Activated protein C directly activates human endothelial gelatinase A

A recombinant signalling-selective activated protein C that lacks anticoagulant activity is efficacious and safe in cutaneous wound preclinical models

Various preclinical and clinical studies have demonstrated the robust wound healing capacity of the natural anticoagulant activated protein C (APC). A bioengineered APC variant designated 3K3A-APC retains APC's cytoprotective cell signalling actions with <10% anticoagulant activity. This study was aimed to provide preclinical evidence that 3K3A-APC is efficacious and safe as a wound healing agent. 3K3A-APC, like wild-type APC, demonstrated positive effects on proliferation of human skin cells (keratinocytes, endothelial cells and fibroblasts). Similarly it also increased matrix metollaproteinase-2 activation in keratinocytes and fibroblasts. Topical 3K3A-APC treatment at 10 or 30 μg both accelerated mouse wound healing when culled on Day 11. And at 10 μg, it was superior to APC and had half the dermal wound gape compared to control. Further testing was conducted in excisional porcine wounds due to their congruence to human skin. Here, 3K3A-APC advanced macroscopic healing in a dose-dependent manner (100, 250 and 500 μg) when culled on Day 21. This was histologically corroborated by greater collagen maturity, suggesting more advanced remodelling. A non-interference arm of this study found no evidence that topical 3K3A-APC caused either any significant systemic side-effects or any significant leakage into the circulation. However the female pigs exhibited transient and mild local reactions after treatments in week three, which did not impact healing. Overall these preclinical studies support the hypothesis that 3K3A-APC merits future human wound studies.

Destroy to Rebuild: The Connection Between Bone Tissue Remodeling and Matrix Metalloproteinases

Bone is a dynamic organ that undergoes constant remodeling, an energetically costly process by which old bone is replaced and localized bone defects are repaired to renew the skeleton over time, thereby maintaining skeletal health. This review provides a general overview of bone’s main players (bone lining cells, osteocytes, osteoclasts, reversal cells, and osteoblasts) that participate in bone remodeling. Placing emphasis on the family of extracellular matrix metalloproteinases (MMPs), we describe how: (i) Convergence of multiple protease families (including MMPs and cysteine proteinases) ensures complexity and robustness of the bone remodeling process, (ii) Enzymatic activity of MMPs affects bone physiology at the molecular and cellular levels and (iii) Either overexpression or deficiency/insufficiency of individual MMPs impairs healthy bone remodeling and systemic metabolism. Today, it is generally accepted that proteolytic activity is required for the degradation of bone tissue in osteoarthritis and osteoporosis. However, it is increasingly evident that inactivating mutations in MMP genes can also lead to bone pathology including osteolysis and metabolic abnormalities such as delayed growth. We argue that there remains a need to rethink the role played by proteases in bone physiology and pathology.

Biodiversity of CS–proteoglycan sulphation motifs: chemical messenger recognition modules with roles in information transfer, control of cellular behaviour and tissue morphogenesis

Chondroitin sulphate (CS) glycosaminoglycan chains on cell and extracellular matrix proteoglycans (PGs) can no longer be regarded as merely hydrodynamic space fillers. Overwhelming evidence over recent years indicates that sulphation motif sequences within the CS chain structure are a source of significant biological information to cells and their surrounding environment. CS sulphation motifs have been shown to interact with a wide variety of bioactive molecules, e.g. cytokines, growth factors, chemokines, morphogenetic proteins, enzymes and enzyme inhibitors, as well as structural components within the extracellular milieu. They are therefore capable of modulating a panoply of signalling pathways, thus controlling diverse cellular behaviours including proliferation, differentiation, migration and matrix synthesis. Consequently, through these motifs, CS PGs play significant roles in the maintenance of tissue homeostasis, morphogenesis, development, growth and disease. Here, we review (i) the biodiversity of CS PGs and their sulphation motif sequences and (ii) the current understanding of the signalling roles they play in regulating cellular behaviour during tissue development, growth, disease and repair.

Enzymatic inhibitory activity of Ficus deltoidea leaf extract on matrix metalloproteinase-2, 8 and 9

Dysregulation of matrix metalloproteinases (MMPs) activity is known in many pathological conditions with which most of the conditions are related to elevate MMPs activities. Ficus deltoidea (FD) is a plant known for its therapeutic properties. In order to evaluate the therapeutic potential of FD leaf extract, we study the enzymatic inhibition properties of FD leaf extract and its major bioactive compounds (vitexin and isovitexin) on a panel of MMPs (MMP-2, MMP-8 and MMP-9) using experimental and computational approaches. FD leaf extract and its major bioactive compounds showed pronounced inhibition activity towards the MMPs tested. Computational docking analysis revealed that vitexin and isovitexin bind to the active site of the three tested MMPs. We also evaluated the cytotoxicity and cell migration inhibition activity of FD leaf extract in the endothelial EA.hy 926 cell line. Conclusively, this study provided additional information on the potential of FD leaf extract for therapeutical application.

Synthetic 8-hydroxydeoxyguanosine inhibited metastasis of pancreatic cancer through concerted inhibitions of ERM and Rho-GTPase

8-hydroxydeoxyguanosine (8-OHdG) is generated consequent to oxidative stress, but its paradoxical anti-oxidative, anti-inflammatory, and anti-mutagenic effects via Rho-GTPase inhibition were noted in various models of inflammation and cancer. Metastasis occurs through cell detachment, epithelial-mesenchymal transition (EMT), and cell migration; during these processes, changes in cell morphology are initiated through Rho-GTPase-dependent actin cytoskeleton polymerization. In this study, we explored the anti-metastatic mechanisms of 8-OHdG in Panc-1 pancreatic cancer cells. 8-OHdG inhibits cell migration by inactivating ERM and Rho-GTPase proteins, and inhibiting focal adhesion kinase (FAK) and matrix metalloproteinases (MMPs). At 15min, 8-OHdG significantly inactivated ERM (p < 0.05) and led to a significant retardation of wound healing; siERM and H1152 (ROCK inhibitor) had similar effects (p < 0.05). However, FAK inhibitor 14, DPI (NOX inhibitor), and NAC (antioxidant) significantly delayed wound healing without inhibiting ERM or CD44 (p < 0.05). In the experiments on cell migration, siERM, siCD44, DPI, and 8-OHdG significantly inhibited MMPs. 8-OHdG significantly decreased DCF-DA activation in Panc-1 pancreatic cancer cells and down-regulated NOXs (nox-1, nox-2, and nox-3). Finally, all of these anti-migration actions of 8-OHdG resulted in significant inhibition of EMT, as evidenced by the up-regulation of ZO-1 and claudin-1 and down-regulation of vimentin. We found significant inhibition of lung metastasis of Panc-1 cells by 8-OHdG. In conclusion, exogenous 8-OHdG had potent anti-metastasis effects mediated by either ERM or Rho GTPase inhibition in metastasis-prone pancreatic cancer cells.

Selective small-molecule inhibitors as chemical tools to define the roles of matrix metalloproteinases in disease

The focus of this article is to highlight novel inhibitors and current examples where the use of selective small-molecule inhibitors has been critical in defining the roles of matrix metalloproteinases (MMPs) in disease. Selective small-molecule inhibitors are surgical chemical tools that can inhibit the targeted enzyme; they are the method of choice to ascertain the roles of MMPs and complement studies with knockout animals. This strategy can identify targets for therapeutic development as exemplified by the use of selective small-molecule MMP inhibitors in diabetic wound healing, spinal cord injury, stroke, traumatic brain injury, cancer metastasis, and viral infection. This article is part of a Special Issue entitled: Matrix Metalloproteinases edited by Rafael Fridman.

