Reducing the mitochondrial oxidative burden alleviates lipid-induced muscle insulin resistance in humans

Age-Related Oxidative Stress and Mitochondrial Dysfunction in Lymph Node Stromal Cells Limit the Peripheral T Cell Homeostatic Maintenance and Function

Lymph nodes (LN) are the key organs in charge of long-term maintenance of naïve lymphocytes and their initial, primary activation upon infection. Accumulating evidence indicates that LN stromal cells undergo degenerative changes with aging that critically impair LN function, including the generation of protective primary immune responses. The nature of these defects remains incompletely understood. We here demonstrate that age-related LN stromal changes manifest themselves in mitochondrial dysfunction and oxidative stress. Ex vivo, all three major stromal cell subsets, fibroblastic reticular cells (FRC), lymphatic endothelial cells (LEC), and blood endothelial cells (BEC) exhibit elevated mitochondrial reactive oxygen species (ROS) stress, reduced mitochondrial potential, and elevated mitochondrial mass with aging. Old FRC also exhibited elevated cytoplasmic ROS production. This was accompanied by the reduced ability of old LN stromal cells to support Tn survival in vitro, a defect alleviated by pretreating old LN stroma with the general antioxidant N-acetyl cysteine (NAC) as well as by mitochondrial ROS-reducing (mitoquinone) and mitophagy-inducing (urolithin A) compounds. Mitochondrial dysfunction and, in particular, reduced mitochondrial potential in old FRC were also seen upon vaccination or infection in vivo. Consistent with these results, in vivo antioxidant treatment of old mice with NAC restored to adult levels the numbers of antigen-specific CD8+ effector T cells and their production of granzyme B in response to antigenic challenge.

The Ferroptosis-Mitochondrial Axis in Depression: Unraveling the Feedforward Loop of Oxidative Stress, Metabolic Homeostasis Dysregulation, and Neuroinflammation

Emerging evidence links ferroptosis-mitochondrial dysregulation to depression pathogenesis through an oxidative stress-energy deficit-neuroinflammation cycle driven by iron overload. This study demonstrates that iron accumulation initiates ferroptosis via Fenton reaction-mediated lipid peroxidation, compromising neuronal membrane integrity and disabling the GPx4 antioxidant system. Concurrent mitochondrial complex I/IV dysfunction impairs ATP synthesis, creating an AMPK/mTOR signaling imbalance and calcium dyshomeostasis that synergistically impair synaptic plasticity. Bidirectional crosstalk emerges: lipid peroxidation derivatives oxidize mitochondrial cardiolipin, while mitochondrial ROS overproduction activates ACSL4 to amplify ferroptotic susceptibility, forming a self-reinforcing neurodegenerative loop. Prefrontal-hippocampal metabolomics reveal paradoxical metabolic reprogramming with glycolytic compensation suppressing mitochondrial biogenesis (via PGC-1α/TFAM downregulation), trapping neurons in bioenergetic crisis. Clinical data further show that microglial M1 polarization through cGAS-STING activation sustains neuroinflammation via IL-6/TNF-α release. We propose a "ferroptosis-mitochondrial fragmentation-metabolic maladaptation" triad as mechanistic subtyping criteria for depression. Preclinical validation shows that combinatorial therapy (iron chelators + SIRT3 agonists) rescues neuronal viability by restoring mitochondrial integrity and energy flux. This work shifts therapeutic paradigms from monoaminergic targets toward multimodal strategies addressing iron homeostasis, organelle dynamics, and metabolic vulnerability-a framework with significant implications for developing neuroprotective antidepressants.

Synergistic effects of lead and copper co-exposure on promoting oxidative stress and apoptosis in the neuronal cells

Exposure to lead (Pb) or copper (Cu) is common and has been associated with increased risk of neurodegenerative disease. However, combined neurotoxic effects of co-exposure to these elements remain unclear. This study aimed to determine the toxic effects of Pb and Cu co-exposure on HT22 cells. In this study, Pb and Cu co-exposure exhibited enhanced toxicity, including increased reactive oxygen species (ROS) and Malondialdehyde (MDA) levels, Superoxide Dismutase 1 (SOD1) activity, lower cell viability and higher apoptotic rates, compared to single-element exposure. Pb and Cu co-exposure also resulted in significantly increased cellular labile Cu level by altering the protein levels of Cu transporters, including Copper Transporter-1 (CTR1), ATPase Copper Transporting-α(ATP7A) and ATPase Copper Transporting-β (ATP7B). Treating with antioxidants or Cu chelator to the co-exposed cells blocked the reduction cell viability and elevation of apoptotic rates. This study suggests that Pb and Cu co-exposure can result in a synergistic toxicity in neuronal cells by inducing oxidative stress and apoptosis. The cellular Cu accumulation may play an important role in inducing these synergistic effects, and both antioxidation and Cu chelation may be promising control measures to alleviate the neurotoxicity of Pb and Cu co-exposure.

