Compensated overexpression of procollagens alpha 1(I) and alpha 1(III) following perilla mint ketone-induced acute pulmonary damage in horses.

This research study aims to understand the behavior of certain genes in horses, specifically the collagen genes COL1AI and COL3AI, after induced acute pulmonary damage using perilla mint ketone. Despite observing an increase in expression levels of these genes, which are normally associated with fibrosis, no actual fibrosis was detected in the horses, suggesting the presence of unseen compensatory mechanisms.

Research Methodology

• The researchers injected six adult horses with perilla mint ketone (PMK) in a single intravenous dose of 6 mg/kg body weight, aiming to induce acute alveolar damage and interstitial lung disease. This was intended to create a model to monitor histopathological lesions and changes in gene expression relevant to pulmonary fibrosis.
• Before and at several time points after PMK administration (days 1, 4, 8, 11, 15, 18, 22, 25, and 29), lung biopsy samples were collected from the horses. Their observations were made through light and electron microscopy.

Observations and Results

• The researchers observed severe acute alveolar damage (days 1 to 4), followed by the proliferation of type II pneumocytes (days 4 to 11), and complete healing by approximately day 18.
• Due to unexpectedly severe clinical symptoms, two of the six horses had to be euthanized on days 9 and 11.
• COL1AI and COL3AI gene expressions were found to be upregulated (3- and 17-fold, respectively) between days 1 and 29 in all six horses. Additionally, the transforming growth factor (TGF)-beta was upregulated in two horses (2- and 4-fold, respectively), between days 4 and 18.
• Despite the upregulation of these genes indicating a strong activation of the pro-fibrotic pathway, none of the horses showed signs of interstitial fibrosis.
• A final examination on day 60 showed complete recovery of the lungs in the four surviving horses, again with no evidence of fibrosis.

Conclusions

• The researchers concluded that despite the strong activation of the pro-fibrotic genes COL1AI, COL3AI, and TGF-beta, no evidence of pulmonary fibrosis was observed in any of the horses. They suggest unidentified compensatory mechanisms may have prevented pulmonary fibrosis.
• This study offers a valuable insight into the potential of the horse body’s capacity to inhibit pulmonary fibrosis despite the high activation of pro-fibrotic genes. Further research is suggested to explore these potential compensatory mechanisms.