Aberrant Expression of Cardiac Troponin-T in Lung Cancer Tissues in Association With Pathological Severity.

Background: Cardiac troponin-T (TNNT2) is exclusively present in cardiac muscle. Measurement of TNNT2 is used for diagnosing acute coronary syndrome. However, its expression may not be limited in myocardium. This study aimed at evaluating the expression of TNNT2 in neoplastic tissues. Methods and Results: We used paraffin-embedded blocks of 68 patients with lung cancer (age, 68 ± 11 years old; early-stage, 33; advance-stage, 35) at Miyazaki University Hospital, Japan between January 1, 2017, and March 31, 2019. We stained the slide sections with primary monoclonal antibody against TNNT2 protein, and assessed the frequency of positive staining, and its association with pathological severity. In addition, we examined whether TNNT2 gene is detected in lung cancer tissues of four patients using reverse transcription-polymerase chain reaction. Immunoreactivity for TNNT2 protein was present in the cytoplasm and nucleus of lung cancer cells. The frequency was 37% (25 of 68) in all patients and was irrespective of histologic type (six of 13, squamous cell carcinoma; 18 of 50, adenocarcinoma; 0 of 4, neuroendocrine cell carcinoma; 1 of 1, large cell carcinoma). The prevalence increased with pathological staging [9% (3 of 33) at early-stage (Stage 0-I); 63% (22 of 35) at advance-stage (Stage II-IV and recurrence)]. In addition, frequency of positive staining for TNNT2 increased with pleural (χ2 = 5.877, P = 0.015) and vascular (χ2 = 2.449, P = 0.118) invasions but decreased with lymphatic invasion (χ2 = 3.288, P = 0.070) in specimens performed surgical resection. Furthermore, TNNT2 mRNA was detected in the resected squamous cell carcinoma and adenocarcinoma tissues. Conclusions: Our data suggest the aberrant expression of TNNT2 in lung cancer and its prevalence increases with pathological severity.

Angiotensin II Induces Aortic Rupture and Dissection in Osteoprotegerin-Deficient Mice.

Background The biological mechanism of action for osteoprotegerin, a soluble decoy receptor for the receptor activator of nuclear factor-kappa B ligand in the vascular structure, has not been elucidated. The study aim was to determine if osteoprotegerin affects aortic structural integrity in angiotensin II (Ang II)-induced hypertension. Methods and Results Mortality was higher (P<0.0001 by log-rank test) in 8-week-old male homozygotes of osteoprotegerin gene-knockout mice given subcutaneous administration of Ang II for 28 days, with an incidence of 21% fatal aortic rupture and 23% aortic dissection, than in age-matched wild-type mice. Ang II-infused aorta of wild-type mice showed that osteoprotegerin immunoreactivity was present with proteoglycan. The absence of osteoprotegerin was associated with decreased medial and adventitial thickness and increased numbers of elastin breaks as well as with increased periostin expression and soluble receptor activator of nuclear factor-kappa B ligand concentrations. PEGylated human recombinant osteoprotegerin administration decreased all-cause mortality (P<0.001 by log-rank test), the incidence of fatal aortic rupture (P=0.08), and aortic dissection (P<0.001) with decreasing numbers of elastin breaks, periostin expressions, and soluble receptor activator of nuclear factor-kappa B ligand concentrations in Ang II-infused osteoprotegerin gene-knockout mice. Conclusions These data suggest that osteoprotegerin protects against aortic rupture and dissection in Ang II-induced hypertension by inhibiting receptor activator of nuclear factor-kappa B ligand activity and periostin expression.

Aberrant accumulation of TMEM43 accompanied by perturbed transmural gene expression in arrhythmogenic cardiomyopathy.

