Clostridial C3 Toxins Enter and Intoxicate Human Dendritic Cells

Area of Science:

• Microbiology
• Immunology
• Cell Biology

Background:

• Clostridium C3 toxins are mono-ADP-ribosyltransferases that inhibit Rho GTPases in monocytic cells.
• C3 toxins enter monocytic cells via endocytosis and translocate into the cytosol, affecting cell functions like migration and phagocytosis.

Purpose of the Study:

• To investigate if C3 toxins target and intoxicate human dendritic cells.
• To explore the potential of C3 toxins as carriers for delivering foreign proteins into dendritic cells.

Main Methods:

• Incubation of immature and mature human dendritic cells with C3 toxins.
• Stimulated emission depletion (STED) microscopy to visualize toxin localization.
• Comparison with the uptake of C. botulinum C2I enzyme.

Main Results:

• C3 toxins are efficiently internalized by both immature and mature human dendritic cells in a time- and concentration-dependent manner.
• Internalized C3 toxins localize within endosomes, suggesting potential as a delivery vehicle.
• The C2I enzyme from C. botulinum C2 toxin showed no uptake, indicating specificity for C3 toxins.

Conclusions:

• Human dendritic cells are identified as novel target cells for clostridial C3 toxins.
• C3 toxins are specifically taken up by dendritic cells via endosomal vesicles.
• C3 toxins show potential for use as carriers to deliver foreign proteins into dendritic cells.