Microglia in the primate macula: specializations in microglial distribution and morphology with retinal position and
Janani Singaravelu1, Lian Zhao1, Robert N Fariss2
1Unit on Neuron-Glia Interactions in Retinal Disease, National Eye Institute, National Institutes of Health, Building 6, Room 215, Bethesda, MD, 20892, USA.
Abstract:
Microglia, the principal resident immune cell in the retina, play constitutive roles in immune surveillance and synapse maintenance, and are also associated with retinal disease, including those occurring in the macula. Perspectives on retinal microglia function have derived largely from rodent models and how these relate to the macula-bearing primate retina is unclear. In this study, we examined microglial distribution and cellular morphology in the adult rhesus macaque retina, and performed comparative characterizations in three retinal locations along the center-to-periphery axis (parafoveal, macular, and the peripheral retina). We found that microglia density peaked in the parafoveal retina and decreased in the peripheral retina. Individual microglial morphology reflected macular specialization, with macular microglia demonstrating the largest and most complex dendritic arbors relative to other retinal locations. Comparing retinal microglia between young and middle-aged animals, microglial density increased in the macular, but not in the peripheral retina with age, while microglial morphology across all locations remained relatively unchanged. Our findings indicate that microglial distribution and morphology demonstrate regional specialization in the retina, correlating with gradients of other retinal cell types. As microglia are innate immune cells implicated in age-related macular diseases, age-related microglial changes may be related to the increased vulnerability of the aged macula to immune-related neurodegeneration.
Insights
Retinal microglia show specialized distribution and morphology, particularly in the macula. Age increases macular microglia density, potentially linking to age-related macular diseases.
Area of Science:
- Ophthalmology
- Neuroscience
- Immunology
Background:
- Microglia are crucial retinal immune cells involved in surveillance and synapse maintenance.
- Understanding retinal microglia function in primates, especially the macula, is vital for disease insights.
- Rodent models offer limited understanding of primate retinal microglia.
Purpose of the Study:
- To investigate microglial distribution and morphology in the rhesus macaque retina.
- To compare microglia across parafoveal, macular, and peripheral retinal regions.
- To assess age-related changes in retinal microglia.
Main Methods:
- Examined microglial distribution and cellular morphology in adult rhesus macaque retinas.
- Performed comparative analysis across three retinal locations: parafoveal, macular, and peripheral.
- Compared microglia between young and middle-aged animals.
Main Results:
- Microglia density was highest in the parafoveal retina, decreasing towards the periphery.
- Macular microglia exhibited larger, more complex dendritic arbors than those in other regions.
- Microglial density increased in the macula with age, while morphology remained stable across all locations.
Conclusions:
- Retinal microglia display regional specialization in distribution and morphology, correlating with other retinal cell types.
- Age-related alterations in macular microglia may contribute to the macula's susceptibility to immune-related neurodegeneration.
- These findings provide insights into primate retinal microglia relevant to age-related macular diseases.
