Oltipraz Prevents High Glucose-Induced Oxidative Stress and Apoptosis in RSC96 Cells through the Nrf2/NQO1 Signalling Pathway

Effects of Oltipraz on the Glycolipid Metabolism and the Nrf2/HO-1 Pathway in Type 2 Diabetic Mice

Purpose

Oltipraz has various applications, including for treating cancer, liver fibrosis, and cirrhosis. However, its role in regulating metabolic processes, inflammation, oxidative stress, and insulin resistance in STZ-induced T2DM remains unclear. Hence, a comprehensive understanding of how oltipraz ameliorates diabetes, particularly inflammation and oxidative stress, is imperative.

Methods

The negative control (NC), T2DM model (T2DM), and T2DM models treated with oltipraz (OLTI) and metformin (MET) were constructed. The RNA sequencing (RNA-Seq) was performed on the pancreatic tissues. H&E staining was conducted on the liver and pancreatic tissues. The intraperitoneal glucose tolerance test (IPGTT), blood glucose and lipids, inflammatory factors, and oxidative stress indexes were measured. qPCR and Western blotting examined the nuclear factor erythroid-derived 2-like 2 (Nrf2)/ hemoglobin-1 (HO-1) signaling pathway, cell apoptosis-related genes, and Reg3g levels. Immunofluorescence (IF) analysis of the pancreas was performed to measure insulin secretion.

Results

A total of 256 DEGs were identified in OLTI_vs_T2DM, and they were mainly enriched in circadian rhythm, cAMP, AMPK, insulin, and MAPK signaling pathways. Moreover, Reg3g exhibits reduced expression in T2DM_vs_NC, and elevated expression in OLTI_vs_T2DM, yet remains unchanged in MET_vs_T2DM. OLTI reduced fasting blood glucose and alleviated T2DM-induced weight loss. It improved blood glucose and insulin resistance, decreased blood lipid metabolism, reduced inflammation and oxidative stress through the Nrf2/HO-1 signaling pathway, mitigated pancreatic and liver tissue injury, and enhanced pancreatic β-cell insulin secretion. OLTI exhibited anti-apoptosis effects in T2DM. Moreover, OLTI exhibits superior antioxidant activity than metformin.

Conclusion

In summary, OLTI improves blood glucose and insulin resistance, decreases blood lipid metabolism, reduces inflammation and apoptosis, suppresses oxidative stress through the Nrf2/HO-1 signaling pathway, mitigates pancreatic and liver tissue injury, and enhances pancreatic β-cell insulin secretion, thereby mitigating T2DM symptoms. Moreover, Reg3g could be an important target for OLTI treatment of T2DM.

Bioinformatics and validation reveal the potential target of curcumin in the treatment of diabetic peripheral neuropathy

Diabetic peripheral neuropathy (DPN) is a common nerve-damaging complication of diabetes mellitus. Effective treatments are needed to alleviate and reverse diabetes-associated damage to the peripheral nerves. Curcumin is an effective neuroprotectant that plays a protective role in DPN promoted by Schwann cells (SCs) lesions. However, the potential molecular mechanism of curcumin remains unclear. Therefore, our aim is to study the detailed molecular mechanism of curcumin-mediated SCs repair in order to improve the efficacy of curcumin in the clinical treatment of DPN. First, candidate target genes of curcumin in rat SC line RSC96 cells stimulated by high glucose were identified by RNA sequencing and bioinformatic analyses. Enrichment analysis of Gene Ontology (GO) and Kyoto Encyclopedia of Genes and Genomes (KEGG) was carried out by Metascape, followed by 8 algorithms on Cytoscape to determine 4 hub genes, namly Hmox1, Pten, Vegfa and Myc. Next, gene set enrichment analysis (GSEA) and Pearson function showed that Hmox1 was significantly correlated with apoptosis. Subsequently, qRT-PCR, MTT assay, flow cytometry, caspase-3 activity detection and westernblot showed that curcumin treatment increased RSC96 cell viability, reduced cell apoptosis, increased Hmox1, Pten, Vegfa and Myc expression, and up-regulated Akt phosphorylation level under high glucose environment. Finally, molecular docking predicted the binding site of curcumin to Hmox1. These results suggest that curcumin can reduce the apoptosis of SCs induced by high glucose, and Hmox1 is a potential target for curcumin. Our findings provide new insights about the mechanism of action of curcumin on SC as a potential treatment in DPN.

