Heart failure (HF) is a global burden and, irrespective of age, sex, race, nationality, and geography, affects individuals across the world. Several reports mentioned that, globally, more than 64 million people, which accounts for 1% to 3% of the total global population, are living with HF. In the United States, approximately 6.7 million people older than 20 years have some form of HF, and it is expected to rise to 8.5 million (approximately 3% of the US population) by 2030. HF was linked to 85,037 deaths in 2021, which was 45.8% higher than in 2011. The direct and indirect healthcare costs to treat and manage HF keep increasing both in the United States and around the world. There are several different classes of therapeutic agents available to treat HF. The current recommended therapies include the following drug classes: renin-angiotensin-aldosterone system inhibitors, angiotensin receptor-neprilysin inhibitor, diuretics, β-blockers, and sodium-glucose cotransporter inhibitors. The present article reviews the pathophysiology of HF and focuses on the Food and Drug Administration-approved HF therapeutic agents and insights from corresponding clinical studies.

[This corrects the article DOI: 10.14423/SMJ.0000000000001965.].

α-CGRP (alpha-calcitonin gene-related peptide) is a vasoactive and anti-inflammatory neuropeptide that is cardioprotective in transverse aortic constriction (TAC)-induced pressure overload heart failure (HF) models. Our previous investigations established that a peptoid modification of α-CGRP, termed NMEG-CGRP, prevented left ventricular (LV) dysfunction and remodeling when administered subcutaneously every other day for 28 days, starting two days post-TAC surgery (termed prevention study). Here, we determined whether NMEG-CGRP would be cardioprotective when administered after the development of LV dysfunction secondary to TAC surgery (termed treatment study). Starting 15 days post-sham or TAC surgery, we administered NMEG-CGRP (3.6 mg/kg/mouse) subcutaneously every other day for 28 days in mice assigned to treatment groups. In vivo assessments included weekly electrocardiography to evaluate cardiac function and blood sampling for immunophenotyping. On Day 45, mice were euthanized, and hearts were collected for gross, histological, and biochemical analyses. Compared to sham-operated mice, TAC mice exhibited decreased LV ejection fraction and increased hypertrophy, dilation, fibrosis, apoptosis, and oxidative stress. In contrast, TAC mice treated with NMEG-CGRP demonstrated significant improvements in cardiac function and cellular and biochemical parameters when compared to TAC mice. These findings demonstrate the therapeutic potential of NMEG-CGRP in the treatment of established cardiovascular dysfunction and its progression in pressure overload-induced HF.

BackgroundAlpha-calcitonin gene-related peptide (α-CGRP) is a cardioprotective neuropeptide. However, due to low bioavailability, its use as a therapeutic agent is limited. The aim of the present study was to develop a stable and bioactive α-CGRP analog and to determine its cardioprotective effects in a mouse model of heart failure (HF).MethodsWe chemically synthesized a peptide-peptoid hybrid: human α-CGRP containing two monomers of N-methoxy-ethyl glycine peptoid at the N-terminus (NMEG-CGRP). The toxicity, bioactivity, and stability of NMEG-CGRP were determined by MTT-cell viability assay, mouse blood pressure measurement, and in-vitro digestion with Insulin-degrading enzyme (IDE) followed by LC-MS, respectively. Male C57BL6 mice were underwent transverse aortic constriction (TAC) and were divided into: Sham, Sham+NMEG-CGRP, TAC, and TAC+NMEG-CGRP. Two-day post-TAC, NMEG-CGRP (3.6 mg/kg/mouse) was administered subcutaneously on alternate days, for a total of 28 days. Cardiac function was measured weekly using echocardiography. At the endpoint, mice were euthanized, and hearts were collected for analysis.ResultsOur results demonstrated that NMEG-CGRP was non-toxic to rat H9C2 cells, more stable to IDE digestion, and bioactive. TAC-induced pressure-overload decreased ejection fraction and increased cardiac hypertrophy and dilation, fibrosis, apoptosis, oxidative stress, and macrophage infiltration in the left ventricles. NMEG-CGRP administration significantly attenuated these TAC-induced adverse cardiac effects in the HF mice.ConclusionTogether, our results demonstrated that NMEG-CGRP is a non-toxic, stable, and bioactive CGRP-analog, and protects against pressure-induced HF in mice. Thus, NMEG-CGRP is a promising novel CGRP-analog that may be used in the treatment of HF and potentially other cardiac diseases.

