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Peter Gouras, Kristy R Brown, Julie A Mattison, Martha Neuringer, Takayuki Nagasaki, Lena Ivert; Multilamellar bodies: Clues to their role in aging retinal epithelium. Invest. Ophthalmol. Vis. Sci. 2019;60(9):1240.
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© ARVO (1962-2015); The Authors (2016-present)
Multilamellar bodies (MLBs) are formed by the parallel apposition of lipid membranes from the endoplasmic reticulum, and are involved in the storage and release of lipids. They also act as monitors of faulty lipid metabolism, known as lipidosis, by increasing their numbers when lipid metabolism is defective as in lipid storage diseases or due to toxicity from cationic amphiphilic drugs. Our study describes MLB morphology and retinal distribution, and the effects of aging on MLB accumulation in the retinal epithelium.
Transmission electron microscopy was used to identify, quantify, and examine MLBs in young and old rhesus (Macaca mulatta) monkey retinal epithelium.
MLBs are present in the epithelium of all areas of the retina, concentrated in the basal region of the cell but absent in the apical region. MLBs accumulate near drusen in the retinal epithelium of old monkeys, yet it is absent in young animals. The MLBs contain large amounts of polyunsaturated fatty acids and morphology appears identical to MLBs in lung epithelium where the function is to extrude phospholipids across the cell membrane.
Aging leads to faulty lipid metabolism in the retinal epithelium as indicated by a large buildup of MLBs. This process is apparently confined to the basal region of the cell where most of the MLBs are located and where the earliest signs of macular degeneration occur. The morphological similarity between MLBs in lung and retinal epithelial cells suggests these organelles may perform similar functions in the two tissues, such as the extrusion of phospholipids. Yet, the pathological buildup of MLBs with age occurs only in the retinal epithelium, not in lung epithelium, which may be due to higher levels of toxic peroxides in the heavily polyunsaturated lipid environment of the retina.
This abstract was presented at the 2019 ARVO Annual Meeting, held in Vancouver, Canada, April 28 - May 2, 2019.
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