Activating Transcription Factor 6 Mediates Inflammatory Signals in Intestinal Epithelial Cells Upon Endoplasmic Reticulum Stress

Dietary resveratrol alleviates liver and intestinal injury in ducks under cage rearing system

Cage rearing is a promising farming method. However, our previous studies have demonstrated that changes in farming practices induce oxidative stress and inflammation in the liver and duodenum of ducks. Resveratrol (RES), a natural plant polyphenol, possesses antioxidant, anti-inflammatory, and cytoprotective properties. This study evaluated the alleviating effects of RES against cage-rearing-induced duck health problems, emphasizing the involvement of redox imbalance, inflammatory response, endoplasmic reticulum (ER) stress, apoptosis, and PI3K/AKT and MAPK/ERK pathways. A total of 120 healthy 12-week-old female ducks were transferred to a cage system and randomly assigned to two dietary RES groups with 6 replicates each (10 ducks per replicate), including basal diet + 0 mg/kg RES (control group, CON), and basal diet + 500 mg/kg RES (RES-treated group, RES). During the early stages (within 10 days) of cage rearing, blood, liver, and duodenal samples were collected for analysis. The results demonstrated that RES reduced histopathological damage in the liver and duodenum of cage-reared ducks. It also reduced serum albumin levels, increased serum aspartate aminotransferase and alanine aminotransferase levels, and enhanced antioxidant (increased CAT, GSH-Px, SOD, and T-AOC activities in the serum, liver, and duodenum, and reduced the increase in MDA) and anti-inflammatory properties (reduced pro-inflammatory cytokines interleukin (IL)-1β and IL-6 secretion and increased anti-inflammatory cytokine IL-4 levels). Additionally, quantitative real-time polymerase chain reaction revealed that RES intervention reversed the abnormal mRNA abundance of biomarkers associated with inflammatory injury (iNOS and COX2) in the liver, and ER stress (GRP78) and apoptosis (Bax and Bcl2) in the liver and duodenum of cage-reared ducks. Further analysis of key proteins in the PI3K/AKT and ERK MAPK signaling pathways revealed that RES promoted AKT phosphorylation in the liver and duodenum of cage-reared ducks and reduced cleaved caspase-3 protein content. Overall, RES prevents cage-rearing stimuli-induced liver and intestinal injury in ducks by enhancing liver function, improving antioxidant properties, inhibiting inflammation, ER stress, and apoptosis, and activating the PI3K/AKT signaling pathway.

Therapeutic application of nano-encapsulated pomegranate peel extract attenuated DSS-induced colitis: Antioxidant and anti-inflammatory role and reduction of exaggerated response of endoplasmic reticulum stress

The medicinal application of pomegranate peel extract enriched with polyphenols (PPE) as a therapeutic strategy for managing inflammatory bowel diseases (IBD) is still limited. Integrating pomegranate peel extract (PPE) into an effective nanocarrier system could enhance its mechanistic actions, potentially aiding in the remission of colitis. Therefore, this approach aimed to enhance PPE's stability and bioavailability and investigate mitigating impact of pomegranate peel extract-loaded nanoparticles (PPE-NPs) in a colitis model. Colonic injury was induced by 5% dextran sulfate sodium (DSS) and efficacy of disease progression after oral administration of PPE-NPs for 14 days was assessed by evaluating clinical signs severity, antioxidant and inflammatory markers, expressions of endoplasmic reticulum associated genes and histopathological and immunostaining analysis in colonic tissues. Clinical signs and disease activity index were effectively reduced, and the levels of fecal calprotectin were decreased in groups treated with PPE-NPs compared to DSS group. The colitic group showed a significant increase (P < 0.05) in C-reactive protein (CRP) and myeloperoxidase (MPO) and nitric oxide (NO) (35.60, 163.30 and 280 nmol/g tissue respectively) and higher expression (P < 0.05) IL-17, TNF-α, and IL-1β (increased up to 2.99, 4.36 and 4.90 respectively unlike PPE-NPsIII that recorded reduced levels of CRP, MPO and NO (8,96, 78.30 and 123 nmol/g tissue respectively) and much lower (P < 0.05) levels of IL-17, TNF-α, and IL-1β expression (decreased to 1.23, 1.69 and 1.64, respectively). The most improvement of colon damage PPE-NPsIII group was also associated with the reduction MDA level (P < 0.05) (decreased to 21.60 vs 90.65 in DSS non treated group). The highest glutathione peroxidase, superoxide dismutase and catalase activities were noted in PPE-NPsIII received group (42.60, 50.30 and 62.70 U/mg). Notably, prominent free radical scavenging activities were noticed in group received 150 mg/kg of PPE-NPs as supported by higher scavenging of 1,1-diphenyl-2-picrylhydrazyl (9.85 mg/g) and 2,2-azinobis-(3-ethylbenzothiazoline-6-sulfonic acid tested radicals (19.98 mg/g). Balancing between endoplasmic reticulum stressors (ERS), inflammation and autophagy was prominently noted in group treated with 150 mg/kg of PPE-NPs. These findings were supported by subsiding the excessive expression of ERS related genes (CHOP, JUNK, ATF6, BIP, and Elf-2) and immunostaining expression regulation of key markers regulating autophagy (Beclin-2) in this group. The histopathological changes in the colon were less severe in the PPE-NPs received groups (especially at the level of 150 mg/kg) compared to DSS group. Collectively, these findings suggest that the nanoencapsulation of PPE enhances its effectiveness in promoting recovery of colonic tissue damage and achieving remission of colitis.

Gut microbiota modulate intestinal inflammation by endoplasmic reticulum stress-autophagy-cell death signaling axis

The intestinal tract, a complex organ responsible for nutrient absorption and digestion, relies heavily on a balanced gut microbiome to maintain its integrity. Disruptions to this delicate microbial ecosystem can lead to intestinal inflammation, a hallmark of inflammatory bowel disease (IBD). While the role of the gut microbiome in IBD is increasingly recognized, the underlying mechanisms, particularly those involving endoplasmic reticulum (ER) stress, autophagy, and cell death, remain incompletely understood. ER stress, a cellular response to various stressors, can trigger inflammation and cell death. Autophagy, a cellular degradation process, can either alleviate or exacerbate ER stress-induced inflammation, depending on the specific context. The gut microbiome can influence both ER stress and autophagy pathways, further complicating the interplay between these processes. This review delves into the intricate relationship between ER stress, autophagy, and the gut microbiome in the context of intestinal inflammation. By exploring the molecular mechanisms underlying these interactions, we aim to provide a comprehensive theoretical framework for developing novel therapeutic strategies for IBD. A deeper understanding of the ER stress-autophagy axis, the gut microbial-ER stress axis, and the gut microbial-autophagy axis may pave the way for targeted interventions to restore intestinal health and mitigate the impact of IBD.

Molecular Hydrogen Therapy: Mechanisms, Delivery Methods, Preventive, and Therapeutic Application

Molecular hydrogen (H2), recognized as the smallest gas molecule, is capable of permeating cellular membranes and diffusing throughout the body. Due to its high bioavailability, H2 is considered a therapeutic gas for the treatment of various diseases. The therapeutic efficacy of hydrogen is contingent upon factors such as the administration method, duration of contact with diseased tissue, and concentration at targeted sites. H2 can be administered exogenously and is also produced endogenously within the intestinal tract. A comprehensive understanding of its delivery mechanisms and modes of action is crucial for advancing hydrogen medicine. This review highlights H₂'s mechanisms of action, summarizes its administration methods, and explores advancements in treating intestinal diseases (e.g., inflammatory bowel disease, intestinal ischemia-reperfusion, colorectal cancer). Additionally, its applications in managing other diseases are discussed. Finally, the challenges associated with its clinical application and potential solutions are explored. We propose that current delivery challenges faced by H2 can be effectively addressed through the use of nanoplatforms; furthermore, interactions between hydrogen and gut microbiota may provide insights into its mechanisms for treating intestinal diseases. Future research should explore the synergistic effects of H2 in conjunction with conventional therapies and develop personalized treatment plans to achieve precision medicine.

Enterohemorrhagic Escherichia coli O157:H7 Infection Inhibits Host Endoplasmic Reticulum Stress in Intestinal Epithelial Cells via the PERK Pathway

Enterohemorrhagic Escherichia coli (EHEC) O157:H7 is a foodborne pathogen that causes a variety of diseases, ranging from self-limiting gastroenteritis to life-threatening extra-intestinal diseases such as hemolytic uremic syndrome. EspF, an effector protein secreted by the type III secretion system of EHEC, is primarily responsible for the development of inflammatory colitis. Our previous study revealed that EspF interacts with the host Annexin A6 (ANXA6) protein and targets the endoplasmic reticulum (ER). Given the critical effects of ER stress on the host responses of gastroenteritis, we explored the role of EspF-ANXA6 interaction in ER stress. Caco-2 cells were infected with different strains of EHEC and transfected with modified plasmids to establish in vitro research models. Our results revealed that infection with espF-deletion EHEC strains significantly exacerbated ER stress. Specifically, the phosphorylation of eIF2α was elevated, and the expression levels of BiP, ATF4, and CHOP were increased by more than 15% compared to those in cells infected with wild-type EHEC strains. Further experiments showed that EspF co-localizes with BiP and down-regulates the PERK pathway. Meanwhile, the EspF-ANXA6 interaction could aggravate the inhibition of the PERK pathway and stimulate calcium influx to disturb ER homeostasis, eventually leading to apoptosis. Our findings suggest that the EspF-ANXA6 interaction could inhibit ER stress through the PERK pathway, which may limit cell-to-cell communication and block the clearance of bacteria in host cells.

