Related Experiment Video
Updated: Apr 11, 2026
Characterization of Immune Cells and Proinflammatory Mediators in the Pulmonary Environment
Published on: June 24, 2020
Differential Ly6C Expression after Renal Ischemia-Reperfusion Identifies Unique Macrophage Populations
Meghan Clements1, Michael Gershenovich1, Christopher Chaber1
1Tissue Protection and Repair Unit, Renal Science.
Abstract:
Macrophages are a heterogeneous cell type implicated in injury, repair, and fibrosis after AKI, but the macrophage population associated with each phase is unclear. In this study, we used a renal bilateral ischemia-reperfusion injury mouse model to identify unique monocyte/macrophage populations by differential expression of Ly6C in CD11b(+) cells and to define the function of these cells in the pathophysiology of disease on the basis of microarray gene signatures and reduction strategies. Macrophage populations were isolated from kidney homogenates by fluorescence-activated cell sorting for whole genome microarray analysis. The CD11b(+)/Ly6C(high) population associated with the onset of renal injury and increase in proinflammatory cytokines, whereas the CD11b(+)/Ly6C(intermediate) population peaked during kidney repair. The CD11b(+)/Ly6C(low) population emerged with developing renal fibrosis. Principal component and hierarchical cluster analyses identified gene signatures unique to each population. The CD11b(+)/Ly6C(intermediate) population had a distinct phenotype of wound healing, confirmed by results of studies inhibiting the macrophage colony-stimulating factor 1 receptor,whereas the CD11b(+)/Ly6C(low) population had a profibrotic phenotype. All populations, including the CD11b(+)/Ly6C(high) population, carried differential inflammatory signatures. The expression of M2-specific markers was detected in both the CD11b(+)/Ly6C(intermediate) and CD11b(+)/Ly6C(low) populations, suggesting these in vivo populations do not fit into the traditional classifications defined by in vitro systems. Results of this study in a renal ischemia-reperfusion injury model allow phenotype and function to be assigned to CD11b(+)/Ly6C(+) monocyte/macrophage populations in the pathophysiology of disease after AKI.
Insights
Macrophages play key roles in kidney injury, repair, and fibrosis. This study identifies distinct monocyte/macrophage populations (CD11b+/Ly6C high, intermediate, and low) and their specific functions in acute kidney injury (AKI) progression.
Area of Science:
- Immunology
- Nephrology
- Cell Biology
Background:
- Macrophages are crucial in acute kidney injury (AKI), but their specific roles in injury, repair, and fibrosis remain incompletely understood.
- Heterogeneity within macrophage populations complicates defining their precise functions during different phases of AKI.
Purpose of the Study:
- To identify and characterize distinct monocyte/macrophage populations in a mouse model of renal ischemia-reperfusion injury (IRI).
- To elucidate the functional roles of these identified macrophage populations in the pathophysiology of AKI.
Main Methods:
- Utilized a bilateral renal ischemia-reperfusion injury mouse model.
- Employed fluorescence-activated cell sorting (FACS) to isolate CD11b+ cells based on Ly6C expression levels (high, intermediate, low).
- Conducted whole genome microarray analysis to determine gene expression signatures and functional phenotypes of isolated populations.
Main Results:
- Identified three distinct macrophage populations: CD11b+/Ly6C(high) associated with injury onset and inflammation, CD11b+/Ly6C(intermediate) peaking during repair with wound-healing phenotypes, and CD11b+/Ly6C(low) emerging during fibrosis with profibrotic phenotypes.
- Microarray analysis revealed unique gene signatures for each population, differentiating their roles.
- Inhibition of macrophage colony-stimulating factor 1 receptor (M-CSF1R) confirmed the wound-healing phenotype of the CD11b+/Ly6C(intermediate) population.
- Both CD11b+/Ly6C(intermediate) and CD11b+/Ly6C(low) populations expressed M2 markers, challenging traditional in vitro classifications.
Conclusions:
- Phenotype and function can be assigned to specific CD11b+/Ly6C+ monocyte/macrophage populations in AKI pathophysiology.
- The study refines our understanding of macrophage heterogeneity and their dynamic roles in kidney injury, repair, and fibrosis.
- Findings suggest that current in vitro classification systems may not fully capture the complexity of in vivo macrophage phenotypes in AKI.
