Metabolic Responses in Endothelial Cells Following Exposure to Ketone Bodies

Abstract

The ketogenic diet (KD) is a high-fat, low-carbohydrate diet based on the induction of the synthesis of ketone bodies (KB). Despite its widespread use, the systemic impact of KD is not completely understood. The purpose of this study was to evaluate the effects of physiological levels of KB on HMEC-1 endothelial cells. To this aim, DNA oxidative damage and the activation of Nrf2, a known transcriptional factor involved in cell responses to oxidative stress, were assessed. The exposure of cells to KB exerted a moderate genotoxic effect, measured by a significant increase in DNA oxidative damage. However, cells pre-treated with KB for 48 h and subjected to a secondary oxidative insult (H2O2), significantly decreased DNA damage compared to control oxidized cells. This protection occurred by the activation of Nrf2 pathway. In KB-treated cells, we found increased levels of Nrf2 in nuclear extracts and higher gene expression of HO-1, a target gene of Nrf2, compared to control cells. These results suggest that KB, by inducing moderate oxidative stress, activate the transcription factor Nrf2, which induces the transcription of target genes involved in the cellular antioxidant defense system.

Hepatocyte-Macrophage Acetoacetate Shuttle Protects against Tissue Fibrosis

“…However, recurrent boluses of high D-bOHB concentrations may provoke toxic responses in non-macrophages. Indeed, high-concentration bOHB activates pro-inflammatory and oxidative stress in calf hepatocytes and in other cell types (Meroni et al, 2018;Shi et al, 2014). Thus, tissue responses to ketone bodies require attentiveness to (1) distinct cell type responses within a tissue; (2) the delivered AcAc/bOHB ratio (including, but not limited to, mitochondrial redox potential effect); (3) total ketone body concentration and kinetics; and (4) augmenting or competing signals.…”

Investigating Ketone Bodies as Immunometabolic Countermeasures against Respiratory Viral Infections

“…A second mechanism whereby exogenous ketones could mitigate oxidative stress is through upregulation of antioxidant genes. BHB activates the transcription factor Nrf2 to induce antioxidant response element (ARE) gene expression [81][82][83] and induces local histone acetylation at the promoter of oxidative stress resistance genes (Foxo3a and Mt2) by inhibiting activity of histone deacetylases histone deacetylase 1 (HDAC1) and HDAC2. 34,35,84 Both of these actions result in an increased expression of protective genes and cytoprotection, which was demonstrated in two independent studies using the kidney in a mouse model of chemically induced oxidative stress.…”

“…33,81 Similar effects have been further demonstrated in other tissues in multiple preclinical models. 34,35,82,83 Activation of Nrf2 is protective in multiple models of ARDS (reviewed in Liu et al 85 ). However, an inhibitory effect of BHB on HDAC activity may be counterproductive during viral infection.…”

“… 33 , 81 Similar effects have been further demonstrated in other tissues in multiple preclinical models. 34 , 35 , 82 , 83 Activation of Nrf2 is protective in multiple models of ARDS (reviewed in Liu et al. 85 ).…”

Rhus coriaria L. Fruit Extract Prevents UV-A-Induced Genotoxicity and Oxidative Injury in Human Microvascular Endothelial Cells

“…The HMEC-1 cell line (Centers for Disease Control and Prevention, Atlanta, GA, USA) was kindly gifted by Prof. Nicoletta Basilico, Dipartimento di Scienze Biomediche, Chirurgiche e Odontoiatriche, Università degli Studi di Milano (Italy). Cells were grown in MCDB 131 medium (Sigma Aldrich) plus 1% penicillin/streptomycin, 10% fetal bovine serum (FBS), 20 mM HEPES buffer, 1 µg/mL hydrocortisone and 10 ng/mL epidermal growth factor (EGF) [31]. Cells were maintained at 37 • C in a 5% CO 2 atmosphere and passaged every 3/4 days.…”