Open Label, Pilot Evaluation of the Safety and Efficacy of Intravesical Sustained Release System of Lidocaine and Oxybutynin (TRG-100) for Patients With Interstitial Cystitis/Bladder Pain Syndrome, Overactive Bladder and Patients With Retained Ureteral Stents Following Endourological Interventions.

BACKGROUND: Intravesical instillation of analgesic and anticholinergic drugs have shown efficacy in the treatment of pain and voiding symptoms. Unfortunately, drug loss with urination and dilution in the bladder limit their durability and clinical usefulness. We have recently developed and tested in vitro, a sustained delivery system (TRG-100) of fixed-dose combination of lidocaine and oxybutynin designed to allow for a longer exposure of the urinary bladder to the drugs. OBJECTIVE: To asses the safety and efficacy of TRG-100 in Interstitial Cystitis/Bladder Pain Syndrome (IC/BPS), overactive bladder (OAB), and endourological intervention stented (EUI) patients in an open-label, prospective study. METHODS: Thirty-six patients were enrolled: 10 IC/BPS, 10 OAB, and 16 EUI. EUI patients received a once-weekly installation until stent removal, OAB and IC/BPS patient received weekly installations for 4 consecutive weeks. Treatment effect was assessed by visual analog scale (VAS) score for the EUI group, voiding diaries for OAB group and VAS score, voiding diaries and O'Leary Sant Questionnaires for the IC/BPS group. RESULTS: The EUI group showed a mean 4-point improvement in their VAS score. The OAB group showed 33.54% reduction in frequency of urination and IC/PBS group showed a mean of 3.2-point improvement in their VAS score, 25.43% reduction in frequency of urination, and a mean 8.1-point reduction in O'Leary Sant Questionnaires score. All changes were statistically significant. CONCLUSION: Intravesical instillation of TRG-100 was found to be safe and efficient in reducing pain and irritative bladder symptoms in our study population. TRG-100 efficacy and safety should be further assessed in a large, randomized control trial.

Effect of cyclosporine A - tempol topical gel for the treatment of alopecia and anti-inflammatory disorders.

Over the years, extensive research has been carried out to develop new chemical entities for hair loss treatment. Despite these efforts, the newly developed topical and oral treatments have not proven to be curative. Hair loss can result from underlying mechanisms, such as inflammation and apoptosis around hair follicles. We have developed a nanoemulsion based on Pemulen gel for topical application, tentatively addressing both mechanisms. The novel formulation contains two well-known molecules: Cyclosporin A (CsA), an immunosuppressant calcineurin inhibitor, and Tempol, a potent antioxidant. The in vitro permeation study on human skin revealed that the CsA-Tempol gel formulation effectively delivered CsA into the skin's inner target layer, the dermis. The effects of the CsA-Tempol gel on hair regrowth were further demonstrated in the in vivo well-established androgenetic model induced in female C57BL/6 mice. The beneficial outcome was statistically confirmed by quantitative analysis of hair regrowth, measured by color density. The results were further supported by histology analysis. Our findings revealed a topical synergy effect, resulting in lower therapeutic concentrations of both actives unlikely to cause systemic side effects. Overall, our research suggests that the CsA-Tempol gel is a highly promising platform for treating alopecia.

The dose-dependent effect of a stabilized cannabidiol nanoemulsion on ocular surface inflammation and intraocular pressure.

Cannabidiol (CBD) is a phytocannabinoid that has a great clinical therapeutic potential. Few studies have been published on its efficacy in ocular inflammations while its impact on intraocular pressure (IOP), a major risk factor for glaucoma, remains unclear. Moreover, due to its lability and high lipophilicity, its formulation within a prolonged stable topical ophthalmic solution or emulsion able to penetrate the highly selective corneal barrier is challenging. Therefore, various CBD nanoemulsions (NEs) were designed and evaluated for stability in accelerated conditions. Further, the optimal formulation was tested on a murine LPS-induced keratitis inflammation model. Lastly, increasing CBD concentrations were topically applied, for two weeks, on mice eyes, for IOP measurement. CBD NEs exhibited optimal physicochemical characteristics for ocular delivery. A specific antioxidant was required to obtain the stable, final, formulation. In vivo, 0.4 to 1.6% CBD w/v reduced the levels of key inflammatory cytokines, depending on the concentration applied. These concentrations decreased or did not affect the IOP. Our results showed that a well-designed CBD ocular dosage form can be stabilized for an extended shelf life. Furthermore, the significant decrease in inflammatory cytokines levels could be exploited, provided that an adequate therapeutic dosage regimen is identified in humans.

