Login to Access Video or Poster Abstract: MP12-19
Sources of Funding: UAB Department of Urology, K01DK106284 (TM).

Introduction

Monocytes and macrophages are essential for renal crystal clearance and are recruited into the renal interstitium during this process. Mitochondria are critical for monocyte function during the immune response and oxidative stress cell signaling. Heme oxygenase-1 (HO-1) and manganese superoxide dismutase (MnSOD) are inducible stress response proteins that have been shown to be involved in mitochondrial and anti?inflammatory signaling. We recently demonstrated that monocyte mitochondrial function is decreased in calcium oxalate (CaOx) stone formers when compared to healthy subjects. The objective of this study was to determine whether CaOx crystals alter mitochondrial function, cell viability, and expression of HO-1 and MnSOD in THP-1 cells, a human monocyte derived cell line.

Methods

To test this hypothesis, THP-1 cells were treated with CaOx crystals (0 μg, 50 μg, 100 μg, 200 μg, 500 μg, 1000 μg) for 24 hours prior to measuring mitochondrial function (Seahorse XF96 technology), cell viability (Trypan Blue), and HO-1 and MnSOD expression (Western Blotting). These experiments were repeated in triplicate.

Results

Exposing CaOx crystals to THP-1 cells caused a dose dependent decrease in mitochondrial function and cell viability (p < 0.05). Both HO-1 and MnSOD protein levels were significantly increased in a dose dependent fashion with CaOx crystal treatment (p < 0.05). Furthermore, HO-1 levels were upregulated to a greater extent than MnSOD levels with increased crystal exposure.

Conclusions

In summary, CaOx crystals appear to decrease mitochondrial function and cell viability and induce stress response proteins in THP-1 monocytes. These findings provide potential mechanisms responsible for mitochondrial dysfunction observed in monocytes from CaOx stone formers.

Funding

UAB Department of Urology, K01DK106284 (TM).