Spatial transcriptomics and single cell sequencing identifies a unique injury associated resident macrophage subpopulation and reveals differential response to injury

Abstract

Abstract Acute kidney injury (AKI) is a growing concern in the U.S. and globally. Despite recovery of kidney function, patients remain at increased risk for developing chronic kidney disease (CKD). The cause of this increased risk is unknown and biomarkers to determine kidney injury are severely lacking. A potential candidate is the network of kidney resident macrophages interwoven throughout the tissue, and specifically a subpopulation of kidney injury associated macrophages (KIA) we first identified to appear after AKI and lack MHC II expression. KIA cells were localized within the tissue using Visium Spatial Transcriptomics and flow cytometry. Comparison of KIA cell kinetics between AKI and CKD indicated a correlation between the presence of KIA cells and the persistence of injury. Additionally, KIA cells have localized to the sight of greatest injury following an ischemic event. As kidney function recovers, KIA cells decrease in number and return to quiescent levels by 14 days post injury. In contrast, in the severe CKD model, KIA cells persist for up to six weeks, composing approximately 20% of the total kidney resident macrophage population. A less severe version of CKD results in fewer KIA cells but similar persistence, indicating appearance of KIA cells directly correlates with injury severity. Targeting KIA cells to either enhance or negate their function is a possible therapeutic target to reduce the risk of developing CKD following AKI. As we have identified KIA cells in multiple models of kidney injury, in the future they should be investigated as a potential injury biomarker. We hypothesize that KIA cells are uniquely involved in the pathogenesis of injury and may be a key to an AKI to CKD transition. Supported by grants from the American Heart Association: (AHA 827257)