Induction and characterization of endotoxin tolerance in equine peripheral blood mononuclear cells in vitro.

This research aims to develop a method to induce ‘endotoxin tolerance’ in the immune cells of horses and examine its associated cytokine responses. The findings show that after repeated exposure to endotoxins, these cells developed a tolerance, leading to a significant decrease in the production of a specific cytokine, IL-12.

Objective of the Study

• The primary aim of the study was to generate a reliable method for triggering endotoxin tolerance (ET) in the Peripheral Blood Mononuclear Cells (PBMC) of horses using in vitro conditions. This was sought to better understand the development of unresponsiveness to recurrent endotoxin exposures observed in horses.
• The study further aimed to investigate the cytokine response associated with the development of ET, particularly focusing on the role and function of IL-10 and IL-12. These are important immune mediators and understanding their behavior in ET can improve understanding of equine immune responses.

Methodology

• The researchers used different concentrations of endotoxin to culture equine PBMC cells. Step 1 involved the initial exposure to the endotoxin, and in Step 2, the cells were given a second dose of endotoxin to observe the response.
• The relative mRNA expression of IL-10 and IL-12 was measured using quantitative Polymerase Chain Reaction (PCR). This helped in identifying the changes in the expression of these specific cytokines after endotoxin stimulation.

Results and Conclusion

• The findings of the experiment confirmed the induction of ET in all cells that were subjected to the two-step endotoxin challenge.
• Regarding cytokine responses, there was no change observed in the relative mRNA expression of IL-10 in the cells that developed tolerance. This indicates that IL-10 does not appear to have a significant role in the induction of ET in horse PBMCs.
• In contrast, a considerable decrease in the relative mRNA expression of IL-12 (by 15-fold) was observed after the second endotoxin challenge. This highlights the crucial role of IL-12 in the development of ET and shows that it gets significantly suppressed during the tolerance phase.
• The findings of this study provide a useful method for the ex vivo induction of ET in equine PBMCs and enhance the understanding of cytokine response in ET, particularly the reduced production of IL-12.