A comparison of pro-inflammatory cytokine mRNA expression in equine bronchoalveolar lavage (BAL) and peripheral blood.

The study explored the variation of cytokine mRNA expressions in the bronchoalveolar lavage (BAL) and peripheral blood mononuclear cells (PBMC) in healthy horses. The focus was on identifying age-related differences and investigating the relationship between pro-inflammatory cytokine expression levels and BAL cytology.

Study Objectives

• The main objectives of this research were threefold. Firstly, the study aimed to identify age-related differences in the expression of pro-inflammatory cytokines in bronchoalveolar lavage (BAL) and peripheral blood mononuclear cells (PBMC). Second, the aim was to compare the expression of these cytokines between BAL and PBMC. Finally, the researchers sought to evaluate the relationship between BAL pro-inflammatory cytokine expression and BAL cytology, the study of cells and tissues.

Methodology

• The study took samples of BAL and PBMC cells from 66 horses. These samples were then stimulated with LPS and PGN, substances that typically provoke an immune response. The study then used quantitative Polymerase Chain Reaction (qPCR), a method for duplicating and analyzing small samples of DNA, to measure the expression of five specific cytokines: IL-1β, IL-6, IL-8, TNF-α and TLR-4.

Findings

• The study made several significant findings. Firstly, it found a significant decrease in the levels of cytokines IL-1β and IL-8 associated with age in the BAL samples. Additionally, there was a significant difference found in the amounts of cytokine mRNA expressed between the BAL and the PBMC samples. The researchers also found a meaningful relationship between TLR-4 and IL-8 expression levels in the LPS stimulated BAL samples and the ratio of neutrophils, a type of white blood cell, present in the BAL cytology samples.

Conclusion

• The discovery of a natural age-related decrease in pro-inflammatory cytokine expression within the bronchoalveolar lavage is a key conclusion. This finding opposes other age-related findings associated with peripheral blood mononuclear cells (PBMC), where pro-inflammatory cytokines are known to increase with age in both horses and humans due to a process known as ‘inflamm-aging’.