The induction of 72-kD gelatinase in T cells upon adhesion to endothelial cells is VCAM-1 dependent

Biomarkers of Endothelial Dysfunction in Women With Polycystic Ovary Syndrome

Polycystic ovary syndrome (PCOS) is the most common endocrine disorder in women of childbearing age. The criteria required for the diagnosis identify various phenotypes, with different reproductive, metabolic, and cardiovascular (CV) risk characteristics. Emerging evidence links adipocyte-secreted hormones as candidates in the pathogenesis of endothelial dysfunction in PCOS, independently of additional risk factors. The aim of this review was to collect, analyze, and qualitatively resynthesize evidence on biomarkers of endothelial dysfunction (visfatin, vascular endothelial growth factor [VEGF], matrix metalloproteinase 9 [MMP-9]) in women with PCOS. Women with PCOS exhibit (a) increased plasma visfatin concentrations compared with controls with a similar body mass index; (b) increased VEGF production along with chronic, mild inflammation; and (c) increased MMP-9 concentrations, which might be related to either excessive CV risk or abnormalities of ovarian extracellular matrix remodeling, multiple cyst formation, follicular atresia, and chronic anovulation. As PCOS has been associated with CV risk, early identification of endothelial dysfunction is clinically relevant.

MMP-2, MMP-9, and TIMP-4 and Response to Aspirin in Diabetic and Nondiabetic Patients with Stable Coronary Artery Disease: A Pilot Study

Background

High on-aspirin treatment platelets reactivity (HPR) is a significant problem in long-term secondary prevention of cardiovascular events. We hypothesize that imbalance between platelets MMPs/TIMPs results in cardiovascular disorders. We also explored whether chronically elevated blood glucose affects MMP-2/TIMP-4 release from platelets.

Materials and Methods

Seventy patients with stable coronary artery disease, supplemented with aspirin, participated in this pilot study. The presence of HPR and/or diabetes mellitus was considered as the differentiating factor. Light aggregometry, impedance aggregometry, and ELISA tests for TXB2, MMP-2, MMP-9, and TIMP-4 were performed in serum, plasma, platelet-rich plasma, and platelets-poor plasma, as appropriate.

Results

Aspirin-HPR did not affect plasma MMP-2, MMP-9, and TIMP-4. Arachidonic acid-induced aggregation of platelets from aspirin-HPR patients did not lead to increased release of MMP-2, MMP-9, and TIMP-4. Studying patients at the lowest TXB2 serum concentration quartile revealed that high concentration of plasma TIMP-4 and TIMP-4 negatively correlated with TXB2 and platelet aggregation. Diabetics showed an increased plasma MMP-2 as well as an increased MMP-2 in supernatants after platelet aggregation. However, diabetes mellitus did not affect MMP-9 and TIMP-4.

Conclusion

Aspirin-HPR did not affect the translocation and release of MMPs and TIMP-4 from platelets. TIMP-4 may serve as a marker of TXA2-mediated platelet aggregation. Chronically elevated plasma glucose increases plasma MMP-2, and HPR potentiates this phenomenon.

-NOD Mice Having a Lyn Tyrosine Kinase Mutation Exhibit Abnormal Neutrophil Chemotaxis

Neutrophils from NOD (Non-Obese Diabetic) mice exhibited reduced migration speed, decreased frequency of directional changes, and loss of directionality during chemotaxis (compared to wild-type [WT] C57BL/6 mice). Additionally, F-actin of chemotaxing NOD neutrophils failed to orient toward the chemoattractant gradient and NOD neutrophil adhesion was impaired. A point mutation near the autophosphorylation site of Lyn in NOD mice was identified. Point mutations of G to A (G1412 in LynA and G1199 in LynB) cause a change of amino acid E393 (glutamic acid) to K (lysine) in LynA (E₃₉₃ →K) (E₃₇₂ of LynB), affecting fMLP-induced tyrosine phosphorylation. These data indicate that the Lyn mutation in NOD neutrophils is likely responsible for dysregulation of neutrophil adhesion and directed migration, implying the role of Lyn in modulating diabetic patient's susceptibility to bacterial and fungal infections. J. Cell. Physiol. 232: 1689-1695, 2017. © 2016 Wiley Periodicals, Inc.

Immune Cell Traffic in the Brain: Blundering and Migration of Autoreactive T Lymphocytes

The migration of an autoreactive CD4 T lymphocyte across the blood-brain barrier (BBB) represents a crucial step in the pathogenesis of multiple sclerosis (MS) and its animal model, experimental autoimmune encephalitis (EAE). For a naive, autoreactive T lym phocyte to enter the CNS, it must first be activated by antigen presented by an anti gen-presenting cell in peripheral lymphoid tissue. Effector lymphocytes home to activated endothelium in the CNS and other tissues through the binding of the integrins very late antigen 4 (VLA-4) and leukocyte function antigen 1 (LFA-1) to vascular cell adhesion molecule (VCAM-1) and intercellular cell adhesion molecule (lCAM-1), respectmely. Al though VLA-4 and LFA-1 clearly mediate T cell recruitment in a region of established inflammation, the mechanisms of early lymphocyte entry prior to endothelial activation remain unclear. Here, it is hypothesized that initiation of an inflammatory focus in CNS autoimmune disease is mediated by a novel cell adhesion pathway that is VLA-4-inde pendent and permits autoreactive lymphocytes to randomly "blunder" into the brain. An understanding of these mechanisms is crucial to the development of antigen-nonspecific therapies for MS. NEUROSCIENTIST 3:207-210, 1997

