New synthetic inhibitors of C1r, C1 esterase, thrombin, plasmin, kallikrein and trypsin

Nafamostat mesilate negatively regulates the metastasis of triple-negative breast cancer cells

Triple-negative breast cancer (TNBC) lacking of oestrogen receptor, progesterone receptor, and epidermal growth factor receptor type 2 is a highly malignant disease which results in a poor prognosis and rare treatment options. Despite the use of conventional chemotherapy for TNBC tumours, resistance and short duration responses limit the treatment efficacy. Therefore, a need exists to develop a new chemotherapy for TNBC. The aim of this study was to examine the anti-cancer effects of nafamostat mesilate (NM), a previously known serine protease inhibitor and highly safe drug on breast cancer cells. Here, we showed that NM significantly inhibits proliferation, migration, and invasion in MDA-MB231 cells, induces G2/M phase cell-cycle arrest, and inhibits the expression of cyclin-dependent kinase 1 (CDK1). Exposure of MDA-MB231 cells to NM also resulted in decreased transcription factor activities accompanied by the regulated phosphorylation of signalling molecules and a decrease in metalloproteinases, the principal modulators of the extracellular environment during cancer progression. Especially, inhibition of TGFβ-stimulated Smad2 phosphorylation and subsequent metastasis-related gene expression, and downregulation of ERK activity may be pivotal mechanisms underlying inhibitory effects of NM on NM inhibits lung metastasis of breast cancer cells and growth of colonized tumours in mice. Taken together, our data revealed that NM inhibits cell growth and metastasis of TNBC cells and indicated that NM is a multi-targeted drug that could be an adjunct therapy for TNBC treatment.

On the value of therapeutic interventions targeting the complement system in acute myocardial infarction

The complement system plays an important role in the inflammatory response subsequent to acute myocardial infarction (AMI). The aim of this study is to create a systematic overview of studies that have investigated therapeutic administration of complement inhibitors in both AMI animal models and human clinical trials. To enable extrapolation of observations from included animal studies toward post-AMI clinical trials, ex vivo studies on isolated hearts and proof-of-principle studies on inhibitor administration before experimental AMI induction were excluded. Positive therapeutic effects in AMI animal models have been described for cobra venom factor, soluble complement receptor 1, C1-esterase inhibitor (C1-inh), FUT-175, C1s-inhibitor, anti-C5, ADC-1004, clusterin, and glycosaminoglycans. Two types of complement inhibitors have been tested in clinical trials, being C1-inh and anti-C5. Pexelizumab (anti-C5) did not result in reproducible beneficial effects for AMI patients. Beneficial effects were reported in AMI patients for C1-inhibitor, albeit in small patient groups. In general, despite the absence of consistent positive effects in clinical trials thus far, the complement system remains a potentially interesting target for therapy in AMI patients. Based on the study designs of previous animal studies and clinical trials, we discuss several issues which require attention in the design of future studies: adjustment of clinical trial design to precise mechanism of action of administered inhibitor, optimizing the duration of therapy, and optimization of time point(s) on which therapeutic effects will be evaluated.

Treatment of sepsis by plasma endotoxin removal: hemoperfusion using a polymyxin-B immobilized column

A Phase I clinical trial was carried out to evaluate the effects of endotoxin elimination by direct hemoperfusion using a cartridge containing chemically immobilized polymyxin B fibers (PMX-F). Thirty-seven endotoxemic patients with multiple organ failure (MOF) were treated. Direct hemoperfusion for 2 h using a PMX-F column was performed (PMX). PMX could remove circulating endotoxin from severely endotoxemic patients. Plasma endotoxin level was significantly decreased between its inlet and outlet level of PMX-F column ( P < 0.01). The mean plasma endotoxin concentration of all PMX ( n = 51) was 83.7 ± 26.7 pg/ml before PMX, and significantly decreased to 56.4 ± 27.9 after ( P < 0.01). Plasma endotoxin was significantly decreased in survivors, but that of non-survivors did not change with PMX ( P < 0.05). Body temperature, blood pressure, cardiac index, systemic vascular resistance and the oxygen consumption index improved significantly after PMX. Inotropic and vasopressive drugs were discontinued or reduced with PMX. PMX treatment showed a correlation between reduction of plasma endotoxin level and the improvement of septic syndrome, especially cardiovascular impairments. Also, this new therapy seemed to influence the outcome of severe sepsis or septic MOF patients with endotoxemia.

A Synthetic Serine Protease Inhibitor, Nafamostat Mesilate, Is a Drug Potentially Applicable to the Treatment of Ebola Virus Disease

Ebola virus disease (EVD) has been a great concern worldwide because of its high mortality. EVD usually manifests with fever, diarrhea and vomiting, as well as disseminated intravascular coagulation (DIC). To date, there is neither a licensed Ebola vaccine nor a promising therapeutic agent, although clinical trials are ongoing. For replication inside the cell, Ebola virus (EBOV) must undergo the proteolytic processing of its surface glycoprotein in the endosome by proteases including cathepsin B (CatB), followed by the fusion of the viral membrane and host endosome. Thus, the proteases have been considered as potential targets for drugs against EVD. However, no protease inhibitor has been presented as effective clinical drug against it. A synthetic serine protease inhibitor, nafamostat mesilate (NM), reduced the release of CatB from the rat pancreas. Furthermore, it has anticoagulant activities, such as inhibition of the factor VIIa complex, and has been used for treating DIC in Japan. Thus, NM could be considered as a drug candidate for the treatment of DIC induced by EBOV infection, as well as for the possible CatB-related antiviral action. Moreover, the drug has a history of large-scale production and clinical use, and the issues of safety and logistics might have been cleared. We advocate in vitro and in vivo experiments using active EBOV to examine the activities of NM against the infection and the DIC induced by the infection. In addition, we suggest trials for comparison among anti-DIC drugs including the NM in EVD patients, in parallel with the experiments.

Pathophysiological roles of proteases in gastrointestinal disease

Gastrointestinal diseases, such as irritable bowel syndrome, inflammatory bowel disease, and colorectal cancer, affect a large proportion of the population and are associated with many unpleasant symptoms. Although the causes of these diseases remain largely unknown, there is increasing evidence to suggest that dysregulated protease activity may be a contributing factor. Proteases are enzymes that cleave other proteins, and their activity is normally very tightly regulated. During disease, however, the balance between proteases and their inhibitors is often shifted, leading to altered spatial and temporal control of substrate cleavage. Evaluating protease levels in normal physiology and disease has relied heavily on the use of chemical tools. Although these tools have greatly advanced the field, they are not without caveats. This review provides an introduction to these tools, their application in the gut, and a summary of the current knowledge on the contribution of protease activity to gastrointestinal disease.