Biodistribution and efficacy of the anticancer drug, oxaliplatin palmitate acetate, in mice.

Oxaliplatin palmitate acetate (OPA), a platinum (IV) oxaliplatin derivative, was previously designed with the aim to improve the platinum-based anti-cancer therapy. In this work, we further explore the potential of OPA in extensive in vitro and in vivo studies. OPA in pancreatic (BxPC3-luc), lung (NCI-H1993) and liver (Hep3B) cancer cell lines showed a higher toxicity in comparison to oxaliplatin. The in vitro release kinetic experiments of OPA from the nanoparticles (NPs) under sink conditions exhibited a very rapid profile. Furthermore, OPA cannot be considered a prodrug of oxaliplatin, based on the OPA intact molecule pharmacokinetic profile study in rats. The formation of oxaliplatin from the biodegradation of OPA ranges only from 5% to 7% and both drugs were rapidly eliminated from the plasma. Pharmacokinetics of OPA PLGA nanoparticles in mice showed that nanoparticles failed to prolong the release of OPA in the plasma and did not add any therapeutic benefit over OPA solution, as suggested by the rapid in vitro release of OPA from nanoparticles. In pancreatic xenograft BxPC3-luc cancer model, both OPA in solution and OPA nanoparticles inhibited the tumor growth, equally and significantly, as compared to oxaliplatin. In liver xenograft Hep3B cancer model, OPA solution and cisplatin demonstrated good and similar antitumor efficacy. In lung xenograft NCI-H1993 cancer model, OPA solution, with a significant antitumor efficacy, was superior to cisplatin, which did not differ from the vehicle. In conclusion, OPA may offer a promising advance in platinum-based chemotherapy against various forms of cancers in an adequate dose and schedule.

Topical tacrolimus nanocapsules eye drops for therapeutic effect enhancement in both anterior and posterior ocular inflammation models.

Tacrolimus has shown efficacy in eye inflammatory diseases. However, due to the drug lability, its formulation into a stable ophthalmic product remains a challenge. Tacrolimus-loaded nanocapsules (NCs) were designed for ocular instillation. Further, the stability and effects of the formulation were analyzed under different experimental conditions. Physicochemical characterization of the NCs revealed suitable homogeneous size and high encapsulation efficiency. Moreover, the lyophilized formulation was stable at ICH long term and accelerated storage conditions, for at least 18 and 3 months, respectively. The tacrolimus NCs did not elicit any eye irritation in rabbits after single- and multiple-dose applications. Additionally, ex vivo penetration assays on isolated porcine cornea and pharmacokinetics analyses in various rabbit eye compartments demonstrated the superiority of the NCs in retention and permeation into the anterior chamber of the eye compared to the free drug dissolved in oil. Moreover, multiple dose ocular instillation of the NCs in rats allowed high tacrolimus levels in the eye with very low plasma concentrations. Finally, the developed delivery system achieved a significant decrease in four typical inflammatory markers in a murine model of keratitis, an anterior chamber inflammation. Furthermore, these NCs, applied as eye drops, displayed clinical and histological efficacy in the mainly posterior chamber inflammation model of murine, experimental auto-immune uveitis.

Novel targeted mtLivin nanoparticles treatment for disseminated diffuse large B-cell lymphoma.

We previously showed that Livin, an inhibitor of apoptosis protein, is specifically cleaved to produce a truncated protein, tLivin, and demonstrated its paradoxical proapoptotic activity. We further demonstrated that mini-tLivin (MTV), a 70 amino acids derivative of tLivin, is a proapoptotic protein as potent as tLivin. Based on these findings, in this study we aimed to develop a venue to target MTV for the treatment of diffuse large B-cell lymphoma (DLBCL). MTV was conjugated to poly (lactide-co-glycolic acid) surface-activated nanoparticles (NPs). In order to target MTV-NPs we also conjugated CD40 ligand (CD40L) to the surface of the NPs and evaluated the efficacy of the bifunctional CD40L-MTV-NPs. In vitro, CD40L-MTV-NPs elicited significant apoptosis of DLBCL cells. In a disseminated mouse model of DLBCL, 37.5% of MTV-NPs treated mice survived at the end of the experiment. Targeting MTV-NPs using CD40L greatly improved survival and 71.4% of these mice survived. CD40L-MTV-NPs also greatly reduced CNS involvement of DLBCL. Only 20% of these mice presented infiltration of lymphoma to the brain in comparison to 77% of the MTV-NPs treated mice. In a subcutaneous mouse model, CD40L-MTV-NPs significantly reduced tumor volume in correlation with significant increased caspase-3 activity. Thus, targeted MTV-NPs suggest a novel approach to overcome apoptosis resistance in cancer.

