Inhibition of endoplasmic reticulum stress by 4-phenylbutyric acid prevents vital organ injury in rat acute pancreatitis

Role and Mechanism of Endoplasmic Reticulum Stress in Mice Pancreatic Islet Dysfunction After Severe Burns

This study attempted to investigate the role and mechanism of endoplasmic reticulum (ER) stress in the islet dysfunction in mice after severe burns. C57BL/6 mice were randomly divided into the sham group, burn group, and burn+4-phenylbutyric acid (4-PBA) group. Mice were burned with full thickness of 30% total surface area (TBSA), and 4-PBA solution was intraperitoneally injected into mice in burn+4-PBA group. Glucose-stimulated insulin secretion (GSIS), Fasting blood glucose (FBG) and glucose tolerance were detected 24 hours post severe burns. The ER stress-related pathway markers immunoglobulin binding protein (BIP), X-box binding protein 1 (XBP1), phosphorylation-PKR-like ER kinase (p-PERK), phosphorylation-eukaryotic translation initiation factor 2α (p-eIF2α), CHOP, activating transcription factor 6 (ATF6), apoptosis-related protein Cleaved-Caspase 3, and islet cell apoptosis were measured. Mice were characterized with elevated FBG, decreased glucose tolerance and GSIS levels post severe burns. The expression of BIP, XBP1, p-PERK, p-eIF2α, CHOP, ATF6, Cleaved-Caspase 3, and islet cell apoptosis were increased significantly after severe burns. 4-PBA treatment contributed to decreased FBG, improved glucose tolerance, increased GSIS, inhibited islet ER stress, and reduced pancreatic islet cell apoptosis in mice post severe burns. ER stress occurs in islets of severely burned mice, which leads to increased apoptosis of islet cells, thus resulting in islet dysfunction.

Xenon postconditioning attenuates neuronal injury after spinal cord ischemia/reperfusion injury by targeting endoplasmic reticulum stress-associated apoptosis

The purpose of the study is to explore the underlying mechanisms of xenon (Xe) which protects against spinal cord ischemia/reperfusion injury (SCIRI). A SCIRI rat model was induced by abdominal artery occlusion for 85 min and reperfusion. Xe postconditioning (50% Xe) was administered 1 h after 1 h of reperfusion. At reperfusion time points (2, 4, 6, and 24 h), rats were treated with spinal cord scans by MRI to assess the time of peak spinal cord injury after SCIRI. Subsequently, endoplasmic reticulum (ER) stress inhibitor sodium 4-phenylbutyrate (4-PBA) was administered by daily intraperitoneal injection (50 mg/kg) for 5 days before SCIRI. At 4 h after reperfusion, motor function, immunofluorescence staining, hematoxylin and eosin (HE) staining, Nissl staining, TUNEL staining, real-time reverse transcription polymerase chain (RT-PCR) reaction, and western blot analyses were performed to investigate the protective effects of Xe against SCIRI. In the rat I/R model, spinal cord edema peaked at reperfusion 4 h. SCIRI activated ER stress, which was located in neurons. Xe postconditioning remarkably alleviated hind limb motor function, reduced neuronal apoptosis rate, increased the number of normal neurons, and inhibited the expression of ER stress-related protein in spinal cord. Furthermore, the administration of the ER stress inhibitor 4-PBA strongly decreased ER stress-induced apoptosis following SCIRI. Xe postconditioning inhibits ER stress activation, which contributes to alleviate SCIRI by suppressing neuronal apoptosis.

Chronic obstructive pulmonary disease and emerging ER stress-related therapeutic targets

COPD pathogenesis is frequently associated with endoplasmic reticulum stress (ER stress) progression. Targeting the major unfolded protein response (UPR) branches in the ER stress pathway may provide pharmacotherapeutic selection strategies for treating COPD and enable relief from its symptoms. In this study, we aimed to systematically review the potential role of the ER stress inhibitors of major UPR branches (IRE1, PERK, and ATF6) in COPD-related studies and determine the current stage of knowledge in this field. The systematic review was carried out adhering to the PRISMA checklist based on published studies obtained from specific keyword searches of three databases, namely PubMed, ScienceDirect and Springer Database. The search was limited to the year 2000-2022 which includes all in vitro studies, in vivo studies and clinical trials related to the application of ER stress inhibitors toward COPD-induced models and disease. The risk of bias was evaluated using the QUIN, SYRCLE, revised Cochrane risk of bias tool for randomized trials (RoB 2.0) and NIH tool respectively. A total of 7828 articles were screened from three databases and a final total of 37 studies were included in the review. The ER stress and UPR pathways are potentially useful to prevent COPD progression and attenuate the exacerbation of COPD and related symptoms. Interestingly, the off-target effects from inhibition of the UPR pathway may be desirable or undesirable depending on context and therapeutic applications. Targeting the UPR pathway could have complex consequences as the production of ER molecules involved in folding may be impaired which could continuously provoke misfolding of proteins. Although several emerging compounds were noted to be potentially useful for targeted therapy against COPD, clinical studies have yet to be thoroughly explored.

