Helicobacter observed under a microscope./Courtesy of Wikimedia, Yutaka Tsutsumi

Research results have emerged indicating that bacteria causing diseases can also provide benefits. The bacteria known as 'Helicobacter pylori,' which is well known as a cause of gastritis, gastric ulcers, and gastric cancer, may help prevent Alzheimer's disease, Parkinson's disease, and type 2 diabetes.

An international research team, including the Karolinska Institute in Sweden, announced on the 12th that they discovered the protein 'CagA' secreted by Helicobacter pylori prevents amyloid formation. The research findings were published that day in the international journal Science Advances.

When proteins misfold and entangle with each other, they can form abnormal aggregates known as amyloids. When these aggregates accumulate in nerve cells, they can cause lethal damage to brain function, leading to diseases such as Alzheimer's, Parkinson's, and diabetes.

Although amyloids cause disease in humans, they are also a major component of the protective barrier known as a biofilm in bacteria. Biofilms serve to protect bacteria from antibiotics and external attacks. The research team confirmed that the CagA protein secreted by Helicobacter pylori interferes with biofilm formation. Experiments with Escherichia coli and Pseudomonas aeruginosa showed that the CagA protein prevented the bacteria's proteins from aggregating correctly, hindering biofilm formation.

The research team believes that using CagA can block disease-causing amyloids. In fact, CagA inhibited the aggregation of tau and amyloid beta proteins associated with Alzheimer's, alpha-synuclein related to Parkinson's disease, and amylin linked to type 2 diabetes. Previously, CagA was known solely as a toxic protein that induces cancer, but this new role in blocking the abnormal aggregation of disease-causing proteins has been confirmed.

The inhibitory effect of CagA was strongly evident even at very low concentrations. However, the timing of the inhibitory effect varied depending on which protein it acted upon. CagA prevented aggregation by acting on the initial nucleus formation stage in amyloid beta and the growth stage in alpha-synuclein.

The research team analyzed the structure of CagA to find the key region that plays an important role in amyloid inhibition. They proved that using just this part separately also retained the effect of preventing amyloid generation. This could be utilized for future drug development.

Zhen Jin, a researcher at the Karolinska Institute who led the study, noted, "It has been confirmed that Helicobacter pylori can affect not only gastrointestinal diseases but also neurological and metabolic diseases," adding, "The CagA protein may provide a new clue for treating diseases caused by protein misfolding."

References

Science Advances (2025), DOI: https://doi.org/10.1126/sciadv.ads7525