Cross-enzyme inhibition by gabexate mesylate: formulation and reactivity study

Preventative Effect of Nafamostat Mesilate Infusion into the Main Pancreatic Duct on Post-ERCP Pancreatitis in a Porcine Model: Initial Pilot Study

Background and Aim: Post endoscopic retrograde cholangiopancreatography (post-ERCP) pancreatitis is not an uncommon adverse event but may not be avoidable. Various pharmacological and endoscopic techniques have been used to prevent post-ERCP pancreatitis (PEP), but most have been ineffective. The aim of this study was to evaluate the preventative effect of an intrapancreatic duct injection of nafamostat mesilate (NM) on PEP. Methods: This experimental study was conducted on 8 mini pigs. Animals were randomly allocated to a control group (n = 4) and or a NM group (n = 4). Pancreatitis was induced by infusing contrast medium into the main pancreatic duct by ERCP in all animals. After contrast medium injection, NM (50 mg/5 cc) was infused in the NM group and the same amount of 5% dextrose solution was infused in the control group. Twenty-four hours after endoscopic procedures, pancreatic inflammation, edema, vacuolization, necrosis and hemorrhage were evaluated histologically. Results: All animals survived until the end of the experiment. No peri-procedural technical difficulty or adverse event was encountered. Histologic examinations confirmed acute pancreatitis in all animals. In histologic acute pancreatitis scoring, no significant intergroup differences were observed between edema (P = 0.134), leukocyte infiltration (P = 0.356), vacuolization (P = 1.000), or hemorrhage (P = 0.071) scores. However, mean necrosis score was significantly lower in the NM group (1.0) than in controls (1.75, P = 0.024). Conclusion: NM injection into the intrapancreatic duct produced promising results with respect to the prevention of PEP development, especially regarding the prevention of necrosis.

A novel thermosensitive in-situ gel of gabexate mesilate for treatment of traumatic pancreatitis: An experimental study

Gabexate mesilate (GM) is a trypsin inhibitor, and mainly used for treatment of various acute pancreatitis, including traumatic pancreatitis (TP), edematous pancreatitis, and acute necrotizing pancreatitis. However, due to the characteristics of pharmacokinetics, the clinical application of GM still needs frequently intravenous administration to keep the blood drug concentration, which is difficult to manage. Specially, when the blood supply of pancreas is directly damaged, intravenous administration is difficult to exert the optimum therapy effect. To address it, a novel thermosensitive in-situ gel of gabexate mesilate (GMTI) was developed, and the optimum formulation of GMTI containing 20.6% (w/w) P-407 and 5.79% (w/w) P188 with different concentrations of GM was used as a gelling solvent. The effective drug concentration on trypsin inhibition was examined after treatment with different concentrations of GMTI in vitro, and GM served as a positive control. The security of GMTI was evaluated by hematoxylin-eosin (HE) staining, and its curative effect on grade II pancreas injury was also evaluated by testing amylase (AMS), C-reactive protein (CRP) and trypsinogen activation peptide (TAP), and pathological analysis of the pancreas. The trypsin activity was slightly inhibited at 1.0 and 5.0 mg/mL in GM group and GMTI group, respectively (P<0.05 vs. P-407), and completely inhibited at 10.0 and 20.0 mg/mL (P<0.01 vs. P-407). After local injection of 10 mg/mL GMTI to rat leg muscular tissue, muscle fiber texture was normal, and there were no obvious red blood cells and infiltration of inflammatory cells. Furthermore, the expression of AMS, CRP and TAP was significantly increased in TP group as compared with control group (P<0.01), and significantly decreased in GM group as compared with TP group (P<0.01), and also slightly inhibited after 1.0 and 5.0 mg/mL GMTI treatment as compared with TP group (P<0.05), and significantly inhibited after 10.0 and 20.0 mg/mL GMTI treatment as compared with TP group (P<0.01). HE staining results demonstrated that pancreas cells were uniformly distributed in control group, and they were loosely arranged, partially dissolved, with deeply stained nuclei in TP group. Expectedly, after gradient GMTI treatment, pancreas cells were gradually restored to tight distribution, with slightly stained nuclei. This preliminary study indicated that GMTI could effectively inhibit pancreatic enzymes, and alleviate the severity of trauma-induced pancreatitis, and had a potential drug developing and clinic application value.

