Short communication: Pegbovigrastim treatment in vivo does not affect granulocyte ability to migrate to endometrial cells and kill bacteria in vitro in healthy cows

摘要

In periparturient dairy cows, immune suppression,resulting in decreased neutrophil numbers and function,leads to increased susceptibility to postpartumconditions such as mastitis, retained placenta, and metritis.Administration of polyethylene glycol-conjugatedbovine granulocyte colony stimulating factor (pegbovigrastim,Imrestor; Elanco Animal Health, Greenfield,IN) 7 d before and within 24 h of calving, effectivelyimproves granulocyte production and function in vivoas well as in milk. A recently developed coculture assaywas adapted for use with endometrial epithelial cells toassess the effects of pegbovigrastim application on directedgranulocyte migration and bactericidal activityin vitro on a per-cell basis in endometrial cell cultures.Granulocytes from treated and untreated periparturientcows (6 and 5 per group, respectively) were evaluatedfor their ability to migrate to and kill bacteria aftertreatment, in context of the infected endometrium. Wehypothesized that in addition to increasing the absoluteconcentration of circulating neutrophil granulocytes,pegbovigrastim treatment in vivo alters the ability ofgranulocytes to migrate to endometrial cells in vitro.The results clearly show a marked increase in the totalconcentration of granulocytes and monocytes betweenthe 2 treatment groups as early as 2 d after the firstinjection, and this increased between the samples taken2 d after calving. No migratory or killing differenceswere identified between granulocytes of both groups,suggesting that pegbovigrastim-induced granulocyteswere as effective as non-induced cells. This may alsobe due to the absence of negative energy balance inthe study animals and leads us to conclude that thepositive effects seen in vivo are most likely based onthe larger number of granulocytes present rather thana direct effect of pegbovigrastim treatment on the functionalityof cells for the parameters tested in this study.