Increased interleukin-1beta mRNA expression in skin biopsies of horses with Culicoides hypersensitivity following challenge with Culicoides nubeculosus extract.

This research explores how the levels of Interleukin-1beta (IL-1beta), a primary skin protein involved in wound healing, change in horses with Culicoides hypersensitivity. It found that these horses showed a notable increase in IL-1beta levels after exposure to a Culicoides extract, a reaction not seen in horses without the allergy.

Background

• Interleukin-1beta (IL-1beta) is a primary skin protein that plays a significant role in skin cell differentiation, wound healing, and defence against pathogens.
• In humans, an abnormal increase of IL-1beta is linked to swelling (edema formation), increase of skin cell growth (epidermal hyperproliferation) and eczema (atopic dermatitis).
• The role of IL-1beta in causing swelling and allergic skin reactions in horses hasn’t been fully investigated. Particularly, there is a gap in research relating to Culicoides hypersensitivity (CHS)—an allergic skin reaction in horses caused by bites from the Culicoides fly.

The Experiment

• The researchers wanted to explore the mRNA expression of IL-1beta and its receptor antagonist IL-1RA in horse skin, specifically looking at horses affected and not affected by CHS, before and after exposure to a Culicoides fly extract.
• Their hypothesis was that the expression of the IL-1beta gene would significantly increase in horses with CHS when exposed to the Culicoides allergen.
• To test this, they took skin biopsy samples from horses both before and four hours after being injected with the extract.
• Their data was gathered using real time PCR, a common lab technique used for detecting gene expression, and they ensured the reliability of their data by normalising the genes of interest using three standard control genes.

Findings

• Before any challenge with the Culicoides extract, the research found no significant difference in levels of IL-1beta and IL-1RA in CHS-affected and non-affected horses.
• However, when injected with the extract, increases in IL-1beta mRNA were observed both in horses with a known history of CHS and clear clinical signs, and in non-affected horses.
• The difference recorded between the IL-1beta levels before and after exposure to the extract only held statistical significance in CHS-affected horses, indicating that these horses have a more pronounced reaction to the Culicoides extract.
• Levels of the IL-1RA mRNA did not show any changes following the injection of the extract in either group, suggesting that this protein doesn’t significantly contribute to the allergic reaction process.

Implications

• In contrast to eczema in humans, CHS in horses isn’t linked to increased baseline levels of IL-1beta mRNA.
• However, exposure to the Culicoides allergen stimulates the production of this protein in all horses, but this increase reaches a level of statistical significance only in horses who are affected by CHS and in an active stage of the disease.