adrenomedullin and Hyperplasia

Atypical chemokine receptor 3 (ACKR3) is a scavenger of the chemokines CXCL11 and CXCL12 and of several opioid peptides. Additional evidence indicates that ACKR3 binds two other non-chemokine ligands, namely the peptide hormone adrenomedullin (AM) and derivatives of the proadrenomedullin N-terminal 20 peptide (PAMP). AM exhibits multiple functions in the cardiovascular system and is essential for embryonic lymphangiogenesis in mice. Interestingly, AM-overexpressing and ACKR3-deficient mouse embryos both display lymphatic hyperplasia. Moreover, in vitro evidence suggested that lymphatic endothelial cells (LECs), which express ACKR3, scavenge AM and thereby reduce AM-induced lymphangiogenic responses. Together, these observations have led to the conclusion that ACKR3-mediated AM scavenging by LECs serves to prevent overshooting AM-induced lymphangiogenesis and lymphatic hyperplasia. Here, we further investigated AM scavenging by ACKR3 in HEK293 cells and in human primary dermal LECs obtained from three different sources in vitro. LECs efficiently bound and scavenged fluorescent CXCL12 or a CXCL11/12 chimeric chemokine in an ACKR3-dependent manner. Conversely, addition of AM induced LEC proliferation but AM internalization was found to be independent of ACKR3. Similarly, ectopic expression of ACKR3 in HEK293 cells did not result in AM internalization, but the latter was avidly induced upon co-transfecting HEK293 cells with the canonical AM receptors, consisting of calcitonin receptor-like receptor (CALCRL) and receptor activity-modifying protein (RAMP)2 or RAMP3. Together, these findings indicate that ACKR3-dependent scavenging of AM by human LECs does not occur at ligand concentrations sufficient to trigger AM-induced responses mediated by canonical AM receptors.

Topics: Adrenomedullin; Chemokine CXCL11; Endothelial Cells; HEK293 Cells; Humans; Hyperplasia; Receptors, Adrenomedullin; Receptors, CXCR

Growth promoting signals from the epicardium are essential for driving myocardial proliferation during embryogenesis. In adults, these signals become reactivated following injury and promote angiogenesis and myocardial repair. Therefore, identification of such paracrine factors could lead to novel therapeutic strategies. The multi-functional peptide adrenomedullin (Adm 5 gene, AM 5 protein) is required for normal heart development. Moreover, elevated plasma AM following myocardial infarction offers beneficial cardioprotection and serves as a powerful diagnostic and prognostic indication of disease severity.. Here, we developed a new model of Adm overexpression by stabilizing the Adm mRNA through gene-targeted replacement of the endogenous 30 untranslated region. As expected, Admhi/hi mice express three-times more AM than controls in multiple tissues, including the heart. Despite normal blood pressures, Admhi/hi mice unexpectedly showed significantly enlarged hearts due to increased cardiac hyperplasia during development. The targeting vector was designed to allow for reversion to wild-type levels by means of Cre-mediated modification. Using this approach, we demonstrate that AM derived from the epicardium, but not the myocardium or cardiac fibroblast, is responsible for driving cardiomyocyte hyperplasia.. AM is produced by the epicardium and drives myocyte proliferation during development, thus representing a novel and clinically relevant factor potentially related to mechanisms of cardiac repair after injury.

Topics: Adrenomedullin; Animals; Blotting, Western; Bromodeoxyuridine; Cell Cycle; DNA Primers; Genetic Vectors; Heart; Hyperplasia; Mice; Mice, Mutant Strains; Myocardium; Myocytes, Cardiac; Pericardium; Real-Time Polymerase Chain Reaction; RNA Stability; Signal Transduction

Adrenomedullin (ADM) is a multifunctional 52-amino acid peptide involved in numerous physiological and pathological processes, including angiogenesis, growth regulation, differentiation, and vasodilation. ADM is thought to act through the G protein-coupled receptor calcitonin receptor-like receptor, with specificity being conferred by receptor-associated modifying protein 2. The aim of the present study was to clarify the roles of ADM status, and tumor vessels in endometrium. Specimens were examined for ADM, microvessel density (MVD), area of venules (AV) and Bcl-2 oncoprotein using an immunoperoxidase method. The difference of ADM between normal proliferative phase and hyperplasia without atypia was significant (P < 0.05). The level of Bcl-2 was significantly different between hyperplasia without atypia and hyperplasia with atypia (P < 0.05). ADM, MVD and AV in the endometrium increased in a stepwise manner from normal, simple or complex hyperplasia with or without atypia to grade 1 adenocarcinoma. In contrast, expression of Bcl-2 oncoprotein was decreased. These parameters identify the role of ADM expression and Bcl-2 protein in relation to cell growth and vasodilating in the neoplastic changes.

