An Integrative Omics Approach To Understanding Host Cellular Responses To Treponema Pallidum

Background Treponema pallidum ssp. pallidum (Tp), the causative agent of syphilis, is a highly invasive pathogen that moves throughout the body via the bloodstream and invades organs and tissues to cause the serious sequelae associated with sexually transmitted and congenitally acquired syphilis infections. The endothelium represents a crucial barrier for Tp dissemination, and we hypothesized that Tp alters endothelial structure and signalling. In this study, we apply an integrative omics approach to characterize transcriptomic, proteomic, and immune secretomic responses of endothelial cells to Tp. Methods Endothelial cells were grown in vitro and exposed to viable Tp or a background control lacking the pathogen. For transcriptomic analysis, RNA was harvested from the endothelial cells and sequenced via RNAseq. For proteomic analysis, experimental and control samples grown using stable isotope labeling by amino acids in cell culture (SILAC), total protein was harvested and analyzed via orbitrap fusion tandem mass-spectrometry (LC-MS/MS). For immune secretomic analysis, supernatant from endothelial cells co-incubated with Tp was harvested and analyzed for cytokine content via cytometric bead arrays (CBA) using flow-cytometry. Results RNAseq studies identified genes within immune signalling pathways that are differentially regulated in response to Tp. Proteomic analysis identified several pathways involved in cellular structure and modulation, interleukin signalling, and intracellular signalling. Data from CBA experiments further indicate the ability of Tp to alter endothelial cytokine production and secretion. These data give a novel multi-faceted look into the role and response of the endothelium during Tp infection. Conclusion These studies represent a novel systems-level approach to understanding the molecular mechanisms behind the establishment and persistence of Tp infection. Further, they provide insight into how Tp may induce host cellular changes to enable barrier traversal and immune cell recruitment, and in this way provide information that is relevant to syphilis vaccine design.