PBMC transcriptome reveals an early metabolic risk profile in young rats with metabolically obese, normal-weight phenotype

Metabolically obese, normal-weight (MONW) phenotype is characterized by visceral adiposity and obesity-related complications despite the absence of excess body weight. Early identification of this phenotype is crucial to establish preventive strategies. We aim to validate the utility of peripheral blood mononuclear cells (PBMC) transcriptome to detect metabolic risk related to the MONW phenotype at early life stages (young adulthood). Male Wistar rats were pair-fed either standard (NW group) or a high-fat diet (MONW group) after weaning, until 3.5 months. Global gene expression was examined by microarray in PBMC, and specific genes of interest by RT-qPCR in PBMC and liver. Results were validated in adult 6-month-old MONW rats. Young MONW animals had similar weight to controls (NW group) but greater adiposity, including liver fat content, and insulin resistance signs. PBMC transcriptome distinguished clearly MONW from NW rats. Neurological pathways were affected in line with impaired cognition in these animals. Most top-regulated genes were related to inflammation, including the top-up and down-regulated genes, Hpgds and Slfn4. Expression of fatty liver-related genes like Mkrn1 and Nampt was also affected in PBMC of the young MONW group mirroring liver alteration. Slfn4 and Mkrn1 appeared as especially relevant biomarkers with altered expression also in PBMC of adult 6-month-old MONW rats. In conclusion, PBMC transcriptomic analysis emerges as a tool for identifying early biomarkers of obesity-related metabolic risk in young and apparently healthy (lean) subjects, pointing towards increased inflammation, liver fat deposition, and cognitive alterations.