Placenta-derived mesenchymal stem cells attenuate secondary brain injury after controlled cortical impact in rats by inhibiting matrix metalloproteinases

Background:As a form of biological therapy,placenta-derived mesenchymal stem cells(PDMSCs)exhibit considerable promise in addressing the complex pathological processes of traumaticbrain injury(TBI)due to their multi-target and multi-pathway mode of action.Material&Methods:This study investigates the protective mechanisms and benefits of PDMSCs in mitigating the effects of controlled cortical impact(CCI)in rats and glutamate-induced oxidative stress injury in HT22 cells in vitro.Our primary objective is to provide evidence supporting the clinical application of PDMSCs.Results:In the in vivo arm of our investigation,we observed a swift elevation of matrix metalloproteinase-9(MMP-9)in the proximal cortex of injured brain tissues after CCI.PDMSCs,distinguished by their heightened expression of metalloproteinase tissue inhibitors-1 and-2(TIMP-1 and TIMP-2):were intravenously administered via the caudal vein.This intervention yielded significant reductions in the permeability of the blood-brain barrier(BBB):the extent of brain edema,the levels of inflammatory cytokines IL-1βand TNF-αin damaged brain tissue,and the activation status of microglia in CCI-afflicted rats.In the realm of in vitro experiments,PDMSC-conditioned media demonstrated substantial reductions in mortality rates and cleaved caspase-3 levels in glutamate-induced HT22 cells compared with conventional media.Notably,this advantage was negated upon the introduction of neutralizing antibodies targeting TIMP-1 and TIMP-2.Conclusion:Collectively,our findings underscore the potential of PDMSCs in alleviating oxidative stress injury and secondary brain injury in the pathological process of TBI.

Expression of matrix metalloproteinases 2 and 9 in human gastric cancer and superficial gastritis

AIM:To assess expression of matrix metalloproteinases 2(MMP2)and MMP9 in gastric cancer,superficial gastritis and normal mucosa,and to measure metalloproteinase activity.METHODS:MMP2 and MMP9 mRNA expression was determined by quantitative real-time polymerase chain reaction.Normalization was carried out using three different factors.Proteins were analyzed by quantitative gelatin zymography(qGZ).RESULTS:18S ribosomal RNA(18SRNA)was very highly expressed,while hypoxanthine ribosyltransferase-1(HPRT-1)was moderately expressed.MMP2 was highly expressed,while MMP9 was not detected or lowly expressed in normal tissues,moderately or highly expressed in gastritis and highly expressed in cancer.Relative expression of 18SRNA and HPRT-1 showed no significant differences.Significant differences in MMP2 and MMP9 were found between cancer and normal tissue,but not between gastritis and normal tissue.Absolute quantification of MMP9 echoed this pattern,but differential expression of MMP2 proved conflictive.Analysis by qGZ indicated significant differences between cancer and normal tissue in MMP-2,total MMP-9,250 and 110 kDa bands.CONCLUSION:MMP9 expression is enhanced in gastric cancer compared to normal mucosa;interpretation of differential expression of MMP2 is difficult to establish.

Complex role of matrix metalloproteinases in angiogenesis

Matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMP) play a significant role in regulating angiogenesis, the process of new blood vessel formation. Interstitial collagenase (MMP-1), 72 kDa gelatinase A/type IV collagenase (MMP-2), and 92 kDa gelatinase B/type IV collagenase (MMP-9) dissolve extracellular matrix (ECM) and may initiate and Promote angiogenesis. TIMP-1, TIMP-2, TIMP-3, and possibly,TIMP-4 inhibit neovascularisation. A new paradigm is emerging that matrilysin (MMP-7), MMP-9, and metalloelastase (MMP-12) may block angiogehesis by converting plasndnogen to angiostatin, which is one of the most potent angiogenesis antagonists. MMPs and TIMPs play a complex role in regulating angiogenesis. An understanding of the biochemical and cellular pathways and mechanisms of angiogenesis will provide importal information to allow the control of angiogenesis, e.g. the stimulation of angiogenesis for coronary collateral circulation formation; while the inhibition for treating arthritis and cancer.