Cerebrovascular adaptations to chronic hypoxia in the growth restricted lamb

Chronic moderate hypoxia induces angiogenic adaptation in the brain, reflecting a modulatory role for oxygen in determining cerebrovascular development. Chronic intrauterine fetal hypoxia, such as occurs in intrauterine growth restriction (IUGR) is likely to lead to a reduction in oxygen delivery to the brain and long-term neurological abnormalities. Thus we investigated whether vascular remodeling and vascular abnormalities were evident in the brain of IUGR newborn lambs that were chronically hypoxic in utero. Single uterine artery ligation (SUAL) surgery was performed in fetuses at ∼ 105 days gestation (term ∼ 145 days) to induce placental insufficiency and IUGR. Ewes delivered naturally at term and lambs were euthanased 24h later. IUGR brains (n = 9) demonstrated a significant reduction in positive staining for the number of blood vessels (laminin immunohistochemistry) compared with control (n = 8): from 1650 ± 284 to 416 ± 47 cells/mm(2) in subcortical white matter (SCWM) 1793 ± 298 to 385 ± 20 cells/mm(2) in periventricular white matter (PVWM), and 1717 ± 161 to 405 ± 84 cells/mm(2) in the subventricular zone (SVZ). The decrease in vascular density was associated with a significant decrease in VEGF immunoreactivity. The percentage of blood vessels exhibiting endothelial cell proliferation (Ki67 positive) varied regionally between 14 to 22% in white matter of control lambs, while only 1-3% of blood vessels in IUGR brains showed proliferation. A 66% reduction in pericyte coverage (α-SMA and desmin) of blood vessels was observed in SCWM, 71% in PVWM, and 73% in SVZ of IUGR lambs, compared to controls. A reduction in peri-vascular astrocytes (GFAP and laminin) was also observed throughout the white matter of IUGR lambs, and extravasation of albumin into the brain parenchyma was present, indicative of increased permeability of the blood brain barrier. Chronic hypoxia associated with IUGR results in a reduction in vascular density in the white matter of IUGR newborn brains. Vascular pericyte coverage and peri-vascular astrocytes, both of which are essential for stabilisation of blood vessels and the maintenance of vascular permeability, were also decreased in the white matter of IUGR lambs. In turn, these vascular changes could lead to inadequate oxygen supply and contribute to under-perfusion and increased vulnerability of white matter in IUGR infants.

Multilevel regulation of matrix metalloproteinases in tissue homeostasis indicates their molecular specificity in vivo

The matrix metalloproteinases (MMPs) play a crucial role in irreversible remodeling of the extracellular matrix (ECM) in normal homeostasis and pathological states. Accumulating data from various studies strongly suggest that MMPs are tightly regulated, starting from the level of gene expression all the way to zymogen activation and endogenous inhibition, with each level controlled by multiple factors. Recent in vivo findings indicate that cell-ECM and cell-cell interactions, as well as ECM bio-active products, contribute an additional layer of regulation at all levels, indicating that individual MMP expression and activity in vivo are highly coordinated and tissue specific processes.

Effects of monocyte-endothelium interactions on the expression of type IV collagenases in monocytes

The adhesion of monocytes to endothelial cells is one of the early stages in the development of atherosclerosis. The expression of type IV collagenases, which include matrix metalloproteinase (MMP)-2 and MMP-9, in monocytes is hypothesized to play an important role in monocyte infiltration and transformation into foam cells. The aim of the present study was to examine the effects of monocyte-endothelium interactions on the expression levels of type IV collagenases and their specific inhibitors in monocytes, and to investigate the roles of tumor necrosis factor (TNF)-α and interleukin (IL)-1β in this process. Monocytes were single-cultured or co-cultured with endothelial cells. The expression of the type IV collagenases, MMP-2 and MMP-9, and their specific inhibitors, tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2, in monocytes was determined by immunohistochemistry followed by image analysis. The expression levels of MMP-2 and MMP-9 were found to be low in the single-culture monocytes, but increased significantly when the monocytes and endothelial cells were co-cultured. However, treatment with monoclonal TNF-α or IL-1β antibodies partially inhibited the upregulated expression of MMP-2 and MMP-9 in the co-cultured monocytes. Expression of TIMP-1 and TIMP-2 was observed in the single monocyte culture, and a small increase in the expression levels was observed when the monocytes were co-cultured with endothelial cells. Therefore, monocyte-endothlium interactions were shown to increase the expression of type IV collagenases in monocytes, resulting in the loss of balance between MMP-2 and -9 with TIMP-1 and -2. In addition, TNF-α and IL-1β were demonstrated to play important roles in this process.

Nitric oxide-matrix metaloproteinase-9 interactions: biological and pharmacological significance--NO and MMP-9 interactions

Nitric oxide (NO) and matrix metalloproteinase 9 (MMP-9) levels are found to increase in inflammation states and in cancer, and their levels may be reciprocally modulated. Understanding interactions between NO and MMP-9 is of biological and pharmacological relevance and may prove crucial in designing new therapeutics. The reciprocal interaction between NO and MMP-9 have been studied for nearly twenty years but to our knowledge, are yet to be the subject of a review. This review provides a summary of published data regarding the complex and sometimes contradictory effects of NO on MMP-9. We also analyse molecular mechanisms modulating and mediating NO-MMP-9 interactions. Finally, a potential therapeutic relevance of these interactions is presented.

