BACKGROUND Acute interstitial nephritis (AIN) is a common cause of acute kidney injury (AKI), but the diagnosis may be missed as kidney biopsies are rarely obtained when acute tubular injury (ATI) is suspected.METHODS The Kidney Precision Medicine Project is a cohort study that obtains kidney biopsies from individuals with AKI, which undergo pathologic and molecular interrogation. We compared ATI and AIN cases among the first 60 AKI participants.RESULTS On clinicopathologic adjudication, 30 patients (50%) had a primary adjudicated diagnosis of ATI, 13 (22%) patients had AIN, 9 (15%) had diabetic nephropathy, and 3 (5%) had other conditions. There were increased interstitial white blood cells and tubulitis (P < 0.05 for both) in AIN compared with ATI. Prior to biopsy, the treating clinician suspected ATI in 83% of the cases with adjudicated ATI, while the treating clinician suspected AIN in 54% of the cases with AIN. Tissue transcriptomic signatures showed enrichment of proinflammatory signaling and increased expression of CXCL9, a chemokine induced by IFN-γ, in myeloid cells of participants with AIN. CXCL9 localized to inflammatory infiltration in spatial transcriptomic data.CONCLUSION Adjudication of kidney biopsies revealed distinct pathologic and molecular profiles between ATI and AIN. Kidney biopsy should be considered more frequently in AKI, as AIN is clinically underrecognized.TRIAL REGISTRATION ClinicalTrials.gov NCT04334707.FUNDING National Institute of Diabetes and Digestive and Kidney Diseases grants U01DK133081, U01DK133091, U01DK133092, U01DK133093, U01DK133095, U01DK133097, U01DK114866, U01DK114908, U01DK133090, U01DK133113, U01DK133766, U01DK133768, U01DK114907, U01DK114920, U01DK114923, U01DK114933, U24DK114886, UH3DK114926, UH3DK114861, UH3DK114915, and UH3DK114937.
Jennifer A. Schaub, Rajasree Menon, Ricardo Melo Ferreira, Elizabeth Kiernan, Insa M. Schmidt, Christine P. Limonte, Soumya Yennapureddy, Ying-Hua Cheng, Leal Herlitz, Avi Z. Rosenberg, Joel M. Henderson, Kelly D. Smith, Jeffrey B. Hodgin, Edgar Otto, Gilbert W. Moeckel, Lloyd G. Cantley, Suman Setty, Ulysses G.J. Balis, Dawit Demeke, Agnes B. Fogo, Andrew S. Bomback, Vivette D. D’Agati, Isaac E. Stillman, Jose R. Torrealba, Allen R. Hendricks, Erika Bracamonte, Vanessa Moreno, Pavan Bhatraju, Amy K. Mottl, Frank C. Brosius, Bijin Thajudeen, Steven G. Coca, Paul M. Palevsky, Parmjeet S. Randhawa, Raghavan Murugan, Laura Barisoni, Charles E. Alpers, Steven Menez, F. Perry Wilson, Dennis G. Moledina, Michael T. Eadon, Matthias Kretzler, Jonathan Himmelfarb, Chirag R. Parikh, the Kidney Precision Medicine Project