Thrombolytic Enzymes of Microbial Origin: A Review

Anticoagulation Management: Current Landscape and Future Trends

Blood transports nutrients and oxygen to the cells while removing the waste. It also possesses a hemostasis function to prevent excessive bleeding. However, abnormal clot formation (thrombosis) within healthy blood vessels can lead to life-threatening conditions like heart attacks, strokes, and pulmonary embolism. This review explores anticoagulants, their historical aspects, current clinical applications, and future trends. Anticoagulants play a critical role in preventing and treating thrombosis by interfering with different stages of blood clotting. The journey began with heparin, a rapidly acting injectable medication discovered in 1916. The introduction of warfarin in the 1950s revolutionized anticoagulation by offering long-term oral regimens. Today, anticoagulants are crucial for managing conditions like deep vein thrombosis and pulmonary embolism, especially in an aging population with a rising prevalence of thrombotic complications. Three main types of anticoagulants are used today: vitamin K antagonists (VKAs), injectable heparins, and direct oral anticoagulants (DOACs). Despite advancements, managing anticoagulant therapy remains complex due to individual patient variability, the need for regular monitoring, and the delicate balance between preventing thrombosis and bleeding risks. Emerging trends include the development of factor XIa inhibitors, which promise more targeted thrombosis prevention with potentially lower bleeding risks. This review highlights the ongoing innovation in anticoagulant development, the need for precise management, and potential future avenues like factor XIa inhibitors. Additionally, artificial intelligence holds promise for improving patient outcomes and addressing the complexities of thrombotic disease management by personalizing therapy and reducing bleeding risks.

Application of microbial enzymes in medicine and industry: current status and future perspectives

Microbes are a major source of enzymes due to their ability to be mass-cultivated and genetically modified. Compared with plant and animal enzymes, microbial enzymes are more stable and active. Enzymes are generally classified into six classes based on their reaction, substrate specificity and mechanism of action. In addition to their application in medicine for treating diseases, these compounds are used as anti-inflammatory, thrombolytic and digestive agents. However, challenges such as immunogenicity, tissue specificity and short in vivo half-life make clinical trials complex. Enzymes are metabolic catalysts in industry and their production and extraction must be optimized to preserve profitability due to rising demand. The present review highlights the increasing importance of bacterial enzymes in industry and medicine and explores methods for their production, extraction and purification.

Development of a Methodology Based on Optical Interferometry for Measuring Fibrinolytic Activity

Fibrinolytic activity assay is particularly important for the detection, diagnosis, and treatment of cardiovascular disease and the development of fibrinolytic drugs. A novel efficacious strategy for real-time and label-free dynamic detection of fibrinolytic activity based on ordered porous layer interferometry (OPLI) was developed. Fibrin or a mixture of fibrin and plasminogen (Plg) was loaded into the highly ordered silica colloidal crystal (SCC) film scaffold to construct a fibrinolytic response interference layer to measure fibrinolytic activity with different mechanisms of action. Fibrinolytic enzyme-triggered fibrinolysis led to the migration of interference fringes in the interferogram, which could be represented by optical thickness changes (ΔOT) tracked in real time by the OPLI system. The morphology and optical property of the fibrinolytic response interference layer were characterized, and the Plg content in the fibrinolytic response interference layer and experimental parameters of the system were optimized. The method showed adequate sensitivity for the fibrinolytic activity of lumbrokinase and streptokinase, with wide linear ranges of 12-6000 and 10-2000 U/mL, respectively. Compared with the traditional fibrin plate method, it has a lower detection limit and higher linearity. The whole kinetic process of fibrinolysis by these two fibrinolytic drug models was recorded in real time, and the Michaelis constant and apparent kinetic parameters were calculated. Importantly, some other blood proteins were less interfering with this system, and it showed reliability in fibrin activity detection in real whole blood samples. This study established a better and more targeted research method of in vitro fibrinolysis and provided dynamic monitoring data for the analysis of fibrinolytic activity of whole blood.

