Effects of Enzamin, a Microbial Product, on Alterations of Intestinal Microbiota Induced by a High-Fat Diet

In the human intestinal tract, there are more than 100 trillion microorganisms classified into at least 1000 different species. The intestinal microbiota contributes to the regulation of systemic physiologic functions and the maintenance of homeostasis of the host. It has been reported that the alteration of the intestinal microbiota is involved in metabolic syndromes, including type II diabetes and dyslipidemia, inflammatory bowel disease, allergic disease, and cancer growth. It has been reported that a microbial product from Paenibacillus polymyxa AK, which was named Enzamin, ameliorated adipose inflammation with impaired adipocytokine expression and insulin resistance in db/db mice. In order to investigate the effect of Enzamin on the intestinal microbiota and inflammation induced by obesity, mice were fed with a high-fat diet and 1% Enzamin for 4 weeks. Enzamin improved the Firmicutes-to-Bacteroidetes ratio and altered the intestinal microbiota in mice fed the high-fat diet. In addition, Enzamin suppressed the decreased expression of claudin-4 and the increased serum LPS level in mice fed with the high-fat diet. Modulating the intestinal microbiota with Enzamin may cause a decrease in serum LPS level. Based on these results, Enzamin may improve inflammation and metabolic disorders by regulating the intestinal microbiota in obese mice.

Protective Effects of Eicosapentaenoic Acid on the Glomerular Endothelium via Inhibition of EndMT in Diabetes

Diabetes-induced endothelial pathologies are hypothesized to lead to the progression of diabetic kidney disease (DKD). The endothelial to mesenchymal transition (EndMT) possibly induces fibrosis, leading to glomerulosclerosis in the kidney. Furthermore, this could lead to albuminuria in diabetic nephropathy due to glomerular endothelial dysfunction. Eicosapentaenoic acid (EPA), purified from fish oil, decreases inflammatory cytokine levels in glomerulonephritis. Here, we aimed at finding whether ethyl eicosapentaenoate (EPA-E) exerts renal protective effects via EndMT inhibition. To find out whether EPA inhibits EndMT in vitro, the changes in CD31 expression were studied in cultured mouse endothelial cells. The addition of the conditioned medium from the adipocyte culture significantly decreased the protein levels of CD31, while the addition of EPA-E partially reversed this inhibition. Further, EndMT inhibition by EPA-E treatment might occur via the inhibition of the protein kinase Cβ (PKCβ)/transforming growth factor-β (TGF-β)/plasminogen activator inhibitor-1 (PAI-1) signaling and not via microRNAs. Streptozotocin-induced diabetic mice fed a high-fat diet (60% from fat) exhibited mesangial expansion and albuminuria. Induction of EPA-E ameliorated the mesangial expansion and decreased albuminuria without affecting blood pressure, triglyceride and free fatty acid levels, and intraperitoneal glucose. These findings suggest that EPA-E exerts renal protective effects on endothelial cells, by normalizing EndMT followed by the PKCβ/TGF-β/PAI-1 signaling. Thus, EPA-E has the potential for imparting renal protection by regulating EndMT in DKD.

Effects of Coriandrum sativum on Migration and Invasion Abilities of Cancer Cells

Coriandrum sativum (coriander) is an annual herb in the Apiaceae family. Its leaves and seeds are used for cooking. Coriander has several beneficial functions such as anti-inflammatory, analgesic and anti-cancer effects. Although anti-carcinogenic potential of coriander has been known well, the effects of coriander on cancer metastasis have not yet been fully elucidated. In the present study, the effects of coriander on migration and invasion were investigated in vitro and in vivo by using human hepatocellular carcinoma cell line (HepG2) and mouse melanoma cell line (B16F10). The migration and invasion abilities of cancer cells had been evaluated by trans-well double chamber and these abilities were significantly impaired by treatment of cancer cells with coriander extract whose concentration did not affect proliferation. The treatment of cancer cells with coriander extract significantly reduced both matrix metalloproteinase 2 (MMP-2) and urokinase-type plasminogen activator (u-PA) activities, which were involved in cell migration and invasion, in their conditioned media. Furthermore, coriander extract suppressed the phosphorylation of Erk 1 or IkB in B16F10 cells, and inhibited the expression of MMP-2 or u-PA mRNA. After injection of B16F10 cells into the tail vein of C57BL/6J mice, the number of metastatic regions in lungs were counted. Mice fed with diet containing coriander possessed a smaller number of metastatic regions than those fed with control diet. It was suggested that coriander extract might have the abilities to suppress cancer cell migration and invasion, indicating that coriander provides the improvement of cancer prognosis.

Linagliptin affects IRS1/Akt signaling and prevents high glucose-induced apoptosis in podocytes

Diabetes-induced podocyte apoptosis is considered to play a critical role in the pathogenesis of diabetic kidney disease (DKD). We proposed that hyperglycaemia can induce podocyte apoptosis by inhibiting the action of podocyte survival factors, thus inactivating the cellular effects of insulin signalling. In this study, we aimed to determine the effects of linagliptin on high glucose-induced podocyte apoptosis. Linagliptin reduced the increase in DNA fragmentation as well as the increase in TUNEL-positive cells in podocytes induced by high-glucose condition. Furthermore, linagliptin improved insulin-induced phosphorylation of insulin receptor substrate 1 (IRS1) and Akt, which was inhibited in high-glucose conditions. Adenoviral vector-mediated IRS1 overexpression in podocytes partially normalised DNA fragmentation in high-glucose conditions, while downregulation of IRS1 expression using small interfering RNA increased DNA fragmentation even in low-glucose conditions. Because reactive oxygen species inhibit glomerular insulin signalling in diabetes and Kelch-like ECH-associated protein 1 (Keap1)/nuclear factor erythroid 2-related factor 2 (Nrf2) pathway is one of the most important intrinsic antioxidative systems, we evaluated whether linagliptin increased Nrf2 in podocytes. High-glucose condition and linagliptin addition increased Nrf2 levels compared to low-glucose conditions. In summary, linagliptin offers protection against DKD by enhancing IRS1/Akt insulin signalling in podocytes and partially via the Keap1/Nrf2 pathway. Our findings suggest that linagliptin may induce protective effects in patients with DKD, and increasing IRS1 levels could be a potential therapeutic target in DKD.

Antithrombotic Effect of Oral Administration of Mozuku (Cladosiphon okamuranus, Brown Seaweed) Extract in Rat

Dysfunction of vascular endothelial cells causes the risk of thrombosis. Aim of this study is to evaluate the antithrombotic effect of Okinawa mozuku (brown seaweed, Cladosiphon okamuranus) extract by using cultured vascular endothelial cells and rat carotid arterial thrombosis model induced by ferric chloride (FeCl3). The cell line (TKM-33) established from human umbilical vein endothelial cells were cultured with or without Okinawa mozuku extract. After incubation for 24 h, the conditioned medium was collected to evaluate urokinase-type plasminogen activator (u-PA) activity. Next, rats were fed with water or water containing 5% of Okinawa mozuku extract for 8 wk. After 8 wk of treatments, the rats were provided for the carotid arterial thrombosis model, and fibrinolytic factor and coagulation factor in blood were measured. Okinawa mozuku extract significantly augmented u-PA activity in the conditioned medium. The decrease of carotid artery blood flow induced by 40% FeCl3 injury in rats fed with Okinawa mozuku extract was less than that in control rats. Thus, oral administration of Okinawa mozuku extract prevented thrombus formation in this model. Oral administration of Okinawa mozuku extract significantly increased u-PA activity in euglobulin fraction, compared with control group. On the other hand, platelet aggregation activity, activated partial thromboplastin time, and active PAI-1 level in plasma exhibited no significant differences between control and Okinawa mozuku groups. These results indicate that oral administration of Okinawa mozuku enhances fibrinolytic activity in plasma and prevents thrombus formation which is induced by injury of vascular endothelial cells.

