Autophagy protects gastric mucosal epithelial cells from ethanol-induced oxidative damage via mTOR signaling pathway

Protective effect of dimethyl fumarate against ethanol-provoked gastric ulcers in rats via regulation of HMGB1/TLR4/NF-κB, and PPARγ/SIRT1/Nrf2 pathways: Involvement of miR-34a-5p

Aberration of the gastric mucosal barrier homeostasis circuit is one of the key features linked to the onset of gastric ulcers (GU). This work aimed to inspect the gastroprotective influence of dimethyl fumarate (DMF) on ethanol-induced GU in rats and to decipher the possible mechanisms entailed. Rats were pretreated with either DMF (80 mg/kg) or omeprazole (OMP) (20 mg/kg) by oral gavage for 2 weeks. After 24 h of starvation, ethanol (5 ml/kg, oral) was employed to trigger GU in rats, while carboxymethyl cellulose (CMC) was used as a control. Ethanol notably elevated both macroscopic and microscopic gastric damage. DMF and OMP exhibited similar effects on gastric ulcer healing. DMF intervention led to a substantial improvement in gastric insults. DMF significantly reduced ethanol-triggered gastric lesions, as manifested by decreased gastric secretion, acidity, ulcer surface area percent, reduced leukocyte incursion, and increased mucus percent. DMF upregulated miR-34a-5p expression concomitant with the suppression of high mobility group box1 (HMGB1) and inflammatory responses in gastric mucosal homogenate. DMF improved GU by restoring reduced antioxidant defense mechanisms through the coactivation of nuclear factor erythroid 2-related factor-2 (Nrf2), peroxisome proliferator-activated receptor gamma (PPARγ), and sirtuin1 (SIRT1), indicating the protective role of the PPARγ/SIRT1/Nrf2 pathway. Intriguingly, DMF mitigated apoptosis in ethanol-elicited GU. Taken together, this research implies the potential for the repurposing of DMF as an innovative gastroprotective medication to reestablish the balance of the gastric mucosal barrier via the attenuation of gastric inflammation, oxidative stress, and apoptosis.

Enhanced upregulation of SIRT1 via pioglitazone and ligustrazine confers protection against ethanol-induced gastric ulcer in rats

Gastric ulcer is a disturbing disease that impacts many people worldwide. Pioglitazone (Piog), a thiazolidinedione, and ligustrazine (Ligu), a natural component of Ligusticum chuanxiong possess gastroprotective properties. However, the underlying mechanism is not well elucidated. The present study aimed to investigate the gastroprotective effects of Piog (15 mg/kg, p.o.), Ligu (15 mg/kg, p.o.), and their combination against ethanol-induced gastric ulcer in rats. Omeprazole (10 mg/kg) was used as a standard. Pre-treatment for 7 days with Piog, Ligu, and (Piog+Ligu) effectively alleviated ethanol-predisposed oxidative stress and inflammation through restoring HO-1, GSH, and SOD tissue levels and decreasing elevated MDA, TNF-α, ICAM, I-NOS, and IL-1β contents. Moreover, Piog, Ligu, and (Piog+Ligu) markedly inhibited the ethanol-induced increase of gastric NF-KB and BAX. In contrast, this pre-treatment regimen significantly accelerated protein expression of SIRT1, Nrf2, and Bcl-2, along with autophagic proteins, ATG5 and Beclin. Interestingly, macroscopic, histopathological examination and mucin content were in harmony with previous results, where pre-treatment with Piog, Ligu, and (Piog+Ligu) showed a declined mucosal injury as evidenced by the remarkable decrease of the ulcer area percentage by 62.3%, 38.7%, and 91.2%, respectively, compared to the ethanol-ulcerated group. In conclusion, Piog and Ligu exhibited remarkable gastroprotective properties. Our study was the first to show that Piog, Ligu, and (Piog+Ligu) ameliorated oxidative stress, inflammation, and apoptosis and accelerated the autophagic process via the upregulation of the upstream SIRT1 protein. It is worth mentioning that future studies are needed to pave the way for the clinical use of Piog and Ligu as gastro-protective agents.

Brain-derived neurotrophic factor - a key player in the gastrointestinal system

Brain-derived neurotrophic factor (BDNF) is highly expressed throughout the gastrointestinal (GI) tract and plays a critical role in the regulation of intestinal motility, secretion, sensation, immunity, and mucosal integrity. Dysregulation of BDNF signalling has been implicated in the pathophysiology of various GI disorders including inflammatory bowel disease, irritable bowel syndrome, functional dyspepsia, and diabetic gastroenteropathy. This review provides a comprehensive overview of BDNF localization, synthesis, receptors, and signalling mechanisms in the gut. In addition, current evidence on the diverse physiologic and pathophysiologic roles of BDNF in the control of intestinal peristalsis, mucosal transport processes, visceral sensation, neuroimmune interactions, gastrointestinal mucosal healing, and enteric nervous system homeostasis are discussed. Finally, the therapeutic potential of targeting BDNF for the treatment of functional GI diseases is explored. Advancing knowledge of BDNF biology and mechanisms of action may lead to new therapies based on harnessing the gut trophic effects of this neurotrophin.

Acetyl-L-carnitine attenuates chronic ethanol-induced oxidative stress, ER stress and apoptosis in rat gastric tissue

Consuming alcohol affects almost all organs. Acetaldehyde, formed as the main product as a result of alcohol metabolism, causes the production of free superoxide radicals when oxidized, and accordingly oxidative and apoptotic processes are triggered. There are studies showing that carnitine has effects on oxidative and apoptotic processes that occur in various conditions. However, the mechanisms showing the effects of L-carnitine on these effects of alcohol have not been fully elucidated. In our study, the effects of acetyl-L-carnitine administration on the molecular mechanisms of oxidative stress, endoplasmic reticulum stress, and apoptotic parameters in gastric tissue of rats chronically exposed to alcohol were investigated. Hematoxylin-eosin staining was used for histopathological studies. Endoplasmic reticulum stress markers were detected with immunohistochemical staining and western blotting. Apoptotic index was evaluated by terminal deoxynucleotidyl transferase dUTP nick-end labeling (TUNEL) assay. Total oxidant and antioxidant status were examined by ELISA. Our results showed that chronic alcohol administration caused a significant increase in TOS levels, an indicator of oxidative stress, the levels of ER-stress-associated proteins XBP1, GRP78, and CHOP, and % apoptotic index values in rat gastric tissues. Additionally, it was determined that acetyl-L-carnitine administration caused an improvement in those values. Based on our data, we can conclude that acetyl-L-carnitine has a tissue protective effect by scavenging free oxygen radicals and reducing ER stress-related proteins XBP1, GRP78, and CHOP and apoptosis in chronic ethanol-administered rats, and that this natural antioxidant may be beneficial in the treatment of oxidative stress-induced diseases.

