Effects of CRAMP on the gut-brain axis in experimental sepsis

Area of Science:

• Microbiology
• Immunology
• Neuroscience

Background:

• The gut microbiota, intestinal epithelium, and mucosa form a critical defense against pathogens.
• Dysbiosis, an imbalance in gut bacteria, can lead to pathogen translocation, immune dysregulation, and sepsis.
• Antimicrobial peptides, such as cathelicidin antimicrobial peptide (CRAMP), are key components of innate immunity, with complex roles in inflammation during infection.

Purpose of the Study:

• To investigate the role of CRAMP in the inflammatory response, brain tissue damage, and gut microbiota alterations during sepsis.
• To evaluate the protective effects of CRAMP deficiency in a mouse model of sepsis.

Main Methods:

• Cecal ligation and puncture (CLP) procedure to induce polymicrobial sepsis in wild-type and CRAMP knockout mice.
• Quantitative gene expression analysis of inflammatory markers (S100A8, S100A9) in brain tissue.
• Assessment of protein concentrations in brain tissue.
• 16S rRNA sequencing or similar method to analyze changes in the intestinal microbiota composition.

Main Results:

• CRAMP knockout mice exhibited lower gene expression of S100A8 and S100A9 in the prefrontal cortex, hippocampus, and cerebellum compared to wild-type mice post-CLP.
• While protein levels of these markers remained constant, gene expression differences suggest reduced neuroinflammation in CRAMP-deficient mice.
• Wild-type mice showed increased populations of Escherichia coli, Lactobacillus spp., and Enterococcus faecalis 24 hours post-CLP, indicating significant gut dysbiosis, which was less pronounced in CRAMP knockout mice.

Conclusions:

• The absence of CRAMP appears to confer a protective effect in this sepsis model, potentially by mitigating neuroinflammation and gut dysbiosis.
• These findings highlight the complex role of CRAMP in sepsis and suggest CRAMP deficiency may be a therapeutic target.