ATP5B Is an Essential Factor for Hepatitis B Virus Entry

The Interactions between Cells and Viruses

Many infectious diseases are caused by life-threatening DNA and RNA viruses and have been reported worldwide, including those caused by emerging and re-emerging viruses [...].

Hepatitis E Virus: What More Do We Need to Know?

Hepatitis E virus (HEV) infection is typically a self-limiting, acute illness that spreads through the gastrointestinal tract but replicates in the liver. However, chronic infections are possible in immunocompromised individuals. The HEV virion has two shapes: exosome-like membrane-associated quasi-enveloped virions (eHEV) found in circulating blood or in the supernatant of infected cell cultures and non-enveloped virions ("naked") found in infected hosts' feces and bile to mediate inter-host transmission. Although HEV is mainly spread via enteric routes, it is unclear how it penetrates the gut wall to reach the portal bloodstream. Both virion types are infectious, but they infect cells in different ways. To develop personalized treatment/prevention strategies and reduce HEV impact on public health, it is necessary to decipher the entry mechanism for both virion types using robust cell culture and animal models. The contemporary knowledge of the cell entry mechanism for these two HEV virions as possible therapeutic target candidates is summarized in this narrative review.

Flagellar hook protein FlgE promotes macrophage activation and atherosclerosis by targeting ATP5B

BACKGROUND AND AIMS

Pseudomonas aeruginosa (P. aeruginosa) infections are strongly linked to the development of cardiovascular disease and atherosclerosis; however, the underlying mechanisms remain unclear. We previously confirmed that the flagellar hook protein FlgE in P. aeruginosa has immunostimulatory effects. This study investigated the effects and mechanisms of action of FlgE on atherogenesis.

METHODS

ApoE-/- mice were intravenously challenged with FlgE or FlgEM recombinant proteins for eight weeks. A murine model of chronic lung colonization was established using beads containing either mutable- or wild-type bacteria. Aortic sinus sections were stained to assess atherosclerosis progression. THP-1 macrophages exposed to FlgE or FlgEM were evaluated for their effects on lipid uptake and inflammation in vitro. Western blotting and pull-down assays were used to identify the binding proteins and signaling pathways involved, and specific blocking experiments were performed to confirm these effects.

RESULTS

FlgE accelerated atherosclerosis progression by triggering lipid deposition and inflammatory responses in high-fat diet (HFD)-fed ApoE-/- mice. In comparison to infection with wild-type PAO1, infection with PAO1/flgEΔBmF resulted in reduced atherosclerosis. Mechanistic analysis indicated that FlgE exacerbated lipoprotein uptake and foam cell formation by upregulating SR-A1 expression. Moreover, FlgE activated NF-κB and MAPK signaling, which subsequently led to inflammatory responses in THP-1-derived macrophages. Pull-down assays revealed that FlgE directly interacted with ATP5B, whereas blocking ATP5B attenuated FlgE-induced responses in macrophages.

CONCLUSIONS

FlgE induces macrophage lipid uptake and pro-inflammatory responses mediated by ATP5B/NF-kB/AP-1 signaling, which eventually results in atherosclerosis. These findings support the development of therapeutic strategies for P. aeruginosa infection-induced atherosclerosis.