This Article Abstract Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in PubMed Alert me to new issues of the journal Add to Saved Citations Download to citation manager Request Permissions Request Reprints Add to My Marked Citations Citing Articles Citing Articles via HighWire Citing Articles via Google Scholar Citing Articles via Scopus Google Scholar Articles by Tan, S.D. Articles by Klein-Nulend, J. Search for Related Content PubMed PubMed Citation Articles by Tan, S.D. Articles by Klein-Nulend, J. Social Bookmarking                         What's this?

Fluid Shear Stress Inhibits TNF-induced Osteocyte Apoptosis

¹ Department of Oral Cell Biology, Academic Centre for Dentistry Amsterdam (ACTA)-Universiteit van Amsterdam and Vrije Universiteit, Van der Boechorststraat 7, NL-1081 BT Amsterdam, The Netherlands; and
² Department of Orthodontics and Oral Biology, Radboud University Nijmegen Medical Centre, Nijmegen, The Netherlands

View larger version (12K): [in this window] [in a new window]   Figure 1. Effects of TNF- induction time (A) and TNF- dose (B) on caspase-3/7 activity in osteoblasts under static conditions. (A) The earliest time point at which apoptosis could be detected was after 16 hrs of 10 ng/mL TNF- treatment. (B) Maximal induction of apoptosis was achieved by 10 ng/mL TNF-. Higher and lower concentrations of TNF- resulted in less induction of apoptosis. Values, obtained from 3 wells of 1 experiment, are expressed as mean ± SEM of TNF--treated-over-control ratios (± TNF- at 10 ng/mL [A]; ± TNF- at 5, 10, 25, 50, 100 ng/mL [B]). Dashed line, ± TNF- = 1 (no effect). *Significant effect of TNF-, p < 0.05.

View larger version (12K): [in this window] [in a new window]   Figure 2. Effect of TNF- on apoptosis in periosteal fibroblasts, osteoblasts, and osteocytes under static conditions. TNF- at 10 ng/mL for 16 hrs increased caspase-3/7 activity in osteocytes and osteoblasts by more than two-fold, but not in periosteal fibroblasts. Values, obtained from 3 (periosteal fibroblast) or 4 (osteoblast and osteocyte) separate experiments, are expressed as mean ± SEM of TNF--treated-over-control ratios (± TNF- at 10 ng/mL). Dashed line, ± TNF- = 1 (no effect). PF, periosteal fibroblasts; OB, osteoblasts; OCY, osteocytes. *Significant effect of TNF- , p < 0.05.

View larger version (16K): [in this window] [in a new window]   Figure 3. Effect of pulsating fluid flow on TNF--induced apoptosis in periosteal fibroblasts, osteoblasts, and osteocytes. Apoptosis was induced by TNF- at 10 ng/mL for 16 hrs. (A) Apoptosis in the absence of L-NAME. One hour of PFF reduced caspase-3/7 activity in TNF--treated osteocytes by 25%, but not in osteoblasts and periosteal fibroblasts. Values obtained from 6 osteoblast, 7 periosteal fibroblast, and 8 osteocyte experiments are expressed as mean ± SEM of PFF-treated-over-control ratios (± PFF). (B) Apoptosis in the presence of L-NAME. Addition of 1 mM L-NAME to the culture medium during exposure to PFF blocked the inhibitory effect of PFF on caspase-3/7 activity in TNF--treated osteocytes, but did not affect apoptosis in osteoblasts and periosteal fibroblasts. Values, obtained from 3 experiments, are expressed as mean ± SEM of PFF-treated-over-control ratios (± PFF). Dashed line, ± PFF = 1 (no effect). PFF, pulsating fluid flow; PF, periosteal fibroblasts; OB, osteoblasts; OCY, osteocytes; L-NAME, NG-Nitro-L-Arginine Methyl Ester. *Significant effect of PFF, p < 0.05.

View larger version (15K): [in this window] [in a new window]   Figure 4. Effect of pulsating fluid flow on NO production by TNF--treated periosteal fibroblasts, osteoblasts, and osteocytes. (A) Cumulative NO production during 30 min of PFF treatment or under static conditions. (B) NO production expressed as PFF-treated-over-control ratios (± PFF) at 10 and 30 min. Application of PFF increased NO production at 30 min in TNF--treated osteocytes, but not in osteoblasts and periosteal fibroblasts. Values are obtained from 4-5 glass slides from 2 experiments (mean ± SEM). Dashed line, ± PFF = 1 (no effect). PFF, pulsating fluid flow; Stat, static cultures; PF, periosteal fibroblasts; OB, osteoblasts; OCY, osteocytes. *Significant effect of PFF, p < 0.05.

Journal of Dental Research, Vol. 85, No. 10, 905-909 (2006)
DOI: 10.1177/154405910608501006


CiteULike    Complore    Connotea    Del.icio.us    Digg    Reddit    Technorati    Twitter    What's this?