Acute exacerbations of chronic obstructive pulmonary disease are associated with decreased CD4+ & CD8+ T cells and increased growth & differentiation factor-15 (GDF-15) in peripheral blood

Single-cell immunophenotyping revealed the association of CD4+ central and CD4+ effector memory T cells linking exacerbating chronic obstructive pulmonary disease and NSCLC

Introduction

Tobacco smoking generates airway inflammation in chronic obstructive pulmonary disease (COPD), and its involvement in the development of lung cancer is still among the leading causes of early death. Therefore, we aimed to have a better understanding of the disbalance in immunoregulation in chronic inflammatory conditions in smoker subjects with stable COPD (stCOPD), exacerbating COPD (exCOPD), or non-small cell lung cancer (NSCLC).

Methods

Smoker controls without chronic illness were recruited as controls. Through extensive mapping of single cells, surface receptor quantification was achieved by single-cell mass cytometry (CyTOF) with 29 antibodies. The CyTOF characterized 14 main immune subsets such as CD4+, CD8+, CD4+/CD8+, CD4-/CD8-, and γ/δ T cells and other subsets such as CD4+ or CD8+ NKT cells, NK cells, B cells, plasmablasts, monocytes, CD11cdim, mDCs, and pDCs. The CD4+ central memory (CM) T cells (CD4+/CD45RA-/CD45RO+/CD197+) and CD4+ effector memory (EM) T cells (CD4+/CD45RA-/CD45RO+/CD197-) were FACS-sorted for RNA-Seq analysis. Plasma samples were assayed by Luminex MAGPIX® for the quantitative measurement of 17 soluble immuno-oncology mediators (BTLA, CD28, CD80, CD27, CD40, CD86, CTLA-4, GITR, GITRL, HVEM, ICOS, LAG-3, PD-1, PD-L1, PD-L2, TIM-3, TLR-2) in the four studied groups.

Results

Our focus was on T-cell-dependent differences in COPD and NSCLC, where peripheral CD4+ central memory and CD4+ effector memory cells showed a significant reduction in exCOPD and CD4+ CM showed elevation in NSCLC. The transcriptome analysis delineated a perfect correlation of differentially expressed genes between exacerbating COPD and NSCLC-derived peripheral CD4+ CM or CD4+ EM cells. The measurement of 17 immuno-oncology soluble mediators revealed a disease-associated phenotype in the peripheral blood of stCOPD, exCOPD, and NSCLC patients.

Discussion

The applied single-cell mass cytometry, the whole transcriptome profiling of peripheral CD4+ memory cells, and the quantification of 17 plasma mediators provided complex data that may contribute to the understanding of the disbalance in immune homeostasis generated or sustained by tobacco smoking in COPD and NSCLC.

Blood Gene Expression and Immune Cell Subtypes Associated with Chronic Obstructive Pulmonary Disease Exacerbations

Rationale: Acute exacerbations of chronic obstructive pulmonary disease (AE-COPDs) are associated with a significant disease burden. Blood immune phenotyping may improve our understanding of a COPD endotype at increased risk of exacerbations. Objective: To determine the relationship between the transcriptome of circulating leukocytes and COPD exacerbations. Methods: Blood RNA sequencing data (n = 3,618) from the COPDGene (Genetic Epidemiology of COPD) study were analyzed. Blood microarray data (n = 646) from the ECLIPSE (Evaluation of COPD Longitudinally to Identify Predictive Surrogate Endpoints) study were used for validation. We tested the association between blood gene expression and AE-COPDs. We imputed the abundance of leukocyte subtypes and tested their association with prospective AE-COPDs. Flow cytometry was performed on blood in SPIROMICS (Subpopulations and Intermediate Outcomes in COPD Study) (n = 127), and activation markers for T cells were tested for association with prospective AE-COPDs. Measurements and Main Results: Exacerbations were reported 4,030 and 2,368 times during follow-up in COPDGene (5.3 ± 1.7 yr) and ECLIPSE (3 yr), respectively. We identified 890, 675, and 3,217 genes associated with a history of AE-COPDs, persistent exacerbations (at least one exacerbation per year), and prospective exacerbation rate, respectively. In COPDGene, the number of prospective exacerbations in patients with COPD (Global Initiative for Chronic Obstructive Lung Disease stage ⩾2) was negatively associated with circulating CD8+ T cells, CD4+ T cells, and resting natural killer cells. The negative association with naive CD4+ T cells was replicated in ECLIPSE. In the flow-cytometry study, an increase in CTLA4 on CD4+ T cells was positively associated with AE-COPDs. Conclusions: Individuals with COPD with lower circulating lymphocyte counts, particularly decreased CD4+ T cells, are more susceptible to AE-COPDs, including persistent exacerbations.

Probabilistic cellular automata modelling of intercellular interactions in airways: complex pattern formation in patients with chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is a highly prevalent lung disease characterized by chronic inflammation and tissue remodeling possibly induced by unusual interactions between fibrocytes and CD8+ T lymphocytes in the peribronchial area. To investigate this phenomenon, we developed a probabilistic cellular automata type model where the two types of cells follow simple local interaction rules taking into account cell death, proliferation, migration and infiltration. We conducted a rigorous mathematical analysis using multiscale experimental data obtained in control and disease conditions to estimate the model's parameters accurately. The simulation of the model is straightforward to implement, and two distinct patterns emerged that we can analyse quantitatively. In particular, we show that the change in fibrocyte density in the COPD condition is mainly the consequence of their infiltration into the lung during exacerbations, suggesting possible explanations for experimental observations in normal and COPD tissue. Our integrated approach that combines a probabilistic cellular automata model and experimental findings will provide further insights into COPD in future studies.

Alterations in circulating mitochondrial signals at hospital admission for COPD exacerbation

BACKGROUND

Chronic obstructive pulmonary disease (COPD) exacerbation (ECOPD) alters the natural course of the disease. To date, only C-reactive protein has been used as a biomarker in ECOPD, but it has important limitations. The mitochondria release peptides (Humanin (HN), FGF-21, GDF-15, MOTS-c and Romo1) under certain metabolic conditions. Here, we aimed to evaluate the pathophysiologic, diagnostic and prognostic value of measuring serum mitochondrial peptides at hospital admission in patients with ECOPD.

METHODS

A total of 51 consecutive patients admitted to our hospital for ECOPD were included and followed for 1 year; in addition, 160 participants with stable COPD from our out-patient clinic were recruited as controls.

RESULTS

Serum FGF-21 (p < .001), MOTS-c (p < .001) and Romo1 (p = .002) levels were lower, and GDF-15 (p < .001) levels were higher, in patients with ECOPD than stable COPD, but no differences were found in HN. In receiver operating characteristic analysis, MOTS-c (AUC 0.744, 95% CI 0.679-0.802, p < .001) and GDF-15 (AUC 0.735, 95% CI 0.670-0.793, p < .001) had the best diagnostic power for ECOPD, with a diagnostic accuracy similar to that of C-RP (AUC 0.796 95% IC 0.735-0.848, p < .001). FGF-21 (AUC 0.700, 95% CI 0.633-0.761, p < .001) and Romo1 (AUC 0.645 95% CI 0.573-0.712, p = .001) had lower diagnostic accuracy. HN levels did not differentiate patients with ECOPD versus stable COPD (p = .557). In Cox regression analysis, HN (HR 2.661, CI95% 1.009-7.016, p = .048) and MOTS-c (HR 3.441, CI95% 1.252-9.297, p = .016) levels exceeding mean levels were independent risk factors for re-admission.

CONCLUSIONS

Most mitochondrial peptides are altered in ECOPD, as compared with stable COPD. MOTS-c and GDF15 levels have a diagnostic accuracy similar to C-RP for ECOPD. HN and MOTS-c independently predict future re-hospitalization.

