Comparison of plasma serotonin levels in patients with variant angina pectoris versus healed myocardial infarction

Role of Vasoactive Hormone-Induced Signal Transduction in Cardiac Hypertrophy and Heart Failure

Heart failure is the common concluding pathway for a majority of cardiovascular diseases and is associated with cardiac dysfunction. Since heart failure is invariably preceded by adaptive or maladaptive cardiac hypertrophy, several biochemical mechanisms have been proposed to explain the development of cardiac hypertrophy and progression to heart failure. One of these includes the activation of different neuroendocrine systems for elevating the circulating levels of different vasoactive hormones such as catecholamines, angiotensin II, vasopressin, serotonin and endothelins. All these hormones are released in the circulation and stimulate different signal transduction systems by acting on their respective receptors on the cell membrane to promote protein synthesis in cardiomyocytes and induce cardiac hypertrophy. The elevated levels of these vasoactive hormones induce hemodynamic overload, increase ventricular wall tension, increase protein synthesis and the occurrence of cardiac remodeling. In addition, there occurs an increase in proinflammatory cytokines and collagen synthesis for the induction of myocardial fibrosis and the transition of adaptive to maladaptive hypertrophy. The prolonged exposure of the hypertrophied heart to these vasoactive hormones has been reported to result in the oxidation of catecholamines and serotonin via monoamine oxidase as well as the activation of NADPH oxidase via angiotensin II and endothelins to promote oxidative stress. The development of oxidative stress produces subcellular defects, Ca2+-handling abnormalities, mitochondrial Ca2+-overload and cardiac dysfunction by activating different proteases and depressing cardiac gene expression, in addition to destabilizing the extracellular matrix upon activating some metalloproteinases. These observations support the view that elevated levels of various vasoactive hormones, by producing hemodynamic overload and activating their respective receptor-mediated signal transduction mechanisms, induce cardiac hypertrophy. Furthermore, the occurrence of oxidative stress due to the prolonged exposure of the hypertrophied heart to these hormones plays a critical role in the progression of heart failure.

Advances and Challenges in Biomarkers Use for Coronary Microvascular Dysfunction: From Bench to Clinical Practice

Coronary microvascular dysfunction (CMD) is related to a broad variety of clinical scenarios in which cardiac microvasculature is morphologically and functionally affected, and it is associated with impaired responses to vasoactive stimuli. Although the prevalence of CMD involves about half of all patients with chronic coronary syndromes and more than 20% of those with acute coronary syndrome, the diagnosis of CMD is often missed, leading to the underestimation of its clinical importance. The established and validated techniques for the measurement of coronary microvascular function are invasive and expensive. An ideal method to assess endothelial dysfunction should be accurate, non-invasive, cost-effective and accessible. There are varieties of biomarkers available, potentially involved in microvascular disease, but none have been extensively validated in this heterogeneous clinical population. The investigation of potential biomarkers linked to microvascular dysfunction might improve the assessment of the diagnosis, risk stratification, disease progression and therapy response. This review article offers an update about traditional and novel potential biomarkers linked to CMD.

Effects of M-1, a Major Metabolite of Sarpogrelate, on 5-HT-Induced Constriction of Isolated Human Internal Thoracic Artery

Sarpogrelate, a selective 5-hydroxytryptamine (5-HT)_2A receptor antagonist, inhibits 5-HT-induced platelet aggregation and vasoconstriction. It improves ischemic symptoms in patients with arteriosclerosis obliterans. M-1 is a major metabolite of sarpogrelate, and has been reported to show a higher affinity for the 5-HT_2A receptor on platelets than sarpogrelate. However, the effects of M-1 on 5-HT-induced constrictive response in human blood vessels have not been investigated. The internal thoracic artery (ITA) is the key conduit for coronary artery bypass grafting (CABG). 5-HT has been implicated as playing an important role in the pathogenesis of vasospasm. Thus, in the present study, the effects of M-1 on 5-HT-induced vasoconstriction were examined in isolated human endothelium denuded ITA. M-1 inhibited 5-HT-induced vasoconstriction in a concentration-dependent manner. At the highest concentration, M-1 almost completely inhibited the 5-HT-induced vasoconstriction. Expression of 5-HT_2A and 5-HT_1B receptor proteins in the membrane fraction of ITA smooth muscle cells was confirmed by Western blot analysis. Individually, supramaximal concentrations of sarpogrelate and SB224289, a selective 5-HT_1B receptor antagonist, only partially inhibited the 5-HT-induced vasoconstriction. However, simultaneous pretreatment with both these antagonists almost completely inhibited the 5-HT-induced vasoconstriction. The inhibitory effect of M-1 pretreatment mimicked the inhibitory effect of simultaneous pretreatment with sarpogrelate and SB224289. These results suggest that M-1 has antagonistic effects not only on the 5-HT_2A receptor but also on the 5-HT_1B receptor in human ITA smooth muscle cells. M-1 may be useful as a lead compound for the development of drugs for the treatment of 5-HT-induced vasospasms in CABG.

