Beta-Defensins: How Antimicrobial Peptides Farm the Microbiome to Keep Us Healthy

Narrative review synthesizing recent evidence on beta-defensin biology, focusing on their roles in microbiome management, mucosal immunity, host-microbe interactions, gene family evolution, and neonatal immune programming.

As medicine shifts from antibiotic-based microbial clearance to microbiome-aware approaches, understanding how the body naturally manages its microbial communities becomes essential. Beta-defensins represent the body's own selective antimicrobial system — one that's been refined over millions of years of evolution. Harnessing their biology could lead to treatments that fight infections without destroying beneficial microbiomes, addressing a critical limitation of current antibiotics.

The antimicrobial peptide field has undergone a paradigm shift from viewing these molecules as simple bacteria-killers to recognizing them as sophisticated microbiome managers. This has profound implications for treating infections, managing inflammatory diseases, and even understanding how immune programming in early life shapes lifelong health. Beta-defensins are at the forefront of this shift, connecting innate immunity, microbiome science, and developmental biology.

This is a narrative review that synthesizes existing evidence without systematic methodology. Much of the evidence for beta-defensin microbiome management comes from animal studies, particularly cattle (the senior author's area). Mechanistic details of how beta-defensins selectively shape microbial communities are still being elucidated. The clinical translation of defensin biology into therapeutic applications remains largely theoretical.