Bitter melon protects against ER stress in LS174T colonic epithelial cells

Traditional Chinese Medicine Targeting Heat Shock Proteins as Therapeutic Strategy for Heart Failure

Heart failure (HF) is the terminal stage of multifarious heart diseases and is responsible for high hospitalization rates and mortality. Pathophysiological mechanisms of HF include cardiac hypertrophy, remodeling and fibrosis resulting from cell death, inflammation and oxidative stress. Heat shock proteins (HSPs) can ameliorate folding of proteins, maintain protein structure and stability upon stress, protect the heart from cardiac dysfunction and ameliorate apoptosis. Traditional Chinese medicine (TCM) regulates expression of HSPs and has beneficial therapeutic effect in HF. In this review, we summarized the function of HSPs in HF and the role of TCM in regulating expression of HSPs. Studying the regulation of HSPs by TCM will provide novel ideas for the study of the mechanism and treatment of HF.

An update on extra-oral bitter taste receptors

Bitter taste-sensing type 2 receptors (TAS2Rs or T2Rs), belonging to the subgroup of family A G-protein coupled receptors (GPCRs), are of crucial importance in the perception of bitterness. Although in the first instance, TAS2Rs were considered to be exclusively distributed in the apical microvilli of taste bud cells, numerous studies have detected these sensory receptor proteins in several extra-oral tissues, such as in pancreatic or ovarian tissues, as well as in their corresponding malignancies. Critical points of extra-oral TAS2Rs biology, such as their structure, roles, signaling transduction pathways, extensive mutational polymorphism, and molecular evolution, have been currently broadly studied. The TAS2R cascade, for instance, has been recently considered to be a pivotal modulator of a number of (patho)physiological processes, including adipogenesis or carcinogenesis. The latest advances in taste receptor biology further raise the possibility of utilizing TAS2Rs as a therapeutic target or as an informative index to predict treatment responses in various disorders. Thus, the focus of this review is to provide an update on the expression and molecular basis of TAS2Rs functions in distinct extra-oral tissues in health and disease. We shall also discuss the therapeutic potential of novel TAS2Rs targets, which are appealing due to their ligand selectivity, expression pattern, or pharmacological profiles.

Short-Chain Naphthoquinone Protects Against Both Acute and Spontaneous Chronic Murine Colitis by Alleviating Inflammatory Responses

Ulcerative colitis (UC) is characterised by chronic, relapsing, idiopathic, and multifactorial colon inflammation. Recent evidence suggests that mitochondrial dysfunction plays a critical role in the onset and recurrence of this disease. Previous reports highlighted the potential of short-chain quinones (SCQs) for the treatment of mitochondrial dysfunction due to their reversible redox characteristics. We hypothesised that a recently described potent mitoprotective SCQ (UTA77) could ameliorate UC symptoms and pathology. In a dextran sodium sulphate- (DSS-) induced acute colitis model in C57BL/6J mice, UTA77 substantially improved DSS-induced body weight loss, disease activity index (DAI), colon length, and histopathology. UTA77 administration also significantly increased the expression of tight junction (TJ) proteins occludin and zona-occludin 1 (ZO-1), which preserved intestinal barrier integrity. Similar responses were observed in the spontaneous Winnie model of chronic colitis, where UTA77 significantly improved DAI, colon length, and histopathology. Furthermore, UTA77 potently suppressed elevated levels of proinflammatory cytokines and chemokines in colonic explants of both DSS-treated and Winnie mice. These results strongly suggest that UTA77 or its derivatives could be a promising novel therapeutic approach for the treatment of human UC.

Potential therapeutic compounds from traditional Chinese medicine targeting endoplasmic reticulum stress to alleviate rheumatoid arthritis

Rheumatoid arthritis (RA) is a chronic inflammatory autoimmune disease which affects about 0.5-1% of people with symptoms that significantly impact a sufferer's lifestyle. The cells involved in propagating RA tend to display pro-inflammatory and cancer-like characteristics. Medical drug treatment is currently the main avenue of RA therapy. However, drug options are limited due to severe side effects, high costs, insufficient disease retardation in a majority of patients, and therapeutic effects possibly subsiding over time. Thus there is a need for new drug therapies. Endoplasmic reticulum (ER) stress, a condition due to accumulation of misfolded proteins in the ER, and subsequent cellular responses have been found to be involved in cancer and inflammatory pathologies, including RA. ER stress protein markers and their modulation have therefore been suggested as therapeutic targets, such as GRP78 and CHOP, among others. Some current RA therapeutic drugs have been found to have ER stress-modulating properties. Traditional Chinese Medicines (TCMs) frequently use natural products that affect multiple body and cellular targets, and several medicines and/or their isolated compounds have been found to also have ER stress-modulating capabilities, including TCMs used in RA treatment by Chinese Medicine practitioners. This review encourages, in light of the available information, the study of these RA-treating, ER stress-modulating TCMs as potential new pharmaceutical drugs for use in clinical RA therapy, along with providing a list of other ER stress-modulating TCMs utilized in treatment of cancers, inflammatory diseases and other diseases, that have potential use in RA treatment given similar ER stress-modulating capacity.

