Fibroblast growth factor (FGF21) protects mouse liver against D-galactose-induced oxidative stress and apoptosis via activating Nrf2 and PI3K/Akt pathways

Mitigation of gestational diabetes-induced endothelial dysfunction through FGF21-NRF2 pathway activation involving L-Cystine

Gestational diabetes mellitus (GDM) disrupts glucolipid metabolism, endangering maternal and fetal health. Despite limited research on its pathogenesis and treatments, we conducted a study using serum samples from GDM-diagnosed pregnant women. We performed metabolic sequencing to identify key small molecule metabolites and explored their molecular interactions with FGF21. We also investigated FGF21's impact on GDM using blood samples from affected women. Our analysis revealed a novel finding: elevated levels of L-Cystine in GDM patients. Furthermore, we observed a positive correlation between L-Cystine and FGF21 levels, and found that L-Cystine induces NRF2 expression via FGF21 for a period of 96 h. Under high glucose (HG) conditions, FGF21 upregulates NRF2 and downstream genes NQO1 and EPHX1 via AKT phosphorylation induced by activation of IRS1, enhancing endothelial function. Additionally, we confirmed that levels of FGF21, L-Cystine, and endothelial function at the third trimester were effectively enhanced through appropriate exercise and diet during pregnancy in GDM patients (GDM + ED). These findings suggest FGF21 as a potential therapeutic agent for GDM, particularly in protecting endothelial cells. Moreover, elevated L-Cystine via appropriate exercise and diet might be a potential strategy to enhance FGF21's efficacy.

Cow placenta extract ameliorates d-galactose-induced liver damage by regulating BAX/CASP3 and p53/p21/p16 pathways

ETHNOPHARMACOLOGICAL RELEVANCE

Placenta is a kind of traditional Chinese medicine, known as "Ziheche", which has the function of tonifying qi and blood, nourishing liver and kidney. Placenta extract (PE) has been used for delaying organismal aging and treating various liver diseases. Cow placenta is a rich natural resource with large mass. Its composition is similar to that of human placenta, but it has not been effectively utilized. However, little is known about the effect of CPE on the liver of aging mice.

AIM OF THE STUDY

The aim of this study is to explore the protective effect and mechanism of CPE on the liver of d-galactose (D-gal) induced aging mice.

MATERIALS AND METHODS

Statistical methods were used to calculate mouse body weight and liver index. Hematoxylin-eosin (H&E) and transmission electron microscopy (TEM) were used to detect the morphological structure of the liver. Automatic biochemical analyzer was used to measure serum biochemical indicators. Three special staining methods were used to observe hepatocytes apoptosis, senescence and proliferation respectively. Relative kits were used to detect oxidative, inflammatory, and aging markers in the liver. Finally, real-time quantitative polymerase chain reaction and western-blot were used to detect aging related signaling pathways.

RESULTS

CPE significantly improved the morphological damage and dysfunction of liver, restored the activities of liver enzymes in serum, and alleviated liver oxidative stress and inflammatory response in D-gal induced aging mice. Furthermore, CPE inhibited hepatocyte apoptosis and senescence, and promoted hepatocyte proliferation by regulating BAX/CASP3 and p53/p21/p16 signaling pathways, ultimately reduced the effects of aging on the liver.

CONCLUSION

CPE effectively ameliorated the impact of aging on the liver by inhibiting free radical production or scavenging excessive free radicals, and its mechanism is associated to the regulation of apoptosis and proliferation-related factors.

Geraniol attenuates oxidative stress and neuroinflammation-mediated cognitive impairment in D galactose-induced mouse aging model

D-galactose (D-gal) administration was proven to induce cognitive impairment and aging in rodents' models. Geraniol (GNL) belongs to the acyclic isoprenoid monoterpenes. GNL reduces inflammation by changing important signaling pathways and cytokines, and thus it is plausible to be used as a medicine for treating disorders linked to inflammation. Herein, we examined the therapeutic effects of GNL on D-gal-induced oxidative stress and neuroinflammation-mediated memory loss in mice. The study was conducted using six groups of mice (6 mice per group). The first group received normal saline, then D-gal (150 mg/wt) dissolved in normal saline solution (0.9%, w/v) was given orally for 9 weeks to the second group. In the III group, from the second week until the 10th week, mice were treated orally (without anesthesia) with D-gal (150 mg/kg body wt) and GNL weekly twice (40 mg/kg body wt) four hours later. Mice in Group IV were treated with GNL from the second week up until the end of the experiment. For comparison of young versus elderly mice, 4 month old (Group V) and 16-month-old (Group VI) control mice were used. We evaluated the changes in antioxidant levels, PI3K/Akt levels, and Nrf2 levels. We also examined how D-gal and GNL treated pathological aging changes. Administration of GNL induced a significant increase in spatial learning and memory with spontaneously altered behavior. Enhancing anti-oxidant and anti-inflammatory effects and activating PI3K/Akt were the mechanisms that mediated this effect. Further, GNL treatment upregulated Nrf2 and HO-1 to reduce oxidative stress and apoptosis. This was confirmed using 99mTc-HMPAO brain flow gamma bioassays. Thus, our data suggested GNL as a promising agent for treating neuroinflammation-induced cognitive impairment.

Ginseng-Sanqi-Chuanxiong (GSC) extracts attenuate d-galactose-induced vascular aging in mice via inhibition of endothelial progenitor cells senescence

Vascular aging is an independent risk factor for age-related diseases and a specific type of organic aging. Endothelial progenitor cells (EPCs), a type of bone marrow stem cell, has been linked to vascular aging. The purpose of this study is to investigate if Ginseng-Sanqi-Chuanxiong (GSC) extract, a traditional Chinese medicine, can delay aortic aging in mice by enhancing the performance and aging of EPCs in vivo and to analyze the potential mechanisms through a d-Galactose (D-gal)-induced vascular aging model in mice. Our study revealed that GSC extracts not only enhanced the aortic structure, endothelial function, oxidative stress levels, and aging in mice, but also enhanced the proliferation, migration, adhesion, and secretion of EPCs in vivo, while reducing the expression of p53, p21, and p16. To conclude, GSC can delay vascular senescence by enhancing the function and aging of EPCs, which could be linked to a decrease in p16 and p53/p21 signaling. Consequently, utilizing GSC extracts to enhance the function and senescence of autologous EPCs may present a novel avenue for enhancing autologous stem cells in alleviating senescence.

Grape seed-derived procyanidin inhibits glyphosate-induced hepatocyte ferroptosis via enhancing crosstalk between Nrf2 and FGF12

BACKGROUND

Glyphosate (GLY) exposure induces hepatocyte ferroptosis through overproduction of reactive oxygen species, regarded as an important contributor to liver damage. Grape seed-derived procyanidin (GSDP) has been reported to be an effective antioxidant, but whether and, if any, how GSDP can attenuate GLY-induced liver injury via inhibiting ferroptosis is unclear.

PURPOSE

The current study aimed to investigate the hepato-protective effects and possible mechanisms of GSDP.

METHODS

GLY-induced liver damage mice model was established to explore the hepatoprotective roles of GSPE in vivo. Subsequently, bioinformatics methodology was used to predict the key pathways and factors related to the action targets of GSPE against hepatocyte ferroptosis. Finally, we explored the roles of nuclear factor E2 related factor 2 (Nrf2) and fibroblast growth factor 21 (FGF21) in blunting GLY-induced liver damage via suppressing ferroptosis in vitro.

RESULTS

GSDP exerts hepato-protective effects in vivo and in vitro through reduced oxidative stress and inhibited ferroptosis, which was related to the activation of Nrf2. Bioinformatics analysis showed an interaction between Nrf2 and FGF21. Furthermore, Nrf2 inhibition reduced FGF21 expression in the mRNA and protein levels. Fgf21 knockdown suppressed Nrf2 expression level, but recombinant FGF21 protein increased Nrf2 expression and promoted Nrf2 translocation into nucleus, suggesting a crosstalk between Nrf2 and FGF21. Intriguingly, the decreased levels of Nrf2 and FGF21 compromised the protective roles of GSDP against GLY-induced hepatocyte ferroptosis.

CONCLUSION

These findings suggest that GSDP attenuates GLY-caused hepatocyte ferroptosis via enhancing the interplay between Nrf2 and FGF21. Thus, GSDP may be a promising natural compound to antagonize ferroptosis-related damage.

Endoplasmic reticulum stress inhibitor may substitute for sleeve gastrectomy to alleviate metabolic dysfunction-associated steatotic liver disease

BACKGROUND

Metabolic dysfunction-associated steatotic liver disease (MASLD) is becoming the most common form of chronic liver disease worldwide. We explored the potential mechanisms responsible for the protective role of sleeve gastrectomy (SG) on MASLD in a high-fat diet (HFD) rat model.