Endoplasmic reticulum stress promotes caspase-1-dependent acinar cell pyroptosis through the PERK pathway to aggravate acute pancreatitis

The purpose of this study was to explore whether and how endoplasmic reticulum stress (ERS) could promote caspase-1-dependent pancreatic acinar cell pyroptosis via the protein kinase R-like ER kinase (PERK) pathway to aggravate acute pancreatitis (AP). Wistar rats and AR42J cells were used to establish the AP model. When indicated, ERS regulation was performed prior to AP induction,and genetic regulation was performed prior to ERS induction. First, we found that caspase-1-dependent pyroptosis and pyroptotic injury were regulated by ERS in AP. By regulating three pathways in the UPR, ERS promotes caspase-1-dependent pyroptosis and pyroptotic injury through the PERK pathway. To further validate that ERS promotes caspase-1-dependent pyroptosis and pyroptotic injury through PERK, we used the PERK inhibitor ISRIB. In conclusion, our results indicated that ERS exacerbates AP by promoting caspase-1-dependent pyroptosis via the PERK pathway.

Endoplasmic reticulum stress inhibition ameliorated WFS1 expression alterations and reduced pancreatic islets' insulin secretion induced by high-fat diet in rats

Endoplasmic reticulum (ER) stress is involved in the development of glucose homeostasis impairment. When ER stress occurs, the unfolded protein response (UPR) is activated to cope with it. One of the UPR components is WFS1 (Wolfram syndrome 1), which plays important roles in ER homeostasis and pancreatic islets glucose-stimulated insulin secretion (GSIS). Accordingly and considering that feeding high-fat food has a major contribution in metabolic disorders, this study aimed to investigate the possible involvement of pancreatic ER stress in glucose metabolism impairment induced by feeding high-fat diet (HFD) in male rats. After weaning, the rats were divided into six groups, and fed on normal diet and HFD for 20 weeks, then 4-phenyl butyric acid (4-PBA, an ER stress inhibitor) was administered. Subsequently, in all groups, after performing glucose tolerance test, the animals were dissected and their pancreases were removed to extract ER, islets isolation and assessment of GSIS. Moreover, the pancreatic ER stress [binding of immunoglobulin protein (BIP) and enhancer-binding protein homologous protein (CHOP)] and oxidative stress [malondialdehyde (MDA), glutathione (GSH) and catalase] biomarkers as well as WFS1 expression level were evaluated. HFD decreased pancreatic WFS1 protein and GSH levels, and enhanced pancreatic catalase activity, MDA content, BIP and CHOP protein and mRNA levels as well as Wfs1 mRNA amount. Accordingly, it increased BIP, CHOP and WFS1 protein levels in the extracted ER of pancreas. In addition, the HFD caused glucose intolerance, and decreased the islets' GSIS and insulin content. However, 4-PBA administration restored the alterations. It seems that, HFD consumption through inducing pancreatic ER stress, altered WFS1 expression levels, reduced the islets' GSIS and insulin content and finally impaired glucose homeostasis.