Astragaloside IV inhibits PMA-induced EPCR shedding through MAPKs and PKC pathway

Astragaloside IV (AS-IV), a main active substance isolated from Astragalus membranaceus Bunge, has been shown to have multiple pharmacological effects. Endothelial cell protein C receptor (EPCR) is a marker of inflammation, and is also a major member of protein C (PC) anti-coagulation system. EPCR can be cut off from the cell surface by tumor necrosis factor-α converting enzyme (TACE), which is controlled through mitogen-activated protein kinase (MAPK) and protein kinase C (PKC) pathways. To develop novel therapeutic drug for EPCR shedding, the effect of AS-IV was studied in phorbol-12-myristate 13-acetate (PMA)-induced human umbilical vein endothelial cells (HUVECs) and the potential molecular mechanism of AS-IV action was investigated. The results showed that AS-IV could significantly inhibit PMA-induced EPCR shedding. In further study, AS-IV suppressed the expression and activity of TACE. In addition, AS-IV could decrease the phosphorylation of MAPK such as janus kinase (JNK) and p38, and inhibit activation of PKC through the prevention of non-phosphorylation and phosphorylation of specific PKC isoforms in PMA-stimulated HUVECs. These findings indicate that AS-IV may be used as a natural medicine to treat EPCR-related systemic inflammation and cardiovascular diseases by targeting MAPK and PKC pathway.

Effect of activated protein C in second intention healing of equine distal limb wounds: a preliminary study

OBJECTIVE

To investigate the effect of activated protein C (APC) on second intention healing of distal limb wounds in horses.

METHODS

In this experimental study of eight Standardbred geldings, six full-thickness skin wounds (2 × 1.5 cm) were created on one metacarpus (biopsy limb) and five similar wounds were created on the contralateral metacarpus (photographed limb). Three wounds on the biopsy limb were treated topically with 190 µg APC on days 1, 3, 6 and 9, while the remaining three wounds were untreated (control). One treated and one control wound were biopsied on days 4, 7 and 11 for histopathology. Wounds on the photographed limb were treated with either 66% Manuka honey gel, a commercial antibiotic ointment (bacitracin-neomycin-polymixin B ointment; BNP) or petrolatum daily throughout healing, treated on days 1,3,6 and 9 with 190 µg APC or left untreated. These wounds were digitally photographed and the wound area measured on day 1, then weekly until day 49. Overall time to healing was recorded.

RESULTS

There was no effect of APC on wound size, the rate of healing or the overall time to heal. However, compared with control wounds, histological scoring demonstrated enhanced epithelialisation (day 4) and angiogenesis (day 11). Wound healing variables for wounds treated with APC, Manuka honey gel and control wounds were not different and the variables for wounds treated with BNP and petrolatum demonstrated delayed healing.

CONCLUSION

The improvements in histological scores in APC-treated wounds suggest further study into the effect of APC on second intention wound healing in horses is warranted.

Biophysiochemical properties of endothelial cells cultured on bio-inspired collagen films

Background

In this study, we investigated the effect of the extracellular matrix on endothelial dysfunction by careful observation of human umbilical vein endothelial cells (HUVECs) cultured on denatured collagen film.

Results

HUVECs on denatured collagen film showed relatively high surface roughness compared with normal HUVECs. The expression levels of MMP-1, MMP-2 and CD146 increased in the ECs on denatured collagen film. In addition, we examined the accumulation of fluorescent beads on HUVEC layers subjected to circulatory flow. The number of accumulated fluorescent beads increased on the disorganized HUVEC layers.

Conclusions

The proposed in vitro study using bio-inspired collagen films could potentially be used in the size- and ligand-based design of drugs to treat endothelial dysfunction caused by circulatory vascular diseases.

Matrix metalloproteinase 2 and membrane type 1 matrix metalloproteinase co-regulate axonal outgrowth of mouse retinal ganglion cells

Restoration of correct neural activity following central nervous system (CNS) damage requires the replacement of degenerated axons with newly outgrowing, functional axons. Unfortunately, spontaneous regeneration is largely lacking in the adult mammalian CNS. In order to establish successful regenerative therapies, an improved understanding of axonal outgrowth and the various molecules influencing it, is highly needed. Matrix metalloproteinases (MMPs) constitute a family of zinc-dependent proteases that were sporadically reported to influence axon outgrowth. Using an ex vivo retinal explant model, we were able to show that broad-spectrum MMP inhibition reduces axon outgrowth of mouse retinal ganglion cells (RGCs), implicating MMPs as beneficial factors in axonal regeneration. Additional studies, using more specific MMP inhibitors and MMP-deficient mice, disclosed that both MMP-2 and MT1-MMP, but not MMP-9, are involved in this process. Furthermore, administration of a novel antibody to MT1-MMP that selectively blocks pro-MMP-2 activation revealed a functional co-involvement of these proteinases in determining RGC axon outgrowth. Subsequent immunostainings showed expression of both MMP-2 and MT1-MMP in RGC axons and glial cells. Finally, results from combined inhibition of MMP-2 and β1-integrin were suggestive for a functional interaction between these molecules. Overall, our data indicate MMP-2 and MT1-MMP as promising axonal outgrowth-promoting molecules. Axonal regeneration in the central nervous system is lacking in adult mammals, thereby impeding recovery from injury to the nervous system. Matrix metalloproteinases (MMPs) constitute a family of zinc-dependent proteases that were sporadically reported to influence axon outgrowth. Inhibition of specific MMPs reduced neurite outgrowth from mouse retinal explants. Our data indicate MMP-2 and MT1-MMP as promising axonal outgrowth-promoting molecules and show a possible link between MMP-2 and β1-integrin in axon outgrowth.

Endothelial protein C receptor-associated invasiveness of rheumatoid synovial fibroblasts is likely driven by group V secretory phospholipase A2

INTRODUCTION

Rheumatoid synovial fibroblasts (RASFs) mediate joint inflammation and destruction in rheumatoid arthritis (RA). Endothelial protein C receptor (EPCR) is a specific receptor for the natural anticoagulant activated protein C (APC). It mediates the cytoprotective properties of APC and is expressed in rheumatoid synovial tissue. A recent report shows that group V secretory phospholipase A2 (sPLA₂V) prevents APC from binding to EPCR in endothelium and inhibits EPCR/APC function. The aim of this study was to investigate the expression and function of EPCR on RASFs.

METHODS

Human synovial fibroblasts (SFs) were isolated from RA or osteoarthritis (OA) synovial tissues and treated with control, EPCR, or sPLA₂V small interfering RNA (siRNA); recombinant human APC, tumor necrosis factor-alpha (TNF-α), or sPLA₂V. RASF viability and migration/invasion were measured by 3-[4,5-dimethylthiazol-2-yl]-2,5-diphenyl tetrazolium bromide (MTT) and collagen gel migration/invasion assays, respectively, and cartilage degradation by 1,9-dimethylmethylene blue (DMMB) assay in the presence of human OA articular cartilage explants. The expression or activation of cytokines, EPCR, cadherin-11, mitogen-activated protein (MAP) kinases, and nuclear factor-kappa-B (NF-κB) or both were detected by enzyme-linked immunosorbent assay, Western blotting, or immunostaining.