Arrhythmogenic cardiomyopathy (ACM) caused by TMEM43 p.S358L is a fully penetrant heart disease that results in impaired cardiac function or fatal arrhythmia. However, the molecular mechanism of ACM caused by the TMEM43 variant has not yet been fully elucidated. In this study, we generated knock-in (KI) rats harboring a Tmem43 p.S358L mutation and established induced pluripotent stem cells (iPSCs) from patients based on the identification of TMEM43 p.S358L variant from a family with ACM. The Tmem43-S358L KI rats exhibited ventricular arrhythmia and fibrotic myocardial replacement in the subepicardium, which recapitulated the human ACM phenotype. The four-transmembrane protein TMEM43 with the p.S358L variant (TMEM43S358L ) was found to be modified by N-linked glycosylation in both KI rat cardiomyocytes and patient-specific iPSC-derived cardiomyocytes. TMEM43S358L glycosylation increased under the conditions of enhanced endoplasmic reticulum (ER) stress caused by pharmacological stimulation or age-dependent decline of the ER function. Intriguingly, the specific glycosylation of TMEM43S358L resulted from the altered membrane topology of TMEM43. Moreover, unlike TMEM43WT , which is mainly localized to the ER, TMEM43S358L accumulated at the nuclear envelope of cardiomyocytes with the increase in glycosylation. Finally, our comprehensive transcriptomic analysis demonstrated that the regional differences in gene expression patterns between the inner and outer layers observed in the wild type myocardium were partially diminished in the KI myocardium prior to exhibiting histological changes indicative of ACM. Altogether, these findings suggest that the aberrant accumulation of TMEM43S358L underlies the pathogenesis of ACM caused by TMEM43 p.S358L variant by affecting the transmural gene expression within the myocardium.

The Cytokine Expression in Patients with Cardiac Complication after Immune Checkpoint Inhibitor Therapy.

We herein report the cytokine expression at different stages for three patients who developed cardiac complications after immune checkpoint inhibitor (ICI) therapy. Case 1 with biopsy-proven myocarditis showed increased levels of interleukin (IL)-8, monocyte chemotactic and activating factor, and granulocyte macrophage colony-stimulating factor (GM-CSF) when he developed Takotsubo cardiomyopathy. Case 2 with subclinical myocarditis showed predominant activation of IL-8 during the progressive clinical course. Case 3 with cytokine-releasing syndrome showed substantial activations of IL-6, IL-8, GM-CSF, and interferon-γ. Our data suggest the development of unique cytokine activation in individual patients with cardiac complications after ICI therapy.

Non-canonical Expression of Cardiac Troponin-T in Neuroendocrine Ethmoid Sinus Carcinoma Following Immune Checkpoint Blockade.

We describe the case of a patient with neuroendocrine ethmoid sinus carcinoma, who exhibited markedly elevated levels of serum cardiac troponin-T and creatine kinase (CK)-MB isoenzyme without any symptom after the administration of nivolumab, immune checkpoint inhibitor. The repeated 12-leads-electrocardiogram did not show any changes in the ST-T segments or arrhythmias. The echocardiogram showed normal ranges of left ventricular contraction in the clinical course. Cardiac magnetic resonance imaging showed minimal myocardial edema and inflammation. Blood clots in the metastatic lesion of bone marrow aspirates exhibited positive staining for cardiac troponin-T and CK-MB in the cytoplasm and nucleoplasm of neoplastic cells. Although we did not perform a second cardiac magnetic resonance imaging and autopsy, we postulate that the attack of the neoplastic cells by the immune checkpoint inhibitor or the secretion from neoplastic cell-derived extracellular vesicles may have exacerbated the increase in concentrations of these molecules in the blood. Our case should warrant consideration a false-positive value of cardiac troponin-T and CK-MB can be obtained in cases with malignancy.

Blockade of the angiotensin II type 1 receptor increases bone mineral density and left ventricular contractility in a mouse model of juvenile Paget disease.

