Abstract: Recurrent uveitis (RU), an autoimmune disease, is a leading cause of ocular detriment in humans and horses. Equine and human RU share many similarities including spontaneous disease and aberrant cytokine signaling. Reduced levels of SOCS1, a critical regulator of cytokine signaling, is associated with several autoimmune diseases. Topical administration of SOCS1-KIR, a peptide mimic of SOCS1, was previously correlated to reduced ocular pathologies within ERU patients. Unassigned: To further assess the translational potential of a SOCS1 mimetic to treat RU, we assessed peptide-mediated modulation of immune functions in vitro, using equine peripheral blood mononuclear cells (PBMC), and in vivo through topical administration of SOCS1-KIR into the eyes of experimental (non-uveitic) horses. Equine PBMCs from non-uveitic control and ERU horses were cultured with or without SOCS1-KIR pretreatment, followed by 72 hours of mitogen stimulation. Proliferation was assessed using MTT, and cytokine production within cell supernatants was assessed by Luminex. SOCS1-KIR or carrier eye-drops were topically applied to experimental horse eyes twice daily for 21 days, followed by enucleation and isolation of ocular aqueous and vitreous humor. Histology was used to assess peptide treatment safety and localization within treated equine eyes. Cytokine secretion within aqueous humor and vitreous, isolated from experimental equine eyes, was measured by Luminex. Unassigned: Following SOCS1-KIR pretreatment, cell proliferation significantly decreased in control, but not ERU-derived PBMCs. Despite differential regulation of cellular proliferation, SOCS1-KIR significantly reduced TNFα and IL-10 secretion in PHA-stimulated control and ERU equine PBMC. SOCS1-KIR increased PBMC secretion of IL-8. Topically administered SOCS1-KIR was well tolerated. Although SOCS1-KIR was undetectable within the eye, topically treated equine eyes had significant reductions in TNFα and IL-10. Interestingly, we found that while SOCS1-KIR treatment reduced TNFα and IL-10 production in healthy and ERU PBMC, SOCS1-KIR differentially modulated proliferation, IP-10 production, and RANTES within these two groups suggesting possible differences in cell types or activation status. Unassigned: Topical administration of a SOCS1 peptide mimic is safe to the equine eye and reduces ERU associated cytokines IL-10 and TNFα serving as potential biomarkers of drug efficacy in a future clinical trial.
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The research evaluates the potential of a protein mimetic, SOCS1-KIR, to treat recurrent uveitis (RU), an autoimmune eye disease, in horses and implicitly humans. The study found that this treatment, when topically applied, can safely regulate immune responses in the eye.
Introduction and Objectives
This study explores the effects of a protein mimic, SOCS1-KIR, in treating recurrent uveitis (RU). RU is an autoimmune disease that significantly impacts the vision of humans and horses. The focus of the study was on equine and human RU due to their peculiar commonalities, such as spontaneous occurrence of the disease and abnormal cytokine signaling.
The driving factor in choosing SOCS1-KIR for the study is the role the native protein, SOCS1, plays in regulating cytokine signaling. It has been noted that lower levels of SOCS1 are found in numerous autoimmune diseases.
SOCS1-KIR’s efficacy had previously been observed when it was applied topically, leading to reduced pathological ocular symptoms in patients suffering from equine recurrent uveitis (ERU).
The primary objective was to further confirm the potential usage of a SOCS1 mimetic to treat RU by assessing the modulation of immune functions of the mimic on equine peripheral blood mononuclear cells (PBMC). The team also aimed to observe the local effects within the eyes of experimental non-uveitic horses after topical administration of SOCS1-KIR.
Methodology
The investigation used PBMCs from non-uveitic control and ERU horses. These cells were cultured with or without pretreatment with the SOCS1-KIR peptide. The team then stimulated the samples with mitogens for 72 hours.
Multiple techniques were used to assess the effects of the pretreatment. MTT testing was used to evaluate cell proliferation while Luminex testing was performed on the supernatant from the cell cultures to evaluate cytokine production.
For the in vivo experiment, topical application of the SOCS1-KIR peptide (or a carrier-only control) was given to the eyes of experimental horses. This treatment was given twice per day for a 21-day period, followed by isolation of humors from the eyes and evaluation via histological analysis to assess treatment safety and localization of the peptide in the treated eyes.
Results
After pretreatment with SOCS1-KIR, noticeable reductions in cell proliferation were observed in control samples, but not in ERU-derived PBMCs. Nevertheless, the peptide significantly reduced TNFα and IL-10 secretion in both types of stimulated cells and increased production of IL-8.
Topical application of the SOCS1-KIR peptide was well-tolerated by the experimental horses’ eyes. Despite not being detectable within the eye, it was found that topically treated eyes exhibited significant reduction in TNFα and IL-10.
Conclusions
The investigation concludes that topical administration of the SOCS1 peptide mimic is safe for the eyes of horses and leads to a reduction in the cytokines IL-10 and TNFα, known to be associated with ERU. These cytokines could potentially be used as biomarkers for drug efficacy in future clinical trials.
Cite This Article
APA
Stafford LS, Plummer CE, Smith WC, Gibson DJ, Sharma J, Vicuna V, Diakite S, Larkin J.
(2025).
A peptide mimic of SOCS1 modulates equine peripheral immune cells in vitro and ocular effector functions in vivo: implications for recurrent uveitis.
Front Immunol, 15, 1513157.
https://doi.org/10.3389/fimmu.2024.1513157
Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, United States.
Plummer, Caryn E
Departments of Large and Small Animal Clinical Sciences, College of Veterinary Medicine, University of Florida, Gainesville, FL, United States.
Smith, W Clay
Department of Ophthalmology, College of Medicine, University of Florida, Gainesville, FL, United States.
Gibson, Daniel J
Capstone College of Nursing, University of Alabama, Tuscaloosa, AL, United States.
Sharma, Jatin
Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, United States.
Vicuna, Valeria
Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, United States.
Diakite, Sisse
Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, United States.
Larkin, Joseph
Microbiology and Cell Science, Institute of Food and Agricultural Science, University of Florida, Gainesville, FL, United States.
MeSH Terms
Animals
Horses
Uveitis / immunology
Uveitis / drug therapy
Uveitis / veterinary
Suppressor of Cytokine Signaling 1 Protein / immunology
Leukocytes, Mononuclear / immunology
Leukocytes, Mononuclear / drug effects
Leukocytes, Mononuclear / metabolism
Horse Diseases / immunology
Horse Diseases / drug therapy
Cytokines / metabolism
Peptides / pharmacology
Recurrence
Cells, Cultured
Grant Funding
S10 OD028476 / NIH HHS
Conflict of Interest Statement
JL3 is co-inventor on a patent, held by the University of Florida, on the SOCS mimetic technology, which is currently under licensing agreement to Arctic Therapeutics. The remaining authors declare that the research was conducted in the absence of any commercial or financial relationships that could be construed as a potential conflict of interest.
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