BackgroundThere is considerable heterogeneity in the rate of lung function decline in chronic obstructive pulmonary disease (COPD), the determinants of which are largely unknown. Observational studies in COPD indicate that low body mass index (BMI) is associated with worse outcomes, and overweight/obesity has a protective effect – the so-called “obesity paradox”. We aimed to determine the relationship between BMI and the rate of FEV1 decline in data from published clinical trials in COPD.MethodsWe performed a systematic review of the literature, and identified 5 randomized controlled trials reporting the association between BMI and FEV1 decline. Four of these were included in the meta-analyses. We analyzed BMI in 4 categories: BMI-I (< 18.5 or <  20 kg/m2), BMI-II (18.5 or 20 to < 25 kg/m2), BMI-III (25 to < 29 or < 30 kg/m2) and BMI-IV (≥29 or ≥ 30 kg/m2). We then performed a meta-regression of all the estimates against the BMI category.ResultsThe estimated rate of FEV1 decline decreased with increasing BMI. Meta-regression of the estimates showed that BMI was significantly associated with the rate of FEV1 decline (linear trend p = 1.21 × 10− 5).ConclusionsThese novel findings support the obesity paradox in COPD: compared to normal BMI, low BMI is a risk factor for accelerated lung function decline, whilst high BMI has a protective effect. The relationship may be due to common but as-of-yet unknown causative factors; further investigation into which may reveal novel endotypes or targets for therapeutic intervention.

A high prevalence of bronchiectasis was found by chest computed tomography (CT) in patients with moderate–severe chronic obstructive pulmonary disease (COPD), and it was shown to be associated with more severe symptoms, higher frequency of exacerbations and mortality. The risk factors for bronchiectasis in COPD are not yet clarified.High-resolution computed tomography (HRCT) of chest was performed in patients with moderate–severe COPD, and the presence and the extent of bronchiectasis were evaluated by two radiologists. Demographic data, respiratory symptoms, lung function, previous pulmonary tuberculosis, serum inflammatory markers, serum total immunoglobulin E (T-IgE), and sputum culture of Pseudomonas aeruginosa were compared between those with and without bronchiectasis. Multivariate logistic regression analysis was used to determine the independent factors associated with bronchiectasis.We enrolled 190 patients with stable COPD, of which 87 (87/190, 45.8%) had bronchiectasis on HRCT. Compared with those without bronchiectasis, COPD patients with bronchiectasis were more likely to be males (P = 0.021), had a lower body mass index (BMI) (P = 0.019), a higher prevalence of previous tuberculosis (P = 0.005), longer history of dyspnea (P < 0.001), more severe dyspnea (P = 0.041), higher frequency of acute exacerbation (P = 0.002), higher serum concentrations of C-reactive protein (CRP) (P = 0.017), fibrinogen (P = 0.016), and T-IgE [P = 0.004; for log10(T-IgE), P <0.001]. COPD patients with bronchiectasis also showed poorer lung function (for FEV1/FVC, P = 0.013; for FEV1%predicted, P = 0.012; for global initiative for chronic obstructive lung disease (GOLD) grades, P = 0.035), and a higher positive rate of sputum P aeruginosa (P = 0.020). Logistic regression analysis demonstrated that male gender (P = 0.021), previous tuberculosis (P = 0.021), and increased level of serum T-IgE [for log10(T-IgE), P < 0.001] were risk factors for coexistent bronchiectasis. More notably, the level of serum T-IgE [log10(T-IgE)] was positively correlated with the extent of bronchiectasis in COPD patients (r = 0.208, P = 0.05).Higher serum T-IgE, male gender, and previous tuberculosis are independent risk factors for coexistent bronchiectasis in COPD. The association of T-IgE with the extent of bronchiectasis also suggests that further investigations are needed to explore the potential role of IgE in the pathogenesis of bronchiectasis in COPD.

Nano nickel oxide (NiO), widely used in industry, has recently been discovered to have pulmonary toxicity. However, no subchronic exposure studies about nano NiO-induced pulmonary fibrosis have been reported. The objective of this study was to investigate pulmonary fibrosis induced by nano NiO and its potential mechanism in rats. Male Wistar rats ( n = 40, 200–240 g) were randomized into control group, nano NiO groups (0.015, 0.06, and 0.24 mg/kg), and micro NiO group (0.024 mg/kg). All rats were killed to collect lung tissue after intratracheal instillation of NiO particles twice a week for 6 weeks. To identify pulmonary fibrosis, Masson trichrome staining, hydroxyproline content, and collagen protein expression were performed. The results showed widespread lung fibrotic injury in histological examination and increased content of hydroxyproline, collagen types I and III in rat lung tissue exposed to nano NiO. To explore the potential pulmonary fibrosis mechanism, transforming growth factor beta 1 (TGF- β1) content was measured by enzyme-linked immunosorbent assay, and the messenger RNA expression of key indicators was detected by reverse transcription-quantitative polymerase chain reaction (RT-qPCR). The TGF- β1 content was increased in nano NiO exposure groups, as well as the upregulated gene expression of TGF- β1, Smad2, Smad4, matrix metalloproteinase, and tissue inhibitor of metalloproteinase. The findings indicated that nano NiO could induce pulmonary fibrosis, which may be related to TGF- β1 activation.