RESULTS

EPCR was expressed by both OASFs and RASFs but was markedly increased in RASFs. When EPCR was suppressed by siRNA or blocking antibody cell viability, cell invasion and cartilage degradation were reduced by more than 30%. Inflammatory mediators interleukin-1-beta (IL-1β), cadherin-11, and NF-κB were significantly reduced by EPCR suppression under control or TNF-α-stimulated conditions. The expression or activation (or both) of MAP kinases ERK, p38, and JNK were also markedly decreased in cells transfected with EPCR siRNA. Further analysis revealed that sPLA₂V co-localized with EPCR on RASFs. Suppression of sPLA₂V reduced cell viability and cartilage degradation and increased APC binding to RASFs. Conversely, recombinant sPLA₂V increased cartilage degradation, blocked APC binding to RASFs, and could not rescue the effects induced by EPCR suppression.

CONCLUSIONS

Our results demonstrate that EPCR is overexpressed by RASFs and mediates the aggressive behavior of RASFs. This function of EPCR is contrary to its cytoprotective role in other settings and is likely driven by sPLA₂V.

Activated protein C and its potential applications in prevention of islet β-cell damage and diabetes

Activated protein C (APC) is derived from its precursor, protein C (PC). Originally thought to be synthesized exclusively by the liver, recent reports have shown that PC is also produced by many other cells including pancreatic islet β cells. APC functions as a physiological anticoagulant with anti-inflammatory, anti-apoptotic, and barrier-stabilizing properties. APC exerts its protective effects via an intriguing mechanism requiring combinations of endothelial PC receptor, protease-activated receptors, epidermal growth factor receptor, Tie2 or CD11b, depending on cell types. Diabetes is a chronic condition resulted from the body's inability to produce and/or properly use insulin. The prevalence of diabetes has risen dramatically and has become one of the major causes of premature mortality and morbidity worldwide. Diabetes prevention is an ideal approach to reduce this burden. Type 1 and type 2 diabetes are the major forms of diabetes mellitus, and both are characterized by an autoimmune response, intraislet inflammation, β-cell apoptosis, and progressive β-cell loss. Protecting β-cell from damage is critical in both prevention and treatment of diabetes. Recent in vitro and animal studies show that APC's strong anti-inflammatory and anti-apoptotic properties are beneficial in preventing β-cell destruction and diabetes in the NOD mouse model of type 1 diabetes. Future preventive and therapeutic uses of APC in diabetes look very promising.

Matrix metalloproteinase-2 and -9 as promising benefactors in development, plasticity and repair of the nervous system

It has been 50 years since Gross and Lapiere discovered collagenolytic activity during tadpole tail metamorphosis, which was later on revealed as MMP-1, the founding member of the matrix metalloproteinases (MMPs). Currently, MMPs constitute a large group of endoproteases that are not only able to cleave all protein components of the extracellular matrix, but also to activate or inactivate many other signaling molecules, such as receptors, adhesion molecules and growth factors. Elevated MMP levels are associated with an increasing number of injuries and disorders, such as cancer, inflammation and auto-immune diseases. Yet, MMP upregulation has also been implicated in many physiological functions such as embryonic development, wound healing and angiogenesis and therefore, these proteinases are considered to be crucial mediators in many biological processes. Over the past decennia, MMP research has gained considerable attention in several pathologies, most prominently in the field of cancer metastasis, and more recent investigations also focus on the nervous system, with a striking emphasis on the gelatinases, MMP-2 and MMP-9. Unfortunately, the contribution of these gelatinases to neuropathological disorders, like multiple sclerosis and Alzheimer's disease, has overshadowed their potential as modulators of fundamental nervous system functions. Within this review, we wish to highlight the currently known or suggested actions of MMP-2 and MMP-9 in the developing and adult nervous system and their potential to improve repair or regeneration after nervous system injury.

Activated protein C inhibits pancreatic islet inflammation, stimulates T regulatory cells, and prevents diabetes in non-obese diabetic (NOD) mice

Activated protein C (aPC) is a natural anticoagulant with strong cyto-protective and anti-inflammatory properties. aPC inhibits pancreatic inflammation and preserves functional islets after intraportal transplantation in mice. Whether aPC prevents the onset or development of type 1 diabetes (T1D) is unknown. In this study, when human recombinant aPC was delivered intraperitoneally, twice weekly for 10 weeks (from week 6 to 15) to non-obese diabetic (NOD) mice, a model for T1D, the incidence of diabetes was reduced from 70% (saline control) to 7.6% by 26 weeks of age. Islets of aPC-treated mice exhibited markedly increased expression of insulin, aPC/protein C, endothelial protein C receptor, and matrix metalloproteinase (MMP)-2 when examined by immunostaining. The insulitis score in aPC-treated mice was 50% less than that in control mice. T regulatory cells (Tregs) in the spleen, pancreatic islets, and pancreatic lymph nodes were increased 37, 53, and 59%, respectively, in NOD mice following aPC treatment. These Tregs had potent suppressor function and, after adoptive transfer, delayed diabetes onset in NOD.severe combined immunodeficiency mice. The culture of NOD mouse spleen cells with aPC reduced the secretion of inflammatory cytokines interleukin (IL)-1β and interferon-γ but increased IL-2 and transforming growth factor-β1, two cytokines required for Treg differentiation. In summary, our results indicate that aPC prevents T1D in the NOD mouse. The aPC mechanism of action is complex, involving induction of Treg differentiation, inhibition of inflammation, and possibly direct cyto-protective effects on β cells.

Co-localization of Protein Z, Protein Z-Dependent protease inhibitor and coagulation factor X in human colon cancer tissue: implications for coagulation regulation on tumor cells

INTRODUCTION

Several hemostatic system components, including factor X (FX), contribute to cancer progression. The Protein Z (PZ)/protein Z-dependent protease inhibitor (ZPI) complex directly inhibits factor Xa proteolytic activity. The aim of this study was to determine the antigenic distribution of ZPI and PZ, in relation to FX, as well as indicators of blood coagulation activation (F1+2 and fibrin) in human colon cancer tissue.

MATERIALS & METHODS

Studies were performed on human colon cancer fragments. Immunohistochemical (IHC) ABC procedures and double staining method employed polyclonal antibodies against PZ, FX, F1+2 and monoclonal antibodies against ZPI and fibrin. In-situ hybridization (ISH) methods employed biotin-labeled 25-nucleotide single-stranded DNA probes directed to either FX, PZ or ZPI mRNAs.

RESULTS

Expression of FX, PZ and ZPI in association with colon cancer cells was observed by IHC. Moreover, the presence of both F1+2 and fibrin in association with colon cancer cells was found, which indicates that blood coagulation activation proceeds extravascularly at the tumor site. Furthermore, expression of FX and PZ was visualized in association with endothelial cells. In turn, colon cancer-associated macrophages were characterized by FX , PZ and ZPI presence. The double staining studies revealed strong FX/PZ, FX/ZPI, as well as PZ/ZPI co-localization on colon cancer cells. ISH studies revealed the presence of FX mRNA, PZ mRNA and ZPI mRNA in colon cancer cells indicating induced synthesis of these proteins.

CONCLUSIONS

The localization of PZ/ZPI and FX in colon cancer cells indicates that PZ/ZPI may contribute to anticoagulant events at the tumor site. Strong co-localization of PZ/ZPI and FX in cancer cells, and the presence of the mRNAs encoding the proteins, suggests their role in the tumor's biology. However, the presence of F1+2 and fibrin at the colon cancer site also suggests that the regulation of FXa by the PZ/ZPI complex at this site is incomplete.