Topical nano-encapsulated cyclosporine formulation for atopic dermatitis treatment.

Systemic cyclosporine A (CsA) therapy shows efficacy in the treatment of recalcitrant severe atopic dermatitis (AD) but elicits severe side-effects. Thus, a topical formulation of CsA nanocapsules (NCs), able to potentially bypass these drawbacks, was developed. CsA-NCs were shown to enhance drug penetration into the various layers of porcine ear skin. Furthermore, the encapsulated CsA was biologically active, as shown in vitro on mouse splenocytes, reflected by inhibition of both cell proliferation and of interleukin (IL)-2 secretion. Ex-vivo efficacy was demonstrated on human skin organ culture by markedly reducing pro-inflammatory cytokines secretion. Finally, CsA-NCs topical formulation elicited improved efficacy in terms of better preservation of the skin barrier integrity, a decrease of the systemic pro-inflammation markers and reduced skin inflammation. The overall results suggest that this original topical platform may provide a novel therapeutic tool of clinical significance compared to the existing topical therapeutic drugs in AD.

Nanocapsules embedded in microparticles for enhanced oral bioavailability and efficacy of Lopinavir as an anti-AIDS drug.

Lopinavir (LPV), an efficient drug for HIV infection treatment, was incorporated into biodegradable PLGA nanocapsules (NCs) embedded in microparticles (MCPs) using the spray-drying technique in an attempt to bypass the P-gp efflux and protect the drug from CYP3A pre-systemic metabolism without ritonavir (RTV). SEM observations confirmed the formation of NCs and their entrapment in the MCPs. LPV-loaded NCs and free LPV were released from the MCPs at pH of 7.4 as evidenced by in vitro release studies. Results obtained from rat studies showed a two-fold higher bioavailability of LPV following oral administration of the optimal formulation than Kaletra®, the marketed drug, showing that when properly entrapped, LPV can be effectively protected from CYP degradation in the gut as well as from the liver following systemic absorption. It was also shown that serum derived from rats following LPV oral administration in two formulations and Kaletra® significantly decreased the multiplication of HIV-1 in cultured SupT1 cells. Furthermore, the LPV formulations markedly restricted the titre of infectious HIV-1 production compared with Kaletra® confirming the improved antiviral activity of LPV delivered in the rat blood circulation by the nanocapsules embedded in microparticle formulations.

Pharmacodynamical effects of orally administered exenatide nanoparticles embedded in gastro-resistant microparticles.

One of the major disadvantages associated with macromolecules therapy is that most of them can only be administered parenterally. Exenatide, an efficient anti-diabetic drug, incretin mimetic, is currently administered subcutaneously (SC) causing compliance issues. Nanoparticles (NPs) are considered a promising solution for oral delivery of this drug. In order to overcome exenatide's inability to cross the enterocytes and to increase its stability in the gastrointestinal (GI) tract, we encapsulated exenatide into a nano-in-micro delivery system. This drug delivery system (DDS) improved the relative oral bioavailability of exenatide, in comparison to Byetta® injection SC. In this study, we report about the efficacy of this DDS to improve glycemic parameters in diabetic ob/ob mice. Our results suggested that our DDS successfully lowered blood glucose levels (BGL) raised insulin levels, decreased glycated hemoglobin and maintained the body weight of the mice. These findings validate the efficacy of this DDS in promoting oral delivery of exenatide and will hopefully improve patient compliance and adherence. The potential of this DDS to encapsulate other leading peptides and proteins, such as insulin, was also evaluated in this study. It was found that peptides up to 6 kDa can be efficiently encapsulated, but the in-vivo performance is also dependent on other physicochemical properties.

