Dextran sodium sulfate (DSS)-induced colitis is alleviated in mice after administration of flavone-derived NRF2-activating molecules

Inflammatory Bowel Disease (IBD) is a chronic and relapsing inflammatory condition characterized by severe symptoms such as diarrhea, fatigue, and weight loss. Growing evidence underscores the direct involvement of the nuclear factor-erythroid 2-related factor 2 (NRF2) in the development and progression of IBD, along with its associated complications, including colorectal cancer. The NRF2 pathway plays a crucial role in cellular responses to oxidative stress, and dysregulation of this pathway has been implicated in IBD. Flavones, a significant subclass of flavonoids, have shown pharmacological impacts in various diseases including IBD, through the NRF2 signaling pathway. In this study, we conducted a screening of compounds with a flavone structure and identified NJK15003 as a promising NRF2 activator. NJK15003 demonstrated potent NRF2 activation, as evidenced by the upregulation of downstream proteins, promoter activation, and NRF2 nuclear translocation in IBD cellular models. Treatment with NJK15003 effectively restored the protein levels of tight junctions in cells treated with dextran sodium sulfate (DSS) and in DSS-treated mice, suggesting its potential to protect cells from barrier integrity disruption in IBD. In DSS-treated mice, the administration of NJK15003 resulted in the prevention of body weight loss, a reduction in colon length shortening, and a decrease in the disease activity index. Furthermore, NJK15003 treatment substantially alleviated inflammatory responses and apoptotic cell death in the colon of DSS-treated mice. Taken together, this study proposes the potential utility of NRF2-activating flavone compounds, exemplified by NJK15003, for the treatment of IBD.

α-Pyrrolidinononanophenone derivatives induce differentiated SH-SY5Y neuroblastoma cell apoptosis via reduction of antioxidant capacity: Involvement of NO depletion and inactivation of Nrf2/HO1 signaling pathway

α-Pyrrolidinononanophenone (α-PNP) derivatives are known to be one of the hazardous new psychoactive substances due to the most extended hydrocarbon chains of any pyrrolidinophenones on the illicit drug market. Our previous report showed that 4'-iodo-α-PNP (I-α-PNP) is the most potent cytotoxic compound among α-PNP derivatives and induces apoptosis due to mitochondrial dysfunction and suppression of nitric oxide (NO) production in differentiated human neuronal SH-SY5Y cells. In this study, to clarify the detailed action mechanisms by I-α-PNP, we investigated the mechanism of reactive oxygen species (ROS) -dependent apoptosis by I-α-PNP in differentiated SH-SY5Y with a focus on the antioxidant activities. Treatment with I-α-PNP elicits overproduction of ROS such as H2O2, hydroxyl radical, and 4-hydroxy-2-nonenal, and pretreatment with antioxidant N-acetyl-L-cysteine is attenuated the SH-SY5Y cells apoptosis by I-α-PNP. These results suggested that the overproduction of ROS is related to SH-SY5Y cell apoptosis by I-α-PNP. In addition, I-α-PNP markedly decreased antioxidant capacity in differentiated cells than in undifferentiated cells and inhibited the upregulation of hemeoxygenase 1 (HO1) and glutathione peroxidase 4 (GPX4) expression caused by induction of differentiation. Furthermore, the treatment with I-α-PNP increased the nuclear expression level of BTB Domain And CNC Homolog 1 (Bach1), a transcriptional repressor of Nrf2, only in differentiated cells, suggesting that the marked decrease in antioxidant capacity in differentiated cells was due to suppression of Nrf2/HO1 signaling by Bach1. Additionally, pretreatment with an NO donor suppresses the I-α-PNP-evoked ROS overproduction, HO1 down-regulation, increased nuclear Bach1 expression and reduced antioxidant activity in the differentiated cells. These findings suggest that the ROS-dependent apoptosis by I-α-PNP in differentiated cells is attributed to the inactivation of the Nrf2/HO1 signaling pathway triggered by NO depletion.