Combination of activated protein C and topical negative pressure rapidly regenerates granulation tissue over exposed bone to heal recalcitrant orthopedic wounds

Chronic wounds arising from orthopedic surgery present a major clinical challenge. Osteomyelitis may develop from polymicrobial infection, which can be unresponsive to treatment and lead to amputation. Topical negative pressure (TNP) is an effective treatment in wound management and is now used worldwide. Activated protein C (APC) is an anticoagulant with cytoprotective and healing properties. The aim of this study was to determine whether combined treatment of TNP and APC was tolerated and was efficacious for treatment of difficult-to-treat wounds. Four patients who presented to Royal North Shore Hospital with wounds that were not responsive to conventional therapy were studied. All cases showed a marked reduction in wound size and depth within 1 week of starting treatment and progressively improved over time. There was a remarkable increase in the volume of granulation tissue. After treatment, wounds either completely closed or provided sufficient granulation tissue to allow split-thickness skin grafting. The treatment was well tolerated, and the patients were able to be managed on out-patient basis. Long-term follow-up suggested that this treatment prevented osteomyelitis. This innovative treatment is very promising and may significantly increase quality of care for patients with recalcitrant orthopedic wounds. A randomized, placebo-controlled double blind trial is required to further determine the efficacy of APC plus TNP.

Elevated plasma matrix metalloproteinases and their tissue inhibitors in patients with severe sepsis

PURPOSE

Matrix metalloproteinases (MMPs) are essential for tissue remodeling. Our objectives were to determine (1) the concentrations of MMPs and their tissue inhibitors (TIMPs) in plasma obtained from patients with severe sepsis, (2) to correlate changes in MMP and TIMP levels with disease severity, and (3) to investigate recombinant activated protein C (rAPC) actions on plasma MMP2, 9 activities from severe sepsis patients.

MATERIALS AND METHODS

Matrix metalloproteinase and TIMP levels were quantified in plasma from patients with severe sepsis using antibody microarrays and gelatin zymography.

RESULTS

Plasma MMPs (3, 7, 8, 9) and TIMPs (1, 2, 4) on microarray were increased in severe sepsis on intensive care unit (ICU) day 1, with more than 3-fold increases in MMP3, MMP7, MMP8, MMP9, and TIMP4. Latent forms of MMP2, 9 on zymography were increased in plasma from patients with severe sepsis, whereas only half of severe sepsis patients showed active MMP9. Elevated MMP7 and MMP9 on ICU days 1 and 3 negatively correlated with multiple organ dysfunctions. The temporal activity patterns of MMP2, 9 during 21 ICU days were not altered in patients treated with rAPC or by the addition of exogenous rAPC to plasma.

CONCLUSION

Most plasma MMPs and TIMPS were elevated in patients with severe sepsis, but only a limited subset of MMPs (7, 9) negatively correlated with disease severity. Recombinant activated protein C does not appear to directly alter MMP2, 9 activities.

Suppression of phorbol-12-myristate-13-acetate-induced tumor cell invasion by piperine via the inhibition of PKCα/ERK1/2-dependent matrix metalloproteinase-9 expression

Piperine is a major component of black pepper, Piper nigrum Linn, used widely in traditional medicine. Several previous studies reported that piperine possesses various beneficial biological activities including antioxidant, anti-tumor and anti-inflammation properties. In the present study, we investigated the inhibitory effects of piperine on tumor invasion and migration and the possible mechanisms involved using human fibrosarcoma HT-1080 cells. We found that piperine suppresses PMA-enhanced matrix metalloproteinase-9 (MMP-9) expression at the protein, mRNA, and transcriptional levels through the suppression of NF-κB and AP-1 activation without changing the level of tissue inhibitor of metalloproteinase (TIMP)-1. Piperine also inhibits PMA-enhanced membrane-type 1 MMP expression without changing the level of tissue inhibitor of metalloproteinase (TIMP)-1 and TIMP-2. Piperine inhibited PMA-induced NF-κB and c-Jun nuclear translocation, which are upstream of PMA-induced MMP-9 expression and invasion. Furthermore, piperine strongly repressed the PMA-induced phosphorylation of ERK, which are dependent on the PKCα pathway. In conclusion, we demonstrated that the anti-invasive effects of piperine may occur through inhibition of PKCα and ERK phosphorylation and reduction of NF-κB and AP-1 activation, leading to down-regulation of MMP-9 expression. Thus, piperine has potential as a potent anti-cancer drug in therapeutic strategies for fibrosarcoma metastasis.

Suppression of phorbol-12-myristate-13-acetate-induced tumor cell invasion by bergamottin via the inhibition of protein kinase Cdelta/p38 mitogen-activated protein kinase and JNK/nuclear factor-kappaB-dependent matrix metalloproteinase-9 expression

Matrix metalloproteinase (MMP) plays an important role in the invasion and metastasis of cancer cells. The inhibitory effects of bergamottin, a cytochrome P450 inhibitor from Citrus paradis (grapefruit), on tumor invasion and migration and the possible mechanisms involved in this inhibition were investigated in human fibrosarcoma HT-1080 cells. Bergamottin reduced phorbol-12-myristate-13-acetate (PMA)-induced activation of MMP-9 and MMP-2 and further inhibited cell invasion and migration. Bergamottin suppressed PMA-enhanced expression of MMP-9 protein, mRNA and transcription activity levels through suppression of nuclear factor-kappaB (NF-kappaB) activation without changing the tissue inhibitor of metalloproteinase 1 level. Bergamottin also reduced PMA-enhanced MMP-2 expression through suppression of membrane-type 1 MMP, but did not alter tissue inhibitor of metalloproteinase 2 levels. Bergamottin inhibited PMA-induced NF-kappaB nuclear translocation and IkappaBalpha degradation, which are upstream of PMA-induced MMP-9 expression and invasion. Furthermore, bergamottin strongly repressed the PMA-induced phosphorylation of p38 mitogen-activated protein kinase and c-Jun N-terminal kinase (JNK), which are dependent on the protein kinase C-delta pathway. In conclusion, we demonstrated that the anti-invasive effects of bergamottin might occur through inhibition of protein kinase C-delta, p38 mitogen-activated protein kinase, and JNK phosphorylation and reduction of NF-kappaB activation, leading to downregulation of MMP-9 expression. These results suggest that the suppression of MMP expression contributes, at least in part, to the antitumor activity of bergamottin.

Physiology and pathophysiology of matrix metalloproteases

Matrix metalloproteases (MMPs) comprise a family of enzymes that cleave protein substrates based on a conserved mechanism involving activation of an active site-bound water molecule by a Zn(2+) ion. Although the catalytic domain of MMPs is structurally highly similar, there are many differences with respect to substrate specificity, cellular and tissue localization, membrane binding and regulation that make this a very versatile family of enzymes with a multitude of physiological functions, many of which are still not fully understood. Essentially, all members of the MMP family have been linked to disease development, notably to cancer metastasis, chronic inflammation and the ensuing tissue damage as well as to neurological disorders. This has stimulated a flurry of studies into MMP inhibitors as therapeutic agents, as well as into measuring MMP levels as diagnostic or prognostic markers. As with most protein families, deciphering the function(s) of MMPs is difficult, as they can modify many proteins. Which of these reactions are physiologically or pathophysiologically relevant is often not clear, although studies on knockout animals, human genetic and epigenetic, as well as biochemical studies using natural or synthetic inhibitors have provided insight to a great extent. In this review, we will give an overview of 23 members of the human MMP family and describe functions, linkages to disease and structural and mechanistic features. MMPs can be grouped into soluble (including matrilysins) and membrane-anchored species. We adhere to the 'MMP nomenclature' and provide the reader with reference to the many, often diverse, names for this enzyme family in the introduction.

