Thrombomodulin in exercise-induced asthma

The role of endothelium-derived mediators in exercise-induced bronchoconstriction

BACKGROUND

Exercise-induced bronchoconstriction (EIB) is a highly prevalent condition whose pathogenesis and effect on airways remain unclear. The aim of the study was to evaluate the changes in endothelial-derived mediators following intensive exercise in asthmatic patients.

METHODS

The study was conducted in a group of 25 asthmatic patients (15 with EIB, 10 without EIB) and 8 healthy volunteers. Changes induced by intensive exercise in the plasma concentrations of endothelin-1 (ET-1), thrombomodulin and soluble E-selectin were determined. Moreover, the possible correlations of these measurements with the results of baseline lung function, bronchial hyperreactivity (BHR), exhaled nitric oxide (F(ENO)), baseline eosinophil cationic protein, peripheral blood eosinophilia and total IgE were investigated.

RESULTS

In the group of asthmatics with EIB, statistically significantly higher baseline concentrations of ET-1 and soluble E-selectin compared with asthmatics with negative exercise test results were revealed. In this group of patients, ET-1, thrombomodulin and soluble E-selectin concentrations significantly increased after exercise. Baseline concentrations of ET-1 as well as an increase in soluble E-selectin concentrations 60 min after exercise showed a statistically significant correlation with baseline eosinophil cationic protein, F(ENO) and BHR. The increase in plasma concentrations of ET-1 15 min after exercise and soluble E-selectin 60 min after exercise showed a statistically significant correlation with the increase in F(ENO) and BHR to histamine 24 h after exercise.

CONCLUSIONS

We suggest that during EIB changes in the function of pulmonary endothelium occur and these changes may influence inflammation of the airway and remodeling in asthmatic patients.

Role of vascular endothelial growth factor in pulmonary endothelial cell injury by exercise challenge in asthmatic patients

This study was designed to examine the role of vascular endothelial growth factor (VEGF) in pulmonary endothelial cell injury by exercise in asthmatics. Post-exercise circulating thrombomodulin (TM) levels were significantly increased in asthmatics. Moreover, the increase in TM levels with exercise was significantly correlated with VEGF level in induced sputum from asthmatics (r = 0.80, p = 0.0007). After inhaled steroid therapy, post-exercise TM levels were significantly decreased, but the increase in TM levels with exercise was also correlated with VEGF level (r = 0.60, p = 0.01). Thus, pulmonary endothelial cells stimulated by VEGF in asthmatic airways may be sensitive to exercise challenge.

Plasma thrombomodulin level in very low birthweight infants at birth

OBJECTIVE

Plasma soluble thrombomodulin level reflects endothelial damage. The plasma thrombomodulin level at birth is increased in asphyxiated full-term infants. There is no report of plasma thrombomodulin level in premature infants. To determine the thrombomodulin level in premature infants and whether it might reflect endothelial damage, we examined the plasma thrombomodulin level in very low birthweight (VLBW) infants at birth.

METHODS

Forty-five VLBW infants, of whom 14 had perinatal asphyxia complications, were recruited. As a control, 50 full-term infants without complications were also studied. Plasma thrombomodulin concentration, pH, base deficit, serum creatinine and D-dimer concentration, platelet count and fibrinogen concentration were measured within 1 hour after birth.

RESULTS

There were significant differences in plasma pH, creatinine concentration, platelet count, antithrombin III activity and D-dimer concentration between VLBW infants and full-term infants. Plasma thrombomodulin concentration (39.0 (16.6-93.7) vs 27.0 (16.6-39.1) microg/L, p < 0.0001) and plasma thrombomodulin-to-serum creatinine ratio (0.82 (0.19-2.65) vs 0.47 (0.24-0.70) microg/micromol, p < 0.0001) were significantly higher in VLBW infants than those in full-term infants. By univariate analyses for all neonates, there were significant relations between plasma thrombomodulin concentration and gestational age, birthweight, plasma pH, creatinine concentration, platelet count and antithrombin III activity. A stepwise multiple linear regression model using the above variables as dependent factors showed only birthweight contributed significantly to plasma thrombomodulin concentration (plasma thrombomodulin concentration (microg/l) = 45.677-0.006 (birthweight; g), r2 = 0.323, p < 0.0001, n = 94). Plasma thrombomodulin concentration and plasma thrombomodulin-to -serum creatinine ratio in VLBW infants with asphyxia were higher than in those without asphyxia, but not significantly different (43.2 +/- 17.7 vs 38.3 +/- 8.5 microg/l and 0.92 +/- 0.60 vs 0.83 +/- 0.37 microg/micromol).

CONCLUSION

Plasma thrombomodulin level in VLBW infants shows a high value at birth, and we consider the main factor responsible for this elevation may be endothelial damage or low clearance rate of thrombomodulin, which may be related to early gestational age.