Botulinum and Tetanus Neurotoxins.

Botulinum neurotoxins (BoNTs) and tetanus neurotoxin (TeNT) are the most potent toxins known and cause botulism and tetanus, respectively. BoNTs are also widely utilized as therapeutic toxins. They contain three functional domains responsible for receptor-binding, membrane translocation, and proteolytic cleavage of host proteins required for synaptic vesicle exocytosis. These toxins also have distinct features: BoNTs exist within a progenitor toxin complex (PTC), which protects the toxin and facilitates its absorption in the gastrointestinal tract, whereas TeNT is uniquely transported retrogradely within motor neurons. Our increasing knowledge of these toxins has allowed the development of engineered toxins for medical uses. The discovery of new BoNTs and BoNT-like proteins provides additional tools to understand the evolution of the toxins and to engineer toxin-based therapeutics. This review summarizes the progress on our understanding of BoNTs and TeNT, focusing on the PTC, receptor recognition, new BoNT-like toxins, and therapeutic toxin engineering.

Hidden Potential of Highly Efficient and Widely Accessible Thrombolytic Staphylokinase.

Stroke burden is substantially increasing but current therapeutic drugs are still far from ideal. Here we highlight the vast potential of staphylokinase as an efficient, fibrin-selective, inexpensive, and evolvable thrombolytic agent. The emphasis is escalated by new recent findings. Staphylokinase nonimmunogenic variant was proven noninferior to alteplase in a clinical trial, with decreased risk of intracranial hemorrhage and the advantage of single bolus administration. Furthermore, our detailed kinetic analysis revealed a new staphylokinase limiting bottleneck whose elimination might provide up to 1000-fold higher activity than the clinically approved alteplase. This knowledge of limitations unlocks new possibilities for improvements that are now achievable by the community of protein engineers who have the required expertise and are ready to transform staphylokinase into a powerful molecule. Collectively, the noninferiority and safety of nonimmunogenic staphylokinase together with the newly identified effectivity limitation make staphylokinase a perfect candidate for further exploration, modification, and advancement to make it the next-generation widely accessible thrombolytic drug effectively treating stroke all around the world, including middle- and low-income countries.

Treatment with a Zinc Metalloprotease Purified from Bothrops moojeni Snake Venom (BmooMP-Alpha-I) Reduces the Inflammation in an Experimental Model of Dextran Sulfate Sodium-Induced Colitis.

It has been described that the metalloprotease BmooMP-alpha-I purified from Bothrops moojeni snake venom is able to hydrolyze the TNF molecule. However, this observation has been based mainly on in vitro investigation, in addition to molecular modeling and docking approaches. Considering that there is no in vivo study to demonstrate the biological effects of this enzyme, the major aim to the present work was to investigate whether the BmooMP-alpha-I has any anti-inflammatory efficacy by setting up a murine experimental design of colitis induced by dextran sulfate sodium (DSS). For this purpose, C57BL/6 mice were divided into six groups, as follows: (i) animals without intestinal inflammation, (ii) animals without intestinal inflammation treated with BmooMP-alpha-I (50 µg/animal/day), and (iii) animals with intestinal inflammation induced by 3% of DSS, (iv) mice with intestinal inflammation induced by DSS and treated with BmooMP-alpha-I enzyme at the 50, 25, or 12.5 µg/animal/day dosages by intraperitoneal route. Clinical signs of colitis were observed daily for calculating the morbidity scores, cytokine measurements, and histological features. We observed that the animals treated with different doses of the enzyme presented a remarkable improvement of colitis signs, as confirmed by a significant increase of the intestine length in comparison to the DSS group. Also, no difference was observed between the groups treated with the enzyme or vehicle, as the colon length of these animals was slightly lower than that of the group of healthy animals, without induction of intestinal inflammation. The cytokine quantification in supernatants of intestinal tissue homogenates showed a significant reduction of 38% in IFN-gamma levels, when the animals were treated with 50 µg of the BmooMP-alpha-I compared to the animals receiving DSS only. A significant reduction of 39% in TNF levels was also observed in all doses of treatment with BmooMP-alpha-I, in addition to a significant reduction of 35% in the amount of IL-12p40. Histological examinations revealed that the BmooMP-alpha-I 50 µg treated group preserved colon architecture and goblet cells and reduced the ulcer area, when compared with DSS mice, which showed typical inflammatory changes in tissue architecture, such as ulceration, crypt dilation, loss of tissue architecture, and goblet cell depletion, accompanied by a significant cell infiltration. In conclusion, our results suggest that the improvement of clinical scores and histological findings related to BmooMP-alpha-I treatment in this experimental model could be attributed to the metalloprotease ability to modulate cytokine production locally at the inflamed intestine. These findings highlight the potential anti-inflammatory role and effectiveness of this enzyme as a therapeutic alternative in this type of immunopathological condition.

