Medizinische Universität Graz Austria/Österreich - Forschungsportal - Medical University of Graz
Gewählte Publikation:
Balazs, I.
Pathophysiological basis of neutrophil dysfunction in different chronic liver diseases
PhD-Studium (Doctor of Philosophy); Humanmedizin; [ Dissertation ] Medical University of Graz; 2021. pp. 179
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- Autor*innen der Med Uni Graz:
- Balazs Irina
- Betreuer*innen:
- Horvath Angela
- Sattler Wolfgang
- Stadlbauer-Köllner Vanessa
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- Abstract:
- Liver cirrhosis is the end stage of all chronic liver diseases, often complicated by bacterial infections. The innate immune response, in particular neutrophil response, is impaired in cirrhotic patients, leading to the development of infectious complications and higher risk of mortality. Yet unidentified serum components were discussed to promote neutrophil dysfunction in liver cirrhosis. Bile acids (BA) have been recently found to play role in function regulation of several types of immune cells. The impact of BAs on neutrophil function in patients with liver cirrhosis has not been studied in detail yet. This study aimed to investigate, if changes in serum BA composition can contribute to the cirrhosis-associated neutrophil dysfunction. Additionally, possible signalling pathways of BAs in neutrophils, BA and gut microbiome interactions and other, potentially associated with neutrophil dysfunction serum factors, were studied. Serum BAs were measured by HPLC-HRMS. Neutrophil functions were measured by flow cytometry, chemiluminescence, immunofluorescent microscopy and with ChemoTx plates and ibidi µ-slides. BA receptors expression was analyzed by RT-qPCR and flow cytometry. For gut microbiome analysis Illumina MiSeq sequencing technique was used. Serum proteome was analysed by 2D gel electrophoresis. The analysis of serum BAs and circulating neutrophil function in the cohorts of cirrhotic patients (n=109) and healthy controls (n=21) showed the association of higher total chenodeoxycholic acid (CDCA) relative abundance (RA) with impaired neutrophil phagocytosis and the association of lower unconjugated ursodeoxycholic acid (UDCA) RA with impaired neutrophil phagocytosis and ROS production. Neutrophils from healthy donors exhibited increased basal ROS production, when directly treated with total lithocholic acid (LCA), but decreased ROS production in response to stimulation with fMLF after being treated with total CDCA or total LCA and in response to stimulation with E. coli after being treated with total CDCA or total deoxycholic acid (DCA). Total CDCA and total DCA reversibly decreased neutrophil phagocytosis of E. coli. All BAs, except for cholic acid (CA), its conjugates and unconjugated UDCA, inhibited chemotaxis of neutrophils towards fMLF. Unconjugated LCA, CDCA and UDCA delayed neutrophil apoptosis. Gallbladder bile of cirrhotic patients, but not healthy bile induced NETs formation. Neutrophils expressed FPR1, VDR and TGR5 BA receptors. Serum BA composition was significantly associated with gut microbiome composition in cirrhotic patients. Haptoglobin was the most downregulated protein in serum of patients with HCV-associated cirrhosis. Albumin intervention in cirrhotic patients did not cause a stable improvement in neutrophil function. Serum ferritin and heme were not associated with neutrophil function. pANCA, but not other autoantibodies (cANCA, ANA), promoted NETs formation. In summary, this study identifies serum BAs, as well as haptoglobin and pANCA as potential contributors to neutrophil dysfunction in liver cirrhosis. Therefore, therapeutic approaches aimed at modification of serum BA composition, may be potential ways to prevent and treat neutrophil dysfunction and bacterial infections in liver cirrhosis.