function in human, but the molecular mechanism is still unclear. On these bases the aim of this study is to investigate the mechanism(s) of U-II-induced relaxation in human corpus cavernosum and its relationship with L-arginine/Nitric oxide (NO) pathway.Human corpus cavernosum tissue was obtained following in male-to-female transsexuals undergoing surgical procedure for sex reassignment. Quantitative RT-PCR clearly demonstrated the U-II expression in human corpus cavernosum. U-II (0.1 nM-10 µM) challenge in human corpus cavernosum induced a significant increase in NO production as revealed by fluorometric analysis. NO generation was coupled to a marked increase in the ratio eNOS phosphorilated/eNOS as determined by western blot analysis. A functional study in human corpus cavernosum strips was performed to asses eNOS involvement in U-II-induced relaxation by using a pharmacological modulation. Pre-treatment with both wortmannin or geldanamycinin (inhibitors of eNOS phosphorylation and heath shock protein 90 recruitment, respectively) significantly reduced U-II-induced relaxation (0.1 nM-10 µM) in human corpus cavernosum strips. Finally, a co-immunoprecipitation study demonstrated that UT receptor and eNOS co-immunoprecipitate following U-II challenge of human corpus cavernosum tissue.U-II is endogenously synthesized and locally released in human corpus cavernosum. U-II elicited penile erection through eNOS activation. Thus, U-II/UT pathway may represent a novel therapeutical target in erectile dysfunction

New pharmacological prospectives in erectile function

Abstract Erectile dysfunction (ED), defined as the consistent or recurrent inability of a man to attain and/or maintain a penile erection sufficient for sexual activity ), can be caused by a number of different pathophysiological process. For these reasons, the present study can be divided into three steps in which we have analyzed various aspects of physiology and physiopathology of erectile function to give a contribution in the development of novel therapeutic approaches for treatment of ED and sexual arousal disorders. We have first analyzed man dysfunctions that develop into ED, and in particular Peyroeni’s disease (PD), a connective tissue disorder involving the growth of fibrous plaques in the tunica albuginea of the penis. PD consists in a molecular and physiopathological disorder that is poorly understood mainly because of to the lack of an appropriate animal model. We were looking for a spontaneous animal model that may mirror the natural history of human PD and we showed that tight skin mice (Tsk) could reproduce the natural development of human PD with age. Indeed in Tsk mice was observed: i) a gradual increase in synthesis and deposition of collagen of type I, ii) an high level of TGFβ especially in the earlier stage of the disease, iii) an increase of iNOS mRNA level during the development of the pathology. PD represent a particular case of ED. Indeed, it is now widely accepted that ED is predominantly a vascular disease. In particular the erectile function is regulated by a balance between vasorelaxant and vasoconstrictor factors. The breaking of this balance can be cause of ED. To identify new pathways involved in penile erection, that could be target for new therapies, our attention has been placed on urotensin II (UII), an endogenous peptide previously described as an important vasoactive peptide. Interestingly, our data suggest that i) UII receptor is expressed in rat corpus cavernosum and in anesthetized rats, intracavernous administration of UII causes an increase of intracavernous pressure; ii) UII receptor is expressed on HCC and it is localized on endothelial cell; iii) the receptor is functional and mediates an endothelium-dependent relaxation that involves the L-arginine/NO pathway.; iiii) UII effect was inhibited by both geldanamicin and wortmannin. Finally we have analyzed various methods for ED diagnosis. ED and its grade and the efficacy of ED treatment, are actually evaluated by medical questionnaire scores, a non-objective method. The most used therapy in ED treatment is actually represented by PDE5 inhibitors which, inhibiting PDE5, increase the action of cGMP and thereby enhance penile cavernosum and vascular smooth muscle relaxation and erection. The target of these drugs, PDE5, has been founded in other tissues than the penis, such as vascular smooth muscle, smooth muscle of the gastrointestinal tract and in platelets. For these reasons we have assessed if platelet cGMP could act as a biomarker of PDE5 activity in ED clinical studies. In conclusion at first we have showed that: i) the Tsk mouse, as it replicates similar condition to the human disease, may represents a new animal model of PD naturally occurring; ii) UII could represent a novel target in physiology and physiopathology of penile erection; iii) Platelet cGMP is a relative simple assay and can provide information on the activity and duration of PDE5 inhibition within and over plasma levels

Linagliptin Rescues Vascular Response in Nonobese Diabetic Mice: Involvement of the L-arginine/eNOS Pathway

Chiarimento dei meccanismi molecolari alla base dell'effetto antidiabetico del Linagliptin