A Novel α-Calcitonin Gene-Related Peptide Analogue Protects Against End-Organ Damage in Experimental Hypertension, Cardiac Hypertrophy, and Heart Failure

The hydrogen sulfide donor 4-carboxyphenyl-isothiocyanate decreases blood pressure and promotes cardioprotective effect through reduction of oxidative stress and nuclear factor kappa B/matrix metalloproteinase (MMP)-2 axis in hypertension

AIMS

Our aim was to evaluate whether the hydrogen sulfide (H2S) donor, 4-carboxyphenyl-isothiocyanate (4-CPI), exerts cardioprotective effect in the two kidney- one clip (2K-1C) rats through oxidative stress and MMP-2 activity attenuation and compare it with the classical H2S donor, Sodium Hydrosulfide (NaHS).

MATERIALS AND METHODS

Renovascular hypertension (two kidneys-one clip; 2K-1C) was surgically induced in male Wistar rats. After two weeks, normotensive (2K) and hypertensive rats were intraperitoneally treated with vehicle (0.6 % dimethyl sulfoxide), NaHS (0.24 mg/Kg/day) or with 4-CPI (0.24 mg/Kg/day), for more 4 weeks. Systolic blood pressure (SBP) was evaluated weekly by tail-cuff plethysmography. Heart function was assessed by using the Millar catheter. Cardiac hypertrophy and fibrosis were evaluated by hematoxylin and eosin, and Picrosirius Red staining, respectively. The H2S was analyzed using WSP-1 fluorimetry and the cardiac oxidative stress was measured by lucigenin chemiluminescence and Amplex Red. MMP-2 activity was measured by in-gel gelatin or in situ zymography assays. Nox1, gp91phox, MMP-2 and the phospho-p65 subunit (Serine 279) nuclear factor kappa B (NF-κB) levels were evaluated by Western blotting.

KEY FINDINGS

4-CPI reduced blood pressure in hypertensive rats, decreased cardiac remodeling and promoted cardioprotection through the enhancement of cardiac H2S levels. An attenuation of oxidative stress, with inactivation of the p65-NF-κB/MMP-2 axis was similarly observed after NaHS or 4-CPI treatment in 2K-1C hypertension.

SIGNIFICANCE

H2S is a mediator that promotes cardioprotective effects and decreases blood pressure, and 4-CPI seems to be a good candidate to reverse the maladaptive remodeling and cardiac dysfunction in renovascular hypertension.

Causality between migraine and cardiovascular disease: a bidirectional Mendelian randomization study

BACKGROUND

While growing evidence suggests a relationship between migraine and cardiovascular disease, the genetic evidence for a causal relationship between migraine and cardiovascular disease is still scarce. Investigating the causal association between migraine and cardiovascular disease is vital.

METHODS

We carried out a bidirectional Mendelian randomization (MR) study including discovery samples and replication samples using publicly available genome-wide association study (GWAS) summary datasets and stringent screening instrumental variables. Four different MR techniques-Inverse variance weighted (IVW), MR ‒Egger, weighted median, and weighted mode-as well as various sensitivity analyses-Cochran's Q, IVW radial, leave-one-out (LOO), and MR-PRESSO-were utilized to investigate the causal relationship between cardiovascular disease and migraine.

RESULTS

The protective causal effects of genetically predicted migraine on coronary artery disease (OR, 0.881; 95% CI 0.790-0.982; p = 0.023) and ischemic stroke (OR, 0.912; 95% CI 0.854-0.974; p = 0.006) were detected in forward MR analysis but not in any other cardiovascular disease. Consistently, we also discovered protective causal effects of coronary atherosclerosis (OR, 0.865; 95% CI 0.797-0.940; p = 0.001) and myocardial infarction (OR, 0.798; 95% CI 0.668-0.952; p = 0.012) on migraine in reverse MR analysis.

CONCLUSION

We found a potential protective effect of migraine on coronary artery disease and ischemic stroke and a potential protective effect of coronary atherosclerosis and myocardial infarction on migraine. We emphasised epidemiological and genetic differences and the need for long-term safety monitoring of migraine medications and future research to improve cardiovascular outcomes in migraine patients.

Transient Receptor Potential Canonical 5 (TRPC5): Regulation of Heart Rate and Protection against Pathological Cardiac Hypertrophy

TRPC5 is a non-selective cation channel that is expressed in cardiomyocytes, but there is a lack of knowledge of its (patho)physiological role in vivo. Here, we examine the role of TRPC5 on cardiac function under basal conditions and during cardiac hypertrophy. Cardiovascular parameters were assessed in wild-type (WT) and global TRPC5 knockout (KO) mice. Despite no difference in blood pressure or activity, heart rate was significantly reduced in TRPC5 KO mice. Echocardiography imaging revealed an increase in stroke volume, but cardiac contractility was unaffected. The reduced heart rate persisted in isolated TRPC5 KO hearts, suggesting changes in basal cardiac pacing. Heart rate was further investigated by evaluating the reflex change following drug-induced pressure changes. The reflex bradycardic response following phenylephrine was greater in TRPC5 KO mice but the tachycardic response to SNP was unchanged, indicating an enhancement in the parasympathetic control of the heart rate. Moreover, the reduction in heart rate to carbachol was greater in isolated TRPC5 KO hearts. To evaluate the role of TRPC5 in cardiac pathology, mice were subjected to abdominal aortic banding (AAB). An exaggerated cardiac hypertrophy response to AAB was observed in TRPC5 KO mice, with an increased expression of hypertrophy markers, fibrosis, reactive oxygen species, and angiogenesis. This study provides novel evidence for a direct effect of TRPC5 on cardiac function. We propose that (1) TRPC5 is required for maintaining heart rate by regulating basal cardiac pacing and in response to pressure lowering, and (2) TRPC5 protects against pathological cardiac hypertrophy.

Functional Analysis of TRPA1, TRPM3, and TRPV1 Channels in Human Dermal Arteries and Their Role in Vascular Modulation

Transient receptor potential (TRP) channels are pivotal in modulating vascular functions. In fact, topical application of cinnamaldehyde or capsaicin (TRPA1 and TRPV1 channel agonists, respectively) induces "local" changes in blood flow by releasing vasodilator neuropeptides. We investigated TRP channels' contributions and the pharmacological mechanisms driving vasodilation in human isolated dermal arteries. Ex vivo studies assessed the vascular function of artery segments and analyzed the effects of different compounds. Concentration-response curves to cinnamaldehyde, pregnenolone sulfate (PregS, TRPM3 agonist), and capsaicin were constructed to evaluate the effect of the antagonists HC030031 (TRPA1); isosakuranetin (TRPM3); and capsazepine (TRPV1). Additionally, the antagonists/inhibitors olcegepant (CGRP receptor); L-NAME (nitric oxide synthase); indomethacin (cyclooxygenase); TRAM-34 plus apamin (K+ channels); and MK-801 (NMDA receptors, only for PregS) were used. Moreover, CGRP release was assessed in the organ bath fluid post-agonist-exposure. In dermal arteries, cinnamaldehyde- and capsaicin-induced relaxation remained unchanged after the aforementioned antagonists, while PregS-induced relaxation was significantly inhibited by isosakuranetin, L-NAME and MK-801. Furthermore, there was a significant increase in CGRP levels post-agonist-exposure. In our experimental model, TRPA1 and TRPV1 channels seem not to be involved in cinnamaldehyde- or capsaicin-induced relaxation, respectively, whereas TRPM3 channels contribute to PregS-induced relaxation, possibly via CGRP-independent mechanisms.

Serum uric acid predicts therapeutic response to midodrine hydrochloride in children with vasovagal syncope: a pilot study

Serum uric acid (UA) level has been proven to be related to several cardiovascular and metabolic diseases. In the present study, we examined if baseline serum UA level could predict the therapeutic efficacy of midodrine hydrochloride on vasovagal syncope (VVS) in children. The pediatric VVS patients who received midodrine hydrochloride from November 2008 to October 2022 were enrolled. After a median treatment duration of 3 months, the therapeutic effect was evaluated. According to the patients' responses to midodrine hydrochloride, which was determined by the recurrence of syncope, they were divided into effective and ineffective groups. The baseline variables were explored using univariable and multivariate logistic analysis. The predictive efficacy was assessed by receiver operating characteristic curve (ROC), precision-recall curve (PR), Hosmer-Lemeshow test, calibration curve, and decision curve analysis (DCA). Totally, 53 participants were included in the study. Among the 51 patients who were successfully followed up, 29 (56.9%) responded to midodrine hydrochloride (effective group), and the other 22 (43.1%) failed to respond to midodrine hydrochloride (ineffective group). The participants in effective group had lower baseline serum UA level than those in ineffective group (276.5 ± 73 μmol/L vs. 332.7 ± 56 μmol/L, p = 0.004). Multivariable logistic analysis showed that serum UA was associated with the therapeutic response (odds ratio (OR): 0.985, 95% confidence interval (CI): 0.974-0.997, p = 0.01). ROC analysis indicated that using baseline serum UA < 299 μmol/L as a threshold value yielded a sensitivity of 77.3% and a specificity of 79.3% in predicting the treatment response to midodrine hydrochloride. The area under the PR curve was 0.833. Hosmer-Lemeshow test yielded a p value of 0.58, and calibration plot indicated that the model was well-fitted. DCA demonstrated that treatment decision depending on the baseline serum UA level resulted in a favorable net benefit.   Conclusion: This pilot study suggested that the baseline serum UA level could be taken as a predictor of therapeutic effect of midodrine hydrochloride on VVS in children. What is Known: • Empirical and unselected use of midodrine hydrochloride has an unfavorable therapeutic effect on VVS in children. Serum uric acid (UA) is closely linked to cardiovascular events. What is New: • A low baseline serum UA level successfully predicts the therapeutic effectiveness of midodrine hydrochloride on VVS in children.