Effect of Heat Shock on the Expression of Urokinase-Type Plasminogen Activator Receptor in Human Umbilical Vein Endothelial Cells

We investigated the effect of heat shock on the fibrinolytic potential of human umbilical vein endothelial cells (HUVECs) in culture. When cultured at 43° C, the mRNA for heat shock protein 70 (HSP70) was dramatically induced within 120 min with a maximal induction of more than 90-fold compared with that in HUVECs cultured at 37° C. The level of urokinase-type plasminogen activator (u-PA) receptor (u-PAR) mRNA increased up to 2.2-fold in response to heat shock, which was associated with the increased u-PA binding and cell-surface u-PA activity determined by adding exogenous u-PA to acid-treated HUVECs. The increased u-PAR mRNA returned to normal level when HUVECs were further incubated at 37° C for 180 min, and this decline was not affected in the presence of actinomycin D. Though the secreted antigens for tissue-type plasminogen activator (t-PA) and type 1 plasminogen activator inhibitor (PAI-1) in the conditioned medium (CM) of HUVECs were simultaneously increased at 43° C during this period, the increase in the levels of t-PA (about 26.6-fold at 120 min) was greater than that of PAI-1 (1.8-fold at 120 min). The fibrinolytic activity of CM obtained from HUVECs at 43° C was significantly enhanced up to 3-fold, indicating that heat shock induced hyperfibrinolytic states in HUVECs. The secretion of u-PA into CM was also enhanced by heat shock. These results suggested that human endothelial cells respond to hyperthermia by inducing HSP70 followed by hyperfibrinolytic states with the enhanced expression of u-PAR as well as that of t-PA and u-PA.

Expression and Characterization of Clustered Charge-to-Alanine Mutants of Low Mr Single-Chain Urokinase-Type Plasminogen Activator

In an effort to modify the fibrinolytic and/or pharmacokinetic properties of recombinant low M r single-chain urokinase-type plasminogen activator (rscu-PA-32k), mutants were prepared by site-directed mutagenesis of clusters of charged amino acids with the highest solvent accessibility. The following mutants of rscu-PA-32k were prepared: LUK-2 (Lys 212, Glu 213 and Asp 214 to Ala), LUK-3 (Lys 243 and Asp 244 to Ala), LUK-4 (Arg 262, Lys 264, Glu 265 and Arg 267 to Ala), LUK-5 (Lys 300, Glu 301 and Asp 305 to Ala) and LUK-6 (Arg 400, Lys 404, Glu 405 and Glu 406 to Ala).

The rscu-PA 32k moictic3 were expressed in High Five Ttichoplasiani cells, and purified to humugciicily from the conditioned cell culture medium, with recoveries of 0.8 to 3.7 mg/1. The specific fibrinolytic activities (220,000 to 300,000 IU/mg), the rates of plasminogen activation by the single-chain moieties and the rates of conversion In lwo chain moieties by plasmin were comparable for mutant and wild-type rscu PA 32k moieties, with the exception of LUK-5 which was virtually inactive. Equi-effective lysis (50% in 2 h) of 60 pi 125I-fibrin labeled plasma clots submerged in 0.5 ml normal human plasma was obtained with 0.7 to 0.8 μg/ml of wild-type or mutant rscu-PA-3?.k, except with LUK-5 (no significant lysis with 16 pg/ml). Following bolus injection in hamsters, all rscu-PA-32k moieties had a comparably rapid plasma clearance (1.3 to 2.7 ml/min), as a result of a short initial half-life (1.4 to 2.5 min). In hamsters with pulmonary embolism, continuous intravenous infusion over 60 min at a dose of 1 mg/kg, resulted in 53 to 72% clot lysis with the mutants, but only 23% with LUK-5, as compared to 36% for wild-type rscu-PA-32k.

These data indicate that clustered charge-to-alanine mutants of rscu-PA-32k, designed to eliminate charged regions with the highest solvent accessibility, do not have significantly improved functional, fibrinolytic or pharmacokinetic properties.

Molecular Conversions of Recombinant Staphylokinase During Plasminogen Activation in Purified Systems and in Human Plasma

Recombinant staphylokinase (STAR) is produced as a 136 amino acid protein with NH2-terminal sequence Ser-Ser-Ser (mature STAR, HMW-STAR), which may be converted to lower molecular weight forms (LMW-STAR) by removal of the first six residues (yielding STAR-Δ6 with NH2-terminal Gly-Lys-Tyr-) or the first ten residues (yielding STAR-Δ10 with NH2-terminal Lys-Gly-Asp-). In the present study the occurrence and effects of these conversions during plasminogen activation by HMW-STAR were studied in purified systems and in human plasma.

In stoichiometric mixtures of HMW-STAR and native human plasminogen (Glu-plasminogen), rapid and quantitative conversion of HMW-STAR to LMW-STAR occurred, concomitant with exposure of the active site in the plasmin-STAR complex. NH2-terminal amino acid sequence analysis revealed the sequence Lys-Gly-Asp- in addition to the known sequences of the Lys-plasmin chains, identifying STAR-Δ10 as the derivative generated from HMW-STAR. In mixtures of catalytic amount of HMW-STAR and human plasminogen, plasmin generation occurred progressively, following an initial lag phase, during which HMW-STAR was converted to LMW-STAR. Plasmin-mediated conversion of HMW-STAR to LMW-STAR obeyed Michaelis-Menten kinetics with K m = 3.6 μM and k 2 = 0.38 s−1. The specific clot lysis activities of HMW-STAR (122,000 ± 8,000 units/mg) and LMW-STAR (129,000 ± 8,000 units/mg) were indistinguishable.

In an in vitro system consisting of a 60 μl plasma clot submerged in 250 μl plasma, 80% clot lysis within 1 h was obtained with 70 nM HMW-STAR. This was associated with fibrinogen depletion and conversion of 20% of the HMW-STAR to LMW-STAR. Addition of 100 nM HMW-STAR to human plasma in the absence of a clot did not induce significant fibrinogen breakdown (≥ 90% residual fibrinogen after 2 h), and was not associated with significant coversion to LMW-STAR (≤10% within 2 h). With 400 nM HMW-STAR, fibrinogen depletion in plasma occurred within 1 h, and 80% conversion to LMW-STAR was observed. Thus, at fibrinolytically active concentrations which do not cause fibrinogen breakdown, no significant conversion of HMW-STAR to LMW-STAR occurs in human plasma in the absence of a clot.