Isolation, Structural Characteristics Analysis of a Vigna unguiculata Polysaccharide VUP80-3 and Its Protective Effect on GES-1 Cells In Vitro

Cowpea (Vigna unguiculata) is one of the main edible legume vegetables in China, and it can improve spleen and stomach function. A polysaccharide component (VUP80-3) has been isolated from V. unguiculata in this study. The average molecular weight of VUP80-3 is 6.43 × 10⁴ Da, and the main monosaccharide group is glucose. The mass ratio of monosaccharide groups in the polysaccharide was glucose:galactose:arabinose:rhamnose:xylose:mannose:fucose = 152.36:24.50:16.53:8.13:1.26:0.97:0.82. NMR analysis showed that VUP80-3 has →4)-α-D-Galp (1→ and →4)-α-D-Glcp(1→ main chain and →3,4)-β-D-Glcp(1→, →4,6)-α-D-Glcp(1→ branch chains, and the terminal sugar is α-D-Glcp(1→. Biological activity test results showed that VUP80-3 at 1000 μg·mL^-1 significantly increased the activity of ethanol injured GES-1 cells (p < 0.01) and significantly reduced reactive oxygen species (ROS) in ethanol injured GES-1 cells and inflammatory factors (IL-8, IL-1β and TNF-α,) in GES-1 cells. This compound also reduced the apoptosis rate (p < 0.05), thereby significantly reducing the oxidative damage caused by ethanol in GES-1 cells. Therefore, VUP80-3 is a potential drug to protect the gastric mucosa from damage.

Changes in the salivary metabolome in patients with chronic erosive gastritis

INTRODUCTION

Chronic erosive gastritis (CEG) is closely related to gastric cancer, which requires early diagnosis and intervention. The invasiveness and discomfort of electronic gastroscope have limited its application in the large-scale screening of CEG. Therefore, a simple and noninvasive screening method is needed in the clinic.

OBJECTIVES

The aim of this study is to screen potential biomarkers that can identify diseases from the saliva samples of CEG patients using metabolomics.

METHODS

Saliva samples from 64 CEG patients and 30 healthy volunteers were collected, and metabolomic analysis was performed using UHPLC-Q-TOF/MS in the positive and negative ion modes. Statistical analysis was performed using both univariate (Student's t-test) and multivariate (orthogonal partial least squares discriminant analysis) tests. Receiver operating characteristic (ROC) analysis was conducted to determine significant predictors in the saliva of CEG patients.

RESULTS

By comparing the saliva samples from CEG patients and healthy volunteers, 45 differentially expressed metabolites were identified, of which 37 were up-regulated and 8 were down-regulated. These differential metabolites were related to amino acid, lipid, phenylalanine metabolism, protein digestion and absorption, and mTOR signaling pathway. In the ROC analysis, the AUC values of 7 metabolites were greater than 0.8, among which the AUC values of 1,2-dioleoyl-sn-glycoro-3-phosphodylcholine and 1-stearoyl-2-oleoyl-sn-glycoro-3-phospholine (SOPC) were greater than 0.9.

CONCLUSIONS

In summary, a total of 45 metabolites were identified in the saliva of CEG patients. Among them, 1,2-dioleoyl-sn-glycoro-3-phosphorylcholine and 1-stearoyl-2-oleoyl-sn-glycoro-3-phosphorine (SOPC) might have potential clinical application value.

Gastroprotective activity of (E)-ethyl-12-cyclohexyl-4,5-dihydroxydodec-2-enoate, a compound isolated from Heliotropium indicum: role of nitric oxide, prostaglandins, and sulfhydryls in its mechanism of action

CONTEXT

The gastroprotective effect of Heliotropium indicum L. (Boraginaceae), a plant traditionally used in Mexico to treat gastric ulcers, has been previously reported. However, no active compound was identified.

OBJECTIVE

The current contribution aimed to isolate, through a bioassay-guided study, at least one compound from H. indicum with considerable gastroprotective activity, examine its effect on ethanol-induced gastric lesions in mice, and explore possible mechanisms of action.

MATERIALS AND METHODS

Three extracts (hexane, dichloromethane, and methanol) were obtained from H. indicum leaves. Their 30 and 100 mg/kg doses were assessed on ethanol-induced gastric lesions in male CD1 mice. Since the dichloromethane extract was the most active, successive chromatographies were carried out leading to the identification of the most active compound. This compound (at 3-100 mg/kg) was compared to carbenoxolone (at 10-100 mg/kg) in biological evaluations in mice. Pre-treatments with indomethacin (10 mg/kg, s.c.), L-NAME (70 mg/kg, i.p.), and NEM (10 mg/kg, s.c.) were performed independently to determine the participation of prostaglandins, nitric oxide, and/or sulfhydryl groups, respectively, in the mechanism of action of the compound.

RESULTS

(E)-Ethyl-12-cyclohexyl-4,5-dihydroxydodec-2-enoate, a compound isolated from H. indicum, afforded dose-dependent gastroprotective activity. The maximum effect was observed at 100 mg/kg (90.13 ± 3.08%), with an ED₅₀ of 5.92 ± 2.48 mg/kg. Gastroprotection was not modified by pre-treatment with indomethacin, L-NAME, or NEM.

CONCLUSIONS

(E)-Ethyl-12-cyclohexyl-4,5-dihydroxydodec-2-enoate, isolated from H. indicum, was found to produce a substantial gastroprotective effect. Prostaglandins, nitric oxide, and non-protein sulfhydryl groups are not involved in its mechanism of action.