Antiproliferative effect of the jararhagin toxin on B16F10 murine melanoma.

BACKGROUND: Malignant melanoma is a less common but highly dangerous form of skin cancer; it starts in the melanocytes cells found in the outer layer of the skin. Jararhagin toxin, a metalloproteinase isolated from Bothrops jararaca snake venom acts upon several biological processes, as inflammation, pain, platelet aggregation, proliferation and apoptosis, though not yet approved for use, may one day be employed to treat tumors. METHODS: B16F10 murine melanoma cells were treated with jararhagin (jara), a disintegrin-like metalloproteinase isolated from Bothrops jararaca snake venom, and jari (catalytic domain inactivated with 1,10-phenanthroline). Viability and adhesion cells were evaluated by MTT assay. The expression of caspase-3 active, phases of the cell cycle and apoptosis were assessed by flow cytometry. We analyze in vivo the effects of jararhagin on melanoma growth, apoptosis and metastasis. RESULTS: The tumor cells acquired round shapes, lost cytoplasmic expansions, formed clusters in suspension and decreased viability. Jari was almost 20 times more potent toxin than jara based on IC50 values and on morphological changes of the cells, also observed by scanning electron microscopy. Flow cytometry analysis showed 48.3% decrease in the proliferation rate of cells and 47.2% increase in apoptosis (jara) and necrosis (jari), following 1.2 µM jara and 0.1 µM jari treatments. Caspase-3 activity was increased whereas G0/G1 cell cycle phase was on the decline. Proliferative rate was assessed by staining with 5,6-carboxyfluoresceindiacetate succinimidyl ester, showing a significant decrease in proliferation at all concentrations of both toxins. CONCLUSIONS: In vivo treatment of the toxins was observed reduction in the incidence of nodules, and metastasis and antiproliferative inhibition capacity. This data strengthens the potential use jararhagin as an anti-neoplastic drug.

ADAMTS13 gene deletion aggravates ischemic brain damage: a possible neuroprotective role of ADAMTS13 by ameliorating postischemic hypoperfusion.

Reperfusion after brain ischemia causes thrombus formation and microcirculatory disturbances, which are dependent on the platelet glycoprotein Ib-von Willebrand factor (VWF) axis. Because ADAMTS13 cleaves VWF and limits platelet-dependent thrombus growth, ADAMTS13 may ameliorate ischemic brain damage in acute stroke. We investigated the effects of ADAMTS13 on ischemia-reperfusion injury using a 30-minute middle cerebral artery occlusion model in Adamts13(-/-) and wild-type mice. After reperfusion for 0.5 hours, the regional cerebral blood flow in the ischemic cortex was decreased markedly in Adamts13(-/-) mice compared with wild-type mice (P < .05), which also resulted in a larger infarct volume after 24 hours for Adamts13(-/-) compared with wild-type mice (P < .01). Thus, Adamts13 gene deletion aggravated ischemic brain damage, suggesting that ADAMTS13 may protect the brain from ischemia by regulating VWF-platelet interactions after reperfusion. These results indicate that ADAMTS13 may be a useful therapeutic agent for stroke.

[Clinical research on Sanmiao powder combined fibrinogenase for injection in treatment of acute deep venous thrombosis of lower limbs].

