Arterial Remodelling in Chronic Kidney Disease: Impact of Uraemic Toxins and New Pharmacological Approaches.

Chronic kidney disease (CKD) is a major public health concern that affects around 10 percent of the world's population. The severity of CKD is mainly due to the high prevalence of cardiovascular (CV) complications in this population. The aim of this review is to describe the arterial remodelling associated with CKD, to provide a quick overview of the mechanisms involved and to review the recent pharmacological approaches aimed at improving vascular health in CKD. CKD patients are exposed to metabolic and haemodynamic disorders that may affect the CV system. Large artery functional and geometric abnormalities have been well documented in CKD patients and are associated with an increase in arterial stiffness and a maladaptive remodelling. Uraemic toxins, such as indoxyl sulphate, p-cresyl sulphate, protein carbamylation and advanced glycation products, exert various effects on vascular smooth muscle cell functions. The low-grade inflammation associated with CKD may also affect arterial wall composition and remodelling. It is worth noting that the CV risk for CKD patients remains high despite the pharmacological control of traditional CV risk factors, suggesting the need for innovative therapeutic strategies. An interventional study targeting the NLRP3 inflammasome has provided some interesting preliminary results that need to be confirmed, especially in terms of safety.

Effects of physical activity on cell-to-cell communication during type 2 diabetes: A focus on miRNA signaling.

Type 2 diabetes (TD2) is a progressive disease characterized by hyperglycemia that results from alteration in insulin secretion, insulin resistance, or both. A number of alterations involving different tissues and organs have been reported to the development and the progression of T2D, and more relevantly, through cell-to-cell communication pathways. Recent studies demonstrated that miRNAs are considerably implicated to cell-to-cell communication during T2D. Physical activity (PA) is associated with decreasing risks of developing T2D and acts as insulin-like factor. Cumulative evidence suggests that this effect could be mediated in part through improving insulin sensitivity in T2D and obese patients and modulating miRNAs synthesis and release in healthy patients. Therefore, the practice of PA should ideally be established before the initiation of T2D. This review describes cell-to-cell communications involved in the pathophysiology of T2D during PA.

Decreased vasorelaxation induced by iloprost during acute inflammation in human internal mammary artery.

Cyclooxygenase-2 (COX-2) induction in human internal mammary arteries (IMA) under inflammatory conditions has been associated with attenuated norepinephrine (NE)-induced vasoconstriction. This effect was associated with increased prostaglandin (PG) E2 and prostacyclin (PGI2) releases. The present study was designed to assess the role of these PG and their receptors (EP and IP, respectively) on the vascular reactivity during acute inflammation. Isolated IMA were cultured in the absence (Control conditions) or presence (Inflammatory conditions) of both interleukin-1 beta (IL-1ß) and lipopolysaccharide (LPS). The vasorelaxation and the increased content of cyclic adenosine monophosphate (cAMP) induced by iloprost, a PGI2 analogue, were significantly reduced under inflammatory conditions and restored in preparations cultured with the IP antagonist (CAY10441). Decreased cAMP levels under inflammatory conditions are due to at least increased phosphodiesterase (PDE) 4B expression. On the other hand, PGE2, thromboxane analogues and EP agonists-induced vasoconstrictions were not affected under inflammatory conditions. No vasorelaxation was observed with PGD2, PGE2 or the EP2/4 agonists in pre-contracted IMA. Finally, using RT-qPCR and immunohistochemistry, the COX-2, IP receptor and PGI2 synthase (PGIS) were detected. A significant increase of COX-2 and moderate increase of IP mRNA expression was observed under inflammatory conditions, whereas PGIS mRNA level was not affected. This study demonstrates that PGI2/IP receptor signalling and PGI2-induced relaxation are impaired in human IMA during acute inflammation, whereas the responses induced by other prostanoids are not affected. These results could explain some of the mechanisms of vascular dysfunction reported in inflammatory conditions.

Asthma causes inflammation of human pulmonary arteries and decreases vasodilatation induced by prostaglandin I2 analogs.

OBJECTIVE: Asthma is a chronic inflammatory disease associated with increased cardiovascular events. This study assesses the presence of inflammation and the vascular reactivity of pulmonary arteries in patients with acute asthma. METHODS: Rings of human pulmonary arteries obtained from non-asthmatic and asthmatic patients were set up in organ bath for vascular tone monitoring. Reactivity was induced by vasoconstrictor and vasodilator agents. Protein expression of inflammatory markers was detected by western blot. Prostanoid releases and cyclic adenosine monophosphate (cAMP) levels were quantified using specific enzymatic kits. RESULTS: Protein expression of cluster of differentiation 68, intercellular adhesion molecule-1, vascular cell adhesion molecule-1, and cyclooxygenase-2 was significantly increased in arteries obtained from asthmatic patients. These effects were accompanied by an alteration of vasodilatation induced by iloprost and treprostinil, a decrease in cAMP levels and an increase in prostaglandin (PG) E2 and PGI2 synthesis. The use of forskolin (50 µmol/L) has restored the vasodilatation and cAMP release. No difference was observed between the two groups in reactivity induced by norepinephrine, angiotensin II, PGE2, KCl, sodium nitroprusside, and acetylcholine. CONCLUSION: Acute asthma causes inflammation of pulmonary arteries and decreases vasodilation induced by PGI2 analogs through the impairment of cAMP pathway.