Although the cardioprotective role of alpha-calcitonin gene related peptide (α-CGRP), a 37 amino acid vasodilator neuropeptide, is known for heart failure (HF) and other cardiac diseases, low bioavailability of the peptide makes it not feasible to use as a therapeutic agent. To increase the bioavailability of the peptide, our laboratory chemically synthesized an α-CGRP analog (NMEG-CGRP) containing two molecules of N -methoxyethylglycine (NMEG) peptoid at the N-terminus of human α-CGRP. Bioactivity, stability, and toxicity of NMEG-CGRP were assessed. LC-MS mass spectrometry experiments demonstrated that an α-CGRP-degrading enzyme, insulin-degrading enzyme (IDE), cleaved native α-CGRP within 30 min, while NMEG-CGRP remained intact until 1 h indicating that the addition of NMEG-peptoid makes α-CGRP a more stable peptide. NMEG-CGRP did not affect the viability of rat H9C2 cardiac myocyte cells (MTT-cell viability assay) and lowered the systolic pressure (as measured by tail-cuff blood pressure analysis system) in the wild-type mice. The cardioprotective effect of NMEG-CGRP was tested in the transverse aortic constriction (TAC) pressure-overload mouse model of HF. Male C57BL6 mice were divided into 4 groups (n= 6-7 mice): sham, sham+NMEG-CGRP, TAC, and TAC+NMEG-CGRP, and TAC protocol was performed in the respective mouse groups. Two days post-TAC, NMEG-CGRP (3.6 mg/kg/mouse) was administered subcutaneously on alternate days, for a total of 28 days, in the TAC+NMEG-CGRP and sham+NMEG-CGRP mice, and echocardiography was performed weekly to assess cardiac function. At the experimental endpoint, hearts were collected from all mouse groups. The echocardiography data demonstrated that TAC significantly lowered cardiac functions (fractional shortening, FS) in mice, however, NMEG-CGRP delivery significantly improved FS in the TAC+NMEG-CGRP mice. On day 30, the %FS (mean±SD) was: sham= 49.5±1.5, sham+NMEG-CGRP= 47.9±2.3, TAC= 28.3±3.2, and TAC+NMEG-CGRP= 40±1.5. Histological data showed that cardiac cell size, fibrosis, and apoptosis were significantly increased in TAC-mice that was significantly attenuated by NMEG-CGRP in TAC+NMEG-CGRP mice. These studies demonstrated that NMEG-CGRP is a bioactive CGRP-analog and protects the heart against HF at the pathophysiological level. Hence, NMEG-CGRP is a potential therapeutic agent to treat pressure-overload induced HF.

Alpha-calcitonin gene related peptide (α-CGRP) is a potent vasodilator and protects against heart failure and hypertension in various animal models; however, rapid clearance of the peptide from the circulation makes it difficult to use as a therapeutic agent. Recently, we have synthesized two α-CGRP agonist analogs linked with two n-methoxyethylglycine (NMEG) peptoid molecules at either end: 1)- α-CGRP with NMEG molecules at the N-terminal end (N-ter NMEG), and 2)- α-CGRP with NMEG molecules at the C-terminal end (C-ter NMEG). Bioactivity and toxicity of modified peptides were evaluated in in vitro and in vivo conditions. Peptide-peptoid hybrids, N-ter NMEG and C-ter NMEG, were synthesized using a solid-phase peptide synthesis method with a >98% purity. To test the in vitro cell viability of the analogs, rat H9C2 cardiac myocyte cells were treated with 1 μM, 3 μM, and 10 μM concentrations of N-ter NMEG and C-ter NMEG peptides for 4 days followed by an MTT assay. Our in vitro results demonstrated that neither α-CGRP analogs were toxic to H9C2 cells. To test the bioactivity of these peptides, blood pressure (BP) was measured in wild-type C57BL6 mice using a tail-cuff BP analysis system. A bolus dose of 1.2, 3.6, and 12 (in mg/kg b.wt./mouse) of either peptide was injected subcutaneously (n= 4 mice/dose) followed by BP measurement at increasing time points. Our results demonstrate that there is a variance in the bioactivity of the two peptides. Subcutaneous delivery of N-ter NMEG reduced BP similar to the native peptide. After ten minutes of N-ter NMEG delivery, the BP (in mmHg ±SD) at a dose of 1.2 mg/kg was 76 ±5 (baseline BP= 118 ±15), at a dose of 3.6 mg/kg was 79 ±7 (baseline BP= 113 ±9), and at a dose of 12 mg/mg was 83 ±12 (baseline BP= 104 ±6). In contrast, C-ter NMEG administration did not reduce BP at any peptide concentration tested. In summary, in this study we determined that the α-CGRP analog N-ter NMEG, but not C-ter NMEG, is bioactive. Furthermore, N-ter NMEG showed no toxic effects on H9C2 cardiac myocytes in an in vitro viability assay. These results demonstrate that the analog N-ter NMEG is an effective α-CGRP agonist and a promising candidate molecule to treat cardiac diseases.