Associations between serum mitokine levels and outcomes in stable COPD: an observational prospective study

Mitokines (Humanin (HN), GDF15 and FGF21) are produced as a result of mitochondrial dysfunction and may have major roles in chronic inflammation, malnutrition and exercise capacity in people with COPD. Except for GDF15, studies on this subject are lacking. A total of 165 patients with stable COPD and 49 smokers without COPD were enrolled. We assessed their serum mitokine levels and clinical characteristics at baseline. We recorded moderate and severe exacerbation for the next 12 months. Baseline serum HN (p = 0.037) and GDF-15 (p = 0.013) levels were higher in the COPD group. High HN levels were independently associated with a high risk of exacerbation (HRE) (OR 2.798, 95% CI 1.266-6.187, p = 0.011), malnutrition (OR 6.645, 95% CI 1.859-23.749, p = 0.004), and 6MWD (OR 0.995, 95% CI 0.991-0.999, p = 0.008), and future moderate (HR 1.826, 95% CI 1.181-2.822, p = 0.007) and severe exacerbations (HR 3.445, 95% CI 1.357-8.740, p = 0.009). High GDF15 levels were associated with HRE (OR 3.028, 95% CI 1.134-8.083, p = 0.027), 6MWD (OR 0.995, 95% CI 0.990-0.999, p = 0.017) and predicted desaturation in 6MWT (OR 3.999, 95% CI 1.487-10.757, p = 0.006). High FGF21 levels were associated with HRE (OR 2.144, 95% CI 1.000-4.600, p = 0.05), and predicted future severe exacerbation (HR 4.217, 95% CI 1.459-12.193, p = 0.008). The mitokine levels were higher in patients with COPD than smokers without COPD, and were associated with important clinical outcomes such as exercise capacity and COPD exacerbation. Among the mitokines, HN showed the strongest association with COPD and may serve as a future risk biomarker in this disease.Trial registation NCT04449419.

Growth Differentiation Factor-15 as a Biomarker for Sarcopenia in Patients With Chronic Obstructive Pulmonary Disease

Purpose

Sarcopenia is an important factor contributing to comorbidities in patients with chronic obstructive pulmonary disease (COPD) and is an independent risk factor for increased mortality. The diagnostic process for sarcopenia requires specific equipment and specialized training and is difficult procedurally. A previous study found that GDF15 levels are associated with skeletal muscle mass and function in patients with COPD. However, whether circulating GDF15 levels can be used for the prediction of sarcopenia in patients with COPD is unknown.

Methods

This study included 235 patients with stable COPD who were divided into a development set (n = 117) and a validation set (n = 118), and we followed the definition of sarcopenia as defined by the guidelines from the Asian Working Group for Sarcopenia. Serum concentrations of GDF15 were measured using an enzyme-linked immunosorbent assay (ELISA), and construction of a nomogram and decision curve analysis were performed using the R package “rms.”

Results

In this study, serum GDF15 levels were negatively associated with skeletal muscle mass (r = –0.204, p = 0.031), handgrip strength (r = –0.274, p = 0.004), quadriceps strength (r = –0.269, p = 0.029), and the thickness (r = –0.338, p < 0.001) and area (r = –0.335, p < 0.001) of the rectus femoris muscle in patients with COPD. Furthermore, the serum levels of GDF15 in patients with sarcopenia were significantly higher than those in controls. Importantly, serum levels of GDF15 could effectively predict sarcopenia in patients with COPD based on the development set (AUC = 0.827) and validation set (AUC = 0.801). Finally, a nomogram model based on serum GDF15 levels and clinical features showed good predictive ability (AUC > 0.89) in the development and validation sets.

Conclusion

Serum GDF15 levels could be used to accurately and easily evaluate sarcopenia in patients with COPD.

Role of CD4+ T and CD8+ T Lymphocytes-Mediated Cellular Immunity in Pathogenesis of Chronic Obstructive Pulmonary Disease

This work was to explore the changes of T lymphocyte subsets in peripheral blood of patients with acute exacerbation of chronic obstructive pulmonary disease (COPD) (AECOPD) and the role of cellular immunity mediated in the disease process. Eighty-six patients with AECOPD who visited Qingdao Hiser Medical Center from June 2020 to December 2021 and 30 healthy people (controls) who underwent health examination in the same period were selected. The differences of pulmonary function (PF), arterial blood gas (ABG), blood routine inflammatory indexes, T lymphocyte and T lymphocyte subsets were compared between the two groups, and the correlation between T lymphocyte subsets and each index was analyzed. There were clear differences in PF, ABG, and PB inflammation indexes between AECOPD patients and the controls (P <0.05). Compared with the controls, the CD₄⁺ and CD₄⁺/CD₈⁺ ratio in PB of AECOPD group were obviously decreased, and the CD₈⁺ level was clearly increased (P <0.05); Th1 of CD₄⁺ cell subsets and Tc1 of CD₈⁺ cell subsets were significantly increased, while Th2 of CD₄⁺ cell subsets and Tc2 of CD₈⁺ cell subsets were obviously decreased (P <0.05). However, CD4⁺ was significantly positively correlated with lung function indexes, and significantly negatively correlated with neutrophils/lymphocytes and high-sensitivity C-reactive protein (P <0.05) and significantly positively correlated with Hs-CRP (P <0.05). In summary, CD4+ and CD8⁺ T lymphocytes were involved in the occurrence and occurrence of AECOPD, the decrease of CD4⁺ and the increase of CD8⁺ may promote the deterioration of COPD.

Low Eosinophil Phenotype Predicts Noninvasive Mechanical Ventilation Use in Patients with Hospitalized Exacerbations of COPD

Rationale

Objective

Methods

Results

Conclusion

Effect of Autoimmune Cell Therapy on Immune Cell Content in Patients with COPD: A Randomized Controlled Trial

Objective

To explore the effect of autoimmune cell therapy on immune cells in patients with chronic obstructive pulmonary disease (COPD) and to provide a reference for clinical treatment of COPD.

Methods

Sixty patients with stable COPD were randomly divided into control group and treatment group (n = 30). The control group was given conventional treatment, and the treatment group was given one autoimmune cell therapy on the basis of conventional treatment. The serum levels of CD3+ T cells, CD4+ T cells, CD8+ cells, B cells, and NK cells in the peripheral blood were detected by flow cytometry. Possible adverse reactions were detected at any time during treatment.

Results

There were no significant differences in the contents of CD3+ T cells, CD4+ T cells, CD8+ cells, B cells, and NK cells in the serum of the control group (P > 0.05). Compared with before treatment, the contents of CD3+ T cells, CD4+ T cells, CD8+ cells, B cells, and NK cells in the serum of the treatment group were significantly increased (P < 0.05). The ratio of CD4 + /CD8+ T cells in both control and treatment groups did not change significantly during treatment (P > 0.05). There were no significant differences in serum CD3+ T cells, CD4+ T cells, CD8+ cells, B cells, and NK cells in the treatment group at 30 days and 90 days after treatment (P > 0.05), but they were significantly higher than those in the control group (P < 0.05).

Conclusion

Autoimmune cell therapy can significantly increase the level of immune cells in the body and can be maintained for a long period of time, which has certain clinical benefits for recurrent respiratory tract infections and acute exacerbation in patients with COPD.

Characterization of atherosclerotic plaques in blood vessels with low oxygenated blood and blood pressure (Pulmonary trunk): role of growth differentiation factor-15 (GDF-15)

BACKGROUND

Growth differentiation factor (GDF)-15 is linked to inflammation, cancer, and atherosclerosis. GDF-15 is expressed in most tissues but is extremely induced under pathological conditions. Elevated serum levels are suggested as a risk factor and a marker for cardiovascular diseases. However, the cellular sources and the effects of GDF-15 on the cardiovascular system have not been completely elucidated including progression, and morphology of atherosclerotic plaques. Thus, this work aimed to characterize the influence of GDF-15 deficiency on the morphology of atherosclerotic plaques in blood vessels with low-oxygen blood and low blood pressure as the pulmonary trunk (PT), in hypercholesterolemic ApoE-/- mice.

METHODS

GDF-15-/- ApoE-/- mice were generated by crossbreeding of ApoE-/-- and GDF-15-/- mice. After feeding a cholesterol-enriched diet (CED) for 20 weeks, samples of the brachiocephalic trunk (BT) and PT were dissected and lumen stenosis (LS) was measured. Furthermore, changes in the cellularity of the PT, amounts of apoptosis-, autophagy-, inflammation- and proliferation-relevant proteins were immunohisto-morphometrically analyzed. Additionally, we examined an atherosclerotic plaque in a human post mortem sample of the pulmonary artery.

