Biology subjects

Vazquez Marrero, V. R.

Publications and source records attributed to Vazquez Marrero, V. R..

4 recordsLinked to original sources

bioRxiv2026

Environmental Amino Acid Sensing Regulates the Rate of ASC Translation and NLRP3 Inflammasome Assembly

The NOD-, LRR-, and pyrin domain-containing protein 3 (NLRP3) inflammasome is a multiprotein signaling complex that triggers pyroptotic cell death and interleukin (IL)-1 family cytokine release during infection and cell injury. Its assembly is driven by the adaptor protein, apoptosis-associated speck-like protein containing a CARD (ASC), whose filamentation forms a supramolecular speck upon NLRP3 activation to amplify inflammasome signaling. While the NLRP3 inflammasome is well appreciated as a sensor of environmental danger and damage, little is known about how homeostatic environmental factors like dietary metabolites regulate its activity. Here, we find that environmental availability of the branched-chain amino acids (BCAAs), leucine, isoleucine, and valine, controls NLRP3 inflammasome assembly. While ASC is typically viewed as a constitutively expressed, unregulated inflammasome component, we find that Toll-like receptor 4 (TLR4) activation triggers localization of ASC mRNA to the perinuclear space. Moreover, our data demonstrate that ASC undergoes TLR4-driven translational bursting from polyribosomes during inflammasome priming. This translational engagement is dependent on BCAA availability and mechanistic target of rapamycin (mTOR) activity, which regulate the kinetics of inflammasome assembly. In contrast, the translation of NLRP3 and caspase-1 is largely insensitive to these inputs. Furthermore, we find that BCAAs regulate NLRP3 inflammasome activation in both mouse and human macrophages, in the context of bacterial infection, and during lipopolysaccharide (LPS)-induced sepsis in vivo. Altogether, this work unveils a novel inflammasome priming event governed by the amino acid environment. These findings further highlight how the activity of proteins maintained in equilibrium like ASC can be dynamically regulated through rapid changes in mRNA translation.

immunology↗

bioRxiv2025

Dendritic cells activate pyroptosis and effector-triggered apoptosis to restrict Legionella infection

The innate immune system relies on pattern recognition receptors (PRRs) to detect pathogen-associated molecular patterns (PAMPs) and guard proteins to monitor pathogen disruption of host cell processes. How different immune cell types engage PRR- and guard protein-dependent defenses in response to infection is poorly understood. Here, we show that macrophages and dendritic cells (DCs) respond in distinct ways to bacterial virulence activities. In macrophages, the bacterial pathogen Legionella pneumophila deploys its Dot/Icm type IV secretion system (T4SS) to deliver effector proteins that facilitate its robust intracellular replication. In contrast, T4SS activity triggers rapid DC death that potently restricts Legionella replication within this cell type. Intriguingly, we found that infected DCs exhibit considerable heterogeneity at the single cell level. Initially, a subset of DCs activate caspase-11 and NLRP3 inflammasome-dependent pyroptosis and release IL-1{beta} early during infection. At later timepoints, a separate DC population undergoes apoptosis driven by T4SS effectors that block host protein synthesis, thereby depleting the levels of the pro-survival proteins Mcl-1 and cFLIP. Together, pyroptosis and effector-triggered apoptosis robustly restrict Legionella replication in DCs. Collectively, our work suggests a model where Mcl-1 and cFLIP guard host translation in DCs, and that macrophages and DCs distinctly employ innate immune sensors and guard proteins to mount divergent responses to Legionella infection.

immunology↗

bioRxiv2024

GM-CSF engages multiple signaling pathways to enhance pro-inflammatory cytokine responses in human monocytes during Legionella infection

The proinflammatory cytokine granulocyte-macrophage colony-stimulating factor (GM-CSF) is required for host defense against a wide range of pathogens. We previously found that GM-CSF enhances inflammatory cytokine production in murine monocytes and is required for in vivo control of the intracellular bacterial pathogen Legionella pneumophila. It is unclear whether GM-CSF similarly augments cytokine production in human monocytes during bacterial infection. Here, we find that GM-CSF enhances inflammatory cytokine expression in Legionella-infected human monocytes by engaging multiple signaling pathways. Legionella- and TLR-dependent NF-B signaling is a prerequisite signal for GM-CSF to promote cytokine expression. Then, GM-CSF-driven JAK2/STAT5 signaling is required to augment cytokine expression in Legionella-infected human monocytes. We also found a role for PI-3K/Akt/mTORC1 signaling in GM-CSF-dependent upregulation of cytokine expression. Finally, glycolysis and amino acid metabolism are also critical for GM-CSF to boost cytokine gene expression in human monocytes during infection. Our findings show that GM-CSF-mediated enhancement of cytokine expression in infected human monocytes is regulated by multiple signaling pathways, thereby allowing the host to fine tune antibacterial immunity.

immunology↗

bioRxiv2022

TNF licenses macrophages to undergo rapid caspase-1, -11, and -8-mediated cell death that restricts Legionella pneumophila infection

The inflammatory cytokine tumor necrosis factor (TNF) is associated with host defense against many intracellular pathogens, including Legionella pneumophila. Legionella causes the severe pneumonia Legionnaires Disease and predominantly affects individuals with a suppressed immune system, such as those receiving therapeutic TNF blockade to treat autoinflammatory disorders. TNF induces pro-inflammatory gene expression, cellular proliferation, and survival signals in certain contexts, but can also trigger programmed cell death in others. It remains unclear, however, which of the many downstream activities of TNF contribute to control of intracellular bacterial pathogens like Legionella. In this study, we demonstrate that TNF signaling licenses macrophages to die rapidly in response to Legionella infection. We find that TNF-licensed cells undergo rapid gasdermin-dependent, pyroptotic death downstream of inflammasome activation. We also find that TNF signaling upregulates components of the inflammasome response, and that the caspase-11 mediated non-canonical inflammasome is the first inflammasome to be activated, with caspase-1 and caspase-8 mediating delayed pyroptotic death. We find that all three caspases are collectively required for optimal TNF-mediated restriction of bacterial replication in macrophages. Furthermore, caspase-8 is required for control of pulmonary Legionella infection. These findings reveal a TNF-dependent mechanism in macrophages for the activation of rapid cell death that is collectively mediated by caspases-1, -8, and -11 and subsequent restriction of Legionella infection.

microbiology↗