The integral duties of the ocular immune system
New Orleans, La. — Many know that the body’s immune system impacts the eye and vice versa. However, what about the eye’s immunity? What roles can it perform? What secrets lie within it that could possibly change the way clinicians respond to ocular diseases? Two studies presented this week at the Association for Research in Vision and Ophthalmology’s (ARVO) 2023 Annual Meeting in New Orleans, La. delved into these questions to demonstrate the significance of the eye’s immunity and the necessity for more research in this realm.
The choroid and autoimmune uveitis
Uveitis is an inflammation of the uvea, the middle layer of the eye composed of the choroid, iris, and ciliary body. Autoimmune uveitis (AU) often leads to vision impairment and blindness if not detected early and treated properly. Cases of AU are connected to issues with the immune system and can manifest either in the eyes alone or in conjunction with another systemic autoimmune or autoinflammatory condition.
Many studies view AU, even eye-limited disease, as a systemic disease, an illness that affects the whole body instead of one organ or body part. Thus, the contribution of local immunity in the eyes to AU has been largely ignored. James Walsh, MD, PhD, from the Washington University in St. Louis, Mo. wanted to comprehend how local immune cells in the eye are activated during AU to gain further insights into the development of this disease. They injected different types of tracers into the eye to track the movement of antigens and cells. They monitored areas where these tracers appeared, as well as how the immune response evolved during the disease.
They discovered that antigens from the eye drained not just to systemic immune organs, but also to the choroid. There in the choroid, they found many innate and adaptive immune cells, and during inflammation T cells, a vital immune component of AU, accumulated locally prior to appearing in the retina. This development suggested that the choroid may serve as a site where immunity is active prior to retinal involvement.
Walsh conveyed “this study shows that local border immunity in the eye is more important than previously recognized and could lead to development of new therapeutic targets for autoimmune uveitis.”
- Abstract title: The choroid coordinates local ocular immune responses during autoimmune uveitis
- Presentation start/end time: Tuesday, April 25, 9:30 – 9:45am CT
- Location: 243
- Presentation number: 2455
New study demonstrates protective retinal immune cells
The most common cause of blindness in older people is age-related macular degeneration (AMD), an ocular disease that deteriorates the center of the retina, the macula. Multiple genetic studies have linked immune system functions to AMD and the genes that encode them. Yet, how the immune cells function in the development of AMD is poorly understood. Lead researcher Daniel Saban, PhD, and others decided to change this by examining the role of microglia, cells that are the main line of immune defense in the central nervous system (CNS), thus the retina.
Their study was conducted on donated human eyes from postmortem AMD and non-AMD patients. They separated and analyzed the myeloid cells from both patients. Then Saban and the team examined the gene expression of the myeloid cells and compared them between the two groups. They unearthed a notable microglial population that were aggregated in the areas of degeneration. Their previous research in animal models showed that this population defended the retinal tissues against disease-related harm.
"Researchers at Duke identified a type of immune cell prevalent in people with age-related macular degeneration (AMD) that helps protect against blinding degenerative diseases in mouse models.” Saban started, “A better understanding of these novel retinal immune cells may pave the way to new drug strategies for mitigation of retinal degeneration in patients."
- Abstract title: Molecular Signature of Subretinal Microglia Signifies an Adaptive Response that is Protective in Retinal Degeneration (RD) Mice and is Conserved in Human AMD
- Presentation start/end time: Tuesday, April 25, 11:45am – 12:00pm CT
- Location: 243
- Presentation number: 2862
The Association for Research in Vision and Ophthalmology (ARVO) is the largest eye and vision research organization in the world. Members include approximately 10,000 eye and vision researchers from over 75 countries. ARVO advances research worldwide into understanding the visual system and preventing, treating and curing its disorders. Learn more at ARVO.org.