Epigallocatechin gallate inhibits Streptococcus pneumoniae virulence by simultaneously targeting pneumolysin and sortaseA.

Meng Song,Jianfeng Wang,Xiaodi Niu,Meng Li,Xuming Deng,Zihao Teng

doi:10.1111/jcmm.13179

Abstract

Streptococcus pneumoniae (pneumococcus), the causative agent of several human diseases, possesses numerous virulence factors associated with pneumococcal infection and pathogenesis. Pneumolysin (PLY), an important virulence factor, is a member of the cholesterol‐dependent cytolysin family and has cytolytic activity. Sortase A (SrtA), another crucial pneumococcal virulence determinate, contributes greatly to the anchoring of many virulence‐associated surface proteins to the cell wall. In this study, epigallocatechin gallate (EGCG), a natural compound with little known antipneumococcal activity, was shown to directly inhibit PLY‐mediated haemolysis and cytolysis by blocking the oligomerization of PLY and simultaneously reduce the peptidase activity of SrtA. The biofilm formation, production of neuraminidase A (NanA, the pneumococcal surface protein anchored by SrtA), and bacterial adhesion to human epithelial cells (Hep2) were inhibited effectively when S. pneumoniae D39 was cocultured with EGCG. The results from molecular dynamics simulations and mutational analysis confirmed the interaction of EGCG with PLY and SrtA, and EGCG binds to Glu277, Tyr358, and Arg359 in PLY and Thr169, Lys171, and Phe239 in SrtA. In vivo studies further demonstrated that EGCG protected mice against S. pneumoniae pneumonia. Our results imply that EGCG is an effective inhibitor of both PLY and SrtA and that an antivirulence strategy that directly targets PLY and SrtA using EGCG is a promising therapeutic option for S. pneumoniae pneumonia.

Highlights

Streptococcus pneumoniae is the major causative pathogen of community-acquired pneumonia (CAP), which carries a high mortality rate as a result of acute lung injury and multi-organ dysfunction syndrome [1]
Pneumococcus expresses a number of well-characterized virulence factors, including the capsule (Cps), pneumolysin (PLY), sortase A (SrtA), pneumococcal surface protein A (PspA), hyaluronidase (Hyl) and neuraminidases (NanA), which are important in the process of infections [3]
The inhibitory effect of epigallocatechin gallate (EGCG) on SrtA was determined by the fluorescence resonance energy transfer (FRET) assay

Summary

Introduction

Streptococcus pneumoniae (pneumococcus) is the major causative pathogen of community-acquired pneumonia (CAP), which carries a high mortality rate as a result of acute lung injury and multi-organ dysfunction syndrome [1]. Pneumococcal infection causes various diseases, including acute otitis media, pneumonia, sepsis and meningitis, in young children, elderly people and immunocompromised individuals, and asymptomatic carriage is common [2]. Pneumococcus expresses a number of well-characterized virulence factors, including the capsule (Cps), pneumolysin (PLY), sortase A (SrtA), pneumococcal surface protein A (PspA), hyaluronidase (Hyl) and neuraminidases (NanA), which are important in the process of infections [3]. A novel role of PLY in enabling nasopharyngeal colonization by pneumococcus has been demonstrated recently [8]. These findings indicate that PLY is an important candidate as a target for antivirulence drug development

Methods

Results

Conclusion