Solid nano-in-nanoparticles for potential delivery of siRNA.

siRNA-based therapeutics possess great potential to treat a wide variety of genetic disorders. However, they suffer from low cellular uptake and short half-lives in blood circulation; issues that remain to be addressed. This work is, to the best of our knowledge, the first to report the production of solid nano-in-nanoparticles, termed double nano carriers (DNCs) by means of the innovative technology of nano spray drying. DNCs (with a median size of 580-770nm) were produced by spraying at low temperatures (50°C) to prevent damage to heat-sensitive biomacromolecules like siRNA. DNCs consisting of Poly (d,l-lactide-co-glycolide) used as a wall material, encapsulating 20% human serum albumin primary nanoparticles (PNPs) loaded with siRNA, were obtained as a dry nanoparticulate powder with smooth spherical surfaces and a unique inner morphology. Incubation of pegylated or non-pegylated DNCs under sink conditions at 37°C, elicited a controlled release profile of the siRNA for up to 12 or 24h, respectively, with a minimal burst effect. Prolonged incubation of pegylated DNCs loaded with active siRNA (anti EGFR) in an A549 epithelial cell culture monolayer did not induce any apparent cytotoxicity. A slow degradation of the internalized DNCs by the cells was also observed resulting in the progressive release of the siRNA for up to 6days, as corroborated by laser confocal microscopy. The structural integrity and silencing activity of the double encapsulated siRNA were fully preserved, as demonstrated by HPLC, gel electrophoresis, and potent RNAi activity of siRNA extracted from DNCs. These results demonstrate the potential use of DNCs as a nano drug delivery system for systemic administration and controlled release of siRNA and potentially other sensitive bioactive macromolecules.

A Lipophilic Pt(IV) Oxaliplatin Derivative Enhances Antitumor Activity.

Side effects and acquired resistance by cancer cells limit the use of platinum anticancer drugs. Modification of oxaliplatin (OXA) into a lipophilic Pt(IV) complex [Pt(DACH)(OAc)(OPal)(ox)] (1), containing both lipophilic and hydrophilic axial ligands, was applied to improve performance and facilitate incorporation into polymeric nanoparticles. Complex 1 exhibited unique potency against a panel of cancer cells, including cisplatin-resistant tumor cells. [Pt(DACH)(OAc)(OPal)(ox)] incorporated nanoparticles (2) presented a mean diameter of 146 nm with encapsulation yields above 95% as determined by HPLC. Complexes 1 and 2 showed enhanced in vitro cellular Pt accumulation, DNA platination, and antiproliferative effect compared to OXA. Results of an orthotopic intraperitoneal model of metastatic ovarian cancer (SKOV-3) and a xenograft subcutaneous model of colon (HCT-116) tumor in SCID-bg mice showed that the activity of 1 and 2 significantly decreased tumor growth rates compared to control and OXA treatment groups. Consequently, these findings warrant further development toward clinical translation.

Kinetic characterization and regulation of the human retinaldehyde dehydrogenase 2 enzyme during production of retinoic acid.

Retinoic acid (RA) is an important regulator of embryogenesis and tissue homoeostasis. Perturbation of RA signalling causes developmental disorders, osteoarthritis, schizophrenia and several types of tumours. RA is produced by oxidation of retinaldehyde from vitamin A. The main enzyme producing RA in the early embryo is retinaldehyde dehydrogenase 2 (RALDH2, ALDH1A2). In the present study we describe in depth the kinetic properties and regulation of the human RALDH2 (hRALDH2) enzyme. We show that this enzyme produces RA using in vivo and in vitro assays. We studied the naturally occurring all-trans-, 9-cis- and 13-cis-retinaldehyde isomers as substrates of hRALDH2. Based on the values measured for the Michaelis-Menten constant Km and the maximal rate Vmax, in vitro hRALDH2 displays the same catalytic efficiency for their oxidation. We characterized two known inhibitors of the vertebrate RALDH2 and determined their kinetic parameters on hRALDH2. In addition, RA was studied as a possible inhibitor of hRALDH2 and a regulator of its activity. We show that hRALDH2 is not inhibited by its oxidation product, all-trans-RA, suggesting the absence of a negative feedback regulatory loop. Expression of the Raldh2 gene is known to be regulated by RA itself, suggesting that the main regulation of the hRALDH2 activity level is transcriptional.

Improved oral absorption of exenatide using an original nanoencapsulation and microencapsulation approach.

