Alpha-Melanocyte-stimulating Hormone Induces Vasodilation and Exerts Cardioprotection Through the Heme-Oxygenase Pathway in Rat Hearts

Evolving Strategies for Use of Phytochemicals in Prevention and Long-Term Management of Cardiovascular Diseases (CVD)

This report describes major pathomechanisms of disease in which the dysregulation of host inflammatory processes is a major factor, with cardiovascular disease (CVD) as a primary model, and reviews strategies for countermeasures based on synergistic interaction between various agents, including drugs and generally regarded as safe (GRAS) natural medical material (NMM), such as Ginkgo biloba, spice phytochemicals, and fruit seed flavonoids. The 15 well-defined CVD classes are explored with particular emphasis on the extent to which oxidative stressors and associated ischemia-reperfusion tissue injury contribute to major symptoms. The four major categories of pharmaceutical agents used for the prevention of and therapy for CVD: statins, beta blockers (β-blockers), blood thinners (anticoagulants), and aspirin, are presented along with their adverse effects. Analyses of major cellular and molecular features of drug- and NMM-mediated cardioprotective processes are provided in the context of their development for human clinical application. Future directions of the evolving research described here will be particularly focused on the characterization and manipulation of calcium- and calcineurin-mediated cascades of signaling from cell surface receptors on cardiovascular and immune cells to the nucleus, with the emergence of both protective and pathological epigenetic features that may be modulated by synergistically-acting combinations of drugs and phytochemicals in which phytochemicals interact with cells to promote signaling that reduces the effective dosage and thus (often) toxicity of drugs.

The Neuropeptide Alpha-Melanocyte-Stimulating Hormone Is Critical for Corneal Endothelial Cell Protection and Graft Survival after Transplantation

Corneal transplantation is the most common form of tissue transplantation. The success of corneal transplantation mainly relies on the integrity of corneal endothelial cells (CEnCs), which maintain tissue transparency by pumping out excess water from the cornea. After transplantation, the rate of CEnC loss far exceeds that seen with normal aging, which can threaten sight. The underlying mechanisms are poorly understood. Alpha-melanocyte-stimulating hormone (α-MSH) is a neuropeptide that is constitutively found in the aqueous humor with both cytoprotective and immunomodulatory effects. The curent study found high expression of melanocortin 1 receptor (MC1R), the receptor for α-MSH, on CEnCs. The effect of α-MSH/MC1R signaling on endothelial function and allograft survival in vitro and in vivo was investigated using MC1R signaling-deficient mice (Mc1re/e mice with a nonfunctional MC1R). Herein, the results indicate that in addition to its well-known immunomodulatory effect, α-MSH has cytoprotective effects on CEnCs after corneal transplantation, and the loss of MC1R signaling significantly decreases long-term graft survival in vivo. In conclusion, α-MSH/MC1R signaling is critical for CEnC function and graft survival after corneal transplantation.

Alpha-melanocyte-stimulating hormone during exercise recovery has prognostic value for coronary artery disease

PURPOSE

Alpha-melanocyte-stimulating hormone (alpha-MSH) has proven cardiovascular effects and plays a significant role as an endogenous countermeasure to ischemia-reperfusion injury. The aim of the current study was to examine the response of alpha-MSH during exercise in patients diagnosed with coronary artery disease (CAD) and evaluate its value in the assessment of severity and prognosis.

METHODS

Forty subjects with documented CAD (i.e., lesions on coronary angiography ≥ 50%) were included. Cardiopulmonary exercise testing (CPET) on a treadmill (TM) and recumbent ergometer (RE) were performed on two visits, 2-4 days apart, during 2 months of coronary angiography; subsequently, the subjects were followed up for 32 ± 10 months. At rest, at peak CPET, and after 3 min of recovery, plasma levels of alpha-MSH were measured by enzyme-linked immunosorbent assay technique.

RESULTS

Mean ejection fraction was 56.7 ± 9.6%. Alpha-MSH similarly increased from rest to peak CPET on both modalities. There were no significant differences in alpha-MSH values during testing in patients with 1,2- and 3-vesel CAD, nor in patients with a SYNTAX score </≥ 23 (p > 0.05). Among CPET and hormonal parameters, ∆alpha-MSH recovery/peak during RE CPET was the best predictor of cardiac event occurrence (chi-square 6.67, HR = 0.51, CI = 0.25-1.02, p = 0.010).

CONCLUSION

∆alpha-MSH recovery/peak during RE CPET has predictive value for CAD prognosis, demonstrating involvement of alpha-MSH in CAD and a link between stress hormones and cardiac events.

