Naofumi Kameyama

Evaluation of cigarette smoke-induced emphysema in mice using quantitative micro-computed tomography

Chronic cigarette smoke (CS) exposure provokes variable changes in the lungs, and emphysema is an important feature of chronic obstructive pulmonary disease. The usefulness of micro-computed tomography (CT) to assess emphysema in different mouse models has been investigated, but few studies evaluated the dynamic structural changes in a CS-induced emphysema mouse model. A novel micro-CT technique with respiratory and cardiac gating has resulted in high-quality images that enable processing for further quantitative and qualitative analyses. Adult female C57BL/6J mice were repeatedly exposed to mainstream CS, and micro-CT scans were performed at 0, 4, 12, and 20 wk. Emphysema was also histologically quantified at each time point. Air-exposed mice and mice treated with intratracheal elastase served as controls and comparisons, respectively. End-expiratory lung volume, corresponding to functional residual volume, was defined as the calculated volume at the phase of end-expiration, and it evaluated air trapping. The end-expiratory lung volumes of CS-exposed mice were significantly larger than those of air controls at 12 and 20 wk, which was in line with alveolar enlargement and destruction by histological quantification. However, CS exposure neither increased low attenuation volume nor decreased the average lung CT value at any time point, unlike the elastase-instilled emphysema model. CS-exposed mice had rather higher average lung CT values at 4 and 12 wk. This is the first study characterizing a CS-induced emphysema model on micro-CT over time in mice. Moreover, these findings extend our understanding of the distinct pathophysiology of CS-induced emphysema in mice.

Pneumococcal Infection Aggravates Elastase-Induced Emphysema via Matrix Metalloproteinase 12 Overexpression

BACKGROUND Acute exacerbation of chronic obstructive pulmonary disease (COPD)--typically caused by bacterial or viral infection--is associated with poor prognosis and emphysema progression through unknown mechanisms. We aimed to elucidate the mechanisms responsible for the poor prognosis and emphysema progression associated with COPD exacerbation. METHODS We established a mouse model mimicking acute human COPD exacerbation, wherein mice with elastase-induced emphysema were intranasally infected with Streptococcus pneumoniae. RESULTS In mice with elastase-induced emphysema, infection with S. pneumoniae resulted in increased mortality, an increased number of inflammatory cells in bronchoalveolar lavage fluid (BALF), and increased matrix metalloproteinase 12 (MMP-12) production in the lungs, as well as enhanced emphysema progression. The increased MMP-12 production was mostly due to alveolar type II cells, alveolar macrophages, and lymphocytes that aggregated around vessels and bronchioles. Dexamethasone treatment suppressed the mortality rate and number of inflammatory cells in BALF but not emphysema progression, possibly owing to the failure of MMP-12 suppression in the lungs, whereas treatment with the MMP inhibitor ONO-4817 dramatically suppressed both mortality rate and emphysema progression. CONCLUSIONS These results suggest that MMP-12 production during COPD exacerbation results in increased mortality and emphysema progression. Our study identifies MMP-12 as a target to prevent further aggravation of COPD.

Impact of mild exacerbation on COPD symptoms in a Japanese cohort

Background Patients with COPD might not report mild exacerbation. The frequency, risk factors, and impact of mild exacerbation on COPD status are unknown. Objectives The present study was performed to compare features between mild exacerbation and moderate or severe exacerbation in Japanese patients with COPD. Patients and methods An observational COPD cohort was designed at Keio University and affiliated hospitals to prospectively investigate the management of COPD comorbidities. This study analyzes data only from patients with COPD who had completed annual examinations and questionnaires over a period of 2 years (n=311). Results Among 59 patients with mild exacerbations during the first year, 32.2% also experienced only mild exacerbations in the second year. Among 60 patients with moderate or severe exacerbations during the first year, 40% also had the same severity of exacerbation during the second year. Findings of the COPD assessment test and the symptom component of the St George’s Respiratory Questionnaire at steady state were worse in patients with mild exacerbations than in those who were exacerbation free during the 2-year study period, although the severity of the ratio of predicted forced expiratory volume in 1 second did not differ between them. Severe airflow limitation (the ratio of predicted forced expiratory volume in 1 second <50%) and experience of mild exacerbations independently advanced the likelihood of an elevated COPD assessment test score to ≥2 per year. Conclusion The severity of COPD exacerbation seemed to be temporally stable over 2 years, and even mild exacerbations adversely impacted the health-related quality of life of patients with COPD.

Intermittent Exposure to Cigarette Smoke Increases Lung Tumors and the Severity of Emphysema More than Continuous Exposure

&NA; Lung cancer and chronic obstructive pulmonary disease are leading causes of morbidity and mortality worldwide, and cigarette smoking is a main risk factor for both. The presence of emphysema, an irreversible lung disease, further raises the risk of lung cancer in patients with chronic obstructive pulmonary disease. The mechanisms involved in smoke‐induced tumorigenesis and emphysema are not fully understood, attributable to a lack of appropriate animal models. Here, we optimized a model of cigarette smoke (CS)‐induced lung cancer and emphysema in A/J mice treated with 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone, a potent carcinogen. We investigated whether variations in CS exposure patterns with the same total amount and duration of exposure affect tumorigenesis and/or development of emphysema. Continuous CS exposure for 3 months significantly suppressed 4‐(methylnitrosamino)‐1‐(3‐pyridyl)‐1‐butanone‐induced development of adenomas and adenocarcinomas; however, emphysema independently developed during this period. Surprisingly, intermittent CS exposure increased the severity of emphysema and resulted in a higher incidence of adenocarcinomas. Furthermore, intermittent CS exposure elicited a marked increase in M2‐polarized macrophages within and near the developed tumors. By employing a CS exposure protocol with repeated cycles of cessation and relapse, we provide evidence that intermittent CS exposure enhances tumorigenesis and emphysema progression more than that of continuous CS exposure.

