Stimulation of adhesion molecule expression in human endothelial cells (HUVEC) by adrenomedullin and corticotrophin

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.

The role of angiotensin II in cancer metastasis: Potential of renin-angiotensin system blockade as a treatment for cancer metastasis

Hypertension, which often exists as a comorbid condition in cancer patients, is considered as a factor affecting cancer progression. The renin-angiotensin system (RAS) plays an important role in the regulation of blood pressure, and angiotensin II (Ang II) is a well-known pressor peptide in RAS. There is also accumulated evidence indicating that Ang II plays a critical role in the metastasis of various cancers by modulating adhesion, migration invasion, proliferation, and angiogenesis. Consistent with this, large epidemiological studies have reported the potential beneficial effects of angiotensin-converting enzyme (ACE) inhibitors and Ang II type 1 receptor blockers (ARBs) against cancer metastasis; however, some of the results remain controversial. Although the precise Ang II-related mechanisms involved in cancer metastasis are not completely clear yet, a number of basic and meta-analytic studies have shown that ACE inhibitors and ARBs reduce the metastatic potential of tumors. In this review, we summarize the relationships among hypertension, RAS, and metastasis as demonstrated in basic and clinical studies. Finally, we discuss the possibility of using RAS inhibitors as anti-metastatic drugs.

Adrenomedullin promotes the growth of pancreatic ductal adenocarcinoma through recruitment of myelomonocytic cells

Stromal infiltration of myelomonocytic cells is a hallmark of pancreatic ductal adenocarcinoma (PDAC) and is related to a poor prognosis. However, the detailed mechanism for the recruitment of myelomonocytic cells to pancreatic cancer tissue remains unclear. In the present study, pancreatic cancer cells secreted high levels of adrenomedullin (ADM), and CD11b⁺ myelomonocytic cells expressed all components of ADM receptors, including GPR182, CRLR, RAMP2 and RAMP3. ADM enhanced the migration and invasion of myelomonocytic cells through activation of the MAPK, PI3K/Akt and eNOS signaling pathways, as well as the expression and activity of MMP-2. ADM also promoted the adhesion and trans-endothelial migration of myelomonocytic cells by increasing expression of VCAM-1 and ICAM-1 in endothelial cells. In addition, ADM induced macrophages and myeloid-derived suppressor cells (MDSCs) to express pro-tumor phenotypes. ADM knockdown in tumor-bearing mice or administration of AMA, an ADM antagonist, significantly inhibited the recruitment of myelomonocytic cells and tumor angiogenesis. Moreover, in vivo depletion of myelomonocytic cells using clodronate liposomes suppressed the progression of PDAC. These results reveal a novel function of ADM in PDAC, and suggest ADM is a promising target in the treatment of PDAC.

Repetitive hypoglycaemia increases serum adrenaline and induces monocyte adhesion to the endothelium in rat thoracic aorta

AIMS/HYPOTHESIS

Severe hypoglycaemia associated with diabetes management is a potential risk for cardiovascular diseases. However, the effect and mechanism of hypoglycaemia on the progression of atherosclerosis remains largely unknown. As a first step towards elucidating the above, we investigated the effect of hypoglycaemia on monocyte-endothelial interaction.

METHODS

Insulin was injected intraperitoneally once every 3 days for 5 weeks in Goto-Kakizaki rats, a non-obese rat model of type 2 diabetes. We counted the number of monocytes adherent to the endothelium of thoracic aorta as an index of early atherosclerogenesis. Cultured HUVEC were used to investigate the mechanism of action.

RESULTS

Insulin treatment increased the number of monocytes adherent to the vascular endothelium. This increase was abrogated by injection of glucose with insulin. Amosulalol, an α-1 and β-adrenoreceptor antagonist, suppressed monocyte adhesion to endothelium and levels of adhesion molecules (intercellular adhesion molecule-1 and vascular cell adhesion molecule-1) in the endothelial surface, which had been enhanced by insulin-induced hypoglycaemia. In HUVEC, adrenaline (epinephrine) significantly increased nuclear translocation of nuclear factor-κB (NF-κB) p65 and levels of adhesion molecules, effects that were abrogated following addition of SQ22536, a specific adenyl cyclase inhibitor.

