Spatial Transcriptomics and Mechanisms of Immune Checkpoint Inhibitor-Associated Interstitial Nephritis

Introduction: Immune checkpoint inhibitor-associated acute interstitial nephritis (ICI-AIN) is the most common finding on histopathology among patients with ICI-associated acute kidney injury (ICI-AKI). Patients with ICI-AIN often have T cell-dominant infiltration of the kidney and high tissue levels of CXCR3 ligands such as CXCL9, 10, and 11; however, the mechanisms of inflammation in ICI-AIN are not well-understood. Methods: We applied a subcellular spatial transcriptomics platform (Xenium Prime 5K) to compare the cellular composition of kidney biopsy tissue from patients with ICI-AIN with ICI-treated patients with acute tubular necrosis (ICI-ATN). Results: Across 8 kidney biopsy specimens (4 with ICI-AIN, 4 with ICI-ATN), we analyzed 332,000 cells, comprising kidney parenchymal cells and infiltrating immune cells. Using a spatially aware cellular neighborhood-based classification, we identified cellular niches corresponding to each part of the nephron, in addition to unique fibrotic and inflammatory niches. Gene pathway analysis identified interferon-gamma (IFN-γ) and/or signal transducer and activator of transcription 1 (STAT1) signaling as strongly increased in ICI-AIN compared with ICI-ATN. Although all inflammatory niches were overrepresented in ICI-AIN, CD8+ T cell infiltration, and proinflammatory myeloid cells were the dominant immune niches. Spatial niche crosstalk analysis revealed that CD8+ T cell-derived IFN-γ likely induced a proinflammatory program in myeloid cells, with increased production of CXCL9, 10, and 11. Furthermore, IFN-γ signaling in ICI-AIN was associated with reduced oxidative phosphorylation in kidney tubular niches. Conclusion: T cells as potential drivers of ICI-AIN.