RESULTS

After CED the body weight of GDF-15-/-ApoE-/- was 22.9% higher than ApoE-/-. Double knockout mice showed also an 35.3% increase of plasma triglyceride levels, whereas plasma cholesterol was similar in both genotypes. LS in the BT and PT of GDF-15-/-ApoE-/- mice was significantly reduced by 19.0% and by 6.7% compared to ApoE-/-. Comparing LS in PT and BT of the same genotype revealed a significant 38.8% (ApoE-/-) or 26.4% (GDF-15-/-ApoE-/-) lower LS in the PT. Immunohistomorphometry of atherosclerotic lesions in PT of GDF-15-/-ApoE-/- revealed significantly increased levels (39.8% and 7.3%) of CD68 + macrophages (MΦ) and α-actin + smooth muscle cells than in ApoE-/-. The density of TUNEL + , apoptotic cells was significantly (32.9%) higher in plaques of PT of GDF-15-/-ApoE-/- than in ApoE-/-. Analysis of atherosclerotic lesion of a human pulmonary artery showed sm-α-actin, CD68+, TUNEL+, Ki67+, and APG5L/ATG+ cells as observed in PT. COX-2+ and IL-6+ immunoreactivities were predominantly located in endothelial cells and subendothelial space. In BT and PT of GDF15-/-ApoE-/- mice the necrotic area was 10% and 6.5% lower than in ApoE-/-. In BT and PT of GDF15-/-ApoE-/- we found 40% and 57% less unstable plaques than ApoE-/- mice.

CONCLUSIONS

Atherosclerotic lesions occur in both, BT and PT, however, the size is smaller in PT, possibly due to the effect of the low-oxygen blood and/or lower blood pressure. GDF-15 is involved in atherosclerotic processes in BT and PT, although different mechanisms (e.g. apoptosis) in these two vessels seem to exist.

Plasma GDF-15 concentration is not elevated in open-angle glaucoma

Aim

Recently, the level of growth differentiation factor 15 (GDF-15) in blood, was proposed as biomarker to detect mitochondrial dysfunction. In the current study, we evaluate this biomarker in open-angle glaucoma (OAG), as there is increasing evidence that mitochondrial dysfunction plays a role in the pathophysiology of this disease.

Methods

Plasma GDF-15 concentrations were measured with ELISA in 200 OAG patients and 61 age-matched controls (cataract without glaucoma). The OAG patient group consisted of high tension glaucoma (HTG; n = 162) and normal tension glaucoma (NTG; n = 38). Groups were compared using the Kruskal-Wallis nonparametric test with Dunn’s multiple comparison post-hoc correction. GDF-15 concentration was corrected for confounders identified with forward linear regression models.

Results

Before correcting for confounders, median plasma GDF-15 levels was significantly lower in the combined OAG group (p = 0.04), but not when analysing HTG and NTG patients separately. Forward linear regression analysis showed that age, gender, smoking and systemic hypertension were significant confounders affecting GDF-15 levels. After correction for these confounders, GDF-15 levels in OAG patients were no longer significantly different from controls. Subgroup analysis of the glaucoma patients did not show a correlation between disease severity and plasma GDF-15, but did reveal that for NTG patients, intake of dietary supplements, which potentially improve mitochondrial function, correlated with lower plasma GDF-15.

Conclusion

The present study suggests that plasma GDF-15 is not suited as biomarker of mitochondrial dysfunction in OAG patients.

The Role of Human Leukocyte Antigen-DR in Regulatory T Cells in Patients with Virus-Induced Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Background

This study assessed the role of different immune phenotypes of T cells in virus-induced acute exacerbation of chronic obstructive pulmonary disease (AECOPD).

Material/Methods

The study involved 103 participants, including individuals with virus-induced AECOPD (n=32), non-virus-induced AECOPD (n=31), and stable COPD (n=20) and individuals who were healthy smokers (n=20). The immune phenotypes of T cells in peripheral blood were evaluated via flow cytometry analysis, and the differences were analyzed.

Results

Patients with virus-induced AECOPD (virus group) had a higher COPD assessment test score on admission than those in the group with non-virus-induced AECOPD (nonvirus group; 25.6±3.8 vs 21.9±4.8, P=0.045). A lower CD4⁺ human leukocyte antigen-DR (HLA-DR)⁺ frequency was found in the peripheral blood of the virus group compared with the nonvirus group (2.2 vs 4.2, P=0.015), and the frequency of CD4⁺ CD25^high CD127^low HLA-DR⁺ in CD4⁺ in the virus group was lower than in the nonvirus group (1.1 vs 3.6, P=0.011). The CD3⁺, CD4⁺, CD8⁺, CD4⁺ central memory T cell, CD4⁺ effector memory T cell (Tem), CD4⁺ end-stage T cell, and CD8⁺ Tem levels in lymphocytes of peripheral blood were lower in exacerbation groups relative to those in the stable COPD and healthy smoking groups, but similar between exacerbation groups. Similar frequencies and levels of T cells between different stagings of COPD were also identified.

Conclusions

The expression of HLA-DR on the cell surface of CD4⁺ regulatory T cells (Tregs) was lower in the peripheral blood of patients with virus-induced AECOPD. The expression of HLA-DR in CD4⁺ Tregs suggested the effect of respiratory viruses on adaptive immunity of patients with AECOPD to some extent.

Th17 cells are involved in mouse chronic obstructive pulmonary disease complicated with invasive pulmonary aspergillosis

BACKGROUND

The incidence of chronic obstructive pulmonary disease (COPD) complicated with invasive pulmonary aspergillosis (IPA) has increased in the last two decades. The mechanism underpinning susceptibility to and high mortality of COPD complicated with IPA is unclear, and the role of T helper cells 17 (Th17 cells) in the compound disease remains unknown. Therefore, this study aimed to assess the function of Th17 cells in COPD combined with IPA.

METHODS

COPD, IPA, and COPD+IPA mouse models were established in male wild type C57/BL6 mice. The amounts of Th17 cells and retinoic acid-related orphan receptors γt (RORγt) were tested by flow cytometry. Then, serum interleukin (IL)-17 and IL-23 levels were detected by enzyme-linked immunosorbent assay (ELISA) in the control, COPD, IPA and COPD+IPA groups. In addition, COPD+IPA was induced in IL-17 knockout (KO) mice, for determining the role of Th17 cells in COPD+IPA.

RESULTS

Compared with the COPD group, the COPD+IPA group showed higher amounts of blood RORγt ([35.09 ± 16.12]% vs. [17.92 ± 4.91]%, P = 0.02) and serum IL-17 (17.96 ± 9.59 pg/mL vs. 8.05 ± 4.44 pg/mL, P = 0.02), but blood ([5.18 ± 1.09]% vs. [4.15 ± 0.87]%, P = 0.28) and lung levels of Th17 cells ([1.98 ± 0.83]% vs. [2.03 ± 0.98]%, P = 0.91), lung levels of RORγt ([9.58 ± 6.93]% vs. [9.63 ± 5.98]%, P = 0.49) and serum IL-23 (51.55 ± 27.82 pg/mL vs. 68.70 ± 15.20 pg/mL, P = 0.15) showed no significant differences. Compared with the IPA group, the COPD+IPA group displayed lower amounts of blood ([5.18 ± 1.09]% vs. [9.21 ± 3.56]%, P = 0.01) and lung Th17 cells ([1.98 ± 0.83]% vs. [6.29 ± 1.11]%, P = 0.01) and serum IL-23 (51.55 ± 27.82 pg/mL vs. 154.90 ± 64.60 pg/mL, P = 0.01) and IL-17 (17.96 ± 9.59 pg/mL vs. 39.81 ± 22.37 pg/mL, P = 0.02), while comparable blood ([35.09 ± 16.12]% vs. [29.86 ± 15.42]%, P = 0.25) and lung levels of RORγt ([9.58 ± 6.93]% vs. [15.10 ± 2.95]%, P = 0.18) were found in these two groups. Finally, Aspergillus load in IL-17 KO COPD+IPA mice was almost 2 times that of COPD+IPA mice (1,851,687.69 ± 944,480.43 vs. 892,958.10 ± 686,808.80, t = 2.32, P = 0.02).