CONCLUSIONS/INTERPRETATION

Our data indicate that repetitive hypoglycaemia induced by insulin enhanced monocyte adhesion to endothelial cells in Goto-Kakizaki rat aorta through enhanced adrenaline activity and that the latter stimulated intracellular cAMP, leading to nuclear translocation of NF-κB with subsequent production of adhesion molecules in endothelial cells.

Adrenomedullin increases fibroblast-like synoviocyte adhesion to extracellular matrix proteins by upregulating integrin activation

Introduction

Rheumatoid arthritis (RA) is characterized by bone and cartilage invasion by fibroblast-like synoviocytes (FLSs). Adrenomedullin, a peptide with anabolic and antiapoptotic properties, is secreted by rheumatoid FLSs. Adrenomedullin also increases the expression of adhesion molecules in endothelial cells and keratinocytes. Here, we investigated whether adrenomedullin mediated FLS adhesion to extracellular matrix (ECM) proteins.

Methods

FLSs were isolated from synovial tissues from RA and osteoarthritis (OA) patients. Plates were coated overnight with the ECM proteins vitronectin, fibronectin, and type I collagen (Coll.I). Adrenomedullin was used as a soluble FLS ligand before plating. We tested interactions with the adrenomedullin receptor antagonist (22-52)adrenomedullin and with the protein kinase A (PKA) inhibitor H-89, and inhibition of co-receptor RAMP-2 by siRNA. Cell adhesion was measured by using color densitometry. Activation of α₂ and β₁ integrins was evaluated by fluorescent microscopy; integrin inhibition, by RGD peptides; and the talin-integrin interaction, by immunoprecipitation (IP).

Results

Adrenomedullin specifically increased RA-FLS adhesion to vitronectin, fibronectin, and Coll.I; no such effect was found for OA-FLS adhesion. Basal or adrenomedullin-stimulated RA-FLS adhesion was inhibited by (22-52)adrenomedullin, H-89, and RAMP-2 siRNA. Adrenomedullin-stimulated adhesion was inhibited by RGD peptides, and associated with α₂ and β₁ integrin activation. This activation was shown with IP to be related to an integrin-talin interaction and was significantly decreased by (22-52)adrenomedullin.

Conclusions

Adrenomedullin-stimulated RA-FLS adhesion was specific for ECM proteins and mediated by α₂ and β₁ integrins. This effect of adrenomedullin was dependent on adrenomedullin receptors. These results support a new role for adrenomedullin in rheumatoid synovial fibroblast pathobiology.

Adrenomedullin reduces expression of adhesion molecules on lymphatic endothelial cells

Adrenomedullin (AM) is a novel vasoactive peptide which regulates vascular tone and vascular endothelial cell growth. We recently reported that lymphatic endothelial cells (LECs) are also an attractive target of AM and concluded that AM is a potent mediator of lympangiogenesis. In the present study, we conducted a genome-wide analysis of genes that are regulated by AM in LECs. AM profoundly suppressed gene expression of cell adhesion receptors and inflammatory factors in LECs, such as intercellular adhesion molecule-1 (ICAM-1), vascular adhesion molecule-1 (VCAM-1), endothelial adhesion molecule-1 (E-selectin), interleukin-8, and chemokines, QRT-PCR and flow cytometry analysis showed that AM dose-dependently suppressed the TNF-a-induced mRNA and protein expression of ICAM-1 and VCAM-l. Treatment of LECs with a cell permeable cyclic adenosine monophosphate (cAMP) analog, 8-Br-cAMP, mimicked the suppressive effect of AM on the expression of adhesion molecules. Moreover, both AM and 8-Br-cAMP suppressed TNF-α-induced NF-κB activation in LECs, indicating that AM reduces expression of adhesion molecules in LECs via a cAMP/NF-kB dependent pathway. These results suggest that AM may have an important role in the regulation of the expression of adhesion molecules in lymphatic endothelium, which is critical in the control of immune and inflammatory responses.

