Sphingolipids and ceramides of mouse aqueous humor: Comparative profiles from normotensive and hypertensive DBA/2J mice

Abstract

Purpose To identify the sphingolipid and ceramide species and their quantitative differences between normotensive and hypertensive intraocular pressure states in DBA/2J mouse aqueous humor (AH). Methods Normotensive and hypertensive AH was sampled from mice by paracentesis. Lipid extraction was performed using modifications of the Bligh and Dyer method. Protein concentration was estimated using the Bradford colorimetric assay. Sphingolipids and ceramides were identified and subjected to ratiometric quantification using appropriate class specific lipid standards on a TSQ Quantum Access Max triple quadrupole mass spectrometer. Results The comparative profiles of normotensive and hypertensive DBA/2J mouse AH showed several species of sphingomyelin, sphingoid base, sphingoid base-1-phosphate (S1P) and ceramides common between them. A number of unique lipids in each of the above lipid classes were also identified in normotensive AH that were absent in hypertensive AH and vice versa. Conclusion A number of sphingolipid and ceramide species were found to be uniquely present in normotensive, but absent in hypertensive AH and vice versa. Further pursuit of these findings is likely to contribute towards expanding our understanding of the molecular changes associated with increased intraocular pressure (IOP) and glaucoma.

Endogenous ocular lipids as potential modulators of intraocular pressure

“…Taken together with their slow rate of growth and altered gene expression, it is likely that glaucomatous TM cells differ in composition including that of lipids. The secreted lipids in AH similarly are different in glaucoma compared to controls, despite the fact that they may have been contributed by many different tissues in the anterior chamber …”

“…Samples were injected as direct infusion using a Triversa Nanomate driven by Chipsoft 8.3 (Advion Inc). The samples were run with and without addition of lipid standards for each class of lipids analysed as done in our previous studies . In addition, an unrelated lipid standard was used during extraction.…”

“…Normal AH has been shown to contain diverse phospholipids (PLs) . The TM and AH phospholipids and sphingolipids of human control and POAG as well as normotensive and ocular hypertensive DBA/2J mouse have been previously analysed using moderate‐resolution mass spectrometers …”

The Role of Deimination in Regenerative Reprogramming of Neurons

“…An internal standard was used for ratiometric quantification in a two-step process [63,64]. Briefly, in the first step, the most abundant lipids in the class were quantified using internal standards, and the measurements from the first step were used for quantification of low-abundance species in the second step [64,65,57]. The internal standards were procured from and made by Avanti Polar Lipids (Alabaster, AL) in conjunction with LipidMaps (www.lipidmaps.org) specifically for LC-MS quantification use.…”

Thermally labile components of aqueous humor potently induce osteogenic potential in adipose-derived mesenchymal stem cells

“…AH is a complex mixture of proteins, lipids, salts, and other small molecules (Cousins et al, 1991; De Berardinis et al, 1965; Duan et al, 2010; Edwards et al, 2014; Greiner et al, 1991; Iyer et al, 2012; Knisely et al, 1994; Lee et al, 1977; Rao et al, 2000; Russell et al, 2001; Tripathi et al, 1989). Several of these solutes have been previously implicated in osteogenesis, including ascorbate and glucocorticoids (Bellows et al, 1987; Bellows et al, 1986; Herbertson and Aubin, 1995; Maniatopoulos et al, 1988; Tenenbaum and Heersche, 1982), growth-factor like lipids such as lysophosphatidic acid (LPA) (Liu et al, 2010), and the protein myocilin (Kwon et al, 2013).…”