Role of endoplasmic reticulum stress in liver and distant organ injury in liver ischemia reperfusion model

Aim: Liver ischemia / reperfusion injury, occurs in pringle maneuver requiring liver surgery and liver transplantation by transient ischemia, and after that re-establishment of circulation. Free oxygen radicals, which emerge during reperfusion, play an important role in ischemia / reperfusion injury. With the effects of these free radicals, unfolded or missfolded proteins in endoplasmic reticulum can trigger endoplasmic reticulum stress. Them aim of this study to understand role of endoplasmic reticulum stress in cell death and the presence of this stress in both liver and in distant organs such as lung, kidney, brain. Material and Method: Total 15 adult male Wistar Albino rats, weight between 180-300 gr, was used. Rats were randomized into 3 groups. Group 1: Ischemia / reperfusion: Rats were opened with midline incision and hepatic portal vein and the hepatic artery were closed with a bulldog clamp. At the end of 60 minutes ischemia period, 60 minutes of reperfusion was applied. At the end of reperfusion; rats were sacrified and their liver, lung, kidney and brain tissues were collected. Some of these tissues were stored for pathology in 10% formaldehyde and the remaining tissues were stored at -80 C in RNA later for RNA isolation. Group 2: Sham: rats were opened with midline incision and after waiting for 120 minutes they were sacrified and their liver, lung, kidney and brain tissues were collected for pathology and RNA isolation. Group 3: Control: No procedures were applied to this group, and again their liver, lung, kidney and brain tissues were collected for pathology and RNA isolation. Some of these collected tissues were taken into 10% formaldehyde for Immunohistochemical studies and the remaining parts were used for RNA isolation. RNAs were converted to cDNA and the expression levels of ER stress genes, GRP78, PERK, ATF6 and CHOP, were examined with lightcycler 480 device. Results were evaluated with student-t test p≤ 0.05 was accepted as statistically significant. Results: There was a slight increase in the expression levels of ER stress genes in liver, lung, kidney and brain when copared with sham group but this difference was not statistically significant. There was a statistically significant increase for the expression levels of ATF6, PERK and CHOP genes in liver and the expression level of CHOP gene in lung, kidney and brain. Moreover as a result of Immunohistochemical studies; there was parenchymal cell injury and neutrophil leukocytes infiltration which was characterized with narrowing of hepatocytes cords and hepatocellular loss in ischemia reperfusion group. Conclusion: After liver I/R injury; effect of ER stress was observed in distant organs such as lung, kidney and brain in addition to liver. As a result of this we understand that ER stress after I/R can effect both local and distant organs and this study will set light to further studies for reducing this stress.