Lysophospholipid Acyltransferase 9 Promotes Emphysema Formation via Platelet-activating Factor.

Cigarette smoking is known to be the leading cause of chronic obstructive pulmonary disease (COPD). However, the detailed mechanisms have not been elucidated. PAF (platelet-activating factor), a potent inflammatory mediator, is involved in the pathogenesis of various respiratory diseases such as bronchial asthma and COPD. We focused on LPLAT9 (lysophospholipid acyltransferase 9), a biosynthetic enzyme of PAF, in the pathogenesis of COPD. LPLAT9 gene expression was observed in excised COPD lungs and single-cell RNA sequencing data of alveolar macrophages (AMs). LPLAT9 was predominant and upregulated in AMs, particularly monocyte-derived AMs, in patients with COPD. To identify the function of LPLAT9/PAF in AMs in the pathogenesis of COPD, we exposed systemic LPLAT9-knockout (LPALT9-/-) mice to cigarette smoke (CS). CS increased the number of AMs, especially the monocyte-derived fraction, which secreted MMP12 (matrix metalloprotease 12). Also, CS augmented LPLAT9 phosphorylation/activation on macrophages and, subsequently, PAF synthesis in the lung. The LPLAT9-/- mouse lung showed reduced PAF production after CS exposure. Intratracheal PAF administration accumulated AMs by increasing MCP1 (monocyte chemoattractant protein-1). After CS exposure, AM accumulation and subsequent pulmonary emphysema, a primary pathologic change of COPD, were reduced in LPALT9-/- mice compared with LPLAT9+/+ mice. Notably, these phenotypes were again worsened by LPLAT9+/+ bone marrow transplantation in LPALT9-/- mice. Thus, CS-induced LPLAT9 activation in monocyte-derived AMs aggravated pulmonary emphysema via PAF-induced further accumulation of AMs. These results suggest that PAF synthesized by LPLAT9 has an important role in the pathogenesis of COPD.

Participant Selection from the General Japanese Population for Pulmonary Function Tests Using a Questionnaire on Symptoms and Smoking Habits during Annual Health Checkups: The Yamagata-Takahata Study.

Objective Pulmonary function tests are essential for diagnosing respiratory diseases, such as chronic obstructive pulmonary disease (COPD), but are typically not performed in Japan during annual health checkups, which hinders the early diagnosis of respiratory diseases. Methods Individuals who agreed to participate in the Yamagata-Takahata study during medical checkups in Takahata (Yamagata Prefecture, Japan) in 2011 were examined. We interviewed 669 participants (49.0% men; mean age, 67.7 years old) regarding their respiratory symptoms and smoking habits and performed pulmonary function tests during the study. Results Based on pulmonary function test results, 141 participants had pulmonary dysfunction, and 115 had obstructive pulmonary dysfunction. The risk of respiratory dysfunction, particularly obstructive respiratory dysfunction, was examined by referring to a questionnaire tool for an early COPD diagnosis. The associations between age, the smoking history, respiratory symptoms, and obstructive respiratory dysfunction were evaluated. Obstructive respiratory dysfunction was found in 17.6% of participants ≥50 years old and 19.5% ≥60 years old, 30.3% had a smoking history, and 32.8% had respiratory symptoms. Furthermore, the participants with multiple factors had a higher probability of obstructive respiratory dysfunction. Conclusion Subjects with obstructive pulmonary dysfunction are expected to be efficiently identified by extracting individuals by age and smoking habit and through a respiratory symptom questionnaire, although pulmonary function tests cannot be performed for all individuals during health checkups.

Effect of hyperhomocysteinemia on a murine model of smoke-induced pulmonary emphysema.