Oral delivery is the most convenient and favorable route for chronic administration of peptides and proteins to patients. However, many obstacles are faced when developing such a delivery route. Nanoparticles (NPs) are among the leading innovative solutions for delivery of these drugs. Exenatide is a peptidic drug administered subcutaneously (SC) twice a day chronically as an add-on therapy for the worldwide pandemic disease, diabetes. Many attempts to develop oral nanocarriers for this drug have been unsuccessful due to the inability to retain this hydrophilic macromolecule under sink conditions or to find a suitable cross-linker which does not harm the chemical integrity of the peptide. In this study, we report about an original oral delivery solution based on a mixture of albumin and dextran NPs cross-linked using sodium trimetaphosphate (STMP). Moreover, we suggest a second defense line of gastro-resistant microparticles (MPs) composed of an appropriate ratio of Eudragit® L100-55 (Eudragit L) and hydroxypropylmethylcellulose (HPMC), for additional protection to these NPs presumably allowing them to be absorbed in the intestine intact. Our results demonstrate that such a system indeed improves the relative oral bioavailability of exenatide to a level of about 77% compared to subcutaneous injection due to the presence of dextran in the coating wall of the NPs which apparently promotes the lymphatic uptake in the enterocytes. This technology may be a milestone on the way to deliver other peptides and proteins orally.

Oral delivery system prolongs blood circulation of docetaxel nanocapsules via lymphatic absorption.

An original oral formulation of docetaxel nanocapsules (NCs) embedded in microparticles elicited in rats a higher bioavailability compared with the i.v. administration of the commercial docetaxel solution, Taxotere. In the present study, various animal studies were designed to elucidate the absorption process of docetaxel from such a delivery system. Again, the docetaxel NC formulation elicited a marked enhanced absorption compared with oral Taxotere in minipigs, resulting in relative bioavailability and Cmax values 10- and 8.4-fold higher, respectively, confirming the previous rat study results. It was revealed that orally absorbed NCs altered the elimination and distribution of docetaxel, as shown in the organ biodistribution rat study, due to their reinforced coating, while transiting through the enterocytes by surface adsorption of apoproteins and phospholipids. These findings were demonstrated by the cryogenic-temperature transmission electron microscopy results and confirmed by the use of a chylomicron flow blocker, cycloheximide, that prevented the oral absorption of docetaxel from the NC formulation in an independent pharmacokinetic study. The lipoproteinated NCs reduced the docetaxel release in plasma and its distribution among the organs. The improved anticancer activity compared with i.v. Taxotere, observed in the metastatic lung cancer model in Severe Combined Immune Deficiency-beige (SCID-bg) mice, should be attributed to the extravasation effect, leading to the lipoproteinated NC accumulation in lung tumors, where they exert a significant therapeutic action. To the best of our knowledge, no study has reported that the absorption of NCs was mediated by a lymphatic process and reinforced during their transit.

Antibody conjugated PLGA nanoparticles for targeted delivery of paclitaxel palmitate: efficacy and biofate in a lung cancer mouse model.

Aberrant signaling of the epidermal growth factor receptor (EGFR) is common to a variety of human cancers and is also found to be over-expressed in most cases of non-small cell lung cancer. For the development of a molecularly targeted therapy, cetuximab-conjugated nanoparticles (immunonanoparticles, INPs) are designed and loaded with the lipophilic paclitaxel palmitate (pcpl) prodrug. Oleyl cysteineamide (OCA) is synthesized whereby its amphiphilic nature enables interfacial anchoring and thiol surface functionalization of PLGA NPs, facilitating bioconjugation to cetuximab by thioether bonds. It is demonstrated that the in vitro targeting efficiency and improved cellular internalization and cytotoxicity of this targeted delivery system in lung cancer cells over-expressing EGFR. A quantitative measure of the high binding affinity of INPs to EGFR is demonstrated using surface plasmon resonance. In vivo tolerability and enhanced efficacy of cetuximab pcpl INPs in a metastatic lung cancer model are reported. Its therapeutic efficacy in A549-luc-C8 lung tumors is shown using non-invasive bioluminescent imaging. Intravenous administration of cetuximab pcpl INPs to mice results in significantly higher inhibition of tumor growth and increased survival rates as compared to the non-targeted drug solution, drug-loaded nanoparticles or blank INPs. Pharmacokinetics and organ biodistribution of the prodrug and parent drug are evaluated by LC-MS/MS in lung tumor bearing mice. No enhanced total accumulation of nanoparticles or INPs is found at the tumor tissue. However, persistent pcpl levels with sustained conversion and release of paclitaxel are observed for the encapsulated prodrug possibly suggesting the formation of a drug reservoir. The overall results indicate the potential of this promising targeted platform for the improved treatment of lung cancer and other EGFR positive tumors.

