Curcumin protects rats against gentamicin-induced nephrotoxicity by amelioration of oxidative stress, endoplasmic reticulum stress and apoptosis

CONTEXT

Gentamicin (GM) is an aminoglycoside antibiotic which is commonly used against Gram-negative bacterial infection; however, serious complications including nephrotoxicity could limit its clinical use.

OBJECTIVE

The present study examined the protective effects of curcumin (CUR) on endoplasmic reticulum (ER) stress-mediated apoptosis through its antioxidative property in GM-induced nephrotoxicity in rats.

MATERIALS AND METHODS

Male Sprague-Dawley rats (n = 3) were divided into six groups to receive normal saline (control), GM (100 mg/kg/day), co-treatment with GM and CUR (100, 200 and 300 mg/kg/day) and CUR (200 mg/kg/day) alone for 15 days by gavage feeding. Then, the renal function, kidney injury as well as oxidative stress, antioxidative markers and ER stress-mediated apoptosis were evaluated.

RESULTS

Pre-treatment of CUR rescued the nephrotoxicity in GM-treated rats. Several nephrotoxicity hallmarks were reversed in the CUR-pre-treatment group. At the dose of 200 mg/kg/day, it could significantly lower serum creatinine (from 0.95 to 0.50 mg/dL), blood urea nitrogen (from 35.00 to 23.50 mg/dL) and augmented creatinine clearance (from 0.83 to 1.71 mL/min). The normalized expression of oxidative stress marker, malondialdehyde was decreased (from 13.00 to 5.98) in line with the increase of antioxidant molecules including superoxide dismutase (from 5.59 to 14.24) and glutathione (from 5.22 to 12.53). Furthermore, the renal ER stress and apoptotic protein biomarkers were lowered in CUR treatment.

DISCUSSION AND CONCLUSIONS

Our findings pave the way for the application of CUR as a supplement in the prevention of nephrotoxicity and other kidney diseases in the future.

Integrated chemical profiling, network pharmacology and pharmacological evaluation to explore the potential mechanism of Xinbao pill against myocardial ischaemia-reperfusion injury

CONTEXT

Xinbao pill (XBW), a traditional Chinese herbal formula, is widely used in clinical treatment for cardiovascular diseases; however, the therapeutic effect of XBW on myocardial ischaemia-reperfusion injury (MI/RI) is unclear.

OBJECTIVE

This study evaluates the cardioprotective effect and molecular mechanism of XBW against MI/RI.

MATERIALS AND METHODS

A phytochemistry-based network pharmacology analysis was used to uncover the mechanism of XBW against MI/RI. Ultra performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry method was used to identify chemicals. MI/RI-related targets of XBW were predicted using TargetNet database, OMIC database, etc. Sprague-Dawley (SD) rats under anterior descending artery ligation model were divided into Sham, MI/RI and XBW (180 mg/kg, intragastric administration). After 30 min ischaemia and 24 h reperfusion, heart tissues were collected for measurement of myocardial infarct size. After oxygen glucose deprivation for 6 h, H9c2 cells were treated with XBW (60, 240 and 720 μg/mL) and diazoxide (100 μM) for 18 h of reperfusion.

RESULTS

Thirty-seven chemicals were identified in XBW; 50 MI/RI-related targets of XBW were predicted using indicated databases. XBW significantly reduced infarct size and creatine kinase MB (CK-MB) level after MI/RI; XBW protected H9c2 cells against OGD/R injury. Gene ontology (GO) and KEGG pathway enrichment analyses by String database showed that the cardioprotective effect of XBW was associated with autophagy and apoptosis signalling pathways. Experimental investigation also verified that XBW suppressed apoptosis, autophagy and endoplasmic reticulum (ER) stress.

CONCLUSIONS

XBW showed therapeutic effects against MI/RI mainly via attenuating apoptosis though suppressing excessive autophagy and ER stress.

Benzophenones alter autophagy and ER stress gene expression in pancreatic beta cells in vitro

Benzophenones (BPs) are endocrine disruptors frequently used in sunscreens and food packaging as UV blockers. Our goal was to assess the effect of benzophenone 2 (BP2) and 3 (BP3) on gene expression related to autophagy process and ER stress response in pancreatic beta cells. To that end, the mouse pancreatic beta cell line MIN6B1 was treated with 10 µM BP2 or BP3 in the presence or absence of the autophagy-inhibitor chloroquine (CQ, 10 µM) or the autophagy-inducer rapamycin (RAPA, 50 nM) during 24 h. BP3 inhibited the expression of the autophagic gene Ulk1, and additional effects were uncovered when autophagy was modified by CQ and RAPA. BP3 counteracted CQ-induced Lamp2 expression but did not compensate CQ-induced Sqstm1/p62 gene transcription, neither BP2. Nevertheless, the BPs did not alter the autophagic flux. In relation to ER stress, BP3 inhibited unspliced and spliced Xbp1 mRNA levels in the presence or absence of CQ, totally counteracted CQ-induced Chop gene expression, and partially reverted CQ-induced Grp78/Bip mRNA levels, while BP2 also partially inhibited Grp78/Bip mRNA induction by CQ. In conclusion, BPs, principally BP3, affect cellular adaptive responses related to autophagy, lysosomal biogenesis, and ER stress in pancreatic beta cells, indicating that BP exposure could lead to beta cell dysfunction.

