Abstract for 2022 ISEMPH annual meeting in Lisbon, Portugal:

Pain is among the most common reasons a patient seeks medical care. However, pain itself is not always problematic. Responding to painful stimuli protects an organism from physical harm. Here we suggest another function: pain protects organisms from pathogens. Protection from infection is orchestrated by local effects of pain neuron activation, regulation of pain at the CNS, and subjective experience of pain. Mechanisms underlying the regulation of pain and immunity overlap considerably, suggesting that pain may be another arm of the immune system. Notably, pain is used by clinicians as a sign of likely infection in wounds and after surgery. Some pain neurons express receptors that detect pathogens; when activated, these neurons initiate immune responses against pathogens. One prediction of this hypothesis is that pathogens should engage strategies to block pain. Accordingly, SARS-CoV2 recently was shown encode peptides that interfere with pain. Other parasites and bacteria also disrupt pain signaling, including M. leprae which destroys pain neurons. Because some pathogens block pain, it could be adaptive for hosts to have an anticipatory counter-response against microbial manipulation of the pain system. This could lead to higher pain sensitization. We discuss treatment implications for chronic pain, long COVID, and opioid dependence. 

Authors: Kevin Lozo, Athena Aktipis, Joe Alcock

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