[Methylprednisolone enhances the expression of Toll-like receptor 2 on macrophages in induced sputum from patients with chronic cough].

OBJECTIVE: To explore the relationship between airway inflammation and Toll-like receptor 2 (TLR2) expression on macrophages in induced sputum from chronic cough patients, and to observe the effect of methylprednisolone on this receptor. METHODS: Eighty-six outpatients with chronic cough were enrolled in this study from the respiratory department in the Affiliated Hospital of Luzhou Medical College from September 2008 to March 2010. These diseases were diagnosed according to the guideline of Chinese Society of Respiratory Diseases in 2005, excluding severe liver, heart and kidney pathology and pregnant women. Among 86 cases, 31 were cough variant asthma (CVA), 14 upper airway cough syndrome (UACS), 16 eosinophilic bronchitis (EB) and 25 gastroesophageal reflux (GERC). Twenty healthy volunteers were included as controls. Induced sputum was collected and cell counts were analyzed. TLR2 expression on macrophages was determined by immunofluorescence staining. Cytokine levels were measured with enzyme linked immunosorbent assay (ELISA). RESULTS: (1) The total inflammatory cells [(3.4 ± 1.1) × 10(6)/L, (2.6 ± 0.6) × 10(6)/L, (2.6 ± 0.6) × 10(6)/L, (2.7 ± 0.5) × 10(6)/L] and neutrophils (0.52 ± 0.06, 0.58 ± 0.06, 0.52 ± 0.04, 0.54 ± 0.06) in induced sputum from CVA, UACS, EB and GERC were significantly increased (t value = 5.27, 4.09, 3.16, 3.92 and 3.62, 3.49, 4.82, 6.17 respectively, all P < 0.01), with decreased macrophages (0.35 ± 0.04, 0.40 ± 0.06, 0.38 ± 0.04, 0.43 ± 0.05) in comparison with the control group (t value = 4.76, 5.24, 4.57, 3.18, all P < 0.01). There was a significant increase in eosinophils (0.118 ± 0.054, 0.099 ± 0.034) in CVA and EB group (t value = 4.46, 3.87, 5.19 and 3.51, 4.06, 4.38 respectively, all P < 0.01). (2) The concentration of IL-8 [(7.0 ± 1.2) µg/L, (10.2 ± 3.1) µg/L, (6.3 ± 1.9) µg/L, (7.7 ± 2.5) µg/L] and TNF-α [(30 ± 11) ng/L, (46 ± 16) ng/L, (21 ± 5) ng/L, (33 ± 15) ng/L] from induced sputum in CVA, UACS, EB and GERC groups were significantly increased, compared with the control group(t value = 4.58, 3.67, 4.26, 5.39 and 5.16, 3.97, 4.59, 3.34 respectively, all P < 0.01). (3) The concentration of IL-8 was positively correlated with neutrophils in each group (R value = 0.628, 0.816, 0.769 and 0.733 respectively, all P < 0.05). The concentration of TNF-α was also positively correlated with neutrophils in each group (R value = 0.579, 0.865, 0.730 and 0.755 respectively, all P < 0.05). (4) The expression of TLR2 (56 ± 15, 38 ± 7, 65 ± 17, 27 ± 4) on macrophages in CVA, UACS, EB and GERC was significantly decreased. The expression of TLR2 (75 ± 17, 53 ± 16, 94 ± 30, 41 ± 5) on macrophages was enhanced by methylprednisolone. CONCLUSIONS: The expression of TLR2 on macrophages from induced sputum in CVA, UACS, EB and GERC was decreased, but could be enhanced by methylprednisolone, suggesting that TLR2 might play a regulatory role in airway inflammatory response.