Distribution of Glycerophospholipids in the Adult Human Lens

Abstract

In humans, the age of fibre cells differs across the ocular lens, ranging from those formed before birth in the core of the lens to those formed just prior to death in the outer cortex. The distribution of glycerophospholipids in the adult human lens should reflect this range; however, limited data currently exists to confirm this hypothesis. Accordingly, this study aimed to determine the distribution of glycerophospholipids in adult human lens using mass spectrometry imaging. To achieve this, 20-µm thick slices of two human lenses, aged 51 and 67 were analysed by matrix-assisted laser desorption ionisation imaging mass spectrometry. The data clearly indicate that intact glycerophospholipids such as phosphatidylethanolamine, phosphatidylserine, and phosphatidic acid are mainly present in the outer cortex region, corresponding to the youngest fibre cells, while lyso-phosphatidylethanolamine, likely produced by the degradation of phosphatidylethanolamine, is present in the nucleus (older fibre cells). This study adds further evidence to the relationship between fibre cell age and glycerophospholipid composition.

Keywords: imaging mass spectrometry; lipidomics; phosphatidic acid; phosphatidylserine.

Figure 1

Distribution of lysophosphatidylethanolamine (LPE) and the most abundant phosphatidylethanolamines (PEs) in a 51-year-old and 67-year-old human lens.

Figure 2

Distribution images of PA and PS in a 51-year-old and 67-year-old human lens. All lipids were detected with [M − H]⁻ in negative ion mode. PA: phosphatidic acid, PS: phosphatidylserine.