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Biology subjects

Stevens, T. L.

Publications and source records attributed to Stevens, T. L..

2 recordsLinked to original sources

Thirty days of supplementation with PQQ reprograms immunometabolic networks in Western diet-fed female baboons

Western-style diets promote chronic metabolic inflammation and dyslipidemia, yet safe interventions that restore immunometabolic homeostasis remain limited. Pyrroloquinoline quinone (PQQ) is a naturally occurring redox cofactor with antioxidant and metabolic regulatory properties, but its systemic effects in translational preclinical models are poorly defined. Here, we examined the impact of short-term PQQ supplementation in obese adult female olive baboons (Papio anubis) chronically fed a Western diet. Using a human-equivalent dose administered for 30 days, we found that PQQ supplementation significantly reduced circulating markers of systemic inflammation and cholesterol in Western-diet-fed animals, lowering circulating C-reactive protein, soluble CD163, and atherogenic lipoprotein fractions independent of changes in adiposity. Proteomic and pathway analyses of circulating proteins in plasma and serum revealed suppression of complement, thrombo-inflammatory, and extracellular matrix remodeling pathways, alongside enhanced lipoprotein assembly, remodeling, and clearance. Network analyses identified restoration of neurotrophic tyrosine kinase receptor 1 (NTRK1)- and forkhead box A2 (FOXA2)-regulated signaling as central features of the PQQ response, accompanied by inhibition of pro-fibrotic, xenobiotic, and inflammatory pathways, as well as predicted activation of liver X receptor (LXR)- and insulin growth factor (IGF)-associated metabolic programs. These findings demonstrate that PQQ rapidly reprograms systemic immunometabolic networks in a nonhuman primate model of diet-induced metabolic stress, highlighting FOXA2- and neurotrophin-associated pathways as novel targets of PQQs action.

physiology↗

Ultrastructure analysis of mitochondria, lipid droplet and sarcoplasmic reticulum apposition in human heart failure

BackgroundCardiomyocyte structural remodeling is reported as a causal contributor to heart failure (HF) development and progression. Growing evidence highlights the role of organelle apposition in cardiomyocyte function and homeostasis. Disruptions in organelle crosstalk, such as that between the sarcoplasmic reticulum (SR) and mitochondria, are thought to impact numerous cellular processes such as calcium handling and cellular bioenergetics; two processes that are disrupted and implicated in cardiac pathophysiology. While the physical distance between organelles is thought to be essential for homeostatic cardiomyocyte function, whether the interactions and coupling of organelles are altered in human heart failure remains unclear. MethodsHere, we utilized transmission electron microscopy and careful quantification of ultrastructure to characterize the changes in organelle apposition in cardiomyocytes isolated from the hearts of patients diagnosed with various types of HF. Subsequently we employed molecular approaches to examine the expression of proposed organelle tethers. ResultsWe demonstrate that cardiomyocytes isolated from dilated cardiomyopathy, hypertrophic cardiomyopathy and ischemic cardiomyopathy hearts display smaller, more rounded mitochondria, as compared to nonfailing controls. Failing cardiomyocytes also exhibited disrupted SR-mitochondria juxtaposition and changes in the expression of proposed molecular tethers. Further analysis revealed alterations in lipid droplet dynamics including decreased lipid droplet content and less lipid droplets in association with mitochondria in failing cardiomyocytes. ConclusionHere we observed changes in organelle dynamics in cardiomyocytes isolated from heart failure patients diagnosed with differing etiologies. Our results suggest that organelle structure and apposition may be a ubiquitous contributor to human HF progression. RESEARCH PERSPECTIVEWhat is New? O_LIWe provide a detailed analysis of organelle apposition in human heart failure, which has been understudied, and report that that failing human cardiomyocytes display an increase in distance between mitochondria and both the sarcoplasmic reticulum and lipid droplets. C_LIO_LIStructural changes in organelles are correlated with the expression of proposed organelle tethers. C_LIO_LIResource of ultrastructural changes in organelle apposition in human heart failure resulting from various etiologies. C_LI What Questions Should be Addressed next? O_LIThe results from this study provide rationale for causal experimentation to elucidate the contribution of organelle apposition to the progression of heart failure. Future studies examining mechanisms of mitochondrial tethering to the SR or lipid droplet will evaluate specific targets for therapeutic application. C_LI

cell biology↗