Molecular mechanisms of pyroptosis in non-alcoholic steatohepatitis and feasible diagnosis and treatment strategies

Pyroptosis is a distinct form of cell death that plays a critical role in intensifying inflammatory responses. It primarily occurs via the classical pathway, non-classical pathway, caspase-3/6/7/8/9-mediated pathways, and granzyme-mediated pathways. Key effector proteins involved in the pyroptosis process include gasdermin family proteins and pannexin-1 protein. Pyroptosis is intricately linked to the onset and progression of non-alcoholic steatohepatitis (NASH). During the development of NASH, factors such as pyroptosis, innate immunity, lipotoxicity, endoplasmic reticulum stress, and gut microbiota imbalance interact and interweave, collectively driving disease progression. This review analyzes the molecular mechanisms of pyroptosis and its role in the pathogenesis of NASH. Furthermore, it explores potential diagnostic and therapeutic strategies targeting pyroptosis, offering new avenues for improving the diagnosis and treatment of NASH.

Distribution of epithelial endoplasmic reticulum stress-related proteins in adult and pediatric Crohn's disease: Association with inflammation and fibrosis

BACKGROUND/AIMS

Intestinal strictures in Crohn's disease (CD), driven by fibrosis remain challenging to treat. Current treatments focus on inflammation, but are less effective against fibrosis. Endoplasmic Reticulum Stress-Related Proteins, including Protein disulfide isomerases (PDIs), may contribute to fibrosis; their roles in CD remain unclear. This study investigated the distribution of AGR2, BiP, PDIA6, ERP44 in intestinal epithelium and their association with fibrosis and inflammation in pediatric and adult CD.

METHODS

We retrospectively analyzed 224 patients (2009-2023). CD patients with and without strictures, non IBD controls, and ulcerative colitis patients were compared. Immunohistochemistry assessed Endoplasmic Reticulum Stress-Related protein distribution in epithelium. H&E and Masson's trichrome staining evaluated inflammation and fibrosis. Correlations between protein distribution, inflammation and fibrosis were examined.

RESULTS

AGR2 and BiP were increased in fibro-inflammatory and fibrotic intestinal epithelial tissues, especially in pediatric-onset CD. ERP44 was associated with fibrosis exclusively in pediatric CD. PDIA6 was upregulated in CD compared to non IBD, without fibrosis association. Distinct protein distribution patterns were observed between pediatric and adult CD, and between ileum and colon.

CONCLUSIONS

Distinct patterns of AGR2, BiP, PDIA6, and ERP44 in fibrotic and inflammatory intestinal tissues suggest potential roles in CD-associated fibrosis, warranting exploration as biomarkers or therapeutic targets.

Luteolin Modulate Endoplasmic Reticulum Stress by Targeting SIRT1 to Ameliorate DSS-Induced Ulcerative Colitis in Mice

Ulcerative colitis (UC) is a recurrent, chronic disease whose main symptoms include weight loss, diarrhea, and blood in the stool. In recent years, the incidence of UC has been increasing year by year, which seriously affects the daily life of patients. Luteolin (Lut), as a flavonoid, is widely found in a variety of vegetables and fruits and has been shown to have a variety of pharmacological activities. This work investigated the effects of Lut on dextrose sodium sulfate (DSS)-induced ulcerative colitis (UC) in mice, with a special focus on the role of endoplasmic reticulum (ER) stress in this. The outcomes demonstrated that colitis symptoms, including disease phenotype, elevated inflammatory factor levels, intestinal barrier damage, and gut microbiota disruption, were considerably alleviated in UC model mice treated with luteolin. Also, Lut alleviated ER stress and apoptosis in UC mice. We then explored the effects of Lut on ER stress and apoptosis induced by thapsigargin (TG) and tunicamycin (TM) in HT29 cells in vitro. It was found that Lut treatment inhibited TM/TG-induced ER stress and apoptosis. However, these inhibitory effects of Lut were attenuated by SIRT1 silencing in TM-treated HT29 cells. In conclusion, our results suggest that Lut supplementation in a mouse model of colitis improves the symptoms of colitis in mice, which provides a theoretical basis for further application of Lut in the prevention of inflammation-related diseases in humans.

Endoplasmic reticulum stress in gut inflammation: Implications for ulcerative colitis and Crohn's disease

Eukaryotic cells contain the endoplasmic reticulum (ER), a prevalent and intricate membranous structural system. During the development of inflammatory bowel disease (IBD), the stress on the ER and the start of the unfolded protein response are very important. Some chemicals, including 4μ8C, small molecule agonists of X-box binding protein 1, and ISRIB, work on the inositol-requiring enzyme 1, turn on transcription factor 6, and activate protein kinase RNA-like ER kinase pathways. This may help ease the symptoms of IBD. Researchers investigating the gut microbiota have discovered a correlation between ER stress and it. This suggests that changing the gut microbiota could help make new medicines for IBD. This study looks at how ER stress works and how it contributes to the emergence of IBD. It also talks about its possible clinical importance as a therapeutic target and looks into new ways to treat this condition.

Paricalcitol alleviates intestinal ischemia-reperfusion injury via inhibition of the ATF4-CHOP pathway

Introduction

Intestinal ischemia reperfusion (I/R) injury is a severe condition characterized by inflammation, oxidative stress, and compromised intestinal barrier function, which can lead to death. This study investigated the effects of paricalcitol, a synthetic vitamin D receptor (VDR) agonist, on intestinal I/R injury, focusing on the activating transcription factor 4 (ATF4)-C/EBP homologous protein (CHOP) signaling pathway and the modulation of endoplasmic reticulum stress (ERS).

Methods

This study consists of both in vivo and in vitro experiments. In vivo experiment, a mouse model of intestinal I/R injury was established by clamping the superior mesenteric artery, and followed by 24 or 72 h of reperfusion. 6-week-old male C57BL/6 J mice were randomly assigned to six groups: sham, I/R 24h, I/R 72 h, and their respective paricalcitol-treated counterparts. VDR knockout mice and wild-type mice were assigned to WT, VDR-KO, WT + I/R and VDR-KO + I/R groups. The paricalcitol-treated groups received oral gavage of paricalcitol (0.3 μg/kg) once daily for 5 days before I/R. In vitro, IEC-6 cells were incubated in a microaerophilic system (5% CO2, 1% O2, 94% N2) for 6 h to induce hypoxia. The cells were then transferred to complete medium with or without paricalcitol (200 nM) and cultured under normoxic conditions for 24 h to establish the hypoxia/re-oxygenation (H/R) model and investigate the protective effects of paricalcitol on H/R-induced injury in cells. We further utilized VDR- and ATF4-silenced cells to examine how paricalcitol regulates the expression of VDR, ATF4, and CHOP.

Results

We demonstrated that protective paricalcitol treatment reduces ERS and apoptosis by activating VDR and inhibiting the ATF4-CHOP pathway, thereby alleviating intestinal I/R injury in vivo and H/R injury in vitro. Furthermore, experiments with VDR knockout mice demonstrated that the absence of VDR exacerbated I/R injury, underscoring the protective role of VDR in intestinal epithelial cells.

Discussion

These findings suggest that the protective effects of paricalcitol may offer a promising therapeutic strategy for managing intestinal I/R injury.

Macrophage ATF6 accelerates corticotomy-assisted orthodontic tooth movement through promoting Tnfα transcription

Corticotomy is a clinical procedure to accelerate orthodontic tooth movement characterized by the regional acceleratory phenomenon (RAP). Despite its therapeutic effects, the surgical risk and unclear mechanism hamper the clinical application. Numerous evidences support macrophages as the key immune cells during bone remodeling. Our study discovered that the monocyte-derived macrophages primarily exhibited a pro-inflammatory phenotype that dominated bone remodeling in corticotomy by CX3CR1CreERT2; R26GFP lineage tracing system. Fluorescence staining, flow cytometry analysis, and western blot determined the significantly enhanced expression of binding immunoglobulin protein (BiP) and emphasized the activation of sensor activating transcription factor 6 (ATF6) in macrophages. Then, we verified that macrophage specific ATF6 deletion (ATF6f/f; CX3CR1CreERT2 mice) decreased the proportion of pro-inflammatory macrophages and therefore blocked the acceleration effect of corticotomy. In contrast, macrophage ATF6 overexpression exaggerated the acceleration of orthodontic tooth movement. In vitro experiments also proved that higher proportion of pro-inflammatory macrophages was positively correlated with higher expression of ATF6. At the mechanism level, RNA-seq and CUT&Tag analysis demonstrated that ATF6 modulated the macrophage-orchestrated inflammation through interacting with Tnfα promotor and augmenting its transcription. Additionally, molecular docking simulation and dual-luciferase reporter system indicated the possible binding sites outside of the traditional endoplasmic reticulum-stress response element (ERSE). Taken together, ATF6 may aggravate orthodontic bone remodeling by promoting Tnfα transcription in macrophages, suggesting that ATF6 may represent a promising therapeutic target for non-invasive accelerated orthodontics.

