Abstract
BACKGROUND: The link between long-term ICS therapy and respiratory infection in COPD patients is controversial. We investigated the effect of long-term use of inhaled corticosteroid on Toll like receptor 2 (TLR2) expression in induced sputum from COPD patients. METHODS: 51 patients were divided into two groups according to their treatment history: long-term ICS treatment group (patients who have used ICS (equivalent to Fluticasone Propionate (FP) ≥ 500 ug/day for more than 1 year) (n = 21) and ICS naive group (who have never routinely used ICS before, n = 29). In their induced sputum, we tested TLR2 extracellular and intracellular expression on macrophages using flowcytometry. TLR2 and tumor necrosis factor αmRNA expression were also evaluated by real-time PCR. RESULTS: TLR2 extracellular expression on the macrophages from induced sputum in long-term ICS treatment group was lower than the ICS naïve group (13.69% ± 1.17% vs 20.12% ± 4.37%, p = 0.019). TLR2 intracellular expression in the macrophages, the TLR2 and TNFαmRNA in the induced sputum also showed a trend towards decreased endpoint in ICS long-term treatment group compare to ICS naïve group but did not reach significance. TLR2 extracellular and TLR2 intracellular expression were strongly related (r = 0.645, p = P = 0.017) as well as TNFαmRNA and TLR2 mRNA expression (r = 0.894, p = 0.0001). CONCLUSION: Long-term use of ICS may have negative influence on TLR2 expression in the airway of severe COPD patient.