OBJECTIVE: To observe the clinical effectiveness of Sanmiao Powder (SP) combined fibrinogenase for injection in treatment of acute deep venous thrombosis (ADVT) of lower limbs. METHODS: Eighty patients with ADVT were randomly assigned to two groups according to the disease course (within 7 days or 7-28 days), 40 in each group. Every time phase was also divided into two groups, i. e., one group treated with fibrinogenase for injection alone (Group A and C) and another group treated with fibrinogenase for injection + SP administration (Group B and D) , 20 in each group. The clinical effectiveness was observed after 2-week treatment. RESULTS: The fibrinogenase for injection + SP administration showed better effects in alleviating the swelling of limbs, relieving pain, and lowering fibrinogen. Better effects were obtained in the group with the disease course less than 7 days. CONCLUSION: Better effect on ADVT was obtained by integrative medicine.

[Nonimmunogenic staphylokinase in the treatment of acute ischemic stroke (FRIDA trial results)]. / Neimmunogennaya stafilokinaza ­ novyi tromboliticheskii preparat v lechenii ishemicheskogo insul'ta (rezul'taty issledovaniya FRIDA).

AIM OF THE STUDY: To investigate the efficacy and safety of non-immunogenic staphylokinase (NS) compared with alteplase (A) in patients with acute ischemic stroke (AIS) within 4.5 h after symptom onset. MATERIAL AND METHODS: 336 patients with IS within 4.5 h after symptom onset were included in a randomized, open-label, multicenter, parallel-group, non-inferiority comparative trial of NS vs A (168 patients in each group). NS was administered as an intravenous bolus in a dose of 10 mg, regardless of body weight, over 10 s, A was administered as a bolus infusion in a dose of 0.9 mg/kg, maximum 90 mg over 1 hour. The primary efficacy endpoint was a favorable outcome, defined as a modified Rankin scale (mRS) score of 0-1 on day 90. Safety endpoints included all-cause mortality on day 90, symptomatic intracranial haemorrhage, and other serious adverse events (SAEs). RESULTS: At day 90, 84 (50%) patients reached the primary endpoint (mRS 0-1) in the NS group, 68 (41%) patients - in the A group (p=0.10, OR=1.47, 95% CI=0.93-2.32). The difference between groups NS and A was 9.5% (95% CI= -1.7-20.7) and the lower limit of the 95% CI did not cross the margin of non-inferiority (pnon-inferiority<0.0001). There were no significant differences in the frequency of deaths between the groups: on day 90, 17 (10%) patients in the NS group and 24 (14%) in the A group had died (p=0.32). There was a trend towards significant differences in the frequency of symptomatic intracranial haemorrhage: NS group - 5 (3%) patients, A group - 13 (8%) patients (p=0.087, OR=0.37, 95% CI=0.1-1.13). There were significant differences in the number of patients with SAEs: in the NS group - 22 (13%) patients, in the A group - 37 (22%) patients (p=0.044, OR=0.53, 95% CI=0.28-0.98). CONCLUSION: The presented results of the FRIDA trial are the first in the world to use a drug based on NS in patients with IS. It has been shown that a single bolus (within 10 s) administration of NS at a standard dose of 10 mg, regardless of body weight, allows to conduct fast, effective and safe thrombolytic therapy in patients with IS within 4.5 h after symptom onset. In further clinical tials of NS, it is planned to expand the therapeutic window beyond 4.5 h after symptom onset in patients with IS.

Intramuscular viral delivery of paraplegin rescues peripheral axonopathy in a model of hereditary spastic paraplegia.

Degeneration of peripheral motor axons is a common feature of several debilitating diseases including complicated forms of hereditary spastic paraplegia. One such form is caused by loss of the mitochondrial energy-dependent protease paraplegin. Paraplegin-deficient mice display a progressive degeneration in several axonal tracts, characterized by the accumulation of morphological abnormal mitochondria. We show that adenoassociated virus-mediated (AAV-mediated) intramuscular delivery of paraplegin halted the progression of neuropathological changes and rescued mitochondrial morphology in the peripheral nerves of paraplegin-deficient mice. One single injection before onset of symptoms improved the motor performance of paraplegin-deficient mice for up to 10 months, indicating that the peripheral neuropathy contributes to the clinical phenotype. This study provides a proof of principle that gene transfer may be an effective therapeutic option for patients with paraplegin deficiency and demonstrates that AAV vectors can be successfully employed for retrograde delivery of an intracellular protein to spinal motor neurons, opening new perspectives for several hereditary axonal neuropathies of the peripheral nerves.

