Search Results (97)

Alpha2-plasmin inhibitor (α2PI) has a heterogeneous structure due to proteolytic cleavages in the circulation. The C-terminally cleaved form loses the plasminogen binding site and is, therefore, a slow plasmin inhibitor (NPB-α2PI). As FXIII primarily crosslinks the plasminogen-binding intact form (PB-α2PI) to fibrin, the effect of NPB-α2PI on fibrinolysis has been less studied. Herein, we investigated the effect of C-terminal truncation. Total-, PB-, and NPB-α2PI antigen levels and α2PI incorporation were measured by ELISAs from samples of 80 healthy individuals. Clot lysis parameters of the same subjects were investigated using an in vitro clot lysis assay. α2PI incorporation into the clot was demonstrated by Western blotting. Clot lysis and clot structure were also analyzed using an α2PI-deficient plasma substituted with recombinant PB- and NPB-α2PI. Both plasma and clot-bound levels of total- and NPB-α2PI showed a significant positive correlation with clot lysis parameters. NPB-α2PI was detected in the clot due to non-covalent binding. Regardless of the type of binding, both forms affected the clot structure by increasing the thickness of the fibrin fibers and reducing the pore size. In conclusion, we found that NPB-α2PI can bind non-covalently to fibrin, and this binding contributes to changes in clot structure and inhibition of fibrinolysis. Full article

Background: Risk assessment in hyperthyroidism remains challenging. The aim of the present study is to determine the influence of hyperthyroid metabolic status on blood clotting and an increased risk of thrombosis. Methods: This prospective study included 50 patients after radical thyroidectomy and ablative radioiodine therapy because of thyroid carcinoma who were compared with 50 control subjects in a euthyroid metabolic state. Latent hyperthyroid patients with basal thyroid-stimulating hormone (TSH) ≤ 0.15 mU/L on levothyroxine hormone therapy were included. The control group was selected to match the patient group based on age and sex. The evaluation data were collected using laboratory coagulation tests and patient questionnaires. A bleeding and a thrombosis score were determined. Results: The coagulation parameters between the patient and control groups showed statistically significant differences. In particular, the patients’ group showed a significantly shortened activated partial thromboplastin time (aPTT/p = 0.009) and a significantly higher plasminogen activator inhibitor 1 (PAI-1/p < 0.001) compared to the control group. Age, sex, and medication use were not found to influence the patients’ laboratory results. Only body mass index was higher in the patient group than in the control group. Conclusions: Our results support a shift in the coagulation system in latent hyperthyroid metabolism towards increased coagulability and reduced fibrinolysis. A latent hyperthyroid metabolic state appears to be associated with an increased risk of thrombosis. Further prospective cohort studies with large patient populations are needed to verify the association between (latent) hyperthyroidism and thromboembolic events as well as to determine therapeutic anticoagulation or to adjust the indication for exogenous administration of thyroid hormone. Full article

Chronic obstructive pulmonary disease (COPD) is a major cause of morbidity and mortality worldwide, primarily driven by chronic airway inflammation due to cigarette smoke exposure. Despite its burden, however, current anti-inflammatory therapies offer limited efficacy in preventing disease progression. Plasminogen activator inhibitor-1 (PAI-1), as a key regulator of fibrinolysis, has recently been implicated in structural airway changes and persistent inflammation in patients with COPD. This study aimed to investigate the ability of the PAI-1 inhibitor TM5441 to attenuate airway inflammation and structural lung damage induced by a cigarette smoke extract (CSE) in a mouse model. Mice received intratracheal CSE or vehicle on days 1, 8, and 15, and were sacrificed on day 22. TM5441 (20 mg/kg) was administered orally from days 1 to 22. The CSE significantly increased the mean linear intercept, destructive index, airway resistance, and reductions in dynamic compliance. The CSE also increased the numbers of neutrophils and macrophages in the bronchoalveolar lavage fluid, systemic PAI-1 activity, and neutrophil elastase mRNA and protein expression in the lungs. TM5441 treatment significantly suppressed these changes without affecting coagulation time. These findings suggest that TM5441 may be a novel therapeutic agent for COPD by targeting PAI-1-mediated airway inflammation and emphysema. Full article

