Abstract: FR-PO614
Studying the Mechanism of Kidney Resident Macrophage Niche Filling after Temporary Depletion
Session Information
- Cystic Kidney Diseases: Mechanisms and Models
October 25, 2024 | Location: Exhibit Hall, Convention Center
Abstract Time: 10:00 AM - 12:00 PM
Category: Genetic Diseases of the Kidneys
- 1201 Genetic Diseases of the Kidneys: Cystic
Authors
- Yashchenko, Alex, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
- Zimmerman, Kurt, The University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
Background
ADPKD is characterized by large, bilateral fluid-filled cysts scattered throughout the kidney. Our lab and others have previously shown that kidney resident macrophages (KRM) promote cyst progression in mouse models of ADPKD and are histologically cyst-associated. Continuous pharmacological depletion of KRM reduces cystic index and slows disease progression in mice; however, long term depletion of KRM using this approach is not feasible as the depletion is non-specific, affecting resident macrophage populations in multiple tissues. Therefore, we switched our focus to temporary KRM depletion in order to 1) study the mechanism of KRM niche filling, and 2) identify and test factors responsible for engraftment of KRM precursors (monocytes) into an opened KRM niche.
Methods
To study the mechanism of KRM niche filling, we used liposomal clodronate to deplete the KRM niche in Ms4a3Cre-Rosa26TdTomato and Ms4a3Cre-Rosa26TdTomato-Pkd1RC/RC mice. We analyzed the kinetics (i.e. timing) of KRM niche filling, degree of monocyte input into the KRM niche, and intracellular Ki67 staining by flow cytometry. Disease progression was analyzed by H&E staining.
Results
Analysis of preliminary data indicate that the KRM niche in both Ms4a3Cre-Rosa26TdTomato and Ms4a3Cre-Rosa26TdTomato-Pkd1RC/RC mice is repopulated ~12 weeks after depletion due to the recruitment, engraftment, and differentiation of bone marrow-derived monocytes and through self-replication of the remaining kidney resident macrophages. Using single cell RNA sequencing, we identified Cx3cr1 as a gene that was possibly required for the differentiation of monocytes into KRM during post-embryonic niche filling periods. To test the importance of Cx3cr1 expression in monocytes during niche filling, we crossed Lyz2Cre mice to Cx3cr1f/f mice. Analysis of preliminary data from Lyz2Cre-Cx3cr1f/f mice show that CX3CR1 protein expression is significantly reduced in monocytes and KRM compared to controls although KRM was not impacted. Ongoing studies will address the role of monocyte-specific Cx3cr1 in niche filling after depletion in healthy and Pkd1RC/RC mice.
Conclusion
Our data suggest that the open KRM niche is replenished through both monocyte recruitment and engraftment as well as self-proliferation of the remaining KRM. Ongoing studies are addressing the importance of monocyte-specific Cx3cr1 in the process of niche filling.
Funding
- NIDDK Support