DJ-1 protects retinal pericytes against high glucose-induced oxidative stress through the Nrf2 signaling pathway

Resilience to diabetic retinopathy

Chronic elevation of blood glucose at first causes relatively minor changes to the neural and vascular components of the retina. As the duration of hyperglycemia persists, the nature and extent of damage increases and becomes readily detectable. While this second, overt manifestation of diabetic retinopathy (DR) has been studied extensively, what prevents maximal damage from the very start of hyperglycemia remains largely unexplored. Recent studies indicate that diabetes (DM) engages mitochondria-based defense during the retinopathy-resistant phase, and thereby enables the retina to remain healthy in the face of hyperglycemia. Such resilience is transient, and its deterioration results in progressive accumulation of retinal damage. The concepts that co-emerge with these discoveries set the stage for novel intellectual and therapeutic opportunities within the DR field. Identification of biomarkers and mediators of protection from DM-mediated damage will enable development of resilience-based therapies that will indefinitely delay the onset of DR.

Interplay of human gastrointestinal microbiota metabolites: Short-chain fatty acids and their correlation with Parkinson's disease

Short-chain fatty acids (SCFAs) are, the metabolic byproducts of intestinal microbiota that, are generated through anaerobic fermentation of undigested dietary fibers. SCFAs play a pivotal role in numerous physiological functions within the human body, including maintaining intestinal mucosal health, modulating immune functions, and regulating energy metabolism. In recent years, extensive research evidence has indicated that SCFAs are significantly involved in the onset and progression of Parkinson disease (PD). However, the precise mechanisms remain elusive. This review comprehensively summarizes the progress in understanding how SCFAs impact PD pathogenesis and the underlying mechanisms. Primarily, we delve into the synthesis, metabolism, and signal transduction of SCFAs within the human body. Subsequently, an analysis of SCFA levels in patients with PD is presented. Furthermore, we expound upon the mechanisms through which SCFAs induce inflammatory responses, oxidative stress, abnormal aggregation of alpha-synuclein, and the intricacies of the gut-brain axis. Finally, we provide a critical analysis and explore the potential therapeutic role of SCFAs as promising targets for treating PD.

The antioxidant effect of tetrahedral framework nucleic acid-based delivery of small activating RNA targeting DJ-1 on retinal oxidative stress injury

Age-related macular degeneration (AMD) and diabetic retinopathy (DR) are the world's leading causes of blindness. The retinal pigment epithelium (RPE) and vascular endothelial cell exposed to oxidative stress is the major cause of AMD and DR. DJ-1, an important endogenous antioxidant, its overexpression is considered as a promising antioxidant treatment for AMD and DR. Here, we modified the tetrahedral frame nucleic acids (tFNAs) with DJ-1 saRNAs as a delivery system, and synthesized a novel nanocomplex (tFNAs-DJ-1 saRNAs). In vitro studies show that tFNAs-DJ-1 saRNAs can efficiently transfer DJ-1 saRNAs to human umbilical vein endothelial cells (HUVECs) and ARPE-19s, and significantly increased their cellular DJ-1 level. Reactive oxygen species expression in H2O2-treated HUVECs and ARPE-19s were decreased, cell viability was enhanced and cell apoptosis were inhibited when tFNAs-DJ-1 saRNAs were delivered. Moreover, tFNAs-DJ-1 saRNAs preserved mitochondrial structure and function under oxidative stress conditions. In the aspect of molecular mechanism, tFNAs-DJ-1 saRNAs activated Erk and Nrf2 pathway, which might contribute to its protective effects against oxidative stress damage. To conclude, this study shows the successfully establishment of a simple but effective delivery system of DJ-1 saRNAs associated with antioxidant effects in AMD and DR, which may be a promising agent for future treatment in oxidative stress-related retinal disorders.

