"Super" SERPINs-A stabilizing force against fibrinolysis in thromboinflammatory conditions

Comprehensive review of thrombophilia: pathophysiology, prevalence, risk factors, and molecular diagnosis

Thrombophilia, characterized by an imbalance between fibrinolysis and coagulation leading to inappropriate blood clotting, is a significant medical condition. The CDC has designated it as an underdiagnosed, serious, and potentially preventable disorder, contributing to an estimated 600,000-900,000 cases and 100,000 deaths annually in the United States. These figures surpass the combined annual mortality of AIDS, breast cancer, and motor vehicle accidents. The pathogenesis of thrombophilia involves complex interactions between genetic predispositions, such as mutations in Factor V Leiden, Factor II, MTHFR, and Serpine-1, and environmental factors, including unhealthy lifestyles, prolonged hospitalization, obesity, and cancer. Prevalence of specific genetic mutations varies across populations. Additional risk factors include age, family history, and pregnancy, with recent attention to increased susceptibility in SARS-CoV-2 infection. While molecular diagnostic techniques are available, there remains a need for robust, cost-effective, and accurate screening methods for large populations. This systematic review provides an updated overview of thrombophilia, encompassing pathophysiology, epidemiology, genetic and environmental risk factors, coagulation cascade, population-specific mutation prevalence, and diagnostic approaches. By synthesizing clinical and molecular evidence, this review aims to guide researchers, hematologists, and clinicians in the diagnosis and management of thrombophilia.

Targeting Matrix Metalloproteinase-1, Matrix Metalloproteinase-7, and Serine Protease Inhibitor E1: Implications in preserving lung vascular endothelial integrity and immune modulation in COVID-19

BACKGROUND

SARS-CoV-2 disrupts lung vascular endothelial integrity, contributing to severe COVID-19 complications. However, the molecular mechanisms driving endothelial dysfunction remain underexplored, and targeted therapeutic strategies are lacking.

OBJECTIVE

This study investigates Naringenin-7-O-glucoside (N7G) as a multi-target therapeutic candidate for modulating vascular integrity and immune response by inhibiting MMP1, MMP7, and SERPINE1-key regulators of extracellular matrix (ECM) remodeling and inflammation.

METHODS & RESULTS

RNA-seq analysis of COVID-19 lung tissues identified 17 upregulated N7G targets, including MMP1, MMP7, and SERPINE1, with the latter exhibiting the highest expression. PPI network analysis linked these targets to ECM degradation, IL-17, HIF-1, and AGE-RAGE signaling pathways, and endothelial dysfunction. Disease enrichment associated these genes with idiopathic pulmonary fibrosis and asthma. Molecular docking, 200 ns MD simulations (triplicate), and MMGBSA calculations confirmed N7G's stable binding affinity to MMP1, MMP7, and SERPINE1. Immune profiling revealed increased neutrophils and activated CD4+ T cells, alongside reduced mast cells, NK cells, and naïve B cells, indicating immune dysregulation. Correlation analysis linked MMP1, MMP7, and SERPINE1 to distinct immune cell populations, supporting N7G's immunomodulatory role.

CONCLUSION

These findings suggest that N7G exhibits multi-target therapeutic potential by modulating vascular integrity, ECM remodeling, and immune dysregulation, positioning it as a promising candidate for mitigating COVID-19-associated endothelial dysfunction.

Recent Advances in Pathogenesis and Anticoagulation Treatment of Sepsis-Induced Coagulopathy

Coagulopathy in sepsis is common and is associated with high mortality. Although immunothrombosis is necessary for infection control, excessive thrombus formation can trigger a systemic thrombo-inflammatory response. Immunothrombosis plays a core role in sepsis-induced coagulopathy, and research has revealed a complex interplay between inflammation and coagulation. Different mechanisms underlying sepsis-related coagulopathy are discussed, including factors contributing to the imbalance of pro- and anticoagulation relevant to endothelial cells. The potential therapeutic implications of anticoagulants on these mechanisms are discussed. This review contributes to our understanding of the pathogenesis of coagulopathy in patients with sepsis. Recent studies suggest that endothelial cells play an important role in immunoregulation and hemostasis. Meanwhile, the non-anticoagulation effects of anticoagulants, especially heparin, which act in the pathogenesis of coagulopathy in septic patients, have been partially revealed. We believe that further insights into the pathogenesis of sepsis-induced coagulopathy will help physicians evaluate patient conditions effectively, leading to advanced early recognition and better decision-making in the treatment of sepsis.

The foundation for investigating factor XI as a target for inhibition in human cardiovascular disease

Anticoagulant therapy is a mainstay in the management of patients with cardiovascular disease and related conditions characterized by a heightened risk for thrombosis. Acute coronary syndrome, chronic coronary syndrome, ischemic stroke, and atrial fibrillation are the most common. In addition to their proclivity for thrombosis, each of these four conditions is also characterized by local and systemic inflammation, endothelial/endocardial injury and dysfunction, oxidative stress, impaired tissue-level reparative capabilities, and immune dysregulation that plays a critical role in linking molecular events, environmental triggers, and phenotypic expressions. Knowing that cardiovascular disease and thrombosis are complex and dynamic, can the scientific community identify a common pathway or specific point of interface susceptible to pharmacological inhibition or alteration that is likely to be safe and effective? The contact factors of coagulation may represent the proverbial "sweet spot" and are worthy of investigation. The following review provides a summary of the fundamental biochemistry of factor XI, its biological activity in thrombosis, inflammation, and angiogenesis, new targeting drugs, and a pragmatic approach to managing hemostatic requirements in clinical trials and possibly day-to-day patient care in the future.

