Buket Reel

Diverse patterns of cyclooxygenase-independent metalloproteinase gene regulation in human monocytes.

BACKGROUND AND PURPOSE Matrix metalloproteinase (MMP) production from monocyte/macrophages is implicated in matrix remodelling and modulation of inflammation. However, knowledge of the patterns and mechanisms of gene regulation of MMPs and their endogenous tissue inhibitors (TIMPs) is fragmentary. MMP up‐regulation may be a target for cyclooxygenase (COX) and prostaglandin (PG) receptor inhibition, but the extent and mechanisms of COX‐independent MMP up‐regulation are unclear.

MMP-2 and MMP-9 Alteration in Response to Collaring in Rabbits: The Effects of Endothelin Receptor Antagonism

Matrix metalloproteinases (MMPs), and, in particular, gelatinases (MMP-2 and MMP-9), have been implicated in vascular cell proliferation and/or migration, contributing to intimal thickening, an essential stage in the development of atherosclerosis and restenosis following balloon angioplasty. Endothelin, a strong chemoatractant and mitogen, has been shown to promote smooth muscle cell proliferation and migration by activating MMPs via endothelin-A (ETA) receptors. The positioning of a soft silicon collar around the left carotid artery in rabbits results in intimal thickening. In this study, we investigate the possible role of gelatinases and the effect of a nonselective ETA/ETB receptor antagonist, TAK-044 (5 mg/kg body weight/day, subcutaneously [sc]), on these enzymes. Our results demonstrated that both MMP-2 and MMP-9 activities increased in response to collaring in placebo group, while treatment with TAK-044 significantly suppressed both gelatinase activities and proMMP-2 levels, and inhibited intimal thickening in collared arteries. These results suggest that either enhanced MMP expression or endothelin receptor antagonism may be involved in the formation of intimal thickening in this model.

Taurine inhibits increased MMP-2 expression in a model of oxidative stress induced by glutathione depletion in rabbit heart.

Matrix metalloproteinase enzymes (MMPs) activated by oxidative stress are involved in the pathogenesis of cardiovascular diseases. Glutathione (GSH) plays an important protective role against oxidatively induced damage in mammalian tissues. We investigated the possible role of gelatinases and the effect of the semiessential amino acid 2-aminoethanesulfonic acid (taurine) in oxidatively induced damage by GSH depletion in rabbit cardiac tissues. Rabbits were treated with buthionine sulfoximine (BSO), an effective GSH-depleting compound. BSO treatment significantly reduced GSH and increased MDA (malondialdehyde) levels. BSO treatment caused significant increase in proMMP-2 levels. MMP-9 (pro and active) expressions were not found in either treated- or untreated heart tissues. TIMP-1(endogenous inhibitor of MMP-9) and MT-MMP1 (endogenous activator of MMP-2) were not affected by BSO. Immunoscoring showed that MMP-2 expression significantly increased in hearts from BSO treated group but MMP-9 antibody did not show any significant positive immunostaining from all groups. Type I procollagen and total collagen did not significantly alter in heart tissues from all treatment groups. Taurine restored the increased MDA and the diminished GSH levels by BSO treatment. Pro MMP-2 expression was prevented by taurine. These results suggest that MMP-2 is a major gelanitase in rabbit hearts under oxidative stress and pharmacological inhibition of MMP-2 activation by taurine could represent a useful strategy for the prevention and/or treatment of different cardiovascular disorders.

The effects of zoledronic acid on neointimal hyperplasia: a rabbit carotid anastomosis model.