Nrf-2-dependent antioxidant and anti-inflammatory effects underlie the protective effect of esculeoside A against retinal damage in streptozotocin-induced diabetic rats

Esculeoside A (ESA) is a tomato-derived glycoside with antioxidant and anti-inflammatory properties. The protective effect of ESA against diabetic retinopathy is not well-investigated and was the core objective of this study. In addition, we tested if such protection involves the activation of Nrf2 signaling. Type 1 diabetes mellitus (T1DM) was induced in adult Wistar male rats by an intraperitoneal injection of streptozotocin (65 mg/kg). Non-diabetic and T1DM rats were divided into two subgroup groups given either the vehicle or ESA (100 mg)/kg. An additional T1DM group was given ESA (100 mg/kg) and an Nrf2 inhibitor (2 mg/kg) (n=8 rats/group). Treatments continued for 12 weeks. In this study, according to the histological features, ESA improved the structure of ganglionic cells and increased the number of cells of the inner nuclear and plexiform layers in the retinas of T1DM rats. Concomitantly, it reduced the retina levels of malondialdehyde (lipid peroxides), vascular endothelial growth factor, interleukin-6, tumor necrosis factor-α, Bax, and caspase-3. In the retinas of the control and diabetic rats, ESA boosted the levels of total glutathione, superoxide dismutase, heme-oxygenase-1, and Bcl2, reduced the mRNA levels of REDD1, and enhanced cytoplasmic and nuclear levels of Nrf2. However, ESA failed to alter the mRNA levels of Nrf2 and keap1, protein levels of keap1, plasma glucose, plasma insulin, serum triglycerides, cholesterol, and LDL-c in both the control and T1DM rats. In conclusion, ESA alleviates retinopathy in T1DM rats by suppressing REDD1-associated degradation and inhibiting the Nrf2/antioxidant axis.

Park7 protects retinal ganglion cells and promotes functional preservation after optic nerve crush via regulation of the Nrf2 signaling pathway

PURPOSE

We aim to investigate the effect of Park7 on mice RGC survival and function following optic nerve crush (ONC), and to explore its potential mechanism.

METHODS

Wild-type male C57BL/6J mice were subjected to optic nerve crush. Six weeks before ONC, mice received rAAV-shRNA (Park7)-EGFP or rAAV-EGFP intravitreally. Western blotting was used to detect Park7 levels. RGC survival was measured using immunofluorescence. Retinal cell apoptosis was detected using terminal deoxynucleotidyl transferase nick-end-labelling. An electroretinogram (ERG) and the optomotor response (OMR) were used to assess RGC function. Kelch-like ECH-associated protein 1 (Keap1), nuclear factor erythroid 2-related factor (Nrf2), and heme oxygenase 1 (HO-1) levels were assessed using western blotting.

RESULTS

ONC injury increased the relative expression of Park7 significantly and decreased RGC survival, the amplitude of the photopic negative response (PhNR), and OMR. Intravitreal injection of rAAV-shRNA(Park7)-EGFP downregulated Park7 expression and was clearly demonstrated by the green fluorescence protein in many retinal layers. Moreover, Park7 downregulation aggravated the decrease in RGC survival and amplitude of PhNR as well as the visual acuity after ONC. However, inhibition of Park7 significantly increased Keap1 levels, decreased the total and nuclear Nrf2 levels, and reduced HO-1 levels.

CONCLUSIONS

Park7 downregulation enhanced RGC injury and decreased retinal electrophysiological response and OMR after ONC in mice via the Keap1-Nrf2-HO-1 signaling pathway. Park7 may have neuroprotective effects and could represent a novel way to treat optic neuropathy.

Ulmus davidiana 60% edible ethanolic extract for prevention of pericyte apoptosis in diabetic retinopathy

Diabetic retinopathy (DR) is a disease that causes visual deficiency owing to vascular leakage or abnormal angiogenesis. Pericyte apoptosis is considered one of the main causes of vascular leakage in diabetic retina, but there are few known therapeutic agents that prevent it. Ulmus davidiana is a safe natural product that has been used in traditional medicine and is attracting attention as a potential treatment for various diseases, but its effect on pericyte loss or vascular leakage in DR is not known at all. In the present study, we investigated on the effects of 60% edible ethanolic extract of U. davidiana (U60E) and catechin 7-O-β-D-apiofuranoside (C7A), a compound of U. davidiana, on pericyte survival and endothelial permeability. U60E and C7A prevented pericyte apoptosis by inhibiting the activation of p38 and JNK induced by increased glucose and tumor necrosis factor alpha (TNF-α) levels in diabetic retina. Moreover, U60E and C7A reduced endothelial permeability by preventing pericyte apoptosis in co-cultures of pericytes and endothelial cells. These results suggest that U60E and C7A could be a potential therapeutic agent for reducing vascular leakage by preventing pericyte apoptosis in DR.

