Effects of in vitro exposure to hay dust on the gene expression of chemokines and cell-surface receptors in primary bronchial epithelial cell cultures established from horses with chronic recurrent airway obstruction.

This research article explores the impact of hay dust exposure on genetic expression related to inflammation and immune responses in the bronchial epithelial cells of horses, particularly those with chronic recurrent airway obstruction (RAO). Researchers found that in vitro exposure to hay dust triggered the expression of certain chemokines and interleukins, which may contribute to airway inflammation in horses riding to RAO.

Research Methodology

• Primary bronchial epithelial cell cultures (BECCs) were established using biopsy specimens from six horses affected with RAO and six healthy horses.
• These five-day-old BECCs were then exposed to various treatments including soluble hay dust, lipopolysaccharide (LPS), beta-glucan, or a phosphate-buffered saline (PBS) solution for 6 or 24 hours. PBS solution was used as a control.
• The researchers then measured the gene expression of various chemokines, interleukins, and cell-surface receptors (CSR), such as IL-8, IL-1beta, CXCL2, toll-like receptor 2 and 4, IL-1 receptor 1, and glyceraldehyde 3-phosphate dehydrogenase, using a kinetic PCR assay.

Research Findings

• They found that BECC exposure to PBS solution did not cause any significant alternation in chemokine or CSR expression in either group of horses.
• Whereas, a 6-hour exposure to hay dust or LPS significantly increased the gene expression of IL-8, CXCL2, and IL-1beta over three-fold in the cultured cells. However, when extended to 24 hours, only IL-1beta gene expression was observed to be up-regulated over three-fold.
• No significant influence was observed on CSR gene expression following any treatments.
• The gene expression of chemokines or CSR did not significantly differ between BECCs from RAO-affected and healthy horses, apart from a 3.7-fold upregulation of CXCL2 in BECCs from RAO-affected horses after a 6-hour hay dust treatment.
• At the 24-hour point, CXCL2 gene expression was downregulated in all BECCs.

Conclusions

• Based on these findings, the researchers concluded that the upregulation of epithelial CXCL2 in response to hay dust exposure could potentially trigger early airway neutrophilia (a condition characterized by an excessive level of neutrophils, a type of white blood cell, in the blood), in horses with RAO.
• This implies that hay dust exposure might play a significant role in exacerbating chronic airway obstruction in horses.