Isolation of Outer Membrane Vesicles from Helicobacter pylori

Studies on the mechanisms of Helicobacter pylori inhibition by Syzygium aromaticum aqueous extract

BACKGROUND

The aqueous extract of the dried buds of Syzygium aromaticum (SAAE) have the potential to alleviate Helicobacter pylori infection, but the specific molecular mechanism has not been fully elucidated.

PURPOSE

This study aimed to investigate the underlying mechanisms of SAAE on H. pylori pathogenicity.

METHODS

The inhibitory kinetics and anti-H. pylori adhesive capacity assays were conducted to examine the effects of SAAE on the growth and adhesive capability of H. pylori. The H. pylori outer membrane vesicles (OMVs) were purified from the culture supernatant through high-speed centrifugation, filtration, and two rounds of ultracentrifugation. Their characteristics and protein composition were then identified using transmission electron microscopy (TEM), nanoparticle tracking analysis (NTA), and qualitative proteomics study. Subsequently, the effect of SAAE on the pathogenicity of H. pylori OMVs was investigated using the Griess reagent assay, enzyme-linked immunosorbent assay (ELISA), quantitative proteomics study, TEM, and western blotting assay.

RESULTS

SAAE exhibited inhibitory effects on H. pylori growth and adhesion. The isolated H. pylori OMVs showed particle size of 27-242 nm and Zeta potential of -9.67 ± 0.53 mV. A total of 599 proteins were identified in the OMVs. Proteomics study indicated that the differential expressed proteins induced by OMVs with or without SAAE commonly enriched in P53 and autophagy pathways. Besides, SAAE counteracted the increased production of pro-inflammatory cytokines and attenuated the induction of cell autophagy caused by H. pylori OMVs. Furthermore, SAAE normalized the abnormal regulation of downstream targets (AIFM2 and IGFBP3) in the P53 signaling pathway caused by H. pylori OMVs.

CONCLUSION

SAAE can inhibit the growth and adhesion of H. pylori, reduce the inflammation and autophagy induced by H. pylori OMVs, and combated the abnormal regulation of P53 signaling pathway caused by H. pylori OMVs. These findings may help elucidate the mechanisms through which SAAE reduces the pathogenicity of H. pylori.

Outer Membrane Vesicles: An Emerging Vaccine Platform

Vaccine adjuvants are substances that improve the immune capacity of a recombinant vaccine to a great extent and have been in use since the early 1900s; they are primarily short-lived and initiate antigen activity, mainly an inflammatory response. With the developing technologies and innovation, early options such as alum were modified, yet the inorganic nature of major vaccine adjuvants caused several side effects. Outer membrane vesicles, which respond to the stressed environment, are small nano-sized particles secreted by gram-negative bacteria. The secretory nature of OMV gives us many benefits in terms of infection bioengineering. This article aims to provide a detailed overview of bacteria's outer membrane vesicles (OMV) and their potential usage as adjuvants in making OMV-based vaccines. The OMV adjuvant-based vaccines can be a great benefactor, and there are ongoing trials for formulating OMV adjuvant-based vaccines for SARS-CoV-2. This study emphasizes engineering the OMVs to develop better versions for safety purposes. This article will also provide a gist about the advantages and disadvantages of such vaccines, along with other aspects.

Bacterial membrane vesicles in inflammatory bowel disease

Inflammatory bowel disease (IBD) is characterized by chronic intestinal inflammation with no cure. The intestine is fundamental in controlling human health. Disruption of the microbial ecosystem in the intestine is considered an important cause of IBD. The interaction between the host and microbiota significantly impacts the intestinal epithelial barrier and immune function. Bacterial membrane vesicles (MVs) are vital participants in bacteria-bacteria and host-microbiota communication. Currently, MVs have been found to exhibit many important regulating effects for intestinal microecology and have excellent application potential in clinical disease therapies. In the present review, we review the current knowledge on MVs, and specifically focus on gut bacterial MVs and their roles in the IBD. In addition, we summarized the potential utility of MVs as a novel therapeutic approach in IBD patients.