The Role of 4-Phenylbutyric Acid in Gut Microbial Dysbiosis in a Mouse Model of Simulated Microgravity

The altered gut microbes of astronauts during space travel may contribute to health issues after their return to Earth. Previously, an association between the elevated endoplasmic reticulum (ER) stress and gut microbial dysbiosis has been described. Herein, we induced gut microbial changes in mice under a simulated microgravity environment in an established model of hindlimb unloaded (HU) mice. The intestinal metabolomic profiles under microgravity conditions using the HU model were examined, along with the potential role of 4-phenylbutyric acid (4-PBA), a potent ER stress inhibitor. For a microgravity environment, the mice were suspended in special cages individually for three weeks. Mice were sacrificed, and gut dissections were performed, followed by amplicon sequencing analysis of bacterial species via DNA extraction and 16S rRNA analysis. The results indicate that the gut bacterial communities of mice differed under gravity and microgravity conditions. Principal component analyses revealed differences in the bacterial community structure in all groups. Around 434 operational taxonomic units (OTUs) were specific to mice seen in controls, while 620 OTUs were specific to HU mice. Additionally, 321 bacterial OTUs were specific to HU mice treated with 4-PBA. When the relative abundance of taxa was analyzed, Bacteroidetes dominated the gut of control and HU mice treated with 4-PBA.. In contrast, the untreated HU mice were dominated by Firmicutes. At the genus level, a reduction in beneficial species of Akkermansia and Lactobacillus was observed in HU but not the unloaded–treated and control mice. Furthermore, an increase in the relative abundance of Lachnospiraceae and Enterorhabdus, associated with inflammation, was observed in HUmice but not in controls and unloaded-treated mice. Following treatment with 4-PBA, the ratio of Firmicutes to Bacteroidetes was restored in unloaded–treated mice, comparable to controls. Of note, beneficial microbes such as Akkermansia and Lactobacillus were observed in unloaded–treated mice but not or in lesser relative abundance in HU mice. Nonetheless, microbial diversity was reduced in unloaded–treated mice compared to controls, and future studies are needed to mitigate this finding. These may comprise the addition of pre-/pro- and postbiotic species in the diet to increase microbial diversity. Overall, the findings suggest that 4-PBA, a potent ER stress inhibitor, may have therapeutic value in treating patients on prolonged bed rest or astronauts during spaceflight.

Endoplasmic reticulum stress promoted acinar cell necroptosis in acute pancreatitis through cathepsinB-mediated AP-1 activation

Acinar cell death and inflammatory response are two important events which determine the severity of acute pancreatitis (AP). Endoplasmic reticulum (ER) stress and necroptosis are involved in this process, but the relationships between them remain unknown. Here, we analyzed the interaction between ER stress and necroptosis and the underlying mechanisms during AP. Experimental pancreatitis was induced in Balb/C mice by caerulein (Cae) and lipopolysaccharide (LPS) or L-arginine (L-Arg) in vivo, and pancreatic acinar cells were also used to follow cellular mechanisms during cholecystokinin (CCK) stimulation in vitro. AP severity was assessed by serum amylase, lipase levels and histological examination. Changes in ER stress, trypsinogen activation and necroptosis levels were analyzed by western blotting, enzyme-linked immunosorbent assay (ELISA), adenosine triphosphate (ATP) analysis or lactate dehydrogenase (LDH) assay. The protein kinase C (PKC)α -mitogen-activated protein kinase (MAPK) -cJun pathway and cathepsin B (CTSB) activation were evaluated by western blotting. Activating protein 1 (AP-1) binding activity was detected by electrophoretic mobility shift assay (EMSA). We found that ER stress is initiated before necroptosis in CCK-stimulated acinar cells in vitro. Inhibition of ER stress by 4-phenylbutyrate (4-PBA) can significantly alleviate AP severity both in two AP models in vivo. 4-PBA markedly inhibited ER stress and necroptosis of pancreatic acinar cells both in vitro and in vivo. Mechanistically, we found that 4-PBA significantly reduced CTSB maturation and PKCα-JNK-cJun pathway -mediated AP-1 activation during AP. Besides, CTSB inhibitor CA074Me markedly blocked PKCα-JNK-cJun pathway -mediated AP-1 activation and necroptosis in AP. However, pharmacologic inhibition of trypsin activity with benzamidine hydrochloride had no effect on PKCα-JNK-cJun pathway and necroptosis in CCK-stimulated pancreatic acinar cells. Furthermore, SR11302, the inhibitor of AP-1, significantly lowered tumor necrosis factor (TNF) α levels, and its subsequent receptor interacting protein kinases (RIP)3 and phosphorylated mixed lineagekinase domain-like (pMLKL) levels, ATP depletion and LDH release rate in CCK-stimulated pancreatic acinar cells. To sum up, all the results indicated that during AP, ER stress promoted pancreatic acinar cell necroptosis through CTSB maturation, thus induced AP-1 activation and TNFα secretion via PKCα-JNK-cJun pathway, not related with trypsin activity. These findings provided potential therapeutic target and treatment strategies for AP or other cell death-related diseases.