Targeting matrix metalloproteinase activity and expression for the treatment of viral myocarditis

Infectious agents including viruses can infect the heart muscle, resulting in the development of heart inflammation called myocarditis. Chronic myocarditis can lead to dilated cardiomyopathy (DCM). DCM develops from the extensive extracellular matrix (ECM) remodeling caused by myocarditis and may result in heart failure. Epidemiological data for viral myocarditis has long suggested a worse pathology in males, with more recent data demonstrating sex-dependent pathogenesis in DCM as well. Matrix metalloproteinases (MMPs), long known modulators of the extracellular matrix, have important roles in mediating heart inflammation and remodeling during disease and in convalescence. This ability of MMPs to control both the inflammatory response and ECM remodeling during myocarditis makes them potential drug targets. In this review, we analyze the role of MMPs in mediating myocarditis/DCM disease progression, their sex-dependent expression, and their potential as drug targets during viral myocarditis and DCM.

Location, location, location: the impact of migratory heterogeneity on T cell function

T cell migration is crucial for an effective adaptive immune response to invading pathogens. Naive and memory T cells encounter pathogen antigens, become activated, and differentiate into effector cells in secondary lymphoid tissues, and then migrate to the site(s) of infection where they exert effector activities that control and eliminate pathogens. To achieve activation, efficient effector function, and good memory formation, T cells must traffic between lymphoid and non-lymphoid tissues within the body. This complex process is facilitated by chemokine receptors, selectins, CD44, and integrins that mediate the interactions of T cells with the environment. The expression patterns of these migration receptors (MR) dictate the tissues into which the effector T cells migrate and enable them to occupy specific niches within the tissue. While MR have been considered primarily to facilitate cell movement, we highlight how the heterogeneity of signaling through these receptors influences the function and fate of T cells in situ. We explore what drives MR expression heterogeneity, how this affects migration, and how this impacts T cell effector function and memory formation.

Matrix Metalloproteinases in Cerebral Vasospasm following Aneurysmal Subarachnoid Hemorrhage

Delayed cerebral vasospasm is a significant cause of morbidity and mortality following aneurysmal subarachnoid hemorrhage (SAH). While the cellular mechanisms underlying vasospasm remain unclear, it is believed that inflammation may play a critical role in vasospasm. Matrix metalloproteinasees (MMPs) are a family of extracellular and membrane-bound proteases capable of degrading the blood-rain barrier (BBB). As such, MMP upregulation following SAH may result in a proinflammatory extravascular environment capable of inciting delayed cerebral vasospasm. This paper presents an overview of MMPs and describes existing data pertinent to delayed cerebral vasospasm.

TWEAK/Fn14 pathway modulates properties of a human microvascular endothelial cell model of blood brain barrier

BACKGROUND

The TNF ligand family member TWEAK exists as membrane and soluble forms and is involved in the regulation of various human inflammatory pathologies, through binding to its main receptor, Fn14. We have shown that the soluble form of TWEAK has a pro-neuroinflammatory effect in an animal model of multiple sclerosis and we further demonstrated that blocking TWEAK activity during the recruitment phase of immune cells across the blood brain barrier (BBB) was protective in this model. It is now well established that endothelial cells in the periphery and astrocytes in the central nervous system (CNS) are targets of TWEAK. Moreover, it has been shown by others that, when injected into mice brains, TWEAK disrupts the architecture of the BBB and induces expression of matrix metalloproteinase-9 (MMP-9) in the brain. Nevertheless, the mechanisms involved in such conditions are complex and remain to be explored, especially because there is a lack of data concerning the TWEAK/Fn14 pathway in microvascular cerebral endothelial cells.

METHODS

In this study, we used human cerebral microvascular endothelial cell (HCMEC) cultures as an in vitro model of the BBB to study the effects of soluble TWEAK on the properties and the integrity of the BBB model.

RESULTS

We showed that soluble TWEAK induces an inflammatory profile on HCMECs, especially by promoting secretion of cytokines, by modulating production and activation of MMP-9, and by expression of cell adhesion molecules. We also demonstrated that these effects of TWEAK are associated with increased permeability of the HCMEC monolayer in the in vitro BBB model.

CONCLUSIONS

Taken together, the data suggest a role for soluble TWEAK in BBB inflammation and in the promotion of BBB interactions with immune cells. These results support the contention that the TWEAK/Fn14 pathway could contribute at least to the endothelial steps of neuroinflammation.

Inhibition of neutrophil migration by a selective inhibitor of matrix metalloproteinase: analysis by intravital microscopy

Observation of the microcirculation of the hamster cheek pouch by intravital microscopy revealed five steps of neutrophil migration from the venules after topical application of leukotriene B₄ to the microvasculature: rolling along the venular wall (Step 1), adhesion to it (Step 2), disappearance from the vascular lumen (Step 3), presence between the endothelial cells and the subendothelial basement membrane (Step 4) and passage through the basement membrane (Step 5). The present study was performed to examine whether a metalloproteinase inhibitor inhibits neutrophil migration at any of the above five steps. Chymostatin and leupeptin did not inhibit any of these five steps. In contrast, FN-439, a selective inhibitor of matrix metalloproteinase, reduced the number of neutrophils in the perivascular space without affecting Steps 1 to 3. It was concluded that neutrophils may use metalloproteinase (collagenase/gelatinase) to penetrate the subendothelial basement membrane.

