Theoretical study of the dimerization of aqueous beryllium cations

Reaction mechanism conversion induced by the contest of nucleophile and leaving group

Direct dynamic simulations have been employed to investigate the OH^- + CH₃Cl reaction with the chosen B3LYP/aug-cc-pVDZ method. The calculated rate coefficient for the bimolecular nucleophilic substitution reaction (S_N2), 1.0 × 10^-9 cm³ mol^-1 s^-1 at 300 K, agrees well with the experimental result of (1.3-1.6) × 10^-9 cm³ mol^-1 s^-1. The simulations reveal that the majority of the S_N2 reactions are temporarily trapped in the hydrogen-bonded complex at E_coll = 0.89 kcal mol^-1. Importantly, the influences of the leaving group and nucleophile have been discussed by comparisons of X^- + CH₃Y (X = F, OH; Y = Cl, I) reactions. For the X = F^- reactions, the reaction probability of S_N2 increases along the increased leaving group ability Cl < I, suggesting that the thermodynamic factor plays a key role. The indirect mechanisms were found to be dominant for both reactions. In contrast, for X = OH^-, the fraction of S_N2 drops with the enhanced leaving group ability. In particular, a dramatic transition occurs for the dominant atomic reaction mechanisms, i.e., from complex-mediated indirect to direct, implying an interesting contest between the leaving group and the nucleophile and the importance of the dynamic factors, i.e., the dipole moment, steric hindrance, and electronegativity.

HMGB1-Neutralizing IgM Antibody Is a Normal Component of Blood Plasma

Extracellular high-mobility group box 1 (HMGB1) is a prototypic damage-associated molecular pattern. Although a homeostatic level of extracellular HMGB1 may be beneficial for immune defense, tissue repair, and tissue regeneration, excessive HMGB1 is linked to inflammatory diseases. This prompts an intriguing question: how does a healthy body control the level of extracellular HMGB1? In this study, in the plasma of both healthy humans and healthy mice, we have identified an anti-HMGB1 IgM autoantibody that neutralizes extracellular HMGB1 via binding specifically to a 100% conserved epitope, namely HMW4 (HMGB1_98-112). In mice, this anti-HMW4 IgM is produced by peritoneal B-1 cells, and concomitant triggering of their BCR and TLR4 by extracellular HMGB1 stimulates the production of anti-HMW4 IgM. The ability of extracellular HMGB1 to induce its own neutralizing Ab suggests a feedback loop limiting the level of this damage-associated molecular pattern in a healthy body.

Microplate-based Assay for Screening of Advanced Glycation End Products Binding to Its Receptor

Advanced Glycation End products (AGEs) are a group of amino-acid modifications produced with sugars or di-carbonyls. Some AGEs are known to affect health through binding to the receptor of AGEs (RAGE). Here, we propose a method for screening RAGE-binding AGEs by a competitive assay using purified RAGE and AGEs-specific antibody. This method has clarified that at least carboxyethyl lysine and pentosidine among methylglyoxal-derived AGEs are involved in RAGE binding, suggesting that this would be a promising method for classifying RAGE-binding AGEs.

HMBG1 as a Driver of Inflammatory and Immune Processes in the Pathogenesis of Ocular Diseases

High-mobility group box 1 (HMGB1) is a nuclear protein that can also act as an extracellular trigger of inflammation, proliferation, and migration in eye diseases. It induces signaling pathways by binding to the receptor for advanced glycation end products (RAGE) and Toll-like receptors (TLRs) 2, 4, and 9. This proinflammatory activity is considered to be important in the pathogenesis of a wide range of ocular diseases resulting from hemodynamic changes, presence of neovascular endothelial cells, secretion of intraocular immune factors or inflammation, and apoptosis of retinal cell layers. Further work is needed to elucidate in detail how HMGB1 contributes to ocular disease and how its damaging activity can be modulated. In this review, we summarize current knowledge on HMGB1 as a ligand that can evoke inflammation and immune responses in ocular diseases.

Critical Interactions between Immunogenic Cancer Cell Death, Oncolytic Viruses, and the Immune System Define the Rational Design of Combination Immunotherapies

Oncolytic viruses (OVs) are multimodal cancer therapeutics, with one of their dominant mechanisms being in situ vaccination. There is a growing consensus that optimal cancer therapies should generate robust tumor-specific immune responses. Immunogenic cell death (ICD) is a paradigm of cellular demise culminating in the spatiotemporal release of danger-associated molecular patterns that induce potent anticancer immunity. Alongside traditional ICD inducers like anthracycline chemotherapeutics and radiation, OVs have emerged as novel members of this class of therapeutics. OVs replicate in cancers and release tumor Ags, which are perceived as dangerous because of simultaneous expression of pathogen-associated molecular patterns that activate APCs. Therefore, OVs provide the target Ags and danger signals required to induce adaptive immune responses. This review discusses why OVs are attractive candidates for generating ICD, biological barriers limiting their success in the clinic, and groundbreaking strategies to potentiate ICD and antitumor immunity with rationally designed OV-based combination therapies.