Hyperhomocysteinemia was reported to enhance endoplasmic reticulum (ER) stress and subsequent apoptosis in several cells. However, the precise mechanisms of smoking susceptibility associated with hyperhomocysteinemia has not been fully elucidated. This study included 7- to 9-week-old C57BL6 male mice induced with hyperhomocysteinemia and were exposed to cigarette smoke (CS). A549 cells (human alveolar epithelial cell line) were cultured with homocysteine and were exposed to cigarette smoke extract (CSE) to observe cell viability and expression of proteins related to the ER stress. After 6 months of CS exposure, pulmonary emphysema was more severely induced in the group under the condition of hyperhomocysteinemia compared to that in the control group. The apoptotic A549 cells increased as homocysteine concentration increased and that was enhanced by CSE. Protein expression levels of ER stress markers were significantly increased after simultaneous stimulation. Notably, vitamin B12 and folate supplementation improved ER stress after simultaneous stimulation of A549 cells. In this study, we showed that hyperhomocysteinemia exacerbates CS exposure-induced emphysema in mice, suggesting that hyperhomocysteinemia and CS stimulation enhance ER stress and subsequent induced apoptosis in alveolar epithelial cells. It was suggested that there is a synergistic effect between homocysteine and CS.

Role of CC Chemokine Ligand 17 in Mouse Models of Chronic Obstructive Pulmonary Disease.

Lung function deterioration is significantly associated with poor prognosis in patients with chronic obstructive pulmonary disease (COPD). We previously reported that CC chemokine ligand 17/thymus and activation-regulated chemokine (CCL17/TARC) could be a predictive factor of lung function decline in patients with COPD. However, the role of CCL17 in the pathogenesis of COPD is unclear. Here we examined the role of CCL17 in lung inflammation using mouse COPD models. Exposure to cigarette smoking induced CCL17 production in bronchial epithelial cells and accumulation of alveolar macrophages in the lungs. Intranasal administration of recombinant CCL17 further enhanced cigarette smoke-induced macrophage accumulation and also aggravated elastase-induced pulmonary emphysema. We confirmed that cigarette smoke (CS) extract as well as hydrogen peroxide upregulated CCL17 in BAES-2B cells. Of note, macrophages of both M1 and M2 surface markers were accumulated by cigarette smoke. Both alveolar macrophage accumulation via exposure to cigarette smoking and emphysematous changes induced by elastase administration were significantly reduced in CCL17-deficient mice. We further demonstrated that CCL17 strongly induced the expression of CC chemokine ligand 2 (CCL2), a chemoattractant for macrophages, in RAW264.7 cells, and its production was inhibited by knockdown of CCR4, the receptor of CCL17. Collectively, the present results demonstrate that CCL17 is produced by lung epithelial cells upon CS exposure. Furthermore, CCL17 is involved in CS-induced accumulation of alveolar macrophages and development of elastase-induced pulmonary emphysema, possibly through CCL17-induced production of CCL2 by macrophages. Our findings may provide a new insight into the pathogenesis of COPD.

The Incidence and Risk Analysis of Lung Cancer Development in Patients with Chronic Obstructive Pulmonary Disease: Possible Effectiveness of Annual CT-Screening.

PURPOSE: Lung cancer is a serious complication in patients with chronic obstructive pulmonary disease (COPD) and accounts for approximately 15% of deaths in patients with COPD. However, with the exception of emphysema, few reports to date have been published on the factors that predict lung cancer development in COPD patients. It has been reported that patients with COPD develop lung cancer at a rate of 0.8% - 1.7%/year, but the incidence may be higher in the Japanese population. Therefore, we investigated the incidence of lung cancer and the lung cancer mortality rate in Japanese COPD patients, as well as factors that are associated with the development of lung cancer in COPD patients. PATIENTS AND METHODS: We followed up 224 patients with stable COPD and performed CT examinations at least once per year. The incidence of lung cancer was recorded and data at enrollment were compared with data of the group that did not develop lung cancer. RESULTS: Over a median follow-up period of 4.58 years, lung cancer was newly diagnosed in 19 patients; the incidence of lung cancer in this population was 1.85%/year. Patients who developed lung cancer had more severe emphysema assessed by CT and GOLD classification and were more likely to be current smokers than those who did not develop lung cancer. No other significant differences were observed between these two groups. Mortality was significantly increased in patients who developed lung cancer compared with those who did not. CONCLUSION: In COPD patients, the incidence of lung cancer is higher and the development of lung cancer worsens the prognosis; however, lung cancer development is unpredictable and attention should be paid to all patients. Annual CT screening is important for early detection of lung cancer.