Targeting mast cells tryptase in tumor microenvironment: a potential antiangiogenetic strategy

Angiogenesis is a complex process finely regulated by the balance between angiogenesis stimulators and inhibitors. As a result of proangiogenic factors overexpression, it plays a crucial role in cancer development. Although initially mast cells (MCs) role has been defined in hypersensitivity reactions and in immunity, it has been discovered that MCs have a crucial interplay on the regulatory function between inflammatory and tumor cells through the release of classical proangiogenic factors (e.g., vascular endothelial growth factor) and nonclassical proangiogenic mediators granule-associated (mainly tryptase). In fact, in several animal and human malignancies, MCs density is highly correlated with tumor angiogenesis. In particular, tryptase, an agonist of the proteinase-activated receptor-2 (PAR-2), represents one of the most powerful angiogenic mediators released by human MCs after c-Kit receptor activation. This protease, acting on PAR-2 by its proteolytic activity, has angiogenic activity stimulating both human vascular endothelial and tumor cell proliferation in paracrine manner, helping tumor cell invasion and metastasis. Based on literature data it is shown that tryptase may represent a promising target in cancer treatment due to its proangiogenic activity. Here we focused on molecular mechanisms of three tryptase inhibitors (gabexate mesylate, nafamostat mesylate, and tranilast) in order to consider their prospective role in cancer therapy.

Effects of nafamostat mesilate on the prevention of cerulein-induced acute pancreatitis

OBJECTIVES

Protease inhibitors showed protective effects on animal models of acute pancreatitis when administered before induction of pancreatitis, and results when administered after induction are uncertain. We assessed the effects of nafamostat mesilate in a mouse model of cerulein-induced pancreatitis comparing results of before and after induction.

METHODS

Cerulein was injected to mice intraperitoneally to induce pancreatitis, and they received intravenous nafamostat mesilate before and after induction. Serum concentrations of amylase and lipase, histological changes, and tissue expression of myeloperoxidase were measured. In addition, tissue activation of p38 mitogen-activated protein kinase (MAPK) and interleukin-6 was evaluated.

RESULTS

Development of pancreatitis was prevented by pretreatment with nafamostat mesilate. However, such effect was not shown when given after induction, although it partially suppressed myeloperoxidase expression and infiltration of inflammatory cells. Tissue expression of phospho-p38 MAPK was prominent in mice with pancreatitis and suppressed by pretreatment with nafamostat mesilate. Interleukin-6 expression was not influenced by either cerulein or nafamostat mesilate.

CONCLUSIONS

The development of pancreatitis was prevented by treating mice with nafamostat mesilate before induction, however, this finding was not observed if administered after injection of cerulein. Pretreatment with nafamostat mesilate suppressed activation of p38 MAPK.

Non-phospholipid vesicles as carriers for peptides and proteins: Production, characterization and stability studies

In the present study, the preparation, characterization and activity of non-phospholipid vesicles (NPV) containing three aminoacid-based molecules were described. As model compounds trypsin, bovine basic pancreatic inhibitor and polylysine rich peptides derived from the herpes simplex virus type 1 (HSV-1) glycoprotein B were employed. NPV were chosen as alternative to liposomes for the possible administration of aminoacid based molecules via mucous membrane (nasal or vaginal) routes. NPV containing the indicated model drugs have shown to be more stable in term of size with respect to liposomes encapsulating the same model drugs previously produced by our group [Cortesi, R. Argnani, R., Esposito, E., Dalpiaz, A. Scatturin, A., Bortolotti, F., Lufino, M., Guerrini, R., Incorvaia, C., Menegatti, E., Manservigi, R., 2006. Cationic liposomes as potential carriers for ocular administration of peptides with antiherpetic activity. Int. J. Pharm. 317, 90-100]. In addition our study indicates that the produced NPV (i) are able to encapsulate the model drugs over 49%, (ii) are characterized by dimensions compatible with applications on the mucous membrane, (iii) remain stable in size for at least 3 months and (iv) can release the model drug (after a slight lag time) in a controlled fashion as compared to that of the corresponding free solution.

