Age-related and atherosclerosis-related erythropathy in ApoE/LDLR-/- mice

Human erythrocytes under stress. Spectroscopic fingerprints of known oxidative mechanisms and beyond

In this work, we investigated the oxidative stress-related biochemical alterations in red blood cells (RBCs) and their membranes with the use of spectroscopic techniques. We aimed to show their great advantage for the in situ detection of lipid classes and secondary structures of proteins without the need for their extraction in the cellular environment. The exposition of the cells to peroxides, t-butyl hydroperoxide (tBOOH) or hydrogen peroxide (H2O2) led to different degradation processes encompassing the changes in the composition of membranes and structural modifications of hemoglobin (Hb). Our results indicated that tBOOH is generally a stronger oxidizing agent than H2O2 and this observation was congruent with the activity of superoxide and glutathione peroxidase. ATR-FTIR and Raman spectroscopies of membranes revealed that tBOOH caused primarily the partial loss and peroxidation of the lipids resulting in loss of the integrity of membranes. In turn, both peroxides induced several kinds of damage in the protein layer, including the partial decrease of their content and irreversible aggregation of spectrin, ankyrin, and membrane-bound globin. These changes were especially pronounced on the membrane surface where stress conditions induced the formation of β-sheets and intramolecular aggregates, particularly for tBOOH. Interestingly, nano-FTIR spectroscopy revealed the lipid peroxidative damage on the membrane surface in both cases. As far as hemoglobin was concerned, tBOOH and H2O2 caused the increase of the oxyhemoglobin species and conformational alterations of its polypeptide chain into β-sheets. Our findings confirm that applied spectroscopies effectively track the oxidative changes occurring in the structural components of red blood cells and the simplicity of conducting measurements and sample preparation can be readily applied to pharmacological and clinical studies.

Surface-enhanced Raman scattering (SERS) and tip-enhanced Raman scattering (TERS) in label-free characterization of erythrocyte membranes and extracellular vesicles at the nano-scale and molecular level

The manuscript presents the potential of surface-enhanced Raman spectroscopy (SERS) and tip-enhanced Raman spectroscopy (TERS) for label-free characterization of extracellular microvesicles (EVs) and their isolated membranes derived from red blood cells (RBCs) at the nanoscale and at the single-molecule level, providing detection of a few individual amino acids, protein and lipid membrane compartments. The study shows future directions for research, such as investigating the use of the mentioned techniques for the detection and diagnosis of diseases. We demonstrate that SERS and TERS are powerful techniques for identifying the biochemical composition of EVs and their membranes, allowing the detection of small molecules, lipids, and proteins. Furthermore, extracellular vesicles released from red blood cells (REVs) can be broadly classified into exosomes, microvesicles, and apoptotic bodies, based on their size and biogenesis pathways. Our study specifically focuses on microvesicles that range from 100 to 1000 nanometres in diameter, as presented in AFM images. Using SERS and TERS spectra obtained for REVs and their membranes, we were able to characterize the chemical and structural properties of microvesicle membranes with high sensitivity and specificity. This information may help better distinguish and categorize different types of EVs, leading to a better understanding of their functions and potential biomedical applications.

Physicochemical understanding of biomineralization by molecular vibrational spectroscopy: From mechanism to nature

The process and mechanism of biomineralization and relevant physicochemical properties of mineral crystals are remarkably sophisticated multidisciplinary fields that include biology, chemistry, physics, and materials science. The components of the organic matter, structural construction of minerals, and related mechanical interaction, etc., could help to reveal the unique nature of the special mineralization process. Herein, the paper provides an overview of the biomineralization process from the perspective of molecular vibrational spectroscopy, including the physicochemical properties of biomineralized tissues, from physiological to applied mineralization. These physicochemical characteristics closely to the hierarchical mineralization process include biological crystal defects, chemical bonding, atomic doping, structural changes, and content changes in organic matter, along with the interface between biocrystals and organic matter as well as the specific mechanical effects for hardness and toughness. Based on those observations, the special physiological properties of mineralization for enamel and bone, as well as the possible mechanism of pathological mineralization and calcification such as atherosclerosis, tumor micro mineralization, and urolithiasis are also reviewed and discussed. Indeed, the clearly defined physicochemical properties of mineral crystals could pave the way for studies on the mechanisms and applications.

