Alpha1-antitrypsin is an important neutrophil elastase inhibitor that protects lung tissue from the destructive effects of neutrophil elastase released by degranulating neutrophils. In addition to... Show moreAlpha1-antitrypsin is an important neutrophil elastase inhibitor that protects lung tissue from the destructive effects of neutrophil elastase released by degranulating neutrophils. In addition to the liver, local production by macrophages and airway and alveolar epithelial cells may contribute to the formation of an anti-elastase screen in the lung. The Z mutation (E342K) of _1-antitrypsin, compromising over 95% of the _1-antitrypsin deficiency patients, causes subtle misfolding of the protein that permits polymer formation and accumulation within the endoplasmic reticulum (ER) of hepatocytes leading to plasma deficiency. This causes hepatic cirrhosis and early-onset lung emphysema. The discovery of ZZ polymers in broncho-alveolar lavage fluid and pulmonary tissue and their identification many years after liver transplantation led to the proposal that pulmonary pathology could be induced by polymers. Overexpression of Z _1-antitrypsin is known to induce polymer formation, prime cells for an exaggerated ER stress response upon a second hit and initiate NF-_B signalling. However, whether endogenous expression in primary bronchial epithelial cells and monocyte-derived macrophages has similar consequences remained unclear. This thesis concentrate on these specific questions. In addition, we focused on the ER stress response induced by P.aeruginosa as a possible second hit in _1-antitrypsin deficiency Show less
Wout, E.F.A. van 't; Schadewijk, A. van; Savage, N.D.L.; Stolk, J.; Hiemstra, P.S. 2012
Alpha-1 antitrypsin (AAT) acts as an important neutrophil elastase inhibitor in the lung. Although the hepatocyte is considered as the primary source of AAT, local production by monocytes,... Show moreAlpha-1 antitrypsin (AAT) acts as an important neutrophil elastase inhibitor in the lung. Although the hepatocyte is considered as the primary source of AAT, local production by monocytes, macrophages and epithelial cells may contribute to the formation of an anti-elastase screen. Since monocytes can differentiate into a heterogeneous population of macrophages with subpopulations ranging from pro-inflammatory properties (MΦ-1) to anti-inflammatory properties (MΦ-2) and into dendritic cells (DC), we studied whether lipopolysaccharide (LPS), tumor necrosis factor alpha (TNFα) and oncostatin M (OSM) enhance AAT production differentially in cultured MΦ-1, MΦ-2 and DC. Monocytes from healthy blood donors were cultured for 7 days in the presence of GM-CSF, M-CSF, or GM-CSF and IL-4 to obtain MΦ-1, MΦ-2 and immature(i)DC, respectively. Next, cells were stimulated with LPS, TNFα or OSM and synthesis of AAT was assessed by quantitative RT-PCR, immunocytochemistry and ELISA. Spontaneous release of AAT was higher in MΦ-1 than in MΦ-2 and iDC and only LPS significantly increased AAT production in MΦ-1, MΦ-2 and DC, whereas TNFα and OSM did not affect AAT secretion. The secretion levels of the related protease inhibitors alpha-1 antichymotrypsin (ACT) and secretory leucocyte proteinase inhibitor (SLPI) were below the limits of detection by ELISA. In contrast to the protein data, analysis by quantitative RT-PCR showed that 24h LPS exposure caused a maximal 2.1-fold AAT mRNA increase in MΦ-1, a 21-fold increase in MΦ-2 and 11-fold increase in DC. These data suggest that cellular differentiation is a regulator of local AAT production. Show less
