Myocardial lipofuscin accumulation in ageing and sudden cardiac death

Ultrastructural cardiac pathology: the wide (yet so very small) world of cardiac electron microscopy

Electron microscopy (EM) was a popular diagnostic tool in the 1970s and early 80s. With the adoption of newer, less expensive techniques, such as immunohistochemistry, the role of EM in diagnostic surgical pathology has dwindled substantially. Nowadays, even in academic centers, EM interpretation is relegated to renal pathologists and the handful of (aging) pathologists with experience using the technique. As such, EM interpretation is truly arcane-understood by few and mysterious to many. Nevertheless, there remain situations in which EM is the best or only ancillary test to ascertain a specific diagnosis. Thus, there remains a critical need for the younger generation of surgical pathologists to learn EM interpretation. Recognizing this need, cardiac EM was made the theme of the Cardiovascular Evening Specialty Conference at the 2023 United States and Canadian Academy of Pathology (USCAP) annual meeting in New Orleans, Louisiana. Each of the speakers contributed their part to this article, the purpose of which is to review EM as it pertains to myocardial tissue and provide illustrative examples of the spectrum of ultrastructural cardiac pathology seen in storage/metabolic diseases, cardiomyopathies, infiltrative disorders, and cardiotoxicities.

The age pigment lipofuscin causes oxidative stress, lysosomal dysfunction, and pyroptotic cell death

Accumulation of the age pigment lipofuscin represents a ubiquitous hallmark of the aging process. However, our knowledge about cellular effects of lipofuscin accumulation is potentially flawed, because previous research mainly utilized highly artificial methods of lipofuscin generation. In order to address this tremendous problem, we developed a convenient protocol for isolation of authentic lipofuscin from human and equine cardiac tissue in high purity and quantity. Isolated lipofuscin aggregates contained elevated concentrations of proline and metals such as calcium or iron. The material was readily incorporated by fibroblasts and caused cell death at low concentrations (LC50 = 5.0 μg/mL) via a pyroptosis-like pathway. Lipofuscin boosted mitochondrial ROS production and caused lysosomal dysfunction by lysosomal membrane permeabilization leading to reduced lysosome quantity and impaired cathepsin D activity. In conclusion, this is the first study utilizing authentic lipofuscin to experimentally validate the concept of the lysosomal-mitochondrial axis theory of aging and cell death.

HIV Protein Nef Induces Cardiomyopathy Through Induction of Bcl2 and p21

HIV-associated cardiovascular diseases remain a leading cause of death in people living with HIV/AIDS (PLWHA). Although antiretroviral drugs suppress the viral load, they fail to remove the virus entirely. HIV-1 Nef protein is known to play a role in viral virulence and HIV latency. Expression of Nef protein can be detected in different organs, including cardiac tissue. Despite the established role of Nef protein in HIV-1 replication, its impact on organ function inside the human body is not clear. To understand the effect of Nef at the organ level, we created a new Nef-transgenic (Nef-TG) mouse that expresses Nef protein in the heart. Our study found that Nef expression caused inhibition of cardiac function and pathological changes in the heart with increased fibrosis, leading to heart failure and early mortality. Further, we found that cellular autophagy is significantly inhibited in the cardiac tissue of Nef-TG mice. Mechanistically, we found that Nef protein causes the accumulation of Bcl2 and Beclin-1 proteins in the tissue, which may affect the cellular autophagy system. Additionally, we found Nef expression causes upregulation of the cellular senescence marker p21 and senescence-associated β-galactosidase expression. Our findings suggest that the Nef-mediated inhibition of autophagy and induction of senescence markers may promote aging in PLWHA. Our mouse model could help us to understand the effect of Nef protein on organ function during latent HIV infection.

Cardiac T1ρ Mapping Values Affected by Age and Sex in a Healthy Chinese Cohort

BACKGROUND

To facilitate the clinical use of cardiac T1ρ, it is important to understand the impact of age and sex on T1ρ values of the myocardium.

PURPOSE

To investigate the impact of age and gender on myocardial T1ρ values.

STUDY TYPE

Cross-sectional.

POPULATION

Two hundred ten healthy Han Chinese volunteers without cardiovascular risk factors (85 males, mean age 34.4 ± 12.5 years; 125 females, mean age 37.9 ± 14.8 years).

FIELD STRENGTH/SEQUENCE

1.5 T; T1ρ-prepared steady-state free precession (T1ρ mapping) sequence.

ASSESSMENT

Basal, mid, and apical short-axis left ventricular T1ρ maps were acquired. T1ρ maps acquired with spin-lock frequencies of 5 and 400 Hz were subtracted to create a myocardial fibrosis index (mFI) map. T1ρ and mFI values across different age decades, sex, and slice locations were compared.

STATISTICAL TESTS

Shapiro-Wilk test, Student's t test, Mann-Whitney U test, linear regression analysis, one-way analysis of variance and intraclass correlation coefficient.

SIGNIFICANCE

P value <0.05.

RESULTS

Women had significantly higher T1ρ and mFI values than men (50.3 ± 2.0 msec vs. 47.7 ± 2.4 msec and 4.7 ± 1.0 msec vs. 4.3 ± 1.1 msec, respectively). Additionally, in males and females combined, there was a significant positive but weak correlation between T1ρ values and age (r = 0.27), while no correlation was observed between the mFI values and age (P = 0.969).

DATA CONCLUSION

We report potential reference values for cardiac T1ρ by sex, age distribution, and slice location in a Chinese population. T1ρ was significantly correlated with age and sex, while mFI was only associated with sex.

EVIDENCE LEVEL

2 TECHNICAL EFFICACY: Stage 1.

Research progress on interferon and cellular senescence

Since the 12 major signs of aging were revealed in 2023, people's interpretation of aging will go further, which is of great significance for understanding the occurrence, development, and intervention in the aging process. As one of the 12 major signs of aging, cellular senescence refers to the process in which the proliferation and differentiation ability of cells decrease under stress stimulation or over time, often manifested as changes in cell morphology, cell cycle arrest, and decreased metabolic function. Interferon (IFN), as a secreted ligand for specific cell surface receptors, can trigger the transcription of interferon-stimulated genes (ISGs) and play an important role in cellular senescence. In addition, IFN serves as an important component of SASP, and the activation of the IFN signaling pathway has been shown to contribute to cell apoptosis and senescence. It is expected to delay cellular senescence by linking IFN with cellular senescence and studying the effects of IFN on cellular senescence and its mechanism. This article provides a review of the research on the relationship between IFN and cellular senescence by consulting relevant literature.

Ceruloplasmin and Lipofuscin Serum Concentrations Are Associated with Presence of Hypertrophic Cardiomyopathy

Oxidative stress reflects an imbalance between the systemic manifestation of reactive oxygen species and cells' ability to neutralize them by antioxidant systems. The role of oxidative stress in hypertrophic cardiomyopathy (HCM) is not fully understood. The aim of the study was to examine selected parameters of oxidative stress in patients with HCM compared to the control group. We enrolled 85 consecutive HCM patients and 97 controls without HCM. The groups were matched for sex, the body mass index, and age. Oxidative stress markers included superoxide dismutase (SOD), ceruloplasmin (CER), and lipofuscin (LPS). The median age of the HCM patients was 53 (40-63) years, and 41.2% of them were male. HCM patients, compared to the control ones, had significantly increased levels of CER and LPS. The areas under the receiver operating characteristics curves (AUC) indicated a good discriminatory power of CER (AUC 0.924, sensitivity 84%, and specificity 88%), an acceptable discriminatory power of LPS (AUC 0.740, sensitivity 66%, and specificity 72%), and poor discriminatory power of SOD (AUC 0.556, sensitivity 34%, and specificity 94%) for HCM detection. CER with good predictive strength, as well as LPS with acceptable predictive power, allows for HCM detection. The utility of SOD for HCM detection is limited.

