Disgusting odors trigger the oral immune system

Stephanie Anja Juran; Arnaud Tognetti; Johan N Lundström; Lalit Kumar; Richard J Stevenson; Mats Lekander; Mats J Olsson

doi:10.1093/emph/eoac042

Disgusting odors trigger the oral immune system

Evol Med Public Health. 2022 Dec 15;11(1):8-17. doi: 10.1093/emph/eoac042. eCollection 2023.

Authors

Stephanie Anja Juran¹, Arnaud Tognetti¹, Johan N Lundström¹, Lalit Kumar², Richard J Stevenson³, Mats Lekander^{1

4

5}, Mats J Olsson¹

Affiliations

¹ Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.
² Department of Women's and Children's Health, Karolinska Institutet, Stockholm, Sweden.
³ Department of Psychology, Macquarie University, North Ryde, NSW, Australia.
⁴ Department of Psychology, Stockholm University, Stockholm, Sweden.
⁵ Osher Center for Integrative Health, Department of Clinical Neuroscience, Karolinska Institutet, Stockholm, Sweden.

Abstract

Recent research has characterized the behavioral defense against disease. In particular the detection of sickness cues, the adaptive reactions (e.g. avoidance) to these cues and the mediating role of disgust have been the focus. A presumably important but less investigated part of a behavioral defense is the immune system response of the observer of sickness cues. Odors are intimately connected to disease and disgust, and research has shown how olfaction conveys sickness cues in both animals and humans. This study aims to test whether odorous sickness cues (i.e. disgusting odors) can trigger a preparatory immune response in humans. We show that subjective and objective disgust measures, as well as TNFα levels in saliva increased immediately after exposure to disgusting odors in a sample of 36 individuals. Altogether, these results suggest a collaboration between behavioral mechanisms of pathogen avoidance in olfaction, mediated by the emotion of disgust, and mechanisms of pathogen elimination facilitated by inflammatory mediators. Disgusting stimuli are associated with an increased risk of infection. We here test whether disgusting odors, can trigger an immune response in the oral cavity. The results indicate an increase level of TNFα in the saliva. This supports that disease cues can trigger a preparatory response in the oral cavity.