OBJECTIVE The aim of the present study was to investigate the effect of zoledronic acid (ZA), as a matrix metalloproteinase inhibitor, on neointimal hyperplasia in rabbit carotid anastomosis model. METHODS New Zealand male rabbits were divided into two groups as placebo and treatment groups in this experimental study. After anesthesia, the right carotid artery of each rabbit was end-to-end anastomosed with an 8/0 polypropylene suture. Left carotid artery was kept as control without any operation. Placebo group (n=6) received phosphate buffered saline (PBS) (0.5mL/kg/day/s.c.) for 28 days postoperatively, whereas ZA group (n=6) received ZA (100 µg/kg/day/s.c.) for the same period. After sacrification, the anastomosed and control arteries were isolated. Morphometric and immunohistochemical examinations were performed. Statistical analyses of morphometric and immunohistochemical data were performed using two-way ANOVA and Chi-square test respectively. RESULTS In PBS group, vascular injury in the anastomosed artery significantly increased the intimal area (anastomosed: 112.51±61.18 µm(2)*1000 vs. control: 22.62±4.26 µm(2)*1000, p<0.01) and intima/media index (anastomosed: 0.347±0.29 vs. control: 0.075±0.01, p<0.05) compared to control artery. ZA significantly reduced the intimal area (39.29±18.21 µm(2)*1000 , p<0.01) and intima/media index (0.112±0.07, p<0.05) compared to PBS group. Additionally, α-smooth muscle actin immunopositivity was found significantly decreased in anastomosed arteries from ZA group (ZA: 2.33±0.52 vs. PBS: 3.50±0.5, p<0.05). Moreover, intensive gelatinase (MMP-2 and MMP-9) immunoreactivities were clearly seen in anastomosed arteries compared to control arteries from PBS group. ZA apparently decreased immunopositivities for gelatinases in anastomosed arteries. CONCLUSION ZA might be a promising agent for prevention of neointimal hyperplasia, which is the most significant cause of graft failures in late postoperative period.

The role of endothelin receptor antagonism in collar‐induced intimal thickening and vascular reactivity changes in rabbits

Intimal thickening, due to smooth muscle cell migration and proliferation, is considered to be one of the major components of vascular proliferative disorders such as atherosclerosis and restenosis. One experimental model, resulting in intimal thickening in the rabbit, involves placing a silicon collar around the carotid artery, and is used in this study. Endothelin is known to act as a strong mitogen and to stimulate smooth muscle cell proliferation and migration. We investigated the contribution of endothelin to the development of collar‐induced intimal thickening and the effects of TAK‐044, (5mg kg−1 daily, s.c.), a non‐selective ETA/ETB receptor antagonist, on intimal thickening and vascular reactivity changes in the collared rabbit carotid artery. Endothelin levels and the intimal cross‐sectional area, as well as the ratio of intimal area to media (index), increased significantly in collared arteries as compared with those in sham‐operated arteries. TAK‐044 significantly inhibited intimal thickening and also decreased the index without affecting increased endothelin levels in collared arteries. Vascular reactivity changes in response to collaring produced predictable effects, such as decreased contractile responses to vasoconstrictor agents and increased sensitivity to serotonin (5‐hydroxytrypt‐amine, 5‐HT). In terms of contractile responses in this model, TAK‐044, in particular, did not affect collar‐induced vascular reactivity changes. These results suggest that endothelin may be involved in the pathogenesis of collar‐induced intimal thickening. As an endothelin receptor antagonist, TAK‐044 may potentially be beneficial in the treatment of atherosclerosis.

Zoledronate upregulates MMP-9 and -13 in rat vascular smooth muscle cells by inducing oxidative stress