METHODS

Rats were fed with HFD for 12 weeks to generate MASLD model that were subjected to SG or sham surgery. The endoplasmic reticulum stress (ERS) inhibitor 4-phenylbutyric acid (4-PBA) was injected intraperitoneally every day for 4 weeks after surgery to identify the impact of ERS.

RESULTS

The MASLD rat model was generated successfully, as indicated by significant upregulation of metabolic parameters. Fibroblast growth factor 21 (FGF21) and ERS-related proteins were increased in HFD rats, while expression of fibroblast growth factor receptor 1 was decreased as expected. An HFD also induced swelling and blurring of the endoplasmic reticulum and mitochondria in hepatocytes, and the above transformation could be relieved by SG and 4-PBA. SG and an ERS inhibitor both inhibited MASLD, but their combined treatment had no additional benefit.

CONCLUSIONS

Dysfunction of the FGF21 signaling pathway and hepatic steatosis and inflammation could be induced by an HFD, potentially causing MASLD. Bariatric surgery and ERS inhibition could alleviate MASLD by relieving ERS-mediated impairment of FGF21 signal transduction. These findings provide a new insight into the use of ERS inhibitors to treat MASLD, especially in patients who prefer to avoid surgery.

Recent progress in understanding mitokines as diagnostic and therapeutic targets in hepatocellular carcinoma

Hepatocellular carcinoma (HCC) is one of the most prevalent tumors worldwide and the leading contributor to cancer-related deaths. The progression and metastasis of HCC are closely associated with altered mitochondrial metabolism, including mitochondrial stress response. Mitokines, soluble proteins produced and secreted in response to mitochondrial stress, play an essential immunomodulatory role. Immunotherapy has emerged as a crucial treatment option for HCC. However, a positive response to therapy is typically dependent on the interaction of tumor cells with immune regulation within the tumor microenvironment. Therefore, exploring the specific immunomodulatory mechanisms of mitokines in HCC is essential for improving the efficacy of immunotherapy. This study provides a comprehensive overview of the association between HCC and the immune microenvironment and highlights recent progress in understanding the involvement of mitochondrial function in preserving liver function. In addition, a systematic review of mitokines-mediated immunomodulation in HCC is presented. Finally, the potential diagnostic and therapeutic roles of mitokines in HCC are prospected and summarized. Recent progress in mitokine research represents a new prospect for mitochondrial therapy. Considering the potential of mitokines to regulate immune function, investigating them as a relevant molecular target holds great promise for the diagnosis and treatment of HCC.

Development of muscle weakness in a mouse model of critical illness: does fibroblast growth factor 21 play a role?

BACKGROUND

Critical illness is hallmarked by severe stress and organ damage. Fibroblast growth factor 21 (FGF21) has been shown to rise during critical illness. FGF21 is a pleiotropic hormone that mediates adaptive responses to tissue injury and repair in various chronic pathological conditions. Animal studies have suggested that the critical illness-induced rise in FGF21 may to a certain extent protect against acute lung, liver, kidney and brain injury. However, FGF21 has also been shown to mediate fasting-induced loss of muscle mass and force. Such loss of muscle mass and force is a frequent problem of critically ill patients, associated with adverse outcome. In the present study, we therefore investigated whether the critical illness-induced acute rise in FGF21 is muscle-protective or rather contributes to the pathophysiology of critical illness-induced muscle weakness.

METHODS

In a catheterised mouse model of critical illness induced by surgery and sepsis, we first assessed the effects of genetic FGF21 inactivation, and hence the inability to acutely increase FGF21, on survival, body weight, muscle wasting and weakness, and markers of muscle cellular stress and dysfunction in acute (30 h) and prolonged (5 days) critical illness. Secondly, we assessed whether any effects were mirrored by supplementing an FGF21 analogue (LY2405319) in prolonged critical illness.

RESULTS

FGF21 was not required for survival of sepsis. Genetic FGF21 inactivation aggravated the critical illness-induced body weight loss (p = 0.0003), loss of muscle force (p = 0.03) and shift to smaller myofibers. This was accompanied by a more pronounced rise in markers of endoplasmic reticulum stress in muscle, without effects on impairments in mitochondrial respiratory chain enzyme activities or autophagy activation. Supplementing critically ill mice with LY2405319 did not affect survival, muscle force or weight, or markers of muscle cellular stress/dysfunction.

CONCLUSIONS

Endogenous FGF21 is not required for sepsis survival, but may partially protect muscle force and may reduce cellular stress in muscle. Exogenous FGF21 supplementation failed to improve muscle force or cellular stress, not supporting the clinical applicability of FGF21 supplementation to protect against muscle weakness during critical illness.

Exerkines and redox homeostasis

Exercise physiology has gained increasing interest due to its wide effects to promote health. Recent years have seen a growth in this research field also due to the finding of several circulating factors that mediate the effects of exercise. These factors, termed exerkines, are metabolites, growth factors, and cytokines secreted by main metabolic organs during exercise to regulate exercise systemic and tissue-specific effects. The metabolic effects of exerkines have been broadly explored and entail a promising target to modulate beneficial effects of exercise in health and disease. However, exerkines also have broad effects to modulate redox signaling and homeostasis in several cellular processes to improve stress response. Since redox biology is central to exercise physiology, this review summarizes current evidence for the cross-talk between redox biology and exerkines actions. The role of exerkines in redox biology entails a response to oxidative stress-induced pathological cues to improve health outcomes and to modulate exercise adaptations that integrate redox signaling.

Fibroblast growth factor 21 inhibits vascular calcification by ameliorating oxidative stress of vascular smooth muscle cells

Vascular calcification is very common in clinical. Severe vascular calcification is related to the occurrence of adverse events. Oxidative stress (OS) plays a pathophysiological role in the formation of vascular calcification. Previous studies have demonstrated that fibroblast growth factor 21(FGF21) could inhibit vascular calcification both in vivo and in vitro. FGF21 has also been proved to promote the recovery of superoxide dismutase (SOD) and thereby alleviate OS. Thus, our assumption was that FGF21 inhibit vascular calcification partly by restoring the level of antioxidant SOD and reducing OS. In this study, we established the vascular calcification by 5/6 nephrectomy plus high phosphate diet chronic kidney disease (CKD) model. The results showed the receptor of FGF21, fibroblast growth factor receptor 1 (FGFR1) and βKlotho in the aorta increased in CKD group, and mainly located in the media of the artery. Ulteriorly, immunofluorescence (IF) and IHC staining showed that FGFR1 and βKlotho mainly existed in arterial vascular smooth muscle cells (VSMCs). When FGF21 was knock out, the calcification was more severe in FGF21 KO + CKD mice, compared to wild type (WT)+ CKD mice. The transcriptional level of vascular calcification-related genes was significantly higher in FGF21 KO mice than control group. The dihydroethidium (DHE) staining reactive oxygen species (ROS) level in the CKD group was higher compared to the control group, but lower in FGF21 KO + CKD group, and the transcriptional level of SOD1 and SOD2 in FGF21 KO + CKD group was significantly higher than that in CKD group. In conclusion, FGF21 could inhibit vascular calcification, partly by restoring the level of antioxidant SOD and reducing vascular oxidative stress. This study provides further evidence for FGF21 as a candidate drug for cardiovascular protective agents.

The potential function and clinical application of FGF21 in metabolic diseases

As an endocrine hormone, fibroblast growth factor 21 (FGF21) plays a crucial role in regulating lipid, glucose, and energy metabolism. Endogenous FGF21 is generated by multiple cell types but acts on restricted effector tissues, including the brain, adipose tissue, liver, heart, and skeletal muscle. Intervention with FGF21 in rodents or non-human primates has shown significant pharmacological effects on a range of metabolic dysfunctions, including weight loss and improvement of hyperglycemia, hyperlipidemia, insulin resistance, cardiovascular disease, and non-alcoholic fatty liver disease (NAFLD). Due to the poor pharmacokinetic and biophysical characteristics of native FGF21, long-acting FGF21 analogs and FGF21 receptor agonists have been developed for the treatment of metabolic dysfunction. Clinical trials of several FGF21-based drugs have been performed and shown good safety, tolerance, and efficacy. Here we review the actions of FGF21 and summarize the associated clinical trials in obesity, type 2 diabetes mellitus (T2DM), and NAFLD, to help understand and promote the development of efficient treatment for metabolic diseases via targeting FGF21.

Emerging roles of fibroblast growth factor 21 in critical disease

In spite of the great progress in the management of critical diseases in recent years, its associated prevalence and mortality of multiple organ failure still remain high. As an endocrine hormone, fibroblast growth factor 21 (FGF21) functions to maintain homeostasis in the whole body. Recent studies have proved that FGF21 has promising potential effects in critical diseases. FGF21 has also been found to have a close relationship with the progression of critical diseases and has a great predictive function for organ failure. The level of FGF21 was elevated in both mouse models and human patients with sepsis or other critical illnesses. Moreover, it is a promising biomarker and has certain therapeutic roles in some critical diseases. We focus on the emerging roles of FGF21 and its potential effects in critical diseases including acute lung injury/acute respiratory distress syndrome (ALI/ARDS), acute myocardial injury (AMI), acute kidney injury (AKI), sepsis, and liver failure in this review. FGF21 has high application value and is worth further studying. Focusing on FGF21 may provide a new perspective for the management of the critical diseases.