Irbesartan reprofiling for the amelioration of ethanol-induced gastric mucosal injury in rats: Role of inflammation, apoptosis, and autophagy

BACKGROUND

Pronounced anti-inflammatory and anti-apoptotic features have been characterized for the angiotensin receptor blocker irbesartan. Yet, its effect on ethanol-induced gastropathy has not been studied. The present work explored the potential modulation of inflammatory, apoptotic, and autophagic events by irbesartan for the attenuation of ethanol-evoked gastric mucosal injury.

METHODOLOGY

Wistar rats were divided into control, control + irbesartan, ethanol, ethanol + irbesartan, and ethanol + omeprazole groups. Macroscopic examination, histopathology, immunohistochemistry, and biochemical assays were applied to examine the gastric tissues.

KEY FINDINGS

Irbesartan administration (50 mg/kg; by gavage) in ethanol-evoked gastropathy improved the gastric pathological manifestations (area of gastric lesion and ulcer index scores), histopathological changes, and microscopic damage scores. These beneficial effects were interceded by suppression of the HMGB1-associated inflammatory events and the linked downregulation of the nuclear NF-κBp65 protein expression. In the meantime, curtailing of the NLRP3 inflammasome by irbesartan was observed with consequent decline of the pro-inflammatory cytokine IL-1β. In tandem, upregulation of the antioxidant Nrf2 and the cytoprotective PPAR-γ were seen. Together, suppression of the pro-inflammatory cues and pro-oxidant signals attenuated the pro-apoptotic events as evidenced by Bcl-2 upregulation, Bax downregulation, and caspase 3 dampened activity. Regarding gastric autophagy signals, irbesartan diminished SQSTM-1/p62 accumulation and upregulated Beclin 1. This was associated with gastric AMPK/mTOR pathway activation evidenced by increased AMPK (Ser487) phosphorylation and lowered mTOR (Ser2448) phosphorylation.

CONCLUSION

Suppression of the inflammatory and apoptotic signals and upregulation of the pro-autophagy events may advocate the promising gastroprotective actions of irbesartan against ethanol-induced gastric injury.

Mulberry Ethanol Extract and Rutin Protect Alcohol-Damaged GES-1 Cells by Inhibiting the MAPK Pathway

Mulberry extract has been proven to have the effect of resisting alcohol damage, but its mechanism is still unclear. In this study, the composition of mulberry ethanol extract (MBE) was identified by LC-MS/MS and the main components of MBE were ascertained by measuring. Gastric mucosal epithelial (GES-1) cells were used to elucidate the mechanism of MBE and rutin (the central part of MBE) helped protect against alcohol damage. The results revealed that phenolics accounted for the majority of MBE, accounting for 308.6 mg/g gallic acid equivalents and 108 substances were identified, including 37 flavonoids and 50 non-flavonoids. The treatment of 400 μg/mL MBE and 320 μM rutin reduced early cell apoptosis and the content of intracellular reactive oxygen species, malondialdehyde and increased glutathione. The qPCR results indicated that the MBE inhibits the expression of genes in the mitogen-activated protein kinase (MAPK) pathway, including p38, JNK, ERK and caspase-3; rutin inhibits the expression of p38 and caspase-3. Overall, MBE was able to reduce the oxidative stress of GES-1 cells and regulated apoptosis-related genes of the MAPK pathway. This study provides information for developing anti-ethanol injury drugs or functional foods.

AMPK/mTOR-driven autophagy & Nrf2/HO-1 cascade modulation by amentoflavone ameliorates indomethacin-induced gastric ulcer

Gastric ulcer (GU) is a worldwide gastrointestinal disorder associated with NSAID use. Recently, amentoflavone proved to be a potent autophagy modulator, antioxidant, anti-inflammatory, and anti-apoptotic agent. Eight-week-old male Wistar rats received amentoflavone orally for 14 days at 25, 50, or 100 mg/kg/day. On day 14 of treatment, GU was induced by a single oral instillation of 100 mg/kg indomethacin, one hour after the last treatment. Amentoflavone dose-dependently alleviated indomethacin-induced GU, as demonstrated by repression of gastric mucosa pathological manifestations (ulcer index, ulcer surface area, histopathological deviations, and score) and increased ulcer inhibition percentage. These protective effects were due to the enhancement of gastric mucosa autophagy, as demonstrated by increased levels of beclin-1, MAP1LC3B, and CTSD, and reduced expression of p62 (SQSTM1). In addition, amentoflavone modulated the AMPK/mTOR pathway by increasing p-AMPK and reducing mTORC1 levels. Moreover, it hindered the redox aberrations by reducing MDA level and enhancing SOD activity, GSH level, and Nrf2/HO-1 cascade. Furthermore, a decrease in caspase-3 levels, Bax/Bcl-2 ratio and an increase in Bcl-2 expression suggest inhibition of the apoptotic process. Additionally, amentoflavone suppressed gastric mucosal inflammation by decreasing IL-1β, TNF-α, IFN-γ levels, IL-4, IL-6 mRNA expressions and MPO activity, and increasing IL-10 mRNA expresion. Therefore, amentoflavone could consider a promising natural agent protecting against indomethacin-induced GU.

Prophylactic Effect of Lactobacillus fermentum TKSN02 on Gastric Injury Induced by Hydrochloric Acid/Ethanol in Mice Through Its Antioxidant Capacity