Nafamostat mesilate protects against acute cerebral ischemia via blood-brain barrier protection

Serine proteases, such as thrombin, are contributors to the disruption of the blood-brain barrier (BBB) and exacerbate brain damage during ischemic stroke, for which the current clinical therapy remains unsatisfactory. However, the effect of nafamostat mesilate (NM), a synthetic serine protease inhibitor, on BBB disruption following cerebral ischemia is unknown. Here, we investigated the in vivo effect of NM on BBB integrity in rats subjected to transient middle cerebral artery occlusion (MCAO) and explored the possible mechanism in an in vitro BBB model comprising rat brain microvascular endothelial cells and astrocytes after oxygen and glucose deprivation (OGD) in the presence of thrombin. The results showed that NM treatment remarkably attenuated transient MCAO-induced brain infarcts, brain oedema and motor dysfunction in addition to BBB disruption, which might be related to changes in tight junction protein expression and localization. Meanwhile, NM preserved BBB integrity and alleviated the changes in tight junction protein expression and localization and cytoskeleton rearrangement in rat brain microvascular endothelial cells via thrombin inhibition. Our findings suggest that NM treatment can preserve BBB integrity through the inhibition of thrombin, which might be correlated with the regulation of PKCα/RhoA/MLC2 pathway components.

Nafamostat Mesilate as a Regional Anticoagulant in Patients with Bleeding Complications during Extracorporeal Membrane Oxygenation

Purpose

Anticoagulation is mandatory for extracorporeal membrane oxygenation (ECMO), but systemic heparinization, which has been most widely used as an anticoagulant, has been associated with bleeding complications. The present study reviewed the usefulness and safety of nafamostat mesilate as a regional anticoagulant in patients with bleeding complication during ECMO.

Methods

We retrospectively reviewed the record of 13 cases. The nafamostat mesilate dose was regulated to maintain the activated clotting time (ACT) or activated partial thromboplastin time (aPTT) values within an adequate range at the ECMO reinfusion route. ACT or aPTT values in blood samples from the ECMO circuit and from the patients were measured simultaneously and consecutively.

Results

We measured the ACT value in 6 cases and aPTT in 7 cases. The bleeding complications were treated in 11 cases. When we compared the difference in 2 anticoagulation values (ACT and aPTT) between the 2 blood samples, one taken from ECMO and the other from patients, mean anticoagulation values of blood from patients were lower than those from ECMO circuit in 11 cases. With respect to the type of ECMO reinfusion mode, the difference was significant only in veno-arterial mode ECMO group (p<0.001).

Conclusions

Nafamostat mesilate, with which we can reduce anticoagulation values of patient to a safe level without losing the ECMO anticoagulation values is expected to be useful as a regional anticoagulant in patients with bleeding complications or a high risk of bleeding during ECMO.

Nafamostat Mesilate as an Anticoagulant During Continuous Renal Replacement Therapy in Patients With High Bleeding Risk: A Randomized Clinical Trial

Nafamostat mesilate (NM), a synthetic serine protease inhibitor, has been used increasingly as an anticoagulant during continuous renal replacement therapy (CRRT). However, there, are limited data from randomized studies on NM use in patients with a bleeding tendency. This prospective study evaluated the efficacy and safety of NM use during CRRT in patients with acute kidney injury (AKI) patients at high risk of bleeding.Patients with AKI at high risk of bleeding were randomized into the NM and no anticoagulant (NA) groups. The primary outcome was the treatment efficacy represented by the filter lifespan. Several parameters, including safety and patient survival rates at 30 and 90 days, were analyzed as secondary outcomes.Fifty-five patients were included in this study (NM group = 31, NA group = 24). The baseline characteristics did not significantly differ between the groups. The mean filter lifespan was significantly longer in the NM group than in the NA group (31.7 ± 24.1 versus 19.5 ± 14.9 hours; P = 0.035). The most common cause of filter failure was filter clotting, which was significantly more frequent in the NA group than in the NM group (59.6% versus 37.7%, P = 0.024). The Cox proportional hazards model showed a 42.2% longer filter lifespan in the NM group compared with the NA group (hazard ratio, 0.578; 95% confidence interval, 0.362-0.923; P = 0.022). There were no significant differences in the frequencies of transfusions and major bleeding between the groups. Patient survival rates at 30 and 90 days after CRRT initiation were comparable between the groups.Nafamostat mesilate is a safe and effective anticoagulant for CRRT and allows sufficient filter survival without increasing the risk of bleeding in critically ill patients with AKI and bleeding tendencies.

Cardiac arrest caused by nafamostat mesilate

A 65-year-old man was transferred from the Department of Vascular Surgery to Nephrology because of cardiac arrest during hemodialysis. He underwent incision and drainage for treatment of a buttock abscess. Nafamostat mesilate was used as an anticoagulant for hemodialysis to address bleeding from the incision and drainage site. Sudden cardiac arrest occurred after 15 minutes of dialysis. The patient was treated in the intensive care unit for 5 days. Continuous veno-venous hemodiafiltration was started without any anticoagulant in the intensive care unit. Conventional hemodialysis was reinitiated, and nafamostat mesilate was used again because of a small amount of continued bleeding. Ten minutes after hemodialysis, the patient complained of anaphylactic signs and symptoms such as dyspnea, hypotension, and facial swelling. Epinephrine, dexamethasone, and pheniramin were injected under the suspicion of anaphylactic shock, and the patient recovered. Total immunoglobulin E titer was high, and skin prick test revealed weak positivity for nafamostat mesilate. We first report a case of anaphylactic shock caused by nafamostat mesilate in Korea.

Nafamostat mesilate for prevention of post-ERCP pancreatitis: a meta-analysis of prospective, randomized, controlled trials

OBJECTIVES

We aimed to evaluate the efficacy of nafamostat on the prevention of post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis (PEP).

METHODS

Medline, Embase, Cochrane Central Register of Controlled Trials, and Web of Science were searched until April 18, 2014.