The size-dependent effects of nanoplastics in mouse primary hepatocytes from cells to molecules

Nanoplastics (NPs) are easily ingested by organisms and their major accumulation organ was determined to be liver. To date, the size-dependent cytotoxicity of NPs on mammalian hepatocytes remains unclear. This study utilized mouse primary hepatocytes and catalase (CAT) as specific receptors to investigate the toxicity of NPs from cells to molecules, focusing on size-dependent effects. Results showed that the larger the particle size of NP at low doses (≤50 mg/L), the most pronounced inhibitory effect on hepatocyte viability. 20 nm NPs significantly inhibit cell viability only at high doses (100 mg/L). Larger NP particles (500 nm and 1000 nm) resulted in a massive release of lactate dehydrogenase (LDH) from the cell (cell membrane damage). Reactive oxygen species (ROS), superoxide dismutase (SOD) and CAT tests suggest that NPs disturbed the cellular antioxidant system. 20 nm NPs show great strength in oxidizing lipids and disrupting mitochondrial function compared to NPs of other particle sizes. The degree of inhibition of CAT activity by different sized NPs was coherent at the cellular and molecular levels, and NP-500 had the most impact. This suggests that the structure and microenvironment of the polypeptide chain in the vicinity of the CAT active site is more susceptible to proximity and alteration by NP-500. In addition, the smaller NPs are capable of inducing relaxation of CAT backbone, disruption of H-bonding and reduction of α-helix content, whereas the larger NPs cause contraction of CAT backbone and increase in α-helix content. All NPs induce CAT fluorescence sensitization and make the chromophore microenvironment hydrophobic. This study provides new insights for NP risk assessment and applications.

Different Types of Cell Death in Diabetic Neuropathy: A Focus on Mechanisms and Therapeutic Strategies

Diabetic neuropathy (DN) is a common complication of diabetes, affecting over 50% of patients, leading to significant pain and a burden. Currently, there are no effective treatments available. Cell death is considered a key factor in promoting the progression of DN. This article reviews how cell death is initiated in DN, emphasizing the critical roles of oxidative stress, mitochondrial dysfunction, inflammation, endoplasmic reticulum stress, and autophagy. Additionally, we thoroughly summarize the mechanisms of cell death that may be involved in the pathogenesis of DN, including apoptosis, autophagy, pyroptosis, and ferroptosis, among others, as well as potential therapeutic targets offered by these death mechanisms. This provides potential pathways for the prevention and treatment of diabetic neuropathy in the future.

Unleashing the Potential of Nrf2: A Novel Therapeutic Target for Pulmonary Vascular Remodeling

Pulmonary vascular remodeling, characterized by the thickening of all three layers of the blood vessel wall, plays a central role in the pathogenesis of pulmonary hypertension (PH). Despite the approval of several drugs for PH treatment, their long-term therapeutic effect remains unsatisfactory, as they mainly focus on vasodilation rather than addressing vascular remodeling. Therefore, there is an urgent need for novel therapeutic targets in the treatment of PH. Nuclear factor erythroid 2-related factor 2 (Nrf2) is a vital transcription factor that regulates endogenous antioxidant defense and emerges as a novel regulator of pulmonary vascular remodeling. Growing evidence has suggested an involvement of Nrf2 and its downstream transcriptional target in the process of pulmonary vascular remodeling. Pharmacologically targeting Nrf2 has demonstrated beneficial effects in various diseases, and several Nrf2 inducers are currently undergoing clinical trials. However, the exact potential and mechanism of Nrf2 as a therapeutic target in PH remain unknown. Thus, this review article aims to comprehensively explore the role and mechanism of Nrf2 in pulmonary vascular remodeling associated with PH. Additionally, we provide a summary of Nrf2 inducers that have shown therapeutic potential in addressing the underlying vascular remodeling processes in PH. Although Nrf2-related therapies hold great promise, further research is necessary before their clinical implementation can be fully realized.