Endogenous protein C is essential for the functional integrity of human endothelial cells

Circulating protein C (PC) plays a vital role as an anti-coagulant and anti-inflammatory mediator. We show here that human endothelial cells produce PC that acts through novel mediators to enhance their own functional integrity. When endogenous PC or its receptor, endothelial protein C receptor (EPCR), was suppressed by small interfering (si) RNA, human umbilical cord endothelial cell (HUVEC) proliferation was decreased and apoptosis elevated. Interestingly, PC or EPCR siRNA significantly increased HUVEC permeability, which is likely via reduction of the angiopoietin (Ang)1/Ang2 ratio and inhibition of the peripheral localization of the tight junction protein, zona occludins-1. In addition, PC or EPCR siRNA inhibited type IV collagen and matrix metalloproteinase-2, providing the first evidence that PC contributes to vascular basement membrane formation. These newly described actions of endogenous PC act to stabilize endothelial cells and enhance barrier function, to potentially promote the functional integrity of blood vessels.

Expression of protein C (PC), protein S (PS) and thrombomodulin (TM) in human colorectal cancer

INTRODUCTION

Colorectal cancer (CRC) is often complicated by thromboembolic episodes. It has been recognized that blood coagulation proteins play a role in cancer progression. An important inhibitory mechanism is provided by the protein C (PC) system consisting of PC, protein S (PS) and thrombomodulin (TM). Recently, novel biological activities have been ascribed to the PC system that do not relate to their hemostatic functions, eg. in angiogenesis, apoptosis and inflammation.

OBJECTIVES

The purpose of the study was to elucidate the solid phase interactions between CRC tissue and components of the PC system that may contribute to tumor progression.

MATERIAL AND METHODS

CRC tissues were obtained at surgical resection during treatment of 66 patients. Immunohistochemical studies were performed using polyclonal antibodies against PC, PS and TM. A semiquantitative analysis of the protein expression was also performed.

RESULTS

Weak expression of PC was observed in cancer cells of two-thirds of the specimens examined, while in 3/66 cases there was no staining for PC in cancer cells. One fourth of CRCs exhibited strong expression of PC. The presence of PS was demonstrated in 64/66 cases of CRC. However, its expression was irregular in terms of intensity of staining and percentage of cancer cells exhibiting protein expression. Weak expression of TM was demonstrated in two thirds of the cases examined, while a strong TM staining was revealed in one third of colon cancers.

CONCLUSION

Heterogeneous expression of the PC system components in CRC tissue may point to their biological activity modulating tumor growth.

Suppression of PMA-induced tumor cell invasion by dihydroartemisinin via inhibition of PKCalpha/Raf/MAPKs and NF-kappaB/AP-1-dependent mechanisms

Dihydroartemisinin (DHA), a semi-synthetic derivative of artemisinin, has recently been shown to possess antitumor activity in various cancer cells. However, the effects of DHA in preventing the invasion of cancer cells have not been studied. In the present study, we investigated the inhibitory effects of DHA on tumor invasion and migration and the possible mechanisms involved using human fibrosarcoma HT-1080 cells. DHA reduced PMA-induced activation of MMP-9 and MMP-2 and further inhibited cell invasion and migration. DHA suppressed PMA-enhanced expression of MMP-9 protein, mRNA, and transcriptional activity through suppressing NF-kappaB and AP-1 activation without changing the level of tissue inhibitor of metalloproteinase (TIMP)-1. DHA also reduced PMA-enhanced MMP-2 expression by suppressing membrane-type 1 MMP (MT1-MMP), but did not alter TIMP-2 levels. DHA-inhibited PMA-induced NF-kappaB and c-Jun nuclear translocation, which are upstream of PMA-induced MMP-9 expression and invasion. Furthermore, DHA strongly repressed the PMA-induced phosphorylation of Raf/ERK and JNK, which are dependent on the PKCalpha pathway. In conclusion, we demonstrated that the anti-invasive effects of DHA may occur through inhibition of PKCalpha/Raf/ERK and JNK phosphorylation and reduction of NF-kappaB and AP-1 activation, leading to down-regulation of MMP-9 expression. The data presented show that DHA is an effective anti-metastatic agent that functions by down-regulating MMP-9 gene expression.

Activated protein C enhances cell motility of endothelial cells and MDA-MB-231 breast cancer cells by intracellular signal transduction

Activated protein C (APC), an anticoagulant serine protease, has been shown to have non-hemostatic functions related to inflammation, cell survival, and cell migration. In this study we investigate the mechanism by which APC promotes angiogenesis and breast cancer invasion using ex vivo and in vitro methods. When proteolytically active, APC promotes cell motility/invasion and tube formation of endothelial cells. Ex vivo aortic ring assays verify the role of APC in promoting angiogenesis, which was determined to be dependent on EGFR and MMP activation. Given the capacity of APC to promote angiogenesis and the importance of this process in cancer pathology, we investigated whether the mechanisms by which APC promotes angiogenesis can also promote motility and invasion in the MDA-MB-231 breast cancer cell line. Our results indicate that, extracellularly, APC engages EPCR, PAR-1, and EGFR in order to increase the invasiveness of MDA-MB-231 cells. APC activation of matrix metalloprotease (MMP) -2 and/or -9 is necessary but not sufficient to increase invasion, and APC does not utilize the endogenous plasminogen activation system to increase invasion. Intracellularly, APC activates ERK, Akt, and NFkappaB, but not the JNK pathway to promote MDA-MB-231 cell motility. Similar to the hemostatic protease thrombin, APC has the ability to enhance both endothelial cell motility/angiogenesis and breast cancer cell migration.

Matrix metalloproteinase 2-integrin alpha(v)beta3 binding is required for mesenchymal cell invasive activity but not epithelial locomotion: a computational time-lapse study

Cellular invasive behavior through three-dimensional collagen gels was analyzed using computational time-lapse imaging. A subpopulation of endocardial cells, derived from explanted quail cardiac cushions, undergoes an epithelial-to-mesenchymal transition and invades the substance of the collagen gels when placed in culture. In contrast, other endocardial cells remain epithelial and move over the gel surface. Here, we show that integrin alpha(v)beta3 and matrix metalloproteinase (MMP)2 are present and active in cushion mesenchymal tissue. More importantly, functional assays show that mesenchymal invasive behavior is dependent on MMP2 activity and integrin alpha(v)beta3 binding. Inhibitors of MMP enzymatic activity and molecules that prevent integrin alpha(v)beta3 binding to MMP2, via its hemopexin domain, result in significantly reduced cellular protrusive activity and invasive behavior. Computational analyses show diminished intensity and persistence time of motility in treated invasive mesenchymal cells, but no reduction in motility of the epithelial-like cells moving over the gel surface. Thus, quantitative time-lapse data show that mesenchymal cell invasive behavior, but not epithelial cell locomotion over the gel surface, is partially regulated by the MMP2-integrin interactions.

New therapeutic applications for the anticoagulant, activated protein C

BACKGROUND

Activated protein C (APC) is derived from its precursor, protein C (PC). Originally thought to be synthesised exclusively by the liver, recent reports have shown that PC is also produced by endothelial cells, smooth muscle cells, keratinocytes and some leukocytes.

OBJECTIVE

To provide an update on the emerging therapeutic effects of APC.