The Hsa_circ_0105558/miR-182-5p/ATF6 Cascade Affects H2O2-Triggered Oxidative Damage and Apoptosis of Human Lens Epithelial Cells

Age-related cataract (ARC) is the prevalent cause of useful vision loss. Circular RNAs are related to ARC pathogenesis partly through their competing endogenous RNA (ceRNA) activity. Herein, we defined the action of hsa_circ_0105558 in hydrogen peroxide (H2O2)-driven apoptosis and oxidative damage in human lens epithelial SRA01/04 cells. Hsa_circ_0105558, microRNA (miR)-182-5p and activating transcription factor 6 (ATF6) were evaluated by a qRT-PCR or immunoblotting method. The hsa_circ_0105558/miR-182-5p and miR-182-5p/ATF6 relationships were predicted by bioinformatics analysis and confirmed by dual-luciferase reporter assay. Reactive oxygen species level, glutathione peroxidase level, superoxide dismutase activity, and malondialdehyde level were measured using the matched assay kits. Hsa_circ_0105558 was upregulated in human ARC lens and H2O2-exposed SRA01/04 cells. Suppression of hsa_circ_0105558 attenuated H2O2-driven SRA01/04 cell apoptosis and oxidative damage. Hsa_circ_0105558 targeted miR-182-5p, and reduced miR-182-5p expression reversed the influence of hsa_circ_0105558 depletion on H2O2-driven oxidative damage and apoptosis. ATF6 was a target of miR-182-5p, and miR-182-5p-driven downregulation of ATF6 regulated cell oxidative damage and apoptosis under H2O2 insult. Moreover, hsa_circ_0105558 functioned as a ceRNA to post-transcriptionally control ATF6 expression through miR-182-5p competition. Our study demonstrates that hsa_circ_0105558 modulates SRA01/04 cell oxidative damage and apoptosis under H2O2 insult through the miR-182-5p/ATF6 cascade.

Endoplasmic Reticulum Stress in Acute Myeloid Leukemia: Pathogenesis, Prognostic Implications, and Therapeutic Strategies

Acute myeloid leukemia (AML) is a heterogeneous hematological malignancy that poses a significant therapeutic challenge due to its high recurrence rate and demanding treatment regimens. Increasing evidence suggests that endoplasmic reticulum (ER) stress and downstream activation of the unfolded protein response (UPR) pathway play a key role in the pathogenesis of AML. ER stress is triggered by the accumulation of misfolded or unfolded proteins within the ER. This causes activation of the UPR to restore cellular homeostasis. However, the UPR can shift from promoting survival to inducing apoptosis under prolonged or excessive stress conditions. AML cells can manipulate the UPR pathway to evade apoptosis, promoting tumor progression and resistance against various therapeutic strategies. This review provides the current knowledge on ER stress in AML and its prognostic and therapeutic implications.

Precision therapeutics for inflammatory bowel disease: advancing ROS-responsive nanoparticles for targeted and multifunctional drug delivery

Inflammatory bowel disease (IBD) is a severe chronic intestinal disorder with a rising global incidence. Current therapies, including the delivery of anti-inflammatory drugs and probiotics, face significant challenges in terms of safety, stability, and efficacy. In IBD patients, the activity of antioxidant enzymes (e.g., superoxide dismutase, glutathione peroxidase, and glutathione reductase) is reduced at the site of intestinal inflammation, leading to the accumulation of reactive oxygen species (ROS). This accumulation damages the intestinal mucosa, disrupts tight junctions between cells, and compromises the integrity of the intestinal barrier, exacerbating IBD symptoms. Therefore, nanoparticles responsive to ROS and capable of mimicking antioxidant enzyme activity, such as boronates, polydopamine, sulfides, and metal nanozymes, have emerged as promising tools. These nanoparticles can respond to elevated ROS levels in inflamed intestinal regions and release drugs to effectively neutralize ROS, making them ideal candidates for IBD treatment. This review discusses the application of various ROS-responsive nanomaterial delivery systems in IBD therapy, highlights current challenges, and outlines future research directions. Furthermore, we explore the "layered programmable delivery" strategy, which combines ROS-responsive nanoparticles with pH-responsive and cell membrane-targeted nanoparticles. This strategy has the potential to overcome the limitations of single-mechanism targeted drug delivery, enabling multi-range and multi-functional treatment approaches that significantly enhance delivery efficiency, providing new insights for the future of localized IBD treatment.

Unfolded protein response: An essential element of intestinal homeostasis and a potential therapeutic target for inflammatory bowel disease

Different physiological and pathological situations can produce alterations in the cell's endoplasmic reticulum (ER), leading to a condition known as ER stress, which can trigger an intricate intracellular signal transduction system known as the unfolded protein response (UPR). UPR is primarily tailored to restore proteostasis and ER equilibrium; otherwise, if ER stress persists, it can cause programmed cell death as a cytoprotective mechanism and drive inflammatory processes. Therefore, since intestinal cells strongly rely on UPR for their biological functions and unbalanced UPR has been linked to inflammatory, metabolic, and immune disorders, here we discussed the role of the UPR within the intestinal tract, focusing on the UPR contribution to inflammatory bowel disease development. Importantly, we also highlighted the promising potential of UPR components as therapeutic targets for intestinal inflammatory diseases.

Effects of orally exposed SiO2 nanoparticles on lipid profiles in gut-liver axis of mice

Recently we proposed the possibility of orally exposed nanoparticles (NPs) to alter metabolite homeostasis by changing metabolism pathways, in addition to intestinal damages, but relatively few studies investigated the changes of metabolite profiles in multi-organs. This study investigated the influences of orally exposed SiO2 NPs on lipid profiles in gut-liver axis. To this end, we treated mice with 16, 160 or 1600 mg/kg bodyweight SiO2 NPs via intragastric route. After 5 days exposure (once a day), we observed that SiO2 NPs induced minimal pathological changes but increased most of the trace elements. Furthermore, lipid staining was gradually decreased in intestines and livers with the increase of NP levels. Consistently, lipidomics results showed that most of the lipid classes in mouse intestines and livers were decreased following SiO2 NP administration. We further identified the lipid classes significantly decreased in both intestines and livers, such as phosphatidylserine (PS), phosphatidylglycerol (PG), and phosphatidylethanolamine (PE). Only a few lipid classes, such as anandamide, showed opposite trends in these organs. For metabolism pathway, SiO2 NPs suppressed autophagy, showing as a significant decrease of microtubule-associated protein 1 A/1B light chain 3 (LC3) and adipose triglyceride lipase (Atgl), accompanying with an accumulation of P62, in both intestines and livers. However, lysosomal-associated membrane protein 2 (Lamp2) showed different trend, that it was significantly increased in intestines but decreased in livers. Combined, our results indicated that intragastric administration of SiO2 NPs altered trace element balance and lipid profiles, accompanying with a change of autophagic lipolysis proteins, in mouse gut-liver axis.

Research progress and advances in endoplasmic reticulum stress regulation of acute kidney injury

Acute kidney injury (AKI) is a common and severe clinical disorder in which endoplasmic reticulum (ER) stress plays an important regulatory role. In this review, we summarize the research progress on the relationship between ER stress and AKI. It emphasizes the importance of maintaining a balance between promoting and protecting ER stress during AKI and highlights the potential of ER stress-targeted drugs as a new therapeutic approach for AKI. The article also discusses the need for developing drugs that target ER stress effectively while avoiding adverse effects on normal cells and tissues. The review concludes that with a more comprehensive understanding of ER stress mechanisms and advancements in research techniques, more effective treatment options for AKI can be developed in the future.

