Implications of the inflammatory response for the identification of biomarkers of chronic obstructive pulmonary disease

COPD: systemic proteomic profiles in frequent and infrequent exacerbators

Background

Some patients with COPD suffer frequent exacerbations (FE). We hypothesised that their systemic proteomic profile would be different from that of non-frequent exacerbators (NFE). The objective of the present study was to contrast the systemic proteomic profile in FE versus NFE. As a reference, we also determined the systemic proteomic profile of healthy controls (HC) and COPD patients during an actual episode of exacerbation (AE).

Methods

In the analysis we included 40 clinically stable COPD patients (20 FE and 20 NFE), and 20 HC and 10 AE patients. Their plasma samples were analysed by combining two complementary proteomic approaches: label-free liquid chromatography-tandem mass spectrometry and multiplex immunoassays. Gene Ontology annotation, pathway enrichment and network analyses were used to investigate molecular pathways associated with differentially abundant proteins/peptides (DAPs).

Results

Compared with HC, we identified 40 DAPs in FE, 10 in NFE and 63 in AE. Also compared to HC, pathway functional and protein-protein network analyses revealed dysregulation of inflammatory responses involving innate and antibody-mediated immunity in COPD, particularly in the FE group, as well as during an AE episode. Besides, we only identified alterations in the complement and coagulation cascades in AE.

Conclusion

There are specific plasma proteome profiles associated with FE, which are partially shared with findings observed during AE, albeit others are uniquely present during the actual episode of AE.

The association between sarcopenia and incident chronic lung disease in the general population: A longitudinal study based on CHARLS data

BACKGROUND

Data regarding the association of sarcopenia with chronic lung disease (CLD) has led to inconclusive results. The main goal of this research was to investigate the association between sarcopenia and CLD in middle-aged and elderly individuals in China.

METHODS

The study sample consisted of 11,077 individuals without CLD at baseline chosen from the China Health and Retirement Longitudinal Study (CHARLS) data from 2015, followed up until 2018. Sarcopenia was identified utilizing the criteria set by the Asian Working Group on Sarcopenia (AWGS 2019) in 2019. Individuals were categorized into no-sarcopenia, possible-sarcopenia, and sarcopenia groups. The outcome of the study was considered to be incident CLD, which included chronic bronchitis, emphysema, pulmonary heart disease, and asthma. The association between sarcopenia and the risk of CLD was also examined by employing weighted Cox proportional hazard regression models.

RESULTS

A total of 356 (3.20 %) participants developed CLD during the 3.6-year follow-up period. The cumulative incidence of CLD in the no-sarcopenia, possible-sarcopenia, and sarcopenia groups was 2.80 % (230/8222), 4.37 % (55/1260), and 4.45 % (71/1595), respectively. Individuals with possible sarcopenia {hazard ratio [HR] [95 % confidence interval (CI)]: 1.48 [1.04-2.09]} and sarcopenia [HR (95 % CI): 1.68 (1.12-2.51)] demonstrated a considerably high risk of developing CLD compared to individuals in the no-sarcopenia group. Moreover, individuals diagnosed with sarcopenia, as per the criteria established by the European Working Group on Sarcopenia in Older People (EWGSOP) 2018, were at considerably high risk for developing CLD compared to those in the no-sarcopenia group.

CONCLUSION

This research involving adult Chinese individuals demonstrated a significant association between, possible sarcopenia and sarcopenia with an elevated risk of incident CLD, thereby emphasizing the importance of monitoring respiratory health in this population.

KEY POINTS

Question: Whether muscle mass and sarcopenia are associated with the development of chronic lung disease (CLD) in Asian middle-aged and elderly individuals.

FINDINGS

This longitudinal study encompassing 11,077 adults aged ≥45 years from the China Health and Retirement Longitudinal Study (CHARLS) data with 3.6 years of follow-up revealed a positive association between sarcopenia at baseline and incidence of CLD. Meaning: The findings suggest that possible sarcopenia and sarcopenia are linked to the development of CLD. Consequently, middle-aged and elderly individuals with possible sarcopenia and sarcopenia can be considered vulnerable regarding the primary prevention strategies for CLD.

The effect of two-month treatment with Zataria multiflora on inflammatory cytokines, pulmonary function testes and respiratory symptoms in patients with chronic obstructive pulmonary disease (COPD)

ETHNOPHARMACOLOGICAL RELEVANCE

Zataria multiflora Boiss. (Z. multiflora) is a valuable medicinal plant that has been used in Iranian traditional and folk medicine as an antiseptic, carminative, diaphoretic, diuretic, anti-spasmodic and analgesic herbal medicine. This plant has been also used to relieve cough in common cold and respiratory tract disorders. The previous studies reported the pharmacological effects of Z. multiflora such as anti-inflammatory and anti-oxidant properties in respiratory disorders in animal models and clinical studies.

