Lipopolysaccharide-binding protein: Local expression in bovine extrahepatic tissues

Area of Science:

• Veterinary immunology
• Bovine molecular biology
• Host-pathogen interactions

Background:

• Lipopolysaccharide-binding protein (LBP) is an acute phase protein crucial for host defense against bacterial pathogens.
• LBP is primarily synthesized by hepatocytes and circulates in plasma, but its distribution in non-pathological bovine tissues is largely uncharacterized.

Purpose of the Study:

• To investigate the extrahepatic expression of LBP in various bovine tissues.
• To determine the localization and quantity of LBP mRNA and protein in key tissues, focusing on the digestive tract and mammary gland.

Main Methods:

• Qualitative and quantitative real-time PCR (RT-PCR) were employed to assess LBP mRNA expression.
• Immunohistochemistry was used to confirm the presence and localization of LBP protein, utilizing a cross-validated anti-human LBP antibody.

Main Results:

• Moderate LBP mRNA levels were detected across most investigated tissues.
• Significantly high LBP mRNA expression was observed in parotid and submandibular salivary glands, rumen, reticulum, omasum, and the mammary gland.
• Protein staining intensity generally correlated with mRNA expression, with notable exceptions in lung, ovary, and thyroid gland.

Conclusions:

• Extrahepatic LBP expression is widespread in bovine tissues, with notable concentrations in mucosal tissues like the digestive tract and mammary gland.
• The presence of LBP in bovine forestomachs suggests a potential role in local immune responses within these organs.
• LBP's distribution indicates a significant function in mucosal immunity, particularly at sites of direct bacterial exposure.