Calcitonin gene-related peptide protects from soluble fms-like tyrosine kinase-1-induced vascular dysfunction in a preeclampsia mouse model

Introduction: Preeclampsia (PE) is a hypertensive disorder during pregnancy associated with elevated levels of soluble FMS-like tyrosine kinase (sFLT-1) and increased vascular sensitivity to angiotensin II (ATII). Calcitonin gene-related peptide (CALCA) is a potent vasodilator that inhibits the ATII-induced increase in blood pressure and protects against ATII-induced increases in oxidative stress through a mitochondrial-dependent pathway in male mice. In rodent pregnancy, CALCA facilitates pregnancy-induced vascular adaptation. Most of the vascular effects of CALCA are mediated by vascular smooth muscle cells (VSMCs). We recently reported that CALCA treatment inhibits sFLT-1-induced decreases in cAMP synthesis in omental artery smooth muscle cells (OASMCs) isolated from pregnant women and has relaxant effects in omental arteries (OAs) isolated from pregnant women with preeclamptic (PE) pregnancies. The current study was designed to assess the effects of sFLT-1 on mitochondrial bioenergetics in OASMCs isolated from pregnant women in the presence or absence of CALCA and assess the development of vascular dysfunction in sFLT-1 using a mouse model of PE pregnancy. Methods: OASMCs were isolated from pregnant women to assess the effects of sFLT-1 on mitochondrial bioenergetics and oxidative stress using the Seahorse assay and quantitative PCR. Pregnant mice overexpressing sFLT-1 via adenoviral delivery were used to assess the effects of CALCA infusion on the sFLT-1-induced increase in blood pressure, ATII hypersensitivity, fetal growth restriction, and the elevated albumin-creatinine ratio. Systemic blood pressure was recorded in conscious, freely moving mice using implantable radio telemetry devices. Results: CALCA inhibited the following sFLT-1-induced effects: 1) increased oxidative stress and the decreased oxygen consumption rate (OCR) in response to maximal respiration and ATP synthesis; 2) increases in the expression of mitochondrial enzyme complexes in OASMCs; 3) increased mitochondrial fragmentation in OASMCs; 4) decreased expression of mitophagy-associated PINK1 and DRAM1 mRNA expression in OASMCs; and 5) increased blood pressure, ATII hypersensitivity, fetal growth restriction, and the albumin-creatinine ratio in sFLT-1-overexpressing pregnant mice. Conclusion: CALCA inhibits sFLT-1-induced alterations in mitochondrial bioenergetics in vascular smooth muscle cells and development of maternal vascular dysfunction in a mouse model of PE.

The vascular role of CGRP: a systematic review of human studies

Intravenous infusion of human alpha calcitonin gene-related peptide (h-α-CGRP) has been applied to explore migraine pathogenesis and cerebral hemodynamics during the past three decades. Cumulative data implicate h-α-CGRP in regulating the vascular tone. In this systematic review, we searched PubMed and EMBASE for clinical studies investigating the vascular changes upon intravenous infusion of h-α-CGRP in humans. A total of 386 studies were screened by title and abstract. Of these, 11 studies with 61 healthy participants and 177 participants diagnosed with migraine were included. Several studies reported hemodynamic effects including flushing, palpitation, warm sensation, heart rate (HR), mean arterial blood pressure (MABP), mean blood flow velocity of middle cerebral artery (mean V_MCA), and diameter of superficial temporal artery (STA). Upon the start of h-α-CGRP infusion, 163 of 165 (99%) participants had flushing, 98 of 155 (63%) participants reported palpitation, and 160 of 165 (97%) participants reported warm sensation. HR increased with 14%-58% and MABP decreased with 7%-12%. The mean V_MCA was decreased with 9.5%-21%, and the diameter of the STA was dilated with 41%-43%. The vascular changes lasted from 20 to >120 min. Intravenous infusion of h-α-CGRP caused a universal vasodilation without any serious adverse events. The involvement of CGRP in the systemic hemodynamic raises concerns regarding long-term blockade of CGRP in migraine patients with and without cardiovascular complications.

Calcitonin Gene-Related Peptide Monoclonal Antibodies and Risk of SARS-CoV-2 Infection and Severe COVID-19 Outcomes Among Veterans With Migraine Disorder

Importance

Calcitonin gene-related peptide (CGRP), a neuropeptide involved in migraine pathophysiology, is also a key neuroimmune modulator. CGRP antagonists may help mitigate the hyperinflammatory response observed in patients with COVID-19; however, findings from the literature are contradictory, and to date, no study has investigated the safety and effectiveness of CGRP antagonists against COVID-19.

Objective

To evaluate the association between CGRP monoclonal antibody (mAb) treatment and risk of SARS-CoV-2 infection and sequela hospitalization, requiring supplemental oxygen, use of mechanical ventilation, or death.

Design, Setting, and Participants

This retrospective cohort study analyzed the electronic health records of US veterans aged 18 to 65 years who were diagnosed with migraine disorder and were at risk of COVID-19 between January 20, 2020, and May 19, 2022.

Exposure

Initiation of CGRP mAbs.

Main Outcomes and Measures

The main outcome was cumulative incidence of SARS-CoV-2 infection. Odds of 30-day hospitalization, requiring supplemental oxygen, use of mechanical ventilation, or death were secondary outcomes.

Results

Among 8 178 652 eligible person-trials (354 294 veterans), 9992 (mean [SD] age, 46.0 [9.5] years; 53.9% male) initiated CGRP mAbs and 8 168 660 (mean [SD] age, 46.6 [10.2] years; 65.7% male) did not initiate CGRP mAbs. Over a 28-month follow-up period, 1247 initiators (12.5%) and 780 575 noninitiators (9.6%) tested positive for SARS-CoV-2. After censoring persons who deviated from treatment, the incidence was 7.4 cases per 1000 person-months among initiators and 6.9 per 1000 person-months among noninitiators. The inverse probability-weighted observational analogs of intention-to-treat and per-protocol hazard ratios were 0.95 (95% CI, 0.89-1.01) and 0.93 (95% CI, 0.86-1.02), respectively. No significant differences in the likelihood of hospitalization (odds ratio [OR], 0.93; 95% CI, 0.62-1.41), requiring supplemental oxygen (OR, 0.77; 95% CI, 0.45-1.30), use of mechanical ventilation (OR, 0.85; 95% CI, 0.26-2.84), or death (OR, 0.67; 95% CI, 0.09-5.23) were observed between CGRP mAb initiators and noninitiators who tested positive for SARS-CoV-2.

Conclusions and Relevance

In this cohort study, CGRP mAb treatment was not associated with positive SARS-CoV-2 test results or risk of severe COVID-19 outcomes, suggesting that CGRP mAbs may be used for migraine prevention during the COVID-19 pandemic. Given the few events of requiring supplemental oxygen, use of mechanical ventilation, and death, replication analysis in a larger sample of patients later in the course of disease is warranted.

Clinical Potential of Adrenomedullin Signaling in the Cardiovascular System

Numerous clinical studies have revealed the utility of circulating AM (adrenomedullin) or MR-proAM (mid-regional proAM 45-92) as an effective prognostic and diagnostic biomarker for a variety of cardiovascular-related pathophysiologies. Thus, there is strong supporting evidence encouraging the exploration of the AM-CLR (calcitonin receptor-like receptor) signaling pathway as a therapeutic target. This is further bolstered because several drugs targeting the shared CGRP (calcitonin gene-related peptide)-CLR pathway are already Food and Drug Administration-approved and on the market for the treatment of migraine. In this review, we summarize the AM-CLR signaling pathway and its modulatory mechanisms and provide an overview of the current understanding of the physiological and pathological roles of AM-CLR signaling and the yet untapped potentials of AM as a biomarker or therapeutic target in cardiac and vascular diseases and provide an outlook on the recently emerged strategies that may provide further boost to the possible clinical applications of AM signaling.