Effect of Iron Deficiency on a Murine Model of Smoke-induced Emphysema.

Smoking is a major risk factor for chronic obstructive pulmonary disease (COPD). Smoking susceptibility is important for the onset and development of COPD. We previously reported an association between serum iron concentrations and pulmonary function in male smokers. However, the mechanism governing smoking susceptibility in relation to iron deficiency is unclear; this study aimed to elucidate this mechanism. C57BL/6 male mice were fed an iron-deficient or normal diet and then exposed to cigarette smoke. BAL, histological analysis, and pulmonary function tests were performed after cigarette smoke exposure. Human alveolar type II epithelial A549 cells were treated with an iron chelator. Subsequently, A549 cells were exposed to cigarette smoke extract. In mice exposed to cigarette smoke for 2 weeks, the concentration of alveolar macrophages in the BAL fluid recovered from iron-deficient mice was significantly higher than that in normal diet mice. IL-6 and MCP-1 (monocyte chemotactic protein 1) concentrations in the BAL fluid increased significantly from baseline in iron-deficient mice, but not in normal diet mice. In mice exposed to cigarette smoke for 8 weeks, the pathological mean linear intercepts, physiological total lung capacity, and functional residual capacity in the lungs of iron-deficient mice were significantly greater than in normal diet mice. Phosphorylation of NF-κB was enhanced in the lungs of iron-deficient mice exposed to cigarette smoke and in the iron-chelating A549 cells exposed to cigarette smoke extract. Iron deficiency exaggerated cigarette smoke-induced pulmonary inflammation, suggesting that it may accelerate COPD development.

Examination of predictable factors of perioperative respiratory complications by preoperative forced oscillation technique parameters.

In this study, we investigated whether pulmonary function tests such as forced oscillation technique parameters could predict perioperative respiratory complications. In the results of our study, perioperative respiratory complications cannot be predicted using the results of preoperative pulmonary function tests and forced oscillation technique parameters. Patients who are judged by comprehensive preoperative judgment to be suitable for general anesthesia may not need to consider the risk of perioperative complications using pulmonary function test.

Impact of cigarette smoking on decline in forced expiratory volume in 1s relative to severity of airflow obstruction in a Japanese general population: The Yamagata-Takahata study.

BACKGROUND: Few studies are available regarding the annual decline of forced expiratory volume in 1s (FEV1) in chronic obstructive pulmonary disease patients with mild airflow obstruction. This study sought to clarify to what extent cigarette-smoking individuals with mild airflow obstruction lose pulmonary function annually. METHODS: From 2004 to 2006, pulmonary function tests were performed on people >40 years of age, during the annual health checkup held in Takahata, Yamagata, Japan (initial study population, n=3253). In 2011, pulmonary function tests were performed again on participants who agreed to undergo reexamination (follow-up study population, n=838). RESULTS: Smokers have decreased pulmonary function in terms of percent forced vital capacity (FVC), %FEV1, and FEV1/FVC; the stages of airflow obstruction were also more severe in smokers than never-smokers. The annual decline in FEV1 was significantly greater in smokers than in never-smokers. The median annual decline in FEV1 was most significant in individuals with mild airflow obstruction. The annual decline in FEV1 was greater in smokers with mild airflow obstruction than in smokers with moderate airflow obstruction. In analyzing the decline in %FEV1, the annual change in smokers with mild airflow obstruction was greater than that in smokers with normal spirometric values. CONCLUSION: The annual decline in FEV1 was most significant in smokers with mild airflow obstruction in a Japanese general population. This highlights the importance of early detection of chronic obstructive pulmonary disease patients among the general population in order to prevent disease progression in undiagnosed patients.