Modulation of endoplasmic reticulum stress via sulforaphane-mediated AMPK upregulation against nonalcoholic fatty liver disease in rats

Nonalcoholic fatty liver disease (NAFLD) is a major health concern. Endoplasmic reticulum (ER) stress, inflammation, and metabolic dysfunctions may be targeted to prevent the progress of nonalcoholic fatty liver disease. Sulforaphane (SFN), a sulfur-containing compound that is abundant in broccoli florets, seeds, and sprouts, has been reported to have beneficial effects on attenuating metabolic diseases. In light of this, the present study was designed to elucidate the mechanisms by which SFN ameliorated ER stress, inflammation, lipid metabolism, and insulin resistance - induced by a high-fat diet and ionizing radiation (IR) in rats. In our study, the rats were randomly divided into five groups: control, HFD, HFD + SFN, HFD + IR, and HFD + IR + SFN groups. After the last administration of SFN, liver and blood samples were taken. As a result, the lipid profile, liver enzymes, glucose, insulin, IL-1β, adipokines (leptin and resistin), and PI3K/AKT protein levels, as well as the mRNA gene expression of ER stress markers (IRE-1, sXBP-1, PERK, ATF4, and CHOP), fatty acid synthase (FAS), peroxisome proliferator-activated receptor-α (PPAR-α). Interestingly, SFN treatment modulated the levels of proinflammatory cytokine including IL-1β, metabolic indices (lipid profile, glucose, insulin, and adipokines), and ER stress markers in HFD and HFD + IR groups. SFN also increases the expression of PPAR-α and AMPK genes in the livers of HFD and HFD + IR groups. Meanwhile, the gene expression of FAS and CHOP was significantly attenuated in the SFN-treated groups. Our results clearly show that SFN inhibits liver toxicity induced by HFD and IR by ameliorating the ER stress events in the liver tissue through the upregulation of AMPK and PPAR-α accompanied by downregulation of FAS and CHOP gene expression.

Chronic exposure to environmentally relevant levels of di(2-ethylhexyl) phthalate (DEHP) disrupts lipid metabolism associated with SBP-1/SREBP and ER stress in C. elegans

DEHP is commonly found in the environment, biota, food, and humans, raising significant health concerns. Whether developmental stage and exposure duration modify the obesogenic effects of DEHP is unclear, especially the underlying mechanisms by which chronic exposure to DEHP as well as its metabolites remain largely unknown. This study investigated the obesogenic effects of chronic DEHP exposure, with levels below environmentally-relevant amounts and provide the mechanism in Caenorhabditis elegans. We show that early-life DEHP exposure resulted in an increased lipid and triglyceride (TG) accumulation mainly attributed to DEHP itself, not its metabolite mono-2-ethylhexyl phthalate (MEHP). In addition, developmental stage and exposure timing influence DEHP-induced TG accumulation and chronic DEHP exposure resulted in the most significant effect. Analysis of fatty acid composition shows that chronic DEHP exposure altered fatty acid composition and TG, resulting in an increased ω-6/ω-3 ratio. The increased TG content by chronic DEHP exposure required lipogenic genes fat-6, fat-7, pod-2, fasn-1, and sbp-1. Moreover, chronic DEHP exposure induced XBP-1-mediated endoplasmic reticulum (ER) stress which might lead to up-regulation of sbp-1. This study suggests the possible involvement of ER stress and SBP-1/SREBP-mediated lipogenesis in chronic DEHP-induced obesogenic effects. Results from this study implies that chronic exposure to DEHP disrupts lipid metabolism, which is likely conserved across species due to evolutionary conservation of molecular mechanisms, raising concerns in ecological and human health.

Fic-mediated AMPylation tempers the unfolded protein response during physiological stress

The proper balance of synthesis, folding, modification, and degradation of proteins, also known as protein homeostasis, is vital to cellular health and function. The unfolded protein response (UPR) is activated when the mechanisms maintaining protein homeostasis in the endoplasmic reticulum become overwhelmed. However, prolonged or strong UPR responses can result in elevated inflammation and cellular damage. Previously, we discovered that the enzyme filamentation induced by cyclic-AMP (Fic) can modulate the UPR response via posttranslational modification of binding immunoglobulin protein (BiP) by AMPylation during homeostasis and deAMPylation during stress. Loss of fic in Drosophila leads to vision defects and altered UPR activation in the fly eye. To investigate the importance of Fic-mediated AMPylation in a mammalian system, we generated a conditional null allele of Fic in mice and characterized the effect of Fic loss on the exocrine pancreas. Compared to controls, Fic-/- mice exhibit elevated serum markers for pancreatic dysfunction and display enhanced UPR signaling in the exocrine pancreas in response to physiological and pharmacological stress. In addition, both fic-/- flies and Fic-/- mice show reduced capacity to recover from damage by stress that triggers the UPR. These findings show that Fic-mediated AMPylation acts as a molecular rheostat that is required to temper the UPR response in the mammalian pancreas during physiological stress. Based on these findings, we propose that repeated physiological stress in differentiated tissues requires this rheostat for tissue resilience and continued function over the lifetime of an animal.

Dendrobine inhibits dopaminergic neuron apoptosis via MANF-mediated ER stress suppression in MPTP/MPP+-induced Parkinson's disease models

BACKGROUND

Parkinson's disease (PD) is an age-related neurodegenerative disorder without effective treatments. Mesencephalic astrocyte-derived neurotrophic factor (MANF) has been suggested to be capable of protecting against PD by inhibiting endoplasmic reticulum (ER) stress-mediated neuronal apoptosis.