Traversing through the cell signaling pathways of neuroprotection by betanin: therapeutic relevance to Alzheimer's Disease and Parkinson's Disease

Modulation of cell signaling pathways is the key area of research towards the treatment of neurodegenerative disorders. Altered Nrf2-Keap1-ARE (Nuclear factor erythroid-2-related factor 2-Kelch-like ECH-associated protein 1-Antioxidant responsive element) and SIRT1 (Sirtuin 1) cell signaling pathways are considered to play major role in the etiology and pathogenesis of Alzheimer's disease (AD) and Parkinson's disease (PD). Strikingly, betanin, a betanidin 5-O-β-D-glucoside compound is reported to show commendable anti-oxidative, anti-inflammatory and anti-apoptotic effects in several disease studies including AD and PD. The present review discusses the pre-clinical studies demonstrating the neuroprotective effects of betanin by virtue of its potential to ameliorate oxidative stress, neuroinflammation, abnormal protein aggregation and cell death. It highlights the direct linkage between the neuroprotective abilities of betanin and upregulation of the Nrf2-Keap1-ARE and SIRT1 signaling pathways. The review further hypothesizes the involvement of the betanin-Nrf2-ARE route in the inhibition of beta-amyloid aggregation through beta-site amyloid precursor protein cleaving enzyme 1 (BACE1), one of the pivotal hallmarks of AD. The present review hereby for the first time elaborately discusses the reported neuroprotective abilities of betanin and decodes the Nrf2 and SIRT1 modulating potential of betanin as a primary mechanism of action behind, hence highlighting it as a novel drug candidate for the treatment of neurodegenerative diseases in the near future.

Ferroptosis: mechanisms and advances in ocular diseases

As an essential trace element in the body, iron is critical for the maintenance of organismal metabolism. Excessive iron facilitates reactive oxygen species generation and inflicts damage on cells and tissues. Ferroptosis, a newly identified iron-dependent type of programmed cell death, has been implicated in a broad set of metabolic disorders. Ferroptosis is mainly characterized by excess iron accumulation, elevated lipid peroxides and reactive oxygen species, and reduced levels of glutathione and glutathione peroxidase 4. The vast emerging literature on ferroptosis has shown that numerous diseases, such as cancers, neurodegeneration, and autoimmune diseases, are associated with ferroptosis. Meanwhile, recent studies have confirmed the relationship between ferroptosis and eye diseases including keratopathy, cataract, glaucoma, retinal ischemia-reperfusion injury, age-related macular degeneration, retinitis pigmentosa, diabetic retinopathy, and retinoblastoma, indicating the critical role of ferroptosis in ocular diseases. In this article, we introduce the primary signaling pathways of ferroptosis and review current advances in research on ocular diseases involving iron overload and ferroptosis. Furthermore, several unanswered questions in the area are raised. Addressing these unanswered questions promises to provide new insights into preventing, controlling, and treating not only ocular diseases but also a variety of other diseases in the near future.

The pathophysiological mechanisms underlying diabetic retinopathy

Diabetic retinopathy (DR) is the most common complication of diabetes mellitus (DM), which can lead to visual impairment and even blindness in severe cases. DR is generally considered to be a microvascular disease but its pathogenesis is still unclear. A large body of evidence shows that the development of DR is not determined by a single factor but rather by multiple related mechanisms that lead to different degrees of retinal damage in DR patients. Therefore, this article briefly reviews the pathophysiological changes in DR, and discusses the occurrence and development of DR resulting from different factors such as oxidative stress, inflammation, neovascularization, neurodegeneration, the neurovascular unit, and gut microbiota, to provide a theoretical reference for the development of new DR treatment strategies.