Alpha-calcitonin gene-related peptide (α-CGRP) and adrenomedullin (AM) are vasoactive peptides that belong to the calcitonin/CGRP peptide superfamily. Numerous studies have established a protective role of α-CGRP and AM in normal cardiovascular function and the pathophysiology of several cardiovascular diseases. Administration of AM or α-CGRP reduces blood pressure in both the hypertensive and normotensive state. Exogenous delivery of AM or α-CGRP significantly protects the heart secondary to hypertension and heart failure. The short half-life of the peptides in the serum, however, has hindered its ability to be an effective treatment option. Additionally, α-CGRP has been shown to play a significant role in precipitating migraine headaches. Hence, α-CGRP antagonists reduce migraine pain and the number of episodes. Currently, four α-CGRP antagonists are approved for the treatment of migraine. Thus, AM/α-CGRP-agonist(s) and α-CGRP-antagonist(s) are clinically relevant agents in the treatment of cardiovascular diseases and migraine, respectively.

Alpha-calcitonin gene-related peptide (α-CGRP) is a vasodilator neuropeptide of the calcitonin gene family. Pharmacological and gene knock-out studies have established a significant role of α-CGRP in normal and pathophysiological states, particularly in cardiovascular disease and migraines. α-CGRP knock-out mice with transverse aortic constriction (TAC)-induced pressure-overload heart failure have higher mortality rates and exhibit higher levels of cardiac fibrosis, inflammation, oxidative stress, and cell death compared to the wild-type TAC-mice. However, administration of α-CGRP, either in its native- or modified-form, improves cardiac function at the pathophysiological level, and significantly protects the heart from the adverse effects of heart failure and hypertension. Similar cardioprotective effects of the peptide were demonstrated in pressure-overload heart failure mice when α-CGRP was delivered using an alginate microcapsules-based drug delivery system. In contrast to cardiovascular disease, an elevated level of α-CGRP causes migraine-related headaches, thus the use of α-CGRP antagonists that block the interaction of the peptide to its receptor are beneficial in reducing chronic and episodic migraine headaches. Currently, several α-CGRP antagonists are being used as migraine treatments or in clinical trials for migraine pain management. Overall, agonists and antagonists of α-CGRP are clinically relevant to treat and prevent cardiovascular disease and migraine pain, respectively. This review focuses on the pharmacological and therapeutic significance of α-CGRP-agonists and -antagonists in various diseases, particularly in cardiac diseases and migraine pain.

The cardioprotective role of a neuropeptide, alpha-calcitonin gene related peptide (αCGRP), has been established in a variety of cardiovascular diseases. To increase the bioavailability of the circulating peptide, we created a peptide delivery system by encapsulating αCGRP in an alginate biopolymer and showed that subcutaneous delivery of alginate-αCGRP microcapsules (αCGRP dose= 6 mg/kg/mouse) on alternate days, up to 28 days, significantly protected hearts at pathophysiological levels in a transverse aortic constriction (TAC) pressure-overload induced heart failure murine model. The present study was performed to determine if weekly subcutaneous delivery of alginate-αCGRP microcapsules exhibited similar cardioprotective effects in TAC-mice as observed in our previous study with alternate days dose delivery scheme. This study is crucial to shed light on the efficacy of these microcapsules. An electrospray method was used to prepare alginate-αCGRP microcapsules of 200 μm diameter. Male C57BL6 mice were divided into four groups (3 mice/group): i- sham, ii- sham-alginate-CGRP, iii- TAC, and iv- TAC-alginate-CGRP. Mice from TAC and TAC-alginate-CGRP groups underwent TAC procedure. Two days post-TAC, alginate-αCGRP microcapsules (αCGRP dose= 6 mg/kg/mouse) were administered subcutaneously once a week, up to 4 weeks, in the respective alginate-CGRP groups of mice. Short-axis echocardiography was performed to evaluate cardiac functions. After 28 days of microcapsules delivery, calculated percent fractional shortening (FS) and ejection fraction (EF) in mice were (in ±SD)- sham: FS= 47.6 ± 0.9, EF= 79.8 ± 0.9; sham-alginate-CGRP: FS= 47.3 ± 1.9, EF= 79.1 ± 2; TAC: FS= 34.1 ± 4.7, EF= 63.6 ± 7.1; TAC-alginate-CGRP: FS= 32.2 ± 2.3, EF= 61.0 ± 3.4. These echo data demonstrate that TAC heart failure mice had the usual significantly reduced cardiac functions, however weekly delivery of alginate-αCGRP microcapsules showed no improvement in heart performance in the TAC-mice. Combined results from our present and previous studies suggested that alginate-αCGRP microcapsules delivery on alternate days, but not weekly, is the most efficacious choice to achieve cardioprotective effects of αCGRP against pressure-induced heart failure in mice.