Targeting Endoplasmic Reticulum Stress as an Effective Treatment for Alcoholic Pancreatitis

Pancreatitis and alcoholic pancreatitis are serious health concerns with an urgent need for effective treatment strategies. Alcohol is a known etiological factor for pancreatitis, including acute pancreatitis (AP) and chronic pancreatitis (CP). Excessive alcohol consumption induces many pathological stress responses; of particular note is endoplasmic reticulum (ER) stress and adaptive unfolded protein response (UPR). ER stress results from the accumulation of unfolded/misfolded protein in the ER and is implicated in the pathogenesis of alcoholic pancreatitis. Here, we summarize the possible mechanisms by which ER stress contributes to alcoholic pancreatitis. We also discuss potential approaches targeting ER stress and UPR in developing novel therapeutic strategies for the disease.

Liver injury associated with acute pancreatitis: The current status of clinical evaluation and involved mechanisms

Acute pancreatitis (AP) is a very common acute disease, and the mortality rate of severe AP (SAP) is between 15% and 35%. The main causes of death are multiple organ dysfunction syndrome and infections. The mortality rate of patients with SAP related to liver failure is as high as 83%, and approximately 5% of the SAP patients have fulminant liver failure. Liver function is closely related to the progression and prognosis of AP. In this review, we aim to elaborate on the clinical manifestations and mechanism of liver injury in patients with AP.

System Analysis of ROS-Related Genes in the Prognosis, Immune Infiltration, and Drug Sensitivity in Hepatocellular Carcinoma

Hepatocellular carcinoma (HCC) is an aggressive malignant tumor with a poor prognosis. Reactive oxygen species (ROS) play an important role in tumors; however, the role of ROS-related genes is still unclear in HCC. Therefore, we analyzed the role of ROS-related genes in HCC via bioinformatics methods. Firstly, a prognosis model was constructed using LASSO Cox regression and multivariate analyses. We also investigated the potential function of the ROS-related genes and the correlation with immune infiltration, tumor stemness, and drug sensitivity. ICGC database was used for validation. Secondly, we further analyzed the role of 11 ROS-related genes in HCC. As a member of ROS gene family, the role of STK25 has remained unclear in HCC. We explored the biological function of STK25 using in vitro experiments. The present study was the first to construct a ROS-related prognostic model in HCC. The correlation of ROS-related genes with immune infiltration, tumor stemness, and drug sensitivity was dissected. Furthermore, we demonstrated that STK25 knockdown could increase the proliferation, migration, and invasion capacity of HCC cells.

4-Phenylbutyric acid accelerates rehabilitation of barrier function in IPEC-J2 cell monolayer model

As the first line of defence against pathogens and endotoxins crossing the intestine-blood barrier, the intestinal epithelial barrier plays a determinant role in pigs' health and growth. 4-Phenylbutyric acid (4-PBA), an aromatic fatty acid, was reported to benefit homeostasis of endoplasmic reticulum and protein synthesis. However, whether 4-PBA affects intestinal epithelial barrier function in pigs is unknown. This study aimed to explore the effects of 4-PBA on the intestinal barrier function, using in vitro models of well-differentiated intestinal porcine epithelial cell (IPEC-J2) monolayers in the transwell plates. Cell monolayers with or without 4-PBA (1.0 mmol/L) treatment were challenged with physical scratch, deoxynivalenol (DON, 2.0 μg/mL, 48 h), and lipopolysaccharide (LPS, 5.0 μg/mL, 48 h), respectively. Transepithelial electrical resistance (TEER) and fluorescein isothiocyanate-dextran (FD-4) permeability were measured to indicate barrier integrity and permeability. Real-time PCR and Western blot were conducted to determine relative gene and protein expressions of tight junction proteins. As expected, physical scratch, DON, and LPS challenges decreased TEER and increased FD-4 permeability. 4-PBA treatment accelerated cell mitigation and rehabilitation of the physical scratch-damaged intestinal epithelial barrier but did not alleviate DON or LPS induced barrier damage. However, once 48-h DON and LPS challenges were removed, rehabilitation of the epithelial barrier function of IPEC-J2 monolayer was accelerated by the 4-PBA treatment. Also, the relative gene and protein expressions of zonula occludens-1 (ZO-1), occludin, and claudin-1 were further upregulated by the 4-PBA treatment during the barrier rehabilitation. Taken together, 4-PBA accelerated the IPEC-J2 cell monolayer barrier recovering from physical scratch, DON-, and LPS-induced damage, via enhancing cell mitigation and expressions of tight junction proteins.

