Naftidrofuryl-driven regulation of endothelial ICAM-1 involves nitric oxide

Psychedelics and Anti-inflammatory Activity in Animal Models

The serotonin (5-hydroxytryptamine, 5-HT) 2A receptor is most well known as the common target for classic psychedelic compounds. Interestingly, the 5-HT_2A receptor is the most widely expressed mammalian serotonin receptor and is found in nearly every examined tissue type including neural, endocrine, endothelial, immune, and muscle, suggesting it could be a novel and pharmacological target for several types of disorders. Despite this, the bulk of research on the 5-HT_2A receptor is focused on its role in the central nervous system (CNS). Recently, activation of 5-HT_2A receptors has emerged as a new anti-inflammatory strategy. This review will describe recent findings regarding psychedelics as anti-inflammatory compounds, as well as parse out differences in functional selectivity and immune regulation that exist between a number of well-known hallucinogenic compounds.

Understanding Serotonin 5-HT2A Receptors-regulated cellular and molecular Mechanisms of Chronic Kidney Diseases

Chronic kidney diseases (CKD) are an economic burden and occur worldwide in all age groups, and the advancement of kidney disease at some point leads to deregulate or influence the function of other body organs and to find a specific target to halt the disease progression which is a tedious challenge. Regardless of the underlying mechanisms, it is essential to consider and evaluate the involvement and association of individual endogenous mediators and environmental factors in the progression of CKD to accumulate the required knowledge. More than a dozen pathways leading to relentless progression of CKD have been identified so far, but the association of serotonin 5-HT2A receptor with progressive renal injury is still under process.

Scientific reports demonstrated that the 5-HT2A receptor plays a significant role in renal metabolism, glomerular function, and renal vascular tone. So a better understanding of the evolving role of serotonin 5-HT2A-mediated pathophysiological mechanisms of CKD may be a helpful tool to identify new therapeutic targets. In this review, we will discuss recent interventions, pharmacological target, and the possible implication of serotonin 5-HT2A receptors with associated mechanistic trails leading to CKD.

Psychedelics as anti-inflammatory agents

Serotonin (5-hydroxytryptamine, 5-HT)_2A receptor agonists have recently emerged as promising new treatment options for a variety of disorders. The recent success of these agonists, also known as psychedelics, like psilocybin for the treatment of anxiety, depression, obsessive-compulsive disorder (OCD), and addiction, has ushered in a renaissance in the way these compounds are perceived in the medical community and populace at large. One emerging therapeutic area that holds significant promise is their use as anti-inflammatory agents. Activation of 5-HT_2A receptors produces potent anti-inflammatory effects in animal models of human inflammatory disorders at sub-behavioural levels. This review discusses the role of the 5-HT_2A receptor in the inflammatory response, as well as highlight studies using the 5-HT_2A agonist (R)-2,5-dimethoxy-4-iodoamphetamine [(R)-DOI] to treat inflammation in cellular and animal models. It also examines potential mechanisms by which 5-HT_2A agonists produce their therapeutic effects. Overall, psychedelics regulate inflammatory pathways via novel mechanisms, and may represent a new and exciting treatment strategy for several inflammatory disorders.

The Effects of Serotonin in Immune Cells

Serotonin [5-hydroxytryptamine (5-HT)] plays an important role in many organs as a peripheral hormone. Most of the body’s serotonin is circulating in the bloodstream, transported by blood platelets and is released upon activation. The functions of serotonin are mediated by members of the 7 known mammalian serotonin receptor subtype classes (15 known subtypes), the serotonin transporter (SERT), and by covalent binding of serotonin to different effector proteins. Almost all immune cells express at least one serotonin component. In recent years, a number of immunoregulatory functions have been ascribed to serotonin. In monocytes/macrophages, for example, serotonin modulates cytokine secretion. Serotonin can also suppress the release of tumor necrosis factor-α and interleukin-1β by activating serotonin receptors. Furthermore, neutrophil recruitment and T-cell activation can both be mediated by serotonin. These are only a few of the known immunomodulatory roles of serotonin that we will review here.