The complex interplay between endoplasmic reticulum stress and the NLRP3 inflammasome: a potential therapeutic target for inflammatory disorders

Inflammation is the result of a complex network of cellular and molecular interactions and mechanisms that facilitate immune protection against intrinsic and extrinsic stimuli, particularly pathogens, to maintain homeostasis and promote tissue healing. However, dysregulation in the immune system elicits excess/abnormal inflammation resulting in unintended tissue damage and causes major inflammatory diseases including asthma, chronic obstructive pulmonary disease, atherosclerosis, inflammatory bowel diseases, sarcoidosis and rheumatoid arthritis. It is now widely accepted that both endoplasmic reticulum (ER) stress and inflammasomes play critical roles in activating inflammatory signalling cascades. Notably, evidence is mounting for the involvement of ER stress in exacerbating inflammasome-induced inflammatory cascades, which may provide a new axis for therapeutic targeting in a range of inflammatory disorders. Here, we comprehensively review the roles, mechanisms and interactions of both ER stress and inflammasomes, as well as their interconnected relationships in inflammatory signalling cascades. We also discuss novel therapeutic strategies that are being developed to treat ER stress- and inflammasome-related inflammatory disorders.

Bilirubin Attenuates ER Stress-Mediated Inflammation, Escalates Apoptosis and Reduces Proliferation in the LS174T Colonic Epithelial Cell Line

Mildly elevated serum unconjugated bilirubin (UCB) concentrations are associated with protection against disease conditions underpinned by cellular and metabolic stress. To determine the potential therapeutic efficacy of UCB we tested it in an in vitro model of gut inflammation. Tunicamycin TUN (10 µg/mL) was used to induce endoplasmic reticular stress (ERS) affecting N-glycosylation in LS174T cells. Cultured cells were investigated with addition of UCB at doses 0.1, 1 and 10µM (resulting in bilirubin:albumin ratios of 0.325-0.003)against ER stress-mediated effects including inflammation, cell survival (determined by apoptosis) and proliferation. Gene expression of ER stress markers (Grp78, Perk, XBP1 and ATF6) were evaluated in addition to cytokine concentrations in media after six hours of treatment. We then verified the potential role of UCB in executing programmed cell death via PARP, Caspase3 and Annexin V assays and further explored cell proliferation using the Click-iT EdU assay. A dose of 10µM UCB most potently reduced tunicamycin-mediated effects on enhanced UPR markers, inflammatory cytokines and proliferation; however all the doses (i.e.0.1-10µM) reduced the expression of ER stress and inflammatory markers Grp78, NLRP3, IL1-b, XBP1, PERK and ATF6. Furthermore, media concentrations of pro-inflammatory cytokines IL-8, IL-4 and TNFα decreased and the anti-inflammatory cytokine IL-10 increased (P<0.05). A dose of 10µM UCB initiated intrinsic apoptosis via Caspase 3 and in addition reduced cellular proliferation. Collectively, these data indicate that co treatment with UCB resulted in reducing ER stress response to TUN in gastrointestinal epithelial cells, reduced the subsequent inflammatory response, induced cancer cell death and decreased cellular proliferation. These data suggest that mildly elevated circulating or enteric UCB might protect against gastrointestinal inflammatory disorders.

FKBP11 protects intestinal epithelial cells against inflammation‑induced apoptosis via the JNK‑caspase pathway in Crohn's disease

Endoplasmic reticulum (ER) stress in intestinal epithelial cells (IECs) has an important role in the pathogenesis of Crohn's disease (CD). FK506 binding protein 11 (FKBP11), a member of the peptidyl‑prolyl cis‑trans isomerase family, is involved in the unfolded protein response (UPR) and is closely associated with inflammation. Previous bioinformatics analysis revealed a potential association between FKBP11 and human CD. Thus, the present study aimed to investigate the potential significance of FKBP11 in IEC homeostasis and CD. In the present study, increased expression of FKBP11 was detected in the intestinal inflammatory tissues of patients with CD. Furthermore, the results of the present study revealed that overexpression of FKBP11 was accompanied by increased expression levels of the ER stress marker 78 kDa glucose‑regulated protein in the colon tissues of a 2, 4, 6‑trinitrobenzenesulphonic acid‑induced mouse colitis model. Using interferon‑γ (IFN‑γ)/tumor necrosis factor‑α (TNF‑α)‑stimulated IECs as an ER stress and apoptosis cell model, the associated of FKBP11 with ER stress and apoptosis levels was confirmed in IECs. Overexpression of FKBP11 was revealed to significantly attenuate the elevated expression of pro‑apoptotic proteins (Bcl2 associated X apoptosis regulator, caspase‑12 and active caspase‑3), suppress the phosphorylation of c‑Jun N‑terminal kinase (JNK), and decrease apoptosis of IFN‑γ/TNF‑α stimulated IECs. Knockdown of FKBP11 by transfection with small interfering RNA further validated the aforementioned results. In conclusion, these results suggest that the UPR protein FKBP11 may protect IECs against IFN‑γ/TNF‑α induced apoptosis by inhibiting the ER stress‑associated JNK/caspase apoptotic pathway in CD.

