Abstract 522: TGF-beta Neutralization Augments Development of Angiotensin II-induced Aneurysms in Both Ascending and Abdominal Aortic Regions

Introduction and Objectives Angiotensin II (AngII) infusion induces ascending and abdominal aortic aneurysms (AAs) in mice. In a mouse model of Marfan Syndrome expressing Fbn1 C1039G/+ , ascending AAs were reduced by administration of a transforming growth factor-beta (TGF-beta) neutralizing antibody. In contrast, administration of TGF-beta neutralizing antibodies to AngII-infused mice increased aortic rupture. The purpose of this study was to compare the effects of TGF-beta neutralization on formation and progression of AngII-induced ascending and abdominal AAs. Methods and Results Male C57BL/6 mice were fed a normal diet and infused subcutaneously with AngII (1,000 ng/kg/min). Five days prior to initiating infusion, mice were injected i.p. with either a mouse monoclonal TGF-beta antibody (1D11) or an isotype matched IgG at a dose of either 0.3 or 5 mg/kg x 3/per week. 1D11 administration significantly decreased serum TGF-beta concentrations. TGF-beta neutralization at 5 mg/kg greatly increased the incidence of aortic rupture, which was attributed to rupture in both the ascending and abdominal regions. For mice that remained viable after 28 days of infusion, there were equivalent increases in aortic dilation in both the ascending and abdominal regions. Prior to rupture, aortic diameters determined by ultrasound demonstrated no significant effect on AngII-induced dilation of the ascending or abdominal aorta. We also studied the effects of TGF-beta neutralization in mice with established AngII-induced AAs following AngII-infusion for 28 days. C57BL/6 mice were injected with the mouse TGF-beta neutralizing antibody or IgG control (5 mg/kg x 3/per week, n=10 per group), while AngII infusion was continued for a further 28 days. Although TGF-beta antibody administration significantly decreased serum TGF-beta concentrations in mice with established AAs, there was no effect on aortic rupture or dilation of either the ascending or abdominal aortic region. Conclusion TGF-beta inhibition augmented AngII-induced aortic rupture in both the ascending and abdominal regions but had no effect on dilation. Furthermore, TGF-beta neutralization had no effect on either aortic rupture or expansion in established AAs.

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Abstract 283: Platelet Inhibition Increases Angiotensin II-induced Abdominal Aortic Aneurysm Incidence and Rupture in Mice

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.33.suppl_1.a283 ◽

2013 ◽

Vol 33 (suppl_1) ◽

Author(s):

A. Phillip Owens ◽

Yacine Boulaftali ◽

Wolfgang Bergmeier ◽

James P Luyendyk ◽

Nigel Mackman

Keyword(s):

