BQ123 Stimulates Skeletal Muscle Antioxidant Defense via Nrf2 Activation in LPS-Treated Rats

Glycerol monolaurate improves intestinal morphology and antioxidant status by suppressing inflammatory responses and nuclear factor kappa-B signaling in lipopolysaccharide-exposed chicken embryos

Medium-chain fatty acids and their derivatives are natural ingredients that support immunological functions in animals. The effects of glycerol monolaurate (GML) on intestinal innate immunity and associated molecular mechanisms were investigated using a chicken embryo model. Sixty-four Arbor Acres broiler embryos were randomly allocated into four groups. On embryonic day 17.5, the broiler embryos were administered with 9 mg of GML, which was followed by a 12-h incubation period and a 12-h challenge with 32 μg of lipopolysaccharide (LPS). On embryonic day 18.5, the jejunum and ileum were harvested. Results indicated that GML reversed the LPS-induced decline in villus height and upregulated the expression of mucin 2 (P < 0.05). GML decreased LPS-induced malondialdehyde production and boosted antioxidant enzyme activity (P < 0.05). GML alleviated LPS-stimulated intestinal secretion of interleukin (IL)-1β, IL-6, and tumor necrosis factor-α (TNF-α) (P < 0.05). GML also normalized LPS-induced changes in the gene expression of Toll-like receptor 4, nuclear factor kappa-B p65 (NF-κB p65), cyclooxygenase-2, NOD-like receptor protein 3, IL-18, zonula occludens 1, and occludin (P < 0.05). GML enhanced as well the expression of AMP-activated protein kinase α1 and claudin 1 (P < 0.05). In conclusion, GML improved intestinal morphology and antioxidant status by alleviating inflammatory responses and modulating NF-κB signaling in LPS-challenged broiler embryos.

Antioxidant and Anti-inflammatory Effects of α-Lipoic Acid on Lipopolysaccharide-induced Oxidative Stress in Rat Kidney

α-Lipoic acid (α-LA) is a naturally occurring organosulfur component. Oxidative stress plays an essential role in the pathogenesis of various diseases, such as kidney and cardiovascular diseases, diabetes, neurodegenerative disorders, cancer and aging. Kidneys are especially vulnerable to oxidative stress and damage. The aim of the study was to evaluate the effect of α-LA on lipopolysaccharide (LPS)-induced oxidative stress parameters in rat kidneys. The experimental rats were divided into four groups: I-control (0.9% NaCl i.v.); II-α-LA (60 mg/kg b.w. i.v.); III-LPS (30 mg/kg b.w. i.v.); and IV-LPS + LA (30 mg/kg b.w. i.v. and 60 mg/kg b.w. i.v., respectively). In kidney homogenates the concentration of thiobarbituric acid reactive substances (TBARS), hydrogen peroxide (H₂O₂), sulfhydryl groups (-SH), total protein, superoxide dismutase (SOD), total glutathione (tGSH), reduced glutathione (GSH), glutathione disulphide (GSSG) and the GSH/GSSG ratio were determined. In addition, the levels of tumour necrosis factor (TNF)-α, and interleukin (IL)-6 were measured to assess inflammation and was estimated kidney oedema. Studies have shown that α-LA administered after LPS administration attenuated kidney oedema and significantly decreased TBARS, H₂O₂, TNF-α, and IL-6 levels in rat kidneys. α-LA also resulted in increase -SH group, total protein, and SOD levels and ameliorated the GSH redox status when compared to the LPS group. The results suggest that α-LA plays an important role against LPS-induced oxidative stress in kidney tissue as well as downregulating the expression of pro-inflammatory cytokines.

Attenuation of the degenerative effects of endothelin-1 on cartilaginous end plate cells by the endothelin receptor antagonist BQ-123 via the Wnt/β-catenin signaling pathway

BACKGROUND CONTEXT

Endothelin-1 (ET-1) is an inflammatory mediator associated with cartilage end plate (CEP) degeneration in the intervertebral disc (IVD). SOX9 is downregulated during CEP degeneration, along with its targets, collagen II and aggrecan. Wnt/β-catenin signaling is associated with CEP degeneration and a downstream target of SOX9; however, the precise mechanism of CEP degeneration and the role of ET-1 are largely unknown.

PURPOSE

The purpose of the study was to evaluate the influence of the endothelin-A receptor antagonist, BQ-123, on ET-1-induced effects on cartilaginous end plate cells (CECs) associated with CEP degeneration via the Wnt/β-catenin signaling pathway.

STUDY DESIGN/SETTING

The influence of ET-1 on the expression levels of collagen II, aggrecan, and SOX9 in CECs and the effect of BQ-123 in this context were investigated.

METHODS

To establish a model for CEP degeneration, three lumbar discs (L3-L4, L4-L5, and L5-L6 levels) in New Zealand white rabbits were punctured close to the vertebral end plate using a 14G needle. Intervertebral disc degeneration was evaluated by magnetic resonance imaging 4 weeks after vertebral end plate injury. CECs were then isolated from the degenerated CEPs to allow evaluation of the role of ET-1 and BQ-123 and to investigate their effects on the Wnt/β-catenin signaling pathway. The expression of ET-1 in CECs from degenerated CEPs was analyzed by immunofluorescent staining. Changes in the levels of collagen II, aggrecan, and SOX9 were evaluated in CECs by real-time polymerase chain reaction and by Western blotting. The Wnt/β-catenin signaling pathway was also investigated by Western blotting.

RESULTS

After 4 weeks, IVDs with vertebral end plate injury exhibited clear signs of disc degeneration. Immunofluorescent staining showed that ET-1 was expressed in the cytoplasm of CECs. Endothelin-1 stimulation significantly inhibited the expression of collagen II, aggrecan, and SOX9 in CECs, whereas BQ-123 increased the levels of these three molecules. In addition, ET-1 stimulation increased the expression of β-catenin, cyclin D1, and Dvl1 in the Wnt/β-catenin signaling pathway of CECs from degenerated discs and reduced the expression of GSK-3β, whereas BQ-123 had the opposite effect.

CONCLUSIONS

Endothelin-1 can reduce levels of collagen II, aggrecan, and SOX9 in CECs through activation of the Wnt/β-catenin signaling pathway, whereas BQ-123 attenuates these negative effects, highlighting a new molecular mechanism with potential for exploitation for treatment of CEP degeneration.