Evaluation of circulating microRNAs in plasma from horses with non-strangulating intestinal infarction and idiopathic peritonitis.

Non-strangulating intestinal infarctions (NSII) associated with Strongylus vulgaris infection and idiopathic peritonitis (IP) share similar clinical presentation but require different treatment approaches. Horses with NSII need surgical intervention, while idiopathic peritonitis cases can be successfully treated with antimicrobials. A correct diagnosis is thus crucial, but because the two diseases overlap in clinicopathological features, differentiation is difficult in clinical practice. MicroRNAs (miRNAs) are non-coding RNAs that exhibit measurable changes in abundance in tissues and circulation during disease. This study aimed to explore differences in plasma miRNA abundance between patients with NSII and IP. Plasma samples were collected from 43 horses, consisting of 21 with NSII and 22 with IP. A subset (n = 12) was submitted for deep small RNA sequencing to identify miRNAs differing between the groups. Next, a panel of nine miRNAs (two were potential normalizers) were selected for evaluation and confirmation by reverse transcription quantitative real-time PCR (RT-qPCR). Small RNA sequencing detected 628 miRNAs in the blood samples, but no miRNAs were differentially abundant between the disease groups. This finding was confirmed by qPCR. In agreement with previous studies, the top abundant miRNAs in both groups included Eca-Mir-122-5p and Eca-Mir-486-5p, as well as Eca-Mir-223-3p, which has previously been associated with inflammation. Target prediction for the most abundant miRNAs additionally predicted targets in inflammatory pathways. Evaluation of clinicopathological parameters revealed differences between the groups in two measures (white blood cell count and blood neutrophil count), which aligns with findings from previous studies. The results demonstrate that NSII and IP elicit similar miRNA profiles in plasma and are characterized by systemic inflammation.