MafB enhances efferocytosis in RAW264.7 macrophages by regulating Axl expression.

The transcription factor MafB is involved in cellular differentiation and phagocytosis in macrophages. Macrophages phagocytose apoptotic cells in vivo; this process, which is known as efferocytosis, requires Axl receptor tyrosine kinase (Axl) activity. However, the association between MafB and efferocytosis, as well as that between MafB and Axl, in macrophages is unknown. We hypothesized that MafB modulates macrophage efferocytosis by regulating Axl expression. Fluorescent-labeled apoptotic thymocytes were added to RAW264.7-MafB-shRNA and control cells, and the proportion of phagocytosis-positivey fluorescence microscopy and flow cytometry. In addition, Axl mRNA and protein were quantified by real-time PCR and western blotting in each group. RAW264.7-MafB-shRNA cells were transfected with a plasmid expressing green fluorescent protein (GFP)-tagged Axl or a control empty plasmid expressing only GFP. The capacity for phagocytosis of apoptotic cells was assessed in GFP-positive cells gated based on fluorescence intensity. In RAW264.7-MafB-shRNA cells, capacity for phagocytosis of apoptotic thymocytes was significantly reduced compared with that of control cells, as determined by fluorescence microscope and flow cytometry. Axl mRNA and protein expression was significantly reduced in RAW264.7-MafB-shRNA cells relative to control cells. Furthermore, the capacity of RAW264.7-MafB-shRNA cells, transfected with an Axl-expressing plasmid, for phagocytosis of apoptotic thymocytes was significantly greater than that of cells transfected with the control plasmid. Collectively, the present findings indicate that MafB enhances efferocytosis by regulating Axl expression in RAW264.7 macrophages.

MafB silencing in macrophages does not influence the initiation and growth of lung cancer induced by urethane.

An increased number of tumor-associated macrophages (TAMs) that exhibit the M2 macrophage phenotype is related to poorer prognosis in cancer patients. MafB is a transcription factor regulating the differentiation of macrophages. However, involvement of MafB for the development of TAMs is unknown. This study was designed to investigate the role of MafB in a murine urethane-induced lung cancer model. Urethane was injected intraperitoneally into wild-type and dominant-negative MafB transgenic mice. Twenty-four weeks later, mice were sacrificed and their lungs removed for pathological analysis. The numbers and mean areas of lung cancer were evaluated. In addition, the numbers of Mac-3-positive macrophages were evaluated in each tumor. The numbers and mean areas of lung cancer induced by urethane administration were not significantly different between wild-type and dominant-negative MafB transgenic mice. The numbers of TAMs in lung cancer tissue were not significantly different between the two groups. MafB silencing using dominant-negative MafB did not influence the initiation and growth of lung cancer in mice exposed to urethane. These data suggest that MafB may not be related to the development of TAMs.

Role of chemokine C-C motif ligand-1 in acute and chronic pulmonary inflammations.

BACKGROUND: Chemokine C-C motif ligand 1 (CCL1) accumulates C-C motif chemokine receptor 8 positive leukocytes to the inflammatory sites. Single-nucleotide polymorphisms in the chemokine CCL1 gene are associated with exacerbation of chronic obstructive lung disease. However, it is unclear whether CCL1 has immunomodulatory functions during pulmonary inflammation. This study aimed to elucidate this issue using newly generated transgenic mice that express CCL1 in the lungs (SPC-CCL1 mice). METHODS: To evaluate the phenotypes of these mice, lung section and bronchoalveolar lavage (BAL) fluid analyses were performed. We intratracheally administered lipopolysaccharide (LPS) or Mycobacterium bovis as a model of acute or chronic lung inflammation, respectively. RESULTS: No histological differences were observed between lung tissue from SPC-CCL1 Tg and wild-type mice in the resting condition and after LPS administration. In the resting condition, the total BAL cell concentration was lower in SPC-CCL1 Tg mice than in wild-type mice (P = 0.0097). Flow cytometric analyses showed that SPC-CCL1 Tg mice had fewer F4/80-positive cells than wild-type mice (P = 0.0278). After intratracheal LPS administration, CCL1 overexpression changed neither the total numbers nor population of BAL cells. After mycobacterial administration, pulmonary granuloma formation was significantly enhanced. The degree of Immunostaining for endoplasmic reticulum to nucleus signaling 1, a molecule associated with granuloma formation and endoplasmic reticulum stress, was significantly enhanced in the granuloma regions of SPC-CCL1 mice treated with Mycobacterium, compared to those of wild-type mice. CONCLUSIONS: CCL1 overexpression in the lungs did not change the acute inflammatory response induced by LPS, but enhanced granuloma formation after mycobacterial treatment, possibly through enhancing endoplasmic reticulum stress.

