Altered patterns of toll-like receptor gene expression in cull cows infected with Mycobacterium avium subsp....

Area of Science:

• Veterinary Immunology
• Bovine Infectious Diseases
• Molecular Biology

Background:

• Johne's disease, caused by Mycobacterium avium subsp. paratuberculosis (MAP), is a chronic cattle enteric disease.
• The immune evasion mechanisms of MAP within the gastro-intestinal tract remain poorly understood.
• Toll-like receptors (TLRs) are crucial in innate and acquired immunity, but their specific roles in MAP infection are unclear.

Purpose of the Study:

• To investigate the expression and function of Toll-like receptors (TLRs) 1, 2, and 4 in cattle with Johne's disease.
• To determine how MAP influences TLR gene expression in immune cells and tissues.
• To explore potential polymorphisms in TLR genes associated with susceptibility to MAP infection.

Main Methods:

• Analysis of TLR1, TLR2, and TLR4 mRNA expression in mesenteric lymph node (MLN) cultures, peripheral blood mononuclear cells (PBMCs), and gut tissues from MAP-infected and control cattle.
• Stimulation of MLN and PBMC cultures with MAP antigens.
• Histopathological scoring and MAP culturing from gut tissues to classify infection severity.
• Screening for polymorphisms in TLR1, TLR2, and TLR4 genes.

Main Results:

• MAP antigen-specific TLR1 expression was significantly lower in infected cattle, indicating impaired TLR1 upregulation in response to MAP.
• TLR4 expression was significantly higher in MLN tissues of severely infected cattle, suggesting localized upregulation.
• Polymorphisms in TLR1 and TLR2 genes were detected in the studied cattle population.

Conclusions:

• Impaired recognition of MAP antigens by TLR1 may be a mechanism by which MAP evades the host immune system in infected cattle.
• Differential expression of TLR1 and TLR4 suggests complex immune responses to MAP infection.
• TLR gene polymorphisms warrant further investigation for their role in Johne's disease susceptibility.