Study on the Correlation Between Regulatory Proteins of N6-methyladenosine and Oxidative Damage in Cadmium-induced Renal Injury

As a common environmental heavy metal pollutant, cadmium has been well evidenced to cause kidney damage; yet, the underlying mechanisms are still not fully clarified. In this study, cell viability of human renal tubular epithelial cell (HK-2) was determined by CCK-8 assay after treatment with CdSO₄. Then, apoptotic morphology of cells was observed by Hoechst staining and level of reactive oxygen species (ROS) was detected by fluorescent probes. Subsequently, mRNA levels of Nrf2, HO-1, m⁶A methyltransferases (METTL3, METTL14, METTL16, WATP), m⁶A demethylases (FTO, ALKBH5), m⁶A methyl-binding proteins (YTHDF1, YTHDF2, YTHDF3, YTHDC1, YTHDC2) were detected by real-time polymerase chain reaction (RT-PCR), closely followed by correlation analysis between Nrf2 mRNA levels and m⁶A methyltransferases and demethylases. Lastly, protein expressions of Nrf2, METTL3, and FTO were tested by western blotting assay. The detection results demonstrated that the treatment of CdSO₄ decreased viability while increased apoptosis rate. The Nrf2 mRNA level in CdSO₄-treated cells was significantly increased when compared with that in the control cells, and the HO-1 mRNA level elevated with the increasing of CdSO₄ concentrations. In addition, mRNA levels of METTL3, METTL14, METTL16, WTAP, FTO, and methyl-binding proteins in CdSO₄-treated cells were all higher than those in corresponding control cells. Further determination showed that protein expressions of Nrf2, METTL3, and FTO were also upregulation under the treatment of CdSO₄. Lastly, correlation analysis indicated that mRNA level of Nrf2 was positively correlated with mRNA levels of m⁶A methyltransferases and demethylases. In a word, our results demonstrated that the molecular changes of Nrf2 signaling pathway are correlated with the levels of m⁶A regulatory proteins, suggesting that there may be a regulatory relationship between Nrf2 signaling pathway and m⁶A regulatory proteins in the process of cadmium-induced renal cell cytotoxicity.

Nrf2 regulates the activation of THP-1 cells induced by chloral hydrate

Trichloroethylene (TCE) triggers a severe hypersensitivity syndrome in the occupational population dependent on dendritic cells (DCs). Chloral hydrate (CH), the major oxidative metabolite of TCE, has been proved to be the culprit causative substance of TCE-induced hypersensitivity by human patch tests. Because redox imbalance is essential for chemical sensitizers-induced maturation of DCs, we predicted that CH would activate DCs by the nuclear factor E2-related factor 2 (Nrf2)-mediated antioxidant response. This study selected THP-1 cells as the in vitro DC model, and we evaluated the cell activation markers, intracellular oxidative stress, and Nrf2 pathway related genes expression in response to CH in THP-1 cells. CH displayed significant stimulation of THP-1 cells activation, including CD54 and CD86 expression, IL-8 release, and cell migration, and damaged the redox balance by triggering ROS generation, GSH consumption, and antioxidase activities modulation. The levels of Nrf2 and its downstream genes (HO-1 and NQO1) in mRNA and protein expressions were upregulated by CH, and CH also promoted the nuclear translocation of Nrf2. Subsequently, we investigated the effects of antioxidant on Nrf2-mediated cell defense in CH treated cells. Pretreatment with curcumin dramatically reduced cell activation and oxidative stress triggered by CH in THP-1 cells. We also confirmed the specific role of Nrf2 in CH-induced cell activation using NRF2-knockout cells. Deficiency of Nrf2 inhibited cell activation and downregulated HO-1 and NQO1 expression in CH-challenged cells. These findings suggest that Nrf2-dependent redox homeostasis plays a pivotal role in CH-induced activation of THP-1 cells, thereby providing new knowledge of the allergen as well as the molecular mechanism involving in TCE-induce hypersensitivity syndrome.

Panax quinquefolius saponin inhibits vascular smooth muscle cell calcification via activation of nuclear factor-erythroid 2-related factor 2

BACKGROUND

Panax quinquefolius saponin (PQS) is the main active component of Panax quinquefolius. Emerging evidence suggests that PQS exerts beneficial effects against cardiovascular diseases. However, the role and mechanism of PQS in vascular calcification are not unclear. The present study investigated the effects of PQS on the calcification of vascular smooth muscle cell (VSMCs).