These findings indicate that the conversion of HMW-STAR to LMW-STAR may occur in association with clot lysis, but is not required to induce it.

Recombinant Variants of Tissue-Type Plasminogen Activator Containing Amino Acid Substitutions in the Finger Domain

Tissue-type plasminogen activator (t-PA) is a fibrin-specific agent which has been used to treat acute myocardial infarction. In an attempt to clarify the determinants for its rapid clearance in vivo and high affinity for fibrin clots, we produced five variants containing amino acid substitutions in the finger domain, at amino acid residues 7–9, 10–14, 15–19, 28–33, and 37–42. All the variants had a prolonged half-life and a decreased affinity for fibrin of various degrees. The 37–42 variant demonstrated about a 6-fold longer half-life with a lower affinity for fibrin. Human plasma clot lysis assay estimated the fibrinolytic activity of the 37–42 variant to be 1.4-fold less effective than that of the wild-type rt-PA. In a rabbit jugular vein clot lysis model, doses of 1.0 and 0.15 mg/kg were required for about 70% lysis in the wild-type and 37–42 variant, respectively. Fibrinogen was degraded only when the wild-type rt-PA was administered at a dose of 1.0 mg/kg. These findings suggest that the 37–42 variant can be employed at a lower dosage and that it is a more fibrin-specific thrombolytic agent than the wild-type rt-PA.

Obesity-associated glomerular inflammation increases albuminuria without renal histological changes

Obesity is one of risk factors for chronic kidney disease (CKD), but the precise mechanism involved is unclear. This study characterizes the effect of obesity-induced glomerular inflammation, oxidative stress, and albuminuria in obese rats. Glomerular samples were collected from fatty (ZF) and lean (ZL) Zucker rats. After 2 months of feeding, body weight and albuminuria were significantly increased in ZF rats when compared to ZL rats. Expression of the inflammatory markers TNF-α and CCR2 was significantly increased in the glomeruli of ZF rats. However, expression of IL-6 mRNA was not increased. Analysis of renal pathology showed no glomerular expansion. As inflammatory and oxidative stress markers are associated with NF-κB, we evaluated whether NF-κB activation was increased in the glomeruli of mice on a high-fat diet. Immunohistochemistry showed increased NF-κB activation in the glomeruli when transgenic mice overexpressing an NF-κB-dependent enhanced green fluorescent protein were fed with a high-fat diet. These results suggest that obesity of only 2 months duration can cause albuminuria, due to increased inflammation or oxidative stress, but may not be long enough to develop renal pathological changes.

Plasmin Generation Plays different Roles in the Formation and Removal of Arterial and Venous Thrombus in Mice

The role of plasminogen (Plg) and α2-antiplasmin (α2-AP) in vascular thrombolysis in vivo was investigated in mice deficient in plasminogen (Plg−/−) or α2-AP (α2-AP−/−) or their wild type (PAI-1+/+, α2AP+/+). A thrombus was induced in the murine carotid artery or the internal jugular vein by endothelial injury. Blood flow was continuously monitored for 90 min and for 6 h 30 min after the initiation of endothelial injury. The times to occlusion by the developing thrombus in the carotid artery and the jugular vein of wild type mice were 12 ± 1.8 and 7.2 ± 1.9 min, respectively. The arterial thrombus formation in α2AP−/− mice was indistinguishable from the one in wild type mice, whereas the time to occlusion in Plg−/− was significantly shortened to 5.9 ± 1.7 min. Vascular patency after spontaneous reperfusion was markedly improved in α2-AP−/− mice. On the contrary, arterial patency in Plg−/− mice was aggravated. In venous thrombus formation, the time to occlusion in α2-AP−/− mice was significantly prolonged (27.1 ± 5.2 min), whereas in Plg−/− it was slightly shortened to 6.5 ± 2.5 min. Vascular patency after spontaneous reperfusion was also improved in α2-AP−/− mice, but not in Plg−/− mice. Histological observations using SEM indicated that fibrin nets were firmly fixed on the injured area in Plg−/− mice, but not in α2-AP−/− mice. The tail bleeding time was not different in any type of mice. However, re-bleeding time using a template bleeding device was significantly prolonged in α2-AP−/− as compared with that of wild type mice. In conclusion, lack of plasminogen markedly reduces the antithrombotic activities in vivo, whereas α2-AP plays a more important role in the formation and removal of venous thrombus in mice. Consequently, the inhibition of α2-AP could be a useful tool for the therapy of venous thrombosis and the prevention of re-thrombus formation.

Suppression of argatroban-induced endogenous thrombolysis by PKSI-527, and antibodies to TPA and UPA, evaluated in a rat arterial thrombolysis model

We have previously confirmed, using a rat mesenteric arteriole thrombolysis model, that thrombin inhibition induces endogenous thrombolysis in vivo. In addition, we have shown that thrombin-activatable fibrinolysis inhibitor (TAFI) plays a role in the down regulation of endogenous thrombolysis. However, the mechanism of endogenous thrombolysis or spontaneous plasmin generation in vivo remains unclear.

It has been shown in an in vitro system that plasma kallikrein activates pro-urokinase (pro uPA) and/or plasminogen, resulting in plasmin generation. These findings suggest that spontaneous fibrinolysis might be mediated by tPA and plasma kallikrein-dependent uPA. The aim of the present study was to examine whether these mechanisms play a dominant role in endogenous thrombolysis in vivo, using our rat mesenteric arterial thrombolysis model.

Argatroban infusion enhanced endogenous thrombolysis. PKSI-527, anti uPA and anti tPA IgGs suppressed argatroban-induced thrombolysis. Also, the antibody IgG preparations suppressed endogenous thrombolysis in the absence of argatroban. In the presence of PKSI-527, anti tPA IgG was more effective than anti uPA IgG in suppressing argatroban-induced thrombolysis. The results suggested that both tPA and plasma kallikrein-mediated uPA activation and tPA release contribute to endogenous fibrinolytic or thrombolytic mechanisms.

Differential Role of Components of the Fibrinolytic System in the Formation and Removal of Thrombus Induced by Endothelial Injury

The role of fibrinolytic system components in thrombus formation and removal in vivo was investigated in groups of six mice deficient in urokinase-type plasminogen activator (u-PA), tissue-type plasminogen activator (t-PA), or plasminogen activator inhibitor-1 (PAI-1) (u-PA-/-, t-PA-/- or PAI-1-/-, respectively) or of their wild type controls (u-PA+/+, t-PA+/+ or PAI-1+/+). Thrombus was induced in the murine carotid artery by endothelial injury using the photochemical reaction between rose bengal and green light (540 nm). Blood flow was continuously monitored for 90 min on day 0 and for 20 min on days 1, 2 and 3. The times to occlusion after the initiation of endothelial injury in u-PA+/+, t-PA+/+ or PAI-1+/+ mice were 9.4 ± 1.3, 9.8 ± 1.1 or 9.7 ± 1.6 min, respectively. u-PA-/- and t-PA-/- mice were indistinguishable from controls, whereas that of PAI-1-/- mice were significantly prolonged (18.4 ± 3.7 min). Occlusion persisted for the initial 90 min observation period in 10 of 18 wild type mice and was followed by cyclic reflow and reocclusion in the remaining 8 mice. At day 1, persistent occlusion was observed in 1 wild type mouse, 8 mice had cyclic reflow and reocclusion and 9 mice had persistent reflow. At day 2, all injured arteries had persistent reflow. Persistent occlusion for 90 min on day 0 was observed in 3 u-PA-/-, in all t-PA-/- mice at day 1 and in 2 of the t-PA-/-mice at day 2 (p <0.01 versus wild type mice). Persistent patency was observed in all PAI-1-/- mice at day 1 and in 5 of the 6 u-PA-/- mice at day 2 (both p <0.05 versus wild type mice). In conclusion, t-PA increases the rate of clot lysis after endothelial injury, PAI-1 reduces the time to occlusion and delays clot lysis, whereas u-PA has little effect on thrombus formation and spontaneous lysis.

