Neuroprotection by Nrf2 via modulating microglial phenotype and phagocytosis after intracerebral hemorrhage

Activated microglia are divided into pro-inflammatory and anti-inflammatory functional states. In anti-inflammatory state, activated microglia contribute to phagocytosis, neural repair and anti-inflammation. Nrf2 as a major endogenous regulator in hematoma clearance after intracerebral hemorrhage (ICH) has received much attention. This study aims to investigate the mechanism underlying Nrf2-mediated regulation of microglial phenotype and phagocytosis in hematoma clearance after ICH. In vitro experiments, BV-2 cells were assigned to normal group and administration group (Nrf2-siRNA, Nrf2 agonists Monascin and Xuezhikang). In vivo experiments, mice were divided into 5 groups: sham, ICH + vehicle, ICH + Nrf2-/-, ICH + Monascin and ICH + Xuezhikang. In vitro and in vivo, 72 h after administration of Monascin and Xuezhikang, the expression of Nrf2, inflammatory-associated factors such as Trem1, TNF-α and CD80, anti-inflammatory, neural repair and phagocytic associated factors such as Trem2, CD206 and BDNF were analyzed by the Western blot method. In vitro, fluorescent latex beads or erythrocytes were uptaken by BV-2 cells in order to study microglial phagocytic ability. In vivo, hemoglobin levels reflect the hematoma volume. In this study, Nrf2 agonists (Monascin and Xuezhikang) upregulated the expression of Trem2, CD206 and BDNF while decreased the expression of Trem1, TNF-α and CD80 both in vivo and in vitro. At the same time, after Monascin and Xuezhikang treatment, the phagocytic capacity of microglia increased in vitro, neurological deficits improved and hematoma volume lessened in vivo. These results were reversed in the Nrf2-siRNA or the Nrf2-/- mice. All these results indicated that Nrf2 enhanced hematoma clearance and neural repair, improved neurological outcomes through enhancing microglial phagocytosis and alleviating neuroinflammation.

SQSTM1 Expression in Hepatocellular Carcinoma and Relation to Tumor Recurrence After Radiofrequency Ablation

BACKGROUND/AIMS

Autophagy is a process that allows the degradation of detrimental components through the lysosome to maintain cellular homeostasis under variable stimuli. SQSTM1 is a key molecule involved in functional autophagy and is linked to different signaling pathways, oxidative responses, and inflammation. Dysregulation of autophagy is reported in a broad spectrum of diseases. Accumulation of SQSTM1 reflects impaired autophagy, which is related to carcinogenesis and progression of various tumors, including hepatocellular carcinoma (HCC). This study investigated SQSTM1 protein expression in HCC and its relation to the clinicopathological features and the likelihood of tumor recurrence after radiofrequency ablation (RFA).

METHODS

This study included 50 patients with cirrhotic HCC of Barcelona Clinic Liver Cancer stages 0/A-B eligible for RFA. Tumor and peritumor biopsies were obtained just prior to local ablation and assessed for tumor pathological grade and SQSTM1 expression by immunohistochemistry. Patients were followed for one year after achieving complete ablation to detect any tumor recurrence.

RESULTS

Serum alpha-fetoprotein level (U = 149.50, P = 0.027∗) and pathological grade of the tumor (χ² = 12.702, P = 0.002∗) associated significantly with the tumor response to RFA. SQSTM1 expression level was significantly increased in HCC compared to the adjacent peritumor cirrhotic liver tissues (Z = 5.927, P < 0.001∗). Significant direct relation was found between SQSTM1 expression level in HCC and the pathological grade of the tumor (H = 33.789, P < 0.001∗). On follow-up, tumor and peritumor SQSTM1 expression levels performed significantly as a potential predictor of the overall survival, but not the disease recurrence.

CONCLUSIONS

SQSTM1 expression could determine aggressive HCC, even with reasonable tumor size and number, and identify the subset of HCC patients with short overall survival and unfavorable prognosis. SQSTM1 expression could not predict post-RFA intrahepatic HCC recurrence. SQSTM1 may be a potential biomarker and target for the selection of HCC patients for future therapies.