Alfimeprase.

Alfimeprase, a fibrolase derivative with thrombolytic activity produced by recombinant DNA technology, was discovered by Amgen and was in development with Nuvelo for the treatment of stroke and catheter occlusion. However, development has been discontinued. Fibrolase is a zinc-containing metalloendopeptidase that was first isolated from the venom of the Southern copperhead snake, Agkistrodon contortrix contortrix. Alfimeprase directly degrades fibrin to break down clots. Alfimeprase is infused directly into the thrombus (side-hole catheter pushed through the entire clot) via multiple manual pulsed infusions. Alfimeprase degrades fibrin directly and entrapped blood cells are freed. Excess alfimeprase is rapidly inactivated by alpha-2 macroglobulin through an irreversible, covalent interaction. Phase III development of alfimeprase for peripheral arterial occlusion was discontinued based on poor results from the NAPA-2 and SONOMA-2 trials; however, Nuvelo resumed development of alfimeprase in 2007 for stroke and catheter occlusion.Alfimeprase's thrombolytic activity appears to be localized to the site of delivery because it is rapidly inactivated by alpha-2 macroglobulin, a naturally occurring protein in the blood, as it moves away from the site of delivery and into general blood circulation. In January 2002, Amgen and Hyseq Pharmaceuticals (now Nuvelo) entered into a collaboration to develop and commercialize alfimeprase. Nuvelo is to develop the product through clinical trials and Amgen was to be responsible for its manufacture. Both companies were to participate in commercial activities; Amgen was to have the option to lead these. Full financial terms were not disclosed. Further to this agreement, in November 2004 Amgen granted Nuvelo worldwide rights to develop and commercialize alfimeprase in exchange for milestone and royalty payments. In August 2007, Nuvelo decided to focus on core development programmes that it believed would produce the nearest-term proof-of-concept data. As a result of this realignment of organizational expenses, Nuvelo decided to continue to pursue the development of alfimeprase. In February 2003, Hyseq Pharmaceuticals merged with Variagenics Inc. to form Nuvelo Inc. In January 2006, Nuvelo and Bayer HealthCare entered a collaboration to develop and commercialize alfimeprase. Bayer was to commercialize the drug in all territories outside the US, whilst Nuvelo retains full US rights. Nuvelo was to receive other territory royalties and milestone payments to a total of $US385 million. A $US50 million upfront payment will be made to Nuvelo, while Bayer was to be responsible for 40% of the commercialization cost for global development. This partnership was to also develop stroke and deep vein thrombosis therapies. Data from the SONOMA-3 trial fell short of the company's expectations and so Nuvelo has decided to discontinue further development of alfimeprase. Nuvelo previously had decided to resume development of alfimeprase for the treatment of multiple coagulation-related disorders, including acute ischaemic stroke, catheter occlusion (CO) and acute peripheral arterial occlusion.Previously, results from the NAPA-2 (Novel Arterial Perfusion with Alfimeprase-2) trial and SONOMA-2 (Speedy Opening of Non-functional and Occluded catheters with Mini-dose Alfimeprase) phase III trial of alfimeprase in patients with acute peripheral arterial occlusion and catheter occlusion did not meet their primary endpoints. The