Lack of tPA Significantly Affects Antithrombotic Therapy by a GPIIb/IIIa Antagonist, but not by a Thrombin Inhibitor in Mice

The interaction of fibrinolytic components with platelets or coagulation factors after endothelial injury, was investigated in mouse deficient in tissue type plasminogen activator (tPA –/–), or urokinase (uPA –/–) and in their wild type control (tPA +/+, uPA +/+). A thrombus was induced in the murine carotid artery using the photochemical reaction. Blood flow was continuously monitored and the time needed before the vessel became completely obstructed was within 11 min in all types of mice. When GR144053, a platelet glycoprotein IIb/IIIa antagonist, or argatroban, a thrombin inhibitor, was applied, the time required to occlusion was prolonged in a dose-dependent manner in all types of mice. However, when GR144053 was injected in tPA –/– mice, the most significant changes were observed: that is the estimated ED50 was 14.8 times higher than the one in tPA +/+ mice. On the other hand, when argatroban was injected in tPA –/– mice, the estimated ED50 was not changed. Platelet aggregation, haemostasis tests and bleeding times were not significantly different among the different types of mice. In conclusion, the antithrombotic effect of platelet inhibition by a GPIIb/IIIa antagonist, is severely affected by the absence or presence of tPA-production. Thus, the lack of tPA significantly reduces the antithrombotic efficacy.

Function of Tissue-type Plasminogen Activator Releaser on Vascular Endothelial Cells and Thrombolysis In Vivo

The effect of monosodium[2-(6-hydroxynaphthalen-2-yl)-6-methylpyrimidin-4-yloxy]acetate dihydrate (JTV-926) on fibrinolysis was investigated in vitro and in vivo. JTV-926 released tissue-type plasminogen activator (t-PA) from human vascular endothelial cells in a dose-dependent manner. The thrombolytic effect of JTV-926 was studied using three animal thrombosis models; a photo-irradiation-induced mouse carotid artery thrombosis model, a photo-irradiation-induced rat femoral artery thrombosis model and a thrombin-induced rat venous thrombosis model. In the mouse thrombosis model, t-PA deficient mice (t-PA−/−mice) and their wild-type (t-PA+/+) were used. JTV-926 was injected as a bolus 30 min after the interruption of blood flow by an occlusion thrombi. Blood flow was continuously monitored for 180 min after intravenous administration of JTV-926 (1 mg/kg). Although the recanalization rate of the occluded artery was 37.5% in t-PA +/+ mice with the vehicle control, it increased to 75% in t-PA+/+ mice after JTV-926 administration. However, when JTV-926 was administrated in t-PA−/−mice, vascular recanalization was not observed in any arteries. In the photo-irradiation-induced rat femoral artery thrombosis model, intra-duodenal administration of JTV-926 induced thrombolysis. Moreover, in the thrombin-induced rat venous thrombosis model, the dose-dependent thrombolysis was also observed by oral administration of JTV-926. It was suggested that JTV-926 revealed a sufficient thrombolytic effect through the absorption from the intestine. Thus, a newly synthesized compound, JTV-926 induced t-PA release from vascular endothelial cells and effective thrombolysis in vivo.

Transcriptional Regulation of Urokinase-type Plasminogen Activator Receptor by Cyclic AMP in PL-21 Human Myeloid Leukemia Cells: Comparison with the Regulation by Phorbol Myristate Acetate

We investigated the effect of dibutyryl cyclic AMP (Bt2-cAMP) on urokinase-type plasminogen activator receptor (uPAR) expression in human PL-21 myeloid leukemia cells and compared it with the effect of phorbol myristate acetate (PMA). Flow cytometric analysis clearly demonstrated that Bt2-cAMP and PMA both induced the cell surface expression of uPAR. Northern analysis and nuclear run-on assay revealed that cAMP and PMA activated the uPAR gene transcription and both additively increased the uPAR mRNA level. However, actinomycin-D decay experiment showed that PMA, but not cAMP, prolonged the uPAR mRNA half-life. Furthermore, inhibition of the ongoing protein synthesis with cycloheximide abrogated completely the PMA-induced uPAR mRNA accumulation but only partially the induction by PMA plus cAMP, whereas the induction by cAMP alone was rather amplified, indicating that the de novo protein synthesis is necessary in the induction by PMA but not in the induction by cAMP and that the cAMP pathway may be dominant in uPAR gene expression in the PL-21 cells as compared to the PMA pathway. These results suggest that cAMP induces the uPAR expression exclusively through activating the gene transcription in which a preexisting transcriptional factor may be involved, whereas PMA transcriptionally and post-transcriptionally regulates the uPAR gene expression.

Effect of staphylokinase-derived nonadecapeptide on the activation of plasminogen

Staphylokinase (SAK) expresses plasminogen activator (PA) activity by forming a complex with plasmin. The interaction between the plasmin-SAK complex and plasminogen was investigated using synthesized peptides, which were constructed according to the amino acid sequence of the SAK molecule.A synthetic nonadecapeptide (SAK22–40) corresponding to Glu22-Leu40 by the SAK molecule enhanced the activation of Glu-plasminogen by the plasmin-SAK complex.Analysis of IAsys resonant mirror biosensor showed that SAK22–40 bound to Glu-plasminogen.This binding was completely inhibited by IgG against the B-chain in the plasminogen molecule. But, this binding was not inhibited by IgG against lysine-binding sites (LBS) of the A-chain in the plasminogen molecule. The substitution of Lys35 with Ala in SAK22–40 did not enhance the activation of Glu-plasminogen by the plasmin-SAK complex. When SAK22–40 was administrated in a mouse thrombosis model, earlier recanalization was observed than in mice with vehicle administration. Thus, a newly synthesized peptide, SAK22–40 enhanced Glu-plasminogen activation and induced effective thrombolysis.

