Interleukin-1b-induced growth enhancement of Staphylococcus aureus occurs in biofilm but not planktonic cultures by McLaughlin and Hoogewerf, 2006

The interplay between biofilms and host immune system is still poorly understood.

However, in the last years several discoveries have been made that may help in the understanding of the interactions between biofilms and the host immune system response.

It seems that patients with elevated levels of cytokines develop more frequently bacterial infections. This suggests that cytokines may stimulate bacterial growth and therefore, in this paper, the authors explored the interaction between S. aureus biofilms and the some pro-inflammatory cytokines namely IL-1beta, TNF-alpha, IL-6 and MIP-alpha.

Established S. aureus biofilms were treated with the different cytokines and 6h later the biofilm biomass was determined by crystal violet staining. Planktonic cells were used as control.

Interestingly, the authors observed that IL-1beta lead to a significant increase, in a doses-dependent fashion, of the biofilm biomass but not the growth of planktonic cells. Additionally, the addition of both antibodies anti-IL-1beta or IL-1beta heat denaturated abrogated the increased of biofilm biomass observed before.

The bind of the IL-1beta to bacterial cells was assessed by flow cytometry was also assessed, and it was found that IL-1beta binds more efficiently to biofilms (63%)  than planktonic cells (11%).

Finally, based on these findings, the authors have hypothesized that biofilms may evade the host immune system defenses by growing faster in response to the inflammatory mediators released by activated host defense cells.

Reference of the article summarized above:

McLaughlin RA, Hoogewerf AJ (2006) “Interleukin-1b-induced growth enhancement of Staphylococcus aureus occurs in biofilm but not planktonic cultures.”Microbe Pathogens, 41 (2-3): 67-79.

RM: AF 1427

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