Clinical significance of expression of toll-like receptor 4 on CD14+ monocytes in peripheral blood from patients with chronic obstructive pulmonary disease

Abstract

Objective To detect the effects of glucocorticoids on the expression of toll-like receptor 4 (TLR4) on CD14+ monocytes in peripheral blood from patients with chronic obstructive pulmonary disease (COPD) and explore the relationship between inherent immunity deficiency and the pathogenesis of COPD. Methods A total of 30 hospitalized acute exacerbations of COPD (AECOPD) patients from 2012 January to March were divided them into 2 groups of mild-moderate (A, n=15) and severe-critical (B, n=15) according to pulmonary functions. The same basic treatment (anti-infection, oxygen inhalation, bronchial smooth muscle relaxing and cough relief) was administered. And glucocorticoids were added to Group B. Two weeks later, AECOPD achieved a clinical remission and it was designated as a stable COPD group. Another 30 healthy cases over the same period were selected as control group. Flow cytometry was used to measure the relative mean fluorescence intensity (rmfi) and relative positive cell percent (rpcp) of TLR4 onr CD14 positive peripheral blood monocytes. Conventional pulmonary function test (FEV1 percentage of predicted value, FEV1/FVC value) was performed. Results The value of rmfi for TLR4 of AECOPD group was 5.14±0.26 and rpcp (4.24±0.17)% and they were similar to those of COPD group [4.46±0.24 and (3.49±0.24)% respectively, all P>0.05]. AECOPD and COPD groups were both significantly lower than normal control group [13.75±0.28 and (10.25±0.13)% respectively, all P<0.01]. The rmfi of TLR4 of Group B was 3.12±0.15 and rpcp (3.17±0.10)%. And both were significantly lower than those of Group A [5.48±0.23 and (5.12±0.20)% respectively, all P<0.01]. The value of rmfi for TLR4 of Group B before glucocorticoid treatment was 3.12±0.15 and rpcp (3.17±0.10)%. And both were significantly lower than those of later glucocorticoid treatment [5.24±0.25 and (5.44±0.19)% respectively, all P<0.01]. Both values were significantly lower than those of normal control group [13.75±0.28 and (10.25±0.13)% respectively, all P<0.01]. The expression of TLR4 on CD14+ monocytes in peripheral blood of AECOPD patients was positively correlated with FEV1 percentage of predicted value(r1=0.824, P<0.001) and FEV1/FVC (r2=0.756, P<0.001). Conclusions Innate immunodeficiency plays an important role in the pathogenesis of COPD. And the expression of TLR4 is an important indicator for disease severity. Glucocorticoids treat COPD through inhibiting airway inflammation response and enhancing defensive function of innate immune system. Key words: Pulmonary disease, chronic obstructive; CD14+ monocyte; Toll like receptor-4