Purpose: Aging is a complex biological process that begins at the cellular level, disrupting energy homeostasis. This study investigated the role of Sirt3, major mitochondrial deacetylase involved in metabolic pathways, in sex-dependent changes in energy homeostasis during aging in kidney of Sirt3 WT and KO mice.

Methods: Enzymatic activity, lipid peroxidation, protein carbonylation with Western blot and metabolomic analyses were performed to assess physiological and metabolic parameters

Results: Higher Sirt3 expression in male WT mice leads to increased vulnerability to its deficiency, as reflected in the shorter lifespan of male KO mice. This is further supported by distinct metabolomic clustering in male KO mice, highlighting significant metabolic disruptions. Male-specific declines in metabolites such as creatine, phosphorylcholine, trimethylamine-N-oxide, and L-carnitine, along with reduced trifunctional multienzyme complex subunit β (HADHB) expression, point to impaired fatty acid metabolism and mitochondrial dysfunction.

Conclusions: The findings emphasize the sex-specific function of Sirt3 in regulating mitochondrial activity, energy metabolism, and oxidative stress in the murine kidney, with male mice exhibiting a greater reliance on Sirt3 for metabolic stability.

Many animal species are remarkably resilient to the harmful conditions of hypoxia and reoxygenation, a phenomenon widely observed across many species and environmental settings. The ability to survive oxygen deprivation and reintroduction without significant cellular damage is partially attributed to the upregulation of antioxidants, a strategy termed "Preparation for Oxidative Stress" (POS). The concept of POS is that by producing more antioxidants under hypoxia animals would anticipate the eventual and potentially damaging reintroduction of oxygen. Historically, the specific mechanisms through which POS is activated remained elusive. Over the past decade, significant advancements have been made in understanding POS at a molecular level and in identifying its widespread in the animal kingdom. Notably, a detailed molecular mechanism for the activation of POS under conditions of low oxygen availability has been proposed, emphasizing the role of reactive oxygen species in modulating antioxidant response through redox-sensitive transcription factors. Furthermore, recent research has demonstrated the occurrence of POS in free-ranging animals under completely natural settings, confirming its ecological and physiological relevance. Despite recent advancements, some aspects of POS remain underexplored and should be prioritized in future research. These include the experimental validation of the mechanisms proposed to underlie POS and the assessment of the relevance of POS in multi-stressor scenarios, particularly to understand how organisms cope with combined stressors in fluctuating environments.

Regular physical exercise (PE) leads to a systemic adaptation to redox homeostasis perturbation, one of the hallmarks of exercise adaptation. Studies have shown that PE can alter the molecular composition of extracellular vesicles (EVs), impacting their ability to communicate with other cells and modulate physiological processes. EVs circulating in the body and secreted from various cell types, including skeletal muscle cells, contain various regulatory molecules and mediate intercellular communications and tissue cross-talk. Considering that the health-related benefits of a physically active lifestyle are partially driven by various bioactive molecules released into the circulation during exercise, collectively termed “exerkines”, there has been a rapidly growing interest in the role of EVs cargo as “carriers” in the multi-systemic, adaptive response to exercise. Indeed, a potential mechanism by which plasma EVs released during exercise impact ageing and diseases related to redox impairment is increased delivery of redox components, such as redox transcription factors and antioxidants. This presentation will offer a general overview of the biology of exercise-induced EVs and their putative role in health maintenance and disease prevention, with a focus on redox homeostasis control.  

Friedreich's ataxia (FRDA) (OMIM #229300, ORPHA95) is a rare hereditary disease with a prevalence of 1/20,000 to 1/50,000 in the European population. It is classified as a hereditary peripheral neuropathy of a sensory type, with autosomal recessive inheritance. This disease is caused by the deficiency of a mitochondrial protein called frataxin. Lack of expression of this protein produces accumulation of iron, alterations in the biogenesis of iron-sulfur clusters, failures in complexes I, II and III of the respiratory chain and in the activity of the aconitase enzyme, and a reduction in the biosynthesis of the heme groups. As a consequence, finally, an overload of ROS derived from the Fenton reaction occurs. Together with the movement impairment, 60% of FRDA patients suffer cardiomyopathy, which is the most common cause of death in these patients and has no clear explanation of its physiopathological cause. Two iPSC cell lines from FRDA patients with cardiomyopathy) and a control line were differentiated to ventricular cardiomyocytes in our lab.  Both FRDA cell lines showed changes in heartbeat parameters, such as heart rate and amplitude when compared to the control cell line. Also, calcium homeostasis measured by immunofluorescence showed important differences when compared to the control cell line. RT-PCR analyses of miRNAs related to myocardial function also showed clear differences, especially for miR-323-3p and miR-142-3p. Using EM, we found differences in the mitochondrial size, shape and in mitochondrial cristae organization. These results also correlate with changes in the cardiomyocytes cytoskeleton and in the structure of the sarcomeres using confocal microscopy techniques. Our results showed the correlation between mitochondrial changes and the impairment in ventricular cardiomyocytes activity derived from FRDA’s iPS cells.

