Increased heat-shock protein 90 expression contributes to impaired adaptive cytoprotection in the gastric mucosa of portal hypertensive rats

Changes of Short-Chain Fatty Acids and Their Receptors in an Obese Rat Model After Sleeve Gastrectomy

BACKGROUND

Short-chain fatty acids (SCFAs) and gut microbiota have health-related effects and are associated with a wide range of disorders. However, the changes of SCFAs and their receptors after sleeve gastrectomy (SG) remain unclear. This study aimed to examine changes of SCFAs and their receptors after SG in an obese rat model.

METHODS

Thirty obese Sprague-Dawley rats eating a high-energy diet for 6 weeks were divided into three groups: sham-operated (SO) control, pair-fed (PF) control, and SG group. Six weeks after the surgery, metabolic parameters, SCFA levels in the blood and stool, mRNA and protein expression of SCFA receptors in the ileum and epididymal fat, and gut microbiota were examined.

RESULTS

Metabolic parameters in the SG group were significantly improved compared with the SO group. Acetic acid levels in the blood and stool were significantly higher in the SG group than the PF group. The butyric acid level in the stool was also significantly higher in the SG group than in the PF group. In the ileum and epididymal fat, mRNA and protein expression of GPR41 was significantly higher in the SG group than in the other two groups, and mRNA and protein expression of GPR43 was significantly higher in the SG group than in the PF group. Increases in the genera Enterococcus, Lactobacillus, Lactococcus, and Clostridium were observed in the stool after SG.

CONCLUSIONS

SG may activate SCFA pathways through a change in gut microbiota.

Effects of sleeve gastrectomy and gastric banding on the hypothalamic feeding center in an obese rat model

PURPOSE

Laparoscopic sleeve gastrectomy (SG) and gastric banding (GB) are popular bariatric procedures for treating morbid obesity. This study aimed to investigate changes in the hypothalamic feeding center after these surgeries in a diet-induced obese rat model.

METHODS

Obesity was induced in 60 Sprague-Dawley rats using a high-energy diet for 6 weeks. These rats were divided into four groups: the sham-operated (SO) control, pair-fed (PF) control, SG and GB groups. Six weeks after the surgery, metabolic parameters, the plasma levels of leptin, ghrelin, peptide YY (PYY) and glucagon-like peptide-1 (GLP-1) and the hypothalamic mRNA expressions of neuropeptide Y (NPY) and pro-opiomelanocortin (POMC) were measured.

RESULTS

Compared with those observed in the SO group, the body and fat tissue weights were significantly decreased and the metabolic parameters were significantly improved in the PF, SG and GB groups 6 weeks after surgery. The plasma ghrelin levels were significantly lower and the PYY and GLP-1 levels were significantly higher in the SG group than in the PF, GB and SO groups. Compared with that seen in the PF and GB groups, the hypothalamic mRNA expression of NPY was significantly lower and the expression of POMC was significantly higher in the SG group.

CONCLUSIONS

SG may affect the neurological pathway associated with appetite in the hypothalamus and thereby control ingestive behavior.

Effects of sleeve gastrectomy on lipid metabolism in an obese diabetic rat model

BACKGROUND

Laparoscopic sleeve gastrectomy (SG) is a popular bariatric procedure for treating morbid obesity. This study aimed to investigate the relation between SG and lipid metabolism in an obese diabetic rat model.

METHODS

Forty-five male Zucker diabetic fatty (ZDF) rats were divided into three groups: sham-operated (SO) control, gastric banding (GB), and SG. Six weeks after surgery, metabolic parameters, including plasma adiponectin level, small bowel transit, mRNA expression of peroxisome proliferator-activated receptor (PPAR)-α and PPARγ in the liver, skeletal muscle and white adipose tissue, and that of adiponectin in white adipose tissue, and triglyceride (TG) contents in the liver and skeletal muscle were measured.

RESULTS

Metabolic parameters in the GB and SG groups were significantly improved compared with those in the SO group. However, plasma total cholesterol (TC) and free fatty acid (FFA) concentrations were significantly lower while the plasma adiponectin level was significantly higher in the SG group than in the GB and SO groups. In addition, small bowel transit time was significantly shorter in the SG group than in the other two groups. Furthermore, in the SG group, mRNA expression of PPARα in the liver and skeletal muscle and that of adiponection and PPARγ in white adipose tissue were significantly higher, while TG in the liver and skeletal muscle were significantly lower, compared with those in the other two groups.

CONCLUSIONS

These results suggest that SG improves lipid metabolism compared with GB, although there were no significant differences in the effect on weight loss between the two procedures.

