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 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 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 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

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

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

Effects of CS exposure on bone structure on micro-CT and mechanical strength tests of vertebral bodies.

<p>(A) At 4, 20, and 40 weeks of CS exposure, representative micro-CT 3D images of fourth vertebral body sections created by longitudinal cutting (left-oblique view). Scale bars = 1 mm. (B–D) Vertebral body height, cortical cross sectional area, and bone volume to tissue volume ratio (BV/TV). *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 mice (closed bars: <i>n</i> = 9 at 4 week, <i>n</i> = 5 at 20 weeks, <i>n</i> = 9 at 40 weeks). (E–G) Stiffness, ultimate load and energy-to-failure of fifth and sixth lumbar vertebral bodies. The data are shown as means ± SDs. *P<0.05, ☨P = 0.07 between air-exposed controls (open bars, L5: <i>n</i> = 5, L6: <i>n</i> = 5) and CS-exposed mice (closed bars, L5: <i>n</i> = 9, L6: <i>n</i> = 9). The data are shown as means ± SDs. Statistical analysis was performed with Student’s <i>t</i>-test.</p

Additional file 1 of Clinical utilization of artificial intelligence-based COVID-19 pneumonia quantification using chest computed tomography – a multicenter retrospective cohort study in Japan

Supplementary Material