Angiotensin Ii ◽

Mouse Model ◽

Milk Fat ◽

Aortic Rupture ◽

Plasma Cholesterol ◽

Dabigatran Etexilate ◽

Aortic Aneurysms ◽

Thrombin Inhibitor ◽

Drug Bioavailability ◽

Abdominal Aortic

Objective Platelets play a central role in both hemostasis and thrombosis. The coagulation protease thrombin activates platelets by cleavage of protease-activated receptors (PAR1 and PAR4 in humans, and PAR3 and PAR4 in mice). Circulating thrombin is increased in patients with abdominal aortic aneurysms (AAAs). We recently demonstrated that PAR4 deficiency in mice increased the incidence of aneurysm (P = 0.001) and rupture-induced death (P = 0.003) in an angiotensin II (AngII) infusion model of AAA. Furthermore, platelet depletion significantly increased rupture in this model (P = 0.048). The purpose of this study was to examine clinically used anti-platelet drugs in this mouse model of AAA. Methods and Results Male Ldlr -/- mice (8-12 weeks in age) were fed a fat and cholesterol-enriched diet (21% milk fat, 0.2% cholesterol). Groups of mice received either aspirin (30 mg/L via drinking water [ASA]), or diet supplemented with the direct thrombin inhibitor dabigatran etexilate (10 g/kg chow [DE]) or the P2Y 12 inhibitor clopidogrel (50 mg/kg/day [Plavix]) 1 week prior to and throughout AngII (1,000 ng/kg/min) infusion for 28 days. Drug bioavailability was confirmed with all treatments. Medial diameters in the suprarenal aortic region were increased significantly from baseline to day 28 in all groups infused with AngII, as measured by in vivo ultrasound. Medial diameters were not different in any of the treatment groups compared with placebo controls. However, DE (87% vs. 47%) and Plavix (82% vs. 40%) significantly increased the incidence of AAA versus placebo groups (P < 0.05). ASA also increased the incidence of AAA (93% vs. 70% P = NS). Importantly, all treatments had a significant increase in aortic rupture-induced death versus placebo groups (P < 0.05; DE [67% vs. 7%]; Plavix [41% vs. 0%]; and ASA [64% vs. 10%]). None of the treatments affected total plasma cholesterol, lipoprotein-cholesterol distributions, or AngII-induced increases in systolic blood pressure. Conclusion This study indicates that the presence of functional platelets reduces the formation and rupture of AAA in this mouse model. This suggests that inhibition of platelet function may be detrimental to patients with existing AAAs, a conclusion that will be addressed in future mouse studies.

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Basic FGF and TGF-beta 1 influence commitment to melanogenesis in neural crest-derived cells of avian embryos

Development ◽

10.1242/dev.111.2.635 ◽

1991 ◽

Vol 111 (2) ◽

pp. 635-645 ◽

Cited By ~ 5

Author(s):

K.M. Stocker ◽

L. Sherman ◽

S. Rees ◽

G. Ciment

Keyword(s):

Growth Factors ◽

Growth Factor ◽

Neural Crest ◽

Cell Fate ◽

Transforming Growth Factor Beta ◽

Culture Medium ◽

Transforming Growth Factor ◽

Neutralizing Antibody ◽

Pigment Cells ◽

Tgf Beta

In previous studies, we showed that neural crest (NC)-derived cells from embryonic quail dorsal root ganglia (DRG) and peripheral nerve (PN), which do not normally give rise to melanocytes, become committed to melanogenesis following treatment in culture with the phorbol ester drug 12-O-tetradecanoyl phorbol-13-acetate (TPA). These and other observations support the notion that melanocytes and Schwann cells are derived from a common bipotent intermediate in the neural crest lineage—the melanocyte/Schwann cell progenitor. In this study, we test the possibility that peptide growth factors found in the embryonic environment might act similarly to TPA to influence the fates of these cells. DRG and PN explants were cultured in medium supplemented with a variety of growth factors, and then the cultures were examined for the presence of pigment cells. We found that basic fibroblast growth factor (bFGF), but not various other growth factors, induced pigmentation in about 20% of these cultures. When low concentrations of TPA were included in the culture medium, bFGF augmented the TPA-induced pigmentation, significantly increasing the proportion of pigmented cultures. These effects of bFGF were age-dependent, and could be blocked by addition of a bFGF-neutralizing antibody to the culture medium. In contrast to these stimulatory effects of bFGF, transforming growth factor-beta 1 (TGF-beta 1) was found to inhibit the TPA- or bFGF-induced pigmentation of DRG cultures. These data suggest, therefore, that at least some NC-derived cells are responsive to bFGF and TGF-beta 1, and that these growth factors may play an important role in the control of NC cell fate.

