Area of Science:

• Immunology
• Veterinary Medicine
• Vaccinology

Background:

• Toll-like receptor (TLR) agonists are utilized as adjuvants to modulate immune responses in both animals and humans.
• Equine immunology research is crucial for developing effective disease prevention strategies.

Purpose of the Study:

• To evaluate the combined effects of TLR 4 agonist monophosphoryl lipid A (MPL) and TLR 3 agonist polyinosinic:polycytidylic acid (Poly I:C).
• To assess these effects on equine peripheral blood mononuclear cells (PBMCs), monocyte-derived dendritic cells (MoDCs), and bone marrow-derived mesenchymal stromal cells (BM-MSCs).

Main Methods:

• Equine PBMCs, MoDCs, and BM-MSCs were treated with MPL, Poly I:C, and their combination.
• mRNA expression of key immunomodulatory genes (IFN-γ, IL-1β, IL-4, IL-6, IL-8, IL-12p40, TNF-α, VEGF, MCP-1) was quantified using real-time polymerase chain reaction.

Main Results:

• The combination of MPL and Poly I:C significantly upregulated immunomodulatory responses in equine cells without cytotoxicity.
• Combined TLR agonist treatment induced greater mRNA expression of pro-inflammatory cytokines (IFN-γ, IL-6) in PBMCs compared to single agonists.
• The combination significantly increased mRNA expression of IL-1β, IL-6, IL-12p40 in MoDCs, and IL-8, MCP-1, VEGF in BM-MSCs.

Conclusions:

• The combination of MPL and Poly I:C demonstrates significant immunomodulatory effects on equine immune cells.
• This TLR agonist combination is a potential adjuvant candidate for equine vaccines to prevent infectious diseases.