Reduction of ICAM-1 expression by carbon monoxide via soluble guanylate cyclase activation accounts for modulation of neutrophil migration

Previously, it was demonstrated that the heme/heme oxygenase (HO)/carbon monoxide (CO) pathway inhibits neutrophil recruitment during the inflammatory response. Herein, we addressed whether the inhibitory effect of the HO pathway on neutrophil adhesion and migration involves the reduction of intracellular adhesion molecule type (ICAM)-1 and beta(2)-integrin expression. Mice pretreated with a specific inhibitor of inducible HO (HO-1), zinc protoporphyrin (ZnPP) IX, exhibit enhanced neutrophil adhesion and migration induced by intraperitoneal injection of Escherichia coli lipopolysaccharide (LPS). These findings are associated with an increase in ICAM-1 expression on mesentery venular endothelium. In accordance, HO-1 inhibition did not enhance LPS-induced neutrophil migration and adhesion in ICAM-1-deficient mice. Furthermore, the treatment with a CO donor (dimanganese decacarbonyl, DMDC) that inhibits adhesion and migration of the neutrophils, reduced LPS-induced ICAM-1 expression. Moreover, neither DMDC nor ZnPP IX treatments changed LPS-induced beta(2)-integrin expression on neutrophils. The effect of CO on ICAM-1 expression seems to be dependent on soluble guanylate cyclase (sGC) activation, since 1H-(1,2,4)oxadiazolo (4,3-a)quinoxalin-1-one (sGC inhibitor) prevented the observed CO effects. Finally, it was observed that the nitric oxide (NO) anti-inflammatory effects on ICAM-1 expression appear to be indirectly mediated by HO-1 activation, since the inhibition of HO-1 prevented the inhibitory effect of the NO donor (S-nitroso-N-acetylpenicillamine) on LPS-induced ICAM-1 expression. Taken together, these results suggest that CO inhibits ICAM-1 expression on endothelium by a mechanism dependent on sGC activation. Thus, our findings identify the HO-1/CO/guanosine 3'5'-cyclic monophosphate pathway as a potential target for the development of novel pharmacotherapy to control neutrophil migration in inflammatory diseases.

Arginase contributes to endothelial cell oxidative stress in response to plasma from women with preeclampsia

AIMS

Preeclampsia is a hypertensive disorder characterized by vascular oxidative stress. Decreased availability of the vasodilator nitric oxide (NO) has been postulated to be involved in the pathophysiology of this disorder. Arginase, an enzyme that competes with nitric oxide synthase (NOS) for l-arginine, not only reduces NO formation but also increases superoxide production by NOS. In placenta of preeclamptic women, arginase upregulation has been shown to be increased and contributes to superoxide formation via uncoupling of NOS. However, the role of arginase in the maternal vasculature is not clear. We hypothesized that arginase would be upregulated in the maternal vasculature of women with preeclampsia and contribute to oxidative stress within the endothelium.

METHODS AND RESULTS

We observed increased arginase expression in the maternal vasculature of women with preeclampsia compared with normotensive pregnant women. Furthermore, human umbilical vein endothelial cells treated with 2% plasma from preeclamptic women show increased arginase II expression and activity that was reduced by a peroxynitrite scavenger. Also, both 3-morpholino sydnonimine and exogenous peroxynitrite increased arginase expression and activity. Preeclamptic plasma treatment increased superoxide and peroxynitrite levels. Superoxide levels were significantly reduced after arginase and NOS inhibition with [(S)-(2-boronoethyl)-l-cysteine] and N(omega)-nitro-l-arginine methyl ester, respectively, but peroxynitrite levels were in fact increased after arginase inhibition. Moreover, in the presence of preeclamptic plasma, l-arginine supplementation increased peroxynitrite formation during arginase inhibition.

CONCLUSION

Increased arginase expression in preeclampsia can induce uncoupling of NOS as a source of superoxide in the maternal vasculature in preeclampsia. However, l-arginine supplementation in the face of oxidative stress could lead to a further increase in peroxynitrite.

Nitric oxide inhibits neutrophil migration by a mechanism dependent on ICAM-1: Role of soluble guanylate cyclase