Two preferentially expressed proteins protect vascular endothelial cells from an attack by peptide-specific CTL

Vascular endothelial cells (EC) are an exposed tissue with intimate contact with circulating Ag-specific CTL. Experimental in vitro and clinical data suggested that endothelial cells present a different repertoire of MHC class I-restricted peptides compared with syngeneic leukocytes or epithelial cells. This endothelial-specific peptide repertoire might protect EC from CTL-mediated cell death. The HLA-A*02-restricted peptide profile of human EC and syngeneic B lymphoblastoid cells was biochemically analyzed and compared. For EC selective peptides, source protein expression, peptide binding affinity, and peptide-HLA-A*02 turnover were measured. The significance of abundant peptide presentation for target cell recognition by immunodominant CTL was tested by small interfering RNA treatment of EC to knock down the source proteins. High amounts of two peptides, PTRF(56-64) and CD59(106-114), were consistently detected in EC. This predominance of two endothelial peptides was explained by cell type-specific source protein expression that compensated for poor HLA-A*02 binding affinity and short half-live of peptide/HLA-A*02 complexes. Knocking down the source proteins containing the abundant endothelial peptide motifs led to a nearly 100-fold increase of surface expression of SMCY(311-319), an immunodominant minor histocompatibility Ag, as detected by cytotoxicity assays using SMCY(311-319)-specific CTL. We conclude that EC express and present preferentially two distinct HLA-A*02-restricted peptides at extraordinary high levels. These abundant self-peptides may protect EC from CTL-mediated lysis by competing for HLA-A*02 binding sites with immunodominant scarcely expressed antigenic peptides.

Lessons from a mouse model characterizing features of vascular cognitive impairment with white matter changes

With the demographic shift in age in advanced countries inexorably set to progress in the 21st century, dementia will become one of the most important health problems worldwide. Vascular cognitive impairment is the second most common type of dementia after Alzheimer's disease and is frequently responsible for the cognitive decline of the elderly. It is characterized by cerebrovascular white matter changes; thus, in order to investigate the underlying mechanisms involved in white matter changes, a mouse model of chronic cerebral hypoperfusion has been developed, which involves the narrowing of the bilateral common carotid arteries with newly designed microcoils. The purpose of this paper is to provide a comprehensive summary of the achievements made with the model that shows good reproducibility of the white matter changes characterized by blood-brain barrier disruption, glial activation, oxidative stress, and oligodendrocyte loss following chronic cerebral hypoperfusion. Detailed characterization of this model may help to decipher the substrates associated with impaired memory and move toward a more integrated therapy of vascular cognitive impairment.

Vascular cell adhesion molecule-1 expression and signaling during disease: regulation by reactive oxygen species and antioxidants

The endothelium is immunoregulatory in that inhibiting the function of vascular adhesion molecules blocks leukocyte recruitment and thus tissue inflammation. The function of endothelial cells during leukocyte recruitment is regulated by reactive oxygen species (ROS) and antioxidants. In inflammatory sites and lymph nodes, the endothelium is stimulated to express adhesion molecules that mediate leukocyte binding. Upon leukocyte binding, these adhesion molecules activate endothelial cell signal transduction that then alters endothelial cell shape for the opening of passageways through which leukocytes can migrate. If the stimulation of this opening is blocked, inflammation is blocked. In this review, we focus on the endothelial cell adhesion molecule, vascular cell adhesion molecule-1 (VCAM-1). Expression of VCAM-1 is induced on endothelial cells during inflammatory diseases by several mediators, including ROS. Then, VCAM-1 on the endothelium functions as both a scaffold for leukocyte migration and a trigger of endothelial signaling through NADPH oxidase-generated ROS. These ROS induce signals for the opening of intercellular passageways through which leukocytes migrate. In several inflammatory diseases, inflammation is blocked by inhibition of leukocyte binding to VCAM-1 or by inhibition of VCAM-1 signal transduction. VCAM-1 signal transduction and VCAM-1-dependent inflammation are blocked by antioxidants. Thus, VCAM-1 signaling is a target for intervention by pharmacological agents and by antioxidants during inflammatory diseases. This review discusses ROS and antioxidant functions during activation of VCAM-1 expression and VCAM-1 signaling in inflammatory diseases.

Interference with islet-specific homing of autoreactive T cells: an emerging therapeutic strategy for type 1 diabetes

Pathogenesis of type 1 diabetes involves the activation of autoimmune T cells, consequent homing of activated lymphocytes to the pancreatic islets and ensuing destruction of insulin-producing b cells. Interaction between activated lymphocytes and endothelial cells in the islets is the hallmark of the homing process. Initial adhesion, firm adhesion and diapedesis of lymphocytes are the three crucial steps involved in the homing process. Cell-surface receptors including integrins, selectins and hyaluronate receptor CD44 mediate the initial steps of homing. Diapedesis relies on a series of proteolytic events mediated by matrix metalloproteinases. Here, molecular mechanisms governing transendothelial migration of the diabetogenic effector cells are discussed and resulting pharmacological strategies are considered.