RESULTS

Seven randomized controlled trials and 2956 patients met the search criteria. When compared with nonnafamostat, the incidence of PEP was reduced to 53% in the patients who received nafamostat (risk ratio [RR], 0.47; 95% confidence interval [CI], 0.34-0.63). Further analyses were conducted based on the different risk classifications (n = 641 in patients with high risks: RR, 0.54; 95% CI, 0.30-0.96 and n = 944 with low risks: RR, 0.31; 95% CI, 0.17-0.56), PEP severities (n = 1654: RR, 0.38; 95% CI, 0.25-0.59 for mild; RR, 0.37; 95% CI, 0.15-0.96 for moderate; RR, 0.92; 95% CI, 0.13-6.38 for severe), and nafamostat doses (n = 1902: RR, 0.42; 95% CI, 0.28-0.63 for 20 mg; n = 1150: RR, 0.40; 95% CI, 0.25-0.63 for 50 mg). However, there was no reduction of the incidence of post-ERCP hyperamylasemia (n = 1585; 95% CI, 0.68-1.45) or cannulation difficulty (n = 1585; 95% CI, 0.91-1.23).

CONCLUSIONS

Pooled analyses from current randomized controlled trials support the effectiveness of nafamostat for prophylaxis of PEP.

Polyphenol extract from Phellinus igniarius protects against acrolein toxicity in vitro and provides protection in a mouse stroke model

The basidiomycetous mushroom Phellinus igniarius (L.) Quel. has been used as traditional medicine in various Asian countries for many years. Although many reports exist on its anti-oxidative and anti-inflammatory activities and therapeutic effects against various diseases, our current knowledge of its effect on stroke is very limited. Stroke is a neurodegenerative disorder in which oxidative stress is a key hallmark. Following the 2005 discovery by Igarashi's group that acrolein produced from polyamines in vivo is a major cause of cell damage by oxidative stress, we now describe the effects of anti-oxidative extracts from P. igniarius on symptoms of experimentally induced stroke in mice. The toxicity of acrolein was compared with that of hydrogen peroxide in a mouse mammary carcinoma cell line (FM3A). We found that the complete inhibition of FM3A cell growth by 5 μM acrolein could be prevented by crude ethanol extract of P. igniarius at 0.5 μg/ml. Seven polyphenol compounds named 3,4-dihydroxybenzaldehyde, 4-(3,4-dihydroxyphenyl-3-buten-2one, inonoblin C, phelligridin D, inoscavin C, phelligridin C and interfungin B were identified from this ethanolic extract by LCMS and 1H NMR. Polyphenol-containing extracts of P. igniarius were then used to prevent acrolein toxicity in a mouse neuroblastoma (Neuro-2a) cell line. The results suggested that Neuro-2a cells were protected from acrolein toxicity at 2 and 5 μM by this polyphenol extract at 0.5 and 2 μg/ml, respectively. Furthermore, in mice with experimentally induced stroke, intraperitoneal treatment with P. igniarius polyphenol extract at 20 μg/kg caused a reduction of the infarction volume by 62.2% compared to untreated mice. These observations suggest that the polyphenol extract of P. igniarius could serve to prevent ischemic stroke.

International Union of Basic and Clinical Pharmacology. XCI. structure, function, and pharmacology of acid-sensing ion channels and the epithelial Na+ channel

The epithelial Na(+) channel (ENaC) and the acid-sensing ion channels (ASICs) form subfamilies within the ENaC/degenerin family of Na(+) channels. ENaC mediates transepithelial Na(+) transport, thereby contributing to Na(+) homeostasis and the maintenance of blood pressure and the airway surface liquid level. ASICs are H(+)-activated channels found in central and peripheral neurons, where their activation induces neuronal depolarization. ASICs are involved in pain sensation, the expression of fear, and neurodegeneration after ischemia, making them potentially interesting drug targets. This review summarizes the biophysical properties, cellular functions, and physiologic and pathologic roles of the ASIC and ENaC subfamilies. The analysis of the homologies between ENaC and ASICs and the relation between functional and structural information shows many parallels between these channels, suggesting that some mechanisms that control channel activity are shared between ASICs and ENaC. The available crystal structures and the discovery of animal toxins acting on ASICs provide a unique opportunity to address the molecular mechanisms of ENaC and ASIC function to identify novel strategies for the modulation of these channels by pharmacologic ligands.

Pharmacologic prophylaxis of post-endoscopic retrograde cholangiopancreatography pancreatitis: protease inhibitors and NSAIDs in a meta-analysis

Post-endoscopic retrograde cholangiopancreatography (ERCP) pancreatitis is the most frequent complication of ERCP. Several meta-analyses have examined the effects of protease inhibitors (gabexate mesilate, ulinastatin, and nafamostat mesilate) and non-steroidal anti-inflammatory drugs (NSAIDs) on post-ERCP pancreatitis, but the results have been confusing. Since the previous meta-analysis, several new studies have been published on this topic. To provide an updated quantitative assessment of the effectiveness of protease inhibitors and NSAIDs in preventing post-ERCP pancreatitis, we conducted a meta-analysis of randomized trials for patients at risk of post-ERCP pancreatitis. Twenty-six articles were included in this meta-analysis. Nafamostat mesilate (summary RR = 0.41; 95 %CI 0.28-0.59; n = 4 studies) and NSAIDs (summary RR = 0.58; 95 %CI = 0.44-0.76; n = 7 studies) were associated with decreased risk of post-ERCP pancreatitis in the high-quality studies. However, gabexate mesilate (summary RR = 0.64; 95 %CI = 0.36-1.13; n = 6 studies) and ulinastatin (summary RR = 0.65; 95 %CI = 0.33-1.30; n = 2 studies) were not associated with decreased risk of post-ERCP pancreatitis in the high-quality studies. This is the first meta-analysis to compare the effects of three protease inhibitors. Solid evidence supports the use of nafamostat mesilate and NSAIDs for preventing post-ERCP pancreatitis.

