Effects of long-term cigarette smoke exposure on bone metabolism, structure, and quality in a mouse model of emphysema

Smoking is a common risk factor for both chronic obstructive pulmonary disease (COPD) and osteoporosis. In patients with COPD, severe emphysema is a risk factor for vertebral fracture; however, the effects of smoking or emphysema on bone health remain largely unknown. We report bone deterioration in a mouse model of emphysema induced by nose-only cigarette smoke (CS) exposure. Unexpectedly, short-term exposure for 4-weeks decreased bone turnover and increased bone volume in mice. However, prolonged exposure for 20- and 40-weeks reversed the effects from suppression to promotion of bone resorption. This long-term CS exposure increased osteoclast number and impaired bone growth, while it increased bone volume. Strikingly, long-term CS exposure deteriorated bone quality of the lumbar vertebrae as illustrated by disorientation of collagen fibers and the biological apatite c-axis. This animal model may provide a better understanding of the mechanisms underlying the deterioration of bone quality in pulmonary emphysema caused by smoking.Effects of long-term cigarette smoke exposure on bone metabolism, structure, and quality in a mouse model of emphysema. Mamoru Sasaki et al. PLOS ONE. 2018. 1(30) doi.org/10.1371/journal.pone.019161

Clinical utility of blood neutrophil-lymphocyte ratio in Japanese COPD patients

Abstract Background Neutrophil-to-lymphocyte ratio (NLR) is a biomarker of inflammation in chronic obstructive pulmonary disease (COPD) patients. But, a meaningful threshold and the longitudinal changes are unknown. We aimed to investigate the association between NLR and the clinical characteristics of COPD patients and to determine a meaningful threshold and the longitudinal changes for NLR. Methods Keio University and its affiliate hospitals conducted an observational COPD cohort study over 3 years. We performed a blood examination and a pulmonary function test. Blood examination was completed at baseline and annually thereafter, at a time when the disease was stable. Two hundred seventy-four patients who had at least 3 blood examinations over 3 years were included. Results Baseline NLR was correlated with baseline C-reactive protein (CRP) (r = 0.18, p = 0.003) and SAA (r = 0.34, p <  0.001). We defined an NLR score of 2.7 as the arbitrary cut-off value based on upper quartile points. COPD patients with NLR ≥ 2.7 were older (p = 0.037), had a lower BMI (p = 0.005) and a lower %FEV1 (p = 0.0003) compared to patients with NLR < 2.7. Receiver-operating-characteristic (ROC) curves showed the optimal cutoff for the baseline NLR in the predicting moderate/severe exacerbation to be 2.7, which was same as the upper quartile points. Follow-up analysis over 3 years revealed that the differences in the trends of NLR among the three groups based on the categories of exacerbations (moderate or severe, mild, no exacerbation) were significant (p = 0.006). Conclusions NLR is associated with COPD severity and exacerbations. For predicting exacerbations, we estimated the threshold of NLR to be 2.7 at baseline. Trial registration Clinical trial registered with the University Hospital Medication Information Network (UMIN000003470, April 10, 2010)

Effects of long-term cigarette smoke exposure on bone metabolism, structure, and quality in a mouse model of emphysema

<div><p>Smoking is a common risk factor for both chronic obstructive pulmonary disease (COPD) and osteoporosis. In patients with COPD, severe emphysema is a risk factor for vertebral fracture; however, the effects of smoking or emphysema on bone health remain largely unknown. We report bone deterioration in a mouse model of emphysema induced by nose-only cigarette smoke (CS) exposure. Unexpectedly, short-term exposure for 4-weeks decreased bone turnover and increased bone volume in mice. However, prolonged exposure for 20- and 40-weeks reversed the effects from suppression to promotion of bone resorption. This long-term CS exposure increased osteoclast number and impaired bone growth, while it increased bone volume. Strikingly, long-term CS exposure deteriorated bone quality of the lumbar vertebrae as illustrated by disorientation of collagen fibers and the biological apatite c-axis. This animal model may provide a better understanding of the mechanisms underlying the deterioration of bone quality in pulmonary emphysema caused by smoking.</p></div

Effects of long-term CS exposure on collagen orientation and biological apatite c-axis alignment of vertebral bodies.

<p>(A) Schematic presentation of bone histological indices (H&E staining, polarization, collagen orientation and biological apatite <i>c</i>-axis alignment). (B) Representative polarizing microscope images in the fourth vertebral bodies (longitudinal section) of B6-female mice after 20 and 40 weeks of air- or CS exposure. Scale bars = 100 μm. (C) Intensity ratio of (002/310) as biological apatite c-axis alignment. The data are shown as means ± SDs. *P<0.05 between air-exposed controls (open bars: <i>n</i> = 10 at 20 weeks, <i>n</i> = 5 at 40 weeks) and CS-exposed B6-female mice (closed bars: <i>n</i> = 5 at 20 weeks, <i>n</i> = 12 at 40 weeks). Statistical analysis was performed with Student’s <i>t</i>-test.</p

Changes in body weight, bone turnover, and bone structure after short-term CS exposure in mice with and without ovariectomy.