The Role of Host-derived Dentinal Matrix Metalloproteinases in Reducing Dentin Bonding of Resin Adhesives

Dentin matrix metalloproteinases （MMPs） are a family of host-derived proteolytic enzymes trapped within mineralized dentin matrix, which have the ability to hydrolyze the organic matrix of demineralized dentin. After bonding with resins to dentin there are usually some exposed collagen fibrils at the bottom of the hybrid layer owing to imperfect resin impregnation of the demineralized dentin matrix. Exposed collagen fibrils might be affected by MMPs inducing hydrolytic degradation, which might result in reduced bond strength.Most MMPs are synthesized and released from odontoblasts in the form of proenzymes, requiring activation to degrade extracellular matrix components. Unfortunately, they can be activated by modem self-etch and etch-and-rinse adhe- sives. The aim of this review is to summarize the current knowledge of the role of dentinal host-derived MMPs in dentin matrix degradation. We also discuss various available MMP inhibitors, especially chlorhexidine, and suggest that they could provide a potential pathway for inhibiting collagen degradation in bonding interfaces thereby increasing dentin bonding durability.

Resveratrol inhibits matrix metalloproteinases to attenuate neuronal damage in cerebral ischemia:a molecular docking study exploring possible neuroprotection

The main pathophysiology of cerebral ischemia is the structural alteration in the neurovascular unit, coinciding with neurovascular matrix degradation. Resveratrol has been reported to be one of the most potent chemopreventive agents that can inhibit cellular processes associated with ischemic stroke. Matrix metalloproteinases （MMPs） has been considered as a potential drug target for the treatment of cerebral ischemia. To explore this, we tried to investigate the inter-action of resveratrol with MMPs through molecular docking studies. At 30 minutes before and 2 hours after cerebral ischemia/reperfusion induced by occlusion of the middle cerebral artery, 40 mg/kg resveratrol was intraperitoneally administered. After resveratrol administration, neu-rological function and brain edema were significantly alleviated, cerebral infarct volume was signiifcantly reduced, and nitrite and malondialdehyde levels in the cortical and striatal regions were signiifcantly decreased. The molecular docking study of resveratrol and MMPs revealed that resveratrol occupied the active site of MMP-2 and MMP-9. The binding energy of the complexes was –37.848672 kJ/mol and –36.6345 kJ/mol for MMP-2 and MMP-9, respectively. In case of MMP-2, Leu 164, Ala 165 and Thr 227 were engaged in H-Bonding with resveratrol and in case of MMP-9, H-bonding was found with Glu 402, Ala 417 and Arg 424 residues. These ifndings collectively reveal that resveratrol exhibits neuroprotective effects on cerebral ischemia through inhibiting MMP-2 and MMP-9 activity.

Matrix metalloproteinases and gastrointestinal cancers: Impacts of dietary antioxidants

The process of carcinogenesis is tightly regulated by antioxidant enzymes and matrix degrading enzymes, namely, matrix metalloproteinases(MMPs). Degradation of extracellular matrix(ECM) proteins like collagen, proteoglycan, laminin, elastin and fibronectin is considered to be the prerequisite for tumor invasion and metastasis. MMPs can degrade essentially all of the ECM components and, most MMPs also substantially contribute to angiogenesis, differentiation, proliferation and apoptosis. Hence, MMPs are important regulators of tumor growth both at the primary site and in distant metastases; thus the enzymes are considered as important targets for cancer therapy. The implications of MMPs in cancers are no longer mysterious; however, the mechanism of action is yet to be explained. Herein, our major interest is to clarify how MMPs are tied up with gastrointestinal cancers. Gastrointestinal cancer is a variety of cancer types, including the cancers of gastrointestinal tract and organs, i.e., esophagus, stomach, biliary system, pancreas, small intestine, large intestine, rectum and anus. The activity of MMPs is regulated by its endogenous inhibitor tissue inhibitor of metallopro-teinase(TIMP) which bind MMPs with a 1:1 stoichiometry. In addition, RECK(reversion including cysteinerich protein with kazal motifs) is a membrane bound glycoprotein that inhibits MMP-2,-9 and-14. Moreover, α2-macroglobulin mediates the uptake of several MMPs thereby inhibit their activity. Cancerous conditions increase intrinsic reactive oxygen species(ROS) through mitochondrial dysfunction leading to altered protease/anti-protease balance. ROS, an index of oxidative stress is also involved in tumorigenesis by activation of different MAP kinase pathways including MMP induction. Oxidative stress is involved in cancer by changing the activity and expression of regulatory proteins especially MMPs. Epidemiological studies have shown that high intake of fruits that rich in antioxidants is associated with a lower cancer incidence. Evidence indicates that some antioxidants inhibit the growth of malignant cells by inducing apoptosis and inhibiting the activity of MMPs. This review is discussed in six subchapters, as follows.