CGRP physiology, pharmacology, and therapeutic targets: migraine and beyond

Calcitonin gene-related peptide (CGRP) is a neuropeptide with diverse physiological functions. Its two isoforms (α and β) are widely expressed throughout the body in sensory neurons as well as in other cell types, such as motor neurons and neuroendocrine cells. CGRP acts via at least two G protein-coupled receptors that form unusual complexes with receptor activity-modifying proteins. These are the CGRP receptor and the AMY1 receptor; in rodents, additional receptors come into play. Although CGRP is known to produce many effects, the precise molecular identity of the receptor(s) that mediates CGRP effects is seldom clear. Despite the many enigmas still in CGRP biology, therapeutics that target the CGRP axis to treat or prevent migraine are a bench-to-bedside success story. This review provides a contextual background on the regulation and sites of CGRP expression and CGRP receptor pharmacology. The physiological actions of CGRP in the nervous system are discussed, along with updates on CGRP actions in the cardiovascular, pulmonary, gastrointestinal, immune, hematopoietic, and reproductive systems and metabolic effects of CGRP in muscle and adipose tissues. We cover how CGRP in these systems is associated with disease states, most notably migraine. In this context, we discuss how CGRP actions in both the peripheral and central nervous systems provide a basis for therapeutic targeting of CGRP in migraine. Finally, we highlight potentially fertile ground for the development of additional therapeutics and combinatorial strategies that could be designed to modulate CGRP signaling for migraine and other diseases.

Fasudil Ameliorates Osteoporosis Following Myocardial Infarction by Regulating Cardiac Calcitonin Secretion

We hypothesis that Rho kinase inhibitor fasudil ameliorates osteoporosis following myocardial infarction (MI) by regulating cardiac calcitonin secretion. A mice model of MI and cultured neonatal cardiomyocytes exposed to hypoxia and serum deprivation (H/SD), and fibroblasts exposed to TGF-β were used, respectively. Cardiac function in vivo was assessed with echocardiography. Osteoporosis in vivo was assessed with X-ray and micro-CT. In vivo and in vitro studies used histological and immunohistochemical techniques, along with western blots. In mice post-MI, fasudil ameliorates the microstructure and bone metabolism of the lumbar, improved cardiac function, and attenuated myocardial fibrosis. In vitro, fasudil or αCGRP could effectively inhibit the proliferation of primary fibroblasts treated with TGF-β. Moreover, fasudil ameliorates the cardiac calcitonin secretion induced by MI in vivo or by H/SD in vitro. Our findings suggest that fasudil improved MI-induced osteoporosis by promoting cardiac secreting calcitonin.

Sustained Activation of CLR/RAMP Receptors by Gel-Forming Agonists

Background: Adrenomedullin (ADM), adrenomedullin 2 (ADM2), and CGRP family peptides are important regulators of vascular vasotone and integrity, neurotransmission, and fetoplacental development. These peptides signal through CLR/RAMP1, 2, and 3 receptors, and protect against endothelial dysfunction in disease models. As such, CLR/RAMP receptor agonists are considered important therapeutic candidates for various diseases. Methods and Results: Based on the screening of a series of palmitoylated chimeric ADM/ADM2 analogs, we demonstrated a combination of lipidation and accommodating motifs at the hinge region of select peptides is important for gaining an enhanced receptor-activation activity and improved stimulatory effects on the proliferation and survival of human lymphatic endothelial cells when compared to wild-type peptides. In addition, by serendipity, we found that select palmitoylated analogs self-assemble to form liquid gels, and subcutaneous administration of an analog gel led to the sustained presence of the peptide in the circulation for >2 days. Consistently, subcutaneous injection of the analog gel significantly reduced the blood pressure in SHR rats and increased vasodilation in the hindlimbs of adult rats for days. Conclusions: Together, these data suggest gel-forming adrenomedullin analogs may represent promising candidates for the treatment of various life-threatening endothelial dysfunction-associated diseases such as treatment-resistant hypertension and preeclampsia, which are in urgent need of an effective drug.

Myocardial perfusion recovery induced by an α-calcitonin gene-related peptide analogue

BACKGROUND

Endogenous calcitonin gene-related peptide (CGRP) induces cardioprotective effects through coronary vasodilation. However, the systemic administration of CGRP induces peripheral vasodilation and positive chronotropic and inotropic effects. This study aims to examine the net effect on coronary perfusion of the systemically administered α-calcitonin gene-related peptide analogue, SAX, in rats during myocardial infarction.

METHODS

Forty Sprague-Dawley rats underwent myocardial infarction. Following left anterior descending artery occlusion, [99mTc]Tc-sestamibi was administered to determine the myocardial perfusion before treatment. Twenty minutes, 24 and 48 h after [99mTc]Tc-sestamibi injection, the rats were treated with either SAX or placebo. Final infarct size was determined three weeks later by [99mTc]Tc-sestamibi SPECT/CT scan.

RESULTS

Thirty-one rats survived the surgery and 20 completed the follow-up SPECT/CT scan (SAX n = 12; Placebo n = 8). At baseline, there was no difference in size of perfusion defect between the groups (P = .88), but at follow-up the SAX group had improved myocardial recovery compared to the placebo group (P = .04), corresponding to a relative perfusion recovery of 55% in SAX-treated rats.

CONCLUSION

The CGRP analogue, SAX, has a cardioprotective effect in this rat model of myocardial infarction, improving myocardial perfusion recovery after chronic occlusion of the coronary artery.

Perirenal adipose afferent nerves sustain pathological high blood pressure in rats

Hypertension is a pathological condition of persistent high blood pressure (BP) of which the underlying neural mechanisms remain obscure. Here, we show that the afferent nerves in perirenal adipose tissue (PRAT) contribute to maintain pathological high BP, without affecting physiological BP. Bilateral PRAT ablation or denervation leads to a long-term reduction of high BP in spontaneous hypertensive rats (SHR), but has no effect on normal BP in control rats. Further, gain- and loss-of-function and neuron transcriptomics studies show that augmented activities and remodeling of L1-L2 dorsal root ganglia neurons are responsible for hypertension in SHR. Moreover, we went on to show that calcitonin gene-related peptide (CGRP) is a key endogenous suppressor of hypertension that is sequestered by pro-hypertensive PRAT in SHRs. Taken together, we identify PRAT afferent nerves as a pro-hypertensive node that sustains high BP via suppressing CGRP, thereby providing a therapeutic target to tackle primary hypertension.

Capsaicin Prevents Contrast-Associated Acute Kidney Injury through Activation of Nrf2 in Mice

Capsaicin, a transient receptor potential vanilloid 1 channel agonist, possesses antioxidative properties through activating nuclear factor-erythroid 2-related factor 2 (Nrf2). As oxidative stress is a major contributor to the development of contrast-associated acute kidney injury (CA-AKI), we investigated the protective effect of capsaicin against CA-AKI via Nrf2. C57BL/6J mice were treated with dehydration and iodixanol to establish the model of CA-AKI. For pretreatment, capsaicin (0.3 mg/kg) was given via intraperitoneal injection one hour before iodixanol injection. Nrf2-specific siRNA was given through the tail vein to knock down Nrf2. The CA-AKI mouse model had remarkable mitochondrial fragmentation and dysfunction and apoptosis of tubular cells, overproduction of superoxide in renal tubules, increased renal malondialdehyde, tubular epithelial cell injury, and renal dysfunction. Importantly, pretreatment with capsaicin significantly ameliorated tubular cell injury and renal dysfunction with decreased superoxide, renal malondialdehyde, and apoptotic tubular cells and improved mitochondrial morphology and function in the CA-AKI mouse model. The expression of Nrf2 was increased in the kidney from the CA-AKI mouse model and was further enhanced by capsaicin. Administration of siRNA through the tail vein successfully decreased Nrf2 expression in the kidney, and knockdown of Nrf2 by siRNA abolished the beneficial effects of capsaicin on CA-AKI. The present study demonstrated a protective effect of capsaicin pretreatment against CA-AKI via Nrf2.

CGRP inhibits human Langerhans cells infection with HSV by differentially modulating specific HSV-1 and HSV-2 entry mechanisms

Herpes simplex virus (HSV) is widespread globally, with both HSV-1 and HSV-2 responsible for genital herpes. During sexual transmission, HSV targets epithelial cells, sensory peripheral pain neurons secreting the mucosal neuropeptide calcitonin gene-related peptide (CGRP), and mucosal immune cells including Langerhans cells (LCs). We previously described a neuro-immune crosstalk, whereby CGRP inhibits LCs-mediated human immunodeficiency virus type 1 (HIV-1) transmission. Herein, to further explore CGRP-mediated anti-viral function, we investigated whether CGRP affects LCs infection with HSV. We found that both HSV-1 and HSV-2 primary isolates productively infect monocyte-derived LCs (MDLCs) and inner foreskin LCs. Moreover, CGRP significantly inhibits infection with both HSV subtypes of MDLCs and langerin^high, but not langerin^low, inner foreskin LCs. For HSV-1, infection is mediated via the HSV-1-specific entry receptor 3-O sulfated heparan sulfate (3-OS HS) in a pH-depended manner, and CGRP down-regulates 3-OS HS surface expression, as well as abrogates pH dependency. For HSV-2, infection involves langerin-mediated endocytosis in a pH-independent manner, and CGRP up-regulates surface expression of atypical langerin double-trimer oligomers. Our results show that CGRP inhibits mucosal HSV infection by differentially modulating subtype-specific entry receptors and mechanisms in human LCs. CGRP could turn out useful for prevention of LCs-mediated HSV infection and HSV/HIV-1 co-infection.