ADAM15 correlates with prognosis, immune infiltration and apoptosis in hepatocellular carcinoma

ADAM15 is highly expressed in malignant tumors and is correlated with tumor progression. However, the role of ADAM15 in hepatocellular carcinoma (HCC) remains unclear. In the study, our results indicated that ADAM15 was highly expressed in HCC tissues and cells compared with corresponding tissues and liver cells. Overexpression of ADAM15 was linked to poor prognosis, and was an independent risk factor for HCC prognosis. Besides, analysis of immune infiltration indicated that ADAM15 expression was related to tumor infiltrating lymphocytes based on the TIMER, TISIDB and GEPIA databases. Many immune checkpoint gene expression was associated with ADAM15 expression. Functional enrichment analyses indicated that apoptosis, cell adhesion was enriched. ADAM15 knockdown promoted apoptosis and suppressed proliferation, migration and invasion of liver cancer cells. The findings of western blot showed that ADAM15 knockdown reduced the expression of Bcl-2, Vimentin, N-Cadherin and Snail, and elevated the expression of Bax, E-cadherin and ZO-1. However, overexpression of ADAM15 had the opposite results. Collectively, our findings demonstrated that ADAM15 was connected with poor prognosis of HCC patients, and could be considered as a potential biomarker for the diagnosis and treatment of HCC.

The chemical chaperon 4-phenyl butyric acid restored high-fat diet- induced hippocampal insulin content and insulin receptor level reduction along with spatial learning and memory deficits in male rats

This study assessed the effect of a chronic high-fat diet (HFD) on plasma and hippocampal insulin and corticosterone levels, the hippocampus insulin receptor amount, and spatial learning and memory with or without receiving 4-phenyl butyric acid (4-PBA) in male rats. Rats were divided into high-fat and normal diet groups, then each group was subdivided into dimethyl sulfoxide (DMSO) and 4-PBA groups. After weaning, the rats were fed with HFD for 20 weeks. Then, 4-PBA or DMSO were injected for 3 days. Subsequently, oral glucose tolerance test was done. On the following day, spatial memory tests were performed. Then the hippocampus Bip, Chop, insulin, corticosterone, and insulin receptor levels were determined. HFD increased plasma glucose, leptin and corticosterone concentrations, hippocampus Bip, Chop and corticosterone levels, food intake, abdominal fat weight and body weight along with impaired glucose tolerance. It decreased plasma insulin, and insulin content, and its receptor amount in hippocampus. HFD lengthened escape latency and shortened the duration spent in target zone. 4-PBA administration improved the HFD- induced adverse changes. Chronic HFD possibly through the induction of endoplasmic reticulum (ER) stress and subsequent changes in the levels of hippocampal corticosterone, insulin and insulin receptor along with possible leptin resistance caused spatial learning and memory deficits.

The Role of Pancreatic Infiltrating Innate Immune Cells in Acute Pancreatitis

Acute pancreatitis (AP) is a leading cause of gastrointestinal-related hospital admissions with significant morbidity and mortality. Although the underlying pathophysiology of AP is rather complex, which greatly limits the treatment options, more and more studies have revealed that infiltrating immune cells play a critical role in the pathogenesis of AP and determine disease severity. Thus, immunomodulatory therapy targeting immune cells and related inflammatory mediators is expected to be a novel treatment modality for AP which may improve the prognosis of patients. Cells of the innate immune system, including macrophages, neutrophils, dendritic cells, and mast cells, represent the majority of infiltrating cells during AP. In this review, an overview of different populations of innate immune cells and their role during AP will be discussed, with a special focus on neutrophils and macrophages.

