Vitamin A pretreatment protects NO-induced bovine mammary epithelial cells from oxidative stress by modulating Nrf2 and NF-κB signaling pathways

Abstract

It is known that physiological overproduction of nitric oxide (NO) contributes to oxidative stress and inflammation. Our published studies indicated that vitamin A (VA) reduces NO-induced oxidative stress in bovine mammary epithelial cells (BMECs) by increasing antioxidant enzyme activities. However, the precise mechanism is unclear. The present study was conducted to examine the protective effects of VA on NO-induced damage to BMECs in vitro using diethylenetriamine nitric oxide (DETA-NO) as the NO donor and to explore the intracellular signaling mechanisms of VA that involve nuclear factor erythroid 2-related factor (Nrf2) and nuclear factor kappa-B (NF-κB). Subconfluent BMECs were divided into 10 treatment groups with 6 replicates per treatment and were cultured with dimethyl sulfoxide (DMSO, vehicle negative control) or 0, 0.05, 0.1, 0.2, 0.5, 1, 2, 3, or 4 μg/mL of VA for 24 h and then incubated in the absence or presence of DETA-NO (1,000 μmol/liter) and VA for an additional 6 h. The results showed that exposure to DETA alone decreased cell proliferation compared with the negative control. Pretreatment with VA promoted the proliferation of BMECs, increased the activities of antioxidative enzymes including selenoprotein glutathione peroxidase (GPx) and thioredoxin reductase (TrxR) and their gene and protein expression but decreased NO and interleukin 1 (IL-1) contents in a quadratic manner (P < 0.05). In addition, the expression of mRNA and protein of factors that are related to NF-κB or Nrf2 signaling pathways in BMECs were regulated by VA in a quadratic dose-dependent manner; VA at a concentration of 1 μg/mL exhibited the strongest effect. Together, these results suggest that VA promotes antioxidant functions of BMECs by regulating the synthesis of selenoproteins including GPx and TrxR and by reducing concentrations of IL-1 and NO in vitro by modulating Nrf2 and NF-κB signaling pathways.

Dandelion Extract Alleviated Lipopolysaccharide-Induced Oxidative Stress through the Nrf2 Pathway in Bovine Mammary Epithelial Cells

“…The Nrf2 pathway is stimulated by electrophiles and oxidants through the modification of critical cysteine thiols of Keap1 and/or phosphorylation of Nrf2, and the subsequently enhanced expression of antioxidant enzymes is achieved from the releasing of Nrf2 from Keap1 and translocating to the nucleus [ 31 ]. In the current study, protein expressions of both Nrf2 and Keap1 decreased after being treated with LPS, which was consistent with previous studies using different doses of pro-oxidants [ 7 , 20 , 32 ]. In contrast, the supplementation of DAE improved the expression of Nrf2 but declined expression of Keap1 at the DAE concentration of 50 μg/mL, which indicated that DAE induced the releasing of Nrf2 from Keap1.…”

Moringa Extract Attenuates Inflammatory Responses and Increases Gene Expression of Casein in Bovine Mammary Epithelial Cells

“…Previously, down-regulation of COX-2 by moringa extract was observed in other cell lines such as RAW 264.7 [41,42] and MCF-7 cells [43], in agreement with our data. Furthermore, the expression of COX-2 was regulated via NF-κB pathway in numerous studies using bovine mammary cells [3,20,24,44].…”

“…NF-κB is a heterodimer composed of p65 and p50 subunits [2,44]. Under normal circumstances, NF-κB heterodimer stays in the cytoplasm in an inactive form binding with an inhibitor of kappa-B alpha (IκBα).…”

Widespread basal cytochrome P450 expression in extrahepatic bovine tissues and isolated cells

“…Like CYP24A1, the induction of CYP26A1 is significantly reduced by LPS (Zolfaghari et al, 2007). Given the ability of AT-RA to protect bovine cells from oxidative stress and to potentiate the LPS-induced inflammatory cascade, preventing the induction of CYP26A1 may serve as a protective mechanism by prolonging the activity of AT-RA during infection (Shi et al, 2018;Xu et al, 2019).…”