Matrix metalloproteinases in cytotoxic lymphocytes impact on tumour infiltration and immunomodulation

To efficiently combat solid tumours, endogenously or adoptively transferred cytotoxic T cells and natural killer (NK) cells, need to leave the vasculature, traverse the interstitium and ultimately infiltrate the tumour mass. During this locomotion and migration in the three dimensional environment many obstacles need to be overcome, one of which is the possible impediment of the extracellular matrix. The first and obvious one is the sub-endothelial basement membrane but the infiltrating cells will also meet other, both loose and tight, matrix structures that need to be overridden. Matrix metalloproteinases (MMPs) are believed to be one of the most important endoprotease families, with more than 25 members, which together have function on all known matrix components. This review summarizes what is known on synthesis, expression patterns and regulation of MMPs in cytotoxic lymphocytes and their possible role in the process of tumour infiltration. We also discuss different functions of MMPs as well as the possible use of other lymphocyte proteases for matrix degradation.

Berberine attenuates experimental autoimmune encephalomyelitis in C57 BL/6 mice

Background

Berberine, an isoquinoline derivative alkaloid, has a wide range of pharmacological properties and is considered to have anti-inflammatory and neuroprotective effects. However, there are no reports about the effects and mechanisms of berberine in experimental autoimmune encephalomyelitis (EAE), an established model of multiple sclerosis (MS).

Methodology/Principal Findings

Female C57 BL/6 mice immunized with myelin oligodendrocyte glycoprotein 35–55 amino acid peptide were treated with berberine at the day of disease onset and medication was administered daily until mice were sacrificed. Blood–brain barrier (BBB) permeability and the alteration of matrix metalloproteinase-2 (MMP-2, 72 kDa) and matrix metalloproteinase-9 (MMP-9, 92 kDa) in the brain and cerebrospinal fluid (CSF) of EAE mice were detected by quantitative measurement for Evan's blue (EB) content, Western blot and gelatin zymography respectively. The results showed that berberine attenuated clinical and pathological parameters of EAE, reduced the permeability of BBB, inhibited the activity and expression of MMP-9 but not MMP-2 in the CSF and brain of EAE mice.

Conclusions/Significance

These findings suggest that berberine is effective to attenuate the clinical severity of EAE in C57 BL/6 mice by reducing the permeability of BBB, decreasing the expression and activity of MMP-9, and decreasing the inflammatory infiltration. We think that berberine might be a potential therapeutic agent for MS.

Blockade of TGF-β by catheter-based local intravascular gene delivery does not alter the in-stent neointimal response, but enhances inflammation in pig coronary arteries

BACKGROUND

Extracellular matrix (ECM) accumulation significantly contributes to in-stent restenosis. In this regard, transforming growth factor (TGF)-β, a positive regulator of ECM deposition, may be implicated in in-stent restenosis. The goal of this study was to assess the effect of blockade of TGF-β on stent-induced restenosis in porcine coronary arteries.

METHODS

An adenovirus expressing the ectodomain of the TGF-β type II receptor (AdTβ-ExR) was applied onto a coronary arterial segment of a pig (n=10) using an Infiltrator, followed by stent deployment. Controls consisted of adenoviruses expressing β-galactosidase (AdLacZ) or phosphate-buffered saline (PBS) applied onto the other segment (n=10) of the same pig.

RESULTS

Computer-based pathological morphometric analysis of stented coronary arteries, performed 4 weeks after stenting, demonstrated no significant difference in morphometric parameters such as in-stent neointimal area and % area stenosis between the AdTβ-ExR group and control (n=7 for each). However the AdTβ-ExR group had increased neointimal cell density, infiltration of inflammatory cells mostly consisting of CD3+ T cell, accumulation of hyaluronan, cell proliferation rate, and adventitial matrix metalloproteinase-1 (MMP-1) expression compared with control. The expression of connective tissue growth factor mRNA, measured by reverse transcription PCR, in cultured rat arterial smooth muscle cells was inhibited by AdTβ-ExR at moi 60.

CONCLUSIONS

Blockade of TGF-β by catheter-based local intravascular gene delivery does not reduce stent-induced neointima formation 4 weeks after stenting in spite of modest inhibition of ECM accumulation, but it induces vascular inflammation and associated pathological changes that may potentially aggravate lesion progression.

The cloning and expression of matrix metalloproteinase-2 and tissue inhibitor of matrix metalloproteinase 2 in normal canine lymph nodes and in canine lymphoma

Matrix metalloproteinase-2 (MMP-2) and its inhibitor, tissue inhibitor of matrix metalloproteinase 2 (TIMP2), are known to be important in cancer. The purposes of this study were to determine the cDNA sequence of canine MMP-2 and to investigate the expression patterns of MMP-2 and TIMP2 in normal canine lymph nodes and spontaneously arising canine lymphomas. We cloned and sequenced a PCR product containing most (1901 base pairs) of the coding sequence of canine MMP-2 that translates into a 623 amino acid protein. The cDNA and deduced amino acid sequences are highly homologous to those of other mammalian species. Canine MMP-2 and TIMP2 mRNAs were detectable in the majority of normal lymph node and lymphomatous samples evaluated. No statistical difference was identified when comparing the expression of either gene with regard to normal versus neoplastic nodes, nodal versus extranodal lymphoma, lymphoma grade, or B versus T cell immunophenotype.