METHODS

The present study used calcification medium containing 3 mM inorganic phosphate (Pi) to induce rat VSMCs calcification. We investigated the effects of PQS on VSMCs calcification using alizarin red staining and alkaline phosphatase (ALP) activity assays. The intracellular reactive oxygen species (ROS) levels and the transcriptional activity of nuclear factor-erythroid 2-related factor 2 (Nrf2) were determined. The mRNA and protein expression levels of Nrf2, the antioxidant gene heme oxygenase-1 (HO-1), osteogenic markers, including runt-related transcription factor 2 (Runx2) and bone morphogenetic protein 2 (BMP2), and Kelch-like ECH-associated protein 1 (Keap1) were also measured.

RESULTS

Treatment with Pi significantly increased intracellular calcium deposition and ALP activity, which were suppressed by PQS in a concentration-dependent manner. During VSMCs calcification, PQS inhibited the mRNA and protein expression of Runx2 and BMP2. PQS treatment reduced intracellular ROS production and significantly upregulated Nrf2 transcriptional activity and the expression of Nrf2 and its target antioxidant gene HO-1. PQS suppressed the Pi-induced protein expression of Keap1, which is an endogenous inhibitor of Nrf2. Keap1 siRNA treatment induced Nrf2 expression and downregulated Runx2 expression in the presence of Pi and PQS.

CONCLUSION

Taken together, these findings suggest that PQS could effectively inhibit VSMCs calcification by ameliorating oxidative stress and regulating osteogenic genes via the promotion of Nrf2 expression.

[Expression of LIAS and NRF2 in PBMCs from patients with silicosis and their correlation with silicosis]

Objective: To investigate the expression of lipoic acid synthase gene (LIAS) and nuclear factor-erythroid 2-related factor 2 gene (NRF2) in peripheral blood mononuclear cells (PBMCs) from patients with silicosis and their correlation with silicosis. Methods: A total of 45 healthy controls and 107 patients with silicosis were randomly selected in this study in May 2019. PBMCs were isolated from peripheral blood and NRF2 protein expression was detected by immunofluorescence. The mRNA levels of LIAS and NRF2 in PBMCs were determined by real-time PCR. The dose-response relationship beween LIAS and NRF2 mRNA expression levels and their association with silicosis were analyzed by restricted cubic spline (RCS) and logistic regression. Results: Compared with the control group, the number of monocytes in the case group was significantly increased, and the forced expiratory volume in the first second (FEV(1.0)) decreased, the difference was statistically significant (P<0.05) . The positive expression rate of NRF2 in PBMCs of silicosis patients in stage Ⅰ group was significantly higher than that in the control group, and the positive expression rate of NRF2 in silicosis patients in stageⅡ and Ⅲ groups was lower than that in silicosis patients in control group and stage Ⅰ group (P<0.01) . Results of RCS showed that there was a linear dose-response relationship between LIAS and NRF2 mRNA expression (overall correlation test, χ(2)=213.710, P<0.01; non-linear test, χ(2)=1.340, P=0.511) . There was a positive correlation between mRNA expression of LIAS and that of NRF2 (r=0.651, P<0.01) . The results of multivariate analysis showed that LIAS and NRF2 were increased the risk of incidence in silicosis patients with stageⅠ (OR=11.184, 4.332, P<0.05) and NRF2 was the protective factor in silicosis patients with stage Ⅱ and Ⅲ (OR=0.225, 0.208, P<0.05) after adjusting for potential confounding factors including age, education level, BMI and smoking. Conclusion: There is a linear dose-response relationship between the expression of LIAS and NRF2 mRNA in PBMCs of silicosis patients, LIAS and NRF2 are involved in the pathogenesis of silicosis.

Genome-wide mRNA profiling identifies the NRF2-regulated lymphocyte oxidative stress status in patients with silicosis

BACKGROUND

The immunomodulatory abnormalities of silicosis are related to the lymphocyte oxidative stress state. The potential effect of antioxidant therapy on silicosis may depend on the variation in nuclear factor erythroid 2-related factor 2 (NRF2)-regulated antioxidant genes in peripheral blood mononuclear cells (PBMCs). As NRF2 is a redox-sensitive transcription factor, its possible roles and underlying mechanism in the treatment of silicosis need to be clarified.

