LPS and TNFa differentially increase intrapulmonary airway and artery contraction in mouse precision cut lung slices

Background: Acute respiratory distress syndrome (ARDS) can result in impaired airway function and increased risk of pulmonary hypertension. In animal models of ARDS, in vivo lipopolysaccharide (LPS) leads to release of inflammatory cytokines, such as tumour necrosis factor-α (TNFα). The direct effects of LPS and TNFa on intrapulmonary airway and artery reactivity have yet to be fully defined. Aims: To assess whether in vitro treatment with LPS or TNFa alters airway and artery contraction in mouse precision cut lung slices (PCLS). Methods: PCLS were prepared from agarose-inflated lungs from male C57BL6 mice, and cultured overnight in the absence (control, C) or presence of 10μg/mL LPS or 10ng/ml TNFα. Contraction of intrapulmonary airways and arteries (80-200μm) to the thromboxane mimetic U46619 or endothelin-1 (ET-1) were assessed in situ. Results: LPS increased airway contraction to ET-1 (maximum % reduction in lumen area (max): C 55±5% n=13; +LPS 77±7% n=8; p<0.05), but not U46619, while TNFα did not alter airway contraction to either agonist. With LPS, there was a trend towards increased vasoconstriction to both ET-1 and U46619 (p=0.08, 0.07). TNFα did not alter artery contraction to ET-1, but vasoconstriction to U46619 was markedly increased (max: C 23±3% n=13; +TNFα 45±10% n=7; p<0.05). Conclusions: The differential effects of inflammatory mediators in PCLS has implications for increased airway and pulmonary vascular resistance. While in vitro LPS exposure increases contraction, this change does not appear to be TNFα-driven. Further studies using PCLS may provide insights into mechanisms underlying altered reactivity relevant to disease settings such as ARDS.