Antifibrotic and Anti-Inflammatory Actions of α-Melanocytic Hormone: New Roles for an Old Player

The melanocortin system encompasses melanocortin peptides, five receptors, and two endogenous antagonists. Besides pigmentary effects generated by α-Melanocytic Hormone (α-MSH), new physiologic roles in sexual activity, exocrine secretion, energy homeostasis, as well as immunomodulatory actions, exerted by melanocortins, have been described recently. Among the most common and burdensome consequences of chronic inflammation is the development of fibrosis. Depending on the regenerative capacity of the affected tissue and the quality of the inflammatory response, the outcome is not always perfect, with the development of some fibrosis. Despite the heterogeneous etiology and clinical presentations, fibrosis in many pathological states follows the same path of activation or migration of fibroblasts, and the differentiation of fibroblasts to myofibroblasts, which produce collagen and α-SMA in fibrosing tissue. The melanocortin agonists might have favorable effects on the trajectories leading from tissue injury to inflammation, from inflammation to fibrosis, and from fibrosis to organ dysfunction. In this review we briefly summarized the data on structure, receptor signaling, and anti-inflammatory and anti-fibrotic properties of α-MSH and proposed that α-MSH analogues might be promising future therapeutic candidates for inflammatory and fibrotic diseases, regarding their favorable safety profile.

The alpha-melanocyte stimulating hormone is related to heart rate during exercise recovery

Alpha-melanocyte-stimulating hormone (alpha-MSH) is a part of the hormonal stress system with proven cardiovascular effects. Heart rate recovery (HRR) following exercise is strongly correlated to overall fitness and future adverse cardiovascular events. The current study examined the predictive value of alpha-MSH for HRR following exercise testing.Cardiopulmonary exercise testing (CPET) on a treadmill was used to measure HR and oxygen consumption (V̇O₂) in 16 elite male wrestlers (W), 21 water polo player (WP) and 20 sedentary subjects (C) matched for age. Plasma levels of alpha-MSH were measured by radioimmunoassay technique in four phases of CPET: 1) 10 min pre-CPET at rest; 2) at the initation of CPET; 3) at peak CPET; and 4) at the third minute of recovery. The WP group had significantly higher HRR compared to than W and C groups, who did not have significantly different values. Significant difference in alpha-MSH measurements and patterns during CPET between groups was not observed (p > 0.05). When combining all three groups, we observed a significant correlation between V̇O₂ recovery and alpha-MSH recovery/peak (r = -0.3, p = 0.022). HRR and ΔHRR/peak significantly correlated with alpha-MSH at all four measurment points (r = -0.4; p < 0.01 for all). On multiple regression analysis, which included anthropometric and hormonal measures, the best independent predictor of HRR and ΔHRR/peak was alpha-MSH during recovery (B = -1.0, -0.5; SE = 0.3, 0.1; CI = -1.5 to -0.4, -0.7 to -0.2; p = 0.001 respectively). In conclusion, alpha-MSH measured during exercise recovery holds predictive value for HRR and ΔHRR/peak, suggesting a contributing role to integrative regulation of overall cardiopulmonary performance.

Condensed abstract

Present study examined the predictive value of alpha-melanocyte stimulating hormone (alpha-MSH) for heart rate recovery (HRR) in elite male wrestlers, water polo players and sedentary subjects matched for age. Alpha-MSH measured during exercise recovery holds predictive value for HRR and ΔHRR/peak, suggesting a contributing role to integrative regulation of overall cardiopulmonary performance.

Novel anti-inflammatory and chondroprotective effects of the human melanocortin MC1 receptor agonist BMS-470539 dihydrochloride and human melanocortin MC3 receptor agonist PG-990 on lipopolysaccharide activated chondrocytes

Human melanocortin MC1 and MC3 receptors expressed on C-20/A4 chondrocytes exhibit chondroprotective and anti-inflammatory effects when activated by melanocortin peptides. Nearly 9 million people in the UK suffer from osteoarthritis, and bacterial infections play a role in its development. Here, we evaluate the effect of a panel of melanocortin peptides with different selectivity for human melanocortin MC1 (α-MSH, BMS-470539 dihydrochloride) and MC3 ([DTrp⁸]-γ-MSH, PG-990) receptors and C-terminal peptide α-MSH_11-13(KPV), on inhibiting LPS-induced chondrocyte death, pro-inflammatory mediators and induction of anti-inflammatory proteins. C-20/A4 chondrocytes were treated with a panel of melanocortin peptides prophylactically and therapeutically in presence of LPS (0.1 μg/ml). The chondroprotective properties of these peptides determined by cell viability assay, RT-PCR, ELISA for detection of changes in inflammatory markers (IL-6, IL-8 and MMP-1, -3 and -13) and western blotting for expression of the anti-inflammatory protein heme-oxygenase-1. C-20/A4 expressed human melanocortin MC1 and MC3 receptors and melanocortin peptides elevated cAMP. LPS stimulation caused a reduction in C-20/A4 viability, attenuated by the human melanocortin MC1 receptor agonist BMS-470539 dihydrochloride, and MC3 receptor agonists PG-990 and [DTrp⁸]-γ-MSH. Prophylactic and therapeutic regimes of [DTrp⁸]-γ-MSH significantly inhibited LPS-induced modulation of cartilage-damaging IL-6, IL-8, MMPs -1,-3 and -13 mediators both prophylactically and therapeutically, whilst human melanocortin MC1 and MC3 receptor agonists promoted an increase in HO-1 production. In the presence of LPS, activation of human melanocortin MC1 and MC3 receptors provided potent chondroprotection, upregulation of anti-inflammatory proteins and downregulation of inflammatory and proteolytic mediators involved in cartilage degradation, suggesting a new avenue for osteoarthritis treatment.

