Innate immune proteins as biomarkers for mastitis and endometritis

Subclinical infections of the mammary gland and reproductive tract of dairy cattle cause significant production losses through decreased milk yield and lowered fertility. in the absence of overt signs of infection, there are no simple, reliable, diagnostic tools to accurately identify cows with these conditions, some of which may progress to a clinical stage at a later date. A search was undertaken to identify proteins in milk and reproductive tract secretions that could serve as the basis for a biomarker-based diagnostic test. A 2d gel-based proteomic analysis of milk and of uterine secretions revealed a number of proteins whose abundance was altered with mastitis or endometritis. Western blotting and eliSA indicated that the levels of two of these proteins, the cathelicidins and S100A12 were increased 25 ± 3 fold, and 29 ± 6 fold, respectively, in milk from 8 cows with clinical mastitis, compared with milk from uninfected quarters. The levels of these proteins correlated strongly with somatic cell count in the milk (r=0.85 and 0.93 for cathelicidin and S100A12, respectively). changes in milk lactoferrin were less dramatic (7.9 ± 0.2 fold). in the uterine secretions, cathelicidins and S100A9 were increased (2 and 3-fold, P> 0.001; respectively) in secretions from cows with uterine infections, as assessed by uterine cytology, and were correlated (r = 0.87 and 0.64, respectively) with the percent of neutrophils in uterine cytological samples. cathelicidins and S100 proteins may have value as a basis for screening cattle for mucosal infections.