ZIP8 A391T Crohn's Disease-Linked Risk Variant Induces Colonic Metal Ion Dyshomeostasis, Microbiome Compositional...

Area of Science:

• Genetics
• Microbiology
• Gastroenterology

Background:

• Crohn's disease pathogenesis involves genetic and environmental factors, with the gut microbiome playing a key role.
• A specific variant (rs13107325) in the SLC39A8 gene (encoding ZIP8 metal transporter) is linked to Crohn's disease and altered colonic microbiome.
• This variant causes an A391T amino acid substitution, potentially affecting metal ion homeostasis at the gut lining.

Purpose of the Study:

• To investigate if the SLC39A8 A391T variant impacts metal ion homeostasis in the gut.
• To determine if this alteration in metal availability leads to gut dysbiosis (microbiome imbalance).
• To explore the link between variant-induced dysbiosis and the development of intestinal inflammation.

Main Methods:

• Generated a mouse model with the SLC39A8 A393T variant (equivalent to human A391T).
• Analyzed trace element levels in colonic tissue and lumen of variant and wild-type mice.
• Performed 16S rRNA gene sequencing to assess microbiome composition and diversity at multiple ages.
• Conducted histological analysis of colon tissue to evaluate inflammation.

Main Results:

• Homozygous variant mice showed increased cobalt in colonic mucosa but decreased levels of multiple metals (Fe, Zn, Mn, Co, Cu, Cd) in the colonic lumen.
• Significant alterations in gut microbiome beta diversity were observed in variant mice across different ages.
• Spontaneous intestinal inflammation was detected in older variant mice (10 months), but not in younger ones (5 months).
• Pathway analysis indicated differential enrichment of metal-dependent pathways in the microbiomes of variant mice.

Conclusions:

• The SLC39A8 A391T variant appears to restrict metal availability to the gut microbiota, promoting adaptive compositional changes.
• Variant-associated gut dysbiosis precedes the onset of intestinal inflammation.
• This study supports the role of genetic risk variants as modifiers of the microbiome in disease development.