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Human natural killer cell expansion is regulated by thrombospondin- mediated activation of transforming growth factor-beta 1 and independent accessory cell-derived contact and soluble factors

Blood ◽

10.1182/blood.v87.1.180.bloodjournal871180 ◽

1996 ◽

Vol 87 (1) ◽

pp. 180-189 ◽

Cited By ~ 4

Author(s):

BA Pierson ◽

K Gupta ◽

WS Hu ◽

JS Miller

Keyword(s):

Growth Factor ◽

Transforming Growth Factor Beta ◽

Direct Contact ◽

Transforming Growth Factor ◽

Neutralizing Antibody ◽

Accessory Cell ◽

Tgf Beta ◽

Soluble Factors ◽

Marrow Stroma ◽

Growth Factor Beta

Natural killer cells (NK) were studied to determine factors important in their expansion. Flourescence-activated cell sorter (FACS) purified CD56+/CD3- NK cells cultured alone for 18 days in rIL-2 containing medium (1,000 U/mL) showed enhanced cytotoxicity but only minimal expansion. NK expansion was increased (12.5 +/- 1.6-fold) by coculturing NK with soluble factors produced by irradiated peripheral blood mononuclear cells (PBMNC) in which the two populations were separated by a microporous membrane. However, maximal NK expansion was always observed when NK were cocultured in direct contact with irradiated PBMNC (49.4 +/- 5.9-fold). To determine if marrow stroma, which supports differentiation of primitive NK progenitors, was a better accessory cell population than irradiated PBMNC, NK were cocultured in direct contact with primary marrow stromal layers. NK expansion with marrow stroma was similar to PBMNC. Fibroblast cell lines (M2–10B4, NRK-49F, NIH-3T3) and human umbilical vein endothelial cells (HUVEC), all homogeneous populations and devoid of monocytes, also exhibited a similar contact-dependent increase in NK expansion. Experiments were designed using fixed M2–10B4 stromal cells to separate the contact-induced proliferative stimuli from soluble factors. NK plated directly on ethanol/acetic acid-fixed M2–10B4, which leaves stromal ligands (cell membrane components and ECM) intact, resulted in increased NK expansion compared with medium alone. We further show that the combination of independent contact and soluble factors is responsible for maximal late NK expansion (days 28 through 40) but paradoxically inhibits early NK expansion (day 7). The proliferation inhibitory effects were verified by 3H-thymidine uptake and could be detected at days 2 through 6 but no longer 14 days after the initiation of the culture. We show that both laminin and thrombospondin inhibit early NK proliferation, whereas only thrombospondin was capable of also stimulating late NK expansion. The effect of thrombospondin on early NK proliferation is related to activation of transforming growth factor-beta 1 (TGF-beta) because anti-TGF-beta neutralizing antibody completely abrogated thrombospondin-mediated inhibition of early NK proliferation. Although inhibitory early in culture, active TGF-beta added only at culture initiation increases late NK expansion similar to thrombospondin. TGF-beta was not present in the thrombospondin preparation but latent TGF-beta in serum, or TGF-beta transcripts identified in IL-2-activated NK could explain paracrine or autocrine mechanisms for the regulation of NK proliferation. Finally, anti-TGF-beta neutralizing antibody only minimally affects stroma-mediated inhibition of early NK proliferation suggesting that aside from thrombospondin/TGF-beta, additional contact factors are important for the regulation of NK proliferation.

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Transforming growth factor beta inhibits megakaryocyte growth and endomitosis

Blood ◽

10.1182/blood.v79.3.619.619 ◽

1992 ◽

Vol 79 (3) ◽

pp. 619-626 ◽

Cited By ~ 68

Author(s):

DJ Kuter ◽

DM Gminski ◽

RD Rosenberg

Keyword(s):

Growth Factor ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Potent Inhibitor ◽

