Pan-genomic analysis of bovine monocyte-derived macrophage gene expression in response to in vitro infection with Mycobacterium avium subspecies paratuberculosis

Abstract

Mycobacterium avium subspecies paratuberculosis is the causative agent of Johne’s disease, an intestinal disease of ruminants with major economic consequences. Infectious bacilli are phagocytosed by host macrophages upon exposure where they persist, resulting in lengthy subclinical phases of infection that can lead to immunopathology and disease dissemination. Consequently, analysis of the macrophage transcriptome in response to M. avium subsp. paratuberculosis infection can provide valuable insights into the molecular mechanisms that underlie Johne’s disease. Here, we investigate pan-genomic gene expression in bovine monocyte-derived macrophages (MDM) purified from seven age-matched females, in response to in vitro infection with M. avium subsp. paratuberculosis (multiplicity of infection 2:1) at intervals of 2 hours, 6 hours and 24 hours post-infection (hpi). Differentially expressed genes were identified by comparing the transcriptomes of the infected MDM to the non-infected control MDM at each time point (adjusted P-value threshold ≤ 0.10). 1050 differentially expressed unique genes were identified 2 hpi, with 974 and 78 differentially expressed unique genes detected 6 and 24 hpi, respectively. Furthermore, in the infected MDM the number of upregulated genes exceeded the number of downregulated genes at each time point, with the fold-change in expression for the upregulated genes markedly higher than that for the downregulated genes. Inspection and systems biology analysis of the differentially expressed genes revealed an enrichment of genes involved in the inflammatory response, cell signalling pathways and apoptosis. The transcriptional changes associated with cellular signalling and the inflammatory response may reflect different immuno-modulatory mechanisms that underlie host-pathogen interactions during infection.

Whole-transcriptome, high-throughput RNA sequence analysis of the bovine macrophage response to Mycobacterium bovis infection in vitro

“…This assertion is supported in the current study by the increased dynamic range of RNA-seq compared to the microarray platform. In agreement with previous studies, however, the expression fold-change values were markedly higher for upregulated genes compared to downregulated genes [17,19-21]. …”

Comparative Functional Genomics and the Bovine Macrophage Response to Strains of the Mycobacterium Genus

“…All infected and control MDM used to generate these data were derived from the same seven age-matched Holstein-Friesian females, while a multiplicity of infection (MOI) of 2:1 (i.e., 2 bacilli:1 MDM) was used for all MDM infections (61, 62). Gene expression omnibus (GEO) data series accession numbers used for these re-analyses were GSE33309, GSE35185, and GSE59774 (66).…”

Anti-Inflammatory and Antiapoptotic Responses to Infection: A Common Denominator of Human and Bovine Macrophages Infected withMycobacterium aviumSubsp.paratuberculosis

“…By using a pan-genomic analysis of bovine MDM gene expression in response to in vitro infection with Map , Machugh et al revealed that many of the highly upregulated genes at 2 h p.i. had proinflammatory related functions, particularly IL-1 α , IL-1 β , TNF, IL-6, chemokine ligand 2 gene (C-X-C motif; CXCL2), and the chemokine ligand 20 gene (C-C motif; CCL20) [39]. At 6 h p.i.…”