Bioactive lipid regulation of platelet function, hemostasis, and thrombosis

A macromolecular cross-linked alginate aerogel with excellent concentrating effect for rapid hemostasis

Alginate-based materials present promising potential for emergency hemostasis due to their excellent properties, such as procoagulant capability, biocompatibility, low immunogenicity, and cost-effectiveness. However, the inherent deficiencies in water solubility and mechanical strength pose a threat to hemostatic efficiency. Here, we innovatively developed a macromolecular cross-linked alginate aerogel based on norbornene- and thiol-functionalized alginates through a combined thiol-ene cross-linking/freeze-drying process. The resulting aerogel features an interconnected macroporous structure with remarkable water-uptake capacity (approximately 9000 % in weight ratio), contributing to efficient blood absorption, while the enhanced mechanical strength of the aerogel ensures stability and durability during the hemostatic process. Comprehensive hemostasis-relevant assays demonstrated that the aerogel possessed outstanding coagulation capability, which is attributed to the synergistic impacts on concentrating effect, platelet enrichment, and intrinsic coagulation pathway. Upon application to in vivo uncontrolled hemorrhage models of tail amputation and hepatic injury, the aerogel demonstrated significantly superior performance compared to commercial alginate hemostatic agent, yielding reductions in clotting time and blood loss of up to 80 % and 85 %, respectively. Collectively, our work illustrated that the alginate porous aerogel overcomes the deficiencies of alginate materials while exhibiting exceptional performance in hemorrhage, rendering it an appealing candidate for rapid hemostasis.

One-Year Effects of High-Intensity Statin on Bioactive Lipids: Findings From the JUPITER Trial

BACKGROUND

Statin effects extend beyond low-density lipoprotein cholesterol reduction, potentially modulating the metabolism of bioactive lipids (BALs), crucial for biological signaling and inflammation. These bioactive metabolites may serve as metabolic footprints, helping uncover underlying processes linked to pleiotropic effects of statins and yielding a better understanding of their cardioprotective properties. This study aimed to investigate the impact of high-intensity statin therapy versus placebo on plasma BALs in the JUPITER trial (Justification for the Use of Statins in Prevention: an Intervention Trial Evaluating Rosuvastatin; NCT00239681), a randomized primary prevention trial involving individuals with low-density lipoprotein cholesterol <130 mg/dL and high-sensitivity C-reactive protein ≥2 mg/L.

METHODS

Using a nontargeted mass spectrometry approach, over 11 000 lipid features were assayed from baseline and 1-year plasma samples from cardiovascular disease noncases from 2 nonoverlapping nested substudies: JUPITERdiscovery (n=589) and JUPITERvalidation (n=409). The effect of randomized allocation of rosuvastatin 20 mg versus placebo on BALs was examined by fitting a linear regression with delta values (∆=year 1-baseline) adjusted for age and baseline levels of each feature. Significant associations in discovery were analyzed in the validation cohort. Multiple comparisons were adjusted using 2-stage overall false discovery rate.

RESULTS

We identified 610 lipid features associated with statin randomization with significant replication (overall false discovery rate, <0.05), including 26 with annotations. Statin therapy significantly increased levels of 276 features, including BALs with anti-inflammatory activity and arterial vasodilation properties. Concurrently, 334 features were significantly lowered by statin therapy, including arachidonic acid and proinflammatory and proplatelet aggregation BALs. By contrast, statin therapy reduced an eicosapentaenoic acid-derived hydroxyeicosapentaenoic acid metabolite, which may be related to impaired glucose metabolism. Additionally, we observed sex-related differences in 6 lipid metabolites and 6 unknown features.

CONCLUSIONS

Statin allocation was significantly associated with upregulation of BALs with anti-inflammatory, antiplatelet aggregation and antioxidant properties and downregulation of BALs with proinflammatory and proplatelet aggregation activity, supporting the pleiotropic effects of statins beyond low-density lipoprotein cholesterol reduction.

Thirty years with three-dimensional structures of lipoxygenases

The X-ray crystal structures of soybean lipoxygenase (LOX) and rabbit 15-LOX were reported in the 1990s. Subsequent 3D structures demonstrated a conserved U-like shape of the substrate cavities as reviewed here. The 8-LOX:arachidonic acid (AA) complex showed AA bound to the substrate cavity carboxylate-out with C10 at 3.4 Å from the iron metal center. A recent cryo-electron microscopy (EM) analysis of the 12-LOX:AA complex illustrated AA in the same position as in the 8-LOX:AA complex. The 15- and 12-LOX complexes with isoenzyme-specific inhibitors/substrate mimics confirmed the U-fold. 5-LOX oxidizes AA to leukotriene A4, the first step in biosynthesis of mediators of asthma. The X-ray structure showed that the entrance to the substrate cavity was closed to AA by Phe and Tyr residues of a partly unfolded α2-helix. Recent X-ray analysis revealed that soaking with inhibitors shifted the short α2-helix to a long and continuous, which opened the substrate cavity. The α2-helix also adopted two conformations in 15-LOX. 12-LOX dimers consisted of one closed and one open subunit with an elongated α2-helix. 13C-ENDOR-MD computations of the 9-MnLOX:linoleate complex showed carboxylate-out position with C11 placed 3.4 ± 0.1 Å from the catalytic water. 3D structures have provided a solid ground for future research.

Preparing to strike: Acute events in signaling by the serpentine receptor for thromboxane A2

Over the last two decades, awareness of the (patho)physiological roles of thromboxane A₂ signaling has been greatly extended. From humble beginnings as a short-lived stimulus that activates platelets and causes vasoconstriction to a dichotomous receptor system involving multiple endogenous ligands capable of modifying tissue homeostasis and disease generation in almost every tissue of the body. Thromboxane A₂ receptor (TP) signal transduction is associated with the pathogenesis of cancer, atherosclerosis, heart disease, asthma, and host response to parasitic infection amongst others. The two receptors mediating these cellular responses (TPα and TPβ) are derived from a single gene (TBXA2R) through alternative splicing. Recently, knowledge about the mechanism(s) of signal propagation by the two receptors has undergone a revolution in understanding. Not only have the structural relationships associated with G-protein coupling been established but the modulation of that signaling by post-translational modification to the receptor has come sharply into focus. Moreover, the signaling of the receptor unrelated to G-protein coupling has become a burgeoning field of endeavor with over 70 interacting proteins currently identified. These data are reshaping the concept of TP signaling from a mere guanine nucleotide exchange factors for Gα activation to a nexus for the convergence of diverse and poorly characterized signaling pathways. This review summarizes the advances in understanding in TP signaling, and the potential for new growth in a field that after almost 50 years is finally coming of age.