PURPOSE

This study was aimed to evaluate the antiparkinsonian effect of dendrobine and reveal its underlying mechanisms from the perspective of MANF-mediated ER stress suppression.

METHODS

Behavioral assessments of PD mice as well as LDH/CCK-8 assay in SH-SY5Y cells and primary midbrain neurons were carried out to detect the antiparkinsonian effect of dendrobine. Immunofluorescence, western blot, flow cytometry and shRNA-mediated MANF knockdown were used to determine the apoptosis of dopaminergic neurons and the expressions of ER stress-related proteins for investigating the underlying mechanism of dendrobine.

RESULTS

Dendrobine significantly ameliorated the motor performance of PD mice and attenuated the injuries of dopaminergic neurons. Dendrobine could also relieve neuronal apoptosis, up-regulate MANF expression and inhibit ER stress, which were largely abolished by shRNA-mediated MANF knockdown in PD model.

CONCLUSION

Dendrobine might protect against PD by inhibiting dopaminergic neuron apoptosis, which was achieved by facilitating MANF-mediated ER stress suppression. Our study suggested that dendrobine could act as a MANF up-regulator to protect against PD, and provided a potential candidate for exploring etiological agents of PD.

Ubiquitin-like modifier 1 ligating enzyme 1 relieves cisplatin-induced premature ovarian failure by reducing endoplasmic reticulum stress in granulosa cells

BACKGROUND

Ubiquitin-like modifier 1 ligating enzyme 1 (UFL1), the ligase of the UFMylation system, has recently been reported to be involved in apoptosis and endoplasmic reticulum stress (ER stress) in a variety of diseases. Premature ovarian failure (POF) is a gynecological disease that severely reduces the fertility of women, especially in female cancer patients receiving chemotherapy drugs. Whether UFL1 is involved in protection against chemotherapy-induced POF and its mechanism remain unclear.

METHODS

In this study, we examined the function of UFL1 in ovarian dysfunction and granulosa cell (GC) apoptosis induced by cisplatin through histological examination and cell viability analysis. We used western blotting, quantitative real-time PCR (qPCR) and immunofluorescence (IF) to detect the expression of UFL1 and the levels of ER stress specific markers. Enzyme linked immunosorbent assays were used to detect the levels of follicle-stimulating hormone (FSH) and estrogen (E₂) in ovaries and GCs. In addition, we used infection with lentiviral particle suspensions to knock down and overexpress UFL1 in ovaries and GCs, respectively.

RESULTS

Our data showed that the expression of UFL1 was reduced in POF model ovaries, accompanied by ER stress. In vitro, cisplatin induced a stress-related increase in UFL1 expression in GCs and enhanced ER stress, which was aggravated by UFL1 knockdown and alleviated by UFL1 overexpression. Furthermore, UFL1 knockdown resulted in a decrease in ovarian follicle number, an increase in atretic follicles, and decreased expression of AMH and FSHR. Conversely, the overexpression of UFL1 reduced cisplatin-induced damage to the ovary in vitro.

CONCLUSIONS

Our research indicated that UFL1 regulates cisplatin-induced ER stress and apoptosis in GCs, and participates in protection against cisplatin-induced POF, providing a potential therapeutic target for the clinical prevention of chemotherapeutic drug-induced POF.

Glaucocalyxin A impairs tumor growth via amplification of the ATF4/CHOP/CHAC1 cascade in human oral squamous cell carcinoma

ETHNOPHARMACOLOGICAL RELEVANCE

The natural extract glaucocalyxin A (GLA), purified from the aboveground sections of the Chinese traditional medicinal herb Rabdosia japonica (Burm. f.) Hara var. glaucocalyx (Maxim.) Hara, has various pharmacological benefits, such as anti-bacterial, anti-coagulative, anti-neoplastic, and anti-inflammatory activities. Although GLA has shown anti-tumor activity against various cancers, the therapeutic potential and biological mechanisms of GLA remain to be further explored in oral squamous cell carcinoma (OSCC).

AIM OF THE STUDY

This study aimed to elucidate the therapeutic potential and regulatory mechanisms of GLA in OSCC.

MATERIALS AND METHODS

The cell proliferation and apoptosis effects of GLA were analyzed by CCK-8, clone formation, Annexin V/PI staining, and apoptotic protein expression in vitro. An OSCC xenograft model was applied to confirm the anti-neoplastic effect in vivo. Furthermore, the changes of reactive oxygen species (ROS) were determined by DCFH-DA probe and GSH/GSSG assay, and inhibited by the pan-caspase inhibitor Z-VAD(OMe)-FMK and the ROS scavenger N-acetylcysteine (NAC). The modulation of GLA on mitochondria and ER-dependent apoptosis pathways was analyzed by JC-1 probe, quantitative real-time PCR, and Western blot. Finally, public databases, clinical samples, and transfection cells were analyzed to explore the importance of GLA's indirect targeting molecule CHAC1 in OSCC.