Split intein-mediated backbone cyclization enhances the stability and activity of staphylokinase, a potent fibrin-selective plasminogen activator

Staphylokinase (Sak), a small 15 kDa globular protein that is secreted by certain strains of Staphylococcus aureus, shows a potent fibrin-selective thrombolytic activity. Earlier work has shown that Sak could potentially become a low-cost alternative to currently used thrombolytic agents, such as tissue plasminogen activator (tPA). In attempts to improve its potential for clinical applications, numerous modifications of Sak have already been investigated. Here, we have characterized a novel Sak modification, cyclized Sak (cyc-Sak), which was prepared through split-intein mediated protein backbone cyclization. We have characterized the structure, stability and the activity of cyc-Sak using biophysical techniques, limited proteolysis studies and plasminogen (PG)-activation assays. Our results show that cyc-Sak possesses an identical structure, enhanced stability, resistance to proteolysis by exoproteases and improved PG-activation properties compared to its linear counterpart. It can be over-expressed with high yield in the cytoplasm of Escherichia coli and is easily purified in a two-step process. The intein-mediated cyclization occurs spontaneously in vivo during protein expression and does not necessitate further modification steps after purification of the protein. Furthermore, covalent Sak cyclization could be readily combined with other Sak modifications previously proposed, to generate an effective thrombolytic agent with lower immunogenicity and improved stability and activity.

Fibrinogen binding to activated platelets and its biomimetic thrombus-targeted thrombolytic strategies

Thrombosis is associated with various fatal arteriovenous syndromes including ischemic stroke, myocardial infarction, and pulmonary embolism. However, current clinical thrombolytic treatment strategies still have many problems in targeting and safety to meet the thrombolytic therapy needs. Understanding the molecular mechanism that underlies thrombosis is critical in developing effective thrombolytic strategies. It is well known that platelets play a central role in thrombosis and the binding of fibrinogen to activated platelets is a common pathway in the process of clot formation. Based on this, a concept of biomimetic thrombus-targeted thrombolytic strategy inspired from fibrinogen binding to activated platelets in thrombosis was proposed, which could selectively bind to activated platelets at a thrombus site, thus enabling targeted delivery and local release of thrombolytic agents for effective thrombolysis. In this review, we first summarized the main characteristics of platelets and fibrinogen, and then introduced the classical molecular mechanisms of thrombosis, including platelet adhesion, platelet activation and platelet aggregation through the interactions of activated platelets with fibrinogen. In addition, we highlighted the recent advances in biomimetic thrombus-targeted thrombolytic strategies which inspired from fibrinogen binding to activated platelets in thrombosis. The possible future directions and perspectives in this emerging area are briefly discussed.

Maggot Kinase and Natural Thrombolytic Proteins

Thrombolytic enzymes constitute a class of proteases with antithrombotic functions. Derived from natural products and abundant in nature, certain thrombolytic enzymes, such as urokinase, earthworm kinase, and streptokinase, have been widely used in the clinical treatment of vascular embolic diseases. Fly maggots, characterized by their easy growth and low cost, are a traditional Chinese medicine recorded in the Compendium of Materia Medica. These maggots can also be used as raw material for the extraction and preparation of thrombolytic enzymes (maggot kinase). In this review, we assembled global research reports on natural thrombolytic enzymes through a literature search and reviewed the functions and structures of natural thrombolytic enzymes to provide a reference for natural thrombophilic drug screening and development.

Recent trends in targeted delivery of smart nanocarrier-based microbial enzymes for therapeutic applications

Smart carrier-based immobilization has widened the use of enzymes for the treatment of several disorders. Large surface areas, tunable morphology, and surface modification ability aid the targeted and controlled release of therapeutic enzymes from such formulations. Smart nanocarriers, such as polymeric carriers, liposomes, and silica have also increased the stability, half-life, and permeability of these enzymes. In this review, summarize recent advances in the smart immobilization of microbial enzymes and their development as precision nanomedicine for the treatment of cancer, thrombosis, phenylketonuria (PKU), and wound healing. We also discuss the challenges and measures to be adopted for the successful clinical translation of these formulations.

The Conservation and Study of Macromycetes in the Komarov Botanical Institute Basidiomycetes Culture Collection-Their Taxonomical Diversity and Biotechnological Prospects

Culture collections (CCs) play an important role in the ex situ conservation of biological material and maintaining species and strains, which can be used for scientific and practical purposes. The Komarov Botanical Institute Basidiomycetes Culture Collection (LE-BIN) preserves a large number of original dikaryon strains of various taxonomical and ecological groups of fungi from different geographical regions. Started in the late 1950s for the investigation of Basidiomycetes' biological activity, today, in Russia, it has become a unique specialized macromycetes collection, preserving 3680 strains from 776 species of fungi. The Collection's development is aimed at ex situ conservation of fungal diversity, with an emphasis on preserving rare and endangered species, ectomycorrhizal fungi, and strains useful for biotechnology and medicine. The main methods applied in the collection for maintaining and working with cultures are described, and the results are presented. Some problems for the isolation and cultivation of species are discussed. The taxonomical structure and variety of the strains in the collection fund are analyzed, and they show that the taxonomical diversity of fungi in the LE-BIN is commensurable with the largest CCs in the world. The achievements from the ex situ conservation of the diversity of macromycetes and the main results from the screening and investigation of the collection's strains demonstrate that a number of strains can be prospective producers of enzymes (oxidoreductases and proteases), lipids, and biologically active compounds (terpenoids, phthalides, etc.) for biotechnology and medicine.