METHODS

Ninety-two male patients with silicosis and 87 male healthy volunteers were randomly selected. PBMCs were isolated from fresh blood from patients with silicosis and healthy controls. The lymphocyte oxidative stress state was investigated by evaluating NRF2 expression and NRF2-dependent antioxidative genes in PBMCs from patients with silicosis. Key differentially expressed genes (DEGs) and signaling pathways were identified utilizing RNA sequencing (RNA-Seq) and bioinformatics technology. Gene set enrichment analysis was used to identify the differences in NRF2 signaling networks between patients with silicosis and healthy controls.

RESULTS

The number of monocytes was significantly higher in patients with silicosis than that of healthy controls. Furthermore, RNA-Seq findings were confirmed using quantitative polymerase chain reaction and revealed that NRF2-regulated DEGs were associated with glutathione metabolism, transforming growth factor-β, and the extracellular matrix receptor interaction signaling pathway in PBMCs from patients with silicosis. The top 10 hub genes were identified by PPI analysis: SMAD2, MAPK3, THBS1, SMAD3, ITGB3, integrin alpha-V (ITGAV), von Willebrand factor (VWF), BMP4, CD44, and SMAD7.

CONCLUSIONS

These findings suggest that NRF2 signaling regulates the lymphocyte oxidative stress state and may contribute to fibrogenic responses in human PBMCs. Therefore, NRF2 might serve as a novel preventive and therapeutic candidate for silicosis.

Jian-Pi-Yi-Shen Formula Ameliorates Oxidative Stress, Inflammation, and Apoptosis by Activating the Nrf2 Signaling in 5/6 Nephrectomized Rats

Chronic kidney disease (CKD) is an increasing global public health problem, with high morbidity and mortality. Jian-Pi-Yi-Shen (JPYS) formula is a representative traditional Chinese medicine formula in the treatment of CKD, which is widely used in clinical practice in China. However, the underlying mechanism has not been well elucidated. In the present study, we measured the markers of apoptosis, inflammation, oxidative stress, and nuclear factor erythroid 2–related factor 2 (Nrf2) signaling to investigate the effects of JPYS formula on renal function and fibrosis and its molecular mechanism in an established animal model of 5/6 nephrectomized (5/6Nx) rats. The results demonstrated that the JPYS formula exerted a significant preventive effect on renal dysfunction and fibrosis, based on analysis of correlative parameters such as urinary protein, SCr, BUN, glomerular sclerosis index, and tubulointerstitial fibrosis score and renal histopathology and ultrastructural pathology of CKD rats. JPYS formula also induced downregulation of gene expression associated with fibrosis, such as TGF-β and type I, III, and IV collagen. Moreover, the JPYS formula showed a significant protective effect in suppressing cell apoptosis according to the results of apoptotic indexes, including increased gene expression of Bcl-2, decreased gene expression of Bax, caspase 3, caspase 9, and the number of TUNEL-positive cells. JPYS formula also ameliorated the activation of the NF-κB-mediated inflammatory pathway, as manifested by the downregulation of gene expression of TNF-α, IL-1β, IκBα, NF-κB p65, MCP-1, CXCL1, COX-2, and iNOS in the kidney. Our evidence also suggested that the JPYS formula ameliorates oxidative stress by promoting antioxidant function according to antioxidant index indicators as an indicator of GSH, SOD, CAT, and GPx and abating excessive accumulation of the reactive oxygen species biomarkers, including ROS, TBARS, 8-oxo-dG, and MDA. The data also suggested that the JPYS formula reversed the downregulation of HO-1 and Nrf2 level and upregulation of Keap1 expression. Together, our data highlighted that the JPYS formula relieved renal oxidative injury mediated by activation of Nrf2 signaling by inhibiting inflammation and apoptosis in CKD rats.

Weight-loss-independent benefits of exercise on liver steatosis and stiffness in Japanese men with NAFLD

Background & Aims

A weight-loss-independent beneficial effect of exercise on non-alcoholic fatty liver disease (NAFLD) management has been reported, but the underlying mechanism is unknown. To help determine this mechanism, the effects of exercise on individual tissues (liver, adipose tissue, and skeletal muscle) were retrospectively studied.

