actively modulates TFEB in murine macrophages in a growth-phase and time-dependent manner.

Activation of the host transcription factor TFEB helps mammalian cells adapt to stresses such as starvation and infection by upregulating lysosome, autophagy, and immuno-protective gene expression. Thus, TFEB is generally thought to protect host cells. However, it may also be that pathogenic bacteria like orchestrate TFEB in a spatio-temporal manner to harness its functions to grow intracellularly.

Aggregation and Size Attributes Analysis of Unadsorbed and Adjuvant-adsorbed Antigens using a Multispectral Imaging Flow Cytometer Platform.

Various vaccine quality attributes should be monitored to ensure consistency, potency, purity, and safety of vaccine products prior to lot release. Vaccine particle size and protein antigen aggregation are two important considerations for particle-adsorbed vaccines. In this study, we evaluated the use of imaging flow cytometry as a potential all-in-one platform to measure adjuvant particle size and to detect protein aggregates through a combination of brightfield microscopy, side scatter detection, and fluorescence microscopy.

Anti-FIM and Anti-FHA Antibodies Inhibit Growth and Reduce Epithelial Cell Inflammation Through Bacterial Aggregation.

The pertussis vaccination is highly recommended for infants, children, and pregnant women. Despite a high coverage of vaccination, pertussis continues to be of public health concern as a re-emerging infectious disease. The mechanism by which vaccine-elicited anti-pertussis antibodies mediate direct bactericidal effects is poorly understood.

Lysosome enlargement during inhibition of the lipid kinase PIKfyve proceeds through lysosome coalescence.

Lysosomes receive and degrade cargo from endocytosis, phagocytosis and autophagy. They also play an important role in sensing and instructing cells on their metabolic state. The lipid kinase PIKfyve generates phosphatidylinositol-3,5-bisphosphate to modulate lysosome function.

Phosphoinositide Diversity, Distribution, and Effector Function: Stepping Out of the Box.

Phosphoinositides (PtdInsPs) modulate a plethora of functions including signal transduction and membrane trafficking. PtdInsPs are thought to consist of seven interconvertible species that localize to a specific organelle, to which they recruit a set of cognate effector proteins. Here, in reviewing the literature, we argue that this model needs revision.

The Lipid Kinase PIKfyve Coordinates the Neutrophil Immune Response through the Activation of the Rac GTPase.

Neutrophils rapidly arrive at an infection site because of their unparalleled chemotactic ability, after which they unleash numerous attacks on pathogens through degranulation and reactive oxygen species (ROS) production, as well as by phagocytosis, which sequesters pathogens within phagosomes. Phagosomes then fuse with lysosomes and granules to kill the enclosed pathogens. A complex signaling network composed of kinases, GTPases, and lipids, such as phosphoinositides, helps to coordinate all of these processes.

Quantifying Phagocytosis by Immunofluorescence and Microscopy.

Phagocytosis is the actin-driven internalization of solid particles, utilized by phagocytic immune cells to sequester potentially infectious microorganisms. Aided by the innate and adaptive immune system, the activation of various phagocytic receptors triggers a cascade of downstream signaling mediators that drive actin and plasma membrane remodeling. Modulation of these molecular players can lead to distinct changes in the capacity and rates of phagocytosis.

Phagocytosis Enhances Lysosomal and Bactericidal Properties by Activating the Transcription Factor TFEB.

Macrophages internalize pathogens through phagocytosis, entrapping them into organelles called phagosomes. Phagosomes then fuse with lysosomes to mature into phagolysosomes, acquiring an acidic and hydrolytic lumen that kills the pathogens. During an ongoing infection, macrophages can internalize dozens of bacteria.

Radiolabeling and Quantification of Cellular Levels of Phosphoinositides by High Performance Liquid Chromatography-coupled Flow Scintillation.

Phosphoinositides (PtdInsPs) are essential signaling lipids responsible for recruiting specific effectors and conferring organelles with molecular identity and function. Each of the seven PtdInsPs varies in their distribution and abundance, which are tightly regulated by specific kinases and phosphatases. The abundance of PtdInsPs can change abruptly in response to various signaling events or disturbance of the regulatory machinery.

The Fab1/PIKfyve phosphoinositide phosphate kinase is not necessary to maintain the pH of lysosomes and of the yeast vacuole.

Lysosomes and the yeast vacuole are degradative and acidic organelles. Phosphatidylinositol 3,5-bisphosphate (PtdIns(3,5)P2), a master architect of endolysosome and vacuole identity, is thought to be necessary for vacuolar acidification in yeast. There is also evidence that PtdIns(3,5)P2 may play a role in lysosomal acidification in higher eukaryotes.