The Crystal Structure of the Michaelis-Menten Complex of C1 Esterase Inhibitor and C1s Reveals Novel Insights into Complement Regulation

The ancient arm of innate immunity known as the complement system is a blood proteolytic cascade involving dozens of membrane-bound and solution-phase components. Although many of these components serve as regulatory molecules to facilitate controlled activation of the cascade, C1 esterase inhibitor (C1-INH) is the sole canonical complement regulator belonging to a superfamily of covalent inhibitors known as serine protease inhibitors (SERPINs). In addition to its namesake role in complement regulation, C1-INH also regulates proteases of the coagulation, fibrinolysis, and contact pathways. Despite this, the structural basis for C1-INH recognition of its target proteases has remained elusive. In this study, we present the crystal structure of the Michaelis-Menten (M-M) complex of the catalytic domain of complement component C1s and the SERPIN domain of C1-INH at a limiting resolution of 3.94 Å. Analysis of the structure revealed that nearly half of the protein/protein interface is formed by residues outside of the C1-INH reactive center loop. The contribution of these residues to the affinity of the M-M complex was validated by site-directed mutagenesis using surface plasmon resonance. Parallel analysis confirmed that C1-INH-interfacing residues on C1s surface loops distal from the active site also drive affinity of the M-M complex. Detailed structural comparisons revealed differences in substrate recognition by C1s compared with C1-INH recognition and highlight the importance of exosite interactions across broader SERPIN/protease systems. Collectively, this study improves our understanding of how C1-INH regulates the classical pathway of complement, and it sheds new light on how SERPINs recognize their cognate protease targets.

The fatal contribution of serine protease-related genetic variants to COVID-19 outcomes

Introduction

Serine proteases play a critical role during SARS-CoV-2 infection. Therefore, polymorphisms of transmembrane protease serine 2 (TMPRSS2) and serpine family E member 1 (SERPINE1) could help to elucidate the contribution of variability to COVID-19 outcomes.

Methods

To evaluate the genetic variants of the genes previously associated with COVID-19 outcomes, we performed a cross-sectional study in which 1536 SARS-CoV-2-positive participants were enrolled. TMPRSS2 (rs2070788, rs75603675, rs12329760) and SERPINE1 (rs2227631, rs2227667, rs2070682, rs2227692) were genotyped using the Open Array Platform. The association of polymorphisms with disease outcomes was determined by logistic regression analysis adjusted for covariates (age, sex, hypertension, type 2 diabetes, and obesity).

Results

According to our codominant model, the GA genotype of rs2227667 (OR=0.55; 95% CI = 0.36-0.84; p=0.006) and the AG genotype of rs2227667 (OR=0.59; 95% CI = 0.38-0.91; p=0.02) of SERPINE1 played a protective role against disease. However, the rs2227692 T allele and TT genotype SERPINE1 (OR=1.45; 95% CI = 1.11-1.91; p=0.006; OR=2.08; 95% CI = 1.22-3.57; p=0.007; respectively) were associated with a decreased risk of death. Similarly, the rs75603675 AA genotype TMPRSS2 had an OR of 1.97 (95% CI = 1.07-3.6; p=0.03) for deceased patients. Finally, the rs2227692 T allele SERPINE1 was associated with increased D-dimer levels (OR=1.24; 95% CI = 1.03-1.48; p=0.02).

Discussion

Our data suggest that the rs75603675 TMPRSS2 and rs2227692 SERPINE1 polymorphisms are associated with a poor outcome. Additionally, rs2227692 SERPINE1 could participate in hypercoagulable conditions in critical COVID-19 patients, and this genetic variant could contribute to the identification of new pharmacological targets and treatment strategies to block the inhibition of TMPRSS2 entry into SARS-CoV-2.

PAI-1 as a critical factor in the resolution of sepsis and acute kidney injury in old age

Elevated plasma levels of plasminogen activator inhibitor type 1 (PAI-1) are documented in patients with sepsis and levels positively correlate with disease severity and mortality. Our prior work demonstrated that PAI-1 in plasma is positively associated with acute kidney injury (AKI) in septic patients and mice. The objective of this study was to determine if PAI-1 is causally related to AKI and worse sepsis outcomes using a clinically-relevant and age-appropriate murine model of sepsis. Sepsis was induced by cecal slurry (CS)-injection to wild-type (WT, C57BL/6) and PAI-1 knockout (KO) mice at young (5-9 months) and old (18-22 months) age. Survival was monitored for at least 10 days or mice were euthanized for tissue collection at 24 or 48 h post-insult. Contrary to our expectation, PAI-1 KO mice at old age were significantly more sensitive to CS-induced sepsis compared to WT mice (24% vs. 65% survival, p = 0.0037). In comparison, loss of PAI-1 at young age had negligible effects on sepsis survival (86% vs. 88% survival, p = 0.8106) highlighting the importance of age as a biological variable. Injury to the kidney was the most apparent pathological consequence and occurred earlier in aged PAI-1 KO mice. Coagulation markers were unaffected by loss of PAI-1, suggesting thrombosis-independent mechanisms for PAI-1-mediated protection. In summary, although high PAI-1 levels are clinically associated with worse sepsis outcomes, loss of PAI-1 rendered mice more susceptible to kidney injury and death in a CS-induced model of sepsis using aged mice. These results implicate PAI-1 as a critical factor in the resolution of sepsis in old age.