Involvement of ATF6 in Octreotide-Induced Endothelial Barrier Enhancement

Background/Objectives: Endothelial hyperpermeability is the hallmark of severe disease, including sepsis and acute respiratory syndrome (ARDS). The development of medical countermeasures to treat the corresponding illness is of utmost importance. Synthetic somatostatin analogs (SSA) are FDA-approved drugs prescribed in patients with neuroendocrine tumors, and they act via growth hormone (GH) suppression. Preclinical investigations suggest that Octreotide (OCT) alleviates Lipopolysaccharide (LPS)-induced injury. The aim of the study is to investigate the involvement of activating transcription factor 6 (ATF6) in the protective effects of OCT in endothelial dysfunction. To the best of our knowledge, the available information on that topic is limited. Methods: Human lung microvascular endothelial cells (HULEC-5a) and bovine pulmonary artery endothelial cells (BPAEC) which expressed elevated levels of ATF6 due to AA147 were exposed to OCT or vehicle. Protein expression, endothelial permeability, and reactive oxygen species (ROS) generation were assessed utilizing Western blot analysis, Fluorescein isothiocyanate (FITC)-Dextran assay, and Dichlorofluorescein diacetate measurements, respectively. Results: Our observations suggest that ATF6 activation significantly improves OCT-induced endothelial barrier enhancement. This combination led to increased expression of binding immunoglobulin protein (BiP) and glucose-regulated protein 94 (Grp94), which are downstream unfolded protein response (UPR) targets. Moreover, ATF6 activation prior to OCT treatment resulted in decreased activation of myosin light chain 2 (MLC2) and cofilin; and reduced reactive oxygen species (ROS) generation. ATF6 activation enhanced the anti-inflammatory effects of OCT, as reflected in the suppression of transducer and activator of transcription (STAT) 1, STAT3, and P38 phosphorylation. Conclusions: Our findings suggest that ATF6 activation prior to OCT treatment enhances the beneficial effects of OCT in the endothelium.

Activating Transcription Factor 6 Mediates Inflammation in Experimental Varicocele-Induced Epididymal Epithelial Cells

Introduction

Varicocele is a dilatation of the internal spermatic vein and it is generally recognized as one cause of male infertility. This study aimed to analyze the roles of activating transcription factor 6 (ATF-6) in experimental varicocele-induced epididymal epithelial cells.

Methods

Experimental left varicocele was established in rats through partial left renal vein ligation. At 8 weeks after surgery, the left epididymal damage was observed using H&E and TUNEL staining. The expressions of neutral α-glucosidase (NAG), ATF-6, tumor necrosis factor (TNF)-α, and phospho-nuclear factor (p-NF)-κB p65 (S536) in the left epididymis were measured by immunohistochemistry. ATF-6 silence in rat epididymal epithelial cells was established by ATF-6 siRNA transfection. The cells were treated with hypoxia for 24 h, and cell viability was measured by CCK-8, levels of NAG, TNF-α, and interleukin (IL)-8 in cells were measured by ELISA, levels of p-NF-κB p65 (S536)/NF-κB p65 protein in cells were measured by Western blotting.

Results

The results showed that the experimental left varicocele induced hypertrophy and apoptosis of epididymal epithelial cells (p<0.05), and decreased the expressions of NAG in the epididymal epithelial cells compared with the sham-operated control rats (p<0.01). Meanwhile, the expressions of ATF-6, TNF-α, and p-NF-κB p65 (S536) were increased in the epididymal epithelial cells after the experimental left varicocele compared with the sham-operated control rats (p<0.05). In the hypoxia-treated cells, ATF-6 silence increased the cell viability and decreased the levels of TNF-α, IL-8, and p-NF-κB p65 (S536) compared with the control cells (p<0.05).

Discussion

The ATF-6 pathway was activated in a rat's left varicocele-induced epididymal damage. Inhibition of the ATF-6 pathway might be a possible novel therapeutic approach for left varicocele-induced epididymal damage.

Unstressing the Reticulum: Nutritional Strategies for Modulating Endoplasmic Reticulum Stress in Obesity

The progression of obesity involves several molecular mechanisms that are closely associated with the pathophysiological response of the disease. Endoplasmic reticulum (ER) stress is one such factor. Lipotoxicity disrupts endoplasmic reticulum homeostasis in the context of obesity. Furthermore, it induces ER stress by activating several signaling pathways via inflammatory responses and oxidative stress. ER performs crucial functions in protein synthesis and lipid metabolism; thus, triggers such as lipotoxicity can promote the accumulation of misfolded proteins in the organelle. The accumulation of these proteins can lead to metabolic disorders and chronic inflammation, resulting in cell death. Thus, alternatives, such as flavonoids, amino acids, and polyphenols that are associated with antioxidant and anti-inflammatory responses have been proposed to attenuate this response by modulating ER stress via the administration of nutrients and bioactive compounds. Decreasing inflammation and oxidative stress can reduce the expression of several ER stress markers and improve clinical outcomes through the management of obesity, including the control of body weight, visceral fat, and lipid accumulation. This review explores the metabolic changes resulting from ER stress and discusses the role of nutritional interventions in modulating the ER stress pathway in obesity.

DAMP sensing and sterile inflammation: intracellular, intercellular and inter-organ pathways

Damage-associated molecular patterns (DAMPs) are endogenous molecules that are released from host cells as a result of cell death or damage. The release of DAMPs in tissues is associated with loss of tissue homeostasis. Sensing of DAMPs by innate immune receptors triggers inflammation, which can be beneficial in initiating the processes that restore tissue homeostasis but can also drive inflammatory diseases. In recent years, the sensing of intracellular DAMPs has received extensive attention in the field of sterile inflammation. However, emerging studies have shown that DAMPs that originate from neighbouring cells, and even from distal tissues or organs, also mediate sterile inflammatory responses. This multi-level sensing of DAMPs is crucial for intercellular, trans-tissue and trans-organ communication. Here, we summarize how DAMP-sensing receptors detect DAMPs from intracellular, intercellular or distal tissue and organ sources to mediate sterile inflammation. We also discuss the possibility of targeting DAMPs or their corresponding receptors to treat inflammatory diseases.

Toll-like receptor 4 damages the intestinal epithelial cells by activating endoplasmic reticulum stress in septic rats

Background

The severity of acute gastrointestinal injury (AGI) is a critical determinant of survival in sepsis. However, there is no specifically interventional management for gastrointestinal dysfunction. Toll-like Receptor 4 (TLR4) is an important contributor to sepsis-induced multiple organ dysfunction syndrome. So, we investigated the effect of TLR4 on leucine-rich repeat-containing G protein-coupled receptor 5 (Lgr5) + cells and goblet cells and its potential mechanism.

Methods

A cecal ligation and puncture (CLP) model reflecting the development of clinical sepsis was developed. Tak-242, a TLR4 inhibitor, was administered to septic rats at a dose of 3 mg/kg via intraperitoneal injection. Immunohistochemistry was performed to detect TLR4 and Lgr5+ cells. AB-PAS staining was performed to detect goblet cells. MUC1 and MUC2 secreted by goblet cells, biomarkers of endoplasmic reticulum (ER) stress and inflammatory cytokines in the intestine were detected by western blotting and real-time PCR.

Results

We found that the upregulation of the TLR4/NF-κB signaling pathway activated intestinal inflammatory response in sepsis. Meanwhile, the structure of intestinal mucosa was destroyed, Lgr5+ cells and goblet cells count were significantly reduced, and the secretory function of goblet cells also decreased. Further studies have found that TLR4 increased the levels of activating transcription factor-6 (ATF6), XBP1, ER chaperone (Bip) and CHOP, but did not activate the protein kinase RNA (PKR)-like ER kinase (P-PERK).

Conclusion

We concluded that the inhibition of TLR4/NF-κB signaling pathway can reduce intestinal inflammatory response, protect intestinal mucosa, protect Lgr5+ cells, goblet cells and relieve ER stress. Our findings suggest that Tak-242 protects Lgr5+ cells and goblet cells after sepsis, partly may be through the suppression of ER stress. Thus, inhibition of TLR4-mediated ER stress may be a promising therapy of septic AGI.

The Prognostic Biomarker RAB7A Promotes Growth and Metastasis of Liver Cancer Cells by Regulating Glycolysis and YAP1 Activation

Activating transcription factor 6 (ATF6) and its downstream genes are involved in progression of hepatocellular carcinoma (HCC). Herein, we demonstrated that sulfhydration of Ras-related protein Rab-7a (RAB7A) was regulated by ATF6. High expression of RAB7A indicated poor prognosis of HCC patients. RAB7A overexpression contributed to proliferation, colony formation, migration, and invasion of HepG2 and Hep3B cells. Furthermore, we found that RAB7A enhanced aerobic glycolysis in HepG2 cells, indicating a higher degree of tumor malignancy. Mechanistically, RAB7A suppressed Yes-associated protein 1 (YAP1) binding to 14-3-3 and conduced to YAP1 nuclear translocation and activation, promoting its downstream gene expression, thereby promoting growth and metastasis of liver cancer cells. In addition, knocking down RAB7A attenuated the progression of orthotopic liver tumors in mice. These findings illustrate the important role of RAB7A in regulating HCC progression. Thus, RAB7A may be a potential innovative target for HCC treatment.

The diverse roles of sphingolipids in inflammatory bowel disease

The incidence of inflammatory bowel disease (IBD) has increased over the last 20 years. A variety of causes, both physiological and environmental, contribute to the initiation and progression of IBD, making disease management challenging. Current treatment options target various aspects of the immune response to dampen intestinal inflammation; however, their effectiveness at retaining remission, their side effects, and loss of response from patients over time warrant further investigation. Finding a common thread within the multitude causes of IBD is critical in developing robust treatment options. Sphingolipids are evolutionary conserved bioactive lipids universally generated in all cell types. This diverse lipid family is involved in a variety of fundamental, yet sometimes opposing, processes such as proliferation and apoptosis. Implicated as regulators in intestinal diseases, sphingolipids are a potential cornerstone in understanding IBD. Herein we will describe the role of host- and microbial-derived sphingolipids as they relate to the many factors of intestinal health and IBD.

