A parasitic worm can suppress pain signals in the human body

Amazing stuff!

"A parasitic worm can suppress pain signals in the human body, allowing it to invade without triggering the immune system, per new research published in The Journal of Immunology; the findings about the worm, Schistosoma mansoni, and its tactics for blocking neural pathways could lead to breakthroughs in pain management."

"... New research, ... discovered that a parasitic worm suppresses neurons in the skin to evade detection. The researchers suggest that the worm likely evolved this mechanism to enhance its own survival, and that the discovery of the molecules responsible for the suppression could aid in the development of new painkillers. ..."

From the abstract:

"Immunity against skin-invasive pathogens requires mechanisms that rapidly detect, repel, or immobilize the infectious agent. While bacteria often cause painful cutaneous reactions, host skin invasion by the human parasitic helminth Schistosoma mansoni often goes unnoticed.

This study interrogated whether pain-sensing skin afferents marked by expression of the ion channel Transient Receptor Potential Vanilloid 1 (TRPV1) contributed to the detection and initiation of skin immunity against S. mansoni.

Data show that percutaneous S. mansoni infection significantly reduced thermal pain sensitivity evoked by TRPV1+ neurons. Consistently, isolated skin sensory neurons from infected mice had significantly reduced calcium influx and neuropeptide release in response to the TRPV1 agonist capsaicin compared to neurons from naïve controls.

Using gain- and loss-of-function approaches to test whether TRPV1+ neurons initiate host-protective responses revealed that TRPV1+ neurons limit S. mansoni skin entry and migration into the pulmonary tract. Moreover, TRPV1+ neurons were both necessary and sufficient to promote proliferation and cytokine production from dermal γδ T cells and CD4+ T helper cells, as well as to enhance neutrophil and monocyte recruitment to the skin.

Taken together, this work suggests that S. mansoni may have evolved to manipulate TRPV1+ neuron activation as a countermeasure to limit IL-17-mediated inflammation, facilitating systemic dissemination and chronic parasitism."

Global Health NOW: Renewed Outrage Over FGM in The Gambia; Burma’s Junta Restricts ART Access; and South Sudan’s Fragile Psychological Care System

The parasite that turns off your body’s pain alarm and sneaks in (original news release)

TRPV1+ neurons promote cutaneous immunity against Schistosoma mansoni (open access)

Graphical abstract