Role of matrix metalloproteinases in cholestasis and hepatic ischemia/reperfusion injury:A review

Matrix metalloproteinases(MMPs) are a family ofproteases using zinc-dependent catalysis to break down extracellular matrix(ECM) components, allowing cell movement and tissue reorganization. Like many other proteases, MMPs are produced as zymogens, an inactive form, which are activated after their release from cells. Hepatic ischemia/reperfusion(I/R) is associated with MMP activation and release, with profound effects on tissue integrity: their inappropriate, prolonged or excessive expression has harmful consequences for the liver. Kupffer cells and hepatic stellate cells can secrete MMPs though sinusoidal endothelial cells are a further source of MMPs. After liver transplantation, biliary complications are mainly attributable to cholangiocytes, which, compared with hepatocytes, are particularly susceptible to injury and ultimately a major cause of increased graft dysfunction and patient morbidity. This paper focuses on liver I/R injury and cholestasis and reviews factors and mechanisms involved in MMP activation together with synthetic compounds used in their regulation. In this respect, recent data have demonstrated that the role of MMPs during I/R may go beyond the mere destruction of the ECM and may be much more complex than previously thought. We thus discuss the role of MMPs as an important factor in cholestasis associated with I/R injury.

Expressions of matrix metalloproteinases 1 and 3 and their tissue inhibitors in the conjunctival tissue and fibroblasts cultured from conjunctivochalasis

AIM：To investigate the expression of matrix metalloproteinases 1 and 3（MMP-1 and MMP-3） and their tissue inhibitors of metalloproteinases 1 and 3（ TIMP-1 and TIMP-3） in the conjunctiva of eyes with conjunctivochalasis（CCh）.METHODS：The conjunctival tissue was obtained from the CCh patients and controls,the MMPs/TIMPs expression concentration was determined by enzyme-linked immunosorbent assay（ELISA） and immunofluorescence staining.The expression levels of MMPs/TIMPs in the CCh fibroblasts were determined by analyzing its concentration in the cellular supernatant that was abstracted from the in vitro cultured CCh fibroblasts.RESULTS：MMP-1 and MMP-3 levels determined by ELISA were both significantly higher in the CCh group than that in the control group（P= 0.042,0.022,respectively）,so was the levels of TIMP-1（P= 0.010）.No significant difference in the expression of TIMP-3 in conjunctiva was found between the two groups（P= 0.298）.The expression of MMP-1 and MMP-3 were both up-regulated significantly in the CCh group（P= 0.040,0.001,respectively） on immunofluorescence staining.MMP-1 and MMP-3 expression in the fibroblasts were both significantly higher in the CCh group than that in the control group（P= 0.027,0.001,respectively）,while neither the TIMP-1 nor TIMP-3 expression was significantly different between the two groups（P= 0.421,0.237,respectively）.CONCLUSION：The overexpression of MMP-1 and MMP-3 in conjunctival tissue and fibroblasts may play an important role in the pathogenesis and development of CCh.

Single-nucleotide polymorphisms of matrix metalloproteinases and their inhibitors in gastrointestinal cancer

Matrix metalloproteinases(MMPs) are implicated in cancer development and progression and are associated with prognosis.Single-nucleotide polymorphisms(SNPs) of MMPs,most frequently located in the promoter region of the genes,have been shown to influence cancer susceptibility and/or progression.SNPs of MMP-1,-2,-3,-7,-8,-9,-12,-13 and-21 and of the tissue inhibitor of metalloproteinases(TIMPs) TIMP-1 and TIMP-2 have been studied in digestive tract tumors.The contribution of these polymorphisms to the cancer risk and prognosis of gastrointestinal tumors are reviewed in this paper.

