High Serum Fractalkine/CX3CL1 in Patients with Chronic Obstructive Pulmonary Disease: Relationship with Emphysema Severity and Frequent Exacerbation

New markers in chronic obstructive pulmonary disease

Chronic obstructive pulmonary disease (COPD), a global healthcare and socioeconomic burden, is a multifaceted respiratory disorder that results in substantial decline in health status and life quality. Acute exacerbations of the disease contribute significantly to increased morbidity and mortality. Consequently, the identification of reliable and effective biomarkers for rapid diagnosis, prediction, and prognosis of exacerbations is imperative. In addition, biomarkers play a crucial role in monitoring responses to therapeutic interventions and exploring innovative treatment strategies. Although established markers such as CRP, fibrinogen and neutrophil count are routinely used, a universal marker is lacking. Fortunately, an increasing number of studies based on next generation analytics have explored potential biomarkers in COPD. Here we review those advances and the need for standardized validation studies in the appropriate clinical setting.

Increased inflammatory mediators levels are associated with clinical outcomes and prolonged illness in severe COVID-19 patients

OBJECTIVE

The purpose of this study was to identify potential predictors of clinical outcome in severe COVID-19 patients and to investigate the relationship between immunological parameters and duration of illness.

METHODS

This single-center study retrospectively recruited 73 patients with severe or critical COVID-19. Immunological indicators include white blood cell count, neutrophil count, lymphocyte count, neutrophil-to-lymphocyte ratio, and circulating inflammatory mediators were observed for their association with disease severity, mortality and duration of illness of COVID-19.

RESULTS

Serum inflammatory mediators levels of C-reactive protein (P = 0.015), interleukin 6 (IL-6) (P < 0.001), CX3CL1 (P < 0.001), D-dimer (P < 0.001) and procalcitonin (PCT) (P < 0.001) were increased in critical illness patients compared to those severe COVID-19 patients. CX3CL1 has the highest C-index (0.75) to predict in-hospital mortality in patients with COVID-19. Furthermore, this study shows for the first time that the duration of illness in severe COVID-19 patients is associated with serum levels of CX3CL1 (P = 0.037) and D-dimer (P = 0.014).

CONCLUSION

CX3CL1, D-dimer, PCT, and IL-6 could effectively predict mortality in severe COVID-19 patients. In addition, only the circulating levels of CX3CL1 and D-dimer were significantly associated with duration of illness.

Suppression of CX3CL1 by miR-497-5p inhibits cell growth and invasion through inactivating the ERK/AKT pathway in NSCLC cells

Non-small cell lung cancer (NSCLC) is the most common lung cancer with a highest mortality rate. MiR-497-5p has been reported as tumor suppressor in many cancers, but the role and mechanism of miR-497-5p in regulating NSCLC progression are still largely unknown in vitro and in vivo. Here, miR-497-5p was significantly downregulated in human NSCLC tissues and cell lines, compared with matched adjacent tissues and normal lung epithelial cell line. Then, miR-497-5p mimic and inhibitor were, respectively, transfected into human NSCLC cells A549 and H460, CCK-8 assay, transwell assay, and flow cytometry were used to detect the capacities of cell proliferation, invasion and apoptosis. MiR-497-5p negatively regulated proliferation and invasion of NSCLC cancer cells. MiR-497-5p was demonstrated to directly bound to 3'-UTR of CX3CL1 mRNA and post-transcriptionally suppressed its expression thus inactivating its downstream oncogenic pathway ERK/AKT. Moreover, transfection with short hairpin RNA (shRNA) against CX3CL1 decreased capacity of cell proliferation and invasion and promoted cell apoptosis in NSCLC cells. In addition, ERK inhibitor U0126 attenuated the promotion effect of miR-497-5p inhibitor on activation of ERK/AKT and cell proliferation and migration. Finally, overexpression of miR-497-5p substantially suppressed activation of the ERK/AKT pathway and tumor growth in tumor-bearing mice in vivo. Taken together, our findings showed that miR-497-5p is downregulated in human NSCLC tissues and cell lines, and it inhibited tumor growth and cell invasion by targeting CX3CL1 gene to inactivate the ERK/AKT pathway in NSCLC cells.