Objectives: This study investigated the antithrombotic properties of a fibrinolytic enzyme (CFE) purified from the culture supernatant of Coprinus comatus using a zebrafish thrombosis model. Methods: A phenylhydrazine-induced thrombosis model was employed to evaluate the in vivo thrombolytic efficacy and mechanisms of CFE. Results: CFE significantly attenuated thrombogenesis by inhibiting erythrocyte aggregation in the caudal vessels, reducing staining intensity (3.61-fold decrease) and staining area (3.89-fold decrease). Concurrently, CFE enhanced cardiac hemodynamics, increasing erythrocyte staining intensity (9.29-fold) and staining area (5.55-fold) while achieving an 85.19% thrombosis inhibition rate. Behavioral analysis confirmed improved motility, with CFE-treated zebrafish exhibiting 2.23-fold increases in total movement distance and average speed, alongside a 3.59-fold extension in active movement duration. Mechanistically, ELISA revealed the multi-pathway activity of CFE, promoting fibrinolysis through reductions in plasminogen, fibrinogen, and D-dimer; inhibiting platelet activation via downregulation of prostaglandin-endoperoxide synthase (PTGS), thromboxane A2 (TXA2), P-selectin, and von Willebrand factor (vWF); and modulating coagulation cascades through elevated protein C and tissue factor pathway inhibitor (TFPI) with concurrent suppression of coagulation factor VII (FVII). Conclusions: These results indicate that the fibrinolytic enzyme CFE, derived from Coprinus comatus, exerts potent antithrombotic effects, supporting its potential as a basis for fungal-derived natural antithrombotic functional food ingredients. Full article

Reactive nitrogen species (RNS), particularly peroxynitrite (ONOO⁻), play a central role in post-translational modifications (PTMs) of proteins, including fibrinogen, a key component of the coagulation cascade. This review explores the structural and functional consequences of fibrinogen nitration, with a focus on its impact on clot formation, morphology, mechanical stability, and fibrinolysis. Nitration, primarily targeting tyrosine residues within functional domains of the Aα, Bβ, and γ chains, induces conformational changes, dityrosine crosslinking, and aggregation into high molecular weight species. These modifications result in altered fibrin polymerization, the formation of porous and disorganized clot networks, reduced mechanical resilience, and variable susceptibility to fibrinolysis. Moreover, nitrated fibrinogen may affect interactions with platelets and endothelial cells, although current evidence remains limited. Emerging clinical studies support its role as both a prothrombotic mediator and a potential biomarker of oxidative stress in cardiovascular and inflammatory diseases. Finally, we explore both pharmacological interventions, such as NOX inhibitors, and natural antioxidant strategies at counteracting fibrinogen nitration. Overall, fibrinogen nitration emerges as a critical molecular event linking oxidative stress to thrombotic risk. Full article

Naturally occurring plant-based compounds are increasingly being explored for their therapeutic potential in treating a wide range of conditions, particularly those related to vascular health. The compound 3-deoxysappanchalcone (3-DSC), derived from Caesalpinia sappan L., has been proven to exhibit anti-inflammatory, anti-influenza, and anti-allergic properties, though its role in thrombosis and haemostasis remains unexplored. This study aimed to evaluate the anti-thrombotic potential of 3-DSC in both in vitro and in vivo models. The anticoagulant activities of 3-DSC were assessed using activated partial thromboplastin time (aPTT), prothrombin time (PT), and thrombin (FIIa) and activated factor X (FXa) activity assays, as well as fibrin polymerization and platelet aggregation tests. Its effects on plasminogen activator inhibitor type 1 (PAI-1) and tissue-type plasminogen activator (t-PA) expression were evaluated in TNF-α-stimulated human umbilical vein endothelial cells (HUVECs). The results demonstrated that 3-DSC extended aPTT and PT, suppressed thrombin and FXa activities, reduced their production in HUVECs, inhibited thrombin-induced fibrin polymerization and platelet aggregation, and exerted anticoagulant effects in mice. Furthermore, 3-DSC significantly decreased the PAI-1 to t-PA ratio. These findings suggest that 3-DSC possesses potent anti-thrombotic properties by modulating coagulation pathways and fibrinolysis. Its therapeutic potential warrants further investigation for the development of novel anticoagulant agents. Full article