CONCLUSION

These findings indicate that Th17 cells might be involved in the pathogenesis of COPD combined with IPA, with IL-17 likely playing an antifungal role.

The role of CD8 + T lymphocytes in chronic obstructive pulmonary disease: a systematic review

OBJECTIVE AND DESIGN

This systematic review aims to establish the role of CD8 + T lymphocytes in COPD.

METHODS

Forty-eight papers published in the last 15 years were identified for inclusion.

RESULTS

CD8 + T-cells are increased in the lungs of patients with COPD (17 studies, 16 positive) whereas in the circulation, findings were inconclusive. Activation of CD8 + T-cells was enhanced in lungs (four studies, three positive) but cell phenotype was unclear. There was substantial evidence of a higher proportion of type 1 CD8 + (Tc1) cells in COPD (11 studies, 9 positive), though the population of type 2 (Tc2) cells was also increased (5 studies, 4 positive). CD8 + T-cells in COPD exhibited greater expression of cytotoxic proteins (five studies, five positive). Studies assessed a variety of questions so evidence was insufficient to draw firm conclusions. The role of CD8 + T-cells at acute exacerbation of COPD and also their contribution to alveolar destruction can only be hypothesised at this stage.

CONCLUSIONS

Not only is the number of CD8 + T-cells increased in COPD, these cells have increased capacity to exert effector functions and are likely to contribute to disease pathogenesis. Several mechanisms highlighted show promise for future investigation to consolidate current knowledge.

Mitochondria, immunosenescence and inflammaging: a role for mitokines?

A global reshaping of the immune responses occurs with ageing, indicated as immunosenescence, where mitochondria and mitochondrial metabolism play an important role. However, much less is known about the role of mitochondrial stress response in this reshaping and in particular of the molecules induced by such response, collectively indicated as mitokines. In this review, we summarize the current knowledge on the role of mitokines in modulating immune response and inflammation focusing on GDF15, FGF21 and humanin and their possible involvement in the chronic age-related low-grade inflammation dubbed inflammaging. Although many aspects of their biology are still controversial, available data suggest that these mitokines have an anti-inflammatory role and increase with age. Therefore, we hypothesize that they can be considered part of an adaptive and integrated immune-metabolic mechanism activated by mitochondrial dysfunction that acts within the framework of a larger anti-inflammatory network aimed at controlling both acute inflammation and inflammaging.

Growth/Differentiation Factor-15 (GDF-15): From Biomarker to Novel Targetable Immune Checkpoint

Growth/differentiation factor-15 (GDF-15), also named macrophage inhibitory cytokine-1, is a divergent member of the transforming growth factor β superfamily. While physiological expression is barely detectable in most somatic tissues in humans, GDF-15 is abundant in placenta. Elsewhere, GDF-15 is often induced under stress conditions, seemingly to maintain cell and tissue homeostasis; however, a moderate increase in GDF-15 blood levels is observed with age. Highly elevated GDF-15 levels are mostly linked to pathological conditions including inflammation, myocardial ischemia, and notably cancer. GDF-15 has thus been widely explored as a biomarker for disease prognosis. Mechanistically, induction of anorexia via the brainstem-restricted GDF-15 receptor GFRAL (glial cell-derived neurotrophic factor [GDNF] family receptor α-like) is well-documented. GDF-15 and GFRAL have thus become attractive targets for metabolic intervention. Still, several GDF-15 mediated effects (including its physiological role in pregnancy) are difficult to explain via the described pathway. Hence, there is a clear need to better understand non-metabolic effects of GDF-15. With particular emphasis on its immunomodulatory potential this review discusses the roles of GDF-15 in pregnancy and in pathological conditions including myocardial infarction, autoimmune disease, and specifically cancer. Importantly, the strong predictive value of GDF-15 as biomarker may plausibly be linked to its immune-regulatory function. The described associations and mechanistic data support the hypothesis that GDF-15 acts as immune checkpoint and is thus an emerging target for cancer immunotherapy.

Practical recommendations for the use of beta-blockers in chronic obstructive pulmonary disease

INTRODUCTION

Controversies regarding the use of beta-blocker in chronic obstructive pulmonary disease (COPD) have been longstanding and based on inconsistent data. COPD and cardiovascular disease have many shared risk factors and potentially overlapping pathophysiologic mechanisms. Beta-blockers, a mainstay of treatment in ischemic heart disease, congestive heart failure, and cardiac arrhythmia, remain underutilized in COPD patients despite considerable evidence of safety. Furthermore, observational studies indicated the potential benefits of beta-blockers in COPD via a variety of possible mechanisms. Recently, a randomized controlled trial of metoprolol versus placebo failed to show a reduction in COPD exacerbation risk in subjects with moderate to severe COPD and no absolute indication for beta-blocker use.

AREAS COVERED

Physiology of beta-adrenergic receptors, links between COPD and cardiovascular disease, and the role of beta-blockers in COPD management are discussed.

EXPERT COMMENTARY

Beta-blockers should not be used to treat COPD patients who do not have conditions with clear guideline-directed recommendations for their use. Vigilance is recommended in prescribing these medications for indications where another drug class could be utilized.

GDF-15 in Pulmonary and Critical Care Medicine

GDF-15 (growth differentiation factor 15) acts both as a stress-induced cytokine with diverse actions at different body sites and as a cell-autonomous regulator linked to cellular senescence and apoptosis. For multiple reasons, this divergent transforming growth factor-β molecular superfamily member should be better known to pulmonary researchers and clinicians. In ambulatory individuals, GDF-15 concentrations in peripheral blood are an established predictive biomarker of all-cause mortality and of adverse cardiovascular events. Concentrations upon admission of critically ill patients (without or with sepsis) correlate with organ dysfunction and independently predict short- and long-term mortality risk. GDF-15 is a major downstream mediator of p53 activation, but it can also be induced independently of p53, notably by nonsteroidal antiinflammatory agents. GDF-15 blood concentrations are markedly elevated in adults and children with pulmonary hypertension. Concentrations are also increased in chronic obstructive pulmonary disease, in which they contribute to mucus hypersecretion, airway epithelial cell senescence, and impaired antiviral defenses, which together with murine data support a role for GDF-15 in chronic obstructive pulmonary disease pathogenesis and progression. This review summarizes biological and clinical data on GDF-15 relevant to pulmonary and critical care medicine. We highlight the recent discovery of a central nervous system receptor for GDF-15, GFRAL (glial cell line-derived neurotrophic factor family receptor-α-like), an important advance with potential for novel treatments for obesity and cachexia. We also describe limitations and controversies in the existing literature, and we delineate research questions that must be addressed to determine whether GDF-15 can be therapeutically manipulated in other clinical settings.

GDF15 is an epithelial-derived biomarker of idiopathic pulmonary fibrosis

Idiopathic pulmonary fibrosis (IPF) is the most common and devastating of the interstitial lung diseases. Epithelial dysfunction is thought to play a prominent role in disease pathology, and we sought to characterize secreted signals that may contribute to disease pathology. Transcriptional profiling of senescent type II alveolar epithelial cells from mice with epithelial-specific telomere dysfunction identified the transforming growth factor-β family member, growth and differentiation factor 15 (Gdf15), as the most significantly upregulated secreted protein. Gdf15 expression is induced in response to telomere dysfunction and bleomycin challenge in mice. Gdf15 mRNA is expressed by lung epithelial cells, and protein can be detected in peripheral blood and bronchoalveolar lavage following bleomycin challenge in mice. In patients with IPF, GDF15 mRNA expression in lung tissue is significantly increased and correlates with pulmonary function. Single-cell RNA sequencing of human lungs identifies epithelial cells as the primary source of GDF15, and circulating concentrations of GDF15 are markedly elevated and correlate with disease severity and survival in multiple independent cohorts. Our findings suggest that GDF15 is an epithelial-derived secreted protein that may be a useful biomarker of epithelial stress and identifies IPF patients with poor outcomes.