In this article, the preventive and protective effect of a new Lactobacillus fermentum, (Lactobacillus fermentum TKSN02: LF-N2), which was isolated and identified from Xinjiang naturally fermented yogurt, on hydrochloric acid (HCl)/ethanol induced gastric injury in mice was studied. A total of 40 mice were divided into the following five groups: normal, model, LF-N2, LB (Lactobacillus bulgaricus), and Ranitidine groups. Except for the normal and model groups, mice in the other groups were treated with LF-N2, LB (Lactobacillus bulgaricus), and Ranitidine separately, and the injury of the gastric tissue was observed by taking photos and pathological sections. The levels of oxidation indicators, gastrointestinal hormone and the inflammatory cytokines in serum and gastric tissue in each group were measured. Further more, the gene expression levels of oxidative stress and inflammation related genes in the colon tissue were determined by the Real-Time PCR method. Pathological observation confirmed that LF-N2 could inhibit the gastric injury caused by HCl/ethanol. Observation of the appearance of the gastric indicated that LF-N2 could effectively reduce the area of gastric injury. Biochemical results showed that the serum gastrin (GAS) and gastric motilin (MTL) levels in the LF-N2 group were significantly lower and the serum somatostatin (SS) level was higher than in the model group and there was no significant difference between all treatment groups. The activities of total superoxide dismutase (T-SOD) and glutathione (GSH) were increased while the malondialdehyde (MDA) content was decreased in LF-N2 treatment group mice, which suggested that LF-N2 has a good antioxidant effect. Further RT-PCR experiments also showed that LF-N2 could promote the related mRNA expression of antioxidant enzymes (Cu/Zn-SOD, Mn-SOD, and CAT) and anti-inflammatory cytokines (IL-4, and IL-10), while it inhibited the gene expression of pro-inflammatory cytokine (IL-6) and apoptosis factor (Caspase-3). As observed, LF-N2 exerted a good preventive effect on HCl/ethanol induced gastric injury in mice, and the effect was close to that of LB, which indicated that LF-N2 has potential use as a probiotic due to its gastric injury treatment effects.

SARS-CoV-2 spike promotes inflammation and apoptosis through autophagy by ROS-suppressed PI3K/AKT/mTOR signaling

Background

Severe acute respiratory syndrome coronavirus-2 (SARS-CoV-2) infection-induced inflammatory responses are largely responsible for the death of novel coronavirus disease 2019 (COVID-19) patients. However, the mechanism by which SARS-CoV-2 triggers inflammatory responses remains unclear. Here, we aimed to explore the regulatory role of SARS-CoV-2 spike protein in infected cells and attempted to elucidate the molecular mechanism of SARS-CoV-2-induced inflammation.

Methods

SARS-CoV-2 spike pseudovirions (SCV-2-S) were generated using the spike-expressing virus packaging system. Western blot, mCherry-GFP-LC3 labeling, immunofluorescence, and RNA-seq were performed to examine the regulatory mechanism of SCV-2-S in autophagic response. The effects of SCV-2-S on apoptosis were evaluated by terminal deoxynucleotidyl transferase dUTP nick end labeling (TUNEL), Western blot, and flow cytometry analysis. Enzyme-linked immunosorbent assay (ELISA) was carried out to examine the mechanism of SCV-2-S in inflammatory responses.

Results

Angiotensin-converting enzyme 2 (ACE2)-mediated SCV-2-S infection induced autophagy and apoptosis in human bronchial epithelial and microvascular endothelial cells. Mechanistically, SCV-2-S inhibited the PI3K/AKT/mTOR pathway by upregulating intracellular reactive oxygen species (ROS) levels, thus promoting the autophagic response. Ultimately, SCV-2-S-induced autophagy triggered inflammatory responses and apoptosis in infected cells. These findings not only improve our understanding of the mechanism underlying SARS-CoV-2 infection-induced pathogenic inflammation but also have important implications for developing anti-inflammatory therapies, such as ROS and autophagy inhibitors, for COVID-19 patients.

Autophagy-lysosome dysfunction is involved in gastric ischemia-reperfusion injury by promoting microglial activation in the paraventricular nucleus

The hypothalamic paraventricular nucleus (PVN) is a specific center in the brain that regulates gastric mucosal injury following gastric ischemia-reperfusion (GI-R) injury. This study aimed to investigate whether autophagy-lysosome dysfunction in the PVN tissues of GI-R rats is involved in the gastric injury, and the underlying molecular mechanisms. The rat model of GI-R was established by clamping the celiac artery for 30 min and reperfusion for different hours (1, 3, and 6 h). The gastric injury was evaluated by hematoxylin and eosin staining of the stomach and the gastric mucosal index. The autophagy-lysosome dysfunction in the PVN was evaluated by the protein levels of LC3 II and Beclin-1 (markers for autophagosome activity) and the activity of acid phosphatase (a representative lysosomal enzyme). Immunohistochemical staining of ionized calcium-binding adaptor molecule 1 in the PVN was performed to evaluate microglial activation. Reactive oxygen species (ROS) content and phosphorylated γ-aminobutyric acid B receptor (p-GABA_B R) expression in the PVN were also examined. The results revealed that, in GI-R rats, the shorter the reperfusion duration, the more severe the gastric mucosal damage. The autophagy-lysosome dysfunction exhibited by GI-R rats further enhanced microglial activation, ROS production, p-GABA_B R expression, and gastric injury. In addition, activating microglial cells increased ROS production, p-GABA_B R expression, and gastric injury in GI-R rats, while inhibiting microglial activation resulted in the opposite results. Taken together, autophagy-lysosome dysfunction induced by GI-R aggravated the gastric injury by inducing microglia activation.

Korean Red Ginseng exerts anti-inflammatory and autophagy-promoting activities in aged mice

BACKGROUND

Korean Red Ginseng (KRG) is a traditional herb that has several beneficial properties including anti-aging, anti-inflammatory, and autophagy regulatory effects. However, the mechanisms of these effects are not well understood. In this report, the underlying mechanisms of anti-inflammatory and autophagy-promoting effects were investigated in aged mice treated with KRG-water extract (WE) over a long period.

METHODS

The mechanisms of anti-inflammatory and autophagy-promoting activities of KRG-WE were evaluated in kidney, lung, liver, stomach, and colon of aged mice using semi-quantitative reverse transcription polymerase chain reaction (RT-PCR), quantitative RT-PCR (qRT-PCR), and western blot analysis.

RESULTS

KRG-WE significantly suppressed the mRNA expression levels of inflammation-related genes such as interleukin (IL)-1β, IL-8, tumor necrosis factor (TNF)-α, monocyte chemoattractant protein-1 (MCP-1), and IL-6 in kidney, lung, liver, stomach, and colon of the aged mice. Furthermore, KRG-WE downregulated the expression of transcription factors and their protein levels associated with inflammation in lung and kidney of aged mice. KRG-WE also increased the expression of autophagy-related genes and their protein levels in colon, liver, and stomach.