Stachydrine, a major constituent of the Chinese herb leonurus heterophyllus sweet, ameliorates human umbilical vein endothelial cells injury induced by anoxia-reoxygenation

Stachydrine is a major constituent of Chinese herb leonurus heterophyllus sweet, which is used in clinics to promote blood circulation and dispel blood stasis. Our study aimed to investigate the role of stachydrine in human umbilical vein endothelial cells (HUVECs) injury induced by anoxia-reoxygenation. Cultured HUVECs were divided randomly into control group, anoxia-reoxygenation (A/R) group and 4 A/R+stachydrine groups. HUVECs in the control group were exposed to normoxia for 5 hours, while in all A/R groups, HUVECs underwent 3 hours anoxia followed by 2 hours reoxygenation, and HUVECs in the 4 A/R+stachydrine groups were treated with 10(-8) M, 10(-7) M, 10(-6) M and 10(-5) M (final concentration) of stachydrine respectively. After anoxia-reoxygenation, tissue factor (TF) was over-expressed, cell viability and the concentrations of SOD, GSH-PX and NO were declined, while LDH, MDA and ET-1 were over-produced (p < 0.05 to 0.001 vs. the control group). However, in stachydrine treated groups, TF expression was inhibited at both mRNA and protein levels, while the declined cell viability and SOD, GSH-PX, NO as well as the enhanced LDH, MDA and ET-1 levels occurred during anoxia-reoxygenation were ameliorated and reversed effectively (p < 0.05 to 0.01 versus A/R group). Consequently, our findings indicate that TF plays an important role in the development of anoxia-reoxygenation injury of HUVECs, stachydrine ameliorates HUVECs injury induced by anoxia-reoxygenation and its putative mechanisms are related to inhibition of TF expression.

Type I collagen inhibits differentiation and promotes a stem cell-like phenotype in human colorectal carcinoma cells

Background:

Human colorectal cancer is caused by mutations and is thought to be maintained by a population of cancer stem cells. Further phenotypic changes occurring at the invasive edge suggest that colon cancer cells are also regulated by their microenvironment. Type I collagen, a promoter of the malignant phenotype in pancreatic carcinoma cells, is highly expressed at the invasive front of human colorectal cancer.

Methods:

This study investigates the role of type I collagen in specifying the colorectal cancer cell phenotype. The effect of type I collagen on morphology, localisation of cell–cell adhesion proteins, differentiation and stem cell-like characteristics was examined in a panel of human colorectal carcinoma cell lines.

Results:

Human colorectal carcinoma cells grown on type I collagen in serum-free medium show an epithelial–mesenchymal-like transition (EMT-like), assuming a more flattened less cohesive morphology. Type I collagen downregulates E-cadherin and β-catenin at cell–cell junctions. Furthermore, type I collagen inhibits differentiation, increases clonogenicity and promotes expression of stem cell markers CD133 and Bmi1. Type I collagen effects were partially abrogated by a function-blocking antibody to α2 integrin.

Conclusion:

Together, these results indicate that type I collagen promotes expression of a stem cell-like phenotype in human colorectal cancer cells likely through α2β1 integrin.

Liposomal glucocorticoids as tumor-targeted anti-angiogenic nanomedicine in B16 melanoma-bearing mice

This study evaluates whether the inhibitory effects of prednisolone phosphate (PLP) encapsulated in long-circulating liposomes (LCL-PLP) on tumor growth and tumor angiogenesis described previously can be generalized to other types of glucocorticoids (GC) encapsulated in LCL (LCL-GC). Four types of synthetic GC, i.e. budesonide disodium phosphate (BUP), dexamethasone disodium phosphate (DXP), methylprednisolone disodium phosphate (MPLP), and PLP, were selected based on the difference in their potency to activate the human glucocorticoid receptor. The effects of all LCL-GC on the production of angiogenic/inflammatory factors in vivo in the B16.F10 murine melanoma model as well as on the viability and proliferation of tumor cells and endothelial cells in vitro were investigated. Our results show that all four selected LCL-GC formulations inhibit tumor growth, albeit to different degrees. The differences in antitumor activity of LCL-GC correlate with their efficacy to suppress tumor angiogenesis and inflammation. The strongest antitumor effect is achieved by LCL-encapsulated BUP (LCL-BUP), due to the highest potency of BUP versus the other three GC types. The in vitro results presented herein suggest that LCL-BUP has strong cytotoxic effects on B16.F10 melanoma cells and the anti-proliferative effects of all LCL-GC towards angiogenic endothelial cells play a role in their antitumor activity.

