Kidney Week

Abstract: TH-PO270

Orai1 Mediated Ca+2 Signaling Influences IL-17 Expression in CD4+ T Cells Following I/R

Session Information

• AKI Basic: Inflammation and Transcription
  November 02, 2017 | Location: Hall H, Morial Convention Center
  Abstract Time: 10:00 AM - 10:00 AM

Category: Acute Kidney Injury

• 001 AKI: Basic

Authors

• Mehrotra, Purvi, Indiana School of Medicine, Indianapolis, Indiana, United States

Purvi Mehrotra,

• Basile, David P., Indiana University School of Medicine, Indianapolis, Indiana, United States

David P. Basile,

Background

T-helper 17 (Th17) cells have been implicated in the pathogenesis of acute kidney Injury (AKI). Renal Th17 cells transiently increase for up to 3-days post ischemia/reperfusion (I/R) and return to basal levels within a week. Exposure of post AKI rats to elevated dietary salt (4%) stimulates sustained induction of renal Th17 cells, which is associated with CKD progression. The store-operated calcium channel (SOCC), Orai-1 plays a role in models of inflammatory disease such as colitis or autoimmune encephalopathy, which may be influenced by dietary salt. We hypothesized that AKI primes CD4+ T cells to increase IL17 expression secondary to Orai1 dependent Ca²⁺ signaling.

Methods

FACs analysis demonstrated increased Orai1 protein in renal CD4+ T-cells 7 days following I/R (MFI:221644±3567) relative to sham operated controls (MFI:106924±467; p<0.05). To evaluate the role of Orai1 mediated Ca²⁺ influx in the progression of AKI, rats were subjected to bilateral I/R and the dependency of AKI primed T cells on Ca²⁺ entry was evaluated using an in vitro assay of renal CD4+ cells, which resulted in ~5 fold increase in IL17 expression in response to Ang II (10^-7M) and elevated extracellular Na⁺ (170 mM).

Results

The IL17 induction of AKI primed CD4+ cells in vitro was attenuated by > 95% (p<0.05) by 3 inhibitors that target Orai-1 (2-ABP (20mm), AnCoA4 (50mm) or YM58483 (120nm)). A significant percentage (40-50%) of AKI-primed CD4+ cells, but not sham-derived CD4 cells, manifested increased intracellular Ca²⁺ in response AngII+170 mM Na⁺, a response that was completely abrogated by co-incubation with AnCoA4. Furthermore, treatment with YM58483 in vivo (1mg/Kg), reduced renal Th17 cells 2 days post I/R compared to vehicle treated rats (15,3076±1265 vs 7390±439 cells/gram of kidney; p<0.05). Interestingly, YM58483 had no effect on renal Th1 or Th2 cells. In addition, YM58483 significantly reduced the extent of renal injury by attenuating the increase in serum creatinine by ~66% (p<0.05) vs vehicle treated post AKI rats.

Conclusion

Taken together, these data suggest that I/R leads to increased Orai-1 mediated Ca²⁺ influx thereby enhancing IL-17 expression and may influence the severity of AKI.

Funding

• NIDDK Support