Roles and Mechanisms of NLRP3 in Influenza Viral Infection

The footprint of gut microbiota in gallbladder cancer: a mechanistic review

Gallbladder cancer (GBC) is the most common malignant tumor of the biliary system with the worst prognosis. Even after radical surgery, the majority of patients with GBC have difficulty achieving a clinical cure. The risk of tumor recurrence remains more than 65%, and the overall 5-year survival rate is less than 5%. The gut microbiota refers to a variety of microorganisms living in the human intestine, including bacteria, viruses and fungi, which profoundly affect the host state of general health, disease and even cancer. Over the past few decades, substantial evidence has supported that gut microbiota plays a critical role in promoting the progression of GBC. In this review, we summarize the functions, molecular mechanisms and recent advances of the intestinal microbiota in GBC. We focus on the driving role of bacteria in pivotal pathways, such as virulence factors, metabolites derived from intestinal bacteria, chronic inflammatory responses and ecological niche remodeling. Additionally, we emphasize the high level of correlation between viruses and fungi, especially EBV and Candida spp., with GBC. In general, this review not only provides a solid theoretical basis for the close relationship between gut microbiota and GBC but also highlights more potential research directions for further research in the future.

Investigating the Nexus of NLRP3 Inflammasomes and COVID-19 Pathogenesis: Unraveling Molecular Triggers and Therapeutic Strategies

The coronavirus disease 2019 (COVID-19) global pandemic, caused by severe acute respiratory syndrome coronavirus type 2 (SARS-CoV-2), has been marked by severe cases demonstrating a "cytokine storm", an upsurge of pro-inflammatory cytokines in the bloodstream. NLRP3 inflammasomes, integral to the innate immune system, are speculated to be activated by SARS-CoV-2 within host cells. This review investigates the potential correlation between NLRP3 inflammasomes and COVID-19, exploring the cellular and molecular mechanisms through which SARS-CoV-2 triggers their activation. Furthermore, promising strategies targeting NLRP3 inflammasomes are proposed to mitigate the excessive inflammatory response provoked by SARS-CoV-2 infection. By synthesizing existing studies, this paper offers insights into NLRP3 as a therapeutic target, elucidating the interplay between COVID-19 and its pathophysiology. It serves as a valuable reference for future clinical approaches in addressing COVID-19 by targeting NLRP3, thus providing potential avenues for therapeutic intervention.

Regulation and functions of the NLRP3 inflammasome in RNA virus infection

Virus infection is one of the greatest threats to human life and health. In response to viral infection, the host's innate immune system triggers an antiviral immune response mostly mediated by inflammatory processes. Among the many pathways involved, the nucleotide-binding oligomerization domain (NOD)-like receptor protein 3 (NLRP3) inflammasome has received wide attention in the context of viral infection. The NLRP3 inflammasome is an intracellular sensor composed of three components, including the innate immune receptor NLRP3, adaptor apoptosis-associated speck-like protein containing CARD (ASC), and the cysteine protease caspase-1. After being assembled, the NLRP3 inflammasome can trigger caspase-1 to induce gasdermin D (GSDMD)-dependent pyroptosis, promoting the maturation and secretion of proinflammatory cytokines such as interleukin-1 (IL-1β) and interleukin-18 (IL-18). Recent studies have revealed that a variety of viruses activate or inhibit the NLRP3 inflammasome via viral particles, proteins, and nucleic acids. In this review, we present a variety of regulatory mechanisms and functions of the NLRP3 inflammasome upon RNA viral infection and demonstrate multiple therapeutic strategies that target the NLRP3 inflammasome for anti-inflammatory effects in viral infection.

Helenine blocks NLRP3 activation by disrupting the NEK7-NLRP3 interaction and ameliorates inflammatory diseases

BACKGROUND

The involvement of NLRP3 inflammasome is associated with the progress of numerous inflammatory conditions. However, there is currently no single compound used in the clinic. Search for the inhibitor of NLRP3 inflammasome from natural products is an attractive direction. The compound Helenin (Hel), which is obtained from Inula helenium L., is reported to have anti-inflammatory activities. However, the underlying molecular mechanisms and specific inflammatory signal pathway remains not well understood.

PURPOSE

This research aims to determine the impacts of Hel on NLRP3 inflammasome and the underlying mechanism involved, meanwhile also assessing its potential as a therapeutic intervention for inflammatory diseases mediated by NLRP3 overactivation.

METHODS

Pretreated with Hel in BMDMs (bone marrow-derived macrophages), then stimulated with NLRP3 triggers and measured the expression of active caspase-1 and interleukin 1β (IL-1β). Determination of intracellular K+ and Ca2+, ASC oligomerization and mitochondrial reactive oxygen species (mtROS) production were employed to explore the preliminary mechanism of Hel on NLRP3 activation. Subsequently, Co-immunoprecipitation was used to investigate protein-protein interaction and reduction of covalent bonds of Hel was to explore the binding mode between drugs and proteins. Finally, in vivo experiments, we utilized mouse lethal sepsis and monosodium urate(MSU)-induced peritonitis models to evaluate the effectiveness of Hel in inhibiting inflammatory diseases.

RESULTS

The findings revealed that Hel exhibited a specific blocking effect on NLRP3, with no impact on the assembly of NLRC4 and AIM2 inflammasome. Through the analysis of mechanisms targeting key upstream factors in NLRP3 activation, Hel inhibited NLRP3-dependent ASC oligomerization but did not regulating inflammasome priming, K+ efflux, Ca2+ influx, or mitochondrial damage and mtROS. Moreover, Hel effectively interrupted the binding of NEK7-NLRP3, which was dependent on the active double C=C of the α,β-unsaturated carbonyl units in Hel. In mouse models, Hel showed promising therapeutic effects in the treatment of NLRP3 overactivation-associated diseases, including the lethal sepsis and acute systemic inflammation induced by lipopolysaccharide (LPS) and peritonitis induced by MSU.

CONCLUSION

Our results indicate that Hel dependent α,β-unsaturated carbonyl units interrupt the formation of the NLRP3-NEK7 interaction, thereby blocks the inflammasome assemblage and activation. These fundings would suggest that Hel is a promising inhibitor for treating diseases driven by NLRP3 overactivation.