Journal: bioRxiv

Article Title: Sorafenib, a clinically approved kinase inhibitor attenuates Streptococcus pneumoniae pathogenesis in vivo by targeting serine/threonine kinase StkP

doi: 10.1101/2025.08.14.670243

Figure Lengend Snippet: (A-B). Growth kinetics of wild-type S. pneumoniae strains, ( A ) TIGR4 (T4) and ( B ) D39, showing dose-dependent inhibition of growth with increasing concentrations of sorafenib (SFN). Equimolar concentrations of DMSO (solvent) and untreated bacteria served as negative controls. ** indicates p ≤ 0.01 and **** indicates p ≤ 0.0001 relative to DMSO; ns denotes non-significance by Mann-Whitney test. (C). Percentage viability of erythromycin (ERY) and penicillin (PEN) resistant and sensitive clinical strains of S. pneumoniae upon treatment with different concentrations of SFN. R denotes resistant, S-sensitive and I-intermediate following the CLSI criteria. (D). Confocal microscopy images of D39-gfp-stkP(P Zn ) strain showing the localization of GFP-StkP at the division septum upon induction with 0.5 mM ZnCl 2 and 0.05 mM MnCl 2 compared to uninduced condition. Inset shows magnification of selected region. Scale bars, 5 µm. (E, F). Growth kinetics of D39-gfp-stkP(P Zn ) and D39ΔstkP::gfp-stkP(P Zn ) respectively, upon treatment with 0.5 and 1 µM of SFN in both uninduced and induced conditions. ** indicates p ≤ 0.01 and **** indicates p ≤ 0.0001 comparing uninduced/induced SFN treated bacteria to the respective untreated bacteria; ns denotes non-significance by Mann-Whitney test. All data are representative of mean ± SEM from three independent experiments.

Article Snippet: The encapsulated strains of S. pneumoniae serotype 4, TIGR4 (T4; ATCC BAA-334) and serotype 2, D39 (NCTC 7466) were kindly gifted by Prof. Birgitta Henriques Normark, Karolinska Institutet, Stockholm.

Techniques: Inhibition, Solvent, Bacteria, MANN-WHITNEY, Confocal Microscopy

Journal: bioRxiv

Article Title: Sorafenib, a clinically approved kinase inhibitor attenuates Streptococcus pneumoniae pathogenesis in vivo by targeting serine/threonine kinase StkP

doi: 10.1101/2025.08.14.670243

Figure Lengend Snippet: (A). Flow cytometry histograms of A549 pneumocytes infected with GFP-expressing S. pneumoniae TIGR4 strain-(T4-GFP) strain grown in the presence or absence of 10 μM sorafenib (SFN). Treatment with equimolar concentrations of DMSO served as control. (B) Quantification of percentage of GFP positive infected cells in panel A showing reduced infection of A549 cells by SFN treated bacteria. * indicates p ≤ 0.05; ** indicates p ≤ 0.01; ns denotes non-significance by Welch’s t-test. (C). Viability staining of TIGR4 strain treated with 10 μM SFN using SYTO9 and PI dyes showing differential staining of live (green) and dead (red and green) bacteria. Scale bars, 5 µm. (D, E). Scanning electron microscopy of ( D ) 10 μM DMSO (solvent) and ( E ) SFN treated bacteria showing areas of compromised cell wall. Inset shows magnification of regions selected. Magnification 100,000x. Scale bars, 1 µm. (F). Flow cytometry histogram and ( G ) quantification analysis of complement C3 protein deposition on 10 μM SFN treated T4 bacteria upon incubation with normal healthy serum (NHS). Heat inactivated serum (HI-NHS) was used as negative control. Capsule permeabilized bacteria that were opsonized with anti- Streptococcus pneumoniae antibody was used as the positive control. ** indicates p ≤ 0.01 and ns denotes non-significance by Paired normal t-test. All data and images are representative of mean ± SEM from three independent experiments.

Article Snippet: The encapsulated strains of S. pneumoniae serotype 4, TIGR4 (T4; ATCC BAA-334) and serotype 2, D39 (NCTC 7466) were kindly gifted by Prof. Birgitta Henriques Normark, Karolinska Institutet, Stockholm.

Techniques: Flow Cytometry, Infection, Expressing, Control, Bacteria, Staining, Electron Microscopy, Solvent, Incubation, Negative Control, Positive Control

Journal: bioRxiv

Article Title: Sorafenib, a clinically approved kinase inhibitor attenuates Streptococcus pneumoniae pathogenesis in vivo by targeting serine/threonine kinase StkP

doi: 10.1101/2025.08.14.670243

Figure Lengend Snippet: (A). Schematic showing the experimental workflow for testing the efficacy of sorafenib in six-to nine-week-old male C57BL/6 mice infected with 1×10 6 CFU of TIGR4 strain via oropharyngeal route, followed by treatment with sorafenib (SFN) (10 mg/kg) intravenously at 1 h post infection and intraperitoneally at 24 h intervals. Infected mice treated with the solvent, 55% PEG-400 and 20% DMSO was used as the placebo control. (B). Survival curve of C57BL/6 mice (n=11) infected with T4 strain and treated with SFN or placebo over 4 days post infection. Infected mice were scored for clinical symptoms daily and were sacrificed upon reaching the ethical end point. * indicates p ≤ 0.05 by Mantel-Cox test. (C). Bacterial CFU (in million) recovered from the lungs of infected mice ( n =5 for placebo; n=7 for SFN) was measured post-sacrifice and expressed normalized per million of input bacteria. ** indicates p ≤ 0.01 by Mann-Whitney test. Data are representative of mean ± SEM.

Article Snippet: The encapsulated strains of S. pneumoniae serotype 4, TIGR4 (T4; ATCC BAA-334) and serotype 2, D39 (NCTC 7466) were kindly gifted by Prof. Birgitta Henriques Normark, Karolinska Institutet, Stockholm.

Techniques: Infection, Solvent, Control, Bacteria, MANN-WHITNEY