Bergenin alleviates H2 O2 -induced oxidative stress and apoptosis in nucleus pulposus cells: Involvement of the PPAR-γ/NF-κB pathway

Using network pharmacology and molecular docking to uncover the mechanism by which quercetin alleviates deoxynivalenol-induced porcine intestinal injury

Deoxynivalenol is a widespread feed contaminant that leads to vomit, which results in serious symptom such as increased intestinal permeability and even intestinal mucosal necrosis. Recent studies have reported the role of quercetin in alleviating deoxynivalenol-induced intestinal injury; however, the mechanisms and targets remain unclear. Thus, we aimed to identify the mechanisms of action by using a combination of network pharmacology and molecular docking. We identified 151 quercetin targets, 235 deoxynivalenol targets and 47 porcine intestinal injury targets by searching compound database and PubMed database, among which there were two common targets. The PPI network showed that the key proteins involved are NQO1 and PPAR-γ. The PPI network showed that the key proteins involved were NQO1 and PPARG. GO analysis found that genes were enriched primarily in response to oxidative stress. The PPI network showed that the key proteins involved are NQO1 and PPAR-γ. The genes are enriched primarily in response to oxidative stress. KEGG analysis showed enrichment of the HIF, reactive oxygen species and other signaling pathways. The molecular docking results indicated key binding activity between NQO1-quercetin and PPAR-γ-quercetin. By using network pharmacology, we have revealed the potential molecular mechanisms by which quercetin alleviates deoxynivalenol-induced porcine intestinal injury, which lays the foundation for the development of drugs to treat deoxynivalenol-induced intestinal injury in pigs.

DNMT3a-mediated methylation of PPARγ promote intervertebral disc degeneration by regulating the NF-κB pathway

Intervertebral disc degeneration (IVDD) is a common chronic musculoskeletal disease that causes chronic low back pain and imposes an immense financial strain on patients. The pathological mechanisms underlying IVDD have not been fully elucidated. The development of IVDD is closely associated with abnormal epigenetic changes, suggesting that IVDD progression may be controlled by epigenetic mechanisms. Consequently, this study aimed to investigate the role of epigenetic regulation, including DNA methyltransferase 3a (DNMT3a)-mediated methylation and peroxisome proliferator-activated receptor γ (PPARγ) inhibition, in IVDD development. The expression of DNMT3a and PPARγ in early and late IVDD of nucleus pulposus (NP) tissues was detected using immunohistochemistry and western blotting analyses. Cellularly, DNMT3a inhibition significantly inhibited IL-1β-induced apoptosis and extracellular matrix (ECM) degradation in rat NP cells. Pretreatment with T0070907, a specific inhibitor of PPARγ, significantly reversed the anti-apoptotic and ECM degradation effects of DNMT3a inhibition. Mechanistically, DNMT3a modified PPARγ promoter hypermethylation to activate the nuclear factor-κB (NF-κB) pathway. DNMT3a inhibition alleviated IVDD progression. Conclusively, the results of this study show that DNMT3a activates the NF-κB pathway by modifying PPARγ promoter hypermethylation to promote apoptosis and ECM degradation. Therefore, we believe that the ability of DNMT3a to mediate the PPARγ/NF-κB axis may provide new ideas for the potential pathogenesis of IVDD and may become an attractive target for the treatment of IVDD.

Bergenin alleviates Diabetic Retinopathy in STZ-induced rats

Diabetic retinopathy (DR) is the key cause of blindness and visual impairment in diabetes patients around the world. The high levels of oxidative stress in diabetes patients cause diabetic retinopathy. In addition to being an antioxidant, Bergenin also works as an immunosuppressant, an anti-inflammatory, and anticarcinogenic against hepatocarcinoma. This study examined the effects of Bergenin on diabetic retinopathy rats, using Streptozotocin (STZ) intraperitoneally to induce diabetes in rats. The animals were divided into four groups (n = 6), including a normal control (Group I), diabetic control (Group II), Bergenin (25 mg/kg) (Group III), and metformin (350 mg/kg) (Group IV). As previously mentioned, each animal received treatment for 60 days. To induce DR, rats were administered STZ (60 mg/kg) intraperitoneally for 60 days. Standard methods were utilized to measure the body weight of rats, blood glucose levels. We measured lipid profiles (Triglycerides, cholesterol, LDL, and HDL), inflammatory markers, and antioxidant levels with their respective kits. Analysis of retinal tissue morphometry and MMP-9, VEGF, and MCP-1 levels in serum was performed. Our research examined the expression levels of target genes (TNF-α, IL-1β, and IL-6) using RT-PCR analysis. STZ-induced animals that were treated with Bergenin had less food intake, lower blood glucose, and improved body weight. Bergenin significantly suppressed levels of pro-inflammatory cytokines, cholesterol, TG, LDL, AI, MMP-9, VEGF, and MCP-1 and increased the level of HDL and antioxidant enzymes in STZ-induced DR rats. As well as increasing antioxidant levels, reducing retinal thickness, and increasing cell numbers, Bergenin also lessened DR remarkably. The results of this study demonstrated that Bergenin effectively inhibited STZ-induced DR in rats.