The role of macrophage transcription factor MafB in atherosclerotic plaque stability.

BACKGROUND AND AIMS: Macrophage differentiation is associated with the development of atherosclerosis and plaque vulnerability and is regulated by transcription factor MafB. We previously reported that MafB attenuates macrophage apoptosis, which is associated with atherosclerotic plaque instability. The aim of this study was to elucidate the role of MafB in the progression of atherosclerotic plaque. METHODS: We generated macrophage-specific dominant-negative (DN) MafB transgenic mice and intercrossed DN-MafB mice with apolipoprotein E (ApoE) knockout (KO) mice. RESULTS: There was no significant difference in advanced atherosclerotic lesion area between DN-MafB/ApoE KO mice and littermate control ApoE KO mice 9 weeks after high-cholesterol diet. However, DN-MafB/ApoE KO mice showed significantly larger necrotic cores and lower collagen content in atherosclerotic plaques than ApoE KO mice. Although there was no difference in intraplaque macrophage infiltration and efferocytosis, DN-MafB/ApoE KO mice showed significantly more apoptotic macrophages at the plaque edges than did ApoE KO mice. Real-time PCR analysis revealed that peritoneal macrophages of DN-MafB/ApoE KO mice had a greater increase in matrix metalloproteinase-9 and mRNA expression of inflammatory/M1 macrophage markers (tissue necrosis factor-α, interleukin-6, CD11c, and p47phox) after lipopolysaccharide stimulation than those of ApoE KO mice. CONCLUSION: Macrophage-specific inhibition of MafB may destabilize atherosclerotic plaques in advanced lesions.

Inhibition of elastase-pulmonary emphysema in dominant-negative MafB transgenic mice.

Alveolar macrophages (AMs) play important roles in the pathogenesis of chronic obstructive pulmonary disease (COPD). We previously demonstrated upregulation of the transcription factor MafB in AMs of mice exposed to cigarette smoke. The aim of this study was to elucidate the roles of MafB in the development of pulmonary emphysema. Porcine pancreatic elastase was administered to wild-type (WT) and dominant-negative (DN)-MafB transgenic (Tg) mice in which MafB activity was suppressed only in macrophages. We measured the mean linear intercept and conducted cell differential analysis of bronchoalveolar lavage (BAL) cells, surface marker analysis using flow cytometry, and immunohistochemical staining using antibodies to matrix metalloproteinase (MMP)-9 and MMP-12. Airspace enlargement of the lungs was suppressed significantly in elastase-treated DN-MafB Tg mice compared with treated WT mice. AMs with projected pseudopods were decreased in DN-MafB Tg mice. The number of cells intermediately positive for F4/80 and weakly or intermediately positive for CD11b, which are considered cell subsets of matured AMs, decreased in the BAL of DN-MafB Tg mice. Furthermore, MMP-9 and -12 were significantly downregulated in BAL cells of DN-MafB Tg mice. Because MMPs exacerbate emphysema, MafB may be involved in pulmonary emphysema development through altered maturation of macrophages and MMP expression.