Antioxidant Capacity and Protective Effect of Cow Placenta Extract on D-Galactose-Induced Skin Aging in Mice

Placental extract has been used for skin care and delaying skin aging. Cow placenta is an abundant resource with a large mass, which has not been harnessed effectively. Cow placenta extract (CPE) has the functions of antioxidation, anti-inflammatory, promoting growth and development, and promoting hair growth. However, little is known about the effect of oral administration of cow placenta extract on skin conditions. Therefore, the present study aimed to investigate the antioxidant capacity of CPE in vitro and in vivo and its protective effect on d-galactose (D-gal) induced skin aging in mice. The results showed that CPE had strong free radical scavenging, reducing and metal chelating activities. CPE can increase the activity of catalase (CAT), glutathione peroxidase (GSH-Px), peroxidase (POD), superoxide dismutase (SOD), and the content of glutathione (GSH), decrease the content of malondialdehyde (MDA). Moreover, CPE can decrease the gene and protein expression of matrix metalloproteinase 1a (MMP-1a) and matrix metalloproteinase 3 (MMP-3) and increase the expression of transforming growth factor-β (TGF-β) and tissue inhibitor of metalloproteinase 1 (TIMP-1) of mouse skin. Histopathological analysis showed CPE reduced the collagen damage caused by D-gal, increased collagen synthesis and reduced its degradation to delay skin aging.

Anti-Aging Effect of Momordica charantia L. on d-Galactose-Induced Subacute Aging in Mice by Activating PI3K/AKT Signaling Pathway

Anti-aging is a challenging and necessary research topic. Momordica charantia L. is a common edible medicinal plant that has various pharmacological activities and is often employed in daily health care. However, its anti-aging effect on mice and the underlying mechanism thereof remain unclear. Our current study mainly focused on the effect of Momordica charantia L. on d-galactose-induced subacute aging in mice and explored the underlying mechanism. UHPLC-Q-Exactive Orbitrap MS was applied to qualitatively analyze the chemical components of Momordica charantia L. ethanol extract (MCE). A subacute aging mice model induced by d-galactose (d-gal) was established to investigate the anti-aging effect and potential mechanism of MCE. The learning and memory ability of aging mice was evaluated using behavioral tests. The biochemical parameters, including antioxidant enzyme activity and the accumulation of lipid peroxides in serum, were measured to explore the effect of MCE on the redox imbalance caused by aging. Pathological changes in the hippocampus were observed using hematoxylin and eosin (H&E) staining, and the levels of aging-related proteins in the PI3K/AKT signaling pathway were assessed using Western blotting. The experimental results demonstrated that a total of 14 triterpenoids were simultaneously identified in MCE. The behavioral assessments results showed that MCE can improve the learning and memory ability of subacute mice. The biochemical parameters determination results showed that MCE can improve the activity of antioxidant enzymes and decrease the accumulation of lipid peroxides in aging mice significantly. Furthermore, aging and injury in the hippocampus were ameliorated. Mechanistically, the results showed a significant upregulation in the protein expression of P-PI3K/PI3K and P-AKT/AKT (p < 0.01), as well as a significant reduction in cleaved caspase-3/caspase-3, Bax and P-mTOR/mTOR (p < 0.01). Our results confirm that MCE could restore the antioxidant status and improve cognitive impairment in aging mice, inhibit d-gal-induced apoptosis by regulating the PI3K/AKT signaling pathway, and rescue the impaired autophagy caused by mTOR overexpression, thereby exerting an anti-aging effect.

CRISPR-Cas9-based genome-wide screening identified novel targets for treating sorafenib-resistant hepatocellular carcinoma: a cross-talk between FGF21 and the NRF2 pathway

The treatment of hepatocellular carcinoma (HCC) has been dominated by multikinase inhibitors for more than a decade. However, drug resistance can severely restrict the efficacy of these drugs. Using CRISPR/CAS9 genome library screening, we evaluated Kelch-like ECH-associated protein 1 (KEAP1) as a key regulator of sorafenib's susceptibility in HCC. We also investigated whether KEAP1's knockdown can stabilize nuclear factor (erythroid-derived 2)-like 2 (NRF2) protein levels that led to sorafenib's resistance, including an NRF2 inhibitor that can synergize with sorafenib to abolish HCC's growth in vitro and in vivo. Furthermore, we clarified that fibroblast growth factor 21 (FGF21) is an important downstream regulator of NRF2 in HCC. Intriguingly, we observed that FGF21 bound to NRF2 through the C-terminus of FGF21, thereby stabilizing NRF2 by reducing its ubiquitination and generating a positive feedback loop in sorafenib-resistant HCC. These findings, therefore, propose that targeting FGF21 is a promising strategy to combat HCC sorafenib's resistance.

Fibroblast Growth Factor 21 Predicts Short-Term Prognosis in Patients With Acute Heart Failure: A Prospective Cohort Study

BACKGROUND

Recent studies of fibroblast growth factor 21 (FGF21), first recognized as a regulator of glucose and lipid metabolism, have found that the level of in serum FGF21 is associated with the prognosis of many cardiovascular diseases, but its relationship to acute heart failure (AHF) patients remains unknown. Our study aimed to investigate whether circulating FGF21 could predict the short-term prognosis of AHF patients.

METHODS

Four hundred and two AHF patients and 19 healthy controls were recruited into the prospective cohort study, and blood samples of participants were collected, in tubes without anticoagulant, within the first 24 h after hospital admission. Serum FGF21 levels were detected by enzyme-linked immunosorbent assay (ELISA). All patients were followed-up at least 6 months after discharge. The primary endpoint was all-cause death, and secondary endpoint was a composite endpoint of death and heart failure readmission. Mortality and composite end point events were analyzed using Kaplan-Meier curves. ROC curves compared the difference between the FGF21 and NT-proBNP in predicting 3- and 6-months mortality. Time-to-event data were evaluated using Kaplan-Meier estimation and Cox proportional hazards models.

RESULTS

In the present study, the serum FGF21 concentrations were significantly higher in the 402 AHF patients enrolled, compared with the 19 healthy controls (p < 0.001). The average age was 70 (±12) years, and 58% were males. Participants were divided into two groups according to the median FGF21 level (262 pg/ml): a high FGF21 group (n = 201, FGF21 ≥ 262 pg/ml) and low FGF21 group (n = 201, FGF21 <262 pg/ml). FGF21 was positively correlated with NT-proBNP, BUN, AST, creatinine and cholesterol, and negatively correlated with ALB and HDL. After a median follow-up of 193 days, the high FGF21 group had higher mortality and composite endpoint events compared with the low FGF21 group (HR: 3.91, 95% CI 2.21-6.92, p <0.001), even after adjusting for NT-proBNP (HR: 3.17, 95% CI 1.72-5.81, p < 0.001). ROC analysis shows that FGF21 was better than NT-proBNP in predicting death at both 3 (AUC, 0.77 vs. 0.63, p < 0.001) and 6 months (AUC, 0.78 vs. 0.66).

CONCLUSION

High baseline FGF21 levels are associated with adverse clinical outcomes in AHF patients. Serum FGF21 might be a potential predictive biomarker of AHF patients.

Brite Adipocyte FGF21 Attenuates Cardiac Ischemia/Reperfusion Injury in Rat Hearts by Modulating NRF2

Although the optimal therapy for myocardial infarction includes reperfusion to restore blood flow to the ischemic area, myocardial injury after ischemia/reperfusion usually leads to an inflammatory response, oxidative stress, and cardiomyocyte apoptosis. In this study, rat adipose-derived stem cells were differentiated into low-thermogenic beige adipocytes (LBACs) and high-thermogenic beige adipocytes (HBACs) to study the different cardioprotective effects of heterogeneous expression of brown adipocytes. We found that antioxidant and antiapoptotic factors in H9c2 cardiomyocytes were upregulated by high levels of secreted FGF21 in HBAC conditioned medium (HBAC-CM), whereas FGF21 in HBAC-CM did not affect antioxidative or antiapoptotic cell death in H9c2 cardiomyocytes with Nrf2 knockdown. These results show that NRF2 mediates antioxidative and antiapoptotic effects through the HBAC-secreted factor FGF21. Consistent with this finding, the expression of antioxidant and antiapoptotic genes was upregulated by highly secreted FGF21 after HBAC-CM treatment compared to LBAC-CM treatment in H9c2 cardiomyocytes via NRF2 activation. Furthermore, HBAC-CM significantly attenuated ischemic rat heart tissue injury via NRF2 activation. Based on these findings, we propose that HBAC-CM exerts beneficial effects in rat cardiac ischemia/reperfusion injury by modulating NRF2 and has potential as a promising therapeutic agent for myocardial infarction.