Background Bisphosphonates, including zoledronate, target osteoclasts and are widely used in the treatment of osteoporosis and other bone resorption diseases, despite side effects that include damaging the stomach epithelium. Beneficial and adverse effects on other organ systems, including the cardiovascular system, have also been described and could impact on the use of bisphosphonates as therapeutic agents. Vascular smooth muscle cells (VSMCs) are major constituents of the normal vascular wall and have a key role in intimal thickening and atherosclerosis, in part by secreting MMPs that remodel the extracellular matrix and cleave cell surface proteins or secreted mediators. In this study, we investigated the effects of zoledronate on MMP expression. Methods Rat VSMCs were stimulated by PDGF (50 ng/mL) plus TNF-α (10 ng/mL) or left unstimulated for a further 24 hours in serum-free medium. In other series of experiments, cells were pre-treated either with SC-514 (50 μM) or with apocynin (20 nM) for 2 hours, then zoledronate (100 μM) was added into 2% fetal calf serum containing medium for 24 hours. Results and discussion Using isolated rat VSMCs in culture, zoledronate (100 μM) increased MMP-9 and -13 mRNA expressions but inhibited MMP-2 expression. MMP-9 and MMP-13 up-regulation was shown to depend on the NF-κB pathway; and this was activated by zoledronate. Furthermore, zoledronate elevated the levels of reactive oxygen species detected by either dichlorofluorescein in isolated VSMCs or lucigenin enhanced chemiluminescence in rat aortic rings in vitro. Apocynin, an inhibitor of NADPH oxidase, reversed NF-κB activation and MMP-9 and MMP-13 up-regulation by zoledronate. Conclusion We conclude that zoledronate increases MMP-9 and MMP-13 expressions in rat VSMCs dependent upon stimulation of the NF-κB pathway by reactive oxygen species. Effects on MMP expression may contribute to the pharmacologic profile of bisphosphonates.

The effects of PPARγ agonist rosiglitazone on neointimal hyperplasia in rabbit carotid anastomosis model

BackgroundNeointimal hyperplasia involving smooth muscle cell (SMC) proliferation, migration and extracellular matrix (ECM) degradation is an important component of atherosclerosis. It develops as a response to vascular injury after balloon angioplasty and vascular graft placement. Matrix metalloproteinases (MMPs) induce SMC proliferation, migration and contribute to intimal hyperplasia by degrading ECM. PPARγ agonists inhibit SMC proliferation, migration and lesion formation. In this study, we aimed to investigate the effects of PPARγ agonist rosiglitazone on neointimal hyperplasia and gelatinase (MMP-2 and MMP-9) expressions in rabbit carotid anastomosis model.MethodsNew Zealand white rabbits (n = 13, 2.7–3.2 kg) were divided into placebo and treatment groups. Right carotid artery (CA) was transected and both ends were anastomosed. Treatment group (n = 6) received rosiglitazone (3 mg/kg/day/p.o.) and placebo group (n = 7) received PBS (phosphate buffered saline, 2.5 ml/kg/day/p.o.) for 4 weeks postoperatively. After the sacrification, right and left CAs were isolated. Morphometric analyses and immunohistochemical examinations for gelatinases were performed.ResultsIntimal area (0.055 ± 0.005 control vs 0.291 ± 0.020 μm2 anastomosed, p < 0,05) and index (0.117 ± 0.002 control vs 0.574 ± 0.013 anastomosed, p < 0,01) significantly increased in anastomosed arteries compared to control arteries from placebo group. However, in rosiglitazone-treated group, intimal area (0.291 ± 0.020 PBS vs 0.143 ± 0.027 rosiglitazone, p < 0,05) and index (0.574 ± 0.013 PBS vs 0.263 ± 0.0078 rosiglitazone, p < 0,01) significantly decreased. Furthermore, gelatinase immunopositivity was found to have significantly increased in anastomosed arteries from placebo group and decreased with rosiglitazone treatment.ConclusionsThese results suggest that rosiglitazone may prevent neointimal hyperplasia, which is the most important factor involved in late graft failure, by inhibiting gelatinase enzyme expression.

Effects of treatment with FK409, a nitric oxide donor, on collar-induced intimal thickening and vascular reactivity.