Methods

Data from Japanese obese men with NAFLD in a 3-month exercise regimen were analysed and compared with those in a 3-month dietary restriction program designed to achieve weight loss. The underlying mechanism was studied in a smaller subcohort.

Results

Independent of the effect of weight loss, the exercise regimen reduced liver steatosis by 9.5% and liver stiffness by 6.8% per 1% weight loss, and resulted in a 16.4% reduction in FibroScan-AST score. Improvements in these hepatic parameters were closely associated with anthropometric changes (reduction in adipose tissue and preservation of muscle mass), increases in muscle strength (+11.6%), reductions in inflammation and oxidative stress (ferritin: -22.3% and thiobarbituric acid: -12.3%), and changes in organokine concentrations (selenoprotein-P: -11.2%, follistatin: +17.1%, adiponectin: +8.9%, and myostatin: -21.6%) during the exercise regimen. Moreover, the expression of target genes of the transcription factor Nrf2, an oxidative stress sensor, was higher in monocytes, suggesting that Nrf2 is activated. Large amounts of high-intensity exercise were effective at further reducing liver steatosis and potentiating improvements in pathophysiological parameters (liver enzyme activities and organokine profiles).

Conclusions

The weight-loss-independent benefits of exercise include anti-steatotic and anti-stiffness effects in the livers of patients with NAFLD. These benefits seem to be acquired through the modification of inter-organ crosstalk, which is characterised by improvements in organokine imbalance and reductions in inflammation and oxidative stress.

Lay summary

We investigated the effects of exercise on non-alcoholic fatty liver disease (NAFLD) that were not related to weight loss. We found that exercise had considerable weight-loss-independent benefits for the liver through a number of mechanisms. This suggests that exercise is important for NAFLD patients, regardless of whether they lose weight.

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Exercise has effects on liver steatosis and stiffness, independent of weight loss.

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Exercise maintains muscle mass and alters the secretion of organokines.

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Exercise increases the phagocytic capacity of Kupffer cells and activates Nrf2.

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Exercise, especially vigorous exercise, should be used aggressively to manage non-alcoholic fatty liver disease (NAFLD).

The protective effects of fibroblast growth factor 10 against hepatic ischemia-reperfusion injury in mice

Hepatic ischemia-reperfusion injury (IRI) is a major complication of liver surgery and transplantation. IRI leads to hepatic parenchymal cell death, resulting in liver failure, and lacks effective therapeutic approaches. Fibroblast growth factor 10 (FGF10) is a paracrine factor which is well-characterized with respect to its pro-proliferative effects during embryonic liver development and liver regeneration, but its role in hepatic IRI remains unknown. In this study, we investigated the role of FGF10 in liver IRI and identified signaling pathways regulated by FGF10. In a mouse model of warm liver IRI, FGF10 was highly expressed during the reperfusion phase. In vitro experiments demonstrated that FGF10 was primarily secreted by hepatic stellate cells and acted on hepatocytes. The role of FGF10 in liver IRI was further examined using adeno-associated virus-mediated gene silencing and overexpression. Overexpression of FGF10 alleviated liver dysfunction, reduced necrosis and inflammation, and protected hepatocytes from apoptosis in the early acute injury phase of IRI. Furthermore, in the late phase of IRI, FGF10 overexpression also promoted hepatocyte proliferation. Meanwhile, gene silencing of FGF10 had the opposite effect. Further studies revealed that overexpression of FGF10 activated nuclear factor-erythroid 2-related factor 2 (NRF2) and decreased oxidative stress, mainly through activation of the phosphatidylinositol-3-kinase/AKT pathway, and the protective effects of FGF10 overexpression were largely abrogated in NRF2 knockout mice. These results demonstrate the protective effects of FGF10 in liver IRI, and reveal the important role of NRF2 in FGF10-mediated hepatic protection during IRI.

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FGF10 is markedly upregulated in the early phase of liver IRI.

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FGF10 overexpression exerts great potential in ameliorating hepatic IRI.

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FGF10 knockdown significantly aggravates hepatic IRI.

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FGF10 overexpression activates PI3K/AKT-NRF2 signaling and thus ameliorates hepatic IRI.

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NRF2 knockout abrogates the protective effects of FGF10 overexpression during liver IRI.

