Related Experiment Video

Updated: Dec 20, 2025

Legionella pneumophila Outer Membrane Vesicles: Isolation and Analysis of Their Pro-inflammatory Potential on Macrophages
08:34

Legionella pneumophila Outer Membrane Vesicles: Isolation and Analysis of Their Pro-inflammatory Potential on Macrophages

Published on: February 22, 2017

11.7K

Macrolets: Outsized Extracellular Vesicles Released from Lipopolysaccharide-Stimulated Macrophages that Trap and Kill

Wei Ding1, Olivia C Rivera2, Shannon L Kelleher3

  • 1Department of Surgery, Penn State College of Medicine and Milton S. Hershey Medical Center, Room# C4810, H149, 500 University Drive, Hershey, PA 17033, USA.

Iscience
|May 23, 2020
PubMed

Insights

Researchers discovered "macrolets," a new type of extracellular vesicle released by macrophages. These macrolets, larger than exosomes, trap and kill bacteria like E. coli, offering insights into infection and inflammation.

Area of Science:

  • Immunology
  • Cell Biology
  • Microbiology

Background:

  • Macrophages are known to release various extracellular vesicles (EVs).
  • The specific mechanisms by which macrophages amplify their activities during infection and inflammation are not fully understood.

Purpose of the Study:

  • To identify and characterize a novel class of macrophage-derived extracellular vesicles.
  • To investigate the functional role of these newly discovered EVs in response to bacterial endotoxin.

Main Methods:

  • Macrophage stimulation with lipopolysaccharide (LPS) from Escherichia coli.
  • Morphological and biochemical characterization of released EVs using microscopy and biochemical assays.
  • Assessment of macrolet's capacity to trap and kill E. coli and associated reactive oxygen species production.

Main Results:

  • A new class of EVs, termed "macrolets," were identified, released from macrophages stimulated by LPS.
  • Macrolets are large (10-30 μm), anuclear, single-membraned vesicles dependent on actin cytoskeleton, distinct from exosomes.
  • Macrolets are enriched in tetraspanins, interleukin-6 (IL-6), and IL-6 receptor (IL-6R), and can trap and kill E. coli via reactive oxygen species.

Conclusions:

  • Macrolets represent a previously unreported mechanism for macrophages to combat bacterial infections.
  • These findings suggest macrolets play a significant role in amplifying macrophage functions at sites of infection, inflammation, and healing.
Keywords:
Biological SciencesCell BiologyImmune ResponseImmunologySpecialized Functions of Cells

More Related Videos

Bone Marrow-derived Macrophage Production07:06

Bone Marrow-derived Macrophage Production

Published on: November 22, 2013

74.9K
Scalable Isolation and Purification of Extracellular Vesicles from Escherichia coli and Other Bacteria09:56

Scalable Isolation and Purification of Extracellular Vesicles from Escherichia coli and Other Bacteria

Published on: October 13, 2021

4.5K

Related Concept Videos

Immune Surveillance by NK Cells and Phagocytes01:25

Immune Surveillance by NK Cells and Phagocytes

Immune surveillance is an integral part of the innate immune system, involving the continuous monitoring of peripheral tissues to detect and respond to pathogens, infected cells, or cancerous cells. This surveillance is conducted primarily by natural killer (NK) cells and phagocytes, which employ distinct but complementary mechanisms to identify and eliminate threats.
Natural Killer Cells: The Fast Responders
NK cells are large granular lymphocytes found in the blood and lymphatic system. These...
7.6K
Formation of Lipopolysaccharides01:19

Formation of Lipopolysaccharides

Lipopolysaccharides (LPS) are crucial components of the outer membrane of Gram-negative bacteria, serving both structural and functional roles. It contributes to membrane stability and protects bacteria from host immune responses. LPS is composed of three major regions—lipid A, a core oligosaccharide, and an O antigen. The biosynthesis and assembly of LPS involve a highly coordinated set of enzymatic reactions and transport mechanisms. Additionally, LPS is recognized as an endotoxin,...
386
Antimicrobial Proteins01:23

Antimicrobial Proteins

Antimicrobial proteins are important components of the immune system. They aid the body in combating pathogens by either killing them directly or hindering their replication processes. Four main types of antimicrobial substances are interferons, the complement system, iron-binding proteins, and antimicrobial proteins.
Interferons
Interferons (IFNs) are proteins produced by lymphocytes, macrophages, and fibroblasts infected with viruses. While IFNs cannot prevent viruses from entering and...
12.8K
Lysosomes01:31

Lysosomes

Lysosomes are membrane-enclosed spherical sacs derived from the Golgi apparatus. The most important function of the lysosome is degrading macromolecules and biological polymers that are released during membrane trafficking events such as the secretory, endocytic, autophagic, and phagocytic pathways. The degradation is carried out by several hydrolytic enzymes active in an acidic environment of the lysosomal lumen. These acid hydrolases are involved in cellular processes such as cell signaling,...
25.1K
Intralumenal Vesicles and Multivesicular Bodies01:38

Intralumenal Vesicles and Multivesicular Bodies

Intraluminal vesicles (ILVs) are small vesicles 50-80 nm in diameter formed during the maturation of early endosomes. A specialized endosome containing numerous ILVs is called a multivesicular body (MVB). ILVs contain internalized molecules such as antigens, nucleic acids, proteins, and metabolites. Some of these molecules are released from the MVBs inside exosomes and are transported to other cells. Other MVBs contain molecules that are retained in the ILVs and are later degraded within the...
4.5K
Defense Against Bacterial Pathogens01:31

Defense Against Bacterial Pathogens

The human immune system is a complex network of cells, tissues, and organs that work together to defend the body against bacterial infections. It consists of various immune cells, each playing a specific role in the defense mechanism.
Phagocytes
Phagocytes are the frontline soldiers of the immune system. They include neutrophils and macrophages. Neutrophils are the most abundant type of white blood cell and are quickly mobilized to the site of infection. Macrophages are larger cells that patrol...
2.5K