RESULTS/CONCLUSION

APC functions as an anticoagulant with cytoprotective, anti-inflammatory and antiapoptotic properties. In vitro and preclinical data have revealed that APC exerts its protective effects via an intriguing mechanism requiring endothelial protein C receptor and protease activated receptor-1. Approved as a therapeutic agent for severe sepsis, APC is emerging as a potential treatment for a number of autoimmune and inflammatory diseases including spinal cord injury, asthma, chronic wounds and possibly rheumatoid arthritis. The future therapeutic uses of APC look very promising.

Autocrine actions of matrix metalloproteinase (MMP)-2 counter the effects of MMP-9 to promote survival and prevent terminal differentiation of cultured human keratinocytes

Cultured human keratinocytes produce matrix metalloproteinase (MMP)-2 and MMP-9. In this study, using small interfering RNA (siRNA) for MMP-2 or MMP-9, we investigated the functions of these two gelatinases in the regulation of survival by measuring growth, differentiation, apoptosis, and migration of cultured keratinocytes. MMP-2 siRNA treatment significantly decreased keratinocyte growth and migration, and stimulated apoptosis fourfold. In addition, MMP-2 siRNA caused a 70% reduction in keratin-14 (K14) and a fourfold increase in K10. In contrast, MMP-9 siRNA treatment exerted opposite effects on cell growth, apoptosis, and K10 expression. MMP-2 appears to act through the ERK MAP kinase and caspase-3 signaling pathways as evidenced by the 53% reduction in the level of phosphorylated ERK1/2 and threefold increase in phosphorylated p38 and stronger staining for active caspase-3 in response to MMP-2 siRNA. Dual fluorescent staining revealed that almost all cultured cells stained positive for MMP-2, with only a few scattered cells being positive for MMP-9. There were considerably more BrdU-positive cells following MMP-9 siRNA treatment, indicating that MMP-9 inhibited proliferation. In conclusion, MMP-2 stimulates keratinocyte survival whereas MMP-9 promotes terminal differentiation.

Activated protein C mediates a healing phenotype in cultured tenocytes

Tendon injuries cause considerable morbidity in the general adult population. The tenocytes within the tendon have the full capacity to heal the tendon intrinsically. Activated protein C (APC) plays an important role in coagulation and inflammation and more recently has been shown to promote cutaneous wound healing. In this study we examined whether APC can induce a wound healing phenotype in tenocytes. Sheep tenocytes were treated with APC, endothelial protein C receptor (EPCR) blocking antibody (RCR252) and/or EPCR small interfering (si)RNA. Cell proliferation and migration were measured by crystal violet assay and a scratch wounding assay, respectively. The expression of EPCR, matrix metalloproteinase (MMP)-2, type I collagen and MAP kinase activity were detected by real time PCR, zymography, immunofluorescence, immunohistochemistry and Western blotting. APC stimulated proliferation, MMP-2 activity and type I collagen deposition in a dose-dependent manner and promoted migration of cultured tenocytes. APC dose-dependently stimulated phosphorylated (P)-ERK2 and inhibited P-p38. Interestingly, tenocytes expressed EPCR protein, which was up-regulated by APC. When tenocytes were pre-treated with RCR252 or EPCR siRNA the effect of APC on proliferation, MMP-2 and type 1 collagen synthesis and MAP kinases was blocked. APC promotes the growth, MMP-2 activity, type I collagen deposition and migration of tenocytes. Furthermore, EPCR is expressed by tenocytes and mediates the actions of APC, at least partly by signalling through selective MAP kinases. These data implicate APC as a potential healing agent for injured tendons.

Angiogenic transforming capacity of IgG purified from plasma of type 1 diabetic patients

We previously demonstrated that plasma of type 1 diabetic patients contains antibodies complexed irreversibly with Grp94 that also display proteolytic activity. In this work, we wanted to test whether antibodies obtained from diabetic plasma may convey an inflammatory risk on vascular cells. To this aim, IgG were purified on the Protein-G column from individual plasma of eight type 1 diabetic patients, and then tested on HUVECs to measure effects on cell growth and morphologic changes at different incubation times. The purified fractions of IgG contained a significant amount of Fab/(Fab)(2), both free and in big aggregates, and anti-Grp94 antibodies, mostly irreversibly linked with, but also free of Grp94. The purified fractions of both Fab/(Fab)(2) and whole IgG stimulated the proliferation and sustained the angiogenic differentiation of human umbilical vein endothelial cells (HUVECs) at sub-nanomolar concentrations. IgG from normal plasma neither stimulated the cell growth nor induced any differentiation of HUVECs. The maximum cell growth stimulation occurred at 6-9 hrs and associated with the strong activation of the ERK1/2 pathway, whereas angiogenic transformation was completed later when the ERK1/2 activation was silenced and cell growth stimulation significantly reduced. Neither proteolytic activity of MMP-9 nor VEGF were apparently involved in mediating the angiogenic differentiation of HUVECs that mostly correlated with an increased expression of HSP70 closely coupled with cell membrane-bound inactive species of MMP-9. Results indicate that effects displayed on HUVECs by antibodies purified from diabetic plasma are likely sustained by immune complexes with Grp94 that may thus predict an increased risk of angiogenic transformation in vivo.

Human C-reactive protein promotes oxidized low density lipoprotein uptake and matrix metalloproteinase-9 release in Wistar rats

C-reactive protein (CRP) is present in the atherosclerotic plaques and appears to promote atherogenesis. Intraplaque CRP colocalizes with oxidized low density lipoprotein (OxLDL) and macrophages in human atherosclerotic lesions. Matrix metalloproteinase-9 (MMP-9) has been implicated in plaque rupture. CRP promotes OxLDL uptake and MMP induction in vitro; however, these have not been investigated in vivo. We examined the effect of CRP on OxLDL uptake and MMP-9 production in vivo in Wistar rats. CRP significantly increased OxLDL uptake in the peritoneal and sterile pouch macrophages compared with human serum albumin (huSA). CRP also significantly increased intracellular cholesteryl ester accumulation compared with huSA. The increased uptake of OxLDL by CRP was inhibited by pretreatment with antibodies to CD32, CD64, CD36, and fucoidin, suggesting uptake by both scavenger receptors and Fc-gamma receptors. Furthermore, CRP treatment increased MMP-9 activity in macrophages compared with huSA, which was abrogated by inhibitors to p38 mitogen-activated protein kinase, extracellular signal-regulated kinase (ERK), and nuclear factor (NF)-kappaB but not Jun N-terminal kinase (JNK) before human CRP treatment. Because OxLDL uptake by macrophages contributes to foam cell formation and MMP release contributes to plaque instability, this study provides novel in vivo evidence for the role of CRP in atherosclerosis.

Activated protein C--an anticoagulant that does more than stop clots

Activated protein C (APC) is a glycoprotein derived from its precursor, protein C and formed by the cleavage of an activation peptide by thrombin bound to thrombomodulin. Originally thought to be synthesized exclusively by the liver, recent reports have shown that protein C is synthesized by endothelial cells, keratinocytes and some hematopoietic cells. APC functions as a physiological anticoagulant with cytoprotective, anti-inflammatory and anti-apoptotic properties. In vitro and preclinical data have revealed that APC exerts its protective effects via an intriguing mechanism requiring endothelial protein C receptor and the thrombin receptor, protease-activated receptor-1. Remarkably, even though APC cleaves this receptor in an identical fashion to thrombin, it exerts opposing effects. Recently approved as a therapeutic agent for severe sepsis, APC is now emerging as a potential treatment for a number of autoimmune and inflammatory diseases including lung disorders, spinal cord injury and chronic wounds. The future pharmacologic use of APC holds remarkable promise.

