The time course of the inflammatory response to the Salmonella typhi vaccination

The Salmonella typhi vaccination induces transient increases in inflammatory-responsive cytokines and molecules. For instance, it causes small, mild increases in interleukin-6 (IL-6) within a few hours and C-reactive protein (CRP) within 24 h. No study has charted either the time course of the inflammatory response to this vaccine or any associated changes in mood, physical symptoms, and cardiac function. In a blinded crossover experimental design, eight participants received the S. typhi vaccine (vaccination condition) and a saline (control condition) injection on two separate days, at least one week apart. Blood samples and mood ratings were collected at 0, 4, 5, 6, 7, 8 and 24 h post-injection, physical symptoms and pain were assessed at 4–8 and 24 h post-injection, and cardiovascular function was recorded until 8 h post-injection. Repeated measures analyses of variance and polynomial trend analyses compared the timecourse of the response patterns between the two conditions. Whereas there were no temporal changes in the control condition, the vaccination increased granulocytes, IL-6, TNF-α, and CRP (all p’s < .05). Specifically, the granulocytes, IL-6 and TNF-α peaked after 6–8 h while CRP peaked after 24 h. This vaccine-induced mild inflammatory response was not accompanied by any changes in mood or cardiovascular activity. We also found that participants tended to report more pain in the injected limb in the vaccination condition (p < .07). In sum, our study charted the timecourse of key inflammatory-responsive markers following S. typhi vaccination and identified the timing of their modest peaks. It is worth noting that changes in these markers were not accompanied by any notable changes in mood or cardiovascular activity, and thus the S. typhi vaccination is a suitable method to induce increases in inflammatory-responsive markers, without altering mood or cardiovascular parameters.

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► The study characterized the inflammatory response to S typhi vaccination over 24 h, revealing changes in inflammation but not mood or cardiac measures.