Different Blood Cell-Derived Transcriptome Signatures in Cows Exposed to Vaccination Pre- or Postpartum

Abstract

Periparturient cows have been found to reveal immunosuppression, frequently associated with increased susceptibility to uterine and mammary infections. To improve understanding of the causes and molecular regulatory mechanisms accounting for this phenomenon around calving, we examined the effect of an antigen challenge on gene expression modulation on cows prior to (BC) or after calving (AC) using whole transcriptome sequencing (RNAseq). The transcriptome analysis of the cows' blood identified a substantially higher number of loci affected in BC cows (2,235) in response to vaccination compared to AC cows (208) and revealed a divergent transcriptional profile specific for each group. In BC cows, a variety of loci involved in immune defense and cellular signaling processes were transcriptionally activated, whereas protein biosynthesis and posttranslational processes were tremendously impaired in response to vaccination. Furthermore, energy metabolism in the blood cells of BC cows was shifted from oxidative phosphorylation to the glycolytic system. In AC cows, the number and variety of regulated pathways involved in immunomodulation and maintenance of immnunocompetence are considerably lower after vaccination, and upregulation of arginine degradation was suggested as an immunosuppressive mechanism. Elevated transcript levels of erythrocyte-specific genes involved in gas exchange processes were a specific transcriptional signature in AC cows pointing to hematopoiesis activation. The divergent and substantially lower magnitude of transcriptional modulation in response to vaccination in AC cows provides evidence for a suppressed immune capacity of early lactating cows on the molecular level and demonstrates that an efficient immune response of cows is related to their physiological and metabolic status.

Fig 1. Cluster analysis of transcriptional response to vaccination across all cows included in the RNAseq experiment.

Red: non-lactating cows vaccinated prior to calving (BC), blue: early lactating cows vaccinated after calving (AC), green: mid- lactating cow, yellow: non-lactating cow of different genetic background, lavender: non-lactating first calving cow.

Fig 2. Number of differentially expressed loci in cows vaccinated prior to and after calving.

N: Number of differentially expressed transcripts, BC: Cows vaccinated prior to calving, non-lactating. AC: Cows vaccinated prior to calving, early lactating.

Fig 3. The most significant biological function categories (IPA) affected in cows vaccinated prior to and after calving.

Vaccination: Red, prior to calving (BC); green: after calving (AC).

Fig 4. Model of reciprocal regulation of arginase 1 (ARG1) and nitric oxide synthase 2 (NOS2).

Downstream metabolic products (blue framed) and their association with components of inflammatory responses (red). Enzymes (blue ellipses), NOHA: N-hydroxyarginine, OAT: ornithine aminotransferase, ODC: ornithine decarboxylase, ACL: argininosuccinate lyase, ASS: argininosuccinate synthetase. ROS: reactive oxygen species, RNOS: reactive nitrogen oxide species. Red arrows indicate consequences of ARG1 upregulation in AC cows vaccinated after calving.

Fig 5. Vaccination-induced upregulation of erythrocyte-specific genes involved in gas exchange in early lactating cows.

A: Interaction network for erythrocyte-enriched genes modulated in cows vaccinated after calving (AC) using IPA network analysis. Red: upregulated loci, green: downregulated loci. B: Model of the synergistic coactions of genes from the integrated gas exchange in the red blood cell. Genes (blue-framed boxes) upregulated in response to vaccination are indicated by red arrows. AQP1: aquaphorin, SLC4A1: band 3 anion exchange protein, CA2: carbonic anhydrase II, GYPB: glycophorin B, HBA, HBB: hemoglobin chains A and B, HBM: μ-globin, ALAS2: 5-aminolevulinate synthase 2, EPB42: erythrocyte membrane protein 4.2, ATPIF1: ATPase inhibitory factor 1, ACT: actin, TPM2: tropomyosin 2.

Fig 6. Interaction networks of modulated genes included in the electron transport chain in cows vaccinated prior to calving.

A: Downregulated genes included in the electron transport chain in cows vaccinated prior to calving (BC). Red: upregulated loci, green: downregulated loci. B: Interaction networks for loci in complex I in BC cows using IPA network analysis. C: Interaction networks for loci in complex III and IV in BC cows using IPA network analysis. Red: upregulated loci, green: downregulated loci.

Fig 7. Metabolic switch due to virus challenge in cows vaccinated prior to calving.

Loci (red-framed boxes) upregulated in response to vaccination are indicated by red arrows, loci (green-framed boxes) downregulated in response to vaccination are indicated by green arrows. CI-C V: complexes of the respiratory electron transport chain. PDK4: pyruvate dehydrogenase kinase 4, NNT: nicotinamide nucleotide transhydrogenase, CPT1A: carnitine palmitoyltransferase 1A, ACADM: acyl-CoA dehydrogenase, medium-chain, HK1: hexokinase 1, HIF1A: hypoxia inducible factor 1 alpha.