Study on the Regulatory Mechanism of oar-miR-29b in Lamb Encephalitis Caused by Enterococcus faecalis Infection

Enterococcus faecalis is an opportunistic pathogen that is capable of causing bacterial encephalitis under specific pathological conditions. MicroRNAs (miRNAs) are a class of small, single-stranded non-coding RNAs, typically approximately 21 nucleotides in length. As master regulators of gene expression, they orchestrate critical pathways across diverse organisms and a broad spectrum of diseases; however, their role during E. faecalis neuro-invasion remains unexplored.

A lamb model of E. faecalis-induced encephalitis was established. Integrated analysis of high-throughput sequencing data identified oar-miR-29b as a key differentially expressed miRNA during infection. To first verify its association with inflammation, primary SBMECs were stimulated with lipoteichoic acid (LTA), confirming that oar-miR-29b expression was significantly upregulated under inflammatory conditions. Subsequently, independent gain- and loss-of-function experiments in SBMECs were performed, with inflammatory cytokine expression assessed by qPCR and tight-junction protein levels evaluated by Western blotting.

Functional studies demonstrated that oar-miR-29b acts as a pro-inflammatory mediator, significantly upregulating IL-1β, IL-6, and TNF-α while degrading tight-junction proteins (ZO-1, occludin, and claudin-5), thereby compromising endothelial barrier integrity. Mechanistically, bioinformatic prediction and dual-luciferase reporter assays confirmed C1QTNF6 as a direct target of oar-miR-29b. The oar-miR-29b/C1QTNF6 axis is thus defined as a novel regulatory pathway contributing to neuro-inflammation and blood-brain barrier disruption.

Collectively, our findings identify the oar-miR-29b/C1QTNF6 axis as a novel pathogenic mechanism that exacerbates E. faecalis-induced neuroinflammation and blood-brain barrier disruption.