Differential regulation of matrix metalloproteinase 2 and matrix metalloproteinase 9 by activated protein C: relevance to inflammation in rheumatoid arthritis

OBJECTIVE

To investigate the in vitro effect of activated protein C (APC), a natural anticoagulant and novel antiinflammatory agent, on the regulation of the gelatinases matrix metalloproteinase 2 (MMP-2) and MMP-9.

METHODS

Synovial fibroblasts and peripheral blood monocytes isolated from patients with rheumatoid arthritis (RA) or osteoarthritis (OA) and Mono Mac6 cells were used in this study. After treatment, cells and culture supernatants were collected for zymography, enzyme-linked immunosorbent assay, reverse transcription-polymerase chain reaction, and Western blot analysis.

RESULTS

Fibroblasts and monocytes from RA patients produced substantially more MMP-9 than did those from OA patients; however, there was no difference in MMP-2 production. The addition of recombinant APC markedly reduced MMP-9 at the gene and protein levels. In contrast, APC up-regulated and activated MMP-2. Using a blocking antibody to the endothelial protein C receptor (EPCR), we showed that the inhibition of MMP-9 by APC was EPCR-dependent. Furthermore, APC directly suppressed the production of tumor necrosis factor (TNF) and the activation of NF-kappaB and MAP kinase p38, and inhibitors of NF-kappaB or p38 reduced the production of MMP-9, suggesting that APC inhibits MMP-9 by blocking TNF, NF-kappaB, and p38. Thus, APC acts on MMP-9 by binding to EPCRs on the cell surface and, subsequently, inhibiting the intracellular activation of the proinflammatory signaling molecules NF-kappaB and p38.

CONCLUSION

APC appears to be the first physiologic agent to inhibit the production of proinflammatory MMP-9, yet increase antiinflammatory MMP-2 activity. Our results provide the initial evidence that APC may be beneficial in the prevention of inflammation and joint destruction in RA.

The effect of fibrinolytic enzyme FIIa from Agkistrodon acutus venom on disseminated intravascular coagulation in rabbits

A novel fibrinolytic enzyme, FII(a), was isolated from Agkistrodon acutus venom, which can degrade fibrin/fibrinogen and dissolve thrombus without activating plasminogen or influencing the activities of tissue plasminogen activator (t-PA) and plasminogen activator inhibitor type-1 (PAI-1). In this study, we evaluated the effect of FII(a) on lipopolysaccharide (LPS)-induced experimental disseminated intravascular coagulation (DIC) in rabbits, through the continuous infusion of 100-microg/kg/h LPS for a period of 6 h. Seven groups were established: LPS control, FII(a) (0.1, 0.3, and 0.6 mg/kg/h, respectively), heparin control (100 IU/kg/h), heparin + FII(a) (heparin 100 IU/kg/h associated with FII(a) 0.3 mg/kg/h), and a saline control group. A continuous injection of LPS induced a gradual impairment in hemostatic parameters, kidney fibrin deposition, and a high mortality rate. The intravenous administration of FII(a) improved the concentration of fibrinogen, the activities of protein C, plasminogen, t-PA, antithrombin III (ATIII), and PAI-1. Kidney fibrin deposition and the mortality also decreased. In the in vitro experiments, FII(a) can degrade fibrin/fibrinogen and high-dose FII(a) enhanced the activity of protein C. These findings suggest that the effects of FII(a) on LPS-induced DIC were from fibrinogen degradation and enhanced protein C activity. The simultaneous administration of FII(a) and heparin further improved all the hemostatic parameters, including decreased kidney fibrin deposition, and none of the rabbits died within 24 h, which indicates that the effects were mediated by degradation of fibrin/fibrinogen together with thrombin inhibition. We conclude that FII(a) may be useful in the treatment of DIC.

Opposite effects of high glucose on MMP-2 and TIMP-2 in human endothelial cells

Diabetes mellitus (DM) is a major risk factor for atherosclerosis and causes multiple cardiovascular complications. Although high glucose can induce matrix metalloproteinases (MMPs), its inhibitors and cell apoptosis, little is known about the roles of MMPs in regulating cell apoptosis in response to high glucose. To address this issue, we elucidated the relationship between MMPs, its inhibitors and cell apoptosis in human umbilical vein endothelial cells (HUVECs). HUVECs were treated with medium containing 5.5 mM or 33 mM of glucose in the presence or the absence of ascorbic acid and MMP inhibitors (GM6001 and endogenous tissue inhibitors of MMPs, TIMP-1, and TIMP-2). For detection of cell apoptosis, the cell death detection ELISA assay was used. The results revealed that high glucose-induced apoptosis could be suppressed by ascorbic acid, GM6001 and TIMP-2, but not by TIMP-1. The activities of MMP-2, MMP-9 and its inhibitors, TIMP-1, TIMP-2 after high glucose treatment, were also detected by ELISA method. We found that the activated form of MMP-2, but not MMP-9, was increased, while the level of TIMP-2, but not TIMP-1, was decreased. In Western blot and RT-PCR analysis, the expression of TIMP-2, but not TIMP-1, after high glucose treatment was downregulated, whereas the levels of MMP-2 and -9 proteins and mRNA were not changed. The present study indicated that oxidative stress induced by high glucose might be involved in the opposite effects on MMP-2 activation and TIMP-2 downregulation. This reactive oxygen species (ROS)-dependent MMP-2 activation in turn mediates high glucose-induced cell apoptosis in HUVECs.

Protein C is an autocrine growth factor for human skin keratinocytes

The protein C (PC) pathway plays an important role in coagulation and inflammation. Many components of the PC pathway have been identified in epidermal keratinocytes, including endothelial protein C receptor (EPCR), which is the specific receptor for PC/activated PC (APC), but the core member of this pathway, PC, and its function in keratinocytes has not been defined. In this study, we reveal that PC is strongly expressed by human keratinocytes at both gene and protein levels. When endogenous PC was blocked by siRNA the proliferation of keratinocytes was significantly decreased. This inhibitory effect was restored by the addition of recombinant APC. PC siRNA treatment also increased cell apoptosis by 3-fold and inhibited cell migration by more than 20%. When keratinocytes were pretreated with RCR252, an EPCR-blocking antibody, or PD153035, an epidermal growth factor receptor (EGFR) inhibitor, cell proliferation was hindered by more than 30%. These inhibitors also completely abolished recombinant APC (10 mug/ml)-stimulated proliferation. Blocking PC expression or inhibiting its binding to EPCR/EGFR decreased the phosphorylation of ERK1/2 but increased p38 activation. Furthermore, inhibition of ERK decreased cell proliferation by approximately 30% and completely abolished the stimulatory effect of APC on proliferation. Taken together, these results indicate that keratinocyte-derived PC promotes cell survival, growth, and migration in an autocrine manner via EPCR, EGFR, and activation of ERK1/2. Our results highlight a novel role for the PC pathway in normal skin physiology and wound healing.