Alpha-calcitonin gene related peptide (α-CGRP) is a promising neuropeptide for the treatment of cardiovascular disease. We have developed an alginate biomaterial-based delivery system which increases the peptide’s bioavailability and have shown that subcutaneous delivery of alginate-CGRP microcapsules significantly improved cardiac function in pressure overload-induced heart failure in mice. The goal of this study is to develop efficient alginate microcapsule formulations for oral delivery of α-CGRP. An electrospray method was used to prepare four different formulations of alginate-CGRP microcapsules all of 200 μm diameter- i)- alginate-CGRP microcapsules, ii)- alginate-CGRP microcapsules with UV-light exposure, iii)- poly-L-ornithine (PLO) coated alginate-CGRP microcapsules, and iv)- PLO alginate-CGRP microcapsules with UV-light exposure. The stability of the microcapsules in the digestive tract was evaluated in deionized water, simulated gastric fluid (SGF; pH 1.2), and simulated intestinal fluid (SIF; pH 6.8). Over time, the size of all four microcapsule formulations remained almost unchanged in SGF, however all four of the microcapsule formulations swelled in presence of SIF. Compared to deionized water, the size of alginate-CGRP microcapsules after 6 h incubation in SIF increased by 1.7 fold. Since all four formulations yielded similar results, we chose to further study the alginate-CGRP microcapsules in vivo . To determine the bioactive nature of the released peptide, alginate microcapsules containing α-CGRP in doses of 1, 3, and 10 (mg/kg b.wt) were fed to male C57BL/6 mice via oral gavage. Systolic blood pressure (SBP) was subsequently measured by a tail-cuff method. α-CGRP microcapsules reduced SBP in a time-dependent manner. Alginate-CGRP at 1 and 3 mg/kg lowered the SBP by 25 mmHg for up to 4 h and 48 h, respectively. However, 10 mg/kg alginate-CGRP initially reduced SBP to undetectable levels which ultimately returned to baseline level by day 7. These studies indicate that alginate microcapsules can withstand the low pH of the stomach and the release of the peptide is bioactive in vivo . Thus, alginate microcapsules may provide an ideal formulation to deliver α-CGRP orally for the long-term treatment of cardiac diseases.

Background: α-CGRP (alpha-calcitonin gene related peptide) is a cardioprotective neuropeptide. Our recent study demonstrated that the administration of native α-CGRP, using osmotic mini-pumps, protected against transverse aortic constriction (TAC) pressure-induced heart failure in mice. However, the short half-life of peptides and the non-applicability of osmotic pumps in humans limits the use of α-CGRP as a therapeutic agent for heart failure (HF). Here, we sought to comprehensively study a novel α-CGRP delivery system using alginate microcapsules to determine its bioavailability in vivo and to test for cardioprotective effects in HF mice. Methods: Native α-CGRP filled alginate microcapsules (200 µm diameter) were prepared using an electrospray method. The prepared alginate-α-CGRP microcapsules were incubated with rat cardiac H9c2 cells, mouse cardiac HL-1 cells, and human umbilical vein endothelial cells (HUVECs), and the cytotoxicity of the alginate-α-CGRP microcapsules was measured by a trypan-blue cell viability assay and a calcium dye fluorescent based assay. The efficacy of the alginate-α-CGRP microcapsules was tested in a TAC-pressure overload mouse model of heart failure. Male C57BL6 mice were divided into four groups: sham, sham-alginate-α-CGRP, TAC-only, and TAC-alginate-α-CGRP, and the TAC procedure was performed in the TAC-only and TAC-alginate-α-CGRP groups of mice to induce pressure-overload heart failure. After 2 or 15 days post-TAC, alginate-α-CGRP microcapsules (containing an α-CGRP dose of 6 mg/kg/mouse) were administered subcutaneously on alternate days, for 28 days, and echocardiography was performed weekly. After 28 days of peptide delivery, the mice were sacrificed and their hearts were collected for histological and biochemical analyses. Results: Our in vitro cell culture assays showed that alginate-α-CGRP microcapsules did not affect the viability of the cell lines tested. The alginate-α-CGRP microcapsules released their peptides for an extended period of time. Our echocardiography, biochemical, and histology data from HF mice demonstrated that the administration of alginate-α-CGRP microcapsules significantly improved all cardiac parameters examined in TAC-mice. When compared to sham mice, TAC significantly decreased cardiac functions (as determined by fraction shortening and ejection fraction) and markedly increased heart and lung weight, left ventricle (LV) cardiac cell size, cardiac apoptosis, and oxidative stress. In contrast, the administration of alginate-α-CGRP microcapsules significantly attenuated the increased heart and lung weight, LV cardiac cell size, apoptosis, and oxidative stress in TAC mice. Conclusion: Our results demonstrate that the encapsulation of α-CGRP in an alginate polymer is an effective strategy to improve peptide bioavailability in plasma and increase the duration of the therapeutic effect of the peptide throughout the treatment period. Furthermore, alginate mediates α-CGRP delivery, either prior to the onset or after the initiation of the symptom progression of pressure-overload, improves cardiac function, and protects hearts against pressure-induced HF.

