Billy G. Hudson, Ph.D. Vanderbilt University
The mechanisms of glomerulosclerosis have been elusive due to the technical challenges of studying individual glomerular components in situ or due to artifacts inherent to cell cultures and isolation techniques. The goal of this project is to document macromolecular expression change to specific glomerular structural components, an important step towards understanding molecular mechanisms of glomerulosclerosis. Specifically, we are examining the molecular changes that occur in the glomerulus and tubules under conditions of diabetic nephropathy and the effect of therapeutic pyridoxamine (PM) treatment. Advances in sample preparation and IMS spatial resolution have allowed us to determine mass signals specific to distinct cell types within the kidney. Advances in sensitivity have allowed imaging disease related molecular modifications. Using IMS, we have demonstrated identification and relative quantitation of disease related molecular changes in different renal regions, including individual glomeruli (Figure 1) and tubules, directly from thin kidney sections. Co-registration of IHC with IMS allowed for the determination of the microstructures where specific signals were localized . This determination has enhanced our understanding of the molecular mechanisms of kidney diseases and would not have been possible without the high spatial resolution protein imaging enabled through the technology research and development work.
Figure 1. High spatial resolution MS images from control and diabetic mice show distinct distributions of the major gangliosides NeuAc-GM3 and NeuGc-GM3. (A) MALDI TOF IMS ion images of m/z 1151.7 (NeuAc-GM3) and m/z 1167.7 (NeuGc-GM3) in the kidneys isolated from nondiabetic control mice, diabetic mice, and diabetic mice treated with PM. MALDI IMS was performed at 10 μm spatial resolution demonstrating that both lipids are localized exclusively to renal glomeruli. (B) IMS of the signal at m/z 1167.7 and corresponding PAS staining showing the specific localization of NeuGc-GM3 to glomerulus. Modified from: J Lipid Res 55 (7):1375-1385.
1. Grove KJ, Voziyan PA, Spraggins JM, Wang S, Paueksakon P, Harris RC, Hudson BG, Caprioli RM (2014) Diabetic nephropathy induces alterations in the glomerular and tubule lipid profiles. J Lipid Res 55 (7):1375-1385. PMCID: 4076088. Return to text.