Insulin-dependent (type I) diabetes mellitus (IDDM) is an autoimmune disease with multifactorial etiology. Komeda Diabetes-Prone (KDP) rats are excellent animal models to apply for this type of study. Here we demonstrate a comprehensive matrix-assisted laser desorption/ionization (MALDI) imaging mass spectrometry (IMS) approach to study the molecular distribution of proteins in type I diabetic kidney from KDP rats. Especially, we ask if the minimal changes of diabetic kidney with an autoimmune etiology at early stages of the disease progression can be traced with MALDI-IMS.
Kidneys from KDP and KND (Komeda non-diabetic) rats at 7 weeks of age were resected and snap-frozen in liquid nitrogen. 10 µm cryosections were cut and transferred to Indium-Tin-Oxide (ITO) coated glass slides. a-Cyano-4-hydroxycinnamic acid (HCCA) was uniformly deposited on the slide using the ImagePrep device and measured using rapifleX tissuetyper with a spatial resolution of 50 µm in linear mode. Ions were detected in a mass range of m/z 800 to 3000. For Protein ID experiments, trypsin was sprayed at room temperature using the same apparatus. The multivariate analysis was done for obtained data.
In this study, in order to find early proteomic markers of minimal diabetic renal insufficiency, we have analyzed KDP rats at 7 weeks of age by comparing with those from KND rats. Deeper analysis using supervised statistical evaluations in combination with an in-depth shotgun proteomics will reveal a number of candidate markers and marker proteomic signature directly off-tissue that may be related to early histologic changes in this model. Comprehensive proteomics IMS analysis on kidney sections from KDP rats will clarify early type I diabetic nephrotic changes at peptide and protein level.
Keywords Imaging Mass Spectrometry, type I diabetes model, KDP rat, kidney