AUTHOR=Bazant Jasmin , Weiss Astrid , Baldauf Julia , Schermuly Ralph Theo , Hain Torsten , Lucas Rudolf , Mraheil Mobarak Abu 

TITLE=Pneumococcal hydrogen peroxide regulates host cell kinase activity

JOURNAL=Frontiers in Immunology

VOLUME=15

YEAR=2024

URL=https://www.frontiersin.org/journals/immunology/articles/10.3389/fimmu.2024.1414195

DOI=10.3389/fimmu.2024.1414195

ISSN=1664-3224

ABSTRACT=<sec><title>Introduction</title><p>Protein kinases are indispensable reversible molecular switches that adapt and control protein functions during cellular processes requiring rapid responses to internal and external events. Bacterial infections can affect kinase-mediated phosphorylation events, with consequences for both innate and adaptive immunity, through regulation of antigen presentation, pathogen recognition, cell invasiveness and phagocytosis. <italic>Streptococcus pneumoniae</italic> (<italic>Spn</italic>), a human respiratory tract pathogen and a major cause of community-acquired pneumoniae, affects phosphorylation-based signalling of several kinases, but the pneumococcal mediator(s) involved in this process remain elusive. In this study, we investigated the influence of pneumococcal H<sub>2</sub>O<sub>2</sub> on the protein kinase activity of the human lung epithelial H441 cell line, a generally accepted model of alveolar epithelial cells.</p></sec><sec><title>Methods</title><p>We performed kinome analysis using PamGene microarray chips and protein analysis in Western blotting in H441 lung cells infected with <italic>Spn</italic> wild type (<italic>SpnWT</italic>) or with <italic>SpnΔlctOΔspxB</italic> -a deletion mutant strongly attenuated in H<sub>2</sub>O<sub>2</sub> production- to assess the impact of pneumococcal hydrogen peroxide (H<sub>2</sub>O<sub>2</sub>) on global protein kinase activity profiles.</p></sec><sec><title>Results</title><p>Our kinome analysis provides direct evidence that kinase activity profiles in infected H441 cells significantly vary according to the levels of pneumococcal H<sub>2</sub>O<sub>2</sub>. A large number of kinases in H441 cells infected with <italic>SpnWT</italic> are significantly downregulated, whereas this no longer occurs in cells infected with the mutant <italic>SpnΔlctOΔspxB</italic> strain, which lacks H<sub>2</sub>O<sub>2.</sub> In particular, we describe for the first time H<sub>2</sub>O<sub>2</sub>-mediated downregulation of Protein kinase B (Akt1) and activation of lymphocyte-specific tyrosine protein kinase (Lck) via H<sub>2</sub>O<sub>2</sub>-mediated phosphorylation.</p></sec>