The Relationship Between Chemokine and Chemokine Receptor Genes Polymorphisms and Chronic Obstructive Pulmonary Disease Susceptibility in Tatar Population from Russia: A Case Control Study

Chronic obstructive pulmonary disease (COPD) is a chronic inflammatory lung disease affecting primarily distal respiratory pathways and lung parenchyma. This study aimed to determine possible genetic association of chemokine and chemokine receptor genes polymorphisms with COPD in a Tatar population from Russia. SNPs of CCL20, CCR6, CXCL8, CXCR1, CXCR2, CCL8, CCL23, CCR2, and CX3CL1 genes and their gene-gene interactions were analyzed for association with COPD in cohort of 601 patients and 617 controls. As a result statistically significant associations with COPD in the study group under the biologically plausible assumption of additive genetic model were identified in CCL20 (rs6749704) (P = 0.00001, OR 1.55), CCR6 (rs3093024) (P = 0.0003, OR 0.74), CCL8 (rs3138035) (P = 0.0001, OR 0.67), CX3CL1 (rs170364) (P = 0.023, OR 1.21), CXCL8 (rs4073) (P = 0.007, OR 1.23), CXCR2 (rs2230054) (P = 0.0002, OR 1.32). Following SNPs CCL20 (rs6749704), CX3CL1 (rs170364), CCL8 (rs3138035), CXCL8 (rs4073), CXCR2 (rs2230054) showed statistically significant association with COPD only in smokers. The association of CCR6 (rs3093024) with COPD was confirmed both in smokers and in non-smokers. A relationship between smoking index and CCL20 (rs6749704) (P = 0.04), CCR6 (rs3093024) (P = 0.007), CCL8 (rs3138035) (P = 0.0043), and CX3CL1 (rs170364) (P = 0.04) was revealed. A significant genotype-dependent variation of Forced Vital Capacity was observed for CCL23 (rs854655) (P = 0.04). Forced Expiratory Volume in 1 s / Forced Vital Capacity ratio was affected by CCL23 (rs854655) (P = 0.05) and CXCR2 (rs1126579) (P = 0.02). Using the APSampler algorithm, we obtained nine gene-gene combinations that remained significantly associated with COPD; loci CCR2 (rs1799864) and CCL8 (rs3138035) were involved in the largest number of the combinations. Our results indicate that CCL20 (rs6749704), CCR6 (rs3093024), CCR2 (rs1799864), CCL8 (rs3138035), CXCL8 (rs4073), CXCR1 (rs2234671), CXCR2 (rs2230054), and CX3CL1 (rs170364) polymorphisms are strongly associated with COPD in Tatar population from Russia, alone and in combinations. For the first time combination of the corresponding SNPs were considered and as a result 8 SNP patterns were associated with increased risk of COPD.

Increased chemokines levels in patients with chronic obstructive pulmonary disease: correlation with quantitative computed tomography metrics

OBJECTIVE

We sought to explore the relationships between multiple chemokines with spirometry, inflammatory mediators and CT findings of emphysema, small airways disease and bronchial wall thickness.

METHODS

All patients with COPD (n = 65) and healthy control subjects (n = 23) underwent high-resolution CT, with image analysis determining the low attenuation area (LAA), ratio of mean lung attenuation on expiratory and inspiratory scans (E/I MLD) and bronchial wall thickness of inner perimeter of a 10-mm diameter airway (Pi10). At enrollment, subjects underwent pulmonary function studies, chemokines and inflammatory mediators measurements.

RESULTS

Multiple chemokines (CCL2, CCL3, CCL5, CX3CL1, CXCL8, CXCL9, CXCL10, CXCL11 and CXCL12) and inflammatory mediators (MMP-9, MMP-12, IL-18 and neutrophil count) were markedly increased in the serum of COPD patients compared with healthy controls. There were associations between small airway disease (E/I MLD) and CCL11, CXCL8, CXCL10, CXCL11, CXCL12 and CX3CL1. Especially CXCL8 and CX3CL1 are strongly associated with E/I MLD (r = 0.74, p < 0.001; r = 0.76, p < 0.001, respectively). CXCL8, CXCL12 and CX3CL1 were moderately positively correlated with emphysema (%LAA) (r = 0.49, p < 0.05; r = 0.51, p < 0.05; r = 0.54, p < 0.01, respectively). Bronchial wall thickness (Pi10）showed no significant differences between the COPD and healthy controls,，but there was an association between Pi10 and FEV₁% in COPD patients (r=-0.420, p = 0.048). Our statistical results showed that there were not any associations between airway wall thickness (Pi10) and chemokines.

CONCLUSION

Pulmonary chemokines levels are closely associated with the extent of gas trapping, small airways disease and emphysema identified on high-resolution chest CT scan.

ADVANCES IN KNOWLEDGE

This study combines quantitative CT analysis with multiplex chemokines and inflammatory mediators to identify a new role of pathological changes in COPD.

Role of Fractalkine in promoting inflammation in sepsis-induced multiple organ dysfunction

OBJECTIVE

Fractalkine, CX3CL1, is involved in the directional movement of chemokine cells, immune response, inflammatory response, tissue repair, and other processes. However, its role in sepsis is not well known.

