Study: Horses with Sarcoids have Elevated Treg Cell Levels

Study: Horses with Sarcoids have Elevated Treg Cell Levels

Treg marker expression was significantly higher in the sarcoid tumors and in the skin just around the tumors than in the skin of healthy horses.

Photo: Photos.com

Sarcoids—those unsightly tumors on horses’ skin—seem to have some things in common with human cervical cancer: Researchers have known for years that both diseases are related to a papilloma virus, but researchers from Switzerland recently showed that, like cervical cancer, sarcoid tumors appear to be affected by the number of “Tregs” present.

T-regulatory cells, or Tregs, are special white blood cells known as lymphocytes that play a central role in regulating immune responses. In cervical cancer patients, the higher the Treg count, the poorer the prognosis.

Results from the new Swiss study reveal that high Treg counts in equine sarcoid patients are present in sarcoids' microenvironment, explained Kathrin Mählmann, DrMedVet, of the Swiss Equine Medicine Institute, Agroscope, and Vetsuisse Faculty of the University of Bern. Mählmann presented her work at the 2014 Swiss Equine Research Day held April 10 in Avenches.

Whereas human cervical cancer is caused by the human papillomavirus, equine sarcoids are caused by the bovine papillomavirus. In 2011 medical researchers discovered the link between Tregs and cervical cancer prognosis, Mählmann said. In follow-up studies scientists observed an increase in Tregs at elevated malignancy and reduced Tregs in patients with milder lesions and spontaneous regression.

In their study Mählmann and colleagues employed 17 horses with sarcoids and collected biopsy samples from the lesion itself, the skin just around the lesion, and the skin far away from the lesion. They checked the expression of several kinds of cells that are involved in immune responses: IL10, IL4, and IFNy cytokines, as well as a Treg marker called FoxP3. They also checked for the amount of papillomavirus DNA in these samples. For comparison, the researchers also tested the skin of healthy horses and of horses with sweet itch (summer eczema), another immune-related skin disorder.

They found that the Treg marker expression was significantly higher in the sarcoid tumors and in the skin just around the tumors than in the skin of healthy and sweet itch horses, Mählmann said. IFNy expression was also higher in the lesions and surrounding skin. IL10 was higher only in the lesions, and IL4 was no different compared to controls.

As expected, papillomavirus DNA in sarcoid horses was highest in the tumor and lowest in the skin far away from the tumor, Mählmann said. However, what was surprising was that the amount of virus DNA was not related to the number of Tregs or other immune cells—or the severity of the disease.

“The increased expression of IL10 and FoxP3 in equine sarcoids indicates a local immunosuppression in the tumors,” Mählmann said. “The present studies confirm the role of Tregs in a virus-induced neoplasia (tumor formation) in the horse. The findings on the immunological front could help researchers develop effective immunological therapy.”

About the Author

Christa Lesté-Lasserre, MA

Christa Lesté-Lasserre is a freelance writer based in France. A native of Dallas, Texas, Lesté-Lasserre grew up riding Quarter Horses, Appaloosas, and Shetland Ponies. She holds a master’s degree in English, specializing in creative writing, from the University of Mississippi in Oxford and earned a bachelor's in journalism and creative writing with a minor in sciences from Baylor University in Waco, Texas. She currently keeps her two Trakehners at a competition stable east of Paris. Follow Lesté-Lasserre on Twitter @christalestelas.

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