primary endpoint of the NAPA-2 trial was the avoidance of surgery within 30 days of treatment with alfimeprase, whilst the SONOMA-2 trial's endpoint was the restoration of function at 15 minutes after dosing. In addition, these trials did not meet their secondary endpoints. As a result, Nuvelo and Bayer suspended enrolment in the NAPA-3 and SONOMA-3 phase III trials until additional analysis was complete; the SONOMA-3 trial was re-initiated. Nuvelo concluded that the delivery method for alfimeprase in the treatment of peripheral arterial occlusive disorders was suboptimal. The company closed the suspended NAPA-3 trial and planned to initiate preclinical studies focused on identifying optimized delivery methods in acute PAO in the second half of 2007. Data from the NAPA-2 trial suggested that efficacy could potentially be enhanced by maintaining alfimeprase longer at the site of the thrombus. Nuvelo's multinational phase III programme for peripheral arterial occlusion consisted of the NAPA-2 and NAPA-3 trials. Both trials were randomized, double-blind studies comparing 0.3 mg/kg of alfimeprase with placebo in a total of 600 patients in 100 centres. The primary endpoint of the NAPA-2 trial was the avoidance of surgery within 30 days of treatment; secondary endpoints included safety and pharmacoeconomics such as length of hospital and intensive care unit stay. Results from both trials have been presented. The phase II trial (NAPA-1) was completed in June 2004. This open-label, dose-escalation trial assessed the safety and efficacy of alfimeprase in 115 patients with acute peripheral arterial occlusion and was conducted in centres across the US, Europe and South Africa. Full data from the trial have been presented, which indicated that the 0.3 mg/kg dose appeared to be the optimal dose for investigation in phase III trials. In March 2003, Nuvelo announced the positive results of a phase I trial initiated in the US in July 2002; an IND was transferred from Amgen to Nuvelo in January 2002. In the SONOMA-2 trial, alfimeprase restored catheter function in patients with occluded catheters within 15 minutes with a p-value of 0.022. However, it did not meet the company's target product profile for commercial success with a p-value < 0.00125. Data from a phase II trial were presented at the 46th Annual Meeting of the American Society of Hematology held in December 2004. The study was closed in July 2004 with 55 patients enrolled. Initially the phase II study was to compare three doses of alfimeprase with the approved dose of alteplase in over 90 patients in the US. Nuvelo initiated the phase II CARNEROS-1 (Catheter Directed Alfimeprase for Restoration of Neurologic Function and Rapid Opening of Arteries in Stroke) study of alfimeprase in the treatment of acute ischaemic stroke in June 2007. CARNEROS-1 was a multicentre, open-label, dose-escalation study beginning with doses of 1, 5 and 10 mg of alfimeprase in 100 patients within 3-9 hours of stroke onset. The primary endpoints were recanalization (unblocking) of the occlusive lesion within 120 minutes of treatment, and symptomatic intracerebral haemorrhage. The first patient was dosed in December 2007; enrolment was taking place in the US and Canada. In the US, three patents have been issued relating to alfimeprase; US Patent Nos 6 261 820 (alfimeprase protein sequence), 6 440 414 (formulation of alfimeprase with a zinc stabilizer) and 6 455 269 (methods for localized administration of alfimeprase).