Secondary structure alterations of RBC assessed by FTIR-ATR in correlation to 2,3-DPG levels in ApoE/LDLR-/- Mice

In the present study, we characterized the secondary structure alterations of intact red blood cells (RBCs) cytosol with special attention to the sex-related alterations in 8- and 24-week-old female and male ApoE/LDLR^-/- mice, compared to age-matched female and male C57BL/6J control animals. Results were obtained with previously established methodology based on Fourier transform infrared spectroscopy-attenuated total reflectance (FTIR-ATR). Additionally, we evaluated 2,3-DPG levels in the RBCs and showed its potential link to the hemoglobin (Hb) secondary structure alterations. Considering Hb structure alterations probed by FTIR-ATR, the ratio of turns to α-helices in 8-week-old ApoE/LDLR^-/- mice suggested more pronounced secondary structure alterations within the RBCs than in the age-matched control. Sex-related differences were observed solely in 24-week-old male ApoE/LDLR^-/- mice, which showed statistically significant increase in the secondary structure alterations compared to 24-week-old female ApoE/LDLR^-/- mice. Similar to the secondary structure alterations, no sex-related differences were observed in the levels of 2,3-DPG in RBCs, except for 24-week-old male ApoE/LDLR^-/- mice, which showed significantly higher levels compared to the age-matched female ApoE/LDLR^-/- mice. Considering the age-related alterations, we observed significant increases in the intracellular 2,3-DPG of RBCs with animals' age in all studied groups, except for female ApoE/LDLR^-/- mice, where a significant difference was not reported. This suggests the clear correlation between secondary structure of Hb alterations and 2,3-DPG levels for male and female murine RBC and proves a higher resistance of older female RBCs to the secondary structure changes with progression of atherosclerosis. Moreover, it may be concluded that higher 2,3-DPG levels in RBCs occurred in response to the secondary structure alterations of Hb in ApoE/LDLR^-/- mice.

Association of Different Combinations of ALDH2 rs671, APOE rs429358, rs7412 Polymorphisms with Hypertension in Middle-Aged and Elderly People: A Case-Control Study

Background

Hypertensive patients have a younger trend, and studies on the role of genetic factors in hypertension susceptibility have been inconsistent. Aldehyde dehydrogenases 2 (ALDH2) and apolipoprotein E (APOE) are involved in the pathophysiological processes of hypertension. To investigate the relationship of ALDH2 and APOE polymorphisms with hypertension in middle-aged (30-59 years old) and elderly (≥60 years old) persons.

Methods

Two thousand six hundred and ten hypertensive patients and 1921 controls were included (between 30 and 100 years old). The genotypes of common polymorphisms in APOE and ALDH2 genes (APOE rs429358, rs7412, and ALDH2 rs671) of the subjects were analyzed by polymerase-chain reaction (PCR)-microarray. Statistical analyses (Student's t-test, Mann-Whitney U-test, χ ² test, and logistic regression analysis) were performed with SPSS v21.0.

Results

There were 4531 participants (66.60 ± 12.10 years old) in this study, including 3057 (67.5%) males and 1474 (32.5%) females. There were no significant differences in distributions of ALDH2 rs671, APOE rs429358/rs7412 genotypes and alleles between hypertensive patients and controls. Persons with ALDH2 rs671 G/A or A/A genotype were less likely to have hypertension (G/A+A/A vs G/G: gender-, age-, smoking-, and drinking-adjusted OR 0.885, 95% CI 0.785-0.997, P=0.045), while ALDH2 rs671 A/A+APOE rs429358 or rs7412 wild-type genotype may decrease the risk of hypertension. In middle-aged group, ALDH2 rs671 G/A+APOE rs429358 T/C carriers (adjusted OR 0.547, 95% CI 0.350-0.856, P=0.008), and ALDH2 rs671 A/A+APOE rs7412 C/C genotypes (adjusted OR 0.567, 95% CI 0.361-0.891, P=0.014) were less likely to have hypertension. In elderly group, APOE rs7412 T/T carriers were more likely to have hypertension (rs671 T/T vs C/C: adjusted OR 4.755, 95% CI 1.075-21.027, P=0.040; rs671 T/T vs C/C or C/T: adjusted OR 4.734, 95% CI 1.071-20.928, P=0.040).