AIM OF THE STUDY

The effects of Z. multiflora extract on inflammatory cytokines, pulmonary function tests (PFT), and respiratory symptoms in chronic obstructive pulmonary diseases (COPD) patients were investigated.

MATERIALS AND METHODS

COPD patients (41 cases) were divided to three groups including placebo group (P) and groups received 3 and 6 mg/kg/day Z. multiflora extract (Z3 and Z6) for two months. Inflammatory cytokines, PFT values, and respiratory symptoms were assessed before treatment (stage 0), one (stage I) and two (stage II) months after treatment.

RESULTS

Serum levels of TNF-α and IL-8 were significantly decreased after two months treatment compared to baseline values in Z3 and Z6 groups. The PFT values including forced vital capacity (FVC) and forced expiratory volume in 1 s (FEV1) were significantly increased during two months treatment with Z3 and Z6. The peak expiratory flow (PEF) was also significantly increased after one-month treatment with Z6. The respiratory symptoms including cough, chest tightness, modified medical research council (mMRC) dyspnea scale were significantly improved after one and two treatments with both doses of Z. multiflora compared to baseline values.

CONCLUSION

The results suggest the potential therapeutic effect of Z. multiflora in COPD patients through reduction of inflammatory cytokines, increasing PFT values and improvement of respiratory symptoms.

VEGF Receptor 1 Promotes Hypoxia-Induced Hematopoietic Progenitor Proliferation and Differentiation

Although it is well known that hypoxia incites unleashed cellular inflammation, the mechanisms of exaggerated cellular inflammation in hypoxic conditions are not known. We observed augmented proliferation of hematopoietic stem and progenitor cells (HSPC), precursors of inflammatory leukocytes, in mice under hypoxia. Consistently, a transcriptomic analysis of human HSPC exposed to hypoxic conditions revealed elevated expression of genes involved in progenitor proliferation and differentiation. Additionally, bone marrow cells in mice expressed high amount of vascular endothelial growth factor (VEGF), and HSPC elevated VEGF receptor 1 (VEGFr1) and its target genes in hypoxic conditions. In line with this, VEGFr1 blockade in vivo and in vitro decreased HSPC proliferation and attenuated inflammation. In silico and ChIP experiments demonstrated that HIF-1α binds to the promoter region of VEGFR1. Correspondingly, HIF1a silencing decreased VEGFr1 expression in HSPC and diminished their proliferation. These results indicate that VEGF signaling in HSPC is an important mediator of their proliferation and differentiation in hypoxia-induced inflammation and represents a potential therapeutic target to prevent aberrant inflammation in hypoxia-associated diseases.

A Novel Processing-Free Method for RNAseq Analysis of Spontaneous Sputum in Chronic Obstructive Pulmonary Disease

Background: Assessments of airways inflammation in patients with chronic obstructive pulmonary disease (COPD) require semi-invasive procedures and specialized sample processing know-how. In this study we aimed to set up and validate a novel non-invasive processing-free method for RNA sequencing (RNAseq) of spontaneous sputum samples collected from COPD patients.

Methods: Spontaneous sputum samples were collected and stabilized, with or without selection of plugs and with or without the use of a stabilizer specifically formulated for downstream diagnostic testing (PrimeStore® Molecular Transport Medium). After 8 days storage at ambient temperature RNA was isolated according to an optimized RNAzol® method. An average percentage of fragments longer than 200 nucleotides (DV₂₀₀) >30% and an individual yield >50 ng were required for progression of samples to sequencing. Finally, to assess if the transcriptome generated would reflect a true endotype of COPD inflammation, the outcome of single-sample gene-set enrichment analysis (ssGSEA) was validated using an independent set of processed induced sputum samples. Results: RNA extracted from spontaneous sputum using a stabilizer showed an average DV₂₀₀ higher than 30%. 70% of the samples had a yield >50 ng and were submitted to downstream analysis. There was a straightforward correlation in terms of gene expression between samples handled with or without separation of plugs. This was also confirmed by principal component analysis and ssGSEA. The top ten enriched pathways resulting from spontaneous sputum ssGSEA were associated to features of COPD, namely, inflammation, immune responses and oxidative stress; up to 70% of these were in common within the top ten enriched pathways resulting from induced sputum ssGSEA.

Conclusion: This analysis confirmed that the typical COPD endotype was represented within spontaneous sputum and supported the current method as a non-invasive processing-free procedure to assess the level of sputum cell inflammation in COPD patients by RNAseq analysis.

