Sometimes many paths can lead to the same destination, and in the case of liver disease, it’s important for proper treatment to know the exact route that led to problems. New research shows that exosome miRNAs can tell scientists exactly how liver damage was caused.
Several things, from chemicals to viruses, can trigger liver damage and up to now that has been measured by biochemical markers that have a few limitations like needing fresh blood samples, no tissue specificity, and the biggest problem; that they can’t tell the difference between hepatocyte damage and inflammation.
Researchers from the University of Massachusetts thought that miRNAs circulating in exosomes may be a better guide to liver disease and so they focused their studies on four miRNAs associated with the liver: miRNA-122, miRNA-155, miRNA-125b and miRNA-146a. The UMass team hypothesized that circulating microRNAs could be markers of liver damage and/or inflammation and began testing circulating miR-122 as a potential marker of hepatocyte damage and miR-155 as an inflammation marker in liver injuries brought on by alcohol, acetaminophen or CpG+LPS exposure, with the following results:
- Circulating miR-122 and miR-155 increased in alcoholic liver disease (ALD) samples
- Acetaminophen treatment raised circulating miRNA-122, miR-155, miR-125b and miR-146a levels
- Samples with inflammation-induced liver injury had higher plasma miRNA-122, -155 and -146a.
- Depending on the type of liver damage, miRNAs localize to exosome-rich (alcohol or inflammation) or protein-rich (acetaminophen induced necrosis) serum fractions.
In total the authors show that stimuli-specific miR-122 and miR-155 signatures in both the liver and serum/plasma might make for good liver damage and inflammation biomarkers. The researcher also look forward to exploring what exactly is involved in the assembly of miRNAs into exosomes or protein compartments in liver injury.
Get the latest on miRNA liver biomarkers at Hepatology, June 2012.