Transcriptomic analysis of human brain microvascular endothelial cells exposed to laminin binding protein (adhesion lipoprotein) and Streptococcus pneumoniae

Irene Jiménez-Munguía,Petra Majerová,Katarína Bhide,Zuzana Tomečková,Evelína Mochnáčová,Mangesh Bhide

doi:10.1038/s41598-021-87021-4

Abstract

Streptococcus pneumoniae invades the CNS and triggers a strong cellular response. To date, signaling events that occur in the human brain microvascular endothelial cells (hBMECs), in response to pneumococci or its surface adhesins are not mapped comprehensively. We evaluated the response of hBMECs to the adhesion lipoprotein (a laminin binding protein—Lbp) or live pneumococci. Lbp is a surface adhesin recently identified as a potential ligand, which binds to the hBMECs. Transcriptomic analysis was performed by RNA-seq of three independent biological replicates and validated with qRT-PCR using 11 genes. In total 350 differentially expressed genes (DEGs) were identified after infection with S. pneumoniae, whereas 443 DEGs when challenged with Lbp. Total 231 DEGs were common in both treatments. Integrative functional analysis revealed participation of DEGs in cytokine, chemokine, TNF signaling pathways and phagosome formation. Moreover, Lbp induced cell senescence and breakdown, and remodeling of ECM. This is the first report which maps complete picture of cell signaling events in the hBMECs triggered against S. pneumoniae and Lbp. The data obtained here could contribute in a better understanding of the invasion of pneumococci across BBB and underscores role of Lbp adhesin in evoking the gene expression in neurovascular unit.

Highlights

Streptococcus pneumoniae is a life-threatening pathogen responsible for high morbidity and mortality rates worldwide[1]
In order to understand the molecular events in human brain microvascular endothelial cells (hBMECs) occurring due to the adhesion of pneumococcal Lbp, recombinant Lbp was overexpressed in E. coli and purified
Initial quality checks for RNA isolated from induced-hBMECs showed no sign of degradation (Supplementary information Fig. S2), while all cDNA libraries had optimal fragment size between 150 and 300 nt (Supplementary information Fig. S3)

Summary

Introduction

Streptococcus pneumoniae ( known as pneumococcus) is a life-threatening pathogen responsible for high morbidity and mortality rates worldwide[1]. Recent study suggest that the platelet-activating factor receptor (PAFR) plays an important role in the adhesion of S. pneumoniae to endothelial cells, even though pneumococci do not directly bind P AFR6. The Laminin Receptor (LR) has been proposed to mediate binding of S. pneumoniae to the host cells via its choline-binding protein A (CbpA), which may facilitate bacterial internalization[7,8]. Using the high-throughput proteomic approach surface ligands of S. pneumoniae, which bind to the hBMECs were identified[13]. We sought to evaluate the cell response triggered by Lbp in hBMECs. Neuroinvasive bacteria are known to exploit multiple surface proteins to interact with hBMECs and evoke cell signaling events, which facilitate adhesion of pathogen on the endothelial surface and subsequently trigger the translocation (reviewed in[18,19]). It is known that the immune response in pneumococcal meningitis is enhanced by TNF-α, which leads to the activation of NF-κB to regulate pro-inflammatory mediators such as IL-1β, IL-6, IFN- γ and chemokines[2]

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Results

Discussion

Conclusion