Type 2 Conventional Dendritic Cells Drive Necroinflammation in Postischemic Acute Kidney Injury and Disease

Background: Ischemia-reperfusion injury (IRI) is a frequent cause of acute kidney injury and disease (AKI/AKD), which can lead to acute tubular necrosis and irreversible loss of kidney function. Kidney-resident conventional dendritic cells (cDCs) contribute to all phases of AKI but separate into several functional subsets. Type 1 conventional dendritic cells (cDC1s) have renoprotective effects, as their deficiency exacerbates inflammation and injury in the IRI-induced AKI/AKD model. We hypothesized that type 2 conventional dendritic cells (cDC2s) may have an opposite role in AKI. Methods: We performed unilateral IRI (uIRI) surgery in mice that lack interferon regulatory factor 4 (IRF4) in DC lineage Clec9a-positive cells (Clec9a-cre; IRF4fl/fl) and wild-type mice. Single-cell suspensions were isolated from injured kidneys and analysed by flow cytometry to detect kidney mononuclear phagocytes. In vitro we generated bone marrow derived CD103+ dendritic cells by FLT3 ligand-rich supernatant and GM-CSF. We generated bone marrow-derived DCs from wild-type mice and Clec9a-cre; IRF8fl/fl mice to obtain cDC1-like and cDC2-like cells. Results: IRF4 deletion on DC lineage cells reduced the kidney-resident population of cDC2s without affecting resident cDC1s compared to control mice. Clec9a-cre; IRF4fl/fl-mice showed at day 1 and 5 of uIRI reduced tubular cell injury, improved kidney function, and recovery. This was associated with elevated expression of anti-inflammatory cytokines, decreased pro-inflammatory cytokines, neutrophil chemoattractant expression (CXCL-2), recruitment of neutrophils, and differentiation of Th2 and Th17 cells, leading to reduced acute tubular cell death. In addition, bone marrow-derived DCs from wild-type mice and Clec9a-cre; IRF8fl/fl mice were separately induced and differentiated into cDC1-like and cDC2-like cells, then stimulated with LPS in vitro. cDC2-like cells exhibited a higher proinflammatory cytokine secretion profile, with increased levels of CXCL-2 compared to cDC1-like cells, consistent with the in vivo findings. Conclusion: Together, cDC2s have an immunoregulatory role in AKI/AKD and could serve as a potential therapeutic target for improving kidney injury and inflammation during AKI. Funding: Government Support – Non-U.S.