Nicotinamide Ameliorates Deoxynivalenol-Induced Injury in Renal Cells via Inhibiting PARP1 Hyperactivation and Restoring NAD⁺ Homeostasis

Deoxynivalenol (DON) is a globally prevalent mycotoxin that threatens food and feed safety via severe multi-organ toxicity. Previous studies indicate that DON induces cellular energy metabolism dysregulation by triggering oxidative stress and impairing mitochondrial function. During this process, nicotinamide adenine dinucleotide (NAD⁺), a central coenzyme in cellular energy metabolism, frequently exhibits significantly decreased intracellular levels or even complete depletion. However, the molecular mechanisms underlying the disruption of NAD⁺ homeostasis by DON exposure, as well as the development of targeted countermeasures, remain elusive. Using human embryonic kidney 293T (HEK293T) cells as an in vitro renal toxicity model, we dissected DON-induced NAD⁺ dysregulation and evaluated the protective potential of nicotinamide (NAM). DON caused significant NAD⁺ depletion in porcine serum (in vivo) and HEK293T cells (in vitro), which was confirmed as a key driver of cytotoxicity. Mechanistically, although DON binds and inhibits nicotinamide phosphoribosyltransferase (NAMPT), the rate-limiting enzyme of the NAD⁺ salvage pathway, neither NAMPT knockdown and overexpression nor nicotinamide mononucleotide (NMN) supplementation rescued DON-induced toxicity. Instead, DON dose-dependently activated poly(ADP-ribose) polymerase 1 (PARP1), the primary intracellular NAD⁺-consuming enzyme, to accelerate NAD⁺ depletion. PARP1 knockdown markedly attenuated DON-induced cytotoxicity, identifying PARP1 hyperactivation as the core toxic mechanism. NAM dose-dependently suppressed PARP1 activity, replenished NAD⁺ pools, and reversed cell injury. These findings establish PARP1-driven NAD⁺ depletion as an important mechanism of DON-induced renal toxicity, providing a promising intervention candidate for mitigating DON toxicity in food safety.