Key result
In a porcine model, acute liver failure induced a 4-fold increased lung uptake of hyaluronan and a 5-fold increased uptake of tissue plasminogen activator and lysosomal enzymes compared to controls.
In a porcine model, acute liver failure leads to significantly increased pulmonary uptake of harmful macromolecules, suggesting a mechanism for lung damage secondary to liver disease.
Lungs may mediate macromolecule-driven injury in ALF; hypothesis-generating in porcine model and leaves open human translation.
BACKGROUND: Pulmonary complications are common in acute liver failure (ALF). The role of the lungs in the uptake of harmful soluble endogenous macromolecules was evaluated in a porcine model of ALF induced by hepatic devascularization (n = 8) vs. controls (n = 8). In additional experiments, pulmonary uptake was investigated in healthy pigs. Fluorochrome-labeled modified albumin (MA) was applied to investigate the cellular uptake. RESULTS: As compared to controls, the ALF group displayed a 4-fold net increased lung uptake of hyaluronan, and 5-fold net increased uptake of both tissue plasminogen activator and lysosomal enzymes. Anatomical distribution experiments in healthy animals revealed that radiolabeled MA uptake (taken up by the same receptor as hyaluronan) was 53% by the liver, and 24% by the lungs. The lung uptake of LPS was 14% whereas 60% remained in the blood. Both fluorescence and electron microscopy revealed initial uptake of MA by pulmonary endothelial cells (PECs) with later translocation to pulmonary intravascular macrophages (PIMs). Moreover, the presence of PIMs was evident 10 min after injection. Systemic inflammatory markers such as leukopenia and increased serum TNF-α levels were evident after 20 min in the MA and LPS groups. CONCLUSION: Significant lung uptake of harmful soluble macromolecules compensated for the defect liver scavenger function in the ALF-group. Infusion of MA induced increased TNF-α serum levels and leukopenia, similar to the effect of the known inflammatory mediator LPS. These observations suggest a potential mechanism that may contribute to lung damage secondary to liver disease.
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Nedredal et al. (2016) studied Acute liver failure (n=16). Acute liver failure (induced by hepatic devascularization) vs. Controls was evaluated on Lung uptake of hyaluronan, tissue plasminogen activator, and lysosomal enzymes. In a porcine model, acute liver failure induced a 4-fold increased lung uptake of hyaluronan and a 5-fold increased uptake of tissue plasminogen activator and lysosomal enzymes compared to controls.
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