Alpha-calcitonin gene related peptide (α-CGRP) is a 37-amino acid cardioprotective neuropeptide. Studies carried out in our laboratory and others establish α-CGRP as a potential therapeutic agent against a variety of cardiovascular diseases. However, the short half-life of α-CGRP limits its use in any long-term treatment regime. The goal of the present study is to develop an α-CGRP agonist analog with extended bioavailability using peptoid chemistry. A peptoid is a N -substituted glycine peptidomimetic molecule and is identical to α-amino acid except that the side chain in a peptoid is attached on the nitrogen rather than the α-carbon atom. Inclusion of a peptoid makes the native peptide protease-resistant and thus biostable in vivo . Using a solid-phase submonomer method, we synthesized a novel human α-CGRP analog containing two monomers of N -methoxyethylglycine (NMEG) peptoid at the N-terminus. Electrospray mass spectrometry (MALDI-TOF) analysis showed that the molecular mass of synthesized peptoid-peptide hybrid, NMEG-α-CGRP, was 4044 that is ~6.7% more than native peptide. An in vitro trypan blue cell exclusion assay demonstrated that incubation of NMEG-α-CGRP (5 μM) for 7 days did not affect the viability of rat H9C2 and mouse HL-1 cardiac cells. To evaluate the biological activity of NMEG-α-CGRP, a subcutaneous injection of human α-CGRP (10 μg/mice) and NMEG-α-CGRP (1, 3, 10, and 30 μg/mice) were given in 9-week-old C57BL6 mice (n=2 mice/dose), and blood pressure (BP) was measured using a tail-cuff method. A dose response curve showed that NMEG-α-CGRP decreased BP in mice in a time-dependent manner. Beginning with and injection of 3 μg of NMEG-α-CGRP, a dip in BP (85 ± 1 mmHg; in ±SD) was observed at 10 min after injection, and BP returned to baseline (125 mmHg) by 6 h, 18 h, and 24 h when injected with 3, 10, and 30 μg doses, respectively. Moreover, 10 μg of human-α-CGRP and NMEG-α-CGRP lowered BP from baseline for 2 h and 18 h, respectively, suggesting that NMEG addition increased stability, and thus bioavailability, of α-CGRP in vivo . In summary, our results show that a NMEG based α-CGRP modification is an effective approach to increase stability and, thus, bioavailability of α-CGRP in vivo making α-CGRP a viable therapeutic drug to treat cardiovascular diseases.

Heart failure and cardiovascular disease (CVD) is number one worldwide killer of men and women, including the United States.On the basis of 2016 mortality data, CVD currently claims more lives each year than cancer and chronic lung disease combined.Globally, more than 17 million deaths in year 2016 were caused by CVD that was 14.5% more than year 2006, and it is expected to rise to >23.6 million deaths by year 2030.In the United States, nearly 1 in 3 deaths is accounted by the CVD.In year 2015, ~41.5% of the U.S. population had at least one CVD condition (www.cdc.gov), and The American Heart Association (AHA) estimates that by 2035, 45.1% of the US population would have some form of CVD.The prevalence of CVD in adults (≥20 years of age) is 48.0% and increases with age in both males and females.These numbers show that cardiac and related diseases are placing a heavy financial burden in the economy and the health care system.The total costs (direct and indirect treatment) of CVD in the USA continue to rise-in year 2016 it was $555 billion and is expected to reach $1.1 trillion in year 2035.Although there are several classes of drugs are available to treat and prevent cardiac diseases, the 5-year survival rate is still only 50%.