Safety and proof-of-concept efficacy of inhaled drug loaded nano- and immunonanoparticles in a c-Raf transgenic lung cancer model.

Pulmonary delivery of drug-loaded nanoparticles is a novel approach for lung cancer treatment and the conjugation of nanoparticles to a targeting ligand further promotes specificity of the carrier cargo to cancer cells. Notably, the epithelial cell adhesion molecule (EpCAM, CD326) is over expressed in lung cancer. Here, we report the safety and proof-of-concept efficacy of drug-loaded nanoparticles and EpCAM immunonanoparticles in a c-Raf transgenic lung cancer model. PEG-PLA nanoparticles and immunonanoparticles were prepared whereby paclitaxel palmitate (Pcpl) was incorporated as a medication for its common use in lung cancer treatment. Four doses of aerosolized nanoparticle formulations or vehicle were endotracheally administered to mice by consecutive or alternate regimes. Pulmonary delivery of drug loaded nano- and/or immunonanoparticle formulations elicited mild inflammation as evidenced by the slightly increased neutrophil and activated macrophage counts in bronchoalveolar lavage. No evidence for pulmonary toxicity following treatment with either blank or drug-loaded nano- and/or immunonanoparticles was observed. Proof-of-concept efficacy was determined by serial CT scanning and histopathology. Animals treated with either EpCAM antibody or Pcpl solution or drug loaded nano- or immunonanoparticles inhibited disease progression. Conversely, disease progression was noted with vehicle treated animals with nearly 30% loss of their aerated lung volume. Importantly, treatment of mice with either Pcpl or EpCAM antibody solution caused 80% mortality and/or haemorrhage, respectively, thus causing unacceptable toxicity. In contrast, the survival of animals treated with either nano- or immunonanoparticles was 60 and 70%, respectively. Taken collectively, pulmonary delivered drug-loaded nano- and EpCAM immunonanoparticles were well tolerated and can be considered a promising strategy for improving lung cancer treatment.

Insulin and glucagon share the same mechanism of neuroprotection in diabetic rats: role of glutamate.

In patients with acute ischemic stroke, diabetes and hyperglycemia are associated with increased infarct size, more profound neurologic deficits and higher mortality. Notwithstanding extensive clinical and experimental data, treatment of stroke-associated hyperglycemia with insulin is controversial. In addition to hyperglycemia, diabetes and even early prediabetic insulin resistance are associated with increased levels of amino acids, including the neurotoxic glutamate, in the circulation. The pleiotropic metabolic effects of insulin include a reduction in the concentration of amino acids in the circulation. In this article, we show that in diabetic rats exposed to transient middle cerebral artery occlusion, a decrease of plasma glutamate by insulin or glucagon reduces CSF glutamate, improves brain histology, and preserves neurologic function. The neuroprotective effect of insulin and glucagon was similar, notwithstanding their opposite effects on blood glucose. The therapeutic window of both hormones overlapped with the short duration (~30 min) of elevated brain glutamate following brain trauma in rodents. Similar neuroprotective effects were found after administration of the glutamate scavenger oxaloacetate, which does not affect glucose metabolism. These data indicate that insulin and glucagon exert a neuroprotective effect within a very brief therapeutic window that correlates with their capacity to reduce glutamate, rather than by modifying glucose levels.

tPA regulates pulmonary vascular activity through NMDA receptors.