Molecular Signatures of Senescence in Periodontitis: Clinical Insights

Most of the elderly population is afflicted by periodontal diseases, creating a health burden worldwide. Cellular senescence is one of the hallmarks of aging and associated with several chronic comorbidities. Senescent cells produce a variety of deleterious secretions, collectively termed the senescence-associated secretory phenotype (SASP). This disrupts neighboring cells, leading to further senescence propagation and inciting chronic inflammation, known as "inflammaging." Detrimental repercussions within the tissue microenvironment can trigger senescence at a younger age, accelerate biological aging, and drive the initiation or progression of diseases. Here, we investigated the biological signatures of senescence in healthy and diseased gingival tissues by assessing the levels of key senescence markers (p16, lipofuscin, and β-galactosidase) and inflammatory mediators (interleukin [IL]-1β, IL-6, IL-8, matrix metalloproteinase [MMP]-1, MMP-3, and tumor necrosis factor-α). Our results showed significantly increased senescence features including p16, lipofuscin, and β-galactosidase in both epithelial and connective tissues of periodontitis patients compared with healthy sites in all age groups, indicating that an inflammatory microenvironment can trigger senescence-like alterations in younger diseased gingival tissues as well. Subsequent analyses using double staining with specific cell markers noted the enrichment of β-galactosidase in fibroblasts and macrophages. Concurrently, inflammatory mediators consistent with SASP were increased in the gingival biopsies obtained from periodontitis lesions. Together, our findings provide the first clinical report revealing susceptibility to elevated senescence and inflammatory milieu consistent with senescence secretome in gingival tissues, thus introducing senescence as one of the drivers of pathological events in the oral mucosa and a novel strategy for targeted interventions.

Revisiting Cardiac Biology in the Era of Single Cell and Spatial Omics

Throughout our lifetime, each beat of the heart requires the coordinated action of multiple cardiac cell types. Understanding cardiac cell biology, its intricate microenvironments, and the mechanisms that govern their function in health and disease are crucial to designing novel therapeutical and behavioral interventions. Recent advances in single-cell and spatial omics technologies have significantly propelled this understanding, offering novel insights into the cellular diversity and function and the complex interactions of cardiac tissue. This review provides a comprehensive overview of the cellular landscape of the heart, bridging the gap between suspension-based and emerging in situ approaches, focusing on the experimental and computational challenges, comparative analyses of mouse and human cardiac systems, and the rising contextualization of cardiac cells within their niches. As we explore the heart at this unprecedented resolution, integrating insights from both mouse and human studies will pave the way for novel diagnostic tools and therapeutic interventions, ultimately improving outcomes for patients with cardiovascular diseases.

The ameliorative mechanism of Lactiplantibacillus plantarum NJAU-01 against D-galactose induced oxidative stress: a hepatic proteomics and gut microbiota analysis

Probiotic intervention is an effective strategy to alleviate oxidative stress-related diseases. Our previous studies found that Lactiplantibacillus plantarum NJAU-01 (NJAU-01) exhibited antioxidant effects in a D-galactose (D-gal)-induced aging mouse model. However, the underlying mechanism remains to be unveiled. This study was aimed to investigate the ameliorative effect and mechanism of NJAU-01 against oxidative stress induced by D-gal. The results showed that NJAU-01 could reverse the tendency of a slow body weight gain induced by D-gal. NJAU-01 relieved hepatic oxidative stress via increasing the hepatic total antioxidant capacity and antioxidant enzyme activities including superoxide dismutase (SOD), glutathione peroxidase (GSH-Px) and catalase (CAT). Moreover, the malondialdehyde (MDA) level was reversed after NJAU-01 supplementation. The proteomic results showed that there were 201 differentially expressed proteins (DEPs) between NJAU-01 and D-gal groups. NJAU-01 regulated the expressions of glutathione S-transferase Mu 5 (Gstm5), glutathione S-transferase P2 (Gstp2) and NADH dehydrogenase 1α subcomplex subunit 7 (Ndufa7) related to oxidative stress, and autophagy protein 5 (Atg5) and plasma alpha-L-fucosidase (Fuca2) involved in autophagy, etc. 16S rDNA sequencing results showed that NJAU-01 supplementation could regulate the gut microbiota dysbiosis induced by D-gal via increasing the relative abundances of the phylum Firmicutes and the genus Lactobacillus and reducing the relative abundances of the phylum Bacteroidetes and the genera Lachnospiraceae_NK4A136_group as well as Prevotellaceae_UCG-001, etc.. Spearman correlation analysis results showed that the altered gut microbiota composition had a significant correlation with antioxidant enzyme activities and the DEPs related to oxidative stress. Overall, NJAU-01 alleviated hepatic oxidative stress induced by D-gal via manipulating the gut microbiota composition and hepatic protein expression profile.

Fibrosis and expression of extracellular matrix proteins in human interventricular septum in aortic valve stenosis and regurgitation

Valvular heart disease leads to ventricular pressure and/or volume overload. Pressure overload leads to fibrosis, which might regress with its resolution, but the limits and details of this reverse remodeling are not known. To gain more insight into the extent and nature of cardiac fibrosis in valve disease, we analyzed needle biopsies taken from the interventricular septum of patients undergoing surgery for valve replacement focusing on the expression and distribution of major extracellular matrix protein involved in this process. Proteomic analysis performed using mass spectrometry revealed an excellent correlation between the expression of collagen type I and III, but there was little correlation with the immunohistochemical staining performed on sister sections, which included antibodies against collagen I, III, fibronectin, sarcomeric actin, and histochemistry for wheat germ agglutinin. Surprisingly, the immunofluorescence intensity did not correlate significantly with the gold standard for fibrosis quantification, which was performed using Picrosirius Red (PSR) staining, unless multiplexed on the same tissue section. There was also little correlation between the immunohistochemical markers and pressure gradient severity. It appears that at least in humans, the immunohistochemical pattern of fibrosis is not clearly correlated with standard Picrosirius Red staining on sister sections or quantitative proteomic data, possibly due to tissue heterogeneity at microscale, comorbidities, or other patient-specific factors. For precise correlation of different types of staining, multiplexing on the same section is the best approach.

Improved immunostaining of nanostructures and cells in human brain specimens through expansion-mediated protein decrowding

Proteins are densely packed in cells and tissues, where they form complex nanostructures. Expansion microscopy (ExM) variants have been used to separate proteins from each other in preserved biospecimens, improving antibody access to epitopes. Here, we present an ExM variant, decrowding expansion pathology (dExPath), that can expand proteins away from each other in human brain pathology specimens, including formalin-fixed paraffin-embedded (FFPE) clinical specimens. Immunostaining of dExPath-expanded specimens reveals, with nanoscale precision, previously unobserved cellular structures, as well as more continuous patterns of staining. This enhanced molecular staining results in observation of previously invisible disease marker-positive cell populations in human glioma specimens, with potential implications for tumor aggressiveness. dExPath results in improved fluorescence signals even as it eliminates lipofuscin-associated autofluorescence. Thus, this form of expansion-mediated protein decrowding may, through improved epitope access for antibodies, render immunohistochemistry more powerful in clinical science and, perhaps, diagnosis.

A review of the pathophysiological mechanisms of doxorubicin-induced cardiotoxicity and aging

The population of cancer survivors is rapidly increasing due to improving healthcare. However, cancer therapies often have long-term side effects. One example is cancer therapy-related cardiac dysfunction (CTRCD) caused by doxorubicin: up to 9% of the cancer patients treated with this drug develop heart failure at a later stage. In recent years, doxorubicin-induced cardiotoxicity has been associated with an accelerated aging phenotype and cellular senescence in the heart. In this review we explain the evidence of an accelerated aging phenotype in the doxorubicin-treated heart by comparing it to healthy aged hearts, and shed light on treatment strategies that are proposed in pre-clinical settings. We will discuss the accelerated aging phenotype and the impact it could have in the clinic and future research.

