• Media type: E-Article
  • Title: Thy-1 deficiency augments bone loss in obesity by affecting bone formation and resorption
  • Contributor: Picke, Ann-Kristin [Author]; Campbell, Graeme Michael [Author]; Schmidt, Felix N. [Author]; Busse, Björn [Author]; Rauner, Martina [Author]; Simon, Jan C. [Author]; Anderegg, Ulf [Author]; Hofbauer, Lorenz C. [Author]; Saalbach, Anja [Author]
  • Corporation: Technische Universität Hamburg ; Technische Universität Hamburg, Institute of Biomechanics
  • Published: 2018
  • Published in: Frontiers in cell and developmental biology ; 6(2018) vom: Okt., Artikel-ID 127, Seite 1-13
  • Language: English
  • DOI: 10.3389/fcell.2018.00127; 10.15480/882.2084
  • Identifier:
  • Keywords: obesity ; Thy-1 ; bone mass ; osteoblast ; osteoclast ; adipocytes ; differentiation ; TNFα
  • Origination:
  • Footnote:
  • Description: Healthy bone remodeling results from a balanced bone formation and bone resorption realized by bone-forming osteoblasts and bone-resorbing osteoclasts, respectively. Recently, Thy-1 (CD90) was identified as positive regulator of osteoblast differentiation and activation, thus, promoting bone formation while concurrently inhibiting adipogenesis and obesity in mice. Additionally, Thy-1 did not affect bone resorption. An obesity-related co-morbidity that is increasing in prevalence is a disturbed bone formation resulting in an increased fracture risk. The underlying mechanisms of obesity-induced bone alterations are not yet fully elucidated and therefore therapy options for efficient bone-anabolic treatments are limited. Therefore, we investigated the impact of Thy-1 on bone metabolism under obese conditions. Indeed, high fat diet (HFD) induced obese mice lacking Thy-1 (Thy-1-/-) showed increased body fat mass compared to wildtype (WT) mice while bone mass (-38%) and formation (-57%) were decreased as shown by micro-computed tomography (μCT) measurement, histological analysis, and fourier-transform infrared spectroscopy (FTIR). Interestingly, under obese conditions, lack of Thy-1 affected both osteoblast and osteoclast function. Number (-30%) and activity of osteoblasts were decreased in obese Thy-1-/- mice while osteoclast number (+39%) and activity were increased. Facilitated bone marrow fat accumulation (+56%) in obese Thy-1-/- mice compared to obese WT mice was associated with upregulated tumor necrosis factor α (Tnfα, +46%) and colony stimulating factor 1 receptor (Csf1r) expression, strong promoters of osteoclast differentiation. Moreover, lack of Thy-1 was accompanied by a reduction of osteoprotegerin (Tnfrsf11b) expression (-36%), an inhibitor of osteoclast differentiation. Altered Tnfα, Csf1r, and Tnfrsf11b expression might be responsible for elevated osteoclast activity in obese Thy-1-deficient mice. In summary, our findings show that lack of Thy-1 promotes obesity under HFD conditions while concurrently decreasing bone mass and formation. Mechanistic studies revealed that under obese conditions lack of Thy-1 impairs both bone formation and bone resorption.
  • Access State: Open Access