Introduction: In recent years, the high sensitivity and specificity of novel miRNA biomarkers have been utilised for early diagnosis and treatment monitoring of various diseases. Previous reports showed that abnormal expression of miR-208 in mice resulted in the development of an aberrant cardiac conduction system and consecutive arrhythmias. On the other hand, a study on infarcted human heart tissue showed upregulation of miR-208a in subjects with ventricular tachyarrhythmias compared to healthy controls. We prospectively investigated the expression of miR-208a and -208b in the serum of dogs presenting different cardiac arrhythmias.
Material and Methods: A total of 28 dogs with atrial fibrillation (n = 8), ventricular premature contractions (n=6), conduction system disturbances (n = 7), and free of heart conditions (as controls) (n = 7) were enrolled in the study. Total RNA was extracted from serum samples and miR-208a and -b, miR-16 as well as a cel-miR-39-5p spike-in were analysed with qPCR and ddPCR.
Results: miR-208a and miR-208b were not expressed in any of the samples. The calculated ddPCR miR-16 relative expression (normalised with cel-miR-39 spike-in) showed a good correlation (r = 0.82; P < 0.001) with the qPCR results.
Conclusion: This outcome warrants further investigation, possibly focusing on tissue expression of miR-208 in the canine heart.
2. Bostjancic E., Zidar N., Stajer D., Glavac D.: MicroRNAs miR-1, miR-133a, miR-133b, and miR-208 are dysregulated in human myocardial infarction. Cardiology 2010, 115, 163–169.
3. Callis T.E., Pandya K., Seok H.Y., Tang R.H., Tatsuguchi M., Huang Z.P., Chen J.F., Deng Z., Gunn B., Shumate J., Willis M.S., Selzman C.H., Wang D.Z.: MicroRNA-208a is a regulator of cardiac hypertrophy and conduction in mice. J Clin Invest 2009, 119, 2772–2786.
4. Hindson C.M., Chevillet J.R., Briggs H.A., Gallichotte E.N., Ruf I.K., Hindson B.J., Vessella R.L., Tewari M.: Absolute quantification by droplet digital PCR versus analog real-time PCR. Nat Methods 2013, 10, 1003–1005.
5. Hulanicka M., Garncarz M., Parzeniecka-Jaworska M., Jank M.: Plasma miRNAs as potential biomarkers of chronic degenerative valvular disease in Dachshunds. BMC Vet Res 2014, 10, 205.
6. Kondkar A.A., Abu-Amero K.K.: Utility of circulating microRNAs as clinical biomarkers for cardiovascular diseases. Biomed Res Int 2015, 2015, 821–823.
7. Mestdagh P., Van Vlierberghe P., De Weer A., Muth D., Westermann F., Speleman F., Vandesompele J.: A novel and universal method for microRNA RT-qPCR data normalization. Genome Biology 2009, 10, R64.
8. Mitchell P.S., Parkin R.K., Kroh E.M., Fritz B.R., Wyman S.K., Pogosova-Agadjanyan E.L., Peterson A., Noteboom J., O’Briant K.C., Allen A., Lin D.W., Urban N., Drescher C.W., Knudsen B.S., Stirewalt D.L., Gentleman R., Vessella R.L., Nelson P.S., Martin D.B., Tewari M.: Circulating microRNAs as stable blood-based markers for cancer detection. Proc Natl Acad Sci USA 2008, 105, 10513–10518.
9. Noszczyk-Nowak A., McAulay G., Fuglewicz A., Nowak K., Janiszewski A., Skrzypczak P., Michałek M., Cepiel A., Pasławska U.: Radiofrequency catheter ablation of concealed accessory pathway of the heart in Labrador Retriever. Med Weter 2017, 73, 505–509.
10. Noszczyk-Nowak A., Michałek M., Kałuża E., Cepiel A., Pasławska U. Prevalence of arrhythmias in dogs examined between 2008 and 2014. J Vet Res 2017, 61, 103–110.
11. Schwarzenbach H., da Silva A.M., Calin G., Pantel K.: Data normalization strategies for microRNA quantification. Clin Chem 2015, 61, 1333–1342.
12. Song J., Bai Z., Han W., Zhang J., Meng H., Bi J., Ma X., Han S., Zhang Z.: Identification of suitable reference genes for qPCR analysis of serum microRNA in gastric cancer patients. Dig Dis Sci 2012, 57, 897–904.
13. Steudemann C., Bauersachs S., Weber K., Wess G.: Detection and comparison of microRNA expression in the serum of Doberman Pinschers with dilated cardiomyopathy and healthy controls. BMC Vet Res 2013, 9, 12.
14. Turchinovich A., Weiz L., Langheinz A., Burwinkel B.: Characterization of extracellular circulating microRNA. Nucleic Acids Res 2011, 39, 7223–7233.