Lipofuscin, Its Origin, Properties, and Contribution to Retinal Fluorescence as a Potential Biomarker of Oxidative Damage to the Retina

Lipofuscin accumulates with age as intracellular fluorescent granules originating from incomplete lysosomal digestion of phagocytosed and autophagocytosed material. The purpose of this review is to provide an update on the current understanding of the role of oxidative stress and/or lysosomal dysfunction in lipofuscin accumulation and its consequences, particularly for retinal pigment epithelium (RPE). Next, the fluorescence of lipofuscin, spectral changes induced by oxidation, and its contribution to retinal fluorescence are discussed. This is followed by reviewing recent developments in fluorescence imaging of the retina and the current evidence on the prognostic value of retinal fluorescence for the progression of age-related macular degeneration (AMD), the major blinding disease affecting elderly people in developed countries. The evidence of lipofuscin oxidation in vivo and the evidence of increased oxidative damage in AMD retina ex vivo lead to the conclusion that imaging of spectral characteristics of lipofuscin fluorescence may serve as a useful biomarker of oxidative damage, which can be helpful in assessing the efficacy of potential antioxidant therapies in retinal degenerations associated with accumulation of lipofuscin and increased oxidative stress. Finally, amendments to currently used fluorescence imaging instruments are suggested to be more sensitive and specific for imaging spectral characteristics of lipofuscin fluorescence.

Interindividual Age-Independent Differences in Human CX43 Impact Ventricular Arrhythmic Risk

Connexin 43 (CX43) is one of the major components of gap junctions, the structures responsible for the intercellular communication and transmission of the electrical impulse in the left ventricle. There is limited information on the histological changes of CX43 with age and their effect on electrophysiology, especially in humans. Here, we analyzed left ventricular biopsies from living donors starting at midlife to characterize age-related CX43 remodeling. We assessed its quantity, degree of lateralization, and spatial heterogeneity together with fibrotic deposition. We observed no significant age-related remodeling of CX43. Only spatial heterogeneity increased slightly with age, and this increase was better explained by biological age than by chronological age. Importantly, we found that CX43 features varied considerably among individuals in our population with no relevant relationship to age or fibrosis content, in contrast to animal species. We used our experimental results to feed computational models of human ventricular electrophysiology and to assess the effects of interindividual differences in specific features of CX43 and fibrosis on conduction velocity, action potential duration, and arrhythmogenicity. We found that larger amounts of fibrosis were associated with the highest arrhythmic risk, with this risk being increased when fibrosis deposition was combined with a reduction in CX43 amount and/or with an increase in CX43 spatial heterogeneity. These mechanisms underlying high arrhythmic risk in some individuals were not associated with age in our study population. In conclusion, our data rule out CX43 remodeling as an age-related arrhythmic substrate in the population beyond midlife, but highlight its potential as a proarrhythmic factor at the individual level, especially when combined with increased fibrosis.

The possible transport and exclusion mode of lipofuscin in rat myocardium under electron microscopy

Lipofuscin accumulation has been observed in human coronary arteries but whether or not myocardial tissue can release lipofuscin generated within cardiomyocytes must be clarified, as this may provide indicators for future anti-ageing research. The hearts of Sprague Dawley rats, aged 6-24 months, were embedded in resin and ultrathin sections cut for electron microscopy. Lipofuscin granules were abundant in cardiomyocytes. Cardiomyocytes were seen to release lipofuscin granules into the myocardial interstitium as cytoplasmic fragments with irregular protrusions on the sarcolemma surface. The cytoplasmic fragments entering the stroma fused directly with the endothelial cells of adjacent capillaries, delivering lipofuscin to the vessel wall. These fragments were also seen to be engulfed by stromal macrophages or fused with fibroblasts, which then combined with capillary endothelial cells to deliver lipofuscin to the vessel wall. Some cytoplasmic fragments disaggregated and formed membrane-like waste, which travelled to the vessel wall from the myocardial stroma as soluble fine particles via diffusion or pinocytosis of capillary endothelial cells. Lipofuscin entered the vascular wall and endothelial cells, forming large and small protrusions or folds that transported the lipofuscin to the vascular lumen and bloodstream.

Transcriptomic Profiling Identifies Ferroptosis-Related Gene Signatures in Ischemic Muscle Satellite Cells Affected by Peripheral Artery Disease-Brief Report

BACKGROUND

We hypothesized that transcriptomic profiling of muscle satellite cells in peripheral artery disease (PAD) would identify damage-related pathways contributing to skeletal muscle myopathy. We identified a potential role for ferroptosis-a form of programmed lytic cell death by iron-mediated lipid peroxidation-as one such pathway. Ferroptosis promotes myopathy in ischemic cardiac muscle but has an unknown role in PAD.

METHODS

Muscle satellite cells from donors with PAD were obtained during surgery. cDNA libraries were processed for single-cell RNA sequencing using the 10X Genomics platform. Protein expression was confirmed based on pathways inferred by transcriptomic analysis.

RESULTS

Unsupervised cluster analysis of over 25 000 cells aggregated from 8 donor samples yielded distinct cell populations grouped by a shared unique transcriptional fingerprint. Quiescent cells were diminished in ischemic muscle while myofibroblasts and apoptotic cells were prominent. Differential gene expression demonstrated a surprising increase in genes associated with iron transport and oxidative stress and a decrease in GPX4 (glutathione peroxidase 4) in ischemic PAD-derived cells. Release of the danger signal HMGB1 (high mobility group box-1) correlated with ferroptotic markers including surface transferrin receptor and were higher in ischemia. Furthermore, lipid peroxidation in muscle satellite cells was modulated by ferrostatin, a ferroptosis inhibitor. Histology confirmed iron deposition and lipofuscin, an inducer of ferroptosis in PAD-affected muscle.

CONCLUSIONS

This report presents a novel finding that genes known to be involved in ferroptosis are differentially expressed in human skeletal muscle affected by PAD. Targeting ferroptosis may be a novel therapeutic strategy to reduce PAD myopathy.

Neuronal Senescence in the Aged Brain

Cellular senescence is a highly complicated cellular state that occurs throughout the lifespan of an organism. It has been well-defined in mitotic cells by various senescent features. Neurons are long-lived post-mitotic cells with special structures and functions. With age, neurons display morphological and functional changes, accompanying alterations in proteostasis, redox balance, and Ca2+ dynamics; however, it is ambiguous whether these neuronal changes belong to the features of neuronal senescence. In this review, we strive to identify and classify changes that are relatively specific to neurons in the aging brain and define them as features of neuronal senescence through comparisons with common senescent features. We also associate them with the functional decline of multiple cellular homeostasis systems, proposing the possibility that these systems are the main drivers of neuronal senescence. We hope this summary will serve as a steppingstone for further inputs on a comprehensive but relatively specific list of phenotypes for neuronal senescence and in particular their underlying molecular events during aging. This will in turn shine light on the association between neuronal senescence and neurodegeneration and lead to the development of strategies to perturb the processes.

Giant mitochondria in cardiomyocytes: cellular architecture in health and disease

Giant mitochondria are frequently observed in different disease models within the brain, kidney, and liver. In cardiac muscle, these enlarged organelles are present across diverse physiological and pathophysiological conditions including in ageing and exercise, and clinically in alcohol-induced heart disease and various cardiomyopathies. This mitochondrial aberration is widely considered an early structural hallmark of disease leading to adverse organ function. In this thematic paper, we discuss the current state-of-knowledge on the presence, structure and functional implications of giant mitochondria in heart muscle. Despite its demonstrated reoccurrence in different heart diseases, the literature on this pathophysiological phenomenon remains relatively sparse since its initial observations in the early 60s. We review historical and contemporary investigations from cultured cardiomyocytes to human tissue samples to address the role of giant mitochondria in cardiac health and disease. Finally, we discuss their significance for the future development of novel mitochondria-targeted therapies to improve cardiac metabolism and functionality.