RESULTS

GLA significantly inhibited cell proliferation and induced apoptosis in vitro and in vivo. GLA perturbed the redox homeostasis, and cell apoptosis was totally rescued by Z-VAD(OMe)-FMK and NAC. Furthermore, GLA activated the mitochondrial apoptosis pathway. Simultaneously, the overexpression and knockdown of CHAC1 dramatically affected GLA-mediated apoptosis. The endoplasmic reticulum stress-associated ATF4/CHOP signal was identified to participate in GLA-upregulated CHAC1 expression. Finally, we found that CHAC1 expression was lower in OSCC compared with normal tissues and positively correlated with 4-Hydroxynonenal (4-HNE) level. High CHAC1 expression also indicated better overall survival. Moreover, CHAC1 selectively regulated the viability of oral cancer cells.

CONCLUSION

GLA is a promising therapeutic agent that activates the ROS-mediated ATF4/CHOP/CHAC1 axis in OSCC patients.

Resveratrol and regular exercise may attenuate hypertension-induced cardiac dysfunction through modulation of cellular stress responses

AIMS

Hypertension is one of the major causes of cardiac damage. In this study, the effects of resveratrol supplementation and regular exercise on hypertension-induced cellular stress responses of myocardium were compared.

MAIN METHODS

Hypertension was induced in male Wistar rats by deoxycorticosterone-acetate + salt administration for 12 weeks. Resveratrol and regular exercise were applied for the last six weeks. In addition to biochemical and molecular examinations, isoprenaline, phenylephrine and, acetylcholine-mediated contractions and sinus rate were recorded in the isolated cardiac tissues.

KEY FINDINGS

Resveratrol and regular exercise reduced systolic blood pressure in hypertensive rats. The altered adrenergic and cholinergic responses of the right atrium and left papillary muscles in hypertension were separately improved by resveratrol and regular exercise. Resveratrol and regular exercise decreased plasma and cardiac total antioxidant capacity and, augmented the expression of antioxidant genes in hypertensive rats. While regular exercise restored the increase in p-PERK expression associated with endoplasmic reticulum stress and decrease in mitophagic marker PINK1 expression, resveratrol only ameliorated PINK1 expression in hypertensive rats. Resveratrol and exercise training suppressed hypertension-induced NLRP3 inflammasome activation by reversing the increase in NLRP3, p-NF-κB expression and the mature-IL-1β/pro-IL-1β and cleaved-caspase-1/pro-caspase-1 ratio. Resveratrol and exercise enhanced mRNA expression of caspase-3, bax, and bcl-2 involved in the apoptotic pathway, but attenuated phosphorylation of stress-related mitogenic proteins p38 and JNK induced by hypertension.

SIGNIFICANCE

Our study demonstrated the protective effect of resveratrol and exercise on hypertension-induced cardiac dysfunction by modulating cellular stress responses including oxidative stress, ER stress, mitophagy, NLRP3 inflammasome-mediated inflammation, and mitogenic activation.

Qingluotongbi formula regulates the LXRα-ERS-SREBP-1c pathway in hepatocytes to alleviate the liver injury caused by Tripterygium wilfordii Hook. f

ETHNOPHARMACOLOGICAL RELEVANCE

Tripterygium wilfordii Hook. f. (TW) is widely used to treat autoimmune and inflammatory diseases; however, its development and application is limited by its significant association with liver injury. The compound formula Qingluotongbi (QLT) employs TW as its main component and is used to treat rheumatoid arthritis with no adverse reactions, suggesting that QLT may reduce the liver toxicity of TW.

AIM OF THE STUDY

We examined whether TW interferes with lipid metabolism to induce liver injury, and evaluated the protective effect of QLT in in vivo and in vitro experiments.

MATERIALS AND METHODS

After administration of QLT and its ingredients, HepaRG cells and SD rats were tested for biochemical indicators, hepatocytes lipid changes, and rat liver pathological changes, and then we analyzed for the gene expression of liver X receptor α (LXRα), endoplasmic reticulum stress (ERS) key proteins, sterol regulatory element binding protein-1c (SREBP-1c), and lipid-synthesizing enzymes. In HepaRG cells, the protein expression of glucose-regulated protein 78 kDa (GRP78) and LXRα was detected after addition of an LXRα inhibitor, LXRα agonist, and ERS inhibitor.

RESULTS

TW caused significant elevation of biochemical indicators and lipid droplet deposition in hepatocytes, as well as upregulated the gene expression of LXRα, ERS key proteins, SREBP-1c, and lipid-synthesizing enzymes in both in vitro and in vivo settings, and caused liver injury in rats. QLT can alleviate the lipotoxic liver injury caused by TW. LXRα agonist further activated ERS induced by TW, whereas LXRα inhibitor significantly reduced ERS and lipotoxic injury induced by TW in HepaRG cells.

CONCLUSIONS

TW upregulated LXRα to activate ERS and increased the gene expression of SREBP-1c and lipid-synthesizing enzymes, leading to increased lipid synthesis in hepatocytes to result in liver injury. QLT inhibited the LXRα-ERS-SREBP-1c pathway and reduced abnormal lipid synthesis in hepatocytes and the hepatotoxicity of TW.