Topics: Adenocarcinoma; Adrenomedullin; Adult; Endometrial Neoplasms; Endometrium; Female; Humans; Hyperplasia; Immunohistochemistry; Microvessels; Middle Aged; Neovascularization, Pathologic; Proto-Oncogene Proteins c-bcl-2

Arterial wall injury leads to inflammatory reaction and release of growth factors that may mediate intimal regrowth. It is hypothesized that the neointimal cells may originate from adventitial myofibroblasts, medial smooth muscle cells, or differentiated bone marrow derived cells. Adrenomedullin (AM), an auto/paracrine cardiovascular peptide that is secreted from fibroblasts, endothelial cells, and vascular smooth muscle cells, may have a regulatory role in the intimal regeneration. In order to investigate the role of AM in neointimal growth, stimulation of stem cell migration, and apoptosis, we overexpressed AM with recombinant adenovirus in a rat arterial injury model. The intimae were significantly thinner in the arteries treated with AM adenovirus compared to the control group. Intima/media ratios were 0.48 +/- 0.18 and 1.01 +/- 0.20 (P < 0.05) in the AM group and the control group, respectively. In addition, a significantly higher apoptotic index of neointimal cells was seen in the AM gene transfer group compared to the control (2.78 +/- 0.5 vs. 0.57 +/- 0.20, P < 0.01). The neointimal cells stained positive for alpha-smooth muscle actin and negative for desmin suggesting possible myofibroblast origin. Very few c-Kit+ or MDR1+ cells were detected 2 weeks after the injury. We conclude that AM overexpression inhibits neointimal growth. The inhibition is associated with enhanced apoptosis of the neointimal cells which may be of myofibroblast origin.

Topics: Actins; Adenoviridae; Adrenomedullin; Animals; Apoptosis; Arteries; Carotid Arteries; Desmin; Gene Expression; Hyperplasia; Male; Peptides; Rats; Rats, Sprague-Dawley; Stem Cells; Transduction, Genetic; Transgenes; Tunica Intima

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.

Topics: Adrenomedullin; Animals; Blood Pressure; Carotid Arteries; Carotid Artery Injuries; Hyperplasia; Male; Peptides; Rats; Rats, Sprague-Dawley; Tunica Intima; Vasodilator Agents

In our previous study, adrenomedullin (AM) overexpression could limit the arterial intimal hyperplasia induced by cuff injury in rats. However, it remains to be elucidated whether endogenous AM plays a role against vascular injury.. We used the AM knockout mice to investigate the effect of endogenous AM. Compared with wild-type (AM+/+) mice, heterozygous AM knockout (AM+/-) mice had the increased intimal thickening of the cuff-injured femoral artery, concomitantly with lesser AM staining. In AM+/- mice, cuff placement increased both the production of superoxide anions (O2-) measured by coelentarazine chemiluminescence and the immunostaining of p67phox and gp91phox, subunits of NAD(P)H oxidase in the adventitia, associated with the increment of CD45-positive leukocytes, suggesting that the stimulated formation of radical oxygen species accompanied chronic adventitial inflammation. Not only the AM gene transfection but also the treatment of NAD(P)H oxidase inhibitor apocynin and membrane-permeable superoxide dismutase mimetic tempol could limit cuff-induced intimal hyperplasia in AM+/- mice, associated with the inhibition of O2- formation in cuff-injured artery.. The overproduction of oxidative stress induced by the increased NAD(P)H oxidase activity might be involved in cuff-injured arterial intimal hyperplasia in AM+/- mice. Thus, it is suggested that endogenous AM possesses a protective action against the vascular response to injury, possibly through the inhibition of oxidative stress production.

