Proteomic Profiling of Outer Membrane Vesicles Released by Escherichia coli LPS Mutants Defective in Heptose Biosynthesis

The proteome of bacterial membrane vesicles in Escherichia coli-a time course comparison study in two different media

Introduction

Bacteria inhabit the in- and outside of the human body, such as skin, gut or the oral cavity where they play an innoxious, beneficial or even pathogenic role. It is well known that bacteria can secrete membrane vesicles (MVs) like eukaryotic cells with extracellular vesicles (EVs). Several studies indicate that bacterial membrane vesicles (bMVs) play a crucial role in microbiome-host interactions. However, the composition of such bMVs and their functionality under different culture conditions are still largely unknown.

Methods

To gain a better insight into bMVs, we investigated the composition and functionality of E. coli (DSM 105380) bMVs from the culture media Lysogeny broth (LB) and RPMI 1640 throughout the different phases of growth (lag-, log- and stationary-phase). bMVs from three time points (8 h, 54 h, and 168 h) and two media (LB and RPMI 1640) were isolated by ultracentrifugation and analyzed using nanoparticle tracking analysis (NTA), cryogenic electron microscopy (Cryo-EM), conventional transmission electron microscopy (TEM) and mass spectrometry-based proteomics (LC-MS/MS). Furthermore, we examined pro-inflammatory cytokines IL-1β and IL-8 in the human monocyte cell line THP-1 upon bMV treatment.

Results

Particle numbers increased with inoculation periods. The bMV morphologies in Cryo-EM/TEM were similar at each time point and condition. Using proteomics, we identified 140 proteins, such as the common bMV markers OmpA and GroEL, present in bMVs isolated from both media and at all time points. Additionally, we were able to detect growth-condition-specific proteins. Treatment of THP-1 cells with bMVs of all six groups lead to significantly high IL-1β and IL-8 expressions.

Conclusion

Our study showed that the choice of medium and the duration of culturing significantly influence both E. coli bMV numbers and protein composition. Our TEM/Cryo-EM results demonstrated the presence of intact E. coli bMVs. Common E. coli proteins, including OmpA, GroEL, and ribosome proteins, can consistently be identified across all six tested growth conditions. Furthermore, our functional assays imply that bMVs isolated from the six groups retain their function and result in comparable cytokine induction.

Fusobacterium nucleatum outer membrane vesicles activate autophagy to promote oral cancer metastasis

INTRODUCTION

Metastasis is an important cause of high mortality and lethality of oral cancer. Fusobacterium nucleatum (Fn) can promote tumour metastasis. Outer membrane vesicles (OMVs) are secreted by Fn. However, the effects of Fn-derived extracellular vesicles on oral cancer metastasis and the underlying mechanisms are unclear.

OBJECTIVES

We aimed to determine whether and how Fn OMVs mediate oral cancer metastasis.

METHODS

OMVs were isolated from brain heart infusion (BHI) broth supernatant of Fn by ultracentrifugation. Tumour-bearing mice were treated with Fn OMVs to evaluate the effect of OMVs on cancer metastasis. Transwell assays were performed to determine how Fn OMVs affect cancer cell migration and invasion. The differentially expressed genes in Fn OMV-treated/untreated cancer cells were identified by RNA-seq. Transmission electron microscopy, laser confocal microscopy, and lentiviral transduction were used to detect changes in autophagic flux in cancer cells stimulated with Fn OMVs. Western blotting assay was performed to determine changes in EMT-related marker protein levels in cancer cells. Fn OMVs' effects on migration after blocking autophagic flux by autophagy inhibitors were determined by in vitro and in vivo experiments.

RESULTS

Fn OMVs were structurally similar to vesicles. In the in vivo experiment, Fn OMVs promoted lung metastasis in tumour-bearing mice, while chloroquine (CHQ, an autophagy inhibitor) treatment reduced the number of pulmonary metastases resulting from the intratumoral Fn OMV injection. Fn OMVs promoted the migration and invasion of cancer cells in vivo, leading to altered expression levels of EMT-related proteins (E-cadherin downregulation; Vimentin/N-cadherin upregulation). RNA-seq showed that Fn OMVs activate intracellular autophagy pathways. Blocking autophagic flux with CHQ reduced in vitro and in vivo migration of cancer cells induced by Fn OMVs as well as reversed changes in EMT-related protein expression.

CONCLUSION

Fn OMVs not only induced cancer metastasis but also activated autophagic flux. Blocking autophagic flux weakened Fn OMV-stimulated cancer metastasis.

Effects of Adding Extracorporeal Shockwave Therapy (ESWT) to Platelet-Rich Plasma (PRP) among Patients with Rotator Cuff Partial Tear: A Prospective Randomized Comparative Study

A rotator cuff tear is a prevalent ailment affecting the shoulder joint. The clinical efficacy of combined therapy remains uncertain for partial rotator cuff tears. In this study, we integrated extracorporeal shockwave therapy (ESWT) with platelet-rich plasma (PRP) injection, juxtaposed with PRP in isolation. Both cohorts exhibited significant improvements in visual analogue scale (VAS), Constant-Murley score (CMS), degrees of forward flexion, abduction, internal rotation, and external rotation, and the sum of range of motion (SROM) over the six-month assessment period. The application of ESWT in conjunction with PRP exhibited notable additional enhancements in both forward flexion (p = 0.033) and abduction (p = 0.015) after one month. Furthermore, a substantial augmentation in the range of shoulder motion (SROM) (p < 0.001) was observed after six months. We employed isobaric tag for relative and absolute quantitation (iTRAQ) to analyze the differential plasma protein expression in serum samples procured from the two groups after one month. The concentrations of S100A8 (p = 0.042) and S100A9 (p = 0.034), known to modulate local inflammation, were both lower in the ESWT + PRP cohort. These findings not only underscore the advantages of combined therapy but also illuminate the associated molecular changes.