Anticancer effects of Pimaric acid is mediated via endoplasmic reticulum stress, caspase-dependent apoptosis, cell cycle arrest, and inhibition of cell migration in human ovarian cancer cells

Pimaric acid is a naturally occurring resin and has been found to perform many pharmacological activities including, anticancer activity. However, the role of Pimaric acid in ovarian cancer is still not known. This investigation aimed to evaluate the anticancer effects of Pimaric acid and its molecular mechanism in human ovarian cancer cells. MTT assay was used to examine cell viability. Cell morphology was determined through phase contrast microscopy. DAPI staining and TUNEL assay were performed for apoptotic study. Examination of cell cycle phase distribution was carried out through flow cytometry. In vitro wound healing assay was used for cell migration determination. Pimaric acid induced cytotoxicity in human ovarian cancer cells (PA-1) in a dose-dependent manner without causing too much cytotoxicity in human ovarian epithelial cells (T1074). Cell morphology in treated cancer cells showed significant changes compared to untreated controls. Furthermore, it was observed that the cytotoxic effects of Pimaric acid were apoptosis-mediated and caspase-dependent cascade. Western blotting analysis showed that the expression of apoptosis-associated proteins like BAX, p-53 and caspase-3 was enhanced and BCL-2 expression was diminished. The induction of cytotoxicity was mediated via endoplasmic reticulum stress through expressions of related proteins which showed a tremendous increase in p-PERK, PERK, AT-4, CHOP and IRE-1 levels after treatment. Cell cycle analysis through cytometry showed significant results as it revealed G2/M phase cell cycle arrest. Furthermore, the in vitro wound healing assay showed specific anti-migratory effects of Pimaric acid on PA-1 cells. In conclusion it can be assumed that Pimaric acid may act as a potential anticancer agent against ovarian carcinoma, however further investigations are required to validate this initial claim.

The role of GRP78 in oxidative stress induced by tunicamycin in trabecular meshwork cells

OBJECTIVE

To clarify the regulatory effect of GRP-78 induced by tunicamycin on endoplasmic reticulum (ER) stress.

METHODS

Tunicamycin was used to induce ER stress in trabecular meshwork cells (HTMC and GTM3). Cell apoptosis and ROS content were detected by flow cytometry to reveal the effect of tunicamycin on trabecular meshwork cells.

RESULTS

Tunicamycin could significantly increase the ROS content and the apoptosis rate in HTMC and GTM3 (p<0.01). The results showed that tunicamycin could increase the Ca2+ flow in cells. Tunicamycin can also increase expression levels of GRP78,VDAC1, ATF4, PERK, eIF2a, and CHOP (p<0.01). Overexpression of GRP78 protected cells from ER stress. Co-IP test showed that GRP78 directly bound to eIF2. These results suggest that GRP78 may play a regulatory role by regulating eIF2.

CONCLUSION

Tunicamycin induces oxidative stress in trabecular meshwork cells, and the increase in GRP78 expression can protect the cells during ER stress by regulating eIF2.

Indigofera linifolia ameliorated CCl4 induced endoplasmic reticulum stress in liver of rat

ETHNOPHARMACOLOGICAL RELEVANCE

Indigofera linifolia (L.f.) Retz. is used in subcontinent for liver disorders, in wounds, febrile eruption and as diuretic.

AIM OF STUDY

The current study evaluates the protective effects of the methanol extract of Indigofera linifolia (ILM) on CCl₄-induced endoplasmic reticulum (ER) stress in liver of rat.

METHODS

ILM was analyzed for phytochemical classes, total phenolic (TPC) and flavonoid content (TFC) as well as multidimensional in vitro antioxidant assays. Male (Sprague Dawley) rats were dispersed into seven groups (6 rats/group) receiving 0.9% saline (1 ml/kg bw), CCl₄ (1 ml/kg bw) diluted in olive oil (3:7 v/v), silymarin (200 mg/kg bw) + CCl₄ (30% v/v), ILM (150 mg/kg bw) + CCl₄ (30% v/v), ILM (300 mg/kg bw) + CCl₄ and ILM alone (either 150 mg/kg bw or 300 mg/kg bw).

RESULTS

ILM extract was constituted of different phytochemical classes. Co-administration of ILM along with CCl₄ to rat revert the level of alanine transaminase (ALT), aspartate transaminase (AST), alkaline phosphatase (ALP) and total bilirubin in blood serum and antioxidant parameters in liver. Further, CCl₄ increased the level of ER stress markers and inflammatory mediators while decreased level of GCLC and Nrf-2 in liver tissues of rat. CCl₄-induced histopathological variations were reduced with ILM co-administration in liver tissues.

CONCLUSION

The results suggest that active phyto-constituents of I. linifolia might be responsible for its antioxidant, anti-inflammatory and gene-regulating activities.

Inhibition of endoplasmic reticulum stress combined with activation of angiotensin-converting enzyme 2: novel approach for the prevention of endothelial dysfunction in type 1 diabetic rats

Persistent hyperglycemia in type 1 diabetes triggers numerous signaling pathways, which may prove deleterious to the endothelium. As hyperglycemia damages the endothelial layer via multiple signaling pathways, including enhanced oxidative stress, downregulation of angiotensin-converting enzyme 2 signaling, and exacerbation of endoplasmic reticulum (ER) stress, it becomes difficult to prevent injury using monotherapy. Thus, the present study was conceived to evaluate the combined effect of ER stress inhibition along with angiotensin-converting enzyme 2 activation, two major contributors to hyperglycemia-induced endothelial dysfunction, in preventing endothelial dysfunction associated with type 1 diabetes. Streptozotocin-induced diabetic animals were treated with either diminazene aceturate (5 mg·kg-1 per day, p.o.) or tauroursodeoxycholic acid, sodium salt (200 mg·kg-1 per day i.p.), or both for 4 weeks. Endothelial dysfunction was evaluated using vasoreactivity assay, where acetylcholine-induced relaxation was assessed in phenylephrine pre-contracted rings. Combination therapy significantly improved vascular relaxation when compared with diabetic control as well as monotherapy. Restoration of nitrite levels along with prevention of collagen led to improved vasodilatation. Moreover, there was an overall reduction in aortic oxidative stress. We conclude that by simultaneously inhibiting ER stress and activating angiotensin-converting enzyme 2 deleterious effects of hyperglycemia on endothelium were significantly alleviated. This could serve as a novel strategy for the prevention of endothelial dysfunction.

