The Problem
Periodontitis or gum inflammation occurs when harmful bacteria destroy the tissue and bone holding our teeth in place. One of the main bacteria responsible for this is called Aggregatibacter actinomycetemcomitans (or Aa for short). Aa doesn’t just cause gum disease; it can also travel through the body and cause serious heart infections (Infective Endocarditis).
The Mystery
To fight off infections, our body recruits white blood cells called neutrophils. These cells deploy a clever defense mechanism called NETs (Neutrophil Extracellular Traps). Think of NETs as microscopic spiderwebs made of DNA and granule proteins that trap and kill bacteria. Scientists already knew that Aa may escape these traps, but they didn’t know exactly how. Initially, we suspected a well-known toxin produced by the bacteria (called CDT) was used as DNA-cutter to shred the NETs. However, when we removed the toxin from bacteria, it could still destroy the NETs. This meant a different, hidden weapon in Aa was responsible for DNA degradation.
The Discovery
By breaking down the bacteria and analyzing its parts, we discovered the real culprit:
- The Weapon: A specific protein called NadN (NAD nucleotidase).
- The Location: This protein isn’t floating around; it is anchored directly onto the membrane of the bacteria.
- The Proof: When we isolated this NadN protein, it successfully dissolved the immune system’s DNA webs. Furthermore, when we put the NadN protein into a completely harmless bacterium (Lactococcus lactis), that harmless bacterium suddenly gained the ability to destroy the webs too.
Why This Matters
By shifting the focus away from the old suspect (CDT) and identifying NadN as the true culprit, this study gives us a precise new target. This study opens several doors for clinical and potential therapeutic targets in periodontal disease.
Read more: https://www.tandfonline.com/doi/full/10.1080/20002297.2026.2694756
First author: Yaowapa Puanglai
Corresponding author: Fabien Loison
