Abstract Metabolic stress is a major determinant of cell fate, particularly during differentiation, when long-lasting adaptations shape cellular responses to subsequent insults. Early-life glycemic instability is increasingly recognized as a stressor capable of programming cardiomyocyte metabolism and vulnerability, yet its direct impact on stress-response pathways during cardiomyocyte differentiation remains poorly defined. Here, we used differentiating H9c2 cardiomyoblasts to model chronic hypoglycemic (2.5 mM), normoglycemic (5 mM), and hyperglycemic (30 mM) conditions as opposing metabolic challenges, and examined their effects on substrate transport, lipid homeostasis, and stress-induced cell death pathways. Both hypoglycemic and hyperglycemic stress reprogrammed phenotypes, but through distinct mechanisms. Hypoglycemic stress increased expression of the glucose transporter GLUT1, concomitantly enhancing functional glucose uptake. It also upregulated the fatty-acid transporter CD36 and carnitine palmitoyltransferase-1 (CPT1), indicating coordinated enhancement of substrate uptake and mitochondrial fatty-acid oxidation. In contrast, hyperglycemic stress suppressed GLUT1 expression and decreased glucose uptake, while increasing CD36 without upregulating CPT1. Under iso-osmotic conditions, this resulted in intracellular lipid accumulation consistent with an overload and lipotoxic stress. When challenged with anoxia–reoxygenation, hypoglycemia-conditioned cells predominantly engaged autophagy, as shown by increased LC3B-II/LC3B-I ratio, whereas hyperglycemia-conditioned cells exhibited enhanced apoptotic signaling, with increased caspase-3, PARP cleavage and DNA fragmentation. Notably, normoglycemic differentiation conferred the greatest resistance to oxygen fluctuations. Together, these findings demonstrate that chronic glycemic stress during cardiomyoblast differentiation programs divergent stress-response pathways, biasing cells toward autophagy or apoptosis in response to acute injury. This work highlights metabolic homeostasis as a critical determinant of cellular stress resilience and provides mechanistic insight into how early metabolic stress shapes cardiomyocyte vulnerability.
Critical care involves the management of organismal stress by sedation. Benzodiazepines remain widely used for anxiolysis and sedation in critical care, including in septic shock. Yet converging mechanistic, preclinical and clinical evidence suggests that benzodiazepines and the endogenous ligand of benzodiazepine-binding sites, the “endozepine” acyl-CoA binding protein/diazepam binding inhibitor (ACBP/DBI), may impair host immune defenses, exacerbate organ dysfunction and contribute to long-term morbidity after intensive care. A unifying framework is that benzodiazepines may accelerate “iatrogenic aging” by antagonizing adaptive stress responses (notably autophagy) and favoring cellular senescence, chronic inflammation, immunosuppression and neurocognitive perturbations. Here, we synthesize evidence supporting benzodiazepine avoidance in sepsis-heavy intensive care populations. We propose that replacing benzodiazepines with alternative sedative strategies may improve both short-term outcomes and long-term trajectories of post-sepsis disability. We hypothesize that post-intensive-care syndrome (PICS), including -as a specific case- post-sepsis syndrome (PSS), is caused by premature aging of the organism and that PICS/PSS might be attenuated by the avoidance of benzodiazepine administration during and after critical care.
Triptolide, an extract from the Chinese herb Thunder God Vine, a compound renowned for its anti-cancer properties, exhibits an elusive mechanism of action. While extensive research has elucidated its direct effects on cancer cells, the indirect impact on non-tumor cells within the cancer microenvironment remains poorly understood. In this study, we investigated the influence of Triptolide on tumor-associated macrophages (TAMs), pivotal contributors to ovarian cancer progression. Using cell culture and promoter assay, cellular viability assessment, cell clock assay, transwell assays, flow cytometry, ELISA, TUNEL staining, and mouse models, we found that Triptolide does not significantly affect macrophage proliferation or survival; instead, it induces differentiation of naive macrophages towards the M1 phenotype and reprograms M2-polarized macrophages into a similar inflammatory state. These observations suggest that modulation of TAMs may partially underlie Triptolide’s hindrance of ovarian cancer progression. Mechanistically, we reveal that Triptolide inhibits Nrf2 transcription - a master regulator governing anti-inflammatory responses in macrophages. Functional gain- and loss-of-function studies further confirmed that Nrf2 inhibition is essential for Triptolide-mediated TAM reprogramming and subsequent suppression of cancer cell progression. Co-culturing with macrophages substantially enhances ovarian cancer cell growth, invasion, and migration; however, all these effects are abrogated by treatment with Triptolide. Collectively, our findings indicate that the suppression of ovarian cancer by Triptolide is mediated in part through its capacity to reprogram TAMs via the Nrf2 pathway.
Geroprotection aims at extending healthspan by delaying age-associated pathologies. Polyamines including spermine and spermidine are interconvertible metabolites whose longevity-promoting effects have traditionally been attributed to autophagy induction. In addition, recent evidence identifies spermine as an endogenous Fe2+ chelator that suppresses ferroptosis, thereby complementing the autophagy-inducing activity of spermidine. Indeed, spermidine inhibits EP300 acetyltransferase activity and supports hypusination-dependent activation of TFEB, both leading to autophagy. However, enhanced autophagic flux may increase susceptibility to ferroptosis through ferritinophagy and lipid remodeling. In parallel, polyamine catabolism generates H2O2 and acrolein, both of which facilitate lipid peroxidation and ferroptotic demise. The discovery that spermine directly chelates redox-active Fe2+ closes a conceptual gap by explaining how polyamine supplementation can promote longevity while avoiding excessive ferroptotic cell loss. Multiple lines of evidence including metabolomics, isotope tracing, cell-free lipid peroxidation systems, Fe2+-binding biophysics, mass spectrometry, Raman spectroscopy, nuclear magnetic resonance and disease models demonstrate that spermine limits labile iron and ferroptosis. Together, these findings support a unified model in which spermidine-driven autophagy and spermine-mediated ferroptosis inhibition cooperate to preserve tissue homeostasis and healthspan.
Arachidonic acid (AA) metabolism plays a critical role in renal cell osmoadaptation. We recently demonstrated that hypertonicity induces the expression and activation of cytosolic phospholipase A2 (cPLA2). On one hand, AA released by cPLA2 enhances triacylglyceride (TG) synthesis and accumulation. On the other hand, AA is converted into prostaglandins (PG) through cyclooxygenase 2 (COX2) activity. Both processes are required for renal cell survival under osmotic stress. However, the mechanisms by which hypertonicity induces cPLA2 expression remain poorly understood. Given that we previously shown that hypertonicity regulates TG synthesis through the IRE1α-XBP1s branch of the unfolded protein response (UPR), here we examined whether XBP1s regulates the cPLA2-AA-COX2 axis in renal cells subjected to osmotic stress. We found that XBP1s modulates hypertonicity-induced expression of cPLA2 and COX2 by increasing NFκB transcriptional activity. Inhibition of IRE1α impaired normal COX2 degradation and disrupted AA metabolism, leading to a decrease in cell viability and preventing hypertonicity-induced epithelial differentiation. Prostaglandin E2 (PGE2) contributed to cell polarization facilitating adherens junction (AJ) assembly. Together, these findings highlight a central role for the IREα-XBP1s-NFκB signaling axis in coordinating cell stress responses and epithelial differentiation through AA metabolism activation.
