Role of activin-A in cigarette smoke-induced inflammation and COPD.

Activin-A is a pleiotropic cytokine belonging to the transforming growth factor-ß superfamily and has been implicated in asthma and pulmonary fibrosis. However, the role of activin-A and its endogenous inhibitor, follistatin, in the pathogenesis of chronic obstructive pulmonary disease (COPD) is unknown. We first quantified activin-A and follistatin in the lungs of air- or cigarette smoke-exposed mice and in the lungs of patients with COPD by immunohistochemistry, ELISA and quantitative real-time PCR. We subsequently studied the effect of cigarette smoke on primary human bronchial epithelial cells in vitro. Next, activin-A signalling was antagonised in vivo by administration of follistatin in mice exposed to air or cigarette smoke for 4 weeks. Protein levels of activin-A were increased in the airway epithelium of patients with COPD compared with never-smokers and smokers. Cigarette smoke-exposed human bronchial epithelial cells expressed higher levels of activin-A and lower levels of follistatin. Both mRNA and protein levels of activin-A were increased in the lungs of cigarette smoke-exposed mice, whereas follistatin levels were reduced upon cigarette smoke exposure. Importantly, administration of follistatin attenuated the cigarette smoke-induced increase of inflammatory cells and mediators in the bronchoalveolar lavage fluid in mice. These results suggest that an imbalance between activin-A and follistatin contributes to the pathogenesis of cigarette smoke-induced inflammation and COPD.

MicroRNA expression in induced sputum of smokers and patients with chronic obstructive pulmonary disease.

RATIONALE: Chronic obstructive pulmonary disease (COPD) is characterized by progressive inflammation in the airways and lungs combined with disturbed homeostatic functions of pulmonary cells. MicroRNAs (miRNAs) have the ability to regulate these processes by interfering with gene transcription and translation. OBJECTIVES: We aimed to identify miRNA expression in induced sputum and examined whether the expression of miRNAs differed between patients with COPD and subjects without airflow limitation. METHODS: Expression of 627 miRNAs was evaluated in induced sputum supernatant of 32 subjects by stem-loop reverse transcription-quantitative polymerase chain reaction. Differentially expressed miRNAs were validated in an independent replication cohort of 41 subjects. Enrichment of miRNA target genes was identified by in silico analysis. Protein expression of target genes was determined by ELISA. MEASUREMENTS AND MAIN RESULTS: Thirty-four miRNAs were differentially expressed between never-smokers and current smokers without airflow limitation in the screening cohort. Eight miRNAs were expressed at a significantly lower level in current-smoking patients with COPD compared with never-smokers without airflow limitation. Reduced expression of let-7c and miR-125b in patients with COPD compared with healthy subjects was confirmed in the validation cohort. Target genes of let-7c were significantly enriched in the sputum of patients with severe COPD. The concentration of tumor necrosis factor receptor type II (TNFR-II, implicated in COPD pathogenesis and a predicted target gene of let-7c) was inversely correlated with the sputum levels of let-7c . CONCLUSIONS: let-7c is significantly reduced in the sputum of currently smoking patients with COPD and is associated with increased expression of TNFR-II.

Effects of potent neutralizing antibodies from convalescent plasma in patients hospitalized for severe SARS-CoV-2 infection.

In a randomized clinical trial of 86 hospitalized COVID-19 patients comparing standard care to treatment with 300mL convalescent plasma containing high titers of neutralizing SARS-CoV-2 antibodies, no overall clinical benefit was observed. Using a comprehensive translational approach, we unravel the virological and immunological responses following treatment to disentangle which COVID-19 patients may benefit and should be the focus of future studies. Convalescent plasma is safe, does not improve survival, has no effect on the disease course, nor does plasma enhance viral clearance in the respiratory tract, influence SARS-CoV-2 antibody development or serum proinflammatory cytokines levels. Here, we show that the vast majority of patients already had potent neutralizing SARS-CoV-2 antibodies at hospital admission and with comparable titers to carefully selected plasma donors. This resulted in the decision to terminate the trial prematurely. Treatment with convalescent plasma should be studied early in the disease course or at least preceding autologous humoral response development.

