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Table 3 In vitro studies demonstrating the impact of inflammatory mediators on surfactant function

From: Surfactant alteration and replacement in acute respiratory distress syndrome

Mediator

Effects

Phospholipases

 

   PL-A2, PL-C

Generation of lysophospholipids [94]

 

Generation of free fatty acids [95]

 

Loss of surface activity [94]

 

Higher sensitivity towards inhibition by plasma proteins [96]

Cytokines

 

   TNF-α

Pretranslational inhibitory effect on the expression of SP-A and SP-B [97]

Proteases

 

   Elastase

Degradation of SP-A, indirect evidence for degradation of SP-B and SP-C; loss of surface activity [98]

 

Degradation of SP-A, SP-B, SP-C [99]

   Trypsin

Degradation of SP-A [99]

   Surfactant 'convertase'

Increased conversion of large to small surfactant aggregates [32]

Oxygen radicals

 

   ROS, ozone

Decrease in surface activity [100, 101]

 

Induction of lipid peroxidation [101]

 

Inhibition of SP-A self-aggregation [102]

Lipid mediators

 

   Arachidonic acid

Decrease in surface activity [101]

   Activated neutrophils (PMNs)

Decrease in surface activity [100]

 

Degradation of SP-A [100]

  1. PL-A2/-C = phospholipase-A2/-C; PMNs = polymorphonuclear neutrophils; ROS = reactive oxygen species; TNF = tumor necrosis factor.