Immune checkpoint inhibitors (ICIs) have revolutionized cancer treatment, but their association with thrombosis presents significant clinical challenges. Patients with cancer already exhibit elevated risks for venous thromboembolism and arterial thrombosis, with treatment modalities like chemotherapy further exacerbating this risk. Emerging evidence suggests that ICIs contribute to thrombotic events through multifactorial mechanisms, including immune dysregulation, T cell activation, endothelial dysfunction, elevated tissue factor expression, and impaired fibrinolysis. Additional risk factors such as obesity, smoking, prior thrombotic events, and combination ICI therapy further increase thrombosis susceptibility. The literature reports varying incidence rates of ICI-associated thrombosis, with some studies indicating comparable risks to chemotherapy, while others highlight higher rates, particularly during the initial treatment phase. Management aligns with standard protocols for cancer-associated thrombosis, using low-molecular-weight heparin or direct oral anticoagulants, though optimal treatment duration and the role of prophylactic anticoagulation require further investigation. This review provides a comprehensive overview of the mechanisms, incidence rates, and clinical management strategies of ICI-associated thrombosis, emphasizing the importance of proactive risk assessment to optimize patient outcomes. Full article

In response to vaccination and/or infectious agents, the liver produces acute-phase proteins (APPs) driven by IL-6, which circulate in blood plasma as components of the humoral innate defense. This study investigates the liver of mice for possible effects of protective vaccination against primary blood-stage infections of Plasmodium chabaudi malaria on the expression of genes encoding APPs and IL-6 family members. Female Balb/c mice were vaccinated with a non-infectious vaccine prior to challenge with 10⁶ P. chabaudi-infected erythrocytes, resulting in about 80% survival of otherwise lethal infections. Gene expression microarrays were used to determine the relative transcript levels of genes in the livers of vaccinated and unvaccinated mice on days 0, 1, 4, 8, and 11 p.i. (post infectionem). Vaccination induced significant (p-value < 0.05) differences in the expression of malaria-responsive genes toward the end of crisis on day 11 p.i., when mice recovered from infections. These genes include Saa4, Apcs, Cp, and Crp, encoding APPs described to inhibitorily interact with parasitic blood stages; the genes F2, F7, F8, F9, F10, and F13b, and Plg, Plat, and Serpina5, encoding proteins balancing coagulation vs. fibrinolysis dysregulated by malaria, respectively; the genes Hc, C8a, C8b, C8g, and C9, encoding components of lytic complement membrane attack complex (MAC); and Cfh, Cfi, and C4bp, encoding complement-regulatory proteins. Vaccination accelerated, albeit differently, the malaria-induced activation of all three complement pathways, evidenced as higher transcript levels of C1qa, C1qb, C1qc, Fcna, Cfp, C3, Cfh, C8a, and C9 on day 4 p.i., C1ra, C1s, and C2 on day 1 p.i., and Serping1, encoding the multifunctional protease inhibitor C1INH, on day 0 p.i. Protective vaccination may also accelerate downregulation of the malaria-promoting lethality of IL-6 trans-signaling, which may contribute to an overall accelerated recovery of mice from otherwise lethal blood-stage malaria. Full article

Fibrinogen, a pivotal plasma glycoprotein, plays an essential role in hemostasis by serving as the precursor to fibrin, which forms the structural framework of blood clots. Beyond coagulation, fibrinogen influences immune responses, inflammation, and tissue repair. Oxidative stress, characterized by an imbalance between reactive oxygen species (ROS) and antioxidants, induces fibrinogen oxidation, significantly altering its structure and function. This narrative review synthesizes findings from in vitro, ex vivo, and clinical studies, emphasizing the impact of fibrinogen oxidation on clot formation, architecture, and degradation. Oxidative modifications result in denser fibrin clots with thinner fibers, reduced permeability, and heightened resistance to fibrinolysis. These structural changes exacerbate prothrombotic conditions in cardiovascular diseases, diabetes, chronic inflammatory disorders and cancer. In contrast, “low-dose” oxidative stress may elicit protective adaptations in fibrinogen, preserving its function. The review also highlights discrepancies in experimental findings due to variability in oxidation protocols and patient conditions. Understanding the interplay between oxidation and fibrinogen function could unveil therapeutic strategies targeting oxidative stress. Antioxidant therapies or selective inhibitors of detrimental oxidation hold potential for mitigating thrombotic risks. However, further research is essential to pinpoint specific fibrinogen oxidation sites, clarify their roles in clot dynamics, and bridge the gap between basic research and clinical practice. Full article