A specific assay for quantification of human C4c by use of an anti-C4c monoclonal antibody

The increasing evidence of the implication of the complement system in the pathogenesis of several diseases has emphasized the need for the development of specific and valid assays, optimized for quantitative detection of complement activation in vivo. In the present study, we have developed a mouse monoclonal antibody (mAb) that is able to detect fluid phase C4c without interference from other products generated from the complement component C4. The C4c specific mAb was tested in different enzyme-linked immunosorbent assay (ELISA) combinations with various types of in vitro activated sera and samples from factor I deficient patients. The specificity of the mAb was further evaluated by immunoprecipitation techniques and by analysis of eluted fragments of C4 after immunoaffinity chromatography. The anti-C4c mAb was confirmed to be C4c specific, as it showed no cross-reactivity with native (un-cleaved) C4, C4b, iC4b, or C4d. Also, no reaction was observed with C4 fragments in factor I deficient plasma or serum samples. We established and validated a sandwich ELISA based on this C4c specific antibody. The normal range of C4c in EDTA/futhan plasma collected from 100 Danish blood donors was measured, with a mean of 0.85mg/L and a range of 0.19-2.21mg/L. We believe that the C4c specific antibody and the ELISA might be important tools in the future assessment of in vivo activation in situations where the classical or the lectin complement pathways are involved in the pathogenesis.

Pancreatic digestive enzyme blockade in the intestine increases survival after experimental shock

Shock, sepsis, and multiorgan failure are associated with inflammation, morbidity, and high mortality. The underlying pathophysiological mechanism is unknown, but evidence suggests that pancreatic enzymes in the intestinal lumen autodigest the intestine and generate systemic inflammation. Blocking these enzymes in the intestine reduces inflammation and multiorgan dysfunction. We investigated whether enzymatic blockade also reduces mortality after shock. Three rat shock models were used here: hemorrhagic shock, peritonitis shock induced by placement of cecal material into the peritoneum, and endotoxin shock. One hour after initiation of hemorrhagic, peritonitis, or endotoxin shock, animals were administered one of three different pancreatic enzyme inhibitors--6-amidino-2-naphtyl p-guanidinobenzoate dimethanesulfate, tranexamic acid, or aprotinin--into the lumen of the small intestine. In all forms of shock, blockade of digestive proteases with protease inhibitor attenuated entry of digestive enzymes into the wall of the intestine and subsequent autodigestion and morphological damage to the intestine, lung, and heart. Animals treated with protease inhibitors also survived in larger numbers than untreated controls over a period of 12 weeks. Surviving animals recovered completely and returned to normal weight within 14 days after shock. The results suggest that the active and concentrated digestive enzymes in the lumen of the intestine play a central role in shock and multiorgan failure, which can be treated with protease inhibitors that are currently available for use in the clinic.

Effect of nafamostat on N-methyl-D-aspartate-induced retinal neuronal and capillary degeneration in rats

We examined the effects of the serine protease inhibitor nafamostat mesilate on neuronal and vascular injury in rat retinas treated with N-methyl-D-aspartate (NMDA). The degree of neuronal degeneration was assessed by measuring the number of cells in the ganglion cell layer and the thickness of the inner plexiform layer. The degree of capillary degeneration was assessed by measuring the number of empty basement membrane sleeves that were left as remnants of the vessels. Significant neuronal and capillary degeneration was observed 7 d after a single intravitreal injection of NMDA into the eye. Both forms of degeneration were significantly prevented by simultaneous injection of nafamostat mesilate with NMDA. These results indicate that nafamostat mesilate affords protection against the neuro/vascular injury seen in NMDA-treated retinas. Nafamostat mesilate may be considered as a candidate for neuro/vascular protective interventions in retinal diseases associated with glutamate-induced excitotoxicity, such as glaucoma and diabetic retinopathy.

Combination chemotherapy of serine protease inhibitor nafamostat mesilate with oxaliplatin targeting NF-κB activation for pancreatic cancer

In this study, we assessed if nafamostat mesilate may enhance anti-tumor effects of oxaliplatin on Panc-1 cells and pancreatic cancer mouse model. In combination treatment with nafamostat mesilate and oxaliplatin, NF-κB activation was inhibited by suppressing IκBα phosphorylation, and caspase-8-mediated apoptosis was more prominent than that treated with oxaliplatin alone, both in vitro and in vivo. Nafamostat mesilate reduced proliferation rate of Panc-1 cells as compared with oxaliplatin alone in vitro and enhanced oxaliplatin-induced tumor growth inhibition in vivo. Combination chemotherapy using nafamostat mesilate and oxaliplatin induces synergistic cytotoxicity in pancreatic cancer and could be a novel strategy for treatment.

Inhibition of nuclear factor-κB enhances the antitumor effect of paclitaxel against gastric cancer with peritoneal dissemination in mice

BACKGROUND

Intraperitoneal (i.p.) administration of paclitaxel is useful for treating malignant tumors with peritoneal dissemination, but the therapeutic efficacy is limited. Chemoresistance due to paclitaxel-induced nuclear factor-kappa B (NF-κB) activation is an important cause of suboptimal therapeutic efficacy.

AIMS

The purpose of this study was to prove that addition of nafamostat mesilate (FUT-175), a synthetic serine protease inhibitor and an NF-κB inhibitor, to i.p. paclitaxel enhances antitumor effects of paclitaxel against gastric cancer with peritoneal dissemination.

METHODS

In vitro, we assessed NF-κB activity and apoptosis in response to treatment with FUT-175 alone, paclitaxel alone, or a combination of FUT-175 and paclitaxel in a human gastric cancer cell line (MKN-45). In vivo, we established peritoneal dissemination in nude mice by i.p. injection of MKN-45 cells. The animals received i.p. injections of FUT-175 alone three times a week (FUT-175 group), of paclitaxel alone once a week (paclitaxel group), or a combination of FUT-175 and paclitaxel (combination group) three times and once a week, respectively.

RESULTS

In the combination group, paclitaxel-induced NF-κB activation was inhibited and apoptosis was enhanced in comparison with those in the other groups both in vitro and in vivo. In the combination group, number and weight of peritoneal nodules were significantly lower than those in the paclitaxel group (p = 0.0009 and p = 0.0417, respectively). In the survival analysis, the combination group had a significantly better survival than the paclitaxel group (p = 0.0048).

CONCLUSION

FUT-175 enhances the antitumor effect of i.p. paclitaxel against gastric cancer with peritoneal dissemination by inhibiting NF-κB activation in mice.