The Neuropeptide α-Calcitonin Gene-Related Peptide as the Mediator of Beneficial Effects of Exercise in the Cardiovascular System

Regular physical activity exerts cardiovascular protective effects in healthy individuals and those with chronic cardiovascular diseases. Exercise is accompanied by an increased plasma concentration of α-calcitonin gene-related peptide (αCGRP), a 37-amino acid peptide with vasodilatory effects and causative roles in migraine. Moreover, mouse models revealed that loss of αCGRP disrupts physiological adaptation of the cardiovascular system to exercise in normotension and aggravates cardiovascular impairment in primary chronic hypertension, both can be reversed by αCGRP administration. This suggests that αCGRP agonists could be a therapeutic option to mediate the cardiovascular protective effects of exercise in clinical setting where exercise is not possible or contraindicated. Of note, FDA has recently approved αCGRP antagonists for migraine prophylaxis therapy, however, the cardiovascular safety of long-term anti-CGRP therapy in individuals with cardiovascular diseases has yet to be established. Current evidence from preclinical models suggests that chronic αCGRP antagonism may abolish the cardiovascular protective effects of exercise in both normotension and chronic hypertension.

Lipidated Calcitonin Gene-Related Peptide (CGRP) Peptide Antagonists Retain CGRP Receptor Activity and Attenuate CGRP Action In Vivo

Signaling through calcitonin gene-related peptide (CGRP) receptors is associated with pain, migraine, and energy expenditure. Small molecule and monoclonal antibody CGRP receptor antagonists that block endogenous CGRP action are in clinical use as anti-migraine therapies. By comparison, the potential utility of peptide antagonists has received less attention due to suboptimal pharmacokinetic properties. Lipidation is an established strategy to increase peptide half-life in vivo. This study aimed to explore the feasibility of developing lipidated CGRP peptide antagonists that retain receptor antagonist activity in vitro and attenuate endogenous CGRP action in vivo. CGRP peptide analogues based on the archetypal CGRP receptor antagonist, CGRP_8-37, were palmitoylated at the N-terminus, position 24, and near the C-terminus at position 35. The antagonist activities of the lipidated peptide analogues were tested in vitro using transfected Cos-7 cells expressing either the human or mouse CGRP receptor, amylin subtype 1 (AMY₁) receptor, adrenomedullin (AM) receptors, or calcitonin receptor. Antagonist activities were also evaluated in SK-N-MC cells that endogenously express the human CGRP receptor. Lipidated peptides were then tested for their ability to antagonize endogenous CGRP action in vivo using a capsaicin-induced dermal vasodilation (CIDV) model in C57/BL6J mice. All lipidated peptides except for the C-terminally modified analogue retained potent antagonist activity compared to CGRP_8-37 towards the CGRP receptor. The lipidated peptides also retained, and sometimes gained, antagonist activities at AMY₁, AM₁ and AM₂ receptors. Several lipidated peptides produced robust inhibition of CIDV in mice. This study demonstrates that selected lipidated peptide antagonists based on αCGRP_8-37 retain potent antagonist activity at the CGRP receptor and are capable of inhibition of endogenous CGRP action in vivo. These findings suggest that lipidation can be applied to peptide antagonists, such as αCGRP_8-37 and are a potential strategy for antagonizing CGRP action.

The Vascular-Dependent and -Independent Actions of Calcitonin Gene-Related Peptide in Cardiovascular Disease

The treatment of hypertension and heart failure remains a major challenge to healthcare providers. Despite therapeutic advances, heart failure affects more than 26 million people worldwide and is increasing in prevalence due to an ageing population. Similarly, despite an improvement in blood pressure management, largely due to pharmacological interventions, hypertension remains a silent killer. This is in part due to its ability to contribute to heart failure. Development of novel therapies will likely be at the forefront of future cardiovascular studies to address these unmet needs. Calcitonin gene-related peptide (CGRP) is a 37 amino acid potent vasodilator with positive-ionotropic and -chronotropic effects. It has been reported to have beneficial effects in hypertensive and heart failure patients. Interestingly, changes in plasma CGRP concentration in patients after myocardial infarction, heart failure, and in some forms of hypertension, also support a role for CGRP on hemodynamic functions. Rodent studies have played an important role thus far in delineating mechanisms involved in CGRP-induced cardioprotection. However, due to the short plasma half-life of CGRP, these well documented beneficial effects have often proven to be acute and transient. Recent development of longer lasting CGRP agonists may therefore offer a practical solution to investigating CGRP further in cardiovascular disease in vivo. Furthermore, pre-clinical murine studies have hinted at the prospect of cardioprotective mechanisms of CGRP which is independent of its hypotensive effect. Here, we discuss past and present evidence of vascular-dependent and -independent processes by which CGRP could protect the vasculature and myocardium against cardiovascular dysfunction.

Alpha-Calcitonin Gene Related Peptide: New Therapeutic Strategies for the Treatment and Prevention of Cardiovascular Disease and Migraine

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.

Native CGRP Neuropeptide and Its Stable Analogue SAX, But Not CGRP Peptide Fragments, Inhibit Mucosal HIV-1 Transmission

Background

The vasodilator neuropeptide calcitonin gene-related peptide (CGRP) plays both detrimental and protective roles in different pathologies. CGRP is also an essential component of the neuro-immune dialogue between nociceptors and mucosal immune cells. We previously discovered that CGRP is endowed with anti-viral activity and strongly inhibits human immunodeficiency virus type 1 (HIV-1) infection, by suppressing Langerhans cells (LCs)-mediated HIV-1 trans-infection in-vitro and mucosal HIV-1 transmission ex-vivo. This inhibition is mediated via activation of the CGRP receptor non-canonical NFκB/STAT4 signaling pathway that induces a variety of cooperative mechanisms. These include CGRP-mediated increase in the expression of the LC-specific pathogen recognition C-type lectin langerin and decrease in LC-T-cell conjugates formation. The clinical utility of CGRP and modalities of CGRP receptor activation, for inhibition of mucosal HIV-1 transmission, remain elusive.

Methods

We tested the capacity of CGRP to inhibit HIV-1 infection in-vivo in humanized mice. We further compared the anti-HIV-1 activities of full-length native CGRP, its metabolically stable analogue SAX, and several CGRP peptide fragments containing its binding C-terminal and activating N-terminal regions. These agonists were evaluated for their capacity to inhibit LCs-mediated HIV-1 trans-infection in-vitro and mucosal HIV-1 transmission in human mucosal tissues ex-vivo.

Results

A single CGRP intravaginal topical treatment of humanized mice, followed by HIV-1 vaginal challenge, transiently restricts the increase in HIV-1 plasma viral loads but maintains long-lasting higher CD4+ T-cell counts. Similarly to CGRP, SAX inhibits LCs-mediated HIV-1 trans-infection in-vitro, but with lower potency. This inhibition is mediated via CGRP receptor activation, leading to increased expression of both langerin and STAT4 in LCs. In contrast, several N-terminal and N+C-terminal bivalent CGRP peptide fragments fail to increase langerin and STAT4, and accordingly lack anti-HIV-1 activities. Finally, like CGRP, treatment of human inner foreskin tissue explants with SAX, followed by polarized inoculation with cell-associated HIV-1, completely blocks formation of LC-T-cell conjugates and HIV-1 infection of T-cells.

Conclusion

Our results show that CGRP receptor activation by full-length CGRP or SAX is required for efficient inhibition of LCs-mediated mucosal HIV-1 transmission. These findings suggest that formulations containing CGRP, SAX and/or their optimized agonists/analogues could be harnessed for HIV-1 prevention.

Vascular smooth muscle cell-specific miRNA-214 knockout inhibits angiotensin II-induced hypertension through upregulation of Smad7

Vascular remodeling is a prominent trait during the development of hypertension, attributable to the phenotypic transition of vascular smooth muscle cells (VSMCs). Increasing studies demonstrate that microRNA plays an important role in this process. Here, we surprisingly found that smooth muscle cell-specific miR-214 knockout (miR-214 cKO) significantly alleviates angiotensin II (Ang II)-induced hypertension, which has the same effect as that of miR-214 global knockout mice in response to Ang II stimulation. Under the treatment of Ang II, miR-214 cKO mice exhibit substantially reduced systolic blood pressure. The vascular medial thickness and area in miR-214 cKO blood vessels were obviously reduced, the expression of collagen I and proinflammatory factors were also inhibited. VSMC-specific deletion of miR-214 blunts the response of blood vessels to the stimulation of endothelium-dependent and -independent vasorelaxation and phenylephrine and 5-HT induced vasocontraction. In vitro, Ang II-induced VSMC proliferation, migration, contraction, hypertrophy, and stiffness were all repressed with miR-214 KO in VSMC. To further explore the mechanism of miR-214 in the regulation of the VSMC function, it is very interesting to find that the TGF-β signaling pathway is mostly enriched in miR-214 KO VSMC. Smad7, the potent negative regulator of the TGF-β/Smad pathway, is identified to be the target of miR-214 in VSMC. By which, miR-214 KO sharply enhances Smad7 levels and decreases the phosphorylation of Smad3, and accordingly alleviates the downstream gene expression. Further, Ang II-induced hypertension and vascular dysfunction were reversed by antagomir-214. These results indicate that miR-214 in VSMC established a crosstalk between Ang II-induced AT1R signaling and TGF-β induced TβRI /Smad signaling, by which it exerts a pivotal role in vascular remodeling and hypertension and imply that miR-214 has the potential as a therapeutic target for the treatment of hypertension.