CONCLUSION

The results suggest that KRG can suppress inflammatory responses and recover autophagy activity in aged mice.

Activation of AMPK/mTOR-driven autophagy and inhibition of NLRP3 inflammasome by saxagliptin ameliorate ethanol-induced gastric mucosal damage

AIMS

Saxagliptin, a selective/potent dipeptidyl peptidase-4 inhibitor, has revealed remarkable anti-inflammatory features in murine models of nephrotoxicity, hepatic injury, and neuroinflammation. However, its potential effect on ethanol-induced gastric mucosal injury has not been examined. Hence, the present work investigated the prospect of saxagliptin to attenuate ethanol-evoked gastric injury, with emphasis on the AMPK/mTOR-driven autophagy and NLRP3/ASC/caspase-1 pathway.

MATERIALS AND METHODS

In ethanol-induced gastropathy, the gastric tissues were examined by immunohistochemistry, immunoblotting, histopathology, and ELISA.

KEY FINDINGS

The results demonstrated that saxagliptin (10 mg/kg; by gavage) suppressed the gastric pathological signs (area of gastric ulcer and ulcer index scores), histopathologic aberrations/damage scores, without provoking hypoglycemia in rats. These protective features were attributed to the enhancement of gastric mucosal autophagy flux, as proven with increased expression of LC3-II and Beclin 1, decreased accumulation of p62 SQSTM1, and activation of the autophagy-linked AMPK/mTOR pathway by increasing the expression of p-AMPK/AMPK and decreasing the expression of the autophagy suppressor p-mTOR/mTOR signal. In tandem, saxagliptin counteracted the ethanol-induced pro-apoptotic events by downregulating Bax, upregulating Bcl2 protein, and lowering the Bax/Bcl2 ratio. Equally important, saxagliptin suppressed the NLRP3 inflammasome in the gastric tissue by lowering the expression of NLRP3, ASC, and nuclear NF-κBp65, decreasing the activity of caspase-1, and diminishing the IL-1β levels. In the same regard, saxagliptin suppressed the mucosal oxidative stress by lowering lipid peroxide levels, increasing GSH and GPx antioxidants, and activating Nrf2/HO-1 pathway.

SIGNIFICANCE

Saxagliptin may be a promising intervention against ethanol-evoked gastropathy by activating AMPK/mTOR-driven autophagy and inhibiting NLRP3 inflammasome.

Autophagy in Gastric Mucosa: The Dual Role and Potential Therapeutic Target

The incidence of stomach diseases is very high, which has a significant impact on human health. Damaged gastric mucosa is more vulnerable to injury, leading to bleeding and perforation, which eventually aggravates the primary disease. Therefore, the protection of gastric mucosa is crucial. However, existing drugs that protect gastric mucosa can cause nonnegligible side effects, such as hepatic inflammation, nephritis, hypoacidity, impotence, osteoporotic bone fracture, and hypergastrinemia. Autophagy, as a major intracellular lysosome-dependent degradation process, plays a key role in maintaining intracellular homeostasis and resisting environmental pressure, which may be a potential therapeutic target for protecting gastric mucosa. Recent studies have demonstrated that autophagy played a dual role when gastric mucosa exposed to biological and chemical factors. More indepth studies are needed on the protective effect of autophagy in gastric mucosa. In this review, we focus on the mechanisms and the dual role of various biological and chemical factors regulating autophagy, such as Helicobacter pylori, virus, and nonsteroidal anti-inflammatory drugs. And we summarize the pathophysiological properties and pharmacological strategies for the protection of gastric mucosa through autophagy.

Autophagic Heterogeneity in Gastric Adenocarcinoma

Background and Aim

Gastric/gastroesophageal junction (GEJ) adenocarcinoma is a heterogeneous disease, with various etiologies and with tumors encompassing a spectrum of histologic and molecular subtypes. "Autophagy" includes two related but distinct homeostatic processes that promote cell survival under adverse conditions, namely macro- and chaperone-mediated autophagy. There is increasing evidence of the roles autophagy may play in tumorigenesis.

Methods

Autophagic pathways were examined in the context of the heterogeneity intrinsic to gastric/GEJ adenocarcinoma, utilizing immunohistochemistry targeting specific proteins within the pathways (p62, LAMP2A, LC3B). We examined whole sections of normal and dysplastic gastric mucosa, as well as a tissue microarray of adenocarcinomas.

Results

Dysplastic gastric epithelium was marked by frequent nuclear p62 and aberrant LAMP2A expression compared to normal. Examining the pattern of LC3B/cytoplasmic p62 immuno-reactivity in gastric adenocarcinoma demonstrated a predominant pattern of LC3B^High/p62^High staining (56/86, 65.1%), which has been previously associated with active, but impaired macroautophagy. There were no statistically significant associations seen between LC3B/cytoplasmic p62 staining patterns with tumor grade, histotype, or approximated TCGA molecular subtype. LAMP2A and nuclear p62 and staining patterns were also heterogeneous across the cohort, but with no statistically significant associations seen. The prognostic significance of the three proteins was limited, however high nuclear p62 levels were associated with worse overall survival (log-rank p-value = 0.0396).

Conclusion

Our data demonstrate the dynamic nature of autophagic proteins in the gastric epithelium, and we expand the biological heterogeneity observed in gastric/GEJ adenocarcinoma to include autophagy.

Geranium koreanum, a medicinal plant Geranii Herba, ameliorate the gastric mucosal injury in gastritis-induced mice

ETHNOPHARMACOLOGICAL RELEVANCE

Geranii Herba, the traditional medicinal plants Korean and northeast China, has been used in the healing of a variety of gastrointestinal inflammation disorders. Geranium koreanum is a congeneric origin plant of Geranii Herba that can be used as medicinal plants with Geranium thunbergii, Geranium sibiricum, Geranium carolinianum, Geranium nepalense, and Geranium japonicam. However, research on the biological activity of Geranium koreanum is currently insufficient.

