| Autor: |
Zhai Y; CVMR-PH Discovery, Johnson & Johnson Innovative Medicine Research & Development, Spring House, Pennsylvania, United States., Chavez JA; CVMR-PH Discovery, Johnson & Johnson Innovative Medicine Research & Development, Spring House, Pennsylvania, United States., D'Aquino KE; CVMR-PH Discovery, Johnson & Johnson Innovative Medicine Research & Development, Spring House, Pennsylvania, United States., Meng R; CVMR-PH Discovery, Johnson & Johnson Innovative Medicine Research & Development, Spring House, Pennsylvania, United States., Nawrocki AR; CVMR-PH Discovery, Johnson & Johnson Innovative Medicine Research & Development, Spring House, Pennsylvania, United States., Pocai A; CVMR-PH Discovery, Johnson & Johnson Innovative Medicine Research & Development, Spring House, Pennsylvania, United States., Wang L; CVMR-PH Discovery, Johnson & Johnson Innovative Medicine Research & Development, Spring House, Pennsylvania, United States., Ma LJ; CVMR-PH Discovery, Johnson & Johnson Innovative Medicine Research & Development, Spring House, Pennsylvania, United States. |
| Abstrakt: |
Nicotinamide adenine dinucleotide (NAD + ) is a pivotal coenzyme, essential for cellular reactions, metabolism, and mitochondrial function. Depletion of kidney NAD + levels and reduced de novo NAD + synthesis through the tryptophan-kynurenine pathway are linked to acute kidney injury (AKI), whereas augmenting NAD + shows promise in reducing AKI. We investigated de novo NAD + biosynthesis using in vitro, ex vivo, and in vivo models to understand its role in AKI. Two-dimensional (2-D) cultures of human primary renal proximal tubule epithelial cells (RPTECs) and HK-2 cells showed limited de novo NAD + synthesis, likely due to low pathway enzyme gene expression. Using three-dimensional (3-D) spheroid culture model improved the expression of tubular-specific markers and enzymes involved in de novo NAD + synthesis. However, de novo NAD + synthesis remained elusive in the 3-D spheroid culture, regardless of injury conditions. Further investigation revealed that 3-D cultured cells could not metabolize tryptophan (Trp) beyond kynurenine (KYN). Intriguingly, supplementation of 3-hydroxyanthranilic acid into RPTEC spheroids was readily incorporated into NAD + . In a human precision-cut kidney slice (PCKS) ex vivo model, de novo NAD + synthesis was limited due to substantially downregulated kynurenine 3-monooxygenase (KMO), which is responsible for KYN to 3-hydroxykynurenine conversion. KMO overexpression in RPTEC 3-D spheroids successfully reinstated de novo NAD + synthesis from Trp. In addition, in vivo study demonstrated that de novo NAD + synthesis is intact in the kidney of the healthy adult mice. Our findings highlight disrupted tryptophan-kynurenine NAD + synthesis in in vitro cellular models and an ex vivo kidney model, primarily attributed to KMO downregulation. NEW & NOTEWORTHY Nicotinamide adenine dinucleotide (NAD + ) is essential in regulating mitochondrial function. Reduced NAD + synthesis through the de novo pathway is associated with acute kidney injury (AKI). Our study reveals a disruption in de novo NAD + synthesis in proximal tubular models, but not in vivo, attributed to downregulation of enzyme kynurenine 3-monooxygenase (KMO). These findings highlight a crucial role of KMO in governing de novo NAD + biosynthesis within the kidney, shedding light on potential AKI interventions. |