EXPRESSION OF mRNA FOR MEMBRANE-TYPE 1, 2, AND 3 MATRIX METALLOPROTEINASES IN HUMAN LARYNGEAL CANCER

To investigate correlation of expressions of membrane-type 1, 2, and 3 matrix metalloproteinases (MT1, MT2, and MT3-MMP) to the invasion and metastases in laryngeal cancer. Methods Reverse transcription-polymerase chain reaction (RT-PCR) was used to examine the mRNA level of MT1, MT2, and MT3-MMP in 24 patients with laryngeal cancer. The relationships of these three MT-MMP expressions to clinico-pathology were analyzed by statistics. Results The expressions of MT1, MT2, and MT3-MMP were significantly higher in laryngeal cancer tissues than those in para-tumorous tissues (P < 0.01) and had a close relationship with invasive depth (P < 0.05). But no significantly different expressions of these three MT-MMPs were found in different primary location and different histological grade of laryngeal cancer (P > 0.05). The expression of MT1-MMP was obviously higher in patients with metastatic lymph nodes than that in patients without metastatic lymph nodes (P < 0.05). Conclusion MT1, MT2, and MT3-MMP play an important role in the progression of laryngeal cancer, and MT1-MMP may serve as a reliable marker in estimating invasive and metastatic potency of laryngeal cancer. Suppressing expressions of MT1, MT2, and MT3-MMP early may inhibit the invasion and metastases of laryngeal cancer.

Inhibition of matrix metalloproteinases expression in human dental pulp cells by all-trans retinoic acid

All-trans retinoic acid（ATRA） inhibits matrix metalloproteinase（MMP）-2 and MMP-9 in synovial fibroblasts, skin fibroblasts,bronchoalveolar lavage cells and cancer cells, but activates MMP-9 in neuroblast and leukemia cells. Very little is known regarding whether ATRA can activate or inhibit MMPs in human dental pulp cells（HDPCs）. The purpose of this study was to determine the effects of ATRA on the production and secretion of MMP-2 and-9 in HDPCs. The productions and messenger RNA（mRNA） expressions of MMP-2 and-9 were accessed by gelatin zymography and real-time polymerase chain reaction（PCR）, respectively. ATRA was found to decrease MMP-2 level in a dose-dependent manner. Significant reduction in MMP-2 mRNA expression was also observed in HDPCs treated with 25 mmol？L21ATRA. However, HDPCs treated with ATRA had no effect on the pattern of MMP-9 produced or secreted in either cell extracts or conditioned medium fractions. Taken together, ATRA had an inhibitory effect on MMP-2 expression in HDPCs,which suggests that ATRA could be a candidate as a medicament which could control the inflammation of pulp tissue in vital pulp therapy and regenerative endodontics.

Matrix metalloproteinases contribute to kidney fibrosis in chronic kidney diseases

Matrix metalloproteinases(MMPs) are members of the neutral proteinase family. They were previously thought to be anti-fibrotic because of their ability to degrade and remodel of extracellular matrix. However, recent studies have shown that MMPs are implicated in initiation and progression of kidney fibrosis through tubular cell epithelial–mesenchymal transition(EMT) as well as activation of resident fibroblasts, endothelial-mesenchymal transition(Endo MT) and pericyte-myofibroblast transdifferentiation. Interstitial macrophage infiltration has also been shown to correlate with the severity of kidney fibrosis in various chronic kidney diseases. MMPs secreted by macrophages, especially MMP-9, hasbeen shown by us to be profibrotic by induction of tubular cells EMT. EMT is mainly induced by transforming growth factor-β(TGF-β). However, MMP-9 was found by us and others to be up-regulated by TGF-β1 in kidney tubular epithelial cells and secreted by activated macrophages, resulting in EMT and ultimately kidney fibrosis. Therefore, MMP-9 may serve as a potential therapeutic target to prevent kidney fibrosis in chronic kidney disease. This review, by a particular focus on EMT, seeks to provide a comprehensive understanding of MMPs, especially MMP-9, in kidney fibrosis.

