Inflammation caused by scorpion venom should be blocked immediately, study shows
Tityus serrulatus, the Yellow scorpion, causes more deaths than any other venomous animal in Brazil. Its sting can induce heart attack and pulmonary edema, especially in children and the elderly. According to the Brazilian Health Ministry, more than 156,000 cases of scorpion envenomation, 169 fatal, were reported in the country in 2019.
Researchers at the University of São Paulo (USP) have demonstrated for the first time that in severe cases of scorpion envenomation a systemic neuroimmune reaction produces inflammatory mediators leading to the release of neurotransmitters. A paper reporting the results of their study is publishedin Nature Communications. It suggests the inflammatory process can be inhibited by administration of a corticosteroid almost immediately after the patient is stung.
Besides local inflammation that causes acute pain but does not lead to death, scorpion venom may also trigger a systemic inflammatory reaction resulting in pulmonary edema (excess fluid in the lungs), heart failure and shortness of breath.
“Although a previous study by our group described the inflammatory mechanism that leads to pulmonary edema and death in severe cases, the impact of envenomation on the heart and the link between neurotransmitters and inflammatory mediators weren’t entirely elucidated,” said Lúcia Helena Faccioli, a professor at USP’s Ribeirão Preto School of Pharmaceutical Sciences and principal investigator for the study. “There was no consensus as to whether neurotransmitters or inflammatory mediators were the villains, and whether pulmonary edema leads to cardiac alterations or the other way around. This study suggests inflammatory mediators produced in the lungs not only induce pulmonary edema but also affect the heart via neurotransmitters. The inflammatory process causes various kinds of damage and can lead to death unless it’s blocked very swiftly.”
The study was conducted with São Paulo Research Foundation—FAPESP’s support during the Ph.D. research of Mouzarllem Barros dos Reis as part of a Thematic Project for which Faccioli is principal investigator.
This was an in vitro and in vivo study in mice focusing on an investigation of the inflammatory process triggered by envenomation and its association with neurotransmitters. The scorpion venom spreads rapidly from the sting site into the bloodstream. In severe cases, recognition of the venom by macrophages (immune cells) results in the release of inflammatory mediators, especially interleukin-1beta (IL-1β), leading to release of prostaglandin E2 (PGE2), which in turn induces production of the neurotransmitter acetylcholine. Produced in the lungs, these mediators cause both pulmonary edema and cardiac alterations.
