Abstract: FR-PO280

VDR Deficiency Induces the Parathyroid Glands Lesions via NFκB Pathway Activation in Uremic Patients

Session Information

Category: Mineral Disease

  • 1202 Mineral Disease: Vitamin D, PTH, FGF-23

Authors

  • Mao, Jianping, Huashan Hosopital, Fudan Univeristy, Shanghai, China
  • Zhang, Minmin, Huashan Hosopital, Fudan Univeristy, Shanghai, China
  • Ni, Li, Huashan Hosopital, Fudan Univeristy, Shanghai, China
  • Wang, Mengjing, Huashan Hosopital, Fudan Univeristy, Shanghai, China
  • Chen, Jing, Huashan Hosopital, Fudan Univeristy, Shanghai, China
Background

Secondary hyperparathyroidism (SHPT) is one of the most common complications in CKD-MBD, but its pathogenesis remains unknown. Recent studies showed that 1,25D suppressed Nuclear Factor-κB (NFκB) activation to suppress tumor hyperplasia. Therefore, whether VDR deficiency induce the tumor-like hyperplasia of parathyroid gland(PTG) via the NFκB pathway activation in uremic patients.

Methods

PTG samples were collected from parathyroidectomy surgery of 10 uremic patients who failed to medical treatment with approval of the Ethics Committee on Human Research at Huashan Hospital. Immunohistochemistry and Western blot detected the expression of VDR, pp65 and PCNA in diffuse and nodular hyperplastic PTG. In vitro, freshly excised PTG tissues were minced into 1mm3 fragments and incubated with 1,25D (0nM, 1nM, 10nM, 100nM, 1000nM) and PDTC (0uM, 2uM, 20uM, 200uM) for 24 hours. ELISA kit measured the levels of iPTH from supernatant. Real-time PCR measured the mRNA levels of preproPTH, PCNA, VDR and IκBα. Western blot measured the protein levels of VDR, p65, pp65 and PCNA.

Results

Compared with diffuse hyperplasia, immunohistochemistry results showed that VDR expression was down-regulated by 34.97% (P<0.01), while pp65 and PCNA were up-regulated by 86.51% (P<0.01) and 97.37% (P<0.01) in nodular hyperplastic glands. Western blot confirmed these above. In vitro, 1,25D up-regulated protein and mRNA levels of VDR by 150.62% (P<0.05) and 35.62% (P<0.05), down-regulated protein level of pp65 by 58.49% (P<0.01), up-regulated mRNA level of IκBα by 72.77% (P<0.01), and down-regulated protein and mRNA levels of PCNA by 42.48% (P<0.05) and 38.49% (P<0.01). These results suggested that 1,25D could activate VDR, inhibit cellular proliferation and inhibit NFκB activation. PDTC did not affect VDR expression, but down-regulated protein level of pp65 by 76.04% (P<0.01), down-regulated protein and mRNA levels of PCNA by 47.39% (P<0.05) and 26.95% (P<0.05). These results suggested that PDTC inhibit NFκB activation and inhibit cellular proliferation, while it had no effect on VDR expression. ELISA results showed that 1,25D and PDTC could both down-regulate iPTH levels by 61.16% (P<0.01) and 49.86% (P<0.05).

Conclusion

Deficiency of VDR and activation of NFκB pathway may be involved in the hyperplasia of PTG in uremic patients, the exact mechanism needs further study.