Breakdown of mucin as barrier to digestive enzymes in the ischemic rat small intestine

Loss of integrity of the epithelial/mucosal barrier in the small intestine has been associated with different pathologies that originate and/or develop in the gastrointestinal tract. We showed recently that mucin, the main protein in the mucus layer, is disrupted during early periods of intestinal ischemia. This event is accompanied by entry of pancreatic digestive enzymes into the intestinal wall. We hypothesize that the mucin-containing mucus layer is the main barrier preventing digestive enzymes from contacting the epithelium. Mucin breakdown may render the epithelium accessible to pancreatic enzymes, causing its disruption and increased permeability. The objective of this study was to investigate the role of mucin as a protection for epithelial integrity and function. A rat model of 30 min splanchnic arterial occlusion (SAO) was used to study the degradation of two mucin isoforms (mucin 2 and 13) and two epithelial membrane proteins (E-cadherin and toll-like receptor 4, TLR4). In addition, the role of digestive enzymes in mucin breakdown was assessed in this model by luminal inhibition with acarbose, tranexamic acid, or nafamostat mesilate. Furthermore, the protective effect of the mucin layer against trypsin-mediated disruption of the intestinal epithelium was studied in vitro. Rats after SAO showed degradation of mucin 2 and fragmentation of mucin 13, which was not prevented by protease inhibition. Mucin breakdown was accompanied by increased intestinal permeability to FITC-dextran as well as degradation of E-cadherin and TLR4. Addition of mucin to intestinal epithelial cells in vitro protected against trypsin-mediated degradation of E-cadherin and TLR4 and reduced permeability of FITC-dextran across the monolayer. These results indicate that mucin plays an important role in the preservation of the mucosal barrier and that ischemia but not digestive enzymes disturbs mucin integrity, while digestive enzymes actively mediate epithelial cell disruption.

Protease inhibitor nafamostat mesilate attenuates complement activation and improves function of xenografts in a discordant lung perfusion model

BACKGROUND

Anti-complement activity of nafamostat mesilate (FUT-175) is strong including its variety of pharmacological effects. The effect of FUT-175 for xenografts in an ex vivo guinea pig-to-rat lung perfusion model was evaluated.

METHODS

Heparinized Lewis rat blood was used to perfuse the lungs in three groups (n = 6 each). Group I used Lewis rat left lung for donor, Group X used guinea pig left lung for donor, and Group XF used guinea pig left lung for donor, which was perfused with Lewis rat blood with 0.2 mg/ml of FUT-175. Complement activity causing 50% hemolysis (CH50) in the perfusion blood and pulmonary function either before or during perfusion were serially measured. Pathological assessments of the lungs were also carried out after perfusion.

RESULTS

The duration of satisfactory pulmonary function was significantly increased in Group XF. Complement activity causing 50% hemolysis in Group XF decreased more significantly compared to Group X. FUT-175 suppressed both the increase in pulmonary arterial pressure and airway resistance, and the decrease in dynamic lung compliance. In Group X, pathology showed intra-alveolar hemorrhage, perivascular edema, and medial thickening with endothelial swelling of the pulmonary arteries. In Group XF, less changes were observed compared to Group X. Group X showed deposition of IgM, IgG, and C3 at the endothelium of arteries, which was fewer in Group XF, and even fewer in Group I.

CONCLUSIONS

This study suggests that FUT-175 inhibited complement activation and improved lung xenograft function. FUT-175 ameliorates hyperacute rejection in a guinea pig-to-rat ex vivo xenogeneic lung perfusion model.

Nafamostat mesilate can prevent adhesion, invasion and peritoneal dissemination of pancreatic cancer thorough nuclear factor kappa-B inhibition

BACKGROUND

Constitutive activation of nuclear factor kappa-B (NF-κB) contributes to the aggressive behavior of pancreatic cancer. Over-expression of downstream target genes of NF-κB such as intercellular adhesion molecule-1 (ICAM-1), interleukin-8 (IL-8), vascular endothelial growth factor (VEGF) and matrix metalloproteinase-9 (MMP-9) leads to the promotion of cell adhesion, angiogenesis, invasion and metastasis. We previously reported that nafamostat mesilate, a synthetic serine protease inhibitor, blocks NF-κB activation in pancreatic cancer. We hypothesized that nafamostat mesilate may inhibit cell adhesion, angiogenesis, invasion and metastases in peritoneal dissemination of pancreatic cancer.

METHODS

In vitro, we assessed inhibition of NF-κB, phosphorylated IκBα, ICAM-1, VEGF and MMP-9 activity by nafamostat mesilate using human pancreatic cancer cell lines (AsPC-1, BxPC-3 and PANC-1). Changes in adhesion and invasion abilities of cancer cells were then evaluated by nafamostat mesilate treatment. In vivo, the efficacy of nafamostat mesilate treatment was assessed using peritoneal dissemination of pancreatic cancer in mice.

RESULTS

In vitro, nafamostat mesilate inhibited activities of NF-κB, phosphorylated IκBα, ICAM-1, VEGF and MMP-9. Moreover, nafamostat mesilate not only inhibited cell adhesion and invasion but also increased the sensitivity of anoikis. In vivo, tumor growth using AsPC-1 cells of the treatment group was significantly slower, and survival rate was significantly better, than those in control group (p < 0.05).

CONCLUSION

Nafamostat mesilate reduced peritoneal metastasis and prolonged survival of pancreatic cancer-bearing mice.

Anticomplement therapy

The complement system is an important part of innate immunity; however, as with other parts of the immune system, the complement system can become pathologically activated and create or worsen disease. Anticomplement reagents have been studied for several years, but only recently have they emerged as a viable therapeutic tool. Here, we describe the role of the complement system in a wide array of diseases, as well as the use of anticomplement therapy as treatment for these diseases in animal models and in human clinical trials. Specifically, we will discuss the role of anticomplement therapy in paroxysmal nocturnal hemoglobinuria, glomerulonephritis, and heart disease, including coronary artery disease, myocardial infarction, and coronary revascularization procedures such as percutaneous coronary angioplasty and coronary artery bypass graft surgery.