Inhibition of endoplasmic reticulum stress prevents high-fat diet mediated atrial fibrosis and fibrillation

Obesity is a significant risk factor for atrial fibrillation (AF), which is the most common sustained arrhythmia with increased mortality and morbidity. High-fat diet (HFD)-induced obesity is associated with the activation of endoplasmic reticulum stress (ERS). However, the role of ERS in HFD-induced AF remains elusive. Human atrium samples were examined for the ERS activation test. C57BL/6J mice were divided into four groups, including the control group, the HFD group, the 4-phenylbutyric acid (4-PBA) group, and the HFD + 4-PBA group. At the age of 4 weeks, the HFD group and the HFD + 4-PBA group were given HFD to construct the obesity model, while the other two groups were given a normal diet (ND). Transesophageal programmed electrical stimulation was conducted to evaluate the AF inducibility and duration. Atrial fibrosis and ERS activation were also investigated.We found that CHOP and GRP-78 protein were significantly higher in overweight patients than the controls (both P < 0.05). AF inducibility and duration of the HFD group were significantly higher than the other groups (both P < 0.05), while there was no difference between those groups (P > 0.05). The mice of the HFD group had significantly higher collagen volume fraction (CVF%) than the other groups (P < 0.05). ERS marker protein of GRP78, p-PERK, ATF6 and CHOP protein expression level was increased in the HFD group, which were significantly mitigated in the HFD + 4-PBA group. In summary, HFD-induced ERS activation facilitates atrial fibrosis and AF. The inhibition of ERS might alleviate atrial fibrosis and reduce the incidence of AF-associated obesity.

Nonsteroidal anti-inflammatory drugs alleviate severity of post-endoscopic retrograde cholangiopancreatography pancreatitis by inhibiting inflammation and reducing apoptosis

BACKGROUND AND AIM

The prophylactic effect of nonselective nonsteroidal anti-inflammatory drugs on post-ERCP (endoscopic retrograde cholangiopancreatography) pancreatitis has been observed for a long time. However, whether the selective nonsteroidal anti-inflammatory drugs possess similar abilities and the mechanisms by which nonsteroidal anti-inflammatory drugs work remain unclear. The present study aimed to determine the protective effects of nonsteroidal anti-inflammatory drugs on post-ERCP pancreatitis in a rat model and examine underlying mechanisms.

METHODS

Thirty-two female rats were equally and randomly divided into four groups: the sham group, post-ERCP pancreatitis model group, indomethacin-pretreated group, and parecoxib-pretreated group. Indomethacin or parecoxib was delivered 30 min prior to surgery; 24 h after post-ERCP pancreatitis establishment, the rats were sacrificed. Serum amylase and lipase activities, inflammatory cytokine release, pancreatic histopathological scores, neutrophil infiltration, and the expression pattern cyclooxygenase at the protein level and pancreatic apoptosis were quantified and analyzed.

RESULTS

Both indomethacin and parecoxib inhibited the activities of serum amylase and lipase and reduced the severity of pancreatic histopathology. Mechanistically, both drugs decreased the expression level of cyclooxygenase 2; however, they had no influence on the cyclooxygenase 1 protein level. Moreover, they reduced inflammatory cytokine release, neutrophil infiltration into the pancreas, and NF-κB p65 activation. Notably, we found that apoptotic cells in the pancreas were remarkably diminished after the administration of both nonsteroidal anti-inflammatory drugs.

CONCLUSIONS

Both selective and nonselective nonsteroidal anti-inflammatory drugs exert protective effects against post-ERCP pancreatitis by restraining inflammation and reducing acinar cell apoptosis through the inhibition of cyclooxygenase 2.

Chaiqin chengqi decoction alleviates severe acute pancreatitis associated acute kidney injury by inhibiting endoplasmic reticulum stress and subsequent apoptosis

BACKGROUND

Acute kidney injury (AKI), characterized by an increase of serum creatinine and urea, is a severe complication of severe acute pancreatitis (SAP) with high mortality. Endoplasmic reticulum (ER) stress has been considered as a key pathologic process in AKI. Chaiqin chengqi decoction (CQCQD) is an effective Chinese medicine formula for SAP treatment in China and has been used for many years. Our goal is to explore the role of CQCQD on ER stress of AKI in experimental SAP.