Activated protein C promotes breast cancer cell migration through interactions with EPCR and PAR-1

Activated protein C (APC) is a serine protease that regulates thrombin (IIa) production through inactivation of blood coagulation factors Va and VIIIa. APC also has non-hemostatic functions related to inflammation, proliferation, and apoptosis through various mechanisms. Using two breast cancer cell lines, MDA-MB-231 and MDA-MB-435, we investigated the role of APC in cell chemotaxis and invasion. Treatment of cells with increasing APC concentrations (1-50 microg/ml) increased invasion and chemotaxis in a concentration-dependent manner. Only the active form of APC increased invasion and chemotaxis of the MDA-MB-231 cells when compared to 3 inactive APC derivatives. Using a modified "checkerboard" analysis, APC was shown to only affect migration when plated with the cells; therefore, APC is not a chemoattractant. Blocking antibodies to endothelial protein C receptor (EPCR) and protease-activated receptor-1 (PAR-1) attenuated the effects of APC on chemotaxis in the MDA-MB-231 cells. Finally, treatment of the MDA-MB-231 cells with the proliferation inhibitor, Na butyrate, showed that APC did not increase migration by increasing cell number. Therefore, APC increases invasion and chemotaxis of cells by binding to the cell surface and activating specific signaling pathways through EPCR and PAR-1.

The cytoprotective protein C pathway

Protein C is best known for its mild deficiency associated with venous thrombosis risk and severe deficiency associated with neonatal purpura fulminans. Activated protein C (APC) anticoagulant activity involves proteolytic inactivation of factors Va and VIIIa, and APC resistance is often caused by factor V Leiden. Less known is the clinical success of APC in reducing mortality in severe sepsis patients (PROWESS trial) that gave impetus to new directions for basic and preclinical research on APC. This review summarizes insights gleaned from recent in vitro and in vivo studies of the direct cytoprotective effects of APC that include beneficial alterations in gene expression profiles, anti-inflammatory actions, antiapoptotic activities, and stabilization of endothelial barriers. APC's cytoprotection requires its receptor, endothelial cell protein C receptor, and protease-activated receptor-1. Because of its pleiotropic activities, APC has potential roles in the treatment of complex disorders, including sepsis, thrombosis, and ischemic stroke. Although much about molecular mechanisms for APC's effects on cells remains unclear, it is clear that APC's structural features mediating anticoagulant actions and related bleeding risks are distinct from those mediating cytoprotective actions, suggesting the possibility of developing APC variants with an improved profile for the ratio of cytoprotective to anticoagulant actions.

Quantitation and localization of matrix metalloproteinases and their inhibitors in human carotid endarterectomy tissues

BACKGROUND

Matrix metalloproteinases (MMPs) and their inhibitors (TIMPs) play a central role in arterial wall remodeling, affecting stability of fibrous caps covering atherosclerotic plaques. The objective of this study was to determine the spatial distribution of TIMP mass and MMP mass and activity of carotid endarterectomy (CEA) tissues and relate it to the distribution of atherosclerotic lesions.

METHODS AND RESULTS

Fresh CEA tissues were imaged by multicontrast MRI to generate 3D reconstructions. Tissue segments were cut transversely from the common, bifurcation, internal, and external regions. Segments were subjected to total protein extractions and analyzed by ELISA for MMP-2 and -9 and TIMP-1 and -2 mass and by zymography for gelatinase activity. Segments at or near the bifurcation with highly calcified lesions contained higher MMP levels and activity than segments distant from the bifurcation; highly fibrotic or necrotic plaque contained lower MMP levels and activity and higher TIMP levels. Fatty streak, fibroatheroma with hemorrhage and calcification, and fully occluded lesions were enriched in MMP-2, MMP-9, and TIMP-1 and TIMP-2, respectively.

CONCLUSIONS

The spatial distribution of MMPs and TIMPs in carotid atherosclerotic lesions is highly heterogeneous, reflecting lesion location, size, and composition. This study provides the first semi-quantitative maps of differential distribution of MMPs and TIMPs over atherosclerotic plaques.

Targeting matrix metalloproteases to improve cutaneous wound healing

Wound repair is a physiological event in which tissue injury initiates a repair process leading to restoration of structure and function of the tissue. Cutaneous wound repair can be divided into a series of overlapping phases including formation of fibrin clot, inflammatory response, granulation tissue formation incorporating re-epithelialisation and angiogenesis and finally, matrix formation and remodelling. Matrix metalloproteases (MMPs) are a family of neutral proteases that play a vital role throughout the entire wound healing process. They regulate inflammation, degrade the extracellular matrix (ECM) to facilitate the migration of cells and remodel the new ECM. However, excessive MMP activity contributes to the development of chronic wounds. Selective control of MMP activity may prove to be a valuable therapeutic approach to promote healing of chronic ulcers. Recent evidence indicates that the anticoagulant, activated protein C may be useful in the treatment of non-healing wounds by preventing excessive protease activity through inhibition of inflammation and selectively increasing MMP-2 activity to enhance angiogenesis and re-epithelialisation.

Endothelial protein C receptor and protease-activated receptor-1 mediate induction of a wound-healing phenotype in human keratinocytes by activated protein C

Activated protein C (APC) is a natural anticoagulant and inhibitor of inflammation that can stimulate keratinocyte wound repair in vitro and promote wound healing in vivo. The signaling mechanisms, however, are unknown and a keratinocyte receptor for APC has not been identified. Here, we show that cultured human keratinocytes from neonatal foreskins express the endothelial protein C receptor (EPCR). EPCR was also strongly expressed by lower epidermal layers of neonatal foreskin as determined by immunohistochemistry. In cultured keratinocytes, EPCR expression was upregulated by the addition of APC and inhibited by tumor necrosis factor-alpha. Addition of APC stimulated cell proliferation, production of matrix metalloproteinase-2, activation of ERK and p38 kinase signaling pathways, and expression of protease-activated receptor (PAR)-1. A monoclonal antibody, RCR252, which blocks APC binding to EPCR, or a blocking antibody to PAR-1, abolished APC's effects on keratinocytes. In summary, this study demonstrates that EPCR, a major receptor of protein C pathway, is expressed by human keratinocytes, and facilitates APC's function on keratinocytes via activation of PAR-1 pathway. Our findings highlight a possible new role for the protein C pathway in skin physiology and help elucidate the mechanisms of action by which APC promotes wound healing.

Modulation of angiogenic processes in cultured endothelial cells by low density lipoproteins subfractions from patients with familial hypercholesterolemia

OBJECTIVE

Electronegative low density lipoprotein (LDL) subfractions are cytotoxic to endothelial cells. To continue our study of homozygotic familial hypercholesterolemic (FH)-LDL, we report the effects of FH-LDL subfractions (FH-L1 to FH-L5) on the angiogenic processes in cultured endothelial cells.

METHODS AND RESULTS

Subconfluent bovine aortic endothelial cells (BAEC) were treated with LDL subfractions (20 microg/ml), and the effects on angiogenic functions, including cell proliferation, migration, apoptosis, tube formation, secretion of matrix metalloproteinases (MMPs), and vascular endothelial growth factor (VEGF) were determined. The electronegative FH-L4 and FH-L5 inhibited cell proliferation while the other FH-LDL subfractions and LDL from normocholesterolemic subjects (N-LDL) had negligible effects. Like Cu2+ ox-LDL, FH-L5 strongly inhibited endothelial cell viability and FH-L4 had a milder effects. Similarly, FH-L4 and FH-L5 but not the other subfractions retarded cell migration, induced cell apoptosis, and perturbed tube formation by BAEC in matrigel. FH-L5 inhibited secretion of MMP-2 and MMP-9 by BAEC without affecting their endogenous levels. In contrast, FH-L5 increased the VEGF expression in endothelial cells.

CONCLUSIONS

Our results show for the first time that FH-L5, a circulating LDL subfraction from hypercholesterolemic patients, modulates various angiogenic processes, thereby dysregulating endothelial function in a way that may be atherogenic.