Oral Presentation International Veterinary Immunology Symposium 2016

MiRNAseq of neutrophils during the transition period in cows with divergent metabolic phenotypes. (#75)

Mallory A Crookenden 1 , Caroline G Walker 1 , Axel Heiser 2 3 , Juan J Loor 4 , Kasey M Moyes 5 , Jane K Kay 6 , Susanne Meier 6 , Alan Murray 3 , Venkata SR Dukkipati 3 , Murray D Mitchell 7 , John R Roche 6
  1. DairyNZ, Auckland, N/A, New Zealand
  2. AgResearch, Massey University, Palmerston North, New Zealand
  3. IVABS, Massey University, Palmerston North, New Zealand
  4. Animal Sciences & Division of Nutritional Sciences, University of Illinois, Urbana, Illinois, USA
  5. Animal and Avian Sciences, University of Maryland, College Park, Maryland, USA
  6. DairyNZ, Hamilton, New Zealand
  7. UQCCR, University of Queensland, Brisbane, QLD, Australia

Several adaptations in leukocytes are required for a successful transition to lactation in dairy cows. Micro RNA (miRNA) molecules are small non-coding RNAs that regulate gene expression; their importance in immune cell function has been well documented. We characterized the miRNA of neutrophils isolated from dairy cows divergent in their risk of infection or metabolic dysfunction, at three time-points over the transition period: day of calving, 1 wk, and 4 wk post-calving. From a total of 150 cows, 10 cows were selected with high (n = 5; High Risk) and low (n = 5; Low Risk) concentrations of non-esterified fatty acids, β-hydroxybutyrate, and liver triacylglycerol during wk 1 and 2 post-calving. Neutrophils were isolated from whole blood and flow cytometric analysis of these isolates revealed a median of 75% ± 2% neutrophils (± SEM). Total RNA was extracted using TRIzol®, size selected for miRNA, and sequenced on the Illumina HiSeq. Pair-wise analyses were conducted to assess differential expression between risk categories and across time-points. There was no effect of risk category on miRNA expression on the day of calving or 4 wk post-calving. However, expression of mir-19b, mir-148a, and mir-21 in the Low Risk cows tended (P = 0.1) to be greater at 1 wk post-calving. When assessed for the effect of time relative to the day of calving, regardless of risk, expression of miR-150 and -486 increased (P ≤ 0.05) at 1 wk post-calving and at 4 wk post-calving (P ≤ 0.05) miR-150 and -30c, miR-19b, -19a, -30d, -101-1, and -106b were differentially expressed. The results indicate that the divergent metabolic phenotype did not significantly alter miRNA in neutrophils during early lactation. However, the altered miRNA profile in neutrophils over time indicates an important role for miRNA in the regulation of immune cell function during the peripartum period.