Tanshinone IIA downregulates the CD40 expression and decreases MMP-2 activity on atherosclerosis induced by high fatty diet in rabbit

Tanshinone IIA (Tan IIA) is a member of the major lipophilic components abstracted from the root of Salvia miltiorrhiza Bunge and has the capacity of anti-atherosclerosis. To investigate the potential mechanism, we established an animal model by giving high fatty diet to rabbits and Tan IIA was given in different dose. Then, superoxide dismutase (SOD) activity and the malondialdehyde (MDA) level in serum were detected using spectrophotometry; cluster of differentiation 40 (CD40) expression of cellular membrane fraction of aortas and matrix metalloproteinase-2 (MMP-2) activity of total protein extract of aortas were detected by Western Blotting and Zymography, respectively. Compared with the control group, the level of MDA, the expression of CD40 and the MMP-2 activity were increased while the SOD activity was decreased significantly in model group. After Tan IIA administration, the SOD activity was significantly increased while the level of MDA was decreased; both the expression of CD40 and the activity of MMP-2 were decreased. It is suggested that Tan IIA not only inhibits the oxidation but also suppresses the inflammation in atherosclerotic lesion. Our data suggest that not only anti-oxidation but also anti-inflammation by decrease the expression of CD40 and MMP-2 activity maybe the potential mechanisms by which Tan IIA anti-atherosclerosis.

PECAM-1: a multifaceted regulator of megakaryocytopoiesis

PECAM-1 (CD31) knockout (KO) mice exhibit excessive megakaryocytopoiesis accompanied by increased numbers of megakaryocytes associated with the stromal niche rather than the vascular niche. During earlier stages of megakaryocytopoiesis in KO marrow, an expanded Lin(-)Sca-1(+) c-kit(+) hematopoietic stem cell (HSC) population and increased quiescent Lin(-) progenitor pool were identified. During the later stages of megakaryocytopoiesis, CD31KO megakaryocytes exhibited abnormal adhesion/transmigration behaviors. Lastly, KO animals exhibited excessive splenic extramedullary megakaryocytopoiesis, which likely compensates for the impaired marrow megakaryocytopoiesis, resulting in normal peripheral platelet number. Thus, PECAM-1 modulates megakaryocytopoiesis in a hierarchic manner, functioning as a thermostat to "fine-tune" megakaryocytopoiesis.

Hydrogen peroxide activation of endothelial cell-associated MMPs during VCAM-1-dependent leukocyte migration

Leukocyte migration from the blood into tissues is vital for immune surveillance and inflammation. Specificity for the site of leukocyte migration is determined by the combination and concentration of adhesion molecules, cytokines and chemokines in the microenvironment. Leukocytes bound at sites of extravasation migrate within minutes. We have focused on the function of the adhesion molecule VCAM-1 and have reported an active function for the endothelium during VCAM- 1-dependent leukocyte migration. VCAM-1 activates endothelial cell NADPH oxidase followed by the generation of 1 microM H2O2. This stimulates endothelial cell-associated matrix metalloproteinase (MMP) activity in minutes, consistent with the time for lymphocyte migration. The endothelial cell NADPH oxidase and endothelial cell MMP activities are required for VCAM-1-dependent lymphocyte migration as determined by scavenging of ROS, by pharmacologic or antisense inhibition of NADPH oxidase and by pharmacologic inhibition of endothelial cell MMPs. Furthermore, antioxidants block VCAM-1 activation of MMPs. In vivo, administration of the antioxidant bilirubin blocks VCAM-1-dependent leukocyte migration into the lung in experimental asthma. In summary, endothelial cells are not simply a scaffold for leukocyte adhesion. Instead, endothelial cells have an active function during VCAM-1-dependent leukocyte transendothelial migration.

MMP-2 and MMP-9 levels in peripheral blood after subarachnoid hemorrhage

MMPs play an important role in ischemic and hemorrhagic stroke. We analyzed replicate serum samples from 20 normal healthy individuals to assess reproducibility of MMP determinations, and found that MMP-2 and MMP-9 determinations were quite consistent. We then studied the serum levels of MMP-2 and MMP-9 in patients suffering from subarachnoid hemorrhage (SAH), another stroke subtype. Serum MMP-2 and MMP-9 levels from SAH patients were measured sequentially using gelatine zymography in 11 patients after acute SAH. The occurrence of intracerebral aneurysms and vasospasms and the initial Hunt and Hess score were analysed in relation to MMP-levels. MMP-2 levels are significantly decreased while MMP-9 levels are increased in SAH patients relative to controls. MMP-2 levels remain depressed out to day 12 post SAH, but MMP-9 levels may recover by day 12.