Use of nafamostat mesilate as an anticoagulant during extracorporeal membrane oxygenation

Although the incidence of bleeding complications during extracorporeal membrane oxygenator (ECMO) support has decreased in various trials, bleeding is still the most fatal complication. We investigated the ideal dosage and efficacy of nafamostat mesilate for use with ECMO in patients with acute cardiac or respiratory failure. We assessed 73 consecutive patients who received ECMO due to acute cardiac or respiratory failure between January 2006 and December 2009. To evaluate the efficacy of nafamostat mesilate, we divided the patients into 2 groups according to the anticoagulants used during ECMO support. All patients of nafamostat mesilate group were male with a mean age of 49.2 yr. Six, 3, 5, and 3 patients were diagnosed with acute myocardial infarction, cardiac arrest, septic shock, and acute respiratory distress syndrome, respectively. The mean dosage of nafamostat mesilate was 0.64 mg/kg/hr, and the mean duration of ECMO was 270.7 hr. The daily volume of transfused packed red blood cells, fresh frozen plasma, and cryoprecipitate and the number of complications related to hemorrhage and thrombosis was lower in the nafamostat mesilate group than in the heparin group. Nafamostat mesilate should be considered as an alternative anticoagulant to heparin to reduce bleeding complications during ECMO.

Combination paclitaxel and inhibitor of nuclear factor κB activation improves therapeutic outcome for model mice with peritoneal dissemination of pancreatic cancer

OBJECTIVES

Paclitaxel (PTX) is a useful treatment for peritoneal dissemination of malignant tumors. However, chemoresistance due to PTX-induced nuclear factor κB (NF-κB) activation is an important cause of suboptimal therapeutic effect. We previously reported nafamostat mesilate (FUT175) inhibits NF-κB activation and promotes apoptosis in pancreatic cancer. We hypothesized that addition of FUT175 to PTX may enhance the antitumor effect in peritoneal dissemination of pancreatic cancer.

METHODS

In vitro, we assessed NF-κB activity and apoptosis by the combination of FUT175 and PTX using human pancreatic cancer cell line (AsPc-1). In vivo, we established peritoneal dissemination in nude mice by intraperitoneal injection of AsPc-1 cells. The animals were treated with intraperitoneal injection thrice a week of FUT175, once a week of PTX, or a combination of thrice a week of FUT175 and once a week of PTX (combination group).

RESULTS

In the combination groups, PTX-induced NF-κB activation was inhibited, and apoptosis was enhanced in comparison with other groups both in vitro and in vivo. In the combination group, tumor growth, serum tumor marker, and survival rate were significantly better than those in other groups (P < 0.05).

CONCLUSIONS

Combination chemotherapy using PTX with FUT175 exerts an antitumor effect for peritoneal dissemination of pancreatic cancer.

Nafamostat mesilate for prevention of post-endoscopic retrograde cholangiopancreatography pancreatitis: a prospective, randomized, double-blind, controlled trial

OBJECTIVES

Pancreatitis is the most common major complication of endoscopic retrograde cholangiopancreatography (ERCP). Efforts have been made to identify pharmacologic agents capable of reducing its incidence and severity. The aim of this trial was to determine whether prophylactic nafamostat mesilate, a synthetic protease inhibitor, would reduce the frequency and severity of post-ERCP pancreatitis.

METHODS

A total of 286 patients were randomized to receive either intravenous nafamostat mesilate or placebo 60 minutes before ERCP and for 6 hours after ERCP. A database was prospectively collected by a defined protocol. Standardized criteria were used to diagnose and grade the severity of pancreatitis.

RESULTS

The groups were similar with regard to patient demographics and to patient and procedure risk factors for pancreatitis. The overall incidence of pancreatitis was 5.9%. It occurred in 4 (2.8%) of 143 patients in the nafamostat group and in 13 (9.1%) of 143 patients in the control group (P = 0.03). Pancreatitis was graded mild in 2.1% and moderate in 0.7% of the nafamostat group and mild in 7.0% and moderate in 2.1% of the control group. There was no significant difference between the groups in the severity of pancreatitis.

CONCLUSIONS

Prophylactic intravenous nafamostat mesilate reduces the frequency of post-ERCP pancreatitis.

The modulation of TRPM7 currents by nafamostat mesilate depends directly upon extracellular concentrations of divalent cations

Concentrations of extracellular divalent cations (Ca2+ and Mg2+) fall substantially during intensive synaptic transmission as well as during some pathophysiological conditions such as epilepsy and brain ischemia. Here we report that a synthetic serine protease inhibitor, nafamostat mesylate (NM), and several of its analogues, block recombinant TRPM7 currents expressed in HEK293T cells in inverse relationship to the concentration of extracellular divalent cations. Lowering extracellular Ca2+ and Mg2+ also evokes a divalent-sensitive non-selective cation current that is mediated by TRPM7 expression in hippocampal neurons. In cultured hippocampal neurons, NM blocked these TRPM7-mediated currents with an apparent affinity of 27 μM, as well as the paradoxical Ca2+ influx associated with lowering extracellular Ca2+. Unexpectedly, pre-exposure to NM strongly potentiated TRPM7 currents. In the presence of physiological concentrations of extracellular divalent cations, NM activates TRPM7. The stimulating effects of NM on TRPM7 currents are also inversely related to extracellular Ca2+ and Mg2+. DAPI and HSB but not netropsin, blocked and stimulated TRPM7. In contrast, mono-cationic, the metabolites of NM, p-GBA and AN, as well as protease inhibitor leupeptin and gabexate failed to substantially modulate TRPM7. NM thus provides a molecular template for the design of putative modulators of TRPM7.

New insights of an old defense system: structure, function, and clinical relevance of the complement system

The complement system was discovered a century ago as a potent defense cascade of innate immunity. After its first description, continuous experimental and clinical research was performed, and three canonical pathways of activation were established. Upon activation by traumatic or surgical tissue damage, complement reveals beneficial functions of pathogen and danger defense by sensing and clearing injured cells. However, the latest research efforts have provided a more distinct insight into the complement system and its clinical subsequences. Complement has been shown to play a significant role in the pathogenesis of various inflammatory processes such as sepsis, multiorgan dysfunction, ischemia/reperfusion, cardiovascular diseases and many others. The three well-known activation pathways of the complement system have been challenged by newer findings that demonstrate direct production of central complement effectors (for example, C5a) by serine proteases of the coagulation cascade. In particular, thrombin is capable of producing C5a, which not only plays a decisive role on pathogens and infected/damaged tissues, but also acts systemically. In the case of uncontrolled complement activation, “friendly fire” is generated, resulting in the destruction of healthy host tissue. Therefore, the traditional research that focuses on a mainly positive-acting cascade has now shifted to the negative effects and how tissue damage originated by the activation of the complement can be contained. In a translational approach including structure-function relations of this ancient defense system, this review provides new insights of complement-mediated clinical relevant diseases and the development of complement modulation strategies and current research aspects.