AIM OF THE STUDY

Gastritis is typically characterized by inflammation and irritation, and it is commonly caused by factors such as stress, alcohol consumption, smoking, and the use of anti-inflammatory drugs. In particular, excessive ethanol ingestion is an important cause of gastric disease mediated by mucosal damage by inflammatory cells infiltration. In this study, we investigated whether Geranium koreanum, the well-known traditional medicinal plant, could have a protective effect on gastric mucosal damage in an HCl/EtOH-induced gastritis model by analyzing the inflammation response in gastric tissue.

MATERIAL AND METHODS

The cytotoxicity and anti-inflammatory effects of Geranium koreanum were analyzed by determining cell viability and nitric oxide (NO) production, as well as the levels of nuclear factor (NF)-κB proteins in lipopolysaccharide (LPS)-induced cells. Additionally, we measured the damage ratio, conducted histopathological assay by H&E and PAS staining, and determined the levels of pro-inflammation mediator proteins in gastric tissue after induction of gastritis by HCl/EtOH administration in order to analyze the gastro-protective effects of Gerranium koreanum.

RESULTS

The ulcer ratio and inflammatory cell infiltration in gastric mucosa were reduced by treatment with Geranium koreanum. Additionally, the expression of inflammatory mediators in gastric tissue was effectively decreased by extracts administrated at 200 mg/kg, as compared to the gastritis control.

CONCLUSIONS

We demonstrated that Geranium koreanum could have ameliorating effects against HCl/EtOH-induced gastritis through the anti-inflammatory response, which indicates the potential use of this plant as a natural preventive medicine for gastritis treatment.

Polysaccharides of Dendrobium officinale Kimura & Migo Leaves Protect Against Ethanol-Induced Gastric Mucosal Injury via the AMPK/mTOR Signaling Pathway in Vitro and vivo

Ethanol-induced gastric mucosal injury is a common gastrointestinal disorder. Polysaccharides separated from herbs have been shown to be effective for ethanol-induced gastric mucosal injury, but whether the polysaccharides from Dendrobium officinale Kimura & Migo leaves (LDOP-1) protected mucosa from ethanol-induced injury remains unknown. Thus, the present study carried out gastric mucosal protection and the mechanism of LDOP-1 in vivo and vitro. The chemical composition of LDOP-1 was a heteropolysaccharide comprising mannose, galacturonic acid, glucose, galactose, and arabinose at a molar ratio of 2.0:1.1:0.7:0.5:0.4. Pharmacological results showed that LDOP-1 significantly reduced gastric mucosal injury score and pathological injury, improved antioxidant capacity, reduced the level of reactive oxygen species, and reversed the apoptosis of GES-1 in vivo and vitro. Research showed that LDOP-1 pretreatment upregulated the expression level of p-AMPK, LC3β, HO-1, and Beclin-1; downregulated the expression level of p-mTOR and p62; and reversed the expression level of caspase3, Bax, and Bcl-2. This study was the first to demonstrate that LDOP-1 could protect against ethanol-induced gastric mucosal injury via the AMPK/mTOR signaling pathway in vitro and vivo.

Indomethacin can induce cell death in rat gastric parietal cells through alteration of some apoptosis- and autophagy-associated molecules

In clinical medicine, indomethacin (IND, a non-steroidal anti-inflammatory drug) is used variously in the treatment of severe osteoarthritis, rheumatoid arthritis, gouty arthritis or ankylosing spondylitis. A common complication found alongside the therapeutic characteristics is gastric mucosal damage. This complication is mediated through apoptosis and autophagy of the gastrointestinal mucosal epithelium. Apoptosis and autophagy are critical homeostatic pathways catalysed by caspases downstream of the gastrointestinal mucosal epithelial injury. Both act through molecular signalling pathways characterized by the initiation, mediation, execution and regulation of the cell regulatory cycle. In this study we hypothesized that dysregulated apoptosis and autophagy are associated with IND-induced gastric damage. We examined the spectra of in vivo experimental gastric ulcers in male Sprague-Dawley rats through gastric gavage of IND. Following an 18-hour fast, IND was administered to experimental rats. They were sacrificed at 3-, 6- and 12-hour intervals. Parietal cells (H⁺ , K⁺ -ATPase β-subunit assay) and apoptosis (TUNEL assay) were determined. The expression of apoptosis-signalling caspase (caspases 3, 8, 9 and 12), DNA damage (anti-phospho-histone H2A.X) and autophagy (MAP-LC3, LAMP-1 and cathepsin B)-related molecules in gastric mucosal cells was examined. The administration of IND was associated with gastric mucosal erosions and ulcerations mainly involving the gastric parietal cells (PCs) of the isthmic and upper neck regions and a time-dependent gradual increase in the number of apoptotic PCs with the induction of both apoptotic (upregulation of caspases 3 and 8) cell death and autophagic (MAP-LC3-II, LAMP-1 and cathepsin B) cell death. Autophagy induced by fasting and IND 3 hours initially prompted the degradation of caspase 8. After 6 and 12 hours, damping down of autophagic activity occurred, resulting in the upregulation of active caspase 8 and its nuclear translocation. In conclusion we report that IND can induce time-dependent apoptotic and autophagic cell death of PCs. Our study provides the first indication of the interactions between these two homeostatic pathways in this context.

Ultra-structural study of the indomethacin-induced apoptosis and autophagy in rat gastric parietal cells

BACKGROUND AND AIM OF THE WORK

Indomethacin (IND), a non-steroidal anti-inflammatory drug, can induce gastric mucosal ulcerations. To date, the ultra-structural changes in the parietal cells (PCs) of the gastric mucosa following the intake of IND are mostly unknown. We carried out the current investigation to get insights into this issue.

MATERIALS AND METHODS

We established an animal model consisting of 35 adult male Sprague Dawley rats. The animals were divided into three groups, including; control (normal feeding), fasting, and indomethacin-treated groups. After treatment of 18-h fasting rats with IND, they were sacrificed at 3, 6, and 12-h intervals. The morphological features, including the apoptotic, and autophagic changes in the gastric mucosa PCs were examined using transmission electron microscopy.

RESULTS

In normal feeding animals (control group), the gastric PCs were present in various stages of activity. Fasting was associated with the predominance of the inactive parietal cells with features of up-regulated autophagy. In the IND -treated animals (at 3-h interval), PCs showed prominent autophagic changes, and subtle apoptotic cell death. In the IND -treated animals (at 6-12-h interval), PCs showed prominent apoptotic changes, and subtle autophagic features.