Identification of activating transcription factor 6 (ATF6) as a novel prognostic biomarker and potential target in oral squamous cell carcinoma

BACKGROUND

Oral squamous cell carcinoma (OSCC) is originating from oral mucosal epithelial cells. Autophagy plays a crucial role in cancer treatment by promoting cellular self-degradation and eliminating damaged components, thereby enhancing therapeutic efficacy. In this study, we aim to identify a novel autophagy-related biomarker to improve OSCC therapy.

METHODS

We firstly utilized Cox and Lasso analyses to identify that ATF6 is associated with OSCC prognosis, and validated the results by Kaplan-Meier survival analysis. We further identified the downstream pathways and related genes by enrichment analysis and WGCNA analysis. Subsequently, we used short interfering RNA to investigate the effects of ATF6 knockdown on proliferation, migration, apoptosis, and autophagy in SCC-9 and SCC-15 cells through cell viability assay, transwell assay, EdU incorporation assay, flow cytometry analysis, western blot analysis and immunofluorescence analysis, etc. RESULTS: Bioinformatics analyses showed that ATF6 overexpression was associated with prognosis and detrimental to survival. In vitro studies verified that ATF6 knockdown reduced OSCC cell proliferation and migration. Mechanistically, ATF6 knockdown could promote cellular autophagy and apoptosis.

CONCLUSION

We propose that ATF6 holds potential as a prognostic biomarker linked to autophagy in OSCC. This study provides valuable clues for further exploration of targeted therapy against OSCC.

LC3A-mediated autophagy elicits PERK-eIF2α-ATF4 axis activation and mitochondrial dysfunction: Exposing vulnerability in aggresome-positive cancer cells

The unfolded protein response pathways (UPR), autophagy, and compartmentalization of misfolded proteins into inclusion bodies are critical components of the protein quality control network. Among inclusion bodies, aggresomes are particularly intriguing due to their association with cellular survival, drug resistance, and aggresive cancer behavior. Aggresomes are molecular condensates formed when collapsed vimentin cages encircle misfolded proteins before final removal by autophagy. Yet significant gaps persist in the mechanisms governing aggresome formation and elimination in cancer cells. Understanding these mechanisms is crucial, especially considering the involvement of LC3A, a member of the MAP1LC3 family, which plays a unique role in autophagy regulation and has been reported to be epigenetically silenced in many cancers. Herein, we utilized the tetracycline-inducible expression of LC3A to investigate its role in choroid plexus carcinoma cells, which inherently exhibit the presence of aggresomes. Live cell imaging was employed to demonstrate the effect of LC3A expression on aggresome-positive cells, while SILAC-based proteomics identified LC3A-induced protein and pathway alterations. Our findings demonstrated that extended expression of LC3A is associated with cellular senescence. However, the obstruction of lysosomal degradation in this context has a deleterious effect on cellular viability. In response to LC3A-induced autophagy, we observed significant alterations in mitochondrial morphology, reflected by mitochondrial dysfunction and increased ROS production. Furthermore, LC3A expression elicited the activation of the PERK-eIF2α-ATF4 axis of the UPR, underscoring a significant change in the protein quality control network. In conclusion, our results elucidate that LC3A-mediated autophagy alters the protein quality control network, exposing a vulnerability in aggresome-positive cancer cells.

Mogroside V reduced the excessive endoplasmic reticulum stress and mitigated the Ulcerative colitis induced by dextran sulfate sodium in mice

Ulcerative colitis (UC) is an idiopathic, chronic inflammatory condition of the colon, characterized by repeated attacks, a lack of effective treatment options, and significant physical and mental health complications for patients. The endoplasmic reticulum (ER) is a vital intracellular organelle in maintaining cellular homeostasis. Endoplasmic reticulum stress (ERS) is induced when the body is exposed to adverse external stimuli. Numerous studies have shown that ERS-induced apoptosis plays a vital role in the pathogenesis of UC. Mogroside V (MV), an active ingredient of Monk fruit, has demonstrated excellent anti-inflammatory and antioxidant effects. In this study, we investigated the therapeutic effects of MV on dextran sulfate sodium (DSS)-induced UC and its potential mechanisms based on ERS. The results showed that MV exerted a protective effect against DSS-induced UC in mice as reflected by reduced DAI scores, increased colon length, reduced histological scores of the colon, and levels of pro-inflammatory cytokines, as well as decreased intestinal permeability. In addition, the expression of ERS pathway including BIP, PERK, eIF2α, ATF4, CHOP, as well as the apoptosis-related protein including Caspase-12, Bcl-2 and Bax, was found to be elevated in UC. However, MV treatment significantly inhibited the UC and reversed the expression of inflammation signaling pathway including ERS and ERS-induced apoptosis. Additionally, the addition of tunicamycin (Tm), an ERS activator, significantly weakened the therapeutic effect of MV on UC in mice. These findings suggest that MV may be a therapeutic agent for the treatment of DSS-induced UC by inhibiting the activation of the ERS-apoptosis pathway, and may provide a novel avenue for the treatment of UC.

The IRE1α/XBP1 pathway sustains cytokine responses of group 3 innate lymphoid cells in inflammatory bowel disease

Group 3 innate lymphoid cells (ILC3s) are key players in intestinal homeostasis. ER stress is linked to inflammatory bowel disease (IBD). Here, we used cell culture, mouse models, and human specimens to determine whether ER stress in ILC3s affects IBD pathophysiology. We show that mouse intestinal ILC3s exhibited a 24-hour rhythmic expression pattern of the master ER stress response regulator inositol-requiring kinase 1α/X-box-binding protein 1 (IRE1α/XBP1). Proinflammatory cytokine IL-23 selectively stimulated IRE1α/XBP1 in mouse ILC3s through mitochondrial ROS (mtROS). IRE1α/XBP1 was activated in ILC3s from mice exposed to experimental colitis and in inflamed human IBD specimens. Mice with Ire1α deletion in ILC3s (Ire1αΔRorc) showed reduced expression of the ER stress response and cytokine genes including Il22 in ILC3s and were highly vulnerable to infections and colitis. Administration of IL-22 counteracted their colitis susceptibility. In human ILC3s, IRE1 inhibitors suppressed cytokine production, which was upregulated by an IRE1 activator. Moreover, the frequencies of intestinal XBP1s+ ILC3s in patients with Crohn's disease before administration of ustekinumab, an anti-IL-12/IL-23 antibody, positively correlated with the response to treatment. We demonstrate that a noncanonical mtROS-IRE1α/XBP1 pathway augmented cytokine production by ILC3s and identify XBP1s+ ILC3s as a potential biomarker for predicting the response to anti-IL-23 therapies in IBD.

Lipid droplets provide metabolic flexibility for cancer progression

A hallmark of cancer cells is their remarkable ability to efficiently adapt to favorable and hostile environments. Due to a unique metabolic flexibility, tumor cells can grow even in the absence of extracellular nutrients or in stressful scenarios. To achieve this, cancer cells need large amounts of lipids to build membranes, synthesize lipid-derived molecules, and generate metabolic energy in the absence of other nutrients. Tumor cells potentiate strategies to obtain lipids from other cells, metabolic pathways to synthesize new lipids, and mechanisms for efficient storage, mobilization, and utilization of these lipids. Lipid droplets (LDs) are the organelles that collect and supply lipids in eukaryotes and it is increasingly recognized that the accumulation of LDs is a new hallmark of cancer cells. Furthermore, an active role of LD proteins in processes underlying tumorigenesis has been proposed. Here, by focusing on three major classes of LD-resident proteins (perilipins, lipases, and acyl-CoA synthetases), we provide an overview of the contribution of LDs to cancer progression and discuss the role of LD proteins during the proliferation, invasion, metastasis, apoptosis, and stemness of cancer cells.

Naturally occurring small molecules with dual effect upon inflammatory signaling pathways and endoplasmic reticulum stress response

The endoplasmic reticulum (ER) is determinant to maintain cellular proteostasis. Upon unresolved ER stress, this organelle activates the unfolded protein response (UPR). Sustained UPR activates is known to occur in inflammatory processes, deeming the ER a potential molecular target for the treatment of inflammation. This work characterizes the inflammatory/UPR-related molecular machinery modulated by an in-house library of natural products, aiming to pave the way for the development of new selective drugs that act upon the ER to counter inflammation-related chronic diseases. Starting from a library of 134 compounds of natural occurrence, mostly occurring in medicinal plants, nontoxic molecules were screened for their inhibitory capacity against LPS-induced nuclear factor kappa B (NF-κB) activation in a luciferase-based reporter gene assay. Since several natural products inhibited NF-κB expression in THP-1 macrophages, their effect on reactive oxygen species (ROS) production and inflammasome activation was assessed, as well as their transcriptional outcome regarding ER stress. The bioactivities of several natural products are described herein for the first time. We report the anti-inflammatory potential of guaiazulene and describe 5-deoxykaempferol as a novel inhibitor of inflammasome activation. Furthermore, we describe the dual potential of 5-deoxykaempferol, berberine, guaiazulene, luteolin-4'-O-glucoside, myricetin, quercetagetin and sennoside B to modulate inflammatory signaling ER stress. Our results show that natural products are promising molecules for the discovery and pharmaceutical development of chemical entities able to modulate the inflammatory response, as well as proteostasis and the UPR.

