Serum microRNAs-217 and -375 as biomarkers of acute pancreatic injury in rats.

Pancreatic injury in rats is primarily detected through histopathological changes and conventional serum biomarkers such as amylase and lipase. However, amylase and lipase have a short half-life and are markers of acinar, not islet cell injury. We investigated whether circulating microRNA (miR) levels that are enriched in acinar cells (miR-217, miR-216a/b) or islet cells (miR-375) could serve as markers of pancreatic injury. Rats were treated with a single dose of either vehicle, streptozotocin (STZ), caerulein, or acetaminophen (APAP), and necropsied at 4, 24, and 48h. Pancreas, liver, heart, kidney and skeletal muscle were analyzed for histopathology. Blood was collected at necropsy and processed to serum for amylase/lipase enzymatic determinations and miR qPCR analysis. Caerulein induced degeneration/necrosis of acinar cells at 4h that persisted for 48h. Caerulein-induced injury was associated with increases in serum amylase/lipase (4h), miR-216a/b (4, 24h). In contrast, serum miR-217 was detected at all time points examined. STZ did not induce increases in either amylase or lipase but did induce increases in miR-375 levels at 4 and 24h. No increases in miR-375 were observed in caerulein-treated rats, and no increases were observed in miR-217 and miR-216a/b in STZ-treated rats. APAP induced centrilobular necrosis in the liver 24h after treatment, but did not induce pancreatic injury or increases in miR-217 or miR-375. Our results suggest that miR-217 and miR-375 represent promising biomarkers of pancreatic injury in rats.

Evaluation of microRNAs-208 and 133a/b as differential biomarkers of acute cardiac and skeletal muscle toxicity in rats.

Conventional circulating biomarkers of cardiac and skeletal muscle (SKM) toxicity lack specificity and/or have a short half-life. MicroRNAs (miRNAs) are currently being assessed as biomarkers of tissue injury based on their long half-life in blood and selective expression in certain tissues. To assess the utility of miRNAs as biomarkers of cardiac and SKM injury, male Sprague-Dawley rats received a single dose of isoproterenol (ISO); metaproterenol (MET); allylamine (AAM); mitoxantrone (MIT); acetaminophen (APAP) or vehicle. Blood and tissues were collected from rats in each group at 4, 24 and 48h. ISO, MET, and AAM induced cardiac and SKM lesions and APAP induced liver specific lesions. There was no evidence of tissue injury with MIT by histopathology. Serum levels of candidate miRNAs were compared to conventional serum biomarkers of SKM/cardiac toxicity. Increases in heart specific miR-208 only occurred in rats with cardiac lesions alone and were increased for a longer duration than cardiac troponin and FABP3 (cardiac biomarkers). ISO, MET and AAM induced increases in MyL3 and skeletal muscle troponin (sTnl) (SKM biomarkers). MIT induced large increases in sTnl indicative of SKM toxicity, but sTnl levels were also increased in APAP-treated rats that lacked SKM toxicity. Serum levels of miR-133a/b (enriched in cardiac and SKM) increased following ISO, MET, AAM and MIT treatments but were absent in APAP-treated rats. Our results suggest that miR-133a/b are sensitive and specific markers of SKM and cardiac toxicity and that miR-208 used in combination with miR-133a/b can be used to differentiate cardiac from SKM toxicity.