Ein stumpfes Thoraxtrauma induziert ausgeprägte Veränderungen der Immunlage der Lunge

Abstract

Introduction: Blunt chest trauma is still associated with a high incidence of infectious complications, most notably pneumonia [1, 2]. This suggests a posttraumatic dysfunction of the bacterial defense in the lung. Toll Like Receptors (TLR) play a central role in the immunosurveillance by recognizing pathogen associated cell wall compounds [3]. The aim of this study was to elucidate changes in the TLR expression in lung tissue and on alveolar macrophages (AM) following blunt chest trauma. Methods: Male wistar rats were randomly allotted to 3 groups, 6 animals each. Two groups were subjected to a blast wave injury and sacrificed 6 (TX-6 h) or 24 hours (TX-24 h) after the trauma, another group served as control. After removal of the right lower lung lobe the AM were harvested. The mRNA expression of TLR2 and TLR4 was determined in the lung tissue and on AM. The number of TLR copies was determined in relation to 106 copies of GAPDH. Results: There was a posttraumatic decrease in TLR expression in lung tissue. TX-24 h animals exhibited 34.09 TLR2/ GAPDH vs. 73.54 TLR2/ GAPDH in controls. The TLR4 expression was also reduced with 4.9 in TX-24 h animals compared to 14.58 TLR4/ GAPDH in controls (p<0.05). Likewise alveolar macrophages displayed a significant reduction in TLR4 expression with 4654 TLR4/ GAPDH in the TX-24 h group compared to 11484 TLR4/ GAPDH in the control group (p<0.05). There was a slight posttraumatic increase in TLR2 expression with 56712 TLR2/ GAPDH in Tx-24 h animals compared to 37810 TLR2/ GAPDH in controls. Discussion: Our results demonstrate for the first time an alteration of TLR 2 and 4 expression in lung tissue as well as on AM following blunt chest trauma. Since the expression of Toll Like Receptors is essential for the host defence against invading microorganisms this downregulation could contribute to the high rate of septic complications following blunt chest trauma.