Endoplasmic Reticulum Stress in Colonic Mucosa of Ulcerative Colitis Patients Is Mediated by PERK and IRE1 Pathway Activation

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.

In Vitro Inhibition of Endoplasmic Reticulum Stress: A Promising Therapeutic Strategy for Patients with Crohn's Disease

BACKGROUND

Crohn's disease (CD) is an inflammatory bowel disease marked by an abnormal immune response and excessive pro-inflammatory cytokines, leading to impaired protein processing and endoplasmic reticulum (ER) stress. This stress, caused by the accumulation of misfolded proteins, triggers the unfolded protein response (UPR) through IRE1/Xbp-1, PERK/eIF2α, and ATF6 pathways, which are linked to intestinal inflammation. This study aimed to investigate ER stress in CD patients' intestinal mucosa and evaluate phenylbutyrate (PBA) as an ER stress inhibitor.

METHODS

Colon biopsies from CD patients and controls were cultured under five conditions, including 4-PBA treatments. Real-time PCR, cytokine level, and immunohistochemistry were performed.

RESULTS

Immunohistochemistry revealed that ER stress was activated in CD patients' intestinal epithelial cells and lamina propria cells. PERK/eIF2α, but not IRE1/Xbp-1 or ATF6, was upregulated in CD patients compared to controls. UPR-related genes (STC2, CALR, HSPA5, HSP90B1) were also elevated in CD patients. PBA treatment significantly reduced ER stress and UPR markers while decreasing apoptotic markers like DDIT3. Pro-inflammatory cytokines, such as IL-1β, IL-6, IL-17, TNF- α, and sCD40L, were significantly reduced after PBA treatment.

CONCLUSION

ER stress and UPR pathways are activated in CD colonic mucosa, and PBA reduces these markers, suggesting potential therapeutic benefits for CD-related inflammation.

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.

Quantitative proteomic studies of the intestinal mucosa provide new insights into the molecular mechanism of ulcerative colitis

BACKGROUND

Differentiation between ulcerative colitis (UC) and other intestinal inflammatory diseases is difficult, and the precise etiology of UC is poorly understood. Thus, there is a need for novel diagnostic and prognostic biomarkers for UC.

METHODS

Intestinal mucosal biopsy tissue specimens of inflamed (ulcerative colitis-inflamed, UC-I) and non-inflamed (ulcerative colitis-noninflamed, UC-N) tissue were obtained simultaneously during colonoscopy from newly diagnosed UC patients prior to any treatments. Label-free liquid chromatography tandem mass spectrometry (LC-MS/MS) quantitative proteomics was used to detect proteomic differences between UC-I, UC-N, and normal control subjects (n = 5). Proteins with a fold-change > 1.5 and P < 0.05 between groups were considered to be differentially expressed (DEPs). Candidate biomarkers were further verified in 8 patients of each group by parallel reaction monitoring (PRM) (a prospective cohort, n = 8). Expression of TXNDC5 was quantified using immunohistochemistry (IHC).

RESULTS

A total of 4,788 proteins were identified. Multiple upregulated pathways, including leukocyte trans-endothelial migration and natural killer (NK) cell-mediated cytotoxicity, were identified. Network analysis showed that proteins were involved in 4 pathways in UC-I and 3 pathways in UC-N tissues, and participated in protein-protein interactions. Increased expression of 9 DEPs, including TXNDC5, EPX, and ITGAM were detected in UC patients compared to normal control subjects. Subsequent verification of the 9 DEPs by PRM confirmed the reliability of the mass spectrometry data. TXNDC5 expression was significantly increased in UC.

CONCLUSIONS

The pathways, networks, and proteins identified in this study may provide new insights into the molecular pathogenesis of UC. Further studies are required to determine if the proteins identified may help in the diagnosis and treatment of UC.