Conclusion

Polymorphism-polymorphism interactions of ALDH2 rs671 and APOE rs429358/rs7412 may effect on hypertension susceptibility. Different genotypes comparison shows different roles in middle-aged and elderly people, respectively.

An Updated Review and Meta Analysis of Lipoprotein Glomerulopathy

More than 200 cases of lipoprotein glomerulopathy (LPG) have been reported since it was first discovered 30 years ago. Although relatively rare, LPG is clinically an important cause of nephrotic syndrome and end-stage renal disease. Mutations in the APOE gene are the leading cause of LPG. APOE mutations are an important determinant of lipid profiles and cardiovascular health in the population and can precipitate dysbetalipoproteinemia and glomerulopathy. Apolipoprotein E-related glomerular disorders include APOE2 homozygote glomerulopathy and LPG with heterozygous APOE mutations. In recent years, there has been a rapid increase in the number of LPG case reports and some progress in research into the mechanism and animal models of LPG. We consequently need to update recent epidemiological studies and the molecular mechanisms of LPG. This endeavor may help us not only to diagnose and treat LPG in a more personized manner but also to better understand the potential relationship between lipids and the kidney.

Sex-Specific Differences of Adenosine Triphosphate Levels in Red Blood Cells Isolated From ApoE/LDLR Double-Deficient Mice

In this study for the first time, we investigated the correlation between sex-specific differences in adenosine triphosphate (ATP) levels in red blood cells (RBCs) and their mechanical, biochemical, and morphological alterations during the progression of atherosclerosis in ApoE/LDLR double-deficient (ApoE/LDLR^−/−) mice. Our results indicate that both sex and age affect alterations in RBCs of both ApoE/LDLR^−/− and C57BL/6J mice. When compared with male RBCs, female RBCs were characterized by lower basal ATP and mean corpuscular hemoglobin concentration (MCHC), higher hemoglobin concentration (HGB), mean corpuscular volume (MCV), mean corpuscular hemoglobin (MCH), deformability, and phosphatidylserine (PS) exposure levels, regardless of age in both, ApoE/LDLR^−/− and C57BL/6J mice. ApoE/LDLR^−/− mice compared with age-matched controls showed lower basal ATP levels regardless of age and sex. Intracellular ATP level of RBCs was decreased solely in senescent female C57BL/6J mice, while it was elevated in males. Basal extracellular ATP levels were 400 times lower than corresponding intracellular level. In conclusion, basal ATP levels, RBC morphology, deformability, PS exposure levels alterations are sex-dependent in mice. Changes in basal ATP levels were correlated with PS exposure and trends of changes in MCV. Trends of changes of the most RBC parameters were similar in both sexes of ApoE/LDLR^−/− mice compared with age-matched controls; however, their kinetics and levels vary greatly between different stages of disease progression.

Short-term exposure to acrylamide exacerbated metabolic disorders and increased metabolic toxicity susceptibility on adult male mice with diabetes

Diabetes mellitus is a common endocrine metabolic disorder, and previous studies have shown that diabetics are more sensitive to the toxic environmental contaminants. Acrylamide (ACR) is both an industrially multipurpose compound and a common endogenous food contaminant to which people are frequently exposed and at high risk. However, the toxicity of ACR on diabetes hasn't attracted much attention. In this study, both healthy mice and diabetic mice received ACR administration orally to investigate the ACR-induced metabolic toxicity, mechanism and susceptibility to ACR toxicity in adult diabetic male mice. The results showed that ACR significantly increased FBG level and decreased bodyweight, serum lipid and liver lipid biomarkers (TC, TG, LDL-C, HDL-C) levels as well as expression of lipid and glucose metabolism-related genes in diabetic mice, indicating that ACR can exacerbate metabolic disorders of glucose and lipid in diabetic male mice. Moreover, ACR exposure significantly increased levels of MDA and COX-2), decreased GSH level and antioxidant enzyme activity (SOD, GSH-PX and CAT) by downregulating expression of Nrf2 and Keap1 in diabetic mice. Factorial analysis showed ACR had a more significant disturbance in diabetic mice compared with healthy mice. Our results indicated that ACR exposure can cause oxidative stress and inflammatory damage, which can exacerbate abnormal glucose and lipid metabolism. This work helps to elucidate the effects and underlying mechanisms of ACR-induced metabolic toxicity in adults with diabetes.