MATERIALS & METHODS

SAP was induced in rats by retrograde duct injection of 5% sodium taurocholate (NaTC, 1 ml/kg), sham operation (SO) rats simultaneously received saline infusion. Intraperitoneal injection of 4-PBA (50 mg/kg, once a day for three days before the surgery) or intragastric gavage of CQCQD (1 g/kg, 2 hourly × 3 after disease induction) was used to treat SAP rats. All animals were humanely sacrificed 12 h after disease induction. Histopathology scores of kidney and pancreas; serum biochemical indices and kidney protein levels of ER stress and apoptosis markers were assessed. Tubular epithelial cell line (HK-2) was treated either with TNF-α (10 ng/ml) or IL-6 (10 ng/ml) for 12 h plus either 4-PBA (0.1 M) or CQCQD (1 mg/ml) for in vitro study. Cell viability and markers of ER stress and apoptosis were measured.

RESULTS

Ductal perfusion of NaTC caused significant increases in serum lipase, amylase and pancreatic histopathology (inflammatory cell infiltration, interstitial edema, and acinar cell necrosis). Kidney histopathology (tubular dilation, brush border loss, little tubular necrosis, and cast formation), serum creatine and urea levels were raised when compared with the SO group. Moreover, apoptotic cell death markers (caspase-9, cleaved-caspase-3, and TUNEL) and kidney ER stress proteins (BIP, IRE1-α, XBP1s, and CHOP) were elevated after NaTC administration. 4-PBA and CQCQD significantly alleviated histopathological changes of kidney and pancreas, inflammatory cytokines, biochemical markers of AKI, ER stress proteins and apoptotic cell death markers. They also protected HK-2 cells from injury of TNF-α and IL-6, and alleviated both ER stress and apoptosis proteins in vitro.

CONCLUSION

CQCQD may alleviate SAP-related AKI by inhibiting ER stress-related apoptosis.

High-Fat Diet Aggravates Acute Pancreatitis via TLR4-Mediated Necroptosis and Inflammation in Rats

High-fat diet (HFD) often increases oxidative stress and enhances inflammatory status in the body. Toll-like receptor 4 (TLR4) is widely expressed in the pancreatic tissues and plays an important role in pancreatitis. This study is aimed at investigating the effect of HFD on acute pancreatitis (AP) and the role of TLR4-mediated necroptosis and inflammation in this disease. Weight-matched rats were allocated for an 8-week feeding on the standard chow diet (SCD) or HFD, and then, the AP model was induced by infusion of 5% sodium taurocholate into the biliopancreatic duct. Rats were sacrificed at an indicated time point after modeling. Additionally, inhibition of TLR4 signaling by TAK-242 in HFD rats with AP was conducted in vivo. The results showed that the levels of serum free fatty acid (FFA) in HFD rats were higher than those in SCD rats. Moreover, HFD rats were more vulnerable to AP injury than SCD rats, as indicated by more serious pathological damage and much higher pancreatic malondialdehyde (MDA) and lipid peroxidation (LPO) levels as well as lower pancreatic superoxide dismutase (SOD) activities and reduced glutathione (GSH) contents and more intense infiltration of MPO-positive neutrophils and CD68-positive macrophages. In addition, HFD markedly increased the expressions of TLR4 and necroptosis marker (RIP3) and aggravated the activation of NF-κB p65 and the expression of TNF-α in the pancreas of AP rats at indicated time points. However, TLR4 inhibition significantly attenuated the structural and functional damage of the pancreas induced by AP in HFD rats, as indicated by improvement of the above indexes. Taken together, these findings suggest that HFD exacerbated the extent and severity of AP via oxidative stress, inflammatory response, and necroptosis. Inhibition of TLR4 signaling by TAK-242 alleviated oxidative stress and decreased inflammatory reaction and necroptosis, exerting a protective effect during AP in HFD rats.

High-Fat Diet Aggravates the Intestinal Barrier Injury via TLR4-RIP3 Pathway in a Rat Model of Severe Acute Pancreatitis

OBJECTIVE

For patients with severe acute pancreatitis (SAP), a high body mass index (BMI) increases the possibility of infection derived from the intestine. In this study, we evaluate whether TAK242 can alleviate severe acute pancreatitis-associated injury of intestinal barrier in high-fat diet-fed rats.

METHODS

A SAP model was established by retrograde injection of 5% sodium taurocholate into the biliary-pancreatic duct. Thirty Sprague-Dawley (SD) adult rats were randomly divided into five groups: standard rat chow (SRC) normal (SN), SRC SAP (SAP), high-fat diet normal (HN), HFD SAP (HSAP), and TLR4 inhibitor pretreatment HFD SAP (HAPT) groups. Intraperitoneal injection of 3 mg/kg TAK242 was administered 30 minutes before SAP model establishment in the HAPT group. Rats were sacrificed 12 hours after SAP modeling, followed by blood and pancreatic and distal ileum tissue collection for further analyses. Changes in the pathology responses of the rats in each group were assessed.