Activation of activator protein-1-fibroblast growth factor 21 signaling attenuates Cisplatin hepatotoxicity

Fibroblast growth factor (Fgf/FGF) 21, which plays important roles in sugar, lipid and energy metabolism, has been accepted as a mito-stress marker gene. We recently reported that FGF21 expression can be up-regulated via activation of aryl hydrocarbon receptor (AhR) or glucocorticoid receptor (GR) and that FGF21 plays important cytoprotective roles. Cisplatin (cis-diamminedichloroplatinum, CDDP) is a widely used chemotherapeutic drug. Numerous adverse effects including hepatotoxicity have been noted during CDDP therapy. It is known that CDDP can induce mitochondrial dysfunction. The studies were designed to determine the regulation of Fgf/FGF21 expression by CDDP, and to characterize the underlying mechanisms of its regulation, as well as to determine the impact of gain or loss of Fgf/FGF21 function on the progression of CDDP hepatotoxicity. Our results showed that CDDP and phorbol ester induced mRNA and protein expression of Fgf/FGF21 and β-Klotho, two essential components of Fgf21 signaling, in mouse livers and cultured mouse/human hepatocytes. Luciferase reporter assays and ChIP-qPCR assays demonstrated that the cJun-AP-1 activation is responsible for CDDP- and phorbol ester-induced Fgf/FGF21 expression. Such induction is abolished after cotreated with AP-1 inhibitor SR11302. In addition, CDDP produces more severe liver injury in Fgf21-null than wild-type mice. Pre-treatment of GR activator dexamethasone or AhR activator β-Naphthoflavone, both of which can induce Fgf21 expression, attenuated CDDP-induced hepatotoxicity in vivo and in vitro. In conclusion, Fgf/FGF21-β-Klotho signaling can be activated via AP-1 activation. Gain of Fgf/FGF21 function attenuates the progression of CDDP hepatotoxicity, which may be considered clinically to improve CDDP therapy.

Fibroblast Growth Factor 21 Augments Autophagy and Reduces Apoptosis in Damaged Liver to Improve Tissue Regeneration in Zebrafish

Regeneration of a part of the diseased liver after surgical resection is mainly achieved by the proliferation of the remaining healthy liver cells. However, in case of extreme loss of liver cells or in the final stages of chronic liver disease, most liver cells are depleted or lose their ability to proliferate. Therefore, to foster liver regeneration, it is of great clinical and scientific significance to improve the survival and proliferation ability of residual hepatocytes. In this study, we conducted experiments on a zebrafish model of targeted ablation of liver cells to clarify the role of fibroblast growth factor 21 (FGF21). We found that FGF21 increased the regeneration area of the damaged liver and improved the survival rate of damaged liver cells by inhibiting cell apoptosis and reducing oxidative stress. Our results also showed that administration of FGF21 upregulated autophagy, and the beneficial effects of FGF21 were reversed by the well-known autophagy inhibitor chloroquine (CQ), indicating that FGF21-activated autophagy played a central role in the treatment. We further showed that the enhancement of autophagy induced by FGF21 was due to the activation of the AMPK-mTOR signaling pathway. Taken together, these data provide new evidence that FGF21 is an effective autophagy regulator that can significantly improve the survival of damaged livers.

Fibroblast growth factor 21 attenuates iron overload-induced liver injury and fibrosis by inhibiting ferroptosis

Ferroptosis plays a role in several diseases such as iron overload-induced liver diseases. Manipulation of ferroptosis has been explored as a potential therapeutic strategy to treat related diseases. Numerous antioxidants have been identified to control ferroptosis but the cell-autonomous mechanisms responsible for regulating ferroptosis remain elusive. In the present study, we found that iron overload promoted ferroptosis in hepatocytes by excessively inducing HO-1 expression, which contributed to the progression of liver injury and fibrosis, accompanied by the upregulation of the FGF21 protein level in vitro and in vivo. Interestingly, both recombinant FGF21 and Fgf21 overexpression significantly protected against iron overload-induced hepatocytes mitochondria damage, liver injury and fibrosis by inhibiting ferroptosis. In contrast, the loss of FGF21 aggravated iron overload-induced ferroptosis. Notably, FGF21-induced HO-1 inhibition (via the promotion of HO-1 ubiquitination and degradation) and NRF2 activation provide a mechanistic explanation for this phenomenon. Taken together, we identified FGF21 as a novel ferroptosis suppressor. Thus, FGF21 activation may provide an effective strategy for the potential treatment of iron overload-induced ferroptosis-related diseases, such as hereditary haemochromatosis (HH).

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Iron overload robustly induces hepatic FGF21 expression both in vitro and in vivo.

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FGF21 suppresses iron overload-induced hepatocytes ferroptosis.

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Constitutive HO-1 activation contributes to iron overload-induced ferroptosis in hepatocytes.

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FGF21 protects hepatocytes from iron overload-induced ferroptosis by stimulating HO-1 ubiquitination and degradation.

The p53/p21/p16 and PI3K/Akt signaling pathways are involved in the ameliorative effects of maltol on D-galactose-induced liver and kidney aging and injury

Successive evidence has established that maltol, a flavor-enhancing agent, could provide resistance to oxidative stress-induced tissue injury in various animal models though its benefits for aging-induced liver and kidney injuries are still undetermined. In the present work, for demonstrating maltol's ameliorative effect and probable mechanism against aging-induced liver and kidney injuries, D-galactose (D-Gal)-induced animal in vivo and HEK293 cells in vitro models were established and results demonstrated that long-term D-Gal treatment increases the accumulation of advanced glycation end products (AGEs) in liver and kidney tissues, mitigates cell viability, and arrests the cycle. Interestingly, 4-weeks maltol treatment at 50 and 100 mg/kg activated aging-associated proteins including p53, p21, and p16 followed by inhibiting malondialdehyde (MDA)'s over-production and increasing the levels of antioxidant enzymes. Therefore, decreases in cytochrome P450 E1 (CYP2E1) and 4-hydroxydecene (4-HNE)'s immunofluorescence expression levels are confirmed. Furthermore, maltol improved oxidative stress injury by activating the phosphatidylinositol-3-kinase (PI3K)/protein kinase B (Akt) signaling pathway. In conclusion, the purpose of the present study was to estimate the mechanistic insights into maltol's role as an antioxidant in liver and kidney cell senescence and injury, which will reflect potential of therapeutic strategy for antiaging and aging-related disease treatment.

D-galactose-induced liver aging model: Its underlying mechanisms and potential therapeutic interventions

Aging is associated with a variety of morphological and functional changes in the liver. Oxidative stress and inflammation are now widely accepted as the main mechanisms involved in the aging process that may subsequently cause severe injury to mitochondrial DNA which leads to apoptosis. As aging may increase the risks for various liver diseases and plays as an adverse prognostic factor increasing the mortality rate, knowledge regarding the mechanisms of age-related liver susceptibility and the possible therapeutic interventions is imperative. Due to cost and time constraints, a mimetic aging model is generally preferred to naturally aged animals to study the underlying mechanisms of aging liver. The use of D-galactose in aging research is dated back to 1962 and has since been used widely. This review aims to comprehensively summarize the effects of D-galactose-induced aging on the liver and the underlying mechanisms involved. Its potential therapeutic interventions are also discussed. It is hoped that this invaluable information may facilitate researchers in choosing the appropriate aging model and provide a valuable platform for testing potential therapeutic strategies for the prevention and treatment of age-related liver diseases.

The Keap1-Nrf2 System: A Mediator between Oxidative Stress and Aging

Oxidative stress, a term that describes the imbalance between oxidants and antioxidants, leads to the disruption of redox signals and causes molecular damage. Increased oxidative stress from diverse sources has been implicated in most senescence-related diseases and in aging itself. The Kelch-like ECH-associated protein 1- (Keap1-) nuclear factor-erythroid 2-related factor 2 (Nrf2) system can be used to monitor oxidative stress; Keap1-Nrf2 is closely associated with aging and controls the transcription of multiple antioxidant enzymes. Simultaneously, Keap1-Nrf2 signaling is also modulated by a more complex regulatory network, including phosphoinositide 3-kinase (PI3K)/protein kinase B (Akt), protein kinase C, and mitogen-activated protein kinase. This review presents more information on aging-related molecular mechanisms involving Keap1-Nrf2. Furthermore, we highlight several major signals involved in Nrf2 unbinding from Keap1, including cysteine modification of Keap1 and phosphorylation of Nrf2, PI3K/Akt/glycogen synthase kinase 3β, sequestosome 1, Bach1, and c-Myc. Additionally, we discuss the direct interaction between Keap1-Nrf2 and the mammalian target of rapamycin pathway. In summary, we focus on recent progress in research on the Keap1-Nrf2 system involving oxidative stress and aging, providing an empirical basis for the development of antiaging drugs.