Cigarette smoke induces PTX3 expression in pulmonary veins of mice in an IL-1 dependent manner.

BACKGROUND: Chronic obstructive pulmonary disease (COPD) is associated with abnormal inflammatory responses and structural alterations of the airways, lung parenchyma and pulmonary vasculature. Since Pentraxin-3 (PTX3) is a tuner of inflammatory responses and is produced by endothelial and inflammatory cells upon stimuli such as interleukin-1ß (IL-1ß), we hypothesized that PTX3 is involved in COPD pathogenesis. METHODS AND RESULTS: We evaluated whether cigarette smoke (CS) triggers pulmonary and systemic PTX3 expression in vivo in a murine model of COPD. Using immunohistochemical (IHC) staining, we observed PTX3 expression in endothelial cells of lung venules and veins but not in lung arteries, airways and parenchyma. Moreover, ELISA on lung homogenates and semi-quantitative scoring of IHC-stained sections revealed a significant upregulation of PTX3 upon subacute and chronic CS exposure. Interestingly, PTX3 expression was not enhanced upon subacute CS exposure in IL-1RI KO mice, suggesting that the IL-1 pathway is implicated in CS-induced expression of vascular PTX3. Serum PTX3 levels increased rapidly but transiently after acute CS exposure.To elucidate the functional role of PTX3 in CS-induced responses, we examined pulmonary inflammation, protease/antiprotease balance, emphysema and body weight changes in WT and Ptx3 KO mice. CS-induced pulmonary inflammation, peribronchial lymphoid aggregates, increase in MMP-12/TIMP-1 mRNA ratio, emphysema and failure to gain weight were not significantly different in Ptx3 KO mice compared to WT mice. In addition, Ptx3 deficiency did not affect the CS-induced alterations in the pulmonary (mRNA and protein) expression of VEGF-A and FGF-2, which are crucial regulators of angiogenesis. CONCLUSIONS: CS increases pulmonary PTX3 expression in an IL-1 dependent manner. However, our results suggest that either PTX3 is not critical in CS-induced pulmonary inflammation, emphysema and body weight changes, or that its role can be fulfilled by other mediators with overlapping activities.

Selective accumulation of langerhans-type dendritic cells in small airways of patients with COPD.

BACKGROUND: Dendritic cells (DC) linking innate and adaptive immune responses are present in human lungs, but the characterization of different subsets and their role in COPD pathogenesis remain to be elucidated. The aim of this study is to characterize and quantify pulmonary myeloid DC subsets in small airways of current and ex-smokers with or without COPD. METHODS: Myeloid DC were characterized using flowcytometry on single cell suspensions of digested human lung tissue. Immunohistochemical staining for langerin, BDCA-1, CD1a and DC-SIGN was performed on surgical resection specimens from 85 patients. Expression of factors inducing Langerhans-type DC (LDC) differentiation was evaluated by RT-PCR on total lung RNA. RESULTS: Two segregated subsets of tissue resident pulmonary myeloid DC were identified in single cell suspensions by flowcytometry: the langerin+ LDC and the DC-SIGN+ interstitial-type DC (intDC). LDC partially expressed the markers CD1a and BDCA-1, which are also present on their known blood precursors. In contrast, intDC did not express langerin, CD1a or BDCA-1, but were more closely related to monocytes.Quantification of DC in the small airways by immunohistochemistry revealed a higher number of LDC in current smokers without COPD and in COPD patients compared to never smokers and ex-smokers without COPD. Importantly, there was no difference in the number of LDC between current and ex-smoking COPD patients.In contrast, the number of intDC did not differ between study groups. Interestingly, the number of BDCA-1+ DC was significantly lower in COPD patients compared to never smokers and further decreased with the severity of the disease. In addition, the accumulation of LDC in the small airways significantly correlated with the expression of the LDC inducing differentiation factor activin-A. CONCLUSIONS: Myeloid DC differentiation is altered in small airways of current smokers and COPD patients resulting in a selective accumulation of the LDC subset which correlates with the pulmonary expression of the LDC-inducing differentiation factor activin-A. This study identified the LDC subset as an interesting focus for future research in COPD pathogenesis.

C-reactive protein levels, haplotypes, and the risk of incident chronic obstructive pulmonary disease.