The cardioprotective role of α-calcitonin gene related peptide (α-CGRP), a 37-amino acid neuropeptide and potent vasodilator, in cardiac diseases has been established by our laboratory and others. Systemic delivery of α-CGRP decreases blood pressure in hypertensive humans, and improves hemodynamic variables in congestive heart failure (CHF) patients. However, the short half-life of the peptide (t 1/2 = ~5.5 min in serum) limits α-CGRP use in any long-term treatment regime. The present study utilized alginate-α-CGRP microcapsules for long-term continuous delivery of α-CGRP in a mouse CHF model. We used an electrospray method to prepare α-CGRP encapsulated alginate microcapsules approximately 200μm in size. The α-CGRP encapsulated microcapsules showed no cytotoxicity when incubated with the cardiac cell lines, HL-1 and H9c2 cells, for 7 days. Subcutaneous administration of microcapsules containing 150, 250, or 500μg α-CGRP lowered the systolic pressure up to 18 h, 3 days, and 7 days, respectively, in wild-type mice (measured by tail-cuff method), indicating that released α-CGRP remains biologically active. The cardioprotective effect of microcapsules released α-CGRP was examined using a transverse aortic constriction (TAC) induced pressure-overload mouse model of CHF. After two days of TAC, 500μl of alginate-α-CGRP microcapsules (containing 150μg α-CGRP) was administered in nine weeks old C57/BL6 mice on alternate days up to 28 days. Echocardiography data showed that microcapsule treatment of α-CGRP significantly preserved left ventricular fraction shortening (FS) and ejection fraction in the TAC mice (FS±SD: sham 47.2±1.5%, sham-alginate-α-CGRP 48.4±1.8%, TAC 29.5±1.4%, and TAC-alginate-α-CGRP 43.2±1.2%). α-CGRP delivery attenuated cardiac hypertrophy in TAC mice when reported as heart wt/tibia length (mg/mm±SD): sham 6.3±0.1, sham-alginate-α-CGRP 6.3±0.2, TAC 8.6±0.3, and TAC-alginate-α-CGRP 6.6±0.2. Alginate-only microcapsules did not affect these cardiac parameters. Our results show that α-CGRP delivery through alginate microcapsules protect hearts from cardiac failure. As alginate is immunologically inactive, the alginate microcapsules offer a new potential delivery paradigm for patients with heart failure.

Alpha-calcitonin gene-related peptide (alpha-CGRP) is a 37-amino acid neuropeptide that plays an important protective role in modulating cardiovascular diseases. Deletion of the alpha-CGRP gene increases the vulnerability of the heart to pressure-induced heart failure and the administration of a modified alpha-CGRP agonist decreases this vulnerability. Systemic administration of alpha-CGRP decreases blood pressure in normotensive and hypertensive animals and humans. Here we examined the protective effect of long-term administration of native alpha-CGRP against pressure-overload heart failure and the likely mechanism(s) of its action. Transverse aortic constriction (TAC) was performed to induce pressure-overload heart failure in mice. We found that TAC significantly decreased left ventricular (LV) fractional shortening, ejection fraction, and alpha-CGRP content, and increased hypertrophy, dilation, and fibrosis compared to sham mice. Administration of alpha-CGRP-filled mini-osmotic pumps (4 mg/kg bwt/day) in TAC mice preserved cardiac function and LV alpha-CGRP levels, and reduced LV hypertrophy, dilation, and fibrosis to levels comparable to sham mice. Additionally, TAC pressure-overload significantly increased LV apoptosis and oxidative stress compared to the sham mice but these increases were prevented by alpha-CGRP administration. alpha-CGRP administration in TAC animals decreased LV AMPK phosphorylation levels and the expression of sirt1, both of which are regulatory markers of oxidative stress and energy metabolism. These results demonstrate that native alpha-CGRP is protective against pressure-overload induced heart failure. The mechanism of this cardio-protection is likely through the prevention of apoptosis and oxidative stress, possibly mediated by sirt1 and AMPK. Thus, alpha-CGRP is a potential therapeutic agent in preventing the progression to heart failure, and the cardio-protective action of alpha-CGRP is likely the result of a direct cellular effect; however, a partial vasodilatory blood pressure-dependent mechanism of alpha-CGRP cannot be excluded.