Mitochondrial production of O₂^•– and H₂O₂ has been implicated in redox signaling and in the pathogenesis of numerous diseases including cancer, neurodegeneration, and cardiovascular diseases. To understand the exact role of those species, new chemical biology tools for selective and efficient induction of mitochondrial superoxide production are needed. Here, we report the development of a new viologen-based redox cycling agent, mito-diquat (Mito-DQ), capable of inducing targeted mitochondrial O₂^•– production at significantly higher rates as compared to previously reported mito-paraquat (Mito-PQ), a widely used chemical tool to study mitochondria-dependent redox signaling.

The in vivo determination of oxidative stress always remains a great challenge. Our approach in Liège CHU consists of simultaneously measuring in blood samples four different kinds of biomarkers: enzymatic and non-enzymatic antioxidants, trace elements, markers of oxidative damage to lipids, and identification of sources leading to increased reactive oxygen species (ROS) production. All these biomarkers (n = 16) have been investigated in patients: 1) with Abdominal Aortic Aneurysm (AAA)¹ or operated for Thoracic Abdominal Dissection (TAD)², 2) suffering from Chronic Obstructive Pulmonary Disease (COPD)³ or FacioScapuloHumeral Myopathy (FSHM)⁴, 3) with COVID-19^5,6 and 4) with delirium⁷. When compared to our internal reference values, depletion in non-enzymatic antioxidants (vitamin C, β-carotene, vitamin C/vitamin E ratio, thiol proteins) and trace elements (zinc, selenium) was observed in the majority of these pathologies. By contrast, increased levels in glutathione peroxidase, copper/zinc ratio, lipid peroxides (ROOH), and myeloperoxidase are common in all these diseases.

Thyroid hormones play an important role in both testis development and spermatogenesis. While hypothyroidism has been known to generally induce metabolic suppression, lower respiration rate, and reduce free radical formation, recent studies reported an increased production of reactive oxygen species (ROS). First line of antioxidant defense in testes is comprised of two isoforms of superoxide dismutase (SOD), CuZnSOD and MnSOD differently localised in cell. This study aimed to investigate the effects of hypothyroidism on the expression, localisation, and activity of these two SOD isoforms during spermatogenesis. Hypothyroidism was induced in two-month-old male Wistar rats by 0.04% methimazole in drinking water for 7, 15, and 21 days, while euthyroid control group drank tap water. CuZnSOD protein expression was decreased after 15 and 21 days while its activity was decreased by 40% in all examined time points of methimazole treatment in comparison to euthyroid control. At the same time, neither MnSOD protein expression nor its activity was changed by treatment. However, cell and stage-specific CuZnSOD and MnSOD immunoexpression in the rat testes were changed in hypothyroidism and may contribute to the altered spermatic characteristics. Our results suggest that changes in CuZnSOD and MnSOD expression play role in redox disbalance leading to hypothyroidism-induced maturation arrest of spermatogenesis.

