Interleukin 31 mediates pruritus in horses.

This study explores the influence of Interleukin 31 (IL-31) on itchiness (pruritus) in horses and suggests it as a potential therapeutic target for equine allergic itchiness.

Research Methodology

• Being a part of the study, the researchers first confirmed the sequences of equine IL-31 mRNA via sequencing.
• A recombinant variant of eIL-31 was manufactured using both mammalian and bacterial expression systems. Recombinant refers to any DNA formed through laboratory methods rather than occurring naturally.
• For over a year (November 2019 – February 2021), 12 healthy horses of ages between 6 and 10 years having no previous history of allergic skin disease were injected IntraDermally (ID) with either eIL-31 and saline in two separate challenge studies.
• Pruritus-associated behaviors were tracked and recorded for at least 15 minutes before the injection and for 4 hours post the injection.
• Monocytes, a type of white blood cell, from 3 horses showing pruritus symptoms and suffering from insect bite hypersensitivity and/or atopic dermatitis, were induced with bacterial eIL-31 resulting in an increased phosphorylation of signal transducer and activator of transcription 3 (STAT3). The measurement for this was taken using techniques such as western blot and AlphaLISA.

Research Findings

• The eIL-31 resulted in higher purity when produced in a bacterial system compared to a mammalian system, as indicated by purity percentages (95% vs 70%).
• Pruritus (itching behavior) was noticed with the injection of both forms of eIL-31. Injections using mammalian eIL-31 resulted in mild pruritus, while the bacterial eIL-31 induced marked pruritus in some horses and a milder response in others.
• The majority of the pruritus (itching behavior) was observed to occur after two hours post the injection, and then started to subside by 4 hours post-injection.
• The bacterial version of eIL-31 prompted the phosphorylation of STAT3 within the monocytes of allergic horses. Phosphorylation of STAT3 is a cellular process to regulate cell growth and division, and increased phosphorylation could indicate cellular changes due to eIL-31 stimulation.

Research Conclusion

• This study provides proof-of-concept evidence that IL-31 mediates, or is a potential cause of, pruritus and is associated with STAT3 phosphorylation in horses, similar to other species.
• The findings imply that Interleukin 31 is a promising target for therapeutic methods intended to treat equine allergic pruritus.