α-Calcitonin gene-related peptide (α-CGRP) is a regulatory neuropeptide of 37 amino acids. It is widely distributed in the central and peripheral nervous system, predominantly in cell bodies of the dorsal root ganglion (DRG). It is the most potent vasodilator known to date and has inotropic and chronotropic effects. Using pharmacological and genetic approaches, our laboratory and other research groups established the protective role of α-CGRP in various cardiovascular diseases such as heart failure, experimental hypertension, myocardial infarction, and myocardial ischemia/reperfusion injury (I/R injury). α-CGRP acts as a depressor to attenuate the rise in blood pressure in three different models of experimental hypertension: (1) DOC-salt, (2) subtotal nephrectomy-salt, and (3) L-NAME-induced hypertension during pregnancy. Subcutaneous administration of α-CGRP lowers the blood pressure in hypertensive and normotensive humans and rodents. Recent studies also demonstrated that an α-CGRP analog, acylated α-CGRP, with extended half-life (~7 h) reduces blood pressure in Ang-II-induced hypertensive mouse, and protects against abdominal aortic constriction (AAC)-induced heart failure. Together, these studies suggest that α-CGRP, native or a modified form, may be a potential therapeutic agent to treat patients suffering from cardiac diseases.

Congestive heart failure (CHF) is the leading cause of mortality in men and women world-wide, despite multiple but limited treatment modalities. Our laboratory and others have established that α-calcitonin gene-related peptide (αCGRP) plays a significant protective role in several cardiovascular diseases. αCGRP is a 37-amino acid neuropeptide and potent vasodilator. In αCGRP-knockout mice, pressure overload significantly exacerbates cardiac hypertrophy, dysfunction and fibrosis. The present study was performed to determine if exogenous delivery of native αCGRP was cardio-protective against pressure overload-induced CHF. Transverse aortic constriction (TAC) was performed to induce pressure overload CHF in nine week old C57/BL6 mice. One group were sham-treated, one TAC alone, and one TAC plus αCGRP (4 mg/kg bwt/day) via an implanted mini-osmotic pump. All mice had serial echocardiography performed and were sacrificed and hearts collected after 28 days. ELISA data showed that αCGRP levels in the TAC left ventricle (LV) were significantly lower compared to sham LV, while αCGRP in the TAC-CGRP LVs was similar to sham levels. TAC alone significantly decreased fractional shortening (FS) and ejection fraction (EF), and increased cardiac hypertrophy, apoptosis, and fibrosis in the LV compared to sham mice. αCGRP in the TAC mice significantly preserved LV FS and EF, (FS ±SEM: sham 46.2±1.8%, TAC 25.4±1.1%, and TAC-CGRP 36.6±1.2%; EF ±SEM: sham 78±1.9%, TAC 51.3±1.5%, and TAC-CGRP 67.4±1.5%) and attenuated apoptosis (measured by cleaved caspase-3 and TUNEL staining), fibrosis, and oxidative stress (measured by lipid peroxidation, glutathione, and 8-OHdG levels) compared to TAC alone. Moreover, TAC increased the expression of sirtuin proteins (Sirt1, 2, 3, 5, and 7) and phosphorylation of AMPK, both of which are involved in oxidative stress and energy metabolism. This increase in Sirt-1 and -2 protein level was significantly attenuated by αCGRP. In addition, αCGRP markedly reduced phospho-AMPK level in the TAC LV back to control levels. Our results show that αCGRP protects against pressure-induced CHF which may be mediated by the inhibition of myocyte apoptosis and reduction in oxidative stress. Thus, αCGRP is an exciting therapeutic agent in CHF.

Introduction: Calcitonin gene-related peptide (CGRP), a 37 amino acid neuropeptide, is a potent vasodilator, and plays a critical role in the efferent functions of the sensory nervous system. A protective role for CGRP in cardiovascular diseases (hypertension, cardiac ischemia, and failure) has been well established by our laboratory and others. In the present study we determined whether long-term exogenous administration of α-CGRP protects against pressure-induced heart failure. Method: Three groups of nine-week-old C57/BL6 mice were studied: one group received a sham procedure (n= 4) and two groups underwent transverse aortic constriction (TAC). Two days after TAC, one group had CGRP-filled osmotic pumps (4 mg/kg bwt/day) implanted subcutaneously (n= 7) while the second group was TAC-only (n=6). At day 28, all groups had echocardiography performed and were sacrificed and heart tissue collected. Results: Echocardiographic and histological data showed that TAC markedly decreased fractional shortening (FS) and ejection fraction and increased heart and lung weight, cardiac hypertrophy, and fibrosis compared to sham. However, the TAC-CGRP mice had preserved cardiac function and less cardiac fibrosis (FS ±SEM: sham 46.2±1.8% vs TAC 25.4±1.1%, p < 0.001; and TAC 25.4±1.1% vs TAC-CGRP 36.6±1.2%, p < 0.001). CGRP significantly reduced apoptotic cell death and lipid peroxidation (an oxidative stress marker measured by malondialdehyde and 4-HNE staining) in the TAC hearts [malondialdehyde (nmol/mg protein) ±SEM: sham 3.5±0.19 vs TAC 14.3±0.57, p < 0.05; and TAC 14.3±0.57 vs TAC-CGRP 5.5±0.12, p < 0.05]. TAC alone decreased the level of p-ERK1/2 and increased p-JNK compared to sham. CGRP-TAC hearts had higher p-ERK1/2 levels but equal p-JNK levels compared to the TAC hearts. HIF1α and nrf2 protein levels were not different between experimental groups. Compared to TAC hearts, TAC-CGRP hearts had lower p-AMPK and nuclear Sirt1 level, regulatory proteins of energy metabolism. Conclusion: Our results suggest that CGRP, mediated through energy metabolic, and oxidative stress pathways, decreases myocyte apoptosis and is protective in pressure-induced heart failure. Thus, CGRP is a potential therapeutic agent in preventing the progression of heart failure.