Expression and clinical significance of serum amyloid A and interleukin-6 in patients with acute exacerbation of chronic obstructive pulmonary disease

Expression and clinical significance of serum amyloid A (SAA) and interleukin-6 (IL-6) in patients with acute exacerbation of chronic obstructive pulmonary disease (AECOPD) were investigated. Fifty-one patients with AECOPD (acute group, AG) and 51 patients with stable chronic obstructive pulmonary disease (stable group, SG) admitted to Qingdao Eighth People's Hospital were selected. The expression levels of SAA and IL-6 in peripheral blood of patients in the two groups were detected and compared before and after treatment. Pearson analysis was used in the correlation between SAA and IL-6 and Receiver operating characteristic (ROC) curve was employd to analyze the predictive value of SAA and IL-6 for AECOPD progression. Logistic regression analysis was used to analyze the risk factors of AECOPD patients. The expression levels of SAA and IL-6 of patients in AG were significantly higher than those in SG (P<0.05). Pearson analysis showed that SAA was positively correlated with IL-6 expression (P<0.05). ROC curve analysis showed that AUC predicted by SAA and IL-6 for AECOPD progress was 0.789 and 0.762 (P<0.05). Logistic regression analysis showed that SAA and IL-6 were prediction indexes of AECOPD progression. The levels of SAA and IL-6 were significantly increased during AECOPD and effectively predicted the progress of AECOPD and is a risk factor affecting AECOPD patients.

Assessment of serum levels of DIO1 and DIO3 in patients diagnosed with COPD

PURPOSE

Chronic obstructive pulmonary disease is the most common chronic lung disease, which may be caused by different pathological processes, including inflammation. Furthermore, signs of changes in thyroid hormone levels are found in some patients. Deiodinases (DIOs) are selenoproteins (enzymes) involved in the synthesis of thyroid hormones. It has been found that these molecules are involved in inflammatory processes. We carried out this preliminary study to investigate the levels of two deiodinases, i.e. type 1 deiodinase (DIO1) and type 3 deiodinase (DIO3), and their possible association with COPD and specific clinical parameters.

PATIENTS AND METHODS

Serum levels of DIO1 and DIO3 as well as lung function parameters were measured in 50 patients suffering from COPD and 30 healthy control subjects. The Mann-Whitney U test and Pearson's correlation coefficient were used to compare and correlate data.

RESULTS

Serum levels of DIO1 and DIO3 were significantly elevated in COPD patients (97.9 ± 55.6 versus 28.2 ± 28.3 U/L for DIO1 and 19.6 ± 10.7 versus 6.4 ± 6.3 U/L for DIO3; p < 0.001). No correlation between serum levels of the examined DIOs and other sociodemographic and clinical parameters was identified in this study.

CONCLUSION

For the first time we observed that peripheral DIO1 and DIO3 concentrations were elevated in COPD; hence, we may cautiously begin considering these molecules as potential circulating biomarkers of COPD. It may also be beneficial to conduct further studies to confirm and clarify their potential role.

Tumor necrosis factor receptor 2 as a possible marker of COPD in smokers and ex-smokers

Introduction

Oxidative stress and systemic inflammation are higher in smokers and patients with COPD; however, markers that may help differentiate between smokers and patients with COPD have not yet been identified. We hypothesized that tumor necrosis factor-alpha receptor (TNFR) and soluble form of the receptor for advanced glycation end products (sRAGE) can be indicators of COPD in asymptomatic patients.

Patients and methods

We evaluated 32 smokers (smoking history >10 pack-years), 32 patients with mild/moderate COPD (smokers and ex-smokers), and 32 never smokers. Concentrations of C-reactive protein (CRP), interleukin (IL)-6, TNFR1 and TNFR2, advanced glycation end products (AGEs), and the sRAGE were measured in serum.

Results

There were higher CRP and AGEs concentrations in smokers and in patients with COPD (P<0.001 and P=0.01, respectively) compared to controls, without statistical difference between smokers and patients with COPD. Concentrations of sRAGE, IL-6, and TNFR1 did not differ between study groups. TNFR2 was significantly higher in patients with COPD than in smokers (P=0.004) and controls (P=0.004), and the presence of COPD (P=0.02) and CRP (P=0.001) showed a positive association with TNFR2. Positive associations for smoking (P=0.04), CRP (P=0.03), and IL-6 (P=0.03) with AGEs were also found. The interaction variable (smoking × COPD) showed a positive association with IL-6.

Conclusion

Our data suggest that TNFR2 may be a possible marker of COPD in asymptomatic smokers and ex-smokers. Although smokers and patients with early COPD presented other increased systemic inflammation markers (eg, CRP) and oxidative stress (measured by AGEs), they did not differentiate smokers from COPD.