Pegbovigrastim treatment affects gene expression in neutrophils of pasture-fed,periparturient cows

Treatment with granulocyte colony-stimulating factor has been reported to increase circulating neutrophil count and enhance neutrophil function in the periparturient cow. It was hypothesized that a commercially available recombinant bovine granulocyte colony-stimulating factor product (pegbovigrastim) affects gene expression profiles of neutrophils and supports neutrophil function in periparturient cows. Hence this study was undertaken to analyze expression of genes involved in neutrophil functions, including migration, interaction with pathogens, and cell survival. It also assessed the hypothesis that gene expression profiles in neutrophils are modulated by negative energy balance in the peripartum period. Holstein-Friesian, Jersey, and mixed-breed cows on pasture were blocked by expected calving date and body condition score and randomly assigned in a 2 × 2 factorial design. Cows were fed to exceed energy requirements prepartum (122%) or restricted to approximately 85% of prepartum energy requirements. At approximately 7 d before expected calving date, half the cows in each feed group were randomly assigned to be injected with pegbovigrastim or saline. Treatments were repeated within 24 h after calving. Blood samples were collected pretreatment approximately 7 d before calving (d −7). Blood, uterine flush, and milk samples were collected at 4 (d 4) and 7 d in milk (d 7) to measure the expression of a panel of 20 genes representing cell adhesion, pattern recognition, inflammation and cytokine response, antimicrobial capacity, and apoptosis functions in neutrophils using NanoString technology (NanoString Technologies Inc., Seattle, WA) to quantify RNA copy numbers. No effects were observed of prepartum feeding group or a feeding group × treatment interaction for any of the investigated genes. An effect was observed of time on expression of several genes in blood neutrophils. After calving, expression of 2 of 4 cell adhesion-related genes, 3 of 4 pattern recognition receptors, 2 of 4 inflammatory genes, 2 antimicrobial genes, and 2 of 4 cell survival genes was significantly greater at d 4 or 7 or both compared with before calving (d −7). Expression of ICAM1, TLR2, and PTGS2 was significantly higher in blood neutrophils from animals treated with pegbovigrastim compared with untreated controls, suggesting greater migration, pattern recognition, and inflammatory response ability. Pegbovigrastim also affected RNA expression in uterine cells with ICAM1, NOD1, CLEC6A, PTGS2, MPO, DEFB5, and CATHL6 being expressed at higher levels and SELL, ITGB8, IL8RB, and IL10 at lower levels. Milk somatic cells showed a similar pattern but with fewer significant changes. In contrast to the reported decline in neutrophil function in the transition period, neutrophil gene expression was increased for many of the genes studied, an apparent attempt to compensate for reduced neutrophil function. Treatment with pegbovigrastim further increased expression of several genes involved in these processes in blood neutrophils and changed uterine cells to a phenotype with increased antimicrobial capacity, typical for neutrophils that have migrated into their target tissue.