Nardilysin controls intestinal tumorigenesis through HDAC1/p53-dependent transcriptional regulation.

Colon cancer is a complex disease affected by a combination of genetic and epigenetic factors. Here we demonstrate that nardilysin (N-arginine dibasic convertase; NRDC), a metalloendopeptidase of the M16 family, regulates intestinal tumorigenesis via its nuclear functions. NRDC is highly expressed in human colorectal cancers. Deletion of the Nrdc gene in ApcMin mice crucially suppressed intestinal tumor development. In ApcMin mice, epithelial cell-specific deletion of Nrdc recapitulated the tumor suppression observed in Nrdc-null mice. Moreover, epithelial cell-specific overexpression of Nrdc significantly enhanced tumor formation in ApcMin mice. Notably, epithelial NRDC controlled cell apoptosis in a gene dosage-dependent manner. In human colon cancer cells, nuclear NRDC directly associated with HDAC1, and controlled both acetylation and stabilization of p53, with alterations of p53 target apoptotic factors. These findings demonstrate that NRDC is critically involved in intestinal tumorigenesis through its epigenetic regulatory function, and targeting NRDC may lead to a novel prevention or therapeutic strategy against colon cancer.

Drug evaluation: alfimeprase, a plasminogen-independent thrombolytic.

Alfimeprase is an analog of a fibrolase that disrupts formed thrombi through the hydrolysis of fibrin, rather than by activation of plasminogen. Nuvelo Inc, under license from Amgen Inc and together with Bayer AG, is developing this thrombolytic for the potential intravenous treatment of peripheral arterial occlusions and for other cardiovascular indications. Pharmacokinetic studies showed that alfimeprase was rapidly absorbed and achieved therapeutic concentrations at relatively low doses. Preclinical studies showed that adjunctive therapy with antiplatelet agents was necessary to maintain luminal patency. In phase I and II clinical trials alfimeprase effectively thombolysed clots with no drug-related adverse events. However, phase III clinical trials of alfimeprase did not meet their primary endpoints and enrollment in ongoing trials has been suspended pending further analyses and discussion with outside experts and regulatory agencies. In spite of this, the authors conclude that alfimeprase seems to be a lytic agent with much potential. Refinement in its use and dosing needs to be addressed, and further investigation into its pharmacokinetic properties may be worthwhile. Alfimeprase is a drug that is a 'work in progress'.

[A randomized multicenter trial comparing recombinant staphylokinase with recombinant tissue-type plasminogen activator in patients with acute myocardial infarction].

OBJECTIVE: The aim of the study was to compare the safety and clinical efficacy of recombinant staphylokinase (r-Sak) with recombinant tissue-type plasminogen activator (rt-PA) in patients with acute myocardial infarction (AMI). METHODS: This multicenter, open-label, randomized, parallel trial was conducted in 12 hospitals from January 2002 to October 2003. Patients (age < or = 70 years) with ST segment elevated AMI admitted within 12 hours of symptom onset were randomized to r-Sak (3 mg bolus followed by 12 mg intravenous infusion for 30 minutes, n = 104) or rt-PA (8 mg bolus followed by 42 mg intravenous infusion for 90 minutes, n = 106). All patients received aspirin and intravenous heparin and underwent angiography to determine infarct related artery (IRA) patency 90 minutes after drug therapy. Rescue percutaneous coronary intervention (PCI) was performed for patients with TIMI grade < or = 2. RESULTS: The IRA patency (TIMI grade 2 or 3), the primary end-point, was significantly higher in r-Sak group than that in rt-PA group (77.8% vs. 63.6%, P = 0.0277), the TIMI grade 3 flow was similar between the two groups (57.6% vs. 48.5%, P = 0.1929). One month post therapy, rates of death (8.7% vs. 5.7%, P = 0.3997), non-fatal myocardial infarction (2.9% vs. 3.8%, P = 1.0000), recurrent myocardial ischemia (8.7% vs. 16.0%, P = 0.1043) and composite clinical end-point (18.3% vs. 21.7%, P = 0.5345) were similar between the two groups. Hemorrhage occurred in 28.8% of patients receiving r-Sak and 27.4% of patients receiving rt-PA (P = 0.8105), severe and life-threatening hemorrhage rate (1.9% vs. 3.8%) as well as hemorrhagic stroke rate (0.96% vs.3.85%) were also no significant difference between the two groups. No anaphylactic reaction and other severe adverse events related to drug therapy were noted. CONCLUSION: The r-Sak is a safe and effective thrombolytic agent comparable to rt-PA for treatment of AMI.

Protection against Staphylococcus aureus and tetanus infections by a combined vaccine containing SasA and TeNT­Hc in mice.

In developing countries, trauma patients and neonates are vulnerable to Staphylococcus aureus (S. aureus) and Clostridium tetani infections. It has been suggested that a combined vaccine against the two infections may be a reliable and cost­effective strategy. Previous studies have indicated that the S. aureus surface protein A (SasA) and the C fragment of tetanus neurotoxin (TeNT­Hc) may be suitable candidates for a vaccine against S. aureus and tetanus infections, respectively. In the present study, mice were immunized with a combined vaccine containing SasA and TeNT­Hc, which induced a robust immune response to both antigens, and mutual interference between SasA and TeNT­Hc was not observed. In the S.aureus challenge model, the combined vaccine fully protected BALB/c mice against lethal intraperitoneal challenges with 3x109 colony­forming units of a methicillin­resistant S. aureus USA300 strain. In the TeNT challenge model, the combined vaccine conferred complete protection against a lethal dose of (2x103) xLD50 tetanus toxin. These results implied that SasA and TeNT­Hc promising components for a combined vaccine against S. aureus and tetanus infections.

