Hepatic regeneration following radiation-induced liver injury is associated with increased hepatobiliary secretion measured by PET in Göttingen minipigs

Microarray analysis identifies coding and non-coding RNA markers of liver injury in whole body irradiated mice

Radiation injury from medical, accidental, or intentional sources can induce acute and long-term hepatic dysregulation, fibrosis, and cancer. This long-term hepatic dysregulation decreases quality of life and may lead to death. Our goal in this study is to determine acute changes in biological pathways and discover potential RNA biomarkers predictive of radiation injury. We performed whole transcriptome microarray analysis of mouse liver tissue (C57BL/6 J) 48 h after whole-body irradiation with 1, 2, 4, 8, and 12 Gray to identify significant expression changes in mRNAs, lncRNAs, and miRNAs, We also validated changes in specific RNAs through qRT-PCR. We used Ingenuity Pathway Analysis (IPA) to identify pathways associated with gene expression changes. We observed significant dysregulation of multiple mRNAs across all doses. In contrast, miRNA dysregulation was observed upwards of 2 Gray. The most significantly upregulated mRNAs function as tumor suppressors: Cdkn1a, Phlda3, and Eda2r. The most significantly downregulated mRNAs were involved in hemoglobin synthesis, inflammation, and mitochondrial function including multiple members of Hbb and Hba. The most significantly upregulated miRNA included: miR-34a-5p, miR-3102-5p, and miR-3960, while miR-342-3p, miR-142a-3p, and miR-223-3p were most significantly downregulated. IPA predicted activation of cell cycle checkpoint control pathways and inhibition of pathways relevant to inflammation and erythropoietin. Clarifying expression of mRNA, miRNA and lncRNA at a short time point (48 h) offers insight into potential biomarkers, including radiation markers shared across organs and animal models. This information, once validated in human models, can aid in development of bio-dosimetry biomarkers, and furthers our understanding of acute pathway dysregulation.

Amelioration of radiation-induced liver damage by p-coumaric acid in mice

Radiation-induced liver damage (RILD) is a spiny problem in radiotherapy or other circumstances that exposure to radiation. The need for radioprotective agent is increasing to protect liver tissue. This study aimed to explore the hepatoprotective effect of p-coumaric acid (CA) against RILD. C57BL/6 male mice were exposed to 4 Gy irradiation and administrated with CA for 4 days starting on the same day of irradiation. Mice were sacrificed to obtain blood and liver tissues on day 3.5 or 14 post irradiation, respectively. The blood and liver tissues were collected. As compared with the only irradiated group, CA supplementation improved liver morphology, decreased serum alanine aminotransferase and aspartate aminotransferase, inhibited BCL2-associated X (BAX) protein expression, and improved the mice hematopoietic function. CA at the dose of 100 mg/kg body weight showed better effect compared to the other doses. Thus, CA might possess potential to protect against RILD.

Hepatic blood flow in adult Göttingen minipigs and pre-pubertal Danish Landrace x Yorkshire pigs

The liver receives dual blood supply from the hepatic artery and portal vein. The pig is often used as an animal model in positron emission tomography (PET) and pharmacokinetic studies because of the possibility for extensive and direct blood sampling. In this study, we compared measurements of hepatic blood flow in 10 female adult Göttingen minipigs and 10 female pre-pubertal Danish Landrace x Yorkshire (DLY) pigs. Ultrasound transit time flow meter probes were placed around the hepatic artery and portal vein through open surgery, hepatic blood flow measurements were performed, and the liver was weighed. Total hepatic blood flow was on average 363 ± 131 mL blood/min in Göttingen minipigs and 988 ± 180 mL blood/min in DLY pigs (p < 0.001). The mean hepatic blood perfusion was 623 mL blood/min/mL liver tissue and 950 mL blood/min/mL liver tissue (p = 0.005), and the liver weight was 0.58 kg and 1.04 kg, respectively. The mean arterial flow fraction in Göttingen minipigs was 12 ± 7% and lower than in DLY pigs, where it was 24 ± 7% (p = 0.001). Using the gold standard for blood flow measurements, we found that both total hepatic blood flow and blood perfusion were significantly lower in Göttingen minipigs than in DLY pigs. The hepatic blood perfusion and arterial flow fraction in DLY pigs were comparable to normative values from humans. Differences in hepatic blood flow between adult Göttingen minipigs and humans should be considered when performing physiological liver studies in this model.

Gene Expression Profiles from Heart, Lung and Liver Samples of Total-Body-Irradiated Minipigs: Implications for Predicting Radiation-Induced Tissue Toxicity

In the event of a major accidental or intentional radiation exposure incident, the affected population could suffer from total- or partial-body exposures to ionizing radiation with acute exposure to organs that would produce life-threatening injury. Therefore, it is necessary to identify markers capable of predicting organ-specific damage so that appropriate directed or encompassing therapies can be applied. In the current work, gene expression changes in response to total-body irradiation (TBI) were identified in heart, lungs and liver tissue of Göttingen minipigs. Animals received 1.7, 1.9, 2.1 or 2.3 Gy TBI and were followed for 45 days. Organ samples were collected at the end of day 45 or sooner if the animal displayed morbidity necessitating euthanasia. Our findings indicate that different organs respond to TBI in a very specific and distinct manner. We also found that the liver was the most affected organ in terms of gene expression changes, and that lipid metabolic pathways were the most deregulated in the liver samples of non-survivors (survival time <45 days). We identified organ-specific gene expression signatures that accurately differentiated non-survivors from survivors and control animals, irrespective of dose and time postirradiation. At what point did these radiation-induced injury markers manifest and how this information could be used for applying intervention therapies are under investigation.