Activating transcription factor 6 alleviates secondary brain injury by increasing cystathionine γ-lyase expression in a rat model of intracerebral hemorrhage

BACKGROUND

Intracerebral hemorrhage (ICH) comprises primary and secondary injuries, the latter of which induces increased inflammation and apoptosis and is more severe. Activating transcription factor 6 (ATF6) is a type-II transmembrane protein in the endoplasmic reticulum (ER). ATF6 target genes could improve ER homeostasis, which contributes to cryoprotection. Hence, we predict that ATF6 will have a protective effect on brain tissue after ICH.

METHOD

The ICH rat model was generated through autologous blood injection into the right basal ganglia, the expression of ATF6 after ICH was determined by WB and IF. The expression of ATF6 was effectively controlled by means of intervention, and a series of measures was used to detect cell death, neuroinflammation, brain edema, blood-brain barrier and other indicators after ICH. Finally, the effects on long-term neural function of rats were measured by behavioral means.

RESULT

ATF6 was significantly increased in the ICH-induced brain tissues. Further, ATF6 was found to modulate the expression of cystathionine γ-lyase (CTH) after ICH. Upregulation of ATF6 attenuated neuronal apoptosis and inflammation in ICH rats, along with mitigation of ICH-induced brain edema, blood-brain barrier deterioration, and cognitive behavior defects. Conversely, ATF6 genetic knockdown induced effects counter to those aforementioned.

CONCLUSIONS

This study thereby emphasizes the crucial role of ATF6 in secondary brain injury in response to ICH, indicating that ATF6 upregulation may potentially ameliorate ICH-induced secondary brain injury. Consequently, ATF6 could serve as a promising therapeutic target to alleviate clinical ICH-induced secondary brain injuries.

Preliminary data on cytotoxicity and functional group assessment of a herb-mineral combination against colorectal carcinoma cell line

OBJECTIVES

The invasive screening methods and the late stage diagnosis of colorectal carcinoma (CRC) are contributing for the devastative prognosis. The gradual shift of the disease pattern among younger generations requires the implementation of phytochemicals and traditional medicines. Arkeshwara rasa (AR) is a herb-mineral combination of Tamra bhasma/incinerated copper ashes and Dwigun Kajjali/mercury sulphide levigated with Calotropis procera leaf juice, Plumbago zeylanica root decoction and the decoction of three myrobalans (Terminalia chebula, Terminalia bellerica, Emblica Officinalis decoction)/Triphala decoction.

METHODS

The SW-480 cell line was checked for the cytotoxicity and the cell viability criteria with MTT(3-(4,5-dimethylthiazol-2-yl)-2,5-diphenyl-2H-tetrazolium bromide) assay. The acridine orange/ethidium bromide (AO/EtBr) assay revealed the depth of apoptosis affected cells in the fluorescent images. The FTIR analysis exhibited the graphical spectrum of functional groups within the compound AR.

RESULTS

The IC50 from the 10-7 to 10-3 concentrations against SW-480 cells was 40.4 μg/mL. The staining of AO/EtBr was performed to visualize live and dead cells and it is evident from the result that number of apoptotic cells increases at increasing concentration of AR. The single bond with stretch vibrations of O-H and N-H are more concentrated in the 2,500-3,200 cm-1 and 3,700-4,000 cm-1 of the spectra whereas, the finger print region carries the O-H and S=O type peaks.

CONCLUSIONS

The AR shows strong cyto-toxicity against the SW-480 cells by inducing apoptosis. It also modulates cellular metabolism with the involvement of functional groups which antagonizes the strong acids. Moreover, these effects need to be analyzed further based in the in vivo and various in vitro models.

Aging and atrial fibrillation: A vicious circle

Atrial fibrillation (AF) is the commonest sustained cardiac arrhythmia observed in clinical practice. Its prevalence increases dramatically with advancing age. This review article discusses the recent advances in studies investigating the relationship between aging and AF and the possible underlying mechanisms.

Induction mechanisms of autophagy and endoplasmic reticulum stress in intestinal ischemia-reperfusion injury, inflammatory bowel disease, and colorectal cancer

In recent years, the incidence of intestinal ischemia-reperfusion injury (II/RI), inflammatory bowel disease (IBD), and colorectal cancer (CRC) has been gradually increasing, posing significant threats to human health. Autophagy and endoplasmic reticulum stress (ERS) play important roles in II/RI. Damage caused by ischemia and cellular stress can activate ERS, which in turn initiates autophagy to clear damaged organelles and abnormal proteins, thereby alleviating ERS and maintaining the intestinal environment. In IBD, chronic inflammation damages intestinal tissues and activates autophagy and ERS. Autophagy is initiated by upregulating ATG genes and downregulating factors that inhibit autophagy, thereby clearing abnormal proteins, damaged organelles, and bacteria. Simultaneously, persistent inflammatory stimulation can also trigger ERS, leading to protein imbalance and abnormal folding in the ER lumen. The activation of ERS can maintain cellular homeostasis by initiating the autophagy process, thereby reducing inflammatory responses and cell apoptosis in the intestine. In CRC, excessive cell proliferation and protein synthesis lead to increased ERS. The activation of ERS, regulated by signaling pathways such as IRE1α and PERK, can initiate autophagy to clear abnormal proteins and damaged organelles, thereby reducing the negative effects of ERS. It can be seen that autophagy and ERS play a crucial regulatory role in the development of intestinal diseases. Therefore, the progress in targeted therapy for intestinal diseases based on autophagy and ERS provides novel strategies for managing intestinal diseases. In this paper, we review the advances in regulation of autophagy and ERS in intestinal diseases, emphasizing the potential molecular mechanisms for therapeutic applications.

Immunologic Crosstalk of Endoplasmic Reticulum Stress Signaling in Bladder Cancer

Bladder cancer (BC) is a common malignant tumor of the urinary system. While current approaches involving adjuvant chemotherapy, radiotherapy, and immunotherapy have shown significant progress in BC treatment, challenges, such as recurrence and drug resistance, persist, especially in the case of muscle-invasive bladder cancer (MIBC). It is mainly due to the lack of pre-existing immune response cells in the tumor immune microenvironment. Micro-environmental changes (such as hypoxia and under-nutrition) can cause the aggregation of unfolded and misfolded proteins in the lumen, which induces endoplasmic reticulum (ER) stress. ER stress and its downstream signaling pathways are closely related to immunogenicity and tumor drug resistance. ER stress plays a pivotal role in a spectrum of processes within immune cells and the progression of BC cells, encompassing cell proliferation, autophagy, apoptosis, and resistance to therapies. Recent studies have increasingly recognized the potential of natural compounds to exhibit anti-BC properties through ER stress induction. Still, the efficacy of these natural compounds remains less than that of immune checkpoint inhibitors (ICIs). Currently, the ER stress-mediated immunogenic cell death (ICD) pathway is more encouraging, which can enhance ICI responses by mediating immune stemness. This article provides an overview of the recent developments in understanding how ER stress influences tumor immunity and its implications for BC. Targeting this pathway may soon emerge as a compelling therapeutic strategy for BC.

An EMC-Hpo-Yki axis maintains intestinal homeostasis under physiological and pathological conditions

Balanced control of stem cell proliferation and differentiation underlines tissue homeostasis. Disruption of tissue homeostasis often results in many diseases. However, how endogenous factors influence the proliferation and differentiation of intestinal stem cells (ISCs) under physiological and pathological conditions remains poorly understood. Here, we find that the evolutionarily conserved endoplasmic reticulum membrane protein complex (EMC) negatively regulates ISC proliferation and intestinal homeostasis. Compromising EMC function in progenitors leads to excessive ISC proliferation and intestinal homeostasis disruption. Mechanistically, the EMC associates with and stabilizes Hippo (Hpo) protein, the key component of the Hpo signaling pathway. In the absence of EMC, Yorkie (Yki) is activated to promote ISC proliferation due to Hpo destruction. The EMC-Hpo-Yki axis also functions in enterocytes to maintain intestinal homeostasis. Importantly, the levels of the EMC are dramatically diminished in tunicamycin-treated animals, leading to Hpo destruction, thereby resulting in intestinal homeostasis disruption due to Yki activation. Thus, our study uncovers the molecular mechanism underlying the action of the EMC in intestinal homeostasis maintenance under physiological and pathological conditions and provides new insight into the pathogenesis of tunicamycin-induced tumorigenesis.

