Mesenchymal stromal cells-derived secretome rescues cisplatin-induced injury of proximal tubular epithelial cells while dampening macrophage activation in an indirect co-culture system

Background

The interplay between renal proximal tubular epithelial cells (PTEC) and macrophages is important in the progression of kidney injury, caused by a chemotherapeutic drug, cisplatin. Upon injury, PTEC attract macrophages, where macrophages can either promote injury resolution or inflammation. Mesenchymal stromal cells (MSC), having pro-regenerative capacity, might rescue the injury by acting on PTEC and macrophages. We hypothesize MSC can modulate PTEC and macrophage crosstalk upon the injury.

Methods

MSC secretome was harnessed by producing MSC conditioned medium (CM). First, the effect of CM was tested on PTEC and macrophages upon cisplatin injury separately. To evaluate CM and cisplatin effect on PTEC, apoptosis, gene expression and reactive oxygen species of PTEC were assessed. On macrophages, the surface markers for M1 and M2 polarization, and their phagocytosis capacity were measured. Lastly, the interplay between PTEC and macrophages was investigated using an indirect co-culture system. The PTEC injury was evaluated by measuring their apoptosis, nuclei fragmentation, and TNF-α, while macrophage polarization was assessed by phagocytosis assay. The crosstalk of ciPTECs and macrophages was interrogated by LUMINEX assay.

Results

CM rescued cisplatin-induced PTEC death via gene expression modification and oxidative stress amelioration. On macrophages, CM promoted phagocytosis and the expression of M2-associated surface markers CD163 and CD206, while suppressing M1 markers CD86 and HLA-DR. In the co-culture system, CM suppressed PTEC death by inhibiting apoptosis and nuclei fragmentation. CM also downregulated pro-inflammatory response of PTEC, by lowering TNF-α release. While cisplatin inhibited macrophage phagocytosis, PTEC, and CM, to a greater extent, enhanced it. CM dampened macrophage cytokine secretion triggered by PTEC. Of note, despite CM presence, cisplatin caused macrophage death in long-term.

Conclusion

CM rescued cisplatin injury on PTEC and promoted M2 polarization of macrophages, individually. However, combining PTEC and macrophages did not boost CM amelioration of injury on PTEC. We conclude that MSC-CM overrules the fine-orchestrated crosstalk between PTEC and macrophages, at least in vitro.

Offenlegung Interessenkonflikt:

The authors declare no potential conflicts of interest.