Tissue-type plasminogen activator (tPA) is a potent fibrinolytic enzyme used to treat acute coronary artery obstruction. However, tPA has shown limited utility in other disorders caused by thrombotic vascular occlusion, such as pulmonary embolism. We found that tPA caused dose-dependent effects on the contractility of pulmonary arterial rings that may affect its effectiveness as a thrombolytic agent. At low concentrations (1 nM), tPA stimulated pulmonary vascular contraction in response to phenylephrine, whereas at higher concentrations (20 nM) tPA inhibited pulmonary arterial contractility and promoted pulmonary vascular permeability through an interaction between its "docking site" and N-methyl d-aspartate receptor type 1 (NMDA-R1) expressed by pulmonary arteries. A hexapeptide derived from plasminogen activator inhibitor type 1 that blocked the docking site of tPA, but not its catalytic activity, inhibited its interaction with NMDA-R1, abolished inhibition of pulmonary artery contractility, attenuated vascular permeability, and facilitated fibrinolysis in a murine model of pulmonary embolism. Similar outcomes were seen using a tPA variant that lacks the docking site but retains catalytic activity. These data suggest that it is feasible to attenuate the deleterious extrafibrinolytic effects of tPA and improve its benefit:risk profile in the management of pulmonary embolism.

Urokinase plasminogen activator regulates pulmonary arterial contractility and vascular permeability in mice.

The concentration of urokinase plasminogen activator (uPA) is elevated in pathological settings such as acute lung injury, where pulmonary arterial contractility and permeability are disrupted. uPA limits the accretion of fibrin after injury. Here we investigated whether uPA also regulates pulmonary arterial contractility and permeability. Contractility was measured using isolated pulmonary arterial rings. Pulmonary blood flow was measured in vivo by Doppler and pulmonary vascular permeability, according to the extravasation of Evans blue. Our data show that uPA regulates the in vitro pulmonary arterial contractility induced by phenylephrine in a dose-dependent manner through two receptor-dependent pathways, and regulates vascular contractility and permeability in vivo. Physiological concentrations of uPA (≤1 nM) stimulate the contractility of pulmonary arterial rings induced by phenylephrine through the low-density lipoprotein receptor-related protein receptor. The procontractile effect of uPA is independent of its catalytic activity. At pathophysiological concentrations, uPA (20 nM) inhibits contractility and increases vascular permeability. The inhibition of vascular contractility and increase of vascular permeability is mediated through a two-step process that involves docking to N-methyl-d-aspartate receptor-1 (NMDA-R1) on pulmonary vascular smooth muscle cells, and requires catalytic activity. Peptides that specifically inhibit the docking of uPA to NMDA-R, or the uPA variant with a mutated receptor docking site, abolished both the effects of uPA on vascular contractility and permeability, without affecting its catalytic activity. These data show that uPA, at concentrations found under pathological conditions, reduces pulmonary arterial contractility and increases permeability though the activation of NMDA-R1. The selective inhibition of NMDAR-1 activation by uPA can be accomplished without a loss of fibrinolytic activity.

Urokinase-type plasminogen activator (uPA) induces pulmonary microvascular endothelial permeability through low density lipoprotein receptor-related protein (LRP)-dependent activation of endothelial nitric-oxide synthase.

Urokinase plasminogen activator (uPA) and PA inhibitor type 1 (PAI-1) are elevated in acute lung injury, which is characterized by a loss of endothelial barrier function and the development of pulmonary edema. Two-chain uPA and uPA-PAI-1 complexes (1-20 nM) increased the permeability of monolayers of human pulmonary microvascular endothelial cells (PMVECs) in vitro and lung permeability in vivo. The effects of uPA-PAI-1 were abrogated by the nitric-oxide synthase (NOS) inhibitor L-NAME (N(D)-nitro-L-arginine methyl ester). Two-chain uPA (1-20 nM) and uPA-PAI-1 induced phosphorylation of endothelial NOS-Ser(1177) in PMVECs, which was followed by generation of NO and the nitrosylation and dissociation of ß-catenin from VE-cadherin. uPA-induced phosphorylation of eNOS was decreased by anti-low density lipoprotein receptor-related protein-1 (LRP) antibody and an LRP antagonist, receptor-associated protein (RAP), and when binding to the uPA receptor was blocked by the isolated growth factor-like domain of uPA. uPA-induced phosphorylation of eNOS was also inhibited by the protein kinase A (PKA) inhibitor, myristoylated PKI, but was not dependent on PI3K-Akt signaling. LRP blockade and inhibition of PKA prevented uPA- and uPA-PAI-1-induced permeability of PMVEC monolayers in vitro and uPA-induced lung permeability in vivo. These studies identify a novel pathway involved in regulating PMVEC permeability and suggest the utility of uPA-based approaches that attenuate untoward permeability following acute lung injury while preserving its salutary effects on fibrinolysis and airway remodeling.