Artemisia judaica L. diminishes diabetes-induced reproductive dysfunction in male rats via activation of Nrf2/HO-1-mediated antioxidant responses

Diabetes mellitus is a well-known danger element for the progression of male reproductive dysfunctions. Available evidence supports oxidative stress to be the underlying mechanism for the manifestation of testicular dysfunctions during diabetes, and this relation represents an attractive target to antagonize these complications. Artemisia judaica L. is known to have antidiabetic and antioxidant characteristics. The possible protective effect of Artemisia judaica against diabetes-induced testicular disorders was not explored. In this investigation, we planned to estimate the possible protective effect of Artemisia judaica extract against diabetes-induced testicular disorders in male rats. The blood levels of insulin, glucose, glycosylated hemoglobin, testosterone, luteinizing hormone and follicle stimulating hormone were evaluated in rats after 12 weeks of Artemisia judaica treatment. Further, oxidative stress markers were determined in their testicular tissue. Epididymal fluid and testicular histological changes were also assessed. Expression of proliferating cell nuclear antigen has been evaluated in testis. Testicular mRNA expression of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1 as the significant transcription factors in controlling antioxidant system were evaluated by real-time polymerase chain reaction. Artemisia judaica extracts have the ability to ameliorate the elevation in the serum glucose and blood glycosylated hemoglobin and the reduction in insulin, testosterone, follicle stimulating hormone and luteinizing hormone caused by streptozotocin-induced diabetes. It induced a significant recovery of the testicular oxidative stress markers, sperm characteristics and improved histopathological findings of the testes. Treatment with Artemisia judaica extracts led to an increase in proliferating cell nuclear antigen protein expression. Reduction of testicular oxidative stress potential in streptozotocin-treated groups was confirmed by upregulation of nuclear factor erythroid 2-related factor 2 and heme oxygenase-1.

Role of pyroptosis in spinal cord injury and its therapeutic implications

BACKGROUND

Currently, spinal cord injury (SCI) is a pathological incident that triggers several neuropathological conditions, leading to the initiation of neuronal damage with several pro-inflammatory mediators' release. However, pyroptosis is recognized as a new programmed cell death mechanism regulated by the stimulation of caspase-1 and/or caspase-11/-4/-5 signaling pathways with a series of inflammatory responses.

AIM

Our current review concisely summarizes the potential role of pyroptosis-regulated programmed cell death in SCI, according to several molecular and pathophysiological mechanisms. This review also highlights the targeting of pyroptosis signaling pathways and inflammasome components and its therapeutic implications for the treatment of SCI.

KEY SCIENTIFIC CONCEPTS

Multiple pieces of evidence have illustrated that pyroptosis plays significant roles in cell swelling, plasma membrane lysis, chromatin fragmentation and intracellular pro-inflammatory factors including IL-18 and IL-1β release. In addition, pyroptosis is directly mediated by the recently discovered family of pore-forming protein known as GSDMD. Current investigations have documented that pyroptosis-regulated cell death plays a critical role in the pathogenesis of multiple neurological disorders as well as SCI. Our narrative article suggests that inhibiting the pyroptosis-regulated cell death and inflammasome components could be a promising therapeutic approach for the treatment of SCI in the near future.

Effect of Korean Red Ginseng on metabolic syndrome

Metabolic syndrome (MS) refers to a clustering of at least three of the following medical conditions: high blood pressure, abdominal obesity, hyperglycemia, low high-density lipoprotein level, and high serum triglycerides. MS is related to a wide range of diseases which includes obesity, diabetes, insulin resistance, cardiovascular disease, dyslipidemia, or non-alcoholic fatty liver disease. There remains an ongoing need for improved treatment strategies for MS. The most important risk factors are dietary pattern, genetics, old age, lack of exercise, disrupted biology, medication usage, and excessive alcohol consumption, but pathophysiology of MS has not been completely identified. Korean Red Ginseng (KRG) refers to steamed/dried ginseng, traditionally associated with beneficial effects such as anti-inflammation, anti-fatigue, anti-obesity, anti-oxidant, and anti-cancer effects. KRG has been often used in traditional medicine to treat multiple metabolic conditions. This paper summarizes the effects of KRG in MS and related diseases such as obesity, cardiovascular disease, insulin resistance, diabetes, dyslipidemia, or non-alcoholic fatty liver disease based on experimental research and clinical studies.

Amlodipine alleviates cisplatin-induced nephrotoxicity in rats through gamma-glutamyl transpeptidase (GGT) enzyme inhibition, associated with regulation of Nrf2/HO-1, MAPK/NF-κB, and Bax/Bcl-2 signaling

BACKGROUND

The therapeutic utility of the effective chemotherapeutic agent cisplatin is hampered by its nephrotoxic effect. We aimed from the current study to examine the possible protective effects of amlodipine through gamma-glutamyl transpeptidase (GGT) enzyme inhibition against cisplatin nephrotoxicity.