Antioxidants Prevent Iron Accumulation and Lipid Peroxidation, but Do Not Correct Autophagy Dysfunction or Mitochondrial Bioenergetics in Cellular Models of BPAN

Neurodegeneration with brain iron accumulation (NBIA) is a group of rare neurogenetic disorders frequently associated with iron accumulation in the basal nuclei of the brain. Among NBIA subtypes, β-propeller protein-associated neurodegeneration (BPAN) is associated with mutations in the autophagy gene WDR45. The aim of this study was to demonstrate the autophagic defects and secondary pathological consequences in cellular models derived from two patients harboring WDR45 mutations. Both protein and mRNA expression levels of WDR45 were decreased in patient-derived fibroblasts. In addition, the increase of LC3B upon treatments with autophagy inducers or inhibitors was lower in mutant cells compared to control cells, suggesting decreased autophagosome formation and impaired autophagic flux. A transmission electron microscopy (TEM) analysis showed mitochondrial vacuolization associated with the accumulation of lipofuscin-like aggregates containing undegraded material. Autophagy dysregulation was also associated with iron accumulation and lipid peroxidation. In addition, mutant fibroblasts showed altered mitochondrial bioenergetics. Antioxidants such as pantothenate, vitamin E and α-lipoic prevented lipid peroxidation and iron accumulation. However, antioxidants were not able to correct the expression levels of WDR45, neither the autophagy defect nor cell bioenergetics. Our study demonstrated that WDR45 mutations in BPAN cellular models impaired autophagy, iron metabolism and cell bioenergetics. Antioxidants partially improved cell physiopathology; however, autophagy and cell bioenergetics remained affected.

Development of a method for evaluating skin dullness: A mathematical model explaining dullness by the color, optical properties, and microtopography of the skin

BACKGROUND

Skin dullness has long been a major concern of Japanese women. It is usually evaluated and judged visually by experts. Although several factors are recognized to play a role, it is unclear to what extent such physiological characteristics contribute to skin dullness. The purpose of this study is to establish an objective method for evaluation, which will assist in developing cosmetics products targeting skin dullness.

METHODS

We conducted a skin measurement study on 50 Japanese women in their 30-50s, where skin dullness was visually assessed by a group of experts to obtain an average dullness score, and several skin parameters were obtained. We then developed a regression model that explains the visual assessment score using these physiological parameters.

RESULTS

The results of partial least squares analysis of the dullness perception and physiological characteristics showed that skin dullness can be defined by colorimetric, optical, and skin surface microtopography parameters. Additionally, the contribution of each parameter to the model was determined. Our results suggest that dullness perception is highly affected by the melanin content and yellowness of the skin, followed by skin reddishness, roughness, and translucency score, whereas glossiness has less effect. Strikingly, the contribution ratio of each parameter varied among age groups. Furthermore, we confirmed that the predicted value of skin dullness increases with age.

CONCLUSION

Our results will help the design of cosmetics targeting factors specific to age groups in developing effective solutions for skin dullness.

Mitochondrial homeostasis: a potential target for delaying renal aging

Mitochondria, which are the energy factories of the cell, participate in many life activities, and the kidney is a high metabolic organ that contains abundant mitochondria. Renal aging is a degenerative process associated with the accumulation of harmful processes. Increasing attention has been given to the role of abnormal mitochondrial homeostasis in renal aging. However, the role of mitochondrial homeostasis in renal aging has not been reviewed in detail. Here, we summarize the current biochemical markers associated with aging and review the changes in renal structure and function during aging. Moreover, we also review in detail the role of mitochondrial homeostasis abnormalities, including mitochondrial function, mitophagy and mitochondria-mediated oxidative stress and inflammation, in renal aging. Finally, we describe some of the current antiaging compounds that target mitochondria and note that maintaining mitochondrial homeostasis is a potential strategy against renal aging.

Fluorescence intensity and lifetime imaging of lipofuscin-like autofluorescence for label-free predicting clinical drug response in cancer

Conventional techniques for in vitro cancer drug screening require labor-intensive formalin fixation, paraffin embedding, and dye staining of tumor tissues at fixed endpoints. This way of assessment discards the valuable pharmacodynamic information in live cells over time. Here, we found endogenous lipofuscin-like autofluorescence acutely accumulated in the cell death process. Its unique red autofluorescence could report the apoptosis without labeling and continuously monitor the treatment responses in 3D tumor-culture models. Lifetime imaging of lipofuscin-like red autofluorescence could further distinguish necrosis from apoptosis of cells. Moreover, this endogenous fluorescent marker could visualize the apoptosis in live zebrafish embryos during development. Overall, this study validates that lipofuscin-like autofluorophore is a generic cell death marker. Its characteristic autofluorescence could label-free predict the efficacy of anti-cancer drugs in organoids or animal models.

Direct proteomic and high-resolution microscopy biopsy analysis identifies distinct ventricular fates in severe aortic stenosis

The incidence of aortic valve stenosis (AS), the most common reason for aortic valve replacement (AVR), increases with population ageing. While untreated AS is associated with high mortality, different hemodynamic subtypes range from normal left-ventricular function to severe heart failure. However, the molecular nature underlying four different AS subclasses, suggesting vastly different myocardial fates, is unknown. Here, we used direct proteomic analysis of small left-ventricular biopsies to identify unique protein expression profiles and subtype-specific AS mechanisms. Left-ventricular endomyocardial biopsies were harvested from patients during transcatheter AVR, and inclusion criteria were based on echocardiographic diagnosis of severe AS and guideline-defined AS-subtype classification: 1) normal ejection fraction (EF)/high-gradient; 2) low EF/high-gradient; 3) low EF/low-gradient; and 4) paradoxical low-flow/low-gradient AS. Samples from non-failing donor hearts served as control. We analyzed 25 individual left-ventricular biopsies by data-independent acquisition mass spectrometry (DIA-MS), and 26 biopsies by histomorphology and cardiomyocytes by STimulated Emission Depletion (STED) superresolution microscopy. Notably, DIA-MS reliably detected 2273 proteins throughout each individual left-ventricular biopsy, of which 160 proteins showed significant abundance changes between AS-subtype and non-failing samples including the cardiac ryanodine receptor (RyR2). Hierarchical clustering segregated unique proteotypes that identified three hemodynamic AS-subtypes. Additionally, distinct proteotypes were linked with AS-subtype specific differences in cardiomyocyte hypertrophy. Furthermore, superresolution microscopy of immunolabeled biopsy sections showed subcellular RyR2-cluster fragmentation and disruption of the functionally important association with transverse tubules, which occurred specifically in patients with systolic dysfunction and may hence contribute to depressed left-ventricular function in AS.

Targeting Immune Senescence in Atherosclerosis

Atherosclerosis is one of the main underlying causes of cardiovascular diseases (CVD). It is associated with chronic inflammation and intimal thickening as well as the involvement of multiple cell types including immune cells. The engagement of innate or adaptive immune response has either athero-protective or atherogenic properties in exacerbating or alleviating atherosclerosis. In atherosclerosis, the mechanism of action of immune cells, particularly monocytes, macrophages, dendritic cells, and B- and T-lymphocytes have been discussed. Immuno-senescence is associated with aging, viral infections, genetic predispositions, and hyperlipidemia, which contribute to atherosclerosis. Immune senescent cells secrete SASP that delays or accelerates atherosclerosis plaque growth and associated pathologies such as aneurysms and coronary artery disease. Senescent cells undergo cell cycle arrest, morphological changes, and phenotypic changes in terms of their abundances and secretome profile including cytokines, chemokines, matrix metalloproteases (MMPs) and Toll-like receptors (TLRs) expressions. The senescence markers are used in therapeutics and currently, senolytics represent one of the emerging treatments where specific targets and clearance of senescent cells are being considered as therapy targets for the prevention or treatment of atherosclerosis.

