Related Experiment Video

Updated: May 16, 2026

Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death
09:18

Identification of Intracellular Signaling Events Induced in Viable Cells by Interaction with Neighboring Cells Undergoing Apoptotic Cell Death

Published on: December 27, 2016

[Macrophage apoptosis as a mechanism of pathogenic effect of diphtheria infectious agent]

G G Kharseeva, É L Alutina, G I Vasil'eva

    Zhurnal Mikrobiologii, Epidemiologii I Immunobiologii
    |November 21, 2012
    PubMed
    Abstract

    Insights

    Corynebacterium diphtheriae causes macrophage apoptosis via exotoxin and surface structures. This mechanism contributes to prolonged bacterial carriage, especially with Streptococcus pyogenes.

    Area of Science:

    • Immunology
    • Microbiology
    • Cell Biology

    Context:

    • Macrophages are key immune cells involved in host defense.
    • Bacterial pathogens employ various strategies to evade immune responses.
    • Apoptosis, or programmed cell death, is a critical cellular process.

    Purpose:

    • To investigate the apoptogenic effect of toxigenic Corynebacterium diphtheriae strains on mouse peritoneal macrophages in vitro.
    • To elucidate the roles of diphtheria exotoxin, surface structures, and pathogenicity enzymes in inducing macrophage apoptosis.

    Summary:

    • Corynebacterium diphtheriae induces apoptosis in macrophages through its diphtheria exotoxin at early stages and surface structures/pathogenicity enzymes at later stages.
    • Morphological changes in macrophages stained with Romanovsky-Giemsa were used to evaluate apoptosis.
    • Other bacterial strains, including Corynebacterium pseudodiphtheriticum, Staphylococcus aureus, and Streptococcus pyogenes, were included for comparative analysis.

    Impact:

    • Understanding the apoptogenic activity of C. diphtheriae provides insights into its pathogenesis.
    • The findings suggest that macrophage apoptosis is a mechanism by which C. diphtheriae evades host immunity.
    • Increased apoptogenic activity in C. diphtheriae and S. pyogenes co-infections may explain persistent bacterial carriage and chronic ENT conditions.

    More Related Videos

    Experimental Analysis of Apoptotic Thymocyte Engulfment by Macrophages06:47

    Experimental Analysis of Apoptotic Thymocyte Engulfment by Macrophages

    Published on: May 24, 2019

    Saturated Fatty Acids Induce Ceramide-associated Macrophage Cell Death08:26

    Saturated Fatty Acids Induce Ceramide-associated Macrophage Cell Death

    Published on: October 31, 2017

    Related Concept Videos

    Diphtheria01:28

    Diphtheria

    Diphtheria is an acute, toxin-mediated infectious disease that primarily affects the upper respiratory tract. It is caused by Corynebacterium diphtheriae, a Gram-positive, pleomorphic rod that lacks spore-forming capability and exhibits a characteristic club-shaped morphology under microscopic examination. While C. diphtheriae can asymptomatically colonize mucosal surfaces, clinical disease manifests only when the bacterial strain is lysogenized by a specific β-corynephage. This phage...
    Phagocytosis of Apoptotic Cells01:17

    Phagocytosis of Apoptotic Cells

    Cells undergoing apoptosis form apoptotic bodies that must be removed immediately to prevent inflammation, autoimmune diseases, and necrosis. Phagocytosis is carried out by professional phagocytes such as macrophages or  immature dendritic cells. Non-professional phagocytes such as  epithelial cells and fibroblasts also take part in this process; however, they are not as effective as professional phagocytes. 
    Normal cells contain receptors that prevent them from being recognized by phagocytes.
    The Extrinsic Apoptotic Pathway01:17

    The Extrinsic Apoptotic Pathway

    The extrinsic apoptotic pathway is initiated when extracellular death-inducing signals, such as specific cytokines, activate the death receptors expressed on the cell surface. The immune cells involved in this pathway are natural killer cells (NK cells) and cytotoxic T-lymphocytes. NK cells are critical in innate immune response, while cytotoxic T-lymphocytes are associated with adaptive immune response. These cells recognize specific receptors expressed on the altered cells and activate...
    Cellular Injury V: Apoptosis and Autophagy01:22

    Cellular Injury V: Apoptosis and Autophagy

    Cells respond to damage and stress through highly coordinated processes that decide whether they survive or undergo controlled self-destruction. Two major pathways involved in this regulation are apoptosis, a type of programmed cell death, and autophagy, a survival mechanism that helps cells adapt to adverse conditions.ApoptosisApoptosis removes aged or injured cells to maintain tissue balance. During this process, the cell shrinks, chromatin condenses and fragments, and membrane-bound...
    Apoptosis01:30

    Apoptosis

    Apoptosis is a combination of two Greek words, 'apo' and 'ptosis,' meaning separation and falling off, respectively. Hippocrates used this word to describe gangrene, which was caused due to bandaging of fractured bones. Apoptosis was distinguished from necrosis in 1970 when John Kerr reported observations of morphological changes occurring during apoptosis. During one experiment, he observed that the disruption of blood supply to the liver tissue resulted in a size reduction of the tissue.
    Overview of Cell Death01:30

    Overview of Cell Death

    Cell death is an essential process where the body gets rid of old or damaged cells. Cell proliferation and death need to be balanced, as an imbalance between the two may lead to cancer or autoimmune diseases.
    Cell death was observed in the early 19th century, but there was no experimental evidence to prove it. In 1842, Carl Vogt first discovered cell death in a metamorphic toad; however, it was not termed ‘cell death.’ Scientists discovered different cell death pathways only in the 20th century...