Die Effekte der Augmentationstherapie auf systemische sowie pulmonale Inflammationsmarker beim hereditären alpha1-Antitrypsinmangel

Background. Alpha1-antitrypsin, also referred to as alpha1-proteinase inhibitor or SERPINA1, is an acute phase protein and one of the most abundant serine protease inhibitors in human plasma. Severe ZZ α1-antitrypsin deficiency (AATD) is one of the proven genetic risk factors which is associated with a predisposition to develop early onset, rapidly progressive COPD where emphysema is a major component. The only specific treatment for AATD consists in the substitution of usually weekly infusion of 3-5 g alpha1-antitrypsin (AAT) (60mg/kg body weight). The major concept behind augmentation therapy with human AAT is to raise the levels of AAT and to protect tissues from destruction by proteases. Whilst biochemical efficacy is generally considered proven, clinical efficacy of AAT augmentation therapy is still debated. Objective. To evaluate effects of Prolastin™ therapy on systemic as well as local cytokine/chemokine levels in PiZZ AAT deficiency-related emphysema patients in vivo as well as in vitro. By doing so the objective was to evaluate potential anti-inflammatory effects as well as functions of AAT that are carried out besides its role in the balance of proteases and antiproteases. Furthermore the objective was to evaluate the effects of substitution therapy on AAT polymers which are of great relevance in the current discussion of the pathogenesis of AAT related disease and their potentially associated pro-inflammatory effects. Materials and methods. We included 24 patients with proven PiZZ genotype. Serum and exhaled breath condensate (EBC) samples from patients without (n=12) and with (n=12) weekly augmentation therapy were collected before, two hours after and on day three after AAT infusion. Concentrations of total and polymeric AAT, cytokines/chemokines and C-reactive protein were determined. Blood neutrophils isolated from 12 PiZZ homozygotic donors and primary epithelial cells were exposed to Prolastin™ or to its monomeric and polymeric fractions and cytokines/chemokines where measured in cell supernatants. Results. AAT serum levels significantly rise directly after augmentation therapy and drop on day 3 but remain significantly higher than before augmentation and are always higher than in non-augmented patients. In augmented patients serum AAT-polymer concentrations significantly rise after substitution and drop to baseline levels on day three. Within a week after augmentation therapy, significant fluctuations in serum levels of especially of IL-8 and MCP-1 but also of IL-6, TNFα and VEGF were observed. When compared to augmented patients, non-augmented patients had higher IL-8 and lower MCP-1 levels, and increased CRP levels in EBC. When added for 3 h to PiZZ neutrophils, 1 mg/ml Prolastin™ and its high molecular fraction significantly reduced, whereas monomers enhanced IL-8 release relative to controls. When stimulating primary epithelial cells with Prolastin™ and its fractions, no significant differences in the secretion of IL-6, IL-8 and MCP-1 where observed. Conclusion. Besides its role in the balance of proteases and antiproteases AAT seems to have an important function the regulation of inflammation. Its strong effects on IL-8 and MCP-1 suggest a function in the recruitment of neutrophil granulocytes and monocytes. Comparing augmented to non-augmented patients, CRP levels in EBC as well as IL-8 peak concentrations are much higher in the non-augmented subgroup which provides further evidence for the overall anti-inflammatory effect of AAT substitution. After substitution serum AAT-polymers rise remarkably. Induction of IL-8 secretion by AAT seems to be one of its pro-inflammatory properties. These are not carried out in the same way by polymers and Prolastin™ as they are by monomeric AAT when stimulating neutrophil granulocytes in vitro. A toxic effect of non-modified AAT polymers on human primary bronchial epithelial cells could not be shown in this study.