Nutritional strategies to alleviate oxidative stress in sows

The performance of high-yielding sows is directly related to the productivity of pig farming. Fetal development mainly occurs during the last month of pregnancy, and the aggressive metabolic burden of sows during this stage eventually leads to systemic oxidative stress. When affected by oxidative stress, sows exhibit adverse symptoms such as reduced feed intake, hindered fetal development, and even abortion. In addition, milk synthesis during the lactation period causes a severe metabolic burden. The biological response to oxidative stress during this period is associated with a decrease in milk production, which further affects the growth of piglets. Understanding the nutritional strategies to alleviate oxidative stress in sows is crucial to maintain their reproduction and lactation performance. Recently, advances have been made in the field of nutrition to relieve oxidative stress in sows during late pregnancy and lactation. This review highlights the nutritional strategies to relieve oxidative stress in sows reported within the last 20 years.

Molecular Mechanisms of Iron Mediated Programmed Cell Death and Its Roles in Eye Diseases

Ferroptosis, a newly identified, iron-dependent type of programmed cell death, is active in several diseases, such as heart disease, brain damage, and cancer. Its main characteristics commonly involve excess iron accumulation, elevated lipid peroxides and reactive oxygen species, and reduced levels of glutathione and glutathione peroxidase 4 levels. The effects of ferroptosis in eye diseases cannot be underestimated, with ferroptosis becoming a research target in ocular disorders and emerging evidence from a series of in vivo and in vitro researches into ferroptosis revealing its role in eye conditions. However, no report provides comprehensive information on the pathophysiology of ferroptosis in eye diseases and its possible treatments. In the current review, we present an up-to-date overview of ferroptosis biology and its involvement in the pathological processes of ocular diseases. Furthermore, we pose several outstanding questions and areas for future research in this topic. We deem ferroptosis-associated cell death a pivotal new field of scientific study in ocular diseases and consider it a new therapeutic target in the treatment of some eye disorders.

C1q/tumor necrosis factor-related protein-3 (CTRP3) activated by forkhead box O4 (FOXO4) down-regulation protects retinal pericytes against high glucose-induced oxidative damage through nuclear factor erythroid 2-related factor 2 (Nrf2)/Nuclear factor-kappaB (NF-κB) signaling

Diabetic retinopathy (DR) remains a major cause of blindness among diabetes mellitus patients. C1q/tumor necrosis factor-related protein-3 (CTRP3) is a novel adipokine which is associated with multiple types of metabolism. Nevertheless, little is known about the role of CTRP3 in high glucose (HG)-induced human retinal pericytes (HRPs). This study set out to assess the influence of CTRP3 on HG-induced HRPs and elucidate the latent regulatory mechanism. RT-qPCR and Western blot were to analyze CTRP3 and forkhead box O4 (FOXO4) expression. Western blot was also utilized to detect the protein levels of apoptosis-related factors and nuclear factor erythroid 2-related factor 2 (Nrf2)/Nuclear factor-kappaB (NF-κB) signaling-related factors. CCK-8 was to measure cell proliferation while TUNEL assay was to estimate cell apoptosis. Levels of oxidative stress biomarkers including manganese (MnSOD), catalase (CAT) and malonedialdehyde (MDA) were evaluated by the corresponding kits. JASPAR database, ChIP and luciferase reporter assay were to verify the interaction between FOXO4 and CTRP3 promoter. The experimental results uncovered that CTRP3 expression was decreased in HG-stimulated HRPs. Moreover, CTRP3 overexpression strengthened the viability while abrogated the apoptosis and oxidative stress of HG-induced HRPs. Furthermore. FOXO4 was up-regulated in HG-induced HRPs. Besides, FOXO4 bond to CTRP3 promoter and inhibited CTRP3 transcription to modulate the Nrf2/NF-κB signaling pathway. FOXO4 up-regulation reversed the influence of CTRP3 elevation on the proliferation, apoptosis and oxidative stress of HG-induced HRPs. To be summarized, CTRP3 negatively modulated by FOXO4 prevented HG-induced oxidative damage in DR via modulation of Nrf2/NF-κB signaling.

Effect of tacrolimus on the expression of Park7 in glomerular podocytes injured by puromycin aminonucleoside

OBJECTIVES

To study the effect of puromycin aminonucleoside (PAN) on the apoptosis of mouse podocyte clone 5 (MPC-5) and the expression of recombinant human Parkinson's disease 7 (Park7) and to study the protective mechanism of tacrolimus (FK506) against MPC-5 injury.