Exploring Ligand Binding to Calcitonin Gene-Related Peptide Receptors

Class B1 G protein-coupled receptors (GPCRs) are important targets for many diseases, including cancer, diabetes, and heart disease. All the approved drugs for this receptor family are peptides that mimic the endogenous activating hormones. An understanding of how agonists bind and activate class B1 GPCRs is fundamental for the development of therapeutic small molecules. We combined supervised molecular dynamics (SuMD) and classic molecular dynamics (cMD) simulations to study the binding of the calcitonin gene-related peptide (CGRP) to the CGRP receptor (CGRPR). We also evaluated the association and dissociation of the antagonist telcagepant from the extracellular domain (ECD) of CGRPR and the water network perturbation upon binding. This study, which represents the first example of dynamic docking of a class B1 GPCR peptide, delivers insights on several aspects of ligand binding to CGRPR, expanding understanding of the role of the ECD and the receptor-activity modifying protein 1 (RAMP1) on agonist selectivity.

The effects of sacubitril/valsartan on heart failure with preserved ejection fraction: a meta-analysis

BACKGROUND

Compared with angiotensin-converting enzyme inhibitors and angiotensin receptor blockers, Sacubitril/Valsartan has been reported to have superior results. However, the effects of sacubitril/valsartan on heart failure with preserved ejection fraction (HFpEF) are still in dispute.

OBJECTIVES

This study aims to evaluate the effects of sacubitril/valsartan on the treatment of HFpEF patients.

METHODS

PubMed, Embase, Web of Science, Cochrane Library, and Clinicaltrials.gov were used to search for randomised controlled trials of sacubitril/valsartan in HFpEF patients from inception to 7 December 2020.

RESULTS

Four studies, with a total of 7739 participants, met the inclusion criteria. The present meta-analysis results showed that compared with the control group, sacubitril/valsartan reduced the hospitalisation rate of HF in HFpEF patients [Risk Ratio(RR): 0.85; 95% confidence interval (CI): 0.79-0.93; p = 0.0002). Regarding all-cause mortality, cardiovascular mortality, and the improvement in NYHA class, sacubitril/valsartan did not show apparent advantages. Although sacubitril/valsartan was linked to increasing the risk of symptomatic hypotension (RR: 1.44; 95% CI: 1.25-1.66; p﹤0.00001), there was no evidence supporting the incidence of renal function worsening and hyperkalemia.

CONCLUSION

Our study shows that compared with valsartan or individualised medical therapy (IMT), there were not different between the two groups except for the hospitalisation rate which was favoured by Sacubitril/Valsartan treatment group for HFpEF patients.

Network meta-analysis on efficacy and safety of different anti-CGRP monoclonal antibody regimens for prophylaxis and treatment of episodic migraine

BACKGROUND

Currently, studies have shown that anti-CGRP monoclonal antibodies are effective drugs for the prophylaxis and treatment of episodic migraine. Therefore, for the first time, we classified and concluded 10 treatment regimens according to the different doses, drugs, routes of administration, and courses of treatment, so as to provide a reference for further clinical studies.

METHODS

We studied relevant randomized controlled trials (RCTs) published before August 2020 on PubMed, Embase, Ovid MEDLINE, Web of Science, and the Cochrane Central Register of Controlled Trials.

RESULTS

Eleven RCTs involving 6397 patients were included in our analysis. Network meta-analysis results suggested that in the comparison of the average migraine days per month, Erenumab  (140 mg), Galcanezumab (120 mg, 240 mg), Fremanezumab (225 mg, 675 mg) were superior to placebo, Erenumab(7 mg), and the difference was statistically significant; Fremanezumab (225 mg, 675 mg) was superior to Erenumab (21 mg, 70 mg), and the difference was statistically significant; in the comparison of average medication days of acute migraine-specific drug per month, Erenumab (70 mg, 140 mg), Galcanezumab (120 mg, 240 mg), Fremanezumab (225 mg, 675 mg) was superior to placebo, and Erenumab (140 mg) and Galcanezumab (120 mg, 240 mg) were superior to Erenumab (70 mg), and the difference was statistically significant; there was no statistically significant difference in the average migraine days in the last month or in the medication days of acute migraine-specific drug.

CONCLUSION

Fremanezumab (225 mg) and Galcanezumab (120 mg) may be the best clinical protocol after a comprehensive assessment.

The PLGA nanoparticles for sustainable release of CGRP to ameliorate the inflammatory and vascular disorders in the lung of CGRP-deficient rats

The calcitonin gene-related peptide (CGRP) has been demonstrated relating to vascular and inflammatory regulations not only the nerve systems. As the anti-inflammation factor and the most potent vasodilator, the CGRP holds therapeutic potentials for the treatment of cardiovascular diseases which was, however, limited by its peptide nature and short half-life. With advantages in improving the stability, circulation time and protection from degradation, the nanoparticles were promising as delivery carriers for the peptide. Nevertheless, few nanoparticulate systems were developed to deliver the CGRP peptide for the modulation of vascular or inflammatory functions instead of neural regulation. In this study, the CGRP was encapsulated into the poly (lactic-co-glycolic acid) (PLGA) nanoparticle for sustained release of CGRP in vivo. The nanoparticles recovered the systemic level of CGRP and the vascular inflammatory factors in the CGRP^+/− rats comparing to the administration of (Dulbecco's Phosphate Buffered Saline) DPBS or peptide only. With the decrease of vascular wall thickness and the attenuation of the T cell infiltration in the lung, the polymer based CGRP delivery system showed potentials to facilitate the therapeutic effects of the CGRP which may help for the development of CGRP-based therapy in vascular and inflammatory disorder related diseases.

Oxidative stress in cardiac hypertrophy: From molecular mechanisms to novel therapeutic targets

When faced with increased workload the heart undergoes remodelling, where it increases its muscle mass in an attempt to preserve normal function. This is referred to as cardiac hypertrophy and if sustained, can lead to impaired contractile function. Experimental evidence supports oxidative stress as a critical inducer of both genetic and acquired forms of cardiac hypertrophy, a finding which is reinforced by elevated levels of circulating oxidative stress markers in patients with cardiac hypertrophy. These observations formed the basis for using antioxidants as a therapeutic means to attenuate cardiac hypertrophy and improve clinical outcomes. However, the use of antioxidant therapies in the clinical setting has been associated with inconsistent results, despite antioxidants having been shown to exert protection in several animal models of cardiac hypertrophy. This has forced us to revaluate the mechanisms, both upstream and downstream of oxidative stress, where recent studies demonstrate that apart from conventional mediators of oxidative stress, metabolic disturbances, mitochondrial dysfunction and inflammation as well as dysregulated autophagy and protein homeostasis contribute to disease pathophysiology through mechanisms involving oxidative stress. Importantly, novel therapeutic targets have been identified to counteract oxidative stress and attenuate cardiac hypertrophy but more interestingly, the repurposing of drugs commonly used to treat metabolic disorders, hypertension, peripheral vascular disease, sleep disorders and arthritis have also been shown to improve cardiac function through suppression of oxidative stress. Here, we review the latest literature on these novel mechanisms and intervention strategies with the aim of better understanding the complexities of oxidative stress for more precise targeted therapeutic approaches to prevent cardiac hypertrophy.

Calcitonin Gene-Related Peptide Protects Against Cardiovascular Dysfunction Independently of Nitric Oxide In Vivo

[Figure: see text].

Soluble fms-like tyrosine kinase-1 and angiotensin2 target calcitonin gene-related peptide family peptides in maternal vascular smooth muscle cells in pregnancy†

Calcitonin gene-related peptide (CALCB), adrenomedullin (ADM), and adrenomedullin2 (ADM2) are hypotensive peptides that belong to CALCB family of peptides. Goal of this study was to identify the effect of fms-like tyrosine kinase (sFLT-1) and angiotensin2 (Ang2) on the function of these peptides in OA smooth muscle cells (OASMC) and assess the sensitivity of OA for these peptides in preeclampsia (PE) and normotensive pregnancy.

METHODS

Peptide function was assessed by Cyclic adenosine monophosphate (cAMP) assays and wire myograph; mRNA expression by Polymerase chain reaction (PCR) and protein-protein interaction by proximity ligation assay and co-immunoprecipitation.

FINDINGS

All three peptides increased cAMP synthesis in the order of efficacy CALCB > ADM = ADM2 and vascular endothelial growth factor (VEGF) mRNA in OASMC (P < 0.05); sFLT-1 mediated decrease in cAMP synthesis (P < 0.05) is differentially rescued by all three CALCB family peptides in OASMC (P < 0.005); sFLT-1 decreased receptor activity-modifying protein (RAMP)1 and RAMP2 mRNA expression (P < 0.05); Ang2 decreased the expression of calcitonin-receptor-like receptor and RAMP1 mRNA and desensitized CALCB and ADM2 receptors in OASMC (P < 0.05); sFLT-1 increased RAMP1and Ang2 type 1 receptor (AT1R) interaction in OASMC which is inhibited in presence of all three peptides; and all three peptides relax OA in PE with enhanced ADM2 response (P < 0.05).