Juvenile Paget disease (JPD1), an autosomal-recessive disorder, is characterized by extremely rapid bone turnover due to osteoprotegerin deficiency. Its extra-skeletal manifestations, such as hypertension and heart failure, suggest a pathogenesis with shared skeletal and cardiovascular system components. In spite of this, the effects of anti-hypertensive drugs on bone morphometry remain unknown. We administered an angiotensin II type 1 receptor blocker, olmesartan (5 mg/kg/day) to 8-week-old male mice lacking the osteoprotegerin gene, with and without 1 µg/kg/min of angiotensin II infusion for 14 days. Olmesartan treatment decreased systolic blood pressure, and echocardiography showed increased left ventricular systolic contractility. Three-dimensional micro-computed tomography scans demonstrated that olmesartan treatment increased trabecular bone volume (sham, +176%; angiotensin II infusion, +335%), mineral density (sham, +150%; angiotensin II infusion, +313%), and trabecular number (sham, +407%; angiotensin II infusion, +622%) in the tibia. Olmesartan increased cortical mineral density (sham, +19%; angiotensin II infusion, +24%), decreased the cortical bone section area (sham, -16%; angiotensin II infusion, -18%), decreased thickness (sham, -18%; angiotensin II infusion, -31%), and decreased the lacunar area (sham, -41%; angiotensin II infusion, -27%) in the tibia. Similar trend was observed in the femur. Moreover, olmesartan decreased angiotensin II-induced increases in tartrate-resistant acid phosphatase concentrations in plasma, but it affected neither type I procollagen N-terminal propeptides, nor the receptor activator of nuclear factor kappa-B ligand. Our data suggest that blockade of the angiotensin II type 1 receptor improves bone vulnerability, and helps to maintain the heart's structural integrity in osteoprotegerin-deficient mice.

Adrenomedullin: Continuing to explore cardioprotection.

Adrenomedullin (AM), a peptide isolated from an extract of human pheochromocytoma, comprises 52 amino acids with an intramolecular disulfide bond and amidation at the carboxy-terminus. AM is present in various tissues and organs in rodents and humans, including the heart. The peptide concentration increases with cardiac hypertrophy, acute myocardial infarction, and overt heart failure in the plasma and the myocardium. The principal function of AM in the cardiovascular system is the regulation of the vascular tone by vasodilation and natriuresis via cyclic adenosine monophosphate-dependent or -independent mechanism. In addition, AM may possess unique properties that inhibit aldosterone secretion, oxidative stress, apoptosis, and stimulation of angiogenesis, resulting in the protection of the structure and function of the heart. The AM receptor comprises a complex between calcitonin receptor-like receptor (CLR) and receptor activity-modifying protein (RAMP) 2 or 3, and the AM-CLR/RAMP2 system is essential for heart development during embryogenesis. Small-scale clinical trials have proven the efficacy and safety of recombinant AM peptide therapy for heart failure. Gene delivery and a modified AM peptide that prolongs the half-life of the native peptide could be an innovative method to improve the efficacy and benefit of AM in clinical settings. In this review, we focus on the pathophysiological roles of AM and its receptor system in the heart and describe the advances in AM and proAM-derived peptides as diagnostic biomarkers as well as the therapeutic application of AM and modified AM for cardioprotection.

Angiotensin II Stimulation of Cardiac Hypertrophy and Functional Decompensation in Osteoprotegerin-Deficient Mice.

Circulating and myocardial expressions of receptor activator of nuclear factor-κb ligand and osteoprotegerin are activated in heart failure; however, it remains to be determined their pathophysiological roles on left ventricular structure and function in interaction with renin-angiotensin system. We conducted experiments using 8-week-old osteoprotegerin(-/-) mice and receptor activator of nuclear factor-κb ligand-transgenic mice to assess whether they affect the angiotensin II-induced left ventricular remodeling. Subcutaneous infusion of angiotensin II to osteoprotegerin(-/-) mice progressed the eccentric hypertrophy, resulting in left ventricular systolic dysfunction for 28 days, and this was comparable with wild-type mice, showing concentric hypertrophy, irrespective of equivalent elevation of systolic blood pressure. The structural alteration was associated with reduced interstitial fibrosis, decreased procollagen α1 and syndecan-1 expressions, and the increased number of apoptotic cells in the left ventricle, compared with wild-type mice. In contrast, angiotensin II infusion to the receptor activator of nuclear factor-κb ligand-transgenic mice revealed the concentric hypertrophy with preserved systolic contractile function. Intraperitoneal administration of human recombinant osteoprotegerin, but not subcutaneous injection of anti-receptor activator of nuclear factor-κb ligand antibody, to the angiotensin II-infused osteoprotegerin(-/-) mice for 28 days ameliorated the progression of heart failure without affecting systolic blood pressure. These results underscore the biological activity of osteoprotegerin in preserving myocardial structure and function during the angiotensin II-induced cardiac hypertrophy, independent of receptor activator of nuclear factor-κb ligand activity. In addition, the antiapoptotic and profibrotic actions of osteoprotegerin that emerged from our data might be involved in the mechanisms.

