Retinal glycoprotein enrichment by concanavalin a enabled identification of novel membrane autoantigen synaptotagmin-1 in equine recurrent uveitis.
Authors: Swadzba Margarete E, Hauck Stefanie M, Naim Hassan Y, Amann Barbara, Deeg Cornelia A
Journal: PloS one
Summary
Equine recurrent uveitis (ERU) is a spontaneous autoimmune condition affecting the eye, and whilst several disease-associated autoantigens have been identified, membrane proteins had remained conspicuously absent from the roster until now. Researchers used concanavalin A affinity chromatography to enrich retinal glycoproteins, reasoning that since many membrane proteins are glycosylated, this selective enrichment would improve detection of low-abundance autoantigens that conventional methods might miss. Through this targeted approach combined with mass spectrometry and serological validation, synaptotagmin-1—a calcium-sensing protein essential for neurotransmitter release at synaptic vesicles—emerged as the first identified membrane-associated autoantigen in ERU, with antibodies present in a high proportion of affected horses. Notably, synaptotagmin-1 expression was downregulated to approximately 24% of normal levels in most ERU-affected retinas, suggesting the autoimmune response disrupts the neuromodulatory mechanisms governing retinal function. For equine practitioners, this discovery points toward dysregulated neurotransmitter signalling as a previously underappreciated mechanism in ERU pathogenesis, potentially opening new avenues for diagnostic biomarkers and targeted therapeutic interventions aimed at restoring retinal neuronal communication.
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Practical Takeaways
- •ERU involves autoimmune attack on synaptic signaling proteins in the retina, suggesting mechanisms beyond conventional retinal pigment epithelium-targeted immunity may be relevant to disease pathogenesis
- •This membrane autoantigen discovery provides new diagnostic and therapeutic targets for understanding ERU as a spontaneous model of human autoimmune uveitis
- •Neurotransmitter dysregulation in ERU may explain visual deficits and could inform future treatment strategies targeting synaptic dysfunction
Key Findings
- •Synaptotagmin-1 identified as the first membrane-associated autoantigen in equine recurrent uveitis using ConA affinity enrichment and mass spectrometry
- •Synaptotagmin-1 is highly prevalent as an autoantigen validated by ELISA in ERU patient sera
- •Synaptotagmin-1 expression downregulated to 24% in majority of ERU-affected retinas compared to controls
- •Dysregulation of retinal neurotransmitter release mechanism implicated in ERU pathophysiology