Role of GPx4 in human vascular endothelial cells, and the compensatory activity of brown rice on GPx4 ablation condition

Oxidative stress is implicated in the pathologies of vascular endothelial cells. However, the importance of specific antioxidant enzymes in vascular endothelial cells is not fully understood. The purpose of this study was to elucidate the importance of Glutathione peroxidase 4 (GPx4), and the involvement of ferroptosis on cell death induced by GPx4 loss in human vascular endothelial cells. In addition, we examined the compensatory activity of brown rice on GPx4 ablation condition. Human umbilical vein endothelial cells were transfected with GPx4 or scramble control siRNA. GPx4 knockdown caused the increase in the levels of lipid oxidation, and induced cytotoxicity. On the other hand, α-tocopherol (vitamin E) and extract of brown rice, ameliorated lipid peroxidation, cytotoxicity, and delay of proliferation induced by GPx4 knockdown. Furthermore, ferrostatin-1, inhibitor of ferroptosis, also prevented cytotoxicity and delay of proliferation. In conclusion, our data demonstrated that GPx4 is an essential antioxidant enzyme for protecting lipid peroxidation, and is a regulator of ferroptosis in vascular endothelial cells. Furthermore, vitamin E rich food, such as brown rice, can compensate for GPx4 loss by protecting cells against lipid peroxidation.

α2AP mediated myofibroblast formation and the development of renal fibrosis in unilateral ureteral obstruction

Renal fibrosis is the final common pathway of a wide variety of chronic kidney diseases. Myofibroblast formation via the differentiation of from tissue-resident fibroblasts and bone marrow-derived mesenchymal stem cells (MSCs), and epithelial-to-mesenchymal transition (EMT) is known to play a pivotal role in the development of renal fibrosis. However, the detailed mechanisms underlying this disorder remain unclear. We herein investigated the role of alpha 2-antiplasmin (α2AP) in myofibroblast formation and the development of renal fibrosis. We observed the development of renal fibrosis using unilateral ureteral obstruction (UUO). α2AP had accumulated in the UUO-induced obstructed kidneys and α2AP deficiency attenuated UUO-induced renal fibrosis in mice. The degree of myofibroblast formation in the obstructed kidneys of α2AP(-/-) mice was less than that in α2AP(+/+) mice. In vitro, α2AP induced myofibroblast formation in renal tubular epithelial cells (RTECs), renal fibrosblasts, and bone marrow-derived mesenchymal stem cells (MSCs). α2AP also induced the production of TGF-β, which is known to be a key regulator of myofibroblast formation and fibrosis. α2AP-induced the TGF-β production was significantly reduced by SP600125, c-Jun N-terminal kinase (JNK) specific inhibitor. Our findings suggest that α2AP induces myofibroblast formation in the obstructed kidneys, and mediates the development of renal fibrosis.

Enhanced pre-operative thrombolytic status is associated with the incidence of deep venous thrombosis in patients undergoing total knee arthroplasty

Background

Deep venous thrombosis (DVT), which is often associated with pulmonary embolism (PE), is a serious complication after total knee arthroplasty (TKA). In the present study, we examined the overall thrombotic and thrombolytic status using Global Thrombosis Test (GTT) in non-anticoagulated blood of patients undergoing TKA to develop the predictable marker for the incidence of DVT.

Methods

DVT was diagnosed using doppler ultrasonography a day after the surgery in 31 patients with osteoarthritis (n = 24), rheumatoid arthritis (n = 6) and ankylosing spondylitis (n = 1) by the well-trained operator. We measured overall thrombotic and thrombolytic status using GTT and other biomarkers, which is associated with blood coagulation and fibrinolysis, before and immediately after the surgery.

Results

Newly-generated DVT during the operation was detected in 11 of 31 patients (35.4%) 1 day after TKA. There were no differences in markers of coagulation (PT and APTT), platelet activity (platelet aggregation-induced by ADP and collagen) and fibrinolysis (FDP and D-dimer) between non-DVT and DVT group both before and after the surgery. Both Pre- and Post-operative GTT-occlusion times (OT), an index of platelet reactivity, were tended to be shorter, but not significant, in DVT group compared with non-DVT group. Pre-operative GTT-lysis time (LT), an index of thrombolytic activity, was significantly shorter in DVT group compared with non-DVT group, while there were no differences in post-operative value of this index between DVT group and non-DVT group, suggesting overall thrombolytic activity was enhanced in DVT group before surgery.

Conclusions

Our data suggest that enhancement of pre-operative thrombolytic activity assessed by GTT may be a predictable marker for the incidence of DVT after TKA.

Involvement of α2-antiplasmin in dendritic growth of hippocampal neurons

The α2-Antiplasmin (α2AP) protein is known as a principal physiological inhibitor of plasmin, but we previously demonstrated that it acts as a regulatory factor for cellular functions independent of plasmin. α2AP is highly expressed in the hippocampus, suggesting a potential role for α2AP in hippocampal neuronal functions. However, the role for α2AP was unclear. This study is the first to investigate the involvement of α2AP in the dendritic growth of hippocampal neurons. The expression of microtubule-associated protein 2, which contributes to neurite initiation and neuronal growth, was lower in the neurons from α2AP⁻/⁻ mice than in the neurons from α2AP⁺/⁺ mice. Exogenous treatment with α2AP enhanced the microtubule-associated protein 2 expression, dendritic growth and filopodia formation in the neurons. This study also elucidated the mechanism underlying the α2AP-induced dendritic growth. Aprotinin, another plasmin inhibitor, had little effect on the dendritic growth of neurons, and α2AP induced its expression in the neurons from plaminogen⁻/⁻ mice. The activation of p38 MAPK was involved in the α2AP-induced dendritic growth. Therefore, our findings suggest that α2AP induces dendritic growth in hippocampal neurons through p38 MAPK activation, independent of plasmin, providing new insights into the role of α2AP in the CNS.

Urokinase-type plasminogen activator and plasminogen mediate activation of macrophage phagocytosis during liver repair in vivo

Urokinase-type plasminogen activator (u-PA) and plasminogen play a primary role in liver repair through the accumulation of macrophages and alteration of their phenotype. However, it is still unclear whether u-PA and plasminogen mediate the activation of macrophage phagocytosis during liver repair. Herein, we investigated the morphological changes in macrophages that accumulated at the edge of damaged tissue induced by a photochemical reaction or hepatic ischaemia-reperfusion in mice with u-PA ( u-PA-/- ) or plasminogen ( Plg-/- ) gene deficiency by using transmission electron and fluorescence microscopy. In wild-type mice, the macrophages aligned at the edge of the damaged tissue and extended a large number of long pseudopodia. These macrophages clearly engulfed cellular debris and showed well-developed organelles, including lysosome-like vacuoles, nuclei, and Golgi complexes. In wild-type mice, the distribution of the Golgi complex in these macrophages was biased towards the direction of the damaged tissue, indicating the extension of their pseudopodia in this direction. Conversely, in u-PA-/- and Plg-/- mice, the macrophages located at the edge of the damaged tissue had few pseudopodia and less developed organelles. The Golgi complex was randomly distributed in these macrophages in u-PA-/- mice. Furthermore, interferon γ and IL-4 were expressed at a low level at the border region of the damaged tissue in u-PA-/- mice. Our data provide novel evidence that u-PA and plasminogen are essential for the phagocytosis of cellular debris by macrophages during liver repair. Furthermore, u-PA plays a critical role in the induction of macrophage polarity by affecting the microenvironment at the edge of damaged tissue.