Cardiac hypertrophy is exacerbated in aged mice lacking the osteoprotegerin gene.

AIMS: Osteoprotegerin (OPG) may play a role in the progression of cardiac hypertrophy and heart failure. However, its pathophysiological role in changes in cardiac structure and function with ageing remains to be elucidated. METHODS AND RESULTS: We conducted experiments using 2.5- and 12-month-old OPG(-/-) mice and age-matched wild-type (WT) mice and compared the morphology and function of the left ventricle (LV). Both 2.5- and 12-month-old OPG(-/-) mice showed a higher systolic blood pressure and a greater heart weight/body weight ratio than age-matched WT mice. Twelve-month-old OPG(-/-) mice had a significantly larger LV chamber and reduced wall thickness compared with age-matched WT mice, and contractile function was decreased. The morphological differences were accompanied by an increase in the number of apoptotic cells and activation of tumour necrosis factor-related apoptosis-inducing ligand (TRAIL) in the LV of 12-month-old OPG(-/-) mice. Correspondingly, OPG small interfering RNA induced the expressions of TRAIL and cleaved caspase-3 in cultured cardiac myocytes. In addition, these mice revealed a decrease in interstitial fibrosis, activation of matrix metalloproteinase (MMP)-2 and tissue inhibitors of MMP-1 and -2, and inactivation of procollagen α1 synthesis. Moreover, intraperitoneal administration of recombinant OPG to either 2.5- or 12-month-old OPG(-/-) mice for 28 days led to partial improvement of LV structure and function without affecting systolic blood pressure. CONCLUSION: These results suggest that OPG plays a role in preserving myocardial structure and function with ageing through a reduction in apoptosis and preservation of the matrix structure. In addition, this appears to be independent of effects on the vasculature.

Impact of age-dependent adventitia inflammation on structural alteration of abdominal aorta in hyperlipidemic mice.

BACKGROUND: The adventitia is suggested to contribute to vascular remodeling; however, the site-selective inflammatory responses in association with the development of atherosclerosis remain to be elucidated. METHODS AND RESULTS: Wild-type or apolipoprotein E knockout male C57BL/6J background mice were fed standard chow for 16, 32, and 52 weeks, and the morphology of the aortic arch, descending aorta, and abdominal aorta was compared. Atheromatous plaque formation progressed with age, particularly in the aortic arch and abdominal aorta but not in the descending aorta. In addition, we found that the numbers of macrophages, T-lymphocytes, and microvessels, assessed by anti-F4/80, CD3, and CD31 antibodies, were higher in the adventitia of the abdominal aorta at 52 weeks. These numbers were positively correlated with plaque formation, but negatively correlated with elastin content, resulting in the enlargement of the total vessel area. In aortic tissues, interleukin-6 levels increased in the atheromatous plaque with age, whereas the level of regulated on activation, normal T cell expressed and secreted (RANTES) increased with age, and compared with other sites, it was particularly distributed in inflammatory cells in the adventitia of the abdominal aorta. CONCLUSION: This study suggests that adventitial inflammation contributes to the age-dependent structural alterations, and that the activation/inactivation of cytokines/chemokines is involved in the process.

Inhibition of development of abdominal aortic aneurysm by glycolysis restriction.