Imeglimin Ameliorates β-Cell Apoptosis by Modulating the Endoplasmic Reticulum Homeostasis Pathway

The effects of imeglimin, a novel antidiabetes agent, on β-cell function remain unclear. Here, we unveiled the impact of imeglimin on β-cell survival. Treatment with imeglimin augmented mitochondrial function, enhanced insulin secretion, promoted β-cell proliferation, and improved β-cell survival in mouse islets. Imeglimin upregulated the expression of endoplasmic reticulum (ER)-related molecules, including Chop (Ddit3), Gadd34 (Ppp1r15a), Atf3, and Sdf2l1, and decreased eIF2α phosphorylation after treatment with thapsigargin and restored global protein synthesis in β-cells under ER stress. Imeglimin failed to protect against ER stress-induced β-cell apoptosis in CHOP-deficient islets or in the presence of GADD34 inhibitor. Treatment with imeglimin showed a significant decrease in the number of apoptotic β-cells and increased β-cell mass in Akita mice. Imeglimin also protected against β-cell apoptosis in both human islets and human pluripotent stem cell-derived β-like cells. Taken together, imeglimin modulates the ER homeostasis pathway, which results in the prevention of β-cell apoptosis both in vitro and in vivo.

Cannabidiol inhibits SARS-CoV-2 replication through induction of the host ER stress and innate immune responses

The spread of SARS-CoV-2 and ongoing COVID-19 pandemic underscores the need for new treatments. Here we report that cannabidiol (CBD) inhibits infection of SARS-CoV-2 in cells and mice. CBD and its metabolite 7-OH-CBD, but not THC or other congeneric cannabinoids tested, potently block SARS-CoV-2 replication in lung epithelial cells. CBD acts after viral entry, inhibiting viral gene expression and reversing many effects of SARS-CoV-2 on host gene transcription. CBD inhibits SARS-CoV-2 replication in part by up-regulating the host IRE1α RNase endoplasmic reticulum (ER) stress response and interferon signaling pathways. In matched groups of human patients from the National COVID Cohort Collaborative, CBD (100 mg/ml oral solution per medical records) had a significant negative association with positive SARS-CoV-2 tests. This study highlights CBD as a potential preventative agent for early-stage SARS-CoV-2 infection and merits future clinical trials. We caution against use of non-medical formulations including edibles, inhalants or topicals as a preventative or treatment therapy at the present time.

SGLT2 inhibitors therapy protects glucotoxicity-induced β-cell failure in a mouse model of human KATP-induced diabetes through mitigation of oxidative and ER stress

Progressive loss of pancreatic β-cell functional mass and anti-diabetic drug responsivity are classic findings in diabetes, frequently attributed to compensatory insulin hypersecretion and β-cell exhaustion. However, loss of β-cell mass and identity still occurs in mouse models of human KATP-gain-of-function induced Neonatal Diabetes Mellitus (NDM), in the absence of insulin secretion. Here we studied the temporal progression and mechanisms underlying glucotoxicity-induced loss of functional β-cell mass in NDM mice, and the effects of sodium-glucose transporter 2 inhibitors (SGLT2i) therapy. Upon tamoxifen induction of transgene expression, NDM mice rapidly developed severe diabetes followed by an unexpected loss of insulin content, decreased proinsulin processing and increased proinsulin at 2-weeks of diabetes. These early events were accompanied by a marked increase in β-cell oxidative and ER stress, without changes in islet cell identity. Strikingly, treatment with the SGLT2 inhibitor dapagliflozin restored insulin content, decreased proinsulin:insulin ratio and reduced oxidative and ER stress. However, despite reduction of blood glucose, dapagliflozin therapy was ineffective in restoring β-cell function in NDM mice when it was initiated at >40 days of diabetes, when loss of β-cell mass and identity had already occurred. Our data from mouse models demonstrate that: i) hyperglycemia per se, and not insulin hypersecretion, drives β-cell failure in diabetes, ii) recovery of β-cell function by SGLT2 inhibitors is potentially through reduction of oxidative and ER stress, iii) SGLT2 inhibitors revert/prevent β-cell failure when used in early stages of diabetes, but not when loss of β-cell mass/identity already occurred, iv) common execution pathways may underlie loss and recovery of β-cell function in different forms of diabetes. These results may have important clinical implications for optimal therapeutic interventions in individuals with diabetes, particularly for those with long-standing diabetes.

Pt(II)-NHC Complex Induces ROS-ERS-Related DAMP Balance to Harness Immunogenic Cell Death in Hepatocellular Carcinoma

Immunogenic cell death (ICD) can engage a specific immune response and establish a long-term immunity in hepatocellular carcinoma (HCC). Herein, we design and synthesize a series of Pt(II)-N-heterocyclic carbene (Pt(II)-NHC) complexes derived from 4,5-diarylimidazole, which show strong anticancer activities in vitro. Among them, 2c displays much higher anticancer activities than cisplatin and other Pt(II)-NHC complexes, especially in HCC cancer cells. In addition, we find that 2c is a type II ICD inducer, which can successfully induce endoplasmic reticulum stress (ERS) accompanied by reactive oxygen species (ROS) generation and finally lead to the release of damage-associated molecular patterns (DAMPs) in HCC cells. Importantly, 2c shows a great anti-HCC potential in a vaccination mouse model and leads to the in vivo immune cell activation in the CCl4-induced liver injury model.

