N-Glycan MALDI MSI Differentiates Kidney Glomerular Disease Phenotypes.

Lupus nephritis (LN) and diabetic nephropathy (DN) are leading causes of kidney failure, characterized by distinct yet overlapping patterns of glomerular injury. While histopathology remains central to diagnosis, it provides limited insight into the underlying molecular remodeling. Here, we applied matrix-assisted laser desorption/ionization mass spectrometry imaging (MALDI-MSI) to define the spatial N-glycan landscape across human kidney biopsies from healthy controls (HCs) and patients with DN or LN. Whole-biopsy analyses demonstrated that identical N-glycan species adopt distinct spatial distributions depending on the disease context. Healthy kidneys were enriched in bisected N-glycans, DN in biantennary and sialylated species, and LN in fucosylated and paucimannose N-glycans, reflecting divergent enzymatic and pathogenic pathways. Glomerulus-resolved analyses substantially enhanced discrimination among disease groups, revealing previously undetected differences and highlighting disease-specific molecular phenotypes that were masked at the whole biopsy level. Notably, glomeruli classified as histologically normal exhibited distinct N-glycan signatures across disease states, indicating that molecular remodeling occurs independently of the overt structural changes. Within biopsies, N-glycan class composition shifted systematically with glomerular injury, with DN displaying more uniform remodeling and LN demonstrating greater phenotypic heterogeneity. Mixed-effect modeling confirmed significant morphology-dependent differences while accounting for biopsy-level clustering. MALDI-IHC analysis further supported phenotype-specific molecular differences across the glomerular subtypes. Collectively, these findings establish glomerular N-glycan architecture as a major driver of glycomic divergence across kidney diseases and position spatial N-glycomics as a translational approach for defining disease-specific molecular signatures within intact renal tissues.