Profibrinolytic effect of Enzamin, an extract of metabolic products from Bacillus subtilis AK and Lactobacillus

Fibrinolytic system impairment contributes to the development of thrombotic disease such as cardiovascular disease and stroke. Therefore, an agent that increases fibrinolytic activity may be useful for the prevention of these diseases. In this study, to explore novel profibrinolytic agents, we examined the profibrinolytic effect of Enzamin, an extract of metabolic products from Bacillus subtilis AK and Lactobacillus in vitro and in vivo. Enzamin directly enhanced plasmin activity generated by tissue-type plasminogen activator (t-PA) by twofold but not by urokinase-type plasminogen activator (u-PA) in vitro, which was measured employing both the chromogenic substrate H-D: -Val-Leu-Lys-pNA (S-2251) and fibrin plate. Enzamin also increased plasmin activity generated by t-PA in the cell lysate and culture medium of endothelial cells, measured by fibrin zymography. Furthermore, the oral administration of a 1% concentration of Enzamin increased plasmin activity generated by t-PA by 1.7-fold but not by u-PA in the euglobulin fraction of mouse plasma. In conclusion, Enzamin has a unique ability to enhance the fibrinolytic activity through an increase in endogenous plasmin activity generated by t-PA released from endothelial cells, and may be a beneficial supplement for the prevention of thrombotic episodes.

A synthetic peptide derived from staphylokinase enhances plasminogen activation by tissue-type plasminogen activator

BACKGROUND

A synthetic nonadecapeptide (SP; GPYLMVNVTGVDGKGNELL) previously enhanced the activation of plasminogen by the SAK/plasmin complex.

OBJECTIVES

To identify the binding site for SP on plasminogen and elucidate the effects of SP on plasminogen activation by the tissue-type plasminogen activator (t-PA).

METHODS

The effects of SP on plasminogen activation were estimated using a chromogenic substrate and from the cleavage of plasmin on SDS-PAGE under reduced conditions. The binding to SP of various peptides derived from the amino acid sequence of plasminogen was analyzed with an IAsys biosensor. The SP-mediated structural change to plasminogen was analyzed by circular dichroism (CD) spectroscopy. The thrombolytic effects of SP were examined using a mouse model of thrombosis.

RESULTS

SP enhanced the activation of plasminogen by t-PA. The catalytic efficiency (k(cat)/K(m)) of Glu-plasminogen activation by t-PA was 11.4-fold higher in the presence than absence of SP. The binding of SP to plasminogen was greatly inhibited by a synthetic peptide, FEKDKYILQGVTSWGLG, located close to the C-terminal of the plasminogen B region. Near-ultraviolet CD spectra of the complex between SP and Glu-plasminogen significantly differed from those of Glu-plasminogen. When SP was administered in a mouse model of thrombosis, early recanalization was observed in a dose-dependent manner. However, SP did not cause recanalization in t-PA gene-deficient mice.

CONCLUSIONS

SP bound to the B region and promoted the activation of plasminogen by t-PA, and then induced effective thrombolysis.

Urokinase-type plasminogen activator contributes to heterogeneity of macrophages at the border of damaged site during liver repair in mice

Urokinase-type plasminogen activator (u-PA) plays an important role in tissue remodelling through the activation of plasminogen in the liver, but its mechanisms are less well known. Here, we investigated the involvement of u-PA in the accumulation and phenotypic heterogeneity of macrophages at the damaged site during liver repair. After induction of liver injury by photochemical reaction in mice, the subsequent pathological responses and expression of phenotypic markers in activated macrophages were analysed histologically. Fibrinolytic activity at the damaged site was also examined by fibrin zymography. In wild-type mice, the extent of damage decreased gradually until day 14 and was associated with an accumulation of macrophages at the border of the damaged site. In addition, the macrophages that accumulated near the damaged tissue expressed CD206, a marker of highly phagocytic macrophages, on day 7. Further, macrophages that were adjacent to CD206-positive cells expressed inducible nitric oxide synthase (iNOS), a pro-inflammatory marker. u-PA activity increased at the damaged site on days 4 and 7, which distributed primarily at the border region. In contrast, in u-PA-deficient mice, the decrease in damage size and the accumulation of macrophages were impaired. Further, neither CD206 nor iNOS was expressed in the macrophages that accumulated at the border region in u-PA-deficient mice. Mice deficient for the gene encoding either u-PA receptor (u-PAR) or tissue-type plasminogen activator experienced normal recovery during liver repair. These data indicate that u-PA mediates the accumulation of macrophages and their phenotypic heterogeneity at the border of damaged sites through u-PAR-independent mechanisms.

A case of Helicobacter pylori infection complicated with gastric cancer, gastric mucosa-associated lymphoid tissue lymphoma, and idiopathic thrombocytopenic purpura successfully treated with laparoscopy-assisted total gastrectomy and splenectomy

Helicobacter pylori infection plays a key role in the pathogenesis of H. pylori-associated diseases, including gastroduodenal and non-gastroduodenal diseases. A 71-year-old man was evaluated for a positive fecal occult blood test by upper gastrointestinal endoscopy, which revealed H. pylori infection, two adenocarcinomas and two gastric mucosa-associated lymphoid tissue lymphomas. Hematological examination revealed low platelet-count, elevated platelet-associated immunoglobulin G and anti-H. pylori immunoglobulin G antibodies. We diagnosed H. pylori infection complicated by simultaneous occurrence of gastric cancer, gastric mucosa-associated lymphoid tissue lymphoma, and idiopathic thrombocytopenic purpura. These diseases were successfully treated with laparoscopy-assisted total gastrectomy and splenectomy, and there was no evidence of recurrence for about 2 years. This is the first reported case of H. pylori infection complicated by these three diseases and cured with laparoscopic surgery.

Plasminogen/plasmin modulates bone metabolism by regulating the osteoblast and osteoclast function

The contribution of plasminogen (Plg)/plasmin, which have claimed to be the main fibrinolytic regulators in the bone metabolism, remains unclear. This study evaluated how the absence of Plg affects the function of osteoblast (OB) and osteoclast (OC). There was a larger population of pre-OCs in bone marrow-derived cells from the Plg(-/-) mice than the population of that from the WT mice. In addition, the absence of Plg suppressed the expression of osteoprotegerin in OBs. Moreover, an exogenous plasmin clearly induced the osteoprotegerin expression in Plg(-/-) OBs. The osteoclastogenesis of RAW264.7 mouse monocyte/macrophage lineage cells in co-culture with OBs from the Plg(-/-) mice was significantly accelerated in comparison with that in co-culture with OBs from the WT mice. Intriguingly, the accelerated OC differentiation of RAW264.7 cells co-cultured with Plg(-/-) OBs was clearly suppressed by the treatment of an exogenous plasmin. Consequently, Plg(-/-) mice display decreased bone mineral density. These findings could eventually lead to the development of new clinical therapies for bone disease caused by a disorder of the fibrinolytic system.

