Introduction: The role of the mammalian/mechanistic target of rapamycin (mTOR) in the pathophysiology of renal ischemia-reperfusion injury (IRI) is poorly characterized; furthermore, the influence of dendritic cell (DC)-based alterations in mTOR signaling in IRI has not been investigated.

Methods: We evaluated activation of the mTORC1/2 pathway in sham-operated and post kidney IRI C57BL/6 mice. Ex vivo isolated bone marrow-derived mTORC2 deficient (Rictor^-/-) or wild-type (WT) DC underwent hypoxia-reoxygenation and then were analysed by flow cytometry. Adoptive transfer of WT or Rictor^-/- DC to C57BL/6 mice followed by unilateral renal IRI was used to assess their in vivo migratory capacity. Age- and gender-matched DC-specific Rictor^-/- mice or littermate controls underwent bilateral renal IRI followed by assessment of renal function, renal DC metabolism, histopathology, and bio-molecular and cell infiltration analysis.

Results: Protein expression of phosphorylated S6K that is a downstream of mTORC1 was upregulated, but conversely, phosphorylated AktS473 that is a downstream of mTORC2 was decreased in whole kidney tissue in response to IRI. Rictor^-/- DC expressed more CD80/CD86 but less programed death ligand-1 (PDL1) which was enhanced by hypoxia-reoxygenation, and also increased migration to the injured kidney. Following IRI, Rictor^-/- DC mice developed higher serum creatinine, more severe histologic damage, and greater pro-inflammatory mRNA transcript profiles of IL-1β, IL-6 and TNF-α compared to littermate controls. After IRI challenge, Rictor^-/- DC showed increased TNF-α production, but significantly reduced IL-10 secretion compared to WT DC. Renal Rictor-/- DC were glycolytically biased compared to WT DC under both basal and IRI conditions. A greater influx of both neutrophils and T cells was seen in Rictor^-/- DC mice, in addition to CD11c⁺MHCII⁺CD11b^hiF4/80⁺ renal DC, that expressed more CD86 but less PDL1.

Conclusions: These novel data suggest that mTORC2 signaling in renal DC negatively regulates acute kidney injury. Thus, DC-targeted elimination of Rictor enhances inflammatory and migratory responses to the injured kidney, highlighting the regulatory roles of both DC and Rictor in the pathophysiology of renal IRI.

CITATION INFORMATION: Dai H., Watson A., Fantus D., Peng L., Thomson A., Rogers N. mTORC2 Deficiency in CD11c⁺ dendritic Cells Promotes Acute Kidney Injury Am J Transplant. 2017;17 (suppl 3).

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