Invisible smart bug fights gum disease
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How the engineered HEpM remodel the periodontal microenvironment.
view moreCredit: Lili Chen
Periodontitis—a chronic inflammatory disease that damages the gums and bones supporting teeth—affects nearly half of adults worldwide. Current treatments often fail because they cannot simultaneously eliminate stubborn bacterial biofilms and calm the runaway inflammation that follows.
Now, researchers have engineered a living bacterium that does both, in the right order.
In a study published in Dental Research, a team of researchers from China and Australi started with Escherichia coli Nissle 1917 (EcN), a harmless probiotic, and gave it three clever upgrades. First, they loaded it with nanoparticles containing metronidazole, an antibiotic that only becomes active in the oxygen‑free environment of a diseased gum pocket. Second, they equipped the bacterium with a hemoglobin from a bacterium that loves oxygen (Vitreoscilla). This "invisible cloak" protects the probiotic from its own antibiotic. Finally, they added a heat-sensitive genetic switch that turns on an antioxidant enzyme (superoxide dismutase) only when triggered by a mild warm stimulus.
"We wanted a therapy that respects the natural course of the disease—first clean up the harmful microbes, then resolve the inflammation," says senior and co-corresponding author Lili Chen. "Our design allows us to remotely activate the anti‑inflammatory phase precisely when the first job is done."
In a rat model of periodontitis, the two‑stage treatment dramatically reduced the key pathogens P. gingivalis and F. nucleatum and restored a healthy-like oral microbiome. After heat activation, the engineered bacteria lowered oxidative stress and promoted repair of the periodontal ligament and alveolar bone. Single-cell sequencing revealed that fibroblasts became the central hub of tissue‑regenerating signals.
"What if something goes wrong? To that end, we built in a fail‑safe: the same hemoglobin that acts as an 'invisible cloak' also serves as a natural sonosensitizer," shares Chen. "Additionally, we introduced a short, low‑energy ultrasound pulse (1 W/cm², 5 min), which safely lyses the engineered bacteria with no trace left behind."
"This is the first time a living bacterium has been programmed to execute a temporal, two‑step therapeutic program inside the body," says co-corresponding author Yuzhou Wu. "The platform could be adapted for other inflammatory diseases where microbial imbalance and oxidative stress play a role."
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Contact the author: Lili Chen, Department of Stomatology, Union Hospital, Tongji Medical College, Hubei Province Key Laboratory of Oral and Maxillofacial Development and Regeneration, School of Stomatology, Tongji Medical College, Huazhong University of Science and Technology, Wuhan, P. R. China. E-mail: chenlili1030@hust.edu.cn.
The publisher KeAi was established by Elsevier and China Science Publishing & Media Ltd to unfold quality research globally. In 2013, our focus shifted to open access publishing. We now proudly publish more than 200 world-class, open access, English language journals, spanning all scientific disciplines. Many of these are titles we publish in partnership with prestigious societies and academic institutions, such as the National Natural Science Foundation of China (NSFC).
Method of Research
Experimental study
Subject of Research
Animals
Article Title
An "anaerobic invisible" genetically engineered bacterium for periodontitis treatment through temporal modulation on microenvironment
Don't rush into braces with disc displacement: experts reveal the science of sequential therapy
KeAi Communications Co., Ltd.
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This illustration was drafted by Prof. Yang himself and finished by his students. It depicts the sequential strategy for combined joint–mandible–occlusion diagnosis and treatment. Before and after the disc reduction surgery, preoperative orthodontics, postoperative jaw position adjustment and stabilization, and postoperative comprehensive orthodontic treatment are performed.
view moreCredit: Guo Bai and Qianyang Xie
A new study published in Dental Research reveals that while proper orthodontics can help a healthy jaw joint, incorrect treatment can worsen disc displacement and even cause bone loss. The authors, from Shanghai Ninth People's Hospital, created a "Joint-Mandible-Occlusion" sequential model: first surgically reposition the disc, then address teeth alignment. This approach aims to fix the joint first to ensure stable, long-term results for both bite and facial appearance.
"The aim is to promote balanced bilateral joint growth in growing patients and maintain joint stability in adults," says co-corresponding author Chu Yang. "This idea underpins a pioneering approach to treating temporomandibular joint (TMJ) disc displacement, a common yet often misunderstood condition."
The authors noted that teenagers with receding chins or crooked teeth are usually told their issues were purely dental. "But the real cause is often the jaw joint itself: when the articular disc— a cartilage shock absorber—slips, it can erode the jawbone's condyle over time, leading to facial asymmetry, receding chins and misaligned bites," adds Yang. "This changes treatment entirely."
"Notably, traditional orthodontics alone often relapses, as the joint problem remains unaddressed. For adolescents, this unlocks balanced jaw growth; for adults, it stops bone erosion and restores joint stability," says Yang. "Many patients feel no pain, unknowingly suffering silent bone loss. Screening joint health before orthodontics is key—this root-cause approach delivers stable, long-term results, improving bite, facial harmony and jaw health."
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Contact the author: Please contact Guo Bai and Qianyang Xie from Department of Oral Surgery, Shanghai Ninth People's Hospital, Shanghai Jiao Tong University School of Medicine, College of Stomatology, Shanghai Jiao Tong University via surgeonb@163.com and Xieqianyang86@126.com.
The publisher KeAi was established by Elsevier and China Science Publishing & Media Ltd to unfold quality research globally. In 2013, our focus shifted to open access publishing. We now proudly publish more than 200 world-class, open access, English language journals, spanning all scientific disciplines. Many of these are titles we publish in partnership with prestigious societies and academic institutions, such as the National Natural Science Foundation of China (NSFC).
Method of Research
Literature review
Subject of Research
People
Article Title
Anterior disc displacement in the temporomandibular joint and orthodontic treatment