Serum Uric Acid Levels Are Related to Diabetic Peripheral Neuropathy, Especially for Motor Conduction Velocity of Tibial Nerve in Type 2 Diabetes Mellitus Patients

Background

Oxidative stress is one of the most critical factors that contribute to the pathogenesis of neuronal damage, including diabetic peripheral neuropathy (DPN). Uric acid is a kind of natural antioxidant that plays a major role in the antioxidant capacity against oxidative stress. Here, we aim to determine the role of serum uric acid (SUA) in the DPN of patients with type 2 diabetes mellitus (T2DM). Patients and Methods. 106 patients with T2DM were recruited and divided into the DPN group and the control group. Clinical parameters, especially for motor nerve fiber conduction velocity and sensory nerve fiber conduction velocity, were collected. Differences between T2DM patients with and without DPN were compared. Correlation and regression analyses were performed to explore the association between SUA and DPN.

Results

Compare with 57 patients with DPN, 49 patients without DPN showed lower HbA1c and elevated SUA levels. Additionally, SUA levels are negatively associated with the motor conduction velocity of tibial nerve with or without adjusting for HbA1c. Besides, it is suggested that decreased SUA levels may influence the motor conduction speed of the tibial nerve by multiple linear regression analysis. Moreover, we demonstrated that decreased SUA level is a risk factor for DPN in patients with T2DM by binary logistic regression analysis.

Conclusion

Lower SUA is a risk factor for DPN in patients with T2DM. Additionally, decreased SUA may influence the damage of peripheral neuropathy, especially for motor conduction velocity of the tibial nerve.

Fibrosis: Types, Effects, Markers, Mechanisms for Disease Progression, and Its Relation with Oxidative Stress, Immunity, and Inflammation

Most chronic inflammatory illnesses include fibrosis as a pathogenic characteristic. Extracellular matrix (ECM) components build up in excess to cause fibrosis or scarring. The fibrotic process finally results in organ malfunction and death if it is severely progressive. Fibrosis affects nearly all tissues of the body. The fibrosis process is associated with chronic inflammation, metabolic homeostasis, and transforming growth factor-β1 (TGF-β1) signaling, where the balance between the oxidant and antioxidant systems appears to be a key modulator in managing these processes. Virtually every organ system, including the lungs, heart, kidney, and liver, can be affected by fibrosis, which is characterized as an excessive accumulation of connective tissue components. Organ malfunction is frequently caused by fibrotic tissue remodeling, which is also frequently linked to high morbidity and mortality. Up to 45% of all fatalities in the industrialized world are caused by fibrosis, which can damage any organ. Long believed to be persistently progressing and irreversible, fibrosis has now been revealed to be a very dynamic process by preclinical models and clinical studies in a variety of organ systems. The pathways from tissue damage to inflammation, fibrosis, and/or malfunction are the main topics of this review. Furthermore, the fibrosis of different organs with their effects was discussed. Finally, we highlight many of the principal mechanisms of fibrosis. These pathways could be considered as promising targets for the development of potential therapies for a variety of important human diseases.

Inhibiting apoptosis of Schwann cell under the high-glucose condition: A promising approach to treat diabetic peripheral neuropathy using Chinese herbal medicine

Diabetic peripheral neuropathy (DPN) is a common complication of diabetes. Glycemic control and lifestyle alterations cannot prevent the development of DPN; therefore, investigating effective treatments for DPN is crucial. Schwann cells (SCs) maintain the physiological function of peripheral nerves and promote the repair and regeneration of injured nerves. Inhibiting the apoptosis of SCs through various pathological pathways in a high-glucose environment plays an important role in developing DPN. Therefore, inhibiting the apoptosis of SCs can be a novel treatment strategy for DPN. Previous studies have indicated the potential of Chinese herbal medicine (CHM) in treating DPN. In this study, we have reviewed the effects of CHM (both monomers and extracts) on the apoptosis of SCs by interfering with the production of advanced glycation end products, oxidative stress, and endoplasmic reticulum stress pathological pathways. This review will demonstrate the potentialities of CHM in inhibiting apoptosis in SCs, providing new insights and perspectives for treating DPN.