Conjugates of Cell Adhesion Peptides for Therapeutics and Diagnostics Against Cancer and Autoimmune Diseases.

Overexpressed cell-surface receptors are hallmarks of many disease states and are often used as markers for targeting diseased cells over healthy counterparts. Cell adhesion peptides, which are often derived from interacting regions of these receptor-ligand proteins, mimic surfaces of intact proteins and, thus, have been studied as targeting agents for various payloads to certain cell targets for cancers and autoimmune diseases. Because many cytotoxic agents in the free form are often harmful to healthy cells, the use of cell adhesion peptides in targeting their delivery to diseased cells has been studied to potentially reduce required effective doses and associated harmful side-effects. In this review, multiple cell adhesion peptides from extracellular matrix and ICAM proteins were used to selectively direct drug payloads, signal-inhibitor peptides, and diagnostic molecules, to diseased cells over normal counterparts. RGD constructs have been used to improve the selectivity and efficacy of diagnostic and drug-peptide conjugates against cancer cells. From this precedent, novel conjugates of antigenic and cell adhesion peptides, called Bifunctional Peptide Inhibitors (BPIs), have been designed to selectively regulate immune cells and suppress harmful inflammatory responses in autoimmune diseases. Similar peptide conjugations with imaging agents have delivered promising diagnostic methods in animal models of rheumatoid arthritis. BPIs have also been shown to generate immune tolerance and suppress autoimmune diseases in animal models of type-1 diabetes, rheumatoid arthritis, and multiple sclerosis. Collectively, these studies show the potential of cell adhesion peptides in improving the delivery of drugs and diagnostic agents to diseased cells in clinical settings.

Plasminogen activators: a comparison.

Thrombolytic drugs play a crucial role in the management of patients with acute myocardial infarction, pulmonary embolism, deep vein thrombosis, arterial thrombosis, acute thrombosis of retinal vessel, extensive coronary emboli, and peripheral vascular thromboembolism. Recognition of the importance of fibrinolytic system in thrombus resolution has resulted in the development of different fibrinolytic agents. Now a days several newer plasminogen activators with different pharmacokinetic and pharmacodynamic properties have been developed to treat thrombotic disease, which are fibrin specific with prolonged half-life and can be administered as a single bolus.

Evidence of antiangiogenic and antimetastatic activities of the recombinant disintegrin domain of metargidin.

Metargidin, a transmembrane protein of the adamalysin family, and integrins, e.g., alpha5beta1 and alphav, are preferentially expressed on endothelial cells on angiogenesis. Furthermore, metargidin interacts with these integrins via its disintegrin domain. In this study, recombinant human disintegrin domain (RDD) was produced in Escherichia coli by subcloning its cDNA into the pGEX-2T vector, and the effect of purified RDD on different steps of angiogenesis was evaluated. At concentrations of 2-10 micro g/ml, RDD exhibited inhibitory activities in a variety of in vitro functional assays, including endothelial cell proliferation and adhesion on the integrin substrates fibronectin, vitronectin, and fibrinogen. RDD (10 micro g/ml) totally abrogated endothelial cell migration and blocked most capillary formation in a three-dimensional fibrin gel. To test RDD efficacy in vivo, the RDD gene inserted into pBi vector containing a tetracycline-inducible promoter was electrotransferred into nude mouse muscle. RDD was successfully synthesized by muscle cells in vivo as shown by immunolabeling and Western blotting. In addition, 78% less MDA-MB-231 tumor growth, associated with strong inhibition of tumor angiogenesis, was observed in athymic mice bearing electrotransferred RDD. Moreover, in the presence of RDD, 74% fewer B16F10 melanoma lung metastases were found in C57BL/6 mice. Taken together, these results identified this RDD as a potent intrinsic inhibitor of angiogenesis, tumor growth, and metastasis, making it a promising tool for use in anticancer treatment.