Increased oxidative stress may lead to impaired adaptive cytoprotection in the gastric mucosa of portal hypertensive rat

BACKGROUND AND AIMS

In the gastric mucosa of portal hypertensive rats, adaptive cytoprotection against ethanol-induced damage is impaired. The aim of this study was to determine relation between impaired adaptive cytoprotection and oxidative stress.

METHODS

Portal hypertension was produced in male Sprague-Dawley rats by inducing staged portal vein occlusion. Oxidative stress levels were evaluated by measuring malondialdehyde and nitrotyrosine levels in the rat gastric mucosa with or without 10% ethanol pretreatment. Inhibition of oxidative stress by an anti-oxidant agent was estimated, and glutathione levels were also measured. Adaptive cytoprotection to 70% ethanol treatment was evaluated by measuring the gastric mucosal injury index in the presence or absence of the anti-oxidant.

RESULTS

The portal hypertensive gastric mucosa pretreated with 10% ethanol had significantly higher oxidative stress levels than the mucosa not pretreated with 10% ethanol. However, the sham-operated gastric mucosa pretreated with 10% ethanol had significantly lower oxidative stress levels than the mucosa not pretreated with 10% ethanol. Pretreatment with 10% ethanol increased glutathione levels in the sham-operated but not in the portal hypertensive gastric mucosa. Administration of the anti-oxidant agent prior to 10% ethanol pretreatment significantly reduced oxidative stress levels, increased glutathione levels, and decreased the injury index in response to 70% ethanol in the portal hypertensive gastric mucosa.

CONCLUSION

Increased oxidative stress may lead to impaired adaptive cytoprotection in the gastric mucosa of portal hypertensive rats, probably through damage to the system of endogenous anti-oxidant production.

The -144C/A polymorphism in the promoter of HSP90beta is associated with multiple organ dysfunction scores

Introduction

Variations in genetic background are the leading cause of differential susceptibility to traumatic infection. Heat shock protein 90 (HSP90), a broadly distributed and conserved molecule, regulates inflammation under stressful and traumatic conditions. However, the relationships between HSP90 genetic polymorphisms, post-traumatic inflammatory responses and organ function remain unknown.

Methods

A total of 286 healthy volunteers and patients with severe trauma took part in a single nucleotide polymorphism (SNP)-based analysis of the HSP90beta gene and a clinical association analysis. HSP90beta and TNF-alpha levels were determined using quantitative PCR and western blot. The transcriptional activity of the HSP90beta promoter was assayed using the Dual-Luciferase Reporter Assay System.

Results

The minor allele frequencies for the SNP located at −144 bp relative to the HSP90beta transcriptional start site were 28.47% and 28.52% in the normal and trauma populations, respectively; no significant differences were found between these two distributions. However, the results showed that a promoter containing the -144A allele had a higher transcriptional activity than did a promoter containing the wild-type -144C allele. Furthermore, the -144A promoter induced high expression of HSP90beta and low expression of the inflammatory factor TNF-alpha in a lipopolysaccharide-induced inflammatory model. A clinical association analysis showed that the multiple organ dysfunction scores for -144AA genotype carriers were significantly lower than those of -144CC carriers following trauma. No significant correlations were found between the presence of the two alleles and the incidence of sepsis.

Conclusions

These results indicate that differences in expression caused by the -144 polymorphism in the HSP90beta promoter are associated with cellular inflammatory responses and the severity of organ injury. These findings will aid in risk assessment and early prevention of complications for patients with severe trauma.

Ethanol-induced DNA damage and repair-related molecules in human intestinal epithelial Caco-2 cells

The acute administration of ethanol to intestinal epithelial cells causes increased intestinal permeability and the translocation of endotoxins. The changes caused by ethanol in intestinal cells may be related to oxidative stress and DNA damage. However, DNA damage and repair-related molecules which act against stresses, including ethanol, have not been fully investigated in intestinal cells. Heat shock proteins (Hsps) are involved in the recovery and protection from cell damage and may be associated with DNA repair. Therefore, the aim of our study was to investigate cytotoxicity, DNA damage and the expression of DNA repair-related molecules, antioxidant proteins and Hsps in intestinal cells exposed to ethanol. Human intestinal Caco-2 cells were incubated with 1-8% ethanol for 1 h. Cell viability and DNA damage were determined using the MTT and comet assays, respectively. We measured DNA repair-related molecules, including DNA polymerase β, apurinic/apyrimidinic endonuclease/redox factor-1 (APE/Ref-1), growth arrest and DNA damage 45α (GADD45α) and proliferating cell nuclear antigen (PCNA), in Caco-2 cells using western blot analysis. We also measured glutathione peroxidase-1 (GPx-1), peroxiredoxin-1 (PRX-1), superoxide dismutase-2 (SOD-2), Hsp10, Hsp27, Hsp60, heat shock cognate (Hsc)70, Hsp70 and Hsp90. The viability of the Caco-2 cells exposed to ethanol decreased at concentrations ≥ 7% (P<0.05). The Olive tail moment, indicating DNA damage, increased dose dependently in ≥ 3% ethanol (P<0.05). Among the DNA repair proteins, the expression of PCNA and APE/Ref-1 increased significantly at 1% ethanol. Antioxidant enzymes, including GPx-1, PRX-1 and SOD-2, had an increased expression at 1% ethanol. Hsp10, Hsp27 and Hsp70 expression also increased significantly at 1% ethanol. In conclusion, the expression of DNA repair molecules, antioxidants and Hsps increased in intestinal Caco-2 cells exposed to low concentrations of ethanol. In particular, PCNA, APE/Ref-1, Hsp10, Hsp27 and Hsp70 were sensitive to low ethanol concentrations, indicating that they may be useful in evaluating the DNA repair and cytoprotective effects of the drug against stress in intestinal cells.