Design and screening of ASIC inhibitors based on aromatic diamidines for combating neurological disorders

Acid sensing ion channels (ASICs) are implicated in various brain functions including learning and memory and are involved in a number of neurological disorders such as pain, ischemic stroke, depression, and multiple sclerosis. We have recently defined ASICs as one of receptor targets of aromatic diamidines in neurons. Aromatic diamidines are DNA-binding agents and have long been used in the treatment of leishmaniasis, trypanosomiasis, pneumocystis pneumonia and babesiosis. Moreover, some aromatic diamidines are used as skin-care and baby products and others have potential to suppress tumor growth or to combat malaria. A large number of aromatic diamidines or analogs have been synthesized. Many efforts are being made to optimize the therapeutic spectrum of aromatic diamidines, i.e. to reduce toxicity, increase oral bioavailability and enhance their penetration of the blood-brain barrier. Aromatic diamidines therefore provide a shortcut of screening for selective ASIC inhibitors with therapeutic potential. Intriguingly nafamostat, a protease inhibitor for treating acute pancreatitis, also inhibits ASIC activities. Aromatic diamidines and nafamostat have many similarities although they belong to distinct classes of medicinal agents for curing different diseases. Here we delineate background, clinical application and drug development of aromatic diamidines that could facilitate the screening for selective ASIC inhibitors for research purposes. Further studies may lead to a drug with therapeutic value and extend the therapeutic scope of aromatic diamidines to combat neurological diseases.

Pretreatment with nafamostat mesilate, a kallikrein inhibitor, to decrease withdrawal response associated with rocuronium

PURPOSE

This randomized, double-blind, placebo-controlled study was conducted to examine the preventive effect of nafamostat mesilate, a kallikrein inhibitor, on the withdrawal response associated with rocuronium injection.

METHODS

Ninety American Society of Anesthesiology (ASA) physical status I or II patients, aged 18-65 years, were randomly divided into two groups that received either a 1.5-ml solution containing 1.5 mg nafamostat mesilate diluted in a 5% glucose solution or a 1.5-ml 5% glucose solution. Anesthesia was induced by 5 mg/kg 2.5% thiopental. After confirming loss of consciousness, a tourniquet was applied to the mid forearm and tightened to block venous flow. The test solution was then administered, 1 min after which the tourniquet was removed and 0.6 mg/kg rocuronium was administered. Each patient's response to rocuronium injection was graded on a four-point scale in a double-blind manner. Activated coagulation time and plasma potassium concentration were measured before and 5 and 10 min after nafamostat administration.

RESULTS

The incidence of withdrawal response was 68.9% in the control group and 24.4% in the nafamostat group (P < 0.001). The number of patients showing generalized movement (response 4) with the rocuronium injection was significantly lower in nafamostat group [1 (2.2%)] than the control group [15 (33.3%)], P < 0.001. Five and 10 min after nafamostat administration, measured potassium and activated coagulation time were similar to baseline values.

CONCLUSION

Pretreatment with 1.5 mg nafamostat mesilate decreased withdrawal response associated with rocuronium injection.

Peptidase inhibitors in the MEROPS database

The MEROPS website (http://merops.sanger.ac.uk) includes information on peptidase inhibitors as well as on peptidases and their substrates. Displays have been put in place to link peptidases and inhibitors together. The classification of protein peptidase inhibitors is continually being revised, and currently inhibitors are grouped into 67 families based on comparisons of protein sequences. These families can be further grouped into 38 clans based on comparisons of tertiary structure. Small molecule inhibitors are important reagents for peptidase characterization and, with the increasing importance of peptidases as drug targets, they are also important to the pharmaceutical industry. Small molecule inhibitors are now included in MEROPS and over 160 summaries have been written.

Hemoperfusion with a polymyxin B fiber column decreases clotting activity

We investigated whether hemoperfusion with a polymyxin B column (DHP-PMX) was able to improve coagulation abnormalities in patients with sepsis. Sixteen patients with sepsis were enrolled in the study. They all had signs of systemic inflammatory response syndrome due to infection and a mean arterial blood pressure > or =65mm Hg (irrespective of the use of catecholamines). A thermodilution catheter was inserted prior to DHP-PMX for intravenous infusion, and DHP-PMX was performed twice within 24 h for 3 h each time. Circulating levels of thrombin-antithrombin complex (TAT), plasmin-alpha2 plasmin inhibitor complex (PIC), the TAT/PIC ratio, and plasminogen activator inhibitor-1 (PAI-1) were measured six times. Before DHP-PMX, the TAT level was 24.5 +/- 8.3 ng/mL, the PIC level was 2.5 +/- 1.1 microg/mL, the TAT/PIC ratio was 13.9 +/- 3.5, and the PAI-1 level was 143.0 +/- 24.4 ng/L. The TAT level, TAT/PIC ratio, and PAI-1 were all significantly lower (P < 0.05) after 48 hr compared with before DHP-PMX, but no significant change of PIC was observed. In these patients with sepsis, fibrinolysis was inhibited by PAI-1, whereas clotting activity was significantly increased. This coagulation/fibrinolysis imbalance was improved by DHP-PMX. The present results suggest that indirect inhibition of clotting activity can be achieved in patients with sepsis through adsorption of lipopolysaccharide by DHP-PMX.

Human gangliosides and bacterial lipo-oligosaccharides in the development of autoimmune neuropathies

Guillain-Barré syndrome (GBS), the most frequent cause of acute flaccid paralysis, can develop after infection by Campylobacter jejuni. The condition is often associated with serum anti-GM1 or anti-GD1a IgG antibodies. Gangliosides contribute to stability of paranodal junctions and ion channel clusters in myelinated nerve fibers. Autoantibodies to GM1 and GD1a disrupt lipid rafts, paranodal or nodal structures, and ion channel clusters in peripheral motor nerves. Molecular mimicry exists between GM1 and GD1a gangliosides and lipo-oligosaccharides of C. jejuni isolates from GBS patients. Sensitization of rabbits with GM1 or C. jejuni lipo-oligosaccharide produces replica of GBS. These findings provide strong evidence for carbohydrate mimicry being a cause of GBS and show the role of gangliosides in peripheral nerves.

