Hepatic Overexpression of GRP94 in a Rabbit Model of Parenteral Nutrition-Associated Liver Disease. Gastroenterol Res Pract. 2015;2015:269831. [PMID: 25918521 DOI: 10.1155/2015/269831]

Histopathological and ultra-structural investigation of the damaging effects of hypoinsulinemia, hyper glycaemia and oxidative stress caused by parenteral nutrition combined with fasting on the small intestine of rabbits

BACKGROUND AND STUDY AIMS

Parenteral nutrition (PN) is a life-saving practice when the use of the gastrointestinal tract is not appropriate. Despite its great benefits, however, PN may cause several complications. In this study, we conducted histopathological and ultra-structural examinations of the effect of PN combined with starvation on the small intestines of rabbits.

MATERIALS AND METHODS

Rabbits were divided into four groups. A fasting + PN group was left completely unfed and received all its daily required energy by PN through an intravenous central catheter. An oral feeding + PN group received half the necessary daily calories by oral feeding and the other half through PN. A semi-starvation group received only half the necessary daily calories by oral feeding and no PN. The fourth group, serving as a control, was supplied with its entire daily energy requirements through oral feeding. After 10 days, the rabbits were euthanized. Blood and small intestine tissue samples were collected from all groups. Blood samples were biochemically analysed, and tissue samples were examined by light and transmission electron microscopy.

RESULTS

The fasting + PN group exhibited lower insulin levels, higher glucose levels, and increased systemic oxidative stress than the other groups. Ultra-structural and histopathological examinations revealed a significant increase in apoptotic activity in this group's small intestines and a significant decrease in villus length and crypt depth. Severe damage to the intracellular organelles and nuclei of enterocytes was also observed.

CONCLUSION

PN combined with starvation appears to cause apoptosis in the small intestine due to oxidative stress and hyperglycaemia with hypoinsulinemia, with destructive effects on small intestine tissue. Adding enteral nutrition to PN may reduce these destructive effects.

Histopathologic and electron microscopic investigation of the damage to liver tissue caused by parenteral nutrition combined with starvation in rabbits

AIM OF THE STUDY

To conduct a histopathological examination of the damaging effects of the combination of parenteral nutrition (PN) with starvation on liver tissue using transmission electron and light microscopy.

MATERIAL AND METHODS

Four groups (n = 14 each) consisting of equal numbers of female and male New Zealand rabbits were formed: a group left completely unfed and receiving full-dose PN (full-dose PN group), a group provided with feed covering half its nutritional needs and receiving half-dose PN (half-dose PN + oral nutrition group), a group provided with feed covering half its nutritional needs (semi-starvation group), and a group provided with feed covering all its nutritional needs (control group). After 10 days, all rabbits were weighed, anesthetized, and euthanized, and liver tissue samples were collected. Histopathologic examination was performed by a surgical pathologist blinded to the experimental groups. Portal inflammation, ballooning degeneration, apoptosis and fibrosis were evaluated and statistically analyzed.

RESULTS

Severe portal inflammation, moderate portal fibrosis, slight ballooning degeneration, and moderate apoptosis were found in the full-dose PN group. Mild portal inflammation, fibrosis and mild apoptosis were found in the half-dose PN + oral nutrition group. The results of the other two groups were found normal.

CONCLUSIONS

Liver damage caused by PN combined with starvation can be devastating. The damage can be minimized by combining PN with enteral nutrition.

Investigation of the cardiotoxic effects of parenteral nutrition in rabbits

INTRODUCTION

Parenteral nutrition (PN) is used for the intravenous delivery of nutrients to patients who cannot take food orally. However, it is not clear whether PN also negatively impacts cardiac tissue. The present empirical study investigated the cardiac effects of PN in rabbits.

METHODS

The effects of PN were examined in three groups of rabbits: animals in the PN + fasting group (n = 14) had been fully fasted before receiving a full PN dose via an intravenous central catheter; the PN + oral feeding group (n = 14) received half of the daily calorie requirement as a half dose of PN via an intravenous central catheter; the third group consisted of controls (n = 14) with full enteral feeding and full enteral fluid intake with no PN and no central venous catheter. At the end of the 10-day study period, the rabbits were subjected to echocardiographic examination and euthanized. Blood and tissue samples were obtained from all groups. DNA was isolated from nucleated blood cells. Tissue samples were examined by both light and electron microscopy, relative telomere length was determined from DNA, and blood samples were analyzed biochemically.

RESULTS

At the end of the study, there were no statistically significant differences in weight change between the three groups. Echocardiography revealed minimally impaired diastolic function in the PN + fasting group compared to the other groups. Biochemical and histopathological analyses, relative telomere length determination, and electron micrographs showed significant cardiac damage in the PN + fasting group but not in the PN + oral feeding group or the control group. The blood biochemical analyses showed hyperglycemia and a low insulin level in the PN + fasting group but not in the other two groups.

CONCLUSIONS

A combination of PN and fasting may damage the cardiac muscle cells of rabbits via a mechanism involving hyperglycemia and oxidative stress. Additional enteral feeding may protect against the destructive effects of PN on cardiac tissue.