PBK/TOPK: A Therapeutic Target Worthy of Attention

Accumulating evidence supports the role of PDZ-binding kinase (PBK)/T-lymphokine-activated killer-cell-originated protein kinase (TOPK) in mitosis and cell-cycle progression of mitotically active cells, especially proliferative malignant cells. PBK/TOPK was confirmed to be associated with the development, progression, and metastasis of malignancies. Therefore, it is a potential therapeutic target in cancer therapy. Many studies have been conducted to explore the clinical applicability of potent PBK/TOPK inhibitors. However, PBK/TOPK has also been shown to be overexpressed in normal proliferative cells, including sperm and neural precursor cells in the subventricular zone of the adult brain, as well as under pathological conditions, such as ischemic tissues, including the heart, brain, and kidney, and plays important roles in their physiological functions, including proliferation and self-renewal. Thus, more research is warranted to further our understanding of PBK/TOPK inhibitors before we can consider their applicability in clinical practice. In this study, we first review the findings, general features, and signaling mechanisms involved in the regulation of mitosis and cell cycle. We then review the functions of PBK/TOPK in pathological conditions, including tumors and ischemic conditions in the heart, brain, and kidney. Finally, we summarize the advances in potent and selective inhibitors and describe the potential use of PBK/TOPK inhibitors in clinical settings.

Celastrol attenuates ischemia/reperfusion-mediated memory dysfunction by downregulating AK005401/MAP3K12

BACKGROUND

Oxidative stress induces mitochondrial dysfunction, causing memory loss. Long noncoding RNAs influence mitochondrial function and suppress oxidative stress by regulating target protein expression and gene transcription. Celastrol, a natural antioxidant extracted from Tripterygium wilfordii Hook F. ("Thunder of God Vine"), effectively alleviates oxidative stress-mediated tissue injury. In the present study, we examined the effects of celastrol on memory dysfunction induced by ischemia/reperfusion (I/R) and elucidated the mechanisms underlying these effects.

METHODS

C57BL/6 mice were used to mimic I/R using the bilateral common carotid clip reperfusion method, and a hippocampal cell line (HT-22) cells were used to establish a model of oxygen-glucose deprivation/reoxygenation (OGD/R). We observed changes in behavior and mitochondrial structure. Cell activity, cell respiration, and antioxidant capacity were measured. MAP3K12, p-JNK, p-c-Jun, p-Akt/Akt, PI3K, Bcl-2, and Bax expression were evaluated.

RESULTS

I/R or OGD/R significantly increased AK005401 and MAP3K12 expression, further attenuating PI3K/Akt activation, promoting reactive oxygen species generation and causing mitochondrial dysfunction and cell apoptosis, thereby resulting in memory dysfunction. Celastrol increased antioxidant capacity, inhibited cell apoptosis, and improved mitochondrial function, effectively improving learning and memory by downregulating AK005401 and MAP3K12 and activating PI3K/Akt.

CONCLUSIONS

The AK005401/MAP3K12 signaling pathway has an important role in I/R-mediated hippocampal injury, and celastrol can potentially reduce or possibly prevent I/R-induced neuronal injury by downregulating AK005401/MAP3K12 signaling.

Modulatory Effect of Myokines on Reactive Oxygen Species in Ischemia/Reperfusion

There is a growing body of evidence showing the importance of physical activity against acute ischemic events in various organs. Ischemia/reperfusion injury (I/R) is characterized by tissue damage as a result of restriction and subsequent restoration of blood supply to an organ. Oxidative stress due to increased reactive oxygen species formation and/or insufficient antioxidant defense is considered to play an important role in I/R. Physical activity not only decreases the general risk factors for ischemia but also confers direct anti-ischemic protection via myokine production. Myokines are skeletal muscle-derived cytokines, representing multifunctional communication channels between the contracting skeletal muscle and other organs through an endocrine manner. In this review, we discuss the most prominent members of the myokines (i.e., brain-derived neurotrophic factor (BDNF), cathepsin B, decorin, fibroblast growth factors-2 and -21, follistatin, follistatin-like, insulin-like growth factor-1; interleukin-6, interleukin-7, interleukin-15, irisin, leukemia inhibitory factor, meteorin-like, myonectin, musclin, myostatin, and osteoglycin) with a particular interest in their potential influence on reactive oxygen and nitrogen species formation or antioxidant capacity. A better understanding of the mechanism of action of myokines and particularly their participation in the regulation of oxidative stress may widen their possible therapeutic use and, thereby, may support the fight against I/R.

Activation of AK005401 aggravates acute ischemia/reperfusion mediated hippocampal injury by directly targeting YY1/FGF21

Ischemia exerts a negative impact on mitochondrial function, which ultimately results in neuronal damage via alterations in gene transcription and protein expression. Long non- coding RNAs (LncRNAs) play pivotal roles in the regulation of target protein expression and gene transcription. In the present study, we observed the effect of an unclassical LncRNA AK005401on ischemia/reperfusion (I/R) ischemia-mediated hippocampal injury and investigated the regulatory role of fibroblast growth factor 21 (FGF21) and Yin Yang 1 (YY1). C57Black/6 mice were subjected to I/R using the bilateral common carotid clip reperfusion method, and AK005401 siRNA oligos were administered via intracerebroventricular injection. HT22 cells were used to establish a model of oxygen-glucose deprivation/reoxygenation (OGD/R). We observed pathological morphology and mitochondrial structure. Neuronal apoptosis was evident. Cell activity, cell respiration, FGF21, YY1, and antioxidant capacity were evaluated. I/R or OGD/R significantly increased the expressions of AK005401and YY1 and decreased FGF21expression, which further attenuated the activation of PI3K/Akt, promoted reactive oxygen species (ROS) generation, and then caused mitochondria dysfunction and cell apoptosis, which were reversed by AK005401 siRNA oligos and were aggravated by overexpression of AK005401 and YY1. We conclude that AK005401/YY1/FGF21 signaling pathway has an important role in I/R-mediated hippocampal injury.

Lactobacillus fermentum JX306 Restrain D-galactose-induced Oxidative Stress of Mice through its Antioxidant Activity

Oxidative stress-induced series of related degenerative diseases have received widespread attention. To screen new lactic acid bacteria (LAB) strains to resist oxidative stress, traditional Chinese fermented vegetables were used as a resource library to screen of LAB. The Lactobacillus fermentum JX306 strain, which showed high scavenging activity of DPPH free radical and hydrogen radical, and a strong lipid peroxidation inhibition rate in vitro was selected. L. fermentum JX306 was also examined for its antioxidant capacity in D-galactose-induced aging mice. The results showed that L. fermentum JX306 could significantly decrease malondialdehyde (MDA) levels and improve the activity of glutathione peroxidase (GSH-Px), and total antioxygenic capacity (TOC) in the serum, kidney, and liver. Meanwhile, the strain could remarkably upregulate the transcriptional level of the antioxidant-related enzyme genes, such as peroxiredoxin1 (Prdx1), glutathione reductase (Gsr), glutathione peroxidase (Gpx1), and thioredoxin reductase (TR3) encoding genes in the liver. Besides, histopathological observation proves that this probiotic strain could effectively inhibit oxidative damage to the liver and kidney in aging mice. Therefore, this unique antioxidant strain may have a high application value in the functional food industry and medicine industry.

Berberine ameliorates renal injury in a rat model of D-galactose-induced aging through a PTEN/Akt-dependent mechanism

This study aimed to investigate the protective effects of berberine (BBR) against D-galactose (D-gal)-induced renal aging in rats, pointing to its ability to modulate phosphatase and tensin homolog deleted on chromosome ten (PTEN)/Akt signalling, and to attenuate oxidative stress, inflammation and apoptosis. Renal aging was induced by subcutaneous injection of D-gal for six consecutive weeks along with simultaneous oral administration of BBR and compared to control rats and rats received individual doses of either drug. BBR treatment significantly reduced the serum levels of urea and creatinine, retrieved the alterations in kidney histopathology, and restored redox balance evidenced by alleviations of the level of malondialdehyde, 8-hydroxy-2'-deoxyguanosine and activating heme oxygenase-1 enzyme. Moreover, it markedly reduced the serum levels of pro-inflammatory mediators, along with down-regulation of PTEN expression, enhanced Akt activity, as well as significantly higher immunostaining of the anti-apoptotic marker (Bcl-2). These findings hold a great promise for the use of BBR as a protecting agent against renal aging.

