Effects of in vitro exposure to hay dust on expression of interleukin-23, -17, -8, and -1beta and chemokine (C-X-C motif) ligand 2 by pulmonary mononuclear cells from horses susceptible to recurrent airway obstruction.

The research study aimed to understand the effects of hay dust on the gene expression of certain types of cytokines in horses prone to recurrent airway obstruction (RAO) and healthy horses. The study found that hay dust exposure amplified the gene expression of all cytokines in horses, but severity was not different between RAO-susceptible and healthy horses. Exposure to certain substances resulted in increased gene expression in RAO-prone horses compared to control, but these findings weren’t significantly different. Notably, the characteristic inflammation of RAO was not linked to increased gene expression of chemokine in pulmonary cells in RAO-susceptible horses.

Study Design

• The researchers examined gene expression for cytokines in pulmonary mononuclear cells isolated from both healthy horses and those susceptible to recurrent airway obstruction (RAO).
• The target group consisted of six RAO-susceptible and five healthy horses.
• Bronchoalveolar lavage cells from horses stabled and fed on dusty hay for 24 hours were collected.
• These cells, once separated from neutrophils, were exposed to solutions of PBS, hay dust, lipopolysaccharide, or B-glucan for a day.
• Gene expression for IL-17, IL-23 (p19 and p40 subunits), IL-8, IL-1B, chemokine (C-X-C motif) ligand 2 (CXCL2), and B-actin was measured using real-time reverse transcription PCR assays.

Findings

• Without treatment, the inherent expression of target genes in bronchoalveolar lavage cells didn’t differ between the two groups.
• Exposure to hay dust solution increased by more than twofold the gene expression of all cytokines in cells from both groups of horses. However, the intensities of these increases didn’t differ between the groups.
• Exposure to lipopolysaccharide solution caused an increase in gene expression of IL-8, CXCL2, and IL-1B in cells from RAO-susceptible horses. Nevertheless, this increase wasn’t significantly different from that in cells from control horses.
• Exposure to B-glucan solution didn’t have any effect on gene expression in cells from either group of horses, as compared to gene expression when the cells were exposed to PBS.

Conclusions

• The study’s results indicate no significant association between the acute pulmonary neutrophilia characteristic of RAO and an increase in gene expression of chemokines in pulmonary mononuclear cells from RAO-prone horses.
• The study provides useful insights for understanding the genetic aspect of RAO in horses and the role of environmental factors in its development.