Introduction: Notch2 activation via agonistic antibody administration ameliorates podocyte loss and nephrosis in an Adriamycin (ADR)-induced mouse model of glomerular disease. However, the mechanisms by which Notch signaling in podocytes confers protection remain largely unknown. Here, Microarray revealed C-C motif chemokine ligand 5 (CCL5) was the downstream molecule of activated Notch2 in cultured podocytes. While CCL5 is known as a chemoattractant for immune cells, its role in glomerular injury remains controversial. To address, we performed in vitro and in vivo studies to clarify the role of CCL5.

Methods: To investigate the cell-autonomous role of CCL5, we generated CCL5 knockout (KO) cultured podocytes and assessed apoptosis after ADR treatment in vitro. We then generated CCL5 KO mice and induced ADR nephropathy to examine CCL5 function in glomerular injury in vivo. To further distinguish cell-autonomous and non-cell-autonomous effects, bone marrow transplantation was performed between WT and CCL5 KO mice to evaluate the role of CCL5 in podocytes and bone marrow-derived cells. Finally, immunostaining of kidney samples from patients with glomerular disease was conducted to assess CCL5 expression.

Results: In vitro, CCL5 administration protected ADR-treated podocytes, while CCL5 KO exacerbated podocyte injury, indicating a protective cell-autonomous role via an autocrine mechanism. However, in vivo, ADR nephropathy was ameliorated in CCL5 KO mice, suggesting that CCL5 promotes disease progression through non-cell-autonomous mechanisms. Bone marrow transplantation experiments further revealed that WT mice receiving CCL5 KO bone marrow exhibited improved ADR nephropathy, indicating that CCL5 acts on bone marrow-derived cells to exacerbate glomerular damage. Finally, glomerular CCL5 expression was upregulated in patients with glomerular disease, suggesting its involvement in the pathogenesis of human disease.

Conclusion: CCL5 has dual roles in glomerular disease: it protects podocytes through cell-autonomous mechanisms while exacerbating ADR nephropathy by acting on bone marrow-derived cells. These findings highlight CCL5 as a potential therapeutic target for glomerular disease.