Acute Phase Proteins: How they portray Mastitis – A review

Abstract

Acute Phase Proteins are blood proteins primarily synthesized by hepatocytes as part of the acute phase response (APR). APR to disease is accompanied by an increase in the circulating concentration of a number of plasma proteins which are collectively known as the Acute Phase Proteins. According to the concentration, APPs are classified in positive APP, if they increase or negative APP, if they decrease. During mastitis, APPs move from the systemic circulation to mammary gland or there could be de-novo synthesis of the APP within mammary gland tissues. Among the APPs, Serum Amyloid A (SAA), Haptoglobin (Hp), Alpha 1-acid glycoprotein and Lipopolysaccharide binding protein play a major role during mastitis in cattle and their concentration will increase with the severity of the infection, inflammation or trauma. SAA is involved in defense against Gram positive and Gram negative pathogens. SAA acts by modulating innate immune system and by acting as an opsonin. Among the SAA isoforms, mammary associated SAA3 (m-SAA3) is important. The blood concentration of SAA and Hp increases dramatically after LPS infusion, with SAA (acute and middle phase of APR) appearing before Hp (Late phase of APR). The herd level APP might be useful for determining the prevalence of clinical and subclinical infections indicated by the high serum concentration of selected APP and by serving as the prognostic tool. APPs, used as markers of animal health may possibly be influenced by environmental factors, handling procedures and other types of stress in the absence of disease.