In the present study, we addressed the role of intercellular adhesion molecule type 1 (ICAM-1/CD54) in neutrophil migration to inflammatory site and whether the inhibitory effect of nitric oxide (NO) upon the neutrophil rolling, adhesion and migration involves down-modulation of ICAM-1 expression through a cyclic GMP (cGMP) dependent mechanism. It was observed that neutrophil migration induced by intraperitoneal administration of endotoxin (LPS), carrageenan (Cg) or N-formyl peptide (fMLP) in ICAM-1 deficient (ICAM-1-/-) is similar to that observed in wild type (WT) mice. The treatment of mice with NO synthase (NOS) inhibitors, NG-nitro-l-arginine, aminoguanidine or with a soluble guanylate cyclase (sGC) inhibitor, ODQ enhanced LPS- or Cg-induced neutrophil migration, rolling and adhesion on venular endothelium. These parameters induced by LPS were also enhanced by 1400 W, a specific iNOS inhibitor, treatment. On the other hand, the treatment of the mice with S-nitroso-N-acetylpenicillamine (SNAP), an NO donor, reduced these parameters induced by LPS or Cg by a mechanism sensitive to ODQ pretreatment. The NOS inhibitors did not enhance LPS-, Cg- or fMLP-induced migration and adhesion in ICAM-1-/- mice. Moreover, genetic (iNOS-/- mice) or pharmacological inhibition of NOS or of sGC enhanced LPS-induced ICAM-1 expression on mesenteric microcirculation vessels of WT mice. By contrast, SNAP reduced the ICAM-1 expression by a mechanism dependent on cGMP. In conclusion, the results suggest that although during inflammation, ICAM-1 does not contribute to neutrophil migration, it is necessary for the down-modulatory effect of inflammation-released NO on the adhesion and transmigration of neutrophils. Moreover, these NO effects are mediated via cGMP.

Gestational diabetes and the adenosine/L-arginine/nitric oxide (ALANO) pathway in human umbilical vein endothelium

Altered endothelial cell function is a key factor associated with vascular disorders and is critical in the fetal growth and development. Pregnancies affected by diseases such as gestational diabetes are associated with human umbilical vein endothelial dysfunction, a finding that has been associated with a high incidence of vascular complications during the adult life. Limited information is available addressing cellular mechanisms associated with altered human umbilical vein endothelial function in gestational diabetes. One of the key signalling pathways associated with altered vascular physiology is the synthesis of the vasodilator nitric oxide (NO) from the cationic amino acid L-arginine by the endothelium (i.e. the endothelial L-arginine/NO pathway). The activity of this signalling pathway is modulated by D-glucose, adenosine, insulin, and ATP, among other molecules, and is upregulated (transcriptional, post-transcriptional and post-translational levels) in gestational diabetes. This review focuses on the cellular and molecular mechanisms involved with elevated adenosine levels in fetal umbilical vein blood and the endothelial L-arginine/NO pathway activity in gestational diabetes. We suggest that a lower capacity of adenosine transport by the fetal endothelium in gestational diabetes leads to extracellular accumulation of this nucleoside and its higher bio-availability activates endothelial P1 type purinoceptors. A functional association between A2a purinoceptor subtype signalling and the activity of the l-arginine transport mediated by human cationic amino acid transporters and endothelial NO synthase activity (i.e. 'ALANO pathway') is proposed, revealing in part the mechanisms that account for human umbilical vein endothelial cell dysfunction programmed through the development of the fetus in gestational diabetes.

Intermittent claudication: an overview

Intermittent claudication (IC) is defined by leg muscle pain, cramping and fatigue brought on by ambulation/exercise; relieved on rest; and caused by inadequate blood supply and is the primary symptom of peripheral arterial disease (PAD). PAD has a detrimental effect on the quality of life. PAD is a debilitating atherosclerotic disease of the lower limbs and is associated with an increased risk of cardiovascular morbidity and mortality. IC is an extremely important marker of atheroma. Up to 60% patients with IC have significant underlying coronary and/or carotid disease and 40% of all patients suffering from IC die or suffer a stroke within 5 years of presentation. The therapeutic intervention of IC essentially aims at providing symptomatic relief and reducing the systemic cardiovascular complications. Although exercise therapy is one of the most efficacious conservative treatments for claudication, the pharmacotherapeutic goals can be best achieved through an increase in the walking capacity to improve quality of life and a decrease in rates of amputation. In the development of treatment for IC, an aggressive non-pharmacological intervention and pharmacological treatment of the risk factors associated with IC are considered. In the next 2 years, the results of major trials of drugs that stabilize and regress atherosclerosis such as statins and angiotensin converting enzyme inhibitors, and anti-platelet agents, recombinant growth factors and immune modulators will be available for IC. Levocarnitine (l-carnitine) and a derivative, propionyl levocarnitine, are emerging agents that increase the pain-free walking and improve the quality of life in IC patients by working at the metabolism and exercise performance of ischemic muscles. This article provides a comprehensive review of the pathophysiology involved, diagnosis of IC and existing and emerging pharmacotherapies with rationale for their use in its treatment.

