Oxidative stress, resulting from an imbalance between reactive oxygen species (ROS) production and the antioxidant defense system, plays a central role in the pathophysiology of numerous diseases, including cardiovascular, neurodegenerative, and inflammatory disorders. This review explores the biochemical mechanisms of ROS-induced damage to lipids, proteins, cholesterol, and DNA, and analyzes both endogenous (enzymatic and non-enzymatic) and exogenous (nutritional) antioxidant systems that counteract oxidative damage. Key enzymes such as superoxide dismutase, catalase, and glutathione peroxidase, alongside dietary antioxidants like vitamins C and E, polyphenols, and carotenoids, are highlighted for their protective roles. The dual antioxidant/pro-oxidant behavior of these compounds under varying physiological conditions is discussed. Furthermore, this paper reviews the cellular repair systems activated in response to oxidative injury and the biomarkers used to assess oxidative stress in clinical settings. Special attention is given to the implications of oxidative stress in cardiovascular and autoimmune diseases and the potential of antioxidant strategies in disease prevention and therapy. The findings underscore the importance of maintaining redox homeostasis and support further research into antioxidant-based interventions.

Drug induced fatty liver disease (DIFLD) is a form of drug-induced liver injury (DILI), which can also be included in the more general metabolic dysfunction-associated steatotic liver disease (MASLD), which specifically refers to the accumulation of fat in the liver unrelated to alcohol intake. A bi-directional relationship between DILI and MASLD is likely to exist: while certain drugs can cause MASLD by acting as pro-steatogenic factors, MASLD may make hepatocytes more vulnerable to drugs. Having a pre-existing MASLD significantly heightens the likelihood of experiencing DILI from certain medications. Thus, the prevalence of steatosis within DILI may be biased by pre-existing MASLD, and it can be concluded that the genuine true incidence of DIFLD in the general population remains unknown. In certain individuals, drug-induced steatosis is often accompanied by concomitant injury mechanisms such as oxidative stress, cell death, and inflammation, which leads to the development of drug-induced steatohepatitis (DISH). DISH is much more severe from the clinical point of view, has worse prognosis and outcome, and resembles MASH (metabolic-associated steatohepatitis), as it is associated with inflammation and sometimes with fibrosis. A literature review of clinical case reports allowed us to examine and evaluate the clinical features of DIFLD and their association with specific drugs, enabling us to propose a classification of DIFLD drugs based on clinical outcomes and pathological severity: Group 1, drugs with low intrinsic toxicity (e.g., ibuprofen, naproxen, acetaminophen, irinotecan, methotrexate, and tamoxifen), but expected to promote/aggravate steatosis in patients with pre-existing MASLD; Group 2, drugs associated with steatosis and only occasionally with steatohepatitis (e.g., amiodarone, valproic acid, and tetracycline); and Group 3, drugs with a great tendency to transit to steatohepatitis and further to fibrosis. Different mechanisms may be in play when identifying drug mode of action: (1) inhibition of mitochondrial fatty acid β-oxidation; (2) inhibition of fatty acid transport across mitochondrial membranes; (3) increased de novo lipid synthesis; (4) reduction in lipid export by the inhibition of microsomal triglyceride transfer protein; (5) induction of mitochondrial permeability transition pore opening; (6) dissipation of the mitochondrial transmembrane potential; (7) impairment of the mitochondrial respiratory chain/oxidative phosphorylation; (8) mitochondrial DNA damage, degradation and depletion; and (9) nuclear receptors (NRs)/transcriptomic alterations. Currently, the majority of, if not all, adverse outcome pathways (AOPs) for steatosis in AOP-Wiki highlight the interaction with NRs or transcription factors as the key molecular initiating event (MIE). This perspective suggests that chemical-induced steatosis typically results from the interplay between a chemical and a NR or transcription factors, implying that this interaction represents the primary and pivotal MIE. However, upon conducting this exhaustive literature review, it became evident that the current AOPs tend to overly emphasize this interaction as the sole MIE. Some studies indeed support the involvement of NRs in steatosis, but others demonstrate that such NR interactions alone do not necessarily lead to steatosis. This view, ignoring other mitochondrial-related injury mechanisms, falls short in encapsulating the intricate biological mechanisms involved in chemically induced liver steatosis, necessitating their consideration as part of the AOP’s map road as well.