ROS-responsive phenylboronic ester-based nanovesicles as multifunctional drug delivery systems for the treatment of inflammatory and thrombotic complications

Inflammatory and thrombotic complications and a low loading of dual drugs with different hydrophilicities remain challenges to treat thrombosis with drug delivery systems (DDSs). Here, the reactive oxygen species (ROS)-responsive amphiphilic block polymer poly(ethylene glycol)-b-2-((((4-(4,4,5,5-tetramethyl-1,3,2-dioxaborolan-2-yl)benzyl)oxy)carbonyl)oxy)-ethyl methacrylate (PEG-b-PTBEM) was synthesized and nanovesicles (PPTV) were prepared successfully for the drug delivery platform by controlling the hydrophilic/hydrophobic ratio of molecular chains and molecular self-assembly. The anti-inflammatory drug indomethacin (IDM) was loaded in the wall of nanovesicles and the thrombolytic enzyme nattokinase (NK) was encapsulated in the aqueous cavity of nanovesicles. Both drugs could be rapidly released at the site of thrombosis and/or inflammation with an excessive ROS concentration. The dual drug-loaded nanovesicles not only eliminated ROS, but also alleviated inflammation and dissolved the generated thrombus, showing significant therapeutic efficacy in the in vivo mouse model of carrageenan tail thrombosis. Therefore, drug-delivery nanovesicles play multiple roles in the treatment of inflammation-induced thrombotic disorders, which offer a promising treatment for inflammatory and thrombotic complications.

Changes in the Fibrinolytic System of Patients Infected with Severe Acute Respiratory Syndrome Coronavirus 2

INTRODUCTION

In this study, coagulation and fibrinolysis parameters and their association with disease severity were investigated in coronavirus disease (COVID-19) patients.

MATERIALS AND METHODS

COVID-19 patients (n = 446) admitted to our institute between 21 February 2021 and 17 March 2022, were recruited. Clinical data and staging were collected from all patients. Blood samples were collected and analyzed for several parameters of fibrinolysis and coagulation, including alpha-2-antiplasmin(α2AP) and plasminogen, thrombin activatable fibrinolysis inhibitor (TAFI), tissue plasminogen activator (tPA), plasminogen activator inhibitor-1 (PAI-1), D-dimer, and fibrinogen levels.

RESULTS

The TAFI, fibrinogen, and tPA levels were significantly higher in participants who died compared to that of patients who recovered (p < 0.001). However, PAI-1, tPA, and TAFI were significantly higher in patients admitted to the ICU than those of the healthy controls (p < 0.001 for PAI-1 and tPA; p = 0.0331 for TAFI). Our results showed that stage C and D COVID-19 patients had significantly higher levels of PAI-1 (p = 0.003). Furthermore, stage D COVID-19 patients had significantly higher tPA and TAFI values (p = 0.003).

CONCLUSIONS

Hypofibrinolysis was the most prevalent condition among patients with severe COVID-19. In this study, several coagulation markers were elevated, making them suitable prognostic markers for hypofibrinolysis.

The potential role of ischaemia-reperfusion injury in chronic, relapsing diseases such as rheumatoid arthritis, Long COVID, and ME/CFS: evidence, mechanisms, and therapeutic implications

Ischaemia-reperfusion (I-R) injury, initiated via bursts of reactive oxygen species produced during the reoxygenation phase following hypoxia, is well known in a variety of acute circumstances. We argue here that I-R injury also underpins elements of the pathology of a variety of chronic, inflammatory diseases, including rheumatoid arthritis, ME/CFS and, our chief focus and most proximally, Long COVID. Ischaemia may be initiated via fibrin amyloid microclot blockage of capillaries, for instance as exercise is started; reperfusion is a necessary corollary when it finishes. We rehearse the mechanistic evidence for these occurrences here, in terms of their manifestation as oxidative stress, hyperinflammation, mast cell activation, the production of marker metabolites and related activities. Such microclot-based phenomena can explain both the breathlessness/fatigue and the post-exertional malaise that may be observed in these conditions, as well as many other observables. The recognition of these processes implies, mechanistically, that therapeutic benefit is potentially to be had from antioxidants, from anti-inflammatories, from iron chelators, and via suitable, safe fibrinolytics, and/or anti-clotting agents. We review the considerable existing evidence that is consistent with this, and with the biochemical mechanisms involved.