DNA from probiotic bacteria modulates murine and human epithelial and immune function

Area of Science:

• Microbiology
• Immunology
• Gastroenterology

Background:

• The intestinal epithelium distinguishes between harmful and beneficial bacteria.
• Bacterial DNA's role in this recognition process requires further investigation.

Purpose of the Study:

• To determine if bacterial DNA serves as a molecular basis for bacterial recognition by the intestinal epithelium.
• To investigate the immunomodulatory effects of probiotic bacterial DNA.

Main Methods:

• Human HT-29 cell monolayers were treated with bacterial DNA, and responses (IL-8 secretion, NF-kappaB activation, IkappaB levels) were measured.
• Cytokine secretion was assessed in mouse colonic segments and splenocytes.
• IL-10-deficient mice received oral VSL3 DNA to evaluate its impact on colonic inflammation.

Main Results:

• Bacterial DNA differentially modulated IL-8 secretion in HT-29 cells.
• VSL3 DNA inhibited pro-inflammatory signaling pathways (p38 MAPK, NF-kappaB) and proteasome function.
• VSL3 DNA reduced IFN-gamma secretion in mouse colons and splenocytes, and attenuated TNF-alpha release.
• Oral VSL3 DNA treatment in IL-10-deficient mice decreased mucosal cytokine production and improved histologic disease.

Conclusions:

• DNA derived from probiotic bacteria can effectively limit pro-inflammatory epithelial responses.
• Both systemic and oral administration of VSL3 DNA demonstrate therapeutic potential in ameliorating inflammatory conditions.