Aronia melanocarpa Prevents Alcohol-Induced Chronic Liver Injury via Regulation of Nrf2 Signaling in C57BL/6 Mice

Aronia melanocarpa (AM), which is rich in anthocyanins and procyanidins, has been reported to exert antioxidative and anti-inflammatory effects. This study aimed to systematically analyze the components of AM and explore its effects on alcohol-induced chronic liver injury in mice. A component analysis of AM revealed 17 types of fatty acids, 17 types of amino acids, 8 types of minerals, and 3 types of nucleotides. Chronic alcohol-induced liver injury was established in mice via gradient alcohol feeding over a period of 6 months, with test groups orally receiving AM in the last 6 weeks. AM administration yielded potential hepatoprotective effects by alleviating weight gain and changes in organ indexes, decreasing the ratio of alanine aminotransferase/aspartate aminotransferase, reducing lipid peroxidation, enhancing antioxidant activities, decreasing oxidation-related factor levels, and regulating inflammatory cytokine levels. Histological analyses suggest that AM treatment markedly prevented organ damage in alcohol-exposed mice. Furthermore, AM activated nuclear factor erythroid 2-like 2 (Nrf2) by downregulating the expression of Kelch-like ECH-associated protein 1, resulting in elevated downstream antioxidative enzyme levels. AM activated Nrf2 via modulation of the phosphatidylinositol-3-hydroxykinase/protein kinase B signaling pathway. Altogether, AM prevented alcohol-induced liver injury, potentially by suppressing oxidative stress via the Nrf2 signaling pathway.

The Role of Akt2 in the Protective Effect of Fenofibrate against Diabetic Nephropathy

Fenofibrate (FF) protects against diabetic nephropathy (DN) in type 1 diabetic (T1D) mice by upregulating the expression of fibroblast growth factor 21 (FGF21), leading to the activation of the Akt-mediated Nrf2 antioxidant pathways. Here, we examined which isoforms of Akt contribute to FF activation of FGF21-mediated renal protection by examining the phosphorylation and expression of three isoforms, Akt1, Akt2, and Akt3. T1D induced by a single intraperitoneal dose of streptozotocin (STZ) resulted in reduced phosphorylation of one isoform, Akt2, but FF treatment increased renal Akt2 phosphorylation in these and normal mice, suggesting a potential and specific role for renal Akt2 in FF protection against T1D. This was further confirmed using in vitro cultured HK-2 human kidney tubule cells exposed to high glucose (HG) with siRNA silencing of the Akt2 gene and STZ-induced diabetic Akt2-knockout mice with and without 3-month FF treatment. In normal HK-2 cells exposed to HG for 24 hours, FF completely prevented cell death, reduced total Akt expression and glycogen synthase kinase (GSK)-3β phosphorylation, increased nuclear accumulation of Fyn, and reduced nuclear Nrf2 levels. These positive effects of FF were partially abolished by silencing Akt2 expression. Similarly, FF abolished T1D-induced renal oxidative stress, inflammation, and renal dysfunction in wild-type mice, but was only partially effective in Akt2-KO mice. Furthermore, FF treatment stimulated phosphorylation of AMPKα, an important lipid metabolism mediator, which in parallel with Akt2 plays an important role in FF protection against HG-induced HK-2 cells oxidative stress and damage. These results suggest that FF protects against DN through FGF21 to activate both Akt2/GSK-3β/Fyn/Nrf2 antioxidants and the AMPK pathway. Therefore, FF could be repurposed for the prevention of DN in T1D patients.

Fibroblast growth factor 21 in non-alcoholic fatty liver disease

Non-alcoholic fatty liver disease (NAFLD) encompasses a spectrum of pathologies ranging from uncomplicated hepatic fat accumulation to a state of lobular inflammation and hepatocyte ballooning, known as non-alcoholic steatohepatitis (NASH). Currently, there are no reliable biomarkers or effective therapeutic options established for NAFLD. Nevertheless, there are several molecular targets in the pipeline, of which fibroblast growth factor 21 (FGF21) is one. FGF21 is secreted primarily from liver and has a plethora of metabolic functions. Pre-clinical and epidemiological studies indicate a relationship between circulating FGF21 levels and hepatic fat content in both mice and humans. Moreover, animal studies have clearly shown that aberrant FGF21 signalling is a key pathological step in the development and progression of NAFLD. A recent Phase II clinical trial demonstrated that administration of an FGF21 analogue significantly reduced hepatic fat in subjects with NASH. As such, FGF21 provides a novel target for future biomarker and therapeutic studies. This review appraises preclinical data to outline the current understanding of FGF21 function in both normal hepatic function and NAFLD. Epidemiological evidence is explored to delineate the relationship between circulating FGF21 levels and NAFLD in humans. Finally, we review the therapeutic effects of FGF21 in the treatment of NAFLD.

FGF21 augments autophagy in random-pattern skin flaps via AMPK signaling pathways and improves tissue survival

Random-pattern skin flap is commonly used for surgical tissue reconstruction due to its ease and lack of axial vascular limitation. However, ischemic necrosis is a common complication, especially in distal parts of skin flaps. Previous studies have shown that FGF21 can promote angiogenesis and protect against ischemic cardiovascular disease, but little is known about the effect of FGF21 on flap survival. In this study, using a rat model of random skin flaps, we found that the expression of FGF21 is significantly increased after establishment skin flaps, suggesting that FGF21 may exert a pivotal effect on flap survival. We conducted experiments to elucidate the role of FGF21 in this model. Our results showed that FGF21 directly increased the survival area of skin flaps, blood flow intensity, and mean blood vessel density through enhancing angiogenesis, inhibiting apoptosis, and reducing oxidative stress. Our studies also revealed that FGF21 administration leads to an upregulation of autophagy, and the beneficial effects of FGF21 were reversed by 3-methyladenine (3MA), which is a well-known inhibitor of autophagy, suggesting that autophagy plays a central role in FGF21’s therapeutic benefit on skin flap survival. In our mechanistic investigation, we found that FGF21-induced autophagy enhancement is mediated by the dephosphorylation and nuclear translocation of TFEB; this effect was due to activation of AMPK-FoxO3a-SPK2-CARM1 and AMPK-mTOR signaling pathways. Together, our data provides novel evidence that FGF21 is a potent modulator of autophagy capable of significantly increasing random skin flap viability, and thus may serve as a promising therapy for clinical use.

D-Galactose-induced accelerated aging model: an overview

To facilitate the process of aging healthily and prevent age-related health problems, efforts to properly understand aging mechanisms and develop effective and affordable anti-aging interventions are deemed necessary. Systemic administration of D-galactose has been established to artificially induce senescence in vitro and in vivo as well as for anti-aging therapeutic interventions studies. The aim of this article is to comprehensively discuss the use of D-galactose to generate a model of accelerated aging and its possible underlying mechanisms involved in different tissues/organs.

Maltol (3-Hydroxy-2-methyl-4-pyrone) Slows d-Galactose-Induced Brain Aging Process by Damping the Nrf2/HO-1-Mediated Oxidative Stress in Mice

Maltol, a maillard reaction product from ginseng (Panax ginseng C. A. Meyer), has been confirmed to inhibit oxidative stress in several animal models. Its beneficial effect on oxidative stress related brain aging is still unclear. In this study, the mouse model of d-galactose (d-Gal)-induced brain aging was employed to investigate the therapeutic effects and potential mechanisms of maltol. Maltol treatment significantly restored memory impairment in mice as determined by the Morris water maze tests. Long-term d-Gal treatment reduced expression of cholinergic regulators, i.e., the cholineacetyltransferase (ChAT) (0.456 ± 0.10 vs 0.211 ± 0.03 U/mg prot), the acetylcholinesterase (AChE) (36.4 ± 5.21 vs 66.5 ± 9.96 U/g). Maltol treatment prevented the reduction of ChAT and AChE in the hippocampus. Maltol decreased oxidative stress levels by reducing levels of reactive oxygen species (ROS) and malondialdehyde (MDA) production in the brain and by elevating antioxidative enzymes. Furthermore, maltol treatment minimized oxidative stress by increasing the phosphorylation levels of phosphatidylinositol-3-kinase (PI3K), protein kinase B (Akt), nuclear factor-erythroid 2-related factor 2 (Nrf2), and hemeoxygenase-1 (HO-1). The above results clearly indicate that supplementation of maltol diminishes d-Gal-induced behavioral dysfunction and neurological deficits via activation of the PI3K/Akt-mediated Nrf2/HO-1 signaling pathway in brain. Maltol might become a potential drug to slow the brain aging process and stimulate endogenous antioxidant defense capacity. This study provides the novel evidence that maltol may slow age-associated brain aging.

Leonurine ameliorates D-galactose-induced aging in mice through activation of the Nrf2 signalling pathway

Aging is a complex physiological phenomenon associated with oxidative stress damage. The objective of this study was to investigate the potential effects of leonurine on D-galactose-induced aging in mice and its possible mechanisms. In this study, we first tested the antioxidant activity of leonurine in vitro. A subcutaneous injection of D-galactose in mice for 8 weeks was used to establish the aging model to evaluate the protective effects of leonurine. The results showed that treatment with 150 mg·kg^-1 leonurine could improve the mental condition, organic index, and behavioural impairment; significantly increase the activities of antioxidative enzymes including SOD, CAT, and T-AOC; and ameliorate the advanced glycation end product (AGE) level and histopathological injury. Furthermore, the Western blotting data revealed that leonurine supplementation noticeably modulated the suppression of the Nrf2 pathway and upregulated the downstream expression of HO-1 and NOQ1 in aging mice. Additionally, leonurine treatment activated Nrf2 nuclear translocation in both aging mice and normal young mice, and the expression levels of Nrf2 in normal young mice was higher than those in naturally aging mice. In conclusion, our findings suggest that leonurine is a promising agent for attenuating the aging process, and the underlying molecular mechanisms depend on activating the Nrf2 pathway.

