Osteopontin and fibronectin levels are decreased in vitreous of autoimmune uveitis and retinal expression of both proteins indicates ECM re-modeling.
Authors: Deeg Cornelia A, Eberhardt Christina, Hofmaier Florian, Amann Barbara, Hauck Stefanie M
Journal: PloS one
Summary
Equine recurrent uveitis (ERU), a naturally occurring autoimmune condition that closely mirrors human autoimmune uveitis, involves T-cell-mediated inflammation within the eye that can progress to blindness if left unmanaged. Deeg and colleagues used Western blotting and immunohistochemistry to measure levels of two extracellular matrix proteins—fibronectin and osteopontin—in vitreous fluid and retinal tissue from horses with active ERU compared to healthy controls, employing cultured Müller cells to confirm cellular sources. Both proteins were significantly reduced in diseased vitreous, whilst retinal architecture showed marked remodelling: fibronectin normally localised to the inner limiting membrane became dispersed and fragmented during uveitis, and osteopontin expression shifted from a characteristic Müller cell pattern in healthy tissue to near-absence in inflamed gliotic Müller cells. These findings suggest that autoimmune uveitis triggers substantial breakdown of the retinal scaffold, potentially compromising the structural anchoring function of the inner limiting membrane and eliminating the neuroprotective role osteopontin normally provides. For equine practitioners, this work reinforces that ERU represents more than simple inflammatory infiltration; it involves progressive architectural damage to critical retinal support structures, which may explain why managing inflammation early is crucial to preserving vision and why late-stage disease often proves refractory to treatment.
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Practical Takeaways
- •ECM remodeling in ERU compromises the structural integrity of the inner retina, potentially affecting Müller cell anchoring and neuroprotective capacity
- •Loss of osteopontin in diseased tissue suggests reduced neuroprotection that may contribute to progressive vision loss in uveitis cases
- •Equine recurrent uveitis serves as a valuable spontaneous animal model for understanding autoimmune uveitis pathomechanisms relevant to clinical management
Key Findings
- •Fibronectin and osteopontin proteins are significantly reduced in vitreous of uveitic eyes compared to healthy controls
- •Inner limiting membrane (ILM) disintegration occurs in uveitis with fibronectin expression changing from organized to dispersed pattern
- •Osteopontin expression in Müller cells is nearly absent in uveitic retinas despite normal expression in healthy tissue
- •Primary equine Müller cells and eqMC-7 cell line demonstrated capacity to express both fibronectin and osteopontin in vitro