Comparative pathology of human and canine myxomatous mitral valve degeneration: 5HT and TGF-β mechanisms

Myxomatous mitral valve degeneration (MMVD) is a leading cause of valve repair or replacement secondary to the production of mitral regurgitation, cardiac enlargement, systolic dysfunction, and heart failure. The pathophysiology of myxomatous mitral valve degeneration is complex and incompletely understood, but key features include activation and transformation of mitral valve (MV) valvular interstitial cells (VICs) into an active phenotype leading to remodeling of the extracellular matrix and compromise of the structural components of the mitral valve leaflets. Uncovering the mechanisms behind these events offers the potential for therapies to prevent, delay, or reverse myxomatous mitral valve degeneration. One such mechanism involves the neurotransmitter serotonin (5HT), which has been linked to development of valvulopathy in a variety of settings, including valvulopathy induced by serotonergic drugs, Serotonin-producing carcinoid tumors, and development of valvulopathy in laboratory animals exposed to high levels of serotonin. Similar to humans, the domestic dog also experiences naturally occurring myxomatous mitral valve degeneration, and in some breeds of dogs, the lifetime prevalence of myxomatous mitral valve degeneration reaches 100%. In dogs, myxomatous mitral valve degeneration has been associated with high serum serotonin, increased expression of serotonin-receptors, autocrine production of serotonin within the mitral valve leaflets, and downregulation of serotonin clearance mechanisms. One pathway closely associated with serotonin involves transforming growth factor beta (TGF-β) and the two pathways share a common ability to activate mitral valve valvular interstitial cells in both humans and dogs. Understanding the role of serotonin and transforming growth factor beta in myxomatous mitral valve degeneration gives rise to potential therapies, such as 5HT receptor (5HT-R) antagonists. The main purposes of this review are to highlight the commonalities between myxomatous mitral valve degeneration in humans and dogs, with specific regards to serotonin and transforming growth factor beta, and to champion the dog as a relevant and particularly valuable model of human disease that can accelerate development of novel therapies.

The Biochemical Markers Associated with the Occurrence of Coronary Spasm

Coronary artery spasm (CAS) is one of the mechanisms of angina pectoris. Unlike the diagnosis of acute myocardial infarction which is based on the elevation of cardiac markers, the diagnosis of CAS is difficult and sometimes requires sophisticated and risky provocative test which is not widely accepted in China. There is no well-established biomarker for the diagnosis or prediction of CAS. However, there are some biomarkers proven to be associated with the occurrence of CAS. For example, inflammatory factors including C-reactive protein and cytokines, lipoprotein (a), and cystatin-C might be precipitating factor for CAS. Rho-kinase as a mediator involved in multiple mechanisms of CAS, serotonin, and endothelin-1 as powerful vasoconstrictors leading to vasospasm were all observed being elevated in patients with CAS. Thioredoxin and nitrotyrosine reflected the oxidative status and could be observed to be elevated after the occurrence of CAS. In some cases doubted to be CAS without the evidence of provocative test, the blood test for the biomarkers mentioned above could be useful for the diagnosis of CAS.

[Involvement of thrombophilia in coronary thrombosis]

This review of thrombophilia and coronary thrombosis takes into account the "classical" thrombophilia commonly found in venous pathology and the conditions under which their research may be useful in certain forms of arterial thrombosis especially coronary thrombosis. In addition to the classical thrombophilia, exceptional thrombophilia are evoked, which are both factors of venous thrombosis but also arterial thrombosis. There are also thrombophilia that are more specific to the arterial system such as - homocystein which is potentially both a thrombosis factor but also an agent of arterial parietal lesion or - serotonin which is a factor of arterial spasm and especially coronary spasm. Finally, under the term thrombophilia, it is possible to include thrombophilic conditions, in particular cancers and inflammatory conditions.