Prostaglandin E2 receptor subtypes in human blood and vascular cells.

Prostaglandin E(2) is produced in inflammatory responses via the cyclooxygenase pathway and regulates a variety of physiological and pathological reactions through four different receptor subtypes; EP(1), EP(2), EP(3) and EP(4). The role of the classical prostanoid receptors stimulated by prostaglandin I(2) and thromboxane A(2) in the blood circulation has been largely studied, whereas the other receptors such as EP activated by prostaglandin E(2), have been recently shown to be also implicated. There is now increasing evidence suggesting an important role of EP(3) and EP(4) receptor subtypes in the control of the human vascular tone and remodeling of the vascular wall as well in platelet aggregation and thrombosis. These receptors are implicated in vascular homeostasis and in the development of some pathological situations, such as atherosclerosis, aneurysms and hypertension. The use of specific EP agonists/antagonists would provide a novel cardiovascular therapeutic approach. In this review, we discuss the role of prostaglandin E(2) receptors in the control of human blood and vascular cells.

Prostaglandin E2 induced contraction of human intercostal arteries is mediated by the EP3 receptor.

Arterial vascularization of the spinal cord may be mechanically or functionally altered during thoraco-abdominal surgery/intravascular procedures. Increased arterial pressure has been shown to restore spinal perfusion and function probably by increasing the blood flow through the intercostal arteries. The regulation of human intercostal artery (HICA) vascular tone is not well documented. Prostaglandin (PG)E(2) concentration is increased during inflammatory conditions and has been shown to regulate vascular tone in many preparations. In this context, the pharmacological response of HICA to PGE(2) and the characterization of the PGE(2) receptor subtypes (EP(1), EP(2), EP(3) or EP(4)) involved are of importance and that is the aim of this study. Rings of HICA were prepared from 29 patients and suspended in organ baths for isometric recording of tension. Cumulative concentration-response curves were performed in these preparations with various EP receptor agonists in the absence or presence of different receptor antagonists or inhibitors. PGE(2) induced the contraction of HICA (E(max)=7.28 ± 0.16 g; pEC(50) value=0.79 ± 0.18; n=17); contractions were also observed with the EP(3) receptor agonists, sulprostone, 17-phenyl-PGE(2), misoprostol or ONO-AE-248. In conclusion, PGE(2) induced vasoconstriction of HICA via EP(3) receptor subtypes and this result was confirmed by the use of selective EP receptor antagonists (L-826266, ONO-8713, SC-51322) and by a strong detection of EP(3) mRNA. These observations suggest that in the context of perioperative inflammation, increased PGE(2) concentrations could trigger vasoconstriction of HICA and possibly alter spinal vascularization.

Involvement of prostaglandin F2α in preeclamptic human umbilical vein vasospasm: a role of prostaglandin F and thromboxane A2 receptors.

OBJECTIVE: Preeclampsia is characterized by hypertension and proteinuria developing after 20 weeks of gestation. Increased vasoconstriction can be one of the major underlying pathophysiological event in this syndrome. We examined the role of vasoconstrictor prostanoid, prostaglandin F2α (PGF2α) in preeclamptic and normotensive human umbilical veins. METHODS: Umbilical veins were set up in organ bath. The concentration-response curves of PGF2α (endogenous agonist of prostaglandin F receptor) and fluprostenol (prostaglandin F receptor selective agonist) were determined in normal and preeclamptic veins either in the absence or presence of BAY u3405 (thromboxane A2 receptor selective antagonist). PGF2α and its major metabolite concentrations were measured by enzyme immunoassay kit. The expression of vasoconstrictor prostanoid receptors was determined by western blot. RESULTS: The concentration-dependent contractions to PGF2α and fluprostenol were significantly increased in umbilical vein preparations derived from preeclamptic women compared with those of normotensives. Increased reactivity was related with enhanced sensitivity to these spasmogens in preeclamptic veins. BAY u3405 (10 µmol/l) did not modify the responsiveness to PGF2α in normal umbilical veins whereas moderately reduced the contractions in preeclamptic preparations. Serum concentrations of PGF2α and its major metabolite, 13,14-dihydro-15-keto-PGF2α, were comparable between preeclamptics and normotensives whereas the metabolite concentration was elevated in umbilical cord serum of preeclamptics. 13,14-dihydro-15-keto-PGF2α, release was also increased in umbilical vein preparations of preeclamptic women. An increased prostaglandin F receptor protein expression was determined whereas EP3 and thromboxane A2 protein expressions were unchanged in preeclamptic umbilical veins. CONCLUSION: Prostaglandin F and thromboxane A2 receptors activation by PGF2α could be involved in umbilical vasospasm observed in preeclampsia.

Altered reactivity to norepinephrine through COX-2 induction by vascular injury in hypercholesterolemic rabbits.

