Hayashi, S.; Takeuchi, M.; Nakano, T.; Setoyama, D.; Singh, S. A.; Sonawane, A. R.; Iwamoto, T.; Kishimoto, H.; Tsuchimoto, A.; Yamada, S.; Kang, D.; Ago, T.; Kitazono, T.; Aikawa, M.; Kunisaki, Y.

Focal segmental glomerulosclerosis (FSGS) is a major cause of glucocorticoid-resistant nephrosis, yet its pathogenesis remains unclear. To define the molecular and cellular landscape of FSGS, we employed multi-omics approaches on independent human kidney biopsy cohorts. Proteomics revealed enhanced immune and complement activation. Spatial transcriptomics using a target gene panel constructed from the proteomics highlighted alternative pathway activation driven by complement factor D as a prominent feature. Complement activation emerged in glomeruli alongside altered signaling in podocytes and parietal epithelial cells (PECs): Podocytes displayed reduced PECAM1 and elevated macrophage migration inhibitory factor (MIF) signaling, and PECs display complement and collagen signaling as early events, and progressively acquired cellular activation, prompting glomerular fibrosis. These pathogenic signals propagated into adjacent interstitial regions, paralleling immune cell infiltration and fibrosis. These results uncover dynamics of dysregulated intercellular interactions originated from podocyte and PECs underlying the pathogenesis of FSGS, which provides insights into potential stage-specific interventions.