Exposure to TiO2 nanoparticles increases Staphylococcus aureus infection of HeLa cells

Abstract

BackgroundTitanium dioxide (TiO2) is one of the most common nanoparticles found in industry ranging from food additives to energy generation. Approximately four million tons of TiO2 particles are produced worldwide each year with approximately 3000 tons being produced in nanoparticulate form, hence exposure to these particles is almost certain.ResultsEven though TiO2 is also used as an anti-bacterial agent in combination with UV, we have found that, in the absence of UV, exposure of HeLa cells to TiO2 nanoparticles significantly increased their risk of bacterial invasion. HeLa cells cultured with 0.1 mg/ml rutile and anatase TiO2 nanoparticles for 24 h prior to exposure to bacteria had 350 and 250 % respectively more bacteria per cell. The increase was attributed to bacterial polysaccharides absorption on TiO2 NPs, increased extracellular LDH, and changes in the mechanical response of the cell membrane. On the other hand, macrophages exposed to TiO2 particles ingested 40 % fewer bacteria, further increasing the risk of infection.ConclusionsIn combination, these two factors raise serious concerns regarding the impact of exposure to TiO2 nanoparticles on the ability of organisms to resist bacterial infection.Electronic supplementary materialThe online version of this article (doi:10.1186/s12951-016-0184-y) contains supplementary material, which is available to authorized users.

The antimicrobial activity of nanoparticles: present situation and prospects for the future

“…Thereafter, NPs interact with the bacterial cell's basic components, such as DNA, lysosomes, ribosomes, and enzymes, leading to oxidative stress, heterogeneous alterations, changes in cell membrane permeability, electrolyte balance disorders, enzyme inhibition, protein deactivation, and changes in gene expression. [90][91][92] The following mechanisms are the most frequently proposed in current research: oxidative stress, 11 metal ion release, 93 and non-oxidative mechanisms. 13 Oxidative stress ROS-induced oxidative stress is an important antibacterial mechanism of NPs.…”

Titanium exposure and human health

“…The present oral and IV study concluded that very low oral bioavailability, along with slow elimination might result in potential tissue accumulation . Xu et al found that exposure to TiO 2 NPs increased Staphylococcus aureus infection of HeLa cells. In their experiment when HeLa cells were pretreated with TiO 2 followed by exposure to S. aureus bacteria, their data showed that the number of bacteria associated with the HeLa cell membrane increased.…”

“…Also, a substantial increase in the number of bacteria per cell indicated that the cell membrane became more permeable to the bacteria. Their results indicate that exposure of tissue to TiO 2 NPs may significantly increase the risk of bacterial infection . Subacute and chronic changes from TiO 2 NPs exposure were reported to induce pulmonary response in rabbits.…”

“…Their results indicate that exposure of tissue to TiO 2 NPs may significantly increase the risk of bacterial infection. 15 Subacute and chronic changes from TiO 2 NPs exposure were reported to induce pulmonary response in rabbits. There were limitations in that the sequential acute changes following TiO 2 exposure were not investigated.…”

Nonactivated titanium-dioxide nanoparticles promote the growth ofChlamydia trachomatisand decrease the antimicrobial activity of silver nanoparticles

“…The observed TiO 2 growth increase of C. trachomatis was unexpected, but not without precedent in the literature. A recent study by Xu et al (2016) showed that nonactivated TiO 2 NPs increased the attachment/internalization of Staphylococcus aureus to HeLa cells. HeLa cells treated with 100 lg ml À1 TiO 2 NPs (the same concentration that increased the growth of C. trachomatis by about 400% in our study) for 24 h resulted in a 250-350% increase of S. aureus attachment/internalization.…”