Phikud Navakot Modulates the Level of Pro-Inflammatory Mediators and the Protein Expression of SOD1 and 2 and the Nrf2/HO-1 Signaling Pathway in Rats with Acute Myocardial Infarction

Phikud Navakot (PN) is nine major herbs in a famous traditional Thai recipe namely “Yahom Navakot” used to treat cardiovascular disorders. This study investigated the cardioprotective effects of PN formula on isoproterenol-induced myocardial infarction (IMI) in Sprague-Dawley rats. Forty-five rats were randomly divided into nine groups (n = 5 per group): the control, the IMI, the IMI + propranolol, the control or the IMI + PN formula (PN ethanolic extract at doses of 64, 127, or 255 mg/kg) by oroesophageal gavage for 28 days. The ST segment and serum troponin T levels were significantly increased in IMI rats. PN did not eliminate tissue necrosis, infiltration of inflammatory cells, or interstitial edema in IMI rats. All doses of PN decreased (p < 0.001) serum TNF-α and IL-6 levels. PN (127 and 255 mg/kg) up-regulated (p < 0.05) heme oxygenase (HO)-1 expression, whereas PN (255 mg/kg) significantly increased superoxide dismutase (SOD) 1 and 2 expression, compared with IMI rats. Nuclear factor erythroid 2-related factor 2 (Nrf2) and HO-1 expression significantly increased in IMI rats and IMI rats that received PN. PN formula possesses potential anti-inflammatory and antioxidant properties by modulating the levels of TNF-α, IL-6 and antioxidant enzymes. Our study reveals a novel cardioprotective effect of PN in IMI rats through the Nrf2/HO-1 signaling.

Monomethylfumarate protects against ovariectomy-related changes in body composition

Osteoporosis, low bone mass that increases fracture susceptibility, affects approximately 75 million individuals in the United States, Europe and Japan, with the number of osteoporotic fractures expected to increase by more than 3-fold over the next 50 years. Bone mass declines with age, although the mechanisms for this decrease are unclear. Aging enhances production of reactive oxygen species, which can affect bone formation and breakdown. The multiple sclerosis drug Tecfidera contains dimethylfumarate, which is rapidly metabolized to monomethylfumarate (MMF); MMF is thought to function through nuclear factor erythroid-derived-2-like-2 (Nrf2), a transcription factor activated by oxidative stress which induces the expression of endogenous anti-oxidant systems. We hypothesized that MMF-elicited increases in anti-oxidants would inhibit osteopenia induced by ovariectomy, as a model of aging-related osteoporosis and high oxidative stress. We demonstrated that MMF activated Nrf2 and induced anti-oxidant Nrf2 target gene expression in bone marrow-derived mesenchymal stem cells. Sham-operated or ovariectomized adult female mice were fed chow with or without MMF and various parameters monitored. Ovariectomy produced the expected effects, decreasing bone mineral density and increasing body weight, fat mass, bone marrow adiposity and serum receptor activator of nuclear factor-kappa-B ligand (RANKL) levels. MMF decreased fat but not lean mass. MMF improved trabecular bone microarchitecture after adjustment for body weight, although the unadjusted data showed few differences; MMF also tended to increase adjusted cortical bone and to reduce bone marrow adiposity and serum RANKL levels. Because these results suggest the possibility that MMF might be beneficial for bone, further investigation seems warranted.

