Nanobacteria induces crystal adhesion and activates the CaSR-Claudin-14 signaling pathway in HK-2 cells

Heng Yang^1,2, Qinzhang Wang¹, Zhiqiang Hao^1,2, Jingshen Wang^1,2, Yuan Wang^1,2, Yongle Li^1,2, Minghui Tan^1,2, Biao Qian^1,2

¹Department of Urological Surgery, the First Affiliated Hospital of the Medical College of Shihezi University, Shihezi 832000, Xinjiang, China - ²Department of Urology, First Affiliated Hospital of Gannan Medical University; Institute of Urology, Gannan Medical University, Ganzhou, Jiangxi, 341000, China

Purpose: The infection of nanobacteria (NB) and dysregulation of calcium homeostasis is critical for the formation of kidney stones. However, the relationship between the infection of NB and the calcium metabolism in the process of the formation of stones remains unclear. Therefore, the aim of this study was to investigate the impact of the infection of NB on the crystal retention and expression of calcium-sensing receptor (CaSR) and Claudin-14 in HK-2 cells.

Methods: NB were isolated from the urine of patients who were clinically diagnosed with kidney stones. Three groups were established: control group, NB group and Calcium oxalate monohydrate (COM) group. After incubated for 6h, 12h and 24h respectively, the crystal adhesion and the expression level of CaSR and Claudin-14 were observed.

Results: The laser scanning confocal fluorescence microscope showed that the number of crystals adhering in NB and COM groups were significantly higher than that in control group, and increased with the incubation time expanding. At different time points, the relatively mRNA and protein expression levels of CaSR and Claudin-14 in NB group were significantly higher than those in control group (P<0.001).

Conclusions: NB causes the crystals adhesion and upregulates the mRNA and protein expression levels of CaSR-Claudin-14 in HK-2 cells.