OBJECTIVE: To investigate the mechanisms by which chronic tobacco smoking promotes intervertebral disc degeneration (IDD) and vertebral degeneration in mice. METHODS: Three month old C57BL/6 mice were exposed to tobacco smoke by direct inhalation (4 cigarettes/day, 5 days/week for 6 months) to model long-term smoking in humans. Total disc proteoglycan (PG) content [1,9-dimethylmethylene blue (DMMB) assay], aggrecan proteolysis (immunobloting analysis), and cellular senescence (p16INK4a immunohistochemistry) were analyzed. PG and collagen syntheses ((35)S-sulfate and (3)H-proline incorporation, respectively) were measured using disc organotypic culture. Vertebral osteoporosity was measured by micro-computed tomography. RESULTS: Disc PG content of smoke-exposed mice was 63% of unexposed control, while new PG and collagen syntheses were 59% and 41% of those of untreated mice, respectively. Exposure to tobacco smoke dramatically increased metalloproteinase-mediated proteolysis of disc aggrecan within its interglobular domain (IGD). Cellular senescence was elevated two-fold in discs of smoke-exposed mice. Smoke exposure increased vertebral endplate porosity, which closely correlates with IDD in humans. CONCLUSIONS: These findings further support tobacco smoke as a contributor to spinal degeneration. Furthermore, the data provide a novel mechanistic insight, indicating that smoking-induced IDD is a result of both reduced PG synthesis and increased degradation of a key disc extracellular matrix protein, aggrecan. Cleavage of aggrecan IGD is extremely detrimental as this results in the loss of the entire glycosaminoglycan-attachment region of aggrecan, which is vital for attracting water necessary to counteract compressive forces. Our results suggest identification and inhibition of specific metalloproteinases responsible for smoke-induced aggrecanolysis as a potential therapeutic strategy to treat IDD. Published by Elsevier Ltd.
OBJECTIVE: To investigate the mechanisms by which chronic tobacco smoking promotes intervertebral disc degeneration (IDD) and vertebral degeneration in mice. METHODS: Three month old C57BL/6 mice were exposed to tobacco smoke by direct inhalation (4 cigarettes/day, 5 days/week for 6 months) to model long-term smoking in humans. Total disc proteoglycan (PG) content [1,9-dimethylmethylene blue (DMMB) assay], aggrecan proteolysis (immunobloting analysis), and cellular senescence (p16INK4a immunohistochemistry) were analyzed. PG and collagen syntheses ((35)S-sulfate and (3)H-proline incorporation, respectively) were measured using disc organotypic culture. Vertebral osteoporosity was measured by micro-computed tomography. RESULTS: Disc PG content of smoke-exposed mice was 63% of unexposed control, while new PG and collagen syntheses were 59% and 41% of those of untreated mice, respectively. Exposure to tobacco smoke dramatically increased metalloproteinase-mediated proteolysis of disc aggrecan within its interglobular domain (IGD). Cellular senescence was elevated two-fold in discs of smoke-exposed mice. Smoke exposure increased vertebral endplate porosity, which closely correlates with IDD in humans. CONCLUSIONS: These findings further support tobacco smoke as a contributor to spinal degeneration. Furthermore, the data provide a novel mechanistic insight, indicating that smoking-induced IDD is a result of both reduced PG synthesis and increased degradation of a key disc extracellular matrix protein, aggrecan. Cleavage of aggrecan IGD is extremely detrimental as this results in the loss of the entire glycosaminoglycan-attachment region of aggrecan, which is vital for attracting water necessary to counteract compressive forces. Our results suggest identification and inhibition of specific metalloproteinases responsible for smoke-induced aggrecanolysis as a potential therapeutic strategy to treat IDD. Published by Elsevier Ltd.
Authors: E Viikari-Juntura; R Martikainen; R Luukkonen; P Mutanen; E P Takala; H Riihimäki Journal: Occup Environ Med Date: 2001-05 Impact factor: 4.402
Authors: A Izzotti; M Bagnasco; F D'Agostini; C Cartiglia; R A Lubet; G J Kelloff; S De Flora Journal: Carcinogenesis Date: 1999-08 Impact factor: 4.944
Authors: Guus G H van den Akker; Lars M T Eijssen; Stephen M Richardson; Lodewijk W van Rhijn; Judith A Hoyland; Tim J M Welting; Jan Willem Voncken Journal: Cartilage Date: 2018-04-09 Impact factor: 4.634
Authors: Pedro H I Pohl; Thomas P Lozito; Thais Cuperman; Takashi Yurube; Hong J Moon; Kevin Ngo; Rocky S Tuan; Claudette St Croix; Gwendolyn A Sowa; Luciano M R Rodrigues; James D Kang; Nam V Vo Journal: J Orthop Res Date: 2016-06-14 Impact factor: 3.494
Authors: Kevin Ngo; Prashanti Patil; Sara J McGowan; Laura J Niedernhofer; Paul D Robbins; James Kang; Gwendolyn Sowa; Nam Vo Journal: Mech Ageing Dev Date: 2017-08-19 Impact factor: 5.432
Authors: Nam V Vo; Robert A Hartman; Prashanti R Patil; Makarand V Risbud; Dimitris Kletsas; James C Iatridis; Judith A Hoyland; Christine L Le Maitre; Gwendolyn A Sowa; James D Kang Journal: J Orthop Res Date: 2016-08-12 Impact factor: 3.494
Authors: Luigi A Nasto; Kevin Ngo; Adriana S Leme; Andria R Robinson; Qing Dong; Peter Roughley; Arvydas Usas; Gwendolyn A Sowa; Enrico Pola; James Kang; Laura J Niedernhofer; Steven Shapiro; Nam V Vo Journal: Spine J Date: 2013-11-06 Impact factor: 4.166