Epidemiological and genetic overlap among biological aging clocks: New challenges in biogerontology

Estimators of biological age (BA) - defined as the hypothetical underlying age of an organism - have attracted more and more attention in the last years, especially after the advent of new algorithms based on machine learning and genetic markers. While different aging clocks reportedly predict mortality in the general population, very little is known on their overlap. Here we review the evidence reported so far to support the existence of a partial overlap among different BA acceleration estimators, both from an epidemiological and a genetic perspective. On the epidemiological side, we review evidence supporting shared and independent influence on mortality risk of different aging clocks - including telomere length, brain, blood and epigenetic aging - and provide an overview of how an important exposure like diet may affect the different aging systems. On the genetic side, we apply linkage disequilibrium score regression analyses to support the existence of partly shared genomic overlap among these aging clocks. Through multivariate analysis of published genetic associations with these clocks, we also identified the most associated variants, genes, and pathways, which may affect common mechanisms underlying biological aging of different systems within the body. Based on our analyses, the most implicated pathways were involved in inflammation, lipid and carbohydrate metabolism, suggesting them as potential molecular targets for future anti-aging interventions. Overall, this review is meant as a contribution to the knowledge on the overlap of aging clocks, trying to clarify their shared biological basis and epidemiological implications.

Temporal relationship between systemic endothelial dysfunction and alterations in erythrocyte function in a murine model of chronic heart failure

Aims

Endothelial dysfunction (ED) and red blood cell distribution width (RDW) are both prognostic factors in heart failure (HF), but the relationship between them is not clear. In this study, we used a unique mouse model of chronic HF driven by cardiomyocyte-specific overexpression of activated Gαq protein (Tgαq*44 mice) to characterize the relationship between the development of peripheral ED and the occurrence of structural nanomechanical and biochemical changes in red blood cells (RBCs).

Methods and results

Systemic ED was detected in vivo in 8-month-old Tgαq*44 mice, as evidenced by impaired acetylcholine-induced vasodilation in the aorta and increased endothelial permeability in the brachiocephalic artery. ED in the aorta was associated with impaired nitric oxide (NO) production in the aorta and diminished systemic NO bioavailability. ED in the aorta was also characterized by increased superoxide and eicosanoid production. In 4- to 6-month-old Tgαq*44 mice, RBC size and membrane composition displayed alterations that did not result in significant changes in their nanomechanical and functional properties. However, 8-month-old Tgαq*44 mice presented greatly accentuated structural and size changes and increased RBC stiffness. In 12-month-old Tgαq*44 mice, the erythropathy was featured by severely altered RBC shape and elasticity, increased RDW, impaired RBC deformability, and increased oxidative stress (gluthatione (GSH)/glutathione disulfide (GSSG) ratio). Moreover, RBCs taken from 12-month-old Tgαq*44 mice, but not from 12-month-old FVB mice, coincubated with aortic rings from FVB mice, induced impaired endothelium-dependent vasodilation and this effect was partially reversed by an arginase inhibitor [2(S)-amino-6-boronohexanoic acid].

Conclusion

In the Tgαq*44 murine model of HF, systemic ED accelerates erythropathy and, conversely, erythropathy may contribute to ED. These results suggest that erythropathy may be regarded as a marker and a mediator of systemic ED in HF. RBC arginase and possibly other RBC-mediated mechanisms may represent novel therapeutic targets for systemic ED in HF.