Allicin Improves Intestinal Epithelial Barrier Function and Prevents LPS-Induced Barrier Damages of Intestinal Epithelial Cell Monolayers

Gut barrier disruption is the initial pathogenesis of various diseases. We previously reported that dietary allicin improves tight junction proteins in the endoplasmic reticulum stressed jejunum. However, whether the allicin benefits the gut barrier within mycotoxin or endotoxin exposure is unknown. In the present study, IPEC-J2 cell monolayers within or without deoxynivalenol (DON) or lipopolysaccharide (LPS) challenges were employed to investigate the effects of allicin on intestinal barrier function and explore the potential mechanisms. Results clarified that allicin at 2 μg/mL increased the viability, whereas the allicin higher than 10 μg/mL lowered the viability of IPEC-J2 cells via inhibiting cell proliferation. Besides, allicin increased trans-epithelial electric resistance (TEER), decreased paracellular permeability, and enhanced ZO-1 integrity of the IPEC-J2 cell monolayers. Finally, allicin supplementation prevented the LPS-induced barrier damages via activating Nrf2/HO-1 pathway-dependent antioxidant system. In conclusion, the present study strongly confirmed allicin as an effective nutrient to improve intestinal barrier function and prevent bacterial endotoxin-induced barrier damages.

Reversing mitochondrial defects in aged hearts: role of mitochondrial calpain activation

Aging chronically increases endoplasmic reticulum (ER) stress that contributes to mitochondrial dysfunction. Activation of calpain 1 (CPN1) impairs mitochondrial function during acute ER stress. We proposed that aging-induced ER stress led to mitochondrial dysfunction by activating CPN1. We posit that attenuation of the ER stress or direct inhibition of CPN1 in aged hearts can decrease cardiac injury during ischemia-reperfusion by improving mitochondrial function. Male young (3 mo) and aged mice (24 mo) were used in the present study, and 4-phenylbutyrate (4-PBA) was used to decrease the ER stress in aged mice. Subsarcolemmal (SSM) and interfibrillar mitochondria (IFM) were isolated. Chronic 4-PBA treatment for 2 wk decreased CPN1 activation as shown by the decreased cleavage of spectrin in cytosol and apoptosis inducing factor (AIF) and the α1 subunit of pyruvate dehydrogenase (PDH) in mitochondria. Treatment improved oxidative phosphorylation in 24-mo-old SSM and IFM at baseline compared with vehicle. When 4-PBA-treated 24-mo-old hearts were subjected to ischemia-reperfusion, infarct size was decreased. These results support that attenuation of the ER stress decreased cardiac injury in aged hearts by improving mitochondrial function before ischemia. To challenge the role of CPN1 as an effector of the ER stress, aged mice were treated with MDL-28170 (MDL, an inhibitor of calpain 1). MDL treatment improved mitochondrial function in aged SSM and IFM. MDL-treated 24-mo-old hearts sustained less cardiac injury following ischemia-reperfusion. These results support that age-induced ER stress augments cardiac injury during ischemia-reperfusion by impairing mitochondrial function through activation of CPN1.

Compound Tongluo Decoction inhibits endoplasmic reticulum stress-induced ferroptosis and promoted angiogenesis by activating the Sonic Hedgehog pathway in cerebral infarction

ETHNOPHARMACOLOGICAL RELEVANCE

Cerebral infarction is one of the most common types of cerebrovascular diseases that threaten people's health. Compound Tongluo Decoction (CTLD), a traditional Chinese medicine formula, has various pharmacological activities, including the alleviation of cerebral infarction symptoms.

AIM OF THE STUDY

This study aims to explore the potential mechanism by which CTLD alleviates cerebral infarction.

MATERIAL AND METHODS

Middle cerebral artery occlusion (MCAO) rat model and oxygen-glucose deprivation and reperfusion (OGD/R) cell model were established for research. The expression of proteins related to endoplasmic reticulum (ER) stress, ferroptosis, Sonic Hedgehog (SHH) pathway and angiogenesis was analyzed by Western blot analysis. The expression of CD31 was detected by immunofluorescence to investigate angiogenesis. In addition, the expression of GRP78 and XBP-1 in brain tissues was investigated by immunohistochemistry. With the application of Prussian blue staining, iron deposition in brain tissue was detected. The levels of reactive oxygen species (ROS), malondialdehyde (MDA), superoxide dismutase (SOD) were detected using ELISA kits. The angiogenesis was analyzed by tube formation assay.

RESULTS

The results presented in this research showed that CTLD and 4-phenyl butyric acid (4-PBA; the inhibitor of ER stress) could alleviate cerebral infarction. Mechanistically, CTLD and 4-PBA rescued ER stress and ferroptosis, but promoted SHH signaling in rats with cerebral infarction. In addition, cerebral infarction exhibited a high level of angiogenesis, which was aggravated by CTLD but suppressed by 4-PBA. Furthermore, CTLD inhibited ER stress and ferroptosis, but promoted SHH signaling and angiogenesis in OGD/R-induced PC12 cells, which was partly abolished by SANT-1, an antagonist of SHH signaling.