METHODS

MPC-5 cells were cultured in vitro and then divided into three groups: blank control (control), PAN, and FK506. The cells in the PAN group were added with PAN (with a concentration of 50 mg/L) to establish a model of MPC-5 injury, and those in the FK506 group were added with PAN (with a concentration of 50 mg/L) and FK506 (with a concentration of 5 mg/L). An inverted microscope was used to observe the morphology and structure of MPC-5 cells at 12, 24, and 48 hours after treatment. Flow cytometry was used to measure cell apoptosis rate. Quantitative real-time PCR was used to measure the mRNA expression of Park7. Western blot and immunofluorescent staining were used to measure the protein expression of Park7.

RESULTS

The control group had a large number of foot processes of the cell body at all time points, with tight connections between cells and a normal morphology. Compared with the control group, the PAN group had a significantly smaller cell volume at all time points, with loose connections between cells and the presence of ruptured cells. Compared with the PAN group, the FK506 group had an increased cell volume at all time points, with tighter connections between cells and a better morphology. The PAN group had a significantly higher apoptosis rate than the control group at all time points. Compared with the PAN group, the FK506 group had a significant reduction in the apoptosis rate at all time points (P<0.01). The PAN group had a significantly higher mRNA expression level of Park7 than the control group at all time points. Compared with the PAN group, the FK506 group had a significant reduction in the mRNA expression level of Park7 at all time points (P<0.01). Western blot showed that the PAN group had a significantly higher protein expression level of Park7 than the control group at all time points. Compared with the PAN group, the FK506 group had a significant reduction in the protein expression level of Park7 at all time points (P<0.01). Immunofluorescent staining showed that in the PAN group, there was a significantly lower expression of Park7 protein in cell membrane and cytoplasm, with a dense cluster distribution and increased fluorescence intensity. Compared with the PAN group, the FK506 group had a significant improvement in the distribution of Park7 protein.

CONCLUSIONS

PAN can act on MPC-5 cells and cause morphological and structural damage and apoptosis of MPC-5 cells, as well as upregulated mRNA and protein expression of Park7. FK506 can downregulate the mRNA and protein expression of Park7 in the model of MPC-5 injury, maintain cellular homeostasis, reduce proteinuria, and delay glomerulosclerosis.

PARK7 Protects Against Chronic Kidney Injury and Renal Fibrosis by Inducing SOD2 to Reduce Oxidative Stress

Renal fibrosis is the final common pathway to chronic kidney diseases regardless of etiology. Parkinson disease protein 7 (PARK7) is a multifunctional protein involved in various cellular processes, but its pathophysiological role in kidneys remain largely unknown. Here, we have determined the role of PARK7 in renal fibrosis and have further elucidated the underlying mechanisms by using the in vivo mouse model of unilateral ureteric obstruction (UUO) and the in vitro model of transforming growth factor-b (TGFB1) treatment of cultured kidney proximal tubular cells. PARK7 decreased markedly in atrophic kidney tubules in UUO mice, and Park7 deficiency aggravated UUO-induced renal fibrosis, tubular cell apoptosis, ROS production and inflammation. In vitro, TGFB1 treatment induced fibrotic changes in renal tubular cells, which was accompanied by alterations of PARK7. Park7 knockdown exacerbated TGFB1-induced fibrotic changes, cell apoptosis and ROS production, whereas Park7 overexpression or treatment with ND-13 (a PARK7-derived peptide) attenuated these TGFB1-induced changes. Mechanistically, PARK7 translocated into the nucleus of renal tubular cells following TGFB1 treatment or UUO, where it induced the expression of SOD2, an antioxidant enzyme. Taken together, these results indicate that PARK7 protects against chronic kidney injury and renal fibrosis by inducing SOD2 to reduce oxidative stress in tubular cells.