Peripheral blood CD4+ T cell populations by CD25 and Foxp3 expression as a potential biomarker: reflecting inflammatory activity in chronic obstructive pulmonary disease

Background

The temporally dynamic changes of CD25 and Foxp3 expression in CD4+ T cells are initiated by T cell receptor (TCR) signals strength or frequency. There is a deficiency of peripheral markers for assessing COPD activity, and the current study was conducted to explore whether peripheral CD4+ T cell populations based on CD25 and Foxp3 expression could serve as an indicator for COPD inflammatory activity.

Methods

The distribution and phenotypic characteristics of CD4+CD25±Foxp3± T cells from peripheral blood in different populations were determined by flow cytometry. The model for the differentiation of CD4+ T cells populations by CD25 and Foxp3 expression was explored in vitro.

Results

The frequencies of peripheral CD4+CD25+Foxp3- T cells and CD4+CD25+Foxp3+ T cells were increased in AECOPD patients, whereas the frequency of CD4+CD25-Foxp3+ T cells was increased in SCOPD patients without receiving systemic treatment. Phenotypic analysis revealed that CD4+CD25+Foxp3- T cells, CD4+CD25+Foxp3+ T cells and CD4+CD25-Foxp3+ T cells had received antigenic stimulation and resembled central memory or effector memory T cells. The differentiation of CD4+ T cells populations by CD25 and Foxp3 expression was dictated by TCR signals. The paired study indicated that the frequencies of CD4+CD25+Foxp3- T cells, CD4+CD25+Foxp3+ T cells and CD4+CD25- Foxp3+ T cells were decreased while the frequency of CD4+CD25-Foxp3- T cells were increased in the same patients from AECOPD to convalescence.

Conclusions

Collectively, we propose that the dynamic changes of CD4+ T cell populations by CD25 and Foxp3 expression could function as potential biomarkers for reflecting inflammatory activity in COPD.

Inference of Cellular Immune Environments in Sputum and Peripheral Blood Associated with Acute Exacerbations of COPD

Introduction

Chronic obstructive pulmonary disease (COPD) is the fourth leading cause of death in the United States, with high associated costs. Most of the cost burden results from acute exacerbations of COPD (AE-COPD), events associated with heightened symptoms and mortality. Cellular mechanisms underlying AE-COPD are poorly understood, likely because they arise from dysregulation of complex immune networks across multiple tissue compartments.

Methods

To gain systems-level insight into cellular environments relevant to exacerbation, we applied data-driven modeling approaches to measurements of immune factors (cytokines and flow cytometry) measured previously in two different human tissue environments (sputum and peripheral blood) during the stable and exacerbated state.

Results

Using partial least squares discriminant analysis, we identified a unique signature of cytokines in serum that differentiated stable and AE-COPD better than individual measurements. Furthermore, we found that models integrating data across tissue compartments (serum and sputum) trended towards being more accurate. The resulting paracrine signature defining AE-COPD events combined elevations of proteins associated with cell adhesion (sVCAM-1, sICAM-1) and increased levels of neutrophils and dendritic cells in blood with elevated chemoattractants (IP-10 and MCP-2) in sputum.

Conclusions

Our results supported a new hypothesis that AE-COPD is driven by immune cell trafficking into the lung, which requires expression of cell adhesion molecules and raised levels of innate immune cells in blood, with parallel upregulated expression of specific chemokines in pulmonary tissue. Overall, this work serves as a proof-of-concept for using data-driven modeling approaches to generate new insights into cellular processes involved in complex pulmonary diseases.

Immunodeficiency in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Chronic obstructive pulmonary disease (COPD), characterized by progressive airway inflammation and irreversible airflow limitation, leads to serious decline in life quality. The acute exacerbation of COPD (AECOPD) results in high healthcare costs as well as a significant mortality rate. The most common cause of acute exacerbation is infection. Immune deficiency, which induces dysfunction of anti-infection, plays an important role in the pathogenesis of acute exacerbation. As described in this review, the immune dysfunction in patients with AECOPD can be a major focus of efforts to therapeutic strategy.

Muscle wasting in the presence of disease, why is it so variable?

Skeletal muscle wasting is a common clinical feature of many chronic diseases and also occurs in response to single acute events. The accompanying loss of strength can lead to significant disability, increased care needs and have profound negative effects on quality of life. As muscle is the most abundant source of amino acids in the body, it appears to function as a buffer for fuel and substrates that can be used to repair damage elsewhere and to feed the immune system. In essence, the fundamentals of muscle wasting are simple: less muscle is made than is broken down. However, although well-described mechanisms modulate muscle protein turnover, significant individual differences in the amount of muscle lost in the presence of a given severity of disease complicate the understanding of underlying mechanisms and suggest that individuals have different sensitivities to signals for muscle loss. Furthermore, the rate at which muscle protein is turned over under normal conditions means that clinically significant muscle loss can occur with changes in the rate of protein synthesis and/or breakdown that are too small to be measurable. Consequently, the changes in expression of factors regulating muscle turnover required to cause a decline in muscle mass are small and, except in cases of rapid wasting, there is no consistent pattern of change in the expression of factors that regulate muscle mass. MicroRNAs are fine tuners of cell phenotype and are therefore ideally suited to cause the subtle changes in proteome required to tilt the balance between synthesis and degradation in a way that causes clinically significant wasting. Herein we present a model in which muscle loss as a consequence of disease in non-muscle tissue is modulated by a set of microRNAs, the muscle expression of which is associated with severity of disease in the non-muscle tissue. These microRNAs alter fundamental biological processes including the synthesis of ribosomes and mitochondria leading to reduced protein synthesis and increased protein breakdown, thereby freeing amino acids from the muscle. We argue that the variability in muscle loss observed in the human population arises from at least two sources. The first is from pre-existing or disease-induced variation in the expression of microRNAs controlling the sensitivity of muscle to the atrophic signal and the second is from the expression of microRNAs from imprinted loci (i.e. only expressed from the maternally or paternally inherited allele) and may control the rate of myonuclear recruitment. In the absence of disease, these factors do not correlate with muscle mass, since there is no challenge to the established balance. However, in the presence of such a challenge, these microRNAs determine the rate of decline for a given disease severity. Together these mechanisms provide novel insight into the loss of muscle mass and its variation in the human population. The involvement of imprinted loci also suggests that genes that regulate early development also contribute to the ability of individuals to resist muscle loss in response to disease.

Pulmonary Embolism in Patients with Acute Exacerbation of Chronic Obstructive Pulmonary Disease

Objective

In most countries, nearly 6% of the adults are suffering from chronic obstructive pulmonary disease (COPD), which puts a huge economic burden on the society. Moreover, COPD has been considered as an independent risk factor for pulmonary embolism (PE). In this review, we summarized the existing evidence that demonstrates the associations between COPD exacerbation and PE from various aspects, including epidemiology, pathophysiological changes, risk factors, clinical features, management, and prognosis.

Data Sources

We searched the terms "chronic obstructive pulmonary disease," "pulmonary embolism," "exacerbations," and "thromboembolic" in PubMed database and collected the results up to April 2018. The language was limited to English.

Study Selection

We thoroughly examined the titles and abstracts of all studies that met our search strategy. The data from prospective studies, meta-analyses, retrospective studies, and recent reviews were selected for preparing this review.

Results

The prevalence of PE in patients with COPD exacerbation varied a lot among different studies, mainly due to the variations in race, sample size, study design, research setting, and enrollment criteria. Overall, whites and African Americans showed significantly higher prevalence of PE than Asian people, and the hospitalized patients showed higher prevalence of PE compared to those who were evaluated in emergency department. PE is easily overlooked in patients with COPD exacerbation due to the similar clinical symptoms. However, several factors have been identified to contribute to the increased risk of PE during COPD exacerbation. Obesity and lower limb asymmetry were described as independent predictors for PE. Moreover, due to the high risk of PE, thromboprophylaxis has been used as an important treatment for hospitalized patients with COPD exacerbation.

Conclusions

According to the previous studies, COPD patients with PE experienced an increased risk of death and prolonged length of hospital stay. Therefore, the thromboembolic risk in patients with acute exacerbation of COPD, especially in the hospitalized patients, should carefully be evaluated.