Urokinase-type plasminogen activator receptor is associated with the development of adipose tissue

Urokinase-type plasminogen activator receptor (uPAR) plays a role in cellular responses which include cellular adhesion, differentiation, proliferation and migration. The aim of this study was to clarify the role of uPAR on the development of adipose tissue. To clarify the role of uPAR on adipogenesis, we examined the effect of uPAR overexpression and uPAR deficiency on the adipocyte differentiation. Adipocyte differentiation was induced by incubation of 3T3-L1 cells with differentiation media containing insulin, dexamethasone, and 1-methyl-3-isobutyl-xanthin. uPAR overexpression by transfection of uPAR expression vector induced adipocyte differentiation. In addition, we examined the difference in adipocyte differentiation of mesenchymal stem cells from wild-type mice and uPAR knockout (uPAR-/-) mice. The uPAR deficiency attenuated differentiation media-induced adipocyte differentiation. Moreover, we found that the inhibition of phosphatidylinositol 3-kinase (PI3K) pathway attenuated uPAR overexpression-induced adipocyte differentiation, and uPAR overexpression induced the activation of Akt. We also found that an increase of the adipose tissue mass in uPAR-/- mice was less than that observed in wild-type mice. The present results suggest that uPAR plays a pivotal role in the development of adipose tissue through PI3K/Akt pathway.

Tissue plasminogen activator and plasminogen are critical for osmotic homeostasis by regulating vasopressin secretion

Systemic osmotic homeostasis is regulated mainly by neuroendocrine system of arginine-vasopressin (AVP) in mammalians. In the present study, we demonstrated that the immunoreactivity of tissue plasminogen activator (tPA) was observed specifically at neurosecretory granules of AVP-positive magnocellular terminals and that of plasminogen was seen at astrocytes in the neurohypophysis (NH). Both tPA and plasminogen knockout (KO) mice revealed higher plasma osmolarity upon water deprivation, a chronic osmotic stimulation, as compared with their wild-type (WT) animals, indicating abnormal osmotic control in these KO mice. tPA KO mice but not plasminogen ones revealed lower ability in secreting AVP into the blood circulation upon an acute osmotic stimulation. Both tPA and plasminogen KO animals showed lower ability in secreting AVP into the blood circulation upon a chronic osmotic stimulation. The recombinant tPA was able to promote the release of AVP from isolated NH. Chronic osmotic stimulation decreased the laminin expression level of neurohypophysial microvessel in WT mice but not in plasminogen KO ones. We suggest that AVP secretion is critically regulated by tPA-dependent facilitation of AVP release from terminals and plasminogen-dependent increase of AVP permeability across microvessels possibly via laminin degradation.

Plasminogen is essential for granulation tissue formation during the recovery process after liver injury in mice

SUMMARY BACKGROUND

The involvement of plasminogen in liver repair has been reported, but its exact role in promoting this process is unknown.

OBJECTIVE

To elucidate the underlying mechanism, we examined the dynamics of liver repair by using a reproducible liver injury model in plasminogen gene-deficient mice and their wild-type littermates.

METHODS

Liver injury was induced by photochemical reaction and the subsequent responses were histologically analyzed.

RESULTS

In wild-type animals, the area of the damage successively decreased, and the repair process was associated with macrophage accumulation at its border. Neutrophils were also attracted to the damaged region on day 1 and were evident only at its border by day 4, which spatially and temporally coincided with the expression of macrophage chemoattractant protein-1 (MCP-1). Neutrophil depletion suppressed recruitment of macrophages at the border between the damaged and the normal tissues. These changes were followed by activated hepatic stellate cell accumulation, collagen fiber deposition and angiogenesis at the boundaries of the injured zone. In contrast, in plasminogen gene-deficient mice, the decrease in the area of damage, macrophage accumulation, late-phase neutrophil recruitment, hepatic stellate cell accumulation, collagen fiber deposition and angiogenesis were all impaired.

CONCLUSION

Our data suggest that accumulated neutrophils at the border of the damaged area may contribute to macrophage accumulation at granulation tissue via the production of MCP-1 after liver injury. The plasminogen system is critical for liver repair by facilitating macrophage accumulation and triggering a cascade of subsequent repair events.

alpha2-antiplasmin is associated with the progression of fibrosis

Systemic sclerosis results in tissue fibrosis due to the activation of fibroblasts and the ensuing overproduction of the extracellular matrix. We previously reported that the absence of alpha2-antiplasmin (alpha2AP) attenuated the process of dermal fibrosis; however, the detailed mechanism of how alpha2AP affects the progression of fibrosis remained unclear. The goal of the present study was to examine the role of alpha2AP in fibrotic change. We observed significantly higher levels of alpha2AP expression in the skin of bleomycin-injected systemic sclerosis model mice in comparison with the levels seen in control mice. We also demonstrated that alpha2AP induced myofibroblast differentiation, and the absence of alpha2AP attenuated the induction of myofibroblast differentiation. Moreover, we found that connective tissue growth factor induced the expression of alpha2AP through both the extracellular signal-regulated kinase 1/2 (ERK1/2) and c-Jun N-terminal kinase (JNK) pathways in fibroblasts. Interestingly, alpha2AP also induced transforming growth factor-beta expression through the same pathways, and the inhibition of ERK1/2 and JNK slowed the progression of bleomycin-induced fibrosis. Our findings suggest that alpha2AP is associated with the progression of fibrosis, and regulation of alpha2AP expression by the ERK1/2 and JNK pathways may be an effective antifibrotic therapy for the treatment of systemic sclerosis.

Alpha2-Antiplasmin Is a Critical Regulator of Angiotensin II–Mediated Vascular Remodeling

Objective— Alpha2-antiplasmin (α2-AP) is the major circulating inhibitor of plasmin, which plays a determining role in the regulation of intravascular fibrinolysis. We investigated the role of α 2 -AP on vascular remodeling in response to angiotensin II (Ang II).

Methods and Results— α2-AP–deficient mice were performed. Ang II and N ω -nitro- L-arginine methyl ester (L-NAME)–induced perivascular fibrosis was significantly decreased in α2-AP −/− mice compared with wild-type mice. In situ gelatinolytic activity analysis shows that perivascular gelatinolytic activity was increased in α2-AP −/− mice, which was responsible for decreased perivascular fibrosis in response to Ang II and L-NAME. Ang II–induced arterial wall thickening, vascular cell proliferation, apoptosis, c-Myc, and collagen Ι expression were significantly decreased in α2-AP −/− mice compared with wild-type mice. Further analysis shows that increased p53 and p21 expression were responsible for inhibition of Ang II–induced vascular remodeling in α2-AP −/− mice.

Conclusion— The results show that α2-AP is a critical regulator for vascular remodeling by inhibiting p53/p21 pathway, suggesting that α2-AP is proposed to be a potential therapeutic target for vascular remodeling.

Characterization of non-linear relationship between total and unbound serum concentrations of valproic acid in epileptic children

OBJECTIVE

To establish a regression equation to properly estimate the unbound serum concentration of valproic acid (VPA) from its total serum concentration; the relationship between total and unbound serum VPA concentrations was retrospectively characterized.

METHODS

Data were obtained from the clinical examination records that were routinely archived during therapeutic drug monitoring. The screening encompassed 342 records of 108 paediatric patients whose total and unbound VPA concentrations had been determined. The relationship between total and unbound VPA concentrations was characterized according to the Langmuir equation by taking account of inter-individual variability with the nonmem program.