Neutralizing Antibody ◽

Maximal Concentration ◽

Tgf Beta ◽

Inhibitory Effects ◽

Growth Factor Beta

Abstract Using a rat bone marrow culture system, the effect of transforming growth factor beta 1 (TGF beta 1) on megakaryocyte growth and endoreduplication has been studied. Purified human platelet TGF beta 1 inhibited the number of megakaryocytes that appeared in culture at a half-maximal concentration of 0.66 +/- 0.21 ng/mL and inhibited megakaryocyte endoreduplication at a half-maximal concentration of 0.14 +/- 0.08 ng/mL. Under identical conditions, growth of erythroid precursors was half-maximally inhibited at a concentration of 0.125 ng/mL while myeloid growth was not inhibited at concentrations of TGF beta 1 up to 25 ng/mL. These profound inhibitory effects on megakaryocyte growth and endomitosis suggested that TGF beta might play a role in megakaryocytopoiesis. Therefore, we explored the effect of TGF beta in three different experimental situations by using a neutralizing antibody to TGF beta: (1) Serum but not plasma was found to inhibit the number and ploidy of megakaryocytes that grew in vitro. This inhibitory activity was completely neutralized by antibody to TGF beta or on treatment with dithiothreitol. (2) Plasma from thrombocytotic rats was observed to decrease megakaryocyte ploidy on culture but this effect was not prevented by the addition of antibody to TGF beta. (3) Plasma from thrombocytopenic but not normal rats increased megakaryocyte ploidy on culture. Addition of antibody to TGF beta did not alter these results. Therefore, TGF beta is a potent inhibitor of the number and ploidy of megakaryocytes and accounts for all the inhibition seen when megakaryocytes are cultured in serum. However, the differences in effect on megakaryocyte growth that we observe between normal, thrombocytopenic, and thrombocytotic plasmas are not due to variations in the amount of TGF beta. Furthermore, our results show that release of TGF beta from megakaryocytes during culture does not act as an autocrine regulator of megakaryocyte ploidy in vitro.

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Abstract 86: Intercellular Adhesion Molecule 1 Deficiency Attenuated Angiotensin II--Induced Abdominal Aortic Aneurysms in Apolipoprotein E--Deficient Mice

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.34.suppl_1.86 ◽

2014 ◽

Vol 34 (suppl_1) ◽

Author(s):

Haruhito A Uchida ◽

Ryoko Umebayashi ◽

Yuki Kakio ◽

Kenichi Shikata ◽

Hirofumi Makino

Keyword(s):

Body Weight ◽

Angiotensin Ii ◽

Abdominal Aortic Aneurysms ◽

Normal Diet ◽

Aortic Aneurysms ◽

Intercellular Adhesion Molecule ◽

Intercellular Adhesion Molecule 1 ◽

Abdominal Aortic ◽

Deficient Mice ◽

Mini Pump

Objective: Chronic infusion of angiotensin II (AngII) augments the development of abdominal aortic aneurysms (AAAs) in hypercholesterolemic mice. Several studies have suggested that intercellular adhesion molecule 1 (ICAM-1) expression increases in association with AAA formation. The aim of the study was to define whether ICAM deficiency influenced AngII-induced AAA formation. Methods and Results: Apolipoprotein E deficient (apoE -/-) mice were cross-bred with ICAM-1 deficient mice. Male apoE -/- mice fed a normal diet and infused subcutaneously with saline or AngII (1,000 ng/kg/min) via osmotic mini pump for 1 week. AngII infusion increased aortic ICAM-1 protein. Male apoE -/- mice that were either ICAM-1 +/+ or -/- were fed a normal diet and infused subcutaneously with AngII (1,000 ng/kg/min) via osmotic mini pump for 4 weeks. Total ICAM-1 deficiency had no significant effect on body weight, total cholesterol concentrations, or systolic blood pressures prior to and during AngII infusion. AngII induced expansion of ex vivo maximal diameters of abdominal aortas was attenuated significantly in ICAM-1 deficient mice (ICAM-1 +/+, 1.78 ± 0.20 mm; ICAM-1 -/-, 1.07 ± 0.03 mm, P < 0.0001). ICAM-1 deficiency also reduced significantly the incidence of AngII-induced AAAs (ICAM-1 +/+, 76%; ICAM-1 -/-, 13%, P < 0.0001). Furthermore, bone-marrow transplantation was performed to develop chimeric mice that were ICAM-1 +/+ or -/- in donor cells and ICAM-1 +/+ or -/- in recipient cells. ICAM-1 deficiency in either donor or recipient cells had no effect on body weight, total cholesterol concentrations, or systolic blood pressure. Recipient ICAM-1 deficiency significantly attenuated the incidence of AngII-induced AAA formation (ICAM-1 +/+, 67%; ICAM-1 -/-, 19%, P = 0.0008). Furthermore, lack of ICAM-1 reduced AngII-induced aortic MMP-2 activation (P < 0.05). Conclusion: ICAM-1 deficiency attenuated AngII-induced AAAs in male apoE -/- mice.