Lung Dendritic Cells Drive Natural Killer Cytotoxicity in Chronic Obstructive Pulmonary Disease via IL-15Rα

RATIONALE

Lung natural killer cells (NKs) kill a greater percentage of autologous lung parenchymal cells in chronic obstructive pulmonary disease (COPD) than in nonobstructed smokers. To become cytotoxic, NKs require priming, typically by dendritic cells (DCs), but whether priming occurs in the lungs in COPD is unknown.

METHODS

We used lung tissue and in some cases peripheral blood from patients undergoing clinically indicated resections to determine in vitro killing of CD326+ lung epithelial cells by isolated lung CD56+ NKs. We also measured the cytotoxicity of unprimed blood NKs after preincubation with lung DCs. To investigate mechanisms of DC-mediated priming, we used murine models of COPD induced by cigarette smoke (CS) exposure or by polymeric immunoglobulin receptor (pIgR) deficiency, and blocked IL-15Rα (IL-15 receptor α subunit) trans-presentation by genetic and antibody approaches.

RESULTS

Human lung NKs killed isolated autologous lung epithelial cells; cytotoxicity was increased (P = 0.0001) in COPD, relative to smokers without obstruction. Similarly, increased lung NK cytotoxicity compared with control subjects was observed in CS-exposed mice and pIgR-/- mice. Blood NKs both from smokers without obstruction and subjects with COPD showed minimal epithelial cell killing, but in COPD, preincubation with lung DCs increased cytotoxicity. NKs were primed by CS-exposed murine DCs in vitro and in vivo. Inhibiting IL-15Rα trans-presentation eliminated NK priming both by murine CS-exposed DCs and by lung DCs from subjects with COPD.

CONCLUSIONS

Heightened NK cytotoxicity against lung epithelial cells in COPD results primarily from lung DC-mediated priming via IL-15 trans-presentation on IL-15Rα. Future studies are required to test whether increased NK cytotoxicity contributes to COPD pathogenesis.

Prediction of microRNA and gene target from an integrated network in chronic obstructive pulmonary disease based on canonical correlation analysis

BACKGROUND:

Chronic obstructive pulmonary disease (COPD) is a complex disorder with a high mortality. The pathophysiology of COPD has not been characterized till date.

OBJECTIVE:

To identify COPD-related biomarkers by a bioinformatics analysis.

METHODS:

Here, we conducted the canonical correlation analysis to extract the potential COPD-related miRNAs and mRNAs based on the miRNA-mRNA dual expression profiling data. After identifying miRNAs and mRNAs related to COPD, we constructed an interaction network by integrating three validated miRNA-target sources. Then we expanded the network by adding miRNA-mRNA pairs, which were identified by Spearman rank correlation test. For miRNAs involved in the network, we further performed the Gene Ontology (GO) functional enrichment analysis of their targets. To validate COPD-related mRNAs involved in the network, we performed receiver operating characteristic (ROC) curve analysis and Support Vector Machine (SVM) classification on only those mRNAs that overlapped with COPD-related mRNAs of Online Mendelian Inheritance in Man (OMIM) database.

RESULTS:

The results indicate that some identified miRNAs and their targets in the constructed network might be potential biomarkers of COPD.

CONCLUSIONS:

Our study helps us to predict the potential risk biomarkers of COPD, and it can certainly help in further elucidating the genetic etiology of COPD.

IL-17A and GDF15 are able to induce epithelial-mesenchymal transition of lung epithelial cells in response to cigarette smoke

Smoking is one of the primary causes of chronic obstructive pulmonary disease (COPD). Sustained active epithelial-mesenchymal transition (EMT) in COPD may explain the core pathophysiology of airway fibrosis and why lung cancer is so common among smokers. Interleukin (IL)-17A and growth/differentiation factor (GDF)15 have been reported to be biomarkers of COPD; however, the role of IL-17A and GDF15 in EMT remains unclear. The aim of the present study was to investigate the role of IL-17A and GDF15 in the pathogenesis of COPD. It was demonstrated that IL-17A and GDF15 are upregulated in patients with COPD, particularly those with a history of smoking. The results also revealed that IL-17A and GDF15 expression was negatively correlated with the epithelial marker epithelial-cadherin and positively correlated with the mesenchymal marker vimentin. Furthermore, treatment with cigarette smoke extract or IL-17A induced GDF15 expression. Combined treatment with IL-17A and GDF15 induced EMT in human small epithelial HSAEpiC cells in vitro. Collectively, the results of the present study suggest that IL-17A and GDF15-induced EMT serves an important role in the pathology of COPD.

Overproduction of growth differentiation factor 15 promotes human rhinovirus infection and virus-induced inflammation in the lung

Human rhinovirus (HRV) is the most common virus contributing to acute exacerbations of chronic obstructive pulmonary disease (COPD) nearly year round, but the mechanisms have not been well elucidated. Recent clinical studies suggest that high levels of growth differentiation factor 15 (GDF15) protein in the blood are associated with an increased yearly rate of all-cause COPD exacerbations. Therefore, in the current study, we investigated whether GDF15 promotes HRV infection and virus-induced lung inflammation. We first examined the role of GDF15 in regulating host defense and HRV-induced inflammation using human GDF15 transgenic mice and cultured human GDF15 transgenic mouse tracheal epithelial cells. Next, we determined the effect of GDF15 on viral replication, antiviral responses, and inflammation in human airway epithelial cells with GDF15 knockdown and HRV infection. Finally, we explored the signaling pathways involved in airway epithelial responses to HRV infection in the context of GDF15. Human GDF15 protein overexpression in mice led to exaggerated inflammatory responses to HRV, increased infectious particle release, and decreased IFN-λ2/3 (IL-28A/B) mRNA expression in the lung. Moreover, GDF15 facilitated HRV replication and inflammation via inhibiting IFN-λ1/IL-29 protein production in human airway epithelial cells. Lastly, Smad1 cooperated with interferon regulatory factor 7 (IRF7) to regulate airway epithelial responses to HRV infection partly via GDF15 signaling. Our results reveal a novel function of GDF15 in promoting lung HRV infection and virus-induced inflammation, which may be a new mechanism for the increased susceptibility and severity of respiratory viral (i.e., HRV) infection in cigarette smoke-exposed airways with GDF15 overproduction.

Severity of COPD and its relationship with IL-10

BACKGROUND

The present study was designed to compare inflammatory and metabolic responses according to severity of airflow among patients with COPD and to verify the relationship between pulmonary function, body composition, metabolic and inflammatory profile.

METHODS

Fifty-one patients with mild to very severe COPD were recruited and divided according lung function in Mild-moderate (GOLD 1-2) n= 21; Severe (GOLD 3) n=25 and Very severe (GOLD 4) n=5. Patients were submitted to assessments of lung function (spirometry), functional exercise capacity (6-min walk test), body composition (Octopolar bioelectrical impedance), metabolic profile (glucose, triglycerides, total cholesterol, HDL-cholesterol and albumin (colorimetric assay)) and inflammatory profile (cytokines: IL-6, IL-10, TNF-α and IL-15 (ELISA)).

RESULTS

We found that patients in GOLD 3 group had lower levels of IL-10, triglycerides, visceral fat area, and higher IL-6 and IL-6/IL-10 ratio when compared to GOLD 1-2 patients. Additionally, GOLD 1-2 group presented negative correlation between TNF-α and HDL cholesterol (p= .01) and positive correlation between IL-15 and FEV₁/FVC (p=.01), while GOLD 3 group showed positive correlation between IL-6 and IL-10 (p< .01), IL-6 and total cholesterol (p<.01) and negative correlation between IL-10 and HDL-cholesterol (p=.01).

CONCLUSION

Our findings suggest that patients with severe COPD can exhibit compromised "inflammatory status", characterized by higher IL6, IL-6/IL-10 ratio and lower IL-10 concentration. Furthermore, IL-10 seems to be an interesting cytokine to be investigated in this kind of patients.