OBJECTIVE: The mechanisms underlying abdominal aortic aneurysm development remain unknown. We hypothesized that acceleration of glucose metabolism with the upregulation of glucose transporters is associated with abdominal aortic aneurysm development. METHODS AND RESULTS: Enhanced accumulation of the modified glucose analogue 18 fluoro-deoxyglucose by positron emission tomography imaging in the human abdominal aortic aneurysm was associated with protein expressions of glucose transporters-1 and -3, assessed by Western blot. The magnitude of glucose transporter-3 expression was correlated with zymographic matrix metalloproteinase-9 activity. Intraperitoneal administration of glycolysis inhibitor with 2-deoxyglucose significantly attenuated the dilatation of abdominal aorta induced by periaortic application of CaCl(2) in C57BL/6J male mice or reduced the aneurysmal formation in angiotensin II-infused apolipoprotein E knockout male mice. In monocytic cell line induced by phorbol 12-myristate 13-acetate or ex vivo culture obtained from human aneurysmal tissues, 2-deoxyglucose abrogated the matrix metalloproteinase-9 activity and interleukin-6 expression in these cells/tissues. Moreover, 2-deoxyglucose attenuated the survival/proliferation of monocytes and the adherence of them to vascular endothelial cells. CONCLUSIONS: This study suggests that the enhanced glycolytic activity in aortic wall contributes to the pathogenesis of aneurysm development. In addition, pharmacological intervention in glycolytic activity might be a potential therapeutic target for the disorder.

Adrenomedullin production is increased in colorectal adenocarcinomas; its relation to matrix metalloproteinase-9.

Adrenomedullin (AM) is highly expressed in various cancer cell lines, suggesting a possible association with cancer growth. In the present study, we examined the expression and/or concentration of AM, its related peptide, adrenomedullin2/intermedin (AM2/IMD) and their receptors in human colorectal cancer and the surrounding normal tissue. In addition, we assessed the correlation between the expression of AM and AM2/IMD with that of vascular endothelial growth factor (VEGF)-A and matrix metalloproteinase (MMP)-9. Using a specific immunoradiometric assay, we found that AM concentrations were 2-11-fold higher in colorectal cancer tissues than in the surrounding normal tissues. Moreover, real-time quantitative RT-PCR showed that the expression levels of preproAM (+548%), preproAM2/IMD (+2674%), calcitonin receptor-like receptor (CLR) (+518%), receptor activity modifying protein (RAMP)2 (+281%), RAMP3 (+178%), VEGF-A (+277%) and MMP-9 (+864%) mRNAs were significantly higher in cancer tissues than in the surrounding normal tissues, and there was a positive correlation between the gene expressions of MMP-9 and preproAM (r=0.352; p=0.005), but not with preproAM2/IMD (r=0.041, p=0.406). Both AM and AM2/IMD immunoreactivity were detected mainly within cancer cells, whereas MMP-9 immunoreactivity was mostly seen in the surrounding stroma. These findings suggest that AM produced in colorectal tumors acts in concert with MMP-9 in the stroma to contribute to the pathogenesis of colorectal cancer.

[Macrophage: pathogenesis in the progression of atherosclerosis].

Atherosclerotic changes in aorta or coronary arteries involve the accumulation and activation of macrophages, which this type of cell is present not only in plaques of intima but in the outer-media and adventitia. Macrophages play important roles in the progression of atherosclerosis by exhibiting unique characteristics under the various stimuli, evolving the plaque instability, thrombus formation and remodeling. Recent studies have shown the molecules-associated with metabolism, such as sirtuin-1 and peroxisome proliferator -activated receptor gamma in macrophages, appear to be involved to modulate the atherosclerotic process. In addition, macrophages work coordinately with other immune cells like mast cells. Thus, modulation of activation and function in macrophages might be a potential therapeutic target in attenuating the atherosclerosis-based cardiovascular diseases.

Pharmacological stimulation of soluble guanylate cyclase modulates hypoxia-inducible factor-1alpha in rat heart.