Reduced number and morphofunctional change of alveolar macrophages in MafB gene-targeted mice.

Alveolar macrophages (AMs) play an important role in the pathogenesis of chronic obstructive pulmonary disease (COPD). We previously demonstrated that the transcription factor, MafB, increased in the AMs of mice exposed to cigarette smoke, and in those of human patients with COPD. The aim of this study was to evaluate the role of MafB in AMs using newly established transgenic (TG) mice that specifically express dominant negative (DN) MafB in macrophages under the control of macrophage scavenger receptor (MSR) enhancer-promoter. We performed cell differential analyses in bronchoalveolar lavage cells, morphological analyses with electron microscopy, and flow cytometry-based analyses of surface markers and a phagocytic capacity assay in macrophages. AM number in the TG mice was significantly decreased compared with wild-type (WT) mice. Morphologically, the high electron density area in the nucleus increased, the shape of pseudopods on the AMs was altered, and actin filament was less localized in the pseudopods of AMs of TG mice, compared with WT mice. The expression of surface markers, F4/80 and CD11b, on peritoneal macrophages in TG mice was reduced compared with WT mice, while those on AMs remained unchanged. Phagocytic capacity was decreased in AMs from TG mice, compared with WT mice. In conclusion, MafB regulates the phenotype of macrophages with respect to the number of alveolar macrophages, the nuclear compartment, cellular shape, surface marker expression, and phagocytic function. MSR-DN MafB TG mice may present a useful model to clarify the precise role of MafB in macrophages.

Impact of cigarette smoking on maximal expiratory flows in a general population: the Takahata study.

BACKGROUND: Maximal expiratory flows (MEFs) depend on the elastic recoil pressure in the alveoli, airway resistance and bronchial collapsibility. MEFs at lower levels of vital capacity [MEFs at x% FVC (MEF(x))] would indicate the patency of peripheral airways. In Japan, a ratio of MEF(50) to MEF(25) (MEF(50)/MEF(25)) greater than 4.0 is used as an index of injury to the small airways in subjects without airflow limitation. However, to date there have been no epidemiological investigations relating to this index. The aim of this study was to evaluate the impact of cigarette smoking on MEFs in a general population, and to assess the validity of using this index to evaluate injury to the small airways. METHODS: Subjects aged 40 years or older (n=2,917), who had participated in a community-based annual health-check in Takahata, Japan, were enrolled in the study. MEF(75), MEF(50) and MEF(25) were measured in these subjects. RESULTS: In smokers, as compared with never-smokers, the percentage predicted MEFs (%MEFs) decreased according to the aging of the population, except in the case of %MEF(25) in females. In males, but not in females, %MEFs decreased significantly with an increase in cigarette consumption. In both genders, MEF(50)/MEF(25) was slightly, but significantly, elevated with aging of the population. In addition, 36.5% of subjects who participated in this health-check had MEF(50)/MEF(25) values greater than 4.0. No difference in MEF(50)/MEF(25) was observed between smokers and never-smokers. CONCLUSION: Cigarette smoking enhanced the age-related decline in MEFs. Since many healthy subjects aged 40 years or older have MEF(50)/MEF(25) values greater than 4.0, the use of this criterion may over-estimate the presence of small airway disease.

Two cases of bronchiolitis obliterans organizing pneumonia syndrome after postoperative irradiation for breast cancer.

We report two cases of bronchiolitis obliterans organizing pneumonia (BOOP) syndrome that developed after postoperative radiation therapy for breast cancer. In both patients, chest radiographs and computed tomography (CT) showed multiple consolidations outside the irradiation fields after several months of tangential radiation therapy. These patients were diagnosed as having radiation-associated BOOP syndrome, based on their clinical course and the findings on examination. After treatment with a systemic corticosteroid, radiographic consolidations and symptoms improved rapidly. In cases where consolidations appear outside the irradiated field, it is important to consider BOOP syndrome as a pulmonary complication of radiation therapy for breast cancer.