Topics: Acetophenones; Adrenomedullin; Animals; Arterial Occlusive Diseases; Cell Movement; Cyclic N-Oxides; Enzyme Inhibitors; Femoral Artery; Hyperplasia; Leukocyte Common Antigens; Leukocytes; Membrane Glycoproteins; Mice; Mice, Knockout; NADPH Oxidase 2; NADPH Oxidases; Oxidative Stress; Peptides; Phosphoproteins; Spin Labels; Superoxides; Tunica Intima

Adrenomedullin (ADM) is a new potent vasorelaxant peptide identified originally in extracts of pheochromocytoma, and is widely distributed within the tissue. Although histopathological studies have demonstrated the presence of ADM-immunoreactivity (ir-ADM) in some human neuroendocrine tumors (such as insulinoma, pituitary adenoma, and gastrointestinal neuroendocrine tumors), data on the presence of ADM in normal and pathological parathyroid gland are not available. Plasma AM concentrations were recently reported to be elevated in patients with PHP (primary hyperparathyroidism). The aim of our study was to determine tissue distribution of ir-AM in 34 patients with PHP (27 female and 7 male, mean age 50 +/- 6 years) undergoing surgery. Six normal parathyroid samples incidentally found during thyroidectomy for neoplastic diseases and ten sections of human rectus abdominis muscle tissue were used as controls (C). Adenomatous parathyroids were found in 22 PHP and hyperplastic parathyroids in twelve PHP patients. Four hyperplastic parathyroids were found in three PHP patients and three parathyroids in 10 PHP patients. Eight parathyroids revealed a prevalent diffuse growth pattern and four showed a prevalent nodular growth pattern. Immunohistochemical ADM expression was seen in seven of twelve (58.3 %) hyperplastic parathyroids and in fourteen of twenty-two (66.6 %) adenomatous glands. Parathyroid chief cells showed strong cytoplasmatic staining, whereas oncocytic cells showed a faintly aspecific cytoplasmatic staining. Normal parathyroids were negative for ir-ADM. In conclusion, we found the presence of ADM in parathyroid chief cells of PHP patients using immunohistochemistry in our study.

Topics: Adenoma; Adrenomedullin; Adult; Female; Humans; Hyperparathyroidism; Hyperplasia; Immunohistochemistry; Male; Middle Aged; Parathyroid Glands; Parathyroid Neoplasms; Peptides; Tissue Distribution

Several in vitro studies have implicated that adrenomedullin (AM) plays an important role in the pathogenesis of vascular injury and fatty streak formation. To test this possibility in vivo, we evaluated 2 experimental models using transgenic mice overexpressing AM in a vessel-selective manner (AMTg mice).. Placement of a periarterial cuff on femoral arteries resulted in neointimal formation at 2 to 4 weeks to a lesser extent in AMTg mice than in their wild-type littermates (at 28 days, intima/media area ratio 0.45+/-0.14 versus 1.31+/-0.41, respectively; P<0.001). This vasculoprotective effect observed in AMTg mice was inhibited by N(omega)-nitro-L-arginine methyl ester. We further examined the effect of AM on hypercholesterolemia-induced fatty streak formation by crossing AMTg mice with apolipoprotein E knockout mice (ApoEKO mice). The extent of the formation of fatty streak lesions was significantly less in ApoEKO/AMTg mice than in ApoEKO mice (percent lesion area 12.0+/-3.9% versus 15.8+/-2.8%, respectively; P<0.05). Moreover, endothelium-dependent vasodilatation as indicative of NO production was superior in AMTg/ApoEKO mice compared with ApoEKO mice.. Taken together, our data demonstrated that AM possesses a vasculoprotective effect in vivo, which is at least partially mediated by NO.