Ischemic Postconditioning-Mediated DJ-1 Activation Mitigate Intestinal Mucosa Injury Induced by Myocardial Ischemia Reperfusion in Rats Through Keap1/Nrf2 Pathway

Intestinal mucosal barrier dysfunction induced by myocardial ischemia reperfusion (IR) injury often leads to adverse cardiovascular outcomes after myocardial infarction. Early detection and prevention of remote intestinal injury following myocardial IR may help to estimate and improve prognosis after acute myocardial infarction (AMI). This study investigated the protective effect of myocardial ischemic postconditioning (IPo) on intestinal barrier injury induced by myocardial IR and the underlying cellular signaling mechanisms with a focus on the DJ-1. Adult SD rats were subjected to unilateral myocardial IR with or without ischemic postconditioning. After 30 min of ischemia and 120 min of reperfusion, heart tissue, intestine, and blood were collected for subsequent examination. The outcome measures were (i) intestinal histopathology, (ii) intestinal barrier function and inflammatory responses, (iii) apoptosis and oxidative stress, and (iv) cellular signaling changes. IPo significantly attenuated intestinal injury induced by myocardial IR. Furthermore, IPo significantly increased DJ-1, nuclear Nrf2, NQO1, and HO-1 expression in the intestine and inhibited IR-induced apoptosis and oxidative stress. The protective effect of IPo was abolished by the knockdown of DJ-1. Conversely, the overexpression of DJ-1 provided a protective effect similar to that of IPo. Our data indicate that IPo protects the intestine against myocardial IR, which is likely mediated by the upregulation of DJ-1/Nrf2 pathway.

Endothelium-dependent remote signaling in ischemia and reperfusion: Alterations in the cardiometabolic continuum

Intact endothelial function plays a fundamental role for the maintenance of cardiovascular (CV) health. The endothelium is also involved in remote signaling pathway-mediated protection against ischemia/reperfusion (I/R) injury. However, the transfer of these protective signals into clinical practice has been hampered by the complex metabolic alterations frequently observed in the cardiometabolic continuum, which affect redox balance and inflammatory pathways. Despite recent advances in determining the distinct roles of hyperglycemia, insulin resistance (InR), hyperinsulinemia, and ultimately diabetes mellitus (DM), which define the cardiometabolic continuum, our understanding of how these conditions modulate endothelial signaling remains challenging. It is widely accepted that endothelial cells (ECs) undergo functional changes within the cardiometabolic continuum. Beyond vascular tone and platelet-endothelium interaction, endothelial dysfunction may have profound negative effects on outcome during I/R. In this review, we summarize the current knowledge of the influence of hyperglycemia, InR, hyperinsulinemia, and DM on endothelial function and redox balance, their influence on remote protective signaling pathways, and their impact on potential therapeutic strategies to optimize protective heterocellular signaling.

Effects of neutron radiation on Nrf2-regulated antioxidant defense systems in rat lens

Accumulating evidence suggests that ionizing radiation (IR)-induced cataract may be associated with oxidative stress. Nuclear factor erythroid 2-related factor 2 (Nrf2) serves as a master regulator of the antioxidant defense system against oxidative stress. The present study aimed to investigate the effects of different doses of neutron radiation on the Nrf2-reegulated antioxidant defense system in rat lens and assess the status of oxidative stress. A total of 24 SD rats were randomly divided into the following four groups: i) Control group; iis) 0.4 Sv group; iii) 1.2 Sv group; and iv) 3.6 Sv group. The rats were sacrificed 7 days after radiation and lenses were dissected for histological, biochemical (malondialdehyde, glutathione and superoxide dismutase) and western blot (Nrf2, glutamate-cysteine ligase catalytic subunit and heme oxygenase 1) analyses. The morphological features of the lenses remained intact in the 0.4 Sv, 1.2 Sv and control groups, whilst the lenses in the 3.6 Sv group exhibited injuries. Results from the TUNEL assay demonstrated apparent apoptosis in lens epithelial cells following 3.6 Sv neutron radiation whereas sparse apoptosis was observed following 0.4 Sv and 1.2 Sv radiation. Malondialdehyde levels were reduced in the 0.4 Sv and 1.2 Sv groups but increased in the 3.6 Sv group, compared with those in the control group. Conversely, glutathione expression and the activity of superoxide dismutase were higher in the 0.4 Sv and 1.2 Sv groups, but lower in the 3.6 Sv group, compared with those in the control group. In addition, the total and nuclear protein levels of Nrf2 were increased following neutron radiation compared with those in the control group, though the Nrf2 protein levels decreased in the 3.6 Sv group compared with those in the 1.2 Sv group. The levels of glutamate-cysteine ligase catalytic subunit and heme oxygenase 1, downstream antioxidant enzymes of Nrf2, demonstrated the same profile as that in Nrf2. Taken together, the results of the present study suggest that neutron radiation affects Nrf2-regulated antioxidant systems in a two-stage process. Namely, the induction phase for low-dose radiation and regression phase for high-dose radiation. Therefore, it was hypothesized that activation and enhancement of the Nrf2-regulated antioxidant system may be useful in preventing or delaying IR-induced cataract, which may be extended even for other diseases associated with oxidative stress.