Metalloproteinases as mediators of inflammation and the eyes： molecular genetic underpinnings governing ocular pathophysiology

There are many vision threatening diseases of the eye affecting millions of people worldwide. In this article, we are summarizing potential role of various matrix metalloproteinases （MMPs）; the Zn （2＋）-dependent endoproteases in eye health along with pathogenesis of prominent ocular diseases such as macular degeneration, diabetic retinopathy, and glaucoma via understanding MMPs regulation in affected patients, interactions of MMPs with their substrate molecules, and key regulatory functions of tissue inhibitor of metalloproteinases （TIMPs） towards maintaining overall homeostasis.

Matrix metalloproteinases and their expression in mammary gland

The matrix metalloproteinases (MMPs) are a family of zinc-dependent endopeptidases that play a key role in both normal and pathological processes involving tissue remodeling events. The expression of these proteolytic enzymes is highly regulated by a balance between extracellular matrix (ECM) deposition and its degradation, and is controlled by growth factors, cytokines, hormones, as well as interactions with the ECM macromolecules. Furthermore, the activity of the MMPs is regulated by their natural endogenous inhibitors, which are members of the tissue inhibitor of metalloproteinases (TIMP) family. In the normal mammary gland, MMPs are expressed during ductal development, lobulo-alveolar development in pregnancy and involution after lactation. Under pathological conditions, such as tumorigenesis, the dysregulated expression of MMPs play a role in tumor initiation, progression and malignant conversion as well as facilitating invasion and motastasis of malignant cells through degradation of the ECM and basement membranes. Matrix metalloproteinases and their expression in mammary gland

Production and activity of matrix metalloproteinases during liver fibrosis progression of chronic hepatitis C patients

BACKGROUND Matrix metalloproteinases(MMPs)participate in the degradation of extracellular matrix compounds,maintaining the homeostasis between fibrogenesis and fibrolytic processes in the liver.However,there are few studies on the regulation of liver MMPs in fibrosis progression in humans.AIM To assess the production activity and regulation of matrix metalloproteinases in liver fibrosis stages in chronic hepatitis C(CHC).METHODS A prospective,cross-sectional,multicenter study was conducted.CHC patients were categorized in fibrosis grades through FibroTest®and/or FibroScan®.Serum MMP-2,-7,and-9 were determined by western blot and multiplex suspension array assays.Differences were validated by the Kruskal-Wallis and Mann-Whitney U tests.The Spearman correlation coefficient and area under the receiver operating characteristic curve were calculated.Collagenolytic and gelatinase activity was determined through the Azocoll substrate and zymogram test,whereas tissue inhibitor of metalloproteinase-1 production was determined by dot blot assays.RESULTS Serum concentrations of the MMPs evaluated were higher in CHC patients than in healthy subjects.MMP-7 distinguished early and advanced stages,with a correlation of 0.32(P<0.001),and the area under the receiver operating characteristic displayed moderate sensitivity and specificity for MMP-7 in F4(area under the receiver operating characteristic,0.705;95%confidence interval:0.605-0.805;P<0.001).Collagenolytic activity was detected at F0 and F1,whereas gelatinase activity was not detected at any fibrosis stage.Tissue inhibitor of metalloproteinase-1 determination showed upregulation in F0 and F1 but downregulation in F2(P<0.001).CONCLUSION High concentrations of inactive MMPs were present in the serum of CHC patients,reflecting the impossibility to restrain liver fibrosis progression.MMPs could be good diagnostic candidates and therapeutic targets for improving novel strategies to reverse liver fibrosis in CHC.