Effect of nasal continuous positive airway pressure treatment on plasma adrenomedullin levels in patients with obstructive sleep apnea syndrome: roles of nocturnal hypoxia and oxidant stress

Obstructive sleep apnea syndrome (OSAS) is recognized as one of the risk factors of hypertension and cardiovascular disorders. In the current study, we hypothesized that the hypoxic stress and oxidative stress caused by obstructive sleep apnea would increase circulating adrenomedullin (ADM) levels in untreated OSAS patients as compared to an age and body mass index (BMI)-matched control group and an age-matched, but normal-BMI control group. We further hypothesized that nasal continuous positive airway pressure (nCPAP) treatment may decrease OSAS-induced hypoxic stress, oxidative stress and ADM levels. To examine these hypotheses, we measured circulating ADM and reactive oxygen species (ROS) from leukocytes before and after nCPAP therapy in OSAS patients. The circulating levels of ADM and amount of ROS in untreated OSAS patients were significantly greater than those in the controls. No differences in ADM levels were found between the increased-BMI controls and normal-BMI controls. We observed that nCPAP treatment decreased sleep apneas, nocturnal oxyhemoglobin desaturation, the circulating ADM, and ROS production by leukocytes in OSAS patients. The ADM levels were associated with the magnitude of oxyhemoglobin desaturation rather than the number of sleep apneas. These observations suggest that nCPAP therapy could reduce OSAS-induced nocturnal hypoxemia, generation of ROS, and ADM in patients with OSAS.

Protective Effects of Sasanquasaponin on Injury of Endothelial Cells Induced by Anoxia and Reoxygenation in vitro

The protective effects of sasanquasaponin, an effective compound from Chinese traditional herbs, on ischaemia and reperfusion injury in mouse hearts have been suggested through modulation of intracellular Cl(-) homeostasis. The effects of sasanquasaponin on injury of endothelial cells, however, induced by anoxia and reoxygenation remain unknown. Therefore, the present study attempted to observe the effects of sasanquasaponin on anoxia and reoxygenation injury in endothelial cells and investigate its putative mechanisms. Human umbilical vein endothelial cells (HUVECs) were exposed to normoxia or anoxia and reoxygenation in the absence or presence of sasanquasaponin (10.0, 1.0 and 0.1 micromol/l). Lactate dehydrogenase activity was determined in cultured HUVECs supernatant, and malondialdehyde content, superoxide dismutase and glutathione peroxidase activities were measured in HUVECs by a colorimetric method. Neutrophil adhesion to HUVECs was assayed colorimetrically. The levels of intercellular adhesion molecule-1 and tumour necrosis factor-alpha were detected. The activity of nuclear factor kappa B was determined by flow cytometry. The results show that sasanquasaponin decreased the lactate dehydrogenase activity and malondialdehyde contents, and inhibited the neutrophil adhesion to HUVECs; sasanquasaponin, moreover, inhibited nuclear factor kappa B transnuclear activity, lowered tumour necrosis factor-alpha and intercellular adhesion molecule-1 expression levels. On the other hand, sasanquasaponin increased the mitochondrial superoxide dismutase and glutathione peroxidase activities. It is suggested that sasanquasaponin could protect HUVECs against anoxia and reoxygenation injury, and the protective mechanisms appear to be related to anti-lipoperoxidation and anti-adhesion.

Diet-induced Obesity Alters AMP Kinase Activity in Hypothalamus and Skeletal Muscle

AMP-activated protein kinase (AMPK) is a key regulator of cellular energy balance and of the effects of leptin on food intake and fatty acid oxidation. Obesity is usually associated with resistance to the effects of leptin on food intake and body weight. To determine whether diet-induced obesity (DIO) impairs the AMPK response to leptin in muscle and/or hypothalamus, we fed FVB mice a high fat (55%) diet for 10-12 weeks. Leptin acutely decreased food intake by approximately 30% in chow-fed mice. DIO mice tended to eat less, and leptin had no effect on food intake. Leptin decreased respiratory exchange ratio in chow-fed mice indicating increased fatty acid oxidation. Respiratory exchange ratio was low basally in high fat-fed mice, and leptin had no further effect. Leptin (3 mg/kg intraperitoneally) increased alpha2-AMPK activity 2-fold in muscle in chow-fed mice but not in DIO mice. Leptin decreased acetyl-CoA carboxylase activity 40% in muscle from chow-fed mice. In muscle from DIO mice, acetyl-CoA carboxylase activity was basally low, and leptin had no further effect. In paraventricular, arcuate, and medial hypothalamus of chow-fed mice, leptin inhibited alpha2-AMPK activity but not in DIO mice. In addition, leptin increased STAT3 phosphorylation 2-fold in arcuate of chow-fed mice, but this effect was attenuated because of elevated basal STAT3 phosphorylation in DIO mice. Thus, DIO in FVB mice alters alpha2-AMPK in muscle and hypothalamus and STAT3 in hypothalamus and impairs further effects of leptin on these signaling pathways. Defective responses of AMPK to leptin may contribute to resistance to leptin action on food intake and energy expenditure in obese states.

