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Updated: May 30, 2026
Phenotypic Characterization of Macrophages from Rat Kidney by Flow Cytometry
Published on: October 18, 2016
Renal microenvironments and macrophage phenotypes determine progression or resolution of renal inflammation and
1Department of Nephrology, Medizinische Poliklinik der LMU, University of Munich, Munich, Germany.
Abstract:
Chronic kidney disease involves renal inflammation, interstitial fibrosis, and tubular and vascular atrophy. Macrophages seem to foster all of these histomorphological abnormalities, but their specific contributions remain controversial. Recruited monocytes differentiate into different tissue macrophage phenotypes, but current classifications are largely based on in vitro studies that do not adequately mirror tissue environments in vivo. To overcome this limitation, we propose to classify tissue macrophages according to their predominant roles in the phases of wound healing tissue environments, that is, inflammation, epithelial healing, mesenchymal healing, and fibrolysis. In this review, we discuss the evidence on respective macrophage phenotypes in renal pathology. This view sheds light on several aspects of renal remodeling in kidney disease: (1) renal infection or cell necrosis induces proinflammatory 'M1' macrophages that exacerbate renal cell damage, (2) uptake of apoptotic cells induces anti-inflammatory 'M2c/suppressor' macrophages that promote epithelial and vascular repair, (3) insufficient vascular and epithelial healing despite abundant growth factor secretion promotes profibrotic 'M2a/wound healing' macrophages that accelerate fibrogenesis, and (4) theoretically, fibrolytic macrophages should exist and await investigation.
Insights
This review proposes a new way to classify macrophages in chronic kidney disease based on their role in wound healing. This approach clarifies macrophage contributions to renal inflammation, fibrosis, and repair.
Area of Science:
- Nephrology
- Immunology
- Pathology
Background:
- Chronic kidney disease (CKD) is characterized by renal inflammation, fibrosis, and atrophy.
- Macrophages are implicated in CKD pathogenesis, but their specific roles are debated.
- Current macrophage classification relies on in vitro studies, not fully reflecting in vivo tissue environments.
Purpose of the Study:
- To propose a novel classification system for tissue macrophages in CKD.
- To categorize macrophages based on their roles in distinct wound healing phases: inflammation, epithelial healing, mesenchymal healing, and fibrolysis.
- To review existing evidence on macrophage phenotypes in renal pathology.
Main Methods:
- Literature review and synthesis of evidence on macrophage phenotypes in renal pathology.
- Application of a wound-healing framework to classify macrophage roles in CKD.
- Discussion of macrophage contributions to renal remodeling.
Main Results:
- Pro-inflammatory 'M1' macrophages exacerbate renal cell damage following infection or necrosis.
- 'M2c/suppressor' macrophages promote epithelial and vascular repair through apoptotic cell uptake.
- 'M2a/wound healing' macrophages accelerate fibrogenesis when healing is impaired.
Conclusions:
- A wound-healing-based classification offers new insights into macrophage functions in CKD.
- Understanding these distinct macrophage roles is crucial for targeting therapeutic interventions.
- Further investigation into fibrolytic macrophages is warranted.
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