Recent research using the 5XFAD Alzheimer’s mouse model reveals that gut immune cell populations, particularly CXCR4+ IgA-producing B cells, migrate into the brain and contribute to disease pathology. Elevated CXCL12 expression in brain glial cells appears to guide this migration. A high-fiber diet modulates these immune changes and alleviates symptoms, highlighting the gut-brain axis’s role in neuroinflammation. These findings open new avenues for therapeutic interventions targeting systemic immune interactions in Alzheimer’s disease.