Mechanism of adipose-derived stem cell-derived extracellular vesicles affecting macrophage efferocytosis by mediating ADAM17/MerTK in the apoptosis of tubular epithelial cells after sepsis-associated acute kidney injury

Abstract

Objective: This study explored the molecular mechanism of adipose-derived stem cell-derived extracellular vesicles (ADSC-EVs) improving post-sepsis-associated acute kidney injury (S-AKI) tubular epithelial cell (TEC) apoptosis by modulating ADAM17/MerTK-mediated macrophage efferocytosis.

Methods: The S-AKI mouse model was established by caecal ligation and puncture and intravenously injected with ADSC-EVs. Mouse kidney macrophages were cultured with LPS, cultured with EVs while transfecting with oe-ADAM17 or si-MerTK, then incubated with Jurkat cells. Mouse serum urea and creatinine, and KIM-1, efferocytosis- and apoptosis-related protein, inflammatory factor, cytokine, and soluble MerTK (sMerTK) levels were determined using colorimetric assay, immunohistochemistry, Western blot, and ELISA. Renal tubular injury, TEC apoptosis, macrophage efferocytosis, and M1/M2 polarization levels were assessed via HE staining, TUNEL staining, immunofluorescence, and flow cytometry, respectively. In vivo validation experiments were conducted.

Results: S-AKI mice displayed elevated levels of serum urea, creatinine, KIM-1, pro-inflammatory factors, pro-apoptotic proteins and ADAM17 protein, decreased anti-apoptotic protein and MerTK protein levels, and diminished M2 polarization. ADSC-EVs down-regulated ADAM17 and sMerTK, and increased cell membrane MerTK, macrophage recognition of apoptotic cells and efferocytosis, and M2 polarization in renal tissues of S-AKI mice and LPS-induced mouse renal macrophages, indicating that ADSC-EVs regulated ADAM17/MerTK-mediated macrophage efferocytosis and promoted M2 polarization. MerTK silencing partially reversed ADSC-EVs-regulated LPS-induced mouse renal macrophage efferocytosis and M2 polarization. In vivo, ADAM17 upregulation partly averted ADSC-EVs-regulated post-S-AKI TEC apoptosis in mouse renal tissues.

Conclusion: ADSC-EVs down-regulated sMerTK level and up-regulated macrophage membrane MerTK protein level by modulating ADAM17 to promote macrophage efferocytosis and ameliorate post-S-AKI TEC apoptosis and inflammation.

Keywords: A disintegrin and metalloprotease protein-17; Adipose-derived stem cell-derived extracellular vesicles; Efferocytosis; Myeloid-epithelial-reproductive tyrosine kinase; Sepsis-associated acute kidney injury.