Ocular toxoplasmosis associated with up-regulation of miR-155-5p/miR-29c-3p and down-regulation of miR-21-5p/miR-125b-5p

Abstract Ocular toxoplasmosis (OT) is one of the most common manifestations of Toxoplasma gondii infection and can be related with congenital or acquired infections. OT cause posterior uveitis that cause serious sequelae as complete loss of vision. microRNAs (miRNAs) are small non-coding RNAs, which have regulatory roles in cells by silencing messenger RNA. This study evaluated gene expression of miR-155-5p, miR-146a-5p, miR-21-5p, miR-29c-3p and miR-125b-5p in plasma of 51 patients with ocular toxoplasmosis (OT Group), 26 individuals with asymptomatic toxoplasmosis (AT Group), and 25 healthy individuals seronegative for toxoplasmosis (NC Group). Peripherical blood samples were collected in tube with EDTA for plasma isolation, laboratorial diagnosis for toxoplasmosis and RNA extraction. miRNA expression of each sample was performed by qPCR and values were expressed in Relative Quantification (RQ). Results showed that miR-155-5p and miR-29c-3p were up-expressed in OT patients than AT individuals. On the other hand, miR-21-5p and miR-125b-5p were down-expressed in OT patients. Differences were statistically significant. miR-146a-5p expression was similar in OT patients and AT individuals, without significant difference. In addition, comparative analysis for miRNA levels between AT and OT groups confirms these results. So far, this is the first study to evaluate circulating miRNA levels in ocular toxoplasmosis. These findings may contribute to further studies evaluating the exact role of these miRNAs in the course of infection, which may help in understanding the complex parasite-host interaction and future use in diagnosis, prognosis and therapeutic control in ocular toxoplasmosis.