Critical Knowledge Gaps and Future Priorities Regarding the Intestinal Barrier Damage After Traumatic Brain Injury

The analysis aims to provide a comprehensive understanding of the current landscape of research on the Intestinal barrier damage after traumatic brain injury (TBI), elucidate specific mechanisms, and address knowledge gaps to help guide the development of targeted therapeutic interventions and improve outcomes for individuals with TBI. A total of 2756 relevant publications by 13,778 authors affiliated within 3198 institutions in 79 countries were retrieved from the Web of Science. These publications have been indexed by 1139 journals and cited 158, 525 references. The most productive author in this field was Sikiric P, and the University of Pittsburgh was identified as the most influential institution. The United States was found to be the leading country in terms of article output and held a dominant position in this field. The International Journal of Molecular Sciences was identified as a major source of publications in this area. In terms of collaboration, the cooperation between the United States and China was found to be the most extensive among countries, institutions, and authors, indicating a high level of influence in this field. Keyword co-occurrence network analysis revealed several hotspots in this field, including the microbiome-gut-brain axis, endoplasmic reticulum stress, cellular autophagy, ischemia-reperfusion, tight junctions, and intestinal permeability. The analysis of keyword citation bursts suggested that ecological imbalance and gut microbiota may be the forefront of future research. The findings of this study can serve as a reference and guiding perspective for future research in this field.

Autophagy: A potential target for natural products in the treatment of ulcerative colitis

Ulcerative colitis (UC) is a chronic inflammatory bowel disease primarily affecting the mucosa of the colon and rectum. UC is characterized by recurrent episodes, often necessitating lifelong medication use, imposing a significant burden on patients. Current conventional and advanced treatments for UC have the disadvantages of insufficient efficiency, susceptibility to drug resistance, and notable adverse effects. Therefore, developing effective and safe drugs has become an urgent need. Autophagy is an intracellular degradation process that plays an important role in intestinal homeostasis. Emerging evidence suggests that aberrant autophagy is involved in the development of UC, and modulating autophagy can effectively alleviate experimental colitis. A growing number of studies have established that autophagy can interplay with endoplasmic reticulum stress, gut microbiota, apoptosis, and the NLRP3 inflammasome, all of which contribute to the pathogenesis of UC. In addition, a variety of intestinal epithelial cells, including absorptive cells, goblet cells, and Paneth cells, as well as other cell types like neutrophils, antigen-presenting cells, and stem cells in the gut, mediate the development of UC through autophagy. To date, many studies have found that natural products hold the potential to exert therapeutic effects on UC by regulating autophagy. This review focuses on the possible effects and pharmacological mechanisms of natural products to alleviate UC with autophagy as a potential target in recent years, aiming to provide a basis for new drug development.

The down-regulation of STC2 mRNA may serve as a biomarker for death from mechanical asphyxia

Death from mechanical asphyxia (DMA) is a common cause of death in forensic pathology. However, due to the lack of biomarkers, the authentication of DMA now relies on a series of non-specific signs, which may cause troubles in the judicial trials, especially when the criminal scene is not fully elucidated. To search for the potential biomarkers for DMA, brain samples of DMA and craniocerebral injury groups were screened by microarray. The obtained mRNAs were validated by animal and human samples. Primary cell culture was conducted to explore the biochemical changes under hypoxia. 415 differentially expressed mRNAs between two groups were discovered. Ten mRNAs were examined in both human and animal samples died of different causes of death. Stanniocalcin-2 (STC2) showed significant down-regulation in DMA samples compared to other groups, regardless of PMI, age, or temperature. Cellular experiments indicated that ROS level peaked after 15-min-hypoxic culture, when the expression level of STC2 was significant down-regulated simultaneously. The ER-stress-related proteins also showed potential connection with STC2. In general, it is indicated that the down-regulation of STC2 may serve as a biomarker for DMA.