RATIONALE: Chronic obstructive pulmonary disease (COPD) is characterized by substantial chronic inflammation in the pulmonary compartment as well as in the systemic circulation. OBJECTIVES: To investigate potentially causal association, we examined whether serum levels of high-sensitivity C-reactive protein (hsCRP) and variations in the CRP gene are associated with the risk of developing COPD. METHODS: This study is part of the Rotterdam Study, a prospective population-based cohort study among subjects aged 55 years or older. At baseline, 6,836 subjects without COPD had a blood sample available for assessment of hsCRP serum levels and haplotypes of the CRP gene. We analyzed the association between hsCRP levels, CRP gene haplotypes, and incident COPD with Cox proportional hazard models, adjusted for age, sex, and other confounders. MEASUREMENTS AND MAIN RESULTS: High levels of hsCRP (>3 mg/L) were associated with a significantly increased risk of incident COPD (hazard ratio [HR], 1.7; 95% confidence interval [CI], 1.16-2.49) compared with persons with low levels (<1 mg/L). The risk remained increased after adjusting for potential confounders and introducing a latency period of 3 years. The risk was most pronounced in former smokers (HR, 2.2; 95% CI, 1.12-3.74). hsCRP was not a risk factor in never smokers. No CRP single nucleotide polymorphism or haplotype was associated with a significantly increased or decreased COPD risk. CONCLUSIONS: Increased hsCRP levels are predictive for the occurrence of COPD in smokers. However, haplotypes of the CRP gene, which influence hsCRP levels, are not associated with an altered risk of developing COPD.

The role of dendritic cells in the pathogenesis of COPD: liaison officers in the front line.

Dendritic cells are professional antigen presenting cells linking innate and adaptive immune responses. Different dendritic cell subsets were identified in human lung, each with their own functional characteristics. As innate and adaptive immune responses are activated in Chronic Obstructive Pulmonary Disease (COPD), dendritic cells could play a role in the pathogenesis of this disease. Indeed, cigarette smoke appears to modulate dendritic cell function in vitro and alters dendritic cell numbers and function in cigarette smoke exposed mice. The number of pulmonary dendritic cells differs between COPD patients, smokers and non-smokers. Moreover, the number of Langerhans-type dendritic cells increases with the severity of the disease. In this review we will discuss the scientific evidence regarding the role of dendritic cells in COPD and we will put forward the concept of modulation of dendritic cell differentiation and function as a crucial step in the pathogenesis of COPD.

Prevalence, incidence, and lifetime risk for the development of COPD in the elderly: the Rotterdam study.

BACKGROUND: COPD is a major cause of chronic morbidity and mortality throughout the world. Although the prevalence of COPD is already well documented, there are only few studies regarding the incidence of COPD. METHODS: In a prospective population-based cohort study among subjects aged >or= 55 years, COPD was diagnosed with an algorithm based on the validation of hospital discharge letters, files from the general practitioner, and spirometry reports. RESULTS: In this study cohort of 7,983 participants, 648 cases were identified with incident COPD after a median follow-up time of 11 years (interquartile range, 7.8 years). This resulted in an overall incidence rate (IR) of 9.2/1,000 person-years (PY) [95% confidence interval (CI), 8.5 to 10.0]. The IR of COPD was higher among men (14.4/1,000 PY; 95% CI, 13.0 to 16.0) than among women (6.2/1,000 PY; 95% CI, 5.5 to 7.0), and higher in smokers than in never-smokers (12.8/1,000 PY; 95% CI, 11.7 to 13.9 and 3.9/1,000 PY; 95% CI, 3.2 to 4.7, respectively). Remarkable was the high incidence in the youngest female age category of 55 to 59 years (7.4/1,000 PY; 95% CI, 4.1 to 12.6). For a 55-year-old man and woman still free of COPD at cohort entry, the risk for the development of COPD over the coming 40 years was 24% and 16%, respectively. CONCLUSION: The overall incidence of COPD in an elderly population is 9.2/1,000 PY, with a remarkably high incidence in the youngest women, suggesting a further shift toward the female sex in the gender distribution of COPD. During their further lives, one of four men and one of six women free of COPD at the age of 55 years will have COPD develop.