Intense Correlation Between Brain Infarction and Protein-Conjugated Acrolein

Background and Purpose— We recently found that increases in plasma levels of protein-conjugated acrolein and polyamine oxidases, enzymes that produce acrolein, are good markers for stroke. The aim of this study was to determine whether the level of protein-conjugated acrolein is increased and levels of spermine and spermidine, the substrates of acrolein production, are decreased at the locus of infarction.

Methods— A unilateral infarction was induced in mouse brain by photoinduction after injection of Rose Bengal. The volume of the infarction was analyzed using the public domain National Institutes of Health image program. The level of protein-conjugated acrolein at the locus of infarction and in plasma was measured by Western blotting and enzyme-linked immunosorbent assay, respectively. The levels of polyamines at the locus of infarction and in plasma were measured by high-performance liquid chromatography.

Results— The level of protein-conjugated acrolein was greatly increased, and levels of spermine and spermidine were decreased at the locus of infarction at 24 hours after the induction of stroke. The size of infarction was significantly decreased by N -acetylcysteine, a scavenger of acrolein. It was also found that the increases in the protein-conjugated acrolein, polyamines, and polyamine oxidases in plasma were observed after the induction of stroke.

Conclusions— The results indicate that the induction of infarction is well correlated with the increase in protein-conjugated acrolein at the locus of infarction and in plasma.

Nafamostat for Prophylaxis against Post-Endoscopic Retrograde Cholangiopancreatography Pancreatitis Compared with Gabexate

BACKGROUND/AIMS

The protease inhibitors, nafamostat and gabexate, have been used to prevent pancreatitis related to endoscopic retrograde cholangiopancreatography (ERCP). In vitro, nafamostat inhibits the pancreatic protease activities 10-100 times more potently than gabexate. We evaluated the efficacy of nafamostat for prophylaxis against post-ERCP pancreatitis in comparison with gabexate.

METHODS

Five hundred patients (208 patients in the nafamostat-treated group and 292 in the gabexate-treated group) were analyzed retrospectively after selective exclusion. The incidences of pancreatitis and hyperamylasemia after the ERCP were compared between the nafamostat and gabexate groups.

RESULTS

The incidences of acute pancreatitis and hyperamylasemia were 9.1% and 40.9%, respectively, in the nafamostat-treated group, and 8.6% and 39.4% in the gabexate-treated group. The frequencies of post-ERCP pancreatitis and hyperamylasemia did not differ significantly between the two groups, Post-ERCP pancreatitis in two group did not vary according to the different ERCP procedures. The mean serum amylase level at 6 h after ERCP was significantly lower in the nafamostat-treated group than in the gabexate-treated group (p=0.020). However, the difference in serum amylase level did not persist at 18 h and 36 h post-ERCP.

CONCLUSIONS

Administration of nafamostat before ERCP was not inferior to gabexate in protecting against the development of pancreatitis.

Neuronal death in Alzheimer's disease and therapeutic opportunities

Alzheimer’s disease (AD) is an age-related neurodegenerative disease that affects approximately 24 million people worldwide. A number of different risk factors have been implicated in AD; however, neuritic (amyloid) plaques are considered as one of the defining risk factors and pathological hallmarks of the disease. In the past decade, enormous efforts have been devoted to understand the genetics and molecular pathogenesis leading to neuronal death in AD, which has been transferred into extensive experimental approaches aimed at reversing disease progression. Modern medicine is facing an increasing number of treatments available for vascular and neurodegenerative brain diseases, but no causal or neuroprotective treatment has yet been established. Almost all neurological conditions are characterized by progressive neuronal dysfunction, which, regardless of the pathogenetic mechanism, finally leads to neuronal death. The particular emphasis of this review is on risk factors and mechanisms resulting in neuronal loss in AD and current and prospective opportunities for therapeutic interventions. This review discusses these issues with a view to inspiring the development of new agents that could be useful for the treatment of AD.

The complement inhibitor FUT-175 suppresses T cell autoreactivity in experimental autoimmune encephalomyelitis

Several recent studies have shown that interacting antigen presenting cells and/or T cells produced complement activation products C5a and C3a, are integrally involved in T-cell activation, and promote the generation of myelin oligodendrocyte glycoprotein (MOG(35-55))-specific interferon-gamma and interleukin-17-producing T cells in experimental autoimmune encephalomyelitis, a rodent model of multiple sclerosis. In this study, we tested whether FUT-175, a clinical pharmaceutical that has been shown to inhibit the formation of C3/C5 convertases, can attenuate myelin-specific T-cell responses, as well as disease severity in experimental autoimmune encephalomyelitis. In vitro, FUT-175 inhibited local C5a/C3a production by antigen presenting cell-T-cell complexes and attenuated MOG(35-55)-specific Th1 and Th17 responses with little nonspecific cytotoxicity. In vivo administration of FUT-175 delayed experimental autoimmune encephalomyelitis disease onset, lowered clinical scores, decreased central nervous system inflammation, and reduced demyelination. The FUT-175-treated mice exhibited decreased numbers of MOG(35-55)-specific interferon-gamma- and interleukin-17-producing T cells. In addition, results from the FUT-175 treatment of naive recipients of adoptively transferred splenocytes from MOG(35-55)-immunized mice suggested that the effect of FUT-175 was on MOG-specific cellular responses and not on anti-MOG antibodies. These results argue that complement regulators, which inhibit C5a/C3a production, may have therapeutic efficacy in multiple sclerosis and in other clinical conditions in which T cells drive disease pathogenesis.

The mannose-binding lectin pathway is a significant contributor to reperfusion injury in the type 2 diabetic heart

The severity of ischaemic heart disease is markedly enhanced in type 2 diabetes. We recently reported that complement activation exacerbates I/R injury in the type 2 diabetic heart. The purpose of this study was to isolate and examine MBL pathway activation following I/R injury in the diabetic heart. ZLC and ZDF rats underwent 30 minutes of left coronary artery occlusion followed by 120 minutes of reperfusion. Two different groups of ZDF rats were treated with either FUT-175, a broad complement inhibitor, or P2D5, a monoclonal antibody raised against rat MBL-A. ZDF rats treated with FUT175 and P2D5 had significantly decreased myocardial infarct size, C3 deposition and neutrophil accumulation compared with untreated ZDF controls. Taken together, these findings indicate that the MBL pathway plays a key role in the severity of complement-mediated I/R injury in the type 2 diabetic heart.