Competitive Binding of CREB and ATF2 to cAMP/ATF Responsive Element Regulates eNOS Gene Expression in Endothelial Cells

OBJECTIVE

Expression of endothelial nitric oxide synthase (eNOS) is a critical determinant for vascular homeostasis. We examined the effects of Beraprost sodium (BPS), a stable analogue of prostacyclin, on the eNOS gene expression in the presence of inflammatory cytokine interleukin (IL)-1beta in cultured endothelial cells.

METHOD AND RESULTS

Exposure of human and bovine endothelial cells to IL-1beta decreased eNOS expression. Western blot analysis using phospho-specific antibodies showed that IL-1beta stimulated p38 MAP kinase and phosphorylated ATF2. BPS inhibited these effects via protein kinase A (PKA)/cAMP-responsive element binding protein (CREB) activation. Transfection assays using site-specific mutation constructs showed that CRE/ATF elements located at -733 and -603 within the human eNOS promoter are necessary for full IL-1beta responsiveness. BPS attenuated the IL-1beta-mediated decrease in eNOS promoter activity and the expression of eNOS gene through PKA pathway. Electrophoretic gel mobility shift assays showed that IL-1beta increased the binding of phosphorylated ATF2 to CRE/ATF. On treatment with BPS, phosphorylated CREB predominantly bound to CRE/ATF.

CONCLUSIONS

These results indicate that IL-1beta and BPS antagonistically regulates the eNOS expression through the activation of p38 and PKA, respectively. Furthermore, the ability to bind both CREB and ATF2 implicates the CRE/ATF sequence as a potential target for multiple signaling pathways in the regulation of the eNOS gene transcription.

Adrenomedullin: molecular mechanisms and its role in cardiac disease

Adrenomedullin (AM) is a potent, long-lasting vasoactive peptide originally isolated from human pheochromocytoma. Since its discovery, serum and tissue AM expression have been shown to be increased in experimental models and in patients with cardiac hypertrophy, myocardial infarction and end-stage heart failure with several beneficial effects. Considerable evidence exists for a wide range of autocrine, paracrine and endocrine mechanisms for AM which include vasodilatory, anti-apoptotic, angiogenic, anti-fibrotic, natriuretic, diuretic and positive inotropic. Thus, through regulation of body fluid or direct cardiac mechanisms, AM has additive and beneficial effects in the context of heart disease. Notable molecular mechanisms of AM include cyclic adenosine monophosphate, guanosine-3',5'-monophosphate, PI3K/Akt and MAPK-ERK-mediated cascades. Given the endogenous and multifunctional nature of AM, we consider this molecule to have great potential in the treatment of cardiovascular diseases. In agreement, early experimental and preliminary clinical studies suggest that AM is a new and promising therapy for cardiovascular diseases.

Differentiation of the HaCaT keratinocyte cell line: modulation by adrenomedullin

BACKGROUND

Adrenomedullin (AM) is a multifunctional peptide produced by a wide variety of cells, including keratinocytes. We, and others, have demonstrated that AM has a role as a growth regulatory factor of the skin and contributes as an antimicrobial agent in the integument's protective barrier. It is not known whether AM has a role in differentiating keratinocytes.

OBJECTIVES

To study the role of AM in keratinocyte differentiation, modulating the effects of calcium and in addition, to assess whether differentiated keratinocytes are still capable of initiating an inflammatory response.

METHODS

HaCaT cells were differentiated using CaCl2. Expression of transglutaminase type 1 (TG1) and E2F1 genes was used to monitor differentiation. AM secretion was measured by enzyme-linked immunosorbent assay (ELISA). NF-kappaB activity and interleukin (IL)-6 secretion in the cells were assessed after exposure to calcium and AM by electrophoretic mobility shift assay and ELISA, respectively.

