Serum miR-30b is increased in Labrador Retrievers with elevated hepatic copper levels

Copper-associated hepatitis is a hereditary disease in Labrador Retrievers with a complex genetic background. Currently, liver biopsies are needed for diagnosis and treatment monitoring. A serum-based biomarker for hepatic copper levels could provide a less invasive diagnostic approach. Circulating microRNAs are increasingly studied for their diagnostic potential in hepatobiliary disease and could be utilized in assessing hepatic copper levels. Currently, information on the potential use of copper specific microRNAs in dogs is lacking. The aim of this pilot study was to identify microRNAs associated with elevated hepatic copper levels in Labrador Retrievers. Client-owned Labrador Retrievers with normal (n = 15) and elevated hepatic copper levels (n = 21) were retrospectively selected from a patient database. We performed a microRNA screening array of 277 microRNAs in blood serum of Labrador Retrievers with normal (n = 5) and elevated hepatic copper levels (n = 5). MicroRNAs upregulated in Labrador Retrievers with elevated hepatic copper were subsequently analyzed with qPCR in a replication cohort of Labrador Retrievers with normal (n = 13) and elevated (n = 18) hepatic copper levels. Results showed that six out of the 277 serum microRNAs were significantly upregulated in dogs with elevated hepatic copper and these were analyzed in the replication cohort. After Bonferroni correction, cfa-miR-30b (fold-change 2.17, p-value .002) was significantly upregulated in the replication cohort. In this exploratory study, cfa-miR-30b is increased in Labrador Retrievers with elevated hepatic copper levels. This result justifies validation in a larger cohort of dogs with and without hepatic copper accumulation, including those with different forms of liver disease and other breeds affected by copper-associated hepatitis.