Using Micro-computed Tomography for the Assessment of Tumor Development and Follow-up of Response to Treatment in a Mouse Model of Lung Cancer.

Lung cancer is the most lethal cancer in the world. Intensive research is ongoing worldwide to identify new therapies for lung cancer. Several mouse models of lung cancer are being used to study the mechanism of cancer development and to experiment with various therapeutic strategies. However, the absence of a real-time technique to identify the development of tumor nodules in mice lungs and to monitor the changes in their size in response to various experimental and therapeutic interventions hampers the ability to obtain an accurate description of the course of the disease and its timely response to treatments. In this study, a method using a micro-computed tomography (CT) scanner for the detection of the development of lung tumors in a mouse model of lung adenocarcinoma is described. Next, we show that monthly follow-up with micro-CT can identify dynamic changes in the lung tumor, such as the appearance of additional nodules, increase in the size of previously detected nodules, and decrease in the size or complete resolution of nodules in response to treatment. Finally, the accuracy of this real-time assessment method was confirmed with end-point histological quantification. This technique paves the way for planning and conducting more complex experiments on lung cancer animal models, and it enables us to better understand the mechanisms of carcinogenesis and the effects of different treatment modalities while saving time and resources.

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.

Impact of cataract on health-related quality of life in a longitudinal Japanese chronic obstructive pulmonary cohort:

Cigarette smoking increases the risk of developing both cataract and chronic obstructive pulmonary disease (COPD). The prevalence of cataract and the clinical characteristics of COPD patients with cataract were retrospectively investigated in a 2-year observational COPD cohort. We analyzed 395 patients with complete data on ophthalmologic evaluation (319 subjects with COPD and 76 subjects at risk of COPD). There was no difference in the prevalence of cataract between COPD patients and those at risk (47.0% vs. 42.1%, p = 0.44). Age ≥ 75 years, low body mass index, and hypertension were independently associated with cataract as a comorbidity in COPD. The incidence of exacerbation within 2 years was significantly higher in COPD patients with cataract than those without cataract (36.6% vs. 18.3%, p = 0.0019). COPD patients with cataract exhibited significantly higher COPD assessment test score compared to those without cataract (13.7 ± 8.9 vs. 11.5 ± 7.2, p = 0.0240). Overall St George’s Respiratory Questionnaire score and each component were significantly worse in COPD patients with cataract compared to those without cataract. COPD patients with cataract exhibited poor health-related quality of life and frequent exacerbations. The association between cataract and exacerbations of COPD deserves further attention.

Radiologic features of precancerous areas of the lungs in chronic obstructive pulmonary disease

Background Only a few studies have evaluated the radiologic features of pre-existing structural abnormalities where lung cancer may develop. This study aimed to analyze the computed tomography (CT) images of lung areas where new cancer developed in chronic obstructive pulmonary disease (COPD) patients. Patients and methods We conducted a multicenter, longitudinal cohort study, called the Keio COPD Comorbidity Research, to assess the incidence of lung cancer. Emphysema and interstitial abnormalities were evaluated in 240 COPD patients who had baseline CT scans applicable for further digital analyses. For patients who developed lung cancer during the 3-year follow-up period, the local spherical lung density of the precancerous area was individually quantified. Results Lung cancer was newly diagnosed in 21 participants (2.3% per year). The percent-age of low attenuation area in patients who developed lung cancer was higher than that of the other patients (20.0% vs 10.4%, P=0.014). The presence of emphysema (odds ratio [OR] 4.2, 95% confidence interval [CI] 1.0–29.0, P=0.049) or interstitial lung abnormalities (OR 15.6, 95% CI 4.4–65.4, P<0.0001) independently increased the risk for lung cancer. Compared with the density of the entire lung, the local density of the precancerous area was almost the same in patients with heterogeneous emphysema, but it was higher in most patients with interstitial abnormalities. Conclusion The presence of emphysema or interstitial abnormalities or a combination of both were independent predictors of lung cancer development in COPD patients. Furthermore, lung cancer most often developed in non-emphysematous areas or in interstitial abnormalities.

Relationship between diminution of small pulmonary vessels and emphysema in chronic obstructive pulmonary disease

OBJECTIVES To investigate the relationship between small pulmonary vessels and extent of emphysema on CT in individual lungs with chronic obstructive pulmonary disease (COPD). METHODS Forty-nine patients were included. The percentage of cross-sectional area of vessels <5mm2 (%CSA <5) and extent of emphysema were assessed. RESULTS Less than half of the COPD patients demonstrated an inverse correlation between %CSA <5 and percentage of low attenuation area (LAA%). In the remaining patients, %CSA <5 was homogeneously distributed. CONCLUSION Not all patients with COPD demonstrated an inverse correlation of the distributions between %CSA <5 and LAA% in individual lungs.

Multiple nodular lesions following Pneumocystis pneumonia in a non-HIV immunocompromised patient.

Cytomegalovirus superinfection is associated with a poor prognosis in non‐HIVPneumocystis pneumonia (PCP) and can cause deterioration of PCP not only simultaneously but also after initiating PCP treatment. Cytomegalovirus pneumonia should be considered in cases with deterioration after initiating PCP treatment; multiple nodular lesions are useful findings for the diagnosis.