Sulforaphane alleviates high fat diet-induced insulin resistance via AMPK/Nrf2/GPx4 axis

Insulin resistance is a characteristic feature of type 2 diabetes. Sulforaphane (SFN) is a natural antioxidant extracted from the cruciferous vegetables. Recent study reported that SFN exhibits excellent anti-diabetic effects, however, the underlying mechanism is still unclear. This study aimed to investigate the therapeutic effects of SFN on a high-fat diet (HFD)-induced insulin resistance and potential mechanism. SFN was found to effectively reduce body weight, fasting blood glucose and hyperlipidemia, and improve liver function in HFD-fed mice. Furthermore, SFN effectively increased glucose uptake and improved insulin signaling in palmitic acid (PA)-induced HepG2 cells. SFN also led to increased expression of antioxidant genes downstream of Nrf2 and decreased accumulation of lipid peroxides MDA and 4-HNE, both in vivo and in vitro. Further studies revealed that SFN significantly reduced glutathione peroxidase 4 (GPx4) inactivation-mediated oxidative stress by activating the AMPK and Nrf2 signaling pathways. In PA-induced HepG2 cells and flies, the alleviation of insulin resistance by SFN was diminished by GPx4 inhibitor. Taken together, SFN ameliorated HFD-induced insulin resistance by activating the AMPK-Nrf2-GPx4 pathway, providing new insights into SFN as a therapeutic compound for the alleviation of insulin resistance.

Molecular mechanism of two functional protein structure changes under 2,3-butanedione-induced oxidative stress and apoptosis effects in the hepatocytes

Food security has become closely watched with the occurrence of a series of food safety incidents in recent years. The widespread adoption of 2,3-butanedione (BUT), as a food additive, is an unpreventable significant risk factor to food security. Based on this, mouse hepatocyte AML-12 cells and two functional proteins (bovine serum albumin and lysozyme) were utilized as targeted receptors to study the adverse effects of BUT at the cellular and molecular levels. Results suggested that BUT could disrupt the redox balance of AML-12 cells, reducing glutathione (GSH) activity fell to 87.18 %, which cannot offset the production of reactive oxygen species (ROS). Meanwhile, the increasement of lipid peroxidation and malondialdehyde (MDA) levels were observed. The mitochondrial membrane function was also abnormal due to the excessive accumulation of ROS and eventually leads to cell apoptosis and death. At the molecular level, the exposure of BUT could alter the skeleton and secondary structure of bovine serum albumin (BSA) and lysozyme (LYZ), and it could statically quench the intrinsic fluorescence of proteins. The combined experiments confirmed proved the potentially toxic effects of BUT accumulation on the detoxification organ, providing theoretical support for the liver diseases caused by BUT exposure, and a reference for the risk assessment of occupational exposure of BUT.

The Role of Organosulfur Compounds as Nrf2 Activators and Their Antioxidant Effects

Nuclear factor erythroid 2-related factor 2 (Nrf2) signaling has become a key pathway for cellular regulation against oxidative stress and inflammation, and therefore an attractive therapeutic target. Several organosulfur compounds are reportedly activators of the Nrf2 pathway. Organosulfur compounds constitute an important class of therapeutic agents in medicinal chemistry due to their ability to participate in biosynthesis, metabolism, cellular functions, and protection of cells from oxidative damage. Sulfur has distinctive chemical properties such as a large number of oxidation states and versatility of reactions that promote fundamental biological reactions and redox biochemistry. The presence of sulfur is responsible for the peculiar features of organosulfur compounds which have been utilized against oxidative stress-mediated diseases. Nrf2 activation being a key therapeutic strategy for oxidative stress is closely tied to sulfur-based chemistry since the ability of compounds to react with sulfhydryl (-SH) groups is a common property of Nrf2 inducers. Although some individual organosulfur compounds have been reported as Nrf2 activators, there are no papers with a collective analysis of these Nrf2-activating organosulfur compounds which may help to broaden the knowledge of their therapeutic potentials and motivate further research. In line with this fact, for the first time, this review article provides collective and comprehensive information on Nrf2-activating organosulfur compounds and their therapeutic effects against oxidative stress, thereby enriching the chemical and pharmacological diversity of Nrf2 activators.