High-mobility group box 1 (HMGB1) shows pro-inflammatory activity in various inflammatory diseases and has been found up-regulated in chronic obstructive pulmonary disease (COPD). Lung macrophages play an important role in airway inflammation and lung destruction in COPD, yet whether HMGB1 is involved in ciga-

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Pulmonary tuberculosis (PTB) is a risk factor for COPD. Our previous study revealed more severe emphysema in COPD patients (mostly smokers) with prior tuberculosis. However, the mechanisms of interactions between cigarette smoke (CS) and Mycobacterium tuberculosis (Mtb) are unknown. In this study, we found that the frequencies of both M1 and M2 macrophages, and levels of MMP9 and MMP12 in bronchoalveolar lavage were increased in PTB patients with smoking. Between-group analysis showed that the frequency of M1 macrophages was higher in non-smoker PTB patients while more M2 macrophages were found in smokers without PTB, as compared to the non-smoker healthy controls. Bacille Calmette-Guérin (BCG) infection in CS extract (CSE)-incubated MH-S cells further enhanced secretion of M1-related (iNOS, IFN-γ and TNF-α) and M2-related (TGF-β and IL-10) cytokines, reactive oxygen species (ROS) production and cellular apoptosis, concomitantly with up-regulation of MMP9 and MMP12, but not TIMP1. Moreover, BCG infection in acutely CS-exposed mice promoted macrophage polarization toward both M1 and M2 phenotypes, along with increased lung inflammatory infiltration. MMP9 and MMP12, but not TIMP1, were further up-regulated in lung tissues and BAL fluid after BCG infection in this model. Taken together, Mtb Infection promoted CS-exposed macrophages to polarize toward both M1 and M2 phenotypes, along with enhanced production of MMP9 and MMP12. These findings provide insights into the mechanistic interplay between CS exposure and tuberculosis in the pathogenesis of COPD.

Statins, the 3-hydroxy-3-methylglutaryl-cooenzyme A (HMG-CoA) reductase inhibitors, have been shown to inhibit the migration of macrophages and smooth muscle cell proliferation leading to an antiproliferative effect. Although this beneficial effect of statins has been suggested to be independent of lipid lowering properties, the possible mechanisms responsible for this action is largely unknown. Gap junctions, which serve as channels for direct intercellular exchange of ions, secondary messengers, and small signaling molecules, play an important role in tissue homeostasis and regulation of growth, differentiation, and development. This study was designed to test the hypothesis that expression of the component proteins of gap junctions, connexins 40 and 43 (Cx40 and Cx43), is upregulated in arteries subjected to balloon injury and that this upregulation can be suppressed by statin therapy. Male New Zealand white rabbits were subjected to injury in which an angioplasty catheter was introduced into the right iliac artery from the femoral artery under fluoroscopic guidance. Five groups of rabbits (n = 6 to 7) were treated for 2 weeks with one of the following: balloon injury (BL); BL+lovastatin (BL+L, 10 mg/kg/day); BL+fluvastatin (BL+F, 10 mg/kg/day); sham operation (Sham); and control (Con). Immunohistochemistry studies showed that Cx40 and Cx43 were expressed in normal smooth muscle cells (SMC) throughout the media. Reverse transcription-polymerase chain reaction and Western blot analysis showed that Cx40 and Cx43 mRNA and protein expression was elevated after injury (P < .001 for both proteins and both assays), and these elevations were suppressed by lovastatin and fluvastatin to a similar degree (P < .05 for both drugs and both assays). Immunostaining of Cx40 and Cx43 was consistently enhanced in the neointimal area after injury and lovastatin and fluvastatin reduced staining of these proteins in the lessened neointimal layer. Transmission electron microscopy revealed that there were abundant gap junctions between neointimal SMC as well as fewer and smaller gap junctions after statin treatment. Therefore, balloon injury causes upregulation of Cx40 and Cx43 in neointimal SMC. Lovastatin and fluvastatin suppress upregulated Cx40 and Cx43 expression and reduce neointimal proliferation, suggesting that Cx40 and Cx43 may play a role in statin-induced antiproliferative effect.

Background: Preserved ratio impaired spirometry (PRISm), characterized by the decreased forced expiratory volume in 1 s (FEV1) and forced vital capacity (FVC) with a preserved FEV1/FVC ratio, is highly prevalent and heterogeneous. We aimed to identify the subtypes of PRISm and examine their differences in clinical characteristics, long-term mortality risks, and longitudinal transition trajectories.Methods: A total of 6,616 eligible subjects were included from the English longitudinal study of aging. Two subtypes of the PRISm were identified as mild PRISm (either of FEV1 and FVC &lt;80% predicted value, FEV1/FVC ≥0.7) and severe PRISm (both FEV1 and FVC &lt;80% predicted values, FEV1/FVC ≥0.7). Normal spirometry was defined as both FEV1 and FVC ≥80% predicted values and FEV1/FVC ≥0.7. Hazard ratios (HRs) and 95% CIs were calculated by the multiple Cox regression models. Longitudinal transition trajectories were described with repeated spirometry data.Results: At baseline, severe PRISm had increased respiratory symptoms, including higher percentages of phlegm, wheezing, dyspnea, chronic bronchitis, and emphysema than mild PRISm. After an average of 7.7 years of follow-up, severe PRISm significantly increased the risks of all-cause mortality (HR=1.91, 95%CI = 1.58–2.31), respiratory mortality (HR = 6.02, 95%CI = 2.83–12.84), and CVD mortality (HR = 2.11, 95%CI = 1.42–3.13) compared with the normal spirometry, but no significantly increased risks were found for mild PRISm. In the two longitudinal transitions, mild PRISm tended to transition toward normal spirometry (40.2 and 54.7%), but severe PRISm tended to maintain the status (42.4 and 30.4%) or transition toward Global Initiative for Chronic Obstructive Lung Disease (GOLD)2–4 (28.3 and 33.9%).Conclusion: Two subtypes of PRISm were identified. Severe PRISm had increased respiratory symptoms, higher mortality risks, and a higher probability of progressing to GOLD2–4 than mild PRISm. These findings provided new evidence for the stratified management of PRISm.