RESULTS

The total VPA concentration (C(t)) in the screened patients ranged from 5.5 to 179.8 microg/mL, and the unbound VPA concentration (C(f)) increased in a non-linear manner as the total VPA concentration increased. Taking account of the effects of antiepileptics concurrently administered, the VPA dissociation constant (K(d)) and maximum binding site concentration (B(m)) were 7.8 +/- 0.7 and 130 +/- 4.5 microg/mL respectively, for the regression equation, C(t) = C(f) + B(m) x C(f)/(K(d) + C(f)). An alteration in the unbound concentration was seen in patients who were treated with the combination of VPA and ethosuximide and in those who received two additional antiepileptics.

CONCLUSIONS

A regression equation for estimation of the unbound VPA concentration, based on total VPA concentration collected during routine therapeutic drug monitoring was established. Use of two additional antiepileptics and ethosuximide treatment was considered as potential factors affecting unbound VPA concentration.

Alpha2-antiplasmin is involved in the production of transforming growth factor beta1 and fibrosis

BACKGROUND

Fibrotic disease occurs in most tissues. Transforming growth factor (TGF)-beta is the major inducer of fibrosis. The fibrinolytic system is considered to play an important role in the degradation of extracellular matrices. However, the detailed mechanism of how this system affects fibrosis remains unclear.

METHODS AND RESULTS

We examined experimental fibrosis in mice with a deficiency of alpha(2)-antiplasmin (alpha2AP), which is a potent and specific plasmin inhibitor. We found that the lack of alpha2AP attenuated bleomycin-induced TGF-beta(1) synthesis and fibrosis. In addition, the production of TGF-beta(1) from the explanted fibroblasts of alpha2AP(-/-) mice decreased dramatically as compared to that in wild-type mice. Moreover, we found that alpha2AP specifically induces the production of TGF-beta(1) in fibroblasts.

CONCLUSION

The lack of alpha2AP attenuated TGF-beta(1) synthesis, thereby resulting in attenuated fibrosis. This is the first report to describe the crucial role that alpha2AP plays in TGF-beta(1) synthesis during the process of fibrosis. Our results provide new insights into the role of alpha2AP in fibrosis.

Mesenchymal progenitor cells in adult human dental pulp and their ability to form bone when transplanted into immunocompromised mice

The technique of tissue engineering is developing for the restoration of lost tissues. This new technique requires cells that fabricate tissue. Mesenchymal stem cells in bone marrow have been used as the cell source for this technique; however, dental pulp cells have recently been shown to possess stem-cell-like properties. We earlier demonstrated that dental pulp cells proliferate and produce an extracellular matrix that subsequently becomes mineralized in vitro. We now report that such dental pulp cells (first to eighth passage) produced bone instead of dentin when those cells were implanted into subcutaneous sites in immunocompromised mice with HA/TCP powder as their carrier. This evidence shows that dental pulp cells are the common progenitors of odontoblasts and osteoblasts, or dental pulp cells are mesenchymal stem cells themselves. It is expected that dental pulp cells can be a useful candidate cell source for tissue engineering, and contain the potential of new therapeutic approaches for the restoration of damaged or diseased tissue.

c-Myc is essential for urokinase plasminogen activator expression on hypoxia-induced vascular smooth muscle cells

OBJECTIVES

The purpose of this study was to investigate whether c-Myc regulates expression of urokinase plasminogen activator (uPA) on hypoxia-induced vascular smooth muscle cells (VSMCs).

METHODS

VSMCs were isolated from thoracic aorta of wild-type (WT), tissue plasminogen activator (tPA) and uPA-deficient mice. Gene and protein expression levels were examined by reverse-transcription PCR and Western blotting, respectively. c-Myc and uPA transcriptional activity were determined by luciferase analysis. Zymography analysis was used to test the activity of matrix metalloproteinases (MMPs), tPA, and uPA.

RESULTS

Hypoxia significantly promoted WT and tPA-/- VSMC migration and invasion. However, uPA-/- severely decreased hypoxia-induced VSMC migration and invasion. Hypoxia increased uPA and MMP-2 activity, while uPA-/- decreased hypoxia-induced MMP-2 activity. c-Myc expression and transcriptional activity were increased in response to hypoxia, and silenced c-Myc abolished hypoxia-induced uPA and MMP-2 activity. In addition, hypoxia-induced Bcl2 expression and Bcl2 binding to c-Myc led to enhanced c-Myc-mediated uPA and MMP-2 activity in response to hypoxia.

CONCLUSIONS

The results show that c-Myc was essential for hypoxia-induced uPA expression and activity, resulting in VSMC migration and invasion. In addition, Bcl2 enhanced the c-Myc-mediated uPA/MMP-2 pathway.

Plasmin decreases the BH3-only protein BimEL via the ERK1/2 signaling pathway in hepatocytes

Since the signal transduction mechanisms responsible for liver regeneration mediated by the plasminogen/plasmin system remain largely undetermined, we have investigated whether plasmin regulates the pro-apoptotic protein Bim(EL) in primary hepatocytes. Plasmin bound to hepatocytes in part via its lysine binding sites (LBS). Plasmin also triggered phosphorylation of ERK1/2 without cell detachment. The plasmin-induced phosphorylation of ERK1/2 was inhibited by the LBS inhibitor epsilon-aminocaproic acid (EACA), the serine protease inhibitor aprotinin, and the MEK inhibitor PD98059. DFP-inactivated plasmin failed to phosphorylate ERK1/2. Plasmin temporally decreased the starvation-induced expression of Bim(EL) and activation of caspase-3 via the ERK1/2 signaling pathway, resulting in an enhancement of cell survival. The amount of mRNA for Bim increased 1 day after the injection of CCl(4) in livers of plasminogen knockout (Plg-KO) and the wild-type (WT) mice. The increase in Bim(EL) protein persisted for at least 7 days post-injection in livers of Plg-KO mice, whereas WT mice showed an increase in Bim(EL) protein 1 day after the injection. Plg-KO and WT mice showed notable phosphorylation of ERK1/2 7 and 3 days after the injection of CCl(4), respectively. Our data suggest that the plasminogen/plasmin system could decrease Bim(EL) expression via the ERK1/2 signaling pathway during liver regeneration.

Effect of staphylokinase-derived nonadecapeptide on the activation of plasminogen

Staphylokinase (SAK) expresses plasminogen activator (PA) activity by forming a complex with plasmin. The interaction between the plasmin-SAK complex and plasminogen was investigated using synthesized peptides, which were constructed according to the amino acid sequence of the SAK molecule. A synthetic nonadecapeptide (SAK22-40) corresponding to Glu22-Leu40 by the SAK molecule enhanced the activation of Glu-plasminogen by the plasmin-SAK complex. Analysis of IAsys resonant mirror biosensor showed that SAK22-40 bound to Glu-plasminogen. This binding was completely inhibited by IgG against the B-chain in the plasminogen molecule. But, this binding was not inhibited by IgG against lysine-binding sites (LBS) of the A-chain in the plasminogen molecule. The substitution of Lys35 with Ala in SAK22-40 did not enhance the activation of Glu-plasminogen by the plasmin-SAK complex. When SAK22-40 was administrated in a mouse thrombosis model, earlier recanalization was observed than in mice with vehicle administration. Thus, a newly synthesized peptide, SAK22-40 enhanced Glu-plasminogen activation and induced effective thrombolysis.