Pneumologie 2015; 69 - A5
DOI: 10.1055/s-0035-1548635

IL-1beta release in human lung tissue and mononuclear cells is dependent on pneumococcal pneumolysin

DG Fatykhova 1, A Rabes 1, C Machnik 1, A Becher 1, J Berg 1, M Toennies 2, TB Torsten 2, P Schneider 3, J Rueckert 4, J Neudecker 4, N Suttorp 1, S Hippenstiel 1, B Opitz 1, AC Hocke 1
  • 1Department of Internal Medicine/Infectious Diseases and Pulmonary Medicine, Charité – Universitätsmedizin Berlin, Berlin
  • 2Lungenklinik Heckeshorn, HELIOS Klinikum Emil von Behring, Berlin
  • 3Department for General and Thoracic Surgery, DRK Clinics, Berlin
  • 4Department of General, Visceral, Vascular and Thoracic Surgery, Charité – Universitätsmedizin Berlin, Berlin

Streptococcus pneumoniae (S.p.) is a major cause of pneumonia, bacteremia, sepsis and meningitis worldwide. More than 90 S.p. serotypes are classified, which greatly differ in invasiveness, colonization and disease severity. One major virulence factor of S.p. is pneumolysin (PLY), a cholesterol-dependent pore-forming toxin with cytolytic effects. Recent research revealed that differences in its hemolytic activity contribute to carriage prevalence of bacteria and, moreover, may be highly relevant for the regulation of lung injury. PLY induces immune responses by enhancing cytokine secretion, including NLRP3 inflammasome dependent IL-1beta. Peripheral blood mononuclear cells and human lung tissue were infected with different S.p. serotypes for 16 and 24 hours respectively. Secreted IL-1beta and LDH were measured in the supernatant. Pro-IL-1beta production was evaluated in WB and q-PCR. We demonstrate that infection with S.p. serotypes, expressing hemolytic PLY, induce an immense IL-1beta and LDH production, whereas non-hemolytic S.p. clinical isolates induce less NLRP3 activation and subsequent IL-1beta release in human lung tissue and mononuclear cells. S. pneumoniae D39 wild-type, expressing hemolytic PLY, leads to pro-IL-1beta production with its following cleavage and secretion. In contrast, pro-IL-1beta production through the activation of NF-kB pathway, depended on infection with S.p. delta PLY mutant, doesn't undergo subsequent cleavage and release. Stimulation with hemolytic PLY allele 1 and non-hemolytic allele 5 correlate with results, described previously with bacteria. However, no differences in other cytokine levels, e.g. IL-8, were observed. These data show that the hemolytic activity of PLY results in different immune responses to infection with different S.p. serotypes. Furthermore, hemolytic PLY can be characterized as the main trigger of NLRP3 inflammasome activation and IL-1beta production, even in human lung tissue.