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Systemic delivery of targeted nanotherapeutic reverses angiotensin II-induced abdominal aortic aneurysms in mice

Scientific Reports ◽

10.1038/s41598-021-88017-w ◽

2021 ◽

Vol 11 (1) ◽

Author(s):

Xiaoying Wang ◽

Vaideesh Parasaram ◽

Saphala Dhital ◽

Nasim Nosoudi ◽

Shahd Hasanain ◽

...

Keyword(s):

Angiotensin Ii ◽

Cause Of Death ◽

Targeted Delivery ◽

Aortic Rupture ◽

Aortic Aneurysms ◽

Systemic Delivery ◽

Effective Treatment Option ◽

Abdominal Aortic ◽

Pentagalloyl Glucose ◽

Elastic Lamina

AbstractAbdominal aortic aneurysm (AAA) disease causes dilation of the aorta, leading to aortic rupture and death if not treated early. It is the 14th leading cause of death in the U.S. and 10th leading cause of death in men over age 55, affecting thousands of patients. Despite the prevalence of AAA, no safe and efficient pharmacotherapies exist for patients. The deterioration of the elastic lamina in the aneurysmal wall is a consistent feature of AAAs, making it an ideal target for delivering drugs to the AAA site. In this research, we conjugated nanoparticles with an elastin antibody that only targets degraded elastin while sparing healthy elastin. After induction of aneurysm by 4-week infusion of angiotensin II (Ang II), two biweekly intravenous injections of pentagalloyl glucose (PGG)-loaded nanoparticles conjugated with elastin antibody delivered the drug to the aneurysm site. We show that targeted delivery of PGG could reverse the aortic dilation, ameliorate the inflammation, restore the elastic lamina, and improve the mechanical properties of the aorta at the AAA site. Therefore, simple iv therapy of PGG loaded nanoparticles can be an effective treatment option for early to middle stage aneurysms to reverse disease progression and return the aorta to normal homeostasis.

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Transforming growth factor beta inhibits megakaryocyte growth and endomitosis

Blood ◽

10.1182/blood.v79.3.619.bloodjournal793619 ◽

1992 ◽

Vol 79 (3) ◽

pp. 619-626 ◽

Cited By ~ 2

Author(s):

DJ Kuter ◽

DM Gminski ◽

RD Rosenberg

Keyword(s):

Growth Factor ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Potent Inhibitor ◽

Neutralizing Antibody ◽

Maximal Concentration ◽

Tgf Beta ◽

Inhibitory Effects ◽

Growth Factor Beta

Using a rat bone marrow culture system, the effect of transforming growth factor beta 1 (TGF beta 1) on megakaryocyte growth and endoreduplication has been studied. Purified human platelet TGF beta 1 inhibited the number of megakaryocytes that appeared in culture at a half-maximal concentration of 0.66 +/- 0.21 ng/mL and inhibited megakaryocyte endoreduplication at a half-maximal concentration of 0.14 +/- 0.08 ng/mL. Under identical conditions, growth of erythroid precursors was half-maximally inhibited at a concentration of 0.125 ng/mL while myeloid growth was not inhibited at concentrations of TGF beta 1 up to 25 ng/mL. These profound inhibitory effects on megakaryocyte growth and endomitosis suggested that TGF beta might play a role in megakaryocytopoiesis. Therefore, we explored the effect of TGF beta in three different experimental situations by using a neutralizing antibody to TGF beta: (1) Serum but not plasma was found to inhibit the number and ploidy of megakaryocytes that grew in vitro. This inhibitory activity was completely neutralized by antibody to TGF beta or on treatment with dithiothreitol. (2) Plasma from thrombocytotic rats was observed to decrease megakaryocyte ploidy on culture but this effect was not prevented by the addition of antibody to TGF beta. (3) Plasma from thrombocytopenic but not normal rats increased megakaryocyte ploidy on culture. Addition of antibody to TGF beta did not alter these results. Therefore, TGF beta is a potent inhibitor of the number and ploidy of megakaryocytes and accounts for all the inhibition seen when megakaryocytes are cultured in serum. However, the differences in effect on megakaryocyte growth that we observe between normal, thrombocytopenic, and thrombocytotic plasmas are not due to variations in the amount of TGF beta. Furthermore, our results show that release of TGF beta from megakaryocytes during culture does not act as an autocrine regulator of megakaryocyte ploidy in vitro.

