Cloning of equine chemokines eotaxin, monocyte chemoattractant protein (MCP)-1, MCP-2 and MCP-4, mRNA expression in tissues and induction by IL-4 in dermal fibroblasts.

The researchers cloned four equine CC chemokines—eotaxin, monocyte chemoattractant protein (MCP)-1, MCP-2, and MCP-4—and assessed their mRNA expression in various horse tissues. They also recorded eotaxin’s probable role in recruiting eosinophils in the horse’s digestive tract and the possible involvement of these chemokines in equine skin allergic diseases.

Cloning of Equine Chemokines

• The research started with the cloning of four types of equine chemokines (eotaxin, MCP-1, MCP-2, and MCP-4). These chemokines are potent mediators of cell migration and are of significant importance in the body as they regulate inflammation and immune cellular responses.
• The cloned equine chemokines have a deep resemblance with their respective counterparts found in other species. This sets a basis to infer and understand how these chemokines might operate in different species.

mRNA Expression in Tissues

• The researchers studied the constitutive mRNA expression of the four chemokines in various tissues such as skin, lung, liver, spleen, jejunum, colon, and kidney in usual adult horses. The researchers used multiplex RT-PCR, a technique used for measuring the expression level of multiple genes at once.
• A comparison was made between this data and eosinophil counts in the same tissue samples. Eosinophils are a type of white blood cells that play essential roles in the immune system.

Expression and Function of Chemokines

• The results indicate that eotaxin mRNA is solely expressed in the jejunum and colon, where there are substantial numbers of eosinophils. This finding suggests that eotaxin might be playing a pivotal role in recruiting eosinophils in the normal digestive tract of the horse.
• MCP-1 and MCP-4 were expressed in all tissues, whereas MCP-2 was only identified in certain samples of the lung, spleen, liver, and kidney.

Chemokines and Allergic Diseases

• This study also reports the early activation (at 2 hours) of equine eotaxin and MCP-4 and the up-regulation of MCP-1 by a protein called interleukin-4 in dermal fibroblasts. Dermal fibroblasts are cells within the dermis layer of skin which are responsible for generating connective tissue.
• This suggests a probable role of these chemokines in equine skin allergic diseases. More research in this direction can open new ways to understand allergic conditions and spot potential therapeutic targets.