CONCLUSIONS

Our study indicates that IND treatment could induce gastropathy through time-dependent alterations in the autophagic and apoptotic machinery of PCs. Further studies are needed to examine the underlying molecular mechanisms.

Caffeine Potentiates Ethanol-Induced Neurotoxicity Through mTOR/p70S6K/4E-BP1 Inhibition in SH-SY5Y Cells

Caffeine is a popular psychostimulant, which is frequently consumed with ethanol. However, the effects of caffeine on neuronal cells constantly exposed to ethanol have not been investigated. Apoptosis and oxidative stress occurring in ethanol-induced neurotoxicity were previously associated with decreased phosphorylation of the mTOR/p70S6K/4E-BP1 signaling proteins. Evidence also suggested that caffeine inhibits the mTOR pathway. In this study, human SH-SY5Y neuroblastoma cells were exposed to caffeine after pretreatment for 24 hours with ethanol. Results indicated that both ethanol and caffeine caused neuronal cell death in a dose- and time-dependent manner. Exposure to 20-mM caffeine for 24 hours magnified reduced cell viability and enhanced apoptotic cell death induced by 200 mM of ethanol pretreatment. The phosphorylation of mTOR, p70S6K, and 4E-BP1 markedly decreased in cells exposed to caffeine after ethanol pretreatment, associated with a decrease of the mitochondrial membrane potential (ΔΨm). These findings suggested that caffeine treatment after neuronal cells were exposed to ethanol resulted in marked cell damages, mediated through enhanced inhibition of mTOR/p70S6K/4E-BP1 signaling leading to impaired ΔΨm and, eventually, apoptotic cell death.

Prophylactic effect of Lactobacillus plantarum KSFY06 on HCl/ethanol-induced gastric injury in mice

The present study was conducted to determine the prophylactic effect of Lactobacillus plantarum KSFY06 (LP-KSFY06) on HCl/ethanol-induced gastric injury in Kunming mice.

Preventive Effect of Anji White Tea Flavonoids on Alcohol-Induced Gastric Injury through Their Antioxidant Effects in Kunming Mice

Anji white tea (Camellia sinensis) is a traditional Chinese tea beverage, which is classified as green tea and contains an abundant amount of flavonoids. In this study, the preventive effect of Anji white tea flavonoids (AJWTFs) on ethanol/hydrochloric acid-induced gastric injury in mice was evaluated. The serum and gastric tissues of mice were analyzed using a biochemical kit and by quantitative polymerase chain reaction (qPCR). Observation of the appearance of the stomach indicated that AJWTFs could effectively reduce the area of gastric injury caused by ethanol/hydrochloric acid, and the inhibition rate of AJWTF on gastric injury increased with an increase in AJWTF concentration. The Anji white tea flavonoids could also reduce the volume and pH of gastric juice in mice with gastric injury. Biochemical results showed that AJWTFs could increase the superoxide dismutase (SOD) and glutathione (GSH) activities, as well as decrease the malondialdehyde (MDA) level, in the serum and liver of mice with gastric injury. Pathological observation confirmed that AJWTFs could inhibit the tissue damage caused by ethanol/hydrochloric acid in the stomach of mice. Further qPCR experiments also showed that AJWTFs could inhibit the decreases in neuronal nitric oxide synthase (nNOS), endothelial nitric oxide synthase (eNOS), copper/zinc superoxide dismutase (Cu/Zn–SOD), manganese superoxide dismutase (Mn–SOD), catalase (CAT), and the increase in inducible nitric oxide synthase (iNOS) expression in the gastric tissue of mice caused by gastric injury. As observed, AJWTFs exerted a good preventive effect on alcohol-induced gastric injury in mice induced by ethanol/hydrochloric acid, and the effect is close to that of ranitidine. Anji white tea flavonoids present good antioxidant effect, which allows them to effectively prevent alcoholic gastric injury and be used as biologically active substances with a broad range of applications.

Protective effect of silkworm pupa oil on hydrochloric acid/ethanol-induced gastric ulcers

BACKGROUND

Silkworm pupae are a traditional Chinese food, rich in various saturated and unsaturated fatty acids. Unsaturated fatty acids have a certain protective effect against oxidative damage. The present study used an animal model to determine the protective effect of silkworm pupa oil on hydrochloric acid / ethanol-induced gastric ulcer.

RESULTS

Silkworm pupa oil is rich in unsaturated fatty acids, including palmitoleic acid 63.4 g kg^-1 , oleic acid 249.1 g kg^-1 , linoleic acid 47.0 g kg^-1 , and linolenic acid 337.8 g kg^-1 , whereas its unsaturated fatty acid content is 700 g kg^-1 . Compared to a gastric ulcer control group, high and low doses of pupa oil reduced gastric ulcer area and gastric secretion, whereas gastric pH increased. It also increased serum antioxidant superoxide dismutase (SOD), catalase (CAT), glutathione peroxidase (GSH-Px) levels, somatostatin (SST), and vasoactive intestinal peptide (VIP) levels, and reduced serum interleukin-6 (IL-6), interleukin-12 (IL-12), tumor necrosis factor (TNF-α), and interferon-γ (IFN-γ), motilin (MTL), and gastrin (GT) levels. RT-qPCR and western blot analyses indicated that silkworm pupa oil significantly increased CAT, GSH-Px, epidermal growth factor (EGF), Epidermal growth factor receptor (EGFR), vascular endothelial growth factor (VEGF), endothelial nitric oxide synthase (eNOS), Cu/Zn-SOD, Mn-SOD, and NF-kappa-B inhibitor-α (IκB-α) expression and lowered nuclear factor-kappa B (NF-κB), B-cell lymphoma-2 (Bcl-2), cyclooxygenase-2 (COX-2), and inducible nitric oxide synthase (iNOS) expression.

CONCLUSION

Silkworm pupa oil treatment reduced oxidative damage and inflammation in mice, and high-dose silkworm pupa oil was superior to low-dose silkworm pupa oil, following ranitidine. © 2018 Society of Chemical Industry.