RESULT

Analyses of serum amylase, lipase, cholesterol, triglyceride, IL-1β, IL-6, DAO, and serum endotoxin as well as tight junction protein expression including zonula occluden-1 and occludin indicated that high-fat diet aggravated SAP-induced intestinal barrier injury via increasing inflammatory response. In addition, the level of necroptosis was significantly higher in the SAP group compared with the SN group while the HSAP group exhibited more necroptosis compared with the SAP group, indicating the important role of necroptosis in pancreatitis-associated gut injury and illustrating that high-fat diet aggravated necroptosis of the ileum. Pretreatment with TLR4 inhibitor significantly alleviated inflammatory response and reduced necroptosis and level of oxidative stress while improving intestinal barrier function.

CONCLUSION

High-fat diet aggravated SAP-induced intestinal barrier injury via inflammatory reactions, necroptosis, and oxidative stress. Inhibition of TLR4 by TAK242 reduced inflammation, alleviated necroptosis, and lowered the level of oxidative stress and then protected the intestinal barrier dysfunction from SAP in high-fat diet-fed rats.

Acetaldehyde Induces Neurotoxicity In Vitro via Oxidative Stress- and Ca2+ Imbalance-Mediated Endoplasmic Reticulum Stress

Excessive drinking can damage brain tissue and cause cognitive dysfunction. Studies have found that the early stage of neurodegenerative disease is closely related to heavy drinking. Acetaldehyde (ADE) is the main toxic metabolite of alcohol. However, the exact mechanisms of ADE-induced neurotoxicity are not fully clear. In this article, we studied the cytotoxic effect of ADE in HT22 cells and primary cultured cortical neuronal cells. We found that ADE exhibited cytotoxicities against HT22 cells and primary cultured cortical neuronal cells in dose-dependent manners. Furthermore, ADE induced apoptosis of HT22 cells by upregulating the expression of caspase family proapoptotic proteins. Moreover, ADE treatment could significantly increase the intracellular Ca²⁺ and reactive oxygen species (ROS) levels and activate endoplasmic reticulum stress (ERS) in HT22 cells. ADE upregulated ERS-related CHOP expression dose-dependently in primary cultured cortical neuronal cells. In addition, inhibition of ROS with antioxidant N-acetyl-L-cysteine (NAC) reduced the accumulation of ROS and reversed ADE-induced increase of ERS-related protein and apoptosis-related protein levels. Mitigation of ERS with ERS inhibitor 4-PBA obviously suppressed ADE-induced apoptosis and the expression of ERS-related proteins. Therefore, ADE induces neurotoxicity of HT22 cells via oxidative stress- and Ca²⁺ imbalance-mediated ERS.

Sodium Phenylbutyrate Ameliorates Inflammatory Response Induced by Staphylococcus aureus Lipoteichoic Acid via Suppressing TLR2/NF-κB/NLRP3 Pathways in MAC-T Cells

This study aimed to investigate the anti-inflammatory properties of sodium phenylbutyrate (SPB) against Staphylococcus aureus (S. aureus) lipoteichoic acid (LTA)-stimulated bovine mammary alveolar (MAC-T) cells. Quantitative PCR was performed to examine the effect of SPB on inflammatory cytokines and host defense peptide (HDP) gene expression. Western blot wanalysis was used to detect the effect of SPB on the TLR2/NF-κB/NLRP3 signaling pathway. The results showed that SPB significantly suppressed the expression of TNF-α, IL-1β, IL-6; meanwhile, the markedly decreased expression of LTA-stimulated TLR2, NLRP3, ASC, caspase-1, and IL-1β, and the inhibited IkBα and p65 phosphorylation were also observed. However, increased TAP and Bac5 expression in LTA-stimulated MAC-T cells was further detected. In summary, these results suggest that SPB ameliorates the inflammatory response induced by S. aureus LTA via suppressing the TLR2/NF-κB/NLRP3 signaling pathway, which indicates that SPB may be a potential agent for the treatment of bovine mastitis.