[Staphylokinase--a specific plasminogen activator]. / Stafylokinaza--selektywny aktywator plazminogenu.

Staphylokinase is a 135 amino acid protein produced by certain strains of Staphylococcus aureus. It belongs to fibrin-specific plasminogen activator. Staphylokinase converts plasminogen--the inactive proenzyme--to the plasmin, which dissolves the fibrin of a blood clots. This review will focus on the biochemical and thrombolytic properties of staphylokinase and its derivatives, which would make use of treatment in acute myocardial infarction and other cardiovascular diseases.

Liposomal nanocarriers for plasminogen activators.

Several plasminogen activators (PAs) have been found effective in treating different thromboembolic diseases. However, administration of conventional thrombolytic therapy is limited by a low efficacy of present formulations of PAs. Conventional treatments using these therapeutic proteins are associated with several limitations including rapid inactivation and clearance, short half-life, bleeding complications or non-specific tissue targeting. Liposome-based formulations of PAs such as streptokinase, tissue-plasminogen activator and urokinase have been developed to improve the therapeutic efficacy of these proteins. Resulting liposomal formulations were found to preserve the original activity of PAs, promote their selective delivery and improve thrombus targeting. Therapeutic potential of these liposome-based PAs has been demonstrated successfully in various pre-clinical models in vivo. Reductions in unwanted side effects (e.g., hemorrhage or immunogenicity) as well as enhancements of efficacy and safety were achieved in comparison to currently existing treatment options based on conventional formulations of PAs. This review summarizes present achievements in: (i) preparation of liposome-based formulations of various PAs, (ii) development of PEGylated and targeted liposomal PAs, (iii) physico-chemical characterization of these developed systems, and (iv) testing of their thrombolytic efficacy. We also look to the future and the imminent arrival of theranostic liposomal formulations to move this field forward.

Polyethylene glycol-derivatized cysteine-substitution variants of recombinant staphylokinase for single-bolus treatment of acute myocardial infarction.

BACKGROUND: Thrombolytic therapy of acute myocardial infarction (AMI) is evolving toward bolus administration. Derivatization of proteins with polyethylene glycol (PEG) may reduce their clearance. METHODS AND RESULTS: A staphylokinase (SakSTAR) variant with 12 amino acid substitutions to reduce its antigenicity, SakSTAR (K35A, E65Q, K74R, E80A, D82A, T90A, E99D, T101S, E108A, K109A, K130T, K135R), and with Ser in position 3 mutated into Cys (code SY161), was derivatized with maleimide-PEG with M:(r) of 5,000 (P5), 10,000 (P10), or 20,000 (P20). The PEGylated variants recognized only one third of the antibodies elicited with wild-type SakSTAR in AMI patients. In experimental animals, plasma clearances were reduced 2. 5- to 5-fold with P5, 5- to 20-fold with P10, and 20-fold with P20, and bolus injection induced pulmonary plasma clot lysis at doses inversely related to their clearance. Intravenous bolus injection of 5 mg of the P5, P10, or P20 variants in AMI patients was associated with plasma half-lives (t(1/2alpha)) of 13, 30, and 120 minutes and clearances of 75, 43, and 8 mL/min, respectively, compared with 3 minutes and 360 mL/min for SakSTAR. Injection of 5 mg P5 variant restored TIMI-3 flow within 60 minutes in 14 of 18 AMI patients (78%, 95% CI 55% to 91%) and of 2.5 mg in 7 of 11 patients (63%, 95% CI 35% to 85%), both in the absence of fibrinogen degradation. The immunogenicity of the variants was significantly (P:<0.002) reduced. CONCLUSIONS: The staphylokinase variant SY161-P5, derivatized with one linear polyethylene glycol molecule of M:(r) 5000, is a promising fibrin-selective agent for single-bolus coronary thrombolysis.