Exploring the Mechanisms of Anti-Aβ42 Aggregation Activity of Walnut-derived Peptides using Transcriptomics and Proteomics in vitro

Inhibiting β-amyloid (Aβ) aggregation is of significance in finding potential candidates for Alzheimer’s disease (AD) treatment. Accumulating evidence suggests that nutrition is important for improving cognition and reducing AD risk. Walnut has been widely used as a functional food for brain health; however the underlying mechanisms remain unknown. Here, we investigated the molecular level alteration in Arctic mutant Aβ42 induced aggregation cell model by RNA-seq and iTRAQ approaches after walnut-derived peptides Pro-Pro-Lys-Asn-Trp (PW5) and Trp-Pro-Pro-Lys-Asn (WN5) interventions. PW5 or WN5 could significantly decrease abnormal Aβ42 aggregates. However, resultant alterations in transcriptome (substantially unchanged) were inconsistent with proteomic data (marked change). Proteomic analysis revealed 184 and 194 differentially expressed proteins unique to PW5 and WN5 treatment, respectively, for inhibiting Aβ42 protein production or increasing protein degradation via the mismatch repair pathways. Our study provides new insights into the effectiveness of food-derived peptides for anti-Aβ42 aggregation in AD.

The role of disorders in the functional activity of platelets in the pathogenesis of microcirculatory disorders in patients with catarrhal gingivitis

A comprehensive examination of patients with chronic catarrhal gingivitis and with exacerbation of chronic catarrhal gingivitis with the inclusion of indicators of the microcirculatory link of the hemostasis system was carried out. In patients with exacerbation of chronic catarrhal gingivitis, platelet aggregation activity is increased compared to that in healthy individuals. This is accompanied by a statistically significant increase in the maximum degree of aggregation, a change in the time to reach the maximum degree of platelet aggregation Key words: platelet aggregation, catarrhal gingivitis, exacerbation of chronic catarrhal gingivitis.

Morphofunctional assessment of platelet activity correction in hyperbaric blood oxygenation

100 patients with functional class II-III exertional angina were examined. The subjects underwent a 10-day course of hyperbaric oxygenation (HBO) in the 1.2 ATA mode for 40 minutes, against the background of standard therapy for coronary heart disease (IHD). Before and after HBO, the platelet link of hemostasis and the elastic properties of the platelet membrane were assessed. Assessment of the effect of the HBO course on the functional state of platelets, depending on their aggregation activity, showed that in patients with initially normal platelet aggregation, there is a tendency to a decrease in spontaneous aggregation, in contrast to patients with initial hypoaggregation, HBO promoted a significant increase in spontaneous aggregation. The use of a 10-day course of HBO was accompanied by a reaction of reducing the elasticity of the platelet biomembrane. Key words: aggregation; atomic force microscopy; platelet membrane; hyperbaric oxygenation.

A Spider Silk-derived Solubility Domain Inhibits Nuclear and Cytosolic Protein Aggregation in Human Cells

Due to the inherent toxicity of protein aggregates, the propensity of natural, functional amyloidogenic proteins to aggregate must be tightly controlled to avoid negative consequences on cellular viability. The importance of controlled aggregation in biological processes is illustrated by spidroins, which are functional amyloidogenic proteins that form the basis for spider silk. Premature aggregation of spidroins is prevented by the N-terminal NT domain. Here we explored the potential of the engineered, spidroin-based NT* domain in preventing protein aggregation in the intracellular environment of human cells. We show that the NT* domain increases the soluble pool of a reporter protein carrying a ligand-regulatable aggregation domain. Interestingly, the NT* domain prevents the formation of aggregates independent of its position in the aggregation-prone protein. The ability of the NT* domain to inhibit ligand-regulated aggregation was evident both in the cytosolic and nuclear compartments, which are both highly relevant for human disorders linked to non-physiological protein aggregation. We conclude that the spidroin-derived NT* domain has a generic anti-aggregation activity, independent of position or subcellular location, that is also active in human cells and propose that the NT* domain can potentially be exploited in controlling protein aggregation of disease-associated proteins.