Intimal thickening in arteries is considered a site of predilection for atherosclerosis. In a rabbit model of early atherosclerosis, a silastic collar was placed around the carotid artery, which resulted in the formation of intimal thickening. We investigated whether the oral application of FK409 ((+/-)-(E)-4-ethyl-2-[(E)-hydroxyimino]-5-nitro-3-hexenamide , 10 mg kg(-1) day(-1), p.o.), a nitric oxide donor, inhibited the collar-induced intimal thickening as well as accompanying reactivity changes in rabbit carotid artery. The intimal thickening was significantly inhibited by FK409. The collar treatment increased the pD2 value of 5-hydroxytryptamine (5-HT) whereas it decreased those of phenylephrine and acetylcholine and did not significantly alter that of nitroglycerine. Maximal contractile force development in response to potassium chloride (KCl), 5-HT and phenylephrine was decreased in collared arteries. The collar did not alter the maximal relaxant effects of acetylcholine and nitroglycerine. Despite the significant reduction of intimal thickening, FK409 treatment did not affect these collar-induced modifications in vascular reactivity.

The Effects of Calcium Channel Blockers are not Related to their Chemical Structure in the Collar Model of the Rabbit

Placing a silicone collar around the rabbit carotid artery induces intimal thickening, an early stage in atherosclerosis and restenosis. We investigated whether treatment with oral pranidipine, a new potent, long-lasting dihydropyridine calcium channel blocker (CCB), inhibited collar-induced intimal thickening in addition to the changes in vascular reactivity usually observed in this model. Pranidipine treatment did not inhibit collar-induced intimal thickening. Placing the collar around the carotid artery resulted in the characteristic changes in vascular reactivity, such as increased sensitivity to 5-hydroxytryptamine. Treatment with Nω-nitro-l-arginine (100 μM) and pranidipine, however, did not affect collar-induced changes in vascular reactivity. From results of this and previous studies, we conclude that pranidipine does not prevent collar-induced intimal thickening or collar-induced changes in vascular reactivity. Not all CCBs prevent collar-induced intimal thickening, suggesting that the effects of these agents are not related to their chemical structure and/or their calcium channel-blocking actions.

The Regulation of Matrix Metalloproteinase Expression and the Role of Discoidin Domain Receptor 1/2 Signalling in Zoledronate-treated PC3 Cells.

Discoidin Domain Receptors (DDR1/DDR2) are tyrosine kinase receptors which are activated by collagen. DDR signalling regulates cell migration, proliferation, apoptosis and matrix metalloproteinase (MMP) production. MMPs degrade extracellular matrix (ECM) and play essential role in tumor growth, invasion and metastasis. Nitrogen-containing bisphosphonates (N-BPs) which strongly inhibit osteoclastic activity are commonly used for osteoporosis treatment. They also have MMP inhibitory effect. In this study, we aimed to investigate the effects of zoledronate in PC3 cells and the possible role of DDR signalling and downstream pathways in these inhibitory effects. We studied messenger RNA (mRNA) and protein expressions of MMP-2,-9,-8, DDR1/DDR2 type I procollagen (TIP) and mRNA levels of PCA-1, MMP-13 and DDR-initiated signalling pathway players including K-Ras oncogene, ERK1, JNK1, p38, AKT-1 and BCLX in PC3 cells in the presence or absence of zoledronate (10-100 μM) for 2-3 days. Zoledronate (100 μM) down-regulated DDR1/ DDR2, TIP mRNAs but did not change MMP-13 (collagenase-3) mRNA. However, zoledronate up-regulated MMP-8 (collagenase-2) mRNA. Zoledronate also inhibited mRNA expressions of K-Ras, ERK1, AKT-1, BCLX and PCA-1; but did not change JNK1, p38 mRNA levels. Zoledronate (100 μM) supressed DDR1/DDR2, TIP expressions; and gelatinase (MMP-2/MMP-9) expressions/activities. Conversely, zoledronate up-regulated MMP-8 expression in PC3 cells. Zoledronate down-regulates MMP-2/-9 expressions in PC3 prostate cancer cells. DDR1/DDR2 signalling and DDR-initiated downstream Ras/Raf/ERK and PI3K/AKT pathways may at least partially responsible for MMP inhibitory effect of zoledronate.