Selection Signal Analysis Reveals Hainan Yellow Cattle Are Being Selectively Bred for Heat Tolerance

Hainan yellow cattle are indigenous Zebu cattle from southern China known for their tolerance of heat and strong resistance to disease. Generations of adaptation to the tropical environment of southern China and decades of artificial breeding have left identifiable selection signals in their genomic makeup. However, information on the selection signatures of Hainan yellow cattle is scarce. Herein, we compared the genomes of Hainan yellow cattle with those of Zebu, Qinchuan, Nanyang, and Yanbian cattle breeds by the composite likelihood ratio method (CLR), Tajima's D method, and identifying runs of homozygosity (ROHs), each of which may provide evidence of the genes responsible for heat tolerance in Hainan yellow cattle. The results showed that 5210, 1972, and 1290 single nucleotide polymorphisms (SNPs) were screened by the CLR method, Tajima's D method, and ROH method, respectively. A total of 453, 450, and 325 genes, respectively, were identified near these SNPs. These genes were significantly enriched in 65 Gene Ontology (GO) functional terms and 11 Kyoto Encyclopedia of Genes and Genomes (KEGG) pathways (corrected p < 0.05). Five genes-Adenosylhomocysteinase-like 2, DnaJ heat shock protein family (Hsp40) member C3, heat shock protein family A (Hsp70) member 1A, CD53 molecule, and zinc finger and BTB domain containing 12-were recognized as candidate genes associated with heat tolerance. After further functional verification of these genes, the research results may benefit the understanding of the genetic mechanism of the heat tolerance in Hainan yellow cattle, which lay the foundation for subsequent studies on heat stress in this breed.

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.

Jianpi-Qingchang decoction alleviates ulcerative colitis by modulating endoplasmic reticulum stress-related autophagy in intestinal epithelial cells

Endoplasmic reticulum stress (ERS)-related autophagy is involved in the occurrence and development of ulcerative colitis (UC). Therefore, regulating ERS-related autophagy is a potential therapeutic target for the treatment of UC. Jianpi-Qingchang (JPQC) decoction, consisting of nine Chinese herbal medicines, is used to treat patients with UC. However, its mechanism of action has not been completely elucidated. Here, we aimed to reveal the therapeutic effects and mechanisms of JPQC in UC. We established a colitis model using dextran sulfate sodium (DSS) and an ERS model using thapsigargin (Tg) and administered JPQC. We systematically examined ERS-related autophagy associated protein expression, inflammatory cytokines, apoptotic cells, and autophagic flux. Moreover, the cellular ultrastructure was observed via transmission electron microscopy (TEM). We found that JPQC reduced disease activity index (DAI) scores, counteracted colonic tissue damage, decreased the number of autophagosomes, inhibited proinflammatory cytokines, enhanced anti-inflammatory cytokines, and dampened ERS-related autophagy associated protein gene expression.

Voglibose Regulates the Secretion of GLP-1 Accompanied by Amelioration of Ileal Inflammatory Damage and Endoplasmic Reticulum Stress in Diabetic KKAy Mice

Voglibose is an α-glycosidase inhibitor that improves postprandial hyperglycemia and increases glucagon-like peptide-1 (GLP-1) secretion in patients with type 2 diabetes. Recently, there has been increasing interest in the anti-inflammatory effects of voglibose on the intestine, but the underlying mechanism is not clear. This study evaluated the effects and mechanisms of voglibose on glycemic control and intestinal inflammation. Type 2 diabetic KKAy mice were treated with voglibose (1 mg/kg) by oral gavage once daily. After 8 weeks, glucose metabolism, levels of short-chain fatty acids (SCFAs), systematic inflammatory factors, intestinal integrity and inflammation were evaluated using hematoxylin and eosin staining, immunohistochemistry, immunofluorescence and Western blot analysis. Voglibose ameliorated glucose metabolism by enhancing basal- and glucose-dependent GLP-1 secretion. Several beneficial SCFAs, such as acetic acid and propionic acid, were increased by voglibose in the fecal sample. Additionally, voglibose notably decreased the proportion of pro-inflammatory macrophages and the expression of nuclear factor kappa B but increased the expression of tight junction proteins in the ileum, thus markedly improving intestinal inflammatory damage and reducing the systematic inflammatory factors. Ileal genomics and protein validation suggested that voglibose attenuated inositol-requiring protein 1α-X-box binding protein 1-mediated endoplasmic reticulum stress (ERS). Together, these results showed that voglibose enhanced the secretion of GLP-1, which contributed to the glycemic control in KKAy mice at least in part by regulating intestinal inflammation and the expression of ERS factors.