Topics: Adipose Tissue; Adrenomedullin; Animals; Apolipoproteins E; Calcitonin Gene-Related Peptide; Femoral Artery; Hydralazine; Hyperplasia; Mice; Mice, Knockout; Mice, Transgenic; NG-Nitroarginine Methyl Ester; Nitric Oxide; Peptide Fragments; Peptides; Tunica Intima

Pulmonary neuroendocrine (NE) cells are found as clusters called neuroepithelial bodies (NEBs) or as single cells scattered in the respiratory epithelium. They express a variety of bioactive peptides, and they are thought to be the origin of NE lung tumors. Proadrenomedullin N-terminal 20 peptide (PAMP) is a peptide derived from the same precursor as adrenomedullin (AM). AM and PAMP are C-terminally amidated during their processing by a well-characterized amidating enzyme, peptidylglycine alpha-amidating monooxygenase (PAM). We explored AM, PAMP, and PAM expression as markers for NE hyperplasia in three rodent species (Fischer 344 rats, Syrian golden hamsters, and A/J mice) after a single intratracheal instillation of crystalline silica (quartz), which was previously found to induce different reactions in the three species. Rats developed a marked silicosis, with alveolar and bronchiolar hyperplasia and formation of peripheral lung epithelial tumors. Mice developed a moderate degree of silicosis, but not epithelial hyperplasia or tumors. Hamsters showed dust-storage lesions, but not silicosis or tumors. NE cells were immunolabeled for calcitonin gene-related peptide (CGRP), AM, PAMP, and PAM in serial sections of each lung. The numbers of positive NEBs per lung area and positive cells per NEB were quantified. A marked hyperplastic reaction in the NEBs of silica treated rats occurred only in alveolar NEBs, but not in bronchiolar NEBs. From Month 11 onwards, there were marked differences in the number of alveolar NEBs per section and in the number of cells per alveolar NEB immunoreactive for CGRP. No hyperplastic NE cell reaction was observed in silica-treated mice and hamsters. Significant PAMP and PAM expression was seen only in rat hyperplastic alveolar and in bronchiolar NEBs from Month 11 onwards. In E18, rat fetal lung NEBs were found to be strongly positive for PAMP and PAM.

Topics: Adrenomedullin; Amides; Animals; Cell Division; Cricetinae; Enzymes; Female; Fetus; Hyperplasia; Lung Neoplasms; Mesocricetus; Mice; Mice, Inbred Strains; Neurosecretory Systems; Peptide Fragments; Peptides; Protein Precursors; Proteins; Pulmonary Alveoli; Rats; Rats, Inbred F344; Reference Values; Silicon Dioxide

We investigated tamoxifen's effects on the expression of growth regulatory genes in the endometrium to identify the mechanism by which tamoxifen induces proliferation.. Using immunohistochemical techniques, we analyzed 39 endometrial specimens for expression of Ki-67, lactoferrin, transforming growth factor-alpha, tumor necrosis factor receptor-II, adrenomedullin, estrogen receptors, and progesterone receptors. Twenty specimens were obtained from postmenopausal breast cancer patients treated with tamoxifen (20 mg/day) for at least 6 months to include two endometrial adenocarcinoma specimens. Five secretory phase, three proliferative phase, and seven atrophic endometrial specimens were used as controls. In addition, four endometrial adenocarcinoma specimens were reviewed from patients not treated with tamoxifen. Intensity of immunostaining was quantified using digitized imaging techniques.. Overexpression of both estrogen receptors and progesterone receptors, and an elevated proliferative index were the most consistent effects observed in benign endometrial specimens from tamoxifen-treated patients compared with atrophic controls (P <. 003). This staining pattern was also evident in adenocarcinomas from patients who received tamoxifen. Benign endometrium from tamoxifen-treated patients also expressed transforming growth factor-alpha, tumor necrosis factor receptor-II, lactoferrin, and adrenomedullin at levels comparable with those found in proliferative endometrial specimens.. These data provide further documentation that the uterotropic effects of tamoxifen may be due, at least in part, to the induction of estrogen receptors and progesterone receptors, as well as other genes associated with the proliferative phase. Furthermore, analysis of estrogen receptors, progesterone receptors, and Ki-67 may be useful in identifying postmenopausal individuals on tamoxifen, who are at increased risk for developing endometrial cancer.

Topics: Adrenomedullin; Antineoplastic Agents, Hormonal; Breast Neoplasms; Endometrial Neoplasms; Endometrium; Female; Gene Expression Regulation, Neoplastic; Genes, Regulator; Humans; Hyperplasia; Immunohistochemistry; Ki-67 Antigen; Lactoferrin; Peptides; Receptors, Estrogen; Receptors, Progesterone; Receptors, Tumor Necrosis Factor; Tamoxifen; Transforming Growth Factor alpha