Mechanical load and ischemia induce a series of adaptive physiological responses by activating the expression of O(2)-regulated genes, such as hypoxia inducible factor-1alpha (HIF-1alpha). The aim of this study was to explore the interaction between HIF-1alpha and soluble guanylate cyclase (sGC) and its second messenger cGMP in cultured cardiomyocytes exposed to hypoxia and in pressure-overloaded heart. In cultured cardiomyocytes of neonatal rats, either sGC stimulator BAY 41-2272 or cGMP analog 8-bromo-cGMP decreased the hypoxia (1% O(2)/5% CO(2))-induced HIF-1alpha expression, whereas the inhibition of protein kinase G by KT-5823 reversed the effect of BAY 41-2272 on the expression under hypoxic conditions. In pressure-overloaded heart induced by suprarenal aortic constriction (AC) in 7-wk-old male Wistar rats, the administration of BAY 41-2272 (2 mg.kg(-1).day(-1)) for 14 days significantly suppressed the protein expression of HIF-1alpha (P < 0.05), vascular endothelial growth factor (P < 0.01), and the number of capillary vessels (P < 0.01) induced by pressure overload. This study suggests that the pharmacological sGC-cGMP stimulation modulates the HIF-1alpha expression in response to hypoxia or mechanical load in the heart.

Adrenomedullin in mast cells of abdominal aortic aneurysm.

OBJECTIVES: Produced by vascular walls, adrenomedullin (AM) exerts antifibrotic actions in the process of cardiovascular remodeling. The purpose of this study was to examine the pathophysiological role of AM in the development of human abdominal aortic aneurysm (AAA). METHODS AND RESULTS: Immunohistochemical analyses revealed that vascular smooth muscle cells in the media were positive for AM in the early stage of atherosclerotic aorta. Intense immunoreactivity was observed in mast cells of the outer media and adventitia of AAA, and the number of mast cells was greater (p < 0.01) in AAA than in atherosclerotic aorta without any aneurysmal change. To determine the role of AM in mast cells, we examined cultured human mast cell leukemia line-1 (HMC-1) and fibroblasts isolated from AAA patients. Cultured HMC-1 cells were found to express preproAM gene and release AM peptide into the cultured media. When assessed by collagenase-sensitive [3H]proline incorporation and procollagen type I C-peptide secretion, collagen synthesis in co-culture of HMC-1 and the fibroblasts was reduced by 10(-6) mol/L synthetic AM, while conversely, it increased following blockade of the action of endogenous AM with 10 microg/mL anti-AM monoclonal antibody. CONCLUSION: The present study suggests an anti-fibrotic role for AM released from mast cells, providing new insight into the biological actions of mast cell-derived AM in the development of AAA.

Adrenomedullin: a protective factor for blood vessels.

Adrenomedullin (AM) is a vasodilator peptide having a wide range of biological actions such as reduction of oxidative stress and inhibition of endothelial cell apoptosis. The AM gene is expressed in vascular walls, and AM was found to be secreted from cultured vascular endothelial cells, smooth muscle cells, and adventitial fibroblasts. Plasma AM levels in patients with arteriosclerotic vascular diseases are elevated in possible association with the severity of the disease. When administered over a relatively short period, AM dilates blood vessels via an endothelium-dependent or independent mechanism. Experiments in vitro have shown that AM exerts multiple actions on cultured vascular cells, which are mostly protective or inhibitory against vascular damage and progression of arteriosclerosis. Either prolonged infusion or overexpression of AM suppressed intimal thickening, fatty streak formation, and perivascular hyperplasia in rodent models for vascular remodeling or atherosclerosis. Intimal thickening induced by periarterial cuff was more severe in AM gene-knockout mice than their littermates, suggesting a protective role for endogenous AM. Moreover, AM has recently been suggested to possess angiogenetic properties. Collectively, a body of evidence suggests that AM participates in the mechanism against progression of vascular damage and remodeling, thereby alleviating the ischemia of tissues and organs.

Beyond vasodilation: the antioxidant effect of adrenomedullin in Dahl salt-sensitive rat aorta.

