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

Cardiac cell senescence: molecular mechanisms, key proteins and therapeutic targets

Cardiac aging, particularly cardiac cell senescence, is a natural process that occurs as we age. Heart function gradually declines in old age, leading to continuous heart failure, even in people without a prior history of heart disease. To address this issue and improve cardiac cell function, it is crucial to investigate the molecular mechanisms underlying cardiac senescence. This review summarizes the main mechanisms and key proteins involved in cardiac cell senescence. This review further discusses the molecular modulators of cellular senescence in aging hearts. Furthermore, the discussion will encompass comprehensive descriptions of the key drugs, modes of action and potential targets for intervention in cardiac senescence. By offering a fresh perspective and comprehensive insights into the molecular mechanisms of cardiac senescence, this review seeks to provide a fresh perspective and important theoretical foundations for the development of drugs targeting this condition.

Ameliorative effects of Bifidobacterium longum peptide-1 on benzo(α)pyrene induced oxidative damages via daf-16 in Caenorhabditis elegans

Oxidative stress is implicated in numerous diseases, with benzo(α)pyrene (BaP) known for causing substantial oxidative damage. Bifidobacterium longum (B. longum) is recognized as an antioxidant bacterium for certain hosts, yet its influence on oxidative damages instigated by BaP remains undetermined. In our study, we introduced various strains of Caenorhabditis elegans (C. elegans) to BaP to trigger oxidative stress, subsequently treating them with different forms of B. longum to evaluate its protective effects. Additionally, we explored the role of daf-16 in this context. Our findings indicated that in wild-type N2 C. elegans, B. longum-even in the form of inactivated bacteria or bacterial ultrasonic lysates (BULs)-significantly extended lifespan. BaP exposure notably decreased lifespan, superoxide dismutase (SOD) activity, and motility, while simultaneously down-regulating the expression of reactive oxygen species (ROS)-associated genes (sod-3, sek-1, cat-1) and daf-16 downstream genes (sod-3, ctl-2). However, it significantly increased the ROS level, malondialdehyde (MDA) content, and lipofuscin accumulation and up-regulated another daf-16 downstream gene (clk-1) (P <0.05). Interestingly, when further treated with B. longum peptide-1 (BLP-1), opposite effects were observed, and all the aforementioned indices changed significantly. In the case of RNAi (daf-16) C. elegans, BaP exposure significantly shortened the lifespan (P <0.05), which was only slightly prolonged upon further treatment with BLP-1. Furthermore, the expression of daf-16 downstream genes showed minor alterations in RNAi C. elegans upon treatment with either BaP or BLP-1. In conclusion, our findings suggest that B. longum acts as a probiotic for C. elegans. BLP-1 was shown to safeguard C. elegans from numerous oxidative damages induced by BaP, but these protective effects were contingent upon the daf-16 gene.

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.

Increased serum lipofuscin associated with leukocyte telomere shortening in veterans: a possible role for sulfur mustard exposure in delayed-onset accelerated cellular senescence

BACKGROUND

Sulfur mustard (SM) is a toxic gas that causes chronic inflammation and oxidative stress leading to cell senescence. This study aimed to evaluate two indicators of biological aging (i.e., serum lipofuscin level and leukocyte telomere length) and assess their relationship based on the severity of SM exposure in the long term.

METHODS

The study was performed on two groups of male participants. 1) SM-exposed group (exposed to SM once in 1987), 73 volunteers. 2) Non-exposed group, 16 healthy volunteers. The SM-exposed group was categorized into three subgroups based on the severity of SM exposure and body damage (asymptom, mild, and severe). The blood sample was prepared from members of each group. The serum lipofuscin, TGF-β, malondialdehyde (MDA), c-reactive protein (CRP), and leukocyte telomere length (TL) were measured in all participants.

RESULTS

The MDA level was increased in the SM-exposed group (mean = 39.6 µM, SD = 16.5) compared to the non-exposed group (mean = 21.1 µM, SD = 10.3) (P < 0.05). The CRP level was also increased in the SM-exposed group (mean = 5.12 mg/l, SD = 3.36) compared to the non-exposed group (mean = 3.51 mg/l, SD = 1.21), while the TGF-β level was decreased (P < 0.05) in the SM-exposed group (mean = 52.6 pg/ml, SD = 18.7) compared to the non-exposed group (mean = 68.9 pg/ml, SD = 13.8). The relative TL was shorter in the SM-exposed group (mean = 0.40, SD = 0.28) than in the non-exposed group (mean = 2.25, SD = 1.41) (P < 0.05). The lipofuscin level was higher in the total SM-exposed group (mean = 1.44 ng/ml, SD = 0.685) than in the non-exposed group (mean = 0.88 ng/ml, SD = 0.449) (P < 0.05). The MDA and CRP levels were increased in the SM-exposed subgroups of asymptom, mild, and severe than the non-exposed group, while TGF-β level and TL were decreased in those subgroups. The lipofuscin level was higher in the SM-exposed subgroups of mild and severe than in the non-exposed group. The regression analysis determined a negative correlation between lipofuscin level and TL. The lipofuscin/TL ratio was higher in the total SM-exposed group (mean = 6.36, SD = 5.342) than in the non-exposed group (mean = 0.51, SD=0.389). This ratio was also higher in the SM-exposed subgroups of asymptom, mild, and severe than in the non-exposed group. The lipofuscin/TL ratio did not differ between mild and severe subgroups.