Suppression of IRE1α Attenuated the Fatty Degeneration in Parenteral Nutrition-Related Liver Disease (PNALD) Cell Model

Aims

To model the parenteral nutrition-associated liver disease (PNALD) in rat normal hepatocytes BRL and investigate the role of endoplasmic reticulum stress- (ERS-) related IRE1α signal in the process of PNALD.

Methods

The BRL cells were treated with different concentrations of soybean oil emulsion (SO) to induce hepatocyte fatty degeneration. The PNALD cell disease model was further confirmed by analysis of Oil Red O staining and biochemical parameters. Next, the IRE1α signal in the process of PNALD. α signal in the process of PNALD. α signal in the process of PNALD. α signal in the process of PNALD.

Results

The results of Oil Red O staining indicated that the PNALD was successfully established in BRL cells and the CCK-8 data indicated which 0.6% that SO was further applied to the experiment owing to its better induction of PNALD and less toxicity to the cells. Besides, the value of biochemical parameters (TBIL, DBIL, ALT, and AST) was also elevated in the SO group compared with the NG group. After knockdown of IRE1α signal in the process of PNALD. α signal in the process of PNALD.

Conclusion

IRE1α was induced in PNALD cell model and suppression of IRE1α resulted in reduced steatosis in this cell disease model. Taken together, our data suggested that the IRE1α pathway may be involved in the development of PNALD.α signal in the process of PNALD. α signal in the process of PNALD. α signal in the process of PNALD.

Polystyrene Nanoparticles Reduced ROS and Inhibited Ferroptosis by Triggering Lysosome Stress and TFEB Nucleus Translocation in a Size-Dependent Manner

Though plastic nanoparticles have already raised much concern for their potential impact on health, our understanding of their biological effects is still utterly limited. Here we demonstrate for the first time that carboxyl-modified polystyrene nanoparticles (CPS) could effectively inhibit ferroptosis as a result of reduced cellular ROS which was triggered by transcription factor EB (TFEB) nucleus translocation. In this process, CPS first entered cells via macropinocytosis, then CPS-containing macropinosomes fused with lysosomes and expanded into abnormal lysosome-like large vacuoles in vacuolar-type H⁺-ATPase (V-ATPase) and aquaporins (AQPs) in a dependent way. These large vacuoles were detected both in vitro and in vivo, which was found to be a sign of lysosome stress. The lysosome stress induced deactivation of mammalian target of rapamycin (mTOR) which led to nucleus translocation of TFEB. Then, TFEB-dependent enhanced expression of lysosomal proteins and superoxide dismutase (SOD) which ultimately led to ROS reduction and inhibition of ferroptosis. Knockout of TFEB-enhanced ferroptosis was triggered by Erastin and abolished the effect of CPS on ROS and ferroptosis. In summary, our results reveal a novel mechanism whereby CPS reduced ROS and inhibited ferroptosis in a TFEB-dependent way. These findings have important implications for understanding the biological effects of polystyrene nanoparticles and searching for new anti-ROS and antiferroptosis particles or reagents.

Activation of Caspase12, a key molecule in endoplasmic reticulum stress related apoptosis pathway, induces apoptosis of hepatocytes in rats with hepatic fibrosis

AIM: To observe the change of activity of Caspase12, a key signaling molecule in endoplasmic reticulum stress related apoptosis pathway, and to explore its role in the apoptosis of hepatocytes in rats with hepatic fibrosis.

METHODS: Wistar rats were randomly divided into a 4 wk control group, an 8 wk control group, a 4 wk hepatic fibrosis group and an 8 wk hepatic fibrosis group. Rats of hepatic fibrosis groups received subcutaneous injections of 40% CCl₄ twice a week at doses of 0.3 mL/100 g. Expression of GRP78, GRP94 and Caspase12 genes in hepatic tissue was detected by RT-PCR. The expression of GRP78, GRP94, procaspase12 and activated Caspase12 proteins was determined by Western blot. The apoptosis of hepatocytes was evaluated by TUNEL assay.

RESULTS: Expression of GRP78, GRP94 and Caspase12 mRNAs in the 4 wk hepatic fibrosis group was significantly higher than that in the 4 wk control group. In the 8 wk hepatic fibrosis group, expression of GRP78, GRP94 and Caspase12 mRNAs was also elevated obviously. Western blot analysis revealed that expression of GRP78, GRP94, procaspase12 and activated Caspase12 proteins was increased obviously in the liver in the 4 wk hepatic group. Compared with the 8 wk control group, expression of GRP78, GRP94, procaspase12 and activated Caspase12 proteins was elevated obviously in the 8 wk hepatic group. The apoptosis of hepatocytes in the 4 wk and 8 wk hepatic fibrosis groups was significantly higher than that in the control groups.

CONCLUSION: Activation of Caspase12, a key signaling molecule in endoplasmic reticulum stress related apoptosis pathway, may mediate the apoptosis of hepatocytes in rats with hepatic fibrosis.