<p>(A) Longitudinal changes in body weight of C57BL/6J female (B6-female) mice over 4 weeks of air-exposure (open triangle, <i>n</i> = 10) or CS-exposure (closed, <i>n</i> = 9), and ovariectomized (B6-OVX) mice, of air-exposure (open square, <i>n</i> = 9) or CS-exposure (closed, <i>n</i> = 9). The body weight data are shown as means ± SDs. (B, C) Bone metabolism markers (urinary DPD and serum osteocalcin) after 4 weeks of air- (open bar) and CS exposure (closed bar). (D) Representative micro-CT 3D images of fourth vertebral body sections created by longitudinal cutting (left-oblique view). Scale bars = 1 mm. (E–H) micro CT bone structure analyses (BV/TV, Tb.N, Tb.Th and Tb.Sp) after 4 weeks of air- (open bar) and CS exposure (closed bar). The data are shown as means ± SDs. *P<0.05 between air- and CS-exposed mice. Statistical analyses were performed with Student’s <i>t</i>-test.</p

Changes of body weight, abdominal fat volume, and bone metabolism markers upon long-term CS exposure.

<p>(A) Longitudinal changes in body weight of air- exposed (open triangle: <i>n</i> = 5) and CS-exposed mice (closed triangle: <i>n</i> = 10 at the start, <i>n</i> = 9 at the end). The body weight data are shown as means ± SDs. *P<0.05 between air-exposed controls and CS-exposed B6-female mice. Statistical analysis was performed with Student’s <i>t</i>-test at each time point. (B) Representative micro-CT images (transverse view) of abdominal fat after 4 weeks of CS exposure distinguishing between visceral fat (yellow) and subcutaneous fat (orange). Abdominal visceral fat volume at 0, 4, 20, and 40 weeks of CS exposure. (C, D) Bone metabolism markers (urinary DPD and serum osteocalcin) at 4, 20, and 40 weeks of CS exposure. The data are shown as means ± SDs. *P<0.05 between air-exposed controls (open bars: <i>n</i> = 10 at 4 weeks, <i>n</i> = 10 at 20 weeks, <i>n</i> = 5 at 40 weeks) and CS-exposed B6-female mice (closed bars: <i>n</i> = 9 at 4 week, <i>n</i> = 5 at 20 weeks, <i>n</i> = 9 at 40 weeks). Statistical analysis was performed with Student’s <i>t</i>-test.</p

Effects of CS exposure on osteoclasts and osteoblasts of vertebra.

<p>(A) Representative H&E staining of the fourth vertebral body (longitudinal section) at 40 weeks in CS- and air-exposed mice. Representative osteoblasts (arrows) and osteoclasts (arrowheads) in the boxed areas are shown on the right at a higher magnification. Scale bars at low-power and high-power magnification are 500 and 50 μm, respectively. (B, C) Osteoclast surface/bone surface (Oc.S/BS) and osteoblast surface/bone surface (Ob.S/BS) after 4, 20, and 40 weeks of CS exposure. The data are shown as means ± SDs. *P<0.05 between air-exposed controls (open bars: <i>n</i> = 10 at 4 weeks, <i>n</i> = 10 at 20 weeks, <i>n</i> = 5 at 40 weeks) and CS-exposed B6-female mice (closed bars: <i>n</i> = 9 at 4 week, <i>n</i> = 5 at 20 weeks, <i>n</i> = 9 at 40 weeks). Statistical analysis was performed with Student’s <i>t</i>-test.</p

Effects of long-term CS exposure on lung, fat and bone.

<p>The association of deteriorating bone quality with low fat mass and presence of emphysema indicates that the underlying mechanisms link the lung to the skeletal system; however, whether this is a direct effect of long-term CS exposure or a secondary effect of pulmonary and extra-pulmonary changes remains unclear. Representative lung sections stained with H&E after 40 weeks of CS exposure (scale bars = 100 μm). Representative micro-CT images (transverse view) of abdominal fat after 40 weeks of CS exposure distinguishing between visceral fat (yellow) and subcutaneous fat (orange). Representative micro-CT 3D (scale bars = 1 mm) and polarizing microscope images (scale bars = 100 μm) of fourth vertebral body after 40 weeks CS exposure.</p