Serum haptoglobin–matrix metalloproteinase 9 (Hp–MMP 9) complex as a biomarker of systemic inflammation in cattle

A reliable and specific test that discriminates between acute neutrophil activation and chronic inflammatory disease may be useful in clinical decision making in a variety of conditions encountered in veterinary medical practice. An ELISA specific for neutrophil-derived haptoglobin–matrix metalloproteinase 9 (Hp–MMP 9) complexes was used to determine serum concentrations of Hp–MMP 9 and was compared to ELISA assays for Haptoglobin (Hp) and matrix metalloproteinase 9 (MMP 9) in 15 animals with acute sepsis, 10 animals with chronic inflammatory or metabolic disease and 10 healthy cows. Animal disease classifications were completed prior to the determination of serum concentrations of the 3 proteins. Duration of illness, disease process and lesions observed at necropsy were used to place animals into a specific classification. The serum MMP 9 concentrations in healthy cows differed significantly from those measured in sera of acutely septic and chronically ill animals. Serum haptoglobin concentrations in healthy cows were negligible when compared to animals with acute septic or chronic diseases. There was substantial overlap in MMP 9 and Hp concentrations between acute and chronic disease animals. In contrast, serum concentrations of Hp–MMP 9 complexes found almost exclusively in sera from acutely septic animals but not in chronically ill and normal cattle. The Hp–MMP 9 ELISA may be the serological test of choice in the determination of systemic inflammation associated with bacterial sepsis.