Tauroursodeoxycholic Acid (TUDCA)-Lipid Interactions and Antioxidant Properties of TUDCA Studied in Model of Photoreceptor Membranes

Tauroursodeoxycholic acid (TUDCA), a hydrophilic bile acid containing taurine conjugated with the ursodeoxycholic acid (UDCA), has been known and used from ancient times as a therapeutic compound in traditional Chinese medicine. TUDCA has recently been gaining significant interest as a neuroprotective agent, also exploited in the visual disorders. Among several mechanisms of TUDCA's protective action, its antioxidant activity and stabilizing effect on mitochondrial and plasma membranes are considered. In this work we investigated antioxidant activity of TUDCA and its impact on structural properties of model membranes of different composition using electron paramagnetic resonance spectroscopy and the spin labeling technique. Localization of TUDCA molecules in a pure POPC bilayer has been studied using a molecular dynamics simulation (MD). The obtained results indicate that TUDCA is not an efficient singlet oxygen (1O2 (1Δg)) quencher, and the determined rate constant of its interaction with 1O2 (1Δg) is only 1.9 × 105 M-1s-1. However, in lipid oxidation process induced by a Fenton reaction, TUDCA reveals substantial antioxidant activity significantly decreasing the rate of oxygen consumption in the system studied. In addition, TUDCA induces slight, but noticeable changes in the polarity and fluidity of the investigated model membranes. The results of performed MD simulation correspond very well with the experimental results.

An Insight into the Stages of Ion Leakage during Red Blood Cell Storage

Packed red blood cells (pRBCs), the most commonly transfused blood product, are exposed to environmental disruptions during storage in blood banks. In this study, temporal sequence of changes in the ion exchange in pRBCs was analyzed. Standard techniques commonly used in electrolyte measurements were implemented. The relationship between ion exchange and red blood cells (RBCs) morphology was assessed with use of atomic force microscopy with reference to morphological parameters. Variations observed in the Na⁺, K⁺, Cl⁻, H⁺, HCO₃⁻, and lactate ions concentration show a complete picture of singly-charged ion changes in pRBCs during storage. Correlation between the rate of ion changes and blood group type, regarding the limitations of our research, suggested, that group 0 is the most sensitive to the time-dependent ionic changes. Additionally, the impact of irreversible changes in ion exchange on the RBCs membrane was observed in nanoscale. Results demonstrate that the level of ion leakage that leads to destructive alterations in biochemical and morphological properties of pRBCs depend on the storage timepoint.

Spectroscopic Signature of Red Blood Cells in a D-Galactose-Induced Accelerated Aging Model

This work presents a semi-quantitative spectroscopic approach, including FTIR-ATR and Raman spectroscopies, for the biochemical analysis of red blood cells (RBCs) supported by the biochemical, morphological and rheological reference techniques. This multi-modal approach provided the description of the RBC alterations at the molecular level in a model of accelerated aging induced by administration of D-galactose (D-gal), in comparison to natural aging. Such an approach allowed to conclude that most age-related biochemical RBC membrane changes (a decrease in lipid unsaturation and the level of phospholipids, or an increase in acyl chain shortening) as well as alterations in the morphological parameters and RBC deformability are well reflected in the D-gal model of accelerated aging. Similarly, as in natural aging, a decrease in LDL level in blood plasma and no changes in the fraction of glucose, creatinine, total cholesterol, HDL, iron, or triglycerides were observed during the course of accelerated aging. Contrary to natural aging, the D-gal model led to an increase in cholesterol esters and the fraction of total esterified lipids in RBC membranes, and evoked significant changes in the secondary structure of the membrane proteins. Moreover, a significant decrease in the phosphorous level of blood plasma was specific for the D-gal model. On the other hand, natural aging induced stronger changes in the secondary structures of the proteins of the RBCs' interior. This work proves that research on the aging mechanism, especially in circulation-related diseases, should employ the D-gal model with caution. Nonetheless, the D-gal model enables to imitate age-related rheological alterations in RBCs, although they are partially derived from different changes observed in the RBC membrane at the molecular level.