Bitter melon extract ameliorates palmitate-induced apoptosis via inhibition of endoplasmic reticulum stress in HepG2 cells and high-fat/high-fructose-diet-induced fatty liver

Background

Bitter melon (BM) improves glucose level, lipid homeostasis, and insulin resistance in vivo. However, the preventive mechanism of BM in nonalcoholic fatty liver disease (NAFLD) has not been elucidated yet.

Aim & Design

To determine the protective mechanism of bitter melon extract (BME), we performed experiments in vitro and in vivo. BME were treated palmitate (PA)-administrated HepG2 cells. C57BL/6J mice were divided into two groups: high-fat/high-fructose (HF/HFr) without or with BME supplementation (100 mg/kg body weight). Endoplasmic reticulum (ER) stress, apoptosis, and biochemical markers were then examined by western blot and real-time PCR analyses.

Results

BME significantly decreased expression levels of ER-stress markers (including phospho-eIF2α, CHOP, and phospho-JNK [Jun N-terminal kinases]) in PA-treated HepG2 cells. BME also significantly decreased the activity of cleaved caspase-3 (a well known apoptotic-induced molecule) and DNA fragmentation. The effect of BME on ER stress-mediated apoptosis in vitro was similarly observed in HF/HFr-fed mice in vivo. BME significantly reduced HF/HFr-induced hepatic triglyceride (TG) and serum alanine aminotransferase (ALT) as markers of hepatic damage in mice. In addition, BME ameliorated HF/HFr-induced serum TG and serum-free fatty acids.

Conclusion

These data indicate that BME has protective effects against ER stress mediated apoptosis in HepG2 cells as well as in HF/HFr-induced fatty liver of mouse. Therefore, BME might be useful for preventing and treating NAFLD.

Obese rats supplemented with bitter melon display marked shifts in the expression of genes controlling inflammatory response and lipid metabolism by RNA-Seq analysis of colonic mucosa

Obesity is known to induce pathological changes in the gut and diets rich in complex carbohydrates that resist digestion in the small bowel can alter large bowel ecology. The purposes of this study were to identify the effects of bitter melon powder (BMP) on the global gene expression pattern in the colon mucosa of obese rats. Obese rats were fed a high-fat diet and treated without or with BMP for 8 weeks. Genome-wide expression profiles of the colon mucosa were determined by RNA sequencing (RNA-Seq) analysis at the end of experiment. A total of 87 genes were identified as differentially expressed (DE) between these two groups (fold change > 1.2). These results were further validated by quantitative RT-PCR, confirming the high reliability of the RNA-Seq. Interestingly, DE genes implicated in inflammation and lipid metabolism were found to be downregulated by BMP in the colon. Network between genes and the top 15 KEGG pathways showed that PRKCβ (protein kinase C beta) and Pla2g2a (phospholipase A2 group IIA) strongly interacted with surrounding pathways and genes. Results revealed that BMP supplement could remodel key colon functions by altering transcriptomic profile in obese rats.

Endoplasmic Reticulum Stress and Oxidative Stress: A Vicious Nexus Implicated in Bowel Disease Pathophysiology

The endoplasmic reticulum (ER) is a complex protein folding and trafficking organelle. Alteration and discrepancy in the endoplasmic reticulum environment can affect the protein folding process and hence, can result in the production of misfolded proteins. The accumulation of misfolded proteins causes cellular damage and elicits endoplasmic reticulum stress. Under such stress conditions, cells exhibit reduced functional synthesis, and will undergo apoptosis if the stress is prolonged. To resolve the ER stress, cells trigger an intrinsic mechanism called an unfolded protein response (UPR). UPR is an adaptive signaling process that triggers multiple pathways through the endoplasmic reticulum transmembrane transducers, to reduce and remove misfolded proteins and improve the protein folding mechanism, in order to improve and maintain endoplasmic reticulum homeostasis. An increasing number of studies support the view that oxidative stress has a strong connection with ER stress. During the protein folding process, reactive oxygen species are produced as by-products, leading to impaired reduction-oxidation (redox) balance conferring oxidative stress. As the protein folding process is dependent on redox homeostasis, the oxidative stress can disrupt the protein folding mechanism and enhance the production of misfolded proteins, causing further ER stress. It is proposed that endoplasmic reticulum stress and oxidative stress together play significant roles in the pathophysiology of bowel diseases.