Genetic polymorphisms of MAFK, encoding a small Maf protein, are associated with susceptibility to ulcerative colitis in Japan

AIM

To investigate whether single nucleotide polymorphisms in maf protein K (MAFK), which encodes the MAFK, lead to increased susceptibility to ulcerative colitis in the Japanese population.

METHODS

This case control study examined the associations between MAFK single nucleotide polymorphisms (rs4268033 G>A, rs3735656 T>C and rs10226620 C>T) and ulcerative colitis susceptibility in 174 patients with ulcerative colitis (UC) cases, and 748 subjects without no lower abdominal symptoms, diarrhea or hematochezia (controls). In addition, as the second controls, we set 360 subjects, who have an irregular bowel movement without abnormal lower endoscopic findings (IBM controls).

RESULTS

The genotype frequency of rs4268033 AA and allelic frequency of the rs4268033A allele were significantly higher in the UC cases than in both controls (P = 0.0005 and < 0.0001, P = 0.015 and 0.0027 vs controls and IBM controls, respectively). Logistic regression analysis after adjustment for age and gender showed that the rs4268033 AA and rs3735656 CC genotypes were significantly associated with susceptibility to UC development (OR = 2.63, 95%CI: 1.61-4.30, P = 0.0001 and OR = 1.81; 95%CI: 1.12-2.94, P = 0.015, respectively). Similar findings were observed by the comparison with IBM controls. In addition, the rs4268033 AA genotype was significantly associated with all phenotypes of UC except early onset. There was no significant association between rs10226620 and ulcerative colitis.

CONCLUSION

Our results provide the first evidence that MAFK genetic polymorphisms are significantly associated with susceptibility to UC development. In particular, rs4268033 is closely associated with an increased risk for the development of UC.

Melatonin Stimulates the SIRT1/Nrf2 Signaling Pathway Counteracting Lipopolysaccharide (LPS)-Induced Oxidative Stress to Rescue Postnatal Rat Brain

AIMS

Lipopolysaccharide (LPS) induces oxidative stress and neuroinflammation both in vivo and in vitro. Here, we provided the first detailed description of the mechanism of melatonin neuroprotection against LPS-induced oxidative stress, acute neuroinflammation, and neurodegeneration in the hippocampal dentate gyrus (DG) region of the postnatal day 7 (PND7) rat brain.

METHODS

The neuroprotective effects of melatonin against LPS-induced neurotoxicity were analyzed using multiple research techniques, including Western blotting, immunofluorescence, and enzyme-linked immunosorbent assays (ELISAs) in PND7 rat brain homogenates and BV2 cell lysates in vitro. We also used EX527 to inhibit silent information regulator transcript-1 (SIRT1).

RESULTS

A single intraperitoneal (i.p) injection of LPS to PND7 rats significantly induced glial cell activation, acute neuroinflammation, reactive oxygen species (ROS) production and apoptotic neurodegeneration in hippocampal DG region after 4 h. However, the coadministration of melatonin significantly inhibited both LPS-induced acute neuroinflammation and apoptotic neurodegeneration and improved synaptic dysfunction in the hippocampal DG region of PND7 rats. Most importantly, melatonin stimulated the SIRT1/Nrf2 (nuclear factor-erythroid 2-related factor 2) signaling pathway to reduce LPS-induced ROS generation. The beneficial effects of melatonin were further confirmed in LPS-stimulated BV2 microglia cell lines in vitro using EX527 as an inhibitor of SIRT1. LPS-induced oxidative stress, Nrf2 inhibition, and neuroinflammation are SIRT1-dependent in BV2 microglia cell lines.

CONCLUSION

These results demonstrated that melatonin treatment rescued the hippocampal DG region of PND7 rat brains against LPS-induced oxidative stress damage, acute neuroinflammation, and apoptotic neurodegeneration via SIRT1/Nrf2 signaling pathway activation.