Vicious cycle of lipid peroxidation and iron accumulation in neurodegeneration

Lipid peroxidation and iron accumulation are closely associated with neurodegenerative diseases, such as Alzheimer's, Parkinson's, and Huntington's diseases, or neurodegeneration with brain iron accumulation disorders. Mitochondrial dysfunction, lipofuscin accumulation, autophagy disruption, and ferroptosis have been implicated as the critical pathomechanisms of lipid peroxidation and iron accumulation in these disorders. Currently, the connection between lipid peroxidation and iron accumulation and the initial cause or consequence in neurodegeneration processes is unclear. In this review, we have compiled the known mechanisms by which lipid peroxidation triggers iron accumulation and lipofuscin formation, and the effect of iron overload on lipid peroxidation and cellular function. The vicious cycle established between both pathological alterations may lead to the development of neurodegeneration. Therefore, the investigation of these mechanisms is essential for exploring therapeutic strategies to restrict neurodegeneration. In addition, we discuss the interplay between lipid peroxidation and iron accumulation in neurodegeneration, particularly in PLA2G6-associated neurodegeneration, a rare neurodegenerative disease with autosomal recessive inheritance, which belongs to the group of neurodegeneration with brain iron accumulation disorders.

Stress-Induced Premature Senescence Related to Oxidative Stress in the Developmental Programming of Nonalcoholic Fatty Liver Disease in a Rat Model of Intrauterine Growth Restriction

Metabolic syndrome (MetS) refers to cardiometabolic risk factors, such as visceral obesity, dyslipidemia, hyperglycemia/insulin resistance, arterial hypertension and non-alcoholic fatty liver disease (NAFLD). Individuals born after intrauterine growth restriction (IUGR) are particularly at risk of developing metabolic/hepatic disorders later in life. Oxidative stress and cellular senescence have been associated with MetS and are observed in infants born following IUGR. However, whether these mechanisms could be particularly associated with the development of NAFLD in these individuals is still unknown. IUGR was induced in rats by a maternal low-protein diet during gestation versus. a control (CTRL) diet. In six-month-old offspring, we observed an increased visceral fat mass, glucose intolerance, and hepatic alterations (increased transaminase levels, triglyceride and neutral lipid deposit) in male rats with induced IUGR compared with the CTRL males; no differences were found in females. In IUGR male livers, we identified some markers of stress-induced premature senescence (SIPS) (lipofuscin deposit, increased protein expression of p21WAF, p16INK4a and Acp53, but decreased pRb/Rb ratio, foxo-1 and sirtuin-1 protein and mRNA expression) associated with oxidative stress (higher superoxide anion levels, DNA damages, decreased Cu/Zn SOD, increased catalase protein expression, increased nfe2 and decreased keap1 mRNA expression). Impaired lipogenesis pathways (decreased pAMPK/AMPK ratio, increased pAKT/AKT ratio, SREBP1 and PPARγ protein expression) were also observed in IUGR male livers. At birth, no differences were observed in liver histology, markers of SIPS and oxidative stress between CTRL and IUGR males. These data demonstrate that the livers of IUGR males at adulthood display SIPS and impaired liver structure and function related to oxidative stress and allow the identification of specific therapeutic strategies to limit or prevent adverse consequences of IUGR, particularly metabolic and hepatic disorders.

Lactobacillus brevis MTCC 1750 enhances oxidative stress resistance and lifespan extension with improved physiological and functional capacity in Caenorhabditis elegans via the DAF-16 pathway

Redox imbalance plays a crucial role in the development of age-related diseases, and resistance to oxidative stress is crucial for optimum longevity and healthy aging. Using the wild-type, mutant and transgenic strains, this study explored the antioxidative potential and lifespan extension benefits of different Lactobacillus strains in Caenorhabditis elegans (C. elegans). We observed that Lactobacillus brevis MTCC 1750 could enhance the resistance of C. elegans against juglone induced oxidative stress by reducing its intracellular reactive oxygen species (ROS) accumulation. Also, live L. brevis MTCC 1750 could prolong the worm's lifespan. These effects are dependent on transcription factor DAF-16 evident with significant upregulation of its target gene sod-3. This also explained the significant improvements in different age-associated changes in physiological and mechanical parameters of the worm by L. brevis MTCC 1750. Further investigations revealed that DAF-16 activation and, its enhanced translocation in the nucleus is independent of DAF-2 or JNK pathway. These findings highlighted L. brevis MTCC 1750 as a potent anti-oxidant source for complementing current antioxidant therapeutic strategies. Nonetheless, the findings showed how different signaling events are regulated based on an organism's diet component, and their consequences on the aging process in multiple species.

Remofuscin induces xenobiotic detoxification via a lysosome-to-nucleus signaling pathway to extend the Caenorhabditis elegans lifespan

Lipofuscin is a representative biomarker of aging that is generated naturally over time. Remofuscin (soraprazan) improves age-related eye diseases by removing lipofuscin from retinal pigment epithelium (RPE) cells. In this study, the effect of remofuscin on longevity in Caenorhabditis elegans and the underlying mechanism were investigated. The results showed that remofuscin significantly (p < 0.05) extended the lifespan of C. elegans (N2) compared with the negative control. Aging biomarkers were improved in remofuscin-treated worms. The expression levels of genes related to lysosomes (lipl-1 and lbp-8), a nuclear hormone receptor (nhr-234), fatty acid beta-oxidation (ech-9), and xenobiotic detoxification (cyp-34A1, cyp-35A1, cyp-35A2, cyp-35A3, cyp-35A4, cyp-35A5, cyp-35C1, gst-28, and gst-5) were increased in remofuscin-treated worms. Moreover, remofuscin failed to extend the lives of C. elegans with loss-of-function mutations (lipl-1, lbp-8, nhr-234, nhr-49, nhr-8, cyp-35A1, cyp-35A2, cyp-35A3, cyp-35A5, and gst-5), suggesting that these genes are associated with lifespan extension in remofuscin-treated C. elegans. In conclusion, remofuscin activates the lysosome-to-nucleus pathway in C. elegans, thereby increasing the expression levels of xenobiotic detoxification genes resulted in extending their lifespan.

Microscopic Findings in the Cardiac Muscle of Stranded Extreme Deep-Diving Cuvier's Beaked Whales (Ziphius cavirostris)

Considerable information has been gained over the last few decades on several disease processes afflicting free-ranging cetaceans from a pathologist's point of view. Nonetheless, there is still a dearth of studies on the hearts of these species. For this reason, we aimed to improve our understanding of cardiac histological lesions occurring in free-ranging stranded cetaceans and, more specifically, in deep-diving Cuvier's beaked whales. The primary cardiac lesions that have been described include vascular changes, such as congestion, edema, hemorrhage, leukocytosis, and intravascular coagulation; acute degenerative changes, which consist of contraction band necrosis, wavy fibers, cytoplasmic hypereosinophilia, and perinuclear vacuolization; infiltration of inflammatory cells; and finally, the presence and/or deposition of different substances, such as interstitial myoglobin globules, lipofuscin pigment, polysaccharide complexes, and intra- and/or extravascular gas emboli and vessel dilation. This study advances our current knowledge about the histopathological findings in the cardiac muscle of cetaceans, and more specifically, of Cuvier's beaked whales.