Preventive effect of Lactobacillus plantarum HFY15 on carbon tetrachloride (CCl4 )-induced acute liver injury in mice

Carbon tetrachloride (CCl4 ) is the main chemical causing liver damage. In this experiment, the effect of Lactobacillus plantarum HFY15 treatment on CCl4 -induced acute liver injury was investigated using mice. Fifty adult mice were randomized into five study groups, each group with 10 ml kg-1 saline, 50 mg kg-1 silymarin, and 109 CFU kg-1 L. plantarum HFY15 and LDSB per day, and all the mice expect the normal group were injected 0.8% CCl4 (10 ml kg-1 ) on the 14th day. Following the 16 h induction of the liver injury, various biochemical markers were assessed for blood and liver tissue. After L. plantarum HFY15 treatment, the content of alanine aminotransferase (ALT), aspartate aminotransferase (AST), triglycerides (TG), malondialdehyde (MDA), and reactive oxygen species (ROS) in serum decreased by 67.7%, 65.0%, 41.9%, 59.5%, and 51.5%, respectively, and the level of antioxidant enzymes (total superoxide dismutation [T-SOD], catalase [CAT], glutathione [GSH]) increased by more than twofold. Pro-inflammatory cytokine interleukin-6 (IL-6), interferon-γ (INF-γ), and tumor necrosis factor-α (TNF-α) decreased by more than 45% in serum and live. What is more, L. plantarum HFY15 increased the expression of antiapoptosis genes Bcl-2 by eightfold, inhibiting the expression of proapoptotic genes Caspase-3 and Bax by about threefold. Lactobacillus plantarum HFY15 has obvious protective effects on CCl4 -induced liver injury by inhibiting oxidation, reducing the release of inflammatory factors, and exerting suppressive effect on apoptotic process in the CCl4 -induced liver injury. Lactobacillus plantarum HFY15 can be developed as edible lactic acid bacteria for preventing liver toxicity. PRACTICAL APPLICATION: L. plantarum HFY15 can alleviate liver injury caused by carbon tetrachloride toxicity through antioxidant, anti-inflammatory and anti-apoptotic pathways.

Targeting NRF2 in Type 2 diabetes mellitus and depression: Efficacy of natural and synthetic compounds

Evidence supports a strong bidirectional association between depression and Type 2 diabetes mellitus (T2DM). The harmful impact of oxidative stress and chronic inflammation on the development of both disorders is widely accepted. Nuclear factor erythroid 2-related factor 2 (NRF2) is a pertinent target in disease management owing to its reputation as the master regulator of antioxidant responses. NRF2 influences the expression of various cytoprotective phase 2 antioxidant genes, which is hampered in both depression and T2DM. Through interaction and crosstalk with several signaling pathways, NRF2 endeavors to contain the widespread oxidative damage and persistent inflammation involved in the pathophysiology of depression and T2DM. NRF2 promotes the neuroprotective and insulin-sensitizing properties of its upstream and downstream targets, thereby interrupting and preventing disease advancement. Standard antidepressant and antidiabetic drugs may be powerful against these disorders, but unfortunately, they come bearing distressing side effects. Therefore, exploiting the therapeutic potential of NRF2 activators presents an exciting opportunity to manage such bidirectional and comorbid conditions.

The Effects of Nuclear Factor Erythroid 2 (NFE2)-Related Factor 2 (Nrf2) Activation in Preclinical Models of Peripheral Neuropathic Pain

