Biology subjects

Velagapudi, V.

Publications and source records attributed to Velagapudi, V..

4 recordsLinked to original sources

bioRxiv2024

Taurine/chenodeoxycholic acid ratio as a circulating biomarker of insidious vitamin B12 deficiency in humans

Deficiency of vitamin B12 (B12), an essential water-soluble vitamin, leads to irreversible neurological damage, osteoporosis, cardiovascular diseases, and anemia. Clinical tests to detect B12deficiency lack specificity and sensitivity. B12 deficiency is thus insidious because progressive decline in organ functions may go unnoticed until the damage is advanced or irreversible. Here, using targeted unbiased metabolomic profiling in the sera of B12-deficient versus control individuals, we set out to identify biomarker(s) of B12 deficiency. Metabolomic profiling identified 77 metabolites, and Partial least squares discriminant-analysis (PLS-DA) and hierarchical clustering analysis (HCA) showed a differential abundance in B12-deficient sera of taurine, xanthine, hypoxanthine, chenodeoxycholic acid, neopterin, and glycocholic acid. Random forest (RF) multivariate analysis identified a taurine/chenodeoxycholic acid ratio, with an AUC score of 1, to be the best biomarker to predict B12 deficiency. Mechanistically, B12 deficiency reshaped the transcriptomic and metabolomic landscape of the cell identifying a downregulation of methionine, taurine, urea cycle, and nucleotide metabolism, and an upregulation of Krebs cycle. Thus, we propose taurine/chenodeoxycholic acid ratio in serum as a potential biomarker of B12 deficiency in humans and elucidate cellular metabolic pathways regulated by B12 deficiency.

pharmacology and toxicology↗

bioRxiv2021

S. Typhimurium impairs glycolysis-mediated acidification of phagosomes to evade macrophage defense

Regulation of the cellular metabolism is now recognized as a crucial mechanism for the homeostasis of innate and adaptive immune cells upon diverse extracellular stimuli. Macrophages, for instance, increase glycolysis upon stimulation with pathogen-associated molecular patterns (PAMPs). Conceivably, pathogens also counteract these metabolic changes for their own survival in the host. However, despite this dynamic interplay in host-pathogen interactions, the role of immunometabolism in the context of intracellular bacterial infections is still unclear. Here, employing unbiased metabolomic and transcriptomic approaches, we investigated the role of metabolic adaptations of macrophages upon Salmonella enterica serovar Typhimurium (S. Typhimurium) infections. Importantly, our results suggested that S. Typhimurium abrogates glycolysis and its modulators such as insulin-signaling to impair macrophage defense. Mechanistically, glycolytic enzyme aldolase A is critical for v-ATPase assembly and the acidification of phagosomes upon S. Typhimurium infection, and impairment in the glycolytic machinery eventually leads to decreased bacterial clearance and antigen presentation in macrophages. Collectively, our results highlight a vital molecular link between metabolic adaptation and phagosome maturation in macrophages, which is targeted by S. Typhimurium to evade cell-autonomous defense.

microbiology↗

bioRxiv2020

Interactive effects of aging and aerobic capacity on energy metabolism-related metabolites of serum, skeletal muscle, and white adipose tissue

Aerobic capacity is a strong predictor of longevity. With aging, aerobic capacity decreases concomitantly with changes in whole body metabolism leading to increased disease risk. To address the role of aerobic capacity, aging and their interaction on metabolism, we utilized rat models of low and high intrinsic aerobic capacity (LCRs/HCRs) and assessed the metabolomics of serum, muscle, and white adipose tissue (WAT). We compared LCRs and HCRs at two time points: Young rats were sacrificed at 9 months, and old rats were sacrificed at 21 months. Targeted and semi-quantitative metabolomics analysis was performed on ultra-pressure Liquid Chromatography Tandem Mass Spectrometry (UPLC-MS) platform. Interaction of aerobic capacity and aging was studied via regression analysis. Our results showed at young age, metabolites linked to amino acid metabolism differed in serum and muscle with aerobic capacity, whereas no difference were observed in WAT. In aged animals, most prominent changes in metabolites occurred in WAT. Aerobic capacity and aging interactively affected seven metabolites linked to energy metabolism. Our results support previous findings that high aerobic capacity is associated with more efficient amino acid metabolism in muscle. While impaired branched chain amino acids (BCAAs) and fatty acid metabolism in the muscle may associate to the high risk of metabolic disorders and shorter lifespan previously observed in LCRs. The interactive effects of aging and aerobic capacity on energy metabolism-related metabolites were largely driven by HCRs, reflecting the importance of inherited aerobic capacity in the aging process. Our results highlight that dysfunctional mitochondrial {beta}-oxidation in WAT may be one key mechanism related to aging.

molecular biology↗

bioRxiv2018

Validation and automation of a high-throughput multi-targeted method for semi-quantification of endogenous metabolites from different biological matrices using tandem mass spectrometry

The use of metabolomics profiling to understand metabolism under different physiological states has increased in recent years, which created the need for robust analytical platforms. Here, we present a validated method for targeted and semi-quantitative analysis of 102 polar metabolites that covers major metabolic pathways from 24 classes in a single 17.5-min assay. The method has been optimized for a wide range of biological matrices from various organisms, and involves automated sample preparation, and data processing using in-house developed R package. To ensure reliability, the method was validated for accuracy, precision, selectivity, specificity, linearity, recovery, and stability according to European Medicines Agency guidelines. We demonstrated excellent repeatability of the retention times (CV<4%), calibration curves (R2[≥]0.980) in their respective wide dynamic concentration ranges (CV<3%), and concentrations (CV<25%) of quality control samples interspersed within 25 batches analyzed over a period of one-year. The robustness was demonstrated through high correlation between metabolite concentrations measured using our method and NIST reference values (R2=0.967), including cross-platform comparability against the BIOCRATES AbsoluteIDQp180 kit (R2=0.975) and NMR analyses (R2=0.884). We have shown that our method can be successfully applied in many biomedical research fields and clinical trials, including epidemiological studies for biomarker discovery. In summary, a thorough validation demonstrated that our method is reproducible, robust, reliable, and suitable for metabolomics studies.

biochemistry↗