Effect of heparin on high glucose induced proliferation and expression of matrix metalloproteinases in normal human mesangial cells

Background The pathogenesis of diabetic nephropathy (DN) is a complex pathophysiological process.Its precise mechanism is not fully known. In recent years it has been recognized that synthesis of various extracelluar matrix (ECM) components may increase, and that degradation of ECM may decrease in DN. It was reported heparin could inhibit mesangial cells proliferation in vitro. The main aim of this study is to explore whether heparin inhibits proliferation of mesangial cells grown in high glucose concentration and to measure the effect of heparin on matrix metalloproteinases (MMPs) expression in mesangial cells. Methods The medium contained either low glucose (5 mmol/L) or high glucose (25 mmol/L). The concentrations of heparin in the culture medium were 0, 25, 50,100, 200 or 400 μg/mL. A metabolic (WST-1) assay was used to measure mesangial cell proliferation and Western blot analysis was used to measure MMPs expression of mesangial cells. Results Normal human mesangial cell (NHMC) proliferation was higher in high glucose (HG) medium than in low glucose (LG) medium. They showed a 1.93 fold expansion after 72 h in high glucose in contrast to a 1.63 fold expansion in low glucose. In the presence of heparin, mesangial cells proliferation was inhibited, which was more obvious at high glucose concentrations than at low glucose concentrations. In high glucose, with heparin concentration of 50, 100, 200 and 400 μg/mL, the mesangial cells showed a 0. 61 fold, 0.52 fold, 0.52 fold and 0.41 fold reductions in cell number compared to cells grown without heparin. In low glucose, only concentrations of 200 μg/mL and 400 μg/mL showed reduction in cell number, namely 0.54 fold and 0.45 fold, when compared to cells grown without heparin. In Western blot analysis,MMP1, MMP2, MMP3 and MMP9 was expressed by mesangial cells expressed in both high and low glucose concentrations, which was more prominent in high glucose medium. Incubation of heparin further increased expression of MMP1, MMP2, MMP3 and MMP9. Conclusions This study suggests that glucose can accelerate mesangial cell proliferation while heparin can reduce proliferation, being more obvious at high glucose concentrations. Higher glucose concentrations led to increased MMP expression, which may take part in the regulation of mesangial matrix synthesis and degradation. Addition of heparin resulted in a corresponding increase in MMP expression, most notably at high glucose concentrations, indicating a potentially renoprotective role in DN.

Local inhibition of matrix metalloproteinases reduced M2 macrophage activity and impeded recovery in spinal cord transected rats after treatment with fibroblast growth factor-1 and nerve grafts

Alternatively activated macrophages （M2 macrophages） promote central nervous system regeneration. Our previous study demonstrated that treatment with peripheral nerve grafts and fibroblast growth factor-1 recruited more M2 macrophages and improved partial functional recovery in spinal cord transected rats. The migration of macrophages is matrix metalloproteinase （MMP） dependent. We used a general inhibitor of MMPs to influence macrophage migration, and we examined the migration of macrophage populations and changes in spinal function. Rat spinal cords were completely transected at Ts, and 5 mm of spinal cord was removed （group T）. In group R, spinal cord-transected rats received treatment with fibroblast grow th factor- 1 and peripheral nerve grafts. In group RG, rats received the same treatment as group R with the addition of 200 μM GM6001 （an MMP inhibitor） to the fibrin mix. We found that MMP-9, but not MMP- 2, was upregulated in the graft area of rats in group R. Local application of the MMP inhibitor resulted in a reduction in the ratio of arginase-1 （M2 macrophage subset）/inducible nitric oxide synthase-postive cells. When the MMP inhibitor was applied at 8 weeks postoperation, the partial functional recovery observed in group R was lost. This effect was accompanied by a decrease in brain-derived neurotrophic factor levels in the nerve graft. These results suggested that the arginase-1 positive population in spinal cord transected rats is a migratory cell population rather than the phenotypic conversion of early iNOS^＋ cells and that the migration of the arginase-1^＋ population could be regulated locally. Simultaneous application of MMP in- hibitors or promotion of MMP activity for spinal cord injury needs to be considered if the coadministered treatment involves M2 recruitment.