Oxidative stress, resulting from an imbalance between the formation of damaging free radicals and availability of protective antioxidants, can contribute to peripheral neuropathic pain conditions. Reactive oxygen and nitrogen species, as well as products of the mitochondrial metabolism such as superoxide anions, hydrogen peroxide, and hydroxyl radicals, are common free radicals. Nuclear factor erythroid 2 (NFE2)-related factor 2 (Nrf2) is a transcription factor encoded by the NFE2L2 gene and is a member of the cap 'n' collar subfamily of basic region leucine zipper transcription factors. Under normal physiological conditions, Nrf2 remains bound to Kelch-like ECH-associated protein 1 in the cytoplasm that ultimately leads to proteasomal degradation. During peripheral neuropathy, Nrf2 can translocate to the nucleus, where it heterodimerizes with muscle aponeurosis fibromatosis proteins and binds to antioxidant response elements (AREs). It is becoming increasingly clear that the Nrf2 interaction with ARE leads to the transcription of several antioxidative enzymes that can ameliorate neuropathy and neuropathic pain in rodent models. Current evidence indicates that the antinociceptive effects of Nrf2 occur via reducing oxidative stress, neuroinflammation, and mitochondrial dysfunction. Here, we will summarize the preclinical evidence supporting the role of Nrf2 signaling pathways and Nrf2 inducers in alleviating peripheral neuropathic pain.

Discrepancy of apoptotic events in mouse hepatocytes and catalase performance: Size-dependent cellular and molecular toxicity of ultrafine carbon black

The diversification of the production process and application of ultrafine carbon black (UFCB), one of the nanomaterials, make the difference in particle sizes that exposed to environment. Currently, few size-dependent toxicity studies of UFCB pay attention to targeted effects on detoxification organs. And there is a research gap in the size-dependent molecular toxicity of UFCB. Based on this, mouse hepatocytes and catalase (CAT) were used as targeted receptors for UFCB size-dependent cellular and molecular toxicity studies. Results indicate that UFCB_13 nm induced higher ROS and lipid peroxidation levels. And the cell viability decreased to 22.5%, which is sharp contrast to UFCB_50 nm (45.3%) and UFCB_95 nm (55.1%). Mitochondrial dysfunction and a 25.2% early apoptosis rate are the further manifestation of the stronger cytotoxicity of UFCB_13 nm. At the molecular level, the exposure of UFCB with better dispersity resulted in more significant changes in the CAT backbone and secondary structure, fluorescence sensitization and enzyme function inhibition. The combined experiments show that the cellular uptake and dispersity of UFCB are the dominating factors for the discrepancy in size-dependent cellular and molecular toxicity, respectively. This study provides a theoretical basis for the necessary circumvention and substitution of UFCB in engineering applications.

Chlamydia trachomatis Pgp3 protein regulates oxidative stress via activation of the Nrf2/NQO1 signal pathway

AIM

Chlamydia trachomatis has evolved various strategies to alleviate oxidative stress of host cells to maintain their intracellular survival. However, the exact mechanism of anti-oxidative stress of C. trachomatis is still unclear. The activation of nuclear factor erythroid 2-related factor 2/quinone oxidoreductase (Nrf2/NQO1) signal pathway has been identified as an efficient antioxidant defensive mechanism used by host cells to counteract oxidative stress. Pgp3 is a pivotal virulence factor of C. trachomatis involved in intracellular survival. The aim of this study is to explore the role of Pgp3 on Nrf2/NQO1 signal pathway against oxidative stress.

MAIN METHODS

After HeLa cells were stimulated with Pgp3 protein, Nrf2 location and the inclusion bodies of C. trachomatis were detected by indirect immunofluorescence, western blotting and Oxidative stress assay kits were used to separately determine the protein expression and the content of malondialdehyde (MDA), superoxide dismutase (SOD) and total antioxidant capacity (T-AOC) before and after the interference of Nrf-2 and NQO1.

KEY FINDINGS

Pgp3 promoted the nuclear translocation of Nrf2 to increase NQO1 expression and reduced oxidative stress induced by LPS to contribute to the survival of C. trachomatis. Inhibition of Nrf2/NQO1 signal pathway with Nrf2 inhibitor and down-regulation of NQO1 with siRNA-NQO1 suppressed oxidative stress resistance induced by Pgp3.

SIGNIFICANCE

Here we found that Pgp3 alleviated oxidative stress to promote the infectivity of C. trachomatis through activation of Nrf2/NQO1 signal pathway, which provided a novel understanding of the effects of Pgp3 in the pathogenesis of C. trachomatis.