The role of HMGB1 in BMSC transplantation for treating MODS in rats

The effect of bone marrow mesenchymal stem cells (BMSCs) in treatment for multiple organ dysfunction syndrome (MODS) remains unknown and the mechanism is still unclear. Therefore, the goal of this study is to investigate the effects of intracellular high mobility group box 1 protein (HMGB1) on BMSCs treating for MODS. The rats were given 15% blood loss plus 1 mg/kg lipopolysaccharide (LPS) via lower extremity superficial venous, then randomly allocated into four groups: sham group, MODS group, MODS plus BMSC group, MODS plus ethyl pyruvate (EP) group, MODS plus BMSCs plus EP group. Twenty-four hours later, rats in groups were sacrificed and then the blood and tissues were collected to evaluate the changes of tissue histopathology, cell apoptosis, inflammation level and organ function. The HGMB1 expression was monitored by RT-qPCR and Western blot. The expression of RAGE/TLR2/TLR4 and NF-κB at the protein levels was also assessed. BMSCs and/or EP exhibits an outstanding protective effect against LPS-induced histopathological injury by improving cell apoptosis, inflammatory response and the organ dysfunction but no effect on BMSC homing to the injury site. Moreover, BMSCs and/or EP inhibited LPS-induced upregulation of HMGB1, RAGE, TLR2 and TLR4 expression at protein levels and compromised p65 phosphorylation in the rat model of MODS. These findings suggest that HMGB1 is involved in BMSC treatment for MODS, through regulation of the TLR2, TLR4-mediated NF-κB signal pathway. It suggests that HMGB1 is an attractive potential target for the development of new therapeutic strategies for MODS.

Deep vein thrombosis in mice is regulated by platelet HMGB1 through release of neutrophil-extracellular traps and DNA

Venous thromboembolic (VTE) disease, consisting of deep venous thrombosis (DVT) and pulmonary embolism (PE) is a leading cause of morbidity and mortality. Current prophylactic measures are insufficient to prevent all occurrence in part due to an incomplete understanding of the underlying pathophysiology. Mounting evidence describes interplay between activation of the innate immune system and thrombus development. Recent work has demonstrated that platelet release of HMGB1 leads to increased microvascular complications following injury. Additionally, platelet HMGB1 was found to enhance DVT and increase the formation of neutrophil extracellular traps (NETs), although the role of HMGB1 induced NET release in thrombosis remains unexplored. Utilizing a transgenic mouse lacking HMGB1 specifically from platelets and megakaryocytes we now demonstrate the specific role of platelet-derived HMGB1 in acute and subacute/chronic venous thrombosis. Platelets account for the majority of circulating HMGB1 and HMGB1 deposition within the developing clot. The pro-thrombotic effect of platelet-derived HMGB1 is mediated through enhanced neutrophil recruitment, NET formation and specifically release of extracellular DNA during NET formation. Taken together, these data suggest that platelet HMGB1 mediated NET release is a primary regulator of DVT formation in mice.

Cysteine redox state plays a key role in the inter-domain movements of HMGB1: a molecular dynamics simulation study

We have modelled and simulated different states of HMGB1, suggesting that the fully reduced HMGB1 maintains the inter-domain movements during the activity.

Structures and formation mechanisms of aquo/hydroxo oligomeric beryllium in aqueous solution: a density functional theory study

The structures and formation mechanisms of a wide variety of aquo/hydroxo oligomeric beryllium clusters were investigated using density functional theory. The structural parameters of beryllium clusters were found to vary regularly with the stepwise substitution of bound water molecules in the inner coordination sphere by hydroxyl groups. According to the Gibbs free energies deduced from SMD solvation model computations, unhydrolyzed oligomeric beryllium species are the most favorable products of polymerization, independent of the degrees of hydrolysis of the reactants. Simulation of the formation processes of oligomeric beryllium showed that polymerization, in essence, involves the nucleophilic attack of a terminal hydroxyl group in one BeO4 tetrahedron on the beryllium center in another BeO4 tetrahedron, leading to the bridging of two BeO4 tetrahedrons by a hydroxyl group.