Toll-like receptor, MHC II, B7 and cytokine expression by porcine monocytes and monocyte-derived dendritic cells in response to microbial pathogen-associated molecular patterns

Area of Science:

• Immunology
• Cell Biology
• Veterinary Science

Background:

• Pathogen-associated molecular patterns (PAMPs) are microbial molecules recognized by the innate immune system.
• Toll-like receptors (TLRs) are key pattern recognition receptors involved in PAMP detection.
• Monocytes and dendritic cells (DCs) are crucial immune cells that initiate adaptive immune responses.

Purpose of the Study:

• To investigate the effects of various PAMPs on porcine monocytes and monocyte-derived DCs (moDCs).
• To assess changes in toll-like receptor (TLR), MHC II, B7, and cytokine expression following PAMP treatment.
• To understand how these immune cells discriminate between microorganisms and bias immune responses.

Main Methods:

• Porcine monocytes and moDCs were treated with different PAMPs: LPS, CpG, lipoteichoic acid (LTA), poly IC, and peptidoglycan (Pep).
• Expression levels of TLRs (4, 5, 9), MHC II, B7, and cytokines (IL-4, IFN-gamma, IL-12p35, IL-10, IL-13) were analyzed.
• Quantitative real-time PCR was used to measure mRNA expression.

Main Results:

• PAMP treatment altered the expression of at least one TLR (4, 5, or 9) in monocytes and moDCs.
• MHC II and/or B7 expression was significantly up-regulated following PAMP treatment.
• LPS or LTA treatment tended to up-regulate TLR 4 and Th-1/Th-2 cytokines, while poly IC or CpG up-regulated TLR 9 and Th-1 cytokines. IL-4 mRNA was not detected.

Conclusions:

• Porcine monocytes and moDCs exhibit responses to microbial PAMPs similar to human and mouse counterparts.
• These cells alter TLR expression, up-regulate MHC II and B7, and modulate cytokine profiles towards Th-1 and/or Th-2 bias.
• Porcine monocytes and moDCs likely utilize TLRs to discriminate between microorganisms, influencing cytokine expression and immune response bias.