Antagonistic effects of acetylshikonin on LPS-induced NO and PGE2 production in BV2 microglial cells via inhibition of ROS/PI3K/Akt-mediated NF-κB signaling and activation of Nrf2-dependent HO-1

Although acetylshikonin (ACS) is known to have antioxidant and antitumor activities, whether ACS regulates the expression of proinflammatory mediators in lipopolysaccharide (LPS)-stimulated microglial cells remains unclear. In this study, it was found that ACS isolated from Lithospermum erythrorhizon inhibits LPS-induced nitric oxide (NO) and prostaglandin E2 (PGE2) release by suppressing the expression of inducible NO synthase (iNOS) and cyclooxygenase-2 (COX-2) in BV2 microglial cells. Furthermore, ACS reduced the LPS-induced DNA-binding activity of nuclear factor-κB (NF-κB) and subsequently suppressed iNOS and COX-2 expression. Consistent with these data, ACS attenuated the phosphorylation of PI3K and Akt and suppressed the DNA-binding activity of NF-κB by inducing the generation of reactive oxygen species (ROS) in LPS-stimulated cells. In addition, ACS enhanced heme oxygenase-1 (HO-1) expression via nuclear factor-erythroid 2-related factor 2 (Nrf2) activation. Zinc protoporphyrin, a specific HO-1 inhibitor, partially attenuated the antagonistic effects of ACS on LPS-induced NO and PGE2 production. By contrast, the presence of cobalt protoporphyrin, a specific HO-1 inducer, potently suppressed LPS-induced NO and PGE2 production. These data indicate that ACS downregulates proinflammatory mediators such as NO and PGE2 by suppressing PI3K/Akt-dependent NF-κB activity induced by ROS as well as inducing Nrf2-dependent HO-1 activity. Taken together, ACS might be a good candidate to regulate LPS-mediated inflammatory diseases.

Inhibiting microRNA-144 abates oxidative stress and reduces apoptosis in hearts of streptozotocin-induced diabetic mice

INTRODUCTION

Hyperglycemia-induced reactive oxygen species (ROS) generation contributes to the development of diabetic cardiomyopathy. However, little is known about the role of microRNAs in the regulation of ROS formation and myocardial apoptosis in streptozotocin (STZ)-induced diabetic mice.

METHODS AND RESULTS

It was observed that microRNA-144 (miR-144) level was lower in heart tissues of STZ-induced diabetic mice. High glucose exposure also reduced miR-144 levels in cultured cardiomyocytes. Moreover, miR-144 modulated high glucose-induced oxidative stress in cultured cardiomyocytes by directly targeting nuclear factor-erythroid 2-related factor 2 (Nrf2), which was a central regulator of cellular response to oxidative stress. The miR-144 mimics aggravated high glucose-induced ROS formation and apoptosis in cardiomyocytes, which could be attenuated by treatment with Dh404, an activator of Nrf2. Meanwhile, inhibition of miR-144 suppressed ROS formation and apoptosis induced by high glucose in cultured cardiomyocytes. What was more important is that reduced myocardial oxidative stress and apoptosis and improved cardiac function were identified in STZ-induced diabetic mice when treated with miR-144 antagomir.

CONCLUSION

Although miR-144 cannot explain the increased oxidative stress in STZ, therapeutic interventions directed at decreasing miR-144 may help to decrease oxidative stress in these hearts. Inhibition of miR-144 might have clinical potential to abate oxidative stress as well as to reduce cardiomyocyte apoptosis and improve cardiac function in diabetic cardiomyopathy.

Attenuation of Aβ25-35-induced parallel autophagic and apoptotic cell death by gypenoside XVII through the estrogen receptor-dependent activation of Nrf2/ARE pathways

