Non-antibacterial effects of doxycycline

Doxycycline is widely used in the treatment of infections caused by Gram negative and Gram positive microorganisms. According to recent studies, it also has non-antibacterial effects.

Staphylococcal exotoxins are known to be powerful activators of the immune system, leading to massive production of pro-inflammatory cytokines such as tumor necrosis factor alpha (TNF-α), interleukin 1 (IL-1), interferon (IFN) and chemokines (chemotactic monocyte and macrophage proteins). The aforementioned cytokines are key mediators of toxic shock induced by superantigens, stimulating the immune response, which results in damage to body tissue.

The ability of doxycycline to inhibit the production of pro-inflammatory cytokines, in particular IL-1 β, to a degree similar to corticosteroids has been demonstrated. The research by T. Krakauer et al. (USA), the objective was to determine the effect of doxycycline on the staphylococcal antigens induced by the activation of T cells and the production of cytokines by mononuclear cells of human peripheral blood in vitro.

The study showed that doxycycline has a dose-dependent inhibitory effect on the production of cytokines IL-1 β, IL-6, TNF-α and IFN and the chemokines. Complete suppression of the production of the monocyte chemotactic protein and IFN was observed at a doxycycline concentration of 50 µM. The effect of the drug at this concentration also led to a decrease in the production of IL-1 β by 15% -22%, IL-6 by 37% -41%, TNF- α from 21% to 25% and macrophage chemotactic proteins from 59% to 61%.

Thus, doxycycline effectively inhibits the superantigen-induced production of cytokines and chemokines by peripheral blood mononuclear cells. The presence of the drug, as well as the antimicrobial and anti-inflammatory effect, can be an additional advantage in the treatment of toxic shock induced by superantigens.