Nephrotoxicity of Immune Checkpoint Inhibitors in Mice with a Human Immune System

IntroductionImmune checkpoint inhibitors (ICIs) enhance antitumor responses by blocking inhibitory receptors, including PD-1 and CTLA-4. Overactivation can trigger systemic toxicity akin to autoimmune diseases, including kidney manifestations. We sought to 1) profile immune signaling and 2) interrogate potential mechanisms of ICI-related kidney injury in a Human Immune System (HIS) tumor-bearing mouse model treated with nivolumab and ipilimumab. MethodsImmunodeficient BRGS (BALB/c-Rag2nullIl2r{gamma}nullSirpNOD) neonates were engrafted with human CD34+ cells to generate HIS-BRGS mice. Human MDA-MB-231 tumor cells were implanted subcutaneously; once tumors reached [~]150 mm3, mice received weekly intraperitoneal vehicle (PBS) or ICI (nivolumab 20 mg/kg + ipilimumab 10 mg/kg) for 4 weeks (Veh BRGS n=4; ICI BRGS n=6; Veh HIS-BRGS n=7; ICI HIS-BRGS n=7). Kidneys were evaluated by histopathology (H&E, TEM), flow cytometry for human immune phenotypes, multiplex ELISA (80 human proteins; 10 injury biomarkers), bulk RNA sequencing, and targeted qPCR. Pearson correlations identified predictors of histopathological injury. ResultsRenal vasculitis and interstitial nephritis were observed only in ICI-treated HIS-BRGS mice. These kidneys showed a shift toward CD4+ T-cell enrichment with an increased TNF- production capacity compared to CD8+ counterparts. Toxicity was accompanied by increased renal concentrations of human cytokines, chemokines, and soluble receptors. ICI treatment significantly elevated serine proteases (Granzyme A/B) and NGF-{beta}, while decreasing IL-4. Interstitial nephritis correlated with renal PD-1 and MIF. Renal vasculitis correlated with kidney PD-1, CCL1, MIF, Granzyme A, IL-15, and BAFF. Traditional injury biomarkers (KIM-1, NGAL) remained unchanged; however, a trending decrease in EGF was observed. ConclusionsOur study suggests that shifts in human T-cell populations and specific immune proteins could serve as promising biomarkers and mechanistic targets for ICI nephrotoxicity. The tumor-bearing HIS-BRGS mouse model reproducibly recapitulates the histopathological and immunological features of human ICI-induced nephrotoxicity and represents a validated preclinical platform for testing novel therapeutic interventions to preserve kidney function during cancer immunotherapy. Translational StatementImmune checkpoint inhibitor (ICI)-associated nephrotoxicity occurs in up to 25% of treated patients, yet the immunological mechanisms driving renal injury remain poorly characterized due to the scarcity of human biopsy material and the absence of robust preclinical models that recapitulate human immune responses. This study demonstrates that tumor-bearing humanized immune system (HIS) mice treated with combined nivolumab and ipilimumab reproducibly develop renal vasculitis and interstitial nephritis mediated by a human CD4+ T cell-dominant infiltrate, mirroring the clinicopathological features reported in patients with ICI-associated acute kidney injury. By integrating histopathology, flow cytometry, multiplex proteomics, and transcriptomics, we identify a coordinated immune network, including IL-15, CCL1, MIF, GZMA, and BAFF, that correlates with the severity of renal pathology and represents tractable mechanistic targets and candidate biomarkers. These findings provide a validated preclinical platform for dissecting irAE mechanisms and testing novel therapeutic strategies to preserve kidney function during cancer immunotherapy.