We have investigated the antioxidant effect of adrenomedullin (AM) on endothelial function in the Dahl salt-sensitive (DS) rat hypertension model. Dahl salt-resistant (DR) and DS rats were fed an 8% NaCl diet. In addition, the DS rats were subcutaneously infused with either saline or recombinant human AM for 4 weeks. Although systolic blood pressures measured weekly in AM- and saline-infused rats did not significantly differ, aortic O2*- levels were significantly (P<0.01) higher in the latter. Likewise, both endothelial nitric oxide synthase (eNOS) mRNA and protein were significantly higher in saline-infused DS rats. Infusion of AM reduced both O2*- and eNOS expression to levels comparable to those seen in DR rats. AM infusion also upregulated the gene expression of guanosine-5'-triphosphate cyclohydrolase I and downregulated the expression of p22(phox), suggesting that AM increased the NOS coupling and bioavailability of NO. AM possesses significant antioxidant properties that improve endothelial function.

Adrenomedullin alleviates not only neointimal formation but also perivascular hyperplasia following arterial injury in rats.

Producing components of the extracellular matrix, the vascular adventitia has been recognized as an important modulator of the vascular remodeling process, which determines the vessel architecture. In this study, we examined the effect of the vasodilator peptide adrenomedullin on vascular remodeling induced by balloon injury of rat carotid arteries. Endothelial denudation with wall stretch by ballooning not only induced neointimal formation accompanied with a reduced ratio of the lumen to vessel area, but also increased the fibroblast number and collagen deposition in the adventitial layer. When compared with the saline infusion, intravenous adrenomedullin infusion at 200 ng/h for 14 days suppressed the neointimal formation (-33%, P=0.033), reversing the ratio of lumen to vessel ratio (P=0.030), without affecting systolic blood pressure. Moreover, the adrenomedullin infusion decreased the number of adventitial fibroblasts (-41%, P<0.001) and the collagen deposition (-36%, P=0.006) in the adventitial layer of the injured artery. In conclusion, the intravenous adrenomedullin infusion effectively attenuates vascular remodeling following the arterial injury via suppression of hyperplasia in the intima and adventitia, suggesting a potential of adrenomedullin as a therapeutic tool against vascular remodeling.

Antifibrotic effect of adrenomedullin on coronary adventitia in angiotensin II-induced hypertensive rats.

OBJECTIVE: The extracellular matrix (ECM) determines the structural integrity of the heart and vasculature, participating in cardiovascular remodeling. We previously reported that adrenomedullin (AM) inhibited cellular proliferation and protein synthesis of cardiac fibroblasts; however, the precise mechanisms of AM actions as an antifibrotic factor remain unknown. The purpose of this study was to examine the biological actions of AM against the profibrotic factor angiotensin II (Ang II) in coronary adventitia. METHODS AND RESULTS: Rats with hypertension induced by Ang II infusion were administered 0.06 mug/kg/min recombinant human AM subcutaneously for 14 days. The AM infusion significantly (p<0.05) reduced the Ang II-induced increase of coronary adventitial fibroblasts expressing Ki-67 and alpha-smooth muscle actin (alpha-SMA) in the left ventricle, by 65%, and 62%, respectively, without affecting systolic blood pressure, left ventricle/body weight, or cross-sectional area of myocardial fibers. Collagen deposition of coronary arteries was reduced by the AM infusion (-24%, p<0.01), and these effects of AM were accompanied by significant reductions in gene expression of type 1 collagen (-49%, p<0.05) and transforming growth factor-beta1 (TGF-beta1) (-55%, p<0.01). In cultured cardiac fibroblasts, 10(-7) mol/L AM exerted an inhibitory effect on TGF-beta1-induced alpha-SMA expression (p<0.01) that was mimicked by 8-bromo-cAMP and attenuated by the protein kinase A inhibitor H-89. CONCLUSION: AM decreased Ang II-induced collagen deposition surrounding the coronary arteries, inhibiting myofibroblast differentiation and expressions of ECM-related genes in rats. The present findings further support the biological action of AM as an antifibrotic factor in vascular remodeling.