Endoplasmic Reticulum Stress and Its Impact on Adipogenesis: Molecular Mechanisms Implicated

Endoplasmic reticulum (ER) stress plays a pivotal role in adipogenesis, which encompasses the differentiation of adipocytes and lipid accumulation. Sustained ER stress has the potential to disrupt the signaling of the unfolded protein response (UPR), thereby influencing adipogenesis. This comprehensive review illuminates the molecular mechanisms that underpin the interplay between ER stress and adipogenesis. We delve into the dysregulation of UPR pathways, namely, IRE1-XBP1, PERK and ATF6 in relation to adipocyte differentiation, lipid metabolism, and tissue inflammation. Moreover, we scrutinize how ER stress impacts key adipogenic transcription factors such as proliferator-activated receptor γ (PPARγ) and CCAAT-enhancer-binding proteins (C/EBPs) along with their interaction with other signaling pathways. The cellular ramifications include alterations in lipid metabolism, dysregulation of adipokines, and aged adipose tissue inflammation. We also discuss the potential roles the molecular chaperones cyclophilin A and cyclophilin B play in adipogenesis. By shedding light on the intricate relationship between ER stress and adipogenesis, this review paves the way for devising innovative therapeutic interventions.

New insights into the unfolded protein response (UPR)-anterior gradient 2 (AGR2) pathway in the regulation of intestinal barrier function in weaned piglets

Sustained dysfunction of the intestinal barrier caused by early weaning is a major factor that induces postweaning diarrhea in weaned piglets. In both healthy and diseased states, the intestinal barrier is regulated by goblet cells. Alterations in the characteristics of goblet cells are linked to intestinal barrier dysfunction and inflammatory conditions during pathogenic infections. In this review, we summarize the current understanding of the mechanisms of the unfolded protein response (UPR) and anterior gradient 2 (AGR2) in maintaining intestinal barrier function and how modifications to these systems affect mucus barrier characteristics and goblet cell dysregulation. We highlight a novel mechanism underlying the UPR-AGR2 pathway, which affects goblet cell differentiation and maturation and the synthesis and secretion of mucin by regulating epidermal growth factor receptor and mucin 2. This study provides a theoretical basis and new insights into the regulation of intestinal health in weaned piglets.

The PERK Branch of the Unfolded Protein Response Safeguards Protein Homeostasis and Mesendoderm Specification of Human Pluripotent Stem Cells

Cardiac development involves large-scale rearrangements of the proteome. How the developing cardiac cells maintain the integrity of the proteome during the rapid lineage transition remains unclear. Here it is shown that proteotoxic stress visualized by the misfolded and/or aggregated proteins appears during early cardiac differentiation of human pluripotent stem cells and is resolved by activation of the PERK branch of unfolded protein response (UPR). PERK depletion increases misfolded and/or aggregated protein accumulation, leading to pluripotency exit defect and impaired mesendoderm specification of human pluripotent stem cells. Mechanistically, it is found that PERK safeguards mesendoderm specification through its conserved downstream effector ATF4, which subsequently activates a novel transcriptional target WARS1, to cope with the differentiation-induced proteotoxic stress. The results indicate that protein quality control represents a previously unrecognized core component of the cardiogenic regulatory network. Broadly, these findings provide a framework for understanding how UPR is integrated into the developmental program by activating the PERK-ATF4-WARS1 axis.

HIV-1 replication requires optimal activation of the unfolded protein response

Several human diseases including viral infections activate the unfolded protein response (UPR) due to abnormal accumulation of unfolded/misfolded proteins. However, UPR modulation and its functional relevance in HIV-1 infection lack comprehensive elucidation. This study reveals that HIV-1 activates IRE1, PERK, and ATF6 signaling pathways of UPR. The knockdown of PERK and ATF6 reduces HIV-1 long terminal repeat (LTR)-driven gene expression, whereas the endoplasmic reticulum (ER) chaperone HSPA5 prevents proteasomal degradation of HIV-1 p24 through its chaperone activity. Interestingly, overstimulation of UPR by a chemical inducer leads to anti-HIV activity through an enhanced type-1 interferon response. Also, treatment with a chemical ER stress inhibitor reduces HIV-1 replication. These findings suggest that an optimal UPR activation is crucial for effective viral replication, as either overstimulating UPR or inhibiting ER stress leads to viral suppression.

Silicon dioxide-induced endoplasmic reticulum stress of alveolar macrophages and its role on the formation of silicosis fibrosis: a review article

Silicosis is a chronic lung inflammatory disease induced by long-term inhalation of high concentrations of silicon dioxide (SiO2), characterized by pulmonary fibrosis. Inhalation of silica invades alveolar macrophages (AMs) and changes the micro-environment of the cell, resulting in abnormal morphology and dysfunction of the endoplasmic reticulum (ER). Once beyond the range of cell regulation, the endoplasmic reticulum stress (ERS) will occur, which will lead to cell damage, necrosis, and apoptosis, eventually causing silicosis fibrosis through various mechanisms. This is a complex and delicate process accompanied by various macrophage-derived cytokines. Unfortunately, the details have not been systematically summarized yet. In this review, we systematically introduce the basic two processes: the process of inducing ERS by inhaling SiO2 and the process of inducing pulmonary fibrosis by ERS. Moreover, the underlying mechanism of the above two sequential events is also be discussed. We conclude that the ERS of alveolar macrophages caused by silica dust are involved deeply in the pathogenesis of silicosis. Therefore, changing the states of SiO2-induced ERS of macrophage may be an attractive therapeutic target for silicosis fibrosis.

Activating transcription factor (ATF) 6 upregulates cystathionine β synthetase (CBS) expression and hydrogen sulfide (H2S) synthesis to ameliorate liver metabolic damage

Activating transcription factor 6 (ATF6) is an endoplasmic reticulum stress responsive gene. We previously reported that conditional knockout of hepatic ATF6 exacerbated liver metabolic damage by repressing autophagy through mTOR pathway. However, the mechanism by which ATF6 influence liver metabolism has not been well established. Hydrogen sulfide (H2S) is a gaseous signaling molecule that plays an important role in regulating inflammation, and suppress nonalcoholic fatty liver in mice. Based on the previous study, we assumed that ATF6 may regulate H2S production to participate in liver metabolism. In order to clarify the mechanism by which ATF6 regulates H2S synthesis to ameliorate liver steatosis and inflammatory environment, we conducted the present study. We used the liver specific ATF6 knockout mice and fed on high-fat-diet, and found that H2S level was significantly downregulated in hepatic ATF6 knockout mice. Restoring H2S by the administration of slow H2S releasing agent GYY4137 ameliorated the hepatic steatosis and glucose tolerance. ATF6 directly binds to the promoter of cystathionine β synthetase (CBS), an important enzyme in H2S synthesis. Thus, ATF6 could upregulate H2S production through CBS. Sulfhydrated Sirtuin-1 (SIRT1) was downregulated in ATF6 knockout mice. The expression of pro-inflammatory factor IL-17A was upregulated and anti-inflammatory factor IL-10 was downregulated in ATF6 knockout mice. Our results suggest that ATF6 can transcriptionally enhance CBS expression as well as H2S synthesis. ATF6 increases SIRT1 sulfhydration and ameliorates lipogenesis and inflammation in the fatty liver. Therefore, ATF6 could be a novel therapeutic strategy for high-fat diet induced fatty liver metabolic abnormalities.

Downregulation of Heat Shock Protein 72 Contributes to Fibrostenosis in Crohn's Disease

Background/Aims

Crohn's disease (CD) with recurrent inflammation can cause intestinal fibrostenosis due to dysregulated deposition of extracellular matrix. However, little is known about the pathogenesis of fibrostenosis. Here, we performed a differential proteomic analysis between normal, inflamed, and fibrostenotic specimens of patients with CD and investigated the roles of the candidate proteins in myofibroblast activation and fibrosis.

Methods

We performed two-dimensional difference gel electrophoresis and identified candidate proteins using matrix-assisted laser desorption/ionization time-of-flight mass spectrometry and orbitrap liquid chromatography-mass spectrometry. We also verified the levels of candidate proteins in clinical specimens and examined their effects on 18Co myofibroblasts and Caco-2 intestinal epithelial cells.

Results

We identified five of 30 proteins (HSP72, HSPA5, KRT8, PEPCK-M, and FABP6) differentially expressed in fibrostenotic CD. Among these proteins, the knockdown of heat shock protein 72 (HSP72) promoted the activation and wound healing of myofibroblasts. Moreover, knockdown of HSP72 induced the epithelial-mesenchymal transition of intestinal epithelial cells by reducing E-cadherin and inducing fibronectin and α-smooth muscle actin, which contribute to fibrosis.

Conclusions

HSP72 is an important mediator that regulates myofibroblasts and epithelial-mesenchymal transition in fibrosis of CD, suggesting that HSP72 can serve as a target for antifibrotic therapy.