Controlled release of a nitric oxide donor for the prevention of delayed cerebral vasospasm following experimental subarachnoid hemorrhage in nonhuman primates

OBJECT

Results of prior studies in rats and rabbits show that the alteration of vasomotor tone in vasospasm following periadventitial blood exposure may be reversed, at least in part, by the administration of compounds releasing nitric oxide (NO). The authors have now generalized this finding to nonhuman primates.

METHODS

Ten cynomolgus monkeys underwent cerebral angiography before and 7 days following the induction of subarachnoid hemorrhage (SAH) by the placement of 2 to 3 ml clotted autologous blood around the supraclinoid carotid, proximal anterior cerebral, and proximal middle cerebral arteries. An ethylene vinyl acetate copolymer, either blank (five animals) or containing 20% w/w (Z)-1-[2-(2-aminoethyl)-N-(2-aminoethyl)amino]diazen-1-ium-1,2-diolate (DETA/NO, 4.3 mg/kg; five animals) was placed adjacent to the vessels at the time of surgery. Animals were killed on Day 7 post-SAH following repeated cerebral angiography. The mean percentage of control vascular areal fraction was calculated from angiograms. Cerebral vessels were sectioned and the mean percentage of lumen patency was calculated. One animal that had received the DETA/NO polymer died prior to repeated angiography. In the remaining animals, DETA/NO caused a significant decrease in vasospasm compared with controls, according to both angiographic (84.8 +/- 8.6 compared with 56.6 +/- 5.2%, respectively, p < 0.05) and histological studies (internal carotid artery 99.3 +/- 1.8 compared with 60.1 +/- 4.4%, respectively, p < 0.001; middle cerebral artery 98.4 +/- 3 compared with 56.1 +/- 3.7%, respectively, p < 0.001; and anterior cerebral artery 89.2 +/- 8.5 compared with 55.8 +/- 6.3%, respectively, p < 0.05).

CONCLUSIONS

The controlled release of DETA/NO is effective in preventing delayed cerebral vasospasm in an SAH model in nonhuman primates. The death of one animal in the treatment group indicates that the present dosage is at the threshold between therapeutic efficacy and toxicity.

[Pain management in non-juvenile, aseptic osteonecrosis]

BACKGROUND

Adult aseptic osteonecrosis (ON) represents a clinical picture with unexplained etiology. Since curative treatment of this disease often succeeds only in the early stage, pain therapy plays an important role in the treatment process.

METHOD

We compared established and novel treatment options for ON as well as our own results after i.v. administration of the prostacyclin analogue iloprost with corresponding studies in the literature.

RESULTS

In addition to treatment with nonsteroidal antirheumatic agents and opioids, surgical "core decompression," vasoactive medications, and hyperbaric oxygenation are effective. Treatment with iloprost for 5 days resulted in highly significant pain reduction.

CONCLUSION

Symptomatic treatment is indicated in all stages of ON and curative treatment in stage I and early stage II. In cases of disease progression in the large joints, early endoprosthetic replacement is indicated to avoid secondary damage. In addition to employing vasoactive substances, a further curative treatment approach could be the use of mesenchymal stem cells.

Aging and the endothelium

One link between aging and endothelial function is the inflammatory response. On one hand, the latter shortens the biological engaged by activated leukocytes against invaders or stressing agents. On the other hand, the surveyed tissues become targets of the toxicity of reactive oxygen species, ROS. The ensuing regeneration is source of transcriptional infidelity, leading to the alteration of the repaired tissue. Hence, the toll of inflammatory stress consists in premature senescence of cell and tissues. This hypothesis is discussed in the present review, which focuses on the molecular targets relevant for cancer and degenerative diseases, both tributary to an inflammatory environment and taking advantage from the consequences of cell and tissue dysfunctions characteristic of aging. Eventually, adaptation to stress, whatever its origin -inflammatory and/or psychosocial-is discussed. Basal nitric oxide (NO) release, such as provided through moderate exercise, seems to be the most potent guardian against immune, nervous and cardiovascular over-stimulation. Tissue regeneration is also obtained by circulating endothelial progenitors able to recognize the damaged tissue. To avoid post-inflammatory alterations resulting in detrimental changes of tissues and organs, the pharmacological protection of endothelium by agents able to modulate its activation seems crucial to us.