Proteasomes in Human Bronchoalveolar Lavage Fluid After Burn and Inhalation Injury

Abstract

Objective To determine whether 26S proteasome is detectable in human bronchoalveolar-lavage fluid (BALF) and whether burn and inhalation injury is accompanied by changes in BALF proteasome content or activity. Methods BALF was obtained on hospital admission from 28 patients with burn and inhalation injury (controls: 10 healthy volunteers). Proteasome concentrations were quantified by ELISA and their native molecular mass was assessed by gel filtration. Proteasome peptidase activity was measured employing a chymotryptic-like peptide substrate in combination with epoxomicin (specific proteasome inhibitor). Results BALF protein was increased in patients (p<0.001) and correlated positively with the degree of inhalation injury. 20S/26S proteasomes were detectable in all BALF by ELISA. Gel filtration confirmed the presence of intact 20S and of 26S proteasome which was stable without soluble ATP/Mg2+. In all BALF chymotryptic-like activity was detectable and could be inhibited with epoxomicin by 60–70% (p<0.01). Absolute amounts of 20S/26S proteasomes and proteasome activity were increased in patients (p<0.001 for all). The relative BALF composition after injury was characterized by increased concentrations of 20S proteasome/mg protein (p=0.0034 vs. volunteers), decreased concentrations of 26S proteasome/mg protein (p=0.041 vs. volunteers) and reduced specific proteasome activity (p=0.044 vs. volunteers). 26S proteasome/mg and specific proteasome activity were even further reduced in patients who developed ventilator-associated pneumonia (p=0.045 and p=0.03 vs. patients without VAP, respectively). Conclusions The present study supports the novel concept that extracellular proteasomes could play a pathophysiological role in the injured lung and suggests that insufficient proteasome function may increase susceptibility for pulmonary complications.

Circulating Proteasomes After Burn Injury

“…Although our previous observations on proteasomes in the extracellular bronchoalveolar space point toward a possible functional role in the lung after blunt trauma or burns,26,27 evidence for a pathophysiologic role of circulating 20S proteasomes has not been provided to date. Therefore, patient group differences in circulating 20S proteasome levels appear less important than the distribution of the individual concentrations, as the latter indicate whether they could be useful as a disease biomarker.…”

Indications of early intubation for patients with inhalation injury

“…Researchers have tried to characterize the severity of inhalation injury, using computed tomography (CT) to identify anatomical changes,7, 8 and the calculation of V/Q ratios to assess gas exchange 9. Others have investigated the possibility of biomarkers in plasma or alveolar fluid to determine the severity of inhalation injury 10, 11, 12. Bronchoscopy is a useful tool to diagnose inhalation injury that allows us to see the patient's bronchial surface directly, and to collect alveolar lavage 13, 14, 15, 16, 17, 18.…”

Genetic variants in the PSMA6, PSMC6 and PSMA3 genes associated with childhood asthma in Latvian and Taiwanese populations

“…Proteasomes, key UPS enzymatic complex possess several types of peptidase, endoribonuclease, protein-chaperone and DNA-helicase activities [8][9][10] allowing strict control and coordination of all steps of gene expression, genes and proteins networks and processes of genome-environment interaction. Insufficient proteasome function was implicated in pathophysiology of various acute and chronic lung diseases and their complications [11][12][13][14] and potentially could be a consequence of particular proteasomal genes structural variations.…”