Integrated Metabolomics and Lipidomics Analysis Reveals the Mechanism Behind the Action of Chiglitazar on the Protection Against Sepsis-Induced Acute Lung Injury

Background: Sepsis-induced acute lung injury (SALI) is a critical clinical challenge with high mortality. Metabolic dysregulation drives SALI pathogenesis, disrupting lung function and energy metabolism. Despite proven benefits, metabolic restoration is underused in sepsis. This study explores chiglitazar's role in balancing metabolism to protect against SALI. Methods: The protective effects of chiglitazar in CLP rats were demonstrated by the survival curve, histological analysis, and immunohistochemical analysis in the lung tissue. Metabolomic and lipidomic analyses of lung tissue samples using gas chromatography-mass spectrometry (GC-MS) and liquid chromatography-mass spectrometry (LC-MS) were performed to evaluate metabolic shifts induced by CLP surgery and chiglitazar pretreatment. The mRNA and protein levels of the underlying targets directing nicotinamide adenine dinucleotide (NAD+) and triglyceride synthesis were analyzed by qPCR and Western blotting. To validate the mechanism by which chiglitazar protected against SALI, the SIRT1 inhibitor EX-527 was applied to human normal lung epithelial (BEAS-2B) cells and another batch of rats to observe its reverse effect against chiglitazar's action. Results: Chiglitazar pretreatment significantly restored NAD+ and improved dysregulated lipid metabolism by enhancing the synthesis of triglycerides (TGs) and suppressing accumulated fatty acids (FAs). The metabolic modulation mediated by chiglitazar was associated with the upregulations of the SIRT1/PGC-1α/PPARα/GPAT3 axis. Co-treatment with EX-527 in LPS-stimulated BEAS-2B cells and CLP rats inhibited the effects of chiglitazar on the aforementioned signaling pathways and worsened the protective effects of chiglitazar on lung injury, respectively. Conclusions: Chiglitazar alleviates SALI by restoring NAD+ and TG synthesis, highlighting the balancing of metabolism as a promising therapeutic strategy in the management of SALI.

Activation of SIK1 by phanginin A regulates skeletal muscle glucose uptake by phosphorylating HADC4/5/7 and enhancing GLUT4 expression and translocation

Salt-inducible kinase 1 (SIK1) participates in various physiological processes, yet its involvement in regulating skeletal muscle glucose uptake remains unclear. Previously, we showed that phanginin A, a natural compound isolated from Caesalpinia sappan Linn, activated SIK1 to suppress gluconeogenesis in hepatocytes. Here, we aimed to elucidate the effects of SIK1 on skeletal muscle glucose uptake by using phanginin A. The C2C12 myotubes were incubated with phanginin A and then glucose uptake, mRNA levels, membrane GLUT4 content, phosphorylation levels of proteins in SIK1/HDACs and Akt/AS160 signaling pathways were determined. Phanginin A significantly promoted glucose uptake, while the pan-SIK inhibitor or knocking down SIK1 expression abolished the promotion. Further exploration showed that phanginin A enhanced GLUT4 mRNA levels by increasing histone deacetylase (HDAC) 4/5 phosphorylation and MEF2a mRNA and protein level, and knocking down SIK1 blocked these effects. Additionally, phanginin A induced HDAC7 phosphorylation, upregulated the junction plakoglobin (JUP) expression and Akt/AS160 phosphorylation. Knocking down JUP or SIK1 both attenuated the phanginin A-induced Akt/AS160 signaling and glucose uptake, suggesting that activation of SIK1 by phanginin A inactivated HDAC7 to increase JUP expression and Akt/AS160 phosphorylation, led to upregulation of GLUT4 translocation and glucose uptake. In vivo study showed that phanginin A increased phosphorylation levels of SIK1, HDAC4/5/7, Akt/AS160, and gene expression of MEF2a, GLUT4 and JUP, accompanied by elevated membrane GLUT4 and glycogen content in gastrocnemius muscle of C57BL/6 J mice, indicating enhanced glucose utilization. These findings reveal a novel mechanism that SIK1 activation by phanginin A stimulates skeletal muscle glucose uptake through phosphorylating HADC4/5/7 and the subsequent enhancement of GLUT4 expression and translocation.