METHODS

We measured circulating Fractalkine in adult patients with sepsis. Effects of Fractalkine on the survival, inflammation, tissue injury, and bacterial clearance were assessed using the WT or CX3CL^-/- murine model of cecal ligation and puncture (CLP)-induced sepsis.

RESULTS

Serum Fractalkine concentrations were significantly elevated in adult patients with sepsis compared to healthy adults. Increased Fractalkine correlated positively with the number of blood leukocytes and the level of inflammatory cytokines, including IL-6, IL-1β, IL-17A, IFN-γ, and TNF-α, and correlated negatively with IL-10 in clinical sepsis. Recombinant Fractalkine impaired survival whereas Fractalkine gene knockout or anti-Fractalkine antibody improved survival in the murine model of CLP-induced sepsis. Fractalkine administration increased inflammatory response, evident by higher levels of cytokines (TNF-α, IL-1β, IL-17A, IFN-γ, and IL-6 but not IL-10), and tissue damage (lung, liver, and kidney) in CLP-induced sepsis. Fractalkine reduced bacterial clearance in CLP-induced polymicrobial sepsis by reducing macrophage or neutrophil phagocytosis and intracellular elimination of E. coli.

CONCLUSIONS

Fractalkine aggravates sepsis by increasing inflammation and decreasing bacterial clearance, and is a potential tool for anti-sepsis therapy.

Increased levels of inflammatory biomarker CX3CL1 in patients with chronic obstructive pulmonary disease

OBJECTIVE

To investigate the concentration of CX3CL1 in serum of patients with chronic obstructive pulmonary disease (COPD), and to evaluate the associations between the CX3CL1 level and systemic inflammation, small airway obstruction, and COPD assessment test (CAT) scores in COPD patients.

METHODS

Enzyme-linked immunosorbent assay were utilized to detect the CX3CL1 protein in serum separately from 64 patients with COPD and 53 healthy controls.

RESULTS

Compared with healthy non-smokers, healthy smokers and COPD non-smokers, serum CX3CL1 protein levels were significantly elevated in COPD smokers (258.33 ± 56.27 pg/mL versus 177.32 ± 43.21 pg/mL, 185.64 ± 47.03 pg/mL, and 226.55 ± 51.79 pg/mL, P < 0.05). Correlation analysis indicated that serum CX3CL1 in COPD smokers was negatively correlated with FEV₁/FVC (justified r = -0.319, P < 0.001), FEV₁/Pre (justified r = -0.476, P < 0.001), FEV₃/FVC (justified r = -0.354, P < 0.001), MMEF25-75/Pre (justified r = -0.428, P < 0.001), but positively correlated with CRP (justified r = 0.331, P < 0.001) and MMP-12 (justified r = 0.352, P < 0.001). However, our results showed no significant correlation between serum CX3CL1 of COPD smokers and the diffusing capacity of the lung for carbon monoxide (DLCO) (justified r = 0.0397, P = 0.6025), but a positive correlation with COPD assessment test (CAT) scores (justified r = 0.367, P < 0.001). Finally, through multivariate linear analysis, statistical results demonstrated age (β = -0.2694, P = 0.005), FEV₁/Pred (β = -0.2653, P = 0.003), CRP (β = 0.1427, P = 0.0478) and MMP-12 (β = 0.430, P < 0.001) are independent parameters associated with CX3CL1.

CONCLUSION

The results demonstrated that elevated circulating CX3CL1 level is associated with the systemic inflammation, small airway obstruction, and CAT scores in COPD patients, suggesting that CX3CL1 may play crucial roles in the pathogenesis of COPD. Blocking CX3CL1 might prevent the progression of chronic obstructive pulmonary disease.

Severity of chronic obstructive pulmonary disease with 'exacerbator with emphysema phenotype' is associated with potential biomarkers

OBJECTIVE

The present study was designed to investigate the biomarkers levels of fractalkine (FKN), neutrophil elastase (NE) and matrix metalloproteinase-12 (MMP-12) in chronic obstructive pulmonary disease (COPD) with 'exacerbator with emphysema phenotype' and to evaluate the associations between the biomarkers levels and the severity of disease by spirometric measurements.

METHODS

A total of 84 COPD patients and 49 healthy controls were enrolled in our study. ELISA were utilised to detect the FKN, MMP-12 and NE in serum from all subjects.