BACKGROUND:Tissue-transglutaminase (TG2), a dual function G-protein, plays key roles in cell differentiation and migration. In our previous studies we reported the mechanism of TG2-induced cell differentiation. In present study, we explored the mechanism of how TG2 may be involved in cell migration.METHODS:To study the mechanism of TG2-mediated cell migration, we used neuroblastoma cells (SH-SY5Y) which do not express TG2, neuroblastoma cells expressing exogenous TG2 (SHYTG2), and pancreatic cancer cells which express high levels of endogenous TG2. Resveratrol, a natural compound previously shown to inhibit neuroblastoma and pancreatic cancer in the animal models, was utilized to investigate the role of TG2 in cancer cell migration. Immunofluorescence assays were employed to detect expression and intracellular localization of TG2, and calcium levels in the migrating cells. Native gel electrophoresis was performed to analyze resveratrol-induced cellular distribution and conformational states of TG2 in migrating cells. Data are presented as the mean and standard deviation of at least 3 independent experiments. Comparisons were made among groups using one-way ANOVA followed by Tukey-Kramer ad hoc test.RESULTS:TG2 containing cells (SHYTG2 and pancreatic cancer cells) exhibit increased cell migration and invasion in collagen-coated and matrigel-coated transwell plate assays, respectively. Resveratrol (1 μM-10 μM) prevented migration of TG2-expressing cells. During the course of migration, resveratrol increased the immunoreactivity of TG2 without affecting the total TG2 protein level in migrating cells. In these cells, resveratrol increased calcium levels, and depletion of intracellular calcium by a calcium chelator, BAPTA, attenuated resveratrol-enhanced TG2 immunoreactivity. In native-polyacrylamide gels, we detected an additional TG2 protein band with slower migration in total cell lysates of resveratrol treated cells. This TG2 form is non-phosphorylated, exclusively present in plasma membrane fractions and sensitive to intracellular Ca(2+) concentration suggesting a calcium requirement in TG2-regulated cell migration.CONCLUSIONS:Taken together, we conclude that resveratrol induces conformational changes in TG2, and that Ca(2+)-mediated TG2 association with the plasma membrane is responsible for the inhibitory effects of resveratrol on cell migration.

Glucose uptake by Plasmodium-infected erythrocytes (RBC) is higher compared to uninfected RBC. Glucose is transported across the cell membrane by transporter proteins. Particles of median size 146.3±18.7nm, containing anti-malarial agents in corn starch were prepared for investigating: (a) whether the glucose moiety in starch targets RBC via hexose transporter(s), (b) whether there are differences in the extent of targeting to uninfected RBC versus infected RBC (iRBC) in view of higher cell surface density of these proteins on iRBC and (c) whether targeting provides enhanced efficacy against P. falciparum in comparison to drugs in solution. Binding of these particles to RBC was target-specific, since it could be blocked by phloretin, an inhibitor of glucose transporters (GLUT), or competed out in a dose-dependent manner with d-glucose in a flow cytometry assay. Significant (P=0.048, t-test) differences in extent of targeting to iRBC versus RBC were observed in flow cytometry. CDRI 97/63 incorporated in particles was 63% more efficacious than its solution at 250ng/ml, while quinine was 20% more efficacious at 6.25ng/ml in a SYBR Green incorporation assay. Preferential targeting of iRBC using an inexpensive excipient promises advantages in terms of dose reduction and toxicity alleviation.