Differential sensitivity to Wnt-3a and Wnt-5a signaling in primary osteoblasts isolated from hip and knee joints of male and female patients with osteoarthritis — ASN Events
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Differential sensitivity to Wnt-3a and Wnt-5a signaling in primary osteoblasts isolated from hip and knee joints of male and female patients with osteoarthritis (#114)

Leilei Xu 1 , Brya G Matthews 2 3 , Jacob T Munro 4 , Raewyn C Poulsen 1
  1. Department of Pharmacology & Clinical Pharmacology, University of Auckland, Auckland, New Zealand
  2. Department of Biomedical Engineering, University of Connecticut, Farmington, Connecticut, United States of America
  3. Department of Molecular Medicine and Pathology, University of Auckland, Auckland, New Zealand
  4. Department of Surgery, University of Auckland, Auckland, New Zealand

Background: Changes in bone are evident at an early stage of osteoarthritis (OA), yet the role of bone in OA development is poorly understood. Aberrant Wnt signaling in osteoblasts has been implicated as a contributor to OA pathogenesis. Mounting evidence indicates OA pathogenesis and osteoblast phenotype differ between joints and between males and females. The purpose of this study was to compare the response of osteoblasts isolated from OA hip and knee joints of male and female patients to Wnt ligand stimulation.

Methods: Osteoblasts from 35 patients with OA (age 53–87; 15 males/20 females; 20 hips/15 knees) were treated with Wnt3a, Wnt5a (10–200 ng/ml) or vehicle and expression of Wnt-target and osteogenic genes (COL1A1, TCF-4, SOST, LEF-1, RUNX2, OPG, FRZB) assessed by RT-qPCR. Secreted levels of pro-collagen I, osteoprotegerin, and Frizzled-related protein were determined by ELISA. β-catenin, p-JNK1/2, p-CaMKII, sclerostin and RUNX2 levels were measured by western blot.

Results: Secreted pro-collagen I levels were higher following Wnt3a treatment in female hip but not knee osteoblasts. COL1A1 expression was upregulated by high concentrations of Wnt3a in female hip osteoblasts, but downregulated by low concentrations of Wnt3a in female knee osteoblasts. There was no effect of Wnt3a on COL1A1 expression in male hip or knee osteoblasts. Expression of FRZB (endogenous Wnt antagonist) was upregulated following Wnt3a treatment in male hip and female knee but not in female hip osteoblasts. LEF-1 expression was downregulated by Wnt5a treatment in female hip and knee osteoblasts, whereas COL1A1 and OPG expression showed concentration-dependent downregulation following Wnt5a treatment in female knee but not hip osteoblasts. There was no effect of Wnt5a on the expression of any of the genes measured in male osteoblasts.

Conclusions: These results indicate that female osteoblasts exhibit greater sensitivity to Wnts than male osteoblasts. This suggests the role of Wnt signaling in OA is fundamentally distinct across different joints and between males and females.