RESULTS

Secretion of AM by the keratinocyte cell line HaCaT was found to be increased during 1 mmol L(-1) CaCl2-induced cell differentiation but not 0.1 mmol L(-1) CaCl2. All treatments showed low levels of the cell proliferation marker, E2F1. Over time, cells incubated in the presence of 0.1 mmol L(-1) or 1 mmol L(-1) of CaCl2 showed an increase in TG1 expression, a marker of early differentiation. The addition of AM showed a decrease in TG1 expression when combined with 0.1 mmol L(-1) CaCl2, but not with 1 mmol L(-1) CaCl2. In addition, cells kept in 0.1 mmol L(-1) CaCl2 showed translocation of NF-kappaB after 48 h and 72 h of incubation, which was abolished when AM was added to the cells. Treatment with 1 mmol L(-1) CaCl2 led to earlier translocation of NF-kappaB at 24 h after treatment and addition of AM did not abolish the effect of 1 mmol L(-1) CaCl2 on NF-kappaB activation. Cells incubated in 0.1 mmol L(-1) CaCl2 showed increased secretion of IL-6 over time, consistent with NF-kappaB activation. The addition of AM to cells incubated with 0.1 mmol L(-1) CaCl2 showed a rapid decrease in IL-6 secretion after only 6 h. However, 1 mmol L(-1) CaCl2 did not induce secretion of IL-6 and the addition of AM did not affect the result.

CONCLUSIONS

Our data indicate that AM can reverse calcium-induced differentiation when 0.1 mmol L(-1) CaCl2 is used but not 1 mmol L(-1) CaCl2. Cells differentiated with 0.1 mmol L(-1) CaCl2 are still capable of generating an inflammatory response, showing signs of late NF-kappaB activation and IL-6 secretion that can be inhibited by AM. However, cells differentiated with 1 mmol L(-1) CaCl2 lose their ability to secrete IL-6 but not AM, which could be acting as an antimicrobial peptide.

Tissue factor mediates inflammation

The role of tissue factor (TF) in inflammation is mediated by blood coagulation. TF initiates the extrinsic blood coagulation that proceeds as an extracellular signaling cascade by a series of active serine proteases: FVIIa, FXa, and thrombin (FIIa) for fibrin clot production in the presence of phospholipids and Ca2+. TF upregulation resulting from its enhanced exposure to clotting factor FVII/FVIIa often manifests not only hypercoagulable but also inflammatory state. Coagulant mediators (FVIIa, FXa, and FIIa) are proinflammatory, which are largely transmitted by protease-activated receptors (PAR) to elicit inflammation including the expression of tissue necrosis factor, interleukins, adhesion molecules (MCP-1, ICAM-1, VCAM-1, selectins, etc.), and growth factors (VEGF, PDGF, bFGF, etc.). In addition, fibrin, and its fragments are also able to promote inflammation. In the event of TF hypercoagulability accompanied by the elevations in clotting signals including fibrin overproduction, the inflammatory consequence could be enormous. Antagonism to coagulation-dependent inflammation includes (1) TF downregulation, (2) anti-coagulation, and (3) PAR blockade. TF downregulation and anti-coagulation prevent and limit the proceeding of coagulation cascade in the generation of proinflammatory coagulant signals, while PAR antagonists block the transmission of such signals. These approaches are of significance in interrupting the coagulation-inflammation cycle in contribution to not only anti-inflammation but also anti-thrombosis for cardioprotection.

Adrenomedullin: regulator of systemic and cardiac homeostasis in acute myocardial infarction

During and following acute myocardial infarction, a variety of endogenous mediators are elevated, one of which is adrenomedullin (AM). AM is a multifunctional peptide that has been identified as having a putative beneficial role following an ischemic insult at both systemic and local levels. Classically described as a potent vasodilator, natriuretic, and diuretic agent, experimental infarct models also demonstrate AM to exhibit antiproliferative and antiapoptotic functions in the myocardium, counterregulating the effects of mediators such as angiotensin-II and endothelin-1. Less well documented are the angiogenic and inflammatory modulating potentials of AM, which may also contribute toward reducing adverse ventricular remodeling. The review examines clinical and experimental studies, looking at the effects of AM and cellular mechanisms that could be involved in mediating cardioprotective effects and ultimately optimizing left ventricular remodeling. Finally, the possibility of enhancing endogenous actions of AM by pharmacological intervention is considered.