CONCLUSION

In conclusion, this study revealed that CTLD might inhibit ferroptosis induced by endoplasmic reticulum stress and promote angiogenesis by activating the Sonic Hedgehog pathway in rats with cerebral infarction.

ISRIB plus bortezomib triggers paraptosis in breast cancer cells via enhanced translation and subsequent proteotoxic stress

Despite the success of proteasome inhibitors (PIs) in treating hematopoietic malignancies, including multiple myeloma (MM), their clinical efficacy is limited in solid tumors. In this study, we investigated the involvement of the integrated stress response (ISR), a central cellular adaptive program that responds to proteostatic defects by tuning protein synthesis rates, in determining the fates of cells treated with PI, bortezomib (Bz). We found that Bz induces ISR, and this can be reversed by ISRIB, a small molecule that restores eIF2B-mediated translation during ISR, in both Bz-sensitive MM cells and Bz-insensitive breast cancer cells. Interestingly, while ISRIB protected MM cells from Bz-induced apoptosis, it enhanced Bz sensitivity in breast cancer cells by inducing paraptosis, the cell death mode that is accompanied by dilation of the endoplasmic reticulum (ER) and mitochondria. Combined treatment with ISRIB and Bz may shift the fate of Bz-insensitive cancer cells toward paraptosis by inducing translational rescue, leading to irresolvable proteotoxic stress.

Luteolin ameliorates depression-like behaviors by suppressing ER stress in a mouse model of Alzheimer's disease

Alzheimer's disease (AD) is the most common cause of dementia in the elderly population. Inflammation plays an important role in AD, as microglia respond to several pathological insults, such as Aβ, and exert protective homeostatic functions (anti-inflammatory) and detrimental inflammatory functions (proinflammatory). During the development of AD, chronic inflammation that accompanies aging causes microglial priming, a state of hyperactivation in response to stimulation, indicating that suppressing microglial priming may be a therapeutic intervention for AD. Endoplasmic reticulum (ER) stress is crucial for inflammation through NF-kB and inflammasome activation. To identify natural flavonoids that regulate ER stress, a DNA microarray was performed using the brains of AD model mice after long-term intake of quercetin, after which the connectivity map (CMap) assay was carried out. We found that luteolin suppresses lipopolysaccharide (LPS)-induced interleukin 1β (IL1β) expression by inhibiting ER stress. Immunohistochemical analyses showed that CD68 levels were reduced in the brain after intraperitoneal injection of luteolin in a mouse model of AD, suppressing IL1β production. As shown by behavioral analyses using the tail suspension test (TST) and forced swimming test (FST), depression-like behaviors were ameliorated in luteolin-treated AD model mice. These findings indicate that luteolin prevents ER stress to suppress microglial activation in the brain, improving individual activity.

Tanshinone IIA alleviates NLRP3 inflammasome-mediated pyroptosis in Mycobacterium tuberculosis-(H37Ra-) infected macrophages by inhibiting endoplasmic reticulum stress

ETHNOPHARMACOLOGICAL RELEVANCE

Tanshinone IIA (Tan), extracted from Salvia miltiorrhiza Bunge, is a perennial herbal plant widely used as a folk remedy in Asian countries. Several studies have proved that Tanshinone IIA possesses many biological activities, such as anti-inflammatory, free-radical scavenging abilities, antioxidant properties, liver protection, and anti-cancer properties.

AIM OF THE STUDY

The objective of the present study was to examine the anti-inflammatory effects of Tan.

MATERIALS AND METHODS

The in vitro infection model of Mycobacterium tuberculosis-infected macrophages with the H37Ra strain was established. Murine macrophage Raw 264.7 and human monocyte THP-1 were used for the experiments. Cell viability was determined by the MTT assay. Western blot and lactate dehydrogenase (LDH) activity assays were used to detect the effects of Tan on cell pyroptosis and the level of NLRP3 inflammasome activation. Western blot, Co-immunoprecipitation and Immunofluorescence assays were used to observe the effect of Tan on the expression level of TXNIP. Immunofluorescence assays were applied to explore the effect of Tan on mtROS. Western blot and agarose gel electrophoresis were adopted to observe the effect of Tan on endoplasmic reticulum stress. The siRNA technique was applied to knockdown the expression levels of PERK/peIF2α, IRE1α and ATF6, and Western blot assay was employed to explore the NLRP3 inflammasome activation and possible molecular regulation mechanism of Tan.

RESULTS

This study demonstrated that Tan decreased Mtb-induced cell pyroptosis by measuring GSDMD-N and LDH release provoked by NLRP3 inflammasome activation. Additionally, Tan inhibited endoplasmic reticulum stress (ERS), mitochondrial damage, and TXNIP protein expression, all of which acted as upstream signals of NLRP3 inflammasome activation in Mtb-infected macrophages. Significantly, NLRP3 inflammasome activation was suppressed by knocking down ERS pathway proteins, which further clarified that Tan partly targeted ERS to exert anti-inflammatory and immunoregulatory actions.

CONCLUSION

This research confirms Tan's anti-inflammatory and immunoregulatory mechanisms in Mtb-infected macrophages by downregulating NLRP3 inflammasome activation-mediated pyroptosis provoked by ERS. Tan may function as an adjuvant drug to treat TB by adjusting host immune responses.