CONCLUSION

The delayed toxicity of SM is associated with chronic oxidative stress, continuous inflammatory stimulation, increased lipofuscin, and telomere shortening. Future studies are needed to verify the suitability of serum lipofuscin to telomere length ratio in determining the severity of SM toxicity.

A High-Fat and High-Carbohydrate Diet Promotes Reminiscent Hallmarks of an Aging Ovary in the Rabbit Model

The primary definition of ovarian aging refers to the loss of follicles. Moreover, the aging of the microenvironment in ovaries, specifically affecting the follicles, may reveal deterioration with advancing age. Besides aging, metabolic disorders associated with hypercaloric diets may affect ovarian health and manifest characteristics associated with premature aging. In this study, we used 10-week-old chinchilla rabbits fed with a high-fat and high-carbohydrate diet (HFCD) until 25 weeks of age to explore hallmarks of reminiscent ovarian aging. The HFCD diet appeared to affect the ovarian reserve, reflected in a significant decrease in primordial follicles. Likewise, Sudan black stain detection revealed substantial differences in the deposits of lipofuscin in the interstitial glands of HFCD-fed rabbits compared to controls, constituting a "hallmark" of aging. The HFCD showed no induced changes in the expression of SOD 2 in the interstitial gland; however, surface epithelium cells were greater expressed. Besides this, the HFCD induced nuclear translocation of NF-ΚΒ p65 factor transcription in surface epithelium cells. We conclude that an HFCD induces a greater accumulation of senescence cells in the interstitial gland, promoting characteristics reminiscent of ovarian aging. However, the activation mechanism of NF-KB caused by an HFCD, which may be stress-responsive and generated by the interstitial gland, requires further study.

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.

Recent advances in the therapeutic potential of emodin for human health

Emodin (1,3,8-trihydroxy-6-methylanthraquinone) is a bioactive compound, a natural anthraquinone aglycone, present mainly in herbaceous species of the families Fabaceae, Polygonaceae and Rhamnaceae, with a physiological role in protection against abiotic stress in vegetative tissues. Emodin is mainly used in traditional Chinese medicine to treat sore throats, carbuncles, sores, blood stasis, and damp-heat jaundice. Pharmacological research in the last decade has revealed other potential therapeutic applications such as anticancer, neuroprotective, antidiabetic, antioxidant and anti-inflammatory. The present study aimed to summarize recent studies on bioavailability, preclinical pharmacological effects with evidence of molecular mechanisms, clinical trials and clinical pitfalls, respectively the therapeutic limitations of emodin. For this purpose, extensive searches were performed using the PubMed/Medline, Scopus, Google scholar, TRIP database, Springer link, Wiley and SciFinder databases as a search engines. The in vitro and in vivo studies included in this updated review highlighted the signaling pathways and molecular mechanisms of emodin. Because its bioavailability is low, there are limitations in clinical therapeutic use. In conclusion, for an increase in pharmacotherapeutic efficacy, future studies with carrier molecules to the target, thus opening up new therapeutic perspectives.

Viability assessment using fluorescent markers and ultrastructure of human biopsied embryos vitrified in open and closed systems

RESEARCH QUESTION

Are there any differences in viability and ultrastructure amongst embryos biopsied on Day 5 versus Day 3 following vitrification in open and closed systems and compared to fresh embryos?

DESIGN

One hundred human embryos (40 blastocysts biopsied on Day 5 and subsequently vitrified in open or closed systems and 60 Day 3 biopsied embryos that developed to blastocysts but were rejected for transfer following preimplantation genetic testing for monogenic/single gene defects and for aneuploidies were either treated fresh [n = 20] or vitrified [n = 40] in open or closed systems) and following warming and culture for 4 h were subjected to viability staining with carboxyfluorescein-diacetate succinimidylester/propidium iodide or processed for transmission electron microscopy.

RESULTS

No statistically significant differences were observed in the viability of human biopsied embryos following vitrification in open and closed systems. Compared to fresh embryos, vitrified ones had a higher incidence of damage (propidium iodide-stained cells) irrespective of the vitrification method (P = 0.005). These damaged cells were more prominent in Day 5 biopsied blastocysts and mainly located at the position of cutting. Characteristic lipofuscin droplets (representative of apoptosis) and a higher number of vacuoles and distension of mitochondria were also more evident in vitrified embryos, although this was not statistically assessed.

CONCLUSIONS

Vitrification in open and closed systems does not adversely affect the viability and ultrastructure of Day 5 and Day 3 biopsied embryos as revealed by the minimal yet statistically significant cell damage observed. This damage may be compensated by the embryos, which in their attempt to fully recover following vitrification, potentially enable 'rescue' processes to eliminate it.