High tissue factor in lungs and plasma associates with respiratory morbidity in preterm infants

Aim:  In preterm infants, inflammation and intra-alveolar fibrin formation characterize respiratory distress syndrome (RDS). Tissue factor (TF) is a link between inflammation and coagulation pathways. We investigated the relationship between TF and cytokines in preterm infants to gain information of the role of TF in the inflammatory response. Methods:  We measured TF in plasma and in tracheal aspirates and analysed TF on monocytes by flow cytometry and 13 cytokines from plasma, in 56 preterm infants (birthweight 600–1500 g) during their first week. Results:  Plasma TF increased and peaked on day 3 and correlated with both RDS and inversely with paO2/FIO2. On day 1, TF in tracheal aspirates was 10-fold higher than in plasma and correlated with plasma TF (4888 vs. 506 pg/mL, R = 0.692, p = 0.013, n = 12). Of main pro-inflammatory cytokines, plasma TF correlated post-natally with IL-8 and IL-6 but not with IL-1 or TNF-α. Conclusions:  Respiratory morbidity associates with high TF in lungs and plasma. In sick newborn infants, upregulation of TF may be mediated by IL-6 and IL-8. High TF and pro-inflammatory cytokines may together participate in the pathogenesis of pulmonary and extrapulmonary injury in preterm infants through pro-inflammatory mechanisms.