Serine proteases, a significant class of enzymes comprising approximately one-third of known human proteases, are ubiquitously present across various organisms. These enzymes typically exhibit highly conserved catalytic domain structures, and their activity is stringently regulated within the body, playing a pivotal role in numerous physiological processes. Dysregulation of serine protease activity can result in severe consequences, including excessive inflammation, heightened risk of thrombosis and cancer, and even mortality. Serine protease inhibitors have emerged as critical regulators, offering a broad range of physiological functions such as maintaining the coagulation–fibrinolysis balance, modulating inflammatory responses, accelerating wound healing, promoting apoptosis, and providing antitumor and antiviral effects. As a result, the development of serine protease inhibitors has become increasingly vital. In recent years, significant progress in the study of serine proteases has led to the pivotal role of various serine protease inhibitors in clinical diagnosis and treatment. This review explores the fundamental mechanisms of serine protease inhibitors, summarizes those that have been successfully integrated into clinical practice, and discusses the challenges encountered in their development along with partial solutions. These advancements lay the groundwork for further refinement and innovation in serine protease inhibitor therapeutics. Full article

Background: The thrombin-activatable fibrinolysis inhibitor (TAFI) is an important regulator in the balance between blood clot formation (coagulation) and dissolution (fibrinolysis), which is mainly activated by thrombin bonded with thrombomodulin (TM). Methods: In this study, the investigation focused on the unique target TAFI of fungi fibrinolytic compound 1 (FGFC1), a novel fibrinolytic compound sourced from the deep sea. In this sense, the regulation of TAFI by FGFC1, in comparison to established TAFI inhibitors such as DS-1040 and PCTI in hPPP, was investigated, which was validated through the molecular docking of FGFC1 to TAFI. The inhibitory effect of FGFC1 on TAFI-mediating coagulation (ex vivo and in vitro) and its fibrinolytic effect (ex vivo) were investigated in hPPP and hCMEC/D3 cells, respectively, followed by SEM. Results: FGFC1 solutions ranging from 0.023 to 0.736 mM effectively inhibited TAFI activation. Notably, the 0.023 mM concentration demonstrated significant suppression, comparable to DS-1040 and PCTI. These inhibitory effects of FGFC1 (0.023–0.368 mM) were further validated through the enhancement in TAFI (TAFIa) activation by fibrins in the coagulum prior to proteolysis, resulting in the cleavage of TAFIa from 33 kDa to 28 kDa. Furthermore, these regulatory effects of FGFC1 on TAFI were demonstrated to have minimal association with TM-mediated control, as confirmed through a molecular docking analysis. FGFC1 (0.023–0.092 mM) was suggested to have obstructive effects on TAFI-mediated coagulation in the hPPP, which was demonstrated by the inhibition of clot aggregation, protein crystallization, and platelet anchoring, as observed through SEM. Simultaneously, FGFC1 (0.023 to 0.368 mM) significantly enhanced TAFI-mediated fibrinolysis, which was also supported by increased levels of t-PA, u-PA, and plasmin. Conclusions: From the above findings, FGFC1 is identified as a novel dual-target bioactive compound participating in blood formation/dissolution that demonstrates anti-coagulation and fibrinolytic effects by regulating TAFI activation, inhibiting TAFIa–fibrin combination, and initiating proteolysis. It also provided convincing evidence that TAFI plays a critical role in thrombolysis as a molecular link between coagulation and fibrinolysis. Furthermore, the application of FGFC1 was indicated as a potential therapeutic strategy in thromboembolic and hemorrhagic diseases. Full article

Systemic sclerosis (SSc) is characterized by a complex interplay of vascular damage, inflammation, and fibrosis, affecting the skin and internal organs. Plasminogen activator inhibitor-1 (PAI-1), a protein encoded by the SERPINE1 gene, is a potential biomarker of SSc because it is primarily involved in fibrinolysis and is associated with the severity of some autoimmune diseases. This study aimed to determine the association between SERPINE1 variant -675 4G/5G and soluble PAI-1 (sPAI-1) levels with the clinical characteristics and risk of SSc in a Mexican population. This cross-sectional study included 56 SSc patients and 114 control subjects (CSs). The variant was genotyped via the PCR–RFLP method and the levels of sPAI-1 were determined using enzyme-linked immunosorbent assays (ELISAs). The -675 4G/5G variant was not associated with SSc risk or sPAI-I levels. However, higher sPAI-1 levels were observed in SSc patients than in CSs (p = 0.045); these levels were significantly correlated with age, platelets, glucose, and serum levels of transforming growth factor (TGF)-β1, 2, and 3. The SERPINE1 -675 4G/5G variant did not show any association with SSc risk or sPAI-I levels. However, our study shows a possible alteration of sPAI-1 in this disease, which could be associated with the fibrotic and thrombotic processes in SSc. Full article