CONCLUSION

sFLT-1 and Ang2 impair OASMC mediated functional responses of CALCB family peptides which can be inhibited by respective peptide treatment. The sensitivity of OA for CALCB, ADM, and ADM2-mediated relaxation is retained in PE.

A Novel Alginate-Based Delivery System for the Prevention and Treatment of Pressure-Overload Induced Heart Failure

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.

Circulating Levels of Calcitonin Gene-Related Peptide Are Lower in COVID-19 Patients

Background

To better understand the biology of COVID-19, we have explored the behavior of calcitonin gene-related peptide (CGRP), an angiogenic, vasodilating, and immune modulating peptide, in severe acute respiratory syndrome coronavirus 2 positive patients.

Methods

Levels of CGRP in the serum of 57 COVID-19 patients (24 asymptomatic, 23 hospitalized in the general ward, and 10 admitted to the intensive care unit) and healthy donors (n = 24) were measured by enzyme-linked immunosorbent assay (ELISA). In addition, to better understand the physiological consequences of the observed variations, we investigated by immunofluorescence the distribution of receptor activity modifying protein 1 (RAMP1), one of the components of the CGRP receptor, in autopsy lung specimens.

Results

CGRP levels were greatly decreased in COVID-19 patients (P < 0.001) when compared to controls, and there were no significant differences due to disease severity, sex, age, or comorbidities. We found that COVID-19 patients treated with proton pump inhibitors had lower levels of CGRP than other patients not taking this treatment (P = 0.001). RAMP1 immunoreactivity was found in smooth muscle cells of large blood vessels and the bronchial tree and in the airways´ epithelium. In COVID-19 samples, RAMP1 was also found in proliferating type II pneumocytes, a common finding in these patients.

Conclusions

The lower levels of CGRP should negatively impact the respiratory physiology of COVID-19 patients due to vasoconstriction, improper angiogenesis, less epithelial repair, and faulty immune response. Therefore, restoring CGRP levels in these patients may represent a novel therapeutic approach for COVID-19.

CGRP Receptor Antagonism in COVID-19: Potential Cardiopulmonary Adverse Effects

Recently, the US FDA has authorized a drug repurposing trial with calcitonin gene-related peptide (CGRP) receptor antagonists to reduce lung inflammation in coronavirus 2019 (COVID-19). However, the well-established cardiopulmonary protective effects of CGRP raise concerns about the safety of antagonizing CGRP in COVID-19. Awareness regarding potential cardiopulmonary adverse effects may enable their early detection and prevent illness from worsening.

The Effects of Calcitonin Gene-Related Peptide on Bone Homeostasis and Regeneration

PURPOSE OF REVIEW

The goals of this review are two folds: (1) to describe the recent understandings on the roles of calcitonin gene-related peptide-α (CGRP) in bone homeostasis and the underlying mechanisms of related neuronal regulation and (2) to propose innovative CGRP-modulated approaches for enhancing bone regeneration in challenging bone disorders.

RECENT FINDINGS

CGRP is predominantly produced by the densely distributed sensory neuronal fibers in bone, declining with age. Under mechanical and biochemical stimulations, CGRP releases and exerts either physiological or pathophysiological roles. CGRP at physiological level orchestrates the communications of bone cells with cells of other lineages, affecting not only osteogenesis, osteoclastogenesis, and adipogenesis but also angiogenesis, demonstrating with pronounced anabolic effect, thus is essential for maintaining bone homeostasis, with tuned nerve-vessel-bone network. In addition, its effects on immunity and cell recruitment are also crucial for bone fracture healing. Binding to the G protein-coupled receptor composited by calcitonin receptor-like receptor (CRLR) and receptor activity modifying protein 1 (RAMP1) on cellular surface, CGRP triggers various intracellular signaling cascades involving cyclic adenosine monophosphate (cAMP) and cAMP response element-binding protein (CREB). Peaking at early stage post-fracture, CGRP promotes bone formation, displaying with larger callus. Then CGRP gradually decreases over time, allowing normal or physiological bone remodeling. By elevating CGRP at early stage, low-intensity pulsed ultrasound (LIPUS), electrical stimulation, and magnesium-based bio-mineral products may promisingly accelerate bone regeneration experimentally in medical conditions like osteoporosis, osteoporotic fracture, and spine fusion. Excess CGRP expression is commonly observed in pathological conditions including cancer metastatic lesions in bone and fracture delayed- or non-healing, resulting in persistent chronic pain. To date, these discoveries have largely been limited to animal models. Clinical applications are highly desirable. Compelling evidence show the anabolic effects of CGRP on bone in animals. However, further validation on the role of CGRP and the underlying mechanisms in human skeletons is required. It remains unclear if it is type H vessel connecting neuronal CGRP to osteogenesis, and if there is only specific rather than all osteoprogenitors responsible to CGRP. Clear priority should be put to eliminate these knowledge gaps by integrating with high-resolution 3D imaging of transparent bulk bone and single-cell RNA-sequencing. Last but not the least, given that small molecule antagonists such as BIBN4096BS can block the beneficial effects of CGRP on bone, concerns on the potential side effects of humanized CGRP-neutralizing antibodies when systemically administrated to treat migraine in clinics are arising.

Involvement of TRPV1-containing peripheral sensory efferents in hemodynamic responses in a rat hemorrhagic shock model

BACKGROUND

Mechanisms underlying hemodynamic disturbance in hemorrhagic shock are not completely understood. Transient receptor potential vanilloid 1-expressing afferents are involved in hemorrhagic shock pathology, and transient receptor potential vanilloid 1 antagonist, capsazepine, acts on the central nervous system to improve mortality in a rat hemorrhagic shock model. In contrast, transient receptor potential vanilloid 1-positive efferents promote vasoactive reactions through the release of neuropeptides, including calcitonin gene-related peptides. This study aimed to investigate whether transient receptor potential vanilloid 1-positive peripheral sensory efferents are involved in hemodynamic responses after hemorrhagic shock.

METHODS

Male rats underwent hemorrhagic shock (mean arterial pressure 30 mm Hg for 90 min, followed by resuscitation for 30 min) and received capsazepine (5 μM/kg) 30 min after shock induction. A separate cohort of rats subjected to hemorrhagic shock received hCGRP_8-37 (300 μg/kg), a calcitonin gene-related peptide receptor antagonist, at 30, 60, or 90 minutes after shock induction. The 24-hour survival rate, mean arterial pressure, heart rate, arterial blood gas, and plasma calcitonin gene-related peptide levels were measured. Tissue blood flow and oxygenation both in the mesentery and skeletal muscle were also assessed.

RESULTS

Capsazepine treatment prevented the hemorrhagic shock-induced increase in plasma calcitonin gene-related peptide levels, and hCGRP_8-37 treatment improved the 24-h survival rates after hemorrhagic shock at a time-dependent manner. The hCGRP_8-37- or capsazepine-treated rats exhibited tissue oxygenation and metabolic conditions comparable to those in control rats at the end of the experiment.

CONCLUSION

Transient receptor potential vanilloid 1 plays a crucial role in hemodynamic responses to hemorrhagic shock, partly via calcitonin gene-related peptide release, involved in its peripheral sensory-efferent functions. The hCGRP_8-37 appears to improve peripheral circulatory failure, which may be useful as adjunct treatment after hemorrhagic shock.

Alpha-calcitonin gene-related peptide prevents pressure-overload induced heart failure: role of apoptosis and oxidative stress

Alpha-calcitonin gene-related peptide (α-CGRP) is a 37-amino acid neuropeptide that plays an important protective role in modulating cardiovascular diseases. Deletion of the α-CGRP gene increases the vulnerability of the heart to pressure-induced heart failure and the administration of a modified α-CGRP agonist decreases this vulnerability. Systemic administration of α-CGRP decreases blood pressure in normotensive and hypertensive animals and humans. Here we examined the protective effect of long-term administration of native α-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 α-CGRP content, and increased hypertrophy, dilation, and fibrosis compared to sham mice. Administration of α-CGRP-filled mini-osmotic pumps (4 mg/kg bwt/day) in TAC mice preserved cardiac function and LV α-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 α-CGRP administration. α-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 α-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, α-CGRP is a potential therapeutic agent in preventing the progression to heart failure, and the cardio-protective action of α-CGRP is likely the result of a direct cellular effect; however, a partial vasodilatory blood pressure-dependent mechanism of α-CGRP cannot be excluded.

The neuropeptide calcitonin gene-related peptide alpha is essential for bone healing

Background

Impaired fracture healing represents an ongoing clinical challenge, as treatment options remain limited. Calcitonin gene-related peptide (CGRP), a neuropeptide targeted by emerging anti-migraine drugs, is also expressed in sensory nerve fibres innervating bone tissue.

Method

Bone healing following a femoral osteotomy stabilized with an external fixator was analysed over 21 days in αCGRP-deficient and WT mice. Bone regeneration was evaluated by serum analysis, µCT analysis, histomorphometry and genome-wide expression analysis. Bone-marrow-derived osteoblasts and osteoclasts, as well as the CGRP antagonist olcegepant were employed for mechanistic studies.

