Bacterial Flagellin Triggers Touch-Induced Itch Through Immune Receptor Activation in Skin Nerve Cells
Researchers identified how Pseudomonas aeruginosa bacteria cause mechanical itch—a condition where light touch triggers intense itching—through a specific molecular pathway. The bacterial protein flagellin activates an immune receptor (TLR5) on touch-sensing nerve cells in the skin, disrupting their normal electrical regulation. This discovery reveals a direct microbial-neuronal mechanism underlying infection-related itch and suggests new therapeutic targets.
A new study published on bioRxiv describes how Pseudomonas aeruginosa skin infections trigger alloknesis, a pathological state where gentle touch provokes severe itching. Using an epicutaneous infection model, researchers identified bacterial flagellin as the key virulence factor responsible for this symptom. The flagellin activates Toll-like receptor 5 (TLR5) specifically on Calb1+ A-beta rapidly adapting mechanoreceptors—specialized nerve cells that normally sense light touch. This activation depletes intracellular PIP2 molecules, which normally suppress KCNQ4 ion channels and keep these neurons from firing excessively. With PIP2 depleted, the neurons become hyperexcitable, converting normal tactile stimuli into itch signals. The findings establish a direct microbial-sensory axis at the peripheral nervous system level and provide a framework for understanding how pathogens hijack sensory neurons to cause chronic itch symptoms.
Limitations & open questions
The study's own limitations and open questions are not detailed in the abstract provided. Typical gaps in such research might include: whether this mechanism applies to other bacterial species or only P. aeruginosa; whether the findings translate to human infections; and whether blocking this pathway could effectively treat infection-related itch without compromising immune defense.
What different sources said
- bioRxivCenter
A microbial-sensory axis drives Pseudomonas aeruginosa-induced mechanical itch
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