Age-related changes in cytokine expression by neutrophils of foals stimulated with virulent Rhodococcus equi in vitro.

This research article explores how the expression of certain proteins called cytokines, triggered by the presence of the bacteria Rhodococcus equi, changes in newborn foals as they age. The findings suggest that neutrophils, a type of white blood cell, trigger an inflammation response via these proteins, which varies depending on the age of the foal.

Research Context

• The research is focused on the response by neutrophils, a type of white blood cells, in newborn foals to infection with Rhodococcus equi, a bacterium that often causes pneumonia in young foals.
• While previous research has indicated that neutrophils are essential in counteracting R. equi infection, the mechanism through which neutrophils leverage their protective function has remained largely undefined.

Research Methodology

• The researchers investigated the differences in the expression of cytokines, proteins responsible for cell communication in immune responses, by unstimulated and R. equi-stimulated neutrophils obtained from newborn foals and subsequently at 2-, 4-, and 8-weeks of age.
• The expression levels of various types of cytokines (IFNgamma, TNFalpha, IL-6, IL-8, IL-12p40, IL-12p35, and IL-23p19) were measured both in the absence and presence of R. equi stimulation.

Key Findings

• Owing to the stimulation by virulent R. equi, the expression of IFNgamma, TNFalpha, IL-6, IL-8, IL-12p40, IL-12p35, and IL-23p19 cytokines in neutrophils significantly increased compared to the expression level in absence of stimulation.
• The study discovered significant age-related effects on the expression of IL-6, IL-8, IL-12p40, and IL-23p19.
• Neutrophils in newborn foals expressed more IL-6 and IL-8 compared to those in 2-, 4- and 8-week-old foals.
• Expression of cytokine IL-12p40 was similar in neutrophils from newborn and 2-week-old foals, regardless of stimulation. In contrast, the expression of IL-12p40 significantly increased in neutrophils from 4- and 8-week-old foals when stimulated by R. equi.

Implications

• The research demonstrated that foal neutrophils increase the mRNA expression of many pro-inflammatory cytokines in response to in vitro stimulation with R. equi, and the intensity of this expression is influenced by the foal’s age.
• The clinical significance of the age-related difference in R. equi-induced expression of IL-12p40 and its relation to susceptibility to R. equi pneumonia requires further investigation.