Activation of peripheral blood monocytes results in more robust production of IL-10 in neonatal foals compared to adult horses.

This research article discusses the notable differences in immune responses of foals and adult horses when exposed to the bacteria Rhodococcus equi. It reports that newly born horses, or foals, produce markedly more of the anti-inflammatory cytokine IL-10 when their monocytes are activated, compared to adults.

Introduction and Background

• The study focuses on the vulnerability of neonatal foals to Rhodococcus equi infection. Typically, mature horses are not susceptible to this bacterial infection, leading researchers to a theory of innate immunodeficiency in newborns.
• The research attempts to shed light on the factors contributing to this selective susceptibility to R. equi infection.

Focus on Monocyte Cells and Cytokines

• Monocyte cells, including macrophages and dendritic cells, were examined in the study. These cells play a crucial role in the body’s immune response, and their interaction with the cytokines IL-10, IL-12p35, and IL-12p40 was particularly studied.
• Cytokines are small proteins that are crucial in cell signaling. The study measures the cytokine mRNA production in response to activation with LPS and IFN-gamma, which are substances known to stimulate an immune response.

Key Findings

• This study found that activation of monocytes results in a more robust production of the IL-10 cytokine in neonatal foals compared to adult horses. Specifically, a two-fold log increase in the baseline cytokine mRNA expression of IL-10 in neonatal cells was reported.
• No significant difference was found regarding the mean cytokine mRNA expression of IL-12p35 and IL-12p40. This suggests that a decreased IL-12 synthesis in human neonates, often attributed to a defect in chromosomal remodeling preventing IL-12p35 gene transcription, does not likely occur in equine neonates.

Implications

• The findings suggest that equine cells of the monocyte lineage respond in age-dependent ways to in vivo activation, which ultimately can affect the regulation of both adaptive and innate immune responses.
• This difference in responses may have significant implications on the understanding of how neonatal foals and mature horses react differently to bacterial infections such as R. equi.