Dysregulation of the redox system and the interconnected low-level inflammation (LLI) act as a driving force of damaging mechanisms in gestational diabetes mellitus (GDM) and are strongly related to severe obstetric and neonatal complications of hyperglycaemic pregnancies. Major disturbances in microRNA-based mechanism accompany (glyco)oxidative stress ((g)OS), for which reason we hypothesized that microRNAs may serve as sensors and/or effectors of (g)OS/LLI in GDM and we chose candidates for GDM biomarker analysis among known (g)OS/LLI-associated microRNAs. The aim of the study was to analyze the properties of miR-146a-5p and miR-21-5p as redox status indicators in GDM, as well as to compare two different biological samples as sources of potentially relevant GDM biomarkers.  miR-146a-5p and miR-21-5p were quantified by real-time polymerase chain reaction in peripheral blood mononuclear cells of patients with GDM and normoglycaemic pregnant controls (n=40 each), as well as in paired samples of extracellular vesicles (EVs) extracted from serum. Correlation analysis was conducted for the expression levels of tested microRNAs and the activities of glutathione reductase (GR), total superoxide dismutase (SOD), catalase (CAT), concentration of serum thiol groups and the level of Nrf2 mRNA. In both samples, tested microRNAs were upregulated in GDM group, with a more pronounced increase in expression in EVs, compared to peripheral blood mononuclear cells (PBMCs) (1.81 vs. 1.52 fold for miR-146a-5p and 1.98 vs. 1.58 fold for miR-21-5p). There was a significant positive correlation between the expression of miR-21-5p from PBMCs and Nrf2 in both GDM patients and controls, as well as a positive correlation with the activity of total SOD in GDM patients. On the other hand, miR-146a-5p from EVs demonstrated negative correlation with Nrf2 expression and the activity of total SOD. These data demonstrate the potential of (g)OS/LLI-related microRNAs miR-146a-5p and miR-21-5p to serve as indicators of GDM and the associated (g)OS-related changes.

One of the adaptive features that organisms developed throughout their long natural history is the ability to change the activity of cells, tissues, and organs on a daily, 24-hour, basis. These cyclical changes are synchronized to the external environment through a light-dark regime and internal circadian clock. Daily recurring environmental changes are followed by variations in animal behavior and physiology, which include oscillations in neuroendocrine, metabolic, cardiovascular, and immune functions. By transforming the circadian periodicity of day, artificial light from anthropogenic sources might interfere with organisms leading to a disturbance in hormone levels and physiological stress. In this study, we investigated daily natural variations in the antioxidant system and the effects of artificial light on the redox balance in larvae of tree frogs. We compared antioxidant parameters in tadpoles from the natural day/night cycle (control) with ones exposed to artificial light at night (treatment). The antioxidant response was measured at four time points during 24h (morning, day, evening, and night). Our results showed that only GR activity did not display day/night changes nor was affected by night illumination. For GSH-Px and GST we reported changes in activity at different times of day that were in the same manner for both treatment and control. The highest values were in the morning compared to the other time points. Variation during 24h was also observed for SOD, CAT and GSH. However, exposure to night light affected the pattern and intensity of these parameters compared to the control group. Overall our study suggests that daily differences in metabolic activity can result in variations in the antioxidant system and that the presence of artificial light affects these changes. The disrupted natural rhythm of the antioxidant response may further reflect on other physiological processes and lead to a state of oxidative stress.

According to global epidemiology, non-alcoholic fatty liver disease (NAFLD) is the most common chronic liver disease, affecting about a quarter of the adult population worldwide. NAFLD is characterised by the accumulation of triglycerides in hepatocytes (steatosis), which can progress to non-alcoholic steatohepatitis, a more severe form of NAFLD. Oxidative stress is closely linked to the disease progression due to the activation of inflammatory pathways. The aim of this study was to identify markers of redox status that could predict the risk of developing steatosis. The study included 179 participants who underwent ultrasound examination at University Medical Centers Zemun and Zvezdara. Participants were divided into two groups: 119 patients with steatosis and 60 apparently healthy controls (control group, CG). Biochemical markers as well as markers of redox status: total oxidant status (TOS) and total antioxidant status (TAS) were determined in serum spectrophotometrically on biochemical analysers. Univariate and multivariate binary logistic regression analyses were used to test the predictions of TOS and TAS for NAFLD. Patients had higher body mass index (P<0.001), glucose (P<0.001), uric acid (P<0.001), TOS (P=0.007), and TAS (P<0.001) levels compared to CG. Univariate binary regression analysis revealed significant predictive capability of TOS and TAS for NAFLD demonstrated by the following ORs: 1.104 (1.020-1.195) (P=0.014) and 1.003 (1.001-1.004) (P<0.001), respectively. After applying multivariate binary logistic regression analyses (adjustments were made for sex and BMI), TOS and TAS kept independent significant predictive capability for NAFLD, as demonstrated by the following ORs: 1.098 (1.009-1.195) (P=0.030) and 1.002 (1.000-1.003) (P=0.026), respectively. TOS and TAS are positively associated with the risk of developing NAFLD, independent of sex and BMI. Both markers are elevated, probably because increased oxidative activity requires a stronger antioxidant defence response, which should be confirmed by a follow-up study including more participants.