Protection of cultured brain endothelial cells from cytokine-induced damage by α-melanocyte stimulating hormone

The blood–brain barrier (BBB), an interface between the systemic circulation and the nervous system, can be a target of cytokines in inflammatory conditions. Pro-inflammatory cytokines tumor necrosis factor-α (TNF-α) and interleukin-1β (IL-1β) induce damage in brain endothelial cells and BBB dysfunction which contribute to neuronal injury. The neuroprotective effects of α-melanocyte stimulating hormone (α-MSH) were investigated in experimental models, but there are no data related to the BBB. Based on our recent study, in which α-MSH reduced barrier dysfunction in human intestinal epithelial cells induced by TNF-α and IL-1β, we hypothesized a protective effect of α-MSH on brain endothelial cells. We examined the effect of these two pro-inflammatory cytokines, and the neuropeptide α-MSH on a culture model of the BBB, primary rat brain endothelial cells co-cultured with rat brain pericytes and glial cells. We demonstrated the expression of melanocortin-1 receptor in isolated rat brain microvessels and cultured brain endothelial cells by RT-PCR and immunohistochemistry. TNF-α and IL-1β induced cell damage, measured by impedance and MTT assay, which was attenuated by α-MSH (1 and 10 pM). The peptide inhibited the cytokine-induced increase in brain endothelial permeability, and restored the morphological changes in cellular junctions visualized by immunostaining for claudin-5 and β-catenin. Elevated production of reactive oxygen species and the nuclear translocation of NF-κB were also reduced by α-MSH in brain endothelial cells stimulated by cytokines. We demonstrated for the first time the direct beneficial effect of α-MSH on cultured brain endothelial cells, indicating that this neurohormone may be protective at the BBB.

Long Term Osmotic Mini Pump Treatment with Alpha-MSH Improves Myocardial Function in Zucker Diabetic Fatty Rats

The present investigation evaluates the cardiovascular effects of the anorexigenic mediator alpha-melanocyte stimulating hormone (MSH), in a rat model of type 2 diabetes. Osmotic mini pumps delivering MSH or vehicle, for 6 weeks, were surgically implanted in Zucker Diabetic Fatty (ZDF) rats. Serum parameters, blood pressure, and weight gain were monitored along with oral glucose tolerance (OGTT). Echocardiography was conducted and, following sacrifice, the effects of treatment on ischemia/reperfusion cardiac injury were assessed using the isolated working heart method. Nicotinamide adenine dinucleotide phosphate (NADPH) oxidase activity was measured to evaluate levels of oxidative stress, and force measurements were performed on isolated cardiomyocytes to determine calcium sensitivity, active tension and myofilament co-operation. Vascular status was also evaluated on isolated arterioles using a contractile force measurement setup. The echocardiographic parameters ejection fraction (EF), fractional shortening (FS), isovolumetric relaxation time (IVRT), mitral annular plane systolic excursion (MAPSE), and Tei-index were significantly better in the MSH-treated group compared to ZDF controls. Isolated working heart aortic and coronary flow was increased in treated rats, and higher Hill coefficient indicated better myofilament co-operation in the MSH-treated group. We conclude that MSH improves global heart functions in ZDF rats, but these effects are not related to the vascular status.

A Novel Therapeutic Approach in the Treatment of Pulmonary Arterial Hypertension: Allium ursinum Liophylisate Alleviates Symptoms Comparably to Sildenafil

Right-sided heart failure—often caused by elevated pulmonary arterial pressure—is a chronic and progressive condition with particularly high mortality rates. Recent studies and our current findings suggest that components of Wild garlic (Allium ursinum, AU) may play a role in reducing blood pressure, inhibiting angiotensin-converting enzyme (ACE), as well as improving right ventricle function in rabbit models with heart failure. We hypothesize that AU may mitigate cardiovascular damage caused by pulmonary arterial hypertension (PAH) and has value in the supplementary treatment of the complications of the disease. In this present investigation, PAH was induced by a single dose of monocrotaline (MCT) injection in Sprague-Dawley rats, and animals were divided into 4 treatment groups as follows: I. healthy control animals (Control group); II. pulmonary hypertensive rats (PAH group); III. pulmonary hypertensive rats + daily sildenafil treatment (Sildenafil group); and IV. pulmonary hypertensive rats + Wild garlic liophylisate-enriched chow (WGLL group), for 8 weeks. Echocardiographic measurements were obtained on the 0 and 8 weeks with fundamental and Doppler imaging. Isolated working heart method was used to determinate cardiac functions ex vivo after thoracotomy on the 8th week. Histological analyses were carried out on excised lung samples, and Western blot technique was used to determine Phosphodiesterase type 5 enzyme (PDE5) expression in both myocardial and pulmonary tissues. Our data demonstrate that right ventricle function measured by echocardiography was deteriorated in PAH animals compared to controls, which was counteracted by AU treatment. Isolated working heart measurements showed elevated aortic flow in WGLL group compared to PAH animals. Histological analysis revealed dramatic increase in medial wall thickness of pulmonary arteries harvested from PAH animals, but arteries of animals in sildenafil- and WGLL-treated groups showed physiological status. Our results suggest that bioactive compounds in Allium ursinum could have beneficial effects in pulmonary hypertension.