The Functional Effects of Bovine CXCL8 Polymorphisms and Association to Inflammatory Disease: Mastitis As a Model

The chemokine CXCL8 plays a vital role in the innate immune response, recruiting neutrophils to the site of infection and activating neutrophil degranulation and phagocytosis. Single nucleotide polymorphisms (SNPs) in CXCL8 may affect expression and therefore influence the innate immune response during inflammation. CXCL8 has been well characterised in humans and SNPs have been associated with susceptibility to disease. The aim of this study was to identify SNPs and their functional effects in bovine CXCL8 in dairy cattle, and to analyse association with inflammatory disease using mastitis as a model.

A total of 30 SNPs were identified, and in silico analysis identified a SNP located in a putative transcription factor enhancer, in group 3 cows. Gene, but not protein, expression was maximally up-regulated in these cows (19% of the herd). Group 3 cows were also associated with the highest mastitis rate and the highest somatic cell count, but not the largest milk or protein yield. The results suggest that the mechanism for disease susceptibility may occur through genotypically determined modulation of CXCL8 transcription. These findings have the potential to impact upon the success of treatment, vaccine strategies and the improvement of livestock selective breeding programmes for disease control.