Role of oxidative balance score in staging and mortality risk of cardiovascular-kidney-metabolic syndrome: Insights from traditional and machine learning approaches

OBJECTIVES

To evaluate the roles of oxidative balance score (OBS) in staging and mortality risk of cardiovascular-kidney-metabolic syndrome (CKM).

METHODS

Data of this study were from the National Health and Nutrition Examination Survey 1999-2018. We performed cross-sectional analyses using multinomial logistic regression to investigate the relationship between OBS and CKM staging. Cox proportional hazards models were used to assess the impact of OBS on mortality outcomes in CKM patients. Additionally, mediation analyses were performed to explore whether OBS mediated the relationships between specific predictors (Life's Simple 7 score [LS7], systemic immune-inflammation index [SII], frailty score) and mortality outcomes. Then, machine learning models were developed to classify CKM stages 3/4 and predict all-cause mortality, with SHapley Additive exPlanations values used to interpret the contribution of OBS components.

RESULTS

21,609 participants were included (20,319 CKM, median [IQR] age: 52.0 [38.0-65.0] years, 54.3% male, median [IQR] follow-up: 9.4 [5.3-14.1] years). Lower OBS quartiles were associated with advanced CKM staging. Moreover, lower OBS quartiles were related to increased mortality risk, compared to Q4 of OBS (all-cause mortality: Q1: HR 1.31, 95% CI 1.18-1.46, Q2: HR 1.27, 95% CI 1.14-1.42, Q3: HR 1.18, 95% CI 1.06-1.32; cardiovascular mortality: Q1: HR 1.44, 95% CI 1.16-1.79, Q2: HR 1.39, 95% CI 1.11-1.74, Q3: HR 1.26, 95% CI 1.01-1.57; non-cardiovascular mortality, Q1: HR 1.27, 95% CI 1.12-1.44, Q2: HR 1.23, 95% CI 1.08-1.40, Q3: HR 1.16, 95% CI 1.02-1.31), with optimal risk stratification threshold for OBS was 22. Additionally, OBS mediated (ranging 4.25%-32.85 %) effects of SII, LS7, frailty scores on mortality outcomes. Moreover, light gradient boosting machine achieved the highest performance for predicting advanced CKM staging (area under curve: 0.905) and all-cause mortality (area under curve: 0.875). Cotinine increased risk, while magnesium, vitamin B6, physical activity were protective.

CONCLUSIONS

This study highlights OBS as a risk stratification tool for CKM, emphasizing oxidative stress's role in CKM staging and mortality risk management.

More comprehensive relationship between eGDR and sarcopenia in China: a nationwide cohort study with national representation

INTRODUCTION

Although studies had shown that Insulin resistance (IR) was correlated with the occurrence of sarcopenia, there were still many controversial conclusions. Therefore, we conducted a more comprehensive study on the relationship between the estimated glucose disposal rate (eGDR), an alternative indicator of IR, and the risk of sarcopenia, muscle mass, and muscle strength to clarify their interactions.

METHODS

The Study included individuals from The China Health and Retirement Longitudinal Study (CHARLS) who had complete eGDR data at baseline and did not develop low muscle mass and low muscle strength. The individuals were divided into four subgroups based on the quartile (Q) of the eGDR. The lowest quartile (Q1) of the eGDR was used as a reference. Logistic regression and linear regression were used to evaluate the relationship between eGDR and sarcopenia (low muscle mass, low muscle strength, possible sarcopenia, and sarcopenia) and sarcopenia related features (ASM/Ht2, grip, and RMS), respectively. In addition, we further evaluated the nonlinear relationship using smooth curve fitting and threshold effect analysis.

RESULTS

The results showed that after adjusting for confounders, eGDR was negatively associated with the risk of sarcopenia and positively associated with sarcopenia related characteristics. In addition, men showed a more significant reduction in the likelihood of low muscle mass compared to women. But as eGDR levels rise, women gain more ASM/Ht2. Further nonlinear analysis revealed an inverse correlation between eGDR and ASM/Ht2 at the inflection point of 15.3893. Besides that, eGDR was positively correlated with grip (7.1862) and RMS (11.1042) before the inflection point.

CONCLUSIONS

The study found that higher levels of eGDR were associated with a lower risk of developing sarcopenia. However, the effects of eGDR on muscle mass and muscle strength need to be considered comprehensively. For muscle mass, it is recommended to maintain eGDR below 15.3893, and for muscle strength, it is recommended to maintain eGDR below 7.1862, with more potential benefits for early warning of sarcopenia.