Silica nanoparticles promoted pro-inflammatory macrophage and foam cell transformation via ROS/PPARγ/NF-κB signaling

Experimental evidence has pointed out silica nanoparticles (SiNPs) possessing a proatherogenic capability. However, the interplay between SiNPs and macrophages in the pathogenesis of atherosclerosis was poorly understood. Here, we demonstrated SiNPs could promote macrophage adhesion to endothelial cells, accompanied by elevated Vcam1 and Mcp1. Upon SiNPs stimuli, macrophages manifested enhanced phagocytic activity and a pro-inflammatory phenotype, as reflected by the transcriptional determination of M1/M2-related biomarkers. In particular, our data certified the increased macrophage M1 subset facilitated more lipid accumulation and resultant foam cell transformation in comparison to the M2 phenotype. More importantly, the mechanistic investigations revealed ROS-mediated PPARγ/NF-κB signaling was a key contributor to the above phenomena. That was, SiNPs caused ROS accumulation in macrophages, resulting in the deactivation of PPARγ, nuclear translocation of NF-κB, ultimately contributing to macrophage phenotype shift toward M1 and foam cell transformation. Collectively, we first revealed SiNPs facilitated pro-inflammatory macrophage and foam cell transformation via ROS/PPARγ/NF-κB signaling. These data would provide new insight into the atherogenic property of SiNPs in a macrophage model.

Protective effect of C-phycocyanin and apo-phycocyanin subunit on programmed necrosis of GC-1 spg cells induced by H2 O2

C-phycocyanin (C-PC) is an effective antioxidant and has an important value in medical research. Oxidative stress is considered to be one of the main underlying mechanisms of cell death, and reducing oxidative stress is one of the strategies to enhance germ cell viability. Herein, we investigated the protective effect and the mechanism of C-PC and apo-phycocyanin subunit on oxidative stress damage induced by H₂ O₂ in GC-1 spg cells. C-PC genes were cloned into the pGEX-4T-1 vectorand transformed into Escherichia coli BL21 to achieve the efficient expression of C-PC subunit. GC-1 spg cells were treated with 600 μM H₂ O₂ for 24 h to establish the oxidative stress damage model. Cell viability was detected by CCK-8. The degree of oxidative stress was detected by testing Superoxide dismutase (SOD) and glutathione peroxidase (GPx) activities and glutathione (GSH) and Malondialdehyde (MDA) levels. Reactive oxygen species (ROS) was evaluated utilizingby 2', 7'-dichlorofluorescent-diacetate (DCFH-DA). Mitochondrial membrane potential was determined by JC-1. Cell necrosis rate was detected by Annexin V-FITC/PI. Expression of protein was detected by western blot. We found that C-PC and GST-CPC β significantly inhibited H₂ O₂ -induced oxidative damage of GC-1 spg cells, improved the ability of antioxidation, reduced ROS overproduction, and mitochondrial membrane potential loss, and inhibited the RIP-1/RIP-3/ p-MLKL signaling pathway to reduce the necrosis rate. The results demonstrated that C-PC played a protective role against H₂ O₂ -induced cell damage, especially its β subunit. This study provides a theoretical basis for C-PC as a potential protective agent of reproductive system.

Peroxisome Proliferator-Activated Receptors (PPARs) and Oxidative Stress in Physiological Conditions and in Cancer

Peroxisome proliferator-activated receptors (PPARs) belong to the nuclear hormone receptor superfamily. Originally described as “orphan nuclear receptors”, they can bind both natural and synthetic ligands acting as agonists or antagonists. In humans three subtypes, PPARα, β/δ, γ, are encoded by different genes, show tissue-specific expression patterns, and contribute to the regulation of lipid and carbohydrate metabolisms, of different cell functions, including proliferation, death, differentiation, and of processes, as inflammation, angiogenesis, immune response. The PPAR ability in increasing the expression of various antioxidant genes and decreasing the synthesis of pro-inflammatory mediators, makes them be considered among the most important regulators of the cellular response to oxidative stress conditions. Based on the multiplicity of physiological effects, PPAR involvement in cancer development and progression has attracted great scientific interest with the aim to describe changes occurring in their expression in cancer cells, and to investigate the correlation with some characteristics of cancer phenotype, including increased proliferation, decreased susceptibility to apoptosis, malignancy degree and onset of resistance to anticancer drugs. This review focuses on mechanisms underlying the antioxidant and anti-inflammatory properties of PPARs in physiological conditions, and on the reported beneficial effects of PPAR activation in cancer.