The influence of metabolic activity of platelets on sensitivity to Acetylsalicylic acid in patients with coronary heart disease

Background Acetylsalicylic acid (ASA) is used to reduce the risk of shunt occlusion after coronary artery bypass grafting (CABG). From 5% to 60% of CHD patients do not respond to ASA. This phenomenon was defined as ASA resistance. The functional activity of platelets is largely determined by the state of their metabolism. Methods The venous blood samples were acquired from 66 patients with CHD before CABG, on the first day after surgery, and on the 8–10th day after surgery. The aggregometry was carried out for all participants by an optical aggregometer with 1 mM of arachidonic acid (AA) and 5 mM Adenosinediphosphate (ADP). Resistance to ASA was determined at the level of platelet aggregation with AA over 20% on ASA therapy or over 20% after platelet incubation with ASA in vitro before CABG. Patients were divided into ASA sensitive (sASA) and ASA resistant (rASA) groups. The level of synthesis of primary and secondary reactive oxygen species (ROS) by platelets was determined using chemiluminescent analysis. We investigated the overall level of radical synthesis from the values of Imax and S (area under the chemiluminescence curve), which, respectively, characterizes the maximum synthesis per unit time and the total amount of radical. The kinetics of ROS synthesis was characterized by Tmax (time to reach the maximum for the chemiluminescent curve). The activity of NAD- and NADP-dependent dehydrogenases in platelets was determined by the bioluminescent method. Results It was found that the aggregation activity of platelets depended on the sensitivity of CHD patients to ASA and decreased during postoperative ASA therapy. The most pronounced differences in metabolic parameters of platelets in sASA and rASA patients were detected by Nox2 activity. Platelet aggregation activity was correlated with platelet Nox2 activity only in sASA patients and only before CABG. The level of AA-induced platelet aggregation with the addition of ASA in sASA patients before CABG was negatively correlated with the Imax of ADP-induced lucigenin-enhanced (r=−0.27, p=0.046) and S of spontaneous luminol-enhanced (r=−0.31, p=0.022) platelet chemiluminescence. Patients with rASA before CABG had positive correlations of AA-induced aggregation with S of spontaneous (r=0.63, p=0.029) as well as Imax (r=0.85, p<0.001) and S (r=0.87, p<0.001) of ADP-induced luminol-enhanced chemiluminescence of platelets. Therefore, the absence of correlations between platelet aggregation activity and Nox2 activity was determined by ASA resistance and postoperative ASA therapy. The synthesis of secondary ROS (Table) by platelets of CHD patients did not depend on the sensitivity of patients to ASA but increased during postoperative treatment with ASA. The activity of NAD(P)-dependent dehydrogenases in platelets did not differ in sASA and rASA patients with CHD. Conclusions Metabolic Activity of Platelets could influence on resistance to ASA in Patients with CHD. FUNDunding Acknowledgement Type of funding sources: Public grant(s) – National budget only. Main funding source(s): The reported study was funded by Russian Foundation for Basic Research, Government of Krasno-yarsk Territory, Krasnoyarsk Regional Fund of Science to the research project: “Antiplatelet therapy personification in patients with coronary heart disease (CHD) depending on the level of P-selectin gene expression, the intensity of intercellular interaction and inflammation”

Immunological and hemostasiological aspects of pathogenesis of obliterating atherosclerosis of arteries of the lower extremities

Objectives to study the changes in the immunological status and hemostatic system in patients with obliterating atherosclerosis of the lower limb arteries with the damage to the femoral-popliteal-tibial segment. Material and methods. A comprehensive study of the cytokine status and hemostatic system in patients with obliterating atherosclerosis of lower limb arteries with lesions of the femoral-popliteal tibia segment was carried out. Results. The progressive course of obliterating atherosclerosis is often associated with an increased content of cytokines (IL-1, IL-6, IL-8, TNF), as well as with the phenomena of hypercoagulation (increased platelet aggregation activity, shortened APTT, CT, TT, increased fibrinogen content), SFMCs, D-dimer). Conclusion. The study of the immunological status and hemostatic system should be performed in all patients with obliterating atherosclerosis of the lower limb arteries in order to adequately medically correct and prevent postoperative complications.

Experimental Study of the Effect of Photobiomodulation Therapy on the Regulation of the Healing Process of Chronic Wounds

Currently, wound treatment is an urgent task of medicine around the world. In the process of wound healing, various types of cells are involved under the control and regulation of cytokines and growth factors. Disruption of the synchronization process between the various types of cells and intercellular mediators involved in the restoration of tissue damage can lead to impaired healing and the development of chronic wounds. Photobiomodulation (PBM) therapy promotes platelet activation and aggregation, reduces inflammation and oxidative stress, and accelerates cell migration and proliferation. PBM also induces the production of the extracellular matrix and the release of key growth factors, thereby improving tissue regeneration and accelerating wound healing. The aim of our work was to study the effect of photobiomodulation therapy on the regulation of reparative processes in chronic wounds monitored by biomarkers and platelet aggregation activity. 54 Wistar rats were divided into three groups. Intact animals were not manipulated. In animals of the control and experimental groups, a chronic wound was simulated by reproducing the conditions of local hypoxia and microcirculation disorders. The wounds of the experimental group received PBM therapy. The device Lika-therapist M (Ukraine) was used in a continuous mode at a wavelength of 660 nm, an output power of 10 mW, and an energy density of 1 J/cm2. The wounds of the animals in the control group were treated with sham. The animals were euthanized on days 3, 7, 14, and 28 after the surgery (6 animals, each from the control and experimental groups). Measurements of the levels of interleukin-6 (IL-6), interleukin-10 (IL-10), tumor necrosis factor alpha (TNF-α), the basic fibroblast growth factor (bFGF), and reactive oxygen species (ROS) were carried out by ELISA. Results revealed the multidirectional effect of PBM therapy on the expression of the studied biomarkers. The results of the histological examination indicated a positive effect of PBM therapy with the applied parameters on the repair processes of chronic wounds. We concluded that the use of PBM therapy made it possible to regulate disturbances in reparative processes by modulating ROS, cytokines, and platelet aggregation activity.