Sod2 and catalase improve pathological conditions of intervertebral disc degeneration by modifying human adipose-derived mesenchymal stem cells

OBJECTIVE

To investigate if the modification of human adipose-derived mesenchymal stem cells (hADSCs) by the antioxidants superoxide dismutase 2 (Sod2) and catalase (Cat) can attenuate the pathological conditions of intervertebral disc degeneration (IVD).

METHODS

In vitro, MTT assay and qRT-PCR was used to detect cell proliferation and gene expressions in hADSCs transduced with Ad-null (an adenovirus vector containing no transgene expression cassette), Ad-Sod2 (recombinant adenovirus Sod2) and Ad-Cat. IVD mouse models were generated by needle puncture and treated with hADSCs with/without Ad-null/Ad-Sod2/Ad-Cat. X-ray evaluation, magnetic resonance imaging (MRI) analysis, histological analysis, immunohistochemistry, Western blots, ELISAs and qRT-PCR were performed.

RESULTS

hADSCs transduced with Ad-Sod2 and Ad-Cat showed enhanced cell proliferation with the upregulation of SOX9, ACAN, and COL2. In vivo, IVD mice injected with hADSCs showed increased disc height index, MRI index and mean T2 intensities, as well as the attenuated histologic grading of the annulus fibrosus (AF) and NP accompanied by the upregulation of GAG and COL2, which were further improved in the Ad-Sod2 hADSC + IVD and Ad-Cat hADSC + IVD groups. Furthermore, the increased expression of IL-1β, IL-6 and TNF-α was reduced in IVD mice injected with hADSCs. Compared with the hADSC + IVD group, the Ad-Sod2 hADSC/Ad-Cat hADSC + IVD groups had lower expression of pro-inflammatory factors.

CONCLUSION

Modification of hADSCs by the antioxidants Sod2 and Cat improved the pathological condition of intervertebral disc tissues with increased GAG and COL2 expression, as well as reduced inflammation, thereby demonstrating a therapeutic effect in IVD.

The role of short-chain fatty acids in intestinal barrier function, inflammation, oxidative stress, and colonic carcinogenesis

Short-chain fatty acids (SCFAs), mainly including acetate, propionate, and butyrate, are metabolites produced during the bacterial fermentation of dietary fiber in the intestinal tract. They are believed to be essential factors affecting host health. Most in vitro and ex vivo studies have shown that SCFAs affect the regulation of inflammation, carcinogenesis, intestinal barrier function, and oxidative stress, but convincing evidence in humans is still lacking. Two major SCFA signaling mechanisms have been identified: promotion of histone acetylation and activation of G-protein-coupled receptors. In this review, we introduce the production and metabolic characteristics of SCFAs, summarize the potential effects of SCFAs on the four aspects mentioned above and the possible mechanisms. SCFAs have been reported to exert a wide spectrum of positive effects and have a high potential for therapeutic use in human-related diseases.

