Correlation of sputum inflammatory markers with severity and blood inflammatory markers in bronchiectasis

Abstract

Background: As a disease characterized by chronic neutrophilic inflammation, various sputum biomarkers have been investigated in the association with the severity and prognosis of bronchiectasis. However, there is lack of data on the association between sputum interleukin-1beta (IL-1β), interleukin-8 (IL-8) and tumor necrosis factor-alpha (TNF-α) levels at clinical stable state and the clinical, spirometric and blood inflammatory parameters, as well as prognostic scores. The purpose of the study is to assess the association between sputum IL-1β, IL-8 and TNF-α levels at clinical stable state and various clinical and laboratory parameters in bronchiectasis.

Methods: A prospective study was conducted in a major regional hospital and tertiary respiratory referral centre in Hong Kong, including 44 Chinese patients with bronchiectasis. The correlation between stable state sputum IL-1β, IL-8 and TNF-α levels with various clinical, laboratory and spirometric parameters in bronchiectasis, as well as FACED [forced expiratory volume in one second (FEV₁), age, chronic colonisation by Pseudomonas aeruginosa, radiological extension and dyspnoea]/E-FACED (FACED plus exacerbations) scores were assessed.

Results: Baseline sputum IL-1β level was found to have significant moderate positive correlation with baseline blood high sensitivity C-reactive protein (hs-CRP) level with Pearson correlation coefficient (r) of 0.529 (P=0.001). Baseline sputum IL-8 level was found to have significant moderate positive correlation with baseline FACED and E-FACED score with r of 0.574 (P<0.001) and 0.539 (P<0.001) respectively. Baseline sputum TNF-α level was found to have significant moderate positive correlation with baseline FACED score with r of 0.520 (P<0.001).

Conclusions: Sputum IL-1β and, IL-8 and TNF-α levels were shown to have significant correlation with various clinical, laboratory and spirometry parameters in bronchiectasis, as well as more severe disease as measured by FACED and E-FACED scores.

Keywords: Bronchiectasis; interleukin-1beta (IL-1β); interleukin-8 (IL-8); sputum cytokines; tumor necrosis factor-alpha (TNF-α).

Figure 1

Scatter plots of the correlation between sputum IL-1β level and (A) baseline blood hs-CRP level, (B) baseline blood neutrophil count, (C) baseline blood lymphocyte count, (D) baseline NLR. IL-1β, interleukin-1beta; hs-CRP, high sensitivity C-reactive protein; NLR, neutrophil to lymphocyte ratio.

Figure 2

Scatter plots of the correlation between sputum IL-1β level and (A) baseline FACED score, (B) baseline E-FACED score, (C) baseline FEV₁ in litre, (D) baseline FEV₁ percentage predicted. IL-1β, interleukin-1beta; FACED, FEV₁, age, chronic colonisation by Pseudomonas aeruginosa, radiological extension and dyspnoea; E-FACED, FACED plus exacerbations; FEV₁, forced expiratory volume in one second.

Figure 3

Scatter plots of the correlation between sputum IL-8 and (A) FACED score, (B) E-FACED score, (C) baseline FEV₁ in percentage. IL-8, interleukin-8; FACED, FEV₁, age, chronic colonisation by Pseudomonas aeruginosa, radiological extension and dyspnoea; E-FACED, FACED plus exacerbations; FEV₁, forced expiratory volume in one second.

Figure 4

Scatter plots of the correlation between sputum TNF-α level and (A) baseline FACED score, (B) baseline E-FACED score, (C) baseline FEV₁ percentage predicted. TNF-α, tumor necrosis factor-alpha; FACED, FEV₁, age, chronic colonisation by Pseudomonas aeruginosa, radiological extension and dyspnoea; E-FACED, FACED plus exacerbations; FEV₁, forced expiratory volume in one second.