In vitro and in vivo evaluation of an exopolysaccharide produced by Lactobacillus helveticus KLDS1.8701 for the alleviative effect on oxidative stress

Correlations between oxidative stress and degenerative diseases have been gaining increasing attention. A number of studies affirm that exopolysaccharide (EPS) produced by lactic acid bacteria (LAB) can alleviate oxidative stress and further prevent the related diseases. In our previous study, Lactobacillus helveticus KLDS1.8701 has been shown to possess high antioxidant capacity in vitro. The aim of this study was to evaluate the ameliorative effects of EPS produced by L. helveticus KLDS1.8701 on oxidative stress. Firstly, EPS was isolated from the culture of L. helveticus KLDS1.8701 and purified using DEAE-Sepharose Fast Flow chromatography. Secondly, the antioxidant capacities of EPS fractions were evaluated using in vitro methods. Thirdly, an in vivo study was performed to investigate the possible protective effects of EPS on d-galactose (d-gal)-induced liver damage and gut microbiota disorder. In vitro antioxidant activity results suggested that EPS-1 exhibited strong scavenging properties on 2,2-diphenyl-1-picrylhydrazyl radical, superoxide radical, hydroxyl radical, and chelating activity on ferrous ion. In vivo, EPS-1 supplementation significantly attenuated oxidative status such as decreased organic index, liver injury and liver oxidative stress. EPS-1 supplementation shifted the gut microbiota composition to that of the control group. In addition, the analysis of Spearman's rank correlation suggested that the protective effects of EPS correlated with manipulating the gut microbiota composition in d-gal-induced mice. These results implied that EPS-1 supplementation could mitigate hepatic oxidative stress via manipulating the gut microbiota composition and be used as a potential candidate to attenuate oxidative damage.

Polysaccharide from Okra (Abelmoschus esculentus (L.) Moench) Improves Antioxidant Capacity via PI3K/AKT Pathways and Nrf2 Translocation in a Type 2 Diabetes Model

Polysaccharide extracted from okra (Abelmoschus esculentus (L.) Moench), a traditional functional food, is a biologically active substance reported to possess hypoglycemic and anti-oxidative qualities. However, it is unknown which polysaccharides play a role and have the potential mechanism. This present study is to assess the possible impacts of a novel polysaccharide isolated from okra (OP) on mice fed with a high-fat diet (HFD) combined with an intraperitoneal injection (i.p.) of 100 mg/kg streptozotocin (STZ) twice, to induce type 2 diabetes mellitus (T2DM). We found that an eight-week administration of OP at 200 or 400 mg/kg body weight significantly alleviated the symptoms, with elevations in blood glucose, triglyceride (TG), total cholesterol (TC) and low-density lipoprotein cholesterol (LDL-C), as well as reducing high-density lipoprotein cholesterol (HDL-C), body weight, food, and water consumption. The OP treatment increased the hepatic glycogen and decreased the mussy hepatic cords and liver fibrosis in the T2DM mice. The decreases of ROS and MDA and the increases of SOD, GSH-Px and CAT in liver were observed after administration of OP. OP alleviated the T2DM characteristics through the activation of the phosphoinositide 3-kinase (PI3K)/protein kinase B (AKT)/glycogen synthase kinase 3 beta (GSK3β) pathway, and enhanced the nuclear factor erythroid-2 (Nrf2) expression and promoted Nrf2-medicated heme oxygenase-1(HO-1) and superoxide dismutase 2 (SOD2) expression. OP also relieved mitochondrial dysfunction by inhibiting NOX2 activation. Taken together, these findings suggest that a polysaccharide isolated from okra exerts anti-T2DM effects partly by modulating oxidative stress through PI3K/AKT/GSK3β pathway-medicated Nrf2 transport. We have determined that a polysaccharide possesses hypoglycemic activity, as well as its underlying mechanism.

Flavonoid-Rich Ethanol Extract from the Leaves of Diospyros kaki Attenuates D-Galactose-Induced Oxidative Stress and Neuroinflammation-Mediated Brain Aging in Mice

Aging is a major factor that contributes to neurological impairment and neuropathological changes, such as inflammation, oxidative stress, neuronal apoptosis, and synaptic dysfunction. Flavonoids act as protective antioxidant and anti-inflammatory agents against various age-related neurodegenerative diseases. Here, we investigated the protective effect and mechanisms of the flavonoid-rich ethanol extract from the leaves of Diospyros kaki (FELDK) in the cortex and hippocampus of D-galactose- (gal-) aged mice. Our results showed that FELDK treatment restored memory impairment in mice as determined by the Y-maze and Morris water maze tests. FELDK decreased oxidative stress levels via inhibiting reactive oxygen species (ROS) and malondialdehyde (MDA) production and elevating antioxidative enzymes. FELDK also alleviated D-gal-induced neuroinflammation via suppressing the expression of advanced glycation end products (AGEs) and receptor for AGEs (RAGE) and activating microgliosis and astrocytosis, nuclear factor kappa B (NF-κB) nuclear translocation, and downstream inflammatory mediators. Moreover, FELDK inhibited the phosphatidylinositol 3-kinase (PI3K)/Akt and C-jun N-terminal kinase (JNK) apoptotic signaling pathways and ameliorated the impairment of synapse-related proteins. Hence, these results indicate that FELDK exerts neuroprotective effects on D-gal-induced brain aging. Thus, FELDK may be a potential therapeutic strategy for preventing and treating age-related neurodegenerative diseases such as Alzheimer's disease.

Increased fucoxanthin in Chaetoceros calcitrans extract exacerbates apoptosis in liver cancer cells via multiple targeted cellular pathways

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Both treatments inhibited cancer proliferation in a time and dose dependent manner.

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FxRF treatment were effective in inducing apoptosis in HepG2 cells than crude extract.

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Treatments stimulated regulation in cell signalling, apoptotic and antioxidant genes.

In this study, anti-proliferative effects of C. calcitrans extract and its fucoxanthin rich fraction (FxRF) were assessed on human liver HepG2 cancer cell line. Efficacy from each extract was determined by cytotoxicity assay, morphological observation, and cell cycle analysis. Mechanisms of action observed were evaluated using multiplex gene expression analysis. Results showed that CME and FxRF induced cytotoxicity to HepG2 cells in a dose and time-dependent manner. FxRF (IC₅₀: 18.89 μg.mL⁻¹) was found to be significantly more potent than CME (IC₅₀: 87.5 μg.mL⁻¹) (p < 0.05). Gene expression studies revealed that anti-proliferative effects in treated cells by C. calcitrans extracts were mediated partly through the modulation of numerous genes involved in cell signaling (AKT1, ERK1/2, JNK), apoptosis (BAX, BID, Bcl-2, APAF, CYCS) and oxidative stress (SOD1, SOD2, CAT). Overall, C. calcitrans extracts demonstrated effective intervention against HepG2 cancer cells where enhanced apoptotic activities were observed with increased fucoxanthin content.

Fibroblast growth factor 21 facilitates peripheral nerve regeneration through suppressing oxidative damage and autophagic cell death

Seeking for effective drugs which are beneficial to facilitating axonal regrowth and elongation after peripheral nerve injury (PNI) has gained extensive attention. Fibroblast growth factor 21 (FGF21) is a metabolic factor that regulates blood glucose and lipid homeostasis. However, there is little concern for the potential protective effect of FGF21 on nerve regeneration after PNI and revealing related molecular mechanisms. Here, we firstly found that exogenous FGF21 administration remarkably promoted functional and morphologic recovery in a rat model of sciatic crush injury, manifesting as persistently improved motor and sensory function, enhanced axonal remyelination and regrowth and accelerated Schwann cells (SCs) proliferation. Furthermore, local FGF21 application attenuated the excessive activation of oxidative stress, which was accompanied with the activation of nuclear factor erythroid‐2‐related factor 2 (Nrf‐2) transcription and extracellular regulated protein kinases (ERK) phosphorylation. We detected FGF21 also suppressed autophagic cell death in SCs. Additionally, treatment with the ERK inhibitor U0126 or autophagy inhibitor 3‐MA partially abolishes anti‐oxidant effect and reduces SCs death. Taken together, these results indicated that the role of FGF21 in remyelination and nerve regeneration after PNI was probably related to inhibit the excessive activation of ERK/Nrf‐2 signalling‐regulated oxidative stress and autophagy‐induced cell death. Overall, our work suggests that FGF21 administration may provide a new therapy for PNI.