Chemoinformatics Analyses of Tau Ligands Reveal Key Molecular Requirements for the Identification of Potential Drug Candidates against Tauopathies

Tau is a highly soluble protein mainly localized at a cytoplasmic level in the neuronal cells, which plays a crucial role in the regulation of microtubule dynamic stability. Recent studies have demonstrated that several factors, such as hyperphosphorylation or alterations of Tau metabolism, may contribute to the pathological accumulation of protein aggregates, which can result in neuronal death and the onset of a number of neurological disorders called Tauopathies. At present, there are no available therapeutic remedies able to reduce Tau aggregation, nor are there any structural clues or guidelines for the rational identification of compounds preventing the accumulation of protein aggregates. To help identify the structural properties required for anti-Tau aggregation activity, we performed extensive chemoinformatics analyses on a dataset of Tau ligands reported in ChEMBL. The performed analyses allowed us to identify a set of molecular properties that are in common between known active ligands. Moreover, extensive analyses of the fragment composition of reported ligands led to the identification of chemical moieties and fragment combinations prevalent in the more active compounds. Interestingly, many of these fragments were arranged in recurring frameworks, some of which were clearly present in compounds currently under clinical investigation. This work represents the first in-depth chemoinformatics study of the molecular properties, constituting fragments and similarity profiles, of known Tau aggregation inhibitors. The datasets of compounds employed for the analyses, the identified molecular fragments and their combinations are made publicly available as supplementary material.

Generalizable Compositional Features Influencing the Proteostatic Fates of Polar Low-Complexity Domains

Protein aggregation is associated with a growing list of human diseases. A substantial fraction of proteins in eukaryotic proteomes constitutes a proteostasis network—a collection of proteins that work together to maintain properly folded proteins. One of the overarching functions of the proteostasis network is the prevention or reversal of protein aggregation. How proteins aggregate in spite of the anti-aggregation activity of the proteostasis machinery is incompletely understood. Exposed hydrophobic patches can trigger degradation by the ubiquitin-proteasome system, a key branch of the proteostasis network. However, in a recent study, we found that model glycine (G)-rich or glutamine/asparagine (Q/N)-rich prion-like domains differ in their susceptibility to detection and degradation by this system. Here, we expand upon this work by examining whether the features controlling the degradation of our model prion-like domains generalize broadly to G-rich and Q/N-rich domains. Experimentally, native yeast G-rich domains in isolation are sensitive to the degradation-promoting effects of hydrophobic residues, whereas native Q/N-rich domains completely resist these effects and tend to aggregate instead. Bioinformatic analyses indicate that native G-rich domains from yeast and humans tend to avoid degradation-promoting features, suggesting that the proteostasis network may act as a form of selection at the molecular level that constrains the sequence space accessible to G-rich domains. However, the sensitivity or resistance of G-rich and Q/N-rich domains, respectively, was not always preserved in their native protein contexts, highlighting that proteins can evolve other sequence features to overcome the intrinsic sensitivity of some LCDs to degradation.

Mitochondrial Lon protease is a gatekeeper for proteins newly imported into the matrix

Human ATP-dependent Lon protease (LONP1) forms homohexameric, ring-shaped complexes. Depletion of LONP1 causes aggregation of a broad range of proteins in the mitochondrial matrix and decreases the levels of their soluble forms. The ATP hydrolysis activity, but not protease activity, of LONP1 is critical for its chaperone-like anti-aggregation activity. LONP1 forms a complex with the import machinery and an incoming protein, and protein aggregation is linked with matrix protein import. LONP1 also contributes to the degradation of imported, aberrant, unprocessed proteins using its protease activity. Taken together, our results show that LONP1 functions as a gatekeeper for specific proteins imported into the mitochondrial matrix.