Elevated GDF-15 contributes to pulmonary inflammation upon cigarette smoke exposure

The molecular mechanisms underlying the pathogenesis of chronic obstructive pulmonary disease (COPD) are still unclear, however signaling pathways associated with lung development, such as the transforming growth factor (TGF)-β superfamily, could be implicated in COPD. Growth differentiation factor (GDF)-15, a member of the TGF-β superfamily, is involved in inflammation, mucus secretion, and cachexia. We analyzed the pulmonary expression of GDF-15 in smokers and patients with COPD, in cigarette smoke (CS)-exposed cultures of primary human bronchial epithelial cells (pHBECs), and in CS-exposed mice. Next, we exposed GDF-15 KO and control mice to air or CS and evaluated pulmonary inflammation. GDF-15 levels were higher in sputum supernatant and lung tissue of patients with COPD and smokers without COPD compared with never smokers. Immunohistochemistry revealed GDF-15 staining in the airway epithelium. Increased expression and secretion of GDF-15 was confirmed in vitro in CS-exposed pHBECs compared with air-exposed pHBECs. Similarly, GDF-15 levels were increased in lungs of CS-exposed mice. Importantly, GDF-15 deficiency attenuated the CS-induced pulmonary inflammation. These results suggest that increased GDF-15-as observed in lungs of smokers and patients with COPD-contributes to CS-induced pulmonary inflammation.

Emerging pharmaceutical therapies for COPD

COPD, for which cigarette smoking is the major risk factor, remains a worldwide burden. Current therapies provide only limited short-term benefit and fail to halt progression. A variety of potential therapeutic targets are currently being investigated, including COPD-related proinflammatory mediators and signaling pathways. Other investigational compounds target specific aspects or complications of COPD such as mucus hypersecretion and pulmonary hypertension. Although many candidate therapies have shown no significant effects, other emerging therapies have improved lung function, pulmonary hypertension, glucocorticoid sensitivity, and/or the frequency of exacerbations. Among these are compounds that inhibit the CXCR2 receptor, mitogen-activated protein kinase/Src kinase, myristoylated alanine-rich C kinase substrate, selectins, and the endothelin receptor. Activation of certain transcription factors may also be relevant, as a large retrospective cohort study of COPD patients with diabetes found that the peroxisome proliferator-activated receptor γ (PPARγ) agonists rosiglitazone and pioglitazone were associated with reduced COPD exacerbation rate. Notably, several therapies have shown efficacy only in identifiable subgroups of COPD patients, suggesting that subgroup identification may become more important in future treatment strategies. This review summarizes the status of emerging therapeutic pharmaceuticals for COPD and highlights those that appear most promising.

Growth differentiation factor-15 is a predictor of important disease outcomes in patients with COPD

Increased levels of growth differentiation factor-15 (GDF15) are associated with cachexia, cardiovascular disease and all-cause mortality. The role of GDF15 in chronic obstructive pulmonary disease (COPD) is unknown.

The study included 413 patients with COPD from the Bergen COPD Cohort Study. All patients had a forced expiratory volume in 1 s (FEV1) <80% predicted, a FEV1 to forced vital capacity (FVC) ratio <0.7 and a history of smoking. Spirometry, fat free mass index, blood gases and plasma GDF15 were measured at baseline. Patients were followed for 3 years regarding exacerbations and changes in lung function, and 9 years for mortality. Yearly exacerbation rate, survival and yearly change in FEV1/FVC were evaluated with regression models.

Median plasma GDF15 was 0.86 ng·mL−1 (interquartile range 0.64–1.12 ng·mL−1). The distribution was not normal and GDF15 was analysed as a categorical variable. High levels of GDF15 were associated with a higher exacerbation rate (incidence rate ratio 1.39, 95% CI 1.1–1.74, p=0.006, adjusted values). Furthermore, high levels of GDF15 were associated with higher mortality (hazard ratio 2.07, 95% CI 1.4–3.1, p<0.001) and an increased decline in both FEV1 (4.29% versus 3.25%) and FVC (2.63% versus 1.44%) in comparison to low levels (p<0.01 for both).

In patients with COPD, high levels of GDF15 were independently associated with a higher yearly rate of exacerbations, higher mortality and increased decline in both FEV1 and FVC.

GDF-15 plasma levels in chronic obstructive pulmonary disease are associated with subclinical coronary artery disease

BACKGROUND

Growth differentiation factor-15 (GDF-15), a cytokine associated with cardiovascular mortality, increases during chronic obstructive pulmonary disease (COPD) exacerbations, but any role in stable COPD is unknown. We tested associations between GDF-15 and subclinical coronary atherosclerosis, assessed by coronary artery calcium (CAC) score, in COPD subjects free of clinical cardiovascular disease (CVD).

METHODS

Cross-sectional analysis of COPD participants (GOLD stages 2-4) in the COPDGene cohort without CVD at enrollment, using baseline CAC (from non-EKG-gated chest computed tomography) and plasma GDF-15 (by custom ELISA). We used multinomial logistic modeling of GDF-15 associations with CAC, adjusting for demographics, baseline risk (calculated using the HEART: Personal Heart Early Assessment Risk Tool (Budoff et al. 114:1761-1791, 2006) score), smoking history, measures of airflow obstruction, emphysema and airway disease severity.

RESULTS

Among 694 participants with COPD (47% women, mean age 63.6 years) mean GDF-15 was 1,304 pg/mL, and mean CAC score was 198. Relative to the lower GDF-15 tertile, higher tertiles showed bivariate association with increasing CAC score (mid tertile odds ratio [OR] 1.80, 95% confidence interval [CI] 1.29, 2.51; higher tertile OR 2.86, CI 2.04, 4.02). This association was maintained after additionally adjusting for baseline CVD risk, for co-morbidities and descriptors of COPD severity and impact, markers of cardiac stress (N-terminal pro-B-type natriuretic peptide, troponin T) and of inflammation (Interleukin-6), and in subgroup analysis excluding men, diabetics, current smokers or those with limited ambulation.

CONCLUSIONS

In ever-smokers with COPD free of clinical CVD, GDF-15 contributes independently to subclinical coronary atherosclerosis.

TRIAL REGISTRATION

ClinicalTrials.gov, NCT00608764 . Registered 28 January 2008.

IL-8 predicts early mortality in patients with acute hypercapnic respiratory failure treated with noninvasive positive pressure ventilation

Background

Patients with Acute Hypercapnic Respiratory Failure (AHRF) who are unresponsive to appropriate medical treatment, are often treated with Noninvasive Positive Pressure Ventilation (NPPV). Clinical predictors of the outcome of this treatment are scarce. Therefore, we evaluated the role of the biomarkers IL-8 and GDF-15 in predicting 28-day mortality in patients with AHRF who receive treatment with NPPV.

Methods

The study population were 46 patients treated with NPPV for AHRF. Clinical and background data was registered and blood samples taken for analysis of inflammatory biomarkers. IL-8 and GDF-15 were selected for analysis, and related to risk of 28-day mortality (primary endpoint) using Cox proportional hazard models adjusted for gender, age and various clinical parameters.

Results

Of the 46 patients, there were 3 subgroup in regards to primary diagnosis: Acute Exacerbation of COPD (AECOPD, n = 34), Acute Heart Failure (AHF, n = 8) and Acute Exacerbation in Obesity Hypoventilation Syndrome (AEOHS, n = 4). There was significant difference in the basic characteristic of the subgroups, but not in the clinical parameters that were used in treatment decisions. 13 patients died within 28 days of admission (28%). The Hazard Ratio for 28-days mortality per 1-SD increment of IL-8 was 3.88 (95% CI 1.86–8.06, p < 0.001). When IL-8 values were divided into tertiles, the highest tertile had a significant association with 28 days mortality, HR 10.02 (95% CI 1.24–80.77, p for trend 0.03), compared with the lowest tertile. This correlation was maintained when the largest subgroup with AECOPD was analyzed. GDF-15 was correlated in the same way, but when put into the same model as IL-8, the significance disappeared.

Conclusion

IL-8 is a target to explore further as a predictor of 28 days mortality, in patients with AHRF treated with NPPV.

