Heterogeneity and Compositional Diversities of Campylobacter jejuni Outer Membrane Vesicles (OMVs) Drive Multiple Cellular Uptake Processes

Abstract

Naturally secreted outer membrane vesicles (OMVs) from gut microbes carry diverse cargo, including proteins, nucleic acids, toxins, and many unidentified secretory factors. Bacterial OMVs can shuttle molecules across different cell types as a generalized secretion system, facilitating bacterial pathogenicity and self-survival. Numerous mucosal pathogens, including Campylobacter jejuni (C. jejuni), share a mechanism of harmonized secretion of major virulence factors. Intriguingly, as a common gut pathogen, C. jejuni lacks some classical virulence-associated secretion systems; alternatively, it often employs nanosized lipid-bound OMVs as an intensive strategy to deliver toxins, including secretory proteins, into the target cells. To better understand how the biophysical and compositional attributes of natural OMVs of C. jejuni regulate their cellular interactions to induce a biologically relevant host response, we conducted an in-depth morphological and compositional analysis of naturally secreted OMVs of C. jejuni. Next, we focused on understanding the mechanism of host cell-specific OMVs uptake from the extracellular milieu. We showed that intracellular perfusion of OMVs is mediated by cytosolic as well as multiple endocytic uptake processes due to the heterogenic nature, abundance of surface proteins, and membrane phospholipids acquired from the source bacteria. Furthermore, we used human and avian cells as two different host targets to provide evidence of target cell-specific preferential uptake of OMVs. Together, the present study provides insight into the unique functionality of natural OMVs of C. jejuni at the cellular interface, upholding their potential for multimodal use as prophylactic and therapeutic carriers.

Targeted Bioimaging of Microencapsulated Recombinant LAB Vector Expressing Fluorescent Reporter Protein: A Non-invasive Approach for Microbial Tracking

“…Cells were isolated after the suspension had been filtered through a cell strainer (40 μm) and centrifuged at 500 g for 10 min at RT. Isolated primary CEICs were maintained in RPMI 1640 (Gibco, Invitrogen) medium supplemented with 10% FBS, 100 IU/mL penicillin, and 100 μg/mL streptomycin at 37 °C with 5% CO 2 for 4–6 days until confluency reached to 70–80% …”

Extracellular vesicles in the pathogenesis of Campylobacter jejuni

“…In brief, proteomic analyses of BEV content have confirmed that numerous virulence factors, representing all steps of C. jejuni pathogenesis, are packed into these vesicles [52], [62]. [69]. They reported that host cell-specific differences in BEV uptake from the extracellular milieu were mediated by heterogeneity in vesicles caused by underlying differences in the membrane phospholipids acquired from the source bacteria and the abundance of surface proteins.…”