Findings

WT mice with a femoral fracture display increased CGRP serum levels. αCGRP mRNA expression after skeletal injury is exclusively induced in callus tissue, but not in other organs. On protein level, CGRP and its receptor, calcitonin receptor-like receptor (CRLR) complexing with RAMP1, are differentially expressed in the callus during bone regeneration. On the other hand, αCGRP-deficient mice display profoundly impaired bone regeneration characterised by a striking reduction in the number of bone-forming osteoblasts and a high rate of incomplete callus bridging and non-union. As assessed by genome-wide expression analysis, CGRP induces the expression of specific genes linked to ossification, bone remodeling and adipogenesis. This suggests that CGRP receptor-dependent PPARγ signaling plays a central role in fracture healing.

Interpretation

This study demonstrates an essential role of αCGRP in orchestrating callus formation and identifies CGRP receptor agonism as a potential approach to stimulate bone regeneration. Moreover, as novel agents blocking CGRP or its receptor CRLR are currently introduced clinically for the treatment of migraine disorders, their potential negative impact on bone regeneration warrants clinical investigation.

Funding

This work was funded by grants from the Else-Kröner-Fresenius-Stiftung (EKFS), the Deutsche Forschungsgemeinschaft (DFG), and the Berlin Institute of Health (BIH).

Picomolar Affinity Antagonist and Sustained Signaling Agonist Peptide Ligands for the Adrenomedullin and Calcitonin Gene-Related Peptide Receptors

The calcitonin receptor-like class B G protein-coupled receptor (CLR) mediates adrenomedullin (AM) and calcitonin gene-related peptide (CGRP) functions including vasodilation, cardioprotection, and nociception. Receptor activity-modifying proteins (RAMP1-3) form heterodimers with CLR and determine its peptide ligand selectivity through an unresolved mechanism. The CGRP (RAMP1:CLR) and AM (RAMP2/3:CLR) receptors are proven or promising drug targets, but short AM and CGRP plasma half-lives limit their therapeutic utility. Here, we used synthetic peptide combinatorial library and rational design approaches to probe the ligand selectivity determinants and develop truncated AM and CGRP antagonist variants with receptor extracellular domain binding affinities that were enhanced ∼1000-fold into the low nanomolar range. Receptor binding studies and a high-resolution crystal structure of a novel library-identified AM variant bound to the RAMP2-CLR extracellular domain complex explained the increased affinities and defined roles for AM Lys46 and RAMP modulation of CLR conformation in the ligand selectivity mechanism. In longer AM and CGRP scaffolds that also bind the CLR transmembrane domain, the variants generated picomolar affinity antagonists, one with an estimated 12.5 h CGRP receptor residence time, and sustained signaling agonists "ss-AM" and "ss-CGRP" that exhibited persistent cAMP signaling after ligand washout. Sustained signaling was demonstrated in primary human umbilical vein endothelial cells and the SK-N-MC cell line, which endogenously express AM and CGRP receptors, respectively. This work clarifies the RAMP-modulated CLR ligand selectivity mechanism and provides AM and CGRP variants that are valuable pharmacological tools and may have potential as long-acting therapeutics.

Pharmacological treatment of migraine: CGRP and 5-HT beyond the triptans

Migraine is a highly disabling neurovascular disorder characterized by a severe headache (associated with nausea, photophobia and/or phonophobia), and trigeminovascular system activation involving the release of calcitonin-gene related peptide (CGRP). Novel anti-migraine drugs target CGRP signaling through either stimulation of 5-HT1F receptors on trigeminovascular nerves (resulting in inhibition of CGRP release) or direct blockade of CGRP or its receptor. Lasmiditan is a highly selective 5-HT1F receptor agonist and, unlike the triptans, is devoid of vasoconstrictive properties, allowing its use in patients with cardiovascular risk. Since lasmiditan can actively penetrate the blood-brain barrier, central therapeutic as well as side effects mediated by 5-HT1F receptor activation should be further investigated. Other novel anti-migraine drugs target CGRP signaling directly. This neuropeptide can be targeted by the monoclonal antibodies eptinezumab, fremanezumab and galcanezumab, or by CGRP-neutralizing L-aptamers called Spiegelmers. The CGRP receptor can be targeted by the monoclonal antibody erenumab, or by small-molecule antagonists called gepants. Currently, rimegepant and ubrogepant have been developed for acute migraine treatment, while atogepant is studied for migraine prophylaxis. Of these drugs targeting CGRP signaling directly, eptinezumab, erenumab, fremanezumab, galcanezumab, rimegepant and ubrogepant have been approved for clinical use, while atogepant is in the last stage before approval. Although all of these drugs seem highly promising for migraine treatment, their safety should be investigated in the long-term. Moreover, the exact mechanism(s) of action of these drugs need to be elucidated further, to increase both safety and efficacy and to increase the number of responders to the different treatments, so that all migraine patients can satisfactorily be treated.

The Release of Cyclophilin A from Rapamycin-Stimulated Vascular Smooth Muscle Cells Mediated by Myosin II Activation: Involvement of Apoptosis but Not Autophagy

INTRODUCTION

The exocytosis of cyclophilin A (CyPA) by a vesicular pathway in response to reactive oxygen species has been determined. However, other sources of extracellular CyPA remain obscure.

OBJECTIVE

The aim of this study was to determine the role of autophagy in the secretion of CyPA.

METHODS AND RESULTS

Rapamycin induced the activation of autophagy and release of CyPA from primary cultured rat aortic smooth muscle cells (RASMCs). However, inhibition of autophagy by knockdown of Atg7 or chloroquine did not affect the rapamycin-induced release of CyPA. With the exception of myosin II activity, rho-associated coiled-coil kinase (ROCK), actin remodelling, and synaptic vesicles were not implicated in the release of rapamycin-induced CyPA. Finally, we confirmed that rapamycin-induced extracellular CyPA originated from apoptotic RASMCs. Furthermore, the decreased activation of myosin II by blebbistatin blocked the release of CyPA from apoptotic RASMCs induced by rapamycin.

CONCLUSIONS

Rapamycin induced the release of CyPA from apoptotic RASMCs but did not affect exocytosis through autophagosomes. ROCK, actin remodelling, and synaptic vesicles were not involved in the apoptosis-related release of CyPA. Myosin II activation modulated the apoptosis of vascular smooth muscle cells and the release of CyPA from rapamycin-induced apoptotic cell death.

Intermedin alleviates pathological cardiac remodeling by upregulating klotho

Cardiac remodeling is accompanied by cardiac hypertrophy, fibrosis, dysfunction, and eventually leading to heart failure. Intermedin (IMD), as a paracrine/autocrine peptide, has a protective effect in cardiovascular diseases. In this study, we elucidated the role and the underlying mechanism of IMD in pathological remodeling. Pathological remodeling mouse models were induced by abdominal aorta constriction for 4 weeks or angiotensin II (Ang II) infusion for 2 weeks in wildtype, IMD-overexpression, IMD-knockout and klotho-knockdown mice. Western blot, real-time PCR, histological staining, echocardiography and hemodynamics were used to detect the role of IMD in cardiac remodeling. Cardiac hypertrophy, fibrosis and dysfunction were significantly aggravated in IMD-knockout mice versus wildtype mice, and the expression of klotho was downregulated. Conversely, cardiac remodeling was alleviated in IMD-overexpression mice, and the expression of klotho was upregulated. Hypertension induced by Ang II infusion rather than abdominal aorta constriction was mitigated by IMD. However, the cardioprotective effect of IMD was blocked in klotho-knockdown mice. Similar results were found in cultured neonatal rat cardiomyocytes, which was pretreated with IMD before Ang II stimulation. Mechanistically, IMD inhibited the phosphorylation of Ca²⁺/calmodulin-dependent protein kinase II (CaMKII) and the activity of calcineurin to protect against cardiac hypertrophy through upregulating klotho in vivo and in vitro. Furthermore, peroxisome proliferator-activated receptor γ (PPARγ) might mediate IMD upregulating klotho. In conclusion, pathological remodeling may be alleviated by endogenous IMD, which inhibits the expression of calcineurin and p-CaMKII by upregulating klotho via the PPARγ pathway. It suggested that IMD might be a therapeutic target for heart disease.

The effects of CGRP in vascular tissue - Classical vasodilation, shadowed effects and systemic dilemmas

Vascular tissue consists of endothelial cells, vasoactive smooth muscle cells and perivascular nerves. The perivascular sensory neuropeptide CGRP has demonstrated potent vasodilatory effects in any arterial vasculature examined so far, and a local protective CGRP-circuit of sensory nerve terminal CGRP release and smooth muscle cell CGRP action is evident. The significant vasodilatory effect has shadowed multiple other effects of CGRP in the vascular tissue and we therefore thoroughly review vascular actions of CGRP on endothelial cells, vascular smooth muscle cells and perivascular nerve terminals. The actions beyond vasodilation includes neuronal re-uptake and neuromodulation, angiogenic, proliferative and antiproliferative, pro- and anti-inflammatory actions which vary depending on the target cell and anatomical location. In addition to the classical perivascular nerve-smooth muscle CGRP circuit, we review existing evidence for a shadowed endothelial autocrine pathway for CGRP. Finally, we discuss the impact of local and systemic actions of CGRP in vascular regulation and protection from hypertensive and ischemic heart conditions with special focus on therapeutic CGRP agonists and antagonists.