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Abstract 617: Phenotype as a Basis for Selection of BM-MSC-Derived SMCs for Regenerative Repair of Abdominal Aortic Aneurysms

Arteriosclerosis Thrombosis and Vascular Biology ◽

10.1161/atvb.35.suppl_1.617 ◽

2015 ◽

Vol 35 (suppl_1) ◽

Author(s):

Ganesh Swaminathan ◽

Ivan Stoilov ◽

Ian Bratz ◽

Robert P Mecham ◽

Anand Ramamurthi

Keyword(s):

Growth Factor ◽

Cell Therapy ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Abdominal Aortic Aneurysms ◽

The Elderly ◽

Aortic Aneurysms ◽

Elastic Matrix ◽

Abdominal Aortic ◽

Regenerative Repair

Abdominal aortic aneurysms (AAA) are a leading cause of death in the elderly with over 150,000 new diagnoses annually in the US. They involve bulging of the abdominal aorta due to chronic proteolytic degradation of the wall structural extracellular matrix (ECM), mainly elastin and collagen. There are currently no established medical management approaches for treating small AAAs and early surgical intervention provides no benefit. AAA growth arrest and regression are also prevented by inherently poor auto regenerative repair of elastic matrix by adult vascular smooth muscle cells (SMCs). We have identified bone marrow mesenchymal stem cell-derived SMCs (BM-SMCs) as superior cell types for regenerative cell therapy due to their high elastogenicity and pro-elastogenic and anti-proteolytic effects on AAA SMCs. In this study we investigated if and how phenotypic coordinates of BM-SMCs on a contractile to synthetic phenotypic continuum impact their above functional benefits. BM-SMC subpopulations were generated under 2% & 10% v/v FBS conditions in presence of transforming growth factor beta-1 (TGFβ), with or without platelet derived growth factor (PDGF-BB) under low & high glucose conditions. Phenotypic coordinates of the BM-SMCs were established by analysis of SMC marker (alpha SM actin (αSMA), SM22, caldesmon, smoothelin, MHC) expression with RT-PCR, western blotting, and immunofluorescence (IF) staining. Elastogenicities of the cell subpopulations were compared by analysis of tropoelastin and matrix elastin synthesis (Fastin assay), crosslinking (ELISA for desmosine), IF, and TEM; contractile properties were compared via a carbachol assay and whole cell patch-clamp for intracellular Ca 2+ /K + activity. Overall, our results indicate that 10% FBS + TGF with/without PDGF express higher contractile markers and higher elastic matrix yield when compared to controls (aortic SMCs and MSCs) and other test cases. Together with ongoing studies that are evaluating pro-elastogenic and anti-proteolytic effects of our generated BM-SMCs on AAA SMCs in non-contact coculture, we believe that the results are promising towards identifying superior elastogenic cell sources for a regenerative cell therapy for AAAs, which we are validating in a rat AAA model.

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Requirement for transglutaminase in the activation of latent transforming growth factor-beta in bovine endothelial cells.