General Rehabilitation Program after Knee or Hip Replacement Significantly Influences Erythrocytes Oxidative Stress Markers and Serum ST2 Levels

The survival of erythrocytes in the circulating blood depends on their membranes' structural and functional integrity. One of the mechanisms that may underlie the process of joint degeneration is the imbalance of prooxidants and antioxidants, promoting cellular oxidative stress. The study is aimed at observing the effects of the 21-day general rehabilitation program on the erythrocytes redox status and serum ST2 marker in patients after knee or hip replacement in the course of osteoarthritis. Erythrocytes and serum samples were collected from 36 patients. We analyzed the selected markers of the antioxidant system in the erythrocytes: catalase (CAT), glutathione reductase (glutathione disulfide reductase (GR, GSR)), total superoxide dismutase activity (SOD), glutathione peroxidase (GPx), glutathione transferase (GST) activity, and cholesterol and lipofuscin (LPS) concentration. In serum, we analyzed the concentration of the suppression of tumorigenicity 2 (ST2) marker. After the 21-day general rehabilitation program, the total SOD and GPx activity, measured in the hemolysates, significantly increased (p < 0.001) while LPS, cholesterol, and ST2 levels in serum significantly decreased (p < 0.001). General rehabilitation reduces oxidative stress in patients after knee or hip replacement in the course of osteoarthritis. Individually designed, regular physical activity is the essential element of the postoperative protocol, which improves the redox balance helping patients recover after the s4urgery effectively.

Assessing age-related heart changes by comparing cases of sudden death during bathing and control cases in Japan

We analyzed 400 deaths that occurred in the bathtub during a 10-year period in the central area of Kanagawa prefecture in Japan. There were 72 (18%) medico-legal autopsy cases. The average age at death was 76.4 ± 11.9 years. Drowning (n = 21, 70.8%) was the most common cause of death in the 72 autopsy cases. The study examined the bodies of 40 cases within a postmortem interval of 3 days. The mean age of the 40 cases of sudden death during bathing was 68.6 ± 12.5 years. Results revealed cardiac hypertrophy in 12 cases (30%), lipofuscin deposition in 39 cases (97.5%), basophilic degeneration in 12 cases (30%), anisocytosis of the nucleus of myocardial cells in 18 cases (45%), perivascular fibrosis in 17 cases (42.5%), amyloid deposits in 1 case, and aortic valve calcification in 1 case. The hearts of control subjects who had lived to 20-99 years were also examined; the frequency of each change was higher in people older than 70 years. There was no statistically significant difference in age-related cardio-pathological changes between cases of sudden death during bathing in people in their 70s and controls in their 70s. It can be concluded that this age-related histopathological index is not related to sudden death during bathing. A large number of elderly people, including those without heart disease, have died during bathing. Preventive measures against sudden death during bathing are strongly recommended, e.g., elderly people should not be left totally unsupervised while they bathe.

Hornerin deposits in neuronal intranuclear inclusion disease: direct identification of proteins with compositionally biased regions in inclusions

Neuronal intranuclear inclusion disease (NIID) is a neurodegenerative disorder, characterized by the presence of eosinophilic inclusions (NIIs) within nuclei of central and peripheral nervous system cells. This study aims to identify the components of NIIs, which have been difficult to analyze directly due to their insolubility. In order to establish a method to directly identify the components of NIIs, we first analyzed the huntingtin inclusion-rich fraction obtained from the brains of Huntington disease model mice. Although the sequence with expanded polyglutamine could not be identified by liquid-chromatography mass spectrometry, amino acid analysis revealed that glutamine of the huntingtin inclusion-rich fraction increased significantly. This is compatible with the calculated amino acid content of the transgene product. Therefore, we applied this method to analyze the NIIs of diseased human brains, which may have proteins with compositionally biased regions, and identified a serine-rich protein called hornerin. Since the analyzed NII-rich fraction was also serine-rich, we suggested hornerin as a major component of the NIIs. A specific distribution of hornerin in NIID was also investigated by Matrix-assisted laser desorption/ionization imaging mass spectrometry and immunofluorescence. Finally, we confirmed a variant of hornerin by whole-exome sequencing and DNA sequencing. This study suggests that hornerin may be related to the pathological process of this NIID, and the direct analysis of NIIs, especially by amino acid analysis using the NII-rich fractions, would contribute to a deeper understanding of the disease pathogenesis.

Histopathological correlation of near infrared autofluorescence in human cadaver coronary arteries

BACKGROUND AND AIMS

Prior coronary optical coherence tomography (OCT)-near infrared auto-fluorescence (NIRAF) imaging data has shown a correlation between high-risk morphological features and NIRAF signal intensity. This study aims to understand the histopathological origins of NIRAF in human cadaver coronary arteries.

METHODS

Ex vivo intracoronary OCT-NIRAF imaging was performed on coronary arteries prosected from 23 fresh human cadaver hearts. Arteries with elevated NIRAF were formalin-fixed and paraffin-embedded. Microscopic images of immunostained Glycophorin A (indicating intraplaque hemorrhage) and Sudan Black (indicating ceroid after fixation) stained slides were compared with confocal NIRAF images (ex. 635 nm, em. 655-755 nm) from adjacent unstained slides in each section. Different images from the same section were registered via luminal morphology. Confocal NIRAF-positive 45° sectors were compared to immunohistochemistry and colocalization between NIRAF and intraplaque hemorrhage or ceroid was quantified by Manders' overlap and Dice similarity coefficients.

RESULTS

Thirty-one coronary arteries from 14 hearts demonstrated ≥1.5 times higher NIRAF signal than background, and 429 sections were created from them, including 54 sections (12.6%) with high-risk plaques. Within 112 confocal NIRAF-positive 45° sectors, 65 sectors (58.0%) showed both Glycophorin A-positive and Sudan Black-positive, while 7 sectors (6.3%) and 40 sectors (33.6%) only showed Glycophorin A-positive or Sudan black-positive, respectively. A two-tailed McNemar's test showed that Sudan Black more closely corresponded to confocal NIRAF than Glycophorin A (p < 1.0 × 10^-6). NIRAF was also found to spatially associate with both Glycophorin A and Sudan Black, with stronger colocalization between Sudan Black and NIRAF (Manders: 0.19 ± 0.15 vs. 0.13 ± 0.14, p < 0.005; Dice: 0.072 ± 0.096 vs. 0.060 ± 0.090, p < 0.01).

CONCLUSIONS

As ceroid associates with oxidative stress and intraplaque hemorrhage is implicated in rapid lesion progression, these results suggest that NIRAF provides additional, complementary information to morphologic imaging that may aid in identifying high-risk coronary plaques via translatable intracoronary OCT-NIRAF imaging.

Analysis of age-related left ventricular collagen remodeling in living donors: Implications in arrhythmogenesis

Age-related fibrosis in the left ventricle (LV) has been mainly studied in animals by assessing collagen content. Using second-harmonic generation microscopy and image processing, we evaluated amount, aggregation and spatial distribution of LV collagen in young to old pigs, and middle-age and elder living donors. All collagen features increased when comparing adult and old pigs with young ones, but not when comparing adult with old pigs or middle-age with elder individuals. Remarkably, all collagen parameters strongly correlated with lipofuscin, a biological age marker, in humans. By building patient-specific models of human ventricular tissue electrophysiology, we confirmed that amount and organization of fibrosis modulated arrhythmia vulnerability, and that distribution should be accounted for arrhythmia risk assessment. In conclusion, we characterize the age-associated changes in LV collagen and its potential implications for ventricular arrhythmia development. Consistency between pig and human results substantiate the pig as a relevant model of age-related LV collagen dynamics.