Validation of the breathlessness, cough and sputum scale to predict COPD exacerbation

The breathlessness, cough and sputum scale (BCSS) is a three-item questionnaire rating breathlessness, cough and sputum on a 5-point Likert scale from 0 (no symptoms) to 4 (severe symptoms). Researchers have explored the utility of this tool to quantify efficacy of treatment following a chronic obstructive pulmonary disease (COPD) exacerbation; however, little work has been done to investigate the ability of the BCSS to predict COPD exacerbation. As part of a prospective case-crossover study among a cohort of 168 COPD patients residing in central Massachusetts, patients were asked standard BCSS questions during exacerbation and randomly identified non-exacerbation (or healthy) weeks. We found that the BCSS was strongly associated with COPD exacerbation (OR=2.80, 95% CI=2.27-3.45) and that a BCSS sum score of 5.0 identified COPD exacerbation with 83% sensitivity and 68% specificity. These results may be useful in the clinical setting to expedite interventions of exacerbation.

Use of biologics to treat acute exacerbations and manage disease in asthma, COPD and IPF

A common feature of chronic respiratory disease is the progressive decline in lung function. The decline can be indolent, or it can be accelerated by acute exacerbations, whereby the patient experiences a pronounced worsening of disease symptoms. Moreover, acute exacerbations may also be a marker of insufficient disease management. The underlying cause of an acute exacerbation can be due to insults such as pathogens or environmental pollutants, or the cause can be unknown. For each acute exacerbation, the patient may require medical intervention such as rescue medication, or in more severe cases, hospitalization and ventilation and have an increased risk of death. Biologics, such as monoclonal antibodies, are being developed for chronic respiratory diseases including asthma, COPD and IPF. This therapeutic approach is particularly well suited for chronic use based on the route and frequency of delivery and importantly, the potential for disease modification. In recent clinical trials, the frequency of acute exacerbation has often been included as an endpoint, to help determine whether the investigational agent is impacting disease. Therefore the significance of acute exacerbations in driving disease, and their potential as a marker of disease activity and progression, has recently received much attention. There is also now a need to standardize the definition of an acute exacerbation in specific disease settings, particularly as this endpoint is increasingly used in clinical trials to also assess therapeutic efficacy. Moreover, specifically targeting exacerbations may offer a new therapeutic approach for several chronic respiratory diseases.

Interleukin-16-producing NK cells and T-cells in the blood of tobacco smokers with and without COPD

Background

Long-term exposure to tobacco smoke causes local inflammation in the airways that involves not only innate immune cells, including NK cells, but also adaptive immune cells such as cytotoxic (CD8⁺) and helper (CD4⁺) T-cells. We have previously demonstrated that long-term tobacco smoking increases extracellular concentration of the CD4⁺-recruiting cytokine interleukin (IL)-16 locally in the airways. Here, we hypothesized that tobacco smoking alters IL-16 biology at the systemic level and that this effect involves oxygen free radicals (OFR).

Methods

We quantified extracellular IL-16 protein (ELISA) and intracellular IL-16 in NK cells, T-cells, B-cells, and monocytes (flow cytometry) in blood samples from long-term tobacco smokers with and without chronic obstructive pulmonary disease (COPD) and in never-smokers. NK cells from healthy blood donors were stimulated with water-soluble tobacco smoke components (cigarette smoke extract) with or without an OFR scavenger (glutathione) in vitro and followed by quantification of IL-16 protein.

Results

The extracellular concentrations of IL-16 protein in blood did not display any substantial differences between groups. Notably, intracellular IL-16 protein was detected in all types of blood leukocytes. All long-term smokers displayed a decrease in this IL-16 among NK cells, irrespective of COPD status. Further, both NK and CD4⁺ T-cell concentrations displayed a negative correlation with pack-years. Moreover, cigarette smoke extract caused release of IL-16 protein from NK cells in vitro, and this was not affected by glutathione, in contrast to the decrease in intracellular IL-16, which was prevented by this drug.

Conclusion

Long-term exposure to tobacco smoke does not markedly alter extracellular concentrations of IL-16 protein in blood. However, it does decrease the intracellular IL-16 concentrations in blood NK cells, the latter effect involving OFR. Thus, long-term tobacco smoking exerts an impact at the systemic level that involves NK cells; innate immune cells that are critical for host defense against viruses and tumors – conditions that are overrepresented among smokers.

Imbalance between subsets of CD8(+) peripheral blood T cells in patients with chronic obstructive pulmonary disease

Background. CD8⁺ T lymphocytes are known to play a critical role in the pathogenesis of chronic obstructive pulmonary disease (COPD). However, systematic analyses of CD8⁺ T cell (Cytotoxic T cells, Tc) subsets in COPD patients have yet to be well conducted.

Methods. The whole Tc subsets, including Tc1/2/10/17, CD8⁺ regulatory T cells (Tregs) and CD8⁺α7⁺ T cells, were quantified by flow cytometry in peripheral blood from 24 stable COPD subjects (SCOPD), 14 patients during acute exacerbations (AECOPD), and 14 healthy nonsmokers (HN).

Results. Acute exacerbations of COPD were accompanied by elevated levels of circulating CD8⁺ T cells. Tc1 cells were increased in both SCOPD and AECOPD patients, whereas the percentage of Tc2 cells was decreased in SCOPD patients but remained normal in AECOPD patients. Tc17 cells were increased only in AECOPD patients, and the percentage of Tc10 cells was reduced in both SCOPD and AECOPD patients. The imbalances of pro/anti-inflammatory Tc subsets observed in COPD may be caused by the lack of Tc10 cells and the impaired anti-inflammatory capacity of CD8⁺ Tregs.

Conclusions. The imbalances between subsets of CD8⁺ peripheral blood T cells contribute to the immune response dysfunction in COPD pathogenesis.

Chronic obstructive pulmonary disease comorbidities

PURPOSE OF REVIEW

Classic descriptions of chronic obstructive pulmonary disease (COPD) centered on its impact on respiratory function. It is currently recognized that comorbidities contribute to the severity of symptoms and COPD progression. Understanding COPD-comorbidities associations could provide innovative treatment strategies and identify new mechanistic pathways to be targeted.

RECENT FINDINGS

Some comorbidities are clustered with specific COPD phenotypes. There are stronger associations between airway-predominant disease and cardio-metabolic comorbidities, whereas in emphysema-predominant COPD sarcopenia and osteoporosis are frequent. These patterns suggest different inflammatory pathways acting by COPD phenotype. Osteoporosis is a major concern in COPD, particularly among men. Although β-blockers use for cardiac indications in COPD remains low, recent evidence suggests that this medication group could decrease COPD exacerbations. Gastroesophageal reflux is consistently associated with poor COPD outcomes, but mechanisms and impact of treatment are still unclear. Nontraditional comorbid conditions, such as cognitive impairment, anxiety, and depression have significant impact in COPD outcomes.

SUMMARY

Clinicians should screen their COPD patients for the presence of cardiovascular disease, diabetes, osteoporosis, sleep apnea, and sarcopenia, comorbidities for which specific treatments are available and associated with better COPD outcomes. The impact of interventions to treat gastroesophageal reflux disease, anxiety and depression is still to be defined.

Update on molecular mechanisms of corticosteroid resistance in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD) is an inflammatory and irreversible pulmonary disorder that is characterized by inflammation and airway destruction. In recent years, COPD has become a global epidemic due to increased air pollution and exposure to cigarette smoke. Current therapeutics using bronchiodialator and anti-inflammatory corticosteroids are most widely used for all patients with persistent COPD, but these approaches are disappointing due to limited improvement in symptom control and survival rate. More importantly, a certain number of COPD patients are resistant to the corticosteroid treatment and their symptoms worsen. Therefore, more effective anti-inflammatory drugs and combinational treatment are required. Understanding of the underlying molecular and immunological mechanisms is critical to developing new therapeutics. Lung inflammation and the released pro-inflammatory cytokines affect glucocorticoid receptor (GR), histone deacetylase 2 (HDAC2) and surfactant protein D (SP-D) activities in many cell types. Macrophages, neutrophils, airway epithelial cells and lymphocytes are involved in the induction of corticosteroid resistance. This review updated the recent advances in molecular and immunological mechanisms of steroid resistance among patients and animal models with COPD. Meanwhile we discussed novel therapeutic approaches in controlling lung inflammation and improving corticosteroid sensitivity among the steroid resistant patients with COPD.