Quercetin protects against diabetic retinopathy in rats by inducing heme oxygenase-1 expression

Quercetin is a widely-occurring flavonoid that protects against cancer, and improves memory and cardiovascular functions. However, whether quercetin exhibits therapeutic effects in diabetic retinopathy remains unclear. In this study, we established a rat model of streptozocin-induced diabetic retinopathy. Seventy-two hours later, the rats were intraperitoneally administered 150 mg/kg quercetin for 16 successive weeks. Quercetin markedly increased the thickness of the retinal cell layer, increased the number of ganglion cells, and decreased the overexpression of the pro-inflammatory factors interleukin-1β, interleukin-18, interleukin-6 and tumor necrosis factor-α in the retinal tissue as well as the overexpression of high mobility group box-1 and the overactivation of the NLRP3 inflammasome. Furthermore, quercetin inhibited the overexpression of TLR4 and NF-κBp65, reduced the expression of the pro-angiogenic vascular endothelial growth factor and soluble intercellular adhesion molecule-1, and upregulated the neurotrophins brain-derived neurotrophic factor and nerve growth factor. Intraperitoneal injection of the heme oxygenase-1 inhibitor zinc protoporphyrin blocked the protective effect of quercetin. These findings suggest that quercetin exerts therapeutic effects in diabetic retinopathy possibly by inducing heme oxygenase-1 expression. This study was approved by the Animal Ethics Committee of China Medical University, China (approval No. 2016PS229K) on April 8, 2016.

Intravitreal conbercept improves outcome of proliferative diabetic retinopathy through inhibiting inflammation and oxidative stress

Conbercept is a newly-developed anti-vascular endothelial growth factor (VEGF) drug. This study aimed to evaluate the effects of conbercept on inflammation and oxidative response in proliferative diabetic retinopathy (PDR). Morphology changes in retinal microvasculature of PDR patients were determined by optical coherence tomographic angiography (OCTA). The mice were injected with streptozocin (STZ) for 20 weeks to induced PDR, then the changes in inflammatory factors, oxidative response and histological analysis were examined with Elisa assay, real time-PCR and commercial kits analysis. Conbercept treatment significantly alleviated the retinal pathological changes and significantly reduced intercellular cell adhesion molecule-1 (ICAM-1), macrophage inflammatory protein-1 (MIP-1), IL-1β, IL-6 and TNF-α protein levels but not prostaglandin E1 (PGE1), prostaglandin E2 (PGE2) and prostaglandin F2a (PGF2a) levels, all of which were remarkably elevated in aqueous fluid of PDR patients compared with non-PDR subjects. Meanwhile the inhibitory effects of conbercept on these inflammatory factors were proved by RT-PCR assays in mice experiments. And the inflammatory signal such as p-IKBα and p-p65 was correspondingly inhibited by conbercept in STZ-treated mice. Conbercept treatment significantly elevated the aqueous glutathione level of PDR patients and inhibited NOX-1, NOX-4 and ph22phox mRNA expressions and ROS production of PDR mice. Ki67 immunofluorescence staining showed that conbercept inhibited endothelial cell proliferation in retina of PDR mice. In conclusion, conbercept significantly inhibited the angiogenesis, inflammation and oxidative response in PDR mice, and these findings further reveals the molecular mechanisms of conbercept in treating PDR.

Astaxanthin Protects Retinal Photoreceptor Cells against High Glucose-Induced Oxidative Stress by Induction of Antioxidant Enzymes via the PI3K/Akt/Nrf2 Pathway

Diabetic retinopathy (DR) is a major microvascular complication that can lead to severe visual impairment in patients with diabetes. The elevated oxidative stress and increased reactive oxygen species (ROS) production induced by hyperglycemia have been reported to play an important role in the complex pathogenesis of DR. Astaxanthin (AST), a natural carotenoid derivative, has been recently recognized as a strong free radical scavenger and might, therefore, be beneficial in different diseases, including DR. In this study, we evaluated the potential role of AST as an antioxidative and antiapoptotic agent in protecting retinal cells and also investigated the involvement of the PI3K/Akt/Nrf2 pathway in AST-mediated effects. We treated high glucose-cultured mouse photoreceptor cells (661W) with different concentrations of AST and analyzed ROS production and cell apoptosis in the different regimens. Moreover, we also analyzed the expression of PI3K, Akt, Nrf2, and Phase II enzymes after AST treatment. Our results showed that AST dose-dependently reduced ROS production and attenuated 661W cell apoptosis in a high glucose environment. Importantly, its protective effect was abolished by treatment with PI3K or Nrf2 inhibitors, indicating the involvement of the PI3K/Akt/Nrf2 pathway. These results suggest AST as a nutritional supplement that could benefit patients with DR.