Blood levels of serotonin are specifically correlated with plasma lysophosphatidylserine among the glycero-lysophospholipids

Backgrounds

Glycero-lysophospholipids (glycero-LPLs), which are known to exert potent biological activities, have been demonstrated to be secreted from activated platelets in vitro; however, their association with platelet activation in vivo has not been yet elucidated. In this study, we investigated the correlations between the blood levels of each glycero-LPL and serotonin, a biomarker of platelet activation, in human subjects to elucidate the involvement of platelet activation in glycero-LPLs in vivo.

Methods and Results

We measured the plasma serotonin levels in 141 consecutive patients undergoing coronary angiography (acute coronary syndrome, n = 38; stable angina pectoris, n = 71; angiographically normal coronary arteries, n = 32) and investigated the correlations between the plasma levels of serotonin and glycero-LPLs. The results revealed the existence of a specific and significant association between the plasma serotonin and plasma lysophosphatidylserine (LysoPS) levels. On the contrary, regular aspirin intake failed to affect the plasma LysoPS levels despite the fact that the plasma lysophosphatidic acid, lysophosphatidylethanolamine, lysophosphatidylglycerol, and lysophosphatidylinositol levels were lower in those who had taken aspirin regularly.

Conclusion

We found a specific positive correlation between the blood levels of serotonin and LysoPS, a new lipid mediator. Thus, LysoPS might be specifically involved in strong platelet activation, which is associated with the release of serotonin.

General Significance

Our present results suggest the possible involvement of LysoPS in the pathogenesis of atherosclerotic diseases.

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A significant positive correlation between the plasma serotonin and lysophosphatidylserine was observed.

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Regular intake of aspirin had no influence on plasma lysophosphatidylserine.

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PS-PLA1 was correlated with lysophosphatidylserine only in acute coronary syndrome.

Platelet serotonin modulates immune functions

This short review addresses immune functions of platelet serotonin. Platelets transport serotonin at a high concentration in dense granules and release it upon activation. Besides haemostatic, vasotonic and developmental modulation, serotonin also influences a variety of immune functions (mediated by different serotonin receptors). First, platelet serotonergic effects are directed against invading pathogens via activation and proliferation of lymphocytes, modulation of cytokine release, and recruitment of neutrophils to sites of acute inflammation by induction of selectin expression on endothelial cells. Second, serotonin levels are elevated in autoimmune diseases, such as asthma or rheumatoid arthritis, and during tissue regeneration after ischemia of myocardium or brain. Specific antagonism of serotonin receptors appears to improve survival after myocardial infarction or sepsis and to attenuate asthmatic attacks in animal models. It will be of great clinical relevance if these findings can be translated into human applications. In conclusion, targeting immune modulatory effects of platelet serotonin may provide novel therapeutic options for common health problems.

Activation of polymorphonuclear leukocytes and increased plasma vasoconstrictors in vasospastic and nonvasospastic angina

BACKGROUND

The cause of coronary vasoconstriction in patients with angina at rest, nonsignificant coronary stenosis, and endothelial dysfunction remains unknown. Our objective was to investigate the association between enhanced coronary vasoconstriction and increased circulating levels of vasoconstrictor agents.

METHODS

Plasma levels of big endothelin-1, serotonin, and superoxide produced by polymorphonuclear leukocytes were measured in 38 patients with stable angina at rest without significant coronary artery stenosis-23 with nonvasospastic angina and 15 with vasospastic angina-and were compared with 10 patients with stable coronary disease and 20 age-matched controls.

RESULTS

Patients with angina at rest showed higher big endothelin-1 (1.28 vs 0.72 fmol/mL, P < 0.001), serotonin (18.0 vs 9.1 ng/mL, P = 0.002), and superoxide produced by polymorphonuclear leukocytes (177 vs 67 nmol/10 × E8 × minutes, P = 0.001) than did controls. Serotonin and superoxide produced by polymorphonuclear leukocytes were also higher than in coronary disease patients (5.4 ng/mL, P = 0.001, and 97 nmol/10 x E8 x minutes, P = 0.005), and big endothelin-1 levels tended to be higher (0.99 fmol/mL, P = 0.073). Moreover, there were no significant differences in these 3 parameters between patients with vasospastic and nonvasospastic angina, and among the latter, between patients with a positive and those with a negative exercise stress test.

CONCLUSION

Systemic plasma levels of agents with the potential to produce coronary vasoconstriction are increased in patients with stable vasospastic or nonvasospastic angina and, hence, may contribute to their angina, increased coronary tone, and impaired vasodilatory capacity. Furthermore, they may establish a mechanistic link between the 2 conditions.