Chlamydia muridarum Infection Impacts Murine Models of Intestinal Inflammation and Cancer

Area of Science:

• Microbiology
• Immunology
• Gastroenterology

Background:

• Chlamydia muridarum (Cm) is a prevalent pathogen in mouse research colonies.
• Its impact on experimental models of gastrointestinal disease is not well understood.
• Persistent colonization of the murine gut by Cm necessitates investigation into its effects.

Purpose of the Study:

• To evaluate the impact of Cm colonization on established mouse models of intestinal inflammation and tumorigenesis.
• To assess Cm's influence on Citrobacter rodentium (Cr), Trichuris muris (Tm), and Il10-/- mouse models.
• To determine Cm's effect on ApcMin/+ mice undergoing DSS-induced tumorigenesis.

Main Methods:

• Mice (C57BL/6J, Il10-/- , ApcMin/+) were colonized with Cm via cohousing.
• Colonized mice were challenged with Cr, Tm, or DSS.
• Il10-/- mice were also assessed with and without Helicobacter hepaticus co-infection.
• Lesion severity and tumor development were evaluated using a semi-quantitative scoring system.

Main Results:

• Cm infection attenuated Cr-associated colitis (p=0.03).
• Cm had no significant effect on Tm-associated pathology (p=0.22).
• Cm worsened colitis in Il10-/- mice lacking H. hepaticus (p=0.007).
• Cm reduced DSS-induced colonic tumorigenesis in ApcMin/+ mice (p=0.004).

Conclusions:

• Cm colonization differentially affects various models of intestinal inflammation and tumorigenesis.
• The presence of Cm in mouse colonies should be considered a potential variable in experimental outcomes.
• Further research is needed to elucidate the mechanisms behind Cm's varied effects.