The management of portal hypertensive gastropathy and gastric antral vascular ectasia

Portal hypertensive gastropathy and gastric antral vascular ectasia are gastric mucosal lesions that can cause chronic gastrointestinal haemorrhage and, consequently, chronic anaemia, in patients with cirrhosis. Although chronic anaemia is the most common clinical manifestation, these entities may also lead to acute gastrointestinal bleeding. Despite similar clinical manifestations, their pathophysiology and management are entirely different. Their diagnosis is endoscopic and although generally each of them has a characteristic endoscopic appearance and distribution, there are cases in which the differential is difficult and must rely on histology. This review focuses on the management of both entities. The mainstay of management of portal hypertensive gastropathy is based on portal-hypotensive pharmacological treatment whilst gastric antral vascular ectasia benefits from endoscopic therapy. More invasive options should be reserved for refractory cases.

Gastroduodenal mucosal defense

PURPOSE OF REVIEW

We have summarized recent findings related to gastroduodenal mucosal defense as well as factors contributing to defensive failure, highlighting findings that illuminate new pathophysiological mechanisms.

RECENT FINDINGS

Gastroduodenal bicarbonate secretion is mediated by prostaglandin E receptors and stimulated by the prostone lubiprostone. Toll-like receptor (TLR)4 signaling is protective against gastric injury. Intestinal alkaline phosphatase (IAP) is a chemosensor that regulates the duodenal mucosal surface pH. Lipopolysaccharide (LPS) increases gastric permeability; IAP secreted during fat digestion may detoxify colonic LPS. NADPH oxidase activity mediates ischemia/reperfusion-related gastric mucosal damage. Heat shock protein 70 (HSP70) protects the gastric mucosa through inhibition of apoptosis, proinflammatory cytokines, and cell adhesion molecules (CAMs). HSP90 may be a contributing factor in impaired adaptive cytoprotection. Proteinase-activated receptor-1 (PAR-1) is protective against Helicobacter-induced gastritis, mediated by the suppression of proinflammatory pathways. IKK β/NF-κB signaling decreases chronic Helicobacter-induced inflammation by inhibiting cellular apoptosis and necrosis. Activation of A2A adenosine receptors decreases inflammation and gastritis but leads to persistent Helicobacter pylori infection.

SUMMARY

Enhanced understanding of the mechanisms of gastroduodenal defense and injury provides new insight into potential therapeutic targets, contributing towards the development of better tolerated and more effective therapies.

Heat shock protein: hard worker or bad offender for gastric diseases

Heat shock proteins (HSPs) have core housekeeping functions in the cells where they are built-in components of folding, signal transduction pathways, and quality control functions for which they proofread the structure of proteins and repair misfolded conformers. Helicobacter pylori (H. pylori) infection leads to significant inflammations in the gastric mucosa, which is closely associated with development of either precancerous lesion including chronic atrophic gastritis or gastric cancer in addition to, peptic ulcer disease, and mucosa-associated lymphoid tissue (MALT) lymphoma. Therefore, the association between H. pylori infection and role of HSP has been focused as an important issue because there had been rather conflicting publications showing that HSPs as a good worker for defense against H. pylori infection, whereas HSPs as a bad offender contributing to the progression of H. pylori-associated gastric carcinogenesis in addition to aggravation of gastric inflammation. In this paper regarding proteomic discovery of HSPs related to H. pylori-associated gastric diseases, we introduce several evidences obtained from proteomic analysis dealing with friend or foe role of HSP in H. pylori infection from a cellular level to human diseases. The implication of HSPs in alcoholic or NSAIDs-induced gastritis and the intervening of HSPs in biological changes exemplified with TGF-β signaling, key tumor suppressor growth factors regulating inflammation, immune function, and carcinogenesis were further introduced.