Immunostimulating properties of intragastrically administered Acetobacter-derived soluble branched...

Area of Science:

• Immunology
• Microbiology
• Biochemistry

Background:

• AC-1, an extracellular polysaccharide from Acetobacter xylinum, is a (1,4)-beta-D-glucan.
• AC-1 induces interleukin-12 (IL-12) and tumor necrosis factor alpha (TNF-α) via Toll-like receptor 4 (TLR-4) signaling in macrophages.
• The role of AC-1 in vivo protective immunity against bacterial infections is not well understood.

Purpose of the Study:

• To investigate the effect of oral AC-1 administration on protective immunity against Listeria monocytogenes.
• To elucidate the underlying mechanisms of AC-1-mediated protection, particularly the involvement of TLR-4 and Th1 responses.

Main Methods:

• Mice were orally administered AC-1 or phosphate-buffered saline (PBS) before and after Listeria monocytogenes infection.
• Survival rates and bacterial loads were assessed.
• Serum IL-12 p40 levels and CD4+ Th1/CD8+ Tc1 responses were measured.
• Experiments were repeated in C3H/HeJ mice with mutated TLR-4.

Main Results:

• AC-1 treatment significantly improved survival rates and reduced bacterial growth in mice infected with L. monocytogenes.
• AC-1 administration led to significantly higher serum IL-12 p40 levels and enhanced CD4+ Th1 and CD8+ Tc1 responses.
• The protective effect of AC-1 was diminished in C3H/HeJ mice with mutated TLR-4, indicating TLR-4 dependency.

Conclusions:

• AC-1 enhances protective immunity against L. monocytogenes infection through TLR-4-mediated induction of IL-12 and augmentation of Th1 responses.
• Oral administration of AC-1, a (1,4)-beta-D-glucan, shows potential for preventing infectious diseases caused by intracellular microorganisms.
• AC-1 represents a promising immunomodulatory agent for enhancing host defense mechanisms.