The Journal of Cell Biology ◽

10.1083/jcb.121.2.439 ◽

1993 ◽

Vol 121 (2) ◽

pp. 439-448 ◽

Cited By ~ 201

Author(s):

S Kojima ◽

K Nara ◽

D B Rifkin

Keyword(s):

Endothelial Cells ◽

Growth Factor ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Direct Action ◽

Neutralizing Antibody ◽

Activation Process ◽

Type Ii ◽

Tgf Beta ◽

Growth Factor Beta

A hitherto unknown function for transglutaminase (TGase; R-glutaminyl-peptide: amine gamma-glutamyltransferase, EC 2.3.2.13) was found in the conversion of latent transforming growth factor-beta (LTGF-beta) to active TGF-beta by bovine aortic endothelial cells (BAECs). The cell-associated, plasmin-mediated activation of LTGF-beta to TGF-beta induced either by treatment of BAECs with retinoids or by cocultures of BAECs and bovine smooth muscle cells (BSMCs) was blocked by seven different inhibitors of TGase as well as a neutralizing antibody to bovine endothelial cell type II TGase. Control experiments indicated that TGase inhibitors and/or a neutralizing antibody to TGase did not interfere with the direct action of TGF-beta, the release of LTGF-beta from cells, or the activation of LTGF-beta by plasmin or by transient acidification. After treatment with retinoids, BAECs expressed increased levels of TGase coordinate with the generation of TGF-beta, whereas BSMCs and bovine embryonic skin fibroblasts, which did not activate LTGF-beta after treatment with retinoids, did not. Furthermore, both TGase inhibitors and a neutralizing antibody to TGase potentiated the effect of retinol in enhancing plasminogen activator (PA) levels in cultures of BAECs by suppressing the TGF-beta-mediated enhancement of PA inhibitor-1 (PAI-1) expression. These results indicate that type II TGase is a component required for cell surface, plasmin-mediated LTGF-beta activation process and that increased expression of TGase accompanies retinoid-induced activation of LTGF-beta.

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Trophic effects of angiotensin II on neonatal rat cardiac myocytes are mediated by cardiac fibroblasts

AJP Endocrinology and Metabolism ◽

10.1152/ajpendo.1995.269.3.e426 ◽

1995 ◽

Vol 269 (3) ◽

pp. E426-E437 ◽

Cited By ~ 12

Author(s):

N. N. Kim ◽

F. J. Villarreal ◽

M. P. Printz ◽

A. A. Lee ◽

W. H. Dillmann

Keyword(s):

Angiotensin Ii ◽

Transforming Growth Factor Beta ◽

Transforming Growth Factor ◽

Specific Binding ◽

Cardiac Fibroblasts ◽

Critical Role ◽

Neonatal Rat ◽

Ang Ii ◽

Tgf Beta ◽

Trophic Effects

Cultured neonatal rat cardiac fibroblasts (NF) and myocytes (NM) were used to examine the distribution of angiotensin II (ANG II) receptors and the potential role of NF in mediating the trophic response to ANG II in the heart. In NM preparations cultured for 2-5 days, specific binding to 125I-ANG II was < 10% of the specific binding in cultured NF. Binding assays, immunocytochemistry, and autoradiography in NM cultured for > 5 days identified two populations of cells, one with fibroblast-like morphology and high density of ANG II receptors and another with low binding, comparable to NM cultures at day 5 or earlier. Conditioned medium (CM) from untreated NF increased cell surface area and net [3H]leucine (Leu) incorporation 1.4-fold in NM. CM from ANG II-treated NF enhanced [3H]Leu incorporation 2.2-fold in NM. This potentiating effect of ANG II was inhibited by losartan and was absent when ANG II was added directly to NM. In addition, studies using antibodies and bioassay for transforming growth factor-beta 1 (TGF-beta 1) suggested that TGF-beta 1 does not mediate the trophic effects of ANG II on NM. We conclude that ANG II receptors are localized predominantly on NF and that ANG II can indirectly stimulate hypertrophy of NM by stimulating NF to produce a transferrable factor(s). These data suggest that cardiac fibroblasts may play a critical role in mediating the hypertrophic response to ANG II in the rat heart.

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