The SYSCID map: a graphical and computational resource of molecular mechanisms across rheumatoid arthritis, systemic lupus erythematosus and inflammatory bowel disease

Chronic inflammatory diseases (CIDs), including inflammatory bowel disease (IBD), rheumatoid arthritis (RA) and systemic lupus erythematosus (SLE) are thought to emerge from an impaired complex network of inter- and intracellular biochemical interactions among several proteins and small chemical compounds under strong influence of genetic and environmental factors. CIDs are characterised by shared and disease-specific processes, which is reflected by partially overlapping genetic risk maps and pathogenic cells (e.g., T cells). Their pathogenesis involves a plethora of intracellular pathways. The translation of the research findings on CIDs molecular mechanisms into effective treatments is challenging and may explain the low remission rates despite modern targeted therapies. Modelling CID-related causal interactions as networks allows us to tackle the complexity at a systems level and improve our understanding of the interplay of key pathways. Here we report the construction, description, and initial applications of the SYSCID map (https://syscid.elixir-luxembourg.org/), a mechanistic causal interaction network covering the molecular crosstalk between IBD, RA and SLE. We demonstrate that the map serves as an interactive, graphical review of IBD, RA and SLE molecular mechanisms, and helps to understand the complexity of omics data. Examples of such application are illustrated using transcriptome data from time-series gene expression profiles following anti-TNF treatment and data from genome-wide associations studies that enable us to suggest potential effects to altered pathways and propose possible mechanistic biomarkers of treatment response.

Insights into the intestinal toxicity of foodborne mycotoxins through gut microbiota: A comprehensive review

Mycotoxins, which are fungal metabolites, pose a significant global food safety concern by extensively contaminating food and feed, thereby seriously threatening public health and economic development. Many foodborne mycotoxins exhibit potent intestinal toxicity. However, the mechanisms underlying mycotoxin-induced intestinal toxicity are diverse and complex, and effective prevention or treatment methods for this condition have not yet been established in clinical and animal husbandry practices. In recent years, there has been increasing attention to the role of gut microbiota in the occurrence and development of intestinal diseases. Hence, this review aims to provide a comprehensive summary of the intestinal toxicity mechanisms of six common foodborne mycotoxins. It also explores novel toxicity mechanisms through the "key gut microbiota-key metabolites-key targets" axis, utilizing multiomics and precision toxicology studies with a specific focus on gut microbiota. Additionally, we examine the potential beneficial effects of probiotic supplementation on mycotoxin-induced toxicity based on initial gut microbiota-mediated mycotoxicity. This review offers a systematic description of how mycotoxins impact gut microbiota, metabolites, and genes or proteins, providing valuable insights for subsequent toxicity studies of mycotoxins. Furthermore, it lays a theoretical foundation for preventing and treating intestinal toxicity caused by mycotoxins and advancing food safety practices.

The effect of mindfulness interventions on stress in medical students: A systematic review and meta-analysis

BACKGROUND

Medical students have high levels of stress, which is associated with higher incidents of burnout, depression, and suicide compared to age-matched peers. Mindfulness practices have been shown to reduce stress among medical students.

PURPOSE

The purpose of this systematic review and meta-analysis was to examine if mindfulness interventions have an overall effect on stress outcomes in the high-stress population of medical students globally, particularly given the wide variety of interventions. Any intervention designed to promote mindfulness was included.

METHODS

A comprehensive literature search was completed to include multiple databases, ancestry, and hand-searching and 35 studies were included. Standardized mean difference effect sizes (ES) were synthesized across studies using a random-effects model for changes in stress levels in medical students ≥ 18. Moderator analyses were performed to explore variations in effects by participant and intervention characteristics.

RESULTS

Mindfulness interventions significantly improved stress among medical students in both the two-arm studies (d = 0.370, k = 19, n = 2,199, 95% CI 0.239-0.501, p < .001) and one-arm pre-post studies (d = 0.291, k = 30, n = 18 (two cohorts from Dyrbye et al), 95% CI 0.127-0.455, p = 0.001). Moderator analyses found trends in less hours and less required practice resulted in better improvement in stress.

CONCLUSIONS

This study further confirms that despite a wide variety of mindfulness interventions for medical students around the world, they produce an overall small-to-moderate effect on stress reduction. Future research looking at the most effective protocols for high-stress medical students would be beneficial.

Corneal neuroepithelial compartmentalized microfluidic chip model for evaluation of toxicity-induced dry eye

Part of the lacrimal functional unit, the cornea protects the ocular surface from numerous environmental aggressions and xenobiotics. Toxicological evaluation of compounds remains a challenge due to complex interactions between corneal nerve endings and epithelial cells. To this day, models do not integrate the physiological specificity of corneal nerve endings and are insufficient for the detection of low toxic effects essential to anticipate Toxicity-Induced Dry Eye (TIDE). Using high-content imaging tool, we here characterize toxicity-induced cellular alterations using primary cultures of mouse trigeminal sensory neurons and corneal epithelial cells in a compartmentalized microfluidic chip. We validate this model through the analysis of benzalkonium chloride (BAC) toxicity, a well-known preservative in eyedrops, after a single (6h) or repeated (twice a day for 15 min over 5 days) topical 5.10-4% BAC applications on the corneal epithelial cells and nerve terminals. In combination with high-content image analysis, this advanced microfluidic protocol reveal specific and tiny changes in the epithelial cells and axonal network as well as in trigeminal cells, not directly exposed to BAC, with ATF3/6 stress markers and phospho-p44/42 cell activation marker. Altogether, this corneal neuroepithelial chip enables the evaluation of toxic effects of ocular xenobiotics, distinguishing the impact on corneal sensory innervation and epithelial cells. The combination of compartmentalized co-culture/high-content imaging/multiparameter analysis opens the way for the systematic analysis of toxicants but also neuroprotective compounds.

Autophagy in intestinal epithelial cells prevents gut inflammation

Intestinal epithelial cells form the largest barrier in the body, separating us from the outside world. Here, we review recent findings that highlight the role of autophagy in the cell-intrinsic response of the epithelial cells to the harsh intestinal environment and how they shape host physiology.

3-Acetyldeoxynivalenol induces apoptosis, barrier dysfunction and endoplasmic reticulum stress by inhibiting mTORC1-dependent autophagy in porcine enterocytes

3-Acetyldeoxynivalenol (3-Ac-DON), an acetylated form of deoxynivalenol, is widely present in mycotoxin-contaminated food, feed as well as in other natural sources. Ingestion of 3-Ac-DON may result in intestinal dysfunction, leading to gut diseases in humans and animals. Nevertheless, the molecular mechanism of 3-Ac-DON in intestinal epithelial cytotoxicity remains unclear. In this study, intestinal porcine epithelial cell line 1 (IPEC-1) cells were treated with different concentrations of 3-Ac-DON for 12 h or 24 h, respectively. The results showed that 3-Ac-DON caused decreased cell viability, cell cycle arrest in G1 phase and depolarization of mitochondrial membrane potential. Western blotting analysis showed that 3-Ac-DON significantly decreased the expression of tight junction proteins, inhibited autophagy and activated endoplasmic reticulum (ER) stress in IPEC-1 cells (P < 0.05). Further investigation demonstrated that 3-Ac-DON caused apoptosis, ER stress and barrier dysfunction were reversed after co-treatment with the autophagy activator rapamycin (100 nM), indicating that autophagy plays a key role in the process of 3-Ac-DON-induced cell damage. In addition, we demonstrated that 3-Ac-DON inhibits the occurrence of autophagy mediated by mTORC1 protein. In conclusion, our research indicated that the mTORC1 protein and autophagy played a key role in the 3-Ac-DON-induced cytotoxic in IPEC-1 cells, which would provide new therapeutic targets and ideas for 3-Ac-DON-mediated intestinal injury.

Role of SIRT2 in intestinal barrier under cold exposure

Prolonged cold exposure causes body stress and damages health. The intestinal environment is complex and variable, and direct contact with the external environment can easily cause stress, damage and even lead to diseases such as diarrhea.

AIMS

This study aimed to reveal the role of cold exposure on ileum damage and the role of SIRT2 in this process.

MAIN METHODS

C57BL6 mice and SIRT2 knockout mice were used to construct a chronic cold exposure model (21 days, random 4 °C exposure for 3 h per day), which was tested by various methods, including intestinal permeability assays, morphological assays, ultrastructural assays, western blotting, and fluorescence staining. In vitro assays were performed on the mouse small intestinal epithelial cell line MODE-K to investigate the role of endoplasmic reticulum stress, SIRT2 knockout, and autophagy on tight junctions.

KEY FINDINGS

The results showed that chronic cold exposure damaged the ileal epithelial barrier, with endoplasmic reticulum stress. Knockout of SIRT2 alleviates ileal injury via enhanced autophagy under cold exposure. And autophagy can restore the expression of ZO-1 under stress.

SIGNIFICANCE

This study can provide potential target and basic data for the treatment of IBD and other disorders of the intestinal barrier. Autophagy may be an important means of restoring damage to the intestinal barrier.