Amyloid-beta (Aβ) has a pivotal function in the pathogenesis of Alzheimer's disease. To investigate Aβ neurotoxicity, we used an in vitro model that involves Aβ25-35-induced cell death in the nerve growth factor-induced differentiation of PC12 cells. Aβ25-35 (20μM) treatment for 24h caused apoptotic cell death, as evidenced by significant cell viability reduction, LDH release, phosphatidylserine externalization, mitochondrial membrane potential disruption, cytochrome c release, caspase-3 activation, PARP cleavage, and DNA fragmentation in PC12 cells. Aβ25-35 treatment led to autophagic cell death, as evidenced by augmented GFP-LC3 puncta, conversion of LC3-I to LC3-II, and increased LC3-II/LC3-I ratio. Aβ25-35 treatment induced oxidative stress, as evidenced by intracellular ROS accumulation and increased production of mitochondrial superoxide, malondialdehyde, protein carbonyl, and 8-OHdG. Phytoestrogens have been proved to be protective against Aβ-induced neurotoxicity and regarded as relatively safe targets for AD drug development. Gypenoside XVII (GP-17) is a novel phytoestrogen isolated from Gynostemma pentaphyllum or Panax notoginseng. Pretreatment with GP-17 (10μM) for 12h increased estrogen response element reporter activity, activated PI3K/Akt pathways, inhibited GSK-3β, induced Nrf2 nuclear translocation, augmented antioxidant responsive element enhancer activity, upregulated heme oxygenase 1 (HO-1) expression and activity, and provided protective effects against Aβ25-35-induced neurotoxicity, including oxidative stress, apoptosis, and autophagic cell death. In conclusion, GP-17 conferred protection against Aβ25-35-induced neurotoxicity through estrogen receptor-dependent activation of PI3K/Akt pathways, inactivation of GSK-3β and activation of Nrf2/ARE/HO-1 pathways. This finding might provide novel insights into understanding the mechanism for neuroprotective effects of phytoestrogens or gypenosides.

Anti-inflammatory effects of β-hydroxyisovalerylshikonin in BV2 microglia are mediated through suppression of the PI3K/Akt/NF-kB pathway and activation of the Nrf2/HO-1 pathway

In the present study, we investigated whether β-hydroxyisovalerylshikonin (β-HIVS) affects the production of proinflammatory mediators such as nitric oxide (NO) and prostaglandin E2 (PGE2) in BV2 microglial cells. Our data showed that β-HIVS inhibited secretion of NO and PGE2 and downregulated expression of their main regulatory genes, inducible NO synthesis (iNOS) and cyclooxygenase-2 (COX-2). β-HIVS also reduced the LPS-induced DNA-binding activity of nuclear factor-κB (NF-κB) by suppressing nuclear translocation of the NF-κB subunits and inhibiting the degradation and phosphorylation of IκBα. Furthermore, an NF-κB inhibitor, pyrrolidine dithiocarbamate (PDTC), attenuated LPS-stimulated iNOS and COX-2 expression, suggesting that NF-κB inhibition is a main effector in the expression of iNOS and COX-2. We also found that LPS-induced NF-κB activation is regulated through inhibition of PI3K/Akt phosphorylation in response to β-HIVS. Additionally, β-HIVS caused the induction of heme oxygenase-1 (HO-1) via upregulation of nuclear factor-erythroid 2-related factor 2 (Nrf2), both of which are involved in the secretion of proinflammatory mediators such as NO and PGE2. Taken together, our data indicate that β-HIVS diminishes the proinflammatory mediators NO and PGE2 and the expression of their regulatory genes, iNOS and COX-2, in LPS-stimulated BV2 microglial cells by inhibiting PI3K/Akt-dependent NF-κB activation and inducing Nrf2-mediated HO-1 expression.

Iron increases HMOX1 and decreases hepatitis C viral expression in HCV-expressing cells

AIM: To investigate effects of iron on oxidative stress, heme oxygenase-1 (HMOX1) and hepatitis C viral (HCV) expression in human hepatoma cells stably expressing HCV proteins.

METHODS: Effects of iron on oxidative stress, HMOX1, and HCV expression were assessed in CON1 cells. Measurements included mRNA by quantitative reverse transcription-polymerase chain reaction, and protein levels by Western blots.

RESULTS: Iron, in the form of ferric nitrilotriacetate, increased oxidative stress and up-regulated HMOX1 gene expression. Iron did not affect mRNA or protein levels of Bach1, a repressor of HMOX1. Silencing the up-regulation of HMOX1 nuclear factor-erythroid 2-related factor 2 (Nrf2) by Nrf2-siRNA decreased FeNTA-mediated up-regulation of HMOX1 mRNA levels. These iron effects were completely blocked by deferoxamine (DFO). Iron also significantly decreased levels of HCV core mRNA and protein by 80%-90%, nonstructural 5A mRNA by 90% and protein by about 50% in the Con1 full length HCV replicon cells, whereas DFO increased them.

CONCLUSION: Excess iron up-regulates HMOX1 and down-regulates HCV gene expression in hepatoma cells. This probably mitigates liver injury caused by combined iron overload and HCV infection.