Serine protease inhibitors (serpins) participate in the regulation of inflammation, blood coagulation, and complement activation in humans. This research aimed to identify and characterize such inhibitors of the human liver fluke Opisthorchis viverrini. Parasite proteins that might contribute to the modulation of host physiology are of particular interest, especially as chronic opisthorchiasis increases the risk of developing biliary cancer. BLAST was used to find hypothetical serpins predicted from the parasite genome data. RNA extraction and reverse transcriptase PCR were used to isolate a serpin cDNA and to determine developmental transcript abundance. The evolutionary relation to other trematode serpins was revealed by phylogenetic analysis. Recombinant serpin was expressed in Escherichia coli and used to test the immunoreactivity of human opisthorchiasis sera and the inhibition of human serine proteases. A substantial serpin family with high sequence divergence among the members was found in the genus Opisthorchis. A serpin, different from previously analyzed trematode serpins, was cloned. The transcript was only detected in metacercariae and newly excysted juveniles. Human opisthorchiasis sera showed statistically significant reactivity to recombinant serpin. The serpin caused moderate inhibition of thrombin and low inhibition of kallikrein and chymotrypsin. This parasite serpin could be further evaluated as a diagnostic tool for early infection. Kallikrein and thrombin are involved in fibrinolysis; therefore, further research should explore the effects of the parasite serpin on this process. Full article

Serine protease inhibitors are a superfamily of proteins that regulate various physiological processes including fibrinolysis, inflammation and immune responses. In parasite systems, serpins are believed to play important roles in parasite colonization, inhibition of host immune serine proteases and penetration of defensive barriers. However, serpins are less well characterized in schistosomes. In this study, a Schistosoma mansoni serpin (Smserpin-p46) containing a 1360 base pair open reading frame, was cloned, expressed and functionally characterized. Bioinformatics analysis revealed that Smserpin-p46 contains the key residues, structural domains and motifs characteristic of inhibitory serpins. Gene expression profiling demonstrated stage-specific expression of Smserpin-p46 with the highest expression in adult male worms. Recombinant Smserpin-p46 (rSmserpin-p46) inhibited both human neutrophil cathepsin G and elastase, key serine proteases involved in NETosis, a program for the formation of neutrophil extracellular traps. Using specific rabbit antiserum, Smserpin-p46 was detected in soluble worm antigen preparation and was localized to the adult worm tegument. Cumulatively, the expression of Smserpin-p46 on the parasite tegument and its ability to inhibit proteases involved in NETosis highlights the importance of this serpin in parasite-host interactions and encourages its further investigation as a candidate vaccine antigen for the control of schistosomiasis. Full article

Plasminogen activator inhibitor-1 (PAI-1) has a significant role in fibrinolysis, atherogenesis, cellular senescence, and chronic inflammation. OSA (obstructive sleep apnea) leads to increased PAI-1 levels and the development of cardiovascular disease (CVD). The aim of this study was to determine the effects of CPAP therapy on coagulation parameters and PAI-1 in patients with severe OSA. This prospective, controlled study enrolled 57 patients who were newly diagnosed with severe OSA, 37 of whom had had good CPAP adherence after 6 months of therapy (usage of the device for at least 4 h per night), and their data were analyzed. The analysis showed a statistically significant increase in D-dimer values before CPAP therapy (415 (316.5–537.5)) vs. after therapy (499 (327–652)), p = 0.0282, and a decrease in fibrinogen values (3.665 ± 0.752 before CPAP therapy vs. 3.365 ± 0.771 after therapy, p = 0.0075)). PAI-1 concentration values before and after CPAP therapy did not differ significantly (17.35 ± 7.01 ng/mL before CPAP therapy vs. 17.42 ± 6.99 ng/mL after therapy, p = 0.9367). This study shows a tendency for fibrinolytic capacity to improve in patients with OSA after CPAP therapy, although PAI-1 levels did not differ significantly. Full article