Genome-wide whole blood microRNAome and transcriptome analyses reveal miRNA-mRNA regulated host response to foodborne pathogen Salmonella infection in swine.

To understand the role of miRNAs in regulating genes involved in host response to bacterial infection and shedding of foodborne pathogens, a systematic profiling of miRNAs and mRNAs from the whole blood of pigs upon Salmonella challenge was performed. A total of 62 miRNAs were differentially expressed post infection (false discovery rate <0.1). An integrative analysis of both the differentially expressed miRNAs and mRNAs using sequence-based miRNA target prediction and negative correlation of miRNA-mRNA profiles helped identify miRNA-mRNA networks that may potentially regulate host response to Salmonella infection. From these networks, miR-214 and miR-331-3p were identified as new candidates potentially associated with Salmonella infection. An miRNA seed sequence analysis suggested that these miRNAs regulate several critical immune-related genes including SLC11A1, PIGE-108A11.3 and VAV2. We showed that challenged pigs had reduced miR-214 expression and increased miR-331-3p expression in the whole blood. Furthermore, the expression of the proposed targets of miR-214 (SLC11A1 and PIGE-108A11.3) increased while that of the proposed target of miR-331-3p (VAV2) decreased following challenge (expression changes confirmed by in vitro assays). Based on these observations, we propose potential roles for miR-214 and miR-331-3p in regulation of immune responses to Salmonella infection.