The role of genetic variants of matrix metalloproteinases in coronary and carotid atherosclerosis

Current evidence suggests that matrix metalloproteinases (MMPs) have a role in early atherosclerosis, plaque rupture and myocardial infarction. Polymorphisms in MMP genes have been examined for associations with atherosclerosis, but interpretation is complicated by methodological issues. This article presents a systematic review of these association studies and a meta-analysis of available data for polymorphisms where a sufficient number of studies was available. The 5A allele of the MMP3 5A/6A polymorphism was associated with acute myocardial infarction (odds ratio (OR) 1.26, 95% confidence interval (CI) 1.1 to 1.4, p<0.001), suggesting its role in plaque rupture. There was no association with the functional MMP9 -1562C/T polymorphism (OR 1.11, 95% CI 1.0 to 1.3, p = 0.18). Current data provide evidence for the role of MMP3 polymorphism in plaque destabilisation, but elucidation of the role of other MMP gene variants in atherosclerosis will depend on better study design, including a larger sample size, extensive screening of individual genes with haplotype analysis and replication of studies to avoid publication bias.

Tissue inhibitor of metalloproteinase-1 (TIMP-1) is an independent predictor of all-cause mortality, cardiac mortality, and myocardial infarction

BACKGROUND

Matrix metalloproteinases and their inhibitors have been implicated in both vascular and ventricular remodeling, and in atherosclerotic plaque rupture. The prognostic value of plasma tissue inhibitor of metalloproteinase-1 (TIMP-1) levels in patients with established or suspected coronary artery disease is unknown.

METHODS

Tissue inhibitor of metalloproteinase-1 and matrix metalloproteinase-9 (MMP-9) levels, along with a number of other established biomarkers, were measured in 389 male patients undergoing coronary angiography at a Veterans Administration Medical Center. The patients were then followed prospectively for the occurrence of all-cause mortality, cardiac mortality, and myocardial infarction (MI).

RESULTS

Follow-up data at 24 months were available for 97% of the patients. For the entire cohort of patients, TIMP-1 was the only biomarker to independently predict all-cause mortality and MI. In addition, the ratio of TIMP-1 to matrix metalloproteinase-9 was independently predictive of cardiac mortality at 24 months. The 24-month survival rates for patients in the lower quartile (< 66.5 ng/mL), interquartile (66.5-100 ng/mL), and upper quartile (> 100 ng/mL) of plasma TIMP-1 values were 95.3%, 89.3%, and 72.2%, respectively (P < .001). Furthermore, when patients with chest pain were risk stratified into those with and without an acute coronary syndrome, TIMP-1 remained an independent predictor of all-cause mortality in both subgroups.

CONCLUSIONS

In a cohort of male patients undergoing coronary angiography, a single baseline determination of plasma TIMP-1 is independently predictive of the subsequent risk of death and MI.

Immune cell migration in inflammation: present and future therapeutic targets

The burgeoning field of leukocyte trafficking has created new and exciting opportunities in the clinic. Trafficking signals are being defined that finely control the movement of distinct subsets of immune cells into and out of specific tissues. Because the accumulation of leukocytes in tissues contributes to a wide variety of diseases, these 'molecular codes' have provided new targets for inhibiting tissue-specific inflammation, which have been confirmed in the clinic. However, immune cell migration is also critically important for the delivery of protective immune responses to tissues. Thus, the challenge for the future will be to identify the trafficking molecules that will most specifically inhibit the key subsets of cells that drive disease processes without affecting the migration and function of leukocytes required for protective immunity.

Matrix metalloproteinases in cerebrovascular diseases

Matrix metalloproteinases are important factors for tissue remodelling and are activated during several physiological and pathological conditions, including cerebrovascular diseases. We give an overview of the structure, production and physiological effects of these widely distributed proteases and describe the genetic background and regulation pathways. In particular, we discuss the role of matrix metalloproteinases in vascular remodelling concerning ischaemic stroke, brain haemorrhage, vascular dementia, carotid artery plaques and cerebral aneurysms.

Omega-3 Fatty Acids and the Regulation of Expression of Endothelial Pro-Atherogenic and Pro-Inflammatory Genes

By partially replacing the corresponding omega-6 analogues in membrane phospholipids, omega-3 fatty acids have been shown to decrease the transcriptional activation of genes--e.g., adhesion molecules, chemoattractants, inflammatory cytokines--involved in endothelial activation in response to inflammatory and pro-atherogenic stimuli. This regulation occurs, at least in part, through a decreased activation of the nuclear factor-kappaB system of transcription factors, secondary to decreased generation of intracellular hydrogen peroxide. Such regulation by omega-3 fatty acids is likely linked to the presence of a higher number of double bonds in the fatty acid chain in omega-3 compared with omega-6 fatty acids. By similar mechanisms, omega-3 fatty acids have been recently shown to reduce gene expression of cyclooxygenase-2, an inflammatory gene involved, through the activation of some metalloproteinases, in plaque angiogenesis and plaque rupture. The quenching of gene expression of pro-inflammatory pro-atherogenic genes by omega-3 fatty acids has consequences on the extent of leukocyte adhesion to vascular endothelium, early atherogenesis and later stages of plaque development and plaque rupture, ultimately yielding a plausible comprehensive explanation for the vasculoprotective effects of these nutrients.