Although long-term use of cyclooxygenase (COX)-2 inhibitors may be associated with increased cardiovascular risk, their effects on vascular reactivity in atherosclerosis has remained largely unexplored. The aim of the present study was to evaluate the role of COX-2 induced by an atherosclerotic process, in the local control of vascular tone. New Zealand White rabbits were fed 0.3% cholesterol and subjected to balloon injury of the abdominal aorta. After 2 wk, the aorta was removed and used for organ bath experiments and immunohistochemistry, and the prostaglandins released were measured using enzyme immunoassays. Hypercholesterolemia and vascular injury significantly increased the thickness of the intimal layer, which was associated with an induction of COX-2 immunoreactivity throughout the aortic wall. In these preparations, a significant decrease of the maximal contractions induced by norepinephrine was observed. The norepinephrine-induced contractions of atherosclerotic preparations were restored by the COX inhibitors DuP-697 (0.5 micromol/l) and indomethacin (1.7 micromol/l), to similar contractions as was observed in aortic preparations derived from healthy rabbits. Norepinephrine stimulation of the abdominal aorta was accompanied by increased levels of prostaglandin I(2) but not of prostaglandin E(2), prostaglandin D(2), or thromboxane A(2) in atherosclerotic compared with normal aorta. Selective COX-2 inhibition significantly decreased the prostaglandin I(2) release from atherosclerotic aorta but had no effect on the prostaglandin release from aortic preparations derived from normal rabbits. These observations suggest that the local induction of COX-2 during atherosclerosis decreased the sensitivity to norepinephrine and that COX-2 inhibitors may increase vascular reactivity at sites of atherosclerotic lesions.

Selective cyclooxygenase-2 inhibition directly increases human vascular reactivity to norepinephrine during acute inflammation.

AIMS: The use of cyclooxygenase-2 (COX-2) inhibitors has been reported to be associated with detrimental vascular events. The aim of our study was to evaluate the role of COX-2 activity in the control of human vascular tone under inflammatory conditions. METHODS AND RESULTS: Using organ bath experiments, the contraction induced by norepinephrine (NE), U46619, acetylcholine, and KCl was performed on isolated human internal mammary arteries (IMA) cultured in the presence or absence of both interleukin-1beta (IL-1beta) and lipopolysaccharide (LPS) with or without endothelium. Under these conditions the COX (cyclooxygenase) isoforms were detected by immunohistochemistry and western blot, and the prostaglandins (PG) and thromboxane (Tx) released were measured using an enzyme immunoassay kit. A significant decrease in the maximal effect induced by NE but not by other stimuli was observed in the IL-1beta- and LPS-treated preparations after 6 and 24 h of culture (-19 +/- 6 and -25 +/- 4%, respectively), an effect that was endothelium independent. Under this inflammatory condition, the COX-2 inhibitors DFU (1 micromol/L), DuP-697 (0.5 micromol/L), and Etoricoxib (1 micromol/L) markedly restored and increased the vascular reactivity to NE. These alterations were not observed with SC-560 (1 micromol/L), a selective COX-1 inhibitor. In addition, the COX-1 isoform was always detected and the COX-2 isoform was only found in human IMA exposed for 6 or 24 h under inflammatory conditions. The COX-2 induction was accompanied by an increase in PGE(2) (prostaglandin E(2)) and PGI(2) (prostaglandin I(2)) release in the culture medium (approximately 2.5-fold) but not with an increase in TxA(2) (thromboxane A(2)) release. CONCLUSION: These observations suggest that the inhibition of COX-2 directly potentiates the human vascular tone induced by NE under inflammatory conditions.

Increased insulin-stimulated expression of arterial angiotensinogen and angiotensin type 1 receptor in patients with type 2 diabetes mellitus and atheroma.

OBJECTIVE: Because inhibition of the renin-angiotensin system (RAS) reduces the onset of type 2 diabetes (T2D) and prevents atherosclerosis, we investigated the expression of RAS in the arterial wall of T2D and nondiabetic (CTR) patients. METHODS AND RESULTS: mRNA and protein levels of angiotensinogen (AGT), angiotensin-converting enzyme (ACE) and AT1 receptor (AT1R) were determined in carotid atheroma plaque, nearby macroscopically intact tissue (MIT), and in vascular smooth muscle cells (VSMCs) before and after insulin stimulation from 21 T2D and 22 CTR patients. AGT and ACE mRNA and their protein levels were 2- to 3-fold higher in atheroma and in MIT of T2D patients. VSMCs from T2D patients had respectively 2.5- and 5-fold higher AGT and AT1R mRNA and protein contents. Insulin induced an increase in AGT and AT1R mRNA with similar ED50. These responses were blocked by PD98059, an inhibitor of MAP-kinase in the two groups whereas wortmannin, an inhibitor of PI3-kinase, partially prevented the response in CTR patients. Phosphorylated ERK1-2 was 4-fold higher in MIT from T2D than from CTR patients. CONCLUSIONS: The arterial RAS is upregulated in T2D patients, which can be partly explained by an hyperactivation of the ERK1-2 pathway by insulin.