METHODS

Amlodipine (5 mg/kg, po) was administered to rats for 14 successive days. On the 10th day, nephrotoxicity was induced by a single dose of cisplatin (6.5 mg/kg, ip). On the last day, blood samples were collected for estimation of kidney function, while kidney samples were used for determination of GGT activity, oxidative stress, inflammatory, and apoptotic markers, along with histopathological evaluation.

RESULTS

Amlodipine alleviated renal injury that was manifested by significantly diminished serum creatinine and blood urea nitrogen levels, compared to cisplatin group. Amlodipine inhibited GGT enzyme, which participates in the metabolism of extracellular glutathione (GSH) and platinum-GSH-conjugates to a reactive toxic thiol. Besides, amlodipine diminished mRNA expression of NADPH oxidase in the kidney, while enhanced the anti-oxidant defense by activating Nrf2/HO-1 signaling. Additionally, it showed marked anti-inflammatory response by reducing expressions of p38 mitogen-activated protein kinase (p38 MAPK) and nuclear factor-kappa B (NF-κB), with subsequent down-regulation of tumor necrosis factor-alpha (TNF-α), interleukin-6 (IL-6), and vascular cell adhesion molecule-1 (VCAM-1). Moreover, amlodipine reduced Bax/Bcl-2 ratio and elevated hepatocyte growth factor (HGF), thus favoring renal cell survival.

CONCLUSIONS

Effective GGT inhibition by amlodipine associated with enhancement of anti-oxidant defense and suppression of inflammatory signaling and apoptosis support our suggestion that amlodipine could replace toxic GGT inhibitors in protection against cisplatin nephrotoxicity.

MicroRNAs and Xenobiotic Toxicity: An Overview

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miRNAs are key regulators of gene expression at both transcription and translation.

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The role of miRNAs in xenobiotic toxicity and its potential as biomarkers are being explored.

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In spite of numerous studies, the complex mechanism of miRNA biogenesis and its regulation remains unclear.

The advent of new technologies has paved the rise of various chemicals that are being employed in industrial as well as consumer products. This leads to the accumulation of these xenobiotic compounds in the environment where they pose a serious threat to both target and non-target species. miRNAs are one of the key epigenetic mechanisms that have been associated with toxicity by modulating the gene expression post-transcriptionally. Here, we provide a comprehensive view on miRNA biogenesis, their mechanism of action and, their possible role in xenobiotic toxicity. Further, we review the recent in vitro and in vivo studies involved in xenobiotic exposure induced miRNA alterations and the mRNA-miRNA interactions. Finally, we address the challenges associated with the miRNAs in toxicological studies.

Multiple binding modes of a small molecule to human Keap1 revealed by X-ray crystallography and molecular dynamics simulation

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Keap1 is useful target for the design of drugs that regulate the response to oxidative stresses.

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We determined two complex crystal structures of Keap1 with a small molecule ligand.

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The ligand binds to Keap1 so as to mimic the physiological substrate Nrf2.

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From molecular dynamics simulation results, the binding modes observed may be atypical in solution.

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Key residues for ligand binding are common between crystal and MD structures.

Keap1 protein acts as a cellular sensor for oxidative stresses and regulates the transcription level of antioxidant genes through the ubiquitination of a corresponding transcription factor, Nrf2. A small molecule capable of binding to the Nrf2 interaction site of Keap1 could be a useful medicine. Here, we report two crystal structures, referred to as the soaking and the cocrystallization forms, of the Kelch domain of Keap1 with a small molecule, Ligand1. In these two forms, the Ligand1 molecule occupied the binding site of Keap1 so as to mimic the ETGE motif of Nrf2, although the mode of binding differed in the two forms. Because the Ligand1 molecule mediated the crystal packing in both the forms, the influence of crystal packing on the ligand binding was examined using a molecular dynamics (MD) simulation in aqueous conditions. In the MD structures from the soaking form, the ligand remained bound to Keap1 for over 20 ns, whereas the ligand tended to dissociate in the cocrystallization form. The MD structures could be classified into a few clusters that were related to but distinct from the crystal structures, indicating that the binding modes observed in crystals might be atypical of those in solution. However, the dominant ligand recognition residues in the crystal structures were commonly used in the MD structures to anchor the ligand. Therefore, the present structural information together with the MD simulation will be a useful basis for pharmaceutical drug development.