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Collagen remodeling traits change from youth to adulthood, not from midlife onwards

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In humans, collagen remodeling traits relate with the biological age-pigment lipofuscin

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Beyond collagen amount, its distribution also influences ventricular arrhythmogenesis

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Consistent age-related remodeling was observed amid healthy farm pigs and living donors

Chimeric Mouse With Humanized Liver Is an Appropriate Animal Model to Investigate Mode of Action for Porphyria-Mediated Hepatocytotoxicity

Porphyrinogenic compounds are known to induce porphyria-mediated hepatocellular injury and subsequent regenerative proliferation in rodents, ultimately leading to hepatocellular tumor induction. However, an appropriate in vivo experimental model to evaluate an effect of porphyrinogenic compounds on human liver has not been fully established. Recently, the chimeric mouse with humanized liver (PXB mice) became widely used as a humanized model in which human hepatocytes are transplanted. In the present study, we examined the utility of PXB mice as an in vivo experimental model to evaluate the key events of the porphyria-mediated cytotoxicity mode of action (MOA) in humans. The treatment of PXB mice with 5-aminolevulinic acid, a representative porphyrinogenic compound, for 28 days caused protoporphyrin IX accumulation, followed by hepatocyte necrosis, increased mitosis, and an increase in replicative DNA synthesis in human hepatocytes, indicative of cellular injury and regenerative proliferation, similar to findings in patients with porphyria or experimental porphyria models and corresponding to the key events of the MOA for porphyria-mediated hepatocellular carcinogenesis. We conclude that the PXB mouse is a useful model to evaluate the key events of the porphyria-mediated cytotoxicity MOA in humans and suggest the utility of PXB mice for clarifying the human relevancy of findings in mice.

Reducing lipofuscin accumulation and cardiomyocytic senescence of aging heart by enhancing autophagy

Cardiomyocytes are particularly prone to lipofuscin accumulation. In the aging heart, lipofuscin accumulation is augmented. This study examined distribution of lipofuscin and senescent cardiomyocytes and evaluated improvement of lipofuscin accumulation and cardiomyocytic senescence of the aging heart after treatment with rapamycin. The results of Schmorl staining, Sudan black staining and autofluorescence detection showed that there was more lipofuscin in the myocardium of the ventricles especially in the left ventricle. The conductive tissue contained less lipofuscin than the myocardium. In the aged hearts, lipofuscin accumulation and senescent cardiomyocytes were increased, and the level of autophagy was reduced. In double staining of Sudan black B and senescence-associated β-galactosidase, 10%-20% lipofuscin-loaded cardiomyocytes became senescent. All senescent cardiomyocytes contained lipofuscin deposits. After enhancing autophagy with feed of rapamycin for six months, lipofuscin accumulation and senescence of cardiomyocytes were improved in old rats. Colocalization of autophagic structure and lipofuscin as well as electron micrographs showed that some lipofuscin-loaded lysosomes were sequestrated by autophagic structures. This study suggests that rapamycin-enhanced autopahgy is effective for reducing lipofuscinogenesis and promoting degradation of lipofuscin. Therefore, enhancing autophagy is a novel therapy for alleviating lipofuscin accumulation and myocardial senescence.

Remodeling of t-system and proteins underlying excitation-contraction coupling in aging versus failing human heart

It is well established that the aging heart progressively remodels towards a senescent phenotype, but alterations of cellular microstructure and their differences to chronic heart failure (HF) associated remodeling remain ill-defined. Here, we show that the transverse tubular system (t-system) and proteins underlying excitation-contraction coupling in cardiomyocytes are characteristically remodeled with age. We shed light on mechanisms of this remodeling and identified similarities and differences to chronic HF. Using left ventricular myocardium from donors and HF patients with ages between 19 and 75 years, we established a library of 3D reconstructions of the t-system as well as ryanodine receptor (RyR) and junctophilin 2 (JPH2) clusters. Aging was characterized by t-system alterations and sarcolemmal dissociation of RyR clusters. This remodeling was less pronounced than in HF and accompanied by major alterations of JPH2 arrangement. Our study indicates that targeting sarcolemmal association of JPH2 might ameliorate age-associated deficiencies of heart function.

Investigation of oxidative stress enzymes and histological alterations in tilapia exposed to chlorpyrifos

Chlorpyrifos (ChF) is an organophosphate pesticide that is widely used in agricultural fields and indoor for controlling pests. Aquatic ecosystems are the recipients of various pesticide residues due to leaching spray drift and agricultural runoff and pose toxicity for aquatic organisms. Therefore, the current study was designed to investigate the oxidative stress enzymes and histological alterations in the vital organs of tilapia due to ChF exposure. LC50 (24 h) was calculated as 52.78 μg/l by exposing tilapia with different acute concentrations of ChF. For assessment of sub-lethal toxicity of ChF, the fish were divided into four groups (ChF1, ChF2, ChF3, and control group). ChF1 group was treated with 1/15th of LC50, whereas ChF2 and ChF3 groups were treated with 1/10th and 1/5th of LC50, respectively for 14 days. After that, ChF induced changes in oxidative stress enzymes and histological alterations were evaluated. It was found that the level of glutathione S-transferase (GST), catalase (CAT), and superoxide dismutase (SOD) increased significantly in the liver of ChF-treated tilapia. Histological study of liver tissues showed an increased number of Kupffer cells, hydropic degeneration, necrosis, and hemorrhage. In the spleen of treated fish, increased melanomacrophage centers, necrosis, and congestion were detected. Disorganized muscle fibers, cardiac muscle fiber degeneration, and coagulative necrosis were observed in the heart of ChF-treated fish. It is concluded that sub-lethal concentrations of ChF can induce oxidative stress and histological alterations in the tissues of tilapia.

Terminally Differentiated CD4+ T Cells Promote Myocardial Inflammaging

The cardiovascular and immune systems undergo profound and intertwined alterations with aging. Recent studies have reported that an accumulation of memory and terminally differentiated T cells in elderly subjects can fuel myocardial aging and boost the progression of heart diseases. Nevertheless, it remains unclear whether the immunological senescence profile is sufficient to cause age-related cardiac deterioration or merely acts as an amplifier of previous tissue-intrinsic damage. Herein, we sought to decompose the causality in this cardio-immune crosstalk by studying young mice harboring a senescent-like expanded CD4+ T cell compartment. Thus, immunodeficient NSG-DR1 mice expressing HLA-DRB1*01:01 were transplanted with human CD4+ T cells purified from matching donors that rapidly engrafted and expanded in the recipients without causing xenograft reactions. In the donor subjects, the CD4+ T cell compartment was primarily composed of naïve cells defined as CCR7+CD45RO-. However, when transplanted into young lymphocyte-deficient mice, CD4+ T cells underwent homeostatic expansion, upregulated expression of PD-1 receptor and strongly shifted towards effector/memory (CCR7- CD45RO+) and terminally-differentiated phenotypes (CCR7-CD45RO-), as typically seen in elderly. Differentiated CD4+ T cells also infiltrated the myocardium of recipient mice at comparable levels to what is observed during physiological aging. In addition, young mice harboring an expanded CD4+ T cell compartment showed increased numbers of infiltrating monocytes, macrophages and dendritic cells in the heart. Bulk mRNA sequencing analyses further confirmed that expanding T-cells promote myocardial inflammaging, marked by a distinct age-related transcriptomic signature. Altogether, these data indicate that exaggerated CD4+ T-cell expansion and differentiation, a hallmark of the aging immune system, is sufficient to promote myocardial alterations compatible with inflammaging in juvenile healthy mice.