Effect of FGF-21 on implant bone defects through hepatocyte growth factor (HGF)-mediated PI3K/AKT signaling pathway

Implant bone defects are the most common phenomenon in the processes of bone transplantation. Evidences have identified that fibroblast growth factor-21 (FGF-21) encourages osteogenesis for patients with implant bone defects. The purpose of this study was to investigate the role of FGF-21 and its potential mechanism in bone mesenchymal stem cells (BMSCs). RT-PCR, Western blotting, flow cytometry, immunofluorescence and immunohistochemistry assays were performed to analyze the role of FGF-21 and intracellular signaling pathways involved in BMSCs. It was shown that FGF-21 increased viability of BMSCs. Treatment with FGF-21 decreased the apoptosis of BMSCs by decreasing pro-apoptosis protein Caspase-3. Results indicated that FGF-21 (2 mg/kg) treatment up-regulated HGF, PI3K and AKT expression in BMSCs. In addition, the protective effects of FGF-21 on BMSCs were canceled by PI3K/AKT inhibitor in BMSCs. Results found that knockdown of HGF abolished FGF-21-decreased PI3K/AKT signal pathway. Furthermore, results demonstrated that FGF-21 presented beneficial effects for implant bone defects in rat model. In conclusion, these results indicate that FGF-21 can improve implant bone defects through HGF-mediated PI3K/AKT signaling pathway in BMSCs.

Lactic Acid Bacteria With Antioxidant Activities Alleviating Oxidized Oil Induced Hepatic Injury in Mice

In order to screening new Lactic acid bacteria (LAB) strains to alleviating liver injury induced by oxidized oil, we isolated and screened LAB from Chinese fermented foods. Lactobacillus plantarum AR113, Pediococcus pentosaceus AR243, and Lactobacillus plantarum AR501 showed higher scavenging activity of α, α-Diphenyl-β-Picrylhydrazyl (DPPH) free radical and hydrogen radical, stronger inhibition of lipid peroxidation, and better protective effect on yeast cells in vitro. In vivo, oral administration of L. plantarum AR501 improved the antioxidant status of injury mice induced by oxidized oil including decreasing lipid peroxidation, recovering activities of antioxidant enzymes. Meanwhile, the gene expression of Nuclear factor erythroid 2-related factor 2 (Nrf2) of L. plantarum AR501 group was markedly elevated, and several antioxidant genes such as glutathione S-transferase (GSTO1), heme oxygenase-1 (HO-1), Glutamate cysteine ligase (GCL), and NAD(P)H:quinone oxidoreductase-l (NQO1) were subsequently up regulated in mice liver. Therefore, L. plantarum AR501 could be considered as potential candidates for production of functional foods that can alleviate the oxidative damage induced by oxidized oil.

Neuronal SIRT1 regulates macronutrient-based diet selection through FGF21 and oxytocin signalling in mice

Diet affects health through ingested calories and macronutrients, and macronutrient balance affects health span. The mechanisms regulating macronutrient-based diet choices are poorly understood. Previous studies had shown that NAD-dependent deacetylase sirtuin-1 (SIRT1) in part influences the health-promoting effects of caloric restriction by boosting fat use in peripheral tissues. Here, we show that neuronal SIRT1 shifts diet choice from sucrose to fat in mice, matching the peripheral metabolic shift. SIRT1-mediated suppression of simple sugar preference requires oxytocin signalling, and SIRT1 in oxytocin neurons drives this effect. The hepatokine FGF21 acts as an endocrine signal to oxytocin neurons, promoting neuronal activation and Oxt transcription and suppressing the simple sugar preference. SIRT1 promotes FGF21 signalling in oxytocin neurons and stimulates Oxt transcription through NRF2. Thus, neuronal SIRT1 contributes to the homeostatic regulation of macronutrient-based diet selection in mice.

Protective effect of Anwulignan against D-galactose-induced hepatic injury through activating p38 MAPK-Nrf2-HO-1 pathway in mice

Background

Liver aging is a significant risk factor for chronic liver diseases. Oxidative stress has been considered as a conjoint pathological mechanism for the initiation and progression of liver aging. It has been reported that d-galactose (d-gal)-induced hepatic injury is an experimental model well established closely similar to morphological and functional features of liver aging. Schisandra sphenanthera Rehd. et Wils (S. sphenanthera, Schisandraceae), as a famous tradi-tional Chinese medicine, has been used for thousands of years in China to treat various disorders, including liver dysfunctions. This study was aimed to understand whether Anwulignan, one of the monomeric compounds in the lignans from S. sphenanthera, could improve the hepatic injury induced by d-gal in mice and to examine the possible mechanisms.

Methods

ICR mice were used to produce hepatic injury by 220 mg kg-1 d-gal subcutaneously once daily for 42 days. The effects of oral Anwulignan on liver index; serial AST and ALT levels; histological changes; SOD, GSH-Px, MDA, and 8-OHdG in the liver and peripheral blood; expression of p38 mitogen-activated protein kinase (MAPK), Nrf2, and HO-1 in the liver; and HepG2 cell viability, and decrease caspase-3 contents in liver were examined.

Results

Anwulignan could significantly increase the liver index, lower aspartate aminotransferase (AST) and alanine aminotransferase (ALT) levels in the peripheral blood, elevate superoxide dis-mutase (SOD) and glutathione peroxidase (GSH-Px) activities, and decrease malonaldehyde (MDA) and 8-hydroxy-2-deoxyguanosine (8-OHdG) contents in the peripheral blood and liver. Furthermore, Anwulignan could upregulate the expression of p38 mitogen-activated protein kinase (MAPK), Nrf2, and HO-1 in the liver, increase the HepG2 cell viability, and decrease caspase-3 contents in liver.

Conclusion

Anwulignan has protective effects against the hepatic injury induced by d-gal, which may be related to its antioxidant capacity through activating p38 MAPK-Nrf2-HO-1 pathway, increases the injured cell viability, and decreases the caspase-3 contents in liver.

FGF21 protects human umbilical vein endothelial cells against high glucose-induced apoptosis via PI3K/Akt/Fox3a signaling pathway

AIMS

Diabetic macroangiopathy is the main cause of morbidity and mortality in patients with diabetes. Endothelial cell injury is a pathological precondition for diabetic macroangiopathy. Fibroblast growth factor 21 (FGF21) is a key metabolic regulator which has recently been suggested to protect cardiac myocytes and vascular cells against oxidative stress-induced injury in vitro and vivo. In this study, we aimed to investigate the protective capacity of FGF21 in human umbilical vein endothelial cells (HUVECs) against high glucose (HG)-induced apoptosis via phosphatidylinositol-3-kinase/protein kinase B (PI3K/Akt)/FoxO3a pathway.

METHODS

The cell viability was examined by CCK-8 assay, Intracellular ROS levels were measured by the detection of the fluorescent product formed by the oxidation of DCFH-DA, Apoptosis was analyzed using Hoechst 33258 nuclear staining and Flow Cytometry Analysis (FCA), the expression of protein were detected by Western blot.

RESULTS

Results show that pretreating HUVECs with FGF21 before exposure to HG increases cell viability, while decreasing apoptosis and the generation of reactive oxygen species. Western blot analysis shows that HG reduces the phosphorylation of Akt and FoxO3a, and induces nuclear localization of FoxO3a. The effects were significantly reversed by FGF21 pre-treatment. Furthermore, the protective effects of FGF21 were prevented by PI3K/Akt inhibitor LY294002.

CONCLUSIONS

Our data demonstrates that FGF21 protects HUVECs from HG-induced oxidative stress and apoptosis via the activation of PI3K/Akt/FoxO3a signaling pathway.

Inhibiting the integrated stress response pathway prevents aberrant chondrocyte differentiation thereby alleviating chondrodysplasia

The integrated stress response (ISR) is activated by diverse forms of cellular stress, including endoplasmic reticulum (ER) stress, and is associated with diseases. However, the molecular mechanism(s) whereby the ISR impacts on differentiation is incompletely understood. Here, we exploited a mouse model of Metaphyseal Chondrodysplasia type Schmid (MCDS) to provide insight into the impact of the ISR on cell fate. We show the protein kinase RNA-like ER kinase (PERK) pathway that mediates preferential synthesis of ATF4 and CHOP, dominates in causing dysplasia by reverting chondrocyte differentiation via ATF4-directed transactivation of Sox9. Chondrocyte survival is enabled, cell autonomously, by CHOP and dual CHOP-ATF4 transactivation of Fgf21. Treatment of mutant mice with a chemical inhibitor of PERK signaling prevents the differentiation defects and ameliorates chondrodysplasia. By preventing aberrant differentiation, titrated inhibition of the ISR emerges as a rationale therapeutic strategy for stress-induced skeletal disorders.