gms | German Medical Science

German Congress of Orthopedic and Trauma Surgery (DKOU 2017)

24.10. - 27.10.2017, Berlin

Decreased CD44/ankyrin expression is associated with repressed AKT/eNOS signaling in osteonecrotic bone marrow cells

Meeting Abstract

  • presenting/speaker Ling-Chun Lin - Kaohsiung Chang Gung Memorial Hospital, Chang Gung University, Kaohsiung, Taiwan
  • Tsan-Wen Huang - Chia-Yi Chang Gung Memorial Hospital, Putzu, Chiayi, Taiwan
  • Pei-Hsun Sung - Kaohsiung Chang Gung Memorial Hospital, Chang Gung University, Kaohsiung, Taiwan
  • Chen-Ta Wu - Kaohsiung Chang Gung Memorial Hospital, Chang Gung University, Kaohsiung, Taiwan
  • Hon-Kan Yip - Kaohsiung Chang Gung Memorial Hospital, Chang Gung University, Kaohsiung, Taiwan
  • Mel Lee - Kaohsiung Chang Gung Memorial Hospital, Chang Gung University, Kaohsiung, Taiwan

Deutscher Kongress für Orthopädie und Unfallchirurgie (DKOU 2017). Berlin, 24.-27.10.2017. Düsseldorf: German Medical Science GMS Publishing House; 2017. DocIN11-115

doi: 10.3205/17dkou007, urn:nbn:de:0183-17dkou0072

Published: October 23, 2017

© 2017 Lin et al.
This is an Open Access article distributed under the terms of the Creative Commons Attribution 4.0 License. See license information at http://creativecommons.org/licenses/by/4.0/.


Outline

Text

Objectives: Decreased nitric oxide synthase (NOS) activity has been suggested as the impaired vasodilation and angiogenesis in the osteonecrotic femoral head (ONFH). Single nucleotide polymorphisms (SNP) of the eNOS gene, the T-786C in exon 7 and 27-bp repeat in intron 4, are found in patients with the odds ratio between 2.9 to 6 as compared with controls. However the exact pathogenesis is still enigmatic. Ankyrin is a cytoskeletal protein that interacts with CD44 and promotes Ca2+ dependent NOS activity. We tested our hypothesis in this study that other than the SNP of NOS gene the bone marrow cells from ONFH patients might have aberrant CD44-ankyrin interaction, which in turn causes subnormal activation of eNOS.

Methods: The protocols were IRB approved. Bone marrow cells were harvested from the proximal femur of patients who had been operated with total hip arthroplasties for osteonecrotic hips or intramedullary nailing for femoral fractures. Paraffin sections of femoral heads from osteonecrotic hips or osteoarthritic hips were subjected to immunohistochemical (IHC) staining for the expression of CD44 and ankyrin. Western blotting (WB) were performed to compare the endogenous CD44 and ankyrin expression levels in bone marrow cells. The expression levels of the signal pathway of Akt/eNOS were also analyzed following stimulation of hyaluronic acid.

Results and Conclusion: The endogenous CD44 and ankyrin expression in ONFH tissues and bone marrow cells were decreased as compared with controls. When stimulated with hyaluronic acid, the protein levels of phospho-CD44 (p-CD44), CD44, and ankyrin were increased from 2 hours and sustained until 24 hours in bone marrow cells of the control patients. In contrast, the protein levels of p-CD44, CD44, and ankyrin in bone marrow cells of the osteonecrotic hips treated with hyaluronic acid were relatively lower and delayed in response. Downstream Akt/p-Akt signaling and eNOS expression in bone marrow cells from the osteonecrotic hips were significantly repressed as compared with those responses from the control patients.

This study found the basal protein expression of p-CD44, CD44, and ankyrin were decreased in the femoral heads and bone marrow cells of the ONFH patients. The decreased CD44/ankyrin expression is associated with the repressed Akt/eNOS signal pathway both in its magnitude and its response time. The aberrant CD44/ankyrin/Akt/eNOS signal pathway may play a role in the pathogenesis of ONFH.