RESULTS

FKN (p<0.001), NE (p=0.039) and MMP-12 (p<0.001) in serum of COPD patients showed higher levels than that of healthy control subjects. Serum FKN (p<0.001), MMP-12 (p<0.001) and NE (p=0.043) levels were significantly higher in severe and very severe COPD patients than that in mild and moderate COPD patients. Circulating FKN, MMP-12 and NE expression levels were significantly elevated (p<0.001) in COPD smokers compared with COPD non-smokers. The smoke pack years were negatively correlated with FEV₁%pred (r=-0.5036), FEV₁/FVC ratio (r=-0.2847) (FEV, forced expiratory volume; FVC, forced vital capacity). Similarly, we observed a strong positive correlation between the smoke pack years and serum levels of FKN (r=0.4971), MMP-12 (r=0.4315) and NE (r=0.2754). FEV₁%pred was strongly negatively correlated with cytokine levels of FKN (r=-0.4367), MMP-12 (r=-0.3295) and NE (r=-0.2684). Likewise, FEV₁/FVC ratio was negatively correlated with mediators of inflammation levels of FKN (r=-0.3867), MMP-12 (r=-0.2941) and NE (r=-0.2153).

CONCLUSION

Serum FKN, MMP-12 and NE concentrations in COPD patients are directly associated with the severity of COPD with 'exacerbator with emphysema phenotype'. This finding suggests that FKN, MMP-12 and NE might play an important role in the pathophysiology of COPD.

Chemokines in COPD: From Implication to Therapeutic Use

: Chronic Obstructive Pulmonary Disease (COPD) represents the 3rd leading cause of death in the world. The underlying pathophysiological mechanisms have been the focus of extensive research in the past. The lung has a complex architecture, where structural cells interact continuously with immune cells that infiltrate into the pulmonary tissue. Both types of cells express chemokines and chemokine receptors, making them sensitive to modifications of concentration gradients. Cigarette smoke exposure and recurrent exacerbations, directly and indirectly, impact the expression of chemokines and chemokine receptors. Here, we provide an overview of the evidence regarding chemokines involvement in COPD, and we hypothesize that a dysregulation of this tightly regulated system is critical in COPD evolution, both at a stable state and during exacerbations. Targeting chemokines and chemokine receptors could be highly attractive as a mean to control both chronic inflammation and bronchial remodeling. We present a special focus on the CXCL8-CXCR1/2, CXCL9/10/11-CXCR3, CCL2-CCR2, and CXCL12-CXCR4 axes that seem particularly involved in the disease pathophysiology.

Expressions of MMP-12, TIMP-4, and Neutrophil Elastase in PBMCs and Exhaled Breath Condensate in Patients with COPD and Their Relationships with Disease Severity and Acute Exacerbations

OBJECTIVE

The purpose of this study was to compare matrix metalloproteinase-12 (MMP-12), neutrophil elastase (NE), and tissue inhibitor of metalloproteinase-4 (TIMP-4) in peripheral blood of patients with chronic obstructive pulmonary disease (COPD) and controls. At the same time, MMP-12, NE, and TIMP-4 in exhaled breath condensate (EBC) were also evaluated.

METHODS

Peripheral blood and EBC samples from COPD patients and healthy controls were collected. In serum and EBC, MMP-12, NE, and TIMP-4 proteins were detected by enzyme-linked immunoassays. The mRNA expression levels of MMP-12, NE, and TIMP-4 in peripheral blood mononuclear cells (PBMCs) were analyzed by quantitative real-time polymerase chain reaction (qRT-PCR).

RESULTS

The concentration of TIMP-4 protein in EBC was lower in patients with COPD (P < 0.001). MMP-12 (P = 0.046), NE (P = 0.027), and TIMP-4 (P = 0.005) proteins in serum of patients with COPD showed higher levels of concentration. The mRNA of MMP-12 (P = 0.0067), NE (P = 0.0058), and TIMP-4 (P = 0.0006) in PBMCs of COPD patients showed higher expression levels. Compared with stable patients, mRNA expression level of NE (P = 0.033) in PBMCs of patients with acute exacerbation of COPD was increased. There were differences in the ratio of MMP-12/TIMP-4 in PBMC (P = 0.0055), serum (P = 0.0427), and EBC (P = 0.0035) samples between COPD patients and healthy controls. The mRNA expression of MMP-12 (r = -0.3958, P = 0.0186) and NE (r = -0.3694, P = 0.0290) in COPD patients was negatively correlated with pulmonary function. However, the mRNA expression of TIMP-4 (r = 0.2871, P = 0.0945) in PBMCs was not correlated with the FEV1 of the pulmonary function. Serum MMP-12 level was positively correlated with the MMP-12 level in EBC (P = 0.0387). The level of TIMP-4 in serum was not correlated with the level in the EBC sample (P = 0.4332).

CONCLUSION

The expression levels of MMP-12, NE, and TIMP-4 in PBMCs and serum were elevated in COPD patients. In PBMCs of COPD patients, the mRNA expression level of NE may predict acute exacerbation, and MMP-12 mRNA expression level may be used to reflect the severity of airflow limitation. However, to better assess their diagnostic or prognostic value, larger studies are necessary.