Calcitonin gene-related peptide inhibits angiotensin II-induced NADPH oxidase-dependent ROS via the Src/STAT3 signalling pathway

We had previously demonstrated that the calcitonin gene‐related peptide (CGRP) suppresses the oxidative stress and vascular smooth muscle cell (VSMC) proliferation induced by vascular injury. A recent study also indicated that CGRP protects against the onset and development of angiotensin II (Ang II)‐induced hypertension, vascular hypertrophy and oxidative stress. However, the mechanism behind the effects of CGRP on Ang II‐induced oxidative stress is unclear. CGRP significantly suppressed the level of reactive oxygen species (ROS) generated by NADPH oxidase in Ang II‐induced VSMCs. The Ang II‐stimulated activation of both Src and the downstream transcription factor, STAT3, was abrogated by CGRP. However, the antioxidative effect of CGRP was lost following the expression of constitutively activated Src or STAT3. Pre‐treatment with H‐89 or CGRP_8–37 also blocked the CGRP inhibitory effects against Ang II‐induced oxidative stress. Additionally, both in vitro and in vivo analyses show that CGRP treatment inhibited Ang II‐induced VSMC proliferation and hypertrophy, accompanied by a reduction in ROS generation. Collectively, these results demonstrate that CGRP exhibits its antioxidative effect by blocking the Src/STAT3 signalling pathway that is associated with Ang II‐induced VSMC hypertrophy and hyperplasia.

Identification of Small-Molecule Positive Modulators of Calcitonin-like Receptor-Based Receptors

Class B G protein-coupled receptors are highly therapeutically relevant but challenges remain in identifying suitable small-molecule drugs. The calcitonin-like receptor (CLR) in particular is linked to conditions such as migraine, cardiovascular disease, and inflammatory bowel disease. The CLR cannot act as a cell-surface receptor alone but rather must couple to one of three receptor activity-modifying proteins (RAMPs), forming heterodimeric receptors for the peptides adrenomedullin and calcitonin gene-related peptide. These peptides have extended binding sites across their receptors. This is one reason why there are few small-molecule ligands that can modulate these receptors. Here we describe small molecules that are able to positively modulate the signaling of the CLR with all three RAMPs but are not active at the related calcitonin receptor. These compounds were selected from a β-arrestin recruitment screen, coupled with rounds of medicinal chemistry to improve their activity. Translational potential is shown as the compounds can positively modulate cAMP signaling in a vascular cell line model. Binding experiments do not support an extracellular domain binding site; however, molecular modeling reveals potential allosteric binding sites in multiple receptor regions. These are the first small-molecule positive modulators described for the CLR:RAMP complexes.

Correction of QRS voltage for body mass index does not improve the prediction of fatal and nonfatal cardiovascular events. The Moli-sani study

BACKGROUND AND AIMS

The diagnosis of LVH by ECG may particularly difficult in obese individuals. The aim of this study was to prospectively investigate whether the correction for body mass index (BMI) might improve the prognostic significance for cerebro and cardiovascular events of two electrocardiographic (ECG) criteria for left ventricular hypertrophy (LVH) in a large cohort of Italian adults.

METHODS AND RESULTS

In 18,330 adults (54 ± 11 years, 55% women) from the Moli-sani cohort, obesity was defined using the ATPIII criteria. The Sokolow-Lyon (SL) and Cornell Voltage (CV) criteria were used for ECG-LVH. In overweight and obese subjects, as compared with normal weight, the prevalence of ECG-LVH by the SL index was lower. During follow-up (median 4.3 yrs), 503 cerebro and cardiovascular events occurred. One standard deviation (1-SD) increment in uncorrected and in BMI-corrected SL index and CV was associated with an increased risk of events (HR 1.12, 95% CI 1.02-1.22 and HR 1.16, 95% CI 1.06-1.26 and HR 1.12, 95% CI 1.03-1.23 and HR 1.17, 95% CI 1.07-1.27, respectively for SL and CV). In obese subjects, 1-SD increment in uncorrected CV and in BMI-corrected CV was not associated to a significant risk of events (HR 1.05, 95% CI 0.910-1.22 and HR 1.08, 95% CI 0.95-1.23 respectively). Uncorrected SL index showed a significant association with events, which was marginally stronger with BMI-corrected SL voltage (HR 1.18, 95% CI 1.02-1.37 and HR 1.17, 95% CI 1.04-1.33 respectively, Akaike information criterion change from 3220 to 3218).

CONCLUSIONS

BMI correction of ECG LVH voltage criteria does not significantly improve the prediction of cerebro and cardiovascular events in obese patients in a large cohort at low cardiovascular risk.

Human Placental Vascular Reactivity in Health and Disease: Implications for the Treatment of Pre-eclampsia

Adequate development of the placenta is essential for optimal pregnancy outcome. Pre-eclampsia (PE) is increasingly recognized to be a consequence of placental dysfunction and can cause serious maternal and fetal complications during pregnancy. Furthermore, PE increases the risk of neonatal problems and has been shown to be a risk factor for cardiovascular disease of the mother later in life. Currently, there is no adequate treatment for PE, mainly because its multifactorial pathophysiology remains incompletely understood. It originates in early pregnancy with abnormal placentation and involves a cascade of dysregulated systems in the placental vasculature. To investigate therapeutic strategies it is essential to understand the regulation of vascular reactivity and remodeling of blood vessels in the placenta. Techniques using human tissue such as the ex vivo placental perfusion model provide insight in the vasoactive profile of the placenta, and are essential to study the effects of drugs on the fetal vasculature. This approach highlights the different pathways that are involved in the vascular regulation of the human placenta, changes that occur during PE and the importance of focusing on restoring these dysfunctional systems when studying treatment strategies for PE.

The protective role of calcitonin gene-related peptide (CGRP) in high-glucose-induced oxidative injury in rat aorta endothelial cells

Endothelial dysfunction is considered to be an initial indicator in diabetes-induced macrovascular complications. Evidence has shown that CGRP is an important neuropeptide active in vascular system, especially in vasorelaxation. This study aimed to investigate the role of CGRP in high-glucose-induced endothelial dysfunction in rat aorta endothelial cells (RAECs). Quantitative-real time PCR and western blots were used to determine the efficiency of overexpression and interference of CGRP. After incubation with normal glucose (5.5 mM) or high glucose (33 mM), the cell viability and cell apoptosis were tested. Afterwards, the Nitric Oxide (NO) production, the mRNA expression of inducible nitric oxide synthase (iNOS), endothelial nitric oxide synthase (eNOS) and angiotensin II (Ang II) and the level of reactive oxygen species (ROS) were determined. The involvement of ERK1/2-NOX4 was determined through western blots and the translocation of p47phox was also observed via cell immunofluorescence. CGRP alleviated the high-glucose-induced cell apoptosis while CGRP did not have an obvious impact on cell viability. Meanwhile, CGRP increased the NO production as well as the eNOS mRNA expression and reversely decreased the stimulated expression of iNOS and Ang II by high glucose. In addition, CGRP attenuated the high-glucose-stimulated intracellular ROS production by ERK1/2-NOX4 and the translocation of p47phox. These results indicated the protective role of CGRP in high-glucose-induced oxidative injury in RAECs possibly through inhibiting ERK1/2-NOX4. Our findings might help to further understand the potential role and possible mechanism of CGRP in endothelial dysfunction caused by high glucose.

Blood Pressure Normalization-Independent Cardioprotective Effects of Endogenous, Physical Activity-Induced αCGRP (α Calcitonin Gene-Related Peptide) in Chronically Hypertensive Mice

RATIONALE

αCGRP (α calcitonin gene-related peptide), one of the strongest vasodilators, is cardioprotective in hypertension by reducing the elevated blood pressure.

OBJECTIVE

However, we hypothesize that endogenous, physical activity-induced αCGRP has blood pressure-independent cardioprotective effects in chronic hypertension.

METHODS AND RESULTS

Chronically hypertensive (one-kidney-one-clip surgery) wild-type and αCGRP^-/- sedentary or voluntary wheel running mice were treated with vehicle, αCGRP, or the αCGRP receptor antagonist CGRP8-37. Cardiac function and myocardial phenotype were evaluated echocardiographically and by molecular, cellular, and histological analysis, respectively. Blood pressure was similar among all hypertensive experimental groups. Endogenous αCGRP limited pathological remodeling and heart failure in sedentary, chronically hypertensive wild-type mice. In these mice, voluntary wheel running significantly improved myocardial phenotype and function, which was abolished by CGRP8-37 treatment. In αCGRP^-/- mice, αCGRP treatment, in contrast to voluntary wheel running, improved myocardial phenotype and function. Specific inhibition of proliferation and myofibroblast differentiation of primary, murine cardiac fibroblasts by αCGRP suggests involvement of these cells in αCGRP-dependent blunting of pathological cardiac remodeling.

CONCLUSIONS

Endogenous, physical activity-induced αCGRP has blood pressure-independent cardioprotective effects and is crucial for maintaining cardiac function in chronic hypertension. Consequently, inhibiting endogenous αCGRP signaling, as currently approved for migraine prophylaxis, could endanger patients with hypertension.