figHigh Spatial Resolution MALDI-MS Imaging in the Study of Membranous Nephropathy.

MALDI-MSI technology has advanced rapidly during recent years with the development of instruments equipped with low-diameter lasers that are suitable for high spatial resolution imaging. This may provide significant advantages in certain fields of molecular pathology where more specific protein fingerprints of individual cell types are required, such as renal pathology. Here we performed MALDI-MSI analysis of a cohort of MN patients among which patients either responded favourably (R; n = 6), or unfavourably (NR; n = 4), to immunosuppressive treatment (Ponticelli Regimen), employing a 10μm laser spot diameter. Specific tryptic peptide profiles of the different cellular regions within the glomerulus could be generated, similarly for the epithelial cells belonging to the proximal and distal tubules. Conversely, specific glomerular and sub-glomerular profiles could not be obtained whilst using the pixel size performed in previous studies (50μm). Furthermore, we highlight two proteins, Sonic Hedgehog (SHH) and α-smooth muscle actin (α-SMA), whose signal intensity and spatial localisation within the sub-glomerular and tubulointerstitial compartments differed between treatment responders and non-responders. The current study exemplifies the advantage of using high spatial resolution MALDI-MSI for the study of MN and highlights that such findings have the potential to provide complimentary support in the routine prognostic assessment of MN patients. This article is protected by copyright. All rights reserved.