Modulation of autophagy in human diseases strategies to foster strengths and circumvent weaknesses

Autophagy is central to the maintenance of intracellular homeostasis across species. Accordingly, autophagy disorders are linked to a variety of diseases from the embryonic stage until death, and the role of autophagy as a therapeutic target has been widely recognized. However, autophagy-associated therapy for human diseases is still in its infancy and is supported by limited evidence. In this review, we summarize the landscape of autophagy-associated diseases and current autophagy modulators. Furthermore, we investigate the existing autophagy-associated clinical trials, analyze the obstacles that limit their progress, offer tactics that may allow barriers to be overcome along the way and then discuss the therapeutic potential of autophagy modulators in clinical applications.

Ethanol-induced cognitive dysfunction is associated with alterations in the mammalian target of rapamycin signalling pathway in the hippocampus of male mice

The aim of the present study is to investigate the effect of acute excessive administration of ethanol on the expression of proteins related to the PI3K/Akt/mTOR signalling pathway in the mouse hippocampus and to reveal the possible molecular mechanism of learning and memory deficits induced by ethanol. A total of 120 8-week-old Kunming mice (half male and half female) were randomly assigned into low-dose, moderate-dose, and high-dose male and female groups with intragastric administration of 12.5, 25 and 50% ethanol, respectively, at the dosage of 0.1 ml/10 g·day for 14 days. The male and female control groups received an equal volume of distilled water. Then, the spatial learning and memory of the mice were evaluated by the Morris water maze task. The expression of p-mTOR, p-Akt, mTOR and Akt proteins was tested by western blotting and immunohistochemical staining methods in the hippocampal formation in each group, and haematoxylin-eosin stain was used to identify morphological changes in the hippocampal region. Our results indicated that 25 and 50% ethanol administration led to cognitive dysfunction and hippocampal pyramidal cell impairment in the female and male mice, with the male mice showing more severe impairment. In the 50% ethanol group, the male mice exhibited low expression levels of p-Akt and p-mTOR, but the female mice had no significant differences compared with the respective control group. Interestingly, the male expression levels of p-Akt and p-mTOR were significantly lower than those of females. Overall, these findings suggested that the cognitive deficits induced by ethanol are more serious in male mice than in female mice, and the PI3K/Akt/mTOR signalling pathway in the hippocampus might be involved in the impairment process.

Genome-wide sequence and expressional analysis of autophagy Gene family in bread wheat (Triticum aestivum L.)

Autophagy, a highly conserved intracellular degradation system, is regarded to be responsible for self-defense and protect cells from abiotic stress. Extensive studies have demonstrated that autophagy plays a crucial role in regulating plant growth and development as well as in response to diverse stresses. However, little is known about autophagy-associated genes (ATGs) in wheat, especially those involved in the regulatory network of stress processes. In this study, a total of 108 putative wheat ATGs (TaATG) were obtained based on a genome-wide search approach. Phylogenetic analysis classified them into 13 subfamilies, of which the TaAtg16 subfamily consisted of 29 members, ranking it the largest subfamily. The conserved motif compositions as well as their exon-intron structures were systematically analyzed and strongly supported the classification. The homoeologous genes tended to have similar gene features during wheat polyploidization. Furthermore, a total of 114 putative cis-elements were found, and those related to hormone, stress, and light responsiveness were abundantly presented in the promoter regions. Co-expression network analysis revealed that orthologous VAMP727 was the hub node of the whole network, and complex interactions were also found. Finally, the expression profiles of TaATGs among different tissues and under abiotic stresses were investigated to identify tissue-specific or stress-responsive candidates, and then 14 were validated by wet-lab analysis. Results showed that the TaAtg8 subfamily played a crucial role in tissue autophagy and stress defense, which could be considered as processes that are candidates for further functional study. This was the first study to comprehensively investigate the ATG family in wheat, which ultimately provided important clues for further functional analysis and also took a step toward uncovering the evolutionary mechanism of ATG genes in wheat and beyond.

Theaflavins attenuate ethanol‑induced oxidative stress and cell apoptosis in gastric mucosa epithelial cells via downregulation of the mitogen‑activated protein kinase pathway

Ethanol‑induced diseases of the gastric mucosa are the most common and refractory diseases of gastrointestinal system in clinic, and are mediated by oxidative stress and apoptosis pathways. Theaflavins (TFs) are considered to be antioxidants. The present study aimed to determine the molecular mechanism underlying the ability of TFs to attenuate ethanol‑induced oxidative stress and apoptosis in GES‑1 gastric mucosa epithelial cells. A Cell Counting Kit‑8 (CCK‑8) assay was performed to investigate the cell viability of GES‑1 cells following administration of ethanol (0.5 mol/l) and subsequent treatment with TFs (20, 40 and 80 µg/ml) for specific time intervals. A carboxyfluorescein diacetate succinimidyl ester assay was used to measure proliferation and further investigate the results of the CCK‑8 assay. Flow cytometry was performed to measure reactive oxygen species (ROS) levels and the apoptosis rates of GES‑1 cells. Furthermore, levels of oxidative stress‑associated factors, including malondialdehyde, superoxide dismutase and glutathione, were investigated using commercial kits. Reverse transcription‑quantitative polymerase chain reaction and western blot assays were performed to determine the expression levels of apoptosis‑associated factors, as well as the phosphorylation levels of extracellular signal‑regulated kinase (ERK), c‑Jun N‑terminal kinase (JNK) and p38 kinase (p38). The results of the present study demonstrated that treatment with ethanol inhibited GES‑1 cell proliferation, and enhanced ROS levels and apoptosis rates, potentially via downregulation of B‑cell lymphoma‑2 (Bcl‑2) expression and upregulation of Bcl‑2‑associated X and caspase‑3 expression levels, as well as enhancing the phosphorylation levels of ERK, JNK and p38. However, treatment with TFs was revealed to attenuate the effects of ethanol administration on GES‑1 cells in a dose‑dependent manner. In conclusion, TFs may attenuate ethanol‑induced oxidative stress and apoptosis in gastric mucosa epithelial cells via downregulation of various mitogen‑activated protein kinase pathways.