Adrenomedullin signals through NF-kappaB in epithelial cells

Adrenomedullin is a peptide found in a variety of cells and tissues and involved in a multitude of biological processes. Recently, adrenomedullin has been identified as a host defense peptide and as such it plays a role in the inflammatory response. The transcription factor NF-kappaB is a major regulator of genes involved in the inflammatory response and the aim of this study was to determine whether NF-kappaB played a role in the inflammatory process triggered by adrenomedullin. Skin epithelial cells (HaCaTs) were used as our model in vitro. Western blot analysis from adrenomedullin-stimulated HaCaT cells revealed a rapid degradation of NF-kappaB inhibitor alpha and beta followed by the translocation of free NF-kappaB to the nucleus, where it was detected by Texas Red immunostaining after incubation with adrenomedullin for 15 min. Electromobility shift assay showed that NF-kappaB present in the nucleus was active, since it bound to a probe containing an NF-kappaB binding site. Supershift assays indicated that p50 and p65, members of the NF-kappaB family, were both part of the NF-kappaB dimmers involved in adrenomedullin cell signaling. HaCaTs secreted interleukin-6 in response to AM, which was significantly attenuated by the NF-kappaB inhibitor SN-50. Taken together, the data lend support for an immunoregulatory role for AM.

Presentation of ICAM-1 Protein at the Cell Surface of Oral Keratinocytes in the Presence of Adrenomedullin and Corticotrophin

Increasing evidence suggests that adrenomedullin (AM) and corticotrophin (ACTH) are immunomodulatory. Intercellular adhesion molecule-1 (ICAM-1) plays an important role in the recruitment of leukocytes not only from peripheral blood into inflamed tissues but also into epithelia. We have investigated the effects of AM and ACTH on the expression of ICAM-1 by human oral keratinocytes. The human oral keratinocyte cell line H357 was incubated with either AM or ACTH for up to 8 hrs and ICAM-1 expression was measured by cell surface ELISA. ICAM-1 was up regulated by both peptides and this was attenuated by the adenylyl cyclase inhibitor SQ22,536 and the NF-kappaB inhibitor SN-50. H357 cells constitutively express ICAM-1 mRNA and expression of this gene was significantly modulated by AM and ACTH. Furthermore AM caused translocation of NF-kappaB from the cytoplasm to the nucleus. This is the first report describing up regulation of ICAM-1 in oral keratinocytes by AM and ACTH and the results suggest both cAMP and NF-kappaB may play a role. These results further suggest both peptides may have an immunostimulatory role in oral muocsa and skin.

Adrenomedullin is highly expressed in blood monocytes associated with acute Kawasaki disease: a microarray gene expression study

Kawasaki disease (KD) is an acute inflammatory disorder of children frequently associated with the development of coronary artery abnormalities. Although a great deal is known about inflammatory and immune responses in acute KD, the mechanisms linking the immune response to vascular changes are not known. To gain further insight into this process, we performed a microarray gene expression analysis on RNA isolated from the peripheral blood mononuclear cells of four patients with KD during both their acute and convalescent phases. Forty-seven genes of 7129 genes examined showed an increased expression in three or all four patients in the acute compared with the convalescent phase of KD. Fourteen of these genes were significantly (p < 0.05) up-regulated, including several inflammatory response genes (e.g. S-100 A9 protein) and also anti-inflammatory genes (e.g. TSG-6). Of greatest interest, the adrenomedullin (ADM) gene, known to be associated with coronary artery vasodilation, was up-regulated in the acute phase of KD (p = 0.024). Up-regulation of ADM in the acute phase of KD was confirmed in peripheral blood mononuclear cells of 11 additional KD patients by reverse transcriptase-PCR (p < 0.01). Isolated blood monocytes but not lymphocytes were demonstrated by real-time PCR to have increased ADM mRNA (p = 0.01). Plasma ADM protein level in 32 additional KD patients was also confirmed to be higher in acute KD compared with convalescent KD (p < 0.032). It is interesting that from microarray results, other molecules known to be associated with coronary dilation, including nitric oxide, prostacyclin, acetylcholine, bradykinin, substance P, and serotonin, were not elevated in acute KD. Our current study suggests that ADM-expressing monocytes that infiltrate the coronary vascular wall may be the cause of coronary dilation in the acute phase of KD.