Membrane type 1–matrix metalloproteinase is involved in migration of human monocytes and is regulated through their interaction with fibronectin or endothelium

Membrane type 1–matrix metalloproteinase (MT1-MMP) is involved in endothelial and tumor-cell migration, but its putative role in leukocyte migration has not been characterized yet. Here, we demonstrate that anti–MT1-MMP monoclonal antibody (mAb) impaired monocyte chemotactic protein-1 (MCP-1)–stimulated monocyte migration on fibronectin (FN), vascular cell adhesion molecule-1 (VCAM-1), and intercellular adhesion molecule-1 (ICAM-1). In addition, monocyte transmigration through tumor necrosis factor-α (TNF-α)–activated endothelium is also inhibited by anti–MT1-MMP mAb. Therefore, regulation of MT1-MMP in human peripheral blood monocytes was investigated. First, MT1-MMP clustering was observed at motility-associated membrane protrusions of MCP-1–stimulated monocytes migrating on FN, VCAM-1, or ICAM-1 and at the leading edge, together with profilin, of monocytes transmigrating through activated endothelial cells. In addition, up-regulation of MT1-MMP expression was induced in human monocytes upon attachment to FN in a manner dependent on α4β1 and α5β1 integrins. Binding of monocytes to TNF-α–activated human endothelial cells as well as to VCAM-1 or ICAM-1 also resulted in an increase of MT1-MMP expression. These findings correlated with an enhancement of MT1-MMP fibrinolytic activity in monocytes bound to FN, VCAM-1, or ICAM-1. Our data show that MT1-MMP is required during human monocyte migration and endothelial transmigration and that MT1-MMP localization, expression, and activity are regulated in monocytes upon contact with FN or endothelial ligands, pointing to a key role of MT1-MMP in monocyte recruitment during inflammation.

A matrix metalloproteinase inhibitor promotes granuloma formation during the early phase of Mycobacterium tuberculosis pulmonary infection

OBJECTIVE

The host response to pulmonary Mycobacterium tuberculosis (Mtb) infection results in granuloma formation in an effort to limit infection, but the host immune cells also provide an environment in which Mtb persists. Granuloma formation requires immune cell infiltration and concurrent extensive remodeling of pulmonary tissue which we hypothesize to be the result of increased matrix metalloproteinases (MMP) activity.

DESIGN

C57BL/6 mice infected with virulent Mtb (H37Rv) via intratracheal inoculation were treated with a synthetic inhibitor of MMP activity (BB-94). Mice were assessed for colony forming units, granuloma morphology, leukocyte recruitment and cytokine levels over 90 days of infection.

RESULTS

BB-94 treated mice had significantly decreased numbers of pulmonary and blood-borne Mtb early during disease, increased collagen deposition within early granulomas and significantly decreased pulmonary leukocyte recruitment when compared to vehicle-treated, Mtb-infected mice. Cytokine expression did not differ significantly between groups.

CONCLUSION

Events of early granuloma formation can be modified by inhibiting MMP activity, by decreasing leukocyte recruitment, a major source of MMPs during infection, enhancing the establishment of granulomas and decreasing blood-borne dissemination of Mtb.

Induction of matrix metalloproteinase-9 in murine eosinophilic meningitis caused by Angiostrongylus cantonensis

Matrix metalloproteinases (MMP) have been implicated in the pathogenesis of various inflammatory diseases of the central nervous system. In the present study, a gelatinase was found to be induced in parasitic meningitis caused, in mice, by Angiostrongylus cantonensis. The enzyme had a molecular weight of about 94 kDa, showed maximal activity between pH 6 and pH 8, and was clearly inhibited by EDTA and 1,10-phenanthroline but not by leupeptin or phenylmethanesulphonyl fluoride. When samples of cerebrospinal fluid from the mice with meningitis were blotted with specific antiserum against gelatinase B (MMP-9), a 94-kDa immunopositive band was observed, indicating that the induced gelatinase was MMP-9. In the A. cantonensis-infected mice, immuno-histochemistry demonstrated MMP-9 within the endothelial cells lining the vascular spaces of the brain and in the leucocytes that were found, in aggregates, in the subarachnoid space. Leucocytes may play an important role in the pathogenesis of inflammatory disorders of the central nervous system.

The role of chemokines and extracellular matrix components in the migration of T lymphocytes into three-dimensional substrata

The role of chemokines and their interactions with extracellular matrix components (ECM) or the capacity of T cells to migrate into and accumulate within three-dimensional (3D) collagen type 1 substrata was studied. We examined the influence of chemokines and fibronectin on the infiltration properties of non-infiltrative (do not migrate into 3D substrata) and spontaneously infiltrative (migrate into 3D substrata) T-cell lines. Infiltrative and non-infiltrative T-acute lymphocytic leukaemic cell lines exhibited no consistent differences with respect to the expression of various chemokine receptors or beta(1)-integrins. Chemokines presented inside the collagen increased the depth of migration of infiltrative T-cell lines, but did not render non-infiltrative T-cell lines infiltrative, although they augmented the attachment of non-infiltrative T-cell lines to the upper surface of the collagen. The presence of fibronectin inside the collagen did not render non-infiltrative T-cell lines infiltrative, but markedly augmented the migration of 'infiltrative' T-cell lines into collagen. Both infiltrative and non-infiltrative T-cell lines showed migratory responses to chemokines in Boyden assays (migration detected on 2D substrata). These results indicate that the process of T-cell infiltration/migration into 3D substrata depends on a tissue penetration mechanism distinguishable from migration on 2D substrata and that the basic capacity of T cells to infiltrate is independent of chemokines and ECM components applied as attractants.