Mihai Netea and colleagues published two papers back-to-back in The Journal of Clinical Investigation. 

29 July 2020

Mihai Netea, theme Infectious diseases and global health, together with his research team published back-to-back in The Journal of Clinical Investigation. 

Trained immunity

The anti-tuberculosis vaccine Bacillus Calmette-Guérin (BCG) reduces overall infant mortality. Induction of innate immune memory, also termed trained immunity, contributes towards protection against heterologous infections.

''Circadian rhythm influences induction of trained immunity by BCG vaccination'' 

In the first article, Mihai Netea and his research group investigated the effect of BCG administration time on the induction of trained immunity, since immune cells display oscillations in numbers and function throughout the day. They showed that BCG vaccination in the morning induces stronger trained immunity and adaptive responses compared to evening vaccination. Future studies should take vaccine administration time into account when studying specific and non-specific effects of vaccines: early morning should be the preferred moment of BCG administration.
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''BCG vaccination in humans inhibits systemic inflammation in a sex-dependent manner''

The second article is aimed at elucidating the overall impact of BCG vaccination on the inflammatory status of an individual. While induction of trained immunity may suggest increased inflammation, BCG vaccination has been epidemiologically associated with a reduced incidence of inflammatory and allergic diseases. They showed that, while BCG vaccination enhanced cytokine responses to restimulation, it reduced systemic inflammation. This effect was validated in three smaller cohorts, and was much stronger in men than in women. In addition, baseline circulating inflammatory markers were associated with ex vivo cytokine responses (trained immunity) after BCG vaccination.
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