Cationic liposomes as potential carriers for ocular administration of peptides with anti-herpetic activity

In the present study the preparation, characterization and activity of cationic liposomes containing the secretory form of herpes simplex virus type 1 (HSV-1) glycoprotein B (gB1s) or two related polylysine rich peptides, namely DTK1 and DTK2, were described. The immunotherapeutic potential of these HSV antigens containing liposomes was examined with a rabbit ocular model of HSV-1 infection. Our study indicates that the liposomes (i) are able to encapsulate quantitatively gB1s and around 30% the DTK peptides, (ii) are characterized by dimensions compatible with ocular applications and (iii) can release the peptide comparably to the free solution. In addition, neutralization studies demonstrated that an anti-DTK specific polyclonal antiserum can inhibit HSV-1 infection, indicating that such peptides could be a good immunogen/antigen in an anti-HSV vaccine formulation. Although the vaccination protocol did not induce protection against the eye disease, a significative protection against a lethal ocular challenge was detectable together with the absence of reactivation episodes from latency on the survived animals. In this respect, the use of cationic liposomes coupled to gB1s and DTK peptides, as a local ocular vaccine, could represent an interesting approach in order to obtain a possible efficacy in protecting animals against a subsequent HSV-1 ocular challenge.

Modulation of L-arginine transport and nitric oxide production by gabexate mesylate

Gabexate mesylate, a non-antigenic synthetic inhibitor of trypsin-like serine proteinases, is a drug used efficiently in the treatment of pancreatitis and disseminated intravascular coagulation and as a regional anticoagulant for haemodialysis. Considering the structural similarity between L-arginine and gabexate mesylate, the effect of this drug on L-arginine transport, nitric oxide (NO) formation and constitutive NO synthase activity in human platelets was investigated. Data have shown that gabexate mesylate inhibited competitively L-arginine uptake by increasing the K(m) value from 22+/-2 to 86+/-6 microM. The K(i) value was 158 microM at pH 7.4 and 37 degrees. Furthermore, gabexate mesylate decreased dose and time-dependent nitrite and nitrate formation (NO(x) release) and cGMP accumulation in whole cells. In addition, gabexate mesylate inhibited constitutive nitric oxide synthase in a cell-free extract. We concluded that gabexate mesylate could be considered an effective modulator of cellular NO synthesis.

Selective inhibition of human mast cell tryptase by gabexate mesylate, an antiproteinase drug

Gabexate mesylate is a non-antigenic synthetic inhibitor of trypsin-like serine proteinases that is therapeutically used in the treatment of pancreatitis and disseminated intravascular coagulation and as a regional anticoagulant for hemodialysis. Considering the structural similarity between gabexate mesylate and arginine-based inhibitors of trypsin-like serine proteinases, the effect of gabexate mesylate on human and bovine mast cell tryptase action was investigated. Values of the inhibition constant (K(i)) for gabexate mesylate binding to human and bovine tryptase were 3.4 x 10(-9) M and 1.8 x 10(-7) M (at pH 7.4 and 37.0 degrees ), respectively. Furthermore, gabexate mesylate inhibited the fibrinogenolytic activity of human tryptase. On the basis of the available x-ray crystal structure of human tryptase, the possible binding mode of gabexate mesylate to human and bovine tryptase was analyzed. Human tryptase inhibition by gabexate mesylate may account for the reported prevention of inflammation, erosion, and ulceration of skin and mucosae.

Inhibition of pig liver and Zea mays L. polyamine oxidase: a comparative study

Polyamine oxidase (PAO) is involved in polyamine metabolism and production of hydrogen peroxide in animal and plants, thus representing a key system in development and programmed cell death. In the present study, the inhibitory effect of amiloride, p-aminobenzamidine, clonidine, 4',6-diamidino-2-phenyl-indole (DAPI), gabexate mesylate, guazatine, and N,N'-bis(2,3-butadienyl)-1,4-butane-diamine (MDL72527) on the catalytic activity of pig liver and Zea mays L. PAO, Lens culinaris L. and Pisum sativum L. and swine kidney copper amine oxidase, bovine trypsin, as well as neuronal constitutive nitric oxide synthase (NOS-I) was investigated. Moreover, agmatine and N(3) -prenylagmatine (G3) were observed to inhibit pig liver and Zea mays L. PAO, bovine trypsin, and NOS-I action, but were substrates for Lens culinaris L., Pisum sativum L. and swine kidney copper amine oxidase. Guazatine and G3 inhibited selectively Zea mays L. PAO with K(i) values of 7.5 x 10(-9) M and 1.5 x 10(-8) M, respectively (at pH 6.5 and 25.0 degrees C). As a whole, the data reported here represent examples of enzyme cross-inhibition, and appear to be relevant in view of the use of cationic L-arginine-and imidazole-based compounds as drugs.