The diagnosis of inherited metabolic disorders is a long and tedious process. The matching of clinical data with a genomic variant in a specific metabolic pathway is an essential step, but the link between a genome and the clinical data is normally difficult, primarily for new missense variants or alterations in intron sequences. Notwithstanding, elucidation of the pathogenicity of a specific variant might be critical for an accurate diagnosis. In this study, we described a novel intronic variant c.2597 + 5G > T in the donor splice sequence of the PHKA2 gene. To investigate PHKA2 mRNA splicing, as well as the functional consequences on glycogen metabolism, we generated hepatocyte-like cells from a proband’s fibroblasts by direct reprogramming. We demonstrated an aberrant splicing of PHKA2, resulting in the incorporation of a 27 bp upstream of intron 23 into exon 23, which leads to an immediate premature STOP codon. The truncated protein was unable to phosphorylate the PYGL protein, causing a 4-fold increase in the accumulation of glycogen in hepatocyte-like cells. Collectively, the generation of personalized hepatocyte-like cells enabled an unequivocal molecular diagnosis and qualified the sister’s proband, a carrier of the same mutation, as a candidate for a preimplantation genetic diagnosis. Additionally, our direct reprogramming strategy allows for an unlimited source of “diseased” hepatocyte-like cells compatible with high-throughput platforms.

Childhood obesity represents a growing global public health crisis, strongly driven by the widespread consumption of sugar-sweetened beverages (SSBs) and, increasingly, artificially sweetened beverages (ASBs). SSB intake drives excessive calorie consumption, reduces satiety, and disrupts hormones, leading to metabolic dysfunction such as insulin resistance and type 2 diabetes. Despite some regional declines, global consumption of SSBs remains high, with persistent socioeconomic disparities. Concurrently, ASBs, marketed as healthier alternatives, pose emerging metabolic and behavioral risks, such as gut microbiota disruption and altered appetite regulation, raising concerns about their long-term safety. Both beverage types displace nutritionally balanced food options in children’s diets and foster enduring preferences for sweetness, exacerbating poor dietary quality. Public health interventions targeting SSB reduction have demonstrated modest success; however, rising ASB use complicates prevention strategies. Effective mitigation of childhood obesity requires comprehensive approaches that emphasize reducing all sweetened beverage consumption, promoting water and whole-food hydration, and addressing the behavioral and environmental factors underlying unhealthy beverage choices to improve lifelong health outcomes.

Human hepatic organoids derived from pluripotent or adult stem cells offer powerful platforms for disease modeling and drug discovery. However, developing robust and scalable organoids capable of sustaining long-term functionality remains challenging. Here, we developed a novel, semi-defined approach using a self-assembling peptide and collagen I to create highly uniform human induced pluripotent stem cell-derived hepatic organoids in droplet format, which we term hepatic organobodies (OBs). This method enabled rapid, reproducible production of threedimensional (3D) liver tissues, which remained structurally, metabolically, and functionally stable for several weeks. OBs adopted hallmark hepatic morphology and expressed key hepatocyte genes, several at levels approaching freshly isolated primary human hepatocytes (PHHs). OBs secreted substantially higher albumin and A1AT compared with parallel two dimensional cultures, and transcriptomic profiling revealed marked enhancement of hepatic maturation, including elevated expression of CYP3A4, CYP2C9 , and CYP1A2 , and enrichment of PPAR signaling and fatty acid β -oxidation pathways. Additionally, OBs exhibited drug metabolizing activity comparable to classical Matrigel-based organoids and demonstrated CYP3A4 and CYP2C9 activities comparable to the ‘gold standard’ 3D PHH microtissues. Critically, OBs accurately predicted hepatotoxicity of more than 10 reference compounds, outperforming HepG2 cells and matching PHH-based benchmarks. Overall, we present OBs, a novel, and scalable 3D liver model that delivers advanced maturation and robust metabolic function. This platform offers a powerful and reproducible alternative to existing organoid systems as it avoids animal-derived, undefined matrices such as Matrigel, requires no specialized equipment, and relies on rapid self-curation of the hydrogel triggered by physiological salt concentrations, making the process fast, reproducible, broadly accessible, and scalable.