Time dependent integration of matrix metalloproteinases and their targeted substrates directs axonal sprouting and synaptogenesis following central nervous system injury

Over the past two decades, many investigators have reported how extracellular matrix molecules act to regulate neuroplasticity. The majority of these studies involve proteins which are targets of matrix metalloproteinases. Importantly, these enzyme/substrate interactions can regulate degenerative and regenerative phases of synaptic plasticity, directing axonal and dendritic reorganization after brain insult. The present review first summarizes literature support for the prominent role of matrix metalloproteinases during neuroregeneration, followed by a discussion of data contrasting adaptive and maladaptive neuroplasticity that reveals time-dependent metalloproteinase/substrate regulation of postinjury synaptic recovery. The potential for these enzymes to serve as therapeutic targets for enhanced neuroplasticity after brain injury is illustrated with experiments demonstrating that metalloproteinase inhibitors can alter adaptive and maladaptive outcome. Finally, the complexity of metalloproteinase role in reactive synaptogenesis is revealed in new studies showing how these enzymes interact with immune molecules to mediate cellular response in the local regenerative environment, and are regulated by novel binding partners in the brain extracellular matrix. Together, these different examples show the complexity with which metalloproteinases are integrated into the process of neuroregeneration, and point to a promising new angle for future studies exploring how to facilitate brain plasticity.

Structure, expression, and developmental function of early divergent forms of metalloproteinases in Hydra

Metalloproteinases have a critical role in a broad spectrum of cellular processes ranging from the break-down of extracellulax matrix to the processing of signal transduction-related proteins. These hydrolyticfunctions underlie a variety of mechanisms related to developmental processes as well as disease states.Structural analysis of metalloproteinases from both invertebrate and vertebrate species indicates that theseenzymes are highly conserved and arose early during metazoan evolution. In this regard, studies from vari-ous laboratories have reported that a number of classes of metalloproteinases are found in hydra, a memberof Cnidaria, the second oldest of existing animal phyla. These studies demonstrate that the hydra genomecontains at least three classes of metalloproteinases to include members of the 1) astacin class, 2) matrix met-alloproteinase class, and 3) neprilysin class. Functional studies indicate that these metalloproteinases playdiverse and important roles in hydra morphogenesis and cell differentiation as well as specialized functionsin adult polyps. This article will review the structure, expression, and function of these metalloproteinasesin hydra.

Expression of matrix metalloproteinases and tissue inhibitor metalloproteinases increases in X-irradiated rat ileum despite the disappearance of CD8a T cells

AIM： To investigate their expression and activity in the rat ileum after exposure to ionizing radiation along with that of the cellular effectors and molecular mediators involved in the regulation of MMPs. METHODS： Rats were exposed to a single 10-Gy dose of X-rays delivered to the abdomen. A combination of methods, such as zymography, immunohistochemistry and real time reverse transcriptase-polymerase chain reaction, were used to localize and quantify MMPs and the molecules involved in MMP activating and inhibitory pathways （plasmin/ plasminogen, TIMPs）, CD^8＋, as well as inflammatory （interleukin （IL）-1β, IL-8, tumor necrosis factor-s, TNF-α） and fibrogenic mediators （transforming growth factor- β1-3） within ileal tissue at 1, 3, and 7 d after irradiation. RESULTS： A marked increase in MMP-2 and -14 mRNA and protein levels associated with an increased activity of MMP-2 was observed in irradiated ileal tissue. MMP-2 and -14 expression was mainly observed in inflammatory, epithelial, and mesenchymal cells, whereas a slight increase in MMP-3 expression was detected in the few infiltrating macrophages at d i after irradiation. Conversely, MMP-1, -7, and -9 mRNA levels were not found to be affected by abdominal irradiation. Irradiation was found to induce disappearance of CD^8＋ cells. Furthermore, we have observed that TNF-α and IL-1β protein levels increased 6 h after irradiation, whereas those of IL-8 only increased after 3 d and was concomitant with neutrophil infiltration. In addition, the expressions of molecules involved in MMP activating and inhibitory pathways （urokinase-type plasminogen activator andtissue-type plasminogen activator; TIMP-1, TIMP-2, and plasminogen activator-inhibitor-i） were found to be increased after abdominal irradiation. CONCLUSION： This study showed that abdominal irradiation induces an acute remodeling of the ileum associated with an increased expression of MMPs and TIMPs that do not involve CD^8＋ T cells but involve mesenchymal and epithelial cells, although to a lesser extent, and probably even soluble inflammatory and fibrogenic mediators.