Mitochondria and Calcium Homeostasis: Cisd2 as a Big Player in Cardiac Ageing

The ageing of human populations has become a problem throughout the world. In this context, increasing the healthy lifespan of individuals has become an important target for medical research and governments. Cardiac disease remains the leading cause of morbidity and mortality in ageing populations and results in significant increases in healthcare costs. Although clinical and basic research have revealed many novel insights into the pathways that drive heart failure, the molecular mechanisms underlying cardiac ageing and age-related cardiac dysfunction are still not fully understood. In this review we summarize the most updated publications and discuss the central components that drive cardiac ageing. The following characters of mitochondria-related dysfunction have been identified during cardiac ageing: (a) disruption of the integrity of mitochondria-associated membrane (MAM) contact sites; (b) dysregulation of energy metabolism and dynamic flexibility; (c) dyshomeostasis of Ca²⁺ control; (d) disturbance to mitochondria–lysosomal crosstalk. Furthermore, Cisd2, a pro-longevity gene, is known to be mainly located in the endoplasmic reticulum (ER), mitochondria, and MAM. The expression level of Cisd2 decreases during cardiac ageing. Remarkably, a high level of Cisd2 delays cardiac ageing and ameliorates age-related cardiac dysfunction; this occurs by maintaining correct regulation of energy metabolism and allowing dynamic control of metabolic flexibility. Together, our previous studies and new evidence provided here highlight Cisd2 as a novel target for developing therapies to promote healthy ageing

Lipofuscin in keratinocytes: Production, properties, and consequences of the photosensitization with visible light

A dysfunction in the mitochondrial-lysosomal axis of cellular homeostasis is proposed to cause cells to age quicker and to accumulate lipofuscin. Typical protocols to mediate lipofuscinogenesis are based on the induction of the senescent phenotype either by allowing many consecutive cycles of cell division or by treating cells with physical/chemical agents such as ultraviolet (UV) light or hydrogen peroxide. Due to a direct connection with the physiopathology of age-related macular degeneration, lipofuscin that accumulates in retinal pigment epithelium (RPE) cells have been extensively studied, and the photochemical properties of RPE lipofuscin are considered as standard for this pigment. Yet, many other tissues such as the brain and the skin may prompt lipofuscinogenesis, and the properties of lipofuscin granules accumulated in these tissues are not necessarily the same as those of RPE lipofuscin. Here, we present a light-induced protocol that accelerates cell aging as judged by the maximization of lipofuscinogenesis. Photosensitization of cells previously incubated with nanomolar concentrations of 1,9-dimethyl methylene blue (DMMB), severely and specifically damages mitochondria and lysosomes, leading to a lipofuscin-related senescent phenotype. By applying this protocol in human immortalized non-malignant keratinocytes (HaCaT) cells, we observed a 2.5-fold higher level of lipofuscin accumulation compared to the level of lipofuscin accumulation in cells treated with a typical UV protocol. Lipofuscin accumulated in keratinocytes exhibited the typical red light emission, with excitation maximum in the blue wavelength region (~450 nm). Fluorescence lifetime image microscopy data showed that the keratinocyte lipofuscin has an emission lifetime of ~1.7 ns. Lipofuscin-loaded cells (but not control cells) generated a substantial amount of singlet oxygen (¹O₂) when irradiated with blue light (420 nm), but there was no ¹O₂ generation when excitation was performed with a green light (532 nm). These characteristics were compared with those of RPE cells, considering that keratinocyte lipofuscin lacks the bisretinoids derivatives present in RPE lipofuscin. Additionally, we showed that lipofuscin-loaded keratinocytes irradiated with visible light presented critical DNA damages, such as double-strand breaks and Fpg-sensitive sites. We propose that the DMMB protocol is an efficient way to disturb the mitochondrial-lysosomal axis of cellular homeostasis, and consequently, it can be used to accelerate aging and to induce lipofuscinogenesis. We also discuss the consequences of the lipofuscin-induced genotoxicity of visible light in keratinocytes.

Mini-Review on Lipofuscin and Aging: Focusing on The Molecular Interface, The Biological Recycling Mechanism, Oxidative Stress, and The Gut-Brain Axis Functionality

Intra-lysosomal accumulation of the autofluorescent "residue" known as lipofuscin, which is found within postmitotic cells, remains controversial. Although it was considered a harmless hallmark of aging, its presence is detrimental as it continually accumulates. The latest evidence highlighted that lipofuscin strongly correlates with the excessive production of reactive oxygen species; however, despite this, lipofuscin cannot be removed by the biological recycling mechanisms. The antagonistic effects exerted at the DNA level culminate in a dysregulation of the cell cycle, by inducing a loss of the entire internal environment and abnormal gene(s) expression. Additionally, it appears that a crucial role in the production of reactive oxygen species can be attributed to gut microbiota, due to their ability to shape our behavior and neurodevelopment through their maintenance of the central nervous system.

General, 21-Day Postoperative Rehabilitation Program Has Beneficial Effect on Oxidative Stress Markers in Patients after Total Hip or Knee Replacement

Imbalance in prooxidant-antioxidant equilibrium plays an important role in the progression of osteoarthritis (OA). Postoperative rehabilitation significantly improves the functional activity of patients with OA. We aimed to assess the effect of the general 21-day postoperative rehabilitation on the oxidative stress markers in patients after total hip arthroplasty or knee replacement. Patients (n =41) started individually designed postoperative rehabilitation ca. 90 days after endoprosthesis implantation. We used the six-minute walk test (6MWT) to quantify the changes in their exercise capacity. We analyzed the oxidative stress markers: total antioxidant capacity (TAC), total superoxide dismutase (SOD), Cu-Zn-superoxide dismutase (CuZnSOD) and ceruloplasmin (Cp) activity, malondialdehyde (MDA) and lipofuscin (LPS) concentration in patients serum to asses changes in the oxidative stress intensity. We found that after 21-days postoperative rehabilitation program: the average distance walked by patients increased by 69 m; TAC increased by 0.20 ± 0.14 mmol/l; both SOD isoforms activities increased by 1.6 (±1.7) and 1.72 (±1.5) NU/ml, respectively; but Cp activity decreased by 1.8 (0.7-3.7) mg/dl. Also, we observed lower concentrations of lipid peroxidation markers: by 19.6 ± 24.4 μmol/l for MDA and by 0.4 ± 0.5 RF for LPS. A 21-day postoperative rehabilitation program effectively reduces oxidative processes, which helps the patients after total hip or knee replacement in a successful recovery.

Molecular Perspectives of Mitochondrial Adaptations and Their Role in Cardiac Proteostasis

Mitochondria are the key to properly functioning energy generation in the metabolically demanding cardiomyocytes and thus essential to healthy heart contractility on a beat-to-beat basis. Mitochondria being the central organelle for cellular metabolism and signaling in the heart, its dysfunction leads to cardiovascular disease. The healthy mitochondrial functioning critical to maintaining cardiomyocyte viability and contractility is accomplished by adaptive changes in the dynamics, biogenesis, and degradation of the mitochondria to ensure cellular proteostasis. Recent compelling evidence suggests that the classical protein quality control system in cardiomyocytes is also under constant mitochondrial control, either directly or indirectly. Impairment of cytosolic protein quality control may affect the position of the mitochondria in relation to other organelles, as well as mitochondrial morphology and function, and could also activate mitochondrial proteostasis. Despite a growing interest in the mitochondrial quality control system, very little information is available about the molecular function of mitochondria in cardiac proteostasis. In this review, we bring together current understanding of the adaptations and role of the mitochondria in cardiac proteostasis and describe the adaptive/maladaptive changes observed in the mitochondrial network required to maintain proteomic integrity. We also highlight the key mitochondrial signaling pathways activated in response to proteotoxic stress as a cellular mechanism to protect the heart from proteotoxicity. A deeper understanding of the molecular mechanisms of mitochondrial adaptations and their role in cardiac proteostasis will help to develop future therapeutics to protect the heart from cardiovascular diseases.